Evaporated fuel control device for saddle-type vehicles

There is provided an evaporated fuel control device for a saddle-type vehicle in which an air supply passage is laid out without being disposed at a higher position than a fuel tank. The fuel tank 12 is disposed at a higher position than the engine 20, an evaporated fuel passage 110 is routed as a descending passage from the fuel tank 12 to the engine 20, and an air supply passage 120 is jointed to a halfway position of the evaporated fuel passage 110 which is located at a fuel tank 12 side with respect to a first check valve 117 and positionally lower than the uppermost portion of the fuel tank 12.

TECHNICAL FIELD

The present invention relates to an evaporated fuel control device for saddle-type vehicles.

BACKGROUND ART

A two-wheeled motor vehicle that is provided with a canister for temporarily adsorbing evaporated fuel in a fuel tank and supplies the fuel to an engine intake system from the canister is disclosed (see Patent Document 1, for example). When a canister is disposed in a saddle-type vehicle such a two-wheeled motor vehicle or the like, the design of the vehicle body is restricted and also the vehicle body grows in size in order to secure the configuration space of the canister.

A method of introducing evaporated fuel in a fuel tank to a crank chamber after the evaporated fuel is made to pass through oil in an oil pan of the crank chamber and then supplying the evaporated fuel to an engine intake system together with blow-by gas when an engine is driven is disclosed as a method using no canister (see Patent Document 2, for example).

PRIOR ART DOCUMENTS

Patent Document

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, it is required in the construction of the cited document 2 to provide an evaporated fuel passage for making evaporated air flow therethrough and an air supply passage for supplying outdoor air into a fuel tank. Therefore, when the method of the cited document 2 is applied to a saddle-type vehicle, various problems occur in adaptation of this method to the existing part arrangement and usability of the saddle-type vehicle.

For example, there is considered a layout in which the air supply passage is opened to the atmosphere at the upper side of the fuel tank. However, with respect to a saddle-type vehicle in which a fuel tank is disposed above an engine, a seat is disposed above the fuel tank or the fuel tank itself is disposed at the uppermost portion of the vehicle, so that it is difficult to secure a layout space above the tank. Therefore, when the space is set above the tank, it would cause such a problem that the seat is located at a high position. Since the layout space itself is originally small in the saddle-type vehicle, it has been desired to design the evaporated fuel passage and the air supply passage in compact size.

The present invention has been implemented in view of the foregoing situation, and has an object to provide an evaporated fuel control device for a saddle-type vehicle that enables an air supply passage to be laid out in the saddle-type vehicle without being disposed at a higher position than a fuel tank.

Means of Solving the Problem

In order to attain the above object, an evaporated fuel control device for a saddle-type vehicle having an engine, a fuel tank for stocking fuel, an evaporated fuel passage that is connected to the fuel tank at one end thereof and connected to oil in the engine at the other end thereof, a first check valve that is provided at a halfway position of the evaporated fuel passage and stops flow from the engine to the fuel tank, an air supply passage for supplying outdoor air into the fuel tank, and a second check valve that is provided at some halfway position of the air supply passage and stops flow from the fuel tank to the atmosphere, is characterized in that the fuel tank is disposed at an upper side of the engine, the evaporated fuel passage is routed as a descending path from the fuel tank to the engine, the air supply passage is joined to a halfway position of the evaporated fuel passage that is located at a fuel tank side with respect to the first check valve and positionally lower than the uppermost portion of the fuel tank.

According to this construction, the fuel tank is disposed at a higher position than the engine, the evaporated fuel passage is routed as a descending passage from the fuel tank to the engine, and the air supply passage120is jointed to a halfway position of the evaporated fuel passage which is located at the fuel tank side with respect to the first check valve and positionally lower than the uppermost portion of the fuel tank. Therefore, the air supply passage can be laid out in the saddle-type vehicle without being disposed at a higher position than the fuel tank.

In the above construction, the saddle-type vehicle may have a head pipe for supporting a front wheel so that the front wheel is steerable, and a main frame extending rearwards and downwards from the head pipe, the engine may be disposed at a lower side of the main frame, the fuel tank may be disposed at an upper side of a rear frame extending rearwards and upwards from a rear portion of the main frame, and the evaporated fuel passage may protrude rearwards from the fuel tank and may be further disposed along the rear frame and connected to the engine. According to this construction, the evaporated fuel passage may be routed by using the rear frame.

In the above construction, a pair of right and left rear frames may be provided, the evaporated fuel passage may be disposed along one rear frame of the pair of right and left rear frames, and a fuel supply passage for supplying fuel from the fuel tank to an intake system of the engine may be disposed along the other rear frame. According to this construction, the fuel supply passage and the evaporated fuel passage may be allocated to and disposed at the right and left sides, so that they can be easily assembled.

