Upright Piano Jack Motion-Restricting Device
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Solution Overview
Problem
In upright pianos, the jack motion-restricting components, such as the butt felt and regulating button, face issues due to humidity changes and abrasion, leading to inconsistent key touch and let-off timing, as well as noise generation.
Innovation Solution
A jack motion-restricting device with a base part made of chemically stable material and a surface layer with abrasion resistance and flexibility, where the jack abuts against the surface layer, maintaining a constant motion-restricting position and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the butt felt is made of woolen felt to absorb shock and prevent noise, then noise generation is reduced, but the felt expands or shrinks according to humidity changes causing displacement of the jack stationary position
Solution Approach 1:
The invention uses a composite structure consisting of a base layer made of chemical fiber (providing dimensional stability) and a surface layer made of fluoropolymer fiber (providing shock absorption and noise reduction). This composite material approach allows each layer to contribute its specific property, resolving the contradiction between noise reduction and dimensional stability.
Solution Approach 2:
The invention applies different material properties to different layers of the butt felt. The base layer uses chemical fiber for dimensional stability, while the surface layer uses fluoropolymer fiber for shock absorption and noise reduction. This local differentiation of material qualities allows each region to perform its specific function optimally.
2Object-affected harmful factors
If the regulating button is made of leather to prevent noise, then noise generation is reduced, but the jack slides on the surface causing abrasion and change in thickness
Solution Approach 1:
The regulating button uses a composite structure with a base layer of chemical fiber for dimensional stability and a surface layer of fluoropolymer fiber for abrasion resistance and noise reduction. This resolves the contradiction by combining materials that provide both noise reduction and wear resistance.
Solution Approach 2:
The invention changes the material parameters of the regulating button by using fluoropolymer fiber instead of traditional leather or felt. This material parameter change provides both noise reduction and superior abrasion resistance, preventing the jack from sliding and causing wear.
3Stability of the object's composition
If the butt felt is made of harder material like leather to prevent expansion and shrinkage, then dimensional stability is improved, but noise is liable to occur due to jack abutment
Solution Approach 1:
The invention uses a composite structure where the base layer of chemical fiber provides dimensional stability, while the surface layer of fluoropolymer fiber provides shock absorption and noise reduction. This resolves the contradiction by having each layer fulfill its specific function.
Solution Approach 2:
The invention applies different material properties to different layers: the base layer uses chemical fiber for dimensional stability, while the surface layer uses fluoropolymer fiber for noise reduction and shock absorption. This local differentiation allows the harder base material to maintain stability while the softer surface layer reduces noise.
4Object-affected harmful factors
If the same felt is used for the regulating button to prevent noise, then noise generation is reduced, but the felt expands or shrinks with humidity changes causing displacement of the jack abutment position
Solution Approach 1:
The regulating button uses a composite structure with a chemical fiber base layer for dimensional stability and a fluoropolymer fiber surface layer for noise reduction. This resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The invention differentiates the material properties within the regulating button: the base layer uses chemical fiber for dimensional stability, while the surface layer uses fluoropolymer fiber for noise reduction. This local quality differentiation prevents both noise and dimensional instability.
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
The device ensures stable jack operation by maintaining constant thickness and position, reducing noise and abrasion, and providing consistent key touch and let-off timing, while using fluoropolymer fibers for the surface layer to enhance lubricity and reduce manufacturing costs.
Implementation Method 1
using fluoropolymer fibers for the surface layer to enhance lubricity and reduce manufacturing costs
Data Source
AI summary
A jack motion-restricting device for an upright piano, which is capable of maintaining constant a jack motion-restricting position by a simple construction to thereby obtain an intended operation of the jack. The jack motion-restricting device restricts the motion of the jack operating in accordance with key depression by having the jack abut thereagainst. A base part of the device is provided at a location close to the jack. A base layer of the same is formed of a material having dimensional stability, and is affixed to the base part. A surface layer of the same is formed of a material having abrasion resistance and flexibility, and is affixed to the base layer, for having the jack abut thereagainst.