GB952374A - Apparatus and devices for automatic control and supervision of the pressure of the tyres of vehicle wheels - Google Patents

Abstract

952,374. Fluid pressure control valves &c. L. C. HORTA, and P. L. GARCIA. June 20, 1961 [June 20, 1960], No. 22325/61. Heading F2V. [Also in Divisions B7 and G3] The tyre pressures of a vehicle are controllable whilst the vehicle engine is running by engine driven pumps 18, 18<SP>1</SP> which pressurize continuously pipes 8, 12 and 16 connected to the front, rear and spare tyres respectively via actuators M operatively coupled to the tyre inflation valves 7, the pressure in said pipes being determined by operator-controlled continuously acting blow-off valves 20, 20<SP>1</SP> and the actuators M comprising pressure-operated spring loaded differential pistons 114 serving to unseat the tyre valves 7 at all pressures above a predetermined minimum. As shown the front and rear supply pipes 8, 12 are fed from separate but interconnectable chambers 37, 37<SP>1</SP> which are provided with electrically operated discharge valves 22, 22<SP>1</SP> electrically connected via the ignition switch 25 and a further switch 27 to open when the circuit is broken. Each actuator M comprises a tubular body 101 screwed to the valve body 7 and having clamped thereon, by a cap 107, a banjo-connection 104 providing a side entry for pipe 9 or 13 leading to the associated rotary joint. The pipe 9, 13 provides pressure air to the space in the body 101 adjacent the tyre valve body 7 to act on the end of a hollow piston rod 114 and to pass therethrough to act on the piston head 111 to effect movement of the piston, against a spring 118 to unseat the tyre valve 34. The underside of the piston head 111 is maintained at atmospheric pressure via a duct 121 in the body 101 and is sealed from the pressure space by a seal 115 slidably surrounding the piston rod 114. Where the actuators M are not provided with control springs 118 ensuring a'minimum tyre pressure, a pressure responsive device 201 may be provided in the circuit of each of the rapid. discharge valves 22, 22<SP>1</SP> to ensure rapid exhaust of the pipes, and consequent closure of the tyre valves on a fall in pressure in the system below a predetermined minimum. Each device 201 comprises a movable contact 38 carried on a spring loaded bar 209 engageable by a resilient abutment member 208 which is frictionally sleeved over a pin 203 connected to an expansible pressure responsive diaphragm 201 exposed to the pressure chamber 37. Expansion of the diaphragm is limited by an adjustable abutment 206 for the pin 203, and movement of the sleeve 208 on such expansion is limited by a fixed cap 207 of the switch so that the sleeve is forced on to an enlarged diameter portion 205 of the pin to a position determined by the setting of stop 206. On retraction of the pin by fall in pressure on the diaphragm the sleeve 208 is carried thereby eventually to move the contact 38 to open circuit position. On continued retraction of the pin, the sleeve 208 is held by the contact bar and caused to slide along pin 203 on to a reduced diameter end 204 thereof, in which position it permits the contact carrier 209 to be returned by its springs 216 to close the contacts and reset the valve.