Drive system for a motor vehicle and method for operating such a drive system

Abstract

The invention relates to a drive unit (10) for a motor vehicle, comprising a hydraulic circuit (12) through which hydraulic fluid flows for actuating, cooling, and / or lubricating at least a part (T) of the drive unit (10). The hydraulic circuit includes a mechanical gear pump (14) that is mechanically coupled or connectable to a drive motor and is thereby driven by the drive motor and is designed to pump the hydraulic fluid. The gear pump has a first flow (16) and a second flow (18) through which the hydraulic fluid flows. An electric pump (20) is provided, the pumping element (22) of which is designed to pump the hydraulic fluid and is rotatable in a first direction of rotation for pumping the hydraulic fluid and in a second direction of rotation opposite to the first direction of rotation for pumping the hydraulic fluid.

Description

[0001] The invention relates to a drive device for a motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to a method for operating such a drive device.

[0002] DE 10 2015 120 440 A1 discloses a pump arrangement for a drive train of a motor vehicle as known, which has a first pump and a second pump.

[0003] CN 107 939 786 A describes a hydraulic oil supply system for a dual-clutch automatic transmission and a motor vehicle, which has a high-pressure circuit and a low-pressure circuit with a high-pressure pump and a low-pressure pump.

[0004] DE 10 2018 214 438 A1 discloses a hydraulic system for a transmission of a motor vehicle powertrain as known, wherein the hydraulic system has a pressure supply unit with two output lines for supplying a pressure circuit.

[0005] The CN 109 027 207 A describes a hydraulic oil supply system for an automatic transmission, which has three oil channels that are fed by a mechanical low-pressure pump, a mechanical high-pressure pump and an electronic pump.

[0006] The DE 10 2020 122 260 A1 is a pump unit with a dual pump as is known.

[0007] CN 116 104 929 A discloses a special hydraulic transmission system for increasing the range in the area of ​​automotive structural components with a two-stage oil pump structure with variable displacement.

[0008] DE 10 2011 100 801 A1 discloses a clutch transmission for a motor vehicle as a known invention, with a hydraulic circuit for actuating and / or cooling the clutch transmission. WO 2015 / 193170 A1 also discloses a pumping device for a motor vehicle.

[0009] The object of the present invention is to provide a drive device for a motor vehicle and a method for operating such a drive device, so that a particularly advantageous fluid supply can be realized.

[0010] This problem is solved by a drive device with the features of claim 1 and by a method with the features of claim 6. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0011] A first aspect of the invention relates to a drive device for a motor vehicle, also referred to simply as a vehicle, preferably a motor car, in particular a passenger car. This means that the motor vehicle, in its fully manufactured state, has the drive device and can be driven by means of the drive device. The drive device has a hydraulic circuit, also referred to simply as a circuit or circuit or hydraulic circuit, through which a hydraulic fluid can flow. The hydraulic fluid is also referred to simply as a fluid and can, for example, be an oil, so that the hydraulic circuit can, for example, be an oil circuit. By means of the hydraulic fluid, which is, for example, oil, at least a part of the drive device can be actuated and / or cooled and / or lubricated.The actuation of at least part of the drive unit can be understood as follows: The part of the drive unit is or includes, for example, at least one actuating element that can be actuated by means of hydraulic fluid. The actuating element is, for example, a switching element, which may be part of a clutch or brake. By actuating the actuating element, the clutch or brake can, for example, be engaged and / or disengaged.

[0012] The hydraulic circuit includes a mechanical gear pump, also referred to as the first pump. The first pump is mechanically coupled to, or can be coupled to, a drive motor and is thus driven by the drive motor. In particular, the drive unit can include the drive motor. More specifically, the motor vehicle can be driven by means of the drive motor. For example, the drive motor is an internal combustion engine, also known as a combustion engine or internal combustion power unit. By driving the gear pump (first pump), the hydraulic fluid can be pumped, in particular, pumped through the hydraulic circuit. Thus, the gear pump (first pump) is designed for pumping the hydraulic fluid. The first pump has a first flow and a second flow through which the hydraulic fluid can flow.In particular, the waters of the gear pump are connected in parallel to each other in terms of flow technology.

