CH715425B1 - Differential mechanism and timepiece comprising it. - Google Patents

Abstract

The present invention relates to a differential mechanism (1) for a timepiece, comprising at least one frame (3, 5), and a gear train comprising a plurality of mobiles (11,12,13, 14) arranged in kinematics with each other, said mobiles (11, 12, 13, 14) being arranged to form one input and two outputs or two inputs and one output of the differential mechanism (1) so as to transmit, respectively receive, a differential torque by coupling of said mobiles (11, 12, 13, 14) to an input mechanism or annex outputs. At least two said mobiles (11, 13, 14) are mounted free to rotate around a specific axis (X1, X2) via a ball bearing (15, 16, 17) relative to the frame. This differential mechanism can be used to average the rate of two tourbillons or to display the power reserve. The invention also relates to a timepiece comprising such a differential mechanism.

Description

Technical area

The present invention relates to the field of watchmaking. It relates, more particularly, to a high-efficiency differential mechanism for transmitting motor torque between one or more driving sources of a watch movement and one or more display members or complications of the movement, such as for example a rotating regulating system of whirlwind or carousel type.

State of the art

[0002] The use of differential mechanisms is well known in the mechanical industries and in the field of watchmaking in particular. In this field, such differentials are used in particular in mechanisms for indicating the power reserve of a watch engine to take at the level of two inputs of the differential the information of the running energy available at the level of the gear train. reassembly at the motor input and of the going train at the motor output, and via a differential output to transmit the difference between the two inputs to a suitable display device or mechanism.

[0003] Such a differential mechanism can also be used to average the rotations in a multiaxial rotating regulating system, as for example described in application EP 2786214 A1, or even to average the rate differences of two regulating systems of the balance-spring type. as in the „Duality“ timepiece designed by Philippe Dufour.

[0004] In the various known embodiments, the pivots of the differential mobiles are usually mounted on stones driven into the bridges and/or plate of the watch movement. This proves to be both expensive and mechanically very low yield due to the high friction at the pivot-stone contacts. Appropriate lubrication makes it possible to partially compensate for the energy losses resulting from this friction, but this is however far from being optimal.

Disclosure of Invention

[0005] The invention aims to provide a differential mechanism for a timepiece which provides significantly improved performance compared to known mechanisms of the state of the art.

To this end, the invention provides a differential mechanism as defined in claim 1.

[0007] Such a differential mechanism, the mobiles of which are mounted in rotation on ball bearings, has a significantly improved performance compared to the mechanisms of the prior art. In addition, although it is laid out flat, it does not require an intermediate mounting bridge for the transmission satellite between the input mobiles of the mechanism on the frame.

The invention also relates to a timepiece comprising such a differential mechanism.

Brief description of the drawings

Other details of the invention will appear more clearly on reading the description which follows, made with reference to the appended drawing representing a view in longitudinal section of a differential mechanism according to the invention according to a sectional plane containing the pivot axis of a watch movement second mobile.

Embodiment of the invention

The present invention provides a flat differential mechanism 1, a preferred embodiment of which is shown in the single appended figure. The differential mechanism 1 comprises gear mobiles 11, 12, 13, 14 arranged to form one input and two outputs or two inputs and one output depending on the configuration of implementation and use of the differential mechanism 1. The mobiles 11 , 12, 13, 14 each consist of a toothed wheel or pinion, on the periphery of which they are adapted to be coupled with a mobile motor or a mobile driven according to their function in use (input or output).

In the example shown, the differential mechanism 1 is used to average the rate of two tourbillon mechanisms (not shown) associated in parallel in a watch movement.

[0012] It thus comprises an input mobile 12 formed of a pinion driven on the second axis 2 of a watch movement and pivoting about a vertical axis X2. Two output mobiles 11, 13 are for their part mounted mobile in rotation also around said axis X2, each being fixed to a frame element 3, 5 of the differential mechanism 2, in this case formed of an upper bridge 3 and a lower bridge 5, advantageously integral with the frame of a timepiece receiving the differential mechanism 1. Finally, a satellite 14 is arranged to move in rotation around a vertical axis X1 and inserted between the two output mobiles 11, 13. The satellite 14 is movably mounted on the upper wheel set 11 and carries a pinion 18 meshing with the input pinion 12 and is coupled on its peripheral teeth to the lower wheel set 13 via an output pinion 19.

According to the invention, each of the output mobiles 11, 13 and the satellite 14 of the differential are mobile in rotation around their axes X2, X1 by means of a particular ball bearing 15, 16, 17 as opposed to prior devices using lubricated stones. The upper output wheel set 11 is thus mounted by its rotating hub on the internal cage of a first ball bearing 15, the external cage of which is inserted by force into an orifice provided for this purpose in the upper bridge 3 of the frame of the mechanism 1. Similarly, the lower output mobile 13 is mounted by its rotating hub on the inner cage of a second ball bearing 17, the outer cage of which is inserted by force into an orifice provided for this purpose in the lower bridge 5 of the mechanism frame 1.

