Electric motor having a contact point on a housing for a ground cable

Abstract

An electric motor for an adjusting device of a motor vehicle, particularly of a gearbox actuator, has a stator energized by an electronic mechanism and a rotor for powering the motor. The stator is disposed in a metallic stator housing on which a contact point for connecting an earth cable is integrally shaped.

Claims

1. An electric motor for an adjusting drive of a motor vehicle, the electric motor comprising: a metal stator housing having an end face; a ground cable; a contact point connected to said ground cable and formed from said metal stator housing as an integrated one-piece part with said metal stator housing, said contact point is disposed on said end face of said metal stator housing and said contact point relative to an outer diameter of said metal stator housing is radially offset toward an inside; a electronic assembly, said ground cable is integrated into said electronic assembly; and a stator supplied with an electric current by said electronic assembly and disposed in said metal stator housing.

2. The electric motor according to claim 1, wherein said contact point is a bent connection lug that is stamped out of said metal stator housing.

3. The electric motor according to claim 1, wherein said end face has a connection unit for bringing said stator into contact with said electronic assembly.

4. The electric motor according to claim 3, wherein said electronic assembly is attached to said end face and is screwed to said end face.

5. The electric motor according to claim 1, further comprising a rotor having a single shaft extension disposed within said stator and said single shaft extension protruding out of a further end face of said metal stator housing that lies opposite said end face of said metal stator housing.

6. The electric motor according to claim 1, wherein said ground cable is mounted onto said contact point.

7. The electric motor according to claim 1, wherein said ground cable is one of soldered or welded to said contact point.

8. The electric motor according to claim 1, wherein said contact point is bent outward.

9. A transmission actuator of a motor vehicle, comprising: a ground cable; an electric motor containing a metal stator housing having an end face, a contact point connected to said ground cable formed from said metal stator housing as an integrated one-piece part with said metal stator housing, a electronic assembly, and a stator supplied with an electric current by said electronic assembly and disposed in said metal stator housing; said contact point is disposed on said end face of said metal stator housing and said contact point relative to an outer diameter of said metal stator housing is radially offset toward an inside; and said ground cable is integrated into said electronic assembly.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) An exemplary embodiment of the invention is further explained hereinunder with reference to a drawing. In the drawings:

(2) FIG. 1 illustrates schematically a simplified illustration of a powertrain of a motor vehicle,

(3) FIG. 2 illustrates the electric motor in perspective,

(4) FIG. 3 illustrates schematically a simplified illustration of a stator housing of the electric motor in a plan view, and

(5) FIG. 4 illustrates the electric motor in a sectional view in accordance with FIG. 3.

DESCRIPTION OF THE INVENTION

(6) Corresponding parts are provided with identical reference numerals in all figures.

(7) FIG. 1 illustrates schematically a simplified illustration of a powertrain 2 of a motor vehicle. An internal combustion engine 4 is in operative contact with drive wheels 12 by way of a first shaft 6, a transmission 8, a second shaft 10 and a differential (not illustrated). The rotational movement of the first shaft 6 that is directly driven by the internal combustion engine 4 is converted into a rotational movement of the drive wheels 12, wherein both the direction of rotation and also the rotation speeds of the two differ. The rotational movement essentially occurs at a right angle with respect to rotational movement of the second shaft 10 as a result of the differential.

(8) A specific transmission ratio between the first shaft 6 and the second shaft 10 is determined by means of the transmission 8. In addition, the direction of rotation of the second shaft 10 is set by means of the transmission 8. For this purpose, the transmission comprises a number of so-called switching stages that are selected by means of a transmission actuator 16 that comprises an electric motor 14. The electric motor 14 drives an adjusting part of the transmission actuator 16 that in turn is operatively connected to a selecting mechanism of the transmission 8. In addition, the transmission actuator 16 comprises an electronic control assembly (not illustrated) that controls the electric motor 14 and that is set by a selection lever 20 by way of a data line 18. The data line 18 is a CAN-bus and a driver can select the direction of movement of the motor vehicle by means of the selection lever 20.

(9) FIG. 2 illustrates in perspective a stator housing 22 of the electric motor 14. The stator housing 22 is stamped out of a metal and is bent into shape. The stator housing 22 comprises a cylindrical form having an essentially round base surface. The stator housing 22 is encompassed on the outer periphery by the mounting ring 24. In other words, the stator housing 22 is inserted into the mounting ring 24 and is held by the mounting ring in a positive locking or non-positive locking connection.

