JP2549939Y2 - Rear swing arm of motorcycle - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention relates to the structure of a cantilevered rear swing arm constituting a rear wheel suspension of a motorcycle.

[Prior Art] As an example of a conventional rear swing arm, Japanese Patent Application Laid-Open
Japanese Patent Publication No. 184585 discloses a cantilevered rear swing arm that supports a rear wheel on one side of a rear end portion. In this device, a chain adjuster is housed in a cylindrical shaft-shaped holder provided at a rear end portion in a direction perpendicular to the rear end, and the rear wheel axle is supported through the chain adjuster. Driven sprockets for driving the chains are attached to each. Japanese Patent Application Laid-Open No. 58-183370 discloses a chain-driven automatic
A rear suspension of a wheel is shown, and a rear swing arm of the rear suspension arm has a pair of left and right pipe members arranged in parallel up and down, and each rear end is welded to an axle holder arranged in the vehicle width direction, thereby connecting the axle holder. We support both ends.

[Problem to be Solved by the Invention] Since the above-mentioned cantilever type rear swing arm is required to have high rigidity, a thick member is inevitably used, and the width becomes wide in the vertical direction. As a result, the chain line also extends up and down, and the size of the driven sprocket is limited to a large diameter.

In addition, even with the double-supported structure in the latter known example, it is desired to further increase the torsional rigidity of the axle holder support portion in order to be able to cope with the vertical twist applied from the axle.

Accordingly, an object of the present invention is to increase the torsional rigidity of the axle holder support portion and to enable the use of a small-diameter driven sprocket.

[Means for Solving the Problems] In order to solve the above problems, the rear swing arm of the motorcycle according to the present invention has a front end portion swingably supported by a vehicle body and is provided at a rear end portion. A cantilevered rear swing arm of a motorcycle that rotatably supports an axle having a rear wheel mounted on one end and a sprocket for driving a chain mounted on the other end via a cylindrical shaft, the rear swing arm includes front and rear ends A main arm disposed substantially linearly between the sub-arms and a sub-arm disposed at least above or below the main arm with a space therebetween; the sub-arm has a front part fixed to the main arm and a rear part bent; The main shaft is supported by a truss structure formed at the rear part of the main / sub arm by fixing the main arm to the main shaft at the rear end of the main arm.

[Action of the Invention] Since the axes of the axle and the main and sub arms in the cylinder shaft are located away from each other, the torsional rigidity of the cylinder shaft is increased. For this reason, despite the cantilever swing arm, the width of the main arm in the vertical direction can be reduced, a driven sprocket having a relatively small diameter can be used, and the overall weight can be reduced.

[Embodiment] Figs. 1 to 4 show an embodiment, and Fig. 1 shows a side surface of a skeleton portion of a main part of a vehicle body of a motorcycle. Reference numeral 1 denotes a rear swing arm whose front end is pivotally mounted on a pivot 3 of the vehicle body frame 2. E is the engine, S is its drive sprocket, and C is the rear cushion. An axle holder 4 is welded to the rear end of the rear swing arm 1,
An axle 6 is supported via an eccentric chain adjuster 5 supported inside. A rear wheel 7 is supported at one end of the axle 6, and a driven sprocket 8 is supported at the other end. Reference numeral 9 denotes a chain wound between the driven sprocket 8 and the drive sprocket S.

FIG. 2 shows an enlarged side view of the rear swing arm 1, and FIG. 3 shows a plan view thereof. The rear swing arm 1 has a substantially P-shape in plan view, and is substantially straight to the left of the vehicle body between the front and rear ends. The main arm 10 is provided with a sub-arm 11 which is disposed above the main arm 10 in a substantially same shape with an interval.

The front right side surface of the main arm 10 is welded to a cross portion 13 which protrudes upward in a box shape around a hole 12 through which the rear cushion C passes.

The front portion of the cross portion 13 forms a branch arm 14 which extends around the hole 12 and extends substantially in parallel with the front end side of the main arm 10. A pivot shaft is provided at each front end of the main arm 10 and the branch arm 14. Holder 15 is welded.

An intermediate portion 16 of the main arm 10 is curved outward to avoid a rear wheel, and an axle holder 4 disposed in a vehicle width direction is welded to a rear end portion. The axle holder 4 corresponds to the cylinder shaft of the present application.

The main arm 10 has a diameter much smaller than that of the conventional cantilever type, and the width in the vertical direction is particularly narrow.

The auxiliary arm 11 is a member of substantially the same shape that extends rearward from the rear portion of the cross portion 13 and extends so as to substantially overlap the intermediate portion 16 and the like of the main arm 10 in plan view (FIG. 3). Cross section
13 welded to the left side of the rear, and the middle part 18 and the main arm
A space 19 through which the chain 9 passes is formed between the intermediate portion 16 and the intermediate portion 16.

