DEVICE FOR GUIDING A SHAFT OF A REST WITH A COIL SPRING

Description

DOMAINE TECHNIQUE

[0001] The invention relates to a device for guiding a rotating shaft of a balance wheel with a spiral spring in a timepiece.

[0002] The invention also relates to a watch movement and a timepiece comprising respectively such a device for guiding a rotating shaft of a balance wheel with a spiral spring. ARRIERE-PLAN TECHNOLOGIQUE

[0003] In watchmaking, it is common to use a balance wheel with a hairspring, which acts as a mechanical oscillator. The oscillation frequency of this oscillator can be adjusted electronically or mechanically by a finishing gear train linked to a mainspring barrel. The pivot at one end of the shaft is typically guided by passing through a circular guide opening, but with some play. This results in imprecise positioning and significant friction, depending on the watch's position, which can quickly wear down the pivot and impair the watch's chronometric accuracy—a significant drawback.

[0004] Document CH 239 786 describes a device for guiding a pivot at one end of the balance staff of a balance spring. The device is arranged with an olive-shaped jewel and a stop inclined relative to the balance staff. The staff is guided without backlash. The friction is thus independent of the watch's position. In a horizontal position, the additional friction of the cylindrical part of the pivot against the olive-shaped jewel is therefore similar to that experienced in a vertical position. However, the amplitude is reduced for all positions, which is a disadvantage for maintaining accuracy.

[0005] It is also known from documents EP 3 258 325 B1 and CH 269 552, the realization of a rotation shaft of a balance spring, in a ceramic material so as to avoid too rapid wear of the ends of the shaft rotating in a guide.

[0006] Document EP 3 382 472 A1 describes a guide bearing for a pivot on the rotating shaft of a balance wheel in a timepiece. A guide bearing may be provided on each side of the ends of the rotating shaft. In one embodiment, the guide bearing may consist of three spirally curved blades evenly spaced from one another. One end of each blade is fixed to a ring coaxial with the rotating shaft, while the other end of each blade contacts one end of the balance wheel's rotating shaft to radially support it. The guide bearing is made of a metallic material. A guide bearing made of a metallic material does not sufficiently reduce the stresses at the contact point between the shaft or the pivot and the shaft.Under these conditions, there is too much energy loss due mainly to friction with the end of the pivot or the rotation shaft, even if the friction no longer depends too much on the orientation of the watch, which is a disadvantage.

[0007] Document CH 705 906 A2 describes a shock-absorbing system for the shaft of a moving part in a timepiece. It includes a pin at one end of the shaft housed in a recess in a shock-absorbing bearing support. However, it does not provide multiple points of contact for the pin to ensure proper centering of the balance wheel's rotation axis.

[0008] It should also be noted that the "open" geometry of the guide bearing does not allow for the retention of the liquid lubrication typically deposited between the bored stone and the counter-pivot stone of a conventional damper bearing. In this case, the oil will migrate along the pivot and then the shaft. Eventually, the pivot will rub "dry" in its bearing, which will further accelerate wear.

[0009] Depending on the orientation of a mechanical timepiece, gravity can affect the operation of the clock mechanism. Document CH 707 501 A2, which describes a clockwork shaft guiding device, provides an example. To prevent excessive angular play in the rotating shaft, at least one pivot at one end of the shaft passes through a jewel with a hole fixed in a bezel and a counter-pivot jewel that has a bearing surface receiving the end of said pivot. The hole in the jewel through which the pivot passes has a diameter substantially larger than the diameter of the pivot itself, allowing it to move very slightly depending on the orientation of the timepiece and, primarily, on gravity.The support stone can be slightly inclined to position the shaft pivot in the hole in the holestone with a small amount of angular play, but without causing excessive angular misalignment at the shaft ends due to gravity. In this case, the shaft is not held in a perfectly centered position. RESUME DE L'INVENTION

[0010] The main purpose of the invention is therefore to overcome the drawbacks of the prior art by proposing a device to guide a rotation shaft of a balance wheel with limited shaft play due to gravity and with a material and geometry of the contact parts of the guide selected to reduce the support forces and therefore the friction forces.

[0011] To this end, the invention relates to a device for guiding a rotation shaft of a balance spring, which includes the characteristics defined in independent claim 1.

