CH710463A2 - drive mechanism of a leaping body and timepiece including such a mechanism. - Google Patents

Abstract

The invention relates to a driving mechanism of a jumping member comprising a drive wheel (1), an indicator of a unit of time, a jumping member (6) integral with said indicator and coaxial with said drive wheel. drive (1) to which said jumping member (6) is coupled by a spring, a cam (12) arranged to tilt an anchor (20) in an oscillating motion to release the jumping member (6) once per unit of time. According to the invention the cam (12) and the jumping member (6) have distinct pivot axes, the drive mechanism further comprising an intermediate gear kinematically linking the drive wheel (1) to the cam (12). ), and the anchor (20) has four distinct arms (20a, 20b, 20c, 20d), two (20a, 20b) of the four arms constituting feelers arranged to cooperate with the cam (12) and the other two arms ( 20c, 20d) constituting exhaust arms arranged to successively block and release once per unit time the jumping member (6) alternately. The invention also relates to a timepiece comprising such a mechanism.

Description

Field of the invention

The invention relates to the field of mechanical watchmaking. It relates, more particularly, to a mechanism for driving a jumping member in a timepiece comprising a drive wheel arranged to rotate at a constant speed, an indicator of a unit of time, a jumping member integral with said indicator. and coaxial with said drive wheel to which said jumping member is coupled by a spring, a cam arranged to control an anchor, said cam having a profile arranged to tilt the anchor in an oscillating motion so as to release the member jumping once per unit of time. The present invention also relates to a timepiece comprising such a drive mechanism of a jumping member.

Background of the invention

When the drive wheel is one revolution per minute, the unit of time may be the second. The drive mechanism can then be a dead second mechanism, arranged to release the jumping member once per second. A dead second mechanism includes a dead second indicator, usually a large hand in the center of the dial, which is 1 leap per second and can usually be stopped without the watch stopping. These mechanisms are extremely complicated realization. However, they sometimes lack accuracy, the jumps taking place in some cases to 5/6 of a second. They are also very energy consumers.

Some of these mechanisms are powered by a second source of energy, specific to the second dead mechanism, in addition to the main source of energy, necessary for movement.

[0004] Other mechanisms are powered by the energy source of the movement, of the type described in the preamble. Such mechanisms are known to those skilled in the art and described for example in patent CH 311 865. In these mechanisms, the dead second cam comprises a large number of teeth (30), involving small angular steps, which makes the jumps very sensitive to the imperfections of the second dead cam. In addition, the same pallet of the dead second anchor is used both to cooperate with the dead second cam and the second wheel. The dead second anchor blocks the jumping member due to the force of the coupling spring and friction. This friction absorbs a relatively large power, so that the power consumption by the second dead mechanism is high.

Summary of the invention

The invention particularly aims to overcome the various disadvantages of known mechanisms.

More specifically, an object of the invention is to provide a mechanism for driving a jumping member, and in particular a dead second mechanism, reliable, allowing to have precise jumps at each unit of time, and especially every second.

The invention also aims to provide a drive mechanism of a jumping member, including a dead second mechanism, allowing a reduced power consumption, allowing the use of the same energy source than that of the movement.

For this purpose, the present invention relates to a drive mechanism of a jumping member comprising a drive wheel arranged to rotate at a constant speed, an indicator of a unit of time, a jumping member integral with said indicator and coaxial with said drive wheel to which said jumping member is coupled by a spring, a cam arranged to control an anchor, said cam having a profile arranged to tilt the anchor in an oscillating motion so as to release the jumping member once per unit of time.

According to the invention, the cam and the jumping member have separate pivot axes, said drive mechanism further comprising an intermediate gear kinematically linking the drive wheel to the cam, and the anchor has four distinct arms, two of the four arms constituting feelers arranged to cooperate with the cam and the other two arms constituting exhaust arms arranged to successively block and release once per unit time alternating jumping member.

Advantageously, the intermediate wheel may comprise an intermediate mobile formed of an intermediate gear arranged to cooperate with the drive wheel and an intermediate wheel arranged to cooperate with a cam drive wheel integral with the cam.

Preferably, the intermediate gear can be sized so that the cam comprises less than thirty teeth, each tooth having a forward ramp, and performs more than one revolution per minute.

Advantageously, according to an alternative embodiment, the time unit is the second, the drive wheel being arranged to make a turn in 60 seconds, and the indicator being a second dead indicator, the cam may comprise ten teeth and be arranged to perform three revolutions per minute, each tooth having a front ramp decomposing in six steps.

Preferably, the front ramp of each tooth of the cam has, on the last three steps of the tooth, a slope greater than the slope of the front ramp on the first three steps of the tooth.

Advantageously, the four arms of the anchor may be arranged to form substantially an X, the probe arm positioned to cooperate with the cam being disposed opposite to the pivot point of the Anchor to the exhaust arm positioned to release the jumping member.

