Engine starter

摘要

An engine starter includes a motor that comprises a drive shaft; and a unidirectional rotation clutch system that is helical-splined to the drive shaft. The clutch system includes a clutch inner; a clutch outer; a clutch roller that is interposed between the clutch outer and the clutch inner; and a spring that urges the clutch roller, wherein a compound film is formed on a surface of the clutch roller or surfaces of the clutch outer and the clutch inner.

主权项

1. An engine starter, comprising:
a motor that comprises a shaft of the motor; a reduction mechanism to engage with the shaft of the motor and transmit a driving force to a drive shaft; a unidirectional rotation clutch system that is helical-splined to the drive shaft, the clutch system being movable from an inactive position on a base end side of the drive shaft to an active position on a tip end side of the drive shaft when relative rotation occurs in a predetermined rotating direction from a side of the drive shaft; a pinion gear that connects with the clutch system, and engages with a ring gear on a side of an engine when the clutch system moves to an active position, wherein: the clutch system comprises:
a clutch inner;a clutch outer;a clutch roller that is interposed between the clutch outer and the clutch inner; anda spring that urges the clutch roller, the clutch roller slips causing a frictional heat while engaging with the clutch inner when a torque impacts the drive shaft from the side of the engine, the clutch roller is made of bearing steel, a surface of the clutch roller is quenched and tempered before being gas nitrided so that a compound film is formed on the surface of the clutch roller such that the compound film includes a nitride phase with a surface layer formed as two surface layers (a layer (Fe2N) and a layer (Fe4N)) and an internal phase formed as a diffusion phase (a (Fe+Fe4N) phase), wherein a thickness of the surface layer is 14/18 of a thickness of the compound film, a thickness of the internal phase is 4/18 of the thickness of the compound film, a surface of the clutch inner is not applied to be quenched, tempered and nitrided, and a surface of the clutch outer is not applied to be quenched, tempered and nitrided, and contact between the compound film formed surface of the clutch roller and the surface of the clutch outer and contact between the compound film formed surface of the clutch roller and the surface of the clutch inner is a sliding contact of heterogeneous surfaces so that a friction coefficient between the clutch roller and the clutch outer and a friction coefficient between the clutch roller and the clutch inner caused by the sliding contact is lowered as compared to when the compound film is not formed on the clutch roller.