JPH101084A - Bicycle front fork connection structure - Google Patents

Abstract

(57) Abstract: A connecting body (22) is fixed to a lower part of a steering tube (21) so as to protrude rearward in a running direction of a bicycle, and is pivotally pivoted at a tip end of the connecting body (22) by a pivot shaft (23). A buffer coil spring 27 is arranged between the supported swinging body 24 and the steering tube 21. Then, the front bent portion of the rebound regulating projection 30 extending from the rocking body 24 is locked to the elastic rod 31, and the front fork 3 is fixed to the crown 25 of the rocking body 24. [Effect] Since the center of swing of the front fork is located behind the steering shaft, it is possible to set a large riding limit value for the front wheel with respect to obstacles, and to reduce the amount of change in the trail.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for connecting a front fork of a bicycle to a steering tube, and more particularly to a front fork connecting structure having a suspension function.

[0002]

2. Description of the Related Art FIG. 6 is a view showing a connection structure of a conventional suspension type front fork. In FIG. 6, reference numeral 1 denotes a head tube, and a steering shaft rotatably inserted into the head tube 1 has a connecting shaft 2.
The left and right front forks 3 are pivotally supported via the. A front wheel 4 is rotatably attached to the front end of each front fork 3.

Each front fork 3 has an extension portion 5 extending above the connecting shaft 2, and a swing type suspension mechanism 6 is provided at the upper end of the extension portion 5. The suspension mechanism 6 includes a substantially U-shaped connecting member 7 for connecting the left and right extending portions 5, a coil spring 8 for applying a pressing force to the connecting member 7, and a receiving member 9 for the coil spring 8.
, And the receiving member 9 is fixed to the headset 10 at the upper end of the head tube 1.

In this conventional connection structure, since the coil spring 8 presses the extension portions 5, 5 in the traveling direction of the bicycle, the front forks 3, 3 are rotated clockwise about the connection shaft 2, Therefore, the front wheel 4 elastically approaches the rear wheel side (not shown). Therefore, when the front wheel 4 rides on an obstacle while the bicycle is running, the reaction force causes the front fork 3 to rotate counterclockwise against the elastic force of the coil spring 8 to move the front wheel 4 upward. Therefore,
The front wheel 4 can get over the obstacle without moving the bicycle itself up and down even if it gets on an obstacle.

[0005]

FIG. 4 is an explanatory view of the limit of the riding height of the swing type suspension mechanism. In FIG. 4, the connection shaft 2 in the conventional connection structure described above is located at the position of the swing center "L1" on the steering shaft S, and the center of the axle of the front wheel 4 is located at the position "0". In such a positional relationship, assuming that a point at which a line segment M1 connecting the swing center L1 and the axle center 0 comes into contact with the outer periphery of the front wheel 4 is K1, an interval H1 between the contact point K1 and the ground is determined by an obstacle riding in the suspension mechanism. It becomes the limit value. Therefore, if the height of the obstacle is greater than H1, the reaction force is applied to the front wheels in a direction opposite to the traveling direction of the bicycle, so that the obstacle cannot be overcome. As described above, in the conventional connection structure, since the swing center L1 is located on the steering shaft S, there is a disadvantage that the height of the front wheel that can get over the obstacle is small.

FIG. 5 is an explanatory view of a trail showing operability of the handle. That is, assuming that the point at which the steering axis S contacts the ground is "P", and the point at which the vertical axis descends from the axle center 0 and contacts the ground is "A", the distance between the points P and A is referred to as a trail T, and the steering wheel is optimal. It is a value determined for each vehicle type so that it can be operated at a certain speed. Referring to FIG. 5, in the conventional connection structure described above, when the front wheel 4 rides on an obstacle having a height X, the front wheel 4 swings counterclockwise around the swing center L1 until the axle center 0 reaches the position 01. Displace. In this case, the point at which the steering axis S comes into contact with the obstacle instead of the ground is displaced to "P1", and the center of the axle is displaced to 01, so that the trail T1 at the time of riding is extremely small. For this reason, in the conventional connection structure, the handle operation becomes extremely light, and there is a possibility that the handle operation may be erroneously performed. Furthermore, in the conventional connection structure, since the suspension mechanism 6 is externally provided, the appearance is not preferable.

