EP2166419A1 - Clock timepiece movement comprising a constant-force device - Google Patents

Abstract

The movement has a kinematic chain connecting a barrel (1) to an end of a balance-spring, where the chain is formed of a driving gear (4), a pinion (5) and a wheel (6). Another kinematic chain connects a time base to another end of the balance-spring, where the other chain is formed of a second mobile (13) and an escapement wheel (16). Each chain includes a wheel mobile (9) with an adjustment body (20). The body includes a peripheral tooth (41) defining a support surface, where the tooth acts on the surface to turn the body.

Description

Technical area

The present invention relates to a watch movement comprising a constant-force device, comprising a spiral spring, and a train having a first kinematic chain arranged to connect a main energy source to a first end of the spiral spring, and a second chain kinematic for connecting a time base to a second end of the spiral spring.

State of the art

Many watch movements with constant force devices, of the type mentioned above, have been described for a long time.

For example, the patent US 1,237,216 , issued in 1917, describes a watch movement comprising a primary cylinder spring, large power reserve, and a secondary cylinder spring, lower power reserve, the latter having the advantage of delivering a substantially constant torque while at the same time. along its development. Thus, the secondary spring is used to power a time base in energy while the primary spring periodically recharges the secondary spring, without the variations in the delivered torque that it presents as a function of its state of charge do not disturb walking the time base. A control mechanism driven from the motion train controls the periodic release of an end of the secondary spring to allow recharging of the secondary spring.

A few decades later, movements of this type have been adapted for use in pocket watches or wristwatches.

These small movements are complex and therefore difficult to assemble. In particular, the amplitude of the oscillations of the mechanical oscillator, critical for the precision of the movement, is difficult to adjust, especially as it depends on the state of charge of the secondary spring. Thus, the adjustment of the gait, which is delicate, must be performed by the watch manufacturer at the time of assembly of the movement, in particular by adjusting the initial state of charge of the secondary spring. When the operation is to be carried out later, as part of the after-sales service, it presents again the same complexity.

The patent CH 19839 , issued August 4, 1899, had already presented this problem and proposed a solution. It was intended to provide a plurality of holes the wheel carrying one end of the secondary spring. Thus, by arranging the end of the secondary spring in one hole or another, it was possible to vary its state of charge.

However, adjustment of the state of charge of the secondary spring by means of this mechanism remains perilous, especially when the movement works.

After several decades of neglect at the end of the ^twentieth century, the constant force devices seem again to be of interest for prestigious watchmaking factories.

For example, the patent US 7,293,912 B2 was issued on 13 November 2007 on behalf of Lange Uhren GmbH. However, it is noteworthy that this constant-force device, although of complex construction, does not provide a means for easy adjustment of the state of charge of the secondary spring.

Disclosure of the invention

The main object of the present invention is to propose a watch movement comprising a constant-force device of simple construction, limiting as much as possible the disturbances related to its operation which could influence the movement of the motion time base and whose state of being. load of the secondary spring can be adjusted accurately and simply.

For this purpose, the mechanism according to the invention has the characteristics described above and is characterized in that one or the other of the first and second kinematic chains comprises an adjustment wheel comprising first and second connected members. to one another by a friction such that a rotation of one leads to the other during the running operation of the watch movement. In addition, one of these members is an adjustment member having at least one bearing surface arranged in such a way that it is possible to act on it to rotate the adjustment member without rotating the other member, due to the friction, in order to adjust the state of charge of the spiral spring.

Thanks to the features of the invention mentioned above, the watchmaker can intervene on the movement to make an adjustment of the state of charge of the spiral spring relatively easily, even when the movement works. Indeed, unlike the known mechanisms of the state of the art, it is not necessary to disassemble any element of the movement whatsoever to adjust the state of charge of the spiral spring.

Preferably, the watch movement according to the invention is such that the adjustment wheel comprises
a main shaft kinematically connected to the main energy source,
a stop wheel integral with this shaft and carrying a fastening element integral with the first end of the spiral spring,
the adjustment member, having the form of a shaft mounted coaxially and free to rotate relative to the main shaft and having a fastening element of the second end of the spiral spring,
the second member, in the form of a drive wheel frictionally mounted on the adjustment member and kinematically connected to the time base.

Preferably, the adjustment mobile can perform the moving average function of the movement.

Furthermore, it is advantageously provided that the movement comprises a stop device arranged to lock the stop wheel in a predefined angular position and to release it periodically in order to allow a spring-spiral spring to be recharged from the spring source. main energy, according to a predefined amplitude, via the main shaft and the stop wheel.

