US2920819A - Counting apparatus - Google Patents

Description

Jan. 12, 1960 H. E. G'REENHOW COUNTING APPARATUS Filed Feb. 14, 1958 United States Patent 2,920,819 COUNTING APPARATUS Henry E. Greenhow, Chingford, London, England, asslgnor to English Numbering Machines Limited, Enfield, Middlesex, England Application February :14, 1958, Serial No.'715,371

Claims priority, application Great Britain December 9, 1957 4 Claims. Cl. 235-431 This invention relates to counting apparatus.

' It is an object of the invention to provide an improved counting-apparatus wherein a unit number wheel, which carries the'lowest order of digits,wholly or partly encompasses a mechanism for driving the counting apparatus. ;'It"is another objec't'of the invention to provide 'a drivin'gm'echanism permitting a counting apparatus to be I operated at high speeds whileeliminating the danger of .Wheel is located in position when the driving shaft is stationary. In such counting apparatus, the inside of the unitinumber wheel is slotted axially to provide ratchet teeth. The leading edges 'of these slots are sharply angled to provide engagement for the driving and detent pawls, while the trailing edges have a more gradual slope so that the detent pawls can readily disengage from the -slots=wliile-the wheel is rotating. It is sometimes difiicult with "such a mechanism to count at high speed because the momentum imparted to the unit number wheel may "carry it past its appropria'telocating points. The driving pawls mayalso be disengaged entirely from the internal slots of the unit number wheel if the driving mechanism is subjected to excessive shock. In either case, the counter "reading may be inaccurate.

Accordingly, it is still another object to provide a counting apparatus in which these shortcomings have been removed.

The tensioning of the pawl springs is sometimes increased to overcome such miscounting, but this leads to 'a higher operating torque being required, greater wear between the pawls and the ratchet teeth, and conse quently to a harsh action. The performance and cost of counting apparatus incorporating such ratchet mechanisms Eis also affected by the accuracy and consistency of the springs used.

It is still a further object to provide a counting apparatus which is insensitive to variations in the springs used.

It is yet another object of the invention to provide a counting apparatus the driving mechanism of which is not dependent on the use of individual detent pawls.

It is yet a further object of the invention to provide a counting apparatus requiring a relatively low operating torque but at the same time providing a reliable and positive counting operation.

It is still another object of the invention to provide a counting apparatus of simple construction and capable of being quickly and easily assembled.

These and other objects and advantages of the invenratchet tooth.

rich will become apparent to those skilled in the art from the following description when read in conjunction with the accompanying drawings, which by way of example illustrate a specific embodiment of the invention and in which:

Fig. 1 is an elevational view, partly in section and partly broken away of a counting apparatus having a ratchet mechanism;

Fig. 2 is an elevational view, partly in section and partly broken away showing the ratchet mechanism of the apparatus of Fig. .1 in a position corresponding to the start or finish of a cycle of operation;

Fig. Sis a 'view, corresponding to Fig. 2, but showing the ratchet mechanism in a position just before the end of a ratchet operation stroke;

Fig. 4-is a view similar to Fig. 3, but showing the ratchet mechanism in a position just before the end of a ratchet return stroke; and

Fig. 5 is "a perspective view of the counting apparatus.

A unit number wheel 1 carries numbers about its outer periphery and has a'counterbore with equally spaced axial slots 2. To an extension member 8 of a casing 3 is fixed a stationary first ratchet wheel 4 on the front face of which are cut equally spaced ratchet teeth 5. Mating I with the stationaryrratchet wheel 4 is an intermediate, second, ratchet wheel 6 having projections 7 on its periphery :so shaped and disposed as to be a sliding fit in the axial slots 2 in number wheel 1. Across both faces of :the intermediate ratchet wheel 6 there are provided sets-of equally spaced ratchet teeth 11 and 12, one :set of teeth 11 mating with the teeth 5 on the stationary ratchet wheel "4 and the other set of teeth 12 mating with equally spaced ratchet teeth 13 provided on one face of a driving, third, ratchet wheel 14. The driving ratchet wheel 14 has a hub 15 acting as a bearing for the intermediate ratchet wheel 5. A driving spindle 16, is held against axial movement in both directions by retaining clips 24 which engage in grooves 25 provided in the spindle '16. The spindle 16 is fitted with a pin 17 which locates in a slot-like recess 18 extending from the bore of the-driving ratchet wheel 14. The open end of the casing 3 is sealed by a coverplate 21 and the width of the gap 23 between the inside face of the coverplate 21 and the rearlof the driving ratchet wheel 14 is so arranged as to be slightly greater than the depth of each ratchet tooth, and appreciably less than twice the depth of one In this gap, but so arranged as not to reduce its effective width, is fitted a spring 22 which urges the teeth 'on the three ratchet wheels into mutual engagement.. The counting mechanism is fitted with two stops 26 provided on the case 3, only one of the stops 26 being visible in Fig. l, the stops cooperating with a pin 30 inserted in the spindle 16 so as to restrict the movement of the spindle to an arc of 36 plus a working clearance. A spring 31 is provided for returning the spindle 16 to its initial position after each operation thereof. By omitting the stops 26 and 27, the pin 3t), and spring 31,

the "counting mechanism may be used for continuous rotary movement with each digit position indexed by the ratchet mechanism.

