Bistable Hammer for Chronograph Reset Mechanism
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Solution Overview
Problem
Existing chronograph mechanisms are complex and require indirect pusher connections, making them less reliable and prone to accidental hammer release during accelerations, which complicates the operation and reliability of the mechanism.
Innovation Solution
A chronograph mechanism with a hammer that has two articulated arms and studs sliding in slots, allowing for direct actuation and deactivation by separate pushers, and a bistable jumper for stable positions, optimizing movement and stability through elastic triggers and anti-shock devices to manage excessive forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hammer is mounted elastically with indirect pusher connections, then the mechanism can reset the indicator device, but the system becomes complex and prone to accidental hammer release during accelerations
Solution Approach 1:
The hammer is divided into two separate arms (first arm and second arm) that can be independently actuated by different pushers. The first arm carries the first stud actuated by the first pusher, while the second arm carries the second stud actuated by the second pusher. This segmentation allows direct control of each hammer position by dedicated pushers, eliminating complex indirect connections and improving reliability during accelerations.
Solution Approach 2:
Two tenons serve as intermediary elements that translate the linear motion of the studs into rotational motion of the hammer arms. The first tenon connects the first stud to the first arm, and the second tenon connects the second stud to the second arm. These intermediaries enable direct actuation while maintaining mechanical advantage and control precision.
2Reliability
If the pawl exerts high force to release the hammer, then the hammer can be reliably activated, but it may accidentally release during accelerations
Solution Approach 1:
Different regions of the hammer mechanism have different force characteristics. The first arm and second arm are independently controlled with different force levels by their respective pushers. The first pusher activates the first arm with sufficient force to overcome the pawl engagement, while the second pusher controls the second arm with minimal force for reset. This local differentiation of force application prevents accidental releases while ensuring reliable activation.
Solution Approach 2:
Instead of using a single hammer that must be forcefully released from a latched position, the invention inverts the approach by using two independently controlled hammer arms. The first arm is activated only when needed (by the first pusher), while the second arm is controlled separately (by the second pusher). This inversion of the control logic eliminates the need for high-force release mechanisms that cause accidental releases during accelerations.
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 simplifies the chronograph mechanism's operation, enhances reliability by allowing direct pusher actuation, and protects against accidental hammer release during accelerations, ensuring stable and accurate timekeeping.
Implementation Method 1
each movement of the hammer rocker is terminated by the elastic trigger of the jumper
Implementation Method 2
a hammer rocker intended to move the hammer from its active position to its inactive position
Implementation Method 3
the hammer rocker cooperates with a jumper of the bistable type making it possible to make each of the two positions of the hammer stable
Implementation Method 4
the hammer comprises two studs mounted to slide in slots
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a chronograph mechanism (7) comprising an elapsed time indicator (17), a reset control element (21), and a reset device (25) for said indicator comprising a hammer (61) mounted for translation between an inactive position where the hammer (61) is away from cores (55, 57, 59) connected to the indicator (17) and an active position where stops (54, 56, 58) of said hammer exert a reset force against said cores. According to the invention, the hammer (61) has two pins (64, 66) mounted for sliding in slots (100, 102) such that the displacement vectors (L, K) of the pins (64, 66) between said positions are collinear and not aligned. The invention relates to the field of chronographs.