FLYWHEEL FOR MUSCLE EXERCISING EQUIPMENT AND EQUIPMENT PROVIDED WITH THE SAID FLYWHEEL DESCRIPTION

The present invention concerns a flywheel for muscle exercising equipment and in particular equipment in which the resistance force is provided by a rotating inertial mass, known as "flywheel" in jargon. The invention also concerns equipment of this type provided with the aforesaid flywheel.

The present invention relates to the field of exercise machines in which the resistance exerted by the muscles of the person is generated exclusively, or prevalently, by the inertia of one or more flywheels made to rotate by this person.

In particular, the invention regards the field of isoinertial machines, in which the aforesaid resistance is provided both in the concentric phase and in the eccentric phase of the movement of the exercise.

The force of the person is transmitted to the flywheel through a flexible element, such as a belt, a rope or the like, which is repeatedly wound around and unwound from a shaft that rotates integrally with the flywheel.

During the concentric phase of the movement, the flexible element is put under tension so that unwinding thereof causes rotation of the flywheel.

When the flexible element has been completely unwound, at the end of the concentric movement, the flywheel continues to rotate, due to its inertia, rewinding the flexible element in the opposite direction. In this subsequent eccentric phase of the movement, the part of the body engaged in the exercise is drawn in the opposite direction by the flexible element.

Equipment of isoinertial type with the aforesaid features is described in the prior art patents US 1783376 A, US 3841627 A and WO 90/10475 Al . A common feature of these prior art machines is the fact that they comprise a flywheel, or inertial mass, generally consisting of one or more discs, typically made of metal, having a specific volume and a well-defined geometry and, therefore, also a given mass.

However, in these machines, the resistance opposing the force exerted by the person does not only depend on the mass of the flywheel but also on its moment of inertia; in fact, a different distribution of the same mass with respect to the rotation axis determines a different resistive force at a given rotation speed.

Prior art isoinertial equipment is generally provided with a series of flywheels, with different moment of inertia values, so that they can be used by people with different physical performances or by the same person to perform exercises that involve the use of different muscles and that can develop forces that can differ greatly.

Therefore, when the person requires to change the type of exercise or when the equipment is used by another person, it is generally necessary to replace the flywheel mounted on the machine at the time with another flywheel having the correct moment of inertia.

For this purpose, in prior art machines the supporting shaft of the flywheel has at least one free and accessible end for mounting or removing the aforesaid flywheel. At times, the shaft has two free ends, on each of which at least one flywheel can be mounted.

However, the prior art machines produced in this manner have some problems.

Firstly, the operation to replace the flywheel requires some time. At times this can interfere with the person's training, especially at competitive level, such as in a situation in which an athlete is required to perform a certain number of series of repetitions using a different flywheel for each. However, even at amateur level, the operations to mount and remove the flywheel with a certain frequency can be tiresome.

Moreover, although not particularly complicated, these operations involve handling a mass of several kilograms, which can be dangerous for a person with little experience or with limited physical abilities. Further, it is important for the flywheel to be mounted correctly on the shaft so that following rotation, which reaches speeds of a several tens or hundreds of rpm, it cannot become detached and strike people close to the machine. For these reasons, these operations are often performed by skilled personnel who assist the user.

Finally, the aforesaid configuration of prior art machines and flywheels requires a machine to be equipped with a set of flywheels (for example three, four or more) to allow the machine to be used by any person and for any kind of exercise.

In a sporting environment, such as a gym, where a certain number of machines can be installed, it is necessary to purchase the same number of sets of flywheels as the number of machines, with considerably costs.

The limits of prior art machines also emerge when they require to be moved or transported for use in another place,

such as when athletes wish to take the machine with them while traveling to continue their training program or when rehabilitation specialists require to work outside the medical center, for example at a patient's home, or at other structures in which they work.

In these situations, considering the weight and bulk of the set of flywheels, having to carry them does not facilitate the aforesaid transport operations.

Some of the problems indicated above with reference to isoinertial machines are also common in other types of exercise equipment in which the resistance is generated prevalently, or exclusively, by the inertia of a rotating mass.

