GB762825A - Improved pressure-responsive apparatus - Google Patents

Abstract

762,825. Gas turbine plant. GENERAL MOTORS CORPORATION. Oct. 22, 1954, No. 30469/54. Class 110 (3). [Also in Group XXIX] A gas pressure responsive device includes a bellows acting through a pair of lever arms, one of which is adjustable, and a cam wherebymovement of a controlled member may be effected in response to a desired, e.g. logarithmic, function of pressure. In an embodiment, applied to control of the fuel supply to a gas turbine engine in accordance with compressor inlet and delivery pressures, the inlet pressure acts on the exterior of a bellows 125 (Fig. 15) which has a connection 134 with a lever 57<SP>1</SP> mounted on a spindle 61<SP>1</SP> which carries a lever 141<SP>1</SP> (Fig. 18) connected with a control valve 144 for a servo piston 160. The bellows 125 is evacuated and spring loaded internally. Movement of the valve 144 causes a corresponding movement of the servo piston due to movement by the piston of a ported sleeve 153 with which the valve 144 coacts. The sleeve 153 carries at its end a roller 175 coacting with a cam lever 177 pivoted on a spindle 178 and having an adjustable abutment 183 with a spring-loaded lever 180 also pivoted on the spindle 178 and engaging at its lower end a rod 188. The cam surface 176 of the lever 177 is shaped so as to provide the required relation between pressure and movement of the member 188. Compressor delivery pressure acts through a connection 108 (Fig. 4) on a diaphragm 101 which actuates a valve 90 controlling the pressure of oil in a cylinder 54 containing a piston 53 which is connected to an evacuated bellows 42 loaded by springs 47, 49. The pressure in the cylinder 54 reacts through ports 70a on the diaphragm 101 so that the pressure in the cylinder and consequently the position of the piston 53 are related to the compressor delivery pressure, the bellows 42 being of the same area as the piston 53 so as to eliminate the effects of variations of ambient air pressure. The piston 53 is also connected to a lever 57 mounted on a shaft (not shown) which carries a lever similar to the lever 141<SP>1</SP> and which actuates a control valve and servo piston operating an output member through a cam lever and roller assembly similar to that shown in Fig. 18. The two servo pistons 160 are mounted side by side in a common housing and the two output members may be parts of a device whose functioning is to be made dependent upon the compressor inlet and discharge pressures.