Oil supply system with an oil cross member fixed between two housing parts and drive train with the oil supply system

Abstract

An oil supply system 17 for an electric drive train 1 of a vehicle is disclosed, comprising an oil sump 18, an oil pump 19 for conveying oil from the oil sump 19 along an oil flow path 20, two housing parts 22a, 22b of a transmission 3 that are connected to one another in the axial direction with respect to a rotational axis 100 of a transmission shaft 10, wherein a first housing part 22a has an oil supply opening 23 and a second housing part 22b has an oil discharge opening 24, wherein the oil flow path 20 runs from the oil supply opening 23 to the oil discharge opening 24 through the transmission 3, wherein the oil supply system 17 has an oil cross member 21 that fluidically connects the oil supply opening 23 and the oil discharge opening 24, which oil cross member has at least one oil nozzle arranged between the oil supply opening 23 and the oil discharge opening 24 25a, 25b for the targeted oil supply to an oil supply point 26a, 26b within the gearbox 3,wherein the oil cross member 21 is fixed between the two housing parts 22a, 22b.,

Description

The invention relates to an oil supply system for an electric drive train of a vehicle having the features of the preamble of claim 1.In motor vehicles, the components of the powertrain, such as the traction motor and the traction transmission, are lubricated and cooled. In order to reduce the efficiency of the oil supply and thus of the drive train, so-called dry sump lubrication is known. In this case, the gearwheels of the traction transmission do not enter the oil sump, but are actively supplied with oil. In order to ensure efficient lubrication, the oil must be supplied to the components as efficiently as possible in dry oiled systems.The document DE 10 2021 123 189 A1 discloses an electric drive unit for a vehicle, having an electric machine for generating a drive torque for the vehicle, having a transmission, wherein the transmission is operatively connected to the electric machine, such that the drive torque is introduced into the transmission, having an oil supply arrangement, wherein the oil supply arrangement has an engine supply section for supplying the electric machine and a transmission supply section for supplying the transmission with a transmission oil along a transmission supply path, wherein the oil supply arrangement has a bypass section, wherein the bypass section fluidically adjoins the transmission supply section and wherein the bypass section is fluidically arranged at least in sections parallel to the transmission supply path, and the electric drive unit has a pressure-controlled passage valve, wherein the through valve is disposed fluidly between the transmission supply portion and the bypass portion such that the bypass portion is fluidly connected to the transmission supply portion depending on an oil pressure of the transmission oil.It is an object of the present invention to propose an oil supply system which is distinguished by a particularly efficient oil distribution. It is a further object of the invention to propose a drive train with the oil supply system.This object is achieved by an oil supply system having the features of claim 1 and a drive train having the features of claim 10. Preferred or advantageous embodiments of the invention are evident from the dependent claims, the following description and the appended figures.The invention relates to an oil supply system which is designed and / or suitable for an electric drive train of a vehicle. In particular, the oil supply system serves for distributing and / or supplying, in particular for lubricating and / or cooling, the electric drive train with an oil, preferably a transmission oil. The electric drive train preferably has at least one electric machine and at least one transmission, preferably a reduction transmission, which are supplied with oil, preferably cooled and / or lubricated, via the oil supply system. The vehicle is in particular an electric vehicle. In particular, it may be a pure electric vehicle or a hybrid vehicle.The oil supply system comprises an oil sump. In particular, the oil distributed via the oil supply system is collected in the oil sump. Shown in simplified form, the oil sump forms an oil source of the oil supply system. In principle, a separate oil sump can be assigned to the transmission and the electric machine. Preferably, however, the transmission and the electric machine have a common oil sump.The oil supply system includes an oil pump configured to pump an oil from the oil sump along an oil flow path. In particular, the oil supply system has exactly one oil pump which supplies the electric machine and the transmission with the oil from the common oil sump. In a simplified illustration, the oil flow path runs via the electric machine and the transmission back into the oil sump.The oil supply system has two housing parts of the transmission which are connected to one another in the axial direction with respect to an axis of rotation of a transmission shaft. In particular, the two housing parts together form a transmission housing for the transmission. The transmission shaft can be designed as an input or output transmission shaft. Preferably, one housing part comprises a drive opening, via which a drive shaft or an input transmission shaft is guided into the transmission housing and connected in terms of drive technology to the electric machine, and the other housing part comprises at least output opening, via which an output shaft is guided out of the transmission housing and connected in terms of drive technology to a vehicle wheel or a further transmission. Optionally, the transmission comprises a transfer case, in particular a differential gear, via which the drive torque is distributed