Quick take-up master cylinder

Claim 1

In a master cylinder having a molded reservoir, a separate master cylinder body to which said reservoir is attached, and a quick take-up valve module, the improvement comprising: said master cylinder reservoir having a bottom having a tubular spigot extending downwardly and integrally molded therewith to define a valve chamber, said spigot extending into a recessed boss formed as a part of said master cylinder body and engaging the bottom of the boss recess to define therewith the lower part of said valve chamber; integrally molded retainer means extending from said reservoir bottom and snapping over said boss to retain said reservoir on said master cylinder body, said boss having means cooperative with said retainer means for that purpose, and a valve body integrally molded with said reservoir bottom in the upper portion of said spigot and extending into the fluid chamber of said reservoir above the upper surface of said bottom, said valve body having a passage formed axially therein and opening into the reservoir fluid chamber at its upper end, and other passage means radially adjacent said spigot and connecting the reservoir fluid chamber and said valve chamber said valve body further having a shouldered recess opening downwardly into said valve chamber; a valve seat member positioned within said valve chamber and having a flange operatively engaging the shoulder of said valve body shouldered recess and a valve-containing extension extending into said shouldered recess, a check valve passage extending from the lower portion of said valve chamber through said valve seat member and mating with said valve body passage and having check valve means therein acting to permit fluid flow only from the lower part of said valve chamber to said reservoir under control of a differential pressure exerted thereacross, valve seat support means extending downwardly from said flange and engaging the bottom of the boss recess while permitting fluid flow between the lower part of said valve chamber and said check valve passage, a valve seal sealingly engaging said valve seat member and said valve body at said shouldered recess to prevent fluid flow between said valve seat member and said valve body, said valve seal also having a flared lip extending generally radially outward and downward beyond said valve seat member and said valve body and engaging the inner wall of said spigot to close said other passage means against fluid flow from said valve chamber to said reservoir but permitting fluid flow through said other passage means from said reservoir to said valve chamber; and a continuously open restricted flow passage bypassing said check valve means between the fluid chamber of said reservoir and said lower part of said valve chamber and providing a controlled leak accommodating a delayed pressure equalization between said reservoir and the lower portion of said valve chamber under static pressure conditions; said check valve opening to a predetermined blow-off pressure generated in the lower portion of said valve chamber during a predetermined master cylinder actuation stage to vent the lower portion of said valve chamber to said reservoir.