GB680949A - Improvements in and relating to bellows operated devices - Google Patents

Abstract

680,949. Temperature-responsive actuating-elements. BRITISH THOMSON-HOUSTON CO., Ltd. July 19, 1950 [July 29, 1949], No. 18033/50. Class 64 (ii) [Also in Groups XIX and XXII] Variations in operation of a temperature-responsive device operated by a bellows are minimised by limiting the extension of the bellows to that permitted during subsequent operation and applying pressure exceeding the maximum to be encountered in use and subsequently calibrating the bellows. A bellowsoperated device for minimising variations in operation of refrigerating apparatus described in Specification 649,373 controls a valve element 16 which in turn controls the flow of liquid refrigerant. The valve housing 8 is in two parts 9, 10 the lower part 10 forming a chamber 11 in which the element 16 is placed, while the bellows 19 is in the upper part 9. From the chamber 11 conduits 12, 13 (not shown) lead to the evaporating portion 5 (not shown) of the system and conduits 14, 15 lead to the condensing portion 4 as in Specification 649,373. Internally the bellows is subjected to the pressure in the evaporating portion since it is open to the chamber 11. As the temperature of the evaporating portion rises the pressure within the bellows increases and the bellows tends to expand against the influence of a spring 20. As the bellows expands the valve element 16 is moved from its seat by a spring 21 to allow refrigerant to flow into the evaporating portion. Reduction in pressure reduces or stops the flow of refrigerant. The spring 20 is placed between two elements 22, 23. The compression of the spring and hence the setting of the valve is controlled by a cam 24 operated by a handle secured to a projection 25. Movement of the cam is transmitted to the element 22 through an elongated member 26. The upper part of the housing 9 has a stepped portion 27 arresting the upward movement of the cup-shaped element 23 by engagement with a flange 28 of the element. The valve is set prior to use by applying a pressure to the interior of the bellows which is in excess of the pressure for the maximum temperature conditions to be expected during shipment or storage. Before inserting the valve in the refrigerating system, the valve is placed with the open ends of the conduits 12, 13, 14, 15 in contact with a pad 30 of compressible material, e.g. rubber, the valve and pad being supported in a clamp 31 having a forked arm 34 engaging the shoulder 27 of the valve housing. By forcing the end 37 of this arm upwardly, the valve is pressed downwards, while pressure is applied to the chamber 11 by coupling a conduit 38 to a source of compressed air. The pressure is maintained for about 1 min., after which the coupling 40 is disconnected and the valve removed from the clamp. The valve is then placed in an oven for about 1¢ hrs. at 155‹C. to partially relieve the stresses in the bellows, after which the element 26 is inserted. The coupling 40 is used for charging refrigerant to the system when the valve is in position. Specification 388,514, [Group XIX], also is referred to.