JPH0534318Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an assembly structure of a rear fork for a motorcycle.

Prior art and its problems A rear fork for a motorcycle has a pair of left and right arm members, a horizontal connecting member that connects both arm members together, a pivot bearing member attached to the front ends of both arm members, and a rear fork attached to the rear ends of both arm members. It is formed with the attached axle bearing member as the main member. Typically, a rear fork is provided as an integrally welded assembly of steel tubes, steel plate members, or an integrally welded assembly of aluminum alloy castings, forgings, extrusions, or plates.

Aluminum alloy rear forks are advantageous in reducing the weight of the car body and unsprung load, and each component is appropriately hollow to reduce weight while ensuring strength and rigidity. . In this aluminum alloy rear fork, the front half, which receives a large load, that is, the horizontal connecting member,
It is advantageous in terms of strength to form the front end of the arm member having the pivot receiving member as an integral part by casting.

However, when the front half of the rear fork is made of an integral casting, a large mold is used, which impairs the flow of the molten metal, making it impossible to reduce the wall thickness and resulting in excessive weight. Further, even if the front half of the rear fork as an integral part is machined from the block, it is a large part, requires a large amount of work, and the product becomes expensive.

Means to Solve the Problems The present invention was devised against this technical background, and its purpose is to create a welded assembly structure for the rear fork that is advantageous in terms of strength while also reducing weight. It is in the point of providing.

The purpose of this is to connect the left and right front arms that extend toward the pivot shaft, which serves as the tilting fulcrum, in a motorcycle rear fork in which the lateral connecting member connects the left and right arm members together at a position distant from the swinging fulcrum at the front end. The member, the left and right rear arm members extending toward the rear axle, and the horizontal connecting member are integrally welded to each other to form this, and the side surface of the front arm member on the vehicle body center line side and the front surface of the horizontal connecting member and are continuous in a curved shape in plan view, and the weld line of the front arm member and the horizontal connection member is
This is achieved by creating a linear shape in plan view that expands outward from the curved surface toward the rear of the vehicle body.

Embodiment Hereinafter, an embodiment of the present invention shown in FIGS. 1 to 24 will be described.

FIG. 1 shows a motorcycle 10 as a left side view, and the body frame includes a head pipe 12.
and a main pipe 14 connected to the head pipe 12.
and down tube 1 connected to head pipe 12.
6, the down tube 16 and the main pipe 14
A center pillar 18 connected to the main pipe 14, a seat support pipe 20 connected to the main pipe 14, and a center pillar 1
8 and a backstay 22 connecting the seat support pipe 20 are formed as main frame members.

A pair of left and right protrusions 24 attached to the center pillar 18 near the connection with the backstay 22 include
A rear fork 36 is swingably supported via a pivot bolt 28. A shock absorber 34 (rear suspension) interposed between the vehicle body frame and the rear fork 36 has its upper end supported by a protrusion 26 attached to the main pipe 14, and is supported by links 30 and 32 connected to the rear fork 36. It is supported at its lower end.

The detailed shape of the rear fork 36 is shown in FIGS. 2 to 4. The rear fork 36 has a general shape including left and right arms 38, 40, and a horizontal connecting body 4.
It is formed as a generally H-shaped body consisting of two parts. The rear fork 36 is formed as a generally five-piece welded assembly, each of which may be formed as a single-piece or multi-piece integral welded assembly.

The five members are the left and right front arm members 4;
4, 62, left and right rear arm members 116, 132, and a horizontal connecting member 64. According to FIG. 3, the front arm member 44 and the horizontal connecting member 64 are joined at a welding line _W1 , the front arm member 62 and the horizontal connecting member 64 are joined at a welding line _W2 , and the rear arm member 116 and the horizontal connecting member 64 are joined at a welding line W2. The front arm member 44 and the horizontal connecting member 64 are joined together at a welding line _W3 , and the rear arm member 132 and the front arm member 62 and the horizontal connecting member 64 are joined together at a welding line _W4 . The side surfaces S ₁ and S 2 on the vehicle center line side of the front arm members 44 and ₆₂ and the front surface S ₃ of the horizontal connecting member 64 are connected in a curved shape in plan view, and the weld lines W ₁ and W ₂ are connected to the curved surface. It has a linear shape in plan view that expands outward from the surface toward the rear of the vehicle body.

