GB669308A - Improvements in or relating to damping devices for governors of hydraulic apparatus or systems - Google Patents

Abstract

669,308. Fluid-actuated valves with dashpots. MARINE, O. May 25, 1948 [June 28, 1947], No. 14149/48. Class 135 [Also in Groups XXVIII and XXXII] A valve comprises a closure member 20 positioned relatively to its seat 19 by a piston 18 subjected to the pressures on opposite sides of a restriction 17 to maintain a constant rate of liquid flow at 16 beyond the restriction. The piston is loaded by a spring 2 and hunting is prevented by a dashpot device comprising a piston valve 4 and a piston 3, the spring acting between the piston and the head 1 of the valve and being initially compressed. The piston is slidable on the valve and in a cylinder 7 which has a connection 5 with the inlet line 15 of the flow controlling valve, and an exhaust connection 6. A liquid filled chamber 8 in the cylinder is connected to the interior of the piston 3 by a passage having a throttle 9. Upward movement of the piston 18 compresses the spring 2 and moves the valve 4 to connect the chamber 8 to exhaust, whereby the piston 3 follows the valve at a speed determined by the throttle 9 to close the valve and return the spring to its initial compression. Downward movement of the piston 18 causes extension of the spring and movement of the valve 4 to connect the chamber 8 to the inlet whereby the piston 3 slowly follows the valve to recompress the spring and cut-off the inlet.