Cooling and lubricating system

Abstract

The invention relates to a cooling and lubricating system (13) comprising a pump unit (35), a collecting tank (20), and a dry sump (31), said pump unit (35) at least functionally having at least one bilge pump (33, 34) and a delivery pump (45). The at least one bilge pump (33, 34) is connected to the dry sump (31) on each suction side (37, 38) and to the collecting tank (20) on each pressure side (41, 42), whereas the delivery pump (45) is connected to a suction line (22) on the suction side (46), said suction line being connected to the collecting tank (20). A supply line (15) and a switch valve (49) which has a first working connection (54), a second working connection (53), and a third working connection (52) are provided. The first working connection (54) of the switch valve (49) is connected to the suction line (22), the second working connection (53) of the switch valve (49) is connected to the pressure side (47) of the delivery pump (45), and the third working connection (52) is connected to the supply line (15). In a first switch position of the switch valve (49), the second working connection (53) is connected to the first working connection (54) and is separated from the third working connection (52), whereas the second working connection (53) is connected to the third working connection (52) and is separated from the first working connection (54) in a second switch position of the switch valve (49).

Description

[0001] Cooling and lubrication system

[0002] The invention relates to a cooling and lubricating system for a motor vehicle drive axle, comprising a pump unit and a collection tank and a dry sump for liquid coolant and / or lubricant, wherein the pump unit at least functionally comprises at least one bilge pump and one feed pump and has a drive which is provided for jointly driving the at least one bilge pump and the first feed pump, wherein the at least one bilge pump is connected to the dry sump on one suction side and to the collection tank on one pressure side, whereas the feed pump is connected on one suction side to a suction line which is connected to the collection tank, and wherein a supply line is provided which can be fed with the coolant and / or lubricant from the collection tank.Furthermore, the invention relates to a motor vehicle drive axle with an aforementioned cooling and lubricating system and a method for operating a cooling and lubricating system.

[0003] In motor vehicles, supply systems are provided for the lubrication and / or cooling of certain components. These systems supply the associated components with coolant and / or lubricant, usually in the form of oil. Among other things, systems are known in which the coolant and / or lubricant, after being supplied to the associated components, is collected in one or more collection points, the so-called dry sump, from which the coolant and / or lubricant is subsequently pumped into a collection tank. The coolant and / or lubricant is then withdrawn from this collection tank to supply the components. A supply system with a dry sump has the advantage that such a system can also be implemented with low installation heights, which makes this system suitable for compact applications, such as motor vehicle drive axles.

[0004] DE 10 2019 201 863 B3 discloses a cooling and lubrication system with a dry sump and a collection tank, wherein a pump unit is also provided which consists of two bilge pumps in the form of a vane pump and a feed pump designed as a gerotor pump. The vane pump and the gerotor pump have a common drive, from which they can be driven by a common drive motor. The vane pump pumps coolant and lubricant in the form of oil from the dry sump into the collection tank, from which the gerotor pump can then suck in the oil and pump it into a supply line. The supply line leads to a component to be supplied in the form of an electrical machine. The vane pump is connected to the dry sump on each suction side, while one pressure side of the vane pump is connected to the collection tank.One suction side of the gerotor pump is connected to an intake line, which connects the suction side of the gerotor pump to a drain of the collection tank. On one pressure side, the gerotor pump is also connected to the supply line. The supply line branches off to the undervane grooves of the vane pump, where the undervane grooves supply the pump to another component in the form of a gearbox.

[0005] Based on the prior art described above, it is now the object of the present invention to provide a cooling and lubricating system with a pump unit which at least performs the function of at least one bilge pump and one feed pump and in which a common drive is provided, wherein in the cooling and lubricating system via the pump unit, on the one hand, a reliable filling of a collecting tank from a dry sump can be realized and, on the other hand, the most efficient supply in the cooling and lubricating system can be achieved.

