JP2008162572A - Weld joint for fuel tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weld joint for a fuel tank having a weld portion for being to be welded to a resin fuel tank with stable and sufficient welding strength even in the case of structuring at least the weld portion by using a resin alloy material obtained by alloying a modified HDPE (high density polyethylene) alone, or alloying HDPE with EVOH (Ethylene Vinyl alcohol Copolymer). <P>SOLUTION: The weld joint 2 to be integrated with a rim portion of an opening of the fuel tank by thermal welding is structured by using a resin alloy material of EVOH with a modified HDPE, and the whole of a tip of the weld portion 16 on the fuel tank side is structured of a highly-weldable layer 34 made of a HDPE resin having good weldability, and the weld portion 16 is welded to the fuel tank in the highly-weldable layer 34 part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin joint for connecting a tube or connector for piping in a resin fuel tank, and more particularly to a resin weld joint which is thermally welded to a fuel tank to form a connection portion.

A fuel tank mounted on an automobile is integrally provided with a joint for connecting a tube or a connector for guiding fuel injected from a fuel filler port to the fuel tank.
Here, for example, in the case of a tube that guides fuel from a fuel filler port to a fuel tank, conventionally, a rubber tube (rubber hose) has been used. Environmental regulations that restrict permeation are becoming stricter. Therefore, as a tube for piping, a rubber resin composite tube in which a rubber hose is combined with a barrier layer of a resin with low fuel permeability, fluorine with low fuel permeability. Rubber tubes made of rubber or resin tubes made of resin have been adopted.
Conventionally, as a connection structure of these tubes to the fuel tank, for example, a connection structure as shown in FIG. 12 is adopted.

In FIG. 12, 200 is a resin fuel tank, and 202 is a resin weld joint. The welding joint 202 is integrated with the fuel tank 200 by heat welding.
The welding joint 202 has a tubular portion 204 as a tube insertion portion, and an annular flange portion 206 is provided so as to protrude on the outer peripheral surface of the tubular portion 204.
A resin tube 208 guides the fuel injected from the fuel filler port to the fuel tank 200. As shown in FIG. 12B, a bellows portion 210 is provided to give flexibility.

In FIG. 12B and FIG. 13, reference numeral 212 denotes a connector (quick connector), and the resin tube 208 is connected to the welding joint 202 via the connector 212.
The connector 212 includes a resin connector main body 214 and a resin retainer 216.

  The connector main body 214 includes a nipple portion 218 on one side in the axial direction, and a socket-like retainer holding portion 230 that elastically inserts and holds the retainer 216 on the other side.

The nipple portion 218 is a portion that press-fits the resin tube 208 in an externally fitted state and fixes it, and has a retaining portion having a plurality of annular protrusions 232 on the outer peripheral surface spaced in the axial direction and having a sawtooth cross section. Is formed. A plurality of O-rings (seal rings) 234 are held on the inner peripheral side.
On the other hand, the socket-like retainer holding portion 230 is provided with an arc-shaped window portion 236, and a partial ring-shaped portion 238 having a corresponding arc shape.

  The retainer 216 is elastically deformable in the radial direction as a whole, and includes an arc-shaped groove 240 that fits elastically with the partial ring-shaped portion 238 in the retainer holding portion 230 and a flange-shaped portion 206 on the welding joint 202 side. A taper-shaped guide surface 242 for guiding the insertion in the axial direction and elastically expanding the entire retainer 216 and an arc-shaped engaging recess 244 for engaging the flange-shaped portion 206 are provided.

In this connection structure, the end of the resin tube 208 is forcibly pressed into and fixed to the nipple portion 218 of the connector main body 214.
At that time, the end portion of the resin tube 208 is expanded in diameter as shown in FIG. 12B by press-fitting into the nipple portion 218, and the nipple portion 218 is tightened in the radial direction with a strong tightening force.
The end of the resin tube 208 is fixed to the connector main body 214 by the tightening force and the biting action of the annular protrusion 232 provided on the nipple portion 218.

At the same time, the retainer 216 is mounted and held on the connector main body 214, and the connector 212 is externally inserted into the cylindrical portion 204 of the welding joint 202 in this state.
At this time, the retainer 216 held by the connector main body 214 is elastically expanded and deformed by the hook-shaped portion 206, and when the hook-shaped portion 206 reaches the engaging recess 244, the retainer 216 is elastically contracted and deformed again. Thus, the hook-shaped portion 206 and the engaging recess 244 are engaged.
At the same time, a portion of the cylindrical portion 204 on the tip side from the flange-shaped portion 206 is fitted into the O-ring 234 on the inner peripheral side of the connector main body 214, so that the cylindrical portion 204 and the connector main body 214 are connected to each other. The space is hermetically sealed.

On the other hand, it is envisaged that the resin tube 208 is inserted directly (directly) into the cylindrical portion 204 of the welding joint 202 without using the connector 212 and connected.
A welding joint for connecting such a connector (quick connector) or directly connecting a tube for fuel piping is integrally joined to the fuel tank by thermal welding as described above, but the welding joint is attached to the fuel tank. When the tube connecting portion is integrally joined by heat welding, the following problems occur.

