Evaporated fuel treatment device for motorcycle

A charge pipe passage includes a second pipe passage part which is connected to a fuel tank by way of a first pipe passage part and extends toward the other side from one side in the vehicle widthwise direction, and a third pipe passage part which is communicably connected with the second pipe passage part on the other side in the vehicle widthwise direction and has a highest part arranged at a highest position of the charge pipe passage at an intermediate position thereof. A first check valve is interposed on the third pipe passage part downstream of the highest part, an atmospheric air introducing pipe passage is connected to the third pipe passage part upstream of the first check valve, and a second check valve is interposed on the atmospheric air introducing pipe passage at a position higher than the highest part.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority to Japanese Patent Application No. 2011-063115, filed on Mar. 22, 2011, the entire content of which is incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a motorcycle in which a rider's seat is supported on a vehicle body frame, a fuel tank which is arranged below the rider's seat is supported on the vehicle body frame, an engine which generates power for driving a rear wheel is arranged below the fuel tank, and a charge pipe passage which allows oil in an engine body of the engine to absorb a fuel gas evaporated in the fuel tank is provided between the fuel tank and the engine body, and more particularly to the improvement of an evaporated fuel treatment device.

BACKGROUND OF THE INVENTION

There has been known a motorcycle in which a charge pipe passage is provided between a fuel tank and an engine body for absorbing a fuel gas generated in the fuel tank by oil in the engine body, and an atmospheric air introducing pipe passage for adjusting the pressure in the fuel tank to an atmospheric pressure is connected to an intermediate portion of the charge pipe passage in JP-UM-A-49-88172.

SUMMARY OF THE INVENTION

However, with respect to a motorcycle, when a fuel gas generated in a fuel tank is introduced into an engine body side through a charge pipe passage as in the case of the motorcycle disclosed in above-mentioned JP-UM-A-49-88172, there exists a possibility that oil in an engine body flows out to a charge pipe passage side when the motorcycle falls, and there also exists a possibility that fuel in the fuel tank flows out to the charge pipe passage side and hence, there has been a demand for suppressing the flowout of oil and fuel to the charge pipe passage when the motorcycle falls as much as possible. Further, in a motorcycle where an atmospheric pressure is introduced into an intermediate portion of a charge pipe passage through an atmospheric air introducing pipe passage, a check valve is arranged in an intermediate portion of a passage through which an atmospheric pressure is introduced into the inside of a fuel tank. However, for ensuring durability, there has been a demand for avoiding the adhesion of fuel to the check valve.

The present disclosure has been made in view of such circumstances, and it is an object of the present disclosure to provide an evaporated fuel treatment device for a motorcycle which can suppress the flowout of oil and fuel toward a charge pipe passage when the motorcycle falls, and can prevent the adhesion of fuel to a check valve which is arranged on an intermediate portion of a passage through which an atmospheric pressure is introduced into the inside of a fuel tank.

To achieve the above-mentioned object, according to the first technical feature of the present disclosure, there is provided an evaporated fuel treatment device for a motorcycle in which a rider's seat is supported on a vehicle body frame, a fuel tank which is arranged below the rider's seat is supported on the vehicle body frame, an engine which generates power for driving a rear wheel is arranged below the fuel tank, and a charge pipe passage which allows oil in an engine body of the engine to absorb a fuel gas evaporated in the fuel tank is provided between the fuel tank and the engine body, wherein the charge pipe passage includes a first pipe passage part which is connected to the fuel tank, a second pipe passage part which is communicably connected with the first pipe passage part and extends toward the other side from one side in the vehicle widthwise direction, and a third pipe passage part which is communicably connected with the second pipe passage part on the other side in the vehicle widthwise direction, is connected to the engine body and has a highest part arranged at a highest position of the charge pipe passage at an intermediate position thereof, a first check valve which prevents the flow of oil from an engine body side toward a fuel tank side is interposed on the third pipe passage part downstream of the highest part, an atmospheric air introducing pipe passage through which atmospheric air is introduced into the inside of the fuel tank is connected to a branch part which is formed on the third pipe passage part upstream of the first check valve, and a second check valve which prevents the flow of fuel from the fuel tank side is interposed on the atmospheric air introducing pipe passage at a position higher than the highest part.

The present disclosure also has, in addition to the first technical feature, the second technical feature that the branch part is formed on the third pipe passage part at a position closer to the fuel tank side than the highest part.

The present disclosure also has, in addition to the second technical feature, the third technical feature that the atmospheric air introducing pipe passage opens in atmospheric air below the second check valve.

The present disclosure also has, in addition to the third technical feature, the fourth technical feature that a filter is interposed on the atmospheric air introducing pipe passage at a position closer to an atmospheric air open side than the second check valve.

The present disclosure also has, in addition to the fourth technical feature, the fifth technical feature that the filter is interposed on a portion of the atmospheric air introducing pipe passage which has a downward gradient toward the atmospheric air open side.

The present disclosure also has, in addition to any one of the first to fifth technical features, the sixth technical feature that a bulging part which bulges upwardly so as to receive a load from the rider's seat is formed on a tank cover which covers the fuel tank from above, and the second check valve is arranged below the bulging part.

The present disclosure also has, in addition to any one of the first to fifth technical features, the seventh technical feature that an opening portion which exposes a fuel filling port formed in an upper surface of the fuel tank is formed in a tank cover which covers the fuel tank from above, a bulging part which dams up fuel overflown to the outside of the opening portion at the time of supplying fuel to the fuel filling port from above is formed on the tank cover in an upwardly bulging manner, and the second check valve is arranged below the bulging part.

