Structure of fuel pump installation area for two-wheeled vehicle

A fuel pump installation area for a vehicle for enhancing the stiffness of the fuel pump built in a fuel tank and for enhancing the stiffness of an installation area of a tank installation stay on the fuel tank side. In a motorcycle in which a fuel tank is installed to the body frame and a fuel pump is provided within this fuel tank, the fuel pump is installed to the fuel tank via a pump installation member. To the pump installation member, a tank installation stay for fixing the fuel tank to the body frame is installed. The left and right side walls may be formed by depressing the center of the underside of the fuel tank upwardly over the front and the rear. Concave-shaped engaging members are installed by engaging left and right convex portions provided on the body frame with these engaging members, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 USC 119 to Japanese Patent Application Nos. 2003-282204 and 2003-282206 both filed on Jul. 29, 2003 the entire contents thereof are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to structure of a fuel pump installation area for a two-wheeled vehicle.

2. Description of Background Art

Conventionally, as the structure of a fuel pump installation area for a two-wheeled vehicle, there is known a structure in which a fuel pump is arranged within a fuel tank and installed on a bottom wall of the fuel tank. See, for example, Japanese Patent Laid-Open No. 2000-72074.

FIG. 2 of Japanese Patent Laid-Open No. 2000-72074 will be explained with reference toFIG. 15of the attached drawings. In this respect, the reference numerals have been re-designated.

FIG. 15is a cross-sectional view showing conventional structure of a fuel pump installation area for a two-wheeled vehicle wherein a fuel pump unit303has been arranged within a fuel tank300by installing a cup302on a bottom301, located in the rear of the fuel tank300, that is curved in a convex shape downwardly and installing the fuel pump unit303onto this cup302.

InFIG. 15, a main frame305is provided for constituting a body frame306;307, a fuel tank installation stay for installing the rear portion of the fuel tank300on the body frame306side;311, an engine; and312,313, a throttle body and an air cleaner which are air intake system parts installed to the engine311, respectively.

The fuel pump unit303is long and narrow in shape with one end portion being mounted to the cup302. However, the fuel pump unit303is equipped with articles that have a weight such as a motor. Therefore, a large moment occurs on the fuel pump unit303when the vehicle is in operation. Accordingly, in order to support this moment, the cup302and the bottom301of the fuel tank300require a high stiffness.

Also, although the fuel tank installation stay307has been directly installed to the bottom301of the fuel tank300, the bottom301requires a high stiffness in order to support the fuel tank300filled with fuel.

Conventionally, a structure for installing a fuel tank on a two-wheeled vehicle, is known wherein on an inner wall of the front part of the fuel tank there is provided a concave portion with a body frame being provided with a convex portion. The convex portion is caused to engage with the concave portion to thereby install the fuel tank. See, for example, Japanese Patent No. 3370888.

FIG. 7 of Japanese Patent No. 3370888 will be explained with reference to the followingFIG. 16. In this respect, inFIG. 16, only the upper half part of FIG. 7 of Japanese Patent No. 3370888 is shown, and reference numerals have been re-designated.

FIG. 16is a front view partially cross-sectional view) of principal part showing a conventional structure for installing a fuel tank for a two-wheeled vehicle. A left inside plate1302of a left tank portion1301is provided on the fuel tank1300and a right inside plate1304of a right tank portion1303is provided. An engaging member1306is installed, respectively; in the lower part of a main frame1307. A gusset1308is installed and to this gusset1308, a spindle1311for extending from side to side is installed so as to penetrate therethrough. A rubber shock absorbing member1312is fitted in both end portions of this spindle1311, respectively. The rubber shock absorbing members1312,1312are caused to engage with those engaging members1306,1306on the fuel tank1300side. In this respect, a concave portion1313is formed between the left and right inside plates1302,1304of the fuel tank1300.

In a case of installing the above-described engaging members1306to the left and right inside plates1302,1304of the fuel tank1300by welding, if a distance between the left and right inside plates1302,1304is small, it will become difficult to insert, within the concave portion1313, a welding jig for positioning or fixing the engaging member1306in advance on a welder or the fuel tank1300during welding. Thus, the workability during welding will be degraded. Further, if the distance between the left and right inside plates1302,1304is made larger, the capacity of the fuel tank1300will be reduced. If there is made an attempt to secure the capacity of the fuel tank1300, the fuel tank1300will become large-sized.

Also, in order to reduce the cost, there is a demand for applying the same engaging members1306to different types of two-wheeled vehicles. If usable for other vehicle types by a slight change even if not the same engaging members, the cost will be able to be reduced. Further, if setting (for example, size) of the rubber shock absorbing member1312could be simply changed by a slight change in the engaging member1306depending upon the vehicle type, a condition suitable for the vehicle type will be obtained, which is more preferable.

