Chronograph movement

Abstract

A conventional timepiece movement with a seconds hand, minutes hand and hour hand combined with a chronograph movement including a minutes counter and hours counter and having the capability to zeroize the seconds hand, minutes counter and hours counter.

Description

This invention relates to a chronograph movement comprising an hour-wheel and a minute-wheel continuously driven by a gear-train, and further comprising a chronograph-pinion and a minute-counter, each adapted to be stopped, returned to zero, or connected to the gear-train and driven.

Most of the known chronograph movements comprise the usual wheels and pinions of a watch movement and, in addition, a chronograph-arbor integral with a chronograph-wheel and means for connecting the chronograph-wheel to a fourth wheel-and-pinion, these means being controllable from the outside so as to cause the chronograph-hand to start and stop. When the chronograph is equipped with a minute-counter, the latter is driven from the chronograph-wheel, either by a finger actuating the counter-wheel by one step per revolution, or by an oscillating pinion which produces a continuous slow motion of the counter-hand.

In some of the known chronographs, the minute-counter is coaxial with the chronograph-hand. It is then connected to the center wheel-and-pinion by a friction coupling, and the mechanism comprises a brake which can block the counter when the chronograph hand is uncoupled.

All of these known mechanisms necessitate one or more levers bearing wheels intended to produce the drives needed to operate the chronograph-hand and the counter or counters. In certain cases, the chronograph-hand is driven via a friction clutch.

It is the object of this invention to provide a chronograph movement comprising a chronograph-pinion and a minute-counter, but not requiring either a lever or a brake, and being of simplified construction.

To this end, in the chronograph movement according to the present invention of the aforementioned type, the chronograph-pinion and the minute-counter each have toothings continuously engaged with corresponding toothings of a wheel-and-pinion constituting the driven part of a friction clutch, and the driving part of the clutch is a wheel-and-pinion of the gear-train.

A preferred embodiment of the invention will now be described in detail with reference to the accompanying drawing, which is a partial axial section through the chronograph movement.

Only those elements necessary for understanding the particularities of the chronograph movement described are illustrated. The elements which are not shown are of conventional design.

The drawing shows part of a base plate 1 of the movement and part of a wheel-train bridge 2. A chronograph bridge 3 is fastened under the base plate 1 in such a way that certain elements may pivot, as will be seen further on. Below the chronograph bridge 3 is a retaining plate 4, through a central opening 5 of which pass the various pipes of the members bearing the center hands. The retaining plate 4 also has an off-center opening 6 through which an arbor 7 of an hour-counter passes.

The chronograph movement illustrated comprises a mainspring lodged in a barrel which rotates at a slightly greater speed than usual. The drum of this barrel drives an off-center center wheel-and-pinion 8, part of the wheel of which may be seen in the drawing. The center wheel-and-pinion 8 likewise rotates at a slightly greater speed than usual, which is one revolution per hour, and pivots between the wheel-train bridge 3 and the base plate 1 about an off-center arbor. The wheel of the wheel-and-pinion 8 engages a pinion-toothing 9 of a third wheel-and-pinion 10, which is of a special design. The pinion-toothing 9 is integral with a toothed disc 11 which represents the wheel-toothing of the third wheel-and-pinion 10, and it is also integral with an auxiliary pinion-toothing 12 smaller in diameter than the pinion-toothing 9. As in a conventional movement, the wheel 11 drives an off-center fourth wheel pinion (not shown) which transmits the driving torque to an escape wheel actuating the escapement. The wheel-and-pinion 10 has a cylindrical passage along its axis, and it is mounted loose on an arbor 13 which pivots at its upper end in a bearing 14, integral with the bridge 2, and at its lower end in the bottom 15 of a socket 16 driven into an opening in the chronograph bridge 3. The sidewall of the socket 16 has a recess in order to enable the driving of the minute-counter, as will be seen further on.

The third wheel-and-pinion 10 is held in place axially by a shoulder of the arbor 13 on which the end face of the pinion-toothing 12 rests, and by a sleeve 17 driven onto the upper end of the arbor 13. The position of the sleeve 17 determines the clearance of the wheel-and-pinion 10.

