EP1319997B1 - Constant force device - Google Patents

Abstract

Constant force device for precise working regulation of mechanical clocks by means of a balanced force transfer from the anchor wheel to the clock regulation organ. Said constant force device is integrated in the tourbillon mechanism. The constant force device works by balancing the decreasing force available from the drive spring (10). As a result a constant torque is applied to the clock regulation organ.

Description

The present invention relates to a constant force device for precise gear regulation of mechanical movements by means of a uniform force transmission from the escape wheel on the Regulierorgan the clock, said device is integrated into a tourbillon mechanism.

Generally Konstantkraftvorrichtungen known for a long time and are usually realized by a possessing at any time a certain bias auxiliary spring, which replaces the variable by the decaying tension of the tension spring drive the gear train clock and is periodically tightened by a certain, constant quantity. During their voltage reduction to maintain the vibration of Regulierorgans the clock, the transmitted force can be regarded as far more constant than the sole drive of Regulierorgans only on the mainspring.

The article "Les remontoirs d'égalité et les forces constantes dans la montre", written by Messrs. Y. Droz and J. Flores, deals with a watch with a constant force device of the type described above. In this case, the escape wheel is controlled by a first anchor and periodically released, which is generally the case with armature inhibitions. At the same time, the escape wheel is connected via a drive with a so-called constant wheel engaged and also controls a Reuleauxnocken a second anchor, which in turn is in engagement with a stop wheel. This stop wheel is concentric with the named constant wheel, which gives an approximately constant torque to the Regulierorgan, arranged, between these wheels, a biased coil spring is placed, which is subject by mutual rotation of these wheels of said periodic restraint. This can reduce to maintain the vibration of Regulierorgans controlled by the first anchor via the escape wheel and the drive way and rebuild at a time determined by the second anchor. The concentric arrangement of the stop wheel relative to the approximately constant torque transmitting wheel, however, leads to difficulties both constructive and functional nature.

The patent CH 120028 also sets forth such a constant force device, wherein the prestressed auxiliary spring between the stop wheel and the concentric arranged to this escape wheel. In this case, the escape wheel gives an approximately constant torque to the regulator. The transmission of an approximately constant torque is based on the same principle as the above embodiment despite different design of the device and a different arrangement of the associated anchor substantially. While conventional constant-force devices of this kind certainly provide improvements, such as an inhibition no longer influenced by the inertia of the gear train, the possibility of having the gear train fully subdued with appropriate design and, in particular, the transmission of a relatively constant torque, are nevertheless possible various disadvantages present. First, these conventional Konstantkraftvorrichtungen have the disadvantage that the transmitted torque is only approximately, but not completely constant, in so far as the voltage of the auxiliary spring decreases, without that would be corrected in these devices to this effect. The conventional use of the periodically tensioned auxiliary spring therefore brings an improved, but not optimal gear regulation of the gear train. Furthermore, the concentric arrangement of the stop wheel to the constant torque transmitting wheel causes various difficulties. A non-concentric arrangement would allow the free choice of both the relative position of these wheels and, in the case of integration of the constant force device into a tourbillon mechanism, the position of the stop wheel about a so-called fixed second wheel, thereby also engaging the stop wheel with a second wheel of different diameter stand could. In addition, this simplifies the construction of the device in the sense that the wheels in question need not be placed on an axle. Finally, the isolated use of a constant force device is disadvantageous in that a combination with other precision control devices such as a tourbillon mechanism allows a significant improvement in the effect.

The object of the present invention is to overcome the aforesaid difficulties and in particular the transmission of an actually constant torque to the regulating member of the watch and the consideration of non-concentric placement of the stop wheel relative to the constant torque transmitting wheel and integration into one Tourbillon mechanism resulting advantages.

The invention has a constant force device as an object, which is characterized by the enumerated in claim 1 license plate.

Further advantages will become apparent from the features formulated in the dependent claims and the description below with reference to the drawings in detail.

The accompanying drawings exemplify an embodiment of a constant force device according to the present invention.

