Drive device for a motor vehicle

Abstract

The invention relates to a drive device (100) for a motor vehicle (105), the drive device comprising: a machine housing section (300) having an electric machine (115); a gearbox housing section (305) having a gearbox (130); and a hydraulic system (135) for cooling and / or lubricating thermal and / or mechanical consumers in the machine housing section (300) and in the gearbox housing section (305). The hydraulic system (135) comprises a pump system (200, 600) having a first pump (601). The machine housing section (300) has a first suction point (310) which is hydraulically connected to the first pump (601) by a first suction line (225), and the gearbox housing section (305) has a second suction point (400) which is hydraulically connected to the first pump (201) by a second suction line (230). The first pump (601) is in the form of a gear pump which comprises more than two externally toothed pump gears (611, 612, 613).

Description

[0001] ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07

[0002] Drive unit for a motor vehicle

[0003] The present invention relates to a drive unit for a motor vehicle comprising a dry-sump hydraulic system for cooling and lubricating mechanical and / or electrical components, and an electric drive axle. The present invention also relates to a motor vehicle with such a drive unit.

[0004] From the unpublished German patent application DE 102023212588.9 of the applicant, a drive device comprising an electric machine and a gearbox is known, the components of which are at least partially arranged in a common housing or interconnected sub-housings. A liquid operating medium is stored in the interconnected sub-housings or in a common housing for cooling and lubricating the mechanical and electrical components. The fact that the operating medium is stored in both sub-housings and can flow back and forth between them via the connection between the two sub-housings is hereinafter also referred to as a hydraulic connection between the sub-housings. In general, a hydraulic connection between several components is understood to mean that the operating medium can flow from one component to another through this connection.The liquid operating medium is usually a hydraulic fluid such as gear oil, hereinafter also referred to simply as oil.

[0005] The operating fluid is transported to the points requiring cooling and lubrication by a lubricating / cooling oil pump, hereinafter referred to as a pressure pump. After dripping from the components requiring lubrication and cooling, which represent the consumers of the hydraulic system, the oil collects in a section of the housing. From this area, it is extracted by at least one pump and conveyed to a reservoir. This principle is also known as dry sump lubrication, and the extraction pump is hereinafter referred to as a dry sump or extraction pump. The pressure pump supplies the oil from the reservoir to the consumers. Such a hydraulic system with dry sump lubrication is known, for example, from DE 102019 126914 A1. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07

[0006] Since the drive unit is used to propel a motor vehicle and is located within it, it, and consequently the operating fluid, is subject to vehicle dynamics, resulting in forces that occur during longitudinal and / or lateral acceleration. This is the case, for example, when braking, accelerating, or cornering. These inertial and centrifugal forces cause the operating fluid to shift within the housing, so that in certain situations the suction point of the dry sump pump becomes exposed, preventing the operating fluid from being drawn in and pumped into the reservoir. As an undesirable consequence, the reservoir is no longer filled, and the pressure pump can no longer deliver operating fluid to the consumers, potentially causing them to overheat, run dry, and wear out.

[0007] For this reason, as disclosed, for example, in DE 102021 207694 A1, two suction points were provided, each connected to a dry sump pump designed as a gerotor pump. The suction points are selected such that at least one of them is below the fluid level of the operating medium in every operating condition. This makes it possible to draw the operating medium from the dry sump and fill the reservoir in every operating condition. The pressure pump is also designed as a gerotor pump, so that the hydraulic system comprises a total of three gerotor pumps, which are driven by an electric motor. A disadvantage of this design is that with two dry sump pumps, there are two sets of pump rotors, whose torque losses due to viscous friction must be overcome by the electric motor, even when no oil is being pumped.This increases the energy demand of the drive unit, which negatively affects its efficiency.

[0008] A further specific embodiment of such a hydraulic system with a dry sump pump capable of pumping oil from two different suction points is disclosed in DE 102019201 863 B3. In this design, a double-stroke vane pump is provided as the dry sump pump in the drive unit. By its very nature, this pump has two independent pumping sections but only one pump rotor, which causes a loss of torque. The double-stroke vane pump thus acts like two dry sump pumps with only one pump rotor. In this case, each of the two pumping sections of the double-stroke vane pump is connected to a suction point in the dry sump (ZF Friedrichshafen AG file 304124, Friedrichshafen, November 7, 2024). A disadvantage of this design is the cost of a double-stroke vane pump due to the high manufacturing precision required for this type of pump.Regardless of the double-stroke vane pump, this hydraulic system also requires a pressure pump to supply the consumers.

[0009] The object of the present invention is to provide a drive unit with an improved hydraulic system for reliable lubrication and / or cooling of the operating medium, independent of driving dynamics. In particular, the hydraulic system should have low energy consumption and be cost-effective to manufacture.

[0010] The invention solves this problem by means of the subject matter of the independent claim. The dependent claims describe a preferred embodiment.

