EP1666990A2 - Anti-tripping device for timepiece escapement - Google Patents

Abstract

The anti-gallop device is intended for a detent escapement mounted on a wristwatch. It comprises a finger (5) fixed on the arm (3) of the rocker (2), two columns (6, 7) between which can pass the finger, these columns being integral with the bridge (4) of the balance, and an arm of locking (8) fixed on the outer turn (10) of the hairspring (1), this locking arm being capable of being interposed between said columns (6, 7) and said finger (5) to prevent the rotation of the balance wheel beyond an angle exceeding its normal operating angle. The locking arm is a clamp (8) hooked on the outer turn (10) of the spiral (1).

Description

The present invention relates to an anti-gallop device for a clock escapement, this escapement comprising, inter alia, a spiral composed of several turns and a rocker provided with at least one arm, the rocker being pivotally mounted between a plate and a bridge, said device comprising a finger fixed on the balance arm, at least one column next to which can pass the finger when the balance is moving, this column being secured to the bridge of said balance, and a locking arm fixed on the outer coil of the spiral, this locking arm being capable of being interposed between said column and said finger to prevent rotation of the balance beyond an angle exceeding its normal operating angle.

Such a device is known. It has been described in the book "Der Chronometer Gang" by Professor Alois Irk and published by Deutsche Uhrmacher Zeitung, Berlin, 1923. Particular reference is made to paragraphs 116 to 120 (pages 74 to 77) and figure 25 of the work cited.

This device is implemented in so-called expansion escapements that are suitable for large timepieces such as marine chronometers. These parts are appreciated for their great precision, which is why it is very often used a relaxation exhaust itself renowned for its high accuracy. This exhaust, however, has an important defect, namely its sensitivity to shocks. Because of this, it is considered not to be well suited to wristwatches. Indeed a shock applied to the timepiece can cause the pendulum to rotate beyond a normal operating angle. It then occurs a gallop because two clearances and two pulses occur during the same alternation.

When it is desired to equip a small timepiece, for example a wristwatch, with a detent escapement to replace for example the classic anchor escapement and thus benefit from the advantages conferred by this escapement, it will be using new techniques different from those known until today if we do not want to lead to failure. Various solutions have been proposed recently to overcome the lack of energy developed by the sprung balance of a wristwatch to overcome the forces acting on the trigger of a detent escapement. Nevertheless, the problem of galloping remains and it is to solve it when dealing with a small spiral, such as the one mounted on a wristwatch.

If one refers to the work cited above, one realizes that the proposed locking arm for the anti-gallop device is suitable only for a large spiral. It is actually a piece that has undergone several machining including a hole through which will pass the last turn of the spiral. Such a way of doing is not well suited to a small spiral, moreover its execution is heavy and complicated.

To overcome the disadvantages mentioned, the present invention, besides it obeys the generic definition in the first paragraph of this description, is remarkable in that the locking arm is a clamp attached to the outer coil of the spiral.

• la figure 1 est une vue en perspective du dispositif anti-galop montrant le bras de blocage selon l'invention,
• la figure 2 est une vue de profil montrant en conjonction les divers éléments entrant en jeu pour empêcher le galop de l'échappement, et
• la figure 3 est une vue en plan de la pince utilisée comme bras de blocage selon l'invention.

The features and advantages of the present invention will emerge from the description which follows, made with reference to the accompanying drawings, and giving as an explanatory example, but in no way limiting, an advantageous form of producing an anti-gallop device for a wristwatch with a detent escapement, drawings in which:

• FIG. 1 is a perspective view of the anti-gallop device showing the locking arm according to the invention,
• Figure 2 is a side view showing in conjunction the various elements involved to prevent the gallop of the exhaust, and
• Figure 3 is a plan view of the clamp used as locking arm according to the invention.

The anti-gallop device will now be described with reference to FIGS. 1 and 2. This device is intended for a watch exhaust, more particularly for a trigger escapement of which FIGS. 1 and 2 show only the elements necessary for the understanding of the invention namely a spiral 1 composed of several turns 9 and 10 and a rocker 2 provided with at least one arm 3 and pivotally mounted between a plate (not shown) and a bridge 4.

The detent escapement further comprises the following elements not shown in the drawings, namely: an escape wheel provided with generally pointed teeth which rest in turn on a pallet of rest, a rocker blocker recalled by a spring, this blocker carrying at its first end said pallet rest and at its second end a first actuating finger capable of being actuated by a second actuating finger carried by a plate integral with the balance, this plate also carrying a pallet of pulses adapted to receive pulses from the teeth of the escape wheel. At each oscillation of the balance wheel, the rest pallet is disengaged from the tooth of the escape wheel and one and other teeth of the same wheel, acting on the impulse pallet gives a pulse to the pendulum. It will be observed that the second actuating finger is arranged so as to actuate the first finger of the blocker only in a direction of rotation of the balance, that is to say during the first alternation of the oscillation then what takes place the impulse. When the rocker rotates in the other direction, that is to say during the second alternation of the oscillation, the first finger of the blocker is not actuated because the second finger carried by the plate is arranged for s' then hide from what no impulse occurs. The explanations that have just been given make it clear that if the first alternation causes the balance to rotate beyond a normal amplitude which is of the order of 320 degrees, for example following a shock applied to the shows, the first finger of the blocker can be operated a second time. There is then a second pulse during the same alternation, which causes the escapement to gallop.

