JP2010510136A - Conduit line arrangement structure in plastic container - Google Patents

Abstract

  Regarding the plastic hollow body by extrusion blow molding, particularly the fuel tank (1), one or more conduit lines are laid in the hollow body so as not to move. The hollow body according to the present invention is characterized in that the conduit line is joined to the inner wall of the hollow body over at least a part of the length range by bonding of materials.

Description

  The present invention relates to a conduit line arrangement structure in a plastic container.

  It is known to fix conduit lines, which are laid so as not to move inside the plastic container, to the inner wall of the plastic container by means of clips. It is also known that a snap-type latch for fixing the conduit line is integrally provided on the inner wall of the container.

  In many cases, plastic containers, ie plastic hollow bodies, are produced by extrusion blow molding. In extrusion blow molding, a tubular parison (preform) extruded from a head is expanded by pressurized air from the inside in a cavity formed in a split mold. In particular, when the hollow body to be molded constitutes an industrial part having a complicated function, it is necessary to arrange accessory functional parts connected by conduit lines such as pipes and electric wires inside the hollow body. In addition, conduit lines for introducing or introducing fluid are often arranged in the hollow body. As these conduit lines, for example, in a plastic fuel tank for automobiles, an air pipe, an intake pipe, a fuel supply pipe, and various electric cables are laid inside.

  In most cases, the laying position of these conduit lines is determined by the position of the functional component in the hollow body. The laid conduit line can be fixed by, for example, a direct fixing method by fixing functional parts in the hollow body. In the production of a fuel tank, it is known that several functional parts such as valves are fitted and fixed in openings opened in the walls of a hollow body. Such mounting locations require expensive and complex seals. Moreover, the operation | work which mounts a conduit line in a predetermined position is generally performed manually through the center opening provided in the hollow body.

  In the production of a hollow body consisting of multiple split shells, it is relatively easy to install the conduit line in the hollow body. This is because the conduit line is positioned and fixed before the split shell is closed in the final assembly operation. Limited to when possible.

  As mentioned above, it is known to fix the conduit line at various positions within the hollow body by means of retaining clips provided within the hollow body. It is also possible to provide a snap-type latching device in the form of a slight undercut on the inner wall of the hollow body, and it is also possible to press fit a conduit line into this latching device. The operation of installing the conduit line at a predetermined position is not limited to the process of forming the hollow body, and can be manually performed through the maintenance opening provided in the hollow body or the large-diameter removal opening even after the hollow body has been formed. It can be carried out.

  However, the installation of the conduit line by such a method often causes trouble. In addition, when using a clip or a latch, there is always a risk that the conduit line will eventually loosen depending on the use of the hollow body. This must be avoided by all means, especially in the case of fuel tanks, since the functional parts operating in the tank cause essentially unwanted vibrations and noise.

  The object of the present invention is therefore to avoid the disadvantages of the prior art described above.

  According to the present invention, the object of the present invention is to provide a hollow body made of plastic material in which one or more conduit lines do not move. This can be solved by joining the inner wall by bonding of materials.

  The hollow body according to a preferred embodiment of the present invention has the form of an extrusion blow molded container, and the conduit line laid in the container is manufactured by a separate operation from the hollow body extrusion blow molding. Consists of things.

  The hollow body in this case may be a fuel tank for automobiles by extrusion blow molding.

  According to another preferred embodiment of the invention, the conduit line is welded to the inner wall of the hollow body. In this case, the welding may be performed over the entire length of the conduit line in the hollow body, but it is necessary to weld over at least a part of the length region.

  According to a particularly preferred embodiment of the invention, the conduit line has a multilayer wall structure, the outermost layer of the multilayer wall being a tube made of a plastic material compatible with the inner wall of the hollow body, The plastic material of the outer layer and the plastic material of the inner wall of the hollow body can be welded together.

  When a fuel tank by extrusion blow molding is constituted by such a hollow body, the tank wall is preferably in the form of a coextrusion plastic multilayer wall including a hydrocarbon barrier layer made of EVOH (ethylene vinyl alcohol). In this case, the outermost layer of the tank wall is generally a carbon black filled polyethylene tube, and the inner wall surface of the tank is generally a high purity polyethylene layer. The hydrocarbon barrier layer is a sandwich tube with both sides sandwiched by adhesive layers. One or more recycled plastic material layers may be interposed between the outermost layer of the tank wall and the barrier layer or its adhesive layer.

