JP2002326592A - Motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a fuel tank stored in a down frame. SOLUTION: A down frame 14 extending from a head pipe 12 in lower rear side is formed in a closed section. The rear end part of the down frame 14 is opened downward. The fuel tank 11 is stored in the down frame 14 by using the opening as an access port for the fuel tank 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle having a fuel tank accommodated in a down frame of a vehicle body frame.

[0002]

2. Description of the Related Art A conventional motorcycle of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 2000-280962. The motorcycle body frame disclosed in this publication has a head pipe, a down frame extending rearward and downward from the head pipe, and a seat frame extending upward from the rear end of the down frame and integrally formed by casting. ing. Casting is performed using a mold that separates vertically. Therefore, the down frame is
The convex portion of the lower mold faces downward from the concave portion of the cavity of the upper mold to form an inverted U-shaped cross section that is opened downward. In this motorcycle, the fuel tank is housed inside the down frame formed as described above.

[0003]

However, in the conventional motorcycle constructed as described above, the fuel tank has to be formed, for example, to have a large thickness so as to increase the strength, and there is a problem that the weight becomes heavy. there were. This is because the fuel tank is exposed downward from the lower end opening of the down frame. That is, the fuel tank is formed so that foreign matter such as pebbles that are flipped up by the front wheel does not deform when the foreign matter hits the fuel tank from below.

The present invention has been made to solve such a problem, and has as its object to reduce the weight of a fuel tank housed in a down frame.

[0005]

In order to achieve this object, a motorcycle according to the present invention has a down frame extending rearward and downward from a head pipe in a closed cross-sectional shape, and a rear end of the down frame. The fuel tank is housed in a down frame by opening the fuel tank downward, and the opening is used as an access port for the fuel tank.

According to the present invention, since the periphery of the fuel tank is covered by the down frame and no external force is applied to the fuel tank, the fuel tank can be formed to have relatively low strength.

A motorcycle according to a second aspect of the present invention is the motorcycle according to the first aspect of the present invention, wherein a cylindrical member projects upward from a front end of a fuel tank. The member is inserted into and fixed to the mounting hole for the tubular member of the down frame, and the rear end of the fuel tank is supported by a bracket which is laid across the rear end opening of the down frame.

According to the present invention, the front portion of the fuel tank can be attached to the down frame using the tubular member of the fuel tank. Further, the rear end of the down frame can be reinforced by a bracket supporting the rear end of the fuel tank.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a motorcycle according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view of a motorcycle according to the present invention, FIG. 2 is an enlarged side view showing an engine mounted portion, and FIG. 3 is a side view showing a portion supporting a rear end portion of a fuel tank. It is drawn with the part broken. 4 is a plan view of a cross member for supporting the front part of the engine, FIG. 5 is a cross-sectional view taken along line V-V of the body frame and part of the engine in FIG. 2, and FIG. -VI line sectional view,
7 is a cross-sectional view of the vehicle body frame taken along line VII-VII in FIG.
FIG. 8 is a cross-sectional view of the head pipe, and FIG. 9 is an enlarged cross-sectional view showing a front support portion of the fuel tank. 10 and 11 are views showing another example of forming the head pipe. FIG. 12 is a cross-sectional view taken along line XX in FIG. 3, and FIG. 13 is a cross-sectional view of a damper rubber for a fuel tank.

In these figures, the reference numeral 1 denotes a motorcycle according to this embodiment. Reference numeral 2 denotes a body frame, 3 denotes an engine, 4 denotes a front wheel, 5 denotes a front fork, 6 denotes a steering wheel, 7 denotes a rear wheel, 8 denotes a rear arm, 9 denotes a cushion unit, 10 denotes a seat, 1
Reference numeral 1 denotes a fuel tank.

The front fork 5 is of a telescopic type and is rotatably supported by a head pipe 12 of a body frame 2 described later. The rear arm 8 includes a left arm 8a and a right arm 8 on both sides of the rear wheel 7.
b (see FIG. 6), and the pivot shaft 1
3 (see FIGS. 2 and 6) so as to be rotatable. The cushion unit 9 is interposed between the middle of each of the arms 8 a and 8 b of the rear arm 8 and the body frame 2.

