Fluid return system for antilocking vehicle brakes

Claim 1

In an antilocking control system for vehicle brakes of the type having a brake-fluid-pressure line leading to a wheel brake slave cylinder and including outlet valve means for intermittently bleeding off fluid selectively to reduce the pressure transmitted to the slave cylinder, the improvement comprising, in combination: accumulator means connected for receiving fluid bled off by said outlet valve means and composed of a member having a movable wall and defining an expansible chamber therewith and spring means for urging said movable wall in the direction to reduce the volume of said chamber; a positive displacement pump having an inlet connected to said accumulator means and an outlet connected to the pressure line; pump inlet valve means connected to the inlet of said pump for normally allowing fluid to flow unidirectionally to said pump from said accumulator means; and means carried by said movable wall for retaining said inlet valve means in its open condition when said accumulator means approaches its empty condition for permitting fluid to be circulated indefinitely back and forth between said accumulator means and said pump.