Anchor with curved pallet stone for Swiss lever escapement

Abstract

To provide an anchor for a Swiss lever escapement, a Swiss lever escapement, and a watch movement that enable improved performance of the escapement while maintaining a sufficient safety distance between the pallet stone on the anchor and the teeth of the escapement wheel during the operation of the escapement. [Solution] An escapement 21 for a watch escapement mechanism 50 with a Swiss lever, the escapement 21 comprising a fork 22 designed to engage with an ellipse 23 on a balance wheel 35, and an inlet arm 11 and an outlet arm 12 designed to engage with an escape wheel 30, the inlet arm 11 and the outlet arm 12 each comprising pallet stones 25, 26, the pallet stone 25 on the inlet arm 11 and / or the pallet stone 26 on the outlet arm 12 having a side wall located opposite the locking surface, the side wall having a portion curved inward toward the interior of the pallet stones 25, 26.

Description

Technical Field

[0001] The present invention relates to an anchor provided with a curved pallet for a timepiece escapement mechanism, an escapement mechanism provided with such an anchor, and a timepiece movement.

Background Art

[0002] In most mechanical timepieces, the energy required to rotate the hands (e.g., the minute hand and the hour hand) is stored in a fusee, and then released by a spring-type fusee system comprising a flywheel called a templet in combination with a strip-shaped spring wound in a spiral called a hairspring.

[0003] The inner end of the hairspring is attached to an arbor that rotates with the templet, the outer end of the hairspring is attached to a stud attached to a stud holder, and the stud holder itself is attached to a fixed bar (or cock).

[0004] The rotation of the templet is maintained by an escapement mechanism, and its vibrations are counted. The escapement mechanism comprises an anchor driven by a low-amplitude oscillatory motion, and the anchor is provided with two or three pallets that engage with the teeth of an escape wheel. When engaged in this way, the escape wheel is forced into a stepwise rotational motion at a frequency determined by the oscillation frequency of the anchor. The oscillation frequency of the anchor is set to the oscillation frequency of the spring-type templet.

[0005] In a conventional escapement mechanism, the oscillation frequency is about 4 Hz, i.e., about 28,800 oscillations per hour (A / h). Excellent watchmakers aim to ensure that the spring-type templet oscillates isochronously and stably (i.e., the rate remains constant).

[0006] The anchor in the escapement mechanism is designed to provide a mechanical connection between the templet and the escape wheel. Therefore, the positioning of the anchor is important to ensure that the anchor engages accurately with the other two components.

[0007] Generally, the anchor is formed by a monoblock body comprising a fork that engages with an ellipse on the balance wheel and at least two arms that engage with the escapement, often each equipped with a pallet stone. The body of the anchor is mounted on an arbor, which has pivots at each end. During assembly, the pivots are inserted into bearings located on bars or plates.

[0008] Today, the hairspring can be replaced with a flexible guide as a spring that forms a virtual pivot. Flexible guides with virtual pivots allow for significant improvements to the oscillator of a watch. The simplest is the cross-blade pivot, which consists of two guides with linear intersecting blades. These two blades are three-dimensional in two different planes or two-dimensional in the same plane, in the latter case welded together at the intersection. However, there are also RCC (Remote Center Compliance) guides with non-intersecting linear blades. Such oscillators are described in European Patent Application Publication No. 14199039 and European Patent Application Publication No. 16155039.

[0009] However, with such a flexible guide, the amplitude of the balance wheel is much smaller, and the rotation angle is about 20 degrees, whereas with a spring-loaded balance wheel, the rotation angle is 330°, and the balance wheel vibrates at a much higher frequency than a balance wheel attached to a hairspring.

[0010] Therefore, a new escapement mechanism configuration was invented that functions in conjunction with a speed control mechanism equipped with a flexible guide.

[0011] In most mechanical movements, the escapement arbor, lever arbor, and spring-loaded balance arbor are in the same plane. Viewed from above, the positions of these three axes form a straight line. This is known as an in-line arrangement. However, this arrangement is quite bulky.

[0012] In certain watch movement configurations, the positions of the three axes form a bend. In other words, the escapement, anchor, and balance wheel are not aligned in a straight line, but are arranged in a triangular shape, with each located at the vertex of the same triangle. This arrangement makes it possible to reduce the size of the watch movement.