To avoid this phenomenon, the anti-gallop device proposed in the work cited above and illustrated in Figures 1 and 2 of the present invention comprises a finger 5 fixed on the arm of the balance 2 and two columns 6 and 7 between which can pass the finger when the pendulum is moving, these columns being secured to the bridge 4 of the pendulum. The device also comprises a locking arm 8 fixed on the outer turn 10 of the hairspring 1. As shown particularly in FIG. 2, this locking arm 8 comes to interpose between the columns 6 and 7 and the finger 5 to prevent the rotation of the balance 2 beyond an angle exceeding its normal angle of rotation. Indeed, at the end of the first alternation, situation shown in Figure 1, the hairspring 1 and its last turn 10 have their largest expansions which leads the locking arm 8 fixed on the latter turn, to come between the finger 5 of the arm 3 and the two columns 6 and 7 of the bridge 4. At this moment, if a shock is applied to the timepiece and if this shock causes the balance to continue its rotation in the counterclockwise direction ( arrow A), the finger 5 abuts against the locking arm 8, the latter coming in turn against the columns 6 and 7 (situation illustrated in Figure 2). The pendulum 2 is then stopped preventing the second pulse discussed above. The gallop is thus avoided. Note that from this moment the pendulum will turn in the opposite direction to cover its second alternation. The hairspring 1 will tighten and the last turn 10 attracting the locking arm 8 towards the center. The locking arm 8 will therefore no longer be an obstacle to the passage of the finger 5 between the columns 6 and 7 that it will cross twice by oscillation.

As shown in FIGS. 1 to 3, the present invention is remarkable in that the locking arm 8 is a clamp attached to the outer turn 10 of the hairspring 1. This method is perfectly adapted to small spirals that we meet in wristwatches for example. The system envisaged does not require any complicated preparation and machining of the locking arm as is the case of the arm in the cited work. The clamp can be placed on the outer turn without difficulty, at the desired location, without the need to put on the spiral and fix it on the latter as provided in the same book.

The clamp 8 can be in various forms including that which is illustrated in Figures 2 and 3. Here the clamp has the shape of an X whose upper branches 11 and 12 are shaped to hug the spiral. Figure 3 shows particularly that the upper branches are cut in the form of beveled jaws to tighten well on the spiral. The lower branches 13 and 14 are arranged to serve as means for gripping and placing the clamp. A tool specially designed for this gripping and positioning will allow gripping the gripper by its branches 13 and 14 and then bringing them together to elastically separate the upper branches 11 and 12 to install them on the hairspring. It will be understood that this clamp 8 can be made from a blade by simple stamping or chemical etching.

Note finally that the two columns 6 and 7 integral with the bridge 4 could consist of two pins driven in this bridge. The present invention however provides for simplifying this passage by proposing, as shown in Figures 1 and 2, a gantry 15 whose two columns 6 and 7 are connected by a cross member 16, this cross member carrying a rod 17 driven into the bridge 4 of the pendulum 2.

It will also be noted that the device of the invention can be envisaged with a single column secured to the bridge 4.

Claims (5)

Anti-gallop device for a clock escapement, this escapement comprising inter alia a spiral (1) composed of several turns (9, 10) and a pendulum (2) provided with at least one arm (3), the balance being pivotally mounted between a plate and a bridge (4), said device comprising a finger (5) fixed on the arm (3) of the balance, at least a first column next to which can pass the finger (5) when the pendulum is in motion, this column being integral with the bridge (4) of said balance, and a locking arm (8) fixed on the outer turn (10) of the spiral (1), the locking arm being capable of interposing between said column and said finger (5) for preventing rotation of the balance beyond an angle exceeding its normal operating angle, characterized in that the locking arm (8) is a clip attached to the outer turn (10) spiral (1). Anti-gallop device according to claim 1, characterized in that it further comprises a second column and in that the finger (5) can pass between the first and second columns when the pendulum is in motion. Anti-gallop device according to claim 1 or 2, characterized in that the clamp (8) has the shape of an X whose end of the upper branches (11, 12) are shaped to elastically embrace the spiral and whose branches lower parts (13, 14) are arranged to serve as means for gripping and placing said clamp (8). Anti-gallop device according to claim 3, characterized in that the clamp (8) is a blade whose edges are obtained by chemical etching. Anti-gallop device according to claim 2, characterized in that the two columns (6, 7) integral with the bridge (4) balance form a gantry (15) with a cross member (16) connecting them, this cross carrying a rod (17) chased into the bridge (4) of the balance.

Images