GB512819A - Improvements in automatically-acting relief valves - Google Patents

Abstract

512,819. Relief valves, LAMB, J. March 25, 1938, No. 9187. [Class 135] A relief valve particularly adapted for use in the starting-air systems of Diesel and similar internal-combustion engines is adapted to open widely to relieve abnormal pressure and return automatically to its closed position when the said pressure has been removed. In the form shown in Fig. 1 the valve comprises a piston part a subject to inlet pressure admitted through a conduit b and a larger disc part d normally engaging a chamfered seat m. The part d is loaded by a light spring r and by fluid pressure admitted through a restricted orifice p. When the inlet pressure becomes excessive the valve part d is moved off its seat allowing the loading pressure to escape to atmosphere through ports n so permitting the inlet pressure to move the valve rapidly to its full open position. The excess pressure escapes through the ports k and when reduced to normal the spring r reseats the disc valve and allows loading pressure to build up in the chamber g. A projection s on the valve co-operates with a recess t to cushion the opening movement. In a modification the valve member is formed with a recess adapted to work over a hollow ported boss. The loading fluid is led to the interior of the boss and the ports are so arranged that the supply is interrupted when the valve moves to its open position. In the form shown in Fig. 4, which is adapted to serve as a bye-passing relief valve for a pump, a similar arrangement of ported boss s<2> and recess t<2> is used. The hollow piston is formed with a pair of spaced chamfered flanges w, d' adapted to engage seats on the casing when the valve is used, the flange w being provided to prevent the escape of pressure fluid from the outlet conduit v. When the valve a<1> is lifted from its seat by abnormal pressure the flange d<1> also moves away from its seat to vent the loading pressure through the port n<1>. The valve a' may be opened under manual control by closing the cock p<2> and opening the drain cock x.