JP3412096B2 - Motorcycle body frame - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle body frame, and more particularly to a motorcycle body frame most suitable for traveling on uneven terrain, for example. 2. Description of the Related Art A body frame of a motorcycle supports a front wheel via a front fork on a front side, and a rear arm on a rear side by a link mechanism or a rear suspension. The rear wheel is supported by the rear arm. The engine is mounted on the main frame and down tube in the center. [0003] For example, there is a motorcycle shown in FIG. 12 for securing strength and rigidity in a motorcycle or the like running on uneven terrain. The body frame 100 of the motorcycle extends rearward from the upper portion of the head pipe 101, for example, the seat rail 1
02 has a single main frame 103 connected to a rear frame, and a single down tube 104 extending downward and rearward from a lower portion of the head pipe 101. A gusset 105 is provided between the main frame 103 and the down tube 104 from the left and right. , And a tension pipe 106 is welded and connected to the rear of the gusset 105. Further, the front side of one end of the tension pipe 106 and the gusset 105
The gusset 107 is welded from the left and right between the rear side and the down tube 104 from the left and right. At the other end of the tension pipe 106, a gusset 109 is also welded between the rear side and the main frame 103 from the left and right. [0004] As described above, the body frame is reinforced by separately welding the gusset and the tension pipe between the main frame and the down tube, and furthermore, at both ends of the tension pipe. Gussets are also welded to the welded parts to reinforce them, and there are problems such as a large number of parts and an increase in weight. For this reason, for example, it is conceivable to reinforce a large gusset from the head pipe to the area where the tension pipe of the main frame and the down tube is welded by welding from the left and right. In this case, the number of parts is reduced. However, the weight increases. Also, if a strong impact acts on the body frame during traveling, it is difficult to secure rigidity in a large flat portion of the gusset, and the flat portion may be wavy and deformed. The present invention has been made in view of such circumstances, and provides a body frame of a motorcycle in which gussets are reinforced to reduce the number of parts, reduce weight, and provide gussets with rigidity. It is intended to be. In order to solve the above object, according to an aspect of, the invention are according to claim 1, one main frame leading to the rear frame extends rearward Ri by the upper portion of the head pipe, the head pipe In the body frame of a motorcycle having one down tube extending downward and rearward from the lower part of the motorcycle and having an engine mounted below, a portion surrounded by three members of the head pipe, the main frame, and the down tube, 1 with left and right plates joined in a monaca shape
The gussets are arranged, the left and right plates are welded to the three members and integrated, and a space window is formed between the gusset and the main frame at an intermediate portion of the gusset, and the flat portion of the left and right plates is Forming a concave portion and a convex portion , a portion forming a spatial window of the left and right plates and a portion on the engine side,
Along the ends of the plane portions of the left and right plates ,
Bent inward after forming, the edges together after the bent butt welding, The portion to be welded to the main frame, and expanding the ends of the flat portions of the left and right plates outside the main The part welded to the frame and welded to the down tube forms the protrusion along the end of the flat part
Then, it is bent inward, and this bent portion is welded to the down tube. According to the first aspect of the present invention, one gusset in which the left and right plates are joined in a monaka shape is disposed at a portion surrounded by the three members of the head pipe, the main frame, and the down tube. By welding the left and right plates to the three members and integrating them, the head pipe, the main pipe, and the down tube can be reinforced while reducing the number of parts. In addition, a space window is formed between the gusset and the main frame at an intermediate portion of the gusset, so that the gusset is lightweight and a portion forming the space window of the gusset is connected by welding to have a rib function. Thus, the strength and rigidity of the gusset are improved. Further, since unevenness is formed on the flat portions of the left and right plates of the gusset, even if a strong impact acts on the vehicle body frame during traveling, the large left and right flat portions can be prevented from waving and deformation can be prevented. The portion forming the space window of the left and right plates, the portion on the engine side, and the portion welded to the down tube are bent inward after forming a convex portion along the end of the flat portion. Therefore, the convex portion functions as a rib, and the strength and rigidity of the gusset are improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motorcycle body frame according to the present invention will be described below in detail with reference to the accompanying drawings. 1 is a side view of the motorcycle, FIG. 2 is a side view of the vehicle body frame, FIG. 3 is a view taken in the direction of arrow A in FIG. 2, FIG. 4 is a view taken in the direction of arrow B in FIG. Is a side view of the gusset, and FIG. 6 is FIG.
FIG. 7 is a sectional view taken along the line VII-VII of FIG. 5, FIG. 8 is a sectional view taken along the line VIII-VIII of FIG.
Is a cross-sectional view along the line IX-IX in FIG. 5, and FIG.
