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

Abstract

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

Description

Title of the invention: SADDLE-TYPE VEHICLE, SUSPENSION KIT FOR A SADDLE-TYPE VEHICLE, AND METHOD FOR UPDATING A SADDLE-TYPE VEHICLE

[0001] TECHNICAL DOMAIN The present invention relates to a saddle-type vehicle comprising an improved suspension system, a suspension kit for a saddle-type vehicle and a method for upgrading a saddle-type vehicle.

[0002] TECHNOLOGICAL BACKGROUND Saddle-type vehicles are known, including: - 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 motor, which is adapted to provide traction torque to a front and / or rear wheel.

[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 are also known to have two front or rear wheels, which are mounted so as to be inclined relative to the frame.

[0005] Saddle-type vehicles can be configured in different ways, for example in the form of motorcycles, scooters or mopeds.

[0006] Saddle-type vehicles further include a suspension system, which couples the frame to the wheels in a variable relative position of one with respect to the other.

[0007] The suspension system contributes to the handling and braking of the vehicle. In addition, it provides safety and comfort by keeping the driver isolated from road noise, bumps and vibrations.

[0008] The suspension system includes, more specifically, a front suspension part and a rear suspension part, which respectively connect the front and rear wheels to the frame.

[0009] Generally, the front suspension part includes one or two fork tubes and the rear suspension part includes a swing arm with one or two suspensions.

[0010] Furthermore, the mass of a saddle-type vehicle can be divided into sprung mass and unsprung mass. Specifically, the sprung mass comprises the portion of the vehicle's mass that is supported by the suspension system. Complementarily, the unsprung mass comprises the portion of the vehicle's mass that is not supported by the suspension system.

[0011] The frame of saddle-type vehicles, for example, forms part of the sprung mass and the rear and front wheels form part of the unsprung mass.

[0012] As a general rule, it is preferable to keep the unsprung mass of the vehicle as low as possible relative to the sprung mass of the vehicle. One reason for this is that the lower the unsprung mass, the less the suspension system has to work to keep the wheels – which are part of the unsprung mass – in contact with the ground.

[0013] A first category of saddle-type vehicles is known, in which the engine is part of the vehicle's sprung mass. For example, off-road motorcycles belong to this first category.

[0014] A second category of saddle-type vehicles is also known, in which the engine is at least partially part of the vehicle's unsprung mass. For example, most scooters and mopeds belong to this second category. In practice, the scooter engine is generally mounted on the rear suspension, and in particular on the swingarm.

[0015] In light of the above, for the same total vehicle mass, the suspension system of second-category saddle-type vehicles is less efficient than the suspension system of first-category saddle-type vehicles. In fact, for the same total vehicle mass, since the engine is part of the unsprung mass, the unsprung mass of second-category saddle-type vehicles is greater than the unsprung mass of first-category saddle-type vehicles.

[0016] From a practical point of view, this means that the suspension system of second category saddle-type vehicles transmits the majority of road vibrations and irregularities to the driver.

[0017] Consequently, there is a need in the industry to increase the efficiency of the suspension system of saddle-type vehicles in which the engine is included at least partly in the unsprung mass of the vehicle.

[0018] DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a saddle-type vehicle, enabling at least one of the above-mentioned needs to be met in a simple and economical manner.

[0019] This objective is achieved by a saddle-type vehicle comprising a frame, a front wheel that can be steered relative to said frame and can rotate about its own first axis, a rear wheel connected to said frame in such a way as to be able to rotate about its own second axis, a suspension system coupling said frame with said front and rear wheels in a relative position of one with respect to the other that varies along a direction perpendicular to the ground, and an engine adapted to provide said front and / or rear wheel with traction torque. Said saddle-type vehicle has a total mass and comprises a suspended mass portion having a first mass and an unsprung mass portion having a second mass. Said total mass is equal to the sum of said first mass and said second mass.The suspension system is interposed between the suspended mass and the unsprung mass, so as to support the suspended mass relative to the unsprung mass. The unsprung mass rests on the ground during operation. The unsprung mass includes at least a portion of the engine.

[0020] The saddle-type vehicle is characterized in that said suspension system comprises at least one hybrid mechanical hydropneumatic suspension, said hybrid suspension in turn comprising at least one elastic 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 an equivalent rigidity of said hybrid suspension, said equivalent rigidity being variable according to said relative position.

[0021] In one embodiment, the suspension system may include a front suspension part and a rear suspension part, which couple said frame respectively with said front wheel and said rear wheel, and may further be characterized in that said rear suspension part includes said at least one hybrid suspension.

[0022] In one embodiment, said suspension system may include an adjustment system for adjusting said second stiffness of said hydropneumatic spring of said at least one hybrid suspension, so as to vary said equivalent stiffness of said at least one hybrid suspension.

[0023] In one embodiment, the rear wheel may define a median plane perpendicular to said second axis, said median plane in turn defining two opposite sides of said rear wheel, and the saddle-type vehicle may further be characterized in that said rear suspension part comprises two hybrid suspensions, which are arranged on the respective opposite sides of said rear wheel.

[0024] In one embodiment, said adjustment system can be adapted to adjust the second stiffness of the respective hydropneumatic springs of the two hybrid suspensions included in said rear suspension part.

