Chronograph Friction Wheel Eliminates Jump
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Solution Overview
Problem
Conventional chronograph mechanisms face challenges in minimizing the jump of the chronograph hand during time measurement due to complex designs and inefficient force transmission between gears, leading to unfavorable impacts on watch movement rate.
Innovation Solution
Incorporating a friction wheel mounted on a shaft within the chronograph gear train, allowing for a kinematic connection between the drive and display components via friction, which enables smooth operation and reduces misalignment issues between gear teeth, eliminating the need for a friction spring and improving force transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a significant backlash is provided between the clutch wheel and chronograph seconds wheel to limit hand jump amplitude, then the jump is reduced, but a friction spring is required to prevent quavering and the mechanism becomes more complex
Solution Approach 1:
The patent removes the friction spring component from the chronograph seconds mobile by providing sufficient backlash between the clutch wheel and chronograph seconds wheel. This extraction of the unnecessary component simplifies the device while maintaining hand stability through the backlash mechanism alone.
Solution Approach 2:
The patent segments the clutch device into distinct components (clutch wheel, chronograph seconds wheel, and backlash space) that can function independently. This segmentation allows the backlash to serve as the primary stabilization mechanism without requiring the additional friction spring component.
2Reliability
If triangular profile toothings are provided on the clutch wheel and chronograph seconds wheel to respond to jump and quavering problems, then the mechanical connection is improved, but force transmission becomes mediocre and impacts the watch movement rate
Solution Approach 1:
The patent modifies the tooth profile parameter from triangular to cycloidal or involute profile. This parameter change improves force transmission efficiency between the wheels, reducing negative impact on the watch movement rate while maintaining reliable mechanical connection and eliminating the need for friction springs.
3Ease of operation
If complex constructions with differential gears are implemented to improve chronograph operation, then the operational problems are addressed, but the device becomes more complex and costly
Solution Approach 1:
The patent removes the differential gear construction from the chronograph mechanism by utilizing sufficient backlash between the clutch wheel and chronograph seconds wheel. This extraction simplifies the device construction while maintaining smooth chronograph operation through the backlash-based jump limitation mechanism.
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
The solution effectively prevents the chronograph seconds hand from jumping during start-up and reduces the impact of misalignment, maintaining accurate time measurement without the need for a friction spring, thereby enhancing the watch movement's efficiency and stability.
Implementation Method 1
one wheel set among the driving, transmission and driven wheel sets comprises a friction wheel, frictionally mounted on the shaft corresponding and arranged to cooperate with the wheel of another mobile among the drive, driving, transmission and driven mobiles, the kinematic connection integrating the friction wheel in such a way that the drive mobile and the display are likely to be connected to each other via a friction
Data Source
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AI summary
The present invention relates to a chronograph mechanism, for a watch movement (1), comprising a driving wheel capable of being driven in rotation by a driving wheel to ensure the drive on demand of a driven wheel (10, 20) by means of a transmission wheel (38, 42, 142), the driven wheel (10, 20) being intended to control the movements of a display element, each of the driving, driving, transmission (38, 42, 142) and driven (10, 20) wheels comprising a shaft (72, 78, 82) integral with a first wheel (11, 40, 68). At least one of the driving, transmission (38, 42, 142) and driven (10, 20) mobiles has a second wheel (70, 76) mounted by friction on the corresponding shaft (72, 78) and arranged to cooperate with the first wheel (11, 21) of another mobile (10, 20) among the driving, transmission (38, 42, 142) and driven (10, 20) mobiles.