Balance wheel with light inertia adjustment elements for watch movements

Abstract

The present invention relates to a balance wheel for integration into a regulating organ of a clockwork mechanism, comprising a rim (1), spokes (2a, 2b) and a pivot axis (4), wherein the rim (1) is connected to the pivot axis (4) of the balance wheel via the spokes (2a, 2b) and is made of at least one first material, and wherein the balance wheel has a plurality of adjustable inertia adjustment elements (6). The balance wheel is characterized in that the entirety of the inertia adjustment elements (6) is made of a second material, wherein the volume mass of the second material is less than 6 g / cm³.

Description

Field of invention

[0001] The present invention relates to a regulating organ of a watch, in particular to a balance wheel for integration into a regulating organ of a watch movement, which has a rim, spokes and an oscillating axis, wherein the rim is connected to the oscillating axis of the balance wheel via the spokes and is made of at least one first material, wherein the balance wheel has a plurality of adjustable inertia adjustment elements. Background of the invention and prior art

[0002] The balance wheel is the component that, in conjunction with a return spring, such as a spiral spring, regulates the movement of watches, especially wristwatches, through its oscillations. At a frequency of, for example, 4 Hertz, which corresponds to 28,800 semi-oscillations per hour or 14,400 oscillations per hour (where frequency in watchmaking is usually expressed as the number of semi-oscillations per hour in [A / h]), the balance wheel, which can be considered a type of ring-shaped pendulum, must complete eight semi-oscillations per second so that the escapement of the watch movement releases the gear train at the correct intervals and the second hand advances by one step with each release.

[0003] For a mechanical watch to run accurately, the balance wheel's oscillations must be carefully adjusted. Given the manufacturing tolerances of the components, it is standard practice for mass-produced watch movements to measure the moments of inertia of the balance wheel rims and the stiffness of the hairsprings before assembly. These are then sorted and classified according to their deviation from the target values. Based on this, balance wheel rims and hairsprings of matching classes are assembled in a regulating element of the watch movement for the intended oscillation frequency. These components are traditionally sorted into several classes, usually around 20.

[0004] For a mechanical watch with a regulating organ or movement of the type mentioned above to reliably display the time, the balance wheel of the regulating organ must oscillate back and forth uniformly with a calculated or experimentally determined period and amplitude. If there is a rate error, the balance wheel oscillates too fast or too slow, causing the watch to run fast or slow. This can be corrected, among other things, by adjusting the moment of inertia of the balance wheel.

[0005] Therefore, numerous state-of-the-art balance wheels feature adjustable inertia adjustment elements, which allow the moment of inertia of the rim to be set within a specific range. Such inertia adjustment elements are known particularly in the form of weights or screws.

[0006] For example, marine chronometers are known to have movable weights attached to the rim.

[0007] Publication EP 4 194 964 also discloses a balance wheel with four spokes, each having a radially extending gap, in which two pairs of weights are mounted so as to be radially displaceable. One pair has heavier weights for coarse adjustment of the moment of inertia, and the second pair has lighter weights for fine adjustment.

[0008] Many watch movements employ balance wheels of the type mentioned above, whose oscillation frequency can be adjusted using a multitude of regulating screws, usually located on the rim. This adjustment involves changing the position of the screws relative to the rim's axis of oscillation. Turning these screws outwards slows the oscillations, while turning them inwards speeds up the oscillation. Depending on the rate error, the watchmaker determines how to adjust the rim's moment of inertia using these screws.

[0009] Furthermore, conventional balance wheels with a two-metallic rim are known in the prior art. Other balance wheels use a monometallic, uncut rim coupled to a self-compensating spiral spring. These rims also typically feature a multitude of regulating screws arranged around their circumference.

[0010] Up to this point in the prior art, the basic idea was to use screws or weights of the aforementioned type with a high volume mass in order to achieve a high degree of adjustment. The reason for this is, of course, that the greater the mass displaced by a screw or weight, the more significantly it alters the rate of the clock.

