Electric drive for a vehicle, method for manufacturing an electric drive and vehicle

Abstract

Electric drive (1) for a vehicle (100), wherein the electric drive (1) comprises the following: - an electric machine (2) with a rotor (3) and a stator (4) comprising a stator core (5) with a first end face (6) and a second end face (7) and a stator winding forming phase connection terminals (10); - an inverter (11); - a connecting means (12) that electrically connects the inverter (11) to the phase connection terminals (10) in order to supply a multi-phase AC voltage from the inverter (11) to the phase connection terminals (10); and - a housing (13) comprising the following: i. a base element (14) in which the inverter (11) is housed, wherein the base element (14) has a collar (26), the collar (26) forming a first mounting surface (27) on which the first end face (6) of the stator core (5) is arranged, and a recess (28) at a circumferential position where the connecting means (12) is connected to the phase connection terminals (11), ii. an end shield element (20) which faces the second end face (7) of the stator core (5), and iii. a sheath element (21) that is arranged between the base element (14) and the end shield element (20) and covers the recess (28) and an outer circumference of the stator (4).

Description

[0001] The present invention relates to an electric drive for a vehicle. The invention also relates to a method for manufacturing an electric drive for a vehicle and a vehicle.

[0002] Electric drives that combine an electric machine and an inverter in a common housing can be used in automotive applications to propel a vehicle. For example, US 2020 / 0381977 A1 discloses a drive device for a vehicle. The drive device comprises an electric machine, a power converter, and a connecting device. The connecting device provides an electrical connection between the electric machine and the power converter. The drive device has a housing that accommodates the electric machine, the power converter, and the connecting device.

[0003] The drive device according to US 2020 / 0381977 A1 includes a specially provided housing section for a connecting element formed by the connecting device mentioned therein. This housing section has an opening that is releasably closed by a cover to allow access to the connecting elements. In the manufacture of such a drive device, the connection between the inverter and the electric machine is made through this opening. The opening is then closed by the cover. The cover must be provided with a gasket to prevent liquids from entering the housing and with a locking mechanism designed to disconnect live components behind the cover when the cover is removed. The cover is typically secured to the housing by a number of screws.

[0004] A disadvantage is that fastening the numerous screws requires considerable time, and each screw can fail, for example, due to thermal influences on the screw connection. Furthermore, the separate cover, seal, and locking mechanism increase the number of components in the electric drive and thus its manufacturing costs.

[0005] One object of the present invention is to provide an improved method for manufacturing an electric drive for a vehicle.

[0006] This problem is solved by an electric drive for a vehicle, the electric drive comprising: an electric machine with a rotor and a stator, the stator core having a first end face and a second end face and a stator winding forming phase connection terminals; an inverter; a connecting means that electrically connects the inverter to the phase connection terminals in order to supply a multiphase AC voltage from the inverter to the phase connection terminals;and a housing comprising: a base element in which the inverter is housed, the base element having a collar, the collar forming a first mounting surface on which the first end face of the stator core is arranged, and a recess at a circumferential position where the connecting means is connected to the phase connection terminals, an end shield element facing the second end face of the stator core, and a shell element arranged between the base element and the end shield element, covering the recess and an outer circumference of the stator.

[0007] The electric drive according to the invention comprises an electric machine. The electric machine has a rotor and a stator. The stator comprises a stator core. The stator core has a first end face and a second end face. The stator further comprises a stator winding that forms phase connection terminals. The drive device further comprises an inverter and a connecting means. The connecting means electrically connects the inverter to phase connection terminals in order to supply a multiphase AC voltage from the inverter to the phase connection terminals.

[0008] The electric drive according to the invention further comprises a housing. The housing includes a base element. The inverter is housed in the base element. The base element has a collar. The collar forms a first mounting surface. The first end face of the stator core is arranged on the first mounting surface. The collar forms a recess at a circumferential position where the connecting element is connected to the phase connection terminals. The housing further comprises an end shield element. The end shield element faces the second end face of the stator core. The housing further comprises a casing element. The casing element is arranged between the base element and the end shield element. The casing element covers the recess and an outer circumference of the stator.

