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1. (WO2018158743) METHOD OF CONTRASTING THE JUMPING TRIGGERED BY A RESONANCE OSCILLATION IN A MOTOR VEHICLE WITH THREE OR FOUR WHEELS
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DESCRIPTION

"Method of contrasting the jumping triggered by a resonance oscillation in a motor vehicle with three or four wheels"

Field of application

The present invention relates to a method of contrasting the jumping triggered by a resonance oscillation in a motor vehicle with three or four wheels.

In particular, the method according to the invention may be implemented in a motor vehicle provided with two steering and rolling wheels at the front and a rear drive wheel with fixed axle at the rear.

Prior art

In a rolling motor vehicle, the term "jumping" means an alternating oscillation movement of the front rolling wheels, triggered by a resonance of the rolling mechanism which ensures the rolling of the two front wheels.

Generally, this resonance of the rolling mechanism is triggered and/or fed by the road profile, for example by a hole, a braking, and is also influenced by the angles of the wheel with respect to the ground, and therefore by rolling and steering.

In this situation, rolling vehicles that do not have adequate damping on the roll can develop an alternating jumping of the two front rolling wheels during which the shock absorbers do not work and therefore do not help to dampen the event.

The onset of this phenomenon - if not properly countered or controlled - can be extremely dangerous, especially if it occurs at high speeds. In these cases, an uncontrolled jumping can in fact cause the loss of control of the motor vehicle, in extreme cases even resulting in the breaking of the frame, with potentially very serious consequences on the driver's safety. Motor vehicles with front rolling wheels having a high rolling inertia are much less prone to jumping. This is the case, for example, with rolling motor vehicles in which the rolling kinematic mechanism (rocker arm) which transfers the load between the wheels consists in an articulated rolling quadrilateral which engages the mass of the vehicle itself. This introduces a delay in the motion of the wheels which interferes with the resonance.

A first possible approach to contrast the onset of jumping phenomena therefore consists in increasing the rolling inertia, thus reducing the risk of triggering the jumping resonances.

A second valid approach if the trigger is due to the braking forces, thus horizontal on the ground, is to ensure that the trajectory of the wheels in spring/rolling is as vertical as possible and thus decoupled from such horizontal stresses: this is achieved by tilting the hinges of the rolling quadrilateral by such a value that the vehicle under braking, by lying on the forecarriage, approaches the parallelism to the ground.

Another approach is to remove the jumping resonance from the normal operating conditions of the vehicle by varying the yaw stiffness of the motor vehicle structure; in this way, the risk of the occurrence of such a phenomenon is reduced. In this technical solution, reinforcement bars are used which connect parts of the frame in order to create a static reinforcement in certain areas to reduce jumping phenomena.

More specifically, in the vehicle reference system, a yaw is defined as a rotation about a vertical axis with respect to the ground. Therefore, increasing the yaw stiffness means reducing the deformation (within certain values, elastic or such as to be cancelled when the stress ceases) caused by the moment of a longitudinal force applied to a single wheel (also equivalent to loads of different entities applied to both wheels). The jumping is related to the yaw deformation because the wheel in the deformation of its support finds the least contrast to move in the direction of the suspension, thus generating an equal force on the opposite wheel because the rocker arm is devoid of damping; therefore, the stiffening does not cancel the jumping once occurred but prevents it by shifting up its frequency related to the yaw deformation.

Approaches related to interventions on the damper hydraulics are also possible, but they are too complex to implement and generally not very effective. The jumping is in fact due to oscillations of the rolling mechanism, which the shock absorbers are not able to significantly influence. In fact, once the jumping has been triggered, the wheel moves together with the entire suspension of that side upstream of the rolling quadrilateral. Therefore, changing the characteristics of the shock absorbers does not affect the phenomenon. Also in this case, the jumping is an oscillation of the quadrilateral which "sees" at the opposite masses consisting of the wheel and suspension assembly which move rigidly. The shock absorbers during the oscillation do not change in length, they do not vary their response in terms of force and therefore any modification to their spring and hydraulics features is useless.

In general, to date, all the anti-jumping approaches adopted in rolling motor vehicles are aimed at avoiding the resonance of the rolling kinematic mechanism and the consequent jumping phenomenon.

In the case (however remote) of onset of the jumping resonance, it is not in fact possible to prevent it from turning into a dangerous alternating jumping of the wheels. In that case, the (difficult) control of the motor vehicle is in fact left to the driver's ability.

