TIMEPIECE MOVEMENT ESCAPEMENT, RETURN COMPONENT FOR TIMEPIECE ESCAPEMENTS, TIMEPIECE MOVEMENT AND TIMEPIECE COMPRISING SUCH A MOVEMENT

Abstract

The invention relates in particular to a return member for a balance wheel of a timepiece, replacing a spiral spring. This return member comprises a rake provided with a toothed sector arranged to work together with a balance wheel pinion. The rake has an axis of rotation allowing it to move between two extreme positions, called working positions, separated by a rest position. The return member also comprises two springs arranged to press the rake towards its rest position. Each spring is made up of an elastic blade arranged to store energy, then to return it to the rake. Each elastic blade works alternately so that they never work simultaneously. The invention also relates to an escapement comprising such a return member, a clockwork movement comprising this return member and a timepiece comprising such a movement.

Claims

1. A clockwork movement escapement, comprising: a balance wheel pivoting on an axis of rotation of the balance wheel; an escape wheel; a lever; and a return member of the balance wheel, wherein the balance wheel is integral with a balance wheel pinion, the return member of the balance wheel includes a rake provided with a toothed sector arranged to work together with the balance wheel pinion, the rake comprising an axis allowing its rotation between two extreme positions separated by a rest position, a return mechanism comprising two springs arranged to press the rake towards its rest position, the springs comprising elastic blades arranged to store energy and to return energy to the rake; and only one of the elastic blades stores and returns energy at the same time.

2. The clockwork movement escapement according to claim 1, wherein when the rake is in its rest position, the springs are arranged symmetrically relative to a plane passing through the axis of rotation of the balance wheel and the axis of rotation of the rake.

3. A return member for a timepiece movement, comprising: an escapement provided with a balance wheel, with an escape wheel and with a lever, the return member, includes a rake provided with a toothed sector arranged to work together with a balance wheel pinion, the rake having an axis allowing it to rotate between two extreme positions, called working positions, separated by a rest position; two springs arranged to press the rake towards its rest position, the springs comprising elastic blades arranged to store energy and to return energy to the rake; wherein only one of the elastic blades stores and returns energy at the same time.

4. The return member according to claim 3, wherein when the rake is in its rest position, the springs are arranged symmetrically relative to a plane passing through an axis of rotation of the balance wheel and through the axis of rotation of the rake.

5. The return member according to claim 3, wherein the rake includes internal teeth.

6. The return member according to claim 3, wherein the elastic blades are integral with the toothed sector.

7. The return member according to claim 3, wherein the elastic blades are arranged to lean against an arm of the rake.

8. A timepiece movement, comprising: an escapement provided with a balance wheel, with an escape wheel, a lever and a return member for the balance wheel, wherein the balance wheel is integral with a balance wheel pinion; in that the return member of the balance wheel includes a rake provided with a toothed sector arranged to work together with the balance wheel pinion, the rake comprising an axis allowing it to rotate between two extreme positions separated by a rest position; and a return mechanism having two springs arranged to press the rake towards its rest position, the springs comprising elastic blades arranged to store energy and to return energy to the rake; and only one of the elastic blades stores and returns energy at the same time.

9. The timepiece movement according to claim 8, wherein the movement includes at least two pins with which said elastic blades interact alternately during the motion of the rake around its axis of rotation.

10. The timepiece movement according to claim 8, further comprising a regulating element of the escapement.

11. The timepiece movement according to claim 10, wherein the regulating element of the escapement includes at least two pins movable on a plate of the movement and interacting with said springs.

12. A timepiece, comprising: a movement including an escapement provided with a balance wheel, an escape wheel, a lever and a return member for the balance wheel, wherein the balance wheel is integral with a balance wheel pinion; the return member of the balance wheel includes a rake provided with a toothed sector arranged to work together with the balance wheel pinion, the rake comprising an axis allowing it to rotate between two extreme positions separated by a rest position; and a return mechanism having two springs arranged to press the rake towards its rest position, the springs comprising elastic blades arranged to store energy and to return energy to the rake; and only one of the elastic blades stores and returns energy at the same time.

13. The timepiece according to claim 12, wherein the movement further includes at least two pins with which said elastic blades interact alternately during the motion of the rake around its axis of rotation.