[0009] In the electric drive according to the invention, the collar provides the recess for access to the phase connection terminal for manufacturing or maintenance and also serves as the first mounting surface, acting as a support structure for the stator core. The outer shell closes the recess and thus fulfills two functions: receiving the stator and preventing access to the connection through the recess. Advantageously, conventional covers and their fastening means for closing a specially provided opening can be omitted, which reduces the cycle time and eliminates the fastening means as potential sources of error. Furthermore, no locking devices or seals are required for the conventional cover.

[0010] The electric machine can be a permanent magnet or electrically excited synchronous motor or an induction motor. Preferably, the electric machine is configured to operate with an operating voltage of at least 400 volts, particularly preferably at least 800 volts.

[0011] The stator winding can have three or six phases. The inverter can be configured to convert a DC voltage into a multi-phase AC voltage to be supplied to the stator winding. The electric drive can include connectors for linking the inverter to a DC voltage source, such as a high-voltage battery or a fuel cell.

[0012] The terms "axial" and "circumference..." refer to a rotational axis of the rotor. The terms "end faces" refer to opposite axial faces of the stator core.

[0013] The connector can be any electrical conductor suitable for electrical and mechanical coupling to the phase connection terminals. The connector can be implemented separately or integrated with the electrical wiring from the inverter. The connection can be made by welding, soldering, screwing, crimping, or any other suitable joining technique.

[0014] The electric drive according to the invention can further comprise a main shaft which is torque-fixed to the rotor. The end shield element can form an end shield, preferably a non-drive end shield, for the main shaft. The base element can form an end shield, preferably a drive end shield, for the main shaft. Furthermore, the electric drive according to the invention can comprise a gearbox and an output shaft. The output shaft can be coupled to the main shaft via the gearbox in order to transmit a rotary motion of the main shaft to the output shaft.

[0015] Preferably, the collar on the first end face encloses a winding head formed by the stator winding. The phase connection terminals can extend axially beyond the winding head from the first end face.

[0016] According to a preferred embodiment, the recess extends further in the axial direction than the winding head in order to provide sufficient working space for making the connection of the phase connection terminals and the connecting means.

[0017] Advantageously, the base element forms an end shield section with a first side from which the collar protrudes towards the stator core, and a second side opposite the first side.

[0018] The inverter can be located on the second side of the end shield section. In this configuration, the end shield section forms part of the housing that supports the inverter.

[0019] Preferably, the base element has a cover element attached to the second side of the end plate section, which closes an inverter mounting compartment in which the inverter is located. The cover element can be attached to the end plate section by means of screws or other suitable fasteners.

[0020] In particular, the end shield section forms an opening through which electrical cables are routed from the inverter to the connecting elements.

[0021] With regard to the electric drive according to the invention, the base element can form a second mounting surface surrounding the collar, with the outer shell element being located on this second mounting surface. The second mounting surface provides a defined support structure for the outer shell element.

[0022] To secure the casing element, the electric drive according to the invention can comprise fastening rods, each extending from the end shield element to the base element. The fastening rods can clamp the casing section between the end shield element and the base element and / or extend within the casing element.

[0023] The above problem is further solved by a method for manufacturing an electric drive for a vehicle according to the invention, the method comprising the following steps: providing the base element; arranging the first end face of the stator core on the first mounting surface such that the phase connection terminals are located at the circumferential position; connecting the phase connection terminals and the inverter at the circumferential position by means of the connecting means, wherein a tool is guided through the recess; and, after the inverter and the phase connection terminals have been connected, arranging the casing element to form the housing on the base element such that the casing element covers the recess and an outer circumference of the stator.

[0024] Preferably, the step of providing the base element includes providing the inverter housed in the base element and providing the connecting means connected to the inverter.

