GB2140984A - Slip-ring current collector assembly - Google Patents

Abstract

A 2-pole assembly includes a pair of axially spaced apart stationary collector rings (24,23), and a pair of axially spaced apart rotary collector rings (22,25) positioned about the first pair of rings (23,24). A plurality of circumferentially spaced apart contact members (27) are positioned between adjacent stationary and rotary collector rings each of which have a surface (44,50) in sliding contact with the face (35,51) of one of the adjacent rings. A plurality of circumferentially spaced apart springs (45) are positioned between the stationary pair of collector rings (23,24) for biasing the rings in opposite axial directions so that the contacting surface of each contact member (27) is axially loaded. A 12-pole assembly (Fig.5, not shown) may be constructed by mounting additional rings and contacts on the rotating member. The current collector assembly is used to supply current to a cable wound on a reel supplying an overhead crane. <IMAGE>

Description

SPECIFICATION Current collector assembly The present invention relates to current collector assemblies and more particularly to a current collector assembly for conducting electric current to the cable of a take-up reel as the cable is taken in or paid out from the reel.

Various current collect assemblies have been utilized in the past for conducting electric current between rotating and stantionary members. One type of assembly includes a plurality of adjacent annular rings some of which rotate with the rotating members and others of which are stationary. The rings have annular sliding faces which are axially loaded by springs to contact one another and thereby transfer current between the rotating and stationary rings. Exemplary of such prior art collector assemblies are those disclosed in U.S. Patent Nos:3,032,616, 2,983,891, 2,981,916 2,967,216, 2,926,326, 2,774,898, and 2,623,188. All of these assemblies, however, suffer from the disadvantage that the sliding annularfaces of adjacent rings must be precisely manufactured to close tolerances.If two rings, which are not perfectly flat, slide against each other, the magnitude of the contact surfaces area would change constantly. Further, the magnitude of the contact area could also be drastically reduced by the entry of a contaminant or by the build-up of dust caused by wear of the ring faces. Such a reduction in the magnitude of the contact area would result in increased resistance and increased heating which could ultimately result in total failure of the collector assembly. The present invention seeks to provide an improvement.

According to one aspect of the invention there is provided a current collector assembly for conducting electric current between relatively rotating members, comprising: a first collector ring having a face disposed in a plane substantially normal to the axis of rotation of the rotating member; a second collector ring axially spaced from said first collector ring and having a fce disposed in opposition to the face of said first collector ring; mounting means for mounting said first and second collector rings so that said first ring is held against rotation and said second ring is connected to the rotating member to rotate therewith; a plurality of contact members positioned in circumferentially spaced relation between said first and second collector rings, each contact member connected to one of said rings and projecting axially therefrom and having a surface in sliding contact with the face of the other of said rings; and resilient means for axially biasing said contacting surface against the face of said other of said rings.

The contact or plug members in one practical and unique embodiment are disposed circumferentially about the axis of rotation of the assembly and equiangular spaced apart from one another. Preferably, three plugs are used and thus a self-aligning area contact and sliding interface is maintained regardless of any minor variations in the flatness of the ring which the plugs slide against. The plugs thus provide and maintain a positive contact between the first and second rings so that the magnitude of the contact surface area does not fluctuate.

This impedes any bulild-up of undesirable resistance and heating in the assembly. The plugs, besides providing positive contact, provide a wiping action which removes contaminants and dust ahead of the contact surface. Thus, a constant contact area is maintained resulting in an assembly having reliable and predictable performance characteristics.

The collector assembly is relatively inexpensive to manufacture since the use of a three point area of contact enables a reduction in the manfacturing tolerances for many of the components of the assembly. In particular, ring flatness is not critical.

Further, heat that is produced by the resistance of the collector assembly in the sliding contact area is effectively dispersed since the collector assembly resembles a rotating finned heat sink, with maximum exposure of the plug members to the surrounding atmosphere for dissipating heat. Also plug wear can be identified visually and can be easily measured without disassembling the collector assembly.

The plug members are preferably constructed of copper and graphite while the rings are constructed of copper plate. This particular ring/plug material combination combines the excellent current transferring properties of copper/graphTte with the strength of relatively inexpensive copper plate. The plug members are preferably peened or cold soldered in place on one of the rings, and thus since no heat is applied to the rings to secure the plugs, warpage of the rings is minimized.

The spring means of the current collector assembly may include a plurality of compression orfinger washer springs disposed circumferentially about the axis of rotation and equiangularly spaced apart from one another. Preferably, three springs are utilized which maintain three points of pressure against one of the rings. The use of circumferentially spaced plugs and springs provide an effective means for maintaining an acceptable range of plug loading or pressure throughout the life of the plugs. In addition, the use of spaced areas of contact enables the axial loading necessary to maintain the optimum contact life to be reduced in comparison to the much greater spring loading needed if annular rings with their annular contacting surfaces were used as in the prior art.

