D E S C R I P T I O N

Field of application

The present invention is applicable to the vehicle field and, in particular, relates to a hybrid or electric vehicle.

More in detail, the present invention relates to the gears, which couple an electric machine to the driving wheels of a vehicle.

Background art

Among light or hybrid electric vehicles, those with one or more wheels and pedal assisted vehicles are known. A well known, however particular example, are the pedal assisted bicycles, which are becoming increasingly common in daily use. Other known electric vehicles are those provided with one or more electrically driven motor wheels in which the hybrid functionality induced by pedalling may also be present, exploiting known typically chain-driven secondary transmission devices or a serial hybrid.

Such vehicles often use fast, small-diameter electric machines that assist the user in pedalling effort. However, these electric machines are coupled with the vehicle movement section by gears and simple gear trains, which allow increasing the torque by reducing the speed so as to be able to modify the power produced by the electric machine and ensure at least the minimum standards necessary for the movement of the vehicle.

These gears therefore act as speed reducers.

In some cases, the electric machine is directly inserted into a wheel, which is then called a motor wheel. Typically, a kinematic chain is present therein, which is developed around a central axis composed of an outer wheel with internal teeth. The latter, in the most used configuration, meshes with three external toothed wheels arranged with an identical angular distance between three parallel axes along a concentric circumference with a smaller diameter. In turn, these three wheels mesh with an external toothed wheel arranged on the central axis. Between the driving wheel of the vehicle and the electric machine, in order to privilege the agility of driving, a free wheel typically acts that prevents the transfer of the kinetic power of the vehicle to the electric machine, preventing its exploitation as a generator.

Although this kinematic chain is at least aesthetically similar to an epicyclic gear train, it is an ordinary gear because the axes of the wheels engaged are fixed in space. Substantially, therefore, these kinematic chains do not exploit the peculiarities of the epicyclic gear trains, since the structure called train carrier or planet carrier does not rotate around the planets. These gear trains, however, are used as reducers, but due to the limits imposed by the radial dimension, they have a reduction ratio which is nevertheless low, which can only be increased by using several stages of reduction.

They, moreover, are particularly expensive, especially due to the presence of the outer wheel with internal teeth.

Vehicles are also known in which the electric machine is an integral part of the bottom bracket. However, even in this case, the kinematic chains used to couple the electric machine to the vehicle driving section are traditional transmissions, gears or simple gear trains. They are usually configured with two or three stages of reducing the speed of the electric machine and consisted of gears located on two or three parallel fixed axes.

It follows that they have the same drawbacks as described above, that is, they do not allow the electric machine to be used as a power generator and do not allow to obtain high reduction ratios with a single stage.

Also in this case, therefore, not only the kinematic chains are cumbersome and expensive, but they also require the use of specific electrical machines without freedom of choice for the manufacturer. It follows that the choice of the electric machine is typically not optimal both in terms of dimensions and power, as well as of quality of the same.

Two-speed multi-gear motor wheels are also known. For the execution of the two speeds they use also simple gear trains and the second speed is obtained by inverting the rotation direction of the electric machine. It follows that not only is it possible to achieve neither more than two gears nor a reverse gear, but the use of the electric machine as a power generator is also prevented, even if desired. Presentation of the invention

The object of the present invention is at least partially overcoming the above-noted drawbacks by providing a vehicle with one or more driving wheels whose kinematic chain connecting the electric machine with the vehicle movement section is less expensive than the known equivalent vehicles.

Another object is that the kinematic chain of the vehicle of the invention allows reduction and multiplication transmission ratios higher than in the known equivalent vehicles.

A further object is that such reduction or multiplication transmission ratios are obtained with a single stage.

Another object is that the kinematic chain of the vehicle of the invention allows to use the electric machine also for the generation of power.

A further object is that the kinematic chain of the vehicle of the invention has, at the same reduction ratio, a smaller size than what happens in the known equivalent vehicles.

Another object is that the kinematic chain of the vehicle of the invention allows to realize a multi-gear transmission with a number of gears greater than two.

In particular, a further object is that the vehicle of the invention allows reversing the motion, that is, it allows the realization of the reverse gear.

Said objects, as well as others which will become clearer below, are achieved by a vehicle with one or more driving wheels according to the following claims, which are to be considered as an integral part of this patent.

In particular, it comprises at least one electric machine, typically but not necessarily of the torque and external rotor type, operatively coupled with an epicycloidal gear train with exclusively external gear teeth. In turn, the latter comprises a fixed planet gear coupled with the vehicle structure and a planet train carrier structure rotating according to a first axis of rotation and coupled with the rotor of the electric machine. This rotor, of course, is rotatable according to a second axis of rotation.

