FUEL TANK

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on and claims priority under 35 U.S.C. 119 to Japanese Patent Application No. 2007-112622, filed on Apr. 23, 2007, the entire contents of which is hereby incorporated by reference and should be considered part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fuel tank mounted on an apparatus, such as an engine generator or a general-purpose engine, that carries an engine thereon.

2. Description of the Related Art

An example of a fuel tank mounted on a general-purpose engine is described in Japanese Publication No. JP-2005-163688. Such a fuel tank includes a tank body for storing fuel therein, a fuel inlet provided on a top face of the tank body and projecting upwardly from the outer surface of the fuel tank, and a fuel cap removably installed on the fuel inlet. However, undesirably, the fuel cap is to be fastened with little air left inside the fuel tank when fuel is filled to an upper end of the fuel inlet.

In a general-purpose engine having such a fuel tank, the fuel tank is positioned in the vicinity of the engine for compactness. In a sound-insulating engine generator having such a fuel tank, the fuel tank is positioned in the vicinity of the engine, and a casing of the generator is formed by attaching panels to a frame. Accordingly, exhaust heat Produced from the engine and the like can increase a temperature of the fuel in the fuel tank, resulting in an undesired rise of a liquid level in the fuel tank.

SUMMARY OF THE INVENTION

In view of the circumstances noted above, one aspect of the present invention is to provide a fuel tank capable of suppressing a rise of a liquid level in a fuel tank due to a temperature increase in the fuel tank caused by exhaust heat generated by an engine and the like.

In accordance with one aspect of the present invention, a fuel tank is provided. The fuel tank comprises a tank body configured for storing fuel therein, with a fuel inlet provided on a top face of the tank body and projecting upwardly therefrom. The fuel tank also comprises a fuel cap removably coupleable onto the fuel inlet, the fuel cap comprising a hollow neck portion configured to project into the fuel inlet when the fuel cap is installed on the fuel inlet. A chamber in the neck portion has an opening in a lower end portion of the chamber and a communicating passage in an upper portion of the chamber, the upper portion of the chamber of the neck placed in communication with an interior of the tank body via the communicating passage when the fuel cap is installed on the fuel inlet so that a fuel level within the chamber of the neck portion and a fuel level in the tank body outside the neck portion are equalized when the fuel cap is coupled to the fuel tank, thereby inhibiting a rise in fuel level in the fuel tank body.

In accordance with another aspect of the present invention, an engine generator having an engine and a generator is provided. The engine generator comprises a fuel tank with a tank body configured for storing fuel therein, and a fuel inlet provided on a top face of the tank body and projecting upwardly therefrom. The fuel tank also comprises a fuel cap removably coupleable onto the fuel inlet, the fuel cap comprising a hollow neck portion configured to project into the fuel inlet when the fuel cap is installed on the fuel inlet. A chamber in the neck portion has an opening in a lower end portion of the chamber and a communicating passage in an upper portion of the chamber, the upper portion of the chamber of the neck placed in communication with an interior of the tank body via the communicating passage when the fuel cap is installed on the fuel inlet so that a fuel level within the chamber of the neck portion and a fuel level in the tank body outside the neck portion are equalized when the fuel cap is coupled to the fuel tank, thereby inhibiting a rise in fuel level in the fuel tank body.

In accordance with yet another aspect of the present invention, a fuel tank is provided comprising a tank body configured for storing fuel therein, a fuel inlet provided on a top face of the tank body and projecting upwardly therefrom. The fuel tank further comprises a fuel cap removably coupleable onto the fuel inlet, the fuel cap comprising a neck portion configured to project into the fuel inlet when the fuel cap is installed on the fuel inlet, the neck portion comprising means inhibiting a rise of a liquid level due to an increase in temperature in the fuel tank when the fuel cap is coupled to the fuel inlet.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention will now be described in connection with preferred embodiments of the invention, in reference to the accompanying drawings. The illustrated embodiments, however, are merely examples and are not intended to limit the invention. The drawings include the following 11 figures.

