Patent ID: 8626412
Filing Date: 2014-01-07
Classification: B60W,F16H

Abstract:
1. A shift-by-wire system for changing a mode position of the automatic transmission of a vehicle according to a signal of a shift selector manipulated by a driver of the vehicle, the shift-by-wire system comprising: an actuator including an electric motor, an incremental type encoder outputting a pulse signal according to a rotation of the motor, and a reduction gear reducing the rotation of the motor and outputting the reduced rotation; a detent plate connected to the reduction gear to be rotated by the actuator, the detent plate having a first end concave portion formed at one end in a rotational direction thereof, a second end concave portion formed at the other end in a rotational direction, and a plurality of middle concave portions formed between the first end concave portion and the second end concave portion; a detent spring having a regulating portion which can be engaged with one of the first end concave portion, the middle concave portions, and the second end concave portion to regulate a rotation of the detent plate so that the mode position of the automatic transmission is fixed; and a control portion defining a target mode position based on the signal of the shift selector and driving the actuator so that the mode position of the automatic transmission is brought into the target mode position, wherein the first end concave portion corresponds to a parking-mode position and defines a first wall, the second end concave portion corresponds to a position for driving a vehicle forward and defines a second wall, the middle concave portions correspond to at least a reverse-mode position and a neutral-mode position, the control portion includes: wherein when a vehicle electric power source is turned on, the first position learning portion learns the first reference position in a case that the target mode position is the parking-mode position, the second position learning portion learns the second reference position in a case that the target mode position is a mode position corresponding to the second end concave portion, the control portion does not drive the actuator to maintain a current mode position in a case that the target mode position is other than the parking-mode position and a mode position corresponding to the second end concave portion, the control portion accepts only a requirement for changing the mode position to the parking-mode position or the mode position corresponding to the second end concave portion, the first position learning portion learns the first reference position when it is required to change the mode position to the parking-mode position, and the second position learning portion learns the second reference position when it is required to change the mode position to the mode position corresponding to the second end concave portion.