EP1139182B1 - Reserve power indicating mechanism and timepiece provided with such a mechanism - Google Patents

Description

The present invention relates to power reserve indicator mechanisms for a timepiece movement of the type provided with an energy source formed by a motor spring. Conventionally, the mechanism according to the invention comprises a frame, a power reserve indicator and a differential gear with a first input connected to a mobile driven in rotation during the winding of the mainspring, a second input connected to a mobile rotated during disarming of the mainspring, and an output connected to the power reserve indicator. In this mechanism, the indicator is likely to traverse a given angle between two extreme positions, the first is occupied when the mainspring is armed and the second, defined by a stop, when the mainspring is disarmed.

A mechanism of this type is described in "The Swiss automatic winding watch" by B. Humbert, Scriptar edition, Lausanne, 1955, on page 85. It is provided with a friction mounted indicator on a mobile connected to the output of the differential . The indicator moves between two extreme positions defined by stops. When the indicator arrives at one of the stops, the upper limit of winding or disarming of the mainspring, it remains stationary while the mainspring continues to be armed or disarmed, the friction allowing the displacement of the gear while the indicator is fixed.

The document CH 89272 discloses a gait indicator mechanism having a differential gear and an indicator capable of traversing a given angle.

Such a solution therefore makes it possible to get an idea of the actual winding of the mainspring, but there may be significant differences from one cycle to another, due to the relative displacement of the indicator relative to the gear train. The object of the present invention is to overcome this drawback.

For this purpose, the mechanism according to the invention is characterized in that an intermediate mobile is interposed between the output of the differential gear and the indicator and comprises an elastic member and two coaxial parts formed one of a wheel , the other of a shaft, connected one to the differential gear, the other to the indicator and one to the other by the elastic member, the mobile being arranged so that the two parts rotate together as long as the indicator occupies a position between the two extreme positions and in that, at least when the indicator occupies its second extreme position, the differential gear continues to rotate freely while the indicator remains in position. stop and that the elastic member is armed, as long as the mainspring causes the movement.

Advantageously, it is the wheel of the mobile interposed between the differential gear and the indicator which meshes with the output of the differential gear.

In a particularly advantageous embodiment, the first resilient member comprises a cam, integral in rotation with the shaft of the intermediate mobile, and a radially deformable spring rigidly fixed by one of its ends to the wheel of the intermediate mobile. This cam cooperates with the free end of this spring. The whole is arranged so that the free end of the spring slides on the cam when the indicator is in abutment and that the mainspring continues to disarm and generates a reverse torque to that exerted by the mainspring.

In this way, at each position of the indicator corresponds a winding level of the mainspring. In addition, the part may continue to operate when the indicator has reached the lower limit. The user is, however, informed that the accuracy of his watch is likely to have been affected by insufficient motor torque, leading to a loss of amplitude of the balance.

It is obvious that such a mechanism must include a set of gears to be able to function normally. But this set of gears affects the accuracy of the indicated information. Also, to further improve the match between the position of the indicator and the armature of the motor-spring, the mechanism according to the invention advantageously comprises a second elastic member arranged to exert a permanent torque on the gear train included between the two inputs of the differential gear and the intermediate mobile

In a particularly safe embodiment, the second elastic member comprises a shaft rigidly fixed to the frame, a drum provided at its periphery with a toothing which meshes with the portion of the mobile connected to the indicator, and a leaf spring disposed in the drum and fixed at one end to the shaft of the second elastic member and the other to the drum.

Depending on the way in which the second elastic member works, it may result in more or less significant fluctuations in the amplitude of the balance. Indeed, if the motor spring must arm the second elastic member as it disarms itself, the useful torque decreases accordingly. However, the armature torque increases as the mainspring disarms. This is why, in order to ensure an optimum amplitude of the balance, the second elastic member is arranged so that it arms and disarms simultaneously with the mainspring.

Such a mechanism is particularly well suited to equip a watch comprising a motor spring providing a power reserve of 8 days.

• La figure 1 montre, en plan, un mécanisme selon l'invention, et
• les figures 2, 3 et 4 sont des coupes respectivement selon les lignes II-II, III-III et IV-IV de la figure 1.

Other advantages and features of the invention will emerge from the description which follows, given with reference to the appended drawing, in which:

• FIG. 1 shows, in plan, a mechanism according to the invention, and
• Figures 2, 3 and 4 are sections respectively along the lines II-II, III-III and IV-IV of Figure 1.

