JET PUMP WITH INTEGRATED DIAPHRAGM VALVE FOR OIL DRAINAGE IN A CRANKCASE VENTILATION SYSTEM OF AN INTERNAL COMBUSTION ENGINE

CROSS REFERENCE TO RELATED APPLICATION

[0001]This claims the benefit of German Patent Applications DE 10 2024 134 439.3, filed on Nov. 22, 2024 and which is hereby incorporated by reference herein.

TECHNICAL FIELD

[0002]The present disclosure relates to a jet pump for oil drainage in a crankcase ventilation system of an internal combustion engine, comprising an inlet opening for supplying oil from an oil separator of the internal combustion engine, a driving nozzle for supplying a driving medium, an outlet opening for recirculation of the oil to a cylinder head chamber of the internal combustion engine, and a non-return valve arranged at the inlet opening to prevent a backflow of oil.

BACKGROUND

[0003]During the operation of an internal combustion engine, small quantities of combustion gases, so-called blowby gases, can escape from the cylinder head chamber past the piston rings into the crankcase. Blowby gases consist mainly of unburned fuel residues and air, contaminate the engine oil and thus impair lubrication. A crankcase ventilation system feeds the blowby gases back into the cylinder head chamber to be reused for the combustion process together with fresh air. Oil separators or filters are used to remove oil vapors from the blowby gases before they are returned to the intake tract.

[0004]Jet pumps of the type mentioned above are used to recirculate oil separated from the blowby gas to the cylinder head space of the combustion engine. For this purpose, jet pumps have an inlet opening for supplying the oil and a driving nozzle for supplying a driving medium. The driving medium flows through the driving nozzle at high speed and sucks in the oil due to the resulting vacuum. The driving medium and the oil are fed out of the jet pump through an outlet opening. A non-return valve is provided to prevent oil from flowing back through the inlet opening.

[0005]DE 11 2014 005 241 B4, for example, shows a crankcase ventilation system with a crankcase ventilation filter drain and a pressurized oil supply. A nozzle is coupled to the pressurized oil supply and is configured to form an oil jet opposite an outlet of the crankcase ventilation filter drain. Further, a valve is coupled to the crankcase breather filter drain and configured to prevent collected oil from entering the crankcase ventilation filter drain through an opening. To block the opening, the valve has a ball or disk with a lower density than oil, which floats in the crankcase ventilation filter drain when a threshold amount of oil is exceeded and blocks the opening.

SUMMARY

[0006]An aspect of the present disclosure is to provide a jet pump for oil drainage in a crankcase ventilation system that easily provides improved and reliable sealing during oil backflow.

[0007]This object is achieved by a jet pump for oil drainage in a crankcase ventilation system of an internal combustion engine with an inlet opening for supplying oil from an oil separator of the internal combustion engine and a driving nozzle for supplying a driving medium. The jet pump has an outlet opening for recirculating the oil to a cylinder head chamber of the internal combustion engine and a non-return valve arranged at the inlet opening to prevent a return flow of oil. The non-return valve is designed as a diaphragm valve.

[0008]The diaphragm valve enables reliable sealing of the inlet opening of the jet pump. The use of the diaphragm valve ensures that the inlet opening is closed by the diaphragm of the valve and is only opened by the oil pressure of the separated oil in front of the inlet opening. By opening the diaphragm valve only to allow oil to pass into the jet pump, and not first to close it in order to prevent backflow of oil through the inlet opening, as is the case, for example, with a floating ball or disc, the amount of backflowing oil can be minimized. This enables better sealing of the jet pump.

[0009]A jet pump is a device that uses the principle of jet propulsion to convey a medium, for example a fluid such as a gas or a liquid. The jet pump has an inlet opening for supplying the pumped medium in the form of oil from the oil separator of the internal combustion engine. The jet pump has a driving nozzle for supplying a driving medium, for example oil or air. The driving nozzle is designed such that the driving medium is accelerated, in particular compressed, sucks in the oil due to the resulting negative pressure and transports it in the direction towards the outlet opening, in particular entrains it. The oil can be fed back into the internal combustion engine's cylinder head chamber via the outlet opening.