SUMMARY AND OBJECTS OF THE INVENTION

It is an object of the present invention to enhance the stiffness of an installation area of a fuel pump built in the fuel tank to the fuel tank, and to enhance also the stiffness of an installation area of the tank installation stay on the fuel tank side concerning the structure of a fuel pump installation area for a two-wheeled vehicle.

According to the present invention, there is provided a two-wheeled vehicle in which a fuel tank is installed on a body frame and a fuel pump is provided within this fuel tank. The fuel pump is installed on the fuel tank via a pump installation member and to this pump installation member, a tank installation stay for fixing the fuel tank to the body frame is installed.

The present invention provides an axis of a cylinder of an engine arranged below the fuel tank that is caused to stand up, an air intake system part for extending toward the rear is installed to the rear of the cylinder. The pump installation member and the tank installation stay are arranged substantially above the air intake system part.

In the present invention, since the fuel pump is installed on the fuel tank via the pump installation member and to this pump installation member, the tank installation stay has been installed, as compared with, for example, a case where the fuel pump has been directly installed to the bottom wall of the fuel tank, the stiffness of the fuel pump installation area can be enhanced by the pump installation member. By installing the tank installation stay to such a fuel pump installation area with enhanced stiffness, the stiffness of the fuel pump installation area can be further enhanced, and stiffness of the installation area of the tank installation stay onto the fuel tank side can be also enhanced. Therefore, the fuel pump can be further reliably supported and sound vibration performance of the vehicle can be improved.

According to the present invention, the engine in which the axis of the cylinder has been caused to stand up is shaped such that the front part of the bottom wall of the fuel tank is depressed upwardly and the rear part of the bottom wall of the fuel tank bulges downwardly. In an engine in which the fuel pump has been arranged within the fuel tank, the fuel pump is to be installed in the rear part of the bottom wall at the lowest position of portions of the fuel tank. Further, if the air intake system parts extends toward the rear from the engine, the rear part of the bottom wall of the fuel tank which is located above the air intake system parts will become substantially flat, and the pump installation member will become substantially flush with the tank installation stay so that it becomes possible to combine by making them to come in close proximity to each other. If the pump installation member comes in close proximity to the tank installation stay, it will be possible to shorten the tank installation stay, and to firmly install the fuel tank to the body frame side. Also, the weight of the tank installation stay will be able to be saved.

It is a problem of the present invention to prevent, concerning the structure for installing a fuel tank for a two-wheeled vehicle, the fuel tank from becoming large-sized while securing the capacity thereof, and to enhance general-purpose properties of an installation member for installing the fuel tank to the body frame. Further the present invention makes it possible to perform a slight change in the installation member while restraining the cost from increasing.

According to the present invention, there is provided a structure for installing a body frame for a two-wheeled vehicle in which on left and right inner walls caused by depressing the center of the underside of the fuel tank upwardly over the front and the rear, concave-shaped engaging members are installed, respectively; and the fuel tank is installed to the body frame by engaging left and right convex portions provided on the body frame with these engaging members, respectively. Each engaging member is constructed of two members, a base member welded to the fuel tank and an engaging body and an engaging body for fastening to this base member by means of fastening means.

The present invention includes a concave portion to be provided on the engaging member that is constructed of a first concave portion provided on the base member and a second concave portion provided on the engaging body.

The present invention includes a tank-side rear part installation area provided in the rear of the fuel tank that is constructed such that a tank installation stay for integrally extending from a pump installation member for installing a fuel pump arranged within the fuel tank to the fuel tank is installed to the body frame.

In the present invention aim1, since the engaging member is constructed of two members, a base member welded to the fuel tank and an engaging body for fastening to this base member by means of fastening means, it is possible to reduce a size of the base member of the present invention to be smaller than the conventional engaging member. In a case of installing the base member to the fuel tank by welding it is easy to insert a welding jig or a welder for positioning or fixing the base member on left and right inner walls inside the fuel tank without interfering with the left and right inner walls.

Accordingly, the workability of the base member during welding can be enhanced, and the capacity of the fuel tank can be secured, or the fuel tank can be prevented from becoming large-sized. Further, since the base member can be made of a small-size, the same engaging member can be installed to fuel tanks for different types of two-wheeled vehicles, and general-purpose properties can be enhanced. When changing a shape of the engaging member depending upon the vehicle type, it is possible to change only one of the base member and the engaging body, to apply the other, and to restrain the cost from increasing.

In the present invention, since the concave portion of the engaging member is constructed of a first concave portion of the base member and a second concave portion of the engaging body, it is possible to prevent the second concave portion from becoming large-sized as compared with, for example, an engaging member, the concave portion of which is constructed of only the second concave portion.

