FR3120017A1 - ADJUSTABLE HEIGHT SADDLE-TYPE VEHICLE AND METHOD OF OPERATING THEREOF - Google Patents

Abstract

The present invention relates to a saddle type vehicle (1) comprising a frame (2); a front wheel (3) and a rear wheel (4), which are adapted to move the frame (2) relative to the ground (G) along a direction of progression (X); a saddle (5), which is mounted on the frame (2) at a height (h) measured along a second direction (Z) perpendicular to the ground (G); and a suspension system (6) coupling the frame (2) with the wheels (3, 4) at a variable relative position with respect to each other. The suspension system (6) comprises a hybrid mechanical-hydropneumatic suspension comprising an elastic element having a first stiffness and a hydropneumatic spring having a second stiffness. The vehicle (1) comprises an adjustment system configured to automatically adjust the second stiffness according to the parameters (π) of the vehicle (1), so as to modify the height (h). Figure for abstract: Figure 1

Description

ADJUSTABLE HEIGHT SADDLE-TYPE VEHICLE AND METHOD OF OPERATING THEREOF

The present invention relates to a saddle-height type vehicle and a control method thereof.

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 suspension system coupling the frame with the wheels in a variable relative position with respect to each other.

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.

In addition, saddle-type vehicles can be configured in different ways, for example as motorcycles, as scooters or as mopeds and are also known having two front or rear wheels, which are mounted in such a way as to be tilted by relation to the frame.

Saddle-type vehicles further comprise a saddle for the driver and any passenger, which is arranged at a certain height from the ground. In detail, this height - also known as "access to the ground" - is variable depending on the relative position between the frame and the wheels.

In general, the height of the seat when the vehicle is stationary is defined at the design stage as part of a compromise between various functional and aesthetic requirements.

First of all, when the vehicle is stationary, the saddle must be arranged so as to be easily accessible to the driver. In addition, when the vehicle is stationary or substantially stationary, the driver must be able to place both feet on the ground while straddling the saddle. Consequently, the height of the saddle must be chosen on the basis of biometric parameters specific to the average driver.

Secondly, the seat height must be defined according to the area of application and the operational requirements of the vehicle. By way of example, saddle-type vehicles for use in urban areas, such as scooters, include saddles which are much lower to the ground in stationary conditions than the saddles of all-terrain vehicles.

Indeed, as a general rule, the suspension system of off-road motorcycles includes long suspensions, with the aim of better absorbing shocks due to the variable nature of the ground. As a result, the saddle is positioned very high in relation to the ground.

Further, high seats in off-road motorcycles allow the rider to appropriately alter his or her weight distribution on the vehicle and thus to safely and conveniently control the vehicle.

Furthermore, the frames of off-road motorcycles and therefore their saddles are positioned at a great distance from the ground, in order to prevent the frame from hitting the ground in the event of complete compression of the suspensions.

Although the height of the saddle should be calculated taking into account at least some of the needs mentioned above, it is clear that the height of the saddle fixed at the design stage cannot correspond to the biometric parameters of all types. of drivers. For example, the saddle position of off-road motorcycles is generally suboptimal for shorter people.

In particular, a reduction in the height of the saddle by changing the length of the levers of the suspension system is known. However, this static adjustment is irreversible and causes a permanent modification of the suspension system of the saddle-type vehicle, the dynamic behavior of which is consequently altered.

Therefore, there is a need in the industry for a saddle-type vehicle in which the saddle height can be dynamically changed based on the driver's needs and biometrics.

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 and a rear wheel, which are adapted to move said frame relative to the ground along a direction of progression of said vehicle;

- A saddle, which is adapted to be used as a seat by the driver and/or a passenger and is connected to said frame at a height relative to the ground; said height being measured along a second direction perpendicular to the ground; and

- a suspension system having total rigidity and coupling said frame with said front and rear wheels in a variable relative position with respect to each other along said second direction, said relative position being dependent on the loads acting on said saddle-type vehicle and said total stiffness, said height being dependent on said relative position.

Said suspension system comprises at least one mechanical-hydropneumatic hybrid suspension having an equivalent stiffness, said total stiffness depending on said equivalent stiffness, and said hybrid suspension comprising, in turn, 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 being operatively coupled to each other and defining said equivalent stiffness, said equivalent stiffness being variable as a function of said relative position.

The saddle-type vehicle is characterized in that it further comprises an adjustment system configured to automatically adjust said second stiffness according to one or more parameters of said vehicle, so as to modify said height.

According to one embodiment, the saddle-type vehicle may further comprise a control unit operatively connected to said adjustment system, said control unit being configured to receive said one or more parameters and to send an instruction to adjusting said adjustment system based on said one or more parameters to adjust said second stiffness.

According to one embodiment, the saddle-type vehicle can be movable at least between a lowered position, in which said height is equal to a first height value, and a raised position, in which said height is equal to a second value height, said second height value being greater than said first height value, and the saddle-type vehicle may be further characterized in that said control unit is configured to send said adjustment command to lower said second stiffness to set said saddle-type vehicle in said lowered position and to send said adjustment instruction to raise said second stiffness to set said saddle-type vehicle in said raised position based on said one or more parameters.