[0025] Advantageously, the method according to the invention comprises further steps: arranging the end shield element on the shell element such that the end shield element faces the second end face of the stator core; and clamping the shell section between the end shield element and the base element by means of the fastening rods, which each extend from the end shield element to the base element.

[0026] The above problem is further solved by a vehicle comprising an electric drive according to the invention or an electric drive obtained by the method according to the invention. The electric drive is configured to propel the vehicle.

[0027] All statements concerning the electric drive according to the invention apply analogously to the above method and to the vehicle, so that the above-mentioned advantages of the electric drive can be achieved by the method and also by the vehicle.

[0028] Further details and advantages of the invention will be disclosed below with reference to the drawings. The drawings schematically illustrate: Fig. 1 a block diagram of an embodiment of an electric drive according to the invention; Fig. 2 an exploded view of the electric drive; Fig. 3 a detailed view of the electric drive without the casing element; Fig. 4 a detailed view of the electric drive; Fig. 5 a flowchart of an embodiment of the method according to the invention; and Fig. 6 a schematic diagram of an embodiment of a vehicle according to the invention.

[0029] Fig. Figure 1 is a block diagram of an embodiment of an electric drive 1.

[0030] The electric drive 1 comprises an electric machine 2 with a rotor 3 and a stator 4. The electric machine 2 can be a permanent magnet or electrically excited synchronous machine or an induction machine.

[0031] The stator 4 comprises a stator core 5 with a first end face 6 and a second end face 7. The stator 4 further comprises a stator winding, which is indicated by first winding heads 8 at the first end face 6 and second winding heads 9 at the second end face 7. The stator winding forms phase connection terminals 10 at the first end face.

[0032] Furthermore, the electric drive 1 comprises an inverter 11 and a connecting means 12. The connecting means 12 electrically connects the inverter 11 to the phase connection terminals 10 in order to supply a multi-phase AC voltage from the inverter 11 to the phase connection terminals 10.

[0033] Fig. Figure 1 also shows a housing 13 of the electric drive 1.

[0034] The housing 13 comprises a base element 14 in which the inverter 11 is housed. In particular, the base element 13 forms an end shield section 15 and includes a cover element 16, which is attached to the end shield section 15 and closes an inverter mounting compartment 17 in which the inverter 11 is arranged. Furthermore, the end shield section 15 forms an opening 18 through which electrical lines 19 are led from the inverter 11 to the connecting element 12.

[0035] The housing 13 further comprises an end shield element 20 facing the second end face 7 of the stator core 5 and a shell element 21 arranged between the base element 14 and the end shield element 20. The shell element 21 covers the outer circumference of the stator 4.

[0036] The following are shown as optional components of the drive device 1 Fig. 1. A main shaft 22, which is torque-fixed to the rotor 3, and a gearbox 23, which is mechanically coupled to the main shaft 22. The gearbox 23 is configured to transmit a rotary motion of the main shaft 22 to an output shaft 24. In the present embodiment, the main shaft 22 and / or the output shaft 24 are arranged in the base element 14 of the housing 13. The end shield element 20 forms a non-drive end shield (ND shield, ND) for the main shaft 22, and the end shield section 15 of the base element 14 forms a drive end shield (DE shield, DE) for the main shaft 22.

[0037] Fig. Figure 2 is an exploded view of the electric drive 1.

[0038] The base element 14, in particular a first side 25 of the end shield section 15, has a collar 26 which forms a first fastening surface 27. The first end face 6 (in Fig. The stator core 5 (2, concealed) is located on the first mounting surface 27. The collar 26 also forms a cutout 28 at a circumferential position where the connecting element 12 is connected to the phase connection terminals 10. In an assembled state, the jacket section 21 covers the recess 28.

[0039] As described in more detail below using a manufacturing process, the recess 28 enables the connection between the connecting element 12 and the phase connection terminal 10 of the stator winding to be established by manual or automatic handling through the recess 28. After the connection has been established, the jacket section 21 forms the peripheral stator housing and closes the recess 28, thus eliminating the need for conventionally required, separate cover elements.

