EP3349072B1 - Mechanism for timepiece comprising a cam and a finger - Google Patents

Description

Technical area

The present invention relates to a mechanism for a timepiece comprising a cam and a feeler.

State of the art

We know in the state of the art of watch movements to choose the direction of rotation of a display member, for example to select a chronograph or countdown function.

An example of such a mechanism is described for example in the patent application EP3026506A1 . The selection mechanism comprises a rocker controlling an actuator for engaging or disengaging it from one or more notches formed in the periphery of a cam.

WO02 / 077725 describes a chronograph comprising counters capable of rotating in both directions and provided with a control finger capable of engaging on a transmission wheel.

Such mechanisms thus frequently include a feeler which can be actuated to fall into or out of a notch provided in the periphery of a cam. However, sometimes the probe falls on the edge of the cam instead of falling in the notch.

To reduce this risk, it is necessary to reduce the size of the probe head to allow it to penetrate more easily into the notch. The play thus created between the probe and the notch causes however, an imprecision on the angular positioning of the cam and of the indicator actuated by this cam.

US3696609 describes a mechanism with a snail-shaped cam and a feeler, the end of which is pressed against the periphery of the cam by elastic means. The probe can be raised to turn the cam in the opposite direction when setting the time. The probe is never engaged in a notch and raising the cam, or lowering it, does not pose any particular difficulty.

However, mechanisms are known which require a cam with a narrow notch, provided with two edges and a bottom, the end of the probe of which can only be extracted by pivoting the cam. The notch must be wide enough to allow easy insertion or extraction of the end of the probe, even if this end is not exactly positioned opposite the notch. An excessively wide notch, however, poses the problem of imprecise positioning of the end of the probe at the bottom of the notch.

Brief summary of the invention

An object of the present invention is to provide a mechanism free from the above limitations.

In particular, an object of the invention is to provide a mechanism comprising a cam with a notch and a feeler which can be raised or fallen more easily into the notch.

An object of the invention is in particular to propose a mechanism comprising a cam with a notch having two edges and a bottom, and a finger which can be raised or extracted easily from this notch.

An object is also to precisely control the position of the finger against the cam both when the finger is in abutment against the periphery of the rotating cam, and when it is at the bottom of the notch.

• une came dont la périphérie présente une encoche;
• un palpeur comportant un bras muni d'un axe de rotation et une tête de palpeur munie d'un doigt agencé pour palper ladite périphérie, et pour tomber dans l'encoche lorsque celle-ci se retrouve en face du doigt du palpeur;
• le palpeur pouvant pivoter autour de l'axe de rotation de manière à placer le doigt soit dans une première position appuyée contre ladite périphérie de la came, soit, en relevant le palpeur, dans une seconde position à distance de ladite came,
• le doigt étant monté sur le palpeur de manière à ce que son extrémité puisse se déplacer dans un premier sens par rapport au palpeur sous l'effet de la force de réaction exercée par ladite périphérie de la came lorsque le doigt est appuyé contre cette came mise en rotation,
• un élément flexible étant prévu pour déplacer l'extrémité du doigt par rapport au palpeur dans un deuxième sens opposé au premier sens lorsque le doigt n'est pas en appui contre la périphérie de la came,
• le mécanisme étant agencé de manière à ce que l'élément flexible déplace l'extrémité du doigt dans le deuxième sens par rapport au palpeur également lorsque le doigt est dans l'encoche.

According to the invention, these aims are achieved in particular by means of a mechanism for a timepiece, comprising:

• a cam whose periphery has a notch;
• a feeler comprising an arm provided with an axis of rotation and a feeler head provided with a finger arranged to feel said periphery, and to fall into the notch when the latter is found in front of the feeler's finger;
• the probe being able to pivot about the axis of rotation so as to place the finger either in a first position pressed against said periphery of the cam, or, by raising the probe, in a second position at a distance from said cam,
• the finger being mounted on the feeler so that its end can move in a first direction relative to the feeler under the effect of the reaction force exerted by said periphery of the cam when the finger is pressed against this put cam in rotation,
• a flexible element being provided for moving the end of the finger relative to the probe in a second direction opposite to the first direction when the finger is not in abutment against the periphery of the cam,
• the mechanism being arranged so that the flexible element moves the end of the finger in the second direction relative to the probe also when the finger is in the notch.