The rear end 20 of the sub arm 11 is bent obliquely downward and is welded to the upper surface of the axle holder 4. This weld is located just above the center point O of the axle holder 4 (FIG. 3).

A reinforcing plate 21 is provided behind the cross portion 13 between the main arm 10 and the sub arm 11 and in front of the space 19.

As shown in FIG. 2, a truss structure is formed around the space 19 at the rear of the main and sub arms 10, 11, and the axle holder 4 is supported by the truss structure. Incidentally, an axial line of the axle holder 4 near the portion of L ₁ and L ₂ each main and sub arms 10 and 11, both of which intersect at the rear and near the central point O of the axle holder 4.

The axle holder 4 is cut at one location on the circumference, and provided with bolt seat portions 22 and 23 for split fastening, and the both are fastened with bolts 24.

The chain adjuster 5 penetrates and supports the axle 6 at an eccentric position, and adjusts the front-rear position of the axle 6 by rolling in the axle holder 4. When the bolt 24 is tightened, the internal chain adjuster 5 is fixed so as not to roll, and when loosened, the chain adjuster 5 becomes rollable.

Next, the operation of the present embodiment will be described. As shown in FIG. 2, the rear swing arm 1 has an upper and lower dual structure of main and auxiliary arms 10 and 11, and supports the axle holder 4 by a truss structure at the rear. Therefore, the rear swing arm 1
As shown in FIG. 4, which is a diagram schematically showing the rear end of the axle holder 4 from the rear, even if the axle 6 twists the axle holder 4 in the vertical direction, the rigidity against the twist increases.

In addition, as is apparent from FIG. 2, the main arm 10 and the sub arm 11 are fixed to the axle holder 4 while being separated. For this reason, the torsional force is applied to the center point O of the axle holder 4 via the wheels 7.
It will act on the axle 6 located in the vicinity, but the main arm 10
Axis L ₁ of is located below the axle 6, the axis L ₂ of the sub-arm 11
Will be located above the axle 6. Therefore, since the main arm 10 and the sub arm 11 support the axle 6 at a position separated from each other, the rigidity against the torsional force can be extremely increased. Therefore, the width of the main arm 10 in the vertical direction can be made relatively small while maintaining the rigidity of the rear swing arm 1 at a predetermined value, so that the vertical width of the chain 9 can also be made small. As a result, the diameter of the driven sprocket 8 can be reduced. Becomes possible.

Moreover, the overall weight can be reduced by increasing the rigidity of the rear swing arm 1.

[Effects of the Invention] The rear swing arm according to the present invention includes a main arm arranged substantially linearly between the front and rear ends thereof, and a sub-arm arranged at least above or below the main arm with an interval therebetween. The auxiliary arm has a front portion fixed to the main arm and a rear portion bent to be fixed on the cylinder shaft fixed to the rear end of the main arm in a state separated from the main arm, so that the sub arm is attached to the rear portion of the main arm. The cylindrical shaft was supported by the formed truss structure. Therefore, since the axis of the axle and the axis of the main / sub arm in the cylinder shaft are located apart from each other, the torsional rigidity of the cylinder shaft is increased. For this reason, despite the cantilever swing arm, the width of the main arm in the vertical direction can be reduced, and a relatively small-diameter driven sprocket can be used. Moreover, the overall weight can be reduced.

[Brief description of the drawings]

1 to 4 show an embodiment, FIG. 1 is a side view of a main part of a motorcycle to which the present invention is applied, FIG. 2 is an enlarged side view of a rear swing arm, and FIG. FIG. 4 is a plan view, and FIG. (Description of Signs) 1 ... Rear swing arm, 4 ... Axle holder (cylinder shaft), 6 ... Axle, 7 ... Rear wheel, 8 ... Driven sprocket, 9 ... Chain, 10 ... Main arm, 11 …… Secondary arm.

Claims (1)

(57) [Scope of request for utility model registration] An axle having a front end portion swingably supported by a vehicle body and a rear wheel attached to one end and a chain drive sprocket attached to the other end via a cylindrical shaft provided at a rear end portion. In a cantilever type rear swing arm of a motorcycle which is rotatably supported, the rear swing arm has a main arm disposed substantially linearly between front and rear ends, and a space between at least one of upper and lower sides of the main arm. A sub-arm provided, the sub-arm having a front portion fixed to the main arm, a rear portion bent, and fixed to the cylinder arm fixed to the rear end of the main arm by being separated from the main arm and fixed thereto. A rear swing arm for a motorcycle, wherein the cylindrical shaft is supported by a truss structure formed at a rear portion of the main and sub arms.