[0006] This object is achieved starting from the preamble of claim 1 in conjunction with its characterizing features. The dependent claims following therefrom each provide advantageous developments of the invention. Furthermore, claim 10 relates to a motor vehicle drive axle with a cooling and lubricating system according to the invention, while claims 11 and 12 each relate to a method for operating a cooling and lubricating system. According to the invention, a cooling and lubricating system comprises a pump unit and a collection tank as well as a dry sump for liquid coolant and / or lubricant. The pump unit, at least functionally, has at least one bilge pump and one feed pump and has a drive which is provided for jointly driving the at least one bilge pump and the feed pump.Furthermore, the at least one bilge pump is connected to the dry sump on one suction side and to the collection tank on one pressure side, while the feed pump is connected to a suction line on one suction side, which is connected to the collection tank. A supply line is also provided, which can be fed with the coolant and / or lubricant from the collection tank.

[0007] The cooling and lubricating system according to the invention therefore provides a dry sump and a collection tank, the dry sump serving to collect the liquid coolant and / or lubricant after it has been supplied to one or more areas to be supplied. In this respect, the coolant and / or lubricant flows into the dry sump following the respective supply. The dry sump is preferably formed by one or more collection areas in which the coolant and / or lubricant collects after each outflow. In this case, the respective collection area is designed, in particular in the installed position, below a respective area to be supplied, so that the coolant and / or lubricant can flow into the respective collection area under the influence of gravity. The liquid coolant and / or lubricant is preferably oil.

[0008] For each supply of the one or more areas to be supplied, the coolant and / or lubricant is taken from a collection tank, which is filled from the dry sump during operation of the cooling and lubrication system and could also be referred to as a bunker. Accordingly, during operation of the cooling and lubrication system, the coolant and / or lubricant is taken from the collection tank for supplying the at least one area and supplied to the at least one area. Following the lubrication and / or cooling of the at least one area, the coolant and / or lubricant flows into the dry sump, from which it is then in turn recirculated into the collection tank. Within the scope of the invention, the collection tank can also be equipped with a temperature sensor, via which a temperature of the coolant and / or lubricant in the collection tank can be detected.

[0009] During operation of the cooling and lubrication system, the recirculation into the collection tank is carried out via at least one bilge pump, each of which is connected to the dry sump on one suction side and to the collection tank on one pressure side. During the recirculation process, the liquid coolant and / or cooling agent is defoamed by separating air. Preferably, a suction filter is provided on each suction side of the at least one bilge pump.

[0010] Preferably, the cooling and lubricating system is provided with a plurality of bilge pumps, particularly when the dry sump is composed of a plurality of collection areas. Furthermore, this can also be achieved in particular when the coolant and / or lubricant can collect in the dry sump in different ways depending on the operating state of a system comprising the cooling and lubricating system according to the invention. Thus, when the cooling and lubricating system is used in a motor vehicle, a locally greater accumulation of the coolant and / or lubricant in a collection area can occur in certain driving conditions of the motor vehicle, for example, when the motor vehicle corners or when driving up or down inclines.A locally greater accumulation of coolant and / or lubricant may then make it necessary for a sufficient return to the collection tank to be possible via one bilge pump alone, if there are several bilge pumps.

[0011] In the cooling and lubricating system according to the invention, a pump unit is provided which at least functionally comprises at least one bilge pump and one feed pump. In the context of the invention, “at least functional” means that the pump unit at least replicates the function of at least one bilge pump and / or the feed pump. Thus, the respective pump can physically be present as an individual pump of the pump unit, or the pump unit can have a common pump which implements the function of several individual pumps, i.e. one or more bilge pumps and / or the feed pump. If several bilge pumps are provided in the pump unit, these several bilge pumps are preferably formed by a common pump.

[0012] The feed pump of the pump unit is connected on one suction side to a suction line, which is connected to the collection tank. The feed pump of the pump unit can thus draw coolant and / or lubricant from the collection tank via the suction line. The suction line is connected, in particular, to an outlet of the collection tank. Alternatively or additionally, a suction filter is preferably also provided in the suction line.

[0013] For the purposes of the invention, a "line," such as the intake line or the supply line, is understood to mean a route for the lubricant and / or coolant between respective connection points. The respective line can be composed of several subsections. Furthermore, the respective line can be formed entirely by a conduit, entirely by a channel defined by a surrounding component, such as a housing, or in sections by one or more conduits and in sections by one or more channels.

