Tourbillon mechanism for a timepiece movement

Abstract

The invention relates to a tourbillon mechanism (1) for a timepiece movement, the tourbillon mechanism comprising: - a rotary support (3) pivotably mounted on a base (5) so as to pivot about a first axis of rotation (A1) and arranged to be rotated by a drive source (S); - an oscillator (7) pivotably mounted on the rotary support (3) so as to pivot about a second axis of rotation (A2); - a blocking member (11) mounted on the rotary support (3) and arranged to block and release rotations of the rotary support (3) under the control of the rotations of the oscillator (7); - an escape wheel (9) mounted so as to rotate as one with the base (5) and arranged to co-operate with the blocking member (11); - a direct impulse member (15) mounted on the second axis of rotation (A2) and arranged to co-operate with the escape wheel (9) so as to deliver an impulse to the oscillator (7) during the pivoting of the rotary support (3).

Description

Description TOURBILLON MECHANISM FOR WATCH MOVEMENT Technical field

[0001] The present invention relates to the field of watchmaking. It relates, more particularly, to a tourbillon mechanism for a watch movement. State of the art

[0002] Document CH701490 describes a tourbillon with a “Potter” type escapement with a fixed escape wheel.

[0003] In this mechanism, the balance-spring oscillator is mounted in a rotating cage arranged to be driven in rotation by a driving source, the axis of rotation of the balance being coaxial with that of the cage. The latter also carries an anchor, which cooperates on the one hand with the oscillator in a known manner, and on the other hand with a fixed escape wheel mounted so as to rotate with a frame element.

[0004] This construction minimizes the number of elements carried by the cage and the angular inertia of the tourbillon, and thus allows a relatively fast rotation speed of the cage, on the order of a few seconds, which is significantly faster than the 30 seconds to several minutes of a conventional tourbillon.

[0005] This type of escapement has also found application in multi-axis tourbillons, notably in the triaxial tourbillons used in the MB&F Legacy Machine Thunderdome piece. These triaxial tourbillons have rotational speeds of the three cages of 8, 12 and 20 seconds respectively, with the escape wheel attached to the intermediate cage.

[0006] However, the Potter type escapement generates relatively high friction, which results in fairly low efficiency and is detrimental to the power reserve.

[0007] Document CH718204 discloses, in one of its embodiments, an escapement in which an escapement crown with internal teeth The fixed escapement cooperates with a linear displacement escapement organ which provides indirect impulses to the balance-spring oscillator in a manner similar to a classic Swiss anchor. This system is very thin and fragile, and is therefore difficult to develop. In addition, the relatively high inertia of the chassis and the elements it carries as well as the friction generated by the movements of the escapement organ induce relatively weak indirect impulses (transmitted to the oscillator at the start of the pallets' disengagement) as well as a fairly low efficiency, which again harms the power reserve.

[0008] The aim of the invention is therefore to provide a tourbillon mechanism in which the aforementioned defects are at least partially overcome. Disclosure of the invention

[0009] More specifically, the invention relates to a tourbillon mechanism for a watch movement, as defined by claim 1. This mechanism comprises:

[0010] - a rotating support, such as a plate, a cage or the like, pivotally mounted on a base around a first axis of rotation and arranged to be driven in rotation by a driving source such as a mainspring housed in a barrel;

[0011] - an oscillator, typically a sprung balance of any known type, pivotally mounted on said rotary support around a second axis of rotation;

[0012] - a locking member mounted on said rotary support and arranged to lock and release rotations of said rotary support under the direct or indirect control of the rotations of said oscillator;

[0013] - an escape wheel mounted to rotate with said base and arranged to cooperate with said locking member;

[0014] - a direct impulse member (such as an impulse pallet) mounted on said second axis of rotation and arranged to cooperate with said escape wheel (in particular by direct cooperation with the teeth of this last) so as to provide an impulse to said oscillator when said rotary support pivots.

[0015] The escapement described above is of the so-called "direct impulse" type, and has a high efficiency compared to a conventional anchor escapement, which makes it possible to increase the power reserve of the movement in which said tourbillon mechanism is integrated, while maintaining the relatively high rotation speed of the rotating support of the "Potter" escapement. It should be noted that the term "tourbillon" is to be understood in the broad sense.

[0016] Advantageously, said locking member is a trigger lever pivotally mounted on said rotary support about a third axis of rotation. This trigger lever is arranged to cooperate with a release pallet mounted on said second axis in order to pivot said trigger lever to trigger a rotation of said rotary support, said trigger lever being subjected to a return force tending to keep it engaged with said escape wheel.

