VEHICLE WITH ADJUSTABLE HEIGHT SEAT AND ITS CONTROL METHOD

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 travel (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) includes 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 abbreviation: Figure 1

Description

Title of the invention: Adjustable-height saddle-type vehicle and its control method. Technical field

[0001] The present invention relates to a seat-type vehicle with a height adjustment and an associated control method. technological BACKGROUND

[0002] Saddle-type vehicles are known, comprising: - 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 rotational manner around its own second axis; - a suspension system coupling the frame with the wheels in a variable relative position to each other.

[0003] 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.

[0004] In addition, saddle-type vehicles can be configured in various ways, for example as motorcycles, as scooters or as mopeds, and are also known to have two front or rear wheels, which are mounted in such a way as to be inclined relative to the frame.

[0005] Saddle-type vehicles further include a saddle for the driver and any passenger, which is arranged at a certain height above the ground. In detail, this height – also known as “ground access” – varies depending on the relative position between the frame and the wheels.

[0006] In general, the height of the saddle when the vehicle is stationary is defined at the design stage as part of a compromise between various functional and aesthetic requirements.

[0007] First, when the vehicle is stationary, the saddle must be positioned so that it is easily accessible to the driver. Furthermore, 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 saddle height must be chosen based on biometric parameters specific to the average driver.

[0008] Secondly, the seat height must be defined according to the field of application and the operational requirements of the vehicle. For example, Saddle-type vehicles intended for use in urban areas, such as scooters, include saddles that are much closer to the ground in stationary conditions than the saddles of off-road vehicles.

[0009] Indeed, as a general rule, the suspension system of off-road motorcycles includes long suspension arms, in order to better absorb shocks due to the varying nature of the ground. As a result, the seat is positioned very high relative to the ground.

[0010] In addition, high seats in off-road motorcycles allow the driver to appropriately modify the distribution of their weight on the vehicle and thus to control the vehicle safely and conveniently.

[0011] Furthermore, off-road motorcycle frames and consequently their seats are positioned at a great distance from the ground, in order to prevent the frame from hitting the ground in the event of full compression of the suspensions.

[0012] Although the saddle height should be calculated taking into account at least some of the needs mentioned above, it is clear that the saddle height fixed at the design stage cannot correspond to the biometric parameters of all types of riders. For example, the saddle position of off-road motorcycles is generally suboptimal for shorter people.

[0013] In particular, a reduction in seat height by modifying the length of the suspension system levers is known. However, this static adjustment is irreversible and causes a permanent modification of the suspension system of the saddle-type vehicle, whose dynamic behavior is consequently altered.

[0014] Therefore, there is a need in the industry to obtain a saddle-type vehicle, in which the height of the saddle can be dynamically modified based on the needs and biometric parameters of the driver. DESCRIPTION OF THE INVENTION

[0015] It is an object of the present invention to provide a saddle-type vehicle, making it possible to satisfy at least one of the needs mentioned above in a simple and economical manner.

[0016] This goal 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 for use as a seat by the driver and / or a passenger and is attached to said frame at a height above 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 to each other the other along said second direction, said relative position being dependent on the loads acting on said saddle-type vehicle and said total rigidity, said height being dependent on said relative position.

[0017] Said suspension system comprises at least one mechanical-hydropneumatic hybrid suspension having 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 operationally coupled to each other and defining said equivalent stiffness, said equivalent stiffness being variable as a function of said relative position.

[0018] The saddle-type vehicle is characterized in that it further comprises an adjustment system configured to automatically adjust said second rigidity according to one or more parameters of said vehicle, so as to modify said height.

[0019] According to one embodiment, the saddle-type vehicle may further include a control unit operationally connected to said adjustment system, said control unit being configured to receive said one or more parameters and to send an adjustment instruction to said adjustment system based on said one or more parameters in order to adjust said second stiffness.

[0020] According to one embodiment, the saddle-type vehicle can be mobile 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 height value, said second height value being greater than said first height value, and the saddle-type vehicle can be further characterized in that said control unit is configured to send said adjustment instruction to lower said second stiffness in order to adjust said saddle-type vehicle in said lowered position and to send said adjustment instruction to raise said second stiffness in order to adjust said saddle-type vehicle in said raised position according to said one or more parameters.

