Patent ID: 8240624

Claim:
A piston position detecting device of a fluid pressure cylinder for detecting an operating position of a piston moving back and forth in the inside of a cylinder tube in a direction of a cylinder axis line, using a magnet mounted to the piston and a position sensor attached to the cylinder tube, comprising: the position sensor; a fixing screw that attaches the position sensor to an outer periphery of the cylinder tube through a sensor attachment bracket that comes into contact with the outer periphery; a nut plate into which the fixing screw is screwed; and a protecting cover that is disposed so as not to come into contact with a head of the fixing screw and covers the position sensor and the whole head of the fixing screw, wherein the nut plate is formed of a same member as the protecting cover in a part of the protecting cover, the position sensor and the protecting cover are configured to be concurrently mounted to the cylinder tube using the fixing screw through an intermediary of the sensor attachment bracket, and in addition, when the position sensor is position-adjusted in a state that the fixing screw is loosened, the protecting cover is enabled to be displaced in the direction of the cylinder axis line together with the position sensor in a state of covering the position sensor, and wherein the protecting cover is provided as a member separate from the sensor attachment bracket and includes a driving hole through which a tool for turning the fixing screw is inserted into an inside of the protecting cover and a hole cover to open/close the driving hole, one end of the hole cover being connected freely pivotably to the protecting cover with a rivet, the hole cover being pivotably driven with the rivet, and the hole cover being displaceable to a hole closing position in which the driving hole is covered or to a hole opening position in which the driving hole is exposed.