FIG. 11 is a sectional view taken along the line XI-XI in FIG. This motorcycle is used, for example, for motocross competitions running on rough terrain. A front fork 3 is supported on a head pipe 2 constituting a body frame 1, and a lower end of the front fork 3 Is provided with a front wheel 4. Further, a front fender 5 is attached to the front fork 3, and the front fender 5 is a fixed fender that does not interlock with the vertical movement of the front wheel 4. At the upper part of the head pipe 2, a front part 8a of one main frame 8, which extends rearward and is connected to the mounting part 7 of the rear suspension 6, is welded. The main frame 8 is formed to have a circular cross section, and a rear portion 8b is welded to a mounting portion 7 of a rear suspension 6 as shown in FIG. 3, and a pair of right and left rear pipes 9 are welded to the mounting portion 7. The rear arm bracket 10 is welded to the lower part of each. A rear pipe 9 is welded to a mounting portion 7 of the rear suspension 6, and a seat rail 16 is connected to the mounting portion 7, thereby forming a rear frame F. The left and right rear arm brackets 10 are connected by a cross member 90 to be integrated. A rear arm pivot 11 is provided between the rear arm brackets 10, and a rear arm 12 is pivotally supported on the rear arm pivot 11.
Is supported. The rear arm 12 is supported by a vehicle body side mounting portion 15 by a link mechanism 14, and the vehicle body side mounting portion 15 is welded to a cross member 90. The link mechanism 14 supports the lower portion 6a of the rear suspension 6, and the mounting portion 7 supports the upper portion 6b of the rear suspension 6. As described above, the rear arm 12 is provided so as to be vertically swingable by the link mechanism 14 and the rear suspension 6. The front part 16 of the seat rail 16 is attached to the mounting part 7.
The upper part 17a of the left and right back stays 17 is welded to the rear part 16b, and the lower part 17b is attached to the mounting part 18 welded to the rear arm bracket 10. A fuel tank 19 is arranged on the upper part of the main frame 8 so as to straddle it. A front part of the seat 20 placed on the seat rail 16 covers an upper part of the fuel tank 19. An upper portion 21a of one down tube 21 extending downward and rearward is welded to a lower portion of the head pipe 2. The down tube 21 is formed in a rectangular cross section, and front portions 22a of left and right support frames 22 are welded to lower portions 21b from both sides as shown in FIG.
The gusset 23 between the inside of the down tube 21 and the lower portion 21b of the down tube 21 is reinforced by welding. The rear portion 22b of the support frame 22 is welded to the cross member 90, and the connection frame 24 is further reinforced by welding between the rear portion 22b of the support frame 22 and the rear arm bracket 10. A pair of mounting cylinders 25 are fixed to the center of the support frame 22. An engine mounting bracket 26 is applied to the mounting cylinder 25 from the outside, and screws 27 are attached to the mounting cylinder 25.
And the engine mounting bracket 26 is mounted. An engine mounting bracket 28 is welded to a rear portion 22b of the support frame 22. The upper part of the head pipe 2 and the main frame 8
A gusset 29 is welded to the upper part of the front part, and a gusset 30 is similarly welded to the lower part of the head pipe 2 and the upper part 21a of the down tube 21. Thus, the gussets 29, 30 are welded from above and below. It is reinforced by connecting. A head pipe 2, a main frame 8,
A gusset 33 in which the left and right plates 31 and 32 are joined in a monaka shape is welded and integrated into a portion surrounded by the down tube 21, and a space window 34 between the gusset 33 and the main frame 8 is provided at an intermediate portion. Are formed, and irregularities are formed on the plane portions of the left and right plates 31, 32. That is, the right and left plates 3 of the gusset 33
Reference numerals 1 and 32 denote portions 31a and 32a forming the space window 34.
And the outer engine-side portions 31b, 32b are welded. By forming the space window 34 between the main frame 8 and the middle portion of the gusset 33 in this way, the gusset 33 is lightweight and the space window 34 of the gusset 33 is formed.
Is welded to form a rib,
Thereby, the strength and rigidity of the gusset 33 are improved. The left and right plates 3 of the gusset 33
1 and 32 are portions 31c to be welded to the head pipe 2;
32c, parts 31d, 3 welded to the main frame 8
2d, parts 31e, 3 welded to the down tube 21
By welding these portions to the head pipe 2, the main frame 8, and the down tube 21 without welding 2e, the three members are integrated and reinforced. The left and right plates 31 of the gusset 33
32, concave portions 31f and 32f and convex portions 31
g, 32g, the unevenness is formed, the left and right plates 3
The flat portions 1 and 32 are concave portions 31 f and 32 f and the convex portion 31.
