US2728187A

US2728187A - Watch with indirectly driven minute hand

Info

Publication number: US2728187A
Application number: US304510A
Authority: US
Inventors: Stamm Heinrich
Original assignee: D Ebauches Eta S A Fab
Current assignee: D Ebauches Eta S A Fab; Fabrique D'ebauches Eta S A
Priority date: 1951-08-23
Filing date: 1952-08-15
Publication date: 1955-12-27
Anticipated expiration: 1972-12-27

Description

Dec. 27, 1955 STAMM WATCH WITH INDIRECTLY DRIVEN MINUTE HAND 2 Sheets-Sheet 1 Filed Aug. 15, 1952 Dec. 27, 1955 2 Sheets-Sheet 2 Filed Aug. 15, 1952 &

United States Patent WATCH WITH INDIRECTLY DRIVEN MINUTE HAND Heinrich Stamm, Grenchen, Switzerland, assignor to Fabrique dEbauches Eta S. A., Grenehen, Switzerland, a joint-stock company of Switzerland Application August 15, 1952, Serial No. 394,510 Claims priority, application Switzerland August 23, 1951 3 Claims. (Cl. 58-59) This invention relates to watches and more particularly to that kind of watches in which the minute hand is driven indirectly, being carried by a shaft or axle which is not comprised in the train of gear wheels which transmits the power of the main-spring from the barrel to the escapement.

In watches of the prior art, this so-called indirect drive presents the drawback that the play of the cannonpinion carrying the minute hand, in the teeth of the wheel which drives it, can cause displacements of the minute hand of more than a minute.

it has been tried to avoid this free play of the cannonpinion by providing a friction spring or washer between the cannon-pinion and a fixed part of the frame, but there always remains a certain lost motion between the cannon-pinion and the means which drives it. This lost motion renders a correct regulation of the watch impossible.

It is an object of this invention to provide a watch with an indirectly driven minute hand, in which the amount of shake of the minute hand is reduced in such a way that it is not noticeable any more, this reduction of the free play of the minute hand being obtained by providing a wheel on the cannon-pinion, said wheel being in meshing relation with a pinion of the train of gear wheels of the watch.

Such a wheel on the cannon-pinion has of course a much greater diameter than the normal circle of teeth of the cannon-pinion, and the amount of shake of the minute hand is consequently reduced, since the lost motion between two gears is constant and the corresponding angle of rotation of a gear is the smaller the greater the diameter of said gear.

This improvement regarding an indirectly driven mintue hand renders it possible either to make a new kind of watch which is not as thick as known watches, which both sweep second and minute hands driven directly, or to provide a watch with a greater barrel than that of these known watches.

It is known that with barrels of the same height, a watch with a sweep second is higher as a whole than a watch in which the fourth wheel is located eccentrically.

It has been tried repeatedly to avoid or at least diminish this undesirable height of watches with sweep second. However, all the improvements hitherto devised complicate the clockwork in such manner as to render it practically impossible to use them as small size watches such as ladies watches.

When driving the minute hand indirectly according to the invention, the great wheel must no longer be journalled in the center of the movement and the intermediate bridge for journalling this great wheel in the center of the movement can thus also be dispensed with.

Since the thickness of such a movement is conditioned on the different elements, which have to be provided, one above the other. in the middle of the watch in the case of a watch with seconds and minute hands directly driven,

the following elements have to be provided in the middle of the watch: the hour wheel, the cannon-pinion, the base plate, the barrel, the great wheel, the intermediate bridge carrying the upper bearing of the great Wheel, the fourth wheel with its pinion and the upper bridge carrying the upper bearing of that fourth wheel.

The improvement according to this invention allows removing the great wheel from the center and dispensing altogether with the intermediate bridge, while' providing a supplementary wheel on the cannon-pinion. The place saved by this improvement can then be utilized for the barrel which can be made thicker than in known watches with sweep second and directly driven minute hand. Moreover, since there is no great wheel pinion in the center which meshes with the barrel, the latter can also be made larger than with known watches.

In the drawings afiixed to this specification and forming part thereof three embodiments of this invention are illustrated diagrammatically by way of example.

In the drawings:

Fig. l is a developed cross-section of the first embodiment along the lines B-C-DEF in Fig. 2.