to two vehicle wheels. For this purpose, the two housing parts can each have at least one output opening, via which in each case an output shaft is guided out of the transmission housing and connected in terms of drive technology to in each case a vehicle wheel.Furthermore, one housing part has an oil feed opening and the other housing part an oil discharge opening, wherein the oil flow path runs from the oil feed opening via the oil discharge opening into the oil sump. In particular, the oil supply opening and the oil discharge opening are formed separately from the drive opening and the driven opening(s). In other words, the oil supply opening and the oil discharge opening are arranged spaced apart from the drive and output openings in the radial direction with respect to the axis of rotation. The oil supply opening and the oil discharge opening preferably have a common central axis and / or are arranged axially opposite one another and / or in alignment with one another. Particularly preferably, the oil supply opening serves for supplying oil from the electric machine or an engine housing and the oil discharge opening serves for discharging oil from the transmission or the transmission housing.Furthermore, the oil supply system has an oil cross member which fluidically connects the oil supply opening and the oil discharge opening. In particular, the oil traverse serves for the internal supply and / or distribution of oil in the transmission housing. The oil traverse preferably serves for implementing dry sump lubrication, wherein the oil can be supplied and / or is supplied continuously via the oil traverse in a targeted manner to one or more oil supply points of the transmission. Preferably, the at least one oil supply point is formed by an engagement region of two transmission wheels. Particularly preferably, the oil cross member is formed separately from the gear shaft. In other words, the oil traverse is configured to be stationary and / or fixed to the housing relative to the rotating transmission components of the transmission.The oil traverse has at least or exactly one, preferably two, oil nozzle(s) arranged between the oil supply opening and the oil discharge opening, which is / are designed and / or suitable for the targeted supply of oil to at least one oil supply point within the transmission. Preferably, both a fluidic and a mechanical connection between the two housing parts takes place via the oil traverse. The oil cross member can be fixed in the radial and axial direction with respect to the central axis in a form-fitting and / or force-fitting manner in the oil supply opening and the oil discharge opening. In particular, the oil nozzle is oriented in the radial direction or substantially in the radial direction with respect to the central axis. Here, "substantially in the radial direction" means that the oil nozzle may deviate from a radial direction in an angular range of up to + / -45 degrees.Within the scope of the invention, it is proposed that in a further development it is provided that the oil supply system has a pressure regulating valve operatively connected to the oil traverse, which pressure regulating valve is arranged fluidically between the oil supply opening and the at least one oil nozzle. The pressure regulating valve is designed to release a bypass flow path running parallel to the oil flow path when a defined oil pressure is exceeded, so that an excess of oil is discharged via the bypass flow path past the oil supply points and / or directly into the oil sump when the oil pressure is exceeded. In particular, the pressure regulating valve is arranged fluidically upstream of the oil nozzle(s), so that a portion of oil can be discharged directly downstream of the oil feed opening. Specifically, the pressure control valve serves to implement minimum amount lubrication. The pressure regulating valve is in particular designed as a mechanically controlled, in particular a pressure-mechanically controlled pressure regulating valve. Particularly preferably, the pressure regulating valve is designed as a throttle.The invention is based on the finding that the volume flow delivered by the oil pump, in the case of combined systems of electric machine and transmission, is critically dependent on the cooling requirement of the electric machine. In this case, the cooling or lubrication requirement of the transmission can be different from that of the electric machine, so that an oversupply of the transmission occurs in the event of an increased cooling requirement of the electric machine. The pressure regulating valve prevents an excess amount of oil from reaching the rotating transmission components, thereby avoiding increased splashing and crushing losses in the transmission. In addition, an oil supply within the drive train is realized with the simplest possible means and the advantages of dry sump lubrication. By means of the oil cross bar, a particularly simple and flexible oil supply can be realized within the transmission. Since the oil cross member is formed separately from the transmission shaft, it can be arranged at any desired location within the transmission housing, whereby a particularly precise oil supply to the oil supply locations is made possible. Furthermore, the transmission shaft can be designed particularly simply and cost-effectively in comparison with the prior art, in which an oil is supplied via a transmission shaft designed as a hollow shaft.In a concrete embodiment, it is provided that the oil cross member and the pressure regulating valve form a common and / or self-holding structural unit. The pressure regulating valve is preferably mounted on the oil cross member in a captive manner, preferably in a positively locking and / or non-positively locking manner. Preferably, the pressure regulating valve is mounted coaxially and / or