Clockwork escapement, reset component for clockwork escapement, clockwork and clock with such a clockwork

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of watchmaking and in particular to portable mechanical watchmaking. Its object is the replacement of the spiral spring as a return member of the balance wheel by a component that is simpler to manufacture, which does not have the defects of the spiral and which can be adapted to existing escapement systems for portable watchmaking.

[0002] More particularly, the present invention relates to a timepiece movement escapement, comprising a balance, an escape wheel, an anchor and a balance return member. It also relates to a return member for a timepiece movement comprising an escapement provided with a balance, an escape wheel and an anchor.

[0003] The invention also relates to a timepiece movement comprising an escapement provided with a balance, an escape wheel, an anchor and a balance return member.

[0004] Finally, this invention relates to a timepiece comprising a movement, an escapement or a return organ as defined above. PRIOR ART

[0005] Fixed clocks, whether monumental, wall-mounted, or table-mounted, have, for centuries, provided sufficient precision thanks to the invention of the pendulum. This pendulum's precision is due to the force of gravity acting on the return organ to bring the pendulum back to its neutral position. Since the clock is fixed, it benefits from the force of gravity, which is invariable.

[0006] The first attempts at portable clockmaking were made with a flywheel escapement and the addition of a foliot as a return mechanism. As this system could not provide satisfactory precision, a substantial improvement was only achieved after the invention of the balance spring.

[0007] However, the spiral spring is far from being as satisfactory as the force of gravity, and its performance is far from invariable. Apart from its very delicate manufacture, the most important defect is its variation in vertical position, as well as the variation of its torque between the contraction and relaxation of turns, which in professional terms is called ascending angle and descending angle. Despite all the research, in its form and in its material, no satisfactory solution to its drawbacks has yet been found.

[0008] So, despite all the research on escapements, even on balance wheels or other components, their arrangements and functions, we have not managed to escape the straitjacket of the hairspring.

[0009] Several developments have sought to replace the balance spring in a watch movement. Among these, Swiss patent No. 34983 may be cited. In this patent, the watch movement comprises a toothed rack acting on a balance pinion. The rack has a split stem and pivots on an axis disposed at the end of the split stem opposite the teeth of the rack. The movement of the timepiece comprises a spring blade fixed to a plate at one of its ends and provided with a lug near its other end. The lug is designed to slide in the slot in the split stem of the rack. This rack, the split stem and the spring blade cooperate to form the return member of the balance.

[0010] In this embodiment, the elastic blade must be capable of storing energy when it is deformed by the movement of the rack. It must then release this energy to move the rack in the opposite direction, beyond the dead center or the rest position of the rack. The maintenance of the movement and the compensation of friction are done by the cooperation between an impulse plane of the escape wheel and the lifting of the anchor.

[0011] The embodiment described in the aforementioned patent has several problems. The elastic blade and the slotted rod are not in the same plane. The lug protrudes from the elastic blade so that it can be placed in the slot of the slotted rod. The movement of the lug in the slot generates a twisting of the elastic blade as well as friction, which involves significant energy losses.

[0012] Furthermore, the elastic blade must meet two contradictory constraints. On the one hand, its stiffness must be sufficiently high so that a sufficient amount of energy is stored during its deformation under the effect of the movement of the balance and restored when the elastic blade returns towards its rest position. This amount of energy must also compensate for losses linked to friction of the lug in the slot and to twists of the elastic blade.

[0013] On the other hand, the stiffness must be low enough so that the rake can move enough to allow an angular displacement of the pendulum of at least 300°.

[0014] An elastic blade that is too rigid would prevent a significant angular displacement of the rake because this elastic blade would tend to bring this rake back to its neutral position as soon as it had made a relatively small angular displacement. An elastic blade that is too weak would not allow sufficient energy to be stored to allow the pendulum to continue its movement.

[0015] Furthermore, if the spring blade is too rigid, the movement cannot start. Indeed, the movement can only start if a lever lift has reached an impulse plane of the escape wheel. This is not possible if the spring blade is too rigid.

[0016] With the system as described in the aforementioned patent, an existing elastic blade or one made with existing materials and technologies would not allow the principles of the invention to be implemented, its stiffness being too great to allow a sufficiently large movement of the balance.

