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A fluid operated actuator comprising a cylinder, a piston and a linkage rod connected to the piston, in which the cylinder is curved through a number of degrees.

대표청구항 ▼

1. A fluid operated actuator comprising a cylinder, a piston and linkage means connected to the piston, and the cylinder being formed from a straight piece of stainless steel tubing bent through substantially 90 degrees.2. The fluid operated actuator as claimed in claim 1 in which the linkage means

1. A fluid operated actuator comprising a cylinder, a piston and linkage means connected to the piston, and the cylinder being formed from a straight piece of stainless steel tubing bent through substantially 90 degrees.2. The fluid operated actuator as claimed in claim 1 in which the linkage means is curved through substantially 90 degrees.3. The fluid operated actuator as claimed in claim 2 in which the linkage means is connected at an outer end to a turning arm mounted on a rotatable shaft.4. The fluid operated actuator as claimed in claim 3 in which the turning arm is mounted under compression means for returning the piston to a bottom of the cylinder at the end of each stroke and rotate the rotatable shaft back to its starting position.5. The fluid operated actuator as claimed in claim 4 in which the cylinder, the turning arm and the compression means are mounted on a base plate so as to prevent lateral or expansional movement between the parts during the operation of the actuator.6. The fluid operated actuator as claimed in claim 5 in which the compression means is a flat spiral spring mounted at an outer end to a spring mounting means provided on the base plate and at an inner end to one of the rotatable shaft and a connection between the turning arm and the rotatable shaft.7. The fluid operated actuator as claimed in claim 1 in which the actuator is a 90 degree valve actuator in which the rotatable shaft actuates a valve.8. The fluid operated actuator as claimed in claim 1 in which the cylinder is a pneumatic cylinder powered by one of pressurized air and dry air.9. The fluid operated actuator as claimed in claim 8 in which air is introduced to a bottom of the cylinder through an aperture.10. The fluid operated actuator as claimed in claim 9 in which the piston is an air-tight seal which moves up the cylinder when the air is introduced, and is returned to the bottom by a spring when the air pressure is reduced.11. The fluid operated actuator as claimed in claim 10 in which lower and upper end elements are provided at each end of the cylinder, and the upper end element having an aperture through which the linkage means can pass.12. The fluid operated actuator as claimed in claim 5 in which the base plate is a circular disk.13. The fluid operated actuator as claimed in claim 12 in which the cylinder is mounted adjacent to an edge of the base plate and the shaft passes substantially through the centre of the base plate.14. The fluid operated actuator as claimed in claim 13 in which a cover is fitted over a top of the valve actuator and to the edge of the base plate.15. The fluid operated actuator as claimed in claim 14 in which the cover is constructed from a transparent material.16. The fluid operated actuator as claimed in claim 11 in which the piston, the linkage means, the turning arm, the shaft, the spring, the base plate, the lower end element and the upper end element are constructed from stainless steel.17. The fluid operated actuator as claimed in claim 1 in which the stainless steel tubing is provided with an internal finish of 25 micro inches or finer.18. The fluid operated actuator as claimed in claim 3 in which the rotatable shaft is provided with two turning arm fixing points disposed at substantially 90 degrees to one another, locking means for securing the rotatable shaft in position on a base plate, and the turning arm can be releasably attached to either fixing point.19. The method of placing under compression a fluid operated actuator as claimed in claim 18, comprising the steps of:mounting the outer end of the coil spring to the spring mounting means on the base plate and the inner end to spring mounting means on the rotatable shaft with the spring under zero compression, mounting the turning arm to the first mounting point provided on the shaft, applying fluid pressure to the cylinder and rotating the shaft through 90 degrees thereby putting the spring under compression, securing the shaft to the base plate with the locking means, releasing the fluid pressure inside the cylinder, disconnecting the turning arm from the shaft, pushing the turning arm, the linkage rod and the piston back through 90 degrees, reconnecting the turning arm to the second mounting point provided on the shaft which is at substantially 90 degrees to the first mounting point, and releasing the shaft from the locking means. 20. A method of placing under compression a fluid operated actuator which includes a cylinder, a piston, a linkage rod, a turning arm, a flat spiral spring and a rotatable shaft, the cylinder is curved through substantially degrees, the linkage rod is connected at an inner end to the piston, the linkage rod is connected at an outer end to the turning arm, the linkage rod is held under compression in use by the flat spiral spring, the shaft is provided with two turning arm fixing points disposed at substantially 90 degrees to one another, the shaft is provided with locking means for securing it in a rotational position, and the turning arm can be realeasably attached to either fixing point comprising the steps of:mounting the flat spiral spring to the shaft absent compression, mounting the turning arm to a first turning arm fixing point, applying pressure to the cylinder to turn the shaft though substantially 90 degrees, securing the shaft in its rotational position with the locking means, releasing the pressure in the cylinder, disconnecting the turning arm from the first turning arm fixing point, pushing the turning arm, the linkage rod and the piston back through 90 degrees, connecting the turning arm to a second turning arm fixing point, and releasing the shaft from the locking means. 21. The fluid operated actuator as defined in claim 1 including a flat spiral spring for holding the linkage rod under compression.22. A fluid operated actuator comprising a cylinder, a piston, a linkage rod, a turning arm and a rotatable shaft; the cylinder being curved through a number of degrees, the linkage rod being connected at an inner end to the piston, the linkage rod being connected at an outer end to the turning arm, the shaft being provided with two turning arm fixing points disposed at substantially 90 degrees to one another, the shaft having locking means for securing the shaft in a selected rotational position, and the turning arm can be releasably attached to either fixing point.