Hydraulic circuit for an anti-locking braking system

Claim 1

In an anti-lock braking system of the type including a master brake cylinder for applying braking pressure, said master brake cylinder having a hydraulic fluid reservoir, hydraulic pressure modulator means for regulating the braking pressure to prevent brake locking, said modulator means having a relieved hydraulic fluid chamber, and hydraulic fluid line means operatively connecting said relieved hydraulic fluid chamber to said master brake cylinder for transferring hydraulic fluid in said relieved hydraulic fluid chamber to said reservoir during regulation of the braking pressure, the improvement comprising: means for preventing air trapped within said fluid line means from being transferred to said modulator means, said preventing means comprising said reservoir being positioned entirely at a location above an inlet connection of said fluid line means to said master brake cylinder, whereby such trapped air is caused to move upwardly by its buoyancy through said fluid line means and said reservoir; means for, in the event of the occurrence of a leak in said fluid line means, ensuring a required supply of hydraulic fluid for said relieved hydraulic fluid chamber, said ensuring means comprising buffer chamber means in said fluid line means for accumulating therein hydraulic fluid, said buffer chamber means being positioned at a level below said inlet connection; and means for throttling the flow of hydraulic fluid from said relieved hydraulic fluid chamber to said reservoir, and thereby for preventing depletion of the accumulation of hydraulic fluid in said buffer chamber means, said throttling means comprising a restriction of the internal size of said fluid line means, said restriction being located between said buffer chamber means and said inlet connection.