TECHNICAL FIELD

The present invention relates to the manufacture of saddle-ride vehicles. In particular, the invention relates to a motorcycle of scooter type comprising a quadrilateral rear suspension. STATE OF THE ART

Among the various types of motor vehicles available on the market, scooters or motor scooters are in great demand. These motorcycles are stands out from others for the presence of a frame which is substantially open in the intermediate part and for a footrest which enables the motorcyclist to maintain a riding position with an erect posture and closed and parallel legs. Scooters can have two wheels or three wheels with two steering front wheels and a driving rear wheel.

Compared to other motorcycles, a scooter also stands out by the fact that the engine block is not installed on the frame, but on the contrary is integral with the structure of the rear suspension swingarm. The swingarm-engine block assembly is hinged to the frame by means of a fulcrum so as to constitute a mass oscillating about said fulcrum as a result of loads acting on the rear suspension. In addition to the swingarm, the rear suspension typically comprises one or more spring-shock absorber assemblies interposed between the frame and the swingarm and/or between the frame and the engine block (see the layouts shown in Figures 1, 2 and 3 relating to known solutions).

Scooters are normally provided with rubber elements between the components of the rear suspension and the frame. In particular, these elements are normally provided at the ends of the spring-shock absorber assemblies and at the fulcrum about which the mass constituted by the swingarm and the engine block oscillates. In this respect, in order to limit the possible yaw movement of this mass with respect to the frame (i.e., the movement about a vertical axis), in many cases a block-holder frame is provided. This represents a sort of mechanical interface between the motorcycle frame and the oscillating mass so that the movements of the latter remain confined substantially to a horizontal plane. A known type of block-holder frame is schematically shown in the layouts shown in Figures 1 to 3 and indicated by the reference (T- RB). This comprises two connecting rods hinged together and having axes parallel to the axis of rotation of the rear wheel. A first connecting rod (Bl) is hinged to the motorcycle frame, while a second connecting rod (B2) is hinged to the oscillating mass (swingarm-engine) (F- BM) at a point hereinafter referred to as engine fulcrum (FM). To avoid a displacement of the engine fulcrum (FM), at least one point (D) of one of the two connecting rods (Bl, B2) is connected to the motorcycle frame by means of an element known as silent-block, consisting of two bushings with a rubber buffer therebetween. The two bushings, one being integral with the connecting rod and the other with the frame, can move relative to one another, temporarily losing their coaxial condition in a manner depending on the size and stiffness of the rubber used. In this configuration, the instant centre of rotation of the engine block varies continuously with respect to the frame, according to the stresses to which the silent-block is subjected.

As an alternative to or in combination with the aforementioned silent-block, two rubber elements (or rubber buffers) are provided at the pivots of the connecting rods (B1-B2) respectively hinged to the motorcycle frame and to the oscillating mass, or even at the hinge (C) between the two connecting rods (B1-B2).

As known, in addition to the vibrations generated by the engine, while the vehicle is moving the rear suspension is also subjected to other vertical and horizontal forces, generated by the contact between the rear wheel and the ground. The horizontal forces are generated by the traction and braking actions to which the motorcycle is subjected, while the vertical forces are generated by the reaction to the weight of the rear part of the vehicle and/or by the conformation of the road surface (presence of bumps or potholes) with which the rear wheel interacts.

With reference to the horizontal forces, these forces compress the rubber buffers (silent-block) of the frame-holder, thereby limiting to a certain extent the absorption by the buffers of the vibrations generated by the engine; however, this condition is accepted because of the need to transfer the thrust generated by the engine to the motorcycle frame. In fact, the motorcycle is pushed forward by means of said rubber elements.

It is known that vertical thrusts can be cancelled out by properly configuring the suspension, and more precisely by arranging the spring-shock absorber assembly so that the reaction develops in the same direction as the vertical force. In fact, to achieve this condition the springshock absorber assembly (AM) must be installed along the vertical direction passing through the axis of the rear wheel (RP), as schematically shown in Figure 1, in which the reference (T) indicates the motorcycle frame, while the reference (F-BM) indicates the mass oscillating about the fulcrum (F) configured by the block-holder frame (T-RB).

