JP2995195B2 - Rear arm structure of motorcycle - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to a rear arm structure of a motorcycle, and more particularly to a rear arm structure of a motorcycle that reduces a resonance sound of a hollow box-shaped rear arm having a rectangular cross section.

[Background Art] As a rear arm of a motorcycle, for example, there is a rear arm of a pair of divided frame portions formed in a U-shaped cross section by press working and welded face to face to form a square. The hollow box-shaped rear arm having a square cross section has advantages such as light weight and rigidity as compared with a rear arm having a round cross section.

[Problems to be Solved by the Invention] Since such a rear arm has a wide flat portion, when the flat portion vibrates due to the driving of the internal combustion engine, the rear portion resonates to generate a resonance sound. The noise caused by the vibration of the hollow box-shaped rear arm having a rectangular cross section gives a rider a feeling of discomfort.

For this reason, in order to reduce the vibration of the flat portion of the hollow box-shaped rear arm, it is conceivable to increase the rigidity by increasing the thickness of the rear arm, but the weight increases and the production cost increases. There is.

The present invention has been made in view of such circumstances, and has as its object to provide a motorcycle rear arm structure that has a simple structure, suppresses vibration of a hollow box-shaped rear arm having a rectangular cross section, and reduces noise.

[Means for Solving the Problems] In order to solve the problems and achieve the object, the present invention is configured as follows.

The invention according to claim 1 is characterized in that the rear arm pivotally supported by the rear arm bracket has a pair of left and right arm portions, a support pipe is connected to a front side portion thereof, and the respective arm portions are slightly forward from the center portion. In a rear arm structure of a motorcycle, wherein a cross pipe to be connected is connected, and the support pipe is pivotally supported by a pivot shaft of the rear arm bracket, the arm portion has a hollow box shape having a vertically long section in the vertical direction, and The portion where the pipes are connected is wide in the vertical direction, narrows from the wide portion toward the front side and the rear side, and a flat portion behind the cross pipe is provided with a vibration damping device for suppressing vibration. The anti-vibration device
An elastic body made of a rubber material formed in advance is directly in contact with the inner surface of the outer wall of the arm portion in the vertical center, and a gap is formed between the upper and lower walls of the arm portion above and below the elastic body. A rear arm structure for a motorcycle, wherein the rear arm structure is assembled in a compressed state between the inner wall and the inner surface. ].

According to the first aspect of the present invention, the pair of left and right arm portions of the rear arm has a hollow box shape whose cross section is vertically long in the vertical direction, and a portion to which the cross pipe is connected is wide in the vertical direction. The portion becomes narrower toward the front side and the rear side, and the portion to which the cross pipe is connected is widened, and the rigidity is improved by providing the cross pipe.

Also, the flat portion of the arm portion behind the cross pipe is likely to generate vibration noise in a relatively large flat portion, but the elastic body made of rubber material is assembled in a compressed state, and the outer wall of the arm portion is mounted. Even when vibrates, the outer wall and the elastic body are always in contact with each other and do not separate from each other, so that the vibration absorbing function is sufficiently exhibited, and the rigidity is improved by forming a stick between the inner wall and the inner wall.

In addition, an elastic body made of a rubber material molded in advance is attached to the inner surface at the center in the vertical direction of the arm portion, and vibration can be absorbed in a portion of the outer wall where the vibration amplitude is largest, so that efficiency is high.

Furthermore, there is a gap between the upper and lower sides of the elastic body and the upper and lower walls of the arm, and when assembling the elastic body in a compressed state,
The assembling work is easy, and a space is provided for the rubber material to be deformed by receiving the vibration, so that the vibration can be effectively absorbed. As described above, since the rear arm is not made thick, vibration and resonance noise can be prevented while reducing the weight of the rear arm.

[Embodiment of the Invention] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a motorcycle having a motorcycle frame structure according to the present invention, FIG. 2 is a plan view of a rear arm partially cut away, and FIG. 3 is a side view of the rear arm.

