The invention can be applied particularly but not exclusively to bicycles or similar non-motorized vehicles.

Background Art Bicycle dynamos have now been known for many years.

The term"dynamo"is misleading, since these current generators for bicycles or the like are alternators.

Hereinafter, this type of current generator is therefore referenced with the term"dynamo-alternator".

These dynamo-alternators are composed of an electric generator constituted by a frame inside which electrical windings are arranged (on a corresponding stator, which is implicitly formed together with the windings and is typically provided on the frame) and by a rotor with pole shoes.

A roller arranged outside the frame is keyed to the rotation shaft of the rotor and transmits motion to the rotor by mechanical friction with the tire (or rim) of the wheel of the vehicle to which it is applied.

Dynamo-alternators of this kind, although having been used for many years, have several problems and drawbacks.

A first drawback is the limited efficiency of the conversion of the mechanical energy drawn at the wheel into electric power transformed inside the generator ; this limited efficiency depends on the many energy losses that occur already upon contact between the roller of the dynamo- alternator and the wheel. These losses can be summarized for example as losses due to non-optimum friction, heat dissipation,"noise"generation (acoustic dissipation), etcetera.

Other losses can be found in the mechanisms for the rotation of the assembly constituted by the roller and the rotor.

Further, taking into account the relative wear of the roller and the wheel, and that these components are generally not subjected to maintenance, the overall efficiency of the dynamo-alternator deteriorates over time, further reducing the already poor conversion of mechanical energy into electric power.

Another problem linked to the conventional dynamo-alternator is the strict dependency between the angular velocity of the wheel of the vehicle and the voltage generated by such dynamo-alternator : in practice, a voltage suitable to conveniently supply power for example to user devices such as front and rear lights is available only at high wheel velocities.

In this regard, it should be noted that wheel conditions may cause well-known and unpleasant variations in the emitted luminous flux, in practice an inconstant lighting of the road surface on which one is traveling.

This also occurs in the case of a wet or dirty wheel or due to simple mechanical wear of the motion transmission elements.

Another drawback linked to current dynamo-alternators can be ascribed to the abrasion that the external roller produces on the wheel on which it grips (by friction), causing deterioration thereof.

In view of the roller-tire coupling, moreover, the unpleasant noise generated by the roller in contact with the tire is well-known; this noise, as mentioned, indicates a dissipation of energy in acoustic form.

Another significant drawback is that in order to achieve the actuation of the dynamo-actuator it is necessary to act mechanically on the snap- acting device that releases the dynamo-alternator from the inactive position so as to make engage the wheel and draw motion from it.

This snap-acting device is often dirty and located in a very awkward position.

Another drawback linked to current dynamo-alternators is that the electric power supply in practice ceases when motion ceases, thus exposing the user to situations of real danger when he/she stops, for example at a

traffic light or at an intersection, especially if it is not lit, or on the roadside before turning or for any other reason for which one is forced to stop temporarily in dangerous situations.

Disclosure of the Invention The aim of the present invention is to provide an electric current generator for vehicles that solves the problems and drawbacks noted in known types.

Within this aim, an object of the present invention is to provide an electric current generator for vehicles that allows to improve the efficiency of the conversion from mechanical energy to electric power with respect to the conversion obtained in known devices.

Another object of the present invention is to provide an electric current generator for vehicles that allows to avoid unpleasant noise caused by friction and imperfections of the roller-wheel coupling that occur in known devices.

Another object of the present invention is to provide an electric current generator for vehicles that avoids the need to operate mechanisms in order to activate the generator.

Another object of the present invention is to provide an electric current generator for vehicles that allows to supply power to electrical user devices even when the vehicle is stationary.

Another object of the present invention is to provide an electric current generator for vehicles that can be manufactured with known systems and technologies.

This aim and these and other objects that will become better apparent hereinafter are achieved by an electric current generator for vehicles, comprising a dynamo-alternator to be fixed to the frame of the vehicle at one of its wheels, characterized in that it comprises a rotor body that is coaxial to the electrical windings of said dynamo-alternator and is functionally associated with them, said rotor body being spaced from said

wheel and having, coaxially to its rotation axis, a first circular series of driven elements, which interacts by magnetic attraction with a complementary second circular series of driving elements arranged on said wheel coaxially thereto, at least one of said series of elements being constituted by mutually alternated magnetic poles of opposite signs, said second series of driving elements causing, during the movement of the vehicle, the tangential rotary entrainment, by magnetic attraction, of said first series of driven elements.