In the field of rolling motor vehicles, there is therefore the need to identify and implement strategies to counteract the jumping of a rolling motor vehicle, which can be automatically adopted by a motor vehicle control system or possibly by the driver's decision after the roll resonance has been triggered to dampen the oscillations of the rolling kinematic mechanism, preventing them from turning into a dangerous alternating jumping of the front wheels.

Disclosure of the invention

Therefore, the object of the present invention is to eliminate or at least reduce the above drawbacks of the prior art by providing a method of contrasting the jumping triggered by a resonance oscillation in a three or four-wheeled rolling motor vehicle which, in the event of onset of a resonance of the rolling kinematic mechanism and consequent triggering of an alternating jumping of the front wheels, allows to dampen such a jumping phenomenon before it assumes an intensity such as to cause the loss of control of the motor vehicle.

A further object of the present invention is to provide a method of contrasting the jumping triggered by a resonance oscillation in a motor vehicle with three or four wheels which is operatively reliable and easy to implement.

Description of the figures

The technical features of the invention can clearly be seen in the content of the claims below, and its advantages will become more readily apparent in the detailed description that follows, made with reference to the accompanying drawings, which illustrate one or more embodiments thereof which are purely exemplary and non-limiting, in which:

- figure 1 shows a front view of an example of a rolling motor vehicle in which the method of contrasting the jumping according to the invention can be implemented, such a motor vehicle being provided with a roll block system which operates directly on the rolling kinematic mechanism; and

- figures 2, 3 and 4 show three perspective views of the forecarriage of three examples of rolling motor vehicles in which the method of contrasting the jumping according to the invention can be implemented, such motor vehicles being provided with three different roll block systems, having in common the fact that they operate indirectly on the rolling kinematic mechanism by acting on the axle journals of the two front rolling wheels.

Detailed description

The present invention relates to a method of contrasting the jumping triggered by a resonance oscillation in a motor vehicle with three or four wheels.

For the purposes of the present invention, it should be noted that the term motor vehicle should be considered in a broad sense, encompassing any motor vehicle having at least three wheels, i.e. two front wheels and at least one rear wheel. Therefore, the definition of motor vehicle also encompasses the so-called quads, with two wheels at the forecarriage and two wheels at the rear.

In particular, the method according to the invention may be implemented in a motor vehicle provided with two steering and rolling wheels at the front and a rear drive wheel with fixed axle at the rear.

In general, as illustrated in the accompanying figures, the method according to the invention can be implemented in a rolling motor vehicle comprising:

- a forecarriage frame 16;

- at least a pair of front wheels 10', 10' kinematically connected to each other and to the forecarriage frame 16 by means of a rolling kinematic mechanism 20; and

- a roll block system 100 adapted to block the rolling of the two front wheels 10', 10".

The roll block system 100 acts directly or indirectly on the rolling kinematic mechanism 20.

The rolling kinematic mechanism 20 may have any configuration provided that it is functional to ensure the front wheels to roll in a synchronous manner.

In particular, such a rolling kinematic mechanism may be a system configured as an articulated quadrilateral system. Alternatively, the rolling kinematic mechanism may be, for example, a suspended longitudinal arm system.

In particular, the rolling motor vehicles illustrated in the accompanying figures are all provided with a rolling kinematic mechanism consisting of an articulated quadrilateral system.

More in detail, as illustrated in the examples in figures 1 to 4, such an articulated quadrilateral system comprises a pair of cross members 24 hinged to the forecarriage frame 16 at middle hinges 28. The cross members 24 are connected to each other, at opposite transverse ends 40, 44 by means of uprights 48 pivoted at said transverse ends at side hinges 52. The cross members 24 and the uprights 48 define the above articulated quadrilateral 20. The suspensions and the wheel bearing axle journals are mechanically associated with the uprights of the articulated quadrilateral rolling kinematic mechanism.

The rolling motor vehicle shown in Figure 1 is described in particular in the European patent EP1561612B1 . The rolling motor vehicle is provided with a rolling kinematic mechanism 20 with an articulated quadrilateral structure and two independent front suspensions 200. The roll block system 100 comprises a mechanical clamp 101 which acts on a sector of a brake disc 102 fixed to a cross member 24 of the articulated quadrilateral. The mechanical clamp 101 can be operated in engagement on disc sectors 102 to block the movements of the articulated quadrilateral and thus prevent the roll allowed thereby. The roll block system 1 10 also comprises two hydraulic clamps 103 which are simultaneously operated by an electric motor and act on rods 104 placed in parallel with the shock absorbers 200 so as to prevent roll due to an asymmetrical suspension of the two wheels. In this case, the roll block system 100 acts directly on the rolling kinematic mechanism.

