A saddle-type vehicle that securely supports a fuel tank with sufficient strength when load in a vertical direction is applied. A pair of frame members extend in a front-and-rear direction of the vehicle and support a fuel tank. The fuel tank has a pair of flanges contacting the outer sides of the frame members. The flanges are attached to the frame members by attachment members inserted from outside in a vehicle width direction.

RELATED APPLICATIONS

This application claims the benefit of priority under 35 USC 119 of Japanese patent application no. 2005-249311, filed on Aug. 30, 2005, which application is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a saddle-type vehicle including left and right frame members extending in a front-and-rear direction of the vehicle and a fuel tank supported by the frame members.

2. Description of Related Art

A typical saddle-type vehicle, such as a motorcycle, has left and right frame members extending from a head pipe toward the rear of the vehicle, a fuel tank placed on the frame members, and a saddle-type seat disposed behind the fuel tank.

A typical structure for attaching the fuel tank in a motorcycle of this type is disclosed in JP-A-6-234382. According to this structure, substantially U-shaped brackets (19) which are open to the front are fixed to the left and right side walls of the fuel tank. The left and right brackets (19) engage with positioning members (21) fixed to left and right frame members (20). Under this condition, the rear end of the fuel tank is secured to the frame members by bolts.

In the motorcycle of JP-A-6-234382, each of the positioning members (21) of the left and right frame members is sandwiched between an upper side (19a) and a lower side (19b) of the corresponding bracket (19) of the fuel tank. Thus, load in a vertical direction generated from a road surface expands the distance between the upper side (19a) and the lower side (19b). In extreme cases, the load causes deformation of the brackets. To overcome this drawback, a reinforcing material such as a patch can be added to the structure. In this case, however, the number of components increases and the cost rises.

SUMMARY OF THE INVENTION

The invention has been developed to solve the above problems. It is an object of the invention to provide a saddle-type vehicle capable of securely supporting a fuel tank with sufficient strength when load in the vertical direction is applied.

A saddle-type vehicle according to the invention includes a pair of frame members extending in a front-and-rear direction of the vehicle, and a fuel tank supported by the frame members. The fuel tank has a pair of flanges contacting outer sides of the frame members and attached to the frame members by attachment members inserted from outside in a vehicle width direction.

In the saddle-type vehicle according to the invention, the flanges of the fuel tank contact the outer sides of the frame members, and the flanges are attached to the frame members by attachment members inserted from outside in a vehicle width direction. Thus, load acting to bend the flanges is reduced and deformation of the flanges is avoided. Accordingly, the fuel tank is securely supported with sufficient strength.

In the saddle-type vehicle according to the invention, the flanges of the fuel tank are directly attached to the outer sides of the frame members. Accordingly, the numbers of required components and assembly processes are decreased and the cost is lowered compared with a case in which intermediate components are interposed or additional reinforcing members are equipped.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention is hereinafter described with reference to the appended drawings.

FIGS. 1-10show a saddle-type vehicle in an embodiment according to the invention. In this embodiment, a motorcycle on which a saddle-type seat is placed is discussed. The front-and-rear direction and left-and-right direction in this embodiment refer to the front-and-rear direction and left- and right direction as viewed by a person sitting on the seat.

In these figures, a motorcycle1is shown. The motorcycle1includes a backbone-type vehicle body frame2, an engine unit (not shown) supported by the vehicle body frame2, a front fork4supported by a head pipe3formed integrally with the front end of the frame2such that the front fork4can freely turn to the left and right, and a rear arm5supported by the rear end of the vehicle body frame2such that the rear frame5can freely swing upward and downward. A front wheel6is supported by the lower end of the front fork4, and handlebars (not shown) are fixed to the upper end of the front fork4. A rear wheel7is supported by the rear end of the rear arm6.

The vehicle body frame2has a pair of left and right frame members8,8extending from the head pipe3to the rear of the vehicle while expanding outward in the vehicle width direction; left and right rear arm brackets9,9extending downward substantially in the vertical direction from the rear ends of the left and right frame members8,8; and left and right seat rails10,10and left and right seat stays13,13extending diagonally upward to the rear of the vehicle from the left and right rear arm brackets9.

