US3301986A

US3301986A - Electric current transfer structure including contact balls

Info

Publication number: US3301986A
Application number: US495475A
Authority: US
Inventors: Russell E Frink
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1965-10-13
Filing date: 1965-10-13
Publication date: 1967-01-31
Anticipated expiration: 1984-01-31
Also published as: GB1109329A

Description

R. E. FRINK Jan. 31, 1967 ELECTRIC CURRENT TRANSFER STRUCTURE INCLUDING CONTACT BALLS 2 Sheets-Sheet 1 Filed Oct. 13, 1965 k mm T W Q WE. W m sv SB u Du ATTORNEY WITNESSES Jan. 31, 1967 R. E. FRINK ELECTRIC CURRENT TRANSFER STRUCTURE INCLUDING CONTACT BALLS Filed Oct. 15, 1965 O P E RAT N G MECHANISM 2 Sheets-Sheet 2 F IG. 4

United States Patent Ofifrce 3,301,986 Patented Jan. 31, 1967 ELECTRIC CURRENT TRANSFER STRUCTURE INCLUDING CONTACT BALLS Russell E. Frinlr, Forest Hills, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 13, 1965, Ser. No. 495,475

17 Claims. (Cl. 200166) This invention relates to electrical apparatus and, more particularly, to means for transferring electrical current between relatively movable current carrying parts.

In certain types of electrical apparatus, such as circuit interrupters, it is necessary to transfer relatively large magnitudes of electrical current between relatively movable current carrying parts of the apparatus. For example, during a circuit interrupting operation of certain types of circuit interrupters or circuit breakers, it may be necessary to efficiently transfer thousands of amperes between relatively movable current carrying parts of the circuit interrupter. It has been found that structures provided in the past for this purpose are subject to certain limitations when called upon to perform repetitive operations. For example, an electrical contact which is designed to carry high momentary current is limited as to the maximum current that can be carried through each point of contact between relatively movable parts because of blowoff forces created by current converging to the point of contact. Considering each point of contact which carries continuous current between relatively movable, current carrying parts, the voltage drop at each point of contact is usually larger than the voltage drop through the balance of the parts.

Certain problems may also arise due to the mechanical failure of the structure such as a flexible conductor or the relatively large size of the structure required to transfer a relatively large magnitude of current. It is therefore desirable to provide an improved means for transferring relatively large magnitudes of current between relatively movable conducting parts in an electrical apparatus which is more compact in size and which overcomes certain other problems of structures of the same general type which have been employed in the past.

It is an object of this invention to provide a new and improved means for carrying electrical current between two relatively movable current carrying parts.

Another object of this invention is to provide a more compact structure for transferring relatively large electrical currents between relatively movable current carrying parts.

A further object of this invention is to provide a circuit interrupter including improved means for carrying electrical current between relatively movable, current carrying parts of the interrupter.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a front elevational view, partly in section, of a current joint or structure embodying the principal features of the invention;

FIG. 2 is a view in section of the current carrying apparatus shown in FIG. 1, taken along the line II-II with a portion of the apparatus broken away;

FIG. 3 is a diagrammatic view of a circuit interrupter including the current carrying apparatus shown in FIGS. 1 and 2; and

FIG. 4 is a diagrammatic view of another type of circuit interrupter including the current carrying apparatus shown in FIGS. land 2.

Referring now to the drawings and FIGS. 1 and 2 in particular, there is illustrated a current transfer means 10 which is adapted to transfer relatively large magnitudes of electrical current between relatively movable, current carrying parts or members. In general, the current transfer structure 10 comprises a first electrical conductor which, in this instance, includes the tubular conductor 30 and the associated conducting end ring 62 and a second electrical conductor which, in this instance, is an electrically conducting shaft or rod C1 which is disposed within or to pass through the first electrical conductor.