Still referring to Figure 1, in order to cancel out the vertical forces, the spring-shock absorber assembly (AM) shall therefore have a particularly set-back position, which evidently remains visible also on a lateral observation plane of the motor vehicle. Figures 2 and 3 schematically show two known solutions in which the spring-shock absorber assembly is inclined forward (Figure 2) or connected to the oscillating mass (swingarm-engine block) in a position close to the frame (Figure 3). Also in these solutions, however the spring-shock absorber assembly remains laterally visible.

It is known, however, that for scooters on the market, it is desired to locate the spring-shock absorber assembly in a more hidden position inside the motorcycle body. However, in scooters on the market, one possibility for achieving this aim could be to modify the body so that it extends substantially up to the height of the rear wheel hub. This solution clearly appears unfeasible, since it would make the aesthetics of the rear part of the motor vehicle and its maintenance more complex. Indeed, this solution would result in having always to disassemble the body in order to work on the engine and/or on the rear wheel.

In the configurations shown in Figures 2 and 3, as well as in other known configurations, the real position of the spring-shock absorber assembly (AM) thus differs from the ideal position shown schematically in Figure 1. Therefore, the reaction of the spring-shock absorber assembly (AM) is no longer aligned with the vertical force generated by the contact between wheel and ground. As a result, the rubber elements of the mechanical system are also pre-loaded vertically, thereby also transmitting stresses to the rear suspension.

The spring-shock absorber assembly (AM) is advanced towards the fulcrum of oscillation of the swingarm/engine mainly for reasons of size. In most cases, the spring-shock absorber assembly (AM) is inclined towards the front of the motorcycle so that the rubber elements, further to stresses on the rear suspension, are loaded not only vertically, but also horizontally. This obviously leads to a faster deterioration of the elements.

The Applicant has perceived the need for a new technical solution which on the one hand makes it possible to place the spring-shock absorber assembly in a hidden position, i.e., relatively advanced towards the fulcrum of oscillation of the swingarm/engine, and which at the same time makes it possible to cancel out, or at least greatly limit, the vertical forces on the rubber elements of the mechanical system in order to avoid their pre-loading.

SUMMARY

In view of the above considerations, the main task of the present invention is to provide a motorcycle that makes it possible to overcome or at least mitigate the drawbacks described above relating to the transmission of loads acting on the rear suspension to the motorcycle frame. Within this task, a first object is to provide a motorcycle in which the loads acting on the rear suspension are only partially transferred to the frame. In this respect, another object is to cancel out or at least limit as much as possible the transmission to the frame of vertical loads acting on the rear suspension. Yet another object of the present invention is to provide a motorcycle that is reliable and easily manufactured at competitive costs. The Applicant has noted that said task and said objects can be achieved by means of a scootertype saddle-ride motorcycle comprising a frame and a rear wheel operatively connected to the frame by means of a rear suspension comprising a swingarm which constitutes, fully or partially, a mass oscillating with respect to the frame around a first axis of rotation. According to the invention, the rear suspension comprises a long rod hinged to the frame about a second axis of rotation different from the first axis of rotation. The suspension also comprises a short rod hinged to the long rod about a third axis of rotation; in particular, the short rod is rotatably connected, directly or by means of the swingarm, to the pivot of the rear wheel so as to rotate about a fourth axis of rotation; in at least one operating condition of the rear suspension, the third axis of rotation and the fourth axis of rotation lie on a substantially vertical plane containing the axis of rotation of the rear wheel. The rear suspension also comprises a springshock absorber assembly connected, at a first end thereof, to the long rod and, at a second end thereof, to the frame.

According to a possible embodiment, the swingarm is connected to an engine block of the motor vehicle. In this embodiment the swingarm and the engine block are part of said oscillating mass. According to a possible embodiment, the short rod is directly hinged to the pivot of said rear wheel and is disengaged from the swingarm; in this embodiment the fourth axis of rotation coincides with the axis of rotation of the rear wheel.

According to another embodiment, the short rod is hinged to the swingarm and the fourth axis of rotation is distinct from the axis of rotation of said rear wheel.

According to one embodiment, the length of said long rod, considered along a theoretical line orthogonal to the second axis of rotation and to the third axis of rotation, substantially corresponds to the length of the oscillating mass, considered along a second theoretical line orthogonal to the first axis of rotation and to the axis of rotation of the rear wheel.

