Patent GB-1159741-A (GB)
Title: Improvements in or relating to Fluid Control Valves.
Inventor: OBERTHUR HEINRICH
IPC: B60T13/58
Filed: 1967-08-11
Abstract: 1,159,741. Hydraulic brakes; hydrodynamic brakes; valves; Bowden mechanisms. ALFRED TEVES G.m.b.H. 11 Aug., 1967, No. 36933/67. Headings F2E, F2F, F2K and F2V. In a control valve for fluidpressure operated systems, such as the hydraulic brake systems of motor vehicles which have a hydrodynamic brake 7 to relieve the friction brakes, two pistons 23, 22 are disposed in a valve casing 21, one of the pistons 22 being hollow and provided with a sealing disc 29 which, in the position of the valve shown in Fig. 2, closes a chamber 31 against a chamber 25 by the force of a spring 30 thereby closing the connection between a charging cylinder 8 via connection 28 and the connection 32 leading to a pressure accumulator 9 of the hydrodynamic brake 7, the other piston 23 taking the form of a stepped piston with a valve plate 33 disposed at its forward end under the influence of a further spring 34. In operation, when the stepped piston 23 is subjected to hydraulic pressure from a master cylinder 4 via lines 6 and 10, connection 35 and an annular chamber 36, the piston 23 is displaced in the direction of the hollow piston 22 to close the air connection via the piston bore 24 in the hollow piston to an atmosphere connection 26 subsequent further movement of the piston 23 results in the piston 22 being displaced against the force of the spring 30 to lift the sealing disc 29 off its seat so that the connection is made from the pressure accumulator 9, via a connection 32, to the charging cylinder 8, via the connection 28, so that the hydrodynamic brake 7 comes into operation. When the piston 23 is no longer subjected to hydraulic pressure via the inlet 35, the pistons are pushed back by the force of the spring 30 to return the sealing disc 29 to its seat and close the air accumulator connection 32 from the chamber 25 and from the charging cylinder connection 28. The piston 23 is moved by the force of the spring 34 and further separated from the hollow piston 22 to restore the connection between the charging cylinder connection 28 via the chamber 25, the piston bore at 24 and the chamber 26 to the atmosphere aperture 27. The valve may be operated manually by means of a Bowden cable so that a pressure nipple 39 is brought into effect against a spring 40, a push rod 38 being displaced via a spring 41 clamped thereto, such that the push rod 38 slides in the stepped piston 23, in the direction of the hollow piston 22 until it abuts the valve plate 33. Further displacement of the push rod results in the hollow piston 22 being forced forwardly by the valve plate 33 and the sealing disc 29 is lifted off its seat to move the valve into its operative position. The manual operating device may be adapted to be locked in any position. As shown in Fig. 1, the front brakes may be applied directly via line 5 from the hydraulic master cylinder 4 and the rear brakes are operated via line 6 through a compensating valve 12 which controls the pressure applied to the brake cylinders of the rear axle in relation to the output of the hydrodynamic brake 7.