Furthermore, in the above construction, the rear frame may be provided with a tank support bracket that extends upwards from the rear frame and supports the fuel tank, the air supply passage may extend upwards along the tank support bracket, and a part of the air supply passage may be supported by the tank support bracket or the fuel tank. According to this construction, the air supply passage can be supported by using an existing part, and increase of the number of parts can be avoided.

In the above construction, the second check valve may be disposed between the tank support bracket and the fuel tank, and a portion of the air supply passage that is located at an open end side thereof with respect to the second check valve may be supported by the fuel tank. According to this construction, the second check valve can be disposed by using the dead space between the tank support bracket and the fuel tank, and the open end of the air supply passage can be surely positioned by the fuel tank.

Still furthermore, in the above construction, the fuel tank may be disposed at a substantially middle position between the front wheel and a rear wheel in a vehicle travel direction. According to this construction, the fuel tank and the open end of the air supply passage can be disposed at positions which are far away from the front and rear wheels at which dust is easily raised, and also relatively distant from the ground surface.

In the above construction, the saddle-type vehicle may be equipped with a seat on which a driver sits, and the seat may be disposed so as to cover an upper surface of the fuel tank. According to this construction, in the evaporated fuel control device, the air supply passage can be laid out without being disposed at a higher position than the fuel tank. Therefore, even in the arrangement that the seat covers the upper surface of the fuel tank, the seat can be set at a low position as in the case of a vehicle having no evaporated fuel control device.

Furthermore, in the above construction, the first check valve may be disposed to be positionally overlapped with the engine in top view. According to this construction, when oil from the engine exists in the first check valve, the fluidity of the oil is increased by heat ascending from the engine to enable the oil from easily return to the engine side. When liquid fuel exists in the first check valve, the liquid fuel can be positively evaporated by the heat of the engine.

Effect of the Invention

According to the present invention, the fuel tank is disposed at a higher position than the engine, the evaporated fuel passage is routed as a descending passage from the fuel tank to the engine, and the air supply passage120is jointed to a halfway position of the evaporated fuel passage which is located at the fuel tank side with respect to the first check valve and positionally lower than the uppermost portion of the fuel tank. Therefore, the air supply passage can be laid out in the saddle-type vehicle without being disposed at a higher position than the fuel tank.

Furthermore, the saddle-type vehicle has a head pipe for supporting a front wheel so that the front wheel is steerable, and a main frame extending rearwards and downwards from the head pipe, the engine is disposed at a lower side of the main frame, the fuel tank is disposed at an upper side of a rear frame extending rearwards and upwards from a rear portion of the main frame, and the evaporated fuel passage protrudes rearwards from the fuel tank and may be further disposed along the rear frame and connected to the engine, whereby the evaporated fuel passage can be routed by using the rear frame.

Furthermore, a pair of right and left rear frames is provided, the evaporated fuel passage is disposed along one rear frame of the pair of right and left rear frames, and a fuel supply passage for supplying fuel form the fuel tank to an intake system of the engine is disposed along the other rear frame, whereby the fuel supply passage and the evaporated fuel passage can be allocated to and disposed at the right and left sides, so that they can be easily assembled.

Furthermore, the rear frame is provided with a tank support bracket that extends upwards from the rear frame and supports the fuel tank, the air supply passage extends upwards along the tank support bracket, and a part of the air supply passage is supported by the tank support bracket or the fuel tank, whereby the air supply passage can be supported by using an existing part, and increase of the number of parts can be avoided.

The second check valve is disposed between the tank support bracket and the fuel tank, and a portion of the air supply passage that is located at an open end side thereof with respect to the second check valve is supported by the fuel tank, whereby the second check valve can be disposed by using the dead space between the tank support bracket and the fuel tank, and the open end of the air supply passage can be surely positioned by the fuel tank.

Furthermore, the fuel tank is disposed at a substantially middle position between the front wheel and a rear wheel in a vehicle travel direction, whereby the fuel tank and the open end of the air supply passage can be disposed at positions which are far away from the front and rear wheels at which dust is easily raised, and also relatively distant from the ground surface.

Furthermore, the seat on which a driver sits is disposed so as to cover an upper surface of the fuel tank, whereby the evaporated fuel control device can be laid out without disposing the air supply passage at a higher position than the fuel tank. Therefore, even in the arrangement that the seat covers the upper surface of the fuel tank, the seat can be set at a low position as in the case of a vehicle having no evaporated fuel control device.

Furthermore, the first check valve is disposed to be positionally overlapped with the engine in top view, whereby when oil from the engine exists in the first check valve, the fluidity of the oil is increased by heat ascending from the engine to enable the oil from easily return to the engine side, and when liquid fuel exists in the first check valve, the liquid fuel can be positively evaporated by the heat of the engine.