[0012] Particular embodiments of the device for guiding a rotation shaft of a balance spring are also described in dependent claims 2 to 21.

[0013] One advantage of the device for guiding the rotating shaft of a balance spring lies in the fact that at least one end of the rotating shaft—for example, at one end of the shaft or at a pivot fixed to one end of the shaft—passes through a guiding opening in a solid body, such as a jewel with a hole. The diameter of the hole is very slightly larger than the diameter of the shaft's end rod or the pivot fixed to the shaft, so as to allow for a slight play.

[0014] According to the invention, at least the contacting parts of the shaft, or of a pivot fixed to the shaft, and of a shaft guide bearing are: made of a material having a Young's modulus less than or equal to 100 GPa in order to reduce friction forces, and / or advantageously made with, or coated with materials whose coefficient of friction between them is less than 0.15, or even 0.1, or even 0.05.

[0015] Preferably, the material can be ceramic, glass, or a filled or unfilled polymer, particularly for the guide blade(s) and for retaining the bearing of the balance wheel's pivot bearing in contact with one end of the balance spring's rotation shaft. In addition to the material chosen, machining must be within a defined tolerance range. The geometry of the blade(s) can also be adapted to minimize the contact area with the end of the shaft or pivot on the shaft.

[0016] The invention also relates to a watch movement, which includes such a device as defined in claim 22.

[0017] The invention also relates to a timepiece which includes such a device as defined in claim 23. BREVE DESCRIPTION DES FIGURES

[0018] The aims, advantages, and characteristics of a device for guiding the rotation shaft of a balance wheel will become clearer in the following description, particularly with regard to the drawings on which: there figure 1 represents a three-dimensional view from above of a balance spring with part of the device to guide the balance spring's rotation shaft, the figure 2 represents a partial cross-sectional vertical side view of the balance spring with the device for guiding the rotation shaft compensating for the effect of gravity according to the invention, the figures 3a, 3b et 3c represent a simplified top view of a first embodiment of a guide bearing for the device to guide the rotating shaft according to the invention, and two cross-sectional views AA of two variant embodiments of the guide bearing, the figure 4 represents a simplified top view of a second embodiment of a guide bearing for the device to guide the rotating shaft according to the invention, the figure 5 represents a vertical side view in cross-section of a device for guiding the rotation shaft of a balance wheel spiral, including, as for the figure 2 at least one solid body with a guide opening, such as a holed stone acting in combination with the guide bearing of the rotating shaft to counteract the effect of gravity according to the invention, and the figure 6 represents a vertical side view in cross-section of the rotation shaft guide device, which consists of a variant embodiment of the guide bearing as shown in the figure 3a and intrinsically linked to a solid body with a guiding opening, such as a holed stone, to form a monolithic structure as an alternative embodiment of the figure 5 . DESCRIPTION DETAILLEE DE L'INVENTION

[0019] In the following description, all the components or elements of the device for guiding the rotating shaft of a balance spring are generally known. These elements or components will therefore only be described briefly. It should first be noted that the device for guiding the rotating shaft of a balance spring also includes the shaft itself, which forms part of a whole with the guiding elements for this shaft and means for mitigating the effects of gravity. Of course, an assembly comprising at least one guide bearing and the rotating shaft of the balance spring can also be used to define the device for guiding the rotating shaft of a balance spring.

[0020] In the following description of the device for guiding the rotation shaft of a balance spring, a guide bearing may be provided, which can consist of contact parts such as flexible blades, for example, for positioning the balance spring axis. This helps to limit unwanted movements of the balance spring when the movement is in a horizontal position. Generally, these movements are responsible for chronometric errors. In an embodiment with flexible blades, these blades center the rotation axis of the balance spring.

[0021] The invention also makes it possible to balance frictional forces between horizontal and vertical positions of the watch movement. Losses due to friction are generally responsible for drops in amplitude and therefore for differences in chronometric accuracy due to the inherent anisochronism of the balance spring system. Equivalent losses, regardless of whether the movement is horizontal or vertical, ensure good precision regardless of its position in space.

