EP2037335A2 - Anchor for a timepiece escapement - Google Patents

Abstract

The anchor (1) has two anchor arms (2) in each of which a pallet (3) is held. A fork (4) and a fork clamp are provided at its end, which acts on a balance wheel. The exit pallets carrying anchor arms and fork together with two fastening arms (7) are integrally manufactured. The fastening arms, which run in the same plane as the other anchor units, are elastically shaped with a certain length. An independent claim is included for a method for manufacturing an anchor.

Description

The present invention relates to an anchor for a watch escapement with escape wheel of a mechanical watch according to the preamble of claim 1.

The basic features of the function of a mechanical watch are today well known and well documented. The movements of mechanical watches generally draw their energy from a spring, usually a coil spring, the elevator spring or the so-called Barillet. This energy is delivered to a gear transmission, which in turn via pointer elements, for example, the information for the display of the hour reproduces, to the last element, the so-called inhibition. The latter has three functions, namely to count the number of oscillations of the balance, that is, to measure the time, to block the energy of the gear during the additional turn of the balance and to give the balance an impulse to maintain its oscillating motion. The so-called Swiss lever escapement, where each of the pallets held in the anchor alternatively provides a boost from the Escapement wheel gets to pass it on to the balance, which is the most widely used in the watch industry.

Like any mechanical system, the flow of force is subject to friction. The energy that has been collected in the elevator spring experiences losses in the transmission from the mainspring via the transmission to the last element, the balance. This has several disadvantages. To compensate for the energy losses, the elevator spring must be increased in order to obtain a sufficient service life of the clock and the drain reserve. In order to reduce the influence of the friction losses relatively, the vibration frequency or the inertia of the balance could be increased. The improvement in accuracy achieved in this way would have to be bought in turn with the enlargement of the balance or the mainspring, which is undesirable.

Part of the energy stored in the elevator spring is lost due to friction in the tooth meshing process and when turning the gear train into its bearing. Typically, each stage of the gear train has an efficiency of about 90% to 95%. The tooth engagement and profile of the teeth have been optimized as a result.

• ■ Übertragung der Energie des Hemmungsrades an die Paletten des Ankers;
• ■ Führung des Ankers durch seine Achse in den Lagersteinen;
• ■ Übertragung der Energie des Ankers an die Unruh und Reibungsverluste der Lagerung der Spindel der Unruh in einem entsprechenden Lagerstein.

Another part of the energy is lost at the inhibition, especially by sliding friction. Typically this is Efficiency of the latter about 40%. The losses at the inhibition can be separated in several parts:

• ■ transmission of the energy of the escape wheel to the pallets of the anchor;
• ■ Guide the anchor through its axis in the jewels;
• ■ Transfer of the energy of the armature to the balance and friction losses of the bearing of the spindle of the balance in a corresponding jewel.

In order to improve the efficiency of the inhibition, many solutions have been proposed in which adjustments have been made to achieve the most energy efficient way of transferring the escape wheel to the pallets of the anchor. This is how the documents reveal CH-A-570644 and CH-342897-A , the document CH-342 897 or even the WO-2007/003539 Solutions that refer to the optimized geometry of the pallet.

Other documents, like the DE-2050013-A and the CH-A-510 285 are aimed at improving the transfer of energy from the anchor to the balance.

The storage and leadership of the anchor or its axis in jewels (usually rubies) has been substantially improved since the first watches with anchor inhibitors. Natural rubies and later synthetic rubies have been used as a material to reduce friction and wear To reduce the journal of the axles. It has also reduced the diameter of the journals of the axis of the anchor and adapted. Also, lubricants were used on the journal and the lubricants were continually improved.

The lubricants, however, have the disadvantage of deteriorating over time, namely aging, oxidizing, cracking and rancidity. In addition, lubricants are susceptible to the absorption of dust and tend to harden. Lubricants are therefore hardly used for bearing journals of the anchor. Despite all precautions friction and play between the journals of the anchor axle and their jewels are still present with the well-known disadvantages. It is therefore the object of the present invention to provide an anchor that oscillates virtually free of play and friction-free movement whereby the efficiency of the inhibition is to be improved.

