Chronograph Hand Braking Spring With Intermediate Washer
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Solution Overview
Problem
Existing anti-shake devices for mechanical watch movements, such as chronograph seconds hands, face challenges in controlling and adjusting frictional force, are difficult to install, prone to damage during assembly, and sensitive to vibrations and shocks, leading to inconsistent braking torque.
Innovation Solution
A braking device comprising a braking spring and an intermediate piece, arranged outside the gear train, generates a constant braking torque through radial pressure, allowing easy assembly and adjustment without damaging the spring during assembly, and is less sensitive to vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire spring is used to exert frictional force on the shaft in existing anti-shake devices, then the chronograph hand can be stabilized, but the spring is prone to damage during assembly and adjustment is difficult
Solution Approach 1:
A stationary intermediate piece (washer-like component) is introduced between the wire spring and the shaft. This intermediary component transfers the frictional force from the spring to the shaft while protecting the spring from direct contact with the moving shaft, thereby preventing spring damage during assembly and operation.
Solution Approach 2:
The braking device is divided into separate functional components: the wire spring for generating frictional force, the stationary intermediate piece for force transmission and protection, and the shaft for rotation. This segmentation allows independent assembly and adjustment of each component without risking spring damage.
2Force
If the wire spring is directly pressed against the shaft, then frictional force is generated, but control and adjustment of the frictional force becomes difficult
Solution Approach 1:
The stationary intermediate piece serves as a mediator that allows controlled transmission of frictional force from the wire spring to the shaft. By pressing against this intermediate piece rather than directly against the shaft, the frictional force can be more precisely controlled and adjusted.
Solution Approach 2:
The system allows dynamic adjustment of the frictional force by modifying the pressure exerted by the wire spring on the intermediate piece. The stationary intermediate piece maintains consistent contact with the shaft, enabling stable frictional force control that can be adjusted as needed.
3Reliability
If the braking device is assembled with multiple rivets and intermediate parts, then the friction spring can be secured, but the assembly becomes very difficult and time-consuming
Solution Approach 1:
The stationary intermediate piece acts as a simplified intermediary component that replaces complex multi-rivet assembly structures. This single intermediate component secures the wire spring and transmits force to the shaft, dramatically reducing assembly complexity and time while maintaining reliability.
Solution Approach 2:
Multiple assembly steps and components are merged into a single integrated braking device assembly. The wire spring, intermediate piece, and shaft form a compact unit that can be assembled together in fewer steps, reducing overall assembly time while maintaining secure attachment.
4Productivity
If the spring is superimposed on the grooved washer during assembly, then the seconds hand can be mounted, but the spring may be damaged by radial runout
Solution Approach 1:
The stationary intermediate piece serves as a protective intermediary between the wire spring and the grooved washer/shaft assembly. By pressing against this intermediate piece rather than directly against the grooved washer, the spring is protected from damage caused by radial runout during assembly and operation.
Solution Approach 2:
The stationary intermediate piece provides beforehand protection to the wire spring against radial runout and mechanical damage during the mounting process. This intermediary component absorbs and distributes forces that could otherwise damage the spring, ensuring its integrity throughout assembly and operation.
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 provides a stable and consistent braking torque, easy installation, and protects the spring from damage during assembly, ensuring precise friction control and resistance to shocks.
Implementation Method 1
generate a friction force between the lateral surface and the surface of revolution, which in turn generates the braking torque
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The mechanical watch movement comprises a mainspring barrel, an escapement wheel associated with a mechanical resonator, a display wheel (30) for carrying a display element, in particular a chronograph hand (48), and driven in rotation by the mainspring barrel, and a braking spring (10) arranged to generate, when the latter is subjected to a rotational driving torque, a braking torque intended to prevent vibration of the display element. The mechanical watch movement further comprises an intermediate component, in particular a washer (8), located between the braking spring and a shaft (36) of the display wheel, this intermediate component being freely mounted for rotation on the shaft. The intermediate component and the braking spring are arranged so that the intermediate component remains stationary and does not rotate during normal operation.The brake spring exerts an overall pressure force on the intermediate part in the direction of said shaft in order to generate said braking torque.