As shown in FIG. 1, the body frame 2 includes the head pipe 12, a down frame 14 extending downward from the head pipe 12, and a seat frame extending upward from the rear end of the down frame 14. 15 and a rear frame 16 (see FIGS. 2 and 3) extending downward from the rear end of the down frame 14 are integrally formed. More specifically, as shown in FIGS. 5, 7 and 8, the vehicle body frame 2 is formed by joining a left body half 21 and a vehicle right half 22 by friction stir welding. ing.

The two halves 21 and 22 are formed by casting, respectively, and the left half 21 of the vehicle body has a cross-sectional shape opened toward the right side of the vehicle body. It has a cross-sectional shape that is open toward the left side of the vehicle body. That is, a mold (not shown) for molding these two halves 21 and 22 has a cavity formed by a concave portion and a convex portion, and a female mold having a concave portion and a male mold having a convex portion. Uses a structure that comes and goes in the vehicle width direction.

As shown in FIGS. 5, 7 and 8, the left half 21 of the vehicle body has a ridge 21a formed on the inner edge of the vehicle body, and the right half 22 of the vehicle body has an inner edge. A groove 21b into which the ridge 21a fits is formed on the edge. In order to join these two halves 21 and 22 to each other, the concave groove 21b and the ridge 21a are fitted and overlap each other in the thickness direction, and in this state, a rotary tool for friction stir welding is brought into contact with the outer surface. By doing it. After joining, the hole 12a (see FIG. 8) in the head pipe 12 is honed by machining to adjust the head pipe 12 to a predetermined size. In this embodiment, the edge portion of the right half portion 22 of the vehicle body forming the concave groove 21b is formed so as to be thicker than other portions. This is to prevent the joint from being deformed by buckling due to being pressed by the rotating tool when performing friction stir welding.

The head pipe 12 can be formed as shown in FIGS. 10 and 11 in addition to the above-described one. 10 and 11 show another example of forming the head pipe. FIG. 10 (a) is a plan view and FIG.
(B) is a longitudinal sectional view. In the head pipe shown in FIG. 10, rings 12b for press-fitting bearings are fixed to the upper and lower openings. The ring 12b can be fixed to the head pipe 12 by a friction stir welding method, brazing, welding, or the like.

After the ring 12b is fixed to the head pipe 12, the inner peripheral portion thereof is finished by honing or the like. The position and shape of the inner peripheral surface of the ring 12b before the post-processing is shown by a two-dot chain line in FIG. By press-fitting a bearing for supporting the steering shaft into the ring 12b, it is possible to prevent a load at the time of press-fitting from being applied to the head pipe 12. Therefore, the steering shaft (not shown) can be firmly supported while employing a structure in which the head pipe 12 is formed by the left and right halves 21 and 22. In FIG. 10B, what is indicated by reference numeral 12c facing the inside of the head pipe 12 is an inner flange for positioning the ring 12b in the axial direction. The inner flange 12c is provided on both left and right halves 21,22.
Are formed integrally with each other. The head pipe 12 shown in FIG. 11 is formed separately from the left and right halves 21, 22.
Welded to both halves. The weld is indicated by reference numeral 12d.

By joining the left half 21 of the vehicle body and the right half 22 of the vehicle body in this manner, a hollow portion 23 is formed inside the vehicle body frame 2. In the vehicle body frame 2, a portion other than the middle portion 24 in the front-rear direction corresponding to the front portion of the engine 3 is formed in a closed cross-sectional shape.
Auxiliary devices such as the fuel tank 11 and the carburetor 25 are inserted and mounted in the device 3.

As shown in FIG. 5, the intermediate portion 24 is formed in a U-shaped cross section and is opened downward, and a cross member 26 is provided at a lower end opening 24a with the left half 21 of the vehicle body and the vehicle body. It hangs over the right half 22 and is laid horizontally. As shown in FIGS. 2, 4 and 5, a front bracket 27 for supporting the front part of the engine is attached to both ends of the cross member 26 in the vehicle width direction by bolts 28 for attaching the cross member.

The mounting bolt 28 is screwed from below into the mounting seat 29 of the left and right halves 21 and 22 so as to be easily detached from the lower end opening. A coil 31 is mounted on the upper surface of the right side (the left side in FIG. 5) of the cross member 26 via a coil bracket 30. This coil 31 is for supplying power to the ignition plug P of the engine 3.

