Patent GB-1020261-A (GB)
Title: Fluid-pressure-operated control apparatus
IPC: F15B11/10
Filed: 1962-10-22
Abstract: 1,020,261. Fluid pressure control systems. ROBERTSHAW CONTROLS CO. Nov. 26,1962 [Nov. 24,1961; April 26, 1962], No. 44652/62. Heading G3P. A vacuum-energized control system comprises a master unit 12, Fig. 1, (not shown), connected at 62 to a vacuum source 16 and a slave unit 14 operating a member 46 and connected by a conduit 32 with the master unit. A diaphragm 36 in the slave unit, connected to the member 46 and loaded by a spring 38, takes up a position dependent upon the degree of vacuum in a chamber 30. The spring load may be varied by an adjustable, external spring 58. The master unit comprises a diaphragm 76 subject on its lower surface to atmospheric pressure and coacting on its upper surface with a tube 60 communicating through a passage 64 with the vacuum source. Also coacting with the upper surface of the diaphragm is a spring-pressed disc 84 overlying an orifice 90 in the diaphragm. Withdrawal of the tube 60 from engagement with the diaphragm, by rotation of a screwed carrier, results in an increasing vacuum in the chambers 28 and 30 until the diaphragm 76 re-engages the tube 60, whilst downward movement of the tube 60 lifts the centre part of the diaphragm 76 away from the disc 84 to allow atmospheric air to pass through the aperture 90 and reduce the degree of vacuum until the diaphragm 76 has been depressed sufficiently to cause closure of the aperture 90. Adjustment of the tube 60 may be effected by temperature responsive means, and a number of master and slave unit combinations may be connected through a programme controller with the vacuum source so that they are brought into operation in a desired sequence and for a desired period of time. A single master unit may control a number of slave units. Fig. 11 illustrates a modified master unit in which a bowed spider 48<SP>1</SP>, of a material having a lower coefficient of thermal expansion than its housing 12<SP>1</SP>, causes variation of vacuum in a chamber 18<SP>1</SP> in response to temperature changes. The slave unit in this case may control hot or cold air dampers or heating or cooling apparatus for the space, e.g. a room, in which the master unit is situated. The spider 48<SP>1</SP> acts through an adjustable screw 62<SP>1</SP> on an apertured member 44<SP>1</SP> engaging a diaphragm 20<SP>1</SP> which coacts with a fixed tube 36<SP>1</SP> communicating with a vacuum source and is formed with an orifice 22<SP>1</SP> normally closed by a spring- pressed disc 24<SP>1</SP>. Leftward movement of the member 44<SP>1</SP> in response to increase of temperature results in opening of the orifice 22<SP>1</SP> so that atmospheric air can pass into the chamber 18<SP>1</SP> from apertures 46<SP>1</SP> in the member 44<SP>1</SP> and an opening 92<SP>1</SP>, and the resulting increase of pressure in the chamber 18<SP>1</SP>, which passes through a conduit 66 to the slave unit, reacts on the diaphragm to close the aperture 22<SP>1</SP>. Decrease of temperature causes the diaphragm to move away from the end of the tibe 36<SP>1</SP> to increase the vacuum in the chamber 18<SP>1</SP>. Adjustment of the controlled temperature is effected by rotation of the housing 12<SP>1</SP> which has screw-threaded engagement with a member 14<SP>1</SP>.