Fuel tank

Abstract

The utility model relates to a fuel tank, which can prevent a fuel cover from being blown away by gas injected from an oil supply port even if the fuel cover is detached under the condition that the internal pressure of the fuel tank rises. A fuel tank (FTK) is provided with a tank main body, a fuel tank filler (FTF), and a fuel cap (1). The fuel tank filler opening (FTF) has a pressure relief section (PR) provided on the fastening inclined surface (TIF). The pressure relief section (PR) is configured so as to form a gap between the fuel cap (1) and the fuel tank filler (FTF) by restricting the movement of the fastening protrusion of the fuel cap (1) in a state where the internal pressure of the tank body is higher than atmospheric pressure and the force in the axial direction (Da) acts on the fuel cap (1) toward the outside of the tank body.

Description

TECHNICAL FIELD

[0001] This application claims priority based on Japanese Patent Application No. 2023-217024 filed on December 22, 2023. The entire contents of the Japanese application are incorporated herein by reference.

[0002] The utility model relates to a kind of fuel tank. BACKGROUND

[0003] In the past, it is known that a fuel tank cover for closing a relatively large fuel tank used in civil engineering vehicles and the like (for example, Patent Literature 1). The existing fuel tank cover described in Patent Literature 1 has a cutout portion and a fitting portion and is detachably attached to a cylindrical cover attachment port provided on the fuel tank.

[0004] More specifically, in the above-mentioned cover attachment port, a flange portion is formed by bending the upper end portion inward. A cutout portion recessed to the radial outer side is formed at three places of the flange portion. Further, the front end portion of the flange portion is directed downward with its lower end portion as a fitting portion.

[0005] When the above-mentioned fuel tank cover is attached to the above-mentioned cover attachment port, each of the fitting projections attached to the hook pieces of the operation cover is inserted into each of the cutout portions formed in the flange portion of the cover attachment port from above, and the operation cover is covered on the cover attachment port from above. Then, the operation cover is rotated in the LOCK direction.

[0006] As a result, each of the fitting projections of the hook pieces is fitted to the fitting portion of the lower end of the flange portion from below, and the fuel tank cover is fastened to the cover attachment port. As a result, the gasket provided on the operation cover is in close contact with the upper end surface of the flange portion of the cover attachment port and is elastically deformed, thereby closing the cover attachment port.

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2006-103466

[0008] However, the above-mentioned existing fuel tank cover, if loosened for detachment in a state where the internal pressure of the fuel tank is rising, can be blown away by gas ejected from the cover attachment port of the fuel tank and lost. SUMMARY

[0009] Therefore, the utility model provides a kind of fuel tank, even in the state where the internal pressure of tank main body rises, fuel cover can be prevented by gas ejected from oil supply port and blown away when fuel cover is detached.

[0010] The utility model discloses a kind of fuel tank, with: tank main body, fuel is contained;Cylindrical fuel tank filler, set in the tank main body;And fuel cover, by making it rotate to the 1st direction around the shaft of the fuel tank filler and with the fuel tank filler fastening, to close the oil inlet of the front end of the fuel tank filler, the fuel tank filler is provided with pressure release part, the pressure release part restricts the movement of the fuel cover in the state that force is applied to the fuel cover by the internal pressure of the tank main body to the axial direction of the fuel tank filler, to form gap between the fuel cover and the fuel tank filler.

[0011] Effect of the utility model

[0012] In the fuel tank related to the above-mentioned mode, when the fuel cover is removed from the front end of the fuel tank filler provided in the tank main body, the following steps are taken. First, rotate the fuel cover to the second direction opposite to the first direction. Then, pull the fuel cover in the axial direction. In this way, the fuel cover can be removed from the front end of the fuel tank filler.

[0013] However, the fuel tank is sometimes filled with fuel by a fuel pump installed on the side surface of the tank main body or the like in a state where the oil inlet of the front end of the fuel tank filler is closed by the fuel cover. In this case, for example, the gas in the tank main body is compressed, and as a result, the internal pressure of the tank main body sometimes rises to be higher than the atmospheric pressure, thereby becoming a state where the force in the axial direction of the fuel tank filler acts on the fuel cover toward the outside of the tank main body.

[0014] In this state, for example, the operating cover of the fuel tank cover of the existing structure as in the above-mentioned patent document 1 is rotated in the loosening direction opposite to the LOCK direction, and each engagement protrusion is moved to the position of each cutout portion by sliding with respect to the engagement portion of the cover mounting portion. As a result, the engagement of each engagement protrusion in the axial direction of the cylindrical cover mounting portion with the engagement portion is released, and thereby the reaction force against the internal pressure of the fuel tank becomes not to act on each engagement protrusion of the operating cover from the engagement portion of the cover mounting portion.

[0015] As a result, the fuel tank cover of the existing structure moves in the axial direction of the cover mounting portion toward the outside of the fuel tank due to the internal pressure of the fuel tank, and each engagement protrusion passes through each cutout portion of the cover mounting portion. At this time, the fuel tank cover of the existing structure can be blown away by the gas ejected from the cover mounting portion.

[0016] In contrast, the fuel tank related to the above-mentioned mode of the utility model is provided with the pressure release portion at the fuel tank filler as described above. Therefore, if the fuel cover is rotated in the second direction opposite to the first direction in a state where the force acts on the fuel cover toward the outside of the tank main body, the movement of the fuel cover in the second direction is restricted by the pressure release portion provided at the fuel tank filler.

[0017] As described above, the pressure release portion of the fuel tank filler is configured to restrict the movement of the fuel cap to form a gap between the fuel cap and the fuel tank filler in a state where a force acts on the fuel cap toward the outside of the tank main body. Therefore, in a state where the fastening protrusion of the fuel cap is restricted from moving in the second direction and the fuel tank filler is restricted from moving in the axial direction by the pressure release portion, a gap is formed between the fuel cap and the fuel tank filler, and gas in the tank main body can be released to the atmosphere through the gap.

[0018] As a result, the internal pressure of the tank main body can be substantially reduced to the atmospheric pressure. Then, the fuel cap is further rotated in the second direction and pulled in the axial direction of the fuel tank filler. Thus, even in a state where the internal pressure of the tank main body is higher than the atmospheric pressure, the fuel cap can be prevented from being blown away, the internal pressure of the tank main body can be substantially reduced to the atmospheric pressure, and the fuel cap can be removed from the front end of the fuel tank filler.

[0019] Therefore, according to the above-described aspect of the present application, a fuel tank can be provided, in which the fuel cap can be prevented from being blown away by gas ejected from the fuel filler even in a state where the internal pressure of the tank main body is increased. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a perspective view showing a first embodiment of a fuel tank according to the present application.

[0021] Figure 2 is an enlarged perspective view showing a state of the fuel cap of the fuel tank according to the present application. Figure 1

[0022] Figure 3 is an enlarged perspective view of the fuel cap according to the present application, viewed from an oblique lower side. Figure 2

[0023] Figure 4 is a view showing a fuel tank filler of the fuel tank according to the present application, in which the fuel tank filler is cut. Figure 2

[0024] Figure 5 is a view showing a second embodiment of a fuel tank according to the present application, which corresponds to Figure 4

[0025] Figure 6 is a view showing a third embodiment of a fuel tank according to the present application, which corresponds to Figure 4

[0026] EXPLANATION OF SYMBOLS

[0027] ​​​​​1-Fuel cap, 11-Cap body, 11b-Upper wall bottom surface, 12-Retainer, 13-Fastening protrusion, AR-Rotation limiting part, C-Slit, D1-First direction, D2-Second direction, Da-Axial direction, ES-Engine start point, FO-Fuel inlet, FTF-Fuel tank filling port, FTK-Fuel tank, Ga-Gap, H-Height, MRA-Axial limiting surface, PR-Pressure relief part, PR3-Flat surface, TAF-Front end annular surface, TIF-Fastening inclined surface, TKB-Tank body. Detailed Implementation

[0028] Hereinafter, the method for implementing the utility model will be described with reference to the accompanying drawings.

