US3142955A - Power clutch for the main spring of watch movements and the like - Google Patents

Description

1964 R3. A. FIECHTER 3,142,955

THE MAIN SPRING 0F. TS AND THE LIKE 3 Sheets-Sheet 1 POWER CLUTCH FOR WATCH MOVEMEN Filed Feb. 27-. 1961 3E INVENTOR Rm aim BY W M r ATTORNEYS 4, 1964 R. A. FIECHTER 3,142,955

POWER CLUTCH FOR THE MA SPRING 0F WATCH MOVEMENTS AND E LIKE Filed Feb. 27, 1961 5 Sheets-Sheet 2 m 3' n if?? ATTORNEYS R. A. FIECHTER 1964 POWER CLUTCH FOR THE MAIN SPRING 0F 3,142,955

WATCH MOVEMENTS AND THE LIKE Filed Feb- 27, 1961 5 Sheets-Sheet 5 INVENTOR I WW (1.

ATTORNEYS United States Patent 3,142,955 POWER CLUTCH FOR THE MAIN SPRING 0F WATCH MOVEMENTS AND THE LIKE Rene A. Fiechter, 137 Hollywood Ave., Douglaston 63, N.Y. Filed Feb. 27, 1961, Ser. No. 91,676 13 Claims. (Cl. 5883) This invention relates to a power clutch for the main spring of watch movements and other precision instruments.

It is an object of the invention to provide an arrangement whereby the main spring is prevented from be ng overwound and is released from the final winding tension in an improved manner.

It is a further object of this invention to eliminate the customary click and click spring arrangement and to replace it with a smoothly operating clutch system which allows the ratchet wheel to come back farther than in the customary arrangement.

It is another object of this invention to improve the quality of the watch by suppressing the noise of the customary click arrangement.

It is a further object to provide the above improvements by means which can be added easily to existing watch movements without the necessity for extensive rebuilding or rearrangement of other parts therein.

It is another object of this invention to add a functional roller bearing clutch, together with a fiat plate having a surface adapted to be engraved or decorated so as to. enhance the appearance of the watch movement.

It is a further object of this invention to provide means for obtaining the foregoing advantages without increas ing the thickness of the watch movement to any noticeable extent. I

In the operation of watches and other time keeping instruments consisting of a main spring, a train of wheels, an escapement and a balance wheel, the isochronism of the system can only be guaranteed when the variations of amplitude of the balance wheel are small. These var ations are directly affected by the force applied to the balance wheel by the escapement. That force derives from the main spring. It is therefore essential that the main spring should produce as consistent an output of energy as possible. As the curve obtained by plotting the torque released by the main spring in relation to the number of turns of the main spring in its barrel shows a very sharp increase when the main spring has reached its total capacity (that is, is fully wound), it has been the practice to release the main spring by means of a click pressed against a ratchet by a click spring in such a way as to release one or two teeth of the ratchet wheel after it is wound fully. This prevents the watch from being overwound. Because of the size of the construction, such clicks only release one, or sometimes two teeth, resulting in a release of an angle of ten degrees, approximately. This is not sufficient to remove the excess of torque, but just prevents the watch from being overwound. In order to remove that excess of torque completely, a backlash of thirty to forty degrees would be desirable. The present invention relates to improving the means of releasing the main spring without having to reconstruct the watch or time piece to do so.

A practical embodimentis shown on a greatly enlarged scale in the accompanying drawings in which:

FIG. 1 represents a detail plan view of the ratchet 3,14i2fi55 Patented Aug. 4., 1964 ice wheel, crown wheel, barrel, and center pinion portion of a watch movement, to which the new clutch mechanism has been added, parts being broken away;

FIG. 2 represents an axial section on the line II-II of FIG. 1, parts being broken away;

FIG. 3 is a graphic representation of a typical torque pattern of a watch spring;

FIG. 4 represents a detail axial section, corresponding to the upper portion of FIG. 2, showing an alternative form of clutch;

FIG. 5 represents a detail section taken on the line VV of FIG. 4;

FIGS. 6, 7 and 8 represent detail sections corresponding to the right hand end of FIG. 4, showing additional alternative clutch arrangements;

FIG. 9 represents an axial section, similar to FIG. 2, showing a modified interconnection of parts similar to those shown in FIGS. 1 and 2;

