WO2017060812A1

WO2017060812A1 - Device for pedal-assisted velocipede and wheel

Info

Publication number: WO2017060812A1
Application number: PCT/IB2016/055922
Authority: WO
Inventors: Samuela DE GIACOMI
Original assignee: Drake S.R.L.
Priority date: 2015-10-05
Filing date: 2016-10-04
Publication date: 2017-04-13
Also published as: EP3359442A1; ITUB20154183A1

Abstract

A device for pedal-assisted velocipede (1), associable to a wheel (2) of the velocipede (4), comprises an electrical energy storage unit (5) and an electric motor (7) wherein the stator (71) is associable to a frame portion (6) of the velocipede and the rotor (72) is associable to the wheel (2). The electric motor (7) has a maximum rated power (Pn), and is operable both as a motor to deliver mechanical power and as a dynamo for the storage of electrical energy in the storage unit. A limitation device limits the power deliverable by the motor to a limited power (L) less than the maximum rated power (Pn). When the electric motor is functioning in dynamo mode, it generates an electric power greater with respect to the value of the limited power (L) and less than or equal to the maximum rated power (Pn).

Description

DESCRIPTION

"DEVICE FOR PEDAL-ASSISTED VELOCIPEDE AND WHEEL"

[0001] This invention pertains, in general, to the sector of pedal-assisted velocipedes. In particular, the invention relates to a device for pedal-assisted velocipede and a wheel associated with that device.

[0002] As is known, pedal-assisted velocipedes are equipped with an electric motor that acts as an aid delivering mechanical power during pedalling.

[0003] In conventional pedal-assisted velocipedes, such as bicycles, the electric motor is housed in correspondence of the hub of the wheel and the electric power supply for such a motor is provided by a battery pack placed on the bicycle frame. In other words, therefore, the battery and the motor are connected in a separate manner respectively to the frame and the wheel. Since the battery pack is generally bulky and heavy, it is necessary to place this battery pack either on the oblique tube, vertical tube or rear rack, compromising the aesthetics and weight of the bicycle.

[0004] In addition, it is possible to find installation kits on the market comprising motor and battery pack to install on conventional bicycles so as to perform a retrofit. However, these kits are complicated to install for an average user who does not always have the necessary technical skills for such an installation, which requires not only the installation of the wheel with the motor, but also the battery pack on the frame and an electronic controller on the handlebars.

[0005] Furthermore, the electric motor traditionally installed on pedal-assisted bicycles has a predefined maximum rated output (for example 250 watts according to current European directives and the traffic laws in Italy) , which must be cut-off when the vehicle reaches 25 km/h or the cyclist stops pedalling.

[0006] Some pedal-assisted systems allow energy recovery when the bicycle is going downhill. Energy is recovered thanks to the use of the electric motor in dynamo mode, which generates electricity to recharge the battery pack. However, the electricity produced is generally insufficient to provide an adequate and quick charging of the battery pack, which, in any case, requires a subsequent manual charge from a source of electricity.

[0007] The purpose of this invention is to overcome the above limitations of the known technique by means of improved charging and duration of the battery pack, while at the same time ensuring simple installation and easy use on conventional bicycles, without compromising the aesthetics of the bicycle.

[0008] According to the invention, this purpose is achieved by a device for pedal-assisted velocipede according to claim 1 and by a wheel for velocipedes according to claim 13.

[0009] Preferred embodiments of the invention are defined in the dependent claims.

[0010] The characteristics and advantages of the device for pedal-assisted velocipedes according to this invention will be apparent from the following description, given by way of non-limiting example, in accordance with the accompanying figures, in which:

[0011] - Figure 1 shows a device for pedal-assisted velocipedes according to an embodiment of this invention mounted on the front wheel of a bicycle;

[0012] - Figure 2 shows a device for pedal-assisted velocipedes according to an embodiment of the invention;

[0013] - Figure 3 shows an exploded view of the device for pedal-assisted velocipedes according to a further embodiment of the invention;

[0014] - Figure 4 is an exploded view of the battery pack according to an embodiment of the invention;

[0015] - Figure 5 is a perspective view of the intermediate holder element and the batteries in position of pre- insertion in seats formed on the intermediate holder element, according to an embodiment of the invention;

[0016] - Figure 6 shows a functional block diagram of the device for pedal-assisted velocipedes according to an embodiment of the invention.