[0014] The pump unit has a drive via which the at least one bilge pump and the feed pump in the pump unit are driven together. The joint drive of the at least one bilge pump and the feed pump means that the at least one bilge pump and the feed pump are peacefully coupled to one another and thus cannot be driven independently of one another. In this respect, a drive speed of the at least one bilge pump and a drive speed of the feed pump are subject to a fixed relationship to one another, with the at least one bilge pump and the feed pump particularly preferably having the same drive speed. The drive of the pump unit is in particular in the form of a drive shaft via which the at least one bilge pump and the feed pump, which are at least functionally provided, can be driven within the pump unit.Accordingly, the pumps, which are either present as individual pumps or combined into a respective common pump, are each drivingly connected to the drive shaft. Most preferably, the pump unit is assigned a drive motor, via which the joint drive of the at least one bilge pump and the feed pump of the pump unit can be achieved. This drive motor is particularly designed as an electric motor, so that the at least one bilge pump and the feed pump are electrically driven.

[0015] The supply line, which can be fed with the coolant and / or lubricant from the collection tank, is then preferably used to supply the area or areas to be supplied, wherein in the case of the preferred supply of several areas the supply line then branches off in particular into respectively assigned partial supply lines. By supplying the coolant and / or lubricant to the respective area, cooling or lubrication or both cooling and lubrication of the respective area is then carried out. The coolant and / or lubricant supplied in each case is then returned to the dry sump, although if necessary a direct return to the collection tank can also be carried out for at least one area to be supplied.In particular, a heat exchanger and / or a pressure filter and / or a temperature sensor can be provided in the supply line.

[0016] The cooling and lubrication system according to the invention is designed particularly for use in a motor vehicle drive axle, and preferably in an electrically driven motor vehicle drive axle. The supply line is then provided to supply the coolant and / or lubricant to different areas of the motor vehicle drive axle. These areas include, in particular, stator cooling of an electric drive motor of the motor vehicle drive axle, rotor cooling of the electric drive motor, one or more winding head showers of the electric drive motor, mechanical components such as a differential gear, bearings, etc.The pump unit of the cooling and lubrication system according to the invention then comprises, in particular, a plurality of bilge pumps to fill the collection tank from different collection areas forming the dry sump, and to ensure this filling even in all driving situations, such as prolonged cornering. Particularly preferably, the pump unit comprises, at least functionally, two bilge pumps.

[0017] The invention now comprises the technical teaching that a switching valve is provided which has a first working port, a second working port and a third working port and to which an actuating mechanism is assigned, via which the switching valve can be actively transferred between a first switching position and a second switching position. The first working port of the switching valve is connected to the intake line, the second working port of the switching valve is connected to a pressure side of the feed pump and the third working port is connected to the supply line. Furthermore, in the first switching position of the switching valve, the second working port is connected to the first working port and separated from the third working port, whereas in the second switching position of the switching valve the second working port is connected to the third working port and separated from the first working port.

[0018] In other words, the cooling and lubricating system according to the invention has a switching valve which is equipped with three working connections and in which two switching positions can be realized. This switching valve is connected to the intake line at the first working connection, while a connection is established to the pressure side of the feed pump at the second working connection and a connection to the supply line at the third working connection. In the first switching position, the valve is connected between the second working connection and the first working connection and thus between the pressure side of the feed pump and the intake line, while the third working connection and thus the supply line are separated from this.In contrast, in the second switching position, the second working port and the third working port are connected to each other, connecting the pressure side of the feed pump and the supply line via the switching valve. The first working port and thus the intake line are separated from this in the second switching position. A control actuator is also assigned to the switching valve to actively transfer the switching valve between the switching positions.

[0019] Such a design of a cooling and lubrication system has the advantage that, with the help of the switching valve and the associated actuating mechanism, reliable filling of the collection tank can be ensured via the at least one bilge pump of the pump unit, and at the same time, energy-efficient feeding of the supply line from the collection tank can be achieved via the feed pump of the pump unit. The drive of the pump unit can thus be designed in such a way that a sufficient volume flow from the dry sump to the collection tank to fill the collection tank is always achieved via the at least one bilge pump of the pump unit. At the same time, the feed pump of the pump unit can feed the supply line from the collection tank by connecting the second working connection with the third working connection on the switching valve.This supply can, however, be actively reduced or at least interrupted via the switching valve and the associated actuating mechanism by transferring the switching valve towards the first switching position or into the first switching position. This prevents an impending oversupply of the supply line via the feed pump of the pump unit, with the transfer of the switching valve towards the first switching position or into the first switching position resulting in at least partial pumping of the coolant and / or lubricant from the intake line back into the intake line. In the first switching position of the switching valve, virtually loss-free operation of the feed pump of the pump unit is enabled.Overall, the cooling and lubrication system thus creates the possibility of reliably filling the collection tank from the dry sump and efficiently feeding the supply line, despite the common drive of at least one bilge pump and the feed pump of the pump unit.