[0007]

The present invention has the following arrangement in order to solve such a problem. That is, the bicycle front fork connecting structure of the present invention includes a connecting member fixed to the steering tube and extending rearward in the traveling direction of the bicycle, and a front end of the connecting member which is pivotally supported so as to be able to approach and separate from the steering tube. Oscillating body, a crown portion provided on the oscillating body, to which a front fork is fixed, a cushioning elastic member arranged between the steering tube and the oscillating body, and separation of the oscillating body from the steering tube And a rebound regulating mechanism for regulating the distance.

<Explanation> The connecting body is attached to the steering tube so as to extend rearward in the running direction of the bicycle, and the rocking body is pivotally supported at the tip thereof. Therefore, the swing center of the front fork attached to the swing body is located behind the steering shaft in the traveling direction of the bicycle. Therefore, the point at which the line segment passing from the swing center to the center of the front wheel axle contacts the outer periphery of the front wheel is located at a height sufficiently higher than the ground, so that the riding limit value is large and the obstacle is a large obstacle. You can get over it.

When the center of swing of the front fork is located behind the steering shaft, the center of the front wheels is not displaced so much forward in the running direction of the bicycle even if the front wheels ride on obstacles and swing. The amount of change in the trail is small. Therefore, the operability of the handle can be maintained as it is. Furthermore, since the cushioning elastic member is located between the steering tube and the rocking body and does not appear directly outside, the appearance is excellent.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a front fork connecting structure according to the present invention, FIG. 2 is a plan view of the connecting structure, and FIG.
FIG. 2 is a front view showing a state in which the connection structure is attached to a bicycle. First, in FIG. 3, 1 indicates a head tube,
Left and right front forks 3 are connected to a steering tube inserted into the head tube via a front fork connecting structure 20 of the present invention. A front wheel 4 is rotatably attached to the front ends of the front forks 3.

[0011] The front fork connecting structure 20 of the present invention.
As shown in FIGS. 1 and 2, the vehicle includes a connecting body 22 fitted and fixed to the lower end of the steering tube 21. This connecting body 22 is inclined backward so as not to come into contact with the down tube 11 (see FIG. 3) and the mudguard 12, and extends downward in the rear direction in the running direction of the bicycle.

A swinging body 24 is pivotally supported at the tip of the connecting body 22 via a pivot shaft 23 so as to be able to swing vertically. The oscillating body 24 has a substantially U-shaped cross section so as to cover both side surfaces of the connecting body 22, and extends below the steering tube 21. On both sides of the distal end of the rocking body 24, substantially cylindrical crown portions 25, 25 are integrally formed. The left and right front forks 3,
3 is fitted and fixed at its upper end. A mounting hole 26 for mounting a brake device (not shown) is formed between the two crown portions 25 of the rocking body 24 as shown in FIG.

A buffer coil spring 27 is disposed between the tip of the rocking body 24 and the steering tube 21 along the vertical direction. The lower end of the coil spring 27 is engaged with a concave portion 4A formed to be inclined on the top surface of the tip end of the rocking body 24, and the upper end thereof is connected to the steering tube 21.
In contact with the receiving member 28 inside.

A hole 29 penetrating in the thickness direction is formed in the center of the connecting body 22, and a rebound regulating projection 30 extending upward from the center of the rocking body 24 enters the hole 29. The bent portion at the tip of the projection 30 is locked by a rubber elastic rod 31 disposed on the step 22 a formed in the hole 29. The hole 29, the projection 30, and the elastic rod 31 form a rebound restriction mechanism. In the front fork coupling structure having the above configuration,
When the front wheel 4 comes into contact with an obstacle, the rocking body 24 is
, And swings upward against the elastic force of the coil spring 27, so that the front wheel 4 moves upward and gets over an obstacle.

