Bottom bracket transmission with a planetary design for a bicycle or pedelec

Abstract

The invention relates to a bottom bracket transmission with a planetary design for a bicycle or a pedelec (1) comprising a pedal crankshaft (Wan) as a drive and a transmission output shaft (Wab) as an output, as well as at least four further shafts (W1, W2, W3, W4), at least three planetary gear sets (RS1, RS2, RS3) arranged coaxially relative to the pedal crankshaft (Wan), and at least five shift elements (B1, B2, B3, F1, F2, F2', F2") for implementing at least six gears (V1, V2, V3, V4, V5, V6), wherein the pedal crankshaft (Wan) is connected to a second element of the second planetary gear set (RS2), wherein the pedal crankshaft (Wan) can be connected to a first element of the first planetary gear set (RS1) via a fourth shift element (F1) and a first shaft (W1), wherein the transmission output shaft (Wab) is connected to a first element of the second planetary gear set (RS2) and to a first element of the third planetary gear set (RS3), wherein a second element of the first planetary gear set (RS1) is connected to a third element of the second planetary gear set (RS2) via a second shaft (W2), wherein a third element of the first planetary gear set (RS1) is connected to a second element of the third planetary gear set (RS3) via a third shaft (W3), and wherein two elements of the third planetary gear set (RS3) can be connected to one another via a fifth shift element (F2, F2', F2") in order to block the third planetary gear set (RS3).

Description

[0001] Planetary bottom bracket gear for a bicycle or pedelec

[0002] The present invention relates to a planetary bottom bracket gear for a bicycle or pedelec, comprising a pedal crankshaft as the input and a transmission output shaft as the output, as well as at least four additional shafts, at least three planetary gear sets arranged coaxially with the pedal crankshaft, and at least five shifting elements for implementing at least six gears. Furthermore, the invention relates to a bicycle or pedelec with the bottom bracket gear.

[0003] For example, from the publication DE 10 2016 225 169 A1, a planetary gear transmission for a bicycle or pedelec is known. To achieve only four gears, the transmission comprises at least two planetary gear sets, of which at least one planetary gear set is necessarily designed as a space-consuming plus planetary gear set. Furthermore, at least four shifting elements are required. In another embodiment of the transmission, four additional gears are achieved by adding two additional shifting elements and another planetary gear set. Due to the intended interconnection or connection of the various planetary gear sets, the known transmission results in a space-consuming design.

[0004] Accordingly, the object of the present invention is to realize a bottom bracket gear of the type described at the beginning with the least possible construction effort and with the fewest possible components.

[0005] This object is achieved according to the invention by the features of patent claims 1 and 15, respectively. Advantageous and claimed developments emerge from the subclaims and the description as well as the drawings.

[0006] Thus, a bottom bracket gear with a planetary design for a bicycle or pedelec is proposed. The bottom bracket gear has a pedal crankshaft as the input and a transmission output shaft as the output, as well as at least four further shafts, wherein the output is preferably via a chain wheel, a belt wheel, or the like. Furthermore, the bottom bracket gear comprises three planetary gear sets, which are arranged coaxially to the pedal crankshaft, and five shifting elements for implementing at least six gears in the proposed bottom bracket gear. In order to provide a particularly effective and space-saving design for the bottom bracket gear, the pedal crankshaft Wan is connected to a second element of the second planetary gear set. Furthermore, the pedal crankshaft Wan can be connected to a first element of the first planetary gear set via a fourth shifting element and a first shaft.The transmission output shaft is connected to a first element of the second planetary gear set and to a first element of the third planetary gear set. A second element of the first planetary gear set is connected to a third element of the second planetary gear set via a second shaft. A third element of the first planetary gear set is connected to a second element of the third planetary gear set via a third shaft. To lock the third planetary gear set, two elements of the third planetary gear set can be connected to one another via a fifth shift element.

[0007] In this way, with the above-described connection of only three planetary gear sets and only five shifting elements, a particularly simple and compact design is achieved for the proposed bottom bracket gear. In addition, the geometric gear ratios of the bottom bracket gear ensure particularly low component loads and advantageously high gear efficiency.