14. The timepiece according to claim 12, wherein the movement further includes a regulating element of the escapement.

15. The timepiece according to claim 14, wherein the regulating element of the escapement includes at least two pins movable on a plate of the movement and interacting with said springs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The invention and its advantages will be better understood with reference to the appended figures and to the detailed description of particular embodiments, in which:

[0037] FIG. 1 is a top view of a classic Swiss lever escapement, without hairspring;

[0038] FIG. 2 is a profile view of the escapement of FIG. 1;

[0039] FIG. 3 is a profile view of the escapement of FIGS. 1 and 2, comprising a balance wheel shaft fitted with a pinion;

[0040] FIG. 4 is a top view of a part of the escapement of FIGS. 1 to 3, comprising a return member according to a first embodiment of the present invention, in a rest position;

[0041] FIG. 5 illustrates the return member of FIG. 4, in a rest position;

[0042] FIG. 6 illustrates the return member of FIG. 4, in a working position;

[0043] FIG. 7 is a top view of a variant of the return member of the invention, in a rest position;

[0044] FIG. 7a is an enlarged view of a part of FIG. 7;

[0045] FIG. 8 is a top view of the return member of FIG. 7, in a working position;

[0046] FIG. 9 illustrates a return member similar to the one of FIG. 6, in which an adjustment of the position of the elastic blades can be performed;

[0047] FIG. 10 represents a variant of the return member according to the invention, in a rest position;

[0048] FIG. 11 is a view of the return member of FIG. 10, in a working position;

[0049] FIGS. 12 to 14 illustrate other variants of return members according to the invention, in rest position;

[0050] FIG. 15 represents the return member of FIG. 14, in working position; and

[0051] FIG. 16 represents a return member with an internally toothed rake and a return mechanism identical to the one of FIGS. 14 and 15.

EMBODIMENT OF THE INVENTION

[0052] The invention relates in particular to a clockwork movement escapement. In the illustrated embodiments, the escapement comprises a conventional part and a new part. The conventional part is represented in FIGS. 1 to 3 by a part of a Swiss lever escapement. This escapement comprises a balance wheel 10 pivoting on a balance wheel shaft 11, a lever 12 pivoting on a lever shaft 13 and an escape wheel 14 pivoting on an escape wheel shaft 15. The lever 12 also comprises in a conventional manner, in particular a fork 16 actuated by the balance wheel 10 and two pallets 17 acting on teeth 18 of the escape wheel 14. Unlike conventional escapements, this escapement does not comprise any spiral spring. It should be noted that the Swiss lever escapement has been represented here, this escapement being the most commonly used in practice. A return member according to the invention could however also be used on any other escapement in which a balance wheel acts as a regulating member.

[0053] The new part comprises a return member 19 replacing the spiral spring in its function.

[0054] The return device according to the invention can be integrated into an existing escapement or form part of an escapement specifically developed for this movement.

[0055] With particular reference to FIG. 3, the balance wheel 10 used in the present invention comprises a balance wheel pinion 20 integral with the balance wheel shaft 11.

[0056] The return member 19 according to the present invention comprises a rake 21 comprising a toothed sector 22 and one or two arms 23. The rake 21 pivots around an axis of the rake 24 integral with a plate (not represented) of the clockwork movement. This rake can move on either side of its rest position, between two extreme working positions, in which the balance wheel 10 has made a maximum motion, clockwise or anti-clockwise.

[0057] The return member 19 further comprises a return mechanism 25 comprising two springs 26, the operation of which is described below. These springs 26 consist of two elastic blades 27 in the illustrated embodiments.

[0058] In the embodiment illustrated by FIGS. 4 to 6, the rake 21 comprises two arms 23, one end of which is arranged at each end of the toothed sector 22 and the other ends of which join near the axis 24 of rotation of the rake.

[0059] This rake 21 further comprises a rod 28 having one end close to the axis 24 of the rake and the other end integral with the elastic blades 27.

[0060] The return member 19 can be placed on a plate of a timepiece which has two pins 30 arranged so that the elastic blades 27 can lean against these pins depending on the position of the rack 21.

[0061] In this embodiment, the rake 21, the arms 23, the rod 28 and the elastic blades 27 are integral and are made in one piece.

[0062] FIGS. 4 and 5 illustrate the rake 21 in rest position. FIG. 6 illustrates the rake 21 in working position.

[0063] When the balance wheel 10 is pivoted in one direction, in a working position as illustrated for example by FIG. 6, the balance wheel pinion 20 acts on the toothed sector 22 of the rake 21 to cause the latter to pivot in the opposite direction, on its axis of rotation 24. This has the effect of deforming one of the elastic blades 27 against the corresponding pin 30 of the movement. This elastic blade 27 stores energy. The other elastic blade is free and does not interact with the rest of the movement, or with the other pin 30 so that it does not oppose the rotation of the rake 21 or of the balance wheel 10.

