ADJUSTABLE FRICTION RING TRANSMISSION FOR A VEHICLE OPERABLE USING MOTOR POWER AND/OR PEDAL POWER

Abstract

A friction ring transmission for a vehicle operable using motor power and/or pedal power, including a crankshaft for pedal cranks, in particular, for an electric bicycle, the friction ring transmission including an inner friction ring and an outer friction ring, and at least one rotatable double tapered roller situated on a roller carrier, which frictionally engages with the inner friction wheel and the outer friction ring, in each case with a contact force, when a torque is transmitted via the friction ring transmission, a force return device for transmitting a contact force from one friction ring to the other friction ring being situated in a power flow path from the inner friction ring to the outer friction ring, one of the friction rings being rotatably fixedly situated in relation to the force return device and the other friction ring being rotatably situated in relation to the force return device.

Claims

1-17. (canceled)

18. A friction ring transmission for a vehicle operable using motor power and/or pedal power, the vehicle including a crankshaft for pedal cranks, the friction ring transmission comprising: an inner friction ring and an outer friction ring; at least one rotatable double tapered roller situated on a roller carrier, which frictionally engages with the inner friction ring and the outer friction ring, in each case with a contact force, when a torque is transmitted via the friction ring transmission; a force return device for transmitting a contact force from one of the inner and outer friction rings to the other of the inner and outer friction rings, the force return device situated in a power flow path from the inner friction ring to the outer friction ring, one of the inner and outer friction rings being rotatably fixedly situated in relation to the force return device and the other of the inner and outer friction rings being rotatably situated in relation to the force return device; and an adjusting device to adjust a gear ratio, the adjusting device being movable along an adjustment path which extends in the direction of a center axis of the inner and outer friction rings, the adjusting device extending less than 360 degrees around a center axis of the roller carrier.

19. The friction ring transmission as recited in claim 18, wherein the vehicle is an electric bicycle.

20. The friction ring transmission as recited in claim 18, wherein the force return device extends inside the inner and outer friction rings.

21. The friction ring transmission as recited in claim 18, wherein the adjusting device extends through a section of a housing of the friction ring transmission and is rotatably fixedly connected to the roller carrier.

22. The friction ring transmission as recited in claim 21, wherein the roller carrier, the adjusting device, and at least one section of the housing of the friction ring transmission, are non-rotatingly situated and the adjusting device, which is fitted as an arm originating from the roller carrier and movable along the adjustment path, extends through the section of the housing.

23. The friction ring transmission as recited in claim 21, further comprising: a servomotor for adjusting the adjusting device.

24. The friction ring transmission as recited in claim 18, further comprising: two annular expanding clutches through which the force return device extends, at least one of the expanding clutches being situated between the force return device and one of the inner and outer friction rings.

25. The friction ring transmission as recited in claim 18, wherein the force return device is situated around the crankshaft and is an integral sleeve.

26. The friction ring transmission as recited in claim 18, wherein the force return device includes a section extending radially away from the crankshaft wherein the section is for connecting to one of the friction rings or the section is integrally designed with one of the inner and outer friction rings.

27. The friction ring transmission as recited in claim 18, wherein a pilot transmission, which increases a speed of the friction wheel transmission relative to the drive speed of the pilot transmission, is connected in front of the friction ring transmission, the pilot transmission being a planetary gear.

28. The friction ring transmission as recited in claim 18, wherein the force return device is rotatably fixedly connected to a drive element of the friction ring transmission.

29. The friction ring transmission as recited in claim 28, wherein the drive element is a shaft or a gear wheel.

30. The friction ring transmission as recited in claim 28, wherein the drive element is an output sun wheel of a planetary gear.

31. The friction ring transmission as recited in claim 18, wherein a smaller one of the inner and outer friction rings is rotatably situated relative to the force return device.

32. The friction ring transmission as recited in claim 27, further comprising: a summation gear wheel for summing torques of the crankshaft and an electric motor, on a drive of the pilot transmission or of the friction ring transmission.

33. The friction ring transmission as recited in claim 18, wherein the inner friction ring and the outer friction ring are situated circumferentially around the crankshaft.

34. The friction ring transmission as recited in claim 18, wherein a roller bearing is situated between the force return device and one of the inner and outer friction rings, in which a pressure line to raceways between contact points of a roller body is at an acute angle to the center axis of the roller carrier, the roller bearing being as an angular ball bearing or a tapered roller bearing.