A fuel tank11is mounted on the left and right frame members8. A saddle-type seat12on which a rider sits astride is placed on the left and right seat rails10behind the fuel tank11. An engine unit (not shown) is suspended by the left and right frame members8and rear arm brackets9. The rear arm6is supported by the lower ends of the rear arm brackets9via a pivot shaft9a.

In the fuel tank11, a fuel tank injection port18ais provided on an upper wall of a tank main body18which is formed by oil-tightly combining peripheral edges16cand17cof lower tank half body16and higher tank half body17, respectively, by welding. The fuel injection port18ais opened and closed by a fuel cap19.

The upper tank half body17is substantially bowl-shaped largely expanding in the upward direction. The rear part of a bottom wall16aof the lower tank half body16is substantially flat. The bottom wall16ais bent such that it rises from the rear part to the front. A pump attachment opening16bis formed at the lowermost position in the rear part of the bottom wall16a. A not-shown air cleaner is disposed within a space a formed below the front part of the bottom wall16aof the lower tank half body16(seeFIGS. 4 and 10(a)-(c)).

A fuel pump unit20is disposed within the tank main body18. As illustrated inFIG. 5, the fuel pump unit20is inserted into the tank from below through the pump attachment opening16b, and an attachment flange20ais detachably fixed to the opening peripheral edge of the pump attachment opening16bby a bolt via a seal member21. A fuel supplying port20bis provided on the bottom face of the fuel pump unit20. A fuel hose20cfor supplying fuel to a fuel injection valve (not shown) is connected to the supplying port20b.

An attachment bracket23is attached to a rear wall18eof the tank main body18. The fuel tank11is supported by the vehicle body frame2via a supporting member22, which is inserted into the attachment bracket23in the vehicle width direction, such that the fuel tank11can vertically swing. More specifically, the following structure is employed.

As illustrated inFIGS. 5 and 9, the attachment bracket23has a base23afixed to the rear wall18e, left and right side pieces23b,23bprojecting from the base23atoward the rear, and an upper side piece23cconnecting the upper ends of the left and right side pieces23b. The attachment bracket23on the rear wall18eis covered by the front end of the seat12and cannot be seen from outside.

The supporting member22is disposed on the cross member24connecting the left and right seat rails10. The supporting member22has a U-shaped supporting portion25which is open to below and fixed to the cross member24, a rubber damper (elastic portion)26disposed within the supporting portion25, a collar27inserted into the rubber damper26in the vehicle width direction, and a bolt28inserted into the collar27from the outer side of the vehicle.

The bolt28is inserted into the collar27such that the bolt28penetrates through the left and right side pieces23bof the attachment bracket23. Then, a nut28ais attached to the bolt28and tightened to fix the fuel tank11such that the fuel tank can vertically swing.

A front side flange18b, left and right side flanges18c, and a rear side flange18dare constituted by the peripheral edges16cand17cof the lower and upper tank half bodies16and17.

The left and right side flanges18cand the rear side flange18dproject downward along the lower end of the tank main body18. The front side flange18bextends upward from the front ends of the left and right flanges18c,18cand projects frontward. As illustrated inFIG. 4, the front side flange18bhas a circular-arc shape which extends from the upper side to the left and right sides and expands in the vehicle width direction in the lower part as viewed in lateral cross-section.

The lower portion of the front side flange18bextends toward the front covering the outer sides of the left and right frame members8,8. Extensions as frame attachment members18b′ are provided at the left and right ends of the front side flange18b.

The left and right frame attachment members18b′ are inclined such that the distance between the frame attachment members18b′ at the lower position is larger in the vehicle width direction than that at the upper position.

The left and right frame attachment members18b′ of the fuel tank11are attached to the outer sides of the left and right frame members8,8by tightening bolts (attachment members)30,30with dampers (damping members)31,31interposed between the frame members8,8and the bolts30,30. More specifically, the following structure is employed.