[0017] Since the stiffness of a spring depends in particular on its useful length, one solution for reducing the stiffness of the elastic blade could be to lengthen it. A typical spiral spring has between 12 and 15 turns. In practice, a watch case such as a typical wristwatch does not accommodate an elastic blade long enough to obtain a functional return organ.

[0018] The invention described in this patent CH 34983 sought to solve certain problems of spiral springs by producing a symmetrical return member, which avoids the problems linked to the asymmetry of the spiral springs. However, the result obtained cannot be implemented in practice in a wristwatch type watch.

[0019] Swiss patent application No. 19698 also describes, in one embodiment, a rack acting on a balance pinion. As in the aforementioned patent CH 34983, the rack is connected to an elastic rod whose deformation is supposed to allow the rotation of the balance pinion.

[0020] The invention described in this patent suffers from the same problems as those described in the aforementioned patent so that it is not possible to put this invention into practice.

[0021] In order to replace the spiral spring and the disadvantages thereof, it would be advantageous to find a solution to provide a balance actuating member which is simpler to manufacture than the spiral, which is symmetrical, which allows the movement of the timepiece to start, whose size is compatible with use in a wristwatch of conventional size and which does not suffer from the disadvantages of the embodiments of the inventions described in the prior art.

[0022] Document WO2015 / 010797A1 presents a clockwork movement resonator comprising: a balance, a pinion mounted coaxially and integral with the balance, at least one moving part comprising teeth engaged with the pinion, and two spring members being blades and exerting a return force on the moving part, these two spring members being arranged symmetrically with respect to the axis of the intermediate mobile, so that in view of the influence of gravity on the spring members, they compensate each other. DESCRIPTION OF THE INVENTION

[0023] The disadvantages of the prior art return members are eliminated by the return member of the present invention.

[0024] The aim of this invention is to provide a return member which reacts in the same way in both directions of movement of the balance wheel, which is not disturbed in vertical positions and which is not as fragile and delicate in its handling as a spiral spring.

[0025] These aims are achieved by a clockwork escapement as defined in the preamble and characterized in that the balance is integral with a balance pinion, and in that the balance return member comprises a rack provided with a toothed sector arranged to cooperate with the balance pinion, this rack comprising an axis allowing its rotation between two extreme positions, called working positions, separated by a rest position; this return member further comprising a return mechanism comprising two springs arranged to urge the rack towards its rest position.

[0026] The aims of the invention are also achieved by a return member as defined in the preamble and characterized in that it comprises a rake provided with a toothed sector arranged to cooperate with a balance pinion, this rake comprising an axis allowing its rotation between two extreme positions, called working positions, separated by a rest position; and two springs arranged to urge the rake towards its rest position.

[0027] The aims of the invention are further achieved by a timepiece movement as defined in the preamble and characterized in that the balance is integral with a balance pinion, and in that the balance return member comprises a rack provided with a toothed sector arranged to cooperate with the balance pinion, this rack comprising an axis allowing its rotation between two extreme positions, called working positions, separated by a rest position, this return member further comprising a return mechanism comprising two springs arranged to urge the rack towards its rest position.

[0028] Finally, the aims of the invention are achieved by a timepiece comprising a movement, an escapement or a return organ as defined above.

[0029] According to the invention, unlike the spiral spring, the return member is not fixed to the balance wheel and its connection with the balance wheel is via mechanical gearing.

[0030] This return organ comprises a toothed part, hereinafter called a rack, and a return mechanism comprising two springs made in the form of two elastic blades. The increase in friction due to the gearing between the rack and the balance pinion is, according to the invention, compensated by the reduction in the disadvantages due to the spiral spring, its pinion, its index assembly as well as the defects described at the beginning of this presentation.

[0031] The escapement of the invention comprises a rack provided with a toothed sector cooperating with a balance pinion. It also comprises a return mechanism provided with two elastic blades. The rack pivots on its axis between two extreme positions, called working positions and corresponding to the maximum rotation of the balance. These two extreme points are separated by a rest position.

