JP2673532B2 - Rear arm structure of motorcycle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rear arm structure capable of shortening a wheel base of a motorcycle.

(Prior Art) Conventionally, the rear arm structure of the motorcycle has been disclosed in
There is one disclosed in Japanese Patent Publication No. 61-125979.

According to this, the rear arm has a tubular body that extends in the vehicle width direction and is pivotally supported by the vehicle body frame so as to be rotatable about its axis, and extends rearward from both left and right ends of the tubular body. A pair of left and right arm portions is provided.

A connecting member that connects the cylindrical body and both arm portions to each other is provided, and the rear wheel is supported between the rear ends of the both arm portions. On the other hand, a shock absorber for buffering the shock transmitted from the both arm portions side to the vehicle body frame side is arranged between the front ends of the both arm portions.

The connecting member has a front end connected to the cylinder body, and left and right side ends connected to the both arm portions, and an upper surface plate, and a front end located below the upper surface plate and connected to the cylinder body. On the other hand, the left and right both ends are connected to the both arm portions, and the lower end plate is connected to the lower plate and the upper end is connected to the upper plate while the axial center extends in the vertical direction. And a cylindrical body that penetrates the upper and lower plates and accommodates the shock absorber in the inner hole.

(Problems to be Solved by the Invention) By the way, the rear arm receives not only the load of the vehicle body weight from the vehicle body frame and the shock absorber side but also the shocking load from the traveling road surface side through the rear wheel. Therefore, it is desired that the rear arm has sufficient strength.

Therefore, by attaching a reinforcing material to the connecting material,
Although it is possible to improve the strength of the rear arm, simply doing so may cause the following inconveniences.

That is, since the gaps in the front-rear direction between the rear wheel and the shock absorber and the connecting member are narrow, when the connecting member becomes large in the front-rear direction due to the reinforcement of the connecting member, the amount of the increase becomes large. Therefore, it is necessary to lengthen the arm part and position the rear wheel rearward. However, in this case, the wheel base becomes long, and there arises such a disadvantage that the operation becomes difficult to perform, for example, when making a quick turn.

(Object of the Invention) The present invention has been made by paying attention to the above-mentioned circumstances, and sufficiently reinforces the connecting member in the rear arm, and also prevents the wheel base from becoming long even with such reinforcement. The purpose is to

(Structure of the Invention) In order to achieve the above-mentioned object, a feature of the present invention is that a tubular body 26 extending in the vehicle width direction is pivotally supported on the vehicle body frame 2 so as to be rotatable about its axis, A pair of left and right arm portions 2 extending rearward from both left and right ends of the tubular body 26.
9 and 29 are provided, and a connecting member 34 that connects the cylinder body 26 and both arm portions 29 and 29 to each other is provided, and the rear wheel 9 is supported between the rear ends of both the arm portions 29 and 29, while the same as above. A shock absorber 11 for cushioning an impact transmitted from the arm portions 29, 29 side to the vehicle body frame 2 side is arranged between the front ends of the both arm portions 29, 29, and the connecting member 34 has the front end of the tubular body 26. On the other hand, the left and right ends are connected to the both arm portions 29, 29 while the top plate (43,
58, 59) and the front end located below the top plate (43, 58, 59) is connected to the cylinder body 26, while both left and right ends are connected to the arm portions 29, 29. The bottom plate (49,60) and the axial center extend vertically, and the upper end is the top plate (43,58,59).
On the other hand, the lower end is connected to the lower surface plate (49, 60) and the inner hole thereof penetrates the upper and lower surface plates to accommodate the shock absorber 11 in the cylindrical body (47, 50). ) And a rear arm structure for a motorcycle including: Is provided with a substantially X-shaped reinforcing member 45, and the left and right front ends of the reinforcing member 45 are connected to the left and right sides of the cylindrical body 26, while the reinforcing member 45 is
The left and right rear ends of the cylindrical body (47, 5
0) is positioned and the front portion of the reinforcing member 45 is connected to the cylindrical body (47, 50), and the upper edge of the reinforcing member 45 is connected to the upper surface plate (43, 58, 59). The lower end edge of the reinforcing member 45 is connected to the lower surface plate (49, 60).