In order to provide a housing for a plurality of electrically conducting

balls

42 and 44, as will be explained hereinafter, at least a portion of the inner surface of the tubular conductor 30 as indicated at 30E is shaped or formed to provide an annular space or chamber between the tubular conductor 30 and the conducting shaft C1, as indicated at 65 in FIG. 1 In order to retain the conducting

balls

42 and 44 in the annular space 65 between the tubular conductor 30 and the conducting shaft C1 as well as for other purposes, the conducting ring 62 is disposed at the left end of the tubular conductor 30, as viewed in FIG. 1, to substantially close off the left end of the annular space or chamber 65 with the conducting shaft C1 also disposed within or passing through the conducting ring 62. It is to be noted that the balance of the inner surface of the tubular conductor 30 as indicated at 30G is slightly larger in size than the outer surface of the conducting shaft C1 and is of the same configuration as the cross-section of the conducting shaft C1 which, in this instance, is substantially circular. In order to retain the conducting ring 62 in assembled relationship with the tubular conductor 30, the internally threaded end cap 52 is disposed around and engages the externally threaded portion 30B provided at the left-end of the tubular conductor 30, as best shown in FIG. l.

In order to provide a pair of contact areas or surfaces on the inner surfaces of the conducting ring 62 and the tubular conductor 30 which are spaced along the longitudinal dimension of the conducting shaft C1, the inner surfaces of the conducting ring 62 and the tubular conductor 30 are oppositely beveled or chamfered at the opposite ends of the generally annular space 65 as indicated at 62A and 30F, respectively, preferably at an angle of substantially 45 with respect to the longitudinal axis of the conducting shaft C1.

Considering the tubular conductor 30 and the conducting ring 62, taken together as a first overall outer couductor, and the conducting shaft or rod C1 as a second conductor, it is important to note that at least one of the overall conductors is relatively movable with respect to the other overall conductor. More specifically, the conducting shaft or rod C1 may be rectilinearly or rotatably movable with respect to the first overall conductor which includes the tubular conductor 30 and the conducting ring 62; the first overall conductor may be rectilinearly or rotatably movable with respect to the conducting shaft C1, or both overall conductors may be rectilinearly or rotatably movable with respect to the other conductor. In order to provide a plurality of current carrying paths between the conducting shaft C1 and the first overall conductor just described during the movement of the shaft Cl with respect to the first overall conductor or during the movement of the first overall conductor with respect to the shaft C1, a plurality of pairs of electrically conducting

balls

42 and 44 are disposed in the annular space or chamber 65 between the tubular conductor 30 and the conducting ring 62 and the conducting shaft C1 around the periphery of the conducting shaft C1, as shown in FIG. 2. The

balls

42 and 44 which make up each pair of conducting balls are spaced from one another along the longitudinal dimension of the conducting shaft C1 adjacent to the

respective contact areas

62A and 30F on the conducting ring 62 and the tubular conductor 30, respectively.

In order to resiliently bias each pair of conducting

balls

42 and 44 into contact making engagement with the

contact areas

62A and 30F, respectively, and also with spaced points on the periphery of the conducting shaft C1, a plurality of separate biasing means 66 are disposed in the annular space 65 between the respective pairs of conducting

balls

42 and 44. Each biasing means 60 comprises a pair of spaced

spring seat members

64 and 66, each of the

spring seat members

64 and 66 including a curved or part-spherical surface which bears against one of the associated conducting

balls

42 or 44, respectively. A compression spring 68 is disposed between each pair of

spring seat members

64 and 66 with the ends of the spring 68 bearing against the shoulders provided on the respective

spring seat members

64 and 66 with a portion of each of the

spring seat members

64 and 66 projecting inside the biasing spring 68, as illustrated. The spring 68 applies oppositely directed biasing forces to the associated conducting

balls

42 and 44 to drive or push the

balls

42 and 44 into good contact making engagement with the

contact areas

62A and 30F respectively and into good contact making engagement with spaced points on the conducting shaft C1. Since a large number of current carrying paths may be provided in a relatively compact structure as disclosed, the contact pressure required on each of the conducting

balls

42 and 44 may be kept relatively low to thereby reduce the mechanical wear on the parts that might otherwise result.

