JP3417698B2 - Axle bracket mounting structure for front fork - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork axle bracket mounting structure.

[0002]

2. Description of the Related Art Generally, in a front fork 10 of a motorcycle, an inner tube 12 is slidably fitted in an outer tube 11 and an axle bracket 13 is attached to a lower end portion of the outer tube 11, as shown in FIG. The axle 16 is installed and configured to be capable of holding an axle 16 that rotatably supports a wheel 15 in an axle hole 14 of the axle bracket 13. The inner tube 12 is fixedly held by the upper bracket 17 and the under bracket 18, and via the upper bracket 17 and the under bracket 18,
The front fork 10 is swingably supported by the vehicle body 19.

The axle bracket 13 is shown in FIG.
The outer tube 11 according to the invention described in JP-A-63-34290
There is one in which the female screw portion 21 of the axle bracket 13 is screwed and attached to the male screw portion 20 formed on the outer periphery of the base end portion of the. In this mounted state, the base end surface 22 of the outer tube 11 abuts the bottom surface 23 of the axle bracket 13, and the vehicle bracket 13 is tightened with a constant torque.

[0004]

By the way, in the front fork 10 shown in FIG. 5, bending loads F in opposite directions from the axle 16 to the axle hole 14 of the axle bracket 13 and from the under bracket 18 to the inner tube 12.
₁ works. Therefore, bending loads F _{1 in} opposite directions are similarly applied to the outer tube 11 from the axle bracket 13 and the inner tube 12.

As described above, since the female screw portion 21 of the axle bracket 13 is screwed into the male screw portion 20 of the outer tube 11, the axle bracket 13 and the outer tube 11 are formed.
In the lap region of, there is at least a fitting gap t between the inner peripheral surface of the axle bracket 13 and the outer peripheral surface of the outer tube 11 so that the axle bracket 13 and the outer tube 11 can rotate relative to each other around the axis. Therefore, due to the action of the bending load F ₁ , the outer tube 11 is
As indicated by the arrow A, the vehicle body 19 swings in the front-rear direction.

On the other hand, as shown in FIG. 5, a caliper arm 24 is integrally formed on the axle bracket 13, and a brake caliper 25 is installed on the axle bracket 13.
The brake caliper 25 holds the disc brake 26 that rotates integrally with the axle 15 to brake the wheel 15. Therefore, the pulling force F ₂ in the clockwise direction acts on the caliper arm 24 during this braking, and the restoring force F _{3 in the} counterclockwise direction acts on the caliper arm 24 during the non-braking. As a result, a bending moment centering on the wheel 15 acts on the axle bracket 13, and the tensile force F is applied.
_The bending load is ₂ and the restoring force F ₃ . At this time, in the case where the brake caliper 25 is arranged only on one of the left and right front forks 10, a torsion torque also acts on the axle brackets 13 of both front forks 10 via the axle 16.

The pulling force F ₂ during braking and the restoring force F ₃ during non-braking have a fitting gap t in the lap region between the outer tube 11 and the axle bracket 13, so that the axle bracket 13 is stationary. Considering that, as in the bending load F ₁ , the outer tube 11 is swung in the front-rear direction A of the vehicle body 19.

When the oscillating motion based on the bending load F ₁ and the oscillating motion based on the tensile force F ₂ and the restoring force F ₃ occur, the base end face 22 of the outer tube 11 abuts the bottom face 23 of the axle bracket 13. Because it is, outer tube 1
In the wrap region between the outer tube 11 and the axle bracket 13, the base end surface 22 side portion of the outer tube 11 is restrained by the abutment and does not move toward and away from the bottom surface 23 side portion of the axle bracket 13, but the base portion of the outer tube 11 does not move. Since the portion away from the end face 22 does not have the above-mentioned constraint, it moves toward and away from the axle bracket 13. This outer tube 11
The contacting / separating motion of A becomes larger as it moves away from the base end face 22.

As a result, especially when the outer tube 11 is made of a light metal such as aluminum, the outer tube 1
In Fig. 1, stress concentrates on a portion X away from the base end surface 22 of the male screw portion 20, which is a sudden change in shape, and creep rupture occurs at this portion X over time, which may damage the outer tube 11. There is

The present invention has been made in consideration of the above circumstances, and can improve the strength of the wheel-side tube on which the axle bracket is mounted and reduce the weight of the axle of the front fork. It is intended to provide a bracket mounting structure.

