US3099503A - Multi-circuit rotary electrical connector - Google Patents

Description

July 30, 1963 A. c. SCOTT MULTI-CIRCUIT ROTARY ELECTRICAL CONNECTOR 2 Sheets-Sheet 1 Filed Dec. 7, 1959 IOc loc

July 30, 1963 A. c. SCOTT 3,099,503

MULTI-CIRCUIT ROTARY ELECTRICAL CONNECTOR Filed Dec. 7, 1959 2 Sheets-Sheet 2 United States Patent 3,099,503 MULTl-CIRCUIT ROTARY ELEQTRICAL CONNECTQR Alec C. Scott, New Hyde Park, N.Y., assignor, by mesne assignments, to Aerollex Laboratories Incorporated,

New York, N.Y., a corporation of Delaware Filed Dec. 7, 1959, Ser. No. 857,639 7 Claims. (Cl. 339-2) This invention relates to multi-circuit rotary electrical connectors and particularly to such connectors designed for a limited range of relative rotation between stator and rotor assemblies.

In many electromechanical systems it becomes necessary to bridge a rotary mechanical joint with a number of electrical circuits carrying power or sensing information, or both. For example, in conventional gyro systems it is necessary to transmit across the pivots of both the inner and outer gimbal rings power for driving the gyro motor and, in addition, it is desired to transmit a number of sensing and control signals developed by the gyro back across the pivots to the electrical system of which the gyro is a part.

Heretofore it has been customary tobridge such rotary joints or pivots by means of conventional slip rings and co-operating sliding brushes or contacts or, in the event the range of relative rotation is limited as in a gyro, by flexible connectors secured directly to both of the relatively moving parts. The former arrangement has the many well-known disadvantages of sliding contacts, such as a relatively high and unstable electrical resistance, a relatively high electrical noise level, etc. The latter arrangement has the disadvantage of possible failure from fatigue after a relatively low number of operating cycles and a requirement of appreciable torque for flexing the connectors, particularly where a large number of circuits must be bridged across the rotary joint.

It is an object of the invention, therefore, to provide a new and improved multi-circuit rotary electrical connector which obviates one or more of the foregoing disad vantages of prior rotary connectors of this general type.

It is another object of the invention to provide a new and improved multi-circuit rotary electrical connector which has one or more of the following characteristics: extremely low operating torque; operation over a large number of cycles without failure from fatigue; and freedom from any sliding or relatively moving contacts.

It is another object of the invention to provide a new and improved multi-oircuit rotary electrical connector which is readily adapted for stacking of a number of elements where the number of circuits to be bridged across the rotary joint is larger than can be readily accommodated by a single connector assembly.

In accordance with the invention, a unitary multi-circuit rotary electrical connector comprises a pair of members of insulation material, one of such members being in the form of a disc, one of such members having provisions for supporting the other member for relative rotation, and one of such members having a central aperture substantially coaxial with the axis of relative rotation. The connector also comprises a plurality of flexible electrical conductors each disposed with its outer end anchored to a fixed point on the disc member near its periphery and with its inner end anchored to a fixed point on the other of the members near the axis of relative rotation of the members, a portion of each of the conductors extending axially through said aperture.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, while its scope will be pointed out in the appended claims.

Patented July 30, 1963 Referring now to the drawings:

FIG. 1 is a plan view of a multi-circuit rotary electrical connector embodying the invention with the cover removed;

FIG. 2 is an exploded longitudinal sectional view of the connector of FIG. 1;

FIG. 3 is a longitudinal sectional view of a stack of four multi-circuit rotary electrical connectors of the type represented in FIGS. 1 and 2; while FIG. 4 is a plan view of a modified form of connector which at present is considered to be the preferred embodiment of the invention.

Referring to FIGS. 1 and 2 of the drawings, there is represented a multi-circuit rotary electrical connector embodying the invention. This connector comprises a pair of members of insulation material 10 and 11 mounted for relative rotation, each having a central aperture substantially coaxial with the axis of relative rotation. For example, the member 10 has a central hub 10a through which extends an aperture 1017, while the other member 11 is in the form of a disc having a central aperture 11a which is journaled on the hub 10a to provide for relative rotation of the members.