[0017] In accordance with the accompanying figures, reference number 1 indicates, in its entirety, a device for pedal-assisted velocipede 1, for example for a bicycle or rickshaw, or for a four-wheel bicycle (used especially in sea-side resorts), or for a scooter, or a light three-wheeled wagon and similar. This device 1 is suitable to be associated with a wheel 2 of the velocipede 4 and comprises an electric energy storage unit 5 and an electric motor 7, having a maximum rated power Pn. This rated power Pn is preferably less than 5 kW and even more preferably is equal to 1000W or 1500W.

[0018] Preferably, the term associated means that the device is operatively connected to the wheel so as to transfer mechanical power to the wheel and, even more preferably, it means that the device is incorporated in the wheel.

[0019] The electric motor, preferably a brushless electric motor, comprises a stator 71 associable to a frame portion 6 of the velocipede 4 and a rotor 72 is associable to the wheel 2 of the velocipede.

[0020] Preferably, the rotor 72 is mechanically associated to the wheel 2 by means of spokes that connect the rim of the wheel 2 to the rotor 72 itself. [0021] Preferably, the device 1 is associated to the front wheel of the velocipede. In this way, installation operations on any conventional bicycle are far easier, since the driver does not have to work on the bicycle chain. However, in an optional embodiment, the device is also associable to the rear wheel and, in this case, the propulsion pedals assembly 8 of the velocipede is associated to the rotor by means of motion transmission means 10, such as a chain pinion system, preferably also provided with a free wheel system.

[0022] The electric motor 7 is operable in two modes: as a motor to deliver mechanical power, Pm, to the wheel and/or as a dynamo for the accumulation of electrical energy Pe in the storage unit 5.

[0023] The device for velocipede 1 also comprises a device for limiting the power deliverable by the electric motor 7, suitable to limit the power supplied by the motor to a limited power L, when used as a motor. This limited power L is less than the maximum rated power Pn of the electric motor, and preferably is equal to the maximum power allowed by law for this type of velocipede, for example 250W in Italy. In other words, the limited power L is none other than the maximum mechanical power deliverable by the motor (Max(Pm)) once the limitation device is enabled. The limitation device of the deliverable mechanical power comprises for example a limitation control of the deliverable power from a drive unit 150 connected upstream of the electric motor, or an activatable/deactivatable physical device that limits the power delivered by the electric motor, for example a specific PWM (Pulse Width Modulation) control for a brushless electric motor or a dedicated electronic circuit .

[0024] It is clear that, only where required by national regulations governing the sector, preferentially the limitation device of the deliverable mechanical power can be always enabled during the mechanical power dispensing phase, in order to ensure that the maximum mechanical power deliverable by the motor is not exceeded.

[0025] During at least one phase of running of velocipede, the electric motor 7, when functioning as a dynamo, generates an electric power, Pe, greater than the value of the limited power L and less than or equal to the maximum rated power Pn.

[0026] In other words, during a phase of running in which for example the vehicle is going downhill, the electric motor is not limited to regenerating at most an electric power Pe equal to the maximum mechanical power generatable by the motor (as occurs in the prior art devices, in which, for example, max(Pe) = max(Pm) = Pn = 250W) . In fact, given that the deliverable mechanical power is limited (limited power L) to a value less than the maximum rated power Pn, when the electric motor is used as a dynamo, it is also able to generate an electric power Pe greater than the maximum generatable mechanical power Pm, but less than or equal to the maximum rated power Pn of the motor. This is equivalent to saying that the electric motor can generate an electric power Pe for charging the battery comprised between the value of a limited maximum mechanical power deliverable by the motor (the limited power L) and its maximum rated power Pn (L=max (Pm) <=Pe<=Pn, for example

250W=L=max (Pm) <=Pe<=Pn=1500W) .

[0027] In an advantageous embodiment of the device, for example shown in Figure 2, the device includes an outer casing suitable to be integral to the rim of the wheel 2 and the rotor 72 of the electric motor 7. For example, the outer casing is constituted by a plurality of parts joined together by suitable fastening means and encloses the electrical energy storage unit 5, the electric motor 7, the limitation device, and a device to manage the storage of electrical energy in the storage unit.

[0028] Preferably, the outer casing is constituted by two closure elements 11a and lib, for example in the form of a disc convex towards the outside, and by the rotor 72 itself. The two closure elements 11a, lib and the rotor 72 are joined together for example by means of suitable fixing screws 12 and, once joined like a "sandwich", also serve as protection against the weather or dirt, preventing their entry inside the region where the stator 71 is housed.