The FIG. 1 is a top view of a tourbillon mechanism equipped with a constant force device according to the invention.

The FIG. 2 shows the tourbillon mechanism including the constant force device in section along the line A - A according to the FIG. 1 ,

The FIG. 3 For better understanding, the essential components of the device without the tourbillon cage as in FIG. 1 in a plan view.

The FIG. 4 Fig. 10 is a plan view of the main component of the constant force device.

The FIG. 5 is a section of the constant force device along the line A - A according to the FIG. 4 to illustrate in detail the integrated force compensation mechanism.

The FIG. 6 schematically illustrates the operation of the force balance mechanism.

In the following, this exemplifying embodiment of the device will be explained in detail with reference to the above-mentioned figures.

In the in the FIG. 1 The tourbillon mechanism illustrated incorporates a constant force device according to the present invention. The tourbillon mechanism has a tourbillon cage 1, in the center of which a balance 2 is rotatably mounted, a coil spring 3, a drive wheel 13 and a fixed second wheel 14, and possibly an unillustrated, concentrically arranged second fixed second wheel of different numbers or diameters , on.

The fixed second wheel 14, or in the presence of which the second fixed second wheel, is engaged with a Stopradtrieb 12 a, which is fixedly connected to a stop wheel 12 and in Tourbillonkäfig 1 is not centric, rotatably mounted. This stop wheel 12 has in the embodiment shown here two teeth cooperating with the anchor pallets 11 a and 11 b of a second armature 11 of the constant force device, which is pivotally mounted in the illustrated example in the axis of the tourbillon mechanism. Said anchor 11 is controlled by means of a fork-shaped, the anchor pallets 11 a and 11 b opposing portion 11 c of this armature 11 by a Reuleauxnocken 5, wherein the Reuleauxnocken 5 the shape of an equilateral triangle whose three sides form circular sections instead of lines possesses. These three sides of the Reuleaux cam 5 cooperate in a conventional manner with the fork-shaped part 11c of the armature 11 to control its pivotal movements.

How out Figure 2 or off Figure 3 it can be seen, the Reuleauxnocken 5 is part of another complex of Konstantkraftvorrichtung, which in turn is not centrally mounted in Tourbillonkäfig 1 and in particular not concentric with the stop wheel 12. The axis of this in the FIGS. 4 to 6 as a plan view, section and shown in its operation complex is formed by the escape wheel 9, which is rotatably embedded in Tourbillonkäfig 1 and at which in the upper portion of the Reuleauxnocken 5 and below an escape wheel 6 are attached. This escape wheel 6 has the teeth formed in the usual way and thus allows the movement of the escape wheel 6 by means of a seated on the tourbillon cage 1 and controlled by the balance 2 first armature 4, the two with the teeth of the escape wheel alternately engaged standing anchor pallets has to block or release.

In the lower portion of the escape wheel shaft 9, a tension ring drive 8 is mounted, rotatable about the same, to which a tension ring 7 is attached. The tension ring drive 8 is supported by a bushing 26 and is analogous to the stop wheel 12a engaged with the fixed second gear 14, which can provide the possibilities for the relative position of these two elements when integrating a constant force device according to the present invention in a tourbillon mechanism.

Between the escape wheel 6 and the tension ring 7 is, as in particular from Figure 5 can be seen, mounted a coil spring 10 of the constant force device, wherein this is realized by means of a special force compensation mechanism. This force compensation mechanism initially has a force compensation eccentric 20 fastened on the side of the tension ring 7 opposite the escape wheel 6, the axis of which is displaced parallel to the axis of the escape wheel shaft 9 and the axis of rotation of the tension ring drive 8 which is identical to the latter. To this in various forms realizable, in particular not necessarily circular Eccentric 20 is a force-compensating disc 21 rotatably mounted, which in the present example has two opposite arms as points of attack (21a, 21b), but of course quite different, functionally identical shape can take. Above this disc is a fixed to the escapement 9, fixed coil spring 23, to which a free end of the coil spring 10 is attached. The other free end is fixed to a mobile spiral spring roller 22 which is rotatably mounted around the fixed spiral spring roller 23 and thus about the axis of the escape wheel shaft 9. Both the fixed spiral spring roller 23 and the mobile spiral spring roller 22 have in a, at the outer edge of the respective spiral spring roller and here at the same distance from the axis of the escape wheel shaft 9 hole downwardly, in the direction of the force compensation disc 21 exiting pin 24 and 25 , These two pins 24 and 25 are placed so that they are located on the same side of a located in the line of the two arms of the force compensation disc 21, on this latter vertical plane and can cooperate with these arms 21 a and 21 b.

