JPH0761792B2 - Rear arm support link mounting mechanism for motorcycles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an attachment mechanism for attaching a rear arm support link arranged below a rear arm of a motorcycle to a rear arm, and a cross member for attaching the rear arm support link. By utilizing the above, it is possible to eliminate the welding of the mounting bracket to the rear arm and solve the problems of thermal distortion and residual stress of the rear arm due to the welding, and shorten the length of the rear arm as much as possible. The wheelbase of the vehicle body can be shortened.

[Conventional technology]

A rear arm support link (link mechanism) is below a rear arm connecting left and right arms to each other by a cross member. A piston rod of a hydraulic shock absorber is connected to the rear arm support link, and the shock absorber is connected via the rear arm support link. In motorcycles where the rear arm is supported by, the left and right arms are connected to each other through the cross members by welding both ends of the cross member to the side surfaces of the left and right arms, and the rear arm support link mounting bracket is welded to the lower surface of the rear arm. ing.

In order to reduce the weight of this type of rear arm, it is desirable that the thickness of the rear arm be as small as possible, so weld the above-mentioned rear arm support link mounting brackets to the undersides of the left and right arms as thin as possible. The position of the mounting bracket is selected in consideration of the lever ratio of the link mechanism within the range where the shock absorber and the link mechanism do not interfere with each other, and the position of the cross member within the range where the shock absorber does not interfere with the rear wheel. Considering the distance between However, a considerably high welding strength is required for the welded portion of the mounting bracket, which is repeatedly subjected to a large shocking load during the operation of the motorcycle. Therefore, in order to secure this welding strength, the length of the welding line between the mounting bracket and the lower surfaces of the left and right arms must be considerably long. As a result of welding the mounting bracket to the lower surfaces of the left and right arms, which are relatively thin, with a long welding line, the problems of thermal strain and residual stress of the arm due to welding remain. Further, although it is a problem of positioning accuracy of welding work and a problem caused as a result of thermal distortion, there remains a problem of accuracy of positions of the mounting brackets welded to the lower surfaces of the left and right arms.

[Problems of the Invention]

An object of the present invention is to solve the above problem, and to devise a rear arm mechanism and structure so that the mounting brackets can be appropriately provided without welding the mounting brackets to the lower surfaces of the left and right arms in the above-mentioned conventional technique. To do.

[Means taken to solve the problem]

The measures taken to solve the above problems are as follows:
It is composed of (b).

(A) A rear arm support link mounting bracket is integrally provided on the lower surface of the cross member welded to the side surface of the rear arm so as to project downward when the cross member is molded, and the arm side link of the link mechanism is connected to the mounting bracket. (B) The center line C ₁ of the mounting bracket is inclined rearward with respect to the vertical center line C ₂ of the cross member so that the cross section of the cross member and the mounting bracket has a dogleg shape. The letter-shaped inclination should be set so as to substantially follow the outer circumference of the rear wheel.

The above-mentioned "projected downward integrally with the cross member" means that the mounting bracket is formed so as to integrally project downward when the cross member is molded by a molding method such as extraction molding.

[Operation] Since the mounting bracket is preliminarily projected on the lower surface of the cross member as described above, there is no problem in terms of strength of the rear arm and machining accuracy due to the projection of the mounting bracket.
Rather than fixing the bracket to the lower surface of the cross member by welding or other means to project the mounting bracket on the lower surface of the cross member, the bracket was formed during molding, so the mounting bracket and the cross member main body The bond strength between them is sufficiently secured, and there are no problems with the mounting position, processing accuracy, etc.

If the mounting bracket is projected on the bottom surface of the cross member, its position in the front-rear direction is uniquely determined by the front-rear position of the cross member, so the front-rear position of the cross member is restricted in relation to the rear wheel. As a result, the position of the mounting bracket cannot be appropriately selected because it is possible (it can be positioned as rearward as possible within the range where it does not interfere with the rear wheel). For this reason, it is unavoidable that the moment arm of the supporting force of the hydraulic shock absorber with respect to the rear arm, or the lever ratio, is restricted as compared with the conventional case. However, the mounting bracket is projected from the lower surface of the cross member with a rearward inclination (the center line C ₁ of the mounting bracket is inclined rearward with respect to the vertical center line C ₂ of the cross member and the cross member and the above-mentioned mounting bracket). The cross-sectional shape of and is made to be a dogleg shape so that the dogleg shape is approximately along the outer periphery of the rear wheel), so that the connecting point of this mounting bracket and the rear arm support link is more than the cross member. It can be positioned rearward, and the position of the connecting point in the front-rear direction (particularly positioned rearward) can be appropriately selected by selecting the inclination angle.

