Electric drive system for motor vehicle

Abstract

The invention relates to an electric drive system (1) for a motor vehicle, comprising: an electric machine (2) having a rotor (3) with a rotor shaft (4); a planetary gear stage (13) having a sun gear (11), a planet carrier (8) and a corresponding planet gear (10) and a ring gear (12), the rotor shaft (4) being connected to the sun gear (11) in a rotationally fixed manner, the planet carrier (8) having a planet carrier shaft (16) which is arranged coaxially to and axially adjacent to the rotor shaft (4), the planet carrier shaft (16) is supported relative to a housing (5) by means of a first bearing (14), the housing (5) having a circular opening (20) through which the planet carrier shaft (16) passes, the housing (5) having a first oil duct (21) which opens into the circular opening (20), and the planet carrier shaft (16) having a swivel joint (25) in the axial region of the opening (20) with respect to the axis of rotation (A) thereof, the planet carrier shaft (16) has at least one first bore (26) extending in the axial direction (a) and connected at one end thereof to the swivel joint (25), the rotor shaft (4) has a second bore (32) extending in the axial direction, and the first bore (26) is connected to the second bore (32).

Description

Technical Field

[0001] The invention relates to an electric drive system for a motor vehicle, comprising an electric machine and a planetary gear stage which is arranged adjacent to the electric machine in an axial direction. Background Art

[0002] Planetary transmission stages that can be used, for example, for electric drive systems for motor vehicles are already well known in the prior art. For example, DE 10 2019 114 139 B3 can be referenced here, which shows a motor vehicle transmission for coupling an electric motor to a drive train. The planetary transmission stage and the electric motor are axially adjacent to each other. Other planetary transmission stages suitable for electric drive systems are also disclosed in DE 8535076 U1, CN 1 01 338 812A, JP S63-197 641U, DE 103 23 254A1, US 2016 / 0265 652A1 and US 5 597 370 A.

[0003] A planetary gear stage is known from the generic DE 10 2014 220 309 A1, in which lubricating oil is firstly conducted from an oil gallery from a housing into a planet carrier shaft of a planet carrier and from there into an axially adjacent and coaxially arranged rotor shaft. Summary of the invention

[0004] The object of the present invention is to specify an improved electric drive system with a planetary gear stage which is optimized in particular with regard to the lubricating oil supply.

[0005] According to the invention, this object is achieved by an electric drive system for a motor vehicle having the features of claim 1. Advantageous embodiments and developments of the electric drive system for a motor vehicle according to the invention are derived from the dependent claims associated therewith.

[0006] The electric drive system for a motor vehicle according to the invention comprises an electric machine and a planetary gear stage having a sun gear, a planetary carrier and its associated planetary gears, and a ring gear.

[0007] The rotor shaft itself is connected or connectable to the sun gear in a torque-transmitting manner. The rotor shaft can be connected to the sun gear in a rotationally fixed manner. However, one or more transmission stages and / or switching elements can also be arranged between the rotor shaft and the sun gear.

[0008] The planetary gear carrier has a planetary carrier shaft, which is arranged coaxially with the rotor shaft and adjacent to the rotor shaft in the axial direction. The planetary carrier shaft of the planetary gear carrier is supported relative to the housing by means of a first bearing, and the housing has a circular opening for the planetary carrier shaft to pass through. The housing includes a first oil channel leading to this circular opening. The planetary carrier shaft has a swivel joint in the axial region of the opening with respect to its rotation axis so as to receive the lubricating oil flowing in through the first oil channel. The planetary carrier shaft also has at least one first hole extending in the axial direction, and the first hole is connected to the swivel joint at one end thereof so that the oil can flow through the first hole. The rotor shaft has a second hole extending in the axial direction, and the second hole is particularly arranged coaxially with the rotor shaft and extends inside the rotor shaft. This means that the rotor shaft is designed as a hollow shaft at least in the section facing the planetary carrier shaft. The first hole in the planetary carrier shaft and the second hole in the rotor shaft are connected to each other here, so that the oil entering the first hole of the planetary carrier shaft via the swivel joint can enter the rotor shaft rotating at a high speed. As a result, the rotating component mounted on the rotor shaft side can be ideally supplied with lubricating oil while ensuring a simple and compact structure.

