Fuel tank

Abstract

To provide a fuel tank that is able to prevent a fuel cap from being blown off by gas jetted from an oil filler port even if the fuel cap is removed in a state that the internal pressure of the fuel tank is high.SOLUTION: A fuel tank FTK includes a tank main body, a fuel tank filler FTF, and a fuel cap 1. The fuel tank filler FTF has a pressure release portion PR provided on a fastening inclined surface TIF. The pressure release portion PR is configured to define a gap between the fuel cap 1 and the fuel tank filler FTF, by restricting movement of a fastening protrusion of the fuel cap 1 while internal pressure of the tank main body is higher than atmospheric pressure and a force in an axial direction Da is applied to the fuel cap 1 toward an outer side of the tank main body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a fuel tank.

Background Art

[0002] Conventionally, a fuel tank cap for sealing a relatively large fuel tank used in construction vehicles and the like is known (for example, Patent Document 1). The conventional fuel tank cap described in Patent Document 1 has a notch portion and an engaging portion and is detachably attached to a cylindrical cap mounting port provided in the fuel tank.

[0003] More specifically, the cap mounting port has a flange portion bent inward at the upper end portion. Notch portions that are recessed radially outward are formed at three locations on this flange portion. Further, the tip end portion of the flange portion is directed downward, and its lower end portion serves as an engaging portion.

[0004] When mounting the fuel tank cap to the cap mounting port, each engaging convex portion of the latch piece attached to the operation cap is inserted into each notch portion formed in the flange portion of the cap mounting port from above, and the operation cap is placed over the cap mounting port from above. Then, the operation cap is rotated in the LOCK direction.

[0005] As a result, each engaging convex portion of the latch piece engages with the engaging portion at the lower end of the flange portion from below, and the fuel tank cap is fastened to the cap mounting port. As a result, the packing provided on the operation cap closely adheres to the upper end surface of the flange portion of the cap mounting port and elastically deforms, thereby sealing the cap mounting port.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, when the conventional fuel tank cap is loosened for removal while the internal pressure of the fuel tank is increased, there is a risk that it may be blown away and lost by the gas ejected from the cap mounting opening of the fuel tank.

[0008] Therefore, the present disclosure provides a fuel tank capable of preventing the fuel cap from being blown away by the gas ejected from the fuel filler port even when the fuel cap is removed while the internal pressure of the tank body is increased.

Means for Solving the Problems

[0009] One aspect of the present disclosure provides a fuel tank including a tank body for storing fuel, a cylindrical fuel tank filler provided on the tank body, and a fuel cap that is fastened to the fuel tank filler by rotating in a first direction around the axis of the fuel tank filler to close a fuel filler port at the tip of the fuel tank filler. The fuel tank filler includes a pressure release portion that restricts the movement of the fuel cap in a state where an axial force of the fuel tank filler acts on the fuel cap due to the internal pressure of the tank body, and forms a gap between the fuel cap and the fuel tank filler.

Advantages of the Invention

[0010] In the fuel tank according to the above aspect, to remove the fuel cap from the tip of the fuel tank filler provided on the tank body, the following procedure is taken. First, the fuel cap is rotated in a second direction opposite to the first direction. Next, the fuel cap is pulled up in the axial direction. Thereby, the fuel cap can be removed from the tip of the fuel tank filler.

[0011] By the way, the fuel tank may be refueled by a fuel pump attached to the side surface of the tank body or the like with the fuel filler opening at the tip of the fuel filler closed by a fuel cap. In such a case, for example, when the gas in the tank body is compressed, the internal pressure of the tank body rises and becomes higher than the atmospheric pressure, and an axial force of the fuel filler may act on the fuel cap toward the outside of the tank body.

[0012] In such a state, for example, the operation cap of the fuel tank cap having a conventional structure as in Patent Document 1 is rotated in a relaxation direction opposite to the LOCK direction, and each engaging convex portion is slid with respect to the engaging portion of the cap mounting port and moved to the position of each notch portion. Then, the engagement between each engaging convex portion and the engaging portion in the axial direction of the cylindrical cap mounting port is released, and a reaction force against the internal pressure of the fuel tank does not act from the engaging portion of the cap mounting port to each engaging convex portion of the operation cap.

[0013] As a result, the fuel tank cap with the conventional structure moves in the axial direction of the cap mounting port toward the outside of the fuel tank under the internal pressure of the fuel tank, and each engaging convex portion passes through each notch portion of the cap mounting port. At this time, the fuel tank cap with the conventional structure may be blown off by the gas ejected from the cap mounting port.

[0014] On the other hand, in the fuel tank according to the above aspect of the present disclosure, as described above, the pressure release portion is provided in the fuel filler. Therefore, when the fuel cap is rotated in the second direction opposite to the first direction in a state where a force acts on the fuel cap toward the outside of the tank body, the movement of the fuel cap in the second direction is restricted by the pressure release portion provided in the fuel filler.

[0015] As described above, the pressure release portion of this fuel tank filler is configured to regulate the movement of the fuel cap and form a gap between the fuel cap and the fuel tank filler when a force acts on the fuel cap toward the outside of the tank body. Therefore, a gap is formed between the fuel cap and the fuel tank filler while the movement of the fastening protrusion of the fuel cap in the second direction and the movement of the fuel tank filler in the axial direction are regulated by the pressure release portion, and the gas in the tank body can be discharged into the atmosphere through the gap.

[0016] As a result, the internal pressure of the tank body can be reduced to approximately atmospheric pressure. After that, the fuel cap is further rotated in the second direction and pulled up in the axial direction of the fuel tank filler. Thereby, even when the internal pressure of the tank body rises above atmospheric pressure, the internal pressure of the tank body can be reduced to approximately atmospheric pressure while preventing the fuel cap from being blown off, and the fuel cap can be removed from the tip of the fuel tank filler.

[0017] Therefore, according to the above aspect of the present disclosure, it is possible to provide a fuel tank that can prevent the fuel cap from being blown off by the gas ejected from the fuel filling port even when the fuel cap is removed while the internal pressure of the tank body is increased.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

[0020] [Embodiment 1] FIG. 1 is a perspective view showing Embodiment 1 of a fuel tank FTK according to the present disclosure. FIG. 2 is an enlarged perspective view showing a state where a fuel cap 1 of the fuel tank FTK in FIG. 1 is removed. FIG. 3 is an enlarged perspective view of the fuel cap 1 in FIG. 2 as viewed obliquely from below.

[0021] The fuel tank FTK of the present embodiment is mounted on a work machine such as a hydraulic excavator, an asphalt finisher, or a crane, and stores fuel such as light oil supplied to the engine of the work machine. The fuel tank FTK includes, for example, a tank body TKB that stores fuel, a cylindrical fuel tank filler FTF provided on the tank body TKB, and a fuel cap 1 that closes a fuel filling port FO at the tip of the fuel tank filler FTF.

