DISTRIBUTED INDEPENDENT SECONDARY PRESSURE REGULATING OPEN-CIRCUIT PUMP-CONTROLLED HYDRAULIC SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims priority to the Chinese Patent Application No. 202411318792.7, filed on Sep. 21, 2024, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

[0002]The present disclosure generally relates to a field of hydraulic circuit control technology, and in particular to a distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system.

BACKGROUND

[0003]Hydraulic excavators, as typical construction machinery, are extensively used in fields such as building construction and mining. Currently, hydraulic excavators primarily employ variable-displacement hydraulic pumps or motors driven by constant-speed diesel engines as their power source to provide energy to high-pressure hydraulic oil. The energy is then distributed and transmitted through pipelines and control valves to drive a plurality of hydraulic cylinders and hydraulic motors, i.e., constituting a centralized “volumetric-throttling” speed regulation system. However, this system suffers from issues such as pressure loss at openings of the control valves, prolonged operation of the engines and hydraulic pumps or motors in inefficient zones, and dissipation of large-capacity kinetic and potential energy. These issues not only result in high fuel consumption in construction machinery but also lead to issues like exhaust emissions and heat generation, further hindering the development of construction machinery toward energy conservation, emission reduction, and environmental sustainability.

[0004]The existing electrification solutions for excavators essentially involve replacing traditional internal combustion engines with electric motors that have high energy conversion efficiency. However, current technological improvements to the hydraulic system remain insufficient. Current energy-saving systems, such as hybrid power and independent metering technologies, still adopt a centralized drive approach. Although these systems can enhance the energy efficiency of hydraulic systems to a certain extent, significant energy losses, such as throttling and overflow losses, still exist. Moreover, following the electrification of excavators, new challenges like large battery volume and short endurance time will emerge. Therefore, there remains a fundamental need to improve the energy efficiency of hydraulic systems.

[0005]Pump-controlled systems can essentially eliminate throttling losses in hydraulic systems, thereby helping to improve the energy efficiency of hydraulic systems. However, common distributed independent single-pump single-actuator pump-controlled hydraulic systems generally suffer from various issues. The patent literature with publication number 202210816720.X discloses a distributed independent variable-speed closed-circuit pump-controlled hydraulic system for excavators. This system consists of four pump-controlled hydraulic subsystems, and the four pump-controlled hydraulic subsystems are integrated as electro-hydraulic actuators independently installed on corresponding hydraulic cylinders or hydraulic motors. Within this system, part of the kinetic and potential energy of the excavator is converted into electrical energy through electric components or generator units for storage and utilization, while another part of the energy is stored and utilized by high-pressure accumulators in the third and fourth pump-controlled hydraulic systems, offering the system high energy-saving benefits. However, due to its working mode of using a single pump to drive a single actuator, the system requires the pump to independently cover all the load characteristics demanded by its corresponding actuator. This not only leads to a high installed power of the system but also results in issues such as a narrow operating range, low compactness due to large-sized hydraulic pump or motor units, and high costs. The patent literature with publication number 202310324055.7 discloses a multi-electromagnetic valve-controlled discrete four-chamber hydraulic cylinder system. This system still employs pump-controlled drive and uses a high-pressure accumulator directly to connect to a specific rodless chamber of the hydraulic cylinder to achieve energy recovery, also offering high energy-saving benefits. Meanwhile, since the actuator in this system uses three different electromagnetic valves to combine different chambers of the hydraulic cylinder, it can discretely change its effective piston area, enabling the system to achieve a wider speed range and a wider output force range (i.e., a broader operating range). However, since it still adopts the single-pump-single-actuator working mode, the requirement for the rated output power of the hydraulic pump or motor unit under a heavy-load condition is high, i.e., a larger-sized hydraulic pump or motor unit is needed. Secondly, the actuator in this system consists of three two-chamber cylinders connected in parallel, lacking compactness and cost-effectiveness.

SUMMARY

[0006]One or more embodiments of the present disclosure provide a distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system, comprising a secondary pressure regulating transmission control system and a hydraulic power-supply system, the secondary pressure regulating transmission control system including a first hydraulic control system, a second hydraulic control system, and a third hydraulic control system. Each of the first hydraulic control system, the second hydraulic control system, and the third hydraulic control system includes an integrated electro-hydraulic actuator. The integrated electro-hydraulic actuator of the first hydraulic control system is mounted on a first hydraulic cylinder, the integrated electro-hydraulic actuator of the second hydraulic control system is mounted on a second hydraulic cylinder, and the integrated electro-hydraulic actuator of the third hydraulic control system is mounted on a third hydraulic cylinder. The first hydraulic control system is configured to control a movable arm, the second hydraulic control system is configured to control a stick, and the third hydraulic control system is configured to control a bucket. The second hydraulic control system utilizes a three-position four-way electromagnetic switching valve to achieve four-quadrant operation switching of the stick.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]The present disclosure will be further illustrated by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, the same counting denotes the same structure, wherein:

[0008]FIG. 1 is a schematic diagram illustrating a distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure;

[0009]FIG. 2 is a schematic diagram illustrating a first hydraulic control system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure;

[0010]FIG. 3 is a schematic diagram illustrating a second hydraulic control system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure;

[0011]FIG. 4 is a schematic diagram illustrating a third hydraulic control system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure;

[0012]FIG. 5 is a schematic diagram illustrating a hydraulic power-supply system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure;

[0013]FIG. 6 is a schematic diagram illustrating an exemplary parameter prediction model according to some embodiments of the present disclosure; and

[0014]FIG. 7 is a flowchart illustrating an exemplary process for determining a proportional coefficient, an integral coefficient, and a differential coefficient corresponding to a pressure feedback control signal according to some embodiments of the present disclosure.

[0015]Attachment markers: 1, first hydraulic cylinder; 2, second hydraulic cylinder; 3, third hydraulic cylinder; 4, first pressure sensor I; 5, first pressure sensor II; 6, second pressure sensor I; 7, second pressure sensor II; 8, third pressure sensor I; 9, third pressure sensor II; 10, second electromagnetic switch switching valve I; 13, first electromagnetic switch switching valve I; 14, first electromagnetic switch switching valve II; 15, first electromagnetic switch switching valve III; 16, first electromagnetic switch switching valve IV; 17, second electromagnetic switch switching valve II; 19, third electromagnetic switch switching valve I; 20, third electromagnetic switch switching valve II; 21, third electromagnetic switch switching valve III; 22, first energy supply electromagnetic switch switching valve; 23, second energy supply electromagnetic switch switching valve; 24, first relief valve; 25, second relief valve; 26, third relief valve; 27, energy supply relief valve I; 29, energy supply constant pressure pump; 30, first hydraulic pump; 31, second hydraulic pump; 32, third hydraulic pump; 33, first energy supply check valve; 35, second energy supply check valve; 36, energy supply cooler; 37, energy supply filter; 38, energy supply electric motor; 39, first electric motor; 40, second electric motor; 41, third electric motor; 42, hydraulic power-supply system; 43, first hydraulic control system; 44, second hydraulic control system; 45, third hydraulic control system; 46, secondary pressure regulating transmission control system.

DETAILED DESCRIPTION

[0016]The present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. The same component is denoted by the same counting. It should be noted that the terms “front,” “rear,” “left,” “right,” “up,” and “down” used in the following description refer to directions in the drawings. The terms “bottom” and “top,” “inner,” and “outer” refer to directions toward or away from the geometric center of a specific component, respectively.

[0017]FIG. 1 is a schematic diagram illustrating a distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure. FIG. 2 is a schematic diagram illustrating a first hydraulic control system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure. FIG. 3 is a schematic diagram illustrating a second hydraulic control system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure. FIG. 4 is a schematic diagram illustrating a third hydraulic control system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure. FIG. 5 is a schematic diagram illustrating a hydraulic power-supply system in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system according to some embodiments of the present disclosure.

[0018]The present disclosure provides a distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system including a secondary pressure regulating transmission control system and a hydraulic power-supply system. The secondary pressure regulating transmission control system includes a first hydraulic control system, a second hydraulic control system, and a third hydraulic control system. Each of the first hydraulic control system, the second hydraulic control system, and the third hydraulic control system includes an integrated electro-hydraulic actuator. The integrated electro-hydraulic actuator of the first hydraulic control system is mounted on a first hydraulic cylinder or a hydraulic pump, the integrated electro-hydraulic actuator of the second hydraulic control system is mounted on a second hydraulic cylinder or a hydraulic pump, and the integrated electro-hydraulic actuator of the third hydraulic control system is mounted on a third hydraulic cylinder or a hydraulic pump. The first hydraulic control system is configured to control a movable arm, the second hydraulic control system is configured to control a stick, and the third hydraulic control system is configured to control a bucket. The second hydraulic control system utilizes a three-position four-way electromagnetic switching valve to achieve four-quadrant operation switching of the stick, thereby achieving flow recovery and energy recovery, etc.