According to one embodiment, one or more parameters may be adapted to provide an indication that said saddle-type vehicle, in use, is stationary or is in an imminent state of shutdown, and the saddle-type vehicle may be characterized further in that said control unit is configured to send said adjustment command to lower said second stiffness to adjust said saddle-type vehicle to said lowered position when said one or more parameters provide, in use, said indication that said saddle-type vehicle is stationary or in said near-stop state.

According to one embodiment, said hybrid suspension may comprise a damper, which is suitable for damping the oscillations of said elastic element and/or of said hydropneumatic spring, and said hydropneumatic spring may comprise a first part which is spaced from said damper, and a second part which is mounted coaxially around said damper.

In this embodiment, said hydropneumatic spring may further comprise:

- a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second stiffness;

- a second chamber and a third chamber, which are fluidically connected with each other and contain an incompressible fluid;

said first chamber and said second chamber being formed within an internal volume of said first part, said third chamber being formed at said second part, said first part comprising, in turn, a partition wall, which sealably separates said first chamber from said second chamber, said separating wall being able to slide or deform inside said internal volume so as to cause a variation of said pressure, said separating wall being able to slide or deform according to said internal 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 adapted to modify said internal volume so as to cause said partition wall to slide and a automatic actuation means for driving said adjustment device.

According to one embodiment, said adjustment device can be movable between a retracted position, in which said internal volume is equal to a first value, and an extended position, in which said internal volume is equal to a second value, said second value being less than said first value, said automatic actuating means comprising an electric motor, which is configured to actuate said adjustment device between said retracted position and said extended position.

According to one embodiment, said electric motor may be a stepper motor and said adjustment device may be a screw element operatively connected to said stepper motor.

According to one embodiment, the saddle-type vehicle may further comprise a user interface, which is operatively connected to said control unit, said user interface being configured to receive a user instruction to change said height of said saddle.

This object is also achieved by a method for controlling a saddle-type vehicle, said saddle-type vehicle comprising:

- a frame ;

- a front wheel and a rear wheel, which are adapted to move said frame relative to the ground along a direction of progression of said vehicle;

- A saddle, which is adapted to be used as a seat by the driver and/or a passenger and is connected to said frame at a height relative to the ground; said height being measured along a second direction perpendicular to the ground; and

- a suspension system having total rigidity and coupling said frame with said front and rear wheels in a variable relative position with respect to each other along said second direction, said relative position being dependent on the loads acting on said saddle-type vehicle and said total stiffness, said height being dependent on said relative position.

Said suspension system comprises at least one mechanical-hydropneumatic hybrid suspension having an equivalent rigidity, said total rigidity depending on said equivalent rigidity.

Said hybrid suspension in turn comprises at least one elastic element having a first rigidity and at least one hydropneumatic spring having a second rigidity, said elastic element and said hydropneumatic spring being operatively coupled to each other and defining said rigidity equivalent, said equivalent stiffness being variable as a function of said relative position.

The method is characterized in that it comprises the steps consisting in:

i) detecting one or more parameters of said saddle-type vehicle; and

ii) automatically adjusting said second stiffness by means of an adjustment system of said saddle-type vehicle as a function of said one or more parameters, in order to vary said height.

According to one embodiment, the control method may further comprise the additional step of:

iii) sending said adjustment system an adjustment instruction by means of a control unit of said saddle-type vehicle to adjust said saddle-type vehicle to at least one of continuous positions between a lowered position and a raised position of said saddle type vehicle, said lowered position corresponding to a first height value of said height and said raised position corresponding to a second height value of said height; said second height value being greater than said first height value.

According to one embodiment, the control method may further comprise the additional step of:

iv) sending said adjustment system said adjustment instruction via said control unit to adjust said saddle-type vehicle to said lowered position when said one or more parameters provide an indication that said saddle-type vehicle is stationary or is in an imminent shutdown state.

According to one embodiment, the control method may further comprise the additional step of:

v) varying an internal volume of a first part of said hydropneumatic spring by means of an adjustment device of said adjustment system, which is driven by an automatic actuation means of said adjustment system;

said hybrid suspension further comprising a shock absorber, which is suitable for damping the oscillations of said elastic element and/or of said hydropneumatic spring;

said hydropneumatic spring comprising said first part, which is spaced from said shock absorber, and a second part, which is mounted coaxially around said shock absorber;

said hydropneumatic spring further comprising:

- a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second stiffness;

- a second chamber and a third chamber, which are fluidically connected with each other and contain an incompressible fluid;

said first chamber and said second chamber being formed inside said internal volume of said first part; said third chamber being formed at said second part;

said first part comprising, in turn, a partition wall, which sealably separates said first chamber from said second chamber; said separation wall being able to slide or deform inside said internal volume so as to cause a variation of said pressure;

said separation wall being able to slide or deform according to said internal volume and the volume of said incompressible fluid transferred between said second chamber and said third chamber.