In a possible embodiment, the long rod and the short rod are located above a theoretical line orthogonal to the axis of rotation of the rear wheel and to the first axis of rotation, wherein said position is considered on a lateral observation plane of the motorcycle.

According to a possible embodiment, the spring-shock absorber assembly is arranged within a body so as not to be visible when the motor vehicle is observed on a lateral observation plane. In a possible alternative embodiment, the long rod and the short rod are located below a theoretical line orthogonal to the axis of rotation of the rear wheel and to the first axis of rotation, wherein said position is considered on a lateral observation plane of the motorcycle. In a possible embodiment, the short rod supports a braking device configured to brake the rear wheel. According to a possible embodiment, the swingarm comprises a first part and a second part, wherein the first part is folded inwards with respect to the second part; said first part being rigidly connected to the engine block and said second part being rotatably connected to the pivot of the rear wheel.

In one embodiment, the spring-shock absorber assembly is connected to the long rod at an intermediate point between the two ends thereof or at one end of the long rod.

In a possible embodiment, the long rod comprises a tubular body comprising a section configured as an arc and at least one plate made of metallic material connected at its ends to the tubular body in a position facing the arc section, wherein an end of the spring-shock absorber assembly is connected to the tubular body at the arc section.

According to a possible embodiment, for each half-plane identified by a longitudinal plane of symmetry of the rear wheel orthogonal to its axis of rotation, the rear suspension comprises a long rod and a short rod hinged to the corresponding long rod, wherein the long rod located in one half-plane is connected to the long rod located in the other half-plane by means of at least one connecting member so that the two long rods move as a single translating body; said long rods and said short rods being arranged in a mirror-like manner with respect to the longitudinal plane of symmetry.

With reference to the embodiment just mentioned, preferably, but not exclusively, the rear suspension comprises two spring-shock absorber assemblies, each comprising a first end connected to a long rod and a second end connected to said frame, wherein said spring-shock absorber assemblies are arranged in a substantially mirrored position with respect to the longitudinal plane of symmetry.

In a possible variant, for each spring-shock absorber assembly, the first end is connected to a corresponding long rod in a position thereof between said first axis and said second axis.

LIST OF THE FIGURES

Further characteristics and advantages of the invention will become more apparent from the following detailed description of some preferred, but not exclusive, embodiments of a vehicle, illustrated herein for indicating and non-limiting purposes, with the aid of the accompanying drawings, wherein:

- Figures 1, 2 and 3 are schematic views of a rear suspension of a motorcycle of scooter type of the prior art;

- Figure 4 is a schematic view of a first embodiment of a rear suspension of a saddle-ride motorcycle according to the present invention;

- Figure 4A is a view of the rear part of a motorcycle according to the invention comprising the suspension of Figure 4;

- Figure 4B is a view of a component assembly of the suspension of Figure 4A;

- Figure 5 is a schematic view of a second embodiment of a suspension according to the present invention;

- Figure 5 A is a schematic view of a third embodiment of a suspension according to the present invention;

- Figure 5B is a schematic view of a fourth embodiment of a suspension according to the present invention;

- Figures 6 and 6A relate to a fifth embodiment of a rear suspension of a motorcycle according to the present invention;

- Figures 7 and 7A relate to another embodiment of a rear suspension of a motorcycle according to the present invention;

- Figure 8 is a schematic view of a further embodiment of a rear suspension of a vehicle according to the present invention;

- Figure 8A is a view of the rear part of a motorcycle according to the invention comprising the rear suspension of Figure 8;

- Figure 8B is a view of a component assembly of the suspension of Figure 8 A;

- Figure 9 is a schematic view of a further embodiment of a rear suspension of a vehicle according to the present invention;

- Figure 9A is a view of the rear part of a motorcycle according to the invention comprising the rear suspension of Figure 9;

- Figure 9B is a view of a component assembly of the suspension of Figure 8 A;

- Figures 10 and 11 are views of a component assembly of further possible embodiments of a rear suspension of a motorcycle according to the present invention.