The drive mechanism of a jumping member according to the invention allows to have precise jumps at each unit of time while allowing reduced energy consumption.

The present invention also relates to a timepiece comprising a watch movement provided with a finishing gear powered by a power source, and a drive mechanism of a jumping member as defined hereinbelow. above.

Advantageously, the drive wheel of the second dead mechanism can be powered by the energy source of the movement.

Preferably, the drive wheel may be the second wheel of the work train.

Brief description of the drawings

Other features and advantages of the invention will appear more clearly on reading the following description of a particular embodiment of the invention, given as a simple illustrative and non-limiting example, and the appended figures. , among: <tb> Figs. 1 to 4 <SEP> represent a top view of a dead second mechanism according to the invention, the second dead anchor occupying different positions according to the steps of a tooth of the dead second cam, and <tb> fig. <SEP> represents a view of the tooth profile of the dead second cam.

Detailed description of a preferred embodiment

The following description relates to an embodiment of the invention for which the unit of time is the second. The drive mechanism then constitutes "a dead second mechanism", and will be referred to below as this expression.

Referring to FIG. 1, the second dead mechanism according to the invention is integrated in a mechanical timepiece, comprising a watch movement provided with a finishing gear powered by a power source, such as a cylinder. The finishing gear train traditionally comprises a second wheel 1 comprising 60 teeth and arranged to turn in 60 seconds. The movement also traditionally includes an escape pinion 2 and an escape wheel 3 as well as an escapement anchor and a pendulum. These elements are known to those skilled in the art and do not require a detailed description. Note however that the frequency of the balance is advantageously chosen at 3 Hz, as will be understood below.

The dead second mechanism comprises a drive wheel constituted more specifically here by the second wheel of the finishing gear.

The second dead mechanism also comprises a jumping member 6, such as a wheel, secured to a second dead indicator, such as a needle (not shown). The jumping member 6 is mounted loosely on the axis of the second wheel 1, so that the jumping member 6 is coaxial with the second wheel 1 and not integral with the latter. The jumping member 6 is elastically connected to the second wheel 1 by means of a spiral spring 8, driven on the second wheel 1. The jumping member 6 is a wheel comprising 30 teeth and making a turn in 60 seconds.

The dead second mechanism also comprises a dead second cam mobile formed of a cam drive wheel 10 and a dead second cam 12, integral with said cam drive wheel 10. The cam drive wheel 10 is arranged to cooperate with the exhaust pinion 2.

According to the invention, the second wheel 1 and the cam driving wheel 10 are pivotally mounted on the frame of the movement so as to have separate pivot axes, so that the dead second cam 12 and the jumping member 6 (or second wheel 1) are not coaxial.

In addition, the second wheel 1 and the cam drive wheel 10 are connected kinematically by an intermediate gear, and more particularly an intermediate mobile comprising an intermediate gear 14 meshing with the second wheel 1 and an intermediate wheel 16, integral with said intermediate gear 14, and meshing with the cam driving wheel 10. The dimensions and the number of teeth of the intermediate movable are provided such that the cam driving wheel 10 and the dead second cam 12 make one turn per 20 seconds, ie 3 revolutions per minute, the cam drive wheel 10 comprising 66 teeth and the dead second cam 12 comprising 10 teeth 18.

The dead second mechanism also comprises a second dead anchor 20 pivotally mounted at a pivot point A on the movement frame, and controlled by the dead second cam 12 to release and blow the jumping organ once. per second. The jumping member thus constitutes a dead second escape wheel.

According to the invention, the dead second anchor 20 comprises four separate arms 20a, 20b, 20c and 20d. The end of each arm acts as a pallet. In the following description, the term "pallet" is used to designate the end of an arm 20a, 20b, 20c and 20d, the pallet thus forming a single piece with the corresponding arm. Advantageously, the second dead anchor 20 is monobloc and made by LIGA. The upper arm 20a and the lower arm 20b constitute upper and lower probes arranged to cooperate with the dead second cam 12. The upper arm 20c and the lower arm 20d constitute upper and lower exhaust arms arranged to successively block and release once a second, the jumping member 6 alternately. The four arms 20a, 20b, 20c and 20d are positioned relative to the pivot point A so as to form substantially an X, the end of each arm being bent to cooperate with either the dead second cam 12 or with the Jumping member 6. The arms 20a, 20b, 20c and 20d work in opposition to the pivot point A. For example, as shown in FIG. 1, the upper feeler arm 20a is positioned to be controlled by the tooth profile 18 of the dead second cam 12 while the exhaust arm opposite from the pivot point A, namely the lower exhaust arm. 20d, is positioned to release the jumping member 6.

