EP1139182A1 - Reserve power indicating mechanism and timepiece provided with such a mechanism - Google Patents

Abstract

Power reserve indicator mechanism for a timepiece movement of the type provided with an energy source formed by a mainspring (26), comprising a frame (10, 12, 14, 16), an indicator for power reserve and a differential gear (30) with a first input (44) connected to a mobile (29) driven in rotation during the winding of the mainspring, a second input (42) connected to a mobile (20) driven in rotation during the disarming of the mainspring, and an output (36a) connected to said indicator, in which the indicator is capable of traversing a given angle comprised between two extreme positions, defined by a stop (78). According to the invention, an intermediate mobile (32) is interposed between the output of the differential gear and said indicator and comprises an elastic member (64) arranged so that the differential gear continues to rotate freely while the indicator remains in abutment. <IMAGE>

Description

The present invention relates to reserve indicator mechanisms step for movement of a timepiece of the type provided with a source of energy formed by a mainspring. 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 driven mobile in rotation during winding of the mainspring, a second input connected to a mobile driven in rotation during the disarming of the mainspring, and a output connected to the power reserve indicator. In this mechanism, the indicator is likely to travel a given angle between two extreme positions, the first of which 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 winding watch automatic "by B. Humbert, Scriptar edition, Lausanne 1955, on page 85. It is fitted with an indicator mounted frictionally on a mobile connected to the outlet of the differential. The indicator moves between two defined extreme positions by stops. When the indicator arrives at one of the stops, from the limit upper arm or disarm of the mainspring, it remains stationary while the mainspring continues to be armed or disarmed, the friction allowing movement of the gear train while the indicator is fixed.

Such a solution therefore gives an idea of the actual armament of the mainspring but there may be significant differences from cycle to cycle the other, due to the relative displacement of the indicator relative to the train. The object of the present invention is to overcome this drawback.

To this end, the mechanism according to the invention is characterized in that a mobile intermediate is interposed between the output of the differential gear and the indicator and has an elastic member and two coaxial parts one formed by a wheel, the other by a shaft, one connected to the gear differential, the other to the indicator and to each other by the elastic member, the mobile being arranged so that the two parts rotate jointly as long as the indicator occupies a position between the two extreme positions and in that, at least when the indicator occupies in its second extreme position, the differential gear continues to rotate freely while the indicator remains in abutment and the elastic member arms as long as the mainspring drives the movement.

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

In a particularly interesting embodiment, the first organ elastic comprises a cam, integral in rotation with the shaft of the mobile intermediate, 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 as to that the free end of the spring slides on the cam when the indicator is in stop and the mainspring continues to disarm and generates a torque opposite to that exerted by the mainspring.

In this way, each position of the indicator corresponds to a level of arming of the mainspring. In addition, the part can 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 engine torque, leading to a loss of amplitude of the pendulum.

It is obvious that such a mechanism must include a set of gears to be able to operate normally. Now this set of gears affects the accuracy of the information indicated. Also, to further improve the agreement between the position of the indicator and the winding of the mainspring, the mechanism according to the invention advantageously comprises a second elastic member arranged to exert a permanent torque on the train of gears comprised between the two inputs of the differential gear and the mobile intermediate

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

Depending on how the second elastic organ works, it can result more or less significant fluctuations in the amplitude of the pendulum. In indeed, if the mainspring must arm the second elastic member as and as it disarms itself, the useful torque decreases accordingly. However, the winding torque increases as the mainspring disarms. This is why, in order to ensure an optimal 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 ensuring an 8-day power reserve.

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 characteristics 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 lines II-II, III-III and IV-IV of Figure 1.

The mechanism according to the invention is associated with a watch movement such only partially shown in the drawing. This movement includes, conventionally, a chassis formed by a plate 10 and several bridges fixed on this plate 10, three of which are visible in the drawing, i.e. a bridge of barrel 12 (Figure 2), a differential bridge 14 (Figures 2 and 3) and a bridge power reserve indicator 16 (Figures 3 and 4). The plate and the bridges are intended to support and position the various mobile components of the movement.

As can be seen in Figure 2, this movement has a source of energy formed by a barrel 18, which comprises a drum 20, a cover 22, a shaft 24 and a motor spring schematically shown at 26. The mainspring 26 is arranged inside the drum and fixed, in a conventional manner, to the wall of the drum by one of its ends and to the tree by the other. The drum 20 is closed by the cover 22 which is fixed to notch in a drum groove, not referenced to avoid overloading the drawing.