[0025] In one embodiment, said suspension system may further comprise at least one shock absorber, which is adapted to dampen the oscillations of said elastic element and / or said hydropneumatic spring of said at least one hybrid suspension, said hydropneumatic spring of said at least one hybrid suspension comprising a first part, which is spaced from said shock absorber, and a second part, which is mounted coaxially on said shock absorber. Said first part may, in turn, comprise: - a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second rigidity, and - a second chamber and a third chamber, which are in fluidic communication with each other and contain an incompressible fluid.

[0026] Said first chamber and said second chamber may be formed within an internal volume of said first part, said third chamber being formed at the level of said second part. Said first part may, in turn, comprise a separating wall, which hermetically seals 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 may be sliding or deformable depending on said internal volume and the volume of said incompressible fluid transferred between said second chamber and said third chamber.

[0027] In this embodiment, the saddle-type vehicle can further be characterized in that said adjustment system comprises an adjustment device which is in fluidic communication with said second chamber and / or with said third chamber via one or more conduits, said conduits and the volume of said second chamber and / or said third chamber defining a volume, said adjustment device being adapted to vary said volume so as to cause the sliding of said separating wall and the variation of said second stiffness.

[0028] In one embodiment, said adjustment device may be in fluidic communication with said respective second and / or third chambers of said two hybrid suspensions included in said rear suspension part, said adjustment device being adapted to vary said volume so as to cause the sliding of the respective separation walls and variation of the second respective rigidity of said two hybrid suspensions.

[0029] In one embodiment, said saddle-type vehicle may be a scooter or a moped.

[0030] The object of the invention is also achieved by a suspension kit 100 for a saddle vehicle. The suspension kit for a saddle-type vehicle comprises at least two hybrid mechanical hydropneumatic suspensions, each of said hybrid suspensions 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 of each hybrid suspension are functionally coupled to each other and define a variable equivalent stiffness of the respective hybrid suspension.

[0031] The suspension kit for a saddle-type vehicle further includes an adjustment system for adjusting the second stiffness of the respective hydropneumatic springs of the hybrid suspensions, so as to vary the equivalent stiffness of the respective hybrid suspensions. The mechanical hydropneumatic hybrid suspensions are adapted to be interposed between a portion of the sprung mass and a portion of the unsprung mass of the vehicle, which respectively have a first mass and a second mass. The sum of the first mass and the second mass is equal to the total mass of the vehicle. The unsprung mass rests on the ground during use.

[0032] In one embodiment of the kit, each hydropneumatic spring may comprise a first part, which is adapted to be spaced from a respective shock absorber of said saddle-type vehicle, and a second part, which is adapted to be mounted coaxially on said shock absorber, said first part comprising, in turn: - a first chamber, which contains a gas at a pressure, said pressure being directly proportional to said second rigidity; and - a second chamber and a third chamber, which are in fluidic communication with each other and contain an incompressible fluid.

[0033] Said first chamber and said second chamber may be formed within an internal volume of said first part, said third chamber being formed at the level of said second part. Said first part may, in turn, comprise a separating wall, which hermetically seals said first chamber from said second chamber. Said separating wall may be sliding or deformable within said internal volume so as to cause a variation of said pressure. Said separating wall may be sliding or deformable depending on said internal volume and the volume of said incompressible fluid transferred between said second chamber and said third chamber.

[0034] The kit can be characterized in that said adjustment system comprises an adjustment device which is in fluidic communication with respective second and / or third chambers of said two hybrid suspensions by means of one or more conduits, said conduits and the volume of said second and / or third chambers defining a volume, and said adjustment device being adapted to vary said volume so as to cause the sliding of respective separating walls and the variation of the respective second stiffness of said two hybrid suspensions.

[0035] The object of the invention is further achieved by a method for updating a saddle-type vehicle comprising, in turn: - a frame; - a front wheel, which can be steered relative to the frame and which can rotate around its own first axis; - a rear wheel, which is connected to the frame in such a way that it can rotate around its own second axis; - a suspension system coupling said frame to said front and rear wheels in a relative position of one with respect to the other, varying along a direction perpendicular to the ground; and - a motor adapted to provide said front and / or rear wheel with traction torque;

[0036] said method being characterized in that it comprises the steps of: (i) to have at least one mechanical hydropneumatic hybrid suspension between a portion of the sprung mass and a portion of the unsprung mass of said vehicle, which respectively have a first mass and a second mass, the sum of said first mass and said second mass being equal to a total mass of said vehicle, said portion of the unsprung mass resting, in use, on the ground, said at least one hybrid suspension comprising at least one elastic element having a first stiffness and at least one hydropneumatic spring having a second stiffness, said elastic element and said hydropneumatic spring of each hybrid suspension being operationally coupled to each other and defining an equivalent stiffness of said hybrid suspension, which is variable according to said relative position, and ii) fluidly connect said at least one hydropneumatic mechanical hybrid suspension to an adjustment system to adjust said second stiffness, so as to vary said equivalent stiffness.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: - [Fig.1] is a side view of a saddle-type vehicle according to the present invention; - [Fig.2] is a diagram of part of a suspension system of the saddle-type vehicle of [Fig.1], with parts being removed for clarity; - [Fig.3] illustrates the respective steps of a process for updating the saddle-type vehicle of [Fig.1]; - [Fig.4] illustrates the respective steps of a process for updating the saddle-type vehicle of [Fig.1]; - Figure 5 illustrates the respective steps of a process for updating the saddle-type vehicle shown in Figure 1; and - [Fig.6] is a graph illustrating the characteristic curves of a suspension of the suspension system of [Fig.2] under different respective adjustment conditions.