[0022] The tank body TKB is, for example, a metal container having a substantially rectangular parallelepiped shape. Although not shown, the tank body TKB may have a fuel inlet on, for example, a side surface or a bottom surface, and may be provided so that fuel can be replenished through a fuel pump connected to the fuel inlet.

[0023] The fuel tank filler FTF includes, for example, as shown in FIG. 2, a fuel filling port FO, a tip annular surface TAF provided around the fuel filling port FO, and a plurality of notches C provided on the tip annular surface TAF. The fuel tank filler FTF also includes, for example, an inner circumferential wall ICW, a fastening inclined surface TIF, a rotation stopper WS, and a pressure release portion PR.

[0024] The inner peripheral wall ICW is provided, for example, by hanging down in the axial direction Da from the inner peripheral edge of the tip annular surface TAF. The fastening inclined surface TIF is provided, for example, at the lower end of the inner peripheral wall ICW, and is inclined with respect to the tip annular surface TAF such that the height H in the axial direction Da of the inner peripheral wall ICW increases toward the front side in the first direction D1, which is the fastening direction of the fuel cap 1. In other words, the fastening inclined surface TIF, for example, has an increasing distance from the tip annular surface TAF toward the first direction D1 side. Each fastening inclined surface TIF is provided inside the fuel filling port FO adjacent to the first direction D1 with respect to each notch C. Further, the anti-rotation WS is provided, for example, at the lower end of the end portion of the inner peripheral wall ICW in the first direction D1, adjacent to the fastening inclined surface TIF.

[0025] The tip annular surface TAF and the inner peripheral wall ICW are formed, for example, by bending the peripheral wall at the axial Da tip of a cylindrical straight pipe fuel tank filler FTF radially inward, and further bending it in the axial direction Da opposite to the tip. The tip annular surface TAF is, for example, an annular flat surface perpendicular to the axial direction Da, provided at the tip of the fuel tank filler FTF and surrounding the fuel filling port FO.

[0026] When the fuel cap 1 is fastened to the tip portion of the fuel tank filler FTF, the tip annular surface TAF adheres to the packing 15 (see FIG. 3) of the fuel cap 1 described later, thereby sealing the periphery of the fuel filling port FO and ensuring the airtightness of the fuel tank FTK.

[0027] The inner peripheral wall ICW is provided, for example, by hanging down in the axial direction Da from the inner peripheral edge of the tip annular surface TAF to the inside of the fuel filling port FO so as to surround the fuel filling port FO. The inner peripheral wall ICW is the cylindrical inner wall of the fuel tank filler FTF that defines the outer peripheral edge or the opening edge of the fuel filling port FO.

[0028] The plurality of notches C are formed, for example, by notching the tip annular surface TAF and the inner peripheral wall ICW in a concave shape from the radially inner side to the outer side. The plurality of notches C are provided at equal angular intervals, for example, in the circumferential direction of the tip annular surface TAF, that is, in the first direction D1 of the fuel cap 1. In the example shown in FIG. 2, three notches C are provided at 120° intervals in the circumferential direction on the tip annular surface TAF of the fuel tank filler FTF. Note that the number of notches C provided on the tip annular surface TAF is not particularly limited.

[0029] The shape of the notch C as viewed from the axial direction Da of the fuel tank filler FTF and the shape of the notch C as viewed from the radial direction of the fuel tank filler FTF are, for example, generally rectangular. That is, both end edges of the notch C in the circumferential direction of the tip annular surface TAF are parallel to each other as viewed from the axial direction Da of the fuel tank filler FTF and are generally parallel to the radial direction of the fuel tank filler FTF. Also, both end edges of the notch C in the circumferential direction of the inner peripheral wall ICW are parallel to each other as viewed from the radial direction of the fuel tank filler FTF and are generally parallel to the axial direction Da of the fuel tank filler FTF.

[0030] The fastening inclined surface TIF is provided at the lower end of the inner peripheral wall ICW, extends in the circumferential direction of the fuel tank filler FTF, and is inclined at a predetermined angle with respect to the tip annular surface TAF. The fastening inclined surface TIF is provided between two notches C adjacent to each other in the first direction D1 of the fuel cap 1 which is the rotational direction around the axis of the fuel tank filler FTF. Therefore, the number of fastening inclined surfaces TIF is the same as the number of notches C. The fastening inclined surface TIF is inclined at a predetermined angle with respect to the tip annular surface TAF so as to increase the height H of the inner peripheral wall ICW in the axial direction Da of the fuel tank filler FTF toward the first direction D1 side of the fuel cap 1.

[0031] In other words, in the axial direction Da of the fuel tank filler FTF, the height H of the fastening inclined surface TIF with respect to the tip annular surface TAF is minimized at the end of the fastening inclined surface TIF adjacent to the notch C on the rear side in the first direction D1 of the fuel cap 1. Further, the height H of this fastening inclined surface TIF is maximized at the end of the fastening inclined surface TIF adjacent to the anti-rotation WS on the front side in the first direction D1 of the fuel cap 1. Note that, as shown in FIG. 2, the entire fastening inclined surface TIF may be inclined at a predetermined angle with respect to the tip annular surface TAF, or a part thereof may be inclined at a predetermined angle with respect to the tip annular surface TAF.

[0032] The anti-rotation WS is provided at the end of the fastening inclined surface TIF in the first direction D1 so as to project axially in the direction Da downward from the fastening inclined surface TIF. The height H of the anti-rotation WS from the tip annular surface TAF is higher than the maximum height H of the fastening inclined surface TIF. The anti-rotation WS has, for example, a substantially rectangular shape when viewed from the radial direction of the fuel tank filler FTF.

[0033] FIG. 4 is a view of the fuel tank filler FTF shown in FIG. 2 cut along the central axis A on both sides of the two notches C and viewed from the radial direction of the fuel tank filler FTF to see the fastening inclined surface TIF. As shown in FIGS. 2 and 4, the pressure release portion PR is provided on the fastening inclined surface TIF. Specifically, the pressure release portion PR is provided, for example, at the rear end portion in the first direction D1 of the fuel cap 1 on each fastening inclined surface TIF. The configuration of the pressure release portion PR will be described in detail after the configuration of the fuel cap 1 is explained.

[0034] The fuel cap 1 is rotated and fastened in the first direction D1 around the axis with respect to the cylindrical fuel tank filler FTF, and closes the fuel filling port FO that opens at the tip portion in the axial direction Da of the fuel tank filler FTF. As shown in FIGS. 2 and 3, the fuel cap 1 includes a cap body 11, a retainer 12, and a plurality of fastening protrusions 13. Further, the fuel cap 1 includes, for example, a packing 15, a disk cap 16, and a fastening member 17.

