Escapement Wheel Tooth Profile for Low-Friction Torque Transfer

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Solution Overview

Problem

Existing escapement systems in watches suffer from suboptimal energy transmission and increased friction due to the planar contact surfaces between the escape wheel and the locking mechanism, leading to inefficiencies in energy utilization.

Innovation Solution

The escapement system features an escape wheel with optimized transmission surfaces, including convex and concave profiles on the teeth, allowing for point or linear contact with the locking mechanism to minimize friction and enhance energy transfer efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional escapement mechanism is used in a clock, then the clock can maintain accurate timekeeping, but the escapement components are subject to wear and degradation over time which eventually requires replacement

Engineering Contradiction:
Improvetimekeeping accuracyVSAvoidescapement lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent replaces the traditional mechanical escapement components (escape wheel, pallet fork, anchor) with a magnetic field-based escapement system. Magnets are positioned on the escape wheel and interact with a magnetic field generated by an electromagnet or permanent magnet, eliminating direct mechanical contact between escapement parts. This substitution of mechanical interaction with magnetic interaction resolves the contradiction by maintaining the timing function while eliminating wear, thereby extending the escapement's operational lifespan indefinitely while preserving timekeeping accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If traditional mechanical escapement components are used, then the clock mechanism is relatively simple in design, but the mechanical parts experience friction and wear that degrades performance over time

Engineering Contradiction:
Improveescapement structureVSAvoidcomponent durability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent substitutes mechanical contact-based escapement interaction with magnetic field-based interaction. Instead of relying on physical contact between escape wheel teeth and pallet fork surfaces, the system uses magnets attached to the escape wheel that interact with a magnetic field. This reduces device complexity by eliminating the need for precisely machined contact surfaces and reduces friction, thereby improving component durability and reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If conventional escapement mechanisms are employed, then the clock can function with standard mechanical parts, but the friction between moving parts generates heat and accelerates material degradation

Engineering Contradiction:
Improvemanufacturing standardizationVSAvoidfriction and heat
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical friction-based interaction with magnetic field interaction. Magnets are positioned on the escape wheel and interact with a magnetic field without physical contact, eliminating friction and heat generation. This substitution maintains ease of manufacture through standardized magnetic components while eliminating the harmful effects of friction and thermal degradation that affect conventional mechanical escapements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Duration of action of stationary object

If a magnetic field-based escapement is implemented, then wear and friction are minimized extending component life, but the mechanism becomes more complex with magnetic components and field control systems

Engineering Contradiction:
Improveescapement lifespanVSAvoidmagnetic system structure
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent implements a magnetic field-based escapement where magnets are attached to the escape wheel and interact with a magnetic field generated by an electromagnet or permanent magnet. This substitution extends escapement lifespan by eliminating mechanical wear and friction. The complexity increase is managed by using straightforward magnetic components and field control mechanisms that, while different from traditional mechanical parts, provide a reliable and maintainable system with significantly extended operational life.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 optimized escapement system reduces energy loss by minimizing sliding contact and maintaining consistent torque transmission, thereby improving the efficiency of the watch's mechanical operation.

Implementation Method 1

an oscillating object in a clock mechanism generates an electrical signal in a coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3844572B1Timepiece escapement
Publication Date: 2026.05.20 ROLEX SA
  • EP3844572B1 patent drawingFigure 1
  • EP3844572B1 patent drawingFigure 2
  • EP3844572B1 patent drawingFigure 3

AI summary

The invention relates to an escapement wheel (1; 1') comprising at least one escapement tooth (10; 10'), at least one of the escapement teeth having a transmission surface (11; 11') comprising a first proximal contact surface (11a; 11a') and a second distal contact surface (11b; 11b') which are intended to come into contact with the escapement lock (2), the first proximal contact surface (11a; 11a') being exclusively dedicated to the mechanical transmission of torque from the escapement wheel towards the lock and being arranged so as to act by means of linear contact with the lock during the mechanical transmission of torque from the escapement wheel towards the lock.