Electric drive for a vehicle and corresponding manufacturing method

Abstract

Electric drive (1) for a vehicle (100), the electric drive (1) comprising: – a rotating electric machine (2); – a cover element (3) with an outer side (4) and an inner side (5) opposing the outer side (4); – a housing (6) forming an accommodation space (7), which is limited by a wall (15) of the housing (6) and the inner side (5) of the cover element (3), the inner side (5) of the cover element (3) being situated upon a contact face (16) formed by the wall (15); and – an electrical component (9) being disposed inside the accommodation space; wherein the cover element is fastened to the wall (15) for closing the accommodation space (7) with regard to the exterior (E) of the electric drive (1) by means of at least one crimp joint (20).

Description

[0001] Electric drive for a vehicle and corresponding manufacturing method

[0002] The present invention relates to an electric drive for a vehicle, the electric drive comprising: a rotating electric machine; a cover element with an outer side and an inner side opposing the outer side; a housing forming an accommodation space, which is limited by a wall of the housing and the inner side of the cover element, the inner side of the cover element being situated upon a contact face formed by the wall; and an electrical component being disposed inside the accommodation space.

[0003] Aside, the invention relates to a method for manufacturing an electric drive for a vehicle.

[0004] It is commonly known to form an accommodation space for an electrical component in a housing of an electric drive and to close this accommodation space by means of a cover element.

[0005] Exemplarily, US 2020 / 0381977 A1 discloses a drive device for an electrically drivable vehicle. The drive device comprises an electric machine and a housing body with a housing portion for the electric machine and another housing portion for a connection device. The other housing portion is closed by a cover fastened to a wall of the other housing portion.

[0006] In the drive device disclosed in US 2020 / 0381977 A1 , screws are used for fastening the cover element to the housing, which has several drawbacks: Generally, a large number of screws is required for fastening the cover element. This increases the costs of the drive device and causes a long cycle time for individually applying the screws to the cover. Further, during screwing, metallic particles can be cut from the housing and may undesirably get in contact with the electric component. Also, a screw connection is relatively sensitive to thermal changes, which may cause a detachment of the cover from the housing under extreme thermal conditions.

[0007] It is an object of the present invention to provide an improved, in particular more manufacturing-friendly and / or more robust, possibility for fastening a cover element to a housing of an electric drive.

[0008] This object is solved by an electric drive as initially described, wherein the cover element is fastened to the wall for closing the accommodation space with regard to the exterior of the electric drive by means of at least one crimp joint.

[0009] By using the at least one crimp joint for fastening the cover element to the wall, expensive screws can be omitted. A corresponding crimping process can be performed with a shorter cycle time in comparison to individually applying screws. Also, crimping can be performed without the abrasion of metallic particles, which may cause malfunctions of the electric component. As a further advantage, the at least one crimping joint is more difficult to be removed, which prevents an unauthorized opening of the accommodation space and unauthorized access to the electric component.

[0010] As a further another advantage, the at least one crimp joint fulfills a sealing function against the housing inside. The at least one crimp joint can prevent from ingress of humidity from ambient / outside and / or prevent form leading to short circuit. As a further advantage, by crimping, the circumferential seal under the cover is pressed homogeneously.

[0011] The electric machine could be any type of electrical motor. For instance, the electric machine may be a synchronous motor, which may be electrically or permanently excited. Alternatively, the electric machine is an asynchronous motor or an induction motor. The electric component may be a high-voltage electrical component, i.e. an electric component configured to be operated with a voltage of more than 60 volts during operation of the electric drive. The housing is preferably made of metal, such as aluminum. The housing may be a cast housing. As seen upon the accommodation space, the wall may form a closed line, which may be in particular polygon-shaped. The cover element may be made of metal, such as aluminum. The contact face may be a flat surface. In an embodiment, the housing can be made of plastic.

[0012] Especially, the cover element is fastened to the wall without an additional fastening element that applies a perpendicular force to the cover element and the contact face. That is, no screws, bolts, rivets or the like may be provided for fastening the cover element to the housing.

[0013] According to a preferred design of the electric drive, the wall surrounds the accommodation space and extends away from the accommodation space for forming the contact face and an opposing face at a free end of the wall.

