Lightweight Balance Wheel Screws for Precise Inertia Adjustment

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Solution Overview

Problem

Conventional balance wheels with adjustable inertia adjustment elements, such as screws or weights, require significant time and expertise to adjust due to large mass changes causing substantial rate deviations, which are difficult to correct.

Innovation Solution

The balance wheel incorporates inertia adjustment elements made of lightweight materials with reduced volume mass, such as titanium alloys or ceramics, allowing for precise adjustments with minimal rate errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If heavy screws or weights are used as inertia adjustment elements, then the adjustment range of the balance wheel's moment of inertia is increased, but handling errors cause significant rate deviations that are difficult to correct

Engineering Contradiction:

Improveadjustment range of moment of inertiaVSAvoidrate deviation accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter (density) of the inertia adjustment elements from heavy materials to lightweight materials. This parameter change reduces the mass of the adjustment elements, thereby reducing the rate deviation caused by handling errors while maintaining the adjustment range through proper design of the adjustment mechanism geometry

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite construction by combining the balance wheel rim made of one material with inertia adjustment elements made of a different lightweight material. This allows optimization of each component's material properties - the rim for structural integrity and the adjustment elements for minimal rate deviation during adjustment

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If multiple regulating screws are used to adjust the balance wheel, then the moment of inertia can be adjusted, but the adjustment process becomes time-consuming and difficult

Engineering Contradiction:

Improveadjustability of oscillation frequencyVSAvoidadjustment time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

By changing the material parameter to lightweight materials, the patent reduces the mass effect of each screw, which reduces the time needed for fine adjustments. The lighter screws require smaller correction movements, speeding up the adjustment process while maintaining the full range of adjustability

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If heavy inertia adjustment elements are used, then significant changes in moment of inertia can be achieved, but small handling errors lead to large rate deviations

Engineering Contradiction:

Improvemass of inertia adjustment elementsVSAvoidrate setting accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent applies parameter change by selecting materials with lower density for the inertia adjustment elements. This reduces the mass of these elements, which directly reduces the magnitude of rate deviations caused by small handling errors during adjustment, while the adjustment mechanism is designed to provide sufficient adjustment range

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4685578A1Balance wheel with light inertia adjustment elements for watch movements

Publication Date: 2026.01.28 RICHEMONT INTERNATIONAL SA

Figure 1

AI summary

The present invention relates to a balance wheel for integration into a regulating organ of a clockwork mechanism, comprising a rim (1), spokes (2a, 2b) and a pivot axis (4), wherein the rim (1) is connected to the pivot axis (4) of the balance wheel via the spokes (2a, 2b) and is made of at least one first material, and wherein the balance wheel has a plurality of adjustable inertia adjustment elements (6). The balance wheel is characterized in that the entirety of the inertia adjustment elements (6) is made of a second material, wherein the volume mass of the second material is less than 6 g/cm³.