The rolling motor vehicles illustrated in Figures 2, 3 and 4 are described in particular respectively in the Italian patent application no. IT 102015000088087, in the Italian application no. 102015000088090 and in the Italian application no. 102015000088097.

More in detail, each of these three motor vehicles is equipped with a rolling kinematic mechanism with an articulated quadrilateral structure. Unlike the motor vehicle shown in Figure 1 , the roll block system 100 of the motor vehicles shown in Figures 2, 3 and 4 does not act directly on the rolling kinematic mechanism 20, but indirectly on an element which is added to the rolling structure of the motor vehicle and is specifically intended for the purpose. More in detail, such an additional element consists of a direct interconnection element between the axle journals 50 of two rolling wheels, mechanically released from the frame of the motor vehicle. "Axle journal" of a wheel is the mechanical part of the motor vehicle intended to support the rotation pin of the wheel itself and interconnected it kinematically to the suspensions, the steering device and, in the specific case, to the kinematic roll mechanism. The axle journal can be kinematically integral with the wheel pin 51 , which in turn supports the wheel through bearings. In that case, the axle journal may be made integral with the wheel pin or be mechanically constrained thereto to form one piece. As an alternative, the axle journal can be kinematically integral with the wheel pin, which in turn supports the wheel through bearings.

Such a roll block system - as kinematically released from the effects induced by the suspensions - allows blocking all the roll movements by acting only on such an additional element, thus including the roll movements generated by an asymmetrical spring movement of two rolling wheels.

More in detail, in the rolling motor vehicle shown in Figure 2 and described in Italian patent application no. 102015000088087 (incorporated herein as a reference), the roll block system 100 consists of an extendable rod 1 10 which connects directly at the two ends thereof the two front wheel axle journals to each other by means of hinge means 1 1 1 equivalent to a spherical joint. The roll blocking is achieved by blocking the angle of rotation of the extendable rod 1 10 on the rolling plane at at least one end thereof by means of a dedicated actuator, such as a band brake or a drum brake 120 (as shown in Figure 2). The rod 1 10 so locked prevents the rolling movements of the two wheels. The roll block system may comprise two actuators, one at each of the two ends of the extendable rod 1 10. "Rolling plane" means a plane transverse to the longitudinal direction or direction of travel of the motor vehicle, and thus incident the centre line plane of the motor vehicle.

An alternative roll block system with respect to the particular one illustrated in Figure 2, but again described in Italian patent application no. 102015000088087, provides that the axle journals 50 of the two front wheels are connected to each other not by a single rod, but by two extendable rods so as to form an articulated quadrilateral system which is additional to the one forming the rolling kinematic mechanism. Blocking the roll is achieved by blocking the configuration of such an additional articulated quadrilateral (and therefore indirectly the rotation of each of the two rods with respect to the axle journals) by means of a mechanical clamp which is associated with one of the two extendable rods and acts on a brake disc sector fixed to the other extendable rod. The mechanical clamp can be operated in engagement on the disc sector to block the relative movements of the two extendable rods. Also in the rolling motor vehicle shown in Figure 3 and described in Italian patent application no. 102015000088090 (incorporated herein as a reference), the roll block system 100 consists of an extendable rod 1 10 which connects directly at the two ends thereof the two front wheel axle journals 50 - at the respective steering axes S-S - to each other by means of hinge means 1 1 1 equivalent to a spherical joint. In this case, the rolling block is achieved by blocking the length of the extendable rod 1 10 by means of a brake calliper 122 acting on the two telescopically associated portions 1 12 and 1 13 of the rod 1 10 itself.

In the rolling motor vehicle shown in Figure 4 and described in Italian patent application no. 102015000088097 (incorporated herein as a reference), the roll block system 100 consists of a rod 1 10 which connects directly at the two ends thereof the two front wheel axle journals 50 - at the respective steering axes - to each other by means of hinge means equivalent to a spherical joint. In this case, the rod 1 10 is not an additional element dedicated solely to the rolling block, but consists of the horizontal steering bar of the steering system. The steering bar is in turn hinged to a steering column 300 at an intermediate point between its two ends so as to oscillate with respect to the steering column 300 about a rotation axis Z-Z substantially orthogonal to a rolling plane of the two front wheels. The roll block is achieved by blocking the rotation of the steering bar 1 10 by a dedicated actuator, for example, a band brake, a drum brake or a disc brake 120, as shown in Figure 4.