concentrically on the oil traverse. A particularly compact integration of the pressure regulating valve on the oil cross member is thus proposed, as a result of which particularly simple assembly and handling is made possible.In a further specific embodiment, it is provided that the pressure regulating valve has a cylinder housing fixed to the oil cross member, a cylinder piston guided within the cylinder housing along the oil cross member so as to be displaceable between a closed position and a release position, and a restoring spring which applies a spring force to the cylinder piston in the direction of the closed position, wherein the cylinder housing has at least or exactly one bypass opening which is closed in the closed position of the cylinder piston and released in the release position of the cylinder piston. In particular, the defined oil pressure is determined by the spring force, so that the cylinder piston can be displaced between the closed position and the release position as a function of the prevailing oil pressure. The restoring spring is preferably designed as a compression spring which is supported in the axial direction between the cylinder piston and the cylinder housing. The cylinder piston can assume a plurality of release positions which release a different opening cross section of the bypass opening depending on the displacement path. In other words, the release position is to be understood as any desired piston position in which the bypass opening is at least partially opened. Preferably, the cylinder housing and the cylinder piston are mounted coaxially and / or concentrically on the oil traverse with respect to the longitudinal axis or center axis. In particular, a cylinder piston is understood to mean a cylindrical piston which is designed and / or suitable for axial guidance along the oil traverse. The bypass opening can be designed as a radial bypass opening, so that the oil exits along the bypass flow path radially at the cylinder housing. Alternatively, the bypass opening or optionally additionally or a further bypass opening is designed as an axial bypass opening, so that the oil exits axially at the cylinder housing along the bypass flow path. In particular, the cylinder housing can have a plurality of radial and / or axial bypass openings distributed in the circumferential direction. A pressure regulating valve is thus proposed, which can be mounted or integrated on the oil cross member in a simple manner in a space-saving manner.In a further concretization, it is provided that the oil traverse has a straight pipe piece which fluidically connects the oil feed opening and the oil discharge opening in the axial direction with respect to its longitudinal axis or the central axis, wherein the cylinder housing is fixed to the pipe piece and the cylinder piston is guided linearly along the pipe piece. Preferably, the cylinder piston is linearly guided and / or positively guided on an outer circumference of the pipe piece so as to be displaceable in the axial direction with respect to the longitudinal axis or central axis. Specifically, this means that the cylinder piston is designed as a hollow cylinder and / or a cylinder sleeve with a central receiving opening, through which the pipe piece is guided in the axial direction and / or is received in a form-fitting manner in the radial direction. The pipe piece is preferably arranged radially inside the cylinder housing and the cylinder piston. The pipe piece is preferably produced from a plastic, preferably a plastic injection molding. In principle, the at least one oil nozzle can be designed as a separate component which is connected to the pipe piece in a force-fitting and / or materially integral manner. Alternatively, however, the pipe piece and the at least one oil nozzle can also be produced from a common material section, preferably a common plastic injection molding. Particularly preferably, the oil traverse is formed substantially by the pipe section and the at least one oil nozzle. A particularly simple and compact construction is thus proposed.In a further development, it is provided that the pipe piece is fixed between the two housing parts, wherein the longitudinal axis is arranged axially parallel and / or axially offset to the axis of rotation. In other words, the pipe piece is arranged parallel and / or in the same direction as the transmission shaft or the axis of rotation in the transmission housing. Preferably, the oil supply opening and the oil discharge opening are each designed as a bore, wherein the pipe piece is inserted into the respective bore in the axial direction with respect to the longitudinal axis. In particular, the pipe piece has a through opening connecting the oil supply opening and the oil discharge opening in the axial direction with respect to the longitudinal axis. In particular, the oil cross member is clamped between the two housing parts in the axial direction with respect to the central axis. This allows particularly simple installation of the oil cross member between the two housing parts.In a further refinement, it is provided that the cylinder housing defines an inlet opening, wherein the oil cross member is arranged within the inlet opening, forming an annular space. Shown in simplified form, the oil traverse or the pipe piece has a smaller diameter than the cylinder housing and / or is arranged radially spaced apart from the cylinder housing. According to this specification, it is provided that the annular space is axially delimited by a piston crown of the cylinder piston. The piston surface is preferably designed as an annular surface encircling the oil cross member. In particular, a dynamic pressure surface is defined on the one hand by the piston crown or the annular space and on the other hand by the oil cross-member or the through-opening. In other words, an