HOROLOGICAL OR JEWELLERY HINGE ASSEMBLY

A horological or jewellery hinge assembly including an outer hinge with a first and a second knuckle and an inner hinge with a single knuckle, which pivot about a screw passing through a guide tube insertable and indexed rotatably in the first knuckle and a tube-nut insertable in the second knuckle, and axially immobilised by a head in the guide tube and including a thread cooperating with an internal thread of the tube-nut, for adjusting the axial clearance or tightness between the outer hinge and the inner hinge, the tube-nut being indexable rotatably in the second knuckle, the tube-nut or the guide tube being advantageously made of polyamide or polytetrafluoroethylene or high-density polyethylene.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a horological or jewellery hinge assembly including, on the one hand, an outer hinge with a first knuckle and a second knuckle which are integral with an outer base plate and including respectively a first bore and a second bore which are aligned along an axis, and on the other hand an inner hinge with a single knuckle integral with an inner base plate and insertable, with minimum clearance, between said first knuckle and said second knuckle and including a third bore capable of being aligned along said axis with said first bore and said second bore in an operating position, in which said outer hinge and said inner hinge are mounted so as to pivot relative to each other about a screw, through, on the one hand, a guide tube for said screw intended to be inserted into said first bore and including first angular indexing means intended to cooperate with complementary first angular indexing means that said outer hinge includes at said first knuckle, and, on the other hand, a tube-nut intended to be inserted into said second bore, said screw including a head for its axial immobilisation in said guide tube and a thread intended to cooperate with an internal thread that said tube-nut includes, the cooperation between said thread and said internal thread making it possible to adjust the axial clearance or tightness between said outer hinge and said inner hinge.

The invention relates to the field of articulated fasteners for timepieces or jewellery, and in particular to safety hinges.

TECHNOLOGICAL BACKGROUND

Small hinges are known, including a double-knuckle outer hinge and a single-knuckle inner hinge, where the friction of the hinge can be increased by tightening a hinge screw which holds the outer and inner hinges together, and which forms a pivot guide shaft.

Very small hinges, such as those used in the horological and jewellery industries, with guide body diameters of less than 2 millimetres at the knuckle, often fail to withstand fatigue. The outer hinge typically forms a U shape, and the bending stress zones at the inner vertices of the U often mean that the hinges have to be oversized, which is not always compatible with the horological or jewellery part that includes this hinge.

Furthermore, in addition to bending stresses in a plane passing through the hinge axis, torsional stresses are generated by the cooperation of an axial screw and its nut. Finally, friction in the bores of the knuckles quickly leads to wear that should not be overlooked, especially for top-of-the-range or luxury parts, which can have moving parts made of titratable materials, in particular gold and/or platinum alloys, or similar, and bear precious stones or other gems.

The aim is to ensure the long-term operational reliability of such a hinge.

SUMMARY OF THE INVENTION

The purpose of the invention is to provide a hinge of very small dimensions, intended to resist bending, torsion and wear, and to be perfectly reliable for the user.

To this end, the invention relates to a horological or jewellery hinge assembly including, on the one hand, an outer hinge with a first knuckle and a second knuckle which are integral with an outer base plate and including respectively a first bore and a second bore which are aligned along an axis, and on the other hand an inner hinge with a single knuckle integral with an inner base plate and insertable, with minimum clearance, between said first knuckle and said second knuckle and including a third bore capable of being aligned along said axis with said first bore and said second bore in an operating position, in which said outer hinge and said inner hinge are mounted so as to pivot relative to each other about a screw, through, on the one hand, a guide tube for said screw intended to be inserted into said first bore and including first angular indexing means intended to cooperate with complementary first angular indexing means that said outer hinge includes at said first knuckle, and, on the other hand, a tube-nut intended to be inserted into said second bore, said screw including a head for its axial immobilisation in said guide tube and a thread intended to cooperate with an internal thread which said tube-nut includes, the cooperation between said thread and said internal thread making it possible to adjust the axial clearance or tightness between said outer hinge and said inner hinge.

According to the invention, said tube-nut includes second angular indexing means arranged to cooperate with complementary second angular indexing means that said external hinge includes at said second knuckle.

Another aspect of the invention relates to the manufacture of the tube-nut and/or of said guide tube from polyamide 11 or polyamide 6-6 or polytetrafluoroethylene or high-density polyethylene.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a diagrammatic representation of a watch or jewellery hinge assembly100according to the invention.

This hinge assembly100includes, on the one hand, an outer hinge1with a first knuckle11and a second knuckle110which are integral with an outer base plate10and including respectively a first bore12and a second bore120which are aligned along an axis D, and, on the other hand, an inner hinge2with a single knuckle21integral with an inner base plate20and insertable, with minimal clearance, between the first knuckle11and the second knuckle110.

This single knuckle21includes a third bore26which is able to be aligned along the D axis with the first bore12and the second bore120in an operating position, in which the outer hinge1and the inner hinge2are mounted so as to pivot relative to each other about a screw5, through, on the one hand, a guide tube4for the screw5arranged to be inserted into the first bore12, and, on the other hand, a tube-nut3arranged to be inserted into the second bore120.

