JP2011093349A - Resinous fuel tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resinous fuel tank capable of decreasing weight without increasing cost. <P>SOLUTION: In the resinous fuel tank 100 molded by blow molding and having a hollow shape wherein an upper arm 51 and a lower arm 52 are assembled, an inner surface and an outer surface of at least a part of the upper arm 51 and the lower arm 52 are formed by superimposing a plurality of pyramidal parts 77 equipped with a plurality of pyramidal surfaces. At least one of the plurality of the pyramidal surfaces is an isosceles triangle. One of lines connecting each vertex on a bottom surface of the pyramidal part 77 and a top portion of the pyramid part 77 is formed in a first direction A along a cylindrical center portion 79 of the upper arm 51 and the lower arm 52 or a second direction B orthogonal to the first direction A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin fuel tank having a hollow shape in which an upper collar part and a lower collar part are formed by blow molding.

  In recent years, the weight of vehicles has been reduced for the purpose of reducing fuel consumption. As one of such weight reduction methods, the fuel tank has been changed from a metal one to a resin one. On the other hand, since a flammable substance such as gasoline is stored in the fuel tank, it is necessary to have a structure that does not break during a vehicle collision. Various shapes have been studied in order to prevent the fuel tank from being damaged even in such a vehicle collision (for example, Patent Document 1).

  The blow molded resin container described in Patent Document 1 is used as a gasoline tank for automobiles, and is formed by blow molding using a resin. In this blow molded resin container, a large concave or convex deformed portion is formed on the container surface in order to absorb the impact force applied from the outside.

Japanese Utility Model Publication No. 57-159614

  In the blow molded resin container described in Patent Document 1, since the large concave or convex deformed portion described above is formed, the weight of the fuel tank is increased accordingly, and the cost of the product is increased. turn into.

  In view of the above problems, an object of the present invention is to provide a resin fuel tank capable of appropriately absorbing the impact force applied from the outside without increasing the cost or increasing the weight.

  A feature of the resin fuel tank according to the first invention for achieving the above object is a hollow shape formed by blow molding, in which an upper collar part and a lower collar part are combined, and has a plurality of pyramidal surfaces. A plurality of the pyramid portions are connected to form at least part of the inner and outer surfaces of the upper collar portion and the lower collar portion, at least one of the plurality of pyramid surfaces is an isosceles triangle, and each of the bottom surfaces of the pyramid portion One of the lines connecting the apex and the top of the pyramid portion is along the first direction along the cylindrical central part of the upper collar part and the lower collar part, or along a second direction orthogonal to the first direction. It is in the point that is formed.

  According to the configuration of the first aspect of the invention, the displacement due to the change in the internal pressure based on the temperature change and the displacement due to the load received from the outside can be distributed to the plurality of pyramid portions, so that the displacement is concentrated in one part. Can be eliminated. Therefore, it becomes possible to make the structure hard to break. Further, since the displacement as described above is distributed to a plurality of pyramid portions, the plate thickness can be reduced. Therefore, since the amount of resin used can be reduced, the weight can be reduced without increasing the material cost.

  The resin fuel tank according to the second invention is characterized in that the pyramid portion is a quadrangular pyramid having four isosceles triangles as pyramid surfaces.

  According to the structure of the said 2nd invention, the load from both the 1st direction and the 2nd direction can be absorbed. Therefore, even if the vehicle including the resin fuel tank has a collision from the front, a collision from the rear, or a collision from the side, the impact can be absorbed.

  The resin fuel tank according to a third aspect of the present invention is characterized in that the pyramid portion is formed over substantially the entire circumference of one of the first and second directions of the upper flange portion and the lower flange portion. It exists in the point currently formed in the at least center part of the other of the said 1st direction and the said 2nd direction of a collar part and the said lower collar part.

  According to the structure of the said 3rd invention, it becomes possible to absorb a load in the center part of the resin fuel tank. Therefore, when the resin fuel tank is disposed along the front-rear direction of the vehicle, the load related to the collision from the front-rear direction of the vehicle can be absorbed particularly effectively, and the resin fuel tank is disposed along the left-right direction of the vehicle. In the case of being arranged, it is possible to particularly effectively absorb the load related to the collision from the side surface direction of the vehicle.

