Drive train unit for a motor vehicle that can be operated by an electric motor

Abstract

The present invention relates to a drive train unit (1) for a motor vehicle that can be operated by an electric motor with a conveying device (3) for a hydraulic medium, which conveying device is designed to convey the hydraulic medium in a partial load range with a first, lower volume flow and in a full load range with a second, higher volume flow, with a rotatably supported shaft (2) which has, in its interior, a first line section (4) for transporting the hydraulic medium and a second line section (5), which can be connected in parallel with respect to the first line section (4), for transporting the hydraulic medium, wherein the first line section (4) is connected to at least one first outlet opening (6) for the centrifugal-force-assisted discharge of the hydraulic medium from the shaft (2), and the second line section (5) is connected to at least one second outlet opening (7) for the centrifugal-force-assisted discharge of the hydraulic medium from the shaft (2), wherein the shaft (2) has a valve device (8) on the inlet side, which valve device allows the hydraulic medium to flow exclusively into the first line section (4) in the partial load range and allows the hydraulic medium to flow into the first line section (4) and the second line section (5) in the full load range.

Description

[0001] Drive unit for electrically powered motor vehicle

[0002] The present invention relates to a drive train unit for an electrically powered motor vehicle with a conveying device for a hydraulic medium, which is configured to convey the hydraulic medium in a partial load range with a first, lower volume flow rate and in a full load range with a second, higher volume flow rate.

[0003] According to current technology, components of a powertrain that have rotating parts, such as an electric motor, a DHT transmission (Dedicated Hybrid Transmission), wet clutches, hybrid modules, or CVT transmissions (Continuously Variable Transmission), are lubricated, actuated, or cooled by a rotating shaft. This is achieved by transporting a suitable hydraulic fluid, such as oil, brake fluid, or coolant, through the shaft and injecting / delivering it to the relevant points through an (outlet) bore. The disadvantages of this solution are explained below using the example of oil lubrication.

[0004] Due to the rotating shaft, a centrifugal force acts on the oil within the shaft, forcing it into the outlet bores. Depending on the rotational speed, the centrifugal force increases, creating a suction effect on the oil. This results in a vacuum in the oil supply channel formed within the shaft. The bore closest to the oil supply draws away the entire volume of oil due to centrifugal force. Consequently, the other lubrication or cooling points are no longer supplied. While adjusting the bore diameters can reduce the risk of, for example, an electric motor not being effectively cooled or components like gears or bearings not being lubricated at high speeds, this is not a satisfactory solution.

[0005] It is not strictly necessary for an electric motor to be actively cooled in the low-load and partial-load ranges, whereas cooling of the electric motor is mandatory in the full-load range. Other components, such as bearings, must be lubricated at all times, as a failure of lubrication can lead to the destruction of the bearing within a very short time. The object of the present invention is to provide a drive train unit for an electrically powered vehicle that enables efficient lubrication and / or cooling in both the partial-load and full-load ranges.

[0006] According to the invention, this problem is solved by a drive train unit for an electrically powered motor vehicle according to claim 1, comprising a conveying device for a hydraulic medium, which is configured to convey the hydraulic medium in a partial load range with a first, lower volume flow rate and in a full load range with a second, higher volume flow rate, comprising a rotatably mounted shaft which has inside a first line section for transporting the hydraulic medium and a second line section for transporting the hydraulic medium which can be connected in parallel to the first line section, wherein the first line section is connected to at least a first outlet opening for the centrifugal force-assisted exit of the hydraulic medium from the shaft, and the second line section is connected to at least a second outlet opening for the centrifugal force-assisted exit of the hydraulic medium from the shaft.

[0007] Since the shaft has a valve assembly on the inlet side that allows the hydraulic fluid to flow exclusively into the first line section in the partial load range, and allows the hydraulic fluid to flow into both the first and second line sections in the full load range, efficient lubrication and / or cooling is enabled in both the partial and full load ranges. In particular, power loss is minimized.