The patent US 6283899 Bl describes an exercise machine of isoinertial type in which the flexible element can be wound around a conical spool. The travel of the flexible element can be guided along different paths so as to vary both the winding zone of the element on the spool and the angle of intersection of said flexible element with respect to the rotation axis. These variations of position allow adjustment of the resistance transmitted to the person through the flexible element. However, the machine thus produced is very bulky, in particular due to the length of the spool, which must allow winding on different diameters and the presence of pluralities of guide pulleys to guide the flexible element. Moreover, this configuration does not allow the use of flat flexible elements, such as belts or the like, or flexible elements formed by a bundle of separate elements, typical of these applications.

Moreover, with the aforesaid prior art machine, it is difficult to establish the correct configuration of the guide pulley to obtain the desired resistance.

Finally, the conical surface of the spool determines, in any case, a slight variation of resistance, as the flexible element is wound on a conical segment having a diameter that is not constant.

In this context, the object of the present invention is to provide a flywheel for muscle exercising equipment that solves the problems of the prior art described above.

In particular, an object of the present invention is to propose a flywheel that allows practical and rapid variation of the resistance of an isoinertial machine or, more generally, equipment provided with a rotating inertial mass.

Another object of the present invention is to provide a flywheel for muscle exercising equipment that can be safely handled even by unskilled personnel.

A further object of the present invention is to propose a flywheel with a system for adjusting the inertia that is simple and inexpensive to produce.

These and other objects are achieved by a flywheel, which can be mounted on muscle exercising equipment, destined to be rotated to generate an inertia, said flywheel comprising parts, and more specifically masses, that can be moved toward or away from the rotation axis. This movement determines, with the same mass (weight) of the flywheel, a variation of the moment of inertia of the flywheel and therefore of its inertia when it is rotated.

The masses can be positioned in various positions between a maximum distance and a minimum distance from the rotation axis. By positioning the masses at a given distance it is possible to obtain a flywheel that offers a certain resistance to the person performing the exercise.

The same flywheel can therefore be used by subjects with very different physical performances or to perform exercises that involve the use of different muscles with different levels of development.

With the flywheel of the present invention, no operations are required to replace the flywheel when the resistance offered by the machine requires to be varied, overcoming the problems described above.

Movement of the masses can be carried out by repositioning each single mass manually or by means of mechanisms that move them in a simultaneous and coordinated manner. Blocking of the masses in the position of use can take place automatically or by acting on suitable blocking means.

Therefore, the flywheel according to the present invention comprises:

- at least one support , connectable integral with a rotating part of the machine; and

- at least two masses, connected to the support with the possibility of moving between a position of minimum distance and a position of maximum distance from the rotation axis.

The movement of the masses between said position of minimum distance and said position of maximum distance causes a variation of the moment of inertia of the flywheel and therefore a variation of the inertia at a given rotation speed.

Generally, but not necessarily, the maximum and minimum values of the moment of inertia of the flywheel correspond to the aforesaid positions of maximum and minimum distance from the rotation axis. In the context of the present invention, the term movement means a translation or a rotation movement, or the combination of these two movements.

Therefore, the masses can translate rigidly along a route with respect to the rotation axis of the flywheel or, alternatively or additionally, can rotate around a fixed point on the support. Also in this second case, as a function of the shape of the mass, rotation can determine movement of the centroid of the mass with respect to the rotation axis and therefore variation of the moment of inertia of the flywheel.

According to the invention, the masses comprise blocks which can substantially have any regular or irregular geometrical shape. For example, said blocks can have the shape of a parallelepiped, polyhedron, cylinder, sphere or mixed shapes.

In an aspect of the invention, the flywheel can comprise guide means adapted to guide the movement or the rotation of said masses along a given route. This route can, in fact, be rectilinear or curved, for example in a circular arc.

Marks such as notches, numbers, etc., can be provided on the support or on another suitable part, to allow correct positioning of the masses, for example at the same distance from the rotation axis, to maintain the flywheel balanced.