[0035] The cap body 11 is, for example, as shown in FIG. 2, a bottomed cylindrical member having a short-axis cylindrical peripheral wall 11p and an upper wall 11u provided at the upper end of the peripheral wall 11p. The upper wall 11u has, for example, an annular flat portion, an annular inclined portion, an annular stepped portion, and a columnar convex portion from the outer edge toward the center, and the height from the lower end of the peripheral wall 11p is higher at the central portion than at the outer edge portion.

[0036] As shown in FIG. 1, in a state where the fuel cap 1 is attached to the fuel tank filler FTF, the cap body 11 covers the tip of the fuel tank filler FTF. Note that in a state where the fuel cap 1 is attached to the tip of the fuel tank filler FTF, the central axis a of the bottomed cylindrical cap body 11 shown in FIGS. 2 and 3, that is, the central axis a of the fuel cap 1 substantially coincides with the central axis A of the fuel tank filler FTF. Further, a gap may be provided between the inner peripheral surface of the peripheral wall 11p of the cap body 11 and the fuel tank filler FTF.

[0037] The retainer 12 is, for example, as shown in FIG. 3, an annular or disc-shaped member. The retainer 12 is, for example, composed of an elastic metal plate and has a hardness equal to or higher than the hardness of the tip annular surface TAF of the fuel tank filler FTF. The retainer 12 is, for example, fixed to the bottom surface 11b of the upper wall of the cap body 11 facing the fuel filling port FO when the fuel cap 1 is attached to the fuel tank filler FTF. Note that the bottom surface 11b of the upper wall is the lower surface of the upper wall 11u of the cap body 11.

[0038] The plurality of fastening protrusions 13 are provided so as to protrude radially outward from the outer peripheral edge of the retainer 12. The plurality of fastening protrusions 13 are provided at positions, sizes, and shapes corresponding to the plurality of notches C formed in the tip annular surface TAF of the fuel tank filler FTF in the retainer 12, and are configured to be able to pass through the plurality of notches C in the axial direction Da. Although details will be described later, the plurality of fastening protrusions 13 engage with the fastening inclined surface TIF inside the fuel filling port FO by passing the plurality of notches C in the axial direction Da and rotating in the first direction D1.

[0039] Further, as shown in FIG. 3 for example, the plurality of fastening protrusions 13 have a curved shape that protrudes toward the fastening inclined surface TIF when engaged with the fastening inclined surface TIF, and are configured to elastically deform in the axial direction Da when engaged with the fastening inclined surface TIF. Further, the plurality of fastening protrusions 13 are provided, for example, inside the peripheral wall 11p of the cap body 11. In other words, the plurality of fastening protrusions 13 are provided, for example, as shown in FIG. 3, between the lower end of the peripheral wall 11p of the cap body 11 and the bottom surface 11b of the upper wall in the direction along the central axis a of the fuel cap 1.

[0040] The axial distance d1 from the plurality of fastening protrusions 13 shown in FIG. 3 to the packing 15 disposed on the bottom surface 11b of the upper wall of the cap body 11 is slightly smaller than the maximum value of the height H from the tip annular surface TAF of the fastening inclined surface TIF of the fuel tank filler FTF shown in FIG. 2. With this configuration, when the plurality of fastening protrusions 13 are engaged with the fastening inclined surface TIF and the cap body 11 is rotated in the first direction D1 until each fastening protrusion 13 abuts against the anti-rotation WS, the plurality of fastening protrusions 13 elastically deform in the axial direction Da. Due to the elastic force of the plurality of fastening protrusions 13, the packing 15 is compressed between the bottom surface 11b of the upper wall of the cap body 11 and the tip annular surface TAF of the fuel tank filler FTF, and the sealing performance between the bottom surface 11b of the upper wall of the cap body 11 and the tip annular surface TAF is ensured.

[0041] The disk cap 16 is attached, for example, to the bottom surface 11b of the upper wall of the cap body 11 inside the retainer 12. The disk cap 16 is made of a resin material such as plastic, for example. Further, as shown in FIG. 3 for example, the disk cap 16 has a cylindrical guide portion 16g having an outer diameter corresponding to the inner diameter of the fuel filling port FO and engaging inside the fuel filling port FO.

[0042] The guide portion 16g is, for example, a disk-shaped portion provided on the lower side of the disk cap 16, and has a short-axis cylindrical outer peripheral surface and a flat circular bottom surface. The outer peripheral surface of the guide portion 16g may have, for example, a tapered shape in which the diameter becomes smaller as it moves away from the bottom surface 11b of the upper wall of the cap body 11. Thereby, when engaging the guide portion 16g with the fuel filler port FO, the guide portion 16g can be guided by the tapered outer peripheral surface so that the center of the guide portion 16g coincides with the center of the fuel filler port FO, and it is possible to easily engage the guide portion 16g inside the fuel filler port FO.

[0043] The disk cap 16 has, for example, a disk-shaped flange portion at its upper end. The disk cap 16 is fixed to the bottom surface 11b of the upper wall of the cap body 11 by, for example, three fastening members 17 as screws that pass through the retainer 12 and the flange portion. The fastening members 17 are arranged, for example, at equal angular intervals in the circumferential direction of the retainer 12.

[0044] The packing 15 is, for example, an annular flat rubber. The packing 15 is arranged, for example, at the outermost peripheral portion of the bottom surface 11b of the upper wall of the cap body 11 as shown in FIG. 3. The packing 15 is fixed to the bottom surface 11b of the upper wall of the cap body 11 by an adhesive and is provided integrally with the cap body 11. Also, with the bottom surface 11b of the upper wall of the cap body 11 facing downward, the packing 15 is arranged above the retainer 12 and the plurality of fastening protrusions 13.

[0045] The packing 15 functions as a sealing portion that seals, for example, between the cap body 11 and the fuel filler opening FO of the fuel tank filler FTF. Specifically, the packing 15 is compressed, for example, between the bottom surface 11b of the upper wall of the cap body 11 and the tip annular surface TAF of the fuel tank filler FTF in a state where the fastening protrusion 13 of the fuel cap 1 engages with the fastening inclined surface TIF of the fuel tank filler FTF and abuts against the anti-rotation WS. Thereby, the packing 15 adheres tightly to the bottom surface 11b of the upper wall of the cap body 11 and the tip annular surface TAF, and seals between the cap body 11 and the fuel filler opening FO of the fuel tank filler FTF. Note that the fuel cap 1 may not have the packing 15. In this case, the bottom surface 11b of the upper wall of the cap body 11 can function as a sealing portion.