[0019]In some embodiments, the movable arm may be controlled by the first hydraulic control system to perform operations such as rising or descending. The stick may be controlled by the second hydraulic control system to perform operations such as extending or retracting. The bucket may be controlled by the third hydraulic control system to perform operations such as digging. The movable arm refers to a drive unit configured on an excavator. The movable arm is mechanically connected to the stick to drive the stick to move. The stick refers to a component on the excavator for controlling the displacement of the bucket. The stick is mechanically connected to the movable arm and the bucket, respectively, to control the displacement and flipping of the bucket. The bucket refers to a component configured on the excavator for digging.

[0020]As shown in FIG. 1 to FIG. 5, the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system includes a secondary pressure regulating transmission control system and a hydraulic power-supply system that provides power for the secondary pressure regulating transmission control system. The secondary pressure regulating transmission control system refers to a control component of the excavator for implementing a hydraulic drive function. A secondary pressure regulating transmission control system 46 includes a first hydraulic control system 43, a second hydraulic control system 44, and a third hydraulic control system 45. Each of the first hydraulic control system 43, the second hydraulic control system 44, and the third hydraulic control system 45 includes an integrated electro-hydraulic actuator. The integrated electro-hydraulic actuator of the first hydraulic control system 43 is independently mounted on a first hydraulic cylinder 1, the integrated electro-hydraulic actuator of the second hydraulic control system 44 is independently mounted on a second hydraulic cylinder 2, and the integrated electro-hydraulic actuator of the third hydraulic control system 45 is independently mounted on a third hydraulic cylinder 3.

[0021]In some embodiments, the hydraulic power-supply system may also be referred to as a hydraulic power-supply control system.

[0022]The first hydraulic control system 43, the second hydraulic control system 44, and the third hydraulic control system 45 refer to systems for performing a hydraulic drive control function.

[0023]The integrated electro-hydraulic actuator refers to an integrated structural unit that implements hydraulic drive control through electrical signals.

[0024]The first hydraulic cylinder 1 is configured to drive the movable arm hydraulically. The second hydraulic cylinder 2 is configured to drive the stick hydraulically. The third hydraulic cylinder 3 is configured to drive the bucket hydraulically.

[0025]In some embodiments, the hydraulic power-supply system 42 includes an energy supply constant pressure pump 29 and a corresponding energy supply electric motor 38, an first energy supply check valve 33, a first energy supply electromagnetic switch switching valve 22 directly connected to a first oil inlet, a second energy supply electromagnetic switch switching valve 23 connected to the energy supply constant pressure pump 29 and an energy supply cooler 36, an energy supply relief valve 27 connected to the second energy supply electromagnetic switch switching valve 23, the energy supply cooler 36 and an energy supply filter 37 connected in series at an inlet of a tank, and a second energy supply check valve 35 directly connected to the inlet of the tank.

[0026]The first energy supply electromagnetic switch switching valve may also be referred to as an energy supply electromagnetic switch switching valve | 22. The second energy supply electromagnetic switch switching valve may also be referred to as an energy supply electromagnetic switch switching valve II 23.

[0027]In some embodiments, the first energy supply electromagnetic switch switching valve 22 is a two-position two-way valve.

[0028]In some embodiments, the energy supply constant pressure pump refers to a pump capable of maintaining a constant outlet pressure. The energy supply constant pressure pump may automatically adjust an operating state so that the outlet pressure always remains at a predetermined value and does not fluctuate drastically due to flow rate changes. The energy supply electric motor 38 is connected to the energy supply constant pressure pump 29 via a coupler (not shown) and is configured to provide electrical energy to drive the energy supply constant pressure pump 29.

[0029]The coupler is a component that connects two rotating shafts. For example, the coupler may connect a rotating shaft of the energy supply electric motor 38 with a rotating shaft of the energy supply constant pressure pump 29.

[0030]In some embodiments, an outlet of the first energy supply electromagnetic switch switching valve 22 may be connected to the first oil inlet C of the first hydraulic control system. An inlet of the first energy supply electromagnetic switch switching valve 22 may be connected to the first energy supply check valve 33.

[0031]In some embodiments, the first energy supply electromagnetic switch switching valve 22 includes two working states including a left position and a right position. The left and right positions refer to two different positions where a valve core is located.

[0032]In some embodiments, when the first energy supply electromagnetic switch switching valve 22 is switched to the left position, the hydraulic oil of the energy supply constant pressure pump 29 is blocked at the first energy supply electromagnetic switch switching valve 22 and cannot flow into the secondary pressure regulating transmission control system. The first energy supply electromagnetic switch switching valve 22 being switched to the left position can ensure that the secondary pressure regulating transmission control system is isolated from the energy supply constant pressure pump 29 when the movable arm, the stick, and the bucket are not operated, improving safety of the system.

[0033]In some embodiments, when an operator issues an instruction to operate the movable arm, the stick, and the bucket, an electromagnet of the first energy supply electromagnetic switch switching valve 22 is energized to switch to the right position. In such cases, the internal oil passage of the first energy supply electromagnetic switch switching valve 22 is completely opened. Hydraulic oil from the energy supply constant pressure pump 29 may flow from a port A of the hydraulic power-supply system into the secondary pressure regulating transmission control system to provide hydraulic power to the movable arm, the stick, and the bucket. When the operation of the movable arm, the stick, and the bucket are completed, the electromagnet is de-energized, and the first energy supply electromagnetic switch switching valve 22 is reset to the left position.

[0034]In some embodiments, the first oil inlet of the first hydraulic control system, a second oil inlet of the second hydraulic control system, and a third oil inlet of the third hydraulic control system are connected to a first port of the hydraulic power-supply system. The first oil outlet of the first hydraulic control system, a second oil outlet of the second hydraulic control system, and a third oil outlet of the third hydraulic control system are connected to a second port of the hydraulic power-supply system.

[0035]The first oil inlet may also be referred to as an oil inlet C. The second oil inlet may also be referred to as an oil inlet E. The third oil inlet may also be referred to as an oil inlet G. The first oil outlet may also be referred to as an oil outlet D. The second oil outlet may also be referred to as an oil outlet F. The third oil outlet is also referred to as an oil outlet H. The first port is also referred to as a port A. The second port is also referred to as a port B.

[0036]The oil inlet C is configured to allow hydraulic oil to flow into the first hydraulic control system. The oil inlet E is configured to allow hydraulic oil to flow into the second hydraulic control system. The oil inlet G is configured to allow hydraulic oil to flow into the third hydraulic control system.

[0037]The oil outlet D is configured to allow hydraulic oil to flow out from the first hydraulic control system. The oil outlet F is configured to allow hydraulic oil to flow out from the second hydraulic control system. The oil outlet H is configured to allow hydraulic oil to flow out from the third hydraulic control system.

[0038]The first port (i.e., port A) and the second port (i.e., port B) are openings of flow pipelines in the hydraulic power-supply system for hydraulic oil to flow in and out. Merely by way of example, the first port (i.e., port A) is configured to allow hydraulic oil to flow out from the hydraulic power-supply system, and the second port (i.e., port B) is configured to allow hydraulic oil to flow into the hydraulic power-supply system.

[0039]In some embodiments, each of the first hydraulic pump, the second hydraulic pump, and the third hydraulic pump is a four-quadrant asymmetrical quantitative hydraulic pump. Each of the first energy supply check valve 33 and the second energy supply check valve 35 is an ordinary check valve. Each of the first energy supply electromagnetic switch switching valve and the second energy supply electromagnetic switch switching valve is a two-position two-way valve. Each of the first electromagnetic switch switching valve I, the first electromagnetic switch switching valve II, the first electromagnetic switch switching valve III, the first electromagnetic switch switching valve IV, the second electromagnetic switch switching valve II, the third electromagnetic switch switching valve I, the third electromagnetic switch switching valve II, and the third electromagnetic switch switching valve Ill is a two-position four-way valve. The second electromagnetic switch switching valve I is a three-position four-way valve.

[0040]The four-quadrant asymmetrical quantitative hydraulic pump refers to a pump-controlled system and is configured to precisely control four operating conditions of the hydraulic cylinder under different loads.

[0041]The two-position two-way valve refers to a valve with two operating states and two ports. The two-position four-way valve refers to a valve with two operating states and four ports. A three-position four-way valve refers to a valve with three operating states and four ports.

[0042]The ordinary check valve refers to a general-purpose valve that controls the opening or closing of a pipeline based on fluid pressure difference. The ordinary check valve can ensure one-way fluid flow and prevent fluid backflow.

