Stepless Bicycle Transmission via Curved Guide Slots
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Solution Overview
Problem
Conventional bicycle derailleur mechanisms are limited by the number of available sprockets, restricting stepless control of bicycle speed.
Innovation Solution
A transmission device comprising a first, second, and third plate with angularly spaced guide slots and guide pins that allow for smooth sliding movement, enabling stepless speed control by adjusting the position of the guide pins within the guide slots during rotation, thereby varying the rotational speed of the transmission unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional derailleur mechanism with fixed number of sprockets is used, then structure is simple, but speed control is limited and cannot achieve stepless adjustment
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed sprocket system into a dynamic, continuously adjustable transmission mechanism. The guide pins move along curved guide slots on rotating plates, enabling the transmission ratio to vary continuously rather than in discrete steps. This dynamic adjustment mechanism allows stepless speed control while maintaining a relatively simple structural composition consisting of plates, guide slots, and guide pins.
2Adaptability or versatility
If more sprockets are added to expand speed control range, then speed adjustment capability improves, but device complexity and number of parts increase
Solution Approach 1:
The patent applies segmentation by dividing the continuous adjustment range into multiple adjustable positions through the interaction of guide pins with guide slots on different plates. Instead of using multiple discrete sprockets, the system segments the adjustment capability across three plates with differently oriented guide slots, allowing the guide pins to achieve various transmission ratios through their positions along the curved paths.
Solution Approach 2:
The patent applies universality by designing the guide pins to serve multiple functions simultaneously - they guide the relative motion between plates, define the transmission ratio through their position in guide slots, and enable continuous adjustment across the entire speed range. This multi-functional design eliminates the need for separate components for each speed ratio that would be required in a conventional multi-sprocket system.
3Ease of operation
If fixed sprocket positions are used, then manufacturing is simple, but operational flexibility and continuous speed adjustment are limited
Solution Approach 1:
The patent applies preliminary action by pre-configuring the guide slots on the plates with specific curved geometries that determine the transmission ratio characteristics. The guide slots are manufactured with precise curved paths that guide the guide pins through the desired motion trajectories, enabling continuous speed adjustment without requiring complex real-time control mechanisms during operation.
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 stepless control of bicycle speed through smooth sliding movement of guide pins, allowing for continuous adjustment of rotational speed without the limitations of fixed sprocket numbers, enhancing user control and efficiency.
Implementation Method 1
The guide pins are respectively and slidably disposed in the second guide slots. Each of the guide pins has a first end portion that slidably extends into a respective one of the first guide slots, and a second end portion that slidably extends into a respective one of the third guide slots
Data Source
AI summary
A transmission device includes a plurality of guide pins, a first plate having multiple first guide slots, a second plate having multiple second guide slots, and a third plate having multiple third guide slots. A projection of each of the first guide slots on the third plate is deviated from a respective one of the third guide slots in a first rotational direction. A projection of each of the second guide slots is deviated from a respective one of the third guide slots in a second rotational direction which is opposite to the first rotational direction. The guide pins are respectively and slidably disposed in the second guide slots. When the first plate rotates, the guide pins slide synchronously and are equidistant from an axis.