  Conventionally, HDPE (High Density Polyethylene) resin has been used as the outer layer material of the fuel tank. Therefore, it is required that the weld joint integrated therein can be welded to the fuel tank.

  For this welding, it is conceivable that the entire welding joint including the cylindrical portion is made of the same material HDPE resin. However, although HDPE resin has excellent weldability to the fuel tank, it is resistant to fuel permeation (low Fuel permeability) is insufficient, and there is a problem that fuel permeates from there.

  In order to solve this problem of low fuel permeability, the following Patent Document 1 includes an outer layer material having a weldability with a fuel tank and a resin material having a low fuel permeability (barrier property). It is disclosed that a welded joint is formed by laminating the inner layer material in the radial direction.

FIG. 14 shows a specific example thereof.
In FIG. 14, reference numeral 246 denotes a resin fuel tank, which is an outer layer 246-1 and an inner layer 246-2 made of HDPE resin, and a barrier layer 246-2 of EVOH (ethylene-vinyl alcohol copolymer) resin excellent in low fuel permeability. Are laminated.
Reference numeral 248 denotes a resin welding joint that is welded and integrated with the fuel tank 246. The welding joint 248 includes a tubular portion 252 that serves as a connection portion (insertion portion) of the tube 258, and a welding portion 250 at the base end portion thereof. And is welded to the fuel tank 246 at the welded portion 250.
In the cylindrical portion 252, the outer layer 254 and the inner layer 256 are made of different resin materials. Specifically, the outer layer 254 is made of the same resin material as the welded portion 250, and the inner layer 256 is made of a barrier material such as PA (polyamide) resin having a lower fuel permeability than this.
A hose band 260 clamps the tube 258 in a fitted state.

  In the welded joint 248 having this structure, when the outer layer 254 and the welded portion 250 in the cylindrical portion 252 are made of the same HDPE resin having high weldability to the fuel tank 246, the HDPE resin has low fuel permeability. (For that reason, in the welding joint 248 shown in FIG. 14, the inner layer 256 of the cylindrical portion 252 is made of a barrier material). Therefore, even if low fuel permeability can be secured for the cylindrical portion 252, HDPE The welded portion 250 made of resin is in a bare state, and the problem is that the fuel in the fuel tank 246 permeates to the outside through the welded portion 250.

  In view of this, the present applicant, in the previous patent application (the following Patent Document 2), as shown in FIG. 15, the entire weld joint 262, more specifically, the tubular portion 264 and the welded portion welded to the fuel tank 246. Resin alloy material obtained by modifying the entire weld joint 262 including H.266 with a modified HDPE (high density polyethylene) obtained by introducing a functional group having a high affinity for the hydroxyl group of EVOH, alone or together with EVPE. It has been proposed using

  EVOH has been conventionally known as a material having excellent gas barrier properties. A resin alloy material obtained by alloying the above-mentioned modified HDPE with the HDPE alone or together with the HDPE is used as a fuel tank depending on the HDPE contained therein. In addition to having excellent weldability with respect to H.246, it also has extremely low fuel permeability (barrier property) due to EVOH. Therefore, as shown in FIG. 15, the cylindrical portion 264 and the welded portion 266 are provided. In addition to the advantage that the entire number of welding joints 262 can be made of a single material, thereby reducing the number of man-hours required for molding and making the welding joint 262 inexpensive, it is good for the cylindrical portion 264 and the welding portion 266. It can be expected that such a low fuel permeability can be imparted and that a high weldability can be imparted to the welded portion 266. PA is also a material having excellent gas barrier properties like EVOH, and a resin alloy in which modified HDPE obtained by introducing a functional group having a high affinity for the amine group of PA alone or with HDPE is alloyed with PA. The same advantage can be expected even if the welding joint 262 is formed using a material.

  However, when such a welding joint 262 is welded to the fuel tank 246, the welding strength of the welding joint 262 to the fuel tank 246 is actually different depending on various welding conditions, for example, the welding joint 262 and the fuel at the time of welding. It has been found that stable welding strength cannot always be obtained sufficiently due to variations caused by conditions such as the melting temperature, melting time, melting allowance (melting thickness) of the resin in the tank 246, welding pressure, and welding time. .

  The welded portion 266 of the weld joint 262 of FIG. 15 configured using the above resin alloy material has improved weldability as compared with the case where this is composed of EVOH alone, but the weldability is as high as that of HDPE resin. For this reason, when the welding joint 262 is welded to the resin fuel tank 246 by the welding portion 266, there is a variation in welding, such as whether the welding is strong or insufficient depending on the welding conditions. And it is thought that the same situation arises when fuel low permeability resin other than EVOH or PA is used.

