Shift device

1. A shift device configured to be mounted on a vehicle, the shift device comprising:

a shift switching member that includes a plurality of valley parts corresponding to a shift position;

a positioning member that is provided to establish the shift position in a state of being fitted into any one of the plurality of valley parts of the shift switching member;

a motor including a rotor and a stator and driving the shift switching member;

a speed reduction mechanism section that rotates the shift switching member in a state in which a rotation speed transmitted from the motor is reduced;

a rotor rotational angle sensor that detects a rotational angle of the rotor; and

an output shaft rotational angle sensor that detects a rotational angle of the shift switching member, wherein

a width of a backlash included in the speed reduction mechanism section is detected based on an output value of the output shaft rotational angle sensor and an output value of the rotor rotational angle sensor while moving the positioning member so as to continuously pass through the plurality of the valley parts by moving in one direction without reciprocating to another direction while passing through the plurality of valley parts, and

the rotational angle of the rotor corresponding to a center of the backlash is calculated based on the detected width of the backlash, and the rotational angle of the motor corresponding to the center of the backlash is acquired based on association between the calculated rotational angle of the rotor corresponding to the center of the backlash and the output value of the output shaft rotational angle sensor corresponding to a valley bottom of the valley part.

2. The shift device according to claim 1 , wherein

the width of the backlash included in the speed reduction mechanism section is detected based on the output value of the output shaft rotational angle sensor and the output value of the rotor rotational angle sensor in a movement section until the positioning member moves from the valley bottom of the valley part to a top portion of a peak part of the shift switching member.

3. The shift device according to claim 1 , wherein

the width of the backlash is detected based on the output value of the output shaft rotational angle sensor and the output value of the rotor rotational angle sensor in a movement section when the motor is rotated in a first direction and when the motor is rotated in a second direction opposite to the first direction.

4. The shift device according to claim 3 , wherein

a difference between a first estimated value of the rotational angle of the rotor with respect to the output shaft rotational angle sensor calculated from the output value of the output shaft rotational angle sensor and the output value of the rotor rotational angle sensor in a plurality of the movement sections when the motor is rotated in the first direction, and a second estimated value of the rotational angle of the rotor with respect to the output shaft rotational angle sensor calculated from the output value of the output shaft rotational angle sensor and the output value of the rotor rotational angle sensor in the plurality of movement sections when the motor is rotated in the second direction is detected as the width of the backlash, and

a central value of the width of the backlash is defined as the center of the backlash.

5. The shift device according to claim 1 , wherein

an end portion side valley part disposed at a most end portion side of the plurality of valley parts included in the shift switching member is provided with a wall portion that suppresses the positioning member from moving beyond the end portion side valley part, and

the positioning member is moved so as to continuously pass through the plurality of valley parts so as not to collide with the wall portion.

6. The shift device according to claim 1 , wherein

the speed reduction mechanism section includes a driving-side member provided on a side of the motor that drives the shift switching member and a driven-side member provided on a side of the shift switching member and is rotated with a rotation of the driving-side member,

a predetermined amount of a backlash is provided between the driving-side member and the driven-side member in advance, and

a width of the predetermined amount of the backlash provided between the driving-side member and the driven-side member is detected by moving the positioning member so as to continuously pass through the plurality of valley parts.

7. The shift device according to claim 4 , wherein

the first estimated value is calculated by linearly approximating the output value of the rotor rotational angle sensor with respect to the output value of the output shaft rotational angle sensor in the plurality of movement sections when the motor is rotated in the first direction, and

the second estimated value is calculated by linearly approximating the output value of the rotor rotational angle sensor with respect to the output value of the output shaft rotational angle sensor in the plurality of movement sections when the motor is rotated in the second direction.

8. The shift device according to claim 7 , further comprising:

a nonvolatile storage section that stores the linearly approximated first estimated value, the linearly approximated second estimated value, the center of the backlash which is a central value between the linearly approximated first estimated value and the linearly approximated second estimated value, and the output value of the output shaft rotational angle sensor and the output value of the rotor rotational angle sensor corresponding to the center of the backlash.