  The resin fuel tank according to a fourth aspect of the present invention is characterized in that the second in the center of the upper collar and the lower collar in the first direction along the cylindrical center of the upper collar and the lower collar. The inner surface of the cross section in the direction is connected to the connecting portion of the upper collar part and the lower collar part and extends to the center side of the upper collar part and the lower collar part, and a pair of firsts having a predetermined radius An arc portion, and a second arc portion having a radius larger than the predetermined radius and connected across the pair of first arc portions, the upper collar portion in the second direction, The inner surface of the cross section in the first direction at the center of the lower collar is connected to the connecting portion of the upper collar and the lower collar and extends to the center side of the upper collar and the lower collar. A pair of third arc portions and a connection portion connected across the pair of third arc portions are formed. It lies in the fact are.

  According to the fourth aspect of the present invention, when the fuel stored in the resin fuel tank volatilizes and the pressure increases, the increased pressure can be uniformly applied to the inner wall of the resin fuel tank. Stress is less concentrated. For this reason, it is possible to reduce the overall plate thickness accordingly. In addition, since the amount of resin used can be reduced, the cost and weight of the resin fuel tank can be reduced.

It is an upper perspective view of a resin fuel tank. It is a top view of a resin fuel tank. It is a bottom view of a resin fuel tank. It is a figure which shows the IV-IV sectional view of FIG. It is a figure which shows the VV line cross section of FIG. It is a figure which shows the VI-VI line cross section of FIG. It is a top view of a pyramid part. It is an upper perspective view of a pyramid part. It is a figure which shows the pyramid part which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described. The resin fuel tank 100 according to the present invention is a container for storing fuel (for example, gasoline or light oil) supplied to an internal combustion engine of a vehicle. The resin fuel tank 100 is generally provided at a position that is not visible to the passengers of the vehicle (for example, under the rear seat). Such a resin fuel tank 100 is shown in FIGS.

  FIG. 1 is an upper perspective view of the resin fuel tank 100. 2 is a top view of the resin fuel tank 100, and FIG. 3 is a bottom view of the resin fuel tank 100. As shown in FIG. 4 is shown in FIG. 4, and the VV line cross section in FIG. 2 is shown in FIG. 5. As shown in FIGS. 1 to 5, the resin fuel tank 100 has a hollow shape in which an upper flange portion 51 and a lower flange portion 52 are combined. The upper collar portion 51 is a collar member on the side shown in FIG. 2, and the lower collar portion 52 is the collar member on the side shown in FIG. In the resin fuel tank 100, the upper flange portion 51 and the lower flange portion 52 are formed in a hollow shape having a space inside with the respective hook-shaped edge portions as connection portions Z (see FIGS. 4 and 5). In addition, the resin fuel tank 100 is formed in a horizontally long rectangular shape with a corner in plan view (see FIGS. 2 and 3). Of course, it is also possible to form it in the shape of a square with a rounded corner.

  The resin fuel tank 100 including the upper collar portion 51 and the lower collar portion 52 is molded by blow molding using resin. It is preferable that the resin used for the resin fuel tank 100 has a high mechanical strength and does not react with the fuel stored in the resin fuel tank 100. Blow molding is one of thermoplastic resin molding methods, and air pressure is used in the processing.

  In blow molding, a material called a parison is melted into a pipe and extruded into divided molds. After the mold is closed, air is blown into the parison through an injection needle. The parison is inflated by air pressure, pressed against the outer mold, cooled, and solidified into a hollow shape, so that the mold can be opened and the resin fuel tank 100 can be taken out. In the resin fuel tank 100, the upper collar portion 51 and the lower collar portion 52 described above are integrally formed so as not to be separated. Therefore, the above-described connection portion Z is a name for convenience of explanation, and does not indicate a portion in which the upper collar portion 51 and the lower collar portion 52 are separately formed and connected.

  Here, let the direction along the cylindrical center part 79 of the upper collar part 51 and the lower collar part 52 be a 1st direction. The central portion 79 is a central portion having a predetermined width as shown in FIG. 1 when the upper collar portion 51 and the lower collar portion 52 are viewed as a long cylindrical shape. The direction along the central portion 79 corresponds to the direction A shown in FIG. Therefore, in the following description, the first direction will be described with reference A. Further, a second direction to be described later will be described with reference B.