JP 2002-254938 A JP 2006-143172 A

  The present invention is based on the above circumstances, and at least the welded portion is stable even when the modified HDPE is used alone or together with HDPE, for example, using a resin alloy material formed by alloying with EVOH or PA. The present invention has been made for the purpose of providing a welding joint for a fuel tank that can be welded to a resin fuel tank with sufficient welding strength.

  In order to achieve this object, the welding joint in the fuel tank of the present invention has a tubular portion as a connecting portion of a tube for a pipe or a connector and a welding portion at a base end portion, and the welding portion is made of resin. A welding joint that is integrally welded to a peripheral portion of an opening of a fuel tank, wherein at least the welded portion is made of a modified HDPE (high density polyethylene) having affinity with a low-permeability barrier resin. Or a resin alloy material formed by alloying with the barrier resin together with HDPE (high density polyethylene), and at the tip of the welded tank side of the welded part, the weldability to the fuel tank A high weld layer composed of a high HDPE resin and / or a modified HDPE resin is formed, and the weld portion is the fuel tank with the front end surface of the high weld layer as a weld surface. A welding joint in a fuel tank adapted to be welded to a pipe, or a tubular portion as a connecting portion of a tube or connector for piping and a welded portion at a base end portion, wherein the welded portion is made of resin A welding joint that is thermally welded and integrated with a peripheral portion of an opening of a fuel tank, wherein at least the welded portion is a hydroxyl group of EVOH (ethylene vinyl alcohol copolymer) or an amine group of PA (polyamide). The modified HDPE formed by introducing a functional group having a high affinity is used alone or together with the HDPE and using a resin alloy material formed by alloying with the EVOH or PA. A high weld layer made of HDPE resin or / and modified HDPE resin having high weldability to the fuel tank is formed at the tip portion. A weld joint in the fuel tank in which the welded portion of the distal end surface of the adhesive layer as a welding surface are no to be welded to the fuel tank. Here, at least the welded portion can be formed by using a modified HDPE obtained by introducing a functional group having a high affinity for the hydroxyl group of EVOH, alone or together with HDPE and a resin alloy material formed by alloying with EVOH. Alternatively, a modified HDPE obtained by introducing a functional group having a high affinity for the amine group of PA can be used alone or a resin alloy material formed by alloying with PA together with HDPE.

  In the present invention, it has a cylindrical portion as a connecting portion of a tube or connector for piping and a weld portion at the base end portion, and is welded to the peripheral portion of the opening portion of the resin fuel tank at the weld portion. A weld joint to be integrated, wherein at least the weld portion is made of a modified HDPE having an affinity with a low-permeability barrier resin alone or together with HDPE and alloyed with the barrier resin. In addition, the entire front end of the welded portion on the fuel tank side is composed of a high welded layer made of HDPE resin or / and modified HDPE resin with high weldability to the fuel tank over the entire circumference. The welded portion is welded to the fuel tank with the front end surface of the highly welded layer as a welded surface, or a tubular portion or a base as a connecting portion of a tube or connector for piping. A weld joint that is thermally welded and integrated with a peripheral portion of an opening of a resin fuel tank at the weld portion, and at least the weld portion is an EVOH hydroxyl group or PA. The modified HDPE formed by introducing a functional group having a high affinity with respect to the amine group of the resin alone or together with the HDPE and using the resin alloy material formed by alloying with the EVOH or PA, The entire front end portion on the fuel tank side is composed of a high weld layer made of HDPE resin or / and modified HDPE resin having high weldability to the fuel tank over the entire circumference, and the front end surface of the high weld layer The welding portion may be welded to the fuel tank with the welding surface as the welding surface.

  The present invention also has a tubular portion as a connection portion of a tube or connector for piping and a weld portion at the base end portion, and is welded to the peripheral portion of the opening portion of the resin fuel tank at the weld portion. A welded joint that is integrated with each other, and at least the welded portion uses a modified HDPE having an affinity for a low-permeability barrier resin alone or together with HDPE and alloyed with the barrier resin. And the outer peripheral side portion or inner peripheral side portion of the tip portion on the fuel tank side in the welded portion or the intermediate portion therebetween is partially weldable to the fuel tank. It is configured as a high weld layer made of high HDPE resin and / or modified HDPE resin, and the front end surface of the weld alloy portion made of the resin alloy material and the front end surface of the high weld layer are weld surfaces. The welded portion is welded to the fuel tank, or has a tubular portion as a connecting portion of a tube or connector for piping and a welded portion at the base end portion, and is made of resin at the welded portion. A welding joint that is thermally welded and integrated with a peripheral portion of an opening of a fuel tank, wherein at least the welded portion introduces a functional group having a high affinity for a hydroxyl group of EVOH or an amine group of PA. The modified HDPE is composed of a resin alloy material formed by alloying the modified HDPE with the EVOH or PA alone or together with the HDPE, and an outer peripheral side portion or an inner peripheral side portion of a tip portion on the fuel tank side in the welded portion. Alternatively, the intermediate portion between them may be configured as a highly welded layer made of HDPE resin or / and modified HDPE resin having high weldability to the fuel tank over the entire circumference. , It can be assumed that solution attaching portion is welded to the fuel tank front end surface and the tip surface of the high welding layer portion made of the resin alloy material of the welding portion as a welding surface.

