JPS6242870Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a steering front wheel suspension system for a vehicle such as an off-road tricycle using wide tires such as balloon tires.

The front wheel suspension system of off-road tricycles uses balloon tires, which have ultra-low pressure, so the flexibility of the tires is used to utilize the flexibility of the tires to function as a shock absorber, and the front fork that suspends and supports the front wheel has a shock absorbing function. It is composed of a rigid structure with no

By the way, when a motorcycle-type front fork equipped with a shock absorber with a buffering function is adopted to improve ride comfort, the left and right members of the front fork are extended upward in a straight line, and the upper and lower If the steering stem is used to support the head tube via the bridge, the top bridge will be extremely wide compared to a motorcycle because the tires are wide.

Therefore, the upper parts of the left and right shock absorbers, which have a wide gap in the width direction, are connected by a cast bottom bridge, and on top of this, the connecting members are made to stand upright on the part of the shock absorbers that is closer to the inside of the joint part by shortening the distance between the left and right sides. A structure in which the top bridge is horizontally connected between the upper ends of the members has been proposed, but since it is supported on the vehicle body side by a vertically installed connecting member in the middle inward from the shock absorber binding parts at both ends of the bottom bridge, Bending loads act on the bottom bridge, and it is necessary to increase its strength and rigidity to withstand this.Also, since the connection support part to the car body is far from the shock absorber connection part, where the bottom bridge load acts, the front fork The torsion of the bottom bridge caused by the caster angle needs to be supported only by the bottom bridge, and in this regard, it is also necessary to increase the strength and rigidity. The weight increases.

The present invention was made mainly to improve the above-mentioned problems when providing a buffer function to the front fork of a tricycle that uses balloon tires.
The purpose of this is to fix the bracket to the upper part of the left and right shock absorbers that support both ends of the axle at the bottom, connect the inside of the left and right brackets with a bottom bridge member made of pipe material, etc. A connecting member whose top is symmetrically inclined inward is connected and raised, and the upper ends of the members are connected by a top bridge member that is shorter in the width direction than the bottom bridge, which is lightweight, easy to manufacture, and has high strength. To provide a front wheel suspension system with excellent steering performance.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic side view of the tricycle, and FIG. 2 shows a plan view thereof.

Down tube 2 of frame 2 of auto tricycle 1
a The engine 3 is mounted at the rear, the fuel tank 4 is mounted above this, and the seat 5 is arranged behind this, and the transmission block 6 extending behind the engine 3 is mounted behind the seat 5. It is extended to the bottom,
Two rear wheels 7, 7 forming driving wheels are arranged on both sides,
The rear periphery of the seat 5 above the rear wheels 7, 7 is covered with a fender 8, and steps 9, 9 are provided projecting on the left and right sides of a frame bottom portion 2b extending rearward from the lower end of the down tube 2a. The rear wheels 7, 7 are constructed of large diameter and wide ultra-low pressure tires called balloon tires. A head tube 2c is fixed to the front end of the frame 2, and a front fork that suspends and supports a front wheel, which will be described next, is pivotally supported by the head tube 2c so as to be freely steerable.

The details of the front fork 10 are shown in detail from FIG. 3 onward, and the shock absorbers 11, 11, which constitute the main part of the front fork, are of a telescopic type, etc., which expand and contract in the axial direction to absorb and attenuate shock. The upper member 12 and the lower member 13 are each comprised of an upper member 12 and a lower member 13, which are fitted so as to be slidable in the axial direction. A boss portion 13a is formed at the lower part of the left and right lower members 13, 13, a front wheel axle 14 is installed between the boss portions 13a, and a hub 16a of the front wheel 16 is rotatably fitted around the axle 14 via a bearing 15. The front wheels 16 are constructed of very low pressure tires as before. Therefore, the width of the tire 16b is extremely wide compared to tires of motorcycles, etc., and the left and right shock absorbers 11, 11 are arranged parallel to each other with a sufficiently large gap in anticipation of deformation in the width direction of the tire. It will be done.

FIG. 4 shows a joint including the upper end of the upper member 12 of the shock absorber 11. The upper end of the upper member 12 is closed with a fork bolt 12a, and a spring 12 is placed below this.
b is interposed. A bracket 17 is fitted and fastened to the upper part of the upper member 12, and the bracket 17 has a vertically long cylindrical shape and is provided with a notch 18 extending radially outward from the lower part to the middle upper part, and the cross section therebetween is a notched circle C. Tightening flange portions 19, 1 are provided in the front and rear of the cutout portion 18.
9, and a slit 18 extending vertically and radially outward is formed between the flange portions 19, 19. A circular blind hole part 20 opening downward is provided at the middle upper part or lower part, and the upper part of the upper member 12 of the shock absorber of the front fork is fitted from below into this blind hole part 20, and the upper and lower parts of the flange parts 19, 19 are connected to each other. Bolts 21 are inserted into the mounting holes 19a and screw holes 19b provided concentrically in the
are inserted and screwed together, the front and rear flanges 19 are brought together and tightened, and the bracket 17 is fastened to the upper part of the upper member 12.