Each tooth 18 of the second dead cam 12 has a profile defined by a ramp before 18a, the functional portion of the tooth on which the end or the pallet of the feeler arms 20a, 20b rubs, and a reverse 18b . Advantageously, the frequency of the balance is chosen at 3 Hz (or 6 alternations per second) so that each front ramp 18a can be decomposed into six steps, each step corresponding to a rotation angle of 3 ° of the cam second dead. A displacement along the front ramp 18a of a tooth 18 corresponding to a rotation angle of 18 ° of the second dead cam. In order to have a precise jump, the front ramp 18a of each tooth 18 has a slope which is higher on the last three steps corresponding to a rotation angle of the second dead cam between 9 ° and 18 °, ie at moment close to the jump, that on the first three steps corresponding to an angle of rotation of the dead second cam between 0 ° and 9 °. As shown more precisely in FIG. 5, determining that at the origin of the tooth, for an angle of 0 ° the height is equal to 0, and that the total height of the tooth h corresponds to an angle of rotation of 18 ° of the second cam the height of the tooth corresponding to the first third step, ie a rotation angle of 9 ° of the dead second cam, is between 10% and 15% of the height h, and the height b of the corresponding tooth in the fifth step, a rotation angle of 15 ° of the dead second cam, is between 55% and 60% of the height h.

The profile of the reverse 18b avoids the premature jump of the dead second anchor. This profile is the result of the profile of the front ramp 18a, so that when the pallet of one of the feeler arms is in contact with the front ramp 18a of a tooth 18 of the dead second cam 12, a constant clearance is maintained between the dead second cam 12 and the passive pallet of the other probe arm (that is to say the pallet of the probe arm which is not in contact with the ramp before a tooth).

The operation of the second dead mechanism is as follows: with reference to FIGS. 1 to 5, the second wheel 1 drives the intermediate gear 14 and thus the intermediate wheel 16, which in turn drives the cam drive wheel 10 and thus the dead second cam 12. Said dead second cam 12, turning allows the front ramp 18a of a tooth 18 to act on the pallet of the upper arm 20a of the dead second anchor 20, so that said anchor 20 tilts around its pivot point A to pull out, in contrast, the pallet of the lower exhaust arm 20d of the second dead anchor 20 of the toothing of the jumping member 6.

More specifically, between the step 0, shown in FIG. 1, and the fifth step of the front ramp 18a of the tooth concerned (ie for a rotation angle of the dead second cam 12 of 15 °, see Fig. 5), the pallet of the lower exhaust arm 20d does not not out of the toothing of the jumping member 6, regardless of the play catch. The asymmetric profile of each tooth 18 of the dead second cam 12 is such that the lifting of the anchor is done progressively with the pallet of the upper probe arm 20a while the pallet of the lower probe arm 20b descends without touching the dead second cam 12.

When the pallet of the upper probe arm 20a arrives at the fifth step of the ramp before 18a, as shown in FIG. 2, the jumping member 6 has not yet jumped, and is still blocked by the pallet of the lower exhaust arm 20d. Once the pallet of the upper probe arm 20a has arrived at the fifth step of the ramp before 18a, if the dead second anchor 20 undergoes a catch of play following a shock for example, the pallet of the lower probe arm 20b is positioned at the contact 18b of the corresponding tooth 18 of the dead second cam 12, as shown in FIG. 3. Even in this configuration, the jumping organ 6 has not jumped, but remains at the limit of jumping. The jumping member 6 jumps when the pallet of the upper feeler arm 20a moves between the fifth and sixth steps. When the pallet of the upper arm 20a reaches the sixth step of the ramp before 18a, as shown in FIG. 4, jumping organ 6 jumped. With the dead second anchor tilted, the lower exhaust arm pad 20d disengaged from the jumping member 6 and released it. The jumping member 6, recalled by the spiral spring 8 attached to the second wheel 1, rotates 6 °, either a progress or a jump of one second of the second dead indicator. The jumping member is then again blocked this time the pallet of the upper exhaust arm 20c, on which it is held in support by the spiral spring 8, as shown in FIG. 4. This is the pallet of the lower probe arm 20b, opposite to the pivot point A, which will come into contact with the front ramp 18a of a tooth of the second dead cam 12, to switch the second dead anchor 20 in the other direction and again release the jumping organ. Thus, the movement of the dead second anchor is a reciprocating movement that releases, tooth by tooth, the jumping member 6, once with the pallet of the upper exhaust arm 20c, then with the pallet of the arm lower exhaust 20d, successively and alternately. As a result, the dead second indicator advances in increments of 1 second.