Furthermore, the adjustment member preferably has a circular periphery provided with a knurling or toothing forming the bearing surface, while the movement may comprise, in addition, a control mobile adjacent to the mobile of adjustment and comprising a pinion gear capable of cooperating with this bearing surface.

Advantageously, the toothed pinion is movable in translation between a first rest position, in which it is disengaged from the bearing surface, and a second adjustment position in which it meshes with the bearing surface.

In addition, for the sake of simplifying interventions on the state of charge of the spiral spring, the control wheel is preferably provided with at least one slot adapted to cooperate with a tool for driving the toothed pinion in rotation.

Brief description of the drawings

Other features and advantages of the present invention will appear more clearly on reading the detailed description of a preferred embodiment which follows, made with reference to the accompanying drawings given by way of non-limiting examples and in which:

- the figure 1 represents a simplified perspective view of a general embodiment of a watch movement comprising a constant-force device according to the invention;

- the figure 2 represents a simplified top plan view of the watch movement of the figure 1 ;

- the figure 3 represents a simplified sectional view of the watch movement according to the plane III-III of the figure 2 ;

- the figure 4 represents a simplified sectional view of a construction detail of the figure 3 , following the same section plane, and

- the Figures 5a and 5b represent simplified sectional views of the watch movement according to the IV-IV plane of the figure 2 in respective first and second configurations.

Mode (s) of realization of the invention

The structure and general operation of a preferred embodiment of the present invention will be discussed in connection with the figures 1 , 2 and 3 , representing the movement respectively in perspective, in plan and in section. Only the elements contributing to the understanding of the invention are illustrated for the sake of clarity. Some elements of the figure 2 are partially broken away to make visible other elements superimposed on them.

A watch movement consisting essentially of conventional constituent bodies has been illustrated on the Figures 1 to 3 , in particular a barrel 1 housing a barrel spring (not visible) and intended to feed the mechanical oscillations of a time base of which only the escape wheel 2 has been shown. The energy of the mainspring is transmitted via a finishing gear comprising a center wheel 4 whose pinion 5 is engaged with the toothing of the barrel drum and whose wheel 6 is engaged with the pinion. 8 of a moving average 9. The wheel 10 of the average mobile is in turn engaged with a pinion 12 of a first mobile seconds 13 whose wheel 14 is in engagement with the exhaust pinion 16.

Furthermore, the watch movement according to the present invention comprises a constant force device for transmitting a constant force to the time base from the force it receives from the mainspring which varies significantly according to the arming of the latter.

More specifically, the constant force device comprises in particular a secondary spring 18 preferably having the shape of a spiral spring. It is mounted on the mobile of average 9 with a first of its ends, internal, integral with an adjustment member 20, whose operation will be described later, mounted free to rotate on the shaft of the mobile average 9 and carrying the wheel of average 10. The second end, external, of the spiral spring 18 is secured to a stop wheel 22 via a stud 23, the stop wheel being integral in rotation with the average mobile tree 9.

The constant-force device also comprises a second second wheel 24 whose wheel 25 meshes with the wheel 14 of the first seconds wheel 13, in a 1/1 ratio by way of nonlimiting illustration. The shaft of the second seconds mobile 24 carries a cam 26 with five bumps 28, integral with the rotating shaft. Thus, the cam 26 here performs a turn on itself in sixty seconds.

The cam 26 cooperates with a first fork 30 of a control anchor 31 pivotally mounted on a frame member of the movement (not visible) between two extreme positions.

The control anchor 31 comprises a second fork 32 arranged to cooperate with sawtooth teeth of the stop wheel 22. The second fork carries two pallets 34 and 35 arranged in such a way that, when the anchor pivots, one of the pallets being in contact with the toothing of the stop wheel 22, this pallet is disengaged from the toothing thus releasing the stop wheel which rotates here by twelve degrees (because the toothing has thirty teeth by way of non-limiting illustration) before another tooth abuts on the other pallet which, meanwhile, has positioned itself within reach of the toothing of the stopping wheel 22. As a result, the pallets ensure the locking of the stopwheel alternating, the latter advancing one step each time from one pallet to another.

It will be noted that the period of the alternations can also be adjusted by the choice of the shape of the cam 26, in particular the number of its bumps 28. In the case shown, each complete revolution of the cam 26 on itself causes ten pivoting of the anchor 31. In other words, the stop wheel 22 is released every six seconds.

The operation of the watch movement with constant force device which has just been described is described below.