The left and right frame members8,8have oblong rectangular shapes in the lateral cross section. Bosses8a,8aprojecting outward in the vehicle width direction are formed integrally with the outer sides of the left and right frame members8. The outer end faces of the left and right bosses8aare inclined such that the distance between the bosses8aat the lower position is larger than that at the upper position and extend in parallel with the frame members18b′.

Each of the left and right dampers31attached to the bosses8ahas a rubber damper main body (elastic member)32, and a metal collar member33inserted into the damper main body32.

The damper main body32has a cylindrical member32ainserted into the boss hole8b, and a flange member32bformed integrally with the outer peripheral edge of one end of the cylindrical member32a.

As illustrated inFIG. 6, the collar member33has a cylindrical body33awhich is inserted into the cylindrical member32aand has a screw hole33c, and a flange body33bwhich is formed at the outer peripheral edge of one end of the cylindrical body33aand contacts the flange member32b.

A rotation preventing member33cwhich extends outward in the radius direction is formed integrally with the flange body33b. The rotation preventing member33cprojects toward the front from the front edge of the frame attachment member18b′. A bended engaging member33c′ engaging with the front edge of the frame attachment member18b′ is formed at the front end of the rotation preventing member33c. When the tightening bolt30is screwed and the collar member33is rotated, the rotation preventing member33ccomes into contact with the front edge of the frame attachment member18b′. As a result, rotation of the collar member33is stopped.

A positioning member33dextending outward in the radius direction is formed integrally with the flange body33b. The positioning member33dprojects downward below the lower edge of the frame attachment member18b′. A bended supporting member33d′ which can contact the lower edge of the frame attachment member18b′ is formed at the lower end of the positioning member33d. Each of the frame attachment members18b′ and the dampers31can be positioned by placing the fuel tank11from above the frame and bringing the lower edges of the left and right frame attachment members18b′ into contact with the positioning members33d.

The fuel tank11is fixed to the bosses8aof the left and right frame members8by screwing the tightening bolts30into the screw holes33con the cylindrical bodies33aof the collar members33from the outer sides in the vehicle width direction via the frame attachment members18b′. Washers34are also provided.

For fitting the fuel tank11to the vehicle body frame2, the dampers31are initially attached to the left and right bosses8a. Then, the fuel tank11is placed on the left and right frame members8from above, and simultaneously the attachment bracket23is brought into engagement with the supporting member22. Under this condition, the bolt28is inserted from the left side to temporarily hold the attachment bracket23by the supporting member22. Then, the front part of the fuel tank11is pivoted downward around the bolt28, and the lower edges of the left and right attachment frames18b′ are brought into contact with the positioning members33dto position the fuel tank11.

In this structure, the left and right frame attachment members18b′ of the fuel tank11are diagonally disposed such that the distance between the frame attachment members18b′ at the lower position is larger than that at the upper position, and the outer end faces of the left and right bosses8aare inclined at the same angles. Thus, the fuel tank11can be appropriately attached even when a certain dimensional error is produced between the attachment members18band the bosses8a.

Next, the tightening bolts30are screwed into the collar members33from the outer left and right sides via the left and right attachment members18b′ to be tightened, and the bolt28is also tightened. Since the left and right frame attachment members18b′ are positioned in the vertical direction by the positioning members33d, the attachment members18b′ and the collar members33are easily centered. When the collar members33are rotated at the time of tightening the tightening bolts30, the rotation preventing members33ccome into contact with the front edges of the attachment members18b′ and thus rotation of the collar members33is stopped.

The front region of the fuel tank11is covered by a resin tank cover40as a component constituting the external appearance. The tank cover40covers the front end of the tank main body18including the front side flange18band the left and right attachment members18b′, and forms a surface continuing from the tank main body18.

The tank cover40is fixed to the tank main body18and the vehicle body frame2, and has the following structure described in detail.

A claw40awhich engages with a gate-shaped positioning piece18fformed at the front end face of the tank main body18is provided on the inner surface of the upper wall of the tank cover40. The movements of the tank cover40in the up-and-down direction, left-and-right direction, and the rearward direction are prevented by the engagement between the claw40aand the positioning piece18f.