[0017] Advantageously, a retractable finger is mounted in rotation on said trigger lever around a fourth axis of rotation so as to cooperate with said release pallet to pivot said trigger lever to trigger the rotation of the rotary support during a first alternation of the oscillator, and to retract to allow said release pallet to pass during a second alternation of the oscillator.

[0018] Advantageously, said retractable finger is subjected to a return force provided by an elastic element which tends to keep it pressed against a stop carried by said trigger lever.

[0019] Alternatively, said blocking element is an anchor.

[0020] Advantageously, said second axis of rotation is distinct from said first axis of rotation, but these two axes can also be merged.

[0021] Advantageously, said second axis of rotation makes an angle of 1° to 90°, preferably 10° to 80°, more preferably 20° to 70°, relative to said first axis of rotation, which improves the running in the flat and hanging positions of the timing test. Brief description of the drawings

[0022] Other details of the invention will appear more clearly on reading the following description, given with reference to the appended drawings in which: - Figures 1 and 2 are isometric schematic views of a non-limiting embodiment of a tourbillon mechanism according to the invention, at rest; - Figures 3 to 9 are schematic plan views of a mechanism according to Figures 1 and 2 illustrating the sequence of operation, the balance and the base having been omitted. Embodiments of the invention

[0023] Figures 1 and 2 schematically illustrate a tourbillon mechanism 1 according to the invention, the term "tourbillon" being understood in the broad sense. This mechanism 1 comprises a rotary support 3 pivotally mounted on a base 5 around a first axis of rotation A1, and is arranged to be driven in rotation by means of a driving source S, such as a barrel housing a mainspring, in a known manner. The driving source S has been shown schematically in Figure 1, and the kinematic connection allowing it to drive the rotary support 3 in rotation has been illustrated in the form of an arrow, this kinematic connection being able to take any known form, comprising toothed wheels, chains, belts or the like.

[0024] In the situation illustrated by figures 1 and 2, the rotary support 3 is at rest, the driving source S tending to make it pivot clockwise according to the orientation of the figures, as will clearly follow later. In the illustrated embodiment, the rotary support 3 is a board provided with bars which are integral therewith in rotation, the board being supported in a flying manner by ad hoc bearings, but the rotary support 3 can also be formed of a simple board, a flying cage or one pivoted in a conventional manner between bearings, or any other suitable structure.

[0025] Base 5 may be integral with the movement frame, or part of it, or may alternatively be mobile in the case where the tourbillon mechanism 1 is biaxial or triaxial, according to the principles of biaxial and triaxial tourbillons by Richard Good, or the MB&F Legacy Machine Thunderdome piece mentioned in the introduction.

[0026] The rotating support 3 carries a balance wheel 7 - balance spring type oscillator (not shown, but arranged in a conventional manner to provide a return torque to oscillate the balance wheel 7, in a known manner) pivotally mounted on the rotating support 3 around a second axis of rotation A2. Of course, other suitable spring shapes known to those skilled in the art (helical, spherical, double balance spring, etc.) may be envisaged. This axis A2 may be the same as the axis A1, or, as shown, offset relative to the latter. Furthermore, the axis A2 may be inclined relative to the axis A1, at a rate of 1° to 90°, preferably 10° to 80°, more preferably 20° to 70°, where appropriate, instead of being parallel to it.

[0027] Moving now to the escapement, the escape wheel 9 is coaxial with the axis A1, and is rotationally fixed to the base 5.

[0028] As illustrated, the escape wheel 9 is hollow in its center and has edge teeth, but it can be internally toothed as in document CH701490, or in the form of a crown with external teeth.

[0029] The key point of the invention is that the escapement is of the direct impulse type, that is to say that at least part of the force for maintaining the oscillator is provided by the cooperation between, on the one hand, the escape wheel, and on the other hand a structure carried by the balance staff (such as an impulse pallet), without passing through a member which also acts as a blocking member (such as an anchor, which provides indirect impulses). The classic example of an escapement which maintains the oscillator purely by direct impulse is the detent escapement, in which the blocking member of the escape wheel only serves to block and release the latter, the impulses being provided directly, once per oscillation, by the cooperation between the teeth of the escape wheel and an impulse pallet rotating with the balance shaft. The classic example of an indirect impulse escapement is the Swiss lever escapement, in which the lever serves as both a blocking and impulse transmission device, the cooperation between the tops of the escape wheel teeth and the oblique impulse planes of the pallets generating the impulses which are transmitted to the oscillator via the lever at the roller pin.Finally, an example of a "hybrid" direct impulse escapement that incorporates not only direct impulses but also indirect impulses is the Omega-Daniels coaxial escapement, in which the impulses in one direction of oscillator rotation are provided by the cooperation between the escape wheel and an impulse pallet in a similar way to the case of a detent escapement, while in the other direction of oscillator rotation the impulses are provided via an anchor.