35. The friction ring transmission as recited in claim 34, wherein the force return device is radially surrounded by the roller bearing, the inner raceway of the roller bearing being situated on an outer surface of the force return device and is axially supported on the outer surface.

36. A vehicle operable using motor power and/or pedal power, the vehicle having a friction ring transmission including: an inner friction ring and an outer friction ring; at least one rotatable double tapered roller situated on a roller carrier, which frictionally engages with the inner friction ring and the outer friction ring, in each case with a contact force, when a torque is transmitted via the friction ring transmission; a force return device for transmitting a contact force from one of the inner and outer friction rings to the other of the inner and outer friction rings, the force return device situated in a power flow path from the inner friction ring to the outer friction ring, one of the inner and outer friction rings being rotatably fixedly situated in relation to the force return device and the other of the inner and outer friction rings being rotatably situated in relation to the force return device; and an adjusting device to adjust a gear ratio, the adjusting device being movable along an adjustment path which extends in the direction of a center axis of the inner and outer friction rings, the adjusting device extending less than 360 degrees around a center axis of the roller carrier.

37. The vehicle as recited in claim 36, further comprising: a servomotor for adjusting the adjusting device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Exemplary embodiments of the present invention are described in detail below with reference to the figures.

[0025] FIG. 1 schematically shows a representation of an electric bicycle, which includes a specific embodiment of the friction ring transmission according to the present invention.

[0026] FIG. 2 shows a perspective view of an integrated drive unit including a friction ring transmission according to the present invention.

[0027] FIG. 3 shows a perspective view of the integrated drive unit in the specific embodiment shown in FIG. 2 without a housing surrounding the friction ring transmission.

[0028] FIG. 4 shows a cross section extending through a center axis of the roller carrier through the drive unit shown in FIG. 3 including the summation gear wheel, pilot transmission, friction ring transmission and rear transmission.

[0029] FIG. 5 shows an enlarged detail with a double tapered roller from the cross section shown in FIG. 4.

[0030] FIG. 6 shows a second specific embodiment of the drive unit, including a second specific embodiment of the friction ring transmission including a force return device designed as a sleeve and an angular ball bearing.

[0031] FIG. 7 shows a third specific embodiment of the drive unit, including a third specific embodiment of the friction ring transmission including a different force return device designed as a sleeve.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0032] FIG. 1 schematically shows an electric bicycle 100, in which a drive unit 1 is situated centrally on the frame. Seat tube 105, down tube 106 and chain stay 107, in particular, converge at or near drive unit 1. The mounting of the crankshaft for pedal arms 102 and 103 is integrated into drive unit 1. The drive unit includes a chain ring 8, which constitutes the output of drive unit 1. Chain ring 8 transmits a torque from drive unit 1 via a chain 108 and a sprocket 109 to a rear wheel 110. Drive unit 1 includes an electric motor not explicitly shown. The electric motor may be supplied with power from a battery 104.

[0033] FIG. 2 shows a perspective view of an integrated drive unit 1, which includes a friction ring transmission 2, a pilot transmission 3, a rear transmission 4, a summation gear wheel 5, an electric motor 6, an intermediate transmission 7, an output 8 and a crankshaft 9. Crankshaft 9 is depicted without its cranks, each of which may be attached to a toothed connection at the end of crankshaft 9, other types of connections also being conceivable. Friction ring transmission 2 includes a housing 10, which at least radially surrounds friction ring transmission 2 except for an opening 11. An adjusting lever 12 as part of the friction ring transmission protrudes through opening 11 out of the interior of the housing. This adjusting lever is displaceable in the longitudinal direction of the crankshaft 9, as a result of which the gear ratio of friction ring transmission 2 is adjustable. The adjustment path of the adjusting device designed with adjusting lever 12 therefore extends in the inside of opening 11 and in the longitudinal direction of crankshaft 9 in relation to adjusting lever 12. The adjustment path is at least approximately linear.

[0034] Intermediate transmission 7 includes an intermediate shaft 13, at one end of which a sprocket 14 is situated, which meshes with summation gear wheel 5. The mounting of intermediate shaft 13 is not depicted. Sprocket 14 has a significantly smaller diameter than summation gear wheel 5. An intermediate gear wheel 15, which has a significantly larger diameter than sprocket 14, is situated at the other end of intermediate shaft 13. Intermediate gear wheel 15 meshes with an output gear wheel 16 of an electric motor 6, which is part of drive unit 1. This effectuates a significant reduction of the rotational speed of electric motor 6 relative to the rotational speed of summation gear wheel 5 via intermediate transmission 7. A mechanical connection between electric motor 6 and housing 10 of friction ring transmission 2 is not depicted.

