Electric drive unit for motor vehicles

• US 20050245341A1
• Filed: 01/28/2005
• Published: 11/03/2005
• Est. Priority Date: 01/29/2004
• Status: Active Grant

• Current Assignee: RENK America LLC
• Original Assignee: Magnet-Motor Gesellschaft Fuer Magnetmotorische Technik MbH
• Inventors: Ehrhart, Peter, Mueller, Anton, Steffen, Jens, Walter, Fritz
• Granted Patent: US 7,214,155 B2
• Time in Patent Office: Days
• US Class Current: 475/5
• CPC Class Codes: B60K 11/06 with air cooling
• CPC Class Codes: B60K 17/046 with planetary gearing having orbital motion
• CPC Class Codes: B60K 2007/0038 the motor moving together with the wheel axle
• CPC Class Codes: B60K 2007/0092 the motor axle being coaxial to the wheel axle
• CPC Class Codes: B60K 7/0007 the motor being electric

Abstract

An electric drive unit for a motor vehicle comprises an electric motor having a motor housing, a stator mounted in the motor housing and having coil-wound poles, a rotor arranged internally of the stator with an air gap present between the stator and the rotor, and a planetary gear system having a sun wheel, a planet carrier, planet wheels and a ring gear. The planet wheels have a maximum diameter and axial positioning that an imaginary common envelope cylinder for all maximum diameters of the planet wheels is located radially inside of the winding heads present on one axial side of the stator and axially beside the portion of the rotor adjoining the air gap and that the planet wheels project in axial direction outwardly beyond said winding heads either not at all or with less than 50% of their tooth width in engagement with the sun wheel.

Claims

1. An electric drive unit for a motor vehicle, comprising:

(a) an electric motor having a motor housing fixed in non-rotatable manner;

(b) a stator of said electric motor, with the stator being mounted in the motor housing and having coil-wound poles;

(c) a rotor of the electric motor arranged internally of the stator, with an air gap being present between the pole faces of the stator and the outer periphery of the rotor facing said pole faces of the stator;

(d) a planetary gear system having a sun wheel, a planet carrier, planet wheels and a ring gear,

(e) the rotor of the electric motor and the sun wheel of the planetary gear system being coupled for torque transmission;

(f) a gear casing of the planetary gear system, the gear casing being attached to the motor housing or—

at least in part—

being an integral component part of the motor housing;

(g) as well as the feature that the planet wheels have such a maximum diameter and such axial positioning that an imaginary common envelope cylinder for all maximum diameters of the planet wheels is located radially inside of the winding heads present on one axial side of the stator as well as axially beside the portion of the rotor adjoining the air gap and that the planet wheels project in axial direction outwardly beyond said winding heads either not at all or with less than 50% of their tooth width in engagement with the sun wheel.

2. A drive unit according to claim 1,

characterized in that the ring gear of the planetary gear system is non-rotatable and the rotatable planet carrier is provided for transmission output.

3. A drive unit according to claim 1,

characterized in that the planet wheels are stepped planet wheels.

4. A drive unit according to claim 3,

characterized in that the stepped planet wheels have their small outer diameter project into a space of the rotor which is axially recessed from the face side of the rotor present at the portion of the rotor (10) adjoining the air gap.

5. A drive unit according to claim 1,

characterized in that there is provided a stub axle on which the motor housing is mounted and/or with which the motor housing—

at least in part—

forms an integral component; and

that the rotor is supported on the stub axle.

6. A drive unit according to claim 5,

characterized in that the sun wheel is an externally toothed hollow wheel having the stub axle extending therethrough.

7. A drive unit according to claim 5,

characterized in that a wheel carrier is rotatably supported on the stub axle in a position axially beside the electric motor and the planetary gear system.

8. A drive unit according to claim 7,

characterized in that the wheel carrier has a tire rim mounted thereon.

9. A drive unit according to claim 7,

characterized in that the sealing between a rotatable part on the output side of the planetary gear system and the gear casing is positioned at a location radially further outside than a bearing of the wheel carrier, with the sealing preferably not projecting beyond this bearing in axial direction.

10. A drive unit according to claim 1,

characterized in that a part of the motor housing containing the outer peripheral wall and a radially outer portion of an end wall, is adapted to be detached from the drive unit, so that the stator is detached as well and, preferably, a radially outer portion of the rotor is then adapted to be detached from the drive unit.

11. A drive unit according to claim 1,

characterized in that a portion of the rotor located on the other axial side of the rotor from the planetary gear system, is designed in the form of a drum of a drum brake.

12. A drive unit according to claim 11,

characterized in that the brake shoes of the drum brake are designed as an emergency supporting means of the rotor.

13. A drive unit according to claim 7,

characterized in that a frictional service brake of the drive unit is provided on the outside of the wheel carrier.

14. A drive unit according to claim 1,

characterized in that the electric motor is designed such that it can be utilized as service brake of the drive unit.

15. A drive unit according to claim 7,

characterized in that the axial dimension of the unit of electric motor and planetary gear system is at least 75% of the axial dimension of the tire rim, preferably 80 to 100%.

16. A drive unit according to claim 1,

characterized in that the torque transmission connection between the rotor and the sun wheel or the torque transmission connection between the planet carrier and a wheel carrier is adapted to be separated, preferably from the outside without unmounting.

17. A drive unit according to claim 1,

characterized in that the electric motor is a reluctance motor, preferably a reluctance motor with electronically controlled current supply.

18. A drive unit according to claim 17,

characterized in that the rotor of the reluctance motor is provided in addition with permanent magnets so as to increase the power density of the reluctance motor at higher speeds.

19. A drive unit according to any of claims 1,

characterized in that the stator is water-cooled.

20. A drive unit according to claim 1,

characterized in that the planetary gear system at least in part is cooled in that there is a thermally conductive connection to the motor housing and direct or indirect heat discharge is effected from there to the surroundings.

21. A drive unit according to claim 1,

characterized in that the rotor is air-cooled with air circulation, and in that the motor housing and/or the stator has a surface portion for taking up heat from the circulating air.

22. A drive unit according to claim 1,

characterized in that the bearings of the rotor and the planetary gear system and optionally the bearings of a wheel carrier are lubricated with oil in common.

23. A drive unit according to claim 1,

characterized by a connector element for establishing an electrical connection and/or a cooling liquid connection to the motor vehicle.

24. A motor vehicle,

characterized in that it is provided with a drive unit designed in accordance with claim 1.