FR3120208A1 - SADDLE-TYPE VEHICLE, SUSPENSION KIT FOR A SADDLE-TYPE VEHICLE, AND METHOD OF UPDATING A SADDLE-TYPE VEHICLE - Google Patents

Abstract

The present invention relates to a saddle-type vehicle comprising a frame, a front wheel and a rear wheel, a suspension system (6) coupling the frame to the front and rear wheels in a variable relative position, and an engine; the vehicle comprising a sprung mass part, and an unsprung mass part comprising at least a part of the engine; the suspension system (6) being interposed between said mass parts, so as to support the suspended part with respect to the unsprung part. The suspension system (6) comprises a hydropneumatic mechanical hybrid suspension (15) comprising, in turn, an elastic element (7) having a first stiffness (k1), and a hydropneumatic spring (8) having a second stiffness (k2) , which are operatively coupled to each other and define an equivalent stiffness (keq) of the hybrid suspension (15) varying according to the relative position. Figure for abstract: Figure 2

Description

SADDLE-TYPE VEHICLE, SUSPENSION KIT FOR A SADDLE-TYPE VEHICLE, AND METHOD OF UPDATING A SADDLE-TYPE VEHICLE

TECHNICAL AREA
The present invention relates to a saddle-type vehicle comprising an improved suspension system, a suspension kit for a saddle-type vehicle and a method of updating a saddle-type vehicle.

TECHNOLOGICAL BACKGROUND
Saddle-type vehicles are known, comprising:
- a frame ;
- a front wheel, which can be steered relative to the frame and which can turn around its own first axis;
- a rear wheel, which is connected to the frame in a rotatable manner around its own second axis;
- a motor, which is adapted to supply a front and/or rear wheel with a traction torque.

Saddle-type vehicles are also known, comprising one rear wheel and two front wheels, or one front wheel and two rear wheels, or two front wheels and two rear wheels.

Additionally, saddle-type vehicles are also known having two front or rear wheels, which are mounted so as to be inclined with respect to the frame.

Saddle-type vehicles can be configured in different ways, for example as motorcycles, scooters or mopeds.

Saddle-type vehicles further include a suspension system, which couples the frame to the wheels in a variable relative position to one another.

The suspension system helps with vehicle handling and braking. Additionally, it provides safety and comfort by keeping the driver isolated from road noise, bumps and vibrations.

The suspension system includes, more specifically, a front suspension part and a rear suspension part, which respectively connect the front and rear wheels to the frame.

Generally, the front suspension part comprises one or two fork tubes and the rear suspension part comprises a swingarm with one or two suspensions.

Further, the mass of a saddle type vehicle can be divided into a sprung mass and an unsprung mass. In detail, the sprung mass includes the part of the mass of the vehicle that is supported by the suspension system. Additionally, the unsprung mass includes the part of the mass of the vehicle that is not supported by the suspension system.

The frame of saddle-type vehicles is for example part of the sprung mass and the rear and front wheels are part of the unsprung mass.

As a general rule, it is best to keep the unsprung mass of the vehicle as low as possible relative to the sprung mass of the vehicle. One reason for this is that the lower the unsprung mass, the less the suspension system has to do to keep the wheels - which are part of the unsprung mass - in contact with the ground.

A first category of saddle-type vehicles is known, in which the engine belongs to the suspended mass of the vehicle. For example, off-road motorcycles belong to this first category.

A second category of saddle-type vehicles is also known, in which the engine belongs at least in part to the unsprung mass of the vehicle. For example, most scooters and mopeds belong to this second category. In fact, the engine of scooters is generally mounted on the rear suspension part, and in particular on the swingarm.

In view of the above, for the same total mass of the vehicle, the suspension system of the saddle type vehicles of the second category is less efficient than the suspension system of the saddle type vehicles of the first category. In fact, for the same total mass of the vehicle, since the engine belongs to the unsprung mass, the unsprung mass of saddle-type vehicles of the second category is greater than the unsprung mass of saddle-type vehicles of the first category.

From a practical point of view, this means that the suspension system of saddle-type vehicles of the second category transmits the majority of vibrations and road irregularities to the driver.

Accordingly, there is a need in the industry to increase the efficiency of the suspension system of saddle-type vehicles in which the engine is included at least in part in the unsprung mass of the vehicle.

DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a vehicle of the saddle type, making it possible to satisfy at least one of the needs mentioned above in a simple and economical manner.

This object is achieved by a saddle-type vehicle comprising a frame, a front wheel, which can be steered with respect to said frame and can rotate around its own first axis, a rear wheel, which is connected to said frame in a manner rotatable around its own second axis, a suspension system coupling said frame with said front and rear wheels in a position relative to one another which varies along a direction perpendicular to the ground, and a motor adapted to provide to said front and/or rear wheel a traction torque. Said saddle-type vehicle has a total mass and includes a sprung mass portion having a first mass and an unsprung mass portion having a second mass. Said total mass is equal to the sum of said first mass and of said second mass. Said suspension system is interposed between said suspended mass part and said unsprung mass part, so as to support said suspended mass part with respect to said unsprung mass part. Said unsprung mass part rests, in use, on the ground. Said unsprung mass part comprises at least a part of said motor.

The saddle-type vehicle is characterized in that said suspension system comprises at least one hybrid mechanical hydropneumatic suspension, said hybrid suspension in turn comprising at least one elastic member having a first stiffness and at least one hydropneumatic spring having a second stiffness , said elastic element and said hydropneumatic spring being operatively coupled to each other and defining an equivalent stiffness of said hybrid suspension, said equivalent stiffness being variable as a function of said relative position.

In one embodiment, the suspension system may comprise a front suspension portion and a rear suspension portion, which couple said frame respectively to said front wheel and said rear wheel, and may further be characterized in that said rear suspension comprises said at least one hybrid suspension.

