CLOCK MOVEMENT WITH CLUTCH

Description

[0001] The present invention relates to a watch movement comprising a clutch device, in particular a clutch device enabling the starting and stopping of a chronograph.

[0002] In classic chronographs, a clutch lever carries a clutch wheel that continuously meshes with a chronograph drive wheel, also known as a field wheel, which is part of the seconds wheel assembly in the finishing gear train. When the clutch lever is engaged, the clutch wheel meshes with a chronograph wheel to transmit the rotation of the seconds wheel, thus rotating a chronograph hand carried by the chronograph wheel. When the clutch lever is disengaged, the clutch wheel is not meshing with the chronograph wheel, and the latter is held stationary by a brake or a hammer.

[0003] In this type of mechanism, the chronograph wheel rotates in the same direction as the seconds wheel, allowing the chronograph hand to rotate clockwise. However, there are situations where it is necessary to rotate the chronograph hand in the opposite direction to the seconds wheel. This is the case, for example, with double-sided watches where the hours, minutes, and seconds of the time measured by the movement are displayed on one side of the watch, with the seconds displayed off-center by a small hand attached to the seconds wheel, and where the chronograph hand, centered, is visible on the opposite side. In such cases, a linkage must be added between the seconds wheel and the clutch wheel, or between the clutch wheel and the chronograph wheel.Unlike the finishing gear train, which is always under tension, such a mechanism, like the clutch wheel, has backlash that will affect the chronograph's display accuracy. This backlash can be eliminated by a backlash compensation wheel, but this complicates the mechanism. The backlash can also be eliminated by adding friction, but with detrimental consequences in terms of wear. Document CH 714 798 A1 shows a chronograph with a two-wheel clutch mechanism.

[0004] These problems are also encountered in contexts other than that of a chronograph, for example in watch movements where the finishing gear controls an animation via a clutch, an animation which one wishes to rotate in the opposite direction to the direction of rotation of the moving part of the finishing gear which controls it.

[0005] The present invention aims to solve the aforementioned problems and proposes to this end a watch movement comprising a power source, a finishing gear, an escapement connected to the power source by the finishing gear, a resonator cooperating with the escapement, a driven wheel, a clutch rocker and a clutch wheel controlled by the clutch rocker to, in an engaged position of the clutch rocker, mesh with the driven wheel in order to transmit to the driven wheel the rotation of the finishing gear and, in a disengaged position of the clutch rocker, be out of contact with the driven wheel, characterized in that the clutch wheel is part of a wheel of the finishing gear.

[0006] The present invention further proposes a timepiece, such as a pocket watch, a pendant watch, a wristwatch or a clock, comprising such a clock movement.

[0007] Other features and advantages of the present invention will become apparent from the following detailed description, made with reference to the accompanying drawings, in which: there figure 1 is a block diagram of a clockwork movement according to the invention; the figure 2 is a top view of a part of the clockwork mechanism according to the invention; the figure 3 is a cross-sectional view of a part of the watch movement according to the invention.

[0008] With reference to the figure 1 , a watch movement 1 according to a particular embodiment of the invention, for a timepiece such as a pocket watch, a pendant watch, a wristwatch or a clock, comprises an energy source 2 consisting for example of one or more barrels, a finishing gear 4, an escapement 6 connected to the energy source 2 by the finishing gear 4 and a resonator 8, such as a balance wheel and hairspring or a resonator with flexible guidance, the oscillations of which are maintained by the escapement 6.

[0009] In addition to the escapement 6, the finishing gear train 4 drives a current time display 10 visible through a first crystal of the timepiece. The current time display 10 consists of hour, minute, and second hands associated with a first dial, the seconds hand being a small hand offset from the first dial and the watch movement 1.

[0010] The finishing gear 4 also drives, on demand, a chronograph mechanism 12 which controls a chronograph display 14. This display includes a chronograph hand indicating the chronograph seconds and optionally counter hands indicating the chronograph minutes and hours, this hand or these hands cooperating with a second dial. The chronograph display 14 is visible through a second crystal of the timepiece located on the opposite side of the timepiece from the side receiving the first crystal.

[0011] The finishing gear 4 comprises a center gear meshing with the power source 2, an intermediate gear meshing with the center gear, and a second gear meshing with the intermediate gear and with the escapement pinion of the escapement 6. At the figure 2 The average speed wheel, designated 16, and the seconds wheel, designated 18, are shown. The seconds wheel 18 carries the seconds hand, designated 20. The hour and minute hands are driven by the central wheel in the traditional manner. The chronograph hand, designated 22, is carried by a chronograph wheel 24 located at the center of the watch movement 1; this chronograph wheel 24 drives, if necessary, a minute counter which in turn drives an hour counter.

[0012] As shown in the figure 3 The seconds wheel 18 comprises, in a conventional manner, a shaft 26 to which a seconds wheel 28 and a seconds pinion 30 are attached. The seconds wheel 28 meshes with the escapement pinion. The seconds pinion 30, in turn, meshes with the wheel of the intermediate wheel 16.

[0013] The watch movement 1 is mounted in a frame classically comprising a plate 32 and bridges (not shown) fixed to the plate 32. The plate 32 is on the side of the current time display 10 and the bridges on the side of the chronograph display 14.

