US3578792A

US3578792A - Decade counter or the like

Info

Publication number: US3578792A
Application number: US826131A
Authority: US
Inventors: John J Affel
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1969-05-20
Filing date: 1969-05-20
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: GB1247458A; DE2019521A1

Abstract

The invention includes, for example, a number wheel and a gearwheel. Both wheels have a star-shaped ratchet around which a leaf spring fits. The spring holds the wheels together. The number wheel, thus, normally advances with the gearwheel. For reset, the number wheel may be turned relative to the gearwheel and the spring yields to allow such relative movement.

Description

United States Patent Inventor John J. Affel Canoga Park, Calif. Appl. No. 826,131 Filed May 20, 1969 Patented May 18, 1971 Assignee International Telephone and Telegraph Corporation DECADE COUNTER OR THE LIKE 9 Claims, 12 Drawing Figs. U.S. Cl. 235/ 144, 235/1 Int. Cl. G06c 15/42 Field ofSearch..... 235/144 (Misc.), 1457F856, iii (EMT 144 (Rake reset), 1.3, 139

References Cited UNITED STATES PATENTS 3/1921 Hussey 235/139 9/ l 944 Vroom 235/144 2/1953 Bliss 235/139 6/1964 Yolin 235/1 Primary ExaminerStephen J. Tomsky AttorneysC. Cornell Remsen, Jr., Walter J. Baum, Paul W. Hemminger, Percy P. Lantzy and Thomas E. Kristofiferson ABSTRACT: The invention includes, for example, a number wheel and a gearwheel. Both wheels have a star-shaped ratchet around which a leaf spring fits. The spring holds the wheels together. The number wheel, thus, normally advances with the gearwheel. For reset, the number wheel may be turned relative to the gearwheel and the spring yields to allow such relative movement.

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DECADE COUNTER OR THE LIKE BACKGROUND OF THE INVENTION This invention relates to decade counters or the like and, more particularly, to a number wheel, a gearwheel, and a detent for reset.

In the past, a decade counter number wheel has been held relative to a gearwheel by two tiny helical springs and detents. The number wheel has had internal notches around its periphery disposed between inwardly extending radial projec tions. The gearwheel then carries the detents which ride in between the projections.

The above-described prior art structures have several serious disadvantages. The projections cause the number wheel moment of inertia to be relatively high. This decreases maximum operating speed and causes excessive wear. The use of the detents and springs also requires a large number of component parts so small that they are difficult and expensive to assemble.

SUMMARY OF THE INVENTION In accordance with the device of the present invention, the above-described and other disadvantages of the prior art are overcome by providing a star-shaped ratchet fixed to a number wheel hub and an identical ratchet fixed to a gearwheel hub. A leaf spring then engages both ratchets. Utilizing the ratchets on the hubs, thus reduces the moment of inertia of each wheel. The wheels are, thus, capable of operating at high speeds without excessive wear. Further, the ratchets may be integral portions of the wheels. The wheels, for example, may be made of molded plastic. The single, large leaf spring reduces the number of component parts. Further, the lead spring is relatively large and is easy and inexpensive to assemble.

The above-described and other advantages of the invention will be better understood from the following description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings which are to be regarded as merely illustrative:

FIG. 1 is a front elevational view of a decade counter constructed in accordance with the present invention;

FIG. 2 is a sectional view of the counter taken on the line 22 shown in FIG. 1;

FIG. 3 is a rear elevational view of the counter;

FIGS. 4, 5, and 6 are sectional views illustratingthe Geneva movement in the counter;

FIG. 7 is a vertical sectional view through a number wheel and gearwheel;

FIG. 8 is an exploded perspective view of the number wheel and gearwheel;

FIG. 9 is a front elevational view of the number wheel;

FIG. 10 is a sectional view of the number wheel taken on the line 10-10 shown in FIG. 9;

FIG. 11 is a sectional view of the number wheel taken on the line 11-11 shown in FIG. 9; and

FIG. 12 is a rear elevational view of the number whee].

DESCRIPTION OF THE PREFERRED EMBODIMENT A decade counter 10 is indicated in FIG. 1, including a frame 11 through whicha shaft 12 is positioned. Shaft 12 is rotatable in frame 11. Number wheels 13 are rotatable about shaft 12. The same is true of gearwheels 14. The units number wheel is indicated at 13'. All of the gears 14 are driven by the same kind of mechanism. The mechanism may be entirely conventional, if desired. The mechanism driving units wheel 13' may also be entirely conventional. Number wheels 13 may be reset to zero by turning knob 15 which is fixed to shaft 12. The manner in which reset is accomplished is that each number wheel, such as number wheel 13 shown in FIG. 7, has a detent 16 which is biased by a spring 17 shown in FIG. 8 so that detent 16 is urged into an axial groove 18 in shaft 12 as shown in FIG. 2.