[0008] For the mechanical connection of elements of the planetary gear sets, preferably only four additional shafts or shaft-like elements are used in addition to the input and output, whereby the term shaft does not exclusively refer to a cylindrical, rotatably mounted machine element for transmitting torque, but rather also to general connecting elements that connect the individual gear set elements to one another for torque transmission.

[0009] In order to achieve the space-saving arrangement in the proposed bottom bracket gear, it is provided that when the first shifting element is closed, the first shaft connected to the first element of the first planetary gear set is firmly connected to a housing; that when the second shifting element is closed, the third shaft connected to the third element of the first planetary gear set and to the second element of the third planetary gear set is firmly connected to the housing; and that when the third shifting element is closed, a fourth shaft connected to the third element of the third planetary gear set is firmly connected to the housing. Due to the above-described connection of the elements on the housing side by the provided shifting elements as brakes, the provided gears can be realized with a very compact design of the bottom bracket gear.

[0010] Within the scope of the present invention, it is provided in the proposed bottom bracket gear that the first switching element, the second switching element and the third switching element are each designed as a positive brake and / or that the fourth switching element and the fifth switching element are each designed as a freewheel.

[0011] The switching elements designed as brakes are preferably designed as positive-locking switching elements, for example, as cost-effective switching claws or the like, for example, with a toothed brake ring and a corresponding switching pawl. Brakes as switching elements have the advantage that they are easily accessible for external operation. Since the provided freewheels are used as clutches, it is advantageous if the brakes are designed, for example, as single-acting brakes to prevent the transmission from jamming when the direction of rotation is reversed at the input or output.

[0012] Non-switchable freewheels are preferably used as freewheels. This has the advantage that no switching operation is required with the passive switching elements. The non-switchable freewheel transmits torque when it is locked. No torque is transmitted in the opposite direction of rotation. However, it is also conceivable that switchable freewheels or switchable freewheel brakes are also used. In the proposed bottom bracket gear, for blocking the third planetary gear set, it can be provided that, within the scope of a first blocking variant, the first element of the third planetary gear set can be connected to the third element of the third planetary gear set via the fifth switching element. Furthermore, within the scope of a second blocking variant, it can be provided that the first element of the third planetary gear set can be connected to the second element of the third planetary gear set via the fifth switching element.It can also be provided within the framework of a third blocking variant that the second element of the third planetary gear set can be connected to the third element of the third planetary gear set via the fifth switching element.

[0013] A preferred embodiment of the invention can provide for at least one of the planetary gear sets to be designed as a negative planetary gear set, resulting in a particularly space-efficient arrangement. It is also conceivable for one of the planetary gear sets to be designed as a positive planetary gear set.

[0014] A negative planetary gear set can be preferably converted into a positive planetary gear set if the planet carrier and ring gear connections on this gear set are swapped and the amount of the stationary gear ratio is increased by 1. A negative planetary gear set has rotatably mounted planet gears on its planet carrier, which mesh with the sun gear and the ring gear of this planetary gear set, so that the ring gear rotates in the opposite direction to the direction of rotation of the sun gear when the planet carrier is held stationary and the sun gear is rotating.A plus planetary gear set has inner and outer planetary gears that are rotatably mounted on its planetary gear carrier and mesh with one another, with the sun gear of this planetary gear set meshing with the inner planetary gears and the ring gear of this planetary gear set meshing with the outer planetary gears, so that the ring gear rotates in the same direction of rotation as the sun gear when the planetary gear carrier is held stationary and the sun gear is rotating.

[0015] For those skilled in the art, this means that in the case of single gear sets designed as a negative planetary gear set, a first element is designed as a sun gear, a second element as a planetary gear carrier or web, and a third element as a ring gear. Furthermore, this means that in a single gear set designed as a positive planetary gear set, the first element is designed as a sun gear, the second element as a ring gear, and the third element as a planetary gear carrier or web.

[0016] In order to further optimize the control of the proposed bottom bracket gear, it is provided that at least one torque sensor or the like is provided on the drive and / or on the output.

[0017] To electrically support the drive in the proposed bottom bracket transmission, at least one electric motor or the like can be connected or connectable to the drive or the pedal crankshaft and / or to the output or the transmission output shaft, or can be permanently or detachably coupled. The electric motor can preferably be arranged axially parallel to the pedal crankshaft.