There are also one or more satellite trains rotatably coupled with the train carrier structure. The epicycloidal gear train also comprises at least one rotating moving planet according to a third axis of rotation, which is common to the aforementioned first and second rotation axes.

In other words, in the epicycloidal gear train of the vehicle of the invention the rotor of the electric machine, the train carrier structure and the moving planet rotate according to a common axis.

From the above, advantageously, the epicycloidal gear train is devoid of gears with internal teeth (in particular the sprocket with internal teeth), which are, as is known, the most expensive elements of the gear train. Moreover, they are also cumbersome and difficult to apply for problems of centering, precision and sealing, especially if they are provided in rotation and/or for high transmission ratios.

It follows, advantageously, that the epicycloidal gear train of the vehicle of the invention is not only less expensive in terms of execution costs, but is also simpler to perform and to assemble, less cumbersome, and more resistant over time.

Still advantageously, the improved compactness of the epicycloidal gear train thus carried out allows a greater choice of the transmission ratio, both in reduction and in multiplication, while having the same overall radial dimensions.

This gear train, however, allows a strong economy of scale because it is possible to easily vary the reduction ratio.

This gear train, moreover, allows a strong economy of scale thanks to the plurality of applications that can be realized, since it is possible to easily change its transmission reduction ratio by keeping the same number and type of toothed wheels that compose it. In other words, its flexibility also allows to easily adapt the result obtainable to the needs in terms of torque at the same power without increasing costs and complexity of execution.

Still advantageously, such a gear train allows the attainment of several gears simply by adding moving planets and planets to the planet trains. However, there is no limit to the number of gears, with the maximum limit imposed exclusively by the overall dimension to impose. This, again advantageously, allows the economization of scale of the vehicle of the invention to be even more improved.

Still advantageously, however, in the vehicle of the invention it is possible to invert the sense of rotation between the inlet and outlet of the epicycloidal gear train with the same number of gears. In other words, advantageously, in the vehicle of the invention the electric machine can be used, unlike in the prior art, also for the generation of power.

Brief Description of the Drawings

Further features and advantages of the invention will become more evident in light of the detailed description of a preferred but not exclusive embodiment of a vehicle with one or more driving wheels according to the invention, illustrated by way of non-limiting example with the aid of the accompanying drawings, wherein:

FIG. 1 is a front view of a vehicle according to the invention; FIGS. 2 to 4 represent some details of the vehicle of FIG. 1 ; - FIGS. 5 and 6 show details of a first variant embodiment of the vehicle of FIG. 1 ;

FIG. 7 represents a detail of a second variant embodiment of the vehicle of FIG. 1 ;

FIGS. 8 and 9 show some details of a third variant embodiment of the vehicle of FIG. 1 .

Detailed description of some preferred embodiment example With reference to the above mentioned figures, and in particular to Fig. 1 , described herein is a vehicle with one or more driving wheels 1. The figure shows a pedal assisted bicycle, but this should not be considered as limiting for the invention. In fact, the present invention relates to any vehicle without excluding, for example, agricultural machinery driven by motor wheels, mopeds, or the like.

According to the embodiment described, the vehicle 1 comprises a pair of pedal cranks with pedals 2 acting on a bottom bracket 3.

The vehicle 1 is provided with a driving wheel 5, which is constituted by the rear wheel of the bicycle. Also this aspect, however, must not be considered limiting for different embodiments of the invention according to which the driving wheel is the front wheel or according to which there are several driving wheels.

The same vehicle 1 also includes an electric machine 6. According to the embodiment described, it is of a torque and an external rotor type, but this detail must not be considered as limiting for the invention. It is operatively operative with the bottom bracket 3 to assist the action performed by the pedals 2. Previously, in fact, it has been said that the pedal assisted vehicle described is only a possible embodiment of the invention. In particular, it should be noted that some variant embodiments envisage the presence of only the electric machine for moving the vehicle. In other words, although the vehicle described is a hybrid vehicle with electric and muscular power sources, the present invention also relates to hybrid vehicles with different sources and to only electric vehicles.

In the embodiment described, the electric machine 6 assists pedalling by acting in the form of a drive roller with direct contact to the wheel 5. However, as we will see later, this should not be considered as limiting for the invention, the electric machine being able to be positioned on the wheel (motor wheel) or in another position and associated with the wheel and the pedals by means of specific mechanical transmissions. Also the number of present electric machines should not be considered limiting for the invention, as it could be any possible number.

According to an aspect of the invention, as can be seen in detail in Figs. 2 and 3, between the pedals 2 and the electric machine 6 an epicyclic gear train 8 is operatively interposed.

In particular, this epicyclic gear train 8 first comprises a fixed planet gear 10. It is kept fixed by associating it with the structure 11 of the vehicle 1. In the case of the figures, the structure 11 is the bicycle frame.

