GB585683A - Improvements in and relating to indicating, recording and controlling apparatus - Google Patents

Abstract

585,683. Fluid-pressure servomotorcontrol systems. GREGORY, C. H., HALL, J., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. March 7, 1944, No. 4194. [Class 135] [Also in Group XIX] Relates to apparatus for indicating, recording or controlling small movements and physical quantities such as temperature and pressure, which are capable of producing small movements, the apparatus being of the kind in which the small movements actuate a regulating- valve in a fluid-pressure system, the pressure of which gives the required indication or control. According to the invention, the said fluid pressure is regulated by a ball valve 17 co-operating with a horizontally arranged seating 18 and adapted to be pressed by the fluid pressure into contact with an abutment 16 which is movable to and from the seating by the said small movements. These movements are transmitted to. the abutment by a lever 8 having a flexible strip 15 for fulcrum at one end, and at the other end a light spring 21 attached to a U-spring 22 and fitted with a tension-adjusting knob 24. Pipes 5, 6 are provided for applying pressures to two metallic bellows 1a, 1, the difference between these pressures being the pressure whose indication is required, and these bellows, are connected by straps to the lever 8. A further bellows 4 connected also by a strap to the lever 8 is subjected to pressure which is supplied through a reducing-valve 11 to the system including, the ball valve 17 and the pressure-indicating instrument 13, which indicates 'any change in the pressure difference between the pipes 5, 6. The member transmitting movements to the abutment 16 may be made of phosphor bronze or the material known under the Registered Trade Mark " Invar." A modification is described in which the pipes 5, 6 communicate with the exterior and interior respectively of a bellows. Examples of applications of the invention comprise indicating or controlling the following fluid pressures including very low absolute pressures.; the flow of fluids in pipes by using the apparatus in conjunction with a venturi or pitot tube &c. ; temperature by use in conjunction with a gas thermometer; density of liquids and gases ; liquid level by use with an air-operated gauge.