EP1978424B1 - Chronograph - Google Patents

Description

The present invention relates to a chronograph comprising a first kinematic chain between a motor spring and an escapement associated with the regulating system, and a second kinematic chain of which a mobile of a first end is in selective desmodromic connection with the first kinematic chain by intermediate of a clutch device.

The chronograph mechanisms, such as those described in The Chronograph, its operation, its repair by B. Humbert Edition of the Swiss Journal of Watchmaking and Jewelry Scriptar SA Lausanne (1952), are selectively connected to the finishing gear of a workpiece. watchmaking, usually at the seconds wheel, so that the chronograph hand does one lap per minute and at each turn, drives a mobile one minute counter.

Given this way of training the chronograph train, this cog is not powered. To avoid gearing which would result in a flutter of the seconds hand of the chronograph, the number of teeth of the chronograph wheel has been multiplied, these teeth being triangular and a slight braking spring has also been added.

According to GB 1,412,340 , the chronograph mechanism is mounted as a bypass on the finishing train and comprises, at its pto end connected to the finishing train, a clutch device and a locking device, working in synchronization and, in the vicinity of its terminal end, at least one braking device, all so that, during the disengagement which isolates from the gear train the entire chronograph mechanism, the chronograph wheel is retained at both ends by the locking and braking devices, preventing any gear flutter.

It follows from these different measures that the energy provided by the finishing gear is not negligible and that this energy is subtracted from that which is supplied to the exhaust and therefore the drive of the balance. However, the regularity of the energy transmitted to the pendulum depends on the accuracy of its oscillation frequency and therefore that of the timepiece.

In the case of a wristwatch, given firstly, the relatively small diameter of the dial which is between 25 and 40mm and secondly, the frequency of the pendulum which is generally 21,600 vibrations / hour or of 18,000 vibrations / hour, the smallest division of time that can be measured with such a mechanism and such a dial diameter is limited in practice to 0.16s or 0.2s, corresponding to an angle of 1 ° or 1 ° 12 ', which corresponds to the movement of the second chronograph hand, by successive jumps in the value of one of these angles. The measurement of the smallest interval is therefore dependent on the frequency with which the balance oscillates and actuates the escape at each alternation (half-oscillation). So even a reduction in the rotation of the second chronograph wheel would depend on the frequency of the oscillator which allows the rotation of the gear train only by successive jumps. In addition, a smaller time interval would not be readable on a scale of this diameter.

The present invention aims to remedy at least in part the aforementioned drawbacks, so as to remove the energy withdrawal of the chronograph train on the gear train. The object of the invention is also to very significantly reduce the smallest measurable time interval, even in the case of a wristwatch chronograph.

For this purpose, the subject of the present invention is a chronograph as defined by claim 1.

The essential difference between the chronograph object of the invention and those of the state of the art, comes from the fact that the energy required to drive the chronograph train is no longer taken from the gear train, but directly on a spring, advantageously on the mainspring of the watch chronograph movement. The chronograph wheel is then regulated by an escape wheel which controls the speed of rotation of the chronograph train driven directly by a mainspring as the finishing gear.

Advantageously, this drive mode offers the possibility of being able to very substantially increase the measurement range, thanks to a mobile which performs a rotation per second, which allows without difficulty to measure the hundredth of a second.

• La figure 1 est une vue en plan côté cadran du mécanisme de chronographe en position de marche;
• la figure 1.1 est une vue de détail en coupe selon la ligne I-I de la figure 1;
• la figure 2 est une vue semblable à la figure 1 du mécanisme de chronographe en position d'arrêt;
• la figure 2.2 est une vue en coupe semblable à la figure 1.1 dans la position du mécanisme illustré par la figure 2;
• la figure 3 est une vue semblable aux figures 1 et 2 dans la position de remise à zéro;
• la figure 3.1 est une vue de détail en coupe selon la ligne III-III de la figure 3;
• la figure 4 est une vue de détail en plan du barillet-moteur du mécanisme de chronographe dont seule l'emplacement est indiqué sur les figures 1 à 3;
• la figure 5 est une vue en élévation du barillet de la figure 4;
• la figure 6 est une vue en élévation partielle du rouage de chronographe.

Other features and advantages of the present invention will become apparent from the description which follows, and with the aid of the accompanying drawings which illustrate, schematically and by way of example, an embodiment of the chronograph object of the invention. 'invention.

