Patent Description:
In the field of motor vehicles there is an increasing offer of vehicles that combine the features of two wheeled saddle vehicles (motorcycles and scooters, for example) in terms of handling, with the stability of four wheeled vehicles. These vehicles include three wheeled motor vehicles provided with two front steered wheels and one rear driving wheel, and four wheeled motor vehicles, typically referred to as QUAD bikes.

More in detail, the aforesaid three wheeled motor vehicles are provided with two front steered wheels, i.e., adapted to steer the vehicle controlled by the rider by means of the handlebar, and rolling, i.e., laterally tiltable with a rolling movement. The rolling movement is an tilting movement about an axis substantially oriented in the direction of movement. Three wheeled vehicles further comprise a rear driving wheel, mechanically connected to the motor and having the purpose of providing the torque and hence of allowing traction, while the paired front wheels have the purpose of providing the directionality of the vehicle.

In addition to the steering movement, the paired front wheels are provided with a rolling movement and are connected to the vehicle frame by means of shock absorber suspensions, which allow a springing movement. As a result of the use of two paired front wheels, a rolling vehicle has, with respect to a motor vehicle with only two wheels, greater stability guaranteed by the double contact of the front wheels with the ground, similarly to that provided by a car.

The front wheels are connected to each other by means of mechanisms that allow the wheels to roll and steer substantially synchronously, for example through the interposition of one or two four bar linkages that connect the front wheels to a forecarriage frame. These motor vehicles are also frequently provided with two separate shock absorber suspensions, one for each front steered wheel. Each suspension has an elastic element (spring) and a viscous element (shock absorber).

Although three or four wheeled rolling motor vehicles have high stability, in certain conditions they can fall over due to an uncontrolled rolling movement. This can occur in particular when moving forward at low speed, or when the vehicle is stationary or parked. To prevent this problem, three and four wheeled tilting motor vehicles are often provided with a roll-blocking or roll control system, which prevents the motor vehicle from accidentally falling over when stationary or moving forward at low speed. Three wheeled motor vehicles with roll-blocking or roll control system are for example disclosed in <CIT> and in <CIT>.

<CIT>, in particular, discloses a three wheeled tilting vehicle, with a forecarriage having a four bar linkage with two superimposed cross members extending in a right-left direction and hinged centrally to the vehicle frame. The ends of the cross members are joined to each other by a left upright and by a right upright. Each upright is connected to a support arm of a respective front steered wheel. A suspension is interposed between each support arm and the respective front wheel.

The roll-blocking system comprises a gripper that blocks the four bar linkage with respect to the vehicle frame, preventing pivoting thereof. Moreover, the roll-blocking system comprises, for each suspension, a suspension locking member. The two suspension locking members and the gripper for blocking the linkage are controlled by a hydraulic actuator.

The roll-blocking system described above is safe and efficient. However, it is neither particularly compact nor inexpensive.

<CIT> discloses a tilting vehicle having two front steered wheels and a rolling four bar linkage corresponding to the preamble of claim <NUM>. Each front steered wheel has a respective suspension. The roll-blocking system is similar to the one disclosed in <CIT>.

<CIT> discloses a shock absorber having a bidirectional selective block used to block the rolling movement. The shock absorber comprises a main cylinder, having a piston sliding in the main cylinder. The piston divides the interior of the main cylinder in a first chamber and a second chamber. The first chamber is fluidly coupled with a secondary cylinder, parallel to the main cylinder, through a first duct. The second chamber is fluidly coupled to the secondary cylinder through a second duct. In the second cylinder a damping valve is arranged, comprising a stationary apertured plate, which controls the flow of incompressible viscous liquid from the first chamber to the second chamber and vice versa, through the first duct and the second duct as a consequence of the displacement of the piston in the main cylinder. In order to block the shock absorber a double valve is provided, which simultaneously closes both the first duct and the second duct, thus preventing fluid circulation through the stationary apertured plate.

This known system is efficient, but still has some drawbacks, in particular in relation to the overall size. Moreover, the system of the current art requires two cylinders arranged side-by-side and of the same length, which increases the cost of the device and places some limitations to the suspension design, in particular having regard to the position of the spring.