In order to maintain the plurality of pairs of conducting

balls

42 and 44 in spaced relation around the periphery of the conducting shaft C1, the portion of the tubular conductor 30 as indicated at 30E between the

contact areas

62A and 30F may include a plurality of axially extending grooves or flutes, as indicated at 30H in FIG. 2, with each pair of conducting

balls

42 and 44 and the associated biasing means 60 being at least partially disposed in the associated groove on the inner surface of the portion 30E of the tubular conductor '30.

In order to retain an additional conducting member 22 in assembled relationship 'with the tubular conductor 30, the other end of the tubular conductor 30 as indicated at 30C may be externally threaded to receive a retaining nut 24 within the conducting member 22 being disposed between a shoulder 30A provided on the external surface of the tubular conductor 36 and the retaining nut 24 which may be tightened against the conducting member 22. The conducting member 22 will then be retained in assembled relationship with the outer tubular conductor 30 for movement therewith.

In the operation of the current transfer structure 10, each of the conducting

balls

42 and 44 forms a first point contact on the one hand with one of the

respective contact areas

62A or 30F on the conducting ring 62 or on the tubular conductor 30, respectively, and on the other hand forms a point contact with the conducting shaft or rod C1. These point contacts result from the biasing action of the biasing means 60 which drives the conducting

balls

42 and 44 at the opposite ends of each biasing means 60 into the wedge-shaped or tapered spaces which result at the ends of the annular space 65. In other words, a first set of current carrying paths is formed which extends from the tubular conductor 34), into the conducting ring 62, and then to the conducting shaft C1 through a plurality of paths spaced around the periphery of the shaft C1 through the conducting balls 42. At the opposite end of the annular space 65, a similar set of current carrying paths result which extends from the tubular conductor 30, through the spaced conducting balls 44 around the periphery of the shaft C1 and then into the conducting shaft C1. It has been found that during the operation of a current transfer structure which was constructed, when the conducting shaft C1 moves relative to the tubular conductor 30 and the conducting ring 62, either in a reciprocating manner or in a rotating fashion, the conducting

balls

42 and 44 remain substantially stationary with respect to the conducting shaft C1 since the frictional forces exerted on the

balls

42 and 44 by the conducting ring 62 and the tubular conductor 30, respectively, and by the

spring seat members

64 and 66, respectively, which tend to maintain the conducting

balls

42 and 44 in a relatively stationary position with respect to the shaft C1 are greater than the frictional forces exerted on the

balls

42 and 44 which might otherwise tend to cause the

balls

44 and 42 to rotate in place.

Referring now to FIG. 3, there is illustrated a circuit interrupter or circuit breaker CB which includes the current transfer structure 10 and which is adapted when closed to form a closed circuit between the line conductors L1 and L2, indicated diagrammatically. As illustrated, the circuit interrupter CB includes a relatively stationary contact means 120 which comprises a plurality of relatively stationary contact members 122 which are electrically connected to the line conductor L1. The relatively stationary contact means 120 is adapted to be engaged by a movable conducting member C1 which forms part of a current transfer structure 10, as previously described in detail. The free end .of the movable conducting member C1 may be curved as indicated at 128 to facilitate the entrance of the movable conducting member C1 into the stationary contact fingers 122 which may be resiliently mounted. The movable conducting member C1 is electrically connected to the other line conductor L2 through the conductor member 22, the tubular conductor 30 and the conducting ring 62 which forms part of the current transfer structure 10 and the conducting

balls

42 and 44 which form part of the current transfer structure 10, as previously described.

In order to actuate the movable conducting member C1 into and out of engagement with respect to the stationary contact means 120 to thereby open and close the electric circuit between the line conductors L1 and L2, the operating mechanism as indicated at is operatively connected to the movable conducting members C1 through an operative connection, as indicated diagrammatically at 112, and through an electrically insulating member, as indicated at 114 in FIG. 3. It is to be noted that in this circuit interrupter CB, the conducting shaft C1 is arranged for reciprocating or rectilinear movement with respect to the tubular conductor 30 and the conducting ring 62 which forms part of the current transfer structure 10 with the tubular conductor 30 and the conducting ring 62 being held in a relatively stationary position with respect to the conducting shaft C1.