In addition to the conceptual design, the mode of operation of a device designed in this way can also be illustrated by way of example with reference to the illustrated embodiment. The drive of the balance 2 takes place by the prestressed coil spring 10, the provision of the balance by the second coil spring 3. After each - determined by the number of teeth of the escape wheel and quite different - fifth Halbschwingung the balance 2, the stop wheel 12 and the cage 1 of Tourbillon mechanism on the Reuleauxnocken 5 and the second armature 11 released. The stop wheel 12 then rotates by a certain given by its number of teeth angle, in the present case by 90 °, and is stopped by an anchor pallet of the armature 11 again. Insofar as the stop wheel and the stopwheel drive 12a are seated on the tourbillon cage and the latter is in engagement with the fixed second wheel 14 or the second fixed second wheel, this rotation of the stop wheel 12 simultaneously causes rotation of the tourbillon cage 1, which in turn causes rotation of the tourbillon cage Stress ring drive 8, which also sits on the tourbillon cage and is in engagement with the fixed second wheel 14. The thus occurring rotation of the tension ring 7 has the renewed tension of the coil spring 10 result, on the other hand, the escape wheel 6 is blocked by the first armature 4. By repeating this procedure after every fifth half vibration of the balance 2, the coil spring 10 is periodically tensioned by the same quantity.

erfassen, welche somit die Berechnung des notwendigen Hebelarmverhältnisses oder der Eigenschaften der Spiralfeder 10 und damit die entsprechende Gestaltung des Kraftausgleichsmechanismus erlaubt.The stored by the voltage of this coil spring 10 energy can be passed to maintain the vibration of the balance 2 in the form of a torque, the voltage until the re-tensioning of the spring in only slightly, but appreciably decreases for the desired precision manner. The energy transfer therefore takes place by means of the special force compensation mechanism, which ensures the transmission of an actually constant torque. The attached at one end to the mobile coil spring 22, tensioned coil spring 10 exerts a force on the located in this coil spring roller pin 22 25, which transmits this force via one of said arms of the force-compensating pulley 21 as a torque to this. The other arm of the force-balancing pulley 21 acts on the pin 25 fixed in the fixed spiral spring roller 23 and thus transmits the torque to this fixed spiral spring roller 23 and the escape wheel 6. Insofern, as from Figure 6 it can be seen that the axes of rotation of the escape wheel shaft 9 and the force compensation disc 20 mounted force compensation disc 21 are displaced parallel to each other, the lever arms L1 and L2 are variable for the torque present on the two arms of the force compensation disc 21. An appropriate choice of the length of these lever arms in the various positions of the force compensation disc 21 as a function of the forces applied there F1 and F2 allows a despite the voltage reduction of the coil spring 10 during standstill of the entire gear train from the barrel to the stop wheel 12 actually constant torque on the escape wheel 6 to achieve. In the in Figure 6 In concrete terms, this means that the length L1 of the first lever arm in position 1, so the point of application of the pin 25 on one arm of the force compensation disc 21 in this position, upon rotation to the position 2 to the length L1 'extended while the length L2 of the second lever arm, so the point of the pin 24 on the other arm of the force compensation disc 21, shortened to L2 '. Thereby, the ratio L1 '/ L2' is increased, whereby the reduction of the force F1 in the position 1 to the force F1 'due to the reducing tension of the coil spring 10 is compensated. It is thus achieved that the force F2 remains constant during the rotation, so that equally the torque transmitted to the escape wheel 6 is constant. Mathematically, this condition can be expressed by means of the equation $$\mathrm{F}\mathrm{1}\mathrm{/}\mathrm{F}\mathrm{1}\mathrm{\text{'}}\mathrm{=}\left(\mathrm{L}\mathrm{1}\mathrm{\text{'}}\mathrm{*}\mathrm{L}\mathrm{2}\right)\mathrm{/}\left(\mathrm{L}\mathrm{1}\mathrm{*}\mathrm{L}\mathrm{2}\mathrm{\text{'}}\right)$$

