JP2903237B2 - Motorcycle body frame - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a body frame of a motorcycle, which simplifies the structure of a down tube and reduces the weight thereof, and employs welding from a head pipe to a down tube. By devising the joint structure of the connecting portion, the connecting strength can be remarkably improved.

[Conventional technology]

As a body frame of a motorcycle, generally, a head pipe extending rearward is connected to a head pipe by welding, and an upper end of a pair of right and left down tubes is connected to the head pipe by welding. In this general body frame, the connection between the head pipe and the main frame and the connection between the head pipe and the down tube are parts where the load is concentrated, and in motorcycles running on uneven terrain such as motocross. Since the impact applied to the vehicle body is even greater, the above concentrated load is particularly shocking and large. Measures have been taken, such as reinforcing the connecting portion with a reinforcing plate so that the connecting portion can withstand this shocking repetitive load.

On the other hand, in order to simplify the structure and reduce the weight of the body frame, there is a body frame in which one down tube is provided at the center of the body. In this case, the connection strength of the connection between the down tube and the head pipe is particularly problematic. In order to achieve the above, there is a head pipe in which a stay having an arcuate cross section is integrally formed, and the stay is welded to a state in which a tip portion of a down tube is supported (Japanese Patent Application Laid-Open No. 62-238180).

In the former prior art, since the two down tubes extend rearward, there is no problem in supporting the engine and the like, strength and rigidity of the vehicle body, and the like. On the other hand, in the latter conventional technique, since there is only one down tube, it is impossible to support the engine and the like, strength and rigidity of the vehicle body, and the like. From such a thing,
Regarding the latter conventional technology, in order to secure the stability of support of the engine and the like, and the strength and rigidity of the body frame, the down tube is branched into lower left and right lower tubes at the lower part, and the engine is supported by this lower down tube. In order to realize this structure, a connection between the tip of one upper down tube and the head pipe, and one upper down tube and two lower down tubes bifurcated. It is necessary to ensure the necessary connection strength and rigidity while making the connection structure of the connection portion as simple as possible, and the problem remains how to make the connection structure therefor.

[Problems to be solved by the invention]

The present invention relates to a configuration in which the down tube 1 is composed of one upper down tube and two lower down tubes bifurcated, the connecting portion between the head pipe and the tip of the upper down tube, and one upper down tube. The task is to devise the structure of both connecting parts so that the necessary connecting strength and rigidity can be secured while the connecting part between the tube, the lower end and the two lower down tubes is as simple as possible. It is.

[Means for solving the problem]

The measures taken to solve the above problems are the following elements (a)
(E).

(A) A head pipe and a frame member extending rearward and downward from the head pipe are integrally formed, and an integral member of the head pipe and the frame member is formed of an extruded material extruded in an axial direction of the head pipe. (B) The frame member of the head pipe has a pair of left and right plate-shaped portions suspended downward and downward, and a pair of ribs respectively connecting the plate-shaped portion and the head pipe. (C) an upper down tube is welded and connected to the head pipe and the frame member, and a reinforcing plate is welded from a lower side of the frame member to a lower side of the upper down tube. The connecting portion between the upper down tube and the frame member is reinforced, and (d) the connecting member has a U-shaped upper mounting portion. It has a pair of left and right lower mounting parts, the lower part of the upper down tube is welded to the end of the upper mounting part of the connecting member, and the lower part of the reinforcing plate is further welded to the front side of the upper mounting part, (E) The upper portions of the left and right lower down tubes are inserted into the left and right lower mounting portions of the connecting member, and the front and rear ends of the upper and lower tubes are connected to each other. The upper part of the pair of left and right lower down tubes is connected to the lower mounting part of the connecting member by being welded in combination with the lower mounting part of the connecting member.