[0011] Accordingly, a drive system for a motor vehicle comprises a machine housing section with an electric motor and a transmission housing section with a transmission, as well as a hydraulic system for cooling and / or lubricating thermal and / or mechanical consumers, such as the electric motor or the transmission. The hydraulic system also includes a first pump. The machine housing section has a first suction point, which is hydraulically connected to the first pump via a first suction line, while the transmission housing section has a second suction point, which is hydraulically connected to the first pump or to a further pump of the hydraulic system via a second suction line of the first pump.

[0012] According to the invention, the first pump is designed as a gear pump, which comprises more than two externally toothed pump gears.

[0013] Preferably, the hydraulic system comprises a reservoir to which the first pump is hydraulically connected via a first pump outlet, so that the operating medium drawn in at the first and / or second suction point can be pumped into the reservoir by means of the first pump. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07

[0014] In an advantageous embodiment of the invention, the first pump is designed as a three-wheeled external gear pump, which has three externally toothed pump gears and two suction ports. Of the three externally toothed pump gears, a first pump gear, arranged between the second and third pump gears, meshes with each of the other two pump gears.

[0015] Two meshing pump gears each form a pump unit, which functions like a separate external gear pump and generates a pressure independent of that of the other pump unit. Since the delivered volume flow rate is determined by the rotational speed and the number of teeth or the gear geometry of the first, middle pump gear, the delivered volume flows of the two pump units are equal.

[0016] This arrangement results in two pumps with only three pump gears, whereas two separate external gear pumps require a total of four pump gears. Advantageously, such a three-wheeled external gear pump not only requires less installation space but also has a higher efficiency due to the elimination of one pump gear. This is because each pump gear generates a loss torque due to viscous friction, which the drive, in this case an electric motor of the drive unit, must overcome. Especially in a pump that, as in the present application, does not generate high pressure but merely transports the operating medium, the loss torque represents a relatively large proportion of the pump's input torque. Further advantages of eliminating a pump gear include lower costs, reduced weight, and simplified assembly.

[0017] The first pump gear can preferably be driven by a drive unit with an electric motor via a pump shaft. By switching the electric motor on and off, demand-oriented and therefore energy-saving operation of the first pump is possible, for example, if too much of the operating medium has accumulated in the area of ​​the drive unit's suction points, or if the level of the operating medium in the reservoir is too low. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07

[0018] Alternatively, a mechanical drive of the first pump from the drive train is also possible.

[0019] Furthermore, it is possible that all three externally toothed pump gears have the same number of teeth. This has the advantage that all pump gears are identical parts, which has a positive effect on costs and assembly effort.

[0020] Theoretically, an alternative would be for the second and third pump gears to have fewer teeth and therefore a smaller outer diameter than the driven first pump gear. This would result in a smaller radial expansion of the first pump for the same displacement volume, thus requiring less installation space. This would also offer a weight advantage.

[0021] Preferably, the pump gears have an involute tooth profile, which offers advantages in the manufacturing of the tooth profile.

[0022] In a preferred embodiment of the invention, the first pump may have a pump housing arranged concentrically to the drive unit or pump shaft driving the first pump, wherein the first pump gear is rotationally fixed to the pump shaft, and the second and third pump gears are radially spaced from the first pump gear and arranged diametrically opposite each other. In this example, a diametrically opposite arrangement means that the second and third pump gears are offset from each other by 180°. In this context, a rotationally fixed connection of a pump gear means that the pump gear rotates at the same speed as the driving pump shaft. Any tangential play of the pump gear on the pump shaft resulting from manufacturing or assembly does not affect the rotationally fixed connection.

[0023] In an advantageous embodiment of the invention, the pump system comprises, in addition to the first pump, a second pump which is hydraulically connected to the reservoir via a third suction line and to the gearbox housing section and / or the machine housing section via a second pump outlet, such that the second pump acts as a pressure pump and can pump the operating medium from the reservoir to the thermal and / or mechanical consumers in the gearbox housing section and / or the machine housing section for cooling and / or lubrication.

[0024] In this context, it is possible that the second pump, which acts as a pressure pump, is designed as an internal gear pump with an externally toothed inner pump rotor and an internally toothed outer pump rotor.

[0025] In particular, it is possible for the second pump to be designed as a gerotor pump, with the pump's internal rotor arranged on the pump shaft and non-rotatably connected to it, and driven by the electric motor of the drive unit. This type of internal gear pump is also generally referred to as a crescent-less internal gear pump and offers the advantage of being easy to manufacture due to the absence of the crescent and exhibiting low radial dimensions with a correspondingly small installation space requirement.

[0026] Alternatively, the internal gear pump can also be designed as a sickle pump, whereby the rotors can, for example, have involute teeth.

