Segmented Chain Guard for Electric Bicycle Motor Housing

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Solution Overview

Problem

Existing chain guards for electric bicycles with electric motors require the removal of additional components like the crank and sprocket for installation and removal, making them cumbersome and time-consuming.

Innovation Solution

A chain guard design featuring two lateral sections extending parallel to each other, with a gap to accommodate the chain, that can be easily mounted and dismounted without removing other parts, using screws to secure it to the motor housing and allowing for visual inspection and easy cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional chain guard designs are used, then the chain and sprocket are protected from soiling and clothing contact, but the chain guard requires removal of additional parts like crank and sprocket for installation and removal

Engineering Contradiction:
Improveprotection from soiling and clothing contactVSAvoidease of mounting and dismounting
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The chain guard is divided into a first part in the form of a ring surrounding the sprocket and a second part fixed to the first part that extends along the chain. This segmentation allows the chain guard to be installed independently without removing the crank or sprocket, as each part can be positioned and secured separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first annular part of the chain guard is designed to fit over the sprocket in a nested configuration, while the second part extends outward to cover the chain. This nesting allows the chain guard to be installed over existing components without requiring their removal, maintaining protection functionality while improving ease of operation.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Object-affected harmful factors

If the chain guard is designed to cover the entire sprocket ring section, then protection against soiling and clothing contact is enhanced, but the device complexity increases

Engineering Contradiction:
Improveprotection coverageVSAvoidstructure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The chain guard is segmented into two functional parts: an annular ring portion for covering the sprocket and a linear extension portion for covering the chain. This segmentation achieves comprehensive protection while keeping each component relatively simple in structure, avoiding the need for a single complex enclosing structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the chain guard have different structural characteristics optimized for their specific functions. The annular part is designed to fit the sprocket geometry, while the extension part is designed to follow the chain path. This local optimization provides effective protection without uniformly increasing overall device complexity.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3348467B1Chain guard for an electric bicycle
Publication Date: 2021.07.21 MIRANDA & IRMAO LDA
  • EP3348467B1 patent drawingFigure 1
  • EP3348467B1 patent drawingFigure 2
  • EP3348467B1 patent drawingFigure 3

AI summary

This application refers to a chain guard (10) for an electric bicycle having an electric motor with a motor housing (12). The chain guard (10) comprises means for mounting it to the motor housing (12) so that the chain guard (10) covers a section of a chain located on a sprocket (16) driven by the electric motor. It is an object to provide a chain guard that can be easily mounted and dismounted. For this purpose, the chain guard (10) comprises two lateral sections (22, 24) extending at a distance from and parallel to one another at least over a ring section (26) that corresponds to a portion of the sprocket (16) engaging the chain. Also the chain guard (10) comprises at least one peripheral section (28a, 28b, 28c) extending between the two lateral sections (22, 24) and defining a gap (30) between the two lateral sections (22, 24) for accommodating the chain.