US3643422A

US3643422A - Chronograph movement

Info

Publication number: US3643422A
Application number: US44512A
Authority: US
Inventors: Peter Bachmann
Original assignee: Ebauches Bettlach SA
Current assignee: Ebauches Bettlach SA
Priority date: 1969-06-10
Filing date: 1970-06-08
Publication date: 1972-02-22
Anticipated expiration: 1989-02-22
Also published as: FR2045949A1; CH514187A; CH882069A4; DE2028646A1; DE2028646B2; DE2028646C3; FR2045949B1

Abstract

This invention is exemplified by a hammer made in two pieces, a body piece and a lever piece. The hammer is used to return heart cams such as are used in stopwatches and counting devices to the zero position when a button is pressed. The hammer disclosed consists of a pivoted part which coacts with the button and a lever part which is held between the pivoted part and a platen in such a way that it drives the heart cams to zero position when the pivoted lever engages it at one point.

Description

Elite tates Patet achmann [54] CHRONOGRAPH MOVEMENT [72] inventor: Peter Bachmann, Bettlach, Switzerland [73] Assignee: Ebauches Bettlach S.A., Bettlach, Switzerland [22] Filed: June 8, 1970 211 Appl. No.: 44,512

[30] Foreign Application Priority Data June 10, 1969 Switzerland 8820/69 [52] ..58/74 [51] .G04f 7/04 [58] Field of Search ..58/76, 74

[56] References Cited UNITED STATES PATENTS 3,495,397 2/1970 Dubois ..5s/74 Feb.22,1972

FOREIGN PATENTS OR APPLICATIONS 1,519,224 2/1968 France ..58/74 Primary Examiner-Milton Kaufman Attorney-Stevens, Davis, Miller & Mosher [57] ABSTRACT This invention is exemplified by a hammer made in two pieces. a body piece and a lever piece. The hammer is used to return heart cams such as are used in stopwatches and counting devices to the zero position when a button is pressed. The hammer disclosed consists of a pivoted part which coacts with the button and a lever part which is held between the pivoted part and a platen in such a way that it drives the heart cams to zero position when the pivoted lever engages it at one point.

4 Claims, 2 Drawing Figures PATENTEBFEB22 1912 &

CHRONOGRAPII MOVEMENT The present invention has for its object a watch movement comprising a zero return hammer for cooperation with heart cams to assure the return to zero of the indicating members, this hammer being formed of at least two distinct parts connected to each other in such fashion as to permit a limited displacement of one of the parts relative to the other.

Theprincipal purpose of this invention is to provide a solution to a problem which is presented when one actuates the hammer of a watch movement to cause it to bring to zero simultaneously several indicating members, for example the second hand and the minute hand of a stopwatch as when one presses on the return to zero button after the stopping of the watch.

Generally, the zero return hammer is constituted of a cut and folded piece which pivots around a screw carried on the platen of the movement and which presents as many arms as there are heart cams to actuate. The hammer is generally moved into engaging position when one presses on the engaging push button and it is directly actuated by the return to zero button so as to pivot about its axis when one presses the pushbutton. The extremities of the arms of the hammer each come into contact with one of the heart cams and drive it in the starting position. The displacement of the pushbuttons and of the hammer are in general assisted by springs one of which, it could be, is cut out with the hammer but the parts which actuate the heart cams are rigidly connected to the principal part of the body of the hammer. As a consequence to assure the return to zero of all the indicating members, it is necessary that the contours of the elements be exactly adjusted so as to avoid that one or the other of these elements should present a slight play when the others are in the zero return position. In the movements of the counters and watches known up to the present, it is necessary to file, polish or adjust the hammers of each piece so as to have a correctly functioning return to zero for each of the heart cams that has to be actuated. It is therefore evident that by avoiding the necessity for an adjustment of each hammer one simplifies manufacture and particularly the operations of assembly and quality control.

