Patent GB-976505-A (GB)
Title: Improvements in or relating to temperature-responsive actuators
Inventor: BARRATT AUBREY
IPC: G05D23/12
Filed: 1960-03-25
Abstract: 976,505. Valves. S. SMITH & SONS (ENGLAND) Ltd. March 27, 1961 [March 25, 1960], No. 10607/61. Heading F2V. [Also in Division G1] A temperature-responsive actuator required to produce a relatively large movement over a limited, fixed, temperature range comprises a closed housing having a rigid part and an extensible part in communication with each other. The extensible part is provided with an anchorage which upon extension moves linearly in relation to the rigid part. The rigid part may therefore be fixed and a member to be actuated secured to the anchorage, or alternatively, the anchorage may be fixed and a member to be actuated secured to the rigid part. A portion of the rigid part is filled by a substance, e.g. wax, which changes its state from solid to liquid over the said temperature range with a substantial increase of volume, and the remainder of the housing is completely filled with a liquid whose boiling point is substantially above the said range. In one embodiment shown in Fig. 1, a rigid part 1 of a closed housing is secured to the extensible part, a bellows 8, at the upper end of the bellows and communication is through a hole 7. The upper portion of the rigid part 1 contains a wax 25 and the remainder of the closed housing is filled with ethylene glycol 26. The lower end of the bellows 8 is sealed into a dished portion 9 of a circular plate 10 which is termed the anchorage above. In this embodiment, the rigid part 1 carries the member to be actuated in the form of a valve member 21 attached by a stud 20. The valve seating 16 is rigidly attached by straps 13 and 14 to the circular plate 10. With a temperature increase the wax 25 expands downwardly into the portion 6 of the rigid part 1, so forcing the ethylene glycol 26 through the hole 7 to expand the bellows 8. This in turn forces the rigid part 1 upwards so opening the valve member 21. Figs. 3 and 4 (not shown) are schematic cross-sectional views of two modifications of the temperature actuated valve described above. In both embodiments the rigid part of the housing takes the form of a hollow annular chamber, into which fits a bellows in communication with said chamber. The free end of the bellows carries a valve member similar to that described above. The bellows of Fig. 3 is made from metal and that of Fig. 4 is made of reinforced rubber. A quantity of wax is contained in the annular chamber and the remainder of the housing, including the bellows, is filled with ethylene glycol. In Figs. 5 and 6 (not shown) a further embodiment of a valve is illustrated in which the rigid part of a housing is generally cylindrical in shape, and is secured to the valve seating of a valve member to be actuated. The valve member is anchored to the free end of a bellows in communication with and attached to the said rigid part. A quantity of wax is contained in the rigid part and the remainder of the housing is filled with a liquid such as ethylene glycol. In all the embodiments, the extensible part of the housing is resiliently restrained towards an extended position so that the extensive part tends to be extended if the housing develops a leak.