According to one embodiment, the control method may further comprise the additional step of:

vi) moving said adjustment device between a retracted position and an extended position via an electric motor of said automatic actuating means, said retracted position corresponding to a first value of said internal volume and said extended position corresponding to a second value of said internal volume; said second value being less than said first value.

A preferred non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

- Figures 1 and 2 are side views of a saddle-type vehicle according to the present invention in two respective operational positions;

- Figures 3 and 4 are side views on a greatly enlarged scale of a detail of the saddle-type vehicle of Figures 1 and 2, respectively; and

- Figures 5 and 6 are respective diagrams illustrating the characteristic curves of a saddle-type vehicle suspension in the operating positions of Figures 1 and 2, respectively.

Referring to Figures 1 and 4, reference numeral 1 indicates a saddle-type vehicle, which can be adjusted in height.

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

In the remainder of this description, expressions such as “rear”, “front” and the like are used with reference to a normal direction of progression X of the vehicle 1 shown in the appended figures.

As shown on the , the vehicle 1 substantially comprises:

- a frame 2;

- a front wheel 3 and a rear wheel 4, which are adapted to move the frame 2 relative to the ground G along a direction of progression X;

- A saddle 5 intended to be used as a seat by a driver and/or a passenger; and

- a suspension system 6 having a total stiffness K and a coupling frame 2 with wheels 3, 4 in a variable relative position with respect to each other.

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 detail, the saddle 5 is mounted on the frame 2 at a height h relative to the ground G. In more detail, the height h is the distance between the seat of the saddle 5 and the ground G along a direction Z which is perpendicular to the ground G.

The height h is variable depending on the relative position between the frame 2 and the wheels 3, 4.

In detail, the relative position of the wheels 3, 4 with respect to the frame 2 depends on the loads acting on the vehicle 1 and the total stiffness K.

According to Hooke's law, it is possible to deduce that the lower the total stiffness K, the lower the height h of the saddle 5 is under the same loading conditions of the vehicle 1.

It is also possible to define a thickness t of the saddle 5 as the maximum distance between the seat of the saddle 5 and the frame 2 along the direction Z (FIGS. 1 and 2).

The suspension system 6 comprises a plurality of suspensions, one or more of which is/are a mechanical-hydropneumatic hybrid suspension 15.

Such a hybrid suspension 15 is known, by way of example, from the documents 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, which are mounted on the rear wheel 4. However, the suspension system 6 can comprise hybrid suspensions 15 at both the rear and front wheels. 3, 4.

The rest of the 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 one another.

The hybrid suspension 15 comprises, in detail, an elastic element 7 having a stiffness k1 and a hydropneumatic spring 8 having a stiffness k2 (FIGS. 3 and 4).

Preferably, the hybrid suspension 15 further comprises a shock absorber 11 constrained at least indirectly between the rear wheel 4 and the frame 2 and defining an axis A. The shock absorber 11 is adapted to damp the oscillations of the elastic element 7 and/or or the hydropneumatic spring 8.

In the embodiment shown, damper 11 is a viscous damper. In a known way, 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 damper 11 may further comprise a gas chamber (containing for example nitrogen) and a reservoir of viscous fluid. Thus, the damper 11 will be adapted to damp the oscillations of the elastic element 7 and/or of the hydropneumatic spring 8 also by the compression and expansion of the gas contained in the gas chamber.

Alternatively, the hybrid suspension 15 may not include the shock absorber 11, and the hydropneumatic spring 8 may also be adapted to dampen the oscillations of the elastic element 7.

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. In detail, the equivalent stiffness keq of the one or more hybrid suspensions 15 and the stiffness of any other suspension of the suspension system 6 defines a total stiffness K.

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.

In detail, the greater the equivalent deformation xeq, the lower the height h.

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 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 (Figures 3 and 4).

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

Preferably, the elastic element 7 is preloaded, in order to avoid vibration noise.

In addition, as shown in Figures 3 and 4, 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 is not crossed by it. ci, and the second part 17 is mounted coaxially around the damper 11.

In addition, each hydropneumatic spring 8 includes:

- a first chamber 20, which contains a gas at a pressure p;

- a second chamber and a third chamber, which are fluidically connected with each other and contain an incompressible fluid;

In detail, the second 22 and third 23 chambers are fluidically connected with each other through a fluidic line. Such a fluidic line can be a deformable pipe.

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 shown in Figures 3 and 4, first and second chambers 20, 22 are formed inside the internal 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 seals the first chamber 20 from the second chamber 22 and which can slide or deform inside the internal volume V along a B direction.

As shown in Figures 3 and 4, the partition wall 21 is a piston having a cross section Ω perpendicular to the direction B. Alternatively, the partition wall 21 may be a deformable membrane.

In detail, the sum of the volume of the first chamber 20 and the volume of the second chamber 22 being equal to the internal volume V, the sliding of the partition wall 21 along the direction B 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 partition wall 21 can slide 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.

