AU604267B2 - Drum-type counting mechanisms - Google Patents

Description

COMMONWEALTH OF. AUSTPIALIA Form 10 Regulation 13 2) PATENTS ACT, 1952 COMPLETE SPECIFICATION (ORIGINAL) S' FOR IOFFICE USE6 0"2 67 Short Title: Int. Cl: Application Nurmber- Lodged: 4 94 Complete Specification-Lodged- S Accepted: Lapsed: 4 Published: Priority: r b I 1L^.

j r I i 7 Related Art: ~1 TO BE COMPLETED BY APPLICPAT Name of Applicant: LGZ LANDIS GYR ZUG AG Address of Applicant: CH-6301 ZUG, SWITZERLAND Actual Inventor: BURGI ERNST Address for Service: ARTHUR S. CAVE CO., Patent and Trade Mark Attorneys, 1 Alfred Street, Sydney, New South Wales, Australia, 2000.

Complete Specification for the invention entitled: DRUM-TYPE COUNTING MECHANISMS The follow-;ing statement is a full description of this invention, including the best method of performing it knownvm to me:- ASC-49 2 DRUM-TYPE COUNTING MECHANISMS This invention relates to drum-type counting mechanisms, and in particular to such mechanisms which include number drums arranged on shafts.

Drum-type counting mechanisms are used for counting quantities, for example in electricity meters, water meters, or heat meters, but can also be used in distance recorders or the like.

Such drum-type counting mechanisms comprise number drums which are mounted on a shaft and which carry the digits 0 to 9, and switching rollers which are generally arranged on a shaft parallel c thereto and which, together with the number drums, provide for decimal transfer between adjacent number drums. The counting result is Cott represented by a combination of one digit on each number drum, which 15 appears on the number drums at a read-out line which is generally covered by a screen. The number drums have resetting devices which C, uncouple the number drums from the switching rollers and which either always return the drum-type counting mechanism to zero, for which purpose for example a heart-shaped cam may be used, or with which it i 20 is possible to set any desired combination of numbers, including pure C tzeros, in particular by hand. Energy metering predominantly involves using meters with a setting arrangement of the latter kind.

For the purposes of decimal transfer, an entrainment means on Z Ithe number drum of the lower place or digit entrains teeth of the Ii 25 associated switching roller, after each full revolution of the number drum, and the switching roller transmits the movement to the number Idrum of the higher place or digit, the switching roller being constantly in engagement by means of teeth with the ring gear on the number drum. In that situation, the number drum at the higher place or digit is rotated on by precisely one digit. To provide for that movement,at least two teeth are required on the switching roller and thus also the ring gear of the number drum at the higher place or digit.

The previously-known drum-type counting mechanisms suffer from two weak points, and substantial technical means have to be used in order to eliminate these problems, as follows: in the resetting operation or when setting a new combination of *P 0 0000 0000 0000 00 0 0 0000 00 0 0 00 3 numbers, the digits can be displaced by fractions of a spacing between digits so that, when reading out the counting mechanism, the position of the digits relative to the read-out line is not adequately defined; and in the decimal transfer of a plurality of places or digits, the play involved in the gears gives rise to the combination of numbers being arranged in a row in a stepped configuration, which can make it difficult to read out the result.

A series of constructions are known, which seek to reduce those disadvantages. Swiss Patent Specification No. 585 936 describes a drum-type counting mechanism in which the eight-tooth switching rollers have two square projections in both axial directions. Leaf springs lie thereon, and seek to retain the switching rollers in one of four positions. In a decimal transfer operation, this arrangement 15 reduces play and the stepped or displaced configuration of the readout digits is reduced, The arrangement is further suitable to prevent displacement of a digit by a fraction of the spacing between digits when resetting the mechanism or when setting a new combination of numbers. However, such apparatus requires a larger amount of torque, 20 more components and a greater structural width than the previous drumtype counting mechanisms.

