Chronograph Zero Reset Mechanism Using Non-Radial Cam Force
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Solution Overview
Problem
Existing chronograph mechanisms require complex adjustments for synchronizing the actuation of hammers and positioning of heart-shaped cams to reset counters to zero, making the process delicate and prone to errors.
Innovation Solution
A display mechanism with a zero reset function, featuring a snail-shaped cam and a feeler-spindle that applies a non-radial return force to return wheels to a predefined position, eliminating the need for hammers and heart-shaped cams by using a decoupling lever to facilitate zero reset, and an instantaneous drive system that includes a driving wheel, arming wheel, and driving finger to drive counter wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hammers and heart-shaped cams are used to reset counters to zero, then the zero reset function can be achieved, but complex adjustments for synchronizing the actuation of hammers and positioning of heart-shaped cams are required
Solution Approach 1:
The patent extracts and eliminates the heart-shaped cam mechanism from the chronograph system. Instead of using a heart-shaped cam to reset the counter, the invention employs a simpler cam profile combined with a feeler-spindle that automatically returns the counter to zero without requiring the complex synchronization adjustments previously needed for hammer actuation and heart-shaped cam positioning.
Solution Approach 2:
The cam in the patent serves multiple functions: it drives the counter wheel during normal operation and simultaneously provides the reset function through its interaction with the feeler-spindle. This multi-functionality eliminates the need for separate reset mechanisms and their associated synchronization adjustments, thereby reducing device complexity while maintaining reliability.
2Measurement precision
If complex synchronization adjustments are made for hammer actuation, then accurate zero reset can be achieved, but the process becomes delicate and prone to errors
Solution Approach 1:
The feeler-spindle mechanism is designed to automatically return the counter to zero through its interaction with the cam profile. This self-service mechanism eliminates the need for manual synchronization adjustments of hammer actuation, making the system easier to operate and less prone to errors while maintaining accurate zero reset functionality.
Solution Approach 2:
The cam profile is pre-designed with specific geometric features that automatically guide the feeler-spindle to return the counter to zero at the appropriate moment. This preliminary design of the cam geometry eliminates the need for delicate field adjustments, making the system both accurate and easy to operate.
3Loss of information
If multiple counter wheels are used for chronograph display, then comprehensive time information can be displayed, but the positioning and coordination of these wheels becomes complex
Solution Approach 1:
The patent divides the chronograph display into separate counter wheels for different time units (seconds, minutes, hours), each with its own simplified cam and feeler-spindle mechanism. This segmentation allows each wheel to be independently controlled and reset, reducing the overall coordination complexity while maintaining comprehensive time information display.
Solution Approach 2:
The patent employs dynamic cam profiles that automatically adapt to the position and state of each counter wheel. The feeler-spindles dynamically interact with their respective cams to ensure proper positioning and resetting of each wheel without requiring complex static coordination mechanisms, thereby simplifying the overall system while maintaining accurate time display.
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
Simplifies the zero reset process by eliminating the need for complex adjustments, ensuring accurate and efficient resetting of chronograph hands to zero without disturbing the movement, and allows for coaxial display of chronometered time information.
Implementation Method 1
the feeler-spindle and the perimeter of the cam are adapted and sized so that the feeler-spindle applies on the cam, in the second state, a return force having a non-radial component adapted to return the first wheel to the predefined position
Data Source
AI summary
A display mechanism a wheel carrying, constrained to rotate with it, a first wheel and a snail-shaped cam, the mechanism having an active first state in which the first wheel is driven in rotation by a driving wheel and a zero reset second state in which it is no longer driven to allow it to return to a predefined position, associated with a predefined position of the display member, the display mechanism further including a feeler-spindle adapted to cooperate with the perimeter of the cam, the feeler-spindle and the perimeter of the cam being adapted and sized so that the feeler-spindle exerts on the cam, in the second state, a return force having a non-radial component adapted to return the first wheel to its predefined position.