[0011]

According to a first aspect of the present invention, a vehicle body side tube is slidably fitted in a wheel side tube, and a male screw portion is formed on an outer peripheral surface of a base end portion of the wheel side tube. In the axle bracket mounting structure of the front fork in which the female screw portion of the axle bracket supporting the axle is screwed to the male screw portion, and the axle bracket is attached to the wheel side tube, the outer peripheral surface of the wheel side tube is A stopper portion is formed on the vehicle body side tube side of the male thread portion, and a female thread portion of the axle bracket is screwed to a male thread portion of the wheel side tube,
The tip end portion of the axle bracket is configured to abut against the stopper portion. The invention of claim 2 is a contract
In the invention of claim 1, further, the above-mentioned axle bracket is
It consists of the bottom axle bracket, and
There is a gap between the end face and the bottom of the axle bracket.
It was made to exist. The invention of claim 3 is a claim
Further, in the invention of Item 1, the wheel side tube is the vehicle.
It is designed to extend through the axis bracket.
is there.

The invention of claim 4 is the invention of claims 1 to 3.
In addition, the stopper part is the axis of the wheel side tube.
It is configured with an abutment surface perpendicular to the
The tip of the shaft bracket is provided so that it can collide.
It

The invention of claim 5 is any of claims 1 to 3.
Further, in the above invention, the stopper portion is a wheel side tug.
On the outer peripheral surface of the tube, the diameter gradually increases toward the vehicle body side tube side
It is configured with a taper surface as an abutting surface.
The tip of the axle bracket is provided on the surface so that it can collide.
Of.

The invention of claim 6 is any of claims 1 to 5.
Further, in the above invention, an axle bra is attached to the stopper portion.
The protrusion is projected toward the racket side, and this protrusion is the above-mentioned axle.
It is crimped into the recess at the tip of the bracket so that it can be engaged.
It was scraped off.

[0015]

According to the invention described in claims 1 to 5 , there are the following actions. The stopper portion of the annular is formed in the vehicle <br/> side tube side of the male screw portion on the wheel side tube, the male
Since the tip of the axle bracket can be abutted against the stopper in the state where the internal thread of the axle bracket is screwed into the threaded portion, most of the bending load acting on the wheel side tube is It is transmitted to the axle bracket via the stopper portion of the wheel side tube, and a part thereof is transmitted to the portion on the base end side of the stopper portion of the wheel side tube. The proximal portion than the stopper portion of the wheel side tube, because it is constrained to the axle bracket through the stopper, a part of the bending load above this portion acts, and an axle bracket Rocking motion does not occur between. Therefore, stress concentration does not occur in the vicinity of the male screw portion located on the base end side of the stopper portion in the wheel side tube, and creep fracture does not occur in the vicinity of the male screw portion. As a result, the strength of the wheel side tube can be improved.

Since the axle bracket is generally manufactured to have a rigidity higher than that of the wheel side tube, creep failure does not occur in the vicinity of the female screw portion even by the action of the bending load.

Further, in the screwed state between the axle bracket and the wheel side tube, it is configured to distal portion of the axle bracket stopper portion of the wheel side tube may abut, <br/> by Uni wheel side of the above Since the strength of the tube has improved, that much
The wheel-side tube can be made thin, and the wheel-side tube can be made lightweight.

According to the invention described in claim 4, there is the following action. Since the convex portion of the wheel side tube is configured to be engageable with the concave portion of the axle bracket, the axle bracket can be prevented from rotating with respect to the wheel side tube.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. A. First Embodiment (FIGS. 1 and 2) FIG. 1 is a side view showing a front fork to which a first embodiment of an axle bracket mounting structure for a front fork according to the present invention is applied, in which a part thereof is shown in a sectional view. is there. Figure 2
It is sectional drawing which expands and shows a part of FIG. In the above-mentioned first embodiment, the same parts as those in the above-mentioned conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, a front fork 30 of a motorcycle has an inner tube 12 as a vehicle body side tube inside an outer tube 31 as a wheel side tube.
Is slidably disposed, and the axle bracket 13 is disposed at the base end portion of the outer tube 31.
3, the wheel 15 is rotatably supported via the axle 16, and the inner tube 12 is attached to the vehicle body 19 via the upper bracket 17 and the under bracket 18.
It is configured to be swingably supported by.