[0014] According to a first design alternative, the electric drive may further comprise a number of crimping elements corresponding to the number of crimp joints. Therein, each crimping element may be crimped around the outer side of the cover element, the free end and the opposing face of the wall. Each crimping element may be formed by a metal sheet being deformed for being crimped.

[0015] Preferably, grooves are formed with the outer side of the cover element and / or the opposing face. The crimping element may be crimped into the grooves.

[0016] According to a second design alternative, the cover element may be crimped around the free end of the wall to the opposing face for forming at least one crimp joint. That is, the cover element itself is deformed for realizing the crimp joint.

[0017] With regard to the electric drive according to the invention, the cover element may have multiple straight sections and corner sections connecting the straight section. Preferably, for each straight section one crimp joint is provided, wherein a respective crimp joint that fastens the cover element at one of the straight sections is formed separately from crimp joints that fasten the cover element to other ones of the straight sections. Forming multiple crimp joints is particularly advantageous, when rather complicated shapes of the contact face are provided. Alternatively, a single crimp joint is provided extending along the straight sections and the corner sections. This allows to realize the crimp joint in a single crimping process.

[0018] In a preferred design of the electric drive according to the invention, the inner side of the cover element is provided with a first positioning element and the contact face is provided with a second positioning element being formed inversely with regard to the first positioning element and engaging the first positioning element. This allows positioning the cover element upon the contact face prior to performing the crimping process. The second position element may be a projection formed with the contact face or a deepening formed with the contact face. Of course, multiple first and second positioning elements may be provided along the extent of the contact face.

[0019] Preferably, the accommodation space is further limited by a bottom facing the cover element and being formed by the housing.

[0020] Therein, the housing may form a further accommodation space, inside which the electric machine is disposed. The further accommodation space may be formed on a side of the housing opposite to the bottom. That is, the housing may integrally form the accommodation spaces as a single housing part. Note that the accommodation space for the electric component may be referred to as first accommodation space and the further accommodation space may be referred to as second accommodation space.

[0021] Alternatively, the electric drive may comprise a further housing, inside which the electric machine is disposed, the housings being fastened to each other. Note that the housing for the electric component may be referred to as first housing and the further housing may be referred to as second housing.

[0022] The housing may form a further (or third) accommodation space corresponding to the first accommodation space and the electric drive according to the invention may comprise a second cover element and a second electrical component being disposed in inside the third accommodation space. All statements concerning the first accommodation space and the first cover element may apply analogously to the third accommodation space and the second cover element.

[0023] Preferably, the electric drive is provided with an inverter configured to supply an AC voltage to the electric machine. Preferably, the inverter forms the electric component. Alternatively, the electric component may be connection device for connecting the inverter with the electric machine. Also, one of the first or second electrical components may be the afore-said inverter and the other one of the electrical components may be the afore-said connection device.

[0024] The above object is further solved by a method for manufacturing an electric drive for a vehicle, the method comprising steps of: providing a housing which forms an accommodation space limited by a wall of the housing; disposing an electrical component inside the accommodation space; disposing a cover element with an outer side and an inner side opposing the outer side upon the wall such that the inner side of the cover element is situated upon a contact face formed by the wall and that the inner side of the cover element limits the accommodation space; fastening the cover element to the wall for closing the accommodation space with regard to the exterior of the electric drive by forming at least one crimp joint; and providing a rotating electric machine to the electric drive.

[0025] Preferably, the accommodation space is further limited by a bottom facing the cover element and being formed by the housing, the housing forming a further accommodation space being formed on a side of the housing opposite to the bottom. Then, the method may comprise a step of disposing the electric machine inside the further accommodation space.

[0026] Alternatively, the method may comprise further steps of: providing a further housing; disposing the electric machine inside the further housing; and fastening the housings to each other.

[0027] The step of fastening the cover element to the wall may comprise: providing a number of crimping elements corresponding to the number of crimp joints and crimping each crimping element around the outer side of the cover element, the free end and the opposing face of the wall. Therein, grooves may be formed with the outer side of the cover element and / or the opposing face, wherein the crimping element is crimped into the grooves.