[0027] In a further embodiment of the invention, the second pump comprises a second pump housing within which the inner and outer pump rotors are rotatably arranged. Within the pump system, the second pump housing is arranged concentrically to the pump shaft and the first pump housing, and axially spaced from the latter and the drive unit.

[0028] In an advantageous embodiment of the invention, the drive unit, the first and the second pump are arranged axially adjacent to each other on a pump axis defined by the pump shaft, thus forming a pump system which has a cylindrical outer contour around the pump axis and can therefore be easily arranged and mounted modularly in the drive unit as a compact unit. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07. As an alternative to a separate second pump acting as a pressure pump, it is possible to integrate this into the first pump by designing the first pump as a multi-geared external gear pump, which has four meshing pump gears and three suction ports.The four pump gears thus form these three pump units, each with a suction port. The suction ports of the first and second pump units are hydraulically connected to the first and second suction points, respectively, while the third suction port of the third pump unit is connected to the reservoir via the third suction line. This third pump unit then functions as a pressure oil pump. Integrating the second pump, which acts as a pressure pump, allows for a significantly shorter overall length of the pump system and a reduction in weight, as a separate pump housing is not required for the pressure pump.

[0029] In an advantageous embodiment of the invention, the flow rate of one of the two pump units of the first pump is greater than the flow rate of the second pump. This ensures that the reservoir cannot be emptied by the second pump, as the first pump would not be able to supply a sufficient quantity of the operating medium. Consequently, no operating medium could reach the consumers, and they would no longer be lubricated or cooled.

[0030] The displacement volumes of the first and second pumps are therefore selected such that the flow rate generated by the first pump, which fills the reservoir, is greater than the flow rate extracted from the reservoir by the second pump. To ensure this, one of the two pump units of the first pump—that is, half of the theoretically achievable flow rate of the first pump—must generate a larger flow rate than the second pump. This is because it is possible that the first pump can only draw the operating medium at one of its two suction points, as the other suction point is not below the fill level.

[0031] In another alternative configuration, the first pump comprises three externally toothed pump gears and one internally toothed ring gear, with the axes of rotation of the three externally toothed pump gears arranged in a line perpendicular to the axes of rotation of the pump gears (ZF Friedrichshafen AG file 304124, Friedrichshafen, November 7, 2024). Here, the internally toothed ring gear is arranged concentrically to the driven first pump gear and encloses the three externally toothed pump gears. Furthermore, the ring gear meshes with the second and third pump gears, so that the first pump has four suction ports: a first suction port between the first and second pump gears, a second suction port between the first and third pump gears, a third suction port between the second pump gear and the ring gear, and a fourth suction port between the third pump gear and the ring gear. Thus, the first pump comprises four pump units.With this variant, it is also possible to integrate the second pump as a pressure pump and even another pump as a pressure or dry sump pump into the first pump, thus reducing the overall length of the pump system.

[0032] In a particular embodiment of the drive device claimed above, it is possible for the electric machine to have a winding head cooling system, and for the winding head cooling system of the electric machine to be hydraulically connected to a gearbox compartment of the gearbox housing section. In this case, a cooling and / or lubricating medium, also referred to as the operating medium, contained in the gearbox compartment can be drawn off by the first pump at least indirectly via at least one bypass in the machine housing section, both via the first suction point and via the second suction point.

[0033] The invention will now be described in more detail with reference to the attached figures. These show

[0034] Figure 1 shows a drive device according to the invention in a motor vehicle according to the invention in a preferred embodiment;

[0035] Figure 2 shows a schematic view of a hydraulic system of the drive device according to Figure 1 according to the invention;

[0036] Figure 3 is a schematic top view of the drive device according to the invention as shown in Figures 1 and 2; ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 Figure 4 is a first schematic cross-sectional view of the drive device according to the invention as shown in Figures 1 to 3 during longitudinal acceleration of the motor vehicle;

[0037] Figure 5 shows a second schematic cross-sectional view of the drive device according to the invention as shown in Figures 1 to 4 during longitudinal deceleration of the motor vehicle;

[0038] Figure 6a shows a side view of the pump system;

[0039] Figure 6b shows a schematic longitudinal section of the pump system;

[0040] Figure 7 shows a perspective exterior view of the pump system;

[0041] Figure 8 shows a perspective partial section of the pump system with a view of the dry sump pump, and

[0042] Figure 9 shows a perspective partial section of the pump system with a view of the pressure pump.