[0011] A disadvantage of this method is that an error in adjusting the balance wheel's moment of inertia causes a rate error in the watch movement, which can only be corrected by a watchmaker, thus requiring considerable time. For example, an error of just a few degrees in the rotation of one of the aforementioned regulating screws, when using heavy screws, leads to a significant rate deviation. If, for instance, a pair of steel screws is used to adjust the moment of inertia of a balance wheel of a specific diameter in a state-of-the-art design, each 360° rotation of the screw pair results in a rate deviation of approximately + / - 41 seconds per day; that is, each screw produces a rate deviation of approximately + / - 20.5 seconds per day per rotation. In the case of a 10° error in the angle setting of a regulating screw, this corresponds to a rate deviation of approximately 0.57 seconds per day.Since a balance wheel typically has four or more screws, the overall deviation can be considerable. Fine-tuning to a desired value is therefore a time-consuming and difficult process for a specialist. Object of the invention

[0012] To overcome this disadvantage, an improved balance wheel is therefore desirable. The objective of the present invention is therefore to realize a balance wheel with improved properties with regard to the aspects mentioned above, or to realize a corresponding regulating organ. Inventive solution

[0013] The present invention therefore comprises a balance wheel as its subject matter, which has the features specified in claim 1, as well as a corresponding regulating organ and a clockwork mechanism, which have such a balance wheel. The invention also comprises a method for manufacturing a regulating organ of a clockwork mechanism having such a balance wheel as its subject matter.

[0014] To achieve the aforementioned objectives, the invention is characterized in particular by the fact that the entirety of the inertia adjustment elements is made of a second material, wherein the volume mass of the second material is less than 6 g / cm³.

[0015] By using inertia adjustment elements, especially screws, made of lightweight material, a handling error of a few degrees during the adjustment of the balance wheel's moment of inertia—for example, when turning the screws—results in only a minor rate error of the movement's regulating mechanism. Similarly, by using weights made of lightweight material, a handling error during their adjustment also results in only a minor rate error.

[0016] In specific embodiments of the invention, the inertia adjustment elements are designed as screws or weights, respectively. In one embodiment, the inertia adjustment elements are adjustableally mounted on the rim.

[0017] According to one embodiment, the volume mass of the first material is between 6 g / cm³ and 22 g / cm³, in particular between 6 g / cm³ and 9 g / cm³.

[0018] According to further embodiments, the said first material is selected from among the copper alloys, preferably brass or other copper-zinc alloys (Cu-Zn) and copper beryllium (Cu-Be), preferably with electroplating of precious metal, or from among the gold alloys, in particular the 9ct, 14ct and 18ct gold alloys.

[0019] According to one embodiment, the volume mass of the second material is between 0.5 g / cm³ and 6 g / cm³, in particular between 3 g / cm³ and 5.5 g / cm³.

[0020] According to one embodiment, said second material is a light metal or a light metal alloy, wherein said second material is preferably selected from among the titanium alloys, the aluminum alloys, as well as the magnesium alloys and magnesium-lithium alloys.

[0021] According to further embodiments, the said second material is ceramically refined, preferably by means of a ceramic surface coating of a thickness of less than 10 µm, in particular a thickness of 1 µm to 2 µm, preferably in the form of a coating of Ceratanium.

[0022] According to alternative embodiments, said second material is a ceramic material, wherein said second material is preferably selected from the group of materials containing silicon nitride, aluminum oxide, zirconium oxide and mixtures of aluminum oxide and zirconium oxide.

[0023] According to one embodiment, the entire assembly of inertia adjustment elements consists of four screws arranged radially and offset by 90° on the rim, the total adjustment effect of which is less than ± 140 sec. / day, preferably less than ± 125 sec. / day.

[0024] According to one embodiment, the entirety of the inertia adjustment elements consists of screws whose weight and geometry, including the thread pitch, are selected such that a rotation of a screw by no more than 45°, preferably no more than 30°, causes a change in the rate of the associated clockwork of less than 1 second / day.