[0029] [First Implementation]

[0030] Figure 1 This is a perspective view showing the first embodiment of the fuel tank FTK according to the present invention. Figure 2 It means to unload Figure 1 An enlarged 3D view of the state of the fuel cap 1 of the fuel tank FTK. Figure 3 Viewed from below at an angle Figure 2 Enlarged perspective view of fuel cap 1.

[0031] The fuel tank FTK of this embodiment is, for example, mounted in construction machinery such as hydraulic excavators, asphalt rollers, and cranes, and stores fuel such as diesel fuel supplied to the engine of the construction machinery. The fuel tank FTK includes, for example, a tank body TKB for containing fuel, a cylindrical fuel tank filling port FTF provided on the tank body TKB, and a fuel cap 1 that closes the front end of the fuel tank filling port FTF to the fuel supply port FO.

[0032] The tank body TKB is, for example, a metal container in a generally rectangular parallelepiped shape. Although not shown in the figure, the tank body TKB may be configured to have a fuel inlet on the side or bottom, and be able to be refueled via a fuel pump connected to the fuel inlet.

[0033] like Figure 2 As shown, the fuel tank filling port FTF includes, for example, a fuel inlet FO, a front annular surface TAF disposed around the fuel inlet FO, and multiple cutouts C disposed on the front annular surface TAF. Furthermore, the fuel tank filling port FTF includes, for example, an inner peripheral wall ICW, a fastening inclined surface TIF, an anti-rotation member WS, and a pressure relief part PR.

[0034] The inner peripheral wall ICW is provided, for example, so as to be vertically downward from the inner periphery of the front end annular face TAF toward the axial direction Da. The fastening inclined face TIF is provided, for example, at the lower end of the inner peripheral wall ICW so as to be inclined with respect to the front end annular face TAF in such a manner that the height H of the inner peripheral wall ICW in the axial direction Da increases more toward the front side in the fastening direction, i.e., the first direction Dl, of the fuel cap 1. In other words, the fastening inclined face TIF is provided, for example, so as to increase the distance to the front end annular face TAF more toward the first direction Dl side. Each of the fastening inclined faces TIF is provided so as to be adjacent to each of the cutouts C on the inner side of the oil supply port FO in the first direction Dl. Also, the rotation stopper WS is provided, for example, so as to be adjacent to the fastening inclined face TIF at the lower end of the end portion of the inner peripheral wall ICW in the first direction Dl.

[0035] The front end annular face TAF and the inner peripheral wall ICW are formed, for example, by bending the peripheral wall at the front end of the fuel tank filler FTF in the axial direction Da toward the radially inner side and further bending it toward the axial direction Da opposite to the front end. The front end annular face TAF is, for example, an annular flat face perpendicular to the axial direction Da and is provided at the front end of the fuel tank filler FTF so as to surround the oil supply port FO.

[0036] When the fuel cap 1 is fastened to the front end portion of the fuel tank filler FTF, the front end annular face TAF is in close contact with the gasket 15 (see Figure 3 ) of the fuel cap 1 to be described later, thereby sealing the periphery of the oil supply port FO and ensuring the airtightness of the fuel tank FTK.

[0037] The inner peripheral wall ICW is provided, for example, so as to be vertically downward from the inner periphery of the front end annular face TAF toward the inner side of the oil supply port FO in the axial direction Da and so as to surround the oil supply port FO. The inner peripheral wall ICW is the cylindrical inner wall of the fuel tank filler FTF that defines the outer periphery or the opening edge of the oil supply port FO.

[0038] The plurality of cutouts C are formed, for example, by cutting the front end annular face TAF and the inner peripheral wall ICW into a concave shape from the radially inner side toward the outer side. The plurality of cutouts C are provided, for example, at equal angular intervals in the circumferential direction of the front end annular face TAF, i.e., in the first direction Dl of the fuel cap 1. In Figure 2 In the example shown in FIG. 1, three cutouts C are provided at intervals of 120° in the circumferential direction on the front end annular face TAF of the fuel tank filler FTF. The number of cutouts C provided on the front end annular face TAF is not particularly limited.

[0039] The shape of the cutout C viewed in the axial direction Da of the fuel tank filler port FTF and the shape of the cutout C viewed in the radial direction of the fuel tank filler port FTF are, for example, substantially rectangular. That is, viewed in the axial direction Da of the fuel tank filler port FTF, the two end edges of the cutout C in the circumferential direction of the front end annular face TAF are parallel to each other and substantially parallel to the radial direction of the fuel tank filler port FTF. Also, viewed in the radial direction of the fuel tank filler port FTF, the two end edges of the cutout C in the circumferential direction of the inner peripheral wall ICW are parallel to each other and substantially parallel to the axial direction Da of the fuel tank filler port FTF.

[0040] The fastening inclined face TIF is provided at the lower end of the inner peripheral wall ICW, extends in the circumferential direction of the fuel tank filler port FTF, and is inclined at a prescribed angle with respect to the front end annular face TAF. The fastening inclined face TIF is provided between two cutouts C adjacent in the first direction Dl of the fuel cap 1, that is, in the rotation direction about the axis of the fuel tank filler port FTF. Therefore, the number of fastening inclined faces TIF is the same as the number of cutouts C. The fastening inclined face TIF is inclined at a prescribed angle with respect to the front end annular face TAF in such a manner that the height H of the inner peripheral wall ICW in the axial direction Da of the fuel tank filler port FTF increases the closer it is to the first direction Dl of the fuel cap 1.

[0041] In other words, in the axial direction Da of the fuel tank filler port FTF, the height H of the fastening inclined face TIF with respect to the front end annular face TAF is smallest at the end portion of the fastening inclined face TIF adjacent to the cutout C on the rear side in the first direction Dl of the fuel cap 1. Also, the height H of the fastening inclined face TIF is largest at the end portion of the fastening inclined face TIF adjacent to the rotation stopper WS on the front side in the first direction Dl of the fuel cap 1. In addition, as shown in Figure 2 the fastening inclined face TIF can be inclined at a prescribed angle with respect to the front end annular face TAF as a whole, or can be inclined at a prescribed angle with respect to the front end annular face TAF in part.

[0042] The rotation stopper WS is provided so as to protrude in the axial direction Da downward from the fastening inclined face TIF at the end portion of the first direction Dl of the fastening inclined face TIF. The height H of the rotation stopper WS from the front end annular face TAF is higher than the maximum height H of the fastening inclined face TIF. Viewed in the radial direction of the fuel tank filler port FTF, the rotation stopper WS has, for example, a substantially rectangular shape.