[0020] The switching valve is preferably designed as a directional control valve in which a valve piston is displaceably received in a valve housing. In particular, three valve pockets are designed in the valve housing, of which the valve pocket located in the middle is connected to the second working connection, while the valve pockets located on either side are each connected to one of the remaining working connections. In the first switching position, the valve piston is then moved in the valve housing into a position in which the valve pocket located in the middle is spatially connected to the valve pocket connected to the first working connection and is separated from the valve pocket connected to the third working connection via the valve piston.In contrast, in the second switching position of the switching valve, a position of the valve piston in the valve housing is brought about in which the valve piston separates the valve pocket located in the middle from the valve pocket connected to the first working connection and at the same time spatially connects it to the valve pocket connected to the third working connection.

[0021] In the sense of the invention, “actively transferable” means that the switching valve can be freely switched via the associated actuating mechanism in accordance with external specifications, i.e. it is not, for example, pressure-controlled.

[0022] According to one embodiment of the invention, only the two switching positions of the switching valve can be switched alternately. The switching valve can therefore only switch between the two switching positions, so that the second working port of the switching valve is connected either to the first working port by switching the first switching position or to the third working port by switching the second switching position. This allows for a simple design of the switching valve as a 3 / 2-way valve.

[0023] The cooling and lubrication system designed in this way can be operated in such a way that a drive speed at which the drive of the pump unit is driven is set according to a target speed at which a required volume flow of lubricant and / or coolant is pumped from the dry sump into the collection tank via the at least one bilge pump. If, at the drive speed and in the second switching position of the switching valve, a potential volume flow pumped into the supply line via the feed pump would exceed a target volume flow to be represented, an actual volume flow of the feed pump is set according to the target volume flow by switching back and forth between the first switching position and the second switching position of the switching valve. This has the advantage that an oversupply of the supply line by the feed pump of the pump unit can be prevented.In particular, a pulse-width modulated control of the actuating mechanism is carried out, whereby this is preferably carried out via a control unit which accesses the actuating mechanism accordingly.

[0024] According to an alternative design option, the switching valve can be continuously switched between the two switching positions, each of which provides a transition between the two switching positions. In this case, the switching valve is designed as a proportional valve, which allows the pump unit's feed pump to partially feed the fluid into the supply line and partially feed the fluid back into the intake line in each intermediate position. This allows the volume flow pumped into the supply line via the feed pump to be adjusted by selecting the respective intermediate position.

[0025] Preferably, the cooling and lubrication system can be operated in such a way that a drive speed at which the drive of the pump unit is driven is set according to a target speed at which a required volume flow of lubricant and / or coolant is pumped from the dry sump into the collection tank via the at least one bilge pump. If, at the drive speed and in the second switching position of the switching valve, a potential volume flow pumped into the supply line via the feed pump would exceed a target volume flow to be represented, an actual volume flow of the feed pump is set according to the target volume flow by setting an intermediate position of the switching valve associated with the target volume flow. In particular, the operation of the cooling and lubrication system is controlled via a control unit.

[0026] In a further development of the invention, the switching valve is preloaded in one of the two switching positions and can be moved towards the other switching position by the actuating actuator, counter to the preload. The switching valve is preferably preloaded in the first switching position and can be actively moved towards the second switching position by the actuating actuator, thereby enabling improved cold-start capability of the pump unit. In this case, transitions between the first working connection and the second working connection in the switching valve should be designed with as little resistance as possible. This is also advantageous if the supply line is only to be fed via the feed pump of the pump unit for short periods of time, for example because the supply line is essentially fed via a separate feed pump.

[0027] Alternatively, the switching valve can also be preloaded into the second switching position, while the actuator can actively transfer it to the first switching position. This is particularly useful when the feed pump of the pump unit is required to supply the supply line over extended periods.

