Transmission unit

Abstract

A transmission unit of a motor vehicle, with a transmission having a transmission shaft and with an electric motor that is coupled thereto in an axial direction and that has a stator and that has a rotor arranged on a motor shaft and that is bearingless on the A-side. The electric motor includes an end plate on the B-side, and the stator is located at least partly inside a housing of the transmission.

Claims

1. A transmission unit of a motor vehicle, the transmission unit comprising: a transmission having a transmission shaft; an electric motor that is coupled to the transmission in an axial direction, the electric motor having a stator and a rotor arranged on a motor shaft; a motor bearing supporting the motor shaft; and an electronic drive unit facing an end surface of a transmission housing, wherein the electric motor is bearingless on an a first side, wherein the electric motor has an end plate on a second side, wherein the motor bearing is attached to the end plate, and wherein the stator is arranged at least partly inside the transmission housing, wherein an opening is disposed between the electronic drive unit and the end surface, wherein the end plate is mounted on the end surface in the opening between the end surface and the electronic drive unit, and wherein at least a portion of the stator is not enclosed.

2. The transmission unit according to claim 1, wherein a portion of the stator that is located inside the transmission housing is at least partly enclosed in a form-fitting manner by a corresponding recess of the transmission housing.

3. The transmission unit according to claim 2, wherein the recess is stepped and rests against a housing of the motor on a circumference thereof.

4. The transmission unit according to claim 1, wherein the transmission shaft and the motor shaft are placed one inside the other, and wherein corresponding structures of the motor and transmission shafts engage one another.

5. The transmission unit according to claim 4, wherein the motor shaft accommodates a facing shaft end of the transmission shaft, and wherein, in this region, the motor shaft is internally toothed and the transmission shaft is externally toothed.

6. The transmission unit according to claim 1, wherein the stator has a frustoconical insulating ring with a central opening on a free end at the transmission side.

7. The transmission unit according to claim 1, wherein the electric motor is fastened to the transmission housing via a screw or rivet extending through a mounting lug of the end plate, and wherein the end plate rests at least partially on the transmission housing.

8. The transmission unit according to claim 1, wherein the electronic drive unit is fastened to the electric motor via a screw or rivet extending through a mounting lug of the end plate.

9. An electric motor of a motor vehicle actuator, in particular of a transmission unit according to claim 1.

10. The transmission unit according to claim 1, wherein the motor bearing is a single bearing supporting the motor shaft.

11. The transmission unit according to claim 1, wherein the motor shaft is supported by only a single bearing, the single bearing comprising the motor bearing.

12. The transmission unit according to claim 1, wherein the motor shaft is parallel to the transmission shaft.

13. The transmission unit according to claim 1, wherein the motor shaft is coupled to the transmission shaft.

14. The transmission unit according to claim 1, wherein the transmission shaft has a plurality of uniformly spaced external teeth that mesh with corresponding teeth disposed on a recess of the motor shaft.

15. The transmission unit according to claim 1, wherein the end plate comprises: a curved body; a hole through which the motor shaft extends; a plurality of first mounting portions for mounting the end plate to the transmission housing; and a plurality of second mounting portion for mounting the electronic drive unit to the end plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 is a drive train of a motor vehicle in a simplified schematic view,

(3) FIG. 2 is a cross-sectional representation along an axial direction of a transmission unit, and

(4) FIG. 3 is a perspective view of an electric motor of the transmission unit.

DETAILED DESCRIPTION

(5) In FIG. 1 a simplified schematic view of a drive train 2 of a motor vehicle is shown. An internal combustion engine 4 stands in operative connection with drive wheels 12 through a first shaft 6, a transmission unit 8, a second shaft 10, and a differential that is not shown. In this arrangement, the rotational motion of the first shaft 6, which is driven directly by the internal combustion engine 4, is converted into a rotational motion of the drive wheels 12, with both the direction of rotation and the rotational speeds of the two being different. Because of the differential, the rotational motion of the drive wheels 12 takes place essentially at a right angle to the rotational motion of the second shaft 10.

(6) By means of a transmission 14 of the transmission unit 8, a torque provided by the internal combustion engine 4 is transmitted variably to the drive wheels 12. For this purpose, the transmission 14 has a clutch that is operated by means of a transmission actuator 18 that includes an electric motor 16. The transmission actuator 18 additionally has an electronic drive unit 20 that controls the electric motor 16. The electronic drive unit 20 is adjusted by a gearshift lever 24 via a data line 22. The data line 22 is a CAN bus, and a driver can, using the gearshift lever 24, select whether and how many of the drive wheels 12 are supplied with the torque provided by the internal combustion engine 4.

