ELECTRICALLY MOTORIZED WHEEL, PARTICULARLY FOR BICYCLES, WITH INCORPORATED MECHANICAL GEAR CHANGE

Abstract: An electrically motorized wheel, particularly for bicycles, comprising a hub (1) inside which an electrical motor (4) is housed in a fixed way with respect to the axis X of the wheel, its driving shaft being at right angles to the said axis X and having two sections (7, 8), projecting in diametrically opposite positions with respect to the motor casing (4), each of the said sections (7, 8) being connected mechanically, with its own gear ratio, to a crown wheel (15, 16), integral with an inner wall of the hub (1), by means of a respective pinion (13, 14) and a corresponding freewheel mechanism (9, 10), which allows transmission of the movement of each section (7, 8) only in a determined direction of rotation of the driving shaft, always obtaining the rotation of the hub in the same direction.

Description: "ELECTRICALLY MOTORIZED WHEEL, PARTICULARLY FOR BICYCLES, WITH INCORPORATED MECHANICAL GEAR CHANGE" The present invention refers to a motorized wheel for light vehicles in general, and particularly for bicycles, which is provided with an electric motor and a mechanical two-ratio gear change, which are housed in the hub of the said wheel. 5. Motorized wheel for bicycles are already known, and the electric motor housed in their hub is fed by a rechargeable battery, fixed to the bicycle frame, which allows a certain degree of autonomy and which can be connected or disconnected by the user by manoeuvering a special control. 10. There is also a publication (DE-A-27 02 541) relating to a motorized wheel, in particular for a child's bicycle, which incorporates a gear change, comprising wheelworks and levers which can be moved by means of a wire, for transmitting the rotary movement of the driving shaft pinion to one of two crown gears of different diameters made in the 15. wheel hub. Such a system is far too complicated and expensive, and it is easily subject to breaking, because of the continual engaging and disengaging of the different gears during gear changing. One aim of the present invention is to provide a motorized wheel of 20. the above mentioned type, provided with a gear change, which will be simple and economical to produce, and will eliminate or at least greatly reduce risks of the motorized device breaking or not working, by maintaining the various gears in mesh. Another aim of the invention is to provide a motorized wheel of the above type in which the gear shifting can take place automatically. Yet another aim of the invention is to provide a motorized wheel of 5. such type, which will allow the vehicle to be used with electric traction only or with muscular traction only, or with a combination of electric and muscular traction. The motorized wheel according to the invention is substantially characterized in that the shaft of the electric motor has two ends 10. which are opposed which respect to the axis of the wheel hub, each one being provided with a respective pinion in constant mesh with one or more concentric crown wheels foreseen on the wheel hub, and with different reduction ratios. The movement is transmitted to the two pinions by means of respective 15. free wheels, in such a way that each pinion is set in rotation only when the driving shaft rotates in the correct direction, while the other remains free. Since the two pinions work with different reduction ratios, passing from one ratio to the other takes place simply by reversing the 20. rotation of the driving shaft, which takes place immediately by inverting the feed polarity of the motor, by means of a commutator in the case of direct current, or by means of a motor inverter in the case of alternating current. Such inversion can be made automatic by means of an electronic circuit 25. on the basis of the current absorbed by the motor. When such current goes over a predetermined threshold it automatically reverses the rotation, connecting the higher reduction ratio and viceversa. In a first embodiment of the invention, the different reduction ratios are obtained by using bevel pinions with different diameters, which 5. engage with different concentric crown wheels at the same time. In a second embodiment of the invention, at least one of the two pinions is connected to the driving shaft by means of an epicycloidal reduction gear, with the two pinions engaging preferably with the same crown wheel, in this case. 10. According to another embodiment of the invention, at least one of the two bevel pinions engages with a corresponding bevel gear, which in turn operates a crown gear mounted outside a freewheel and engages with the