FIG. 1 is a plan view of one embodiment of a sound-insulation-type engine generator with a fuel tank cut away, as viewed from a top face side of the generator.

FIG. 2 is a front view of the sound-insulation-type engine generator of FIG. 1, with an engine cut away.

FIG. 3 is a cross-sectional view showing a fuel cap being installed on a fuel inlet.

FIG. 4 is a plan view of the fuel inlet.

FIG. 5 is a cross-sectional view of the fuel cap.

FIG. 6 is a plan view of a neck of the fuel cap.

FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 6.

FIG. 8 is an enlarged side view of a groove in the neck.

FIG. 9 is a cross-sectional view of the fuel cap and the fuel inlet in a state in which the fuel cap is removed and fuel is oversupplied to overflow over an upper end of the fuel inlet.

FIG. 10 is a cross-sectional view of the fuel cap and the fuel inlet in a state in which the fuel cap is being installed.

FIG. 11 is a cross-sectional view of the fuel cap and the fuel inlet in a state in which the fuel cap has been installed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description, terms of orientation such as “front,” “rear,” “left” and “right” are used herein to simplify the description of the context of the illustrated embodiments. Likewise, terms of sequence, such as “first” and “second,” are used to simplify the description of the illustrated embodiments. Because other orientations and sequences are possible, however, the present invention should not be limited to the illustrated orientation. Those skilled in the art will appreciate that other orientations of the various components described above are possible.

An embodiment of the invention will be described below. This embodiment is one of the most preferable embodiments of the invention and does not limit the scope of the invention.

FIGS. 1 and 2 show one embodiment of a sound-insulation-type engine generator 10 with a fuel tank 27 mounted thereon. FIG. 1 is a plan view of the sound-insulation-type engine generator 10 with the fuel tank 27 cut away, as viewed from a top face side of the generator 10. FIG. 2 is a front view of the sound-insulation-type engine generator 10 with an engine cut away. In this embodiment, for clarity, plan views and the front view are those taken viewing the sound-insulation-type engine generator 10 from its rear, and left, right, front, and rear directions are defined accordingly.

A sound-insulating casing K of the sound-insulation-type engine generator 10 can have a rounded box-like shape, and include a front frame 21 and a rear frame 22. The front and rear frames 21 and 22 can be formed in a frame-like shape with a metal and spaced from each other in a fore-and-aft direction. A molded-resin front panel 13 and a rear panel 17 can be provided in the front frame 21 and the rear frame 22, respectively. The rear panel 17 can include a control board thereon. Handle-attaching portions 21a and 21b can project upwardly on the left and right sides at the top of the front frame 21, respectively, and handle-attaching portions 22a and 22b can project upwardly on the left and right sides at the top of the rear frame 22, respectively. Both ends of a handle 19a are attached to the handle-attaching portions 21a and 22a, respectively, and both ends of a handle 19b are attached to the handle-attaching portions 21b and 22b, respectively.

Legs 21c and 21d can be provided on the left and right sides at a bottom of the front frame 21, respectively, and legs 22c and 22d can be provided on the left and right sides at a bottom of the rear frame 22, respectively. The legs 21c and 21d, and the legs 22c and 22d may be formed integrally with the bottoms of the front frame 21 and the rear frame 22, respectively, or formed independently and then attached thereto.

A top cover 14, a right-side cover 15, a left-side cover 16, and a bottom cover 18 can be provided between the front frame 21 and rear frame 22. Each of the front panel 13, the rear panel 17, the top cover 14, the right-side cover 15, the left-side cover 16 and the bottom cover 18, in one embodiment, can be made of resin. The sound-insulation-type engine generator 10 can be carried by holding the handles 19a and 19b attached to the handle-attaching portions 21a and 22a, and 21b and 22b, respectively.