Next, the front arm member 44, the rear arm member 116, and the horizontal connecting member 64 will be explained. However, the description of the front arm member 62 and the rear arm member 132 will be omitted because they are substantially symmetrical in left-right shape with the front arm member 44 and the rear arm member 116, respectively.

Regarding the front arm member 44 (Figs. 5 to 8)
(Figure): The front arm member 44 consists of a substantially cylindrical pivot bearing portion 46 and a main body 48 that is continuous with the pivot bearing portion 46. The main body 48 has a neck portion 50 connected to the pivot bearing portion 46 having a rectangular cross section, and the other portions having a U-shaped cross section that is open outward in the vehicle width direction. This U-shaped body has an upper wall 5.
2, a side wall 54, and a lower wall 56. Further, a U-shaped end surface 58 of the main body 48 is formed along the plane _S4 , and a groove 60 for welding is formed (FIGS. 5 and 8).

The hole 50a of the neck portion 50, which is a hollow body, is open toward the end face 58 side, and its depth h is sufficiently large and reaches the wall of the pivot bearing portion 46. This hole 50a is formed by cutting.

Regarding the horizontal connecting member 64 (FIGS. 9 to 1)
(Fig. 9): The horizontal connecting member 64 is a hollow body. Horizontal connection member 6
4 has upper and lower halves welded together, so the lower half 66 will be explained first, and then the upper half 98 will be explained.

-1 (FIGS. 9 to 14): As shown in FIG. 9, the lower half body 66 is formed as a breastplate-shaped body in plan view, and the center portion of the base wall 68 in the vehicle width direction swells upward. , thereby forming a groove space 70 oriented in the longitudinal direction of the vehicle body on the lower surface side.
Bottomed cylindrical bodies 72, 72 whose center lines are oriented left and right in the vehicle width direction are integrally formed with the base wall 68 in a form distributed to the left and right sides of the groove space 70. Holes 74, 74 are formed in the bottom walls of the bottomed cylindrical bodies 72, 72, and the links 3 are passed through the holes 74, 74.
Bolts for supporting 0 are attached, and the bolts and nuts can be tightened and fixed using the bottom wall.

Furthermore, a flange 76 is provided that extends from the base wall 68 and the bottomed cylindrical bodies 72, 72 in a direction along the center line of the bottomed cylindrical bodies 72, 72, and has a chevron-shaped upper side.

The base wall 68 stands up at the front and is formed as a front wall 78 , and includes an upper end surface 80 of the front wall 78 and a front end surface 8 extending from the left and right sides of the front wall 78 to the front side of the base wall 68 .
2 and 84 are formed as welding abutment surfaces provided with grooves (FIGS. 13 and 14).

Further, the base wall 68 rises at the rear portion to form a rear wall 86. The upper side of the rear wall 86 is shaped like a chevron at the center in the vehicle width direction, and extends upward from the left and right skirts of the chevron, and then extends outward in the vehicle width direction. This upper side is referred to as a chevron-shaped upper end surface 88 and a curved end surface 90 facing forward in the longitudinal direction of the vehicle body. Curved end surface 90
are the end faces of the portions of the rear wall 86 that protrude forward like eaves on the left and right sides in the vehicle width direction. A portion corresponding to the rear side of the projecting portion is formed into a curved rear end surface 92. A substantially symmetrical rear end surface 94 is formed below and apart from this rear end surface 92 (FIGS. 9 and 12).
These upper end surfaces 88, curved end surfaces 90, rear end surfaces 9
2. Both of the rear end surfaces 94 are welding abutment surfaces with grooves formed therein.

