LAUNDRY WASHING MACHINE LEVEL CALIBRATION

BACKGROUND

[0001]Laundry washing machines are used in many single-family and multi-family residential applications to clean clothes and other fabric items. Due to the wide variety of items that may need to be cleaned by a laundry washing machine, many laundry washing machines provide a wide variety of user-configurable settings to control various aspects of a wash cycle such as water temperatures and/or amounts, agitation, soaking, rinsing, spinning, etc. The settings cycle can have an appreciable effect on washing performance, as well as on energy and/or water consumption, so it is generally desirable for the settings used by a laundry washing machine to appropriately match the needs of each load washed by the machine.

[0002]One particular area in which laundry washing machine performance may be sub-optimal is spinning a wash basket. It has been found that different spin speeds and/or durations are better suited for different types of loads, e.g., bedding, towels, cottons, delicates, athletic apparel, etc. Spinning at higher speeds generally removes more wash fluid, and does so more quickly, although doing so consumes more energy and generates greater noise, and can cause increased wear on clothing. In addition, bulky loads can often become unbalanced, such that higher speed spins may result in loud banging and vibrations, which can further lead to premature wear on a laundry washing machine. Lower speed spins, in contrast, are generally quieter and gentler on clothing, but are less effective, and may be insufficient for bulky and highly absorbent materials.

[0003]Further, while various control methodologies may be developed to optimize laundry washing machine performance, a significant challenge associated with such methodologies is the varied environments within which laundry washing machines may be installed, as a control methodology and/or the operational settings used thereby that are optimized for particular environmental conditions may not be optimal for installations that depart significantly from those environmental conditions. For example, installation of a laundry washing machine on a surface that is not level can cause excessive vibrations, particularly when spinning the load, and even when vibration-reducing structures such as suspension assemblies are used in the laundry washing machine. A wash basket that is not close to level can lead to excessive vibrations that can require a decreased spin speed, even when the load is not unbalanced. Where a load is unbalanced, these problems are exacerbated and can lead to even greater vibrations, increased noise, as well as wear on bearings and other kinetic components. These problems may also lead to increased out-of-balance events, which can increase the length of wash/spin operations, and in some instances, require a wash cycle to ultimately be restarted.

[0004]Therefore, a significant need also exists in the art for a manner of adapting the control methodologies and/or operational settings that may be used to optimize laundry washing machine performance for use in different installations.

SUMMARY

[0005]The invention addresses these and other problems associated with the art by providing a laundry washing machine and method that utilize a plurality of level sensors capable of outputting signals from which the orientation of a wash tub relative to level can be determined. The signals may then be used to determine a level state of the wash tub, which may then be used to level the laundry washing machine and thereby optimize the performance thereof.

[0006]Therefore, consistent with one aspect of the invention, a laundry washing machine may include a wash tub suspended within a housing by a suspension assembly and configured to receive a load of laundry, a plurality of level sensors disposed at respective rotational positions about the wash tub and configured to output respective signals that vary at least in part based on the orientation of the wash tub relative to level, and a controller coupled to the plurality of level sensors and configured to perform a wash cycle to wash the load of laundry in the wash tub, the controller further configured to determine a level state of the wash tub using the respective signals output by the plurality of level sensors.

[0007]In some embodiments, the suspension assembly is configured to allow for relative movement between the wash tub and the housing. Also, in some embodiments, the plurality of level sensors includes a plurality of force sensors configured to sense a weight of the wash tub. Further, in some embodiments, each force sensor is a load cell operably coupled between the wash tub and the housing. In some embodiments, the suspension assembly including a plurality of suspension rods, and each force sensor is operably coupled to a suspension rod of the plurality of suspension rods. In addition, in some embodiments, the controller is further configured to determine a weight of the load of laundry or sense an out of balance load during the wash cycle using the respective signals of one or more of the plurality of level sensors.

[0008]In some embodiments, the plurality of level sensors includes a plurality of capacitive sensors disposed at respective rotational positions about the wash tub to detect fluid in the wash tub, the plurality of capacitive sensors configured to output respective signals that vary at least in part based on the orientation of the wash tub relative to level when fluid is in the wash tub. In addition, in some embodiments, at least a portion of at least one of the plurality of capacitive sensors is embedded in a wall of the wash tub or mounted on an outer wall surface of the wash tub. Moreover, in some embodiments, the controller is further configured to sense a water level in the wash tub during the wash cycle using the respective signals of one or more of the plurality of capacitive sensors. In some embodiments, the controller is further configured to sense a moisture level in the load during the wash cycle or determine a fabric type of the load using the respective signals of one or more of the plurality of capacitive sensors. Moreover, in some embodiments, the controller is configured to dispense a predetermined volume of water into the wash tub such that determining the level state of the wash tub is performed while the predetermined volume of water is in the wash tub.

[0009]In some embodiments, the plurality of level sensors include four level sensors spaced about a vertical axis extending through the wash tub, and the controller is configured to determine the level state of the wash tub by calculating respective first and second differences between the respective signals of first and second opposing pairs of level sensors from the plurality of level sensors. In addition, in some embodiments, the controller is further configured to determine the level state of the wash tub by applying first and second tare values to the first and second differences. In some embodiments, the first and second tare values are determined during a calibration operation performed during manufacture of the laundry washing machine, the calibration operation configured to determine the first and second tare values by calculating respective first and second differences between the respective signals of the first and second opposing pairs of level sensors from the plurality of level sensors.

[0010]Moreover, in some embodiments, the controller is further configured to, during a leveling operation, generate a level display on a user interface to guide a user as the user manually adjusts at least one height adjusters of the laundry washing machine. Also, in some embodiments, the four level sensors are oriented proximate four corners of the laundry washing machine, the controller is further configured to mathematically rotate the first and second differences 45 degrees and to generate the level display using the mathematically rotated first and second differences.