capture, which thus allows the calculation of the necessary Hebelarmverhältnisses or the properties of the coil spring 10 and thus the corresponding design of the force balance mechanism.

At each half cycle of the balance 2, the escape wheel 6 is released from the first armature 4 and rotates under the influence of the tensioned coil spring 10 by an angle ε about its axis, as well as the fixed coil spring 23 and the force-balancing pulley 21, while the tension ring 7 and Stop wheel 12 are blocked.

With every fifth vibration, the stop wheel and the tourbillon cage are also released. As described above, thereby the tension ring 7 rotates by a predetermined angle, in the present example by 60 °, and returns to its initial position relative to the escape wheel 6, resulting in the re-tensioning of the coil spring 10 by a certain quantity. The entire process described repeats periodically and thus allows constantly to transmit a constant torque from the escape wheel 6 to the regulating member of the watch, the balance 2.

The advantages of such a device are evident. First of all, this device provides as described by means of the special force compensation mechanism a corrected to the decreasing voltage of the driving coil spring, constant torque to the regulating member of the clock, in contrast to the conventional constant-force devices. The introduced force compensation mechanism consists of only three new parts and therefore does not constitute a significant complication of the device, especially in so far as little space is needed and these parts can be easily arranged around the escape wheel shaft. In addition, the system can be adjusted so that the torque remains constant, even if the bias of the coil spring deviates within a certain range.

As mentioned, in addition to the non-concentric arrangement of the stop wheel relative to the constant torque transmitting wheel, in this case to the escape wheel 6, offers various advantages. In the case of integration of the constant force device in a tourbillon mechanism, the position of the stop wheel can be freely selected by the fixed second wheel, it can also be engaged by its drive with a second fixed second wheel of different diameter. The diameter and the number of teeth of the stop wheel and the number of teeth of the stop wheel can be chosen freely within a certain frame, whereby the engagement of the anchor pallets are optimized and the rotational speed of the stop wheel may be different from that of the escape wheel. It also structural advantages, such as that the access to the escapement and Konstantkraftvorrichtung is simplified because the escape wheel and the stop wheel are not placed on top of each other, or that by this placement and reducing the rotational speed of the stop wheel - in the case of integration of the Constant force device in a tourbillon mechanism - the moment of inertia of the tourbillon cage can be optimized. Furthermore, a fine regulation system can be mounted on the tension ring. Since the tension ring in the concentricity requires no special tolerance, a running fit between the tension ring and the escape wheel shaft can be selected, so that as in the embodiment described in detail the escape wheel firmly mounted on the escape wheel shaft. This leads to a minimization of the running tolerance of the escape wheel, which thus corresponds to the tolerance of a standard escapement without constant force device. In general, the fact that the escape wheel and the stop wheel do not have the same axis simplifies the design, manufacture and control of the watch.

In particular, the possibility of integrating such a constant force device in a tourbillon mechanism, which is included in the described embodiment, is also of great interest insofar as the complementary properties of these two systems for precise regulation of the movement can be effectively combined. Thus, the inhibition is no longer influenced by the inertia of the gear train. With appropriate design so that the stop wheel is released once per second, the mechanism can display full seconds. The usual in a tourbillon mechanism when stopping the tourbillon cage, which adversely affect the dynamics are greatly reduced by the tensioning of the coil spring and the introduction of the force balance mechanism. The tourbillon cage is thus slowed down instead of stopping abruptly.

Finally, the arrangement of the axis of rotation of the second armature in the center of the tourbillon cage is advantageous. This avoids influencing the moment of inertia of the tourbillon cage by the anchor as opposed to otherwise placing it, and optimizes the dynamics of the system.

