Electric machine unit with insert

Abstract

The invention relates to an electric motor unit (1) comprising an electric motor (2) having a rotor (3) and a stator (4), and a housing (5) with a housing wall that surrounds the electric motor (2). An insert (6) is positioned between the housing wall and the electric motor (2) and is positively connected to the housing wall. The present invention further relates to an electric axle drive system unit comprising such an electric motor unit (1). The present invention also relates to a method for manufacturing such an electric motor unit (1).

Description

[0001] The present disclosure relates to an electric machine unit comprising an electric machine or electric motor having a rotor and stator, and a housing comprising a housing wall surrounding the electric machine.

[0002] Products in the automotive sector, especially electric motors, are subject to numerous requirements and restrictions, which are clearly defined by legislation. Deviations from or exceeding these limits can have far-reaching consequences and may even lead to the electric motor losing its type approval.

[0003] With the advancing field of e-mobility and the associated high-voltage applications, new (strict) regulations are emerging, particularly in this area, for example, regarding the electromagnetic compatibility (EMC) of electric motors. EMC is a result of complex interactions within the electric motor or a complete electric axle drive unit, and readjusting these within the electric motor or the electric axle drive unit, and potentially installing additional components, especially in later development phases, requires considerable effort and generates high costs.

[0004] Therefore, new connection technologies are necessary to achieve high flexibility in the design of the electric axle drive units on the one hand, and low installation space consumption and minimal impairment of the design on the other.

[0005] If an electric axle drive system exceeds the permissible EMC values, the emissions of electromagnetic waves can theoretically be reduced by increasing the capacitance around the electric motor. This would require bringing the housing wall surrounding the electric motor as close as possible and covering as large an area as possible to the electric motor, or more specifically, to the rotor of the electric motor.

[0006] Moving the housing wall, especially in a late development phase of the electric motor, represents a significant intervention in the design of the electric axle drive unit. Furthermore, due to required rigidity, the housing wall is often ribbed, meaning that the rib height prevents the housing wall from being fully, i.e., with a 360° contact area, against the electric motor or the electric motor rotor.

[0007] Against this background, the present disclosure aims to provide an electrical machine unit that solves the problems described above and, more specifically, enables flexible adaptation of the electrical machine unit to environmental conditions. In particular, the electrical machine unit should remain within the limits set with regard to EMC regulations.

[0008] This problem is solved by the subject matter with the features of the independent claim and by the subject matter with the features of the dependent claims. Advantageous embodiments are the subject of the dependent claims.

[0009] The electric motor unit according to independent claim 1 comprises an electric motor with a rotor and stator, and a housing having a housing wall that surrounds the electric motor. According to the invention, an insert is placed between the housing wall and the electric motor, which is positively connected to the housing wall.

[0010] This insert can then be used, for example, to meet EMC requirements. Alternatively, it can also be used to meet NVH (Noise, Vibration, Harshness) requirements. Another alternative is to cover any rib structures in the housing wall, thus optimizing airflow within the electric motor unit.

[0011] Preferably, the insert is electrically conductive. In particular, the insert is made of (electrically conductive) metal. This allows the capacitance of the electric motor to be (indirectly) increased, thereby reducing the electromagnetic waves emitted by the electric motor. This improves EMC (electromagnetic compatibility) and makes it possible to comply with legal EMC limits.

[0012] In particular, the insert is intended to be connected to the housing wall via a friction rivet connection. With such a friction rivet connection, rivets on the insert or the housing wall engage in holes in the other component and are deformed by heat and pressure. These deformed rivets cannot be removed from the holes, so the housing wall and insert are firmly and positively locked together and therefore cannot be (non-destructively) disassembled. In contrast, conventional connection methods disadvantageously require modifications to the housing, and, for example, with a screw connection, the screw-in depths must be maintained. To ensure the required screw-in depths on the housing, material build-up would be necessary. Generally, screw connections require a large amount of axial space for the screw-in depths and thread production, which is often not available.These disadvantages can be overcome with the friction rivet connection, which itself requires only minimal installation space.

