Method for reconditioning or repairing an electric drive unit

Abstract

The invention relates to a method for reconditioning or repairing an electric drive unit (10) which comprises a system housing (13) and a stator housing (19) having a cylindrical shape and in which: an electric machine (11) having a stator (25) and a rotor (26) is arranged in the stator housing (19); the stator housing (19) is inserted into a hollow-cylinder-shaped chamber of the system housing (13) and is connected to the system housing (13) by means of an annular weld seam extending peripherally at an end of the stator housing (19) and of the system housing (13); and at least one cooling channel (38) is formed between the lateral surface of the stator housing (19) and the system housing (13). The method comprises: - separating the stator housing (19) from the system housing (13) by forming a groove along the annular weld seam, so that the stator housing (19), together with the electric machine (11), can be removed from the system housing (13) and the electric machine is accessible; then - introducing the ring, at the location of the groove with radial oversize; then - producing an integral joint between the stator housing (19), the ring and the system housing (13), so that the reconditioned or repaired electric drive unit (10) results.

Description

[0001] R. 415757

[0002] - 1 -

[0003] Description

[0004] title

[0005] Methods for reconditioning or repairing an electric drive unit

[0006] State of the art

[0007] For example, an electric drive unit is already known from the applicant's patent application WO 22 023 092 A1, comprising a system housing and a stator housing with a cylindrical shape, wherein an electric machine with a stator and a rotor is arranged in the stator housing, wherein the stator housing is inserted into a chamber with a hollow cylindrical shape of the system housing and is connected to the system housing via an annular weld seam circumferential on an end face of the stator housing and the system housing, and wherein at least one cooling channel is formed between the outer surface of the stator housing and the system housing.

[0008] Disclosure of the invention

[0009] The inventors recognized that it was not sustainable that, according to previous understanding, the weld between the stator housing and the system housing was considered an inseparable connection, or that these components were considered destroyed and disposed of after being separated from each other.

[0010] Such separation of the stator housing and the system housing may be necessary, for example, for the purpose of repairing or reconditioning the electric machine and / or the electric drive unit. R. 415757

[0011] - 2 -

[0012] In particular, when the stator housing and the system housing are separated “destructively” using a subtractive process, material is lost from the stator housing and / or the system housing, making it more difficult to later join the stator housing and the system housing together.

[0013] The present invention overcomes this difficulty through the following process steps:

[0014] - Separating the stator housing from the system housing by forming a groove along the annular weld seam, so that the stator housing with the electric machine can be removed from the system housing and the electric machine can be accessed; then

[0015] - Insert the ring into the groove with radial interference; then

[0016] - Establishing a material-bonded connection between the stator housing, the ring and the system housing, resulting in the refurbished or repaired electric drive unit.

[0017] The invention thus achieves the overall result that the system housing and the stator housing can be reused after the repair or refurbishment of the electric drive unit. The solution according to the invention is therefore more sustainable than the previously known solution.

[0018] It may be provided that at least one of the following process steps takes place after the stator housing has been separated from the system housing and before a material-bonded connection has been established between the stator housing, the ring and the system housing:

[0019] - Repair of the electric machine, for example the stator and / or the rotor;

[0020] - Replacement of the electric machine or part of the electric machine, for example the stator and / or the rotor;

[0021] - Performing a measurement on the electrical machine or on a part of the electrical machine, for example on the stator and / or on the rotor.

[0022] This process step(s) may be preceded in time by the removal of the stator housing from the chamber of the system housing R. 415757

[0023] - 3 - and the insertion of the stator housing into the chamber of the system housing will be subsequent in time.

[0024] The insertion of the ring at the location of the groove with radial interference can be carried out using techniques known per se, for example on the basis of thermal expansion.

[0025] The material-bonded connection(s) can be produced efficiently and reliably, for example, by means of friction stir welding.

[0026] First, a material-bonded connection can be established between the system housing and the ring, followed by a second material-bonded connection between the ring and the stator housing. Alternatively, the process can be reversed: first, the material-bonded connection between the ring and the stator housing is established, followed by the material-bonded connection between the system housing and the ring.

[0027] Alternatively, a material-bonded connection between the system housing, the ring, and the stator housing can be created using a single new circumferential annular weld. The radial extent of this weld is then greater than the radial extent (thickness) of the ring.

[0028] The stator housing, the system housing and / or the ring can be made of aluminum or an aluminum alloy.

[0029] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows:

[0030] Figures 1 and 2 show an example of an electric drive.

[0031] Figure 3 shows an exemplary and step-by-step process of the method according to the invention. R. 415757

[0032] - 4 -

[0033] Figures 1 and 2 show an example of an electric drive unit 10. Figure 1 shows a perspective view of the electric drive unit 10 integrated into a one-piece system housing 13. The system housing 13 has three cavities: a first cavity 14, a second cavity 15, and a third cavity 16. The first cavity 14 has a hollow cylindrical shape. The electric motor 11 is inserted into it. The second cavity 15 houses power electronics 12, and the third cavity 15 contains a gearbox 17. The power electronics 12 and the electric motor 11 are thus mounted in the one-piece system housing 13.

