Cylinder with fiber optical position sensing device
View Patent ↗A fluid-pressure actuated piston/cylinder assembly having a sensor capable of reading at least one indicia marking on a piston rod in order to determine the movement and specific location of the piston rod and cylinder relative to each other. The sensor is housed within a sealing gland that is incorporated into the piston/cylinder assembly and is isolated from the fluid pressure and external elements outside of the assembly. The method of providing a compact, accurate position detecting system for the noted piston/cylinder assembly is also set forth.
1. An apparatus for sensing movement of a first object relative to a second object, the apparatus comprising:
indicia markings formed on the first object;
a sensor capable of reading the indicia markings, the sensor being supported in a radial bore of the second object; and
a slipper element biased into engagement with the first object and spacing the sensor radially away from the first object by a predetermined distance.
2. The apparatus of claim 1 wherein the sensor is a fiber optical sensor.
3. The apparatus of claim 1 wherein the first object is a piston rod of a piston assembly and the second object is a cylinder, the piston assembly and cylinder forming a portion of a fluid pressure operated actuator.
4. The apparatus of claim 1 wherein the sensor is located within a sealing gland, the sealing gland isolating the sensor from working fluid.
5. The apparatus of claim 1 wherein the slipper element is formed from a wear resistant material having a low coefficient of friction.
6. The apparatus of claim 5 wherein an end of the slipper element is shaped so as to conform to a peripheral surface of the first member.
7. An apparatus for sensing movement of a piston assembly relative to a cylinder, the apparatus comprising:
indicia markings formed on a peripheral surface of a rod portion of the piston assembly;
a radial bore extending into a sealing gland portion of the cylinder;
a sensor capable of reading the indicia markings, the sensor being supported in the radial bore; and
a slipper element biased into engagement with the peripheral surface of the rod portion of the piston assembly and spacing the sensor radially away from the indicia by a predetermined distance.
8. The apparatus of claim 7 wherein the sensor is a fiber optical sensor.
9. The apparatus of claim 7 wherein the sensor, when located within the sealing gland portion of the cylinder, is isolated from working fluid located within the cylinder.
10. The apparatus of claim 7 wherein the slipper element is formed from a wear resistant material having a low coefficient of friction.
11. The apparatus of claim 10 wherein an end of the slipper element is shaped so as to conform to a peripheral surface of the first member.