[0022] According to the present invention, as described below, a solid body with a guide opening can be used in conjunction with the guide bearing for the balance wheel's rotation shaft. This means that when the movement is in a vertical position, the balance wheel's axis rests within the guide opening of the solid body. This allows the radial displacement of the balance wheel to be mechanically limited beyond the simple stiffness of the blades. Excessive radial displacement is highly detrimental to chronometry.

[0023] According to the present invention, a pivoting system can also be envisioned within an enclosed space, allowing the use of a lubricant, unlike the prior art where an open system is generally incompatible with lubrication. Adding a lubricant minimizes friction losses, offering the advantage of incorporating guide bearing blades that can be stiffer and easier to handle during component assembly.

[0024] As also described later in this invention, there is an advantage in being able to use components made of polymer materials. These components are, for example, made for flexible or elastic blades in a guide bearing or also for coating the contact surfaces of such guide bearings. Instead of flexible or elastic blades or contact surfaces, it is also possible to use an elastomer with friction surfaces made of a material more suitable for friction with appropriate inserts.

[0025] THE figures 1 et 2 represent the balance spring with the device 1 to guide the assembly with the rotation shaft of said balance spring in a simplified manner for the figure 1 and with means of reducing the effect of gravity for the figure 2 The balance spring consists of a rim 12 connected, for example, by three arms 11 to a central rotating shaft 6, and a spiral spring 13, one end of which is connected to a stud (not shown) on a balance bridge. The other end of the spiral spring 13 is fixed directly, or indirectly via a ferrule, to the rotating shaft 6 of the balance spring.

[0026] The device 1 for guiding the rotation shaft 6 of the balance spring includes said rotation shaft 6 and at least one guide bearing 2 preferably located at one end of the rotation shaft 6. Of course, it is quite conceivable to have two guide bearings 2 of the rotation shaft located at the two ends of the rotation shaft in particular to center the rotation shaft 6 around the central axis AC.

[0027] There figure 2 The device 1 fully defines a guide for a rotating shaft 6, incorporating one or more means 10 for reducing the effect of gravity. These means are designed to keep the rotating shaft centered and are located at least at one end of the shaft. Preferably, at least one end of the shaft includes a pivot 6' fixed to, or directly formed from, the shaft on the side of that end. The rod-shaped end of the pivot 6', for example cylindrical, is inserted into an opening in a solid body 15, such as a drilled stone or a holed stone. The solid body 15 with its guiding opening acts as a stop to limit the pivot's travel in the xy plane, which is the plane normal to the AC axis, or, as mentioned below, to limit the angular play.It thus provides a means to reduce the movement of the shaft due to the effect of gravity depending on the orientation of the timepiece, particularly when the timepiece is positioned in a vertical direction.

[0028] The diameter of the opening of the solid body 15 with guide opening, such as a holed stone, is preferably slightly larger than the diameter of the pivot stem 6' so as to permit an angular play of less than 3° possible of the rotating shaft 6, but a radial play which must be small enough to reduce the effect of gravity depending on the orientation taken by the timepiece.

[0029] According to a more advantageous embodiment, the solid body 15 with a guide opening, such as a drilled or holed stone, has its opening centered on the axis AC of the rotating shaft 6. The same is true for the guide bearing 2 of the rotating shaft 6, which can be located on the inner side of the timepiece and below the solid body 15 with the guide opening. The solid body 15 with the guide opening, which can be, for example, a holed stone 15, is in principle held in a bezel 17 housed in a block 19, which is itself fixed to a blank of the timepiece (not shown). The bezel 17 further includes a counter-pivot piece 14 for supporting the end of the pivot 6', which is fixed to or formed from the shaft at the end of the rotating shaft 6. The counter-pivot piece 14 is substantially mounted parallel to the solid body 15 and on the opposite side from the guide bearing 2.This counter-pivot piece 14 can be held in place by elastic means not shown.

[0030] Insofar as two means for reducing the effect of gravity are provided at each end of the rotation shaft 6 or of the pivots 6' fixed to the ends of the rotation shaft 6, each end rod of the rotation shaft 6 or of the pivots 6' passes through the respective through opening of the solid body 15 to eventually come into direct contact with the respective counter-pivot piece 14.

[0031] A solid body 15 with a guide opening can be made of any type of solid material, for example metal, ceramic, or any type of hard material that is easily made or machinable.