The dead second mechanism of the invention allows for precise jumps every second with lower power consumption. Indeed, the mechanism of the invention is powered by the same source of energy as the finishing gear. A second source of energy is not necessary. Furthermore, the arrangement on separate axes of the jumping member and the dead second cam provides for optimized shapes for the vanes of the exhaust arms on the one hand and for the pallets of the feeler arms on the other hand , in connection with optimized shapes of the teeth of the dead second cam. The energy consumption due to the spiral spring between the second wheel and the jumping member is almost zero. In particular, the higher the slope of the front ramp of the teeth of the second dead cam will be high on the last three steps of the tooth, the more the jump will be marked and therefore accurate. A lower slope on the first three steps of the tooth makes the angular pitch of the second dead anchor relatively low over this period. The torque consumption is therefore low. The slope on the last three steps is on the contrary more important but must however remain measured in order to avoid over-consumption of torque on the mobile cam second dead. As a result, the angular pitch of the dead second anchor is higher on the last three steps, which allows the jump to be performed over a larger measurement range, and consequently increases the jump accuracy. In addition, the use of a dead second cam having only 10 teeth makes it possible to obtain larger angular steps, and thus less imperceptible jumps in the dead second cam.

All the parts of the dead second mechanism directly related to the second dead indicator are recessed, this in order to lighten them to the maximum and reduce inertia and torque consumption. Moreover, these recesses make it possible to balance the parts, in order to obtain an imbalance close to zero.

Furthermore, the radius forming the flank of the toothing of the jumping member is chosen to be concentric and equal to that of the dead second anchor with which it is in contact. As a result, when the dead second anchor tilts, the jumping member does not move, which ensures the stability of the second dead indicator.

Finally, the arrangement on separate axes of the jumping member and the dead second cam allows not to add a large number of parts on the same axis and therefore to limit the accumulation of tolerances and the misalignment of mobile, unlike the coaxial mechanisms of the prior art. The precision on the axis of the jumping member is therefore greater while simplifying the assembly of parts.

It is obvious that the second dead mechanism described above can be adapted to another unit of time than the second. Thus, the drive mechanism of a jumping member according to the invention can be adapted to the display of any unit of time: second, minute, ten seconds, ten minutes, etc. To do this, the skilled person knows how to adapt accordingly the number of teeth on the cam and the jumping member, as well as the gear ratios in the gear train.

Claims (9)

1. Mechanism for driving a member jumping in a timepiece comprising a drive wheel (1), an indicator of a unit of time, a jumping member (6) integral with said indicator and coaxial with said wheel drive (1) to which said jumping member (6) is coupled by a spring, a cam (12) arranged to control an anchor (20), said cam (12) having a profile arranged to tilt the anchor ( 20) in an oscillating motion so as to release the jumping member (6) once per unit of time, characterized in that the cam (12) and the jumping member (6) have distinct pivot axes, said mechanism driving device further comprising an intermediate gear kinematically linking the drive wheel (1) to the cam (12), and in that the anchor (20) has four arms (20a, 20b, 20c, 20d) separate, two (20a, 20b) four arms constituting probes arranged to cooperate with the cam (12) and the two other arms (20c, 20d) constituting exhaust arms arranged to successively block and release once per unit time the jumping member (6) alternately. 2. Mechanism according to claim 1, characterized in that the intermediate gear comprises an intermediate mobile formed of an intermediate gear (14) arranged to cooperate with the drive wheel (1) and an intermediate wheel (16) arranged to cooperate with a camming wheel (10) integral with the cam (12). 3. Mechanism according to any one of the preceding claims, characterized in that the intermediate gear is dimensioned so that the cam (12) comprises less than thirty teeth (18), each tooth (18) having a front ramp (18a), and performs more than one revolution per minute. 4. Mechanism according to any one of the preceding claims, characterized in that, the unit of time being the second, the drive wheel (1) being arranged to make a turn in 60 seconds, and the indicator being a dead second indicator, the cam (12) comprises ten teeth (18) and is arranged to perform three revolutions per minute, each tooth (18) having a front ramp (18a) decomposing in six steps. 5. Mechanism according to claim 3 or 4, characterized in that the front ramp (18a) of each tooth (18) of the cam (12) has, on the last three steps of the tooth (18), a slope greater than the slope of the front ramp (18a) on the first three steps of the tooth (18). 6. Mechanism according to any one of the preceding claims, characterized in that the four arms (20a, 20b, 20c, 20d) of the anchor (20) are arranged to form substantially an X, the probe arm (20a , 20b) positioned to cooperate with the cam (12) being oppositely disposed with respect to the pivot point of the anchor (20) at the exhaust arm (20c, 20d) positioned to release the jumping member (6) . 7. Timepiece comprising a watch movement provided with a finishing gear powered by a power source, characterized in that it comprises a drive mechanism of a jumping member according to any one of claims 1 to 6. 8. Timepiece according to claim 7, characterized in that the drive wheel (1) is powered by the energy source of the movement. 9. Timepiece according to claim 7 or 8, characterized in that the drive wheel (1) is the second wheel of the work train.