A front attachment seat40bis concaved on the front wall of the tank cover40. The front attachment seat40band a fixing bracket41of the air cleaner (not shown) disposed below the tank main body18are co-tightened by a bolt42to be fixed to a frame connecting member3aof the head pipe3. Since the tank cover40and the fixing bracket41of the air cleaner are co-tightened and fixed to the frame connecting member3aof the rigid head pipe3, the attachment rigidities of the tank cover40and the fixing bracket41can be enhanced.

Stepped left and right attachment seats40c,40care formed on the left and right side walls of the tank cover40. The left and right attachment seats40care fixed to extensions17c′ extending from the front side flange18bby bolts44via rubber dampers43. The left and right lower ends of the tank cover40are fixed to attachment pieces46joined to the tank main body18by bolts45.

In this embodiment, the left and right frame attachment members18b′ of the front side flange18bof the fuel tank11are brought into contact with the outer end faces of the bosses8aformed on the outer sides of the left and right frame members8,8, and the left and right attachment members18b′ are fixed to the bosses8aby tightening bolts30inserted from outer sides in the vehicle width direction. Thus, load generated from the road surface in the vertical direction is prevented from acting on the left and right attachment members18b′ in the bending directions. Accordingly, deformation of the front flange18bis avoided, and the strength for supporting the fuel tank11is secured.

In this embodiment, the left and right attachment members18b′ of the fuel tank11are directly attached to the bosses8aof the left and right frame members8. Since additional intermediate stays or reinforcing components are unnecessary, the numbers of the required components and assembly processes are not increased and thus the cost is not raised.

In this embodiment, the dampers31, each of which has a rubber damper main body32and a collar member33attached to the damper main body32, are fitted to the bosses8aof the left and right frame members8, and the tightening bolts30are tightened and fixed to the collar members33via the left and right attachment members18b′ of the fuel tank11. Since the fuel tank11is elastically supported by the frame members8via the dampers31, vibration generated from the road surface is not transmitted to the fuel tank11.

In this embodiment, the rotation preventing members33cwhich prevent rotation of the collar members33by contacting the front edges of the attachment members18b′ are provided on the collar members33. Accordingly, rotation of the collar members33is stopped at the time of tightening the tightening bolts30, and thus the attachment members18b′ are securely fixed to the bosses8a.

In this embodiment, the positioning members33dfor positioning the fuel tank11in the vertical direction are provided on the collar members33. Accordingly, the fuel tank11is easily positioned at the time of attaching the fuel tank11to the frame members8,8from above, and thus the work efficiency is enhanced.

In this embodiment, the outer end faces of the left and right attachment members18b′ and the left and right bosses8aare diagonally disposed such that the distances between the left and right attachment members18b′ and between the left and right bosses8aare larger at the lower position than those at the upper position. Accordingly, a certain dimensional error between the attachment members18b′ and the bosses8aat the time of attachment of the fuel tank11from above the frame can be absorbed, and thus the fuel tank11is easily and securely fitted.

In this embodiment, the attachment bracket23is fixed to the rear wall18eof the fuel tank11, and the bracket23is supported in such a manner as to be movable in the upward and downward directions by the bolt28inserted in the vehicle width direction via the supporting member22secured to the vehicle body frame2. Thus, assembly of the fuel tank11is easily carried out by pivoting the front part of the fuel tank11from the upper position to the lower position around the bolt28. Moreover, since the supporting member22is made of elastic material, transmission of vibration generated from the road surface to the fuel tank11is avoided.

Since the front side flange18bincluding the left and right attachment members18b′ of the fuel tank11is covered by the tank cover40, deterioration of the external appearance caused by exposure of the attachment members of the fuel tank11to the outside is avoided.

While the invention has been described primarily with respect to a motorcycle, the invention encompasses other saddle-type vehicles such as a small three-wheel or four-wheel vehicle, an ATV (all terrain vehicle), a snowmobile, and other saddle-type vehicles. Thus, the invention is applicable to any vehicles that have a saddle-type seat on which a rider sits astride.

The particular embodiments of the invention described in this document should be considered illustrative, rather than restrictive. Modification to the described embodiments may be made without departing from the spirit of the invention as defined by the following claims.