Here, a first tank-side pipe passage part84ain an embodiment corresponds to the first pipe passage part of the present disclosure, a second tank-side pipe passage part84bin the embodiment corresponds to the second pipe passage part of the present disclosure, and a third tank-side pipe passage part84cin the embodiment corresponds to the third pipe passage part of the present disclosure.

According to the first technical feature of the present disclosure, the second pipe passage part which constitutes a part of the charge pipe passage extends toward the other side from the one side in the vehicle widthwise direction and hence, it is possible to suppress an amount of fuel which flows out from the fuel tank toward the charge pipe passage when the motorcycle falls. Further, the first check valve which prevents the flow of oil from the engine body side toward the fuel tank side is interposed on the third pipe passage part which is communicably connected with the second pipe passage part on the other side in the vehicle widthwise direction and hence, it is possible to prevent oil from flowing toward the fuel tank side from the engine body through the charge pipe passage when the motorcycle falls. Further, the atmospheric air introducing pipe passage through which atmospheric air is introduced into the inside of the fuel tank is connected to the third pipe passage part upstream of the first check valve and hence, it is possible to adjust a pressure in the fuel tank to an atmospheric pressure thus also suppressing the inflow of fuel toward an atmospheric air introducing pipe passage side. Further, the highest part arranged at the highest position of the charge pipe passage is arranged at the intermediate position of the third pipe passage part, and the second check valve which is interposed on the atmospheric air introducing pipe passage is arranged at a position higher than the highest part and hence, it is possible to suppress the inflow of fuel toward the second check valve thus enhancing the durability of the second check valve by preventing the adhesion of fuel to the second check valve.

According to the second technical feature of the present disclosure, the atmospheric air introducing pipe passage is connected to the third pipe passage part at the position closer to the fuel tank than the highest part and hence, even when fuel flown out from the fuel tank flows into the atmospheric air introducing pipe passage between a connection part to the charge pipe passage and the second check valve when the motorcycle falls, fuel in the atmospheric air introducing pipe passage returns to a position upstream of the highest part of the charge pipe passage when the motorcycle is raised after falling and hence, the flow of fuel toward the engine body side can be prevented.

According to the third technical feature of the present disclosure, the atmospheric air introducing pipe passage opens in atmospheric air below the second check valve and hence, even when water enters the inside of the atmospheric air introducing pipe passage through an atmospheric air open end of the atmospheric air introducing pipe passage, it is possible to make water which enters the atmospheric air introducing pipe passage difficult to reach the second check valve.

According to the fourth technical feature of the present disclosure, the filter is provided to the atmospheric air introducing pipe passage at the position closer to the atmospheric air open side than the second check valve and hence, dusts hardly adhere to the second check valve.

According to the fifth technical feature of the present disclosure, the filter is interposed on the part of the atmospheric air introducing pipe passage which has the downward gradient toward the atmospheric air open side and hence, even when the filter is wetted with water, it is possible to drain water toward the atmospheric air open end side from the filter.

According to the sixth technical feature of the present disclosure, the bulging part which receives a load from the rider's seat is formed on the tank cover in an upwardly bulging manner, and the second check valve is arranged below the bulging part. Accordingly, the second check valve is arranged at a high position and hence, it is possible to make water which enters the inside of the atmospheric air introducing pipe passage more difficult to reach the second check valve.

Further, according to the seventh technical feature of the present disclosure, the bulging part which dams up fuel overflown to the outside of the opening part at the time of filling fuel to the fuel filling port formed in the upper surface of the fuel tank from above is formed on the tank cover in an upwardly projecting manner, and the second check valve is arranged below the bulging part. Accordingly, the second check valve is arranged at a high position and hence, it is possible to make water which enters the inside of the atmospheric air introducing pipe passage more difficult to reach the second check valve.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present disclosure is explained in conjunction withFIG. 1toFIG. 12. In the explanation of the embodiment made hereinafter, directions such as “frontward direction” and “rearward direction”, and “leftward direction” and “rightward direction” follow the directions as viewed from a rider who rides on a motorcycle. Further, in the explanation made hereinafter, “ . . . ” is used for omitting the repetition of the use of the same reference symbol.

Firstly, inFIG. 1toFIG. 5, a pair of left and right seat frames15,15which constitute a part of a vehicle body frame F of a scooter-type motorcycle are formed of a pipe. The pair of left and right seat frames15,15include inclined parts15a. . . which are inclined rearwardly and upwardly and horizontal parts15b. . . which extend rearwardly from upper ends of the inclined parts15a. . . respectively, and rear ends of both horizontal parts15b. . . are integrally connected to each other by a connection part16.

A front part of a power unit P is supported on the vehicle body frame F in a vertically swingable manner by way of a link mechanism17below both seat frames15. . . , and a rear wheel WR which is arranged on a rear right side of the power unit P is pivotally supported on a rear part of the power unit P. Further, the power unit P is constituted of a forced air-cooled single cylinder 4-cycle engine E which generates power for driving the rear wheel WR and a continuously variable transmission M which is arranged between the engine E and the rear wheel WR, and a rear cushion unit18is arranged between a connection part between the inclined part15aand the horizontal part15bof the left seat frame15out of the both seat frames15. . . and a rear part of the power unit P.

An engine body19of the engine E includes a crankcase20and a cylinder head22which is arranged in front of the crankcase20. The continuously variable transmission M is housed in the inside of a transmission case23which extends rearwardly from the engine body19while using a part of the crankcase20as a constitutional element thereof, and the rear wheel WR is pivotally supported on a rear part of the transmission case23.

