JPH0442231Y2 - - Google Patents

Description

[Detailed explanation of the idea] a Industrial application field The present invention relates to a straddle-type vehicle.

b. Prior Art Vehicles used for traveling on rough terrain are required to be easily balanced and have good maneuverability when a driver rides on the vehicle. Therefore,
A straddle-type four-wheeled vehicle has been developed that has two wheels on each of the front and rear wheels on a two-wheeled-type straddle-type frame. This straddle-type four-wheel vehicle uses a bar handle to steer the front wheels, and each wheel is equipped with a low-pressure balloon tire.

As shown in Fig. 4, this type of straddle-type four-wheeled vehicle has two front wheels 1 and two rear wheels 2, each of which has low internal pressure and a contact point with the ground. It is equipped with wide tires, so-called balloon tires 4. This four-wheeled vehicle has a bar handle 4 as a handle for operating the steering mechanism of the front wheel 1.
In addition, a bar step 5 is used as the step on which the driver's feet are placed. 6 and 7 are a front cover and a rear cover, and a seat 8 is placed on this rear cover 7.

In such saddle type vehicles, an improved frame of a motorcycle is used as a frame structure, and the structure of a four-wheeled vehicle is used as a support structure for the wheels. For this reason, in the case of a frame structure that employs a wisdombone suspension mechanism, the inclination of the kingpin with respect to the vertical line when viewed from the side, the so-called caster angle, is also
It is necessary to apply it appropriately as shown in the figure. Normally, the structure is such that the king pin is inclined at a certain angle with respect to the front suspension, and the caster angle θ (3
~6°).

C. Problems that the invention aims to solve By the way, if such a suspension system is adopted,
When the front wheel 1 hits a protrusion on the road surface, as shown in FIG. 6, the front wheel 1 tries to move in the Y-axis direction in response to the force F received from the inclination of the protrusion. Therefore, since the force that moves the front wheel 1 is only F _Y ,
The force with which the front wheel 1 overcomes the protrusion is small. At this time, the force F _X acting in the X-axis direction becomes a force that stops the movement of the front wheel 1, and the front wheel 1 feels like it is caught on the protrusion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a straddle-type vehicle that can solve the above problems and improve the ability of wheels to follow irregularities on a road surface.

d Means for Solving the Problems In order to solve the above problems, the present invention has two front wheels and two rear wheels equipped with balloon tires on each of the front left and right sides and the rear left and right sides of the frame, and a vertically long wheel mounted approximately in the center of the frame. This is a straddle-type vehicle in which a seat is mounted on a frame between the front and rear wheels, and the wheels are driven by an engine mounted on a frame between the front and rear wheels to travel on rough terrain. The upper and lower two frame members that support the control arm are formed to have an upward slope that is greater than the caster angle toward the front upward, and the caster angle of the wheel support portions of the upper control arm and lower control arm is set at a predetermined angle. This is because the mounting positions of the pivot portions of the upper control arm and the lower control arm are relatively shifted.

e Embodiments The present invention will be described in detail below with reference to illustrated embodiments.

In FIGS. 1 to 3, 10 is a vehicle body frame, 11 is a front suspension, and 12 is a swing arm for supporting the rear wheel.

The vehicle body frame 10 includes one tank rail tube 13, a seat rail 14 supported at the rear end of the tank rail tube 13, one end connected to both sides of the front end of the tank rail tube 13, and the other end connected to both sides of the front end of the tank rail tube 13. After extending diagonally downward at a predetermined interval, it is reversed to form a front frame portion 15a, further extended rearward to form a lower frame portion 15b, and its rear end is raised to form a seat rail. 14, a side bridge 16 that connects the upper side of the front frame portion 15a of the side member 15 to the lower frame portion 15b, and the middle of the side bridge 16 and the tip of the front frame portion 15a. It consists of a frame tube 17 that connects the two, and another reinforcing tube 18. The frame tube 17 and the lower frame portion 15b of the side member 15 are arranged to face forward at a predetermined angle α and to be inclined upward, and brackets 19a and 19b for mounting the front suspension 11 are provided in the middle thereof. are installed on each. The angle α is set to be greater than the normal caster angle of 3 to 6 degrees.