[0028] In a further embodiment of the invention, the actuating mechanism is electromagnetic. This allows for reliable active actuation of the switching valve, with actuation preferably taking place via an electromagnetic pilot stage.

[0029] According to one possible embodiment of the invention, the switching valve is integrated into a housing of the pump unit. This enables a particularly compact arrangement of the switching valve on the pump unit.

[0030] According to an advantageous embodiment, a further feed pump is provided, to which a drive separate from the drive of the pump unit is assigned, wherein the further feed pump is connected to the intake line on a suction side and to the supply line on a pressure side. This further feed pump can therefore be used to feed the supply line independently of the pump unit. Particularly preferably, this further feed pump is a main feed pump of the cooling and lubrication system, via which the supply line and thus the supply to the area or areas to be supplied is largely fed, while the feed pump of the pump unit is only provided to compensate for this undersupply if the supply to the supply line via the main feed pump is too low.In particular, the further feed pump is mechanically driven, and when using the cooling and lubricating system according to the invention with an electrically driven motor vehicle drive axle, it is preferably coupled to a rotor of an electric machine of the motor vehicle drive axle.

[0031] A further embodiment of the invention is that the pump unit at least functionally comprises a first bilge pump and a second bilge pump, each of which is connected to the dry sump on a suction side and to the collection tank on a pressure side. This has the advantage that the collection tank can be filled from different collection areas of the dry sump. In a further development of this embodiment, the first bilge pump and the second bilge pump in the pump unit are then formed by one pump, in particular a double-stroke vane pump.

[0032] The invention also relates to a motor vehicle drive axle, which is in particular an electrically driven motor vehicle drive axle. This motor vehicle drive axle comprises a cooling and lubrication system according to one or more of the variants described above. Particularly preferably, this cooling and lubrication system has the additional feed pump, which is drivingly coupled to a rotor of an electric motor of the electrically driven motor vehicle drive axle. Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. It shows:

[0033] Fig. 1 is a schematic view of a motor vehicle with an electrically driven motor vehicle drive axle according to a preferred embodiment of the invention;

[0034] Fig. 2 is a schematic representation of a cooling and lubricating system of the motor vehicle drive axle from Fig. 1, according to a first embodiment of the invention; and

[0035] Fig. 3 is a schematic view of a cooling and lubricating system of the motor vehicle drive axle from Fig. 1, according to a second embodiment of the invention.

[0036] Fig. 1 shows a schematic view of a motor vehicle 1, in whose motor vehicle drive train 2 two motor vehicle drive axles 3 and 4 are provided. While the motor vehicle drive axle 3 is designed as a steerable front axle of the motor vehicle 1, the motor vehicle drive axle 4 is an unsteered rear axle. A drive motor 5 is assigned to the motor vehicle drive axle 3, which can be an internal combustion engine or an electric motor and which can be or is coupled to drive wheels of the motor vehicle drive axle 3 via a transverse differential (not shown here).

[0037] The motor vehicle drive axle 4 is also provided with a drive motor in the form of an electric machine 6, which is composed of a stator 7 and a rotor 8. The rotor 8 is connected to a rotor shaft 9, which is coupled to an input side of a downstream transverse differential 10. Via the transverse differential 10, a drive movement introduced into the transverse differential 10 is distributed to drive wheels 11 and 12 of the motor vehicle drive axle 4 in a manner known in principle to those skilled in the art. The motor vehicle drive axle 4 is equipped with a cooling and lubricating system 13, which is shown schematically in Fig. 2 and is designed according to a first embodiment of the invention. Within the cooling and lubricating system 13, various areas are supplied with a liquid coolant and lubricant, wherein the areas are each shown as replacement orifices 14 in Fig. 2.In addition to areas assigned to the electric machine 6, such as stator cooling, rotor cooling and one or more winding head showers, the coolant and lubricant is also supplied to mechanical components of the motor vehicle drive axle 4, wherein the mechanical components can be bearing points, tooth meshes of the transverse differential 10, seals, a parking lock, etc.

[0038] The liquid coolant and lubricant, which is oil, is supplied to the areas represented by the replacement orifices 14 via a supply line 15, which can branch into sub-supply lines 16 for this purpose. Within the supply line 15, the oil is first passed through a heat exchanger 17 and then through a pressure filter 18 before being supplied to the areas. Furthermore, a temperature sensor 19 is provided in the supply line 15, via which the temperature of the oil in the supply line 15 can be detected.

