US3646826A

US3646826A - Stepping device

Info

Publication number: US3646826A
Application number: US25944A
Authority: US
Inventors: Rolf Ake Sahlgren; B Ingvar Wiljanen
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1969-04-23
Filing date: 1970-04-06
Publication date: 1972-03-07
Anticipated expiration: 1989-03-07
Also published as: FR2039417A1; NO127423B; DE2018840B2; NL7005117A; DE2018840C3; SE333855B; FI50455B; BE749378A; FI50455C; DE2018840A1; DK126060B; GB1258861A; SU380034A3

Abstract

Stepping device for a comptometer provided with a ratchet wheel and a pawl. An oscillating or reciprocating movement of the pawl is changed to a unidirectional rotary movement of the ratchet wheel. The pawl is forked or bifurcated to form shanks on diametrical opposite sides of the ratchet wheel, which shanks are each provided with a projection cooperating with the teeth of the ratchet wheel. A least one of the shanks is provided with another projection situated at a circumferential distance from the projection on the same shank which is greater than the gear pitch of the ratchet wheel and so chosen that when the two projections of the said shank are in contact with the sides or flanks of two teeth of the ratchet wheel then the resultant force of the forces acting at these sides is directed through the rotary axis of the ratchet wheel.

Description

United States Patent Sahlgren et al. Mar. 7, 1972 [54] STEPPING DEVICE 390,494 10/1888 Loud ..74/577 [72] Inventors: lloli A]; SSEgremb'ZyLeMfxSB. :lngvar Wil- Primary Examiner wmiam R 0.1383

Janen an agen t 0 we en Assistant Examiner-Wesley S. Ratliff, Jr. [73] Assignee: Telefonaktiebolaget LM Ericsson, A!l0meyHane, & SPXecens Stockholm, Sweden [57] ABSTRACT [22] Filed: Apr. 6, 1970 Stepping device for a comptometer provided with a ratchet pp 25,944 wheel and a pawl. An oscillating or reciprocating movement of the pawl is changed to a unidirectional rotary movement of the ratchet wheel. The pawl is forked or bifurcated to form [30] Fme'gn Apphcamm Pnomy Dam shanks on diametrical opposite sides of the ratchet wheel, Apr. 23, 1969 Sweden ..5777/69 ich hanks are each provided with a projection cooperating with the teeth of the ratchet wheel. A least one of the shanks is [52] US. Cl ..74/ 142, 74/577 M Provided with another Projection Situated a! circumfefemial 511 Im. Cl. ..G05g 1/00 distance from the Projection the Same Shank which is 58 Field of Search ..74/142 128 575, 577 greater than the gear Pitch the ratchet wheel and chose that when the two projections of the said shank are in contact with the sides or flanks of two teeth of the ratchet wheel then [56] Reieremes cued the resultant force of the forces acting at these sides is UNITED STATES PATENTS directed through the rotary axis of the ratchet wheel.

48,927 7/ l 865 Giroud ..74/577 3 Claims, 4 Drawing Figures PaUZNWEIJM 7:912

INVENTORS Row A x: Smumm Bo Iuowm. wlumwu ATTORNEY STEPPING DEVICE The present invention relates to a stepping device for a comptometer provided with ratchet wheel and pawl, and more particularly to a comptometer in which an oscillating or reciprocating movement of the pawl is changed to a unidirectional rotary movement of the ratchet wheel.

With stepping devices of said type it is essential that the position of the ratchet wheel is well defined on completion of the stepping movement. It can occur when shaping the pawl in a conventional manner that the ratchet wheel springs back to its starting position or that the pawl becomes wedged in the ratchet wheel and prevents faultless stepping forward at the next signal. The problem exists especially with such comptometers where, owing to considerations of space, there is a relatively short oscillation arm for the pawl.

The purpose of the present invention is to eliminate said drawbacks and to achieve a stepping device at which wedging between the ratchet wheel and the pawl is prevented and the position of the ratchet wheel after a completed stepping is well defined.

The arrangement according to the invention is set forth in the appended claims.