[0009] The terms "coaxial", "axial" and "radial" refer here to the respective arrangement or orientation relative to the axis of rotation of the planetary gear stage, which can also be referred to as the main axis of rotation. The electric machine or its rotor as well as the elements of the planetary gear stage, i.e. the sun gear, the ring gear and the planet carrier, rotate about the axis of rotation. If such expressions are relative to another axis, for example the axis of rotation of a planetary gear, this will be explicitly stated accordingly.

[0010] In this case, provision is made for a nozzle to be arranged on the end face of the planet carrier shaft facing the rotor shaft, the nozzle opening into the second bore so that the lubricating oil flow flowing to the nozzle is discharged onto the rotor shaft, which usually rotates at a high speed.

[0011] According to the invention, a retaining ring is provided, which is arranged in the second hole so as to overlap the nozzle axially at least partially. The cooperation between the nozzle and the retaining ring can prevent the lubricating oil from leaking through the gap between the rotor shaft and the planetary carrier shaft. Here, according to the solution of the invention, the shaft seal between the planetary carrier shaft and the rotor shaft can be omitted. The shaft seal for the rapidly rotating rotor shaft may cause significant friction losses.

[0012] According to an advantageous improvement, the retaining ring has a disk at its end facing the planet carrier shaft, which extends radially inwards from the inner surface of the second hole, wherein the disk is completely covered by the nozzle in the axial direction. The disk effectively prevents the lubricating oil from flowing back in the direction of the planet carrier shaft in a simple and cost-effective manner.

[0013] The retaining ring advantageously has a cylindrical portion which bears against the wall of the second bore and is connected to the disk portion.

[0014] The disk advantageously has a preferably circular opening radially on the inside, wherein the nozzle has a second cylindrical section which axially passes through the opening. The disk and the advantageously circular opening are advantageously arranged coaxially with the axis of rotation of the planetary gear stage.

[0015] The term "axially overlapping" means that two at least partially overlapping elements are at least partially arranged in the same axial coordinate region. "Radially inside" means that when the first element is arranged in a smaller radial coordinate region than the second element, the first element is arranged radially inside the second element.

[0016] According to a very advantageous development of the electric drive system according to the invention, the region with the sun wheel, which is connected to the rotor shaft in a rotationally fixed manner as described above, can be arranged directly axially adjacent to the nozzle. The supply of lubricating oil via the nozzle is therefore carried out in the region of the sun wheel, in particular so that the nozzle opening into the second hole of the rotor shaft is in contact with or partially overlaps the region of the sun wheel in the axial direction.

[0017] In the context of the present invention, “connected in a rotationally fixed manner” means that two coaxial elements are connected in such a way that they rotate at the same angular speed.

[0018] According to another very advantageous improvement of the electric drive system of the present invention, the first hole is arranged parallel to the rotation axis of the planet carrier shaft. The first hole or all the first holes (provided that a plurality of such holes are provided in the circumferential direction) are arranged parallel to the rotation axis of the planet carrier shaft. The planet carrier shaft can be designed as a hollow shaft, for example, and the first hole or the plurality of first holes are located in the hollow shaft.

[0019] According to an advantageous improvement of the electric drive system of the present invention, it is provided that the rotor shaft has at least one second oil channel, which connects the rotor shaft surface to the second hole. The oil from the area of ​​the second hole, which preferably reaches the area of ​​the second hole through a nozzle or a connecting structure between the two holes that may adopt other designs, enters the radially outer area of ​​the rotor shaft through the second oil channel and can lubricate the bearings therein accordingly, or is thrown radially outward by the rotation of the rotor shaft, so as to supply lubricating oil to the corresponding bearings, such as the rotor bearing, the second bearing of the planetary gear carrier, etc.

[0020] The second oil channel can be designed in particular radially in order to ensure an ideal flow, in principle, as long as it can connect the corresponding elements in the manner described, the course of the second oil channel therefore always having, at least in places, a radial component.