[0010]The diaphragm valve is located at the inlet opening. In addition, the diaphragm valve can have a diaphragm housing and a diaphragm arranged on it. The diaphragm can be adjusted between an open position that releases the inlet opening and a closed position that seals the inlet opening in a fluid-tight manner. The diaphragm housing can be designed in such a way that the diaphragm is surrounded by the housing in the circumferential direction of a longitudinal axis of the diaphragm housing. The diaphragm housing can be cup-shaped. For example, the diaphragm housing can be designed as a cylindrical chamber with a wall extending along the longitudinal axis of the diaphragm housing between a base face and a contact face.

[0011]The diaphragm housing can have one or more openings to allow the oil to pass through in the open position. In particular, the openings can be arranged on the base face of the diaphragm housing. The openings can be arranged randomly or in a pattern, for example distributed in a circumferential direction around the longitudinal axis of the diaphragm housing at a distance from each other. For example, the diaphragm housing, in particular the base face of the diaphragm housing, can have at least two, at least three or at least four openings. In particular, the diaphragm housing can have four to ten, four to nine or four to eight openings. For example, the diaphragm housing can have six openings to allow the oil from the oil separator to pass through.

[0012]The diaphragm can be arranged in the diaphragm housing. The diaphragm can be preloaded in the direction towards the closed position, in particular by a spring. Furthermore, the diaphragm can be secured in the base face of the diaphragm housing to prevent it from moving in the direction of the longitudinal axis of the diaphragm housing. The diaphragm and/or the diaphragm housing can be designed in such a way that a positive fit is formed between the diaphragm and the diaphragm housing. For example, the diaphragm housing can have a through opening extending in the direction along the longitudinal axis of the diaphragm housing. The diaphragm can have a cylindrical section adapted to the diameter of the through opening and a disk connected to the cylindrical section. The disk can have a larger diameter at the base face of the diaphragm housing than the through opening in order to form the positive fit in the direction along the longitudinal axis of the diaphragm housing. Alternatively, the through-opening can be arranged on the diaphragm, with the cylindrical section and the disk being formed on the diaphragm housing.

[0013]According to a possible further development, the driving nozzle can be designed to supply charge air from the internal combustion engine as a driving medium. When the jet pump is installed, the driving nozzle can be connected to the engine to supply charge air. For example, the charge air can be discharged to the jet pump after an exhaust gas turbocharger. Preferably, the driving nozzle can be arranged between the inlet opening and the outlet opening. The driving nozzle can be arranged in the flow direction of the oil between the inlet opening and the outlet opening. In addition, the driving nozzle can be arranged in front of the outlet opening in such a way that the driving medium is conveyed in the direction towards the outlet opening. For example, the driving nozzle is arranged opposite the outlet opening.

[0014]The use of charge air as a driving medium is simple and inexpensive to implement. In the lower partial load range of the engine, however, a low charge pressure can result in no drive energy being available for the jet pump and, when the jet pump is installed in a crankcase ventilation system, oil is no longer returned to the cylinder head space. The pressure conditions in the cylinder head chamber can generate a blowby gas flow in a direction opposite to the flow direction of the oil, whereby oil is conveyed towards the inlet opening of the jet pump. With charge air as the driving medium, the diaphragm valve therefore enables a particularly effective sealing of the inlet opening, which reliably and effectively prevents the oil from flowing back through the inlet opening.

[0015]According to a possible embodiment, the inlet opening, the driving nozzle and the outlet opening can be formed by a base body. The base body can be designed in such a way that the oil enters the base body in the flow direction through the inlet opening, then flows past the driving nozzle and then leaves the base body through the outlet opening. For example, the base body can be cylindrical in shape, whereby the inlet opening and the outlet opening can each be formed at an end of the base body. The inlet opening can be arranged at a first end section of the base body. Accordingly, the outlet opening can be arranged at a second end section of the base body. The inlet opening and the outlet opening can each be formed on the end faces of the base body. The end faces can each designate a final cross-section of the base body at the first or second end section of the base body. The inlet opening can be formed on a first end face and the outlet opening can be formed on a second end face.

[0016]The base body can have an interior extending between the inlet opening and the outlet opening. The interior of the base body can be limited in a radial direction to a longitudinal axis of the base body by a cylinder wall. The driving nozzle can be arranged in the interior. For example, the driving nozzle is arranged on a projection projecting from a cylinder wall of the interior. To supply the driving medium, in particular the charge air, the driving nozzle can be connected to an air duct that passes through the cylinder wall of the base body. The inlet opening, the driving nozzle and/or the outlet opening can be arranged concentrically to the longitudinal axis of the base body, i.e. the centers of the inlet opening, the driving nozzle and/or the outlet opening are each arranged on the longitudinal axis of the base body. The design of the base body with the arrangement of the driving nozzle and the inlet and outlet openings enables a simple and low-maintenance design of the jet pump and simple supply of the driving medium into the interior of the base body.

