Drive unit for a vehicle and a vehicle with the drive unit

Abstract

The invention relates to a drive unit (1) for a vehicle, comprising an inverter (2) having an inverter housing (3), an electric motor (4) having a motor housing (5) arranged adjacent to the inverter housing, and a transmission (6) having a transmission housing (7) arranged adjacent to the motor housing (5). The drive unit (1) includes at least one fastening element (9) which is guided through the housings (3, 5, 7) to fasten the three housings (3, 5, 7) to one another, and seals (10) which are arranged between the adjacent housings (3, 5, 7). Electrical contacts (11, 12) are also provided, each electrically connecting two adjacent housings (3, 5, 7). The invention further relates to a vehicle with the drive unit (1) according to the invention.

Description

[0001] The invention relates to a drive unit for a vehicle comprising an inverter having an inverter housing, an electric motor having a motor housing, and a transmission having a transmission housing. Furthermore, the drive unit comprises at least one fastening element for fastening the three housings to one another in the above-specified order, which fastening element is guided through the housings, and seals arranged between adjacent housings. Furthermore, the invention relates to a vehicle comprising the drive unit according to the invention.

[0002] Due to the increasing complexity in the development of components for optimizing drive trains in electric vehicles, a type of sandwich construction is being created for the rear axles for reasons of installation space, with the inverter in the middle and the two gearboxes and their electric motors attached to the left and right of the inverter.

[0003] For the joint assembly of the components across three housings per side, a type of triple flange is ultimately created. The electric motor housing is clamped between the inverter housing and the gearbox housing. However, for reasons of electromagnetic compatibility (EMC), the development team specifies that all housings be conductively connected to form a single unit in order to reduce or eliminate EMC interference.

[0004] For this reason, a conductive metal bead gasket is used as the flange seal between the individual housings. This is easy to replace during service and offers good electrical conductivity, but is also significantly more expensive than a liquid gasket.

[0005] In addition, recent salt spray tests revealed inadequate sealing of the gearbox interior against the environment. The seal was infiltrated by the aggressive and highly corrosive medium, leading to long-term drive failure. This would require additional measures such as applying a sealing layer of grease to the exterior, which, however, entails additional effort and increased costs and can also be washed out over the product's lifetime.

[0006] In contrast, a flexible liquid gasket can be used, which is both cost-effective and provides excellent and reliable external sealing. The disadvantage, however, is the insulating effect of the liquid gasket and the resulting continued EMC interference.

[0007] DE 10 2019 124 231 A1 shows an electric drive device, comprising a machine unit with a machine housing and at least one electric rotary machine arranged therein, and comprising power electronics with an electronics housing and control electronics arranged therein, wherein at least one of the two housings has at least one projection for the purpose of defined positioning of the machine unit and the power electronics to one another during and / or after assembly and the respective other housing has a recess complementary in shape and size for receiving the projection, wherein the material forming the projection and the recess is electrically conductive at least in sections and the projection and the recess are electrically conductively connected to an earth for the purpose of earthing the power electronics or the machine unit.

[0008] DE 10 2018 108 056 A1 shows an actuator, in particular for a drive train of a motor vehicle, comprising a drive unit with an electronic module and an electric motor accommodated in an engine pot, as well as a transmission driven in rotation by the electric motor, and a screw connection connecting a housing of the drive unit and a transmission housing of the transmission.

[0009] DE 197 32 038 A1 shows a motor-driven unit for a motor vehicle brake system with a hydraulic housing, a closed housing for an electronics unit arranged on one side and with a drive unit which is arranged on another, opposite side, wherein the housing and the drive unit are firmly connected to the hydraulic housing, wherein at least one fastening means is provided which extends from the housing to the drive unit, fastens it to the hydraulic housing with the same contact pressure and at the same time electrically connects the drive unit to a busbar in the area of ​​the electronics unit.

[0010] It is therefore an object of the invention to improve the drive unit.

[0011] This object is achieved by the subject matter having the features according to the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0012] A drive unit for a vehicle according to the invention has an inverter, an electric motor, and a transmission, wherein these three components are arranged in a sandwich construction. The electric motor is arranged centrally between the inverter and the transmission. The inverter, the electric motor, and the transmission each have their own housing. Furthermore, the three individual housings each comprise at least one bore / through opening / recess, which are arranged axially aligned with one another. The bores / through holes / recesses can be designed as through holes or as blind holes or threaded holes. Within this at least one bore / through opening / recess of the three housings, at least one fastening element for fastening the three housings to one another is arranged. A seal is arranged between two adjacent housings.According to the invention, electrical contact is made between two adjacent housings to reduce EMC interference.

[0013] The advantage of the present invention is that the use of a seal between adjacent housings provides a seal against liquids and environmental influences, as well as a reduction in mechanical vibrations. At the same time, the use of electrical contact between two adjacent housings can reduce EMC interference. This provides a drive unit that not only reduces installation space and is cost-effective to manufacture, but also shields against EMC interference.