  According to a fifth aspect of the present invention, in the third aspect, the outer peripheral surface of the highly welded layer is a tapered surface that gradually becomes smaller in diameter as it moves away from the tip surface on the fuel tank side toward the cylindrical portion. It is characterized by.

  According to a sixth aspect of the present invention, there is provided the molding die according to the fourth aspect, wherein the high welding layer is set in a state where the high welding layer formed in advance on a molding die for molding the welding joint using the resin alloy material. The support portion is provided in a radial pattern so as to be in contact with the molding surface and prevent deformation of the highly welded layer when the resin alloy material is injected into the mold and molded.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the entire welded portion and the cylindrical portion excluding the highly welded layer are configured using a single resin alloy material. It is characterized by that.

  As described above, in the present invention, a high weld layer made of HDPE resin or / and modified HDPE resin having high weldability to the fuel tank is formed at the tip of the weld tank on the fuel tank side. The entire tip on the fuel tank side is composed of a high weld layer made of HDPE resin or / and modified HDPE resin that has high weldability to the fuel tank over the entire circumference, and the welded portion of the weld joint is a part of the high weld layer According to the present invention, a higher welding performance can be imparted to the welded portion formed by using the above resin alloy material, whereby the welded joint can be attached to the fuel tank. The welding joint can be welded to the fuel tank with a sufficiently stable and strong welding strength regardless of the welding conditions at the time of welding.

  On the other hand, according to the fourth aspect of the present invention, the outer peripheral side portion or the inner peripheral side portion of the tip portion on the fuel tank side in the welded portion or the intermediate portion therebetween is partially constituted by the high welded layer over the entire circumference. With the tip surface of the part made of the resin alloy material and the tip surface of the high weld layer as the weld surface, the weld portion is welded to the fuel tank, and even in this case, by the action of the high weld layer, It is possible to weld the welded portion of the welded joint to the fuel tank with stable and strong welding strength.

  Further, in the fourth aspect, the portion made of the resin alloy material of the welded portion is also welded to the fuel tank over the entire circumference with the tip surface on the fuel tank side as the welded surface. It is possible to better suppress the fuel in the tank from permeating outside through the high welding layer.

  Next, in claim 5, the shape of the highly welded layer in claim 3 is a shape in which the outer peripheral surface forms a tapered surface that gradually decreases in diameter as it moves away from the front end surface on the fuel tank side toward the cylindrical portion. is there.

  In claim 3, when forming the weld joint, a high weld layer is formed in advance, and a resin alloy material is injected into the mold in a state in which the high weld layer is set in the mold, thereby forming the welded portion. However, at this time, the high welding layer set inside the mold is turned up by the pressure of the resin alloy material injected into the molding die, and the high welding layer is turned to the welded portion at the planned position. There is a possibility that they are not well integrated by two-color molding.

However, according to claim 5, the outer peripheral surface of the high weld layer is a tapered surface that gradually becomes smaller in diameter as it moves away from the front end surface on the fuel tank side toward the cylindrical portion, so that the high weld layer can be formed when the resin alloy material is injected. It is possible to prevent the turning-up as described above.
Therefore, according to the fifth aspect, the highly welded layer can be well integrated with the welded portion at the predetermined position by two-color molding.

  Next, according to a sixth aspect of the present invention, when the high weld layer is configured according to the fourth aspect, when the resin alloy material is injected into the mold and molded with the high weld layer set in the mold, the molding of the mold is performed. In this case, the high weld layer can be well integrated with the weld portion by two-color molding.

In the present invention, the entire welded portion and the tubular portion excluding the highly welded layer can be configured using a single resin alloy material.
If it does in this way, the whole welding joint can be comprised with a substantially single resin material, the man-hour for shaping | molding can be reduced, and the cost of a welding joint can be made cheap.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, 10 is a resin fuel tank, and an outer layer 10-1 made of HDPE resin and an inner layer 10-3 sandwiched a barrier layer 10-2 made of EVOH resin and having excellent low fuel permeability in a sandwich shape. It has a laminated structure.

Reference numeral 12 denotes a resin welding joint, which has a cylindrical portion 14 that serves as a connecting portion of a tube for piping (hereinafter simply referred to as a tube) and a welding portion 16 at the base end thereof.
A tube for piping is press-fitted into the cylindrical portion 14 in an externally fitted state, and is connected to the fuel tank 10 via the welding joint 12.

On the outer peripheral surface of the cylindrical portion 14, a retaining portion 19 having a plurality of annular protrusions 18 spaced apart in the axial direction and having a sawtooth cross section is provided.
The retaining portion 19 has a function of retaining the tube by causing each annular projection 18 having a sharp tip to bite into the inner surface of the tube.