The invention is described more in detail below by means of an embodiment with reference to the drawing in which:

FIG. 1 is a diagrammatic elevational view of a stepping device according to the invention in its rest position;

FIG. 2 is a fragmentary view of FIG. 1 in intermediate operational position upon energization of the magnet coil of the device;

FIG. 3 is a similar fragmentary view in a further advanced operational position; and

FIG. 4 is a similar fragmentary view in an operational position upon deenergization of the magnet coil.

In FIG. 1 a comptometer is shown, parts which have no direct connection with the invention, are only schematically indicated. A magnet coil 1 when energized causes attraction of an armature 2 with a projection 3 which interlocks with one end of a lever-formed pawl 4. The pawl is revolving around an axis of rotation 5 which according to the example is common to the drive gear 6 of the comptometer but may consist of a fulcrum pin. The other end of the pawl is bifurcated to form two shanks or forks 7 and 8 of which are situated on diametrically opposite sides of a ratchet wheel 9 which according to the example is arranged on the same axis 10 as the digit wheel 11 of the comptometer. The pawl need not necessarily be open at its end but may consist of a closed ring-shaped part, as is marked by broken lines, of and when construction points of views or 12 is qualities of the material make it advisable. A spring is fastened between a bracket 13 on the magnet coil and the pawl 4. The shanks of the pawl are each provided with two inwardly extending projections l4, l5 and l6, 17 respectively which are positioned to make engagement with the teeth of the ratchet wheel to turn the ratchet wheel. FIG. I shows the arrangement in its rest position. When the magnet works the pawl is turned upwards compared with the position shown in FIG. 1 due to the armature 2 being pulled downwards and pressing with its projection 3 the arm of the projection 16 on shank 8 downwards. FIG. 2 shows the position where the pawl during the upward movement of the pawl has come in contact with a tooth 20 of the ratchet wheel. During the continued reciprocating movement of the pawl the ratchet wheel is turned clockwise until another tooth 28 of the ratchet wheel counted counterclockwise is in contact with the projection 17 also on the shank 8 of the pawl. This position is indicated in FIG. 3. This figure also shows that the projections never fully occupy the spaces between adjacent teeth of the ratchet wheel. The ratchet wheel is retained in this position as long as the magnet attracts armature 2. The circumferential distance between the

projections

16 and 17 is chosen in such a manner, that the distance is larger than a gear pitch of the ratchet wheel in order to make possible that while the projection 16 bears against the opposite blank of the tooth 20 counted in the counterclockwise direction, the other projection 17 bears against the flank of the tooth 28 as the wheel 9 is turned in the clockwise direction of rotation. In this manner it is assured that when the projection 17 is engaged, the ratchet wheel stops in a well-defined position. Simultaneously the resultant of the forces which occur at the respective contact points of the ratchet wheel, is directed in such a manner, that it extends roughly through the axis of rotation 10 of the ratchet wheel. In this manner instability in the position of the ratchet wheel at the end of the movement of rotation is prevented as well as wedging between the pawl and the ratchet wheel. When the energization of the magnet ceases, the pawl 4 is brought back of the force of the spring 12 acting upon the pawl in counterclockwise direction. First the projection 15 comes in contact with the tooth 25 whereby the ratchet wheel 9 is turned in clockwise direction. This condition is shown in FIG. 4. The rotation can however only continue as long as the projection 14 has not come in contact with the tooth 22. In the same manner as at the shank 8 the distance and the mutual position between the projections are also here chosen in such a manner that the forces acting at the contact positions of the

projections

14 and 15 on the ratchet wheel produce a resulting force which is directed roughly through the axis of rotation 10 of the ratchet wheel. The last-mentioned condition appears from FIG. 1. In other words the stepping device has returned to its rest position. It is not necessary that both shanks 7 and 8 are provided with

stop projections

14 and 17 respectively. It may be enough to provide one a stop projection only on one shank; namely on the one which cooperates with the ratchet wheel during the energization of the magnet coil of the magnet. The danger for wedging or unintentional change of the position of the ratchet wheel is much larger at when the magnet coil is energized than when only the considerably smaller return force of the spring 12 acts upon the pawl.