[0013] Generally, the anchor fork and the pallet stone on the anchor are located at the same level within the movement. Furthermore, since the fork engages with the ellipse on the balance wheel and the pallet stone engages with the teeth of the escapement, the fork and pallet stone must be kept apart from each other to prevent collision between the ellipse and the teeth of the escapement. This explains why a linear "arrangement" is generally used.

[0014] Therefore, on the one hand, the relative position between the anchor and the escapement, particularly the center distance, must be clearly defined. On the other hand, the relative position between the anchor and the balance wheel, particularly the center distance, must also be clearly defined.

[0015] Since the pallet stone and fork generally belong to the same part (anchor) and engage at essentially the same level, it is difficult to satisfy both requirements simultaneously.

[0016] In a Swiss lever mechanism, the escapement has multiple teeth with impulse beaks that extend at least partially tangentially to the escapement, toward the rear of the teeth with respect to the direction of rotation of the escapement. Such impulse beaks provide a larger impulse surface for contacting the pallet stone on the anchor.

[0017] However, this configuration of teeth increases the risk of collision with the palpation stone on the ankle because the teeth are enlarged. In fact, the palpation stone should not touch the sides of the teeth on the ankle as it moves between the two teeth to lock the wheel.

[0018] Therefore, the placement of the palpeal stone relative to the ankle teeth is important. It is necessary to design and make available palpeal stones that can engage with such teeth.

[0019] The levers used in known Swiss lever mechanisms feature synthetic or ceramic pallet stones with straight walls.

[0020] To avoid collisions, the palpable stones are positioned on the ankle so that they move between the teeth at the minimum safe distance away from the teeth.

[0021] However, the larger the safety distance, the greater the impact on the mechanism's performance, and the mechanism's performance deteriorates significantly.

[0022] Furthermore, the new technology makes it possible to manufacture parts using innovative materials that possess specific advantages. For example, silicon parts can be manufactured. [Overview of the project] [Problems that the invention aims to solve]

[0023] The present invention aims to provide an anchor for a Swiss lever escapement that avoids the aforementioned drawbacks and, in particular, improves the performance of the escapement while maintaining a sufficient safety distance between the pallet stone on the anchor and the teeth of the escapement wheel during the operation of the escapement mechanism. [Means for solving the problem]

[0024] For this purpose, the present invention relates to an escapement for a watch equipped with a Swiss lever (Swiss anchor), the anchor comprising a fork designed to engage with an ellipse on the balance wheel, and an inlet arm and an outlet arm designed to engage with an escapement wheel, the inlet arm and the outlet arm each comprising a pallet stone, the pallet stone being designed to engage with the teeth of the escapement wheel.

[0025] The present invention is noteworthy in that the claw stone on the inlet arm and / or the claw stone on the outlet arm are provided with a side wall located opposite the locking surface, and the side wall has a portion that curves inward toward the interior of the claw stone.

[0026] This curved portion increases the safety distance between the pawl stone and the teeth of the escapement wheel, particularly with respect to the impulse peak. However, the curved portion ensures the sufficient performance of the escapement mechanism.

[0027] In fact, due to the curved portion, it becomes possible to reduce the thickness of the pawl stone in a specific zone, which is the zone closest to the teeth of the escapement wheel.

[0028] According to a specific embodiment of the present invention, the pawl stone on the inlet arm comprises an outer side wall having a curved portion.

[0029] According to a specific embodiment of the present invention, the pawl stone on the outlet arm comprises an inner side wall having a curved portion.

[0030] According to a specific embodiment of the present invention, the side wall of the pawl stone is designed to avoid contact with the teeth of the escapement wheel.

[0031] According to a specific embodiment of the present invention, the curved portion comprises two facets that form an angle from 90° to 160°, preferably from 105° to 150°, or from 120° to 140°.

[0032] According to a specific embodiment of the present invention, the pawl stone comprises an impulse surface that forms an angle with the outer surface, and the angle is preferably from 20° to 70°, or from 30° to 60°.

[0033] According to a specific embodiment of the present invention, the pawl stone is at least partially, preferably completely, formed from a material containing silicon.

[0034] According to a specific embodiment of the present invention, the anchor is preferably completely formed from a material containing silicon.

[0035] According to a specific embodiment of the present invention, the anchor comprises a fork, an inlet arm, and an arbor to which the outlet arm is attached.

[0036] The present invention also relates to an escapement mechanism comprising an escapement wheel having a toothed portion with multiple teeth, and an anchor thereof.

