Abstract
An electric drive for a bicycle is disclosed. The drive includes an electric motor including an drive shaft, a driven shaft connected in a rotationally fixed manner to a driving gear for coupling to a wheel drive, and a transmission structured and arranged to drivingly connect the drive shaft to the driven shaft. The transmission includes a driven wheel, which is connected in a rotationally fixed manner to the driven shaft in a rotational drive direction, and at least two output gears. The at least two output gears includes a first output gear and a second output gear that each engage with the driven gear offset to one another in a circumferential direction to drive the driven wheel.
Claims
1-24. (canceled)
25. An electric drive for a bicycle, comprising: an electric motor including an drive shaft; a driven shaft connected in a rotationally fixed manner to a driving gear for coupling to a wheel drive; a transmission, structured and arranged to drivingly connect the drive shaft to the driven shaft; wherein the transmission includes a driven wheel, which is connected in a rotationally fixed manner to the driven shaft in a rotational drive direction, and at least two output gears, the at least two output gears including a first output gear and a second output gear that each engage with the driven gear offset to one another in a circumferential direction to drive the driven wheel.
26. The drive according to claim 25, wherein a first axis of rotation, about which the first output gear rotates, and a second axis of rotation, about which the second output gear rotates, are arranged inside the transmission in a stationary manner.
27. The drive according to claim 25, wherein a first axis of rotation, about which the first output gear rotates, and a second axis of rotation, about which the second output gear rotates, are arranged geometrically between an output axis, about which the driven shaft rotates, and an input axis, about which the drive shaft rotates.
28. The drive according to claim 25, wherein: the first output gear is connected in a rotationally fixed manner to a first intermediate gear; the second output gear is connected in a rotationally fixed manner to a second intermediate gear; and the transmission has an input gear, structured and arranged to engage with the first intermediate gear and with the second intermediate gear.
29. The drive according to claim 28, wherein: the first intermediate gear has a larger number of teeth than the first output gear; and the second intermediate gear has a larger number of teeth than the second output gear.
30. The drive according to claim 29, wherein: the first intermediate gear radially engages over the driven gear on a first axial side; and the second intermediate gear radially engages over the driven gear on a second axial side.
31. The drive according to claim 30, wherein the input gear is axially divided into a first partial input gear that engages with the first intermediate gear on the first axial side of the driven gear, and a second partial input gear that engages with the second intermediate gear on the second axial side of the driven gear.
32. The drive according to claim 29, wherein the first intermediate gear and the second intermediate gear radially engage over the driven gear on the same axial side.
33. The drive according to claim 32, wherein: the first intermediate gear engages with a first axial section of the input gear, and the second intermediate gear engages with a second axial section of the input gear, wherein the second axial section is arranged on the input gear axially offset to the first axial section.
34. The drive according to claim 33, wherein: the first axial section of the input gear has a first axial end of the input gear and is axially spaced apart from a second axial end of the input gear; the second axial section of the input gear has the second axial end of the input gear and is axially spaced apart from the first axial end of the input gear; the first intermediate gear engages with the input gear axially spaced apart from the second axial end of the input gear; and the second intermediate gear engages with the input gear axially spaced apart from the first axial end of the input gear.
35. The drive according to claim 29, wherein the first intermediate gear and the second intermediate gear engage with the input gear axially offset to one another.
36. The drive according to claim 35, wherein the first intermediate gear and the second intermediate gear radially engage over one another.
37. The drive according to claim 28, wherein: a first transmission path leads from the input gear via the first intermediate gear and the first output gear to the driven gear; a second transmission path leads from the input gear via the second intermediate gear and the second output gear to the driven gear; and the first transmission path and the second transmission path define the same transmission ratio.
38. The drive according to claim 37, wherein: the first intermediate gear and the second intermediate gear have the same number of teeth; and the first output gear and the second output gear have the same number of teeth.
39. The drive according to claim 37, wherein: the first intermediate gear and the second intermediate gear have different numbers of teeth; and the first output gear and the second output gear have different numbers of teeth.
40. The drive according to claim 28, wherein the input gear is connected in a rotationally fixed manner to the drive shaft.
41. The drive according to claim 28, wherein the transmission has a planetary transmission drivingly arranged between the drive shaft and the input gear.
42. The drive according to claim 41, wherein the planetary transmission has a sun gear is drivingly coupled directly or indirectly to the drive shaft, a plurality of planet gears, a planet carrier, and a ring gear, wherein the planet carrier is connected in a rotationally fixed manner to the input gear.
43. The drive according to claim 25, wherein the driven shaft is provided by a pedal shaft.
44. The drive according to claim 25, wherein the driven shaft is a hollow shaft and is coaxially permeated by a pedal shaft, wherein the pedal shaft is connected in a rotationally fixed manner to the driven shaft in the rotational drive direction.