inner profile of the crown wheel. Further characteristics of the invention will be explained more 15. clearly in the detailed description which follows, referring to unrestrictive exemplary embodiments thereof, illustrated in the appended drawings, in which: Figure 1 is a diagrammatic side view of a wheel for a bicycle with a motorized hub, according to the invention; 20. Figure 2 is a median section of the hub with incorporated electric motor and change-speed gear, according to a first embodiment; Figure 3 is a view similar to the one in figure 2 of a second embodiment of the change—speed gear, with one of the two pinions connected to the driving shaft by means of 25. epicycloidal gears; Figure 4 is a plan view illustrating only the epicycloidal gears; - A - Figure 5 is a view similar to the one in figure 2, illustrating a third embodiment of the change-speed gear, with both the pinions connected to the driving shaft by means of epicycloidal gears; 5. Figure 6 is a view similar to the one in figure 2, illustrating a fourth embodiment of the change-speed gear according to the invention, using a bevel gear pair; Figure 7 is a view similar to the one in figure 2, illustrating a fifth embodiment of the change-speed gear according to the invention, using a bevel gear pair. In figure 1 a motorized wheel according to the invention is shown in diagrammatic form, comprising a central hub 1, connected to a rim 2 by means of spokes 3. In some applications, the rim can be made on the outside of the hub 15. itself, thus eliminating the use of spokes. The wheel illustrated in figure 1 is in particular a metallic bicycle wheel, but it is obvious that it can be made from other materials, for example plastics and that it can be used for other light transport vehicles. 20. With reference now to figure 2, it will be noted that an electric motor 4 is located inside the casing of the hub 1, mounted in a fixed position with respect to the axis X of the wheel, locked to the bicycle fork by means of terminal pins 5. The hub 1 is freely rotatable around the axis X, or around the pins 5, thanks to 25. interposed bearings 6. Of course, in the case of a bicycle wheel, if it is mounted behind, a freewheel (not shown) will also be mounted on the hub 1, in order to allow traction by means of a chain also, in an already known manner. According to the invention, the driving shaft, whose axis is shown with Y and is at right angles to the axis X of the wheel, has two 5. diametrically opposed sections 7, 8, projecting from the casing of the motor 4. By means of a respective freewheel mechanism 9, 10, and related bearings 11, 12, a corresponding pinion 13, 14 in constant mesh with a respective crown wheel 15, 16, is connected to each of these sections 10. 7, 8 of the driving shaft. The two crown wheels 15, 16 are preferably applied to the same side of the casing of the hub 1 and have different diameters, and their axes coinciding with the axis X of the wheel. The two freewheels 9, 10 allow the transmission of the rotary movement of the driving shaft to the respective pinions 13, 14, only when the 15. motor rotates in the correct direction; for example, when the rotation of the driving shaft is right-hand, the pinion 13 transmits the movement and the pinion 14 is free, while when the rotation of the driving shaft is left-hand, the pinion 13 is free once more and the pinion 14 transmits the movement. Whichever pinion transmits the 20. movement, the wheel always turns in the same direction, making the vehicle move forward. A determined speed reduction ratio, therefore, corresponds to each direction of rotation of the driving shaft. The different speed ratios are, in this case, determined by the different diameters of the 25. pinions 13, 14 and of the corresponding crown wheels 15, 16. The passing from one ratio to the other obviously takes place by reversing the rotation of the driving shaft, which is brought about immediately just by inverting the feed polarity of the motor, in the case of direct current feed, or by means of an inverter in the case of alternating current feed. 5. The reversing of roτation can be effected by means of a special control, located for example on the handlebar of the bicycle with which the connection and disconnection of the motor may also possibly be controlled. In figure 2, reference number 17 indicates the feed wires of the 10. electric motor 4, coming from a battery, which is not shown, fixed at a convenient point on the bicycle frame. The reversing of the rotation of the motor, and hence the change of the speed ratio, can be made automatic by means of an electronic circuit, on the basis of the current absorbed, by