  The inner surface of the cross section in the second direction B perpendicular to the first direction A at the center of the upper collar portion 51 and the lower collar portion 52 in the first direction A is connected to the connection portion Z of the upper collar portion 51 and the lower collar portion 52. The pair of first arc portions 71 extending to the center side of the upper collar portion 51 and the lower collar portion 52 and having a predetermined radius r1, and the pair of first arcs having a radius R1 larger than the predetermined radius r1. And a second arc portion 72 connected across the arc portion 71. The second direction B is a direction orthogonal to the first direction A as shown in FIG. The cross section in the second direction B is a cross section in the central portion 79 of the upper collar portion 51 and the lower collar portion 52. A cross section in the second direction B of the upper collar portion 51 and the lower collar portion 52 is shown in FIG. The cross section shown in FIG. 4 corresponds to the cross section taken along the line IV-IV in FIG.

  The inner surface of the cross section is a surface along the inner wall in the cross sectional view of the resin fuel tank 100. As shown in FIG. 4, a supply port 31, a pump attachment port 32, and a bottom portion 33 are formed in the upper collar portion 51 and the lower collar portion 52. Moreover, the cross section of the position which remove | deviated from the pump attachment port 32 along the 1st direction A from the IV-IV line in FIG. 2 becomes like the dashed-dotted line as shown in FIG. If the radius of the first arc portion 71 is r1, the radius of the second arc portion 72 is formed with a radius R1 larger than r1. Thus, the resin fuel tank 100 is formed in a hot water tampo type (rugby ball type) cross-sectional shape in a cross-sectional view as shown in FIG.

  Here, when the length along the inner surface of the first arc portion 71 is β and the length along the inner surface of the second arc portion 72 is α, the first arc portion 71 and the second arc portion 72 have α> β It is formed to become. In particular, it is preferable to form β so that it is about ½ (about half) of α. Of course, it is naturally possible to form the first arc portion 71 and the second arc portion 72 so that α <β. Further, the portion denoted by the symbol γ corresponding to the inner surface of the connecting portion Z (the portion connecting the first arc portion 71 of the upper collar portion 51 and the first arc portion 72 of the lower collar portion 52) is the first arc portion. It is preferable to form with a radius smaller than the radius r1 of 71. In addition, it is preferable that the length of the portion indicated by γ is formed such that β> γ in the relationship with β described above. In particular, it is preferable to form so that γ is about ½ (about half) of β. Of course, it is of course possible to directly connect the two first arc portions 71 having the length β without forming the portion γ.

  The inner surface of the cross section in the first direction A at the center of the upper collar part 51 and the lower collar part 52 in the second direction B is connected to the connection portion Z of the upper collar part 51 and the lower collar part 52 to connect the upper collar part 51 and A pair of third arc portions 82 extending toward the center side of the lower collar portion 52 and a connection portion 81 connected across the pair of third arc portions 82 are formed. A cross section in the first direction A is shown in FIG. The cross section shown in FIG. 5 corresponds to the cross section taken along line VV in FIG.

  As shown in FIG. 5, the inner surface of the cross section of the upper collar portion 51 and the lower collar portion 52 in the first direction A has a pair extending from the connecting portion Z of the upper collar portion 51 and the lower collar portion 52 to the center side. The third arc portion 82 is formed. The third arc portion 82 is preferably formed with the same radius r1 as the first arc portion 71. In addition, a connection portion 81 is formed between the pair of third arc portions 82. The inner surface of the cross section is a shape along the inner wall in the cross sectional view of the resin fuel tank 100 as described above. As described above, the supply port 31, the pump mounting port 32, and the bottom 33 formed in the upper collar portion 51 and the lower collar portion 52 are shown in FIG. Moreover, the cross section of the position removed from the pump attachment port 32 along the 2nd direction B from the VV line in FIG. 2 becomes like the dashed-dotted line as shown in FIG. Thus, the resin fuel tank 100 is formed in a flat and thin shape in a side view as shown in FIG.

  The resin fuel tank 100 has an inner surface with a central cross section as described above. Therefore, even when the fuel in the resin fuel tank 100 is volatilized and the pressure becomes high, the pressure can be uniformly received, so that deformation and breakage of the resin fuel tank 100 can be prevented.

  Here, as described above, it is preferable that the first arc portion 71 and the third arc portion 82 are both formed with a radius r1. If it is set as such a structure, each applicable site | part of the upper collar part 51 and the lower collar part 52 will be formed similarly to a part of spherical body surface which makes a radius r1. Thereby, even when the fuel is volatilized in the resin fuel tank 100 and the pressure is increased, the pressure is uniformly applied, so that the effect of preventing deformation and breakage can be enhanced. Thus, this resin fuel tank 100 is formed in the hot water tampo shape as a whole.