[0008] Preferably, the first pipe section is formed parallel to the second pipe section within the shaft. This enables efficient lubrication and / or cooling in both partial and full load ranges.

[0009] Preferably, the first pipe section is concentric with the second pipe section and is preferably arranged within the second pipe section. This enables efficient lubrication and / or cooling in both partial and full load operation. It is advantageous if the valve assembly includes a pressure-independent connection between the conveying device and the first pipe section and a pressure-dependent connection, preferably in the form of a spring-loaded pressure relief valve, between the conveying device and the second pipe section. This also enables efficient lubrication and / or cooling in both partial and full load operation.

[0010] It is advantageous if the shaft, or another shaft, is rotatably mounted in a housing by at least one bearing, and if the first outlet opening is located near or within the bearing to allow the hydraulic fluid to be supplied to the bearing during operation of the drive unit. This enables efficient lubrication and / or cooling under partial and full load conditions.

[0011] Furthermore, it is advantageous if the shaft carries at least one gear, and if the first or a further first outlet opening is located near or within the gear to allow the hydraulic fluid to be supplied to the gear during operation of the drive train unit. This enables efficient lubrication and / or cooling under partial and full load conditions.

[0012] Furthermore, it is advantageous if the shaft carries at least one component of a wet coupling, and if the first or a second outlet opening is located near or within the coupling to allow the hydraulic fluid to be supplied to the coupling during operation of the drivetrain unit. This enables efficient lubrication and / or cooling under partial and full load conditions.

[0013] It is also advantageous if the shaft carries at least one rotor of an electric machine, and if the second outlet opening is located near or within the rotor to allow the hydraulic fluid to be supplied to the rotor during operation of the drive unit. This enables efficient lubrication and / or cooling under partial and full load conditions. Preferably, the valve assembly is arranged axially within the drive unit between an end face of the shaft, rotatably mounted in or within the housing, and the rotor. This enables efficient lubrication and / or cooling under partial and full load conditions.

[0014] It is advantageous if the diameter of the first outlet differs from the diameter of the second outlet. This enables efficient lubrication and / or cooling under partial and full load conditions.

[0015] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying figures, which show preferred embodiments. The invention is in no way limited by the purely schematic figures, it should be noted that the figures are not dimensionally accurate and are not suitable for defining size relationships. Features not expressly identified as essential to the invention are to be understood as optional. The figures show:

[0016] Figure 1 shows a sectional view of an embodiment of a drive train unit with a conveying device for a hydraulic medium operating in a partial load range and with a valve device that is partially closed.

[0017] Figure 2 shows a detailed view of the drive train unit from Figure 1.

[0018] Figure 3 shows a sectional view of the embodiment of the drive train unit with the hydraulic fluid delivery device operating in a full-load range and with the valve device fully open, and

[0019] Figure 4 shows a detailed view of the drive train unit from Figure 3.

[0020] Figures 1 to 4 show an embodiment of a powertrain unit 1 for an electrically powered motor vehicle. The electrically powered motor vehicle can be a purely electric vehicle or a hybrid vehicle.

[0021] The drive unit 1 has a pumping device 3 for a hydraulic fluid. The pumping device 3 is designed to pump the hydraulic fluid through a supply line 18 of the drive unit 1 with a first, lower flow rate in a partial load range and with a second, higher flow rate in a full load range. Furthermore, the drive unit 1 has a shaft 2 rotatably mounted about a pivot axis D in a housing 9 of the drive unit 1, which will be discussed in more detail below. The supply line 18 can be fixed to the housing and, in particular, can be partially or completely integrated into the housing 9.

[0022] The conveying device 3 is in particular a pump. This can be driven by a separate drive unit such as an electric motor, preferably rotary, but can also be driven directly or indirectly by the shaft 2.

