GB1459607A - Undulating pressure responsive devices - Google Patents

Abstract

1459607 Pressure gauges; liquid level indication R E NELSON 10 Sept 1974 [10 Sept 1973] 39476/74 Headings G1H and G1L In one embodiment of an undulating fluid pressure responsive device an undulating pressure such as is produced in a probe 96 in oil in an engine or compressor crank-case 91 is applied to a nipple 45 and oscillates a diaphragm 40 to produce a corresponding pressure variation in a space 39 to open a valve 30 and draw air into a space 39. When the valve 30 is closed on the return stroke, the air in space 39 is compressed and forced through passages 38, 37 and 37a to a region 35 to open a valve 32 to admit air to a space 59 and lift a diaphragm 56 to allow air, in normal conditions, to flow through a restricted passage between an opening 66 and a poppet valve stem 68 to a region 67 and then through ports 79 to atmosphere. If the undulations are too strong, as occurs when the oil level falls below the level of a port 95 in the probe end, and accumulated air cannot escape rapidly enough, the face 71 of a member 62 carried by the diaphragm 56 rises far enough to move a head 69 of the poppet valve into engagement with a button 72 to activate a switch 73 e.g. to shut down the engine. In another embodiment, Fig. 3 (not shown), pulses reciprocate a diaphragm (141) similar to 40, as before, which in this case withdraws air from a capsule formed by rigid and flexible cup-like members (178, 180) joined mouth to mouth and having an air bleed (200) to prevent low-pressure developing under normal conditions. When strong pulses develop, however, due e.g. to a low oil level, the flexible cup collapses and operates through linkage a shut-down device or an oil level make-up valve Fig. 4 (not shown).