Sealed reservoir for brake master cylinder

Claim 1

A fluid reservoir adapted for mounting on a brake master cylinder comprising: a casing having an inner wall and an upper opening for storing an amount of brake fluid; a resilient seal cap of an elastic material detachably coupled over the upper opening of said casing to air-tightly seal the interior of said casing, said seal cap defining an interior air space with the upper surface of brake fluid in said casing, said cap having at the center thereof a vent hole and an annular boss forming an inner bore opening to the vent hole; a first annular valve body of elastic material fixedly mounted on said cap concentric with the center of said cap and spaced a predetermined distance radially inwardly from the inner wall of said casing; a second valve body formed in a mushroom configuration and secured at its neck portion to said annular boss of said cap, said second valve body being made of elastic material and having a circular head portion opposed to said first valve body; a valve plate having its inner edge carried by said annular boss of said seal cap between said first and second valve bodies, with the outer edge of said plate being spaced radially inwardly from the inner wall of said casing, said valve plate having at least one opening to permit the flow of air therethrough, said valve plate co-operating with said second valve body to provide an inlet check valve permitting the flow of air through said opening in said valve plate into said interior air space and further co-operating with said first valve body to provide an outlet check valve permitting the flow of air out from said interior air space to the exterior; and means for communicating the interior space to the atmospheric air by way of said inner bore in said annular boss and said inlet and outlet check valves.