Different types of three-or more wheeled motor vehicles are presently known, all of them being characterized by the fact that the attitude when handling a curve is the same as that when running on a straight line. In order to improve the behaviour when handling a curve one can resort to larger tyres, more rigid suspensions, and a better load distribution that, however, remains always unchanged.

On the other hand, it is known that the typical behaviour of the motorcycles when handling a curve is an inclination causing the centre of gravity to shift to the inside of the curve so that a higher speed can be reached under the same road holding.

However, the equilibrium problems for the two-wheeled vehicles in case both of rain and irregular road surface are well known.

The present invention seeks to overcome the problems of the prior art by providing a vehicle having the advantages of the motorcycles with respect to the load distribution when handling a curve, even though a stable equilibrium is guaranteed because of the three

wheels. This is accomplished by providing a vehicle with two front wheels and one rear wheel having a frame capable of causing the wheels to steer and the position of the driver to incline so that the centre of gravity is shifted to the inside of the curve which is being run across.

More particularly, the frame is provided with a rear portion (on which only one cushioned driving wheel is placed) which is able to rotate about its own longitudinal axis and is secured to a trapezoidal front portion that is capable of being deformed under the control of a transversal shock absorber. The two steering wheels are supported by said front portion.

A better understanding of the invention will ensue from the following description with reference to the accompanying drawings that shows some preferred embodiments only by way of a not limiting example.

In the drawings: Figs. 1,2 and 3 show a side elevation view, a front view and a top plan view of a first embodiment of the invention in vertical position, respectively; Figs. 4,5 and 6 show views of the invention similar to the preceding views but in inclined position, respectively; Fig. 7 is a perspective view of the coupling between the front wheel and the frame capable of being

deformed; Figs. 8,9 and 10 are views similar to Figs 1 to 3 showing a second embodiment of the invention; Fig. 11 shows the second embodiment of the invention in inclined position like Fig. 5; Figs. 12,13 and 14 show a third embodiment of the invention like Figs. 1 to 3; Fig. 15 shows the third embodiment of the invention in inclined position like Fig. 5.

In the first embodiment disclosed the frame of the invention consists of a trapezoidal car frame system capable of being deformed and having the peculiar feature that the front wheels together with the central portion carrying the driver can be inclined.

As shown in Figures 1 to 7, such a construction can be used without essential modifications for outfitting both the driving positions similar to those of the scooters and the typical driving positions of motorcycles or motorbikes.

The steering of the front wheels about respective axes S, S'is controlled by handle bar 1 by means of a typical linkage system (not shown).

According to the invention the whole deformable frame can rotate about a longitudinal horizontal axis with respect to which suspension arms 2 and 3 are shifted.

As can be seen from the above-mentioned figures, steering axes S, S'of each front wheel follow the movement of inclination of the respective wheel and remain always perpendicular to the axis of rotation AA'or BB'of the respective wheel.

The front wheels remain parallel to each other also during the side inclination because of the fact that the movable suspension arms 2 and 3 have only one central shock absorber M. During such a side inclination the frame rotates about fulcrums F, F' that follow the movement of the front wheels by shifting to a transversal horizontal direction.

As can be better seen thereafter, such a feature is very important as it prevents shock absorber M from being loaded or unloaded during the inclination so that the latter can also operate when the car is handling a curve unlike the conventional car shock absorbers.

Advantageously, this gives the motor vehicle according to the invention a better stability when handling a curve and an improved braking capability even though the typical driving attitude of a motorcycle is kept unchanged.

The advantage consists in that, unlike the conventional cars, the load acting on the forward shock absorber does not change when the motor vehicle inclines so that the behaviour of the frame is made more uniform and stable in all of the operation modes.

As far as the movable front portion of the frame is concerned there are provided two pairs of superimposed

adjacent arms, i. e. two horizontal upper arms 2 and two horizontal lower arms 3. Each pair is hinged at the centre of the frame at fulcrums A and A'lying on one another.

As shown in the figures, each arm 2 is connected at its ends to fulcrum F of the corresponding wheel and to fulcrum A; similarly, each arm 3 is connected at its ends to fulcrum F'of the corresponding wheel and to fulcrum A'.

The side shift of said central fulcrums A, A'with respect to the longitudinal vertical plane of the vehicle is caused by the inclination of the rear portion with respect to the same plane.