MODE FOR CARRYING OUT THE INVENTION

An embodiment according to the present invention will be hereunder described with reference to the drawings. In the following description, the front-and-rear, right-and-left and up-and-down directions are defined as directions based on ca view from a rider of the vehicle.

FIG. 1is a right side view of a two-wheeled motor vehicle in which an evaporated fuel control device according to an embodiment of the present invention is mounted, andFIG. 2is a diagram showing the internal construction of the two-wheeled motor vehicle.

As shown inFIGS. 1 and 2, the two-wheeled motor vehicle10is a saddle-type vehicle in which a fuel tank12is disposed below a seat11on which a rider (driver) sits, and it has a foot straddle portion M which is U-shaped in side view and disposed ahead of the seat11and a fuel tank12, and an engine (also called as a power unit)20as an internal combustion engine which is disposed below the foot straddle portion M and the fuel tank12.

This two-wheeled motor vehicle10has a vehicle body frame2, a steering stem which is freely turnably supported on a head pipe3of the vehicle body frame2and constitutes a part of a steering system, a pair of right and left front forks5joined to the lower portion of the steering stem4, a steering handle6joined to the upper end of the steering stem4, a front wheel7which is freely rotatably supported on the front forks5, swing arms8which is supported at the rear portion of the vehicle body frame2so as to be freely swingable in the up-and-down direction, a rear wheel9which is freely rotatably supported at the rear ends of the swing arms8, and an engine20supported at the lower portion of the intermediate position in the front-and-rear direction of the vehicle body frame2(between the front wheel7and the rear wheel9).

FIG. 3shows the vehicle body frame2together with the peripheral construction thereof.

The vehicle body frame2has a single main frame22extending rearwards and downwards from the head pipe3provided at the front end, a pair of right and left rear frames23which extend rearwards and upwards from the rear portion of the main frame22, and a pair of right and left pivot plates24which extend downwards from the rear portion of the main frame22. The main frame22and the rear frames23are formed of metal pipes.

The rear frames23have pairs of right and left first and second rear frames25and26which extend from the rear portion of the main frame22rearwards and upwards. The first rear frame25has a slope portion25A extending from the rear end of the main frame22rearwards and upwards, and a horizontal portion25B which horizontally extends rearwards from the rear end of the slope portion25A, the slope portion25A and the horizontal portion25B being provided integrally with each other, and a carrier31and a tail lamp32(seeFIG. 2) are supported by the horizontal portions25B.

The second rear frame26extends from the main frame22rearwards and upwards at the front and upper side of the first rear frame25, and the rear end thereof is joined to the slope portion25A of the first rear frame25.

As described above, the rear frame23is constructed by the first rear frame25and the second rear frame26, and thus the rigidity of the rear frame23itself can be sufficiently secured. Furthermore, since the second rear frame26bridges the main frame22and the first rear frame25, it functions as a reinforcing frame for reinforcing the joint rigidity of the main frame22and the first rear frame25, so that the rigidity of the rear frame23can be efficiently enhanced.

The pair of right and left second rear frames26are provided with a pair of right and left tank support brackets41projecting upwards, and the fuel tank12is supported at the upper side of the rear frames23through the tank support brackets41. The seat11is supported at the upper side of the fuel tank12so as to be freely openable and closable, and the seat11also serves as a lid for covering the upper side of the fuel tank12.

Here, inFIG. 2, reference numeral42represents a pair of right and left downwards extending stays extending downwards from the right and left side walls of the fuel tank12, and the lower ends of the pair of right and left downwards extending stays42are fastened to the tank support brackets41by bolts, whereby the fuel tank12is supported at the upper side of the rear frames23.

The rear frames23are provided with a pair of right and left tank rear side support brackets43for supporting the rear portion of the fuel tank12. The tank rear side support brackets43are provided at the upper portions of the slope portions25A of the first rear frames25, and a flange portion12F which is integrally provided to the fuel tank12is fastened and fixed to the tank rear side support brackets43by bolts.

Accordingly, the fuel tank12is fixed to the second rear frames26at the front right and left sides thereof, and fixed to the first rear frames25at the rear right and left sides thereof, whereby the fuel tank12is supported with sufficient support strength by both the frames25and26.

As shown inFIG. 2, the swing arms8are pivotally supported through a pivot shaft33on the right and left pivot plates24so as to be freely swingable, and a pair of right and left rear cushions34are interposed between the rear portions of the swing arms8and the horizontal portions25B of the first rear frames25.

Furthermore, a main stand35(seeFIG. 1) is secured to the pivot plates24so that the vehicle body is parked in a vertical position on the ground surface.FIG. 1shows a state that the main stand35is put down to a parking position, and the main stand35is designed like a lickstand which stands to be tilted forwards and downwards at the parking position. As shown in FIG.1, the rear wheel9is lifted up by setting the main stand35.

