JPH0434083Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a suspension system for a two-wheel front wheel vehicle having two front wheel axles and one rear wheel axle.

[Prior Art] Vehicles having such a suspension system are widely used in trucks and the like. For example, as shown in FIG. There is a mounting structure 3
is placed. A front axle 4 and a front axle 5 having steering shafts and a rear axle 6 having drive wheels are attached to the vehicle body 1 via suspension devices 7, 8, and 9, respectively. Normally, the same springs are used for the suspension devices 7 and 8 of the front and rear axles 4 and 5, and the rear axle 6 is located at a position offset rearward by a dimension L with respect to the center of gravity W of the bodywork 3. It is provided. Also, the load factor of the tires on each axle 4, 5, and 6 is, for example, 1:
Since it is designed to have a ratio of about 1:2, the position of the center of gravity W mentioned above is appropriate when the vehicle is loaded, but when the vehicle is empty, the center of gravity W moves forward in the drawing, that is, toward the cab 2 side, so when the vehicle is empty, the rear axle is The disadvantage was that the load on the 6 was very light, making it difficult to start on snowy roads, etc., and easily causing slips.

In order to overcome this drawback, the present applicant changed the spring constants of the springs 7 and 8, which are the suspension devices for the front two axles 4 and 5, in Utility Application No. 59-172384, so that the spring constants of the front and rear axles were changed from the front to the front. We proposed a technology in which the shaft is made smaller under light loads than the spring constant.

As a result of further research, the present inventors have discovered that the technique can be further improved.

[Purpose of the invention] Therefore, the purpose of the invention is to provide a suspension system for a two-wheel front axle vehicle that can reduce the load on the front and rear axles when the vehicle is empty and share the reduced load between the front and rear axles. be.

[Configuration of the invention] According to the suspension system for a front two-axle vehicle according to the invention,
The spring constant of the suspension system for the front axle is smaller than the spring constant of the suspension system for the front and rear axles, and the spring constant for the front axle is set so that the shared load on the front axle and the shared load on the front axle are substantially the same during loading. The amount of deflection is made larger than that of the front and rear axes.

The spring constituting the suspension system for the front axle may be nonlinear, and its spring constant may be smaller than the spring constant of the suspension system for the front and rear axles when the vehicle is empty.

[Effects of the invention] When the vehicle is loaded, the load is distributed appropriately to each axle, but when the vehicle is empty, the center of gravity moves toward the cab (forward), and the loads from the front and rear axles are transferred to the rear axle. However, the change (decrease) in the amount of spring deflection of the front axle and the front and rear vehicles is almost the same. The front and rear axles have a small spring constant, so the amount of reduction in axial load is small, and the front and rear axles have a large spring constant, so the amount of reduction in axial load is large. As a result, the front axle and the rear axle bear the load to the extent that the axle load on the front and rear axles decreases when the vehicle is empty, and the load on the rear axle increases relatively. Therefore, slips and the like are less likely to occur when the vehicle is empty.

[Example] When implementing the present invention, any type of suspension device can be used, and the purpose can be achieved by specifying the spring constant as described above. The explanation will be given by taking the leaf spring type suspension device shown in the figure as an example.

FIG. 1 shows a suspension system for a front front axle and a front and rear axle in which the present invention is implemented, and similarly to _FIG . is rotatably supported. This front axle is connected to a suspension device, that is, a leaf spring 7 in the illustrated example.
The leaf spring 7 is attached to the vehicle body 1 via the following, and both ends of the leaf spring 7 are supported by the vehicle body 1 at fulcrums S ₁ and S ₂ in a known manner. Also provided at the rear of the front front shaft 4,
The front and rear axle 5, which rotatably supports the steerable front and rear wheels _W2 , is attached to the vehicle body 1 via a suspension device, that is, in the illustrated example, a leaf spring 8, and both ends of the leaf spring 8 are known in the art. It is supported by the vehicle body 1 at fulcrums S ₃ and S ₄ in this manner. A in the diagram
is a shock absorber.

According to the present invention, in order to make the spring constant of the leaf spring 7 smaller than the spring constant of the leaf spring 8, and to make the amount of deflection of the leaf spring 7 larger than the amount of deflection of the leaf spring 8,
In the illustrated embodiment, the fulcrum supporting the leaf spring 7
The length L ₁ between S ₁ and S ₂ is made larger than the length L ₂ between the fulcrums S ₃ and S ₄ supporting the leaf spring 8.

