Electrically operable drive train

Abstract

An electrically operable drive train of a motor vehicle, including an electric motor and a transmission arrangement, in which drive train the electric motor and the transmission arrangement form a structural unit, and the structural unit includes a first housing part and a second housing part, the first housing part and/or the second housing part having fastening means which bring about predefined positioning of the first housing part relative to the second housing part, and the first housing part is formed from a metal material, the second housing part being shaped from a plastics material by means of primary shaping processes, in particular by means of an injection moulding process, and having at least one insert part which is surrounded by plastics material in such a way that it is arranged in the second housing part such that it transmits axial and/or radial force and/or torque.

Claims

1. An electrically operable drive train for a motor vehicle comprising: an electric machine and a transmission arrangement, the electric machine and the transmission arrangement form a structural unit, and the structural unit includes a first housing part and a second housing part fastened together with fasteners which bring about a predefined positioning of the first housing part relative to the second housing part, and the first housing part is a metal part, wherein the second housing part is a molded plastic part, and has at least one insert part surrounded by plastic and arranged in the second housing part such that it transmits axial and/or radial force and/or torque, wherein the insert part has a specific damping stiffness of between >=1,500 kN*cm/g and <=25,000 kN*cm/g, and the second housing part has a specific damping stiffness of between >=20 kN*cm/g and <1,800 kN*cm/g, wherein the at least one insert part includes an internally toothed ring gear and a ring-like insert part against which the ring gear rests axially at least in sections, and wherein the ring gear abuts the insert part only within the root circle radius of the ring gear.

2. The electrically operable drive train according to claim 1, wherein the plastic of the second housing part is fiber-reinforced and an average fiber length of the fibers is between >=0.1 and <=50 mm.

3. The electrically operable drive train according claim 1, wherein the insert part is fiber-reinforced and an average fiber length of the fibers is between >50 mm and <=860 mm.

4. The electrically operable drive train according to claim 1, wherein the second housing part is a housing cover.

5. The electrically operable drive train according to claim 1, wherein the at least one insert part further includes a reinforcement.

6. The electrically operable drive train according to claim 5, wherein the reinforcement comprises a fastener for fastening the second housing part to a drive train suspension.

7. The electrically operable drive train according to claim 1, wherein the at least one insert part further includes a sleeve through which a fastener extends.

8. The electrically operable drive train according to claim 1, wherein in the second housing part at least one sensor is at least partially surrounded by plastic.

9. The electrically operable drive train according to claim 1, wherein the ring-like insert has a U-shaped cross-section.

10. An electrically operable drive train for a motor vehicle comprising: an electric machine and a transmission arrangement, the electric machine and the transmission arrangement form a structural unit, and the structural unit includes a first housing part and a second housing part fastened together with fasteners which bring about a predefined positioning of the first housing part relative to the second housing part, and the first housing part is a metal part, wherein the second housing part is a molded plastic part, and has at least one insert part surrounded by plastic and arranged in the second housing part such that it transmits axial and/or radial force and/or torque, wherein the insert part has a specific damping stiffness of between >=1,500 kN*cm/g and <=25,000 kN*cm/g, and the second housing part has a specific damping stiffness of between >=20 kN*cm/g and <1,800 kN*cm/g, wherein the at least one insert part includes an internally toothed ring gear and a ring-like insert part against which the ring gear rests axially at least in sections, wherein the ring-like insert has a U-shaped cross-section, and wherein the ring gear abuts a first free leg of the U-shaped insert part only within a root circle radius of the ring gear.

11. The electrically operable drive train according to claim 10, wherein a second free leg of the U-shaped cross-section of the ring-like insert that is not in contact with the ring gear and runs in the radial direction is longer than the first free leg of the U-shaped cross-section of the ring-like insert that is in contact with the ring gear.

12. The electrically operable drive train according to claim 11, wherein the second free leg extends radially inwards and has a radius that is greater than or equal to the tip circle radius of the ring gear.

13. The electrically operable drive train according claim 10, wherein the insert part is fiber-reinforced and an average fiber length of the fibers is between >50 mm and <=860 mm.

14. The electrically operable drive train according to claim 10, wherein the second housing part is a housing cover.

15. The electrically operable drive train according to claim 10, wherein the at least one insert part further includes a reinforcement.

16. The electrically operable drive train according to claim 15, wherein the reinforcement comprises a fastener for fastening the second housing part to a drive train suspension.

17. The electrically operable drive train according to claim 10, wherein the at least one insert part further includes a sleeve through which a fastener extends.

18. The electrically operable drive train according to claim 10, wherein in the second housing part at least one sensor is at least partially surrounded by plastic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the figures:

(2) FIG. 1 shows a first embodiment of the electrically operable drive train in a coaxial configuration,

(3) FIG. 2 shows a first embodiment of a housing cover in a perspective view,

(4) FIG. 3 shows a second embodiment of a housing cover in a perspective view,

(5) FIG. 4 shows a reinforcement in a perspective view,

(6) FIG. 5 shows a motor vehicle with electrically operable drive trains, and

(7) FIG. 6 shows a first embodiment of a housing cover in an axial sectional view.

DETAILED DESCRIPTION

(8) FIG. 1 shows a first embodiment of an electrically operable drive train 1 of a motor vehicle 2 comprising an electric machine 3 and a transmission arrangement 4, the electric machine 3 and the transmission arrangement 4 forming a structural unit 5. This is shown as an example in FIG. 5. The left axle of the motor vehicle 1 is provided with a coaxial design of an electrically operable drive train 1, while the right axle shows an axially parallel design of an electrically operable drive train 1. This is discussed in more detail below.

