Keyboard Pivot Shaft Reinforcement for Stress Distribution

Solution Overview

Problem

Existing pivot mechanisms in keyboard instruments, such as electronic pianos, face high stress due to the combination of key pressing and stopper actions, which demands strong and stiff shafts to maintain durability but often results in inadequate strength and stiffness, leading to potential mechanical failures.

Innovation Solution

The implementation of a pivot mechanism with a shaft portion and a bearing, where the shaft has reinforcements protruding from its outer surface, specifically in regions not directly contacted by the bearing during pivotal movement, to distribute and absorb stress more effectively, enhancing the shaft's strength and stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shaft portion is made stronger and stiffer to withstand heavy stress from key pressing and stopper actions, then the durability of the pivot mechanism is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvedurability of pivot mechanismVSAvoidstructural complexity of shaft

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shaft portion features a reinforcement protrusion that creates non-uniform thickness distribution - thinner in regions where bearing contact occurs and thicker in regions opposite the bearing contact. This local quality variation allows the shaft to have adequate strength and stiffness where needed while maintaining simplicity in other areas, resolving the contradiction between durability and structural complexity.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the shaft portion is designed with uniform thickness for simplicity, then the ease of manufacture is improved, but the strength and stiffness are insufficient to handle the heavy stress from dual actions

Engineering Contradiction:

Improvemanufacturing simplicity of shaftVSAvoidstrength and stiffness of shaft

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The shaft portion features a reinforcement protrusion that creates non-uniform thickness distribution - thinner in regions where bearing contact occurs and thicker in regions opposite the bearing contact. This local quality variation allows the shaft to have adequate strength and stiffness where needed while maintaining simplicity in other areas, resolving the contradiction between durability and structural complexity.

Inventive Principle:

Principle #3Local quality

3Reliability

If the shaft portion has increased strength and stiffness through reinforcement, then the durability is improved, but the stress concentration in certain regions may increase

Engineering Contradiction:

Improvedurability of pivot mechanismVSAvoidstress concentration on shaft

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The shaft portion features a reinforcement protrusion that creates non-uniform thickness distribution - thinner in regions where bearing contact occurs and thicker in regions opposite the bearing contact. This local quality variation allows the shaft to have adequate strength and stiffness where needed while maintaining simplicity in other areas, resolving the contradiction between durability and structural complexity.

Inventive Principle:

Principle #3Local quality

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 configuration improves the durability of the pivot mechanism by distributing stress more evenly and reducing concentration on the shaft, thereby enhancing its strength and stiffness, leading to a more reliable and long-lasting mechanical action.

Implementation Method 1

a bearing configured to contact the shaft portion and pivot about a pivot axis

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS10825435B2Pivot mechanism and keyboard apparatus including the same

Publication Date: 2020.11.03 YAMAHA CORP

AI summary

A pivot mechanism includes: a shaft portion; a bearing configured to contact the shaft portion and pivot about a pivot axis; and a reinforcement protruding from an outer circumferential surface of the shaft portion. The outer circumferential surface includes a first region contactable by the bearing in a range of its pivotal movement and a second region not including the first region in a region opposed to the first region via the pivot axis. The reinforcement extends from at least a portion of the second region to an outside of the bearing in a pivot-axis direction.