The disc member :11 is provided with a plurality of ribs 12 of insulation material disposed on one face thereof as by being seated in the grooves 11b in the face of the disc 11. The ribs 12 and the grooves 111) in which they are seated extend spirally outwardly from the central aperture 11a, thereby forming a plurality of spinal channels therebetween as shown in FIG. 1.

The electrical connector of the invention also comprises a plurality of flexible conductors 13, each disposed in one of the spiral channels with its outer end anchored to a fixed point on the disc 11 at or near its periphery as by the terminal pins 14. The inner end of each of the conductors 13 is anchored to a fixed point on the memher 10 near its aperture. Specifically, as illustrated, all of the conductors 13- extend through the aperture 10b of the member 10, while a disc 15 clamps the conductors 13 to the inner face of the hub 10a, the disc 15 being held in place by any suitable means, such as machine screws 16.

As shown in FIG. 2., all of the conductors 13 extend through the aperture 10b and on to the right, from which suitable connections are made to the associated electrical system. Each of the conductors 13 may be a continuous wire from its associated anchor pin 14, continuing through the spiral channels and the aperture 10!) or, if desired, it may be constituted in two parts joined together at or near the hub 10a in any suitable manner, as by soldering, clamping, or the like. The conductors 13 extending through the central aperture of the connector are, of course, provided with suitable insulation but preferably the portions of the conductors lying in the spiral channels formed by the ribs 12 will be stripped of their insulation, thereby increasing their flexibility and reducing the required operating torque of the connector. However, for clarity in illustration, in FIG. 2 the portions of the conductors 13 lying in such spiral channels are shown unstripped. If desired, a cup-shaped casing member -17 may be secured .to the base member 10 in any desired manner, as by machine screws 18 engaging threaded holes 16c in the member 10. The member 10 may be secured to one memberof the rotary mechanical joint in any desired manner, while a connecting pin 19 secured to the disc member 11 and projecting through an aperture 17a of the casing may be attached to the other member of the rotary mechanical joint in any suitable manner.

It is believed that the operation of the multi-circuit rotary electrical connector of the invention will be apparent from the foregoing description. Briefly, upon rotation of the member '11 by its connecting pin 19 relative to the base member or vice versa, the flexible conductors 13 disposed in the spiral channels between the several insulating ribs will expand from the position in Which they conform closely to the adjacent rib in a clockwise direction (FIG. 1) until they move toward the adjacent rib in the counter-clockwise direction. The range of relative movement accommodated by this flexing of (the conductors 13' will, of course, depend upon the spacing of the insulating ribs and the flexibility and clamping of the individual conductors. However, a rotary electrical connector in accordance with FIGS. 1 and 2 has been found satisfactory for bridging the pivot of a gyro gimbal ring having a rotation relative to its support of :8". Furthermore, it has been found that such a conhector operates over a life of the order of 1,000,000 cycles before failure from fatigue. While the conductors may be constructed of various types and sizes of electrical wire, one embodiment of the invention has utilized stranded copper Wire comprising seven strands of No. 26 wire with overall insulation of tetrafluoroethylene, commercially available under the trade name Teflon.

It will be seen that in the rotary electrical connector described, there are no sliding contacts in completing the electrical circuits between the two relatively rotatable members; that a minimum operating torque is required; and that the device shows freedom from fatigue over a large number of operating cycles.

Another advantage of the 'multi-circuit rotary electrical connector of FIGS. 1 and 2 is that it lends itself readily to the assembly or stacking of a plurality of disc members, such 'as member 11 of FIGS. 1 and 2. A unit comprising an assembly of four disc elements is shown in FIG. 3, in which elements corresponding to those of FIGS. 1 and 2 are identified by the same reference numerals. In this unit the single disc 11 of FIGS. 1 and 2 is replaced by four discs '11, 11 and 11", 11". Since each of these discs and its associated spiral ribs and electrical conductors are the .same as shown in FIGS. 1 and 2, the details need not be further identified. The base member is provided with an elongated inner hub made up of the portion 20a and a series of interlocked rings 21, 22, 23, 24, each of Which clamps the radially extending connectors of its associated disc member to the next right-hand ring or to the hub 20a, as shown. The several rings 21-24, inclusive, are clamped to the hub 20a by any suitable means, such as machine screws 16. The operation of the multi-element rotary electrical connector of FIG. B will be apparent from the foregoing description. It is seen that in this arrangement, the total number of electrical bridging connections is equal to the number accommodated in a single element multiplied by the number of elements in the assembly.