[0064] When the stress exerted by the elastic blade 27 is sufficient, after a certain angular motion of the rake 21 and therefore of the balance wheel 10, the blade returns energy and causes the rake to pivot in the other direction of rotation. This causes the rotation of the balance wheel via the balance wheel pinion 20. Conventionally, the balance wheel 10 acts on the lever 12 so as to release a tooth 18 of the escape wheel 14. An impulse plane of a tooth of the escape wheel 14 acts on one of the pallets 17 of the lever 12 so as to supply energy to this lever which transmits it to the balance wheel 10 via the fork 16. This energy is used by the balance wheel to pivot on its axis 11, which causes the rotation of the rake 21 on its axis 24 and makes it possible to load the other elastic blade 27 of the return mechanism 25.

[0065] This alternating movement is similar to the one generated by a hairspring. However, unlike the hairspring, the elastic blades 27 are symmetrical to each other when the rake is in rest position, which implies that there is no difference in operation when the balance wheel 10 pivots clockwise or counterclockwise.

[0066] The pins 30 can be mounted on an eccentric and thus form a regulating element 29. This eccentric makes it possible to modify the stiffness of the elastic blades 27 and consequently the amplitude of the rotation of the rake 21 and of the balance wheel 10. More precisely, the two pins 30 of this regulating element 29 can be moved, which makes it possible to regulate, within a certain margin, the distance between the elastic blade 27 and the axis of rotation 24 of the rake. This allows fine regulating of the rate of the watch. This fine regulating of the rate of the watch can also be done through a screw balance wheel, as represented in the various figures, or with inertia-block balance wheels.

[0067] In the embodiment illustrated by FIGS. 7 and 8, the return mechanism 25 is separated from the rake 21 and is not integral with the latter. In this realisation, the rake 21 pivots on its axis of rotation 24 and comprises a single arm 23 connecting the toothed sector 22 of the rake to its axis of rotation 24.

[0068] The return mechanism 25 also comprises two elastic blades 27, these blades being produced independently of the rake 21. These elastic blades are integral with a support 32 fixed to a plate of the timepiece movement. Each of the elastic blades 27 works together with one side of the arm 23 of the rake. When moving the rake in one direction, one of the elastic blades 27 leans against the corresponding side of the rake arm and deforms. This has the effect of allowing this elastic blade to store energy. The other elastic blade does not interact with the rake 21 so that only the stiffness of one blade intervenes and not of both.

[0069] At the end of the motion of the rake 21, the elastic blade 27 returns energy and pushes the rake in the opposite direction, as it has been explained above. The areas of contact between the elastic blades 27 and the arm 23 of the rake can be polished so as to minimize friction. The rake 21 and the elastic blades 27 being arranged in the same plane, these elastic blades do not undergo torsion, but only a bending which makes it possible to store and to return energy.

[0070] In the embodiment of FIG. 9, the elastic blades 27 are arranged on a movable support 33 whose position can be adjusted on the plate of the watch movement. This adjustment is possible by the fact that this mobile support 33 comprises a toothed bar 34 and the plate comprises a regulating pinion 35. The rotation of the regulating pinion 35 has the effect of moving the toothed bar 34 and thus the position of the elastic blades 27. This makes it possible to modify the distance between the axis of rotation 24 of the rake and the points of contact between the elastic blades 27 and the arm 23 of the rake. This modifies accordingly the force required to move the rake 21, which corresponds to an adjustment of the stiffness or of the visible stiffness of the elastic blades 27.

[0071] FIGS. 10 and 11 illustrate a variant of the return member 19 according to the invention, in which the rake 21, the arm 23 of the rake and the elastic blades 27 of the return mechanism are made in one piece. In this embodiment, as in the one described with reference to FIGS. 4 to 6, the timepiece comprises two pins 30 arranged so that the elastic blades 27 can lean against them and be deformed so as to store and return energy.

[0072] In this embodiment, the elastic blades 27 slide along the pins 30 and are not integral with them. There is thus a deformation in the form of bending of one blade at a time. There is neither simultaneous deformation of the two elastic blades, nor buckling, which would make the stiffness of the blades too great for real operation of the movement.

[0073] FIG. 10 illustrates the rake 21 in rest position and FIG. 11 illustrates the latter in working position. As can be seen in particular on FIG. 11, only one blade at a time works to store and return energy. Indeed, only the elastic blade interacting with the pin 30 is active. The other elastic blade 27, represented on the left on FIG. 11, does not interact with the corresponding pin 30 and therefore does not participate in the accumulation or in the return of energy, in this phase of the motion of the rake.

