US2238920A - Counter resetting device - Google Patents

Description

Patented Apr. 22, 1941 2,238,920 COUNTER RESETTING DEVICE Victor C. Studley, Newton, Mass, assignor to Waltham Watch Compa y, Waltham, Mass, a

corporation of Massachusetts Application January 20,1939, Serial No. 251,996

Claims.

The present invention relates to counters of the type which consist of number wheels rotatably mounted side by side on a shaft, which are reset to zero position by rotation of the shaft, such shaft having a longitudinal groove or its equivalent forming a shoulder in the same zone with each of the number wheels, and each wheel having a spring actuated resetting pawl adapted to pass over the shoulder during the rotation of the wheel in counting, and to lodge in front of the shoulder and be propelled thereby when the shaft is turned for resetting. This type of counter has long been known and used. The principle of its resetting means has the desirable and recognized advantage of ability to place all of the number wheels in zero indicating position in the course of a single rotation. But the realization of this principle requires that there be no failure of the shaft to pick up any wheel 'which may have been advanced, in aprevious counting action, to position where its zero character is exposed to view.

Most commercial counters are made with pivot clearances and backlash of forwarding. gears sufllclent to ensure easy assemblage and light running, wherefore it usually happens that the wheels of higher order, when'advanced bytheir tens carrying means to change their indication from nine, to zero, stop more or less short of the position in which their numerals are in exact alinement or register with the numerals of the wheels of lower orders. Hence, in the absence of v and described in the following specification.

In the drawing Fig. 1 is a partial section and partial elevation I of a counter in which thisinvention is embodied;

Fig. 2 is a cross section on line 2-2 of Fig. 1, represented on an enlarged scale showing the resetting means of one of the number wheels and the tens carrying pinion between that wheel and the one of next higher order, the wheel represented being in a position other than zero indicating position;

Fig. 3 is a similar view but showing the wheel in the zero position;

Fig. 4 is a similar section taken on line 4-4 of Fig. 1 showing the means which transmits incorrective provision, the resetting pawls of such higher order wheels fail to engage with the adjacent forwarding shoulders of the .resetting shaft, and they are not advanced if .the shaft is turned while they are so positioned. A wheel which falls to be thus advanced is propelled a step ahead when the adjacent lower order wheel comes to the zero position. This necessitates turning the resetting shaft through another rotation to bring all the wheels to zero .or,',if the failure to function is not noticed by the operator, the counter is incorrectly reset. I

Counters have been heretoi'ore made in which, to prevent the occurrence of such an error, means are provided to turn the resetting shaft backward a few degrees after it has completed its resetting rotation. Thus in resetting, the shaft is. turned through360 plus the angle of such backward movement, and after, being released by the operator, the means [provided for the purpose automatically turn it back through the p.escribed angle.

It is the object of this invention to eliminate termittent motion from the wheel of lower order to the one of higher order but permits the higher order wheel to be advanced in resetting;

Fig. 5 is a fragmentary view similar to Fig. 3 showing the manner in which my invention operates in the case of a wheel which has been advanced approximately to zero position before resetting.

Like reference characters designate the same parts wherever they occur in all the figures.

The counter here shown consists of four number wheels 5a, 5b, 5c and ,id, and typifies any counter having more than two wheels. All the wheels are mounted rdtatably on a shaft 6 which is itself rotatable for advancing the wheels into zero indicating position but is normally restrained from rotation by frictional resistance sufficiently powerful to hold it stationary when the wheels are turned in counting. Between each wheel of lower order and the adjacent one of higher order is an intermittent tens carrying mechanism consisting of a disk 7, fast with the lower order wheel, having a circular circumference and a single notch 8, forming a gear tooth space; a mutilated gear 9, also fast with the lower order-wheel, having two teeth I0 which register with the flanks of the notch 8; a carrying pinion ii rotatably mounted on a shaft 52 at one side of the number wheels and parallel to the shaft 6; a complete gear wheel i3, rotatable independently of the number wheels, meshing with the pinion H; and a pawl l4 carried by the gear wheel l3 and biased by a spring l5 so that its toe is adapted to engage any one of a number of internal teeth or shoulders 55, corresponding to internal ratchet teeth, within the circumference of the adjacent higher order wheel. Alternate teeth I! of the pinion engage the circumference of the disk I on the lower order wheel and are driven by the teeth Ill and notch 8 to turn the pinion through the angle subtended by two of its teeth whenever the disk passes the pinion. This action takes place when the number indication of the wheel changes from 9 to zero. Engagement of the pinion teeth I! with the circumference of the disk I locks the pinion against rotation at other times. The liltermediate teeth l8 of the pinion are cut away at one end short of the disk l and act to propel the gear wheel l3 through 6 of a rotation whenever the pinion is so turned. The pawl H is so located, as shown in Fig. 4, as to advance the number wheel or higher order when the gear wheel I3 is turned, but to yield and permit in-- dependent movement of the wheel when the latter is propelled by other means in the same di rection. Each assemblage of number wheels, disks and propelling gear wheel is mounted on a sleeve or bushing l9 which surrounds the shaft 6.