German Patent Application Publication No. 34 07 457 discloses another drum-type counting mechanism in which the switching rollers are carried on a shaft which is fixed to two resilient elements in 25 such a way that its spacing from the shaft of the number drums can be increased. The switching rollers each carry four short and four long teeth. In the operating condition, the teeth of the switching roller are held in engagement with the ring gear of the number drum by a slide member. In the resetting oper-ation or when setting a new combination of numbers, the engagement is released, and the switching roller goes to an abutment with an opening for the long tooth which is in opposite relationship to the long tooth which had been in a condition of engagement. The switching roller is therefore retained in the same angular position. When the new combination of numbers is selected at the number drums, the long tooth is displaced to engage into the corresponding gap between the teeth of the number drum. This arrangement does not prevent the occurrence of the stepped 00 0 ar Or 0

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Irce Io i 0r~ C I I .0373k/SC configuration in a multiple decimal transfer operation. It requires considerably more (and more complicated) components that previous drum-type counting mechanisms.

According to the present invention there is provided a drum-type counting mechanism, comprising: a set of number drums arranged on a drum shaft and each bearing a series of digits spaced around the respective drum, so that an aligned set of digits, one on each drum, can S represent a multi-digit number; oo o a series of switching rollers arranged on a roller shaft coo, S parallel to the drum shaft and each associated with a e*o0 respective adjacent pair of the number drums in which a first one of the pair provides a digit in the represented number of lesser significance than the second one of the pair; each switching roller having a first series of teeth *084 "o which engage with an entrainment means of the respective first oao number drum intermittently once per revolution of that first Snumber drum to advance the switching roller a predetermined amount; iVt each switching roller also having a second series of Sinvolute teeth with two alternating tooth forms which constantly mesh with a series of involute teeth of the I respective second number drum with two alternating tooth i pitches, so that the teeth having one of said tooth forms can mesh in only one of the different pitches and so that advance of the switching roller through said predetermined amount advances the respective second number drum by one digit spacing; 4 .0373k/SC the entrainment means of each number drum being disposed relative to the digits of that number drum to compensate for the average play between the number drums and the switching rollers, such that, upon simultaneous advance of more than one of the number drums, the digits of the advancing drums remain generally aligned; and means being provided to disengage the switching rollers from the number drums to permit setting of the number represented by the number drums.

A preferred embodiment of the invention, to be described in o: greater detail hereinafter, provides a drum-type counting *oo mechanism which, upon resetting or when setting a new ca .oo'6 combination of numbers, reliably prevents displacement of the digits by fractions of a spacing between the digits and, in multiple decimal transfer operations in one direction, also I rsr reliably prevents the digits from forming a row in a step j configuration, while requiring no more components than in S" previous drum-type counting mechanisms.

This may be achieved by the following preferred design C r4 i 4a Cs" criteria: all engaging teeth of the drum-type counting mechanism are of an involute configuration; both higher-place number drums and also switching rollers alternately have teeth with two different pitches which are of a specific configuration for their purpose and which in particular permit jerk-free performance of the decimal transfer operation; and an entrainment means has a lead by the magnitude of the average clearance in the decimal transfer operation relative to the digit position on the number drum.

The invention will now be described by way of example with 0 reference to the accompanying drawings, throughout which like parts 0000 os are referred to by like references, and in which: Figure 1 is a front view of a drum-type counting mechanism 00 0 oooo 0 15 according to an embodiment of the invention; o o ~Figures 2a and 2b show a number drum of the mechanism shown in O° 0Figure 1; Figures 3a and 3b show a switching roller of the mechanism shown in Figure 1; 00 0o00 20 Figures 4a to 4d show the manner of engagement of a lower-place "o number drum into a switching roller in the mechanism of Figure 1; and Figures 5a and 5b show the operating procedure involved in decimal transfer between a switching roller and a higher-place number .oo drum.