[0032] When the rack is moved out of its rest position, one of the elastic blades is deformed by the rack. This deformation has the effect of allowing the elastic blade to store energy. This energy is then used by the elastic blade to force the rack to move towards its rest position. Due to the configuration of the escapement and in particular the anchor, the energy supplied to the rack allows it to move beyond its rest position. When it has moved beyond this rest position, the elastic blade that supplied it with energy no longer interacts with the rack. The other elastic blade in turn interacts to store and then release energy.

[0033] According to the invention, the return member has a symmetry with respect to a plane passing through an axis of rotation of the balance wheel. Due to this symmetry, the forces acting when the balance wheel moves in one direction of rotation are the same as those acting when the balance wheel moves in the other direction of rotation. One of the disadvantages due to the asymmetry of the balance spring is thus eliminated.

[0034] The return member of the invention is formed of a return mechanism comprising two springs made in the form of two elastic blades or spring blades acting on the rack. These elastic blades can be configured and placed in such a way that the rack can move slightly angularly before one of the elastic blades acts on it to return it to its rest position. This allows the watch movement to start and avoids the problem of stopping on the resting plane. The fact of using two elastic blades independent of each other and never working simultaneously makes it possible to divide the stiffness of the return mechanism by two, which makes it possible to obtain blades of a length sufficiently short to be able to be placed in a conventional-sized watch case. This makes it possible in particular to avoid the problems of the return members described in patents CH 34983 and CH 19698.

[0035] In the return member of the invention, the two elastic blades are independent of each other. Therefore, when one of the blades is deformed so as to store energy or to restore it, the other elastic blade is inactive and does not interact with the rake. This avoids problems linked to elastic blades that are too rigid, which could arise in the case where two elastic blades act simultaneously on the rake.

[0036] The rack is formed from a sector of a toothed wheel that could typically have between 80 and 160 teeth. Assuming that the balance wheel moves through a 330° amplitude and that the balance pinion has 10 teeth, the angular displacement would be 37.125° for a rack corresponding to an 80-tooth wheel and 18.5625° for a rack corresponding to a 160-tooth wheel. The small angular displacement of the rack can be managed by the return mechanism while still allowing for a large angular displacement of the balance wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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: there Figure 1 is a top view of a classic Swiss lever escapement, without a hairspring; the Figure 2 is a side view of the exhaust of the Figure 1 ; there Figure 3is a side view of the exhaust of the Figures 1 and 2 , comprising a balance shaft fitted with a pinion; the Figure 4 is a top view of part of the exhaust of the figures 1 to 3 , comprising a return member according to a first embodiment of the present invention, in a rest position; Figure 5 illustrates the recall organ of the Figure 4 , in a resting position; the Figure 6 illustrates the recall organ of the Figure 4 , in a working position; the Figure 7 is a top view of a variant of the return member of the invention, in a rest position; Figure 7a is an enlarged view of part of the Figure 7 ; there figure 8 is a top view of the return organ of the Figure 7 , in a working position; the Figure 9 illustrates a recall organ similar to that of the Figure 6 , in which an adjustment of the position of the elastic blades can be carried out; the Figure 10represents a variant of the return member according to the invention, in a rest position; the Figure 11 is a view of the recall organ of the Figure 10 , in a working position; the figures 12 to 14 illustrate other variants of return members according to the invention, in the rest position; the Figure 15 represents the recall organ of the figure 14 , in working position; and the figure 16 represents a return organ with an internally toothed rake and a return mechanism identical to that of the Figures 14 and 15 . METHOD OF CARRYING OUT THE INVENTION

[0038] The invention relates in particular to a clockwork movement escapement. In the illustrated embodiments, the escapement comprises a conventional part and a novel part. The conventional part is shown in the figures 1 to 3by a part of a Swiss anchor escapement. This escapement comprises a balance 10 pivoting on a balance staff 11, an anchor 12 pivoting on an anchor staff 13 and an escape wheel 14 pivoting on an escape wheel staff 15. The anchor 12 also conventionally comprises, in particular, a fork 16 actuated by the balance 10 and two lifts 17 acting on teeth 18 of the escape wheel 14. Unlike conventional escapements, this escapement does not comprise a balance spring. It should be noted that the Swiss anchor escapement has been shown 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 serves as a regulating member.

