US2904250A

US2904250A - Bi-directional counter mechanism

Info

Publication number: US2904250A
Application number: US532414A
Authority: US
Inventors: Karl A Allebach
Original assignee: Northrop Grumman Corp
Current assignee: Northrop Grumman Corp
Priority date: 1955-09-06
Filing date: 1955-09-06
Publication date: 1959-09-15
Anticipated expiration: 1976-09-15

Description

Sept. l5, 1959 K. A. ALLEBACH 2,904,250

IDnf EcT1ormrd COUNTER MECHANISM Filed sept. e, 1955 E 453 y ill nh. $37

- 4; 4 49 l "27., l'fgi. 505

AUnited States Patent G BLDnzEctnoNAL COUNTER MECHANISM Karl A. Allebach, Beverly Hills, Calif., assignor to N orthrop Corporation, Hawthorne, Calif., a corporation of California Application September 6, 1955, Serial No. 532,414

1 Claim. (Cl. 23S-91) This invention relates to means for operating mechanism such as counters in which each operating movement of said means is effective to turn the counting wheel an exact distance and then return to initial position ready for the next operating movement, preferably in either clockwise or anti-clockwise direction.

The invention is particularly designed for usein electrically operated counters although not necessarily restricted thereto, and will hereinafter be described as incorporated in an add-subtract counter operated by electrical pulses which may cause the counting wheels to rotate in one direction to add `one digit at each signal or to subtract one digit at each signal when rotated in the opposite direction, the number shown by the counting wheels therefore being the sum or difference of the signals received by the counter assuming the number shown was zero at the commencement of a counting operation.

It should be noted that with minor modification the novel mechanism of the invention may be used to provide operation of a one-way counter.

Some electrically operated counters have to be designed to operate accurately at high speeds and therefore the operating means must be light, free from unnecessary friction and positive in action, which necessitates absence of backlash and a minimum of parts.

In order to provide a counter operating member that will satisfy the requirements outlined it is an object of the invention to provide operating means which may be readily incorporated in, or substituted for parts at present provided in mechanism having rotary parts operated by electrical signals, such as one-way, oradd-subtract counters.

Another object of the invention is to provide operating mechanism effective to rotate a part in accordance with electrical signals, which operating mechanism comprises few parts and is light in weight as Well as positive in operation.

Still another object of the invention is to provide operating mechanism of the kind described in which friction is reduced to a minimum so that the power required to actuate the mechanism is very small.

A further object of the invention is to provide operating mechanism of the kind described effective to positively limit th'e angular displacement of a part intermittently operated by the mechanism in response to electrical pulses or signals, and to hold the part against movement between operative movements of the mechanism.

With the above objects in view the invention comprises operating means for a counter having a housing, a train of counting wheels mounted for rotation on a shaft fixedly supported in said housing, a star wheel fixed to the digit Wheel `of the train and an actuating member mounted in said housing, said operating means including: a yoke pivoted in said housing and oscillated by the actuating member; pawl means pivoted on said yoke and adapted to be engaged with an individual tooth of the star wheel at each oscillation of the yoke; means limiting the pivotal movement of said pawl means in one direction relative to the yoke; means limiting the amount of rotative movement of the star wheel at each oscillation of the yoke; and resilient means holding the detent means in rest position against the means limiting movement thereof.

In the drawings:

Figure 1 is a perspective view of an add-subtract counter fitted with the operating means of the present invention, a two-part housing being shown separated with parts of housing wall broken away to show the arrangement of certain parts of the mechanism.

Figure 2 is a fragmentary detail drawn on an enlarged scale on the line 2 2 of Figure 1 showing the operating means of the invention in the rest position.

Figure 3 is a view similar to Figure 2 but showing the operating means at the end of an operating movement in counter-clockwise direction.

Figure 4 is a cross section on the line 4-4 of Figure 1 drawn on an enlarged scale and seen in the direction of the arrows 4, 4 in Figure 1, showing electrical parts of a commercial form `of counter, which parts do not form part of this invention, but are illustrated for the better understanding of operation of the novel operating mechanism of this invention.

Figure 5 is a fragmentary detail of parts shown in Figure 3, looking in the direction of arrows 5, 5 in that figure.

In the drawings the parts of the counter to which the operating member is applied will first be described, this counter being a commercial product but the parts shown being necessary to understand the function of the operating means of this invention.

The counter two-part housing is indicated generally at 10, the front portion 11 of the housing having the usual counting wheels 12 arranged therein mounted on sleeves 13a on a shaft 13 supported at its ends in the housing. The usual mechanism (not shown) is provided for moving the tens wheel 14 one digit for each ten movements in one direction of the units wheel 15 and so on. The number wheel markings me visible through a window held in the frame 16 on the fro-nt wall of the front portion 11 of the casing.

The back portion 17 of the casing contains a pair of fiat `

electro magnets

18, 19 with their pole pieces 20, 21 (Figure 4), respectively, spaced apart. A flat fiapper 22 is arranged between the pole pieces 20, 21 and is pivoted on a shaft 23 supported at its ends in the rear half 17 of the housing. A spring 24 is arranged to hold the flapper 22 normally midway between the pole pieces 20 and 21. The flapper is of hollow construction and of little weight so that it is instantly snapped toward whichever electro magnet is energized. A pin 25 is Abrazed into the free edge of the fiapp'er 22 at one side. All the parts so far described are parts of a commercial product and form no part of the invention.

The operating means of this invention are mounted on a shaft 26 parallel to shaft 13 and supported at its ends in the walls of the front portion 11 of the housing, the operating means engaging with a l0-point star Wheel 27 fixed on the sleeve 13a on which the digit counting wheel is mounted, and also forming part of the commercial counter.

