Patent ID: 7005766

Claim:
A linear actuator comprising: a stator assembly shaped into a cylinder defining a hollow, the stator assembly including a plurality of windings, a plurality of stator yokes each having an array of pole teeth which define an inner circumference of the stator assembly and which are excited by each of the windings, and a yoke support member formed of resin by injection-molding, and integrally supporting the windings and the stator yokes; a rotor assembly shaped into a hollow-cylinder, and rotatably housed in the hollow of the stator assembly, the rotor assembly including a ring-shaped magnet constituting an outer circumference of the rotor assembly, and opposing the pole teeth of the stator assembly with a clearance therebetween, and a female screw disposed at an inner circumference of the rotor assembly; a rear end cap positioned at a rear end of the stator assembly, integrally formed of the resin injected simultaneously when injection-molding the yoke support member of the stator assembly, and rotatably supporting a rear end of the rotor assembly; a front end protrusion positioned at a front end of the stator assembly, shaped into a ring concentric with the stator assembly, having an inner diameter larger than a diameter of the hollow of the stator assembly, and integrally formed of the resin injected simultaneously when injection-molding the yoke support member of the stator assembly; a front bearing defining an opening at its center, detachably fitted into the front end protrusion, and rotatably supporting a front end of the rotor assembly; an output shaft having a male screw which is formed at a rearward portion thereof and which engages threadedly with the female screw of the rotor assembly, the output shaft going through the opening of the front bearing and through the rotor assembly; and a front end cap disposed at the front end of the stator assembly, having a hole for supporting movably and guiding the output shaft, and attached to the stator assembly so as to be fitted onto an outer circumference of the front end protrusion.