[0021] 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 a state of imminent stop, and the saddle-type vehicle may be further characterized in that said control unit is configured to send said adjustment instruction to lower said second stiffness in order to set said saddle-type vehicle in said lowered position when said one or more parameters provide, in use, said indication that said saddle-type vehicle is stationary or is in said state of imminent stop.

[0022] According to one embodiment, said hybrid suspension may include a damper, which is adapted to dampen the oscillations of said elastic element and / or said hydropneumatic spring, and said hydropneumatic spring may include a first part which is spaced from said damper, and a second part which is mounted coaxially around said damper.

[0023] 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 rigidity; - a second chamber and a third chamber, which are fluidly connected to each other and contain an incompressible fluid;

[0024] said first chamber and said second chamber being formed within an internal volume of said first part, said third chamber being formed at the level of said second part, said first part comprising, in turn, a separating wall, which hermetically separates said first chamber from said second chamber, said separating wall being able to slide or deform within 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.

[0025] In this embodiment, the saddle-type vehicle can further be characterized in that said adjustment system includes an adjustment device adapted to modify said internal volume so as to cause the sliding of said partition wall and an automatic actuation means to drive said adjustment device.

[0026] According to one embodiment, said adjustment device may 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 actuation means comprising an electric motor, which is configured to actuate said adjustment device between said retracted position and said extended position.

[0027] According to one embodiment, said electric motor may be a stepper motor and said adjustment device may be a screw element operationally connected to said stepper motor.

[0028] According to one embodiment, the saddle-type vehicle may further comprise a user interface, which is operationally connected to said unit of command, said user interface being configured to receive a user instruction to change said saddle height.

[0029] This goal is also achieved by a method of 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 for use as a seat by the driver and / or a passenger and is attached to said frame at a height above 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 of said total rigidity, said height being dependent on said relative position.

[0030] Said suspension system includes at least one mechanical-hydropneumatic hybrid suspension having equivalent rigidity, said total rigidity depending on said equivalent rigidity.

[0031] 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 operationally coupled to each other and defining said equivalent rigidity, said equivalent rigidity being variable according to said relative position.

[0032] The process is characterized in that it comprises the steps of: (i) detect one or more parameters of said saddle-type vehicle; and (ii) automatically adjust said second rigidity by means of an adjustment system of said saddle-type vehicle according to said one or more parameters, in order to vary said height.

[0033] According to one embodiment, the control method may further include the additional step of:

[0034] iii) send said adjustment system an adjustment instruction by means of a control unit of said saddle-type vehicle to adjust said saddle-type vehicle in at least one of the 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.

[0035] According to one embodiment, the control method may further include the additional step of:

[0036] iv) send said adjustment system said adjustment instruction through said control unit to adjust said saddle-type vehicle in said lowered position when said one or more parameters provide an indication that said saddle-type vehicle is stationary or is in a state of imminent stop.

[0037] According to one embodiment, the control method may further include the additional step of:

[0038] v) vary 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;

[0039] said hybrid suspension further comprising a shock absorber, which is adapted to dampen the oscillations of said elastic element and / or said hydropneumatic spring;

[0040] 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;

[0041] said hydropneumatic spring further comprising: - a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second rigidity; - a second chamber and a third chamber, which are fluidly connected to each other and contain an incompressible fluid;

[0042] said first chamber and said second chamber being formed within said internal volume of said first part; said third chamber being formed at the level of said second part;

[0043] said first part comprising, in turn, a separating wall, which hermetically separates said first chamber from said second chamber; said separating wall being able to slide or deform within said internal volume so as to cause a variation of said pressure;

[0044] said partition 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.

[0045] According to one embodiment, the control method may further include the additional step of:

[0046] vi) move said adjustment device between a retracted position and an extended position by means of an electric motor of said actuating means automatic, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] 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 greatly enlarged side views of a detail of the saddle-type vehicle shown in 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 operational positions of Figures 1 and 2, respectively. BEST WAY TO IMPLEMENT THE INVENTION

[0048] Referring to figures 1 and 4, the numerical reference 1 indicates a saddle-type vehicle, which can be adjusted in height.

[0049] In the embodiment shown, the saddle-type vehicle is a motorcycle. Alternatively, the saddle-type vehicle is a scooter or a moped.

[0050] In the remainder of this description, expressions such as "rear", "front" and similar are used with reference to a normal direction of progression X of the vehicle 1 shown in the accompanying figures.