[0043] Figure 4 is a view of the fuel tank filler port FTF shown in Figure 2 cut along the center axis A on both sides of the two cutouts C and viewed in the radial direction of the fuel tank filler port FTF. As shown in Figure 2 and Figure 4As shown, the pressure release portion PR is provided to the fastening inclined surface TIF. Specifically, the pressure release portion PR is provided, for example, to the rear end portion in the first direction D1 of the fuel cap 1 on each fastening inclined surface TIF. The structure of the pressure release portion PR will be described in detail after the structure of the fuel cap 1 is described.

[0044] The fuel cap 1 is fastened to the cylindrical fuel tank filler FTF by being rotated in the first direction D1 around the axis, and closes the oil supply port FO that is opened at the front end portion in the axial direction Da of the fuel tank filler FTF. As shown in Figure 2 and Figure 3 As shown, the fuel cap 1 has a cap main body 11, a retainer 12, and a plurality of fastening protrusions 13. Also, the fuel cap 1 has, for example, a gasket 15, a disc cover 16, and a fastening member 17.

[0045] For example, as shown in Figure 2 The cap main body 11 is a bottomed cylindrical member having a short cylindrical peripheral wall 11p and an upper wall 11u provided to the upper end of the peripheral wall 11p. The upper wall 11u has, for example, a ring-shaped flat portion toward the center from the outer edge, a ring-shaped inclined portion, a ring-shaped step portion, and a cylindrical convex portion, and the central portion is higher than the lower end of the peripheral wall 11p compared to the outer edge portion.

[0046] As shown in Figure 1 In a state where the fuel cap 1 is attached to the fuel tank filler FTF, the cap main body 11 covers the front end portion of the fuel tank filler FTF. Also, in a state where the fuel cap 1 is attached to the front end portion of the fuel tank filler FTF, Figure 2 and Figure 3 The center axis a of the bottomed cylindrical cap main body 11, that is, the center axis a of the fuel cap 1, is substantially coincident with the center axis A of the fuel tank filler FTF. Also, a gap can be provided between the inner peripheral surface of the peripheral wall 11p of the cap main body 11 and the fuel tank filler FTF.

[0047] For example, as shown in Figure 3 The retainer 12 is a circular ring-shaped or circular plate-shaped member. The retainer 12 is composed of, for example, a metal plate having elasticity, and has a hardness equivalent to or higher than that of the front end ring surface TAF of the fuel tank filler FTF. For example, the retainer 12 is fixed to the upper wall bottom surface 11b of the cap main body 11 that opposes the oil supply port FO when the fuel cap 1 is attached to the fuel tank filler FTF. Also, the upper wall bottom surface 11b is the lower surface of the upper wall 11u of the cap main body 11.

[0048] A plurality of fastening protrusions 13 are provided so as to protrude from the outer periphery of the retainer 12 to the radially outer side. The plurality of fastening protrusions 13 are provided in the retainer 12 in positions, sizes, and shapes corresponding to the plurality of cutouts C formed in the front end annular face TAF of the fuel tank filler FTF, and are configured to be able to pass through the plurality of cutouts C in the axial direction Da. Details will be described later, but the plurality of fastening protrusions 13 are rotated in the first direction D1 by passing through the plurality of cutouts C in the axial direction Da, and thereby engaged with the fastening inclined face TIF on the inner side of the oil supply port FO.

[0049] Also, as shown, for example, in Figure 3 the plurality of fastening protrusions 13 have a curved shape that protrudes toward the fastening inclined face TIF when engaged therewith, and are configured to elastically deform in the axial direction Da when engaged with the fastening inclined face TIF. Also, for example, the plurality of fastening protrusions 13 are provided on the inner side of the peripheral wall 11p of the cover body 11. In other words, as shown, for example, in Figure 3 the plurality of fastening protrusions 13 are provided between the lower end of the peripheral wall 11p and the upper wall bottom face 11b of the cover body 11 in the direction of the central axis a of the fuel cap 1.

[0050] The distance d1 in the axial direction Da from the plurality of fastening protrusions 13 shown in Figure 3 to the gasket 15 disposed on the upper wall bottom face 11b of the cover body 11 is, for example, slightly less than the maximum value of the height H of the fastening inclined face TIF of the fuel tank filler FTF from the front end annular face TAF shown in Figure 2 According to this structure, if the plurality of fastening protrusions 13 are engaged with the fastening inclined face TIF and the cover body 11 is rotated in the first direction D1 until each of the fastening protrusions 13 abuts against the stopper WS, the plurality of fastening protrusions 13 elastically deform in the axial direction Da. By the elastic force of the plurality of fastening protrusions 13, the gasket 15 is compressed between the upper wall bottom face 11b of the cover body 11 and the front end annular face TAF of the fuel tank filler FTF, thereby ensuring the sealability between the upper wall bottom face 11b of the cover body 11 and the front end annular face TAF.

[0051] A disc cover 16 is mounted, for example, on the inner side of the retainer 12 to the upper wall bottom face 11b of the cover body 11. The disc cover 16 is made of, for example, a resin material such as plastic. Also, as shown, for example, in Figure 3 the disc cover 16 has a cylindrical guide portion 16g having an outer diameter corresponding to the inner diameter of the oil supply port FO and engaged with the inner side of the oil supply port FO.

[0052] The guide portion 16g is, for example, a disc-shaped portion located on the lower side of the cover 16, having a short-axis cylindrical outer peripheral surface and a flat circular bottom surface. The outer peripheral surface of the guide portion 16g may also have a tapered shape, for example, whose diameter decreases as it moves further away from the bottom surface 11b of the upper wall of the cover body 11. Therefore, when the guide portion 16g is engaged with the fuel inlet FO, the tapered outer peripheral surface guides the guide portion 16g so that its center aligns with the center of the fuel inlet FO, making it easier for the guide portion 16g to engage with the inner side of the fuel inlet FO.

[0053] The cover 16 has, for example, a circular flange at its upper end. The cover 16 is fixed to the bottom surface 11b of the upper wall of the cover body 11 by means of a retainer 12 and fastening members 17, which are three threads passing through the flange. The fastening members 17 are arranged at equal angular intervals in the circumferential direction of the retainer 12.

[0054] Gasket 15 is, for example, a ring-shaped flat rubber sheet. For example, as... Figure 3 As shown, the gasket 15 is disposed on the outermost periphery of the bottom surface 11b of the upper wall of the cover body 11. The gasket 15 is fixed to the bottom surface 11b of the upper wall of the cover body 11 by adhesive, for example, and is integrally formed with the cover body 11. Furthermore, when the bottom surface 11b of the upper wall of the cover body 11 is facing downward, the gasket 15 is disposed at a position higher than the retainer 12 and the plurality of fastening protrusions 13.

[0055] The gasket 15 functions, for example, as a seal between the cap body 11 and the fuel inlet FO of the fuel tank filler FTF. Specifically, for example, when the fastening protrusion 13 of the fuel cap 1 is engaged with the fastening inclined surface TIF of the fuel tank filler FTF and abuts against the anti-rotation member WS, the gasket 15 is compressed between the bottom surface 11b of the upper wall of the cap body 11 and the annular surface TAF of the front end of the fuel tank filler FTF. As a result, the gasket 15 is tightly sealed with the bottom surface 11b of the upper wall of the cap body 11 and the annular surface TAF, thereby sealing the space between the cap body 11 and the fuel inlet FO of the fuel tank filler FTF. Alternatively, the fuel cap 1 may not have the gasket 15. In this case, the bottom surface 11b of the upper wall of the cap body 11 can function as a seal.