[0013] The hydraulic circuit also includes an electric pump, which is also referred to as a second pump. Especially when the hydraulic fluid is oil, the electric pump is also called an electric oil pump. The electric pump has a pumping element for conveying the hydraulic fluid. The pumping element of the electric pump can be rotated either in a first direction of rotation for conveying the hydraulic fluid or in a second direction of rotation opposite to the first direction of rotation for conveying the hydraulic fluid. For example, the second pump has a pump housing in which the pumping element is arranged, in particular such that the pumping element can be rotated about an axis of rotation either in the first direction of rotation or in the second direction of rotation relative to the pump housing.The hydraulic fluid is conveyed by rotating the conveying element around its axis of rotation relative to the pump housing in the first direction of rotation. The hydraulic fluid is conveyed by rotating the conveying element around its axis of rotation relative to the pump housing in the second direction of rotation. For example, rotating the conveying element in the first direction of rotation conveys the hydraulic fluid through the pump housing in a first flow direction. Rotating the conveying element in the second direction of rotation conveys the hydraulic fluid through the pump housing in a second flow direction, opposite to the first.For example, the electric pump has a motor, in particular designed as an electric motor, by means of which the conveying element can be driven and thereby selectively rotated in the first direction of rotation or in the second direction of rotation relative to the pump housing.

[0014] The hydraulic circuit has a first pressure line assigned to the second pump, which can be pressurized with hydraulic fluid delivered by the pumping element by rotating the pumping element in the first direction. The hydraulic circuit also has a second pressure line assigned to the second pump, which can be pressurized with hydraulic fluid delivered by the pumping element by rotating the pumping element in the second direction. This means that by rotating the pumping element in the first direction, the hydraulic fluid can be pumped through the first pressure line. By rotating the pumping element in the second direction, the hydraulic fluid can be pumped through the second pressure line.

[0015] In order to transport the hydraulic fluid particularly advantageously, and especially particularly efficiently, and thus to supply at least part of the drive unit with the hydraulic fluid particularly advantageously, and especially particularly efficiently, and thereby actuate and / or cool and / or lubricate it, the invention provides that the hydraulic circuit has a working pressure supply line which can be fed, i.e., supplied, with hydraulic fluid from the first flow. The hydraulic circuit also has a lubrication pressure supply line, which is provided in addition to the working pressure supply line. Either the lubrication pressure supply line or the working pressure supply line can be fed, i.e., supplied, with hydraulic fluid from the second flow.For this purpose, a hydraulic switching valve is arranged in the second flow, which can be switched to a switching position, also referred to as the first switching position, by means of a control pressure, in particular hydraulic fluid, branched off from the second pressure line. In this switching position, the second flow is fluidically, i.e., hydraulically, connected to the working pressure supply line, particularly via the switching valve. Specifically, the switching valve is adjustable, i.e., switchable, between the first switching position and a second switching position. When the term "switching position" is used before and after, it refers, unless otherwise specified, to the first switching position.In the first switching position, the second flow is fluidically connected to the working pressure supply line via the switching valve, particularly while a fluidic connection of the second flow to the lubrication pressure supply line via the switching valve is preferably omitted. In the second switching position, for example, the second flow is fluidically connected to the lubrication pressure supply line via the switching valve, particularly while a fluidic connection of the second flow to the working pressure supply line via the switching valve is omitted.Particularly during operation of the drive unit, the working pressure supply line is or is permeated by hydraulic fluid at a first pressure, i.e., at a first pressure level, and the lubrication pressure supply line is or is permeated by hydraulic fluid at a second pressure, i.e., at a second pressure level, wherein the first pressure or the first pressure level is greater than the second pressure or the second pressure level, in particular at least four times, and in particular at least five times, as great as the second pressure level. The first pressure is also referred to as the working pressure, and the second pressure is also referred to as the lubrication pressure.Due to the lower pressure level of the second pressure level in the lubrication supply line compared to the first, the operation of the mechanical transmission pump in stationary operation with fixed gears—which, in terms of time, represents a predominantly driving operation—is very efficient overall, resulting in a particularly advantageous hydraulic fluid supply. Furthermore, the electric pump can support the mechanical transmission pump, especially when high operating pressures are required, i.e., when high first pressure values ​​are necessary.