The upper portion of the engine20is suspended from a support bracket36which is vertically provided to the center portion of the main frame22, and the rear portion of the engine20is fixed to the upper and lower portions of the pivot plates24, whereby the engine20is supported below the main frame22and ahead of the pivot plates24.

As shown inFIGS. 1 and 2, the two-wheeled motor vehicle10has a vehicle body cover50formed of synthetic resin with which the substantially whole vehicle body is covered. The vehicle body cover50has a front cover51covering the front portion of the vehicle body (head pipe3, etc.), a main frame cover52which is connected to the front cover51from the rear side of the head pipe3so as to pinch the head pipe3and covers the main frame22partway, a rear side cover53which is connected to the rear edge of the main frame cover52and covers the periphery of the fuel tank12, and a handle cover54which covers the center portion in the right-and-left direction of the handle6.

The main frame cover52covers the main frame22from the upper side thereof over the right and left sides thereof to both the sides of a cylinder portion61of the engine20and the upper edge of a crank case62of the engine20. Furthermore, a pair of right and left leg shields55covering the front side of the rider's feet are formed integrally with the main frame cover52.

The rear side cover53is provided with freely detachable lids53A, and parts inside the rear side cover53can be accessed by detaching the lids53A.

Reference numeral56represents a front fender which is secured to the front fork5and covers the front wheel7from the upper side, and reference numeral57represents a rear fender which is secured to the rear frames23and covers the rear wheel9from the upper side.

Next, the engine20and the surrounding construction thereof will be described.

The engine20is a single cylinder type four-cycle air-cooled engine, and it is a horizontal engine in which the cylinder portion61protrudes substantially horizontally from the front portion of the crank case62to the front side thereof as shown inFIG. 2. By adopting the horizontal engine, the vehicle body can be designed so that the center of gravity thereof is low, and the foot straddle portion M can be set at a low position by positionally lowering the main frame22, so that the getting-on-and-off performance can be enhanced.

The cylinder portion61is constructed by a cylinder block61A joined to the front portion of the crank case62, a cylinder head61B joined to the front portion of the cylinder block61A and a head cover61C joined to the front portion of the cylinder head61B.

An intake pipe70, a throttle body (fuel supply device)71and an air cleaner unit72are successively pipe-connected to the upper surface of the cylinder head61B as the upper front portion of the engine20, and these parts constitute an engine intake system. This engine intake system is disposed between the engine20and the main frame22and inside the main frame cover52, that is, the engine intake system is laid out in a space above the engine20. An injector65for supplying fuel to the engine intake system is secured to the intake pipe70.

Furthermore, a single exhaust pipe75is connected to the lower surface of the cylinder head61B. The exhaust pipe75extends downwardly, bends and extends rearwards and then is connected to a muffler76disposed at the right side of the rear wheel9. That is, an engine exhaust system is constructed by the exhaust pipe75and the muffler76, and the engine exhaust system is laid out in a space below the engine20and at a side of the rear wheel9.

Here, a fuel supply passage (so-called fuel hose)58for supplying fuel in the fuel tank12to the engine intake system is disposed along the rear frame23at the left side of the vehicle body as shown inFIG. 3.

Describing specifically, the fuel supply passage58is a flexible pipe having flexibility such as a rubber hose or the like, and it is formed of a pipe through which fuel is not permeable. One end58A of the fuel supply passage58is connected to a fuel exit portion provided to the bottom wall of the fuel tank12, and the fuel supply passage58extends from the fuel exit portion to one side in the vehicle width direction (the left side of the vehicle body in this embodiment), and further extends obliquely downwardly along the upper surface of the second rear frame26at the one side in the vehicle width direction. The other end58B of the fuel supply passage58is connected to the engine intake system (the injector65secured to the intake pipe70in this embodiment).

The two-wheeled motor vehicle10is designed as a fuel injection type in which a fuel pump12P is disposed in the fuel tank12and fuel pressurized by the fuel pump12P is supplied to the engine20through the fuel supply passage58and the injector65, however, it may not be designed as the fuel injection type. Even when the two-wheeled motor vehicle10is not designed as the fuel injection type, the layout of the fuel supply passage is identical, and the connection destination of the fuel supply passage may be set not to the injector65, but to a carburetor (fuel supply device).

When this two-wheeled motor vehicle10is provided with an evaporated fuel control device100for preventing evaporated fuel occurring in the fuel tank12from being discharged to the atmosphere, it is difficult to secure a layout space of the evaporated fuel control device100above the fuel tank12because this two-wheeled motor vehicle10has a vehicle layout in which the fuel tank12is located at the upper side of the engine20and the seat11is located above the fuel tank12.

Therefore, the evaporated fuel control device100is mounted in this vehicle as described below.