[0025] According to one embodiment, a method for manufacturing a regulating organ of a clockwork with such a balance wheel comprises the steps of Provision of a series of balance wheels according to the invention, provision of a series of spiral springs suitable for forming a regulating element of a clockwork with these balance wheels, measurement of the moments of inertia of the balance wheels in said series of balance wheels and of the stiffness of the spiral springs in said series of spiral springs before their installation in a clockwork, sorting and classification of the balance wheels in said series of balance wheels and of the spiral springs in said series of spiral springs according to their deviation from corresponding target values ​​into 30 to 40 balance wheel and spiral spring classes, in particular into 35 balance wheel and spiral spring classes, pairing of a balance wheel and a spiral spring, each selected from corresponding balance wheel and spiral spring classes, assembly of the paired balance wheel and spiral spring into a regulating element of a clockwork. Brief description of the images

[0026] The accompanying illustrations represent an exemplary embodiment of a balance wheel according to the present invention.

[0027] The Figure 1 Figure 1 is a top view of an embodiment of a balance wheel according to the invention; Figure 2 is a partial perspective view of the same. Detailed description of the invention

[0028] The invention will now be described in one of its embodiments with the aid of the aforementioned illustrations. The balance wheel according to the invention is shown schematically and by way of example, although this is not intended to limit the scope of application of the invention in any way.

[0029] The balance wheel shown in Figures 1 and 2 comprises a rim 1 with two spokes 2a and 2b and works in conjunction with a spiral spring 3. The balance wheel 1 can oscillate about the axis of oscillation 4. The balance wheel can, of course, have more than two spokes. The rim 1 has four identical U-shaped indentations 5, each with a radial threaded hole. A screw 6, which serves as an inertia adjustment element, is seated in each threaded hole. Again, it should be noted that the balance wheel can naturally have more or fewer than four indentations 5 and associated inertia adjustment elements or screws 6, and this exemplary description of the invention is not intended to represent any limitation.The latter also applies in the sense that the indentations 5 on the rim 1, in the exemplary embodiment shown in the figures, are only provided to reduce air resistance and the space required for the screws 6, but this is by no means necessary, so that the screws 6 can also be arranged on a circular rim. Figure 2 is a partial view of each indentation 5. As can be seen in Figure 2, the rim 1 has a slot 7 along the indentations 5, the sections of which act resiliently on part of the inertia adjustment elements. The increased friction between the rim 1 and the respective screw 6, caused by this spring action, facilitates handling and stepless fine adjustment of the screws 6 and prevents any loosening or turning of a screw 6 due to vibrations during the oscillations of the balance wheel.

[0030] As illustrated by way of example in Figures 1 and 2, each screw 6 can be turned to the left or right from a central position before it abuts the wall of the rim 1 in its respective recess 5 or the screw head protrudes beyond the outer edge of the rim 1. In total, each screw 6 can be turned by approximately 2.5 to 3 full turns.

[0031] The hoop 1 is made of at least one first material and preferably consists of a commercially available copper alloy, preferably brass or other copper-zinc alloys (Cu-Zn) and copper beryllium (Cu-Be). Alternatively, the hoop 1 can consist of a gold alloy, in particular a 9-carat, 14-carat, or 18-carat gold alloy. Generally, the bulk mass of said first material is between 6 g / cm³ and 22 g / cm³, in particular between 6 g / cm³ and 9 g / cm³. In a preferred embodiment, the hoop 1 has a moment of inertia of 14 mg / cm²; typically, the moment of inertia is in the range of 6 mg / cm² to 18 mg / cm².

[0032] The assembly of inertia adjusting elements 6, i.e., preferably the screws, is made of a second material, preferably a light metal or a light metal alloy. In particular, the second material can consist of a titanium alloy, even more preferably of so-called Ti grade 5, which has a bulk density of 4.5 g / cm³. Alternatively, the assembly of inertia adjusting elements 6 can be made of aluminum alloys, magnesium alloys, or magnesium-lithium alloys. Generally, the bulk density of the second material is preferably less than 6 g / cm³. In particularly preferred embodiments, the bulk density of the second material is between 0.5 g / cm³ and 6 g / cm³, and in very particularly preferred embodiments, the bulk density of the second material is between 3 g / cm³ and 5.5 g / cm³.Furthermore, the aforementioned second material can be ceramically finished, preferably by applying a ceramic surface coating with a thickness of less than 10 µm, in particular a thickness of 1 µm to 2 µm. The coating can be applied in particular in the form of Ceratanium.