[0014] According to the invention, the electrical contacts can preferably be designed as an external electrical contact and an internal electrical contact of two adjacent housings. The external electrical contact can be arranged on the outside of two adjacent housings, and the internal electrical contact can be arranged within two adjacent housings. The at least one electrical contact serves to divert EMC interference, preventing voltage or current peaks from discharging through sensitive components of the inverter, electric motor, or transmission, which could ultimately lead to the failure of the entire drive unit.

[0015] According to the invention, an external electrical contact is designed as a terminal or clamp, which can be arranged on a flange coupling between two adjacent housings. This means that the terminal or clamp engages around the joined flanges protruding outward from the adjacent housings. A terminal or clamp is easy to manufacture and install, allowing the insulating seal between two adjacent housings to be electrically bridged. Furthermore, a terminal or clamp can also be retrofitted to existing arrangements.

[0016] The seals between two adjacent housings can preferably be designed as liquid seals. A liquid seal is applied in liquid form at room temperature. A distinction is made between polycondensation adhesives, such as silicone, and solvent- or water-based liquid seals. This offers the advantage that they can be used in complex components that require sealing. Furthermore, the use of liquid seals results in the advantage of providing optimal protection against penetrating media, especially corrosive media. Furthermore, the application of liquid seals is inexpensive and easy to implement.

[0017] The electrical contact can preferably be made of an electrically conductive material, such as aluminum, silver, copper, iron, or stainless steel. This provides optimal shielding of the inverter, electric motor, and gearbox against EMC interference.

[0018] In another embodiment, the internal electrical contact can preferably be designed as an elastic element, in particular as a spring, which can be arranged in the respectively adjacent housings. Opposing blind holes can be formed in the housings for this purpose. One or both blind holes for receiving the spring can also extend into a flange adjacent to the housing. The spring can be designed as a compression spring or as a spring plate and made of an electrically conductive material, thus reducing EMC interference. The use of springs is not only cost-effective, but also easy to implement. By using the elastic element, in particular the spring, a pressurized arrangement of the housings relative to one another is achieved across the entire drive unit.

[0019] Preferably, the housings can be secured to one another by a single fastening element. This allows for a simpler construction and easier attachment of the housings to one another.

[0020] The fastening element can preferably be designed as a bolt or screw, in particular as a flange screw. This ensures an axially fixed attachment of the inverter housing, the motor housing, and the gearbox housing to one another.

[0021] Preferably, the at least one fastening element can be guided through at least one of the housings in such a way that its periphery rests against the housing at least partially, particularly preferably completely. For example, the diameter of the at least one bore in the inverter housing and the gear housing can each correspond to the diameter of the fastening element. A play-free mounting of the fastening element within the bores can thus be realized.

[0022] Preferably, the at least one fastening element can be guided with play through at least one of the housings, thereby forming an insulating air gap. For example, the diameter of the at least one bore in the motor housing can be larger than the diameter of the fastening element. This allows an air gap to be created between the fastening element and the inner circumference of the motor housing, which has an insulating effect. The thus insulated motor housing must be reconnected to form a common unit with the other two housings by electrical contact via a terminal or compression spring.

[0023] Furthermore, the invention relates to a vehicle having a drive unit according to one of the above-mentioned features.

[0024] The invention is explained in more detail below with reference to the figures: Fig. 1 shows a first embodiment of a drive unit according to the invention; and Fig. 2 shows a second embodiment of a drive unit according to the invention.

[0025] The figures are merely schematic and serve solely to clarify the invention. The same elements are designated by the same reference numerals.

[0026] Fig. 1 shows a first embodiment of a drive unit 1 according to the invention. The drive unit 1 has an inverter 2 with an inverter housing 3. A motor housing 5 of an electric motor 4 is arranged adjacent to the inverter housing 3. On the other side, adjacent to the motor housing 5, a gear housing 7 of a gear 6 is arranged. The inverter housing 3, motor housing 5, and gear housing 7 have a common axial alignment, thereby creating a sandwich-like design of the drive unit 1. In order to be able to connect the three housings 3, 5, 7 to one another, the three housings 3, 5, 7 each have a bore / through opening / recess 8, which are arranged axially aligned with one another. Within these bores 8, a single fastening element 9 is arranged, which connects the three housings 3, 5, 7 to one another. This means that the housings 3, 5, 7 are attached to each other.The fastening element 9 can be designed as a screw, in particular a flange screw. Alternatively, the fastening element 9 can also be designed as a bolt. Alternatively, the three housings 3, 5, 7 can also be connected to one another by several fastening elements 9, each of which has its own bore / through opening / recess 8 in the respective housings 3, 5, 7. The fastening element 9 can have a widened head, which can be arranged in a countersunk hole / recess in the gear housing 7. Furthermore, the bore / through opening / recess 8 on the inverter housing 3 can be designed as a blind hole in which one end of the fastening element 9 is fixed. If the fastening element 8 is designed as a screw, a thread into which the screw can be screwed can be introduced into the blind hole in the inverter housing 3.

[0027] The bores 8 of the inverter housing 3 and the gearbox housing 7 correspond to the diameter of the fastening element 9, so that the fastening element 9 is mounted without play within the bores 8 of the inverter housing 3 and the gearbox housing 7. The diameter of the bore 8 in the motor housing 5 is larger than the diameter of the fastening element 9, so that an air gap 15, which has an insulating effect, remains between the inner circumference of the motor housing 5 and the fastening element 9.

