Brake device for an electric motor

• US 7,108,110 B2
• Filed: 12/11/2003
• Issued: 09/19/2006
• Est. Priority Date: 04/01/2003
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Habele, Michael
• Primary Examiner(s): Schwartz, Christopher P.
• Application Number:
  US10/507,997
• Publication Number:
  US 20050199453A1
• Time in Patent Office: 1,013 Days
• Field of Search: 310 77-105, 188156-164
• US Class Current: 188/156
• CPC Class Codes: F16D 2121/22 for releasing a normally applied brake
• CPC Class Codes: F16D 49/00 Brakes with a braking member co-operating with the periphery of a drum, wheel-rim, or the like similar clutches F16D13/10
• CPC Class Codes: F16D 65/14 Actuating mechanisms for brakes; Means for initiating operation at a predetermined position brake control systems, parts thereof B60T
• CPC Class Codes: H02K 7/1026 using stray fields

Abstract

The invention is based on a braking device for an electric motor with a stator (14, 16, 18) and a rotor (10), in particular for a direct current series-wound motor, with a braking element (20) that can be moved between an operating position and a braking position depending on a magnetic flux in the stator (14, 16, 18), wherein there is an air gap (32) between the braking element (20) and the stator (14, 16, 18), and with a short-circuit ring (38) for suppressing mechanical vibrations. The invention proposes that the short-circuit ring (38) be inclined in relation to the air gap (32) between the stator (14, 16, 18) and the braking element (20).

Claims

1. A braking device for an electric motor with a stator (14, 16, 18) and a rotor (10) composing:

a braking element (20) that can be moved between an operating position and a braking position depending on a magnetic flux in the stator (14, 16, 18), wherein there is an air gap (32) between the braking element (20) and the stator (14, 16, 18), and with a short-circuit ring (38) for suppressing mechanical vibrations, wherein a surface enclosed by the short-circuit ring (38) is inclined in relation to a boundary surface (42) of the braking element (20) in relation to the air gap (32) between the stator (14, 16, 18) and the braking element (20), wherein the magnetic flux traveling through the braking element (20) is comprised of a main magnetic flux (I_H) flowing through the short-circuit ring (38) and a secondary magnetic flux (I_N) that bypasses the short-circuit ring (38), and wherein the air gap (32) between the braking element (20) and the stator (14, 16, 18) is smaller in the region of the main magnetic flux (I_H) than in the region of the secondary magnetic flux (I_N).

2. The braking device according to claim 1, wherein the surface enclosed by the short-circuit ring (38) is oriented essentially at right angles to the boundary surface (42) of the braking element (20) in relation to the air gap (32) in the operating position of the braking element (20).

3. The braking device according to claim 1, wherein the boundary surface (42) is recessed in the region of the secondary magnetic flux (I_N) in relation to the region of the main magnetic flux (I_H) in order to increase the size of the air gap (32).

4. The braking device according to claim 1, wherein the stator (14, 16, 18) has a yoke (14, 16) and a stator winding (18), wherein between the stator winding (18) and the air gap (32) in relation to the braking element (20), the yoke (14, 16) has a bottleneck (40) that represents a magnetic resistance in the yoke (14) so that the main magnetic flux (I_H) bypasses the bottleneck (40) while the secondary magnetic flux (I_N) passes through the bottleneck (40) until it reaches saturation.

5. The braking device according to claim 4, wherein the short-circuit ring (38) is situated in the region of the bottleneck (40) of the yoke (14).

6. The braking device according to claim 1, wherein the braking element (20) is embodied as a pivoting lever with a braking arm (24) and a releasing arm (26).

7. The braking device according to claim 6, wherein the short-circuit ring (38) encompasses the entire releasing arm (26) of the braking element (20).

8. The braking device according to claim 1, wherein the short-circuit ring (38) is at least partially caulked or welded to the braking element (20).

9. The braking device according to claim 8, wherein the short-circuit ring (38) is welded to the braking element (20) on the side oriented away from the air gap (32).

10. An electric motor with a braking device according to claim 1.

11. A machine tool with an electric motor according to claim 10.

12. The braking device according to claim 1, wherein the electric motor is a direct current series-wound motor.