[0039] The new part includes a return member 19 replacing the spiral spring in its function.

[0040] The return organ according to the invention can be integrated into an existing escapement or be part of an escapement developed specifically for this movement.

[0041] With particular reference to the Figure 3 , the balance wheel 10 used in the present invention comprises a balance wheel pinion 20 secured to the balance wheel shaft 11.

[0042] The return member 19 according to the present invention comprises a rack 21 comprising a toothed sector 22 and one or two arms 23. The rack 21 pivots around a rack axis 24 secured to a plate (not shown) of the clockwork movement. This rack can move on either side of its rest position, between two extreme working positions, in which the balance 10 has made a maximum movement, in the clockwise direction or in the counterclockwise direction.

[0043] The return member 19 further comprises a return mechanism 25 comprising two springs 26 whose operation is described below. These springs 26 are formed of two elastic blades 27 in the illustrated embodiments.

[0044] In the embodiment illustrated by the figures 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 meet near the axis 24 of rotation of the rake.

[0045] This rake 21 further comprises a rod 28 having one end close to the axis 24 of the rake and the other end secured to the elastic blades 27.

[0046] The return member 19 can be placed on a plate of a timepiece which comprises two pins 30 arranged so that the elastic blades 27 can bear against these pins depending on the position of the rack 21.

[0047] In this embodiment, the rake 21, the arms 23, the rod 28 and the elastic blades 27 are integral and are made from a single piece.

[0048] THE Figures 4 and 5 illustrate the rake 21 in the rest position. The Figure 6 illustrates the rake 21 in working position.

[0049] When the pendulum 10 is pivoted in one direction, in a working position as illustrated for example by the Figure 6 , the balance pinion 20 acts on the toothed sector 22 of the rack 21 to pivot the latter 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, nor with the other pin 30 so that it does not oppose the rotation of the rack 21 or the balance 10.

[0050] When the stress exerted by the elastic blade 27 is sufficient, after a certain angular displacement of the rake 21 and therefore of the balance 10, the blade restores energy and pivots the rake in the other direction of rotation. This causes the balance wheel to rotate via the balance wheel pinion 20. Conventionally, the balance wheel 10 acts on the anchor 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 lifts 17 of the anchor 12 so as to provide energy to this anchor 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 rack 21 to rotate on its axis 24 and makes it possible to load the other elastic blade 27 of the return mechanism 25.

[0051] This reciprocating motion is similar to that generated by a hairspring. However, unlike the hairspring, the elastic blades 27 are symmetrical to each other when the rack is in the rest position, which implies that there is no difference in operation when the balance wheel 10 pivots clockwise or counterclockwise.

[0052] The pins 30 can be mounted on an eccentric and thus form an adjustment 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 rack 21 and the balance 10. More precisely, the two pins 30 of this adjustment element 29 can be moved, which makes it possible to adjust, within a certain margin, the distance between the elastic blade 27 and the axis of rotation 24 of the rack. This allows fine adjustment of the rate of the watch. This fine adjustment of the rate of the watch can also be done through a screw balance, as shown in the various figures, or with balances with weights.

[0053] In the embodiment illustrated by the Figures 7 and 8, the return mechanism 25 is separate from the rake 21 and is not integral with the latter. In this embodiment, 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.

[0054] The return mechanism 25 also comprises two elastic blades 27, these blades being produced independently of the rack 21. These elastic blades are integral with a support 32 fixed to a plate of the movement of the timepiece. Each of the elastic blades 27 cooperates with one side of the arm 23 of the rack. When the rack is moved in one direction, one of the elastic blades 27 bears against the corresponding side of the arm of the rack and deforms. This has the effect of allowing this elastic blade to store energy. The other elastic blade does not interact with the rack 21 so that only the stiffness of one blade and not both intervenes.

[0055] At the end of the movement of the rake 21, the elastic blade 27 restores energy and pushes the rake in the opposite direction, as explained previously. The contact areas 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 allows energy to be stored and restored.