[0043]For more descriptions regarding the first energy supply electromagnetic switch switching valve, the second energy supply electromagnetic switch switching valve, the first electromagnetic switch switching valve I, the first electromagnetic switch switching valve II, the first electromagnetic switch switching valve III, the first electromagnetic switch switching valve IV, the second electromagnetic switch switching valve I, the second electromagnetic switch switching valve II, the third electromagnetic switch switching valve I, the third electromagnetic switch switching valve II, and the third electromagnetic switch switching valve III, please refer to FIG. 1 to FIG. 7 and related descriptions below.

[0044]In some embodiments, each of the first hydraulic cylinder, the second hydraulic cylinder, and the third hydraulic cylinder is a single-rod hydraulic cylinder. The first hydraulic cylinder is a hydraulic cylinder of the movable arm, the second hydraulic cylinder is a hydraulic cylinder of the stick, and the third hydraulic cylinder is a hydraulic cylinder of the bucket.

[0045]The single-rod hydraulic cylinder refers to a hydraulic cylinder where a piston rod extends only from one end.

[0046]As shown in FIG. 2, the first hydraulic control system includes a first electromagnetic switch switching valve I 13, a first electromagnetic switch switching valve II 14, a first electric motor 39, a first hydraulic pump 30 driven in coaxial with the first electric motor 39, a first hydraulic cylinder 1 having two chambers respectively connected to the first electromagnetic switch switching valve I 13 and the first electromagnetic switch switching valve II 14, a first pressure sensor I 4 and a first pressure sensor II 5 respectively connected to the two chambers of the first hydraulic cylinder 1, a first electromagnetic switch switching valve III 15 connected to the first electromagnetic switch switching valve I 13, a first electromagnetic switch switching valve IV 16 connected to the first electromagnetic switch switching valve III 15 and connected to the first hydraulic pump 30, and a first relief valve I 24 respectively connected to the first hydraulic pump 30 and connected to the first electromagnetic switch switching valve II 14 and connected to an energy supply cooler I 36.

[0047]In some embodiments, each of the first electromagnetic switch switching valve I 13, the first electromagnetic switch switching valve II 14, the first electromagnetic switch switching valve III 15, and the first electromagnetic switch switching valve IV 16 is a two-position four-way valve.

[0048]In some embodiments, the first electric motor 39 is configured with a generator unit. The first electric motor 39 is also referred to as the first electric motor and the generator unit.

[0049]In some embodiments, the first hydraulic pump 30 is configured with a motor. The first hydraulic pump 30 is also referred to as the first hydraulic pump and the motor.

[0050]In some embodiments, the first electromagnetic switch switching valve I 13, the first electromagnetic switch switching valve II 14, the first electromagnetic switch switching valve III 15, and the first electromagnetic switch switching valve IV 16 all are two-position four-way directional valves and together form a directional control circuit to achieve precise extension and retraction control of the first hydraulic cylinder 1 through coordinated control.

[0051]In some embodiments, the first electromagnetic switch switching valve I 13, the first electromagnetic switch switching valve II 14, the first electromagnetic switch switching valve III 15, and the first electromagnetic switch switching valve IV 16 are energized through electromagnets to switch to the operating state.

[0052]In some embodiments, a direction in which a piston rod of a hydraulic cylinder extends is defined as a positive direction, and a corresponding command speed v>0. A direction in which the piston rod retracts is defined as a negative direction, and a corresponding command speed v<0. In some embodiments, a pressure in a rodless chamber of the hydraulic cylinder is defined as P1, and a pressure in a rod chamber is defined as P2.

[0053]In some embodiments, an impedance extension operating condition refers to an operating state in which the hydraulic cylinder performs an extension motion under an external resistance force. A physical condition corresponding to the impedance extension operating condition includes a command speed v>0 and the pressure in the rodless chamber being greater than the pressure in the rod chamber, i.e., P1>P2.

[0054]In some embodiments, when the first hydraulic control system is utilized to control an action of a movable arm of an excavator, the system has two movable arm operating conditions during movable arm operation, including an impedance extension operating condition or an overrunning retraction operating condition. In some embodiments, the impedance extension operating condition may be classified into an impedance extension heavy-load operating condition and an impedance extension light-load operating condition based on a magnitude of an external load force.

[0055]In some embodiments, the impedance extension operating condition includes a movable arm impedance extension operating condition, a stick impedance extension operating condition, and a bucket impedance extension operating condition.

[0056]In some embodiments, in response to the movable arm rising, a direction of an external load force is opposite to an extension direction of the first hydraulic cylinder 1, a command speed v of the movable arm satisfies v>0, the pressure (i.e., P1) in the rodless chamber and the pressure (i.e., P2) in the rod chamber satisfy P1>P2, and the entire system is in the movable arm impedance extension operating condition. At this time, the hydraulic oil flows out from an outlet of the energy supply constant pressure pump 29, passes through the first energy supply check valve 33, flows into the first electromagnetic switch switching valve V 22 which is fully switched to the right position, then flows into the first electromagnetic switch switching valve IV 16 which is fully switched to the left position through the oil inlet C, and finally flows into the first hydraulic pump 30. In some embodiments, in response to a given constant oil pressure being insufficient to resist the external load force, the first hydraulic pump 30 is in a pumping mode, and the first electric motor 39 is in an electric motor mode and performs secondary pressurization on the hydraulic oil. In some embodiments, in response to the given constant oil pressure being greater than a pressure generated by the external load force, the first hydraulic pump 30 is in a motor mode, and the first electric motor 39 is in a generator mode. In such cases, excess pressure of the hydraulic oil is recovered. The hydraulic oil flows out from the first hydraulic pump 30, then passes through the first electromagnetic switch switching valve I 13 which is fully switched to the left position, and finally flows into the oil inlet of the rodless chamber of the first hydraulic cylinder 1. The returned hydraulic oil flows out from the oil outlet of the rod chamber, passes through the first electromagnetic switch switching valve II 14 which is fully switched to the left position, flows out from the oil outlet D, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank. In some embodiments, the first relief valve I 24 can prevent damage to the system caused by excessive pressure in the pipeline circuit, ensuring the safety of the pipeline circuit.

[0057]In some embodiments, in response to the movable arm descending, the direction of the external load force is the same as a contraction direction of the first hydraulic cylinder 1, the entire system is in the overrunning retraction operating condition. The command speed v of the movable arm satisfies v<0, and the pressure (i.e., P1) in the rodless chamber and the pressure (i.e., P2) in the rod chamber satisfy P1>P2. The first hydraulic pump 30 is in the motor mode, the first electric motor 39 is in the generator mode, and energy of the system is recovered. The hydraulic oil flows out from the oil outlet of the rodless chamber, passes through the first electromagnetic switch switching valve I 13 which is fully switched to the left position, then flows into the first hydraulic pump 30, and finally flows through the first electromagnetic switch switching valve IV 16 which is fully switched to the right position. After the hydraulic oil flows through the first electromagnetic switch switching valve IV 16 which is fully switched to the right position, a portion of the hydraulic oil flows through the first electromagnetic switch switching valve II 14 which is fully switched to the left position, and then flows back to the rod chamber of the first hydraulic cylinder 1. Another portion of the hydraulic oil flows out from the oil outlet D, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank. In some embodiments, the first relief valve I 24 can prevent damage to the system caused by excessive pressure in the pipeline circuit, ensuring the safety of the pipeline circuit.

[0058]In some embodiments, the second hydraulic control system includes a second electromagnetic switch switching valve I 10, a second electric motor 40, a second hydraulic pump 31 driven in coaxial with the second electric motor 40, the second hydraulic cylinder 2 with two chambers connected to the second electromagnetic switch switching valve I 10, a second pressure sensor I 6 and a second pressure sensor II 7 respectively connected to the two chambers of the second hydraulic cylinder 2, a second electromagnetic switch switching valve II 17 connected to the second hydraulic pump 31, and a second relief valve I 25 connected to the second hydraulic pump 31 and a second oil outlet F.

[0059]The second hydraulic pump 31 is configured to pressurize hydraulic oil in the second hydraulic cylinder 2 and related flow pipelines. The system controls the flow of the hydraulic oil in the flow pipelines by controlling opening and closing of the second electromagnetic switch switching valve II 17.

[0060]In some embodiments, since the second hydraulic pump 31 needs to be converted into a motor to recover energy when the system is in an overrunning operating condition, the second hydraulic pump 31 does not pressurize the hydraulic oil.

[0061]In some embodiments, the second electromagnetic switch switching valve II 17 is the two-position four-way valve, and the second electromagnetic switch switching valve I 10 is the three-position four-way valve.

[0062]In some embodiments, the second electromagnetic switch switching valve II 17 includes two working states including a left position and a right position. The second electromagnetic switch switching valve I 10 includes three working states including a left position, a neutral position, and a right position. The left, neutral, and right positions refer to different positions where a valve core is located. In some embodiments, the neutral position may be when the valve is in a holding state, and placing the valve in the neutral position can help maintain the load.