Guided freely about the sleeve 17 is a clutch plate 18 provided with a peripheral toothing 19. The plate 18 is normally pressed against the wheel 11 by a resilient element 20 held under tension between a collar of the sleeve 17 and a circular rim of the plate 18. It can, however, be axially displaced with respect to the arbor 13 by means of a control member (not shown).

The plate 18 is adapted to drive the arbor 13 rotatingly by the friction of the resilient member or spring 20 on the rim of the plate 18 and on the sleeve 17, and hence a pinion-toothing 21, situated at the lower end of the arbor 13 inside the socket 16, is rotated with the wheel-and-pinion 10 or, on the contrary, blocked, according to the position of the control member of the plate 18. Thus the whole assembly constitutes a clutch, the driven part of which, consisting of the arbor 13 and the plate 18, comprises a number of toothings of different diameters which are coupled or uncoupled simultaneously.

The indicators of the chronograph movement described here are so arranged that they can be started, stopped, and returned to zero accurately and simply. The indicator members comprise, first of all, a chronograph-arbor 22, the upper end of which pivots in a bearing 23 integral with the bridge 2, while the lower end bears a chronograph-hand 24. The arbor 22 is machined with a pinion-toothing 25 which is constantly engaged with the toothing 19 of the plate 18. It carries a return-to-zero heartpiece 26 disposed immediately above the inner face of the base plate 1 and intended to cooperate with a hammer 26a. Near the lower end of the arbor 22 is a collar 27 which guides it in the inner bore of the pipe of a cannon-pinion 28. The arbor 22 has a frustoconical shoulder 47 between the toothed portion 25 and the portion of the arbor immediately adjacent thereto. On this shoulder 47 there rests a spring 48 consisting of a straight wire borne by a pillar (not shown) set upright in the base plate 1. The position and height of this pillar are such that the spring-wire 48 exerts an oblique force, acting in the direction indicated by an arrow F, upon the arbor 22. The spring 48 has a number of functions. First of all, it is a source of friction on the arbor 22. Furthermore, it prevents any jumping or wavering of the chronograph-hand at the moment of its starting up, i.e., when the plate 18 moves axially to come into contact with the plate 11. For this purpose, the hole of the bearing 23 is given a non-circular shape, slightly elongated in the direction determined by the parallel axes of the wheel-and-pinion 10 and the arbor 22. The spring 48 exerts upon the arbor 22 a force of which the horizontal component likewise acts in that direction and which consequently tends to press the pinion-toothing 25 against the toothing 19 of the plate 18. The profiles of these toothings will be such that the points of the teeth of the toothing 19 press against the bottoms of the tooth-gaps of the toothing 25 without the upper pivot of the arbor 22 pressing against the flank of the hole of the bearing 23. The length of this hole will be such that the short-side nearest the toothing 19 is never in contact with the upper pivot of the chronograph-arbor 22, while the opposite short-side offers sufficient play to absorb any eccentricity of the toothings 25 and 19, but little enough play to furnish support for the pivot of the chronograph-pinion 25 and thus to prevent disengagement of the toothings when the chronograph-pinion 25 is returned to zero.

This function of the spring 48 therefore ensures that the chronograph-hand will start up without any jerk, besides avoiding any risk of jamming due to possible eccentricity of the toothing 19.

Moreover, the vertical component of the force F acting in the direction of the axis of the arbor 22 presses the shoulder at the base of the upper pivot of the arbor 22 against the bearing 23, and this ensures the axial position of the arbor 22. It will be noted that this position is such that there is no risk of the heart-piece 26 coming into contact with the inner face of the base plate 1 and thereby being braked.

The details of this arrangement for avoiding angular play of the toothings may be described as follows: in a positioning arrangement for a rotating part having a toothing engaged with a driving toothing, the rotating part pivots with play in at least one bearing and comprises a shoulder against which a resilient element presses continuously, exerting upon the rotating part a force having an axial component and a horizontal component, the horizontal component being directed towards the axis of the driving toothing.