[0056] In the embodiment of the Figure 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 because this movable support 33 comprises a rack 34 and the plate comprises an adjustment pinion 35. The rotation of the adjustment pinion 35 has the effect of moving the rack 34 and therefore the position of the elastic blades 27. This makes it possible to modify the distance between the axis of rotation 24 of the rack and the points of contact between the elastic blades 27 and the arm 23 of the rack. This consequently modifies the force necessary for moving the rack 21, which corresponds to an adjustment of the stiffness or apparent stiffness of the elastic blades 27.

[0057] THE Figures 10 and 11illustrate 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 a single piece. In this embodiment, as in that described with reference to figures 4 to 6 , the timepiece comprises two pins 30 arranged so that the elastic blades 27 can bear against them and be deformed so as to store and restore energy.

[0058] 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.

[0059] There Figure 10 illustrates the rake 21 in the rest position and the Figure 11illustrates the latter in working position. As can be seen in particular on the Figure 11 , only one blade at a time works to store and restore energy. In fact, only the elastic blade interacting with the pin 30 is active. The other elastic blade 27, shown on the left in the Figure 11 , does not interact with the corresponding pin 30 and therefore does not participate in the accumulation or restitution of energy, in this phase of the movement of the rake.

[0060] In the embodiments illustrated by the figures 12 to 15 , rake 21 is similar to that of the figures 7 to 9 . The elastic blades 27 of the return mechanism 25 are not straight rods at rest, but form curves. An end zone of each of the elastic blades 27 bears against one side of the arm 23 of the rake 21 and operates according to the same principle as that explained with reference to figures 7 to 9 .

[0061] This embodiment has the advantage of allowing the length of the elastic blades 27 to be increased and therefore their stiffness to be reduced, without however having to increase the size of the timepiece in which this return organ will be housed. The blades illustrated by the Figures 12 and 13 They are differentiated by their width and by the position of 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.

[0062] In the embodiment illustrated by the Figures 14 and 15 , the elastic blades 27 form folds in the form of bellows. This embodiment is interesting because it allows blades of great length to be produced, without requiring a large amount of available space in the case of the timepiece. As such, it approaches the length of the spiral springs, without however having the drawbacks thereof.

[0063] The methods of realization of the figures 12 to 15 are also interesting because the position of the contact point between the active elastic blade 27 and the arm 23 of the rake moves with the movement of the rake 21. As can be seen in particular by comparing the Figures 14 and 15 , which respectively represent the rake 21 in the rest position and in the working position, when the rake 21 is in the 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. As a result, 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 the Figure 15, the shape of the elastic blades implies that the point of contact between the active elastic blade 27 and the rake 21 moves towards the toothed sector 22, opposite 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 with respect to the movement of the rake 21, but is very low 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 restitution of energy.

[0064] In the embodiment of the figure 16 , the rake 21 comprises an internal toothing. The return mechanism 25 is identical to that of the Figures 14 and 15This is interesting because part of the rack is on the other side of the balance shaft 11 from the rack rotation axis 24. This saves space which can be useful in a small watch case and / or if the space dedicated to the escapement is reduced.

[0065] To allow the movement to start upon reassembly and to avoid problems with stopping on the rest plane, it is advisable to apply no stress or a low stress to the arm 23 of the rake 21 when the latter is in its rest position, in neutral. This can be done in several ways. In one way, the shape of the elastic blades 27 themselves is provided for this purpose, as has been explained with reference to Figures 14 and 15 . According to another variant, for example illustrated by the Figures 7 and 8, a slight play could be expected between the elastic blades 27 and the arm 23 of the rake when this rake is in neutral. This play is visible in particular on the Figure 7a , which represents in a very enlarged way, the contact zone between the elastic blades 27 and the arm 23 of the rake as illustrated by the Figure 7 . In this way, no force is applied to the rake by the return mechanism 25 when this rake is in neutral. A force begins to be applied to the rake when it has started its movement.

[0066] Alternatively, the timepiece movement includes an adjustment element 29, such as the eccentric pins 30 illustrated by the Figures 5 and 6 , allowing the elastic blades 27 to be positioned in a suitable position, which can be adjusted and modified if necessary.

