Bottom bracket gearing system with an arrangement for actuating a brake shift element
Patent Information
- Application Number
- EP2024700608
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-01-17
- Filing Date
- 2024-01-12
- Publication Date
- 2025-11-26
Smart Images
Figure EP2024050676_25072024_PF_FP_ABST
Abstract
Description
[0001] ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 Bottom bracket gear with an arrangement for actuating a brake shifting element The present invention relates to a bottom bracket gear in planetary gear set design for a bicycle with an arrangement for actuating a brake shifting element. Furthermore, the invention relates to a bicycle with the bottom bracket gear. For example, from the document DE 102019220044 A1, a bottom bracket gear with an arrangement for actuating a shifting element is known. The arrangement comprises a rotatably arranged shift drum, wherein the shift drum has several curved tracks axially adjacent to one another for the sequential actuation of several brake pawls of the brake shifting elements, so that only a sequential shifting of gears is possible in the bottom bracket gear. Accordingly, the shifts from the engaged gear to the target gear take place sequentially in a fixed order, i.e., no gears can be skipped, which increases the shifting time. The present invention is based on the object of proposing a bottom bracket gear and a vehicle with the bottom bracket gear which, in addition to sequential shifts, also enable direct shifts for skipping gear steps. This object is achieved according to the invention by the features of patent claims 1 and 11 respectively. Advantageous and claimed further developments emerge from the subclaims and the description as well as the drawings. Thus, a bottom bracket gear in planetary gear set design for a bicycle is proposed, having an arrangement for actuating a brake pawl of a brake shifting element for locking and releasing a transmission component for shifting a gear step.In order to enable direct shifting for skipping gear steps in addition to sequential shifting, each brake pawl is operatively connected to a separately controllable, rotatable cam element. ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 The bicycle is preferably designed as an (S-)Pedelec, e-bike, velomobile, cargo bike, or the like. The bicycle preferably has an electric (auxiliary) drive. In this way, decentralized actuation orActuation of brake shifting elements of the bottom bracket gear by the separately controllable cam elements in such a way that not only sequential shifting of successive gear steps, but also direct shifting to any gear step is possible due to the cam elements assigned to each brake pawl, so that any desired target gear can be engaged directly in any shifting sequence, regardless of the currently engaged gear. The brake pawl can preferably be designed as a spring-loaded rocker arm, wherein a first rocker arm is assigned to a locking toothing of the gear component and wherein a second rocker arm is assigned to a curved path provided on the circumference of the separately controllable cam element for actuating the brake pawl. The brake pawl is preferably designed as a normally closed brake pawl. This means that the spring-loaded rocker arm with its pawl tip orwith its pawl hook on the first rocker arm, is pressed by spring force into the locking teeth of the transmission component to be locked, such as a planetary gear carrier, a sun gear, or a ring gear of the bottom bracket gear, in order to block or secure the transmission component so that the associated gear can be shifted. In order to minimize friction at the contact surface between the brake pawl and the cam element in the bottom bracket gear that enables direct shifting in any shifting sequence, a rotatable roller or the like can be provided, for example, on the second rocker arm of the brake pawl as a contact surface with the circumference of the cam element. Preferably, a pivot axis of each brake pawl and a rotation axis of each cam element are arranged approximately axially parallel to a central bottom bracket gear rotation axis.In this way, the required components for the bottom bracket gear proposed by ZF Friedrichshafen AG (file 215040 Friedrichshafen, 2023-01-17) can be integrated into the existing bottom bracket shell, enabling both sequential and direct shifting without the need for an additional housing. For particularly simple control of each cam element, it can be provided, for example, that each cam element is assigned a rotary drive, for example, an electric servomotor or the like. To control each cam element, it is only necessary for the cam element to be rotated in one direction. The rotary movement of each rotary drive can be transmitted, for example, to the associated cam element via a high-ratio reduction gear.A particularly compact and cost-effective reduction gear can be