This object is achieved by an anchor of the type mentioned above with the features of claim 1. The invention also shows two methods for producing the inventive anchor according to claims 18 and 19.

Figur 1:

Eine Aufsicht auf eine erste Ausführungsform des erfindungsgemässen Ankers und

Figur 2:

denselben Anker in einer perspektivischen Ansicht.

Figur 3:

zeigt eine zweite Ausführungsform des erfindungsgemässen Ankers in der Aufsicht, wobei die Schwenkbewegung des Ankers beziehungsweise dessen Gabel beschränkt ist und

Figur 4:

zeigt wiederum diese zweite Ausführungsform in einer perspektivischen Darstellung.

Figur 5:

zeigt abermals in einer Aufsicht eine dritte Ausführungsform des erfindungsgemässen Ankers der so gestaltet ist, dass er gewisse parasitäre Bewegungen zu kompensieren vermag, und auch hier ist in der

Figur 6:

dieser Anker in perspektivischer Lage gezeigt. Eine nochmals andere, vierte Ausführungsform zeigt die

Figur 7:

in der diese vierte Ausführungsform des erfindungsgemässen Ankers in der Aufsicht und

Figur 8:

in perspektivischer Darstellung gezeigt ist. Die

Figuren 9 - 11:

zeigen einen herkömmlichen Anker in der Seitenansicht in der Aufsicht und in perspektivischer Darstellung.

Further advantageous embodiments of the subject invention will become apparent from the dependent claims and their meaning and effect are explained in the following description with reference to the accompanying drawings. It shows:

FIG. 1:

A plan view of a first embodiment of the inventive anchor and

FIG. 2:

the same anchor in a perspective view.

FIG. 3:

shows a second embodiment of the inventive anchor in the plan view, wherein the pivoting movement of the armature or the fork is limited and

FIG. 4:

again shows this second embodiment in a perspective view.

FIG. 5:

shows again in a plan view a third embodiment of the inventive anchor which is designed so that it is able to compensate for certain parasitic movements, and here is in the

FIG. 6:

this anchor shown in perspective. Yet another, fourth embodiment shows the

FIG. 7:

in this fourth embodiment of the inventive anchor in the plan view and

FIG. 8:

is shown in perspective view. The

Figures 9-11:

show a conventional anchor in the side view in plan view and in perspective.

For now, with respect to the FIGS. 9-11 a conventional anchor described. The anchor as a whole is denoted by A. The anchor has two anchor arms B, in each of whose ends a pallet C is held. In the middle between the two armature arms in the connecting region engages a fork D, which extends virtually perpendicular or at least on an angle bisector of the two armature arms. The fork D ends in tines E and the pivotal movement of the armature or the fork D is limited by two lateral anchor boundary pins F in the pivoting movement. This pivoting movement takes place about a bearing axis G with bilateral bearing journals H, which rest in bearing stones, not shown here. It goes without saying that these journals H store with a certain friction and thus with loss of energy in the jewels and it is also clear that these journals can not be stored without clearance in the jewels. As mentioned above, this leads to the corresponding energy losses and a gear inaccuracy.

In all of the following embodiments of the inventive armature is immediately apparent that this has in any of the embodiments shown here a concrete bearing axis. This also applies correspondingly in the first embodiment according to the Figures 1 and 2 to. Overall, the anchor according to the invention is always designated 1. Also, this anchor has like two anchor arms 2 like a conventional anchor. The pallets 3 are held at the end in the two anchor arms 2. These two armature arms 2 are integrally connected to each other and in the connection area, the fork 4 engages the armature. The fork 4 is practically perpendicular to the two armature arms 2, when they are stretched aligned with each other. If the two anchor arms 2 enclose an angle deviating from the angle 180 °, the fork 4 lies on the bisector of said angle. Terminally, the fork 4 forks 5 and the fork horn on. This part again corresponds to the conventional style. The region in which the fork 4 is connected to the two armature arms 2 is defined here as the connection region 6. In this connection region 6, two fastening arms 7 engage. These attachment arms 7 extend exactly straight in the simplest embodiment shown here. With respect to the central axis through the fork 4, the two attachment arms 7 extend mirror-symmetrically. Consequently, so forms the fork 4 and the center axis of the Angle bisector with respect to the angle, the two mounting arms 7 include each other.