[0032] According to the form of execution presented to the figure 2 Two means 10 are provided to reduce the effect of gravity, located at both ends of the rotating shaft, and a guide bearing 2 is mounted at one upper end of the rotating shaft 6, for example, the dial end. Generally, a pivot 6' is formed at each end of the rotating shaft 6 as a single unit with the shaft. However, the pivot 6' can also be fixed to the end of the rotating shaft 6. In both cases, each pivot 6' has a cylindrical end rod to be inserted with a certain clearance into each respective guide opening of the solid body(ies) 15.

[0033] It may also be envisaged to have two guide bearings 2 mounted respectively on each end of the rotating shaft 6, for example at the location of two pivots 6' fixed respectively to the ends of the rotating shaft 6 or formed from the material of the rotating shaft to form a single-piece structure. Each guide bearing 2 is described in more detail with reference to the figures 3 And 4 hereinafter, includes contact and retaining parts of the ends of the rotation shaft given that the rotation shaft 6 linked to the balance spring is always in alternating rotation in normal operation relative to the guide bearing 2 which is fixedly mounted in or on at least one static member, which may be a blank, or preferably the block 19 or even more preferably, the chaton 17.

[0034] At least all contacting parts of the guide bearing 2 and the rotating shaft 6 are advantageously made of a material with a modulus of elasticity (Young's modulus) less than or equal to 100 GPa. Preferably, this material can be ceramic, glass, or a filled or unfilled polymer, and a list of these materials will be given in more detail in the second part of the detailed description. Furthermore, to counteract the effect of gravity, a radial displacement limiting element is necessary, such as a solid body 15 with a guide opening, which could, for example, be a perforated stone to prevent excessive play in the rotating shaft 6 depending on the orientation of the timepiece. It is also preferable to find materials that reduce the coefficient of friction at the contact between these materials for guiding the rotating shaft 6.

[0035] THE figures 3a, 3b et 3c represent a first form of embodiment of the bearing 2 for guiding the rotation shaft 6 linked to the balance spring. The general shape of the bearing 2 for guiding is generally cylindrical on the periphery in order to be housed and fixed in a blank, or the block 19 or preferably, the chaton 17. In a central part of the bearing 2 for guiding, where the guidance and retention of the rotation shaft 6 will take place, there is provided at least one guide blade 3 to come into contact at one of its ends 4 with the rotation shaft 6 or with an added part of the rotation shaft, which may be a pivot.

[0036] According to the invention in this first embodiment, at least one guide bearing 2 comprises, on a first side of the central axis AC, a bearing portion 5, which is a bearing surface 5 of any geometric shape suitable for making point contact or contact along a line of contact with the rotating shaft 6 or the pivot mounted on the rotating shaft. The bearing surface may also be V-shaped, a bushing, or similar, and is arranged to center the axis of rotation of a shaft 6 on a plane bisecting the bearing surface 5. This bearing surface 5 is symmetrical. The same guide bearing 2 comprises, on a second side of the axis of revolution, which is opposite the first side, at least one retaining element 4 at the free end of the blade 3, which is arranged substantially diametrically opposite the bearing surface 5.We understand that the support surface 5, symmetrical with respect to its bisecting plane, comprises two elementary support surfaces, of the V-shaped surface in this case.

[0037] According to the invention, all the retaining elements 3, 4 with the contact surface 40 are arranged to exert on a shaft 6 a resulting elastic restoring force directed towards the central axis AC, and to prevent a radial exit, out of this guide bearing 2, of a shaft 6 inserted axially along the direction of the axis of revolution in this same guide bearing 2.

[0038] However, it should be noted that a single blade 3 with a contact surface 40 to hold the rotation shaft against the V-shaped surface 5 is difficult to produce because, depending on the orientation of the timepiece, the balance spring is too heavy to be held by the single blade provided.

[0039] To the figure 3b The blade 3, up to its free end, has a rectangular cross-section so as to have a flat contact portion 40 in contact with the end of the shaft 6 or the pivot 6' on a line of contact. However, at the figure 3c , at least the free end of the blade 3 has a lenticular section geometry so as to have only one point of contact on the portion 40 in order to reduce friction at the contact end of the rotation shaft 6 or of the pivot mounted on the rotation shaft 6.