Units wheel 13 is advanced by a mechanism shown in FIG. 2, including pawl 19 and a ratchet 20. Pawl 19 is pivoted about shaft 21 fixed to frame 11. An armature 22 is fixed to pawl 19 and is attracted by solenoid 23.

Each number wheel carries two gear teeth, of 20, adjacent a gearwheel 14. It is by this mechanism that one complete revolution of one number wheel causes the next succeeding number wheel to advance one digit. The two gear teeth, of 20, drive the next succeeding gearwheel 14 through a pinion. Such pinions are indicated at 24 in FIG. 3. Pinions 24 are rotatably mounted on shaft 25 mounted on frame 11.

The Geneva teeth are indicated at 26 in FIGS. 4, 5, and 6. Alternate teeth of pinions 24 are shorter than the others. Thus, a pinion 24 turns only when the long tooth is allowed to mesh in between Geneva teeth 26. Otherwise, two of the long teeth rest on the outside surface of the number wheel. The number wheel is cut away at 27 as shown in FIG. 7 to allow the long tooth to enter between the Geneva teeth.

All of the structures of the decade counter 10 shown in FIG. 1 may be entirely conventional except for the component parts shown in FIG. 7. Number wheel 13 has a cylindrical portion 28 which carries numbers as indicated at 29 in FIG. 1. Number wheel 13 also has a hub portion 30 which has a starshaped ratchet 31. A web 32 connects hub 30 and portion 28. An apertured plastic disc 33 is sonic welded to boss 34 and to projections 35 molded integrally with number wheel 13. Disc 33 holds spring 17 and detent 16 inside boss 34.

Gearwheel 14 has teeth at 36 anda hub at 37. Hub 37 has a star-shaped ratchet identical to that of hub 30. Teeth 36 are connected to hub 37 by a web 38. C-shaped leaf spring 39 surrounds both ratchets of

hubs

30 and 37. Hub 37 has a projection 40 to cause the ratchets to be spaced apart a short distance. Number wheel 13 has a projection 41 which acts as a bearing for gearwheel 14. A projection 42 fits against shoulder 43 of gearwheel 14 to hold it in place. Projection 41 has a frustoconical surface 44 so that gear wheel 14 may be snap fit in the position shown in F IG. 7.

Number wheel 13 is again shown in FIG. 8. Ratchet 31 has not been sectioned for clarity. The ratchet of hub 37 is indicated at 37'. Number wheel 13 is originally molded with

projections

45 and 46 shown in FIGS. 10 and 11, respectively. These projections help to provide a firm bond of disc 33 to boss 34 and projections 35 when the number wheel is assembled by sonic welding.

As shown in FIG. 8, spring 39 has two

U-shaped end portions

47 and 48. Each of the

end portions

47 and 48 are positioned in between a different adjacent pair of the teeth of ratchet 31. For example, in- FIG. 12, spring end portion 47 is positioned between

ratchet teeth

49 and 50, and end portion 48 is positioned between

ratchet teeth

51 and 52.

When counter 10 is completely assembled, the spring 39 between each number wheel 13 and each gearwheel 14 is positioned around the respective gear ratchets 31 and 37" as indicated in FIG. 12. In this position, when the gearwheel is driven, the number wheel 13 is rotated with the gearwheel. This is true because the spring 39 holds the wheels together. The number wheel is advanced in a counterclockwise direction as shown in FIG. 9. Detent 16 will drop in groove 18 without stopping the number wheel 13 from rotating on shaft 12. On the other hand, should it be desirable to return the counter 10' to zero, knob 15 is turned in a counterclockwise direction as shown in FIG. 9, and groove 18 will pick up detent 16 and cause number wheel 13 to rotate. Because of 'the gearing, the corresponding gearwheel will not rotate. Spring 39 then deflects to allow the rotation of the number wheel 13 relative to the gearwheel 14.

Note will be taken that the ratchets 31 and 37' are close to the rotational axes of the wheels. The moment of inertia of each wheel is relatively low. This increases maximum operating speed and prevents excessive wear. The spring 39 is relatively large and easy to assemble. The prior art use of small detents and springs and other structures is thus avoided. The device of the present invention, therefore, is easy and inexpensive to assemble and requires only a few large component partswhich are easy to handle.

I claim:

1. In a decade counter or the like, the combination comprising: a first wheel; a second wheel; means mounting said wheels in relative positions such that they are fixed axially relative to each other but that they both are rotatable about a common axis, one of said wheels having a hub, said hub having a starshaped ratchet, said ratchet having teeth pointed radially outward away from said axis; and spring means biased against said ratchet in a position to hold said wheels yieldingly in fixed rotary positions relative to each other, said spring means being movable to allow rotation of one of said wheels relative to the other when a force is applied to the one and the other is held stationary, said other wheel having a hub with a star-shaped ratchet, the latter having a cross section perpendicular to said axis substantially identical to that of said one wheel.