[0074] In the embodiments illustrated by FIGS. 12 to 15, the rake 21 is similar to the one of FIGS. 7 to 9. The elastic blades 27 of the return mechanism 25 are not rectilinear rods at rest, and form curves. An end zone of each of the elastic blades 27 leans against one side of the arm 23 of the rake 21 and operates according to the same principle as what has been explained with reference to FIGS. 7 to 9.

[0075] This realisation has the advantage of making it possible to increase the length of the elastic blades 27 and thus consequently to reduce their stiffness, however without the need to increase the size of the timepiece in which this return member will be housed. The blades illustrated by FIGS. 12 and 13 differ in their width and in the position of the contact between the elastic blades and the rake arm. The choice of the specific shape of the blades depends in particular on the space available in the movement.

[0076] In the embodiment illustrated by FIGS. 14 and 15, the elastic blades 27 form folds in the form of bellows. This embodiment is of interest because it makes it possible to produce blades of great length, without requiring a significant available space in the timepiece case. In this respect, it approaches the length of the spiral springs, without however having the relative disadvantages.

[0077] The embodiments of FIGS. 12 to 15 are also of interest because the position of the point of contact between the active spring blade 27 and the arm 23 of the rake moves with the motion of the rake 21. As can be seen in particular by comparing FIGS. 14 and 15, which respectively represent the rake 21 in rest position and in working position, when the rake 21 is in rest position or close to this position, the point of contact between one of the elastic blades 27 and the arm 23 of the rake is very close to the axis of rotation 24 of the rake. Therefore, the elastic blade 27 offers very little resistance to the rake 21, which allows a simple start of the movement, without risk of blocking. When the rake 21 pivots, as illustrated by FIG. 15, the shape of the elastic blades means that the point of contact between the active elastic blade 27 and the rake 21 moves in the direction of the toothed sector 22, opposite to the axis of rotation 24 of the rake. The force opposed by the elastic blade to the rake increases, which increases the energy that the elastic blade is able to store. In this way, the energy of the return mechanism 25 is not linear relative to the motion of the rake 21, and it is very weak when the rake 21 is close to its rest position. This allows not only an easy start of the movement, but also an optimal accumulation and return of energy.

[0078] In the embodiment of FIG. 16, the rake 21 comprises internal teeth. The return mechanism 25 is identical to the one of FIGS. 14 and 15. This is of interest because one part of the rake is located on the other side of the balance wheel shaft 11 relative to the axis of rotation 24 of the rake. This allows to save space which can be useful in a small watch case and/or if the space dedicated to the escapement is limited.

[0079] To allow the movement to start during raising and to avoid stop problems on the rest plane, it is judicious not to apply stress or weak stress on the arm 23 of the rake 21 when the latter is in its rest position, at dead centre. This can be done in several ways. According to one of the ways, the shape of the elastic blades 27 themselves is provided for this purpose, as has been explained with reference to FIGS. 14 and 15. According to another variant, for example illustrated by FIGS. 7 and 8, a slight clearance could be provided between the elastic blades 27 and the arm 23 of the rake when this rake is at dead centre. This clearance is visible in particular on FIG. 7a, which represents in a very enlarged way the zone of contact between the elastic blades 27 and the arm 23 of the rake as illustrated by FIG. 7. In this way, no force is applied to the rake by the return mechanism 25 when this rake is at dead centre. A force begins to be applied to the rake when it has begun to move.

[0080] According to another way, the timepiece movement comprises a regulating element 29, such as the eccentric pins 30 illustrated in FIGS. 5 and 6, making it possible to position the elastic blades 27 in a suitable position, which can be regulated and modified if necessary.

[0081] According to a preferred embodiment, stress may begin to be applied to the arm 23 of the rake 21 when the balance wheel 10 is pivoted by approximately 10°. Such a rotation allows to place one of the pallets of the lever on the impulse plane of one of the escapement teeth, which avoids blocking of the movement and allows it to start.

[0082] The rake 21 has been represented as comprising two arms 23 in FIGS. 4 to 6 and a single arm in the other figures. Particular shapes of elastic blades have been represented for each embodiment. Combinations of the different embodiments are also possible. For example it is possible to use elastic blades as illustrated by FIGS. 12 to 16, with a two-arm toothed rake as illustrated by FIGS. 4 and 6.

[0083] Likewise, regulating elements such as eccentrics or a mobile support can be added to the various embodiments illustrated.