In another aspect of the invention, the flywheel can comprise releasable blocking means, adapted to block the masses on the support in positions at a given distance from the rotation axis. Said positions are generally two or more, comprised between the positions of maximum distance and minimum distance from the rotation axis. Suitable blocking means can be screw, interlocking, magnetic or similar means.

In another aspect of the invention, the flywheel can comprise elastic means that act on said masses. In detail, said elastic means are adapted to exert a force of repulsion or of attraction on said masses respectively to move them away from or toward the rotation axis, or both.

Said elastic means can for example comprise coil or torsion springs, elastic ropes or tapes, or pads made of expanded material.

In another aspect of the invention, the masses, two or more, are identical to one another and are, in any position between the position of minimum distance from the rotation axis and the position of maximum distance from the rotation axis, evenly spaced angularly. This allows the flywheel to be maintained balanced and prevents the occurrence of vibrations during use of the machine.

In another aspect of the invention, the guide means of the masses can comprise tracks obtained in the support. A slider integral with said masses can be housed slidingly in the tracks. Said slider can be obtained in one piece in the block of the mass or joined thereto.

In a preferred variant, the tracks are rectilinear and arranged radially with respect to the rotation axis. However, the tracks can also have a partially or totally curved trend. In general, the tracks, whether rectilinear or curved, lie in a common plane, perpendicular to the rotation axis.

According to another variant, said guide means comprise rotating joints, such as hinges, pin/hole couplings or the like, to rotate the mass with respect to a fixed point of the support.

The aforesaid guide means can be combined with one another to guide both translation and rotation of the mass.

In another aspect of the invention, the flywheel can comprise adjustment means adapted to control the simultaneous and coordinated movement of the masses toward the rotation axis or away from this latter. The terms simultaneous and coordinated mean that the masses, under the action of the adjustment system, are always maintained at the same distance from said rotation axis or, in any case, in a position in which the flywheel is substantially balanced.

Therefore, said adjustment means facilitate the operations of variation of the moment of inertia of the flywheel, operations that can be also be carried out by people without much experience and without particular training.

According to a preferred variant, said adjustment means comprise:

- at least one hub hinged to the support, preferably at the rotation axis; and

- drive guides, obtained on the hub, adapted to slidingly house drive pins of each mass. Following the rotation of the hub with respect to the support, said drive guides engage the drive pins so that the masses are moved toward the rotation axis or away from this latter.

Rotation of the hub can be imparted manually, for example by means of a hand grip, or automatically, for example by an electric motor.

According to this variant, the blocking means can act directly on the hub in order to block this latter and the masses with respect to the support.

The blocking means can also be combined with the aforesaid hand grip means.

In a preferred aspect of the invention, the drive tracks have a curved profile. The hub thus configured can be used in combination with the support provided with rectilinear guide tracks.

In fact, the constraint provided by the slider in the guide track ensures that the action of the drive track on the drive pin causes the movement of the mass along said guide track. As a function of the direction of rotation of the hub, this movement takes place away from or toward the rotation axis.

According to another variant, the adjustment means can comprise:

- a spool, hinged to the support, preferably at the rotation axis; and

- elongated flexible elements, each connected at one end to the spool and at the opposite end to the mass;

The rotation of the spool, in a closing direction, causes winding of said flexible elements around said spool. The masses, connected to said flexible elements, are thus driven toward the rotation axis. Preferably, opposing elastic means act on the masses in an opposite direction, i.e. away from the rotation axis. When the spool is rotated in an opposite opening direction, the flexible elements are unwound from the spool and the masses are thrust or driven outward by the elastic means, away from the rotation axis.

Also in this variant, the blocking means can act directly on the spool, although it would also be possible to block the masses directly on the support.

The intended objects are also achieved by muscle exercising equipment comprising:

- at least one shaft mounted rotatably about its own axis;

- at least one flexible element constrained to said shaft so as to be wound thereon or unwound therefrom, when it is rotated; and

- at least one flywheel, connected to the shaft, according to any of the variants described above.

