Patent ID: 7068000

Claim:
A torque control device for an electrical tool having a motor powered by a DC voltage source, the torque control device comprising: a switching circuit being connected between the motor and the DC voltage source; a processor with an output terminal being connected to the switching circuit to turn on or turn off the switching circuit; a voltage detecting circuit having an input terminal being connected between the motor and the DC voltage source to detect voltage variation data of the motor; a torque detecting circuit being connected between the voltage detecting circuit and the processor to produce a motor torque value to be output to the processor based on the voltage variation data; a torque setting unit being connected to the processor to provide a default torque value to the processor; a high voltage protecting circuit being connected between the voltage detecting circuit and the processor and comprising an operating amplifier having two input terminals being connected respectively to the voltage detecting circuit and a high reference voltage; and an output terminal being connected to the processor; a low voltage protecting circuit being connected between the voltage detecting circuit and the processor and comprising an operating amplifier having two input terminals being connected respectively to the voltage detecting circuit and a low reference voltage; and an output terminal being connected to the processor; and a display being connected to the processor to show the default torque.