Coaxial engine starter

Abstract

An engine starter comprising an electric motor having a hollow armature rotary shaft, a solenoid switch for energizing the electric motor and having a push rod extending into the hollow armature rotary shaft, an output rotary shaft having a pinion disposed on a front end thereof, the output rotary shaft being axially slidable relative to the armature rotary shaft to move the pinion into and out of engagement with an engine ring gear. A clutch outer member of an over-running clutch unit is mounted on the output rotary shaft and is connected to the electric motor for being rotated thereby, and a clutch inner member driven by the clutch outer member through a plurality of rollers is provided with helical splines on its inner circumferential surface. In order to transmit a rotational force from the clutch inner member to the output rotary shaft through splines, a ring member having teeth on its outer circumference and in engagement with the helical splines of the clutch inner member, and a stopper for limitting axial movement of the ring member on the output rotary shaft beyond the stopper are disposed. The pinion may be integral with the output rotary shaft, and the output rotary shaft may be axially slidably and relatively rotatably supported within the hollow armature shaft through a bearing. The output rotary shaft may have a large-diameter portion having formed on its outer circumference outer helical splines which are in mesh with inner helical splines in the clutch inner member of the over-running clutch. Alternatively, the pinion may be snuggly fitted and secured to a small-diameter end portion of the output rotary shaft.