The operating means comprise, in the case of an addsubtract counter, an arcuate yoke 28 mounted on a sleeve 29 free to turn on shaft 26 between the digit counting wheel and the adjacent wall of the housing. Extending outwardly from the yoke 28 a slotted oscillator member 30, formed integral with or secured to said yoke, is provided with a slot 31 in which is received the pin 25 of the flapper 22. The yoke 28 is thus oscillated in accordance with the movements of the flapper 22.

At the ends of the

yoke abutments

32, 33 are provided, serving as stops for pawls 34, 35 which are pivotally mounted on

pins

36, 37 secured in the ends of the yoke. Springs 3S, 39 resiliently hold pawls 34, 35 against

stops

32, 33 in the rest position of the yoke.

As clearly shown in Figures 2 and 3, the pawls 34,k 3S are provided with rounded ends 4t), 41 which when the yoke is oscillated engage the teeth of the star wheel 27 about midway of their length and roll toward the root portion of the tooth with a line contact with the surface of the tooth, causing a 36 rotation of the star wheel, the pawl in turn moving away from the abutment to which it is pivoted and stressing its associated spring 3S or 39. The movement of the star wheel is stopped by engagement of the back of the following tooth with the

abutment

32 or 33; it should be noted that these abutments serve the double purpose of positioning the pawls 34 and 35 in the rest position and also as positive stop means preventing movement of the star wheel 27 beyond 36 degrees, as well as further movement of the yoke. If desired

abutments

32, 33 may be formed as indicated in dotted lines in Figure 3 at 32a, 33a so that they contact between two teeth thus positively locking the star wheel for an instant against rotation in either direction, thus preventing any bounce back of the star Wheel.

At the termination of the electrical signal the flapper 22 returns to neutral position carrying oscillator member 36 also toward neutral or rest position. The movement of member 39, which is rigid with yoke 28, toward neutral is aided by whichever

spring

38 or 39 was flexed by movement of a pawl 34 or 3S, the spring drawing the pawl toward

abutment

32 or 33 causing the rounded end of the pawl to ride up the back of the following tooth while raising the end of the yoke 23 to which the pawl is pivoted until the rounded end of the pawl clears the tip of the tooth. Since the yoke 23 is symmetrical and balanced about its pivotal axis, very small forces are required to move it.

in order to ensure that the star wheel retains the position to which it is moved by each oscillation of the yoke 28, a plate 42 is guided for vertical movement in a plane normal to the axes of the

shafts

13 and 26 by slots 43, 44 in the ends of the plate, the edges of which slide on the

shafts

13 and 26, respectively. The plate 42 is positioned against yoke 28 by peripheral grooves in the sleeves 13a and 29 carrying the star wheel 27 and yoke 28. A ledge 45 is machined to project from the face of the plate 42 and of a length to extend over two of the teeth of the star wheel below the center of the yoke the ledge 45 constituting an aligning element for the star wheel teeth. The plate is resiliently urged toward shaft 13 by a pair of light springs 46, 47 under tension between a stud 48 (Figure 2) screwed into the ledge 45, the head of the stud projecting from the back of plate 42, and studs 49, 50 screwed into the wall of the housing, When the star wheel 27 is at rest, ledge 45 will rest on the tips of teeth a and b, as shown in Figure 2, while when the star wheel has been rotated 36, tooth tip a will have moved out from under the ledge as shown in Figure 3 while tooth tip b in moving from its position as shown in Figure 2 i teeth during the time when neither pawl is engaged will have raised ledge 42 against the effort of the springs 49 and 50. The plate will then again come to rest on tooth tip b and tooth tip cwhich occupies the original position of tooth tip b. The force exerted by springs 49 and 50 is ample to prevent any displacement of the star wheel during the return movement of the pawls which might otherwise cause a reverse movement of the star wheel, and to prevent any jarring ont of position of the with the star wheel. 1

The counter operating mechanism of this invention may obviously be modified, in the case of a counter which is to be driven in one direction only, by omitting one arm of the yoke and its associated detent, the yoke however being preferably properly balanced by a weight equal to that of the omitted parts.

While in order to comply with the statute, the invention has been described in language more or less specic as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise a preferred form of putting the invention into etfect, and the invention is therefore clanned in any of its forms or modifications within the legitimate and valid scope of the appended claim.

What is claimed is:

in a counting device having a housing, a train of counting wheels mounted for rotation on a shaft fixedly supported in said housing, a star wheel xed to the digit wheel of the train and an actuating member mounted in said housing; operating means activated by said actuating member to rotate said counting wheels, comprising: a yoke pivoted in said housing and oscillated by the actuating member; pawl means pivoted on said yoke and adapted to be engaged with an individual tooth of the star wheel at each oscillation of the yoke; rounded heads on said pawl means affording a rolling contact with the surface of the tooth of the star wheel engaged by a pawl in an operative movement thereof; means on said yoke limiting the pivotal movement of said pawl means in one direction relative to the yoke and also functioning to limit the amount of rotative movement of the star wheel at each oscillation of the yoke; and resilient means holding the pawl means in rest position against the means limiting the pivotal movement thereof.

References Cited in the ile of this patent UNITED STATES PATENTS 688,977 Skirrow Dec. 17, 1901 966,977 Zahn Aug. 9, 1910 1,179,956 Oliver Apr. 18, 1916 1,487,409 Wallin Mar. 18, 1924 1,939,822 Martin Dec. 19, 1933 2,426,715 Tatter Sept. 2, 1947 2,673,685 Hoffmann Mar. 30, 1954 FOREIGN PATENTS 158,445 Australia Aug. 25, 1954