ELECTRIC BICYCLE

Abstract

An electric bicycle is described with a propulsion unit comprising two pedals, an electric motor to assist pedaling, a first driving toothed wheel connected by a free-wheel to the pedals, and a second driving toothed wheel which is coaxial with the first toothed wheel and connected to the motor to receive rotary torque therefrom, Two chains transfer driving torque from the first and second toothed wheel to two gears of a wheel of the bicycle.

An electronic circuit controls electrical power generated by the electric motor, and preferably stores it into the battery.

Claims

1. Electric bicycle comprising: a propulsion unit comprising two pedals an electric motor to assist pedaling, a first driving toothed wheel connected by a free-wheel to the pedals, a second driving toothed wheel which is coaxial with the first toothed wheel and connected to the motor to receive rotary torque therefrom, a first chain for transferring driving torque from the first toothed wheel to a first pinion of a wheel of the bicycle, a second chain for connecting the second toothed wheel and a second pinion rotatably integral with the wheel, a battery to power the electric motor, an electronic circuit for controlling electrical power generated by the electric motor, and preferably storing it into the battery.

2. Electric bicycle as claimed in claim 1 or 11 or 12, wherein the first toothed wheel has a diameter different from that of the second toothed wheel.

3. Electric bicycle according to claim 1 or 11 or 12, wherein the second toothed wheel has a diameter smaller than that of the first toothed wheel.

4. Electric bicycle according to claim 1 or 11 or 12, wherein the second toothed wheel has a diameter smaller than that of the second gear.

5. Electric bicycle according to claim 4, wherein the transmission ratio between the second toothed wheel and the second gear is 3:1 to 6:1, e.g. 5:1.

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. (canceled)

11. Electric bicycle according to claim 1, wherein the first and second chains are arranged on the same side of the bicycle.

12. Electric bicycle according to claim 1, wherein the first and second chains are arranged on opposite sides of the bicycle.

13. Electric bicycle according to claim 1 or 11 or 12, comprising: a first speed sensor, a second sensor for detecting the state of downhill motion of the bicycle, and the electronic circuit is configured for detecting the state of downhill motion of the bicycle via the second sensor, detecting the speed of the bicycle via the first sensor, controlling the electric motor so that it behaves like an electric generator by converting mechanical energy received through the second chain.

14. Electric bicycle according to claim 1 or 11 or 12, wherein the second driving toothed wheel is selectively connectable to the first toothed wheel by means of a clutch or a joint.

15. Electric bicycle according to claim 1 or 11 or 12, wherein the electronic circuit is configured for detecting the state of prolonged stop of the bicycle by means of a sensor or a command from a user, and if there is a prolonged stop, controlling the electric motor so that it behaves like an electric generator to generate on the second chain a torque opposing to the motion of the bicycle.

16. Electric bicycle according to claim 13, wherein the second driving toothed wheel is selectively connectable to the first toothed wheel by means of a clutch or a joint.

17. Electric bicycle according to claim 13, wherein the electronic circuit is configured for detecting the state of prolonged stop of the bicycle by means of a sensor or a command from a user, and if there is a prolonged stop, controlling the electric motor so that it behaves like an electric generator to generate on the second chain a torque opposing to the motion of the bicycle.

18. Electric bicycle according to claim 14, comprising: a first speed sensor, a second sensor for detecting the state of downhill motion of the bicycle, and the electronic circuit is configured for detecting the state of downhill motion of the bicycle via the second sensor, detecting the speed of the bicycle via the first sensor, controlling the electric motor so that it behaves like an electric generator by converting mechanical energy received through the second chain.

19. Electric bicycle according to claim 14, wherein the electronic circuit is configured for detecting the state of prolonged stop of the bicycle by means of a sensor or a command from a user, and if there is a prolonged stop, controlling the electric motor so that it behaves like an electric generator to generate on the second chain a torque opposing to the motion of the bicycle.

20. Electric bicycle according to claim 15, comprising: a first speed sensor, a second sensor for detecting the state of downhill motion of the bicycle, and the electronic circuit is configured for detecting the state of downhill motion of the bicycle via the second sensor, detecting the speed of the bicycle via the first sensor, controlling the electric motor so that it behaves like an electric generator by converting mechanical energy received through the second chain.

21. Electric bicycle according to claim 15, wherein the second driving toothed wheel is selectively connectable to the first toothed wheel by means of a clutch or a joint.

Description

[0038] Further advantages will become clear from the following description, which refers to a preferred embodiment of a bicycle in which:

[0039] FIG. 1 shows a top view of components of an electric bicycle;

[0040] FIG. 2 shows a top view of components of a second electric bicycle.

[0041] Equal numbers in the figures indicate equal or substantially equal parts.

[0042] FIG. 1 shows a first variant of motorization for an electric bicycle (not shown).

[0043] The propulsion of the bicycle is ensured by a propulsion unit 10 from which two pedals 12 come out and which houses an electric motor to assist pedaling.

[0044] The pedals 12 and the electric motor have independent and coaxial shafts arranged along an axis. X1

[0045] The pedals 12 are connected to a toothed wheel 22 by means of a free-wheel, while the motor shaft is connected—or selectively connectable via a clutch or joint—to a second toothed wheel 24.

[0046] The toothed wheel 24 is engaged with a chain 30 to transfer or receive torque to/from a pinion 40 of a wheel 14 of the bicycle, rotatable about an axis X2 parallel to the axis X1. The pinion 40 is always rotationally integral with the wheel 14.

[0047] A second chain 32 connects the toothed wheel 22 to a pinion assembly 42 of the shift gearbox mounted on the opposite side of the wheel 14 with respect to the pinion 40. The chain 32 transfers muscle force from the pedals 12 to the group 42 and is movable on the pinion assembly 42 by a derailleur (not shown). Optionally the pinion assembly 42 may consist of a single pinion.

[0048] As can be seen from FIG. 1, the chains 30, 32 are placed on opposite sides with respect to an imaginary plane on which the wheel 14 lies (a plane P orthogonal to the axis X1 and X2). This allows the comfortable assembly of the pinion assembly 42, which can optionally be also consisting of a single pinion, or of one group provided with many pinions.

[0049] FIG. 2 shows a second motorization variant.

[0050] This time the chains 30, 32 are placed on the same side with respect to an imaginary plane on which the wheel 14 lies (a plane orthogonal to the axis X1 and X2). This allows to limit the overall bulk of the chains 30, 32, e.g. for the ankles of the rider.

[0051] For the two variants, there is also a battery (not shown) to supply the electric motor.

[0052] An electronic circuit (not shown) controls the operation of the motor both when it delivers power to assist pedaling, and when it is used as electric power generator while the bicycle runs downhill. The generated energy can be stored in whole or in part in the battery, according to the control of the electronic circuit on the energy flow delivered by the motor.

[0053] The electronic circuit is configured to regulate the energy recovery and/or to brake the bicycle running downhill, e.g. by dissipating the energy without sending it to the battery. All the operating combinations are possible.