[0033] Alternatively, the entire assembly of inertia adjustment elements 6 can be made of a ceramic material, preferably materials based on silicon nitride, aluminum oxide, zirconium oxide, or a mixture of aluminum oxide and zirconium oxide. Finally, the entire assembly of inertia adjustment elements 6 can alternatively also be made of a polymer. In both of these cases, i.e., with inertia adjustment elements 6 made of a ceramic material or of a polymer, the bulk mass of the second material is preferably less than 6 g / cm³.

[0034] For example, one turn of each pair of screws made of grade 5 titanium results in a rate change of + / - 24 seconds per day for a balance wheel with a moment of inertia of 14 mg / cm². For a single screw, the rate change is therefore + / - 12 seconds per day per turn. This corresponds to a rate change of approximately 0.33 seconds per day for a screw angle change of 10°.

[0035] The reduced adjustment effect of lightweight inertial adjustment elements or screws can be compensated for by a higher number of mating classes in the manufacturing process.

[0036] Accordingly, a method for manufacturing a regulating organ of a clockwork with such a balance wheel comprises the following steps: Provision of a series of balance wheels according to the invention, provision of a series of spiral springs 3 suitable for forming a regulating organ of a clockwork with these balance wheels, measurement of the moments of inertia of the balance wheels in said series of balance wheels and of the stiffness of the spiral springs 3 in said series of spiral springs before their installation in a clockwork, sorting and classification of the balance wheels in said series of balance wheels and of the spiral springs 3 in said series of spiral springs according to their deviation from corresponding target values ​​into 30 to 40 balance wheel and spiral spring classes, in particular into 35 balance wheel and spiral spring classes, pairing of a balance wheel and a spiral spring 3, each selected from corresponding balance wheel and spiral spring classes, assembly of the paired balance wheel and spiral spring 3 into a regulating organ of a clockwork.

[0037] For the sake of completeness, it should be mentioned here that the spiral spring 3 can be any type of previously known spiral spring and therefore does not restrict the present invention. In particular, it can be a spiral spring of flat or cylindrical shape, a spiral spring of the Breguet type or of another known spiral spring type, as well as a spiral spring made of metal or metal alloys, of non-metallic material, of inorganic material, and of ceramic material, in particular of material from the carbon-silicon group, preferably of silicon. Example

[0038] A comparison between two types of adjusting screws with identical geometry but different volume masses, for a balance wheel with a moment of inertia of 14 mg*cm 2< shows the following (unless otherwise stated, these are theoretical values): Total adjustment range of a balance wheel with 4 screws, with a class pairing of 20 classes for balance and balance spring, and screws made of 1.4305 steel: ± 205 sec. / day, thus a total adjustment range of 410 sec. / day. Despite this theoretical value, in practice an adjustment range of ± 150 sec. / day is usually used. Total adjustment range of a balance wheel with 4 screws, with a class pairing of 35 classes for balance and balance spring, and screws made of grade 5 titanium: ± 120 sec. / day, thus a total adjustment range of 240 sec. / day. Class range for the balance wheel and balance spring with a class pairing of 20 classes, where the balance wheel is equipped with 4 screws made of 1.4305 steel: ± 79 sec. / day. Class width for the balance wheel and the balance spring in a class pairing with 35 classes, where the balance wheel is to be equipped with 4 screws made of grade 5 titanium: ± 46 sec. / day. Required adjustment range or...The manufacturer-guaranteed rate tolerance of an industrially manufactured balance wheel with four screws made of 1.4305 steel is typically ± 120 seconds per day, resulting in a total required adjustment range or rate tolerance of 240 seconds per day. In comparison, the aforementioned adjustment range of ± 150 seconds per day, which is most commonly used in practice, provides an adjustment reserve of ± 30 seconds per day. The required adjustment range or manufacturer-guaranteed rate tolerance of an industrially manufactured balance wheel with four screws made of grade 5 titanium is ± 75 seconds per day, resulting in a total required adjustment range or rate tolerance of 150 seconds per day. In comparison, the aforementioned adjustment range of ± 120 seconds per day provides an adjustment reserve of ± 45 seconds per day.