[0034] The electric drive unit 10 further comprises a power electronics cover 20, a gearbox cover 21, and a stator housing 19. The stator housing 19, with its outer contour and the corresponding counter contour in the system housing 13, forms a stator cooling jacket 38 through which coolant can be pumped. The electric machine 11 is cooled accordingly.

[0035] Figure 2 shows a sectional view of the electric drive unit 10 according to the invention with a one-piece rotor shaft 27 and gearbox input shaft 31.

[0036] A gearbox 17 is arranged in the third main chamber. The power electronics 12 are arranged on the outer casing of the electric machine 11. The gearbox 17 is arranged axially on the electric machine. The first main chamber 14 is sealed against the third main chamber 16, preferably with a radial shaft seal. The one-piece system housing 13 is preferably made of aluminum. The first main chamber 14 is closed by a stator housing, and the second main chamber 15 is closed by a power electronics cover. The gearbox 17 is a two-stage spur gear unit and includes a differential 22 and can be configured with or without a parking lock 23 and with or without a disconnect 24 (freewheel). The electric machine 11 comprises a rotor 25 and a stator 26, wherein the rotor 25 is arranged non-rotatably on a rotor shaft 27. The cooling jacket 38 with a R. 415757

[0037] - 5 -

[0038] Coolant is pumped through and discharged via a cooling water connection 33. The electric drive unit 10 has a one-piece rotor-gearbox input shaft 29, wherein a pinion 30 is arranged on the rotor-gearbox input shaft 29, which represents the pinion of a first gear stage 36 of the gearbox 17.

[0039] One embodiment of the method according to the invention is visualized as a flowchart in Figure 3. It comprises, for example, the following process steps. The arrows in Figure 3 symbolize an exemplary chronological sequence of the process steps:

[0040] - Providing an electric drive unit 10 as described above (step S1);

[0041] - Separating the stator housing 19 from the system housing 13 by forming a groove along the annular weld seam (step S2);

[0042] - Removal of the stator housing 19 from the system housing 13 (step S3);

[0043] - Repair, refurbishment or replacement of the electric machine 11 and subsequent insertion of the stator housing 19 into the hollow cylindrical chamber of the system housing 19 (step S4);

[0044] - Welding the ring onto the stator housing 19 and subsequently pressing the assembly of ring and stator housing 19 into the system housing 13 (step S5);

[0045] - Welding the assembly of ring and stator housing 19 to the system housing 13 by means of friction stir welding (step S6).

Claims

R. 415757 - 6 - Claims 1. A method for reconditioning or repairing an electric drive unit (10), wherein the electric drive unit (10) comprises a system housing (13) and a stator housing (19) of cylindrical shape, wherein an electric machine (11) with a stator (25) and a rotor (26) is arranged in the stator housing (19), wherein the stator housing (19) is inserted into a chamber having a hollow cylindrical shape in the system housing (13) and is connected to the system housing (13) by an annular weld circumferentially on an end face of the stator housing (19) and the system housing (13), and wherein at least one cooling channel (38) is formed between the outer surface of the stator housing (19) and the system housing (13), wherein the method provides the following steps: - Separating the stator housing (19) from the system housing (13) by forming a groove along the annular weld seam, so that the stator housing (19) with the electric machine (11) can be removed from the system housing (13) and the electric machine is accessible; then - Inserting a ring at the location of the groove with radial interference; then - Establishing a material-bonded connection between the stator housing (19), the ring and the system housing (13) resulting in the refurbished or repaired electric drive unit (10).

2. The method according to claim 1, wherein the production of a material-jointed connection is carried out at least partially by friction stir welding.

3. Method according to claim 1 or 2, wherein a material-bonded connection is first established between the system housing (13) and the ring. R. 415757 - 7 - and subsequently a material-bonded connection is made between the ring and the stator housing (19).

4. Method according to claim 1 or 2, wherein a material-bonded connection between the system housing (13), the ring and the stator housing (19) is produced by means of a single new circumferential annular weld.

5. Method according to one of the preceding claims, characterized in that the stator housing (19), the system housing (13) and / or the ring are made of aluminium or an aluminium alloy.

6. Method according to one of the preceding claims, characterized in that at least one of the following method steps is carried out after the separation of the stator housing (19) from the system housing (13) and before the creation of a material-bonded connection between the stator housing (19), the ring and the system housing (13): - Repair of the electric machine (11), for example of the stator (25) and / or the rotor (26); - Replacement of the electric machine (11) or part of the electric machine (11), for example the stator (25) and / or the rotor (26); - Performing a measurement on the electrical machine (11) or on a part of the electrical machine (11), for example on the stator (25) and / or on the rotor (26).

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