It should be noted that the volume of the first chamber 20 cannot be reduced below a minimum volume value, which is greater than zero.

As shown in Figures 3 and 4, the second part 17 of the hybrid suspension 15 comprises:

- A first element 24, which is mounted integrally and coaxially on the damper 11; and

- a second element 25, which is adapted to cooperate with the elastic element 7 and is mounted coaxially to the damper 11 in a movable manner with respect to the first element 24.

The second element 25 is arranged radially outward from the first element 24. In detail, the second element 25 includes a radially inner surface 26, which faces the first element 24 (FIGS. 3 and 4).

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 HAS.

As the third chamber 23 contains an incompressible fluid, any relative movement between the first element 24 and the second element 25 causes a transfer of the incompressible fluid between the second chamber 22 and the third chamber 23. Similarly, any variation in the internal 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.

Advantageously, the vehicle 1 further comprises an adjustment system 9 configured to automatically adjust the stiffness k2 of the hydropneumatic suspension 8 as a function of one or more parameters π of the vehicle 1, with the aim of modifying the height h.

Indeed, as mentioned above, under the same loading conditions of the vehicle 1, the height h depends on the relative position between the wheels 3, 4 and the frame 2. This relative position depends, in turn, on the rigidity total K and, in particular, the equivalent stiffness keq of the one or more hybrid suspensions 15. Furthermore, an equivalent stiffness keq depends, for at least part of the relative displacement between the frame 2 and the wheels 3, 4, on the rigidity k2.

The stiffness k2 is adjusted automatically, in detail, by modifying the internal volume V of the first part 16. Indeed, as will be described later, a variation of the internal volume V corresponds to a variation of the threshold pressure p0 , which is directly proportional to the stiffness k2.

As a consequence of the variation of the stiffness k2 and under the same loading conditions of the vehicle 1, the vehicle 1 can be moved at least between a lowered position ( ), in which the height h is equal to a value h1, and a high position ( ), in which the height h is equal to a value h2, which is greater than the value h1.

The value h1 is chosen so as to make the saddle 5 accessible to drivers of short stature and/or to allow the driver to place both feet on the ground G when the vehicle 1 is stationary or in an imminent stop state.

In particular, the saddle-type vehicle 1 is stationary when its speed parallel to the direction of progress X is equal to zero. Thus, the vehicle 1 is stationary when it is parked or, for example, when stopped at a red light. On the other hand, the saddle-type vehicle 1 is in the imminent stop condition when its speed parallel to the direction of progress X is gradually reduced and is equal to or less than a speed threshold.

In the embodiment shown, the h1 value is less than the h2 value by 40 mm. In addition, by way of example, the speed threshold can be set at 5 m/s.

Preferably, the vehicle 1 is set in the lowered position when it is stationary or in the state of imminent stop and when it is unloaded, that is to say without driver or passenger riding it and without no other charge is borne by him.

Furthermore, theoretically, the vehicle 1 is set in the elevated position when it moves in the direction of travel X and is unloaded.

The vehicle 1 further comprises a control unit 10, which is operationally connected to the adjustment system 9. In detail, the control unit 10 is configured to receive parameters π and to send an adjustment instruction to the adjustment system 9 on the basis of the parameters π, in order to adjust an equivalent stiffness keq.

In particular, as already explained above, an adjustment instruction to lower the stiffness keq causes a decrease in the height h, while an adjustment instruction to raise the equivalent stiffness keq causes an increase in the height h.

The one or more parameters π provide an indication that the saddle type vehicle 1 is stationary or is in the state of imminent stop.

The parameters π can comprise the speed of the vehicle 1 parallel to the direction of progression X and/or an indication of the gear engaged.

In addition, the vehicle 1 includes foot plates or footrests, which are adapted to support the driver's feet when the vehicle 1 is moving in the direction of travel X. In particular, the parameters π may include an indication that the driver's feet are not placed on the foot plates/pegs. This is based on the fact that at least one foot of the driver is generally positioned on the ground G and is not positioned on the footplates/footrests when the vehicle 1 is stationary or in the state of imminent stop.

The adjustment system 9 comprises, in detail, an adjustment device 30, which is adapted to move inside the first part 16 in order to modify the internal volume V. The adjustment system 9 comprises in further an automatic actuation means 31 for driving the adjustment device 30.

The adjustment device 30 is movable between a retracted position ( ), in which the internal volume V is equal to a first value V1, and an extended position ( ), in which the internal volume V is equal to a second value V2 less than the first value V1. In detail, the automatic actuation means 31 is configured to move the adjustment device 30 between the retracted position and the extended position.

As shown in Figures 3 and 4, adjustment device 30 is configured to move within second chamber 22 and is spaced from first chamber 20.

As mentioned above, the fluid contained inside the second and third chambers 22, 23 being incompressible, any variation in the internal volume V causes a redistribution of the incompressible fluid inside the first part 16 and/or the second part 17.