Terminal at the two mounting arms 7 are fasteners 8, which are configured in the preferred embodiment here as an annular eyelets. Accordingly, the following is also spoken of eyelets 8, the expert will understand, of course, other fastener forms underneath. The choice of fasteners as eyelets is therefore preferred because they are both suitable to be connected by means of screws with a corresponding fixed part of the movement, for example, the movement board. But the eyelets 8 are also suitable for a soldered or welded connection as well as for an adhesive connection. For the latter types of connection but simple disc-shaped embodiments of the fasteners would be just as suitable.

Hierbei gilt, dass $$\mathrm{I}\mathrm{=}\mathrm{b}\mathrm{\times }{\mathrm{h}}^{\mathrm{3}}\mathrm{/}\mathrm{12.}$$

In dieser Formel gilt:

E =

E-Modul des Materials

b =

Breite des Befestigungsarmes

h =

Höhe des Befestigungsarmes

l =

Länge des Befestigungsarmes

I =

Flächenträgheitsmoment des Balkens

K =

Die Gesteifigkeit des Balkens.

Also in the inventive anchor, the force is introduced as in a conventional anchor from the escape wheel on the pallets, which are also often called exit pallets. The entire armature 1 is usually in one piece with the exception of the two output pallets of a plate-shaped material. It is preferable to choose a high modulus material. The force exerted by the escape wheel on the pallets 3 leads to a bending deformation the mounting arms 7. The width b of the mounting arms is kept as small as possible. The height h of the attachment arms 7 is a multiple of the width b of these arms. With regard to the flexural strength of the attachment arms, the following formula results: $$\mathrm{K}\mathrm{=}\mathrm{3}\mathrm{e}\mathrm{1}\mathrm{/}{\mathrm{I}}^{\mathrm{3}}$$

It is true that $$\mathrm{I}\mathrm{=}\mathrm{b}\mathrm{\times }{\mathrm{<figure-callout\; id="3"\; label="H"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">H</figure-callout>}}^{\mathrm{3}}\mathrm{/}\mathrm{12th}$$

In this formula:

E =

Modulus of elasticity of the material

b =

Width of the attachment arm

h =

Height of the attachment arm

l =

Length of the attachment arm

I =

Area moment of inertia of the beam

K =

The stiffness of the beam.

From this formula it can be seen that the smoothest possible embodiment of the inventive anchor is achieved by making the attachment arms as long as possible and as thin as possible in width. With regard to the height of the attachment arm is of course not free, since this must be sufficiently large so as not to obtain rotational degrees of freedom that are not in the plane of the anchor. If you would also choose the height of the mounting arm also very small, so the mounting arms would behave like threads and would be stiff only on train and pressure but otherwise very flexible in all bending directions. But this is not wanted but the freedom of movement should be limited to a bending movement of the mounting arms 7 within the extension plane in which the anchor is located.

However, the simplest embodiment of the inventive anchor described so far with two flexible mounting arms 7 still has a relative disadvantage. This anchor has a so-called parasitic motion. This is the unwanted, albeit small, erroneous movement of the rotation center, so called the virtual axis. The third embodiment of the subject invention, as shown in the FIGS. 5 and 6 is shown, also solves this problem. Ideally, the armature should rotate about a given virtual axis without offset movement of the center. This problem can be largely reduced, for example, by allowing the mounting arms 7, as in the FIGS. 5 and 6 represented, designed. Here, the fastening arms 7 are designed with two parallel elastic sections 70 and 71. These two sections 70 and 71 are hairpin-like. The two sections are parallel and arranged in opposite directions. The two elastic partial sections 70, 71 are connected to one another via a thickened connection point 72. The first elastic section 70 thus extends between the thickened connection point 72 and the connection region 6 of the armature 1 or to a thickened part of the Mounting arms 7 which is referred to here as the connecting part 73. The second elastic section 71 extends from the thickened connection point 72 to a thickened fastening arm part 74, on which the fastening element or fastening eye 8 is formed at the end.