[0056] The following is about Figure 2 and Figure 4 The pressure relief section PR of the inclined surface TIF for fastening, which is shown in the fuel tank filling port FTF, will be described in detail. Figure 1The fuel tank FTK shown sometimes becomes a state in which the internal pressure of the tank body TKB is higher than the atmospheric pressure, and the force in the axial direction Da acts on the fuel cap 1 toward the outside of the tank body TKB. Thus, in the state in which the internal pressure of the tank body TKB acts on the fuel cap 1, the pressure release portion PR is configured to restrict the fastening protrusion portion 13 of the fuel cap 1 from moving, thereby forming a gap Ga between the fuel cap 1 and the fuel tank filler opening FTF.

[0057] Specifically, if the fuel cap 1 is rotated in the direction opposite to the first direction D1, that is, the second direction (relaxation direction) D2, in the state in which the force in the axial direction Da acts on the fuel cap 1 as described above, each fastening protrusion portion 13 moves from each fastening inclined surface TIF toward the pressure release portion PR. The pressure release portion PR has, for example, an axial direction restriction surface MRA that engages the fastening protrusion portion 13 of the fuel cap 1 in this state to restrict movement in the axial direction Da.

[0058] In Figure 4 In the example shown, the axial direction restriction surface MRA is, for example, an inclined surface PR1 having an inclination angle with respect to the front end annular surface TAF that is larger than that of the fastening inclined surface TIF of the fuel tank filler opening FTF. In addition, the inclination angle of the inclined surface PR1 with respect to the front end annular surface TAF can be the same as that of the fastening inclined surface TIF with respect to the front end annular surface TAF. In this case, the fastening inclined surface TIF and the inclined surface PR1 are continuously provided in a straight line. The boundary between the fastening inclined surface TIF and the inclined surface PR1 is, for example, an engagement start point ES at which the fastening inclined surface TIF starts to engage with the fastening protrusion portion 13 in a state in which the internal pressure of the tank body TKB is substantially equal to the atmospheric pressure and no force in the axial direction Da other than gravity acts on the fuel cap 1.

[0059] That is, Figure 4 The upper end 13t of the fastening protrusion portion 13 of the fuel cap 1, which is indicated by a double-dot chain line, is in contact with the fastening inclined surface TIF at the engagement start point ES when the fuel cap 1 is fastened to the fuel tank filler opening FTF in a state in which the sealing portion of the fuel cap 1 is in contact with the front end annular surface TAF. Then, if the fuel cap 1 is further rotated in the first direction D1, each fastening protrusion portion 13 moves in the first direction D1 along the fastening inclined surface TIF, and is elastically deformed by being pressed in the axial direction Da toward the inside of the tank body TKB by the fastening inclined surface TIF.

[0060] Further, the pressure release portion PR has a depth d that enables the fastening protrusion portion 13 of the fuel cap 1 to move in the axial direction Da in the state in which the internal pressure of the tank body TKB is higher than the atmospheric pressure. Figure 4The gap Ga for releasing the internal pressure of the tank body TKB is formed between the gasket 15 or the upper wall bottom surface lib of the cap body 11 of the fuel cap 1 and the front end annular surface TAF of the fuel tank filler FTF. The depth d of the pressure release portion PR is the depth d in the axial direction Da from the engagement start point ES of the fastening inclined surface TIF as a reference.

[0061] Here, the depth d of the pressure release portion PR is, for example, the depth d at which the gap Ga for releasing the internal pressure of the tank body TKB can be formed in a state in which the force in the axial direction Da toward the outside of the tank body TKB is not applied to the fuel cap 1. Specifically, the axial direction restriction surface MRA is, for example, smaller in distance in the axial direction Da from the front end annular surface TAF of the fuel tank filler FTF than the engagement start point ES of the fastening inclined surface TIF at which the fastening protrusion 13 starts to be engaged in a state in which the force is not applied. More specifically, the distance (height) in the axial direction Da from the front end annular surface TAF to the axial direction restriction surface MRA is, for example, smaller than the distance (height) in the axial direction Da from the front end annular surface TAF to the engagement start point ES.

[0062] Further, the pressure release portion PR has, for example, a rotation restriction portion AR that restricts the fastening protrusion 13 from moving in a rotation direction opposite to the first direction D1, i.e., the second direction D2, in a state in which the force in the axial direction Da is applied to the fuel cap 1 as described above. The rotation restriction portion AR is disposed on the rear side of the axial direction restriction surface MRA in the first direction D1, i.e., adjacent to the axial direction restriction surface MRA in the second direction D2, and protrudes in the axial direction from the axial direction restriction surface MRA. Thus, the distance (height) in the axial direction Da from the front end annular surface TAF to the front end of the rotation restriction portion AR is, for example, greater than the distance (height) in the axial direction Da from the front end annular surface TAF to the axial direction restriction surface MRA.

[0063] Further, the distance (height) in the axial direction Da from the front end annular surface TAF to the front end of the rotation restriction portion AR is, for example, smaller than the distance (height) in the axial direction Da from the front end annular surface TAF to the engagement start point ES of the fastening inclined surface TIF. Here, as described above, the engagement start point ES is the position at which the fastening protrusion 13 starts to be engaged with the fastening inclined surface TIF in a state in which the force in the axial direction Da is not applied to the fuel cap 1. Further, in the example shown in Figs. 1 to 3, for example, the pressure release portion PR is located in the second direction D2 as viewed from the engagement start point ES of the fastening inclined surface TIF. Figure 2 and Figure 4

[0064] ​Further, the pressure release portion PR has, for example, an inclined surface PR2 adjacent to the inclined surface PR1 on the rear side in the first direction D1, that is, in the second direction D2, with respect to the axial restriction surface MRA. The inclined surface PR2 is a wall surface on the front side of the rotation restriction portion AR in the first direction D1, and functions as a rotation restriction surface MRR that restricts the rotation of the fastening protrusion 13 in the second direction D2. In Figure 4 In the example shown, the inclined angle of the inclined surface PR2 with respect to the front end annular surface TAF is substantially 90°.

[0065] Hereinafter, the effects of the fuel tank FTK of the present embodiment will be described with reference to the comparison with the conventional fuel tank cap described in the above-described Patent Document 1.

[0066] As described above, the conventional fuel tank cap described in the Patent Document 1 has a possibility of being blown away by gas such as air ejected from the cap mounting port of the fuel tank and lost if loosened for removal in a state where the internal pressure of the fuel tank is rising.

[0067] In contrast, the fuel tank FTK of the present embodiment includes a tank main body TKB that contains fuel, a cylindrical fuel tank filler port FTF provided on the tank main body TKB, and a fuel cap 1 that closes a fuel filling port FO at the front end of the fuel tank filler port FTF. The fuel cap 1 is fastened to the fuel tank filler port FTF by being rotated in a first direction that is a rotation direction about the axis of the fuel tank filler port FTF. The fuel tank filler port FTF includes a pressure release portion PR that restricts the movement of the fuel cap 1 and forms a gap Ga between the fuel cap 1 and the fuel tank filler port FTF in a state where a force in the axial direction Da of the fuel tank filler port FTF acts on the fuel cap 1 by the internal pressure of the tank main body TKB.

[0068] According to this structure, the fuel tank FTK of the present embodiment can remove the fuel cap 1 from the front end portion of the fuel tank filler port FTF by going through the following steps. First, the fuel cap 1 is rotated in a second direction D2 opposite to the first direction D1. Then, the fuel cap 1 is pulled in the axial direction Da of the fuel tank filler port FTF. Thereby, the fuel cap 1 can be removed from the front end of the fuel tank filler port FTF.