FIG. 2 shows an example in which a leaf spring 7a having nonlinear characteristics is used for the front shaft. In the illustrated example, the leaf spring 7
a is composed of four leaf elements a, b, c, and d, and the upper two leaf elements a and b are integrally constructed, but the third leaf element c only has its central part. It is integrated with the leaf elements a and b, and therefore a gap δ is formed at both end portions. 4
The leaf element d at the bottom of the second sheet is integrated with the leaf element c, but its length is shorter than the leaf element c. Therefore, when the car is empty, a gap e is formed as shown by the solid line, but when the car is loaded, the leaf elements a and b are bent as shown by the chain line 7b, and the leaf element b comes to engage with the leaf element c, resulting in a gap e. disappears. After that, the leaf elements c and d bend, so the spring constant after the gap e disappears is different from the spring constant when the gap e exists, and a nonlinear spring constant can be obtained.

Figure 3 is a diagram showing the spring constants of the front and rear axles of the suspension system in which the present invention has been implemented, with the horizontal axis representing the amount of spring deflection δ (mm) and the vertical axis representing the spring load ρ (Kg). It is shown. In the figure, straight line Ka is a line indicating the spring constant of the front-front axis, and straight line Kb is a line indicating the spring constant of the front-rear axis. The intersection point A of both straight lines Ka and Kb is when the vehicle is loaded (rated), the load on both springs is P ₁ , the amount of deflection of the front axle is δ ₁ , and the amount of deflection of the front and rear axle is (δ ₁ − δd).

Now, assuming that, as in the prior art, the spring constants of the front axle and the front and rear axles are equal and are shown by the straight line Ka in Fig. 1, the load on the front axle when the vehicle is empty is Pb,
The amount of deflection is δb, and the movement of the center of gravity W causes the rear axle to float more or less, so the front and rear axles sink more and more and the front and rear axes float more or less, and the amount of deflection of the front and rear axes becomes smaller. Therefore, the load on the front and rear axes is P ₂ and the amount of deflection is δc.

However, according to the present invention, the spring constant of the front axle suspension is smaller than the spring constant of the front and rear axle suspensions, that is, the tangent of the straight line Ka is
Since the tangent of Kb is smaller (Ka is smaller than Kb), the spring load Pa on the front axle when the car is empty is slightly larger than the conventional example Pb, and the spring load Pc on the front and rear axles is slightly larger than the conventional example P. It comes at a much lower place than ₂ . In other words, since the straight line Kb is below the straight line Ka, the spring load Pc on the front and rear axes is quite low.

Therefore, since the value of the decrease in the load on the front-rear axis (P ₂ - Pc) is greater than the increase in the load on the front-rear axis (Pa - Pb), the value of (P ₂ - Pc) - ( Pa-
Pb) is applied. In other words, a portion of the decrease in the spring load on the front and rear axles is borne by the front and rear axles, so the spring load on the rear axle is relatively increased, and slips and the like can be prevented.

In FIG. 3, the broken line Kc is an example in which the spring constant of the front axle suspension is non-linear. In this example, the broken line Kc coincides with the straight line Kb at the point x, so that the spring constant is small (the tangent is small) where the spring load is small. In this case, when the vehicle is empty, the spring load on the front axle is Pf, the spring load on the front and rear axles is Pd, and the load on the rear axle can be increased in the same way as described above.

[Summary] As described above, according to the present invention, when the vehicle is loaded, the axle loads on the front axle and the front and rear axles are the same, and when the vehicle is empty, the spring constant of the front axle is smaller than the spring constant of the front and rear axles. Therefore, even if the center of gravity moves toward the cab when the vehicle is empty, the load on the front and rear axles can be shared between the front axle and the rear axle, and the rear axle has a reduced load compared to the conventional model by the amount of the shared load. Since this increases, slips and the like can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an example of a front-front axis and anteroposterior axis in which the present invention is implemented, Fig. 2 is a side view showing an example of a leaf spring having a nonlinear spring constant, and Fig. 3 is a side view showing an example of a leaf spring with a nonlinear spring constant. FIG. 4 is a side view of a front wheel two-axle vehicle to which the present invention is applied. 1...Vehicle body, 4...Front front axle, 5...Front and rear axle, 6
... Rear axle, 7.8, 9 ... Suspension system, Ka, Kc...
...Spring characteristics of the front and rear axles, Kb...Spring characteristics of the front and rear axles.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a suspension system for a two-axle front vehicle having two axles for the front wheels and one axle for the rear wheels, the spring constant of the suspension system for the front axle is smaller than the spring constant for the suspension system for the front and rear axles. A suspension system for a two-axle front wheel vehicle, characterized in that the amount of deflection of the spring on the front axle is greater than that on the front and rear axles so that the load shared by the front axle and the load shared by the front and rear axles are substantially the same when loaded. . (2) Claim 1 of the Utility Model Registration Claim in which the suspension system for the front axle has non-linear characteristics and the spring constant of the suspension system for the front axle is smaller than the spring constant for the suspension system for the front axle when the vehicle is empty. Suspension system for front two-axle vehicles.