Based on the principle that the spiral spring 18 has a non-zero state of load, the mechanical oscillator (a conventional balance spring, for example) being in oscillation mode, the spiral spring transmits a portion of its mechanical energy to the mechanical oscillator via the average wheel 10, the first seconds mobile 13, the exhaust pinion 16 and the escape wheel 2.

After six seconds of operation, the anchor 31 pivots under the effect of its cooperation with the cam 26 and releases the stop wheel 22, secured to the shaft of the average mobile 9, the latter being kept under tension by the barrel spring, via the center wheel 4. The stop wheel 22 then rotates twelve degrees, as explained above, driving with it the bolt 23 and therefore the outer end of the spring- spiral 18 (in the direction of the arrow indicated on the figure 2 ). The latter is thus recharged every six seconds by a relative displacement between its inner ends - fixed at the release of the stop wheel 22 - and external at an angle of twelve degrees.

Of course, the gears of the gear train are preferably chosen such that the average wheel 10 travels at an angle of twelve degrees during the six seconds separating two successive loads spiral spring 18, that is to say say that this wheel performs a complete turn on itself in three minutes. Thanks to these characteristics, the spiral spring 18 accumulates each time a quantity of energy from the mainspring corresponding to the spring that it transmitted to the mechanical oscillator of the movement during the previous six seconds.

This value of six seconds is indicative and the person skilled in the art will not encounter any particular difficulty in adapting the present teaching to his own needs, it being understood that the condition to be respected here, in order to ensure optimum operation of the device, is an amplitude of relative displacement between the two ends of the spiral spring such that the torque that the latter transmits to the mechanical oscillator is substantially constant.

As mentioned earlier in this paper, the amplitude of the oscillations of the mechanical oscillator, which is critical for the precision of the movement, is difficult to adjust, especially as it depends on the state of charge of the secondary spring. in a movement of the type comprising a constant force device. Thus, the movement according to the present invention proposes a mechanism for adjusting the state of charge of the secondary spring, easy to access and use, which will now be described in connection with the figures 4 , 5a and 5b .

The figure 4 represents the average mobile 9 according to the invention in a cross-sectional view taken along the same sectional plane as the figure 3 , namely according to plan III-III of the figure 2 .

It is clearer from the figure 4 that, as mentioned above, the stop wheel 22 is rotationally fixed to the shaft of the average mobile 9, formed in one piece with the pinion of average 8. The adjustment member 20 carrying the inner end the spring-spiral 18 is mounted free on the shaft of the average mobile 9 and carries the average wheel 10.

Thus, during the current operation of the watch movement between two successive loads of the spiral spring 18, the latter acts on the adjustment member 20 by its inner end, its outer end being held fixed by the stop wheel 22, for rotate the wheel of average 10 and maintain oscillations of the mechanical oscillator.

The state of charge of the spiral spring 18 can be adjusted by changing the relative angular positions of its two ends at a given moment.

As a result, the Applicant has had the idea of providing friction at the level of the connection between the adjustment member 20 and the average wheel 10. This friction is achieved in such a way that the adjustment member causes the average wheel during the running operation of the movement, while allowing to turn the adjustment member on itself when the average wheel is held fixed by the exhaust.

A rotation of the adjustment member clockwise on the view of the figure 2 thus causes a decrease in the tension of the spiral spring 18 while a rotation in the counterclockwise direction causes an increase in its tension.

To facilitate this manipulation, it is intended to make the adjustment member in the form of a shaft integral with a board 40 provided with a peripheral toothing 41, defining a bearing surface on which it is possible to act to turn the adjustment member on itself more easily.

In addition, a control mobile 42 is also provided in a position adjacent to that of the average mobile 9, the latter having a pinion toothed 44 arranged to cooperate with the toothing 41 of the adjustment member to rotate the latter.

Preferably, the pinion gear 44 is not in permanent engagement with the adjustment member to limit the friction losses of the watch movement, as is more clearly apparent from the Figures 5a and 5b .

The control mobile 42 is pivotally mounted and free in translation on a fixed foot 46 on an element of the frame 47 of the movement, such as the plate, the foot being disposed inside a hollow shaft of the control mobile.

In addition, a helical spring 48 is disposed between the control mobile and the frame member 47 tending to maintain the control mobile in a remote position with reference to the frame. In this position, represented on the figure 5a the toothed gear 44 is not engaged with the toothing 41 of the adjustment member 20.

When a pressure is applied on the control wheel 42, in the direction of the frame, the spring 48 is compressed and the toothed pinion 44 is placed within reach of the toothing 41 with which it meshes, as shown in FIG. figure 5b . A rotation of the control wheel 42 in this position then causes a rotation of the adjustment member 20, ie a change in the state of charge of the spiral spring 18.

