This application claims priority from European Patent Application No 15197589.3 of Dec. 2, 2015, the entire disclosure of which is hereby incorporated herein by reference.
The invention concerns a timepiece sub-assembly comprising, on the one hand, a timepiece component made of micromachinable material comprising at least one attachment area, and on the other hand, a shell element arranged to surround said attachment area, said attachment area comprising at least one peripheral contact surface, and said shell element being deformable with a geometry varying between a contracted shape and at least one expanded shape, and arranged to hold said attachment area inside a housing contained in said shell element, and said shell element comprising at least one complementary contact surface arranged, in said contracted shape of said shell element, to exert a clamping force on said at least one peripheral contact surface and to firmly immobilise said attachment area inside said shell element in all directions.
The invention also concerns a timepiece assembly, including at least one receiving component and at least one such sub-assembly.
The invention concerns a timepiece movement including at least one such assembly.
The invention concerns a watch including at least one such assembly.
The invention concerns the field of timepiece mechanisms comprising components made of micromachinable materials.
It is always difficult to assemble micromachinable components to conventional mechanical components in timepiece mechanisms due to sensitivity to shear stress.
EP Patent 2755093 in the name of MASTER DYNAMIC discloses a balance spring collet for a press fit with the shoulder of a timepiece balance wheel, the collet comprising elastically deformable arms, forming an annular space and together delimiting an aperture, each arm comprising a curved concave engagement portion for engagement with such a shoulder, all of the same radius of curvature and equidistant from the central axis, in the free state at a first distance, less than the radius of the shoulder. These engagement portions have a radius of curvature such that, upon deformation of the arm portions, and engagement with the outer surface of the shoulder, the engagement portions substantially conform with the outer surface of the shoulder, and the press fit induced stresses are transferred to and distributed in the arms, so as to prevent any relative movement between the collet and the shoulder upon application of a return force from the balance spring.
EP Patent Application 2743782 A1 in the name of NIVAROX-FAR SA discloses, for timepiece components, a system of assembling a member made of a first material in the aperture of a part made of a second material having no plastic range, using an intermediate portion made of a third material, mounted between said member and said part. This part is received against a first level of the intermediate portion and is resiliently locked on a second level of the intermediate portion by the member in order to make integral the assembly of the member-intermediate portion-part.
The invention proposes to ensure the proper assembly of micromachinable components to conventional mechanical components.
To this end, the invention concerns a timepiece sub-assembly according to claim 1.
The invention also concerns a timepiece assembly, including at least one receiving component and at least one such sub-assembly.
The invention concerns a timepiece movement including at least one such assembly.
The invention concerns a watch including at least one such assembly.
Other features and advantages of the invention will appear upon reading the following detailed description, with reference to the annexed drawings, in which:
The invention concerns a timepiece sub-assembly 10 which comprises, on the one hand, at least one timepiece component 1 made of micromachinable material, and on the other hand, a protective shell element arranged to surround one portion of this component 1.
“Micromachinable material” broadly means any material for obtaining timepiece components made of silicon, silicon oxide, DLC, amorphous material, ceramic, or suchlike, and particularly through the implementation of methods such as MEMS or LIGA, now well known to those skilled in the art. It has been possible to achieve considerable progress in watchmaking, owing to the particularly advantageous features of components made of these materials with these methods: perfect reproducibility, high geometric precision, good, durable elastic characteristics, and it is now possible to produce components of very small dimensions in a repetitive manner. In particular, the fabrication of balance springs, pallet-levers, escape wheels, jumper springs, and balances is well mastered. These technologies also make it possible to reduce in the number of components in an assembly, since they are well suited to the production of one-piece components comprising flexible connections, articulated connections, suspended elements, or suchlike. The production of entirely new types of components has thus also been made possible: this is the case of the very particular, non-limiting application, illustrated by the Figures, to a torsion wire of rectangular cross-section, used as a return element in a balance wheel oscillator. There are, however, limitations on implementation, in particular the difficulty or impossibility of creating shapes in relief and low shear resistance, which limits the application of such components to functions where they are subjected to compression, elongation or torsion stresses. Consequently, holding these components may be difficult in some configurations.
The invention proposes, in particular, to prevent any damage to micromachinable components during mounting in a sub-assembly.
This is why the invention associates a component 1 with an at least partially enveloping shell element 20, whose purpose is to protect component 1 and to absorb in its place any stresses that present a risk of destroying component 1. Shell element 20 is similar to a clamp, which subjects component 1 only to compression forces, which cause no problem.
Preferably, component 1 comprises one area of broader dimensions than the others, which is provided for assembling component 1, and which is referred to as attachment area 2. If no area satisfies this condition, attachment area 2 is simply the section of component 1 which is located in the intended attachment area. The same component 1 may of course comprise several such attachment areas 2, which may take the form of cores.
For example, the median portion of component 1 of
This attachment area 2 in turn comprises at least one peripheral contact surface 3. In a particular embodiment, attachment area 2 also comprises at least one positioning surface 4. Among the various surfaces delimiting attachment area 2, a peripheral contact surface 3 is a junction surface with shell element 20 which, according to the invention, protects component 1 in particular during the assembly thereof. For example, if attachment area 2 is cylindrical, although this shape is difficult to obtain with the aforecited methods in the current state of the art, the peripheral contact surface is a single cylindrical surface. If attachment area 2 is flat, as seen in the other Figures, it comprises two peripheral contact surfaces 3 which are preferably the largest parallel and opposite surfaces, on either side of the thinner area of attachment area 2. Other shapes of attachment area 2 are achievable, and require pressure on more than two surfaces:
Shell element 20 is arranged to hold this attachment area 2 inside a housing 5 comprised in shell element 20, with at least one degree of freedom.