input-side oil pressure or dynamic pressure is dependent on the one hand on the outlet geometry of the oil cross member, in particular the opening diameter of the through opening and / or of the at least one oil nozzle, and on the other hand on the piston surface of the piston crown, wherein the cylinder piston is displaced into the release position when a corresponding design limit of the restoring spring is exceeded. Thus, in the case of an increased oil supply, for example due to an increased cooling requirement of the electric machine, on the one hand a constant and / or permanent oil supply of the oil supply point(s) can be ensured, wherein at the same time an oversupply of the oil supply point(s) is prevented if the design limit is exceeded. The oil supply points can thus be supplied with oil as required.In a further refinement, it is provided that the cylinder piston has an annular space stage and a guide stage, wherein the cylinder piston forms, with the annular space stage within the annular space, an annular channel which is axially delimited by the guide stage and connects the oil feed opening fluidically to the bypass opening at least in the release position. Shown in simplified form, the cylinder piston is of stepped diameter to form the annular space and the guide step. Preferably, the annular space step has a smaller outer diameter than the guide step. In particular, the bypass opening is completely covered by the guide step in the closed position and / or opens at least partially or in sections into the annular channel in the release position. The cylinder piston can be guided with the guide step on an inner circumferential surface of the valve housing and / or be accommodated with an exact fit in the cylinder housing. Particularly preferably, cylinder pistons and / or the cylinder housing can be produced by forming techniques. A pressure regulating valve is thus proposed, which is distinguished by a particularly simple and cost-effective construction and a small number of components.In a further embodiment, it is provided that the cylinder housing has a first connecting piece at the end, which is inserted in a sealing manner in the oil supply opening. Furthermore, the oil cross member has a second connecting piece which is inserted in a sealing manner in the oil discharge opening. In particular, a plug connection is formed between the oil cross member and the respective oil opening by the connecting pieces. The plug connection is preferably designed as a detachable plug connection, which is formed during the assembly of the two housing sections and is canceled during the disassembly of the housing sections. A fluidic connection between the two housing parts or the oil guide openings is thus proposed, which is distinguished by a particularly simple assembly. The plug connection also makes it possible to secure the oil cross member and the pressure regulating valve in a simple manner, preferably without additional fastening means, within the transmission housing.In a further concretization, it is provided that the oil flow path downstream of the pressure regulating valve is divided into a plurality of partial flow paths which serve in particular for the targeted oiling of one or more transmission components of the transmission. For example, a first partial flow path runs via a first nozzle to a first oil supply point, in particular a first engagement region, a second partial flow path runs via a second nozzle to a second oil supply point, in particular a second engagement region, and a residual flow path runs via the oil discharge opening into the oil sump. Optionally, the oil flow path can be divided into further partial flow paths already upstream of the oil supply opening and / or downstream of the oil discharge opening for oiling the further oil supply points, in particular bearing points. The bearing point can be defined, for example, by at least one rolling bearing for rotatably mounting a shaft, preferably at least one transmission shaft. The transmission preferably has a plurality of transmission shafts which are rotatably mounted on the two housing parts via a bearing point in each case, wherein at least or exactly one further partial flow path is assigned to each bearing point. This realizes a particularly simple and compact oil supply within the transmission housing.A further subject matter of the invention relates to an electric drive train having at least or exactly one electric machine, a transmission and having the oil supply system for supplying oil to the electric machine and the transmission, as have already been described above. In particular, the electric machine has a stator and a rotor, wherein the oil flow path preferably runs over the stator, for example a plurality of cooling channels formed in the stator and / or a cooling jacket. Preferably, the oil flow path extends from the oil sump, across the stator and optionally the oil inlet to the oil supply opening.Further features, advantages and effects of the invention will become apparent from the following description of preferred exemplary embodiments of the invention. The following shows: FIG. 1 shows a schematic illustration of a drive train with an oil supply system as an exemplary embodiment of the invention; FIG. 2 shows a lateral illustration of an alternative embodiment of the oil cross member with a pressure regulating valve in a sectional illustration; FIG. 3 shows a perspective illustration of an installation situation of the oil cross member from FIG. 3 on a first housing part of a transmission housing; FIG. 4 shows a perspective illustration of an installation situation of the oil cross member from FIG. 3 on a second housing part of the transmission housing.FIG. 1 shows a schematic illustration of an electric drive train 1, which is designed and / or suitable for driving a vehicle, not