[0051] As shown in [Fig. 1], 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 for use as a seat by a driver and / or a passenger; and - a suspension system 6 having a total rigidity K and a coupling frame 2 with wheels 3, 4 in a variable relative position with respect to each other.

[0052] 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.

[0053] In detail, the saddle 5 is mounted on the frame 2 at a height h relative to the ground G. More specifically, 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.

[0054] The height h is variable depending on the relative position between the frame 2 and the wheels 3, 4.

[0055] 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 rigidity K.

[0056] According to Hooke's law, it is possible to deduce that the lower the total rigidity K, the lower the height h of the saddle 5 is under the same vehicle loading conditions 1.

[0057] 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 (figures 1 and 2).

[0058] The suspension system 6 comprises a plurality of suspensions, one or more of which is / are a hybrid mechanical-hydropneumatic suspension 15.

[0059] Such a hybrid suspension 15 is known, for example, from documents WO-A1-2015155712 and IT-A1-102012902090112 and is marketed by the company Umbria Kinetics under the name AirTender®.

[0060] 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 may comprise hybrid suspensions 15 at both the rear and front wheels 3, 4.

[0061] 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 each other.

[0062] The hybrid suspension 15 comprises, in detail, an elastic element 7 having a stiffness kl and a hydropneumatic spring 8 having a stiffness k2 (figures 3 and 4).

[0063] 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 dampen the oscillations of the elastic element 7 and / or the hydropneumatic spring 8.

[0064] In the embodiment shown, the shock absorber 11 is a viscous shock absorber. In a known manner, the shock absorber 11 comprises a cylinder containing a viscous fluid (for example, oil) and a slider adapted to slide within the cylinder. In detail, the cylinder and the slider are respectively fixed to the frame 2 and the rear wheel 4, or vice versa, and the slider is adapted to slide within the cylinder depending on the relative position between the frame 2 and the rear wheel 4.

[0065] The damper 11 may further comprise a gas chamber (containing, for example, nitrogen) and a viscous fluid reservoir. Thus, the damper 11 will be adapted to dampen the oscillations of the elastic element 7 and / or the hydropneumatic spring 8 also by the compression and expansion of the gas contained in the gas chamber.

[0066] 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.

[0067] The elastic element 7 and the hydropneumatic spring 8 are operationally coupled to each other in series and define an equivalent stiffness keq of the hybrid suspension 15. In detail, the equivalent stiffness keq of one or more hybrid suspensions 15 and the stiffness of any other suspension of the suspension system 6 define a total stiffness K.

[0068] 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.

[0069] In detail, the greater the equivalent deformation xeq, the lower the height h.

[0070] 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.

[0071] 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 a portion thereof. 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 helical spring and is arranged coaxially with respect to the damper 11 (Figures 3 and 4).

[0072] In detail, the elastic element 7 is adapted to cooperate with the shock absorber 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 slider of the shock absorber 11 inside the respective cylinder.

[0073] Preferably, the elastic element 7 is preloaded to avoid vibration noise.

[0074] Furthermore, 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 away from the shock absorber 11 and is not traversed by it, and the second part 17 is mounted coaxially around the shock absorber 11.

[0075] In addition, each hydropneumatic spring 8 comprises: - a first chamber 20, which contains a gas at a pressure p; - a second chamber and a third chamber, which are fluidly connected to each other and contain an incompressible fluid;

[0076] In detail, the second 22 and third 23 chambers are fluidically connected to each other via a fluidic line. Such a fluidic line can be a deformable pipe.

[0077] 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.

[0078] As shown in Figures 3 and 4, the 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.

[0079] The first part 16 includes, in turn, a separating wall 21, which hermetically separates the first chamber 20 from the second chamber 22 and which can slide or deform inside the internal volume V along a direction B.

[0080] As shown in Figures 3 and 4, the separating wall 21 is a piston having a cross-section Q perpendicular to the direction B. Alternatively, the separating wall 21 can be a deformable membrane.

[0081] 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 internal volume V, sliding the separating wall 21 along direction B causes a decrease in the volume of the first chamber 20 and an increase in the volume of the second chamber 22, or vice versa. Furthermore, a decrease (increase) in the volume of the first chamber 20 causes an increase (decrease) in the pressure p of the gas contained within it.

[0082] In general, the separating 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.