[0018] A further aspect of the present invention claims a bicycle or pedelec with the above-described bottom bracket gear. This results in the advantages already described and further advantages.

[0019] The present invention is further explained below with reference to the drawings.

[0020] They show:

[0021] Figure 1 is a schematic diagram of a possible design variant of a planetary bottom bracket gear for a bicycle or pedelec;

[0022] Figure 2 shows a schematic principle view of the bottom bracket gear with a first blocking variant for a third planetary gear set;

[0023] Figure 3 shows a schematic principle view of the bottom bracket gearing with a second blocking variant for the third planetary gear set; Figure 4 shows a schematic principle view of the bottom bracket gearing according to Figure 1 with a plus planetary gear set designed as an example as the first planetary gear set;

[0024] Figure 5 is a schematic diagram of the bottom bracket gear according to Figure 1 with a plus planetary gear set designed as a second planetary gear set, for example;

[0025] Figure 6 is a schematic diagram of the bottom bracket gear according to Figure 1 with a plus planetary gear set designed as a third planetary gear set,

[0026] Figure 7 is a schematic view of the bottom bracket gear according to Figure 1 with an exemplary torque sensor on the drive;

[0027] Figure 8 is a schematic view of the bottom bracket gear according to Figure 1 with an electric machine arranged on the drive as an example;

[0028] Figure 9 is a schematic view of the bottom bracket gear according to Figure 1 with an electric machine arranged as an example at the output; and

[0029] Figure 10 is a shifting diagram showing the shiftable gears in the bottom bracket gear according to the invention as shown in Figures 1 to 9.

[0030] Figures 1 to 9 illustrate various embodiments of a planetary bottom bracket gear system according to the invention for a bicycle or pedelec 1, purely by way of example, using schematic diagrams. Figure 1 shows the schematically indicated bicycle or pedelec 1 with the bottom bracket gear system.

[0031] Regardless of the design, the bottom bracket transmission comprises, in a housing or bottom bracket shell 2, a pedal crankshaft or pedal crank Wan as the drive with the pedals and a transmission output shaft Wab as the output with a chain or belt wheel (not shown in detail). Furthermore, four additional shafts W1, W2, W3, W4 are provided, which are coupled or connected to elements of the three planetary gear sets RS1, RS2, RS3. The elements of the first planetary gear set RS1 and the second planetary gear set RS2 as well as the third planetary gear set RS3 are arranged coaxially to the pedal crankshaft Wan. In addition, five shift elements B1, B2, B3, F1, F2, F2', F2" are provided to realize six gears V1, V2, V3, V4, V5, V6. The first shift element B1 and the second shift element B2 as well as the third shift element B3 are each designed as switchable brakes, while the fourth shift element F1 and the fifth shift element F2 are each designed as non-switchable freewheels.

[0032] Furthermore, regardless of the embodiments, the proposed bottom bracket transmission provides that the pedal crankshaft Wan is connected to a second element of the second planetary gear set RS2, wherein the pedal crankshaft Wan is connectable to a first element of the first planetary gear set RS1 via a fourth shifting element F1 and a first shaft W1. Accordingly, when the fourth shifting element F1 is locked, the pedal crankshaft Wan is connected to the first shaft W1.Furthermore, the transmission output shaft Wab is connected to a first element of the second planetary gear set RS2 and to a first element of the third planetary gear set RS3, wherein a second element of the first planetary gear set RS1 is connected via a second shaft W2 to a third element of the second planetary gear set RS2, wherein a third element of the first planetary gear set RS1 is connected via a third shaft W3 to a second element of the third planetary gear set RS3, and wherein, in order to block the third planetary gear set RS3, two elements of the third planetary gear set RS3 can be connected to one another via a fifth shift element F2, F2', F2".

[0033] With the above-described connection of the elements of the planetary gear sets RS1, RS2, RS3 and the shafts Wab, Wab, W1, W2, W3, W4 as well as the switching elements B1, B2, B3, F1, F2, F2', F2", a particularly space-saving design of the bottom bracket gear is achieved.