DETAILED DESCRIPTION

With reference to the aforementioned figures, the present invention therefore relates to a saddleride vehicle 1, wherein with this expression it is meant any motorbike or motorcycle having at least two wheels, i.e., at least one front wheel and at least one rear wheel. Therefore, this expression also includes three-wheeled motorcycles, having two front steering wheels and a rear driving wheel, or alternatively a front steering wheel and a pair of rear driving wheels. Hereinafter, the saddle-ride vehicle will be indicated more simply by the term motorcycle 1.

Figures 4, 4A and 4B relate to a first possible embodiment of a motorcycle 1 according to the invention. The motorcycle 1 comprises a frame 12 to which a front wheel 4 and a rear wheel 2 are operatively connected. In particular, the rear wheel 2 is connected to the frame 12 by means of a rear suspension 3 which includes a swingarm 21 integral with an engine block 100. By the term “engine block” it is generally meant the structure that incorporates the engine of the motorcycle 1 and/or the mechanical transmission through which the torque generated by the engine is transferred to the rear wheel. The frame 12 supports a body 13, wherein with this term it is generally meant an assembly of components that together constitute the outer protective covering of the motor vehicle 1.

The swingarm 21 is connected to the frame 12 by means of connecting means defining a first axis of rotation 31, hereinafter also indicated by the term fulcrum 31. The swingarm forms, fully or partially, an oscillating mass M which oscillates about said first axis of rotation 31. In a first embodiment, visible in the figures, the swingarm 21 is rigidly connected to the engine block 100. Therefore, in this configuration, the oscillating mass M comprises the swingarm 21 and also the engine block 100. In the layout shown in Figure 4, as well as in other layouts shown in the accompanying figures, the oscillating mass M is purposely split into two parts by a dashed line in order to identify, in a purely schematic and indicative way, the swingarm 21 and the engine block 100. In an embodiment alternative to that just described above (and not visible in the figures), the swingarm is separated from the engine block, which can, for example, be arranged inside the volume of the rear wheel rim, i.e., directly connected to the wheel hub, according to a configuration known as “wheel hub motor”. In this case, the engine block is not part of the mass oscillating about the aforementioned fulcrum.

It should be noted, however, that the type of propulsion used to generate the driving torque is not relevant to the invention. The propulsion type can be thermal or electric. Alternatively, the propulsion can be of a hybrid type, i.e., a propulsion comprising a thermal engine and an electric motor that can operate independently or in combination according to known principles. An example of a hybrid propulsion system is shown and described in patent EP 1572486 to the same Applicant.

The oscillating mass M (whether constituted by the swingarm 21 alone or by the assembly comprising the swingarm 21 and the engine block 100) is in any case connected to the frame 12 by means of connecting means defining the first axis of rotation 31. These connecting means may consist of a single pivot or alternatively of a connecting frame, for example a block-holder frame such as that described above in connection with the prior art. In any case, preferably at least one rubber element is provided to limit the transmission of the vibrations generated by the engine to the frame. In the case of a connecting frame, the rubber element can be formed by the “silent-block” according to a known solution already described above. The swingarm 21 rotatably supports the rear wheel 2 in order to allow it to rotate about an axis of rotation 101 (hereinafter indicated by the term wheel axis 101) which is located in a distal position relative to the fulcrum 31, substantially at an end of the oscillating mass M opposite the end near which the fulcrum 31 is located. At the same time, the mass M oscillates about the axis of rotation 101 with respect to the rear wheel 2.

The rear suspension 3 comprises a bar 51 (or long rod 51) hinged to the frame 12 at a second axis of rotation 32 different from the abovementioned fulcrum 31. In particular, the term “different” is used to indicate a condition whereby the second axis of rotation 32 is located in a position different from the fulcrum 31, wherein said position is considered on a lateral plane of the motorcycle 1 (plane of Figure 4).

The rear suspension 3 also comprises a connecting rod 52, or short rod 52, which is hinged to the long rod 51 at a third axis of rotation 33. In this respect, in the layout shown in Figure 4, the second axis of rotation 32 and the third axis of rotation 33 are defined at opposite ends of the long rod 51. The connecting rod 52 is rotatably connected directly to the pivot of the rear wheel 2 at a fourth axis of rotation which, in the embodiment shown in Figures 3 A-3B, coincides with the axis of rotation 101 of the rear wheel 2. The connecting rod 52 therefore retains one rotational degree of freedom, about the pivot of the rear wheel 2, with respect to the oscillating mass M.