FIG. 10 represents an axial section, similar to FIGS. 2 and 9, showing another modified interconnection of the parts of the clutch assembly, parts being broken away;

FIG. 11 represents a detail top plan view of the parts shown in FIG. 10;

FIG. 12 represents an enlarged elevation, partly in section, of a separate hub unit for use in the assembly of FIGS. 10 and 11;

FIG. 13 represents a top plan view of the hub unit shown in FIG. 12; and

FIGS. 14, 15 and 16 represent axial sectional views of three alternative types of lubricant-holding composite rollers, suitable for use in the combinations of FIGS. 1, 2, 9, l0 and 11, the rollers shown being, respectively, a freely assembled two-part roller, a composite two-layer roller with lenticular inter-faces, and a three-layer composite roller with parallel inter-faces.

Referring to the drawings, the barrel 1 containing the main spring 2 is mounted on the barrel arbor 3 in the usual manner, the barrel teeth engaging the center pinion 4 to drive the center wheel 5. The barrel arbor is shown as being journaled in a barrel bridge 6, above which the arbor is squared, at 3', to engage tightly a square opening in the middle of the special ratchet '7. (The features just explained are common to each of the alternative forms described below and so will not be further referred to in detail.) The special ratchet 7 has an annular channel 8 in its upper face, the outer wall 9 of the channel being a cylindrical surface coaxial with the arbor 3 and being finely finished. The special ratchet is provided around its periphery with teeth 10 engaged by the teeth of the crown wheel 11 to transmit the watchwinding force from a stern (not shown) to the special ratchet 7 in the usual manner. The special ratchet is held firmly on the arbor by means of the wide headed screw 12. While the present invention eliminates the customary click and click spring, the word click is used in describing the click cam 13 and click plate 14 as an indication of their function. The click cam 13 fits freely in the channel 8 of the special ratchet 7 and is provided with an upwardly projecting annular collar 13 which is press-fitted into an opening in the click plate 14. The click plate is shaped to cover the whole of the channel 8 and is fixed in place by means of the click screw 15 (the screw on which the click or pawl is mounted in a normal watch movement), passing through a lateral extension from its otherwise generally circular body, as clearly shown in FIG. 1.

. to the positions indicated by full lines in FIG. 1.

' wardly inclined portion 26".

The click cam 13 is bounded peripherally by a series of cam surfaces 16 separated by stops in the form of teeth 17, the surfaces being generated by lines parallel to the axis of the barrel arbor, and each including a portion 16 which is coaxial with the wall 9 of the channel 8 and a portion 16" which lies at progressively decreasing radial distances from said wall. In the typical arrangement shown in FIG. 1 the teeth 17 lie at 40 intervals so that there are nine teeth and nine cam surfaces. Engagement between the special ratchet 7 and the click cam 13 is effected by means of rollers 18, of cylindrical form and having a diameter slightly less than the radial distance between the cam surface portion 16 and the wall 9,

I there being preferably one roller for each of the nine cam surfaces 16, and the rollers being preferably of jewel material.

In operationpit will be seen that rotation of the crown wheel 11 in the direction ofthe arrow W will rotate the special ratchet 7 in the direction of the arrow W", during which operation the clutch rollers will tend to move freely When the application of winding force to the crown wheel is discontinued, either during winding or when the spring 2 has reached its fully wound condition, the special ratchet 7 Will back off in the direction of the arrow BL and will move one or'more of the rollers 18 toward the cam surface portion 16" where the roller or rollers will become wedged between said portion and thewall 9, as indicated in broken lines in FIG. 1, the reverse motion of the ratchet thus being effectively arrested. The backlash permitted by this roller clutch can be determined largely by the number and dimensions of the cam surfaces 16 and can be made much greater than the or so permitted by an ordinary click construction, e.g., 30 to 40.

' Referring to the diagram of FIG. 3, the OX axis repre-' sents number of turns of the mainspring, the OY axis represents units of force of the spring, the area OABCD represents loss through friction and the line EF represents a desired uniform mean rate of increase (or decrease) of the actual torque force of the spring. As the spring reaches its fully wound condition, its force rises abruptly to the point B. If the winding is stopped there, with little or no backlash, and the watch starts to run, the output of force 7 drops rapidly from the too-high point B to the normal range beginning at C, causing erratic and inaccurate functioning of the timepiece. When sufficient backlash is per- 1 mitted, so as to eliminate all or most of the BC peak, it

willbe apparent that much more accurate operation can be achieved.