If the mounting bracket is simply projected downward from the lower surface of the cross member, when the rear arm pivots largely downward, the lower end of the shock absorber cylinder interferes with the mounting bracket, while the rear arm pivots largely upward. At this time, the lower end of the cylinder of the shock absorber may interfere with the arm side link. However, the mounting bracket is projected from the lower surface of the cross member with a rearward inclination (the center line C ₁ of the mounting bracket is inclined rearward with respect to the vertical center line C ₂ of the cross member and the cross member and the above-mentioned mounting bracket). Since the cross-sectional shape of and is formed in a dogleg shape so that the dogleg shape is substantially along the outer periphery of the rear wheel.), The above interference can be avoided.

Therefore, by mounting the mounting bracket on the above-mentioned elements (a) and (b), that is, the lower surface of the cross member and inclining the mounting bracket rearward with respect to the vertical center line of the cross member, the mounting bracket is The above problem can be sufficiently solved without causing a new problem such as interference with the lower end of the cylinder of the shock absorber.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

A front fork 3 is rotatably provided on a head pipe 2 of a vehicle body frame 1, and a front wheel 4 is attached to a lower end of the front fork.

The rear portions of the main frame 5 and the down tube 6 welded to the head pipe 2 are connected to each other via a rear bracket frame 7.

Rear wheels 9 are supported on the body frame 1 via a rear suspension 10, and the rear suspension 10 is composed of a rear arm 11, a link mechanism 12 and a shock absorber 13.

The rear arm 11 is composed of a pair of arm portions 11a, the tip of which is supported by a rear arm bracket 14 of the vehicle body frame 1.
It is pivotally supported by 15, and the axle of the rear wheel 9 is attached to the rear end portion. The driving force from the internal combustion engine 8 is transmitted to the rear wheels 9 via the chain 16.

The link mechanism 12 is composed of a vehicle body side link 17 and an arm side link 18. A rotating shaft portion 17a formed at one end of the vehicle body side link 17 is rotatably connected to a bracket 19 welded to the rear bracket frame 7 via a support shaft 20, and is formed at the other end thereof. The shaft portion 17b is pivotally supported by the support shaft 21.

The arm side link 18 is a pair of left and right, one end of which
18a is rotatably connected to a rotation shaft portion 17b of a vehicle body side link 17 via a support shaft 21. The other end 18b of the arm side link 18 is rotatably connected to a mounting bracket 22 via a support shaft 23.

The mounting bracket 22 is formed integrally with the cross member 25 by a pipe-shaped extruded member 24 made of, for example, an aluminum alloy or a magnesium alloy. As shown in FIG. 4, the mounting bracket 22 is formed by cutting both sides below the cross member 25, and the mounting bracket 22 has an axial hole.
27 is formed to reduce the weight.

The center line C _{1 of} this mounting bracket 22 is a cross member 25.
Is inclined backward at an angle θ with respect to the vertical centerline C ₂ .

Both sides of the cross member 25 in the axial direction are welded to the arm portion 11a of the rear arm 11, and the mounting bracket 22 is positioned at a predetermined position of the rear arm 11 by welding the cross member 25 to the arm portion 11a.

Since the center line C _{1 of the} mounting bracket 22 is inclined rearward with respect to the vertical center line C ₂ of the cross member 25 at an angle θ, the support shaft 23 of the mounting bracket 22 and the arm side link 18
The connecting point by is located behind the extension of the center line C ₂ of the cross member 25. As the inclination angle increases, the connecting point is located rearward, the distance between the support shaft 23 and the support shaft 21 increases, and the moment arm or lever ratio of the support force of the shock absorber 13 increases.

A lower end portion 13a of the shock absorber 13 is rotatably connected to a support portion 17b formed on a rotation shaft portion 17b of a vehicle body side link 17 via a support shaft 28, and an upper end portion 13b is pivotally supported on the vehicle body frame 1. Has been done.

The load of the vehicle body applied to the rear arm 11 is transmitted to the shock absorber 13 via the link mechanism 12, and the shock absorber 13 pushes the rotating shaft portion 17b of the link mechanism 12 downward and the force of pushing the vehicle body frame 1 and the rear arm 11 is reduced. The balance supports the load of the vehicle body and damps vibrations caused by unevenness on the road surface.

At this time, the arm side link 18 of the link mechanism 12 is supported by the mounting bracket 22, and the load applied to the mounting bracket 22 is received by the cross member 25 formed integrally.