0 0 Figure 1 shows a drum-type counting mechanism which does not Sdiffer in that view from previous such mechanisms. It comprises a housing 1 in which a number drum shaft 2 is fixed at two points, with number drums 3 rotatably mounted thereon. A switching roller shaft 4 is also mounted at two points of the housing 1, parallel to the number drum shaft 2, with switching rollers 5 being rotatably arranged on the shaft 4. The switching rollers 5 have teeth which all have the same pitch but which are alternately of two different configurations. The lowest-place number drum 3' is driven by a stepping mechanism (not shown) by way of a ring gear 6 of narrow pitch. Decimal transfer occurs when the entrainment means 7 of a lower-place number drum 3 has performed a full revolution and entrains the associated switching roller 5 through a rotary angle corresponding to a number step, whereupon the switching roller in turn advances the higher-place number drum 3 by a number step. For that purpose all higher-place number drums 3 have a ring gear 8 into which teeth on the associated switching roller 5 permanently engage. The number drum 3 may carry a running or operating strip which includes the entrainment means 7 and which prevents the digits disposed on the number drums 3 from being damaged as a result of abrasion by the switching rollers 5. The running or operating strip may alternatively be omitted so that structural width is saved, with the same digit size, of the drum-type counting mechanism. In order to permit resetting or the setting of a new combination of numbers on the drum-type counting mechanism, it is necessary to remove the tooth engagement as between the switching rollers 5 and the number drums 3, which can be effected for example by means of parallel displacement of the number drum shaft 2 or the cot, C15 switching roller shaft 4 or however by other means.

Figure 2 shows a number drum 3, more particularly viewed in Figure 2a from the number drum 3 at the next lower place and in Figure 2b *11 '4

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7 fran the numrber drm 3 at the next higher place. Figure 2a shows the ring gear 8 which provides for the decimal transfer operation. It has number drm teeth 10 of the same tooth width, which are alternately of a large pitch 11 and a small pitch 12. The large pitch 11 has a deep tooth bottom 13 and the snail pitch 12 has a shallow tooth tottan 14, ,that is to say the tooth bottom 14 is higher than the tooth bottom 13. The teeth are of an involute tooth configuration. The ring gear 8 on the number drum 3 has twenty teeth when it carries ten digits.

The side of the number drum 3 which initiates the decimral transfer operation is shown in Figure 2b. It carries the entrainment means 7 for the decimal transfer operation, consisting of two pins 15 and which project towards the higher-place number drumn 3 beyond1 the edge of the number drun 3 being considered. Disposed between them is a radially extending half-round recess 16 in the edge 17 of the numiber drumi. The entrainment means 7 is displaced in such a way as to lead sea*the digits on the number drum 3 so that it initiates the decimal transfer sanewhat too early.

Figure 3 shows the switching roller 5, mrore particularly being a view from the side of the lower-place nunber dran 3 in Figure 3a and a view ai to the face of the roller in Figure 3b. The switching roller 5 has eight teeth, being alternately wide switching roller 4 teeth 18 and narrow switching roller teeth 19. Beginning fron the side of the numirber drum 3 at the higher place, the wide switch-ing roller teeth 18 first have a wide engagement tooth 20 which can engage into t C the deep tooth bottan 13 of the ring gear 8 of the number drun 3, I a Cthen a flat-topped, somewhat lower projection 21 which runs in the space between the two number drumns 3 cainected by the switching rollers and which cones into engagenvent with a pin 15 of the entraiment 30 means 7 only in the decimal transfer operation. The narrow switch-ing roller teeth 19 comprise, in the same sequence, firstly a narrow engagement tooth 22 whose tooth height is somewhat less than that of the 0 wide engagement tooth 20, and which engagesinto the tooth bottom 14 8 of the ring gear 8 of the higher-place nu~mber drum 3. That is then followed, over the remaining width of the switching roller 5, by a scaiewhat lower tooth portion 23 which can engage both into the space between the two pins 15 and 15' and also into the senicircalar recess 16 at the entrainabent means of the lower-place number drum 3. Each pair consisting of a narrow switching roller tooth 19 and a wide switching roller tooth 18 corresponds in its width to the spacing btween the digits on the number drum 3. The engagmnt teeth 20 and 22 are of an involute tooth configuration.

The mo~de of operation involved in the decinal transfer operation is set forth with reference to Figure 4 showing transfer from the number drum 3 at the lower place, to the switching roller 5. In Figure 4a, the first pin 15 of the entrainment means 7 on the number drum 3 has just reached the projection 21 on the switching roller after a full revolution, and begins to entrain the switching 00 0 00"'Mroller 5 in a rotary mo~vement. In Figure 4b that rotary movement has 0000advanced to such an extent that the tooth or-tion 23 of the narrow 0000 switching roller tooth 19 has now engaged into the space betweer, the 00 0 20 two pins 15 and 15' and into the semicircular recess 16 of the entrainment 00 0 000 means. The location at which the tooth portion 23 of the nrrocw "0000 switching roller tooth 19 is engae by the second pin 15' and takes 0 00 0 over the continuation of the movemant is illustrated in Figure 4c.