[0021] Another very advantageous design of the electric drive system according to the invention further provides that the planetary gears are arranged on the planetary gear pins, wherein an oil baffle is arranged on the planetary gear pins so that the oil thrown radially outward from the rotor shaft is introduced into the planetary gear pins designed as hollow cylinders through the oil baffle. In this way, the lubricating oil reaches the area of ​​the planetary gear pins simply and efficiently. According to another very advantageous embodiment of this variant of the electric drive system according to the invention, it can be provided that the planetary gear pins have a third oil channel, which connects the inner cavity of the hollow cylinder to the outer surface of the planetary gear pins that carries the planetary gears. The oil that enters the hollow cylinder through the oil baffle thus reaches the outer surface of the planetary gear pins, on which the planetary gears are arranged via their corresponding supporting means. The oil can thus lubricate the planetary gears or their supporting means accordingly, wherein here, the third oil channel also preferably extends accordingly from the radial inside to the radial outside with respect to the rotation axis of the planetary gear stage, so as to facilitate the oil conveying by centrifugal force.

[0022] According to another very advantageous design of the electric drive system according to the invention, it can now also be provided that the fourth oil channel is arranged in the housing radially outside the ring gear. Through the fourth oil channel, which can also extend radially but is not necessary, the lubricating oil can now flow out from the area of ​​the electric motor and the planetary gear stage accordingly, so as to return to the lubricating oil circuit and, for example, after passing through a filter and a conveying device, via the first oil channel to supply the rotary oil connection again, and thus indirectly to the interior of the rotor shaft as the starting point of the above-mentioned lubrication.

[0023] Another advantageous embodiment of the electric drive system according to the invention can also provide that the housing has a housing base and a housing cover, wherein the first oil channel is arranged in the wall of the housing cover, preferably such that the first oil channel extends at least partially parallel to the wall surface. In this way, the oil is guided through the housing cover to the swivel joint of the planet carrier shaft in a simple and efficient manner, wherein the oil channels as described above can in particular provide a circulation circuit for the oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further advantageous embodiments of a planetary gear stage and of an electric drive system for a motor vehicle also emerge from the exemplary embodiments described in greater detail below with reference to the accompanying drawings, in which:

[0025] Figure 1 A schematic diagram showing an electric drive system for a motor vehicle according to one embodiment of the present invention;

[0026] Figure 2 A partial cross-sectional view of an electric drive system using an embodiment of the planetary gear stage of the present invention is shown. DETAILED DESCRIPTION

[0027] exist Figure 1An electric drive system 1 is shown in the diagram of . It has an electric motor 2, which is designed, for example, as an axial flux motor. It comprises a stator 30 and a two-part rotor 3, which is arranged here in a rotationally fixed manner relative to a housing 5 and which is connected in a rotationally fixed manner to a rotor shaft 4. The rotor shaft 4 forms an input shaft to a planetary gear stage 13 and is connected in a rotationally fixed manner to a sun gear 11 or can be connected as required, which is not explicitly shown here. The planetary gear stage 13 also comprises a ring gear 12, which is connected in a rotationally fixed manner to the housing 5. The planetary gear carrier 8 is connected in a rotationally fixed manner to an output shaft 18, which outputs power from the electric drive system 1, such an output device being denoted by the reference numeral 7 and shown at Figure 1 As shown by the arrow in the diagram.

[0028] exist Figure 2 A portion of the electric drive system 1 is shown in the diagram. Only the half of the rotor 3 located on the right side in the motor 2 or on the right side of the stator 30 is shown here, and the rotor is supported relative to the housing 5 by a rotor bearing 6 (which is preferably designed as a rolling bearing, especially preferably designed as a mitered ball bearing). The rotor is connected to the rotor shaft 4 designed as a multi-piece in a rotationally fixed manner. The rotor shaft is supported indirectly by the rotor bearing 6 of the rotor 3 and is also supported on the housing by a needle bearing 28. On the side of the motor 2 located at the far end in the axial direction a, an output device 7 leading to a motor vehicle wheel or shaft reducer (such as a differential) is schematically shown. The output device 7 is here connected to the planetary gear carrier 8 as the output member of the planetary transmission stage 13 in a rotationally fixed manner via the output shaft 18 by means of a spline shaft toothing 19.

