Transmission device having exchangeable sliding contact unit, electric drive unit

Abstract

The invention relates to a transmission device (1) for an electric drive unit (2), having a housing (3) in which an input shaft (4) of a transmission unit is positioned, wherein the input shaft (4) can be connected to a rotor shaft (5) of an electric machine (6), and having an earthing device (7) which has a part (8) supported on the input side, a part (9) supported in a manner fixed to the housing and a sliding contact (10) positioned at least in sections between these two parts (8, 9) and electrically conductively coupled with these two parts (8, 9), wherein the part (9) supported in a manner fixed to the housing is attached to the housing in a non-destructively releasable manner from the outside. The invention also relates to an electric drive unit (2) having an electric machine and a transmission device (1), wherein an input shaft (4) of the transmission device (1) is connected in a torque-transmitting manner to a rotor shaft (5) of a rotor of the electric machine (6).

Description

[0001] Gear device with replaceable sliding contact unit, electric drive unit

[0002] The invention relates to a transmission device for an electric drive unit, comprising a housing in which an input shaft of a transmission unit is positioned, wherein the input shaft is connectable to a rotor shaft of an electric machine, and comprising a grounding device having a part supported on the input shaft side, a part fixed to the housing, and a sliding contact unit positioned at least in sections between these two parts and electrically conductively coupled to these two parts.

[0003] DE 10 2019 133 677 A1 discloses an electric drive unit comprising an electric machine with a rotor, a rotor shaft, and a stator, and a housing associated with the electric machine, as well as a lance arranged within the rotor shaft and electrically conductively connected to the rotor shaft. The lance is supported on the rotor shaft and mounted in a floating manner on the housing. The lance and the housing are electrically conductively coupled to one another via at least one resilient, electrically conductive connecting element. The lance and the connecting element provide a grounding function.

[0004] A grounding element is designed to reduce induced voltages / potential differences in the mechanical components of an electric drive unit, as these would otherwise discharge through conductive components such as bearings or gearing components, causing damage. The sliding contacts used in this case are typically subject to abrasive loads and thus wear over time. Spring-loaded systems are known in the art that allow adjustment of the sliding contact. However, adjustment is limited until the sliding contact is completely worn. The object of the present invention is to provide a transmission device that offers simpler maintenance and reduced assembly effort.

[0005] This is solved in a generic gear device in that the part fixed to the housing is attached to the housing from the outside in a non-destructive manner and can be re-detachably mounted.

[0006] This ensures that the sliding contact unit can be removed and replaced from outside the housing. The input shaft is preferably hollow and allows for the positioning of the part supported on the input shaft side as well as the sliding contact unit. The gear unit can be a planetary gear unit or a spur gear unit.

[0007] Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

[0008] It is advantageous if the part fixed to the housing is positioned in a passage / through hole of the housing and seals the housing from the environment. This ensures that no fluid can flow outwards / into the environment. Preferably, the part fixed to the housing extends at least partially into the interior of the housing. Particularly preferably, the part fixed to the housing extends at least partially axially into the input shaft, which is designed as a hollow shaft. This ensures optimal use of the installation space.

[0009] It is advantageous if the part supported in a manner fixed to the housing has two radial openings that are axially spaced from one another and fluidically connected to one another. Preferably, a plurality of these openings are evenly distributed in the circumferential direction on a lateral surface of the part supported in a manner fixed to the housing. Particularly preferably, the part supported in a manner fixed to the housing is tubular (hollow) at least in sections, wherein the sections can have different outer diameters. This enables a flexible design of the part supported in a manner fixed to the housing. It is expedient if a first opening is arranged on the inside of the input shaft and a second opening is arranged in the passage of the housing. The first opening is preferably larger, i.e., it has a larger cross-section, than the second opening. Overall, a channel is formed that allows a fluid to flow through into the input shaft.The channel extends from the first opening through the part fixed to the housing to the second opening, and the fluid can flow through the second opening on the inside of the input shaft. This ensures a distribution of fluid, preferably coolant, throughout the input shaft.

[0010] Furthermore, the part fixed to the housing can have a hole, preferably a blind hole, on one axial end side that accommodates the sliding contact unit. This connects the sliding contact unit to the part fixed to the housing and facilitates replacement of the sliding contact unit. The blind hole preferably extends from the end side to a starting side formed by a head section of the part fixed to the housing, so that in the axial direction, the head section forms the bottom or, in the axial direction, a boundary of the blind hole.

