Electromagnetically reciprocating apparatus with adjustable bounce chamber

Claim 1

An electromagnetically reciprocating apparatus comprising: an electromagnet which repeats magnetization and demagnetization for one-half cycle of AC current or for one pulse of DC current; a piston assembly which includes a magnetic material member to be drawn by the electromagnet in a magnetized state, and front and rear pistons disposed before and behind the magnetic material member; front and rear cylinders for supporting the front and rear pistons of the piston assembly wherein the rear cylinder is formed in a housing the inner space of which communicates with the atmosphere; a compression coil spring which is compressed by the piston assembly when said piston assembly is moved in a forward direction by the magnetic action of the magnetized electromagnet, and which moves the piston assembly in a backward direction by a compressed elastic force thereof when the electromagnet is demagnetized; wherein an air hole is provided between a sealed space which is partitioned by a back face off the rear piston in the rear cylinder, and a space which is located behind a back face of the front piston in the front cylinder and is communicated with the outside of the cylinder, the air hole being open at its one side to the sealed space in the rear cylinder in which the compression coil spring is mounted, and being open at its other side to the outer periphery of the rear cylinder and to the inner space of the housing formed in the back face of the front piston in the front cylinder; manually controlled valve means mounted over the air hole for adjusting resonance frequency of a vibration system comprising the piston assembly and the compression coil spring; wherein the valve means comprises: a cap-like valve casing hermetically mounted on the outer end face of an end wall of the housing so as to cause an end face opening of the inner space of the valve casing to cover one side of the air hole, which is located in the rear cylinder side, and the other side of the air hole, which is located in the inner space side of the housing; and a valve body arranged in the inner space of the valve casing so as to be movable between a closed position where communication between one side of the air hole and the other side of the inner space of the housing through the inner space of the valve casing is interrupted, and an open position where communication between one side and the other side of the air hole through the inner space of the valve casing is permitted.