Abstract
The invention relates to an electric drive (10) of an electrically driven vehicle. The electric drive (10) comprises a rotor (22) and a stator (24) which is enclosed by a housing (25). The housing (25) is formed by an outer part (48) and an inner part (50), each of which has an axial ribbing (62, 64) extending in an axial direction (78) of the housing (25).
Claims
1. An electric drive (10) of an electrically driven vehicle, the electric drive comprising a rotor (22) and a stator (24) which is enclosed by a housing (25), wherein the housing (25) is formed by an outer part (48) and an inner part (50), each of which has an axial ribbing (62, 64) extending in an axial direction (78) of the housing (25).
2. The electric drive (10) as claimed in claim 1, wherein the axial ribbings (62, 64), in the joined state of the outer part (48) and the inner part (50), form an intermediate space (60) through which the cooling medium flows substantially in a tangential direction.
3. The electric drive (10) as claimed in claim 1, wherein the outer part (48) has an inflow (42) and an outflow (44) for a cooling medium, wherein the inflow (42) and the outflow (44) are positioned at an axial distance (54) in relation to one another.
4. The electric drive (10) as claimed in claim 3, wherein the inflow (42) and the outflow (44) have an offset (52) in a circumferential direction relative to one another.
5. The electric drive (10) as claimed in claim 3, wherein the inflow (42) lies in a first axial plane (56) and the outflow (44) lies in a second axial plane (58), distanced therefrom in the axial direction (78).
6. The electric drive (10) as claimed in claim 1, wherein the axial ribbings (62, 64) are provided on demolding bevels (68) of the outer part (48) and inner part (50) of the housing.
7. The electric drive (10) as claimed in claim 1, wherein the outer part (48) and the inner part (50) of the housing (25) are provided in each case in a conicity (82).
8. The electric drive (10) as claimed in claim 1, wherein the axial ribbing (64) on an inner circumferential surface of the outer part (48) has a machined region (74).
9. The electric drive (10) as claimed in claim 1, wherein the axial ribbing (62) on a first outer circumferential surface of the inner part (50) has a machined region (74).
10. The electric drive (10) as claimed in claim 7, wherein the conicity (82) is determined by a first diameter (84) and a second diameter (86) of the inner part (50) of the housing (25).
11. The electric drive (10) as claimed in claim 1, wherein the stator (24) of the electric machine is fixed by a shrink connection (66) in the inner part (50) of the housing (25).
12. The electric drive (10) as claimed in claim 1, wherein the axial ribbing (62) of the inner part (50) of the housing (25) has interruptions (76), which impress a turbulent state on the flow (46) of the cooling medium.
13. An e-axle module of an electrically driven vehicle, the module comprising the electric drive (10) as claimed in claim 1.
14. The electric drive (10) as claimed in claim 1, wherein the axial ribbing (64) on an inner circumferential surface of the outer part (48) has a machined region (74) which is manufactured as a cylindrical overturn (71).
15. The electric drive (10) as claimed in claim 1, wherein the axial ribbing (62) on a first outer circumferential surface of the inner part (50) has a machined region (74) which is provided as a conical overturn (70).
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Embodiments of the invention are explained in greater detail with reference to the drawings and following description.
[0026] In the drawings:
[0027] FIG. 1 shows a perspective view of an electric drive with laterally flange-mounted transmission,
[0028] FIG. 2 shows a partial sectional illustration of the electric drive according to FIG. 1,
[0029] FIG. 3 shows a cooling medium flow at a housing proposed in accordance with the invention comprising an outer part and inner part,
[0030] FIG. 4 shows a plan view of an inner part, inserted into an outer part of the housing, with shrunken stator,
[0031] FIG. 5 shows a perspective view of the outer part of the housing,
[0032] FIG. 6 shows a first variant of an inner part with outer axial ribbing, and
[0033] FIG. 7 shows a second variant of the inner part with interruptions of the axial ribbing.