[0040] It should be noted that contact between the shaft 6 or the pivot and one or more support parts 5 can be either point contact or contact along a line. For point contact, each support part 5 can be, for example, a domed structure or a portion of a sphere. However, many other structures can be designed to achieve such point contact. For contact along a line, it could also be a cylindrical structure or portion of a support part arranged along an axis parallel to the axis of rotation of the shaft or any other structure. A combination of point contact and contact along a line is possible. Furthermore, any geometric shape can be proposed to achieve point contact or contact along a line with the shaft or the pivot mounted on the shaft.

[0041] For further information on this first embodiment, reference may be made to patent application CH 716 957 A2 in particular paragraph

[0021] to paragraph

[0027] , which describes guide bearings for a time indicator shaft.

[0042] There figure 4 This represents a second embodiment of the guide bearing 2 of the device 1 for guiding the balance spring's rotating shaft 6. This guide bearing 2 may include at least one contact blade 3 and two support portions 5, which are preferably two other contact blades 3. Thus, the guide bearing 2 consists of a peripheral ring and three spiral-shaped blades 3 oriented towards the rotating shaft 6 to make contact with it in order to hold and guide it along the central axis AC. The free end 4 of each blade 3 makes direct contact with the rotating shaft 6 to hold, center, and guide it along the central axis AC. The three blades 3 may have a different shape and cross-section than the spiral blades.For example, each blade is straight, angled, and regularly spaced 120° apart to ensure regular contact with the rotating shaft. It is also possible to have more than three blades in contact with the rotating shaft.

[0043] The guide bearing 2 of this second embodiment can be obtained in monobloc form in a ceramic, glass or polymer material, filled or unfilled, in particular below the limit threshold of the modulus of elasticity less than or equal to 100 GPa and / or have the lowest possible coefficient of friction, for example at least less than or equal to 0.15. Also, the part of the rotation shaft 6 in contact with parts of the guide bearing 2 are made of the same material or a different material or coating fulfilling the conditions defined by the threshold of the modulus of elasticity or having the lowest possible coefficient of friction, for example at least less than or equal to 0.15.

[0044] For further information on this second form of execution, reference may be made to patent application EP 3 396 470 A1 from paragraph

[0018] to paragraph

[0022] .

[0045] There figure 5 represents a form of embodiment of the guiding device for a rotating shaft 6, which is substantially similar to what has already been described in the figure 2 Under these conditions, only the structure or elements that differ from those already described are explained. figure 2 The structure, which is presented, is schematically that of a modified shock absorber with a guide bearing 2 of the guide device 1 according to the invention.

[0046] The guiding device 1 therefore comprises the guide bearing 2, the solid body 15 with guide opening, and the counter-pivot piece 14. The guide bearing 2 is the first element mounted at one end of the rotating shaft 6 or the pivot 6', fixed to or formed from the material of the rotating shaft 6 at its end. The solid body 15 with guide opening is mounted above the guide bearing 2 on the end of the rotating shaft 6 or the pivot 6', while the counter-pivot piece 14 is mounted above the solid body 15 on the opposite side of the guide bearing 2 and above the end of the rotating shaft 6 or the pivot 6'. The guide bearing 2, the solid body 15 with guide opening and the counter-pivot piece 14 are mounted or fixed successively in a chat 17. The chat 17 is housed for example fixedly in a block 19, which is itself fixed to a blank or plate of the watch part not shown.

[0047] To facilitate the assembly of the chaton 17 before its possible fixing in an upper opening of the block 19, the chaton 17 may include a conical peripheral portion to be guided and centered in a complementary conical recess of the block 19. The chaton 17 may also bear against a lower edge of the block 19. The chaton 17 may further include an annular rim at the top surrounded by a cylindrical portion for mounting the counter-pivot stone 14. Finally, this counter-pivot stone 14 may be held in place with the other elements mentioned in the block 19 by elastic means 20, which may be in the form of a split metal ring of the type of retaining spring bearing against an upper edge of the block 19. This split metal ring 20 may serve as the base for the damper of the guide bearing 2 of the guide device 1 according to the invention.