[0028] Furthermore, a seal 10 is arranged between each of two adjacent housings 3, 5, and 7. More specifically, a seal 10 is arranged between the inverter housing 3 and the adjacent motor housing 5, and between the other end of the motor housing 5 and the adjacent gearbox housing 7. The seal 10 is designed as a liquid seal, which provides optimal sealing while also providing an insulating effect.

[0029] The inverter housing 3 and the gearbox housing 7 each have a flange 13 on their sides facing the motor housing 5. The motor housing 5 has a flange 13 at each end. The flanges 13 are arranged on the radial outer circumference at the ends of the housings 3, 7 facing the motor housing 5 and each form a flange coupling with a flange 13 of the motor housing 5. The flanges 13 of the two adjacent housings 3 and 5, as well as the flanges 13 of the two adjacent housings 5 ​​and 7, are also spaced apart by the seal 10.

[0030] On the outer circumference of the adjacent flanges 13, i.e. of the flange coupling, an external electrical contact 11 is arranged in each case, which can be made of an electrically conductive material, such as aluminum, copper, iron, stainless steel or silver. The external electrical contact 11 can be designed as a clamp or clip, so that it contactingly encompasses or grips the flange coupling formed by the flanges 13. Preferably, the clamp or clip can fully contact the flanges 13 or the flange coupling on the side and end surfaces. The arrangement of the external electrical contact 11 dissipates EMC interference, so that the drive unit 1 is shielded from EMC interference. The clip 11 offers the advantage that it can be retrofitted to existing drive units 1.

[0031] Fig. 2 shows a second embodiment of a drive unit 1 according to the invention. The drive unit 1 in Fig.2 is essentially identical in construction to the first embodiment, but differs in the arrangement and design of the electrical contact 12. The second embodiment of the drive unit 1 has flanges 14 on the three housings 3, 5 and 7. The flanges 14 are arranged axially aligned with one another. An internal electrical contact 12 is arranged between the adjacent housings 3 and 5 and the adjacent housings 5 ​​and 7. The internal electrical contact 12 is arranged in opposite blind holes in the housings 3 and 5 and the housings 5 ​​and 7. The blind hole can be located within the housing 3, 5 and 7 or can extend partially or completely into the flange 14 in at least one of the housings 3, 5, 7 (e.g. in the housing 3). This internal electrical contact 12 can be designed as a spring, in particular a compression spring or a spring plate.Since the spring is made of an electrically conductive material, the drive unit 1 is shielded from EMC interference.

[0032] It is also conceivable to combine the two embodiments and to provide both an external electrical contact 11 and an internal electrical contact 12 between the housings 3 and 5 or the housings 5 ​​and 7, so that the EMC interference reduction can be achieved. List of reference symbols 1 drive unit 2 inverters 3 inverter housings 4 electric motor 5 Motor housing 6 gearboxes 7 Gearbox housing 8 Hole / through hole / recess 9 Fastening element 10 Seal 11 External electrical contact 12 Internal electrical contact 13 Flange 14 Flange 15 Air gap

Claims

[1] Drive unit (1) for a vehicle, comprising: an inverter (2) having an inverter housing (3), an electric motor (4) having a motor housing (5) arranged adjacent to the inverter housing, a gearbox (6) having a gearbox housing (7) arranged adjacent to the motor housing (5), at least one fastening element (9) which is guided through the housings (3, 5, 7) in order to fasten the three housings (3, 5, 7) to one another, and Seals (10) arranged between the adjacent housings (3, 5, 7), characterized by electrical contacts (11, 12) which each electrically connect two adjacent housings (3, 5, 7), wherein the electrical contacts are designed as an outer electrical contact (11) and an inner electrical contact (12) of two adjacent housings (3, 5, 7) and the outer electrical contact (11) is designed as a terminal or clamp which is arranged on a flange coupling which is formed by flanges (13) of the adjacent housings (3, 5, 7). [2] Drive unit (1) according to claim 1, characterized by that the seals (10) are designed as liquid seals. [3] Drive unit (1) according to one of claims 1 or 2, characterized by that the inner electrical contact (12) is designed as an elastic element, in particular as a spring, which is arranged in a flange (14) or an inner region of the adjacent housings (3, 5, 6). [4] Drive unit (1) according to one of claims 1 to 3, characterized by that the housings (3, 5, 7) are fastened to one another by a single fastening element (9). [5] Drive unit (1) according to one of claims 1 to 4, characterized by that the fastening element (9) is designed as a bolt or screw. [6] Drive unit (1) according to one of claims 1 to 5, characterized by that the fastening element (9) is guided through at least one of the housings (3, 5, 7) without play, so that it rests on the housing (3, 5, 7) at least in sections, preferably completely, at its circumference. [7] Drive unit (1) according to one of claims 1 to 6, characterized by that the fastening element (9) is guided with play through at least one of the housings (3, 5, 7) in order to form an air gap (15). [8] Vehicle comprising a drive unit (1) according to one of claims 1 to 7.

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