The in the first described embodiment according to the Figures 1 and 2 As mentioned, the solution results in a slight shift of the center of the virtual axis of rotation. This shift is triggered by the deformation movement of the attachment arms 7. The attachment arms shorten their length somewhat when they are bent. The strength of this displacement depends both on the length of the attachment arms 7 and on the angular position, the deflection, of the armature. This parasitic movement is now largely compensated by the third embodiment of the subject invention according to FIGS FIGS. 5 and 6 , A further advantage of this embodiment is that twice the length of the movable part of the fastening arms 7 is achieved by the two elastic partial sections 70 and 71 practically with the same space requirement. Consequently, this solution not only compensates for the parasitic movements, but also reduces the stiffness of the attachment arms, so that the energy required for deformation is less.

There are also other embodiments for the reduction of parasitic movements known, which would also be suitable. For this purpose, for example, the solution according to the EP-1013949 Figure 4 directed. Other suggestions also go from the publication by WH Wittrick "The properties of crosslecture pivots and the influence of crosses" (The aeronautique, born 1951 ). Normally, and in particular with conventional armatures, their movement is limited by means of anchor-limiting pins. In a second preferred embodiment, as shown in the FIGS. 3 and 4 is shown, the fastening elements 8 are now designed such that they themselves form stops which limit the oszilierende rotational movement of the fork. For this purpose, the attachment lugs 8 movement limiting stops 9, which are designed in the form of bulges in the direction of the fork 4 out. Again, these attachment limit stops 9 are monolithically designed as part of the fasteners or eyelets 8 in turn. Thus, it is unnecessary in the clockwork itself provide anchor limit pins.

Finally, let me also to the 4th embodiment as in the FIGS. 7 and 8 is shown referenced. The embodiments described so far also have a small residual rigidity in the direction of movement.

Although part of the momentum given by the armature to the balance is reimbursed by it, part of the work is spent on the movement of the armature itself and on the elastic deformation work of its attachment arms. This work is significantly lower than the energy delivered by the escapement wheel. In order to reduce the spring stiffness of the armature, it is proposed in this embodiment, again monolithically integrally form a zugelastisches spring element 10 at anchor again. At the free end of the elastic spring element 10, a mounting plate 11 is attached. Through this slot 12, the mounting plate 11 can be adjustably screwed by means of a screw on the board of the clockwork. As a result, the bias of the zugelastischen spring element 10 can be adjusted. The elastic spring element 10 lies in the same plane as the fastening arms 7 and the remaining parts of the armature 1 according to the invention.
Of course, the fastening arms 7 must be fastened with their fastening element 8 either on the same board of the movement or at least on another fixed part of the movement, which lies in the same plane. Also, the zugelastische spring element 10 has a much smaller width b in relation to height h. The zugelastische spring element 10 may in principle have any shape that deviates from a straight line. Thus, the zugelastische spring element 10 could be as simple, arcuate arched arm be designed or as shown here, as in the plane meandering route.

