Timepiece Display Mechanism Guide Bearing Design
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Solution Overview
Problem
In horological movements, the hands or displays must be precisely guided to avoid touching each other or the dial, while minimizing the inclination due to clearances in the pivots, which affects the chronometric performance and efficiency.
Innovation Solution
A timepiece display mechanism featuring guide bearings with V-shaped support surfaces and elastic holding elements that exert a controlled braking force on the shaft, preventing radial exit and minimizing friction-induced amplitude loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a foil spring is placed on the shaft to prevent hands from bending and touching, then the safety between hands is improved, but the friction torque generated is difficult to control and directly influences the amplitude of the balance wheel, chronometric performance, and efficiency of the mechanism
Solution Approach 1:
The guide device is divided into two separate guide shoulders instead of using a single foil spring. Each guide shoulder provides independent guidance, distributing the guiding function and reducing the friction torque on the shaft while maintaining hand safety.
Solution Approach 2:
The foil spring is extracted and replaced with a rigid guide device comprising guide shoulders. This removes the source of difficult-to-control friction torque while maintaining the essential function of preventing hand bending and contact.
2Reliability
If the distance between the guide shoulders of the shaft is kept short, then the lever arm effect is reduced, but the clearances in the guide pivots still cause significant inclination (more than 50% contribution to decreased safety)
Solution Approach 1:
A rigid guide device with precisely engineered guide shoulders acts as an intermediary between the shaft and the hands. This intermediary compensates for pivot clearances by providing stable, precise guidance that reduces inclination caused by manufacturing tolerances.
3Stability of the object's composition
If multiple leaf springs are used to provide both guiding and braking by friction, then the shaft equilibrium position is maintained through rigidity, but the random orientation of the shaft in the field of gravity makes it more difficult to maintain perpendicularity to plate or bridge
Solution Approach 1:
Instead of using flexible leaf springs that require precise orientation control, the invention uses rigid guide shoulders that inherently maintain perpendicularity through their geometric design. The stability is achieved through the rigid structure rather than flexible elements, inverting the conventional approach.
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 solution effectively prevents hand or display floating and chattering, maintains precise guidance, and minimizes the impact on chronometric properties, ensuring reliable and efficient operation of the horological movement.
Implementation Method 1
exerts on a shaft (3) a resultant elastic force directed towards an axis (D) of rotation of the shaft
Implementation Method 2
The slight friction exerted on the shaft by each holding element (6) ensures braking allowing to avoid any phenomenon of chattering and floating of the display (10)
Data Source
AI summary
A timepiece display mechanism includes at least one display having a shaft, and having at least one plate and/or a bridge carrying at least one guide device for carrying and guiding this shaft around an axis, including, on a first side of said axis, a support surface comprising a V-shape or a pad, symmetrical with respect to a bisector plane passing through the axis, to centre the axis of the shaft on this bisector plane, and on a second opposite side, at least one holding element substantially diametrically opposite the support surface, all the holding elements exerting on this shaft a resultant elastic return force directed towards the axis, and preventing any radial exit of this shaft out of the guide bearing which is a platform with two parallel faces.