The flexible element can be operated by a person, with a limb or with another part of the body, to cause rotation of the shaft and of the flywheel.

The flexible element can be wound directly on the shaft or on a part designated for this purpose and integral in rotation with the shaft.

Further features and advantages of the present invention will become more apparent from the description of an example of a preferred, but not exclusive, embodiment of muscle exercising equipment of isoinertial type, as illustrated in the accompanying figures, wherein:

- Fig. 1 is a perspective view of a flywheel for muscle exercising equipment according to the present invention;

- Fig. 2 is an exploded perspective view of the flywheel of Fig. 1 ;

- Fig. 3 is a rear view of the flywheel of Fig. ;

- Figs. 4a to 4c are front views of the flywheel of Fig. 1 , in different positions of use;

- Fig. 5 is an exploded perspective view of the blocking system the masses;

- Fig. 6 is a sectional view of the flywheel of Fig. 1 provided with the blocking system of Fig. 6;

- Fig. 7 is a front view of the flywheel of Fig. 1 provided with a hub according to another variant of the invention;

- Fig. 8 is an exploded perspective view of the flywheel according to another variant of the invention;

- Fig. 9 is a front view of the flywheel according to a further variant of the invention;

- Fig. 10 is a front view of the flywheel according to a further variant of the invention;

- Fig. 11 is schematic view of a muscle exercising machine on which the flywheel of the present invention is installed.

With reference to the accompanying figures, the numeral 1 indicates a flywheel for muscle exercising equipment.

The accompanying Fig. 11 illustrates, by way of non-limiting example and schematically, an isoinertial machine 100 on which the flywheel 1 according to the present invention is mounted.

This equipment is provided with at least one shaft 101 supported in a frame 102 so as to rotate around its axis Xa.

Preferably, the shaft 101 is supported by rolling means 103 of known type, such as bearings, bushings or the like.

At least a flexible element 104 is constrained by means of a first end thereof to the shaft 101 and can be wound on or unwound from, repeatedly and alternately, said shaft, while performing an exercise.

More precisely, the flexible element 104 can be would directly on the shaft or on a designated part, for example a spool, a pulley or the like, integral in rotation with said shaft 101.

The flexible element 104 can comprise, for example, a rope, a cable, a belt or similar flexible elements. The flexible element 104 can also comprise a bundle of aforesaid elements, more or less close to one another or grouped together.

A connection device 105, schematized in the figure, allows a user to exert a tension force on the flexible element 104, by means of a limb or other part of the body.

Said connection element 105 can be fixed to the opposite end of the flexible element 104, as in the example of Fig. 1 1, or, alternatively, can be mounted slidingly in an intermediate segment of the flexible element 104 by means of pulleys or other sliding means.

Further guides, such as pulleys or the like, can be mounted on the frame 102 to guide the flexible element 103.

The flywheel 1 with the function of inertial mass adapted to accumulate and release kinetic energy is connected to the shaft 101, preferably at one end.

Therefore, the rotation axis X of the flywheel generally coincides with the axis Xa of the shaft 101. However, said axes X, Xa could also be staggered or transverse to each other, for example in the case in which the drive members are interposed between the shaft 101 and the flywheel 1.

Figs. 1 - 4 illustrate the flywheel 1 according to a first embodiment of the invention. The flywheel comprises a support 10, which can be fixed to the shaft 101 of the equipment or to any other rotating part.

The support 10 can have various shapes and can be made of various materials. The support is preferably made of metal, for example steel, aluminum or similar alloys. However, the support can be made of reinforced composite materials, such as fiberglass, carbon or Kevlar.

In the example illustrated, the support 10 is in the shape of a flat plate having a substantially constant thickness. More precisely, the support 10 is substantially in the shape of a cross with a central part 10a destined for fixing to the machine and arms 10b extending outward. A track 1 1 in the shape of a slot, which can pass through the thickness of the support or not, is obtained at each arm 10b.

