Patent ID: 6257117
Filing Date: 2001-07-10
Classification: F15B

Abstract:
A cylinder apparatus having a configuration with an overall outer appearance of having a single-rod cylinder, comprising:a cylinder tube, with an annular protruding zone formed at an intermediate position therein in the longitudinal direction of an inner peripheral surface thereof, providing division into a front cylinder chamber and a rear cylinder chamber,an annular disc part in the front cylinder chamber fitted into said front cylinder chamber and a annular tube part being fitted into the protruding zone;an operating piston rod fitted into a hole formed in the center of said annular disc part;a rotation-stopping mechanism that stops rotation within cylinder tube; anda valve opening/closing bar, provided upright on a surface of a rod cover side of said annular disc part, said annular disc part being fitted into said cylinder chamber of said rear cylinder chamber, and fitted loosely into said annular tube part of said primary-side piston, with a gap therebetween, whereinan internal peripheral surface of an inward-facing flange formed on the inside of said front end of the annular tube part has a rod of said operating piston rod loosely fit therewithin with a gap therebetween,on a common internal peripherial surface of said annular disc part and said annular tube part, a secondary side piston is provided and fit within the piston of the operating piston rod,because the cylinder tube has formed on it a protruding zone, said cylinder chamber formed by the internal peripheral surface of the cylinder tube, the annular disc part of the primary side piston, and the annular tube part is either made an air chamber that communicates with the outside, or a fluid cylinder chamber that is connected at all times to the drain side, a fluid path being formed by communication between said cylinder chamber on said rod cover side from said primary-side piston in said front cylinder chamber and said cylinder chamber enclosed by said internal peripheral surface of said cylinder tube and the end surfaces of said secondary-side piston disc part and annular tube part and primary-side piston annular tube part, by means of a relief valve therebetween, said relief valve being changed from the closed condition to the open condition either by a prescribed fluid pressure or by a mechanical force from said valve opening/closing bar of the primary-side piston.