Patent GB-930188-A (GB)
Title: Pneumatic pressure regulating transducer valves
Inventor: HOLLAND FRANCIS JOSEPH
IPC: F16D65/78
Filed: 1960-09-29
Abstract: 930,188. Fluid pressure brakes. F. J. HOLLAND. Sept. 29, 1960, No. 33429/60. Class 103 (1). [Also in Group XXIX] A valve device for use in a servo-assisted braking system comprises a first valve means, including pilot and secondary valve members 56, 48 respectively, releasably sealing an air chamber 94 and a fluid pressure regulating chamber 88, a second valve means, including pilot and secondary valve members 58, 60 respectively, releasably sealing the fluid pressure regulating chamber 88 and a fluid supply chamber from each other, the first and second valve means being operatively engaged by a movable diaphragm means 16 subjected to the effect of a spring 70 to normally close valve means 58, 60 and open the other valve means 56, 48, a master control force (e.g. in the form of a variable vacuum pressure introduced into chamber 18 via connection 22) is provided for urging the diaphragm means 16 in the direction opposing the spring 70 in order to change the magnitude of the fluid pressure in the chamber 88, means being provided to apply to the diaphragm means 16 a balancing fluid pressure source corresponding to the magnitude of the fluid pressure in the chamber 88 and an antivibration and flutter reducing means (42) forms part of the coupling between the diaphragm 16 and the first and second valve means. The embodiment shown in Fig. 4 controls the operation of an hydraulic slave cylinder (not shown) which is operated by a differential pressure across a movable diaphragm connected to the piston of the slave cylinder for increasing the hydraulic fluid pressure to the wheel cylinders of a vehicle braking system. The output of the slave cylinder is also connected to the port 74 of the valve device 10, and vacuum is supplied to valve conection 34 from a vacuum source and the vacuum output coupling 92 is connected to the vacuum regulating chamber of the diaphragm section of the hydraulic slave cylinder. A variable vacuum pressure is connected to coupling 22 of the valve device for supplying a regulating control pressure in chamber 18, the opposing chamber being exposed to atmosphere via openings 154. Operation of a vacuum control pressure to chamber 18 urges the diaphragm 16 to the left against the action of spring 70 to close the valves 48 and 56 and lift valve seat 58 from its seal 64. Further movement causes valve seat 60 to open and allow vacuum from the source to be connected to the output coupling 92. Operation of the vacuum operated slave cylinder (not shown) exerts a pressure to the solid end of stem 36 of the valve device to balance the vacuum side of chamber 18 to return the valve to its position illustrated. Fig. 5 shows an alternative embodiment illustrating an air suspended valve device in which the diaphragm 16 is replaced by a stepped piston 162, 164 such that the valve is subjected to pressure by a pedal-operated master cylinder via connection 188 to apply an opposing force to a spring 70 and close air valve seats 48 and 56 and open valve seat 58 and, if necessary, the secondary vacuum valve seat 60 and open controlled vacuum chamber 88 to the vacuum supply via coupling 34 and allow vacuum to pass via coupling 92 to the controlled vacuum chamber of the diaphragm section of the vacuum operated slave cylinder (not shown) to move the latter diaphragm and increase the hydraulic fluid pressure to the wheel brake cylinders. The increased hydraulic fluid pressure is also supplied through coupling 190 to the end of the smaller piston section 164 in the highpressure chamber. When the forces acting against the opposing ends of the stepped piston are balanced the valve is in a state of equilibrium and spring 70 moves the stem assembly towards the right to close the vacuum valve seats and thereby prevent further evacuation of the chamber 88. Other embodiments are disclosed in the Specification including a wholly vacuum controlled air-suspended valve and alternative means for applying a variable control pressure to the diaphragm 16 by means of a helical spring 108 mounted in a hollow sleeve 104 abutting a hollow stem 36 fast with the diaphragm 16, the end 114 of sleeve 104 forming a pivotal attachment of an actuating mechanism e.g. a brake pedal linkage, as shown in Fig. 2 or, as shown in Fig. 3, a solenoid coil 122 controlled by a variable resistance 132 operated by a plunger 38 connected to the brake pedal (not shown). Other embodiments disclose alternative valves suitably modified to conform to the vacuum suspended principle, and the embodiments disclosed may be suitably modified for use in compressed air regulated systems.