[0011] Preferably, the part fixed to the housing has a threaded section by which it is secured to the housing. This allows the part fixed to the housing to be screwed into the housing. This allows for easy removal of the part and simplifies the replacement of the sliding contact unit.

[0012] It is advantageous if at least one seal is present that seals the housing interior from the environment / from an area on the outside of the housing. The area on the outside of the housing refers to everything outside the housing. This prevents uncontrolled flow of the fluid, and the fluid can only flow in through the previously described channel, which is defined between the first and second openings, on the inside of the input shaft.

[0013] It is expedient if a first seal is a radial seal and a second seal is an axial seal. The first seal seals between an inner surface of the passage and a section, a sealing section, of the part supported fixedly to the housing. The second seal seals between the head section and an outer side of the housing, in this case an outer support surface for the head section, so that no fluid escapes outside the housing. The first seal and the second seal are preferably axially spaced from one another, whereby an area is formed between the seals in which the fluid can collect before it flows on through the first opening. Particularly preferably, the sealing section with the radial seal is positioned axially between the first opening and the second opening. This ensures that the fluid then flows through the first opening.

[0014] The invention also relates to an electric drive unit with an electric machine and a transmission device, wherein an input shaft of the transmission device is connected to a rotor shaft of a rotor of the electric machine in a torque-transmitting manner.

[0015] An advantageous embodiment of the invention is explained in more detail below with reference to a drawing with figures.

[0016] They show:

[0017] Fig. 1 shows a section of a transmission device according to the invention in a sectional view,

[0018] Fig. 2 shows a housing-fixed part of the transmission device in a perspective view, and

[0019] Fig. 3 is a schematic representation of an electric drive unit comprising the transmission device.

[0020] The figures are merely schematic in nature and serve exclusively to understand the invention. The same elements are provided with the same reference numerals. Fig. 1 shows a section of a transmission device 1 according to the invention for an electric drive unit 2 in a sectional view, with a housing 3 in which an input shaft 4 of a transmission unit is positioned, wherein the input shaft 4 is connectable to a rotor shaft 5 of an electric machine 6, and with a grounding device 7 with a part 8 supported on the input shaft side, a part 9 supported fixedly to the housing and a sliding contact unit 10 positioned at least in sections between these two parts 8, 9 and electrically conductively coupled to these two parts 8, 9. It should be emphasized that the part 9 supported fixedly to the housing is attached to the housing 3 from the outside so that it can be detachably removed without causing any damage.In the present embodiment, the gear unit is a planetary gear unit and the input shaft 4 is a sun shaft.

[0021] To better clarify the structure, an axial direction 11, a radial direction 12, and a circumferential direction 13 are defined. The axial direction 11 describes the direction along a central axis 14 or rotational axis of the input shaft 4, the circumferential direction 13 describes the direction of rotation of the input shaft 4, and the radial direction 12 describes the direction perpendicular to the axial direction 11.

[0022] The input shaft 4 is positioned in the housing 3, more precisely within a planet gear carrier 15 of the planetary gear unit, and extends in the axial direction 11. The input shaft 4 is designed as a hollow shaft and has various sections with different outer diameters and inner diameters in the axial direction 11. At a first section, the input shaft 4 has a receptacle 16 for connection to the rotor shaft 5 (not shown here) with an outer diameter. The first section merges conically into a second section, which has a second outer diameter that is smaller than the outer diameter of the first section. This section extends in the axial direction 11 and merges into a third section, a toothed section with external teeth 17, which forms a sun gear 18.In the axial direction 11, a fourth section is formed with an outer diameter which is smaller than the outer diameter of the second section, on which a bearing 19 for supporting the input shaft 4 on the plate wheel carrier 15 is positioned.

[0023] The hollow part of the input shaft 4 has a first section on an inner circumferential surface with a toothing 20 to accommodate the rotor shaft 5 and to be connected in a torque-transmitting manner. According to the previously described conical transition from the first section to the second section on the outside of the input shaft 4, the hollow part has a second section with an inner diameter, wherein the second section extends in the axial direction 11. A third section, which adjoins the second section in the axial direction 11, has an inner diameter that is smaller than the inner diameter of the second section.

