Power cylinder with internally mounted position indicator

Claim 2

In combination with a fluid pressure actuator of the piston and cylinder type comprising a cylinder and a piston assembly including a piston slidably mounted within said cylinder, a pair of end caps closing off either end of said cylinder to thereby define a fluid pressure chamber adjacent to each end cap on either side of said piston assembly, each end cap having an end face abutting against said piston in respective extreme positions of said piston in said cylinder; one of said fluid pressure chambers including a cavity formed between said piston and one of said end caps with said piston in abutment thereagainst, pressure port means for selectively pressurizing said one of said fluid pressure chambers, said piston assembly further including a piston rod affixed to said piston and extending through the other of said end caps: an indicating arrangement comprising: a bore formed into said piston assembly extending axially away from said one end cap, a cam rod having one end slidably fit into said bore formed into said piston assembly, said cam rod other end extending axially away from said piston assembly towards said one end cap; means axially fixing said cam rod element with respect to said cylinder whereby causing said one end of said cam rod to be reciprocated within said bore upon reciprocal stroking of said piston assembly in said cylinder; at least one camming element carried by said piston assembly in engagement with a surface of said cam rod element causing rotation of said cam rod upon reciprocation of said piston assembly in said cylinder; rotary potentiometer means mounted within said cavity including a rotary wiper element; electrical connection means connected to said rotary potentiometer means and means providing a variable resistance in correspondence with the rotary position of said rotary wiper element; means drivingly connecting the other end of said cam rod and said rotary potentiometer wiper element producing corresponding rotation of said rotary wiper element upon rotation of said cam rod, whereby an electrical signal corresponding to the position of said piston assembly in said cylinder may be generated by said rotary potentiometer means.

Claim 3

The fluid pressure actuator according to claim 1 wherein said rotary potentiometer means includes a track element having at least one conductive plastic resistive track formed thereon.

Claim 4

The fluid pressure actuator according to claim 1 wherein said cam rod comprises a spirally twisted rod, and wherein said at least one camming element comprises a cam bushing formed with an angularly shaped bore and wherein said cam rod is formed with a complementary shape passing therethrough said shape preventing relative rotation therebetween.

Claim 5

The fluid pressure actuator according to claim 1 wherein said means drivingly connecting said cam rod and said potentiometer wiper element comprise a coupling member affixed to said cam rod connected to rotate together therewith, and wherein said spirally twisted rod is formed with less than a 360° twist along its length.

Claim 6

The fluid pressure actuator according to claim 1 wherein said means drivingly connecting said potentiometer wiper element and said cam rod comprises gearing means interposed between said cam rod and said rotary wiper element, said means providing a reduced rate of rotation of said wiper element in response to rotation of said cam rod.

Claim 7

The fluid pressure actuator according to claim 5 wherein said gearing means comprises a gear reduction spur gearing including a spur gear affixed to said cam rod element and a second spur gear in mesh with said cam rod element spur gear and also including a shaft having said second spur gear affixed thereto and to said wiper element.

Claim 8

The fluid pressure actuator according to claim 5 wherein said gearing means comprises a planetary gearing means aligned with the axis of said cam rod, further including a sun gear affixed to said cam rod with a plurality of planetary gears arranged about said sun gear in mesh therewith, a planetary carrier supporting said plurality of planetary gears and a ring gear affixed to one of said end caps of said fluid pressure actuator, said planetary gears also in mesh with said ring gear; and, further including means affixing said wiper element to said planetary carrier to produce a reduced rotational rate thereof with respect to said cam rod.

Claim 9

The fluid pressure actuator according to claim 5 wherein said cam rod comprises a multi-turn spiral and further including positive stop means limiting the stroke of said piston in either direction of said movement within said cylinder; and wherein during said stroking motion of said piston and cylinder, said cam rod is rotated a plurality of revolutions and wherein said gearing means reduces said rotation of said cam rod to less than a single revolution of said wiper element.