It would be useful to have a roll-blocking system which is equally effective, but which overcomes the problems of prior art devices. In particular, a roll-blocking system that requires a smaller number of actuators and is therefore simpler, less costly and more compact would be useful.

To solve or limit one or more of the problems of rolling motor vehicles of the current art, a rolling motor vehicle according to claim <NUM> is provided. The dependent claims concern further features and embodiments of the vehicle according to the invention.

The motor vehicle comprises a four bar linkage with cross members extending in a right-left direction with respect to a median plane of the motor vehicle, and support arms of the two front steered wheels, with which respective suspensions are associated. The leaning movement (rolling movement) of the motor vehicle causes deformation of the four bar linkage. The motor vehicle comprises a roll-blocking system of the rolling movement, which in turn comprises a four bar linkage locking device and a locking device of the suspension of the two front steered wheels.

Advantageously, the suspension locking device comprises, for each of said suspensions, a valve adapted to at least partially close a duct connecting a chamber of a cylinder of the shock absorber, inside which a piston of the shock absorber slides, and a tank, preventing the flow of viscous fluid between the chamber and the tank.

In the present context the term "block/lock", referring to the movement of the four bar linkage or to the movement of the suspensions must be understood in the sense of also comprising a controlling action that limits these movements. For example, as the movement of the suspensions is blocked by means of a valve that prevents the passage of viscous fluid from a cylinder of the shock absorber to a tank, block is meant both as total closing of this passage and as a substantial reduction thereof. In this latter case, a limited capacity for movement of the suspensions remains, for example to allow springing of the front steered wheels when subjected to high stress.

Advantageously, in embodiments disclosed herein the valve is operated by an electrically controlled actuator. This simplifies control of the valve, which can be configured as a solenoid valve.

In advantageous embodiments, the roll-blocking system comprises, in addition to the suspension locking device, a four bar linkage locking device. This locking device can advantageously comprise a brake adapted to block the movement of the four bar linkage with respect to the frame. In advantageous embodiments, the brake comprises an electrically controlled electromechanical actuator, preferably comprising a non-reversible gear motor, i.e. which remains in active position, with the brake blocked, when the electric motor of the gear motor is switched off. In this way, the four bar linkage locking device remains active when the motor vehicle is switched off, without consuming electricity.

In advantageous embodiments, to obtain a compact and inexpensive structure, the brake of the four bar linkage locking device can comprise a gripper, an electric motor and a reduction gear, integrated in a single housing.

Further advantageous features of the motor vehicle of the present invention are described hereunder, with reference to some non-limiting exemplary embodiment, and in the accompanying drawings.

The invention will be better understood by following the description and the accompanying drawings, which illustrate a non-limiting example of embodiment of the invention. More in particular, in the drawing:.

<FIG> illustrates an axonometric view of a motor vehicle <NUM>, which comprises a roll-blocking system according to the present invention. The motor vehicle of <FIG> is illustrated with parts removed, for greater simplicity of representation. In particular, the casing, the saddle, the motor and the handlebar are omitted. In general terms, the roll-blocking system comprises a suspension locking device and a four bar linkage locking device.

In brief, the motor vehicle <NUM> comprises a frame <NUM>, a rear driving wheel <NUM>, mechanically connected to a motor (not shown) that supplies the torque, and a pair of front steered wheels. More in particular, the motor vehicle <NUM> comprises a first front steered wheel <NUM>', or left front steered wheel <NUM>', and a second front steered wheel <NUM>", or right front steered wheel <NUM>". Hereunder, components, assemblies or elements that are symmetrical with respect to a median plane of the motor vehicle <NUM> are indicated with the same reference numeral followed by an apostrophe (') for the elements on the left side of the median plane M, and by two apostrophes (") for the elements on the right side of the median plane M.

In the embodiment illustrated in <FIG>, the front part of the motor vehicle <NUM>, hereinafter also referred to as forecarriage, is provided with a steering mechanism, indicated as a whole with <NUM>, which allows the front steered wheels <NUM>' and <NUM>" to perform synchronous steering and rolling movements. In the present context, steering movement is meant as the movement of the front wheels <NUM>', <NUM>" about respective steering axes. By means of the steering movement a variation in the trajectory is imparted to the motor vehicle <NUM> with respect to a rectilinear trajectory in forward direction. In the present context, rolling movement means the movement that allows the motor vehicle <NUM> to tilt with respect to a vertical plane, for example when the vehicle travels around a bend.