[0023] The flow of the hydraulic fluid, which may be, for example, a lubricant and / or a coolant, is shown schematically in Figures 1 to 4 by corresponding arrows within the supply line 18 or the subsequent line sections 4, 5 and outlet openings 6, 7.

[0024] The rotatably mounted shaft 2 has internally a first line section 4 for transporting the hydraulic fluid and a second line section 5 for transporting the hydraulic fluid. The first line section 4 is connected to at least one first outlet opening 6 for the centrifugally assisted exit of the hydraulic fluid from the shaft 2. The second line section 5 is connected to at least one second outlet opening 7 for the centrifugally assisted exit of the hydraulic fluid from the shaft 2.

[0025] In this context, "centrifugal force-assisted discharge" means that the hydraulic fluid is pressurized by the pumping device 3 and flows under this pressure through the supply line 18, the line sections 4, 5 in the shaft 2, and the discharge openings 6, 7 in the shaft 2. However, the discharge openings 6, 7 in the wall of the shaft 2 are arranged such that the rotation of the shaft 2 about the axis of rotation D during operation of the drive train unit 1 flings the hydraulic fluid out of the discharge openings 6, 7. Therefore, the discharge openings 6, 7 are preferably formed substantially perpendicular to the axis of rotation D, i.e., as transverse bores extending in the radial direction R of the drive train unit 1, in the wall of the shaft 2.

[0026] The shaft 2 has a valve assembly 8 on its inlet side, i.e., upstream with respect to the line sections 4 and 5 and downstream with respect to the supply line 18. With reference to Figures 1 to 4, the valve assembly 8 is arranged in a left end face 17 of the shaft 2, i.e., in a region where the shaft 2 is rotatably mounted in the housing 9 by a rolling bearing, preferably a ball bearing. This rolling bearing can be lubricated and / or cooled directly by hydraulic fluid branched off from the supply line, or it can be lubricated and / or cooled by hydraulic fluid from within the shaft 2 itself, which will be explained further below with reference to a bearing 10.

[0027] The valve assembly 8 is designed such that, in the partial load range, it allows the hydraulic fluid to flow exclusively into the first line section 4, and in the full load range, it allows the hydraulic fluid to flow into both the first line section 4 and the second line section 5. The valve assembly 8 allows the second line section 5 to be switched in parallel with the first line section 4, i.e., supplied with hydraulic fluid in parallel with the first line section 4.

[0028] Both the first conduit section 4 and the second conduit section 5 extend within the shaft 2 in the axial direction A of the drive train unit 1. Thus, the first conduit section 4 is formed parallel to the second conduit section 5 within the shaft 2. In particular, the first conduit section 4 is concentric with the second conduit section 5 and is preferably arranged within the second conduit section 5. With reference to Figures 1 to 4, the two conduit sections 4 and 5 are either closed on the right-hand side or have small leakage openings there. Specifically, the shaft 2 is preferably designed as a hollow shaft, at least in the region of the two conduit sections 4 and 5. The inner surface of the shaft 2 wall defines the second conduit section 5.The first line section 4 is preferably designed as a one- or multi-part distributor tube inserted into the hollow shaft, such that the second line section 5 is formed between the inside of the wall of the shaft 2 and the outside of the distributor tube, while the first line section 4 extends inside the distributor tube.

[0029] Furthermore, the distributor pipe, preferably made of plastic, has distributor sections in which it contacts the inside of the wall of the shaft 2 and in which the distributor sections, together with the wall of the shaft 2, form the first outlet openings 6. Thus, the first outlet openings 6 are in fluidic communication with the first pipe section 4.

[0030] The second outlet openings 7 are formed exclusively in the wall of the shaft 2, which is designed as a hollow shaft, whereby the second outlet openings 7 are in fluidic communication with the second line section 5.