[0039] In detail, this can also be represented as follows: Adjustment effect by 1 turn of 360° per pair of screws made of 1.4305 steel: ± 41 sec. / day; with two pairs of screws (4 screws) and assuming a maximum of 2.5 possible turns per screw, this explains the aforementioned total adjustment range of ± 205 sec. / day for a balance wheel equipped with 4 screws made of 1.4305 steel. Adjustment effect by 1 turn of 360° per pair of screws made of grade 5 titanium: ± 24 sec. / day; with two pairs of screws (4 screws) and assuming a maximum of 2.5 possible turns per screw, this explains the aforementioned total adjustment range of ± 120 sec. / day for a balance wheel equipped with 4 screws made of grade 5 titanium.

[0040] When using approximately 35 classes for the balance wheel and the balance spring in the case of using screws made of Ti grade 5, instead of approximately 20 classes in the case of using screws made of 1.4305 steel according to the prior art, the class width is indeed narrower, namely approximately ± 46 sec. / day instead of the previously known class width of ± 79 sec. / day with 20 classes, but this makes it possible, due to the higher number of classes, namely approximately 30 to 40 classes, to cover approximately the same total class pairing range (35 x ± 46 sec. / day = ± 1,610 sec. / day; 20 x ± 79 sec. / day = ± 1,580 sec. / day).

[0041] Preferably, the entire assembly of inertia-adjusting elements 6 of the balance wheel according to the invention therefore consists of four screws arranged radially and offset by 90° on the rim 1, the total adjustment effect of which is less than ± 140 sec. / day, preferably less than ± 125 sec. / day. Their weight and geometry, including the thread pitch, are also selected such that a rotation of a screw by a maximum of 45°, preferably a maximum of 30°, causes a change in the rate of the movement of less than 1 sec. / day.

[0042] For the inertia adjustment elements or screws according to the invention, titanium refined by thermal ceramicization, e.g., according to patents US 9,382,607, US 9,303,306, US 9,382,606, or US 8,262,814, which is known to those skilled in the art as Ceratanium, can also be used. Ceratanium consists of a titanium alloy whose surface is transformed into a ceramic layer by a specific heat treatment. This is a naturally occurring diffusion layer and not a conventional coating. Therefore, Ceratanium is particularly resistant and scratch-resistant. It is about one-third lighter than steel and very biocompatible. The composition of Ceratanium is 51% titanium and 49% zirconium dioxide (by mass). Inertia adjustment elements or screws produced in this way had a volume mass of 5.3 g / cm³.It should also be noted that the ceramic layer thickness for watch components used for decoration is typically around 10 µm. For movement components that are not subject to wear, the layer can be thinner, in particular around 1 µm to 2 µm.

[0043] A balance wheel according to the invention allows for extremely simple handling and elegantly implements a device for adjusting the moment of inertia of the balance wheel.

[0044] It is also clear from the foregoing that the present invention is directed in particular to a regulating organ and to a clockwork which has a balance wheel according to the invention, as well as to a clock with a corresponding clockwork.

[0045] Furthermore, the detailed description of the balance wheel according to the invention above illustrates that the present invention allows its function to be optimized in an optimal manner through simple design features, without the need for structural changes to the balance wheel rim itself. Therefore, a balance wheel according to the invention also has the advantage of being usable with previously known components. However, the main advantages of the invention are that a balance wheel according to the invention, with only light inertia adjustment elements of the type described above, allows for fine adjustment of the moment of inertia of the balance wheel. This fine adjustment is sufficient due to the improved control of manufacturing tolerances in modern watch component manufacturing processes and results in only minor deviations in the timekeeping of the movement in the event of incorrect adjustments. List of reference symbols

[0046] Nr. element 1 Ripe 2a, 2b spokes 3 coil spring 4 Axis of vibration 5 indentation 6 screw 7 slot

Claims

1. Balance wheel for integration into a regulating organ of a clockwork, comprising a rim (1), spokes (2a, 2b) and an oscillation axis (4), wherein the rim (1) is connected to the oscillation axis (4) of the balance wheel via the spokes (2a, 2b) and is made of at least one first material, wherein the balance wheel comprises a plurality of adjustable inertia adjustment elements (6), characterized by the fact that the entirety of the inertia adjustment elements (6) made of a second material whose volume mass is less than 6 g / cm³ 3 is, is manufactured.