A fan (not shown in the drawing) which is rotated in response to an operation of the engine E is housed in the transmission case23. One end portion of an intake duct24having a bellows shape is connected to a front part of the transmission case23for introducing cooling air into the inside of the transmission case23using the fan, and the other end portion of the intake duct24is connected to a lower part of the inclined part15aof the left seat frame15. That is, air from the inside of the left seat frame15is introduced into the inside of the transmission case23as cooling air.

Most of the engine body19is covered with a shroud25, and the fan (not shown in the drawing) which sucks cooling air into the inside of the shroud25from an intake port26formed in a right side wall of the shroud25is housed in the shroud25in a state where the fan is driven by the engine E.

An intake device28is connected to an upper side surface of the cylinder head22of the engine body19. The intake device28includes an air cleaner29which is arranged on a left side of the rear wheel WR, a connecting tube30which has an upstream end thereof connected to the air cleaner29, a throttle body31which is connected to a downstream end of the connecting tube30, and an intake pipe32which connects the throttle body31and the cylinder head22. A fuel injection valve33is mounted on the intake pipe32.

Further, an exhaust device34is connected to a lower side surface of the cylinder head22, and the exhaust device34includes an exhaust muffler35which is arranged on a right side of the rear wheel WR, and an exhaust pipe36which connects the exhaust muffler35and the cylinder head22to each other.

A first cross member37is provided between intermediate portions of the inclined parts15a. . . of the both seat frames15. . . which constitute a part of the vehicle body frame F in a state where the first cross member37straddles a front part of the engine body19, and a second cross member38is provided between connection parts between the inclined parts15a. . . and the horizontal parts15b. . . of the both seat frames15. . . .

As shown inFIG. 6, the vehicle body frame F is covered with a vehicle body cover39made of a synthetic resin, and a tandem-type rider's seat40is arranged above a rear part of the vehicle body cover39.

A fuel tank42which is arranged below the rider's seat40is supported on a rear part of the vehicle body frame F in a state where the fuel tank42is arranged between the second cross member38which is provided between the both seat frames15. . . and the connection part16which integrally connects the rear parts of the both seat frames15. . . to each other. The fuel tank42is arranged above the power unit P.

To explain the embodiment also in conjunction withFIG. 7toFIG. 9, the fuel tank42is covered with a tank cover44from above, and the tank cover44is integrally connected to a rear upper edge of a synthetic-resin-made storage box43which is arranged in front of the fuel tank42between the both seat frames15. . . . The tank cover44extends rearwardly from the storage box43in a state where the tank cover44passes through a space formed between the rider's seat40and the fuel tank42. Further, the storage box43is formed with an opened upper end, and this upper-end opening portion of the storage box43is closed by a front part of the rider's seat40.

To focus onFIG. 9, the fuel tank42is formed by joining an upper tank half body45which has a box shape and opens downwardly and a lower tank half body46which has a box shape and opens upwardly to each other, and a flange part42awhich projects outwardly is formed on a joint portion of the upper tank half body45and the lower tank half body46.

A first stay47is fixedly mounted on a center portion of the second cross member38in the vehicle widthwise direction in an upwardly projecting manner, and a front portion of the flange part42aof the fuel tank42is fastened to and is supported on the first stay47. Further, second stays48. . . which project upwardly are fixedly mounted on rear portions of the horizontal parts15b. . . of the both seat frames15. . . respectively, and both left and right rear portions of the flange part42aof the fuel tank42are fastened to and are supported on the second stays48. . . .

A third stay49which projects downwardly is fixedly mounted on the second cross member38at a portion where the first stay47is fixedly mounted, a fourth stay50which projects vertically is fixedly mounted on the connection part16which integrally connects the rear parts of the both seat frames15. . . to each other, and a fender51which is arranged between the fuel tank42and the rear wheel WR so as to cover the rear wheel WR from above is supported on a lower part of the third stay49and a lower part of the fourth stay50.

A rear cover52which constitutes a part of the vehicle body cover39and is contiguously arranged with a rear part of the tank cover44and a carrier53which is arranged behind the rider's seat40are supported on an upper portion of the fourth stay50by fastening the rear cover52and the carrier53together by threadedly engaging bolts55with nuts54fixedly mounted on the upper portion of the fourth stay50.

Here, projecting parts44a. . . which project more outwardly than the rider's seat40are integrally formed with both sides of the tank cover44, and both side portions of the carrier53are formed such that the side portions of the carrier53are smoothly and contiguously arranged with the projecting parts44a. . . . Both projecting parts44a. . . and both side portions of the carrier53function as a grab rail which a pillion who is seated on a rear part of the rider's seat40can grasp.

To explain the embodiment also in conjunction withFIG. 10, the rear part of the tank cover44which covers the fuel tank42from above is supported on a fifth stay56which is formed into an approximately downwardly-opened U shape so as to straddle the rear part of the fuel tank42. Fastening plate portions56a. . . which sandwich both left and right rear portions of the flange part42aof the fuel tank42between the second stays48. . . and the fastening plate portions56a. . . respectively are mounted on both left and right end portions of the fifth stay56. Bolts57penetrate the fastening plate portions56a. . . and the flange part42aand are threadedly engaged with welded nuts58which are fixedly mounted on lower surfaces of the second stays48. . . and hence, the fastening plate portions56a. . . of both left and right end portions of the fifth stay56and the both left and right rear portions of the flange part42aof the fuel tank42are fastened together to the second stays48. . . respectively. Further, both sides of the rear part of the tank cover44are fastened to the fifth stay56by bolts59,59.

