Balance Wheel-Hairspring Oscillator Isochronism Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The isochronism of a sprung balance type oscillator in timepieces is disrupted by various factors, leading to non-uniform oscillations and differences in rate and amplitude across different positions, which affects the accuracy of the watch movement.
Innovation Solution
A method that involves determining isochronism curves for a spiral balance type oscillator and modifying the friction coefficients between the pivot ends and their bearings to correct the rate and amplitude discrepancies, specifically by adjusting the horizontal and vertical friction coefficients to minimize the glass-bottom shift, flat-hanging shift, and flat-hanging shift in amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the balance wheel and hairspring assembly is used in traditional configurations, then the structure is simple and manufacturing is easy, but the isochronism is poor and rate varies significantly across different positions
Solution Approach 1:
The patent applies local quality by modifying specific geometric parameters of the balance wheel (rim cross-section, spoke thickness, counterweight distribution) and hairspring (coil spacing, active coil count, attachment geometry) to optimize isochronism. These localized modifications allow the assembly to compensate for positional variations without requiring complete structural redesign, thus improving reliability while maintaining relative simplicity.
Solution Approach 2:
The invention systematically varies geometric parameters including the balance wheel rim thickness profile, spoke dimensions, counterweight positions, and hairspring coil characteristics. By adjusting these parameters, the patent achieves better isochronism performance across six standard positions, demonstrating how parameter optimization can resolve the contradiction between reliability and complexity.
2Loss of energy
If the pivots and bearing surfaces are made smaller to reduce friction, then the friction loss is reduced, but the manufacturing precision requirements increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-lubricating the pivot-jewel interfaces with specific lubricant compositions and quantities before assembly. This preliminary lubrication step reduces initial friction losses and allows for slightly larger pivot dimensions without compromising energy efficiency, thereby relaxing manufacturing precision requirements while still minimizing friction loss.
Solution Approach 2:
The invention introduces lubricant as an intermediary substance between the pivot surfaces and bearing jewels. This intermediary layer reduces direct metal-to-metal contact and friction loss, allowing the use of larger, more easily manufactured pivot dimensions while maintaining low energy loss, thus resolving the contradiction between friction reduction and manufacturing precision.
3Reliability
If the amplitude of oscillations is increased to improve timekeeping accuracy, then the rate stability improves, but the escapement and pivot friction effects become more pronounced
Solution Approach 1:
The patent applies anti-weight by optimizing the balance wheel's counterweight distribution and moment of inertia to compensate for the increased frictional loads generated at higher amplitudes. By carefully balancing the rotational inertia and counterweights, the system maintains stable rate performance even when operating at higher amplitudes where escapement friction is more significant, thus resolving the contradiction between rate stability and friction effects.
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 method improves the isochronism of the oscillator by reducing the differences in rate and amplitude across positions, enhancing the accuracy and stability of the watch movement by optimizing the friction coefficients, thereby minimizing delays and maximizing oscillation amplitude.
Implementation Method 1
a spiral spring attached at its ends to the balance wheel 1 and to the stud 9 itself fixed to the cock
Implementation Method 2
Generally, a lubricant is used to improve the pivoting between the pivots 3, 4 and the pivot jewels 5, 6 and the counter-stones 7, 8
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3~4
AI summary
The present invention relates to a method for correcting the rate and/or amplitude at positions for a balance-spring type oscillator of a watch part in which at least one of the reference friction coefficients between the pivots and the bearings of the oscillator is modified in its horizontal top or horizontal bottom or vertical positions to correct the case back-glass offset in operation and/or the flat-pendulum offset in operation and/or the flat-pendulum offset in amplitude.