(10) A connection unit 28 is located on an end face 26, also described as a bearing plate, of the cylinder shaped stator housing 22. The connection unit 28 comprises three connection points 28a, 28b, 28c that are electrically in electrical contact with field windings 29 of a stator 30 that is further illustrated in FIG. 4. A rotating magnetic field is generated by means of the field windings 29 and said magnetic field sets a rotor 32 that is likewise illustrated in FIG. 4 into a rotating movement. For this purpose, the field windings 29 are mutually connected in a so-called delta connection. The connection points 28a, 28b, 28c protrude through the openings 34 that are provided in the end face 26 of the stator housing 22. These rectangular-shaped openings 34 are stamped into the end face 26 during production of the stator housing 22. A U-shaped contour 36a is stamped into the end face 26 in the same production step. The resulting material tongue is bent towards the exterior in other words away from the interior of the stator housing 22 for the purpose of forming a bent connection lug and forms a contact point 36. The contact point 36 is consequently embodied as one part with the stator housing 22.

(11) The stator housing 22 and the electric motor 14 are illustrated schematically and in a simplified illustration in FIG. 3 and FIG. 4 in a plan view and a cross sectional view along the cylinder axis of the cylindrical stator housing 22, said cylinder axis coinciding with an axis of rotation 38 of the electric motor 14. The embodiment of the stator housing 22 differs in this case from that illustrated in FIG. 2. The three connection points 28a, 28b, 28c are located on one side of the axis of rotation 38 and are not distributed around this axis in a rotationally symmetrical manner. Two ball bearings 40 are pressed into the stator housing 22 within which a shaft 42 of the rotor 32 is mounted in a rotatable manner. One of the ball bearings 40 is arranged flush with the end face 26. The other ball bearing 40 is located in a specific contour that is integrated in the end face 44 of the stator housing 22, said end face lying opposite the end face 26. A shaft extension 46 protrudes on this end face 44 out of the stator housing 22. The shaft extension 46 describes the particular part of the shaft 42 to which is fastened the adjusting part of the motor vehicle, said adjusting part being driven by means of the electric motor 14.

(12) A rotor laminated core 48 is fastened to the shaft 42 and said rotor laminated core receives a number of permanent magnets 50. A magnetic field is formed between said magnets and the stator 30 during the operation of the electric motor 14 and said magnetic field sets the rotor 32 in a rotational movement about the axis of rotation 38. For this purpose, the field windings 29 that are wound around the stator laminated core 52 are supplied with an electric current by way of the connection unit 28.

(13) An electronic assembly 54 that in this case is only illustrated in part is attached to the end face 26 and is screwed into the stator housing 22. A number of conductor tracks 56 are integrated in the electronic assembly 54 and said conductor tracks supply the coil windings 29 with electrical energy by way of the respective connection points 28a, 28b, 28c. The electrical contact between the conductor rails 56 and the connection unit 28 is provided by means of soldering, clamping or a specifically produced stamped bent sheet part.

(14) In addition, a ground cable is integrated in the electronic assembly 54, said ground cable being electrically connected to ground, in other words to the motor vehicle bodywork. The ground cable 58 is mounted on the contact point 36 and is soldered to said contact point. The stator housing 22 is therefore electrically connected to ground by way of the ground cable 58 which prevents a static charge build-up on the stator housing 22 during the operation of the electric motor. In addition, components of the electronic assembly 54 are in electrical contact with the ground cable 58, as a result of which an electrical field does not likewise form between the electronic assembly 54 and the stator housing. In the case of assembling the electronic assembly 54 on the stator housing 22, both the ground cable 58 and also the conductor rails 56 are electrically contacted by the contact point 36 or rather the connection unit 28 in one production step. In this manner, a comparatively rapid assembly of the electric motor is rendered possible.

(15) The invention is not limited to the above described exemplary embodiment. On the contrary, other variants of the invention can also be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, in addition, all the individual features that are described in relation to the exemplary embodiment can also be mutually combined in another manner without departing from the subject matter of the invention.

LIST OF REFERENCE NUMERALS

(16) 2 Powertrain

(17) 4 Internal Combustion Engine

(18) 6 First Shaft

(19) 8 Transmission

(20) 10 Second Shaft

(21) 12 Drive Wheels

(22) 14 Electric Motor

(23) 16 Transmission Actuator

(24) 18 Data Line

(25) 20 Selection Lever

(26) 22 Stator Housing

(27) 24 Mounting ring

(28) 26 End face

(29) 28 Connection Unit

(30) 28a Connection Point

(31) 28b Connection Point

(32) 28c Connection Point

(33) 29 Field Winding

(34) 30 Stator

(35) 32 Rotor

(36) 34 Opening

(37) 36 Contact Point

(38) 36a U-contour

(39) 38 Axis of Rotation

(40) 40 Ball Bearing

(41) 42 Shaft

(42) 44 End Face

(43) 46 Shaft Extension

(44) 48 Rotor Laminated Core

(45) 50 Magnet

(46) 52 Stator Laminated Core

(47) 54 Electronic Assembly

(48) 56 Conductor Tracks

(49) 58 Ground Cable