[0034] In Figures 1 to 3 and 7 to 9, the three planetary gear sets RS1, RS2, RS3 are each designed as space-saving minus planetary gear sets. In this case, the first element of the planetary gear sets RS1, RS2, RS3 is a sun gear SR1, SR2, SR3, the second element is a planetary gear carrier PT1, PT2, PT3, and the third element is a ring gear HR1, HR2, HR3.

[0035] In detail, this means that the pedal crankshaft Wan is connected to the planetary gear carrier PT1 of the second planetary gear set RS2. Furthermore, the pedal crankshaft Wan can be connected to the sun gear SR1 of the first planetary gear set RS1 via the fourth shift element F1, which is designed as a freewheel. The transmission output shaft Wab is connected to the sun gear SR2 of the second planetary gear set RS2 and to the sun gear SR3 of the third planetary gear set RS3. The planetary gear carrier PT1 is connected to the ring gear HR2 of the second planetary gear set RS2 via the second shaft W2. The ring gear HR1 of the first planetary gear set RS1 is connected to the planetary gear carrier PT3 of the third planetary gear set RS3 via the third shaft W3.To block the third planetary gear set RS3, as a first blocking variant, the sun gear SR3 can be connected to the ring gear HR3 of the third planetary gear set RS3 via the fifth switching element F2 designed as a freewheel, or as a second blocking variant, the sun gear SR3 can be connected to the planet gear carrier PT3 via the fifth switching element F2' designed as a freewheel, or as a third blocking variant, the ring gear HR3 can be connected to the planet gear carrier PT3 via the fifth switching element F2" designed as a freewheel.

[0036] Figure 1 shows the first blocking variant, while Figure 2 shows the second blocking variant and Figure 3 shows the third blocking variant. Furthermore, when the first switching element B1 is closed as a brake, the sun gear SR1 of the first planetary gear set RS1 is firmly connected to the housing 2 via the first shaft W1. When the second switching element B2 is closed as a brake, the ring gear HR1 of the first planetary gear set RS1 and the planet gear carrier PT3 of the third planetary gear set RS3 are firmly connected to the housing 2 via the third shaft W3. When the third switching element B3 is closed as a brake, the ring gear HR3 of the third planetary gear set RS3 is firmly connected to the housing 2 via the fourth shaft W4. When the fourth switching element F1 is locked as a freewheel, the pedal crankshaft Wan is connected to the first shaft W1.When the fifth shift element F2 is locked as a freewheel, the transmission output shaft Wab is connected to the fourth shaft W4 and the third planetary gear set RS3 is blocked.

[0037] In Figures 4 to 6, a plus planetary gear set is always provided for the three planetary gear sets RS1, RS2, RS3, whereby the plus planetary gear set has an interchange of the ring gear connection and the planetary gear carrier connection.

[0038] In Figure 4, for example, the first planetary gear set RS1 is designed as a plus planetary gear set, while the second planetary gear set RS2 and the third planetary gear set RS3 are each designed as a minus planetary gear set. In Figure 5, for example, the second planetary gear set RS2 is designed as a plus planetary gear set, while the first planetary gear set RS1 and the third planetary gear set RS3 are each designed as a minus planetary gear set. In Figure 6, for example, the third planetary gear set RS3 is designed as a plus planetary gear set, while the first planetary gear set RS1 and the second planetary gear set RS2 are each designed as a minus planetary gear set. Using a plus planetary gear set results in greater flexibility in the selection of gear ratios.

[0039] Figure 7 shows an embodiment of the bottom bracket transmission according to the invention, in which a torque sensor 3 is connected or connectable to the pedal crankshaft Wan. For example, a disk-shaped torque sensor 3 can be arranged at the transmission input. However, the torque sensor 3 can also be designed in a different way.

[0040] Figures 8 and 9 each show an embodiment of the bottom bracket transmission according to the invention with an additional electric motor EM. The electric motor EM can be connected to the pedal crankshaft Wan, as indicated in Figure 8. It is also conceivable for the electric motor EM to be connected to the transmission output shaft Wab, as shown in Figure 9.

[0041] The electric motor EM is preferably arranged axially parallel to the pedal crankshaft Wan. However, a coaxial arrangement of the electric motor EM to the pedal crankshaft Wan would also be possible. Regardless of this, it is advantageous to connect the electric motor EM via a freewheel or similar device so that, when operating without the electric motor EM, no losses are caused by the co-rotating electric motor EM.