[0029] Preferably, between each of the two closure elements 11a, lib and the rotor 72 are interposed spacer rings 110,111,112. These spacer rings allow varying the space enclosed in the casing, thus allowing obtaining more or less space depending on the size of the energy storage unit to be housed. In the embodiment shown in Figure 2, there are two spacers 110,111 on one of the two sides of the rotor 72 and a spacer ring 112 on the other side of the rotor 72 in the axial rotation direction X.

[0030] Preferably, the device for pedal-assisted velocipedes 1 is installed at the centre of the wheel 2 of the velocipede in such a way that the outer casing of the device is constrained to the rim 2a of the wheel 2 and that the stator 5 of the electric motor 7 is connected to the frame portion 6 of the velocipede by means of the hub axle 9, integral with the stator 5. For example, the outer casing is constrained to the rim 2a by suitable spokes that radiate from the rim and engage perimeter holes 115 of the outer casing, arranged radially and circumferentially spaced in proximity of the outer edge 116 of the closure elements 11a, lib.

[0031] The outer casing is rotatable around the stator and is swivellingly coupled with the hub axle 9 by means of bearings housed in suitable bearing seats 91,92.

[0032] Preferably, the electric motor 7 is a brushless electric motor, for example a rotary motor wherein the rotor 72 is provided with permanent magnets and the stator 71 comprises a plurality of windings arranged along a ring, circumferentially spaced and activatable in such a way as to allow the rotation of the rotor around the stator.

[0033] Preferably, the electrical energy storage unit 5 is for example arranged internally to the stator in the radial direction that goes from the rotor 72 towards the hub axis 9 and comprises batteries 50 arranged around the rotation axis X of the electric motor 7. Each battery is arranged so as to have its main extension axis S arranged substantially parallel to the rotation axis X of the electric motor. In the case of cylindrical batteries, the main extension axis coincides with the axis of the cylinder .

[0034] In an embodiment, for example shown in Figure 4, the storage unit 5 is a disc-shaped battery pack with a hole in the middle 51 for the free passage of the hub axis 9. The battery pack is an assembly consisting of two closure discs 52, 53 each having battery seats 530 made on the inner face 52a, 53a of each of the two discs 52, 53 and suitable to house one of the two terminal portions 50a, 50b of the batteries 50.

[0035] Preferably, the batteries 50 are arranged so as to form subgroups 50', 50'', spaced circumferentially from each other. For example each subgroup includes 8 batteries and is spaced at least 1 cm from the other subgroup. The space 55 present between the subgroups 50', 50'' allows the passage of support arms that connect the stator 71 to the hub axis 9.

[0036] Furthermore, this space 55 helps air circulation and heat dissipation, for example during charging.

[0037] To each subgroup 50', 50'' is then associated a battery seat 530 on each inner face 52a, 53a of the two closure discs 52,53.

[0038] The electrical contacts between the individual batteries and/or between groups of batteries are provided by contact plates 56,56', suitably shaped to connect congruent poles of each battery and preferably arranged between the terminal portions of the batteries and the bottom 530' of the battery seats 530.

[0039] Preferably, to facilitate the operations of arranging the batteries during the assembly of the battery pack, the battery pack comprises an intermediate holder element 500 interposed between the two closure discs 52,53 and of similar shape to those discs, but preferably of thickness smaller than or equal to the discs 52,53. On the intermediate holder element 500, similarly to the closure discs 52,53 through seats 501 are formed from side to side of the intermediate holder element 500, suitable to hold in position and support the intermediate region 50c of each battery.

[0040] Preferably, moreover, a plurality of spacer elements 58a, 58b in the form of internally threaded cylinders are arranged between the two closure discs to serve as supporting pillars of the discs and are fixed to these discs by means of fastening screws 580.

[0041] As shown in Figure 2 and in Figure 3, the storage unit 5 is preferably positioned at the centre of the device 1 in the axial direction X.

[0042] Preferably, the total thickness of the device for velocipedes 1 according to this invention, measured along the axial direction is comprised between 70 mm and 100 mm, preferably between 80 mm and 90 mm, even more preferably about 86 mm.

[0043] In addition, preferably, the maximum diameter D of the outer casing of the device 1 is comprised between 200 mm and 400 mm, preferably between 250 and 350 mm, still more preferably about 320 mm.

[0044] The device for velocipede 1, further comprises a processing and control unit 13, operatively connected to the electric motor 7 and adapted to control its activation.