The tubular portion 14 is also formed with an annular O-ring groove 20 on the tip side thereof, and an O-ring having elasticity as a sealing material is fitted therein.
Further, the cylindrical portion 14 is formed with a stopper portion 22 having a substantially annular shape at a position on the left side of the retaining portion 19 in the drawing.
When the tube is inserted into the cylindrical portion 14, the stopper portion 22 abuts on the tip of the tube and functions to define the amount of insertion.

The welded portion 16 has a substantially disc-shaped flange portion 24 and a falling portion 26 that falls from the outer peripheral end thereof toward the fuel tank 10 and forms an annular shape around the opening 28 of the fuel tank 10. In the falling part 26, the peripheral part of the opening 28 of the fuel tank 10, specifically, the outer layer 10-1, is integrated by thermal welding.
The welding joint 12 is also integrally formed with an annular projecting portion 30 projecting toward the fuel tank 10 inside the falling portion 26. Here, the protrusion 30 is used for connection to a resin housing 32 such as a valve disposed in the fuel tank 10.

2 and 3 show the shape of the welding joint 12 before welding to the fuel tank 10.
As shown in FIG. 2, in this embodiment, the entire tip of the welded portion 16, specifically, the falling portion 26, on the fuel tank 10 side, extends to the fuel tank 10 all around the opening 28. The high-weld layer 34 having a high weldability is integrally formed by two-color molding over the entire front end surface of the main portion 36 of the falling portion 26. .
In this embodiment, the thickness of the high welding layer 34 is 2 mm (the welding margin at the time of welding is 2 mm).

The welded portion 16 is thermally welded to the fuel tank 10 with the front end surface of the highly welded layer 34 as a welded surface 38.
In the present embodiment, the entirety of the weld joint 12 excluding the high weld layer 34, specifically, the main portion 36 and the flange portion 24 of the falling portion 26 in the weld portion 16 and the whole including the cylindrical portion 14 are the following materials: In other words, a modified HDPE (high density polyethylene) introduced with a functional group having a high affinity for the hydroxyl group of EVOH (ethylene vinyl alcohol) alone or with a normal HDPE and alloyed with EVOH, or a resin alloy material of PA A modified HDPE having a functional group having a high affinity for an amine group is composed of a resin alloy material obtained by alloying PA with a single or together with ordinary HDPE.

On the other hand, the high weld layer 34 is made of HDPE resin having a higher weldability to the fuel tank 10 than the resin alloy material, and more specifically, a higher weldability to the outer layer 10-1.
In addition, you may use the mixed material of said modified | denatured HDPE resin or normal HDPE resin, and modified | denatured HDPE resin as this highly welded layer 34. FIG.

  In this embodiment, as shown in FIG. 2B, the high weld layer 34 has a lower surface and an upper surface in FIG. 2, that is, a surface opposite to the weld surface 38 on the fuel tank 10 side. The outer peripheral surface of the main portion 36 extends downward from the outer peripheral surface, more specifically, a surface substantially perpendicular to the outer surface of the fuel tank 10, and the inner peripheral surface is the main portion. The inner peripheral surface of 36 is extended to the fuel tank 10 side, specifically, a surface slightly inclined with respect to the vertical direction in the drawing.

In the present embodiment, modified HDPE is used instead of ordinary HDPE as a material for alloying with EVOH or PA, for the following reason.
Ordinary HDPE has poor affinity for EVOH or PA. Therefore, even if it is intended to be alloyed with EVOH or PA, EVOH or PA or HDPE is partially unevenly distributed due to their incompatibility. It will be in the state.

  In this case, although EVOH or PA itself is excellent in low fuel permeability, it is separated from each other as a large lump and is unevenly distributed in the HDPE matrix (provided that HDPE is a matrix), so the fuel gas is Easily escapes through the EVOH or PA masses.

This is because EVOH, PA, and HDPE are a combination of incompatible materials, so that even if they are physically mixed, they are phase-separated to form an interface with poor affinity.
As a result, this mixed material (blend material) becomes like a large EVOH or PA lump as a foreign substance and becomes weak in strength (becomes tattered), and peels off at the interface between the two. It tends to occur.

On the other hand, in the present embodiment, as an alloying material with EVOH or PA, a modified HDPE resin obtained by introducing a functional group having chemical reactivity (mainly hydrogen bond, covalent bond) with respect to the hydroxyl group of EVOH, or Since a modified HDPE resin obtained by introducing a functional group having chemical reactivity (mainly hydrogen bond, covalent bond) to the amine group of PA is used, EVOH or PA and HDPE are uniformly mixed and dispersed. Both will be in a fused state.
Thereby, both good weldability (weldability to the fuel tank 10) and low fuel permeability (barrier property) are realized.

  Thus, EVOH or PA and HDPE are uniformly mixed and dispersed to form a homogeneous phase in which they are fused with each other, because HDPE has a high affinity for EVOH or PA due to the modification by the introduction of functional groups. It depends.