[0017]According to a possible further development, the jet pump can have a coupling section surrounding the inlet opening for connecting the diaphragm valve to the base body. The coupling section can be designed in such a way that the diaphragm valve is connected to the base body in a force-fitting manner, for example via a press fit. The coupling section can be a free area of the base body for arranging the diaphragm valve. Furthermore, the coupling section can have a larger diameter than the rest of the interior in order to position the diaphragm valve in the base body.

[0018]The coupling section can also have a stop for positioning the diaphragm valve on the base body in order to secure the diaphragm valve against displacement in the flow direction of the oil. The first end face of the base body can be annular in the circumferential direction around the inlet opening. The stop can be arranged at a distance from the first end face in the direction along the longitudinal axis of the base body. The stop can be understood to be a support surface of the base body arranged offset to the first end face in the interior of the base body. The diaphragm valve can rest with the contact face of the diaphragm housing on the support surface.

[0019]The diaphragm valve can be connected to the base body in a materially and/or frictionally joined manner. A lateral surface of the diaphragm housing can be connected to an area of the cylinder wall of the base body between the first end face and the support surface in a positive locking and/or frictionally joined manner. An adhesive layer can be arranged between the cylindrical wall of the base body and the lateral surface of the diaphragm housing to create a material bond. Alternatively or additionally, a welded connection can also be provided. For a frictional connection, for example, the lateral surface can be adapted to the surface of the cylinder wall in such a way that a frictional connection is created between the diaphragm housing and the base body in the direction along the longitudinal axis of the base body. The diaphragm valve can be arranged reliably and compactly on the base body of the jet pump thanks to the coupling section and, in particular, the possible designs of the coupling section. An alternative or additional adhesive layer can further improve the connection of the diaphragm valve to the base body and also ensure sealing between the diaphragm valve and the cylinder wall of the base body.

[0020]The present disclosure further relates to a crankcase ventilation system of an internal combustion engine with an oil separator for separating oil from a blowby gas flow and a jet pump for recirculating the separated oil to a cylinder head chamber of the internal combustion engine. The oil separator can have a single or multi-stage design. For example, the oil separator has a pre-separator and a fine separator. The fine separator can have an outlet for discharging the blowby gas flow from the engine to the environment. The jet pump can be arranged on the crankcase. The jet pump can also be connected to the fine separator. In particular, the jet pump can be arranged on the crankcase in such a way that the inlet opening of the jet pump is connected to the fine separator in order to discharge the oil from the fine separator.

[0027]The oil is separated from the blowby gas flow in the oil separator of the crankcase ventilation system. To convey the oil from the oil separator back into the cylinder head space of the combustion engine, the separated oil is fed from the oil separator, in particular the fine separator, via the inlet opening of the jet pump. As soon as the oil pressure upstream of the inlet opening exceeds the preload force, in particular the spring force of the diaphragm, the diaphragm valve is moved from the closed position to the open position by the pressure of the separated oil. The oil can pass through the inlet opening, in particular the openings of the diaphragm housing and the diaphragm, in order to be fed to the jet pump. The driving medium is fed to the jet pump via the driving nozzle. Preferably, charge air from the engine can be used as a driving medium. Due to the high speed of the driving medium resulting from the decreasing diameter of the driving nozzle, the oil is transported from the inlet opening towards the outlet opening and returned through the outlet opening into the cylinder head chamber of the combustion engine. The non-return valve in the form of the diaphragm valve prevents the oil from flowing back through the inlet opening in the direction towards the oil separator, in particular the fine separator.

BRIEF SUMMARY OF THE DRAWINGS

[0028]An embodiment of a jet pump is explained below with reference to the drawings. The drawings show a schematic representation:

[0029]FIG. 1 shows a perspective view of a jet pump,

[0030]FIG. 2a shows a longitudinal section through the jet pump of FIG. 1 with a diaphragm valve arranged in a closed position,

[0031]FIG. 2b shows a longitudinal section through the jet pump of FIGS. 1 and 2 with the diaphragm valve arranged in an open position,

[0032]FIG. 3 shows a crankcase ventilation system of an internal combustion engine with the jet pump of FIGS. 1 to 2b, and

[0033]FIG. 4 shows steps of a method for oil drainage in the crankcase ventilation system of FIG. 3.