In the illustrated embodiment, the steering mechanism <NUM> comprises a four bar linkage <NUM>, more specifically an parallelogram four bar linkage, hereinafter indicated as rolling four bar linkage <NUM>. The rolling four bar linkage <NUM> has a first upper cross member <NUM> and a second lower cross member <NUM>, substantially parallel to each other. The upper cross member <NUM> and the lower cross member <NUM> extend according to the left-right direction, transversely to the median plane.

The two cross members <NUM>, <NUM> are hinged to the frame <NUM> in two intermediate points by means of hinges 13A and 15A, respectively. In this way, the two cross members <NUM> and <NUM> can rotate about respective rotation axes parallel to each other and lying on the median plane M of the frame <NUM> of the vehicle <NUM>, to perform a rolling movement, for example when the motor vehicle <NUM> travels around a bend at speed.

The rolling four bar linkage <NUM> further comprises two uprights, respectively a left upright <NUM>' and a right upright <NUM>". The two uprights <NUM>', <NUM>" are hinged to the upper cross member <NUM> and to the lower cross member <NUM> to form therewith the rolling four bar linkage. The reference numerals <NUM>', <NUM>' and <NUM>", <NUM>" indicate hinges on the two sides of the vehicle <NUM>, by means of which the uprights <NUM>' and <NUM>" are hinged to the cross members <NUM>, <NUM>. More in particular, the upper cross member <NUM> is hinged at a first (left) end by means of the hinge <NUM>' to the left upright <NUM>' and at a second (right) end by means of the hinge <NUM>" to the right upright <NUM>". Likewise, the lower cross member <NUM> is hinged at a first (left) end by means of the hinge <NUM>' to the left upright <NUM>' and at a second (right) end by means of the hinge <NUM>" to the right upright <NUM>". The hinges <NUM>', <NUM>" and <NUM>', <NUM>" define mutual rotation axes of the cross members <NUM>, <NUM> and of the uprights <NUM>', <NUM>". The rotation axes defined by the hinges <NUM>', <NUM>" and <NUM>', <NUM>" are parallel to the rotation axes of the cross members <NUM>, <NUM> with respect to the frame <NUM>.

, In addition to the rolling four bar linkage <NUM>, the steering mechanism <NUM> comprises a pair of support arms, to which the front steered wheels <NUM>', <NUM>" are connected. More precisely, a left support arm <NUM>' supports the left front steered wheel <NUM>' and a right support arm <NUM>" supports the right front steered wheel <NUM>".

In the illustrated embodiment, the two support arms <NUM>', <NUM>" are structured as half forks, but it must be understood that other configurations are possible. Each support arm <NUM>', <NUM>" is connected to the rolling four bar linkage <NUM> so as to be able to rotate about a respective steering axis.

In the illustrated embodiment, each support arm <NUM>', <NUM>" is housed at the top inside the respective upright <NUM>', <NUM>" of the rolling four bar linkage <NUM>. For this purpose, the two uprights <NUM>', <NUM>" can be formed with a hollow cylindrical body, inside which bearings(not shown) of the support arms <NUM>' <NUM>" of the wheels <NUM>', <NUM>" are mounted.

To control the steering movement of the two support arms <NUM>', <NUM>" about the steering axes, a transverse component <NUM> extending in a right-left direction is provided. In the embodiments illustrated herein, the transverse component <NUM> forms a steering bar, i.e., a bar that transmits the steering movement from the steering column to the two support arms <NUM>', <NUM>" and hence to the two front steered wheels <NUM>', <NUM>". Hereunder the transverse component <NUM> will therefore be referred to as steering bar <NUM>.

The steering bar <NUM> is movable controlled by a steering column <NUM> operated by means of a handlebar (not shown) of the motor vehicle <NUM>. The steering column <NUM> is connected in a central point to the steering bar <NUM>, by means of a transmission <NUM>. Rotation of the handlebar <NUM> about the axis of the steering column <NUM> causes the translation of the steering bar <NUM>. The steering bar <NUM> is connected by means of end couplings to the two support arms <NUM>', <NUM>" of the front steered wheels <NUM>', <NUM>", which rotate simultaneously about the steering axes when the bar translates as a result of the control imparted by the handlebar and by the steering column <NUM>. Vice versa, a tilting, i.e., rolling, movement of the motor vehicle <NUM>, schematically indicated by the double arrow R in <FIG>, causes a rotation of the steering bar <NUM> with respect to the support arms <NUM>', <NUM>" about respective rolling axes.