There are already known watch movements in which the part which forms the hammer is formed of two pieces pivoting on one another, a spring being biased between these two pieces. Each one of the pieces comprises an arm the extremity of which cooperates with the heart cams. This arrangement naturally avoids the adjustment difficulties of the extreme margins of the two arms of the hammer. One of the two pieces constitutes the body of the hammer and pivots on the support for the movement. It is this part which is actuated by the return to zero pushbutton. Meanwhile at the time of operation of the return to zero, the heart cam is actuated by the piece connected to the body of the hammer by a spring and thus is influenced only by the force resulting from the loading of this spring. The return to zero conditions are not identical for the two heart cams. This solution is revealed as unacceptable in a movement of a chronograph and the invention envisages the establishment of a rigid connection between each heart cam and the push buttonthrough the intermediary of the different parts of the hammer at the moment of the return to zero.

In a watch movement according to the invention, this objective is attained by the fact. that one of said parts is pivotally mounted on the platen for movement and the other part is connected to the first one so as to hold the two heart cams in zero position when pressed at one point by the first one.

The annexed drawing shows, by way of example, an embodiment of watch movement according to the invention.

FIG. I is a fragmentary top plan view; and

FIG. 2 is a view in section taken on the line II-II of FIG. 1.

In the drawing the platen or support 1 of the watch movement is a circular disc approximately one-fourth of the surface of which is shown. In its center, this platen has an opening which permits passage therethrough of a second hand shaft on which there is mounted a sleeve 2 fixed to a heart cam 3. The position of this heart cam and of the sleeve 2 is conventional and will not be described further in detail. The sleeve 2 protrudes through a central opening of the watch face (not shown) and carries a second hand at its end which lies above the watch face. The actuating means which puts the second hand shaft in rotation are not shown and are arranged in the usual way.

The movement described includes also a minute totalizer the indicating means for which is mounted on the sleeve which pivots about a shaft advancing step by step once each minute. The magnitude of each step of angular displacement which the shaft accomplishes for each rotation of sleeve 2heart cam 3 unit is equal for example to one-thirtieth of a revolution or 12. The heart cam 5 is attached to the sleeve 4 and extends a little distance between the center and margin of the platen 1.

As the means of control, the described watch movement includes an engaging and disengaging lever (not shown). which presents two little tongues turned down to the plane of the platen and sticking out from the side of the movement so as to cooperate with two pushbuttons, one for the engagement of the second hand and the other for stopping it. The movement also includes a return to zero hammer 6 which is composed of a hammer body 7 and of a hammer lever 8. These two pieces are of cut sheet metal and are interconnected. The hammer body 7 has a little tongue 9 which is turned down at 90 and engages in a notch 10 in the periphery of the platen. This little tongue coacts with the return to zero pushbutton. A resilient arm 11 left from the cutting out of the body 7 plays the role of a return spring. The end of the arm 1 l is pressed against a stud l2 fixed in the platen. In addition, the body 7 of hammer 6 pivots on the screw bearing reference numeral 13 which is threaded into the platen. The body of the spring presents a little tongue 14 twice bent 90 and engages in the slot 51 of the platen. Thanks to these elements, the body 7 of hammer 6 can be mounted on the platen 1 so as to pivot about the axis of the screw 13. The projection 16, which is along the edge of the body 7, is designed to cooperate with the engagement and disengagement lever. When the hammer is in the position shown in the drawing, the engagement and disengagement lever rests on the projection 16. Thus when one presses the engagement push button, the pivoting of this lever displaces the body of the hammer 6 in the counterclockwise rotation as viewed in FIG. 1. In these conditions, the lever 8 of the hammer moves away from the

heart cams

3 and 5, and the movement being engaged, the second hand immediately begins to turn around its axis while the minute totalizer advances automatically one step for each rotation of the second hand.