[0037] According to a particular embodiment of the present invention, a plurality of teeth are provided with impulse beaks.

[0038] The present invention also relates to a watch movement comprising a plate, a balance wheel, a balance bridge, and a flexible guide, wherein the balance wheel is suspended by the flexible guide, and the escapement mechanism is such as that described.

[0039] According to certain embodiments of the present invention, the balance wheel, escapement wheel, and anchor are arranged to form a bend having an angle of less than 90°, preferably less than 70°, or less than 60°. [Brief explanation of the drawing]

[0040] Other features and advantages of the present invention will be better understood by reading the following description relating to specific embodiments of the invention, which are provided merely as illustrative and non-limiting examples, and by the accompanying drawings. [Figure 1] This is a schematic top view of a clock module equipped with a regulating mechanism and an escapement mechanism. [Figure 2] Figure 1 is a schematic side view of the clock module. [Figure 3] Figures 1 and 2 show schematic cross-sectional views of a watch movement equipped with the watch module. [Figure 4] This is a schematic top view of an escapement mechanism equipped with a clock wheel according to a third embodiment of the present invention. [Figure 5] Figure 4 is an enlarged schematic top view of a part of the escapement mechanism. [Figure 6] This is a schematic perspective view of the anchor according to the present invention. [Modes for carrying out the invention]

[0041] In Figures 1 and 2, the clock module 10 is equipped with a Swiss lever escapement mechanism 50 that works in conjunction with the regulator 60.

[0042] The governor 60 comprises a balance wheel 35 and a rotatable flexible guide 32 for the balance wheel 35, and the escapement mechanism 50 comprises an escape wheel 30 and an anchor 21.

[0043] The balance wheel 35 has a bone-like shape, comprising a longitudinal portion 36 and arc-shaped lateral portions 37 at each end of the longitudinal portion 36. The balance wheel 35 further includes a stopper concentric with a virtual axis of rotation located in the center of the longitudinal portion 36, and screws 39 located in the lateral portions 37 for setting the inertia of the balance wheel.

[0044] The balance wheel 35 is attached to a flexible guide 32 to enable it to perform rotational oscillating motion around a virtual axis of rotation. The flexible guide 32 is directly connected to the balance wheel 35.

[0045] The flexible guide 32 includes at least two flexible blades 37, in this embodiment, two pairs of intersecting flexible blades 37 arranged in series to form a double pivot and increase the rotation angle of the balance wheel 35.

[0046] The escapement wheel 30 comprises a hub 3, two sets of blades 5 and 16, and an outer circumferential tooth portion 24. The outer circumferential tooth portion 24 has teeth 28 positioned at the joint between the free end of the first set of blades 5 and the free end of the second set of blades 16. Furthermore, the second set of blades 16 is curved.

[0047] The teeth 28 are bent to form an impulse beak that extends at least partially tangentially to the escapement wheel 30 toward the rear of the teeth 18 with respect to the rotational direction of the escapement wheel 30.

[0048] The escapement mechanism 50 further includes a second clock wheel 20 that meshes with the first escapement wheel 30. For example, the second clock wheel 20 is a seconds wheel. The teeth 14 of the second clock wheel 20 mesh with the pinion 3 of the first escapement wheel 30.

[0049] The balance wheel 35 is equipped with an ellipse 23 that extends below the balance wheel 35 and engages with a fork 22 on the anchor 21. The ellipse 23 is attached to the balance wheel 35.

[0050] The centers of the balance wheel 35, escapement wheel 30, and anchor 21 are positioned on a line that forms a bend. This is in contrast to conventional escapement mechanisms in which this line is substantially straight and the anchor is positioned on this line between the balance wheel and escapement wheel.

[0051] Therefore, the balance wheel 35, escapement wheel 30, and anchor 21 are each positioned at the vertices of the triangle.

[0052] The angle of the bend is less than 90°, preferably less than 70°, or less than 60°. Therefore, the balance wheel 35, escapement wheel 30, and anchor 21 are compactly arranged.

[0053] The anchor 21 is equipped with two arms 11, 12, namely an inlet arm 11 and an outlet arm, the ends of which are equipped with pallet stones 25, 26 that engage with the teeth 18 of the escapement wheel 30, respectively.

[0054] The pallet stones 25 and 26 on the arms 11 and 12 of the anchor 21 engage with the escapement 30 and alternately interact with the teeth 18 of the escapement 30 to adjust the rate.