DETAILED DESCRIPTION
[0034] FIG. 1 shows a perspective view of an electric drive 10, which has a first endshield 12 and a second endshield 16. A motor housing 14 with laterally flange-mounted transmission 18 is arranged between the first endshield 12 and the second endshield 16. An electric machine, not shown in greater detail, of the electric drive 10 is received in the motor housing 14.
[0035] FIG. 2 shows that a rotor shaft 20, on which a rotor 22 of an electric machine is received, is mounted rotatably in a first bearing 26 and a second bearing 28. The rotor shaft 20 of the e-machine rotates relative to a stator 24, mounted fixedly on a housing, of an electric machine. The first bearing 26 is received in the first endshield 12. The second bearing 28 is mounted in the laterally flange-mounted transmission 18. The transmission 18 comprises an intermediate shaft 30, on which a gearwheel is received, which meshes with a drive pinion of the rotor shaft 20. Cooling channels 32 run in the motor housing 14. The individual cooling channels 32 are formed by separating webs 34 in the longitudinal direction. Each of the cooling channels 32 opens out into a first deflection pocket 36 or in a second deflection pocket 38, which are formed either in the first endshield 12 or in the material of the second endshield 16.
Embodiments of the Invention
[0036] In the following description of the embodiments of the invention, like or similar elements are denoted by like reference signs, wherein a repeated description of these elements is omitted in individual cases. The figures illustrate the subject matter of the invention merely schematically.
[0037] FIG. 3 shows a schematic illustration of a flow 46 of the cooling medium through a housing 25. The cooling medium enters a cooling system of the housing 25 via an inflow 42 and leaves said cooling system at an outflow 44. As can be seen from the illustration according to FIG. 3, the housing 25 is formed by an outer part 48 and an inner part 50. In the joined state, the outer part 48 and the inner part 50 define a channel geometry, as will be described hereinafter in further detail. It can be seen from FIG. 3 that the inflow 42 and the outflow 44 can be oriented in an offset 52 in a circumferential direction of, for example, 180° relative to one another. Offset angles deviating from 180° are also possible. Furthermore, the illustration according to FIG. 3 shows that an axial distance 54 is present between the inflow 42 and the outflow 44 for the cooling medium. Whereas the inflow 42 for the cooling medium lies in a first axial plane 56, the outflow 44 for the cooling medium is located in a second axial plane 58 further distanced from this first axial plane 56 in the axial direction. Due to the spacing between the inflow and outflow 42/44 for the cooling medium, a particularly long flow path can be specified for the cooling medium, so that the latter can transport away a maximum amount of heat from the electric drive 10. Alternatively, it is also possible to arrange the inflow 42 and the outflow 44 in one and the same axial plane.
[0038] It can also be deduced from the illustration according to FIG. 3 that a flow 46 of the cooling medium passes substantially in a tangential direction and splits after the inflow 42. Since the inflow 42 and the outflow 44 for the cooling medium, seen in the axial direction 78, are arranged far apart from one another, a flow around practically the entire housing 25 of the electric drive 10 is achieved. In principle, the inflow 42 and the outflow 44 could also be arranged in one and the same axial plane.
[0039] FIG. 4 shows that the inner part 50 is inserted into the outer part 48 of the housing 25 of the electric drive 10. An intermediate space 60 in the form of an annular gap is created between the outer part 48 on the one hand and the inner part 50 on the other hand. The geometry of the intermediate space 60 in the form of an annular gap is substantially flat, so that a large contact surface area results between the cooling medium and the surface to be cooled and heat can be transported optimally to the cooling medium. As shown in FIG. 4, the individual segments of the intermediate space 60 in annular gap form are formed on the one hand by the axial ribbing 62 of the inner part 50 and on the other hand by the axial ribbing 64 of the outer part 48. FIG. 4 furthermore shows that the stator 24 of the electric machine is shrunk in the inner part 50 by a shrink connection 66 and is thus fixed without the need for further fastening elements.
[0040] FIG. 4 also shows that the stator 24 of the electric machine encloses the rotor 22 of the electric machine, which is received on the rotor shaft 20.