The mechanism according to the invention is associated with a watch movement as partially shown in the drawing. This movement comprises, in a conventional manner, a frame formed of a plate 10 and several bridges fixed on this plate 10, three of which are visible in the drawing, namely a barrel bridge 12 (FIG. 2), a differential bridge 14 (FIG. Figures 2 and 3) and a power reserve indicator bridge 16 (Figures 3 and 4). The plate and the bridges are intended to support and position the various moving components of the movement.

As can be seen in Figure 2, this movement comprises a power source formed of a barrel 18, which comprises a drum 20, a cover 22, a shaft 24 and a motor spring schematically shown in 26. The spring Motor 26 is disposed within the drum and is conventionally attached to the drum wall at one end and to the shaft at the other end. The drum 20 is closed by the cover 22 which is fixed notch in a groove of the drum, not referenced to avoid overloading the drawing.

The drum 20 and the lid 22 form, together, an assembly rotatably mounted on the shaft 24.

The shaft 24 pivots, on the one hand, in the plate 10, on the other hand in the barrel bridge 12. It carries, on a square 24a and beyond the bridge 12, a wheel to ratchet 28 provided, at its periphery, a toothing 28a. Its rotation drive, by means of a winding crown, which has not been shown, makes it possible to wind the mainspring 26.

The drum 20 is provided at its periphery with a toothing 20a for driving the finishing gear which is not shown in the drawing either.

The mechanism according to the invention comprises a reference 29, a differential 30 pivotally mounted between the plate 10 and the differential bridge 14, an intermediate mobile 32 and a mobile indicator 34 (Figure 3).

More specifically, the differential 30 comprises a shaft 36, a planet carrier 38 on which are mounted a satellite 40, a first input wheel 42 and a second input wheel 44, two assembly rings 46 and 48 and a screw 50.

The shaft 36 is formed of a steel rod whose one end has a toothing forming a pinion 36a. It comprises two intermediate portions 36b and 36c, and a pivot 36d occupying the other end and engaged in rotation in a stone 52 driven into the bridge 14. It can rotate about an axis perpendicular to the plane of the plate 10.

The planet carrier 38 is formed of a metal part provided with a cylindrical central hole 38a. It is driven on the shaft 36, which is engaged by its portion 36c in the hole 38a. It comprises, in its middle part, a cylindrical protuberance 38b extending radially and provided with a threaded hole 38c for receiving the screw 50. It further comprises two cylindrical portions 38d and 38e, coaxial with the hole 38a.

The protrusion 38b carries the satellite 40 which can rotate freely about an axis perpendicular to the axis of rotation of the shaft 36. This satellite 40 is provided with a conical toothing 40a whose function will be specified later.

The two cylindrical portions 38d and 38e carry, respectively, the wheels 42 and 44, adjusted so as to freely rotate therein. These wheels are disposed between the protuberance 38b and respectively the rings 46 and 48.

The wheels 42 and 44 are each formed by a board, identified by the letter a and whose periphery bears a toothing b , and a pinion c provided with a conical toothing d . The wheel 42 meshes, by its toothing 42b, with the toothing of the barrel 20a. The wheel 44 meshes, by its teeth 44b, with the reference 29, which meshes with the toothing 28a of the ratchet wheel 28 (Figure 2). Finally, the teeth 42d of the pinion 42c and 44d of the pinion 44c are engaged with the toothing 40a of the satellite 40 (Figure 3).

It will be noted that the gear ratios between the toothing 20a of the drum drum and the first input wheel 42, on the one hand, and that of the ratchet wheel 28 and the second input wheel 44, d on the other hand, must be equal, so that for the same angle traveled by the barrel and the ratchet wheels 42 and 44 travel at equal angles.

The ring 46 is formed of a plate 46a and a sleeve 46b. It is engaged on the portion 36b of the shaft 36 and bears against the pinion 36a by the end of the sleeve 46b. The latter is engaged, by its outer surface, in a stone 54 driven into the plate 10. The plate 46a forms a stop for the planet carrier 38.

The ring 48, formed of a round plate pierced at its center, is forced out on the end of the portion 36c of the shaft 36. With the ring 46, it ensures the assembly of all the parts forming the differential 30.

The intermediate mobile 32 is pivotally mounted on the plate 10 by means of a rod 56. It essentially comprises a pinion 58, a wheel 60, a cam 62 and a connecting spring 64.

More specifically, the pinion 58 comprises a sleeve 58a pivotally mounted on the rod 56. It is provided at one of its ends with a toothing 58b. The sleeve 58a is formed of two cylindrical portions 58c and 58d, of different outside diameters.