• The figure 1 is a dial plan view of the chronograph mechanism in the on position;
• the figure 1.1 is a detail view in section along line II of the figure 1 ;
• the figure 2 is a view similar to the figure 1 the chronograph mechanism in the off position;
• the figure 2.2 is a sectional view similar to the figure 1.1 in the position of the mechanism shown by the figure 2 ;
• the figure 3 is a view similar to figures 1 and 2 in the reset position;
• the figure 3.1 is a detail view in section along line III-III of the figure 3 ;
• the figure 4 is a detailed plan view of the engine cylinder of the chronograph mechanism whose only location is indicated on the Figures 1 to 3 ;
• the figure 5 is an elevation view of the barrel of the figure 4 ;
• the figure 6 is a partial elevation view of the chronograph wheel.

The figures in the drawing essentially illustrate the chronograph mechanism. The finishing gear and the clockwork control system are not illustrated, as they are not necessary for the understanding of the invention.

Only two elements common to the chronograph mechanism and to the watch movement are represented, the barrel 1 and an escapement wheel 2 of the chronograph mechanism, integral with the axis of the escapement wheel of the clockwork movement which it is not represented. This escapement mobile 2 of the chronograph mechanism rotates in this example, in the direction of arrow F at the rate of one turn in 5 seconds and has a sawtooth gear of 75 teeth selectively engaged with the last mobile 4f of the kinematic chain of the chronograph train 4, the first mobile 4a meshes with a toothing 1b of the barrel 1 which has two independent teeth 1a, 1b, the toothing 1a meshing with the work train. This last mobile 4f of the chronograph train has 15 teeth, so that it makes one revolution per second when it is engaged with the escapement mobile 2 of the chronograph.

Advantageously, the cylinder 1 is at the center of the movement of the timepiece. The outer end of the spring 6 of the barrel 1 is integral with the barrel drum provided with teeth 1a which leads, as usual, the first mobile (not shown) of the work train, while the inner end of the spring 6 is integral with the shaft 1d of the barrel 1 as usual. On the other hand, the shaft of the barrel 1 is integral with a winding wheel 8 which, unlike the traditional ratchet, is not associated with a ratchet and can therefore rotate in both directions.

The toothed lid 1b of the barrel 1 is pivotally mounted on a cylindrical portion 1c of the shaft 1d of this barrel 1 ( figure 5 ) and meshes with the first mobile 4a of the kinematic chain of the chronograph train 4. This toothed lid 1b is connected to a portion of square section 1e of the barrel shaft 1d by a ratchet drive wheel 15 secured to the barrel shaft with the square section portion 1c and the ratchet gear is engaged with two pawls 16 ( figure 4 ), pressed into this toothing ratchet by two leaf springs 17a integral with a ring 17. The latter is connected to the toothed lid 1b by four lugs 9 integral with the toothed lid 1b engaged in four respective openings 10 in arcs of circles, allowing relative rotation between the ring 17 and the toothed lid 1b of an angle corresponding to that of the openings 10 in arcs of circles. The outer edge of the ring 17 has a ratchet toothing 17b engaged with a retaining pawl 18.

An auxiliary drive member 19 is further disposed on the cylindrical portion 1c of the barrel shaft. This auxiliary drive member 19 is connected on the one hand to the gear cover 1b by two diametrically opposite pins 20, on the other hand, to the ring 17 by two spring arms 19a whose ends are housed in two notches 17c of the ring 17.

With this auxiliary motor member 19, when the winding mobile 8 drives the shaft 1d of the cylinder 1 in the direction of the needles of the watch ( figure 4 ) to raise the barrel spring 6, the ratchet wheel 15 rotates in the opposite direction and therefore no longer causes the ring 17 through the pawls 16. Therefore, if we go up the barrel spring 6 then that the chronograph wheel is driven by the toothing 1b of the cylinder cover 1, there would be at this time more drive the chronograph train. To prevent this stop from occurring, it is the auxiliary drive member 19 that takes over. For this purpose, the pawl 18, engaged in the ratchet teeth 17b, retains the ring 17, allowing the spring arms 19a to relax by rotating the toothed lid 1b in the opposite direction to that of the clockwise at a maximum angle corresponding to that of the openings in arcs of circles 10. As soon as the reassembly ceases, the internal end of the mainspring spring 6 again causes the ratchet wheel 15 in the opposite direction to that of the needles of the watch, brings the tenons 9 in the position illustrated by the figure 4 and resets the springs 19a of the auxiliary drive member 19.

In addition to the kinematic chain formed by the chronograph wheel 4 between the first wheel 4a engaged with the toothed lid 1b and the last wheel 4f selectively engaged with the escapement wheel 2 of the chronograph, this kinematic chain which constitutes a gear wheel is extended by a wheel 4 'whose last mobile 4'c is, in this example, a lap in 20 seconds and carries a needle of a seconds counter, and a reset cam 24. Finally, a cog additional 4 "chronograph meshes directly with the toothing 1b of the cylinder cover 1 and leads, in this example, the last mobile 4" b of this wheel at a rate of one turn in 10 minutes. This mobile 4 "b also carries a hand of a minute counter, and a reset cam 25.