[0016] In an advantageous embodiment of the invention, the switching valve is switchable from the first switching position to the second switching position, in which the second flow is fluidically, i.e., hydraulically, connected to the lubrication pressure supply line, particularly via the switching valve. This ensures a demand-based and efficient supply of hydraulic fluid to at least part of the drive unit.

[0017] Another embodiment is characterized by the fact that a check valve is arranged in the first flow upstream of a connection point where, in the (first) switching position, the hydraulic fluid from the second flow can be introduced into the working pressure supply line. This check valve automatically blocks the flow of hydraulic fluid from the first flow, preventing any flow away from the connection point and, in particular, towards the mechanical gear pump. This allows unwanted flow of hydraulic fluid to be avoided in a particularly advantageous manner, thus enabling a highly efficient hydraulic fluid supply.

[0018] In a further, particularly advantageous embodiment of the invention, a reservoir is provided in which the hydraulic fluid is received or stored. A first suction line is associated with the electric pump, through which the hydraulic fluid can be drawn from the reservoir and thus conveyed by rotating the conveying element in the first direction. Furthermore, a second suction line is associated with the electric pump, through which the hydraulic fluid can be drawn from the reservoir and thus conveyed by rotating the conveying element in the second direction.To achieve a particularly efficient supply of hydraulic fluid, a first check valve is installed in the first suction line. This valve automatically blocks the flow of hydraulic fluid towards the reservoir. Furthermore, a second check valve is installed in the second suction line, which also automatically blocks the flow of hydraulic fluid towards the reservoir. This effectively prevents the electric pump from drawing in air, thus ensuring a particularly efficient supply of hydraulic fluid.

[0019] In order to supply at least part of the drive unit with hydraulic fluid in a particularly advantageous manner, a further embodiment of the invention provides that the drive unit has a filter common to the suction lines, through which hydraulic fluid can be drawn from the reservoir into the respective suction line by means of the conveying element.

[0020] A second aspect of the invention relates to a method for operating a drive device according to the first aspect of the invention. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0021] In order to supply at least part of the drive unit with hydraulic fluid in a particularly advantageous manner, the second aspect of the invention provides that the drive unit is operated in a first operating mode. In the first operating mode, the switching valve is in a second switching position, in which the second flow is fluidically connected, in particular via the switching valve, to the lubrication pressure supply line. In the second operating mode, the pumping element is rotated in the first direction of rotation, whereby hydraulic fluid is pumped into the lubrication pressure supply line by means of the pumping element.In the first operating mode, the hydraulic fluid from the first reservoir is pumped into the working pressure supply line by means of the mechanical gear pump, and in the first operating mode, the hydraulic fluid from the second reservoir is pumped into the lubrication pressure supply line via the switching valve by means of the mechanical gear pump. This results in a particularly advantageous hydraulic fluid supply.

[0022] A further embodiment of the invention is characterized in that the drive unit is operated in a second operating mode. In the second operating mode, the conveying element is rotated in the second direction of rotation, whereby the switching valve is supplied with hydraulic fluid and is thus in the first switching position, in which the second flow is fluidically, i.e., hydraulically, connected to the working pressure supply line, particularly via the switching valve. In the second operating state, the hydraulic fluid from the first flow is conveyed into the working pressure supply line by means of the mechanical gear pump, and in the second operating state, the hydraulic fluid from the second flow is conveyed into the working pressure supply line via the switching valve by means of the mechanical gear pump.This allows for a particularly advantageous and needs-based supply of hydraulic fluid.

[0023] In order to supply at least part of the drive unit with hydraulic fluid in a particularly demand-oriented and thus particularly advantageous, and especially particularly efficient, a further embodiment of the invention provides that the drive unit is operated in a third operating mode. In the third operating mode, the conveying element is rotated in the second direction of rotation, whereby the switching valve is supplied with hydraulic fluid and is thereby in the first switching position, in which the second flow is fluidically, i.e., hydraulically, connected to the working pressure supply line, particularly via the switching valve.In the third operating mode, the hydraulic fluid from the first reservoir is pumped into the working pressure supply line by means of the mechanical gear pump, and in the third operating mode, the hydraulic fluid from the second reservoir is pumped into the working pressure supply line via the switching valve by means of the mechanical gear pump. Additionally, in the third operating mode, the hydraulic fluid is pumped into the working pressure supply line by means of the pumping element. This allows for a particularly advantageous hydraulic fluid supply.