[0041] FIG. 5 shows a perspective illustration of the outer part 48 of the housing 25. It is clear from the perspective illustration according to FIG. 5 that the outer part 48 of the housing 25 can be manufactured for example as a cast part, for example as an aluminum pressure die-cast part. For this purpose, the outer part 48 has demolding bevels 68. On account of the demolding bevels 68, the finished cast blank of the outer part 48 can be removed more easily from a casting mold or a casting tool. As also shown in FIG. 5, the outer part 48 comprises on its inner circumferential surface an axial ribbing 64 which consists of individual axial ribs spaced from one another in the circumferential direction and each comprising a base 72.
[0042] FIG. 5 also shows that the individual ribs of the axial ribbing 64 of the outer part 48 have a cylindrical overturn 71 within a machined region 74. Due to such a material-removing machining of the upper sides of the individual ribs of the axial ribbing 64 at the inner circumference of the outer part 48, the intermediate space 60 in the form of an annular gap in respect of the outer part 48 is defined.
[0043] Similarly to the illustration according to FIG. 5, the inner part 50 of the housing 25 shown in the illustration according to FIG. 6 has the axial ribbing 62 on its outer lateral surface. The individual ribs of the axial ribbing 62 on the outer circumference of the inner part 50 run substantially parallel to one another. As is also clear from the illustration according to FIG. 6, the inner part 50 of the housing 25, seen in the axial direction 78, is formed in a conicity 82. This means that the inner part 50 according to the illustration in FIG. 6, seen in the axial direction 78, is provided with a variable diameter, which extends in tapered fashion from a first diameter 84 to a second diameter 86. As also shown in FIG. 6, the stator 24 is fastened to an inner circumferential surface of the inner part 50 of the stator 24, for example via the shrink connection 66, shown in FIG. 4, between the stator 24 of the electric machine and the inner part 50 of the housing 25.
[0044] FIG. 6 also shows that the axial ribbing 62 of the inner part 50 of the housing 25 has a machined region 74. The machined region 74 of the axial ribbing 62 of the inner part 50 is provided with a conical overturn 70. Within the conical overturn 70, the upper edges of the individual ribs of the axial ribbing 62 are machined with material removal, i.e. are ground down.
[0045] When joining the inner part 50 to the outer part 48 of the housing 25 shown in FIG. 5, the intermediate space 60 in the form of an annular gap shown in FIG. 4 is created, within which the cooling medium flows tangentially (see position 46 in the illustration according to FIG. 3).
[0046] FIG. 7 shows an alternative design option for the inner part 50 of the housing 25. According to the illustration in FIG. 7, the inner part 50 comprises an end face 80. At the outer circumference of the inner part 50, there runs the axial ribbing 62, which extends substantially in the axial direction 78. The individual ribs of the axial ribbing 62 of the inner part 50 have individual interruptions 76. The individual interruptions 76 of an individual rib of the axial ribbing 62 of the inner part 50 according to the illustration in FIG. 7 align with interruptions 76 of adjacent individual ribs of the axial ribbing 62. Grooves 88 are thus created, which extend in the circumferential direction of the inner part 50 and impress a turbulent flow state on the cooling medium as it passes through an arrangement formed of the outer part 48 and inner part 50. Due to the turbulent flow state of the cooling medium, which flows through the intermediate space 60 in the form of an annular gap in accordance with the flow 46 according to FIG. 3, an improved dissipation of heat from the housing 25 of the electric drive 10 proposed in accordance with the invention is provided.
[0047] Due to the variant of the inner part 50 according to FIG. 7, there is a significant enlargement of the surface and an impression of a turbulent flow state in relation to the cooling medium which flows through the intermediate space 60 in the form of an annular gap between the outer part 48 on the one hand and the inner part 50 of the housing 25 on the other hand.
[0048] The invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, a multitude of modifications which lie within the capabilities of a person skilled in the art are possible within the scope stated by the claims.
