GB878411A - Squeeze-push temperature-or pressure-responsive element - Google Patents

Abstract

878,411. Temperature - resposive actuating-elements. Jan. 9, 1958, No. 900/58. Class 64(2) [Also in Group XXIX] In an actuating-element, the thermal expansion of material such as paraffin wax or para-dichlorbenzene 42 forces out a pin 26 from the position shown in Fig. 3 to the position shown in Fig. 4, first by squeezing a sock portion 36 of a rubber body surrounding the pin and then, when the bottom 46 of the pin has reached the level of a flange 34, by upward pressure on the lower surface of a portion of the rubber body forming an annular plug 32 in an upper cup 14 of the casing of the element, the upward pressure being ejected through the inner part of a flange 34 between the sock 36 and the plug 32. The casing is formed by two cups 14, 16 held mouth-tomouth by a ring 20 with the rubber flange 34 clamped between them. Apart from its mouth and the hole accommodating the pin 26, the cup 14 may be unapertured, Figs. 1, 2 (not shown) or there may be holes 50, .03 inches in diameter, to take up some of the rubber of the body 32, 36, as shown in Fig. 4, on over-expansion of the material 42. when the pin 26 is fully extended. The pin is returned to the Fig. 3 position by spring. The rubber body may be formed with the plug 32 separate from the sock 36 and flange 34, Fig. 5 (not shown). For the expulsion of any trapped ambient medium, the top cup 14 may be of sintered metal powder so that pores are provided or there may be at least one passage through the wall of the cup. The top wall 24 of the cup 14 may be thin, Fig. 7 (not shown). To increase sealing pressure, the top of the plug 32 may diverge upwardly and still be enclosed by the top wall 24, Fig. 8 (not shown), or it may extend through the top of the cup 14 as in Fig. 9. Instead of having a diverging upper part ,the plug 32 may terminate in a cylindrical part, Fig. 10 (not shown) and in that embodiment a synthetic resin washer encircles the pin above the plug, to retain the rubber. In another embodiment, Fig. 11 (not shown), the plug 32 is cylindrical.