[0063]In some embodiments, the function of one three-position four-way valve may be equivalent to the function of two two-position four-way valves. The four types of stick operation conditions that exist in the system when the stick is working can be realized through the three-position four-way valve.

[0064]In some embodiments, the second electric motor 40 is configured with a generator unit. The second electric motor 40 is also referred to as the second electric motor and the generator unit.

[0065]In some embodiments, the second hydraulic pump 31 is configured with a motor. The second hydraulic pump 31 is also referred to as the second hydraulic pump and the motor.

[0066]In some embodiments, in response to utilizing the second hydraulic control system to control an action of a stick of an excavator, the system has four stick operating conditions during stick operation, including an impedance extension operating condition, an impedance retraction operating condition, an overrunning extension operating condition, and an overrunning retraction operating condition.

[0067]In some embodiments, the second electromagnetic switch switching valve I 10 and the second electromagnetic switch switching valve II 17 are controlled by the system to energize the electromagnets, so as to switch to the operating state.

[0068]In some embodiments, when the second hydraulic cylinder 2 extends outside, a direction of an external load force is opposite to an extension direction of the second hydraulic cylinder 2, a command speed v of the stick satisfies v>0, the pressure in the rodless chamber and the pressure in the rod chamber satisfy P1>P2, and the system is in the stick impedance extension operating condition. In such cases, the hydraulic oil firstly flows out from an outlet of the energy supply constant pressure pump 29, then flows into the oil inlet E through the first energy supply check valve 33, then flows into the second hydraulic pump 31 through the second electromagnetic switch switching valve II 17 fully switched to the right position, and finally flows into the rodless chamber of the second hydraulic cylinder 2 through the second electromagnetic switch switching valve I 10 fully switched to the left position to push a piston to extend out. In some embodiments, in response to a given constant oil pressure being insufficient to resist the external load force, the second hydraulic pump 31 is in a pumping mode, and the second electric motor 40 is in an electric motor mode and performs secondary pressurization on the hydraulic oil. In some embodiments, in response to the given constant oil pressure being greater than a pressure generated by the external load force, the second hydraulic pump 31 is in a motor mode, and the second electric motor 40 is in a generator mode to recover excess hydraulic oil. In such cases, the hydraulic oil flows out from the second hydraulic pump 31, then passes through the second electromagnetic switch switching valve I 10 which is fully switched to the left position, and finally flows into the oil inlet of the rodless chamber of the second hydraulic cylinder 2. The returned hydraulic oil flows out from the oil outlet of the rod chamber of the second hydraulic cylinder 2, passes through the second electromagnetic switch switching valve I 10 which is fully switched to the left position, flows out from the oil outlet F, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank. In some embodiments, the second relief valve I 25 acts as a safeguard for the pipeline circuit. In some embodiments, in response to the second hydraulic cylinder 2 extending outside, the direction of the external load force is the same as the extension direction of the second hydraulic cylinder 2, the command speed v of the stick satisfies v<0, the pressure in the rodless chamber and the pressure in the rod chamber satisfy P1<P2, the system is in the overrunning extension operating condition, the second hydraulic pump 31 is in the motor mode, and the second electric motor 40 is in the generator mode to recover gravitational potential energy of the stick. In such cases, the hydraulic oil flows out from the oil outlet of the rod chamber of the second hydraulic cylinder 2, flows through the second electromagnetic switch switching valve I 10 which is fully switched to the right position, flows through the second hydraulic pump 31, then flows through the second electromagnetic switch switching valve II 17 which is fully switched to the left position, and finally flows back to the rodless chamber of the second hydraulic cylinder 2. In some embodiments, the second relief valve I 25 acts as a safeguard for the pipeline circuit to prevent damage to the system caused by excessive pressure in the pipeline circuit.

[0069]In some embodiments, in response to the second hydraulic cylinder 2 retracting, the direction of the external load force is opposite to the extension direction of the second hydraulic cylinder 2, the command speed v of the stick satisfies v<0, the pressure in the rodless chamber and the pressure in the rod chamber satisfy P1<P2, and the system is in the impedance retraction operating condition. In such cases, the hydraulic oil flows out from the outlet of the energy supply constant pressure pump 29, flows through the first energy supply check valve 33, flows into the oil inlet E, flows through the second electromagnetic switch switching valve II 17 which is fully switched to the right position, flows into the second hydraulic pump 31, then flows through the second electromagnetic switch switching valve I 10 which is fully switched to the right position, and finally flows into the rod chamber of the second hydraulic cylinder 2 to push the piston to contract. In some embodiments, in response to the given constant oil pressure being insufficient to resist the external load force, the second hydraulic pump 31 is in the pumping mode, and the second electric motor 40 is in the electric motor mode and performs secondary pressurization on the hydraulic oil. In some embodiments, in response to the given constant oil pressure being greater than the pressure generated by the external load force, the second hydraulic pump 31 is in the motor mode, and the second electric motor 40 is in the generator mode to recover excess pressure of the hydraulic oil. In such cases, the hydraulic oil flows out from the second hydraulic motor, flows through the second electromagnetic switch switching valve I 10 which is fully switched to the right position, and finally flows into the oil inlet of the rod chamber of the second hydraulic cylinder 2. The returned hydraulic oil flows out from the oil outlet of the rodless chamber, flows through the second electromagnetic switch switching valve I 10 which is fully switched to the right position, flows through the oil outlet F, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank. In some embodiments, the second relief valve I 25 acts as a safeguard for the pipeline circuit.

[0070]In some embodiments, in response to the second hydraulic cylinder 2 retracting, the direction of the external load force is the same as the extension direction of the second hydraulic cylinder 2, the command speed v of the stick satisfies v<0, the pressure in the rodless chamber and the pressure in the rod chamber satisfy P1>P2, the system is in the overrunning retraction operating condition, the second hydraulic pump 31 is in the motor mode, and the second electric motor 40 is in the generator mode to recover gravitational potential energy of the stick. In such cases, the hydraulic oil flows out from the oil outlet of the rodless chamber of the second hydraulic cylinder 2, flows through the second electromagnetic switch switching valve I 10 which is fully switched to the left position, then flows through the hydraulic pump 31, and finally flows through the second electromagnetic switch switching valve II 17 which is fully switched to the left position. After the hydraulic oil flows through the second electromagnetic switch switching valve II 17 which is fully switched to the left position, a portion of the hydraulic oil flows through the second electromagnetic switch switching valve I 10 which is fully switched to the left position, and then flows into the rod chamber of the second hydraulic cylinder 2. Another portion of the hydraulic oil flows out from the oil outlet F, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank. In some embodiments, the second relief valve I 25 acts as a safeguard for the pipeline circuit to prevent damage to the system caused by excessive pressure in the pipeline circuit.

[0071]In some embodiments, the third hydraulic control system includes a third electromagnetic switch switching valve I 19, a third electric motor 41, a third hydraulic pump 32 driven coaxial with the third electric motor 41, a third electromagnetic switch switching valve II 20, a third hydraulic cylinder 3 with two chambers respectively connected to the third electromagnetic switch switching valve I 19 and the third electromagnetic switch switching valve II 20, a third pressure sensor I 8 and a third pressure sensor II 9 respectively connected to the two chambers of the third hydraulic cylinder 3, a third electromagnetic switch switching valve III 21 directly connected to an oil inlet of the third hydraulic pump 32, and a third relief valve I 26 connected to an oil outlet of the third hydraulic pump 32 and the oil outlet H.

[0072]The third hydraulic pump 32 is configured to pressurize the hydraulic oil in the third hydraulic cylinder 3 and in related flow pipelines. The system controls the flow of the hydraulic oil in the flow pipelines by controlling opening and closing of the third electromagnetic switch switching valve I 19, the third electromagnetic switch switching valve II 20, and the third electromagnetic switch switching valve III 21. For example, the system enables the hydraulic oil to flow into the third hydraulic pump 32 by opening the third electromagnetic switch switching valve III 21.

[0073]In some embodiments, since the third hydraulic pump 32 needs to be converted into a motor to recover energy when the system is in an overrunning operating condition, the third hydraulic pump 32 does not pressurize the hydraulic oil.

[0074]In some embodiments, each of the third electromagnetic switch switching valve I 19, the third electromagnetic switch switching valve II 20, and the third electromagnetic switch switching valve III 21 is the two-position four-way valve.

[0075]In some embodiments, the third electric motor 41 is configured with a generator unit. The third electric motor 41 is also referred to as the third electric motor and the generator unit.

[0076]In some embodiments, the third hydraulic pump 32 is configured with a motor. The third hydraulic pump 32 is also referred to as the third hydraulic pump and the motor.

[0077]In some embodiments, in response to utilizing the third hydraulic control system to control an action of the bucket of the excavator, the system has two operating conditions during bucket operation, including an impedance extension operating condition and an overrunning retraction operating condition.