The top cover 14 can be attached to upper edges of the front and rear frames 21 and 22 and extend therebetween and form a top face of the sound-insulation-type engine generator 10. The top cover 14 can have a curved surface extending in a left-and-right direction (hereinafter referred to as a “lateral direction”) and protruding upward at its center. A seal 90 can be attached to a substantial portion of the top cover 14 (e.g., a center portion). A fuel inlet 27a projects upwardly from a fuel inlet insertion receptacle 90d formed in the seal 90.

An upwardly projecting rib 90b can be formed on a peripheral edge of the seal 90. The rib 90b can slope downwardly toward the right so that, for example, when fuel accidentally overflows out during fueling via the fuel supply inlet 27a, the rib 90b guides and discharges the overflowed fuel rightward. An inspection window 91 can be provided in the seal 90 to allow monitoring a result of detection performed by a fuel level sensor 92 through the inspection window 91.

The right-side and left-side covers 15 and 16 can be respectively attached to opposite side edges of the front and rear frames 21 and 22 to form side faces of the sound-insulation-type engine generator 10. A plurality of air inlet ports 15a, which can extend laterally and be aligned vertically, can be formed in a portion lower than a substantial center of the right-side cover 15. The left-side cover 16 can have air vents 16a, each of which can be a laterally-extending air-vent slit, and an opening 16b, which can have a circular shape.

An engine 31 and a generator 32 can be juxtaposed in the sound-insulation-type engine generator 10. A suction fan 31d in the engine 31 can suck outside air into the sound-insulating casing K through the air-intake ports 15a in the right-side cover 15 to cool the engine 31. The air can thereafter be discharged through the air vents 16a in the left-side cover 16 to the outside.

An air cleaner 35 can be positioned in the sound-insulation-type engine generator 10, for example, at a substantially vertical center of a right front portion of the engine generator 10. A carburetor 36 can be positioned adjacent to the air cleaner 35 to be closer to the engine 31 than the air cleaner 35. The air cleaner 35 can in one embodiment be positioned on an air-intake side of the engine 31, receives the outside air sucked into the inside of the sound-insulating casing K by the suction fan 31d, cleans the air, and supplies the cleaned air to the carburetor 36.

Fuel supplied from the fuel tank 27 to the carburetor 36 is mixed with air supplied through the air cleaner 35 to the carburetor 36. The resultant air-fuel mixture is supplied to the engine 31 through an intake pipe 37. The engine 31 includes at least one spark plug 44 that ignites the air-fuel mixture supplied from the carburetor 36 to produce combustion in the engine 31, thereby running the engine 31. Blow-by gas fills the inside of a cylinder-head cap 53e of a cylinder head 53 returns to the air cleaner 35 through a blow-by gas pipe 53f, where it is mixed with air, and is subjected to re-combustion to prevent release of the blow-by gas into the atmosphere.

A muffler 39 can be provided on an exhaust side of the engine 31 with an exhaust pipe 38 therebetween. Exhaust gas discharged from the engine 31 is muffled through the muffler 39, and then discharged out of the engine generator 10 through the opening 16b in the left-side cover 16 via an exhaust port facing the outside.

The generator 32 can be positioned in the vicinity of the left-side cover 16 in the sound-insulation-type engine generator 10. The fuel tank 27 can be located above the engine 31 and include a mounting portion 27b. The fuel tank 27 can be fastened via the mounting portion 27b to a fuel-tank mounting plate 33, which is attached to the front and rear frames 21 and 22, with a bolt 34.

In the illustrated embodiment, mounting plate 40 is attached to a lower portion in the sound-insulation-type engine generator 10 by, for example, fitting insertion bosses 40a and 40b of the mounting plate 40 into receptacle bosses 18a and 18b that projects upward from the bottom cover 18. A canister mounting bracket 41 includes legs 41a and 41b. The canister mounting bracket 41 can be fastened via one leg 41a to the receptacle boss 18a and the insertion boss 40a with a bolt 42 and a nut 43, and fastened via the other leg 41a to the receptacle boss 18b and the insertion boss 40b via a positioning member with a bolt 45 and a nut 46. A canister 50 can be fixed to the canister mounting bracket 41 with a belt 51.