2. Unsprung according to the preceding claim 1, characterized by the fact that the said inertia adjusting elements (6) are screws or weights.

3. Balance wheel according to one of the preceding claims 1 to 2, characterized by the fact that the said inertia adjustment elements (6) are adjustable and mounted on said rim (1).

4. Balance wheel according to any one of the preceding claims 1 to 3, characterized by the fact thatthe volume mass of the aforementioned first material is between 6 g / cm³ 3 and 22 g / cm² 3 , especially between 6 g / cm³ 3 and 9 g / cm² 3 , amounts.

5. Balance wheel according to any one of the preceding claims 1 to 4, characterized by the fact that the aforementioned first material is selected from among the copper alloys, in particular brass or other copper-zinc alloys (Cu-Zn) and copper-bryllium (Cu-Be).

6. Balance wheel according to any one of the preceding claims 1 to 4, characterized by the fact that the aforementioned first material among the gold alloys, in particular the 9ct, 14ct and 18ct gold alloys, has been selected.

7. Balance wheel according to any one of the preceding claims 1 to 6, characterized by the fact that the volume mass of the second material is between 0.5 g / cm³ 3 and 6 g / cm² 3 , especially between 3 g / cm³ 3 and 5.5 g / cm³ 3 , amounts.

8. Balance wheel according to any one of the preceding claims 1 to 7, characterized by the fact thatthe said second material is a light metal or a light metal alloy, wherein the said second material is preferably selected from among the titanium alloys, the aluminum alloys, the magnesium alloys and the magnesium-lithium alloys.

9. Balance wheel according to the preceding claim 8, characterized by the fact that the said second material is ceramically finished, preferably by means of a ceramic surface coating of a thickness of less than 10 µm, in particular a thickness of 1 µm to 2 µm, preferably in the form of a coating of Ceratanium.

10. Balance wheel according to any one of the preceding claims 1 to 7, characterized by the fact that the said second material is a ceramic material, wherein the said second material is preferably selected from the group of materials containing silicon nitride, aluminum oxide, zirconium oxide and mixtures of aluminum oxide and zirconium oxide.

11. Balance wheel according to any one of the preceding claims 1 to 10, characterized by the fact that the entirety of the inertia adjustment elements (6) consists of four screws (6) which are arranged radially and each offset by 90° on the rim (1) and whose total adjustment effect is less than ± 140 sec. / day, preferably less than ± 125 sec. / day.

12. Balance wheel according to any one of the preceding claims 1 to 11, characterized by the fact that the entirety of the inertia adjustment elements (6) consists of screws whose weight and geometry, including the thread pitch, are selected such that a rotation of a screw by no more than 45°, preferably by no more than 30°, causes a change in the rate of the regulating organ of the clockwork of less than 1 sec. / day.

13. Regulating organ of a clockwork mechanism comprising a balance wheel according to any one of the preceding claims 1 to 12.

14. Clockwork mechanism comprising a balance wheel according to any one of the preceding claims 1 to 12 or a regulating organ according to the preceding claim 13.

15. A method for manufacturing a regulating element of a clock movement according to the preceding claim 13, the method comprising the steps of: - providing a series of balance wheels according to any one of the preceding claims 1 to 12, - providing a series of balance springs (3) suitable for forming a regulating element of a clock movement with these balance wheels, - measuring the moments of inertia of the balance wheels in said series of balance wheels and the stiffness of the balance springs (3) in said series of balance springs before their installation in a clock movement, - sorting and classifying the balance wheels in said series of balance wheels and the balance springs (3) in said series of balance springs according to their deviation from corresponding target values ​​into 30 to 40 balance wheel and balance spring classes, in particular into 35 balance wheel and balance spring classes, - pairing a balance wheel and a balance spring (3), each selected from corresponding balance wheel and balance spring classes.- Assembly of the paired balance wheel and spiral spring (3) to form a regulating organ of a clockwork.

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