[0039] The supply line 15 is fed from a collection tank 20, which is connected to a suction line 22 at an outlet 21. A suction filter 23 is also provided in the suction line 22, through which the oil is guided as it is discharged from the collection tank 20. Furthermore, the collection tank 20 also has a temperature sensor 24, which can be used to determine the temperature of the oil in the collection tank 20.

[0040] The cooling and lubricating system 13 includes a feed pump 25 that is mechanically driven by the electric motor 6 of the motor vehicle drive axle 4, with the feed pump 25 being drivingly coupled to the rotor shaft 9 of the electric motor 6. Accordingly, a drive speed of the feed pump 25 depends on a speed of the rotor 8 of the electric motor 6 and thus also on a drive speed of the motor vehicle drive axle 4. The feed pump 25 is connected to the intake line 22 on a suction side 26, while a connection to the supply line 15 is established on a pressure side 27 of the feed pump 25. Furthermore, a reversing valve 28 is arranged between the pressure side 27 and the supply line 15. This reversing valve acts as a check valve to prevent oil from being sucked in from the supply line 15 via the feed pump 25 when the motor vehicle 1 is reversing, thus preventing the rotor shaft 9 from rotating in reverse.Another reversing valve 29 is arranged parallel to the feed pump 25. Also parallel to the feed pump 25 and the reversing valve 29 is a saturation valve 30, through which, once a defined pressure is reached on the pressure side 27 of the feed pump 25, oil can be returned to the suction side 26 of the feed pump 25 in the sense of suction charging.

[0041] The collection tank 20 is essentially filled with oil from a dry sump 31, into which the supplied oil flows after being fed to the areas formed by the replacement orifices 14. From one of the areas, however, a direct return to the collection tank 20 can also be realized via a connecting line 32. The collection tank 20 is filled from the dry sump 31 via two bilge pumps 33 and 34 of a pump unit 35, wherein the bilge pumps 33 and 34 within the pump unit 35 are formed by a double-stroke vane pump 36. Each of the bilge pumps 33 and 34 is connected to the dry sump 31 on a respective suction side 37 or 38 via an intermediate suction filter 39 or 40, whereas a connection to an inlet line 43 of the collecting tank 20 is established on a respective pressure side 41 or 42 of the respective bilge pump 33 or 34.

[0042] As can be seen in Fig. 2, the pump unit 35 also has a drive motor 44 in the form of an electric motor, which drives not only the vane pump 36 but also a feed pump 45. Due to this shared drive, the vane pump 36 and the feed pump 45 always have the same drive speed. The feed pump 45 is connected to the intake line 22 on a suction side 46, while a line 48 is connected to a pressure side 47 of the feed pump 45.

[0043] In addition to the drive motor 44, the vane pump 36 and the feed pump 45, a switching valve 49 is also integrated into a housing 50 of the pump unit 35, wherein the switching valve 49 is designed as a directional control valve. The switching valve 49 has a valve piston 51 which is slidably guided in a valve housing, wherein the valve housing in this case is preferably formed by the housing 50. Furthermore, the switching valve 49 has a plurality of working ports 52, 53 and 54, each of which establishes a connection to a valve pocket 55, 56 or 57 of the switching valve 49. The valve piston 51 is preloaded by a spring element 58 into a position which represents a first switching position of the switching valve 49. In this first switching position, the valve pocket 56 is spatially connected to the valve pocket 57, so that a connection is also established between the working port 53 and the working port 54.On the other hand, the valve piston 51, due to its position, ensures a spatial separation of the valve pocket 55 and thus also of the working connection 52 from the valve pocket 56 and the valve pocket 57 as well as the working connections 53 and 54.

