Expansible chamber devices – Cylinder detail
Patent
1987-07-31
1990-03-20
Garrett, Robert E.
Expansible chamber devices
Cylinder detail
921701, 60588, 285921, B60T 1122, F16J 1002
Patent
active
049091310
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention is related to master cylinders that are adapted to be pre-filled and pre-bled before being taken to an assembly site such as an automotive plant. Typically, such master cylinders comprise an elongated, hollow, cast metallic body defining an internal pressure chamber and including a pressure producing piston. A cap on one end of the body closes the chamber and has an opening for the piston rod. The pressure chamber is connected to an integral or remote reservoir for replenishing any fluid loss in the system. The reservoir has a filling opening, and a vented cap is mounted on the filling opening. Prefilled master cylinders of this general construction are shown for example in U.S. Pat. No. 4,407,125 entitled "Liquid Pressure Apparatus," issued on Oct. 4, 1983 to David Parsons and assigned to Automotive Products plc of Warwichsire, England.
Master cylinders of this general construction are generally satisfactory but are relatively expensive and complicated to produce. Further, there is a problem with maintaining master cylinders of this type since frequently a mechanic will remove the cap of the reservoir to replenish the hydraulic fluid but fail to remove the bellows positioned within the open upper end of the reservoir with the result that hydraulic fluid is introduced into the bellows rather than into the working portion of the reservoir.
SUMMARY OF THE INVENTION
This invention is directed to the provision of an improved master cylinder assembly having a construction which provides a more efficient and less expensive assembly.
This invention is further directed to the provision of a master cylinder which has provision to obviate the problem of inadvertently filling the bellows rather than the reservoir itself.
According to a basic feature of the present invention, the master cylinder is constructed as a pair of cylinder housings that are assembled by telescopically inserting the end of one cylinder housing into the other.
In one embodiment of the invention, a locking ring connects the two cylinders housings together in their assembled position and a single O-ring is mounted between the two cylinder housings to seal the pressure chamber from atmospheric pressure and to form a seal between the high and low pressure sides of the pressure chamber.
In another embodiment of the invention, the cylindrical housings are formed of a plastic material and are snap secured to each other by insertion of one member within the other member. The coacting means which operate to snappingly secure the two housings together comprise an external circumferentially extending lip on one of the cylindrical housings coacting with an internal circumferentially extending lip on the other of the housing. This embodiment also has means to ensure that the housing members will be properly angularly located relative to each other in their assembled position. The locating means comprises a locator portion projecting outwardly from one of the housing member and a slot adjacent the open end of the other housing member. As the members are telescopically inserted one within the other, the slot in the outer member slides over the locator portion on the inner member to angularly locate the outer member relative to the inner member. In the preferred form of this embodiment the locator portion of the inner member is constituted by a fitting surrounding the discharge port of the inner member, the fitting extends downwardly from the inner member, the other member includes an upstanding reservoir portion, the slot in the other member is provided on the underside of that member, and the slot and fitting coact during the assembly process to ensure that the second member is mounted on the first member with the reservoir in a generally upstanding disposition.
The features described above have particular application to a master cylinder of the pull type but also have application to push type master cylinders.
According to another feature of the invention, the bellows in the reservoir is connected to the vent c
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Barker David C.
Kassin Charles A.
Kassin Marina
Nix Richard A.
Automotive Products plc
Garrett Robert E.
Kapsalas George
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