Active Derailleur Lock Mechanism for Chain Tension Control

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Solution Overview

Problem

Conventional derailleurs have limited control, making them incompatible with regenerative braking and back-driving, and they often experience chain slack on rough roads due to their free pivoting nature, restricting their functionality and responsiveness.

Innovation Solution

An active derailleur system with a lock mechanism that includes a pivot assembly and a controller to manage chain tension, allowing for controlled shifting and regenerative braking by locking and unlocking the derailleur to match pedal torque and shift conditions, enabling back-driving and maintaining chain tension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the derailleur is allowed to freely pivot to maintain chain tension, then chain tension is maintained, but the derailleur cannot support regenerative braking and back-driving functions

Engineering Contradiction:

Improvefunctional versatilityVSAvoidchain tension stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The derailleur pivot assembly transitions from a static free-pivoting state to a dynamic state where the pivot can be selectively locked and unlocked. The lock mechanism engages with the swing arm to prevent pivoting during regenerative braking, while allowing free pivoting during normal operation to maintain chain tension.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The derailleur system is enhanced with a lock mechanism that enables multiple functions: normal gear shifting with free pivoting, regenerative braking with locked pivot, and back-driving capability. This transforms a single-function free-pivoting derailleur into a multi-functional system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If the derailleur is locked to prevent chain slack on rough roads, then chain tension stability is improved, but the derailleur cannot perform gear shifting

Engineering Contradiction:

Improvechain tension stabilityVSAvoidgear shifting capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The lock mechanism operates periodically, switching between locked and unlocked states based on operational requirements. It is unlocked during gear shifting operations to allow chain movement, then locked during normal riding to maintain chain tension and prevent slack.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If a lock mechanism is added to enable regenerative braking and back-driving, then functional versatility is improved, but device complexity increases

Engineering Contradiction:

Improvefunctional versatilityVSAvoidderailleur structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The lock mechanism is integrated with the existing swing arm and pivot assembly of the derailleur. The lock effector combines with the swing arm to form a unified structure that provides both locking functionality and maintains the original chain tensioning capability, rather than adding a completely separate mechanism.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11377170B2Active derailleur system and method

Publication Date: 2022.07.05 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Systems and methods are provided for actively controlling a derailleur. A derailleur system includes a cassette including a number of sprockets, a drive unit that drives the cassette, and a chain linking the drive unit with the cassette. A derailleur is configured to guide the chain around the cassette, the derailleur including a swing arm rotatable at a pivot assembly to maintain tension on the chain. A lock selectively locks the swing arm from rotating.