Method and device for the suspension of a motor vehicle

The present invention relates to a method and device for the suspension of a motor vehicle and particularly for the temporary adjustment of the suspension of a motorcycle.

In the known manner, the suspensions of motor vehicles are arranged with the aid of separate shock absorbers. The general principle in shock absorbers is that the flow of the gas/liquid of a shock absorber, which contains either a gas or a liquid or both, is limited in one way or another in one direction or in both directions. This equalizes and attenuates the forces acting on the suspension. This is of great importance, for example, for the adhesion of the tyre on the pavement, as the wheel is thus prevented from separating from the pavement and so creating roadholding problems.

To achieve the best possible result, each wheel of a vehicle is equipped with a separate shock absorber.

In the case of motorcycles, the problems are greater than for a four-wheeled vehicle, and more accurate and better shock absorbing is very necessary.

Among motorcycles, there are motorcycles used in competitions, which are used for both track competitions and also in competitions held on rough ground, such as motocross, which greatly stress the condition of both the motorcycle and the rider. Special competition shock absorbers have been developed for competition motorcycles of this kind, because conventional shock absorbers are totally insufficient to provide properties equal to these extreme conditions.

The accompanying Figure 1 shows one known type of competition-motorcycle shock absorber, which is described herein, because the shock absorber according to the invention too is based on this known construction.

Thus the shock absorber of Figure 1 represents an absorber of the so-called prior art. The absorber is attached between the frame of the motorcycle and the suspension components of its wheel. In this case, the attachment is implemented by means of bolts at the upper and lower ends of the absorber, which run through holes, marked with the reference numbers 2 and correspondingly 3, which are located in the body pieces 4 and correspondingly 5. The body pieces are connected by a tubular upper component 6 and a lower component 7, which can be mainly classified as being rod-like but equipped with a channel. There is a pre- tensioned spring 8 between the body pieces 4 and 5.

In the upper tubular component 6 there is a piston 12, which, in a known manner, when it moves alters the ratio of the volumes above and below the piston.

In the upper body piece 4, there is a channel 9, which leads to a reservoir 10. When an impact, or other force tries to raise the piston in the tube 6, the liquid volume above the piston tries to flow through the channel 9 to the reservoir 10. In practice, however, the volume of moving liquid flowing to the reservoir 10 is only the volume displaced by the rod 7 pushing the piston into component 6. This is because there is at least one opening 18 in the piston 12, which is closed from beneath by a flexible flap 19, which admits the liquid volume to move to the space below the piston, when the piston moves upwards. However, this same flap prevents a flow through the opening or openings 18, when the piston moves downwards. The openings 13, 14, which are described in the following, then act as a flow opening.

Screws 11 are used to adjust the flow opening of the flow channel 9 to an acceptable level, so that the damping effect will be of the desired magnitude. Pushed by the lower component 7, the piston 12 has moved to some extent upwards from the position shown in Figure 1 , even to such an extent that it is close to the upper part of the tubular component 6 from where it seeks, due to the effect of the spring 8, to return to the level of the situation shown in Figure 1.

The return is the second part of the shock-absorbing event, which is referred to by the term rebound. The following system is used to adjust the rebound. In the

centre of the piston 12, there is a flow channel 13, the opening on the base of which is bounded by the upper end of the rod 15. In the rod 7, there are also flow openings 14, through which the flow running to the channel 13 can enter the space above the piston 12, from the space below the piston. The vertical position of the adjustment rod 15, and thus also the amount of the flow through the openings 14, 13 is adjusted using an adjustment screw 16. The screw 16 is thus used to determine a suitable magnitude for the rebound time. Thus in this way the two adjustment-screw system is used to create the basic level of shock absorbing most satisfactory to the rider.

Though the system described works quite well, it nevertheless lacks any possibility of making adjustments while riding. This is due to the fact that, when riding in a motocross event, for example, it would be very necessary to adjust particularly the rebound, which in jumps, for example, tends to give the jump additional spring and to create a situation, in which the rider cannot use the greatest possible speed, as instead the jump tends to become too long, thus increasing the riding time achieved in competitions. There are other situations too, in which adjustment would be useful, for example, in starting acceleration.

