Starting electric motor

Claim 1

A starting electric motor, comprising: electric motor means for generating torque to start an engine, said electric motor means being provided with an armature rotary shaft having a shaft extension thereof; overrunning clutch means axially slidably supported on said haft extension, said overrunning clutch means having a clutch outer being spline-engaged with said shaft extension; a frame having an opening thereof for covering said electric motor; first bearing means fixedly fitted in said frame; movable pinion cylinder means slidably mounted on said shaft extension, said movable pinion cylinder means comprising a clutch inner part at a rear portion thereof, which forms a part of said overrunning clutch means, a pinion part at a front portion thereof, which includes a pinion formed on an outer periphery thereof, said pinion being engaged with a ring gear of said engine, and a middle part formed between said clutch inner part and said pinion part, said middle part including a slidably supporting surface at an outer periphery hereof, and being rotatably supported by said first bearing means and being slidably axially moved with respect to said first bearing means, said pinion part going in and out of said frame through said opening, wherein said movable pinion cylinder means having a first inner periphery which forms a relatively large gap between said movable pinion cylinder means and said shaft extension, said first inner periphery extending from said clutch inner part to at least a part of said middle part, and a second inner periphery extending in said pinion part and providing a minute clearance smaller than said relatively large gap; and second bearing means arranged in said relatively large gap and being slidably movable together with said movable pinion cylinder means on said shaft extension.