The present invention relates to an electromagnetic fluid operating apparatus, and more particularly relates to apparatus for transporting fluid such as air by piston reciprocation in which a piston with an armature axially reciprocates along a path which lies substantially at a right angle to the magnetic flux generated by a stator core due to alternate operation by electromagnetic attraction and mechanical repulsion.
In a known apparatus of the above-described type, the stator core is accompanied by induction coils connected via a half-wave rectifier to a given AC source and the armature is adapted to reciprocate axially through a magnetic space defined by a pair of confronting magnetic poles of the stator core. Further a mechanical biasing means such as a return spring is provided to return the piston to its initial position when excitation on the stator core is cancelled.
However, almost no electromagnetic fluid operating apparatuses of the above-described type have been welcomed in the practical industrial fields. The reasons for such a poor invasion of the apparatuses into actual market are estimated to be as follows.
As the armature is attracted by electromagnetic force in the direction almost normal to the direction of the line of magnetic induction generated by the stator core, the armature is liable to experience biased load caused by the line of magnetic induction. In order to successfully prevent biased frictional abrasion of coacting sliding surfaces of an apparatus, it is very important to establish highly exact collimations between the armature and the stator core and between the piston and a cylinder bearing the piston. Most of the conventional constructions for the fluid operating apparatuses cannot assure high accuracy in the above-described collimations and, thus, the most conventional fluid operating apparatuses seriously suffer from biased frictional abrasion of the coacting sliding planes, thereby shortening the life cycle thereof.
The piston reciprocates axially in the bearing cylinder at a frequency which is the same as that of the AC currency supplied to the induction coils of the stator core. As is well known, bearing systems for linear or axial reciprocal motion are not so developed as those for rotary motion. So, in order to obtain a fluid operating apparatus of high durability, it is basically necessary to provide a greatly improved bearing system for the reciprocating piston.
Intermittent intake and discharge of the air into and out of the apparatus by virtue of the piston action tends to develop pulsation of the air supplied by the apparatus. For certain uses of the air supplied by the apparatus, it is definitely required that the air supplied should be quite free of pulsation. In order to meet this requirement, it is generally employed in the prior art to insert an air reservoir tank into the connection between the apparatus and the objective to which the air is to be supplied. This leads to additional cost for provision and installation of the reservoir tank and its related parts.
The apparatus includes a number of heat emitting parts such as the induction coils, the stator core, the armature and the piston bearing system. As a result, long continuous use of the apparatus inevitably leads to extremely elevated temperatures of the entire body of the apparatus which may cause early wearing out of the mechanical and/or electrical parts, difficulty in handling of the apparatus by operators and malfunction of operational parts.
It is required that, when any operational part or parts should be replaced, the parts relating to the replacement should easily be disassembled and, after the replacement with new parts, reassembled while retaining initial high collimation between the parts coupled to each other. Constructions of most conventional fluid operating apparatuses cannot beautifully meet this requirement.