Furthermore, fitting pieces 96 having a U-shaped cross section and extending rearward in the longitudinal direction of the vehicle body are formed at the left and right outer ends of the rear wall 86, and are adapted to be fitted into the rear arm members 116, 132.

-2 (FIGS. 1 to 19): The upper half 98 is a member that forms the hollow horizontal connecting member 64 together with the lower half 66, and covers the upper surface of the lower half 66 and connects the peripheral and central portions thereof. The parts are welded together. The upper half body 98 is a shaped body that covers the upper surface of the lower half body 66 except for the fitting pieces 96 that are claw-shaped in plan view and protrude from the left and right rear portions of the lower half body 66, and its center portion is self-contained. It has a shape that bulges out on the top side. A linear slit 100 is formed by cutting this bulged portion in the left-right width direction at approximately the center of the width of the vehicle body in the longitudinal direction. The flange 76 of the lower half body 66 is applied to this slit 100 from the bottom side, and the slit 100
The upper half body 98 and the collar 76 are integrally welded together at the portion. Incidentally, an inclined groove 102 is formed around the slit 100 (see FIG. 15,
6, 19).

The front portion of the upper half body 98 extends downward to form a front wall 104.
The lower end surface 106 is formed as a butting surface for welding with a groove provided with the L-shaped front end surfaces 108 located on the left and right sides (first
5 to 17, and 19).

Further, the rear part of the upper half body 98 extends downward and is formed as a rear wall 110, and the lower end surface 112 thereof is
Together with the curved rear end surfaces 114 located on the left and right, it is formed as a butt surface for welding with a groove (FIGS. 15, 18, and 19).

-3: The lower half body 66 and the upper half body 98 having such shapes are assembled by attaching the upper half body 98 to the lower half body 66 in a manner that covers the upper surface of the lower half body 66, and welding the butted end surfaces. They are integrated by joining. The combinations of the butted end faces of the lower half body 66 and the upper half body 98 and other welded parts are as follows.

Upper end surface 80 - Lower end surface 106 Upper end surface 80 - Lower end surface 112 Curved end surface 90 - Rear end surface 114 Tsuba 76 - Slit 100 About the rear arm member 116 (FIGS. 20 to 22): The rear arm member 116 has upper and lower ends. half of 118,1
20 are welded together, and the weld line is indicated by weld line _W5 . The rear arm member 116 is A
The half part has a U-shaped cross section that is open toward the center of the vehicle body in the vehicle width direction, and the B half part has a rectangular cross section. a front end surface 112 of the rear arm member 116;
The upper and lower cross sections 124 and 126 of the A half and the curved end surface 128 located at the boundary between the A half and the B half are welding end surfaces.

Further, a circular window 130 is formed in the side wall of the rear arm member 116 in the A half, and the circular window 13
The bottomed cylindrical body 72 of the lower half body 66 is fitted into the lower half body 66 . According to this fitting relationship, after assembling the rear fork 36, a tool is inserted into the bottomed cylindrical bodies 72, 72, and a bolt for holding the link 30 is inserted.
The nut can be attached and detached.

The shapes of the front arm member 44, the horizontal connecting member 64, and the rear arm member 116 have been described above. To combine these members, the U-shaped end surface 58 of the front arm member 44 is pressed against the abutting surface of the horizontal connecting member 64, in which the front end surfaces 82, 84 and the front end surface 108 are continuously formed into a U-shape. The front arm member 44 and the horizontal connecting member 64 are welded together, and the A half of the U-shaped cross section of the rear arm member 116 becomes the side surface of the integrated front arm member 44 and the horizontal connecting member 64. A claw-shaped fitting piece 96 of the lower half body 66 in plan view is fitted into the rectangular cross section of the rear arm member 116 in a manner that covers the curved end surface 128 of the rear arm member 116 and the rear end surface 92 which are butted together.
At the same time, the front end surface 122 and the side end surface 1 are welded.
24 and 126 parts are the front arm member 44 and the horizontal connecting member 6
4 is welded and integrated. Front arm member 6
2. The rear arm member 132 is also welded and joined in the same manner as the front arm member 44 and the rear arm member 116.

