US2443558A - Mainspring tension indicator for watches and similar mechanisms - Google Patents

Description

June 15, 1948. Q U FRENNESEN 2,443,558

' MAIN SPRING TENSION INDICATOR FOR WATCHES AND SIMILAR MECHANISMS F1ed.Ju1y 5, 1945 Patented June 15, 1948 MAINSPRING TENSI WATCHES AND SI ON INDICATOR FOR MILAR MECHANISMS Carl U. Frennesen, St. Paul, Minn. Application July 5, 1945, Serial No. 603,328

5 Claims. 1

This invention relates to means operable by the main spring of a watch or similar mechanism for indicating on a dial or scale the state of tension of the spring and/or for stopping an automatic spring winding device when the spring is fully Wound.

It is an object of my invention to provide simple, compact and efficient mechanism of this class whereby an observer is enabled to determine at a glance the state of tension of the main spring of a clock, watch or other mechanism having a rotary {spring-actuated member and a rotary Winding member disposed in parallel and coaxial relation to Ithe spring-actuated member.

A further object is yto provide a device of the class described adapted to be applied as a simple attachment or addition to common types of Watch mechanisms wherein a. main spring-driven member is disposed coaxially with andin parallel relation to a wheel for Winding the spring.

A particular object is to provide mechanism of the class described wherein movement is transmitted to an oscillatable arm from both the spring-driven member and winding wheel therefor through 4the medium of teeth of spiral form and a toothed pinion which rotates about its own center and is movable substantially radially of the main spring axis while in mesh with the spiral teeth on the driven member and winding wheel.

Other objects will appear and be more fully pointed out in the following specication and claims.

Referring -to the accompanying drawing which illustrates my device by way of example and not for the purpose of limitation, as applied to a spring-operated watch mechanism of common type:

Figure 1 is a front view of the watch having a preferred form of my indicator mounted thereon and with -a portion of the face cover and dial broken away to show parts otherwise concealed;

Fig. 2 is a back view of the mechanism with the cover removed;

Fig. 3 is a part side View and part section taken on the line 3 3 of Fig. 1;

Fig. 4 is a. fragmentary, somewhat diagrammatic, enlarged vertical section taken approximately on the line 4-4 of Fig. 2;

Fig. 5 is a detail plan view of the spiral tooth carried by the ratchet wheel, looking in the direction indicated by the line 5-5 of Fig. 4 and with 'the axial shaft shown in section;

Fig. 6 is a part plan view and part section taken approximately on the line 6 6 of Fig. 4, and

Fig. 7 is an enlarged plan view of a portion of the arm carrying the pinion and with the supporting arbor therefor shown in section.

As shown in the drawing, the watch has a case indicated generally by the numeral 8, a removable back cover 9 and a transparent face cover or crystal I0. The movement is supported within the case on aback plate I I and parallel front plate I2 and there is a dial I3 supported in front of the plate I'2. These plates and the dial are rigidly connected together and to the case in suitable manner. A winding knob I4 projects from the case to be manipulated to turn a gear I5 through suitable connecting means, including a stem and bevel gearing. The teeth of the gear I5 mesh with teeth formed on the periphery of a ratchet Wheel I6 and this wheel is fixed on a shaft I1 having bearings in the -plates II and I2 and connected to the main spring of the watch (not shown) within the main spring barrel indicated by the numeral I8. The main spring is of the common spiral form and has its inner end connected to the shaft Il and its outer end to the barrel I8 so that the latter is turned in one direction (clockwise, Fig. 6) when the spring is under suicient tension. Peripheral teeth I9 on the barrel I8 are adapted to drive a suitable gear train to actuate, in the usual manner, the hands 20 indicating the time by reference to the graduated dial I3. It will be evident that the watch movement hereinbefore described is of common type illustrative of suitable environment for the preferred form of my improved indicator presently to be described.

I provide an arcuate scale 2I (Fig. l) on the dial I3 where it may be readily observed through the crystal I 0 and a small hand 22 to indicate the tension of the main spring by reference to the scale 2|. The latter is graduated and provided with indicia indicating at one end that the spring is fully wound and at the other end that it is unwound or has insuiiicient tension to operate the watch. There are also intermediate indicia abrding readings in fractions of full tension. The hand 22 is iixed on a pin 23 having a bearing in the front plate I2 and a small toothed pinion 24 is also fixed on the pin '23. This pinion is in continuous mesh with a toothed segment 25 which is integral with an arm 26 and the latter is fixed on an end of an arbor 2l. Bearings for the arbor 21 are formed in the plates I I and I2 so that Ithe arm 26 is adapted to oscillate upon the plate I2 about the axis of the arbor 2l. Details of the hand operating mechanism and scale 2l may be varied widely Within the scope of the present invention.

