Patent ID: 7223093

Claim:
An injection device for injecting resin by advancing an injection screw driving body, whereby rotational movement of an electric motor is converted to linear movement of the injection screw driving body to advance the injection screw driving body, the injection device comprising: an injection screw operatively-coupled to said injection screw driving body; a ball screw shaft, having a shaft end portion and a ball screw shaft spline that is disposed on an outer periphery of said shaft end portion, operatively-coupled to said injection screw driving body via a nut member; an electric motor having a motor shaft; a bearing sleeve for coupling said ball screw shaft to said motor shaft, the bearing sleeve having: an inner diameter for engaging said shaft end portion of the ball screw shaft, a flange integrally formed on an outer periphery of the bearing sleeve for releasably attaching said bearing sleeve to an end face of said motor shaft, a rear portion disposed at the rear of the flange that is adapted to fit into a recess provided in the face of said motor shaft, an inner spline disposed at an inner periphery of the bearing sleeve, and an annular groove provided at the inner periphery near an opening for said shaft end portion of the ball screw shaft; and a ring member that is disposable in said annular groove, for air-tightly sealing a clearance formed between the ball screw shaft and the bearing sleeve, wherein the bearing sleeve is detachably mounted to said end face of the motor shaft by fitting the rear portion of said bearing sleeve into the recess and fastening the flange to said end face of the motor shaft such that said bearing sleeve spline serves as a spline for the motor shaft.