In the present invention, since the tank-side rear part installation area in the rear of the fuel tank has been constructed such that the tank installation stay for integrally extending from the pump installation member is installed to the body frame, the strength/stiffness of the tank-side rear part installation area can be enhanced by the pump installation member and the tank installation stay without increasing a number of parts of the tank-side rear part installation area of the fuel tank as compared with the conventional case even if the engaging member of the fuel tank front part is made into two-parts divided structure. This becomes preferable as the structure for installing the fuel tank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, with reference to the accompanying drawings, the description will be made of the best mode for carrying out the present invention. In this respect, the drawings will be viewed in the direction of the symbol.

FIG. 1is a side view showing a two-wheeled vehicle according to the present invention. A motorcycle10is a vehicle including a head pipe12provided in the front part of a cradle type body frame11with a front fork13installed in such a manner as to be freely steered. At the lower end of this front fork13, a front wheel14is installed. On the upper part of the front fork13, handlebars16are installed. On the inside of the body frame11, an engine18is installed. In the lower part of the rear part of the body frame11, a swing arm21is installed in such a manner as to be freely swingable in the up-and-down direction. At the rear end of the swing arm21, a rear wheel22is installed. Between the upper part of the rear part of the body frame11and the rear part of the swing arm21, a pair of left and right rear shock absorber units23,24(only a symbol23on this side is shown) are mounted. On the upper part of the body frame11, a fuel tank25made of aluminum alloy is installed. In addition, an axis26of the head pipe12is provided.

The engine18is an engine in which each cylinder has been arranged in a direction of the vehicle width as a series four-cylinder engine, and is composed of a crankcase31and a cylinder portion32substantially vertically installed to the front part of the crankcase31. In the engine18, from the front part of the cylinder head33for constituting the cylinder portion32, exhaust pipes35,36,37,38(here, only exhaust pipes35,36are shown) extend downwardly toward the front for each cylinder. In the rear part of the cylinder head33, a carburetor41and an air cleaner42are installed in order; and the engine is installed to the body frame11by means of a front engine hanger43, a rear upper engine hanger44and a rear engine hanger46.

An axis47is illustrated for each cylinder of the engine18. The axis47is caused to intersect an axis26of the head pipe12, in other words, the axis47is caused to point upwardly of the head pipe12, whereby the cylinder portion32has been set to a substantially upright standing state.

The fuel tank25is a part installed to a front part installation area48and a rear part installation area51provided on the body frame11.

An upper case56and a lower case57are provided for constituting the crankcase31respectively. A self-starter58and a battery61are installed to the upper part of the rear part of the crankcase31, respectively. A cover62is provided for an AC generator for projecting from the crankcase31sideways of the vehicle body. A crankshaft63is operatively connected to the engine with a water pump64installed on the side surface of the crankcase31. A counter shaft66and an output shaft67are provided on a transmission68integrally provided in the rear part of the engine18, respectively. A drive sprocket71is installed on the output shaft67with a chain72operatively positioned between a driven sprocket73integrally installed to the rear wheel22and a drive sprocket71.

An upper cowl75is provided for covering the front part of the upper part of the motorcycle10. A front fender76is provided for covering the upper part of the front wheel14. A radiator77is provided for cooling the engine18. An oil cooler78is installed on the lower part of the front part of the engine18. An oil element81is installed on an oil cooler78. A rear exhaust pipe82is connected to each exhaust pipe35to38. A muffler83is connected to the rear exhaust pipe82. An under cowl84is provided for covering the lower parts of the engine18, the exhaust pipes35to38and the rear exhaust pipe82. A seat86is arranged in the rear of the fuel tank25.

FIG. 2is a side view showing a body frame of a two-wheeled vehicle according to the present invention. The body frame11is composed of a head pipe12, a pair of left and right main pipes92,92(only reference numeral92on this side is shown) for obliquely extending so as to extend rearwardly and backward from the head pipe12and further obliquely extending backward toward the lower part Front pipes93,93(only reference numeral93on this side is shown) are laid over to the main pipes92,92from the lower part of the head pipe12with a pair of left and right down tubes94,94(only reference numeral94on this side is shown) extending substantially toward the lower part from the front pipes93,93. Lower pipes96,96(only reference numeral96on this side is shown) are provided for extending so as to curve rearwardly from the lower ends of these down tubes94,94. Seat rails98,98(only reference numeral98on this side is shown) extend rearwardly from the upper part of the rear part of the main pipes92,92. Sub-pipes101,101(only reference numeral101on this side is shown) are provided for connecting to respective intermediate parts of the seat rails98,98and the rear end portions of the main pipes92,92, the lower ends of which are connected to the lower pipes96,96.