In particular, assuming that the motorcycle 1 is resting on a horizontal plane PO, the third axis of rotation 33 is coplanar with the axis of rotation 101 of the rear wheel 2. More precisely, the axis of rotation 101 of the rear wheel 2 and the third axis of rotation 33 (between the connecting rod 52 and the crank 51) lie on the same vertical or substantially vertical plane PV.

The rear suspension of the motorcycle 1 also comprises a spring-shock absorber assembly 70 having the purpose of dampening the oscillation and/or slowing down the movement of the suspension (i.e., of the assembly including the wheel, the oscillating mass M, the long rod 51, the connecting rod 52) with respect to the frame 12. The spring-shock absorber assembly 70 may take on a per se known configuration and is operatively placed between the long rod 51 and the frame 12. More precisely, a first connecting end 70Ais hinged to the long rod 51, while a second connecting end 70B, opposite the first connecting end 70A, is hinged to the frame 12 at a position different from that taken by the first axis of rotation 31 and by the second axis of rotation 32, wherein this position as well is considered from a lateral observation plane of the motorcycle 1.

As apparent from Figure 4, the suspension of the motorcycle 1 is configured as a quadrilateral, wherein the long rod 51 and the oscillating mass M constitute two “cranks ” hinged on one side to the frame 12 and on the other side to the connecting rod 52defined above. As a result of this arrangement, the long rod 51, the spring-shock absorber assembly 70 and the frame 12 constitute a separate assembly which exchanges only direct loads with the oscillating mass M in the same way as the connecting rod 52. As a result of the vertical arrangement of the connecting rod 52 (mutual orientation of axes 33 and 101), the vertical component of the loads acting on the suspension is not transferred to the frame 12 and therefore does not affect the rubber element(s) (silent-block). These elements are only affected by the possible horizontal component of the loads.

Figure 4B shows a perspective view of a component assembly of the rear suspension shown in Figure 4. In particular, it can be seen that the rear suspension 3 is asymmetrical with respect to a longitudinal plane of the motorcycle 1 which is orthogonal to the axis of rotation of the rear wheel 2 and forms a plane of symmetry for the same wheel. This longitudinal plane evidently identifies two half-planes. The long rod 51, the connecting rod 52 and the spring-shock absorber assembly 70 are arranged in a same half-plane. As shown in Figure 4A, preferably, but not exclusively, said half-plane is opposite to the half-plane in which the portion of the engine block 100 is located, in which the transmission that connects the engine contained therein to the rear wheel 2 is located.

Still referring to Figures 4A and 4B, the swingarm 21 appears as a shaped bracket rigidly connected to the engine block 100 by means of suitable connecting elements, so as to form the oscillating mass M described above. In this respect, in Figure 4B the references XI and X2 indicate the connecting axes with the engine block 100 (axes of the connecting screws). Preferably, said bracket is shaped so as to define a first part 210A, directly connected to the engine block 100, folded inwards with respect to a second part 210B, rotatably mounted on the pivot of the rear wheel 2 and extending in a more outward position with respect to the first part 210A. The inward folding of the first part 210A makes it possible to locate the long rod 51 in a position substantially adjacent to the rear wheel 2 (see Figure 4A) so as to reduce as much as possible the transverse dimensions of the rear suspension 3.

Still referring to Figure 4B, the folded bracket portion 210 may also be used to support a muffler (not shown in the figures). In this respect, references X3 and X4 in Figure 4B indicate the connecting axes between the bracket-shaped swingarm 21 and the muffler (not shown in the figures for the sake of clarity). In this sense, the positioning of the muffler is also facilitated by folding of the bracket into two parts as described above.

Still referring to Figures 4A and 4B, according to a preferred embodiment, the connecting rod 52 of the rear suspension also supports a brake calliper 80 which acts on the rear wheel 2 to brake it. By the term “brake calliper” 80 it is generally meant the component assembly acting on a “disc brake ” integral with the rear wheel 2 according to a widely known principle. It has been noted that this solution is particularly advantageous since the instant centre of rotation of the suspension moves towards the fulcrum 31, thereby making the behaviour of the motorcycle 1 when braking particularly stable.

