| 摘要 |
1505970 Indicating low pressure in pneumatic tyres GENERAL MOTORS CORP 18 Oct 1976 [12 Nov 1975] 43157/76 Heading B7C A pneumatic tyre low pressure warning system comprises a valve 30 which permits pressure air to pass to an actuator 40 when the air in the tyre has fallen to a predetermined value. The actuator includes an element 122, 174 biased to one position and movable against the bias to a warning position when the pressure air is received by the actuator, and a latch mechanism responsive to movement of the actuator element to the warning position to hold the element in that position. The element in the warning position, when the vehicle carrying the system is in motion, causing a warning to be given to the driver. As illustrated, the valve is located within the tyre and comprises a member 70 biased in one direction by a spring 72 and by tyre pressure air entering chamber 58 via apertures 76 and filter 78, and biased in the opposite direction by a bellows 80 precharged to the desired tyre inflation pressure. A drop in tyre pressure to a predetermined value will result in valve member 70 being displaced by the bellows to allow flow of pressure air via a tube (not shown) into chamber 96 of the actuator. Thus, diaphragm 122, rods 132, 144, magnet assembly 146 and latch element 138 are displaced against bias of spring 162 into a warning position. Simultaneously the rod 110 is biased by spring 120 to a position (Fig. 4, not shown) in which the diaphragm &c. are retained in the warning position. The magnet assembly in rotation of the wheel, on which the actuator is mounted, activates a sensor 44 and thus causes a low pressure warning on indicator (54) (Fig. 1, not shown). The actuator may alternatively comprise a piston 174 and a rod 182 with an annular recess 188 which coacts with spring biased plunger 192 to lock the piston and rod in the warning position. In both arrangements, spring 162 biases the rod 132, 182 to the illustrated position on manual depression of pin 110 or plunger 192. The actuator may be responsive to air from each of a pair of twin wheels. |
