Electric Bicycle Derailleur Motor Brake Mechanism

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Solution Overview

Problem

Existing bicycle derailleur systems are prone to involuntary displacement and misalignment due to external stresses, which can cause friction and gear shifting issues, and current solutions either oversize the motor gear or employ complex and inefficient anti-reverse clutches.

Innovation Solution

A derailleur system with an electrically controllable device featuring a gear train and toothed members that selectively engage and disengage to stabilize the motor shaft during gear shifting, consuming power only when necessary, thereby reducing energy usage and minimizing displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the motor gear is oversized to withstand external stresses, then reliability is improved, but weight and cost increase

Engineering Contradiction:

Improvemotor gear stabilityVSAvoidmotor gear weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent applies a dynamic approach by using a brake mechanism that is activated only during gear shifting operations. The brake is not continuously engaged but rather applied dynamically when needed to prevent involuntary displacement during the vulnerable gear change phase, allowing the motor gear to be smaller while maintaining reliability during critical operations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The brake mechanism operates periodically during gear shifting events rather than continuously. The control system detects when a gear shift is initiated and activates the brake temporarily during this period, then releases it during normal operation, reducing the overall stress requirements on the motor gear sizing.

Inventive Principle:

Principle #19Periodic action

2Reliability

If continuous power is supplied to prevent displacement, then reliability is improved, but energy consumption increases

Engineering Contradiction:

Improveposition stabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system uses the existing gear shift detection capabilities and control infrastructure to trigger the brake mechanism automatically. The brake is integrated into the existing control flow, utilizing the same sensors and control logic that manage gear shifting, rather than requiring a separate continuous control system.

Inventive Principle:

Principle #25Self-service

3Reliability

If complex anti-reverse clutches are used to prevent involuntary displacement, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvedisplacement preventionVSAvoidclutch mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the displacement prevention function from the motor gear itself and implements it as a separate brake mechanism. Rather than making the motor gear complex to handle reverse forces, the solution separates the functions: the motor gear handles torque transmission while the brake handles displacement prevention during gear shifts.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The brake mechanism acts as an intermediary between the motor gear and the external stresses. During gear shifting, the brake temporarily mediates the force transmission, preventing involuntary displacement without requiring the motor gear itself to be designed for complex force management.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Weight of moving object

If the motor gear is made smaller to reduce weight, then weight is reduced, but vulnerability to external stresses increases

Engineering Contradiction:

Improvemotor gear weightVSAvoidstress resistance

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The brake mechanism provides beforehand protection by being activated before involuntary displacement can occur. The control system detects the gear shift initiation and pre-applies the brake to cushion against external stresses that would otherwise cause displacement of the smaller, more vulnerable motor gear.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP3251941B1Electric bicycle derailleur

Publication Date: 2020.08.19 CAMPAGNOLO SRL

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AI summary

A bicycle derailleur comprising a chain guide and an electric motor (12) that displaces the chain guide further comprises an electrically controllable device (50) configured to, selectively, block the rotation of the electric motor (12) and let the electric motor (12) free to rotate. A method for actuating a bicycle derailleur comprising a chain guide and an electric motor (12) that displaces the chain guide, comprises the steps of: - receiving a gearshifting request signal, - making the electric motor (12) free to rotate, - driving the electric motor (12) to displace the chain guide until the chain guide is in an intended position while the electric motor (12) is made free to rotate, and - blocking the rotation of the electric motor (12).