GB962107A - Improvements in or relating to governor-controlled hydraulic systems - Google Patents

Abstract

962,107. Fluid-pressure servomotor control systems. PLESSEY CO. Ltd. Nov. 11, 1960 [Nov. 11, 1959; Nov. 20, 1959], Nos. 38322/59 and 39468/59. Heading G3P. A governor-controlled hydraulic system wherein a positive-displacement pump 2, Fig. 1, driven at substantially constant speed supplies liquid to a circuit which includes one branch 4 leading to the pump inlet or to some other low pressure point through a metering aperture 6 and a second branch also leading to the low pressure point which contains second metering aperture 13 in series with a variable aperture has the variable aperture controlled by a centrifugal element 6. 7 driven by a shaft 1 whose speed is to be kept constant, a differential piston 11 constituting the servomotor being subject on its smaller-area side to the pressure between the pump and the aperture 6 and on its larger-area side to the pressure between the variable aperture and the aperture 13. The shaft 1 is coupled to the pump 2 and to a shaft 3 having a bore 8 supplied through a chamber 17 from the pump and obturated by the element 6. When the latter begins to uncover the bore 8 pressure rises in chambers 9, 10 to move the piston 11 to the right and reduce the speed of the shaft 1 through a constant-speed drive, such as that described in Specification 952,982. In Fig. 2, a gear pump 21 supplies one side of the piston 33 through a reed type governor 29 and a relief valve 30 for keeping the pressure constant while the other side of the piston is supplied through a duct containing an adjustable bleed valve 28. Actuation of the governor in response to speed changes causes pressure variations on the right hand side of the piston 33 to adjust the speed control.