Electric parking brake device

An electric parking brake device comprising an electric motor, a pressing member, and brake pads, wherein a rotational speed of a rotation shaft of the electric motor installed in a motor housing is decelerated and a rotational movement of the rotation shaft is converted to a linear movement so as to be transmitted to the pressing member, wherein a brake disk rotating with a wheel is pressed with the brake pads biased by the pressing member so that a braking force is affected to the wheel, and wherein the electric motor is controlled by a controller;

• the electric parking brake device further comprising a resolver which has
• a rotating plate which is fixed to the rotation shaft of the electric motor,
• a base arranged in a resolver housing so as to face the rotating plate,
• a first sheet coil comprising a detecting coil and arranged on an opposite face of the rotating plate so as to face the base,
• a second sheet coil comprising a primary coil of an output transformer and arranged on the opposite face of the rotating plate so as to face the base, the primary coil being coupled to the detecting coil,
• a third sheet coil comprising an excitation coil opposite to the detecting coil and arranged on the opposite face of the base so as to face the rotating plate, and
• a fourth sheet coil comprising a secondary coil of the output transformer opposite to the primary coil of the output transformer and arranged on the opposite face of the base so as to face the rotating plate, wherein the controller has
• a resolver control circuit comprising an input circuit for inputting an excitation signal to the excitation coil of the resolver and an output circuit for processing an output signal occurring from the secondary coil of the output transformer, and
• a motor control circuit for controlling the electric motor based on an output from the output circuit of the resolver control circuitry,
• wherein a load sensor is arranged so as to be in pressure contact with an end of the rotation shaft in order to detect a thrust load of the rotation shaft,
• wherein a torque control circuit for calculating a clamping force to the brake disk by the brake pads based on a torque detection signal given from the load sensor is installed in the controller, and
• wherein the electric motor is controlled by the motor control circuit based on output from respective of the torque control circuit and the output circuit of the resolver control circuit.