Motor actuator

1. A motor actuator comprising:

a box-shaped housing including a first case and a second case, which are overlapped with each other, and a fastening unit, which fastens the first case and the second case; and

a plurality of output mechanisms accommodated in the housing, wherein each of the plurality of output mechanisms includes a motor and a plurality of deceleration gears that decelerate and output rotation of the motor, the motor is supported by the housing, and the plurality of deceleration gears include a worm that is attached to a rotation shaft of the motor and transmits rotation of the motor, a circular plate-shaped deceleration gear that is directly engaged with the worm to decelerate and transmit the rotation of the motor from the worm, and a circular plate-shaped final stage deceleration gear rotatably supported by the housing to further decelerate and output the rotation of the motor from the circular plate-shaped deceleration gear,

wherein the fastening unit is arranged in a first fastening unit formation range, the first fastening unit formation range is a range formed by connecting centers of gravity of the plurality of motors and rotation centers of the plurality of final stage deceleration gears as viewed from a first direction, along which a rotation axis of the final stage deceleration gear extends,

wherein the circular plate-shaped deceleration gears and the final stage deceleration gears of the plurality of deceleration gears are arranged so that all rotation axes thereof extend along the first direction in parallel,

wherein the plurality of final stage deceleration gears are distanced from each other with respect to a second direction that is perpendicular to the first direction, and

wherein the fastening unit includes a first member disposed on the first case and a second member disposed on the second case, wherein the first member and the second member are configured to fasten the first case and the second case by at least one of thread-fastening and snap-fitting.

2. The motor actuator according to claim 1 , wherein the fastening unit is arranged in a second fastening unit formation range, and the second fastening unit formation range, as viewed from the first direction, is a range that includes the first fastening unit formation range and is formed by connecting the contours of the plurality of motors and rotation centers of the plurality of final stage deceleration gears.

3. The motor actuator according to claim 1 , wherein the fastening unit is arranged in a third fastening unit formation range, and the third fastening unit formation range, as viewed from the first direction, is a range that includes the first fastening unit formation range and is formed by connecting centers of gravity of the plurality of motors and the contours of the plurality of final stage deceleration gears.

4. The motor actuator according to claim 1 , wherein the housing has an outer surface on which is arranged an outer fastening unit that fastens the first case and the second case.

5. The motor actuator according to claim 1 , wherein the fastening unit includes

a first fastening support arranged on either one of the first case and the second case, wherein the first fastening support includes a threaded hole recessed along a recess direction;

a second fastening support arranged on the other one of the first case and the second case, wherein the second fastening support includes a through hole that communicates the threaded hole and an exterior of the housing, the second fastening support contacts the first fastening support along the recess direction; and

a fastening screw that extends through the through hole to be joined with the threaded hole to fasten the first fastening support and the second fastening support.

6. The motor actuator according to claim 5 , wherein the second fastening support includes an accommodation recess that accommodates a head of the fastening screw.

7. The motor actuator according to claim 5 , wherein

the first fastening support and the second fastening support project along an opposing direction of the first case and the second case toward each other inside the housing;

the fastening unit includes a labyrinth structure portion located between a distal end of the first fastening support and a distal end of the second fastening support; and

the labyrinth structure portion is formed to form a complicated passage that extends from an inner side of the second fastening support through between the first fastening support and the second fastening support and into the housing.

8. The motor actuator according to claim 1 , wherein

the fastening unit includes

a first fastening support arranged on either one of the first case and the second case and including an engagement hook, and

a second fastening support arranged on the other one of the first case and the second case, wherein the second fastening support includes an inner circumferential surface, which defines a through window hole extending along an opposing direction toward the first fastening support, and an engagement projection formed on the inner circumferential surface; and

wherein the engagement hook is snap-fitted and engaged with the engagement projection.

9. The motor actuator according to claim 8 , wherein the engagement hook includes a distal end arranged inside the through window hole.

10. The motor actuator according to claim 8 , wherein

the first fastening support includes a sandwiching surface that contacts an end face of the second fastening support closer to the first fastening support in the opposing direction, and

an end of the second fastening support closer to the first fastening support is sandwiched by the engagement hook and the sandwiching surface.