In the solutions illustrated in Figures 2 and 4, the suspensions 90 are associated externally with the rolling kinematic mechanism 20, while in the solution illustrated in Figure 3 the suspensions 90 are integrated into the uprights 48 of the articulated quadrilateral forming the rolling kinematic mechanism 20.

The roll block systems described above are only exemplary. In general, the roll block system 100 of the two front wheels 10', 10", which operates directly or indirectly on the above rolling kinematic mechanism 20, can have any configuration as long as it is functional to the rolling block.

* * *

According to a general embodiment of the present invention, the method of contrasting the jumping triggered by a resonance oscillation in a motor vehicle with three or four wheels comprises the following operating steps:

- a) detecting a resonance oscillation which is triggered while driving the motor vehicle and generates an alternate jumping of the rolling kinematic mechanism 20, wherein said step a) of detecting generates selectively: an active resonance signal related to the presence of resonance oscillations of rolling kinematic mechanism 20; and a passive resonance signal related to the non-presence of resonance oscillations of rolling kinematic mechanism 20; - b) actuating the roll block system 100 (during the movement of the motor vehicle) in presence of said active resonance signal;

- b') keeping said roll block system 100 neutral in presence of said passive resonance signal. The step of actuating the roll block system (100) is suitable to damp the resonance oscillations resulting in a progressive damping of the alternate jumping of the rolling kinematic mechanism 20 and thus of the front wheels 10', 10", until annulling said oscillations.

Advantageously, the detection of a resonance oscillation can be carried out within predetermined frequency intervals, since the resonance oscillations of the rolling kinematic mechanism 20 have a specific own motion and therefore specific frequencies.

Advantageously, it is provided for a step of generating an active resonance signal following said detection step a), wherein in the presence of said active resonance signal said actuating step b) is activated.

By active resonance signal it is meant a signal that detects the presence of the resonance phenomenon on the rolling kinematic mechanism or on the front wheels.

Therefore, the step of actuating the roll block device is carried out in feedback in the presence of such an active resonance signal. The specification of how the signal is filtered is described in detail hereafter.

Preferably, said actuating step b) is prolonged for the entire period of time during which said active resonance signal detected in the detection step a) persists, so that the detection step a) and the actuating step b) are repeated as long as the active resonance signal persists in order to achieve a complete damping of the resonance oscillation of the rolling kinematic mechanism 20. When the resonance oscillation has been damped, the detection step provides a monitoring step as described in detail below.

Advantageously, the actuation step is performed intermittently, and is preferably prolonged for as long as the detection of such resonance oscillation persists.

Operationally, the intermittent blocking of rolling by means of the above block system stops the oscillations of the rolling kinematic mechanism 20 generated by the resonance oscillation with a consequent progressive damping of the alternating jumping of the front wheels 10', 10" caused by such oscillations.

The intermittent operation of the roll block system allows not to overload the driving of the motor vehicle, and thus not to worsen the driving feeling.

In particular, the intermittent actuation of the block system 100 only causes a slowing of the rolling movements, so as to interfere as little as possible with the driving action of the motor vehicle itself.

Due to the present invention, unlike what is contemplated in the prior art, it is therefore possible to intervene after the onset of a resonance of the rolling kinematic mechanism and consequent triggering of an alternating jumping of the front wheels, thus dampening such a jumping phenomenon before it assumes an intensity such as to cause the loss of control of the motor vehicle.

Preferably, as shown schematically in Figure 4, the step a) of detecting is obtained by at least one sensor 81 , 82 arranged on the rolling kinematic mechanism 20 and/or on the front wheels 10', 10".

Preferably, the above step a) comprises a step c) of monitoring the vibratory phenomena of the front wheels 10', 10" and/or of the rolling kinematic mechanism 20, and possibly also on the suspensions 90, in order to monitor the onset and the development over time of the

above resonance oscillation of the rolling kinematic mechanism 20 during the movement of the motor vehicle.

Operatively, the sampling frequency of the monitoring action must be such as to ensure statistically an intervention of the roll block system in the initial triggering steps of any resonance oscillations.

