Planetary Bicycle Gearbox Assembly With Three Ratios in One Gear Set
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Solution Overview
Problem
Existing bicycle gearboxes with planetary designs often require additional planetary gear sets to provide more gears, which increases complexity, cost, and space requirements.
Innovation Solution
A gear set arrangement for a planetary gearbox that includes a stationary component, brakes, and freewheel clutches, allowing for three distinct gear ratios without the need for additional planetary gear sets, by utilizing a single planetary gear set and strategically actuating the brakes and freewheel clutches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional planetary gear sets are used to provide more gears, then the number of transmission gears increases, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by enabling a single planetary gear set to perform multiple gear ratio functions through the coordinated use of two brakes and two freewheel clutches. Instead of requiring separate planetary gear sets for each gear ratio, this mechanism allows one planetary assembly to provide three distinct gear ratios (first, second, and third ratios) by selectively engaging different brake and clutch combinations, thereby reducing overall device complexity while maintaining gear variety
Solution Approach 2:
The patent employs dynamics by using actively actuable brakes and automatically actuable freewheel clutches that can dynamically change the operational state of the planetary gear set. The brakes can be actively engaged or disengaged to fix or release rotary elements, while the freewheel clutches automatically engage or disengage based on rotation direction, allowing the system to dynamically switch between different gear ratios without mechanical reconfiguration
2Adaptability or versatility
If additional planetary gear sets are used to provide more gears, then the number of transmission gears increases, but the cost increases
Solution Approach 1:
The patent reduces manufacturing cost by making the single planetary gear set universal for providing multiple gear ratios. Instead of manufacturing and assembling multiple separate planetary gear sets, the invention uses one planetary assembly with added control mechanisms (two brakes and two freewheel clutches) that can deliver three different gear ratios, thereby reducing material costs, assembly costs, and overall manufacturing complexity
3Adaptability or versatility
If additional planetary gear sets are used to provide more gears, then the number of transmission gears increases, but the space requirements increase
Solution Approach 1:
The patent applies the nesting principle by integrating the brakes and freewheel clutches within the same planetary gear set structure. The two brakes and two freewheel clutches are arranged to work within the compact space of a single planetary assembly, allowing multiple gear ratios to be achieved without increasing the overall volume. This nested arrangement eliminates the need for additional space that would be required for separate planetary gear sets
4Adaptability or versatility
If additional planetary gear sets are used to provide more gears, then the number of transmission gears increases, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by enabling a single planetary gear set to perform multiple gear ratio functions through the coordinated use of two brakes and two freewheel clutches. Instead of requiring separate planetary gear sets for each gear ratio, this mechanism allows one planetary assembly to provide three distinct gear ratios (first, second, and third ratios) by selectively engaging different brake and clutch combinations, thereby reducing overall device complexity while maintaining gear variety
Solution Approach 2:
The patent employs dynamics by using actively actuable brakes and automatically actuable freewheel clutches that can dynamically change the operational state of the planetary gear set. The brakes can be actively engaged or disengaged to fix or release rotary elements, while the freewheel clutches automatically engage or disengage based on rotation direction, allowing the system to dynamically switch between different gear ratios without mechanical reconfiguration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for a compact and efficient gearbox design that provides three gear ratios with reduced complexity and cost, while maintaining a compact form factor suitable for both front and rear-mounted applications.
Implementation Method 1
A brake can be an interlocking or friction-locking shift element. The respective brakes can be designed to prevent rotation of a rotary element connected thereto, or to reduce the rotation thereof
Implementation Method 2
A freewheel clutch can be a clutch acting in only one direction of rotation. Two elements which are connectable to each other for conjoint rotation by a freewheel clutch are permanently connected to each other for conjoint rotation in one direction of rotation of these two elements relative to each other
Data Source
AI summary
A gear set arrangement (10) for a bicycle gearbox (400) includes a planetary assembly, a stationary component (24), a first and a second brake (B1, B2), and a first and a second freewheel clutch (F1, F2). One planetary gear set (12) of the planetary assembly includes a first rotary element, a second rotary element, and a third rotary element. The first rotary element is rotationally fixable on the stationary component (24) by the first brake (B1). The first rotary element is connectable to the output (36) by the first freewheel clutch (F1). The second rotary element is rotationally fixable on the stationary component (24) by the second brake (B2). The second rotary element is connectable to the output (36) by the second freewheel clutch (F2). The third rotary element is connected to the input (34) for conjoint rotation. The gear set arrangement (10) is configured to provide three ratios.