JPH05246373A - Tapered swing arm for motorcycle - Google Patents

Abstract

PURPOSE:To form the tapered swing arm of a motorcycle of plate material in such a way that the length of weld parts need not be long. CONSTITUTION:The arm parts 13 of a swing arm 6 are formed of plate material. Rear tapered parts 10b are formed into angular pipe shape by bending, and the plate ends are connected by one longitudinal weld part. Front tapered parts 10a are vertically provided with inward flanges 10a1, and both ends of a cross member 14 are overlapped and welded at weld parts W2, W3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing arm for swingably supporting a rear wheel of a motorcycle, the swing arm having a tapered portion at the front and rear.

[0002]

2. Description of the Related Art In order to reduce the weight of a swing arm, the swing arm has a hollow body, and the dimension near the intermediate portion of the arm where the shock absorber is connected is maximized, and the dimension is reduced from here to the front end and the rear end. The shape is known, for example, from Japanese Patent Laid-Open No. 3-164390. However, this type of swing arm is difficult to process because it is necessary to form tapered front and rear taper parts in one member, and for example, the one disclosed in the above publication is bulged by pipe processing. The taper is formed in the front and rear, and when such a processing means is used, the equipment cost is high and the processing efficiency is low. Further, a means for welding two plate materials that are bent in a U-shape and abutting each other to form a square tube is conceivable.
Not only is it not suitable for aluminum alloy, which requires two welding lines and is expensive to weld, the number of jigs and the number of steps are large because two weldings are required, and the welding line is easily visible on the outer surface of the product. However, there is an inconvenience such as poor appearance.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a swing arm which has a small number of welded parts and a short welded length.

[0004]

Means for Solving the Problems According to the present invention, the means for solving the above problems is a motorcycle including a pair of hollow arm portions having a tapered front taper portion and a rear taper portion and a cross member connecting both the arm portions. In the tapered swing arm for a vehicle, the front taper portion and the rear taper portion of the arm portion have one continuous wall, and the front taper portion is continuously provided with a flange bent from the continuous wall toward the center of the vehicle body. Is provided with a wall portion bent from the continuous wall toward the center of the vehicle body and welded in a tubular shape, and a cross member is welded from the flange to the front portion of the rear taper portion.

[0005]

Since the above means is provided, a hollow taper swing arm is constituted by the arm and the cross member, and by forming the taper, substantially uniform stress is generated in each part, so that the weight can be reduced. Further, by providing the above-mentioned means, the welded portion is formed of the outer edge of the cross member and the rear tapered portion.
Only the mating part of the book, and the number and length of welded parts are small.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 9, reference numeral 1 is a frame of a motorcycle using a swing arm of the present invention, which includes a main frame 2, a rear frame 3 and a pivot plate 4, and a swing arm 6 is swingably connected by a pivot 5. The swing arm 6 has a maximum vertical portion 6max in the middle portion, and a front taper portion 6a and a rear taper portion 6b whose heights are gradually reduced from the portion are formed, and a buffer member 7 is provided between the maximum portion max and the rear frame. And the rear wheel WR in the mounting hole 8 at the rear end.
Is installed.

In FIG. 1, reference numeral 9 is a plate material that has been cut to form an arm portion that occupies the main part of the swing arm 6. The continuous wall 10 having a tapered front side wall 10a and a rear side wall 10b serves as a reference, and the front side wall is referred to. Flanges 10a ₁ , 1 above and below 10a
0a ₂ are continuously provided, and the upper wall 10b ₁ is provided above and below the rear side wall 10b.
And the lower wall 10b ₂ are connected in series, and the inner wall 10 is attached to the upper wall 10b _1.
b ₃ and the welding piece 10 b ₄ are successively connected.

The boundary line of each part is a bending line. The arm part used on the left side of the swing arm is bent so that the line is outside, and the arm part used on the left side is bent so that the line is inside. This is preferable because the welding line is on the lower side.