Figure 5 shows a schematic view of a possible variant of the suspension shown in Figures 4 to 4B. In particular, a first theoretical line LI is identified, which is orthogonal to the second axis of rotation 32 and to the third axis of rotation 33 and substantially parallel to a second theoretical line L2 orthogonal to the fulcrum 31 and to the wheel axis 101. The length of the long rod 51, considered along the first theoretical line LI, corresponds to the distance between the second axis of rotation 32 and the third axis of rotation 33. On the other hand, the length of the oscillating mass M, considered along the second theoretical line L2, substantially corresponds to the distance between the wheel axis 101 and the fulcrum 31. In the suspension shown in Figure 5, the connecting rod 52 is disengaged from the oscillating mass M and remains always vertically oriented and can freely oscillate about the pivot of the rear wheel. The two “cranks” (rod 51 and mass M) of the quadrilateral are substantially parallel to one another and have the same length. As a result of this arrangement, the load bearing on the suspension is not transmitted to the fulcrum 31 and thus to the frame 12.

Figure 5 A relates to a further possible variant of a rear suspension of a motorcycle 1 according to the invention, whose general layout can in any case be traced back to that shown in Figures 4 to 4B. In this further variant, the connecting rod 52 is indirectly connected to the wheel body through the oscillating mass M. More precisely, the connecting rod 52 is hinged to the oscillating mass M at the fourth axis of rotation 34 which, in this case, is not coaxial to the wheel axis 101. In this embodiment, at least in the condition where the suspension is unloaded, the fourth axis of rotation 34 and the third axis of rotation 33 nevertheless lie on a vertical plane PV passing through the wheel axis 101.

In the variant shown in Figure 5A, the fourth axis of rotation 34 oscillates integrally with the oscillating mass M and more precisely moves along a circumference concentric to the wheel axis 101. Therefore, in this embodiment, while on the one hand the vertical loads are cancelled out, on the other hand the horizontal component of these loads is transmitted to the rubber elements (e.g., silent block) intended to absorb the vibrations between the oscillating mass M and the frame 12 of the motorcycle 1.

Figure 5B relates to a further embodiment of a rear suspension that, keeping other components the same, differs from the embodiment shown in Figure 5A substantially by a different configuration of the long rod 51. Indeed, in the variant shown in Figure 5B, the long rod 51 is hinged to the connecting rod 52 at the third axis of rotation 33 defined substantially at a first end 511 of said long rod 51. The long rod 51 is also hinged to the frame 12 through the second axis of rotation 32 defined at an intermediate point between the two ends 511, 512 of the long rod 51. According to the invention, the spring-shock absorber assembly 70 is in any case operatively interposed between the long rod 51 and the frame 12. More precisely, in the case shown herein, a first end 70A of the spring-shock absorber assembly 70 is connected to the long rod 51 at the second end 512 thereof, while the second end 70B of the spring-shock absorber assembly 70 is hinged to the frame 12 according to the principles of the invention.

In this embodiment, the spring-shock absorber assembly 70 takes up a very advanced, and therefore particularly hidden, position, other advantages in terms of reduced loads transferred to the suspension and provided by the suspension to the body in terms of stress transmission remaining the same.

Figures 6 and 6A relate to another embodiment that differs from those described above substantially by a different shape of the long rod 51 of the rear suspension 3. In particular, in this embodiment, the long rod 51 is configured as a sort of leaf spring. In detail, the long rod 51 comprises a preferably tubular body provided with a section 511 configured as an arc. The long rod 51 comprises one or more plates 512 made of metallic material (preferably steel) which are connected, at their ends, to the section 511 to create a state of tension in accordance with the operating principle of a leaf spring. The spring-shock absorber assembly 70 is operatively interposed between the section 511 configured as an arc of the long rod 51 and the frame 12. Therefore, a first end 70A of the spring-shock absorber assembly 70 is connected to section 511 configured as an arc, while the opposite end 70B is connected to the frame 12.

The use of a long rod 51 with a leaf spring configuration makes it possible to improve the suspension response to the loads acting on the rear suspension 3.

It should be noted that the other components of the suspension 3 (connecting rod 52, oscillating mass M) shown in Figures 6 and 6A have substantially the same function and the same behaviour as described above for the corresponding elements of the suspension shown in Figure 4. Furthermore, the long rod 51 described in connection with Figures 6 and 6A could be used, mutatis mutandis, to create a suspension according to any of the suspension layouts shown in Figures 4, 5, 5 A, and 5B.

