Patent GB-1027556-A (GB)
Title: Improvements in or relating to motor vehicle braking systems
IPC: F16D57/04
Filed: 1964-10-12
Abstract: 1,027,556. Fluid-pressure brakes; hydro-dynamic brakes; disc brakes. H. TEVES, E. A. TEVES, and M. TAUSEND, [trading as ALFRED TEVES MASCHINEN UND ARMATURENFABRIK KOMM.-GES.]. Oct. 12, 1964 [Oct. 11, 1963; Feb. 22, 1964; March 3, 1964], No. 41544/64. Headings F2E and F2F. In a motor vehicle braking system which includes a hydrodynamic transmission brake arranged to be controlled by a valve operable in accordance with pressure in a pressure fluid supply line to a friction brake, a second valve is also provided responsive to the torque produced by the hydrodynamic brake and which comprises a piston floating in a cylinder between connections to a pressure fluid source and to the first valve, the piston having a passage through it controlled by a valve member responsive to the torque produced by the hydrodynamic brake. In one embodiment, Fig. 1, friction brakes on the vehicle wheels comprise actuating cylinders 7 which are supplied with hydraulic fluid by a servo-operated master cylinder 6 under control of a pedal-operated master cylinder 5 via conduits 25, 26 and a valve 8. The latter consists of floating piston 19 slidable in a cylinder and having a passage 20 closable by a valve member 18 responsive to pressure difference on opposite sides of a diaphragm 10 caused by operation of a hydrodynamic brake 2 which is energized at the same time as the friction brakes via a valve 4 a control chamber of which is connected by line 27 to chamber 23 of valve 8 and which on operation admits air from a line 28 to a charging cylinder 3 for filling the brake 2 with working fluid. The pressure built up in the hydrodynamic brake drives the working fluid through an external circuit 15, 16 through a heat exchanger 17 and the pressure difference across lines 15, 16 is applied to the diaphragm 10 by connections 13, 14 to chambers 11, 12. When this pressure difference rises sufficiently the valve member 18 closes passage 20 to prevent further increase in pressure in chamber 23. As the speed of transmission shaft 1 reduces valve member 18 will allow gradual increase in pressure in the chamber 23 and hence in the cylinders 7 of the friction brakes. In the modification of Fig. 2 the valve member 18 is made responsive to the torque of the hydrodynamic brake 2 by connecting it to the casing of brake 2 which is allowed limited float to operate member 18. Fig. 3 shows an all pneumatic control system for operating compressed air friction brakes, servo-operated cylinder 6 being omitted and master cylinder 5 being replaced by a driver's valve 29. Valve 4 would of course be modified for control by air instead of liquid pressure in line 27. Conversely, the air line 28 in Fig. 1 can be replaced by an hydraulic pump supply to a modified charging cylinder 3 including an isolating piston (Fig. 4, not shown) for use with an all-hydraulic friction brake system. The Fig. 5 embodiment is similar to that of Fig. 1 but the valve 8 is replaced by a modified structure 35 comprising a diaphragm 37 operable both on valve member 18 and on a valve member 38 controlling a ball valve 40 in a trailer friction brake system ineluding trailer brake cylinders 45, so that as the passage 20 is closed to cut off supply to the tractor brake cylinders 7 the ball valve 40 is allowed to close to cut off the trailer brake cylinders. The diaphragm 37 otherwise functions as the diaphragm 10 in Fig. 1. In Fig. 6, the friction brake operates on the transmission shaft 1 and is combined with the hydrodynamic brake by forming the rotor 46 of the hydrodynamic brake with disc faces having friction linings 54 for engagement with annular axially movable friction members 53 applied by cylinders 51 which are supplied by the servooperated master cylinder 6. The pedal-operated master cylinder is also modified in that the floating piston 19 is arranged in the pressure space 60 of the master cylinder, the control member 18 being guided in the end wall of the master cylinder to which a casing 36 containing a diaphragm 37, operating as the diaphragm 10 of Fig. 1, is secured. Fig. 7 shows a single annular friction member 53 operating on one side only of the rotor 46 of the hydrodynamic brake.