[0031] The diameter of the first outlet openings 6 differs from the diameter of the second outlet openings 7. In particular, the diameter of the first outlet openings 6 is smaller than the diameter of the second outlet openings 7. Furthermore, the diameters of the outlet openings 6 and 7 can vary depending on the distance to the valve assembly 8 in order to prevent a possible insufficient supply of hydraulic fluid at the end of the shaft 2, i.e., with reference to Figures 1 and 3 on the right-hand side.

[0032] The valve assembly 8 includes a pressure-independent connection between the conveying device 3 or the supply line 18 and the first line section 4, and a pressure-dependent connection, preferably in the form of a spring-loaded pressure valve, between the conveying device 3 or the supply line 18 and the second line section 5.

[0033] The distributor pipe, inside which the first pipe section 4 is formed, is preferably pressed or clipped into a distributor disc 21 of the valve assembly 8. The distributor disc 21 has a throttle bore 23 in its radial inner region and, in its radial outer region, the spring-loaded pressure valve with one or more passages, which are sealed by a sealing element 20 pressed against it by a valve spring 19. The valve spring 19, by its preload force and the effective area of ​​the sealing element 20, defines the opening pressure of the valve assembly 8 for the full-load range, while the throttle bore 23 enables the permanent, i.e., pressure-independent, connection between the conveying device 3 or the supply line 18 and the first pipe section 4 in both the partial-load and full-load ranges.

[0034] As an alternative to the disc-shaped sealing element 20, the spring-loaded pressure valve as part of the valve assembly 8 can also have several spring-loaded balls.

[0035] With a given throttle bore 23, the pressure in the space in front of the distributor disc 21 is relatively linear to the volume flow rate delivered by the pumping device 3 or the pump. If the valve spring 19 and the passages in the radial outer area of ​​the distributor disc 21 are dimensioned accordingly, a change in the volume flow rate of the pumping device 3 can cause the sealing element 20 or the spring-loaded pressure valve of the valve assembly 8 to open or close. This allows the hydraulic fluid to flow into the second line section 5 via a single or multiple perforated passage 22, in which the valve spring 19 is supported in the axial direction A (full load range, spring-loaded pressure valve open, see in particular Figure 4). Alternatively, this connection can be interrupted, and only the first line section 4 is supplied with hydraulic fluid through the throttle bore 23 (partial load range, spring-loaded pressure valve closed, see in particular Figure 2).

[0036] In the illustrated embodiment of the drive train unit 1, the shaft 2 carries two rotors 15, which, together with their respective associated stators 16, form the main components of two electric machines 14. Specifically, with reference to Figures 1 and 3, the left of the two rotors 15 is directly supported by the shaft 2, while the right of the two rotors 15 is only indirectly supported by the shaft 2, as will be explained in more detail below. Specifically, with reference to Figures 1 to 4, one of the two electric machines 14 is arranged on the left side. Its rotor 15 is fixed to the shaft 2 to the right of the aforementioned rolling bearing, by which the left end face 17 of the shaft 2 is rotatably mounted in the housing 9, thus ensuring that the rotor 15 is directly supported by the shaft 2. Within the rotor 15, there are second outlet openings 7 in the wall of the shaft 2, i.e.,The valve assembly 8 is arranged near or within the rotor 15 to allow the supply of hydraulic fluid to the rotor 15 during operation of the drive train unit 1. The valve assembly 8 is arranged axially A between the end face 17 of the shaft 2, which is rotatably mounted in the housing 9, and the rotor 15.

[0037] Furthermore, with reference to Figures 1 and 3, another of the two electric machines 14 is arranged on the right-hand side. Its rotor 15 is not fixed to the shaft 2 in a rotationally fixed manner, but has a separate rotor shaft, which is designed as a (further) hollow shaft. This shaft is rotatably supported on the shaft 2 by a bearing 10, preferably a needle bearing, so that the rotor 15 is indirectly supported by the shaft 2. Within the rotor 15, or within the separate rotor shaft, second outlet openings 7 are arranged in the wall of the shaft 2, i.e., near or within the rotor 15, to allow the supply of hydraulic fluid to the rotor 15 during operation of the drive train unit 1. The rotor shaft can also be provided with through-holes for this purpose.