[0042] Figure 10 shows an example of a shifting diagram for the embodiments of the bottom bracket gear according to the invention shown in Figures 1 to 9. The shifting diagram shows the shifting elements B1, B2, B3, F1, F2, F2', F2" used for the respective gear V1, V2, V3, V4, V5, V6. An X for a freewheel F1, F2, F2', F2" as a shifting element in the shifting diagram means that the freewheel is locked. This functions automatically without external actuation. Furthermore, an X for a brake B1, B2, B3 as a shifting element in the shifting diagram means that the brake B1, B2, B3 is closed. This functions via a suitable actuator.

[0043] In detail, the shifting diagram according to Figure 10 shows that to implement a first gear V1, the fourth shifting element F1, designed as a freewheel, and the fifth shifting element F2, F2', F2" designed as a freewheel are locked; to implement a second gear V2, the first shifting element B1, designed as a brake, is closed and the fifth shifting element F2, designed as a freewheel is locked; to implement a third gear V3, the third shifting element B3, designed as a brake, is closed and the fourth shifting element F1, designed as a freewheel is locked; to implement a fourth gear V4, the first shifting element B1, designed as a brake, and the third shifting element B3, designed as a brake, are closed; to implement a fifth gear V5, the second shifting element B2, designed as a brake, is closed and the fourth shifting element F1, designed as a freewheel, is locked.and / or that to achieve a sixth gear V6, the first shifting element B1, designed as a brake, and the second shifting element B2, designed as a brake, are closed. This means that only two shifting elements need to be used simultaneously to shift each gear. Reference numerals,

[0044] 1 bicycle or pedelec

[0045] 2 Housing or bottom bracket shell

[0046] 3 Torque sensor

[0047] SR1 sun gear of the first planetary gear set

[0048] PT 1 planetary gear carrier of the first planetary gear set

[0049] HR1 ring gear of the first planetary gear set

[0050] SR2 sun gear of the second planetary gear set

[0051] PT2 planetary gear carrier of the second planetary gear set

[0052] HR2 ring gear of the second planetary gear set

[0053] SR3 sun gear of the third planetary gear set

[0054] PT3 planetary gear carrier of the third planetary gear set

[0055] HR3 ring gear of the third planetary gear set

[0056] Wan crankshaft

[0057] Wab gearbox output shaft

[0058] EM electric machine

[0059] W1 first wave

[0060] W2 second wave

[0061] W3 third wave

[0062] W4 fourth wave

[0063] RS1 first planetary gear set

[0064] RS2 second planetary gear set

[0065] RS3 third planetary gear set

[0066] B1 first switching element as brake

[0067] B2 second switching element as brake

[0068] B3 third switching element as brake

[0069] F1 fourth switching element as freewheel

[0070] F2,F2',F2“ fifth switching element as freewheel

[0071] V1 first gear

[0072] V2 second gear

[0073] V3 third gear

[0074] V4 fourth gear V5 fifth gear

[0075] V6 sixth gear

Claims

Patent claims 1. A planetary bottom bracket gearbox for a bicycle or pedelec (1), comprising a crankshaft (Wan) as the drive and a gearbox output shaft (Wab) as the output, and at least four further shafts (W1, W2, W3, W4), with three planet gear sets (RS1, RS2, RS3) arranged coaxially to the crankshaft (Wan), and with five shift elements (B1, B2, B3, F1, F2, F2', F2") for realizing at least six gears (V1, V2, V3, V4, V5, V6), wherein the crankshaft (Wan) is connected to a second element of the second planet gear set (RS2), wherein the crankshaft (Wan) can be connected to a first element of the first planet gear set (RS1) via a fourth shift element (F1) and a first shaft (W1), and wherein the gearbox output shaft (Wab) is connected to a first element of the second planetary gear set (RS2) and is connected to a first element of the third planetary gear set (RS3),wherein a second element of the first planetary gear set (RS1) is connected via a second shaft (W2) to a third element of the second planetary gear set (RS2), wherein a third element of the first planetary gear set (RS1) is connected via a third shaft (W3) to a second element of the third planetary gear set (RS3), and wherein, for locking the third planetary gear set (RS3), two elements of the third planetary gear set (RS3) can be connected to each other via a fifth switching element (F2, F2', F2").