Claim 10

In combination with a fluid pressure actuator of the piston and cylinder type comprising a cylinder and a piston assembly including a piston slidably mounted within said cylinder, a pair of end caps closing off either end of said cylinder to thereby define a fluid pressure chamber adjacent to each end cap on either side of said piston assembly, each end cap having an end face abutting against said piston in respective extreme positions of said piston in said cylinder; one of said fluid pressure chambers including a cavity formed between said piston and one of said end caps with said piston in abutment thereagainst, pressure port means for selectively pressurizing said one of said fluid pressure chambers, said piston assembly further including a piston rod affixed to said piston and extending through the other of said end caps; an indicator arrangement comprising: a bore formed into said piston assembly extending axially away from said one end cap, a cam rod having one end slidably fit into said bore formed into said piston assembly, said cam rod other end extending axially away from said piston assembly towards said one end cap; means axially fixing said cam rod element with respect to said cylinder whereby causing said one end of said cam rod to be reciprocated within said bore upon reciprocal stroking of said piston assembly in said cylinder; a plurality of radially converging plungers carried by said piston assembly and means biasing each of said plungers into engagement with a surface of said cam rod element causing rotation of said cam rod upon reciprocation of said piston assembly in said cylinder; rotary potentiometer means mounted within said cavity including a rotary wiper element; electrical connection means connected to said rotary potentiometer means and means providing a variable resistance in correspondence with the rotary position of said rotary wiper element; means drivingly connecting the other end of said cam rod and said rotary potentiometer wiper element producing corresponding rotation of said rotary wiper element upon rotation of said cam rod, whereby an electrical signal corresponding to the position of said piston assembly in said cylinder may be generated by said rotary potentiometer means.

Claim 11

In combination with a fluid pressure actuator of the piston and cylinder type comprising a cylinder and a piston assembly including a piston slidably mounted within said cylinder, a pair of end caps closing off either end of said cylinder to thereby define a fluid pressure chamber adjacent to each end cap on either side of said piston assembly, each end cap having an end face abutting against said piston in respective extreme positions of said piston in said cylinder; one of said fluid pressure chambers including a cavity formed between said piston and one of said end caps with said piston in abutment thereagainst, pressure port means for selectively pressurizing said one of said fluid pressure chambers, said piston assembly further including a piston rod affixed to said piston and extending through the other of said end caps; an indicator arrangement comprising: a bore formed into said piston assembly extending axially away from said one end cap, a cam rod having one end slidably fit into said bore formed into said piston assembly, said cam rod other end extending axially away from said piston assembly towards said one end cap; means axially fixing said cam rod element with respect to said cylinder whereby causing said one end of said cam rod to be reciprocated within said bore upon reciprocal stroking of said piston assembly in said cylinder; a plurality of radially converging plungers carried by said piston assembly and means biasing each of said plungers into engagement with a surface of said cam rod element causing rotation of said cam rod upon reciprocation of said piston assembly in said cylinder; rotary potentiometer means mounted within said cavity including a rotary wiper element; electrical connection means connected to said rotary potentiometer means and means providing a variable resistance in correspondence with the rotary position of said rotary wiper element; means drivingly connecting the other end of said cam rod and said rotary potentiometer wiper element producing corresponding rotation of said rotary wiper element upon rotation of said cam rod, whereby an electrical signal corresponding to the position of said piston assembly in said cylinder may be generated by said rotary potentiometer means.

Claim 12

The fluid pressure actuator according to claim 9 wherein said cam rod is formed with a plurality of flat sides, and wherein each of said plungers is biased into engagement with a respective one of said plurality of flat sides.

Claim 13

The fluid pressure actuator according to claim 9 wherein each of said plungers is slidably disposed in a bore formed in said piston.

Claim 14

The fluid pressure actuator according to claim 11 wherein said means biasing each of said plungers into engagement with said cam rod comprises a compression spring disposed in each of said bores.

Claim 15

The fluid pressure actuator according to claim 10 wherein said cam rod comprises a spirally twisted hexagonal shaped rod.