Any rotational movement of the driving spindle 16 is transmitted through the pin 17 to the driving ratchet wheel 14 whose teeth 13 engage on the intermediate ratchet wheel 6, thus imparting rotary movement to the unit number wheel 1 through the peripheral projections 7 on the intermediate ratchet wheel 6. During rotational movement of the driving spindle 16, the teeth 11 on the intermediate ratchet wheel 6 slide up the slope of mating teeth 5 on the stationary ratchet wheel 4 thus imparting axial motion to the intermediate ratchet wheel 6 and the driving ratchet wheel 14 equal to the depth of one ratchet tooth, as permitted by the connection between the driv- Pat ented Jan. 12, 1960' ing spindle 16 and the driving ratchet wheel "14'to the extent of the clearance between the coverplate 21 and the rear of the driving ratchet wheel 14. At theend of the rotational movement of the driving spindle 16, the

ratchet teeth are forced into mesh again under thetensionr of the spring 22 which urges the three, ratchetv wheels" into mutual engagement. l Q

The driving spindle 16 may be rotated in the opposite direction to return to its initial position, under tension of the spring 31 of sufiicient power to overcome the tension of the spring 22. However, if desired,'the.. spring 31 can be omitted, the return of the spindle 16 being efiected by external mechanical means. ,Duringj'the return movement, the intermediate ratchet .wheelg6 is prevented from rotating by the mating" teeth on the stationary ratchet wheel 4. The driving ratchet wheel 14 is rotatably connected to the driving spindle 16 by the pin 11 and its ratchet teeth 13 slide. up the slope of the mating teeth 12 on the intermediate ratchet wheel 6.until the'initial position of the driving spindle 16' is reached when the teeth 13 and 12 of the driving ratchet wheel 14 engagement, an outer barrel-shaped unit number wheel having at least one axial. slot therein, and at least one projection on the intermediate "ratchet wheel and disposed about its periphery to providelocations for and ensure a sliding fit with saidaxial slot.,

and the intermediate ratchetlwheel 6 respectively are T forced into mesh again underthe pressure of the sprin 22.

. It will be seen that for the unit number wheel'l to overtravel, it is necessary for the intermediateratchet wheel 6 to rotate beyond the motion imparted to' itiby the driving ratchet wheel 14. Thelte eth on the intermediate ratchet wheel 6 would then have to slide simulta- 'neously over the crests ofthe teeth on boththe driving ratchet wheel 14 and the stationary ratchet wheel '4, thus imparting an axial motion to the driving ratchet wheel 14 equal to at least twice the'depth of" one ratchet tooth. Since this distance is in excess of the gap 23 provided, the intermediate ratchet wheel 6 would be locked axially between the stationary ratchet wheel 4. and the driving ratchet Wheel 14 before it hadrotated through 72. Any momentum separately imparted to' .the intermediate nated before overtravel causing double counting has taken place."

c It should be clearly understood that the embodiment described and illustrated is given by way of example only;

' Many modifications, omissions and additions .are'possible without departing from the spirit of the invention.

I claim e 2. A counting apparatus, comprising, a stationary ratchet wheel, radial teeth cut across a front face of said stationary ratchet wheel, an intermediate ratchet wheel adjacent said front face, radial, teeth cut across both faces of said intermediate Vratehet wheel with the teeth on one face directionallyopposed to the teeth on the other face (when looking at ther'espective face), a driv-l ing ratchet wheel,radialfteeth ona fac'of said driving ratchet wheel adjacent said intermediateratchet wheel,

-r, said radial teeth on said driving ratchet wheel being similar, but directionally opposed tofthose on, the -stationary ratchet wheel, a, driving spindle co-axiallycarrying said" stationary, intermediate and driving ratchet wheels, means connecting said driving'ratchet'wheelto said spindle so that the driving ratchetwheel is rotatable with, but axially displaceable relatively to said spindle, means for securing said spindle against axial movement relatively to said stationary ratchet wheel, spring meansexerting pressure on said driving ratchet wheel in the direction towards saidfstationary ratchet wheel for ;urging adjacent ratchet teeth on said driving ratchet wheel, said intermediateratchetwheel and said a stationary ratchet wheel into mutual engagement, a unit number ;wheel,an outer rim forming apart of said num- 1 her wheel and surrounding at least in part all of said ratchet wheels coaxially,and means connecting said number wheel to said intermediate ratchet wheel so. that said ratchet wheel 4 and the unit number wheel 1 is thus jelimi- T tionary ratchet wheel, an intermediate ratchet wheel, ra-

on said driving ratchet wheel and similar but'direction- '55 ally opposed to those on the stationary ratchet wheel, a hub on said driving ratchet wheel, said hub carrying said intermediate ratchet'wheel, a driving spindle, a pin car 1 'ried by said driving spindle, said pin engaging a slot'in' abore of the driving ratchet, wheel solthat the driving ratchet wheelrotates with the driving spindle but is allowed to move axially along the spindle, means for securing the said spindle against axial movement, a single number wheel, is rotatable with said intermediate ratchet wheel andsaid intermediate ratchet wheel is axially dis-- placeabl'e relativelytosaid number wheel H v I i ;3. A countingapparatus 'asclaimedin claim2, further including van abutment cooperating with said driving ratchet wheel and arrangedat adistancetherefronrwhich is greater than the depth of each ratchet tooth of said .drivingratchet wheel but less than twice such depth for preventing overtravel leading to double counting of said unit number wheel by said driving ratchetwheel abutting against said abutment. e p 4 4, Accounting apparatus as claimed claim 3, including a casing, and a cover plate on said casing, said abutment being formed by said cover plate, said spring means being located between said cover plate and said driving ratchet wheel and bearing against said cover plate and ;said driving ratchet wheel, f 1 7 References Cited in the file'of thisipatenta p v UNITED s'rAr s PATENTS, fl i 1,161,171

Vertunni Nov. 2 3, 191s 2,046,810 Cannon July 7, 1936 E QNPA NT t 697,257 r Great Britain Sept..16,.1953

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