illustrated. In the exemplary embodiment shown, the electric drive train 1 serves for driving two driven vehicle wheels, not shown, of a common axle of the vehicle.The electric drive train 1 has an electric machine 2 and a transmission 3. The electric machine 2 is designed as a traction machine, which provides a drive torque for the vehicle wheels. The transmission 3 is designed as a traction transmission, which transfers the drive torque and distributes it to the two vehicle wheels. For this purpose, the electric machine 2 is operatively connected to the transmission 3, so that the drive torque can be conducted from the electric machine 2 into the transmission 3.The electric machine 2 has a stator 4 and a rotor 5 arranged radially inside the stator 4, which are arranged inside a machine housing 6. The stator 4 is connected to the machine housing 6 in a rotationally fixed manner, whereas the rotor 5 is mounted rotatably in the machine housing 6 relative to the stator 4.The transmission 3 comprises a reduction transmission 7 and a transfer transmission 8, which are arranged within a transmission housing 9. The reduction gear 7 serves to reduce the drive speed or to increase the drive torque, and the transfer gear 8 serves to distribute the drive torque to the two vehicle wheels. For example, the reduction gear 7 is designed as a two-stage spur gear and the transfer case 8 as a differential gear.The electric machine 2 has a drive shaft 10 which is connected to the rotor 5 in a rotationally fixed manner and at the same time forms an input shaft of the transmission 3, preferably of the reduction transmission 7. Furthermore, the transmission 3 has two output shafts 11 a, 11 b, which transmit the transmitted and distributed drive torque from the electric machine 2 to the two vehicle wheels and at the same time each form an output shaft of the transmission 3, preferably of the transfer transmission 8. In addition, the reduction gear 7 has an intermediate shaft 12 which is connected in terms of transmission via a first gear stage 13 ato the drive shaft 10 and via a second gear stage 13 bto the two output shafts 11 a, 11 b. For example, the first and the second transmission stage 13 a, 13 bare each formed by a spur gear stage.The drive shaft 10 is rotatably mounted on the machine housing 6 and the transmission housing 9 via three drive shaft bearings 14 a, 14 b, 14 c. In addition, the intermediate shaft 12 is rotatably mounted on the transmission housing 9 via two intermediate shaft bearings 15 a, 15 band the output shafts 11 a, 11 bare each rotatably mounted on the transmission housing 9 via an output shaft bearing 16 a, 16 b. The bearings 14 a, 14 b, 14 c, 15 a, 15 b, 16 a, 16 bmay each be formed, for example, by a rolling bearing.The electric drive train 1 has an oil supply system 17 which supplies the electric machine 2 and the transmission 3 with an oil, preferably a transmission oil, for lubrication and / or cooling. The oil supply system 17 serves for implementing a dry sump concept, in which the cooling of the electric machine 2 is connected to the cooling and lubrication of the transmission 3.The oil supply system 17 comprises an oil sump 18 as an oil source, in which an oil spun off and / or dripping off in the motor housing 6 and the transmission housing 9 is collected. To implement dry sump lubrication, the engine housing 6 and the transmission chamber 9 are connected in terms of flow to the oil sump 18 via an oil drain, not shown. Shown in simplified form, the electric machine 2 and the transmission 3 have a common oil sump 18.Furthermore, the oil supply system 17 has an oil pump 19 which is designed to convey oil from the oil sump 18 along an oil flow path 20 through the electric machine 2 and the transmission 3. For this purpose, the oil flow path 20 runs essentially from the oil sump 18 via the electric machine 2 and the transmission 3 back into the oil sump 18. Within the electric machine 2, the oil flow path 20 runs for the most part in the direction of the transmission 3 via a groove cooling formed in the stator 4.The oil supply system 17 has an oil cross rail 21 arranged within the transmission housing 9, which conveys the oil from one side of the transmission housing 9 to the other side and distributes it in a targeted manner within the transmission housing 9. The transmission housing 9 has two housing parts 22 a, 22 bconnected to one another in the axial direction with respect to an axis of rotation 100 of the drive shaft 10. For example, the first housing part 22 aconstitutes a transmission bell and the second housing part 22 bconstitutes a bearing shield of the machine housing 6. the oil cross-member 21 is stationary and / or is arranged fixed to the housing relative to the rotating transmission components, such as the drive shaft 10, the intermediate shaft 12 and the output shafts 11 a, 11 b, wherein the oil cross-member 21 is fixedly braced for this purpose in the axial direction relative to the axis of rotation 100 between the two housing parts 22 a, 22 b.In order to establish the oil flow between the two housing parts 22 a, 22 b, the first housing part 22 acomprises an oil feed opening 23 and the second housing part 22 bhas an oil discharge opening 24, which are connected to one another in terms of flow via the oil cross member 21. For distributing the oil within the transmission housing 9, the oil cross member 21 in the exemplary embodiment shown has two oil nozzles 25 a, 25 bto guide a partial quantity of oil selectively to a respective oil supply point 26 a, 26 bwithin the transmission housing 9. For example, the first oil supply point 26 ais defined by an engagement region of the first transmission stage 13 aand the second oil supply point 26 bis defined by an engagement region of the second transmission stage 13 b.The first housing part 22 aincludes a central