A downstream end 52a of a breather pipe 52 can be connected to the canister 50, and an upstream end 52b of the breather pipe 52 can be connected to the fuel inlet 27a of the fuel tank 27 to guide blow-by gas produced in the fuel tank 27 to the canister 50. An upstream end 55a of an air release pipe 55 is connected to the canister 50, and a downstream end 55b of the air release pipe 55 is connected to an opening 18c in the bottom cover 18, thereby opening the canister 50 to the atmosphere. Alternatively, an opening defined in the canister 50 may be open to the inside of the sound-insulation-type engine generator 10 instead of providing the air release pipe 55 and the opening 18c in the bottom cover 18.

With continued reference to FIG. 2, first end 56a of a purge pipe 56 is connected to the canister 50, and a second end 56b of the purge pipe 56 is connected to the blow-by gas pipe 53f to bring the canister 50 into communication with the suction side through the purge pipe 56 and the blow-by gas pipe 53f. Hence, air drawn due to operation of the engine 31 causes evaporative fuel in the canister 50 to be sucked into the suction side, which brings fuel adsorbed onto the canister 50 back to the suction side of the engine 31.

The upstream end 52b of the breather pipe 52 can be fastened to a mounting portion 27c of the fuel tank 27 with a fitting 57 therebetween with, for example, a bolt 58. The downstream end 52a can be integrated with the first end 56a of the purge pipe 56 by a fitting 59.

Next, the fuel tank 27 will be described with reference to FIGS. 3 to 8. FIG. 3 is a cross-sectional view showing the fuel cap 28 and the fuel inlet 27a in a state in which the fuel cap 28 is being installed on the fuel inlet 27a. FIG. 4 is a plan view of the fuel inlet 27a. FIG. 5 is a cross-sectional view of the fuel cap 28. FIG. 6 is a plan view of a neck 28b of the fuel cap 28. FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 6. FIG. 8 is an enlarged side view of a groove 28b12 in the neck 28b.

In the illustrated embodiment, fuel tank 27 includes a tank body 27A for storing fuel therein and the fuel inlet 27a provided on a top face of the tank body 27A and projecting upward. The tank body 27A and the fuel inlet 27a can be made of e.g. resin, and in one embodiment the fuel inlet 27 can be fixed to the fuel tank 27 with an adhesive or a like. In one embodiment, the fuel inlet 27a is removably attached to tank body 27a. The fuel inlet 27a can have a cylindrical shape with a male thread 27a1 cut in an upper periphery. The fuel inlet 27a can include, on its lower portion, a flange 27a2 that is fixed to a recess 27A1 in the tank body 27A.

A recess 27A2 is defined in the tank body 27A at a position in the vicinity of the fuel inlet 27a. A fuel level sensor 92 can be attached to a receptacle ring 92a, which can be fixed to the recess 27A2. The fuel level sensor 92 can include a detection-result indicator 92b, a rod 92c, a sensing section 92d, and the like. The detection-result indicator 92b can be positioned to conform to the inspection window 91 in the seal 90. A remaining amount of fuel detected by the sensing section 92d is preferably displayed on the detection-result indicator 92b, which can be monitored through the inspection window 91.

An engaging groove 90a can be defined in the periphery of a lower portion of the seal 90. An inner edge of an opening 14K in the top cover 14 can be fitted into the engaging groove 90a to thereby attach the seal 90 to the top cover 14. A space 93 is defined between the seal 90 and the top cover 14, and the tank body 27A.

An inwardly-projecting strainer receptacle 27a3 is formed in the fuel inlet 27a at a portion lower than its axial center. A strainer 80 can be inserted into the strainer receptacle 27a3 from above so that a collar 80a, which is formed on an upper periphery of the strainer 80, engages with a step portion 27a31 formed in an upper-end inner circumference of the strainer receptacle 27a3. Thus, the strainer 80 can be removably mounted in the strainer receptacle 27a.