[0038] BEST WAY OF IMPLEMENTING THE INVENTION Referring to [Fig.1], the numerical reference 1 indicates a saddle-type vehicle.

[0039] In the embodiment shown, the saddle-type vehicle is a scooter. Alternatively, the saddle-type vehicle is a moped.

[0040] In the remainder of this description, expressions such as "front", "rear", and similar are used with reference to a normal direction of progression and a normal operational position of the vehicle 1 shown in the attached figures.

[0041] As shown in [Fig. 1], vehicle 1 essentially comprises: - a frame 2; - a front wheel 3, which can be steered relative to the frame 2 and which can rotate around its own axis A; - a rear wheel 4, which is connected to the frame 2 in such a way as to be able to rotate around its own axis B; - a motor 5 adapted to provide traction torque to the front and / or rear wheels 3, 4; and - a suspension system 6 coupling the frame 2 to the front and rear wheels 3, 4 in a relative position of one with respect to the others variable along a direction Z perpendicular to the ground G.

[0042] 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.

[0043] In particular, vehicle 1 has a total mass M. This means that the sum of the mass of all the components forming vehicle 1 is equal to the total mass M.

[0044] Furthermore, the vehicle 1 comprises a sprung mass portion S having a mass s and an unsprung mass portion U having a mass u. In detail, the sprung mass portion S includes all the components of the vehicle 1 that are supported by the suspension system 6; conversely, the unsprung mass portion U includes all the components of the vehicle 1 that are not supported by the suspension system 6. The sum of the mass s and the mass u is equal to the total mass M.

[0045] In other words, the suspension system 6 is interposed between the suspended mass part S and the unsprung mass part U to support the suspended mass part S relative to the unsprung mass part U. In addition, the unsprung mass part U is adapted to rest, in use, on the ground G.

[0046] In addition, certain components of vehicle 1 may belong partly to the suspended mass part S and partly to the unsprung mass part U.

[0047] In detail, the engine 5 belongs at least in part to the unsprung mass portion U. In other words, the mass of the engine 5 contributes to the mass u of the unsprung mass portion U. Therefore, at least part of the mass of the engine 5 is not supported by the suspension system 6.

[0048] In addition, the suspension system 6 includes a front suspension part 6a and a rear suspension part 6b, which couple the front and rear wheels 3, 4 respectively to the frame 2.

[0049] The front and rear suspension parts 6a, 6b are loaded by respective loads which depend on the mass s, the mass of the driver and any passengers and the mass of any goods transported on the vehicle 1. The loads acting on the front and rear suspension parts 6a, 6b also depend on the loads exerted respectively on the front and rear wheels 3, 4 by the ground G.

[0050] Generally, when the vehicle 1 is stationary or in a state of average progress, the load acting on the rear suspension part 6b is greater than the load acting on the front suspension part 6a.

[0051] In detail, vehicle 1 is at rest when its ground speed G is zero. Furthermore, vehicle 1 is in a state of average movement when it is moving on a sufficiently smooth and not steep road, for example, a road in an urban area, at a speed consistent with the speed limits of the urban area. For example, vehicle 1 is not in a state of average movement when it is moving on a bumpy surface and / or an uphill road.

[0052] For example, when the vehicle 1 is unloaded, that is, without a driver or passenger riding on it and without any other load being carried by it, the ratio between the load acting on the front suspension part 6a and the load acting on the rear suspension part 6b is equal to 1:4. Moreover, when the vehicle 1 is loaded, for example by the weight of the driver, the ratio between the load acting on the front suspension part 6a and the load acting on the rear suspension part 6b may be even less than 1:4.

[0053] In the embodiment shown in [Fig.1], a motor 5 is mounted on the rear suspension part 6b.

[0054] The rear suspension part 6b includes, in detail, a swing arm 50, which is adapted to fix the rear wheel 4 to the frame 2. In more detail, the engine 5 is fixed to the swing arm 50.

[0055] In the embodiment shown, the swing arm 50 is a double-sided swing arm, that is to say, it comprises two arms surrounding the respective sides of the rear wheel 4 with respect to a median plane P defined by the rear wheel 4 and perpendicular to the axis B.

[0056] Advantageously, the suspension system 6 includes at least one hydropneumatic mechanical hybrid suspension 15.

[0057] Such a hybrid suspension 15 is known for example from WO-Al-2015155712 and IT-A1-102012902090112 and is marketed by the company Umbria Kinetics under the name AirTender®.

[0058] In the embodiment shown, the suspension system 6 comprises two hybrid suspensions 15 at the level of the rear suspension part 6b.

[0059] In detail, the two hybrid suspensions 15 are arranged on either side of the rear wheel 4 with respect to plane P. In more detail, the two hybrid suspensions 15 are constrained at least indirectly between the swing arm 50 and the frame 2. This means that the hybrid suspensions 15 could be constrained with respect to the swing arm 50 by means of an intermediate component, such as a lever.

[0060] The following description will be made with reference to a single hybrid suspension 15 mounted on the rear wheel 4, all the hybrid suspensions 15 being identical to each other.

[0061] The hybrid suspension 15 comprises, in detail, an elastic element 7 having a stiffness kl and a hydropneumatic spring 8 having a stiffness k2 ([Fig.2]). In detail, the stiffness k2 is less than the stiffness kl.