In one embodiment, said suspension system may include an adjustment system for adjusting said second stiffness of said hydropneumatic spring of said at least one hybrid suspension, so as to vary said equivalent stiffness of said at least one hybrid suspension.

In one embodiment, the rear wheel may define a median plane perpendicular to said second axis, said median plane in turn defining two opposite sides of said rear wheel, and the saddle type vehicle may further be characterized in that that said rear suspension part comprises two hybrid suspensions, which are arranged on respective opposite sides of said rear wheel.

In one embodiment, said adjustment system can be adapted to adjust the second stiffness of the respective hydropneumatic springs of the two hybrid suspensions included in said rear suspension part.

In one embodiment, said suspension system may further comprise at least one damper, which is suitable for damping the oscillations of said elastic element and/or of said hydropneumatic spring of said at least one hybrid suspension, said hydropneumatic spring of said at least a hybrid suspension comprising a first part, which is spaced from said shock absorber, and a second part, which is mounted coaxially on said shock absorber. Said first part may include, in turn:
- a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second stiffness, and
- a second chamber and a third chamber, which are in fluid communication with each other and contain an incompressible fluid.

Said first chamber and said second chamber may be formed within an interior volume of said first part, said third chamber being formed at said second part. Said first part may comprise, in turn, a partition wall, which seals off said first chamber from said second chamber, said partition wall being able to slide or deform inside said interior volume so as to cause a variation of said pressure. Said partition wall can be sliding or deformable depending on said interior volume and the volume of said incompressible fluid transferred between said second chamber and said third chamber.

In this embodiment, the saddle-type vehicle may further be characterized in that said adjustment system comprises an adjustment device which is in fluid communication with said second chamber and/or with said third chamber through the intermediate one or more ducts, said ducts and the volume of said second chamber and/or of said third chamber defining a volume, said adjustment device being adapted to vary said volume so as to cause the sliding of said wall of separation and variation of said second stiffness.

In one embodiment, said adjustment device may be in fluid communication with said respective second and/or third chambers of said two hybrid suspensions included in said rear suspension part, said adjustment device being adapted to vary said volume of so as to cause the sliding of the respective partition walls and the variation of the respective second stiffness of said two hybrid suspensions.

In one embodiment, said saddle-type vehicle may be a scooter or a moped.

The object of the invention is also achieved by a suspension kit 100 for a saddle vehicle. The suspension kit for a saddle-type vehicle comprises at least two hydropneumatic mechanical hybrid suspensions, each of said hybrid suspensions in turn comprising at least one elastic element having a first stiffness and at least one hydropneumatic spring having a second stiffness. Said elastic element and said hydropneumatic spring of each hybrid suspension are operatively coupled to each other and define a variable equivalent stiffness of the respective hybrid suspension.

The suspension kit for a saddle-type vehicle further comprises an adjustment system for adjusting said second stiffness of said respective hydropneumatic springs of said hybrid suspensions, so as to vary said equivalent stiffness of said respective hybrid suspensions. Hydropneumatic mechanical hybrid suspensions are adapted to be interposed between a suspended mass part and an unsprung mass part of said vehicle, which respectively have a first mass and a second mass. The sum of said first mass and of said second mass is equal to a total mass of said vehicle. Said unsprung mass part rests, in use, on the ground.

In one embodiment of the kit, each hydropneumatic spring may comprise a first part, which is adapted to be spaced from a respective shock absorber of said saddle-type vehicle, and a second part, which is adapted to be coaxially mounted on said shock absorber. , said first part comprising, in turn:
- a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second stiffness; and
- a second chamber and a third chamber, which are in fluid communication with each other and contain an incompressible fluid.

Said first chamber and said second chamber may be formed within an interior volume of said first part, said third chamber being formed at said second part. Said first part may comprise, in turn, a partition wall, which seals off said first chamber from said second chamber. Said partition wall can be slidable or deformable inside said interior volume so as to cause a variation in said pressure. Said partition wall can be sliding or deformable depending on said interior volume and the volume of said incompressible fluid transferred between said second chamber and said third chamber.

The kit can be characterized in that said adjustment system comprises an adjustment device which is in fluid communication with respective second and/or third chambers of said two hybrid suspensions by means of one or more ducts, said ducts and the volume of said second and/or said third chambers defining a volume, and said adjustment device being adapted to vary said volume so as to cause the sliding of respective partition walls and the variation of the respective second stiffness of said two hybrid suspensions.

The object of the invention is further achieved by a method of updating a saddle-type vehicle comprising, in turn:
- a frame ;
- a front wheel, which can be steered relative to the frame and which can rotate around its own first axis;
- a rear wheel, which is connected to the frame in a way that can rotate around its own second axis;
- A suspension system coupling said frame to said front and rear wheels in a position relative to one another that varies along a direction perpendicular to the ground; and
- a motor adapted to supply said front and/or rear wheel with a traction torque;

said method being characterized in that it comprises the steps of:
i) disposing at least one hydropneumatic mechanical hybrid suspension between a sprung mass part and an unsprung mass part of said vehicle, which respectively have a first mass and a second mass, the sum of said first mass and of said second mass being equal to a total mass of said vehicle, said unsprung mass portion resting, in use, on the ground, said at least one hybrid suspension comprising at least one elastic element having a first stiffness and at least one hydropneumatic spring having a second stiffness, said elastic element and said hydropneumatic spring of each hybrid suspension being operatively coupled to each other and defining an equivalent stiffness of said hybrid suspension, which is variable depending on said relative position, and
ii) fluidically connecting said at least one hydropneumatic mechanical hybrid suspension to an adjustment system for adjusting said second stiffness, so as to vary said equivalent stiffness.