The outer tube 31 is formed by extruding or drawing a light alloy such as aluminum.
Further, the outer circumference is cut into a predetermined shape. Further, the vehicle bracket 13 is manufactured by casting aluminum.

Outer tube 31 and inner tube 1
A damper cylinder 32 is disposed in the second cylinder 2, and the base end of the damper cylinder 32 is fixed to the axle bracket 13. A coil spring (not shown) is provided between the damper cylinder 32 and the inner tube 12, and a piston (both not shown) having an expansion side damping mechanism and a compression side damping mechanism 33 are provided in the damper cylinder 32. And a partition member 34. By these coil springs and damping mechanism, the impact from the road surface is absorbed and the vibration of the front fork 10 is damped.

A male screw portion 35 is formed on the outer peripheral surface of the base end portion of the outer tube 31, as shown in FIG.
The male screw portion 35 is attached to the female screw portion 21 of the axle bracket 13.
Are screwed together, and the axle bracket 13 is attached to the outer tube 31.
Attached to.

Further, on the outer peripheral surface of the base end portion of the outer tube 31, a stopper portion 36 is integrally formed on the inner tube 12 side with respect to the male screw portion 35. This stopper portion 36 is
The outer tube 31 slightly protrudes from the outer peripheral surface and is formed in a ring shape over the entire outer peripheral surface. An abutting surface 38 that is perpendicular to the axis 37 of the outer tube 31 is formed on the stopper portion 36.

With the male screw portion 35 of the outer tube 31 and the female screw portion 21 of the axle bracket 13 screwed together, the tip surface 39 of the axle bracket 13 abuts the abutment surface 38,
Positioned axially. The tip surface 39 and the abutting surface 38
In the abutting state of the
Is separated from the bottom surface 23 of the axle bracket 13. That is, there is a gap between the base end surface 40 of the outer tube 31 and the bottom surface of the vehicle bracket 13.

Further, at any position in the circumferential direction of the stopper portion 36, toward the tip surface 39 side of the axle bracket 13,
A caulking portion 41 as a convex portion is provided so as to project. The caulking portion 41 is caulked and engaged with a recess 42 formed in the tip surface 39 of the axle bracket 13,
Are stopped from rotating with respect to the outer tube 31.

According to the above embodiment, the outer tube 31
A stopper portion 36 is integrally formed by cutting on the inner tube 12 side with respect to the male screw portion 35.
Since the front end surface 39 of the axle bracket 13 can be abutted against the abutting surface 38 of the stopper portion 36 in a state where the female screw portion 21 of the axle bracket 13 is screwed to the shaft 5,
Bending load F ₁ , F ₂ , F acting on the outer tube 31
Most of ₃ is the stopper 3 of the outer tube 31.
It is transmitted to the axle bracket 13 via 6 and is partially transmitted to the portion 40A of the outer tube 31 closer to the base end face 40 than the stopper portion 36. In a region where the outer tube 31 and the axle bracket 13 overlap, a portion 40 on the base end face 40 side of the stopper portion 36 of the outer tube 31.
Since A is constrained to the tip surface 39 of the axle bracket 13 by the stopper portion 36, even if the bending loads F ₁ , F ₂ , and F ₃ act on this portion 40A as described above, the axle bracket 13 No rocking motion occurs between and. Therefore,
In this outer tube 31, stress concentration does not occur in the vicinity of the male screw portion 35 located in the portion 40A on the base end face 40 side of the stopper portion 36, and creep fracture does not occur in the vicinity of the male screw portion 35. As a result, this outer tube 31
The strength of can be improved.

Since the axle bracket 13 is generally manufactured to have a rigidity higher than that of the outer tube 31,
Creep failure does not occur in the vicinity of the internal thread 21 even by the action of the bending loads F ₁ , F ₂ , and F ₃ .

Further, in the abutting state of the axle bracket 13 and the wheel side tube 31, the distal end surface 39 of the axle bracket 13 is abutted against the stopper portion 36 of the wheel side tube 31, as described above. Since the strength of the outer tube 31 is improved, the outer tube 31 can be thinned accordingly, and the weight of the outer tube 31 can be reduced. Therefore, the unsprung load of the front fork 10 can be reduced.