The flexible element allows the end of the finger to move (by deformation of the finger, and / or by displacement of the whole finger) between a first position and a second position, so as to penetrate more easily into the notch.

The mechanism may include means for placing the finger in a first position pressed against the periphery of the cam or for raising it. To this end, the mechanism may for example include a first actuator, for example a jumper, for placing the finger in a first position pressed against the periphery of the cam, and a second actuator, for example a hook, for placing the finger in a second raised position at a distance from this cam.

The probe has an axis of rotation to allow it to rotate between the first and second positions, and vice versa. The elastic portion can be arranged to modify the distance between the finger and this axis of rotation.

The elastic portion can be arranged so that the distance between the end of the finger and the axis of rotation is greater when the probe is in the first position than when the probe is in the second position.

The finger can constitute a separate part from the probe arm and assembled on this arm, for example by driving out, clipping or gluing. This allows the finger and the arm to be produced separately, for example with separate manufacturing steps and / or materials, or in different thicknesses.

In one embodiment, the elastic portion is integrally linked to the finger. This reduces the number of parts and assembly operations.

A separate elastic portion of the finger can also be envisaged, for example an elastic portion linked to the arm, or an independent elastic portion.

In one embodiment, the probe arm may have an opening. The elastic portion of the finger can be engaged in this opening, so that the finger can move between a first position pressed against an edge of the opening forming a first stop, and a second position pressed against the opposite edge of the opening forming a second stop.

The elastic portion can be arranged to force the finger against the second stop when the finger is free. In this second position, the deformation of the feeler allows the finger to penetrate more easily into the notch.

In the first pressed position, the deformation of the elastic portion of the feeler by the cam allows the finger to press against the first stop, by exerting an elastic force against this stop.

The probe can include an arm and a probe head provided with the finger.

The invention is in particular suitable for cams provided with a notch having two edges and a bottom.

In a preferred embodiment, the finger can only be raised from the notch by raising the probe.

The finger is arranged to fall almost instantly back into the notch when it is in the pressed position opposite the notch, and not to fall into the notch when it is in the raised position.

The finger can therefore fall into the notch either following a rotation of the cam, bringing the notch opposite the pressed finger; either following a movement of the finger passing from the raised position to the pressed position opposite the notch.

"Almost instantly" means in this context that the fall of the finger into the notch occurs without an intermediate step; in the pressed position, the finger can therefore either be pressed against the periphery of the cam, either against an edge of the notch. A stable state in an intermediate depth of the notch, without contact with an edge, is therefore excluded.

One of the edges of the notch is preferably flared in order to facilitate the introduction and / or extraction of the finger.

The cam and the finger are preferably arranged so that the finger does not come into contact with the bottom of the notch when the finger is in the notch.

In a preferred embodiment, the finger is pressed by the flexible element only against one of the edges of the notch, preferably against the flared edge of the notch, when it is in the notch.

Brief description of the figures

• La figure 1 illustre le mécanisme de l'invention dans une première position, le doigt étant appuyé contre la périphérie de la came.
• La figure 2 illustre le mécanisme de l'invention dans une troisième position, le doigt étant appuyé au fond de l'encoche sur la périphérie de la came.
• La figure 3 est un agrandissement de la figure 2, montrant le doigt et l'encoche.
• La figure 4 illustre le mécanisme de l'invention dans une seconde position, le doigt étant relevé à distance de la périphérie de la came.

Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

• The figure 1 illustrates the mechanism of the invention in a first position, the finger being pressed against the periphery of the cam.
• The figure 2 illustrates the mechanism of the invention in a third position, the finger being pressed at the bottom of the notch on the periphery of the cam.
• The figure 3 is an enlargement of the figure 2 , showing the finger and the notch.
• The figure 4 illustrates the mechanism of the invention in a second position, the finger being raised away from the periphery of the cam.

Example (s) of embodiment of the invention

The mechanism illustrated by way of example in different positions on the figures 1 to 4 comprises a cam 1 mounted on the same axis 12 as a toothed mobile 13, for example a wheel or a pinion. In one embodiment, the mobile 13 is part of the gear train of a watch movement, for example of the train of a countdown mechanism. The mobile 13 can for example drive a barrel 10 with which the needle or the minute disc is integral with a countdown indicator, for example a minute counter for a regatta watch.