In particular, if the internal volume V is reduced and the force FΩ is greater than the threshold force F0, the partition wall 21 is adapted to slide along the direction B, in order to reduce the volume of the first chamber 20 and to increase the volume of the second chamber 22. Consequently, the pressure p of the gas contained inside the first chamber 20 is increased. Alternatively or additionally, at least a portion of the incompressible fluid is transferred from second chamber 22 to third chamber 23.

On the contrary, if the internal volume V is increased, the partition 21 is adapted to slide along the direction B, to increase the volume of the first chamber 20 and decrease the volume of the second chamber 22. Consequently, the pressure p of the gas contained inside the first chamber 20 is reduced. Alternatively or additionally, at least a portion of the incompressible fluid is transferred from third chamber 23 to second chamber 22.

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 is reduced if the gas contained in the first chamber 20 is dilated.

In particular, the pressure threshold p0 is equal to a value p01 when the volume V is equal to the value V1, and to a value p02 when the volume V is equal to the value V2.

Furthermore, since the threshold force F0 depends on the threshold pressure p0 and the extension of the cross section Ω is not variable, the threshold force F0, when the threshold pressure p0 is equal to a value p01, is less than the threshold force F0 when the pressure threshold p0 is equal to a value p02. Thus, the volume of the first chamber 20 can be compressed more easily when the volume V is equal to the value V1 than when the volume V is equal to the value V2.

Furthermore, the stiffness k2 of the hydropneumatic spring 8 being directly proportional to the threshold value p0, the stiffness k2, when the pressure threshold p0 is equal to the value p01, is less than the stiffness k2 when the pressure threshold p0 is equal to the value p02.

In particular, the automatic actuation means 31 comprises an electric motor 32. In the embodiment shown, the electric motor 32 is a stepping motor and the adjustment device 30 is a screw element operatively connected to the stepper motor 32. In detail, the electric motor 32 is configured to cause the adjustment device 30 to slide parallel to the direction B between the retracted position and the extended position.

In more detail, the adjustment device 30, in the retracted position, extends for a length L1 inside the internal volume V and causes the volume V to be equal to the value V1 ( ); the adjustment device 30, in the extended position, extends over a length L2 inside the internal volume V and causes the volume V to be equal to the value V2 ( ). Length L2 is greater than length L1.

The characteristic curve of the hybrid suspension 15 when the actuator 30 is in the retracted position is illustrated in the . In detail, the is a graph of the force applied to the hybrid suspension 15 (vertical axis of the graph) as a function of the equivalent deformation xeq (horizontal axis of the graph).

As is known, the equivalent stiffness keq corresponds to the slope of the characteristic curve shown on the .

The characteristic curve of the hybrid suspension 15 represented on the comprises a first section Ia and a second section IIa. The first and second sections Ia, IIa are linear or substantially linear and have respective distinct slopes, which correspond to two respective different values of equivalent stiffness keq. In particular, an equivalent stiffness keq at the level of the first section Ia is less than an equivalent stiffness keq at the level of the second section IIa.

The first section Ia extends between the origin O of the reference system and a point S, which is defined by a value xeqS of equivalent deformation xeq; the second section IIa extends between the point S and a point T, which is defined by a value xeqT of equivalent deformation xeq.

In detail, the origin O is defined by a null value of equivalent deformation xeq. However, the origin coordinate O along the vertical axis can be different from zero, for example equal to the preload of the elastic element 7.

When the equivalent deformation xeq is between zero and the value xeqS, the hydropneumatic spring 8 operates and the equivalent stiffness keq is substantially equal to the stiffness k2.

In particular, when the equivalent deformation xeq is equal to zero, the pressure p is equal to the value p01; when the equivalent deformation xeq is between zero and the value xeqS, the pressure p is greater than the value p01 and the volume of the first chamber 20 is greater than the minimum volume value; when the equivalent deformation xeq is equal to the value xeqS, the volume of the first chamber 20 is equal to the minimum volume value.

When the equivalent deformation xeq is between the value xeqS and the value xeqT, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1.

It is also possible to define a point H1 whose abscissa xeqH1 corresponds to the value h1 of height h and whose ordinate corresponds to the weight of frame 2. In detail, when the equivalent deformation xeq is equal to xeqH1, the vehicle 1 is in the lowered position.

It is also possible to define a point Q, whose abscissa xeqQ corresponds to a height value h, which is lower than the value h1 (that is to say that the saddle 5 is closer to the ground G) and whose ordinate corresponds to the condition in which the driver straddles the saddle 5.

The characteristic curve of the hybrid suspension 15 when the actuator 30 is in the extended position is illustrated in the . Just as the , the is a graph of the force applied to the hybrid suspension 15 as a function of its equivalent deformation xeq.

In particular, the graphs of Figures 5 and 6 share the same reference unit and the same scale. Accordingly, corresponding points on the respective horizontal axes of Figures 5 and 6 indicate the same equivalent strain value xeq. The same is true for the respective vertical axes of Figures 5 and 6.