The fuel inlet 27a includes a passage forming portion 27a4 at a position higher than the strainer receptacle 27a3. The passage forming portion 27a4, a portion of which projects inwardly, extends axially. An upper end 27a41 of the passage forming portion 27a4 is lower than an upper end 27a5 of the fuel inlet 27a by a distance D1.

The fuel inlet 27a can include, in its lower portion, a pipe receiving boss 27a6. The upstream end 52b of the breather pipe 52 can sheathe the pipe receiving boss 27a6 therein to attach the breather pipe 52 to the fuel inlet 27a. In the illustrated embodiment, a discharging passage 27a7 extends from the passage forming portion 27a4 to the pipe receiving boss 27a6. An obstacle 81 can be inserted into an inlet at the upper-end of the discharging passage 27a7. A pair of small inlet passages 27a71 (hereinafter simply referred to as “the inlet passage 27a71”) can be formed on opposite sides of the obstacle 81 (See FIG. 4). The obstacle 81 can be made of rubber and easily installed in the upper-end inlet of the discharging passage 27a7 by being inserted thereinto.

As described above, the obstacle 81 can be inserted into the discharging passage 27a7 so that the inlet passage 27a71 has a smaller cross-sectional area than a portion of the discharging passage 27a7 not sheathing the obstacle 81. This structure inhibits evaporative fuel, which is produced in the tank body 27A and directed to the canister 50 via the breather pipe 52, from overflowing from the fuel inlet 27a into the canister 50 via the discharging passage 27a7 and the breather pipe 52.

A chain holder 80b can be formed in a portion of the collar 80a of the strainer 80. One end 83a of a chain 83 can be inserted into a hole 80b1 in the chain holder 80b to thus be engaged therein. The chain 83 can be further inserted into a chain receiving hole 27a8 defined in the strainer receptacle 27a3, to thus be attached thereto. The other end 83b of the chain 83 can be attached to the fuel cap 28.

The fuel cap 28 includes a cap body 28a and the neck 28b. The neck 28b can be fixed to the cap body 28a with its upper end face joined to a bottom face of the cap body 28a. The cap body 28a can include a dish-shaped cap casing 28a1, a bowl-shaped support 28a2, in which a female thread 28a21 is cut, a neck seat 28a3, to which the neck 28b is attached, and the like. The cap casing 28a1, the bowl-shaped support 28a2, and the neck seat 28a3 can each be made of resin.

When the support 28a2 is pushed into the inside of the cap casing 28a1, an engaging pawl 28a11 formed on an inner wall of an opening in the cap casing 28a1 can engage with an engaging pawl 28a21 formed on an outer wall of an opening in the support 28a2. Hence, the support 28a2 can be mounted in the cap casing 28a1. A protrusion 28a31 formed at an axial center of the neck seat 28a3 can be inserted into a boss 28a12 of the cap casing 28a1 through a mounting hole 28a22 in the support 28a2. Bolts 70 can be screwed to the support 28a2 through mounting holes 28b11 in a collar 28b1 of the neck 28b and then through mounting holes 28a39 in bolt receiving portions 28a38 of the neck seat 28a3. Hence, the bolt receiving portions 28a38 of the neck seat 28a3 and the collar 28b1 of the neck 28b can be fastened to the support 28a2 with the bolts 70. A female thread 28a41 can be formed in an inner side wall near an open end of the support 28a2. An annular seal 61 can be interposed between an outer-ring tip end 28a32 of the neck seat 28a3 and an inner top face 28a23 of the support 28a2. A mounting space K into which a leading end of the fuel inlet 27a is to be inserted is defined between the female thread 28a41 of the support 28a2 and the periphery of the neck seat 28a3.

The neck 28b can be a hollow cylinder formed such that a lower portion 28b2 of the neck 28b has a larger cross-sectional area than an upper portion 28b3. A chain receptacle 28b4, of which connector 28b41 can be formed integrally with the lower portion 28b2, can be formed integrally with the lower portion 28b2. A mounting boss 28b42 can be positioned in a center of the connector 28b41 and formed integrally therewith. The chain 83 can be attached to the mounting boss 28b42 at the other end 83b. A plurality of (in this embodiment, four) openings 28b5, through which a chamber 28b6 is in communication with a bottom opening 28b7, can be defined in the connector 28b41. The bottom opening 28b7 is arranged coaxially with the neck 28b. However, a plurality of openings may alternatively be defined in a side wall or a like of the lower portion 28b2 of the neck 28b.