[Action]

A head pipe and a frame member extending rearward and downward from the head pipe are integrally formed, and an integral member of the head pipe and the frame member is formed of an extruded material extruded in an axial direction of the head pipe. Since the frame member is composed of a pair of left and right plate-shaped portions hanging downward and rearward and a pair of ribs respectively connecting the plate-shaped portion and the head pipe, the strength and rigidity of the frame member are high, and High shear strength at the boundary between the head pipe and the frame member. Therefore,
The support strength of the frame member against an impact load from the down tube connected to the frame member is high.

An upper down tube is welded and connected to the head pipe and the frame member, and a reinforcing plate is welded from a lower side of the frame member to a lower side of the upper down tube. Since the connection portion with the member is reinforced, the connection strength of the connection portion between the head pipe and the upper down tube is high, and is reinforced only by one reinforcing plate. Simple.

Further, the connecting member has a U-shaped upper mounting portion and a pair of left and right lower mounting portions, a lower portion of the upper down tube is welded to an end of an upper mounting portion of the connecting member, and further, a front side of the upper mounting portion. Since the lower part of the reinforcing printer is welded to the lower part of the upper down tube is connected to the connecting member by this, the connecting member and the lower end of the upper down tube are firmly connected, and the reinforcing plate of this connecting part is Since the reinforcing plate for the connecting portion between the frame member and the distal end of the upper down tube is extended downward, the reinforcing structure using the reinforcing plate is simple, and the reinforcing effect of the reinforcing plate for both connecting portions is high.

Furthermore, the upper portions of the left and right lower down tubes are inserted into the left and right lower mounting portions of the connecting member, and the front and rear ends of the distal end thereof are combined with the lower mounting portion of the connecting member and welded. Thereby, since the upper parts of the pair of left and right lower down tubes are connected to the lower mounting part of the connecting member, the upper part of the lower down tube is firmly connected to the lower mounting part,
Further, since the forked portion is formed by an integral connecting member, the required strength and rigidity of the forked portion can be sufficiently secured.

As described above, the tip of one upper down tube is connected to the head pipe having the frame member, the lower end of the upper down tube is connected to the connecting member, and the lower mounting portion (bifurcated branch portion) on the left and right of the connecting member. A body frame having a structure in which the ends of the left and right lower down tubes are connected to each other to thereby connect a down tube having one upper down tube and left and right lower down tubes to a head pipe is formed. The connection strength and rigidity between the ends of the upper down tube are high, and the lower attachment parts (forked branch) on the left and right of the connection member are not welded structures but molded products, so their strength and rigidity are high, and furthermore, connection The connecting strength and rigidity of the connecting portion between the left and right lower mounting portions of the member and the left and right lower down tube tips are high. Since the reinforcing plate for the connecting portion between the head pipe and the upper down tube extends downward and also serves as the reinforcing plate for the connecting portion between the upper down tube and the connecting member, the reinforcing structure by the reinforcing plate is an extremely simple structure. It is.

〔Example〕

 Next, embodiments will be described with reference to the drawings.

The motorcycle according to the present embodiment is used for, for example, a motocross competition running on uneven terrain. A front pipe 2 constituting a body frame 1 has a front fork 3.
A front wheel 4 is provided at a lower end of the front fork 3. A front fender 5 is attached to the front fork 3, and the front fender 5 uses a fixed fender that is not linked to the vertical movement of the front wheel 4.

The head pipe 2 and a frame member 6 extending rearward and downward from the head pipe 2 are integrally formed. An integral member of the head pipe 2 and the frame member 6 is formed of an extruded material extruded in the head pipe axial direction. ing.

A pair of left and right substantially straight main frames 7 each having a substantially wide vertical cross section as viewed from the side are connected to the upper portion of the head pipe 2, and the rear of the main frame 7 is bent slightly downward. A pair of left and right rear arm brackets 8 are welded. This rear arm bracket 8
A rear arm pivot 9 is provided therebetween. A rear arm 10 is pivotally supported by the rear arm pivot 9, and a rear wheel 11 is supported at a rear portion of the rear arm 10.