FIG. 4is a view showing the evaporated fuel control device100together with the peripheral construction thereof when they are viewed from the right side of the vehicle body,FIG. 5is a view of the fuel tank12when the fuel tank is viewed from the upper side, andFIG. 6is a side cross-sectional view of the fuel tank12when the fuel tank12is viewed from the rear side. InFIG. 6, reference character L1represents the center line of the vehicle body which passes through the center in the vehicle width direction.

As shown inFIG. 4, the evaporated fuel control device100has an evaporated fuel passage110which is connected to the fuel tank12at one end thereof and feeds evaporated fuel in the fuel tank12to engine oil in the engine (hereinafter referred to as oil), and an air supply passage120which is opened to the atmosphere at one end thereof and supplies outdoor air into the fuel tank12.

The fuel tank12is configured in a vertically dual-partitioning structure so as to have an upper case12A and a lower case12B, and an oil supply port12C and a gas-liquid separator12D are disposed in the top plate of the upper case12A so as to be spaced from each other at an interval in the front-and-rear direction as shown inFIG. 5. The fuel pump12P is disposed below the oil supply port12C, the fuel pump12P and the gas-liquid separator12D are disposed in the tank12to be apportioned in the front-and-rear direction.

The gas-liquid separator12D is secured in the neighborhood of the rear wall of the back surface of the upper case12A to be nearer to the other side (right wall) in the vehicle width direction. One end of an in-tank pipe111formed of metal or resin (containing rubber) which constitutes a part of the evaporated fuel passage110is joined to this gas-liquid separator12D. One end of the in-tank pipe111is located at a higher position than the upper limit level of the fuel in the fuel tank12.

The one end (in-tank end portion)111A of the in-tank pipe111is joined to the gas-liquid separator12D so as to face the right side of the vehicle body which is the other side in the vehicle width direction, and the in-tank pipe111extends therefrom to the neighborhood of the tank side wall (left wall) in the direction to one side (left side) in the vehicle width direction. Thereafter, the in-tank pipe111is folded back so as to form a curved portion111B convexed to the one side in the vehicle width direction and extends to the neighborhood of the tank side wall (right wall) in the direction to the other side (right side) in the vehicle width direction. Furthermore, the in-tank pipe111is curved rearwards therefrom so as to form a curved portion111C convexed to the other side (right side) in the vehicle width direction, and penetrates through the rear wall of the fuel tank12so that the other end (out-of-tank end portion)111D is opened to the back side.

That is, an S-shaped pipe portion1115which is bent in S-shape between the right and left sides in the vehicle width direction is formed in the in-tank pipe111by the pair of curved portions111B and111C. Therefore, even when the two-wheeled motor vehicle10is tilted to any one of the right and left sides in the vehicle width direction and thus liquid fuel in the fuel tank12flows into the in-tank pipe111, the liquid fuel hardly flows through the S-shaped pipe portion111, and the liquid fuel can be easily returned into the fuel tank12when the two-wheeled motor vehicle10is returned from the tilt.

The out-of-tank pipe112which constitutes the remaining part of the evaporated fuel passage110is joined to the out-of-tank end portion111D. The out-of-tank pipe112is a flexible pipe having flexibility such as a rubber hose or the like, and it is formed of a pipe through which fuel does not permeable.

This out-of-tank pipe112protrudes rearwards from the out-of-tank end portion111D of the in-tank pipe111, curves so as to form a curved portion112A1which faces the other side (right side) in the vehicle width direction and the front side and extends frontwards along the rear frame23at the other side (right side) in the vehicle width direction. The out-of-tank pipe112extends to be tilted downwardly along the rear frame23, and the lower end thereof is joined to the rear upper portion of the crank case62of the engine20.

This out-of-tank pipe112has a first out-of-tank pipe112A joined to the out-of-tank end portion111D of the in-tank pipe111, and a second out-of-tank pipe112B joined to the first out-of-tank pipe112A through a joint part115, and it is supported along the rear frame23by a pair of front and rear clamp members131,132which are provided to the rear frame23at the other side (right side) in the vehicle width direction so as to be spaced from each other at an interval.

Here, the pair of clamp members131,132are pipe holding parts which are secured to the vehicle body2by welding or fastening members such as screws or the like to hold the out-of-tank pipe112on the vehicle body frame2.

The first out-of-tank pipe112A is clamped to the upper surface of the first rear frame25by the single clamp member131provided in the neighborhood of the rear wall of the fuel tank12so as to keep the rearwards convexed curved portion112A1described above. By drawing out rearwards the first out-of-tank pipe112A from the rear wall of the fuel tank12as described above, the dead space between the rear wall of the fuel tank12and the first rear frame25can be effectively used as a pipe space, and also the out-of-tank pipe112can be drawn out to a tank near position at which the first rear frame25is proximate to the fuel tank12, so that the out-of-tank pipe112can be easily laid along the rear frame23.

