GB421815A - Improvements in automatic reuglators - Google Patents

Abstract

421,815. Fluid - actuated valves. WINGFIELD, B. T., Brooklyn, The Green, West Drayton, Middlesex. June 1, 1933, No. 15860. [Class 135] Valves controlled by pilot or relay valves.- In an automatic regulator of the fluid pressure actuated type for controlling pressure, temperature, humidity, liquid level &c. in which a change in the controlled valve causes actuation of a pilot valve to alter the fluid pressure on a ram piston or diaphragm connected to a regulating-valve, damper &c., a flexible compensating diaphragm is connected to the pilot valve to cause movement between the pilot valve and its closing means in accordance with the fluid pressure acting on the main diaphragm. As applied to a thermostatic system, a Bourdon tube 3 is connected by a link 7 to a cranked lever 5, pivoted at 9, the arm 8 of the lever being adapted to close the pilot valve nozzle 6 which is carried by a pivoted lever 16A having an arm 17 connected to a secondary compensating diaphragm 18 mounted on a pivoted lever 19. A compensating diaphragm 20 is mounted between lever 19 and a lever arm 21 forming part of an adjusting segment 22 operated by a worm 23. A further arm 26 of this member is connected by a link 24 to an arm 25 of a member carrying the nozzle of a secondary pilot valve 14, the closing member 12 of which is connected by a link to the arm 5. The pilot valve nozzle is connected to a diaphragm 34 the pressure in which controls fluid escape from a nozzle 32 in a chamber 3 supplied from a pipe 28 through a needle valve 30. The supply 28 is also connected to a diaphragm 34 through an orifice 35A and to a reservoir 41 through an orifice 43. The reservoir is connected to the diaphragm 18 and to the nozzle 14. A lead 29 supplies fluid to the main diaphragm or other controlled device. In operation, the gearing 23 is adjusted so that the nozzle 14 is just closed by the arm 16 when the Bourdon tube 3 is in a position corresponding to the desired temperature. The setting of the device is such that at the same temperature the valve 6 would just be closed if the pressure in diaphragms 18 and 20 were half the supply pressure. If the temperature falls, air escapes from valve 6, thus deflating diaphragm 34, lowering pressure in chamber 31 and causing the main diaphragm to move so as to increase the heat supply. The temperature then increases until valve 6 closes and increases the pressure in chamber 31 and diaphragm 20, the expansion of the latter causing valve 6 to open again. The Bourdon tube thus moves until, by closing valve 6 it causes increased pressure in the chamber 31 to move the main diaphragm to a point where heat input and output balance. If the temperature stabilises above the desired point the secondary valve 14 opens through the arm 16 so that air pressure in the tank 41 and on diaphragm 18 will fall. This closes the valve 6 and increases the pressure on the main diaphragm until arm 16 is so located that escape from the valve 14 balances supply through the orifice 43. When this occurs the temperature is at the required point. The sensitivity of the apparatus may be adjusted by a needle valve 39 which reduces the pressure in the diaphragm 20.