| 摘要 |
1504836 Pressure warning devices SAFETY RESEARCH & ENG CORP 19 Feb 1976 [3 Nov 1975] 06677/76 Heading G1L [Also in Division B7] A pressure warning device comprises a spring- loaded piston 38, with a diaphragm seal 50; a passage 60 through the piston closed when the pressure on the diaphragm, applied through ports 32, is high or low and forces the piston against seats 64 or 92 respectively; and an acoustic generator 48 energized when an intermediate pressure is applied and passage 60 is not closed. The device screws on to a tyre valve which is opened by member 30. Correct tyre pressure maintains the piston against seat 64. If the pressure falls the piston unseats and an acoustic signal is generated until the pressure falls sufficiently for the piston to reach seat 92. Signals are sensed by microphones on the wheelwells, amplified, filtered and used to operate a lamp or buzzer on the vehicle dashboard. The operating circuit may include a memory device whereby the warning is given only when the operator is present. The acoustic signal is produced by an edge tone generator having a circular knife edge 76 aligned with an annular slit 88; alternatively it is produced by a Hartmann generator. To obtain warning and venting when the pressure is excessive member 66 is replaced by an apertured body 105 carrying a seal 108 and a spring-loaded piston 104. Piston 38 seals against the lower surface of piston 104 unless the pressure is excessive when piston 104 is forced up and gas escapes via passages 112, 110. The second piston may be within the first piston, Fig.5 (not shown). Thediaphragm may be flat, Fig.6 (not shown); the seal 64 may be replaced by an o-ring, Fig.8 (not shown). A filter may be inserted between the tyre and device; the acoustic generator may be covered with a blow off cap; the device may be mounted on the wheel. |