The first out-of-tank pipe112A extends from the upper surface of the slope portion25A of the first rear frame25to the second rear frame26with being downwardly tilted, and passes over the outside in the vehicle width direction of the second rear frame26in the neighborhood of the joint portion between the first rear frame25and the second rear frame26. The first out-of-tank pipe112A is further drawn to the lower surface of the second rear frame26with being downwardly tilted, extends forwards along the lower surface of the second rear frame26with being downwardly tilted, and joined to the joint part115supported on the lower surface of the second rear frame26.

As the joint part115is used a 3-way joint having a first pipe portion115A which extends linearly and is connectable to pipes at both the ends thereof, and a second pipe portion115B extending from an intermediate position of the first pipe portion115A perpendicularly to the first pipe portion115A, the first pipe portion115A and the second pipe portion115B being integrally with each other. The first out-of-tank pipe112A is joined to one end side of the first pipe portion115A, and the second out-of-tank pipe112B is joined to the other end side thereof. Furthermore, one end of the air supply passage120is connected to the second pipe portion115B.

The remaining clamp member132supporting the out-of-tank pipe112supports the neighboring position to the joint part115in the second out-of-tank pipe112B at the lower surface of the second rear frame26. Accordingly, the joint part115is also held along the lower surface of the second rear frame26.

In this case, as shown inFIGS. 4 and 6, the joint part115is held so that the first pipe portion115A extends in the front-and-rear direction along the lower surface of the second rear frame26, and the second pipe portion115B extends obliquely upwardly along the lower surface of the outside in the vehicle width direction of the second rear frame26.

The second out-of-tank pipe112B extends obliquely downwardly from the other end side of the first pipe portion115A of the joint part115along the second rear frame26, and is joined to the rear end portion of the engine20so as to intercommunicate with oil stocked in the oil pan in the crank case62.

Here,FIG. 3shows the upper limit oil level of oil stocked in the crank case62, and reference numeral20X represents the evaporated fuel passage in the engine20which is joined to the second out-of-tank pipe112B and extends downwardly at the rear wall side in the crank case62.

Reference character HL represents the upper limit oil level of oil stocked in the oil pan under the state that the two-wheeled motor vehicle10is parked on the horizontal surface, character reference LL represents the lower limit oil level of oil under the state that the two-wheeled motor vehicle10is parked on the horizontal surface, and reference character LL2represents an oil level when the two-wheeled motor vehicle10is tilted to a park limit position on a downward slope after oil is put till the lower limit oil level LL under the state that the two-wheeled motor vehicle10is parked on the horizontal surface. The lower end opening20Y of the evaporated fuel passage20X is provided below and in the neighborhood of the oil level (the oil level under park limit) LL2. Accordingly, the lower end opening20Y can be surely located within the oil without disposing the lower end opening20Y at a needlessly low position, and the evaporated fuel which flows from the evaporated fuel passage20X into the engine20is enabled to easily blend into the oil.

As described above, the out-of-tank pipe112is held by only the two clamp members131and132so as to serve as a descending pipe extending along the first rear frame25and further along the second rear frame26, and the descending pipe is joined to the engine20disposed below the second rear frame26with being held. In addition, the whole out-of-tank pipe112can be easily viewed from the outside of the vehicle body, and it can be easily detached and attached.

As shown inFIG. 4, a first check valve117for stopping flow of the fluid from the engine20to the fuel tank12is interposed at some midpoint of the second out-of-tank pipe112B. Accordingly, the evaporated fuel can be allowed to flow from the inside of the fuel tank12through the second out-of-tank pipe112B into the engine20, and also flow of the oil from the inside of the engine20to the fuel tank12can be prohibited in the neighborhood of the engine20. Furthermore, since the first check valve117is provided in the neighborhood of the clamp member132(seeFIG. 4), the first check valve117can be held by the clamp member132, and it is unnecessary to provide a support member dedicated to the first check valve117.

Furthermore, the first check valve117is supported by the second out-of-tank pipe112B with being floated. Therefore, vibration of the engine20hardly transmits, and a special vibration-proof structure or the like is unnecessary.

As shown inFIG. 6, the air supply passage120has a first air supply passage121A extending upwards from the second pipe portion115B of the joint part115, and a second air supply passage121B joined to the first air supply passage121A through a second check valve122. The air supply passage120extends upwards from the second pipe portion115B of the joint part115, and the upper end (ambient air open end)121C thereof is opened to a side (the right side) of the fuel tank12to intercommunicate with the atmosphere.