[0044] The switching valve 49 is assigned an actuating actuator 59 which is electromagnetic and via which the valve piston 51 can be moved against the spring element 58 in the direction of an opposite position, which represents a second switching position of the switching valve 49. In this second switching position, the valve pocket 56 is then spatially connected to the valve pocket 55, thus establishing a connection between the working ports 53 and 52, while the valve pocket 57 and thus the working port 54 are separated therefrom. The switching valve 49 is preferably designed as a 3 / 2-way valve, in which switching can only take place between the two switching positions. However, the switching valve 49 could equally well be designed as a proportional valve, in which intermediate positions can be continuously adjusted between the two switching positions.While the working port 52 is connected to the supply line 15, a connection is established at the working port 53 to the line 48 and a connection is established at the working port 54 to the suction line 22. Thus, in the first switching position of the switching valve 49, when the feed pump 45 is driven, oil is sucked in from the suction line 43 via the feed pump 45 and pumped back into it, whereby this occurs essentially without loss. If, however, the second switching position of the switching valve 49 is set, oil is sucked in from the suction line 43 via the feed pump 45 and pumped into the supply line 15, whereby the supply line 15 can be fed alternatively to the feed pump 25 or in addition thereto.

[0045] The cooling and lubrication system 13 can be operated in such a way that a drive speed represented by the drive motor 44 is selected such that sufficient filling of the collecting tank 20 is always achieved using one of the two bilge pumps 33 and 34 alone. The extent to which the feed pump 45 also feeds the supply line 15 at this drive speed is adjusted via the switching valve 49. If the supply line 15 is insufficiently filled via the feed pump 25, a connection is established between line 48 and the supply line 15 via the switching valve 49, thus providing additional supply to the supply line 15 via the feed pump 45.If, in the course of this, it is achieved that an actual volume flow to be achieved corresponds to a target volume flow to be displayed in the supply line 15, for example because a delivery quantity via the feed pump 25 increases due to an increasing speed of the electric machine 6, a connection between the line 48 and the suction line 22 is established via the switching valve 49.

[0046] If the switching valve 49 is designed as a proportional valve, the actual volume flow can be adjusted by selecting the intermediate position assigned to the desired volume flow to be displayed. If, on the other hand, the switching valve 49 is designed as a 3 / 2-way valve, switching takes place between the two switching positions in order to either feed the supply line 15 via the feed pump 45 or to feed in a circuit via the feed pump 45. This switching is preferably carried out using pulse width modulation. Finally, Fig. 3 shows a schematic representation of a cooling and lubricating system 60 according to a second possible embodiment of the invention, which can be used as an alternative to the variant from Fig. 2 for the motor vehicle drive axle 4 in Fig. 1. The cooling and lubricating system 60 largely corresponds to the previous variant according to Fig.2, with the only difference that the working port 52 of the switching valve 49 is now connected to the intake line 22 and the working port 54 is now connected to the supply line 15. Accordingly, the valve piston 51 of the switching valve 49 is now biased into the second switching position of the switching valve 49, in which a connection is established between the line 48 and the supply line 15. Otherwise, the design option according to Fig. 3 corresponds to the variant according to Fig. 2, so that reference is made to the description in this regard.

[0047] By means of the inventive designs of a cooling and lubricating system, a reliable filling of a collecting tank and an energy-efficient supply of a supply line can be realized.

[0048] Reference symbol

[0049] Motor vehicle Motor vehicle drive train Motor vehicle drive axle Motor vehicle drive axle Drive machine Electric machine Stator Rotor

[0050] rotor shaft

[0051] Transverse differential drive wheel drive wheel

[0052] Cooling and lubrication system replacement panels

[0053] Supply line Partial supply lines Heat exchanger Pressure filter

[0054] Temperature sensor collection tank

[0055] Drain suction line suction filter temperature sensor feed pump

[0056] Suction side Pressure side Reversing valve Reversing valve Saturation valve Dry sump Connecting line Bilge pump Bilge pump Pump unit Vane pump Suction side Suction side Suction filter Suction filter Pressure side Pressure side Inlet line Drive motor Feed pump Suction side Pressure side Line Switching valve Housing Valve piston Working connection Working connection Working connection Valve pocket Valve pocket Valve pocket Spring element Actuating actuator