[0083] In particular, the separating 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 separating wall 21 a force FQ greater than a threshold force F0 exerted by the gas on the separating wall 21. This threshold force F0 depends, in detail, on a threshold value pO of the pressure p and the extension of the cross-section Q of the separating wall 21.

[0084] Furthermore, it is possible to demonstrate experimentally that the stiffness k2 of the hydropneumatic spring 8 is directly proportional to the pressure p and, in particular, to the threshold value pO.

[0085] 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.

[0086] As shown in Figures 3 and 4, the second part 17 of the hybrid suspension 15 comprises: - a first element 24, which is mounted in one piece and coaxially on the shock absorber 11; and - a second element 25, which is adapted to cooperate with the elastic element 7 and is mounted coaxially to the shock absorber 11 in a movable manner relative to the first element 24.

[0087] The second element 25 is arranged radially outside with respect to the first element 24. In detail, the second element 25 includes a radially interior surface 26, which faces the first element 24 (Figures 3 and 4).

[0088] In particular, the first element 24 and the radially interior 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 A.

[0089] Since the third chamber 23 contains an incompressible fluid, any relative displacement 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 in the relative position of the second element 25 with respect to the first element 24.

[0090] Advantageously, the vehicle 1 further includes an adjustment system 9 configured to automatically adjust the stiffness k2 of the hydropneumatic suspension 8 according to one or more parameters ir of the vehicle 1, in order to modify the height h.

[0091] Indeed, as mentioned above, under the same vehicle loading conditions 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 total stiffness K and, in particular, on the equivalent stiffness keq of 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 stiffness k2.

[0092] 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 pO, which is directly proportional to the stiffness k2.

[0093] As a consequence of the variation in stiffness k2 and under the same loading conditions of vehicle 1, vehicle 1 can be moved at least between a lowered position ([Fig. 1]), in which the height h is equal to a value hl, and a position high ([Fig.2]), in which the height h is equal to a value h2, which is greater than the value hl.

[0094] The value hl is chosen so as to make the saddle 5 accessible to drivers of small stature and / or to allow the driver to place both feet on the ground G when the vehicle 1 is stationary or in a state of imminent stop.

[0095] In particular, the saddle-type vehicle 1 is stationary when its speed parallel to the direction of travel X is equal to zero. Thus, vehicle 1 is stationary when it is parked or, for example, when stopped at a red light. Conversely, the saddle-type vehicle 1 is in the condition of imminent stopping when its speed parallel to the direction of travel X is gradually reduced and is equal to or less than a speed threshold.

[0096] In the embodiment shown, the value hl is less than the value h2 of 40 mm. Furthermore, by way of example, the velocity threshold can be set at 5 m / s.

[0097] Preferably, vehicle 1 is set in the lowered position when stationary or in the state of imminent stop and unloaded, i.e. without driver or passenger riding it and without any other load being carried by it.

[0098] In addition, theoretically, vehicle 1 is set in the raised position when it moves in the direction of progression X and is unloaded.

[0099] The vehicle 1 further includes a control unit 10, which is operationally connected to the adjustment system 9. In detail, the control unit 10 is configured to receive parameters ir and to send an adjustment instruction to the adjustment system 9 based on the parameters ji, in order to adjust an equivalent stiffness keq.

[0100] 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.

[0101] One or more parameters ir provide an indication that the saddle-type vehicle 1 is stationary or is in the state of imminent stop.

[0102] The ir parameters may include the speed of the vehicle 1 parallel to the direction of travel X and / or an indication of the gear engaged.

[0103] Furthermore, the vehicle 1 includes footplates 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 ir may include an indication that the driver's feet are not placed on the footplates / footrests. This is based on the fact that at least one of the driver's feet is generally positioned on floor G and is not positioned on the footplates / footrests when vehicle 1 is stationary or is in the state of imminent stop.

[0104] The adjustment system 9 includes, in detail, an adjustment device 30, which is adapted to move within the first part 16 in order to modify the internal volume V. The adjustment system 9 further includes an automatic actuation means 31 for driving the adjustment device 30.

[0105] The adjustment device 30 is movable between a retracted position ([Fig.3]), in which the internal volume V is equal to a first value VI, and an extended position ([Fig.4]), in which the internal volume V is equal to a second value V2 less than the first value VL. In detail, the automatic actuation means 31 is configured to move the adjustment device 30 between the retracted position and the extended position.