The change in load fran the conditioni of drive by the projection 21 to the caridition of drive by the tooth portion 22 of the narrow switching roller tooth 19 takes place continuously as the projection 0 21 is no longer driven by the pin 15 precisely at the rmrnent at which 0 G.

the tooth portion 23 of the narrow switching roller tooth 19 mroves 0 into the drive area of the pin 15'. The change in load accordingly age takes place in a jerk-free manner. Figure 4d shows the situation just prior to the end of the mrovement of the switching roller 5. In that position, shortly thereafter the second pin 15' will slide through under 04 Ct zt C rt£~ 9 the tooth portion 23 of the narrow switching roller tooth 19 and the next projection 21' on the switching roller 5 will remain in a position in which, after the next full revolution, it can again initiate the corresponding sequence of mo~vements. That entire series of movements takes place over a rotary angle which corresponds to a tooth pitch on the numnber roller 3. It is not possible for the narrow switching roller tooth 19 and the projection 21 each to perform the funiction of the other as only the narrow switching roller tooth 19 can engage into the number drum 3 at the location with the semicircular recess 16.

Figure 5 shows the co-operation of the switching roller 3 with the ring gear 8 of the number drxn 3 at the higher place. As shown in Figure it is only possible for a respective wide switching roller tooth 18 to engage into the deep tooth bottom 13, or a narrow switching 15 roller tooth 19 to engage into a shallow tooth bottomn 14. No other position is possible, as can be seen from Figure 5b, as when the narrow switching roller tooth 19 engages into the deep tooth bottom, that would result in overlapping between the teeth of the ring gear 8 the teeth of the switching roller, as indicated at 24 in Figure 5 by hatching of the mutually overlapping locations.

It is also easy to see that it is not possible for a wide switching roller tooth 18 to be introduced into a shallow tooth bottom 14 to such a depth as corresponds to the fixed spacing of the nu~mber drm '1 25 shaf t 2 from the switching roller shaft 4. If the number drum 3 is uncoupled from the switching roller 5 and is recoupled again after the combination of digits has been set, it is thus not possible for the number drum 3 to be displaced by fractions of the sequence of digits on Jj the number drum 3. The arrangmnt therefore reliably prevents displacement of the numxrber drms 3 by fractions of the sequence of digits.

The occurrence of a stepped configuration in a decimael transfer operation is a consequence of the play bteen the pins and teeth on the numxber drums 3 and the switching rollers 5. As stated, the entrainment means 7 have a displacement relative to the digits disposed on the number drums 3, that displacement being in leading relationship at the magnitude of the average play in the decimal transfer operation. That causes the decimal transfer to be initiated early and thus reduces the stepped configuration. The engaging teeth of the number drums 3 and the switching rollers 5 are of an involute tooth configuration, which gives better running properties and which, with equal tolerances, reduces the play between the trailing number drumns 3 and the switching rollers 5. That also reduces the stepped configuration in the decimal transfer operatic--. On all teeth, the necks thereof are disposed radially with respect to the respective roller or drumi, insofar as they can be contacted by another part of the drum-type counting mechanism during sequence of operating mo~vements, so that in that situation it is not possible for radial forces to be transmitted. In the decimal transfer operation, that provides for a jerk-free transition in drive fram the projection 21 to the tooth portion 23 of the narrow switching roller tooth 19 by the entrairnent means 7, which also reduces the occurrence of the stepped contfiguration. However all that does not apply it:: if the direction of rotation of the drum-type counting mechanism is L reversed. After a reversal in the direction of rotation, a stepped configuration occurs in the above-described drun-type countirxg mechanism, the multiple decimal transfer phase. Hoever that is not a material consideration in regard to mo~st d-tn-type counting mechanisms which are used in energy meters as they always retain the same direction of rotation.

In the case of the described drum-type counting mechanism, Ywever, the stepped configuration after reversal of the dirsecon of rotation is no greater than in the case of drum-type counting mechanisms in accordance with the state of the art.