Reinforcement pipes105,105(only reference numeral105on this side is shown),106,106(only reference numeral106on this side is shown) are provided between the front pipes93,93, the down tubes94,94and the head pipe12. A first cross pipe107is mounted between the down tubes94,94in order to install a front engine hanger43. A second cross pipe108is mounted between the main pipes92,92in order to install a rear upper engine hanger44. A third cross pipe111is mounted between the sub-pipes101,101in order to install a rear lower engine hanger46. Pivot plates112,112(only reference numeral112on this side is shown) are installed to connected portions between the main pipes92,92and the sub-pipes101,101in order to install a swing shaft (that is, a pivot shaft) of a swing arm21(SeeFIG. 1). Shock absorber installation plates113,113(only reference numeral113on this side is shown) are installed to connected portions between the seat rails98,98and the sub-pipes101,101in order to install each upper end of the rear shock absorber units23,24(SeeFIG. 1).

Front installation areas48for installing the fuel tank25to the body frame11are installed to the main pipe92and the front pipe93, and are provided on the left and right of these main pipe92and front pipe93.

Rear installation areas51for installing the rear part of the fuel tank25to the body frame11are installed on the respective insides of the seat rails98,98.

FIG. 3is a side view showing a principal part of the front part of a two-wheeled vehicle according to the present invention wherein in order to support the front engine hanger43, in the front part of the first cross pipe107mounted between the down tubes94,94(only reference numeral94on this side is shown), there are provided circular-arc-shaped concave portions107a,107a(only reference numeral107aon this side is shown). Within the circular-arc-shaped concave portions107a,107a, in the front part of the exhaust pipes35to38(exhaust pipes35,38are not shown), the radiator77is arranged through a part of the exhaust pipes36.,37(in this case, only the exhaust pipes36,37connected to two cylinders on the inside are shown, of the front cylinders of the engine18) for extending so as to curve downwardly from the front part of the engine18. A radiator cap116is mounted on the radiator77. An upper installation stay117is provided for installing the upper part of the radiator77to the reinforcement pipe106. A lower installation stay118is provided for installing the lower part of the radiator77to the down tube94.

FIG. 4is a view taken along an arrow4ofFIG. 3with the exhaust pipes35to38being illustrated in cross-sectional views. The arrow (FRONT) in the figure indicates the front part of the vehicle (and so forth).

A first cross pipe107is provided for constituting the body frame11and is a member in which circular-arc-shaped concave portions107a,107ahave been formed at the left and right in the front part. Within these circular-arc-shaped concave portions107a,107a, exhaust pipes36,37have been arranged in proximity to each other. Further, a substantially circular-arc shaped radiator77, the central part of which is convex toward the rear part of the vehicle, has been arranged in proximity to the exhaust pipes36,37. A left hanger43aand a right hanger43bare provided which constitute a front engine hanger43, and are composed of two members, respectively.

As described above, the first cross pipe107is provided with circular-arc-shaped concave portions107a,107a. One portion each of the exhaust pipes36,37is arranged within the circular-arc-shaped concave portions107a,107awith the exhaust pipes36,37being arranged further in the rear. The radiator77is also arranged in the rear in closer proximity to the exhaust pipes36,37. This is because in the space between a locus121(locus is the place when the front wheel14is moved by the handlebars16(SeeFIG. 1) and a side of the front wheel14comes extremely close to the radiator77) of the outer periphery of the front wheel14(SeeFIG. 3) indicated by an imaginary line in theFIG. 4, and the first cross pipe107a thickness T of the radiator77is made as large as possible. Thus, the capacity of the radiator77is increased to enhance the heat radiation effect. Also, in the present invention, the position of the lower end portion77aof the radiator77is arranged at substantially the same position as or lower than the first cross member107, whereby the height A of the radiator77has been made larger to increase the capacity of the radiator77.

Particularly, in a two-wheeled vehicle of a race specification in which the engine18(SeeFIG. 3) is continuing to be driven at high speed, since the output and durability of the engine18are greatly affected by the cooling performance of the radiator77, it becomes an indispensable condition to have a large-sized radiator77having a large capacity.

Reverting toFIG. 3, with respect to an axle123of the front wheel14and assuming a straight line which passes through a central point123a, which is the center of the axle123, and intersects a down tube94at right angles to be124, the first cross pipe107has been provided below this straight line124. The positional relationship between the straight line124at this time and the first cross pipe107is in a so-called “1G state” in which only a driver rides on a motorcycle10.

A distance D between the front wheel14and the down tube94becomes extremely small on the straight line124. The first cross member107is provided below the straight line124as described above, whereby since the first cross member107can be arranged apart from the position whereat the distance D between the front wheel14and the down tube94becomes extremely small, a distance between the front wheel14and the exhaust pipe36,37can be easily secured. For example, in a case where the first cross member107is provided above the straight line124, the distance D becomes small when the front wheel14strokes on the handlebars16side.