  As described above, when a fuel tank having a multilayer wall structure is manufactured by extrusion blow molding, it is necessary to avoid the formation of gaps and holes in the tank wall as much as possible. The need for doing so has been known for a long time in the prior art. Normally, as with valves and valve bodies, fuel supply lines and conduits are generally not made of polyolefin or polyethylene, because they expand or deform in the presence of fuel hydrocarbons and are durable. This is to avoid the inability to maintain sex. Therefore, it has been conventionally difficult to weld such an accessory made of a material different from the tank wall when manufacturing the fuel tank to the tank wall.

  According to the present invention, conduit lines are coextruded into a multilayer wall structure, and the outermost layer of the multilayer wall is made of a material compatible with the inner wall of the hollow body so that they can be welded to each other. For example, the inner layer in the multi-layer wall structure of the conduit line may be a core layer made of a plastic material highly resistant to hydrocarbons, and the outermost layer covering the outer periphery may be a high-purity polyethylene layer compatible with the inner wall surface of the tank. preferable. Such conduit lines can be formed into concentric multilayer wall structures using coaxial coextrusion heads. Of course, the outermost layer in this case may be constituted exclusively as a covering layer that functions to fix the conduit line to the inner wall of the hollow body by welding. In addition, the conduit line may have a structure in which the outermost layer has a coating layer that is compatible with the inner wall of the hollow body only in a part of the length region corresponding to the fixed portion with respect to the inner wall of the hollow body, although not necessarily over the entire length. Good. The covering layer in this case functions exclusively as a welding additive or welding auxiliary member for the inner wall of the hollow body. Further, the outermost covering layer may be configured as an outer sheath that encloses a bundle of a plurality of conduits or cables.

  The outermost layer or covering layer and the inner layer or core layer of the conduit line need not be laminated with the materials bonded together. If a laminated structure with mutual bonding between materials is desired, if the plastic material of each layer of the laminated structure does not have adhesiveness to each other, the required interlayer bonding can be achieved by interposing an adhesive layer between them. A multilayer wall structure having strength can be obtained.

  The present invention also provides a method of manufacturing a hollow body made of plastic material that is laid such that one or more conduit lines do not move therein. In this production method, a hollow body is formed by extrusion blow molding, and a conduit line is extruded by a separate operation, and the conduit line is extended over at least a part of the length region at the time of molding of the hollow body or immediately after molding. And welding to the inner wall of the hollow body.

  The conduit line is placed on the inner wall of the hollow body in advance, for example, together with the functional parts mounted on the hollow body wall by the movable holder for placing parts while the hollow body is expanded in the blow mold. Also good. In this case, it is possible to surround the outer periphery of the conduit line connected to the functional part in the molding process of the hollow body with the softened blow molded plastic material.

  Alternatively, for example, the hollow body can be manufactured by a multistage extrusion blow molding process that effectively uses a three-part blow mold having two outer molds and one intermediate mold. In this case, the belt-shaped preform is extruded between the outer molds on both sides of the intermediate mold, and the mold is closed. Both preforms are each pressed against the inner wall of the outer mold that defines the inner surface of the mold cavity, as is well known, either negative pressure suction on the inner wall of the outer mold or the intermediate mold, as is well known. This is done by a differential pressure method by either increasing the gas pressure inside the mold. A plurality of movable holders for component placement are arranged inside the intermediate mold, and these holders are pressed against the inner wall side of the preform that is still plastic in the mold with the conduit lines and functional parts closed. This allows the conduit lines and functional parts to be welded to the inner wall of the hollow body before the blow molding process is complete.

  Next, when the intermediate mold is retracted from between the two outer molds, the two outer molds are closed close to each other, and the two half shells molded inside each are welded together at the peripheral portion to form a closed hollow body Is formed.

  It is also possible to manufacture a hollow container from a partial shell by deep drawing injection molding. In this case, for example, the conduit line can be inserted through the opening of the molded partial shell and the conduit line can be secured to the inner wall of the shell by a suitable welding process.

  Although the above description mainly describes one conduit line, it is needless to say that a case where a plurality of conduit lines are arranged is also included.

  The features and advantages of the present invention will be described in detail with reference to the illustrated embodiment as follows.