[0043] Figure 1 shows a drive unit 100 according to the invention on a front axle of a motor vehicle 105 according to the invention. The drive unit 100 is configured to drive a drive wheel 110 of the motor vehicle 105. For this purpose, an electric machine 115 is provided, which can be operated from an electrical energy storage device 125 by means of a power converter 120. While the power converter 120 can be included in the drive unit 100, the energy storage device 125 is usually part of the motor vehicle 105. A transmission 130 is also provided to convert mechanical energy to the drive wheel 110. Optionally, the transmission 130 is configured to be driven by another drive machine (not shown), for example, a reciprocating engine. Furthermore, a differential (not shown here) can be provided to transmit the drive power to both drive wheels 110 of the front axle.An identical drive unit 100 can be effectively arranged on the rear axle of the motor vehicle 105 (not shown here) to drive the drive wheel 110 or, if a differential is provided, both drive wheels 110 of the rear axle. Thus, the motor vehicle 105 has at least two axles, with a drive unit 100 according to the invention effectively arranged on each axle. Each drive unit 100 has a hydraulic system 135 according to the invention. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 A hydraulic system 135 of the front axle is described in more detail with reference to Figure 2, whereby what has been said below applies analogously to the hydraulic system 135 of the rear axle.

[0044] The hydraulic system 135 is designed to supply one or more components of the drive unit 100, and optionally one or more other components of the motor vehicle 105, with an operating medium, hereinafter also referred to as oil, in order to cool or lubricate the components. It is assumed in the following that a hydraulic fluid, in particular an oil, is used as the operating medium for cooling and lubrication. Thus, the operating medium is to be understood as a coolant or lubricant.

[0045] The hydraulic system 135 is a dry sump system and, as shown in Figure 2, comprises a first pump 201 in the form of a dry sump pump and a second pump 205 in the form of a pressure or lubricating oil pump. The pumps 201 and 205 are arranged on a common pump shaft 210, which is rotatably driven by a drive unit 215 in the form of an electric motor to deliver a volume flow of the operating medium with each pump 201 and 205. The pumps 201 and 205, together with the pump shaft 210 and the drive unit 215, form a pump system 200, the configuration of which is shown in Figures 6a and 6b. The hydraulic system 135 further comprises a sump 220, which is hydraulically connected to an inlet side of the first pump 201 via two suction lines 225 and 230. Here, the first suction line 225 is connected to a first suction port 226 and the second suction line 230 is connected to a second suction port 231 of the first pump 201.The first pump 201, shown in detail in Figure 8, pumps the operating medium as coolant or lubricant from the sump 220 through a first pump outlet 247 into a reservoir 235. From this reservoir, the second pump 205, also referred to as a pressure pump, draws the operating medium for cooling or lubrication through a third suction line 245 and pumps it through a second pump outlet 248 to the thermal consumers and / or other components requiring lubrication shown in Figures 3 to 5. A possible embodiment of the second pump 205 is shown as pump 605 in Figures 6b and 9. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 The dashed rectangle 240 shown in the area of ​​the intake lines 225 and 230 is intended to illustrate the arrangement of that part of the drive unit 100 which is shown in the following figures 3 to 5.

[0046] The electric machine 115 of the drive unit 100 comprises a stator 315, a rotor (not shown here), and winding heads with winding head cooling systems 320 and 325 (also not shown here) located axially on both sides of the stator 315. The winding heads with the winding head cooling systems 320 and 325 are provided at the axial ends of the stator 315.

[0047] Accordingly, the drive unit 100 comprises a machine housing section 300 for accommodating the electric machine 115 (only partially shown here) and a gearbox housing section 305 for accommodating the gearbox 130 (also only partially shown here). Housing sections 300 and 305 form the housing of the drive unit 100. The machine housing section 300 has a first suction point 310, which is hydraulically connected to the first pump 201 (as shown in Figure 2) via the first suction line 225. The specific location of the suction point 310 is shown in Figures 4 and 5. The gearbox housing section 305 has a second suction point 400, which is shown in Figures 4 and 5 and is hydraulically connected to the first pump 201 (as shown in Figure 2) via the second suction line 230.

[0048] The first winding head cooling system 320, located above the stator 315 in Figure 3, is hydraulically connected via several channels, exemplified here by two arrows 330, to a gear chamber 335 of the gear housing section 305. Thus, the oil is guided into the gear housing section 305 via the first winding head cooling system 320. The second winding head cooling system 325, located below the stator 315 in Figure 3, is also hydraulically connected via several channels, exemplified here by two arrows 340, to a machine chamber 345 of the machine housing section 300. Thus, the oil is guided into the machine housing section 300 via the second winding head cooling system 325.

[0049] The machine housing section 300 further comprises two bypasses 350 and 355, which are arranged on opposite sides of the stator 315, in the representation of Figure 3 here ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 left and right of the stator 315, in the wall of the machine housing section 300 and extend from a first axial end of the machine housing section 300 to the area of ​​an opposite second axial end of the machine housing section 300 or from one end of the electric machine 115 to the opposite end of the electric machine 115.