The brackets 17 that are fastened to the upper parts of the left and right upper members have a symmetrical shape, and circular boss portions 22 are provided inward in the width direction of the opposing tire at the intermediate portion thereof in a direction perpendicular to the axis of the brackets. The portion 22 is formed into a hollow cylindrical shape to reduce weight. The blind hole part 20
The upper part is closed by a partition wall 23, and at the upper end of the bracket 17 above this, boss parts 24 which are symmetrically inclined inwardly in the vehicle width direction on the left and right sides are provided to protrude obliquely upward. The portion 24 is hollowed out and formed into a cylindrical shape in the same manner as described above.

A bottom bridge 25 made of a pipe material is installed between the boss portions 22 that protrude laterally so as to face each other inside each of the above brackets 17, 17, and the inner diameter portion of the pipe material fits into the boss portion 22. The end portions 25a are fitted into the boss portion 22 and integrally joined by welding. On the other hand, connecting members 26 made of pipe material are connected to the left and right boss portions 24 protruding above the left and right brackets by fitting the lower end portions 26a in the same manner as described above. They are erected in a V-shape so that they are close to each other. left and right connecting members 26 symmetrically inclined inward in the width direction;
A top bridge 27 made of, for example, a plate material is horizontally suspended between the upper ends of the top bridge 26, and both ends 27a of the top bridge 27 are bent diagonally upward and fastened to the upper ends 26b, 26b of the connecting members 26, 26 with bolts 28 or the like. do. Thus, the top bridge 27 is the buffer 11.
The connecting member 26 and the upper and lower bridges 25 and 27 form a trapezoidal front fork upper part, and the symmetrical inclination of the connecting member 26 inward in the width direction increases the width of the top bridge 27. is set smaller than the bottom bridge 25. A steering stem 28 is installed vertically at the center of the upper and lower bridges 25, 27 in the vehicle width direction, and this is pivotally connected longitudinally to the head tube described above.
A handle 29 is attached to the top bridge 27.

Next, to explain the action and effect in detail, the reaction force from the road surface to the front wheel 16 is absorbed by the axial expansion and contraction movement of the shock absorbers 11, 11, and the load on the shock absorber 11 is absorbed by the upper member 12.
The connecting portion acts on the bottom bridge 25, which has both ends directly connected to it via the bracket 17. On the other hand, a connecting member 26 is directly connected to the bracket 17 so as to tilt its axial direction, and is supported by the top bridge 27. As a result, the load on the shock absorber 11 is also transmitted from both ends of the bottom bridge to the connecting members upward, and the bending load on the bottom bridge is smaller than in a case where the connecting members are installed inward from the connecting portions of the bottom bridge. Furthermore, since the bottom bridge is made of pipe material, there is no need to unnecessarily increase the strength and rigidity of the bottom bridge. In addition, the front fork is arranged at an angle in relation to the caster angle,
Therefore, a torsional load acts on the bottom bridge 25, but in the present invention, the connecting member 26 and the bottom bridge 25 are directly connected to the bracket 17, and therefore have high rigidity, so that the torsional load can be absorbed by bending the shock absorber 11. In this respect, there is no need to unnecessarily increase the strength and rigidity of the bottom bridge as it would absorb torsion by itself. Therefore, the bottom bridge is made of a material such as pipe material to reduce weight and
The structure can be simplified.

As is clear from the above, according to the present invention, the bridge part is advantageous in terms of strength in front wheel suspensions for off-road tricycles, etc., and the bridge part can be made of welded pipe material without casting, etc., to achieve practical strength and rigidity. It has many advantages such as being able to be obtained while maintaining the same quality, and being able to reduce weight, ease of manufacture, and cost reduction.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Figure 1 is a side view of the tricycle, Figure 2 is a plan view of the same, and Figure 3 is a side view of the tricycle.
The figure is an enlarged front view of the front fork, FIG. 4 is a longitudinal sectional view of the same portion, and FIG. 5 is a cross sectional view of the main part. In the drawing, 10 is a suspension device, 11 is a shock absorber, and 12 is a suspension device.
is the upper member, 16 is the front wheel, 17 is the bracket, 25
2 is a bottom bridge, 26 is a connecting member, and 27 is a top bridge.

Claims (1)

[Scope of utility model registration request] A bracket is fixed to the upper members of left and right shock absorbers that support the front wheels, and the opposing inner sides of the brackets are connected by a bottom bridge member, and a connecting member whose upper part is symmetrically inclined inward in the vehicle width direction on the bracket. 1. A steering front wheel suspension system for a vehicle, characterized in that the connecting member is connected by a top bridge member shorter than a bottom bridge.