We claim:

1. In an electromagnetic comptometer a stepping device for converting a linear reciprocating movement to a unidirectional rotary movement, said stepping device comprising:

a ratchet wheel;

' a common shaft seating said wheels for a joint rotation thereof;

an electromagnetic means selectively energizable;

a pivotally mounted two-armed pawl, one arm of said pawl constituting an armature arranged to be attracted by said electromagnetic means upon energization thereof thereby effecting a linear movement of said arm by pivoting the pawl, the other arm of the pawl being bifurcated thereby forming two shanks, said shanks being curved and positioned to encompass at least partly the outer peripheral outline of said ratchet wheel radially spaced apart therefrom, each of said shanks having thereon an inwardly protruding first projection engageable with valleys between the teeth of the wheel and one of said shanks having thereon a second inwardly protruding projection also engageable with valleys between the teeth of the wheel, the first and the second projection on said one shank being disposed at a circumferential spacing such that in response to successive attractions and releases of the armature said first projection engages the counterclockwise facing flank of successive teeth thereby causing incremental clockwise turning of the ratchet wheel and after turning of said wheel into a predetermined angular position said second projection engages the clockwise facing flank of a tooth thereby locking the ratchet wheel in said angular position when and while the armature is attracted, of said first and said second projection engaging said respective counterclockwise and clockwise facing flanks of said teeth of the ratchet wheel being also such that the forces simultaneously applied by said projections to the flanks of the respective two teeth extend approximately through the rotational axis of the ratchet wheel; and

a return spring means attached to the pawl and biased to pivot the pawl in counterclockwise direction, said pivotal movement of the pawl causing engagement of the projection on the other shank with the counterclockwise facing flank of a tooth upon deenergization of the electromagnetic means thereby turning the ratchet wheel in clockwise direction.

2. The stepping device according to claim 1 wherein a second projection is provided on said other shank also, said second projection being correlated with the first projection on the other shank so that both said projections on the other shank simultaneously engage oppositely facing flanks of teeth in a second predetermined angular position of the ratchet wheel thereby locking the wheel in said second angular position, the first and second projection on said other shank being so disposed that the forces simultaneously applied to the flanks of the respective two teeth also extend approximately through the rotational axis of the ratchet wheel.

3. The stepping device according to claim I wherein the peripheral outline of said projections on the shanks and of the valleys between the teeth of the ratchet wheel are so correlated that said protrusions engage valleys with play thereby preventing jamming of the projections in the valleys.

i 1K i

Claims

1. In an electromagnetic comptometer a stepping device for converting a linear reciprocating movement to a unidirectional rotary movement, said stepping device comprising: a ratchet wheel; a common shaft seating said wheels for a joint rotation thereof; an electromagnetic means selectively energizable; a pivotally mounted two-armed pawl, one arm of said pawl constituting an armature arranged to be attracted by said electromagnetic means upon energization thereof thereby effecting a linear movement of said arm by pivoting the pawl, the other arm of the pawl being bifurcated thereby forming two shanks, said shanks being curved and positioned to encompass at least partly the outer peripheral outline of said ratchet wheel radially spaced apart therefrom, each of said shanks having thereon an inwardly protruding first projection engageable with valleys between the teeth of the wheel and one of said shanks having thereon a second inwardly protruding projection also engageable with valleys between the teeth of the wheel, the first and the second projection on said one shank being disposed at a circumferential spacing such that in response to successive attractions and releases of the armature said first projection engages the counterclockwise facing flank of successive teeth thereby causing incremental clockwise turning of the ratchet wheel and after turning of said wheel into a predetermined angular position said second projection engages the clockwise facing flank of a tooth thereby locking the ratchet wheel in said angular position when and while the armature is attracted, of said first and said second projection engaging said respective counterclockwise and clockwise facing flanks of said teeth of the ratchet wheel being also such that the forces simultaneously applied by said projections to the flanks of the respective two teeth extend approximately through the rotational axis of the ratchet wheel; and a return spring means attached to the pawl and biased to pivot the pawl in counterclockwise direction, said pivotal movement of the pawl causing engagement of the projection on the other shank with the counterclockwise facing flank of a tooth upon deenergization of the electromagnetic means thereby turning the ratchet wheel in clockwise direction.

3. The stepping device according to claim 1 wherein the peripheral outline of said projections on the shanks and of the valleys between the teeth of the ratchet wheel are so correlated that said protrusions engage valleys with play thereby preventing jamming of the projections in the valleys.