The guide tube4includes first angular indexing means43, which are arranged to cooperate with complementary first angular indexing means13included in the external hinge10at the first knuckle11. The screw5has a head51for immobilising it axially in the guide tube4, and a thread55which is arranged to cooperate with an internal thread35in the tube-nut3. The cooperation between the thread55and the internal thread35makes it possible to adjust the axial clearance or tightness between the outer hinge10and the inner hinge20. More particularly, the head51of the screw5has a flat bearing surface52, which is arranged to abuttingly cooperate with a counterbore42formed at the bottom of a recessing41, around the bore44formed for the passage of the screw5in the guide tube4. Preferably, in the operating position, the outer surface of the screw head51is set back from, or flush with, the front face of the guide tube4, and this front face of the guide tube4is itself set back from, or flush with, a first front face17of the outer hinge1. Similarly, a front face37of the tube-nut3is also set back from, or flush with, a second front face117of the outer hinge1. In the free state, without the screw, a first inner front surface48of the guide tube4is distant from a second inner front surface38of the tube-nut3; any contact between them when the screw5is tightened in the internal thread35prevents any damage to the hinge, by preventing further tightening.

According to the invention, the tube-nut3includes second angular indexing means33, which are arranged to cooperate with complementary second angular indexing means133included in the outer hinge10at the second knuckle110.

More particularly, the guide tube4includes first axial stop means430, which are arranged to cooperate with complementary first axial stop means130included in the outer hinge10at the first knuckle11.

More particularly, the guide tube4includes a first cylindrical body46insertable into the first bore12in the first knuckle11, and the first angular indexing means43include a first radial boss of the guide tube4, and project radially relative to the first cylindrical body46, and are arranged to cooperate with a first radial notch in the first knuckle11which the complementary first angular indexing means13include.

Even more particularly, the first radial boss carries the first axial stop means430at the front, and the complementary first axial stop means130of the first knuckle11include a first front bearing surface at the inner end of the first radial notch in the first knuckle11, which notch is blind.

More particularly, the tube-nut3includes a second cylindrical body36insertable into the second bore120in the second knuckle110, and the second angular indexing means33include a second radial boss of the tube-nut3, and project relative to the second cylindrical body36, and are arranged to cooperate with a second radial notch in the second knuckle110which the complementary second angular indexing means130include.

More particularly, the tube-nut3includes second axial stop means330, which are arranged to cooperate with complementary second axial stop means1300included in the external hinge10at the second knuckle110. Thus, the hinge is more resistant to torsion, which is distributed over the solid areas of the knuckles.

More particularly still, the second radial boss carries the second axial stop means330at the front, and the complementary second axial stop means1300of the second knuckle110include a second front bearing surface at the inner end of the second radial notch in the second knuckle110, which notch is blind.

More particularly, the outer hinge1includes, between the first knuckle11and the second knuckle110, and facing each other, a first lug17projecting axially from a first inner front face19of the first knuckle11and including a first rotational abutment surface14, and a second lug170projecting axially from a second inner front face190of the second knuckle110and including a second rotational abutment surface140. The first rotational abutment surface14and the second rotational abutment surface140are arranged to cooperate, in the abutment position, when the inner hinge2is in the same angular position relative to the outer hinge1, respectively with a complementary first rotational abutment surface24and a complementary second rotational abutment surface240which the inner hinge2includes on either side of the single knuckle21. More particularly, the first lug17includes a first lug guide surface16, arranged to guide the guide tube4, and the second lug170includes a second lug guide surface160, arranged to guide the tube-nut3.

Even more particularly, the first rotational abutment surface14and the second rotational abutment surface140are in the continuation of each other, and the complementary first rotational abutment surface24and the complementary second rotational abutment surface240are in the continuation of each other. More particularly still, the complementary first rotational abutment surface24and the complementary second rotational abutment surface240are formed in a first clearance29and a second clearance290, which respectively limit the angular travel of the first lug17and of the second lug170.

Advantageously, to reduce stress and wear, the tube-nut3and/or the guide tube4is made of polyamide 11 or polyamide 6-6 or polytetrafluoroethylene or high-density polyethylene.

More specifically, the first bore12and the second bore120of the outer hinge1have an inner coating of polyamide 11 or polyamide 6-6 or polytetrafluoroethylene or high-density polyethylene.

More specifically, the third bore26of the inner hinge2has an inner coating of polyamide 11 or polyamide 6-6 or polytetrafluoroethylene or high-density polyethylene.

In short, the hinge can be adjusted by screwing in the screw that passes through it, which makes it possible to adjust the hardness of this brake or mechanical friction, and the special arrangement of the guide tube and tube-nut, which are indexed rotatably, makes it possible to distribute the stresses in the hinge optimally, without exceeding the bending and torsion limits; the choice of a guide tube and tube-nut made of a material with a very low coefficient of friction, or coated with such a material, improves wear resistance.

The result is a very small, highly secure hinge that can be used in high-end timepieces and jewellery.