1 shows a schematic cross-sectional view of a hollow body according to the invention in the form of an extrusion blow molded fuel tank. It is a detailed enlarged view of the II part of FIG. It is the II-III sectional view taken on the line of FIG. It is a detailed enlarged view of the IV part of FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. 6 is a cross-sectional view illustrating another embodiment of a conduit line arrangement according to the present invention. FIG. 6 is a cross-sectional view illustrating yet another embodiment of a conduit line arrangement according to the present invention. FIG. 6 is a cross-sectional view illustrating yet another embodiment of a conduit line arrangement according to the present invention with a core layer surrounding a plurality of lines within a covering layer. FIG. 6 is a cross-sectional view illustrating yet another embodiment of a conduit line arrangement according to the present invention.

  FIG. 1 is a schematic cross-sectional view of an automotive fuel tank 1 that is extrusion blow molded from a thermoplastic material. The fuel tank of the illustrated example is manufactured by a multistage extrusion blow molding process using a three-part blow molding die composed of two outer molds and one intermediate mold. In this molding process, two belt-shaped preforms are extruded one by one between the outer mold and the intermediate mold, and after closing each outer mold at both end faces of the intermediate mold, It is formed into a cavity inner surface shape by being pressed from the inside of the intermediate mold and pressed against the inner surface of each outer mold that defines each half of the mold cavity.

  The fuel tank 1 is a co-extrusion blow-molded article having a six-layered multilayer wall structure made of a thermoplastic material, and this multilayer wall structure is formed from a recycled plastic material inward from the outermost carbon black-filled polyethylene layer. A layer, a first adhesive layer, an EVOH layer, a second adhesive layer, and an innermost high-purity polyethylene (virgin PE) layer.

  Arranged inside the fuel tank 1 are various functional parts necessary for the operation of the automobile. These functional parts include a surge pod 2 containing a fuel supply pump (not shown) and a fuel take-out conduit line 3 leading to the outside of the fuel tank 1. Similar to a normal fuel tank, an opening for refueling and various vent openings connected to the vent pipe line are also provided (not shown). The vent pipe line includes a vent pipe line when the engine is operated and a vent pipe line when refueling, and these can be selectively cut off by corresponding valves. These valves are known, for example, as a rollover valve (rollover safety valve) and an oil supply ventilation valve. The refueling vent valve is used to securely close the refueling vent line when the fuel replenished in the fuel tank reaches a predetermined full tank level. When the oil pressure rises, the oil supply gun shut-off valve is responsive to automatically shut off the oil supply.

  In the illustrated embodiment, these vent lines and vents are not shown to avoid complication and only the fuel extraction conduit line 3 to the engine is shown. An example of a conduit line is an electric cable.

  As already mentioned in the background section of this specification, various techniques are known for securing conduit lines to the inner wall of a fuel tank. In fact, the most widespread method is a fixing method using a holding clip. In known techniques, the retaining clips are usually fastened to separate base members, which are further fastened to separate functional parts or notch openings in the fuel tank wall.

  On the other hand, according to the present invention, the conduit line is welded to the inner wall 4 of the fuel tank 1 over a part of its length region or entirely.

  The embodiment shown in FIG. 1 shows two forms of fixing the fuel removal conduit line 3 in one view. First, the first embodiment will be described with reference to FIG. 2 (detail of section II in FIG. 1). The fuel take-out conduit line 3 in the embodiment shown in FIG. 2 is a tube coextruded into a multilayer wall structure over the entire length. The fuel take-out conduit line 3 has a two-layer wall structure including an outer sheath layer (outermost layer) 5 and a core tube (inner layer) 6, and the outer sheath layer 5 and the core tube 6. Are not necessarily bonded to each other by bonding of materials. In the illustrated embodiment, the sheath 5 is made of high-purity PE, whereas the core tube 6 can be made of any plastic material, but the material used is a plastic that does not swell and deform in the presence of hydrocarbons. A material is preferred. The outer sheath 5 made of high-purity PE is compatible with the inner wall 4 of the fuel tank 1 in terms of weldability, because the inner wall 4 of the fuel tank 1 is also composed of a high-purity polyethylene layer as described above. Because. If the inner wall of the fuel tank is made of another material, it goes without saying that the sheath of the conduit line must also be made of a material that is weldable with the inner wall of the fuel tank.

  The conduit line in the embodiment shown in FIGS. 2 and 3 is in the form of a fuel take-off conduit line 3 and is thus constituted by a tube having a hollow space for the passage of fuel inside.