In the form shown in FIGS. 1 and 2 the roller clutching action is radial, between the cam surfaces 16 and the wall 9 of the channel 8. As an alternative it is possible to arrange forclutching action in an axial direction, as shown in FIGS. 4 to 8. According to FIG. 4 the barrel arbor 2t journaled in the barrel bridge 21, has a cam wheel 22 secured to its squared upper end by means of the screw 23. The cam wheel 22 has teeth 24 which are engaged by the teeth of a crown wheel (not shown) for winding, and the under surface of the cam wheel is pro vided with an annular cam groove of undulating or ser- I balls 28 (preferably of jewel material) are disposed, one in each cam section of the groove. diameter slightly less than the distance from the cam portion 26' to the base '27. During the winding operation The balls have a the wheel 22 moves in the direction of the arrow W in FIG. 5, with the balls rolling freely in the space between cam portion 26" and the base 27, as shown in full lines. When the winding force is discontinued the wheel 22 will back oil in the direction of the arrow BL* until one or more of the balls become wedged between the cam portion 26 and the base, as indicated in broken lines, the extent of such backlash being determined as before largely by the length and number of the cam sections 26.

As other alternatives, the balls 23 could be replaced by rollers 30, as shown in FIG. 6; or by a ball 31 and a roller 32 as shown in FIG. 7; or by a plurality of balls 33, as shown in FIG. 8. Either the single ball arrangement of FIGS. 4 and 5 or the single roller of FIG. 6, is generally to be preferred.

When it is desired to take apart the click assembly shown in FIGS. 1 and 2, as for cleaning or repair, the screws 12 and 15 are removed and the plate 14 with click cam 13 fitted therein can be lifted off, exposing the rollers 18 and ratchet 7 which can also be lifted oif together or separately as desired. Since the rollers are very small there is some danger that one or more of them may be spilled or dropped into the movement (after the plate 14 and cam 13 have been removed) causing delays, inconvenience and possible damage. FIG. 9 shows a modified arrangement designed to overcome this possible difficulty and to unite the cam, plate, ratchet and rollers into a subassembly which can be handled as a unit. In this arrangement the hub portion 35 of the special ratchet (similar to 7) extends upward above the inner flange 36 of the click cam 13 sufliciently to permit its being riveted or staked outward, as shown, to overlie the inner edge of flange 36 rollers can easily be removed and replaced as a unit, the

ratchet being secured to the barrel arbor by a screw 37 (similar to screw 12, but having a groove 37 under the head to accommodate the staked upper end of the hub 35) and the plate being fixed to the frame by the screw 15', similar to screw 15. When this assembly has been removed as a unit, it can be taken apart for cleaning or inspection, if desired, by separating the cam from the plate into which it is press-fitted, which operation will naturally be done under conditions such that there is no danger of the rollers spilling into the watch movement or getting lost otherwise. Sub-assemblies of this type can be made with critical dimensions suited to the requirements of various standard watch movements and may thus readily be installed in place of the normal click arrangements.

Since the riveting or staking of hub 35, as'illustrated in FIG. 9, is a rather delicate operation which must be arrested at precisely, the point where the staked part overthe cam 43 without binding. The cam is held against lies the flange 36 of the click cam without binding on 'it, a further alternative arrangement, shown in FIGS.

10 to 13, may be preferred.

In this form the screw 38 is similar to the screw 12 in FIGS. 1 and 2, while the hub of the special ratchet 39 (similar to 7) extends upward through a central opening in the click plate 40, the upward extension being cut into segment 41 each having a beveled ridge 42 extending radially outward along its upper edge at a height such that the plate 40 is spaced the proper distance above the flat surface of the-ratchet to accommodate rotation by the engagement of two upward projections or prongs 44 with corresponding openings 45' in the plate 40; this engagement may, but need not, be a press fit. The additional holes 46, 47 are used for indexing the plate'in a jig or other assembling device. 1

' 'As a practical matter it is convenient to make the hub portion of the racket as a separate unit 48 (FIGS.