[0011]Some embodiments may also include at least one electromechanical height adjuster, and the controller is configured to actuate the at least one electromechanical height adjuster during a leveling operation in response to the determined level state. In addition, in some embodiments, the controller is configured to inhibit initiation of a wash cycle or dynamically determine a spin operation to be performed during the wash cycle based on the determined level state.

[0012]Consistent with another aspect of the invention, a laundry washing machine may include a wash tub supported within a housing and configured to receive a load of laundry, a plurality of force sensors disposed at respective positions in the housing and configured to output respective signals that vary at least in part based on the orientation of at least a portion of the laundry washing machine relative to level, and a controller coupled to the plurality of weight sensors and configured to perform a wash cycle to wash the load of laundry in the wash tub, the controller further configured to determine a level state of the laundry washing machine using the respective signals output by the plurality of weight sensors.

[0013]Consistent with another aspect of the invention, a laundry washing machine may include a wash tub supported within a housing and configured to receive a load of laundry, a plurality of capacitive sensors disposed at respective rotational positions about the wash tub to detect fluid in the wash tub, the plurality of capacitive sensors configured to output respective signals that vary at least in part based on the orientation of the wash tub relative to level when fluid is in the wash tub, and a controller coupled to the plurality of capacitive sensors and configured to perform a wash cycle to wash the load of laundry in the wash tub, the controller further configured to determine a level state of the laundry washing machine using the respective signals output by the plurality of weight sensors.

[0014]Other embodiments may include various methods of operating a laundry washing machine utilizing the various operations described above.

[0015]These and other advantages and features, which characterize the invention, are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which there is described example embodiments of the invention. This summary is merely provided to introduce a selection of concepts that are further described below in the detailed description, and is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view of a top-load laundry washing machine consistent with some embodiments of the invention.

[0017]FIG. 2 is a perspective view of a front-load laundry washing machine consistent with some embodiments of the invention.

[0018]FIG. 3 is a functional vertical section of the laundry washing machine of FIG. 1.

[0019]FIG. 4 is a block diagram of an example control system for the laundry washing machine of FIG. 1.

[0020]FIG. 5 is a top plan view of the laundry washing machine of FIG. 1, with a top cover removed.

[0021]FIG. 6 is a flowchart illustrating an example operational sequence for calibrating the laundry washing machine of FIG. 1.

[0022]FIG. 7 is a flowchart illustrating an example operational sequence for leveling the laundry washing machine of FIG. 1.

[0023]FIG. 8 is an example display presented to a user during the operational sequence of FIG. 7.

[0024]FIG. 9 is a flowchart illustrating an operational sequence for implementing a wash cycle in the laundry washing machine of FIG. 1.

[0025]FIG. 10 is a perspective view of a wash tub suitable for use in a laundry washing machine consistent with some embodiments of the invention.

[0026]FIG. 11 is a flowchart illustrating an operational sequence for implementing a wash cycle in a laundry washing machine utilizing the wash tub referenced in FIG. 10.

[0027]FIGS. 12-15 are perspective views of additional wash tubs suitable for use in a laundry washing machine consistent with some embodiments of the invention.

[0028]FIG. 16 is a cross-sectional view of a wash tub suitable for use in a laundry washing machine consistent with some embodiments of the invention.

DETAILED DESCRIPTION

[0029]Embodiments consistent with the invention may be used in connection with leveling a laundry washing machine. In particular, in some embodiments consistent with the invention, a plurality of level sensors may be used to determine a level state of a wash tub of a laundry washing machine, thereby enabling the laundry washing machine to be leveled at an installation location to optimize the performance thereof.

[0030]Turning now to the drawings, wherein like numbers denote like parts throughout the several views, FIG. 1 illustrates an example laundry washing machine 10 in which the various technologies and techniques described herein may be implemented. Laundry washing machine 10 is a top-load washing machine, and as such includes a top-mounted door 12 in a cabinet or housing 14 that provides access to a vertically-oriented wash tub 16 housed within the cabinet or housing 14. Door 12 is generally hinged along a side or rear edge and is pivotable between the closed position illustrated in FIG. 1 and an opened position (not shown). When door 12 is in the opened position, clothes and other washable items may be inserted into and removed from wash tub 16 through an opening in the top of cabinet or housing 14. Control over washing machine 10 by a user is generally managed through a control panel 18 disposed on a backsplash and implementing a user interface for the washing machine, and it will be appreciated that in different washing machine designs, control panel 18 may include various types of input and/or output devices, including various knobs, buttons, lights, switches, textual and/or graphical displays, touch screens, etc. through which a user may configure one or more settings and start and stop a wash cycle.

[0031]The embodiments discussed hereinafter will focus on the implementation of the hereinafter-described techniques within a top-load residential laundry washing machine such as laundry washing machine 10, such as the type that may be used in single-family or multi-family dwellings, or in other similar applications. However, it will be appreciated that the herein-described techniques may also be used in connection with other types of laundry washing machines in some embodiments. For example, the herein-described techniques may be used in commercial applications in some embodiments. Moreover, the herein-described techniques may be used in connection with other laundry washing machine configurations. FIG. 2, for example, illustrates a front-load laundry washing machine 20 that includes a front-mounted door 22 in a cabinet or housing 24 that provides access to a horizontally-oriented wash tub 26 housed within the cabinet or housing 24, and that has a control panel 28 positioned towards the front of the machine rather than the rear of the machine as is typically the case with a top-load laundry washing machine. Implementation of the herein-described techniques within a front-load laundry washing machine would be well within the abilities of one of ordinary skill in the art having the benefit of the instant disclosure, so the invention is not limited to the top-load implementation discussed further herein.

