METHOD FOR MANUFACTURING A HOUSING OF AN E-AXIS MODULE

Description

Technical field

[0001] The invention relates to the production of a housing of an e-axle module of an electrically driven vehicle, wherein the e-axle module comprises an electric machine and power electronics which are cooled via a cooling circuit. State of the art

[0002] DE 10 2008 001 621 A1 relates to an electrical machine with integrated housing cooling. The electrical machine comprises a housing having at least one housing wall. At least one electrical assembly is accommodated in this housing. Furthermore, a cooling device is provided, which has at least one coolant spray device for spraying the electrical assembly with coolant. It is further provided that the cooling device for housing cooling has at least one housing coolant channel for the coolant, which runs in the housing wall.

[0003] DE 20 2011 076 525 A1 relates to an electric drive for a vehicle. An electric drive for a vehicle is disclosed, comprising at least one electric machine and a transmission coupled to the electric machine, which are arranged in a common housing. A common cooling and / or lubricating circuit is provided for the electric machine and the transmission. The cooling and / or lubricating circuit comprises at least one heat sink on the electric machine and at least one distribution body for distributing the cooling and / or lubricating medium in the housing.

[0004] Further electrical machines are known from US 5 744 880 A, US 7 154 201 B2 and DE 39 41 474 A1.

[0005] An e-axle module generally includes a coolant circuit, which can be used to cool the components of the e-axle module, the electric motor, and possibly a transmission. The coolant returns via an external line in the form of a hose, a plastic pipe, or similar components. The disadvantage of externally mounted components is that additional components are required, such as lines, seals, and fixing components, which generate costs for procurement, assembly, documentation, and servicing. Furthermore, such solutions result in considerable additional effort for leak testing of the final product, as multiple sealing interfaces must be tested. The externally running plastic line or hose results in a greater installation space requirement.Furthermore, coolant lines running externally on the e-axis module, whether hoses or plastic pipes, adversely affect the appearance of this assembly. Description of the invention

[0006] The invention is defined by claim 1. Preferred embodiments emerge from the dependent claims.

[0007] According to the invention, a housing of an e-axle module is produced with at least one electric motor and a transmission, wherein the electric motor is cooled by means of a cooling circuit. In the housing, at least one cooling channel extends in at least one housing wall from a first transfer point to at least one further transfer point, running through the housing along thermally critical points.

[0008] This housing design advantageously allows external attachments for coolant lines or coolant line sections to be relocated to the interior, particularly in unobstructed, unused parts of the e-axis module's housing. This eliminates additional assembly and fastening costs and significantly reduces the number of required components.

[0009] The housing manufactured according to the invention comprises at least a first channel section and a further channel section, which are connected to each other at a deflection point. By appropriately routing the cooling channel through the housing or by selecting the number of cooling channel sections, optimal cooling of thermally critical areas can be ensured.

[0010] Advantageously, in the housing manufactured according to the invention, the thermally critical points are provided by a first bearing point and at least one further bearing point of the transmission. The bearing points on the transmission can be integrated into the path of the cooling medium due to appropriate routing of the at least one cooling channel along its extension through the at least one housing wall or in or on the housing shell, so that not only the waste heat from the electric machine but also the bearing temperature at the relevant bearing points can be kept constant or at a predetermined temperature.

[0011] In a further developed housing, the at least one cooling channel runs vertically in a housing wall and horizontally in or on a housing shell. By appropriately designing the routing of the at least one cooling channel, the requirements of automobile manufacturers regarding the arrangement of the transfer point on the housing of the e-axle module can be optimally accommodated, thus improving the installation flexibility of the e-axle module proposed according to the invention.

[0012] In a further embodiment of the housing, the at least one cooling channel is designed with regard to its line routing in such a way that it has bends on the at least one housing wall and in the housing shell, at which the cooling fluid flow can be deflected by 80° to 120°, in particular 90°.

[0013] In a further developed housing, at least one seal is provided at the at least one kink point of the cooling channel by means of a sealing body, in particular in the form of a steel ball.

[0014] In a further developed housing, the transfer points for the at least one cooling channel are integrated into the surface of the housing shell, so that no projections arise on it, which on the one hand improves its optical appearance and on the other hand represents a smooth surface.