Box receiving members60,60are mounted on both sides of the first cross member37, and both sides of a front part of the storage box43are fastened to both box receiving members60. . . by bolts61,61in a state where a resilient member (not shown in the drawing) is interposed between both sides of the front part of the storage box43and the box receiving members60. . . .

Here, the rider's seat40is rotatably and pivotally supported on an upper portion of a front end of the storage box43in a state where the rider's seat40is rotatable between a closed state where the rider's seat40covers the storage box43and the tank cover44from above and an open state where the storage box43and the tank cover44are exposed. A seal member62(seeFIG. 9) which is resiliently brought into contact with an upper end of the storage box43in the closed state is mounted on a lower surface of the rider's seat40.

Further, an engaging member63is mounted on a lower part of the rider's seat40at a position corresponding to a front part of the tank cover44, and a seat locking opening part64into which the engaging member63is inserted in a state where the rider's seat40is closed is mounted on a connection part where the storage box43and the tank cover44are connected to each other.

Further, a seat locking stay65which is brought into contact with the front part of the tank cover44from below is arranged at a position corresponding to the seat locking opening portion64such that the front portion of the flange part42aof the fuel tank42is sandwiched between the seat locking stay65and the first stay47and hence, the front portion of the flange part42aand the seat locking stay65are fastened together to the first stay47by a pair of bolts66,66. Further, the front part of the tank cover44is fastened to the seat locking stay65by bolts66,66which are arranged on both left and right sides of the seat locking opening portion64.

A seat locking mechanism not shown in the drawing is provided to the seat locking stay65, and the seat locking mechanism can change over a locked state where the seat locking mechanism is engaged with the engaging member63which is inserted into the seat locking opening portion64in a state where the rider's seat40is closed thus holding the closed state of the rider's seat40and an unlocked state which allows a manipulation to open the rider's seat40by releasing the engagement between the seat locking mechanism and the engaging member63.

A fuel filling port67is formed in an upper surface of the rear part of the fuel tank42on one side in the vehicle widthwise direction, that is, a left side in the vehicle widthwise direction in this embodiment. The fuel filling port67is formed of a fuel filling sleeve68which is fixedly mounted on the upper tank half body45of the fuel tank42in an upwardly projecting manner from the upper surface of the fuel tank42, and the fuel filling port67is closed by a cap69in an openable/closeable manner. Further, a tray70which receives fuel spilt from the fuel filling port67is arranged around the fuel filling port67, and the tray70is fixed to the fuel filling sleeve68.

An upper end portion of a pump module72for discharging fuel in the fuel tank42is fastened to a center portion of the upper surface of the front part of the fuel tank42in the vehicle widthwise direction by a plurality of bolts73,73. . . . A fuel supply tube74which is communicably connected to the pump module72has a portion which extends frontwardly from the pump module72above the fuel tank42on a right side in the vehicle widthwise direction, a portion which extends along the second cross member38from the right side to a left side in the vehicle widthwise direction, and a portion which extends toward the fuel injection valve33from the second cross member38on the left side in the vehicle widthwise direction partially along the inclined part15aof the left seat frame15, and the fuel supply tube74having such portions is connected to the fuel injection valve33. To support the fuel supply tube74, a fuel supply tube support member75is mounted on the second cross member38, fuel supply tube support members76,77are mounted on the inclined part15aof the left seat frame15, and a fuel supply tube support member78is mounted on an upper surface of the shroud25in the vicinity of the fuel injection valve33.

An opening portion79which allows the fuel filling port67formed in the upper surface of the fuel tank42to face upwardly is formed in the tank cover44, and the tray70is resiliently brought into contact with a lower surface of the tank cover44so as to close the opening portion79.

A bulging part80which dams up the fuel overflown to the outside of the opening portion79at the time of supplying fuel to the fuel filling port67from above is formed on the tank cover44in an upwardly bulging manner in a state where the bulging part80is endlessly continued so as to surround the opening portion79. Particularly, a rear portion80aof the bulging part80largely bulges more upwardly than a front portion of the bulging part80, and both left and right side portions80b,80bare formed such that an upwardly bulging amount is gradually increased as the both left and right side portions80b,80bextend from a front side to a rear side. Further, a pair of projections40a. . . which are formed on a rear lower part of the rider's seat40are brought into contact with an upper portion of the rear part80aof the bulging part80when an occupant is seated on the rider's seat40so that the rear part80aof the bulging part80receives a weight of the rider's seat40.

The upper surface of the above-mentioned fuel tank42includes a higher part81where the fuel filling port67is formed and a lower part82which is lower than the higher part81, and the pump module72is arranged on the lower part82. The lower part82is arranged on a front part of the upper surface of the fuel tank42in an offset manner toward the right side in the vehicle widthwise direction, and is formed in a downwardly inclined manner toward the crankcase20of the engine body19.

A fuel gas evaporated in the fuel tank42is absorbed in oil in the crankcase20which constitutes a fuel absorption means, wherein the crankcase20is arranged below the upper surface of the fuel tank42such that the fuel gas is absorbed outside the fuel tank42. The fuel gas generated in the fuel tank42is introduced into the crankcase20through a charge pipe passage84.

