Reservoirs for liquid pressure control systems

Claim 1

A hydraulic fluid reservoir for a hydraulic control system, said system comprising a master cylinder and a remote slave cylinder connected to the master cylinder by a conduit, said reservoir being connected to said master cylinder and comprising a body having a mouth, a detachable cap mounted on the mouth of the body and removable for replenishing the reservoir with hydraulic fluid through said mouth, a flexible diaphragm secured in position by said cap and also removable for replenishing the reservoir with hydraulic fluid, said diaphragm dividing the reservoir into two separate and non-communicating chambers, one of said chambers being an air chamber below said cap vented to atmosphere through an aperture in the cap and the other of said chambers being a chamber below said diaphragm for containing hydraulic fluid and connectable to the master cylinder, an inlet port defined in a wall of the reservoir body for initial charging of hydraulic fluid into the other of said chambers without necessitating the removal of the cap and diaphragm, and a non-removable closure plug located in the inlet port for subsequent sealing thereof after the initial charging, wherein the inlet port and the closure plug are so constructed and arranged as to allow excess hydraulic fluid in the other of said chambers to exit therefrom past the closure plug when a predetermined pressure differential exists across the closure plug and as to prevent ambient air from being introduced to said other of said chambers, and wherein said initial charging of hydraulic fluid is effected through said port by connecting said port to a source of vacuum with said closure plug removed, disconnecting said port from said source of vacuum, connecting said port to a source of said hydraulic fluid and placing said plug in said port.