[0045] Preferably, the processing and control unit 13 is contained within the outer casing and is for example housed in a housing 13' formed on the storage unit. As is evident in the embodiment of Figure 3, the battery pack does not have the shape of an entire disc with hole in the centre, but has a wedge-shaped interruption (i.e., a housing 13' ) in the circular crown, inside which is housed the processing and control unit.

[0046] Preferably, together with the processing and control unit, the device for velocipede 1 also comprises a detection device of the inclination the velocipede 132, operatively connected to the processing unit and control unit and suitable to detect the inclination of the velocipede in motion with respect to a given reference inclination.

[0047] Furthermore, the device for velocipede 1 is also provided with a torque detection device suitable to detect the torque of the electric motor 7.

[0048] Preferably, this device is configured to detect the torque of the motor by measuring the current absorbed by the windings included in the motor, compared to the applied voltage and considering the typical torque curve of the motor in use.

[0049] Preferably, the processing and control unit 13 is configured in such a way as to control the power delivery of the electric motor as a function of the torque detected by the torque detection device and/or as a function of the inclination detected by the inclination detection device.

[0050] For example, the power delivery of the electric motor is regulated so as to maintain substantially constant the power that is requested by the rider of the velocipede, irrespective of the type of path he is confronting, for example a certain specific effort power W pre-set by the rider. In other words, the mechanical power generated by the electric motor will be regulated according to the inclination of the path: when going uphill, the electric motor delivers a higher mechanical power with respect to a delivery power for a level path so as to maintain constant the pedalling effort of the rider. Furthermore, in a similar but opposite manner, in case of going downhill, the motor functions as a dynamo with a braking action such as to maintain constant the pedalling effort of the rider and simultaneously generate an electrical power suitable to charge the electrical energy storage unit.

[0051] Preferably, the processing and control unit 13 comprises storage means configured to store a predetermined assistance percentage and/or a predetermined energy recovery percentage. The specific effort power W is preferably a function of the stored predetermined assistance percentage. Similarly, the amount of electrical energy stored in the storage unit 5 is preferably a function of the predetermined energy recovery percentage. In this way, it is possible to set both the amount of effort and the amount of energy recovery (and thus downhill braking) .

[0052] In an embodiment, the device for velocipede 1, further comprises a braking detection device 140, suitable to detect an index signal of the amount of braking set by the rider. Such a braking detection device is preferably a special linear pressure sensor suitable for measuring the force applied by the hand to the brake lever .

[0053] In other embodiments, this braking detection device is for example a distance sensor, suitable to measure the distance of the brake brushes with respect to the wheel rim, or is a linear sensor suitable for measuring a relative distance between the brake shoes.

[0054] The braking intensity thus acts in a proportional way on the energy recovery by the electric motor.

[0055] The braking detection device is operatively connected with the processing and control unit 13, for example by wireless communication means (preferably using the ANT+ communication protocol) and when an index signal of a braking amount set by the rider is detected, the processing and control unit 13 activates the electric motor 7 to operate in dynamo mode so as to exert a braking action on the wheel as a function of the index signal of the braking amount. In other words, the electric motor is used as a regenerative brake. This advantageously allows recovering energy that would otherwise be dissipated as heat and saving wear on the brake brushes.

[0056] Always for the purpose of maximising energy recovery, the device for a velocipede 1 further comprises a step-up converter (DC/DC) , suitable to raise the voltage generated by the electric motor at a low number of revolutions up to a predetermined charging voltage level, suitable to charge the storage unit. For example, in the case of using 36-volt batteries, it will be necessary to raise the voltage to this value, even for a low number of revolutions of the electric motor.

[0057] Preferably, the batteries used are batteries with a nominal voltage of 3.6V connected in series to achieve a rated voltage of 36 volts.

[0058] A block diagram that shows the operative connection between the main components of the device for velocipedes, according to an embodiment of the invention, is shown in Figure 6. The processing and control unit 13 includes a processor 130, preferably 32-bit, a processor for wireless communication 131, suitable to manage communication via Bluetooth, ANT+ and/or Wi-Fi protocols with other remote devices, a MEMS gyroscope 132 suitable to provide information about the inclination of the velocipede on at least three axes, a stabilised power management module 133, a module 134 for managing the charging/discharging of the batteries 50 (battery management system, BMS) and a module for identifying the state of motion/rest 135 of the velocipede.