In FIG. 5, the reference numeral 32 provided above the cross member 26 is a bracket for supporting the rear end of the fuel tank 11. This bracket 32 is formed in a gate shape that is opened downward,
Both ends are fixed to the left and right halves 21 and 22 of the body frame 2 by fixing bolts 33. That is, the bracket 32 is laid horizontally on the opening at the rear end of the down frame 14. The fixing bolt 33 is screwed into the mounting seat 34 of each of the two halves 21 and 22 from the inside of the vehicle body.

In this embodiment, of the left and right fixing bolts 33, the fixing bolts 33 on the left side of the vehicle body are used.
The fuel cock support bracket 35 and the fuel tank support bracket 32 are fastened together to the left half 21 of the vehicle body. The fuel cock attached to the fuel cock supporting bracket 35 is indicated by reference numeral 36 in FIG.

The fuel tank 11 is formed by a blow molding method or a rotational molding method using a synthetic resin as a material. The fuel tank supporting bracket 32 supports the rear end of the fuel tank 11 and the front end of the fuel tank 11 is supported by the down frame 14 Have been supported. The rear end of the fuel tank is supported by attaching a grommet 37 to the bracket 32 and fitting a support projection 38 projecting downward from the rear end of the fuel tank into a support hole 37a of the grommet 37 from above. Is going.

As shown in FIG. 9, the front end of the fuel tank is supported by screwing a fixing nut 40 to a cylindrical member 39 integrally projecting from the fuel tank 11 by insert molding. And flange 3 at the base of the tubular member
9a by sandwiching the supporting cylinder 42 of the vehicle body frame 2 via the sealing member 41. The inner peripheral portion 42a of the supporting cylinder 42 forms a mounting hole for a tubular member according to the present invention. In FIG. 9, reference numeral 43 denotes a fueling cap.

In this embodiment, in order to prevent the upper surface of the fuel tank 11 from coming into contact with the inner surface of the down frame 14 with the fuel tank 11 housed in the down frame 14, as shown in FIG. Rubber 44 is attached to the down frame 14. This damper rubber 44
Is fitted and fixed in a concave portion 45 formed in a joint portion of the left and right half portions 21 and 22 of the down frame 14. The concave portion 45 is formed by bending the ridges 21a and 22a projecting from a joint portion between the left half portion 21 and the right half portion 22 of the vehicle body into a semicircular shape as shown in FIG.

The engine 3 of the motorcycle 1 is a four-cycle air-cooled single-cylinder engine. As shown in FIG. 2, a cylinder 3a is disposed so that its axis is directed in the front-rear direction of the vehicle body, and is provided on a crankcase 3b. 3 mounting bosses 5
1 to 53 are mounted on the vehicle body frame 2 by mounting bolts 54 to 56, respectively. The power of the engine 3 is transmitted from the output sprocket 57 provided at the left end of the vehicle body of the crankcase 3b to the rear wheel 7 via a chain (not shown). In this embodiment, the engine 3 is covered with an engine cover 58 in a state where the engine 3 is mounted on the vehicle body frame 2 as shown in FIG.

An intake pipe 61 is provided above the cylinder 3a.
The carburetor 25 is connected via a, and an exhaust pipe 62 is connected to the lower part of the cylinder 3a. The intake pipe 61 is formed so as to be inclined so as to be gradually eccentric to the rear of the vehicle body as it goes upward, and extends above the cross member 26 from the lower end opening portion of the halfway portion 24 of the vehicle body frame 2. I have. The carburetor 25 connected to the rear end of the intake pipe 61 is disposed behind the cross member 26 and connects to an intake duct 64 of an air cleaner 63 provided on the vehicle body frame 2.

Of the three bosses 51 to 53 for attaching the engine 3 to the body frame 2, the front boss 51 at the front end of the crankcase is attached to the front bracket 27 for supporting the engine, which extends downward from the cross member 26. The upper boss 52 and the lower boss 53 at the rear end of the crankcase are mounted to the rear frame 16 of the vehicle body frame 2 via a rear bracket 65 for supporting the engine.