In the connection structure of the present invention, as shown in FIG. 4, the pivot shaft 23 is located behind the steering shaft S in the running direction of the bicycle, that is, at the position of the swing center "L2". The point where the line segment M2 connecting the swing center L2 and the axle center 0 contacts the outer periphery of the front wheel 4 is the "K2" position. Accordingly, the distance H2 between the contact point K2 and the ground is larger than the conventional distance H1, which indicates the limit of the height of obstacles. Therefore, even an obstacle having a large height can be overcome within the height range of H2. .

Further, as shown in FIG. 5, the pivot shaft 23 of the present invention is also at the position of the swing center "L2", so that when the wheel 4 rides on an obstacle having a height X, the front wheel 4 Swings about the swing center L2, and the axle center 0 is displaced to the position of “02”. That is, the amount of displacement of the center of the axle 0 forward in the traveling direction of the bicycle is small. In this case, the trail according to the present invention is T2 because the steering shaft S is in contact with the point P1 located at the height of X. Accordingly, the trail T2 according to the present invention is larger than the conventional trail T1, and has a value close to the preset trail T. Therefore, even if the front wheel 4 rides on the obstacle, the steering operation hardly changes.

Further, since the coil spring 27 is disposed between the steering tube 21 and the rocking body 24 and is not exposed to the outside, the appearance is excellent. Further, the coil spring 27 is arranged along the up-down direction, and
Since the concave portion 24A of the front wheel 4 is inclined, the front forks 3 and 3 can be expanded and contracted by directly receiving the vertical change, whereby the front wheel 4 can move up and down smoothly. Therefore,
When a coil spring having a small elasticity is selected as a coil spring, the front wheel 4 smoothly moves up and down even when traveling on a road having a good road condition, and therefore a bicycle having an inexpensive front fork connecting structure suitable for an urban area is provided. it can.

Further, when a braking force is applied to the bicycle by the braking device, since the pivot shaft 23 is located rearward of the steering shaft S, a turning force is applied to the front fork 3 clockwise in FIG. Therefore, even when sudden braking is applied, the vehicle body can be safely stopped without falling forward. In this case, since the bent portion of the projection 30 of the rebound restriction mechanism presses and deforms the elastic rod 31, the impact force of the brake can be absorbed.
In the above embodiment, a cylindrical elastic rubber may be used instead of the coil spring 27. Further, a cap may be attached to the hole 29 provided in the connecting body 22.

[Brief description of the drawings]

FIG. 1 is a sectional view of a bicycle front fork connecting structure according to the present invention.

FIG. 2 is a plan view of the connection structure.

FIG. 3 is a front view of the front wheel side of the bicycle having the connection structure.

FIG. 4 is an explanatory view of a riding height limit shown in relation to the present invention and a conventional structure.

FIG. 5 is an explanatory view of a trail shown in relation to the present invention and a conventional structure.

FIG. 6 is a front view of the front wheel side of a bicycle having a conventional front fork connection structure.

[Description of Signs] 3 Front fork 21 Steering tube 22 Connected body 23 Pivot shaft 24 Oscillator 25 Crown part 27 Cushion spring for cushion 30 Rebound regulating projection 31 Elastic rod

Claims (1)

[Claims] 1. A front fork connecting structure for a bicycle including a front fork supporting a front wheel and connected to a steering tube, comprising: a connecting member fixed to the steering tube and extending rearward in a running direction of the bicycle; An oscillating body pivotally supported by the distal end of the connecting body and swinging toward and away from the steering tube; a crown provided on the oscillating body, to which the front fork is fixed; A bicycle front fork connection structure, comprising: a shock-absorbing elastic member disposed between the rocking body and a rebound control mechanism for controlling a separation distance of the rocking body from the steering tube.