Then there is a moving planet 12 (in particular of the rotating type) coupled with the pedals 2 for its movement. This coupling, as shown in the figures, is achieved by means of a free-wheel device 14 whose usefulness will be analysed below.

According to another aspect of the invention, the epicycloidal gear train 8 also comprises a train carrier structure 15 coupled with the electric machine 6. To this train carrier structure 15 satellite trains 16 are rotatably coupled.

In particular, the train carrier structure 15 is integral with the rotor 18 of the electric machine 6, while the stator 19 is integral with the fixed planet gear 10 and with the train carrier structure 11. The satellites 16 are two pairs and are coupled integrally with each other, but also this detail, as will be better seen later, should not be considered as limiting for the invention.

According to a further aspect of the invention, the train carrier structure 15 is rotatable according to a first axis of rotation X, the rotor 18 of the electric machine 6 is rotatable according to a second axis of rotation Y coinciding with the first axis of rotation X, and the moving planet 12 is rotatable according to a third axis of rotation Z coinciding with the first X and the second axis of rotation Y. In other words, the three axes of rotation X, Y and Z are common.

Advantageously, the fact of having the axes of rotation in common considerably simplifies, also reducing its dimensions, the mechanical structure of the electric machine 6 - epicycloidal gear train 8 pair.

Still advantageously, it can be observed that the epicycloidal gear train 8 is devoid of gears with internal teeth (i.e., the sprocket with internal teeth). Since the gear with internal gear teeth is, as is known, the most expensive component of the gear train, it is evident that this fact is above all a factor of economic savings.

Moreover, since the gear with internal gear teeth is typically the most bulky, this makes it possible to reduce the overall dimensions of the epicycloidal gear train 8.

Moreover, during assembly, the gear with internal teeth is difficult to apply for problems of centering, precision and sealing, especially when it is designed for rotation and/or for high transmission ratios. All this is therefore advantageously avoided with the epicyclic gear train 8 used in the vehicle 1 of the invention.

From all this it follows, still advantageously, that the epicycloidal gear train 8 of the vehicle 1 of the invention is not only less expensive in terms of execution costs, but is also simpler to perform and to assemble, less cumbersome, and more resistant over time. The improved compactness of the epicycloidal gear train 8 thus carried out allows, in addition, a greater possibility of choice of the transmission ratio, both in reduction and in multiplication, with the same overall radial dimensions. This means that it is easily adaptable to the specific needs of the vehicle 1 to which it is applied, and also allows a strong economy of scale.

Still advantageously, the epicyclic gear train 8 thus realized allows to maintain the possibility of inverting the direction of rotation between input and output with the same number of gears. In other words, advantageously, in the vehicle 1 of the invention the electric machine 6 can be used, unlike in the prior art, also for the generation of power.

From the foregoing it can be inferred that one aspect of the present invention is that epicycloidal gear train 8 is configured with exclusively external gear wheels, which allows to obtain very high transmission ratios, even with a single stage, unlike the ordinary gears of the prior art.

Moreover, still advantageously, it is observed that in the vehicle 1 of the invention, thanks to the use of the epicycloidal gear train 8 to connect the drive section with the pedals 2 and the electric machine 6, secondary mechanical transmissions with shaft, belt or chain can be absent at all.

As regards the pair of satellites 16, it is observed that a first satellite 20 meshes with the fixed planet gear 10, while the second satellite 21 meshes with the moving planet 12. In the same figures, it is observed that the two satellites 20, 21 have different diameters, and therefore are distinguished by the number of external teeth, although they rotate with the same angular speed, since they are integral with each other.

Operatively, therefore, the mechanical power produced by the pedals 2 is provided through the free-wheel device 14 to the epicyclic gear train 8. The train carrier structure 15 is the component in which the hybrid combination of this power occurs with the additional power supplied by the electric machine 6. This power is transmitted by friction to the wheel 5 by the rotor 18.

When the angular speed induced by the pedalling exceeds that induced by the electric machine 6, a transfer of power on the wheel 5, and therefore the movement of the vehicle 1 occur, as a result of the pedalling-only mode. When the angular speed induced by the electric machine 6 exceeds that induced by the pedalling, a transfer of power on the wheel 5, and therefore the movement of the vehicle 1 occur, as a result of the motorized mode.

It is evident that a suitable transducer and electronic management system (or the sensitivity in the user pedalling) also allows to realize the hybrid operating mode, which occurs by controlling the speed of the electric machine 6 to equal that of the pedal stroke, or vice versa. In other words, the pedalling frequency is conveniently multiplied by the epicyclic gear train 8 so as to make the sum of the powers from electrical and muscle sources available to the wheel 5 of the vehicle 1.

