Patent ID: 8302624

Claim:
A linear valve position measuring apparatus comprising: a rotation supporting housing ( 20 ) installed on a bidirectional hydraulic cylinder ( 10 ); a top supporting plate ( 30 ) positioned above, spaced apart from and assembled with the rotation supporting housing ( 20 ) in a single body by a plurality of supporting poles ( 31 , 32 ); a rotation sleeve ( 40 ) positioned to surround the outside of an upper piston rod ( 12 ) of the bidirectional hydraulic cylinder ( 10 ), top and bottom ends of the rotation sleeve ( 40 ) being respectively rotatably connected to the rotation supporting housing ( 20 ) and the top supporting plate ( 30 ), and the outer circumference of the rotation sleeve ( 40 ) including a spiral groove ( 42 ) formed to pass through the inside and outside of the rotation sleeve ( 40 ); a guide pin ( 50 ) with one end being connected to an upper part of the upper piston rod ( 12 ) and the other end passing through the spiral groove ( 42 ) and protruding outwardly, the guide pin ( 50 ) positioned to pass through a guide space ( 51 ) formed between a pair of the supporting poles ( 32 ) installed to be adjacent to each other, to prevent a rotation movement upon a vertical movement; a potentiometer ( 60 ) installed through a potentiometer securing plate ( 61 ) connected to the top supporting plate ( 30 ), and a variable shaft ( 63 ) positioned under the potentiometer ( 60 ) and connected to the rotation sleeve ( 40 ) in a single body, to output an electrical signal corresponding to a rotation angle of the rotation sleeve ( 40 ); and an ECU (electronic control unit) ( 70 ) to calculate a vertical movement distance of the upper piston rod ( 12 ), by using the electrical signal being output by the potentiometer ( 60 ).