In addition, at the rear ends of the rear arm members 116, 132,
The axle bearing members 134 and 136 are welded together.

Advantages of adopting the rear fork 36 having such an assembly structure are as follows.

The welding line W ₁ of the front arm members 44, 62 and the horizontal connecting member 64 is defined as the continuous plane S ₁ , S ₂ , S ₃ of the front arm members 44, 62 and the horizontal connecting member 64 in a curved shape in plan view.
It has a linear shape in plan view that expands outward toward the rear of the vehicle body, and the position of this weld line W ₁ is a position where the entire length of the U-shaped weld line can be ensured sufficiently large, and the weld line W ₁ Coupled with the fact that the arm 3 of the rear fork 36 is tilted in a plan view with respect to the center line of the vehicle body in the vehicle width direction, the arm 3 of the rear fork 36
It has an advantageous joining structure that can disperse stress against bending loads acting on the parts 8 and 40.

The lower half 66 of the horizontal connecting member 64 is connected to its base wall 6
8 is formed with a groove space 70 oriented in the front-rear direction of the vehicle body, so it has high rigidity against bending moments acting in the front-rear direction, and is oriented in the vehicle width direction (horizontal direction). Since the collar 76 welded to the body 98 and the bottomed cylindrical bodies 72, 72 are integrally formed with the body 98, the bending moment acting in the vehicle width direction and the horizontal connecting member 64 parallel to the vehicle body centerline are High rigidity against torsional moments around the centerline.

When the vehicle is running, a large load acting on the lower half body 66 due to the connection with the shock absorber 34 via the links 30 and 31 is transmitted to the center portion of the upper half body 98 via the collar 76 (FIG. 24). This structure is advantageous in reducing the burden on the lower half body 66 and reducing the overall weight of the horizontal connecting member 64, which is a hollow body.

Since the front arm member 44 is formed as a separate item from the lateral connecting member 64, the hole 50 in the neck portion 50
When removing a by machining, the rear (end surface 5
There are no obstructive parts on the 8th side), making it easy to process.
The depth h of the hole 50a can be made sufficiently large, and the weight of the front arm member 44 can be reduced as much as possible.

Front arm members 44, 62, rear arm member 116,
132 is formed as a hollow body, and the horizontal connecting member 64
Since the rear fork 36 is formed as a hollow body consisting of the lower half body 66 and the upper half body 98 and welded together, the rear fork 36 is sufficiently light in weight.

When the lower half body 66 and the upper half body 98 are joined together to form a hollow body, it is possible to join the lower half body 66 and the upper half body 98 using a plurality of pieces at the center of the hollow body. It is possible, but compared to that case,
The collar 76 of the lower half body 66 is inserted into the slit 1 of the upper half body 98.
00 and welding along a single line is efficient (reducing welding man-hours), and the relationship between the collar 76 and the slit 100 facilitates positioning of the upper half 98 with respect to the lower half 66. .

Effects of the invention As is clear from the above explanation, this is a rear fork for a motorcycle in which the horizontal connecting member connects the left and right arm members together at a position distant from the swinging fulcrum at the front end. The left and right front arm members that extend toward the pivot shaft, the left and right rear arm members that extend toward the rear axle, and the horizontal connecting member are integrally welded to each other to form the front arm members. The side surface on the side of the vehicle body center line and the front surface of the horizontal connecting member are connected in a curved shape in plan view, and the welding line between the front arm member and the horizontal connecting member is a straight line in plan view that expands outward from the curved surface toward the rear of the vehicle body. A shaped rear fork was proposed.

In this rear fork, the side surface of the front arm member on the side of the vehicle center line and the front surface of the lateral connecting member are connected in a curved shape in plan view, and the weld line between the front arm member and the lateral connecting member is directed from the curved surface toward the rear of the vehicle body. Since it has a linear shape in plan view that expands outward, it is possible to secure a sufficiently large weld line between the front arm member and the horizontal connecting member, and the weld line is inclined with respect to the direction of the bending load acting on the arm member. Coupled with this, the rear fork has a highly rigid structure capable of dispersing stress against bending loads.