[0062] Preferably, the rear suspension part 6b comprises two shock absorbers 11, which are respectively arranged on both sides of the rear wheel 4 with respect to plane P.

[0063] In detail, the hybrid suspension 15 is adapted to interact with one of the two shock absorbers 11 of the suspension system 6, which is constrained between the rear wheel 4 and the frame 2 and defines an axis C. The shock absorber 11 is adapted to dampen the oscillations of the elastic element 7 and / or 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, which is 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 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.

[0066] 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.

[0067] The equivalent stiffness keq is variable depending on the relative position between the frame 2 and the wheels 3, 4. In detail, the equivalent stiffness keq can be different for different values ​​of the equivalent deformation xeq.

[0068] 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 ([Fig. 2]).

[0069] In detail, the elastic element 7 is adapted to cooperate with the shock absorber 11. In more detail, the elastic element 7 is able to compress or expand along the axis C depending on the sliding of the slider of the shock absorber 11 inside the respective cylinder.

[0070] Furthermore, as illustrated in Figures 2 and 5, each hydropneumatic spring 8 comprises a first part 16 and a second part 17. Preferably, the first part 16 is spaced away from the shock absorber 11 and the second part 17 is mounted coaxially on the shock absorber 11 ([Fig.2]).

[0071] In addition, the hydropneumatic spring 8 comprises: - a first chamber 20, which contains a gas at a pressure p; - a second chamber 22 and a third chamber 23, which are in fluidic communication with each other and contain an incompressible fluid.

[0072] 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.

[0073] As illustrated in Figures 2 and 5, the first and second chambers 20, 22 are formed inside an internal volume V of the first part 16 and the third chamber 23 is formed inside the second part 17.

[0074] The first part 16 comprises, in turn, a separating wall 21, which hermetically separates the first chamber 20 from the second chamber 22 and which is sliding or deformable inside the internal volume V along a direction D. Preferably, but not necessarily, the direction D is parallel to the axis C (figures 2 and 5).

[0075] As illustrated in Figures 2 and 5, the separating wall 21 is a piston having a cross-section Q perpendicular to the direction D. Alternatively, the separating wall 21 can be a deformable membrane.

[0076] 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 partition wall 21 along direction D 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.

[0077] In general, the separating wall 21 is sliding as a function of the pressure p of the gas contained inside the first chamber 20 and as a function of the volume of incompressible fluid transferred between the second chamber 22 and the third chamber 23.

[0078] 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.

[0079] 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.

[0080] 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 decreased if the gas contained in the first chamber 20 is expanded.

[0081] As shown in Figures 2 and 5, the second part 17 of the hybrid suspension 15 comprises: - a first element 24, which is mounted as a single unit and coaxially with respect to the shock absorber 11; and - a second element 25, which is adapted to cooperate with the elastic element 7 and is mounted coaxially with respect to the shock absorber 11 in a movable manner with respect to the first element 24.

[0082] The second element 25 is arranged radially outside with respect to the first element 24. In detail, the second element 25 has a radially interior surface 26, which faces the first element 24 (Figures 2 and 5).

[0083] 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 C.

[0084] Since the third chamber 23 contains an incompressible fluid, any relative displacement between the first element 24 and the second element 25 causes the transfer of the incompressible fluid between the second chamber 22 and the third chamber 23. Similarly, any variation in the 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.

[0085] A plurality of characteristic curves of the hybrid suspension 15 are illustrated in [Fig. 6]. In detail, [Fig. 6] is a graph of the force applied to the hybrid suspension 15 as a function of its equivalent deformation xeq. Furthermore, the equivalent stiffness keq corresponds to the slope of the characteristic curves shown in [Fig. 6]. Therefore, a point on the characteristic curves defines a particular operating condition of the hybrid suspension 15.

[0086] In addition, each of the characteristic curves shown in [Fig.6] corresponds to a specific value of the threshold pressure pO.

[0087] The characteristic curve shown in continuous line on [Fig.6] comprises a section I, a section II and a section III and will be referred to hereafter as the “first characteristic curve”.

[0088] In the embodiment shown, the first characteristic curve corresponds to an adjustment condition of the hybrid suspension 15 determined by the factory settings of the hybrid suspension 15.

[0089] Section I extends between the origin O of the reference system and a point L, which is defined by a value xeqL of equivalent strain xeq; section II extends between the point L and a point J, which is defined by a value xeqj of equivalent strain xeq; section III extends between the point J and a point K, which is defined by a value xeqK of equivalent strain xeq.

[0090] When the operating point of the hybrid suspension 15 belongs to the first characteristic curve and the equivalent deformation xeq is between zero and the value xeqL, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness kl; when the equivalent deformation xeq is between the value xeqL and the value xeqj, the hydropneumatic spring 8 operates and the equivalent stiffness keq is substantially equal to the stiffness k2; when the equivalent deformation xeq is between the value xeqj and the value xeqK, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness kl.

[0091] Furthermore, the slope of section I is higher than the slope of section II. This is due to the fact that the stiffness k2 is less than the stiffness kl.

[0092] Fig. 6 illustrates two additional characteristic curves, which correspond to two different respective values ​​of the threshold pressure pO and, consequently, to two additional adjustment configurations of the hybrid suspension 15, as will be described in more detail below.