In general, rolling and steering movements occur simultaneously during travel. When the motor vehicle <NUM> is stationary, as will be clarified hereunder, it is advisable to block the rolling movement, leaving the steering movement free and for this purpose the roll-blocking system, described in detail hereunder, is provided.

Each front steered wheel <NUM>', <NUM>" is connected to the respective support arm <NUM>', <NUM>" by means of a suspension, the left of which indicated with <NUM> is visible in <FIG>. The right suspension (which in <FIG> is covered by the wheel <NUM>") is symmetrical with respect to the left suspension. Each suspension connects the respective front steered wheel <NUM>', <NUM>" to the arm <NUM>', <NUM>" allowing the wheel to perform springing movements. In <FIG> the springing movement is indicated with f33 and involves a compression and extension of the suspension <NUM>. The front steered wheel <NUM>', <NUM>" is connected to the respective support arm <NUM>', <NUM>" by means of a rocker arm, indicated with <NUM> in <FIG> for the left front steered wheel <NUM>'. The rocker arm <NUM> is hinged to the respective support arm <NUM>' so as to pivot about a pivoting axis 35A. The distal end of the rocker arm <NUM> supports the hub <NUM> of the left front steered wheel <NUM>'. The right front steered wheel <NUM>" has a symmetrical suspension arrangement, not visible in <FIG> as covered by the wheel <NUM>".

To block the rolling movement of the motor vehicle <NUM> both the movement of the rolling four bar linkage <NUM>, and the springing movement of the suspensions <NUM> must be blocked.

To block the movement of the rolling four bar linkage <NUM> a four bar locking device is provided. In some currently preferred embodiments, the four bar linkage locking device comprises a brake <NUM>, carried by the frame <NUM> of the motor vehicle <NUM>. In some embodiments the brake <NUM> comprises a gripper <NUM> with an actuator, for example electromechanical, electromagnetic or hydraulic, schematically indicated with <NUM>. The gripper acts on a disc sector <NUM> rigidly connected to one of the components of the rolling four bar linkage <NUM>. In the illustrated embodiment the disc sector <NUM> is rigidly connected to the lower cross member <NUM> of the rolling four bar linkage <NUM>.

When the brake <NUM> is activated, the gripper <NUM> blocks the disc sector <NUM> and thus prevents the rolling movement of the rolling four bar linkage <NUM> with respect to the frame <NUM> of the motor vehicle <NUM>.

<FIG> shows a side view of the brake <NUM> with the gripper <NUM>. In the illustrated embodiment, the gripper <NUM> is operated by an electric motor <NUM>, associated with which is a reduction gear <NUM> that transmits the rotary motion of the electric motor <NUM> to a brake jaw <NUM> that co-acts with a brake jaw <NUM>. The two brake jaws <NUM> and <NUM> act on opposite faces of the disc sector <NUM> to brake it. The gripper <NUM> can be floating so that by moving the jaw <NUM> against the disc sector <NUM> by means of the electric motor <NUM>, a pressure of the opposite jaw <NUM> is also obtained. The reduction gear <NUM> is advantageously non-reversible, in the sense that once the gripper <NUM> of the brake has been closed by means of the motor <NUM>, the gripper remains blocked even with the motor switched off. Opening of the gripper requires activation of the motor <NUM> in the reverse direction.

Advantageously, as can be seen in <FIG>, the gripper <NUM> with the actuator, comprising the electric motor <NUM> and the reduction gear <NUM>, is formed as an integrated component, where a same housing contains the electric motor <NUM>, the reduction gear <NUM>, and the jaws <NUM> and <NUM> of the gripper.

The arrangement illustrated in <FIG> is particularly advantageous as it gives rise to a very compact and low cost four bar linkage locking device.