[0013] Furthermore, it is conceivable that rivets / pins / studs, particularly cylindrical ones, are molded onto the housing wall to create the friction rivet connection. These rivets, or rather their shape, can be easily inserted into the mold intended for the housing or housing wall. The housing is not weakened by the application of the rivets, and this does not require any further modifications to the housing. Another advantage of using rivets on the housing is the possibility of implementation in the raw casting; that is, to ensure functionality, the rivets do not require any machining of the housing, thus eliminating the associated costs.

[0014] Preferably, these rivets are integrally formed, particularly of a single material, i.e., cast in one piece, with the housing or housing wall. In this way, the rivets form a section of the housing and cannot be removed from it. This ensures, among other things, a secure connection with the insert.

[0015] It is further preferred if through holes are provided on the insert for creating the friction rivet connection, which are designed to be complementary to the rivets. In this way, the insert can be easily placed on the housing wall by interlocking the rivets and through holes. The through holes are thereby slipped over or slid over the rivets.

[0016] Furthermore, it can be provided that when the insert rests against the housing wall and the rivets engage in the through-holes, the rivets are deformed by friction, creating a (non-removable) positive-locking connection between the housing wall and the insert. This friction rivet connection can advantageously be implemented in an extremely small installation space.

[0017] Furthermore, it can be provided that the housing wall is positively connected to the insert at an axial end section of the housing facing the rotor. At the point where the housing faces the rotor, it is simplest and most practical to provide an insert that serves, in particular, to meet the (legal) EMC requirements.

[0018] Furthermore, the insert may be designed to ensure electromagnetic compatibility (EMC insert), a housing structure optimized for reducing vibrations in the electric motor unit (NVH-optimized), or a cover for ribbed structures on the housing wall. Accordingly, different inserts can be selected to address the specific problem at hand.

[0019] Furthermore, the insert can be designed as a circular disc with a central through-opening. If the insert has this shape, it can be mounted particularly flat and close to the housing wall. Thus, the insert is adapted to the shape of the housing wall.

[0020] Furthermore, the problem underlying the present disclosure is solved by an electric axle drive system unit, in particular for an electric vehicle, according to the dependent claim. The electric axle drive system unit, which comprises the electric motor unit according to the invention and a transmission, has the advantages associated with the electric motor unit according to the invention (and previously described).

[0021] Furthermore, the problem underlying the present disclosure can be solved by a method for manufacturing the E-machine unit according to the invention. The method comprises the following steps, which are preferably carried out in this order: a) Forming rivets onto the housing wall and creating through holes in the insert, b) Placing the insert (directly) against the housing wall, with the rivets engaging in the through holes, c) Heating the rivets (by friction), and d) Applying pressure to the heated rivets so that they deform (irreversibly) (plastically).

[0022] This method can be used to manufacture the E-machine unit according to the invention, which has the advantages described above.

[0023] The revelation is explained below with the help of drawings. They show: Fig. 1 a cross-sectional view of the E-machine unit according to the invention; Fig. 2A a perspective view of the housing wall and insert; Fig. 2B a perspective view of the housing wall and the insert which is arranged on the housing wall; Fig. 2C a cross-sectional view along line II in Fig. 2B; Fig. 2D, the vertically rotated cross-sectional view from Fig. 2C with a tool before deformation of the rivet; and Fig. 2E the vertically rotated cross-sectional view from Fig. 2C with the tool when the rivet is deformed.

[0024] The figures are purely schematic and serve only to illustrate the invention. The same elements are identified by the same reference symbols.

[0025] Fig. Figure 1 is a cross-sectional view of the electric machine unit 1 according to the invention. The electric machine unit 1 comprises an electric machine 2 (only a section of the electric machine 2 is shown here). The electric machine 2 has a rotor 3 and a stator 4. The electric machine 2 is shown here only schematically. The electric machine unit also comprises a housing 5. The housing 5 has a housing wall that typically surrounds the electric machine 2. In other words, the housing 5 (completely) contains or houses the electric machine 2. Fig. Only a small section of the housing 5 is visible in 1.