As described above, the upper part of the head pipe 2 and the rear arm pivot 9 are connected by the pair of right and left substantially linear main frames 7 each having a vertical width and a rectangular cross section when viewed from the side, and the main frames 7 are formed of extruded material. A reinforcing plate 12 is welded to a lower front portion of the main frame 7.

The frame member 6 of the head pipe 2 is hung downward and rearward, and an upper down tube 13 is connected to the frame member 6 by welding, and the frame member 6 is shaped so as to smoothly connect to the upper down tube 13. From the lower side of the upper down tube 13 to the lower side of the frame member 6,
The reinforcing plate 14 is reinforced by welding.

The frame member 6 integral with the head pipe 2 is thicker as the thickness is closer to the head pipe 2, and has a shape corresponding to the stress distribution. Further, by forming the extruded member, the cross-sectional change of the frame member 6 can be freely set, and the frame member 6 can be smoothly connected to the upper down tube 13. Further, inside the pair of left and right frame members 6, a rib 6a for connecting the frame member 6 and the head pipe 2 is formed, and the rib 6a disperses stress and has a reinforcing effect by the rib itself. I have.

As described above, since the frame meva 6 to which the upper down tube 13 is connected is formed integrally with the head pipe 2, assembling accuracy is improved and the number of parts can be reduced.

Further, for example, in a motorcycle such as a motocross, the load in the direction of the head pipe increases, but since the integral part of the head pipe 2 and the frame member 6 is formed of an extruded material in the direction of the head pipe, the strength in the shear direction is improved. I do.

In addition, by welding the upper down tube 13 to the frame member 6, the number of welded portions is reduced, and even in the case of mass production, variation in strength due to welding conditions is reduced, and stable strength is obtained.

The upper down tube 13 is welded by abutting the front of the connection frame 15 on the upper side of the center thereof, and a reinforcing plate 16 is welded between the upper down tube 13 and the connection frame 15 above the connection portion, On the lower side of the connection portion, a reinforcing plate 17 is welded between the upper down tube 13 and the connection frame 15 and reinforced by these reinforcing plates 16 and 17.

The lower portion of the upper down tube 13 is connected to a pair of left and right lower down tubes 19 via one connecting member 18, and the lower down tube 19 is similarly formed of an extruded material, and is bent at the center to move backward. Extending.

The connecting member 18 is formed of an extruded material extruded in a direction perpendicular to a plane formed by the upper down tube 13 and the pair of left and right lower down tubes 19. The connecting member 18 has an upper mounting portion 18a formed by extrusion and having a U-shaped end, and a pair of lower mounting portions 18b. A rib 18c is formed in the shape of a letter C inside the upper mounting portion 18a.
A rib 18d is continuously formed on the wall facing the inside of 8b to ensure strength and rigidity.

The lower part of the upper down tube 13 is the upper mounting part 18 of the connecting member 18.
a, and the lower part of the reinforcing plate 14 is welded to the front side of the upper mounting part 18a so that the lower part of the reinforcing plate 14 is in contact with the front side of the rib 18c, and the rear part of the upper mounting part 18a is reinforced. The lower part of the plate 17 is joined and welded so as to fit on the rear side of the rib 18c.

The upper portions of the left and right lower down tubes 19 are inserted into the left and right lower mounting portions 18b of the connecting member 18, and the lower end of the connecting member 18 is sandwiched between the front and rear ends of the ribs 18d. The upper part of the pair of left and right lower down tubes 19 is connected to the connecting member by welding.
18 is connected to the lower mounting portion 18b.

By using the connecting member 18 formed of the extruded material as described above, the thickness can be freely changed according to the load applied to the upper down tube 13 and the lower down tube 19, and stable strength can be obtained. At the same time, it is possible to connect the down tubes with a smooth shape.
Furthermore, the welding of the connecting part can be reduced as much as possible,
Even in the case of mass production, variation in strength can be reduced.

