US-12623753-B2 - System and method for changing a bicycle transmission ratio of a bicycle transmission

US12623753B2US 12623753 B2US12623753 B2US 12623753B2US-12623753-B2

Abstract

Disclosed is a bicycle transmission ratio changing system comprising bicycle transmission, and a control unit configured to change the bicycle transmission according to an shift sequence. The shift sequence includes a synchronous shift step of synchronously changing the transmission ratio of a first transmission and the transmission ratio of a second transmission; and a non-synchronous shift step of selectively changing either the transmission ratio of the first transmission or the transmission ratio of the second transmission. The shift sequence includes at least the lower of Nor M−1 synchronous shift steps, wherein N corresponds to the number of different transmission ratios of the first transmission and M corresponds to the number of different transmission ratios of the second transmission.

Inventors

Roëll Marie Van Druten

Assignees

CLASSIFIED CYCLING BV

Dates

Publication Date: 20260512
Application Date: 20220628
Priority Date: 20210628

Claims (20)

1 . A bicycle transmission ratio changing system comprising: a first transmission selectively operable according to one of N different transmission ratios, N being at least two; a second transmission selectively operable according to M different transmission ratios, M being at least three, M being larger than N; wherein the first transmission is connected to the second transmission to form, together, a bicycle transmission which is operable according to a plurality of bicycle transmission ratios; and a control unit configured to receive a first shift signal for upshifting or downshifting a bicycle transmission ratio to a next higher or next lower bicycle transmission ratio, and, in response to receiving the first shift signal, change a transmission ratio of the first transmission and/or change a transmission ratio of the second transmission so as to upshift or downshift the bicycle transmission ratio to the next higher or next lower bicycle transmission ratio, wherein the control unit is configured to upshift and/or downshift the bicycle transmission ratio to the next higher or next lower bicycle transmission ratio according to an upshift sequence through the bicycle transmission ratios, and/or a downshift sequence through the bicycle transmission ratios, and wherein the upshift sequence and/or downshift sequence includes synchronous shift steps and non-synchronous shift steps, wherein the non-synchronous upshift steps in the upshift sequence include maintaining the transmission ratio of the second transmission and upshifting the transmission ratio of the first transmission, and wherein the synchronous upshift steps in the upshift sequence include synchronously upshifting the transmission ratio of the second transmission and downshifting the transmission ratio of the first transmission, wherein, in the upshift sequence and/or in the downshift sequence, the transmission ratios of the second transmission are traversed in a descending or ascending order only, wherein the upshift sequence includes at least the lower of N or M−1 synchronous shift steps, and/or the downshift sequence includes at least the lower of N or M−1 synchronous shift steps.
2 . The system of claim 1 , wherein the downshift sequence is configured such that in the downshift sequence, at least one of the synchronous shift steps includes at least one upshift of the transmission ratio of the first transmission.
3 . The system of claim 1 , wherein the upshift sequence and/or the downshift sequence is configured such that consecutive bicycle transmission ratios include alternatingly the synchronous shift step and the non-synchronous shift step, or vice versa.
4 . The system of claim 1 , wherein the upshift sequence and/or the downshift sequence is configured such that consecutive bicycle transmission ratios are formed by alternatingly a synchronous shift step and a non-synchronous shift step.
5 . The system of claim 1 , wherein the upshift sequence and/or the downshift sequence is configured such that consecutive bicycle transmission ratios includes non-alternatingly the synchronous shift step and the non-synchronous shift step.
6 . The system of claim 5 , wherein the upshift sequence and/or the downshift sequence is configured such that consecutive bicycle transmission ratios includes a synchronous shift step directly followed by at least two consecutive non-synchronous shift steps, or wherein the upshift sequence and/or the downshift sequence is configured such that consecutive bicycle transmission ratios includes a non-synchronous shift step directly followed by at least two consecutive synchronous shift steps.
7 . The system of claim 1 , wherein the synchronous shift step includes upshifting or downshifting the transmission ratio of the second transmission to at most a second-next higher or second-next lower transmission ratio, preferably to at most a next higher or next lower transmission ratio.
8 . The system of claim 1 , wherein the upshift sequence and/or the downshift sequence contains all bicycle transmission ratios.
9 . The system of claim 1 , wherein the upshift sequence and the downshift sequence are equal and opposite.
10 . The system of claim 1 , wherein all of the bicycle transmission ratios differ from one another by at least 5%.
11 . The system of claim 1 , wherein, the upshift sequence is configured such that the transmission ratios of the second transmission are traversed in an ascending order only and/or wherein, the downshift sequence is configured such that the transmission ratios of the second transmission are traversed in a descending order only.
12 . The system of claim 1 , wherein the upshift sequence and/or the downshift sequence is configured to be alternatingly a synchronous shift step and a non-synchronous shift step.
13 . The system of claim 1 , wherein the upshift sequence and/or the downshift sequence is not alternatingly a synchronous shift step and a non-synchronous shift step.
14 . The system of claim 1 , wherein the first transmission is housed at a crank or at a wheel hub.
15 . The system of claim 1 , wherein the first transmission is a continuously variable transmission.
16 . The system of claim 1 , wherein the first transmission includes at least a 1:1 transmission ratio.
17 . The system of claim 1 , wherein the first transmission includes at least one speed increasing or speed decreasing transmission ratio.
