Pressure sensing switch for pneumatic tyre - has diaphragm moving switch contacts if pressure falls, to initiate oPeration of warning signal generator

摘要

The pressure detector includes a plastics cylinder (103) containing compressed gas which is introduced through a small hole (116) during manufacture. The hole is then filled with suitable cement. The opposite end of the cylinder is closed with an impermeable membrane (105) of rubber or silicon attached by a ring (104) with screws (115). A cross (104a) formed across the centre of the ring prevents excessive flexing of the membrane. A lever (106) pivoting about an axis (111) resting against the membrane controls the relative movement of the contact surfaces (109,110). The circuit including the contacts is normally closed, the pressure in the tyre being sufficient to press the membrane inwards. If however the tyre pressure falls below an acceptable level, the diaphragm moves outwards and the contacts separate operating a warning signal generator.