  The fuel take-out conduit line 3 shown in FIGS. 4 and 5 is also composed of the same tube, but in this case, the fuel take-out conduit line has a partial cuff-like covering which covers only a part of the length region. The short jacket tube 7 is different. The short jacket tube 7 is a polyethylene-coated tube, and this polyethylene-coated tube is made of a material that can be welded to the inner wall 4 of the fuel tank 1, and is similar to the jacket sheath 5 shown in FIGS. It is joined to the inner wall 4 of the tank 1 by a linear welded portion over its entire length. In order to prevent the short jacket tube 7 from being displaced on the conduit line 3 when it is installed in the fuel tank, the inner diameter may be set so that the short jacket tube 7 is in close contact with the outer periphery of the conduit line 3. Alternatively, the short jacket tube may be fixed to the conduit line 3 with an adhesive.

  FIG. 6 shows a conduit line arrangement according to still another embodiment of the present invention, in which two core tubes 6 are covered by a single common outer sheath 5. The outer sheath 5 is welded to the inner wall 4 of the fuel tank 1 in the same manner as in the embodiment shown in FIGS.

  The embodiment shown in FIG. 7 is an example in which an enlarged base portion 8 is provided in an outer sheath so as to ensure a relatively large joining area with respect to the inner wall 4 of the fuel tank 1. The surface is asymmetrical.

  The embodiment shown in FIG. 8 is an example in which the core tube 6 of the conduit line incorporates the cable bundle 9. The cable bundle 9 may be a plurality of fuel conduit tubes, or may be a plurality of covered wires as shown. Reference numeral 10 denotes a filler filled around the cable bundle 9 in order to fix the position of each tube or covered electric wire in the core tube 6.

  Finally, FIG. 9 shows a conduit line arrangement structure according to still another embodiment of the present invention. The core tube 6 constituting the conduit line in this case has an adhesive strip 11 on one side of the outer peripheral surface thereof. It is attached. The adhesive strip 11 can be made of, for example, a polyolefin-based plastic that is a material that can be welded to the inner wall 4 of the fuel tank. All of the adhesive strip 11, the sheath 5 and the short sheath tube 7 are optimized for their heat capacity required for welding to the inner wall of the fuel tank by appropriately selecting their material properties and thickness dimensions. Can do. In the conduit line arrangement structure according to the present invention, it is important to be able to weld the conduit line to the wall surface of the hollow body at the initial stage of the manufacturing process of the hollow body such as a fuel tank. Is preferably configured to have as little heat capacity as possible.

  As described above, the case where the present invention is applied to the fuel tank has been described. However, the present invention is not limited to the fuel tank, and can be widely applied to other extrusion blow molded hollow bodies. Needless to say.

1: Fuel tank 2: Surge pod 3: Fuel extraction conduit line 4: Tank inner wall 5: Outer sheath 6: Core tube 7: Short outer tube 8: Expanded base 9: Cable bundle 10: Filler 11: Adhesive band Fragment

Claims (6)

  A hollow body made of a plastic material, in which one or more conduit lines are laid so as not to move, the conduit lines extending at least partially over the inner wall of the hollow body A hollow body characterized by being joined by bonding of materials.   2. The container according to claim 1, wherein the conduit line laid in the container has a form of an extrusion blow molded container and is manufactured by a separate operation from the extrusion blow molding. Hollow body.   The hollow body according to claim 1, wherein the conduit line is welded to an inner wall of the hollow body.   The conduit line has a multilayer wall structure, and the outermost layer of the multilayer wall is made of a plastic material compatible with the inner wall of the hollow body, and the plastic material of the outermost layer of the conduit line and the plastic material of the inner wall of the hollow body are mutually connected. The hollow body according to any one of claims 1 to 3, wherein the hollow body is weldable.   The said conduit line is coextruded by the multilayer wall structure, The outermost layer comprises the outer sheath which can be welded to the inner wall of a hollow body, The one of Claims 1-4 characterized by the above-mentioned. Hollow body.   When producing a hollow body made of plastic material in which one or more conduit lines are prevented from moving, the hollow body is formed by extrusion blow molding, and the conduit line is extruded by a separate operation. A method for producing a hollow body, characterized in that a conduit line is welded to the inner wall of the hollow body during or immediately after molding the hollow body over at least a part of the length region.

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