The drum 20 and the cover 22 together form a movable assembly rotating on the shaft 24.

The shaft 24 pivots, on the one hand, in the plate 10, on the other hand in the bridge of barrel 12. It carries, on a square 24a and beyond the bridge 12, a wheel with ratchet 28 provided, at its periphery, with teeth 28a. His training in rotation, by means of a winding crown, which has not been shown, ensures the winding of the mainspring 26.

The drum 20 is provided, at its periphery, with a toothing 20a intended to drive the gear train 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, a mobile intermediate 32 and an indicator mobile 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, one end of which has a toothing forming a pinion 36a. It has two intermediate portions 36b and 36c, and a pivot 36d occupying the other end and engaged mobile in rotation in a stone 52 driven into bridge 14. It can rotate around an axis perpendicular to the plane of the plate 10.

The satellite carrier 38 is formed of a metal part provided with a hole central 38a cylindrical. He is chased on the tree 36, which is engaged by his portion 36c in hole 38a. It has, in its middle part, a cylindrical protrusion 38b extending radially and provided with a hole tapped 38c intended to receive the screw 50. It further comprises two portions cylindrical 38d and 38e, coaxial with hole 38a.

The protuberance 38b carries the satellite 40 which can rotate freely around 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 below.

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

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

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

The ring 46 is formed of a plate 46a and a sleeve 46b. She is engaged on the portion 36b of the shaft 36 and bearing against the pinion 36a by the end of the sleeve 46b. The latter is engaged, by its surface outside, in a stone 54 driven into plate 10. Plate 46a stop form for the satellite carrier 38.

The ring 48, formed of a round plate pierced in its center, is driven out by force 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 tigeron 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 tigeron 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 FIG. 1, the wheel 60 is formed of a board whose periphery is provided with a toothing 60a, which meshes with the teeth 36a of the pinion 36. It is mounted to rotate freely on portion 58c. The board has an oblong orientation hole radial 60c whose function will be specified later.

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

The spring 64 is formed by an elastic blade in an arc of a circle embracing a angle of about 270 °. It is fixed, by one of its ends and so known to the plate of the wheel 60. The other end forms a protuberance 64a arranged so that it is in abutment against the cam 62, in its concave portion 62a. A finger 64b, arranged in the middle part of the protuberance 64a, is engaged in hole 60c.

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

Plate 34a has a cutout 34d in the form of an 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 fitted with a mechanism as described above, the motor spring 26, disarming, rotates and in a conventional manner the barrel drum 20, the toothing 20a of which meshes with the first mobile in the gear train. The latter is connected to a escapement, which maintains the movement of a balance-spring.

If the drum 20 rotates during the disarming of the mainspring 26, the shaft 24 is, however, immobile. The wheel 42 of the differential 30 is therefore driven in rotation, while the wheel 44 remains fixed. The pinion 42c, which rotates with the wheel 42, meshes with satellite 40.

As the wheel 44 is stationary and with it the pinion 44c, the satellite 40 does not can rotate only by driving the satellite carrier 38. The latter, which carries the pinion 36a, rotates the intermediate mobile 32, itself driving the mobile indicator 34.

Thus, as the mainspring 26 disarms, the mobile indicator 34 moves opposite a scale arranged on the dial of the shows, until reaching the lower limit of normal operation. In below this limit, the movement can still function during a time. However, its accuracy is likely to decrease, due to loss of amplitude of the pendulum. The power reserve indicator indicates so that it is exhausted and the indicator mobile 34 is immobilized, the end of the cut 34d being in abutment against the pin 78.

If the watch user still does not wind the mainspring 26, this one continues its disarming by making function 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 therefore has a relative movement with respect to 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 cam 62 from concave portion 62a towards one bosses. The deformation of the spring 64 is done only radially, because of the finger 64b engaged in the hole 60c. Disarming the mainspring 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 winds up the mainspring 26 by turning the winding crown, it drives the ratchet wheel 28 and, by via the reference 29, the input wheel 44. The latter rotates the planet carrier 38 in the opposite direction to that 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 it finds the concave portion 62a. That's when the pinion 58 is again driven and, with it, the indicator wheel 34, so as the indicator moves opposite 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 perfectly match the position maximum spring winding with the extreme position of the indicator corresponding to the largest power reserve. It is why, in this position also, the indicator mobile can be stopped by the pin 78. Here too, the spring 64 is used, the protuberance 64a sliding on the other blank of the cam 62.