Preferably, the above step c) of monitoring is carried out continuously during the movement of the motor vehicle. In this way it is possible to more easily ensure that the detection of a possible resonance oscillation occurs temporally as close as possible to the moment of the onset of such phenomenon and it is therefore possible to brake the oscillations of the rolling kinematic mechanism 20 (generated by the above resonance oscillation) when they still have a limited amplitude with an alternating jumping of the wheels still small and therefore still controllable by the driver. Moreover, the damping of these oscillations will be more effective and faster.

In particular, "continuous" monitoring means a monitoring conducted with a time sampling frequency of signal acquisition (detection) at least twice the frequency of the resonance oscillation, which has a typical frequency of about 10Hz.

According to a preferred embodiment of the method according to the invention, the above step c) of monitoring comprises at least one of the following sub-steps:

-c1 ) measuring the oscillations on the front wheels 10', 10" by means of sensors 81 associated to the front wheels 10', 10"; and

-c2) measuring the oscillations on the rolling kinematic mechanism 20 by means of sensors

82 associated with the rolling kinematic mechanism (20).

In particular, the monitoring step c) can comprise both sub-steps c1 ) and c2).

The above sensors 81 , 82 are suitable to generate corresponding response signals 81 a and 82a.

The above step c) also comprises a sub-step d) of processing the signals generated by the above sensors 81 and/or 82 applying a predefined filtering logic in order to distinguish between vibratory phenomena correlated with resonance oscillations of the rolling kinematic mechanism and vibratory phenomena not related to resonance oscillations of the rolling kinematic mechanism.

In particular, wherein the above step d) of processing the above response signals 81 a, 82a applies a predefined filtering logic to distinguish between the above active resonance signal related to the presence of resonance oscillations of the rolling kinematic mechanism 20 and a passive resonance signal related to the absence of resonance oscillations of the rolling kinematic mechanism 20.

Preferably, the sub-steps c1 ) and c2) of measuring the oscillations are conducted with a time sampling frequency of signal acquisition at least greater than 20 Hz, and preferably from 50 and 100 Hz, and even more preferably greater than 100 Hz.

The fact that the system has the ability to distinguish between vibratory phenomena correlated with resonance oscillations of the rolling kinematic mechanism and vibratory phenomena not correlated to resonance oscillations of the rolling kinematic mechanism is not essential for contrasting the jumping, but is wholly preferable for the efficiency of the system as a whole. Without this capacity, the system would also intervene in situations of resonance of the forecarriage triggered by normal operation, due for example to the fact that the motor vehicle is traveling on a stretch of uneven road.

Advantageously, the sensors 81 , 82 associated to the front wheels 10', 10" and/or to the rolling kinematic mechanism 20 comprise at least one sensor chosen from:

- an accelerometer;

- an angular potentiometer placed between the rolling kinematic mechanism 20 and the frame 16 to check the roll and associated with linear and/or angular displacement sensors; and

- a combination thereof.

Preferably, the sensors 81 associated to the front wheels 10', 10" comprise at least one accelerometer for each front wheel.

In particular, it is possible to provide an embodiment in which an accelerometer and an angular potentiometer are associated to each front wheel 10', 10". The angular potentiometer is placed between the rolling kinematic mechanism 20 and the frame 16 to check the roll and is associated with linear and/or angular displacement sensors.

According to a completely preferred embodiment of the method according to the invention, the monitoring step c) comprises a sub-step c3) of measuring the oscillations of the suspensions 90 of the two front wheels by means of sensors 83 associated with the suspensions 90. This sub-step c3) is implemented in combination with at least one of the sub-steps c1 )-c2).

Preferably, the sensors 83 associated with the suspensions 90 comprise a position sensor. As already discussed, generally the vibratory phenomena correlated to resonance oscillations of the rolling kinematic mechanism (and therefore potentially capable of

triggering dangerous jumping phenomena) are never accompanied by compression of the suspensions.

Preferably, in the steps c1 )-c2) of processing of the signals generated by the sensors 81 , 82 associated with the front wheels 10', 10" and/or with the rolling kinematic mechanism 20, a filter logic based on the behaviour of the suspensions in concomitance with resonance oscillations of the rolling kinematic mechanism may be adopted.

In more detail, as a filtering logic, a logic can be adopted that classifies those vibratory phenomena coupled with suspension compression as not related to resonance oscillations of the rolling kinematic mechanism.

Preferably, said processing sub-step d) is conducted by acquiring the signals generated in at least one of the sub-steps c1 )-c2) and the signals generated by the detection sensors 83 of the oscillations of the suspensions in the sub-step c3) and implementing said filtering logic. The above predefined filtering logic classifies as non-correlated to resonance oscillations of the rolling kinematic mechanism those vibratory phenomena coupled to suspension compression.