  A fuel supply port 31 stored in the resin fuel tank 100 is formed on the upper surface of the resin fuel tank 100. In the present embodiment, the supply port 31 is illustrated as being formed at a position deviated from the center of the upper collar 51, but is not limited to this position. Naturally, the supply port 31 can be formed at another position by routing an oil supply pipe (not shown) connected to an oil supply port (not shown) of the vehicle. The supply port 31 is formed with a round hole, and an oil supply pipe is connected thereto.

  An opening 32 having a recess 41 around is formed in the central portion 79 of the upper collar portion 51. The opening 32 corresponds to a pump attachment port to which a pump (not shown) for sucking out fuel stored in the resin fuel tank 100 is attached. Therefore, in the following description, the opening 32 will be described as the pump attachment port 32. By providing the depression 41 around the pump attachment port 32, the strength of the portion where the pump attachment port 32 is formed can be increased. Note that, similarly to the supply port 31 described above, the pump mounting port 32 is not limited to the illustrated position. The pump attachment port 32 is formed by a round hole.

  A bottom portion 33 having a flat surface is formed on the lower surface of the resin fuel tank 100, that is, the connecting portion 81 of the lower collar portion 52 so that the arrangement posture can be maintained when the resin fuel tank 100 is arranged in a vehicle. The It is possible to maintain the resin fuel tank 100 in an intended posture by contacting the bottom portion 33 with a flat surface of the vehicle.

  The resin fuel tank 100 is provided with a plurality of mounting portions 21. FIG. 6 is an enlarged view (sectional view) of the mounting portion 21. As shown in FIG. 6, a through hole 22 is formed in the approximate center of the attachment portion 21. The resin fuel tank 100 can be fixed by fixing the through hole 22 and a vehicle holding unit (not shown) with a bolt. In addition, when this attachment part 21 is formed, the position of the knob part 23 is a predetermined jig (not shown) so that the plate thickness in the vicinity of the attachment part 21 of the upper collar part 51 and the lower collar part 52 is not thinned. In this way, the upper hook part 51 and the lower hook part 52 are formed so that the vicinity of the attachment part 21 is not pulled outward together with the attachment part 21. Thereby, the plate | board thickness of the vicinity part of the attaching part 21 of the upper collar part 51 and the lower collar part 52 is ensured.

  At least a part of the inner and outer surfaces of the upper collar portion 51 and the lower collar portion 52 of the resin fuel tank 100 are formed by connecting a plurality of pyramidal portions 77 each having a plurality of pyramidal surfaces 78. The pyramid portion 77 corresponds to a pyramid, and the pyramid surface 78 corresponds to a surface composed of a plurality of triangles included in the pyramid. Therefore, the pyramid portion 77 is formed in a diamond shape or a pyramid shape. In the present embodiment, the pyramid portion 77 is formed so as to protrude inward with respect to the resin fuel tank 100. A top view of such a pyramid portion 77 is shown in FIG. 7, and an upper perspective view of the pyramid portion 77 is shown in FIG. Note that the pyramid portion 77 shown in FIG. 8 is exaggerated in the height direction (vertical direction) for easy understanding of the description, and is not limited to that shown in FIG.

  As shown in FIGS. 7 and 8, at least one of the plurality of pyramid surfaces 78 made of a triangle is formed of an isosceles triangle. In particular, in the present embodiment, the pyramid portion 77 is described as a quadrangular pyramid having four isosceles triangles and a pyramid surface 78. Therefore, the plurality of pyramid surfaces 78 correspond to the four pyramid surfaces 78 constituting the quadrangular pyramid. The upper collar part 51 and the lower collar part 52 are at least partially formed with the pyramid surface 78 as an inner surface and an outer surface thereof.

  One of the lines connecting each vertex 76 of the bottom surface of the pyramid portion 77 and the top 80 of the pyramid portion 77 is the first direction A along the cylindrical central portion 79 of the upper collar portion 51 and the lower collar portion 52 or It is formed along a second direction B orthogonal to the first direction A. The cylindrical central portion 79 is formed with a predetermined width along the first direction A as shown in FIG. 1 when the upper collar portion 51 and the lower collar portion 52 are cylindrical. The part corresponds.