The mounting holes 28b11 can be provided at three positions in the collar 28b1 of the neck 28b. A groove 28b12 having a small cross-sectional area is defined in a portion of the collar 28b1 to bring an inside and an outside of the collar 28b1 into communication with each other. The neck 28b can be attached to the cap body 28a with the collar 28b1 joined to a flat face 28a34 of the neck seat 28a3.

Because the neck 28b is thus attached to the cap body 28a with the collar 28b1 joined to the flat face 28a34 of the neck seat 28a3, a small-opening communicating passage 60 can be formed between the flat face 28a34 and the groove 28b12. As shown in FIG. 8, the groove 28b12 can be formed with a groove bottom 28b13 and a machined surface 28b14. The groove bottom 28b13 can be formed along a semicircular arc of a perfect circle, which measures R in diameter and is contacted by an upper face 28b13 of the collar 28b1. The surface 28b14 can extend from the groove bottom 28b13 to come into contact with the semicircular arc. The cross-sectional profile of the groove 28b12 is not limited to such a substantially U-shape, and may has another groove shape such as a V-shape.

Thus, in the illustrated embodiment, the fuel cap 28 includes the cap body 28a and the neck 28b. The neck 28b is fixed to the cap body 28a with its upper end face joined to the bottom face of the cap body 28a. The small-opening communicating passage 60 is formed between the joined faces of the cap body 28a and the neck 28b. Alternatively, the small-opening communicating passage 60 may be provided between joined faces of the neck 28b and the neck seat 28a3 of the cap body 28a, in which a groove is defined in the neck seat 28a3. Because the small-opening communicating passage 60 can thus be formed only by defining a groove having e.g. a substantially U-shaped cross section in at least one of joined faces of the cap body 28a and the neck 28b, the small-opening communicating passage 60 having a desired shape can be manufactured easily.

Next, operations of supplying fuel to the fuel tank 27 will be described with reference to FIGS. 9 to 11. FIG. 9 is a cross-sectional view of the fuel cap 28 and the fuel inlet 27a, in which the fuel cap is removed and fuel is oversupplied so as to overflow from the upper end 27a5 of the fuel inlet 27a. FIG. 10 is a cross-sectional view of the same in a state in which the fuel cap 28 is being installed. FIG. 11 is a cross-sectional view of the same in a state in which the fuel cap 28 has been installed.

As shown in FIG. 9, fuel is supplied to the tank body 27A through the fuel inlet 27a with the fuel cap 28 removed. During fueling, fuel is sometimes oversupplied so as to overflow from the upper end 27a5 of the fuel inlet 27a due to a careless operation of an operator or a like.

When, as shown in FIG. 10, the fuel cap 28 is installed onto the fuel inlet 27a to seal the fuel inlet 27a in such a state in which the fuel is oversupplied, the neck 28b of the fuel cap 28 is dipped in the fuel. As a result, the liquid level of the fuel is raised, which can cause a small amount of fuel to overflow over the upper end 27a5 of the fuel inlet 27a. The thus-overflowed fuel flows down onto the seal 90 provided around the fuel inlet 27a and flows rightward. Thus, when fuel overflows from the fuel inlet 27a during fueling, the thus-overflowed fuel is discharged to the right side where the suction fan 31d is provided. In other words, the fuel is discharged to the side where the heat-generating generator 32 is not provided.