[0048] According to an alternative embodiment presented to the figure 6 , the only difference compared to what was described in the execution form of the figure 5 The key feature is that the guide bearing 2 and the solid body 15 with guide opening form a single-piece structure. This means that the solid body 15 with guide opening and the guide bearing 2 are made of the same material and form a compact, single-piece assembly upon completion. This single-piece structure of the bearing 2 and the solid body 15 with guide opening ensures precise machining and positioning of the guide elements and the guide opening of the solid body, while still allowing for conventional lubrication of the contact elements. In this configuration, the pivoting system, which includes the guide device 1 for a rotating shaft, must be housed within an enclosed space.

[0049] It should also be noted that, in the traditional manner of the components of a shock absorber assembly, the solid body 15 with guide opening is generally driven into the socket 17, while the counter-pivot piece 14 is placed or mounted on an upper part of the socket 17. The annular spring 20 therefore holds the counter-pivot piece 14 and the socket 17 in the block 19.

[0050] For the guide bearing 2, or even for the solid body 15 with guide opening, it may be envisaged to make at least the contact parts in a hard material in order to greatly reduce friction forces.

[0051] The type of ceramics to be used for the guide bearing and / or the rotating shaft can be oxide-based ceramics, mainly alumina and zirconia, or silica.

[0052] Regarding zirconium oxide (ZrO₂), it can be used in yttrium oxide-stabilized zirconia (ZrO₂ + Y₂O₃), which has a metastable tetragonal crystal structure, a grain size less than 0.50 µm, a density greater than 6.00 g / cm³, and a hardness of approximately 1200 HV. Zirconia can also be stabilized with cerium oxide (ZrO₂ + CeO₂) or magnesium oxide ((ZrO₂ + MgO), depending on the desired properties of the final material.

[0053] Regarding Alumina Zirconia, the composites are generally 80% 3Y-TZP / 20% Al 2 O 3 (ATZ) or 90% Al 2 O 3 / 10% 3Y-TZP (ZTA), combining the properties of high-purity aluminas and zirconias to obtain final characteristics that offer the best of each material.

[0054] It should also be noted that the use of hard materials makes it possible to decrease or reduce the contact friction forces of the materials in contact, which may also be desirable.

[0055] From the description just given, multiple variants of the embodiment of the device for guiding a rotation shaft of a balance spring can be designed by a person skilled in the art without departing from the scope of the invention defined by the claims.

Claims

1. Device (1) for guiding a rotary shaft (6) of a sprung balance, the device comprising at least the rotary shaft (6), at least one guide bearing (2) for guiding an end or a pivot (6') fastened to one end of the rotary shaft (6) of the sprung balance, the guide bearing comprising at least one blade (3) and at least one part (5) for coming into contact with and holding the end or the pivot (6') of the rotary shaft (6) of the sprung balance, at least one end part of the rotary shaft (6) or of the pivot (6') of the rotary shaft (6), or at least the contact parts (3, 5) of the guide bearing (2) being made of a material with a Young's modulus of less than or equal to 100 GPa said device comprising means for reducing the effect of gravity depending on the orientation of the device or timepiece comprising it, the means for reducing the effect of gravity depending on the orientation of the device or timepiece comprising at least two solid bodies (15), respectively disposed at the two ends of the rotary shaft (6) to respectively receive, via a guide opening in each solid body (15), each end arbor of the rotary shaft (6) or of a pivot (6') of the rotary shaft (6) along the axis (AC) of the rotary shaft (6) in a centred position, the diameter of the opening in the solid bodies (15) being slightly greater than the diameter of each end arbor of the rotary shaft (6) or of the pivot (6') of the rotary shaft (6) to give the rotary shaft (6) limited angular play as a result of gravity depending on the orientation of the device or timepiece comprising it, characterised in that the means for reducing the effect of gravity further comprise an end-piece (14) disposed at a distance from and parallel to the solid body (15) with a guide opening on a first side of the rotary shaft (6) and another end-piece (14) disposed at a distance from and parallel to the other solid body (15) on a second, opposite side of the rotary shaft (6), each end-piece being capable of being in contact with the end of the rotary shaft (6) or of the pivot (6') of the rotary shaft (6).