The rear part of the pair of left and right lower down tubes 19 is a cross member
It is inserted and welded to a pair of right and left mounting portions 20a.
The cross member 20 is formed of an extruded material extruded in the left-right direction. Further, the cross member 20 is formed with holes 20b to 20d in the extrusion direction for weight reduction. The lower portions of a pair of left and right rear arm brackets 8 are welded to both sides of the cross member 20 in such a manner as to abut against a direction perpendicular to the axial direction of the cross member 20. The inside of the rear arm bracket 8 is covered with a lid 8a.

In addition, windows 20e and 20f are formed on the lower walls of the cross members 20 to define the holes 20b and 20c, respectively, to reduce the weight and discharge water, mud, and the like that enter the holes 20b and 20c downward. It has become. Furthermore, both sides 20 of the cross member 20
g is cut diagonally to secure the bank angle. Notches 20h are formed between the mounting portions 20a of the lower down tube 19, and both sides 20g are obliquely cut to avoid stress concentration. Furthermore, by fitting and welding the rear portions of the pair of left and right lower down tubes 19 to the mounting portion 20a, the strength can be secured without welding a reinforcing plate or the like, and the predetermined welding length can be easily adjusted. Can be secured.

A circular hole 20i is formed by extruding a hole formed in the cross member 20 from both sides in the left-right direction by extruding the hole. A bearing 21 is formed at the bottom of the circular hole 20i. A concave portion 22 is formed between the bearing portions 21, a support bolt 23 is inserted from one of the bearing portions 21, and a bearing portion 21 on the other side is formed.
The nut 24 is screwed into the screw portion inserted through the nut and screwed.

A pair of collars 25 are inserted into the support bolts 23 facing each other, and the ends of the vehicle body side links 28 of the link mechanism 27 are supported by the collars 25 via needle bearings 26. The portion is provided with an oil seal 29.

A pair of rear arm side links 30 is rotatably provided on the vehicle body side link 28 of the link mechanism 27, and the end of the rear arm side link 30 is turned to a bracket 32 of a cross member 31 provided between the left and right rear arms 10. It is movably provided. The lower end of the rear cushion 33 is located at the end of the vehicle body side link 28.
34 is pivotally supported, and an upper portion 35 of the rear cushion 33 is connected to a rear portion of the connection frame 15.

As described above, since the link mounting portion 36 of the link mechanism 27 is provided in the cross section in the side direction of the cross member 20 connecting the pair of right and left rear arm brackets 8 and the link fulcrum is within the width of the rear arm bracket 8, The load applied to the link mounting portion 36 can be received by the entire cross member 20, and local concentration of stress is reduced.

Also, an extension line L of the axis of the pair of lower down tubes 19 on the left and right.
However, when viewed from the plane direction, they are respectively directed to the center of the bearing portion 21, and no moment is applied to the cross member 20. Further, it is preferable that the extension line of the shaft of the lower down tube 19 is directed to the suspension of the respective bearing portions 21 even when viewed from the side.

Further, the protrusion 37a of the step mounting bracket 37 is fitted into the circular hole 20i of the cross member 20. The step mounting bracket 37 has a flange portion 37b to be joined to the outer surface of the rear arm bracket 8, and this flange portion 37b is joined to the outer surface of the rear arm bracket 8, and the bolt 38 is inserted through the flange portion 37b to It is screwed into the nut 39 fixed inside and bolted. A step 40 is mounted on the mounting portion 37c of the step mounting bracket 37.

The load applied to the step 40 can be received by the circular hole 20i of the cross member 20 via the step mounting bracket 37, and the load applied to the bolted portion for mounting the step mounting bracket 37 to the rear arm bracket 8 is reduced. Forty mounting strengths can be improved.