[0040] Specifically, the collar 26 surrounds the winding head 8 on the first end face 6. The recess 28 extends further in the axial direction than the maximum distance between the winding head 8 and the first end face 6. The phase connection terminals 10 extend axially beyond the winding head 8, viewed from the first end face 6. This means that the recess 28 provides sufficient working space to connect the phase connection terminals 10 to the connecting element 12.

[0041] Fig. Figure 2 shows the base element 14 in its assembled state. That is, the cover element 16 is attached to a second side (in Fig. 2 (concealed) of the end shield section 15 opposite the first side 25. The cover element 16 is attached to the end shield section by means of several screws 29. The inverter 11 (see Fig. 1) is located on the second side. The opening 18 (see Fig. 1) makes it possible to route the electrical lines 19 from the second side to the first side 25.

[0042] The Fig. 3 and Fig. Figures 4 each show a detailed view of the electric drive 1, with the casing section 21 in Fig. Number 3 is omitted.

[0043] The base element 14, in particular the first side 25 of the end shield section 15, forms a second fastening surface 30 that surrounds the collar 26 (see Fig. 3) How best to Fig. As can be seen in Figure 4, the sheathing element 21 is located on the second mounting surface 30.

[0044] The electric drive 1 further comprises fastening rods 31, each extending from the end shield element 20 to the base element 14. The fastening rods 31 clamp the casing section 21 between the end shield element 20 and the base element 14. The fastening rods 31 extend within the casing element 21. In the present embodiment, the fastening rods 31 engage with the base element 14.

[0045] The following describes an embodiment of a method for manufacturing an electric drive 1, such as the one described in the Fig. The embodiment shown in Figures 1 to 4 is described. Identical or equivalent components are designated with the same reference numerals.

[0046] Fig. Figure 5 is a flowchart of an embodiment of the manufacturing process 50.

[0047] The procedure includes step S1 of providing the base element 14. The base element 14 can be provided with or without the inverter 11 housed within it. Accordingly, the cover element 16 can already be attached to the end shield section 15 or can be attached to it after the inverter 11 has been installed.

[0048] In step S2, the first end face 6 of the stator core 2 is positioned on the first mounting surface 27 such that the phase connection terminals 10 are located at the circumferential position.

[0049] The procedure comprises step S3 of connecting the inverter 11 and the phase connection terminals 10 by means of a fastener 12 at the circumferential position. For this purpose, a tool is guided through the recess 28. The type of tool depends on the selected joining technique, which may be screwing, welding, soldering or crimping.

[0050] After connecting the connecting element 12 to the phase connection terminals 11, the sheath element 21 is arranged on the base element 14 to form the housing 13, so that the sheath element 21 covers the recess 28 and the outer circumference of the stator 4 (step S4).

[0051] According to step S5, the end shield element 20 is arranged on the shell element such that the end shield element 20 faces the second end face 7 of the stator core 5. This step may include attaching the rotor 3 to the end shield element 20 via the main shaft 22.

[0052] The procedure includes a step S6 of clamping the sheath section 21 between the end shield element 20 and the base element 14 by means of the fastening rods 31, which each extend from the end shield element 20 to the base element 14.

[0053] Fig. Figure 5 is a schematic diagram of an embodiment of a vehicle 100.

[0054] The vehicle 100 comprises an electric drive 1 according to the above embodiment or obtained from the above method. The electric drive 1 is configured to propel the vehicle 100.

