Power plants – Pressure fluid source and motor – Pulsator
Patent
1994-07-25
1995-12-26
Look, Edward K.
Power plants
Pressure fluid source and motor
Pulsator
60585, 92 98D, F15B 700, B60T 1126
Patent
active
054776821
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a hydraulic reservoir and master cylinder assembly in particular for hydraulic systems on automobiles.
It is known from GB-A-1539879 to provide a hydraulic clutch control system comprising a master cylinder, a reservoir, and a slave cylinder which are assembled together with conduit, and then the entire system is filled with hydraulic fluid prior to installation on a vehicle.
The present invention relates to a master cylinder and reservoir assembly which is particularly suitable for use in a pre-filled hydraulic clutch control system.
The present invention provides a compact, cheap master cylinder-/reservoir assembly.
Accordingly there is provided a hydraulic master cylinder and reservoir assembly having a master cylinder body with a fluid reservoir, and a master cylinder bore with a piston assembly sealingly reciprocal within the bore, the assembly being characterised in that the fluid reservoir having at least a portion thereof concentric with the master cylinder bore and being sealed from atmosphere by rolling diaphragm, the inner periphery of the diaphragm being sealed to the piston assembly, and the outer periphery of the diaphragm being sealingly slidable relative to an internal surface of the reservoir allowing the volume of fluid within the reservoir to expand or contract.
It is an advantage of this construction that no sliding piston seal is in direct contact with the atmosphere.
The primary seal directly separates the pressure chamber from the reservoir chamber and the classic secondary seal is replaced by the deformable diaphragm which is substantially stationary during piston reciprocation and is airtight.
The master cylinder body may include a cylindrical liner spaced from the internal wall of the body forming a chamber therebetween, said chamber constituting a part of the reservoir.
The metal liner may have a mouth at one end and an end wall at the other end, the liner being capable of limited axial movement in the body, and the end wall of the liner forming a recuperation valve controlling the flow of hydraulic fluid between the master cylinder bore and the reservoir.
It is an advantage for the liner to be both rigid, of metal or other material, and of a material of low elasticity, and in this latter case, for the liner to be provided with a calculated functional play, and supported by the body after a slight expansion due to the effect of the pressure.
The master cylinder may have an outlet port which receives a conduit in form of a plastic flexible pipe, the conduit being retained in position is the outlet port of the hydraulic master cylinder and reservoir by chordal pins that cut into the external surface of the conduit as the pins are forced into position.
The piston assembly may comprise a push rod, a seal retainer which is an interference fit on the push rod, and a piston primary seal which is located co-axially between the push rod and the seal retainer.
The piston assembly may be sealed to the bore by a primary seal comprising a seal ring, preferably an elastomeric ring seated in a cup, preferably PTFE, which supports the radially outer peripheral surface of the elastomer ring and its side adjacent the piston, the outer peripheral margin of the cup being supported by a backing ring, preferably a PTFE backing ring (PTFE=polyfluroethylene).
This seal allows the piston assembly to tilt relative to the axis of the bore.
The outlet portion of the master cylinder body may be surrounded by an annular seal, which co-operates with a portion of the end wall of the liner to regulate the flow between the reservoir and the master cylinder bore.
The annular seal is kept in position by a coaxial ring clip at the outlet port, and this clip serves to limit the axial movement of the liner in the master cylinder body.
In another configuration of the invention, the outlet port of tile master cylinder body receives the conduit which is a force fit, the outlet port having annular ribs therein to grip and retain the conduit and seal said conduit into the outlet port. This arrange
REFERENCES:
patent: 4779713 (1988-10-01), Tomala et al.
patent: 5052279 (1991-10-01), Limbacher et al.
patent: 5107680 (1992-04-01), Hojnacki et al.
patent: 5138936 (1992-08-01), Kent
Automotive Products France SA
Germain Lee A.
Look Edward K.
Milliken Paul E.
Nguyen Hoang
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