Patent GB-588252-A (GB)
Title: Improvement in fluid pressure control systems
IPC: F02D25/02
Filed: 1944-07-26
Abstract: 588,252. Fluid-pressure servomotor-control systems. BENDIX-WESTINGHOUSE AUTOMOTIVE AIR BRAKE CO. July 26, 1944, No. 14287. Convention date, July 28, 1943. [Class 135] In a control system for two engines or two groups of engines, particularly for the engines of an aircraft, a single manual control element is provided by means of which the engines or groups of engines may be controlled concurrently in synchronism or selectively. As shown, two engines 6, 7 have their throttles actuated by servomotors 16, 17 supplied with pressure fluid from a reservoir 24 through governor control valves 30, 31 and a manually operable control valve 36. The valves 30, 31 which are similar are operated by governor weights 65 driven from the respective engines which in the case of valve 30 actuates an inlet and exhaust valve member 51, 53 to supply pressure fluid from conduit 27 to conduit 28 and servomotor 16, or, exhaust from conduit 28 through a bore 59 and a port 60 to a chamber 47 open to atmosphere through an outlet 48. Fluid-pressure loading is applied to the governor to adjust the engine speed by means of a chamber 49 having a diaphragm 55 to which pressure fluid is supplied through a conduit 38 under control of the valve 36, this pressure acting in opposition to the centrifugal effect of the governor to provide a balance at the desired speed. The valve 31 controls the engine 7 in a similar way and is also controlled by the valve 36 supplying pressure fluid through conduit 39. The control valve 36 shown in detail in Fig. 2 consists of an inlet and exhaust valve 79, 81 of the self-lapping type which regulates the pressure from an inlet 74 to outlets 102 and 103 to which are connected the conduits 39 and 38 leading to the governor valves 31 and 30 respectively. The pressure is adjusted by the loading of a spring 101 by means of a cam 99 on moving a control lever 97 in a plane perpendicular to the plane of the drawing. This loading acts upon a diaphragm 89 having a valve-operating member 83 secured to it which operates the valve member 79, 81. The regulated pressure in an intermediate outlet' chamber 75 acts upon the diaphragm 89 through a passage 88 and the member 83 has an exhaust passage 86 through it communicating with an exhaust chamber 77. The pressure fluid from the chamber 75 to the outlets 102 and 103 is further controlled by inlet and exhaust valves 108, 110 and 125, 126 respectively which are operated by plungers 112, 132 under control of a sliding cam member 118 having cam surfaces 123, 139 which is actuated by movement of the lever 97 in the plane of the drawing. Thus, one or other of the valves 108, 125 can be closed to cut off the supply of pressure fluid to one of the governors 30, 31 to reduce the speed of the respective engine to idling whilst maintaining the speed and control of the other engine, the lever 97 being pivoted in two planes at 92 and 98 to allow both directions of movement and control. Pressure indicators 40, 41 are provided for the servomotors 16, 17 and under normal conditions of synchronous operation these should show the same pressure. If the efficiency of one engine should fall off at all, this will be indicated by a higher pressure required in the servomotor to provide a greater throttle opening to maintain the synchronous speed. Instead of single engines, groups of engines may be controlled in substantially the same manner.