GB536242A - Improvements in governing mechanisms - Google Patents

Abstract

536,242. Fluid pressure servomotor-control systems. BRITISH THOMSON-HOUSTON CO., Ltd. (General Electric Co., Ltd.). Dec. 7, 1939, No. 31674. [Class 135] A governing-mechanism has a controlled element actuated by two hydraulic power devices, one of which has a delayed action, both devices being controlled by a single control valve actuated by the controlling impulse. Fig. 2, shows the invention applied to the control of a turbine supply valve in accordance with the pressure in the turbine exhaust. The turbine supply valve is operated by a doubleacting piston with piston valve and floating- lever follow-up control. The piston valve is actuated by a rod 15 loaded by a spring 56 and provided with a pointed end engaging a recessed block 54 mounted on the rigid end wall 53 of a bellows 49. The bellows is secured to a short flanged cylinder 50 clamped to the casing 21 by a cover 51 and bolts 52. Pressure fluid is supplied to the chamber surrounding the bellows by a pipe 64 fitted with a restriction 65 and the pressure is varied by a leak-off valve 38, the exhaust fluid passing by way of passages 66 and chamber 68 bolted to the casing to a discharge pipe 67. A block 45 supported by arms 44 and spring arms 42 or a diaphragm has a hemi-spherical part engaging a similar recess on the back of the valve and has a recessed seat adapted to receive the pointed end of an adjustable strut 37. The other end of this strut engages a recessed block 36 in a lever 33 mounted on a pivot 34. A bellows 27 secured to a fitting 25 is subject to the turbine exhaust pressure admitted through a pipe 14 and is connected to the lever by a strut 31. The lever is loaded by a spring 84 adjusted by a screwed spindle rotatably mounted in the casing and co-operating with a movable abutment 85 guided by pins 87 and by two other springs 59 82 acting on opposite ends of the lever. The spring 59 has an intermediate convolution secured to a screwed part of the rod 15 by a clamp 61 while the spring 82 is similarly connected to a rod 80 adapted to be actuated by a bellows 71 similar to the bellows 49. The chamber surrounding this bellows is connected by a passage 73 fitted with a throttle 74 to the passage 39 controlled by the valve 38. With an increase of pressure in the pipe 14 the valve is moved towards its closed position to increase the pressure on the bellows 49 and initiate the closing of the turbine valve. At the same time pressure slowly builds up beneath the bellows 71 to give an increased movement to the valve 38.