18 . The system of claim 1 , wherein the second transmission includes a set of sprockets of varying sizes or a cassette.
19 . The system of claim 1 , further comprising an operating device arranged for transmitting a shift signal for changing the bicycle transmission ratio to a second-next higher or second-next lower bicycle transmission ratio, and wherein the control unit is configured to receive the shift signal, and, in response to receiving the shift signal, change the transmission ratio of the first transmission and/or change the transmission ratio of the second transmission so as to upshift or downshift the bicycle transmission ratio to the second-next higher or second-next lower bicycle transmission ratio, wherein the control unit is configured to: upshift and/or downshift the bicycle transmission ratio to the second-next higher or second-next next lower bicycle transmission ratio according to an even shift sequence through the even bicycle transmission ratios, and/or upshift and/or downshift the bicycle transmission ratio to the second-next higher or second-next lower bicycle transmission ratio according to an odd shift sequence through the odd bicycle transmission ratios, wherein the even and/or odd shift sequence includes the synchronous shift step of synchronously changing the transmission ratio of the first transmission and the transmission ratio of the second transmission; and/or the non-synchronous shift step of selectively changing either the transmission ratio of the first transmission or the transmission ratio of the second transmission.
20 . A bicycle comprising a bicycle transmission changing system according to claim 1 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the national stage entry of PCT/EP2022/067767, filed Jun. 28, 2022, which claims priority to Netherlands Application No. 2028558, filed Jun. 28, 2021, the entire contents of each of which are herein incorporated by reference in their entireties. FIELD The invention relates to a system and method for changing a bicycle transmission ratio of a bicycle transmission. BACKGROUND Known bicycle transmissions, particularly race bicycles, include at least two front chainwheels coupled to an input, such as a crank, and a set of rear sprockets coupled to an output, typically a rear wheel of the bicycle. The front chainwheels are coupled to the rear sprockets via a chain, which selectively meshes with any one of the chainwheels and any one of the sprockets to obtain various bicycle transmission ratios between the input and the output. A front derailleur is arranged to switch the chain from one chainwheel to another, and a rear derailleur is arranged to switch the chain from one sprocket to another. An operating device, typically provided at a handlebar of the bicycle, allows the user to command a transmission ratio change by sending shift signals to the front derailleur and/or the rear derailleur. In conventional systems, the front and rear derailleur are independently operated by means of separate shift signals. For instance, a left hand shifter only operates the front derailleur, and a right hand shifter only operates the rear derailleur. More modern systems include a control unit which can operate both the front and rear derailleurs simultaneously upon receiving a shift signal from the operating device. A control unit may contain an upshift sequence and a downshift sequence, each including a synchronous shift step at which the front and rear derailleurs are operated simultaneously upon receiving a single shift signal. At an upshift synchronous shift step, the front derailleur shifts the chain to a larger chainwheel while the rear derailleur simultaneously shifts the chain to a larger sprocket, causing a resultant increase in the bicycle transmission ratio. At a downshift synchronous shift step, the front derailleur shifts the chain to a smaller chainwheel while the rear derailleur simultaneously shifts the chain to a smaller sprocket, causing a resultant decrease in the bicycle transmission ratio. A downside of these known modern systems is that each synchronous shift step causes a considerable downtime in which substantially no torque can be transmitted by the bicycle transmission. This downtime is particularly due to the shifting of the chain from one chainwheel to another, which is typically a large jump in bicycle transmission ratio. A large jump between front chain rings is often required for obtaining a sufficiently broad range of bicycle transmission ratios. Hence, to avoid shifting with the front derailleur, the known systems keep the number of synchronous shift steps to a bare minimum, wherein, as a result, many bicycle transmission ratios remain unused. SUMMARY It is an aim to provide an improved bicycle transmission ratio changing system and method. It is particularly an aim to provide an effective range of bicycle transmission ratios, and make efficient use thereof. It is also an aim to provide a system and method for efficient and user-friendly shifting through the transmission ratios of the bicycle. According to a first aspect is provided a bicycle transmission ratio changing system comprising a first transmission selectively operable according to one of at least two different transmission ratios, e.g. exactly two. The system may comprise a first actuator for switching the first transmission between the at least two transmission ratios. The first transmission may for example be embodied as a hub transmission housed in a, e.g. a rear, wheel hub of the bicycle. The first transmission may also be embodied as a crank transmission, housed at a crank of the bicycle. The first transmission may include a planetary gear set with at least three rotational members, such as a sun gear, a planet carrier and a ring gear. A clutch system can be used for selectively coupling two of the rotational members, e.g. the planet carrier and the ring gear. When coupled, the hub gear shifting mechanism operates e.g. according to a first gear ratio, and when decoupled according to a second gear ratio. Alternatively, or additionally, the first transmission, can be embodied as a continuously variable transmission, CVT, which is e.g. operated in certain, programmable, gear ratios. In this case the first actuator can be a CVT ratio actuator. The system further comprises a second transmission selectively operable according to one of at least two transmission ratios. The second transmission may for example comprise a chainwheel, a set of sprockets of varying sizes and a chain for meshing with the chainwheel and for selectively meshing with any one of the sprockets to operate