[0035] Rear transmission 4 is designed as a planetary gear, the output of which is planet carrier 17. Planet carrier 17 is rotatably fixedly connected to output sprocket 8 of the integrated transmission unit. The planetary gear is driven by sun wheel 35, whereas annulus gear 36 is rotatably fixedly connected to housing 10. An outer cover of rear transmission 4 is not depicted, which may be designed to be fully covered.

[0036] FIG. 3 shows a perspective view of the same integrated drive unit 1 as in FIG. 2, but with the difference that housing 10 of friction ring transmission 2 is omitted, so that its details are visible. A part of the annulus gear of pilot transmission 3 designed as a planetary gear is also omitted so that its planet wheels 18 and its planet carrier 19 are visible. Features and elements described in FIG. 1 are provided with the same reference numerals and are not separately described again. Reference is made to FIG. 1.

[0037] Friction ring transmission 2 includes an outer friction ring 20, which frictionally engages with multiple double cones 23. Double cones 23 are situated on a roller carrier 22 and revolve on axles 25 fastened thereto. Roller carrier 22 has a non-visible part located further inside of friction ring transmission 2. Outer friction ring 20 is connected to an expanding clutch 21 which, in turn, is supported via an axial bearing 24 on a housing part not depicted. Expanding clutch 21 expands in an axial direction of crankshaft 9 when a drive torque from summation gear wheel 5 acts on friction ring transmission 2. This increases the contact force between outer friction ring 20 and double tapered rollers 23. Adjusting lever 12 is connected to roller carrier 25, which is designed for displaceable movement in the axial direction of crankshaft 9. Expanding clutch 21 may include springs or may be connected to springs, which create a pretensioning force between outer friction ring 20 and double tapered rollers 23.

[0038] FIG. 4 shows a perspective view of a cross section through integrated drive unit 1, which is depicted in FIG. 3. The cross section extends through center axis M of crankshaft 9 and adjusting lever 12. Features and elements previously described in FIGS. 2 and 3 are identified by the same reference numerals and are not separately described again. Reference is made to FIGS. 2 and 3.

[0039] The interior part of roller carrier 22 is depicted in FIG. 4. This part is connected via roller axles 25 to the outer part of roller carrier 22. Also depicted is inner friction ring 26, which frictionally engages double cones 23. Inner friction ring 26 is assigned an expanding clutch 27, which is supported against housing 10 via an axial bearing 28. Expanding clutch 28, like expanding clutch 21, is designed in such a way that it is expanded when a drive torque acts on summation gear wheel 5 in the longitudinal direction of crankshaft 9, thereby increasing the contact force between inner friction ring 26 and double tapered rollers 23. Expanding clutch 27 may include springs or may be connected to springs, which create a pretensioning force between inner friction ring 26 and double tapered rollers 23. The diameter of expanding clutch 21 is smaller than that of expanding clutch 27.

[0040] The power flow through the part of drive unit 1 depicted in FIG. 4 is described below. A torque may be introduced into crankshaft 9 via not depicted cranks by pedal power. The torque in crankshaft 9 is introduced via a freewheel 29 into summation gear wheel 5. Freewheel 29 ensures that a reverse pedaling is possible while the remainder of the depicted transmissions revolves in accordance with the rotations of its output 8. Summation gear wheel 5 is rotatably fixedly connected to annulus gear 30 of pilot transmission 3, so that both revolve together. Planet wheels 18 of pilot transmission 3 are mounted on planet shafts 31, which are fastened to housing 10. Thus, the position of planet wheels 18, except for their inherent rotation, is fixed. Sun wheel 32 of the pilot transmission is rotatably fixedly connected to a sleeve 33, which conducts the torque from sun wheel 32 to friction ring transmission 2. Because of the gear ratio of pilot transmission 3, the rotational speed of sleeve 33 is greater than the rotational speed of summation gear wheel 5. Sleeve 33 is rotatably attached to crankshaft 9. A drive disk 34, which further conducts the torque from sleeve 33 via expanding clutch 21 to outer friction ring 20, is pressed onto sleeve 33. The torque is then transmitted to double tapered rollers 23. Since roller carrier 22 is not rotatable, but only displaceably situated in the longitudinal direction of crankshaft 9, the torque is completely transferred from outer friction ring 20 into a rotation of double tapered rollers 23. These transmit the torque further to inner friction ring 26, with which they also frictionally engage. The torque is transmitted via expanding clutch 27 further to sun wheel 35 of rear transmission 4. Annulus gear 36 of rear transmission 4 is rotatably fixedly connected to housing 10. Thus, the torque is transmitted to planet carrier 17 of planet wheels 37 of rear transmission 4. As previously mentioned, planet carrier 17 of rear transmission 4 is rotatably fixedly connected to output 8 designed preferably as a sprocket, so that the torque may be removed from integrated transmission unit 1 at this output, for example, via a chain.

