Patent ID: 6957594

Claim:
A starter for starting an engine by transmitting a rotation force of a motor to a ring gear through a pinion, the starter comprising: an output shaft rotated with an operation of the motor; a cylindrical tube engaging with an outer peripheral surface of the output shaft to be slidable in an axial direction through a bearing fitted in the tube, the cylindrical tube having a first and second ends, the first end supporting the pinion and being closed to define an enclosed space between the first end and an end of the output shaft; and a one-way clutch for transmitting a rotation of the output shaft to the tube, wherein: the tube has a ventilation groove on an inner cylindrical surface to communicate the enclosed space with a space defined in a proximity of the second end of the tube, the ventilation groove being formed into a helical shape twisted about an axis of the tube, the ventilation groove is twisted in a direction opposite to a rotation direction of the tube from the second end toward the first end of the tube, the bearing is press-fitted to the inner cylindrical surface of the tube, the ventilation groove is formed on the inner cylindrical surface of the tube and is located on a radially outside of the bearing, the ventilation groove defines a groove first end that is open on the inner cylindrical surface axially between the first end of the tube and an end of the bearing and a groove second end that is open on the inner cylindrical surface axially between the second end of the tube and an opposite end of the bearing, the ventilation groove has a first end and second end, and the first and second ends are situated at circumferentially different positions in a cylindrical surface area of less than 180 degrees, the first and second ends of the groove are situated without overlapping in the circumferential direction, and the bearing is a wrapping bearing formed by rounding substantially a rectangular-shaped plate into a cylindrical shape.