As shown in FIG. 11, when the fuel cap 28 is screwed up onto the fuel inlet 27a, an annular seal 61 of the cap body 28a seals a top face of the fuel inlet 27a to prevent the overflow of fuel. A liquid level L1 in the neck 28b is lower than a liquid level L2 of fuel on the outside of the neck 28b. However, air in the neck 28b flows through the small-opening communicating passage 60 into fuel on the outside of the neck 28b, and rises through the fuel up into an upper space 99 in the fuel inlet 27a. As a result, whereas the liquid level L1 in the neck 28b is gradually raised, the liquid level L2 on the outside of the neck 28b is gradually lowered. Hence, the liquid levels L1 and L2 become equal. Accordingly, only by installing the fuel cap 28 on the fuel inlet 27a, the liquid level of the fuel in the fuel inlet 27a is lowered, thereby preventing the fuel from flowing into the canister 50 through the inlet passage 27a7i and then through the discharging passage 27a7. This eliminates the need of performing an additional special operation to prevent the fuel from flowing into the canister 50.

As described above, the hollow neck 28b to be inserted into the fuel inlet 27a when the fuel cap 28 is installed on the fuel inlet 27a can be provided on the fuel cap 28. Because the chamber 28b6 in the neck 28b has an opening in its lower end portion and the small-opening communicating passage 60 in its upper portion, when the fuel cap 28 is installed on the fuel inlet 27a, the upper portion of the chamber 28b6 in the neck 28b is brought into communication with an interior, excluding the neck 28b, of the fuel tank 27 via the small-opening communicating passage 60.

Thus, as shown in FIG. 11, when the fuel cap 28 is installed on the fuel inlet 27a, the upper portion of the chamber 28b6 of the neck 28b is brought into communication with an interior, excluding the neck 28b, of the tank body 27A of the fuel tank 27 via the small-opening communicating passage 60. According to this structure, even when the neck 28b is inserted into the fuel inlet 27a to thereby cause fuel in the fuel inlet 27a to overflow to the outside, fuel intrudes into the chamber 28b6 through the opening defined in the lower end portion of the chamber 28b6 and pushes air accumulated in the chamber 28b6 into the tank body 27A through the small-opening communicating passage 60. Because fuel in the chamber 28b6 and that on the outside of the chamber 28b6 are thus caused to have a same liquid level, an air cell is formed in the fuel inlet 27a. This air cell prevents a rise of a liquid level in the fuel tank 27 which may otherwise occur when the temperature of the fuel in the tank body 27 increases due to exhaust heat of the engine 31 and the like. In addition, because the lower end of the chamber 28b6 of the neck 28b is open downward, the fuel intruding into the chamber 28b6 is easily discharged out of the chamber 28b6 as fuel is consumed.

Meanwhile, one end of the discharging passage 27a7, which is in communication with the canister 50 that adsorbs evaporative fuel in the tank body 27 thereonto, is open as a hole defined in the upper portion of the fuel inlet 27a by a small entry passage 27a71. According to this structure, even when fuel is oversupplied, only a small amount of fuel flows into the fuel tank 27 through the opening in the discharging passage 27a7. Therefore, the canister 50 is protected from being functionally damaged. Because a portion of the discharging passage 272a7 in communication with the canister 50 that adsorbs evaporative fuel thereonto is molded within a wall of the fuel inlet 27a, manufacturing of the portion of the discharging passage 27a7 is simplified.

According to certain embodiments, the fuel tank further includes the canister for adsorbing evaporative fuel in the tank body thereonto; and the discharging passage which is in communication with the canister, in which one end of the discharging passage is a hole defined in an upper portion of the fuel inlet. Accordingly, even when fuel is oversupplied, only a small amount of fuel flows into the fuel tank through the opening in the discharging passage through the fuel inlet. Hence, the canister is protected from being functionally damaged. Furthermore, because the liquid level of fuel in the fuel inlet can be lowered only by installing the fuel cap on the fuel inlet, overflowing of the fuel into the canister is prevented. Hence, the need of performing an additional special operation to prevent the fuel spillage is eliminated.

Although these inventions have been disclosed in the context of a certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while a number of variations of the inventions have been shown and described in detail, other modifications, which are within the scope of the inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within one or more of the inventions. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combine with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.