realized by using several interconnected planetary gear sets or the like as the reduction gear. To actuate each brake pawl by the associated cam element, a curved path can be provided along the circumference of each cam element, with a first, shorter ramp section with a greater pitch for quickly engaging the brake pawl in the locking teeth of the associated gear component, and with a second, longer ramp section with a lower pitch for disengaging the switching pawl with a low load.In this way, the steep ramp section releases and accelerates the spring-loaded engagement of the brake pawl through a short rotary movement of the cam element, while the flatter, longer ramp section enables the disengagement of the brake pawl with the lowest possible load through a longer rotary movement of the cam element. Consequently, the rotary drive of the cam element can be dimensioned accordingly small. To simplify the control when performing direct gear shifts in the proposed bottom bracket transmission, the rotatable cam element is assigned a position detection function. In this way, the gear shift control knows the position of each cam element at all times.ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 The object underlying the invention is also achieved by a bicycle with the above-described bottom bracket gear, resulting in the advantages already described and others. The present invention is further explained below with reference to the drawings.Shown are: Figure 1: a schematic side view of a bottom bracket gear mechanism of a bicycle according to the invention, with a cam element for actuating a brake pawl of a brake switching element; Figure 2: a schematic partial view of a gear section through the bottom bracket gear mechanism according to the invention; Figure 3: a schematic side view of the bottom bracket gear mechanism with multiple cam elements for actuating multiple brake pawls; Figure 4: a schematic side view of the bottom bracket gear mechanism with multiple cam elements for actuating multiple brake pawls in an alternative arrangement position; Figure 5: a gear section through the bottom bracket gear mechanism according to the invention, with multiple cam elements for actuating multiple brake pawls; Figure 6: a schematic schematic diagram of the bottom bracket gear mechanism; and Figure 7: a circuit diagram of the brake switching elements and the freewheel clutches of the bottom bracket gear mechanism according to Figures 5 and 6.ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 Figures 1 to 6 show various views of a bottom bracket gear train in a planetary gear set design for a bicycle 1, designed as a pedelec, with one or more rotatable cam elements 2, 3, 4, 5 as an arrangement for separately actuating one or more brake pawls 6, 7, 8, 9 of brake switching elements B1, B2, B3, B4. Figure 7 shows a circuit diagram for the brake switching elements B1, B2, B3, B4 and freewheel clutches F1, F2, F3, F4 of the bottom bracket gear train, which is designed as a 16-speed transmission only as an example. A brake switching element B1, B2, B3, B4 is generally understood to be an actuatable brake which fixes a transmission component in the closed state or connects it to a housing 10 of the bottom bracket transmission.By way of example, a bottom bracket gear mechanism in planetary gear set design with several, preferably four planetary gear sets RS1, RS2, RS3, RS4 for a bicycle 1 with the cam elements 2, 3, 4, 5 for actuating at least one of the brake switching elements B1, B2, B3, B4 is proposed, which is shown in detail in Figures 5 and 6. Accordingly, the bottom bracket gear mechanism comprises, as an arrangement for actuating the four brake pawls 6, 7, 8, 9 of the four brake switching elements B1, B2, B3, B4, the four separately controllable cam elements 2, 3, 4, 5 for locking and releasing a gear component for switching any gear G1 to G16, regardless of the gear engaged at a time. Figure 1 shows, by way of example, a fourth cam element 5 for actuating a fourth brake pawl 9 of a fourth brake switching element B4.Each brake pawl 6, 7, 8, 9 is designed as a spring-loaded rocker arm, with a first rocker arm being assigned to a locking toothing 11 of the respective transmission component and a second rocker arm being assigned to a curved track 12, 13, 14, 15 provided on the circumference of the separately controllable cam element 2, 3, 4, 5. The curved track 12, 13, 14, 15 on each cam element 2, 3, 4, 5 has a first shorter ramp section with a greater gradient for quickly engaging the brake pawl and a second longer ramp section with a lower gradient for disengaging the brake pawl from the locking toothing of the transmission component assigned to it. ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17The specifications for shorter and longer ramp sections relate to the rotational angle range of the cam element 2, 3, 4, 5, so that the first ramp section extends over a smaller rotational angle range and the second ramp section over a larger rotational angle range. Each cam element 2, 3, 4, 5 has its own rotary drive 16 for separate control, which is operatively connected to the respective cam element 2, 3, 4, 5 via a reduction gear 17 consisting of several interconnected planetary gear sets in order to rotate the cam element 2, 3, 4, 5, for example, counterclockwise. In Figure 1, the brake pawl 9 of the fourth brake switching element B4 is in the disengaged state, since the second rocker arm of the brake pawl 9 is located on the second ramp section of the curved path 15 of the cam element 5 shortly before the first steep ramp section of the curved path 15.As a result, the brake pawl 15 is held against the spring force in a position in which the first rocker arm is not engaged with the locking teeth 11. When the cam element 5 is rotated further by the associated rotary drive 16, the brake pawl 9 is released due to the steep ramp section and can engage with the locking teeth 11 due to the spring force. Figure 2 shows an example of the rotary drive 16 with the reduction gear 17 using the fourth cam element 5 for actuating the fourth brake pawl 9 of the fourth brake switching element B4.The reduction gear 17 consists, for example, of four planetary gear sets, wherein the rotary drive is coupled to the reduction gear via a sun gear, while the ring gears of the planetary gear sets are fixed to the housing 10 and the planet gear carriers of the planetary gear sets are each coupled to the sun gear of the adjacent planetary gear set, wherein the planet gear carrier of the last planetary gear set is connected to the cam element 5 for the drive. As can be seen, for example, from Figures 3, 4 and 5, the pivot axes of the brake pawls 6, 7, 8, 9 and the rotation axes of the cam elements 2, 3, 4, 5 ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 are arranged approximately axially parallel to a central bottom bracket gear rotation axis 18. Figure 3 shows an arrangement position of the cam elements 2, 3, 4, 5 and the brake pawls 6, 7, 8, 9 in a common area of the housing 10.Figure 4 shows an alternative arrangement position of the cam elements and the brake pawls in separate areas of the housing on the circumference of the bottom bracket gear. Regardless of the arrangement position, the first brake pawl 6 and the third brake pawl 8 are assigned to a common bolt with a common pivot axis, while the second brake pawl 7 and the fourth brake pawl 9 are also assigned to a common bolt with a common pivot axis.Figures 3, 4 and 5 show that the first brake pawl 6 of the first brake switching element B1 is assigned the first separately controllable cam element 2, the second brake pawl 7 of the second brake switching element B2 is assigned the second separately controllable cam element 3, the third brake pawl 8 of the third brake switching element B3 is assigned the third separately controllable cam element 4, and the fourth brake pawl 9 of the fourth brake switching element B4 is assigned the fourth separately controllable cam element 5. Figure 6 shows a schematic representation of the bottom bracket gear with the four planetary gear sets RS1, RS2, RS3, RS4. To implement the 16 gear stages G1 to G16, four brakes B1, B2, B3, B4 and four freewheel clutches F1, F2, F3, F4 are assigned to the planetary gear sets RS1, RS2, RS3, and RS4. The transmission design, which is known per se, will not be described further, as it will be obvious to the expert.The corresponding shift pattern of the bottom bracket transmission shown in Figures 5 and 6 is shown in Figure 7. In the shift pattern shown in Figure 7, a line for the brake shift elements B1, B2, B3, B4 indicates an open state, i.e., a release of the associated transmission component, while a point in the shift pattern corresponds to the closed state of the brake shift elements B1, B2, B3, B4. ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 For the one-way clutches F1, F2, F3, F4, a line in the shift pattern for implementing the respective gear stage G1 to G16 indicates the overrunning drive state, while a point in the shift pattern for implementing the corresponding gear stage G1 to G16 indicates the locked state.A direct, non-sequential shift in any order to a desired target gear G1 to G16 can be triggered by appropriately controlling the respective cam element 2, 3, 4, 5, so that, for example, shifts from the fifteenth gear G15 to the fifth gear G5 or similar are possible. With the bottom bracket gear according to the invention, it is possible, for example, for a user to individually determine the number of gears. Particularly with a gear system with a high number of gears and uniform gradation, the user has the option of deliberately omitting individual gears in order to be able to represent large or small gear steps with the same basic gear system.