The charge pipe passage84includes a first tank-side pipe passage part84awhich is connected to the upper surface of the fuel tank42, and a second tank-side pipe passage part84bwhich is communicably connected with the first tank-side pipe passage part84aand extends toward the other side of the fuel tank42from one side of the fuel tank42in the vehicle widthwise direction on an end portion thereof on a fuel tank42side. The first tank-side pipe passage part84aextends toward the one side of the fuel tank42in the vehicle widthwise direction from a connection part85connected to the upper surface of the fuel tank42, and is communicably connected to the second tank-side pipe passage part84b. In this embodiment, the connection part85connected to the upper surface of the fuel tank42is arranged behind the fuel filling port67and on a center portion of the higher part81of the upper surface of the fuel tank42in the vehicle widthwise direction in an offset manner from the fuel filling port67formed in the upper surface of the fuel tank42on the left side in the vehicle widthwise direction. The first tank-side pipe passage part84ais arranged such that the first tank-side pipe passage part84aextends leftwardly in the vehicle widthwise direction from the connection part85, and the second tank-side pipe passage part84bwhich is connected to the first tank-side pipe passage part84ais arranged such that the second tank-side pipe passage part84bextends toward the right side from the left side in the vehicle widthwise direction.

The first tank-side pipe passage part84aand the second tank-side pipe passage part84bare connected to each other such that the first tank-side pipe passage part84aand the second tank-side pipe passage part84bsurround the periphery of the fuel filling port67, a part of the first tank-side pipe passage part84aand a part of the second tank-side pipe passage part84bare arranged so as to pass below the tray70which receives fuel spilled from the fuel filling port67. The part which constitutes portion of the first tank-side pipe passage part84aand a portion of the second tank-side pipe passage part84band passes below the tray70is formed of a metallic pipe86which is bent so as to surround a part of the fuel filling sleeve68. For example, two portions of the metallic pipe86are held by pipe holding members87,87. Mounting members88,88are welded to the higher part81of the upper surface of the fuel tank42corresponding to the pipe holding members87. . . , and the pipe holding members87. . . are mounted on the mounting members88. . . by bolts89. . . and nuts90. . . . Painting treatment is applied to the fuel tank42including the mounting members88. . . , and the metallic pipe86is fastened to the fuel tank42to which the painting treatment is applied.

Further, the charge pipe passage84includes a third tank-side pipe passage part84cwhich is connected to the second tank-side pipe passage part84bon the other side in the vehicle widthwise direction (right side in this embodiment), and has a highest part91arranged at a highest position of the charge pipe passage84at an intermediate position thereof. The third tank-side pipe passage part84cis arranged to extend frontwardly above the lower part82of the upper surface of the fuel tank42.

A part of the third tank-side pipe passage part84cwhich includes at least the highest part91is formed of an elastic tube92, and the highest part91of the elastic tube92is supported on a highest part support part93mounted on the fuel tank42from below.

To focus onFIG. 11, the highest part support part93is constituted of a support plate94which is fixedly mounted on the upper surface of the fuel tank42and an upper open clamper95which is fixedly mounted on the support plate94, and the highest part91of the elastic tube92is supported on an approximately U-shaped holding part95awhich is formed on a part of the upper open clamper95formed of a round rod and opens upwardly from below.

The highest part support part93is arranged below the right side part80bof the bulging part80which is formed on the tank cover44so that a relatively large empty space is formed above the highest part support part93. In view of the above, a rib44bwhich prevents the elastic tube92from being upwardly removed from the upper open clamper95is integrally formed on the tank cover44such that the rib44btraverses the inside of the right side part80b. It is desirable that the rib44bis arranged just above the upper open clamper95. Although the rib44bis arranged just above the upper open clamper95in this embodiment, the rib44bmay be arranged in a slightly offset manner in the longitudinal direction of the elastic tube92from just above the upper open clamper95provided that the upward removal of the elastic tube92from the upper open clamper95can be prevented at such a position.

Further, as clearly shown inFIG. 10, a part of the charge pipe passage84ranging from the highest part91to the connection part85with the fuel tank42is arranged with a downward gradient toward the connection part85.

A first check valve96which prevents a backflow of a fuel gas toward a fuel tank42side is interposed on a part of the third tank-side pipe passage part84cof the charge pipe passage84downstream of the highest part91in a state where the first check valve96is supported on the fuel tank42. The first check valve96is arranged above the lower part82of the upper surface of the fuel tank42.

A part of the third tank-side pipe passage part84cof the charge pipe passage84includes the elastic tube92which has a downstream end thereof connected to the first check valve96and is arranged above the fuel tank42, and an elastic tube97which has an upstream end thereof connected to the first check valve96and is arranged above the fuel tank42. The elastic tube92is held by an upper open clamper98downstream of a portion thereof held by the upper open clamper95, and an upstream end portion of the elastic tube97is held by an upper open clamper99.

The upper open clampers98,99are fixedly mounted in common on a support plate100which is fixedly mounted on the upper surface of the fuel tank42. The removal of the elastic tubes92,97from the upper open clampers95,98,99mounted on the upper surface of the fuel tank42is prevented by the tank cover44which covers the fuel tank42from above.

A branch part101is formed on the third tank-side pipe passage part84cof the charge pipe passage84at a position closer to the fuel tank42side than the first check valve96. An atmospheric air introducing pipe passage102which introduces atmospheric air to the inside of the fuel tank42is connected to the branch part101, and a second check valve103which prevents the flow of fuel from the fuel tank42side is interposed on the atmospheric air introducing pipe passage102. Further, as clearly shown inFIG. 10, the second check valve103is arranged at a position higher than the highest part91of the charge pipe passage84.

The atmospheric air introducing pipe passage102opens in atmospheric air below the second check valve103. In this embodiment, the atmospheric air introducing pipe passage102is connected to the connection part16in such a manner that the atmospheric air introducing pipe passage102opens in atmospheric air in the pipe-shaped connection part16which connects the rear parts of the pair of left and right seat frames15. . . to each other.