To this end, shell element 20 is deformable, with a geometry varying between a contracted shape and at least one expanded shape. “Deformable” means that the shell element is dimensioned to undergo without damage the relatively small deformations caused by a press fit or similar operation. Shell element 20 is devised to allow for easy insertion of component 1 into an inner housing 5 contained in shell element 20, in an open position corresponding to an expanded shape, which is generally not an unique shape. Shell element 20 is devised to be closed around attachment area 2 of component 1, during the change from the expanded shape to the contracted shape where attachment area 2 is held under pressure. This change from one shape to the other includes a decking step, which corresponds to simply resting shell element 20 on attachment area 2 with no application of force.
The contraction that follows this decking may be derived from an effort (force or moment) inherent to shell element 20, as in
The contraction may also be imposed by interaction with an external component, which compresses shell element 20 around attachment area 2. This is the case of
Shell element 20 advantageously comprises at least one complementary positioning surface 40, which is arranged to cooperate with at least one positioning surface 4, for the precise positioning of attachment area 2 inside such a housing 5, with at least one degree of freedom.
Shell element 20 comprises at least one complementary contact surface 30, which is arranged, in the contracted shape of shell element 20, to exert a clamping force on this at least one peripheral contact surface 3, and to securely immobilise attachment area 2 inside shell element 20 in all directions, by applying a pressure force on attachment area 2.
Preferably, to ensure the proper positioning of attachment area 2 inside housing 5, and then to hold it in the simplest manner, shell element 20 advantageously comprises at least a first element 21 and a second element 22 which move with respect to each other in an expanded shape.
First element 21 and second element or elements 22 (for example, in the example of
Shell element 20 comprises clamping means for holding first element 21 and second element 22 or second elements 22 clamped together in the contracted shape of shell element 20.
In a particular variant, as illustrated in
In a particular variant, shell element 20 forms a sheath comprising a housing 5 for each attachment area 2 of each component 1 comprised in sub-assembly 10, each attachment area 2 being, in the expanded shape, movable in an axial direction inside its respective housing 5, and, in the contracted shape, enclosed in a substantially concentric manner inside housing 5.
In a preferred variant, as seen in
In the variant of
In the variants of
As seen in the variant of
In an advantageously very simple embodiment, each attachment area 2 is plane and comprises two parallel and opposite peripheral contact surfaces 3, and each housing 5 is delimited by two complementary contact surfaces 30 which are parallel and opposite 31, 32.
In the variant illustrated in
In the variant of
Other embodiments may naturally be employed according to the particular geometrical configuration of the components to be held together.
The invention also concerns a timepiece assembly 100, including at least one receiving component 110 and at least one such sub-assembly 10.
Receiving component 110 comprises a receiving chamber 111 for each sub-assembly 10. Inner surface 112 of each receiving chamber 111 is arranged to receive an outer surface 26 comprised in each corresponding shell element 20 of each sub-assembly 10.
Advantageously, at least one inner surface 112 of a receiving chamber 111 is dimensioned to compress the outer surface 26 of the corresponding shell element 20 upon the insertion of the corresponding sub-assembly 10 into receiving chamber 111, to cause shell element 20 to change from its expanded shape to its contracted shape upon said insertion.
Returning to the particular case of
The positioning means 4 represented in
The method of assembly may be summarised as follows:
Component 1 made of micromachinable material, notably silicon, is enveloped in an intermediate component formed by a shell element 20, and the entire assembly is then pressed into a receiving component 110. Component 1 experiences only compression stress during the press fit, but no friction or displacement;
component 1 may comprise guide elements, for obtaining precise positioning;
the intermediate component or components, here the two half-moon portions 21 and 22, may form a self-supporting sub-assembly 10, prior to being pressed into receiving component 10.
The invention also concerns a timepiece movement 200 comprising at least one such assembly 100.
The invention also concerns a watch 300 including at least one such assembly 100.
The principle of the invention is applicable to other configurations of components, such as for example, the assembly of a silicon balance spring stud to a structure, or a silicon fixed pin or suchlike.
In short, owing to the invention, a component made of micromachinable material, notably silicon, can be press-fitted in another element. The invention may also be used for the assembly of certain fragile materials, such as glass, sapphire or suchlike, or for holding very thin microcomponents.
Number | Date | Country | Kind |
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15197589 | Dec 2015 | EP | regional |
Number | Name | Date | Kind |
---|---|---|---|
20130047437 | Daout | Feb 2013 | A1 |
20140064046 | Amano | Mar 2014 | A1 |
20140160901 | Cusin et al. | Jun 2014 | A1 |
20140160902 | Cusin | Jun 2014 | A1 |
20140226447 | Lagorgette | Aug 2014 | A1 |
20160274541 | Amano | Sep 2016 | A1 |
Number | Date | Country |
---|---|---|
2469358 | Jun 2012 | EP |
2 743 782 | Jun 2014 | EP |
2 755 093 | Jul 2014 | EP |
2011116486 | Sep 2011 | WO |
Entry |
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European Search Report dated Jun. 23, 2016, Corresponds to EP 15 19 7589 (5 pages). |
Number | Date | Country | |
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20170160701 A1 | Jun 2017 | US |