[0046] Hereinafter, the pressure release portion PR provided on the fastening inclined surface TIF of the fuel tank filler FTF shown in FIGS. 2 and 4 will be described in detail. The fuel tank FTK shown in FIG. 1 may be in a state where the internal pressure of the tank body TKB becomes higher than the atmospheric pressure and a force in the axial direction Da acts on the fuel cap 1 toward the outside of the tank body TKB. In a state where the internal pressure of the tank body TKB acts on the fuel cap 1 in this way, the pressure release portion PR is configured to regulate the movement of the fastening protrusion 13 of the fuel cap 1 and form a gap Ga between the fuel cap 1 and the fuel tank filler FTF.

[0047] Specifically, in a state where a force in the axial direction Da acts on the fuel cap 1 as described above, when the fuel cap 1 rotates in the second direction (relaxation direction) D2, which is the rotation direction opposite to the first direction D1, each fastening protrusion 13 moves from each fastening inclined surface TIF to the pressure release portion PR. The pressure release portion PR has, for example, an axial regulation surface MRA that engages the fastening protrusion 13 of the fuel cap 1 in this state and regulates the movement in the axial direction Da.

[0048] In the example shown in FIG. 4, the axial restraint surface MRA is, for example, an inclined surface PR1 having a larger inclination angle with respect to the tip annular surface TAF than the fastening inclined surface TIF of the fuel tank filler FTF. Note that the inclination angle of the inclined surface PR1 with respect to the tip annular surface TAF may be the same as the inclination angle of the fastening inclined surface TIF with respect to the tip annular surface TAF. In this case, the fastening inclined surface TIF and the inclined surface PR1 are provided continuously in a straight line. The boundary between the fastening inclined surface TIF and the inclined surface PR1 is, for example, the engagement start point ES where the fastening inclined surface TIF and the fastening protrusion 13 start to engage in a state where 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.

[0049] That is, the upper end 13t of the fastening protrusion 13 of the fuel cap 1 shown by the two-dot chain line in FIG. 4 contacts the fastening inclined surface TIF at the engagement start point ES when the fuel cap 1 is fastened to the fuel tank filler FTF with the sealing portion of the fuel cap 1 and the tip annular surface TAF in contact. After that, when the fuel cap 1 is further rotated in the first direction D1, each fastening protrusion 13 moves in the first direction D1 along the fastening inclined surface TIF and is pushed downward in the axial direction Da toward the inner side of the tank body TKB by the fastening inclined surface TIF and elastically deformed.

[0050] Further, the pressure release portion PR has a depth d capable of forming a gap Ga for releasing the internal pressure of the tank body TKB between the packing 15 of the fuel cap 1 shown by the two-dot chain line in FIG. 4 or the bottom surface 11b of the upper wall of the cap body 11 and the tip annular surface TAF of the fuel tank filler FTF. The depth d of this pressure release portion PR is the depth d in the axial direction Da with reference to the engagement start point ES of the fastening inclined surface TIF.

[0051] Here, the depth d of the pressure release portion PR is, for example, a depth d that can form an internal pressure release gap Ga of the tank body TKB in a state where no axial force Da acting outward from the fuel cap 1 acts on the tank body TKB. Specifically, the axial restraint surface MRA has, for example, a smaller axial distance Da from the tip annular surface TAF of the fuel tank filler FTF than the engagement start point ES of the fastening inclined surface TIF where the fastening protrusion 13 starts to engage in a state where the above-described force does not act. More specifically, the axial distance (height) from the tip annular surface TAF to the axial restraint surface MRA is, for example, smaller than the axial distance (height) from the tip annular surface TAF to the engagement start point ES.

[0052] Also, the pressure release portion PR has, for example, a rotation restraint portion AR that restricts the movement of the fastening protrusion 13 in the second direction D2, which is the rotation direction opposite to the first direction D1, in a state where an axial force Da acts on the fuel cap 1 as described above. The rotation restraint portion AR is provided on the rear side of the axial restraint surface MRA in the first direction D1, that is, adjacent to the axial restraint surface MRA in the second direction D2, and protrudes axially from the axial restraint surface MRA. As a result, the axial distance (height) from the tip annular surface TAF to the tip of the rotation restraint portion AR is, for example, larger than the distance (height) from the tip annular surface TAF to the axial restraint surface MRA.

[0053] Also, the axial distance (height) from the tip annular surface TAF to the tip of the rotation restraint portion AR is, for example, smaller than the axial distance (height) from the tip annular surface TAF to the engagement start point ES of the fastening inclined surface TIF. Here, the engagement start point ES is the position where the fastening protrusion 13 starts to engage with the fastening inclined surface TIF in a state where the above-described axial force Da does not act on the fuel cap 1 as described above. Also, in the examples shown in FIGS. 2 and 4, the pressure release portion PR is, for example, located in the second direction D2 when viewed from the engagement start point ES of the fastening inclined surface TIF.

[0054] Further, the pressure release portion PR has, for example, an inclined surface PR2 adjacent to the second direction D2, i.e., the rear side of the first direction D1 with respect to the inclined surface PR1 as the axial restraint surface MRA. This inclined surface PR2 is the wall surface on the front side of the rotation restraint portion AR in the first direction D1, and functions as a rotation restraint surface MRR that restricts the rotation of the fastening protrusion 13 in the second direction D2. In the example shown in FIG. 4, the inclination angle with respect to the tip annular surface TAF of the inclined surface PR2 is approximately 90°.

[0055] Hereinafter, based on the comparison with the conventional fuel tank cap described in the aforementioned Patent Document 1, the operation of the fuel tank FTK of the present embodiment will be described.

[0056] As described above, when the conventional fuel tank cap described in Patent Document 1 is loosened for removal in a state where the internal pressure of the fuel tank has risen, there is a risk of being blown away and lost by gases such as air ejected from the cap mounting port of the fuel tank.

[0057] On the other hand, the fuel tank FTK of the present embodiment includes a tank body TKB that stores fuel, a cylindrical fuel tank filler FTF provided on the tank body TKB, and a fuel cap 1 that closes the fuel filling port FO at the tip of the fuel tank filler FTF. The fuel cap 1 is fastened to the fuel tank filler FTF by rotating it in the first direction, which is the rotational direction around the axis of the fuel tank filler FTF. The fuel tank filler FTF includes a pressure release portion PR that restricts the movement of the fuel cap 1 in a state where a force in the axial direction Da of the fuel tank filler FTF acts on the fuel cap 1 due to the internal pressure of the tank body TKB, and forms a gap Ga between the fuel cap 1 and the fuel tank filler FTF.

[0058] With such a configuration, the fuel tank FTK of the present embodiment can remove the fuel cap 1 from the tip of the fuel tank filler FTF through the following procedure. First, rotate the fuel cap 1 in the second direction D2 opposite to the first direction D1. Then, pull up the fuel cap 1 in the axial direction Da of the fuel tank filler FTF. Thereby, the fuel cap 1 can be removed from the tip of the fuel tank filler FTF.