[0055] The electric vehicle 100 comprises wheels 101 which are coupled directly or indirectly, e.g., via a power transmission, to the electric drive 1 in order to rotate the wheels 101. According to the embodiment, the electric vehicle 100 is a battery-electric vehicle (BEV). Alternatively, the electric vehicle 100 can additionally include an internal combustion engine, thus creating a hybrid vehicle. Furthermore, the electric vehicle 100 can include a fuel cell that supplies the electric drive 1. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2020 / 0381977 A1 [0002, 0003]

Claims

[1] Electric drive (1) for a vehicle (100), wherein the electric drive (1) comprises: - an electric machine (2) with a rotor (3) and a stator (4) comprising a stator core (5) with a first end face (6) and a second end face (7) and a stator winding forming phase connection terminals (10); - an inverter (11); - a connecting means (12) that electrically connects the inverter (11) to the phase connection terminals (10) in order to supply a multi-phase AC voltage from the inverter (11) to the phase connection terminals (10); and - a housing (13) comprising the following: i. a base element (14) in which the inverter (11) is housed, wherein the base element (14) has a collar (26), the collar (26) forming a first mounting surface (27) on which the first end face (6) of the stator core (5) is arranged, and a recess (28) at a circumferential position where the connecting means (12) is connected to the phase connection terminals (11), ii. an end shield element (20) which faces the second end face (7) of the stator core (5), and iii. a sheath element (21) that is arranged between the base element (14) and the end shield element (20) and covers the recess (28) and an outer circumference of the stator (4). [2] Electric drive according to claim 1, wherein the collar (26) surrounds a winding head (8) formed on the first end face (6) by the stator winding. [3] Electric drive according to claim 2, wherein the phase connection terminals (11) extend axially beyond the winding head (8) from the first end face (6). [4] Electric drive according to one of the preceding claims, wherein the base element (14) forms an end shield section (15) with a first side (25) from which the collar (26) protrudes to the stator core (3) and a second side which is opposite the first side (25). [5] Electric drive according to claim 4, wherein the inverter (11) is arranged on the second side of the end shield section (15). [6] Electric drive according to claim 4 or 5, wherein the base element (14) comprises a cover element (16) which is attached to the second side of the end shield section (15) and closes an inverter receiving space (17) in which the inverter (11) is arranged. [7] Electric drive according to one of claims 4 to 6, wherein the end shield section (15) forms an opening (18) through which electrical lines (19) are led from the inverter (11) to the connecting means (12). [8] Electric drive according to one of the preceding claims, wherein the base element (14) forms a second mounting surface (30) surrounding the collar (26), wherein the sheath element (21) is located on the second mounting surface (30). [9] Electric drive according to any of the preceding claims, further comprising: Fastening rods (31) extending from the end shield element (20) to the base element (14), wherein the fastening rods (31) clamp the sheath section (21) between the end shield element (20) and the base element (14), the fastening rods (31) extending inside the sheath element (21). [10] Method (50) for manufacturing an electric drive (1) for a vehicle (100) according to one of the preceding claims, wherein the method comprises the following steps (S1-S4): - Providing the basic element (14); - Arranging the first end face (6) of the stator core (5) on the first mounting surface (27) such that the phase connection terminals (10) are located at the circumferential position; - Connecting the phase connection terminals (10) and the inverter (11) at the circumferential position by means of a connecting means (12), whereby a tool is guided through the recess (28); - After connecting the phase connection terminals (10) and the inverter (11), arrange the sheath element (21) to form the housing (13) on the base element (14) such that the sheath element (21) covers the recess (28) and an outer circumference of the stator (4). [11] Method according to claim 10, wherein the step (S1) of providing the base element (14) includes providing the inverter (11) which is housed in the base element (14) and providing the connecting means (12) which is connected to the inverter (11). [12] Method according to claim 10 or 11, further comprising steps (S5, S6): - Arranging the end shield element (20) on the shell element (21) such that the end shield element (20) faces the second end face (7) of the stator core (5); and - Clamping the sheath section (21) between the end shield element (20) and the base element (15) by means of the fastening rods (31) which each extend from the end shield element (20) to the base element (15). [13] Vehicle (100) comprising an electric drive (1) according to any one of claims 1 to 9 or an electric drive (1) obtained by a method (50) according to any one of claims 10 to 12, wherein the electric drive (1) is configured to propel the vehicle (100).

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