Patent ID: 8344675

Claim:
A rechargeable electric power tool comprising a motor driven by a secondary battery as a power source, a switching element for regulating power distribution to the motor, a motor control unit for controlling rotation of the motor through the switching element, a lead wire for supplying a drive current to the motor therethrough and a trigger switch changed over by a user for turning on or off the drive current supplied to the motor through the lead wire, wherein, upon changeover of the trigger switch, the motor control unit determines the magnitude relation between a detected temperature T 1 corresponding to a temperature detection signal outputted from a first temperature detector unit arranged on the lead wire and a preselected first temperature threshold value T th1 , wherein, if the detected temperature T 1 is determined to be greater than the first temperature threshold value T th1 , the motor control unit is set in a limited operation mode in which the motor control unit stops rotation of the motor or in which the revolution number of the motor is limited to a predetermined value or less, and, wherein, in the limited operation mode and upon changeover of the trigger switch, the motor control unit determines the magnitude relation between the detected temperature T 1 and a second temperature threshold value T th2 lower than the first temperature threshold value T th1 by a preset temperature difference ΔT 1 and wherein, if the detected temperature T 1 is determined to be equal to or smaller than the second temperature threshold value T th2 , the motor control unit releases the limited operation mode.