In both cases, the connection between the reset cams 24, 25 and the mobiles 4'c, respectively 4 "b is a friction coupling under the pressure of a spring 26 bearing on the frame B.

To selectively put the last wheel 4f of the kinematic chain of the chronograph train in engagement with the escapement wheel 2 of the chronograph mechanism, the wheel 4f has a groove 21 engaged with an elastic arm 22 fixed to the frame of the workpiece. watchmaking. This elastic arm 22 is flexible in a direction parallel to the axis of the last movable 4f of the chronograph train so that by bending, it can move the mobile 4f from the position of the figure 1.1 in which it is opposite and engaged with the escapement mobile 2 of the chronograph at the position of the figure 2.1 in which it is no longer in front of the escape wheel 2 of the chronograph and therefore more in contact with it. In addition, in this disengaging position of the mobile 4f, the elastic arm 22 presses the shaft of the mobile 4f against its lower bearing 34 ( figure 2.1 ) thus acting simultaneously as a braking member which stops the mobile 4f in the stop position and allows the reading on a dial not shown, the angular position of the indicator hand integral with the shaft of the mobile 4f . All the chronograph wheel 4, 4 ', 4 "being driven simultaneously, it is possible to read vis-à-vis the respective reading scales, the positions of the hands integral with the other mobiles 4'c, respectively 4" b, which gives the minutes seconds and hundredths of seconds of the measured time interval.

The various on / off control levers of the chronograph mechanism are those of a chronograph mechanism with column wheel 23 which constitutes the centralized control of the various levers. This column wheel 23 comprises a ratchet gear in engagement with a locating pawl 42 and with a drive pawl 27 articulated at the end of a rocker 28 manually controlled by a first chronograph pusher 29 accessible from the outside. outside as usual.

This column wheel controls three levers, the clutch lever and brake 30 subjected to the force of a return spring 41, the zero stop lever 31 of the mobile 4f making one revolution per second and the lever 32 of switching off the brake lever 30. It can be seen that the zeroing of the wheel 4f can not be obtained by means of a cam as usually and as in the case of the cams 24 and 25, but re-engaging the wheel 4f with the chronograph exhaust wheel 2. As can be seen in particular on the Figures 3 and 3.1 the wheel 4f is secured to a stop member 33 which has two diametrically opposed arms for balancing, but one of which extends beyond the outer diameter of the teeth of the wheel 4f. The angular position of the longer arm of the stop member 33 is in a position such that when the arm of the stop member 33 encounters the zero stop lever 31, the wheel 4f is in a angular position in which, the line of centers, joining the last mobile 4f of the first end of the chronograph wheel 4 to the chronograph exhaust wheel 2, passes halfway between two adjacent teeth of the mobile 4f, where none of these two teeth are not engaged with the chronograph escape wheel 2. The zero stop lever 31 is integral with a resilient flexible arm 31a bearing against a stop 35. This flexible arm is constantly exerting on this lever 31 a torque tending to turn it in the opposite direction to that of the clockwise and bring back its end in contact with the column wheel 23 in a space between two columns as soon as it is presented, as illustrated by the figure 1 .

As can be seen, the Figures 2 and 2.1 represent the chronograph mechanism in the off position, following the driving of the column wheel 23 one step from the running position illustrated by the Figures 1 and 1.1 . In this stopping position, the column wheel 23 has enabled the clutch and brake lever 30 to swing in the counterclockwise direction under the action of its return spring 41. This tilting stopped the wheel 4f by disengaging it from the chronograph escapement wheel 2 and immobilizing it by pressing its axis against the bearing 34, which makes it possible to measure the hundredth of a second, taking into account the fact that the needle second takes a turn in one second. During this same displacement of the column wheel 23, the zero stop lever 31 is moved clockwise so that its end is in the trajectory of the longest arm of the stop member 33 secured to the wheel 4f.

The zeroing of the wheel 4f which has just been described is controlled by a zero stop lever 31 under the control of a second reset pushbutton 37 which, thanks to the column wheel 23 can not be actuated only when the chronograph wheel 4 has been previously stopped, that is to say that it is in the position illustrated by the figure 2 . The reset mechanism controlled by the second pusher 37 comprises a lever 36 for disengaging a spring-loaded locking member 38 provided with a retaining pin 38a engaged with a lug 39a of a reset lever. 39 of the cams 24 and 25 ( figures 1 and 2 ). This reset lever 39 is subjected to the force of a spring 40. When the lugs 38a, 39a are no longer in engagement, the spring 40 drives the reset lever 39 in the direction of clockwise . During its angular displacement, the reset lever 39 drives the lever 32 to deactivate the brake lever 30 to return it to its clutch position of the wheel 4f with the chronograph exhaust wheel, as illustrated by the figures 1.1 and 3 .