(9) The structural unit 5 shown in FIG. 1 corresponds to a coaxial design. The structural unit 5 has a first housing part 6 in which an electric machine 3 and a transmission arrangement 4 are arranged. In the exemplary embodiment shown, the first housing part 6 is made from die-cast aluminum. The structural unit also has a second housing part 7 designed as a housing cover 13, with the first housing part 6 and the second housing part 7 having fastening means 8 in the form of screws and corresponding internal threads, as a result of which a predefined positioning of the first housing part 6 relative to the second housing part 7 is brought about.

(10) The second housing part 7 is formed from a plastic by means of a primary molding process, in particular by means of an injection molding process. The second housing part 7 has at least one insert part 9, which is surrounded by plastic in such a way that it is arranged in the second housing part 7, which is designed as a housing cover 13, such that it transmits axial and radial forces and torque. This can be seen particularly well in the illustration in FIG. 2. In the exemplary embodiment of a second housing part 7 shown in FIG. 2, the insert part 9 is designed as an internally toothed ring gear 10 for a planetary gearing.

(11) FIG. 6 shows a cross-sectional view of the second housing part 7 known from FIGS. 2 and 3. This representation clearly shows that the ring gear 10 is overmolded axially on both sides by the plastic of the second housing part 7.

(12) In order to improve the axial fixing of ring gear 10 and in particular the absorption of axial forces, an additional ring-like insert part 18 with a U-shaped cross section can be arranged in second housing part 7, against which the ring gear 10 rests axially at least in sections. The free leg of the U-shaped insert part 18 lying axially on the ring gear 10 and running in the radial direction is configured in such a way that it only bears within the root circle radius of the ring gear 10. In the exemplary embodiment shown in FIG. 6, the free leg of the U-shaped insert part 18 that is not in contact with the ring gear 10 and runs in the radial direction is longer than the free leg that is in contact with the ring gear 10. It extends radially inwards, the radius of which is greater than or equal to the tip circle radius of the ring gear 10.

(13) The U-shaped insert part 18 thus also enables the injection molding tool to be configured in a way that is favorable in terms of production technology, by means of which the second housing part 7 is manufactured. In particular, demolding is simplified in the embodiment shown in FIG. 6, since the second housing part 7 has no injection-molded undercuts due to the U-shaped insert part.

(14) In principle, the U-shaped insert part 18 can also have other cross-sectional contours, such as V, W, N, C, O, X, Z, or S-shaped cross-sectional contours. Such an insert part can in principle be used to increase the force absorption, in particular for axial and/or radial force absorption.

(15) Furthermore, a roller bearing 14 is arranged as an insert part 9 in the second housing part 7. The roller bearing 14 has a diameter that is smaller than the diameter of the ring gear 10 and smaller than the smallest diameter of the insert part 18.

(16) The roller bearing 14 is also overmolded axially on both sides by the plastic of the second housing part 7. As with the ring gear 10, an insert part 9 can also be provided for the roller bearing 14 to increase the axial and/or radial force absorption. For this purpose, an insert part 20 with an L-shaped cross section is provided in the second housing part 7, with the roller bearing 14 being supported axially on the radially extending section of the L-shaped insert part 20. It would also be possible to arrange a further bearing, for example a roller bearing or sliding bearing, on the axially running section of the L-shaped insert part 20, but this is not shown in FIG. 6. In the embodiment shown, the second housing part 7 can also assume the function of an A or B end shield of the electric machine.

(17) The second housing part 7 also has on its radially outer lateral surface fastening sections 19 which protrude radially outwards and by means of which the second housing part 7 can be fixed on the first housing part 6. For this purpose, an insert part 9 in the form of a metal sleeve 17 is provided in a fastening section 19, through which a fastening means 8here a screwengages.

(18) The insert parts 9 have a specific damping stiffness between >=1,500 kN*cm/g and <=25,000 kN*cm/g, preferably between >=1,800 kN*cm/g and <=15,000 kN*cm/g and the housing part 7 has a specific damping stiffness between >=20 kN*cm/g and <1,800 kN*cm/g, preferably between >=200 kN*cm/g and <1,500 kN*cm/g.

(19) FIG. 3 shows a second housing part 7 configured as a housing cover 13, which is configured for use in an axially parallel structure of the structural unit 5. The insert part 9 is designed as a reinforcement 11 in the embodiment shown in FIG. 3. The reinforcement 11 has three axially parallel, circular bearing seats 12, on which a bearing, in particular a roller bearing 14 or sliding bearing, can be positioned. The reinforcement 11 is shown again in FIG. 4 in an isolated view.

(20) The reinforcement 11 can have fastening openingswhich is not shown in FIGS. 3-4which are penetrated by the fastening means 8such as screwsin order to affix the second housing part 7 to the first housing part 6.

(21) The bearing seats 12 are each formed as a ring 15 with a lateral surface 16 running in the axial direction, the ring 15 having a section protruding from its lateral surface in the radial direction. In the exemplary embodiment shown, these sections are connected to one another in one piece in one plane to form the reinforcement 11. The lateral surfaces 16 running in the axial direction extend out of the reinforcement 11 in different axial directions.

(22) The disclosure is not limited to the embodiments shown in the figures. The above description is therefore not to be regarded as limiting, but rather as illustrative. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the disclosure. This does not exclude the presence of further features. If the patent claims and the above description define first and second features, this designation serves to distinguish between two features of the same type without defining an order of precedence.

LIST OF REFERENCE SYMBOLS

(23) 1 Drive train 2 Motor vehicle 3 Machine 4 Transmission arrangement 5 Unit 6 Housing part 7 Housing part 8 Fastening means 9 Insert part 10 Ring gear 11 Reinforcement 12 Bearing seat 13 Housing cover 14 Rolling bearing 15 Ring 16 Lateral surface 17 Sleeve 18 Insert part 19 Fastening section 20 Insert part