While in the embodiments described above, the two fastening arms 7 are arranged mirror-symmetrically with respect to the central longitudinal axis of the fork 4, a different solution is shown here. The elastic attachment arms 7 are in turn as elongated elements between the connecting portion 6 and the terminal fasteners 8, which in turn are configured here as eyelets, extending. These two fastening arms 7 are now both arranged on the same side of the fork 4 between these and an armature arm 2. The zugelastische spring element 10 is now placed so that the connecting line between the center of the elongated hole 12 and the point of attachment of the zugelastischen spring element 10 at the connecting portion 6, the bisecting line between the two mounting arms 7. The virtual axis of rotation is always at the intersection of the extensions of the two mounting arms 7. While in the examples described above, where the mounting arms 7 are arranged mirror-symmetrically with respect to the fork 4, this virtual axis of rotation can also lie outside the connection area 6, it is in the Embodiment according to the FIGS. 7 and 8 preferably such that the virtual axis of rotation lies in the center of the connecting region 6. In other words, the place of virtual axis of rotation can thus be determined virtually free by the choice of the arrangement of the mounting arms 7.

Thanks to the use of an elastic spring element 10, as described above, a preload force is now exerted on the attachment arms 7. Thanks to this biasing force, the angular stiffness of the armature 1 can be changed or set thanks to the slot 12. This bias can be increased so far that, in principle, the anchor gets into an unstable position. The anchor is then operated in the so-called bistable buckling mode. In other words, with little force, the armature jumps about the virtual axis of rotation pivoting from one end position to the other end position.

In the FIG. 7 is contrary to FIG. 8 also shown the possibility that the pallets 3 also monolithic one piece and thus made of the same material as the anchor 1 in one operation. Since one chooses according to the invention and preferably a manufacturing method for the production of the inventive anchor, in which the boundary edges of the armature are extremely regularly finished with a very low roughness, friction losses are thus reduced. In particular, two methods are suitable for the production. One method is called a DRIE method. DRIE stands for Deep Reactive Ion Etching. This procedure was by the company Bosch develops and in this regard, for example, on the documents DE-3927163 or DE-4420962-A directed. By means of this method, fastening arms 7 can be produced with a very small width. Typically, the attachment arms 7 are made with a width of 15-50 microns. The geometry of an inventive anchor produced in this way has an extreme accuracy, with deviations that are usually less than one micrometer.

Among other things, silicon in the form of wafers may be considered as the material of manufacture for this process. This material is particularly suitable for the production of the anchor. In fact, this material has ideal properties for this application. It has a high mechanical strength and a very low plastic deformability, so that the areas with large thickness in the loading direction have virtually no deformation. This leads to extremely low losses. Material fatigue practically does not occur as long as the applied stresses at the alternating stresses are kept below the elastic breaking point. Finally, silicon has a very low coefficient of friction. The only problem is that the parts etched by the DRIE method have very sharp edges. For the watchmaker who works with the tweezers, it is thus possible for the watchmaker to produce very high pressures locally on the sharp edges. This can lead to the destruction of the anchor.

To remedy this disadvantage, one can change the surface of the workpiece by either oxidizing or nitriding the surface. Here, material is deposited around the edges or material is removed, so that the edges undergo certain curves. The silicon oxide and the silicon nitride also have tribological advantages in which in turn the coefficient of friction is positively influenced.

It is also possible to apply a hard layer to the silicon surface by growing a synthetic diamond or sapphire thereon. These are also known coating methods.

Although silicon is the preferred material for the anchor, it can also be made of quartz, pyrex glass, sapphire or diamond. All these materials can be produced synthetically, are accordingly hard and abrasion resistant. In addition, these materials can be at least partially processed by the DRIE method. Another preferred manufacturing method is known from the so-called LIGA technology. With regard to the LIGA process, reference is made, for example, to the European patents EP-0183910A or the EP-1431844-A as well as on the U.S. Patent 6458263-B directed. In particular, nickel or nickel phosphorus compounds are used for the LIGA process. Also by means of this method can be an inventive anchor with the required dimensions and manufacture accuracy having the desired physical properties. The LIGA process is a lithographic-galvanic etching process.

In addition to the two preferred production methods described here, of course, other suitable methods come into question with the respectively suitable materials. Merely for the sake of completeness, the possibility of wire-electric erosion may be mentioned here as an example, in which case the armature is formed from a corresponding steel or the production of metallic glasses is mentioned by the so-called micro-structuring method (micro-molding).