[0028] The step of fastening the cover element to the wall may comprise: crimping the cover element around the free end of the wall to the opposing face for forming the at least one crimp joint.

[0029] Before the step of fastening the cover element, the method may comprise: positioning the cover element upon the contact face, wherein the inner side of the cover element is provided with a first positioning element and the contact face is provided with a second positioning element being formed inversely with regard to the first positioning element; and engaging the first and second positioning elements.

[0030] All statements regarding the above electric drive apply analogously to the method according to the invention so that the advantages described above may be achieved by the method as well.

[0031] Further details and advantages of the invention are disclosed in the following, wherein reference is made to the enclosed drawings. The drawings show schematically: Fig. 1 a diagram of a first embodiment of the electric drive according to the invention;

[0032] Fig. 2 a cross-sectional view of the crimp joint according to the first embodiment;

[0033] Fig. 3 a top view of the cover element according to the first embodiment;

[0034] Fig. 4 a top view of the cover element according to a second embodiment of the electric drive according to the invention;

[0035] Fig. 5 a cross-sectional view of the crimp joint according to a third embodiment of the electric drive according to the invention;

[0036] Fig. 6 a cross-sectional view of the crimp joint according to a fourth embodiment of the electric drive according to the invention;

[0037] Fig. 7 a diagram of a fifth embodiment of the electric drive according to the invention; and

[0038] Fig. 8 a principle drawing of a vehicle with an electric drive according to the invention.

[0039] Fig. 1 is a diagram of a first embodiment of the electric drive 1 according to the invention.

[0040] The electric drive 1 comprises a rotating electric machine 2, such as a permanently or electrically excited synchronous motor or an induction motor. Further, the electric drive 1 comprises a first cover element 3 with an outer side 4 and an inner side 5 opposing the outer side 4 and a housing 6. The housing 6 forms a first accommodation space 7, which is limited by a wall 8 (see Fig. 3) of the housing 6 and the inner side 5 of the first cover element 3. Inside the first accommodation space 7, an electrical component 9 is disposed. The housing 6 can be realized as a casted aluminum housing.

[0041] Further, the housing 6 forms a second accommodation space 10, inside which the electric machine 2 is disposed. The second accommodation space 10 is formed on a side of the housing opposite to a bottom 1 1 of the first accommodation space 7.

[0042] Optionally, the housing 6 forms a third accommodation space 12 and the electric drive comprises a second cover element 13. The third accommodation space 12 and the second cover element 13 correspond substantially to the first accommodation space 9 or first cover element 4, respectively. Nonetheless, the third accommodation space 12 and the second cover element 13 may differ in their sizes from the first accommodation space 9 or the first cover element 4, respectively. Inside the third accommodation space 12, a second electrical component 14 is disposed.

[0043] In the present embodiment, the first electrical component 9 is an inverter configured to supply an AC voltage to the electric machine 2. The optional second electrical component 14 is a connection device for connecting the inverter with the electric machine 2. Alternatively, the first electrical component 9 may the connection device and the inverter may be disposed otherwise.

[0044] As further optional component of the electric drive 1 , a gearbox 14a, which is mechanically connected to the electric machine 2, is indicated schematically in Fig. 1 .

[0045] Fig. 2 is a cross-sectional view of a crimp joint 20 according to the first embodiment.

[0046] As already mentioned, the first cover element 3 limits the first accommodation space 7. Further, the first accommodation space 7 is limited by a wall 15 of the housing 6. The inner side 5 of the first cover element 3 is situated upon a contact face 16 formed by the wall 15. The wall 15 extends away from the first accommodation space 7 for forming the contact face 16 and an opposing face 17 at a free end 18 of the wall 15.

[0047] The first cover element 3 is fastened to the wall 15 for closing the accommodation space 7 with regard to an exterior E of the electric drive 1 by means of a crimp joint 20. In the present embodiment, the crimp joint 20 is realized by a crimping element 21 being crimped around the outer side 4 of the first cover element 3, the free end 18 and the opposing face 17 of the wall 15.

