GB694475A - Improvements in or relating to tyre inflation control systems - Google Patents

Abstract

694,475. Valves. BENDIX-WESTINGHOUSE AUTOMOTIVE AIR BRAKE CO. Oct. 30, 1951 [Oct. 30, 1950; Oct. 30, 1950], No. 25302/51. Class 135 [Also in Group XXXIV] A tyre inflation control system for a pneumatictyred vehicle wheel 16 comprises a control valve 20 carried by the wheel and having an outlet chamber 28 communicating with the tyre, an inflation check valve 58 which allows flow of pressure air from a conduit 34 into the chamber 28 but prevents return flow from the tyre, a deflation check valve 66 normally preventing communication between the outlet chamber 28 and an exhaust chamber 30 open to atmosphere, and means carried by the control valve 20 for opening the deflation check valve to reduce the pressure in the tyre. Fig. 1 shows a pressure-air supply 10 connected via a pressure-indicating valve 40 with an axle mounting 50 to communicate with the conduit 34 in the wheel axle. Pressure air is supplied from the source 10 to a deflation control valve 86, the chamber of which is normally open to atmosphere via a hollow plunger 88 and a pipe 94. Depression of the plunger 88, closes the pipe 94 and operates spring loaded interconnected ball valves 704, 96 respectively to close the hollow plunger and allow pressure air to flow into the valve chamber and thence via a pipe 92, and a conduit 82 in the wheel axle, to a pressure chamber 78 in the control valve 20 where it acts on a spring loaded diaphragm 72 to depress a rod 74 and thereby open the deflation check valve 66. The check valves 66 and 58 are interconnected by a loosely mounted pin 84 so that opening of one valve prevents opening of the other. In operation, to increase the tyre pressure, valve 40 is set to the desired pressure whereupon check valve 58 is opened to admit pressure to the tyre. When the desired pressure is reached in the tyre, valve 40 is operated to connect pipe 32 and conduit 34 to atmosphere, to remove the pressure on seals 54, 56 in the axle mounting, and the check valve 58 closes to prevent return flow. To reduce the tyre pressure, valve 40 is set to the desired lower pressure and plunger 88 then depressed for a sufficient time to effect deflation of the tyre below the desired lower pressure. Release of the plunger 88 connects conduit 82 to atmosphere, thus relieving the pressure on seals 52, 54 in the axle housing, and allows check valve 66 to close whereupon check valve 58 opens to inflate the tyre to the set pressure. Valve 40 is then set to exhaust. Fig. 3 shows a layout for four wheel-tyres 126 wherein a single conduit 134 is used for each tyre to effect both increase and decrease in tyre pressure: The arrangement comprises a main pressureair supply 132 feeding a pressure-control valve 150 and connected by a non-return valve 164 with an auxiliary pressure-air supply 158 which feeds a deflation control valve 154. The pressure-air supply from valve 150, which may be via valve 154, is selectively directed to all or each of the tyres by a valve bank 166, 168, 170, 172, 174. The single conduits 134 each comprise an axle duct 140 and a wheel hub duct 142 communicating with each other between pressure seals 146, 148, pressure on which is maintained only during inflation or deflation of the tyre, and each wheel carries a control valve 128. Figs. 4 and 5 show one form of control valve 128 wherein an inflation check valve 208 and a deflation check valve 210 are separately arranged in the respective parts of a two-part outlet chamber 192, and each check valve is associated with a spring-loaded pressure-responsive piston 220 or 230 arranged to operate only under a pressure in its feed chamber 234 which exceeds the maximum operating pressure in the tyre. The operation of tyre inflation is as described above for valve 20, but for deflation of the tyre, full supply pressure is admitted' to the inlet chamber 200 of the valve 128 by operation of the valve 154 causing depression of both pistons 220, 230, the piston 220 having a rod 228 which opens the deflation check valve 210 and the piston 230 having a rod 236 which holds the inflation check valve closed. Re-inflation of the tyre to a desired pressure is effected by operation of the valve 150 as described for valve 40 in Fig. 1. Figs. 6 and 7 show an alternative form of control valve 128 wherein the deflation check valve 210 has a pin 260 arranged to hold the inflation check valve 208 closed when the said valve 210 is caused to open by a rod 258 of a pressure-responsive piston 252 on admission of full supply pressure to an inlet chamber 240 by operation of valve 154, Fig. 3. The inflation check valve 208 is operated on pressures below full supply pressure as determined by the setting of valve 150, the operating pressure air being conducted from the inlet chamber 240 via a duct 248 to a chamber 250 above valve 208. Fig. 8 shows the feed valve 150, operatively associated with the deflation control valve 154. The valve 150 is of the self lapping type and comprises an exhaust chamber 268 and a control chamber 270 defined by spaced diaphragms 264, 266 which are interconnected by a hollow plunger 272. The plunger. 272 opens into the exhaust chamber 268 and co-operates at its lower end with a spring loaded exhaust valve 274 which is connected to an intake valve 276. Depression of the plunger 272 closes the plunger bore on the valve 274 and opens the intake valve 276 to allow pressure air from conduit 136 to pass into the conduit 134 and thence to the tyres. Such depression of plunger 272 is effected by compression of a spring 282, acting thereon, by rotation of screw 278 the handle 152 of which passes over a graduated dial. In operation, with handle 152 turned clockwise to a desired pressure, the intake valve 276 is held open until the pressure acting on the diaphragm 266 in the control chamber 270, which communicates with the conduit 134 via a choke opening 271, reaches the set pressure, whereupon the plunger is moved upwardly to allow the valve 276 to close. Rotation of the handle 152 to zero setting releases plunger 272 from the exhaust valve 274 and connects conduit 134 with atmosphere via chamber 268 and passages 298, 294, 296 in the valve 154. The valve 154 has a spring loaded plunger 292 depression of which closes the exhaust opening 296 and opens a valve 302 to allow full supply pressure from tank 158 via conduit 160 to pass into the exhaust chamber 268 and thence via the hollow plunger 272 to the conduit 134. The plunger 272 is held raised by the pressure acting on diaphragm 264 which latter is of larger area than diaphragm 266. To effect depression of the plunger 292 a lever 310 is arranged to depress an operating rod 304 bearing on the plunger 292 when the screw 278 is turned anti-clockwise by handle 152.