Therefore, sub-step c3) per se is not able to detect the resonance oscillation, because the suspensions do not work when it occurs.

The sub-step c3) serves, on the other hand, correlated to the signals of the detection steps on the wheels and/or the rolling kinematic mechanism, to distinguish the presence or absence of the resonance phenomenon.

Preferably, the roll block system 100 of the two front wheels 10', 10" which operates directly or indirectly by blocking the rolling kinematic mechanism 20 comprises devices adapted to exert a continuous and non-discrete blocking action of the rolling kinematic mechanism 20. In particular, devices capable of exerting a continuous and non-discrete blocking action are, in general, blocking devices which operate by friction, in particular disc brakes, drum brakes or tape brakes.

On the contrary, devices capable of exerting a discrete blocking action are all the blocking devices based on the shape coupling, in particular ratchet or gear systems. Such devices are less effective in contrasting resonance oscillation phenomena, since in order to function effectively they require that the two parts to be mutually blocked are not substantially subject to relative movements, but are essentially stationary. This does not occur if a wheel enters in resonance. In this case, for the weights and damping involved there is a frequency of an order of magnitude greater than 10 HZ and the components of the roll block system would

be subject to fast relative movements. This would in fact prevent or at least make the intervention of the ratchet or gear locking systems difficult.

Preferably, the step b) of intermittently actuating the roll block system 100 is carried out according to a predefined scheme of intervention based on a modulation of the blocking frequency.

Advantageously, the predefined intervention scheme may be based on a modulation of the frequency and intensity of blocking.

Operatively, as already mentioned, the actuation of the roll block system 100 in step b) is modulated in frequency, and possibly also in intensity, so as not to lead to a complete blockage of the roll while driving the motor vehicle. The intermittent actuation of the blocking system 100 in fact has an effect only of slowing down the roll movements in order to maintain substantially unchanged the driving dynamics of the motor vehicle itself.

Advantageously, depending on the type of roll block system 100, different operating strategies can be adopted in the modulation of the blocking frequency, and possibly also of the blocking intensity.

For example, in the case where the block system consists of a disc sector plus clamp (as in the case illustrated in the motor vehicle example illustrated in Figure 4) and the clamp is mechanically operated (for example by means of a metal cable), the clamp can be controlled at successive instants, for example, with a pwm (pulse width modulation) control in such a way that the succession of blocks still allows the rolling of the vehicle. A prolonged block of the rolling would in fact lead to a loss of control of the trajectory imposed by the driver. This control strategy can also be adopted in other block systems, for example consisting of tape or drum brakes, mechanically operated by means of metal cables.

If the block system is operated hydraulically, the damping can be introduced by partializing the oil passages without reaching a complete system block.

Preferably, as illustrated schematically in Figure 4, the method of contrasting the jumping according to the present invention is implemented in a completely automatic way by an electronic control unit 80 of the motor vehicle.

In particular, both step a) of detection and step b) of actuation of the roll block system 100 are implemented and performed automatically by program means loaded on said electronic control unit 80 for controlling the motor vehicle.

In particular, step c) of monitoring the vibratory phenomena of the front wheels and/or the rolling kinematic mechanism is automatically implemented, with the relative sub-steps:

-c1 ) measuring the oscillations on the front wheels 10', 10" by means of sensors 81 associated to the front wheels 10', 10";

-c2) measuring the oscillations on the rolling kinematic mechanism 20 by means of sensors 82 associated with the rolling kinematic mechanism (20); and

- d) processing the signals generated by the above sensors 81 applying a predefined filtering logic in order to distinguish between vibratory phenomena correlated with resonance oscillations of the rolling kinematic mechanism and vibratory phenomena not related to resonance oscillations of the rolling kinematic mechanism.

- c3) continuously measuring the oscillations of the suspensions of the two front wheels by means of sensors associated with the suspensions,

or a combination of steps c1 ) - c3).

In detail, the sub-step c3) of providing sensors on the suspensions must be integrated with one of the two sub-steps.