[0069] Here, the internal pressure of the fuel tank FTK sometimes rises, for example, due to the expansion of the fuel volume caused by the rise in the air temperature in the fuel tank FTK and the rise in the fuel temperature in a state where the fuel filling port FO of the fuel tank filler port FTF is closed by the fuel cap 1, or due to the decrease in the volume of the air portion in the fuel tank FTK caused by fueling of the fuel tank FTK in a state where the fuel cap is mounted. In this case, as described above, if the fuel cap 1 is rotated in the second direction D2, the fuel cap 1 is restricted from moving in the second direction D2 by the pressure release portion PR provided to the fuel tank filler port FTF.

[0070] As described above, the pressure release portion PR of the fuel tank filler FTF is configured to restrict the movement of the fuel cap 1 to form the gap Ga between the fuel cap 1 and the fuel tank filler FTF in a state where the force acts on the fuel cap 1 toward the outside of the tank main body TKB. Therefore, in a state where the movement of the fuel cap 1 in the second direction D2 and the movement of the fuel tank filler FTF in the axial direction Da are restricted by the pressure release portion PR, the gap Ga is formed between the fuel cap 1 and the fuel tank filler FTF, and the gas in the tank main body TKB can be released to the atmosphere via the gap Ga.

[0071] As a result, the internal pressure of the tank main body TKB can be substantially reduced to the atmospheric pressure. Then, the fuel cap 1 is further rotated in the second direction D2 and is pulled in the axial direction Da of the fuel tank filler FTF. Thus, even in a state where the internal pressure of the tank main body TKB is more increased than the atmospheric pressure, the fuel cap 1 can be prevented from being blown away, and the internal pressure of the tank main body TKB can be substantially reduced to the atmospheric pressure, and the fuel cap 1 can be removed from the front end of the fuel tank filler FTF.

[0072] More specifically, in the fuel tank FTK of the present embodiment, the fuel tank filler FTF has the cutout C, the fastening inclined surface TIF, and the pressure release portion PR. The cutout C is formed in the front end annular surface TAF around the fuel filler neck FO. The fastening inclined surface TIF is provided on the inner side of the fuel filler neck FO in the first direction D1 adjacent to the cutout C. Also, the fuel cap 1 has the cap main body 11, the retainer 12, and the fastening protrusion 13. The cap main body 11 covers the front end portion of the fuel tank filler FTF. The retainer 12 is a circular ring-shaped or circular plate-shaped member fixed to the upper wall bottom surface lib of the cap main body 11 opposite to the fuel filler neck FO. The fastening protrusion 13 is provided to protrude from the outer periphery of the retainer 12 to the radially outer side and to pass through the cutout C of the fuel tank filler FTF in the axial direction Da and to rotate in the first direction D1, thereby engaging with the fastening inclined surface TIF of the fuel tank filler FTF. Also, the pressure release portion PR of the fuel tank filler FTF is provided to the fastening inclined surface TIF. The pressure release portion PR is configured to restrict the movement of the fastening protrusion 13 to form the gap Ga between the fuel cap 1 and the fuel tank filler FTF in a state where the force acts.

[0073] According to this structure, the fuel tank FTK of the present embodiment can remove the fuel cap 1 from the front end portion of the fuel tank filler port FTF by going through the following steps. First, the cap main body 11 of the fuel cap 1 is rotated in the second direction D2 opposite to the first direction Dl, and the plurality of fastening protrusions 13 of the fuel cap 1 are caused to slide along the fastening inclined surface TIF of the fuel tank filler port FTF, thereby passing through the pressure release portion PR. Then, the plurality of fastening protrusions 13 of the fuel cap 1 are caused to pass through the plurality of cutouts C provided to the front end annular surface TAF of the fuel tank filler port FTF. Thereby, the fuel cap 1 can be removed from the front end portion of the fuel tank filler port FTF.

[0074] Here, as described above, the internal pressure of the fuel tank FTK sometimes rises. In this case, as described above, if the cap main body 11 of the fuel cap 1 is rotated in the second direction D2, the plurality of fastening protrusions 13 of the fuel cap 1, which are acted on by the force in the axial direction Da due to the internal pressure of the tank main body TKB, slide along the fastening inclined surface TIF of the fuel tank filler port FTF.

[0075] In this case, in the fuel tank described in the above-described existing patent document 1, the operation cap of the fuel tank cap is acted on by the internal pressure, and each of the engagement protrusions of the hook piece installed to the operation cap can pass through each of the cutout portions formed in the cap mounting port of the fuel tank. As a result, the fuel tank cap can fall off from the cap mounting port, and thus the fuel tank cap can be blown away by the gas ejected from the cap mounting port.

[0076] In contrast to this, in the fuel tank FTK of the present embodiment, if the cap main body 11 is rotated in the second direction D2 opposite to the first direction Dl in a state where the force in the axial direction Da acts on the fuel cap 1, the fastening protrusions 13 move from the fastening inclined surface TIF to the pressure release portion PR. As described above, this pressure release portion PR is configured to restrict the movement of the fastening protrusions 13 in a state where the force in the axial direction Da acts, and to form a gap Ga between the fuel cap 1 and the fuel tank filler port FTF.

[0077] Thereby, if the fastening protrusions 13 of the fuel cap 1 reach the pressure release portion PR of the fuel tank filler port FTF, a gap Ga is formed between the fuel cap 1 and the fuel tank filler port FTF in a state where the movement of the fuel cap 1 in the second direction D2 and the axial direction Da is restricted. As a result, it is possible to release the gas in the tank main body TKB to the atmosphere via this gap Ga, and thus it is possible to prevent the fuel cap 1 from falling off from the fuel tank filler port FTF, and to reduce the internal pressure of the tank main body TKB.

[0078] Therefore, according to the present embodiment, it is possible to provide a fuel tank FTK that can prevent the fuel cap 1 from being blown away by the air or the like ejected from the fuel filler port FO even in a state where the internal pressure of the tank main body TKB rises.

[0079] Also, in the fuel tank FTK of the present embodiment, the pressure release portion PR of the fuel tank filler FTF has an axial direction restriction surface MRA that restricts movement of the fastening protrusion 13 in the axial direction Da by engaging the fastening protrusion 13 in a state where the force in the axial direction Da acts on the fuel cap 1.

[0080] According to this structure, if the fuel cap 1 fastened to the fuel tank filler FTF is rotated in the second direction D2 to move the fastening protrusion 13 toward the pressure release portion PR in a state where the internal pressure of the tank body TKB is rising, movement in the axial direction Da is restricted by the axial direction restriction surface MRA. More specifically, in a state where a gap Ga is formed between the fuel cap 1 and the fuel tank filler FTF, a force in a direction opposite to the force in the axial direction Da can act on the fastening protrusion 13 from the inclined surface PR1, i.e., the axial direction restriction surface MRA, which intersects the axial direction Da. Thus, it is possible to prevent the fuel cap 1 from falling off the fuel tank filler FTF when the internal pressure of the tank body TKB is released.

[0081] Also, in the fuel tank FTK of the present embodiment, the axial direction restriction surface MRA is closer to the axial direction Da from the start engagement point ES of the fastening inclined surface TIF, at which the fastening protrusion 13 starts to engage in a state where the force in the axial direction Da does not act on the fuel cap 1, than from the front end annular surface TAF.