[0032]FIG. 3 functionally illustrates a number of components in laundry washing machine 10 as is typical of many washing machine designs. For example, wash tub 16 may be vertically oriented, generally cylindrical in shape, opened to the top and capable of retaining water and/or wash liquor dispensed into the washing machine. Wash tub 16 may be supported by a suspension system such as a set of suspension rods 30 with corresponding vibration dampening springs 32.

[0033]Disposed within wash tub 16 is a wash basket 34 that is rotatable about a generally vertical axis A by a drive system 36. Wash basket 34 is generally perforated or otherwise provides fluid communication between an interior 38 of the wash basket 34 and a space 40 between wash basket 34 and wash tub 16. Drive system 36 may include, for example, an electric motor and a transmission and/or clutch for selectively rotating the wash basket 34. In some embodiments, drive system 36 may be a direct drive system, whereas in other embodiments, a belt or chain drive system may be used.

[0034]In addition, in some embodiments an agitator 42 such as an impeller, auger or other agitation element may be disposed in the interior 38 of wash basket 34 to agitate items within wash basket 34 during a washing operation. Agitator 42 may be driven by drive system 36, e.g., for rotation about the same axis as wash basket 34, and a transmission and/or clutch within drive system 36 may be used to selectively rotate agitator 42. In other embodiments, separate drive systems may be used to rotate wash basket 34 and agitator 42.

[0035]A water inlet 44 may be provided to dispense water into wash tub 16. In some embodiments, for example, hot and cold valves 46, 48 may be coupled to external hot and cold water supplies through hot and cold inlets 50, 52, and may output to one or more nozzles 54 to dispense water of varying temperatures into wash tub 16. In addition, a pump system 56, e.g., including a pump and an electric motor, may be coupled between a low point, bottom, or sump in wash tub 16 and an outlet 58 to discharge greywater from wash tub 16. In some embodiments, it may be desirable to utilize multiple nozzles 54, and in some instances, oscillating nozzles 54, such that water dispensed into the wash tub is evenly distributed over the top surface of the load.

[0036]In some embodiments, laundry washing machine 10 may also include a dispensing system 60 configured to dispense detergent, fabric softener and/or other wash-related products into wash tub 16. Dispensing system 60 may be configured in some embodiments to dispense controlled amounts of wash-related products, e.g., as may be stored in a reservoir (not shown) in laundry washing machine 10. In other embodiments, dispensing system 60 may be used to time the dispensing of wash-related products that have been manually placed in one or more reservoirs in the machine immediately prior to initiating a wash cycle. Dispensing system 60 may also, in some embodiments, receive and mix water with wash-related products to form one or more wash liquors that are dispensed into wash tub 16. In still other embodiments, no dispensing system may be provided, and a user may simply add wash-related products directly to the wash tub prior to initiating a wash cycle.

[0037]It will be appreciated that the particular components and configuration illustrated in FIG. 3 is typical of a number of common laundry washing machine designs. Nonetheless, a wide variety of other components and configurations are used in other laundry washing machine designs, and it will be appreciated that the herein-described functionality generally may be implemented in connection with these other designs, so the invention is not limited to the particular components and configuration illustrated in FIG. 3.

[0038]Further, to support various automated functionality described herein, laundry washing machine 10 also may also include one or more sensors. A plurality of level sensors 62, for example, may be used to level a laundry washing machine, in some embodiments based on the orientation of the wash tub 16, rather than the orientation of the laundry washing machine itself. One or more of the level sensors 62 may also be used in some embodiments as force sensors to sense the mass or weight of the contents of the wash tub. In the illustrated embodiment, for example, each level sensor 62 may be implemented as a load cell coupled to one of the suspension rods 30, or alternatively on other structures supporting the wash tub, e.g., a leg, spring, or damper. Each load cell may be an electro-mechanical sensor that outputs a signal that varies with a displacement based on load or weight, and thus outputs a signal that varies with the weight of the contents of wash tub 16, and based on a comparison of the signals output by multiple load cells or other sensors a level state of the laundry washing machine may be determined. In other embodiments, other types of transducers or sensors that generate a signal that varies with applied force, e.g., strain gauges, may be used. Furthermore, in other embodiments, load cells, or other appropriate transducers or sensors, may be positioned elsewhere in a laundry washing machine to generate a plurality of signals that vary in response to the weight of the contents of wash tub 16. In some embodiments, for example, transducers may be used to support an entire load washing machine, e.g., a plurality of legs of a machine. Other types and/or locations of transducers suitable for generating a signal that varies with the weight of the contents of a wash tub will be apparent to one of ordinary skill in the art having the benefit of the instant disclosure. In addition, in some embodiments, a force or level sensor may also be used for vibration sensing purposes, e.g., to detect excessive vibrations resulting from an out-of-balance load. In other embodiments, however, no vibration sensing may be used, while in other embodiments, separate sensors may be used to sense vibrations.

[0039]A fluid level sensor may be used to generate a signal that varies with the level or height of fluid in wash tub 16. In the illustrated embodiment, for example, a fluid level sensor may be implemented using a pressure sensor 64 in fluid communication with a low point, bottom or sump of wash tub 16 through a tube 66 such that a pressure sensed by pressure sensor 64 varies with the level of fluid within the wash tub. It will be understood that the addition of fluid to the wash tub will generate a hydrostatic pressure within the tube that varies with the level of fluid in the wash tub, and that may be sensed, for example, with a piezoelectric or other transducer disposed on a diaphragm or other movable element. It will be appreciated that a wide variety of pressure sensors may be used to provide fluid level sensing, including, among others, combinations of pressure switches that trigger at different pressures. It will also be appreciated that fluid level in the wash tub may also be sensed using various non-pressure based sensors, e.g., optical sensors, laser sensors, etc.