[0078]In some embodiments, during an excavating process of the bucket, in response to the third hydraulic cylinder 3 being in an extended state, the direction of the external load force is opposite to an extension direction of the third hydraulic cylinder 3, a command speed v of the bucket satisfies v>0, the pressure in the rodless chamber and the pressure in the rod chamber satisfy P1>P2, and the system is in a bucket impedance extension operating condition. In such cases, the hydraulic oil flows out from the outlet of the energy supply constant pressure pump 29, flows through the first energy supply check valve 33, flows through the oil inlet G, then flows into the third electromagnetic switch switching valve III 21 which is fully switched to the left position, and finally flows into the third hydraulic pump 32. In some embodiments, in response to the given constant oil pressure being insufficient to resist the external load force, the third hydraulic pump 32 is in the pumping mode, and the third electric motor 41 is in the electric motor mode and performs secondary pressurization on the hydraulic oil. In some embodiments, in response to the given constant oil pressure being greater than a pressure generated by the external load force, the third hydraulic pump 32 is in the motor mode, and the third electric motor 41 is in the generator mode to recover excess pressure of the hydraulic oil. In such cases, the hydraulic oil flows out from the third hydraulic pump 32, then flows through the third electromagnetic switch switching valve I 19 which is fully switched to the left position, and finally flows into an oil inlet of the rodless chamber of the third hydraulic cylinder 3. The returned hydraulic oil flows out from an oil outlet of the rod chamber, flows through the third electromagnetic switch switching valve II 20 which is fully switched to the left position, flows out from the oil outlet H, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank from the oil inlet B. In some embodiments, the third relief valve I 26 acts as a safeguard for the pipeline circuit to prevent damage to the system caused by excessive pressure in the pipeline circuit.

[0079]In some embodiments, during a unloading process of the bucket, in response to the third hydraulic cylinder 3 being in a retracted state, the direction of the external load force is the same as a retraction direction of the third hydraulic cylinder 3, the system is in the overrunning retraction operating condition, the third hydraulic pump 32 is in the motor mode, and the third electric motor 41 is in the generator mode to recover energy of the system. In such cases, the hydraulic oil flows out from the oil outlet of the rodless chamber, flows through the third electromagnetic switch switching valve I 19 which is fully switched to the left position, then flows through the third hydraulic pump 32, and finally flows through the third electromagnetic switch switching valve III 21 which is fully switched to the right position. After the hydraulic oil flows through the third electromagnetic switch switching valve III 21 which is fully switched to the right position, a portion of the hydraulic oil flows through the third electromagnetic switch switching valve II 20 which is fully switched to the left position, and then flows into the rod chamber of the third hydraulic cylinder 3. Another portion of the hydraulic oil flows out from the oil outlet H, then flows through the energy supply cooler I 36 and the energy supply filter I 37 respectively, and finally flows back to the tank from the oil inlet B. In some embodiments, the third relief valve I 26 acts as a safeguard for the pipeline circuit to prevent damage to the system caused by excessive pressure in the pipeline circuit.

[0080]In some embodiments, when the system is in the overrunning retraction operating condition, as described above for the overrunning retraction operating condition of the bucket, the returned hydraulic oil may also be divided into two portions. One portion of the hydraulic oil flows back to the rod chamber of the hydraulic cylinder, and the other portion flows back to the tank from the outlet.

[0081]In some embodiments, the energy supply relief valve 27 in the hydraulic power-supply system may serve as a safety valve to ensure system safety. The purpose is to prevent damage to the system caused by excessive pressure in the pipeline circuit. The first energy supply check valve 33 may act as a safeguard for the pipeline circuit to prevent damage to the energy supply constant pressure pump 29 caused by the backflow of hydraulic oil. The energy supply cooler I 36 may cool the hydraulic oil to prevent the oil temperature from being too high to affect the working efficiency of the system. The energy supply filter I 37 may filter the hydraulic oil of the system to ensure the purity of the hydraulic oil. In some embodiments, when the energy supply constant pressure pump 29 is operating, the second energy supply electromagnetic switch switching valve 23 may be opened to cool and filter the hydraulic oil in the tank more comprehensively and efficiently. The second energy supply check valve III 35 mainly serves the functions of exhausting air.

[0082]In some embodiments, the working principle of the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system is as follows. Based on a basic pressure set by the energy supply constant pressure pump, the pressure sensor I and the pressure sensor II respectively collect pressures of two chambers of the hydraulic cylinder (including the pressure P1 in the rodless chamber and the pressure P2 in the rod chamber). A current operating mode of the system is determined by combining an actuator command speed v. The command speed v is set with an extension direction of the hydraulic cylinder as the positive direction. A load force F is set with a contraction direction of the hydraulic cylinder as the positive direction. Thus, a control in the four-quadrant operation mode is achieved. The actuator command speed v refers to a parameter used to determine the operating mode of the hydraulic cylinder.

[0083]In some embodiments, the constant pressure control of the energy supply constant pressure pump adopts a composite control manner combining flow feedforward and pressure feedback. The flow feedforward simultaneously considers the volumetric efficiency of the primary main pump and the secondary pump unit as well as the leakage amount of the hydraulic cylinder to determine a required rotational speed signal for the energy supply constant pressure pump, thereby improving the control response. The pressure feedback control loop determines a difference between a predetermined pressure of the pump and an outlet pressure. A compensation amount for the rotational speed signal of the motor is obtained through a PID regulator, so as to correct calculation errors of the flow feedforward under a time-varying uncertain operating condition, thereby improving control accuracy. The PID regulator refers to a proportional-integral-derivative controller.

[0084]In some embodiments, a rotational speed signal U_m0 of the energy supply electric motor is shown in formula (1):

[0086]In some embodiments, the pressure difference P_e may be expressed as formula (2):

[0088]A rotational speed signal in the flow feedforward compensation stage is shown in formula (3):

[0090]A pressure feedback control signal used by the PID regulator is shown in formula (4):

[0092]The pressure feedback control signal refers to a correction signal used to adjust the rotational speed of the energy supply electric motor based on a pressure difference.

[0093]The proportional coefficient, the integral coefficient, and the differential coefficient are three parameters in the PID regulator, which are used to adjust the response degree of the PID regulator to an error to achieve precise control of the rotational speed of the hydraulic cylinder.

[0094]In some embodiments, the proportional coefficient, the integral coefficient, and the differential coefficient may be values predetermined by a user.

[0095]In some embodiments, a processor may determine a current operating mode of the excavator, and determine the proportional coefficient, the integral coefficient, and the differential coefficient corresponding to the pressure feedback control signal according to the current operating mode.

[0096]For more descriptions on determining the proportional coefficient, the integral coefficient, and the differential coefficient, please refer to FIG. 7 and the related descriptions.

[0097]In some embodiments, in response to an actuator of the first hydraulic control system being a movable arm hydraulic cylinder, a process for determining the pressure feedback control signal is as follows.

[0098]In some embodiments, in response to the actuator command speed v satisfying v>0 and the pressure in the rodless chamber and the pressure in the rod chamber satisfying P₁>P₂, the system is in a movable arm impedance extension operating condition, the first hydraulic pump in the first hydraulic control system is in the pumping mode and operates together with the energy supply constant pressure pump of the hydraulic power-supply control system. The energy supply constant pressure pump outputs a given constant pressure value, and the first hydraulic pump serves a secondary pressure boosting function. A rotational speed signal n, of the first electric motor is shown in formula (5):

[0100]In response to the actuator command speed v satisfying v<0 and the pressure in the rodless chamber and the pressure in the rod chamber satisfying P₁>P₂, the system is in an overrunning retraction operating condition, and the first hydraulic pump in the first hydraulic control system is in the motor mode. The rotational speed signal n_r of the first electric motor is shown in formula (6):

[0102]In some embodiments, in response to the actuator of the second hydraulic control system being the stick hydraulic cylinder, the process for determining the pressure feedback control signal is as follows.