[0059] Here, in the fuel tank FTK, for example, due to the rise in the temperature of the air inside the fuel tank FTK with the fuel filler opening FO of the fuel tank filler FTF closed by the fuel cap 1, the expansion of the fuel volume due to the rise in the fuel temperature, or the reduction in the volume of the air portion inside the fuel tank FTK due to fueling with the fuel cap attached to the fuel tank FTK, the internal pressure may increase. In such a case, as described above, when the fuel cap 1 is rotated in the second direction D2, the movement of the fuel cap 1 in the second direction D2 is restricted by the pressure release portion PR provided in the fuel tank filler FTF.

[0060] 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 and form a gap Ga between the fuel cap 1 and the fuel tank filler FTF in a state where a force acts on the fuel cap 1 toward the outside of the tank body TKB. Therefore, with 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 restricted by the pressure release portion PR, a gap Ga is formed between the fuel cap 1 and the fuel tank filler FTF, and the gas inside the tank body TKB can be released into the atmosphere through the gap Ga.

[0061] As a result, the internal pressure of the tank body TKB can be reduced to approximately atmospheric pressure. Then, the fuel cap 1 is further rotated in the second direction D2 to lift it in the axial direction Da of the fuel tank filler FTF. Thereby, even when the internal pressure of the tank body TKB rises above atmospheric pressure, the internal pressure of the tank body TKB can be reduced to approximately atmospheric pressure while preventing the fuel cap 1 from being blown off, and the fuel cap 1 can be removed from the tip of the fuel tank filler FTF.

[0062] More specifically, in the fuel tank FTK of the present embodiment, the fuel tank filler FTF has a notch C, a fastening inclined surface TIF, and a pressure release portion PR. The notch C is formed in the tip annular surface TAF around the fuel filler opening FO. The fastening inclined surface TIF is provided inside the fuel filler opening FO adjacent to the notch C in the first direction D1. The fuel cap 1 has a cap body 11, a retainer 12, and a fastening protrusion 13. The cap body 11 covers the tip portion of the fuel tank filler FTF. The retainer 12 is an annular or disc-shaped member fixed to the bottom surface 11b of the upper wall of the cap body 11 facing the fuel filler opening FO. The fastening protrusion 13 is provided to protrude radially outward from the outer peripheral edge of the retainer 12, passes through the notch C in the axial direction Da of the fuel tank filler FTF, and engages with the fastening inclined surface TIF of the fuel tank filler FTF by rotating in the first direction D1. The pressure release portion PR of the fuel tank filler FTF is provided on the fastening inclined surface TIF. The pressure release portion PR is configured to restrict the movement of the fastening protrusion 13 in the state where the above-described force acts and form a gap Ga between the fuel cap 1 and the fuel tank filler FTF.

[0063] With such a configuration, the fuel tank FTK of this embodiment can remove the fuel cap 1 from the tip of the fuel tank filler FTF through the following procedure. First, rotate the cap body 11 of the fuel cap 1 in the second direction D2 opposite to the first direction D1, slide the plurality of fastening protrusions 13 of the fuel cap 1 along the fastening inclined surface TIF of the fuel tank filler FTF, and pass through the pressure release portion PR. Then, pass the plurality of fastening protrusions 13 of the fuel cap 1 through the plurality of notches C provided in the tip annular surface TAF of the fuel tank filler FTF. Thereby, the fuel cap 1 can be removed from the tip of the fuel tank filler FTF.

[0064] Here, as described above, the internal pressure of the fuel tank FTK may increase. In such a case, as described above, when the cap 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, on which the force in the axial direction Da acts under the internal pressure of the tank body TKB, slide along the fastening inclined surface TIF of the fuel tank filler FTF.

[0065] In such a case, in the fuel tank described in the above-mentioned conventional Patent Document 1, there is a possibility that the operation cap of the fuel tank cap receives the internal pressure, and each engaging convex portion of the latch piece attached to the operation cap passes through each notch formed in the cap mounting port of the fuel tank. As a result, the fuel tank cap may come off from the cap mounting port, and the fuel tank cap may be blown off by the gas ejected from the cap mounting port.

[0066] On the other hand, in the fuel tank FTK of this embodiment, when the cap body 11 is rotated in the second direction D2 opposite to the first direction D1 in a state where the force in the axial direction Da acts on the fuel cap 1, the fastening protrusion 13 moves 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 protrusion 13 in a state where the force in the axial direction Da acts, and form a gap Ga between the fuel cap 1 and the fuel tank filler FTF.

[0067] As a result, when the fastening protrusion 13 of the fuel cap 1 reaches the pressure release portion PR of the fuel tank filler FTF, a gap Ga is formed between the fuel cap 1 and the fuel tank filler FTF while the movement of the fuel cap 1 in the second direction D2 and the axial direction Da is restricted. As a result, it becomes possible to release the gas in the tank body TKB to the atmosphere through the gap Ga, and it is possible to reduce the internal pressure of the tank body TKB while preventing the fuel cap 1 from coming off from the fuel tank filler FTF.

[0068] 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 off by air or the like ejected from the fuel filling port FO even when the fuel cap 1 is removed while the internal pressure of the tank body TKB is increased.

[0069] Further, in the fuel tank FTK of the present embodiment, the pressure release portion PR of the fuel tank filler FTF has an axial restriction surface MRA that restricts the movement 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.

[0070] With such a configuration, when the fuel cap 1 fastened to the fuel tank filler FTF is rotated in the second direction D2 to move the fastening protrusion 13 to the pressure release portion PR while the internal pressure of the tank body TKB is increased, the movement in the axial direction Da is restricted by the axial 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 the direction opposite to the force in the axial direction Da can be applied to the fastening protrusion 13 from the axial restriction surface MRA which is an inclined surface PR1 intersecting the axial direction Da. Thereby, it is possible to prevent the fuel cap 1 from coming off from the fuel tank filler FTF when the internal pressure of the tank body TKB is released.

[0071] Further, in the fuel tank FTK of the present embodiment, the axial restraint surface MRA has a smaller axial distance Da from the tip annular surface TAF than the engagement start point ES of the fastening inclined surface TIF where 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.

[0072] With such a configuration, when the fuel cap 1 is rotated in the second direction D2 with the force in the axial direction Da acting thereon to move the fastening protrusion 13 to the axial restraint surface MRA, a gap Ga is formed between the tip annular surface TAF and the packing 15 or the bottom surface 11b of the upper wall of the cap body 11. In this case, the gap Ga can be formed without elastically deforming the fastening protrusion 13 in the axial direction Da, and the internal pressure of the tank body TKB can be reduced to approximately atmospheric pressure.