2. Device (1) according to claim 1, characterised in that the first solid body (15) with a guide opening and the first end-piece (14) are fastened to a setting (17) parallel to and at a distance from one another on a first, upper side, and in that the second solid body (15) and the second end-piece (14) are fastened to another setting (17) parallel to and at a distance from one another on a second, lower side.

3. Device (1) according to one of claims 1 and 2, characterised in that at least one guide bearing (2) is fixedly mounted in or on at least one static member, which is a blank, or a block (19) or even the setting (17).

4. Device (1) according to claim 3, characterised in that the guide bearing (2) and the solid body (15) with a guide opening are fixedly mounted in a lower part of the setting (17), which is itself fixedly mounted in a recess in the block (19), and in that the end-piece (14) is mounted on an upper part of the setting (17).

5. Device (1) according to claim 4, characterised in that resilient means (20) hold the setting (17) and the end-piece (14) in the recess in the block (19).

6. Device (1) according to claim 5, characterised in that the resilient means consist of a split annular spring to hold the end-piece (14) on the setting (17) and in the recess in the block (19).

7. Device (1) according to claim 1, characterised in that the solid body (15) with a guide opening is made from a hard material, such as a metal or ceramic material, or even in the form of a jewel.

8. Device (1) according to claim 1, characterised in that an end-piece (14) is made from a hard material, such as a metal or ceramic material, or even in the form of a jewel.

9. Device (1) according to claim 1, characterised in that the contact part (5) is a support surface (5) structured so as to have a contact line or contact point against the shaft (6) or the pivot (6') to reduce friction.

10. Device (1) according to claim 1, characterised in that the contact part (5) consists of two contact blades (3) for a total of three contact blades.

11. Device (1) according to claim 10, characterised in that it consists of the three contact blades (3), each of said three blades being coil-shaped, and in that a first end of each blade is fastened to a ring (2) coaxial with the rotary shaft (6), whereas a second end (4) of each blade comes into contact with one end of the rotary shaft (6) of the balance to hold it axially.

12. Device (1) according to claim 10, characterised in that each of the contact blades (3) are rectilinear in shape, and in that a first end of each blade is fastened to a ring (2) coaxial with the rotary shaft (6), whereas a second end (4) of each blade comes into contact with one end of the rotary shaft (6) of the balance to hold it axially.

13. Device (1) according to one of claims 11 and 12, characterised in that all of the blades are evenly spaced 120° apart from one another around the ring.

14. Device (1) according to one of the preceding claims, characterised in that at least one blade (3) or a contact part (5) comprises a contact portion making contact with the shaft (6) or the pivot (6') and formed so as to have only a single point of contact with the shaft (6) or the pivot (6').

15. Device (1) according to one of claims 1 to 13, characterised in that each blade (3) comprises a contact portion making contact with the shaft (6) or the pivot (6') and formed so as to have only a single point of contact in order to reduce friction.

16. Device (1) according to claim 1, characterised in that a contact part of the shaft (6), the contact blade (3) and the contact part (5) are made of the same ceramic, glass or filled or non-filled polymer material.

17. Device (1) according to claim 1, characterised in that a contact part of the shaft (6), the contact blade (3) and the contact part (5) of the guide bearing (2) are made of two different ceramic, glass or filled or non-filled polymer materials.

18. Device (1) according to one of claims 16 and 17, characterised in that the elements of the guide bearing (2) are made in one piece.

19. Device (1) according to claim 1, characterised in that the guide bearing (2) and the solid body (15) with a guide opening form a one-piece structure.

20. Device (1) according to claim 1, characterised in that the coefficient of friction of the materials of the contacting parts or of the coating of the contacting parts is at least less than or equal to 0.1, or at least less than or equal to 0.05, or at least an end part of the shaft (6) or of the pivot (6') or at least the contact parts (3, 5) of the guide bearing (2) being made of a material with a Young's modulus of less than or equal to 100 GPa.

21. Device (1) according to claim 1, characterised in that the contacting parts of the guide bearing (2) and of the rotary shaft (6) or of the pivot (6') of the rotary shaft (6) are lubricated in an enclosed space of the device for guiding the rotary shaft (6).

22. Horological movement, for example a wristwatch, equipped with such a device (1) according to one of the preceding claims.

23. Timepiece, for example a wristwatch, provided with a movement equipped with such a device (1) according to one of the preceding claims.