[0048] Further, Fig. 2 shows optional positioning elements 19a, 19b, which facilitate to situate the cover element 3 upon the contact face 16 during manufacturing. Therein, the inner side 5 of the first cover element 3 is provided with a first positioning element 19a and the contact face 16 is provided with a second positioning element 19b, which is formed inversely with regard to the first positioning element 19a and engaging therewith. Multiple pairs of positioning elements 19a, 19b are distributed along the contact face 16 and an edge of the cover element 3. In the present embodiment, the second position element 19b is a projection formed with the contact face 16 and the first positioning element 19a is a deepening formed with the contact face 3. According to alternative embodiments, the first position element 19a is a projection and the second positioning element 19b is a deepening.

[0049] Fig. 3 is a top view on the first cover element 4 according to the first embodiment.

[0050] The first cover element 3 has multiple straight sections 22 and corner sections 23 connecting the straight section 22. In the present embodiment, a single crimp joint 20 is provided extending along the straight sections 22 and the corner sections 23.

[0051] In the following, further embodiments are described. Therein, all statements regarding the first embodiment apply to the further embodiment unless differences are mentioned. Equal or equivalent components are denoted with identical reference numerals. Fig. 4 is a top view of the first cover element 3 according to a second embodiment of the electric drive according to the invention.

[0052] In this embodiment, for each straight section 22 one crimp joint 20 is provided. Exemplarily, six straight sections 22 are depicted in Fig. 4. A respective crimp joint 20 that fastens the first cover element 3 at one of the straight sections 22 is formed separately from crimp joints 20 that fasten the first cover element 3 to other ones of the straight sections 22.

[0053] Fig. 5 is a cross-sectional view of the crimp joint 20 according to a third embodiment of the electric drive 1 .

[0054] In this embodiment, grooves 24, 25 are formed with the outer side 4 of the first cover element 3 and the opposing face 17 of the wall 15. For a higher joining quality, the crimping element 21 , i.e. its free ends, is crimped into the grooves 24, 25. Note that, as alternatives, grooves 24 may be formed with the first cover element 3 only or that grooves 25 may be formed with the wall 15 only.

[0055] Grooves 24, 25 may also be provided with the second embodiment so that a respective one of the crimping element 21 is crimped into the grooves 24, 25.

[0056] Fig. 6 is a diagram of a fourth embodiment of the electric drive according to the invention.

[0057] In this embodiment, the first cover element 3 is crimped around the free end 18 of the wall 15 to the opposing face 17 for forming the single crimp joint 20. In accordance with the second embodiment (see Fig. 4), the straight sections 22 of the first cover element 3 may be respectively crimped around the free end 18, whereas the corner sections 23 are not crimped. In all afore-said embodiments, the second cover element 13 may be fastened to a corresponding contact face of a further wall of the housing 6, upon which the inner side of the second cover element 13 is situated, by means of at least a further crimp joint corresponding any of the afore-said embodiments.

[0058] Although not shown in Fig. 5 and Fig. 6 positioning elements 19a, 19b as described with regard to the first embodiment may be provided in the first to fourth embodiment as well.

[0059] Fig. 7 is a diagram of a fifth embodiment of an electric drive 1 .

[0060] In this embodiment, a second housing 26 is provided, which forms the second accommodation space 10, inside which the electric machine 2 is disposed. The first housing 6 and the second housing 26 are fastened to each other. The third accommodation space 12 is not shown for reasons of simplicity or can be omitted.

[0061] Fig. 8 is a principle drawing of a vehicle 100 with an electric drive 1 according to any of the afore-said embodiments.

[0062] The electric drive 1 is configured to propel the vehicle 100. The electric vehicle 100 comprises wheels 101 coupled with the electric drive 1 so as to rotate the wheels 101 . According to the embodiment, the electric vehicle 100 is a battery electric vehicle (BEV). Alternatively, the electric vehicle 100 may additionally comprise a combustion engine, therein forming a hybrid vehicle. Further, the electric vehicle 100 may comprise a fuel cell supplying the stator windings 5 of stator 3.