FIG. 5is a side view showing a fuel tank for a two-wheeled vehicle according to the present invention. The fuel tank25includes a rear part of the bottom wall25awherein a fuel pump127is installed and arranged within the fuel tank25. On the inside of the front part, there are provided a pair of left and right engaging members128,128for engaging with a front part installation area48(SeeFIG. 2) on the body frame11(SeeFIG. 2) side. In the lower part of the rear part, there is provided a tank rear part side installation area131to be installed to a rear part installation area51(SeeFIG. 2) on the body frame11side. In addition, an oil feeding port133is provided.

FIG. 6is a perspective view showing the structure for installing a front part of a fuel tank for a two-wheeled vehicle according to the present invention. The front part installation area48on the body frame11side is composed of left and right installation areas135,135. The installation area135is composed of a U-shaped plate136installed to the main pipe92and the front pipe93, a supporting pin137is provided for extending from the U-shaped plate136sideways of the vehicle, and a shock absorbing rubber138is provided for being fitted in this supporting pin137.

The engaging member128on the fuel tank25(SeeFIG. 5) side includes two members, a base member141made of aluminum alloy welded to a side wall25bof the fuel tank25, and an engaging body143installed to the base member141with bolts142. . . ( . . . represents a plurality, and so forth). A first concave portion145is provided at the base member141. A second concave portion146is provided at the engaging body143. The first concave portion145and second concave portion146are portions for constituting an engaging concave portion147.

FIG. 7is a cross-sectional view taken on line7-7ofFIG. 5, and illustrating that on the inside of the fuel tank25, there is formed a concave inner wall25ccomposed of left and right side walls25b,25band a bottom wall25afor connecting upper ends of these side walls25b,25b. A base member141of the engaging member128is welded to the side wall25b. The engaging body143is installed to this base member141with bolts142. . . . The engaging member128is caused to engage with an installation area135of the front part installation area48on the body frame11(SeeFIG. 2) side, that is, the engaging member128is supported by the supporting pin137and the U-shaped plate136via the shock absorbing rubber138.

FIG. 8is an exploded perspective view showing the structure and assembly procedure of a fuel tank engaging member for a two-wheeled vehicle according to the present invention.

The base member141of the engaging member128is composed of a flat portion151, the edge of which is welded to the side wall25bof the fuel tank25(SeeFIG. 7) and a U-shaped stand-up wall152for standing up from the flat portion151. First female threads153,153are provided on each end portion of the U-shaped stand-up wall152with pillar-shaped portions154,154for standing up from the flat portion151, integrally molded to the U-shaped stand-up wall152. Second female threads156,156are provided on the pillar-shaped portions154,154. The base member141is a member wherein on the inside of the U-shaped stand-up wall152, there has been formed the first concave portion145.

The engaging body143is composed of an U-shaped flat portion161with a U-shaped stand-up wall162for standing up from this U-shaped flat portion161. First bolt insertion holes163,163are provided at each end portion of the U-shaped stand-up wall162with pillar-shaped portions164,164for standing up from the U-shaped flat portion161, integrally molded with the U-shaped stand-up wall162. Second bolt insertion holes166,166are provided on these pillar-shaped portions164,164. The engaging body143is a member wherein on the inside of the U-shaped stand-up wall162, there is formed the second concave portion146.

Hereinafter, the description will be made of the procedure of installing the engaging member128to the fuel tank25in order.

Positioning and tack fixing are performed on the side wall25bof the fuel tank25through the use of a welding jig in such a manner that an aperture145aof the first concave portion145of the base member141faces ahead, and four sides of the flat portion151of the base member141are continuously welded to the side wall25bof the fuel tank. A side151aof the flat portion151on the rear side is made shorter than a side151bon the front side, whereby the welding operation can be further facilitated.

An aperture146aof the second concave portion146of the engaging body143is caused to face ahead, and bolts142. . . are caused to pass through the first bolt insertion holes163,163and the second bolt insertion holes166,166of the engaging body143, respectively, to be screwed into the first female threads153,153and the second female threads156,156of the base member141. Installation of the engaging member128to the fuel tank25is completed.

Conventionally, the engaging member has been integrally formed, but in the present invention, the engaging member128is composed of two members the base member141and the engaging body143. Thus, when the engaging member128is welded, since the dimension, particularly the height H (SeeFIG. 7) of the base member141is small, a welding operation of the base member141within the concave inner wall25ccan be easily performed, and a welding jig or a welder can be easily inserted into the concave inner wall25c.

