Patent GB-581140-A (GB)
Title: Improvements in or relating to liquid control apparatus
IPC: F15B21/00
Filed: 1942-11-12
Abstract: 581,140. Centrifugal governors. PUGH, C. A., BOOTH, D. G., and PLESSEY CO., Ltd. Nov. 12, 1942, Nos. 16022/42 and 18715/43. Addition to 577,311, [Group XXIX]. [Class 57] [Also in Group XXIX] A liquid control apparatus as claimed in the parent Specification [see Group XXIX], is provided with means for the automatic relative adjustment of the leaks by controlling one of them by a speed responsive hydraulically loaded governor. In the arrangement shown in Fig. 5 a differential bye-pass valve 2a interposed between a low pressure conduit 3 and a conduit 1 supplying fluid from a high pressure source to an engine is controlled by varying the pressure in a control chamber 8 connected through a pipe fitted with a restriction 19 to the conduit 3 and through a governor-controlled valve 7 with the conduit 1. The actuating piston 41 may be lightly loaded by a spring 48 and a buffer spring 49 may be interposed between the piston and the valve 2a. The valve 7, which is pressure balanced, is formed integrally with a movable hydraulic loading cylinder 10 acted on by centrifugal weights 13 mounted on a carrier 13a on a rotating shaft 13b. Fluid is supplied to the space 120 inside the loading cylinder from the conduit 1 through pipes 4, 25, constant flow valve 23, pipes 27, 28, 32, restriction 31 and pipe 35. The constant flow valve comprises a pressure balanced lift valve loaded by a spring 30 and actuated by a diaphragm 26 subject to the pressures on the two sides of the restriction 31. The pressure in the space 120 is regulated by an adjustably loaded relief valve. This valve comprises a valve member 34a mounted on a control rod 38 and co-operating with a seat movable by fluid pressure against the action of a loading spring 37. Fluid discharged through the relief valve passes to the conduit 3 by way of pipe 39, governor casing 12 and pipe 45. A minimum pressure valve 40 is provided to connect the control chamber 8 to the pipe 28 in the event of the pressure in the control chamber falling below the value required to maintain the high pressure line at a value which will give a constant flow through the loading system. In a modified arrangement, the control chamber is connected to the conduit 1 through a restriction and the governor valve controls the connection with the conduit 3. In the arrangement shown in Fig. 6, the valve 33 is replaced by two similar valves one 51 adapted to control the speed of the engine from starting up to idling speed the other 50 controlling the engine from idling up to maximum speed. After starting, the valve 51 is isolated from the loading control conduit 35 by a valve 60 opened against the action of a spring 62 by a solenoid 82. The loading springs of the valves 50, 51 are adjusted by cams 68, 72 selectively clutched to a constantly running electric motor whose speed is. regulated by a field rheostat adjusted by a barometric capsule 67. When it is desired to start the engine, a lever 78 is moved into the idling position this removes a stop 86 from a clutch 89 to permit the motor acting through worm gearing 64 and toothed gearing 70 to rotate the cam 68 to the idling position. Depressing a push-button switch 80 energizes a holding switch 84, the solenoid 82 to open the isolating valve, and a solenoid 83 to engage a clutch 73. This permits the electric motor acting through worm gearing 71 and toothed gearing 74 to rotate the cam 72. When the loading adjustment has slightly passed the idling speed a tappet 85 on a rack actuated by a pinion 76 on the cam shaft opens a switch 86<1> to break the solenoid circuit and allow spring 87 to return cam 72 to its initial position. In the event of the motor 65 failing the hand lever 78 may be coupled by a catch device 123 to the driven side of the clutch to permit direct manual control of the engine speed. The switch 84 may also operate a starter motor relay and the tappet 85 may switch the ignition on and off at the desired point. The electric motor may be arranged to be inoperative when not required to drive the control. In another form (Fig. 8, not shown) the cam adjusting the relief valve loading is moved to the minimum speed position by a hand-operated tappet engaging a second tappet on a gear segment engaging a pinion on the cam shaft. Rotation of the shaft also winds up a spiral spring which, when the control lever is moved to increase the speed, rotates the cam shaft at a speed determined by a brake controlled by a centrifugal governor connected to the cam shaft by worm, ratchet and space gearing. In a modification (Fig. 9, not shown), the restriction 31' is inserted on the inlet in place of the outlet side of the constant flow valve and the minimum pressure valve controls the connection between the high pressure conduit and the main control chamber. In a further modification (Fig. 10, not shown), an adjustably spring-loaded diaphragm actuated differential pressure regulator replaces the constant flow and relief valves. According to the first Provisional Specification, the control chamber is connected to the high pressure through the medium of a piston-actuated flow limiting valvewhich between certain limits acts as a constant flow for supplying the hydraulic loading system. Further to limit acceleration a control valve may be arranged in parallel with the primary control valve and actuated by an inertia governor driven from the engine. The inertia governor may comprise a lever locking about a fixed pivot and extending from a carrier in which are supported two planet gears differing in diameter and meshing with two other gears of a differential gear rotatable with the engine shaft. Alternatively this may be effected by fitting a delay action device such as a centrifugal friction brake to the manual speed control. In another form the relief valve adjusting rod is fitted with a piston subject to the pressure in the hydraulic loading cylinder and on the other side is connected through a fixed or adjustable throttle with the low pressure conduit. To lower speed the piston is moved positively by a manually controlled rod. But when the rod is moved in the opposite direction to increase speed fluid pressure causes the piston to follow the rod at a rate determined by a friction device such as a centrifugal friction. brake.