The mounting bracket 22 is provided so as to project integrally with the cross member when the cross member 25 is formed by extrusion molding or the like, and the mounting bracket 22 is fixed by welding both ends of the cross member 25 to the side surfaces of the arm portion 11a. It is integrated with the rear arm 11 via 25 and its positioning is performed. Therefore, no special welding is required to integrate the mounting bracket 22 with the rear arm 11, and the mounting bracket 22 is moved backward from the lower surface of the cross member 25 by an angle θ.
Since it is tilted, the connection point between the mounting bracket 22 and the arm side link 18 can be selected as rearward as possible by appropriately selecting this tilt angle θ.

Further, since the mounting bracket 22 and the cross member 25 are integrally formed so as to project, the width of the cross member in the front-rear direction can be narrowed as much as possible within a limit that can secure necessary strength against twisting. Therefore, the width of the cross member 25 in the front-rear direction is reduced, so
Can be shifted forward, and since the mounting bracket 22 is inclined rearward with respect to the cross member 25, the lower end of the cylinder of the shock absorber 13 and the mounting bracket 22 can be displaced.
It can be moved further forward while avoiding interference with.
Even if the mounting bracket 22 is tilted rearward with respect to the cross member 25, the rear end surface has a shape along the outer periphery of the rear wheel 9, so that interference with the mounting bracket 22 or the rear wheel 9 of the cross member 25 is avoided. The above does not hinder anything.

Therefore, the above-mentioned position of the cross member 25 must be a position that does not interfere with the shock absorber and can maintain a predetermined distance from the rear wheel, and the position of the cross member 25 and the mounting bracket is limited. By devising the structure of 22, the rear arm 11 can be reasonably shortened to shorten the wheelbase of the vehicle body (the position of the rear wheel can be brought closer to the front wheel).

Further, in the prior art, when the mounting bracket is simply provided on the lower surface of the cross member 25 and the position of the cross member 25 is shifted forward, the position of the mounting bracket 22 moves forward, and for this reason, the arm of the link mechanism 12 is moved. The length of the side link 18 becomes short, the lever ratio of the link mechanism 12 becomes small, and the cushioning characteristic deteriorates. But the mounting bracket
By tilting 22 toward the rear with respect to the cross member 25, the above problem caused by shifting the position of the cross member 25 to the front, that is, the link on the arm side of the link mechanism 12
It is possible to solve the problem that 18 becomes short and avoid the deterioration of the above-mentioned buffer characteristic. Incidentally, reference numeral 26 is a cutting portion on both sides of the mounting bracket 22.

〔The invention's effect〕

The invention that solves the above problems of the present invention is not known. Therefore, since the subject of the present invention is a novel subject, solving the subject and solving the above-mentioned problems of the prior art is an effect peculiar to the present invention.

That is, thermal distortion caused by welding the mounting bracket to the lower surface of the relatively thin rear arm with a long welding line,
Completely eliminating the problem of residual stress is an effect peculiar to the present invention.

Further, when the mounting bracket is provided on the lower surface of the cross member by inclining the mounting bracket rearward, the connection point between the mounting bracket and the rear arm support link can be positioned rearward as much as possible, whereby the shock absorber is provided. Rear arm support force moment arm by
It is an effect peculiar to the present invention that it is possible to improve the cushioning characteristics of the cushioning device by selecting the lever ratio as large as possible.

Further, even if the space between the left and right arm-side links 18, 18 is narrow, and therefore the lower end of the shock absorber 13 interferes with the arm-side links 18, 18 or the mounting bracket, the mounting bracket 22 is inclined rearward. , And mounting bracket 22
Tilt backwards to attach the arm side link 18 and mounting bracket
By locating the connection point with 22 as rearward as possible, the inclination angle of the arm-side link 18 to the rear of the vehicle body becomes large, so that the lower end of the shock absorber 13 is connected to the arm-side links 18, 18,
Alternatively, it is possible to prevent interference with the mounting bracket 22.

In addition, from another point of view, it can be said that the present invention produces the following remarkable unique effects.

In the first place, the above-mentioned conventional technology, that is, the rear arm support link mounting mechanism of the motorcycle in which the lower end of the shock absorber is connected to the link mechanism arranged below the rear arm through the space between the left and right arm parts When the bracket is projected and the lower end of the shock absorber is connected to this, the position of the cross member is
Alternatively, there is a constraint that the mounting bracket or the like must be in a position where it does not interfere with the lower end of the cylinder of the shock absorber and can maintain a predetermined distance from the rear wheel. On the other hand, when the mounting bracket is welded to the cross member so as to project therefrom, the width of the cross member in the vehicle body front-rear direction must be widened in order to secure the length of the welding line. The width of the cross member has to be widened not because of the strength requirement of the cross member but because of the secondary requirement of ensuring the length of the welding line of the mounting bracket. It becomes an obstacle in doing.

