Bicycle Crank Arm Sensor Support Member Strain Transmission

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Solution Overview

Problem

Existing bicycle crank arm force sensors, such as those using strain gauges, require accurate installation and increase manufacturing costs and time, making them inefficient for detecting pedaling force effectively.

Innovation Solution

A bicycle crank arm design featuring a crank body with a sensor support member and a power sensing device mounted within a cavity, allowing for simple and accurate detection of pedaling force through a sensor support member that transmits strain to the power sensing device, which can be easily integrated into the crank arm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a strain gauge is installed on a crank arm to detect pedaling force, then measurement precision is improved, but manufacturing cost and manufacturing time increase

Engineering Contradiction:

Improvepedaling force detection accuracyVSAvoidmanufacturing cost and time

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

A sensor support member is introduced as an intermediary component between the crank arm and the power sensing device. This support member is disposed within a cavity of the crank arm and provides a mounting structure for the sensor, isolating it from direct installation on the crank arm itself. This intermediary structure simplifies the installation process and reduces manufacturing complexity while maintaining measurement accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sensor support member and power sensing device are nested within a cavity formed in the crank arm. This nested arrangement allows the sensing components to be housed inside the existing crank arm structure without requiring external modifications or additional mounting space, thereby simplifying manufacturing while preserving measurement precision.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Ease of manufacture

If a power sensing device is mounted on a crank arm using a sensor support member within a cavity, then ease of manufacture is improved, but device complexity increases

Engineering Contradiction:

Improveinstallation simplicityVSAvoidcrank arm structure complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The sensor support member is integrated with the crank arm structure by disposing it within a cavity formed in the crank arm. This merging of the support member into the existing crank arm design adds minimal structural complexity while providing a simplified installation path for the power sensing device, improving ease of manufacture without significantly increasing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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

This design simplifies the installation of power sensing devices on bicycle crank arms, enhancing the accuracy and efficiency of pedaling force detection while reducing manufacturing complexities and costs.

Implementation Method 1

a sensor support member that transmits strain to the power sensing device

Methodology Applied

Scientific EffectStrain: Deformation

Data Source

PatentUS8881608B2Bicycle crank arm

Publication Date: 2014.11.11 SHIMANO INC

AI summary

A bicycle crank arm comprises a crank body, a sensor support member and a power sensing device. The crank body includes a crank axle mounting portion and a pedal mounting portion. The sensor support member is disposed in a cavity of the crank body and attached to the crank body. The power sensing device is supported on the sensor support member.