Transmission for a Bicycle

Abstract

A transmission for a bicycle includes a transmission input shaft (1) which is rotationally fixable to a crankshaft (2) and also includes first, second and third planetary gear sets (PS1, PS2, PS3) which are operatively connected to one another. An element of the first planetary gear set (PS1) is rotationally fixed to the transmission input shaft (1). The first planetary gear set includes a planet gear encompassing a first planetary gear stage (3) and a second planetary gear stage (5). A first ring gear (6) is engaged with a gear teeth section of the first planetary gear stage (3) and is rotationally fixable to a transmission housing (4) with a first shift element (s1). A second ring gear (7) is engaged with a gear teeth section of the second planetary gear stage (5) and is rotationally fixable to the transmission housing (4) with a second shift element (S2).

Claims

1-15. (canceled)

16. A transmission for a bicycle, comprising: a transmission input shaft (1) rotationally fixable to a crankshaft (2); a first planetary gear set (PS1), a second planetary gear set (PS2), and a third planetary gear set (PS3), which are operatively connected to one another, wherein an element of the first planetary gear set (PS1) is rotationally fixed to the transmission input shaft (1), wherein the first planetary gear set includes a planet gear with a first planetary gear stage (3) and a second planetary gear stage (5), wherein a first ring gear (6), which is engaged with a gear teeth section of the first planetary gear stage (3), is rotationally fixable to a transmission housing (4) with a first shift element (S1), and wherein a second ring gear (7), which is engaged with a gear teeth section of the second planetary gear stage (5), is rotationally fixable to the transmission housing (4) with a second shift element (S2).

17. The transmission of claim 16, wherein: the planet gear of the first planetary gear set (PS1) has a third planetary gear stage (8); or the planet gear of the first planetary gear set (PS1) has a third planetary gear stage (8), and a third ring gear (9), which is engaged with a gear teeth section of the third planetary gear stage (8), is rotationally fixable to the transmission housing (4) with a third shift element (S3).

18. The transmission of claim 16, wherein the element of the first planetary gear set (PS1) is a carrier.

19. The transmission of claim 16, wherein: a sun gear of the first planetary gear set (PS1) is rotationally fixed to a carrier of the second planetary gear set (PS2); or a sun gear engaged with the first planetary gear stage (3) is rotationally fixed to the carrier of the second planetary gear set (PS2).

20. The transmission of claim 16, wherein a sun gear of the second planetary gear set (PS2) is rotationally fixable to the transmission housing (4) with a fourth shift element (S4).

21. The transmission of claim 16, wherein two elements of the second planetary gear set (PS2) are rotationally fixable to each other with a fifth shift element (S5).

22. The transmission of claim 16, wherein a ring gear of the second planetary gear set (PS2) is rotationally fixed to a sun gear of the third planetary gear set (PS3).

23. The transmission of claim 16, wherein a ring gear of the third planetary gear set (PS3) is rotationally fixable to the transmission housing (4) with a sixth shift element (S6).

24. The transmission of claim 16, wherein two elements of the third planetary gear set (PS3) are rotationally fixable to each other with a seventh shift element (S7).

25. The transmission of claim 16, wherein a carrier of the third planetary gear set (PS3) is rotationally fixed to a transmission output shaft (10).

26. The transmission of claim 25, further comprising an electric machine operatively connected or operatively connectable to the transmission output shaft (10).

27. The transmission of claim 26, wherein the electric machine is operatively connected or is operatively connectable with an eighth shift element to the transmission output shaft via one or more of a spur gear drive, a belt drive, and a differential drive.

28. The transmission of claim 16, wherein: a sun gear of the second planetary gear set (PS2) is rotationally fixable to the transmission housing (4) with a fourth shift element (S4); two elements of the second planetary gear set (PS2) are rotationally fixable to each other with a fifth shift element (S5); a ring gear of the second planetary gear set (PS2) is rotationally fixed to a sun gear of the third planetary gear set (PS3); a ring gear of the third planetary gear set (PS3) is rotationally fixable to the transmission housing (4) with a sixth shift element (S6); two elements of the third planetary gear set (PS3) are rotationally fixable to each other with a seventh shift element (S7); and a carrier of the third planetary gear set (PS3) is rotationally fixed to a transmission output shaft (10).

29. A bottom bracket, comprising the transmission of claim 16 and a crankshaft, wherein the transmission input shaft (1) is rotationally fixed to the crankshaft (2).

30. The bottom bracket of claim 29, further comprising a bottom bracket shell (11), wherein the transmission is arranged within a cavity of the bottom bracket shell (11).

31. A bicycle comprising the transmission of claim 16.

32. A bicycle, comprising the bottom bracket of claim 29.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The subject matter of examples aspects of the invention is schematically represented in the figures and is described in the following with reference to the figures, wherein identical or identically operating elements are mostly provided with the same reference characters. Wherein:

[0028] FIG. 1 shows a schematic of the transmission according to the invention, according to a first exemplary embodiment;

[0029] FIG. 2 shows a table of values for the stationary transmission ratio;

[0030] FIG. 3 shows a shift pattern for the transmission represented in FIG. 2; and

[0031] FIG. 4 shows a schematic of the transmission according to the invention, according to a second exemplary embodiment.