[0093] Indeed, the suspension system 6 further includes an adjustment system 9 adapted to allow variation of the stiffness k2 of the hydropneumatic spring 8, in order to vary the equivalent stiffness keq.

[0094] In detail, the adjustment system 9 is adapted to allow variation of the stiffness k2 of the hydropneumatic springs 8 of one or more hybrid suspensions 15 of the suspension system 6.

[0095] In particular, the two suspensions 15 or more and the adjustment system 9 define a suspension kit 100 for the vehicle 1.

[0096] In the embodiment shown, the adjustment system 9 controls the stiffness k2 of the two hybrid suspensions 15 of the rear suspension part 6b ([Fig.2]).

[0097] The adjustment system 9 is adapted to adjust the stiffness k2 of one or more hybrid suspensions 15 by causing a variation in the volume of the respective first chambers 20. In fact, as described previously, a variation in the volume of the first chamber 20 corresponds to a variation in the threshold pressure pO, which is directly proportional to the stiffness k2.

[0098] In particular, as illustrated in Figures 2 and 5, the adjustment system 9 includes an adjustment device 30, which is in fluidic communication with the second and / or third chambers 22, 23 of the two hybrid suspensions 15 of the rear suspension part 6b by means of one or more conduits 31.

[0099] The conduits 31 define an internal volume containing the same incompressible fluid as the second and third chambers 22, 23 of the two hybrid suspensions 15.

[0100] In the embodiment shown, the conduits 31 comprise: - a conduit 32, which fluidly connects the two suspensions 15 to each other; and - a conduit 33, comprising a first end 33a and a second end 33b, which are opposite each other.

[0101] The conduit 33 is fluidically connected to the conduit 32 at the first end 33a, and the adjustment device 30 is arranged at the second end 33b.

[0102] Preferably, the adjustment device 30 is spaced from the two suspensions 15.

[0103] In particular, the sum of the volumes of the second and third chambers 22, 23 of the respective suspensions 15 and the internal volume of the conduits 31 defines a total volume W.

[0104] The adjustment device 30 is adapted to adjust the stiffness k2 of the two suspensions 15 by varying the total volume W.

[0105] In detail, the adjustment device 30 can be slid inside the conduit 33 between a retracted position, in which the volume W is equal to a first value Wl, and an extended position, in which the volume W is equal to a second value W2 less than the first value Wl. The adjustment device 30 can further slide to any of the continuous positions between the retracted and extended positions. In particular, the adjustment device 30 can be slid manually or automatically.

[0106] As mentioned above, since the fluid contained within the second and third chambers 22, 23 and the conduits 31 is incompressible, any variation in the volume W can cause the respective separating walls 21 of the hybrid suspensions 15 to slide within the respective internal volumes V.

[0107] In particular, if the force FQ is greater than the threshold force F0, each separating wall 21 is adapted to slide along the direction D, in order to reduce the volume of the respective first chamber 20. As a result, the pressure p of the gas contained in each first chamber 20 is increased. Alternatively, or in addition, at least a portion of the incompressible fluid is transferred between each respective second chamber 22 and third chamber 23.

[0108] Conversely, if the volume W is increased, each partition wall 21 is adapted to slide along the direction D, in order to increase the volume of the respective first chamber 20. As a result, the pressure p of the gas contained in each first chamber 20 is increased. Alternatively, or in addition, at least a portion of the incompressible fluid is transferred between each respective second chamber 22 and third chamber 23.

[0109] In particular, the pressure threshold pO is equal to a value pOl when the volume W is equal to the value Wl, and to a value pO2 when the volume W is equal to the value W2. Furthermore, since the stiffness k2 of the hydropneumatic spring 8 is 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.

[0110] As mentioned above, [Fig.6] further illustrates a line in dashes interrupted by a dot and a dotted line.

[0111] In particular, the dashed line corresponds to an adjustment condition of the hybrid suspension 15 in which the pressure threshold pO is greater than the pressure threshold pO corresponding to the first characteristic curve and the pressure threshold pO corresponding to the dashed line. By way of example, the pressure threshold pO corresponding to the dashed line is equal to the value pO2, and the pressure threshold pO corresponding to the dashed line is equal to the value pO1.

[0112] In detail, the dotted line is arranged above section II and includes a section I' and a section II'.

[0113] In more detail, the section I' extends between the point L and a point R, which is defined by a value xeqR of equivalent strain xeq which is greater than the value xeqL; the section II' extends between the point R and a point Q, which is defined by a value xeqQ of equivalent strain xeqQ.

[0114] Section I' has the same slope as section I and joins section I at point L. In other words, section I' is the extension of section I.

[0115] Section II' joins section III at point Q and has a steeper slope than section IL

[0116] It is therefore possible to define a second characteristic curve of the hybrid suspension 15, which is composed successively of: section I, section I', section II' and section III between point Q and point K.

[0117] In particular, when the operating point of the hybrid suspension 15 lies within the second characteristic curve and the equivalent deformation xeq is between zero and the value xeqR, the elastic element 7 is functioning and the equivalent stiffness keq is substantially equal to the stiffness kl; when the equivalent deformation xeq is between the value xeqR and the value xeqQ, the hydropneumatic spring 8 is functioning and the equivalent stiffness keq is substantially equal to the stiffness k2; when the equivalent deformation xeq is between the value xeqQ and the value xeqK, the elastic element 7 is functioning and the equivalent stiffness keq is substantially equal to the stiffness kl. In detail, as described above, the stiffness k2, when the operating point of the hybrid suspension 15 lies within the second characteristic curve (section II'), is greater than the stiffness k2 when the operating point of the hybrid suspension 15 belongs to the first characteristic curve (section II).