[0030] Returning to the tourbillon mechanism 1 of the invention, which is direct impulse as mentioned above, for this purpose, the rotary support 3 carries, as a locking member, a detent lever 11, pivotally mounted on the rotary support 3 about a third pivot axis A3. Near, or at, a first end of the detent lever 11, there is a locking pallet 11a which cooperates with the teeth of the escape wheel 9 to block and release the rotation of the rotary support 3. A restoring force F is provided, which tends to keep the locking pallet 11a engaged with a tooth of the escape wheel 9, as is the case in Figures 1 and 2. This force F can be provided by an ad hoc elastic element, and the detent lever 11 can alternatively cooperate directly with the teeth of the escape wheel 9 instead of being provided with a pallet 11a.A first stop 12, mounted on the rotary support 3, is arranged to limit the rotation of the trigger lever 11 and thus limit its maximum position when it is under the effect of the force F.

[0031] The other end of the trigger lever 11 carries a retractable finger 11b which cooperates with a release pallet 13, the latter being integral in rotation with the balance 7. The angle of the end of the release pallet may be parallel to the second axis A2 or may be parallel to the first axis A1 at the point where it cooperates with the retractable finger 11b, or any intermediate angle, or else of a domed shape. In addition, this release paddle 13 may take any other ad hoc shape, such as a finger, a pin or any other element fulfilling this function.

[0032] The retractable finger 11b is pivotally mounted on the detent lever 11 about an axis A4 and is subjected to a restoring force provided by an elastic element 14 in order to constrain it against a second stop 11c so that the release pallet 13 can cooperate with the retractable finger 11b in order to pivot the detent lever 11 to move the blocking pallet 11a away from the teeth of the escape wheel 9 when the release pallet 13 pivots in a first direction (counterclockwise according to the orientation of the figures). When the release pallet 13 cooperates with the retractable finger 11b in the other direction of rotation (clockwise), the retractable finger 11b can move in rotation relative to the detent lever 11 against the effect of the elastic element 14 to allow the passage of the release pallet 13.

[0033] In order to provide impulses to the balance 7, an impulse pallet 15 is also provided, integral in rotation with the balance 7 and arranged to cooperate directly with the teeth of the escape wheel 9 during the pivoting of the rotary support 3. When the rotary support 3 is at rest (as in figures 1 and 2), the teeth of the escape wheel 9 are out of range of the impulse pallet 15, and no interaction between these elements takes place.

[0034] Although a detent system has been illustrated in the figures, other types of direct impulse escapement are possible. For this purpose, we can cite in particular a Swiss anchor escapement (which acts as a blocking member and which provides indirect impulses to the balance 7 in a known manner) combined with an impulse pallet 15 integral in rotation with the balance 7 and which cooperates directly with the teeth of the escape wheel 9 or an impulse wheel with edge or internal teeth which is mounted integral in rotation with the escape wheel 9 on one side or the other of the latter, or any other direct impulse escapement (such as for example an Omega-Daniels escapement) which is suitable for modification to include a fixed escape wheel 9. For the remainder, the blocking member 11 may be a cam or any other suitable element.

[0035] The operating sequence of the tourbillon 1 according to the invention will now be described with reference to Figures 3 to 9.

[0036] As a reminder, in the views of Figures 1 and 2, the rotary support 3 is at rest, and the locking pallet 11a is in contact with a tooth of the escape wheel 9. The balance 7 is pivoting counterclockwise, and the release pallet 13 comes into contact with the second end 11b of the detent lever 11.

[0037] Looking now at Figure 3, the release pallet 13 has begun to cooperate with the retractable finger 11b to pivot the detent lever 11 about its pivot axis A3 and to lift the blocking pallet 11a, which is about to cross the top of a tooth of the escape wheel 9. At the same time, the impulse pallet 15 enters the circle defined by the teeth of the escape wheel 9.

[0038] In Figure 4, the release pallet 13 has lifted the detent lever 11 so that the locking pallet 11a comes out of the toothing of the escape wheel 9, and the rotating support 3 begins to pivot clockwise. In doing so, the impulse pallet 15 comes into contact with a tooth of the escape wheel 9, and receives an impulse from this tooth.

[0039] By pivoting further, and as illustrated in Figure 5, the release paddle 13 no longer cooperates with the retractable finger 11b, and the restoring force F begins to cause the trigger lever 11 to pivot counterclockwise around its pivot axis A3.