The cannon-pinion 28 has a toothing 29 extending between the base plate 1 and the chronograph bridge 3, the pipe of the cannon-pinion 28 passing through a circular opening in the bridge 3. The cannon-pinion 28 pivots in a hole in the base plate 1 and carries a friction-mounted minute-wheel 31 on a collar 30 having frustoconical flanks. The minute-wheel 31 is in continuous engagement with the pinion-toothing 12 of the third wheel-and-pinion 10. Thus the wheel 31 is driven at the rate of one revolution per hour and normally drives the cannon-pinion 28 at this same speed. The cannon-pinion 28 bears a minute-hand 32. It is guided at the level of the collar 27 in the end portion of a pipe 33 of the minute-counter which surrounds it, and it pivots in the opening in the chronograph bridge 3 provided for the passage of the cannon-pinion 28 and the chronograph-arbor 22. The pipe 33 is integral with a heart-piece 34 and bears a counter-wheel 35. The counter-wheel 35 is freely engaged on a cylindrical bearing surface of the pipe 33. The wheel 35 is of the same diameter as the wheel 31, and it meshes continuously with the toothing 21 of the arbor 13, this toothing 21 being of the same diameter as the toothing 12.

A spring 36 which rests on one face of a pinion 41 driven onto the pipe 33 positions the wheel 35 axially and produces the friction necessary to drive the heart-piece 34 and its pipe 33. A washer 37 which rests on the other face of the pinion 41 axially positions an hour-wheel 38 which extends immediately under the retaining plate 4, and the pipe of which passes through the opening 5 and guides the pipe 33. Thus under the minute-hand 32 there extends a minute-counter hand 39, fastened to the end of the pipe 33, and under this hand 39 there further extends an hour-hand 40, fastened to the end of the pipe of the wheel 38. The pinion 41 fastened rigidly on the pipe 33 is integral with the minute-counter and drives the wheel of a transmission wheel-and-pinion 42 mounted on a pivot pin 43 set upright in the base plate 1. The pinion-toothing of this wheel-and-pinion 42 drives a wheel 44 which is mounted on the arbor 7 in such a way as to be friction-coupled to the arbor 7. A heartpiece 45 is integral with the arbor 7, as is an hour-counter hand 46.

In order to establish the connection between the hour-wheel 38 and the toothing 29 of the cannon-pinion 28, and to enable the hand 40 to indicate the hour, a minute wheel-and-pinion (not shown) is provided between the base plate 1 and the retaining plate 4. This wheel-and-pinion will comprise a wheel-toothing engaged with the toothing 29 of the cannon-pinion 28 and a pinion-toothing engaged with the hour-wheel 38.

Thus the essential elements of the chronograph movement illustrated in the drawing have been described, and as may be seen, its operation derives from the arrangement described, particularly from that of the third wheel-and-pinion.

When the clutch is uncoupled by axial upward displacement of the plate 18, the pinion 25 and the wheel 35 are immediately blocked by the toothings 19 and 21. The wheel-and-pinion 10 continues to be driven by the center-wheel 8 and drives the wheel 31, the cannon-pinion 28, and, via the minute wheel-and-pinion, the hour-wheel 38, i.e., the hour and minute wheels and pinions of the movement. When pressure is exerted on the push-piece which returns the chronograph-hand and the counter-hands to zero, one or more hammers 26a, 34a and 45a act simultaneously upon the heart-pieces 26, 34 and 45 respectively. Due to the rotation of the arbor 22 driven by the heart-piece 26, the clutch-plate 18, which has remained engaged with the toothing 25 but is no longer in contact with the wheel-and-pinion 10, rotates against the friction of the spring 20. The heart-piece 34 causes the pipe 33 to rotate, returning the hand 39 to zero, but without necessarily driving the wheel 35, which is friction-fitted, and this facilitates the return to zero of the heart-piece 34. This rotating movement of the pipe 33 brings about a rotation of the pinion 41 and, consequently, of the wheel-and-pinion 42 and the wheel 44; but at the same time, the arbor 7, as well as the hand 46 and the heart-piece 45, rotates so as to return the hand 46 to zero. It follows that the arbor 7 rotates frictionally in the wheel 44.