In general, it can be stated that, for example, when riding in a motocross event, damping is often too hard when braking, and too soft during acceleration and when landing from jumps. During braking, the weight moves onto the front end, which makes the rear-end damping too hard. During acceleration, on the other hand, the rear end tend to press down too much and interfere with steering. The adjustment is thus too soft. Also when landing from jumps, the suspension is too soft, often being compressed completely.

The present invention is intended to create a method and device, with the aid of which automatic adjustment of rebound can be achieved, but also a method and device, which the rider too can affect to a certain degree. This will create effects that increase riding speeds, and also, for example, an effect increasing starting acceleration.

The aforementioned and other benefits and advantages of the invention are achieved in the manner described as characteristic in the accompanying Claims.

To describe the invention, reference is made to

Figure 1 , which are stated above, refers to the solution of the prior art;

Figure 2, which shows the solution according to the invention, in relation to the so- called basic state, in which the shock absorbing is tight and the adjustment rod 15 raised; and

Figure 3, in which an impact to the vehicle has lead to a reduction in damping, or in which damping has been reduced due to braking.

The basic idea of the invention is that the basic adjustment of the damping can be taken care of automatically, while part of the operation of the damping can be influenced in other ways.

In the following, reference is made to Figures 2 - 3, which show the arrangement according to the invention. Figures 2 - 3 show only a cross-section of the lower end of the shock absorber. The arrangements in the upper parts of the shock absorber can be, for example, similar to those shown in Figure 1 , in connection with the description of a shock absorber according to the prior art.

The basic setting of the arrangement according to the invention is made by means of a screw 18 and a spring 19, which generally rest on an adjustment piece 20, equipped with a sloping surface. This resting takes place by means of the piston described in the following. In the situation shown in Figure 2, the force of the spring 19 is sufficient to push the adjustment piece 20 far enough to the left (in the figure) to cause the adjustment rod 15 to rise, due to the sloping at its lower end and the complementary sloping surface 22 in the adjustment piece 20. The damping is now at a maximum.

The adjustment operates in such a way that, when an impact strikes the vehicles, the shock absorber seeks to compress into itself and shorten. This causes the pressure to increase inside the upper part 6 of the shock absorber. The pressure acts on the adjustment road 15, which seeks to move downward due to the pressure and to move the adjustment piece 20 to the right, when the downward movement of the rod becomes possible and the damping diminishes as the flow openings become larger. The damping is thus self-regulating. The final situation, i.e. the reduction in the damping effect is shown in Figure 3, in which the adjustment rod 15 has been pushed to the right and the lower end of the adjustment rod has been pushed along the sloping surface 22 to its lower position.

It is obvious, that the movements described are not on-off movements, but than everything takes place gradually. The basic setting can be changed very easily and simply by tightening or slackening the screw 18.

As stated above, braking is one problem, at least in motocross, or when performing other demanding riding. The damping of the rear wheel in particular is too powerful during braking. Allowance is made for this with the aid of the adjustment components 16 and 17. The situation corresponds entirely to Figure 3.

The functions of the said components 16 and 17 are as follows. Reference number 16 marks the hydraulic cylinder. Pressure is introduced to the hydraulic cylinder particularly by the pressure of the vehicle's hydraulic brakes being connected to the cylinder 16, through a connector 21. The pressure brought to the cylinder, which is a result of the braking of the vehicle, causes the piston 17 to move to the right in the figure, against the force of the spring 19. When it moves, the piston 17 releases the pressure it directs to the adjustment rod 15, so that the adjustment rod 15 can press downward as the adjustment piece 20 moves to the right in Figure 3. In the manner described above, the damping then diminishes.

If it is wished to make to part of the system connection to the brakes a separate adjustment system, its own adjustment pedal or adjustment handle is reserved for it, which the rider can use at his discretion. Thus the adjustment piece 20 can be moved and the damping thus affected, by means of any suitable arrangement

whatever, hydraulic or mechanical. The adjustment can thus also take place otherwise than by using a hydraulic-cylinder-type adjustment member.

As described above, the invention brings added value to shock absorbing in a quite simple and inventive manner.