GB1373637A - Tyre pressure warning systems - Google Patents

Abstract

1373637 Tyre pressure indicating systems CHRYSLER UNITED KINGDOM Ltd 2 Oct 1972 [10 Nov 1971] 52193/71 Heading B7C A tyre pressure indicating system comprises a pair of switches 24, 25 mounted in spaced apart positions on a vehicle part 27 rotatably mounting a wheel 10 carrying a pneumatic tyre 12, a tyre pressure responsive device mounted on the wheel 10, and a switch striker 22 operatively connected to the pressure responsive device whereby, in use, when the tyre pressure is at a predetermined level, the device positions the striker such that in its rotation with the wheel it passes between the switches 24, 25 at a point equidistant from each switch, but if the tyre pressure rises above, or falls below, this level by a given amount the device moves the striker 22 such that in its rotation with the wheel it strikes and operates the switch 24 or 25 respectively thereby to actuate a warning device, e.g. of a visual and/or audible nature. The given amount by which the pressure must change before the striker 22 operates the switch 24 or 25 is determined by the distance of each switch from the striker when the latter is in the position it assumes at the predetermined pressure level, and, in order that the given amount may be altered, the switches may be adjustably mounted on a corner 26 secured to the part 27. In one embodiment, Figs. 1, 2, the pressure responsive device comprises a hollow cylinder 13 divided into two chambers by a slidable piston 18 which has a seal 19 and is connected to a rod 20 carrying the striker 22 the right-hand chamber (as seen in Fig. 2), being open to the tyre pressure through a tube 16 and a member connected to, and holding open, the tyre inflation valve 17, and the left-hand chamber being vented to atmosphere and containing a spring 23 which opposes the tyre pressure in the right-hand chamber and thus determines the predetermined pressure level referred to above. The cylinder 13 has an externally screw-threaded hollow spigot 14 through which the rod passes and by means of which and a nut 15 it is secured to the wheel. The pressure responsive device of Figs. 1 and 2, may be modified (see Fig. 3, not shown), by containing the pressurized air from the tyre in a flexible bellows (30) located in the right-hand chamber of the cylinder 13, in which case both chambers of the cylinder are vented to atmosphere and the piston seal is omitted. A further form of pressure responsive device is shown in Fig. 4, wherein a hollow casing 31 replaces the cylinder and a flexible diaphragm 32 is provided instead of the piston.