[0118] In addition, the dotted line is arranged below section II and includes a section II” and a section III” ([Fig.6]).

[0119] In detail, section II” extends between a point N and a point T, which are respectively defined by values ​​xeqN and xeqT of the equivalent strain xeq; section III” extends between point T and point J. In detail, the value xeqN is less than the value xeqL.

[0120] Section II'' has a lower slope than section II and joins section I at point N. Section III'' joins section III at point J, and has the same slope as section III. In other words, section III'' is the continuation of section III.

[0121] It is therefore possible to define a third characteristic curve of the hybrid suspension 15, which consists successively of: section I between point O and point N, section II”, section III” and section III.

[0122] In particular, when the operating point of the hybrid suspension 15 belongs to the third characteristic curve and the equivalent deformation xeq is between zero and the value xeqN, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness kl; when the equivalent deformation xeq is between the value xeqN and the value xeqT, the hydropneumatic spring 8 operates and the equivalent stiffness keq is substantially equal to the stiffness k2; when the equivalent deformation xeq is between the value xeqT and the value xeqK, the elastic element 7 operates and the equivalent stiffness keq is substantially equal to the stiffness kl.In detail, as described above, the stiffness k2, when the operating point of the hybrid suspension 15 belongs to the third characteristic curve (section II'), is greater than the stiffness k2 when the operating point of the hybrid suspension 15 belongs to the first characteristic curve (section II).

[0123] In particular, when the vehicle 1 is in the state of average progression, the load acting on the hybrid suspension 15 is equal to a value Av ([Fig.6]).

[0124] The value Av corresponds to three possible operating points of the hybrid suspension 15 which belong respectively to the first, second and third characteristic curves, according to the value of the pressure threshold pO. These three points belong respectively to section II of the first characteristic curve, to section I' of the second characteristic curve and to section II'' of the third characteristic curve.

[0125] The operation of the saddle-type vehicle 1 is described starting from a state in which the hybrid suspensions 15 of the rear suspension part 6b are set based on their respective factory settings and, consequently, their respective operating points belong to the first characteristic curve. In particular, vehicle 1 is in the medium progression state and, therefore, the respective operating points of the hybrid suspensions 15 belong to section II ([Fig.6]).

[0126] As a result, the equivalent stiffness keq is substantially equal to the stiffness k2 as in section II. As a result, the suspension system 6 reacts less rigidly to the loads acting on the hybrid suspensions 15 than when the equivalent stiffness keq is substantially equal to the stiffness kl.

[0127] If the vehicle 1 is expected to be subjected to a much higher load than the value Av (for example due to the presence of a passenger), the adjustment device 30 can advantageously be slid in the conduit 33 to the extended position, in which the volume W is equal to the second value W2.

[0128] As a result, the volume of the first chambers 20 of the two hybrid suspensions 15 is compressed and the threshold pressure pO becomes equal to the value p02. Consequently, the stiffness keq is substantially equal to the stiffness k2 (comparison of section II' on [Fig.6]) also when the hybrid suspensions 15 are loaded by a load that is substantially greater than the load Av.

[0129] If, on the contrary, the vehicle 1 is expected to be subjected to a load less than the value Av, the adjustment device 30 can advantageously be slid inside the conduit 33 towards the retracted position, in which the volume W is equal to the first value Wl.

[0130] As a result, the volume of the first chambers 20 of the hybrid suspensions 15 is compressed and the threshold pressure pO becomes equal to the value pOl. Consequently, the stiffness keq is substantially equal to the stiffness k2 (comparison of section II' in [Fig.6]) even when the hybrid suspensions 15 are loaded by a load that is substantially less than the load Av.

[0131] The described solution can also be easily adapted (with a so-called "catch-up" or "update" operation) to existing saddle-type vehicles in which the engine 5 belongs at least in part to the unsprung mass part U, by: removing the existing spring coils, where appropriate, arranged coaxially with respect to the shock absorbers 11 (Figures 3 and 4); arranging one or more suspensions 15 between the sprung mass part S and the unsprung mass part U of the existing vehicle; and fluidly connecting the one or more hybrid suspensions 15 to the adjustment system 9 in order to adjust the second stiffness k2 of one or more respective hybrid suspensions 15, so as to vary the equivalent stiffness keq ([Fig.5]).

[0132] The advantages of vehicle 1 and kit 100 will become clear from the description above.

[0133] In particular, the suspension system 6 includes at least one hybrid suspension 15 having an equivalent stiffness keq, which is variable depending on the relative position between the frame 2 and the wheels 3, 4. Thus, the vehicle 1, which belongs to the second category of saddle-type vehicles described in the introductory part of this description, includes a suspension system 6 that is significantly more efficient than the suspension system of known vehicles belonging to the second category.

[0134] Indeed, since the equivalent rigidity keq is variable depending on the relative position between the frame 2 and the wheels 3, 4, the suspension system 6 can be adjusted to reduce vibrations and road irregularities transmitted to the driver.