FIG. 9is a cross-sectional view of principal part showing a structure for installing a rear part of a fuel tank for a two-wheeled vehicle according to the present invention, and illustrating that at the end portion of the fuel pump127, a supporting plate171for supporting the fuel pump127is installed with bolts172. . . . In the rear part of the bottom wall25aof the fuel tank25, a pump installation member173is made of an aluminum alloy for installing the fuel pump127and is welded thereto. To the pump installation member173, the supporting plate171is installed with bolts174. . . . In the rear of the pump installation member173, the tank installation stay176for installing the fuel tank25to the body frame11(to be precise, a rear part installation portion51provided at the seat rails98,98(one seat rail is not shown)) is installed with bolts177. . . .

The supporting plate171is a part obtained by integrally molding pillar portions171a. . . to be installed to a pump-side plate181provided on the fuel pump127side, and is installed to the pump installation member173via an O-ring182.

A tank-side rear part installation area183is provided in the rear part of the fuel tank25for installation to the body frame11and is composed of the above-described tank installation stay176and a pump installation member173for supporting this tank installation stay176.

The rear part installation area51on the body frame11side is composed of a tank rear part supporting plate185, the cross section of which is substantially a crank-shape, mounted between the left and right seat rails98,98. A nut186is welded to this tank rear part supporting plate185with a cushion rubber187fitted in a frame-side installation hole (not shown) provided on the tank installation stay176. A washer191is inserted between this cushion rubber187and the tank rear part supporting plate185, respectively. A flanged collar192is provided through which the cushion rubber187has been inserted from above the cushion rubber187. A fitting bolt193is provided for penetrating the flanged collar192with the washer191and the tank rear part supporting plate185is screwed into the nut186. In this respect, for any other parts other than the tank rear part supporting plate185of the rear part installation area51, a pair is provided to the left and right respectively.

FIG. 10is a bottom view showing structure of a fuel tank rear part installation area for a two-wheeled vehicle according to the present invention. On a frame-shaped pump installation member173, there are formed stay installation areas196. . . for projecting outward. The stay installation areas196. . . are formed with female threads197, respectively. In a substantially U-shaped tank installation stay176, bored bolt insertion holes198. . . are provided together with frame-side installation holes201,201. Each bolt insertion hole198of the tank installation stay176is matched with each female thread197of the pump installation member173and the bolts177(SeeFIG. 9) are passed through, respectively, whereby the tank installation stay176is installed to the pump installation member173.

In the tank installation stay176, forward projecting portions203,203are provided at left and right end portions thereof, and at the tip portions of these forward projecting portions203,203, bolt insertion holes198are provided, respectively. Thus, the bolt insertion holes198are caused not to be in line with bolt insertion holes198at three other places, and the tank installation stay176is firmly combined with the pump installation member173to restrain the tank installation stay176from deflecting.

The frame-side installation holes201,201are circular holes bored in rearwardly projecting portions204,204respectively for projecting rearwardly from the tank installation stay176.

In this case, a plate installation area211is provided for installing the supporting plate171(SeeFIG. 9) on the fuel pump127(SeeFIG. 9) side to the pump installation member173. Female threads212. . . are formed on the plate installation area211. An O-ring groove213is provided for mounting the O-ring182(SeeFIG. 9).

Next, an installation procedure for the above-described fuel pump and fuel tank will be explained.

FIGS. 11(a) and11(b) are first working views showing the installation procedure for the fuel pump and the fuel tank according to the present invention.

InFIG. 11(a), the fuel pump127mounted with the supporting plate171(portion indicated by a thick line) is inserted into the fuel tank25through an aperture25dprovided on the bottom wall25aof the fuel tank25and an aperture173aof the pump installation member173as shown by the arrow. Thus, the supporting plate171is installed on the pump installation member173with a bolt (not shown).

FIGS. 12(a) and12(b) are second working views showing the installation procedure for the fuel pump and the fuel tank according to the present invention.

InFIG. 12(a), an engaging member128of the fuel tank25is caused to engage with the front part installation part48of the body frame11.

InFIG. 12(b), the cushion rubber187is fitted into the frame-side installation hole201of the tank installation stay176. The washer191engages with the underside of the cushion rubber187with the flanged collar192being inserted into the cushion rubber187. The fitting bolt193is caused to penetrate the flanged collar192, the washer191and the tank rear part supporting plate185and is screwed into a nut186. Thereby, the installation of the fuel tank25to the body frame11is completed.

As explained inFIGS. 1,5and9, according to the present invention, there is firstly provided a motorcycle10as a two-wheeled vehicle in which the fuel tank25is installed to the body frame11. Within this fuel tank25, there is provided the fuel pump127, wherein the fuel tank25is installed to the body frame11via the pump installation member173. To the pump installation member173, there is installed the tank installation stay176for fixing the fuel tank25to the body frame11.