Figures 7 and 7A relate to a further possible variant which also differs by the shape of the long rod 51, which is different from those described above. In this further variant, the long rod 51 is configured to behave substantially like a “torsion bar”. In this configuration, the term “long rod 51 ” is thus used to indicate an assembly of components that together configure a torsion bar system. This assembly comprises a hexagonal bar (not visible in the figures) and an adjustment device 91 configured to vary the rigidity of the hexagonal bar. In the case shown herein, the hexagonal bar is located inside a hollow tubular element 92 hinged at one end to the connecting rod 52 at the third axis of rotation 33 and to the frame 12 at the second axis of rotation 32. More precisely, one end of the hexagonal bar is rigidly connected to an end of the hollow tubular element 92. The spring-shock absorber assembly 70 of the suspension 3 is connected, at the lower end thereof 70A, to the hollow tubular element 92 and at an upper end 70B to the frame 12.

For the torsion bar to work correctly, a strut 96 is provided comprising two rod ends. The upper rod end 96Ais connected to the frame 12, while the lower rod end 96B is connected to a locking element 97 coupled with the hexagonal bar and configured to lock the rotation thereof along its axis Z (indicated in Figure 7A) when the shock absorber assembly 70 becomes shorter because of the loads acting on the suspension 3. The locking element 97 is mounted on the hexagonal bar with a torsionally rigid coupling, but it can slide along the axis Z of the hexagonal bar. The adjustment device 91 comprises a toothed wheel 81 mounted around the hexagonal bar and an activation knob 82 for rotating the toothed wheel 81. The locking element 97 is coupled to the hexagonal bar so as to move along the hexagonal bar following a rotation of the activation handle 82. The movement of the locking element 97 along the hexagonal bar results in a variation in the rigidity of the bar. Indeed, said rigidity depends on the length of the hexagonal bar, in other words the distance between the end integral with the containment body 92 and the position assumed by the blocking element 97 along the bar. It can be noted that rod ends (ends 96A, 96B) of the strut 96 are provided not only to follow the rotation of the hexagonal bar, but also to follow the movement of the locking element 97 along the bar. Advantageously, the coupling between the worm screw of the activation knob 82 and the toothed wheel 81 constitutes a coupling with low mechanical efficiency and therefore makes movement of the hexagonal bar along the Z axis irreversible.

Overall, this particular shape of the long rod 51 increases the ability of the suspension to react to the loads acting on the suspension.

In the embodiments of the rear suspension described above and shown in Figures 3 to 7B, the connecting rod 52, the long rod 51 and the spring-shock absorber assembly 70 are located in a position above the theoretical line L2 orthogonal to the fulcrum 31 and to the wheel axis 101 (see for example the layout shown in Figure 5). Conversely, in the embodiment shown in Figure 8, the long rod 51 and the connecting rod 52 are positioned below said theoretical line L2. In any case, according to the invention, the long rod 51 is hinged to the connecting rod 52 and to the frame 12, while the spring-shock absorber assembly 70 is positioned between the long rod 51 and the frame 12.

In this respect, in the embodiment shown in Figure 8, the spring-shock absorber assembly 70 is connected to the long rod 51 in a position between the second axis of rotation 32 and the third axis of rotation 33. However, in an alternative solution, not shown in the figures, the springshock absorber assembly 70 could be connected to the long rod 51 in a position not between the two axes 32, 33 indicated above.

Figure 8 A relates to a motorcycle 1 comprising a rear suspension according to the layout shown in Figure 8. It can be noted that with respect to the layout shown in Figure 8, in the embodiment shown in Figure 8 A the connecting rod 52 is not disengaged from the swingarm 21, but rather is hinged thereto, i.e., to the oscillating mass M, at the fourth axis of rotation 34. When no loads act on the rear suspension, the third axis of rotation 33 and the fourth axis of rotation 34 lie on a vertical plane containing the wheel axis 101. The mutual arrangement of the two axes of rotation 33-34 just mentioned above can be clearly seen also in Figure 8B, in which the components of the rear suspension 3 are illustrated. As a result of the loads, the position of the third axis of rotation 33 is affected by the oscillations of the swingarm 21 (and generally of the oscillating mass M) according to a principle substantially similar to that described above in connection with the suspension layout shown in Figure 5A.