Referring now to FIG. 4, there is allustrated a second circuit interrupter or disconnecting switch SW which includes the current transfer structure 10 and which is adapted when closed to complete an electric circuit which extends between the line conductors L1 and L2, indicated diagrammatically in FIG. 4. The disconnecting switch SW as illustrated includes a plurality of stationary contact members 222 which are electrically connected to the line conductor L2. The disconnecting switch SW also includes a movable conducting member or switch blade 22 which is mounted on the tubular conductor 30 which forms part of the current transfer structure 10, as previously described, for movement with the tubular conductor 30 when the switch blade 22 is actuated by a suitable operating mechanism (not shown). The other line conductor L1 is electrically connected to the switch blade 22 through a conducting shaft or rod C2 which is disposed within or to pass through the tubular conductor 30, through the plurality of conducting

balls

42 and 44 whioli are included as part of the current transfer structure 10 and through the conducting ring 62 and the tubular conductor 30 which make up part of the current transfer structure 10 to the switch blade 22. As illustrated in FIG. 4, the opposite ends of the conducting shaft C2 may be journaled in

suitable bearing supports

212 and 214 which are disposed around the conducting shaft C2 at the opposite ends of the shaft C2, as shown in FIG. 4.

In the operation of the disconnecting switch SW, the switch blade 22 which moves with the tubular conductor 30 .of the current transfer structure may be rotated into or out of engagement with the stationary contact members 222 to thereby open and close the electric circuit between the line conductors L1 and L2.

It is to be understood that in a current transfer structure as disclosed, a single set of conducting balls may be provided around the periphery of the conducting shaft C1 with the biasing means 60 bearing against a substantially flat surface on the conducting ring 62 rather than including an additional set of conducting balls which bear against a beveled inner surface on the conducting ring 62 as in the preferred embodiment. It is also to be understood that a separate means may be provided in the annular space 65 for maintaining the pairs of balls in spaced relation around the periphery of the conducting shaft C1. In other words, a ring shaped member having a plurality of axially extending grooves on its inner surface may be disposed between the

balls

42 and 44 and the inner surface of the tubular conductor 30 and may be formed from an electrically insulating material where desired since the conducting

balls

42 and 44 in a current transfer structure as disclosed carry current between the conducting shaft C1 and the conducting ring 62 and the tubular couductor 30 only through the beveled contact areas at the ends of the annular space 65. It is also to be understood that the conducting ring 62 may be formed integrally with the tubular conductor 30 to form an overall outer conductor since the purpose of providing a separate conducting ring 62 is to facilitate assembly of the conducting

balls

42 and 44 in the annular space 65 along with the separate biasing means 60 which are provided with each pair of conducting

balls

42 and 44. It is to be further understood that the

balls

42 and 44 may be hollow in a particular application or that a central core of electrical insulating material may be provided with a suitable layer of electrically conducting material on the outer surface of each of such balls.

Considering the circuit interrupters disclosed, it is to be understood that a separate contact means may be mounted on the movable conducting member provided or the contact means may be formed integrally with the movable conducting memben. I V

This apparatus embodying the teachings of this invention has several advantages. For example, a current transfer structure is disclosed which is extremely compact compared with current transfer structures of the same general type which have been employed in the past. It has been found that extremely large magnitudes of electric current may be transferred between relatively movable parts in an electrical apparatus in an extremely small space. Another advantage of the disclosedcurrent transfer structure is that the resilient biasing means provided for the

contact balls

42 and 44 compensates for or permits a limited misalignment between the relatively movable parts which are required in a particular application since a limited degree of misalignment between the relatively movable current carrying parts in electrical apparatus is compensated for by movement of the conducting balls into or out of the tapered or wedge shaped recesses provided at the opposite ends of the annular space in the disclosed current transfer structure. Since a relatively large number of current paths may be provided in vention may be made without departing from the spirit and scope thereof, it is intended that all of the matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In combination, a tubular electrical conductor having an inner surface, another electrical conductor disposed within the tubular conductor, at least one of the conductors being movable with respect to the other conductor, a portion of the inner surface of the tubular conductor shaped to provide a generally annular space between the conductors, at least one end of the portion beveled to provide a contact area on the inner surface of the tubular conductor, a plurality of electrically conducting balls disposed in the annular space around the periphery of said another conductor adjacent to the contact area on the inner surface of the tubular conductor, and separate means disposed in the annular space for biasing each ball into contact malking engagement with the contact area on the inner surface of the tubular contact and wtih said another conductor.

2. A combination as claimed in claim 1 wherein means is provided in the annular space for maintaining the plurality of balls in spaced relation around the periphery of said another conductor.

3. A combination as claimed in claim 1 wherein the inner surface of the tubular conductor is provided with a plurality of axially extending grooves in which the re spective balls are at least partially disposed for maintaining the balls in spaced relation around the periphery of said another conductor.

4. In combination, a tubular electrical conductor having an inner surface, another electrical conductor disposed within the tubular conductor, at least. one of the conductors being movable relative to the other conductor, a portion of the inner surface of the tubular conductor shaped to provide an annular space between the conductors, the ends of said portion oppositely beveled to provide a pair of spaced contact areas on the inner surface of the tubular conductor, a plurality of pairs of spaced, electrically conducting balls disposed in the annular space around the periphery of said another conductor adjacent to the respective contact areas, and separate means disposed in the annular space between each pair of conducting balls for biasing each pair of conducting balls into contact making engagement with the respective contact areas on the inner surface of the tubular conductor and with said another conductor.

5. A combination as claimed in claim 4, wherein the portion of the inner surface of the tubular conductor includes a plurality of axially extending grooves intermediate the beveled ends with each pair of balls being at least partially disposed in one of the grooves.

6. A combination as claimed in claim 4, wherein a separate means is provided between the plurality of pairs of balls and the inner surface of the tubular conductor for maintaining the pairs of balls in spaced relation around the periphery of said another conductor.

7. A current conducting assembly comprising a generally cylindrical, electrically conducting member having a central opening extending therethr-ough, an electrically conducting shaft disposed to passthrough the central opening and being relatively movable with respect to the conducting member, at least part of said central opening enlarged to define an annular space between the conducting member and the conducting shaft, the portions of the conducting member adjacent the opposite ends of the annular space oppositely beveled at an angle of substantially 45 with respect to the longitudinal dimension of the shaft to define two spaced contact areas on the conducting member, a plurality of pairs of spaced conducting balls disposed around the periphery of the shaft in the annular space and separate means for biasing each pair of balls apart into contact making engagement with 7 both the shaft and the respective contact areas of the conducting member.

8. A combination as claimed in claim 7 wherein means is provided intermediate the plurality of pairs of balls I and the conducting member for retaining the pairs of balls in spaced relation around the periphery of the shaft.

9. A circuit interrupter comprising a tubular electrical conductor having an inner surface, another electrical conductor disposed within the tubular conductor, at least one of the conductors being movable with respect to the other conductor, contact means mounted on the movable conductor for movement therewith, a relatively stationary contact disposed in the path of movement of the movable contact means for engagement therewith and for disengagement therefrom, a portion of the inner surface of the tubular conductor formed to provide an annular space between the conductors, the ends of the portion oppositely chamfered to provide two space contact areas on the inner surface of the tubular conductor, a plurality of pairs of electrically conducting balls spaced along said another conductor and disposed in the annular space around said another conductor adjacent to the respective contact areas, and separate means disposed in the annular space for biasing each pair of balls away from each other into engagement with the respective contact areas and said another conductor.

10. A combination as claimed in claim 9 wherein the ends of the portion of the tubular conductor are oppositely chamfered at an angle of substantially 45 with respect to the longitudinal dimension of said another conductor.

11. A combination as claimed in claim 9, wherein a separate, generally annular member is provided between the inner surface of the tubular conductor and said another conductor for maintaining the respective pairs of balls and the associated biasing means in spaced relation around the periphery of said another conductor.

12. A circuit interrupter comprising a tubular electrical conductor having an inner surface, an electrically conducting shaft disposed within the tubular conductor and being reciprocally movable with respect to the tubular conductor, contact means mounted on the shaft for movement with the shaft, a relatively stationary contact disposed in the path of movement of the movable contact means, a portion of the inner surface of the tubular conductor formed to provide a generally annular space between the tubular conductor and the shaft, at least one end of the portion beveled to provide a contact area on the inner surface of the tubular conductor, a plurality of electrically conducting balls disposed in the annular space around the periphery of the shaft adjacent to the contact area on the inner surface of the tubular conductor, and separate means for biasing each ball into contact making engagement with the contact area on the inner surface of the tubular conductor and with said another conductor.

13. A combination as claimed in claim 12 wherein the inner surface of the tubular conductor includes a plurality of axially extending grooves in which the respective balls are at least partially disposed for maintaining the balls in spaced relation around the shaft.

14. A circuit interrupter comprising a tubular electrical conductor having an inner surface, an electrically con- 8 ducting shaft disposed within the tubular conductor and being reciprocally movable with respect to the tubular conductor, contact means mounted on the shaft for movement with the shaft, a relatively stationary contact disposed in the path of movement of the movable contact means, a portion of the inner surface of the tubular conductor formed to provide a generally annular space between the tubular conductor and the shaft, the ends of the portion oppositely beveled to provide two spaced contact areas on the inner surface of the tubular conductor, a plurality of pairs of electrically conducting balls spaced along the shaft in the annular space adjacent to the respective contact areas, and separate means disposed in the annular space for biasing each pair of balls away from each other into engagement with the respective contact areas and with the shaft.

15. A combination as claimed in claim 13 wherein the inner surface of the tubular conductor includes a plurality of axially extending grooves in which the respective pairs of balls are at least partially disposed for maintaining the pairs of balls in spaced relation around the periphery of the shaft.

16. A circuit interrupter comprising a tubular electrical conductor having an inner surface, an electrically conducting shaft disposed within the tubular conductor, the tubular conductor being rotatable about the shaft, an electrically conducting blade mounted on the tubular conductor for rotation therewith, a relatively stationary contact disposed in the path of movement of the blade for engagement therewith, a portion of the inner surface of the tubular conductor shaped to provide agenerally annular space between the tubular conductor and the shaft, the ends of the portion oppositely chamfered to provide two spaced contact areas on the inner surface of the tubular conductor, a plurality of pairs of electrically conducting balls disposed in the annular space and spaced along the shaft adjacent to the respective contact areas, and separate means disposed in the annular space for biasing each pair of balls away from each other into engagement with the respective contact areas and with the shaft.

17. A combination as claimed in claim 16 wherein the inner surface of the tubular conductor includes a plurality of axially extending grooves in which the respective pairs of balls are at least partially disposed for maintaining the pairs of balls in spaced relation around the periphery of the shaft.

References Cited by the Examiner FOREIGN PATENTS 1,197,958 8/1965 Germany.

References Cited by the Applicant UNITED STATES PATENTS 2,359,055 9/ 1944 Schwager et al. 3,127,492 3/1964 Date.

FOREIGN PATENTS 1,913,394 4/1965 Germany.

0 ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistqnt Examiner,

Claims

1. IN COMBINATION, A TUBULAR ELECTRICAL CONDUCTOR HAVING AN INNER SURFACE, ANOTHER ELECTRICAL CONDUCTOR DISPOSED WITHIN THE TUBULAR CONDUCTOR, AT LEAST ONE OF THE CONDUCTORS BEING MOVABLE WITH RESPECT TO THE OTHER CONDUCTOR, A PORTION OF THE INNER SURFACE OF THE TUBULAR CONDUCTOR SHAPED TO PROVIDE A GENERALLY ANNULAR SPACE BETWEEN THE CONDUCTORS, AT LEAST ONE END OF THE PORTION BEVELED TO PROVIDE A CONTACT AREA ON THE INNER SURFACE OF THE TUBULAR CONDUCTOR, A PLURALITY OF ELECTRICALLY CONDUCTING BALLS DISPOSED IN THE ANNULAR SPACE AROUND THE PERIPHERY OF SAID ANOTHER CONDUCTOR ADJACENT TO THE CONTACT AREA ON THE INNER SURFACE OF THE TUBULAR CONDUCTOR, AND SEPARATE MEANS DISPOSED IN THE ANNULAR SPACE FOR