JP2017095022A - Manufacturing method of fuel tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a fuel tank capable of preventing defect generation on a welding spot without thickening a layer thickness of a tank body.SOLUTION: When forming a tank body 2 made of a resin, an annular base plate 3 comprising an approximately homogenous resin material with an outside wall surface of the tank body 2 is thermally welded by heat of the tank body 2 on the outside wall surface around an opening hole 6 of the tank body 2. After forming the tank body 2, the base plate 3 is heated, and a cylindrical joint member 4 comprising approximately homogenous resin material with the base plate 3, through which a fuel passes inside, is thermally welded on the base plate 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a fuel tank.

  As a fuel tank for use in an automobile, a technique for attaching a welded part to a tank body by welding after molding the tank body is known. For example, Patent Document 1 describes that a joint portion of a fuel supply valve as a welding part is attached to an outer wall surface of a tank body by thermal welding.

JP 2006-218900 A

  However, the technique of Patent Document 1 has the following problems. When attaching a welded part to the outer wall surface of the tank body, generally the welded part of the tank body taken out from the mold is once heated by the heater 21 as shown in FIGS. 6 (a) and 6 (b). The method of welding parts is taken. The layer structure of the tank body 22 is formed at least inside the barrier layer 22C made of a material excellent in fuel impermeability, the thermoplastic resin layer 22A formed outside the barrier layer 22C, and the barrier layer 22C. The thermoplastic resin layer 22B is included, and the welded part is thermally welded to the outer thermoplastic resin layer 22A.

  Here, if the layer thickness of the tank body 22 is thin, when the heater 21 is pressed against the tank body 22, the wall surface around the opening 23 of the tank body 22 is the tank wall as shown in FIG. There is a risk of bending inward and inadequate heating, leading to poor welding. Further, when the thermoplastic resin layer 22A is thin, as shown in FIG. 6C, the barrier layer 22C may be melted. If the thickness of the thermoplastic resin layer 22A is increased, the rigidity around the opening hole 23 is increased, so that bending can be suppressed and the melting of the barrier layer 22C can be reduced. However, if the thickness of the thermoplastic resin layer 22A is increased, it extends over the entire tank body 22 and thus increases the weight of the tank body 22.

  The present invention was created to solve such problems, and an object of the present invention is to provide a method of manufacturing a fuel tank that can prevent the occurrence of defects in welded portions without increasing the layer thickness of the tank body. Yes.

  In order to solve the above-described problems, the present invention provides an annular base plate made of a resin material substantially the same quality as the outer wall surface of the tank main body on the outer wall surface around the opening hole of the tank main body when the resin tank main body is molded. After the tank body is molded by heat welding with the heat of the tank body, the base plate is heated, and then a cylindrical welded part made of a resin material substantially the same as the base plate and through which fuel passes is attached to the base plate. It is characterized by heat welding.

  According to the present invention, the rigidity around the opening hole of the tank body is increased by the intervention of the base plate. Thereby, when heating a baseplate with a heater, the bending around the opening hole of a tank main body at the time of pressing a heater against a baseplate can be suppressed. The distance between the heater and the barrier layer is increased by the presence of the base plate, and the barrier layer is not melted by the heater. In order to secure the rigidity around the opening hole, it is only necessary to provide a small and light weight base plate. Therefore, it is not necessary to increase the layer thickness of the tank body, and the problem of an increase in the weight of the tank body does not occur. Further, since the outer wall surface of the tank body, the base plate, and the welded parts are made of substantially the same resin material, the welded parts can be easily attached to the tank body using thermal welding.

  Further, according to the present invention, a plurality of convex portions and groove portions are formed along the ring direction on one surface of both surfaces of the base plate that are thermally welded to the tank body, and the groove portion faces the other surface. An air escape hole penetrating therethrough is formed.

  According to the present invention, it is possible to increase the welding area between the tank main body and the base plate, and to release the air remaining in the groove portion to the outside from the air escape hole, thereby improving the adhesion between the tank main body and the base plate.

  Further, the present invention is characterized in that the air escape hole is closed by the welding component or faces the inside of the welding component.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the heat welding part of a baseplate and a tank main body is exposed to external air through an air escape hole.

  Further, the present invention is characterized in that an air escape notch is formed in the convex portion so as to connect groove bottom surfaces of adjacent groove portions with the convex portion interposed therebetween.