The plate material 9 is processed in the order shown in FIG. First, the lower plate 10b ₂ and the welding piece 10b ₄ are bent from the flat plate material 9 of FIG. 2A in FIG. 2B, U-shaped bending is applied in FIG. 2C, and jog processing is applied in FIG. In step e), the joggled portion is welded at the welded portion W ₁ to form the rear taper portion 6b. Then, in (f), bending is performed to form the bent portion 12, and in (g), the flanges 10a ₁ and 10a ₂ are bent to form the arm portion 13. 3 and 4 show the first embodiment,
In the figure, the swing arm 6 includes a pair of arm portions 13
Are formed by being coupled with the cross member 14 and the pivot bearing 15. Cross member 14 is 1 up and down
U-shaped deep cuts and shallow cuts are formed in the front and rear of the pair of cross plates 16 and 17, and U-shaped curved end plates 18 and 19 are welded so as to close the cuts to attach a shock absorber to the upper surface. Bracket 20 is welded. The outer portion of the cross member 14 is welded to the arm portion 13. That is, the flange 10a ₁ of the arm portion 13 is coupled by welding portions W ₃ of the welding portion W ₂ similar weld portion of the lower surface, and an inner wall 10b ₃ of the upper wall 10b _1. Further, the pivot bearing 15 is joined at the contact portion W ₄ .

As is apparent from the above description, the only welded portion for forming the arm portion 13 in this embodiment is W ₁ , and the other welded portions W _{2 to} W ₄ are for fixing cross members and the like. Although indispensable, each weld W _{2 to} W ₄
Cooperates with the flanges 10a ₁ , 10a _2, etc.
Helps to form 3.

Next, FIG. 5 and subsequent figures show a second embodiment. In the swing arm 22 of this embodiment, the arm portion 23 is made of a plate material and the cross member 24 is a cast product. The arm portion 23 has a continuous wall 25 composed of a front taper portion 25a and a rear taper portion 25b, and a reinforcing push-out portion 25 is provided on the continuous wall 25.
c is formed. The main portion of the arm portion 23 has a rectangular tubular shape bent from the continuous wall 25, and is joined by a single weld portion W ₅ provided at a seam at the inner center as shown in FIG. 7. A U-shaped flange 26 is vertically formed in the front portion, and a pin mounting work hole 27 for connecting the shock absorber is provided in the side surface.

As shown in FIG. 8, the cross member 24 has a top wall 28 and a bottom wall 29 which are recessed in an inverted trapezoidal shape.
A thick portion 30 is formed on the pair of inclined portions 28a, and a pin hole 31 is formed in the thick portion 30 to pivotally mount the shock absorber 7. Further, a pair of projecting portions 32 are provided on the front portion of the cross member 24, a pivot bearing 33 is provided thereon, and a rear wheel mounting portion 34 is welded on the rear portion thereof.

In this embodiment, the arm portion 23 and the cross member 24 are connected to each other by welding the upper and lower welding portions W ₆ , W ₇ along the opening of the arm portion 23, the rear end of the cross member 24 and the inner surface of the arm portion 23. Made by welding part W ₈ .

Also in this embodiment, the welding portion used only for the arm portion 23 is only W ₅ , and the other welding portions W _{6 to} W.
₇ is essential for fixing the cross member 24,
At the same time, it serves to form the front portion of the arm portion 23 together with the cross member 24.

[0015]

As described above, according to the present invention, since the weld portion for forming the swing arm is composed of one weld portion in the longitudinal direction and the weld portion for connecting the cross member, the weld portion as a whole. Has the advantage that the length is short and the process is simple. Especially when using aluminum alloy as the material,
Since the welding length is short, the cost reduction effect is excellent.

[Brief description of drawings]

FIG. 1 is a development view of a material for forming an arm portion of a first embodiment.

[Fig. 2] Process drawing of arm part

FIG. 3 is a plan view of a swing arm.

FIG. 4 Same as above, side view

FIG. 5 is a bottom view of the second embodiment.

FIG. 6 Same as above, side view

7 is a sectional view taken along line VII-VII of FIG.

8 is a sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a side view of the vehicle body

[Explanation of symbols]

6, 22 Swing arm 6a, 25a Front taper part 6b, 25b Rear taper part 10, 25
Continuous surface 10a _1, 10a _2, 26 flange 13, 23 arm portions 14, 29 cross member W ₁ to _W-8 weld

Claims (1)

[Claims] 1. A tapered swing arm for a motorcycle, comprising a pair of hollow arm portions having a tapered front taper portion and a rear taper portion, and a cross member for connecting the both arm portions, wherein a front taper portion of the arm portion is provided. The rear taper portion has one continuous wall, the front taper portion is continuously provided with a flange bent from the continuous wall toward the vehicle body center side, and the rear taper portion is bent from the continuous wall toward the vehicle body center side and is tubular. A taper swing arm for a motorcycle, comprising: a wall portion welded to a cross member, and a cross member welded from the flange to a front portion of a rear taper portion.