Elastic Two-Piece Heart Cam for Reliable Watch Zero Reset
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Solution Overview
Problem
Existing watch mechanisms with heart-shaped cams are prone to quasi-static states and impact marks due to the 'corner-to-tip' position, leading to sluggish zero resets and wear, especially in chronograph mechanisms requiring greater forces.
Innovation Solution
A heart-shaped cam design with a first and second cam component elastically coupled by an elastic element, allowing rotation and displacement to avoid quasi-static positions and reduce impact marks, featuring boundary surfaces for defined movements and a gap for cushioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heart-shaped cam is used with a cam lever to reset the chronograph hand to zero, then the zero reset function is achieved, but impact marks and wear occur on the cam track due to the 'corner-to-tip' position
Solution Approach 1:
The cam is divided into two separate components: a first cam component that is fixed to the rotation axis, and a second cam component that carries the circumferential cam track. These two components are elastically coupled together, allowing them to move independently to some extent. This segmentation allows the second cam component to absorb impacts independently while the first cam component remains stable, thereby reducing wear and impact marks on the cam track.
Solution Approach 2:
An elastic element is introduced between the first and second cam components to provide beforehand cushioning. This elastic element acts as a shock absorber that cushions impacts before they reach the cam track, preventing direct transmission of impact forces that would cause wear and impact marks. The elastic element deforms under impact and then returns to its original position, dissipating the harmful energy.
2Reliability
If the cam lever is pressed against the cam's circumferential track to generate torque for rotation, then the desired zero return is achieved, but a quasi-static state occurs when the corner of the cam lever meets the tip of the heart
Solution Approach 1:
The elastic coupling between the first and second cam components introduces dynamic behavior to the system. When the cam lever presses against the circumferential cam track, the second cam component can move elastically relative to the first cam component, preventing the system from settling into a static quasi-state. This dynamic response allows the mechanism to overcome the corner-to-tip position and continue rotating to achieve the desired zero return.
3Productivity
If greater force is required for zero reset in chronograph mechanisms with linked zero reset for seconds and minutes counters, then the zero reset function is improved, but wear in the form of impact marks increases
Solution Approach 1:
The elastic element provides beforehand cushioning that is particularly beneficial when greater forces are applied during zero reset operations. When the cam lever exerts higher forces to overcome the sluggish winding of linked counters, the elastic element deforms to absorb these increased impact forces, preventing them from being transmitted directly to the cam track. This allows faster, more forceful zero reset operations without proportionally increasing wear and impact marks.
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
Ensures reliable zero resets and minimizes wear on the cam track even under greater forces, maintaining mechanism functionality without additional space or complex components.
Implementation Method 1
a first cam component (1.1), which is fixedly connected to the axis of rotation (1.1.1) of the cam (1), a second cam component (1.2), which carries the circumferential cam track (1.2.1) of the cam (1), and at least one elastic element (1.3). The first cam component (1.1) and the second cam component (1.2) are elastically coupled to one another by means of the at least one elastic element (1.3)
Implementation Method 2
the second cam component (1.2), with the circumferential cam track (1.2.1), can perform a rotation and/or a displacement relative to the first cam component (1.1) in order to avoid a quasi-static position of the cam lever (2) on the circumferential cam track (1.2.1). This ensures reliable zero resets and minimizes wear on the cam track even under greater forces
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2a~2b
AI summary
The present invention relates to a heart-shaped cam for integration into a watch, preferably a wristwatch, wherein the cam has a rotation axis (1.1.1) about which the cam (1) can perform a rotational movement, and a circumferential cam track (1.2.1) which is suitable for cooperation with a cam lever (2), wherein the cam lever (2) is suitable for being pressed against the circumferential cam track (1.2.1) of the cam (1) by means of an applied force. The cam (1) has a first cam component (1.1) which is fixedly connected to the said axis of rotation (1.1.1) of the cam (1), a second cam component (1.2) which carries the said circumferential cam track (1.2.1) of the cam (1), and at least one elastic element (1.3), wherein the first cam component (1.1) and the second cam component (1.2) are elastically coupled to each other by means of the at least one elastic element (1.3) such that the second cam component (1.2) is acted upon when the tip (1.2.2) the heart-shaped cam (1) by the cam lever (2), in which the actuating force exerted by the cam lever (2) from said tip (1.2.2) points to the axis of rotation (1.1.1) of the cam (1), can perform a rotation and/or a displacement relative to the first cam component (1.1) in order to avoid a quasi-static position of the cam lever (2) on the circumferential cam track (1.2.1). The invention also relates to a clock mechanism for controlling at least one function in a clock, which has such a cam, as well as a clock with a corresponding clock mechanism, preferably a wristwatch.