GB615619A - Improvements in or relating to fluid-pressure relay apparatus - Google Patents

Abstract

615,619. Fluid-pressure servo motor-control systems; valves. PAULIN, J. G. Nov. 27, 1944, No. 23610. [A Specification was laid open to inspection under Sect. 91 of the Acts, Jan. 11, 1944.] [Class 135] In a fluid - pressure servomotor-control system, the device to be regulated is acted upon by a bellows in opposition to a spring, and the pressure in the bellows is controlled by a valve device of which the actuating member is adjusted by pressure variations in a primary fluid and by forces transferred from the bellows through the said spring in such manner that the forces acting on the valve-actuating member tend to balance out. On screwing down a hand wheel 11, a graduating spring 8 connected to a diaphragm 2 is compressed and the resultant movement, besides being indicated on scale 13, is transmitted to a bridge member 19. Spring-loaded single beat lift or ball valves 15, 16 have a lost motion tapper connected with the bridge 19. and the valve 16 will be actuated by the abovementioned movement to admit compressed air from a conduit 40 into a chamber 17 and thence through a conduit 44 to another diaphragm chamber 45. The pressure in chamber 17 is also transmitted through 'the apertures housing the legs of the bridge 19 to the lower surface of diaphragm 2, and when this pressure has built up to move the diaphragm up sufficiently to balance spring 8, valve 16 will close again under the action of its loading spring. On reverse movement of hand wheel 11, valve 15 will be opened to exhaust the pressure fluid through conduit 36 from conduit 44 and from under diaphragm 2 until the pressure once again balances the tension in spring 8. For stability of control, there is a continual leak from conduit 44 past a leakage valve 89 and through a water-filled vessel 90. The movements of diaphragm 47 resulting from variations in the air pressure in chamber 45 actuate, through a stud 48 or a bridge member 86, valves 77, 78 similar to valves 15, 16. Valve 78 controls the supply of compressed air from a conduit 76 to a bellows-enclosed chamber 81, and through a passage 70 and a conduit 68 to bellows 56, and the resultant movement of the bellows is applied to an indicating pointer 66 and through a lever 61 and a link 62 to a rudder 64. The movement of bellows 56 is also applied to diaphragm 47 through a bridge member 53 and a spring 50 to recentre valves 77, 78. Valve 77, when actuated, controls the exhaust to atmosphere of pressure fluid from bellows 56 and chamber 81. If the space above diaphragm 2 is connected to a Pitot tube, the apparatus will constitute a ship's log.