GB1468821A - Fluid pressure control valves - Google Patents

Abstract

1468821 Proportioning valves; load responsive braking AUTOMOTIVE PRODUCTS Ltd 8 May 1974 [15 May 1973] 23080/73 Heading F2F A vehicle braking system fluid pressure control valve 11 having a body 13 with an inlet 12 connected to a master cylinder and an outlet 14 connected to a rear wheel motor cylinders comprises a movable valve member 39 co-operable with a valve seat 41 to control communication between the inlet 12 and the outlet 14; the valve member 39 is screw-threadedly attached to a plunger 23 having a free end 59 engaged with resilient means (not shown) connected to an axle of the vehicle to apply a load to the plunger 23 which is related to the loading of the vehicle, and the actual load applied to the plunger 23 by the resilient means is determined by the position of an abutment (e.g. 53) the plunger 23 is urged by the resilient means towards the abutment 53 and the abutment 53 is movable with respect to body 13 whereby the operation of the control valve 11 can be modified by suitable positioning of the member. As shown in Fig. 1, the valve seat 41 is formed as part of a plunger 43 and the plunger 43 is urged by a compression spring 45 seating upon a shoulder 47 of plunger 23 into contact with the axial abutment 53 which is provided on a plug 49. The plug 49 is screwed into a bore 15 in the body 13 to an extent which affects the actual load applied to plunger 23 and carries a seal 57. In operation fluid pressure is initially transmitted from inlet 12 via a first chamber 61, a passage 35 in plunger 23, open valve 39, 41, radial slots 40 in valve member 39, and a second chamber 63 reaches a level sufficient to overcome the resilient means the plunger 23 moves away from plug 49 to close valve 39, 41 increased pressure in the first chamber 61 subsequently moves the plunger 23 to open valve 39, 41. In this way the outlet pressure is proportioned relative to the inlet pressure. In the embodiment of Fig. 2 the valve 11 has a plug 67 with an axial bore 69 containing a plunger 76 with a seal 84 abutting plunger 43. The position of the plunger 76 is alterable by means of a grub screw 78 provided with a lock nut 79. A shoulder 82 on plunger 76 proves an abutment for plunger 23. In the modification of Fig. 3 (not shown) the plug (86) is similar to plug 67 but a radial aperture (88) is provided to allow a feeler gauge to be inserted between the grub screw (78) and the plunger (76). A flexible boot (90) prevents ingress of dirt.