12 and 13) having a cylindrical surface 49 design to be press-fitted into a hole in the web 50 of the ratchet,

where it may be soldered or otherwise fixed to make an integral unit corresponding to that shown at 39 in FIG. 10. The top of the unit is divided into segments (41 in FIG. 11) by means of parallel saw cuts 51, 51, the segments thus formed having suflicient resiliency to permit snap-on assembly as described above. As an alternative to the segmentation of the hub, the necessary resilency can be supplied by providing cuts, radial or otherwise, in the plate 40, extending outward from its central opening. The provision of a sepaarte hub unit makes it possible to use dilfernt materials for the hub and for the web and outer edge of the ratchet (e.g., hardened spring steel for the hub and softer steel or brass for the other portions) thus resulting in an improved product.

Since the smooth and accurate operation of this roller clutch device depends to an important degree on the proper lubrication of the parts, it is desirable to provide rollers which are capable of retaining adequate quantities of lubricant for long periods of time. In FIG. 14 the roller is shown as comprising an annular part 52 which fits loosely on the integrally formed hub 53' of a disk-shaped part 53. The inter-faces between the two parts provide capillary oil-retaining areas from which oil will circulate to adjacent surfaces. The roller shown in FIG. 15 is formed from two parts 54, 54 having flat outer surfaces and lenticular inner facing surfaces, the parts being fixed on an axial metal pin 55. The spacing of the facing surfaces may be sub-capillary in the center and super-capillary toward the edges, so that the lubricant 56 will tend to stay in the narrower areas but can be fed as needed (with the assistance of some centrifugal force when the roller is moving) to adjacent surfaces. The composite roller of FIG. 16 is made up of three flat disks 57 fixed on an axial metal pin 58 with their interfaces spaced to provide capillary oil storage areas. A similar two-layer roller is shown at 59 in FIG. 10. It will be understood that such composite rollers represent a desirable refinement of the plain rollers 18 shown in FIGS. 1, 2, and 9, and that corresponding modifications could also be used instead of the plain rollers 30 and 32 of FIGS. 6 and 7, the rollers in all instances being preferably of jewel material.

Because in cheap watches, the teeth of the ratchet cannot be polished (in view of the cost consideration), and the click spring must be on the strong side to overcome the friction, the noise produced when winding is loud and disagreeable. The feel of winding a cheap watch is uneven and the operation is noisy. The public thus tends to associate the noise of the winding with the cheapness of the watch. The elimination of the noise provided by the present invention will tend to highlight the quality of the product having this construction, resulting not only in an improvement of timekeeper and isochronism, but in the feel the customer will have when he winds his time piece, giving him concrete audible proof that he has a better constructed and more valuable time piece. The click plate 14 will also provide a clear space which can be decorated, polished, engraved, etc. thus putting the repair man on notice that the watch has improved qualities and giving him the trademark and/or other identifying symbols which will enable him to repair and service the watch properly by referring to his text books.

It will be understood that various changes may be resorted to in the form, construction, material and arrangement of the several parts without departing from the spirit or scope of the invention, and hence I do not intend to be limited to the details herein shown or described except as such limitations are included in the claims or may be required by disclosure of the prior art.

What I claim is:

1. In a watch movement, having a frame, a coil spring, an arbor fixed to one end of said spring, a rotatable clutch element fixed to said arbor and having teeth engageable by the teeth of a crown wheel for winding, a cover plate removably fixed to the frame, a second clutch element fixed to the cover plate, one of said clutch elements having a cylindrical surface coaxial with the arbor and the other -of said clutch elements having cam surfaces which are generated by lines parallel to the arbor axis and which surfaces are spaced from and at least in part inclined toward said cylindrical surface, and at least one body of circular cross-section having a diameter less than the maximum distance between said cylindrical surface and the cam surfaces of said other clutch element, said body being located in the space between the cam surfaces of the respective clutch elements and being movable into and out of wedging relation to said cam surfaces, the cover plate being so positioned as to retain the body of circular cross-section in the space between the cam surface and the cylindrical surface.

2. A movement according to claim 1, in which the cylindrical surface is formed on the rotatable clutch element and the inclined 0am surfaces are formed on the fixed clutch element.

3. A movement according to claim 1, in which each of the cam surfaces of said other clutch element includes a portion which is substantilaly coaxial with the cylindrical cam surface and is spaced radially from said cylindrical cam surface by substantially said maximum distance.