More generally, the support 10 has a shape such as to have the centroid at the rotation axis X, so as to be balanced when it is rotated.

At least two of the masses 20 are connected to the support 10 with the possibility of moving between a position of minimum distance and a position of maximum distance from the rotation axis X of the flywheel 1. In the example in the figure the flywheel comprises four masses 20, each mounted sliding in a track 1 1.

More precisely, the tracks 11 house a slider 21 sliding along a direction of adjustment R arranged radially with respect to the rotation axis X. At least one mass 20 is fixed to each slider 21. Said slider 21 is maintained in the track by a stop 22 fixed to the slider by means of a screw 23. The aforesaid screw, in the example illustrated, is also used to fix the mass 20 to the slider 21.

As already mentioned, the movement of the masses 20 away from the rotation axis or toward this latter determines a variation of the moment of inertia of the flywheel by virtue of the different distribution of its total mass.

In the example illustrated, the masses 20 comprise blocks in the shape of annular sector. The size, the shape and the number of the masses can vary according to requirements. Preferably, the masses 20 all have the same shape and are all made of the same material. Therefore, the masses 20 generally have the same weight.

Typically, the masses 20 are made of metal or plastic materials.

According to a possible variant, the masses 20 can comprise hollow bodies fillable with a liquid or with another loose solid material, such as sand, metal balls or the like.

The number of the masses 20, just as the number of the tracks 11, can vary. According to the invention, only one mass or more than one mass can slide in the same track.

To ensure that the flywheel is balanced with respect to the rotation axis X, the directions of adjustment R of the various tracks 1 1 are preferably evenly spaced angularly from one another.

For the same purpose, the flywheel is advantageously equipped with adjustment means that allow the masses 20 to be moved in a simultaneous and coordinated manner along the tracks 11. In practice, said adjustment means allow the masses 20, or rather their centroids, to be positioned, optionally maintained, at the same distance from the rotation axis X.

In the example illustrated, the adjustment means comprise a hub 30 rotatably connected to the support 10. More precisely, the hub 30 is hinged to the support 10 at the rotation axis X of the flywheel 1. Even more in detail, the hub 30 is mounted on a spacer 12, positioned at said rotation axis X. The spacer 12 is fixed to the support 10 or alternatively it can be produced in one piece therewith. The function of the spacer 12 is to allow rotation of the hub 30 with respect to the support 10 and to maintain the two parts substantially parallel to each other at a fixed distance.

In the example illustrated, the hub 30 is in shape of a flat sheet having a substantially constant thickness. Drive guides 31, typically in the shape of slots, which can pass through the thickness or not, are obtained in the hub 30.

The hub 30, just as the support 10, can take any shape. Preferably, also the hub 30 has its centroid at the rotation axis X.

Each of said slots is adapted to slidingly house at least one drive pin 24 of each mass 20. Said drive pin 24 can comprise a portion projecting from the block of the mass, made in one piece with or connected to said block, or, as in the example illustrated, it can comprise a portion of the screw 23 for fixing the mass 20 to the support 10. In the variant illustrated in Figs. 1 to 4, the masses 20 are interposed between the support 10 and the hub 30. Therefore, the drive pin is positioned on a side of the block of the mass 20 opposite the side on which the slider 21 is located.

According to the invention, said drive guides 31 engage the drive pins 24 so that, following rotation of the hub 30 with respect to the support, the masses are translated along the tracks 11 toward or away from the rotation axis X, as can be seen in Figs. 4a to 4c. In Fig. 4a the masses 20 are in the position closest to the rotation axis X, corresponding to the configuration of the flywheel 1 with the minimum moment of inertia. On the contrary, in Fig. 4c, the masses 20 are in the position farthest from said rotation axis in a configuration of maximum moment of inertia of the flywheel 1. Between the aforesaid positions of minimum and maximum distance, the masses 20 can be positioned at any intermediate distance, as shown in Fig. 4b, each corresponding to a given moment of inertia of the flywheel 1.