[0040]Additional sensors may also be incorporated into laundry washing machine 10, e.g., turbidity, conductivity, and/or flow sensors. In addition, in some embodiments, a camera or other image sensor 68 may be used, for example, to sense the colors of items in a load to be washed by laundry washing machine 10, or to sense other aspects of a load placed in the wash tub. In some in instances, image sensor 68 may be located proximate an opening of the wash tub 16, facing down into the wash tub. In other embodiments, however, image sensor 68 may be oriented generally upwardly facing and/or may be positioned elsewhere in the laundry washing machine, e.g., on a door, proximate a top edge of a door on a front-load laundry washing machine, and in other suitable locations.

[0041]In addition, in some embodiments, one or more legs 70 of laundry washing machine 10 may include height adjusters 72 to assist in leveling the laundry washing machine. Height adjusters 72 may be manually activated in some embodiments, e.g., by spinning the legs to turn respective threaded shafts that vary how far the legs project below the laundry washing machine, while in other embodiments height adjusters 72 may be electromechanical in nature, and controllable by a controller of the laundry washing machine to automatically raise and lower the legs.

[0042]Now turning to FIG. 4, laundry washing machine 10 may be under the control of a controller 80 that receives inputs from a number of components and drives a number of components in response thereto. Controller 80 may, for example, include one or more processors 82 and a memory 84 within which may be stored program code for execution by the one or more processors. The memory may be embedded in controller 80, but may also be considered to include volatile and/or non-volatile memories, cache memories, flash memories, programmable read-only memories, read-only memories, etc., as well as memory storage physically located elsewhere from controller 80, e.g., in a mass storage device or on a remote computer interfaced with controller 80.

[0043]As shown in FIG. 4, controller 80 may be interfaced with various components, including the aforementioned drive system 36, hot/cold inlet valves 46, 48, pump system 56, dispenser 60, level sensors 62, fluid level sensor 64, image sensor 68, and height adjusters 72 (if electromechanically implemented). In addition, controller 80 may be interfaced with additional components such as a door switch that detects whether door 12 is in an open or closed position and a door lock that selectively locks door 12 in a closed position. Moreover, controller 80 may be coupled to a user interface 86 including various input/output devices such as knobs, dials, sliders, switches, buttons, lights, textual and/or graphics displays, touch screen displays, speakers, image capture devices, microphones, etc. for receiving input from and communicating with a user. In some embodiments, controller 80 may also be coupled to one or more network interfaces 88, e.g., for interfacing with one or more external devices via wired and/or wireless networks such as Ethernet, Bluetooth, NFC, cellular and other suitable networks. Additional components may also be interfaced with controller 80, as will be appreciated by those of ordinary skill having the benefit of the instant disclosure. Moreover, in some embodiments, at least a portion of controller 80 may be implemented externally from a laundry washing machine, e.g., within a mobile device, a cloud computing environment, etc., such that at least a portion of the functionality described herein is implemented within the portion of the controller that is externally implemented.

[0044]In some embodiments, controller 80 may operate under the control of an operating system and may execute or otherwise rely upon various computer software applications, components, programs, objects, modules, data structures, etc. In addition, controller 80 may also incorporate hardware logic to implement some or all of the functionality disclosed herein. Further, in some embodiments, the sequences of operations performed by controller 80 to implement the embodiments disclosed herein may be implemented using program code including one or more instructions that are resident at various times in various memory and storage devices, and that, when read and executed by one or more hardware-based processors, perform the operations embodying desired functionality. Moreover, in some embodiments, such program code may be distributed as a program product in a variety of forms, and that the invention applies equally regardless of the particular type of computer readable media used to actually carry out the distribution, including, for example, non-transitory computer readable storage media. In addition, it will be appreciated that the various operations described herein may be combined, split, reordered, reversed, varied, omitted, parallelized and/or supplemented with other techniques known in the art, and therefore, the invention is not limited to the particular sequences of operations described herein.

Wash Tub Level Sensing

[0045]As noted above, the level state of a laundry washing machine can significantly impact the performance of the machine, as an unlevel machine can increase vibrations, noise, and wear on bearings and other kinetic components when a wash basket is spun during wash, rinse, and/or spin operations. Excessive vibrations can also lead to out-of-balance events, which can lengthen wash/spin cycles, or cause those cycles to be interrupted.

[0046]Traditionally, laundry washing machines have been provided with height adjustable legs, and users are encouraged to adjust the legs such that all legs firmly touch the ground, and such that the housing of the laundry washing machine is level. The level state of the machine is typically determined using a separate bubble level that is placed on the housing, and the legs are adjusted until the housing of the laundry washing machine is close to level in both forward-to-back and side-to-side directions.

[0047]However, leveling a laundry washing machine in such a manner has a number of drawbacks. First, just because the housing of a machine is level does not necessarily mean that the wash tub of the machine is also level. As noted above, a wash tub may be supported in a housing through the use of a suspension assembly, e.g., a set of suspension rods, that allow the wash tub to move relative to the housing to dampen vibrations that are generated when a wash basket within the wash tub is spun. Generally, when the wash tub of the laundry washing machine is level, the springs in the suspension rods will be evenly preloaded, and will be more effective at damping vibrations when the wash basket is spinning. In addition, the axis of rotation of the wash basket will generally be more parallel to the force of gravity, thereby minimizing the effects of gyroscopic precession on the wash basket, and further lessening the amplitude of vibrations when the basket is spinning.

