Power tool

Abstract

A power tool 1 is connected to a battery pack 5 including an overcurrent detector 533 which detects overcurrent of a battery module 51 and outputs a detection signal, and an overdischarge detector 532 which detects overdischarge of the battery module 51 and outputs a detection signal. The power tool 1 includes a motor 2 which is driven by electric power supplied from the battery pack 5 , a trigger switch 31 for setting the power supply from the battery pack 5 to the motor 2 in ON/OFF state, and an FET 410 which sets the power supply to the motor 2 in ON/OFF state on the basis of the detection signal from the overcurrent detector 533 or the overdischarge detector 532.

1 . A power tool connected to a battery pack including a battery and a battery state monitoring means which detects overcurrent or overdischarge of the battery and outputs a detection signals comprising:
 a drive part driven by electric power supplied from the battery;   a first switch unit setting arbitrarily power supply from the battery to the drive part in ON/OFF state; and   a second switch unit setting the power supply to the drive part in ON/OFF state on the basis of the detection signal.   
   
   
       2 . The power tool according to  claim 1 , further comprising:
 retaining means which retains, in case that the first switch unit is in ON state and the power supply to the drive part is interrupted by the second switch unit, the interruption state of power supply to the drive part by the second switch unit while the first switch unit is in the ON state.   
   
   
       3 . The power tool according to  claim 1 , comprising:
 first signal output means which outputs a first signal for turning on the second switch unit; and   second signal output means which outputs a second signal for turning off the second switch unit, wherein in case that the battery and the drive part are connected in a state where the first switch unit is turned on, the second signal is input into the second switch unit.   
   
   
       4 . The power tool according to  claim 3 , wherein:
 the first signal output means includes a resistor and a condenser, and the second signal output means includes at least a resistor and a condenser; and   time constant by the resistor and the condenser is larger in the second signal output means than that in the first signal output means.   
   
   
       5 . The power tool according to any one of  claims 1  to  4 , further comprising:
 informative means which informs a state of the second switch unit of a user.   
   
   
       6 . A power tool connected to a battery pack including a battery, comprising:
 a drive part driven by electric power supplied from the battery;   a first switch unit for setting arbitrarily power supply from the battery to the drive part in ON/OFF state;   a second switch unit for setting the power supply to the drive part in ON/OFF state on the basis of a detection signal according to a state of the battery pack;   first signal output means which outputs a first detection signal for permitting the power supply from the battery to the drive part to the second switch unit; and   second signal output means which outputs a second detection signal for interrupting the power supply from the battery to the drive part to the second switch unit,   wherein in case that the battery and the drive part are connected in a state where the first switch unit is turned on, the second detection signal is input into the second switch unit.