2. Bottom bracket gearbox according to claim 1, characterized in that when the first switching element (B1) is closed, the first shaft (W1) connected to the first element of the first planetary gear set (RS1) is fixedly connected to a housing (2), that when the second switching element (B2) is closed, the third shaft (W3) connected to the third element of the first planetary gear set (RS1) and to the second element of the third planetary gear set (RS3) is fixedly connected to the housing (2), and that when the third switching element (B3) is closed, a fourth shaft (W4) connected to the third element of the third planetary gear set (RS3) is fixedly connected to the housing (2).

3. Bottom bracket gearbox according to one of the preceding claims, characterized in that the first switching element (B1), the second switching element (B2) and the third switching element (B3) are each designed as a positive-locking brake. and / or that the fourth switching element (F1 ) and the fifth switching element (F2, F2', F2“) are each designed as a freewheel.

4. Bottom bracket gearbox according to one of the preceding claims, characterized in that a torque sensor (3) is connected to the pedal crank shaft (Wan).

5. Bottom bracket gearbox according to one of the preceding claims, characterized in that at least one electric machine (EM) is connected or connectable to the pedal crank shaft (Wan) or to the gearbox output shaft (Wab).

6. Bottom bracket gearbox according to claim 5, characterized in that the electric machine (EM) is arranged parallel to the crankshaft (Wan).

7. Bottom bracket gearbox according to one of the preceding claims, characterized in that, for locking the third planetary gear set (RS3), the first element of the third planetary gear set (RS3) can be connected to the third element of the third planetary gear set (RS3) via the fifth switching element (F2).

8. Bottom bracket gearbox according to one of claims 1 to 6, characterized in that, for locking the third planetary gear set (RS3), the first element of the third planetary gear set (RS3) can be connected to the second element of the third planetary gear set (RS3) via the fifth switching element (F2').

9. Bottom bracket gearbox according to one of claims 1 to 6, characterized in that, for locking the third planetary gear set (RS3), the second element of the third planetary gear set (RS3) can be connected to the third element of the third planetary gear set (RS3) via the fifth switching element (F2").

10. Bottom bracket gearbox according to one of the preceding claims, characterized in that at least one of the planetary gear sets (RS1 , RS2, RS3) is designed as a negative planetary gear set.

11. Bottom bracket gear according to claim 10, characterized in that in a minus planetary gear set the first element is designed as a sun gear (SR1 , SR2, SR3), the second element as a planet carrier (PT1 , PT2, PT3) and the third element as a ring gear (HR1 , HR2, HR3).

12. Bottom bracket gearbox according to one of the preceding claims, characterized in that at least one of the planetary gear sets (RS1 , RS2, RS3) is designed as a plus planetary gear set.

13. Bottom bracket gearbox according to claim 12, characterized in that in a plus planetary gear set the first element is designed as a sun gear (SR1 , SR2, SR3), the second element as a ring gear (HR1 , HR2, HR3) and the third element as a planet carrier (PT1 , PT2, PT3).

14. Bottom bracket gearbox according to one of the preceding claims, characterized in that, to realize a first gear (V1), the fourth shifting element (F1) designed as a freewheel and the fifth shifting element (F2, F2', F2") designed as a freewheel are locked, that, to realize a second gear (V2), the first shifting element (B1) designed as a brake is closed and the fifth shifting element (F2) designed as a freewheel is locked, that, to realize a third gear (V3), the third shifting element (B3) designed as a brake is closed and the fourth shifting element (F1) designed as a freewheel is locked, that, to realize a fourth gear (V4), the first shifting element (B1) designed as a brake and the third shifting element (B3) designed as a brake are closed,that to implement a fifth gear (V5), the second shift element (B2) designed as a brake is closed and the fourth shift element (F1) designed as a freewheel is locked, and / or that to implement a sixth gear (V6), the first shift element (B1) designed as a brake and the second shift element (B2) designed as a brake are closed.

15. Bicycle or pedelec (1 ) with the bottom bracket gearbox according to one of the preceding claims.

Images