Welding joint for fuel tank

Abstract

A welding joint for a fuel tank includes a cylindrical portion and an annular weld portion. The weld portion has a multi-layer structure formed by layering an inner layer member made of a resin alloy material obtained by alloying a modified HDPE, to which a functional group having a high affinity to a hydroxyl group of EVOH is introduced, and EVOH, or by alloying the modified HDPE, normal HDPE and EVOH, and an outer layer member which uses the HDPE resin and / or modified HDPE resin and has high weldability to the fuel tank. Each of the inner and outer layer members is heat-welded to the fuel tank at a corresponding welding end surface. In a vicinity of at least one of the welding end surfaces of the inner outer layer members, a flow preventing portion that prevent a molten part of the inner layer member from flowing the outer layer member is provided.

Description

technical field [0001] The present invention relates to a resin joint for connecting a piping tube or a connector to a resin fuel tank, and more particularly to a resin welded joint which is welded to the fuel tank and constitutes a connecting portion. Background technique [0002] A fuel tank installed in a motor vehicle is integrally provided with a fitting for connecting the fuel tank to a pipe or a connector for guiding fuel injected from a filler port to the fuel tank. [0003] Hitherto, for example, rubber tubes (or rubber hoses) have been used as tubes for guiding fuel injected from a filler port to a fuel tank. However, in recent years, from the viewpoint of environmental protection, regulations for preventing fuel from permeating to the outside through hoses have become strict. Therefore, a rubber-resin composite material pipe composed of a rubber hose having a resin barrier layer, a rubber pipe made of fluororubber having fuel permeation resistance, or a resin pip...

AI Technical Summary

Problems solved by technology

[0034] However, the water resistance of EVOH is not always sufficient

Thus, there is a problem in this configuration that in the case where the weld is exposed to moisture for a long time, the weld will absorb moisture, resulting in deterioration of the fuel penetration resistance of the weld and a decrease in weld strength

Additionally, welded portion 250 of welded joint 248 is easily exposed to moisture

Therefore, in the case where the entire welded portion 250 is made of such a resin alloy material, fuel permeation resistance and weld strength may deteriorate over time.

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