[0082] According to this structure, if the fuel cap 1 is rotated in the second direction D2 to move the fastening protrusion 13 toward the axial direction restriction surface MRA in a state where the force in the axial direction Da acts, a gap Ga is formed between the front end annular surface TAF and the upper wall bottom surface lib of the gasket 15 or the cap body 11. At this time, it is possible to form the gap Ga without elastically deforming the fastening protrusion 13 in the axial direction Da, and it is possible to reduce the internal pressure of the tank body TKB to substantially atmospheric pressure.

[0083] Also, in the fuel tank FTK of the present embodiment, the pressure release portion PR has a rotation restriction portion AR that restricts movement of the fastening protrusion 13 in a rotation direction opposite to the first direction D1, i.e., the second direction D2, in a state where the force in the axial direction Da acts. The rotation restriction portion AR is disposed adjacent to the axial direction restriction surface MRA in the second direction D2 and protrudes toward the axial direction Da from the axial direction restriction surface MRA.

[0084] According to this structure, if the fuel cap 1 is rotated in the second direction D2 to move the fastening protrusions 13 in the axial direction against the axial direction restriction surface MRA in a state in which the force in the above-mentioned axial direction Da acts on the fuel cap 1, the fastening protrusions 13 are restricted from moving in the second direction D2 by the rotation restriction portion AR. Thus, the fastening protrusions 13 are prevented from moving from the pressure release portion PR to the cutout C at the time of release of the internal pressure of the tank body TKB, and the fuel cap 1 can be prevented from falling off from the fuel tank filler port FTF.

[0085] Also, in the fuel tank FTK of the present embodiment, the fastening inclined surface TIF has an engagement start point ES at which the fastening protrusions 13 start to engage in a state in which the force in the above-mentioned axial direction Da does not act on the fuel cap 1. Also, the distance in the axial direction Da from the front end annular surface TAF to the front end of the rotation restriction portion AR is smaller than the distance in the axial direction Da from the front end annular surface TAF to the engagement start point ES.

[0086] According to this structure, if the fuel cap 1 is lowered in the axial direction Da of the fuel tank filler port FTF after the internal pressure of the tank body TKB is released and the internal pressure release gap Ga disappears, a gap in the axial direction Da is formed between the upper end 13t of the fastening protrusions 13 and the front end of the rotation restriction portion AR. In this state, by rotating the fuel cap 1 in the second direction D2, the fastening protrusions 13 can be moved in the second direction D2 to pass below the rotation restriction portion AR and reach the cutout C of the fuel tank filler port FTF. Also, by pulling the fuel cap 1 in the axial direction Da, each of the fastening protrusions 13 can be made to pass through each of the cutouts C of the fuel tank filler port FTF, and the fuel cap 1 can be removed from the fuel tank filler port FTF.

[0087] Also, in the fuel tank FTK of the present embodiment, if the rotation direction opposite the first direction Dl is set as the second direction D2, the pressure release portion PR is located in the second direction D2 as viewed from the engagement start point ES of the fastening inclined surface TIF at which the fastening protrusions 13 start to engage in a state in which the force in the above-mentioned axial direction Da does not act on the fuel cap 1.

[0088] According to this structure, if the fuel cap 1 fastened to the fuel tank filler port FTF is rotated in the second direction D2 in a state in which the force in the above-mentioned axial direction Da does not act, the engagement of the fastening protrusions 13 with the fastening inclined surface TIF is released at the engagement start point ES. Then, if the fuel cap 1 is further rotated in the second direction D2, the fastening protrusions 13 pass below the pressure release portion PR to reach the cutout C, and the fuel cap 1 can be removed from the fuel tank filler port FTF.

[0089] Further, when the fuel cap 1 is fastened to the fuel tank filler FTF, each fastening protrusion 13 of the fuel cap 1 is aligned with each cutout C of the front end annular face TAF of the fuel tank filler FTF and passes through in the axial direction Da. Then, if the fuel cap 1 is rotated in the first direction Dl, the fastening protrusion 13 passes below the pressure release portion PR and engages with the fastening inclined face TIF at the engagement start point ES.

[0090] Then, if the fuel cap 1 is further rotated in the first direction Dl, each fastening protrusion 13 moves along each fastening inclined face TIF in the first direction Dl, whereby each fastening protrusion 13 is elastically deformed in the axial direction Da toward the inside of the tank main body TKB. Thus, the fuel cap 1 is fastened to the fuel tank filler FTF. Therefore, according to the above-described structure, the installation and removal of the fuel cap 1 with respect to the fuel tank filler FTF can be performed without being affected by the pressure release portion PR.

[0091] Further, the fuel cap 1 of the present embodiment further includes a disc cover 16 that is installed to the upper wall bottom surface lib of the cap main body 11 on the inside of the retainer 12. The disc cover 16 has a cylindrical guide portion 16g that has an outer diameter corresponding to the inner diameter of the oil supply port FO and engages with the inside of the oil supply port FO.

[0092] According to this structure, when the plurality of fastening protrusions 13 are aligned with respect to the plurality of cutouts C of the front end annular face TAF provided to the fuel tank filler FTF, the guide portion 16g of the disc cover 16 can be engaged with the oil supply port FO. Thus, tilting of the central axis a of the fuel cap 1 with respect to the central axis A of the fuel tank filler FTF and loosening of the cap main body 11 in the radial direction are prevented, so that alignment can be easily performed. Therefore, the installation and removal of the fuel cap 1 with respect to the fuel tank filler FTF can be easily performed.

[0093] As described above, according to the present embodiment, a fuel tank FTK can be provided in which, even if the fuel cap 1 is removed in a state in which the internal pressure of the tank main body TKB is rising, the fuel cap 1 can be prevented from being blown away by gas ejected from the oil supply port FO.

[0094] [2nd Embodiment]

[0095] Hereinafter, the above-described 1st embodiment will be Figures 1 to 3 and reference will be made to Figure 5 A 2nd embodiment of the fuel tank according to the present invention will be described. With regard to the fuel tank FTK of the present embodiment, the structure of the pressure release portion PR is different from that of the fuel tank FTK of the above-described 1st embodiment. The other structures of the fuel tank FTK of the present embodiment are the same as those of the fuel tank FTK of the above-described 1st embodiment, and therefore the same parts will be denoted by the same symbols and the description thereof will be omitted.

[0096] Figure 5 is a view showing the second embodiment of the fuel tank according to the present application. The fuel tank FTK of the present embodiment has a pressure release portion PR provided to the fastening inclined surface TIF of the fuel tank filler FTF, like the fuel tank FTK of the first embodiment described above. Figure 4

[0097] In the fuel tank FTK of the present embodiment, the pressure release portion PR is located in the first direction Dl, for example, as viewed from the engagement start point ES of the fastening inclined surface TIF. Here, like the fuel tank FTK of the first embodiment described above, the engagement start point ES of the fastening inclined surface TIF is a point at which the fastening protrusion 13 of the fuel cap 1 starts to engage with the fastening inclined surface TIF in a state where the force in the axial direction Da is not acting on the fuel cap 1.