[0015] In a further developed housing, the at least one cooling channel or its cooling channel sections are laid, in particular, through areas of the housing that are free of components. This allows for optimal use of the available installation space without the need for external attachments to the housing.

[0016] The invention relates to a method for producing the housing, wherein the at least one cooling channel or its cooling channel sections are created during the primary forming of the housing, in particular during die casting or casting of the housing, and the various cooling channel sections are finished with respect to diameter and length by machining in mutually different machining directions. Due to the subsequent machining of coolant channels or coolant sections previously created by a primary forming process, the cooling fluid volumes can be dimensioned accordingly, and furthermore, the line length can be optimally adapted to the coolant flow through the material, in particular the metallic material of the housing. Advantages of the invention

[0017] The design of the housing of an e-axle module proposed according to the invention makes it possible to avoid external attachments for cooling lines or cooling line sections. This reduces the number of components required and the assembly effort for the housing. Furthermore, the elimination of external attachments results in a more visually appealing appearance of the e-axle module as a fully assembled unit. Due to the specification of the transfer points, i.e. the connection points of the cooling channel to a cooling circuit, various requirements of automobile manufacturers can be taken into account, so that the positions of the transfer points can be created during the design of the housing, which is essentially produced using a primary forming process, for example by die casting.This allows the subsequent installation effort to be kept to a minimum, and furthermore the installation variance of the e-axle module proposed according to the invention can be significantly expanded with the correspondingly designed housing.

[0018] Finally, the method for manufacturing the housing proposed by the invention can significantly reduce the effort required for leak testing of coolant lines on the final product, i.e., on the finished e-axis module. Due to the reduction in the number of components, the risk of failure is significantly reduced when using the housing proposed by the invention on an e-axis module.

[0019] Furthermore, cost advantages arise in the procurement of assembly and documentation regarding parts lists and the like, supplier drawings, supplier support, and in the event of service. The installation space requirement is reduced because the cooling channel can largely be routed through the housing of the e-axis module manufactured according to the invention, and no external attachments are required. The fully assembled e-axis module offers visual advantages, as cooling fluid channels are only vaguely visible from the outside in the cast geometry of the housing. Short description of the drawings

[0020] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0021] They show: Figure 1 shows a perspective top view of a housing of an E-axis module, Figure 2 shows a side view of the housing of the E-axis module from the electric motor side, Figure 3 shows a side view of the housing of the E-axis module from the gearbox side, Figure 4 shows the course of channel sections of a cooling channel through the interior of the housing along thermally critical points, in particular bearing points in the gearbox, and Figure 5 shows a front view of the housing of the E-axis module with vertical and horizontal course of the cooling channel including the kink and seals provided there. Embodiments of the invention

[0022] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0023] Figure 1 shows a perspective view of the top of an e-axle module 10 of an electrically powered vehicle, for example an electrically powered passenger car or an electrically powered light commercial vehicle.

[0024] How Figure 1 As shown, the e-axis module 10 comprises a housing 12 in which an electric motor 11 (not shown in detail here) is installed. Furthermore, the e-axis module 10 comprises a transmission 13, also not shown in detail here. The housing 12 comprises a transmission side 14 and an opposite electric motor side 16, from which the electric motor 11 is inserted laterally into the interior of the housing 12, just as the transmission components of the transmission 13 are inserted into the housing 12 from the transmission side 14.

[0025] On the housing shell 58 of the housing 12 of the e-axle module 10, a first transfer point 18 of a cooling channel 24 and a second transfer point 20 of the cooling channel 24 are indicated. Also located on the housing shell 58 are flange domes 22, on which a housing of a power electronics unit or an inverter (not shown here for reasons of clarity) is received. The first transfer point 18 and the second transfer point 20 each represent the ends of the cooling channel 24, which extends in particular through the interior of a housing wall 26 of the housing 12 of the e-axle module 10. The housing wall 26 separates individual areas of the housing 12, which are provided for the transmission 13 and the electric machine 11, respectively. From the perspective view according to Figure 1It can be seen that on the gear side 14 of the housing 12 there is a circumferential sealing surface 28 on which individual threaded holes are provided, to which the cover of the gear 13 (not shown here) is mounted in order to seal the gear 13.