45. The drive according to claim 25, wherein at least one of the at least two output gears, the input gear, and the driven gear is composed of plastic.
46. A bicycle, comprising: a pedal shaft; a wheel drive for driving a driven wheel of the bicycle; an electric drive, the electric drive including: an electric motor including an drive shaft; a driven shaft connected in a rotationally fixed manner to a driving gear for coupling to a wheel drive; a transmission, structured and arranged to drivingly connect the drive shaft to the driven shaft; wherein the transmission includes a driven wheel connected in a rotationally fixed manner to the driven shaft in a rotational drive direction, and at least two output gears that respectively engage with the driven gear offset to one another in a circumferential direction to drive the driven wheel.
47. The bicycle according to claim 46, wherein the at least two output gears are arranged on a side of the driven shaft facing away from a ground surface when in operation.
48. The bicycle according to claim 22, wherein, apart from the driven wheel, the transmission is arranged above the driven shaft when operating on a surface.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] In each case schematically,
[0041] FIG. 1 shows a schematic diagram of an electric drive,
[0042] FIG. 2 shows a schematic diagram of the electric drive, but in the case of another embodiment,
[0043] FIG. 3 shows a schematic diagram of a part of the electric drive, but in the case of a further embodiment,
[0044] FIG. 4 shows an axial view onto a portion of the drive,
[0045] FIG. 5 shows a radial view of the drive from FIG. 4,
[0046] FIG. 6 shows a radial view of the drive, but in the case of another embodiment,
[0047] FIG. 7 shows an axial view of the drive from FIG. 6,
[0048] FIG. 8 shows a radial view of the drive, but in the case of another embodiment,
[0049] FIG. 9 shows an axial view of the drive, but in the case a yet again different embodiment.
DETAILED DESCRIPTION
[0050] According to FIGS. 1 and 2, a bicycle 1, which is illustrated only in the area of an electric drive 2 here, comprises a pedal shaft 3 as well as a wheel drive 4, which is preferably embodied as chain drive 4 or as belt drive 4. A universal drive 4 is generally also conceivable. The wheel drive 4 serves to drive a driven wheel, which is not shown here, of the bicycle 1, which is preferably a rear wheel of the bicycle 1. The bicycle 1 furthermore comprises the above-mentioned drive 2. In the completely mounted state of the bicycle 1, the pedal shaft 3, which is part of the structural volume of the drive 2 here, is in each case connected in a rotationally fixed manner to a pedal crank, which is not shown here, on its longitudinal ends, on which a pedal is in each case located, which is also not shown here.
[0051] According to FIGS. 1 to 9, the electric drive 2 comprises an electric motor 5, a driven shaft 6, and a transmission 7. The electric motor 5 has a drive shaft 8, which rotates about an input axis 9. The driven shaft 6 rotates about an output axis 10 and is connected in a rotationally fixed manner to a driving gear 11, which is preferably a gearwheel. Via the driving gear 11, the drive 2 is connected to the wheel drive 4, in particular to the chain drive 4 or to the belt drive 4, respectively, or to the universal drive 4, respectively.
[0052] The transmission 7 comprises a driven gear 12, preferably a gearwheel, which is connected in a rotationally fixed manner to the output shaft 6 in a rotational drive direction 13, which is suggested in FIGS. 4, 7, and 9 by means of an arrow. The transmission 7 further has at least two output gears, preferably a gearwheel each, namely a first output gear 14 and a second output gear 15. In the case of other examples, more than two output gears 14, 15 can also be present. In the schematic diagrams of FIGS. 1 and 2, only one of the output gears 14, 15 can in each case be seen. The respective output gear 14, 15 serves to drive the driven gear 12 and engages with the driven gear 12 for this purpose. The two output gears 14, 15 are thereby arranged offset to one another on the driven gear 12 in the circumferential direction 16 of the driven gear 12 as suggested by a double arrow in FIGS. 4, 7, and 9. To transfer the drive power of the electric motor 5 to the driven gear 12 via the two output gears 14, 15, a power distribution is realized in the transmission 7.
[0053] This power distribution can generally distribute the drive power to the at least two output gears 14, 15 in an arbitrary, suitable ratio. An even or symmetrical power distribution, respectively, to the output gears 14, 15 is preferred here. In the case of exactly two output gears 14, 15, a power distribution in the ratio of 1:1 is thus preferred.
[0054] The first output gear 14 thereby rotates about a first axis of rotation 40, while the second output gear 15 rotates about a second axis of rotation 41. These axes of rotation 40, 41 are stationary, i.e., the two axes of rotation 40, 41 are arranged in a stationary manner inside the transmission 7. In other words, the two axes of rotation 40, 41 do not change their spatial position inside the transmission 7 during operation of the drive 2.
