SMALL DIAMETER CYLINDRICAL AIR MOTOR FOR DRIVING GRINDERS AND THE LIKE

摘要

The air motor has substantially the size of a standard fountain pen and includes an extruded outer cylindrical casing formed with a circular cross-section eccentric inner surface which has annular grooves in its forward part and a smooth surface, substantially coincident with the bases of the grooves, in its rear part. The grooves constitute air supply and exhaust passages, a retainer groove and a pin groove. A front retainer closes the forward end of the casing and has a tongue projecting into the retainer groove to maintain a predetermined angular orientation in the casing, and a rear retainer is seated against the ribs defining the grooves in the forward portion of the casing and has a tongue projecting into the retainer groove to maintain a relative angular orientation with respect to the front retainer. A motor cylinder is mounted in the casing between the two retainers and has air supply and exhaust ports communicating with the air supply and exhaust passages, respectively. A vane type rotor is rotatably supported in the two retainers, through bearings, and is eccentric to the motor cylinder. The forward end of the rotor is formed with a shaft by means of which a grinder or another tool can be secured to the rotor. The portion of the casing rearwardly of the rear retainer constitutes an air supply and control chamber in which there is an air filter means, and the air passing through the filter means flows through supply passages in the rear retainer into the air supply passage. A connection is provided at the rear of the casing for connecting the air motor to a source of air under pressure, and a manually operable grip threaded on this connection controls the supply of air under pressure to the supply and control chamber. In a modification of the air motor, the exhaust air flows rearwardly along the exterior surface of the motor cylinder and through sound absorbing means to exhaust ports leading to the atmosphere or to an exhaust line.