[0073] Further, in the fuel tank FTK of the present embodiment, the pressure release portion PR has a rotation restricting portion AR that restricts the movement of the fastening protrusion 13 in the second direction D2, which is the rotation direction opposite to the first direction D1, with the force in the axial direction Da acting thereon. The rotation restricting portion AR is provided adjacent to the axial restraint surface MRA in the second direction D2 and protrudes in the axial direction Da from the axial restraint surface MRA.

[0074] With such a configuration, when the fuel cap 1 is rotated in the second direction D2 with the force in the axial direction Da acting thereon to move the fastening protrusion 13 to the axial restraint surface MRA, the movement of the fastening protrusion 13 in the second direction D2 is restricted by the rotation restricting portion AR. Thereby, it is possible to prevent the fastening protrusion 13 from moving from the pressure release portion PR to the notch C when the internal pressure of the tank body TKB is released, and it is possible to prevent the fuel cap 1 from coming off the fuel tank filler FTF.

[0075] Further, in the fuel tank FTK of the present embodiment, the fastening inclined surface TIF has an engagement start point ES 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. And the distance in the axial direction Da from the tip annular surface TAF to the tip of the rotation restricting portion AR is smaller than the distance in the axial direction Da from the tip annular surface TAF to the engagement start point ES.

[0076] With such a configuration, when the fuel cap 1 descends in the axial direction Da of the fuel tank filler FTF after the internal pressure of the tank body TKB is released and the gap Ga for internal pressure release disappears, a gap in the axial direction Da is formed between the upper end 13t of the fastening protrusion 13 and the tip of the rotation restricting portion AR. In this state, by rotating the fuel cap 1 in the second direction D2, the fastening protrusion 13 is moved in the second direction D2 to pass below the rotation restricting portion AR, and the notch C of the fuel tank filler FTF can be reached. Then, by pulling up the fuel cap 1 in the axial direction Da and passing each fastening protrusion 13 through each notch C of the fuel tank filler FTF, the fuel cap 1 can be removed from the fuel tank filler FTF.

[0077] Also, in the fuel tank FTK of the present embodiment, when the rotation direction opposite to the first direction D1 is defined 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 protrusion 13 starts to engage in a state where the axial direction Da force does not act on the fuel cap 1.

[0078] With such a configuration, when the fuel cap 1 fastened to the fuel tank filler FTF is rotated in the second direction D2 in a state where the axial direction Da force does not act, the engagement between the fastening protrusion 13 and the fastening inclined surface TIF is released at the engagement start point ES. After that, when the fuel cap 1 is further rotated in the second direction D2, the fastening protrusion 13 passes below the pressure release portion PR and reaches the notch C, and the fuel cap 1 can be removed from the fuel tank filler FTF.

[0079] Also, when fastening the fuel cap 1 to the fuel tank filler FTF, each fastening protrusion 13 of the fuel cap 1 is aligned with each notch C of the fuel tank filler FTF and passed through in the axial direction Da. Then, when the fuel cap 1 is rotated in the first direction D1, the fastening protrusion 13 passes below the pressure release portion PR and engages with the fastening inclined surface TIF at the engagement start point ES.

[0080] After that, when the fuel cap 1 is further rotated in the first direction D1, each fastening protrusion 13 moves in the first direction D1 along each fastening inclined surface TIF, so that each fastening protrusion 13 elastically deforms in the axial direction Da toward the inside of the tank body TKB. As a result, the fuel cap 1 is fastened to the fuel tank filler FTF. Therefore, according to the above configuration, the fuel cap 1 can be attached to and detached from the fuel tank filler FTF without being affected by the pressure release portion PR.

[0081] The fuel cap 1 of the present embodiment further includes a disk cap 16 attached to the bottom surface 11b of the upper wall of the cap body 11 inside the retainer 12. This disk cap 16 has an outer diameter corresponding to the inner diameter of the fuel filling port FO and has a cylindrical guide portion 16g that engages inside the fuel filling port FO.

[0082] With such a configuration, when aligning the plurality of fastening protrusions 13 with the plurality of notches C provided on the tip annular surface TAF of the fuel tank filler FTF, the guide portion 16g of the disk cap 16 can be engaged with the fuel filling port FO. Thereby, the inclination of the central axis a of the fuel cap 1 with respect to the central axis A of the fuel tank filler FTF and the radial play of the cap body 11 are prevented, and the alignment can be facilitated. Therefore, the attachment and detachment of the fuel cap 1 to and from the fuel tank filler FTF can be facilitated.

[0083] As described above, according to the present embodiment, even if the fuel cap 1 is removed while the internal pressure of the tank body TKB is increased, it is possible to provide a fuel tank FTK that can prevent the fuel cap 1 from being blown off by the gas ejected from the fuel filler port FO.

[0084] [Embodiment 2] Hereinafter, referring to FIGS. 1 to 3 of the above-described Embodiment 1 and referring to FIG. 5, Embodiment 2 of the fuel tank according to the present disclosure will be described. The configuration of the pressure release portion PR of the fuel tank FTK of the present embodiment is different from that of the fuel tank FTK of the above-described Embodiment 1. Since other configurations of the fuel tank FTK in the present embodiment are the same as those of the fuel tank FTK of the above-described Embodiment 1, the same reference numerals are given to the same parts and the description thereof is omitted.

[0085] FIG. 5 is a diagram corresponding to FIG. 4 showing Embodiment 2 of the fuel tank according to the present disclosure. The fuel tank FTK of the present embodiment has a pressure release portion PR provided on the fastening inclined surface TIF of the fuel tank filler FTF, similarly to the fuel tank FTK of the above-described Embodiment 1.

[0086] In the fuel tank FTK of the present embodiment, the pressure release portion PR is located, for example, in the first direction D1 when viewed from the engagement start point ES of the fastening inclined surface TIF. Here, the engagement start point ES of the fastening inclined surface TIF is the 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 described above does not act on the fuel cap 1, similarly to the fuel tank FTK in the above-described Embodiment 1.

[0087] Also, in the fuel tank FTK of the present embodiment, the depth d of the pressure release portion PR may be, for example, a depth d that can form a gap Ga for releasing the internal pressure of the tank body TKB in a state where a force in the axial direction Da directed outward of the tank body TKB acts on the fuel cap 1. Specifically, each fastening protrusion 13 of the fuel cap 1 may be configured to elastically deform in the axial direction Da in the pressure release portion PR to form a gap Ga for releasing the internal pressure in a state where the force in the axial direction Da described above acts.

