Electric motor comprising an integrated rotary encoder

Abstract

An electric motor has an end shield and a sensor for detecting a magnetic field. The sensor is integrated into the end shield of the electric motor. An electric drive unit may include a brake, in particular an electromagnetically actuatable brake, and an electric motor, where a shielding element is arranged between the sensor and the brake.

Claims

1. An electric drive unit, comprising: a brake; an electric motor having an end shield and having a sensor that senses a magnetic field and is integrated into the end shield of the electric motor; and a shielding element arranged between the sensor and the brake, wherein a surface of the shielding element that faces toward the brake forms a friction surface of the brake.

2. The electric motor as claimed in claim 1, wherein the electric motor has an encoder element, connected in a rotationally fixed manner to a shaft of the electric motor, for generating a magnetic field that can be sensed by the sensor.

3. The electric motor as claimed in claim 2, wherein the encoder element is arranged, in a direction parallel to an axis of the electric motor, in a region of the end shield.

4. The electric motor as claimed in claim 3, wherein the encoder element is arranged between a bearing of the motor supported by the end shield and a shielding element.

5. The electric motor as claimed in claim 1, wherein the shielding element magnetically shields the sensor against a magnetic field acting externally on the electric motor.

6. The electric motor as claimed in claim 1, wherein the end shield has a seating surface for supporting the shielding element in a direction parallel to the electric motor.

7. The electric motor as claimed in claim 6, wherein the seating surface is for taking a mechanical force applied to the shielding element.

8. The electric motor as claimed in claim 1, wherein the end shield has a recess for receiving the sensor and/or a recess for receiving a cable connected to the sensor.

9. The electric motor as claimed in claim 8, wherein the recess for receiving the sensor and/or the recess for receiving a cable connected to the sensor is set back from a seating surface in a direction parallel to an axis of the electric motor, and/or forms a depression in the seating surface.

10. The electric motor as claimed in claim 1, wherein the end shield is a cast part.

11. The electric motor as claimed in claim 10, wherein a recess for receiving a cable, a recess for receiving the sensor and/or a receiver for a strain relief element for the cable are formed into the end shield by casting.

12. The electric motor as claimed in claim 1, wherein the shielding element includes a shielding plate.

13. The electric drive unit as claimed in claim 1, wherein the brake is electromagnetically actuated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further practical embodiments and advantages of the system described herein are described below in conjunction with the drawings. There are shown:

(2) FIG. 1 is a perspective representation of a part of an electric drive unit according to the system described herein;

(3) FIG. 2 is a perspective sectional representation of the part of the drive unit;

(4) FIG. 3 is a cross-sectional representation of the part of the electric drive unit; and

(5) FIG. 4 is an enlarged partial representation of a region from FIG. 3.

DESCRIPTION OF VARIOUS EMBODIMENTS

(6) In some embodiments, the electric drive unit 1 has an electric motor having a brake 3 arranged on the shaft 2 of the electric motor. Of the electric motor, only the rotor 4 and the end shield 5 facing the brake 3 are represented in the figures. In the example shown, the end shield 5 is the end shield opposite the output side of the electric motor, and also may be referred to as the B-end shield.

(7) The brake 3 may be a spring-loaded brake that can be actuated electromagnetically. The brake 3 may have a manual lifter device 6. The sensor 7 may be integrated into the end shield 5. In the example shown, this integration may be made possible by a receiving space, in the form a recess for the sensor 7, that is molded into the end shield 5. The receiving space, or recess, may be closed—as shown as an example—by a shielding element 8.

(8) As in the example shown, a recess 14 may be provided to receive a cable for connection to sensor 7 in the end shield 5. As in the example shown, it may be at least partially closed by the shielding element 8. The recess may have moldings and/or connection elements for fixing a strain relief element for the cable.

(9) The encoder element 9 may be arranged on shaft 2 as in the example shown and, in particular, may be connected to shaft 2 in a rotationally fixed manner. In this context, a rotationally fixed connection is to be understood to mean, in particular, that the encoder element does not move on the shaft 2, in the circumferential direction of the shaft 2, when the electric motor, or the electric drive unit, is used as intended.

(10) In a direction parallel to the axis X, or to the shaft 2, of the electric motor, the sensor 7 and the encoder element 9 may be arranged, as in the example shown, between the bearing 10 supported by the end shield 5 and the shielding element 8.

(11) In the example shown, the encoder element 9 is supported on a shaft shoulder 11 in a direction parallel to the axis X of the electric motor. However, the support also may be effected in other ways, for example—if necessary with use of an intermediate element—on the bearing 10.

(12) In the example shown, the shielding element 8 engages in the encoder element 9 in the manner of a labyrinth seal. For this purpose, the shielding element 8 may have a region 12 extending along the shaft 2. Alternatively and/or in addition, it is possible to attach a sealing element such as, for example, a rotary shaft seal, to the shielding element 8. This may be effected, for example, in the region of the surface 13 of the shielding element 8 that faces toward the shaft 2.

(13) The end shield 5 may have a seating surface 15 for seating, or supporting, the shielding element 8 in the direction of the axis X of the electric motor. The recess for receiving the sensor 7 and the recess 14 for receiving the cable may be designed in such a manner that they are set back from the seating surface 15 as represented. Due to the flat bearing contact of the shielding element 8 and the seating surface 15, the shielding element 8 may take up comparatively large forces, which, at least substantially, are directed parallel to the axis X of the electric motor. The forces may be introduced via the shielding element 8 into the seating surface 15, which supports the shielding element 8 in a direction parallel to the axis X of the electric motor.

(14) In the example represented, the brake may have a magnet housing 16, a brake rotor 17 and a friction plate 18. The brake rotor 17 may be connected to the shaft 2 in a rotationally fixed and axially displaceable manner. When the brake 3 is closed, or engaged, the brake rotor 17 is pressed against the friction plate 18. The forces thus introduced into the friction plate 18 along the axis X of the motor may be taken up by the shielding element 8 and introduced by it, via the seating surface 15, into the end shield 5. Alternatively, it is also possible for a surface of the shielding element 8 facing the brake to form a friction surface of the brake. Then, in particular, the friction plate 18 may be omitted. In this case, it is possible that, during closing, or engaging, of the brake, the brake rotor 17 is pressed directly onto this surface of the shielding elements 8. For this purpose, the surface of the shielding element 8 may have a suitable coating, especially a friction lining.

(15) The features of the system described herein as disclosed in the present description, in the drawings and in the claims may be essential for the realization of the invention in its various embodiments, both individually or in any combination. The invention is not limited to the embodiments described. It may be varied within the scope of the claims, and in consideration of the knowledge of persons skilled in the art. Other embodiments of the system described herein will be apparent to those skilled in the art from a consideration of the specification and/or an attempt to put into practice the system described herein. It is intended that the specification and examples be considered as illustrative only, with the true scope and spirit of the invention being indicated by the following claims.