fixing a determined 15. threshold S. In the starting phase of the vehicle the maximum reduction (pinion 13) is connected, the speed is minimum and there is maximum torque, and therefore current absorption is over the threshold S. As the vehicle gradually takes us speed, the absorbed current decreases, and at the moment when it falls below S, reversing of the 20. rotation of the motor takes place, which causes the pinion 13 to be free, and the larger diameter pinion 14 will transmit the movement, thus reducing the reduction ratio and allowing the vehicle to gain higher speed. When the current absorbed by the motor increases again, for example when going uphill, when the threshold S is crossed, the 25. rotation of the motor is reversed once more, causing the movement to be transmitted again by means of the pinion 13 with maximum reduction. The value of the threshold S of the current which produces the reversal of the rotation of the driving shaft will be selected on the basis of the different applications of the motorized wheel according to the invention. If the feed to the motor 4 is disconnected, for example if it is 5. desired to move the vehicle forward with muscular traction alone, both the pinions 13, 14 become free, thus preventing the motor motoring over. Obviously the motorized wheel according to the invention allows the vehicle to be used with muscular traction only, with electric traction 10. only or with a combination of muscular and electric traction. In the case of a bicycle, the motorized wheel will preferably be the one at the front, but the motorization may also be applied to the back wheel or even to both the wheels. From what has been stated above, the advantages of the solution 15. proposed by the invention are easy to see. It will be noted particularly that the two pinions 13, 14 are always in contact with the respective crown wheels 15, 16, thus eliminating all the drawbacks connected with engaging and disengaging, which are to be found with the already known solution previously described. 20. A brief description will now be given of the other embodiments of the invention, similar in concept to the, one in figure 2, and differing from the latter only in some structural parts. In the illustration of such embodiments the reference numbers used in figure 2 will be used to designate the same or similar parts. The embodiment according to figures 3 and 4 differs from the one in figure 2 only in that one of the two pinions, precisely the lower one 14 with reference to the figure, receives its movement from the driving shaft by means of epicycloidal gears 18, which engage with a 5. crown wheel 19 splined onto the corresponding section 8 of the driving shaft, and housed in a cylindrical box 20 integral with the casing of the motor 4. The shafts 21 however of the epicycloidal gears 18 are made integral with a cylindrical casing 22, containing the free wheel mechanism 12 and the bearings 11, for the transmission of the rotary 10. movement to the pinion 14, which in this case has the same diameter as the pinion 13, in such a way that both pinions 13, 14 can engage at the same time with the same crown wheel 15. In this embodiment, the maximum reduction ratio is found in correspondence with the epicycloidal unit. 15. According to the embodiment illustrated in figure 5, both pinions 13, 14 are connected to the respective sections 7, 8 of the driving shaft by means of epicycloidal units with different reduction ratios. In such figure the same reference numbers have been used for the two epicycloidal groups as those used in figures 3 and 4. 20. According to the embodiment in figure 6, the pinion 14 is a bevel pinion splined directly onto the section 8 of the driving shaft and engages with a corresponding bevel gear 23, whose shaft 24, which is at right angles to the axis Y of the driving shaft and parallel to the axis X of the wheel, operates, by means of the freewheel mechanism 10, 25. a pinion outside the same freewheel, which engages with the crown wheel 15, which has an inner toothing 15' as well as a lateral toothing. In this case, the higher reduction ratio is found in correspondence with the bevel gear pair. Finally, according to the embodiment in figure 7, the bevel gear pairs are foreseen, with different ratios, in correspondence with both 5. sections 7, 8 of the driving shaft, for transmitting movement to the crown wheel 15, by means of the freewheel mechanism 9, 10, with pinions outside the same freewheels. In such figure, the bevel gear which engages with the bevel pinion 13 is shown with 25, and its shaft, which is parallel to the shaft 24 of the bevel gear 23, is 10. shown with 26.