In the embodiments of the rear suspension 3 described above and shown in Figures 3 to 7B, the rear suspension has a substantially asymmetrical configuration relative to the longitudinal plane PL described above. Indeed, the suspension components are all arranged on a same half-plane identified by said longitudinal plane PL. Figures 9 to 9C, on the other hand, refer to a further embodiment in which the rear suspension 3 has a substantially symmetrical configuration relative to the longitudinal plane PL. In this case, for each half-plane, the rear suspension 3 comprises a long rod 51 A rigidly connected to the other long rod 5 IB arranged on the other half-plane. In this respect, connecting elements 53 are provided which rigidly connect the two long rods 51 A, 5 IB so that they behave as a single translating body. In the case illustrated in Figures 9A, 9B, 9C, the connecting elements 53 extend in a transverse direction.

Still referring to Figures 9 to 9C, for each half-plane identified by the longitudinal plane PL, the rear suspension 3 comprises a connecting rod 52A, 52B hinged to the corresponding long rod 51 A, 5 IB. In this respect, each connecting rod 52A, 52B is hinged to the oscillating mass M according to the same principle described above in connection with Figure 5B. In general, for each half-plane, the suspension shown in Figure 9 has a configuration substantially similar to that described above with reference to Figure 5B.

In the embodiment shown in Figures 9 to 9C, a first spring-shock absorber assembly 70 and a second spring-shock absorber assembly 70’ are provided each operatively located between the frame 12 and a corresponding long rod 51 A, 5 IB of the rear suspension 3. In particular, in the case illustrated, a first end of each spring-shock absorber assembly 70, 70’ is connected to the free end of a corresponding long rod 51 A, 5 IB, while the second end is connected to the frame 12, according to the same principle of the layout shown in Figure 5B. Indeed, each long rod 51 A, 5 IB is hinged to the frame 12 at an intermediate point thereof, according to the same principle shown in the layout of Figure 5B.

Figure 10 relates to a first possible construction variant of the symmetrical suspension described with reference to Figures 9 to 9C. In particular, this construction variant has a different positioning of the spring-shock absorber assemblies 70, 70’. Each of these assemblies is in fact connected to the corresponding long rod 51 A, 5 IB at a point thereof substantially between the second axis 32 and the third axis 33.

Figure 11 relates to a possible construction variant of the symmetrical suspension mentioned above in reference to Figures 9 to 10. In the embodiment shown in Figure 11, there is a single spring-shock absorber assembly 70 arranged on one side of the suspension (i.e., on one of said half-planes) and connected at a first end to one of the two long rods 51; 5 IB of the suspension, and at a second end to the frame 12. Otherwise, the layout of the rear suspension shown in Figure 11 is substantially the same as that shown in Figure 9, in that it has a pair of long rods 51 A provided with a free end hinged to the frame 12 at the second axis of rotation 32. The suspension shown in Figure 11 also comprises a pair of connecting rods 52A, 52B each of which is hinged to a corresponding long rod 51 A, 5 IB through the third axis of rotation 33 and substantially at the free end of the long rod 51 A, 5 IB. Still referring to Figure 10, the long rods 51 A, 5 IB are connected to one another by transverse elements 53 so as to move as a single translating body. The two connecting rods 52A, 52B are defined by two opposite portions of a substantially U-shaped body, wherein the transverse portion, connecting said opposite portions, is hinged to the two long rods 51 A, 5 IB.

As apparent from the layouts shown in Figures 4, 5, 5A, 5B, 9, in many of the embodiments described above the spring-shock absorber assembly 70 is located in a position inside the body 13 of the motor vehicle 1, wherein said position is considered on a lateral observation plane (coinciding with the observation plane of the abovementioned figures). Advantageously, the advanced position of the spring-shock absorber assembly 70, enabled by the quadrilateral suspension, allows the assembly to remain hidden inside the body 13, differently from a traditional scooter, where the suspension is always visible from the side.

The motorcycle according to the invention fully achieves the tasks and objects previously set out. In particular, the quadrilateral configuration of the suspension eliminates, or at least greatly reduces, the transmission to the frame of loads acting on the rear suspension when using the motorcycle.