Further, the caulked portion 41 of the outer tube 31
Is provided so as to be engageable with the recess 42 of the axle bracket 13, it is possible to prevent the axle bracket 13 from rotating with respect to the outer tube 31.

B. Second Embodiment (FIG. 3) FIG. 3 (A) is a sectional view corresponding to FIG. 2 showing a second embodiment of the front fork axle bracket mounting structure according to the present invention, and FIG. 3 (B). 3 is an enlarged cross-sectional view of a main part of FIG.

In the front fork 50 of this embodiment,
An inner tube 52 is slidably arranged in the outer tube 51, and the outer tube 51 extends through the axle bracket 53. Also in this front fork 50, a coil spring (not shown) arranged via the collar 54A between the outer tube 51 and the inner tube 52, and the damper cylinder 5
The impact from the road surface is absorbed by the extension side damping mechanism and the compression side damping mechanism arranged inside the front fork 50.
Vibration is suppressed.

A male screw portion 55 is formed on the outer peripheral surface of the base end portion of the outer tube 51, and a stopper portion 56 is integrally formed on the inner tube 52 side of the male screw portion 55. An abutment surface 58 perpendicular to the axis 57 of the outer tube 51 is formed on the stopper portion 56. On the other hand, a female screw portion 59 that can be screwed into the male screw portion 55 is formed on the inner peripheral surface of the axle bracket 53. With the female screw portion 59 screwed into the male screw portion 55, the tip end surface 60 of the axle bracket 53 is abutted against the stopper surface 56 of the stopper portion 56.
Is struck by.

Therefore, in this front fork 50 as well, the bending loads F ₁ , F acting on the outer tube 51 are applied.
Most of ₂ , F ₃ are abutting surfaces 58 of the stopper portion 56.
Is transmitted to the axle bracket 53, and a part of the outer tube 51 is transmitted to a portion 61A of the outer tube 51 closer to the base end face 61 than the stopper portion 56. However, in the region where the outer tube 51 and the axle bracket 53 overlap, the portion 6 of the outer tube 51 closer to the base end face 61 than the stopper portion 56.
1A is restrained by the front end surface 60 of the axle bracket 53 via the stopper portion 56 and no swinging motion is generated, so that stress is not concentrated near the male screw portion 50 provided in this portion 61A, and the outer tube 51 of the outer tube 51 is prevented. The strength can be improved, and the outer tube can be made thinner and the weight thereof can be reduced accordingly.

C. Third Embodiment (FIG. 4) FIG. 4 is a sectional view corresponding to FIG. 2, showing a third embodiment of the axle bracket mounting structure for a front fork according to the present invention.

In the front fork 70 of this embodiment,
An inner tube 72 is slidably arranged in the outer tube 71, and the outer tube 71 extends through the axle bracket 73. Also in this front fork 70, a coil spring installed between the outer tube 71 and the inner tube 72,
The impact from the road surface is absorbed by the extension side damping mechanism and the compression side damping mechanism 75 arranged in the damper cylinder 74, and the vibration of the front fork 70 is damped.

A male screw portion 76 is formed on the outer peripheral surface of the base end portion of the outer tube 71, and the male screw portion 76 is formed.
The stopper part 76 is integrally formed on the inner tube 72 side. The stopper portion 76 is provided on the outer tube 71.
A taper surface gradually increasing in diameter toward the inner tube 72 side is provided as an abutment surface 78 on the outer peripheral surface of the. On the other hand, a female screw portion 79 is engraved on the inner peripheral surface of the axle bracket 73,
This female screw portion 79 is used as the male screw portion 76 of the outer tube 71.
And the axle bracket 73 is screwed onto the outer tube 71.
Attached to. In this mounted state, the tip end tapered portion 80 of the axle bracket 73 abuts against the abutment surface 78.

Therefore, in this front fork 70 as well, the bending loads F ₁ , F acting on the outer tube 71 are applied.
Most of ₂ and F ₃ are abutting surfaces 78 of the stopper 77.
Is transmitted to the axle bracket 73, and a part thereof is transmitted to a portion 81A of the outer tube 71 closer to the tip surface 81 than the stopper portion 77. However, in the region where the outer tube 71 and the axle bracket 73 overlap, the portion 8 of the outer tube 71 closer to the tip surface 81 than the stopper portion 77.
1A is restrained by the tip taper portion 80 of the axle bracket 73 via the abutting surface 78, so that no swinging motion occurs, and stress does not concentrate near the male screw portion 76 provided in this portion 81A. The strength of the outer tube 71 can be improved. Furthermore, the outer tube 71 can be made thinner and lighter by that amount.