Brief Description of the Drawings Further characteristics and advantages of the invention will become better apparent from the following detailed description of some preferred but not exclusive embodiments thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein: Figure 1 is a view of a bicycle on which a device according to the invention is fitted; Figure 2 is a schematic sectional view of a first embodiment of a device according to the invention; Figure 3 is a schematic perspective view of a second embodiment of a device according to the invention; Figure 4 is a schematic perspective view of a third embodiment of a device according to the invention; Figure 5 is a schematic perspective view of a fourth embodiment of a device according to the invention; Figure 6 is a basic electrical diagram of a device according to the invention; Figure 7 is a schematic sectional view of an alternative embodiment of the dynamo-alternator of a device according to the invention; Figure 8 is a schematic sectional view of another alternative embodiment of the dynamo-alternator of a device according to the invention;

Figure 9 is a perspective view of a portion of a wheel with part of a device according to the invention; Figure 10 is a perspective view of another portion of a wheel with part of a device according to the invention.

Ways of carrying out the Invention With reference to Figures 1 and 2, a first embodiment of an electric current generator according to the invention is generally designated by the reference numeral 10.

The device 10 is applied to a vehicle 11, such as for example a bicycle, and comprises a dynamo-alternator 12 (substantially, an alternator is intended), to be fixed to the frame of the vehicle l l at one of its wheels 13, such as for example the front wheel.

The dynamo-alternator 12 is composed of a frame 14, inside which electrical windings 15, rigidly coupled to a stator body 15a (shown in the figures together with the windings 15), and a rotor body 16 are arranged.

In this first embodiment, the rotor body 16 is substantially composed of two components: an internal rotor 17, which is provided with magnetic pole shoes 18, and an external rotor 19, which is keyed on the same rotation axis 20 as the internal rotor 17.

The external rotor 19 has, coaxially to its rotation axis, a first circular series of driven elements 21, which in this embodiment are constituted by first mutually alternated magnetic poles 22 of opposite signs.

The first circular series of driven elenaents 21 interacts by magnetic attraction with a complementary second circular series of driving elements 23, which is arranged on the wheel 13 of the vehicle 11 coaxially to the rotation axis of the wheel 13.

The driving elements 23 are constituted, in this embodiment, by second mutually alternated magnetic poles 24 of opposite signs.

For example, the second circular series of driving elements 23 is embedded within the outer edge 25 (directed toward the side with the

dynamo-alternator 12) of the rim 26 of the : wheel 13, so as to avoid compromising the braking surface for the brake pads of the bicycle (not shown in the figures).

The operation of the generator according to the invention is simple.

The movement of the vehicle 11 turns the wheel 13 and accordingly the driving elements 23 rotate rigidly with it.

The spacing between the driven elements 21 and between the driving elements 23, as well as their distance, are such that the second series of driving elements 23 produces the tangential rotary engagement, by way of the magnetic attraction force, of the first series of elements 21.

Accordingly, the internal rotor 17 is turned without any direct contact of the dynamo-alternator with the wheel 13, producing electric power.

Electric power supply cables 12a for user devices 12b, such as for example lighting devices, extend from the dynatno-alternator 12.

With reference to Figure 3, a device according to a second embodiment is now designated by the reference numeral 100.

The device 100 comprises a dynamo-alte-rnator 112 to be fixed to the frame of the vehicle, not shown here, at one of its wheels (also not shown).

The difference with respect to the first described embodiment relates substantially to the dynamo-alternator 112.

The dynamo-alternator 112 is composed of a frame 114, inside which there are electrical windings 115, rigidly coupled to a stator body 115a (shown together with the windings 115 in the figures), and a rotor body 116.

In this second embodiment, the rotor body 116 is substantially composed of a single internal rotor 117, which is provided with a first circular series of driven elements 121, which coincide with the pole shoes suitable to induce currents, by way of their rotation, on the electrical windings 115.

The driven elements 121 are therefore constituted by first mutually alternated magnetic poles 122 of opposite signs.

The first circular series of driven elements 121 is arranged substantially in front of the second circular series of driving elements 123, which in Figure 3 has been shown schematically, for the sake of greater clarity, without the wheel of the vehicle.

In this second embodiment also, the driving elements 123 are constituted by second mutually alternated magnetic poles 124 of opposite signs.