[0103]In response to the actuator command speed v satisfying v>0 and the pressure in the rodless chamber and the pressure in the rod chamber satisfying P₁>P₂, the system is in the stick impedance extension operating condition, the second electromagnetic switch switching valve I 10 is fully switched to the left position, and the second hydraulic pump in the second hydraulic control system is in the pumping mode and operates together with the energy supply constant pressure pump of the hydraulic power-supply control system. The energy supply constant pressure pump outputs the given constant pressure value, and the second hydraulic pump serves the secondary pressure boosting function. The rotational speed signal of the second electric motor is shown in formula (7):

[0105]In response to the actuator command speed v satisfying v>0 and the pressure in the rodless chamber and the pressure in the rod chamber satisfying P₁<P₂, the system is in the overrunning extension operating condition, and the second hydraulic pump in the second hydraulic control system is in the motor mode. The rotational speed signal of the second electric motor is shown in formula (8):

[0107]In response to an actuator command speed v satisfying v<0 and pressures at the oil inlet and oil outlet of the actuator satisfying P₁>P₂, the system is in the overrunning retraction operating condition, and the second hydraulic pump in the second hydraulic control system is in the motor mode. The rotational speed signal of the second electric motor is shown in formula (9):

[0109]In response to the actuator command speed v satisfying v<0 and the pressure in the rodless chamber and the pressure in the rod chamber satisfying P₁<P₂, the system is in the impedance retraction operating condition, and the second hydraulic pump in the second hydraulic control system is in the pumping mode and operates together with the energy supply constant pressure pump of the hydraulic power-supply control system. The energy supply constant pressure pump outputs the given constant pressure value, and the second hydraulic pump serves the secondary pressure boosting function. The rotational speed signal of the second electric motor is shown in formula (10):

[0111]In some embodiments, in response to the actuator of the third hydraulic control system being the bucket hydraulic cylinder, the process for determining the pressure feedback control signal is as follows.

[0112]In response to the actuator command speed v satisfying v>0, and the pressure in the rodless chamber and the pressure in the rod chamber satisfy P₁>P₂, the system is in the impedance extension operating condition, and the third hydraulic pump in the third hydraulic control system is in the pumping mode and operates together with the energy supply constant pressure pump of the hydraulic power-supply system. The energy supply constant pressure pump outputs the given constant pressure value. The third hydraulic pump serves the secondary pressure boosting function. A rotational speed signal of the third electric motor driven by the third hydraulic pump is shown in formula (11):

[0114]In response to the actuator command speed v satisfying v<0, and the pressures at the oil inlet and oil outlet of the actuator satisfying P₁>P₂, the system is in the overrunning retraction operating condition, and the third hydraulic pump in the third hydraulic control system is in the motor mode. The rotational speed signal of the third electric motor is shown in formula (12):

[0116]In some embodiments, the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system further includes a processor.

[0117]In some embodiments, the processor may include a central processing unit (CPU), a graphics processing unit (GPU), a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), etc. In some embodiments, the processor may be configured for data processing, issuing control signals, etc.

[0118]In some embodiments, the processor may be configured in the secondary pressure regulating transmission control system. Merely by way of example, the processor may include three sub-processors. The three sub-processors are in the first hydraulic control system, the second hydraulic control system, and the third hydraulic control system, respectively.

[0119]In some embodiments, the processor is configured to determine, by performing a prediction process, a first leakage coefficient C_q1 of each of the first hydraulic cylinder 1, the second hydraulic cylinder 2, and the third hydraulic cylinder 3, and a second leakage coefficient C_q2 and a volumetric efficiency no of each of the first hydraulic pump 30, the second hydraulic pump 31, the third hydraulic pump 32, and the energy supply constant pressure pump 29.

[0120]The first leakage coefficient refers to a value characterizing a leakage degree of a hydraulic cylinder of an excavator. The first leakage coefficient may include three coefficients. The leakage coefficients correspond to the first hydraulic cylinder 1, the second hydraulic cylinder 2, and the third hydraulic cylinder 3, respectively.

[0121]The second leakage coefficient refers to a value characterizing a leakage degree of a pump of an excavator. The first hydraulic pump 30, the second hydraulic pump 31, the third hydraulic pump 32, and the energy supply constant pressure pump 29 each correspond to a leakage coefficient.

[0122]The volumetric efficiency refers to a ratio of a flow rate of the hydraulic oil to an ideal flow rate (e.g., a flow rate without leakage) when the first hydraulic pump 30, the second hydraulic pump 31, the third hydraulic pump 32, and the energy supply constant pressure pump 29 are operating.

[0123]For more descriptions regarding the first leakage coefficient, the second leakage coefficient, and the volumetric efficiency, please refer to the related descriptions above.

[0124]In some embodiments, the processor may perform the prediction process in a plurality of ways (e.g., calculation, fitting, statistical analysis, etc.).

[0125]FIG. 6 is a schematic diagram illustrating an exemplary parameter prediction model according to some embodiments of the present disclosure.

[0126]As shown in FIG. 6, the processor is configured to construct a hydraulic topology map 610, and predict a first leakage coefficient 630, a second leakage coefficient 640, and a volumetric efficiency 650 using a parameter prediction model 620 based on the hydraulic topology map 610.

[0127]The parameter prediction model refers to a model configured to determine the first leakage coefficient, the second leakage coefficient, and the volumetric efficiency. The parameter prediction model may be a graph neural networks (GNN) model, or other customized model structure, etc., or any combination thereof.

[0128]The hydraulic topology map 610 refers to a graph reflecting connectivity relationships of structures such as hydraulic cylinders and hydraulic pumps. In some embodiments, the hydraulic topology map including nodes 611 and edges 612, the nodes 611 including hydraulic cylinder nodes, pump nodes, electromagnetic valve nodes, etc., the edges 612 representing flow pipelines for the hydraulic oil between the nodes. The nodes 611 refer to virtual elements constructed based on actual structures such as hydraulic cylinders and hydraulic pumps. An edge represents an association or connection between nodes. The edge is a directed edge, and a direction represents a flow direction of the hydraulic oil.

[0129]In some embodiments, node attributes of hydraulic cylinder nodes include a rodless chamber cross-sectional area, a rod chamber cross-sectional area, a displacement, a cylinder diameter, a real-time speed, a pressure difference, etc. Node attributes of pump nodes include a rated displacement, a rated rotational speed, a real-time temperature, a real-time motor rotational speed, a real-time torque, etc. Node attributes of electromagnetic valve nodes include a valve switch status. The rodless chamber cross-sectional area, the rod chamber cross-sectional area, the displacement, the cylinder diameter, the rated displacement, and the rated rotational speed may be determined by measurement or by querying models of the hydraulic cylinders or the hydraulic pumps, etc. The real-time speed, the pressure difference, the real-time temperature, the real-time motor rotational speed, and the real-time torque may be determined by collecting data from sensors (e.g., a temperature sensor, a pressure sensor, etc.). The valve switch status may be determined by communicating with the electromagnetic valve.

[0130]In some embodiments, the processor may perform a graph structure abstraction on the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system, and construct the hydraulic topology map based on physical topology relationships of various structural units in the system. The physical topology relationships may be determined by the processor based on excavator-related hardware and corresponding flow pipelines of the hydraulic oil.

[0131]In some embodiments, the hydraulic topology map may further include tank nodes and pressure measurement point nodes representing pipeline intersection points, etc. The tank nodes and the pressure measurement point nodes may be constructed according to structures and connection relationships in the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system.

[0132]In some embodiments, edges of the hydraulic topology map are constructed according to hydraulic structures of the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system. Merely by way of example, in response to an oil circuit connection existing between the first hydraulic pump 30 and the first electromagnetic switch switching valve IV 16, a corresponding edge is constructed in the hydraulic topology map.

[0133]In some embodiments, edge attributes include a pipeline length and a pipeline diameter of a flow pipeline of the hydraulic oil and a real-time fluid flow speed of the hydraulic oil, etc. The pipeline length and the pipeline diameter may be obtained by measurement. The real-time fluid flow speed may be determined by collecting data from a speed sensor.

[0134]In some embodiments, the node attributes corresponding to the hydraulic cylinder nodes and the pump nodes include cumulative working hours.

[0135]The cumulative working hours refer to a total time that the corresponding hydraulic cylinder or the hydraulic pump has worked or operated. The cumulative working hours may be determined by a timer. In some embodiments, by using the cumulative working hours as a node attribute of the hydraulic cylinder nodes and/or the pump nodes and training the parameter prediction model, the parameter prediction model may be helped to understand a long-term impact of component wear on leakage and efficiency.

[0136]In some embodiments, the processor may input the hydraulic topology map into the parameter prediction model and obtain a first leakage coefficient C_q1 of each of the first hydraulic cylinder, the second hydraulic cylinder, and the third hydraulic cylinder, and a second leakage coefficient C_q2 and a volumetric efficiency η₀ of each of the first hydraulic pump, the second hydraulic pump, the third hydraulic pump, and the energy supply constant pressure pump output by the parameter prediction model.

[0137]In some embodiments, the parameter prediction model may be obtained by the processor through model training based on at least one set of first training samples and corresponding first labels. A first training sample includes a sample hydraulic topology map. A first label corresponding to the first training sample includes a sample first leakage coefficient C_q1 of each of a sample first hydraulic cylinder, a sample second hydraulic cylinder, and a sample third hydraulic cylinder, and a sample second leakage coefficient C_q2 and a sample volumetric efficiency η₀ of each of a sample first hydraulic pump, a sample second hydraulic pump, a sample third hydraulic pump, and a sample energy supply constant pressure pump.