DETAILED DESCRIPTION

[0034]FIG. 1 shows a jet pump 1 for oil drainage in a crankcase ventilation system 2 of an internal combustion engine. The jet pump 1 has an inlet opening 3 for supplying oil from an oil separator 4 of the internal combustion engine, a driving nozzle 5 for supplying a driving medium and an outlet opening 6 for returning the oil to a cylinder head chamber 7 of the internal combustion engine in the flow direction S of the oil.

[0035]A non-return valve in the form of a diaphragm valve 8 is arranged at the inlet opening 3. As shown in FIGS. 2a and 2b, the diaphragm valve 8 has a diaphragm housing 9 and a diaphragm 10. The diaphragm housing 9 is shaped like a cup, i.e. as a cylindrical chamber, and has a wall 13 extending between its base face 11 and a contact face 12. The diaphragm 10 is arranged in the diaphragm housing 9 between the base face 11 and the contact face 12, so that the wall 13 surrounds the diaphragm 10 in the circumferential direction around a longitudinal axis LM of the diaphragm housing 9. The diaphragm 10 is secured to the base face 11 of the diaphragm housing 9 against displacement in the direction of the longitudinal axis LM of the diaphragm housing 9 by a positive fit 15. The diaphragm housing 9 has a through opening 32 extending in the direction along the longitudinal axis LM of the diaphragm housing 9. The diaphragm 10 has a cylindrical section 33 adapted to a diameter D1 of the through opening 32 and a disk 34 connected to the cylindrical section 33. The disk 34 has a larger diameter D2 on the base face 11 of the diaphragm housing 9 than the through opening 32 in order to form the positive fit 15 in the direction along the longitudinal axis LM of the diaphragm housing 9.

[0036]The diaphragm valve 8 can be adjusted between an open position as shown in FIG. 2a and a closed position as shown in FIG. 2b. In the open position, the inlet opening 3 is open to allow the separated oil to pass through and in the closed position, the inlet opening 3 is sealed fluid-tight by the diaphragm 10. The diaphragm housing 9 has several openings 14 to allow the oil to pass through in the open position. The openings are arranged on the base face 11 of the diaphragm housing 9 at a distance from each other in the circumferential direction around the longitudinal axis LM of the diaphragm housing 9.

[0037]The driving nozzle 5 is designed to supply charge air T as the driving medium. When the jet pump 1 is installed, the driving nozzle 5 for supplying the charge air T is connected to the engine. The charge air T is discharged to the jet pump 1 after an exhaust gas turbocharger, for example. Furthermore, the driving nozzle 5 is arranged in the flow direction S of the oil between the inlet opening 3 and the outlet opening 6. In addition, the driving nozzle 5 is arranged in front of the outlet opening 6 in such a way that the charge air T is conveyed in the direction towards the outlet opening 6. For example, the driving nozzle 5 is arranged opposite the outlet opening 6.

[0038]The inlet opening 3, the driving nozzle 5 and the outlet opening 6 are formed by a base body 16. The base body 16 is cylindrical in shape. The inlet opening 3 and the outlet opening 6 are each formed at an end of the base body 16. The inlet opening 3 is arranged at a first end section 17 of the base body 16 and the outlet opening 6 is arranged at a second end section 18 of the base body 16. The inlet opening 3 and the outlet opening 6 are each formed on the end faces 19, 20 of the base body 16. The end faces 19, 20 are each end cross-sections of the base body 16 at the first or second end section 17, 18 of the base body 16. The inlet opening 3 is formed on a first end face 19 of the first end section 17 and the outlet opening 6 is formed on a second end face 20 of the second end section 18. The first end face 19 of the base body 16 is annular in the circumferential direction to a longitudinal axis L of the base body 16 around the inlet opening 3.