To block the springing movement of the suspensions a suspension locking device is provided. In the embodiment described herein, the suspension locking device uses a particular configuration of the hydraulic shock absorber of each of said suspensions. <FIG> shows a section according to a longitudinal plane of an exemplary embodiment of a suspension <NUM> that can be used to block the springing movement.

The suspension <NUM> comprises a shock absorber <NUM> and an elastic element <NUM>, for example a coil spring. In the illustrated embodiment the shock absorber <NUM> comprises a cylinder <NUM>, internally divided into a first chamber <NUM> and a second chamber <NUM> by a sliding piston <NUM> housed in the cylinder <NUM>. The piston is connected to a rod <NUM> that extends through the chamber <NUM>. The chambers <NUM> and <NUM> are filled with a viscous fluid, typically oil. The cylinder <NUM> and the piston <NUM> of the shock absorber <NUM> are connected to two elements that must move with respect to each other to follow the springing movement. In the illustrated example, the rod <NUM> of the piston <NUM> is fixed to a connection block <NUM>, by means of which the suspension <NUM> is constrained to the rocker arm <NUM> or other element that follows the springing movement of the respective front steered wheel <NUM>' or <NUM>". The head 54A of the cylinder <NUM> is fixed to the support arm <NUM>' or <NUM>" of the respective front steered wheel <NUM>' or <NUM>".

The piston <NUM> of the shock absorber <NUM> has flow orifices or passages 59A that connect the chambers <NUM> and <NUM> into which the piston <NUM> internally divides the cylinder <NUM>. In the embodiment flow orifices through the piston <NUM> are provided.

The compression and extension movement of the suspension <NUM> causes a compression and extension of the spring <NUM> and a sliding of the piston <NUM> according to the double arrow f59 with retraction and extraction of the rod <NUM>. The damping effect of the springing movement provided by the shock absorber <NUM> is obtained as a result of the resistance offered by the flow orifices 59A to the outflow of oil from one to the other of the chambers <NUM> and <NUM>.

When the piston <NUM> slides in the cylinder <NUM>, a variable length of the rod <NUM> partially occupies the volume of the chamber <NUM>, reducing or increasing the total volume available for the oil inside the cylinder <NUM>, i.e., of the two chambers <NUM> and <NUM>. Therefore, when the piston <NUM> moves away from the head 54A of the cylinder causing an increase in the volume of the chamber <NUM> and a reduction in the volume of the chamber <NUM>, oil flows from the chamber <NUM> to the chamber <NUM> through the flow orifices 59A. However, as a part of the volume of the chamber <NUM> is occupied by the rod <NUM>, the amount of oil that flows from the chamber <NUM> into the chamber <NUM> as a result of the reduction in the volume of the chamber <NUM> is less than the increase in the volume available for the oil in the chamber <NUM>. The opposite occurs when the piston <NUM> slides in the cylinder <NUM> toward the head 54A of the cylinder, reducing the volume of the chamber <NUM> and increasing the volume of the chamber <NUM>. In this case the reduction in the volume of the chamber <NUM> tends to expel a volume of oil from the chamber <NUM> that is greater than the volume that can be received in the chamber <NUM>.

To offset this difference between the volume made available for the oil in one chamber and the volume of oil expelled from the other, the chamber <NUM> is in fluid communication with a third chamber or tank <NUM>, which forms an auxiliary tank for the viscous fluid of the shock absorber <NUM>. A part of the tank <NUM> is occupied by a compressible volume <NUM>, for example containing gas. The compressible volume <NUM> can be separated from the oil contained in the tank <NUM> by means of a movable or deformable component. In the illustrated example, the separation between the oil (or other incompressible viscous fluid) and the gas (compressible fluid) is provided by a deformable diaphragm <NUM>, for example made of rubber. In other embodiments the tank <NUM> can be divided into two volumes by a piston or rigid moving diaphragm.

The tank <NUM> and the first chamber <NUM> are connected to each other by means of a duct <NUM> in which a valve <NUM> is arranged, which divides the duct into two portions 71A and 71B. In some embodiments, more than one duct can be provided in parallel, in which case one or more valves are provided to selectively open and close all the ducts that connect the first chamber <NUM> to the tank <NUM>. The valve can be controlled by an actuator <NUM>, for example of electric or electromagnetic type.

