US 4,552,055 AGranted

Power cylinder with internally mounted position indicator

AssigneePrince Manufacturing, Inc.

InventorW. John Foxwell

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Abstract

A fluid pressure actuator is disclosed of the piston and cylinder type, in which an internally mounted transducer is incorporated for providing an electrical output signal corresponding to the position of the piston in the cylinder. The transducer is disclosed as a rotary potentiometer having a disc or drum element provided with conductive plastic tracks and a rotary wiper element rotated in correspondence with the linear travel of the piston in the cylinder by a connected cam rod slidably mounted within the piston rod and caused to rotate in one embodiment by means of a cam bushing engaging the cam rod, and in other embodiments by three converging spring biased plungers carried in the piston engaging respective sides of a hexagonal shaped cam rod. Other disclosed arrangements include a reduction drive interposed between the cam element and the rotary wiper to enable a multi-turn cam element to be employed with a single turn potentiometer disc, and a multi-turn drum potentiometer having a wiper element driven by the cam rod engaging a helical thread form to be axially advanced by the piston motion.

Claims17

Dependent claims

An improvement in a power cylinder assembly comprising an elongated cylinder having opposite ends, end cap means closing off said opposite ends of said cylinder, a piston and rod assembly mounted in said cylinder for longitudinal reciprocating movement therein, said piston and rod assembly including a piston and a piston rod affixed to said piston;

said improvement comprising:
an elongated cam rod having a camming surface thereon;
mounting means connected to said cam rod for holding said cam rod against longitudinal movement within said cylinder and for permitting rotational movement of said cam rod;
at least one camming element carried by said piston and rod assembly, said camming element being in cooperative engagement with said camming surface of said cam rod for causing rotation of said cam rod about its longitudinal axis to a plurality of rotational positions corresponding to the longitudinal position of said piston and rod assembly in response to reciprocating longitudinal movement of said piston and rod assembly relative to said cam rod;
rotary potentiometer means mounted within said cylinder and having a rotary wiper element adapted to rotate to a plurality of positions for providing a variable resistance;
mechanism drivingly interconnecting said cam rod to said wiper element for causing said wiper element to rotate to a plurality of positions in response to rotation of said cam rod;
said piston rod including an interior bore formed therein and extending along the longitudinal axis thereof, said cam rod having one end thereof extending into said bore for telescopic sliding movement therein;
said rotary potentiometer means being positioned completely within said cylinder and being located completely externally of said interior bore of said piston rod.

5 more elements

Dependencies are inferred from the claim text.