As can be seen more particularly in Figure 1, the wheel 60 is formed of a board whose periphery is provided with a toothing 60a, which meshes with the toothing 36a of the pinion 36. It is mounted free to rotate on portion 58c. The board is provided with an oblong hole with radial orientation 60c whose function will be specified later.

The cam 62 has a shape similar to that of a chronograph core, with a concave portion 62a and two adjoining bosses that have not been referenced. It is driven on the cylindrical portion 58d and axially maintains the wheel 60.

The spring 64 is formed of an elastic arcuate blade blazing an angle of about 270 °. It is fixed, by one of its ends and in known manner to the board of the wheel 60. The other end forms a protuberance 64a arranged so that it bears against the cam 62, in its portion concave 62a. A finger 64b, disposed in the median portion of the protuberance 64a, is engaged in the hole 60c.

The mobile indicator 34 is pivotally mounted on a pin 66 driven into the plate 10. It comprises a board 34a provided at its periphery with a toothing 34b meshing with the toothing 58b of the pinion 58, and a barrel 34c extending beyond the plate and intended to carry a power reserve indicator needle, not shown in the drawing.

The board 34a has a cutout 34d shaped annular sector embracing an angle of about 150 °. A pin 78, driven into the plate 10, is engaged in the cutout 34d and serves as a stop for the mobile 34.

In a watch movement provided with a mechanism as described above, the motor spring 26, disarming, drives in rotation and in conventional manner the barrel drum 20 whose toothing 20a meshes with the first mobile of the gear train finishing. The latter is connected to an escapement, which maintains the movement of a sprung balance.

If the drum 20 rotates during the disarming of the motor spring 26, the shaft 24 is, for against, immobile. The wheel 42 of the differential 30 is therefore rotated, while the wheel 44 remains fixed. Pinion 42c, which rotates with wheel 42, meshes with satellite 40.

As the wheel 44 is stationary and with it the pinion 44c, the satellite 40 can rotate only by driving the planet carrier 38. The latter, which carries the pinion 36a, rotates the intermediate wheel 32, itself driving the mobile indicator 34.

Thus, as the mainspring 26 disarms, the mobile indicator 34 moves next to a scale disposed on the dial of the watch, until reaching the lower limit of normal operation. Below this limit, the movement may still work for a period of time. However, its accuracy is likely to decrease, because of the amplitude loss of the pendulum. The power reserve indicator therefore indicates that it is exhausted and the mobile indicator 34 is immobilized, the end of the cutout 34d being in abutment against the pin 78.

If the user of the watch still does not raise the mainspring 26, it continues to disarm by operating the movement of the watch. The differential 30 therefore continues to rotate and, with it, the wheel 60.

As the pinion 58 meshes with the indicator mobile 34, it is blocked. The wheel 60 thus has a relative movement with respect to the pinion 58. This movement is made possible because the wheel 60 is connected to the pinion 58 by the connecting spring 64, which is driven by the wheel 60. The protuberance 64a slides on the cam 62 of the concave portion 62a towards one of the bosses. The deformation of the spring 64 is radial only, because of the finger 64b engaged in the hole 60c. Disengagement of the motor spring 26 can be done until the torque applied to the balance is insufficient to maintain its movement, so that the watch stops.

When the user of the watch raises the mainspring 26 by turning the winding crown, it drives the ratchet wheel 28 and, through the return 29, the input wheel 44. The latter rotates the door -satellite 38 in the opposite direction to that which is generated by the movement of the drum 20. As a result, the pinion 36a rotates the wheel 60 so that the protrusion 64a slides, in the opposite direction, on the cam 62 until 'to find the concave portion 62a. It is then that the pinion 58 is again driven and, with it, the indicator wheel 34, so that the indicator moves next to the scale of the dial. This indicator reaches the upper end of this scale when the mainspring 26 is fully armed.

In practice, it is difficult to make perfectly coincide the maximum winding position of the mainspring with the extreme position of the indicator corresponding to the largest power reserve. Therefore, in this position also, the mobile indicator can be stopped by the pin 78. Here again, the spring 64 is put to contribution, the protuberance 64a sliding on the other side of the cam 62.

The mechanism as described involves a gear train whose mobiles must have between them, sufficient frost to avoid jamming during operation. Because of this fretting, the position of the indicator does not correspond to the same degree of winding of the mainspring, depending on whether it is being wound up or disarmed. It also results that at the beginning of the operation of arming by the user, the latter does not see the indicator move until after the gear set has been taken, which gives him the impression that the mechanism does not work as it should. The device represented in FIG. 4 makes it possible to eliminate this defect

More specifically, the mechanism according to the invention advantageously comprises a complementary elastic member 66 intended to generate a torque on the gear train leading to the power reserve indicator needle, in order to eliminate this frustum. gears.