  According to the present invention, the air remaining in the groove can be discharged to the outside from the outer peripheral edge or the inner peripheral edge of the base plate through the air escape notch, and the adhesion between the tank body and the base plate can be improved.

  Further, according to the present invention, the air escape hole is formed in a groove portion close to an inner diameter, and the groove of the groove portion adjacent to the convex portion between the groove portions near the outer diameter where the air escape hole is not formed is sandwiched between the protrusions. An air escape notch that connects the bottom surfaces is formed.

  According to the present invention, it is possible to prevent the heat welded portion between the base plate and the tank body from touching the outside air through the air escape hole and the air escape notch with a simple structure.

  Further, in the present invention, the tank main body is a molded product by a blow molding or vacuum molding mold, the base plate is held by the molding die, and the tank main body is molded by the molding die when the tank main body is molded. The held base plate is thermally welded to the tank body.

  According to the present invention, since the base plate can be attached at the time of forming the parison of the tank body, it is possible to suppress an increase in the manufacturing cycle time of the fuel tank.

  According to the present invention, it is possible to prevent the occurrence of defects at the weld location without increasing the layer thickness of the tank body.

It is sectional drawing of the principal part of the fuel tank concerning this invention, (a) shows the state before attaching a joint member, (b) shows the state which attached the joint member. It is a top view of a base plate. It is an external appearance perspective view of a base plate. It is a side view of a fuel tank in the state where a filler pipe was attached. It is sectional drawing when a heater is pressed on a base plate. In the conventional fuel tank, (a) is a state before the heater is pressed against the welding location, (b) is a state where the heater is pressed against the welding location, and (c) is a sectional view showing a state where the barrier layer is melted.

  As shown in FIG. 4, the fuel tank 1 is thermally welded to the resin tank body 2, a resin base plate 3 whose one surface is thermally welded to the outer wall surface of the tank body 2, and the other surface of the base plate 3. And a resin joint member (welded part) 4.

  The fuel tank 1 of the present embodiment is a fuel tank mounted on an automobile. The layer structure of the tank body 2 includes at least a barrier layer 2C, a thermoplastic resin layer 2A formed outside the barrier layer 2C, and a thermoplastic resin layer 2B formed inside the barrier layer 2C. . The barrier layer 2C is formed of a material excellent in fuel impermeability, for example, EVOH (ethylene-vinyl alcohol copolymer). The thermoplastic resin layers 2A and 2B are made of, for example, HDPE (high density polyethylene).

  The joint member 4 is a cylindrical member for attaching the filler pipe 5 for refueling to the tank body 2, one end side is thermally welded to the base plate 3, and the other end side is connected to the end of the filler pipe 5. Yes. The joint member 4 is formed of a thermoplastic resin that is substantially the same quality as the base plate 3 so that it can be thermally welded to the base plate 3.

  Referring to FIGS. 1 to 3, base plate 3 is an annular plate-like member, and one surface is thermally welded to an outer wall surface around opening hole 6 formed in tank body 2. The base plate 3 is formed of a thermoplastic resin that is substantially the same quality as the thermoplastic resin layer 2A so that it can be thermally welded to the thermoplastic resin layer 2A outside the tank body 2. A plurality of convex portions 7 and groove portions 8 are formed on one surface of the base plate 3 along the ring direction in order to increase the welding area with the tank body 2. The height of the convex portion 7 is a height that does not affect the barrier layer 2C. In the present embodiment, a total of four convex portions 7 and four groove portions 8 are alternately formed in a layout in which the convex portions 7 are positioned on the inner peripheral edge of the base plate 3 and the groove portions 8 are positioned on the outer peripheral edge. Here, in order from the inner diameter side, 7A, 7B, 7C, and 7D are assigned to the convex portion 7, and 8A, 8B, 8C, and 8D are assigned to the groove portion 8.

  In the groove portion 8, an air escape hole 9 having a circular cross section penetrating toward the other surface is formed. The air escape hole 9 has a function of escaping air that may remain in the groove 8 when the base plate 3 is pressed against the tank body 2 during heat welding. The air escape holes 9 are formed in the groove portions 8A and 8B that are grooves closer to the inner diameter, and are not formed in the groove portions 8C and 8D that are grooves closer to the outer diameter. A plurality of air escape holes 9 are formed at intervals in the circumferential direction in the groove portions 8A and 8B. FIG. 2 shows a case where four air escape holes 9 are formed at intervals of 90 degrees in the groove portions 8A and 8B. The air escape hole 9 of the groove 8A and the air escape hole 9 of the groove 8B are formed so that the phases are shifted by 90 degrees. As shown in FIG. 1B, each air escape hole 9 of the groove portion 8 </ b> B is closed by one end of the joint member 4, and each air escape hole 9 of the groove portion 8 </ b> A faces the inside of the joint member 4.