Since the fuel pump127is installed to the fuel tank25via the pump installation member173and to the pump installation member173, the tank installation stay176has been installed, as compared with, for example, a case where the fuel pump is directly installed to the bottom wall of the fuel tank, the stiffness of the fuel pump installation area can be enhanced by the pump installation member173, and by installing the tank installation stay176to such a fuel pump installation area with enhanced stiffness. Thus, the stiffness of the fuel pump installation area can be further enhanced and the stiffness of the installation area of the tank installation stay176to the fuel tank25side can be also enhanced as compared with a case where the tank installation stay176is directly installed to the bottom wall of the fuel tank. Therefore, the fuel pump127can be further reliably supported, the tank installation stay176becomes firmer, and sound vibration performance of the vehicle can be improved.

As explained inFIGS. 5 to 9, according to the present invention, there is provided a structure for installing a body frame for a motorcycle10in which on the side walls25b,25bas left and right inner walls caused by depressing the center of the underside of the fuel tank25upwardly over the front and the rear, concave-shaped engaging members128are installed, respectively. The fuel tank25is installed to the body frame11by engaging installation areas135,135as left and right convex portions provided on the body frame11with these engaging members128, respectively. The engaging member128is constructed of two members, a base member141welded to the fuel tank25and an engaging body143for fastening to this base member141by means of bolts142. . . as fastening means.

Since the engaging member128is constructed of two members, a base member141welded to the fuel tank25and an engaging body143for fastening to this base member141with bolts142. . . , it is possible to reduce a size, particularly the height H of the base member141of the present invention smaller than the conventional engaging member. In the case of installing the base member141to the fuel tank25by welding, it is easy to insert a welding jig or a welder for positioning or fixing the base member141on side walls25b,25bas left and right inner walls inside the fuel tank25without interfering with the left and right side walls25b,25b.

Accordingly, the workability of the base member141during welding can be enhanced, and the capacity of the fuel tank25can be secured, or the fuel tank25can be prevented from becoming large-sized. Further, since the base member141can be made to be small-sized, the same engaging member128can be installed to fuel tanks for different types of two-wheeled vehicles, and the general-purpose properties can be enhanced. When changing a shape of the engaging member128depending upon the vehicle type, it is possible to change only one of the base member141and the engaging body143, to apply the other, and to restrain the cost from increasing.

The present invention is secondly characterized in that an axis47of the cylinder of the engine18arranged below the fuel tank25is caused to extend upwardly with air intake system parts such as a carburetor41and an air cleaner42for extending toward the rear being installed in the rear of the cylinder. The pump installation member173and the tank installation stay176have been arranged substantially above the air intake system parts.

The engine18in which the axis47of the cylinder has been caused to extend upwardly is shaped such that the front part of the bottom wall25aof the fuel tank25is depressed upwardly and the rear part of the bottom wall25aof the fuel tank25bulges downwardly. In an engine in which the fuel pump127has been arranged within the fuel tank25, the fuel pump127is to be installed in the rear part of the bottom wall25aat the lowest position of portions of the fuel tank25. Further, if the air intake system parts extend toward the rear from the engine18, the rear part of the bottom wall25aof the fuel tank25which is located above the air intake system parts will become substantially flat. Thus, the pump installation member173will become substantially flush with the tank installation stay176so that it becomes possible to be combined by making them to come in close proximity to each other. If the pump installation member173comes in close proximity to the tank installation stay176, it will be possible to shorten the tank installation stay176and to firmly install the fuel tank25to the body frame11side. Also, the weight of the tank installation stay176will be able to be saved.

The present invention includes an engaging concave portion147that is a concave portion to be provided on the engaging member128that is constructed of a first concave portion145provided on the base member141and a second concave portion146provided on the engaging body143.

Since the engaging concave portion147of the engaging member128is constructed of a first concave portion145of the base member141and a second concave portion146of the engaging body143, it is possible to prevent the second concave portion146from becoming large-sized, that is, the engaging body143from becoming large-sized in the present invention as compared with, for example, an engaging member, the engaging concave portion of which is constructed of only the second concave portion.

In the present invention the tank-side rear part installation area183is provided in the rear of the fuel tank25that has been constructed such that the tank installation stay176for integrally extending from the pump installation member173for installing, to the fuel tank25, the fuel pump127arranged within the fuel tank25is installed to the body frame11.

Since the tank-side rear part installation area183in the rear of the fuel tank25has been constructed such that the tank installation stay176for integrally extending from the pump installation member173is installed to the body frame11, the strength/stiffness of the tank-side rear part installation area183can be enhanced by the pump installation member173and the tank installation stay176without increasing a number of parts of the tank-side rear part installation area183of the fuel tank25as compared with the conventional case even if the engaging member128in the front part of the fuel tank25is made into a two-part divided structure. This becomes preferable as the structure for installing the fuel tank.