The member 66 is formed of a barrel comprising a drum 68, a cover 70, a shaft 72 and a spring 74. It is fixed on a rod 76 integral with the plate 10.

The drum 68 and the cover 70 form, together, a housing in which the spring 74 is located. The latter is connected, in a conventional manner, by one of its ends to the shaft 72 and by the other to the drum 68 . It is arranged so that it arms and disarms at the same time as the mainspring 26.

The drum 68 is provided with a toothing 68a at its periphery, in engagement with the toothing 60a of the wheel 60. The shaft 72 is rigidly mounted on the rod 76, so that it can not rotate.

In a variant that has not been shown, it would also be possible for the toothing 68a to be engaged with the indicator wheel 34 rather than with that of the wheelchair 32. This is however not essential, since the frolicking between pinion 58 of the intermediate mobile 32 and the wheel of the mobile 34 is extremely low compared to the frog found at the differential 30.

With such a configuration, it is necessary to be attentive to the fact that the torque generated by the spring 74 must be less than the torque necessary for the protuberance 64a to leave the concave portion 62a. If this were not the case, it would result in a shift of the indicator corresponding to the relative movement of the pinion 58 and the wheel 60 under the effect of the spring pair 74, which would be counterproductive .

The member 66, as described, exerts a permanent torque on the gear train between the two input wheels 42 and 44 of the differential 30 and the intermediate wheel 32.

The mechanism according to the invention is particularly well suited to watches with manual winding, especially the so-called 8 days watches, that is to say those whose motor spring allows a range of more than a week. It is also applicable in automatic watches equipped with a stop system blocking the winding of the mainspring when fully armed.

This mechanism can be subject to many variations without departing from the scope of the invention. Thus, the differential could be flat rather than spherical. It is also conceivable to apply the mechanism to a watch movement comprising two barrels. In this case, the differential input wheels can be kinematically connected to the ratchet wheel of one of the barrel and the drum of the other or the same barrel.

Claims (7)

1. Power reserve indicator mechanism for a timepiece movement of the type fitted with a power source formed of a motor spring (26), including a frame (10, 12, 14, 16), a power reserve indicator and a differential gear (30) with a first input (44) connected to a wheel (29) driven in rotation when the motor spring is wound, a second input (42) connected to a wheel (20) driven in rotation when the motor spring is let down, and an output (36a) connected to said indicator, wherein the indicator is capable of covering a given angle comprised between two end positions, the first of which is occupied when the motor spring is wound and the second, defined by a stop (78), when the motor spring is let down,
   characterized in that an intermediate wheel (32) is inserted between the output of the differential gear and said indicator and includes a resilient member (64) and two coaxial parts, one formed of a wheel (60), and the other of an arbor (58), one connected to said output (36a), the other to said indicator and connected to each other by said resilient member, said wheel being arranged so that the two parts rotate together while the indicator occupies a position comprised between said two end positions and in that, at least when said indicator occupies its second end position, said gear continues to rotate freely while the indicator remains in abutment (against stopping means), and the resilient member is wound, while the motor spring drives the movement.
2. Mechanism according to claim 1, characterized in that the part connected to said gear is the wheel (60).
3. Mechanism according to claim 2, characterized in that the first resilient member includes a cam (62), secured in rotation to said arbor, and a spring (64) able to deform radially and rigidly fixed via one of its ends to said wheel (60), wherein the cam cooperates with the free end (64a) of said spring, the assembly arranged so that the free end of the spring slides on the cam when the indicator is in abutment and the motor spring continues to be let down and generate an opposite torque to that exerted by the motor spring.
4. Mechanism according to any of claims 1 to 3, characterized in that it further includes, a second resilient member (66) arranged to exert a permanent torque on the gear train comprised between the two input wheels (42, 44) and the differential gear and the intermediate wheel (32).
5. Mechanism according to claim 4, characterized in that the second resilient member (66) includes an arbor (72) rigidly fixed to said frame (10), a drum (68) provided, at its periphery, with a toothing (68a) which meshes with the part (60) of the wheel connected to said indicator, and a strip spring (74) arranged in said drum and fixed, via one of its ends, to the arbor of the second resilient member and, via the other, to said drum.
6. Mechanism according to claims 4 or 5, characterized in that the second resilient member (66) is arranged so that it is wound and let down simultaneously with the motor spring (26).
7. Watch fitted with a mechanism according to any of claims 1 to 6, characterized in that its motor spring (26) assures a power reserve equal to at least 8 days.

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