In FIG. 1, reference numeral 1 denotes a body frame of a motorcycle. A front fork 3 is provided on a head pipe 2 constituting the body frame 1 so as to be pivotable, and a front wheel 4 is provided on the front fork 3. . A pair of left and right main frames 5 are provided on the head pipe 2, and a pair of left and right rear arm brackets 6 are provided at the rear of the main frame 5. The pair of left and right rear arm brackets 6 are integrally provided with a pair of left and right seat rails 7 that rise up diagonally rearward and extend rearward, and a seat 8 is placed on the seat rails 7.

An internal combustion engine 9 is mounted on the main frame 5 and the rear arm bracket 6, and a fuel tank 10 is mounted above the internal combustion engine 9 from the main frame 5 to the front side of the seat rail 7. Further, a fairing 11 covers from the front side of the front fork 3 to both sides of the internal combustion engine 9.

Rear arm 12 supported by rear arm bracket 6
Has a pair of left and right arms 12a, a front side 12a1 thereof is connected by a support pipe 13, and a cross pipe 14 is further connected slightly forward from the center. The support pipe 13 of the rear arm 12 is pivotally supported by a pivot shaft 15, and the rear arm 12 can swing about the pivot shaft 15. The rear arm bracket 6 and a bracket 16 provided on the cross pipe 14 of the rear arm 12 are connected by a link mechanism 17, and a rear cushion 18 is provided between the link mechanism 17 and the seat rail 7. A rear wheel 20 is supported at the rear of the rear arm 12 via an axle 19.

As shown in FIGS. 2 and 3, the arm portion 12a of the rear arm 12 has an outer divided frame portion 120 and an inner divided frame portion 1 formed by pressing aluminum and having a U-shaped cross section.
21 is formed by welding to form a frame having a square cross section. Upper end portion 120a and lower end portion 120 of outer divided frame portion 120
b is the upper end portion 121 and the lower end portion 121 of the inner divided frame portion 121.
b, the flat portion 120c of the outer split frame portion 120 and the flat portion 121c of the inner split frame portion 121 face each other.

The arm portion 12a of the rear arm 12 is provided with a vibration isolator 360 for suppressing vibration on a flat portion 120c formed on the outer divided frame portion 120.

In this embodiment, a rubber plate 362 is also fixed to the holding plate 361 of the vibration isolator 360. The rubber plate 362 of the holding plate 361 is applied to the inside of the flat portion 120c of the outer divided frame portion 120, and is pressed via the plate 364 by a bolt 363 screwed to a nut portion 121d formed integrally with the inner divided frame portion 121. I do. By the pressing of the bolt 363, the rubber plate 362 is moved via the holding plate 361 to the flat portion 120c of the outer divided frame portion 120.
, And the rubber plate 362 is held in a compressed state between the outer divided frame portion 120 and the holding put 361. With this vibration isolator 360, the vibration of the arm 12a is absorbed,
The anti-vibration device 360 is a bar between the outer divided frame part 120 and the inner divided frame part 121, and the rigidity of the arm part 12a is improved.

As described above, since the rear arm 12 having the rectangular cross section has a wide flat portion, even if the rear arm 12 vibrates due to driving of the internal combustion engine, the vibration is generated by the rubber plate 362 of the vibration isolator 360. 120 vibrations are absorbed, thereby suppressing resonance. Accordingly, the generation of the resonance sound of the rear arm 12 is reduced, and the noise caused by the vibration of the frame having the rectangular cross section is prevented from giving the rider a feeling of discomfort.

4 to 6 show still another embodiment applied to a rear arm. FIG. 4 is a plan view of the rear arm, FIG. 5 is a side view of the vibration isolator, and FIG. 6 is a rear arm of the vibration isolator. It is a perspective view which shows an attachment state.

The pair of left and right arms 12a includes an outer divided frame part 120 and an inner divided frame part 121 in the same manner as described above, and upper ends 120a and 121a thereof and lower ends 102b and 121b are welded to each other to form flat parts 120c and 121c. Are facing each other. The left and right rear arms 12 are provided with anti-vibration devices 140 at three locations.

As shown in FIG. 5, in this vibration isolator 140, a spacer 143 is fixed to a holding plate 142 having a rubber 141, and a nut 144 is fixed to the spacer 143 by brazing. A bolt 145 is screwed onto the nut 144, and a holding plate 147 having a rubber 146 is rotatably inserted into the bolt 145, and the holding plate 147 is positioned by a collar 148 fixed to the bolt 145. Is done.