[0106] As shown in Figures 3 and 4, the adjustment device 30 is configured to move inside the second chamber 22 and is spaced away from the first chamber 20.

[0107] As mentioned above, the fluid contained inside the second and third chambers 22, 23 being incompressible, any variation of the internal volume V causes a redistribution of the incompressible fluid inside the first part 16 and / or the second part 17.

[0108] In particular, if the internal volume V is reduced and the force FQ is greater than the threshold force F0, the separating wall 21 is adapted to slide along direction B, in order to reduce the volume of the first chamber 20 and increase the volume of the second chamber 22. As a result, the pressure p of the gas contained within the first chamber 20 is increased. Alternatively, or in addition, at least some of the incompressible fluid is transferred from the second chamber 22 to the third chamber 23.

[0109] Conversely, if the internal volume V is increased, the separating wall 21 is adapted to slide along direction B, thereby increasing the volume of the first chamber 20 and decreasing the volume of the second chamber 22. Consequently, the pressure p of the gas contained within the first chamber 20 is decreased. Alternatively, or in addition, at least some of the incompressible fluid is transferred from the third chamber 23 to the second chamber 22.

[0110] The pressure threshold pO is also variable depending on the volume of the first chamber 20. In detail, the pressure threshold pO is increased if the gas contained in the first chamber 20 is compressed, and is decreased if the gas contained in the first chamber 20 is expanded.

[0111] In particular, the pressure threshold pO is equal to a value pOl when the volume V is equal to the value VI, and to a value pO2 when the volume V is equal to the value V2.

[0112] Furthermore, since the threshold force FO depends on the pressure threshold pO and the extension of the cross-section Q is not variable, the threshold force FO, when the pressure threshold pO is equal to a value pO1, is less than the threshold force FO when the pressure threshold pO is equal to a value pO2. 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.

[0113] Furthermore, the stiffness k2 of the hydropneumatic spring 8 being directly proportional to the threshold value pO, the stiffness k2, when the pressure threshold pO is equal to the value pOl, is less than the stiffness k2 when the pressure threshold pO is equal to the value pO2.

[0114] In particular, the automatic actuation means 31 includes an electric motor 32. In the embodiment shown, the electric motor 32 is a stepper motor and the adjustment device 30 is a screw element operationally connected to the stepper motor 32. In detail, the electric motor 32 is configured to slide the adjustment device 30 parallel to the direction B between the retracted position and the extended position.

[0115] In more detail, the adjustment device 30, in the retracted position, extends over a length L1 inside the internal volume V and brings the volume V to equal the value VI ([Fig. 3]); the adjustment device 30, in the extended position, extends over a length L2 inside the internal volume V and brings the volume V to equal the value V2 ([Fig. 4]). The length L2 is greater than the length L1.

[0116] The characteristic curve of the hybrid suspension 15 when the actuation device 30 is in the retracted position is illustrated in [Fig. 5]. In detail, [Fig. 5] 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).

[0117] As is known, the equivalent stiffness keq corresponds to the slope of the characteristic curve shown in [Fig.5].

[0118] The characteristic curve of the hybrid suspension 15 shown in [Fig. 5] comprises a first section la and a second section lia. The first and second sections la, lia are linear or substantially linear and have distinct respective slopes, which correspond to two different respective values ​​of equivalent stiffness keq. In particular, an equivalent stiffness keq at the first section la is lower than an equivalent stiffness keq at the second section lia.

[0119] The first segment 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 The segment lia extends between point S and a point T, which is defined by a value xeqT of equivalent strain xeq.

[0120] In detail, the origin O is defined by a zero value of equivalent deformation xeq. However, the origin coordinate O along the vertical axis may be different from zero, for example equal to the preload of the elastic element 7.

[0121] 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.

[0122] In particular, when the equivalent strain xeq is equal to zero, the pressure p is equal to the value pOl; when the equivalent strain xeq is between zero and the value xeqS, the pressure p is greater than the value pOl and the volume of the first chamber 20 is greater than the minimum volume value; when the equivalent strain xeq is equal to the value xeqS, the volume of the first chamber 20 is equal to the minimum volume value.

[0123] When the equivalent deformation xeq is between the value xeqS and the value xeqT, the elastic element 7 works and the equivalent stiffness keq is substantially equal to the stiffness kl.