[0135] Such an improvement in the efficiency of the suspension system 6 counterbalances the fact that the mass u of the unsprung mass part U relative to the mass s of the sprung mass part S is greater for vehicle 1 than for vehicles of the first category, because the engine 5 belongs at least in part to the unsprung mass part U.

[0136] Furthermore, since the suspension system 6 includes an adjustment system 9 for adjusting the stiffness k2, the dynamic behavior of the vehicle 1 can be adjusted according to the driver's needs or road conditions. In particular, the dynamic behavior of the vehicle 1 can be adjusted according to the presence of a passenger or additional loads on the vehicle.

[0137] Indeed, if the vehicle 1 is intended to be used under average progress conditions, it is advantageous to set the hybrid suspensions 15 to their respective factory settings (in this way, the equivalent stiffness keq is substantially equal to the stiffness k2 when the hybrid suspensions 15 are loaded by the Av load).

[0138] However, if the vehicle 1 is expected to be loaded with a much higher load than the Av value, it is advantageous to slide the adjustment device 30 so as to set the threshold pressure pO equal to the pressure value pO2. Consequently, the stiffness keq is substantially equal to the stiffness k2 even when the hybrid suspensions 15 are loaded with respective loads much higher than the Av load. In this way, the vibrations and road irregularities transmitted to the driver can be advantageously reduced even when the vehicle 1 is subjected to severe loading conditions.

[0139] Furthermore, since the rear suspension section 6b comprises two hybrid suspensions 15, the efficiency of the suspension system 6 is further improved. Indeed, as described above, the load acting on the rear suspension section 6b is generally greater than the load acting on the front suspension section 6a.

[0140] Furthermore, since the suspension system 6 includes a unique adjustment system 9 for the two hybrid suspensions 15 of the rear suspension part 6b, the equivalent stiffness keq can be adjusted without affecting the vehicle arrangement 1.

[0141] Finally, it appears that modifications and variants not falling outside the scope of protection of the claims can be made concerning the vehicle 1 and the kit 100 according to the present invention.

[0142] In particular, the swing arm 50 can be a unilateral swing arm, comprising a single arm disposed on one side of the rear wheel 4 with respect to the median plane P. Consequently, the suspension system 6 would comprise only a single hybrid suspension 15 arranged on the same side of the rear wheel 4 as that on which the single arm of the swing arm 50 is disposed.

[0143] On the other hand, the suspension system 6 may include hybrid suspensions 15 at both the rear and front suspension sections 6a, 6b. In detail, the suspension system 6 may include two or more hybrid suspensions 15 at the front suspension section 6a.

[0144] Consequently, the suspension system 6 may include an adjustment system 9 adapted to control the stiffness k2 of the hybrid suspensions 15 belonging to the front suspension part 6a and an adjustment system 9 adapted to control the stiffness k2 of the hybrid suspensions 15 belonging to the rear suspension part 6b. Alternatively, the suspension system 6 may include only one adjustment system 9 adapted to control the stiffness k2 of the hybrid suspensions 15 belonging to both the front and rear suspension parts 6a, 6b.

Claims

Demands

1. Saddle-type vehicle (1) comprising: - a frame (2); - a front wheel (3), which can be steered relative to said frame (2) and can rotate around its own first axis (A); - a rear wheel (4), which is connected to said frame (2) so as to be able to rotate around its own second axis (B); - a suspension system (6) coupling said frame (2) to said front and rear wheels (3, 4) in a relative position of one with respect to the other, variable along a direction (Z) perpendicular to the ground (G); and - a motor (5) adapted to provide said front and / or rear wheel (3, 4) with traction torque; - said saddle-type vehicle (1) having a total mass (M) and comprising a suspended mass part (S) having a first mass (s) and an unsprung mass part (U) having a second mass (U); said total mass (M) being equal to the sum of said first mass (s) and said second mass (u); said suspension system (6) being interposed between said suspended mass part (S) and said unsprung mass part (U), so as to support said suspended mass part (S) relative to said unsprung mass part (U); said unsprung mass part (U) resting, in use, on the ground (G); - said unsprung mass part (U) comprising at least a part of said engine (5); - characterized in that said suspension system (6) comprises at least two hybrid mechanical hydropneumatic suspensions (15); - each of said hybrid suspensions (15) comprising, in turn, at least one elastic element (7) having a first stiffness (k1) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) being operationally coupled to each other and defining an equivalent stiffness (keq) of said respective hybrid suspension (15); said equivalent stiffness (keq) being variable according to said relative position; and - an adjustment system (9) for adjusting said second stiffness (k2) of said respective hydropneumatic springs (8) of said hybrid suspensions (15), so as to vary said equivalent stiffness (keq) of said respective hybrid suspensions (15).

2. Saddle-type vehicle according to claim 1, wherein said suspension system (6) comprises a front suspension part (6a) and a rear suspension part (6b), which couple said frame (2) respectively to said front wheel (3) and said rear wheel (4); characterized in that said rear suspension part (6b) comprises said at least two hybrid suspensions (15).

3. Saddle-type vehicle according to claim 2, wherein said rear wheel (4) defines a median plane (P) perpendicular to said second axis (B); said median plane (P) in turn defining two opposite sides of said rear wheel (4); characterized in that the at least two hybrid suspensions (15) are arranged on the respective opposite sides of said rear wheel (4).

