Snail Cam Eccentric Adjustment for Chronograph Simultaneity

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Solution Overview

Problem

Existing instantaneous chronograph minute counters require fragile and unstable adjustments to ensure perfect simultaneity of the seconds hand zero crossing and the minute rocker beak drop, necessitating complex assembly and modification processes.

Innovation Solution

An adjustment device that allows precise angular positioning of the snail cam on the chronograph seconds axis using an eccentric mechanism, enabling fine adjustment without compromising the snail cam's attachment, ensuring the beak falls exactly when the seconds hand reaches zero.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the snail cam is adjusted by successive approximations during assembly, then the angular position can be fine-tuned to achieve perfect simultaneity, but the fixing of the snail cam on the shaft becomes fragile and unstable

Engineering Contradiction:

Improveangular positioning precisionVSAvoidattachment stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The eccentric is pre-configured on the snail cam during manufacturing, establishing the adjustable angular position capability before assembly. This preliminary preparation allows the snail cam to be securely fixed on the shaft while maintaining the ability to achieve precise angular positioning through the eccentric mechanism, eliminating the need for fragile successive approximations during assembly.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If the snail cam is adjusted by dismantling and modifying during assembly, then perfect simultaneity can be achieved, but the adjustment process becomes complex and time-consuming

Engineering Contradiction:

Improveangular positioning precisionVSAvoidadjustment process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The eccentric mechanism is pre-installed on the snail cam during manufacturing, providing a ready-to-use adjustment mechanism that eliminates the need for complex dismantling and modification processes. The eccentric can be rotated to adjust the angular position of the snail cam relative to the shaft, achieving perfect simultaneity without requiring disassembly of the entire mechanism.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The eccentric mechanism introduces dynamic adjustability to the otherwise static snail cam-shaft assembly. By rotating the eccentric, the angular position of the snail cam can be dynamically adjusted during assembly to achieve perfect simultaneity, and then locked in place, providing both precision and simplicity in the adjustment process.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the snail cam is securely fixed on the shaft, then attachment stability is improved, but the ability to perform fine adjustment is compromised

Engineering Contradiction:

Improveattachment stabilityVSAvoidangular positioning precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The eccentric acts as an intermediary element between the snail cam and the shaft, enabling independent adjustment of the snail cam's angular position without compromising the security of its attachment. The eccentric can be rotated to adjust the angle, and its position can then be locked, providing both stable attachment and precise positioning capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Facilitates precise and stable adjustment of the snail cam's angular position, ensuring simultaneous zero crossing and beak drop without dismantling the mechanism, enhancing the reliability and simplicity of the instantaneous minute counter.

Implementation Method 1

The instantaneous chronograph minute counter wheel operating mechanism 1 is illustrated in figure 1. The minute counter wheel 1 is held between its successive actuations in angular positions determined by a jumper 2. This control mechanism comprises a minute counter rocker 3 pivoted in O having a feeler 4 cooperating with a snail cam 5 mounted on, and driven by, the chronograph axis 6. This chronograph axis 6 carries at its upper end the chronograph seconds hand 7 and is integral with the chronograph wheel 11 and the heart for resetting the chronograph seconds 12.

Methodology Applied

Scientific EffectEccentric mechanism: Eccentric

Data Source

PatentEP1953612B1Device for driving and regulating an instantaneous counter

Publication Date: 2012.06.06 PATEK PHILIPPE SA

Figure 1
Figure 2~3
Figure 4~5

AI summary

The device has a snail cam (5) rotatably driven by a chronograph axle (6) that carries a second hand. A minute counter flip-flop (3) has a sensor (4) on a periphery of the cam, and a driving pawl (8) co-operating with a denture of a minute counter wheel (1) by a pawl spring (9). The cam is mounted by friction on a face of the axle, and has an opening receiving a finger (19) of a crank (20) pivoted in chronograph wheel (11). The cam and the crank are arranged such that an angular displacement of the crank causes an angular displacement of the cam with respect to the axle.