Previously it has been mentioned that the vehicle 1 also allows the operating mode corresponding to power recovery or regeneration. It is achieved by controlling the electric machine 6 in an electric generator mode capable of transforming the kinetic power of the moving vehicle 1 into electrical power useful for charging the electric charge accumulator or for other uses. This peculiarity is ensured by the combined use of the epicycloidal gear train 8 with the electric machine 6 and a free wheel acting between the bottom bracket 3 and the moving planet 12.

In the configuration described, also shown in FIG. 4, the vehicle 1 has its driving wheel 5 moved with the drive roller system, i.e. the wheel 5 is arranged in contact with the rotor 18 of the electric machine 6 so that the latter rotates to rotate it. This is equivalent to saying that the wheel 5 is coupled with the train carrier structure 8.

However, such an embodiment should not be considered as limiting for different variant embodiments.

A first of them is shown in FIGS. 5 and 6, where the epicyclic gear train 108 and the electric machine 106 still reside in the bottom bracket 103, but the connection to the driving wheel 105 occurs through a special mechanical transmission 130, which, in its more classic version, comprises a chain 131 meshing on a traction pulley 132 belonging to the bottom bracket 103 (and therefore associated with the rotor 118 of the electric machine 106) and on a driven pulley 133 stably coupled with the driving wheel 105. However, also the positioning of gear train and electric machine in the bottom bracket is a feature that should not be considered limiting for the invention.

In the variant embodiment of Fig. 7, for example, they are arranged in a suitable housing 240 belonging to the driving wheel 205. A motor wheel is therefore shown in the figure.

In this case, it is observed that the moving planet 212 is integral with the hub 241 of the wheel 205 and the fixed planet gear 210 is integral with the fixing pin 242 of the wheel 205 itself.

The absence, as no longer necessary, of the free-wheel device is also observed.

Advantageously, the motor vehicle just described makes it possible to realize not only hybrid vehicles such as the bicycle described herein above, but also exclusively electric vehicles. The driving wheel 205 of FIG. 7, in fact, can move any vehicle independently of the presence not only of pedals, but in general of a second driving force.

Advantageously, therefore, the driving wheel 205 is used, according to some embodiments, for the execution of vehicles such as scooters, agricultural machines, electric motorcycles or the like, all of which are within the scope of protection of the present invention.

Moreover, according to a particular variant embodiment, not shown in the figures, the vehicle of the invention comprises a motor wheel, such as that just described, and a further electric machine coupled with an epicyclic gear train, such as that just described, to a pair of pedals for generating electrical power that powers the motor wheel, so as to define a so-called "serial hybrid". In other words, in the context of protection of the present patent, vehicles involving the use of one or more motor wheels are also included, such as the only electrically powered motor wheel above described, and electric machines specifically moved to generate electric power that powers the motor wheels, directly or through an electric accumulator.

The "motor wheel" type configuration just described allows, advantageously, to realize even more gears (including variant embodiments having reverse gear and/or neutral position with power recovery possibility). In this sense, the variant embodiment represented in Figs. 8 and 9 show the addition of a further moving planet 350 integrally coupled with the train carrier structure 315. In addition to this, there is a selector 351 which selectively couples the moving planet 312 or the further moving planet 350 to the hub 341 of the wheel 305. Since the moving planet 312 is coupled with the second satellite 321 , while the further moving planet 350 is coupled with the train carrier structure 315, it is evident that they rotate at different speeds, i.e. that the reduction ratio which distinguishes them is different. In particular, the moving planet 312 performs a reduced gear, while the further moving planet 350 achieves a direct grip.

Advantageously, therefore, two different gears have been obtained without substantially increasing the overall dimensions and without using the inversion of rotation of the electric machine, which can still be dedicated to the regeneration of electrical power thanks to the absence of free wheels or other locking mechanisms.

Still advantageously, it is possible to obtain variant embodiments with more than two gears. In fact, it will be sufficient to add further moving planets and other satellites to the satellite trains, obtaining different reduction ratios with a limited increase in overall dimensions.

In light of the foregoing, it is understood that the pedal assisted vehicle of the invention achieves all the prefixed purposes.

In particular, the kinematic chain connecting the electric machine with the vehicle movement section is less expensive than the known equivalent vehicles, at least for the absence of gears with internal teeth.

The kinematic chain of the vehicle of the invention allows reduction ratios higher than in equivalent known vehicles, thanks to the use of an epicyclic gear train, which also allows to keep low the overall dimensions. It also allows, for the same reason, a wider choice of electric machines to be used.

Moreover, the kinematic chain of the vehicle of the invention allows to use the electric machine also for the generation of power while allowing the realization of a multi-gear version, however, also with more than two gears. The invention might be subject to many changes, which are all included in the appended claims. Moreover, all the details may furthermore be replaced by other technically equivalent elements, and the materials may be different depending on the needs, without departing from the scope of protection of the invention defined by the appended claims.