[0024] Finally, operating the drive unit in a fourth operating mode has proven particularly advantageous for achieving a highly efficient hydraulic fluid supply. In this mode, the pumping element rotates in the second direction, thereby supplying the hydraulic fluid to the valve and placing it in the first switching position. In this position, the second flow is fluidically, i.e., hydraulically, connected to the working pressure supply line, particularly via the valve. In this fourth operating mode, the hydraulic fluid is not pumped by the mechanical gear pump. Furthermore, in this mode, the pumping element delivers the hydraulic fluid to the working pressure supply line. This ensures a particularly efficient supply of hydraulic fluid to this part of the drive unit.

[0025] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0026] The drawing shows in: Fig. 1. Partial schematic representation of a drive unit of a motor vehicle in a first operating mode; Fig. 2. Partial schematic representation of the drive unit in a second operating mode; Fig. 3. A partial schematic representation of the drive unit in a third operating mode; and Fig. 4. Partially a schematic representation of the drive device in a fourth operating mode.

[0027] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0028] Fig. 1, Fig. 2, Fig. 3 to Fig. Figure 4 shows, in partial schematic representation, a drive unit 10 for a motor vehicle, also referred to simply as a vehicle. Fig. Figure 1 shows a first operating mode of the drive unit 10, wherein Fig. 2 shows a second operating mode of the drive unit 10. Fig. Figure 3 shows a third operating mode of the drive unit 10, and Fig. Figure 4 shows a fourth operating mode of the drive unit 10. The motor vehicle can be driven or is driven by means of the drive unit. In particular, the drive unit 10 has a drive engine (not shown in the figure) by means of which the motor vehicle can be driven or is driven. For example, the drive engine is an internal combustion engine, also known as a combustion engine, by means of which the motor vehicle can be driven or is driven. Furthermore, it is conceivable that the drive unit 10 has a transmission, provided in particular in addition to the drive engine, by means of which, for example, the motor vehicle can be driven by the drive engine. For example, the transmission is a hybrid transmission.Thus, for example, the drive unit 10 comprises at least or exactly one electric machine in addition to the drive motor and the transmission, by means of which, for example, the motor vehicle can be driven, in particular electrically and, most especially, purely electrically. The transmission can have several gears that differ, for example, in their gear ratios.

[0029] Out of Fig. Figure 1 shows that the drive unit 10 has a hydraulic circuit 12, which is also simply referred to as a circuit or circuit and is permeable to, or is permeated by, a hydraulic fluid. The hydraulic fluid is also simply referred to as a fluid or liquid and is preferably an oil. At least a part of the drive unit 10 can be actuated and / or cooled and / or lubricated by means of the hydraulic fluid. Actuating at least a part of the drive unit 10 means, for example, that at least one switching element of the drive unit 10, in particular of the transmission, can be actuated by means of the hydraulic fluid. By actuating the switching element, at least one or exactly one of the gears can be engaged and / or disengaged.

[0030] The hydraulic circuit 12 comprises a first pump 14, which is a mechanical gear pump. The first pump 14 is mechanically coupled or connectable to the drive machine, in particular purely mechanically, whereby the pump 14 can be driven by the drive machine, in particular mechanically and especially purely mechanically. By driving the pump 14, the hydraulic fluid is pumped or conveyed by means of the pump 14. The first pump 14 has a first flux 16 and a second flux 18 through which the hydraulic fluid flows. For example, the pump 14 can be mechanically coupled or connected to an output shaft of the drive machine and thus can be driven by the output shaft, in particular mechanically and especially purely mechanically.