Further, a filter104is interposed on the atmospheric air introducing pipe passage102at a position closer to an atmospheric air open side, that is, a connection part16side than the second check valve103. The filter104is interposed on a portion of the atmospheric air introducing pipe passage102which has a downward gradient toward the atmospheric air open side, that is, the connection part16side.

The atmospheric air introducing pipe passage102includes an elastic tube105which has one end portion thereof connected to the branch part101and the other end portion thereof connected to the second check valve103, an elastic tube106which has one end portion thereof connected to the second check valve103and the other end thereof connected to the filter104, and an elastic tube107which has one end portion thereof connected to the filter104and the other end portion thereof connected to the connection part16of the vehicle body frame F. The elastic tube106is arranged in an arcuately bent shape while connecting the second check valve103and the filter104arranged at an oblique rearward and downward position from the second check valve103, and a part of the elastic tube106and the elastic tube107are arranged such that these parts have a downward gradient toward the connection part16while connecting the filter104therebetween.

The other end portion of the elastic tube105and the one end portion of the elastic tube106are held by upper open clampers108,109at a position where the second check valve103is sandwiched between the elastic tube105and the elastic tube106. These upper open clampers108,109are fixedly mounted on the fifth stay56which constitutes a part of the vehicle body frame F so that the removal of the elastic tubes105,106from these upper open clampers108,109can be prevented by the tank cover44which covers the fuel tank42from above.

The second check valve104is arranged below the rear part80awhich receives a load from the rider's seat40out of the bulging part80formed on the tank cover44which covers the fuel tank42from above.

The charge pipe passage84includes: a communication pipe passage part84dwhich is connected to the third tank-side pipe passage part84con the other side in the vehicle widthwise direction (a right side in this embodiment) and extends toward the one side in the vehicle widthwise direction (a left side in this embodiment) along the second cross member38; a first engine-side pipe passage part84ewhich is connected to the communication pipe passage part84dand is arranged above the engine body19in a vertically extending manner on the one side in the vehicle widthwise direction; a second engine-side pipe passage part84fwhich is connected to a lower end of the first engine-side pipe passage part84eon the one side in the vehicle widthwise direction and extends from the one side to the other side in the vehicle widthwise direction above the engine body19; and a third engine-side pipe passage part84gwhich is connected to the second engine-side pipe passage part84fon the other side in the vehicle widthwise direction and is connected to the engine body19.

In this embodiment, the communication pipe passage part84dis connected to the third tank-side pipe passage part84con the right side in the vehicle widthwise direction and extends leftwardly in the vehicle widthwise direction along the second cross member38. The communication pipe passage part84dis connected to an upper end of the first engine-side pipe passage part84eon the left side in the vehicle widthwise direction and extends rightwardly in the vehicle widthwise direction along the second cross member38and is connected to the fuel tank42through the third, the second and the first tank-side pipe passage parts84c,84b,84a. The first engine-side pipe passage part84eextends in the vertical direction on the left side in the vehicle widthwise direction, the second engine-side pipe passage part84fis arranged in an extending manner from the left side to the right side in the vehicle widthwise direction above the engine body19, and the third engine-side pipe passage part84gis connected to the crankcase20of the engine body19on the right side in the vehicle widthwise direction.

A frame-side support part110which supports an intermediate part of the first engine-side pipe passage part84eis mounted on the vehicle body frame F, and on an upper surface of the shroud25of the engine E, an engine-side support part111which supports an intermediate part of the second engine-side pipe passage part84fis mounted. The engine-side support part111is mounted on the upper surface of the shroud25together with the fuel supply tube support member77by bolts112.

The engine-side support part111is arranged at a position closer to the one side in the vehicle widthwise direction (left side in this embodiment) than the intake device28as viewed in a plan view, and the frame-side support part110is arranged at an oblique rearward and upward position from the engine-side support part111, and is mounted on the inclined part15aof the seat frame15on the one side in the vehicle widthwise direction (left side in this embodiment) out of the both seat frames15. . . .

Further, at least a part of the charge pipe passage84between the engine-side support part111and the frame-side support part110is formed of the elastic tube97. In this embodiment, the elastic tube97which forms a part of the third tank-side pipe passage part84cand has one end portion thereof connected to the first check valve96constitutes the whole communication pipe passage part84d, the whole first engine-side pipe passage part84e, the whole second engine-side pipe passage part84fand a part of the third engine-side pipe passage part84g.

Further, as shown inFIG. 1, the second engine-side pipe passage part84fis arranged so as to pass below the connecting tube30and the throttle body31of the intake device28.

As shown inFIG. 12, the third engine-side pipe passage part84gis connected to the crankcase20in such a manner that the third engine-side pipe passage part84gis arranged adjacent to, inside in the vehicle widthwise direction, a fuel supply pipe116which is arranged on a right side part of the crankcase20for supplying oil to the inside of the crankcase20of the engine body19, extends obliquely in the upward direction, and has an upper end portion thereof closed by a cap115. The third engine-side pipe passage part84gis constituted of a part of the elastic tube97, and a metallic tubular body117which has an upper end portion thereof connected to the elastic tube97and is fixedly mounted on the crankcase20. The other end of the tubular body117opens in the inside of the crankcase20below an oil surface L of oil in the crankcase20. Accordingly, a fuel gas which is evaporated in the fuel tank42and is introduced through the charge pipe passage84is absorbed by oil in the crankcase20.

