Lever Escapement Self-Alignment via Contact Angle Optimization

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Solution Overview

Problem

Conventional lever escapements for timepieces require delicate and time-consuming adjustments to account for manufacturing tolerances to ensure precise positioning of the anchor, which affects the performance of the escapement.

Innovation Solution

The design of the escapement features an escapement wheel, balance wheel, anchor with entry and exit pallets, and a reference axis, where the angles of contact and rest are optimized such that the anchor naturally aligns to a balanced position without external pins, utilizing driving planes to create a torque that stabilizes the anchor, eliminating the need for adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional lever escapements use fixed pins to limit anchor amplitude, then the anchor rest positions are defined, but delicate and time-consuming adjustments are required to account for manufacturing tolerances

Engineering Contradiction:
Improveescapement performance consistencyVSAvoidadjustment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The escapement wheel tooth profiles are designed with specific geometric parameters (angles α and β) that enable the anchor to automatically find its optimal rest position through the interaction of the tooth flanks with the pallet rest planes. This self-adjusting mechanism eliminates the need for manual adjustment operations while ensuring consistent escapement performance across manufacturing tolerances.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the geometric parameters of the escapement wheel teeth (specifically the angles α and β defined in the patent) to create a configuration where the anchor naturally settles into the correct rest position. By optimizing these angular parameters, the system achieves tolerance compensation without requiring post-manufacturing adjustments.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If manual adjustment of pallet positions is performed to achieve correct operation, then precise positioning is obtained, but the process becomes long and delicate

Engineering Contradiction:
Improvepallet positioning precisionVSAvoidescapement assembly rate
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The escapement mechanism is designed so that the anchor automatically positions itself correctly through the geometric interaction between the escapement wheel teeth and pallet rest planes. The specific angle relationships (α and β) ensure that manufacturing variations are compensated, allowing assembly without precision adjustment operations.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The correct geometric parameters for the escapement wheel teeth are predetermined and built into the design phase. This preliminary configuration of the tooth profiles ensures that when the components are assembled, the anchor naturally finds its correct rest position without requiring subsequent adjustment operations.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If the anchor rests on external pins in conventional escapements, then rest positions are defined, but the system requires adjustment to compensate for manufacturing tolerances

Engineering Contradiction:
Improveanchor rest position stabilityVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention removes the external adjustment mechanism from the escapement system. Instead of using adjustable components or external pins requiring positioning, the design extracts the adjustment function entirely by incorporating tolerance compensation directly into the geometric parameters of the escapement wheel teeth.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The escapement wheel tooth profiles are designed to automatically compensate for manufacturing tolerances through their geometric configuration. The anchor self-adjusts to the correct rest position through the interaction of the tooth flanks with the pallet rest planes, eliminating the need for external adjustment mechanisms.

Inventive Principle:
Principle #25Self-service

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

This design reduces the need for adjustments, ensuring consistent performance across manufacturing tolerances by allowing the anchor to self-align to a balanced position, enhancing the operational stability and accuracy of the timepiece.

Implementation Method 1

the contact between the anchor and the escape wheel via said at least one driving plane creates a torque which tends to reduce the angle between the lever and the reference axis (V)

Methodology Applied
Scientific EffectTorque: Torque

Data Source

PatentEP2923242B1Lever escapement for a timepiece
Publication Date: 2016.06.15 DETRA
  • EP2923242B1 patent drawingFigure 1
  • EP2923242B1 patent drawingFigure 2
  • EP2923242B1 patent drawingFigure 3

AI summary

The invention concerns a lever escapement for a timepiece in which contact end angles β1 and β2 between the pallets and the escapement wheel are respectively greater than angles of repose δ2 and δ1 of the two rest positions of the lever. This escapement does not require adjustment or a final alteration of the position of the pallets.