FIG. 13is a cross-sectional view showing engine supporting structure for a two-wheeled vehicle according to the present invention illustrating the structure for supporting the engine18with a rear upper engine hanger44.

The rear upper engine hanger44is composed of a left hanger221and a right hanger222which have been caused to project forward from the left and right of the second cross pipe108, respectively.

The left hanger221is composed of a left extending member224having a U-shape in cross section obtained by press-forming a plate, and a cylindrical member225installed to the tip of this extending member224.

The cylindrical member225is obtained by pressing a first flanged collar227made of metal and a second flanged collar228made of metal in from the end portion respectively. The first flanged collar227and the second flanged collar228are members in which a bolt insertion hole227a,228ahas been bored, respectively.

The right hanger222is composed of a base member231having a L-shape in cross section obtained by press-forming a plate and a right extending member234coupled by a nut232and a bolt233installed to this base member231.

The right extending member234is a member at the tip portion of which a through-hole234ahas been bored and is obtained by pressing a pipe bushing236into this through-hole234a.

The pipe bushing236is composed of an outer cylinder237, an inner cylinder238arranged on the inside of this outer cylinder237and shock absorbing rubber241adhered by vulcanization between these outer cylinder237and inner cylinder238.

A body-side left installation area245and a body-side right installation area246are provide and project upwardly toward the rear from the rear part of the crankcase31of the engine18, respectively. The body-side left installation area245and body-side right installation area246include bored bolt insertion holes245a,246a, respectively. Within the bolt insertion hole227aof the first flanged collar227, the bolt insertion hole228aof the second flanged collar228, the bolt insertion holes245a,246aand the inner cylinder238of the pipe bushing236, a hollow supporting bolt248is passed through. Into the tip of the supporting bolt248, a supporting nut251is screwed. Thus, the upper part of the rear part of the engine18is supported by the rear upper engine hanger44. In this respect, the washer253is interposed between the body-side right installation area246and the inner cylinder238of the pipe bushing236.

The engine18is, as shown inFIG. 1, supported by the front engine hanger43, the rear upper engine hanger44and the rear lower engine hanger46.

Since the front engine hanger43and the rear lower engine hanger46support the engine18via the collar made of metal as in the case of the above-described left hanger221the combination with the engine18becomes firmer. As described above, of the three engine hangers43,44,46, the rear upper engine hanger44and particularly the right hanger222is elastically supported via the pipe bushing236. This is because the stiffness of the body frame11to which the engine18has been added is adjusted by changing the setting of the hardness of rubber. In other words, as compared with a case where all places of the engine hangers are combined in a so-called rigid way via collars made of metal, the body frame11has been slightly provided with flexibility in the present invention.

Another reason why the engine18has been elastically supported by the right hanger222is that it is easier to maintain than other engine hangers43,46and the left hanger221.

If the supporting nut251is loosened to be removed from the supporting bolt248, and the bolt233of the right hanger222is loosened to remove the right extending member234from the base member231, the pipe bushing236will be able to be easily attached or detached to or from the right extending member234.

Also, as regards the supporting bolt248, the weight thereof has been saved by making it hollow.

Next, the description will be made of the procedure for installing the engine18to the above-described rear upper engine hanger44.

FIGS. 14(a) to14(d) are working views illustrating the procedure for installing the engine to a rear upper engine hanger for a two-wheeled vehicle according to the present invention.

InFIG. 14(a), the pipe bushing236is pressed into a through-hole234ain the right extending member234, and the washer253is touched to the side of the pipe bushing236.

InFIG. 14(b), the first flanged collar227and the second flanged collar228are pressed into the inner surface of the cylindrical member225of the left hanger221.

InFIG. 14(c), between the left hanger221and the right hanger222, there are arranged the body-side left installation area245and the body-side right installation area246of the engine18. The supporting bolt248is caused to pass through the bolt insertion hole227ain the first flanged collar227, the bolt insertion hole228ain the second flanged collar228, the bolt insertion hole245ain the body-side left installation area245, the bolt insertion hole246ain the body-side right installation area246and the inner cylinder238of the pipe bushing236.

InFIG. 14(d), the supporting nut251is screwed into the tip of the supporting bolt248. Thereby, installation of the engine18to the rear upper engine hanger44is completed.

In the embodiment of the present invention, the tank installation stay has been installed to the pump installation member with bolts, but the present invention is not limited thereto. The tank installation stay may be installed to the pump installation member by welding and the pump installation member and the tank installation stay may be made into an integrally-molded article made of an aluminum alloy.

The body frame structure according to the present invention is suitable for a two-wheeled vehicle in which the fuel pump has been built in the fuel tank and the fuel pump has been arranged in the rear within the fuel tank.