The rear cushion 33 is disposed behind the pair of left and right main frames 7 and is substantially along the main frame 7 therebetween.
The upper part 35 of this one rear cushion 33 is
The front of the connecting frame 15 is located below the main frame 7 and the upper down tube
The lower part of the head pipe 2 and the upper part of the rear cushion 33 are connected to each other by a single linear connection frame 15 via an upper down tube 13. The vicinity of the rear part of the connection frame 15 and the main frame 7 are connected by a cross member 41, and the middle part of the connection frame 15 and the middle part of the main frame 7 are connected by a cross member 42.

A seat rail 43 is attached to each of the pair of left and right main frames 7. The seat rail 43 is supported by the rear arm bracket 8 with a back stay 44, and a seat 45 is attached to the seat rail 43.

A recessed space 46 is formed behind the head pipe 2 by the left and right main frames 7 and the connection frame 15, and a fuel tank 47 is disposed in the recessed space 46.

Engine mounting bracket in the middle of the connection frame 15
The cylinder 49a of the engine 49 is mounted on the engine mounting bracket 48. Also Engine 4
The front side and lower part of 9 are attached to upper down tube 13 and lower down tube 19 via engine mounting brackets 50 and 51. Further, the rear side of the engine 49 is connected to a rear arm pivot 9 provided on the rear arm bracket 8,
It is pivotally supported together with the rear arm 10.

A carburetor 552 is connected to the rear side of the cylinder 49a of the engine 49, and an air cleaner 54 is further connected to the carburetor 52 via a duct 53.The duct 53 is located on the left side of the vehicle body so as not to interfere with the rear cushion 33. It is arranged near. The air cleaner 54 is seated behind the rear cushion 33.
It is arranged at a position below 45 so as not to interfere with the rear cushion 33.

An exhaust pipe 55 is connected to the front side of the cylinder 49a of the engine 49. The exhaust pipe 55 is bent from the left side to the right side of the vehicle body below the front side of the lower down tube 19, and extends rearward from the right side.

A pair of left and right radiators 56 are arranged in front of the engine 49, and each of the radiators 56 is an upper down tube 13
Attached to. This radiator 56 is a pipe 57,
The engine 49 is connected to the cylinder 49a of the engine 49 via 58, and circulates cooling water to cool the engine 49.

〔The invention's effect〕

As described above, according to the present invention, since the head pipe and the frame member to which the down tube is connected are integrally formed with the extruded material, the connection between the head pipe and the down tube uses a reinforcing plate or the like. In this case, the down tube may be welded to the frame member, and the assembling accuracy of the down tube is improved. In motorcycles such as motocross, for example, the load in the direction of the head pipe increases, but since the integral member of the head pipe and the frame member is formed of an extruded material extruded in the axial direction of the head pipe, the strength in the shear direction is improved. I do.

Furthermore, since the connection between the head pipe and the down tube is performed by the frame member, the welding length can be easily secured by welding the down tube to the frame member.

Further, the connection strength between the head pipe and the down tube can be easily secured by changing the thickness of the frame member, and stable strength can be obtained even in the case of mass production.

An upper down tube is welded and connected to the head pipe and the frame member, and a reinforcing plate is welded from a lower side of the frame member to a lower side of the upper down tube. Since the above connecting portion is reinforced, the connecting strength of the connecting portion between the head pipe and the upper down tube is high, since it is reinforced only by one reinforcing plate,
The connection structure of this connection part is simple.

Further, the connecting member has a U-shaped upper mounting portion and a pair of left and right lower mounting portions, a lower portion of the upper down tube is welded to an end of an upper mounting portion of the connecting member, and further, a front side of the upper mounting portion. Since the lower part of the reinforcing plate is welded to the lower part of the upper down tube is connected to the connecting member by this, the connecting member and the lower end of the upper down tube are firmly connected, and the reinforcing plate of this connecting part is Since the reinforcing plate for the connecting portion between the frame member and the distal end of the upper down tube is extended downward, the reinforcing structure using the reinforcing plate is simple, and the reinforcing effect of the reinforcing plate for both connecting portions is high.