[0014] In the present invention, the shaft 26 of the seconds wheel 18 pivots on one side in a fixed part, namely, in the illustrated example, in a tube 34 fixed to the plate 32, and on the other side in a clutch rocker 36 mounted pivotally relative to the plate 32 about an axis B which is distinct from the axis A of the shaft 26 of the seconds wheel 18. In addition, the shaft 26 of the seconds wheel 18 carries a clutch wheel or field wheel 38 integral with the wheel and the seconds pinion 28, 30.

[0015] The stones 40 and 42, which serve as bearings for the shaft 26 (mounted respectively at the end of the tube 34 and in the clutch rocker 36), preferably have a swaged hole. In an alternative, the shaft 26 could pivot directly in the plate 32 rather than in a tube 34.

[0016] The clutch rocker arm 36 is acted upon by a return spring (not shown) which enables it to cooperate with a column wheel 44 controlled by the user via a push button (not shown). Depending on the angular position of the column wheel 44, the clutch rocker arm 36 can occupy an engaged or disengaged position.

[0017] In its disengaged position, the clutch rocker 36 keeps the shaft 26 of the seconds wheel 18 substantially perpendicular to the plate 32 and parallel to the axis B, which keeps the clutch wheel 38 out of contact with the chronograph wheel 24. The finishing gear 4 rotates continuously, driving the current time display 10 but without driving the chronograph wheel 24, which remains stationary under the action of a brake or a hammer controlled by the column wheel 44.

[0018] When it moves from its disengaged position to its engaged position following pressure exerted by the user on the pusher, the clutch rocker 36 tilts the shaft 26 of the seconds wheel 18 towards the chronograph wheel 24, as shown in an exaggerated manner by the angle α on the figure 3This engages the teeth of the clutch wheel 38 with those of the chronograph wheel 24. In the engaged position, the brake or hammer no longer acts on the chronograph wheel 24, allowing the finishing gear 4 to rotate it. The chronograph thus runs until the user stops it by pressing the pusher again to return the clutch lever 36 to its disengaged position.

[0019] Regardless of the position of the clutch rocker 36, the second gear 30 continues to mesh with the intermediate gear 16. The teeth of the second gear 30 and the intermediate gear 16 are indeed dimensioned to prevent any jamming when the clutch rocker 36 is in the engaged position.

[0020] The present invention enables the off-center seconds hand 20, carried by the seconds wheel 18, and the chronograph hand 22 to rotate in the correct direction, namely clockwise, when either hand is viewed through its respective crystal. This result is achieved without the addition of any linkage outside the finishing gear train 4, that is, outside the kinematic chain between the power source 2 and the escapement 6, a linkage which would be likely to generate backlash.

[0021] Like any finishing gear, the finishing gear 4 is constantly under tension due to the torque exerted on it by the power source 2 and its interaction with the escapement 6. The torque it transmits to the chronograph wheel 24 is therefore free of backlash. Consequently, the display accuracy is improved even compared to traditional chronographs that display current and elapsed time on a single face.

[0022] The present invention is also of particular interest in the case of an indirect seconds hand, where the current-time seconds hand is centered but driven indirectly by the off-center seconds wheel 18. In this case, the invention avoids the need for an additional linkage outside the finishing gear train, in the kinematic chain connecting the seconds wheel to the seconds hand or between the finishing gear train and the chronograph wheel.

[0023] The present invention is not limited to a watch movement comprising a chronograph mechanism. It can be applied to any watch movement comprising a chronograph, animation or other mechanism, controlled by means of a clutch, for the purpose of rotating the mechanism in the opposite direction to the seconds wheel of the finishing gear train, or more generally to the wheel of the finishing gear train that controls said mechanism, without increasing gear backlash.

Claims

1. Timepiece movement comprising a power source (2), a finishing going train (4), an escapement (6) connected to the power source (2) by the finishing going train (4), a resonator (8) cooperating with the escapement (6), a driven mobile (24), a coupling lever (36) and a coupling wheel (38) controlled by the coupling lever (36) in order, with the coupling lever (36) in a coupled position, to mesh with the driven mobile (24) in order to transmit the rotation of the finishing going train (4) to the driven mobile (24) and, with the coupling lever (36) in a decoupled position, to be out of contact with the driven mobile (24), characterised in that the coupling wheel (38) forms part of a mobile (18) of the finishing going train (4).

2. Timepiece movement as claimed in claim 1, characterised in that the shaft (26) of said mobile (18) of the finishing going train (4) is guided in rotation on one side in a fixed part (34) of the timepiece movement and on the other side in the coupling lever (36).

3. Timepiece movement as claimed in claim 1 or 2, characterised in that said mobile (18) of the finishing going train (4) is a seconds mobile.

4. Timepiece movement as claimed in claim 3, characterised in that the seconds mobile (18) is eccentric with respect to the timepiece movement.

5. Timepiece movement as claimed in any one of claims 1 to 4, characterised in that the driven mobile (24) is a chronograph mobile.

6. Timepiece comprising a timepiece movement as claimed in any one of claims 1 to 5.

7. Timepiece comprising a timepiece movement as claimed in claims 4 and 5, characterised in that it comprises, on a first face, a seconds display of the current time (10, 20) driven by the seconds mobile (18) and, on a second face opposite to the first face, a chronograph display (14, 22) driven by the chronograph mobile (24).