Claims: C L A I M S 1. A motorized wheel for vehicles, in particular bicycles, comprising a central hub (1) rotatably mounted on an axis X of the wheel, inside which an electric motor (4) is mounted, in such a way as to be fixed with respect to the axis X, and a mechanical change-speed 5. gear which allows the rotation of the motor (4) to be transmitted to the hub (1) with two different ratios, characterized in that the shaft of the motor ( Δ ) whose axis Y is at right angles to the axis X of the wheel, has two sections (7, 8) which project in diametrically opposed positions with respect to the casing of the motor (4) , the said 10. sections (7, 8) transmitting the rotation of the driving shaft to at least one crown wheel (15, 16), being integral with the casing of the hub (1) by means of a respective freewheel mechanism (9, 10), each coming into operation through a determined direction of rotation of the driving shaft. 15. 2. A motorized wheel according to claim 1, characterized in that a respective pinion (13, 1 ) is connected to each of the said sections (7, 8) through a respective freewheel mechanism (9, 10), each of said pinions engaging with a respective crown wheel (15, 16). 3. A motorized wheel according to claim 2, characterized in that 20. the said pinions (13, 14) have different diameters and engage v/ith different crown wheels (15, 16), which are concentric and have different diameters. 4. A motorized wheel according to claim 2, characterized in that the said pinions (13, 14) have the same diameter and engage with one 25. and the same crown wheel (15); epicycloidal reduction gears (18) being interposed between at least one of the said gears (13, 14) and the corresponding section (7, 8) of the driving shaft. 5. A motorized wheel according to claim 4, in which the said epicycloidal gears (18) mesh with a crown wheel (19) splined onto the 5. section (7) and/or (8) of the driving shaft and are housed in a cylindrical box (20) integral with the casing of the motor (4) , the shafts (21) of the epicycloidal gears (18) being made integral with a casing (22) housing the said freewheel mechanism (9, 10). 6. A motorized wheel according to claim 1 or 2, characterized in 10. that in correspondence v/ith at least one of the sections (7, 8) of the driving shaft a bevel gear pair (13, 25; 14, 23) is provided, which transmits the movement to an inner toothing (15') of the said crown wheel (15), by means of a countershaft (26, 24). 7. A motorized wheel according to claim 6, characterized in that 15. the said freewheel (9, 10) is interposed between the said countershaft (26, 24) and the said crown wheel (15) by means of pinions outside the freewheel. 8. A motorized wheel according to any one of the previous claims, characterized in that respective bearings (11, 12) are associated with 20. each freewheel (9, 10). 9. A motorized wheel according to any one of the previous claims, characterized in that it has a manual electric control for reversing the direction of the rotation of the shaft of the motor (4) and therefore the speed ratio. 25. 10. A motorized wheel according to any one of the previous claims, characterized in that a manual control is foreseen, with a potentiometer connected to an electronic circuit which controls the motor for a progressive variation of speed, with the possibility of cutting out or connecting the electric motor (4) , in such a way as to 5. allow the means on which the wheel is mounted to be operated with muscular traction, with electric traction or with a combination of muscular and electric traction. 11. A motorized wheel according to any one of the claims from 1 to 9, characterized in that it foresees an electronic circuit v/hich 10. automatically controls the reversing of the direction of rotation of the driving shaft, and therefore changes the reduction ratio obtaining different torques, for example on the basis of the current absorbed by the motor (4) . 12. A light vehicle, in particular a bicycle, provided with at 15. least one motorized wheel according to any one of the claims from 1 to 11.

Inventors: CANDERLE GIAMPIETRO, CANDERLE, GIAMPIETRO
Applicants: CANDERLE GIAMPIETRO, CANDERLE, GIAMPIETRO
Application year: 1992
Main classification: B60K7
IPC codes: B60K7, B60K17, B62M7, B62M23, F16H3