  In addition, a resin alloy material obtained by alloying EVOH or PA and modified HDPE uniformly mixes and disperses to form a homogeneous phase, so that the impact resistance is enhanced in addition to the strength of the material.

Here, examples of the functional group introduced into the above-mentioned modifying group, that is, HDPE, include a carboxylic acid group, a carboxylic anhydride, an epoxy group, an acrylate group, a methacrylate group, a vinyl acetate group, and an amino group.
Further, the welding strength can be increased by increasing the ratio of HDPE, and the low fuel permeability can be improved by increasing the ratio of EVOH or PA. By adjusting the ratio in this way, it is possible to cope with both improvement in welding strength and low fuel permeability. As a ratio, EVOH or PA / modified HDPE can be 80/20 to 15/85 by volume ratio.
EVOH, PA, and modified HDPE each have an MFR (melt mass flow rate) value of 10 (g / 10 min) or less (JIS K7210), and the flowability of the resin alloy material is good when the welded joint 12 is molded. Excellent formability.

Moreover, the fact that the compatibilizing material does not need to be included in the above composition is also a factor that can improve the low fuel permeability. However, if necessary, a compatibilizing material, an inorganic filler or the like may be blended in the resin alloy material. However, if the compatibilizing material is added too much, the crystallinity of the substrate is lowered and the permeability is increased (the barrier property is lowered). Therefore, the compatibilizing material is added within a range where the required barrier performance can be ensured.
In addition to alloying modified HDPE with EVOH or PA alone, it may be alloyed with EVOH or PA using both normal HDPE and modified HDPE. Ordinary HDPE also has an MFR value of 10 (g / 10 min) or less (JIS K7210), and a resin alloy material containing this HDPE also has good flowability and excellent moldability.

  In the present embodiment, the resin alloy material may have a sea-island structure in which one of EVOH, PA, and modified HDPE is the sea and the other is the island.

FIG. 4 shows a procedure for welding the welding joint 12 shown in FIGS. 2 and 3 to the fuel tank 10.
In order to thermally weld and integrate the welding joint 12 to the fuel tank 10, as shown in FIGS. 4I and 4I, the welding joint 12 formed separately from the fuel tank 10 and the fuel tank 10 are connected. A hot plate 40 is sandwiched between them to heat the front end surface of the falling portion 26 of the welding joint 12, specifically, the welding surface 38 of the high welding layer 34 and the welding surface of the outer layer 10-1 of the fuel tank 10 here. Melt.

  4 (III), the heat plate 40 is removed, the welding surface 38 of the welding joint 12 is overlaid on the fuel tank 10, and a downward force is applied in the drawing to attach the welding joint 12 to the fuel tank 10. It is heat-welded and integrated (Fig. 4 (IV)).

FIG. 5 shows another embodiment of the present invention.
Specifically, the shape of the high welding layer 34 is different from that of the above embodiment.
Specifically, in this embodiment, the outer peripheral surface of the high weld layer 34 is a tapered surface 42 that gradually becomes smaller in diameter from the tip surface on the fuel tank 10 side upward in the drawing, that is, toward the cylindrical portion 14 side. In addition, about another part, it is the same shape as the said embodiment.

6 to 8 show the shape effect of the high weld layer 34 shown in FIG. 5 together with the molding method of the weld joint 12.
In these drawings, reference numeral 44 denotes a molding die of the welding joint 12, 46 denotes a molding cavity provided in the molding die 44, and 48 denotes a molding portion of the falling portion 36 in the welding portion 16.
Reference numeral 48-1 denotes a molding surface of the outer peripheral surface of the falling portion 26, 48-2 denotes a molding surface of the inner peripheral surface, and 48-3 denotes a molding surface of the front end surface, that is, the welding surface 38 of the falling portion 26. ing.

  FIG. 6B shows a case where the welding joint 12 shown in FIG. 2 is formed. First, a high welding layer 34 having a plate shape and a ring shape as a whole is previously formed, and this is formed into a forming cavity 46. It is set inside, specifically in the forming part 48 of the falling part 26. At this time, the molding surfaces 48-1, 48-2, and 48-3 are arranged so that the outer peripheral surface and inner peripheral surface of the high welding layer 34 and the lower surface in FIG.

However, the pre-molded high weld layer 34 is slightly smaller than the insertion position of the high weld layer 34 in the molding portion 48 so that the high weld layer 34 can be reliably inserted and set in the molding portion 48. .
Therefore, strictly speaking, in a state where the high welding layer 34 is inserted and set in the molding portion 48, a slight gap is generated between the outer peripheral surface and the molding surface 48-1.

In this state, a resin alloy material, which is a material of the welding joint 12, is injected from the lateral injection port 50 in the right direction in the figure, and this is filled into the molding cavity 46, and the high welding layer 34 and the other portions are formed. Two colors are molded together.
At this time, in the case of the high weld layer 34 having the shape shown in FIG. 2B, the pressure of the resin alloy material injected from the injection port 50 causes the high weld layer 34 to be turned up as shown in FIG. It may occur.
When such a phenomenon occurs, the high welding layer 34 is not formed at a predetermined regular position shown in FIG.