Furthermore, the upper portions of the left and right lower down tubes are inserted into the left and right lower mounting portions of the connecting member, and the front and rear ends of the distal end thereof are combined with the lower mounting portion of the connecting member and welded. Thereby, since the upper parts of the pair of left and right lower down tubes are connected to the lower mounting part of the connecting member, the upper part of the lower down tube is firmly connected to the lower mounting part,
Further, since the forked portion is formed by an integral connecting member, the required strength and rigidity of the forked portion can be sufficiently secured.

As described above, the tip of one upper down tube is connected to the head pipe having the frame member, the lower end of the upper down tube is connected to the connecting member, and the lower mounting portion (bifurcated branch portion) on the left and right of the connecting member. A body frame having a structure in which a down pipe having one upper down tube connecting the ends of the left and right lower down tubes and a left and right lower down tube is connected to the head pipe is configured. The connection strength and rigidity between the tips are high, and the lower attachment portions (bifurcated portions) on the left and right sides of the connection member are not welded structures but molded products, so their strength and rigidity are high, and the left and right sides of the connection member are further improved. The connection strength and rigidity of the connection between the lower mounting part and the left and right lower down tube tips are high. Since the reinforcing plate for the connecting portion between the head pipe and the upper down tube extends downward and also serves as the reinforcing plate for the connecting portion between the upper down tube and the connecting member,
The reinforcing structure by the reinforcing plate is an extremely simple structure.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle to which the present invention is applied, and FIG.
FIG. 3 is a plan view of the vehicle body frame, FIG. 3 is an enlarged side view of the head pipe portion, FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3, FIG. Is a front view of the connecting portion of the down tube, FIG. 7 is a sectional view taken along line VII-VII of FIG. 6, FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 6, and FIG. FIG. 10, FIG. 10 is a bottom view of FIG. 9, FIG. 11 is a cross-sectional view of a mounting portion of the link mechanism, and FIG.
FIG. 11 is a sectional view taken along the line XII-XII, and FIG. 13 is a sectional view taken along the line XIII-XIII of FIG. Reference numeral 1 in the figure: body frame, 2: head pipe,
6 ... frame member, 7 ... main frame, 8 ...
Rear arm bracket, 9 ... Rear arm pivot, 10
…… Rear arm, 13 …… Top down tube, 15 …… Connection frame, 18 …… Connection member, 18a …… U-shaped upper attachment part, 18b …… A pair of left and right lower attachment parts (bifurcated branch part), 18c ,
18d Rib, 19 Bottom down tube, 20 Cross member, 27 Link mechanism, 33 Rear cushion, 38
…… Step mounting bracket, 40 …… Steps, 41, 42
... cross members, 49 ... engines.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62K 11/02-11/04 B62K 19/28

Claims (1)

(57) [Claims] 1. A head pipe and a frame member extending rearward and downward from the head pipe are integrally formed, and an integral member of the head pipe and the frame member is formed of an extruded material extruded in an axial direction of the head pipe. An upper down tube is connected to the frame member, and the frame member of the head pipe is composed of a pair of left and right plate-shaped portions suspended downward and rearward, and a pair of ribs connecting the plate-shaped portion and the head pipe, respectively. An upper down tube is welded and connected to the head pipe and the frame member, and a reinforcing plate is welded from a lower side of the frame member to a lower side of the upper down tube. And the connecting member is reinforced, and the connecting member comprises a U-shaped upper mounting portion and a pair of left and right lower mounting portions. The lower part of the upper down tube is welded to the end of the upper mounting part of the connecting member, and the lower part of the reinforcing plate is welded to the front side of the upper mounting part, whereby the lower part of the upper down tube is connected to the connecting member. The upper portions of the left and right lower down tubes are inserted into the left and right lower mounting portions of the connecting member, and the front and rear ends thereof are combined with the lower mounting portion of the connecting member and welded. hand,
Thereby, the body frame of the motorcycle in which the upper portions of the pair of left and right lower down tubes are connected to the lower mounting portion of the connecting member.