The mechanism as described involves a gear train whose mobile phones must have a sufficient play between them to avoid any jamming during operation. Because of this frolic, the position of the indicator does not correspond to the same degree of winding of the mainspring, depending on whether it is being armed or disarmed. It also results that at the start of the arming operation by the user, the latter does not see the indicator to move only after the set of gears has been taken, which gives the impression that the mechanism is not working as it should. The device shown in Figure 4 eliminates this defect

More specifically, the mechanism according to the invention comprises, advantageously, a complementary elastic member 66 intended to generate torque on the gear train leading to the needle of power reserve indicator, in order to eliminate this jagged 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 to a tigeron 76 secured to the platinum 10.

The drum 68 and the cover 70 together form a housing in which is the spring 74. The latter is connected, in a conventional manner, by one of its ends to the shaft 72 and 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 teeth 60a of the wheel 60. The shaft 72 is rigidly mounted on the tigeron 76, so that it cannot rotate.

In a variant which has not been shown, it would also be possible that the toothing 68a is engaged with the indicator mobile 34 rather than with that of the mobile 32. However, this is not essential, because the debate between the pinion 58 of the intermediate mobile 32 and the wheel of the mobile 34 is extremely low compared to the amount of discrepancy noted at the differential 30.

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

The member 66, thus described, exerts a permanent torque on the train gears comprised between the two input wheels 42 and 44 of the differential 30 and the intermediate mobile 32.

The mechanism according to the invention is particularly well suited to watches with manual winding, in particular with so-called 8-day watches, that is to say those whose mainspring allows a running autonomy of more than one week. It is also applicable in automatic watches fitted a stop system blocking the winding of the mainspring when it is fully armed.

This mechanism can be the subject of many variants without however depart from the scope of the invention. So the differential could be flat rather that spherical. It is also possible to apply the mechanism to a watch movement comprising two barrels. In this case, the wheels differential input can be kinematically connected to the wheel at ratchet of one of the barrels and to the drum of the other or of the same barrel.

Claims (7)

Power reserve indicator mechanism for a timepiece movement of the type provided with an energy source formed by a mainspring (26), comprising a frame (10, 12, 14, 16), an indicator for power reserve and a differential gear (30) with a first input (44) connected to a mobile (29) driven in rotation during the winding of the mainspring, a second input (42) connected to a mobile (20) rotated when disarming the mainspring, and an output (36a) connected to said indicator, in which the indicator is capable of traversing a given angle comprised between two extreme positions, the first of which is occupied when the mainspring is armed and the second, defined by a stop (78), when the mainspring is disarmed, characterized in that an intermediate mobile (32) is interposed between the output of the differential gear and said indicator and comprises an elastic member (64) and two coaxial parts formed one of a wheel (60), the other of a shaft (58), connected one to said outlet (36a), the other to said indicator and to each other by said member elastic, said mobile being arranged so that the two parts rotate together as long as the indicator occupies a position between said extreme positions and in that , at least when said indicator occupies its second extreme position, said gear continues to rotate freely while the indicator remains in abutment and the elastic member is armed, as the motor spring drives said movement. Mechanism according to claim 1, characterized in that the part connected to said gear is the wheel (60). Mechanism according to claim 2, characterized in that the first elastic member comprises a cam (62), integral in rotation with said shaft, and a spring (64), deformable radially and rigidly fixed by one of its ends to said wheel ( 60), in which the cam cooperates with the free end (64a) of said spring, the whole 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 disarm and generate a torque opposite to that exerted by the mainspring. Mechanism according to one of claims 1 to 3, characterized in that it further comprises a second elastic member (66) arranged to exert a permanent torque on the gear train comprised between the two input wheels ( 42, 44) of the differential gear and the intermediate mobile (32). Mechanism according to claim 4, characterized in that the second elastic member (66) comprises a shaft (72) rigidly fixed to said frame (10), a drum (68) provided, at its periphery, with teeth (68a) which meshes with the part (60) of the mobile connected to said indicator, and a leaf spring (74) disposed in said drum and fixed, by one of its ends, to the shaft of the second elastic member and, by the other to said drum . Mechanism according to claim 4 or 5, characterized in that the second elastic member (66) is arranged so that it arms and disarms simultaneously with the mainspring (26). Watch provided with a mechanism according to one of claims 1 to 6, characterized in that its motor spring (26) provides a power reserve equal to at least 8 days.

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