[0055] The anchor 21 also includes a longitudinal portion 14 that extends laterally, the longitudinal portion 14 having a fork 22 at its end that engages with an ellipse 23 on the balance wheel 35.

[0056] Furthermore, the anchor 21 is equipped with an arbor 5 substantially perpendicular to the longitudinal portion 14 and the fork 22, thereby allowing the anchor 21 to be mounted to rotate within the movement.

[0057] The ankle 21 comprises an elongated body 31 extending radially, the body 31 being positioned to engage with a stopper not shown in the drawing. The purpose of the stopper is to prevent the ankle 21 from rotating excessively.

[0058] The elongated body 31 is positioned at essentially the same level as the entrance arm 11 and exit arm 12 of the ankle 21.

[0059] The fork 22 and the inlet arm 11 and outlet arm 12 are positioned on two parts of the arbor 5. The fork 22 is positioned on the first level of the arbor 5, and the inlet arm 11 and outlet arm 12 are positioned on the second level of the arbor 5.

[0060] In this way, the two levels are separated by a predetermined distance D0 along the axis of the arbor 5. Preferably, this distance is between one-quarter and three-quarters of the length of the arbor.

[0061] For example, the first level is effectively located at the bottom edge of the arbor, and the second level is effectively located in the center of the arbor.

[0062] Preferably, the arbor 5 has a length substantially corresponding to the height of the clock movement starting from the plate 2.

[0063] In Figure 3, the clock modules of Figures 1 and 2 are arranged in a clock movement 1, specifically for a wristwatch.

[0064] In addition to the clock module 10, the clock movement 1 includes a plate 2 and bars for supporting the components within the clock module 10.

[0065] In particular, the watch movement 1 includes a balance bridge 4 positioned above the balance wheel 4. Thus, the balance wheel 4 oscillates between the plate 2 and the balance bridge 4. For example, the balance bridge 4 includes an upper stopper for fixing the balance wheel 35 vertically.

[0066] The clock movement 1 also includes an escapement bar 6 for holding the axle of the escapement wheel 30 in motion.

[0067] The escapement wheel 30 is mounted to pivot between the plate 2 and the escapement bar 6. The balance wheel 35 is therefore mounted to pivot between the balance bridge 4 and the plate 2.

[0068] The arbor 5 includes a first pivot 7 located at the first end of the arbor 5 and a second pivot 8 located at the second end of the arbor 5.

[0069] The first pivot 7 is mounted to pivot on the plate 2, and the second pivot 8 is mounted to pivot within the balance bridge 4. The anchor 21 is therefore mounted to pivot between the balance bridge 4 and the plate 2. The arbor 5 also extends beyond the balance wheel 35.

[0070] For this purpose, the balance bridge 6 comprises a first bearing 13 for the balance wheel 37, which functions as a stopper in the event of a collision and is concentric with a virtual axis of rotation defined by the flexible guide 32, and a second bearing 15 for the anchor 21. The distance D1 between the center of the first bearing 13 and the center of the second bearing 15 is predetermined to allow for optimal engagement between the fork 22 on the anchor 21 and the ellipse 23 on the balance wheel 6.

[0071] Plate 2 includes a third bearing 16 for the balance wheel 35, a fourth bearing 17 for the arbor 5 on the anchor 21, and a fifth bearing 9 for the escapement wheel 30. The distance D2 between the center of the fourth bearing 17 and the center of the fifth bearing 19 is predetermined to allow for optimal engagement between the arms 11 and 12 on the anchor 21 and the escapement wheel 30.

[0072] The escapement bar 6 is equipped with a sixth bearing 24 for pivoting on the escapement wheel 30.

[0073] This arrangement of the anchor 21 ensures more secure engagement between the arms 11 and 12 on the anchor 21 and the escapement 30, on the one hand, and between the fork 22 and the ellipse 23, on the other hand. In fact, the arbor 5 is less likely to be excessively tilted relative to the plate 2.

[0074] Since the anchor 21 and balance wheel 35 are positioned between the plate 2 and the balance bridge 4, the distance D1, which is the center distance between the first pivot 8 of the balance wheel 35 on the balance bridge 4 and the pivot of the anchor 21, is constant and unlikely to change during assembly.

[0075] Similarly, the distance D2, which is the center distance between the first pivot 7 of the anchor on plate 2 and the pivot of the escapement wheel 30, is constant and does not change during assembly.