The characteristic curve shown on the comprises a first section Ib, a second section IIb and a third section IIIb.

The first section Ib extends between the origin O of the reference system and a point U, which is defined by a value xeqU of equivalent deformation xeq; the second section IIb extends between the point U and a point V, which is defined by a value xeqV of equivalent deformation xeq; the third section IIIb extends between the point V and a point Z, which is defined by a value xeqZ of equivalent deformation xeq.

When the equivalent deformation xeq is between zero and a value xeqU, 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 xeqU and a value xeqV, 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 xeqV and a value xeqZ, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness k1.

In particular, when the equivalent deformation xeq is between zero and the value xeqU, the pressure p is equal to the value p02; when the equivalent deformation xeq is between the value xeqU and a value xeqV, the pressure p is greater than the value p02 and the volume of the first chamber 20 is greater than the minimum volume value; when the equivalent deformation xeq is equal to the value xeqV, the volume of the first chamber 20 is equal to the minimum volume value.

In addition, the slope of the first section Ia is less than the slope of the second section IIb. This is because the stiffness k2 when the actuator 30 is in the retracted position is less than the stiffness k2 when the actuator 30 is in the extended position.

It is also possible to define a point H2 whose abscissa xeqH2 corresponds to the value h2 of height h and whose ordinate corresponds to the weight of frame 2. In detail, when the equivalent deformation xeq is equal to xeqH2, the vehicle 1 is in the raised position.

By comparing the with the , it is possible to easily notice that the xeqH2 value is lower than the xeqH1 value. As a result, the h2 value is less than the h1 value of the height h.

It is also possible to define a point J, whose abscissa xeqJ corresponds to a height value h, which is lower than the value h2 (that is to say that the saddle 5 is closer to the ground G) and whose ordinate corresponds to the condition in which the driver straddles the saddle 5 and the vehicle 1 moves along the direction of progress X. Therefore, in this condition, the vehicle 1 is also loaded by a dynamic load due to soil variability G.

The saddle-type vehicle 1 further comprises a user interface 33, which is operatively connected to the control unit 10 (FIGS. 1 and 2). The user interface 33 is configured to receive a user instruction to modify the height h. The user interface 33 can also be configured to allow the driver to set h1 and/or h2 values.

In particular, the position of vehicle 1 can also be adjusted depending on the presence of a passenger and/or loads on vehicle 1.

Furthermore, the stiffness k1, k2 can be chosen such that the value xeqJ is less than the value xeqH1 of equivalent deformation xeq. In other words, an equivalent stiffness keq can be chosen such that the height h when the vehicle 1 is loaded and moving along the direction of progression X is greater than the value h1 of the height h.

The operation of vehicle 1 is described from a state in which vehicle 1 is stationary and unloaded (for example, vehicle 1 is parked).

In this condition, the adjustment device 30 is in the retracted position and extends the length L1 inside the second chamber 22 ( ). Consequently, the height h is equal to the value h1 and the vehicle 1 is in the lowered position.

In detail, this condition corresponds to point H1 of the characteristic curve represented on the .

The value h1 being chosen so as to make the saddle 5 accessible to drivers of small stature or adjusted by the driver, the driver can easily straddle the saddle 5.

After the driver has straddled the saddle 5, the suspension system 6 is loaded by the weight of the driver and the equivalent deformation xeq of the hybrid suspension 15 increases.

This condition corresponds to the point Q of the characteristic curve represented on the . Therefore, the height h becomes less than the value h1.

When the vehicle 1 begins to advance along the direction X, the parameters π send to the control unit 10 the indication that the vehicle 1 is not stationary, nor in the state of imminent stop.

The control unit 10 instructs the adjustment device 30 to slide from the retracted position ( ) to the extended position ( ) based on the parameters π. In detail, the adjustment device 30 slides parallel to the direction B and takes the length L2 inside the second chamber 22.

In the theoretical condition in which the vehicle 1 is unloaded and moves along the direction of progression X without any dynamic load acting on it, the equivalent deformation xeq of the hybrid suspension 15 would be equal to xeqH2. Therefore, the height h would equal the value h2 and the vehicle 1 would be in the raised position.

However, since the vehicle 1 moving along the direction of travel X is in fact loaded at least by the weight of the driver and the dynamic loads due to the variable nature of the ground G, an equivalent deformation xeq of the hybrid suspension 15 is equal to the value xeqJ (see point J of the ).

In detail, when the equivalent deformation xeq is equal to xeqJ, the height h is less than the value h2. However, comparing the with the , it is possible to note that the value xeqJ of the is less than the xeqQ value of the .

Therefore, when the vehicle 1 is loaded and travels along the X direction, the height h is greater when the adjuster 30 is in the extended position ( ) only when the adjustment device 30 is in the retracted position ( ).

When the vehicle 1 slows down along the direction of travel X or comes to a complete stop, parameters π send to the control unit 10 the indication that the vehicle 1 is in the state of imminent stop or is stationary.