oil inlet 27, from where the oil from the electric machine 2 is distributed in the transmission 3. For this purpose, the central oil inlet 27 is fluidically connected to the oil feed opening 23 via at least one oil duct 28 aformed in the first housing part 22 a. Thus, the oil flow path 20 runs from the oil pump 19 via the stator 4 to the oil inlet 27 and can then run via the oil duct 28 a, optionally with the interposition of a heat exchanger, to the oil feed opening 23.The second housing part 22 bhas a plurality of oil outlets 29 a, 29 b, 29 c, from where a residual quantity of oil is conducted to further oil supply points 30 a, 30 b, 30 cand is subsequently discharged into the oil sump 18. For this purpose, the oil outlets 29 a, 29 b, 29 care fluidically connected to the oil discharge opening 24 via at least one oil duct 28 bformed in the second housing part 22 b. Thus, the oil flow path 20 downstream of the oil supply opening 23 divides into a plurality of partial flow paths via the nozzle 25 a, 25 band the oil outlets 29 a, 29 b, 29 cin order to supply the various oil supply points 13 a, 13 b, 30 a, 30 b, 30 cwith a partial amount of oil. For example, the further oil supply points 30 a, 30 b, 30 cmay each be defined as a bearing point of the input shaft bearing 14 b, the intermediate shaft bearing 15 band the output shaft bearing 16 b. Correspondingly, the second housing part 22 bmay also be provided with one or more oil outlets, but not shown here, in order to supply further oil supply points, such as the bearing points of the drive shaft bearing 14 a, the intermediate shaft bearing 15 aand the output shaft bearing 16 awith a partial amount of oil.FIG. 2 shows a preferred embodiment of the oil traverse 21, The oil traverse 21 has a straight pipe piece 31 which defines a longitudinal axis 101. The pipe piece 31 has a through-opening 32 which connects the oil feed opening 23 and the oil discharge opening 24 and passes through the pipe piece 31 coaxially with respect to the longitudinal axis 101. In an intended installation situation, the pipe piece 31 is arranged with the longitudinal axis 101 axially parallel to the axis of rotation 100 within the transmission housing 9, wherein the oil flow path 22 runs substantially via the through-opening 32 from the oil feed opening 23 to the oil discharge opening 24.The two oil nozzles 25 a, 25 bare arranged substantially radially on the pipe piece 31. In this case, the first oil nozzle 25 acan be radially oriented perpendicularly to the longitudinal axis 101 and the second oil nozzle 25 bcan be radially oriented at an angle to the longitudinal axis 101, for example at an angle of approximately 60°.The volume flow conveyed along the oil flow path 20 is critically dependent on the cooling requirement of the electric machine 2 in combined systems, so that the volume flow is correspondingly increased in the case of an increased cooling requirement. The cooling and lubrication requirements of the transmission 3 can, however, be different from those of the electric machine 2, as a result of which an oversupply of oil to the transmission 3 can occur in certain operating situations. It is therefore expedient to discharge a portion of the volume flow directly before distribution to the corresponding oil supply points 13 a, 13 b, 30 a, 30 b, 30 c. Due to the one-sided arrangement of a pressure regulating valve 35 on the oil cross member 21, the oil pressure downstream of the oil supply opening 23 also abuts on the pressure regulating valve 35. At a predeterminable oil pressure, the pressure regulating valve 35 opens, as a result of which excess oil is discharged, for example, directly into the oil sump 18.Thus, an unnecessary amount of oil is prevented from being supplied to the rotating transmission components, whereby churning and crushing losses in the transmission 3 can be significantly reduced.For this purpose, the pressure regulating valve 35 is arranged in terms of flow between the oil supply opening 23 and the two oil nozzles 25 a, 25 bin an intended installation situation of the oil cross member 21 in order to release a bypass flow path 36 running parallel to the oil flow path 20 when the defined oil pressure is exceeded, such that an excess amount of oil is conducted past the oil supply points 13 a, 13 b, 30 a, 30 b, 30 cvia the bypass flow path 36.For this purpose, the pressure regulating valve 35 has a cylinder housing 37 arranged coaxially with the longitudinal axis 101 and a cylinder piston 38 arranged within the cylinder housing 37, which is mounted on an outer circumference of the pipe piece 31 so as to be displaceable in the axial direction with respect to the longitudinal axis 101 between a closed position 102 and a release position 103. The cylinder housing 37 has at least one bypass opening 39, which is closed in the closed position 102 and at least partially opened in the release position 103. By way of example, the bypass opening 39 is designed as a radial bore.The cylinder piston 38 is acted upon in the direction of the closed position 102 by a spring force via a restoring spring 40, which spring force is supported on the cylinder piston 38 on the one hand in the axial direction and on a cylinder cover 41 connected to the cylinder housing 37 in a positive and / or non-positive manner on the other hand. For example, the restoring spring 40 is designed as a helical compression spring which is arranged coaxially with respect to the longitudinal axis 101. The cylinder housing 37 is fixed in a form-fitting manner on an outer circumference of the pipe piece 31 via the cylinder cover 41 at least in the axial direction with respect to the longitudinal axis 101. Optionally, one or more pressure compensation openings, not shown, can be arranged in the cylinder cover for pressure compensation. This can be advantageous, in particular in the case