Detent Escapement Shock Resistance and Release Energy

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Solution Overview

Problem

The detent escapement mechanism in clock movements experiences significant energy loss and lacks sufficient shock resistance, particularly in wristwatches, due to the high energy required to release the escape wheel and the risk of disturbance from shocks, which affects the balance-spring system and chronometric performance.

Innovation Solution

A direct impulse escapement with a detent rocker featuring a stop element and a sliding surface that alternately enters the path of the escape wheel toothing, providing additional security and preventing premature return, along with a safety surface outside the tooth path to enhance shock resistance, and an inertial member that ensures energy-efficient release without overcoming any obstacle during oscillation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second flexible element is made sufficiently rigid to maintain locking, then the escape wheel can be kept locked securely, but the energy required to release the escape wheel increases significantly

Engineering Contradiction:
Improvelocking securityVSAvoidrelease energy
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs a dynamic release mechanism where the detent rocker pivots about a fulcrum during the release process. The release finger interacts with the release element in a controlled pivoting motion, allowing the system to transition from a locked to unlocked state with minimal energy input. This dynamic pivoting action converts a small input force into the necessary release torque without requiring excessive energy storage in rigid flexible elements.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If the detent mechanism is designed for precise chronometric performance, then adjustment precision is improved, but the system becomes more delicate and vulnerable to shocks

Engineering Contradiction:
Improvechronometric precisionVSAvoidshock sensitivity
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates a safety surface on the detent rocker that extends beyond the tooth path. This safety surface acts as a protective feature that prevents the stop element from prematurely entering the tooth path during shock events. The safety surface is positioned to engage with the escape wheel tooth before the stop element could be displaced into the critical locking position, thereby cushioning against shock-induced disturbances while maintaining precise chronometric adjustment capabilities.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the stop element is positioned to provide maximum locking reliability, then the escape wheel is securely held, but the risk of premature return to the tooth path increases during shocks

Engineering Contradiction:
Improvelocking reliabilityVSAvoidshock disturbance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a safety surface as an intermediary protective feature between the stop element and the escape wheel tooth path. This safety surface acts as a mediator that prevents direct interaction between the stop element and the tooth path during shock events. The safety surface is positioned to engage with the escape wheel tooth before the stop element could be displaced into the critical locking position, thereby preventing shock-induced disturbances while maintaining locking reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Object-affected harmful factors

If the release mechanism is made more robust to resist shocks, then shock resistance is improved, but the energy loss during release increases

Engineering Contradiction:
Improveshock resistanceVSAvoidrelease energy loss
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent employs a dynamic release mechanism where the detent rocker pivots about a fulcrum during the release process. The release finger interacts with the release element in a controlled pivoting motion, allowing the system to transition from a locked to unlocked state with minimal energy input. This dynamic pivoting action converts a small input force into the necessary release torque without requiring excessive energy storage in rigid flexible elements, thereby reducing energy loss while maintaining shock resistance.

Inventive Principle:
Principle #15Dynamics

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 solution enhances safety against shocks and reduces energy loss during the release process, maintaining precise oscillation and improving the overall chronometric performance by minimizing unnecessary energy expenditure and maintaining the balance-spring system's stability.

Implementation Method 1

this sliding surface being shaped so that the force exerted on it by a tooth of the escape wheel causes the stopper of the trigger lever to return to the trajectory of the escape wheel toothing

Methodology Applied
Scientific EffectForce: Force

Implementation Method 2

the system must overcome the pull of the escape wheel and the second flexible element, which causes a considerable loss of energy because the energy supplied to the second flexible element to deform it

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2224292B1Detent escapement for timepiece movement
Publication Date: 2012.10.10 ROLEX SA
  • EP2224292B1 patent drawingFigure 1~4
  • EP2224292B1 patent drawingFigure 5~8
  • EP2224292B1 patent drawingFigure 9~11

AI summary

The escapement has arresting element inserted into the path of the teeth of the escape wheel comprising a sliding surface integral with the detent rocker, so as to move into the path of the teeth. The arresting element of the detent rocker comprises a safety surface (4e) situated outside the path of the teeth and adjacent to the path, when the detent rocker is in the unlocking position. The movement of the arresting element into the path of the teeth is prevented, when the escape wheel communicates the movement impulse to the balance wheel.