BRIEF DESCRIPTION OF DRAWINGS
A preferred non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
- the is a side view of a saddle-type vehicle according to the present invention;
- the is a diagram of part of a saddle-type vehicle suspension system of the , with parts being removed for clarity;
- the illustrates respective steps of a method for updating the saddle-type vehicle of the ;
- the illustrates respective steps of a method for updating the saddle-type vehicle of the ;
- the illustrates respective steps of a method for updating the saddle-type vehicle of the ; and
- the is a graph illustrating the characteristic curves of a suspension of the suspension system of the under different respective adjustment conditions.

BEST MODE FOR CARRYING OUT THE INVENTION
By referring to the , reference numeral 1 indicates a saddle type vehicle.

In the embodiment shown, the saddle type vehicle is a scooter. Alternatively, the saddle-type vehicle is a moped.

In the rest of the present description, expressions such as "front", "rear", and the like are used with reference to a normal direction of progression and to a normal operational position of the vehicle 1 shown in the appended figures.

As shown on the , the vehicle 1 comprises substantially:
- a frame 2;
- a front wheel 3, which can be steered with respect to the frame 2 and which can rotate around its own axis A;
- a rear wheel 4, which is connected to the frame 2 in a rotatable manner around its own axis B;
- A motor 5 adapted to supply the front and/or rear wheels 3, 4 with a traction torque; and
- a suspension system 6 coupling the frame 2 to the front and rear wheels 3, 4 in a relative position of one with respect to the others that varies along a direction Z perpendicular to the ground G.

In the remainder of this description, the word "ground" is used to indicate the surface on which the front and rear wheels 3, 4 rest.

In particular, vehicle 1 has a total mass M. This means that the sum of the mass of all the components forming vehicle 1 is equal to the total mass M.

Furthermore, the vehicle 1 comprises a sprung mass part S having a mass s and an unsprung mass part U having a mass u. In detail, the suspended mass part S comprises all the components of the vehicle 1 which are supported by the suspension system 6; on the contrary, the part of unsprung mass U includes all the components of the vehicle 1 which are not supported by the suspension system 6. The sum of the mass s and the mass u is equal to the total mass M.

In other words, the suspension system 6 is interposed between the suspended mass part S and the unsprung mass part U to support the suspended mass part S with respect to the unsprung mass part U. In addition, the unsprung mass part U is adapted to rest, in use, on the ground G.

Moreover, certain components of the vehicle 1 can belong partly to the sprung mass part S and partly to the unsprung mass part U.

In detail, the motor 5 belongs at least in part to the unsprung mass part U. In other words, the mass of the motor 5 contributes to the mass u of the unsprung mass part U. Therefore, at least part of the mass of the engine 5 is not supported by the suspension system 6.

Further, the suspension system 6 comprises a front suspension part 6a and a rear suspension part 6b, which respectively couple the front and rear wheels 3, 4 to the frame 2.

The front and rear suspension parts 6a, 6b are loaded by respective loads which depend on the mass s, the mass of the driver and any passengers and the mass of any goods transported on the vehicle 1. The loads acting on the front and rear suspension parts 6a, 6b also depend on the loads exerted respectively on the front and rear wheels 3, 4 by the ground G.

Generally, when the vehicle 1 is stationary or in a state of average progression, the load acting on the rear suspension part 6b is greater than the load acting on the front suspension part 6a.

In detail, the vehicle 1 is stationary when its speed relative to the ground G is equal to zero. Furthermore, the vehicle 1 is in the state of average progression when it is advancing on a sufficiently regular and not steep road, for example a road in an urban area, at a speed compatible with the speed limits of the urban area. . For example, the vehicle 1 is not in the average progress state when it is moving on a bumpy surface and/or an uphill road.

For example, when the vehicle 1 is unloaded, i.e. without a driver or passenger riding it and without any other load being carried by it, the ratio between the load acting on the front suspension part 6a and the load acting on the rear suspension part 6b is equal to 1:4. Moreover, when the vehicle 1 is loaded, for example by the weight of the driver, the ratio between the load acting on the front suspension part 6a and the load acting on the rear suspension part 6b can be even less than 1:4 .

In the embodiment shown in the , a motor 5 is mounted on the rear suspension part 6b.

The rear suspension part 6b comprises, in detail, a swing arm 50, which is adapted to attach the rear wheel 4 to the frame 2. In more detail, the motor 5 is attached to the swing arm 50.

In the embodiment shown, the oscillating arm 50 is a double-sided oscillating arm, that is to say it comprises two arms surrounding the respective sides of the rear wheel 4 with respect to a median plane P defined by the rear wheel 4 and perpendicular to axis B.

Advantageously, the suspension system 6 comprises at least one hydropneumatic mechanical hybrid suspension 15.

Such a hybrid suspension 15 is known for example from WO-A1-2015155712 and IT-A1-102012902090112 and is marketed by the company Umbria Kinetics under the name AirTender®.

In the embodiment shown, the suspension system 6 comprises two hybrid suspensions 15 at the rear suspension part 6b.

In detail, the two hybrid suspensions 15 are arranged on either side of the rear wheel 4 with respect to the plane P. In more detail, the two hybrid suspensions 15 are constrained at least indirectly between the oscillating arm 50 and the frame 2. This means that the hybrid suspensions 15 could be constrained with respect to the swing arm 50 by means of an intermediate component, such as a lever.

The following description will be made with reference to a single hybrid suspension 15 mounted on the rear wheel 4, all the hybrid suspensions 15 being identical to each other.

The hybrid suspension 15 comprises, in detail, an elastic element 7 having a stiffness k1 and a hydropneumatic spring 8 having a stiffness k2 ( ). In detail, the stiffness k2 is less than the stiffness k1.

Preferably, the rear suspension part 6b comprises two shock absorbers 11, which are respectively arranged on both sides of the rear wheel 4 with respect to the plane P.