Specifically, the first and second air supply passages121A and121B are formed of flexible pipes having flexibility such as rubber hoses or the like. As shown inFIG. 6, the first air supply passage121A passes from the second pipe portion115B of the joint part115over the outside in the vehicle width direction of the second rear frame26, passes over the outside in the vehicle width direction of the tank support bracket41, and is supported by a single clamp member135provided to the tank support bracket41. Accordingly, as shown inFIG. 4, the first air supply passage121A extends from the joint part115to the upper rear side, and the upper portion thereof is held between the tank support bracket41, the downwards extending stay42and the second rear frame26.

The lower end of the second check valve122is joined to the upper end of the first air supply passage121A, and the lower end of the second air supply passage121B is joined to the upper end of the second check valve122. The second check valve122is a check valve for stopping flow from the fuel tank12to the outside air. The second air supply passage121B is formed to be shorter than the first air supply passage121A, and supported by a single clamp member137provided to the side wall of the fuel tank12with being placed face up.

In this case, as shown inFIG. 6, the upper end (ambient air open end)121C of the second air supply passage121B is located below a flange portion12F extending around the joint portion between the upper case12A and the lower case12B of the fuel tank12. Therefore, intrusion of dust from the upper side can be prevented by the flange portion12F, and also the air supply passage120can be disposed by using a narrow gap (dead space) between the flange portion12F and a rear side cover53which is disposed proximately to the side of the fuel tank12.

Furthermore, since the second check valve122is located between the pair of upper and lower clamp members135and136for supporting the air supply passage120, the second check valve122is also positioned by the clamp members135and136. In this case, the second check valve122is positioned between the fuel tank12and the tank support portion bracket41, and the gap (dead space) between these parts can be used as a layout space for the second check valve122, so that the sideward protrusion of the second check valve122can be suppressed.

Still furthermore, the second check valve122is supported by the second air supply passage121B with being floated, so that vibration of the engine20hardly transmits. Therefore, a special vibration-proof structure or the like is unnecessary.

Next, the flow of the evaporated fuel by the evaporated fuel control device will be described.

When a part of the fuel in the fuel tank12evaporates and the internal pressure of the fuel tank12increases to be higher than the outdoor air pressure (positive pressure), the evaporated fuel passes through the gas-liquid separator12D, flows into the in-tank pipe111, passes through the in-tank pipe111and enters the out-of-tank pipe112. In this case, the first check valve117provided to the out-of-tank pipe112is set to an open state, so that the evaporated fuel flows through the out-of-tank pipe112and the joint part115into the oil in the engine20, whereby the evaporated fuel can be made to blend into the oil.

On the other hand, when the internal pressure of the fuel tank12decreases to be less than the outdoor air temperature (negative pressure), the second check valve122provided to the air supply passage120is set to an open state, so that the outdoor air intrudes from the outdoor air open end121C into the air supply passage120, successively flows through the air supply passage120, the joint part115and a part of the evaporated fuel passage110(the first out-of-tank pipe112A and the in-tank pipe111) in this order, and flows into the fuel tank12, whereby the internal pressure of the fuel tank12can be adjusted to the atmosphere pressure.

As shown inFIG. 2, the two-wheeled motor vehicle10is provided with a return passage141for connecting a head cover610of the engine20and an air cleaner unit72.

This return passage141is formed in the head cover61C. A valve driving chamber intercommunicating with the inside of the crank case62and the inside of the air cleaner unit72(air cleaning chamber) are made to intercommunicate with each other through the return passage141. Accordingly, evaporated fuel occurring in the crank case62(evaporated fuel generated when the fuel blending in the oil is evaporated, and blow-by gas) is supplied through the air cleaner unit72to the engine intake system, whereby the two-wheeled motor vehicle10is configured so that the evaporated fuel in the crank case62is not discharged to the atmosphere.

FIG. 7shows a state that the lid53A provided to the rear side cover53at the right side of the vehicle body is detached. As shown inFIG. 7, when the lid53A is detached, a part of the evaporated fuel control device100is exposed from the opening portion53B provided to the rear side cover53, whereby it is possible to access the evaporated fuel control device100. In this construction, the portion (the air supply passage120) provided to the side wall of the fuel tank12is exposed as shown inFIG. 7. Therefore, various kinds of maintenance such as status check and cleaning of the outdoor air open end121C and the second air supply passage121B can be performed.

As described above, according to this embodiment, in the vehicle layout in which the fuel tank12is located at a higher position than the engine20, the evaporated fuel passage110is routed as a descending passage from the fuel tank12to the engine20, and the air supply passage120is joined to a halfway position of the evaporated fuel passage110which is located at the fuel tank12side with respect to the first check valve117and positionally lower than the uppermost portion of the fuel tank12, so that the air supply passage120can be laid out without being disposed at a higher position than the fuel tank12.