[0076] According to the present invention, in Figures 4 to 6, the pallet stone 25 of the entrance arm 11 and the pallet stone 26 of the exit arm 12 on the anchor 21 are provided with side walls 27 and 28 having curved portions 29 and 33.

[0077] In this embodiment, the two pallet stones 25 and 26 each have side walls 27 and 28 having curved portions 29 and 33, respectively.

[0078] The curved portions 29 and 33 are located on the sides of the pallet stones 25 and 26 that face the free ends of the teeth 18. Therefore, the side walls 27 and 28 of each pallet stone 25 and 26 are located on the opposite side from the locking surface.

[0079] The claw stone 25 on the entrance arm 11 has an outer wall 27 that curves inward toward the interior of the claw stone 25, and the claw stone 26 on the exit arm 12 has an inner wall 27 that curves inward toward the interior of the claw stone 26.

[0080] In this embodiment, the curved portions 29, 33 are provided with two small faces 34, 39 that form angles from 90° to 160°, preferably from 105° to 150°, or from 120° to 140°.

[0081] Each pallet stone 25, 26 is provided with an impulse surface 42 that forms an angle with the side walls 27, 28, the angle of which is preferably 20° to 70° or 30° to 60°.

[0082] The pallets 25 and 26 are formed at least partially, preferably entirely, from a silicon-containing material. In fact, this material makes it possible to manufacture the curved portions 26 and 29.

[0083] Preferably, the ankle 21 is formed entirely, preferably completely, from a silicone-containing material. Thus, the ankle 21 is preferably made integrally with the palp stones 25 and 26 and made from the same material.

[0084] Naturally, the present invention is not limited to the embodiments described with reference to the drawings, and modifications can be envisioned without departing from the scope of the present invention.

Claims

1. An escapement (21) for a watch escapement (50) with a Swiss lever, the escapement (21) comprising a fork (22) designed to engage with an ellipse (23) on a balance wheel (35), and an inlet arm (11) and an outlet arm (12) designed to engage with an escape wheel (30), wherein the inlet arm (11) and the outlet arm (12) each comprise pallet stones (25, 26), and the pallet stone (25) on the inlet arm (11) and / or the pallet stone (26) on the outlet arm (12) comprises side walls (27, 28) located opposite to the locking surface, the side walls (27, 28) having portions (29, 33) curved toward the interior of the pallet stones (25, 26).

2. The ankle according to claim 1, characterized in that the pallet stone (25) on the entrance arm (11) is provided with an outer side wall (27) having the curved portion (29).

3. The anchor according to claim 1, characterized in that the pallet stone (26) on the exit arm (12) has an inner side wall (28) having the curved portion (33).

4. The anchor according to claim 1, characterized in that the side walls (27, 28) of the pallet stones (25, 26) are designed to avoid contact with the teeth (18) of the escapement wheel (30).

5. The ankle according to claim 1, characterized in that the curved portion (29, 33) comprises two small faces (34, 39) that form an angle of 90° to 160°, preferably 105° to 150°, or 120° to 140°.

6. The ankle according to claim 1, characterized in that the pallet stones (25, 26) have impulse surfaces (42) that form an angle with the side walls (27, 28), and the angle is preferably 20° to 70° or 30° to 60°.

7. The ankle according to claim 1, characterized in that the palp stones (25, 26) are formed at least partially, preferably completely, from a material containing silicon.

8. The ankle according to claim 1, characterized in that it is preferably entirely formed from a material containing silicon.

9. The ankle according to claim 1, characterized in that it comprises an arbor (5) to which the fork (22), the inlet arm (11), and the outlet arm (12) are attached.

10. A Swiss lever escapement mechanism comprising an escape wheel (30) having a toothed portion having a plurality of teeth (18), wherein the escape wheel (30) comprises the lever (21) described in claim 1.

11. The escapement mechanism according to claim 10, characterized in that the plurality of teeth (18) are provided with impulse beaks (43).

12. A watch movement comprising a plate (2), a balance wheel (35), a balance bridge (4), and a flexible guide (32), wherein the balance wheel (35) is suspended by the flexible guide (32) and can oscillate about a virtual axis between the plate (2) and the balance bridge (4), and is characterized in that it comprises the escapement mechanism described in claim 10.

13. The watch movement according to claim 12, characterized in that the balance wheel (4), the escapement wheel (30), and the anchor (21) are arranged to form a bent portion having an angle of less than 90°, preferably less than 70°, or less than 60°.

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