On the other hand, according to the present invention, by mounting the mounting bracket integrally with the cross member by molding, the width of the cross member in the front-rear direction can be narrowed as much as possible within a limit that can secure necessary strength against torsion. be able to. Therefore, it is possible to shift the position of the cross member forward by an amount corresponding to the narrowing of the width of the cross member in the front-rear direction, and further, since the mounting bracket is inclined rearward with respect to the cross member, the lower end of the cylinder of the shock absorbing device is And the mounting bracket or the arm-side link can be prevented from interfering with each other and can be further moved forward. Even if the mounting bracket is tilted rearward with respect to the cross member, since the rear end face has a shape along the outer periphery of the rear wheel, there is no hindrance in avoiding interference with the rear wheel (buffer in FIG. 2). (See the positional relationship between the lower end of the cylinder of the device 13, the cross member 25 and the mounting bracket 22, and the outer peripheral surface of the rear wheel 9).

Therefore, according to the present invention, the position of the above-mentioned cross member must be “a position where the arm side link, the mounting bracket, or the like does not interfere with the shock absorber and can maintain a predetermined distance from the rear wheel”. Under restrictions, by devising the structure of the cross member and the mounting bracket, the length of the rear arm can be reasonably shortened and the wheelbase of the vehicle body can be shortened (the rear wheel position can be brought closer to the front wheel).

Further, in the prior art, when the mounting bracket is simply provided so as to project downward from the lower surface of the cross member and the position is shifted to the front of the vehicle body, the position of the mounting bracket moves to the front of the vehicle body. The length of 18 becomes short, the lever ratio of the link mechanism becomes small, and the buffering characteristic deteriorates. On the other hand, according to the present invention, the mounting bracket is inclined rearward with respect to the cross member, so that the position of the cross member is shifted forward, that is, the arm side link of the link mechanism is shortened. The problem could be solved and the above-mentioned deterioration of the buffer characteristic could be avoided.

If the mounting bracket is simply projected downward from the lower surface of the cross member, when the rear arm pivots largely downward, the lower end of the shock absorber cylinder interferes with the mounting bracket, while the rear arm pivots largely upward. At this time, the lower end of the shock absorber cylinder may interfere with the arm-side link, but the mounting bracket must be installed so as to incline backward from the lower surface of the cross member (the center line C ₁ of the mounting bracket should be the vertical center of the cross member). The above-mentioned interference can be avoided by inclining backward with respect to the line C ₂ so that the cross-sectional shape of the cross member and the mounting bracket is V-shaped.). In other words, since the mounting bracket is provided so as to be inclined backward from the lower surface of the cross member, it is possible to adopt the structure in which the mounting bracket is provided so as to project downward from the lower surface of the cross member in the above-mentioned conventional technique. be able to.

[Brief description of drawings]

FIG. 1 is a side view of a motorcycle to which the invention is applied, and FIG.
1 is an enlarged view of a main part of FIG. 1, FIG. 3 is a sectional view taken along line III-III of FIG. 2, and FIG. 4 is a perspective view of a mounting bracket and a cross member. 11 …… Rear arm, 11a …… Arm part, 12 …… Link mechanism, 13 …… Shock absorber, 17 …… Body side link, 18 …… Arm side link, 22 …… Mounting bracket, 25 …… Cross member.

Claims (1)

[Claims] 1. A lower arm of a shock absorber, wherein a rear wheel is supported by a rear arm composed of a pair of arm portions connected to each other by a cross member, the rear arm is pivotally supported on a vehicle body, and a link mechanism is arranged below the rear arm. Through the pair of left and right arm parts, and project below the rear arm,
In a motorcycle in which the lower end of the shock absorber is connected to the above link mechanism, a rear arm support link mounting bracket is integrally provided on the lower surface of the cross member welded to the side surface of the rear arm so as to project downward when the cross member is molded. Connect the arm side links of the link mechanism, and tilt the center line C ₁ of the mounting bracket rearward with respect to the vertical center line C ₂ of the cross member so that the cross-sectional shape of the cross member and the mounting bracket is reduced. A rear arm support link mounting mechanism for a motorcycle, which is formed in a V shape so that the V-shaped inclination is substantially along the outer periphery of the rear wheel.