Electronic Rear Derailleur Encoder Layout for Precise Shifting
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Solution Overview
Problem
Existing bicycle derailleurs lack efficient and precise electronic control mechanisms for gear shifting, particularly in electromechanical rear derailleurs, which can lead to inaccurate positioning and increased wear due to mechanical limitations.
Innovation Solution
An electronic rear derailleur system featuring a base member, movable member, linkage, transmission, motor, encoder gear, and absolute encoder, where the encoder gear is independent of the load path and operates over a 360-degree range, providing high resolution and precise control through a motor-driven transmission mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a motor-driven transmission mechanism with encoder gear is used, then positioning precision and control accuracy are improved, but device complexity increases
Solution Approach 1:
The encoder gear acts as an intermediary component between the motor and the load path. It provides precise positional feedback to the control system without being part of the force transmission chain, enabling accurate positioning while maintaining mechanical simplicity in the load path.
Solution Approach 2:
The system separates the measurement function (encoder gear) from the power transmission function (load path gears). This segmentation allows the encoder gear to rotate independently and provide precise positional information without bearing mechanical loads, thereby improving measurement precision without proportionally increasing overall device complexity.
2Measurement precision
If the encoder gear is independent of the load path, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The encoder gear serves as a mediator that interfaces with the load path through meshing with the output gear but remains mechanically independent. This allows it to accurately sense rotational position without being subjected to the same mechanical stresses and deformations as the load path components, thereby improving measurement accuracy.
3Measurement precision
If the encoder gear rotates approaching 360 degrees over the operating range, then measurement resolution is improved, but the size of the encoder gear decreases
Solution Approach 1:
The system changes the rotational parameter of the encoder gear, allowing it to rotate approaching 360 degrees over the full operating range of the output gear. This parameter change enables high measurement resolution with a compact gear size, as the encoder gear can be made about 1/4 the diameter of the output gear while still achieving near-360-degree rotation through proper meshing configuration.
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 precise and reliable gear shifting with reduced mechanical wear, allowing for accurate positioning and efficient operation over a wide range of motion, enhancing the performance and durability of the derailleur system.
Implementation Method 1
A motor 54 operates a transmission 90. The transmission includes an output gear 32 and an encoder gear 63 that is independent of the load path. The encoder gear 63 is meshed with the output gear 32, wherein the output gear operates over an angular range and the encoder gear is sized to rotate an amount approaching but not exceeding 360 degrees over the operating range of the output gear.
Implementation Method 2
The electronic rear derailleur may further comprise an absolute encoder positioned to sense the position of the encoder gear.
Data Source
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AI summary
The invention relates to an electronic rear derailleur (10) for a bicycle, comprising: a base member (1) for attachment to a frame member of the bicycle; a movable member (5) having a cage assembly (8) attached thereto; a linkage (92) coupling the movable member (5) to the base member (1) and operative to permit movement of the movable member (5) relative to the base member (1); a transmission (90) operative to move the movable member (5) relative to the base member (1), the transmission (90) including a plurality of gears (57, 58, 59, 60, 61, 62, 32, 64) in a load path and an encoder gear (63) independent of the load path and receiving rotational input from one of the plurality of gears (57, 58, 59, 60, 61, 62, 32, 64) of the transmission (90); and a motor (54) to operate the transmission (90).