Timepiece Transmission Mechanism for Parallel Stems

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Solution Overview

Problem

Existing transmission mechanisms for rotary movements between parallel stems in timepieces are complex, bulky, and difficult to assemble, making them unsuitable for small inter-axial distances and visually unsatisfactory due to eccentricity issues.

Innovation Solution

A transmission mechanism with sliding elements and slide-ways having complementary T-shaped cross sections that allow engagement and disengagement only in their respective sliding planes, enabling axial translation and constant-velocity rotary movement transmission between two parallel stems, which can handle various axial offsets without the need for gearwheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gearwheels are used to transmit rotary movement between parallel stems, then the mechanism can handle large inter-axial distances, but the mechanism becomes complex, bulky, and difficult to assemble

Engineering Contradiction:

Improveability to handle inter-axial distancesVSAvoidmechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional gearwheel mechanical system with a cam-based mechanism. The cam profile is designed to convert rotational movement between offset axes directly, eliminating the need for complex gearwheels while maintaining the ability to handle various inter-axial distances. This substitution reduces device complexity and assembly difficulty while preserving adaptability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a cam with a specifically designed profile where the radial distance from the cam center varies according to a predetermined function. By changing the cam profile parameters, the mechanism can adapt to different inter-axial distances without requiring different gearwheel configurations, thus reducing complexity while maintaining versatility.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If gearwheels are used to correct inter-axial distances, then the transmission function is achieved, but the mechanism is bulky and visually unsatisfactory due to eccentricity

Engineering Contradiction:

Improvetransmission functionVSAvoidmechanism volume

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The cam-based mechanism replaces bulky gearwheels with a compact cam and follower system. The cam profile inherently compensates for eccentricity through its geometric design, providing reliable transmission while occupying minimal space and maintaining a clean visual appearance without visible eccentric components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If gearwheels are used for transmission, then the mechanism can function, but it is difficult to assemble

Engineering Contradiction:

Improvetransmission functionVSAvoidassembly ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The cam-based mechanism replaces multi-component gearwheel assemblies with a single cam component and simple follower. This substitution dramatically simplifies assembly procedures while ensuring reliable transmission through the precisely engineered cam profile that inherently maintains proper alignment and timing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8282271B2Timepiece

Publication Date: 2012.10.09 ROLEX SA

AI summary

This timepiece has a case (8) enclosing a horological movement (10), and a transmission mechanism for transmitting constant-velocity rotary movements between two stems (1a, 1b) on parallel axes, connecting the outside of the case (8) to the horological movement (10) through a hole in the case (8). The adjacent ends of the two stems (1a, 1b) are connected to two respective sliding elements (3, 6) having defined cross sections engaged with two respective slide-ways (4, 7) having cross sections complementary to those of the sliding elements, having sliding planes perpendicular to said axes, the two slide-ways (4, 7) being connected to a common linking member (5) and being oriented at an angle of 90° to each other.