[0055] It can be gathered from FIGS. 4 to 9, how the two output gears 14, 15 in each case individually engage with the driven gear 12, spaced apart from one another in the circumferential direction 16. The load of the respective engagement point is thereby significantly reduced. A first engagement point between the first output gear 14 and the driven gear 12 is thereby identified with 17, while a second engagement point between the second output gear 15 and the driven gear 12 is identified with 18.
[0056] According to FIGS. 4 to 9, the first output gear 14 is connected in a rotationally fixed manner to a first intermediate gear 19, while the second output gear 15 is connected in a rotationally fixed manner to a second intermediate gear 20. In the simplified illustrations of FIGS. 1 and 2, only one of the intermediate gears 19, 20 can be seen in each case. The transmission 7 is furthermore equipped with an input gear 21, which in each case engages with the first intermediate gear 19 and with the second intermediate gear 20. In the examples of FIGS. 1, 2, and 4 to 9, this engagement gear 21 is connected in a rotationally fixed manner to the drive shaft 8. In contrast, FIG. 3 shows another embodiment merely in an exemplary manner, in the case of which the input gear 21 is connected to the drive shaft 8 via further transmission sections. In the example of FIG. 3, the transmission 7 comprises a planetary transmission 22, via which the input gear 21 is connected to the drive shaft 8. In the usual way, the planetary transmission 22 thereby has a ring gear 23, planet gears 24, which engage with the ring gear 22, a planet gear carrier 25, on which the planet gears 24 are rotatably supported, and a sun gear 26, which engages with the planet gears 24. In the example of FIG. 3, the sun gear 26 is connected to the drive shaft 8 via a further transmission stage, which is formed by two gearwheels 27 and 28. The input gear 21 is connected in a rotationally fixed manner to the planet gear carrier 25 here.
[0057] In the case of the embodiments shown in FIGS. 4 to 9, the first intermediate gear 19 has a larger number of teeth than the first output gear 14. The second intermediate gear 20 likewise has a larger number of teeth than the second output gear 15. In the case of the embodiment shown in FIGS. 4 and 5, the first intermediate gear 19 and the second intermediate gear 20 are arranged on the same axial side of the driven gear 12 and radially engage over the driven gear 12 there. A radial overlap of the two intermediate gears 19, 20 by the driven gear 12 thus results in the axial view shown in FIG. 4.
[0058] In FIGS. 6 and 7, in contrast, it is provided that the first intermediate gear 19 radially engages over the driven gear 12 on a first axial side 29, while the second intermediate gear 20 radially engages over the driven gear 12 on a second axial side 30. In the case of an arrangement of the intermediate gears 19, 20, of the driven gear 12, and of the input gear 21 relative to one another, as in FIG. 4, an axially undivided, continuous input gear 21 can be used for driving the two intermediate gears 19, 20. In contrast, in the case of the relative arrangement of the intermediate gears 19, 20, of the driven gear 12, and of the input gear 21 relative to one another, as shown in FIG. 7, the divided embodiment of the input gear 21 as shown in FIG. 6 is preferred. According to FIG. 6, the input gear 21 is axially divided, so that it has a first partial input gear 21a and a second partial input gear 21b, which are axially spaced apart from one another and which are each independently connected in a rotationally fixed manner to the drive shaft 8. The first partial input gear 21a engages with the first intermediate gear 19 on the first axial side 29 of the driven gear 12. The second partial input gear 21b engages with the second intermediate gear 20 on the second axial side 30 of the driven gear 12. In the case of the arrangement shown in FIG. 7, a radial overlap results between the partial input gears 21a, 21b and the driven gear 12 in the axial viewing direction. The drive shaft 8 can thus be positionally radially close to the circumference of the driven gear 12.
[0059] In the example of FIG. 5, the two intermediate gears 19, 20 engage with the input ear 21 in the same axial section. The input gear 21 can thus be dimensioned approximately equally large as the two intermediate gears 19, 20. The intermediate gears 19, 20 and the input gear 21 can thus in particular be arranged in the same axial plane.
[0060] In contrast, FIG. 8 shows an embodiment, in the case of which the first intermediate gear 19 engages with a first axial section 31 of the input gear 21, while the second intermediate gear 20 engages with a second axial section 32 of the input gear 21. The second axial section 32 is thereby arranged on the input gear 21 axially offset to the first axial section 31. It can in particular be provided that the first axial section 31 of the input gear 21 has a first axial end 33 of the input gear 21 and is axially spaced apart from a second axial end 34 of the input gear 21. The second axial section 32 of the input gear 21, in contrast, can have the second axial end 34 of the input gear 21 and can be axially spaced apart from the first axial end 33 of the input gear 21. The first intermediate gear 19 engages with the input gear 21 axially spaced apart from the second axial end 34 of the input gear 21. The second intermediate gear 20 engages with the input gear 21 axially spaced apart from the first axial end 33 of the input gear 21. The first intermediate gear 19 and the second intermediate gear 20 thus engage with the input gear 21 axially offset to one another. A configuration according to FIG. 9 can thereby generally also be realized, in the case of which the first intermediate gear 19 and the second intermediate gear 20 engage over one another, viewed in the axial direction.