In the front suspension 11, the pivot portion 20a of the upper control arm 11a is fastened to the bracket 19S of the frame tube 17, and the pivot portion 20b of the lower control arm 11b is fastened to the bracket 19S of the frame tube 17.
is fastened to the bracket 19b of the lower frame portion 15b and is rotatably fixed.

The mounting positions of the pivot parts 20a and 20b are as follows:
Wheel support parts 21a, 21b of upper control arm 11a and lower control arm 11b
The caster angle θ is relatively shifted so that the caster angle θ is maintained at the normal caster angle θ.

That is, the middle O between the wheel support parts 21a and 21b
If the horizontal axis passing through is the X axis and the vertical axis is the Y axis, then the caster angle θ is the normal caster angle of 3 to 6 degrees.
The mounting positions of the frame tube 17 and the brackets 19a, 19b of the lower frame portion 15b are shifted by a predetermined width l so that

According to the saddle type vehicle configured as described above, when the front wheel hits a protrusion on the road, the first
As shown in the figure, the vehicle body frame 10 receives an axial force F _X from the frame tube 17 and the lower frame portion 15b, and the front wheel is lifted by the upward force F _r , making it easy to overcome the protrusion. I can do it. At this time, if the inclination angle α of the frame tube 17 and the lower frame portion is α=20°, then F _Y =Fcos(45−α)=Fcos25°=0.90F.

For example, compared to α = 3.5°, F _Y = Fcos (45
−α)=Fcos41.5°=0.749F, which proves the effectiveness of the frame structure of the present invention.

f. Effect of the invention As described above, according to the saddle-ride type vehicle of the invention, the two upper and lower frame members supporting the upper control arm and the lower control arm of the front suspension, which suspend the front wheels, are The upper control arm and the lower control arm are formed to have an upward slope that is greater than the caster angle, and the caster angle of the wheel support portion of the upper control arm and the lower control arm is a predetermined angle. Since the mounting positions of the pivot parts are relatively shifted, the climbing force against convex parts such as green stones can be improved. Further, since the mounting positions of the pivot portions of the upper control arm and the lower control arm are relatively shifted, the caster angle can be set to the normal caster angle.

[Brief explanation of the drawing]

1 to 3 show a straddle-type vehicle according to an embodiment of the present invention, FIG. 1 is a conceptual diagram showing the position of the vehicle support part in the control arm of the front suspension, and FIGS. The figures are a side view and a perspective view showing the frame structure of a straddle-type four-wheel vehicle that employs a front wishbone type suspension mechanism. FIG. 4 is a perspective view showing a straddle-type four-wheeled vehicle, FIG. 5 is a conceptual diagram showing a caster angle, and FIG. 6 is a conceptual diagram showing a conventional frame structure. 10...Vehicle frame, 11...Front suspension, 11a...Upper control arm, 11b...Lower control arm, 15
...Side member, 15b...Lower frame section,
17...Frame tube, 20a, 20b...
Pivot part, 21a, 21b...wheel support part.

Claims (1)

[Scope of utility model registration request] There are two front wheels and two rear wheels equipped with balloon tires on each side of the front left and right sides and rear left and right sides of the frame.A seat is placed vertically in the center of the frame, and the wheels are powered by an engine mounted on the frame between the front and rear wheels. The vehicle is a straddle-type vehicle that travels on rough terrain, and the upper and lower two frame members that support the upper and lower control arms of the front suspension, which suspends the front wheels, are mounted on a caster with the upper and lower frame members facing forward and upward. The mounting positions of the pivot portions of the upper control arm and the lower control arm are formed so that the front slopes upward by a angle greater than or equal to the angle of A straddle-type vehicle characterized by a relatively shifted position.