To reduce the friction between the drive pins 24 and the drive guides 31, and therefore the effort to rotate the hub 30, said drive guides 31 preferably have a curved profile. More preferably, the lateral walls 31a, 31b of said drive guides 31 have a curvature with a constant radius.

In the example of Figs. 1 to 4, the hub has a spiral shape with a central portion 30a connected to the spacer 12 and four arms 30b converging toward the rotation axis. The shape of each arm 30b substantially follows that of the drive guides 31. The number of drive guides 31 and of arms 30b can vary as a function of the number of masses 20.

Rotation of the hub 30 with respect to the support 10 can be imparted manually, for example by means of a hand grip 32 or by grasping the hub 30 directly. Alternatively, the hub 30 can be operated by a motor, for example an electric motor.

According to the invention, the flywheel 1 is provided with a blocking device 40 to block the masses 20 on the support 10. As already mentioned, this blocking device is adapted to maintain the position of the masses 20 during use of the equipment, when the flywheel 1 is rotated, in order to maintain the moment of inertia unchanged.

According to a variant of the invention, the blocking device 40 acts directly on the hub 30, preventing rotation thereof with respect to the support 10.

In the example of Figs. 5 and 6, the blocking device 40 comprises a flange 41 mounted sliding on a pin 42 that projects for a segment beyond the hub 30. This pin 42 is connected to an end part of the shaft 101 or, alternatively, is made in one piece with this latter. The flange 41 is provided with at least one coupling tooth 43 adapted to engage respective holes of an array of holes 33 obtained on the hub 30 (Fig. l) to make said flange 41 and said hub 30 integral in rotation. Said holes 33 are arranged in a circular series, the center of which coincides with the rotation axis X. The coupling teeth 43 are preferably at least two.

The pin 42 is housed in a hole 44 of the flange 41. The aforesaid parts have a shape that allows sliding, but not relative rotation, thereof. More in detail, the pin 42 and the hole 44 have a non-circular and at least partially complementary section. The section of the pin and of the hole can substantially be oval, as shown in the example of the figures, provided with keys, ridges or equivalent shapes. In this way, when the coupling teeth 43 are inserted in the holes 33, the shaft 101 can drive in rotation both the support 10 and the flange 41, which in turn engages the hub 30. In this coupling position, the hub 30 is constrained to the rotation with respect to the support 10 and, consequently, the masses 20 are fixed at a given distance from the rotation axis X.

Instead, when the flange 41 is moved away from the hub 30, the coupling teeth 43 exit from the holes 33 completely.

In this free position, the hub 30 can rotate with respect to the support 10 to move the masses 20 away from or toward the rotation axis X.

Sliding of the flange between the coupling position and the free position is controllable by means of a hand grip 48 fixed to the flange 41.

Preferably, a return spring 45, housed in the hand grip 48, thrusts the flange 41 against the hub 30 with a certain force to maintain the coupling teeth 43 stably inserted in the holes 33. Said return spring 45 is interposed between the flange 41 and a stop 46 fixed to the pin 42. A bushing 47, coupled with the flange 41 , acts as positioning element to maintain the spring 45 centered with the axis of the pin 42.

The array of holes 33 allows the hub 30 to be blocked in different coupling positions, each of which corresponding to a value of moment of inertia of the flywheel.

To move the masses 20, and thus vary the aforesaid value of the moment of inertia, it is necessary to pull the hand grip until the coupling teeth 43 disengage from the respective holes 33, rotate the hub 30 with respect to the support until the masses 20 are positioned at the desired distance from the axis and re-engage the coupling teeth in other holes 33 of the array.

The distance between said holes 33 and their number depends on the number of intermediate positions that are required.

Optionally, reference marks (not shown in the figure) can be provided on the hub 30, and in particular on the arms, for the positions of the drive pin 24 to which a given moment of inertia corresponds. In this way, even a person with little experience has a direct and easily intelligible reference for positioning the masses 20.

Fig. 7 illustrates the flywheel 1 in which the hub 30 is provided with a circular band

34, fixed to the arms 30b and which acts as a guard. Said band 34 prevents the arms 30b or the masses 20 from being accidentally bumped by the person using the equipment or by another person in the immediate, especially when the flywheel is in movement.