[0029] The axial direction a is arranged parallel to the rotation axis A of the planetary gear stage 13. The rotation axis A is the common rotation axis of the sun gear 11, the ring gear 12 and the planetary carrier 8. The rotor 3 of the electric machine 2 is also arranged coaxially to the rotation axis A and thus to the planetary gear stage 13.

[0030] The planetary gear carrier 8 has planetary gear pins 9 protruding in the axial direction a toward the electric motor 2. The planetary gears 10 are supported on the planetary gear pins 9 by means of planetary gear bearings 27, which are designed here in the form of two corresponding mitered ball bearings. The sun gear 11 meshes with the planetary gears 10 on the radial inside, and the sun gear is formed by the tooth row of the rotor shaft 4. The ring gear 12 supplements this structure to form a planetary gear stage 13 for converting torque between the rotor 3 and the output device 7. The ring gear 12 is connected to the housing 5 in a rotationally fixed manner.

[0031] The planet carrier 8 thus comprises a planet pin 9 which is connected to an element 14 of the planet carrier 8 in a rotationally fixed manner, which is referred to as a web. In the embodiment shown here, the planet gears 10 are inserted onto the planet pins 9 together with two mitered ball bearings of the planet gear bearing 27. Alternatively, for example, a separate rolling bearing can be provided. The planet carrier 8, which consists of the web 14 and the planet pin 9, is designed as a one-piece forging. After the planet gears 10 and the two mitered ball bearings of the planet gear bearing 27 have been mounted, a web support ring 15 is now mounted on the side of the planet carrier 8 facing away from the web 14. After the planet gears 10 have been mounted, the mitered ball bearings of the planet gear bearing 27 can now be preloaded by pressing the web support ring 15 onto the web 14. The web support ring 15 is then welded to the web 14 in this preloaded position.

[0032] Observed along the axial direction a of the rotation axis A, Figure 1 On the right side of the illustration of the planet carrier 8, the part of the planet carrier 8 surrounding the output shaft 18 can be seen. It is designed as a planet carrier shaft 16, which is supported relative to the housing 5 and here in particular relative to the part of the housing 5 designed as a housing cover 5.1 by means of a first bearing 17, which is also designed as a mitered ball bearing. The planet carrier 8 or its web 14 here rests against the first bearing 17 with an external support ring, which is respectively supported on the radial inside on a housing ring, which is part of the housing cover 5.1. The housing cover 5.1 thus forms the complete previously described housing 5 together with the housing base 5.2.

[0033] The planet carrier shaft 16 passes through a circular opening 20 of the housing 5 or the housing cover 5.1. A first oil channel 21 is arranged in the housing cover 5.1 and extends at least partially parallel to its wall. Figure 2 In the illustration of FIG. 5 , the first oil channel extends obliquely from the upper left to the lower right in the housing cover 5.1. The planet carrier shaft 16 has a swivel joint 25 in the area where the first oil channel 21 opens into the circular opening 20. The swivel joint is connected to a first hole 26, which is provided in the planet carrier shaft 16 parallel to the axis of rotation A. As indicated by the arrow, the lubricating oil can now flow through the first oil channel 21 and the swivel joint 25 into the first hole 26, and here Figure 2 In the illustration of , the oil widens to the left when viewed in the axial direction a. Through the radial channel 29 (i.e., the corresponding disk-shaped open area of ​​the planetary carrier shaft 16), the oil can now enter the area of ​​the rotation axis A. There, a nozzle 31 is provided in the area of ​​the planetary carrier shaft 16, which forms a connection from the first hole 26 to the second hole 32 area, and the second hole is designed as a central coaxial hole in the rotor shaft 4. From the relatively slowly rotating planetary carrier shaft 16 of the planetary gear carrier 8, the oil can now flow through the nozzle 31 into the second hole 32 of the rotor shaft 4 that rotates significantly faster, or be sprayed into it.