A second arm 28 is connected to the arbor 21 and extends between the opposed faces of the ratchet wheel I6 and main spring barrel I8. Rotatable on the end of the arm 28 remote from the arbor 21 is a small toothed pinion 29, disposed with its axis of rotation parallel to and midway between the opposed .faces of the ratchet wheel and drum. This pinion is movable bodily with the arm `2B in an arc having its vvcenter at the axis of the arbor 21, this arc being approximately radial to the shaft |1 (see Fig. 6).

Formed on the face of the barrel I8 to mesh with the pinion 29 is a spiral tooth 30 havingits convolutions uniformly spaced radially .to correspond with the pitch of the teeth of 'the pinion 29. Another spiral tooth 3| is formed fon the ,Y

opposed face of the ratchet wheel the pinion 29 in a similar manner. VAs lindicated in Figs. 5 and 6, the spiral tooth 3| winds .in the reverse direction as compared with the tooth 3|). That is to say, vfrom its inner end 31a .the tooth 3| extends counter-clockwise .and Vspirally outward, whereas, .the tooth 39 extends clockwise from -its -inner end Sta outward. The outer kends of the teeth 3@ and v3i are indicated respectively by the numerals T3817 and V3H). As further indicated in Figs. 4 and `6, lthe convolutions of the tooth 30 Acontinue -outwardsomewhat beyond Athe outer convolution 4'of the :tooth el rand the ,con-- volutions of the latter approach the shaft l1 more closely than those of the tooth 3Q. Otherwise these teeth are vopposite one ,to the other. lTlf-1e pinion 2S in its movement `about the axis of the -arb'or @2.1 oscillates substantially radially -oi the `spiral -teeth 30 and .3l and is in continuous mesh with bothof them.

The connection between the arbor 21 and arm 2.8 is preferably or the :type shown in detail vin Fig. l7. Thus .the arbor Yis `of kelliptical .shape in cross section yand engages the iarm 28 in ,a substantially square opening 32 in said arm.V A .slit 33 fbifurcates the end :portion of `said :arm which is constructed 'from sufficiently :resilient material so 1that the respective end sportions :spring apart and permit slight oscillating movement of the arm relative to the arbor when the arbor is stopped through its connection with the-arm 25. Toflimit oscillating movement :of the arm .21.5, as indicated in Fig. 1, it may be formed 'toextend between stop pins Sil and projecting from vthe face of 'the supporting lplate I2. An angularly `bent end portion 38 `may -alsobe extended through an opening 35 in the plate l2 to aiiord'astop zfor 'the self-winding mechanism incase the watch is provided with automatic winding mechanism.

In operation. when the watch is-*wound by Vmeans of -the `knob M, the ratchet wheel H3 is turned in a clockwise direction (Figs. 2 and '5). Assuming that `'the main spring is in, fully unwound or low tension condition v'the .hand .-22 will point Ato Vthe Zero mark on the scale 2i and the corresponding position of .the 'pinion 29 will be at thel inner extremity scf the -tooth :34. Now as the watch fis wound the barrel it remains sub# stantially stationary the 4clockwise rotation of lthe wheel It by means of the Itooth 3| causes the vpinion 2e vto .turn about itscenter and :to be moved substantially radially outward relative 'to the shaft .|1. During this movement the pinion '29 merely vrolls in mesh with the convolutions =of Ui to mesh with the 'toothed and the 4arm 2li turns the arbor .'21 K and actuates the yarm 2t, tooth .segment 25 `and .piniont =tovmove the hand v22 -to the right (Fig. 1) `over the scale 2|. lWhen .the main spring has been substantially fully wound in this mannerthe 4 arm 26 is stopped by the pin 35 with the hand 22 indicating the fully wound condition.