[0088] In other words, the depth d of the pressure release portion PR may be, for example, a depth d at which no axial force Da acting outward from the tank body TKB is applied to the fuel cap 1 and no gap Ga for releasing the internal pressure of the tank body TKB is formed. Note that the amount of elastic deformation of the fastening protrusion 13 or the size of the gap Ga for releasing the internal pressure during internal pressure release can be appropriately set according to the assumed internal pressure of the tank body TKB.

[0089] Also, in the fuel tank FTK of the present embodiment, the pressure release portion PR includes an axial regulation surface MRA and a rotation regulation surface MRR, similar to the fuel tank FTK of the aforementioned Embodiment 1. Note that in the fuel tank FTK of the present embodiment, the axial regulation surface MRA is a flat surface PR3 that is substantially parallel to the tip annular surface TAF of the fuel tank filler FTF. In other words, the axial regulation surface MRA of the pressure release portion PR is, for example, a flat surface perpendicular to the axial direction Da of the fuel tank filler FTF.

[0090] Also, in the fuel tank FTK of the present embodiment, the rotation regulation surface MRR is an inclined surface PR2 that is inclined so as to increase the axial distance (height H) from the tip annular surface TAF in the second direction D2 opposite to the first direction D1 of the fuel cap 1. The inclination angle of the inclined surface PR2 with respect to the tip annular surface TAF is, for example, an acute angle less than 90°. Further, the pressure release portion PR includes, for example, an inclined surface PR1 that is inclined so as to increase the axial distance (height H) from the tip annular surface TAF in the first direction D1 of the fuel cap 1. The inclination angle of the inclined surface PR1 with respect to the tip annular surface TAF is, for example, an acute angle less than 90°.

[0091] Also in the fuel tank FTK of the present embodiment, when the cap body 11 is rotated in the second direction D2 opposite to the first direction D1 with the force in the axial direction Da acting on the fuel cap 1, the fastening protrusion 13 moves from the fastening inclined surface TIF to the pressure release portion PR. This pressure release portion PR is configured to regulate the movement of the fastening protrusion 13 in a state where the force in the axial direction Da acts thereon, and to form a gap Ga between the fuel cap 1 and the fuel tank filler FTF, in the same manner as the pressure release portion PR of the first embodiment described above.

[0092] Therefore, also in the present embodiment, similar to the first embodiment described above, it is possible to provide a fuel tank FTK that can prevent the fuel cap 1 from being blown off by the gas ejected from the fuel filling port FO even when the fuel cap 1 is removed in a state where the internal pressure of the tank body TKB has risen.

[0093] Further, in the fuel tank FTK of the present embodiment, in a state where the force in the axial direction Da acts on the fuel cap 1, the fastening protrusion 13 of the fuel cap 1 can be elastically deformed in the axial direction Da at the pressure release portion PR of the fuel tank filler FTF to form a gap Ga.

[0094] With such a configuration, when the gas in the tank body TKB is released from the gap Ga and the internal pressure of the tank body TKB decreases, the force in the axial direction Da acting on the fuel cap 1 decreases, and the amount of elastic deformation of the fastening protrusion 13 decreases. As a result, before the internal pressure of the tank body TKB drops to atmospheric pressure, the gap Ga between the fuel cap 1 and the tip annular surface TAF of the fuel tank filler FTF disappears, and the packing 15 or the bottom surface 11b of the upper wall of the cap body 11 is pressed against the tip annular surface TAF. Therefore, it is possible to reduce the volume of the gas released from the fuel tank filler FTF when the fuel cap 1 is loosened and the fastening protrusion 13 is moved to the pressure release portion PR.

[0095] Also, in the fuel tank FTK of the present embodiment, the axial regulation surface MRA of the pressure release portion PR is a flat surface PR3 perpendicular to the axial direction Da of the fuel tank filler FTF.

[0096] With such a configuration, when the cap body 11 is rotated in the second direction D2 with the force in the axial direction Da acting on the fuel cap 1 and the fastening protrusion 13 is moved to the flat surface PR3 of the pressure release portion PR, it is possible to prevent a component force in the second direction D2 from acting on the fastening protrusion 13. As a result, it is possible to prevent each fastening protrusion 13 from reaching each notch C of the fuel tank filler FTF in a state where the force in the axial direction Da acts on the fuel cap 1, and it is possible to more reliably prevent the fuel cap 1 from coming off from the fuel tank filler FTF.

[0097] Also, in the fuel tank FTK of the present embodiment, the pressure release portion PR is located in the first direction D1 when viewed from the engagement start point ES of the fastening inclined surface TIF. Here, the engagement start point ES is the point at which the fastening protrusion 13 starts to engage with the fastening inclined surface TIF in a state where the force in the axial direction Da does not act on the fuel cap 1 as described above.

[0098] With such a configuration, the fuel tank FTK of the present embodiment can rotate the fuel cap 1 in the second direction D2 to move each fastening protrusion 13 to the pressure release portion PR provided on each fastening inclined surface TIF of the fuel tank filler FTF as described above. Then, after forming a gap Ga between the fuel cap 1 and the fuel tank filler FTF to reduce the internal pressure of the tank body TKB, when the fuel cap 1 is further rotated in the second direction D2, each fastening protrusion 13 moves in the second direction D2 and engages with each fastening inclined surface TIF again. After that, when the fuel cap 1 is further rotated in the second direction D2, each fastening protrusion 13 moves in the second direction D2, passes through the engagement start point ES, and reaches the notch C, so that the fuel cap 1 can be removed from the fuel tank filler FTF.

[0099] Here, as described above, the pressure release portion PR of the present embodiment has an inclined surface PR2 that is inclined at an angle of less than 90° with respect to the tip annular surface TAF such that the axial distance Da from the tip annular surface TAF increases in the second direction D2. With such a configuration, after the internal pressure of the tank body TKB is released, the fuel cap 1 can be rotated in the second direction D2 to move each fastening protrusion 13 along each inclined surface PR2. As a result, each fastening protrusion 13 of the fuel cap 1 can be engaged with each fastening inclined surface TIF adjacent to the second direction D2 of each pressure release portion PR provided in the fuel tank filler FTF.

[0100] Further, the inclined surface PR2 of the pressure release portion PR also functions as a rotation restricting surface MRR that restricts the rotation of each fastening protrusion 13 in the second direction D2 in a state where the axial force Da acts on the fuel cap 1. With such a configuration, in a state where the axial force Da acts on the fuel cap 1, each fastening protrusion 13 is prevented from reaching each notch C of the fuel tank filler FTF, and it is possible to more reliably prevent the fuel cap 1 from coming off the fuel tank filler FTF.

[0101] [Embodiment 3] Hereinafter, referring to FIGS. 1 to 3 of the above-described Embodiment 1 and referring to FIG. 6, Embodiment 3 of the fuel tank according to the present disclosure will be described. The fuel tank FTK of the present embodiment is different from the fuel tank FTK of the above-described Embodiment 2 in the configuration of the pressure release portion PR. Since the other configurations of the fuel tank FTK in the present embodiment are the same as those of the fuel tank FTK of the above-described Embodiment 2, the same reference numerals are given to the same parts and the description thereof is omitted.

