Bicycle Automatic Transmission Planetary Gear Shifting
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Solution Overview
Problem
Conventional bicycle transmissions face difficulties in performing rapid and smooth gearshifting from low speed to high speed or vice versa, requiring excessive driving energy, especially on uphill roads.
Innovation Solution
An automatic transmission system for bicycles, comprising a shifting unit with a ring gear, sun gear, planetary gears, and a regulation unit that controls the connection between the drive unit and the wheel, allowing for seamless gear changes by rotating the ring gear, sun gear, or both, to adjust rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional bicycle transmission is used, then the structure is simple, but rapid and smooth gearshifting cannot be achieved
Solution Approach 1:
The patent employs a planetary gear mechanism where planetary gears are nested within the ring gear and engage with the sun gear. This nested configuration allows multiple gear ratios to be achieved within a compact structure, enabling rapid gearshifting without significantly increasing overall device complexity. The planetary gears can be selectively engaged to provide different transmission ratios, solving the contradiction between fast gearshifting and structural simplicity.
Solution Approach 2:
The transmission system incorporates a dynamic shifting mechanism that can rapidly change gear ratios during operation. The regulation unit dynamically adjusts the engagement of planetary gears with the sun gear and ring gear, allowing smooth transitions between different speeds. This dynamic capability enables rapid gearshifting while maintaining a relatively simple base structure that only becomes complex during active gear changes.
2Use of energy by moving object
If a fixed crankshaft distance is used, then the structure is simple, but greater driving energy is required on uphill roads
Solution Approach 1:
The patent changes the transmission ratio parameter dynamically through the planetary gear mechanism. By varying the engagement of planetary gears with the sun gear and ring gear, the system can provide higher torque multiplication for uphill conditions, reducing the driving energy required from the pedals. This parameter change capability allows the same simple crankshaft structure to operate efficiently across different terrain conditions.
Solution Approach 2:
The planetary gear transmission provides multiple functions within a single mechanism: it can operate in direct drive mode for flat terrain and in gear multiplication mode for uphill conditions. This multi-functionality allows the transmission system to reduce driving energy requirements across various operating conditions without requiring multiple separate crankshaft mechanisms, thereby limiting the increase in structural complexity.
3Ease of operation
If conventional gearshifting is used, then the structure is simple, but smooth gearshifting from low speed to high speed cannot be achieved
Solution Approach 1:
The patent introduces a regulation unit as an intermediary mechanism that controls the engagement and disengagement of the planetary gears. This intermediary unit manages the transition between different gear ratios smoothly by coordinating the movement of connection units. The regulation unit acts as a mediator between the driver's input and the gear change, ensuring smooth transitions without requiring overly complex direct manipulation mechanisms.
Solution Approach 2:
The connection units are pre-positioned and pre-configured to facilitate smooth gear transitions. Before a gear change is initiated, the connection units are already in position to engage with the appropriate gears. This preliminary positioning allows for smoother and faster gearshifting, as the mechanical components are prepared in advance rather than requiring complex real-time adjustments during the gear change process.
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
Enables efficient and smooth gearshifting between low and high speeds, optimizing energy use and reducing the effort required for pedaling, particularly on varying terrain.
Implementation Method 1
a plurality of planetary gears tooth-engaged between the ring gear and the sun gear
Implementation Method 2
shift to a first gear via rotation of the sun gear, may shift to a second gear via rotation of the ring gear, and may shift to a third gear via rotation of both the ring gear and the sun gear
Implementation Method 3
connected to a driving pulley, which is connected to a pedal crank, via a belt
Data Source
AI summary
Provided is a bicycle with an automatic transmission, and more particularly, a bicycle with an automatic transmission for enabling rapid and smooth gearshifting from a low speed to a high speed or from a high speed to a low speed.