Fig. 2 is a plan view of the embodiment shown in Fig. 1 as viewed from above.

Fig. 3 is a cross-section, similar to that shown in Fig. l, of a second embodiment and Fig. 4 is an analogous section of the third embodiment.

Referring to the drawings and first to Figs. 1 and 2, the centre pinion 3 eccentrically located between the base plate 1 and the bridge 2 is driven by the toothed rim of the barrel 4. The centre" wheel 5 is in mesh with the pinion 6 of the third wheel 7 and this wheel 7 is in mesh with the fourth wheel pinion 8 located centrally in the clockwork. The fourth wheel 9 is in mesh with the pinion (not shown) of the escape wheel. The end, projecting above the dial, of the fourth wheel spindle is surrounded by a pipe 10 and is guided by it. This pipe 10 is forced by pressure into the base plate 1, but it might also be screwed into or consist of the same piece as the base plate or might be fixed in some other manner. The pipe 10 projecting from the side of the base plate turned towards the dial carries the cannon-pinion 11 and on this cannon-pinion is located, as usoal, for free rotation the hour wheel 12. Similarly the teeth 15 of the cannon-pinion are in mesh with the minute wheel 13. The indirectly driven centre wheel 14 is mounted by friction on the cannon-pinion and meshes with the pinion 6. The number of teeth of this train of wheels is so chosen that the cannonpinion turns through 360 per hour. The wheel 14 and the cannon-pinion 11 are coupled in such manner that during the normal operation of the watch the cannon-pinion and the motion work are carried along correctly. In order to be able to correct the position of the hands the cannon-pinion can be turned with a certain friction while the indirectly driven centre wheel is at rest.

The arrangement of the difierent parts of the clockwork shown in Fig. 1, as regards the level on which they are located, can be modified in certain ways.

Thus, for instance, the indirectly driven centre wheel 14 might be located at a level between the minute wheel 13 and the hour wheel 12 as shown by way of example in Fig. 3. However, it is also possible to arrange the indirectly driven centre wheel 14 above the hour wheel, viewed from the dial.

Fig. 4 shows the hour wheel 12 as being mounted on the pipe 10 for free rotation. The cannon-pinion 11 with the indirectly driven centre wheel 14 fixed on it by pressure is mounted on the hour wheel for free rotation. In consequence thereof the minute wheel pinion is located below the minute wheel 13 and the indirectly driven centre wheel is driven by a pinion 16' embracing with sufficient friction the spindle of the wheel 7.

A similar pinion seated with sufiicient friction on the spindle of the wheel 7 might of course be provided also in the first and second embodiments.

I Wish it to be understood that I do not desire to be limited to the details disclosed in the foregoing specification and illustrated in the drawings for obvious modifications will occur to a person skilled in the art.

I claim:

1. In a watch the combination of a base plate and a pipe in the center of this plate, a barrel, a train of gear wheels driven by said barrel and comprising a fourth wheel on a fourth Wheel spindle extending through said pipe and carrying 21 seconds hand, and a motion work comprising a cannon-pinion formed with teeth and rotatably arranged around said pipe, said cannon-pinion carrying the minute hand of the watch,. an hour wheel freely rotatable around said cannon-pinion and carrying the hour hand of the watch, a minute wheel in meshing relation with said cannonpinion, a minute wheel pinion fixed to said minute 4. wheel and in meshing relation with said hour wheel, and a wheel on said cannon-pinion in meshing relation with a pinion of the train of gear wheels for driving said motion work.

2. The Watch of claim 1, in which the hour wheel is free to rotate around the cannon-pinion, the wheel on the cannon-pinion being arranged between said minute wheel and said hour Wheel and the pinion of the train of gear wheels being the pinion of the thirdwheel.

3. The watch of claim 1, in which the cannon-pinion is free to rotate around the hour wheel, the wheel on the cannon-pinion being arranged above said hour Wheel and the pinion of the train of gear'wheels being mounted on a bracket portion of the third wheel spindle.

neferences Qited in the file of this'patent UNITED STATES PATENTS 2,029,559 Colomb Feb. 4, 1936 2,618,118 Harris Nov. 18, 1.952

FOREIGN PATENTS 528,558 France Aug. 20, 1921 206,229 Switzerland May 1, 1940 214,434 Switzerland July 16, 1941