The frame 114 has, in front of the second circular series of driving elements 123, a window 130 for"magnetic match-up"between the driving elements 123 and the driven elements 121.

Conveniently, the window 130 is closed with nonmagnetic material, such as to not interfere with the magnetic attraction force, such as for example plastics.

In practice, in this second embodiment the internal rotor 116 acts simultaneously as a"driven wheel"in the magnetic coupling with the second circular series of driving elements 123 and as an inductor for inducing current on the windings 115.

It is evident that in order to produce the tangential rotary entrainment of the rotor body 16-116 it is not necessary for the first circular series of driven elements 21-121 and for the second circular series of driving elements 23-123 to be both composed of magnetic poles.

It is in fact enough for just one of the two circular series of elements (driving or driven ones) to be formed by magnetic poles, and it is enough for the other one to have pole shoes made of a ferromagnetic material or of a material that becomes magnetized if subjected to a magnetic field.

In this regard, with reference to Figure 4, a third embodiment of the device according to the invention is generally designated by the reference numeral 200.

As in the first embodiment, the dynamo-alternator 212 is composed of a frame 214, inside which there are electrical windings, a stator body (these

last two are not shown), and a rotor body 216.

The rotor body 216 is substantially composed of an internal rotor 217, which is provided with magnetic pole shoes 218, and of art external rotor 219, which is keyed on the same rotation shaft (not shown) as the internal rotor 217.

The external rotor 219 has, coaxially to its own rotation axis, a first circular series of driven elements 221, which are constituted by first mutually alternated magnetic poles 222 of opposite signs.

Said first circular series of driven elements 221 interacts by magnetic attraction with a complementary second circular series of driving elements 223, which is arranged on the wheel 213 of the vehicle (which is not designated by a reference numeral) to which the device 200 is applied coaxially to the rotation axis of the wheel 213.

The driving elements 223 are constituted, in this third embodiment, by protrusions 224 made of a material that is ferromagnetic or such as to be attracted magnetically when it is immersed in a magnetic field-.

For example, the second circular series of driving elements 223 is embedded within the outer edge 225 (facing the side with the dynamo- alternator 212) of the rim 226 of the wheel 223, so as to not compromise the braking surface for the pads of the brakes of the bicycle ("which are not shown in the figures).

With reference to Figure 5, a fourth embodiment of a device according to the invention, now designated by the reference numeral 300, comprises a dynamo-alternator 312 to be fixed to the frame of the vehicle, not shown here, at one of its wheels (also not shown).

The difference with respect to the first and second described embodiments 10 and 100 relates substantially to the dynamo-lternator 312.

The dynamo-alternator 312 is composed of a frame 314-, inside which the electrical windings, a stator body (both not shown), and a rotor body 316 are arranged.

The rotor body 316, in this fourth embodiment, is substantially composed of two components: an internal rotor 317, which is provided with magnetic pole shoes 318, and an external rotor 319, which is keyed on the same rotation shaft (not shown) as the internal rotor 317.

The external rotor 319 has, coaxially to its own rotation axis, a first circular series of driven elements 321, which in this embodiment are constituted by protrusions 322 made of a material that is ferromagnetic or otherwise such as to be attracted magnetically when it is immersed in a magnetic field.

The first circular series of driven elements 321 interacts by magnetic attraction with a complementary second circular series of driving elements 323, which is provided on the wheel of the bicycle as in the other described embodiments.

In this case, the driving elements 323 must be mutually alternated magnetic poles 324 of opposite signs, so as to rotationally attract the first series of driven elements 321.

Figure 6 illustrates a basic electrical diagram of a device according to the invention.

The diagram illustrates a generator 31 (the dynamo-alternator with optional current rectifying section), which is connected electrically to an electrical storage section 32, which in turn is connected electrically to the user devices 12b.

The user devices 12b comprise the lighting devices 33 (a front one and a rear one), lighting sensors 34 suitable to detect the amount of ambient light, and an electronic board 35 for management of the electric current and of the various signals.

By way of the storage section 32, the user devices can operate even when the vehicle is not moving.

Further, the lighting devices 33 can be activated when the lighting sensors 34 determine that the available light is insufficient.

Figure 7 illustrates an alternative embodiment of the dynamo- alternator, now generally designated by the reference numeral 412_ In this case, the stator body 415a is constituted by a first magnetic stator element 440 and by a second magnetic stator element 441 that is coaxial thereto, both being obviously accommodated within the frame 414.