[0031] The hydraulic circuit 12 also includes a second pump 20, in addition to the first pump 14, which is an electric pump. The second pump 20 has a pumping element 22 which, particularly relative to a pump housing of the pump 20, can be rotated about an axis of rotation either in a first direction of rotation or in a second direction of rotation opposite to the first. For this purpose, the second pump 20 has an electric motor 24, also referred to simply as a motor, by means of which the pumping element 22 of the pump 20 can be driven and thereby rotated either in the first direction of rotation or in the second direction of rotation. By rotating the pumping element 22 about the axis of rotation and relative to the pump housing, hydraulic fluid can be pumped or, in particular, pumped through the pump housing.In other words, the conveying element 22 can be rotated either in the first direction of rotation to convey the hydraulic fluid or in the second direction of rotation to convey the hydraulic fluid.

[0032] Hydraulic circuit 12 has a first pressure line 26 assigned to the second pump 20, through which the hydraulic fluid can flow. The first pressure line 26 can be pressurized with the hydraulic fluid conveyed by the pumping element 20 by rotating the pumping element 20 in the first direction of rotation. Hydraulic circuit 12 also has a second pressure line 28, through which the hydraulic fluid can flow. The second pressure line 28 can be pressurized with the hydraulic fluid conveyed by the pumping element 20 by rotating the pumping element 20 in the second direction of rotation. In other words, when the pumping element 22 is rotated in the first direction of rotation, the hydraulic fluid is thereby conveyed through the first pressure line 26 by the pumping element 22 and conveyed away from the pumping element 22 via the pressure line 26.If the conveying element 22 is rotated in the second direction of rotation, the hydraulic fluid is thereby conveyed through the second pressure line 28 by means of the conveying element 22 and thus conveyed away from the conveying element 22 via the pressure line 28.

[0033] To at least the in Fig. To supply the part of the drive unit 10 designated T with hydraulic fluid particularly efficiently, the hydraulic circuit 12 has a working pressure supply line 30, which can be fed, i.e., supplied, with hydraulic fluid from the first supply line 16. The hydraulic circuit 12 also has a lubrication pressure supply line 32, which will be explained in more detail below. The working pressure supply line 30 is also referred to as the first supply line, and the lubrication pressure supply line 32 is also referred to as the second supply line. Either the lubrication pressure supply line 32 or the working pressure supply line 30 can be fed, i.e., supplied, with hydraulic fluid from the second supply line 18. For this purpose, a hydraulic switching valve 34 is arranged in the second supply line 18, which is connected between a Fig. 2 shown first switching position S1 and one in Fig. The second switching position S2 shown in Figure 1 is switchable. The switching slide 34 can be switched from switching position S2 to switching position S1 by means of a control pressure branched off from the second pressure line 28 of the hydraulic fluid conveyed through the pressure line 28 by means of the conveying element 22, in which, as shown in Figure 1, the hydraulic fluid is conveyed through the pressure line 28 by means of the conveying element 22. Fig. As can be seen, the second flow 18 is hydraulically, i.e., fluidically, connected to the working pressure supply line 30 via the switching valve 34. In the first switching position S1, there is no fluidic connection between the flow 18 and the second supply line via the switching valve 34. In the second switching position S2, the second flow is fluidly, i.e., hydraulically, connected to the lubrication pressure supply line 32 via the switching valve 34, whereby in the second switching position S2 there is no fluidic connection between the flow 18 and the first supply line (working pressure supply line 30) via the switching valve 34. In particular, the switching valve 34 can be switched from switching position S1 to switching position S2 depending on the control pressure branched off from the second pressure line 28.For example, if the control pressure of the hydraulic fluid prevailing in the second pressure line 28, and in particular caused by the pumping element 22, exceeds a switching limit, the switching valve 34 is thereby switched from switching position S2 to switching position S1 and, in particular, held in switching position S1. If the control pressure is less than or equal to the switching limit, the switching valve 34 is subsequently, for example, spring-loaded and thus switched from switching position S1 to switching position S2, in particular switched back, by means of a spring element 37.

[0034] In Fig. 1 is designated by V as a connection point at which, in the first switching position S1, the hydraulic fluid from the second flow 18 can be introduced into the working pressure supply line 30 or is introduced. It can be seen that a first check valve 36 is arranged in the first flow 16 upstream of the connection point V, which automatically fluidically blocks the flow of hydraulic fluid from the first flow 16 away from the connection point V and, in particular, towards the pump 14.

