Watch Crown Cam Return Mechanism for Neutral Position Control
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Solution Overview
Problem
Existing watch movement control mechanisms do not efficiently guarantee an automatic return to a neutral position after actuating a function, particularly in rapid corrections, and lack a single control element for independent control of multiple functions.
Innovation Solution
A control element with an automatic return device comprising a first and second tubular cam, coordinated by inclined working surfaces, ensures the crown automatically returns to a neutral position after actuation, allowing both rotary and axial control for different functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cam-core mechanism is used to return the control member to its central position, then the control member can be returned to neutral position, but the mechanism is not efficient enough to guarantee automatic return
Solution Approach 1:
A second cam is introduced as an intermediary element between the control member and the spring. This second cam translates the rotational movement of the first cam into axial movement, which then compresses the spring. The spring subsequently pushes the second cam back, which in turn rotates the first cam back to its initial position, ensuring the control member returns to neutral. This intermediary mechanism provides reliable automatic return while maintaining manageable complexity.
Solution Approach 2:
The invention uses inclined planes on the cams to convert rotational parameters into axial parameters and vice versa. The first cam's rotation is converted to axial movement of the second cam through the inclined working surfaces. The spring then converts axial compression back to rotational movement of the first cam, ensuring reliable return to neutral position through parameter transformation.
2Ease of operation
If a single control element is used for multiple functions, then ease of operation is improved, but the device complexity increases
Solution Approach 1:
The control member is designed with dual functionality: it can be rotated to activate first functions (such as month correction) and pressed axially to activate second functions (such as chronograph reset or flyback). This multi-functional design allows a single control element to manage multiple watch functions, improving ease of operation while the internal cam-spring mechanism manages the complexity of coordinating these different actions.
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
Enables reliable automatic return to a neutral position after function actuation, facilitating independent control of multiple watch functions through a single control member, enhancing user convenience and functionality.
Implementation Method 1
cooperate with a spring provided in the guide tube, said first and second cams having working surfaces arranged to be in contact at least when the crown is in its neutral position
Data Source
Figure 1~2
Figure 3~6
Figure 7a~7c
AI summary
The present invention relates to a member (1) for controlling at least one function of a timepiece movement, comprising a crown (2) comprising a head (6) and a central rod (10) rigidly connected to the head (6) and intended to be rigidly connected to a control rod, and a guide tube (4), having a longitudinal axis A, in which the central rod (10) is mounted such that it can rotate axially according to the axis A, the crown (2) being arranged such that it can rotate axially in at least one direction between at least one stable, neutral, angular position and at least one unstable, angular actuation position in which the first function can be actuated via the control rod. The control member (1) comprises a device for automatically bringing the crown (2) from its actuation position back to its neutral position, comprising a first tubular cam (30) mounted around the central rod (10) such that it is rigidly connected thereto, and a second tubular cam (32) which is housed inside the guide tube (4), and is mounted such that it can freely translate axially on the central rod (10) and arranged so as to be able to essentially slide axially within the guide tube (4) and to cooperate with a spring (34) provided in said guide tube (4), the first and the second cam (30, 32) having working surfaces (30a, 32a) arranged to be in contact with one another at least when the crown (2) is in its neutral position, the working surfaces (30a, 32a) having a profile obtained by having at least one plane inclined on the axis A intersect the first and second cams (30, 32) such that, by the cooperation of the working surfaces (30a, 32a), an axial rotation of the first cam (30) via a rotation of the crown (2) into its actuation position results in an axial translation of the second cam (32), compressing the spring (34), and such that an axial translation of the second cam (32) returned by the spring (34), when the rotation into the actuation position ceases, results in an axial rotation of the first cam (30), which automatically returns the crown (2) to its neutral position. The present invention also relates to a timepiece comprising at least one such control member.