The resetting shaft 5 is formed with a shoulder 20 in th zone surrounded by the disk I of each wheel. Preferably one continuous shoulder extending through and between all of these zones 1 is formed by cutting a V-shaped groove in one side of the shaft through so much of its length as lies within the number wheels. This is the usual mode of making propelling shoulders in resetting shafts of the type here shown, but th invention is not limited thereto. The resetting pawl 2! of each number wheel is located in a recess 22 of the associated disk I, and is provided with a circular end portion 23 fitting a complemental socket portion 24 in one end of the recess, while its opposite end protrudes and is adapted to enter the groove in the shaft. A spring 25, made of wire or iiat spring stock, is bent so as to fit one side and the opposite ends of the recess and to form two spring elements 26 and 2?. The spring element 26 bears against one sided the circular pivot portion 23, holding the latter in the bearing socket 24, and the other spring element bears against the outer edge of the pawl pressing its toe toward the shaft and into the groove in the side of the latter when in register therewith. The pawl is so correlated with the numerals on the number wheel, the position of the wheel when accurately located to show the zero indication and the position of rest of the resetting shaft, that it enters fully into the notch in the shaft and engages the shoulder at at the inner limit thereof when the wheel has been brought fully to zero position. This is the relationship shown in Fig. 3 of the drawing. When the wheel is turned in its counting rotation, the shaft being then stationary, it rotates in the direction of the arrow in 2 and the pawl is withdrawn from the notch and rides on the surface of the shaft until the wheel reaches approximately the zero position.

For resetting the counter at zero, the shaft is turned by suitable means, such as a key applied to its end to (Fig. 1), in the same direction and corresponding position of the lowest order wheel,

is accomplished in accordance with this invention by novel characteristics of construction and cooperative combination of the forwarding shoulder and pawl. The invention comprises means to insure engagement of the forwarding shoulder with all wheels of higher order which have stopped in such an approximation of the zero position.

The toe or tip 28 of the pawl swings about its pivot axis (the center of the circular portion or head 23) in an are designated by the dotted line 29 in Fig. 3. The shoulder 20 is so disposed that, when brought to engage at its innermost limit with the toe of the pawl, it diverges from this arc. Such divergence is at least as wide at the outer extremity 30 of the shoulder as the lag angle of the counter. In other words, the angle about the axis of the shaft between the point 30 and a point equally distant from such axis on are 29 is equal to, or greater than, the lag angle. The expression "lag angle" as here used means the angle between the actual stopping point of a higher order wheel in zero indicating position and its position of true numeral alinement (parallel to the axis) with the wheel of lowest order. It is of course larger, on account of accumulated backlash, in the case of wheels more remote, than of those less remote, from the lowest order wheel. The arc concentric with the axis from the outer extremity 30 of the shoulder to the path 29 may be called for the purposes of this description the lag angle are because it compensates for the lagging of the number wheel. For practical purposes it is necessarily somewhatlarger in angular degrees than the lag angle of the corresponding wheel. While it is possible to make such lag angle arcs of different values for different wheels, it is preferable in the interest of uniform-- ity to make it of the same value for all wheels and larg enough to compensate for the lag of the highest order wheel in any given design of counter. I have found that an arc of 14 is sufficient to compensate for the maximum lag in a four wheel counter having the amount of backlash common in commercial mechanisms of this character. But where the instruments are made with .greater or less precision and accuracy than the common order, the lag angle arc may be less or greater than this value.

The utility of the lag angle arc is illustrated by Fig. 5, which shows the position of a high order number wheel when it has been brought by its propelling mechanism to change its indication from nine to zero in normal counting action. On account of the lag described, its forwarding pawl has not been advanced so far as the pawl of the lowest order wheel when in zero position, and s0 is unable to pass to the bottom of the resetting shoulder. But the divergence of the shoulder from the path of the pawl enables the pawl to pass within the outer extremity of the shoulder, whereby it may be advanced by rotation of the resetting shaft if the counter is reset before this number wheel has been moved to indicate a higher number. This figure shows the condition with the wheel having substantially the greatest angle of lag. Where the lag is less, the pawl will pass nearer to the inner limit of the shoulder in corresponding circumstances. But in any case no more than one complete rotation of the shaft is needed to place all of the number wheels in zero alinement, including those showing zero prior to resetting as well as those showing other numerals.