[0061] In the case of all of the embodiments shown here, a first transmission path and a second transmission path are embodied inside the transmission 7, which are in each case suggested by means of an arrow in FIG. 9 and which are identified with 35 for the first transmission path and with 36 for the second transmission path. The first transmission path 35 leads from the input gear 21 via the first intermediate gear 19 and via the first output gear 14 to the driven gear 12. The second transmission path 36 leads from the input gear 21 via the second intermediate gear 20 and via the second output gear 15 to the driven gear 12. Both transmission paths 35, 36 define the same transmission ratio. In the case of the embodiments of FIGS. 4 to 8, the first intermediate gear 19 has the same number of teeth as the second intermediate gear 20. The first output gear 14 likewise has the same number of teeth as the second output gear 15. The intermediate gears 19, 20 and the output gears 14, 15 can thus be realized as identical parts, which are interchangeable. In the example of FIG. 9, in contrast, it is provided that the two intermediate gears 19, 20 have different numbers of teeth. The two output gears 14, 15 simultaneously also have different numbers of teeth. In the example of FIG. 9, the first intermediate gear 19 has a larger number of teeth than the second intermediate gear 20. Proportionally thereto, the first output gear 14 then has a smaller number of teeth than the second output gear 15. The coordination of the number of teeth then takes place in such a way that the two transmission paths 35, 36 ultimately realize the same transmission ratio again.
[0062] In the preferred embodiments, the driven gear 12 is connected to the driven shaft 6 via a freewheel assembly 37 according to FIGS. 1 and 2. This freewheel assembly 37 transmits a torque from the driven gear 12 to the driven shaft 6 in the rotational drive direction 13. In a counter-rotational direction 38, which is suggested by means of an arrow in FIG. 4, which is oriented opposite to the rotational drive direction 13, the freewheel assembly 37, in contrast, allows for relative rotations between driven gear 12 and driven shaft 6. The driven shaft 6, for example, can thereby rotate in the rotational drive direction 13, while the driven gear 12 stands still or rotates with a lower speed than the driven shaft 6 in the rotational drive direction 13.
[0063] According to FIG. 2, the driven shaft 6 is advantageously embodied as hollow shaft and is coaxially permeated by the pedal shaft 3. The pedal shaft 3 is connected in a rotationally fixed manner to the driven shaft 6 in the rotational drive direction 13. The pedal shaft 3 is advantageously connected to the driven shaft 6 via a further freewheel assembly 39. This further freewheel assembly 39 operates between driven gear 12 and driven shaft 6 in the same way as the above-described freewheel assembly 37. The further freewheel assembly 39 accordingly transmits a torque from the pedal shaft 3 to the driven shaft 6 in the rotational drive direction 13, while it allows for a relative rotation between pedal shaft 3 and driven shaft 6 in the counter-rotational direction 38. The driven shaft 6 can thereby rotate in the rotational drive direction 13, while the pedal shaft 3 stands still or rotates in the counter-rotational direction 38 or rotates with a lower speed than the driven shaft 6 in the rotational drive direction 13.
[0064] Advantageously, the input axis 9 and the output axis 10 run parallel to one another, but radially spaced apart from one another. Axes of rotation 40, 41 of the first output gear 14 or of the first intermediate gear 19, respectively, and of the second output gear 15 or of the second intermediate gear 20, respectively, advantageously also extend parallel to the input axis 9 and parallel to the output axis 10.
[0065] Advantageously, the output gears 14, 15, the input gear 21, the intermediate gears 19, 20, and the driven gear 12 are made of plastic. In contrast, the pedal shaft 3 and/or the driven shaft 6, the drive shaft 8, and the driving hear 11 are advantageously made of metal.
[0066] As can in particular be gathered from FIGS. 4 to 7 and 9, the output gears 14, 15 are arranged geometrically between the drive shaft 8 and the driven shaft 6 in the case of the embodiments shown here. In the installed state of the drive 2, the drive shaft 8 is located on a side of the driven shaft 6 facing away from a surface not shown here, when the bicycle 1, which is equipped with the drive 2, stands or moves on this surface. Apart from the driven gear 12, the entire remaining transmission 7 is consequently located essentially above the driven shaft 6.