Next, the manner of operation of this embodiment is explained. The charge pipe passage84which introduces a fuel gas evaporated in the fuel tank42toward the crankcase20which constitutes the fuel absorption means includes the first tank-side pipe passage part84awhich is connected to the upper surface of the fuel tank42and the second tank-side pipe passage part84bwhich is communicably connected with the first tank-side pipe passage part84aand extends toward the other side (right side in this embodiment) of the fuel tank42from the one side (left side in this embodiment) of the fuel tank42in the vehicle widthwise direction on the end portion thereof on the fuel tank42side. The first tank-side pipe passage part84aand the second tank-side pipe passage part84bare fixed to the upper surface of the fuel tank42. Accordingly, even when the first tank-side pipe passage part84ais connected to the fuel tank42at either one of positions in the vehicle widthwise direction, it is possible to suppress an amount of fuel which flows out from the fuel tank42toward the crankcase20through the charge pipe passage84when the motorcycle falls. Further, at least the part of the charge pipe passage84can be mounted on the fuel tank42in advance and hence, the structure can contribute to the enhancement of assembling property.

The first tank-side pipe passage part84aextends toward the one side (left side in this embodiment) of the fuel tank42from the connection part85connected to the upper surface of the fuel tank42in the vehicle widthwise direction, and is connected to the second tank-side pipe passage part84b. Accordingly, the flowout of fuel when the motorcycle falls can be effectively suppressed.

The fuel filling port67is formed in the upper surface of the fuel tank42on the one side in the vehicle widthwise direction (left side in this embodiment), and the first tank-side pipe passage part84awhich is connected to the upper surface of the fuel tank42at a position offset from the fuel filling port67and the second tank-side pipe passage part84bare connected to each other in a state where the first tank-side pipe passage part84aand the second tank-side pipe passage part84bsurround the periphery of the fuel filling port67. Accordingly, the part of the first tank-side pipe passage part84aand the part of the second tank-side pipe passage part84bcan be arranged with large curvatures respectively by making use of a dead space around the fuel filling port67thus easing the arrangement of the first tank-side pipe passage part84aand the second tank-side pipe passage part84b.

The tray70which receives fuel spilt from the fuel filling port67is arranged around the fuel filling port67, and the part of the first tank-side pipe passage part84aand the part of the second tank-side pipe passage part84bare arranged to pass below the tray70. Accordingly, even when the part of the first tank-side pipe passage part84aand the part of the second tank-side pipe passage part84bare arranged so as to surround the fuel filling port67, an area of the tray70can be increased.

The charge pipe passage84includes the third tank-side pipe passage part84cwhich is connected to the second tank-side pipe passage part84bon the other side in the vehicle widthwise direction (right side in this embodiment), and has the highest part91arranged at the highest position of the charge pipe passage84at the intermediate position thereof. Accordingly, the flowout of fuel when the motorcycle falls can be more effectively suppressed.

Further, the part of the third tank-side pipe passage part84cwhich includes at least the highest part91is formed of the elastic tube92, and the highest part91of the elastic tube92is supported on the highest part support part93mounted on the fuel tank42from below. Accordingly, the degree of freedom in design can be enhanced by determining the height of the highest part91based on the height of the highest part support part93. Further, the part of the charge pipe passage84ranging from the highest part91to the connection part85with the fuel tank42is arranged with a downward gradient toward the connection part85side. Accordingly, fuel stored in the charge pipe passage84between the highest part91and the fuel tank42can be easily returned to the fuel tank42side.

The downstream end of the charge pipe passage84is connected to the crankcase20in a state where the downstream end of the charge pipe passage84opens in the oil in the crankcase20, and the first check valve96which prevents a backflow of a fuel gas toward the fuel tank42is interposed on a portion of the charge pipe passage84downstream of the highest part91. Accordingly, it is possible to effectively prevent oil in the crankcase20from flowing toward the fuel tank42by the first check valve96, and it is also possible to enhance assembling property by supporting the first check valve96on the fuel tank42.

The upper surface of the fuel tank42includes the higher part81in which the fuel filling port67is formed and the lower part82lower than the higher part81, and the first check valve96is arranged on the lower part82. Accordingly, it is possible to prevent the first check valve96from taking a high arrangement position. Further, the lower part82is formed in a downwardly inclined manner toward the crankcase20. Accordingly, it is possible to make the flow of a fuel gas which passes through the first check valve96smooth.

The atmospheric air introducing pipe102which introduces an atmospheric air to the inside of the fuel tank42is connected to the branch part101which is formed on the third tank-side pipe passage part84cof the charge pipe passage84at a position closer to the fuel tank42side than the first check valve96, and the second check valve103which prevents the flow of fuel from the fuel tank42side is interposed on the atmospheric air introducing pipe102. Accordingly, when the pressure inside the fuel tank42becomes a negative pressure, atmospheric air is introduced into the inside of the fuel tank42so as to adjust the pressure in the fuel tank42to an atmospheric pressure. Further, it is possible to prevent a fuel gas from being discharged to the outside through the atmospheric air introducing pipe102by the second check valve103.

The parts of the elastic tubes92,97which constitute at least a part of the charge pipe passage84and are arranged above the fuel tank42are held by the upper open clampers95,98,99which are mounted on the upper surface of the fuel tank42, and the fuel tank42is covered with the tank cover44which prevents the removal of the elastic tubes92,97from the upper open clampers95,98,99. Accordingly, the part of the charge pipe passage84can be supported on the fuel tank42with the simple structure and hence, the assembling property can be enhanced.

Paint treatment is applied to the outer surface of the fuel tank42, and the metallic pipe86which constitutes the part of the charge pipe passage84is fastened to the fuel tank42. Accordingly, compared to a case where the metallic pipe86is fixed to the fuel tank42by welding, it is unnecessary to apply masking to the metallic pipe86and hence, a painting cost can be reduced.