4. A saddle-type vehicle according to claim 3, wherein said suspension system (6) further comprises at least one shock absorber (11), which is adapted to dampen the oscillations of said elastic element (7) and / or said hydropneumatic spring (8) of one of said at least two hybrid suspensions (15); said hydropneumatic spring (8) of said hybrid suspension (15) comprising a first part (16), which is spaced from said shock absorber (11) and a second part (17), which is mounted coaxially on said shock absorber (11); said first part (16) comprising, in turn: -a first chamber (20), which contains a gas at a pressure (p); said pressure (p) being directly proportional to said second stiffness (k2); - a second chamber (22) and a third chamber (23), which are fluidically connected to each other and contain an incompressible fluid; said first chamber (20) and said second chamber (22) being formed 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 sliding or deformable according to said internal volume (V) and the volume of said incompressible fluid transferred between said second chamber (22) and said third chamber (23); characterized in that said adjustment system (9) comprises an adjustment device (30) which is in fluidic communication with said second chamber (22) and / or with said third chamber (23) by means of one or more conduits (31); said conduits (31) and the volume of said second chamber (22) and / or said third chamber (23) defining a volume (W); said adjustment device (30) being adapted to vary said volume (W) so as to cause the sliding of said separating wall (21) and the variation of said second stiffness (k2).

5. Saddle-type vehicle according to claim 4, characterized in that said adjustment device (30) is in fluidic communication with said respective second chambers (22) and / or third chambers (23) of said two hybrid suspensions (15) included in said rear suspension part (6b); said adjustment device (30) being adapted to vary said volume (W) so as to cause the sliding of the respective separating walls (21) and the variation of the respective second stiffnesses (k2) of said two hybrid suspensions (15).

6. Saddle-type vehicle according to any one of the preceding claims, characterized in that said saddle-type vehicle is a scooter or moped.

7. Suspension kit (100) for a saddle-type vehicle (1) comprising: - at least two mechanical hydropneumatic hybrid suspensions (15); each of said hybrid suspensions (15) comprising, in turn, at least one elastic element (7) having a first stiffness (k1) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) of each hybrid suspension (15) being operationally coupled to each other and defining a variable equivalent stiffness (keq) of the respective hybrid suspension (15); and - an adjustment system (9) for adjusting said second stiffness (k2) of said respective hydropneumatic springs (8) of said hybrid suspensions (15), so as to vary said equivalent stiffness (keq) of said respective hybrid suspensions (15);said mechanical hydropneumatic hybrid suspensions (15) being adapted to be interposed between a part of the suspended mass (S) and a part of the unsprung mass (U) of said vehicle (1), which respectively have a first mass (s) and a;

8. second mass (u); the sum of said first mass (s) and said second mass (u) being equal to a total mass (M) of said vehicle (1); said unsprung mass part (U) resting, in use, on the ground (G). Kit according to claim 7, wherein each hydropneumatic spring (8) comprises a first part (16), which is adapted to be spaced from a respective shock absorber (11) of said saddle-type vehicle (1) and a second part (17), which is adapted to be coaxially mounted on said shock absorber (11); said first part (16) comprising, in turn: - a first chamber (20), which contains a gas at a pressure (p); said pressure (p) being directly proportional to said second stiffness (k2); - a second chamber (22) and a third chamber (23), which are fluidically connected to each other and contain an incompressible fluid; said first chamber (20) and said second chamber (22) being formed 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 sliding or deformable 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. characterized in that said adjustment system (9) comprises an adjustment device (30) which is in fluidic communication with said second chambers (22) and / or with said respective third chambers (23) by means of one or more conduits (31); said conduits (31) and the volume of said second chambers (22) and / or said third chambers (23) defining a volume (W); said adjustment device (30) being adapted to vary said volume (W) so as to cause the sliding of said separating wall (21) and the variation of said second stiffness (k2) respective of said two hybrid suspensions (15). Method for updating a saddle-type vehicle (1); said saddle-type vehicle (1) comprising, in turn: - a frame (2); - a front wheel (3), which can be steered relative to said frame (2) and can rotate around its own first axis (A); - a rear wheel (4), which is connected to said frame (2) so as to be able to rotate around its own second axis (B); - a suspension system (6) coupling said frame (2) to said front and rear wheels (3, 4) in a relative position of one with respect to the other, variable along a direction (Z) perpendicular to the ground (G); and - a motor (5) adapted to provide said front and / or rear wheel (3, 4) with traction torque; said process being characterized in that it comprises the steps of: (i) arrange at least two hybrid mechanical hydropneumatic suspensions (15) between a sprung mass portion (S) and an unsprung mass portion (U) of said vehicle (1), which respectively have a first mass (s) and a second mass (u); the The sum of said first mass (s) and said second mass (u) being equal to a total mass (M) of said vehicle (1); said unsprung mass part (U) resting, in use, on the ground (G); each of said at least two hybrid suspensions (15) comprising at least one elastic element (7) having a first stiffness (k1) and at least one hydropneumatic spring (8) having a second stiffness (k2); said elastic element (7) and said hydropneumatic spring (8) of each hybrid suspension (15) being operationally coupled to each other and defining an equivalent stiffness (keq) of said hybrid suspension (15), which is variable according to said relative position; and ii) fluidly connect said at least two hybrid mechanical hydropneumatic suspensions (15) to an adjustment system (9) to adjust said second stiffness (k2), so as to vary said equivalent stiffness (keq).

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