(Operation) The operation of the above configuration is as follows.

That is, generally, the cylindrical shape has a large strength in the axial direction. The cylindrical body (47, 50) of the present invention has its axis extending vertically, and is connected to a midway portion of the tubular body 26 whose axis extends in the vehicle width direction.

Therefore, the cylindrical body 26 and the cylindrical bodies (47, 50) cooperate with each other to improve the strength of the connecting member 34 in mutually different directions, and the strength of the connecting member 34 does not have directionality and is entirely directional. It will be improved.

In addition, the tubular member 26 is formed by the reinforcing member 45 that is substantially X-shaped in plan view.
Since the left and right ends of the connecting member and the arm portions 29, 29 are connected, the connecting member 34 has a truss-like structure in plan view, and the strength of the connecting member 34 is effectively improved.

Moreover, the reinforcing member 45 is composed of the tubular body 26 forming the connecting member 34, and the left and right arm portions 29, 2 connected to the tubular body 26.
9. The cylinder 26 and the arm 29 are connected to the upper and lower plates and the cylinders (47, 50).

Therefore, the connecting member 34 has a shape in which a plurality of box-shaped bodies are connected to each other, and the strength thereof is further improved.

Therefore, the strength of the rear arm 8 is dramatically improved.

Then, when the strength of the rear arm 8 is improved as described above, as described above, the cylindrical body (47, 50) for accommodating the shock absorber 11 is connected to the cylindrical body 26, and the cylindrical body 26 And the cylindrical body (47, 50) are compact in the front-back direction.

Further, the reinforcing member 45 has a substantially X shape in a plan view, and the cylindrical body (47, 50) is formed in a region surrounded by the cylindrical body 26 and a front V-shaped portion of the front opening thereof. ) Together with the shock absorber 11, and since the rear portion of the reinforcing member 45 has a rear-opening substantially V-shaped groove shape, by fitting the outer peripheral portion of the rear wheel 9 therein, The wheel 9 can be located on the front side as much as possible, so that the reinforcing member 45, the cylindrical bodies (47, 50), and the rear wheel 9 are compact in the front-rear direction.

That is, as described above, the cylindrical body 26 and the cylindrical body (47, 50) are made compact in the front-rear direction, and the shape of the reinforcing material 45 is rationally utilized so that the reinforcing material 45 and the cylindrical body (47 ,Five
0), and the rear wheel 9 can also be made compact in the front-rear direction. Therefore, as described above, while the strength of the rear arm 8 is dramatically improved, the arm portions 29, 29 are lengthened. As a result, the rear wheel is prevented from being positioned further rearward, that is, the wheel base L is prevented from being lengthened.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1 to 7 show a first embodiment.

2 and 3, reference numeral 1 denotes a motorcycle, 2 denotes a body frame thereof, and the body frame 2 is a diamond frame. A front fork 3 is supported at the front end of the body frame 2 so as to be steerable. The front fork 3 supports a front wheel 4 at a lower end thereof, and supports a handle 5 at an upper end thereof.

A rear arm 8 is pivotally supported by a pair of left and right rear arm brackets 7, 7 provided at the rear end of the vehicle body frame 2, and a rear wheel 9 is supported on a swing end of the rear arm 8. Further, a shock absorber 11 is interposed between the rear portion of the vehicle body frame 2 and the rear arm 8 via a link mechanism 12, and the shock absorber 11 passes from the traveling road surface 13 through the rear wheel 9 and the rear arm 8 to the vehicle body. It absorbs the shock transmitted to the frame 2 side.