In the illustration here given, the axis of the pawl is located as near as practicable to the axis of the counter in order to obtatin a wide divergence of the path of its toe from the shoulder. The latter, in this illustration, is approximately radial to the shaft and extends wellinward toward the axis of the shaft, but its inner limit is far enough away from the axis to afl'ord ample leverage for resetting the wheels of which,the pawls are engaged with such inner limit. Indeed, the complete elimination of springs or other means for turning the shaft backward after resetting has removed most of the resistance to resetting encountered in those instruments where shaft backing springs are used. The end edge of the pawl adjacent to the toe is inclined away from the shoulder, as shown in Fig. 3, in order to afford clearance enabling its entrance to the' inner limit of the shoulder when the relative positions of the wheel and shaft make such en.- trance possible. The pawl ismade with considerable width adjacent to its toe extremity in order to provide stiffness insuring against bending. However, the precise proportions here shown are not essential, and various modifications as to the minimum leverage, the shape and outlines of the shoulder and pawl, and the extent of the lag angle arc may be made within the scope of the invention. The limiting factors are that the minimum leverage must be great enough to cause resetting movement of the wheels when the shaft is turned, and that the outermost part of the shoulder must not be inclined at such a large angle to the radial line of the pawl toe, when in a relationship like that shown in Fig, 5, as to crowd the pawl out of engagement. Within these limits, the shoulder may have any shape and an gularity desired.

The spring element 26 is an important contributing factor to the accomplishment of my object. It constantly holds the head against the wall of the socket, taking up all clearance and looseness between the mating surfaces of these parts. nearly coincident with the line from the toe to the pivot center of the pawl, that the toe is always maintained at an invariable distance from the inner wall of the socket. The line of its action, moreover, is substantially tangential to the path in which the pawl revolves with the wheel about the axis of the latter and its pressure effeet is in the direction of such revolution, Thus the pawl toe is always maintained so that it will engage with the resetting shoulder in the same manner whenever the wheel and shaft are brought into the same relative position. This assures the uniformity and effectiveness of the lag angle arc hereinbefore defined.

What I claim and desire to secure by Letters Patent is:

1. In a counting mechanism having a normally stationary but rotatably mounted shaft, two or more wheels rotatably mounted upon said shaft, at least one of which bears consecutive numbers,

means operative as one of said wheels makes one And the direction in which it acts is so.

complete revolution in one direction for rotating the wheel of next higher order one step in the same direction, and a pawl pivotally mounted upon each of said wheels operative to be engaged by a driving shoulder formed by one wall of a. groove in said shaft, said driving shoulder having a length less than the radius of said shaft, the improvement which comprises arranging the effective length of each pawl and the position of its pivotal axis with relation to the length of the said shoulder so that said shoulder diverges from its inner limit outwardly from the path of movement of the extremity of each pawl by an angle at least as great as the lag angle of the wheel carrying the pawl due to backlash, thereby assuring that each pawl will be picked up and all wheels accurately reset upon rotating said shaft in said direction not more than one revolution.

2. In a resetting mechanism for a counter, a rotatably mounted resetting shaft having a longitudinal groove, two or more wheels rotatably mounted upon said shaft, at least one of which bears consecutive numbers, means operative as one of said wheels makes one complete revolution in one direction for rotating. the wheel of next higher order a fractional part of a revolution in the same direction, a pawl pivotally mounted upon each of said wheels operative to be engaged by the driving shoulder of said groove, the depth of said driving shoulder being less than the radius of said shaft, the effective length of each pawl and the position of its pivotal axis with relation to the depth of said shoulder being such that said shoulder diverges from its inner limit outwardly from the path of movement of the extremity of each pawl by an angle at least as great as the lag angle of the wheel carrying the pawl due to backlash, thereby assuring that each pawl will be picked up and each wheel returned to its initial position upon rotating said shaft in said direction not more than one revolution.

3. In a resetting mechanism, arotatablymounted resetting shaft having a longitudinal groove, a series of rotatable wheels rotatably mounted upon said shaft, means for rotating one wheel one step when the next Wheel has completed a revolution in one direction, a pawl pivotally mounted upon each of said wheels operative to be engaged by 'one wall of said groove forming a driving shoulder, the depth of said driving shoulder being less than the radius of said shaft, the eiTective length of each pawl and the position of its pivotal axis with relation to the depth of said shoulder being such that the path of movement of the extremity of each pawl from the inner limit of said shoulder outwardly diverges from said shoulder by an angle at least as great as the lag angle of the wheel carrying the pawl due to backlash, thereby assuring that each pawl will be picked up and each wheel returned to its initial position upon rotating said shaft in said direction not more than one revolution.

4. In a mechanism as described by claim 3, a spring mounted upon each wheel, one portion of the spring being operative to urge the extremity of the pawl into said groove and another portion of the spring being operative to urge the pawl away from said driving shoulder in a direction along the effective length of the pawl.

5. In a resetting mechanism, a rotatable shaft,

a plurality of wheels of successive orders rotatably mounted thereon, means for advancing one wheel one step when the next lower order wheel has made a complete revolution in one direction, a pawl pivotally associated with each of said wheels operative to be drivingly engaged by a wall v surface-0f a groove in said'shsft, the patb. of

' relatively diverging from said groove wall surface by an amount at least correspondmg'wlth the backlash lag angle or the wheel associated with said pawl, and spring means urging said pawls towards said shaft, thereby assuring that each pawl will be picked up and each wheel returned to its original starting position upon not more than one revolution of said shaft in the said d1- VICTOR c. STUDLEY.

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