Note that the control mobile 42 is advantageously provided with a slot 50 adapted to manipulation with a tool, such as a screwdriver, to further facilitate the adjustment of the state of charge of the spring- spiral 18 and therefore the amplitude of the oscillations of the mechanical oscillator of the watch movement.

Moreover, the watch movement according to the present invention further comprises a safety device to prevent inadvertent discharge of the spiral spring 18, in particular when the mainspring is discharged almost completely to the point of no longer having sufficient energy to recharge it. In this case, when no particular precaution is taken, it is possible that the spiral spring is discharged almost completely while continuing to feed the oscillations of the mechanical oscillator once the barrel spring is too discharged to be able to recharge it. It is then necessary to access the movement to reset the spiral spring 18 with a suitable tension to ensure a good accuracy of movement, which is very restrictive. To avoid this situation, the user of a watch equipped with such a mechanism must ensure that the mainspring is never fully discharged.

Alternatively, the Applicant has developed a safety device to overcome this problem.

For this purpose, the average wheel 10 has a particular shape, visible on the figure 2 through the adjustment member 20, represented in transparency: the hub and the serge of the average wheel are connected to one another by means of double arms 100 whose function is to ensure the connection by friction with the shaft of the adjustment member. It emerges figures 2 and 3 that the serge of the wheel of medium 10 also carries an addition of material 101 arranged in the plane of the serge and having a housing 102 inside which is disposed the peak 23 carrying the outer end of the spiral spring 18. The housing 102 is arranged such that it has an angular aperture substantially equal to or slightly greater than the stroke made by the pin when the stop wheel 22 or the average wheel 10 rotates twelve degrees. The housing 102 thus defines stops to movements of the piton in one direction and the other.

During the current operation of the movement, the peak 23 is close to a first edge of the housing 102 when the spiral spring 18 has just been reloaded, while the average wheel 10 runs for the next six seconds, such that the peak 23 is close to the other edge of the housing 102 after six seconds. If at the moment of the next charge the barrel spring no longer has enough energy to recharge the mainspring, the bolt 23 does not return towards the first edge and thus quickly forms a stop for the edge of the housing located at side of it, blocking the rotational motion of the average wheel, which causes a stop of the movement, then, gradually a stop oscillations of the mechanical oscillator.

Thanks to these characteristics, the spiral spring 18 still retains its initial state of charge, namely that which has been attributed to it during the adjustment of the movement by the manufacturer, relieving the user of the corresponding watch which is not forced to monitor the state of charge of the mainspring as in the case of movements of the state of the art.

Alternatively, it is also possible to provide that the stud 23 carrying the outer end of the spiral spring 18 is disposed directly between two arms 100 of the same pair, the latter thus forming stops to the movements of the pin in one direction and in the other. In this case, the spacing between the two arms of a pair is such that it is substantially equal to or slightly greater than the stroke made by the pin when the stop wheel 22 or the average wheel 10 rotates twelve degrees.

The foregoing description attempts to describe a particular embodiment by way of non-limiting illustration and the invention is not limited to the implementation of certain particular features which have just been described, for example the shape of the constituent organs of the constant force device or their locations. Indeed, the location of the constant force device is preferred on the average mobile, the Applicant having found that such a location makes it possible to limit the output torque constraints of the barrel applied to the device, while having a negligible disturbing effect on the operation of the mechanical oscillator. However, the implementation of the invention is not limited to such a provision and the skilled person can adapt the present teaching to his own needs without departing from the scope of the invention.

The period separating two successive loads of the spiral spring may also be modified without departing from the scope of the invention, to be for example equal to ten, twelve or even twenty seconds.

Furthermore, it should be noted that the principle of the present invention is not limited to a frictional implementation at the location indicated in the description. Indeed, the invention more generally relates to a watch movement comprising
a constant force device, comprising a spiral spring, and
a gear train having a first drive train arranged to connect a main power source to a first end of the hairspring spring, and a second drive train to connect a time base to a second end of the hairspring spring,
one or the other of the first and second kinematic chains comprising an adjustment wheel comprising first and second members connected to one another by a friction such that a rotation of one causes the other during the current operation of the watch movement,
one of these members being an adjustment member having at least one bearing surface arranged in such a way that it is possible to act on it to rotate the adjustment member without rotating the other member , because of the friction, in order to adjust the state of charge of the spiral spring.