[0102] FIG. 6 is a diagram corresponding to FIG. 4 showing Embodiment 3 of the fuel tank according to the present disclosure. Similar to the fuel tank FTK of the aforementioned Embodiment 2, the fuel tank FTK of the present embodiment has a pressure release portion PR provided on the fastening inclined surface TIF of the fuel tank filler FTF. Further, similar to the pressure release portion PR of the aforementioned Embodiment 2, the pressure release portion PR of the present embodiment has an inclined surface PR1 and an axial direction regulating surface MRA which is a flat surface PR3.

[0103] On the other hand, different from the pressure release portion PR of the aforementioned Embodiment 2, the pressure release portion PR of the present embodiment does not have a rotation regulating surface MRR which is an inclined surface PR2. Further, in the fuel tank FTK of the present embodiment, each fastening protrusion 13 of the fuel cap 1 starts engaging with the inclined surface PR1 at the engagement start point ES on the inclined surface PR1 of the pressure release portion PR, for example, when the fuel cap 1 is fastened to the fuel tank filler FTF.

[0104] Note that the pressure release portion PR of the present embodiment may be provided in the second direction when viewed from the engagement start point ES on the fastening inclined surface TIF, as shown by a dashed line in FIG. 6, for example. In this case, the pressure release portion PR can include, for example, an axial direction regulating surface MRA which is a flat surface PR3 and an inclined surface PR4. The inclined surface PR4 is provided at the front end of the flat surface PR3 in the first direction D1, for example, and is formed in a stepped shape having an inclination angle of approximately 90° with respect to the tip annular surface TAF.

[0105] Also in the fuel tank FTK of the present embodiment, when the cap body 11 is rotated in the second direction D2 opposite to the first direction D1 with the force in the axial direction Da acting on the fuel cap 1, the fastening protrusion 13 moves from the fastening inclined surface TIF to the pressure release portion PR. Similar to the pressure release portion PR of the aforementioned Embodiment 2, the pressure release portion PR is configured to regulate the movement of the fastening protrusion 13 with the force in the axial direction Da acting thereon and form a gap Ga between the fuel cap 1 and the fuel tank filler FTF.

[0106] More specifically, as described above, the fastening protrusion 13 that has moved from the fastening inclined surface TIF to the pressure release portion PR is restricted from moving in the axial direction Da by the axial direction regulating surface MRA, which is a flat surface PR3 perpendicular to the axial direction Da of the fuel tank filler FTF. Further, when the force in the axial direction Da acts on the fuel cap 1, a perpendicular resistance force acts between each axial direction regulating surface MRA and each fastening protrusion 13, generating a frictional force that prevents each fastening protrusion 13 from moving in the second direction D2.

[0107] As a result, it is possible to prevent each fastening protrusion 13 of the fuel cap 1 from reaching each notch C of the fuel tank filler FTF, and thus prevent the fuel cap 1 from coming off the fuel tank filler FTF. Therefore, also in the present embodiment, as in the aforementioned Embodiment 2, even if the fuel cap 1 is removed while the internal pressure of the tank body TKB has increased, it is possible to provide a fuel tank FTK that can prevent the fuel cap 1 from being blown off by the gas ejected from the fuel filling port FO.

[0108] As described above, also in the present embodiment, it is possible to provide a fuel tank FTK that can prevent the fuel cap 1 from being blown off by air or the like ejected from the fuel filling port FO even if the fuel cap 1 is removed while the internal pressure of the tank body TKB has increased.

[0109] As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments. Various modifications, substitutions, etc. can be applied to the above-described embodiments without departing from the scope of the present invention. Also, the features described separately can be combined as long as no technical contradiction occurs.

Explanation of Reference Numerals

[0110] 1 Fuel cap 11 Cap body 11b Bottom surface of the upper wall 12 Retainer 13 Fastening protrusion AR Rotation restricting portion C Notch D1 First Direction D2 Second Direction Da Axial Direction ES Engagement Start Point FO Fuel Filling Port FTF Fuel Tank Filler FTK Fuel Tank Ga Gap H Height MRA Axial Direction Regulation Surface PR Pressure Release Port PR3 Flat Surface TAF Tip Annular Surface TIF Tightening Inclined Surface TKB Tank Body

Claims

1. A fuel tank comprising: a tank body for storing fuel; a cylindrical fuel tank filler provided on the tank body; and a fuel cap that is fastened to the fuel tank filler by rotating in a first direction around the axis of the fuel tank filler to close a fuel filling port at the tip of the fuel tank filler. The fuel tank filler includes a pressure release portion that restricts movement of the fuel cap in a state where an axial force of the fuel tank filler acts on the fuel cap due to the internal pressure of the tank body, thereby forming a gap between the fuel cap and the fuel tank filler. Fuel tank.

2. The fuel tank filler has a notch formed in a tip annular surface around the fuel filling port, and a fastening inclined surface provided inside the fuel filling port adjacent to the notch in the first direction. The fuel cap has a cap body that covers the tip of the fuel tank filler, an annular retainer fixed to the bottom surface of the upper wall of the cap body facing the fuel filling port, and a fastening protrusion provided to protrude radially outward from the outer peripheral edge of the retainer, passing through the notch in the axial direction of the fuel tank filler, and engaging with the fastening inclined surface by rotating in the first direction. The pressure release portion is provided on the fastening inclined surface and is configured to restrict movement of the fastening protrusion in a state where the force acts, thereby forming the gap between the fuel cap and the fuel tank filler. The fuel tank according to claim 1.

3. The fastening protrusion is configured to elastically deform in the axial direction at the pressure release portion in a state where the force acts, thereby forming the gap. The fuel tank according to claim 2.

4. The pressure release portion has an axial restriction surface that restricts axial movement by engaging the fastening protrusion in a state where the force acts. The fuel tank according to claim 2.

5. The axial restriction surface has an axial distance from the tip annular surface that is smaller than an engagement start point of the fastening inclined surface where the fastening protrusion starts to engage in a state where the force does not act. The fuel tank according to claim 4.

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

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

8. The fastening inclined surface has an engagement start point at which the fastening protrusion starts to engage in a state where the force is not acting. The axial distance from the tip annular surface to the tip of the rotation restricting portion is smaller than the axial distance from the tip annular surface to the engagement start point. The fuel tank according to claim 7.

9. The pressure release portion is located in the first direction when viewed from the engagement start point of the fastening inclined surface at which the fastening protrusion starts to engage in a state where the force is not acting. The fuel tank according to claim 2.

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

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