In detail, the hybrid suspension 15 is adapted to interact with one of the two shock absorbers 11 of the suspension system 6, which is constrained between the rear wheel 4 and the frame 2 and defines an axis C. The shock absorber 11 is adapted to dampen the oscillations of the elastic element 7 and/or of the hydropneumatic spring 8.

In the embodiment shown, damper 11 is a viscous damper. In known manner, the damper 11 comprises a cylinder containing a viscous fluid (for example oil) and a slider, which is adapted to slide in the cylinder. In detail, the cylinder and the slider are respectively integral with the frame 2 and the rear wheel 4, or vice versa, and the slider is adapted to slide in the cylinder according to the relative position between the frame 2 and the rear wheel 4 .

The elastic element 7 and the hydropneumatic spring 8 are operatively coupled to each other in series and define an equivalent stiffness keq of the hybrid suspension 15.

It is also possible to define an equivalent deformation xeq of the hybrid suspension 15. This equivalent deformation xeq is inversely proportional to the equivalent stiffness keq and directly proportional to the loads applied to the hybrid suspension 15.

The equivalent stiffness keq is variable depending on the relative position between the frame 2 and the wheels 3, 4. In detail, the equivalent stiffness keq can be different for different values of the equivalent deformation xeq.

The elastic element 7 is a mechanical spring, which is adapted to store and subsequently release elastic energy through the elastic deformation of at least part of it. Furthermore, the elastic element 7 is adapted to store and release elastic energy without compression or expansion of any fluid. In the embodiment shown, the elastic element 7 is a coil spring and is arranged coaxially with respect to the damper 11 ( ).

In detail, the elastic element 7 is adapted to cooperate with the damper 11. In more detail, the elastic element 7 is able to compress or to expand along the axis C depending on the sliding of the damper slider 11 inside the respective cylinder.

Furthermore, as illustrated in Figures 2 and 5, each hydropneumatic spring 8 comprises a first part 16 and a second part 17. Preferably, the first part 16 is spaced from the damper 11 and the second part 17 is mounted coaxially on the shock absorber 11 ( ).

In addition, the hydropneumatic spring 8 includes:
- a first chamber 20, which contains a gas at a pressure p;
- a second chamber 22 and a third chamber 23, which are in fluid communication with each other and contain an incompressible fluid.

In the embodiment shown, the gas contained in the first chamber 20 is nitrogen and the incompressible fluid contained in the second and third chambers 22, 23 is oil.

As illustrated in Figures 2 and 5, the first and second chambers 20, 22 are formed inside an interior volume V of the first part 16 and the third chamber 23 is formed inside the second part 17 .

The first part 16 comprises, in turn, a partition wall 21, which separates the first chamber 20 from the second chamber 22 in a leaktight manner and which is sliding or deformable inside the interior volume V along a direction D. Preferably, but not necessarily, direction D is parallel to axis C (Figures 2 and 5).

As illustrated in Figures 2 and 5, the partition wall 21 is a piston having a cross section Ω perpendicular to the direction D. Alternatively, the partition wall 21 can be a deformable membrane.

In detail, since the sum of the volume of the first chamber 20 and the volume of the second chamber 22 is equal to the interior volume V, the sliding of the partition wall 21 along the direction D causes a reduction in the volume of the first chamber 20 and an increase in the volume of the second chamber 22, or vice versa. In addition, a decrease (increase) in the volume of the first chamber 20 causes an increase (decrease) in the pressure p of the gas contained therein.

In general, the separation wall 21 is sliding according to the pressure p of the gas contained inside the first chamber 20 and according to the volume of incompressible fluid transferred between the second chamber 22 and the third chamber 23 .

In particular, the separation wall 21 can be slid so as to cause the compression of the gas only if the incompressible fluid contained in the second chamber 22 exerts on the separation wall 21 a force FΩ greater than a threshold force F0 exerted by the gas on the partition wall 21. This threshold force F0 depends in detail on a threshold value p0 of the pressure p and the extension of the cross section Ω of the partition wall 21.

Furthermore, it is possible to demonstrate experimentally that the rigidity k2 of the hydropneumatic spring 8 is directly proportional to the pressure p and, in particular, to the threshold value p0.

The pressure threshold p0 is also variable depending on the volume of the first chamber 20. In detail, the pressure threshold p0 is increased if the gas contained in the first chamber 20 is compressed, and decreased if the gas contained in the first chamber 20 is dilated.

As shown in Figures 2 and 5, the second part 17 of the hybrid suspension 15 comprises:
- A first element 24, which is mounted in one piece and coaxially with respect to the damper 11; and
- a second element 25, which is adapted to cooperate with the elastic element 7 and is mounted coaxially with respect to the damper 11 in a movable manner with respect to the first element 24.

The second element 25 is arranged radially outward with respect to the first element 24. In detail, the second element 25 has a radially inner surface 26, which faces the first element 24 (FIGS. 2 and 5).

In particular, the first element 24 and the radially inner surface 26 define the third chamber 23. The volume of the third chamber 23 is variable depending on the relative position of the second element 25 with respect to the first element 24 along the axis vs.

As the third chamber 23 contains an incompressible fluid, any relative movement between the first element 24 and the second element 25 causes the transfer of the incompressible fluid between the second chamber 22 and the third chamber 23. Similarly, any variation in the interior volume V of the first part 16 can cause a transfer of incompressible fluid from the second chamber 22 to the third chamber 23 or vice versa and, consequently, a variation of the relative position of the second element 25 with respect to the first element 24.

A plurality of characteristic curves of the hybrid suspension 15 is illustrated on the . In detail, the is a graph of the force applied to the hybrid suspension 15 as a function of its equivalent deformation xeq. Furthermore, the equivalent stiffness keq corresponds to the slope of the characteristic curves shown on the . Therefore, a point of the characteristic curves defines a particular operating condition of the hybrid suspension 15.