  The bottom surface of the pyramid portion 77 corresponds to a quadrangular surface formed by connecting four vertices 76. The top 80 of the pyramidal portion 77 corresponds to the tip of a square pyramid. One line (for example, a line 77A) connecting each vertex 76 of the bottom surface of the pyramid portion 77 and the top portion 80 of the pyramid portion 77 is formed along the first direction A. Here, as described above, in the present embodiment, the pyramid portion 77 is configured to include the pyramid surface 78 including four isosceles triangles. Therefore, when the line 77A is formed along the first direction A, the line 78B is formed along the second direction B. By configuring the pyramid portion 77 in this manner, when the resin fuel tank 100 receives a load from the outside, the pyramid portion 77 absorbs the load and prevents the resin fuel tank 100 from being damaged and leaking fuel. It becomes possible.

  As shown in FIG. 1 to FIG. 3, the pyramid portion 77 is formed over substantially the entire circumference in the second direction B of the upper collar portion 51 and the lower collar portion 52, and the upper collar portion 51 and the lower collar portion 52. It is preferable to form the central portion 79 in the first direction A. In particular, the pyramid portion 77 is not formed in the pump attachment port 32, its periphery, or the bottom 33, but can be formed as necessary. The substantially entire circumference is substantially the entire circumference because the pyramid portion 77 is not formed in the connection portion Z connecting the upper collar portion 51 and the lower collar portion 52. However, it is naturally possible to form the pyramid portion 77 also in the connection portion Z between the upper collar portion 51 and the lower collar portion 52, and is within the scope of the present invention.

  As described above, at least a part of the inner surface and the outer surface of the upper collar portion 51 and the lower collar portion 52 are formed by connecting a plurality of pyramidal portions 77 each having a plurality of pyramidal surfaces 78. That is, as shown in FIGS. 4 and 5, at least a part of the inner surface and the outer surface of the upper collar part 51 and the lower collar part 52 are formed to have irregularities.

  For example, when the environmental temperature in which the resin fuel tank 100 is provided increases, the fuel evaporates in the resin fuel tank 100 and the internal pressure increases. On the other hand, when the environmental temperature becomes low, the internal pressure becomes lower than when the environmental temperature is high. As described above, the pressure in the resin fuel tank 100 also varies due to the variation in the environmental temperature.

  The pyramid portion 77 has a function of absorbing such fluctuations in internal pressure. That is, when the internal pressure of the resin fuel tank 100 is increased, the irregularities of the pyramid portion 77 are widened to increase the volume. Therefore, the internal pressure of the resin fuel tank 100 is prevented from becoming too high. On the other hand, when the internal pressure of the resin fuel tank 100 becomes low, the unevenness of the pyramid portion 77 narrows and returns to the original volume. Therefore, the internal pressure of the resin fuel tank 100 is prevented from becoming too low. As described above, the pyramid portion 77 repeats elongation and restoration as appropriate, so that the resin fuel tank 100 can be hardly cracked.

  Thus, the pyramid portion 77 also has a function of maintaining the pressure in the resin fuel tank 100 substantially constant. The pyramidal portion 77 is preferably formed on the basis of the case where the internal pressure of the resin fuel tank 100 becomes high.

[Other Embodiments]
In the said embodiment, it demonstrated that the opening part (pump attachment port 32) which has the hollow 41 in the circumference | surroundings in the center part 79 of the upper collar part 51 was formed. However, the scope of application of the present invention is not limited to this. Of course, it is also possible to form an opening (pump attachment port 32) having a recess 41 around the central portion 79 of the lower collar portion 52.

  In the above embodiment, the four pyramid surfaces 78 constituting the pyramid portion 77 are formed as isosceles triangles. In such a case, the lines 77A and 77B are formed along the first direction A and the second direction B, respectively. Explained as being. However, the scope of application of the present invention is not limited to this. One of the lines connecting each vertex 76 of the bottom surface of the pyramid portion 77 and the top 80 of the pyramid portion 77 is the first direction A along the cylindrical central portion 79 of the upper collar portion 51 and the lower collar portion 52 or Needless to say, it may be formed along the second direction B orthogonal to the first direction A. That is, it is naturally possible to form in either one of the first direction A and the second direction B. By adopting such a configuration, it is naturally possible to absorb the load from the side orthogonal to one of the lines connecting each vertex 76 and the top 80.

