Patent GB-1243523-A (GB)
Title: Anti-skid control system for piston-controlled hydraulic braking systems
Inventor: LEIBER HEINZ
IPC: B60T8/44
Filed: 1968-11-01
Abstract: 1,243,523. Hydraulic brake systems; antiskid control of brakes. TELDIX G.m.b.H. 1 Nov., 1968, No. 51984/68. Heading F2F. In a master cylinder operated hydraulic vehicle brake system having an antiskid controller with inlet and outlet valves 12, 13 respectively for controlling admission to and release from the brake wheel cylinders of hydraulic fluid, the main pressure pipeline system 7 is automatically replenished with brake fluid when the brake fluid content of the main pressure pipeline system has fallen to a predetermined level during a controlled braking operation. As shown in Fig. 1, when a movable wall 17 of a storage chamber 16 has been displaced sufficiently by fluid released from the wheel cylinder, a switch 30 is actuated to close the inlet valve 12 and energize an electromagnetically operated valve system to reverse the connections of vacuum and air to a pneumatic booster 2 thereby withdrawing the master cylinder piston 3 and returning brake fluid from the storage chamber 16, through a non-return valve 19, to the main pressure line system 7. Normal connections to the booster 2 are automatically restored when the movable wall 17 has been sufficiently displaced by spring 18 to open the switch 30. A pressure switch 32 causes actuation of the engine starter if chamber 16 becomes completely filled. In a modification, Fig. 2 (not shown), the reversing valves are operated mechanically and a differential pressure switch (36) is connected between the pipelines 9 and 10 for closing the inlet valve 12 when the booster connections are reversed. As shown in Fig. 3, if the forward travel of the master cylinder piston exceeds a given limit, a valve 45 is opened mechanically to connect one side of an auxiliary piston 42 to vacuum thereby displacing piston 40 to pump brake fluid from the reservoir 6 to the main pressure line system 7. In modifications, the piston pump is replaced by an electrically driven rotary pump which may be energized only when replenishment is required, Fig. 4 (not shown), or which may be energized continuously during braking, Fig. 5 (not shown), a valve (49), which is opened in synchronism with the outlet valve 13, being provided in the delivery line between the pump and the main pressure line system 7, whereby as much brake fluid is replenished as is released through the outlet valve 13. As shown in Fig. 6, proportional replenishment is achieved by a fluid pressure operated followup mechanism. Fluid P may be compressed air or liquid. In other arrangements, a piston pump is used for replenishment. The piston may be spring- biased in either direction and driven electromagnetically in the other direction. In one arrangement, Fig. 7 (not shown), the piston (71) is operated for one cycle when a movable wall (17) of the storage chamber (16) is displaced sufficiently to close an electric circuit. In another arrangement, Fig. 8 (not shown), in which the pump (84) has a smaller capacity than the storage chamber (16), an additional chamber (82) having a capacity similar to that of the pump (84) is connected through a flow restrictor (81) to the storage chamber (16) and through a non-return valve (86) to the pump (84). A diaphragm (88) in the additional chamber (82) is deflected by fluid coming from the storage chamber to close an electric circuit to energize the pump, which then operates for several cycles in which the additional chamber (82) is emptied and refilled to cause cyclic opening and closing of the electric circuit until the storage chamber 16 can no longer refill the additional chamber (82). In another arrangement, Fig. 10 (not shown), the pump (98) operates when a movable wall (110) of the storage chamber (16) is displaced sufficiently to position a transmission member (109) in the path of a member (104) moved, with lost motion, with the piston of the pump so that a switch (102) is closed at the end of the spring-driven stroke of the pump to produce an electromagnetically driven stroke. When the storage chamber (16) has been sufficiently emptied, the transmission member (109) is withdrawn thereby terminating the operation of the pump.