GB483863A - Improvements in speed governors for power engines - Google Patents

Abstract

483,863. Fluid-pressure servomotorcontrol systems. FAGELUND, R. Dec. 23, 1936, No. 35267. [Class 135] A fluid-pressureactuated piston 13 for adjusting the throttle valve 3 of an engine is acted upon by pressure fluid, for example steam, through ports 16 and 21 under control of a slide valve (not shown), operated by a governor of the type described for example in Specification 273,927, [Class 57], to actuate the valve 3 through a rod 6 which is connected at 15 to the piston rod 14. Whilst the fluid pressure acts on the full area of the piston 13 to move the throttle valve 3 in the opening direction, the closing movement is effected by the pressure fluid acting upon the annular area 22 so that the closing force is not as great as the opening force. An auxiliary valve member 23 moves with the piston 13 under the action of a spring 29 to close the passages 18 for the admission of pressure fluid to the top side of the piston 13 when the piston has made only part of its stroke, the remaining portion of the stroke being effected by the expansion of the pressure fluid so that the opening movement is effected with gradually decreasing power to prevent shock. The closing movement may also operate in a similar way by providing a pressure-communicating port 33 to the lower side of the piston controlled by a groove 32 in the rod 14 so that the pressure-fluid supply is cut off after a short closing movement, the remaining movement being effected by expansion. The closing movement may be effected by a spring instead of fluid pressure.