By forming g and 32g, strength and rigidity are improved. Therefore, even if a strong impact acts on the body frame 1 during traveling, the large flat portions of the left and right plates 31, 32 are prevented from waving, and can be prevented from being deformed. Further, the projections 31h and 32h are formed by bending at the ends of the plane portions of the left and right plates 31 and 32, and the projections 31h and 32h have a rib function. The strength and rigidity of the left and right plates 31, 32 are improved. The right and left plates 31, 32 of the gusset 33
A pair of mounting cylinders 40 are welded to the rear part of the engine.
2 is screwed into the mounting cylinder 40 to mount the engine mounting bracket 41
Is attached. An engine 43 is mounted below the gusset 33 in a space surrounded by the rear pipe 9, the support frame 22, and the rear arm bracket 10 from the side. In the engine 43, the upper portion of the cylinder 43a is supported by tightening bolts 44 to the engine mounting bracket 41, the front side of the engine case 43b is supported by tightening bolts 45 similarly to the engine mounting bracket 26, and the lower side is the engine mounting bracket 28. The rear side is supported by a rear arm bracket 10 via a rear arm pivot 11. A carburetor 47 is connected to the rear side of the cylinder 43a of the engine 43.
8, an air cleaner 49 is connected to this duct 4,
Numeral 8 is arranged on the left side of the vehicle so as not to interfere with the rear suspension 6. Further, the air cleaner 49 is arranged at a position below the seat 20 behind the rear suspension 6 so as not to interfere with the rear suspension 6. An exhaust pipe 5 is provided in front of the cylinder 43a of the engine 43.
The exhaust pipe 50 is bent from the left side to the right side of the vehicle below the front side of the support frame 22 and extends rearward from the right side. An ignition unit 51 is disposed at a position of the space window 34 formed between the gusset 33 and the main frame 8. The ignition unit 51 is supported by a bracket 52 welded to the main frame 8, and the ignition unit 51 is arranged using the space window 34. As described above, according to the first aspect of the present invention, the left and right plates are joined in a monaka shape to the portion surrounded by the three members of the head pipe, the main frame, and the down tube. By disposing the gussets and welding the left and right plates to the three members and integrating them, the head pipe, the main pipe, and the down tube can be reinforced while reducing the number of parts. Furthermore, a space window is formed in the middle of the gusset between the main frame and the gusset, so that the gusset is lightweight and the portion forming the space window of the gusset is connected by welding to function as a rib. The strength and rigidity of the gusset are improved. Further, since irregularities are formed on the flat portions of the left and right plates of the gusset, even if a strong impact acts on the vehicle body frame during traveling, large right and left flat portions can be prevented from waving and deformation can be prevented. The portion forming the space window of the left and right plates, the portion on the engine side, and the portion welded to the down tube are bent inward after forming a convex portion along the end of the flat portion. Therefore, the convex portion functions as a rib, and the strength and rigidity of the gusset are improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a motorcycle. FIG. 2 is a side view of the vehicle body frame. FIG. 3 is a view as viewed from an arrow A in FIG. 2; FIG. 4 is an arrow view as viewed from a direction B in FIG. 2; FIG. 5 is a side view of the gusset. 6 is a sectional view taken along the line VI-VI in FIG. FIG. 7 is a sectional view taken along line VII-VII in FIG. FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. FIG. 9 is a sectional view taken along line IX-IX in FIG. 5; FIG. 10 is a sectional view taken along line XX of FIG. 5; 11 is a sectional view taken along the line XI-XI in FIG. FIG. 12 is a side view of a body frame of a conventional motorcycle. [Description of Signs] 1 Body frame 2 Head pipe 6 Rear suspension 7 Mounting part 8 Main frame 21 Down tubes 31, 32 Plate 33 Gusset 34 Space window F Rear frame

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Claims (1)

(57) one main frame leading to Claims 1. A rear frame extending rearward Ri by the top of the head pipe, the single down tube extending downward rearward from a lower portion of the head pipe A gusset having left and right plates joined in a monaka shape to a portion surrounded by three members of the head pipe, the main frame, and the down tube; arranged and integrated by welding lateral plates of the third member, with an intermediate portion of the gusset to form a space windows between the main frame, the recesses and projections on the flat portion of the left and right plate A part forming the space window of the left and right plates and a part on the engine side are formed along the ends of the plane parts of the left and right plates.
After forming the protruding portion, it is bent inward, and the edges after this bending are butt-welded, and the portions to be welded to the main frame are such that the ends of the plane portions of the left and right plates are directed outward. The part to be expanded and welded to the main frame, and the part to be welded to the down tube is an end of a flat part
After forming the convex portion along, bend inward, this bending
A body frame of a motorcycle, wherein a portion is welded to the down tube.