Shock-Resistant Chronograph Coupling Device with Locking Cam
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Solution Overview
Problem
Chronograph coupling devices in timepieces are prone to inadvertent disengagement due to shocks or sudden movements, which can disrupt the measurement process by causing the coupling lever to move out of its specified positions, leading to interrupted entrainment of the chronograph wheel.
Innovation Solution
A coupling device with a movable element that can assume two specified positions, featuring a control cam, a locking element integral with the cam, and an intermediate arm with a hook mechanism that prevents the movable element from leaving its position under shock, ensuring the coupling wheel remains meshed with the chronograph wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coupling lever is designed to be movable between coupled and uncoupled positions, then the chronograph can be started and stopped, but the coupling lever may inadvertently move due to shocks or sudden movements
Solution Approach 1:
The patent applies preliminary anti-action by introducing a locking element that proactively prevents the coupling lever from moving in response to shocks before the shock can cause disengagement. The locking element engages with the control cam to mechanically block any unintended movement of the coupling lever, counteracting the harmful effect of shocks before they can disrupt the chronograph operation.
Solution Approach 2:
The locking element serves as an intermediary between the control cam and the coupling lever. It mediates the interaction by providing a mechanical connection that translates the position of the control cam into a locking action, thereby stabilizing the coupling lever's position while still allowing controlled movement when needed for operation.
2Reliability
If the return force of the control spring is increased to prevent inadvertent movement, then the coupling lever becomes more stable, but the device complexity increases
Solution Approach 1:
The locking element operates on a self-service principle by automatically engaging and disengaging based on the position of the control cam without requiring external control or adjustment mechanisms. The system uses the existing motion of the control cam to drive the locking element into and out of its locking position, eliminating the need for additional springs, adjusters, or complex control mechanisms.
3Reliability
If a locking mechanism is added to prevent coupling lever movement under shock, then measurement reliability improves, but the device complexity increases
Solution Approach 1:
The locking element is merged with the control cam structure, integrating the locking function into an existing component rather than adding a separate, independent locking mechanism. This integration allows the control cam to serve dual purposes: controlling the coupling lever position and activating the locking element, thereby reducing overall device complexity while maintaining measurement reliability.
Data Source
AI summary
A shock absorbing coupling device for a timepiece, includes a coupling wheel (2) able to take a coupled position and an uncoupled position, a coupling member (1) bearing the coupling wheel and a coupling cam (6) engaging with the coupling member (1) to define the coupled position and uncoupled position of the coupling wheel (2). The device also includes a locking member (12) rigidly attached to the coupling cam (6) and an intermediate member (9) controlled by the coupling member (1). The intermediate member (9) is intended to engage with the coupling member (1) and the locking member (12) to prevent or limit the movement of the coupling member (1) under the effect of a shock when the coupling wheel (2) is in the coupled position, to thus avoid the coupling wheel (2) leaving the coupled position.