Patent ID: 8443690

Claim:
A speed reduction device for a power seat adapted to be fixed to a seat frame, the speed reduction device comprising: a worm gear coaxially and integrally rotating with an output shaft of a motor: a helical gear meshed with the worm gear and coaxially and integrally rotating with a drive shaft driving a movable portion of the power seat; a casing including a casing body rotatably supporting the worm gear and including a circular-shaped opening portion through which the helical gear is inserted, the casing including a casing cover tightened to the casing body and closing the opening portion of the casing body, the casing being fixed to a housing of the motor; and a motor fixation device including; a first fitting portion provided at the housing and surrounding the output shaft of the motor, a first engagement portion formed at the first fitting portion in a direction perpendicular to the output shaft of the motor, a second fitting portion formed at the casing body and to which the first fitting portion is fitted, a second engagement portion formed at the second fitting portion in a direction perpendicular to the output shaft of the motor and arranged to overlap the first engagement portion in a direction perpendicular to the output shaft of the motor in a case where the first fitting portion is fitted to the second fitting portion, and an engagement projection formed at the casing cover and engaging with the first engagement portion and the second engagement portion in a case where the casing cover is tightened to the casing body.