Fluid handling – Systems – Flow path with serial valves and/or closures
Patent
1989-03-06
1990-01-30
Fox, John
Fluid handling
Systems
Flow path with serial valves and/or closures
137614, F16L 2900
Patent
active
048966975
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a coupling for connecting liquid conduits, comprising an insert nipple and receiving nipple, said nipples being axially moveable in relation to each other for connection and disconnection, said insert nipple comprising a stationary sleeve with a sealing valve body spring-biased and inwardly axially movable therein, said receiving nipple having an outer sleeve, an inner spring-biased and inwardly axially movable sealing sleeve and a stationary valve central stay which in disconnected condition sealingly cooperates with the sealing sleeve.
Developments in hydraulic technique are moving towards the use of higher operating pressure because of the fact that higher power can be obtained from smaller, lighter machines or tools, instead of increasing the flow quantity, resulting in considerably higher pressure drops (loss of power) in the hydraulic system and larger machines. This increase of operating pressure places greater demands on the sealing elements of the hydraulic system, of which sealing joints containing O-rings are one type. The O-rings are affected by pressure so that the rubber tends to spread at high pressure levels into the play or gap between the surrounding construction elements on the pressure-free side, resulting in permanent damage to the O-ring, and consequently considerable reduced sealing effect and service life. A usual method of dealing with the increased operating pressure is to mount O-rings with greater hardness, e.g. 90.degree. Shore. Such a solution is simple and relatively inexpensive but has the disadvantage that the elasticity and flexibility of the O-ring is reduced due to the increased hardness, thus resulting in quicker and increased wear. In constructions with spring-return plungers or piston rods, etc. (e.g. quick couplings), less radial compression of an 0-ring having a hardness of 90.degree. Shore is required to reduce the friction of the seal, with resultant reduction in service life of this sealing joint. One method of solving this problem is to use ordinary support rings or so-called compact seals, the purpose of which is to prevent the O-ring from spreading into the play or gap between the construction elements. Since the parts included are not vulcanized, no stress state occurs, thus preventing the properties of the various materials to be fully utilized. Well reinforced seals tend to separate due because of fatigue due to the different degrees of elasticity of the materials used. One drawback with the sealing constructions of O-ring type described above is that their service life is shortened by pulsating operating pressure since the O-ring slides to and for in its sealing position as the pressure changes. The support ring must also abut adjacent pipes and shafts, which means that softer plastic material such as polytetrafluorethylene or thermoplastic elastomers must be used, making the construction sensitive to high pressure peaks.
The object of the present invention is to provide a spill-free quick coupling which satisfies the desires of manufacturer, user and servicing to the greatest possible extent and which has improved seals with increased service life and which will withstand high pressure peaks.
This is achieved by the invention in that the sealing sleeve is provided at its outer end portion with an inner wedge seal arranged to sealingly cooperate with a wedge-forming conical outer surface on the front end portion of the outer sleeve and comprising a conical support ring; that an inner seal is arranged in a groove in the outer sleeve for radial sealing cooperation with the sealing sleeve which is free from sealing grooves; that the distance between circumferentially located locking balls in the outer sleeve and said inner seal is greater than the distance within which the sealing sleeve is axially movable inside the outer sleeve; that the sealing sleeve is provided on its inner side with a seal which in disconnected condition is arranged to seal against a substantially cylindrical sealing surface of a sealing valve body of th
REFERENCES:
patent: 2850298 (1958-09-01), Clerk
patent: 3097867 (1903-07-01), Salomon
patent: 4124228 (1978-11-01), Morrison
patent: 4289164 (1981-09-01), Ekman
patent: 4685490 (1987-08-01), Medirck et al.
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