[0050] Depending on the driving maneuver of the vehicle 105, the oil taken up in the transmission chamber 335 can be drawn off by the first pump 201 either directly at the second intake point 400 of the transmission housing section 305 and / or can be routed via one or both bypasses 350 and 355 to an annular channel 360 of the engine housing section 300. This annular channel combines the oil from the engine chamber 345 and the bypasses 350 and 355 and directs it to the first intake point 310 of the engine housing section 300. The annular channel 360 is thus arranged in the flow direction between the bypasses 350 and 355 and the first intake point 310. The first intake point 310 is designed as a bore that extends essentially axially through the wall of the engine housing section 300, starting from the annular channel 360. The first suction point 310 can connect directly to the first suction line 225 of the first pump 201.

[0051] Figures 4 and 5 also show that the intake points 310 and 400 are arranged vertically below a first axis of rotation 405 of the electric machine 155, in particular the rotor, and a second axis of rotation 410 of the gearbox 130, in this case a gear 415 of the gearbox 130, respectively. Thus, the intake points 310 and 400 are arranged as low as possible in their respective spaces in order to utilize the entire oil volume. This allows precisely the amount of oil required for cooling and lubrication to be used.

[0052] The advantages of the drive unit 100 described herein are particularly evident from the views of the drive unit 100 in Figures 4 and 5. Different driving maneuvers of the motor vehicle 105 can result in lateral accelerations, longitudinal accelerations, or longitudinal decelerations, which can have a direct influence on the flow behavior of the oil within the system, especially in the engine compartment 345 or the transmission compartment 335. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07

[0053] Figure 4 shows an example of a situation during longitudinal accelerations during an acceleration process of the motor vehicle 105, i.e., while the motor vehicle 105 is accelerating to the left in the direction of the third arrow 420. During this process, the oil flows to the right, creating a slanted oil level 425 in the gearbox compartment 335. The oil levels can equalize via the bypasses 350 and 355, thus preventing oil from accumulating in the engine compartment 345 up to the air gap between the rotor and the stator 315. This prevents churning losses and thermal coupling between the stator 315 and the rotor. The oil can then be drawn directly from the first pump 201, at least via the second suction point 400, as soon as it is needed for cooling or lubrication. In other words, the oil is fully available via the suction in the gearbox compartment 335, or at least at the second suction point 400.Depending on the driving maneuver, some of the oil can also be extracted simultaneously via the first suction point 310.

[0054] Figure 5 shows an example of a situation in the drive unit 100 during longitudinal deceleration while the vehicle 105 is braking, i.e., while the vehicle 105 is moving to the left in the direction of arrow 420 but is being braked. During this process, the oil is forced to the left, creating a slanted fill level 500, shown here by way of example in the machine housing section 300. During longitudinal deceleration, the oil can equalize via the bypasses 350 and 355, thus preventing an accumulation of oil in the machine chamber 345 up to the air gap between the rotor and the stator 315. The oil can be drawn directly from the first pump 201, at least via the first suction point 310, as soon as it is to be used for cooling or lubrication. In other words, the oil is fully available via the suction in the machine chamber 345 or at the first suction point 310.Depending on the driving maneuver, some of the oil can also be extracted simultaneously via the second suction point 400.

[0055] During lateral acceleration of the vehicle 105, the fill levels are also equalized via the bypasses 350 and 355, thus preventing oil from accumulating in the engine compartment 345 up to the air gap between the rotor and the stator 315. This eliminates the need for additional oil passages between the engine housing section 300 and the transmission housing section 305. Even during lateral acceleration, the oil remains fully available and can be drawn off at at least one of the aforementioned intake points 310 and / or 400.

[0056] Figures 6 to 9 show an embodiment of a pump system 600 according to the invention, which was schematically represented as pump system 200 in Figure 2. Figure 6a shows a side view of the pump system 600, which has a cylindrical outer contour, making it possible to arrange it in a cylindrical bore in the drive unit 100. The pump system 600 comprises a first pump 601 as a dry sump pump corresponding to the first pump 201 in Figure 2, a second pump 605 as a pressure pump corresponding to the first pump 205 in Figure 2, and a drive unit 615 designed as an electric motor corresponding to the drive unit 215 in Figure 2. Three radial seats 631, 632, and 633 are formed on the pump system 600, surrounded by a cylindrical surface, by means of which the pump system 600 is centered in a cylindrical bore formed in the drive unit 100.Furthermore, each radial seat is equipped with a radial seal 635, 636 and 637, for example in the form of an O-ring, by means of which different hydraulic connections can be sealed against each other. Thus, the pump system 600 can be inserted into the drive unit 100 and secured as a modular unit.

