Gear Assembly Hardness Washer Friction Reduction

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Solution Overview

Problem

In mechanical timepieces, high friction between the shaft and the support member in the wheel train mechanism increases energy consumption and can lead to wear, reducing the lifespan of the product.

Innovation Solution

A gear assembly comprising a shaft with a gearwheel, a tube into which the shaft is inserted, and a washer interposed between the shaft and the tube, where the washer has a higher hardness than the tube, reducing friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the shaft is supported by the tube in surface contact, then the structure is simple, but friction increases and wear occurs

Engineering Contradiction:

Improvestructure simplicityVSAvoidfriction

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

A washer is introduced as an intermediary component between the shaft and the tube. The washer has a higher hardness than the tube and reduces friction through its material properties. This intermediary element resolves the contradiction by maintaining structural simplicity while significantly reducing friction and wear between the shaft and tube contact surfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the shaft is supported by the tube in surface contact, then the assembly is compact, but wear increases reducing lifespan

Engineering Contradiction:

Improveassembly compactnessVSAvoidproduct lifespan

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The washer serves as a protective intermediary between the shaft and tube, preventing direct wear contact. By positioning the washer at the contact interface, it absorbs wear and reduces friction, thereby extending the lifespan of both the shaft and tube while maintaining the compact assembly structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the hardness parameter of the intermediary component. The washer is specifically designed with a higher hardness than the tube, which alters the friction and wear characteristics of the contact interface. This parameter change enables reduced wear and extended product lifespan without compromising assembly compactness.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If a softer material is used for the tube, then manufacturing is easier, but friction increases

Engineering Contradiction:

Improvemanufacturing easeVSAvoidfriction

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The washer acts as an intermediary that compensates for the softer tube material. While the tube remains easy to manufacture with softer material, the harder washer inserted between the shaft and tube reduces friction. This resolves the contradiction by decoupling the manufacturing ease of the tube from the friction performance of the assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250103004A1Gear assembly and timepiece

Publication Date: 2025.03.27 CASIO COMPUTER CO LTD

AI summary

Disclosed is a gear assembly, including: a shaft with a gearwheel; a tube into which the shaft is inserted; and a washer interposed between the shaft and the tube in an axial direction of the shaft, wherein the washer has a higher hardness than the tube.