ELECTRIC POWER TOOL AND METHOD FOR OPERATING SAME

• US 20070247097A1
• Filed: 04/03/2007
• Published: 10/25/2007
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Lamprecht, Dirk, Seiler, Hartmut
• Granted Patent: US 7,795,829 B2
• Time in Patent Office: Days
• US Class Current: 318/432
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers
• CPC Class Codes: B25F 5/001 Gearings, speed selectors, clutches or the like specially adapted for rotary tools
• CPC Class Codes: Y10S 388/937 Hand tool

Abstract

In an electric power tool and a method for operating an electric power tool, a torque limitation of an electric motor reacts when a load moment exceeds a predetermined threshold and in which an output request is carried out by means of a switch. A supply of current to the motor is interrupted when a criterion for the reaction of the torque limitation is detected based on a speed detection of the motor.

Claims

1. A method for operating an electric power tool, comprising the steps of reacting by a torque limitation of an electric motor when a load moment exceeds a predetermined threshold;

carrying out an output request by a switch;

interrupting a supply of current to the electric motor in at least partially automatic fashion when a criterion for a reaction of the torque limitation is detected.

2. A method as defined in claim 1;

and further comprising interrupting a connection between the electric motor and a battery unit that powers the electric motor, a criterion for a reaction of the torque limitation is detected.

3. A method as defined in claim 1;

and further comprising interrupting a connection between the electric motor and a battery unit that powers the electric motor in at least one partially automated fashion when a criterion for a reaction of the torque limitation is detected.

4. A method as defined in claim 1;

and further comprising deriving the criterion from a speed detection of the electric motor.

5. A method as defined in claim 1;

and further comprising using as the criterion a criterion selected from the group consisting of a rapid drop in a speed of the electric motor, a stoppage of the electric motor, and both.

6. A method a defined in claim 1;

and further comprising after a reaction of the torque limitation, supplying the electric motor with current again when the output request is reduced and then increased again.

7. A method as defined in claim 1;

and further comprising after a reaction of the torque limitation, supplying the electric motor with current again When a predetermined time span has elapsed.

8. A method as defined in claim 7;

and further comprising selecting the time span by a user.

9. A method as defined in claim 7;

and further comprising during the time span, maintaining the output request or increasing the output request.

10. A method as defined in claim 1;

and further comprising after a resumption of the supply of current, increasing a limit value of the torque limitation.

11. A method as defined in claim 10;

and further comprising limiting a speed of the electric motor.

12. An electric power tool, comprising an electric motor in which a torque limitation is provided when a load moment exceeds a predetermined threshold;

a switch by which an output request of said electric motor is carried out; and

means for interrupting a supply of current to said electric motor when a criterion for a reaction of the torque limitation is detectable.

13. An electric power tool as defined in claim 12;

and further comprising means for interrupting a supply of current to said electric motor when a criterion for a reaction of the torque limitation is detected based on a speed detection of said electric motor.

14. An electric power tool as defined in claim 12;

and further comprising means for detecting a rapid drop in a parameter selected from the group consisting of a speed of said electric motor, a stoppage of said electric motor, and both.

15. An electric power tool as defined in claim 12;

and further comprising means for speed limitation upon resumption of a supply of current to said electric motor.

16. An electric power tool, comprising an electric motor in which a torque limitation is provided when a load moment exceeds a predetermined threshold;

a switch by which an output request is carried out; and

means for interrupting in an least partially automated fashion a connection between said electric motor and a battery unit that powers said electric motor when a criterion for a reaction of the torque limitation is detectable.

17. An electric power tool as defined in claim 16;

and further comprising means for interrupting a supply of current to said electric motor when a criterion for a reaction of the torque limitation is detected based on a speed detection of said electric motor.

18. An electric power tool as defined in claim 16;

and further comprising means for detecting a rapid drop in a parameter selected from the group consisting of a speed of said electric motor, a stoppage of said electric motor, and both.

19. An electric power tool as defined in claim 16;

and further comprising means for speed limitation upon resumption of a supply of current to said electric motor.