[0124] It is also possible to define a point H1 whose abscissa xeqHl corresponds to the value hl of height h and whose ordinate corresponds to the weight of the frame 2. In detail, when the equivalent deformation xeq is equal to xeqHl, the vehicle 1 is in the lowered position.

[0125] It is also possible to define a point Q, whose abscissa xeqQ corresponds to a value of height h, which is less than the value hl (i.e. 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.

[0126] The characteristic curve of the hybrid suspension 15 when the actuation device 30 is in the extended position is illustrated in [Fig. 6]. Like [Fig. 5], [Fig. 6] is a graph of the force applied to the hybrid suspension 15 as a function of its equivalent deformation xeq.

[0127] In particular, the graphs in Figures 5 and 6 share the same reference unit and scale. Therefore, corresponding points on the respective horizontal axes of Figures 5 and 6 indicate the same equivalent strain value xeq. The same applies to the respective vertical axes of Figures 5 and 6.

[0128] The characteristic curve shown in [Fig.6] includes a first segment Ib, a second segment Ilb and a third segment Illb.

[0129] The first segment 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 segment Ilb extends between the point U and a point V, which is defined by a value xeqV of equivalent strain xeq; the third segment Illb extends between point V and a point Z, which is defined by a value xeqZ of equivalent strain xeq.

[0130] 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 kl; 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 kl.

[0131] In particular, when the equivalent strain xeq is between zero and the value xeqU, the pressure p is equal to the value p02; when the equivalent strain 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 strain xeq is equal to the value xeqV, the volume of the first chamber 20 is equal to the minimum volume value.

[0132] Furthermore, the slope of the first section is less than the slope of the second section. This is due to the fact that the stiffness k2, when the actuation device 30 is in the retracted position, is less than the stiffness k2 when the actuation device 30 is in the extended position.

[0133] 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 the frame 2. In detail, when the equivalent deformation xeq is equal to xeqH2, the vehicle 1 is in the raised position.

[0134] By comparing [Fig. 5] with [Fig. 6], it is easy to see that the value xeqH2 is less than the value xeqHl. As a result, the value h2 is less than the value hl of the height h.

[0135] It is also possible to define a point J, whose abscissa xeqj corresponds to a value of height h, which is less than the value h2 (i.e. 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 progression X. Therefore, in this condition, the vehicle 1 is also loaded by a dynamic load due to the variability of the ground G.

[0136] The saddle-type vehicle 1 further includes a user interface 33, which is operationally connected to the control unit 10 (Figures 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 hl and / or h2 values.

[0137] In particular, the position of vehicle 1 can also be adjusted according to the presence of a passenger and / or loads on vehicle 1.

[0138] Furthermore, the stiffness kl, k2 can be chosen such that the value xeqj is less than the value xeqHl 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 travel X is greater than the value hl of the height h.

[0139] The operation of vehicle 1 is described from a state in which vehicle 1 is stationary and unloaded (for example, vehicle 1 is parked).

[0140] In this condition, the adjustment device 30 is in the retracted position and extends along the length L1 inside the second chamber 22 ([Fig.3]). Consequently, the height h is equal to the value hl and the vehicle 1 is in the lowered position.

[0141] In detail, this condition corresponds to point Hl of the characteristic curve shown in [Fig.5].

[0142] The value hl being chosen so as to make the saddle 5 accessible to small riders or adjusted by the rider, the rider can easily straddle the saddle 5.

[0143] After the rider has straddled the saddle 5, the suspension system 6 is loaded by the rider's weight and the equivalent deformation xeq of the hybrid suspension 15 increases.

[0144] This condition corresponds to point Q of the characteristic curve shown in [Fig. 5]. Consequently, the height h becomes less than the value hl.

[0145] When vehicle 1 starts to move forward along the direction X, the ir parameters send to the control unit 10 the indication that vehicle 1 is not stationary, nor in the state of imminent stop.

[0146] The control unit 10 instructs the adjustment device 30 to slide from the retracted position ([Fig.3]) to the extended position ([Fig.4]) based on the parameters jt. In detail, the adjustment device 30 slides parallel to the direction B and takes the length L2 inside the second chamber 22.

[0147] In the theoretical condition in which vehicle 1 is unloaded and moves along the direction of travel 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 be equal to the value h2 and vehicle 1 would be in the raised position.