[0034] In addition to the nozzle 31, a retaining ring 37 is provided, which is arranged in the second hole and at least partially overlaps with the nozzle axially. The cooperation between the nozzle 31 and the retaining ring 37 can prevent the lubricating oil from leaking through the gap between the rotor shaft 4 and the planetary carrier shaft 16.

[0035] The retaining ring 37 advantageously has a disk portion 39 at its end facing the planet carrier shaft 16 , the disk portion extending radially inwards from the inner surface of the second hole 32 , wherein the disk portion 39 is completely covered by the nozzle 31 in the axial direction.

[0036] The retaining ring 37 advantageously has a cylindrical portion 38 which bears against the wall of the second bore 32 and is connected to a disk portion 39 .

[0037] The disk portion 39 advantageously has an opening on the radial inner side, which opening is advantageously designed to be circular, wherein the nozzle 31 has a second cylindrical portion 40 extending axially through the opening.

[0038] The second oil channel 22 now connects the second hole in the radial direction r to the outer surface of the rotor shaft 4 as viewed in the radial direction r. The lubricating oil can now flow out of the second oil channel 22 into the region of the rotor bearing 6 for the rotor shaft 4 and into the region of the sun gear 11 via the needle bearing 28. The oil can thus lubricate the rotor 3 of the electric machine 2 or its rotor bearing 6 on the one hand, and lubricate the second bearing 33 of the planetary gear carrier 8 arranged between the web support ring 15 and the housing ring 34 of the housing base 5.2 on the other hand. The residual oil is thrown out radially outward by centrifugal force and the rapidly rotating rotor shaft 4. In the region where the planetary gear pin 9 is designed as a hollow cylinder and is correspondingly closed on the web side by the plate 34 or the web 14 material, an oil baffle plate 36 is now provided, which is located on the web support ring side and is arranged so that the oil thrown out radially outward is correspondingly collected and fed into the hollow cylinder. Thus, a third radial oil channel 23 is provided in each individual planetary gear pin 9 designed as a hollow cylinder, which connects the inner cavity of the hollow cylinder radially outward to its outer surface. In this region, the two aforementioned splined ball bearings of the planetary gear bearing 27 are provided, so that the bearing of the planetary gear 10 is lubricated by means of the lubricating oil flowing through the third oil channel 23 .

[0039] Finally, under the action of the centrifugal force generated in the housing base 5.2 or the housing 5, the oil Figure 1 The diagram always flows further outward, Figure 2In the illustration, the oil flows upwards, in particular, and flows downwards in the not shown area below the axis of rotation A. As a result, a fourth oil passage 24 can be optionally provided, through which the remaining oil can be discharged to the outside of the housing 5. As a result, it can be returned to the circuit after cleaning, for example, and sent back to the electric drive 1 through the first oil passage 21, thus flowing through the aforementioned route again. This allows both the planetary gear stage 13 and the electric motor 2 to be well lubricated.

[0040] Reference numerals list

[0041] 1 Electric drive system

[0042] 2 Motor

[0043] 3 Rotor

[0044] 4 Rotor shaft

[0045] 5 Housing

[0046] 5.1 Housing cover

[0047] 5.2 Shell base

[0048] 6 Rotor bearing

[0049] 7 Output Devices

[0050] 8 Planetary gear carrier

[0051] 9 Planetary gear pin

[0052] 10 Planetary gear

[0053] 11 Sun gear

[0054] 12 Ring gear

[0055] 13 planetary gear stages

[0056] 14 belly plate

[0057] 15 Web support ring

[0058] 16 Planet carrier shaft

[0059] 17 First bearing

[0060] 18 Output shaft

[0061] 19 Spline shaft teeth

[0062] 20 Round opening

[0063] 21 First oil channel

[0064] 22 Second oil channel

[0065] 23 Third oil channel

[0066] 24 Fourth oil channel

[0067] 25 Swivel joint

[0068] 26 First Hole

[0069] 27 Planetary gear support device

[0070] 28 Needle roller bearing

[0071] 29 Radial channel

[0072] 30 Stator

[0073] 31 Nozzle

[0074] 32 Second hole

[0075] 33 Second bearing

[0076] 34 Shell ring

[0077] 35 Plate

[0078] 36 Oil baffle

[0079] 37 Retaining ring

[0080] 38 Cylindrical part

[0081] 39 Panbu

[0082] 40 second cylindrical portion

[0083] A Rotation axis

[0084] a Axial

[0085] r Radial.

