ELECTRIC TOOL HAVING COLD START FUNCTION

• US 20100186975A1
• Filed: 04/23/2008
• Published: 07/29/2010
• Est. Priority Date: 06/18/2007
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Glauning, Rainer
• Application Number:
  US12/665,605
• Publication Number:
  US 20100186975A1
• Time in Patent Office: Days
• US Class Current: 173/1
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H02P 1/02 Details
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The effectiveness with which an electric tool having a rechargeable battery can be operated is dependant on the temperature prevailing in the electric tool. In order to increase the operation of the electric tool at low temperatures, a cold start function that can be activated is provided in the electric tool.

Claims

1-19. -19. (canceled)

20. An electric tool, comprising

a tool switch;

a rechargeable battery; and

an activatable cold start mechanism.

21. The electric tool as defined by claim 20, further comprising a temperature sensor which detects the temperature of the rechargeable battery.

22. The electric tool as defined by claim 20, further comprising an optical display device, in particular an LED, is provided for displaying an activation of the cold start mechanism.

23. The electric tool as defined by claim 21, further comprising an optical display device, in particular an LED, is provided for displaying an activation of the cold start mechanism.

24. The electric tool as defined by claim 20, wherein the activatable cold start mechanism is embodied as a short-circuit current path having a resistor.

25. The electric tool as defined by claim 24, wherein the short-circuit current path is guided in a vicinity of the rechargeable battery in such a way that the resistor is usable for warming up the rechargeable battery.

26. The electric tool as defined by claim 20, wherein the cold start mechanism is embodied as a warmup current path via the motor.

27. The electric tool as defined by claim 26, further comprising a device for mechanically decoupling the motor from powering the tool during a time of activation of the cold start mechanism.

28. The electric tool as defined by claim 27, wherein the device for mechanically decoupling the motor is embodied as a clutch.

29. The electric tool as defined by claim 26, further comprising a device for blocking the motor during a time of activation of the cold start mechanism.

30. The electric tool as defined by claim 29, wherein the device for blocking the motor is embodied as a mechanical fixation or as an electric high-frequency repolarization of the motor.

31. The electric tool as defined by claim 30, wherein for the device for blocking is a bolt.

32. A method for cold starting an electric tool having a tool switch and a rechargeable battery, comprising the steps of:

detecting a temperature in the electric tool;

comparing the temperature detected in the electric tool with a threshold temperature; and

activating a cold start function if the temperature detected is below the threshold temperature.

33. The method as defined by claim 32, further comprising the step of displaying the activation of the cold start function by an acoustical or optical display device, in particular an LED.

34. The method as defined by claim 32, wherein during the cold start function, a short-circuit current path with a heating resistor is activated.

35. The method as defined by claim 32, wherein during the cold start function, current is guided via the motor of the electric tool, and the motor blocked and/or decoupled from powering the tool.

36. The method as defined by claim 35, wherein the motor is blocked by repolarizing the motor at a constant or variable frequency in clockwise/counterclockwise rotation.

37. The method as defined by claim 36, wherein the repolarizing of the motor is effected at a frequency high enough that the motor does not start.

38. The method as defined by claim 36, wherein the temperature is detected at the rechargeable battery, and the frequency is varied as a function of a instantly measured temperature and/or of a current instantly furnishable by the rechargeable battery.

39. The method as defined by claim 38, wherein a short-circuit current is varied as a function of the instantly measured temperature.