GB904122A - Improvements in servomotor control apparatus - Google Patents

Abstract

904,122. Fluid-pressure servomotor-control systems. SULZER FRERES S.A. Feb. 6, 1959 [Feb. 17, 1958], No. 4319/59. Class 135. Pressure signals responsive to fluid flow are transmitted by a valve 3, a relay 100 and a change-over valve 5, when the latter is in the position A shown, to a spring-loaded servomotor piston 6 controlling a throttle valve 70 in the flow line. The valve 5 also feeds these signals to one side of a spring-loaded piston 250 of a comparator 25, the other side of which piston is subject to a signal from a manual device 80 transmitted via a relay 120 and the valve 5; inequality in these signals translates the piston 250 and hence a slide valve 26 to direct fluid to and cause movement of a piston 180 to increase the spring-loading of the relay 120 until the signal transmitted by the latter is equal to that from relay 100. With the valve 5 in the position B the loading imposed by the piston 180 is slowly removed in a time dependent upon the setting of a throttle 34 across the piston whereupon the servomotor 6 is responsive to the manual device 80. The relay 100 is also provided with a comparator 27, slide valve 30 and piston 31 whereby its loading spring 33 is adjusted when the throttle valve 70 is controlled by the manual device 80 should the signals on either side of the piston of the comparator 27 be unequal. The piston 31 is connected to the spring 33 by a self-locking slide 32 and any loading imposed upon the spring 33 by the comparator 27 is immediately available for controlling the servomotor 6 as also are the flow-responsive signals when the valve is returned to the position A. In a modification, the equalization of either signal is effected by one set of apparatus, the change-over of the connections of which is done upon operating the valve 5. The manual signal may be replaced by an automatic one from another system. The regulating apparatus may be used to maintain constant the internal temperature of a building irrespective of the ambient conditions. The apparatus may be applied to mechanical, electrical or electro-mechanical systems and signal equalization need only be effected when the valve 5 is operated. The response of the valve 3 may have a linear or quadratic relationship with the measured value of the signal.