[0148] However, since the vehicle 1 moving along the direction of progression 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 [Fig.6]).

[0149] In detail, when the equivalent deformation xeq is equal to xeqj, the height h is less than the value h2. However, by comparing [Fig.5] with [Fig.6], it is possible to note that the value xeqj of [Fig.6] is less than the value xeqQ of [Fig.5].

[0150] Therefore, when the vehicle 1 is loaded and moving along the direction X, the height h is greater when the adjustment device 30 is in the extended position ([Fig.6]) than when the adjustment device 30 is in the retracted position ([Fig.5]).

[0151] When vehicle 1 slows down along the direction of travel X or comes to a complete stop, ir parameters send to the control unit 10 the indication that vehicle 1 is in the state of imminent stop or is stationary.

[0152] The control unit 10 instructs the adjustment device 30 to slide from the extended position ([Fig.4]) to the retracted position ([Fig.3]) based on the parameters jt.

[0153] As a result, the internal volume V becomes equal to the value VI and the equivalent deformation xeq becomes equal to the value xeqQ, which corresponds to a height h that is less than the value hl. Therefore, the rider can place both feet on the ground G while straddling the saddle 5.

[0154] The advantages of the saddle-type vehicle 1 and of the method of controlling a saddle-type vehicle according to the invention will become apparent from the above description.

[0155] Since the vehicle 1 includes an adjustment system 9 configured to automatically adjust the stiffness k2 of the hydropneumatic spring 8, the seat height h 5 can be modified according to the driver's needs and biometric parameters. In particular, unlike the static seat height adjustment discussed in the introductory part of this description, the height h can be modified dynamically based on the parameters jt. Consequently, the height h can be adjusted without permanently altering the dynamic behavior of the suspension system 6.

[0156] Furthermore, the vehicle 1 can be moved automatically at least between the lowered and raised positions. Consequently, on the one hand, the seat 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 application range and operational requirements of the vehicle 1 when the vehicle 1 is moving along the direction of travel X.

[0157] Furthermore, since the value h2 can be chosen substantially independently of the value hl, the thickness t can be increased to improve rider comfort. Indeed, a greater thickness t corresponds to thicker padding of the saddle 5 and, consequently, to a greater capacity of the saddle 5 to absorb bumps and vibrations transmitted to the rider.

[0158] In addition, since the vehicle 1 includes a user interface 33, the height h can be modified by the driver according to the driver's needs and biometric parameters.

[0159] In addition, the height h can be precisely modified also according to the particular loading conditions of vehicle 1, for example when a passenger or loads are present on vehicle 1.

[0160] Finally, it appears that modifications and variants not outside the scope of protection of the invention can be made concerning the vehicle 1 and the method according to the present invention.

[0161] In particular, the suspension system 6 could include hybrid suspensions 15 that are different from each other. For example, the hybrid suspensions 15 mounted on the front wheel 3 could have a different stiffness k2 than the hybrid suspensions 15 mounted on the rear wheel 4.

Claims

1. Demands 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 for use as a seat by the driver and / or a passenger and which is mounted on said frame (2) at a height (h) relative 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 rigidity (K) and coupling said frame (2) with said front and rear wheels (3, 4) in a relative position variable 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 rigidity (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 operationally coupled to each other and defining said equivalent stiffness (keq); said equivalent stiffness (keq) being variable as a function of said relative position; and said hybrid suspension (15) further includes a shock absorber (11), which is adapted to dampen the oscillations of said elastic element (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:

2. - 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 within an internal volume (V) of said first part (16); said third chamber (23) being formed at the level of said second part (17); said first part (16) comprising, in turn, a separating wall (21), which hermetically separates said first chamber (20) from said second chamber (22); said separating wall (21) being able to slide or deform within said internal volume (V) so as to cause a variation of said pressure (p); said separating wall (21) being able to slide or deform according to said internal volume (V) and the volume of said incompressible fluid transferred between said second chamber (22) and said third chamber (23); and said vehicle further includes an adjustment system (9) configured to automatically adjust said second stiffness (k2) according to one or more parameters (jt) of said vehicle (1), so as to modify said height (h), said adjustment system (9) comprising: - an adjustment device (30) adapted to modify said internal volume (V) so as to cause said partition wall (21) to slide; and - an automatic actuation means (31) for driving said adjustment device (30). Saddle-type vehicle according to claim 1, characterized in that it further comprises a control unit (10) operationally connected to said adjustment system (9); said control unit (9) being configured to receive said one or more parameters (ji) and to send an adjustment instruction to said adjustment system (9) on the basis of said one or more parameters (ji) in order to adjust said second stiffness (k2).