As shown in FIG. 6, a damper rubber 66 is interposed between the front boss 51 and the mounting bolt 54 and between the upper boss 52 and the mounting bolt 55. FIG. 6 shows a connecting portion between the upper boss 52 and the mounting bolt 55, but a connecting portion between the front boss 51 and the mounting bolt 54 has a structure equivalent to the structure shown in FIG. The other boss 53 is rigidly fixed to the rear bracket 65 via a mounting bolt 56. By interposing the damper rubber 66 at two of the three mounting portions in this manner, the vibration of the engine 3 transmitted to the vehicle body frame 2 can be reduced while the engine 3 is firmly supported. In addition to the structure of this embodiment, the engine 3 is mounted on the vehicle body frame 2 by fixing three bosses rigidly to the vehicle body frame 2 or by elastically supporting the upper boss 52 and the lower boss 53 on the front side. The boss 51 is rigidly fixed, the upper boss 51 is rigidly fixed by elastically supporting the front boss 51 and the lower boss 53, and the other boss is elastically supported by any one of the three bosses. Can be rigidly fixed, or all the bosses can be elastically supported, or can be appropriately changed.

As shown in FIG. 2, the rear bracket 65 for mounting the upper boss 52 and the lower boss 53 is formed in a plate shape, and two fixing bolts 67, 68 and the pivot shaft 13. The material forming the rear bracket 65 is steel,
Various materials such as an aluminum alloy, a magnesium alloy, and a fiber-reinforced plastic can be used. The rear frame 16 constitutes a part of the rear end of the down frame 14, and as shown in FIGS. 3 and 6, side walls 16a and 16b at both ends in the vehicle width direction, a front wall 16c, and a rear wall. Wall 1
6d and the bottom wall 16e are formed so as to be opened upward. Since the upper open portion of the rear frame 16 is closed by the down frame 14 of the vehicle body frame 2, the rear frame 16 has a closed cross-sectional shape as a result.

The rear frame 16 is integrally formed with cylindrical bosses 69 and 70 extending from one end to the other end in the vehicle width direction, and supports the pivot shaft 13 with the cylindrical bosses 69 and 70. are doing. The pivot shaft 13 has a flange 13a integrally formed on one end and a nut 71 screwed on the other end. The pivot shaft 13 is provided between the flange 13a and the rear frame 16, and between the nut 71 and the rear frame 16. The nut 71 is fastened to the rear frame 16 in a state where the rear bracket 65 is sandwiched between them. The left arm 8a and the right arm 8b of the rear arm 8 are rotatably supported at both ends of the pivot shaft 13.

In order to mount the engine 3 on the vehicle body frame 2, first, as shown in FIGS. 5 and 9, the fuel tank 11 is mounted on the down frame 14.
The fuel tank 11 is attached to the vehicle body frame 2 by attaching a support bracket 32 to the rear end of the fuel tank 11 in advance, and attaching the tubular member 39 at the front end of the fuel tank to the down frame front by the fastening structure. Fix it. Next, the bracket 32 is fixed to the down frame 14 together with the fuel cock 36 by the fixing bolt 33. A fuel hose (not shown) for connecting the fuel cock 36 and the fuel tank 11 is attached before the fuel tank 11 is inserted into the down frame 14.

Then, a nut 40 is screwed onto the cylindrical member 39, and the bracket 32 is fixed to the down frame 14 by fixing bolts 33. At this time, fuel cock 3
A bracket 35 having 6 is also attached. Fuel cock 36
Hose connecting the fuel tank 11 and the fuel tank 11 (not shown)
Is installed before the fuel tank 11 is inserted into the down frame 14.

In mounting the engine 3 on the vehicle body frame 2, first, the front bracket 27 is fixed to the front boss 51 at the front end of the crankcase by a mounting bolt 54, and the cross member 26 is temporarily assembled to the front bracket 27. . The engine 3 includes an intake pipe 61 and a carburetor 2.
5 is attached in advance. The connection between the carburetor 25 and the intake duct 64 is made by inserting a hand into the vehicle body frame 2 through an opening (not shown) on the seat frame 15 side after the engine is mounted.

Next, the front bracket 27, the cross member 26, the carburetor 25 and the like are inserted into the vehicle body frame 2 from the lower end opening portion of the halfway portion 24 of the vehicle body frame 2, and the upper boss 52 at the rear end of the engine is connected to the upper boss 52. The lower boss 53 and the rear bracket 65 are temporarily held by the mounting bolts 55 and 56. With the engine 3 temporarily held on the body frame 2 in this manner, the front bracket 27 and the cross member 26 are fixed to the down frame 14 by the mounting bolts 28. Then, the upper boss 52 and the lower boss 53 are fastened to the rear bracket 65 by the fixing bolts 55 and 56 with a regular tightening force.
The engine mounting operation is completed.