[0035] The drive unit 10 has a reservoir 38, shown schematically in the figure, in which the hydraulic fluid is received or stored. A first suction line 40 is assigned to the second pump 20, through which the hydraulic fluid can be drawn from the reservoir 38 by rotating the pumping element 22 in the first direction of rotation and thus conveyed to the pumping element 22. Furthermore, a second suction line 42 is assigned to the second pump 20, through which the hydraulic fluid can be drawn from the reservoir 38 and thus conveyed to the pumping element 22 by rotating the pumping element 22 in the second direction of rotation.A check valve 44 is arranged in the first suction line 40, which automatically fluidically blocks the flow of hydraulic fluid from the first suction line 40 towards the reservoir 38 and away from the pumping element 22. A check valve 46 is also arranged in the second suction line 42, which automatically fluidically blocks the flow of hydraulic fluid from the second suction line 42 towards the reservoir 38 and away from the pumping element 22. A filter 48 common to suction lines 40 and 42 is also provided, through which the hydraulic fluid can be drawn from the reservoir 38 into the respective suction lines 40 and 42 by means of the pumping element 22. A second common filter 50 is assigned to the floods 16 and 18, through which the hydraulic fluid can be pumped from the reservoir 38 into the respective floods 16 and 18 by means of the pump 14.

[0036] Out of Fig. Figure 1 shows that in the first operating mode, the switching valve 34 is in the second switching position S2, in which the second flow 18 is fluidically connected to the lubrication pressure supply line 32 via the switching valve 34, while a fluidic connection between the flow 18 and the first supply line is omitted via the switching valve 34. In the first operating mode, the conveying element 22 is rotated in the first direction of rotation, whereby the hydraulic fluid is conveyed into the lubrication pressure supply line 32 by means of the conveying element 22 and thus by means of the pump 20. By means of the mechanical gear pump (pump 14), the hydraulic fluid from the first flow 16 is conveyed into the working pressure supply line 30, and by means of the mechanical gear pump (pump 14), hydraulic fluid from the second flow 18 is conveyed via the switching valve 34 into the lubrication pressure supply line 32. In the figures.Arrows illustrate the respective flow of the hydraulic fluid. In the first operating state, for example, the vehicle is driven, powered by the internal combustion engine and in steady gear. The first flow 16 supplies the first supply line with hydraulic fluid, and the second flow 18 supplies the second supply line with hydraulic fluid. The second pump 20, and thus the pumping element 22, supports the second supply line as needed, thus supplying the second supply line with hydraulic fluid. Control valves 52 and 54 are also shown schematically.Excess quantities of hydraulic fluid, especially from the first supply line, are regulated by means of the control valve 52, and excess quantities of hydraulic fluid, especially from the second supply line, are regulated by means of the control valve 54.

[0037] In the Fig. In the second operating mode shown in Figure 2, the conveying element 22 is rotated in the second direction of rotation, whereby the switching valve 34 is supplied with hydraulic fluid, particularly via the pressure line 28, and is thus in the first switching position S1, in which the second flow 18 is fluidically connected to the working pressure supply line 30 via the switching valve 34. This is evident from... Fig. Paragraph 2 states that in the second operating state, the hydraulic fluid from the first reservoir 16 is pumped into the working pressure supply line 30 by means of the mechanical transmission pump, i.e., pump 14. In the second operating state, the hydraulic fluid from the second reservoir 18 is pumped into the working pressure supply line 30 via the switching valve 34 by means of the mechanical transmission pump, i.e., pump 14. In the second operating state, for example, the vehicle, which is powered by the internal combustion engine, is driven, and gears are shifted. Both reservoir 16 and reservoir 18 supply the first supply line with hydraulic fluid. The pumping element 22 and the pump 20 pressurize the switching valve 34. The second supply line is supplied with an excess quantity of hydraulic fluid via the control valve 52.