  An air escape notch 10 is formed in the convex portion 7 so that the groove bottom surfaces of adjacent groove portions 8 sandwiching the convex portion 7 are connected to each other. In the present embodiment, the air escape notch 10 is formed in the convex portion 7D between the groove portions 8C and 8D near the outer diameter where the air escape hole 9 is not formed. The air escape notch 10 has a function of allowing air that can remain in the groove 8C to escape to the outer diameter side through the groove 8D when the base plate 3 is pressed against the tank body 2 during heat welding. A plurality of air escape notches 10 are formed at intervals in the circumferential direction in the convex portion 7D. FIG. 2 shows a case where four air escape notches 10 are formed at intervals of 90 degrees.

"Attaching method of base plate 3"
When the tank body 2 is molded by a blow mold (not shown), the base plate 3 is held on the molding surface of the mold. Thus, when the parison constituting the tank body 2 is transferred to the molding surface, the base plate 3 is pressed against the outer wall surface of the parison (tank body 2), that is, the thermoplastic resin layer 2A, and the heat of the mold and the parison (tank body) 2) heat welding. Large welding strength is ensured by the large welding area by the convex part 7 and the groove part 8. If air remains in the grooves 8A and 8B, it is discharged to the outside from the air escape hole 9, and if air remains in the groove 8C, it is discharged to the outside from the air escape notch 10.

"Attaching method of joint member 4"
Next, the tank body 2 is taken out from the mold, and the joint member 4 is attached after the opening hole 6 is formed. Since the tank body 2 taken out from the mold is cooled by water and / or air, the base plate 3 is heated by pressing the heater 21 against the other surface side of the base plate 3 as shown in FIG. At this time, since the rigidity of the tank body 2 around the opening hole 6 is increased by the presence of the base plate 3, the tank body 2 around the opening hole 6 remains inside the tank even when strongly pressed against the heater 21. It will not bend greatly. Accordingly, the other surface of the base plate 3 is pressed against the heater 21 in a normal posture, and heating unevenness does not occur. Since the distance between the heater 21 and the barrier layer 2C is increased by the presence of the base plate 3, the barrier layer 2C is not melted by the heater 21.

  Then, the heater 21 is retracted, and the joint member 4 is concentrically pressed against the heated base plate 3 and thermally welded. As described above, since the rigidity of the tank body 2 around the opening hole 6 is increased by the presence of the base plate 3, even if the joint member 4 is strongly pressed against the base plate 3, the tank around the opening hole 6. The main body 2 does not bend greatly inside the tank. Therefore, the joint member 4 is pressed against the base plate 3 in a normal posture and thermally welded. As shown in FIG. 1B, the air escape hole 9 of the groove 8B is closed by the joint member 4, and the air escape hole 9 of the groove 8A faces the inside of the joint member 4 which is a passage space for fuel. .

  As described above, when molding the resin tank body 2, the annular base plate 3 made of a resin material substantially the same quality as the outer wall surface of the tank body 2 is placed on the outer wall surface around the opening hole 6 of the tank body 2. After the tank body 2 is molded, the base plate 3 is heated, and a cylindrical welded part (joint member 4) that is made of a resin material substantially the same as the base plate 3 and through which the fuel passes is formed into the base plate. 3, it is only necessary to provide a small and low-weight base plate 3 to secure the rigidity around the opening hole 6, so that it is not necessary to increase the layer thickness of the tank body 2, The problem of weight increase of the main body 2 does not occur. Since the outer wall surface of the tank body 2, the base plate 3, and the welded part (joint member 4) are made of substantially the same resin material, the welded part (joint member 4) can be easily attached to the tank body 2 using thermal welding. Can be attached.

  By forming a plurality of convex portions 7 and groove portions 8 along the ring direction on one surface of both surfaces of the base plate 3 that are heat-welded to the tank body 2, the welding area between the tank body 2 and the base plate 3 can be increased. . If the air escape hole 9 penetrating toward the other surface is formed in the groove portion 8, the air remaining in the groove portion 8 is released to the outside from the air escape hole 9, and the adhesion between the tank body 2 and the base plate 3 is released. Can be increased.