The exemplified embodiment is in no way limiting insofar as the additional features shown there, such as the non-concentric position of the stop wheel relative to the constant torque transmitting wheel, the placement of the second armature in the center of the bogie, or integration into a tourbillon mechanism, are omitted can or as well as the detail design of the Force compensation mechanism can be subject to functionally identical changes.

Claims (6)

1. Constant force device, which has a stop wheel (12) which is fastened to a stop wheel drive (12a), an escapement wheel (6), which is fastened to an escapement wheel shaft (9), a tensioning ring (7), which is fastened to a tensioning ring drive (8), and a cam (5), which is fastened to the escapement wheel shaft (9), wherein the movement of the escapement wheel (6) is blocked or released by two escapement palettes of a first escapement (4), and wherein the movement of the stop wheel (12) is blocked or released by two escapement palettes (11a, 11b) of a second escapement (11), which is controlled by means of a fork-shaped part of this escapement (11), which part engages with the cam (5), wherein it has a force compensation mechanism which ensures the transmission of a constant torque to the regulating means of a clock while compensating the decreasing tension of a spring (10) which delivers the drive energy, wherein this force compensation mechanism is situated between the escapement wheel (6) and the tensioning ring (7) which is mounted rotatably around the escapement wheel shaft (9) by means of the tensioning ring drive (8), characterised in that a force compensation eccentric (20) is fastened to the tensioning ring drive (8) on the side of the tensioning ring (7) which is opposite the escapement wheel (6), which eccentric defines an axis of rotation which is displaced parallel to the axis of the escapement wheel shaft (9), and on which eccentric a force compensation disc (21), which has at least two engagement points (21a, 21b), is mounted in a rotatable manner.
2. Constant force device according to Claim 1, characterised in that the said spiral spring (10) of the constant force device is fastened at one end to a fixed spiral spring collet (23), which is fastened to the escapement wheel shaft (9) and has a pin (24) which protrudes in the direction of the force compensation disc (21), and is coupled at the other end to a mobile spiral spring collet (22) which is mounted such that it can rotate around the fixed spiral spring collet (23) and has a pin (25) which protrudes in the direction of the force compensation disc (21), wherein the two pins (24, 25) with the said engagement points (21a, 21b) of the force compensation disc (21) co-operate in such a manner that the lever arm lengths of the forces which are exerted at these engagement points with the aid of the pins (24, 25) present there change as a function of the position of the force compensation disc (21) which rotates about the force compensation eccentric (20) in such a manner that the reduction of the force which is exerted on the force compensation disc (21) by means of the pin (25) of the mobile spiral spring collet (22), which is brought about by the decreasing tension of the spiral spring (10), is compensated in such a manner that the torque which is transmitted through the force compensation disc (21) via the pin (24) of the fixed spiral spring collet (23) to the escapement wheel (6) is constant in all positions relative to the tensioning ring (7).
3. Constant force device according to one of the preceding claims, characterised in that the stop wheel (12) is arranged non-concentrically to the escapement wheel (6) which transmits the constant torque.
4. Tourbillon mechanism, which has a tourbillon cage (1), a balance wheel (2), and a fixed second wheel (14), characterised in that it has a constant force device according to one of the preceding claims.
5. Tourbillon mechanism according to the preceding claim, characterised in that the escapement wheel (6) is mounted rotatably to the edge of the tourbillon cage (1), and the tensioning ring drive (8) is in engagement with the fixed second wheel (14), that the stop wheel (12) is mounted rotatably on the edge of the tourbillon cage (1) non-concentrically to the escapement wheel (6), and the stop wheel drive (12a) is in engagement with the fixed second wheel (14) or a second fixed second wheel which is mounted concentrically to this, and that the balance wheel (2) controls the movements of the first escapement (4) of the constant force device.
6. Tourbillon mechanism according to Claim 4 or 5, characterised in that the axis of rotation of the second escapement (11) is arranged in the centre of the tourbillon cage (1).

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