Abstract: A starter (1) includes a motor unit (3), an output shaft (4) configured to receive a rotational force of the motor unit (3) and rotate, a pinion gear (74) (a pinion mechanism) helically engageable with a ring gear (23) of an engine, a clutch mechanism (5) configured to transmit the rotational force of the output shaft (4) to the pinion gear (74), and an electromagnetic device (9) configured to bias a pressing force toward the ring gear (23) to the clutch mechanism (5) and the pinion gear (74), wherein a plunger spring (91) (a backlash absorption mechanism) configured to bring one end (81a) (a point of action) of a plunger inner part (81) in constant elastic contact with the clutch mechanism (5) is installed at the electromagnetic device (9).

Abstract: Formed in a pinion (74) are pinion-side helical external teeth (74A) that mesh with a ring gear 823), and pinion-side helical internal teeth (74a) that mesh with a pinion inner (71). Formed in the pinion inner (71) are pinion inner-side helical external teeth (73) that mesh with the pinion-side helical internal teeth (74a). The configuration is formed so that when the rotational speed of the pinion (74) is slower than that of the ring gear (23), a thrust load is generated in a direction toward the ring gear (23), and when the rotational speed of the pinion (74) is faster than that of the ring gear (23), a thrust load is generated in a direction away from the ring gear (23).

Abstract: A starter includes an output shaft which rotates by a rotary force applied from the motor unit, a housing in which an end of the output shaft is rotatably supported, and an electromagnetic device configured to apply/shut off current to the motor unit, and biases a suppressing force toward the ring gear to the pinion gear through a clutch mechanism, wherein a load receiving member which abuts one end of the output shaft to receive an axial load generated from the output shaft is installed in the housing.

Abstract: 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.

Abstract: Formed in a pinion (74) are pinion-side helical external teeth (74A) that mesh with a ring gear 823), and pinion-side helical internal teeth (74a) that mesh with a pinion inner (71). Formed in the pinion inner (71) are pinion inner-side helical external teeth (73) that mesh with the pinion-side helical internal teeth (74a). The configuration is formed so that when the rotational speed of the pinion (74) is slower than that of the ring gear (23), a thrust load is generated in a direction toward the ring gear (23), and when the rotational speed of the pinion (74) is faster than that of the ring gear (23), a thrust load is generated in a direction away from the ring gear (23).

Abstract: A starter (1) includes a motor unit (3), an output shaft (4) configured to receive a rotational force of the motor unit (3) and rotate, a pinion gear (74) (a pinion mechanism) helically engageable with a ring gear (23) of an engine, a clutch mechanism (5) configured to transmit the rotational force of the output shaft (4) to the pinion gear (74), and an electromagnetic device (9) configured to bias a pressing force toward the ring gear (23) to the clutch mechanism (5) and the pinion gear (74), wherein a plunger spring (91) (a backlash absorption mechanism) configured to bring one end (81a) (a point of action) of a plunger inner part (81) in constant elastic contact with the clutch mechanism (5) is installed at the electromagnetic device (9).

Abstract: Excellent durability can be achieved by reducing thermal influences of the excessive load from the engine side for a clutch roller (13) in a unidirectional rotation clutch system that is helical-splined to a drive shaft that rotates in response to a driving force of a motor and structured such that the motor driving force can be transmitted while an engine driving force cannot be transmitted when an engine stars, wherein a compound film composed of an external mixed phase and an internal diffused phase is formed on the clutch roller (13) subjected to nitriding by tufftriding with nitrogen being penetrating and diffusing.

Abstract: Excellent durability can be achieved by reducing thermal influences of the excessive load from the engine side for a clutch roller (13) in a unidirectional rotation clutch system that is helical-splined to a drive shaft that rotates in response to a driving force of a motor and structured such that the motor driving force can be transmitted while an engine driving force cannot be transmitted when an engine stars, wherein a compound film composed of an external mixed phase and an internal diffused phase is formed on the clutch roller (13) subjected to nitriding by tufftriding with nitrogen being penetrating and diffusing.

Abstract: 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.

Abstract: An engine starter includes a unidirectional rotation clutch system with a clutch outer having an outer-diameter side cylinder portion, a clutch inner having an inner-diameter side cylinder portion, long shaft-shaped clutch rollers that are long in a drive shaft direction and are installed in wedge spaces formed between the inner and outer-diameter side cylinder portions, and springs that urge the clutch rollers toward wedge portions, wherein at least one of the inner and outer-diameter side cylinder portions includes a wear preventive portion that prevents wearing of the clutch rollers that have turned so as to be in an inclined posture with respect to the drive shaft.