of low spring stiffnesses, so that the restoring spring 40 resets the cylinder piston 38 correctly again. The pressure compensation opening(s) can be designed, for example, as bores or recesses.The pressure regulating valve 35 is arranged on one side on the oil cross member 21, wherein a first connecting piece 33 ais formed directly on the cylinder housing 37 and a second connecting piece 33 bis formed directly on the pipe piece 31. During the assembly of the transmission 3, the pressure control valve 35 is mounted on the oil cross member 21 in a captive manner, so that these form a pre-assembled structural unit. The pre-assembled structural unit can then be inserted between the two housing parts 22 a, 22 b. For this purpose, the cylinder housing 37 with the first connecting piece 33 ais inserted into the oil feed opening 23 in a sealing manner and the pipe piece 31 with the second connecting piece 33 bis inserted into the oil discharge opening 24 in a sealing manner. On each of the first and second connecting pieces 33 a, 33 b, a sealing ring 34 a, 34 bis arranged, which seals the respective connecting piece 33 a, 33 bfrom the associated housing part 22 a, 22 b.The cylinder housing 37 here defines a common inlet opening 42 for the pressure regulating valve 35 and the pipe piece 31, wherein the pipe piece 31 is arranged radially inside the inlet opening 42 forming an annular space 43. For this purpose, the inlet opening 42 has a larger diameter than the through opening 32. The annular chamber 43 is thus bounded in the radial direction on the one hand by the cylinder housing 37 and on the other hand by the tubular piece 31. The annular chamber 43 is delimited in the axial direction by a piston crown 44 of the cylinder piston 38, so that in an installed situation, the latter is acted upon by an oil pressure and, when the spring force is exceeded, is displaced in the direction of the release position 103.The cylinder piston 38 is designed as a stepped cylinder sleeve, the cylinder jacket of which has an annular space step 45 and a guide step 46. Here, the annular chamber step 45 directly adjoins the piston crown 44 and the guide step 46 adjoins the annular chamber step 45 via a radial shoulder. The cylinder piston 38 bears radially against an inner periphery of the cylinder housing 37 via the guide step 46, wherein an annular channel 47 is formed within the annular chamber 43 by the annular chamber step 45, which annular channel is axially delimited by the guide step 46.In the closed position 102, the cylinder piston 38, in particular the piston crown 44, is supported on the cylinder housing 37 in the axial direction with respect to the longitudinal axis 100 and the bypass opening 39 is covered by the guide step 46, so that oil can flow exclusively via the through opening 32 along the oil flow path 20. After the pressure regulating valve 35, the oil flow path 20 divides into a plurality of partial flow paths 48 a, 48 b, 48 c, wherein a first partial flow path 48 aextends via the first nozzle 25 a, a second partial flow path 48 bextends via the second nozzle 25 band a third partial flow path 48 cextends via the through opening 32. In this case, due to the invariable outlet geometry of the oil traverse 31, a system pressure is established which works against the restoring spring 40. If a corresponding design limit of the restoring spring 40 is exceeded, the cylinder piston 38 moves in the direction of the release position 103 and at least partially releases the bypass opening 39, so that oil can flow parallel to the oil flow path 20 via the annular channel 47 and the bypass opening 39 along the bypass flow path 36. Thus, the system pressure can be maintained at a constant pressure level with an increased cooling requirement of the electric machine 1, or a constant or limited volume flow can be set along the partial flow paths 48 a, 48 b, 48 c.For guiding the cylinder piston 38 along the pipe section 31, the piston crown 44 has a central receiving opening 49, through which the pipe section 31 is guided coaxially to the longitudinal axis 100. The cylinder piston 38 can sealingly abut the pipe piece 31 in the radial direction, wherein for this purpose, for example, a sealing means, not shown, is arranged within the receiving opening 49. For example, the cylinder piston 38 and / or the cylinder housing 37 can be designed as a sheet metal shaped component.FIGS. 3 and 4 each show the oil cross member 21 according to FIG. 2 in an installation situation. FIG. 3 shows the mounting on the first housing part 22 a, wherein the oil cross member 21 is inserted into the oil feed opening 23 for this purpose via the connecting piece 33 aformed on the cylinder housing 37, as described in FIG. 2. As can be seen from FIG. 3, the oil cross member 21 is arranged radially between the drive shaft 10 and the output shafts 11 a, 11 b, wherein the first oil nozzle 25 ais directed into the engagement region of the first transmission stage 13 aand the second oil nozzle 25 bis directed into the engagement region of the second transmission stage 13 b. FIG. 4 illustrates the mounting of the oil cross member 21 on the second housing part 22 b, wherein the oil cross member 21 is inserted into the oil discharge opening 24 for this purpose via the connecting piece 33 bformed on the pipe piece 31, as described in FIG. 2. This creates a detachable plug connection, which allows particularly simple assembly of the two housing parts 22 a, 22 b. For example, the two housing parts 22 a, 22 bcan be plugged together via the oil cross-member 21 during assembly in the axial direction with respect to the axis of rotation 100 or the longitudinal axis 101. The oil cross-member 21 thus also serves for the mechanical connection or support of the two housing parts 22 a, 22 b.List of reference characters1 Drive train 2 electric machine 3 