  On the other hand, in the case of the high weld layer 34 shown in FIG. 5, since the outer peripheral surface is a tapered surface 42, the resin alloy material is injected from the injection port 50 in a state where the outer peripheral surface is set in the molding portion 48. When the taper surface 42 is pushed downward by the pressure as shown in FIG. 7 (B), the high weld layer 34 set on the molding portion 48 is turned up as shown in FIG. 7 (A). Without being caused to adhere to the molding surface 48-3.

In this state, the entire weld joint 12 is molded from a resin alloy material, and at the same time, the high weld layer 34 is integrated by two-color molding.
Therefore, when the high weld layer 34 is formed in the shape shown in FIG. 5, when the weld joint 12 including the high weld layer 34 is formed by two-color molding, the high weld layer 34 is in a predetermined position and in the correct orientation and shape. This can be formed.

  According to the present embodiment as described above, a higher welding performance can be imparted to the welded portion 16 configured using a resin alloy material. When the welded joint 12 is welded to the fuel tank 10, the welded portion is welded. The welding joint 12 can be welded to the fuel tank 10 with sufficiently stable and strong welding strength regardless of the conditions.

8 and 9 show still another embodiment of the present invention.
As shown in FIG. 9, in this example, only about half of the inner peripheral side portion of the tip end portion on the fuel tank 10 side of the falling portion 26 in the welded portion 16 is used as the high weld layer 34 of the same material as described above. This is an example configured.

In the case of this embodiment, when the weld joint 12 is welded to the fuel tank 10, the inner peripheral high weld layer 34 is welded to the fuel tank 10 at the tip end portion of the falling portion 26, and the outer peripheral side portion. That is, the main portion 36 made of a resin alloy material is welded to the fuel tank 10 at the welding surface 38.
Even in this case, the high welding layer 34 can make the welding strength of the welding joint 12 to the fuel tank 10 higher than that of the resin alloy material alone.

  Further, since the resin alloy material is welded to the fuel tank 10 at the outer peripheral side portion to form a permeation-resistant wall against the permeation of fuel gas, the tip of the falling portion 26 is compared with that shown in FIGS. The low fuel permeability in the portion can be further increased.

  Since the outer peripheral side portion of the tip portion of the falling portion 26 is made of a resin alloy material having a lower fuel permeability than the high weld layer 34 of the inner peripheral side portion, even if the high weld layer 34 is used. Even if the fuel gas permeates to the outer peripheral side, the fuel gas can be permeated and blocked at the outer peripheral side portion, and the fuel gas from the inside of the fuel tank 10 is effectively prevented from leaking to the outside through the tip portion. Can do.

FIG. 10 shows a state in which the high weld layer 34 of FIG. 9B is formed in advance and is inserted and set in the forming portion 48 as an insert material.
In this state, when the welded portion 16 (that is, the entire weld joint 12) is molded with the resin alloy material, when the resin alloy material is injected from the injection port 50 in the right direction in the figure, the annular molded portion 48 is moved in the right direction from the left side in the figure. The encircling resin alloy material enters the inside of the ring-shaped high welding layer 34 by the injection pressure, and further presses and spreads the right side portion of the high welding layer 34 in the drawing away from the molding surface 48-3. And there exists a possibility that the high welding layer 34 may be integrated with the welding part 16 in a deformation | transformation state, with the resin alloy material having entered between the high welding layer 34 and the molding surface 48-3.

FIG. 11 shows a countermeasure shape of the high weld layer 34 for such a problem.
As shown in the drawing, in this state, the support portion 54 that comes into contact with the molding surface 48-1 on the outer peripheral surface in a state where the high welding layer 34 is set in the molding portion 48 has a shape protruding radially to the ring-like high welding layer 34. A plurality are provided at predetermined intervals along the circumferential direction.

  In this way, when the resin alloy material is injected from the injection port 50, the high welding layer 34 can be prevented from being deformed as shown in FIG. 10B due to the injection pressure. By using the high weld layer 34 having the shape shown, the high weld layer 34 can be well integrated with the welded portion 16 at a target position. In the molded weld joint 12, the distal end of the support portion 54 reaches the outer periphery of the falling portion 26 or the distal end portion of the falling portion 26.

In the above, only about half of the tip end portion of the falling part 26 on the inner peripheral side is constituted by the high welding layer 34, but in some cases, about half of the outer peripheral side of the falling part 36 is formed on the high welding layer 34. Or an intermediate portion between the outer peripheral portion and the inner peripheral portion can be formed by the high weld layer 34. In these cases, the same effect as described above can be obtained. be able to.
In some cases, the ring-shaped high weld layer 34 may be divided into a plurality of locations between the outer peripheral surface and the inner peripheral surface.