Reference numeral 15 denotes an engine. The engine 15 is supported on the vehicle body frame 2 by fastening bolts 16. Reference numeral 17 denotes a fuel tank. The engine 15 is provided with a drive wheel 20, while the rear wheel 9 is provided with a driven wheel 21,
A transmission chain 22 is wound around these chain wheels 20, 21. Then, the power of the engine 15 is transferred to the above-described transmission chain.
If the transmission is made to the rear wheel 9 via 22 or the like, the motorcycle 1 can run. In addition, 23 is a sheet.

Here, the shock absorber 11 and the link mechanism 12 will be described in more detail. The shock absorber 11 is composed of an expandable and contractible cylindrical damper 11a and a spring for urging the damper 11a in a direction to extend the damper 11a. The upper end is pivotally supported on the upper rear part of the body frame 2.

On the other hand, the link mechanism 12 includes the rear arm brackets 7, 7
Has a main link 12a rotatably supported at the lower end of the main link 12a, and the lower end of the damper 11a is rotatably supported at the rotating end of the main link 12a. Further, a pair of left and right connecting links 12b, 12b are pivotally supported in the middle of the main link 12a, and pivot ends of the respective connecting links 12b are pivotally supported by a bracket 12c provided on a lower surface of the rear arm 8 by a pivot pin 12d. Is pivoted by.

The link mechanism 12 reduces the damper 11a as the rear arm 8 pivots upward when the rear wheel 9 impacts the traveling road surface 13 while the motorcycle 1 is traveling and the rear arm 8 pivots upward. The amount is increased non-linearly, thereby improving the followability of the rear wheel 9 to the traveling road surface 13.

The rear arm 8 will be described in detail with reference to FIG. 1 and FIGS. 3 to 7.

The rear arm 8 is made of aluminum alloy or the like and is light and strong. That is, a pivot shaft 25 extending in the vehicle width direction is attached to the rear arm brackets 7, 7. Also,
A cylindrical body 26 having a circular cross section is coaxially fitted on the pivot shaft 25 so as to be coaxial with the pivot shaft 25, and the cylinder body 26 is rotatable about its axis by the left and right bearings. Is pivoted to.

A pair of left and right arm portions 29, 29 extends rearward from both left and right ends of the cylindrical body 26. Each of these arm portions 29 is made of sheet metal, and has a U-shaped outer member whose front end is welded to the tubular body 26.
30 and a front inner member 31 welded to the front side of the outer member 30.
And a rear inner member 32 having a U-shaped cross-section welded to the rear side of the outer member 30, and each arm 29 has a box-shaped cross section.

A connecting member 34 made of sheet metal is provided to connect the cylindrical body 26 and both arm portions 29, 29 to each other.

The connecting member 34 has a front member 35, and the front member 35 is an upper member 36, an intermediate member 37 and a lower member 38 which are stacked vertically.
, Which are welded together. And
The upper member 36 is the front inner member in each of the arm portions 29 described above.
The rear upper end 31a of the member 31 is connected to each other by welding, and the intermediate member 37 and the lower member 38 are connected to each other by welding the rear end 31b of the front inner member 31.

Further, the connecting member 34 has a rear member 40, and the rear member 40
Respectively project from the rear ends of the respective arm portions 29 in the forward upward inclination direction. The rear member 40 includes an outer member 41 integrally formed with the rear end of the outer member 30 of the arm portion 29, and an arm portion of the same as above.
29 has an inner member 42 integrally formed at the rear end of the rear inner member 32, and the outer member 41 and the inner member 42 of each of the rear members 40 are welded to each other to have a box-shaped cross section.

Each front end of the rear member 40 is bent inward in the vehicle width direction, and the rear upper end of the front inner member 31 in the arm portion 29 described above.
It is welded to 31a. In addition, the side plate 43 is welded across the front upper surface of the outer member 30 and the front inner member 31 in each of the above-mentioned arm portions 29, and more firmly connects the outer member 30 and the front inner member 31.

In particular, in FIGS. 1 and 7, a reinforcing member 45 is provided to reinforce the connecting member 34 and enhance the strength of the rear arm 8. The reinforcing member 45 is made of a metal plate and extends in the vertical direction, and has a substantially X shape in a plan view.