transmission 4 stator 5 rotor 6 machine housing 7 spur gear transmission 8 transfer gear 9 transmission housing 10 drive shaft 11 a,bdrive shafts 12 intermediate shaft 13 a,bgear stages 14 a- cdrive shaft bearings 15 a,bbetween shaft bearings 16 a,bdrive shaft bearings 17 oil supply system 18 oil sump 19 oil pump 20 oil flow path 21 oil cross member 22 a,b housing parts 23 oil supply opening 24 oil discharge opening 25 a,boil nozzles 26 a, 26 boil supply points 27 oil inlet 28 a,boil channels 29 a- coil outlets 30 a- cfurther oil supply points 31 pipe piece 32 through opening 33 a,bconnection piece 34 a,bsealing rings 35 pressure control valve 36 bypass flow path 37 cylinder housing 38 cylinder piston 39 bypass opening 40 return spring 41 cylinder cover 42 inlet opening 43 annular space 44 piston head 45 annular space step 46 guide step 47 annular channel 48 a- cpart flow paths 49 receiving opening 100 axis of rotation 101 longitudinal axis 102 closed position 103 release positionReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 123 189 A1

[0003]

Claims

Oil supply system (17) for an electric drive train (1) of a vehicle, - having an oil sump (18), - having an oil pump (19) for conveying an oil from the oil sump (19) along an oil flow path (20), - having two housing parts (22a, 22b) of a transmission (3) which are connected to one another in the axial direction with respect to a rotational axis (100) of a transmission shaft (10), wherein a first housing part (22a) has an oil feed opening (23) and a second housing part (22b) has an oil discharge opening (24), wherein the oil flow path (20) runs in sections through the transmission (3) from the oil feed opening (23) to the oil discharge opening (24), - an oil cross member (21) which fluidically connects the oil feed opening (23) and the oil discharge opening (24), which has at least one oil nozzle (25a, 25b) arranged between the oil feed opening (23) and the oil discharge opening (24) for the targeted oil feed to an oil supply point (26a, 26b) within the transmission (3), characterized bya pressure control valve (35) which is operatively connected to the oil traverse (21) and is arranged fluidically between the oil feed opening (23) and the at least one oil nozzle (26a, 26b), wherein the pressure control valve (35) is designed, when a specified oil pressure is exceeded, to open a bypass flow path (36) running parallel to the oil flow path (20), so that when the oil pressure is exceeded, an excess amount of oil is conducted past the oil supply points (26a, 26b) via the bypass flow path (36).Oil supply system (17) according to Claim 1, characterized in that the oil cross member (21) and the pressure regulating valve (35) form a common and / or self-holding structural unit.Oil supply system (17) according to Claim 1 or 2, characterized in that the pressure regulating valve (35) has a cylinder housing (37) fixed to the oil cross-member (21), a cylinder piston (38) which can be displaced within the cylinder housing (37) along the oil cross-member (21) between a closed position (102) and a release position (103), and a restoring spring (40) which applies a spring force to the cylinder piston (38) in the direction of the closed position (102), wherein the cylinder housing (37) has at least one bypass opening (39) which is closed in the closed position (102) and at least partially released in the release position (103).Oil supply system (17) according to Claim 3, characterized in that the oil cross member (21) has a straight pipe piece (31) which fluidically connects the oil feed opening (23) and the oil discharge opening (24) in the axial direction with respect to its longitudinal axis (101), wherein the cylinder housing (37) is fixed to the pipe piece (31) and the cylinder piston (38) is guided axially in a straight manner along the longitudinal axis (101).Oil supply system (17) according to Claim 4, characterized in that the pipe piece (31) is fixed between the two housing parts (22a, 22b), wherein the longitudinal axis (101) is arranged axially parallel and / or axially offset with respect to the axis of rotation (100).Oil supply system (17) according to one of Claims 3 to 5, characterized in that the cylinder housing (37) defines an inlet opening (42), wherein the oil cross member (21) is arranged within the inlet opening (42) to form an annular space (43), wherein the annular space (43) is axially delimited by a piston crown (44) of the cylinder piston (38).Oil supply system (17) according to Claim 6, characterized in that the cylinder piston (38) has an annular space stage (45) and a guide stage (46), wherein the cylinder piston (38) forms, with the annular space stage (45) within the annular space (43), an annular channel (47) which is axially delimited by the guide stage (46) and connects the oil feed opening (23) fluidically to the bypass opening (39) at least in the release position (103).Oil supply system (17) according to one of the preceding claims, characterized in that the cylinder housing (37) has, on the end side, a first connecting piece (33a), which is inserted in a sealing manner in the oil feed opening (23), and in that the oil cross member (21) has, on the end side, a second connecting piece (33b), which is inserted in a sealing manner in the oil discharge opening (24).Oil supply system (17) according to one of the preceding claims, characterized in that the oil flow path (20) downstream of the pressure regulating valve (35) is divided into a plurality of partial flow paths (48a, 48b, 48c).Electric drive train (1) having at least one electric machine (2), a transmission (3) and having the oil supply system (17) according to one of the preceding claims, wherein the oil supply system (17) is designed to supply the electric machine (2) and the transmission (3) with oil.

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