Since when stopping the chronograph mechanism ( figure 2 ) the end of the zero stop lever 31 has been moved in the path of the longer arm of the stop member 33, the wheel 4f is stopped as soon as the longest arm meets the end of the lever 31, as illustrated by figure 3 .

Simultaneously, the two reset cams 24 and 25 are returned to the positions illustrated in FIG. figure 3 by the reset lever 39. The displacement of the lever 36 by the second pusher 37 is limited by a notch 32a formed on the lever 32, as illustrated by FIG. figure 3 . This limit position of the lever 32 engaged with the notch 32a lasts only as long as pressure is exerted on the pusher 37. As soon as this pressure ceases, the spring 38 returns to its initial position and returns the lever 36 to the position illustrated in FIGS. figures 1 and 2 .

The chronograph mechanism is ready to be restarted by pressing the first pusher 29. Note that when the chronograph mechanism is in the off position illustrated by the figure 2 it can either be reset by pressing the second push-button 37, or restarted by pressing the first push-button 29, in which case the column wheel returns to the position illustrated by FIG. figure 1 and the measured times add up.

Claims (7)

1. Chronograph comprising a first drivetrain between a drive spring (6) and an escapement associated with a regulator device, and a second drivetrain (4) of which a last runner (4f) of a first end is in selective desmodromic drive connection with the first drivetrain via a clutch device (22, 30) associated with a simultaneous braking member (34), characterized in that the first runner (4a) of the second end of the second drivetrain (4) is in direct connection with a drive spring (6), that the connection between the last runner (4f) of the first end of the second drivetrain and the first drivetrain (4) comprises a chronograph escapement wheel (2) that moves as one with a runner of the first drivetrain.
2. Chronograph according to Claim 1, in which the first drivetrain and the second drivetrain (4) are both in connection with a drive spring (6) situated at the centre of the chronograph movement.
3. Chronograph according to one of the preceding claims, in which the first drivetrain is connected to a first toothset (1a) of a drum (1) kinematically linked to the outer end of the drive spring (6), while the second drivetrain (4) is connected to a second toothset (1b) of the same drum (1) kinematically linked to the internal end of the same drive spring (6) via a one-way drive device (15-17).
4. Chronograph according to one of the preceding claims, in which the selective connection between the first drivetrain and the second drivetrain (4) comprises a second escapement wheel (2) that turns as one with the escape wheel of the first drivetrain and is in mesh with the last runner (4f) of the first end of the second drivetrain (4), and in that the clutch mechanism (22, 30) associated with a simultaneous braking member (34) is in mesh with the last runner (4f) of the first end of the second drivetrain (4).
5. Chronograph according to Claim 4, in which the ratio between the second escapement wheel (2) and the last runner (4f) of the first end of the second drivetrain is chosen so that this last runner (4f) of the first end of the second drivetrain (4) performs one revolution per second.
6. Chronograph according to Claim 4, in which the last runner (4f) of the first end of the second drivetrain (4) is pivot-mounted in two bearings with an axial play that is chosen so that it can occupy at least two axial positions, a first position in which its toothset is in mesh with a chronograph escapement wheel (2) secured to one of the runners of the first drivetrain, and a second position in which it is not in mesh with this chronograph escapement wheel (2), this last runner (4f) of the first end of the second drivetrain (4) moving as one in terms of axial movement with a clutch and braking member (30) which, in the said second position, presses a portion of the last runner (4f) against an axial abutment surface (34) with enough force to immobilize it.
7. Chronograph according to one of the preceding claims, in which a column wheel (23) is in mesh notably with a zero-stop lever (31) that can be moved by the column wheel (23) between a rest position and a stop position in which a stop element of this zero-stop lever (31) lies in the path of a stop arm (33) moving as one with this last runner (4f) of the first end of the second drivetrain (4), the stop position corresponding to a position in which the line of the centres joining the last runner (4f) of the first end of the second drivetrain (4) to the chronograph escapement wheel (2) passes midway between two adjacent teeth of the last runner (4f) of the first end of the second drivetrain (4) where neither of these two teeth is in mesh with the chronograph escapement wheel (2), so as to allow the chronograph escapement wheel (2) to turn without driving the last runner (4f) of the first end of the second drivetrain (4).

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