[0038] In Fig. Figure 3 shows that in the third operating state, the pumping element 22 is rotated in the second direction of rotation, whereby the switching valve 34 is supplied with hydraulic fluid, particularly via the pressure line 28, and is thus in the first switching position S1, in which the second flow 18 is fluidically, i.e., hydraulically, connected to the working pressure supply line 30 via the switching valve 34. In the third operating state, the hydraulic fluid from the first flow 16 is pumped into the working pressure supply line 30 by means of the mechanical gear pump, i.e., by means of the pump 14, and in the third operating state, the hydraulic fluid from the second flow 18 is pumped into the working pressure supply line 30 via the switching valve 34 by means of the pump 14. Furthermore, in the third operating state, the hydraulic fluid is pumped into the working pressure supply line 30 by means of the pumping element 22.In the third operating state, the vehicle is driven by the internal combustion engine and a gearshift. Both the flood 16 and the flood 18 supply the first supply line with hydraulic fluid, with the pump 20 pressurizing the control valve 34 and supplying the first supply line with hydraulic fluid as needed. The second supply line is supplied with an excess quantity of hydraulic fluid via the control valve 52.

[0039] Out of Fig.Figure 4 shows that in the fourth operating mode, the pumping element 22 is rotated in the second direction, thereby supplying the hydraulic fluid to the switching valve 34, particularly via the pressure line 28, and thus placing it in the first switching position S1. In this position, the second flood 18 is fluidically, i.e., hydraulically, connected to the working pressure supply line 30 via the switching valve 34. In the fourth operating mode, the hydraulic fluid is not pumped by the pump 14. Furthermore, the hydraulic fluid is pumped into the working pressure supply line 30 by the pumping element 22. In this fourth operating state, for example, the vehicle is driven with the internal combustion engine switched off or in start-stop mode. The pump 14 is not running, so that the hydraulic fluid is not pumped through either flood 16 or flood 18.The conveying element 22 and the pump 20 press on the switching slide 34 and support the first supply line or its supply with hydraulic fluid as required, and if necessary the second supply line via the control slide 52, for example by an excess of volume flow in the first supply line. Reference symbol list 10 Drive unit 12 Hydraulic circuit 14 first pump 16 first flood 18 second flood 20 second pump 22 Conveyor element 24 Electric motor 26 first pressure line 28 second pressure line 30 Working pressure supply line 32 Lubrication pressure supply line 34 sound sliders 36 Check valve 37 Spring element 38 Reservoir 40 first suction line 42 second suction line 44 Check valve 46 Check valve 48 filters 50 filters 52 control slides 54 control slides S1 first switching position S2 second switching position V junction point T part