As shown in FIG. 6, this vibration isolator 140
The rubber 141 of the holding plate 142 is inserted into the mounting hole 150 formed in the inner divided frame part 121 so that the rubber 141 of the holding plate 142 contacts the flat part 120c of the outer divided frame part 120, and the rubber 146 of the holding plate 147 is rotated by 90 degrees. Then, when the bolt 145 is rotated in this state while being brought into contact with the flat portion 121c of the inner divided frame portion 121, the interval between the two holding plates 142 and 147 is increased, and the rubbers 141 and 146 are pressed against the flat portions 120c and 121c. Also in this vibration isolator 140, the vibration of the rear arm 12 is absorbed and the rigidity is improved.

7 to 9, the front end 5a of the main frame 5 is attached to the head pipe 2 and the rear end 5b is attached to the rear arm bracket 6 by welding. The main frame 5 is formed by welding an outer divided frame portion 50 and an inner divided frame portion 51 having a U-shaped cross section formed by pressing aluminum,
The frame has a rectangular cross section. Outer split frame
The upper end 50a and the lower end 50b of the inner frame 50
Are welded to the upper end portion 51a and the lower end portion 51b, and the flat portion 50c of the outer divided frame 50 and the flat portion 51c of the inner divided frame portion 51 face each other.

The main frame 5 is provided with anti-vibration devices 60 for suppressing vibration of the frame at five locations, and the anti-vibration devices 60 are configured as shown in FIG. The rubber 62 of the holding plate 61 of the vibration isolator 60 is
The rubber 64 of the holding plate 63 is bonded to the inside of the flat portion 51c of the inner divided frame 51, respectively. A support stay 65 is provided between the holding plates 61 and 63, and the rubber stays 62 and 64 are separated by the support stay 65 into a flat portion 50c of the outer split frame portion 50 and a flat portion 51c of the inner split frame portion 51. Is pressed against.

As described above, since the main frame 5 having a rectangular cross section has a wide flat portion, the main frame 5 vibrates when the internal combustion engine is driven. This vibration is absorbed by the rubbers 62 and 64 of the vibration isolator 60, Thus, resonance is suppressed. Accordingly, the generation of the resonance sound of the main frame 5 is reduced, and the noise caused by the vibration of the frame having the rectangular cross section is prevented from giving the rider a feeling of discomfort.

Further, the vibration isolator 60 is a flat part 50 of the outer divided frame part 50.
c, provided between the flat portion 51c of the inner divided frame portion 51, the support stay 65 has the function of a hook bar, thereby, the flat portion 50c of the outer divided frame portion 50,
The rigidity of the inner divided frame portion 51 with the flat portion 51c is improved.

FIG. 10 is a sectional view showing another embodiment. In this embodiment, an anti-vibration device 70 is provided inside the flat portion 50c of the outer split frame portion 50 of the main frame 5 and the flat portion 51c of the inner split frame portion 51. This anti-vibration device 70 is rubber
The rubber 71 is bonded in a compressed state between the flat portions 50c and 51c, and absorbs vibration and improves the rigidity of the flat portion as described above.

FIG. 11 is a sectional view showing still another embodiment. In the vibration isolator 80 of this embodiment, the rubber 82 of the holding plate 81 is
Flat portion 50c of outer divided frame portion 50 of main frame 5
The rubber 84 of the holding plate 83 is also bonded to the inside of the inner divided frame portion 51. A bolt 85 penetrates through the flat portion 51c, the rubber 84, and the holding plate 83 from the outside of the inner divided frame portion 51, and is screwed to a nut 86 of the holding plate 81 of the outer divided frame portion 50.
With the rotation of, the rubber 82 is pressed against the outer divided frame portion 50 to the flat portion 50c via the holding plate 81.

Rubber 8 provided on the flat portion 51c of the inner divided frame 51
Since the fourth plate 4 and the holding plate 83 are not pressed against the flat portion 51c by the bolts 85, they function as dynamic dampers to suppress vibration.

 FIG. 12 is a sectional view showing another embodiment.

