Pipe joints or couplings – Molded joint – Weld
Patent
1996-10-04
1999-03-30
Arola, Dave W.
Pipe joints or couplings
Molded joint
Weld
285328, 285906, F16L 1302
Patent
active
058879102
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a connection structure for a connector such as a branch pipe or branch metal fixture used in a fuel rail such as a high-pressure fuel manifold or high-pressure fuel block and, more particularly, to a connection structure for a branching connector used in a high-pressure fuel rail which supplies fuel under high pressure reaching 1000 kgf/cm.sup.2 or more in a diesel internal combustion engine.
BACKGROUND ART
A conventional connection structure of this kind for a branching connector is shown in FIG. 7, where a main tube 11 acts as a fuel rail provided with a channel 11'. A hole 11" extends through the wall around the main tube 11, and is in communication with the channel 11' in the main tube. The hole 11" is of simple circular cross section. A branch tube 12 acting as a branching connector is inserted in the hole 11". The branch tube 12 has a connection end 12' which is neither enlarged nor shrunk. Under this condition, the connection end 12' is brazed at 13 to the main tube, thus forming a connection structure.
In this connection structure built by the prior art technique, fluid under high pressure amounting to 1000 kgf/cm.sup.2 or more is constantly and repeatedly supplied. The pressure is rapidly changed. Vibrations are given especially from the engine. The ambient temperature is elevated and lowered, causing the relative dimensions of the opposite members (the opposite seat surfaces) to vary. Especially, where the diameter of the branching connector is small compared with the diameter of the main tube 11, when the main tube is brazed to the branching connector, local heating deteriorates the mechanical strength near the brazed portion 13. As the tubes get fatigued due to vibrations, cracks are easily produced. As a result, leakage of the fuel may occur frequently.
In view of the foregoing problems with the prior art technique, the present invention has been made. It is an object of the invention to provide a connection structure for a branching connector used in a high-pressure fuel rail, the connection structure having a connected portion in which two components are brazed together firmly. The connection structure is further characterized in that stress in the branching connector near the connected portion due to fatigue is effectively dispersed. If the connection structure is placed in position and repeatedly supplied with fluid under high pressure which varies rapidly, or if the relative dimensions are varied by the variations in the pressure of the supplied fluid, application of vibrations, or temperature variations, cracks are effectively prevented from being produced in the branching connector near the connected portion. This eliminates the possibility of leakage of the fuel.
DISCLOSURE OF THE INVENTION
In order to achieve the foregoing problem, the present invention provides a connection structure for a branching connector used in a high-pressure fuel rail having a main tube provided with a channel, the main tube being further provided with at least one hole extending vertically through the wall around the main tube and in communication with the channel. The at least one hole forms a dished seat portion having a staircase-like cross section or an inclined surface. The branching connector has an enlarged portion near its one end, the enlarged portion extending to an inclined wall toward the front end. This enlarged portion has a connection head portion near its front end. The connection head portion totally conforms in cross-sectional shape with the seat portion. The head portion is brought into abutting engagement with the seat portion. The mutually engaging portions are brazed together, thus forming the connection structure.
In one feature of the invention, the aforementioned connection head portion is formed by having the connection head portion or a sleeve fitted thereover. The connection head portion is formed integrally with one end of the branching connector. Alternatively, the outer surface of the connection head portion forms an enlar
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Arola Dave W.
Budzyn Ludomir A.
Casella Anthony J.
Hespos Gerald E.
Usui Kokusai Sangyo Kaisha Limited
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