[0059] The processing and control unit 13 also comprises wireless communication means 136, for example a Bluetooth module, or a Wi-Fi module and respective communication antennas, suitable to communicate remotely with a portable device 137, for example a smartphone, tablet or smartwatch .

[0060] Preferably, the wireless communication means 136, are configured to also communicate remotely with the braking detection devices 140 and with a device for detecting the rotation speed of the wheel and/or of the electric motor and the pedalling cadence 141, to example an optical or magnetic encoder.

[0061] For the activation of the electric motor, the processing and control unit is preferably connected with a motor driver unit 150, suitable to convert the signals processed and coming from the processing and control unit 13 into electrical currents of value adequate to the operation of the electric motor. This motor driver unit can also be integrated on the same electronic card as the processing and control unit. The signals coming from the processing and control unit are therefore interpretable by the motor driver unit 150, which sends the adequate electrical signals to the electric motor.

[0062] In an embodiment, the processing and control unit 13 is configured to receive a signal relating to the heart activity of the rider, for example by means of wireless communication with a heart rate monitor worn by the rider. In this case, the processing and control unit is configured to regulate the power delivery of the electric motor as a function of this signal relating to heart activity .

[0063] Preferably, the wireless communication protocol between the heart rate monitor and the processing and control unit is the ANT+ protocol.

[0064] By way of example, when the processing and control unit 13 receives a cardiac activity signal comprised in a predefined range of values, for example between 90 and 130 beats per minute, it generates a signal suitable to adjust the motor power delivery so as to provide pedalling assistance as a function of the number of beats. Preferably, once a certain minimum or maximum number of heartbeats is reached, assistance by the electric motor is disabled. For example, below 90 beats per minute or above 130 beats per minute, the power delivered by the electric motor is interrupted, while for intermediate values, the power delivery is a function of cardiac activity, for example proportional to the number of beats.

[0065] In a preferred embodiment of the invention, when the velocipede is stopped for a given time interval, the processing and control unit 13 is activated in "sleep mode" mode for an indefinite time interval, in order to minimise consumption of battery charge. In other words, the device according to this invention is substantially turned off. When the operator starts pedalling, after a certain number of pedal revolutions detected by the rotation sensors of the motor (for example the device for detecting the rotation of the wheel speed and/or of the electric motor and the pedalling cadence 141), the device is automatically turned on. It is turned on by the processing and control unit 13, which, as soon as it detects a certain number of pedal revolutions and/or a certain number of revolutions of the wheel (for example 2-3 pedal rotations), exits from "sleep mode" and enters active mode for the adequate functioning of the device and all related functionalities.

[0066] Preferably, the processor 130 is configured to manage the aforementioned phases of automatic turning on and off of the device 1 or an automatic turning-on device is specially configured to automatically turn on and enter the "sleep mode" of the pedal-assisted device for 1.

[0067] According to an aspect of this invention, the device for velocipedes 1 described above is suitable to be mounted on a conventional bicycle wheel in order to then be easily installed on a standard bicycle frame.

[0068] Innovatively, the device for pedal-assisted velocipede according to this invention ensures a faster and more efficient charging of the electrical energy storage device, thanks to the motor's ability to generate much more electrical power during charging with respect to the prior art devices.

[0069] It is clear that the generation of an electric power Pe greater than the maximum deliverable mechanical power (limited) L can also occur for only short stretches during running, depending on the battery charge conditions, or depending on the road or the current power delivered by the cyclist while pedalling. It should be noted that the possibility of generating electric power Pe greater than the maximum mechanical power, not only continuously but also from time to time (for short stretches) ensures, in any case, a more efficient and effective charging of the electrical energy storage unit with respect to prior art devices (which provide for only a recharge with a theoretical maximum power equal to the deliverable mechanical power, i.e., for example 250W in Italy) .

[0070] In addition, the management of the automatic charging of the storage unit as a function of the inclination of the bicycle (for example when going downhill) or as a function of a power surplus during pedalling by the rider, further allows increasing the effectiveness and rapidity of charging.

[0071] Even more advantageously, since the battery pack is enclosed inside the device positioned at the centre of the wheel and given the particular arrangement of the batteries with their axis parallel to the rotation axis of the wheel, the duration of the batteries is improved due to the ventilation generated by the rotary motion of the outer casing, which helps to dissipate the heat generated during recharging.

[0072] Also advantageously, the use of the electric motor as a regenerative brake when the rider executes a braking of moderate intensity allows recovering further energy and thus increasing the rapidity and amount of charge of the battery pack.