[0024] The part 8 supported on the input shaft side is positioned in the axial direction 11 radially inside the input shaft 4 in the hollow part in the second section. The part 8 supported on the input shaft side is a tubular component with two sections, a first section with a first outer diameter and a first inner diameter and a second section with a second outer diameter and a second inner diameter. The outer diameter and the inner diameter of the first section are larger than the outer diameter and the inner diameter of the second section. In the axial direction 11, it has an opening 21 at the end of the second section for holding the sliding contact unit 10. The part 8 supported on the input shaft side is supported by the first section on the inner circumferential surface of the second section.

[0025] The sliding contact unit 10 is held in the axial direction 11 in the part 8 supported on the input shaft side and extends in the axial direction 11, so that a part of the sliding contact unit 10 is held in the part 9 supported fixedly on the housing. The sliding contact unit 10 is formed in the present case from a carbon brush holder 22 in which a carbon pin 23 is held in the axial direction 11.

[0026] The housing-fixed part 9 is cylindrical with a hole 24, in this case a blind hole, extending in the axial direction 11 and an adjoining head section 25, thus being hollow in the axial direction 11 up to the head section 25. The cylindrical part is divided into sections on the outside. The sections sometimes have different outer diameters. The inner diameter of the cylindrical part, hence the diameter of the blind hole, is constant in the axial direction 11. The outer diameter of the head section 25 is larger than the outer diameters of the individual sections of the cylindrical part.

[0027] The part 9, which is fixedly supported on the housing, has a depression 26 running in the axial direction 11 in order to better accommodate the sliding contact unit 10. The cylindrical part has a total of five sections. The first section and the second section have an outer diameter of the same size, wherein the two sections are separated by a notch 27 running in the circumferential direction 13, which is thus arranged between the first and second sections in the axial direction 11. On the first section, on the side oriented towards the notch 27, at the end of the first section, first openings 28, in this case through-bores, are distributed in the circumferential direction 13. The first openings 28 are positioned evenly distributed relative to one another in the circumferential direction 13. The sliding contact unit 10 is inserted into the hole 24 such that the axial end of the sliding contact unit 10 borders the first openings 28.

[0028] A third section then adjoins the second section, with the third section having a larger outer diameter than the second section. An external thread 29 is formed on the third section, a threaded section 41, with which the part 9, which is fixedly supported on the housing, is detachably attached to the housing 3. The transition from the second section to the third section is conical.

[0029] In the axial direction 11, a fourth section, a sealing section, borders the third section and has a larger outer diameter than that of the third section. A first seal 30, in this case a radial seal, is formed on this section. A sealing ring 31 extending in the circumferential direction 13 is positioned in a notch 32 on the fourth section that extends in the circumferential direction 13. A fifth section borders the fourth section and has an outer diameter that is larger than the outer diameter of the third section but smaller than that of the fourth section. The fifth section extends in the axial direction 11 as far as the head section 25. The second opening 33 is provided in the fifth section. In the present embodiment, a plurality of second openings 33, in this case through-bores, are provided in the circumferential direction 13. The second openings 33 are positioned and evenly distributed relative to one another in the circumferential direction 13.The second openings 33 have a larger diameter than those of the first openings 28. On the underside of the head section 25, the side facing the housing 3 in the axial direction 11, a second seal 34, an axial seal in the form of a sealing lip 35, is arranged. A washer 37 is positioned radially outside this sealing lip 35, by means of which the remaining underside, i.e., the side not covered by the sealing lip 35, is supported on the housing 3. The second openings 33 are positioned, as shown, between the first seal 30 and the second seal 33.

[0030] The housing 3 has a passage / through-hole 38 in which the part 9 supported fixedly to the housing is detachably fastened. The passage 38 is divided into two sections in the axial direction 11: a first section for fastening the part 9 supported fixedly to the housing, and a second section for sealing and as a passage area for the fluid. The first section has an internal thread 39 which is matched to the external thread 29 of the part 9 supported fixedly to the housing. The second section, which has a larger internal diameter than the first section, has an opening 40 on its inner surface, from which the fluid can flow into the second section. This opening 40 is positioned at the same height as the second openings 33 in the axial direction 11.