[0067] According to a preferred embodiment, a stress can begin to be applied to the arm 23 of the rack 21 when the balance wheel 10 is pivoted by approximately 10°. Such a rotation allows one of the levers of the anchor to be positioned on the impulse plane of one of the teeth of the escapement, which prevents the movement from being blocked and allows it to start.

[0068] The rake 21 has been shown as having two arms 23 in the figures 4 to 6 and a single arm in the other figures. Particular shapes of elastic blades have been shown for each embodiment. Combinations of the different embodiments are also possible, without departing from the scope defined by the appended claim 1. It is for example possible to use elastic blades as illustrated by the figures 12 to 16 , with a two-armed toothed rake as illustrated by the Figures 4 and 6 .

[0069] Likewise, adjustment elements such as eccentrics or a movable support can be added to the various embodiments illustrated.

Claims

1. Clockwork movement escapement, comprising a balance wheel (10) pivoting on an axis of rotation (11) of the balance wheel, an escape wheel (14), a lever (12) and a balance wheel return member (19), escapement in which the balance wheel (10) is integral with a balance wheel pinion (20); the balance wheel return member (19) comprises: ∘ a rake (21) provided with a toothed sector (22) arranged to work together with the balance wheel pinion (20), this rake (21) comprising an axis (24) allowing its rotation between two extreme positions, called working positions, separated by a rest position; and ∘ a return mechanism (25) comprising two springs (26) arranged to press the rake (21) towards its rest position, these springs (26) comprising elastic blades (27) arranged to store energy and return energy to the rake (21); and characterized in that only one of the elastic blades (27) stores and returns energy at the same time.

2. Clockwork movement escapement according to claim 1, characterized in that, when the rake is in its rest position, the springs (26) are arranged symmetrically with respect to a plane passing through the axis of rotation (11) of the balance wheel and the axis of rotation (24) of the rake.

3. Return member for a timepiece movement comprising an escapement provided with a balance wheel (10), with an escape wheel (14) and with a lever (12), this return member (19) being characterized: ∘ in that it comprises a rake (21) provided with a toothed sector (22) arranged to work together with a balance wheel pinion (20), this rake (21) comprising an axis (24) allowing its rotation between two extreme positions, called working positions, separated by a rest position; ∘ in that it comprises two springs (26) arranged to press the rake (21) towards its rest position, these springs (26) comprising elastic blades (27) arranged to store energy and return energy to the rake (21); and ∘ in that only one of the elastic blades (27) stores and returns energy at the same time.

4. Return member according to claim 3, characterized in that, when the rake is in its rest position, the springs (26) are arranged symmetrically with respect to a plane passing through an axis of rotation (11) of the balance wheel and through the axis of rotation (24) of the rake.

5. Return member according to claim 3, characterized in that the rake (21) has internal teeth.

6. Return member according to claim 3, characterized in that the elastic blades (27) are integral with the toothed sector.

7. Return member according to claim 3, characterized in that the elastic blades (27) are arranged to lean against an arm (23) of the rake (21).

8. Timepiece movement comprising an escapement provided with a balance wheel (10), with an escape wheel (14), with a lever (12) and with a balance wheel return member (19), this movement being characterized: • in that the balance wheel (10) is integral with a balance wheel pinion (20); • in that the balance wheel return member (19) comprises: ∘ a rake (21) provided with a toothed sector (22) arranged to work together with the balance wheel pinion (20), this rake (21) comprising an axis (24) allowing its rotation between two extreme positions, called working positions, separated by a rest position; and ∘ a return mechanism (25) comprising two springs (26) arranged to press the rake (21) towards its rest position, these springs (26) comprising elastic blades (27) arranged to store energy and return energy to the rake (21); and • in that only one of the elastic blades (27) stores and returns energy at the same time.

9. Timepiece movement according to claim 8, characterized in that this movement comprises at least two pins with which said elastic blades interact alternately during the movement of the rake around its axis of rotation (24).

10. Timepiece movement according to claim 8, characterized in that it comprises a regulation element (29) of the escapement.

11. Timepiece movement according to claim 10, characterized in that the regulation element (29) of the escapement comprises at least two pins (30) movable on a plate of the movement and interacting with said springs (26).

12. Timepiece comprising a movement according to any one of claims 8 to 11.