Claims

Claims1 . Electric drive (1 ) for a vehicle (100), the electric drive (1 ) comprising: a rotating electric machine (2); a cover element (3) with an outer side (4) and an inner side (5) opposing the outer side (4); a housing (6) forming an accommodation space (7), which is limited by a wall (15) of the housing (6) and the inner side (5) of the cover element (3), the inner side (5) of the cover element (3) being situated upon a contact face (16) formed by the wall (15); and an electrical component (9) being disposed inside the accommodation space; characterized in that the cover element is fastened to the wall (15) for closing the accommodation space (7) with regard to the exterior (E) of the electric drive (1 ) by means of at least one crimp joint (20).

2. Electric drive according to claim 1 , wherein the wall (15) surrounds the accommodation space (7) and extends away from the accommodation (7) space for forming the contact face (16) and an opposing face (17) at a free end (18) of the wall (15).

3. Electric drive according to claim 2, further comprising a number of crimping elements (21 ) corresponding to the number of crimp joints (20), each crimping element (21 ) being crimped around the outer side (4) of the cover element (3), the free end (18) and the opposing face (17) of the wall (15).

4. Electric dive according to claim 3, wherein grooves (24, 25) are formed with the outer side (4) of the cover element (3) and / or the opposing face (16), the crimping element (21 ) being crimped into the grooves (24, 25).

5. Electric drive according to claim 2, wherein the cover element (3) is crimped around the free end of the wall (15) to the opposing face (17) for forming the at least one crimp joint (20).

6. Electric drive according to any of the preceding claims, wherein the cover element (3) has multiple straight sections (22) and corner sections (23) connecting the straight section (22).

7. Electric drive according to claim 6, wherein for each straight section (22) one crimp joint (20) is provided, wherein a respective crimp joint (20) that fastens the cover element (3) at one of the straight sections (22) is formed separately from crimp joints (20) that fasten the cover element (3) to other ones of the straight sections (22).

8. Electric drive according to claim 6, wherein a single crimp joint (20) is provided extending along the straight sections (20) and the corner sections (23).

9. Electric drive according to any of the preceding claims, wherein the inner side (5) of the cover element (3) is provided with a first positioning element (19a) and the contact face (16) is provided with a second positioning element (19b) being formed inversely with regard to the first positioning element (19a) and engaging the first positioning element (19a).

10. Electric dive according to any of the preceding claims, wherein the accommodation space (7) is further limited by a bottom (11 ) facing the cover element (3) and being formed by the housing (6).11 . Electric drive according to claim 10, wherein the housing (6) forms a further accommodation space (10), inside which the electric machine (2) is disposed, the further accommodation space (10) being formed on a side of the housing (6) opposite to the bottom (11 ).

12. Electric drive according to any of claims 1 to 10, further comprising a further housing (26), inside which the electric machine (2) is disposed, the housings (6, 26) being fastened to each other.

13. Electric drive according to any of the preceding claims, wherein the electric drive (1 ) is provided with an inverter configured to supply an AC voltage to the electric machine (2), wherein the inverter forms the electric component (9) or wherein the electric component (9) is a connection device for connecting the inverter with the electric machine (2).

14. Method for manufacturing an electric drive (1 ) for a vehicle (100), the method comprising steps of: providing a housing (6) which forms an accommodation space (7) limited by a wall (15) of the housing (6); disposing an electrical component (9) inside the accommodation space (7); disposing a cover element (3) with an outer side (4) and an inner side (5) opposing the outer side (4) upon the wall (15) such that the inner side (5) of the cover element (3) is situated upon a contact face (16) formed by the wall (15) and that the inner side (5) of the cover element (3) limits the accommodation space (7); fastening the cover element (3) to the wall (15) for closing the accommodation space (7) with regard to the exterior (E) of the electric drive (1 ) by forming at least one crimp joint (20); and providing a rotating electric machine (2) to the electric drive (1 ).

15. Method according to claim 14, wherein the accommodation space (7) is further limited by a bottom (1 1 ) facing the cover element (3) and being formed by the housing (6), the housing (6) forming a further accommodation space (10) being formed on a side of the housing (6) opposite to the bottom (6), wherein the method comprises astep of disposing the electric machine (2) inside the further accommodation space (10); or the method comprises further steps of: providing a further housing (26); disposing the electric machine (2) inside the further housing (26); and fastening the housings (6, 26) to each other.

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