Claims

[1] Drive device (10) for a motor vehicle, comprising a hydraulic circuit (12) through which a hydraulic fluid flows for actuating, cooling and / or lubricating at least one part (T) of the drive device (10), which has: - a mechanical gear pump (14) mechanically coupled or capable of being coupled to a drive machine and thereby driven by the drive machine and designed to pump hydraulic fluid, which has a first flux (16) and a second flux (18) through which the hydraulic fluid can flow; - an electric pump (20) whose pumping element (22) is designed to pump the hydraulic fluid: ◯ rotatable in a first direction of rotation for conveying the hydraulic fluid; and o is rotatable in a second direction of rotation opposite to the first direction of rotation for conveying the hydraulic fluid; - a first pressure line (26) which can be pressurized with the hydraulic fluid conveyed by means of the conveying element (22) by rotating the conveying element (22) in the first direction of rotation; and - a second pressure line (28) which can be supplied with the hydraulic fluid conveyed by means of the conveying element (22) by rotating the conveying element (22) in the second direction of rotation characterized by , that: - the hydraulic circuit (12) has a working pressure supply line (30) which is to be supplied with the hydraulic fluid from the first flood (16); - the hydraulic circuit (12) has a lubrication pressure supply line (32); - optionally supplying either the lubrication pressure supply line (32) or the working pressure supply line (30) with the hydraulic fluid from the second flood (18); and - in the second flood (18) a hydraulic switching valve (34) is arranged, which can be switched into a switching position (S1) by means of a control pressure branched off from the second pressure line (28), in which the second flood (18) is fluidically connected to the working pressure supply line (30). [2] Drive device (10) according to claim 1, characterized by , that the switching slide (34) can be switched from the switching position (S1) as the first switching position (S1) to a second switching position (S2) in which the second flood (18) is fluidically connected to the lubrication pressure supply line (32). [3] Drive device (10) according to claim 1 or 2, characterized by, that in the first flood (16) upstream of a connection point (V), at which in the switching position (S1) the hydraulic fluid from the second flood (18) can be introduced into the working pressure supply line (30), a check valve (36) is arranged which automatically fluidically blocks the first flood (16) for a flow of hydraulic fluid away from the connection point (V). [4] Drive device (10) according to any of the preceding claims, characterized by , that: - a reservoir (38) is provided in which the hydraulic fluid can be received or stored; - a first suction line (40) is assigned to the electric pump (20), via which the hydraulic fluid can be drawn from the reservoir (38) by means of the pumping element (22) by rotating the pumping element (22) in the first direction of rotation; - a second suction line (42) is assigned to the electric pump (20), via which the hydraulic fluid can be drawn from the reservoir (38) by means of the pumping element (22) by rotating the pumping element (22) in the second direction of rotation; - a first check valve (44) is arranged in the first suction line (40), which automatically fluidically blocks the first suction line (40) from flowing hydraulic fluid towards the reservoir (38); and - a second check valve (46) is arranged in the second suction line (42), which automatically fluidically blocks the second suction line (42) for a flow of hydraulic fluid in the direction of the reservoir (38). [5] Drive device (10) according to claim 4, characterized bya filter (48) common to the suction lines (40, 42), through which the hydraulic fluid can be drawn from the reservoir (38) into the respective suction line (40, 42) by means of the conveying element (22). [6] Method for operating a drive device (10) according to any one of the preceding claims, characterized by , that the drive unit (10) is operated in a first operating mode in which: - the switching slide (34) is in a second switching position (S2) in which the second flood (18) is fluidically connected to the lubrication pressure supply line (32); - the conveying element (22) is rotated in the first direction of rotation, whereby the hydraulic fluid is conveyed into the lubrication pressure supply line (32) by means of the conveying element (22); - the hydraulic fluid is pumped from the first flood (16) into the working pressure supply line (30) by means of the mechanical gear pump (14); and - the hydraulic fluid from the second flood (18) is pumped into the lubrication pressure supply line (32) via the mechanical transmission pump (14) using the valve (34). [7] Method according to claim 6, characterized by , that the drive unit (10) is operated in a second operating mode in which: - the conveying element (22) is rotated in the second direction of rotation, whereby the switching slide (34) is supplied with hydraulic fluid and is therefore in the first switching position (S1), in which the second flood (18) is fluidically connected to the working pressure supply line (30); - the hydraulic fluid is pumped from the first flood (16) into the working pressure supply line (30) by means of the mechanical gear pump (14); and - the hydraulic fluid from the second flood (18) is pumped into the working pressure supply line (30) via the mechanical gear pump (14) using the switching valve (34). [8] Method according to claim 7, characterized by , that the drive unit (10) is operated in a third operating mode in which: - the conveying element (22) is rotated in the second direction of rotation, whereby the switching slide (34) is supplied with hydraulic fluid and is therefore in the first switching position (S1), in which the second flood (18) is fluidically connected to the working pressure supply line (30); - the hydraulic fluid is pumped from the first flood (16) into the working pressure supply line (30) by means of the mechanical gear pump (14); - the hydraulic fluid from the second flood (18) is pumped via the switching valve (34) into the working pressure supply line (30) by means of the mechanical gear pump (14); and - the hydraulic fluid is conveyed into the working pressure supply line (30) by means of the conveying element (22). [9] Method according to claim 8, characterized by , that the drive unit (10) is operated in a fourth operating mode in which: - the conveying element (22) is rotated in the second direction of rotation, whereby the switching slide (34) is supplied with hydraulic fluid and is therefore in the first switching position (S1), in which the second flood (18) is fluidically connected to the working pressure supply line (30); - the hydraulic fluid is not pumped by means of the mechanical gear pump (14); and - the hydraulic fluid is conveyed into the working pressure supply line (30) by means of the conveying element (22).

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