[0026] An insert 6 is arranged directly on the housing 5. Fig. Figure 1 shows a connection state of the E-machine unit 1 in which housing 5 and insert 6 are positively connected to each other.

[0027] The insert 6 is positioned between the housing 5 and the electric motor 2. The housing 5 has a rivet 7. The rivet 7 is arranged on a housing projection 8. The rivet 7 is formed integrally with the housing projection 8. The rivet 7 is thus a section of the housing 5 or of its housing wall.

[0028] The insert 6 has a through-hole 9. On its underside, facing the housing 5, the insert 6 has an insert projection 10a that extends around the through-hole 9. At the point where the insert has the insert projection 10a on its underside, the insert 6 is recessed on its upper side (facing the electric motor 2). In other words, the insert 6 forms a recess 10b around each of the through-holes 9 on its upper side.

[0029] The insert 6 rests with its projection 10 on the housing projection 8. The rivet 7 protrudes through the through-hole 9. In the area of ​​the through-hole 9, the rivet 7 is at most as wide as the through-hole 9. It can be seen that the tip of the rivet 7 is flattened, so that the rivet 7 is wider at this point than the through-hole 9. The tip of the rivet 7 is thus shaped like a head. In this way, the rivet 7 cannot move out of the through-hole 8, and the insert 6 can no longer be removed from the rivet 7 (without damage). Accordingly, the insert 6 and the housing 5 are in Fig. 1. The rivets are connected to each other by a friction rivet connection (irreversible or not detachable without damage). The flattened section of the tip of the rivet 7 (head) rests on the recess 10b of the insert 6. In the connected state, the rivet 7 does not protrude beyond the top surface of the insert 6, but remains within the recess 10b.

[0030] The insert 6 is particularly connected to the section of the housing wall that faces the rotor 3. It is conceivable that the two sections of the housing wall, each facing the two longitudinal ends of the rotor 3 (in Fig. 1 (only one longitudinal end of the rotor 3 is shown) are each connected to an insert 6. In other words, the E-machine unit 1 according to the invention then comprises two inserts 6 (not shown here).

[0031] The Fig. Figures 2A to 2B show a sequence of steps in which the insert is placed on the housing. Figures 2C to 2E then illustrate how the connection between the insert and the housing is achieved.

[0032] Fig. Figure 2A shows a perspective view of the housing wall of housing 5 and the insert 6. The insert 6 is still spaced apart from housing 5. Only an axial end section of housing 5 is shown here, which in practice faces the rotor 3. It can be seen that the housing wall has a ribbed structure on its inner side, i.e., on the side facing the rotor 3. In the center, the housing wall has a housing opening 11, which is circular. Ribs 12 extend outwards from this housing opening 11 (spoke-like).

[0033] A plurality of housing projections 8 are arranged at intervals along a line concentric with the housing through-opening 11. A rivet 7 is arranged or placed on each housing projection 8.

[0034] The insert 6 is designed as a circular disc. Like the housing 5, the insert 6 also has a central through-opening 13. The through-opening 13 has a larger diameter than the housing through-opening 11. A plurality of spaced-apart through-holes 9 are provided along a line arranged concentrically with the through-opening 13. The distance between the through-holes 9 corresponds to the distance between the rivets 7 and the housing projections 8.

[0035] Although it is not visible here, the (annular) insert projection 10 is provided on the (underside) of the insert 6 facing the housing 5, at the same level as the through holes 9.

[0036] Fig. Figure 2B shows a perspective view of the housing wall of housing 5 and the insert 6, which is positioned against and rests on the housing wall (but before the connection is established). More precisely, the insert projection 10 rests on the individual housing projections 9 (not visible). The rivets 7 protrude outwards through the through-holes 9. However, the rivets 7 do not extend beyond the top surface of the insert 9.