Claims

1. An electric drive system (1) for a motor vehicle, comprising: an electric motor (2) having a rotor (3) having a rotor shaft (4); a planetary gear stage (13) having a sun gear (11), a planetary gear carrier (8) and corresponding planetary gears (10) and a ring gear (12); wherein: The rotor shaft (4) is connected or can be connected to the sun gear (11) in a torque-transmitting manner, wherein the planetary gear carrier (8) has a planetary carrier shaft (16), which is arranged coaxially with the rotor shaft (4) and axially adjacent to the rotor shaft, wherein the planetary carrier shaft (16) is supported relative to the housing (5) by means of a first bearing (17), wherein the housing (5) has a circular opening (20) for the planetary carrier shaft (16) to pass through, wherein the housing (5) has a circular opening (20) for the planetary carrier shaft (16) to pass through, and wherein the housing (5) has a circular opening (20) for the planetary carrier shaft (16) to pass through. The invention relates to a first oil passage (21) of a shaped opening (20), and the planet carrier shaft (16) has a swivel joint (25) in the axial region of the opening (20) with respect to its rotation axis (A), wherein the planet carrier shaft (16) has at least one first hole (26) extending in the axial direction (a), the first hole being connected to the swivel joint (25) at one end thereof, wherein the rotor shaft (4) has a second hole (32) extending in the axial direction, and wherein the first hole (26) is connected to the second hole (32), A nozzle (31) opening into the second hole (32) is arranged on the end side of the planet carrier shaft (16) facing the rotor shaft (4). It is characterized in that A retaining ring (37) is provided, which is arranged within the second hole (32) so as to at least partially overlap the nozzle (31) axially.

2. The electric drive system (1) according to claim 1, It is characterized in that The retaining ring (37) has a disk portion (39) at its end facing the planet carrier shaft (16) and extending radially inward from the inner surface of the second hole, wherein the disk portion (39) is completely covered by the nozzle (31) in the axial direction.

3. The electric drive system (1) according to claim 1 or 2, It is characterized in that The sun gear (11) is arranged in a region axially adjacent to the nozzle (31).

4. The electric drive system (1) according to any one of the preceding claims, It is characterized in that The first hole (26) is arranged parallel to the rotation axis (a) of the planet carrier shaft (16).

5. The electric drive system (1) according to any one of the preceding claims, It is characterized in that The rotor shaft (4) has at least one second oil passage (22) connecting the radial outer surface of the rotor shaft (4) to the second hole (32).

6. Electric drive system (1) according to any one of the preceding claims, It is characterized in that The planetary gear (10) is arranged coaxially with the planetary gear pin (9), wherein an oil baffle plate (36) is arranged on the planetary gear pin (9) so that oil thrown radially outward from the rotor shaft (4) is introduced into the planetary gear pin (9) designed as a hollow cylinder.

7. The electric drive system (1) according to claim 5 and 6, It is characterized in that The planetary gear pin (9) has a third oil passage (23), which connects the inner cavity of the hollow cylinder to the outer surface of the planetary gear pin (9) that carries the planetary gear (10).

8. The electric drive system (1) according to claim 7, It is characterized in that At least one fourth oil passage (24) is arranged in the housing (5) radially outside the ring gear (12) and overlaps with the ring gear in the axial direction.

9. The electric drive system (1) according to claim 8, It is characterized in that At least one of the second oil passage (22), the third oil passage (23), and the fourth oil passage (24) extends in a radial direction (r).

10. The electric drive system (1) according to any one of the preceding claims, It is characterized in that The housing (5) has a housing base (5.2) and a housing cover (5.1), wherein the first oil channel (21) is arranged in a wall of the housing cover (5.1), and wherein the first oil channel (21) extends at least partially parallel to an outer surface of the wall.

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