The left and right front ends of the reinforcing member 45 are connected to the left and right ends of the tubular body 26, while the left and right rear ends of the reinforcing member 45 are connected to the middle portions of the arms 29, 29 in the front-rear direction. .

More specifically, the reinforcing member 45 is provided with an upper body member 46 formed in an X shape in a plan view, and the left and right rear ends of the upper body member 46 are welded to the front surface of the intermediate member 37. ing. On the other hand, an arc plate 47 is welded to the front end of the upper body member 46. A lower main body member 48 is located below the upper main body member 46, and the lower main body member 48 is also formed in an X shape in plan view. The left and right rear ends of the lower body member 48 are integrally formed on the front surface of the lower member 38.

Further, the left and right front ends of the arc plate 47 and the lower body member 48 are welded to the front portion of the front inner member 31, and a front extension plate 55 extending forward from this weld portion is integrally formed with the front inner member 31. ing. The front extension plate 55 extends in substantially the same direction as the left and right front ends of the arc plate 47 and the lower body member 48 and is welded to the tubular body 26.

On the other hand, the left and right rear ends of the lower member 38 are the rear ends 31 of the front inner member 31.
A rear extension plate 56 that is welded to b and extends from the welded portion toward the rear outer side is integrally formed with the front inner member 31. The rear portion of the rear extension plate 56 is an outer member of the arm portion 29.
It is sandwiched between 30 and the rear inner member 32 and welded, and the rear end is abutted against the inner surface of the outer member 30 and welded.

That is, as described above, the reinforcing member 45 having a substantially X shape in plan view includes the intermediate member 37, the lower member 38, the upper main body member 46, the circular arc plate 47, the lower main body member 48, the front extension plate 55, and It is composed of a rear extension plate 56.

The arm portion 29 has a bent portion 30a formed by bending the front and rear halfway portions thereof, and the rear end of the rear extension plate 56 is welded near the bent portion 30a. That is, since the arm portion 29 is provided with the bent portion 30a, the arm portion 29 is
Even if the strength of the rear extension plate 56 decreases, the predetermined strength is supplemented to the arm portion 29 by the welding of the rear extension plate 56.

The upper surface of the upper body member 46 is closed by an upper surface plate 58 integrally formed with the upper member 36, and the cylindrical body 26 and other circular arc plates are closed.
The gap between the upper plate 59 and the lower plate 60 is also closed. In this case, the upper plate 58, 59 and the lower plate 60
Are welded to the corresponding members to improve the strength of the connecting member 34.

A bottom plate 49 connecting the lower ends of the lower body member 48 and the lower member 38 to each other.
Are integrally molded with these. The bottom plate 49 has a pair of left and right ribs 49a, 49a on its upper surface to improve the strength of the bottom plate 49.

In particular, as shown in FIGS. 5 and 6, the bracket
12c is provided corresponding to these ribs 49a, that is, the link mechanism 12 is firmly supported by the bottom plate 49.

In this embodiment, the lower member 38 and the lower body member 48 are
The bottom plate 49 is made of cast metal, but this may be made of metal plate or machined.

In particular, in FIG. 1, FIG. 6, and FIG. 7, the upper body member 46 and the circular arc plate 47 are superposed on the lower main body member 48 and welded to each other. In this case, the inner surface of the circular arc plate 47, The front surface of the lower body member 48 is substantially flush with the front surface. The left and right ends of the bottom plate 49 are the lower ends of the corresponding front inner member 31.
Each is welded to 31c.

Another arc plate 50 is provided to cover the arc concave surface formed by the inner surface of the arc plate 47 and the front surface of the lower body member 48, and the front edges of the arc plate 47 and the lower body member 48 and other arcs. Board 50
The trailing edge and the trailing edge are welded to each other, thereby forming a vertically oriented cylindrical body (47, 50) whose axial center extends in the vertical direction.