  In the above embodiment, the pyramid portion 77 is formed over substantially the entire circumference in the second direction B of the upper collar part 51 and the lower collar part 52, and at least in the first direction A of the upper collar part 51 and the lower collar part 52. It has been described as being formed in the central portion 79. However, the scope of application of the present invention is not limited to this. The pyramid portion 77 is formed over substantially the entire circumference of the upper collar portion 51 and the lower collar portion 52 in the first direction A, and is formed at least in the central portion 79 of the upper collar portion 51 and the lower collar portion 52 in the second direction B. Of course it is also possible to do. Even when the pyramid portion 77 is formed in this way, it is naturally possible to obtain the above-described effect.

  In the embodiment described above, the pyramid portion 77 has been described as a portion made of a quadrangular pyramid. However, the scope of application of the present invention is not limited to this. For example, it is naturally possible to form the pyramid portion 77 from a triangular pyramid. A series of such pyramid portions 77 made of triangular pyramids is shown in FIG. In such a case, it is preferable that the bottom surface formed by connecting the three vertices 76 is an equilateral triangle. It is preferable that one line 77B connecting the apex 76 and the top 80 is formed along the second direction B. It is natural that the pyramid portion 77 can suitably absorb the load received from the first direction A by forming in this way. Note that the pyramid surface 77 does not have to be all formed of an isosceles triangle, but only the hatched triangle shown in FIG. 78) need only be formed of isosceles triangles. Of course, the line 77B can be formed along the second direction B. In such a case, the pyramid portion 77 can suitably absorb the load received from the second direction B.

  In the above embodiment, it has been described that at least a part of the inner surface and the outer surface of the upper collar portion 51 and the lower collar portion 52 are formed by connecting a plurality of pyramid portions 77 each having a plurality of pyramid surfaces 78. However, the scope of application of the present invention is not limited to this. Of course, it is also possible to form a plurality of pyramidal portions 77 having a plurality of pyramidal surfaces 78 over the entire inner surface and outer surface of the upper collar portion 51 and the lower collar portion 52.

  In the above embodiment, the pyramid portion 77 has been described as being formed in a form protruding inside the resin fuel tank 100. However, the scope of application of the present invention is not limited to this. Of course, the pyramidal portion 77 may be formed so as to protrude to the outside of the resin fuel tank 100.

  INDUSTRIAL APPLICABILITY The present invention can be used for a resin fuel tank formed by blow molding and having a hollow shape in which an upper collar part and a lower collar part are combined.

51: Upper collar part 52: Lower collar part 76: Apex 77: Pyramid part 78: Pyramid surface 79: Central part 80: Top part 100: Resin fuel tank A: First direction B: Second direction

Claims (4)

In a resin fuel tank formed by blow molding and having a hollow shape in which an upper collar part and a lower collar part are combined,
A plurality of pyramid portions each having a plurality of pyramidal surfaces are connected to form at least a part of the inner surface and the outer surface of the upper collar part and the lower collar part,
At least one of the plurality of pyramidal surfaces is an isosceles triangle;
One of the lines connecting each vertex of the bottom surface of the pyramid portion and the top of the pyramid portion is in the first direction or the first direction along the cylindrical central portion of the upper collar portion and the lower collar portion. A resin fuel tank formed along a second direction orthogonal to each other.   The resin fuel tank according to claim 1, wherein the pyramid portion is a quadrangular pyramid having four isosceles triangles as a pyramid surface.   The pyramid portion is formed over substantially the entire circumference of one of the first direction and the second direction of the upper collar part and the lower collar part, and the first direction of the upper collar part and the lower collar part 3. The resin fuel tank according to claim 1, wherein the resin fuel tank is formed at least in a central portion of the other in the second direction. The inner surface of the cross section in the second direction at the center of the upper collar part and the lower collar part in the first direction along the cylindrical central part of the upper collar part and the lower collar part is the upper collar part. And a pair of first arc portions connected to the connecting portion of the lower collar and extending to the center side of the upper collar and the lower collar and having a predetermined radius, and a radius larger than the predetermined radius And a second arc portion connected across the pair of first arc portions, and
The inner surface of the cross section in the first direction at the center of the upper collar part and the lower collar part in the second direction is connected to the connection part of the upper collar part and the lower collar part, and the upper collar part and the 4. The device according to claim 1, further comprising: a pair of third arc portions extending toward a center side of the lower collar portion; and a connection portion connected across the pair of third arc portions. The resin fuel tank according to claim 1.

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