Patent GB-550568-A (GB)
Title: Improvements in or relating to governors for power driven mechanisms
IPC: G05D13/00
Filed: 1941-07-11
Abstract: 550,568. Fluid-pressure servomotor-control systems. KALIN, A. July 11, 1941, No. 8807. Convention date, Aug. 3, 1940. [Class 135] [Also in Group XXVI] A governor for power-driven mechanism having a hydraulic servomotor controlled by a piston control valve has the control valve and the receiving piston of a hydraulic follow-up system yieldably connected together in axial alignment and maintained in continuous undirectional rotation or are held against rotation while their respective mating elements are maintained in continuous unidirectional rotation. In the form shown in Fig. 1 the piston control valve 20 is reciprocated against the action of an adjustable loading spring 50<SP>1</SP> by weighted bell-crank levers 40 engaging shallow depressions 45a. in a flange 45 on the valve member. A ball bearing 47 is interposed between the spring abutment 51<SP>1</SP> and the control valve to permit the valve to rotate with the weighted levers. The levers have knifeedge pivots held by a cover plate 43 in hardened bearing members 41 supported in a carrier 11. The carrier 11, which is fitted with a detachable hood 52<SP>1</SP> is formed with a tubular boss 13 rotatably mounted on a tubular extension 30 of a ported seat liner for the control valve. The boss 13 carries gear teeth mating with gear teeth in a counter-shaft driven by a gear wheel engaging a gear 7 connected by a shaft 5 to the mechanism being controlled. Lubricant is supplied to the rubbing surfaces between the boss 13 and liner 30 from the servomotor system through axial and radial passages 27 in the control valve. The wheel 7 and the mating wheel on the countershaft form a gear pump for supplying motive fluid to the servomotor, the spaces between the wheels being connected through loose ball non- return valves to a passage S<SP>1</SP> leading to an oil reservoir S and through further loose ball non- return valves with a recess P<SP>1</SP>. By using four non-return valves pressure fluid is delivered to the recess P<SP>1</SP> with the wheels rotating in either direction. A passage 66 leading from the recess P<SP>1</SP> is fitted with a spring-loaded relief valve 70 leading by way of passage 72 and recess S2 back to the fluid reservoir S. The passage 66 connects with a passage leading to a pair of spring-loaded accumulators by way of a crosspassage 69. The main power piston 80 connected by a rod with the throttle or other regulating element of the mechanism being controlled has a reduced part 81 working in a bore 76 to provide a chamber P<SP>2</SP>. The chamber S4 above the part of smaller diameter is connected by a diagonal passage 92 with a space at negligible pressure, while the chamber P<SP>2</SP> is permanently connected to the recess P<SP>1</SP> so that a loading pressure constantly acts on the shoulder between the two parts of the piston. The chamber R<SP>1</SP> below the piston is connected by passages 96, 95, 94 with a recess R connected by ports 34 with the axial bore 33 in the seat liner. The bore 30 is connected by ports 36, 37 with recesses S2, S3 leading to the fluid reservoir S. The port 35 leading to the recess P<SP>1</SP> and the port 36 are normally obturated by glands 25, 26 on the control valve but when the valve is moved in one direction or the other consequent on a variation of speed the power chamber R1 is connected either to pressure or exhaust. When the valve is moved downwards pressure is admitted to the chamber R<SP>1</SP> and the piston is moved upwards to actuate the regulator in the appropriate direction. At the same time a recess 82 in the piston slides over a fixed tubular member 83 to force liquid through passages 98, 99, 101, 103 to a chamber C<SP>1</SP> where it acts on a piston 50 to compress a spring 55 anchored to both piston and control valve. The compression of the spring tends to restore the control valve to its neutral position. In order that the restoring action may fade away after an interval the passage 98 is connected to a sump S6 through a bleed passage 112 adjustably throttled by a needle 110. An adjustable stop 85 limits the upward movement of the main piston. In a modification the power piston is spring loaded while the control valve is held against rotation and its tubular seat rotated.