The rotor body 416 is arranged between the first and second magnetic stator elements 440 and 441.

The rotor body 416 substantially comprises an internal rotor 417, which is keyed on a rotation shaft 420, and an external rotor 419, of the type described in the previous examples, which is keyed on the sane rotation shaft 420 as the internal rotor 417.

The internal rotor 417 is made of magnetically neutral material, and the electrical windings 415 are fixed on to it.

Another embodiment of the dynamo-alternator, generally designated by the reference numeral 512, is shown in Figure 8.

In this case, the rotor body 516 substantially comprises am internal rotor 517, which is keyed on a rotation shaft 520, and an external rotor 519, of the type described in the previous examples, which is keyed os the same rotation shaft 520 as the internal rotor 517.

The internal rotor 517 is constituted by a first magnetic rotor element 540, which is rigidly coupled coaxially to a second magnetic roto element 541.

The stator body 515a is arranged between the first and second magnetic rotor elements 540 and 541 and is fixed with respect to the frame 514; the electrical windings 515 are fixed on to the frame.

The stator body 515a is made of a magnetically neutral material, such as for example plastics.

In the embodiment of Figure 7 and in the embodiment of Figure 8, a relative rotation of the electrical windings (which are rigidly coupled to a magnetically neutral support) occurs with respect to the elements that

generate the magnetic field.

Advantageously, this allows to eliminate the armature feedback (electric power that contrasts the rotary motion of the rotor body) of the mutually rotating magnetic materials that occurs when the electrical windings are closed across the user devices, to the full benefit of the overall efficiency of the device and of the power expended during the pedaLing stroke by the cyclist.

It is evident that a dynamo-alternator such as the one described-in Figures 7 and 8 is independent of the concept of magnetic attraction between driving elements and driven elements arranged on the wheel and on the dynamo, since it can be advantageously applied also to other types of dynamo-alternator, such as for example the traditional type, achieving the same advantages of reduction of the forces to be overcome.

Figure 9 shows a different embodiment of the wheel, now designated by the reference numeral 613.

In this embodiment, the second circular series of driving elements 623 is integrated on the tire 613 a of the wheel 613.

In particular, the second circular series of driving elements 623 is integrated on the tread 613b of the tire of the wheel 613.

Likewise, with reference to Figure 10, the second circular series of driving elements 723 is integrated on the side 713b of the tire 713a of the wheel 713.

The ways of integrating the second circular series of driving elements on the tire may be the most disparate, such as for example co-molding a-nd direct application by adhesive bonding.

In practice it has been found that the invention thus described solves the problems noted in known types of electric generator.

The present invention in fact relates to a dynamo-alternator that requires no mechanical power take-off.

The rotary motion is imparted to the rotor body by way of a magnetic

coupling, thus optimizing the efficiency of conversion between mechanical energy and electric power.

Further, the fact of structuring the dynamo-alternator so as to provide a relative rotation of the electrical windings (which are rigidly coupled to a magnetically neutral support) with respect to the elements that generate the magnetic field has allowed to eliminate the armature feedback of the mutually turning magnetic materials that occurs when the electrical windings are closed across the user devices, to the full benefit of the overall efficiency of the device and of the power expended in the pedaling stroke by the cyclist.

The fact that no windings on materials that are ferromagnetic or otherwise magnetizable if subjected to magnetic fields are provided allows (in this type of embodiment) to avoid allocating power in order to overcome the attraction forces between the magnets and the ferromagnetic system, typically the rotor and the stator in conventional dynamo-alternators, and, by increasing the rotation rate, also the various losses in iron caused mainly by a Joule effect due to induced currents. Such power levels are in any case required even without an electrical load applied by conventional dynamo- alternators.

The fact that the device does not require direct contact with the wheel avoids the need to activate any snap-acting mechanism in order to activate the dynamo-alternator.

The rotor body of the dynamo-alternator is always rotating when the vehicle is moving, even when the user devices are not activated.

By way of this characteristic, by associating an electric power storage section it is possible to utilize said electric power when the vehicle is not moving.

The use of lighting sensors allows to avoid operating any control to activate the lighting devices.

The invention thus conceived is susceptible of numerous

modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements.

In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art.

The disclosures in Italian Patent Application No. PD2004A000032 from which this application claims priority are incorporated herein by reference.