[0048]However, due to various manufacturing tolerances, wear in the suspension assembly, etc., a wash tub may not be suspended perfectly level relative to the force of gravity when the housing of the laundry washing machine itself is level. As such, leveling a washing machine using a separate bubble level set on the housing does not always result in the wash tub itself being level.

[0049]Second, the level state of a laundry washing machine may change over time, not only due to wear in the suspension assembly, but also due to changes in the location of the laundry washing machine on the floor (e.g., as a result of vibrations over time and/or physically adjusting the location of the laundry washing machine), and even changes in the level state of the floor itself over time. Thus, even if a machine is leveled at initial installation, the level state of the machine may change over time.

[0050]Third, some users may simply install a laundry washing machine without leveling the machine as suggested by the manufacturer.

[0051]In embodiments consistent with the invention, however, a plurality of level sensors may be integrated into the laundry washing machine itself and may be used to determine the level state of the laundry washing machine. By doing so, the level state of the machine may be determined at various points after installation (e.g., prior to each wash cycle, on demand in response to user input, etc.), and may be used to alert the user to a potential out-of-level condition, and in some instances, allow a controller to adjust the wash cycle (e.g., to reduce the spin speed) and/or inhibit performance of a wash cycle in response to an out-of-level condition. In addition, in some embodiments, the level state is specifically of the wash tub itself, rather than that of the overall laundry washing machine (as might be determined based on the level state of a surface of the laundry washing machine housing), such that any discrepancies between the wash tub and the laundry washing machine housing (e.g., due to the suspension assembly) may be resolved in favor of leveling the wash tub, i.e., the component that supports the wash basket and many of the other potentially vibration-generating components in the laundry washing machine.

[0052]By utilizing a plurality of level sensors integrated into a laundry washing machine, a machine may be calibrated in an end-of-line process during manufacturing, and one or more calibration values, referred to herein as tare values, may be determined and stored in a non-volatile memory in the laundry washing machine. The tare values may then be used to calculate a level state of the laundry washing machine during installation, as well as at different times over the life of the machine. In some embodiments, for example, a level state may include a degree and/or angle of level. The degree of level, for example, may represent an amount that the wash tub departs from level, while the angle may represent a direction around the vertical axis that the machine slopes relative to the horizontal plane that is perpendicular to the vertical axis. In some embodiments, for example, the degree of level may be represented using an angle between the vertical axis relative to gravity and the vertical axis of the wash tub and about which the wash basket spins, or alternatively, a distance between the two axes at a predetermined distance from the intersection of those axes (e.g., proximate the location of one or more legs of the machine). The angle of level may also be represented by an angle in some embodiments, e.g., relative to a home position about the vertical axis of the machine, such as the front-to-back direction of the machine. In some embodiments, a level state may also include information regarding the adjustments needed for leveling the wash tub or machine, e.g., one or more corners of the laundry washing machine and the distance the leveling leg(s) at the corner(s) should be adjusted. In other embodiments, the degree of level may be represented using an (X, Y) location in a cartesian plane relative to an origin representing a level state. Other manners of representing the level state may be used in other embodiments, however, so the invention is not limited to these specific representations.

[0053]Now turning to FIG. 5, and with continuing reference to FIGS. 1-4, in some embodiments the level sensors may be implemented using force sensors such as load cells 62, which are mounted in line with suspension rods 30 and dampening springs 32 supporting tub 16 of a washing machine from housing 14. In some embodiments, for example, housing 14 may include a set of supports 90 from which suspension rods 30 hang, and load cells 62 may be interposed between supports 90 and suspension rods 30 to sense the magnitude of force each suspension rod is experiencing from wash tub 16, including due to the gravity and inertia of the wash tub itself and anything housed within the wash tub. Because the wash tub is suspended by only these four rods, the tub can pivot inside the housing, and if the laundry washing machine is not perfectly level, the wash tub will hang at an angle, which will change the distribution of weight on the suspension rods. The difference between the readings of the load cells may therefore be used to determine how level the laundry washing machine is, as the more evenly this weight is distributed on the suspension rods, the more level the wash tub, and thus the laundry washing machine, is.

[0054]It will be appreciated that in some embodiments, there may be some error caused by the suspension springs, as the suspension springs are designed to keep the wash tub suspended equally. If there is no load on the springs, the angle of the wash tub may be corrected by the suspension springs. In addition, in some embodiments, there may also be some static friction between the springs and the wash tub that must be overcome before the wash tub changes its orientation in the housing. It may be desirable in some embodiments to reduce this friction with different mounting geometries and/or different spring grease. In addition, to accommodate for these possible errors, the laundry washing machine may also be filled with some amount of water when being calibrated in the factory, and then refilled prior to determining the level state of the laundry washing machine during installation or thereafter to the same volume of water or an arbitrary volume. Doing so may inhibit the springs from affecting the measurement of the load cells. In other embodiments, however, level sensing may be performed when the wash tub is empty.

[0055]As may be seen in FIG. 5, the four load cells 62 are spaced about the vertical axis A that extends through the center of wash tub 16, and are disposed proximate the four corners of the housing 14. It will be appreciated, however, that other locations and/or numbers of load cells may be used in other embodiments, e.g., two or three load cells and/or load cells oriented towards the sides, front and back of the laundry washing machine, among other variations. In some embodiments, for example, a wash tub could be suspended from three suspension rods rotationally offset by 120 degrees relative to one another, with three load cells used to sense the level state of the laundry washing machine.