According to an alternative and not preferred embodiment of the method according to the invention, only the detection step a), and in particular the step c) of monitoring the vibratory phenomena of the front wheels and/or of the rolling kinematic mechanism (with the relative sub-steps c1 ), c2) and c3) and)), is carried out automatically by the electronic control unit 80 of the motor vehicle, while the step b) of intermittent actuation of the roll block system 100 is assigned to the intervention of the driver as a response to the generation of the active resonance signal which detects the occurrence of a resonance oscillation by the electronic control unit 80. In this case, - in a first configuration - the active resonance signal will activate a special sound and/or light signalling device (for example, a warning light on the dashboard) and by a manual command to activate the roll block system 100, the driver can control the execution of an intermittent actuation, for example a button. Preferably, the actuation of the roll block system in the intermittent version is in any case managed automatically by the electronic control unit 80 of the motor vehicle, which will define the frequency and/or the intensity of the roll block.

According to a further alternative and not preferred embodiment of the method according to the invention, also step a) of detecting the resonance oscillation is carried out by the driver, who according to his sensitivity decides if and when to execute step b) of intermittent actuation of the roll block system 100.

In this case, the system will not generate the active resonance signal but it will be the same driver who on the basis of his sensitivity while driving will recognize a resonance oscillation and will activate the block system by a button in order to dampen it.

Compared to a manual actuation by the driver (for example, following the activation of a sound and/or light alarm on the dashboard that signals the triggering of a dangerous resonance oscillation of the rolling kinematic mechanism, or on the evaluation of the driver himself), a fully automatic drive ensures faster and safer operation. The method according to the invention provides, in fact, that the operation of the roll block system takes place during the vehicle travel, possibly even at high speeds, and with specific times and modes. An automatic control of the times and of the operating modes is therefore completely preferable to ensure not only an effective intervention efficiency, but also the safety of the driver.

Advantageously, the automatic actuation of the roll block system for anti-jumping purposes can however be signalled to the driver by means of a light and/or sound signal (for example, a warning light on the dashboard) similar to the ABS or ASR systems to indicate the management of a potential danger.

From what has been said above, the method of contrasting the jumping according to the invention is based on the introduction of a damping on the mechanism which ensures the rolling of the motor vehicle in order not so much to avoid the onset of resonance, but to damp it as soon as triggered, before it turns into a dangerous alternating jumping of the wheels. The intervention strategy can be applied in general on any rolling motor vehicle provided with a roll block system and therefore does not depend on the rolling kinematic mechanism or the roll block system.

In particular, as already described above, the method according to the invention can be applied to a three or four-wheeled rolling motor vehicle in which the rolling kinematic mechanism 20 consists of an articulated quadrilateral system.

The roll block system 100 of the two front wheels 10', 10" can operate directly on the rolling kinematic mechanism 2 (as in the motor vehicle illustrated in Figure 1 ). In this case, the roll block system 100 comprises releasable means for blocking the configuration of the articulated quadrilateral system, which in the example of Figure 1 consist of a disc brake 101 , 102.

For the purposes of the present invention, in the motor vehicle in Figure 1 the roll block which operates in parallel on the shock absorbers does not affect the jumping and may not be used, since only the mechanical part which acts on the disc brake is sufficient.

More in detail, in the motor vehicle illustrated in Figure 1 , the roll block system comprises a stepper electric motor which, by means of a metal cable, actuates the mechanical clamp 101 on the disc sector 102 which blocks the articulated rolling quadrilateral. In parallel, the stepper electric motor also actuates a pump of a hydraulic circuit which actuates the two

clamps which block the rods 103 placed in parallel with the shock absorbers 200. The mechanical irreversibility, fundamental to ensure that the block remains active during the long stop without using battery voltage, is given by the low mechanical efficiency of the gears which multiply the torque of the electric motor. Also the electric parking clamps of cars are provided with mechanical irreversibility to ensure that the car can remain braked when parked even with low battery.

As previously described in relation to the implementation of the method of contrasting the jumping according to the invention, in the specific case of the motor vehicle illustrated in Figure 1 it would be sufficient to operate on the disc-brake system 101 , 102 which frictionally blocks the quadrilateral. For the purposes of the present invention, however, it is not necessary to inhibit the operation of the parallel block on the shock absorbers, acting on the hydraulic circuit. Such inhibition would not cause problems, but it would be useless, since in the event of an alternating jumping of the wheels (as already highlighted) the shock absorbers do not intervene.

More specifically, for the implementation of the method according to the invention, the motor vehicle illustrated in Figure 1 may be provided with a control unit which directly actuates the stepper motor by modulating the pads on the disc. This can be done by operating at intervals and/or by not tightening the disc completely between the brake linings. The aim is in fact to introduce a damping which, if it cannot be of the viscous type (therefore dependent on the speed obtained in the shock absorbers), can be at least Coulumbian, i.e. friction, or position dependent, as for all types of brake.