Under this layout, a part of the evaporated fuel passage110(the first out-of-tank pipe112A and the in-tank pipe111), that is, a part of the evaporated fuel passage110which is located at the fuel tank12side with respect to the joint portion (corresponding to the joint part115) to which the air supply passage120is joined also serves as the air supply passage120, so that the air supply passage120can be shortened.

Furthermore, even when liquid fuel flows from the fuel tank12into the evaporated fuel passage110, the liquid fuel more easily flows to the engine20side as compared with the joint portion (joint part115) of the air supply passage120because the evaporated fuel passage110serves as a descending passage. Therefore, the air supply passage120and the part of the evaporated fuel passage110which also serves as the air supply passage120are easily kept under the state that they intercommunicate with each other, so that the inside of the fuel tank12can be adjusted to the atmosphere pressure.

As described above, according to this construction, the air supply passage120is laid out without being disposed at a higher position than the fuel tank12. Therefore, even when a seat layout is set so that the seat11on which a driver sits covers the upper surface of the fuel tank12, it is unnecessary to secure the space for the air supply passage120between the seat11and the fuel tank12. Therefore, the seat can be set at a low position as in the case of a vehicle having no evaporated fuel control device100.

Furthermore, in this construction, after the evaporated fuel passage protrudes rearwards from the fuel tank12, it is disposed along the rear frame23at the right side and connected to the engine20. Therefore, the evaporated fuel passage110can be routed by using the rear frame23.

In addition, in this construction, the fuel supply passage58for supplying fuel from the fuel tank12to the engine intake system is disposed along the rear frame23at the left side. Therefore, the fuel supply passage58and the evaporated fuel passage110are disposed to be allocated to the right and left sides, so that they can be easily assembled.

Furthermore, in this construction, the air supply passage120is routed at the same side as the evaporated fuel passage110in the vehicle width direction. Therefore, the air supply passage120can be assembled from the same side, so that the attaching/detaching performance and maintenance performance of the whole evaporated fuel control device100can be enhanced.

In this construction, the air supply passage120extends upwards from the rear frame23and extends upwards along the tank support bracket41for supporting the fuel tank12, and also the air supply passage120is clamped and supported by the tank support bracket41and the fuel tank12. Therefore, the air supply passage120can be supported by using an existing part, so that increase of the number of parts can be avoided.

Furthermore, the second check valve122is disposed between the tank support bracket41and the fuel tank12, and the air supply passage120is supported on the fuel tank12at an open end side thereof with respect to the second check valve122of the air supply passage120. Therefore, the second check valve122can be disposed by using the dead space between the tank support bracket41and the fuel tank12, and the outdoor air open end121C of the air supply passage120can be surely positioned on the side surface of the fuel tank12so that the air supply passage120can be opened to the atmosphere.

Still furthermore, in this construction, the fuel tank12is located at a substantially middle position between the front wheel7and the rear wheel9in the vehicle travel direction. Therefore, the fuel tank12and the outdoor air open end121C of the air supply passage120can be disposed to be far away from the front and rear wheels at which dust is easily raised, and also to be relatively distant from the ground surface.

Furthermore, the first check valve117is disposed at the upper side of the crank case62which is positionally overlapped with the engine20in top view (seeFIG. 6). Therefore, when oil from the engine20exists in the first check valve117, the fluidity of the oil is increased by heat ascending from the engine20to enable the oil from easily return to the engine20side. When liquid fuel exists in the first check valve117, the liquid fuel can be positively evaporated by the heat of the engine20.

The embodiment described above is merely an example of the present invention, and any modification and application may be made without departing from the subject matter of the present invention. For example, in the above embodiment, the evaporated fuel control device100is disposed at the right side of the vehicle body, and the fuel supply passage58is disposed at the left side of the vehicle body. However, the present invention is not limited to this style, and they may be disposed while right and left are reversed. Furthermore, in the above embodiment, the evaporated fuel passage110is disposed along the second rear frame26at any one of the right and left sides, and the fuel supply passage58is disposed along the second rear frame26at the other side. In short, they may be disposed along the rear frame23, and they may be disposed along the first rear frames25.

Furthermore, in the above embodiment, the air supply passage120is clamped and supported by the tank support bracket41and the fuel tank12. However, the air supply passage120may be supported by any one of the tank support bracket41and the fuel tank12.

Still furthermore, in the above embodiment, the present invention is applied to the evaporated fuel control device100of the two-wheeled motor vehicle10shown inFIG. 1. However, the present invention is not limited to this style, and the present invention may be applied to an evaporated fuel control device of another saddle-type vehicle. The saddle-type vehicles contain all types of vehicles in which a rider gets on a vehicle while straddling the vehicle body, and they contain not only two-wheeled motor vehicles (containing scooter type vehicles), but also three-wheeled vehicles and four-wheeled vehicles which are classified as ATV (All-Terrain Vehicle).

DESCRIPTION OF REFERENCE NUMERALS