Turning now to FIG. 4, there is represented a modified form of the invention in which elements corresponding to those of the embodiment of FIGS. 1 and 2 are identified by the same reference numerals. In this embodiment the ribs 30 secured to, or moulded as an integral part of, the disc member 31 extend radially outwardly from its central aperture journaled on the hub of the member 29 and forming therebetween a plurality of radial channels. In this form of the invention, each of the electrical conductors is in the form of a resilient narrow conductive strip 32 having one or more U-shaped bends 32a near its outer end. In the specific embodiment illustrated, two of these U-shaped bends extend in opposite directions forming an approximate S configuration. The use of conductors of the described configuration permits disposing them in relatively narrow, sector-shaped slots rather than in the more elaborate spiral slots of the structure of FIGS. 1 and 2, thus permitting the use of a simpler mold. The double bends of spring-like conductors 32, in deflecting, take care of the increased distance between the anchoring points of the terminals of the conductors upon relative rotation between the disc member 31 and the base member 29. The conductors 32 are of material of high conductivity and resilience, for example, beryllium copper. In this embodiment of the invention, the strips 32, which are seen edgewise in FIG. 4, extend through a peripheral ridge 31a of the disc member 31, terminating in connection terminals 33. The conductors 32 also extend through radial slots in the hub 29a of base member 29, While the axially extending conductors 34 are secured to the inner ends of these strips in any suitable fashion, as by soldering. The embodiment of the invention shown in FIG. 4 has all of the advantages of that shown in FIGS. 1 and 2 and, in addition, has shown capability of operation over an even larger number of cycles before failure from fatigue. While the members 29 and 31 of FIG. 4 may be constructed of any suitable material, a tetrafluoroethylene thermosetting plastic commercially available under the trade name Teflon with integral moulded ribs 30 has been found satisfactory. In one embodiment of the invention, the conductors 32 were in the form of 0.003" by 0.125 beryllium-copper strips.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore,

imed in the appended claims to cover all such changes and modifications as fall Within the true spirit and scope of the invention.

What is claimed is:

1. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material, one of said members being in the form of a disc, one of said members having provision-s for supporting the other for relative rotation, and one of said members having a central aperture substantially coaxial with the axis of relative rotation; a plurality of ribs of insulation material disposed on one tace of said disc member and extending outwardly from its central aperture and forming a plurality of channels therebetween; and a plurality of flexible electrical conductors each disposed in one of said channels with its outer end anchored to a fixed point on said disc member near its periphery and with its inner end anchored to a fixed point on the other of said members near said axis of rotation, a portion of each of said conductors extending axially through said aperture.

2. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material, one of said members being in the form of a disc, one of said members having provisions for supporting the other for relative rotation, and one of said members having a central aperture substantially coaxial with the axis of relative rotation; a plurality of ribs of insulation material disposed on one face of said disc member and extending spirally outwardly from its central aperture and forming a plurality of spiral channels therebetween; and a plurality of flexible electrical conductors each disposed in one of said channels with its outer end anchored to a fixed point on said disc member near its periphery and with its inner end anchored to a fixed point on the other of said members near said axis of rotation, a portion of each of said conductors extending axially through said aperture.

3. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material, one of said members being in the form of a disc, one of said members having provisions for supporting the other for relative rotation, and one of said members having a central aperture substantially coaxial with the axis of relative rotation; a plurality of ribs of insulation material disposed on one face of said disc member and extending radially outwardly from its central aperture and forming a plurality of radial channels therebetween; and a plurality of flexible electrical conductors each disposed in one of said channels with its outer end anchored to a fixed point on said disc member near its periphery and with its inner end anchored to a fixed point on the other of said members near said of rotation, .a portion of each of said conductors extending axially through said aperture.

4. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material, one of said members being in the form of a disc, one of said members having provisions for supporting the other for relative rotation, and one of said members having a central aperture substantially coaxial with the axis of relative rotation; and a plurality of resilient conductive strips each having one or more U-shaped transverse bends and each disposed with its outer end anchored to a fixed point on said disc member near its periphery and With its inner end anchored to a fixed point on the other of said members near said axis of rotation, and a conductor connected to each of said strips and extending axially through said aperture.

5. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material, one of said members being in the form of a disc, one of said members having provisions for supporting the other for relative rotation, and one of said members having a central aperture substantially coaxial with the axis of relative rotation; a plurality of ribs of insulation material disposed on one face of said disc member and extending radially outwardly from its central aperture and forming a plurality of radial channels therebetween; and a plurality of resilient conductive strips each having one or more U-shaped transverse bends near its outer end and each disposed in one of said channels with its outer end anchored to a fixed point on said disc member near its periphery and with its inner end anchored to a fixed point on the other of said members near said axis of rotation, and a conductor connected to each of said strips and extending axially through said aperture.

6. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material, one of said members having provisions for supporting. the

other for relative rotation, one of said members having a central aperture substantially coaxial with the axis of relative rotation, and one of said members comprising an assembly of a plurality of discs, each having a plurality of ribs of insulation material disposed on one face thereof and extending radially outwardly from its central aperture and forming .a plurality of channels therebetween; and a plurality of flexible electrical conductors each disposed vvith its outer end anchored to a fixed point on said disc member near its periphery and with its inner end anchored to a fixed point on the other of said members near said axis of rotation, a portion of each of said conductors extending axially through said aperture.

7. A unitary multi-circuit rotary electrical connector comprising: a pair of members of insulation material mounted for relative rotation, one of said members having a central apertured hub and the other of said members comprising an assembly of a plurality of apertured. discs journaled on said hub, each having a plurality of ribs of insulation material disposed on one face thereof and extending outwardly from its aperture and forming a plurality of channels therebetween; and a plurality of flexible electrical conductors each disposed in one of said channels With its outer end anchored to a fixed point on said other member near its periphery and with its inner end anchored to a fixed point on said one member near its aperture, a portion of each of said conductors extending axially through said aperture.

References Cited in the file of this patent UNITED STATES PATENTS 874,979 Murphy Dec. 31, 1907 2,702,889 Bareford Feb. 22, 1955 2,739,289 Droin Mar. 20, 1956 2,955,271 Dawkins Oct. 4, 1960 FOREIGN PATENTS 812,875 Great Britain May 6, 1959 513,269 Italy Feb. 3, 1955

Claims (1)

1. A UNITARY MULTI-CIRCUIT ROTARY ELECTRICAL CONNECTOR COMPRISING: A PAIR OF MEMBERS OF INSULATION MATERIAL, ONE OF SAID MEMBERS BEING IN THE FORM OF A DISC, ONE OF SAID MEMBERS HAVING PROVISIONS FOR SUPPORTING THE OTHER FOR RELATIVE ROTATION, AND ONE OF SAID MEMBERS HAVING A CENTRAL APERTURE SUBSTANTIALLY COAXIAL WITH THE AXIS OF RELATIVE ROTATION; A PLURALITY OF RIBS OF INSULATION MATERIAL DISPOSED ON ONE FACE OF SAID DISC MEMBER AND EXTENDING OUTWARDLY FROM ITS CENTRAL APERTURE AND FORMING A PLURALITY OF CHANNELS THEREBETWEEN; AND A PLURALITY OF FLEXIBLE ELECTRICAL CONDUCTORS EACH DISPOSED IN ONE OF SAID CHANNELS WITH ITS OUTER END ANCHORED TO A FIXED POINT ON SAID DISC MEMBER NEAR ITS PERIPHERY AND WITH ITS INNER END ANCHORED TO A FIXED POINT ON THE OTHER OF SAID MEM-

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