[0098] Also, in the fuel tank FTK of the present embodiment, the depth d of the pressure release portion PR can be a depth d that enables the formation of the internal pressure release gap Ga of the tank body TKB in a state where the force in the axial direction Da toward the outside of the tank body TKB is acting on the fuel cap 1. Specifically, each of the fastening protrusions 13 of the fuel cap 1 can be configured to elastically deform in the axial direction Da in the pressure release portion PR to form the internal pressure release gap Ga in a state where the force in the axial direction Da is acting.

[0099] In other words, the depth d of the pressure release portion PR can also be a depth d that does not form the internal pressure release gap Ga of the tank body TKB in a state where the force in the axial direction Da toward the outside of the tank body TKB is not acting on the fuel cap 1, for example. Also, the amount of elastic deformation of the fastening protrusion 13 at the time of internal pressure release or the size of the internal pressure release gap Ga can be appropriately set in accordance with the internal pressure of the tank body TKB that is envisaged.

[0100] Also, in the fuel tank FTK of the present embodiment, like the fuel tank FTK of the first embodiment described above, the pressure release portion PR includes the axial direction restriction surface MRA and the rotation direction restriction surface MRR. Also, in the fuel tank FTK of the present embodiment, the axial direction restriction surface MRA is a flat surface PR3 that is substantially parallel to the front end annular surface TAF of the fuel tank filler FTF. In other words, the axial direction restriction surface MRA of the pressure release portion PR is a flat surface that is perpendicular to the axial direction Da of the fuel tank filler FTF, for example.

[0101] ​Also, in the fuel tank FTK of the present embodiment, the rotation restriction surface MRR is an inclined surface PR2 inclined in a manner that the distance (height H) from the axial direction Da of the front end annular surface TAF increases in a second direction D2 opposite to the first direction Dl of the fuel cap 1. The inclination angle of the inclined surface PR2 with respect to the front end annular surface TAF is, for example, an acute angle smaller than 90°. Also, the pressure release portion PR includes, for example, an inclined surface PRl inclined in a manner that the distance (height H) from the axial direction Da of the front end annular surface TAF increases in the first direction Dl of the fuel cap 1. The inclination angle of the inclined surface PRl with respect to the front end annular surface TAF is, for example, an acute angle smaller than 90°.

[0102] In the fuel tank FTK of the present embodiment, if the cap main body 11 is rotated in the second direction D2 opposite to the first direction Dl in the state where the force in the above-described axial direction Da acts on the fuel cap 1, the fastening protrusion 13 also moves from the fastening inclined surface TIF to the pressure release portion PR. As with the pressure release portion PR of the above-described first embodiment, this pressure release portion PR is configured to restrict the movement of the fastening protrusion 13 in the state where the force in the above-described axial direction Da acts and to form the gap Ga between the fuel cap 1 and the fuel tank filler opening FTF.

[0103] Therefore, in the present embodiment as well as in the above-described first embodiment, it is possible to provide a fuel tank FTK that can prevent the fuel cap 1 from being blown away by gas ejected from the fuel filler opening FO even when the fuel cap 1 is removed in a state where the internal pressure of the tank main body TKB is rising.

[0104] Also, in the fuel tank FTK of the present embodiment, it is possible to be configured such that, in the state where the force in the above-described axial direction Da acts on the fuel cap 1, the fastening protrusion 13 of the fuel cap 1 is elastically deformed in the axial direction Da in the pressure release portion PR of the fuel tank filler opening FTF to form the gap Ga.

[0105] According to this structure, if the gas inside the tank main body TKB is released from the gap Ga and the internal pressure of the tank main body TKB is reduced, the force in the above-described axial direction Da acting on the fuel cap 1 decreases, and thus the amount of elastic deformation of the fastening protrusion 13 decreases. As a result, before the internal pressure of the tank main body TKB is reduced to the atmospheric pressure, the gap Ga between the fuel cap 1 and the front end annular surface TAF of the fuel tank filler opening FTF disappears, and the gasket 15 or the upper wall bottom surface lib of the cap main body 11 is pressed against the front end annular surface TAF. Therefore, when the fuel cap 1 is relaxed and the fastening protrusion 13 is moved to the pressure release portion PR, it is possible to reduce the volume of gas released from the fuel tank filler opening FTF.

[0106] Further, in the fuel tank FTK of the present embodiment, the axial direction restricting surface MRA of the pressure release portion PR is a flat surface PR3 that is perpendicular to the axial direction Da of the fuel tank filler port FTF.

[0107] According to this structure, when the cap main body 11 is rotated in the second direction D2 to move the fastening protrusions 13 to the flat surfaces PR3 of the pressure release portions PR in a state where the force in the above-mentioned axial direction Da acts on the fuel cap 1, the component of the second direction D2 can be prevented from acting on the fastening protrusions 13. Thus, the fastening protrusions 13 are prevented from reaching the notches C of the fuel tank filler port FTF in a state where the force in the above-mentioned axial direction Da acts on the fuel cap 1, and the fuel cap 1 can be more reliably prevented from falling off the fuel tank filler port FTF.

[0108] Further, in the fuel tank FTK of the present embodiment, the pressure release portion PR is located in the first direction Di as viewed from the engagement start point ES of the fastening inclined surface TIF. Here, as described above, the engagement start point ES is a point at which the fastening protrusion 13 starts to engage with the fastening inclined surface TIF in a state where the force in the above-mentioned axial direction Da does not act on the fuel cap 1.

[0109] According to this structure, as described above, the fuel tank FTK of the present embodiment can rotate the fuel cap 1 in the second direction D2 to move the fastening protrusions 13 to the pressure release portions PR of the fastening inclined surfaces TIF provided to the fuel tank filler port FTF. Further, if the fuel cap 1 is further rotated in the second direction D2 after the gap Ga is formed between the fuel cap 1 and the fuel tank filler port FTF to reduce the internal pressure of the tank main body TKB, the fastening protrusions 13 are moved in the second direction D2 to engage with the fastening inclined surfaces TIF again. Then, if the fuel cap 1 is further rotated in the second direction D2, the fastening protrusions 13 are moved in the second direction D2 to reach the notches C via the engagement start points ES, and thus the fuel cap 1 can be detached from the fuel tank filler port FTF.

[0110] Here, as described above, the pressure release portion PR of the present embodiment has the inclined surface PR2 that is inclined at an angle smaller than 90° with respect to the front end annular surface TAF in a manner that the distance from the axial direction Da of the front end annular surface TAF increases toward the second direction D2. According to this structure, the fuel cap 1 can be rotated in the second direction D2 to move the fastening protrusions 13 along the inclined surfaces PR2 after the internal pressure of the tank main body TKB is released. As a result, the fastening protrusions 13 of the fuel cap 1 can be engaged with the fastening inclined surfaces TIF that are adjacent to the pressure release portions PR provided to the fuel tank filler port FTF in the second direction D2.

[0111] Further, the inclined surface PR2 of the pressure release portion PR also functions as a rotation restriction surface MRR that restricts the rotation of each fastening protrusion 13 in the second direction D2 in a state where a force in the above-mentioned axial direction Da acts on the fuel cap 1. According to this structure, it is possible to more reliably prevent the fuel cap 1 from falling off the fuel tank filler port FTF by preventing each fastening protrusion 13 from reaching each cutout C of the fuel tank filler port FTF in a state where a force in the above-mentioned axial direction Da acts on the fuel cap 1.