2. The invention as defined in claim 1 wherein said mounting means includes an axial projection fixed to the center of one wheel, the other wheel having a hole through the hub thereof, said hole having a cylindrical internal surface concentric with said axis, said projection having an outer cylindrical surface concentric with said axis to fit contiguous to the hole surface rotatable thereagainst, said projection having an annular shoulder to fit on one side of said other wheel to hold said wheels together, the other side of said other wheel having an annular rib in contact with the hub of said one wheel, said shoulder having a frustoconical surface so that said other wheel may be snap fit into place around said projection between the hub and shoulder of said one wheel, said one wheel having a disc-shaped web fixed thereto at a position spaced axially from said other wheel, said other wheel also having a disc-shaped web at said other side thereof spaced from said one wheel web, said ratchet teeth of both wheels being located between said webs, said spring means including a C-shaped leaf spring surrounding the ratchet teeth on both of said wheels, said spring having a width approximately equal to the spacing between said webs, whereby said webs keep said spring in place, said spring having a uniform width and thickness throughout its length, said spring having two U- shaped end portions, each end portion being positioned in between a different adjacent pair of ratchet teeth, both pairs of teeth being disposed adjacent one another, said spring having a surface made by moving an axial line perpendicular to its length.

3. The invention as defined in claim 1, wherein said spring means is a C-shaped leaf spring surrounding the ratchet teeth on both of said wheels.

4. The invention as defined in claim 3, wherein said spring has two U-shaped end portions, each end portion being positioned in between a different adjacent pair of ratchet teeth.

5. The invention as defined in claim 4, wherein said mounting means includes an axial projection fixed to the center of one wheel, the other wheel having a hole through the hub thereof, said hole having a cylindrical internal surface concentric with said axis, said projection having an outer cylindrical surface concentric with said axis to fit contiguous to said hole surface rotatable thereagainst.

6. The invention as defined in claim 5, wherein said projection has an annular shoulder to fit on one side of said other wheel to hold said wheels together.

7. The invention as defined in claim 6, wherein said shoulder has a frustoconical surface so that said other wheel may be snap fit into place around said projection between the hub and shoulder of said one wheel.

8. The invention as defined in claim 4, wherein one of said wheels has a disc-shaped web fixed at a position spaced axially from the other wheel, said other wheel also having a discshaped web fixed at a position spaced axially from said one wheel, said ratchet teeth of both wheels being located between said webs, said spring havin a width approximately equal to the spacing between said we 5, whereby said webs keep said spring in place.

9. The invention as defined in claim 8, wherein said spring has a uniform width and thickness throughout its length.

Claims

1. In a decade counter or the like, the combination comprising: a first wheel; a second wheel; means mounting said wheels in relative positions such that they are fixed axially relative to each other but that they both are rotatable about a common axis, one of said wheels having a hub, said hub having a star-shaped ratchet, said ratchet having teeth pointed radially outward away from said axis; and spring means biased against said ratchet in a position to hold said wheels yieldingly in fixed rotary positions relative to each other, said spring means being movable to allow rotation of one of said wheels relative to the other when a force is applied to the one and the other is held stationary, said other wheel having a hub with a star-shaped ratchet, the latter having a cross section perpendicular to said axis substantially identical to that of said one wheel.

2. The invention as defined in claim 1 wherein said mounting means includes an axial projection fixed to the center of one wheel, the other wheel having a hole through the hub thereof, said hole having a cylindrical internal surface concentric with said axis, said projection having an outer cylindrical surface concentric with said axis to fit contiguous to the hole surface rotatable thereagainst, said projection having an annular shoulder to fit on one side of said other wheel to hold said wheels together, the other side of said other wheel having an annular rib in contact with the hub of said one wheel, said shoulder having a frustoconical surface so that said other wheel may be snap fit into place around said projection between the hub and shoulder of said one wheel, said one wheel having a disc-shaped web fixed thereto at a position spaced axially from said other wheel, said other wheel also having a disc-shaped web at said other side thereof spaced from said one wheel web, said ratchet teeth of both wheels being located between said webs, said spring means including a C-shaped leaf spring surrounding the ratchet teeth on both of said wheels, said spring having a width approximately equal to the spacing between said webs, whereby said webs keep said spring in place, said spring having a uniform width and thickness throughout its length, said spring having two U-shaped end portions, each end portion being positioned in between a different adjacent pair of ratchet teeth, both pairs of teeth being disposed adjacent one another, said spring having a surface made by moving an axial line perpendicular to its length.

8. The invention as defined in claim 4, wherein one of said wheels has a disc-shaped web fixed at a position spaced axially from the other wheel, said other wheel also having a disc-shaped web fixed at a position spaced axially from said one wheel, said ratchet teeth of both wheels being located between said webs, said spring having a width approximately equal to the spacing between said webs, whereby said webs keep said spring in place.