[0057] Figure 6b shows a schematic longitudinal section through the pump system 600. A rotor 616 of the electric motor of the drive unit 615 drives the first pump 601 and the second pump 605 via a pump shaft 610 rotatable about a shaft axis 618. The first pump 601 is designed as a three-wheeled external gear pump, comprising a first pump housing 614 and three pump gears 611, 612, and 613. The driving gear, pump gear 611, is fixedly mounted on the pump shaft 610 and drives the second 612 and third pump gears 613. The second pump gear 612 is rotatable about an axis of rotation 642, and the third pump gear 613 is rotatable about an axis of rotation 643. The first pump 601 is described in more detail in Figure 8.ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 The second pump 605 is designed as a sickle-less internal gear pump, also known as a gerotor pump or Eaton pump, and comprises, in addition to a second pump housing 624, an externally toothed inner pump rotor 621 and an internally toothed outer pump rotor 622, which engages a ring gear. The inner rotor 621 is arranged on the pump shaft 610, which is driven by the drive unit 615, and is rotationally fixed to it. The outer pump rotor 622 is driven by the inner pump rotor 621 and is rotatable about an axis of rotation that is parallel or eccentric to the shaft axis 618. Between the radial seats 631 and 632, a constriction of the cylindrical outer contour of the pump system 600 is formed, which represents a pressure pump inlet 625 through which the operating medium can flow from the reservoir 235 to the second pump 605.In the illustrated example, the first pump housing 614 and the second pump housing 624 are rigidly connected. The first pump housing 614 forms an axial contact surface 641, or axial bearing surface, for the inner pump rotor 621 and the outer pump rotor 622 with a side facing the second pump 605. An axially and radially extending recess is formed in the contact surface 641, which constitutes a pressure pump outlet 626 through which the operating medium pumped by the second pump 605 flows to the components requiring lubrication or cooling.

[0058] Figure 7 shows a perspective external view of the pump system 600. A directional arrow 736 points from the reservoir 235, from which the operating medium is drawn by the second pump 605, towards the pressure pump inlet 625. The operating medium is conveyed through the pressure pump outlet 626 for the lubrication and / or cooling of the components of the drive unit 100, as indicated by the directional arrow 742.

[0059] Symbolized by a directional arrow, the first suction line 225 leads axially through a first suction port 726 into the first pump 601. Parallel to this, symbolized by a directional arrow, the second suction line 230 leads axially through a second suction port 731 into the first pump 601. The directional arrows 735 point from the first pump 601 towards the reservoir 235 shown in Figure 2. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07. In a partial section of the pump system 600, Figure 8 shows the construction of the first pump 601. In the first pump housing 614, the externally toothed first pump gear 611 is centrally arranged on the pump shaft 610 and is rotationally fixed to it, so that it can be driven by the pump shaft 610. Radially spaced from this point, they are diametrically opposed to each other, i.e.The externally toothed pump gears 612 and 613 are arranged to rotate about the axes of rotation 642 and 643 respectively, offset by 180° from each other, and are in mesh with the first pump gear 611. Thus, the first pump 601 is designed as a three-gear external gear pump. The advantage of this pump design is that it allows for the generation of two flow rates, as with the use of two separate pumps, but without the need for a fourth pump gear.

[0060] As already explained in the introductory section on the state of the art, each pump rotor set generates a loss torque due to viscous friction, which negatively impacts the overall efficiency of a hydraulic system. Therefore, when using a three-wheeled external gear pump, the power loss is reduced by the loss of one pump gear compared to two separate external gear pumps, i.e., by 25%. This means that despite generating two flow rates, the efficiency of the three-wheeled external gear pump is significantly higher than that of two separate external gear pumps. Additional advantages include a reduced number of parts, resulting in weight and cost savings, as well as a smaller installation space requirement.

[0061] Pump gear 611, together with pump gear 612 and pump gear 613, each forms a pump unit. The displacement volume for each pump unit is determined by the gear geometry of the driven pump gear 611, independent of the gear geometry of pump gears 612 and 613. Therefore, these gears could theoretically have a smaller diameter, further reducing the radial installation space required.

[0062] The first pump housing 614 has two diametrically opposed circular axial recesses. The first recess forms a dry sump pump inlet 727 for the pump unit with the pump gears 611 and 613 and is hydraulically connected to the first suction point 310 via the first suction port 726 and the first suction line 225. Rotation of the first pump gear 611 in a direction 751 pumps the operating medium from the first dry sump pump inlet 727 to the first dry sump pump outlet 728. The dry sump pump outlet 728 is hydraulically connected to the reservoir 235, as indicated by the directional arrow 735.

[0063] The second recess forms a dry sump pump inlet 732 for the pump unit with pump gears 611 and 612 and is hydraulically connected to the second suction point 400 via the second suction port 731 and the second suction line 230. The rotation of the first pump gear 611 in the direction of rotation 751 pumps the operating medium from the second dry sump pump inlet 732 to the second dry sump pump outlet 733. This outlet is also hydraulically connected to the reservoir 235, as indicated by the directional arrow 735.

[0064] Figure 9 shows a partial section of the pump system 600, illustrating the design of a second pump 605, also referred to as a pressure pump. This pump is designed as a crescent-less internal gear pump, also known as a gerotor pump or Eaton pump. The second pump 605 comprises the externally toothed inner pump rotor 621 and the internally toothed outer pump rotor 622, which is designed as a ring gear. The inner pump rotor 621 is fixedly mounted on the pump shaft 610 and is driven by it. There is a difference of one tooth count between the inner pump rotor 621 and the outer pump rotor 622. The paths of the operating medium through the second pump, specifically the pressure pump inlet 625 and pressure pump outlet 626, are shown and described in Figure 6b.

