Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for a pipe – conduit – or cable
Patent
1997-01-30
1999-07-27
Knight, Anthony
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for a pipe, conduit, or cable
277630, F16J 1502
Patent
active
059277262
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a sealing system for connecting a valve for fuel injection to a fuel rail in combustion engines, especially to preclude O-ring leakage at low temperatures.
BACKGROUND OF THE INVENTION
In usual sealing systems of this kind having an O-ring 32 as a sealing element, the sealing element is seated in a radial outer groove 26 of the valve housing 22 whereby the end of the valve housing to be connected to the fuel rail 10 is formed by a groove limiting flange 23 which abuts a ring surface 18 at the bottom 16 of a circular cylindrical rail branch 12 incorporating the valve housing 22, and which borders the bore 11 of the rail 10 at the branch-off point (see FIG. 8).
The disadvantage of such a sealing system is that the sealing elements used in low-temperature conditions must have special material properties to suit this application, yet they fail at temperatures below minus 40.degree. C. when the swelling of the O-ring caused by the fuel is no longer sufficient to avoid leakage of the sealing element radially outside; please refer to G. Streit and M. Achenbach: "Functionality of elastomer seals at low temperatures by the example of O-rings, part 2: Influence of fuels on the sealing performance at low temperatures", in "Kautschuk, Gummi, Kunststoffe KGK, Internationale Fachzeitschrift fur polymere Werkstoffe" ("Caoutchouc, Rubber, Synthetic Material KGK, International Technical Journal for Polymeric Material"), 10/93 (October 1993, 46th year) p. 812 ff.
SUMMARY OF THE INVENTION
The invention has the objective to create a sealing system of the aforementioned kind which guarantees reliable sealing of the plug-in connection of the injection valve and the pertaining branch of the fuel rail even at temperatures below minus 40.degree. Celsius and in case of insufficient or lack of swelling of the sealing element (O-ring) (for example during extended periods between operation).
The advantage of the invention is that sealing rings without special qualities may be used as sealing elements at low temperatures and that leak-tightness is still achieved even under low temperatures or due to temporary lack of fuel, the swelling can no longer compensate for the cold-caused shrinkage of the sealing element.
The invention is based on the recognition that a sealing element which is not fixed to the wall of the installation space will shrink radially inwards onto its support whereby the radial inside sealing effect is increased whereas the radial outside sealing effect decreases.
The form-closed contact of the sealing element according to the invention at the branch of the fuel rail causes the sealing element to be held on the rail branch before the injection valve is inserted and secured.
In one configuration according to the present invention, a clamp-like sealing element secures the coherence of injection valve and rail branch, with the participation of the flange adaptor which may be formed in one piece with the fuel rail.
WO 91/11610 (corresponding to U.S. Pat. No. 5,044,340) discloses both a typical sealing system located at the end 14 of the injection valve 10, the injection valve end being adjacent to the fuel rail 18; this is a configuration which does not fully comply with the known sealing systems described at the beginning, since no flange of the valve housing is in contact with the branch 16 of the fuel rail 18, but the piston-shaped valve end 14 "telescopically" engages with the branch 16; as well as a sealing system similar to the typical one, located at the end 12 of the valve 10 adjacent to a distributor 22, where subsequent to an outside collar 32 of the valve housing replacing the known flange for axial limitation of the circular groove 26 for installation of the sealing element 34, a continuation of the groove bottom as extreme end of the valve housing reaches without contact into a bore 20 of the distributor 22, whereas the basically L-shaped sealing element 34 which is axially longer than radially thick and which is located with its thick portion in the cir
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Streit, G. and Anchenbach, M., "Funktionalitat von Elastomerdichtungen bei tiefen Temperaturen am Beispiel von O-Ringen", KGK Kautschuk Gummi Kunstsoffe 46, Jahgang, Nr. Oct. 1993, pp. 812-823.
Achenbach Manfred
Krumeich Peter
Streit Gerhard
Beres John L.
Knight Anthony
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