In addition, each of the characteristic curves represented on the corresponds to a specific value of the threshold pressure p0.

The characteristic curve shown as a continuous line on the comprises a section I, a section II and a section III and will be referred to below as the “first characteristic curve”.

In the embodiment shown, the first characteristic curve corresponds to an adjustment condition of the hybrid suspension 15 determined by the factory settings of the hybrid suspension 15.

Section I extends between the origin O of the reference system and a point L, which is defined by a value xeqL of equivalent deformation xeq; section II extends between point L and a point J, which is defined by a value xeqJ of equivalent deformation xeq; section III extends between point J and a point K, which is defined by a value xeqK of the equivalent deformation xeq.

When the operating point of the hybrid suspension 15 belongs to the first characteristic curve and the equivalent deformation xeq is between zero and the value xeqL, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1; when the equivalent deformation xeq is between the value xeqL and the value xeqJ, the hydropneumatic spring 8 operates and the equivalent stiffness keq is substantially equal to the stiffness k2; when the equivalent deformation xeq is between the value xeqJ and the value xeqK, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1.

In addition, the slope of section I is higher than the slope of section II. This is due to the fact that the stiffness k2 is lower than the stiffness k1.

The illustrates two additional characteristic curves, which correspond to two respective different values of the threshold pressure p0 and, consequently, to two additional adjustment configurations of the hybrid suspension 15, as will be described in more detail below.

Indeed, the suspension system 6 further comprises an adjustment system 9 adapted to allow the variation of the rigidity k2 of the hydropneumatic spring 8, with the aim of varying the equivalent rigidity keq.

In detail, the adjustment system 9 is adapted to allow the variation of the stiffness k2 of the hydropneumatic springs 8 of one or more hybrid suspensions 15 of the suspension system 6.

In particular, the two or more suspensions 15 and the adjustment system 9 define a suspension kit 100 for the vehicle 1.

In the embodiment shown, the adjustment system 9 controls the stiffness k2 of the two hybrid suspensions 15 of the rear suspension part 6b ( ).

The adjustment system 9 is adapted to adjust the stiffness k2 of one or more hybrid suspensions 15 by causing a variation in the volume of the respective first chambers 20. In fact, as described above, a variation in the volume of the first chamber 20 corresponds to a variation in the threshold pressure p0, which is directly proportional to the stiffness k2.

In particular, as illustrated in FIGS. 2 and 5, the adjustment system 9 comprises an adjustment device 30, which is in fluid communication with the second and/or third chambers 22, 23 of the two hybrid suspensions 15 of the part rear suspension 6b by means of one or more conduits 31.

Ducts 31 define an interior volume containing the same incompressible fluid as the second and third chambers 22, 23 of the two hybrid suspensions 15.

In the embodiment shown, the conduits 31 include:
- A conduit 32, which fluidically connects the two suspensions 15 to each other; and
- a conduit 33, comprising a first end 33a and a second end 33b, which are opposite to each other.

The conduit 33 is fluidly connected to the conduit 32 at the level of the first end 33a, and the adjustment device 30 is arranged at the level of the second end 33b.

Preferably, the adjustment device 30 is spaced from the two suspensions 15.

In particular, the sum of the volume of the second and third chambers 22, 23 of the respective suspensions 15 and of the interior volume of the ducts 31 defines a total volume W.

The adjustment device 30 is adapted to adjust the stiffness k2 of the two suspensions 15 by varying the total volume W.

In detail, the adjustment device 30 can be slid inside the duct 33 between a retracted position, in which the volume W is equal to a first value W1, and an extended position, in which the volume W is equal at a second value W2 lower than the first value W1. The adjustment device 30 can further slide to any of the continuous positions between the retracted position and the extended position. In particular, the adjustment device 30 can be slid manually or automatically.

As mentioned above, since the fluid contained inside the second and third chambers 22, 23 and the ducts 31 is incompressible, any variation in the volume W can cause the respective separation walls 21 of the hybrid suspensions 15 to slide at the inside the respective interior volumes V.

In particular, if the force FΩ is greater than the threshold force F0, each partition 21 is adapted to slide along the direction D, in order to reduce the volume of the first chamber 20 respectively. Consequently, the pressure p of the gas contained in each first chamber 20 is increased. Alternatively or additionally, at least a portion of the incompressible fluid is transferred between each second chamber 22 and the respective third chamber 23.

On the contrary, if the volume W is increased, each dividing wall 21 is adapted to slide along the direction D, in order to increase the volume of the first chamber 20 respectively. Consequently, the pressure p of the gas contained in each first chamber 20 is increased. Alternatively or additionally, at least a portion of the incompressible fluid is transferred between each second chamber 22 and the respective third chamber 23.

In particular, the pressure threshold p0 is equal to a value p01 when the volume W is equal to the value W1, and to a value p02 when the volume W is equal to the value W2. Furthermore, since the rigidity k2 of the hydropneumatic spring 8 is directly proportional to the threshold value p0, the rigidity k2, when the pressure threshold p0 is equal to the value p01, is less than the rigidity k2 when the pressure threshold p0 is equal to the value p02.

As mentioned above, the further illustrates a dashed line with a dot and a dotted line.

In particular, the line in broken lines by a point corresponds to a condition of adjustment of the hybrid suspension 15 in which the pressure threshold p0 is greater than the pressure threshold p0 corresponding to the first characteristic curve and to the pressure threshold p0 corresponding to the dotted line. By way of example, the pressure threshold p0 corresponding to the line broken by a dot is equal to the value p02, and the pressure threshold p0 corresponding to the dotted line is equal to the value p01.