[0065] The displacement volumes of the first pump 601 and the second pump 605 are selected such that the flow rate generated by the first pump 601, which supplies the reservoir 235, in conjunction with the rotational speed of the pumps or the pump shaft 610, is greater than the flow rate delivered by the second pump 605. This ensures that the reservoir 235 is not emptied, which would result in no operating medium reaching the consumers. To ensure that this does not occur, it is necessary that one of the two pump units of the first pump – i.e., half of the volume flow theoretically generated by the first pump 601 – generates a larger volume flow than the second pump 605, since it is possible that the first pump 601 can only draw the operating medium at one of the two suction points 310 or 400. ZF Friedrichshafen AG File 304124

[0066] Friedrichshafen 2024-11-07

[0067] Reference mark

[0068] 100 drive unit

[0069] 105 motor vehicles

[0070] 110 drive wheel

[0071] 115 electric machine

[0072] 120 power converters

[0073] 125 electrical energy storage

[0074] 130 gearbox

[0075] 135 Hydraulic system

[0076] 200 pump system

[0077] 201 first pump

[0078] 205 second pump

[0079] 210 Pump shaft

[0080] 215 Drive unit

[0081] 220 swamp

[0082] 225 first intake pipe

[0083] 226 first suction port

[0084] 230 second intake pipe

[0085] 231 second suction port

[0086] 235 Storage container

[0087] 240 rectangle

[0088] 242 Directional arrow for cooling / lubrication 245 Third intake pipe

[0089] 247 first pump outlet

[0090] 248 second pump outlet

[0091] 300 machine housing section

[0092] 305 Gearbox housing section

[0093] 310 first intake point

[0094] 315 Stator

[0095] 320 first winding head cooling ZF Friedrichshafen AG File 304124

[0096] Friedrichshafen 2024-11-07

[0097] 325 second winding head cooling 330 first arrow

[0098] 335 Gearbox compartment

[0099] 340 second arrow

[0100] 345 Engine room

[0101] 350 first bypass

[0102] 355 second bypass

[0103] 360 ring channel

[0104] 400 second intake point

[0105] 405 first axis of rotation

[0106] 410 second axis of rotation

[0107] 415 Gear of the transmission 420 Third arrow

[0108] 425 Fill level

[0109] 500 Fill level

[0110] 600 pump system

[0111] 601 first pump

[0112] 605 second pump

[0113] 610 Pump shaft

[0114] 611 first pump gear 612 second pump gear 613 third pump gear 614 first pump housing 615 drive unit, electric motor 616 rotor

[0115] 618 Shaft axle

[0116] 621 Pump inner rotor

[0117] 622 Pump outer rotor

[0118] 624 second pump housing 625 pressure pump inlet

[0119] 626 Pressure pump outlet ZF Friedrichshafen AG File 304124

[0120] Friedrichshafen 2024-11-07

[0121] 631 Radial seat

[0122] 632 Radial seat

[0123] 633 Radial seat

[0124] 635 Radial seal

[0125] 636 Radial seal

[0126] 637 Radial seal

[0127] 641 axial contact area

[0128] 642 Rotary axis pump gear

[0129] 643 Rotary axis pump gear

[0130] 726 first suction port

[0131] 727 First dry sump pump inlet 728 First dry sump pump outlet 731 Second suction port

[0132] 732 Second dry sump pump inlet 733 Second dry sump pump outlet 735 Directional arrow towards reservoir 736 Directional arrow from reservoir 742 Directional arrow towards cooling / lubrication 751 Direction of rotation of first pump gear

Claims

ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 Patent claims 1. Drive unit (100) for a motor vehicle (105), comprising a machine housing section (300) with an electric machine (115) and a transmission housing section (305) with a transmission (130), as well as a hydraulic system (135) for cooling and / or lubricating thermal and / or mechanical consumers in the machine housing section (300) and in the transmission housing section (305), wherein the hydraulic system (135) comprises a pump system (200, 600) with a first pump (201, 601), and wherein the machine housing section (300) has a first suction point (310) which is hydraulically connected to the first pump (201, 601) by a first suction line (225), wherein the transmission housing section (305) has a second suction point (400) which is connected to the first pump (201) or a further pump by a second suction line (230). The pump of the hydraulic system (135) is hydraulically connected, characterized in that the first pump (601) is designed as a gear pump which comprises more than two externally toothed gears (611 , 612, 613).