[0039]The base body 16 also has an interior 21 extending between the inlet opening 3 and the outlet opening 6. The latter is limited in the radial direction to the longitudinal axis L of the base body 16 by a cylinder wall 22. The driving nozzle 5 is arranged on a projection 23 projecting from the cylinder wall 22 into the interior 21 of the base body 16. To supply the driving medium in the form of charge air T, the driving nozzle 5 is connected to an air duct 24 that passes through the cylinder wall 22 of the base body. The inlet opening 3, the driving nozzle 5 and the outlet opening 6 are arranged concentrically to the longitudinal axis L of the base body 16. Accordingly, the centers M1 of the inlet opening, M2 of the driving nozzle and M3 of the outlet opening 6 are each arranged on the longitudinal axis L of the base body 16.

[0040]The jet pump 1 has a coupling section 25 surrounding the inlet opening 3 for connecting the diaphragm valve 8 to the base body 16. The coupling section 25 is designed in such a way that the diaphragm valve 8 is form-fittingly connected to the base body 16. The coupling section 25 is a free area of the base body 16 for arranging the diaphragm valve 8 and has a larger diameter D than the rest of the inner space 21 of the base body 16. The coupling section 25 has a stop 26 for positioning the diaphragm valve 8 on the base body 16. The stop 26 is a support surface 27 arranged in the direction of the longitudinal axis L of the base body 16 at a distance from the first end face 19 in the interior 21. The diaphragm valve 8 rests with the contact face 12 of the diaphragm housing 9 on the support surface 27.

[0041]A lateral surface 28 of the diaphragm housing 9 is frictionally connected, for example via a press fit, to an area of the cylinder wall 22 of the base body 16 between the first end face 19 and the support surface 27. In addition to the force-fitting connection, the diaphragm valve 8 can also be connected to the base body 16 in a materially joined manner. An adhesive layer can also be arranged between the cylindrical wall 22 of the base body 16 and the outer surface 28 of the diaphragm housing to create a material bond.

[0042]FIG. 3 shows a crankcase ventilation system 2 of an internal combustion engine with an oil separator 4 for separating oil from a blowby gas flow B and a jet pump 1 for recirculating the separated oil to a cylinder head chamber 7. The oil separator 4 is multi-stage and has a pre-separator 29 and a fine separator 30. The fine separator 30 has an outlet 31 for discharging the blowby gas flow B from the engine to the environment. The jet pump 1 is connected to the fine separator 30 via the inlet opening 3 in order to remove the oil from the fine separator 30.

[0043]The process steps of a method for oil drainage in the crankcase ventilation system 2 are shown in FIG. 4. The oil from the blowby gas flow B is separated in the oil separator 4 of the crankcase ventilation system 2. The remaining blowby gas flow B from the engine is released into the environment from the outlet 31 of the fine separator 30. To convey the oil from the oil separator 4 back into the cylinder head chamber 7, the separated oil is fed from the fine separator 30 of the oil separator 4 via the inlet opening 3 of the jet pump 1. As soon as the oil pressure upstream of the inlet opening 3 exceeds the spring force on the diaphragm 10, the diaphragm valve 8 is moved by the pressure of the separated oil from the closed position as shown in FIG. 2a to the open position as shown in FIG. 2b. The oil can pass through the inlet opening 3 and the openings 14 of the diaphragm housing 9 in order to be fed to the jet pump 1. The driving medium in the form of the charge air T is fed to the jet pump 1 via the driving nozzle 5. The high velocity of the charge air T transports the oil from the inlet opening 3 towards the outlet opening 6 and returns it through the outlet opening 6 into the cylinder head chamber 7 of the internal combustion engine.

[0044]In the lower partial load range of the engine, a low charge pressure means that no drive energy is available for the jet pump 1 and there is no oil recirculation into the cylinder head chamber 7. The pressure conditions in the cylinder head chamber 7 can generate a blowby gas flow B in a direction opposite to the flow direction S of the oil, whereby oil is conveyed in the direction towards the inlet opening 3. In the closed position, the diaphragm valve 8 prevents the oil from flowing back through the inlet opening 3 in the direction of the fine separator 30.

[0045]The use of the diaphragm valve 8 ensures that the inlet opening 3 is closed by the diaphragm 10 of the valve 8 and is only opened by the oil pressure of the separated oil in front of the inlet opening 3. By opening the diaphragm valve 8 only to allow oil to pass into the jet pump 1 and not closing it to prevent oil from flowing back through the inlet opening 3, the amount of oil flowing back can be minimized for a better seal.

List of Reference Signs