According to an alternative and preferred embodiment of the invention, the roll block system 100 of the two front wheels 10', 10" can operate indirectly on the rolling kinematic mechanism 20 (as in the motor vehicles shown in Figures 2, 3 and 4).

In this case, preferably, as provided for in the motor vehicles shown in Figures 2, 3 and 4 and as already described above, the roll block system 100 comprises a second kinematic mechanism 1 10 which directly connects the two front wheels 10', 10" with each other at the respective axle journals 50 by means of hinging means and is susceptible of assuming at least two different configurations:

- a free configuration, wherein such a second kinematic mechanism 1 10 follows passively and transparently with respect to the driving dynamics the movements of the two wheels 10', 10" with each other and with respect to the forecarriage frame 16; and

- a blocked configuration, wherein such a second kinematic mechanism 1 10 blocks the angle formed by a lying plane of at least one wheel with respect to the ground. In particular, such a lying plane is orthogonal to the rotation axis R-R of the wheel itself.

This second mechanism may comprise one or more extendable rods connected at the ends to the axle journals 50 of the two front wheels and releasable means for locking the length of the extendable rods or the angle of rotation of said rods with respect to the front wheel axle journals.

In the case where the roll block system comprises actuators (drum or tape brakes) at both ends of the rods for blocking the rotation of the rods, for the purposes of the present invention, only one of these actuators may be actuated, duplication being a redundant element for the purpose of blocking the rolling.

The axle journal 50 of each wheel is mechanically connected to a rotation pin 51 of the wheel so as to support it rotatably around an axis of rotation R-R. The motor vehicle comprises suspension means 90 to guarantee each axle journal 50 at least one spring suspension movement with respect to the above rolling kinematic mechanism 20.

In particular, as provided in the motor vehicle illustrated in Figure 3, the suspensions 90 can be integrated into the uprights 48 of the articulated quadrilateral forming the rolling kinematic mechanism 20.

For the purpose of implementing the method of contrasting the jumping according to the invention, a roll block system which indirectly operates on the rolling kinematic mechanism by working on the wheel axle journals is preferable, since it allows intervening closer to the source of the jumping. The contrast of the jumping is therefore potentially more rapid and effective.

The present invention concerns also a system for contrasting the jumping triggered by a resonance oscillation in a motor vehicle with three or four wheels.

Said motor vehicle comprising: - a forecarriage frame 16; - at least a pair of front wheels 10', 10" kinematically connected to each other and to the forecarriage frame 16 by means of a rolling kinematic mechanism 20; - a roll block system 100 suitable to block the rolling of the two front wheels 10', 10", wherein said roll block system 100 acts directly or indirectly on said rolling kinematic mechanism 20.

Said system comprising programme means configured to:

- a) detecting a resonance oscillation which is triggered while driving the motor vehicle and generates an alternate jumping of the rolling kinematic mechanism (20), wherein said step a) of detecting generates selectively: an active resonance signal related to the presence of

resonance oscillations of rolling kinematic mechanism 20, and a passive resonance signal related to the non-presence of resonance oscillations of rolling kinematic mechanism 20;

- b) actuating said roll block system 100 in presence of said active resonance signal;

- b') keeping said roll block system 100 neutral in presence of said passive resonance signal. The step b) of actuating said roll block system 100 is suitable to damp the resonance oscillations resulting in a progressive damping of the alternate jumping of the rolling kinematic mechanism 20 and thus of the front wheels 10', 10", until annulling said oscillations.

The invention allows several advantages to be achieved, some of them already described. The method according to the present invention, unlike what is contemplated in the prior art, allows intervening after the onset of a resonance of the rolling kinematic mechanism and consequent triggering of an alternating jumping of the front wheels, thus dampening such a jumping phenomenon before it assumes an intensity such as to cause the loss of control of the motor vehicle.

The method of contrasting the jumping triggered by a resonance oscillation in a three or four-wheeled rolling motor vehicle according to the invention is furthermore operationally reliable and easy to implement, since in the intervention step it is based on roll block devices with which rolling motor vehicles are generally already provided.

The invention thus conceived thus achieves the intended purposes.

Of course, it may take, in its practical embodiment, also shapes and configurations other than the above without departing from the present scope of protection.

Furthermore, all details may be replaced with technically equivalent elements and dimensions, shapes and materials used may be any according to the needs.