Said circular band 34 can be connected to the hub 30, for example by means of screws 35, or can be in one piece therewith. The band 34 is rigid and, preferably, is made of the same material as the hub 30.

Fig. 8 illustrates another variant of the flywheel in which the hub 30 has the shape of a cylindrical bell that almost completely surrounds the support 10 and the masses 20. The drive guides 31 and the holes 33 for housing the coupling teeth are obtained on the front face 30' of the hub 30. A lateral edge 36, which extends from the perimeter of the front face 30', surrounds the support 10 and the masses 20. In this variant, each mass 20 comprises two blocks 20a, 20b facing and joined to each other, between which the support 10 is interposed. The variant thus configured is suitable for the use of heavier masses 20 as the symmetrical arrangement of the two blocks prevents, or in any case limits, any deformations of the support 10, which otherwise can occur when the masses are connected on the same side.

In the example in the figure, in place of the four masses, one for each track 1 1 , only one mass 20 is shown, in order to simplify representation.

According to a further variant, according to a diagram similar to the example of Fig. 8, the flywheel can comprise several supports 10 arranged side by side along the rotation axis X between which several arrays of masses 20 are positioned. In this way it is possible to increase. According to this variant, the flywheel can also comprise several hubs 30, optionally interposed between the supports 10, to balance the forces applied to the masses 20 to move them toward or away from the rotation axis.

Fig. 9 is a schematic view of the flywheel 1 according to another embodiment of the invention.

The support 10 and the masses 20 have substantially the same features described for the other variants. According to a first simpler embodiment, the masses 20 can slide along the tracks 11 of the support toward or away from the rotation axis X. Positioning is carried out manually, moving the mass 20 to the selected distance. Also, in this case reference marks can be provided on the support 10 to facilitate this operation and to ensure that all the masses 20 are at the same distance from the rotation axis X. Blocking of the masses 20 can take place with clamps, screw means or the like. Preferably, each mass 20 is connected to an elastic element 37 that acts thereon to move it toward or alternatively away from the rotation axis X.

According to another embodiment, illustrated in Fig. 9, the flywheel also comprises adjustment means of the position of the masses 20. Said adjustment means comprise a spool 50, hinged to the support 10, and cables 51, ropes or similar flexible elements, connected at one end to the spool 50 and at an opposite end to the mass 20.

Rotation of the spool 50, in a closing direction, causes winding of the cables 51 on said spool. The masses 20 connected thereto are thus driven toward the rotation axis X. The elastic elements 37 exert a return action on the masses 20 in the opposite direction with respect to that of the cables, i.e., away from the rotation axis.

When the spool 50 is rotated in an opposite opening direction, the cables 51 are unwound from the spool 50 and the masses 20 are carried outward by the elastic elements 37, away from the rotation axis X.

In another variant of the invention, not illustrated in the figures, the adjustment means can comprise a hub, rotating around the rotation axis X, connected to rods hinged to the masses. Rotation of the hub causes the movement of the rods and thus of the masses along the adjustment direction.

Fig. 10 illustrates another variant of the flywheel according to the invention.

In this variant, the masses 20 are connected to the support 10 by means of joints 25 that allow rotation around an axis Xm. Said joints can be hinges, pin/hole couplings or the like.

The position of the axis Xm is such as to allow movement of the centroid of the mass 20 following its rotation.

The axis Xm can be substantially parallel to the rotation axis X of the flywheel, as in the example in the figure, or transverse or perpendicular thereto.

Adjustment of the position of the masses 20 can take place manually or by means of an adjustment system selected from those described above. In this case, the mass 20, rotating around the axis Xm, carries its centroid closer to or farther from the rotation axis X, varying the moment of inertia of the flywheel.

The invention has been described purely for illustrative and non-limiting purposes, according to some preferred embodiments. Those skilled in the art may find numerous other embodiments and variants, all falling within the scope of protection of the claims below.