The second check valve103is arranged at a position higher than the highest part91formed on the third tank-side pipe passage part84cof the charge pipe passage84and hence, the second check valve103suppresses the inflow of fuel toward the second check valve103thus enhancing durability of the second check valve103by preventing the adhesion of fuel to the second check valve103.

The branch part101is arranged on the third tank-side pipe passage part84cat the position closer to the fuel tank42side than the highest part91. Accordingly, even when fuel flown out from the fuel tank42flows into the atmospheric air introducing pipe passage102at the connection part with the charge pipe passage84, that is, between the branch part101and the second check valve103when the motorcycle falls, fuel in the atmospheric air introducing pipe passage102returns to the position upstream of the highest part91of the charge pipe passage84when the motorcycle is raised after falling and hence, the flow of fuel toward the engine body19can be prevented.

The atmospheric air introducing pipe passage102opens in atmospheric air below the second check valve103. Accordingly, even when water enters the inside of the atmospheric air introducing pipe passage102through the atmospheric air open end of the atmospheric air introducing pipe passage102, it is possible to make water which enters the atmospheric air introducing pipe passage102difficult to reach the second check valve103. The filter104is interposed on the atmospheric air introducing pipe passage102at the position closer to the atmospheric air open side than the second check valve103and hence, dusts hardly adhere to the second check valve103. Further, the filter104is interposed on the part of the atmospheric air introducing pipe passage102which has a downward gradient toward the atmospheric air open side and hence, even when the filter104is wetted with water, it is possible to drain water toward the atmospheric air open end side from the filter104.

On the tank cover44which covers the fuel tank42from above and includes the opening portion79which allows the fuel filling port67formed in the upper surface of the fuel tank42to face upwardly, the bulging part80which receives a load from the rider's seat40and dams up fuel overflown to the outside of the opening portion79at the time of filling fuel to the fuel filling port67from above is formed in an upwardly bulging manner, and the second check valve103is arranged below the bulging part80. Accordingly, the second check valve103is arranged at a high position and hence, it is possible to make water which enters the inside of the atmospheric air introducing pipe passage102more difficult to reach the second check valve103.

The charge pipe passage84includes: the first engine-side pipe passage part84ewhich is arranged above the engine body19in a vertically extending manner on the one side in the vehicle widthwise direction (left side in this embodiment) of the engine body19; the second engine-side pipe passage part84fwhich is connected to the lower end of the first engine-side pipe passage part84eon the one side in the vehicle widthwise direction and extends from the one side to the other side in the vehicle widthwise direction (right side in this embodiment) above the engine body19; and the third engine-side pipe passage part84gwhich is connected to the second engine-side pipe passage part84fon the other side in the vehicle widthwise direction and is connected to the engine body19. Accordingly, it is possible to suppress the flow out of oil in the engine body19to the inside of the charge pipe passage84when the motorcycle falls.

Further, the frame-side support part110which supports the first engine-side pipe passage part84eis mounted on the vehicle body frame F, the engine-side support part111which supports the second engine-side pipe passage part84fis mounted on the shroud25of the engine E, and at least the part of the charge pipe passage84between the engine-side support part111and the frame-side support part110is formed of the elastic tube97and hence, the charge pipe passage84can follow the swing of the engine E.

The second engine-side pipe passage part84fis arranged so as to pass below the intake device28which extends rearwardly from the upper side surface of the cylinder head22of the engine body19and hence, a part of the charge pipe passage84can be arranged by making use of a dead space below the intake device28.

The engine-side support part111is mounted on the engine E at the position closer to the one side in the vehicle widthwise direction than the intake device28as viewed in a plan view. Accordingly, a part of the charge pipe passage84which passes below the intake device, that is, the second engine-side pipe passage part84fcan be fixed such that the second engine-side pipe passage part84fdoes not swing relative to the engine body19and hence, the intake device28can be arranged close to the engine body19while obviating the contact of the intake device28with the charge pipe passage84thus contributing to making the engine E compact.

The vehicle body frame F includes the pair of left and right seat frames15. . . which has the inclined parts15a. . . extending rearwardly and upwardly respectively, the power unit P is swingably supported on the vehicle body frame F below the seat frames15. . . , and the frame-side support part110is arranged at an oblique rearward and upward position from the engine-side support part111and is mounted on the inclined part15aof the seat frame15on the one side in the vehicle widthwise direction (left side in this embodiment) out of the both seat frames15. . . . Accordingly, the engine-side support part111and the frame-side support part110can be arranged in a spaced-apart manner from each other in the longitudinal direction and hence, a diffraction amount of the elastic tube97caused by the swing of the power unit P can be made small.

Further, the second cross member38is provided between the pair of seat frames15. . . behind the frame-side support part110, the fuel tank42which is arranged behind the second cross member38is supported on the both seat frames15. . . , and the charge pipe passage84includes the communication pipe passage part84dwhich is communicably connected to the upper end of the first engine-side pipe passage part84eon the one side in the vehicle widthwise direction, extends toward the other side in the vehicle widthwise direction along the second cross member38, and is connected to the fuel tank42. Accordingly, the flowout of oil into the inside of the charge pipe passage84from the engine body19side can be more effectively suppressed.

Although the embodiment of the present disclosure has been explained heretofore, the present disclosure is not limited to the above-mentioned embodiment, and various design modifications may be made without departing from the gist of the present disclosure described in Claims.

Although a specific form of embodiment of the instant invention has been described above and illustrated in the accompanying drawings in order to be more clearly understood, the above description is made by way of example and not as a limitation to the scope of the instant invention. It is contemplated that various modifications apparent to one of ordinary skill in the art could be made without departing from the scope of the invention which is to be determined by the following claims.