Stall protection for brush motors with rotation sensing brush device

• US 6,791,218 B1
• Filed: 05/13/2003
• Issued: 09/14/2004
• Est. Priority Date: 03/20/2003
• Status: Expired due to Fees

• Current Assignee: Siemens VDO Automotive, Inc. (Continental AG)
• Original Assignee: Siemens VDO Automotive, Inc. (Continental AG)
• Inventors: Radakovic, Dragan, Simofi-Ilyes, Attila, Lakerdas, Andrew, Dragoi, Corneliu
• Primary Examiner(s): Lam, Thanh
• Application Number:
  US10/437,104
• Time in Patent Office: 490 Days
• Field of Search: 310/68.B, 310/179, 310/233, 310/248, 310/67.R, 310/68.R, 318/138, 318/254, 318/560, 318/563, 318/434, 318/601, 318/439
• US Class Current: 310/68.00B
• CPC Class Codes: H02K 23/66 Structural association with auxiliary electric devices influencing the characteristic of, or controlling, the machine, e.g. with impedances or switches

Abstract

A system and method for protecting a motor from a stall condition includes a brush motor 11 having power brushes 14 and 16 that convey power to windings of the motor, and one sensing brush 20 constructed and arranged to sense a speed of rotation of an armature motor. A controller 23 is constructed and arranged to compare a sensed speed of rotation with a minimum speed value that is indicative of a stall condition. A relay 28 is constructed and arranged to disconnect power to the motor if the sensed speed is below the minimum speed value.

Claims

1. A method of protecting a brush motor from a stall condition, the method including the steps of:

providing a brush motor having power brushes that convey power to windings of the motor, and one sensing brush constructed and arranged to obtain an AC signal indicative of a speed of rotation of an armature of the motor, with the speed of rotation being proportional to a frequency of the AC signal,

powering the motor,

obtaining the AC signal with the sensing brush and determining the speed of rotation of the armature,

comparing the determined speed of rotation of the armature with a minimum speed value that is indicative of a stall condition of the motor, and

disconnecting power to the motor if the determined speed of rotation of the armature is below the minimum speed value.

2. The method of claim 1, wherein the step of disconnecting power to the motor includes activating a relay.

3. The method of claim 1, wherein the minimum speed value indicates at least a partial stall condition of the motor.

4. The method of claim 1, further including, after powering the motor, establishing a time delay period sufficient to permit the motor to generate speed, prior to executing the comparing step.

5. The method of claim 1, further including generating an alarm signal to indicate that a stall condition is present while the power remains disconnected from the motor.

6. The method of claim 5, further including receiving the alarm signal at an engine control unit, and resetting the relay, via the engine control unit, once the stall condition is no longer present.

7. A system for protecting a motor from a stall condition comprising:

a brush motor having power brushes that convey power to windings of the motor, and one sensing brush constructed and arranged to obtain an AC signal indicative of a speed of rotation of an armature of the motor, with the speed of rotation being proportional to a frequency of the AC signal,

means for comparing a speed of rotation obtained by the sensing brush with a minimum speed value that is indicative of a stall condition of the motor, and

means for disconnecting power to the motor if the speed of rotation obtained by the sensing brush is below the minimum speed value.

8. The system of claim 7, wherein the means for disconnecting power to the motor is a relay.

9. A system for protecting a motor from a stall condition comprising:

a brush motor having power brushes that convey power to windings of the motor, and one sensing brush constructed and arranged to obtain an AC signal indicative of a speed of rotation of an armature of the motor, with the speed of rotation being proportional to a frequency of the AC signal,

comparing structure constructed and arranged to compare a speed of rotation obtained by the sensing brush with a minimum speed value that is indicative of a stall condition of the motor, and

a relay constructed and arranged to disconnect power to the motor if the speed of rotation obtained by the sensing brush is below the minimum speed value.

10. The system of claim 9, wherein the comparing structure and relay are integrated into a lead wire assembly that includes positive and negative power leads.

11. The system of claim 10, further including a connector assembly having a first connector constructed and arranged to connect with the lead wire assembly and a second connector constructed and arranged to connect with a vehicle connector.

12. The system of claim 11, wherein the connector assembly includes a resistor constructed and arranged to be employed for low speed operation of the motor.

13. The system of claim 9, further including alarm generating structure constructed and arranged to generate an alarm signal wherein a stall condition occurs.

14. The system of claim 13, further including an engine control unit constructed and arranged to receive the alarm signal and to reset the relay.

15. The system of claim 9, wherein the sensing brush is of dimensions smaller than the dimensions of each power brush.

16. The system of claim 9, wherein the comparing structure includes a transistor.