To start up the chronograph, it suffices to move the hammer or hammers away from the heart-pieces 26, 34, and 45 and to release the plate 18, so that under the effect of the spring 20, it rests against the upper face of the wheel-and-pinion 10. From that moment on, the chronograph-hand is driven by the toothing 19, and the arbor 13 is driven via the spring 20, so that the toothing 21 drives the wheel 35 at the same speed as the wheel 31. The friction of the wheel 35 on the heart-piece 34, and that of the spring 36 on the pinion 41, cause the hand 39 of the minute-counter to turn, while the pinion 41 drives the wheel-and-pinion 42 and the wheel 44, which in turn drives the arbor 7.

Thus the arrangement described makes it possible to produce a chronograph with a continuous slow-motion minute-counter in the center. In this mechanism, when the chronograph members are stopped, the normal hour- and minute-hands turn freely under the action of the mainspring without being disturbed by the action of a brake acting upon one of the chronograph wheels or pinions. The setting of the hands 40 and 32 is made possible through the friction existing between the wheel 31 and the collar 30 of the cannon-pinion 28. The cannon-pinion 28 and the hour-wheel 38 may, as a matter of fact, be driven independently of the wheel 31 owing to that friction. In another embodiment, the minute-counter might also be off-center. The wheel 35 might remain engaged with the toothing 21 and drive the arbor of the counter by friction. Instead of serving to pivot the pipe 33, the hour-wheel 38 would then receive the pipe of the cannon-pinion 28 directly.

Claims

What is claimed is:

1. A chronograph movement comprising an hour-wheel and a minute-wheel continuously driven by a gear-train, and further comprising a chronograph-pinion and a minute-counter, each adapted to be stopped, returned to zero, or connected to said gear-train and driven, wherein said chronograph-pinion and said minute-counter each have toothings countinuously engaged with corresponding toothings of a wheel-and-pinion constituting the driven part of a friction clutch, and the driving part of said clutch is a wheel-and-pinion of said gear-train.

2. A chronograph movement in accordance with claim 1, wherein said minute-counter and said chronograph-pinion are coaxial with said hour-wheel and said minute-wheel.

3. A chronograph movement in accordance with claim 1, wherein said driving part and said driven part are coaxial.

4. A chronograph movement in accordance with claim 3, wherein said driving part comprises a pinion-toothing engaged with a center wheel-and-pinion and a wheel-toothing engaged with a fourth wheel pinion, said fourth wheel pinion and said center wheel-and-pinion constituting elements of other wheels and pinions of said gear-train.

5. A chronograph movement in accordance with claim 1, wherein said minute-wheel bears a cannon-pinion bearing a minute-hand, said minute-wheel being coupled to said cannon-pinion by a friction coupling.

6. A chronograph movement in accordance with claim 5, wherein said driving part further comprises a second pinion-toothing engaged with said minute wheel.

7. A chronograph movement in accordance with claim 5, wherein said two pinion-toothings of said driving part are of different diameters, and said center wheel-and-pinion is driven by a driving barrel at a speed greater than one revolution per hour.

8. A chronograph movement in accordance with claim 5, wherein said minute-counter comprises a counter-wheel engaged with a pinion-toothing of said driven part, a pipe engaged on said cannon-pinion, and a further pinion integral with a pipe of said minute-counter, said further pinion driving an hour-counter.

9. A chronograph movement in accordance with claim 8, further comprising a speed-reducing wheel-and-pinion, the wheel of which is engaged with said further pinion, and the pinion of which is engaged with a wheel of a wheel-and-pinion constituting said hour-counter.

10. A chronograph movement in accordance with claim 9, wherein said wheel of said hour-counter is friction-coupled to an arbor bearing an hour-counter hand.