When the high weld layer 34 is provided on the outer peripheral side of the tip portion of the falling portion 36, the support portion 54 is projected radially toward the inner peripheral molding surface 48-3, and these are formed on the molding surface 48. -3. Here, in the molded weld joint 12, the tip of the support portion 54 reaches the inner periphery of the falling portion 26 or the tip portion of the falling portion 26.
Further, when the high weld layer 34 is partially provided at the intermediate portion between the outer peripheral side and the inner peripheral side, the support portions 54 as described above are radially formed on both the inner peripheral side and the outer peripheral side. These can be brought into contact with the molding surfaces 48-1 and 48-3, respectively. Here, in the molded welding joint 12, the tip of the support portion 54 reaches the inner periphery and the outer periphery of the falling portion 26 or the leading end portion of the falling portion 26.

  Although the embodiments of the present invention have been described in detail above, these are merely examples. For example, in the present invention, it is desirable that the entire weld joint 12 excluding the high weld layer is composed of a single resin alloy material as described above. However, in some cases, another material is integrally formed on the inner surface or outer surface of the cylindrical portion. The present invention can be configured in various forms without departing from the gist of the present invention.

It is a figure which shows the welding joint of one Embodiment of this invention in the welding state to a fuel tank. It is a figure which shows the welding joint of FIG. 1 in the state before welding. It is a perspective view of the welding joint of FIG. It is explanatory drawing of the welding process in the embodiment. It is a principal part enlarged view which shows other embodiment of this invention. It is explanatory drawing of the shaping | molding method of a welding joint. It is explanatory drawing of the advantage of embodiment of FIG. It is a figure which shows other embodiment of this invention. It is a figure which shows the state before welding of the welding joint of FIG. It is explanatory drawing of the problem in the case of shaping | molding in the embodiment. It is a figure which shows the principal part of other embodiment of this invention. It is explanatory drawing which shows the conventional connection system with respect to the fuel tank of a resin tube. It is a figure which decomposes | disassembles and shows the connection structure of FIG. 12 to each member. It is a figure which shows the structural example of a conventionally well-known welding joint. It is a figure which shows the example of the conventional welding joint different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel tank 12 Welding joint 14 Cylindrical part 16 Welding part 34 High welding layer 38 Welding surface 42 Tapered surface 44 Molding die 48 Molding part 54 Support part

Claims (7)

It has a tubular portion as a connecting portion of a tube or connector for piping and a weld portion at the base end portion, and is integrally welded to the peripheral portion of the opening portion of the resin fuel tank at the weld portion. Welding joints,
At least the welded portion is composed of a modified HDPE having an affinity with a low-permeability barrier resin alone or using a resin alloy material formed by alloying with the barrier resin together with HDPE, and in the welded portion, A high weld layer made of HDPE resin or / and modified HDPE resin with high weldability to the fuel tank is formed at the tip of the fuel tank, and the weld is made with the tip surface of the high weld layer as the weld surface. A welding joint in a fuel tank, characterized in that a portion is welded to the fuel tank. It has a tubular portion as a connecting portion of a tube or connector for piping and a weld portion at the base end portion, and is integrally welded to the peripheral portion of the opening portion of the resin fuel tank at the weld portion. Welding joints,
A resin alloy material in which at least the welded part is a modified HDPE obtained by introducing a functional group having a high affinity for the hydroxyl group of EVOH or the amine group of PA alone or together with HDPE and alloyed with EVOH or PA is used. In addition, a high weld layer made of HDPE resin or / and modified HDPE resin having high weldability to the fuel tank is formed at the tip of the weld portion on the fuel tank side. A welding joint in a fuel tank, characterized in that the welding portion is welded to the fuel tank with the front end surface of the welding layer as a welding surface.   3. The welding joint in a fuel tank according to claim 1, wherein the entire tip of the welding portion on the fuel tank side is constituted by the high welding layer over the entire circumference. 4.   In Claim 1 or 2, the outer peripheral side part or inner peripheral side part of the tip part on the fuel tank side in the welded part or an intermediate part between them is partially configured as the high welded layer over the entire circumference. The fuel is characterized in that the welded portion is welded to the fuel tank with the front end surface of the portion made of the resin alloy material of the welded portion and the front end surface of the highly welded layer as a welded surface. Weld joint in tank.   4. The fuel tank according to claim 3, wherein the outer peripheral surface of the high weld layer is a tapered surface that gradually becomes smaller in diameter as it moves away from the tip surface on the fuel tank side toward the cylindrical portion. Weld joint.   In claim 4, the high weld layer is in contact with the molding surface of the mold in a state where the high weld layer formed in advance in a mold for molding the weld joint using the resin alloy material is set. A welding joint in a fuel tank, wherein support portions for preventing deformation of the highly welded layer when the resin alloy material is injected into the mold and formed are radially provided.   The welding in a fuel tank according to any one of claims 1 to 6, wherein the welded portion and the tubular portion excluding the high welded layer are formed using a single resin alloy material. Joint.

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