[0056]As noted above, it may be desirable to calibrate a laundry washing machine during manufacture to generate calibration or tare values that may be used in future leveling operations. FIG. 6, for example, illustrates an operational sequence 100 for calibrating a laundry washing machine during an end-of-line process during manufacturing. In block 102, a predetermined amount of water may be dispensed in the wash tub to reduce suspension system effects during the calibration process. Alternatively, block 102 may be skipped, and calibration may be performed using an empty wash tub. In either event, the laundry washing machine is supported on a known level surface, and optionally with the leveling legs set at equal heights.

[0057]Next, in block 104, load cell values are captured for the four load cells, and in block 106, X and Y tare values are calculated from these readings. The tare values are then stored in a non-volatile memory of the laundry washing machine (e.g., an EEPROM) in block 108, and calibration is complete.

[0058]For example, where the four load cells are disposed in the corners as illustrated in FIG. 5, the tare values may be calculated as the differences between the values sensed by the load cells in the opposite corners of the laundry washing machine. Thus, for example, if one pair of load cells are designated X_0 and X_1, and the other are designated Y_0 and Y_1, X_Tare and Y_Tare values may be calculated as:

$\begin{array}{cc}\mathrm{X\_Tare}=\mathrm{X\_}0-\mathrm{X\_}1& \left(1\right)\end{array}$$\begin{array}{cc}\mathrm{Y\_Tare}=\mathrm{Y\_}0-\mathrm{Y\_}1& \left(2\right)\end{array}$

[0059]During laundry washing machine startup, the X_Tare and Y_Tare values maybe retrieved from non-volatile storage and used in level sensing operations to generate an (X, Y) location representative of the level state of the laundry washing machine, as follows:

$\begin{array}{cc}X=\mathrm{X\_}0-\mathrm{X\_}1-\mathrm{X\_Tare}& \left(3\right)\end{array}$$\begin{array}{cc}Y=\mathrm{Y\_}0-\mathrm{Y\_}1-\mathrm{Y\_Tare}& \left(4\right)\end{array}$

[0060]The (X, Y) location, for example, may represent a cartesian distance from an (0, 0) origin representing a leveled condition for the laundry washing machine, such that the closer the cartesian coordinates of the level state are to the origin, the closer the laundry washing machine is to a leveled condition.

[0061]In some embodiments, it may also be desirable to display the origin and the coordinates representing the current level state of the laundry washing machine to facilitate leveling by a user. Where the load cells are oriented in the corners of the housing as illustrated in FIG. 5, it may therefore also be desirable to mathematically rotate the coordinates for properly orienting the coordinate system with the display, e.g., using equations (5) and (6) below:

$\begin{array}{cc}\mathrm{adjustedX}=\left(X-Y\right)/\mathrm{SQRT}\left(2\right)& \left(5\right)\end{array}$$\begin{array}{cc}\mathrm{adjustedY}=\left(X+Y\right)/\mathrm{SQRT}\left(2\right)& \left(6\right)\end{array}$

[0062]FIG. 7 illustrates an example operational sequence 120 for performing a leveling operation during or after installation of a laundry washing machine. In block 122, a predetermined amount of water is optionally dispensed into the wash tub to reduce suspension system effects, in a similar manner to that described above in connection with FIG. 6. The same amount of water as used during calibration, or a different amount of water, may be dispensed in different embodiments, and in some embodiments, block 122 may be skipped, and leveling may be performed using an empty wash tub.

[0063]Next, in block 124, load cell values are captured for the four load cells, and a relative level state of the laundry washing machine is determined in block 126, e.g., by applying equations (3) and (4) above and using the tare values stored during calibration. The level state is then tested to determine if it meets a level criterion in block 128, e.g., if the level state is within a predetermined tolerance from a perfectly level state, and if it is, the leveling operation is complete.

[0064]If not, however, block 128 passes control to block 130, where the X and Y values calculated using equations (3) and (4) are rotated 45 degrees, and the results are displayed to the user in block 132. It will be appreciated that if no graphical display is used and/or other load cell locations are used, blocks 130 and 132 may be omitted.

[0065]Next, as represented by blocks 134 and 136, manual adjustments of one or more manual height adjusters by a user and/or automatic adjustments of one or more electromechanical height adjusters by the controller may be performed, and control returns to block 124 to capture new load cell values. As such, the level state of the laundry washing machine may be determined dynamically as a user and/or the controller adjusts the height adjusters until a sufficiently leveled condition is obtained.

[0066]While a number of different displays may be used in different embodiments, FIG. 8 illustrates one example display 140 that simulates a bullseye-type bubble level, where the current level state of the laundry washing machine is represented using a first icon 142 disposed at coordinates corresponding to the (X, Y) values calculated above, and with the origin (representing a perfectly leveled condition) represented using a second icon 144. A user may be presented with various guides, e.g., an arrow 146 and/or textual instructions 148 that indicate which height adjuster(s) should be adjusted and how much. As the height adjusters are adjusted, icon 142 will move towards icon 144, and a leveled condition will be represented when icon 142 overlaps with icon 144, as represented at position 142′.

[0067]Other manners of displaying the current level state of a laundry washing machine, its relationship to a leveled condition, and in some instances, the instructions for obtaining the leveled condition, may be used in different embodiments, including other textual and/or graphical displays, audible cues, vocal instructions, etc. In addition, the presentation of such information may be made on the laundry washing machine user interface and/or using an external device, e.g., a mobile device running a mobile app in communication with the laundry washing machine.