The direction of rotation of the mobile 13 depends on the operating mode; in the example illustrated, this mobile rotates clockwise during the countdown, and does not rotate in chronograph mode.

The invention can also be applied to other horological complications implementing a cam with a notch and a feeler, for example to a striking watch.

The periphery 11 of the cam 1 has a notch 10. The notch is concave and has two edges 101, 102 + 103, one of which is flared, and a bottom. The edges are separated from the bottom by an edge. A feeler 5 provided with a finger 50 can be pressed against this periphery 11 using a jumper not shown, in position A illustrated on the figure 1 and in position C illustrated on the figures 2 to 3 , or raised at a distance from this periphery in position B illustrated on the figure 4 .

An unrepresented star can also be mounted on the axis 12, which makes it possible to index the cam 1 to place it in predetermined angular positions when a jumper not shown is pressed against this star. One of these predetermined positions allows for example to place the notch 10 in front of the finger 50, to facilitate its penetration into the notch.

One of the edges 101 of the notch 10 is practically rectilinear and perpendicular to the bottom of the notch while the other edge 102 is more flared.

The probe 5 can pivot around the axis of rotation 52. The mentioned jumper makes it possible to rotate the arm 5 around the axis 52 to press it against the periphery 11 in position A.

In one embodiment, position A corresponds to a countdown position. Position C corresponds to a chronograph counting position. Position B can correspond to a reset position for the hands or the chronograph indicator disc. A hook (not shown) grips the portion 540 of the end 54 of the feeler in order to raise it in position B by rotating it around the axis 52. When this hook is released, the feeler drops back into positions A or C pressed against the periphery 11, under the action of a jumper not shown. This hook can be released by a push button not shown, for example a start button of the chronograph.

The probe 5 has an arm 53 and an end opposite to the axis of rotation 52 and constituting a probe head. An oblong opening 55 formed in the probe head makes it possible to retain the finger 50. In this embodiment, the finger 50 therefore consists of a component separate from the arm 53 of the probe, and is assembled to this arm.

The assembly is carried out by driving out or gluing a stud 510 integrated into the finger 50 in the opening 55. The stud is mounted at the end of a flexible portion 51 between the stud 510 and the body 511 of the finger, including the end of the finger 512 engaged in the notch 10.

In the free position illustrated on the figure 4 , that is to say when the probe 5 is raised at a distance from the periphery 11, the flexible portion 51 exerts prestress on the head 511 and the end 512 of the finger 50, so as to pivot this end 512 in clockwise (in direction of the center of rotation 52) and pressing it against a stop 531 formed on the edge of the opening 55 closest to the axis of rotation 52. This prestressed position makes it possible to move the end 512 away from the finger intended to be engaged in the notch of the straight edge 101 of the cam, and to facilitate its introduction into the notch from the position illustrated on the figure 4 , for example when starting a chronograph directly from reset position B.

When finger 5 slides on the periphery 11 of cam 1 rotating in the z direction (here clockwise), in the position illustrated on the figure 1 , the reaction force exerted by this periphery against the support of the finger 50 rotates this finger in a first direction (counterclockwise) relative to the axis of rotation 56 of the finger 50. Indeed, the torque exerted by this reaction force, and / or by the friction force, opposes and is greater than the moment of force around this axis of rotation 56 due to the prestress exerted by the flexible portion 51 on the finger 50. The finger 50 is then pushed back against a second stop 530 formed on the edge of the opening 55 farthest from the axis of rotation 52.

When the notch 10 reaches opposite the finger 50, the latter drops almost instantaneously to the bottom of the notch, by suddenly pivoting around the axis 52 under the effect of the jumper not shown. The figures 2 and 3 show the position of the finger 50 after its introduction into the notch 10.

When it reaches the bottom of the notch, the finger 50 is released from the reaction force exerted by the periphery 11 of the cam 1, and returns to its position pressed against the stop 531 under the effect of the prestress created by the flexible portion 51, leaving a clearance 100 between the head of the finger 512 and the edge 101. The distance between the end of the finger and the axis of rotation 52 therefore changes when the finger enters the notch under the effect from the jumper from position A.

The figure 4 illustrates the mechanism with a push-button in position B raised. In the case of a chronograph, this position is reached for example by actuating the reset button of the chronograph hands. In the case of a device combining a chronograph and a countdown, this position can for example also be obtained during the setting of the countdown.