In the described drum-type counting mechanism, the digits cannot be displaced by fractionis of the spacing between the digits, when resetting the mechanism or when setting a new combination of numnbers.

No stepping in the row of digits occurs in multiple decimal transfer operations in the usual direction of rotation and the stepping is no greater than in known drum-type counting mechanisms, after the direction of rotation of the drtin-type counting mechanism has been reversed.

In that connection, no additional components are required; the comp~onents are only of a different conifigurationi. The drirn-type counting mechanism therefore only conprises a housing 1, the number drumns 3, the switching rollers 5, the associated shafts and a device for decoupling the switching roll ers 5 fron the numnber druns 3. It can be constructed in a very simple manner and, as sanme of the individual components h thereof can be produced with greater tolerances and in a simpler fashion, it involves lower levels of manufacturing costs than known drum-type counting mechanisms.

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Claims (9)

1. A drum-type counting mechanism, comprising: a series of number drums arranged on a drum shaft and each bearing a series of digits spaced around the respective drum, so that an aligned set of digits, one on each drum, can represent a multi-digit number; o o a series of switching rollers arranged on a roller shaft parallel to o..,,the drum shaft and each associated with a respective adjacent pair of the number drums in which a first one of the pair provides a digit in the o o oo o repczsented number of lesser significance than the second one of the pair; °each switching roller having a first series of teeth which engage o0o0 with an entrainment means of the respective first number drum intermittently once per revolution of that first number drum to advance the switciing roller a predetermined amount; each switching roller also having a second series of involute teeth rrr with two alternating tooth forms which constantly mesh with a series of *4tt involute teeth of the respective second number drum with two alternating tooth pitches, so that the teeth having one of said tooth forms can mesh -I tr tr t in only one of the different pitches and so that advance of the switching roller through said predetermined amount advances the respective second number drum by one digit spacing; C the entrainment means of each number drum being disposed .c relative to the digits of that number drum to compensate for the average play between the number drums and the switching rollers, such that, upon simultaneous advance of more than one of the number drums, the digits of the advancing drums remain generally aligned; and means being provided to disengage the switching rollers from the number drums to permit setting of the number represented by the number drums.

2. A mechanism according to claim 1, wherein the two alternating tooth pitches of the number drums comprise a first pitch forming a deep ntooth bottom and a second pitch forming a shallow tooth bottom. T O 251367/MM 13

3. A mechanism according to claim 1 or 2, wherein the two alternating tooth forms on the switching rollers comprise a wide tooth form which can mesh only in one of the tooth pitches of the respective number drum and a narrower tooth form which can mesh in the other tooth pitch.

4. A mechanism according to claim 3, wherein each switching roller has, in line with each of the wide switching roller teeth, a respective ,lprojection which projects to a lesser extent than the switching roller" tooth and which has a blunt tip which can fit between the respective :adjacent number drums.

5. A mechanism according to claim 4, wherein the first series of teeth and the projections of the switching rollers have neck portions with radially extending sides.

6. A mechanism according to claim 4 or 5, wherein during advance of each switching roller, the roller has one of its projections and then one of i the teeth of its first series entrained by pins of the entrainment means of i the respective first number drum, to such an extent that the next i projection takes the initial position of said one projection. j 7. A mechanism according to claim 6, wherein the transition from S" entrainment of the projection to entrainment of the tooth of the first series by the entrainment means takes place in a jerk-free manner.

8. A mechanism according to any one of the preceding claims, S.wherein, during advance of each switching roller, a tooth of the first series of teeth engages in a recess in an edge of the respective first number drum.

9. A mechanism according to any one of the preceding claims, wherein the teeth of the second series having said one tooth form are prevented from meshing in the other of the pitches of the teeth of the respective number drum by virtue of the width of said one tooth form. ~II_ __Ii i 251367/MM A mechanism according to any one of the preceding claims, wherein the number drums do not have any running strips.

11. A drum-type counting mechanism substantially as herein described with reference to the accompanying drawings. DATED this 14th day of August, 1990. LGZ LANDIS GYR ZUG:'AG. By Its Patent Attorneys ARTHUR S. CAVE CO. 1 ii( 0006 0 00 000 0 04 0000 O 0000 0 0 II c:I Ft i'' \j c