  If the air escape hole 9 is blocked by a welded part (joint member 4) or faces the inside of the welded part (joint member 4), the heat welded portion between the base plate 3 and the tank body 2 passes through the air escape hole 9. It can be prevented from being constantly exposed to the open air.

  If an air escape notch 10 is formed on the convex portion 7 so that the groove bottom surfaces of the adjacent groove portions 8 sandwiching the convex portion 7 are formed, the air remaining in the groove portion 8 passes through the air escape notch 10 and the base plate 3. The outer peripheral edge or the inner peripheral edge can be discharged to the outside, and the adhesion between the tank body 2 and the base plate 3 can be enhanced.

  In particular, as in the present embodiment, the air escape holes 9 are formed in the grooves 8A and 8B near the inner diameter, and the convex portions 7D between the grooves 8C and 8D near the outer diameter where the air escape holes 9 are not formed If the air escape notch 10 that connects the groove bottom surfaces of the adjacent groove portions 8C and 8D with the convex portion 7D interposed therebetween is formed, the following operations and effects can be achieved. As described above, the air escape hole 9 is covered with the welded part (joint member 4) or is exposed to the inside of the welded part (joint member 4), so that the heat welded portion between the base plate 3 and the tank body 2 is obtained. Can be prevented from being always exposed to the outside air through the air escape hole 9. On the other hand, regarding the air escape notch 10, the air in the groove 8 </ b> C escapes from the air escape notch 10 to the groove 8 </ b> D and is discharged to the outside from the outer peripheral edge of the base plate 3 at the time of heat welding. Since the air escape notch 10 is not exposed to the outside after the thermal welding, it is not necessary to take measures such as closing the welded part (joint member 4) like the air escape hole 9. Thus, according to the present invention, at the time of heat welding, all the air that can accumulate in the grooves 8A to 8D can be discharged to the outside from the air escape hole 9 and the air escape notch 10, and after the heat welding, the base plate 3 It is possible to easily prevent the heat welded portion between the tank body 2 and the tank body 2 from touching the outside air through the air escape hole 9 and the air escape notch 10.

  Further, when the tank body 2 is a molded product using a blow molding or vacuum molding mold, the base plate 3 is held by the molding die, and when the tank body 2 is molded by the molding die, the base plate 3 held by the molding die is tanked. If it is set as the manufacturing method heat-welded to the outer wall face of the main body 2, since the base plate 3 can be attached at the time of shaping | molding of the parison of the tank main body 2, it can suppress that the manufacturing cycle time of the fuel tank 1 increases.

  The preferred embodiment of the present invention has been described above. The welded part is not limited to the joint member 4 that connects the filler pipe 5, and may be a casing of various valves such as a fuel cut valve.

1 Fuel tank 2 Tank body 3 Base plate 4 Joint member (welded part)
6 Opening hole 7 Convex 8 Groove 9 Air escape hole 10 Air escape notch

Claims (6)

When molding the resin tank body, an annular base plate made of a resin material substantially the same as the outer wall surface of the tank body is thermally welded to the outer wall surface around the opening hole of the tank body by the heat of the tank body,
After forming the tank body, the base plate is heated, and a tubular welded part made of a resin material substantially the same as the base plate and through which fuel passes is thermally welded to the base plate. Manufacturing method. On one surface of the base plate that is heat-welded to the tank body, a plurality of convex portions and groove portions are formed along the ring direction.
The method for manufacturing a fuel tank according to claim 1, wherein an air escape hole penetrating toward the other surface is formed in the groove portion.   The method of manufacturing a fuel tank according to claim 2, wherein the air escape hole is closed by the welded part or faces the inside of the welded part.   The method for manufacturing a fuel tank according to claim 2, wherein an air escape notch is formed in the convex portion so as to connect groove bottom surfaces of adjacent groove portions with the convex portion interposed therebetween. The air escape hole is formed in a groove near the inner diameter,
An air escape notch is formed in the convex portion between the groove portions near the outer diameter where the air escape hole is not formed so as to connect the groove bottom surfaces of adjacent groove portions sandwiching the convex portion. The method for manufacturing a fuel tank according to claim 3. The tank body is a molded product by a blow molding or vacuum forming mold,
Holding the base plate on the mold,
6. The fuel tank according to claim 1, wherein the base plate held by the molding die is thermally welded to the tank main body when the tank main body is molded by the molding die. 7. Manufacturing method.

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