4. In a watch movement having a frame and a barrel ar-bor journaled therein, a clutch assembly comprising, a wheel removably engaging the arbor and having an annular recess in one face and a hub, the recess being bounded radially outwardly by a cylindrical wall coaxial with the arbor, a cam of generally annular form lying Within said recess, the periphery of said cam including a plurality of similar cam surfaces each generated by lines parallel to the axis of the arbor and including a portion coaxial with the said cylindrical wall and a portion tapering radially outwardly toward said wall, a cover plate adapted to be fixed to the frame, means interconnecting the cover plate, the wheel and the cam with the plate in a position to cover the annular recess in the wheel, and a plurality of bodies of circular cross-section at least in the plane perpendicular to the axis of the arbor, having a diameter less than the radial distance between the coaxial portion of the cam surface and the cylindrical wall and greater than the minimum distance between the tapering portion of the cam surface and said wall, one of said bodies being located adjacent each cam surface.

5. An assembly according to claim 4 in which the thickness of the wheel, cam and cover plate in the direction of the arbor axis does not substantially exceed the thickness of a normal watch movement ratchet wheel and click.

6. An assembly according to claim 4 in which the cam is locked in free-turning engagement with the Wheel, and the cover plate is in non-turning engagement with the cam.

7. An assembly according to claim 4 in which the bodies of circular cross-section are cylindrical rollers of jewel material.

8. An assembly according to claim 4 in which each of the plurality of cam surfaces extends through at least approximately thirty degrees around the periphery of said cam.

9. An assembly according to claim 4 in which the number of similar cam surfaces around the periphery of the cam is not greater than twelve.

10. An assembly according to claim 4 in which the means interconnecting the cover plate, the wheel and the cam includes a radial projection of the wheel hub to provide an interference fit with a part to which it is inter-' connected.

11. An assembly according to claim 10 in which the radial projection of the wheel hub is formed by staking an end of said hub to overlie an edge of the cam.

12. An assembly according to claim 10 in which the axis of the Wheel and of a size to receive the wheel hub firadial projection of the wheel hub is constituted by a ridge adjacent one end of said hub in a position to overlie an edge of the cover plate.

13. An assembly according to claim 4 in which the cover plate is provided with an opening centered on the and at least one additional opening, the means interconnecting the oover plate,'the wheel and the cam includgaging with the additional opening in the plate.

ReferenceslCited in the file of this patent UNITED STATES PATENTS Robinson June 5, De Long Nov. 5, DiRenzo Dec. 29, Hill et a1. Aug; 7, Cosmos Jan. 8, 7 Hill et a1. Mar. 31,

I FOREIGN PATENTS Germany Aug. 23,

Claims (1)

1. IN A WATCH MOVEMENT, HAVING A FRAME, A COIL SPRING, AN ARBOR FIXED TO ONE END OF SAID SPRING, A ROTATABLE CLUTCH ELEMENT FIXED TO SAID ARBOR AND HAVING TEETH ENGAGEABLE BY THE TEETH OF A CROWN WHEEL FOR WINDING, A COVER PLATE REMOVABLY FIXED TO THE FRAME, A SECOND CLUTCH ELEMENT FIXED TO THE COVER PLATE, ONE OF SAID CLUTCH ELEMENTS HAVING A CYLINDRICAL SURFACE COAXIAL WITH THE ARBOR AND THE OTHER OF SAID CLUTCH ELEMENTS HAVING CAM SURFACES WHICH ARE GENERATED BY LINES PARALLEL TO THE ARBOR AXIS AND WHICH SURFACES ARE SPACED FROM AND AT LEAST IN PART INCLINED TOWARD SAID CYLINDRICAL SURFACE, AND AT LEAST ONE BODY OF CIRCULAR CROSS-SECTION HAVING A DIAMETER LESS THAN THE MAXIMUM DISTANCE BETWEEN SAID CYLINDRICAL SURFACE AND THE CAM SURFACES OF SAID OTHER CLUTCH ELEMENT, SAID BODY BEING LOCATED IN THE SPACE BETWEEN THE CAM SURFACES OF THE RESPECTIVE CLUTCH ELEMENTS AND BEING MOVABLE INTO AND OUT OF WEDGING RELATION TO SAID CAM SURFACES, THE COVER PLATE BEING SO POSITIONED AS TO RETAIN THE BODY OF CIRCULAR CROSS-SECTION IN THE SPACE BETWEEN THE CAM SURFACE AND THE CYLINDRICAL SURFACE.

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