The motorcycle 1 configured as described above has:
A down frame 14 extending rearward and downward from the head pipe 12 is formed in a closed cross-sectional shape, and a rear end of the down frame 14 is opened downward, and the opening is used as an access port for the fuel tank 11.
Since the fuel tank 11 is housed inside, the periphery of the fuel tank 11 can be covered by the down frame 14. For this reason, since no external force is applied to the fuel tank 11, as shown in this embodiment, the fuel tank 11 can be formed of synthetic resin so as to have a relatively low strength.

The motorcycle 1 has a fuel tank 1
1, a cylindrical member 39 is projected upward from the front end portion of the fuel tank 11, and the cylindrical member 39 is inserted into and fixed to the supporting cylinder 42 of the down frame 14. 14 bracket 32 laid horizontally on the rear end opening
, The cylindrical member 39 of the fuel tank 11
The front part of the fuel tank can be attached to the down frame 14 by utilizing the above. Further, the rear end of the down frame 14 can be reinforced by the bracket 32 supporting the rear end of the fuel tank 11.

Further, the left half 21 of the vehicle body frame 2 and the right half 22 of the vehicle body can be joined by, for example, brazing in order to avoid sticking to the friction stir welding method. Any method may be used as long as it is a solid phase bonding, and may be any method that does not melt the frame. When brazing, both halves 2
Apply brazing material to the joint in a state where 1, 22 are combined,
The brazing material is melted and joined by a heating furnace.

[0038]

As described above, according to the present invention, the periphery of the fuel tank is covered by the down frame, and no external force is applied to the fuel tank. Can be formed. Therefore, even when the fuel tank is formed of, for example, a synthetic resin or formed of metal, the fuel tank can be formed to be thin, and the fuel tank can be reduced in weight.

According to the second aspect of the present invention, the front portion of the fuel tank can be attached to the down frame by using the tubular member of the fuel tank. Therefore, a member exclusively connecting the front portion of the fuel tank to the down frame. Is unnecessary. In addition, since the rear end of the down frame can be reinforced by the bracket supporting the rear end of the fuel tank, the support of the rear end of the fuel tank and the reinforcement of the down frame can be performed by the same member. .

Therefore, both the front support portion and the rear support portion of the fuel tank can be supported by members having a plurality of functions (the tubular member and the bracket), so that the number of parts can be reduced. Not only the weight can be reduced, but also the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle according to the present invention.

FIG. 2 is an enlarged side view showing an engine mounting portion.

FIG. 3 is a side view showing a portion supporting a rear end of a fuel tank.

FIG. 4 is a plan view of an engine front support cross member.

FIG. 5 is a sectional view taken along line VV of a part of the vehicle body frame and the engine in FIG. 2;

6 is a sectional view taken along line VI-VI of a part of the vehicle body frame and the engine in FIG. 2;

7 is a sectional view of the vehicle body frame in FIG. 2 taken along line VII-VII.

FIG. 8 is a cross-sectional view of the head pipe.

FIG. 9 is an enlarged sectional view showing a front support portion of the fuel tank.

FIG. 10 is a view showing another example of forming a head pipe.

FIG. 11 is a sectional view showing another example of forming a head pipe portion.

FIG. 12 is a sectional view taken along line XX in FIG. 3;

FIG. 13 is a cross-sectional view of a damper rubber for a fuel tank.

[Explanation of symbols]

2 ... body frame, 11 ... fuel tank, 12 ... head pipe, 14 ... down frame, 21 ... left half of the body,
Reference numeral 22: right half of the vehicle body, 23: hollow portion, 32: bracket, 39: tubular member, 42: supporting cylinder.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yushi Inoue 2500 Shinkai, Iwata-shi, Shizuoka Yamaha Motor Co., Ltd. F-term (reference) 3D011 AF04 AF07 AG02 AH01 AK14 AK31 AL37

Claims (2)

[Claims] 1. A down frame extending rearward and downward from a head pipe is formed in a closed sectional shape, and a rear end of the down frame is opened downward, and the opening is used as an access port for a fuel tank in the down frame. A motorcycle characterized by containing a fuel tank in the motorcycle. 2. The motorcycle according to claim 1, wherein a cylindrical member is provided to project upward from a front end of the fuel tank, and the cylindrical member is inserted into a cylindrical member mounting hole of a down frame. A motorcycle, wherein the motorcycle is fixed, and a rear end of the fuel tank is supported by a bracket which is laid over a rear end opening of the down frame.