In addition to the elements mentioned the body 7 of the hammer 6 presents an elongated cut out 18 limited at its two extremities by two

little tongues

19 and 20 located in the plane of the body of the hammer and each presenting a

reentrant flange

20a and 19a. In addition, the body of the hammer 6 is cut out with two

little tongues

21 and 22 which are bent to extend in a plane parallel to that of the body 7 of the hammer 6 but slightly offset from it in the direction opposite to the platen as one sees in FIG. 2. The

little tongues

21 and 22 are not themselves exactly parallel to the body 7 of hammer 6 but are disposed slightly obliquely in such a way that their ends rest on the lever 8 of hammer 6. The latter is made of a plain piece of cutout sheet metal of the same thickness as the body 7 of the hammer. It is maintained in place on the platen 1 by the

little tongues

21 and 22. Additionally it is retained in a longitu dinal sense by the

little tongues

19 and 20. Finally it is connected to the body of the hammer by the

reentrant flanges

19a and 20a which surround its two extremities The internal lengthwise boundary presents located between the extremities, the rounded peak of which is in contact with a part of the edge of the cutout 18. Finally the lever 8 of the hammer has two

striking elements

24 and 25 which control the

heart cams

3 and 5.

When one wants to pivot the hammer away from the position of disengagement in the clockwise sense as viewed in FIG. 1, pressing of the push button which acts on the little tongue 9 brings the two

elements

24 and 25 in contact with the

heart cams

3 and 5. If one of these elements enters in contact with a triangular projection 23 the heart cam which it controls before the other, it produces a slight pivotal movement of the lever 17 around point 23 which brings the other element very rapidly into contact with its heart cam. At the end of the movement of the hammer the two heart cams are found at zero, the two

elements

24 and 25 are each in contact with one of them, and the body of the hammer is found in a position such that the projection 23 rests against the back ofthe cutout 18.

While the present invention has been described in connection with a stopwatch, it can be utilized in all sorts of movements for actuating a counting type indicating means and a totalizer arranged in such a way that the two can be returned I to zero simultaneously whether the device be a watch or merely some other sort of counter.

What is claimed is:

l. A watch movement, comprising at least two heart cams for controlling the return to zero of interval indicating means; a support member; and a hammer comprising first and second parts, said first part being mounted for pivotal movement on said support member, said second part having surfaces for en gaging said heart cams, said first part having tongues for retaining said second part in substantially the same plane as said first part and for holding said second part against said support member, said second part having a generally triangular projection, the peak of said projection engaging an edge portion of said first part and constituting a pivotal point for said second part, the edge portion of said second part opposite said projection having two further projections engaging each of said heart cams, respectively, wherein upon pivotal movement of said first part said edge portion thereof engages said triangular projection to cause said further projections to engage said heart cams to move them to their respective zero positions.

2. A movement according to claim 1 in which the body part of the hammer has means to encage the extremities of the lever part to prevent it from moving in the longitudinal sense.

3. A movement according to claim 2 in which said encaging means includes reentrant hooks holding the hammer lever with the hammer body while at the same time permitting limited play between the two pieces.

4. A watch movement comprising a support member; at least two heart cams; and a hammer comprising first and second parts extending in substantially the same plane, said first part having a cutout portion comprising a striking edge portion and two reentrant edge portions, said first portion being pivotally mounted on said support member, said second part loosely engaging said cutout portion and having two striking elements engaging said heart cams, respectively, said second part further having a pointed portion which engages said striking edge portion, said striking elements comprising means to return said heart cams to zero upon pivotal movement of said first part, said second part still further having two return means spaced apart on both sides of said pointed portion, said return means cooperating with said reentrant edge portions to displace said second part away from said heat cams when said first part is moved from an engagement position with said second part into a position out of engagement therewith.

Claims

1. A watch movement, comprising at least two heart cams for controlling the return to zero of interval indicating means; a support member; and a hammer comprising first and second parts, said first part being mounted for pivotal movement on said support member, said second part having surfaces for engaging said heart cams, said first part having tongues for retaining said second part in substantially the same plane as said first part and for holding said second part against said support member, said second part having a generally triangular projection, the peak of said projection engaging an edge portion of said first part and constituting a pivotal point for said second part, the edge portion of said second part opposite said projection having two further projections engaging each of said heart cams, respectively, wherein upon pivotal movement of said first part said edge portion thereof engages said triangular projection to cause said further projections to engage said heart cams to move them to their respective zero positions.