[0073] It is clear that one skilled in the art, in order to meet contingent needs, may make changes to the invention described above, all contained within the scope of protection defined by the following claims.

Claims

1. Device for pedal-assisted velocipede (1), for example for a pedal-assisted bicycle, suitable to be associated to a wheel (2) of the velocipede (4), comprising:

- an electrical energy storage unit (5) ;

- an electric motor (7), having a maximum rated power (Pn) , and comprising a stator (71) associable to a frame portion (6) of the velocipede and a rotor (72) associable to the wheel (2), wherein said electric motor (7) is operable as a motor to provide mechanical power and/or as a dynamo for the storage of electricity in said storage unit ( 5 ) ;

- a limitation device of the power output from the motor to a limited power (L) , said limited power (L) being less than the maximum rated power (Pn) ;

wherein said electric motor (7), when functioning as a dynamo, at least in a moving phase of the velocipede, generates an electric power greater than said limited power (L) value and less than or equal to the maximum rated power (Pn) .

2. Device for velocipede (1), according to claim 1, having an outer casing suitable to be integral with the wheel rim (2a) and with the rotor (72) of the electric motor (7), wherein said outer casing contains the electrical energy storage unit (5), the electric motor (7), the limitation device, a control device of electrical energy storage (50) in the storage unit (5) .

3. Device for velocipede (1) according to claim 2, further comprising:

- a processing and control unit (13), contained in the outer casing and operatively connected to the electric motor (7) to drive the actuation of said electric motor (7) ;

- a detection device of the inclination the velocipede (132), operatively connected to the processing and control unit (13) and suitable to detect the inclination of the velocipede in motion with respect to a given reference inclination;

a torque detection device, suitable to detect the torque transmitted to the wheel (2) by the electric motor

(7) .

4. Device for velocipede (1) according to claim 3, wherein the processing and control unit (13) is configured to regulate the power output of the electric motor depending on the inclination of the velocipede in motion, so as to maintain substantially constant the power required by the rider of the velocipede, for example a specific effort power (W) , pre-set by the rider .

5. Device for velocipede (1) according to claim 4, wherein the processing and control unit (13) comprises storage means configured to store a predetermined percentage of assistance and/or a predetermined percentage of energy recovery and wherein the specific effort power (W) is a function of said predetermined percentage of assistance or wherein the amount of electrical energy stored in the accumulator is a function of said predetermined percentage of energy recovery.

6. Device for velocipede (1) according to any of the claims from 3 to 5, wherein the processing and control unit (13) is configured to receive a signal relative to the rider's cardiac activity and to adjust the power output of the electric motor depending on said signal relative to cardiac activity.

7. Device for a velocipede (1) according to any of the previous claims, further comprising a braking detection device (140), suitable to detect a signal index of the amount of braking imposed by the rider, wherein the electric motor (7) is operated in dynamo mode in order to operate a braking action on the wheel as a function of the signal index of the amount of braking.

8. Device for a velocipede (1), according to claim 7, wherein the braking detection device (140) comprises wireless communication means with the processing and control unit (13), for example configured for communication via the ANT + Protocol.

9. Device for a velocipede (1) according to any of the previous claims, further comprising a step-up converter, suitable to raise the voltage generated by the electric motor at low number of revolutions up to a predetermined charging voltage level.

10. Device for a velocipede (1) according to any of the previous claims, wherein the electric energy storage unit comprises a plurality of batteries (50) arranged around the axis of rotation (X) of the electric motor (7), each of said plurality of batteries (50) having the main extension axis (S) substantially parallel to the axis of rotation of the electric motor (X) .

11. Device for a velocipede (1), according to claim 10, wherein the electric energy storage unit (5) is a disc^¬ shaped battery pack with a hole in the middle (51), wherein said battery pack is an assembly consisting of two closure discs (52, 53) each having battery seats (530) made on the inner face (52a, 53a) of each of the two discs (52, 53) and suitable to house one of the two terminal portions (50a, 50b) of the batteries (50) .

12. Device for a velocipede (1) according to any of the claims from 3 to 11, wherein the processing and control unit (13) is configured to automatically activate the device for a velocipede 1, when a certain number of revolutions of the wheel or a specific number of pedal strokes is detected.

13. Wheel (1) for velocipede comprising a device (1) according to any of the previous claims suitable to be mounted on a standard frame of a bicycle.