GB437231A - Improvements in or relating to expansion valves for refrigerators - Google Patents

Abstract

437,231. Expansion valves for refrigerators. BRITISH THERMOSTAT CO., Ltd., Windmill Road, Sunbury, Middlesex, and PAYNE, M., 50, Hook Road, Surbiton, Surrey. Jan. 4, 1935, No. 366. [Class 135] An expansion valve 7 for refrigerators is thermally controlled by fluid pressure acting against a static control force through the medium of a resilient metal bellows chamber 17, and the flexible walls of the chamber are utilized as an auxiliary control spring for adjusting the total static control force, an adjustable support for the fixed end 19 of the bellows being provided for adjusting the compression of the flexible walls of the bellows chamber. The valve 7 which co-operates with a seating 6 to control the amount of refrigerant entering the evaporator at 3 from an inlet 2 from the condenser, is attached to a disc 8 pressed downwardly by a spring 9. Rods 15, which slide freely in suitable guideways in the valve body 1, are fixed to the disc 8 and also to the movable wall 14 of a flexible metal bellows 12 exposed on its outer surface to the pressure in the evaporator at 3 and secured at its fixed end to a ring 13. The control bellows 17 is mounted in a housing 16 attached to the valve body 1 and sealed from the outer air to prevent " breathing. " The movable wall 18 of the bellows 17 has fixed thereto a rod 18<a> which passes through the housing 16 and bears against the wall 14, clearance being provided around the rod so that the pressures in the bellows 12 and outside the bellows 17 are equal. A flexible conduit 20 is attached to the fixed wall 19 of the bellows 17 and is connected to a sealed vessel 21 containing a volatile liquid, preferably the same as the refrigerant, and disposed in close proximity with the evaporator, the pressure changes therein caused by temperature changes being communicated to the bellows 17 and thus causing opening or closing of the valve 7. A tube 23 surrounding the connection 20 is fixed to the wall 19, and rotatable thereon is a sleeve 24 which passes through a gland 25 in the cover plate 22 of the housing 16. A cap 27 is screwed on to the plate 22 and to the outer end of the sleeve 24 and is rotated so as to adjust the compression of the flexible walls of the chamber 17. A scale 28 being provided on the cap 22 to indicate the temperature corresponding to the adjustment. Independent rotation of the sleeve 24 provides an additional adjustment intended to be carried out by an expert to set the apparatus so that it operates in accordance with the readings on the scale 28.