DETAILED DESCRIPTION

[0032] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0033] The transmission represented in FIG. 1 is designed to be rotationally symmetrical with respect to a central axis M of the transmission, whereby only the upper half of the transmission is represented. The transmission includes a transmission input shaft 1 which is rotationally fixed to a crankshaft 2. The crankshaft 2 includes a pedal at each of end of the crankshaft 2. In addition, the transmission includes a first planetary gear set PS1, a second planetary gear set PS2, and a third planetary gear set PS3, which are operatively connected to one another. A carrier of the first planetary gear set PS1 is rotationally fixed to the transmission input shaft. The first planetary gear set PS1 includes a planet gear having a first planetary gear stage 3 and a second planetary gear stage 5.

[0034] A first ring gear 6 is engaged with the first planetary gear stage 3 and is rotationally fixable to a transmission housing 4 with the aid of a first shift element S1. A second ring gear 7 is engaged with the second planetary gear stage 5 and is rotationally fixable to the transmission housing 4 with the aid of a second shift element S2.

[0035] A sun gear of the first planetary gear set PS1, which is engaged with the first planetary gear stage PS1, is rotationally fixed to a carrier of the second planetary gear set PS2. A sun gear of the second planetary gear set P2 is rotationally fixable to the transmission housing 4 with the aid of a fourth shift element S4. In addition, the sun gear of the second planetary gear set PS2 is rotationally fixable to a ring gear of the second planetary gear set PS2 with the aid of a fifth shift element S5. Moreover, the ring gear of the second planetary gear set PS2 is rotationally fixed to a sun gear of the third planetary gear set PS3.

[0036] A ring gear of the third planetary gear set PS3 is rotationally fixable to the transmission housing 4 with the aid of a sixth shift element S6. In addition, the ring gear of the third planetary gear set PS3 is rotationally fixable to the sun gear of the third planetary gear set PS3 with the aid of a seventh shift element S7. A carrier of the third planetary gear set PS3 is rotationally fixed to a transmission output shaft 10.

[0037] The planetary gear sets are arranged coaxially to the central axis M of the transmission and/or the crankshaft 2. In addition, the transmission output shaft 10 is arranged coaxially to the central axis M of the transmission and/or the crankshaft 2. The transmission is arranged in a cavity of a bottom bracket shell 11 of a bottom bracket of a bicycle (not represented).

[0038] The transmission output shaft 10 is rotationally fixed to a traction mechanism carrier which is not represented in the figures. The traction mechanism carrier may be, for example, a sprocket or a belt pulley and is utilized for transmitting the torque output by the transmission to a rear wheel (not represented).

[0039] FIG. 2 shows the values for the stationary transmission ratio. In this case, PS1a indicates the stationary transmission ratio for the first planetary gear set PS1 with respect to the first planetary gear stage 3 and PS1b indicates the stationary transmission ratio for the first planetary gear set PS1 with respect to the second planetary gear stage 5. As is apparent from the table, the second planetary gear set PS2 and the third planetary gear set PS3 have the same stationary transmission ratio.

[0040] FIG. 3 shows the shift pattern of the transmission represented in FIG. 1. In addition, the table shows the ratio i for the individual gears between the transmission input shaft 1 and the transmission output shaft 10. The ratio steps phi are also shown in the table. The letter x indicates that the particular shift elements are engaged. It is clear from FIG. 3 that the transmission has eight gears.

[0041] The transmission represented in FIG. 4 differs from the transmission represented in FIG. 1 in that the planet gear of the first planetary gear set PS1 encompasses a third planetary gear stage 8. A third ring gear 9 is engaged with the third planetary gear stage 8 and may be rotationally fixable to the transmission housing 4 with the aid of a third shift element S3. The diameter of the third planetary gear stage 8 is larger than the diameter of the first planetary gear stage 3 and is smaller than the diameter of the second planetary gear stage 5.

[0042] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims.

REFERENCE CHARACTERS

[0043] 1 transmission input shaft [0044] 2 crankshaft [0045] 3 first planetary gear stage [0046] 4 transmission housing [0047] 5 second planetary gear stage [0048] 6 first ring gear [0049] 7 second ring gear [0050] 8 third planetary gear stage [0051] 9 third ring gear [0052] 10 transmission output shaft [0053] 11 bottom bracket shell [0054] M central axis [0055] S1 first shift element [0056] S2 second shift element [0057] S3 third shift element [0058] S4 fourth shift element [0059] S5 fifth shift element [0060] S6 sixth shift element [0061] S7 seventh shift element [0062] PS1 first planetary gear set [0063] PS2 second planetary gear set [0064] PS3 third planetary gear set