GB1452324A - Electrical switches - Google Patents

Abstract

1452324 Snap-action switches; tetractive switches; fluid actuation of switches; switch cases POST OFFICE 13 Aug 1974 [14 Aug 1973] 38468/73 Heading H1N A switch has a flexible resilient curved element 12 operatively associated with a pair of contacts 18, 22 so that contacts 18, 22 are closed when element 12 is convex in one direction and open when element 12 is convex in the opposite direction, operating means 26, 16 to move over element 12, and a housing 10 with portions 14 supporting element 12 and which is resiliently deformable at least in part to permit resilient movement of support portions 14 during movement of element 12. As shown, depression of button 26 deforms housing 10 and depresses rigid projection 16 and contact 18 on projection 16 which depresses contact 22 on element 12 causing element 12 to snap over to engage contact 20 on projection 16. When pressure on button 26 is removed, the resilience of housing 10 pulls back projection 16 causing element 12 to snap back. Element 12 is of electrically conductive material. In a second embodiment, Fig. 5 (not shown) in place of contact 20 is a ledge (40) and the housing is formed with corrugations (42) to give it some resilience. In a third embodiment, Fig. 6, coverplate 50, projection 54, rear portion 56 and arm 68 are relatively rigid with a resiliently deformable port 58 inter-connecting plate 50 and portion 56. Curved element 60 lies between shoulders 62, 64 on projection 54, element 60 being electrically conductive and forming one contact of the pair, the other contact 66 being on shoulder 64. If arm 68 is moved downwards, portion 56 pivots about the resilient part, element 60 engages shoulder 62 and is snapped over engaging contact 66. To break contact, arm 68 is moved upwards and shoulder 64 snaps element 60 back. In a fourth embodiment, Fig. 7 (not shown), suitable for operation by fluid-pressure, the end-walls (72) are relatively stiff and side walls (74) flexible, depression of a wall 74 snapping over curved element (78) between shoulder (82) and contact (80) on rigid projection (76). In a fifth embodiment, Fig. 8 (not shown) the projection (92) extends the length of the resiliently deformable housing (84), there is a pushbutton (86, 88) at both ends, curved element (94) is at an angle across the inside of housing (84) and element (94) is snapped away from fixed contact 96 to engage a shoulder (98) by depression of button (86) and remains in that position until the opposite button 88 is pressed to snap it back. Due to element (94) being inclined relative to the line of movement of contact (96) the latter wipes element (94) to clean the contact surfaces. In a sixth embodiment, Fig. 9, housing 102 is of resiliently deformable plastics material and there are two curved elements 104, 106 integral with housing 102. There is a link 108 connecting elements 104, 106 so that depression of button 116 depresses dog 114 which snaps over element 104 to press contact spring 120 against contact 118 and link 108 simultaneously snaps over element 104. The switch remains in this position until button 116 is again depressed which causes dog 114 to engage element 106 which snaps it over, link 108 pulling back element 104 so that contacts 118, 120 can separate.