In detail, the dotted line is arranged above section II and includes section I' and section II'.

In more detail, the section I' extends between the point L and a point R, which is defined by a value xeqR of equivalent deformation xeq which is greater than the value xeqL; section II' extends between point R and a point Q, which is defined by a value xeqQ of the equivalent deformation xeqQ.

Section I' has the same slope as section I and joins section I at point L. In other words, section I' is the extension of section I.

Section II' joins section III at point Q and has a higher slope than section II.

It is therefore possible to define a second characteristic curve of the hybrid suspension 15, which is composed successively: of section I, of section I', of section II' and of section III between point Q and point K.

In particular, when the operating point of the hybrid suspension 15 belongs to the second characteristic curve and the equivalent deformation xeq is between zero and the value xeqR, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1; when the equivalent deformation xeq is between the value xeqR and the value xeqQ, the hydropneumatic spring 8 operates and the equivalent stiffness keq is substantially equal to the stiffness k2; when the equivalent deformation xeq is between the value xeqQ and the value xeqK, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1. In detail, as described above, the stiffness k2, when the operating point of the hybrid suspension 15 belongs to the second characteristic curve (section II'), is greater than the stiffness k2 when the operating point of the suspension hybrid 15 belongs to the first characteristic curve (section II).

In addition, the dotted line is arranged below the section II and includes a section II'' and a section III'' ( ).

In detail, section II'' extends between a point N and a point T, which are respectively defined by values xeqN and xeqT of the equivalent deformation xeq; section III’’ extends between point T and point J. In detail, the xeqN value is lower than the xeqL value.

Section II'' has a lower slope than section II and joins section I at point N. Section III'' joins section III at point J, and has the same slope as section III. In other words, section III’’ is the extension of section III.

It is therefore possible to define a third characteristic curve of the hybrid suspension 15, which consists successively: of section I between point O and point N, of section II'', of section III'' and of section III.

In particular, when the operating point of the hybrid suspension 15 belongs to the third characteristic curve and the equivalent deformation xeq is between zero and the value xeqN, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1; when the equivalent deformation xeq is between the value xeqN and the value xeqT, the hydropneumatic spring 8 operates and the equivalent stiffness keq is substantially equal to the stiffness k2; when the equivalent deformation xeq is between the value xeqT and the value xeqK, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1. In detail, as described above, the stiffness k2, when the operating point of the hybrid suspension 15 belongs to the third characteristic curve (section II'), is greater than the stiffness k2 when the operating point of the suspension hybrid 15 belongs to the first characteristic curve (section II).

In particular, when the vehicle 1 is in the average progression state, the load acting on the hybrid suspension 15 is equal to a value Av ( ).

The value Av corresponds to three possible operating points of the hybrid suspension 15 which respectively belong to the first, second and third characteristic curves, according to the value of the pressure threshold p0. These three points belong respectively to section II of the first characteristic curve, to section I' of the second characteristic curve and to section II'' of the third characteristic curve.

The operation of the saddle type vehicle 1 is described from a state in which the hybrid suspensions 15 of the rear suspension part 6b are set to their respective factory settings and, therefore, their respective operating points belong to the first characteristic curve. In particular, the vehicle 1 is in the state of average progression and, therefore, the respective operating points of the hybrid suspensions 15 belong to section II ( ).

As a result, the equivalent stiffness keq is substantially equal to the stiffness k2 as in section II. As a result, the suspension system 6 reacts less rigidly to the loads acting on the hybrid suspensions 15 than when the equivalent rigidity keq is substantially equal to the rigidity k1.

If the vehicle 1 is supposed to be subjected to a much higher load than the value Av (for example due to the presence of a passenger), the adjustment device 30 can advantageously be slid in the conduit 33 towards the extended position. , in which the volume W is equal to the second value W2.

Consequently, the volume of the first chambers 20 of the two hybrid suspensions 15 is compressed and the threshold pressure p0 becomes equal to the value p02. Consequently, the stiffness keq is substantially equal to the stiffness k2 (comparison of section II' on the ) also when the hybrid suspensions 15 are loaded with a load which is substantially greater than the load Av.

If, on the contrary, the vehicle 1 is supposed to be subjected to a load lower than the value Av, the adjustment device 30 can advantageously be slid inside the duct 33 towards the retracted position, in which the volume W is equal to the first value W1.

Consequently, the volume of the first chambers 20 of the hybrid suspensions 15 is compressed and the threshold pressure p0 becomes equal to the value p01. Consequently, the stiffness keq is substantially equal to the stiffness k2 (comparison of section II' on the ) also when the hybrid suspensions 15 are loaded with a load which is substantially less than the load Av.

The described solution can also be easily adapted (with a so-called "retrofitting" or "updating" operation) to existing saddle-type vehicles in which the engine 5 belongs at least partly to the unsprung mass part U, by: removing the existing spring coils, if necessary, arranged coaxially with respect to the dampers 11 (FIGS. 3 and 4); arranging one or more suspensions 15 between the suspended mass part S and the unsprung mass part U of the existing vehicle; and fluidically connecting the one or more hybrid suspensions 15 to the adjustment system 9 for the purpose of adjusting the second stiffness k2 of one or more respective hybrid suspensions 15, so as to vary the equivalent stiffness keq ( ).

The advantages of vehicle 1 and kit 100 will become clear from the above description.

In particular, the suspension system 6 comprises at least one hybrid suspension 15 having an equivalent rigidity keq, which is variable as a function of the relative position between the frame 2 and the wheels 3, 4. Thus, the vehicle 1, which belongs to the second category of saddle-type vehicles described in the introductory part of this description comprises a suspension system 6 that is markedly more efficient than the suspension system of known vehicles belonging to the second category.