During normal operation of the motor vehicle <NUM>, when the rolling movement and the springing movement must be free, the valve <NUM> is held by the actuator <NUM> in an open position. In this way an oil, or other incompressible viscous fluid, can flow out of the first chamber <NUM> into the tank <NUM> and vice versa, in order to offset the variation in the total volume of oil contained in the cylinder <NUM>. More in particular, when the suspension <NUM> contracts and the rod <NUM> penetrates the cylinder <NUM>, a part of the oil flows out of the first chamber <NUM> into the tank <NUM>. The compressible volume <NUM> is reduced. Vice versa, when the rod <NUM> exits from the cylinder <NUM>, increasing the volume inside the cylinder <NUM> that must be occupied by the oil, an amount of oil flows through the duct <NUM> out of the tank <NUM> into the first chamber <NUM>.

When the suspension locking device requires to be activated, the actuator <NUM> operates the valve <NUM>, closing the duct <NUM>, so that oil can no longer flow out of the first chamber <NUM> into the tank <NUM> and vice versa. A compression of the suspension <NUM> is not possible, as oil cannot be expelled from the cylinder <NUM> to create the additional volume that should be occupied by the rod <NUM> that penetrates the cylinder <NUM>. An extension movement (elongation) of the suspension <NUM> is not possible as the greater volume made available by extraction of the rod <NUM> cannot be filled by oil coming from the chamber <NUM>.

Consequently, the movement of the piston <NUM> in the cylinder <NUM> is prevented and therefore in substance the springing movement of the suspension <NUM> is inhibited.

The actuator <NUM> can be an electromagnetic actuator, for example a solenoid.

In some embodiments, the actuator <NUM> can be a bi-stable actuator, i.e., provided with two stable positions, respectively open and closed.

In other embodiments, for reasons of safety the actuator <NUM> can be configured to be normally open and require an electrical control to close it. This ensures that in case of failure the valve remains open, preventing accidental or unwanted activation of the block of the springing movement of the suspension.

A single electrical control unit can control the entire roll-blocking system: the two actuators <NUM> that operate the valves <NUM> of the two suspensions <NUM>, and the actuator <NUM>. This provides a very simple configuration of the entire roll-blocking system, which is less costly, more compact and very reliable. When the motor vehicle <NUM> is stationary, or moving at very low speed, or when it is parked, the roll-blocking system can be activated, so that the motor vehicle can remain in an erect position, preventing rolling movements, i.e., tilting that could cause the motor vehicle <NUM> to fall over. When the motor vehicle is moving the roll-blocking system is deactivated and the motor vehicle <NUM> can perform normal rolling movements, for example on a bend. The electrical control unit can receive signals from numerous sensors of the vehicle, for example from the speed sensors of the front wheels and from the motor control unit. In particular, the motor control unit can provide the electrical control unit of the roll-blocking system with indications regarding opening of the throttle valve or of the number of revolutions of the motor. The electrical control unit is configured to process the signals of the sensors, and the signal coming from the handlebar control for blocking/releasing rolling operated by the driver, and to process an output signal that operates said roll-blocking system. In particular, in advantageous embodiments, the roll release signal comprises a dual release signal, the first directed at each suspension locking device and the second directed at the four bar linkage locking device. The same occurs with the block signal. For reasons of safety, the electrical control unit can generate a release signal upon reaching given conditions of the motor vehicle. For example, the roll-blocking system can be released when the number of motor revolutions exceeds a predetermined threshold, or if the speed of at least one of the two front wheels exceeds a predetermined safety speed, or if the driver operates the throttle valve via the handlebar accelerator.

The embodiment described above uses a mono-tube shock absorber with an external tank <NUM> and a valve between the external tank and the tube (inside the cylinder <NUM>) to control blocking of the springing movement. This solution is particularly advantageous, as the shock absorber thus obtained is very efficient. However, the concept on which the suspension locking device disclosed herein is based can also be implemented with two-tube or twin tube shock absorbers, which have the configuration schematically indicated in <FIG>. The same numbers in <FIG> indicate the same or functionally equivalent components to those described above with reference to <FIG>.

