Bicycle Chain Guide with Abutment-Connected Thin Plates

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Solution Overview

Problem

Existing bicycle front derailleurs face issues with chain guides that are prone to bending under strong forces, leading to weight and manufacturing complexity, while prior solutions attempt to address this with thicker plates, resulting in increased weight and higher production costs.

Innovation Solution

A bicycle chain guide design featuring a first and second guide plate with connection parts that limit relative movement at the rear end, including an attachment flange and abutments to prevent rotational movement, constructed from thin plates for strength and lightness, and a simple, cost-effective manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the chain guide is constructed of thicker plates to prevent bending, then the strength is improved, but the weight increases

Engineering Contradiction:
ImprovestrengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The chain guide is divided into multiple thin guide plates (first guide plate, second guide plate, third guide plate) connected by connection parts. This segmentation allows each plate to remain thin and lightweight while the interconnected structure provides overall strength to resist bending forces during chain jams and normal operation.

Inventive Principle:
Principle #1Segmentation

2Weight of moving object

If the chain guide is constructed of thinner plates, then the weight is reduced, but the strength deteriorates

Engineering Contradiction:
ImproveweightVSAvoidstrength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

Multiple thin guide plates are merged into a unified structure through connection parts (first connection part, second connection part). The combined structure distributes mechanical loads across all plates and connection points, providing collective strength that prevents bending while maintaining the lightweight advantage of thin individual plates.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If the guide plates are allowed to rotate relative to each other, then the ease of operation is improved, but the reliability deteriorates

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The connection between guide plates provides rotational freedom at specific locations (connection parts) while maintaining rigid constraints at other locations (abutments). This local differentiation allows the structure to be flexible where needed for operation while remaining reliable and stable where structural integrity is required.

Inventive Principle:
Principle #3Local quality

4Reliability

If the prior art solution with abutments is used, then the reliability is improved, but the device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The abutment features are merged into the guide plates and connection parts themselves rather than being separate components. The first abutment on the first guide plate and second abutment on the first connection part are integrated into the existing structure, providing rotational constraint functionality without adding separate complex mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP1950133B1Bicycle chain guide
Publication Date: 2013.10.09 SHIMANO INC
  • EP1950133B1 patent drawingFigure 1~2
  • EP1950133B1 patent drawingFigure 3~4
  • EP1950133B1 patent drawingFigure 5~6

AI summary

A bicycle chain guide (28) includes a first guide plate (70), a second guide plate (80), a first connection part and a second connection part. The first guide plate has a first chain engagement surface and the second guide plate has a second chain engagement to form a chain receiving area (RA). The first and second connection parts extend between the first and second guide plates to connect the first and second guide plates together at first and second spaced locations, respectively. The first connection part is fixed to the first guide plate by a fastener (94). The first guide plate has a first abutment and the first connection part has a second abutment. The first and second abutments are arranged at a rear end of the chain guide to limit relative movement of the first and second guide plates.