Power Tool With Dynamic and Mechanical Brake

• US 20070287365A1
• Filed: 05/02/2007
• Published: 12/13/2007
• Est. Priority Date: 04/13/2004
• Status: Abandoned Application

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Wikle, David, Rice, Gregory, Melvin, Jason, Gorti, Bhanuprasad, Deshpande, Uday, Hilsher, William, Waikar, Shailesh
• Application Number:
  US11/743,170
• Publication Number:
  US 20070287365A1
• Time in Patent Office: Days
• US Class Current: 451/357
• CPC Class Codes: B24B 23/03 the tool being driven in a combined movement

Abstract

A power tool in accordance with an embodiment of the invention has a motor driving a member, a switch coupled across windings of the motor that dynamically brakes the motor, and a mechanical brake that brakes speed of the member. In an aspect, the combined dynamic and mechanical braking brakes speed of the member to a desired speed in no more than about two second. In an aspect, the motor is an electronically commutated motor and the power tool includes a controller that electronically commutates the motor by switching switches that switch power to the motor in an electronic commutation sequence and switches the switches to electronically brake the motor.

Claims

1. A power tool, comprising:

a motor driving a member;

a switch coupled across windings of the motor that dynamically brakes the motor;

and a mechanical brake that brakes speed of the member.

2. The apparatus of claim 1 wherein the combined dynamic and mechanical braking brakes speed of the member to a desired speed in no more than about two seconds.

3. The apparatus of claim 2 wherein the desired speed is stop.

4. The apparatus of claim 2 wherein the desired speed is an idle speed.

5. The apparatus of claim 1 including a resistor that is coupled across windings of the motor by the switch in dynamically braking the motor.

6. The apparatus of claim 1 wherein the switch shorts the motor windings to dynamically brake the motor.

7. A power tool, comprising:

an electronically commutated motor driving a member;

a motor controller that electronically commutates the motor by switching switches that switch power to the motor in an electronic commutation sequence and switches the switches to electronically brake the motor; and

a mechanical brake that brakes speed of the member.

8. The apparatus of claim 7 wherein the controller switches the switches to short a winding of the motor to electronically brake the motor.

9. The apparatus of claim 7 wherein the combined electronic and mechanical braking brakes speed of the member to a desired speed in no more than about two seconds.

10. The apparatus of claim 9 wherein the desired speed is stop.

11. The apparatus of claim 9 wherein the desired speed is an idle speed.

12. The apparatus of claim 7 including a resistor that is coupled across windings of the motor when the motor controller electronically brakes the motor.

13. The apparatus of claim 7 including an on/off switch and the motor controller sensing collapse of an input voltage when the on/off switch is turned off and switching the switches to electronically brake the motor.

14. The apparatus of claim 13 wherein the mechanical brake mechanically braking the member and the motor controller electronically braking the motor brakes speed of the member to a desired speed in no greater than about two seconds.

15. The apparatus of claim 14 wherein the desired speed is stop.

16. The apparatus of claim 14 wherein the desired speed is an idle speed.

17. The apparatus of claim 13 including a resistor that is coupled across windings of the motor when the motor controller electronically brakes the motor.

18. The apparatus of claim 7 wherein the motor controller switches the switches to reverse commutate the motor to electronically brake the motor.