[0026] Figure 2 shows the view of the housing 12 from the electric motor side 16. The cooling channel 24 comprises in the illustration according to Figure 2a channel section 34 and a further channel section 36. The further channel section 36 opens into the said second transfer point 20. The channel section 34 extends through the interior of the housing 12 or the housing wall 26. Reference numerals 30 and 32 represent a first bearing point and a further bearing point for transmission components of the transmission 13. The installation space in the housing 12 of the e-axle module 10 is utilized by the at least one cooling channel 24, which extends through unused free spaces within the housing 12, so that it is possible to transition from an external line routing to a line routing of the at least one cooling channel 24 integrated into the housing 12.

[0027] Figure 3 shows the housing 12 from the gearbox side 14. In the top view according to Figure 3the individual flange bores can be seen, which are arranged in a regular arrangement along the sealing surface 28 on the gearbox side 14 of the housing 12 of the e-axle module 10. Figure 3 shows furthermore that, starting from the housing shell 58, the channel section 34 of the cooling channel 24 extends from the first transfer point 18 to a deflection point 38. At the deflection point 38, the channel section 34 of the at least one cooling channel 24 is connected to a further channel section 36. The further channel section 36 extends to the Figure 2 shown second transfer point 20. From the illustration according to Figure 3 It can be seen that, in particular, the channel section 34 extends through the interior of the housing wall 26 and is thus relocated into the interior of the housing 12 of the E-axis module 10. It should be emphasized that, according to the illustration in Figure 3the channel section 34 of the at least one cooling channel 24 extends along the first bearing point 30 and thus cools the rolling bearing provided there; the same applies to the further channel section 36, which is located in the immediate vicinity of the further bearing point 32 of the transmission 13. This ensures that a cooling effect can be achieved by the illustrated course of the channel sections 34, 36 of the at least one cooling channel 24 along thermally critical points, ie, rolling bearings on the transmission side arranged there at the bearing points 30 and 32 can be effectively cooled or kept at temperature by dissipating the waste heat.

[0028] Figure 4 It can be seen that the channel section 34, inclined essentially in the vertical direction, extends through the housing shell 58 of the housing 12 and merges into the said further channel section 36 at the deflection point 38. The Figure 4The channel sections 34 and 36 indicated can be prefabricated during the primary forming of the housing 12 to form the housing wall 26 or the housing shell 58 by means of a die-casting process or another casting process by providing corresponding cores. A final machining of the channel sections 34, 36 is carried out as in Figure 4indicated, in a first machining direction 40 and in a second machining direction 42, respectively. For this purpose, the channel sections 34, 36 can be machined in such a way that the diameter of the channel sections 34, 36 is drilled out to a defined width using suitable drills. Furthermore, corresponding lengths of the channel sections 34, 36 of the at least one cooling channel 24 can be produced in a defined manner using suitable tools by machining in the first machining direction 40 and in the second machining direction 42, so that the at least one cooling channel 24 can be adapted to the corresponding cooling fluid flow acting on it. The transfer points 18 and 20 arranged at the ends of the channel sections 34, 36 can be designed such that they are aligned with the surface of the housing shell 58, i.e.do not protrude significantly beyond these or are arranged in the form of nozzles so that the connections at the first transfer point 18 or the second transfer point 20 are located just above the housing shell 58 of the housing 12.

[0029] From the representation according to Figure 4 It is further apparent that the channel section 34 is located in the immediate vicinity of the first bearing point 30, while the further channel section 36 runs along the further bearing point 36. Due to the configuration or the routing of the channel sections 34, 36 of the at least one cooling channel 24 through the interior of the housing 12, the rolling bearings of the transmission components (not shown in detail here) arranged at the bearing points 30 and 32, respectively, can thus also be effectively tempered, i.e. cooled.