Advantageously, the ball bearings 15, 16, 17 of the differential mechanism of the invention are ceramic bearings, in particular produced and marketed by the company MPS Micro Précision Systems SA, in Biel, Switzerland.

Finally, and in an original way in accordance with the invention, the satellite 14 is itself mounted by means of a third ball bearing 16 directly in the plate of the upper output mobile 11, said third bearing at balls 16 comprising an internal sleeve 161 of axis X1 inserted by force into the hub of the satellite 14 so as to secure said input wheel set to the third ball bearing 16. The satellite 14 of the differential mechanism 1 of the invention is thus suspended on the upper output mobile 11 and mobile with respect to the latter around its axis X1 under the drive of the driving force of the watch movement which is transmitted to it by the second axis 2 and the input pinion 12.

For this purpose, the input pinion 12 is driven on the second axis 2 and engages the satellite pinion 18 driven on the hub 141 of the satellite 14 coaxial with its axis of rotation X1. The second axis 2 and the input pinion 12 are fixed to each other in rotation around the longitudinal axis X2 of the second axis 2, which is free with respect to the output mobiles 11, 13 of the differential mechanism 1. As shown in the figure, the second axis 2 thus extends axially along X2 with play through an output pinion 19 driven into the hub 131 of the output wheel set 13 of a leaves and through the hub 111 in which it is secured in position and free to rotate by passing its end shank 22 through a pierced stone 4 driven into said hub 111. Of course, the stone 4 could also be also replaced by a bearing. The two output wheels 11, 13 are themselves capable of being coupled by their toothed crowns to the cage of a tourbillon in order to transmit to the latter the driving energy of the movement, in the manner of an average wheel in a movement conventional example, the respective cages of the two tourbillons each coupled to an output wheel set 11, 13.

The differential mechanism 1 of the invention thus makes it possible to transmit efficiently with high efficiency by a single input mobile 12 a motor torque to two consumer devices with reduced losses compared to existing watchmaking differentials as in the example given above or vice versa to average a motor torque from two motor sources to a single consumer device. In addition, it makes it possible to dispense with the intermediate satellite support bridge 14, the latter being suspended on an upper output mobile 11 and thus to simplify the structure and reduce the size of the flat differential mechanism.

[0018] This provides an alternative differential mechanism that is simple in structure and at reduced cost for clockwork mechanisms.

Claims (10)

1. Differential mechanism (1) for a timepiece, comprising at least one frame (3, 5), and a gear train comprising a plurality of mobiles (11, 12, 13, 14) arranged in kinematic connection with each other with the others, said mobiles (11, 12, 13, 14) being arranged to form one input and two outputs or two inputs and one output of the differential mechanism (1) so as to transmit, respectively receive, a differential torque by coupling of the said mobiles (11, 12, 13, 14) to an additional input or output mechanism, characterized in that at least two said mobiles (11, 13, 14) are mounted free in rotation around a specific axis (X1, X2) via a ball bearing (15, 16, 17) relative to the frame. 2. Mechanism according to claim 1, characterized in that one of said mobiles is a satellite (14) rotatably mounted directly on a second (11) of the mobiles of the gear train and kinematically coupled with the third mobile (13). 3. Mechanism according to claim 2, characterized in that the satellite (14) is inserted between the second (11) and third (13) mobiles. 4. Mechanism according to one of claims 2 or 3, characterized in that two of the mobiles (11, 13) are coaxial around an axis of rotation (X2) different from the axis of rotation (X1) of the satellite ( 14) and each rotatably mounted on a frame element (3, 5). 5. Mechanism according to one of claims 1 to 4, characterized in that the ball bearings (15, 16, 17) are bearings at least partially made of ceramic. 6. Mechanism according to one of claims 1 to 5, characterized in that the mobiles (11, 12, 13, 14) are toothed mobiles. 7. Timepiece comprising a differential mechanism according to one of claims 1 to 6. 8. Timepiece according to claim 7, comprising a watch movement provided with at least one driving source and at least two regulating systems arranged in kinematic connection with the driving source arranged in kinematic connection by a going train and an escapement, characterized in that a first input mobile (12) of the differential mechanism (1) is coupled to a mobile of the going train, two remaining mobiles (11, 13) being coupled at the output each with an escapement mobile or a respective mobile of the at least two regulating systems. 9. Timepiece according to claim 8, characterized in that the regulating systems are rotating regulating systems of the tourbillon or carousel type. 10. Timepiece according to claim 7 comprising a watch movement provided with at least one barrel comprising a mainspring and a power reserve mechanism, characterized in that a first mobile of the differential is coupled to a drive shaft winding the barrel spring, a second mobile is coupled to a toothing of the barrel, the last mobile of the differential being coupled to a display device of the power reserve mechanism.