Indeed, as the equivalent rigidity keq is variable according to the relative position between the frame 2 and the wheels 3, 4, the suspension system 6 can be adjusted so as to reduce the vibrations and road irregularities transmitted to the driver.

Such an improvement in the efficiency of the suspension system 6 counterbalances the fact that the mass u of the unsprung mass part U with respect to the mass s of the sprung mass part S is greater for the vehicle 1 than for the vehicles of the first category, because the engine 5 belongs at least in part to the unsprung mass part U.

Further, since the suspension system 6 includes an adjustment system 9 for adjusting the stiffness k2, the dynamic behavior of the vehicle 1 can be adjusted according to the driver's needs or the road characteristics. In particular, the dynamic behavior of the vehicle 1 can be adjusted according to the presence of a passenger or additional loads on the vehicle.

Indeed, if the vehicle 1 is supposed to be used under the conditions of average progression, it is advantageous to adjust the hybrid suspensions 15 to their respective factory settings (in this way, the equivalent rigidity keq is substantially equal to the rigidity k2 when the hybrid suspensions 15 are charged by the charge Av).

On the other hand, if the vehicle 1 is supposed to be loaded with a much higher load than the value Av, it is advantageous to cause the adjustment device 30 to slide so as to adjust the threshold pressure p0 equal to the pressure value p02 . Therefore, the stiffness keq is substantially equal to the stiffness k2 also when the hybrid suspensions 15 are loaded by respective loads much higher than the load Av. In this way, vibrations and road irregularities transmitted to the driver can be advantageously reduced even when the vehicle 1 is subjected to severe loading conditions.

In addition, since the rear suspension part 6b comprises two hybrid suspensions 15, the efficiency of the suspension system 6 is further improved. Indeed, as described above, the load acting on the rear suspension part 6b is generally greater than the load acting on the front suspension part 6a.

In addition, since the suspension system 6 includes a single adjustment system 9 for the two hybrid suspensions 15 of the rear suspension part 6b, the equivalent stiffness keq can be adjusted without affecting the layout of the vehicle 1.

Finally, it appears that modifications and variants not departing from the scope of protection of the claims can be made concerning the vehicle 1 and the kit 100 according to the present invention.

In particular, the swing arm 50 can be a unilateral swing arm, comprising a single arm arranged on one side of the rear wheel 4 with respect to the median plane P. Consequently, the suspension system 6 would comprise only a single suspension hybrid 15 arranged on the same side of the rear wheel 4 as that where the single arm of the swing arm 50 is arranged.

On the other hand, the suspension system 6 can comprise hybrid suspensions 15 both at the level of the rear and front suspension parts 6a, 6b. In detail, the suspension system 6 may comprise two or more hybrid suspensions 15 at the front suspension part 6a.

Therefore, the suspension system 6 may comprise an adjustment system 9 adapted to control the rigidity k2 of the hybrid suspensions 15 belonging to the front suspension part 6a and an adjustment system 9 adapted to control the rigidity k2 of the hybrid suspensions 15 belonging to the rear suspension part 6b. As a variant, the suspension system 6 may comprise only one adjustment system 9 adapted to control the rigidity k2 of the hybrid suspensions 15 belonging to both the front and rear suspension parts 6a, 6b.

Claims (9)

Saddle-type vehicle (1) comprising:

- a frame (2);

- a front wheel (3), which can be steered relative to said frame (2) and can rotate around its own first axis (A);

- a rear wheel (4), which is connected to said frame (2) so as to be able to rotate around its own second axis (B);

- a suspension system (6) coupling said frame (2) to said front and rear wheels (3, 4) in a position relative to one with respect to the others which is variable along a direction (Z) perpendicular to the ground ( G); and

- a motor (5) adapted to supply said front and/or rear wheel (3, 4) with a traction torque;

- said saddle type vehicle (1) having a total mass (M) and comprising a sprung mass part (S) having a first mass (s) and an unsprung mass part (U) having a second mass (U ); said total mass (M) being equal to the sum of said first mass (s) and of said second mass (u); said suspension system (6) being interposed between said suspended mass part (S) and said unsprung mass part (U), so as to support said suspended mass part (S) with respect to said unsprung mass part (U); said unsprung mass portion (U) resting, in use, on the ground (G);

- said unsprung mass part (U) comprising at least part of said motor (5);

- characterized in that said suspension system (6) comprises at least two hydropneumatic mechanical hybrid suspensions (15);

- each of said hybrid suspensions (15) comprising, in turn, at least one elastic element (7) having a first stiffness (k1) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) being operatively coupled to each other and defining an equivalent stiffness (keq) of said respective hybrid suspension (15); said equivalent stiffness (keq) being variable as a function of said relative position; and

- an adjustment system (9) for adjusting said second stiffness (k2) of said respective hydropneumatic springs (8) of said hybrid suspensions (15), so as to vary said equivalent stiffness (keq) of said respective hybrid suspensions (15). A saddle type vehicle according to claim 1, wherein said suspension system (6) comprises a front suspension part (6a) and a rear suspension part (6b), which couple said frame (2) respectively to said front wheel (3) and said rear wheel (4);

characterized in that said rear suspension part (6b) comprises said at least two hybrid suspensions (15). Saddle-type vehicle according to claim 2, wherein said rear wheel (4) defines a median plane (P) perpendicular to said second axis (B);

said median plane (P) defining, in turn, two opposite sides of said rear wheel (4);

characterized in that the at least two hybrid suspensions (15) are arranged on respective opposite sides of said rear wheel (4). A saddle-type vehicle according to claim 3, wherein said suspension system (6) further comprises at least one damper (11), which is adapted to dampen oscillations of said elastic member (7) and/or said hydropneumatic spring ( 8) one of said at least two hybrid suspensions (15);

said hydropneumatic spring (8) of said hybrid suspension (15) comprising a first part (16), which is spaced from said shock absorber (11) and a second part (17), which is mounted coaxially on said shock absorber (11);

said first part (16) comprising, in turn:

-a first chamber (20), which contains a gas at a pressure (p); said pressure (p) being directly proportional to said second stiffness (k2);

- a second chamber (22) and a third chamber (23), which are fluidically connected to each other and contain an incompressible fluid;

said first chamber (20) and said second chamber (22) being formed inside an interior volume (V) of said first part (16); said third chamber (23) being formed at said second portion (17);

said first part (16) comprising, in turn, a partition wall (21), which sealably separates said first chamber (20) from said second chamber (22); said separation wall (21) being able to slide or deform inside said interior volume (V) so as to cause a variation of said pressure (p);

said partition wall (21) being sliding or deformable depending on said internal volume (V) and the volume of said incompressible fluid transferred between said second chamber (22) and said third chamber (23);

characterized in that said adjustment system (9) comprises an adjustment device (30) which is in fluid communication with said second chamber (22) and/or with said third chamber (23) by means of one or more ducts (31);

said ducts (31) and the volume of said second chamber (22) and/or of said third chamber (23) defining a volume (W);

said adjustment device (30) being adapted to vary said volume (W) in such a way as to cause said separation wall (21) to slide and said second stiffness (k2) to vary. Saddle-type vehicle according to claim 4, characterized in that said adjustment device (30) is in fluid communication with said respective second chambers (22) and/or third chambers (23) of said two hybrid suspensions (15) included in said rear suspension part (6b);

said adjustment device (30) being adapted to vary said volume (W) so as to cause the sliding of the respective partition walls (21) and the variation of the respective second rigidities (k2) of the said two hybrid suspensions (15). Saddle-type vehicle according to any one of the preceding claims, characterized in that said saddle-type vehicle is a scooter or a moped. Suspension kit (100) for a saddle-type vehicle (1) comprising:

- at least two hydropneumatic mechanical hybrid suspensions (15); each of said hybrid suspensions (15) comprising, in turn, at least one elastic element (7) having a first stiffness (k1) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) of each hybrid suspension (15) being operatively coupled to each other and defining a variable equivalent stiffness (keq) of the respective hybrid suspension (15); and

- an adjustment system (9) for adjusting said second stiffness (k2) of said respective hydropneumatic springs (8) of said hybrid suspensions (15), so as to vary said equivalent stiffness (keq) of said respective hybrid suspensions (15);

said hydropneumatic mechanical hybrid suspensions (15) being adapted to be interposed between a sprung mass part (S) and an unsprung mass part (U) of said vehicle (1), which respectively have a first mass (s) and a second mass (u); the sum of said first mass (s) and of said second mass (u) being equal to a total mass (M) of said vehicle (1); said unsprung mass portion (U) resting, in use, on the ground (G). A kit according to claim 7, wherein each hydropneumatic spring (8) comprises a first part (16), which is adapted to be spaced from a respective shock absorber (11) of said saddle-type vehicle (1) and a second part ( 17), which is adapted to be coaxially mounted on said damper (11);

said first part (16) comprising, in turn:

- a first chamber (20), which contains a gas at a pressure (p); said pressure (p) being directly proportional to said second stiffness (k2);

- a second chamber (22) and a third chamber (23), which are fluidically connected to each other and contain an incompressible fluid;

said first chamber (20) and said second chamber (22) being formed inside an interior volume (V) of said first part (16); said third chamber (23) being formed at said second portion (17);

said first part (16) comprising, in turn, a partition wall (21), which sealably separates said first chamber (20) from said second chamber (22); said separation wall (21) being able to slide or deform inside said interior volume (V) so as to cause a variation of said pressure (p);

said partition wall (21) being sliding or deformable depending on said internal volume (V) and the volume of said incompressible fluid transferred between said second chamber (22) and said third chamber (23);

characterized in that said adjustment system (9) comprises an adjustment device (30) which is in fluid communication with said second chambers (22) and/or with said respective third chambers (23) by means of one or several conduits (31);

said ducts (31) and the volume of said second chambers (22) and/or of said third chambers (23) defining a volume (W);

said adjustment device (30) being adapted to vary said volume (W) so as to cause the sliding of said separation wall (21) and the variation of said respective second rigidity (k2) of said two hybrid suspensions (15) . A method of updating a saddle-type vehicle (1); said saddle-type vehicle (1) comprising, in turn:

- a frame (2);

- a front wheel (3), which can be steered relative to said frame (2) and can rotate around its own first axis (A);

- a rear wheel (4), which is connected to said frame (2) so as to be able to rotate around its own second axis (B);

- a suspension system (6) coupling said frame (2) to said front and rear wheels (3, 4) in a position relative to one with respect to the others which is variable along a direction (Z) perpendicular to the ground ( G); and

- a motor (5) adapted to supply said front and/or rear wheel (3, 4) with a traction torque;

said method being characterized in that it comprises the steps of:

i) arranging at least two hydropneumatic mechanical hybrid suspensions (15) between a sprung mass part (S) and an unsprung mass part (U) of said vehicle (1), which respectively have a first mass (s) and a second mass (u); the sum of said first mass (s) and of said second mass (u) being equal to a total mass (M) of said vehicle (1); said unsprung mass portion (U) resting, in use, on the ground (G);

each of said at least two hybrid suspensions (15) comprising at least one elastic element (7) having a first stiffness (k1) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) of each hybrid suspension (15) being operatively coupled to each other and defining an equivalent stiffness (keq) of said hybrid suspension (15), which is variable as a function of said relative position; and

ii) fluidically connecting said at least one hydropneumatic mechanical hybrid suspension (15) to an adjustment system (9) to adjust said second stiffness (k2), so as to vary said equivalent stiffness (keq).