In addition, the cutting of the weight by machining the front arm member,
This can be done independently of the transverse connecting members,
Since there are no members that obstruct the cutting process, the front arm member can be made sufficiently thin and lightweight.

[Brief explanation of drawings]

Fig. 1 is a side view of a motorcycle that employs a rear fork according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of the rear fork, Fig. 3 is a plan view of the rear fork, and Fig. 4 is the - line thereof. 5 is a plan view showing the left front arm member of the rear fork, FIGS. 6 and 7 are views taken along the - line and - line in FIG. 5, respectively, and FIG. 8 is a plan view showing the left front arm member of the rear fork. 9 is a plan view of the lower half of the rear fork that constitutes the horizontal connecting member, and FIG.
Figures 1 and 12 are - lines in Figure 9,
- line, - line arrow view, Fig. 13, 1st
Figure 4 is the - line in Figure 9, respectively.
- A line sectional view, FIG. 15 is a plan view of the upper half body integrally welded to the lower half body to form a horizontal connecting member, and FIGS. 16, 17, and 18 are respectively the same as those in FIG. - line, -
19 is a sectional view taken along the line - in FIG. 15, FIG. 20 is a plan view of the left rear arm member integrally welded to the front arm member and the horizontal connecting member, and FIG. Figure 22 is the - line in Figure 20, -
23 is a sectional view taken along the line -- in FIG. 3, and FIG. 24 is a schematic side view showing the link connection relationship between the rear fork and the shock absorber. 10...Motorcycle, 12...Head pipe,
14...Main pipe, 16...Down tube, 1
8...Center pillar, 20...Seat support pipe, 22...Back stay, 24...Protrusion piece, 26
... Protrusion, 28 ... Pivot bolt, 30 ...
Link, 32...Link, 34...Buffer device, 3
6... rear oak, 38... arm, 40... arm,
42... Lateral connecting body, 44... Front arm member, 46...
... Pivot bearing part, 48 ... Main body, 50 ... Neck section, 52 ... Upper wall, 54 ... Side wall, 56 ... Lower wall, 58 ... End surface, 60 ... Groove, 62 ... Front arm member , 64... Horizontal connection member, 66... Lower half body,
68... Base wall, 70... Groove space, 72... Bottomed cylindrical body, 74... Hole, 76... Flange, 78... Front wall,
80... Upper end surface, 82... Front end surface, 84... Front end surface, 86... Rear wall, 88... Upper end surface, 90... Curved end surface, 92... Rear end surface, 94... Rear end surface, 96
... Fitting piece, 98 ... Upper half, 100 ... Slit, 102 ... Bevel, 104 ... Front wall, 106 ...
... lower end surface, 108 ... front end surface, 110 ... rear wall,
112...lower end surface, 114...rear end surface, 116...
... Rear arm member, 118 ... Upper half body, 120 ... Lower half body, 122 ... Front end surface, 124 ... Lateral end surface, 1
26... Lateral end surface, 128... Curved end surface, 130...
...Round window, 132...Rear arm member, 134...Axle bearing member, 136...Axle bearing member, RW...
Rear wheel, W ₁ , W ₂ , W ₃ , W ₄ , W ₅ ... welding line.

Claims (1)

[Scope of Claim for Utility Model Registration] In a rear fork for a motorcycle in which the horizontal connecting member connects the left and right arm members together at a position distant from the swinging fulcrum at the front end, the pivot shaft side that is the swinging fulcrum The left and right front arm members extending toward the rear axle, the left and right rear arm members extending toward the rear axle, and a horizontal connecting member are integrally welded to each other, and the vehicle body centerline of the front arm members is The side surface and the front surface of the horizontal connecting member are connected in a curved shape in a plan view, and the weld line between the front arm member and the horizontal connecting member has a linear shape in a plan view that expands outward from the curved surface toward the rear of the vehicle body. A rear fork for motorcycles that is characterized by the following: