US3636394A - Elastic contacts for carbon collector rings having insulating bodies in electric motors - Google Patents

Abstract

Contacts for carbon collector ring assemblies in electric motors, having a centrally disposed insulating boss and a plurality of contact laminae or flags, inserted between the insulating bodies of the assemblies and the boss, corresponding in their number to that of the collector rings, the laminae being inserted under pressure within the rings and having specially shaped portions both to adapt to the curvature on the inside surface of the rings and to the insulating pieces in the assembly.

Description

United States Patent Forste et al. I

[451 Jan. 18,1972

[54] ELASTIC CONTACTS FOR CARBON COLLECTOR RINGS HAVING INSULATING BODIES IN ELECTRIC MOTORS [72] lnventors: Walter Forste, Suhl, Thuringia; Joachim, Schreiber, Leipzig; Hans Stark, Suhl,

Thuringia, all of Germany [73] Assignee: VEB Elektrogeratewerk Suhl, Suhl,

v Thun'ngia, Germany [221 7 Filed: May 18, 1970 [2]] App]. No.: 38,438

[52] U.S.Cl. .....3l0/232 [51] lnt.Cl. ..1102k 13/02 [58] Field of Search ..310/232, 231, 235, 234, 233

[56] References'Clted UNITED STATES PATENTS 2,322,011 6/1943 French ..310/232 Chervenka ..3 10/232 Pandapas et al.. ....310/232 Ferris ....310/232 Primary Examiner-William M. Shoop, Jr. Assistant Examiner-B. A. Reynolds Attorney-Tab T. Thein [57] ABSTRACT Contacts for carbon collector ring assemblies in electric motors, having a centrally disposed insulating boss and a plurality of contact laminae or flags, inserted between the insulating bodies of the assemblies and the boss, corresponding in their number to that of the collector rings, the laminae being inserted under pressure within the rings and having specially shaped portions both to adapt to the curvature on the inside surface of the rings and to the insulating pieces in the assembly.

12 Claims, 20 Drawing Figures PATENTEnJmemz I 31636394 SHEET 1 0F 3 FIG. 2

INVENTORS WALTER FORSTE J'OACHIM SCHREIBER BY 2 HAN STARK AGENT Pmmmmmz 3.636.394

SHEET 2 (If 3 FIG. e i FIG? FIG. I20 I2 no 3 la I I3 I FIG. 12c

u V L INVE TORS 22- m. WALTER F RSTE T ,lmlh, JOACHIM SCHREIBER BY HA3? STARK Z A AGENT PATENTEU JAM 8I872 31535394 SHEET 3 BF 3 FIG 13 FIG. 15

l3 i2 I a FIG. 14 Q lb j Ma INVENTORS WALTER FORSTE BY IJ'OACHIM SCHREIBER Z HANS STARK TGENT ELASTIC CONTACTS FOR CARBON COLLECTOR RINGS HAVING INSULATING BODIES IN ELECTRIC MOTORS The invention relates to elastic contacts or laminae for supplying current to carbon collector rings in electric motors, the rings having bodies of insulating material.

In order to obtain proper contact between the collector rings of motors and their current lead-ins, different proposals were made. Thus it is known for example to apply a solderable layer to the inner surfaces of carbon collector rings, and to solder a contact ring thereto, a conductor being in turn soldered, riveted or welded to the ring.

Carbon collector rings had also been disclosed which are disposed on a body of insulating material and which have, as a means for supplying current, a pretensioned contact ring inserted on the inside of the collector ring. This, mostly resiliently designed contact ring may be so constructed that it is in one piece with the connectors and that, for example, the contact ring is constructed as a bushing which grips the carbon collector rings from the inside with its tumed-over edges, or that the contact ring has a triangular cross section which engages a corresponding cutout in the collector ring.

Other possibilities to establish a contact are, for example, that the carbon collector ring is equipped with a thread and that the contact ring, which has likewise a thread, is screwed into the collector ring; that the contact ring has a collar and is pressed inside the collector ring; or that a corrugated contact ring is employed which, in order to achieve a still better contact, is additionally soldered to the inner surface of the carbon collector ring which has been made adapted for soldering.

These known constructions have various drawbacks, such as:

In carbon collector rings which have a solderable layer on the inside to which smooth or corrugated contact rings are soldered, it is to be noted that after the soldering is done and the contact ring has subsequently cooled off, the latter gets detached from the soldering junction or that, in the most unfavorable of occurrences, the collector ring bursts.

In another disclosed contact, for example, the exact manufacturing tolerances of the inside diameter of the collector ring must be maintained by means of an elastic .con'tact ring which is designed as a bushing. The same applies to the insulating boss upon which the collector ring is pressed together with the inserted contact ring, as in the case of an overdimensioned insulating boss and an underdimensioned inside diameter of the collector ring, in which case either the lodgment of the carbon collector ring with the contact ring on the insulating boss is not possible or, when pressed thereon, the collector ring may break. To the inside diameter, in the most unfavorable instance, may yet have to be added the excess thickness of the material of the contact ring.

Similar conditions prevail in the case where the collector ring, to accommodate the contact ring, has a triangular cross section adapted to both parts. Equipping the two parts, contact and collector rings, with threads in order to join them is still costlier from a technical point of view, compared with the aforementioned designs, irrespective of the circumstance that manufacturing tolerances may exert such a strong effect that bursting of the collector ring may ensue. Additionally, the contact ring with a thread must have strong walls, and the differing expansion coefficients of carbon and metal may likewise produce destruction of the carbon collector ring.

Manufacturing contact rings with flanged collars likewise does not constitute a more advantageous union relative to the carbon collector ring inasmuch as the necessity of grinding the lateral surface and the inner beading of the contact ring relative to the receiving surface of the collector ring would be very expensive.

Production of collector ring bodies in one manufacturing operation, in which the collector rings are inserted together with the contact rings into a mold, requires very high molding pressures.

Multipartite compression molds must be employed for the purpose, and these make production expensive. Furthermore,

there is the danger that molding compound will become lodged between contact and carbon collector rings and an undesirable insulation is produced there, or that the contact rings with their connections are bent and torn off.

It is an object of the invention to eliminate the drawbacks as they exist in the prior art.

The invention has as its main object to provide elastic contacts for carbon collector rings, disposed on insulating bodies, with the establishment of a contact requiring but small technological outlays, to the effect that manufacturing may proceed with relatively wide production tolerances, that material requirements are small, the risk of breakage of the carbon collector rings during the assembly of the unit is eliminated, and that nevertheless perfect mechanical union between carbon collector rings and current lead-in lines is established which satisfies the electric requirements.

According to major features of the invention, the objects are accomplished in that preferably rigid metal contact laminae are inserted under pressure between the inside diameter of the carbon collector rings which are pretreated pyrolytically in a known manner, and an insulating boss which is part of the collector ring assembly and which is, corresponding to the required collector rings, provided with continuous recesses for the contact laminae, in such a way that the latter contact the collector rings with a bent, curved or arched surface which corresponds to that of the inside diameter of said collector rings.

The fixed connection between the collector rings, contact laminae and the insulating boss is established bymeans of elastic depressions or stamped deflections in the pressed-in parts of the contact laminae, opposite the contact surfaces of the inside diameters of the collector rings.

Also, the insulating boss, in accordance with the number of carbon collector rings being employed, may have noncontinuous recesses symmetrically distributed on its periphery for accommodating the contact laminae.

The insulating boss may likewise have noncontinuous and setoff recesses, corresponding to the number of collector rings being employed. The length of said recesses will be so dimensioned that with the laminae pressed in place, a pressure-type contact condition will be established.

The contact laminae may have offsets with lengths so dimensioned that they correspond to at least the width of a carbon collector ring.

The contact laminae may be constructed without or with right-angled terminal portions at their bends and on their top surfaces.

The depths of the continuousor the noncontinuous recesses in the insulating boss may be so dimensioned that between the second and the next following collector rings, in the lengthwise direction of the contact laminae, insulating pieces are unremovably inserted between carbon collector rings and contact laminae.

Furthermore the contact laminae, prior to being set into the collector rings, may have insulating layers applied to one side or both sides thereof at locations which must be additionally insulated during the assembly of the individual rings onto the insulating boss.

When insulating spacing disks are employed between the collector rings, these disks may be produced without any recesses for the passage of the contact laminae.

Additional grooves may be disposed, centered relative to the continuous or discontinuous recesses in the insulating boss, in conformity with the width of the depressions or stamped deflections of the contact laminae, and their depths are so dimensioned that a pressure-loaded contact condition is established between the carbon collector rings and the contact laminae.

Prior to their further use the contact laminae are preferably clean etched, and before being set between the rings and the boss they are immersed with their unattached ends in a gra- The complete collector ring assembly with inserted contact laminae is preferably subjected to insulation by means of an impregnating varnish or another insulating compound, lacquer or resin which sets after impregnation.

The outside diameters of the carbon collector rings in the finished assembly are preferably finished by grinding.

The technicoeconomical effects of the invention constitute a structurally simple solution of elastic contacts on carbon collector rings, mounted on an insulating boss, and where the entire ring assembly may be produced at relatively low cost and wherein nonetheless proper contact conditions are obtained which satisfy the requirements of electrical engineering.

Other objects and structural details of the invention will be apparent from the following description when read in conjunction with the accompanying drawings wherein FIG. 1 is an end view of a collector ring assembly incorporating the inventive contacts; I

FIG. 2 is a partly sectional view of the collector ring assembly, with contacts disposed according to the invention in the form of contact laminae having deflections therein, taken along line 2-2 of FIG. 1;

FIG. 3 is a sectional view of the assembly along line 33 of FIG. 2;

FIG. 4 is an end view of an insulating boss with discontinuous and setoff recesses, as used in FIGS. 1 to 3;

FIG. 5 is a side view of the boss of FIG. 4;

FIG. 6 is an end view of another insulating boss, with continuous recesses;

FIG. 7 is a side view of the boss of FIG. 6;

FIG. 8 is an end view of yet another insulating boss, with discontinuous recesses;

FIG. 9 is a side view of the boss of FIG. 8;

FIG. 10 is a fragmentary sectional view, similar to FIG. 2, showing a contact lamina with a depression, lodged between the carbon collector ring and the insulating boss;

FIG. 11 is a fragmentary cutoff view of an insulating boss having a groove disposed in its recess;

FIGS. 12a, 12b and 12c are respectively a side view, end view and top view of a contact lamina having a depression and a bent portion, as shown;

FIG. 13 is a side view of a contact lamina with a deflection, otherwise similar to that of FIG. 12a;

FIG. 14 is a side view of another contact lamina with a deflection and a right-angled terminal portion;

FIG. 15 is another fragmentary sectional view, similar to FIG. I0, showing a contact lamina inserted at the first collector ring of a three-part assembly, as was shown in FIG. 2, and taken along line l5-l5 ofFlG. 1;

FIG. 16 is yet another fragmentary sectional view, similar to FIGS. 10 and 15, showing a contact lamina inserted at the third collector ring of the exemplary three-part assembly, offset by 240 relative to the first collector ring of FIG. 15, and taken along line 16-16 of FIG. 1;

FIG. 17 is a side view of a contact lamina, similar to that of FIG. 1211, with insulating layers applied to both sides thereof; and

FIG. 18 is a side view of a contact lamina, similar to that of FIG. 13, with an insulating layer applied to one side only thereof.

Referring now to the drawings, a collector ring assembly is generally shown at 5 (see FIGS. 1 to 3), having running or contact surfaces 4, in a preferred, exemplary arrangement of the inventive contacts. The assembly includes, as a matter of example, three collector rings 2 which are mounted on an insulating boss 6 having inserted therebetween at least semirigid but elastic contact laminae l as well as insulating pieces 17. Modifications of the laminae will be described later with respect to the FIGS. 10, 12a, 12b, 12c, 13 and 14.

The contact laminae l are preferably rigidly constructed and consist of sheet-metal strips. At one end thereof is disposed, in one of the preferred embodiments of the laminae, a right-angled, offset terminal portion 13 (see also FIGS. l0, l5 and 16). In a modified lamina identified by numeral la, shown in FIGS. l2al2c and 17 there is an elastic depression 11, or alternatively there may be a stamped deflection 12, as shown for lamina I in FIGS. 2, 3, I3 and 14.

To assure a still better attachment of the contact lamina when it is mounted with the respective carbon collector ring 2 on the boss 6, an additional right-angled tenninal portion 14 may be provided, as shown in FIGS. l0, 14 (the latter for a lamina lb since it also has the deflection 12). A bent or arched portion 10 (as shown in FIGS. I to 3, l2a-l2c) is furthermore necessary to establish proper contacting, and the aforementioned bent portion is disposed at one end only, above the offset 13, and during the assembly of the collector ring unit 5, it will come to abut the inside diameter 3 of the rings 2 over the entire width thereof. The two bent portions must therefore be matched accordingly.

FIG. 3 shows recesses 7 for accommodating the laminae, which will be discussed somewhat later in more detail. FIG. 2 also shows insulating distance members or disks 20, similarly to be explained later.

The collector ring assembly 5 is assembled as follows: Onto the insulating boss 6 (or the modifications 6a, 6b to be referred to later), the carbon collector rings 2 are pushed in, with the contact laminae l lodged in the respective recesses, such as 7. FIGS. 4 and 5, 6 and 7 as well as 8 and 9 show different recesses, respectively identified by numerals 7, 7a and 7b, which are in the first instance discontinuous and setoff or stepped, in the second instance continuous, and in the third, discontinuous (with a single step). In FIGS. 1 to 3, the laminae are pushed in the discontinuous recesses 7 of the boss 6 while the depressions 11 or deflections I2 exert pressure against the setoff parts of the boss 6. The bent portion 10 rests against the curved inner surface 3 of the collector ring 2 so that proper contact conditions are established thereby.

Such contact conditions can further be improved in that the laminae l are immersed beforehand into a graphite emulsion and that, after the emulsion has dried, the graphite layer will adhere securely to the laminae. By this process (understandably equally well adapted for the modified laminae) the laminae may also be prefabricated and stored, and they will not oxidize, which would have an adverse effect on the electric contact resistance coefficient in the complete assembly.

For a more secure positioning when introducing the laminae I, la or lb together with the respective collector rings 2, onto the boss 6, 6a, 6b or 60, preferably the aforementioned deflection 14 is disposed and when the rings 2 are slid onto the boss, the respective lamina is automatically carried along. If the laminae do not have the right-angled portions or deflections, then they can be subsequently inserted, after the rings were placed on the boss, into the unoccupied slot between the recess of the boss 6 and the inner surface 3 of the rings 2.

In accordance with FIG. 11, a modified insulating boss 60 may likewise be designed so that it has disposed in its continuous recess 7c an additional, continuous groove 21 whose depth 23, relative to the depression 11 or deflection I2 of the inserted lamina, is so dimensioned that proper contact conditions are established. The width of groove 21 corresponds to the width 22 of depression II or deflection 12 of the respective laminae 1, la and/or lb.

FIG. I5 shows a lamina l with a depression 12 inserted into the first collector ring 2 of a three-part assembly. The offset 13 exerts pressure against the insulating boss 6. It should be noted that this structural arrangement might also be provided with the right-angled deflection 14, as shown in FIG. 10 or 14 (although omitted from FIG. 15 because it is made to correspond to a section of FIG. 1, where no such bent terminal portions have been shown, namely in FIG. 2).

In order to obtain perfect insulation relative to the first carbon collector ring, an insulating piece 17a (see FIG. 16), which is meshed up to depth 16a or 16b (see FIGS. 6 and 8) of the recesses 7a, 7b in the boss 6, is inserted above the contact lamina 1, up to its offset 13. The length of the insulating member 17a is so dimensioned that it terminates flush with the boss 6.

In the FIG. 16, three carbon collector rings 2 are shown, mounted on the boss 6, which are offset by 240 relative to the ring, as shown in FIG. 15.

The same would apply to the second ring (not shown by itself) wherein the contact lamina would be offset by 120 relative to the first ring.

The insulating members, as separate elements, could be omitted if the contact laminae themselves are provided beforehand with relatively rigid insulating layers as shown in FIGS. 17 and 18, for the respective laminae 1a and l.

Such insulation is applied in the form of two layers 18 on opposite sides of the lamina 1a, or of a single layer 19 applied on one side only of the lamina 1, as shown in these figures.

The free ends of the contact laminae 1, 1a, 1b may also be immersed in a graphite emulsion, as has been described above. in the preferred constructive embodiment additional insulation between the individual carbon collector rings 2 is unnecessary inasmuch as positioning of the rings on the boss is already secured through the elastic disposition of the contact laminae, and the exact spacing may also be obtained by means of special fixtures used during assembly.

However, as has been shown in FIGS. 1 and 3, the aforementioned spacing disks 20, made of insulating material, may be additionally employed. After a carbon collector ring 2 is mounted, a disk is placed between the adjoining rings. An additional groove for the passage of a contact lamina with an insulating piece 17 is not required.

So that no impregnating varnish or resin may penetrate into the interstices of rings 2 and cause some impediments in the operation of the electric motor, the rings 2 are first covered with a pyrolytic layer in a process which is known per se.

After assembly of the collector ring unit 5 is completed it is subjected to an insulation procedure, for example by means of an impregnating or insulating resin so that, after the latteris cured, secure holding together of all parts is achieved.

Owing to the presence of the pyrolytic layer of rings 2, the insulating layer will adhere to the rings so that, additionally, an increase in the length of the leakage path of the electric current will result. Subsequently, the bearing surfaces 4 of the assembly 5 are ground after the seating area in the inside bore of boss 6 has first been finished, and after the subsequent accommodation in the inside bore, and the pyrolytic layer, together with the impregnating varnish or resin, is then removed.

It will be understood by those skilled in the art that modifications are possible in the preferred exemplary embodiment described above, and that some of the individually described features can be combined to advantage, without affecting the scope of the present invention.

We claim:

. 1. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings,

wherein said laminae furthermore have stamped deflections opposite the contact surfaces inside said rings.

2. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, and wherein said recesses of the boss have stepped sections of different depths.

3. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid,

elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, and wherein said recesses of the boss have substantially centered grooves therein, with depths assuring a pressure-loaded contact condition with the respective laminae.

4. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss in serted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, wherein said laminae furthermore have elastic depressions opposite the contact surfaces inside said rings.

5. The contacts as defined in claim 2, wherein said boss has a number of recesses symmetrically disposed about its periphery, for accommodating said laminae, and corresponding in number of that of said rings.

6. The contacts as defined in claim 2, wherein said recesses of the boss are discontinuous with respect to its length.

7. The contacts as defined in claim 2, wherein said laminae have offset portions with a length corresponding to at least the width of the respective n'ngs.

8. The contacts as defined in claim 4, wherein said laminae have substantially right-angled bent terminal portions.

9. The contacts as defined in claim 4, further comprising insulating pieces substantially unremovably inserted between said rings and said laminae, the respective ones of said recesses of the boss having correspondingly dimensioned depths.

10. The contacts as defined in claim 4, further comprising at least one insulating layer applied to said laminae.

11. The contacts as defined in claim 4, further comprising insulating disks applied between said rings.

12. The contacts-as defined in claim 4, wherein said laminae have at least one portion clean etched, and a dry layer of a graphite emulsion applied to at least the unattached tenninal portions thereof.

- v UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION 1 mm; No. 5,656,594- Dated anuary 18, 1 2

lynventofls) Walter Forste et al.

It is certified that error appears in the above-identified patent "and that said Letters Patent are hereby corrected as shown below:

In column 6, eubolaims 5 6 and 7 should refer back to the claim P (and not to "2" as printed) Signed and sealed this 30th day. of May 1972.

(SEAL) Attest:

EDWARD I LFLETCHERJR. ROBERT GOTT-SCHALK Attesting Officer Commissioner of Patents 'oRM Po-105O (10-69) USCOMM-DC 603764359 7 U. 5. GOVERNMENT PRINTING OFFICE: IN! 0-366-334 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION v 5,656,594 Dated an y 1972 Patent No.

jnventoflS) Walter Forste et al,

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 6, eubclaims 5, 6 and 7 should refer back to the claim -I- (and not to "'2" as printed).

Signed and sealed this 30th day of May 1972.

(SEAL) Attest:

EDWARD I LFLETCHERJR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer USCOMM-DC 503764 69 17 U.S, GOVERNMENT PRINTING OFFICE: 1989 0-366-33 FORM PO-105O (10-69)

Claims (12)

1. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, wherein said laminae furthermore have stamped deflections opposite the contact surfaces inside said rings.

2. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, and wherein said recesses of the boss have stepped sections of different depths.

3. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, and wherein said recesses of the boss have substantially centered grooves therein, with depths assuring a pressure-loaded contact condition with the respective laminae.

4. Contacts for carbon collector rings disposed on insulating bodies in electric motors, comprising an insulating boss inserted within said insulating bodies, and at least semirigid, elastic metal contact laminae inserted between the latter and said boss, said laminae having a number corresponding to that of said rings, said boss being provided with recesses for at least partly lodging said laminae, the latter having bent portions which follow the curvature on the inside surface of said rings, wherein said laminae furthermore have elastic depressions opposite the contact surfaces inside said rings.

5. The contacts as defined in claim 2, wherein said boss has a number of recesses symmetrically disposed about its periphery, for accommodating said laminae, and corresponding in number of that of said rings.

6. The contacts as defined in claim 2, wherein said recesses of the boss are discontinuous with respect to its length.

7. The contacts as defined in claim 2, wherein said laminae have offset portions with a length corresponding to at least the width of the respective rings.

8. The contacts as defined in claim 4, wherein said laminae have substantially right-angled bent terminal portions.

9. The contacts as defined in claim 4, further comprising insulating pieces substantially unremovably inserted between said rings and said laminae, the respective ones of said recesses of the boss having correspondingly dimensioned depThs.

10. The contacts as defined in claim 4, further comprising at least one insulating layer applied to said laminae.

11. The contacts as defined in claim 4, further comprising insulating disks applied between said rings.

12. The contacts as defined in claim 4, wherein said laminae have at least one portion clean etched, and a dry layer of a graphite emulsion applied to at least the unattached terminal portions thereof.

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