Escapement Wheel Bore Structure for Lower Inertia

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Solution Overview

Problem

Existing escape wheels in watchmaking exhibit high inertia, which leads to inefficiencies and are difficult and costly to manufacture, particularly when made of low-density materials like silicon or through skeletonization.

Innovation Solution

A wheel design with bores on both faces extending from the rim to the hub, featuring grooves with specific dimensions and configurations, made of materials like steel or metal alloys, to reduce inertia while maintaining structural integrity and ease of manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If skeletonization or low-density material (silicon) is used to reduce inertia, then inertia is reduced, but manufacturing complexity and time increase, and fragility increases

Engineering Contradiction:
ImproveinertiaVSAvoidmanufacturing complexity
Core Design Contradiction:
Weight of moving objectVSEase of manufacture

Solution Approach 1:

The wheel is divided into multiple segments by creating bores through the radial arms, separating the solid structure into distinct sections while maintaining overall structural integrity. This segmentation reduces mass and inertia without requiring complete skeletonization

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wheel incorporates a porous or hollow structure through the bores created in the radial arms, reducing material density and overall mass while maintaining structural strength through the remaining material framework

Inventive Principle:
Principle #31Porous materials

2Weight of moving object

If skeletonization is used to reduce inertia, then inertia is reduced, but manufacturing time increases

Engineering Contradiction:
ImproveinertiaVSAvoidmanufacturing time
Core Design Contradiction:
Weight of moving objectVSProductivity

Solution Approach 1:

The bores are created as preliminary features during the manufacturing process, allowing subsequent assembly and finishing operations to proceed more quickly. The structural framework is prepared in advance with the correct mass distribution built-in

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention optimizes parameters such as bore diameter, bore depth, and arm thickness to achieve the desired inertia reduction while maintaining manufacturability within standard production timeframes

Inventive Principle:
Principle #35Parameter changes

3Weight of moving object

If skeletonization or silicon material is used to reduce inertia, then inertia is reduced, but structural strength and durability decrease

Engineering Contradiction:
ImproveinertiaVSAvoidstructural integrity
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

Different regions of the wheel have different structural properties - the radial arms contain bores for mass reduction while the rim and hub maintain solid construction for strength. The teeth and engagement surfaces are reinforced to handle mechanical loads

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The wheel combines different material properties within a single component - using solid material where strength is critical (hub, rim, teeth) and hollow or porous material where mass reduction is prioritized (radial arms), creating a composite structure optimized for both strength and low inertia

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4290314B1Wheel for an escapement system with reduced inertia
Publication Date: 2025.12.17 NIVAROX FAR SA
  • EP4290314B1 patent drawingFigure 1~3

AI summary

The invention relates to a wheel for an escapement system (1) comprising a hub (2) intended to be fixed for rotation with an axle, the axle being intended to be subjected to a mechanical torque, a rim (3), at least two arms (4) extending from the hub (2) to the rim (3), and teeth formed by a plurality of teeth (5). According to the invention, the wheel for the escapement system (1) comprises at least one bore (10) on at least one of its faces, the bore (10) extending from the rim (3) to the hub (2).