The control unit 10 instructs the adjuster 30 to slide from the extended position ( ) to the retracted position ( ) based on the parameters π.

As a result, the internal volume V becomes equal to the value V1 and the equivalent deformation xeq becomes equal to the value xeqQ, which corresponds to a height value h which is less than the value h1. Therefore, the driver can put both feet on the ground G while straddling the saddle 5.

The advantages of the saddle type vehicle 1 and the saddle type vehicle control method according to the invention will become apparent from the above description.

Given that the vehicle 1 comprises an adjustment system 9 configured to automatically adjust the rigidity k2 of the hydropneumatic spring 8, the height h of the saddle 5 can be modified according to the necessities and the biometric parameters of the driver. In particular, unlike the static saddle height adjustment discussed in the introductory part of this description, the height h can be changed dynamically based on the parameters π. Consequently, the height h can be adjusted without permanently altering the dynamic behavior of the suspension system 6.

Furthermore, the vehicle 1 can be moved automatically at least between the lowered position and the raised position. Consequently, on the one hand, the saddle 5 is easily accessible to the driver when the vehicle 1 is stationary. On the other hand, the value h2 can be chosen such that the height h is compatible with the field of application and the operational requirements of the vehicle 1, when the vehicle 1 moves along the direction of progress X.

Moreover, since the value h2 can be chosen substantially independently of the value h1, the thickness t can be increased so as to improve driver comfort. Indeed, a greater thickness t corresponds to a thicker padding of the saddle 5 and, consequently, to a greater capacity of the saddle 5 to dampen the bumps and vibrations transmitted to the driver.

Moreover, as the vehicle 1 comprises a user interface 33, the height h can be modified by the driver according to the needs and the biometric parameters of the driver.

In addition, the height h can be varied precisely also depending on the particular loading conditions of vehicle 1, for example when a passenger or loads are present on vehicle 1.

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

In particular, the suspension system 6 could comprise hybrid suspensions 15 different from each other. For example, the hybrid suspensions 15 mounted on the front wheel 3 can have a different stiffness k2 from the hybrid suspensions 15 mounted on the rear wheel 4.

Claims (13)