In the vibration isolator 90 of this embodiment, the rubber of the holding plate 91 is used.
92 is an outer divided frame portion forming the main frame 5
Adhered to the inside of the 50 flat part 50c. The flat portion 51c of the inner divided frame portion 51 is bent inward, and when a bolt 93 is penetrated from the outside thereof and tightened and fixed with nuts 94 and 95,
The rubber 92 is pressed against the flat portion 50c of the outer divided frame portion 50 by the bolt 93 via the holding plate 91.

[Effect of the Invention] As described above, according to the first aspect of the present invention, the pair of left and right arms of the rear arm has a vertically elongated hollow box shape in the vertical direction, and the portion to which the cross pipe is connected is vertically movable. It is wide in the direction, and narrows from the wide part toward the front side and the rear side. The part to which the cross pipe is connected is widened, and the rigidity is improved by providing the cross pipe.

Also, the flat portion of the arm portion behind the cross pipe is likely to generate vibration noise in a relatively large flat portion, but the elastic body made of rubber material is assembled in a compressed state, and the outer wall of the arm portion is mounted. Even when vibrates, the outer wall and the elastic body are always in contact with each other and do not separate from each other, so that the vibration absorbing function is sufficiently exhibited, and the rigidity is improved by forming a stick between the inner wall and the inner wall.

In addition, an elastic body made of a rubber material molded in advance is attached to the inner surface at the center in the vertical direction of the arm portion, and vibration can be absorbed in a portion of the outer wall where the vibration amplitude is largest, so that efficiency is high.

Furthermore, there is a gap between the upper and lower sides of the elastic body and the upper and lower walls of the arm, and when assembling the elastic body in a compressed state,
The assembling work is easy, and a space is provided for the rubber material to be deformed by receiving the vibration, so that the vibration can be effectively absorbed. As described above, since the rear arm is not made thick, vibration and resonance noise can be prevented while reducing the weight of the rear arm.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle to which the motorcycle frame structure of the present invention is applied, FIG. 2 is a plan view of a rear arm partially cut away, FIG. 3 is a side view of the rear arm, and FIGS. The figure shows still another embodiment applied to a rear arm, FIG. 4 is a plan view of the rear arm, FIG. 5 is a side view of the vibration isolator, and FIG. 6 is a perspective view showing a mounting state of the rear arm of the vibration isolator. , FIG. 7 is a side view of the main frame, FIG. 8 is a plan view of the main frame, FIG. 9 is a sectional view of FIG. IX-IX, FIG. 10 is a sectional view of another embodiment, FIG. Is a sectional view showing still another embodiment, and FIG. 12 is a sectional view showing another embodiment. In the figure, reference numeral 1 denotes a body frame, 5 denotes a main frame, 9 denotes an internal combustion engine, 12 denotes a rear arm, 50 and 120 denote outer split frame portions, 51 and 121 denote inner split frame portions, 60, 70, 80, 90, 100, and 11.
0,140,160,260,360 are vibration isolator devices.

Continued on the front page (72) Inventor Haruhito Okamoto 2500 Shinkai, Iwata-shi, Shizuoka Prefecture Inside Yamaha Motor Co., Ltd. Kensaku 2500 Shinkai, Iwata City, Shizuoka Prefecture Inside Yamaha Motor Co., Ltd. (56) References JP-A-62-184282 (JP, A) JP-A-1-297387 (JP, A) JP-A-56-8775 (JP, A) A) JP-A-62-184982 (JP, A) JP-A-62-77292 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B62K 11/02-11/04 B62K 25 / 20

Claims (1)

(57) [Claims] 1. A rear arm which is pivotally supported by a rear arm bracket has a pair of left and right arms, a support pipe is connected to a front side thereof, and furthermore, a cross pipe which connects the respective arms to a position slightly forward from the center. In the rear arm structure of a motorcycle in which the support pipe is pivotally supported by a pivot shaft of the rear arm bracket, the arm portion has a hollow box shape whose cross section is vertically elongated in the vertical direction, and the cross pipe is connected. Is widened in the vertical direction, narrows from the wide portion toward the front side and the rear side, and is provided with a vibration isolator for suppressing vibration in a plane portion behind the cross pipe. An elastic body made of a preformed rubber material is directly in contact with the inner surface of the outer wall of the arm section at the center in the up-down direction. Rear arm structure of a motorcycle according to that said to have been assembled in a compressed state between the inner wall inner surface so as to have a gap between the walls.