[0038] In the axial direction A between the two electric machines 14, the rotor shaft of the right-hand electric machine 14, in the illustrated embodiment, is rotatably mounted in the housing 9 by at least one bearing 10, which is preferably designed as a (further) rolling bearing, in particular as a ball bearing. One or more first outlet openings 6 are arranged near the bearing 10 to allow the hydraulic fluid to be supplied to the bearing 10 during operation of the drive train unit 1. For this purpose, the rotor shaft can also be provided with (further) through-openings. One or more first outlet openings 6 are likewise arranged near the aforementioned needle bearing, by which the rotor shaft is rotatably mounted on the shaft 2, to allow the hydraulic fluid to be supplied to the needle bearing during operation of the drive train unit 1.

[0039] In the illustrated embodiment, a wet coupling 13 is arranged axially A between the two electric machines 14. The rotor shaft of the right-hand electric machine 14 can be rotatably connected to and disconnected from the shaft 2 by means of this coupling. The shaft 2 directly supports at least one component 12 of the wet coupling 13, which in the illustrated embodiment is the inner plate carrier with the inner plates suspended thereon. The inner plate carrier is fixedly mounted on the shaft 2 and is, in particular, formed integrally with the shaft 2. One or more first outlet openings 6 are arranged near or within the coupling 13 to allow the hydraulic fluid to be supplied to the coupling 13 during operation of the drive train unit 1.

[0040] The shaft 2 can further carry at least one gear 11, which is either rotationally fixed to the shaft 2 or rotatably mounted on the shaft 2. In addition to the illustrations in Figures 1 to 4, one or more first outlet openings 6 can be arranged near or within the gear 11 to allow the hydraulic fluid to be supplied to the gear 11 during operation of the drive train unit 1.

[0041] The previously described design makes it possible to provide continuous lubrication and cooling of the bearings 10, the coupling 13, and, if applicable, the gears 11 under partial load using a comparatively small amount of hydraulic fluid. The resulting power loss is comparatively low. Cooling of the electric motor(s) 14 is not required under partial load, as the heat generated there can be dissipated even without internally supplied hydraulic fluid.

[0042] In the full-load range, the electric machine 14 is additionally cooled with a comparatively large quantity of hydraulic fluid to be accelerated. Although the resulting power loss is comparatively high, the proportion of time during which the drive unit 1 operates in the full-load range is comparatively small. Therefore, across all load ranges of the drive unit 1, the total power loss expended on pumping the hydraulic fluid, and thus unavailable for propelling the vehicle, remains comparatively low.

[0043] The previously described embodiment relates to a drive train unit 1 for an electrically powered motor vehicle with a conveying device 3 for a hydraulic fluid, which is designed to convey the hydraulic fluid in a partial load range with a first, lower volume flow rate and in a full load range with a second, higher volume flow rate, with a rotatably mounted shaft 2, which has inside a first line section 4 for transporting the hydraulic fluid and a second line section 5, which can be connected in parallel to the first line section 4, for transporting the hydraulic fluid, wherein the first line section 4 is connected to at least a first outlet opening 6 for the centrifugal force-assisted exit of the hydraulic fluid from the shaft 2, and the second line section 5 is connected to at least a second outlet opening 7 for the centrifugal force-assisted exit of the hydraulic fluid from the shaft 2.wherein the shaft 2 has a valve device 8 on the inlet side which, in the partial load range, allows the hydraulic fluid to flow exclusively into the first line section 4, and which, in the full load range, allows the hydraulic fluid to flow into the first line section 4 and the second line section 5.