[0057] Cooling and lubrication system

Claims

Patent claims 1. Cooling and lubricating system (13; 60) for a motor vehicle drive axle (4), comprising a pump unit (35) and a collecting tank (20) as well as a dry sump (31) for liquid coolant and / or lubricant, wherein the pump unit (35) at least functionally comprises at least one bilge pump (33, 34) and one feed pump (45) and has a drive which is provided for jointly driving the at least one bilge pump (33, 34) and the feed pump (45), wherein the at least one bilge pump (33, 34) is connected on a suction side (37, 38) to the dry sump (31) and on a pressure side (41, 42) to the collecting tank (20), whereas the feed pump (45) is connected on a suction side (46) to a suction line (22) which is connected to the collecting tank (20), and wherein a supply line (15) is provided, which can be fed with the coolant and / or lubricant from the collecting tank (20), characterized in thatthat a switching valve (49) is provided which has a first working connection (54; 52), a second working connection (53) and a third working connection (52; 54) and to which a control actuator (59) is assigned, via which the switching valve (49) can be actively transferred between a first switching position and a second switching position, that the first working connection (54; 52) of the switching valve (49) is connected to the intake line (22), the second working connection (53) of the switching valve (49) is connected to a pressure side (47) of the feed pump (45) and the third working connection (52; 54) is connected to the supply line (15), and that in the switching valve (49) in the first switching position, the second working connection (53) is connected to the first working connection (54; 52) and is separated from the third working connection (52; 54),whereas the second working port (53) is connected to the third working port (52; 54) and separated from the first working port (54; 52) in the second switching position of the switching valve (49).

2. Cooling and lubricating system (13; 60) according to claim 1, characterized in that in the switching valve (49) only the two switching positions can be switched alternately.

3. Cooling and lubricating system (13; 60) according to claim 1, characterized in that in the switching valve (49) in addition to the two switching positions, intermediate positions are continuously variable, in which a transition between the two switching positions is realized.

4. Cooling and lubricating system (13; 60) according to one of claims 1 to 3, characterized in that the switching valve (49) is prestressed into one of the two switching positions and can be transferred counter to the prestress via the actuating actuator (59) in the direction of the other switching position.

5. Cooling and lubricating system (13; 60) according to one of the preceding claims, characterized in that the actuating mechanism (59) is designed electromagnetically.

6. Cooling and lubricating system (13; 60) according to one of the preceding claims, characterized in that the switching valve (49) is integrated into a housing (50) of the pump unit (35).

7. Cooling and lubricating system (13; 60) according to one of the preceding claims, characterized in that a further feed pump (25) is provided, to which a separate drive is assigned to the drive of the pump unit (35), wherein the further feed pump (25) is connected on a suction side (26) to the suction line (22) and on a pressure side (27) to the supply line (15).

8. Cooling and lubricating system (13; 60) according to one of the preceding claims, characterized in that the pump unit (35) at least functionally comprises a first bilge pump (33) and a second bilge pump (34), which are each connected on a suction side (37, 38) to the dry sump (31) and on a pressure side (41, 42) to the collecting tank (20).

9. Cooling and lubricating system (13; 60) according to claim 8, characterized in that the first bilge pump (33) and the second bilge pump (34) in the pump unit (35) are formed by a pump, in particular a double-stroke vane pump (36).

10. Motor vehicle drive axle (4), in particular electrically driven motor vehicle drive axle (4), comprising a cooling and lubricating system (13; 60) according to one or more of claims 1 to 9.

11. Method for operating a cooling and lubricating system (13; 60) according to claim 2, characterized in that a drive speed at which the drive of the pump unit (35) is driven is set according to a target speed at which a required volume flow of lubricant and / or coolant is conveyed from the dry sump (31) into the collecting tank (20) via the at least one bilge pump (33, 34), wherein if, at the drive speed and in the second switching position of the switching valve (49), a potential volume flow conveyed via the feed pump (45) into the supply line (15) would exceed a target volume flow to be represented, an actual volume flow of the feed pump (45) is set according to the target volume flow by switching back and forth between the first switching position and the second switching position of the switching valve (49).

12. Method for operating a cooling and lubricating system (13; 60) according to claim 3, characterized in that a drive speed with which the drive of the pump unit (35) is driven is set according to a target speed at which a required volume flow of lubricant and / or coolant is conveyed from the dry sump (31) into the collecting tank (20) via the at least one bilge pump (33, 34), wherein if, at the drive speed and in the second switching position of the switching valve (49), a potential volume flow conveyed via the feed pump (45) into the supply line (15) would exceed a target volume flow to be represented, an actual volume flow of the feed pump (45) is set according to the target volume flow by setting an intermediate position of the switching valve (49) associated with the target volume flow.

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