By pressing the start button from this position, the probe 5 drops back to position A or C (corresponding to figures 2 and 3 ) bearing against the periphery 11 of the cam 1, and, to reach position C, the finger 50 enters the notch 10 under the action of the jumper mentioned above. From this position, the action of the elastic portion 51 tends to move the end of the finger 50 away from the edge 101, in order to facilitate its penetration.

Reference numbers used in the figures

1

Cam

10

Notch

100

Clearance between the finger and the first edge 101 of the notch

101

First edge of the notch

102

Second edge of the notch

103

Flared edge of the notch

11

Cam periphery

12

Axis

13

Toothed mobile

5

Feeler

50

Probe finger (or beak)

51

Elastic portion

510

Plot

511

Finger body

512

Tip of the finger can be inserted into the notch

52

Rotation axis

53

Arms

530

First stop in the arm

531

Second stop in the arm

54

Probe head

55

Opening in the probe arm

56

Finger rotation axis

z

Direction of rotation of cam 1 during countdown

AT

First position (pressed)

B

Second position (free)

VS

Third position (finger engaged in the notch)

Claims (15)

1. Mechanism for a timepiece, having:

   a cam (1), the periphery (11) of which has a notch (10) ;

   a feeler (5) having an arm (53) provided with a rotation axis (52) and a feeler head (54) provided with a finger (50) designed to feel said periphery, and to drop into the notch (10) when the latter is located next to the finger of the feeler;

   the feeler (5) being able to pivot about the rotation axis (52) so as to position the finger either in a first position (A) pressed against said periphery (11) of the cam or, by lifting the feeler, in a second position (B) away from said cam,

   the finger being mounted on the feeler such that its end can move in a first direction with respect to the feeler under the effect of the reaction force exerted by said periphery of the cam when the finger is pressed against this cam set in rotation,

   the mechanism also having a flexible element (51) provided to move the end of the finger with respect to the feeler in a second direction opposite to the first direction when the finger is not pressed against the periphery of the cam,

   the mechanism being designed such that the flexible element (51) also moves the end of the finger in the second direction with respect to the feeler when the finger is in the notch.
2. Mechanism according to Claim 1, wherein said feeler (1) comprises said flexible element (51).
3. Mechanism according to Claim 1 or 2, wherein the distance between the end of the finger and said rotation axis (52) changes when the finger passes into the notch.
4. Mechanism according to one of Claims 1 to 3, wherein the finger can only be lifted out of the notch by lifting the feeler.
5. Mechanism according to one of Claims 1 to 4, wherein said elastic portion (51) is joined integrally to the finger (50).
6. Mechanism according to one of Claims 1 to 5, wherein said elastic portion (51) makes it possible to change the distance between the end of the finger (50) and said rotation axis (52).
7. Mechanism according to one of Claims 1 to 6, wherein the feeler (5) has an opening (55) with a first end stop (530) on one side of the opening and a second end stop (531) on the opposite side of the opening, the elastic portion (51) being inserted into said opening (55) such that the finger (50) can move between a first position (A) pressed against the first end stop and a second position (B) pressed against the second end stop (531).
8. Mechanism according to Claim 7, wherein the elastic portion (51) is designed to urge the finger (50) against the second end stop (531) when the finger is free.
9. Mechanism according to either of Claims 7 and 8, wherein the friction of the finger (50) against said periphery makes it possible to push the finger back against the first end stop (530).
10. Mechanism according to one of Claims 4 to 9, wherein said elastic portion (51) is designed such that the distance between the finger (50) and the rotation axis (52) is greater when the feeler is in the first position than when the feeler is in the second position.
11. Mechanism according to one of Claims 1 to 10, wherein the notch (10) has two edges (101; 102+103) and a bottom.
12. Mechanism according to Claim 11, wherein one of the edges (103) of the notch (10) is flared.
13. Mechanism according to either of Claims 11 and 12, which is designed such that the finger (50) is not in contact with the bottom of the notch (10) when it is in the notch.
14. Mechanism according to Claim 13, which is designed such that the finger (50) is pressed only against one of the edges (102+103) of the notch (10) by the flexible element (51) when it is in the notch.
15. Mechanism according to Claim 14, which is designed such that the finger (50) is pressed only against a flared edge (102+103) of the notch (10) by the flexible element (51) when it is in the notch.

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