GB667024A - Improvements relating to fluid-operated servo-mechanisms - Google Patents

Abstract

667,024. Fluid-pressure servomotor-control systems. LUCAS, Ltd., J. March 13, 1950 [March 23, 1949], No. 7888/49. Class 135. Controlling means for a fluid-pressure servomotor of the kind comprising a spring loaded piston b slidable in a cylinder a under the influence of the pressure difference between its opposite sides has a valve m adapted to set up a pressure difference in a duct j and connected at its opposite sides to the opposite ends of the cylinder a, the valve being actuated by the pressure difference across a throttle p adjusted independently of the valve m and arranged on the downstream side of the valve m. The valve m and the throttle p are arranged in a body part h formed with a chamber t containing a capsule u loaded by a spring v. The interior of the capsule is exposed to the pressure on the inlet side of the valve m whilst its exterior is connected through a passage x with the outlet of the throttle p. The closed end of the capsule is connected by a rod w to the valve m. The servomotor is adapted to control the supply of liquid fuel to a prime mover or furnace or can be adapted for analogous purposes and as shown adjusts the swash plate e of a fuel pump supplying the valve m through a passage i. A duct o connects the passage i to one end of the servocylinder; the other end of the servo-cylinder is connected to the passage j through a pipe n. The throttle p may be adjusted manually for instance by means of the rack q, pinion r and lever s. In a modification the spring v is arranged inside the capsule, and the valve m is replaced by a piston valve. Specification 629,639 is referred to. According to the Provisional Specification, the position of the throttle may be adjusted automatically in accordance with the fluid pressure in any part of the fluid system, or in accordance with the movements of a barometric device, a centrifugal governor, or a heat responsive member.