[0044] List of reference signs

[0045] 1 drive train unit shaft

[0046] Conveyor system, first pipe section, second pipe section, first outlet opening

[0047] 7 second exit opening

[0048] 8 Valve assembly

[0049] 9 cases

[0050] 10 warehouses

[0051] 11 gear

[0052] 12 components

[0053] 13 Clutch

[0054] 14 electric machine

[0055] 15 Rotor

[0056] 16 Stator

[0057] 17 Front

[0058] 18 Supply line

[0059] 19 Valve spring

[0060] 20 sealing elements

[0061] 21 Distributor disc

[0062] 22 Passage area

[0063] 23 Throttle bore

[0064] A axial direction

[0065] D axis of rotation

[0066] R radial direction

Claims

Patent claims 1. Powertrain unit (1) for an electrically powered motor vehicle with a conveying device (3) for a hydraulic fluid, which is configured to convey the hydraulic fluid in a partial load range with a first, lower volume flow rate and in a full load range with a second, higher volume flow rate, with a rotatably mounted shaft (2) which has inside a first line section (4) for transporting the hydraulic fluid and a second line section (5) which can be connected in parallel to the first line section (4) for transporting the hydraulic fluid, wherein the first line section (4) is connected to at least a first outlet opening (6) for the centrifugal force-assisted exit of the hydraulic fluid from the shaft (2), and the second line section (5) is connected to at least a second outlet opening (7) for the centrifugal force-assisted exit of the hydraulic fluid from the shaft (2),wherein the shaft (2) has a valve device (8) on the inlet side which, in the partial load range, allows the hydraulic fluid to flow exclusively into the first line section (4), and which, in the full load range, allows the hydraulic fluid to flow into the first line section (4) and the second line section (5).

2. Drive train unit (1) according to claim 1, wherein the first line section (4) is formed parallel to the second line section (5) inside the shaft (2).

3. Drive train unit (1 ) according to claim 1 or 2, wherein the first line section (4) is formed concentrically with the second line section (5), and is preferably arranged within the second line section (5).

4. Drive train unit (1) according to one of claims 1 to 3, wherein the valve assembly (8) provides a pressure-independent connection between the conveying device (3) and the first line section (4) and a pressure-dependent connection, preferably in the form of a spring-loaded pressure valve, between- includes the conveying device (3) and the second line section (5).

5. Drive train unit (1 ) according to one of claims 1 to 4, wherein the shaft (2) or a further shaft is rotatably mounted in a housing (9) by at least one bearing (10), and wherein the first outlet opening (6) is arranged near or inside the bearing (10) to allow the hydraulic medium to be supplied to the bearing (10) during operation of the drive train unit (1 ).

6. Drive train unit (1 ) according to one of claims 1 to 5, wherein the shaft (2) carries at least one gear (11 ), and wherein the or a further first outlet opening (6) is arranged near the gear (11 ) or inside the gear (11 ) to enable a supply of hydraulic fluid to the gear (11 ) during operation of the drive train unit (1 ).

7. Drive train unit (1) according to any one of claims 1 to 6, wherein the shaft (2) carries at least one component (12) of a wet coupling (13), and wherein the or a further first outlet opening (6) is arranged near the coupling (13) or within the coupling (13) to supply the hydraulic medium to the coupling (13) during operation of the drive train unit (1) to enable.

8. Drive train unit (1) according to any one of claims 1 to 7, wherein the shaft (2) carries at least one rotor (15) of an electric machine (14), and wherein the second outlet opening (7) is located near or in the rotor (15) to allow the supply of hydraulic fluid to the rotor (15) during operation of the drive train unit (1 ).

9. Drive train unit (1) according to claim 8, wherein the valve assembly (8) is rotatably arranged in the axial direction (A) of the drive train unit (1) between a is arranged on the end face (17) of the shaft (2) and the rotor (15) mounted on the housing (9).

10. Drive train unit (1 ) according to any one of claims 1 to 9, wherein the diameter of the first outlet opening (6) differs from the diameter of the second outlet opening (7).

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