Overriding by the watch movement with respect to this fully wound position of the arm 26 is permitted by so positioning the outer end 31h of the tooth 3| as to cause it to release the pinion 29 before the spring has been wound excessively tight. With the indicator hand 22 in the fully Wound position the main spring slowly rotates the barrel i8 in a clockwise direction (Fig. 6) while the wheel H and its tooth 3| remain stationary. This causes the spiral tooth 30 to turn the pinion 29 and to oscillate the arm 28 radially yinward toward the shaft l1 with the axis of the arbor 21 as the center. Consequently the arbor 21 reverses the movement of the arm 26 which, through the segment 25 and pinion je, slowly moves the hand 22 to the left along the scale 2| from the fully wound position.

To permit overriding by the watch movement relative to the zero position of the hand 22, the inner end 36a of the tooth S@ is so positioned Ithat it disengages the pinion 29 and stops inward movement kof ,the arm -28 at a suitable point in the cycle of operation. Relief is also aorded by the springing apart of the biiurcated yend portions of the arm 23 relative to the elliptical arbor 27 thus allowing the arm 28 to swing slightly relative to the arbor, as indicated in dotted lines in Fig. 7. This feature is used to spring bias the arm 28 in an outward direction when released by the end @to of the tooth 3@ Aand in an inward direction when `released by the end 3|b of the tooth 3|. Thus the tendency of the arbor 21 to spring back to its diagonal position -in the square opening 32 causes the pinion 29 to'rspring radially, to the extent of the radial pitch, outward when released by the inner end Sila of the tooth 3|) and inward when released by the end 3|b of the tooth 3l. The effect of this is -to insure properengagement of the vpinion 29 with the spiral teeth at all times.

'It will be evident that my device occupies space which is available within the cases of ordinary watches and does not require rearrangement of the watch mechanism. The teeth 3B and 3| are preferably out on the faces o1" the barrel t8 and wheel it respectively, although insome watches it lmay be feasible 4torprovlde these spiral teeth on separate discs or as separate spirals attached to the faces respectively of spring driven and winding members. For `watches provided with self-winding de.- vices the end portion 3S of the arm 26, when in its fully wound position constitutes `a stop for the oscillating weight, thereby'guarding against excessive winding and undesirable operationfof the automatic winding movement. This stop feature may be used with or without the indicator hand and scale but it will Abe evident that the indicator shows when hand winding is necessary even where automatic winding mechanism is provided.

Havingdescribed my invention, what I claim as new and desire to protect by Letters Patent is:

1. 'In a spring tension indicator for mechanism having a `rotary spring-driven member, a spring for rotating said member and a rotary spring Winding member disposed in spaced parallel and ycoaxial relation to said spring-driven member, .the improvements which comprise, teeth of spiral form disposed on the respective opposed liaces of said .'members, a pinion movable substantially radially of the axis of .said members between their opposed faces and Shaving teeth disposed to mesh simultaneously with the spiral teeth on said members, the tooth on said winding member being formed to move said pinion substantially radially in one direction during the spring winding rotation of said member, the tooth on the spring-driven member being' formed to move said pinion substantially radially in the reverse direction during the normal rotation of said spring actuated member and said spiral teeth -being of relatively unequal radial extent at their outer and inner ends to permit the stopping of radial movement of the pinion While rotation of the spring-driven member relative to the winding member continues, means including a scale and hand for indicating by reference to said scale the state of tension of said spring and means connecting said pinion to said hand for actuating said hand relative to said scale.

2. The indicator mechanism according to claim 1 in which stop means are provided to limit the movement of said hand at the opposite ends respectively of said scale and said means connecting said pinion to said hand includes means associated with said stop means for resiliently retaining said pinion in engagement with the spiral teeth during the reversal of movement of the pinion.

3. The indicator mechanism according to claim 1 in which said means connecting said pinion to said hand comprises an arbo-r disposed in Cil parallel relation to the axes of said members, an arm carried by said arbor and extending -between said members, said pinion being rotatably mounted on said arm to impart oscillating movement thereto and means operatively connecting said arbor to said hand.

4. The indicator mechanism according to claim 1 which includes means for spring biasing the pinion radially inward when positioned at the outer extremity of its movement and radially outward when at the inner extremity of its movement.

5. The indicator mechanism according to claim 1 which includes an arm pivoted to oscillate in a plane parallel to the opposed faces 0f said spring-driven and winding members and operatively connected to said pinion and means for limiting oscillating movement of said arm to an arc corresponding approximately to the radial movement of the pinion.

CARL U. FRENNESEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 790,512 Mazer May 23, 1905 790,513 Mazer May 23, 1905

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