[0112] [3rd Embodiment]

[0113] Hereinafter, the above-mentioned 1st Embodiment of the fuel tank according to the present application will be described with reference to the above-mentioned Figures 1 to 3 , and reference will be made to Figure 6 A 3rd Embodiment of the fuel tank according to the present application will be described. In the fuel tank FTK of this Embodiment, the structure of the pressure release portion PR is different from that of the fuel tank FTK of the above-mentioned 2nd Embodiment. The other structure of the fuel tank FTK of this Embodiment is the same as that of the fuel tank FTK of the above-mentioned 2nd Embodiment, and therefore the same parts will be designated by the same symbols and the description thereof will be omitted.

[0114] Figure 6 is a view that shows a 3rd Embodiment of the fuel tank according to the present application, which corresponds to Figure 4 of the above-mentioned 2nd Embodiment. Like the fuel tank FTK of the above-mentioned 2nd Embodiment, the fuel tank FTK of this Embodiment has a pressure release portion PR provided to the fastening inclined surface TIF of the fuel tank filler port FTF. Further, like the pressure release portion PR of the above-mentioned 2nd Embodiment, the pressure release portion PR of this Embodiment has an inclined surface PR1 and an axial direction restriction surface MRA that is a flat surface PR3.

[0115] On the other hand, unlike the pressure release portion PR of the above-mentioned 2nd Embodiment, the pressure release portion PR of this Embodiment does not have a rotation restriction surface MRR that is an inclined surface PR2. Further, in the fuel tank FTK of this Embodiment, for example, each fastening protrusion 13 of the fuel cap 1 starts engagement with the inclined surface PR1 at an engagement start point ES on the inclined surface PR1 when the fuel cap 1 is fastened to the fuel tank filler port FTF.

[0116] In addition, for example, as shown by a broken line in Figure 6 , the pressure release portion PR of this Embodiment can be provided in the second direction D2 as viewed from the engagement start point ES on the fastening inclined surface TIF. At this time, the pressure release portion PR can include, for example, the axial direction restriction surface MRA that is a flat surface PR3 and an inclined surface PR4. The inclined surface PR4 is provided, for example, to an end portion of the flat surface PR3 on the front side of the first direction D1, and is formed in a step shape having an inclined angle of substantially 90° with respect to the front end annular surface TAF.

[0117] In the fuel tank FTK of the present embodiment, if the lid main body 11 is rotated in the second direction D2 opposite to the first direction D1 in the state where the force in the axial direction Da acts on the fuel cap 1, the fastening protrusions 13 also move from the fastening inclined surface TIF to the pressure release portion PR. As with the pressure release portion PR of the above-described second embodiment, this pressure release portion PR is configured to restrict the movement of the fastening protrusions 13 in the state where the force in the axial direction Da acts and to form the gap Ga between the fuel cap 1 and the fuel tank filler opening FTF.

[0118] More specifically, the fastening protrusions 13 that have moved from the fastening inclined surface TIF to the pressure release portion PR are restricted from moving in the axial direction Da by the axial direction restriction surfaces MRA that are flat surfaces PR3 perpendicular to the axial direction Da of the fuel tank filler opening FTF. Also, by the force in the axial direction Da acting on the fuel cap 1, a perpendicular resistance acts between each axial direction restriction surface MRA and each fastening protrusion 13, thereby generating a frictional force that hinders each fastening protrusion 13 from moving in the second direction D2.

[0119] Thus, each fastening protrusion 13 of the fuel cap 1 is prevented from reaching each notch C of the fuel tank filler opening FTF, and thus the fuel cap 1 can be prevented from falling off the fuel tank filler opening FTF. Therefore, in the present embodiment as well, as with the above-described second embodiment, a fuel tank FTK can be provided that can prevent the fuel cap 1 from being blown away by air or the like ejected from the oil supply port FO even if the fuel cap 1 is removed in a state where the internal pressure of the tank main body TKB is rising.

[0120] As described above, in the present embodiment, a fuel tank FTK can be provided that can prevent the fuel cap 1 from being blown away by air or the like ejected from the oil supply port FO even if the fuel cap 1 is removed in a state where the internal pressure of the tank main body TKB is rising.

[0121] The preferred embodiments of the present application have been described in detail above. However, the present application is not limited to the above-described embodiments. The above-described embodiments can be applied to various modifications or substitutions and the like without departing from the scope of the present application. Also, the features described separately can be combined as long as no technical contradictions arise.

Claims

1. A fuel tank comprising: a tank main body that contains fuel; a cylindrical fuel tank filler provided to the tank main body; and a fuel cap that is fastened to the fuel tank filler by being rotated in a first direction around an axis of the fuel tank filler to thereby close a fuel supply port of a front end of the fuel tank filler, wherein the fuel tank filler includes a pressure release portion that restricts movement of the fuel cap in a state where a force in the axial direction of the fuel tank filler is applied to the fuel cap by an internal pressure of the tank main body to thereby form a gap between the fuel cap and the fuel tank filler.

2. The fuel tank according to claim 1, wherein the fuel tank filler has a cutout formed in a front end annular surface around the fuel supply port and a fastening inclined surface provided to an inner side of the fuel supply port adjacent to the cutout in the first direction, the fuel cap has a cap main body that covers a front end portion of the fuel tank filler, a circular ring-shaped retainer fixed to an upper wall bottom surface of the cap main body opposite the fuel supply port, and a fastening protrusion portion that protrudes from an outer peripheral edge of the retainer to a radially outer side and is provided so as to be engaged with the fastening inclined surface by being rotated in the first direction with the cutout in the axial direction of the fuel tank filler, and the pressure release portion is provided to the fastening inclined surface and configured to restrict movement of the fastening protrusion portion in the state where the force is applied to thereby form the gap between the fuel cap and the fuel tank filler.

3. The fuel tank according to claim 2, wherein the fastening protrusion portion is configured to be elastically deformed in the axial direction in the pressure release portion in the state where the force is applied to thereby form the gap.

4. The fuel tank according to claim 2, wherein the pressure release portion has an axial direction restriction surface that engages the fastening protrusion portion in the state where the force is applied to thereby restrict movement in the axial direction.

5. The fuel tank according to claim 4, wherein the axial direction restriction surface is located closer to the front end annular surface than a start point of engagement of the fastening inclined surface at which the fastening protrusion portion starts to be engaged in a state where the force is not applied.

6. The fuel tank according to claim 4 or 5, wherein the axial direction restriction surface is a flat surface perpendicular to the axial direction.

7. The fuel tank according to claim 4 or 5, wherein the pressure release portion has a rotation restriction portion that restricts movement of the fastening protrusion portion in a second direction opposite the first direction in the state where the force is applied, the rotation restriction portion is provided adjacent to the axial direction restriction surface in the second direction and protrudes from the axial direction restriction surface toward the axial direction.

8. The fuel tank according to claim 7, wherein the fastening inclined surface has a start point of engagement at which the fastening protrusion portion starts to be engaged in a state where the force is not applied, and a distance in the axial direction from the front end annular surface to a front end of the rotation restriction portion is shorter than a distance in the axial direction from the front end annular surface to the start point of engagement. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 9. The fuel tank according to claim 2, wherein The pressure release portion is located in the first direction, viewed from a start point of engagement of the fastening inclined surface with which the fastening protrusion starts to engage in a state in which the force is not applied.

10. The fuel tank according to claim 2, wherein The pressure release portion is located in the second direction, viewed from a start point of engagement of the fastening inclined surface with which the fastening protrusion starts to engage in a state in which the force is not applied, if a direction of rotation opposite to the first direction is defined as the second direction.

Images