[0031] The first seal 30 now seals between the inner circumferential surface of the second section of the passage 38 and the sealing section of the part 9 supported fixedly to the housing. The second seal 34 seals in the axial direction 11 between the housing 3 and the head section 25, so that no fluid can escape into an environment 36. Reference is made below to Fig. 2. The part 9 supported fixedly to the housing is shown in Fig. 2 in a single perspective, in a perspective view.

[0032] Overall, the present embodiment provides a grounding function in which the current is transmitted via the input shaft 4 to the housing 3 via the individual parts of the grounding device 7, the part 8 supported on the input shaft side, the sliding contact unit 10, and the part 10 supported on the housing. Furthermore, cooling of the input shaft 4 is provided, which is achieved by the first openings 28 and second openings 33 provided in the part 9 supported on the housing, allowing the fluid to flow into the input shaft. The external thread 29 on the part 9 supported on the housing allows for loosening, which allows the sliding contact unit 10 to be replaced when it becomes worn.

[0033] Fig. 3 shows a schematic view of the electric drive unit 2, in which the transmission device 1 according to Fig. 1 is shown as a black box in order to illustrate the connection to the other components of the electric drive unit 2.

[0034] The electric drive unit 2 is formed in the present case from the transmission device 1 and the electric machine 6, wherein the electric machine 6 is connected to the input shaft 4 of the transmission device 1 via the rotor shaft 5 in a torque-transmitting manner.

[0035] List of reference symbols

[0036] Gearbox device electric drive unit

[0037] Housing

[0038] input shaft

[0039] rotor shaft electric machine

[0040] Earthing device input shaft supported part housing fixed supported part

[0041] Sliding contact unit axial direction radial direction circumferential direction

[0042] central axis

[0043] planet gear carrier

[0044] Recording

[0045] external gearing

[0046] sun gear

[0047] warehouse

[0048] Gearing

[0049] opening

[0050] Carbon brush holder

[0051] charcoal pencil

[0052] Hole

[0053] Head section

[0054] depression

[0055] Notch first opening external thread first seal

[0056] Sealing ring notch second opening second sealing ring sealing lip surroundings washer passage / through hole internal thread opening threaded section

Claims

Patent claims 1. A transmission device (1) for an electric drive unit (2), comprising a housing (3) in which an input shaft (4) of a transmission unit is positioned, the input shaft (4) being connectable to a rotor shaft (5) of an electric machine (6), and comprising an earthing device (7) having a part (8) supported on the input shaft side, a part (9) supported fixedly to the housing, and a sliding contact unit (10) positioned at least in sections between these two parts (8, 9) and electrically conductively coupled to these two parts (8, 9), characterized in that the part (9) supported fixedly to the housing is attached to the housing (3) from the outside in a non-destructive manner so that it can be redetached.

2. Transmission device (1) according to claim 1, characterized in that the part (9) supported fixedly to the housing is positioned in a passage (38) of the housing (3) and seals the housing (3) from the environment (36).

3. Transmission device (1) according to claim 1 or 2, characterized in that the part (9) supported fixedly to the housing has two radial openings (28, 33) which are axially spaced from one another and fluidically connected to one another.

4. Transmission device (1) according to claim 3, characterized in that a first opening (28) is arranged on the inside of the input shaft and a second opening (33) is arranged in the passage (38) of the housing (3).

5. Gear device (1) according to one of the preceding claims, characterized in that the part (9) supported fixedly to the housing has a hole (24) receiving the sliding contact unit (10) on one axial end side.

6. Transmission device (1) according to one of the preceding claims, characterized in that the part (9) supported fixedly to the housing has a threaded section (41) by means of which it is fixed to the housing (3).

7. Transmission device (1) according to one of the preceding claims, characterized in that at least one seal (30, 34) is present which seals a housing interior from the environment (36).

8. Transmission device (1) according to claim 7, characterized in that a first seal (30) is a radial seal and a second seal (33) is an axial seal.

9. Transmission device (1) according to claim 8, characterized in that the first seal (30) and the second seal (33) are axially spaced from one another.

10. Electric drive unit (2) with an electric machine and a transmission device (1), wherein an input shaft (4) of the transmission device (1) is connected to a rotor shaft (5) of a rotor of the electric machine (6) in a torque-transmitting manner.

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