Saddle-type vehicle (1) comprising:
- a frame (2);
- a front wheel (3) and a rear wheel (4), which are adapted to move said frame (2) relative to the ground (G) along a direction of progression (X) of said vehicle (1);
- a saddle (5), which is adapted to be used as a seat by the driver and/or a passenger and which is mounted on said frame (2) at a height (h) with respect to the ground (G); said height (h) being measured along a second direction (Z) perpendicular to the ground (G); and
- a suspension system (6) having a total stiffness (K) and coupling said frame (2) with said front and rear wheels (3, 4) in a variable relative position with respect to each other along said second direction (Z); said relative position depending on the loads acting on said saddle type vehicle (1) and said total stiffness (K); said height (h) depending on said relative position;
said suspension system (6) comprising at least one mechanical-hydropneumatic hybrid suspension (15) having an equivalent stiffness (keq); said total stiffness (K) depending on said equivalent stiffness (keq);
said hybrid suspension (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 said equivalent stiffness (keq); said equivalent stiffness (keq) being variable as a function of said relative position;
characterized in that it further comprises an adjustment system (9) configured to automatically adjust said second stiffness (k2) as a function of one or more parameters (π) of said vehicle (1), so as to modify said height (h).
Saddle-type vehicle according to claim 1, characterized in that it further comprises a control unit (10) operatively connected to said adjustment system (9);
said control unit (9) being configured to receive said one or more parameters (π) and to send an adjustment instruction to said adjustment system (9) on the basis of said one or more parameters (π) in order to adjust said second stiffness (k2).
A saddle-type vehicle according to claim 2, wherein said saddle-type vehicle (1) is movable at least between a lowered position, wherein said height (h) is equal to a first height value (h1), and a raised position, in which said height (h) is equal to a second height value (h2); said second height value (h2) being greater than said first height value (h1);
characterized in that said control unit (10) is configured to send said adjustment instruction to lower said second stiffness (k2) to adjust said saddle-type vehicle (1) in said lowered position and to send said instruction to adjusting to raise said second stiffness (k2) to set said saddle-type vehicle (1) in said raised position as a function of said one or more parameters (π).
Saddle-type vehicle according to claim 3, characterized in that said one or more parameters (π) are adapted to provide an indication that said saddle-type vehicle (1), in use, is stationary or in a state of imminent shutdown;
characterized in that said control unit (10) is configured to send said adjustment command to lower said second stiffness (k2) to adjust said saddle-type vehicle (1) to said lowered position when said one or more parameters (π) provide, in use, said indication that said saddle-type vehicle (1) is stationary or is in said state of imminent stop.
A saddle-type vehicle according to any preceding claim, wherein said hybrid suspension (15) further comprises a damper (11), which is adapted to dampen oscillations of said elastic member (7) and/or said hydropneumatic spring (8);
said hydropneumatic spring (8) comprising a first part (16), which is spaced from said shock absorber (11) and a second part (17), which is mounted coaxially around said shock absorber (11);
said hydropneumatic spring (8) further comprising:
- 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 with each other and contain an incompressible fluid;
said first chamber (20) and said second chamber (22) being formed inside an internal volume (V) of said first part (16); said third chamber (23) being formed at said second part (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 internal volume (V) so as to cause a variation of said pressure (p);
said partition wall (21) being able to slide or deform 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) suitable for modifying said internal volume (V) so as to cause the sliding of said partition wall (21); and
- automatic actuation means (31) for driving said adjustment device (30).
Saddle-type vehicle according to claim 5, characterized in that said adjustment device (30) is movable between a retracted position, in which said internal volume (V) is equal to a first value (V1), and a position extended, wherein said internal volume (V) is equal to a second value (V2); said second value (V2) being lower than said first value (V1);
said automatic actuating means (31) comprising an electric motor (32), which is configured to actuate said adjustment device (30) between said retracted position and said extended position.
Saddle type vehicle according to claim 6, characterized in that said electric motor (32) is a stepper motor and said adjusting device (30) is a screw member operatively connected to said stepper motor ( 32).
Saddle-type vehicle according to any one of claims 2 to 7, characterized in that it comprises a user interface (33), which is operatively connected to said control unit (10);
said user interface (33) being configured to receive a user instruction to modify said height (h) of said saddle (5).
A control method for controlling a saddle type vehicle (1); said saddle-type vehicle (1) comprising:
- a frame (2);
- a front wheel (3) and a rear wheel (4), which are adapted to move said frame (2) relative to the ground (G) along a direction of progression (X) of said vehicle (1);
- a saddle (5), which is adapted to be used as a seat by the driver and/or a passenger and which is mounted on said frame (2) at a height (h) with respect to the ground (G); said height (h) being measured along a second direction (Z) perpendicular to the ground (G); and
- a suspension system (6) having a total stiffness (K) and coupling said frame (2) with said front and rear wheels (3, 4) in a variable relative position with respect to each other along said second direction (Z); said relative position depending on the loads acting on said saddle type vehicle (1) and said total stiffness (K); said height (h) depending on said relative position;
said suspension system (6) comprising at least one mechanical-hydropneumatic hybrid suspension (15) having an equivalent stiffness (keq); said total stiffness (K) depending on said equivalent stiffness (keq);
said hybrid suspension (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 said equivalent stiffness (keq); said equivalent stiffness (keq) being variable as a function of said relative position;
said method being characterized in that it comprises the steps of:
i) detecting one or more parameters (π) of said saddle type vehicle (1);
ii) automatically adjusting said second stiffness (k2) by means of an adjustment system (9) of said saddle-type vehicle (1) according to said one or more parameters (π), in order to modify said height (h) .
Control method according to claim 9, characterized in that it further comprises the step consisting in:
iii) sending to said adjustment system (9) an adjustment instruction by means of a control unit (10) of said saddle-type vehicle (1) to adjust said saddle-type vehicle (1) in the one of continuous positions at least between a lowered position and a raised position of said saddle type vehicle (1);
said lowered position corresponding to a first height value (h1) of said height (h) and said raised position corresponding to a second height value (h2) of said height (h); said second height value (h2) being greater than said first height value (h1).
Control method according to claim 10, characterized in that it further comprises the step consisting in:
iv) sending to said adjustment system (9) said adjustment instruction via said control unit (10) to adjust said saddle-type vehicle (1) to said lowered position when said one or more parameters ( π) provide an indication that said saddle-type vehicle (1) is stationary or in an imminent stop state.
Control method according to any one of Claims 9 to 11, characterized in that it comprises the step consisting in:
v) varying an internal volume (V) of a first part (16) of said hydropneumatic spring (8) through an adjustment device (30) of said adjustment system (9), which is driven by means of automatic actuation (31) of said adjustment system (9);
said hybrid suspension (15) further comprising a damper (11), which is suitable for damping the oscillations of said elastic element (7) and/or of said hydropneumatic spring (8);
said hydropneumatic spring (8) comprising said first part (16), which is spaced from said damper (11) and a second part (17), which is mounted coaxially around said damper (11);
said hydropneumatic spring (8) further comprising:
- 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 with each other and contain an incompressible fluid;
said first chamber (20) and said second chamber (22) being formed inside an internal 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 internal volume (V) so as to cause a variation of said pressure (p);
said partition wall (21) being able to slide or deform depending on said internal volume (V) and the volume of said incompressible fluid transferred between said second chamber (22) and said third chamber (23).
Control method according to Claim 12, characterized in that it comprises the additional step consisting in:
vi) moving said adjuster (30) between a retracted position and an extended position via an electric motor (32) of said automatic actuating means (9);
said retracted position corresponding to a first value (V1) of said internal volume (V) and said extended position corresponding to a second value (V2) of said internal volume (V); said second value (V2) being lower than said first value (V1).