It is important to notice that central fulcrum A of upper arms 2 and central fulcrum A'of lower arms 3 are shared by the adjacent upper and lower arms, respectively. In fact, if each arm would be connected to a central hinge pin not coinciding with that of the adjacent arm, the movable frame system would cause the distance between the front wheels to change during the inclination, thus causing an irregular cushioning action as the position of the vehicle changes.

In the preferred embodiment disclosed a shock absorber M is mounted horizontally on the two lower arms 3 so that each end thereof is integral to the corresponding arm. Thus, the shock absorber exerts its action whenever the triangle formed by arms 3 changes (in the figures triangle F'A'F'is improper because it is a straight line) or whenever arms 3 rotate to each other.

If a wheel rises with respect to the other, arms 3 will take the position of a wide"V", if a wheel lowers with respect to the other said arms 3 will take the position of an overturned wide"V".

As can be clearly seen from the figures, arms 2 and 3 of each (right and left) side remain always parallel to one another.

It is self-evident that shock absorber M can also be placed on the upper arm pair 2 in the same way and on the same operating conditions.

It should also be appreciated that the driver can control the inclination of the motor vehicle according to the invention by shifting his body (like in the two-wheeled motorcycles) while the steering of the wheels is controlled by handle bar 1.

To this end, it should be noted that, as clearly shown in Figures 2 and 5, the rotation of the rear portion of the frame about its own longitudinal axis causes the horizontal upper arms 2 to shift crosswise with respect to the horizontal lower arms 3 with the result of a lateral inclination of the wheels.

A second embodiment of the invention shown in Figures 8 to 11 provides a construction of the front portion of the frame which can be simplified with respect to the preceding solution. In this case, the steering front wheels do not incline sidewise as the rear portion is inclined.

It should be appreciated that, when handling a curve, also such a solution allows the centre of gravity to

be shifted to the inside of the curve, thus improving the wheel grip and the road holding of the vehicle because of the movement of the driver moving his body like in a motorcycle.

Advantageously, the shock absorber system is essentially the same as that described in the preceding embodiment so that the action of the shock absorber is exerted irrespective of the fact that the trajectory is straight or curved.

To this end, it should be appreciated that the fore carriage differs from that of the preceding embodiment because of the lack of the pair of horizontal transversal upper arms 2.

Figures 9 and 11 show that axes AA'and BB'of each steering front wheel are always parallel to the ground, while the rear portion of the frame inclines like in the preceding embodiment by shifting advantageously the centre of gravity to the inside of the curve.

It is also very interesting that the front wheels can advantageously be driving wheels by the aid of universal joints, thus further improving the road holding and the wheel grip of the vehicle.

It is also possible to provide in the rear portion two wheels capable of inclining like the front wheels of the first embodiment. In the latter case the rear wheels are not steering so that the construction is further improved.

It should be noted that the present invention is not limited to vehicles provided with wheels. In fact a

third embodiment of the invention schematically illustrated in Figures 12 to 15 relates for example to a motor-sled.

Advantageously, without particular modifications, the previously described movable frame can be used to provide a motor-sled capable of inclining when handling a curve. To this end, it is sufficient to replace the front wheels with two runners or skis P with flat bottom and the rear driving wheel with a track C which is driven by the same gearing.

Such a solution highly increases the steering capability of the motor-sled of the invention over the conventional motor-sleds because the curves are handled, as well known, by the side leaves of the skis which are inclined by the skier during the change of direction.

Such a steering effect is further improved by using two skis of the known"carving"type which are characterized by a fitting at the waist, i. e. the width of the front and rear end portions is larger than the width of the central portion.

As an alternative to the flat-bottomed skis which reduce the friction with the snow and allows higher speeds to be reached, skis having a triangular cross section with the vertex directed downwards can also be used. In this case, the steering effect is also provided without inclining the front skis so that the simplified frame of the second embodiment can be used.

The present invention has been described and

illustrated according to preferred embodiments thereof, however, it should be understood that those skilled in the art can make equivalent modifications and/or replacements without departing from the scope of the present industrial invention.

For example a further application could relate to the navigation and provide a water motorcycle provided with a rear hull which can be inclined with respect to two front floating bodies which can be guided.