LIST OF REFERENCE NUMBERS

A

conventional anchor

B

anchor arms

C

pallets

D

fork

e

prong

F

Anchor limit pins

G

bearing axle

H

pivot

1

anchor according to the invention

2

anchor arms

3

palette

4

fork

5

forks

6

connecting area

7

mounting arms

8th

Fastener, eyelets

9

Motion limiting stops

10

elastic spring element

11

mounting plate

12

Long hole

70

first elastic sections

71

second elastic sections

72

compacted junction

73

connecting part

74

bracket portion

Claims (20)

Anchor (1) for a clock escapement of a mechanical watch with escapement wheel, comprising two armature arms (2) in each of which a pallet (3) is held and a fork (4) at the end a fork horn is present which acts on the balance, characterized in that the armature arms (2) and the fork (4) carrying the output pallets are made in one piece together with two fastening arms (7), the fastening arms (7) extending in the same plane as the other armature parts having at least one partial stretch so that they are elastically flexible are designed such that the anchor in the plane about a virtual axis under the action of the escape wheel on the energy transmitted to them can vibrate, the central axes of the two attachment arms (7) intersect in the virtual axis. Anchor according to claim 1, characterized in that the virtual axis in the connecting region (6) of anchor arms (2) and anchoring fork (4). Anchor according to claim 1, characterized in that the virtual axis is outside the armature (1). Anchor according to claim 1, characterized in that the two fastening arms (7) are arranged symmetrically to the anchor fork (4), so that the anchor fork is located on the bisector of the enclosed by the two mounting arms (7) or their two elastic sections angle. Anchor according to claim 1, characterized in that at the free ends of the two fastening arms (7) fastening element (8) are integrally formed. Anchor according to claim 5, characterized in that the two attachment arms (7) extend from the attachment element (8) to the region of the connection (6) of the anchor fork (4) and anchor arms (2) and are elastic over the entire length are. Anchor according to claim 5, characterized in that the fastening elements (8) are arranged so that form their peripheral movement limit stops which define a maximum deflection of the armature fork. Anchor according to claim 5, characterized in that the fastening elements (8) have a shape with the anchor fork directed toward formations that form Bewegungsbegrenzungsanschläge (9), which define a maximum deflection of the anchor fork (4). Anchor according to claim 1, characterized in that both fastening arms (7) lie on the same side between the anchor fork and an anchor arm (2). Anchor according to claim 9, characterized in that on the bisector between the two mounting arms (7) a zugelastisches spring element (10) is integrally formed, which is provided with a mounting plate (11) for attachment to the torsional stiffness of the armature (1) Reduce. Anchor according to claim 10, characterized in that the mounting plate (11) has a slot (12) for fixing the spring element (10) with adjustable bias to adjust the torsional stiffness of the armature (1). Anchor according to claim 1, characterized in that the fastening arms (7) each have two elastic partial sections (70, 71) which are arranged parallel in opposite directions. Anchor according to claim 12, characterized in that the two partial sections (70, 71) are designed hairpin-like and over a thickened connection point (72), the two partial sections (70, 71) are interconnected. Anchor according to claim 1, characterized in that the fastening arms (7) are fixed to an immovable part of the movement. Anchor according to claims 5 and 14, characterized in that the fastening elements (8) are fastened by means of screws on the movement. Anchor according to claims 5 and 14, characterized in that the fastening elements (8) are permanently attached by welding, soldering or gluing the movement. Anchor according to claim 12, characterized in that it is monolithically made of brittle material, in particular from the selection of - synthetic gemstone, especially diamond - Synthetic semi-precious stone - Silicon or silicon compound Anchor according to claim 17, characterized in that the armature is made of silicon wafer whose surface is nitrided or oxidized. A method for producing an anchor according to claim 1, characterized in that this is made of silicon after the DRIE method (Deep Reactive Ion Etching), in particular according to the cryo-DRIE method is produced. Method for producing an anchor, characterized in that it is produced by the lithographic galvanic molding method (LIGA method).

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