[0037] Fig. 2C is a cross-sectional view along line II in Fig. 2B. This view is identical to the view according to Fig. 1, apart from the fact that rivet 7 is not yet deformed here. Thus, this cross-sectional view shows that rivet 7 (before deformation) has a constant width or diameter along its entire length, which corresponds at most to the width or diameter of the through-hole 9. The tip of rivet 7 is therefore no wider than the rest of the rivet. The tip of rivet 7 lies approximately in the same plane as the top surface of insert 6. Rivet 7 definitely does not protrude beyond the top surface of insert 6. In Fig. 2C shows that the (circular) insert projection 10a rests on the individual housing projections 9.

[0038] Fig. 2D shows the cross-sectional view rotated vertically. Fig. 2C with a tool 14 before deformation of the rivet 7. The tool 14 is in contact with the tip of the rivet 7. The tool 14 is rotated about its longitudinal axis in the direction of rotation R. This rotation generates friction due to the contact between the tool 14 and the rivet 7. The resulting frictional energy heats the tip of the rivet 7. Due to the heat, the rivet 7 softens in the area of ​​its tip.

[0039] Fig. Figure 2E shows the cross-sectional view rotated vertically. Fig. 2C with the tool 14 during deformation of the rivet 7. The tool 14 is pressed downwards in the pressure direction D towards the (soft) rivet 7, so that it deforms and the connection state results which is described in Fig.As already shown in Figure 1, the deformation causes the tip of the rivet 7 to form a head that protrudes beyond the through-hole 9 of the insert 6. Therefore, the insert 6 can no longer be removed (non-destructively) from the housing 5. Reference symbol list 1 electric machine unit 2 electric machines 3 Rotor 4 Stator 5 cases 6 deployment 7 rivets 8 Housing protrusion 9 through hole 10a Operational advantage 10b Advanced 11 Housing through-opening 12 ribs 13 Insertion passage opening 14 tools D Pressure direction R direction of rotation

Claims

E-machine unit (1) with an E-machine (2) having a rotor (3) and stator (4), and with a housing (5) having a housing wall surrounding the E-machine (2), characterized in that an insert (6) is placed between the housing wall and the E-machine (2), which is positively connected to the housing wall. E-machine unit (1) according to claim 1, wherein the insert (6) is connected to the housing wall by friction rivet connection. E-machine unit (1) according to claim 2, wherein a plurality of rivets (7) are formed on the housing (5) to produce the friction rivet connection. E-machine unit (1) according to claim 3, wherein a plurality of through holes (9) are provided on the insert (6) for producing the friction rivet connection, which are designed to be complementary to the rivets (7). E-machine unit (1) according to claim 4, wherein, when the insert (6) rests against the housing wall and the rivets (7) engage in the through holes (9), the rivets (7) are frictionally deformed, so that the positive locking connection between the housing wall and the insert (6) is created. E-machine unit (1) according to one of claims 1 to 5, wherein the housing wall is positively connected to the insert (6) at the axial end section of the housing (5) which faces the rotor (3). E-machine unit (1) according to one of claims 1 to 6, wherein the insert is an insert to ensure electromagnetic compatibility and / or a housing structure to reduce vibrations in the E-machine unit and / or a cover to cover rib structures on the housing wall. E-machine unit according to one of claims 1 to 7, wherein the insert is designed as a circular disk with a central insert through-opening (13). Electric axle drive system unit comprising an electric machine unit (1) according to one of the preceding claims and a gearbox. Method for manufacturing an electric machine unit (1) according to one of the preceding claims, characterized by the following steps: e) forming rivets (7) onto the housing wall and forming through holes (9) on the insert, f) placing the insert (6) on the housing wall, wherein the rivets (7) engage in the through holes (9), g) heating the rivets (7), and h) applying pressure to the heated rivets (7) so that they deform.

Images