In each of the above embodiments, the stopper portion 36,
Although 56 and 77 are described as being formed in a ring shape around the outer tubes 31, 51 and 71, even if a plurality of stopper portions are installed on the outer circumference of these outer tubes 31, 51 and 71. good.

[0040]

As described above, according to the axle bracket mounting structure of the front fork according to the present invention, the strength of the wheel side tube on which the axle bracket is mounted can be improved and the weight thereof can be reduced. it can.

[Brief description of drawings]

FIG. 1 is a side view showing a part of a front fork to which a first embodiment of a front fork axle bracket mounting structure according to the present invention is applied, in a sectional view.

FIG. 2 is a cross-sectional view showing a part of FIG. 1 in an enlarged manner.

3 (A) is a sectional view corresponding to FIG. 2, showing a second embodiment of a front fork axle bracket mounting structure according to the present invention, and FIG. 3 (B) is a sectional view corresponding to FIG. It is a principal part expanded sectional view of A).

FIG. 4 is a sectional view corresponding to FIG. 2, showing a third embodiment of the front fork axle bracket mounting structure according to the present invention.

FIG. 5 is a side view showing a front portion of a motorcycle equipped with a front fork.

FIG. 6 is a sectional view showing a conventional axle bracket mounting structure for a front fork.

[Explanation of symbols]

12 Inner tube 13 axle bracket 21 Female thread 23 Bottom of axle bracket 30 front forks 31 Outer tube 35 Male thread 36 Stopper 37 Outer tube axis 38 Abutment surface 39 Tip surface of axle bracket 41 Caulking part 42 Axle bracket recess 50 front fork 51 Outer tube 52 Inner tube 53 axle bracket 55 Male thread 56 Stopper 57 Outer tube axis 58 Abutment surface 59 Female thread 60 Tip surface of axle bracket 70 front fork 71 Outer tube 71 Inner tube 73 axle bracket 76 Male thread 77 Stopper 78 Face to face 79 Female thread 80 Tapered end of axle bracket

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B62K 25/08 F16F 9/32 F16F 9/54

Claims (6)

(57) [Claims] 1. A vehicle body side tube is slidably fitted in a wheel side tube, a male thread portion is formed on a base end outer peripheral surface of the wheel side tube, and a female thread portion of an axle bracket for supporting an axle is the above. In an axle bracket mounting structure of a front fork screwed to a male screw portion to attach the axle bracket to the wheel side tube, a stopper portion on the vehicle body side tube side of the male screw portion is provided on an outer peripheral surface of the wheel side tube. Is formed, and the distal end portion of the axle bracket abuts against the stopper portion in a state where the female screw portion of the axle bracket is screwed into the male screw portion of the wheel side tube. Front fork axle bracket mounting structure. 2. The axle bracket above has a bottomed axle bracket.
The wheel side tube base end face and the car.
A gap exists between the bottom surface of the shaft bracket and the bottom surface of the shaft bracket.
1. A front fork axle bracket mounting structure according to 1. 3. The wheel side tube is attached to the axle bracket.
The front flap according to claim 1, wherein the front flap extends through the tongue.
Oak axle bracket mounting structure. 4. The stopper portion is provided with an abutment surface perpendicular to the axis of the wheel side tube, and the tip end portion of the axle bracket is abuttably provided on the abutment surface.
The axle bracket mounting structure for a front fork according to any one of 1 to 3 . 5. The stopper portion is provided with a tapered surface on the outer peripheral surface of the wheel side tube, the diameter of which gradually increases toward the vehicle body side tube, as an abutment surface, and the tip end portion of the axle bracket is attached to the abutment surface. Claim 1 provided so as to be able to collide .
3. A front fork axle bracket mounting structure according to any one of 3 above. The method according to claim 6, wherein said stopper portion, a convex portion is protruded toward the axle bracket side, claim 1, the convex portion is provided to be engageable caulked in the recess of the front end portion of the axle bracket 5. The front fork axle bracket mounting structure according to any one of to 5 .