Between the left and right front ends of the reinforcing member 45, which is substantially X-shaped in a plan view, and is surrounded by the V-shaped portion of the front portion of the reinforcing member 45, which is a front opening, and the cylindrical body 26. The cylindrical body (47, 50) is arranged in the closed region, and the damper 11a of the shock absorber 11 is housed in the inner hole of the cylindrical body (47, 50).

Further, the outer peripheral portion of the front portion of the rear wheel 9 is fitted in the rear-opening substantially V-shaped groove portion of the rear portion of the reinforcing member 45.

A part of the circular arc plate 47 which is a part of the cylindrical body (47, 50) is also used as a part of the reinforcing member 45.

A cutout 52 having an arcuate shape in plan view is formed on the rear surface of the cylindrical body 26, and an arcuate cover plate 53 is welded so as to close the cutout 52. On the other hand, the other circular arc plate 50 is formed with a hole 54 that matches the notch 52. Then, the lid plate 53 welded to the tubular body 26
The other circular arc plate 50 is welded to the cylindrical body 26 so that the hole 54 and the hole 54 are fitted to each other, that is, the front portion of the cylindrical body (47, 50) is welded to the middle portion of the cylindrical body 26 in the vehicle width direction. Are connected by.

According to the above configuration, the other arc plate 50 can be positioned closer to the tubular body 26 by the amount that the front surface of the other arc plate 50 fits into the notch 52. Therefore, the damper 11a arranged between the circular arc plate 47 and the other circular arc plate 50 is
The wheel base L can be positioned on the front side, that is, the rear wheel 9 can be positioned on the front side accordingly, and the wheel base L can be shortened. In this case, the other arc plate 50 and the lid plate 53 may be integrated.

Here, in particular, referring to FIG. 1 and FIG.
In other words, the structure of 34 is described.

That is, the connecting member 34 has an upper surface plate whose front end is connected to the cylindrical body 26 and whose left and right ends are connected to the arm portions 29, 29. This top plate is the side plate 4 described above.
3, the upper surface plate 58, and the upper surface plate 59.

The connecting member 34 is located below the upper surface plate (43, 58, 59) and has a front end connected to the cylindrical body 26, and left and right side ends connected to the arm portions 29, 29. It is equipped with a bottom plate. The bottom plate is composed of the bottom plate 49 and the bottom plate 60 described above.

The upper end of the cylindrical body (47, 50) is the upper plate (43, 50).
58,59), while the lower end is the bottom plate (49,60)
And the inner hole thereof penetrates the upper and lower plate.

Further, the reinforcing member 45 is a member 37, 3 constituting this.
8,46,47,48,55,56, as a result already described, the upper edge is connected to the upper plate (43,58,59), while the lower edge is the lower plate (49,60). Are linked to.

(Second Embodiment) FIGS. 8 to 10 show another embodiment.

In the figure, reference numeral 26 denotes a tubular body, and a pair of left and right arm portions 29, 29 extend rearward from both left and right ends of the tubular body 26.
Each of the arm portions 29 includes a box-shaped front member 65 obtained by vertically stacking and welding a cast upper plate 63 and a lower plate 64, and a pipe-shaped rear member 66 welded to the rear surface of the front member 65. The front end of the front member 65 is welded to the tubular body 26.

A connecting member 34 that connects the cylindrical body 26 and the arm portions 29, 29 to each other.
Is provided. The connecting member 34 has a box shape in which a cast upper surface plate 68 and a lower surface plate 69 are vertically stacked and welded, and the connecting material 34 is integrally formed with the front member 65 of the arm portion 29. There is. In addition, the upper plate 68 and the lower plate of the connecting member 34.
Cylindrical body 70 is integrally molded in each of 69,
11a is located in this bore.

In the above structure, the connecting member 34 is provided with the reinforcing member 45 having a substantially X shape in a plan view. The reinforcing member 45 is the upper plate 68.
And ribs integrally formed on the inner surfaces of the lower plate 69.
The two ribs 71, 71 are shaped so as to match each other when the upper plate 68 and the lower plate 69 are vertically stacked.

The ribs 71 of the upper surface plate 68 are provided with six fitting holes 73 penetrating the upper surface plate 68, while the ribs 71 of the lower surface plate 69 are fitted with fitting projections 74 corresponding to the respective fitting holes 73. Is formed. When the upper surface plate 68 and the lower surface plate 69 are overlapped with each other, the fitting hole 73 and the fitting protrusion 74 are fitted to each other. In this state, the opening edge of the fitting hole 73 is inserted from above the upper surface plate 68. And mating protrusion
If the upper plate 68 and the lower plate 69 are welded to each other, the upper plate 68 and the lower plate 69 will be more firmly connected.

Although the above is based on the illustrated example, both upper surface plates 63 and 68,
One of the lower surface plates 64 and 69 may be made of sheet metal, or both of them may be made of sheet metal. Further, contrary to the illustrated example, a fitting protrusion 74 is provided on the upper surface plate 68 of the connecting member 34,
A fitting hole 73 may be provided in the lower surface plate 69.

 The other structure is the same as that of the first embodiment.

(Effect of the Invention) According to the present invention, the tubular body extending in the vehicle width direction is pivotally supported on the vehicle body frame so as to be rotatable about its axis, and extends rearward from the left and right ends of the tubular body. A pair of left and right arm portions are provided, a connecting member that connects the cylinder body and both arm portions to each other is provided, and a rear wheel is supported between the rear ends of the both arm portions.
On the other hand, a shock absorber for cushioning an impact transmitted from the both arm portions side to the vehicle body frame side is arranged between the front ends of the both arm portions, and the connecting member has the front end connected to the tubular body. An upper surface plate whose left and right ends are connected to both arm portions, and a lower end which is located below the upper surface plate and whose front end is connected to the cylindrical body, and whose left and right ends are connected to both arm portions. The face plate and the axis extend vertically and the upper end is connected to the upper plate, while the lower end is connected to the lower plate, and the inner hole penetrates the upper and lower plates to cushion the inner hole. In a rear arm structure of a motorcycle including a cylindrical body for accommodating a container, a front portion of the cylindrical body is connected to a middle portion in the vehicle width direction of the cylindrical body.

That is, generally, the cylindrical shape has a large strength in the axial direction. The axis of the cylindrical body in the present invention extends in the up-down direction, and is connected to the middle portion of the cylindrical body having the axis extending in the vehicle width direction.

Therefore, the cylindrical body and the cylindrical body cooperate with each other to improve the strength of the connecting member in different directions, and the strength of the connecting member is improved as a whole without directionality.

Further, according to the present invention, a reinforcing member configured by a plate member extending in the vertical direction and having a substantially X shape in a plan view is provided, and both left and right front ends of the reinforcing member are connected to the left and right ends of the tubular body, while the reinforcing member is provided. Both left and right rear ends of the material are connected to the both arm portions, the cylindrical body is positioned between the left and right front ends of the reinforcing material, and the same front portion of the reinforcing material is connected to the cylindrical body,
Moreover, the upper edge of the reinforcing member is connected to the upper plate, while the lower edge of the reinforcing member is connected to the lower plate.

That is, since the left and right ends of the tubular body and both arm portions are connected by the reinforcing member having an approximately X shape in a plan view, the connecting member has a truss-like structure in a plan view, and the strength of the connecting member is high. Effectively improve.

Moreover, the reinforcing member is slidably connected to the cylindrical body, the left and right arm portions connected to the cylindrical body, the upper and lower plates connected to the cylindrical body and the arm portions, and the cylindrical body.

Therefore, the connecting member has a shape in which a plurality of box-shaped bodies are connected to each other, and the strength thereof is further improved.

 Therefore, the strength of the rear arm is dramatically improved.

When the strength of the rear arm is improved as described above, as described above, the cylindrical body for accommodating the shock absorber is connected to the cylindrical body, and the cylindrical body and the cylindrical body are compact in the front-rear direction. Is configured.

Further, the reinforcing member has a substantially X shape in a plan view, and a shock absorber is arranged together with the cylindrical body in a region surrounded by a front opening substantially V-shaped portion and the cylindrical body. In addition, since the rear portion of the reinforcing member has a rear-opening substantially V-shaped groove shape, by fitting the outer peripheral portion of the rear wheel here, the rear wheel can be positioned as frontward as possible. Therefore, the reinforcing material, the cylindrical body, and the rear wheel are also compact in the front-rear direction.

That is, as described above, the cylindrical body and the cylindrical body are made compact in the language direction, and the reinforcing material 45 is rationally utilized so that the reinforcing material, the cylindrical body, and the rear wheel are also compact in the front-rear direction. Therefore, as described above, although the strength of the rear arm is dramatically improved, it is possible to prevent the rear arm from being positioned further rearward by lengthening the arm portion. The length of the wheel base is prevented from being lengthened, and the operation when making a quick turn can be facilitated.

[Brief description of the drawings]

1 to 7 show a first embodiment of the present invention, wherein FIG. 1 is a view taken along the line II of FIG. 3, FIG. 2 is a side view of the entire motorcycle, and FIG. FIG. 4 is a partially enlarged view of the drawing, FIG. 4 is a perspective view of the rear arm, FIG. 5 is a view taken along the line VV of FIG. 3, FIG. 6 is a view taken along the line VI-VI of FIG. 1, and FIG. Is a developed perspective view of the rear arm, FIGS. 8 to 10 show a second embodiment, FIG. 8 is a perspective view of the rear arm, FIG. 9 is a developed perspective view of the same rear arm, and FIG. 10 is X of FIG. It is a cross-sectional view taken along the line X-X. 1 ... Motorcycle, 2 ... Body frame, 8 ... Rear arm, 9 ... Rear wheel, 11 ... Shock absorber, 26 ... Cylindrical body, 29 ...
Arm part, 34 …… Connecting material, (43,58,59) ………… Top plate,
45 …… Reinforcement material, (47,50) …… Cylinder body, (49,60) …… Bottom plate, 68 …… Top plate, 69 …… Bottom plate, 70 …… Cylinder body.

Claims (1)

(57) [Claims] 1. A cylinder body extending in the vehicle width direction is pivotally supported on a vehicle body frame so as to be rotatable about its axis, and a pair of left and right arm portions extending rearward from both left and right ends of the cylinder body. Provided with a connecting member that connects the cylinder body and both arm portions to each other, the rear wheel is supported between the rear ends of both arm portions of the same as above, and the impact that is transmitted from the both arm portions of the same as above to the body frame side. A shock absorber for buffering the same is disposed between the front ends of the both arm portions, and the connecting member has a front end connected to the cylindrical body, while both left and right ends are connected to the both arm portions and a top plate. A lower plate which is located below the upper plate and whose front end is connected to the above-mentioned cylindrical body, and whose left and right ends are connected to both of said arm parts, and an axial center extending in the vertical direction and whose upper end is the above upper plate. While the lower end is connected to the lower surface plate and the inner hole is connected to the upper and lower surface plates, In a rear arm structure for a motorcycle including a cylindrical body that penetrates and accommodates the shock absorber in the inner hole, a front portion of the cylindrical body is connected to a middle portion in the vehicle width direction of the cylindrical body, and Providing a reinforcing member which is composed of an extending plate member and has a substantially X-shape in a plan view, the left and right front ends of the reinforcing member are connected to the left and right ends of the tubular body, while the left and right rear ends of the reinforcing member are connected to the both ends. Along with connecting to the arm portion, the cylinder is located between the left and right front ends of the reinforcing member and the front portion of the reinforcing member is connected to the cylindrical member, and the upper end edge of the reinforcing member is connected to the upper surface plate. A rear arm structure for a motorcycle in which the lower end edge of the reinforcing member is connected to the lower surface plate while being connected.