2. Drive device for a motor vehicle according to claim 1, characterized in that the first pump (601) is designed as an external gear pump, which has three externally toothed pump gears (611, 612, 613) and two suction ports (726, 731), wherein the first pump gear (611) is in engagement with both the second pump gear (612) and the third pump gear (613), and wherein the suction ports (726, 731) are each hydraulically connected to one of the two suction points (310, 400).

3. Drive device for a motor vehicle according to claim 2, characterized in that of the three pump gears (611, 612, 613) only the first pump gear (611) can be driven by a pump shaft (610) by a drive unit (615).

4. Drive device for a motor vehicle according to claim 3, characterized in that the three externally toothed pump wheels (611, 612, 613) have different or the same number of teeth. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 5. Drive device for a motor vehicle according to claim 4, characterized in that the first pump (601) has a pump housing (614) which is arranged concentrically to the drive unit (615) driving the first pump (601), wherein the first pump gear (611) is rotationally fixed to a pump shaft (610) of the drive unit (615) and the second (612) and third pump gear (613) are spaced radially apart from the first pump gear (611) and offset from each other by 180°.

6. Drive device for a motor vehicle according to claim 5, characterized in that the first pump gear (611) and the second pump gear (612) form a first pump unit with a first dry sump pump inlet (727), and the first pump gear (611) and the third pump gear (613) form a second pump unit with a second dry sump pump inlet (732), wherein the first and the second dry sump pump inlet (727, 732) are each hydraulically connected to the first (310) and the second suction point (400) by a first suction port (726) and a second suction port (731).

7. Drive device for a motor vehicle according to claim 6, characterized in that the first pump (201, 601) has a first pump outlet (247) and that the hydraulic system (135) comprises a reservoir (235), wherein both pump units of the first pump (201, 601) are hydraulically connected to the reservoir (235) via the first pump outlet (247) in such a way that the operating medium drawn in at the first and / or second suction point (310, 400) can be pumped into the reservoir (235) by means of the first pump (201, 601).

8. Drive unit for a motor vehicle according to claim 7, characterized in that the pump system (600) comprises, in addition to the first pump (201, 601), a second pump (205, 605), which is hydraulically connected by a third suction line (245) to a suction point in the reservoir (235), and is hydraulically connected by a second pump outlet (247) to the transmission housing section (305) and / or the machine housing section (300) such that the second pump (205, 605) acts as a pressure pump and the operating medium from the reservoir (235) is supplied to the cooling and / or lubrication components. ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 can promote thermal and / or mechanical consumers in the gearbox housing section (305) and / or the machine housing section (300).

9. Drive device (100) for a motor vehicle according to claim 8, characterized in that the second pump (605) acting as a pressure pump is designed as an internal gear pump.

10. Drive device (100) for a motor vehicle according to claim 9, characterized in that the second pump (605) is designed as a gerotor pump and comprises an externally toothed inner pump rotor (621) and an internally toothed outer pump rotor (622), wherein the inner pump rotor (621) is arranged non-rotatably on the pump shaft (620) and can be driven by the drive unit (615).

11. Drive device (100) for a motor vehicle according to claim 10, characterized in that the second pump (605) comprises a second pump housing (624) within which the inner pump rotor (621) and the outer pump rotor (622) are rotatably arranged, and wherein within the pump system (600) the second pump housing (624) is arranged concentrically to the pump shaft (610) and to the first pump housing (614) and adjacent to the latter and the drive unit (615).

12. Drive device (100) for a motor vehicle according to one of claims 8 to 11, characterized in that the volume flow rate of one of the two pump units of the first pump (201 , 601 ) is greater than the delivered volume flow rate of the second pump (605).

13. Drive device (100) for a motor vehicle according to claim 1, characterized in that the first pump (201) is designed as a multi-wheeled external gear pump, which has four meshing pump gears and three suction ports and thus forms three pump units, each with a suction port, wherein the suction ports (226, 231) of the first and second pump units are hydraulically connected to the first (310) and second suction point (400) and the third suction port of the third pump unit is connected to the ZF Friedrichshafen AG File 304124 Friedrichshafen 2024-11-07 Storage container (235) is connected, so that the third pump unit is effective as a pressure oil pump like the second pump (205).

14. Drive device (100) for a motor vehicle according to one of the preceding claims, characterized in that the drive unit (215, 615) comprises an electric motor with which the pump shaft (210, 610) can be driven.

15. Drive device (100) for a motor vehicle according to one of the preceding claims, characterized in that a winding head cooling (320) of the electric machine (115) is hydraulically connected to a gearbox compartment (335) of the gearbox housing section (305), wherein a cooling and / or lubricating medium received in the gearbox compartment (335) can be drawn off at least indirectly to the first intake point (310) and to the second intake point (400) via at least one bypass (350) in the machine housing section (300).

16. Electric drive axle comprising a drive unit (100) according to one of the preceding claims.

17. Motor vehicle (105) comprising a drive unit (100) according to any one of claims 1 to 15 or an electric drive axle according to claim 16.

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