[0002] ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 Reference numeral 1 Bicycle 2 First cam element 3 Second cam element 4 Third cam element 5 Fourth cam element 6 First brake pawl 7 Second brake pawl 8 Third brake pawl 9 Fourth brake pawl 10 Housing or bottom bracket housing 11 Locking toothing 12 Cam track of the first cam element 13 Cam track of the second cam element 14 Cam track of the third cam element 15 Cam track of the fourth cam element 16 Rotary drive 17 Reduction gear 18 Central bottom bracket gear rotation axis RS1 Planetary gear set RS2 Planetary gear set RS3 Planetary gear set RS4 Planetary gear set G1 to G16 16 gear stages B1 First brake switching element B2 Second brake switching element B3 Third brake switching element B4 Fourth brake switching element F1 First overrunning clutch F2 Second One-way clutch F3 third one-way clutch F4 fourth one-way clutch
Claims
ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 Patent claims 1. Bottom bracket transmission in planetary gear set design for a bicycle (1), with an arrangement for actuating a brake pawl (6, 7, 8, 9) of a brake switching element (B1, B2, B3, B4) for locking and releasing a transmission component for switching a gear stage (G1 to G16), characterized in that each brake pawl (6, 7, 8, 9) is in operative connection with a separately controllable rotatable cam element (2, 3, 4, 5).
2. Bottom bracket transmission according to claim 1, characterized in that the brake pawl (6, 7, 8, 9) is designed as a spring-loaded rocker arm, wherein a first rocker arm is assigned to a locking toothing (11) of the transmission component and wherein a second rocker arm is assigned to a curved track (12, 13, 14, 15) provided on the circumference of the separately controllable cam element (2, 3, 4, 5) for actuating the brake pawl (6, 7, 8, 9).Bottom bracket gear according to claim 2, characterized in that a rotatable roller is provided on the second rocker arm of the brake pawl (6, 7, 8, 9) as a contact surface with the curved path (12, 13, 14, 15) of the cam element (2, 3, 4, 5).
4. Bottom bracket gear according to one of the preceding claims, characterized in that a pivot axis of each brake pawl (6, 7, 8, 9) and a rotation axis of each cam element (2, 3, 4, 5) are arranged approximately axially parallel to a central bottom bracket gear rotation axis (18).
5. Bottom bracket gear according to one of the preceding claims, characterized in that each cam element (2, 3, 4, 5) is assigned a rotary drive (16) for separate control.
6. Bottom bracket gear according to claim 5, characterized in that the rotary movement of the rotary drive (16) can be transmitted to the associated cam element (2, 3, 4, 5) via a reduction gear (17). ZF Friedrichshafen AG File 215040 Friedrichshafen 2023-01-17 7. Bottom bracket gear according to claim 6, characterized in that a plurality of interconnected planetary gear sets are provided as the reduction gear (17).
8. Bottom bracket gear according to one of the preceding claims, characterized in that a curved path (12, 13, 14, 15) is provided along the circumference of the cam element (2, 3, 4, 5) with a first, shorter ramp section with a greater gradient for quickly engaging the brake pawl (6, 7, 8, 9) and with a longer ramp section with a smaller gradient for disengaging the brake pawl (6, 7, 8, 9) from the locking toothing of the associated gear component.
9. Bottom bracket gear according to one of the preceding claims, characterized in that the rotatable cam element (2, 3, 4, 5) is assigned a position detection device. 10.Bottom bracket gear according to one of the preceding claims, characterized in that a first separately controllable cam element (2) is assigned to a first brake pawl (6) of a first brake switching element (B1), that a second separately controllable cam element (3) is assigned to a second brake pawl (7) of a second brake switching element (B2), that a third separately controllable cam element (4) is assigned to a third brake pawl (8) of a third brake switching element (B3), and that a fourth separately controllable cam element (5) is assigned to a fourth brake pawl (9) of a fourth brake switching element (B4).
11. Bicycle (1) with a bottom bracket gear according to one of the preceding claims.