(7) FIG. 2 shows the transmission unit 8 in a cross-sectional representation along an axial direction 26, wherein the axial direction 26 corresponds to the longitudinal direction of a cylindrical motor shaft 28 of the electric motor 16 and to the longitudinal direction of a cylindrical drive shaft 30 of the transmission 14. In other words, the motor shaft 28 is parallel to the transmission shaft 30 and to the axial direction 26. The two shafts 28, 30 are aligned such that the axis of rotation of the motor shaft 28 coincides with the axis of rotation of the transmission shaft 30.

(8) The two shafts 28, 30 are coupled to one another, wherein the shaft end 32 of the motor shaft 28 that faces the transmission shaft 30 is made hollow and accommodates within itself the shaft end 34 of the transmission shaft 30 that faces the motor shaft 28. In other words, the two shafts 28, 30 are placed one inside the other. In order to effectively transfer a rotary motion of the motor shaft 28 into a rotary motion of the transmission shaft 30, the transmission shaft end 34 is designed to be externally toothed. In other words, the transmission shaft end 34 has on its circumference a number of uniformly spaced teeth 36 that mesh with corresponding teeth 36 formed on the cavity-like recess of the motor shaft end 32 on the motor shaft 28.

(9) The assembly formed from the motor shaft 28 and the transmission shaft 30 is rotatably mounted by means of two transmission bearings 38 and one motor bearing 40. The two transmission bearings 38 are arranged within a transmission housing 42 of the transmission 14, in which transmission elements that are not shown in detail here, for example gears, are also accommodated. The transmission housing 42 itself is made of metal.

(10) The motor bearing 40 is press-fitted into a B-side end plate 44 of the electric motor 16 made of sheet metal. The B-side end plate 44 in this design is located on the side of the electric motor 16 opposite the transmission 14. Consequently, a rotor 46 located on the motor shaft 28 and a stator 48 standing in operative connection therewith are located between the motor bearing 40 and the transmission bearings 38. The electric motor 16 is thus of bearingless design on the A-side, with an A-side end plate also being absent. The stator 48 is supplied with current by means of the electronic drive unit 20, which rests on the end plate 44 and is fastened there. For this purpose, the end plate 44 has a number of second mounting lugs 50 through which screws 52 are inserted and are screwed into corresponding receptacles in the electronic drive unit 20. The electronic drive unit 20 in this design includes a number of semiconductor elements that are connected to form a bridge circuit.

(11) The end plate 44 also has a number of first mounting lugs 54, through which a corresponding number of screws 56 are inserted, wherein the screws 56 are screwed into the transmission housing 42. In this arrangement, the end plate 44 rests on the transmission housing 42 in order to avoid tilting of the electric motor 16 relative to the transmission 14, and consequent bending of the shaft assembly 28, 30 due to an increased lever arm. For the purpose of stabilization, the electric motor 16 is located partially within the transmission housing 42, shortening the installation space of the transmission unit 8 in the axial direction 26. To this end, the stator 48 is partially inserted in a stepped recess 58 of the transmission housing 42. In the region of its reduced diameter, the recess 58 contacts the stator 48 in a form-fitting manner. In the region of increased diameter, which is to say behind the step, a hollow, cylindrical motor housing 60 is located between the stator 48 and the transmission housing 42. The motor housing 60 made from sheet metal encloses the stator 48 in a form-fitting manner in the associated area, and is attached to the B-side end plate 44. The recess 58 of the transmission housing 42, in turn, encloses the motor housing 60 in a form-fitting manner.

(12) An insulating ring 62 made of a rubber is located on the stator 48 on the side facing the transmission 14, as is also shown in FIG. 3. This figure shows the electric motor 16 with installed electronic drive unit 20, but without the transmission 14, which are components of an actuator 64 of the motor vehicle. The insulating ring 62 has the shape of a frustum of a cone, wherein the outer diameter of the insulating ring 62 decreases with increasing distance from the end plate 44. The axis of the frustoconical insulating ring 62 coincides with the axis of rotation of the motor shaft 28. A central opening 66 through which the rotor 46, which has a number of permanent magnets, can be introduced into the electric motor 16 is provided in the insulating ring 62. By means of the insulating ring 62, the entry of foreign particles through the recess 58 into the region of the rotor 46 is prevented in the assembled state. In addition, the insulating ring 62 serves as a positioning aid during assembly of the transmission unit 8, since tilting of the stator 48 on the step of the recess 58 can be avoided therewith.

(13) The invention is not limited to the exemplary embodiment described above. Rather, other variants of the invention can also be derived herefrom by a person skilled in the art without departing from the subject matter of the invention. In particular, moreover, all individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention.

(14) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.