Timepiece Oscillator Cage for Spiral Spring Protection

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Solution Overview

Problem

Existing mechanical oscillators in timepieces are prone to deformation and potential attachment to other components upon impact, with existing protective shells being overly large and lacking clear assembly details, and not effectively preventing spiral spring deformation from causing mechanical issues.

Innovation Solution

A mechanical oscillator design featuring a protective cage with an open second face, circular passages for the balance shaft and spiral spring support, and a stud holder allowing circular movement, reducing size while isolating the spiral spring radially and axially, and optionally made in multiple parts for optimized assembly and magnetic protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a protective shell completely encloses the balance and spiral spring, then aerodynamic disturbances are prevented, but the overall size of the mechanical oscillator becomes large

Engineering Contradiction:

Improveaerodynamic disturbancesVSAvoidsize of mechanical oscillator

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The invention extracts only the essential protective function needed - preventing spiral spring deformation and contact with other components - rather than completely enclosing the balance assembly. The protective cage is positioned specifically to contain the spiral spring without requiring full enclosure of the balance wheel, thus reducing overall size while maintaining protection against the most critical harmful effects.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The protective cage applies protection locally where it is most needed - around the spiral spring - rather than uniformly enclosing the entire balance assembly. This localized approach prevents aerodynamic disturbances and impact damage to the spiral spring without requiring a large-volume complete enclosure, resolving the contradiction between protection and size.

Inventive Principle:

Principle #3Local quality

2Reliability

If the protective cage completely encloses the spiral spring, then the spiral spring is protected from impact, but the device complexity increases

Engineering Contradiction:

Improveprotection against impactVSAvoidstructure of protective cage

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective cage is segmented into a minimal set of components - a cylindrical wall and two planar faces - rather than being a complex complete enclosure. This segmentation allows the cage to provide necessary impact protection while maintaining structural simplicity and ease of assembly, resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of creating a complex complete enclosure, the invention inverts the approach by using an open-cage structure with strategic openings. The cage has openings on its second face and in its cylindrical wall to accommodate the balance shaft and spiral spring support, respectively. This inverted approach - protecting through selective containment rather than complete enclosure - reduces structural complexity while maintaining impact protection reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If the protective cage has openings for balance shaft and spiral spring support, then assembly is simplified, but the spiral spring may contact other components

Engineering Contradiction:

Improveassembly of protective cageVSAvoidisolation of spiral spring

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The cylindrical wall of the protective cage acts as an intermediary barrier between the spiral spring and other movement components. While openings are provided for the balance shaft and spiral spring support to facilitate assembly, the cylindrical wall maintains radial isolation, preventing the spiral spring from contacting other components during operation or impact, thus resolving the contradiction between ease of manufacture and reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP2987035B1Mechanical oscillator for a timepiece movement

Publication Date: 2017.03.22 BALL WATCH COMPANY

AI summary

The present invention concerns a mechanical oscillator (1), for a timepiece movement, comprising a balance (14) combined with a spiral spring (16), and a balance bridge (2) carrying a bush (8) in which there pivots one end of a balance shaft (12), to which said balance (14) and a first end of the spiral spring (16) are rigidly connected, a support (18) for holding the second end of the spiral spring (16), and a protection cage (26, 126) for protecting the spiral spring (16) comprising a substantially planar first face (28), rigidly connected to the balance bridge (2), and a substantially cylindrical wall (32) arranged at the periphery of the spiral spring (16). The protection cage (26, 126) is open on the second face (30), positioned facing the balance (14), and has first and second openings (34, 36) provided in the first face (28) to define respective passages for the balance shaft (12) and for the support (18).