3. Saddle-type vehicle according to claim 2, wherein said saddle-type vehicle (1) is mobile at least between a lowered position, in which said height (h) is equal to a first height value (hl), 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 (hl); characterized in that said control unit (10) is configured to send said adjustment instruction to lower said second stiffness (k2) in order to adjust said saddle-type vehicle (1) in said lowered position and to send said adjustment instruction to raise said second stiffness (k2) in order to adjust said saddle-type vehicle (1) in said raised position according to said one or more parameters (jt).

4. Saddle-type vehicle according to claim 3, characterized in that said one or more parameters (ji) are adapted to provide an indication that said saddle-type vehicle (1), in use, is stationary or is in a state of imminent stop; characterized in that said control unit (10) is configured to send said adjustment instruction to lower said second stiffness (k2) in order to set said saddle-type vehicle (1) in said lowered position when said one or more parameters (jt) provide, in use, said indication that said saddle-type vehicle (1) is stationary or is in said state of imminent stop.

5. Saddle-type vehicle according to claim 1, 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 (VI), and an extended position, in which said internal volume (V) is equal to a second value (V2); said second value (V2) being less than said first value (VI); said automatic actuation means (31) comprising an electric motor (32), which is configured to actuate said adjustment device (30) between said retracted position and said extended position.

6. A saddle-type vehicle according to claim 5, characterized in that said electric motor (32) is a stepper motor and said adjustment device (30) is a screw element operationally connected to said stepper motor (32).

7. Saddle-type vehicle according to any one of claims 2 to 6, characterized in that it comprises a user interface (33), which is operationally connected to said control unit (10); said user interface (33) being configured to receive a user instruction to change said height (h) of said saddle (5).

8. 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 travel (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) relative 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 rigidity (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 rigidity (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 (kl) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) being operationally coupled to each other and defining said equivalent stiffness (keq); said equivalent stiffness (keq) being variable as a function of said relative position; said process being characterized in that it comprises the steps of: (i) detect one or more parameters (ji) of said saddle-type vehicle (1); (ii) automatically adjust said second stiffness (k2) by means of an adjustment system (9) of said saddle-type vehicle (1) according to said one or more parameters (ji), in order to modify said height (h), and said process includes the step of: (v) vary an internal volume (V) of a first part (16) of said hydropneumatic spring (8) by means of an adjustment device (30) of said adjustment system (9), which is driven by an automatic actuation means (31) of said adjustment system (9); said hybrid suspension (15) further comprising a shock absorber (11), which is adapted to dampen the oscillations of said elastic element (7) and / or said hydropneumatic spring (8); said hydropneumatic spring (8) comprising said 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 to each other and contain an incompressible fluid; said first chamber (20) and said second chamber (22) being formed within an internal volume (V) of said first part (16); said third chamber (23) being formed at the level of said second part (17); said first part (16) comprising, in turn, a separating wall (21), which hermetically separates said first chamber (20) from said second chamber (22); said separating wall (21) being able to slide or deform within said internal volume (V) so as to cause a variation of said pressure (p); said separating wall (21) being able to slide or deform according to said internal volume (V) and the volume of said incompressible fluid transferred between said second chamber (22) and said third chamber (23).

9. Control method according to claim 8, characterized in that it further comprises the step of: iii) sending 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 at least one of the continuous positions between a lowered position and a raised position of said saddle-type vehicle (1); said lowered position corresponding to a first height value (hl) 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 (hl).

10. Control method according to claim 9, characterized in that it further comprises the step of: iv) sending said adjustment system (9) said adjustment instruction through said control unit (10) to adjust said saddle-type vehicle (1) in said lowered position when said one or more parameters (jt) provide an indication that said saddle-type vehicle (1) is stationary or is in a state of imminent stop.

11. Control method according to claim 8, characterized in that it comprises the additional step of: vi) moving said adjustment device (30) between a retracted position and an extended position by means of an electric motor (32) of said automatic actuation means (9); said retracted position corresponding to a first value (VI) 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 less than said first value (VI).

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