GB1217812A - A differential pressure responsive switch - Google Patents

Abstract

1,217,812. Fluid actuation of switches. F. W. DWYER MFG. CO. Inc. 30 May, 1969 [7 June, 1968], No. 27469/69. Heading H1N. [Also in Division G1] A differential pressure sensitive switch comprises a flexible diaphragm 19 clamped by its rim between base 1 and housing 25, low and high pressure inlets 3, 5, on the same side of the diaphragm 19, and one or more communicating passageways 31 in the diaphragm rim between annular grooves 15, 43 in the diaphragm clamping surfaces of the base 1 and housing 25, groove 15 communicating via a passage 13 with the high pressure inlet 5 so that high pressure is applied to the opposite side of the diaphragm from the inlets 3, 5. Four spaced recesses 49 connect groove 43 with the high pressure space between the diaphragm 19 and housing 25, see also Fig. 9 (not shown). A diaphragm plate 39 has a protuberance 99 engaging the long arm 69 of a bell-crank lever 65, movement of the diaphragm causing arm 69 to move an actuating lever 84 to actuate a microswitch 23. An adjustable spring 9 is fastened to the short arm 67 of lever 65 and is secured to an adjusting nut 61 at its other end. Movement of an adjusting screw 11 causes nut 61 to move axially, without turning, in a recess 7 of base 1 to adjust the pressure of coil spring 9. The base 1 may be transparent and have a scale along which nut 61 visibly moves, Fig. 2 (not shown). There may also be a visible switch position indicator 100, Fig. 2 (not shown). An enclosure 101 for the leads to switch 23 has four tabs 103 fitting on four studs 105 of base 1 and has a removable lid 109. A mounting bracket 113 is mounted on two of the studs 105. Nuts 115 hold the enclosure 101 and bracket 113 on the studs 105. The diaphragm 19 has projections 37, on which the diaphragm plate 39 locates, and has an annular rib 33 and a series of radial strengthening ribs 35, Fig. 11 (not shown). The thin convoluted annular portion 41 allows easy flexing under pressure of the diaphragm, which may be of neoprene. Base 1 and housing 25 may be of metal or plastics.