[0068]Next, turning to FIG. 9, once the laundry washing machine is leveled, the load cells may be used to periodically check the level state of the laundry washing machine, as well as perform other operations, as will be discussed in greater detail below. In particular, FIG. 9 illustrates an operational sequence 160 for performing a wash cycle using the laundry washing machine. At the start of the wash cycle, load cell values may be captured in block 162, and the values of one or more of the load cells may be used to determine a weight of the load contained in the wash tub (e.g., via a comparison with an empty weight of the wash tub, e.g., as may be captured during installation) in block 164. In addition, in block 166 a level state of the laundry washing machine may be determined using the load cell values, and block 168 may determine if a level error criterion has been met. The level error criterion may be configured to inhibit initiation of a wash cycle if it is determined that the level state is excessively unlevel, and as such, if the criterion is met, control may pass to block 170 to notify the user (e.g., via a display, a mobile app, a notification, etc.) of the need to level the laundry washing machine.

[0069]If the level error criterion is not met, however, control passes to block 172 to determine a spin profile for the wash cycle. For example, where the level state of the laundry washing machine is not so unlevel as to trigger the level error criterion but is still relatively unlevel to where higher speed spin operations could lead to knocking, excessive vibrations, or out-of-balance conditions, it may be desirable to reduce the maximum spin speed during the wash cycle. In contrast, if the level state is close to a perfectly leveled condition, higher speed spin operations may be justified due to a reduced risk of excessive vibrations.

[0070]Next, in block 174, additional wash cycle parameters are determined, e.g., load type, wash and/or rinse operation types, durations, repetitions, etc., using various operations that will be apparent to those of ordinary skill in the art having the benefit of the instant disclosure. At least some of these parameters may be determined at least in part using the load weight determined using the load cell values. Then, in block 176, the wash cycle is performed, using the various parameters and profiles determined above. In addition, the load cells may also be monitored during the wash cycle to detect an out of balance load, e.g., in response to detecting force variations above a predetermined threshold. Thus, it will be appreciated that the load cell values may be used for purposes beyond determining a level state of the laundry washing machine in some embodiments.

[0071]While the aforementioned embodiments have focused on the use of load cells for sensing a level state of a laundry washing machine, in other embodiments, other level sensor implementations may be used. For example, it may be desirable in some embodiments to utilize a plurality of capacitive sensors as level sensors. The capacitive sensors may be disposed at a plurality of rotational positions about a wash tub to detect a fluid level in the wash tub at the different rotational positions. It will be appreciated that fluid retained in a stationary wash tub will inherently be level, so by comparing water levels sensed at multiple rotational positions about a wash tub, the relative level state of the wash tub, and thus the laundry washing machine, may be determined. In particular, as the orientation of the wash tub varies relative to level when fluid is in the wash tub, the differences in the fluid levels sensed by the capacitive sensors at different rotational positions will also vary.

[0072]It will be appreciated that capacitive level sensors may be implemented in a number of different manners, e.g., using a pair of insulated wires or conductive strips along with one or more resistors per sensor. Given the substantially higher dielectric constant of water as compared to the air or to the insulative material (e.g., plastic) used in the wash tub, the level of fluid in the wash tub can be sensed based on the capacitance measured between the insulated wires or conductive strips.

[0073]In one embodiment, for example, a microcontroller may monitor voltage change over time and when one time constant of the RC filter has been reached (˜63% of the maximum voltage), the time to reach this voltage may be saved and used to calculate the capacitance, e.g., using the formula:

$\begin{array}{cc}C=T/R& \left(7\right)\end{array}$

where T is the time constant, R is resistance, and C is capacitance. So long as the wires are kept undisturbed to a reasonable degree, the capacitance in air or plastic will not change to a significant degree, and the insulated nature of capacitance allows for the sensors to be embedded in the walls of the wash tub or mounted outside of the wash tub, thereby isolating the sensors from possible corrosion over time. The precision of capacitive water level sensing allows for a certain water level to be dispensed during installation, and the laundry washing machine to be leveled by attempting to make the detected water levels equal at all sensor locations. It will be appreciated that other manners of determining capacitance using a capacitive sensor may be used in other embodiments, so the invention is not limited to the specific calculations discussed herein. For example, in some embodiments, the sensors can be repeatedly charged and discharged between set voltages, with the frequency measured to obtain the capacitance, while in other embodiments, a known high frequency AC signal may be passed to the sensors and the voltage and/or phase angle difference between voltage and current can be measured to obtain the capacitance.

[0074]Capacitance sensing may be implemented using two or more capacitive sensors, with each sensor generally constructed from two conductors fixed relative to each other and relative to the washer tub with geometry to improve the predictable change in capacitance. Readings may be improved with calibration and proper selection of wire insulation and the plastic they are embedded in (regarding the dielectric constant of the materials, low constant between the wires, high constant for wire insulation). There may also be geometry designs in the wash tub to reduce sensor noise from water sloshing on the wall of the sensor, like baffles in tanks. In addition, one or more extra capacitive sensors may be used in some embodiments to reduce sensor noise, e.g., by detecting and directly accounting for environmental capacitive noise.

[0075]FIG. 10, for example, illustrates an example wash tub 180 including a plurality of (e.g., four) capacitive sensors 182 disposed on a side wall thereof. Each capacitive sensor may be formed, for example, using a pair of conductive strips 184, 186 embedded in a wall of the wash tub or alternatively mounted thereto (e.g., on an inner or outer wall surface thereof). In general, it is desirable for long term performance to isolate the sensors from exposure to the interior of the wash tub, as otherwise long-term exposure to detergent and loads could otherwise cause wear on the sensors.

[0076]In addition, rather than using a pair of parallel wires or strips, in some embodiments, other capacitive arrangements may be used, e.g., where one strip 184 running substantially vertically along the wash tub wall forms one “plate” of the capacitor while the other “plate” is formed by a conductive material 188 formed on the bottom of the wash tub. It will be appreciated that capacitance may be measured between two conductive materials disposed in a number of different relative orientations, so long as the capacitance between the conductive materials varies with water level in the wash tub, a wide variety of conductive material sizes, thicknesses, placements, and orientations may be used to form a capacitive level sensor consistent with the invention.

