An output shaft of a wiper motor is connected to a wiper to transmit a rotational force of the wiper motor to the wiper to reciprocally swing the wiper between an upper return position and a lower return position in response to forward and backward rotations of the output shaft upon energization of the wiper motor. When the wiper is stopped at the lower return position, the control unit executes a stop position holding control operation in such a manner that the control unit controls a rotational direction of the wiper motor to apply a rotational force to the wiper in a downward direction and controls the rotational force of the wiper motor based on a speed of the vehicle to substantially maintain the wiper at the lower return position.
1. A wiper system for a vehicle, comprising:
a wiper that is supported by a body of the vehicle in a swingable manner to wipe a front glass of the vehicle;
a wiper motor that has an output shaft, which is connected to the wiper to transmit a rotational force of the wiper motor to the wiper to reciprocally swing the wiper between an upper return position and a lower return position in response to forward and backward rotations of the output shaft upon energization of the wiper motor; and
a control unit that controls the wiper motor, wherein when the wiper is stopped at the lower return position, the control unit executes a stop position holding control operation in such a manner that the control unit controls a rotational direction of the wiper motor to apply a rotational force to the wiper in a downward direction and controls the rotational force of the wiper motor based on a speed of the vehicle to substantially maintain the wiper at the lower return position.
2. The wiper system according to claim 1 , wherein when the wiper is stopped at the lower return position in an intermittent mode, in which the wiper is intermittently driven to swing the wiper between the upper return position and the lower return position, the control unit executes the stop position holding control operation.
3. The wiper system according to claim 1 , wherein:
the wiper motor is operable to displace the wiper to a park position, which is located on a lower side of the lower return position in response to rotation of the output shaft; and
when the wiper is stopped at the lower return position in a park mode, in which the wiper is moved to the park position after temporarily stopping the wiper at the lower return position, the control unit executes the stop position holding control operation.
4. The wiper system according to claim 1 , further comprising:
a crank arm that has one end portion, which is fixed to the output shaft;
a link rod that has one end portion, which is rotatably connected to the other end portion of the crank arm;
a pivot lever that has one end portion, which is rotatably connected to the other end portion of the link rod; and
a pivot shaft that is rotatably supported by the body of the vehicle and is fixed to the other end portion of the pivot lever, wherein the wiper is fixed to the pivot shaft, and the crank arm and the link rod are aligned to extend generally along an imaginary straight line when the wiper is placed in the park position.