[0138]In some embodiments, the first training samples may be constructed based on historical data or experimental data, and the first labels corresponding to the first training samples may be generated and annotated through data collection. Merely by way of example, on an excavator equipped with sensors, tests under full operating conditions are performed based on combinations of parameters, such as different real-time motor rotational speeds, different real-time temperatures, different real-time speeds, etc. Data corresponding to the attributes of the aforementioned nodes and the attributes of the edges is collected. Real leakage coefficients and real volumetric efficiencies of various structures or components are synchronously recorded to serve as the first labels. The real leakage coefficients and the real volumetric efficiencies are determined based on collecting data from sensors. The sensors may include a flow meter, a pressure sensor, a speed sensor, a temperature sensor, etc.

[0139]In some embodiments, the model training includes offline training a graph neural network model based on a large count of collected data. The offline training includes enabling the graph neural network model to learn a complex nonlinear mapping relationship from an input graph structure to an output first leakage coefficient C_q1 of each of the first hydraulic cylinder, the second hydraulic cylinder, and the third hydraulic cylinder, and an output second leakage coefficient C_q2 and an output volumetric efficiency η₀ of each of the first hydraulic pump, the second hydraulic pump, the third hydraulic pump, and the energy supply constant pressure pump.

[0140]During the model training, the first training samples are input into an initial parameter prediction model, a loss function is constructed based on outputs of the initial parameter prediction model and the first labels. Parameters of the initial parameter prediction model are iteratively updated based on the loss function until a predetermined training condition is met, at which point the training ends and a trained parameter prediction model is obtained. The predetermined training condition may include, but is not limited to, convergence of the loss function, a training cycle reaching a threshold, etc. The manners for the iterative updating may include a gradient descent technique, a simulated annealing algorithm, etc.

[0141]In some embodiments, in response to a current operating mode of a current excavator being a crushing hammer mode, the input of the parameter prediction model further includes impact features. The current excavator refers to an excavator that is currently in operation. The current operating mode is an operating mode in which the current excavator is currently operating.

[0142]The operating mode is one of a plurality of predefined operating conditions of the excavator. Merely by way of example, the operating mode includes a digging cycle mode, a leveling operating mode, a loading operating mode, the crushing hammer mode, a fine manipulation mode, a fast no-load slewing mode, etc.

[0143]The current operating mode refers to an operating mode in which the current excavator is currently operating.

[0144]The crushing hammer mode refers to an operating mode in which the excavator performs a crushing operation by installing a crushing hammer.

[0145]The impact features refer to features related to impacts and vibrations generated during the operating process of the excavator. The impact feature may include an impact intensity and an impact frequency. The impact intensity may reflect a force magnitude of each strike of the crushing hammer and the hardness of a crushed object. The impact frequency may reflect a count of strikes per minute of the crushing hammer.

[0146]In some embodiments, the processor may collect a pressure signal or a vibration signal corresponding to the impact feature based on a pressure sensor mounted on the bucket, and through an acceleration sensor or a vibration sensor mounted at an end of the stick, etc.

[0147]In some embodiments, the processor may determine a main frequency peak as the impact frequency by performing a Fast Fourier Transform (FFT) on the pressure signal or the vibration signal.

[0148]In some embodiments, the processor may determine the impact intensity by determining a peak value or a root mean square value of the pressure signal or the vibration signal, or an amplitude of a main frequency in an energy spectrum.

[0149]In some embodiments, in response to the current operating mode of the current excavator being the crushing hammer mode, the processor may dynamically inject the impact features into attributes of graph nodes related to the crushing hammer. The graph nodes related to the crushing hammer may include hydraulic cylinder nodes and pump nodes corresponding to the bucket.

[0150]In some embodiments, when the input of the parameter prediction model includes the impact feature, the first training samples may further include a sample impact feature.

[0151]In some embodiments, by inputting the impact feature into the parameter prediction model, the parameter prediction model may more effectively learn and quantify a physical correlation between the impact intensity/the impact frequency and the leakage coefficient/the volumetric efficiency.

[0152]An impact may cause transient deformation of a sealed member and periodic destruction of an oil film, leading to compression and expansion effects of the hydraulic oil, leading to dynamic leakage. By utilizing the impact feature as an input of the parameter prediction model, this dynamic leakage, which is ignored in conventional models, can be accurately predicted, thereby outputting the leakage coefficients and the volumetric efficiencies with high precision that better conform to actual operating conditions of the impact.

[0153]In some embodiments, by training and applying the parameter prediction model, the system may efficiently determine the leakage coefficients and/or the volumetric efficiencies of different hydraulic cylinders or hydraulic pumps that conform to reality.

[0154]FIG. 7 is a flowchart illustrating an exemplary process for determining a proportional coefficient, an integral coefficient, and a differential coefficient corresponding to a pressure feedback control signal according to some embodiments of the present disclosure. As shown in FIG. 7, a process 700 includes the following steps. The process 700 may be performed by the processor.

[0155]In 710, a motion trajectory and a pressure sensing sequence of each of the movable arm, the stick, and the bucket within a predetermined time period may be obtained. For more description regarding the movable arm, the stick, and the bucket, please refer to FIG. 1 to FIG. 5 above and related descriptions.

[0156]The predetermined time period refers to a pre-set time period that may be dynamically updated (e.g., the predetermined time period may be 10 seconds, etc.).

[0157]In some embodiments, the processor may preset the predetermined time period in advance based on user settings.

[0158]In some embodiments, the processor may determine a length of the predetermined time period based on a system activity level.

[0159]The system activity level refers to a value reflecting an operating intensity of the excavator and/or a switching frequency of the operating state of the excavator. The greater the operating intensity of the excavator and/or a more frequent switching of the operating state, the greater the system activity level.

[0160]In some embodiments, the processor may determine the system activity level through a plurality of manners (e.g., calculation, statistical analysis, etc.).

[0161]In some embodiments, the processor may determine the system activity level based on pressure signals of the first hydraulic cylinder, the second hydraulic cylinder, and the third hydraulic cylinder and the flow rates of the hydraulic oil. For example, the processor may convert an absolute value of a product of the pressure signal and the flow rate of the hydraulic oil for each hydraulic cylinder at a certain moment into a dimensionless value through normalization processing and then perform summation on the dimensionless values to obtain the system activity level. The flow rate of the hydraulic oil may be determined by collecting data from a flow meter. For more descriptions regarding the first hydraulic cylinder, the second hydraulic cylinder, and the third hydraulic cylinder, please refer to FIG. 1 to FIG. 5 and related descriptions.

[0162]Merely by way of example, when the excavator is performing heavy-duty digging or rapid movement, both pressure and flow rate are large, and the system activity level is a high value. When the excavator is moving without a load or performing fine adjustments, the pressure or flow rate is small, and the system activity level is a low value. When the excavator is idling or stationary, the system activity level is close to zero.

[0163]In some embodiments, the length of the predetermined time period is negatively correlated with the system activity level. The larger the system activity level, the shorter the length of the predetermined time period.

[0164]In some embodiments, when the system activity level is large, it indicates that the system is currently in a high-intensity and rapidly dynamically changing operating state (e.g., digging, rapid slewing, etc.). In high-intensity operations, the operating mode may switch frequently. Setting a shorter predetermined time period to quickly capture operation changes may improve the response speed of the system.

[0165]The motion trajectory refers to data reflecting movement conditions of the movable arm, the stick, and the bucket of the excavator during operation. For example, the motion trajectory may include position-time sequences of moving directions, rotation angles, moving distances, etc., of the movable arm, the stick, and the bucket at different moments.

[0166]The pressure sensing sequence refers to a pressure-time sequence reflecting pressures to connect two chambers of the hydraulic cylinders where the movable arm, the stick, and the bucket of the excavator are located.

[0167]In some embodiments, the processor may continuously collect and store data within the predetermined time period at a fixed sampling frequency (e.g., 50 Hz, etc.) through sensors and/or components (e.g., a gyroscope, an acceleration sensor, a pressure sensor, etc.) deployed on the movable arm, the stick, and the bucket.

[0168]In some embodiments, the processor collects position sensor data of the hydraulic cylinders of the movable arm, the stick, and the bucket at different moments to form a plurality of sets of position-time sequences, and determines the plurality of sets of position-time sequences as the motion trajectories.

[0169]In some embodiments, the motion trajectory includes speed and acceleration information. The processor may also generate speed-time sequences and acceleration-time sequences by performing first-order or second-order differentiation on the position-time sequences.

[0170]In some embodiments, the processor may collect pressure sensor data connected to the two chambers of the hydraulic cylinders of the movable arm, the stick, and the bucket to form a plurality of sets of pressure-time sequences as the pressure sensing sequence.

[0171]In 720, the current operating mode of the current excavator may be determined based on the motion trajectory and the pressure sensing sequence.