[0077]Calibration and leveling operations may be performed using capacitive sensors in substantially the same manner as with load cell level sensors, e.g., using the operations described above in connection with FIGS. 6 and 7, and with predetermined amounts of water dispensed into the wash tub to allow for fluid level to be sensed by each capacitive sensor. In addition, similar level state determinations to those described above in connection with a wash cycle (e.g., as shown in FIG. 9) may also be performed using capacitive sensors. In addition, capacitive sensors may also be used for additional purposes during a wash cycle. For example, capacitive sensors may be used to determine the fluid level in the wash tub, thereby potentially eliminating the need for a separate fluid level sensor such as a pressure sensor 64. In addition, capacitive sensors may also be used in some embodiments to measure moisture levels in a load within the wash tub, e.g., to detect latent moisture in a load after draining the wash tub, which may be used in the determination of a fabric type for the load (given that natural fibers such as cotton generally absorb more moisture than synthetic fibers).

[0078]For example, FIG. 11 illustrates an operational sequence 200 for performing a wash cycle using a laundry washing machine incorporating capacitive level sensors. At the start of the wash cycle, a predetermined amount of water may be dispensed into the wash tub and capacitive sensor values may be captured in block 202. Then, in block 204 a level state of the laundry washing machine may be determined using the sensor values, and block 206 may determine if a level error criterion has been met. The level error criterion may be configured to inhibit initiation of a wash cycle if it is determined that the level state is excessively unlevel, and as such, if the criterion is met, control may pass to block 208 to notify the user (e.g., via a display, a mobile app, a notification, etc.) of the need to level the laundry washing machine.

[0079]If the level error criterion is not met, however, control passes to block 210 to determine a spin profile for the wash cycle, similar to block 172 of FIG. 9. Next, in block 212, additional wash cycle parameters are determined, e.g., load type, wash and/or rinse operation types, durations, repetitions, etc., using various operations that will be apparent to those of ordinary skill in the art having the benefit of the instant disclosure. At least some of these parameters may be determined at least in part using the capacitance determined using capacitive sensor values, e.g., by draining the wash tub and sensing the latent moisture in the load after draining to detect the absorption level of the load. Then, in block 214, the wash cycle is performed, using the various parameters and profiles determined above. In addition, the capacitive sensors may also be monitored during the wash cycle to control water levels and/or determine residual moisture in the load. Thus, it will be appreciated that the capacitive sensor values may be used for purposes beyond determining a level state of the laundry washing machine in some embodiments.

[0080]FIGS. 12-15 illustrate a number of alternate capacitive sensor designs that may be sued in other embodiments. FIG. 12, for example, illustrates a wash tub 220 with a four horizontally-oriented capacitive strips 222 and corresponding ground strips 224 forming four horizontally-oriented capacitive sensors, coupled with a single vertically-oriented pair of capacitive and ground strips 226, 228 forming a single vertically-oriented capacitive sensor. FIG. 13 illustrates a similar wash tub 230, having a single vertically-oriented capacitive sensor formed by a pair of capacitive and ground strips 232, 234, and a set of four horizontally-oriented capacitive strips 236. Rather than separate horizontally-oriented ground strips, however, a single ground strip 238 circumscribes the wash tub. FIG. 14 illustrates another wash tub 240 including a single vertically-oriented capacitive strip 242 and a set of four horizontally-oriented capacitive strips 244, but with a ground plate 246 disposed on the bottom of the wash tub.

[0081]In each of these designs, water fill level may be sensed using the vertically-oriented capacitive sensor, while the level state of the wash tub may be determined by filling the wash tub until an average of the four horizontally-oriented capacitive sensors reads about halfway into the sensors' sensing range, with the level state determined using a comparison of the capacitive readings of each sensor at that fill level. It will be appreciated that the signal to noise ratio of the horizontally-oriented sensors is generally higher due to the orientation of the sensors, facilitating level measurements. In addition, these designs have an additional benefit that the water fill level sensed by the vertically-oriented capacitive sensor can be calibrated during a fill by sensing when the water level crosses the horizontally-oriented capacitive sensors.

[0082]FIG. 15 illustrates a wash tub 250 having a pair of vertical strips 252, 254 forming a vertically-oriented capacitive sensor and a pair of horizontal strips 256, 258 forming a horizontally-oriented capacitive sensor. In addition, a set of measurement points 260 are defined to enable the resistance of the strips to be used to determine capacitance in each of four quadrants of the wash tub.

[0083]FIG. 16 illustrates a portion of another wash tub 270 that includes architectural features such as ribs 272 that allow for increased surface area for a pair of conductive strips 274, 276, thereby increasing the signal to noise ratio. The strips may be mounted on the inner or outer surface of the wall in various embodiments, and the ribs may project inwardly into the wash tub in other embodiments. Additional variations, e.g., decreasing the thickness of the wash tub wall, providing active or passive shielding behind the sensor, providing additional strips to sense environmental noise, etc. may also be used.

[0084]It will be appreciated that, while certain features may be discussed herein in connection with certain embodiments and/or in connection with certain figures, unless expressly stated to the contrary, such features generally may be incorporated into any of the embodiments discussed and illustrated herein. Moreover, features that are disclosed as being combined in some embodiments may generally be implemented separately in other embodiments, and features that are disclosed as being implemented separately in some embodiments may be combined in other embodiments, so the fact that a particular feature is discussed in the context of one embodiment but not another should not be construed as an admission that those two embodiments are mutually exclusive of one another. Various additional modifications may be made to the illustrated embodiments consistent with the invention. Therefore, the invention lies in the claims hereinafter appended.