In the two-tube configuration, the tank <NUM> containing the compressible fluid <NUM> is in the form of an annular volume delimited by an outer sleeve <NUM> that surrounds the cylinder <NUM>. The annular volume between the outer sleeve <NUM> and the cylinder <NUM> is partially filled with oil (incompressible fluid) in the lower part thereof, indicated with <NUM> and partially with a gas (compressible fluid) in the upper part thereof, indicated with <NUM>. At the bottom, a duct <NUM> with a valve <NUM> places the chamber <NUM> in fluid communication with the tank defined between the sleeve <NUM> and the cylinder <NUM>. The fluid communication is provided in the lower area of the volume between cylinder <NUM> and sleeve <NUM> where oil collects by gravity, so that oil can pass through the duct <NUM> from and toward the chamber <NUM>. Also in this case, the springing movement of the suspension <NUM> is blocked closing the valve <NUM>, for example by means of an electromagnetic actuator <NUM>.

In some embodiments, the valve <NUM> can be adapted to completely close the duct <NUM>, entirely preventing the passage of oil from the first chamber <NUM> into the tank <NUM> and vice versa. In other embodiments, the valve may not completely close the duct that connects the first chamber <NUM> with the tank <NUM>, so that in the case of valve malfunctioning and failure to open during normal travel of the motor vehicle, springing movements, albeit minimal, can still be performed. In this way, the flow of oil from the first chamber <NUM> to the tank <NUM>, and vice versa, when the valve is closed is in any case substantially limited with respect to a condition with the valve open, so as to substantially obstruct springing movements, in particular when the motor vehicle is stationary.

As shown in the above described embodiments, the suspension locking device of each suspension is configured such that one of the two chambers (chamber <NUM>), into which the interior of the cylinder <NUM> of the shock absorber is divided by piston <NUM> sliding therein, is fluidly coupled to the tank <NUM>. Conversely, the second chamber <NUM> is fluidly coupled to the first chamber <NUM> through one or more passages, orifices or apertures 59A which extend through the piston. The second chamber <NUM> is not fluidly coupled to the tank <NUM> directly. Thus, locking of the suspension requires only one valve along the duct connecting the first chamber <NUM> to the tank <NUM>. The tank can be arranged in any suitable position around the cylinder <NUM>, which renders the suspension compact and reduces the cost thereof. The spring <NUM> can be arranged coaxial to the cylinder <NUM>, which again results in a simple and compact structure.

Claim 1:
A rolling motor vehicle (<NUM>) comprising:
a frame (<NUM>);
at least one rear driving wheel (<NUM>);
a left front steered wheel (<NUM>') and a right front steered wheel (<NUM>") placed side by side in a right-left direction (L-R);
a rolling four bar linkage (<NUM>) comprising: an upper cross member (<NUM>) extending transversely to a median plane of the motor vehicle (<NUM>), in a right-left direction; a lower cross member (<NUM>) extending transversely to the median plane of the motor vehicle (<NUM>), in a right-left direction; a left upright (<NUM>'), which connects the upper cross member (<NUM>) and the lower cross member (<NUM>) to each other; a right upright (<NUM>"), which connects the upper cross member (<NUM>) and the lower cross member (<NUM>) to each other;
a left support arm (<NUM>') constrained to the left upright (<NUM>') so as to rotate with respect thereto about a respective steering axis; wherein the left front steered wheel (<NUM>') is connected to the left support arm (<NUM>') with the interposition of a left suspension (<NUM>) comprising an elastic member (<NUM>) and a shock absorber (<NUM>);
a right support arm (<NUM>") constrained to the right upright (<NUM>") so as to rotate with respect thereto about a respective steering axis; wherein the right front steered wheel (<NUM>") is connected to the right support arm (<NUM>") with the interposition of a right suspension (<NUM>) comprising an elastic member (<NUM>) and a shock absorber (<NUM>);
characterized in that each shock absorber comprises a cylinder (<NUM>), inside which a piston (<NUM>) is slidingly housed, which divides the interior of the cylinder into a first chamber (<NUM>) and a second chamber (<NUM>), fluidly coupled to one another through at least one flow passage (59A) extending through the piston (<NUM>);
a suspension locking device comprising, for each of said suspensions (<NUM>), a valve (<NUM>) adapted to at least partially close a communication duct (<NUM>) which fluidly connects the first chamber (<NUM>) with a tank (<NUM>), preventing a flow of viscous fluid between the chamber (<NUM>) and the tank (<NUM>).