[0172]In some embodiments, the processor may determine the current operating mode of the current excavator based on the motion trajectory and the pressure sensing sequence through a plurality of manners (e.g., table lookup, statistics, etc.).

[0173]For example, the processor may utilize a pattern recognition model to determine the current operating mode of the current excavator.

[0174]The pattern recognition model refers to a model utilized to determine the current operating mode. The pattern recognition model is a machine learning model. For example, the pattern recognition model may be any one or a combination of a Recurrent Neural Network (RNN) model or other customized model structures.

[0175]In some embodiments, an input of the pattern recognition model includes the motion trajectory and the pressure sensing sequence, and an output of the pattern recognition model is the current operating mode of the current excavator.

[0176]In some embodiments, the pattern recognition model may be obtained by the processor through a model training based on at least one set of second training samples and corresponding second labels. The second training samples include sample motion trajectories and sample pressure sensing sequences, and the second labels include historical operating modes.

[0177]In some embodiments, the processor may construct the second training samples based on historical data and/or experimental data. Merely by way of example, based on sample excavators equipped with high-precision sensors in various typical scenarios (e.g., earthwork, mining, municipal roads, etc.), sample motion trajectories and sample pressure sensing sequences of the movable arm, the stick, and the bucket are determined by collecting sensing data over a long time and on a large scale.

[0178]In some embodiments, the processor may determine the second labels corresponding to the second training samples through data annotation. Merely by way of example, while collecting sensing data, video is simultaneously recorded, and each second of video footage is manually annotated to determine a corresponding historical operating mode.

[0179]The training process of the pattern recognition model is similar to that of the parameter prediction model. For more content regarding training of the pattern recognition model, please refer to the parameter prediction model in FIG. 6.

[0180]In 730, a proportional coefficient, an integral coefficient, and a differential coefficient corresponding to the pressure feedback control signal may be determined based on the current operating mode.

[0181]For more descriptions regarding the pressure feedback control signal, the proportional coefficient, the integral coefficient, and the differential coefficient, please refer to the descriptions above regarding FIG. 1 to FIG. 5 and the related descriptions.

[0182]In some embodiments, the processor may determine the proportional coefficient, the integral coefficient, and the differential coefficient corresponding to the pressure feedback control signal based on the current operating mode through a plurality of manners (e.g., calculation, table lookup, etc.).

[0183]In some embodiments, the processor may determine the proportional coefficient, the integral coefficient, and the differential coefficient corresponding to the pressure feedback control signal by retrieving a parameter policy library. The parameter policy library may be a pre-built vector database.

[0184]In some embodiments, the parameter policy library includes a large count of key-value pairs. Data corresponding to a key includes the operating mode, and data corresponding to a value includes optimal coefficients corresponding to the key, which are determined by experts or obtained through offline optimization. Merely by way of example, a form of the value may be {k_p, k_i, k_d}, where k_p denotes the proportional coefficient corresponding to the pressure feedback control signal, k_i denotes the integral coefficient corresponding to the pressure feedback control signal, and k_d denotes the differential coefficient corresponding to the pressure feedback control signal. The parameter policy library includes optimal coefficients (e.g., optimal k_p, k_i, and k_d) matching different operating modes of the excavator.

[0185]In some embodiments, in response to identifying a change in the operating mode, the processor may automatically call and update the proportional coefficient, the integral coefficient, and the differential coefficient corresponding to the pressure feedback control signal from the parameter policy library.

[0186]In some embodiments, the parameter policy library may be constructed based on historical data or experimental data.

[0187]Merely by way of example, when the current operating mode is a digging cycle mode, the processor may set a control target to be rapid response and strong power. Based on experimental data, the processor may set an optimal k_p corresponding to the digging cycle mode to a large value to improve a response speed of the system, enabling a main pump pressure to quickly follow load changes. Based on experimental data, the processor may further set an optimal k_i corresponding to the digging cycle mode to a small value to avoid large overshoot caused by integral saturation, and set an optimal k_d corresponding to the digging cycle mode to a medium value to suppress oscillations caused by high proportional gain.

[0188]Merely by way of example, when the current operating mode is a leveling operating mode, the processor may set the control target to be extreme smoothness and no impact. Based on experimental data, the processor may set an optimal k_p corresponding to the leveling operating mode to a small value to reduce a response sensitivity of the system, making pressure changes more gradual. The processor may further set an optimal k_i corresponding to the leveling operating mode to a medium value to ensure precise elimination of steady-state errors and ensure pressure stability during gentle operation, and set an optimal k_d corresponding to the leveling operating mode to a large value to further enhance damping of the system and provide a smooth operation feel.

[0189]Merely by way of example, when the current operating mode is a crushing hammer mode, the processor may set the control target to be high flow stable output to suppress high-frequency pressure pulsations. Based on experimental data, the processor may set an optimal k_p corresponding to the crushing hammer mode to a medium value to ensure a moderate system response speed and sensitivity, set an optimal k_i corresponding to the crushing hammer mode to a large value to quickly eliminate pressure drops caused by crushing impacts, and set an optimal k_d corresponding to the crushing hammer mode to a small value to avoid excessive sensitivity of a differential term to high-frequency crushing impact signals, which may cause controller oscillations.

[0190]In some embodiments, by dynamically setting the proportional coefficient, the integral coefficient, and the differential coefficient corresponding to the pressure feedback control signal in different operating modes, a technical problem that the excavator has different requirements for system dynamic performance in different operating tasks may be solved, and a limitation that a traditional fixed-parameter controller cannot cover all operating conditions may be overcome.

[0191]In some embodiments, compared with a traditional load sensing system, the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system utilizes a pump-controlled driving mechanism and achieves precise control of an actuator motion by adjusting a rotational speed of a pump. When the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system is operating, each control valve is in a fully open state or a fully closed state, which can effectively eliminate the throttling loss, and achieve higher energy saving benefits.

[0192]In some embodiments, compared with a traditional distributed independent electro-hydraulic control system driven by a single pump and a single actuator, the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system introduces a main and auxiliary pump driving mechanism to achieve secondary pressure regulation, effectively expanding a system operating condition range.

[0193]In some embodiments, compared with a traditional distributed independent electro-hydraulic control system driven by a single pump and a single actuator, when the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system is applied to a hydraulic excavator, a one-way constant pressure pump is arranged in a cabin, and each bidirectional pump unit is arranged on an arm frame to control the motion of the movable arm, the stick, and the bucket, respectively. Such an operating mode can effectively reduce a peak output power of each bidirectional hydraulic pump unit on the arm frame, further reduce an overall size of each hydraulic pump unit, effectively save manufacturing costs of key components, and optimize the compactness of the arm frame.

[0194]One or more embodiments of the present disclosure provide the distributed independent secondary pressure regulating open-circuit pump-controlled hydraulic system, including: the secondary pressure regulating transmission control system and the hydraulic power-supply system. The system further includes a first hydraulic control system (43), a second hydraulic control system (44), and a third hydraulic control system (45). Each of the first hydraulic control system (43), the second hydraulic control system (44), and the third hydraulic control system (45) includes the integrated electro-hydraulic actuator. The integrated electro-hydraulic actuators of the first hydraulic control system (43), the second hydraulic control system (44), and the third hydraulic control system (45) are independently mounted on a corresponding hydraulic cylinder in sequence. The three systems control the movable arm, the stick, and the bucket respectively. The second hydraulic control system (44) utilizes the three-position four-way electromagnetic switching valve to achieve four-quadrant operation switching of the stick.

[0195]For a person skilled in the art, it is apparent that the present disclosure is not limited to the details of the exemplary embodiments described above. The present disclosure may be implemented in other specific forms without departing from the spirit or essential characteristics of the present disclosure. Therefore, the embodiments should be regarded as exemplary and non-limiting from any perspective. The scope of the present disclosure is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all changes falling within the meaning and scope of equivalent elements of the claims be embraced within the present disclosure. Any reference signs in the claims should not be construed as limiting the related claims.

[0196]In the description of the present disclosure, unless otherwise specified, “a plurality of” means two or more. Terms such as “upper,” “lower,” “left,” “right,” “inner,” “outer,” “front end,” “rear end,” “head,” and “tail” indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are used only for ease of description of the present disclosure and simplification of the description, and do not indicate or imply that the mentioned apparatus or element must have a specific orientation or be constructed and operated in a specific orientation. Therefore, these terms should not be construed as limiting the present disclosure. In addition, terms such as “first,” “second,” and “third” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In the description of the present disclosure, it should be noted that unless otherwise explicitly specified and defined, the terms “connected” and “connection” should be understood broadly. For example, the connection may be a fixed connection or a detachable connection. The connection may be a mechanical connection or an electrical connection. The connection may be a direct connection or an indirect connection through an intermediate medium. For a person of ordinary skill in the art may understand the specific meanings of the foregoing terms in the present disclosure based on specific situations.