[0040] In Figure 6, the detent lever 11 has returned to its starting position, with reference to the rotating support 3, under the effect of the restoring force F, and re-enters the toothing of the escape wheel 9, its position angular relative to the rotary support 3 being defined by the first stop 12 against which the trigger lever 11 bears.

[0041] The pivoting of the rotary support 3 continues clockwise under the effect of the driving source, as illustrated in Figure 7.

[0042] Figure 8 illustrates the situation in which the rotating support 3 is again at rest, the blocking pallet 11a now being in contact with the next tooth of the escape wheel 9. The balance 7 is free to finish its counterclockwise alternation and to begin its clockwise alternation.

[0043] In doing so, and as illustrated in Figure 9, when the release paddle 13 comes into contact with the retractable finger 11b, the latter is lifted against the force provided by the elastic element 14. Since the first stop 12 has a sufficient length to cooperate with the trigger lever 11 but does not reach the retractable finger 11b, the latter is not prevented from pivoting around its axis of rotation A4 to allow the release paddle 13 to pass.

[0044] Then the operating cycle repeats.

[0045] As for the materials that can be used, the entire range of materials used in contemporary watchmaking can be considered (metals, non-metals such as silicon, silicon compounds, synthetic diamond, sapphire, structurable glasses, ceramics, glass-ceramics, metallic glasses, polymers, composites, materials capable of additive manufacturing, etc.).

[0046] For the remainder, the trigger lever 11 can be provided in a single piece, integral with the elastic element which provides the return force F. In addition, the trigger lever 11 (or more generically the blocking element which can, as a reminder, alternatively be an anchor or similar) can be supported on the rotary support 3 by a system of flexible pivots, its pivot axis A3 therefore being virtual and defined by the flexible pivots. More generally, an implementation with flexible pivots makes it possible to eliminate, for example, the first stop 12 if the latter is integrated in a flexible pivot trigger lever, and also allows at least some axes to be made virtual instead of physical.

[0047] As regards the shape and arrangement of the various elements, there is no limitation, as long as the operation described above is achieved.

[0048] This description has been given as a non-limiting illustration of the invention. Those skilled in the art may add additions within its scope, without, however, departing from the scope of the invention defined by the claims.

Claims

Claims 1. Tourbillon mechanism (1) for a watch movement, comprising: - a rotary support (3) pivotally mounted on a base (5) around a first axis of rotation (A1) and arranged to be driven in rotation by a driving source (S); - an oscillator (7) pivotally mounted on said rotary support (3) around a second axis of rotation (A2); - a locking member (11) mounted on said rotary support (3) and arranged to lock and release rotations of said rotary support (3) under the control of the rotations of said oscillator (7); - an escape wheel (9) mounted integral in rotation with said base (5) and arranged to cooperate with said locking member (11); - a direct impulse member (15) mounted on said second axis of rotation (A2) and arranged to cooperate with said escape wheel (9) so as to provide an impulse to said oscillator (7) during the pivoting of said rotary support (3).

2. Tourbillon mechanism (1) according to the preceding claim, wherein said locking member (11) is a detent lever (11) pivotally mounted on said rotary support (3) about a third axis of rotation (A3) and arranged to cooperate with a release pallet (13) mounted on said second axis in order to pivot said detent lever (11) to trigger a rotation of said rotary support (3), said detent lever (11) being subjected to a return force (F) tending to keep it engaged with said escape wheel (9).

3. Tourbillon mechanism (1) according to the preceding claim, wherein a retractable finger (11b) is rotatably mounted on said trigger lever (11) about a fourth axis of rotation (A4) so ​​as to cooperate with said release pallet (13) to pivot said trigger lever (11) to trigger rotation of said rotary support (3) during a first alternation of the oscillator (7), and to retract to allow said release vane (11b) to pass during a second alternation of said oscillator (7).

4. Tourbillon mechanism (1) according to the preceding claim, in which said retractable finger (11b) is subjected to a return force provided by an elastic element (14) which tends to keep said retractable finger (11b) pressed against a stop (11c) carried by said trigger lever (11).

5. A tourbillon mechanism (1) according to claim 1, wherein said locking element (11) is an anchor.

6. Tourbillon mechanism (1) according to one of the preceding claims, wherein said second axis of rotation (A2) is distinct from said first axis of rotation (A1).

7. A tourbillon mechanism (1) according to one of the preceding claims, wherein said second axis of rotation (A2) makes an angle of 1° to 90°, preferably 10° to 80°, more preferably 20° to 70°, relative to said first axis of rotation (A1).

8. Clockwork movement comprising a tourbillon mechanism (1) according to one of the preceding claims.

9. Timepiece comprising a movement according to the preceding claim.

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