Claim 16

In combination with a fluid pressure actuator of the piston and cylinder type comprising a cylinder and a piston assembly including a piston slidably mounted within said cylinder, a pair of end caps closing off either end of said cylinder to thereby define a fluid pressure chamber adjacent to each end cap on either side of said piston assembly, each end cap having an end face abutting against said piston in respective extreme positions of said piston in said cylinder; one of said fluid pressure chambers including a cavity formed between said piston and one of said end caps with said piston in abutment thereagainst, pressure port means for selectively pressurizing said one of said fluid pressure chambers, said piston assembly further including a piston rod affixed to said piston and extending through the other of said end caps; an indicator arrangement comprising: a bore formed into said piston assembly extending axially away from said one end cap, a cam rod having one end slidably fit into said bore formed into said piston assembly, said cam rod other end extending axially away from said piston assembly towards said one end cap; means axially fixing said cam rod element with respect to said cylinder whereby causing said one end of said cam rod to be reciprocated within said bore upon reciprocal stroking of said piston assembly in said cylinder; at least one camming element carried by said piston assembly in engagement with a surface of said cam rod element causing rotation of said cam rod upon reciprocation of said piston assembly in said cylinder; rotary potentiometer means mounted within said cavity including a rotary wiper element; electrical connection means connected to said rotary potentiometer means and means providing a variable resistance in correspondence with the rotary position of said rotary wiper element, said rotary potentiometer means including a drum mounted with its axis in alignment with said cam rod and wherein said cam rod extends through said drum and is received in a bore formed into said other of said end caps; means drivingly connecting the other end of said cam rod and said rotary potentiometer wiper element producing corresponding rotation of said rotary wiper element upon rotation of said cam rod, whereby an electrical signal corresponding to the position of said piston assembly in said cylinder may be generated by said rotary potentiometer means.

Claim 17

In combination with a fluid pressure actuator of the piston and cylinder type comprising a cylinder and a piston assembly including a piston slidably mounted within said cylinder, a pair of end caps closing off either end of said cylinder to thereby define a fluid pressure chamber adjacent to each end cap on either side of said piston assembly, each end cap having an end face abutting against said piston in respective extreme positions of said piston in said cylinder; one of said fluid pressure chambers including a cavity formed between said piston and one of said end caps with said piston in abutment thereagainst, pressure port means for selectively pressurizing said one of said fluid pressure chambers, said piston assembly further including a piston rod affixed to said piston and extending through the other of said end caps; an indicator arrangement comprising: a bore formed into said piston assembly extending axially away from said one end cap, a cam rod having one end slidably fit into said bore formed into said piston assembly, said cam rod other end extending axially away from said piston assembly towards said one end cap; means axially fixing said cam rod element with respect to said cylinder whereby causing said one end of said cam rod to be reciprocated within said bore upon reciprocal stroking of said piston assembly in said cylinder; at least one camming element carried by said piston assembly in engagement with a surface of said cam rod element causing rotation of said cam rod upon reciprocation of said piston assembly in said cylinder; rotary potentiometer means mounted within said cavity including a rotary wiper element; electrical connection means connected to said rotary potentiometer means and means providing a variable resistance in correspondence with the rotary position of said rotary wiper element, said rotary potentiometer means including a drum mounted with its axis in alignment with said cam rod and wherein said cam rod extends through said drum and is received in a bore formed into said other of said end caps; means drivingly connecting the other end of said cam rod and said rotary potentiometer wiper element producing corresponding rotation of said rotary wiper element upon rotation of said cam rod, whereby an electrical signal corresponding to the position of said piston assembly in said cylinder may be generated by said rotary potentiometer means.

Claim 18

The fluid pressure actuator according to claim 14 wherein said rotary potentiometer wiper element extends into wiping engagement with the interior surface of said drum.

Claim 19

The fluid pressure actuator according to claim 15 wherein said rotary potentiometer drum is formed with a conductive spiral track and wherein said wiper element is mounted to be advanced axially upon rotation of said cam rod while maintaining engagement with said spiral track, whereby a multi-turn potentiometer is provided.

Claim 20

The fluid pressure actuator according to claim 16 wherein said wiper element is carried by a carrier element slidably mounted on said cam rod end portion, and wherein said drum is formed with a helical track engaged by said carrier element to cause said axial advance of said wiper element upon rotation of said cam rod.