[0041] Outer friction ring 20 and inner friction ring 26 are, as previously mentioned, supported on housing 10 by assigned axial bearings 24 and 28. Thus, housing 10 in the specific embodiment of FIGS. 1 through 3 forms a force return device for the forces originating, in particular, from expanding clutches 21 and 27. These forces correspond to the forces pressing on double tapered rollers 23. Axial bearings 24 and 28 run respectively at the rotational speed of large friction ring 20 and at the rotational speed of small friction ring 26. Axial bearing 24 of the large friction ring, in particular, generates a relatively high frictional torque, because it exhibits a high rotational speed and also a large friction radius in many operating states.

[0042] Crankshaft 9 is situated concentrically to roller carrier 22, axial bearings 24 and 28, expanding clutches 21 and 27 as well as to small friction ring 26 and large friction ring 20. Pilot transmission 3 and rear transmission 4, both of which are designed as planetary gears, are also situated concentrically to crankshaft 9. The same also applies for summation gear wheel 5 and the sprocket of output 8.

[0043] FIG. 5 shows a detail of the cross section depicted in perspective view in FIG. 4, which includes friction ring transmission 2, in a view shown as a half section. Identical features and elements are identified by identical reference numerals and are not described separately again. Reference is made in this regard to FIG. 4. In FIG. 5, it is clearly apparent that drive disk 34 includes an edge 34a bent in the axial direction, via which torque is conducted from sleeve 33 to expanding clutch 21.

[0044] FIG. 6 shows a somewhat larger detail of the view shown in FIG. 5, but with the difference that FIG. 6 shows a second specific embodiment of drive unit 1 having a second specific embodiment of friction ring transmission 2. Identical features and elements are identified by the same reference numerals as in the previously described figures and are not described separately again.

[0045] Unlike the first specific embodiment shown in FIG. 5, the second specific embodiment in FIG. 6 shows no axial bearings 24 and 28, with which the friction ring transmission is supported on housing 10. Instead, sleeve 33, which is fitted in the second specific embodiment with an axial force absorption section 33a, serves as a force return device. The force exerted by inner friction ring 26 on double tapered rollers 23 is transmitted via expanding clutch 27 to an angular ball bearing 38. This angular ball bearing 38 is attached or pressed with its inner ring onto sleeve 33. One edge of an axial surface of the inner ring of angular ball bearing 38 is supported axially on axial force absorption section 33a of sleeve 33. The axial forces, which correspond to the contact forces on the double tapered rollers 23, are conducted by the sleeve further to pressure disk 34, which conducts them via its axial section 34a further to expanding clutch 21 and to outer friction ring 20. In this way, the power flow, with which double cone 23 is clamped, is closed off. Angular ball bearing 38 revolves at the differential speed of outer friction ring 20 and of inner friction ring 26. This rotational speed is lower in many operating states than the rotational speed of inner or outer friction rings 26, 21, compared to housing 10, which preserves the bearing.

[0046] FIG. 7 shows the same view of a cross section of friction ring transmission 2 in half-section as in FIG. 6, but with the difference that in FIG. 7, a third specific embodiment of friction ring transmission 2 is depicted. Identical features and elements are identified by identical reference numerals and are not described separately again. Reference is made to FIG. 5 and to the previously described figures.

[0047] Unlike the specific embodiment of FIG. 6, the force return device in the specific embodiment of FIG. 7 is implemented with an integrally designed sleeve 33, which includes a radially extending section 33b, which is part of the force return device. Drive disk 34 is therefore not loaded or barely loaded by the returning contact force of the friction rings and may transmit as its main load the torque from sun wheel 32 of the pilot transmission to large friction ring 20. A more reliable fail-safe operation results from the integral design of sleeve 33 with its radially projecting section 33b, because an alternative conceivable connection between drive disk 34 and sleeve 33 cannot fail due to its integral design.