Thus, it is possible to provide that the average wheel 10 is rigidly connected to the adjustment member 20, which would then no longer be an adjustment member, a friction being provided alternately between the wheel 14 of the first mobile of seconds 13 and the pinion 12 of this mobile. In this case, the state of charge of the spiral spring could be adjusted by action on the pinion 12 of the first seconds mobile 13, when the wheel 14 is held fixed by the exhaust.

Similarly, it is possible to arrange the stop wheel 22 on the center wheel 4, making it integral with the shaft, thus the center pinion 5. In this case, the center wheel 6 can be mounted friction on the shaft and be actuated to adjust the state of charge of the spiral spring 18. Specific additional wheels may also be provided alternatively.

The invention is also not limited to the particular embodiment described with regard to the bearing surface for actuating the adjustment member. It is of course conceivable to surface adapted to cooperate with a tool directly on the adjustment member 20, for example, without departing from the scope of the invention.

Claims (14)

Watch movement with
a constant force device comprising a spiral spring (18), and
a train having a first drive train (4, 5, 6, 8, 22) arranged to connect a main power source (1) to a first end of said hairspring, and a second drive train (10, 12, 13). , 14, 16) for connecting a time base to a second end of said hairspring,
characterized in that one or the other of said first and second kinematic chains comprises an adjustment wheel (9) comprising first and second members (10, 20) connected to each other by friction such that a rotation of one drives the other during the running operation of the watch movement, and
in that one of said members is an adjusting member (20) having at least one bearing surface (41) arranged in such a manner that it is possible to act on it to rotate said adjustment member without rotating the other member (10), because of said friction, to adjust the state of charge of said springs. Clock movement according to claim 1, characterized in that said sprung spring (18) is carried by said adjustment wheel (9), one of its ends being integral with said adjustment member (20). Clock movement according to claim 2, characterized in that said adjustment wheel (9) comprises
a main shaft (8) kinematically connected to said main energy source (1),
a stop wheel (22) rotationally fixed to said shaft and carrying a fastening element (23) integral with said first end of said spiral spring, said adjustment member (20) having the shape of a coaxial mounted shaft and free in rotation with respect to said main shaft and having an attachment element of the second end of said spiral spring,
said second member (10) having the form of a drive wheel frictionally mounted on said adjustment member and kinematically connected to said time base. Clock movement according to claim 3, characterized in that said adjustment wheel is a moving average (9), said main shaft being a medium shaft integrally carrying a pinion (8) cinematically connected to said power source main (1) and said second member being a wheel of average (10) arranged in engagement with a mobile seconds (12), itself engaged with said time base. Watch movement according to Claim 3 or 4, characterized in that it comprises a stop device (24, 26, 31) arranged for locking said stop wheel (22) in a predefined angular position and for periodically releasing it in order to allowing said coil spring (18) to be recharged from said main power source (1), according to a predefined amplitude, through said main shaft (8) and said stop wheel. Clock movement according to claim 5, characterized in that said stop device (24, 26, 31) is arranged to release said stop wheel (22) every six seconds. Clock movement according to claim 5 or 6, characterized in that said stop wheel (22) has a peripheral toothing arranged to cooperate with a control anchor (31) can be moved between first and second extreme positions, following the relative angular position of a cam (26) whose rotational movements are controlled from a mobile (13, 24) of said train, said stop wheel being arranged to be free to turn from an angle predefined when passing the control anchor from one to the other of its two extreme positions. Clock movement according to any one of the preceding claims, characterized in that said adjustment member (20) has a circular periphery provided with a knurling or toothing (41) forming said bearing surface. Clock movement according to claim 8, characterized in that it further comprises a control wheel (42) adjacent said adjustment wheel (9) and comprising a toothed pinion (44) capable of cooperating with said bearing surface ( 41) of said adjustment member (20). Clock movement according to claim 9, characterized in that said pinion gear (44) is movable in translation between a first position of rest, wherein it is relieved of said bearing surface (41), and a second adjustment position in which it meshes with said bearing surface. Clock movement according to claim 10, characterized in that said first position is a high position while said second position is a depressed position, said control mobile (42) further comprising an elastic member (48) arranged to hold said pinion gear (44) in its high position in the absence of any external action. Clock movement according to any one of claims 9 to 11, characterized in that said control wheel (42) is provided with at least one slot (50) adapted to cooperate with a tool in order to drive said toothed pinion (44). ) in rotation. Clock movement according to any one of claims 3 to 12, characterized in that said stop wheel (22) and said second member (10) are arranged relative to each other in such a way that said fixing element (23) defines an abutment limiting their relative rotational movements. Timepiece with a watch movement according to any one of claims 1 to 13.

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