[0030] Figure 5shows a front view of the housing 12 of the E-axle module 10, on which a housing part is provided on the side to accommodate the gearbox 13. As in connection with Figure 1 As already explained, the housing 12 has the transmission side 14 and the electric motor side 16. From the illustration according to Figure 5 It can be seen that the housing wall 26 extends through the housing wall 26 between the part of the housing 12 which accommodates the electric machine 11, which is mounted from the electric machine side 16, and the gearbox side 14 of the housing 12, into which the gearbox 13 is installed from the gearbox side 14. In this extends, starting from the deflection point 38, as shown in the Figures 3 and 4 shown, the channel section 34. This has, as shown in Figure 5, has a substantially vertical profile 44. At a kink 48 above the housing shell 58 of the housing 12, the vertical profile 44 of the channel section 34 merges into a horizontal profile 46 of the cooling channel 24. At the kink 48, which can be integrated into the housing shell 58 or rests on it, there is a first seal 50 and a second seal 52. The first seal 50 and the second seal 52 make it possible to seal the kink 48 between the vertical profile 44 and the horizontal profile 46 of the cooling channel 24 in a manner that is simple to manufacture. For this purpose, sealing bodies 54 are used, which are preferably designed as steel balls 56. The first seal 50 and the second seal 52 are effectively sealed by the steel balls 56, so that the cooling medium does not escape from the at least one cooling channel 24, in particular not in the area of ​​the kink 48.For the sake of completeness, it should be mentioned that the flange domes 22 are located on the housing shell 58 of the housing 12, on which the power electronics, not shown in detail here, are accommodated on the housing 12.

[0031] By using the Figures 1 to 5 In the illustrated housing 12 of the e-axle module 10, the at least one cooling channel 24 can be routed through the interior of the housing 12 or through the housing shell 58 or through the housing wall 26 in the direction of the transfer points 18 and 20 required by the automobile manufacturer. This allows unused installation space inside the housing 12 to be utilized, resulting in space savings. In addition, thermally critical points in the form of the bearing points 30, 32 can be tempered by specifically routing the channel sections 34, 36 of the at least one cooling channel 24.

[0032] As already mentioned, the target diameter of the channel sections 34, 36 is created by machining following the primary forming process. The openings for the channel sections 34, 36 can already be provided in the cast blank design. Mechanical machining in the first machining direction 40 or in the second machining direction 42, which differs from this, is carried out using tools such as drills to create the corresponding line lengths of the channel sections 34, 36. Changes in direction of the channel sections 34, 36 can also be manufactured. The resulting deflection points 38 or the kink point 48 are sealed by pressing the sealing bodies 54 onto the first seal 50 or the second seal 52.

Claims

1. Method for producing a housing (12) of an E-axle module (10) having at least one electric machine (11) and a transmission (13), wherein the electric machine (11) is cooled by means of a cooling circuit, wherein, in the housing (12), at least one cooling channel (24) extends in at least one housing wall (26) from a first transfer point (18) to at least one further transfer point (20), the cooling channel running along thermally critical bearing points (30, 32), and wherein the at least one cooling channel (24) comprises at least one channel section (34) and a further channel section (36) which are fluidically connected to one another at a deflection point (38), characterized in that the method makes provision that the channel sections (34, 36) are produced during the primary shaping of the housing (12) and are finished in terms of diameter and length by machining in mutually different machining directions (40, 42).

2. Method according to Claim 1, characterized in that the thermally critical points are a first bearing point (30) and at least one further bearing point (32) of the transmission (13).

3. Method according to Claims 1 to 2, characterized in that the at least one cooling channel (24) takes a vertical profile (44) in the housing wall (26) and a horizontal profile (46) in or on a housing shell (58) of the housing (12).

4. Method according to Claims 1 to 3, characterized in that the at least one cooling channel (24) has, in the at least one housing wall (26) and in the housing shell (58), at least one kink (48) at which the cooling fluid flow is deflected in the range between 80° and 120°, preferably 90°.

5. Method according to Claim 4, characterized in that at least one seal (50, 52) is formed at the at least one kink (48) by means of a sealing body (54), in particular a steel ball (56).

6. Method according to Claims 1 to 5, characterized in that the transfer points (18, 20) lie in the area of the housing shell (58).

7. Method according to Claims 1 to 6, characterized in that the at least one cooling channel (24) or the channel sections (34, 36) thereof run through regions of the housing (12) which are free of internals.