Power Tool and Battery Pack

• US 20120274245A1
• Filed: 01/21/2011
• Published: 11/01/2012
• Est. Priority Date: 01/22/2010
• Status: Abandoned Application

• Current Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Takano, Nobuhiro, Funabashi, Kazuhiko, Shima, Yukihiro, Nakayama, Eiji
• Application Number:
  US13/496,810
• Publication Number:
  US 20120274245A1
• Time in Patent Office: Days
• US Class Current: 318/139
• 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: B25F 5/021 with guiding devices guiding devices for hand tools on stands or supports B25H1/0078
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A power tool is connectable to a battery pack including a secondary battery. The power tool includes a motor and a prohibiting unit. The motor is driven with an electrical power supplied from the secondary battery. The prohibiting unit prohibits the supply of the electrical power to the motor based on a drop amount of a voltage of the secondary battery.

Claims

1. A power tool connectable to a battery pack including a secondary battery, comprising:

a motor driven with an electrical power supplied from the secondary battery; and

a prohibiting unit that prohibits the supply of the electrical power to the motor based on a drop amount of a voltage of the secondary battery.

2. The power tool according to claim 1, wherein the prohibiting unit prohibits the supply of the electrical power to the motor when the drop amount exceeds a first threshold.

3. The power tool according to claim 1, wherein the first threshold depends on at least one of a temperature of the secondary battery and a capacity of the secondary battery.

4. The power tool according to claim 1, further comprising a trigger switch that is manually closed to supply the electrical power to the motor,

wherein once prohibiting the supply of the electrical power to the motor, the prohibiting unit continues to prohibit the supply of the electrical power to the motor until the trigger switch is opened.

5. The power tool according to claim 1, further comprising a trigger switch that is manually closed to supply the electrical power to the motor,

wherein the prohibiting unit detects the drop amount every predetermined period since the trigger switch has been closed, the predetermined period being set to a value such that the prohibiting unit fails to detect the drop amount occurring due to a starting current.

6. The power tool according to claim 1, wherein the prohibiting unit prohibits the supply of the electrical power to the motor by shutting off a switching unit disposed on a current path between the secondary battery and the motor.

7. The power tool according to claim 1, wherein the secondary battery is a lithium-ion secondary battery.

8. The power tool according to claim 2, wherein the prohibiting unit prohibits the supply of the electrical power to the motor, at least one of when the drop amount exceeds the first threshold and when a capacity of the secondary battery falls below a second threshold for an overdischarge.

9. A battery pack connectable to a power tool including a motor, comprising:

a secondary battery that supplies an electrical power to the motor to drive the motor; and

a prohibiting unit that prohibits the supply of the electrical power to the motor based on a drop amount of a voltage of the secondary battery.

10. The battery pack according to claim 9, wherein the prohibiting unit prohibits the supply of the electrical power to the motor when the drop amount exceeds a first threshold.

11. The battery pack according to claim 9, wherein the first threshold depends on at least one of a temperature of the secondary battery and a capacity of the secondary battery.

12. The battery pack according to claim 9, further comprising a trigger switch that is manually closed to supply the electrical power to the motor,

wherein once prohibiting the supply of the electrical power to the motor, the prohibiting unit continues to prohibit the supply of the electrical power to the motor until the trigger switch is opened.

13. The battery pack according to claim 9, further comprising a trigger switch that is manually closed to supply the electrical power to the motor,

wherein the prohibiting unit detects the drop amount every predetermined period since the trigger switch has been closed, the predetermined period being set to a value such that the prohibiting unit fails to detect the drop amount occurring due to a starting current.

14. The battery pack according to claim 9, wherein the prohibiting unit prohibits the supply of the electrical power to the motor by shutting off a switching unit disposed on a current path between the secondary battery and the motor.

15. The battery pack according to claim 9, wherein the secondary battery is a lithium-ion secondary battery.

16. The battery pack according to claim 10, wherein the prohibiting unit prohibits the supply of the electrical power to the motor, at least one of when the drop amount exceeds the first threshold and when a capacity of the secondary battery falls below a second threshold for an overdischarge.