The mounting means includes bearing means positioned between the rotating member and each stationary ring, and may also include a stud for engaging a projection on the stationary rings to prevent their rotation. The bearing means also provides for limited axial movement or "free floating" of the stationary ring. This "free floating" feature absorbs any deviations in ring flatness as well as any deviations that may be caused by plug wear and manufacturing tolerances. This free floating characteristic is also independendent of any forces induced by the cable hooks-ups. Forces on the stationary ring are absorbed by the stud which prevents rotation and may be isolated from these rings by using flexible shunt wires for connecting the sources of current to the stationary rings.Forces on the rotating rings are isolated from the stationary rings due to the rigid stackup of the rotating rings which is independent of the free floating characteristics of the stationary rings.

In one form, the current collector assembly includes a first pair of axially spaced apart collector rings, a second pair of axially spaced apart collector rings positioned between the first pair of rings, and a plurality of plug members positioned between adjacent first and second collector rings. One pair of rings is held against rotation and the other pair of rings is connected to the rotating member to rotate therewith. Spring means disposed between the second pair of collector rings bias the second collector rings in opposite axial directions to load the contacting surfaces of the plugs against the face of one of the rings. This form of the invention is appropriately termed a 2-pole current collector assembly. Additional "poles" may be added to the assembly by simply stacking additional ring members and plugs along the axis of the rotating member.

The present invention thus provides an efficient device for transferring electric current between relative rotating members which maintains a constant and uniform sliding contact between the members.

The invention will further be described with reference to the accompanying drawings, of which: Figure 1 is a side view in elevation with parts broken away and shown in section illustrating a cable take-up reel incorporating a current collector assembly constructed in accordance with the principles of the present invention; Figure2 is an end view of the current collector assembly shown in Figure 1 taken along the plane of the line 2-2 therein; Figure 3 is cross-sectional view taken along the plane of the line 3-3 of Figure 2; Figure 4 is an exploded view showing the components of the current collector assembly of Figure 1; Figure 5 is a view similar to Figure 3 showing a second embodiment of the current collector assembly of the present invention; Figure 6 is a view taken along the plane of the line 6-6 in Figure 5;; Figure 7 is a view taken along the plane of the line 7-7 in FigureS; and Figure 8 is a view taken along the plane of the line 8-8 in Figure 5.

Referring now to the drawings, Figure 1 illustrates the components of one type of cable take-up reel for use with overhead cranes. The cable take-up reel shown includes a storage drum 1 on which is stored a length of electrical cable 2, a spring motor means 3 and a current collector assembly 4 for connecting cable 2 in an electrical power circuit, not shown.

The storage drum 1 includes a cylindrical core 5 and a pair of parallel spaced apart circular rim members 6 and 7 at either end of core 5 defining an area for storing the length of cable 2 about core 5.

Tubular annular members 8 and 9 are disposed about the rims 6 and 7, respectively, to act as rails and guides for protecting the cable 2 as it is paid out and taken in during operation. The tubular members 8 and 9 are held in fixed relation to the rim members 6 and 7 by suitable bracket means (not shown).

Storage drum 1 is mounted on and affixed to one end of a hollow shaft 10. The other end of hollow shaft 10 supports the collector assembly 4, as will hereinafter be more fully described, Intermediate the ends of hollow shaft 10, and between the collector assembly 4 and drum 1 is a ball bearing assembly 11 which supports shaft 10 for rotation. The opposite end of shaft 10 is connected to a stub shaft 12 which in turn is mounted in a ball bearing assembly 13 carried by the spring motor means 3 which rotatably supports the stub shaft 12 and hollow shaft 10.

Bearing assemblies 11 and 13 are carried buy a pair of spaced upright frame elements 14 and 15, respec tiveiy. Frame members 14 and 15 in turn are mounted to one or more channel members 16 disposed at the base of the take-up reel by means of a pair of foot brackets 17 bolted to the members 14 and 15 and channel member 16. In order to give rigidity to the assembly and to maintain the frame members 14 and 15 in their spaced upright positions, one or more tie rods 18 extending between the members 14 and 15 are provided.

The spring motor means 3 is rotatably mounted on stub shaft 12 through bearing assembly 13 immediately adjacent the upright supporting frame member 15. Spring motor means 3 includes a cylindrical housing 18 disposed about a spring hub member 19, and a coil wind-up spring 20 disposed in the annular space between the spring hub member 19 and the internal side walls of housing 18. The inner end of spring 20 is anchored to hub member 19 and the outer end of spring 20 is anchored to spring housing 18. Thus, rotation of spring hub member 19 in one direction will serve to wind up and tighten spring 20 while rotation thereof in an opposite direction serves to release spring tension. Thus, when spring 20 is tightened or wound up it will tend to drive or rotate the stub shaft 12 to transmit its stored up energy to the storage drum 1 as is conventional.

In addition to the storage drum assembly 1 and the spring motor assembly 3, the cable take-up reel assembly illustrated in Figure 1 includes a current collector assembly 4which is specially constructed in accordance with the teaching of the present invention. The collector assembly 4 is housed within a protective cover 21 carried on the end frame member 14 and includes a plurality of axially spaced apart collector rings 22-25. Collector rings 22-25 are mounted in collect or assembly 4 so that rings 23 and 24 are stationary while rings 22 and 25 rotate along with hollow shaft 10. In the illustrated embodiment of the invention, rings 23 and 24 are separated and biased apart by means of a plurality of spring assemblies 26, and rings 22 and 23 as well as rings 24 and 25 are separated by means of a plurality of current transferring contact, plug or brush members 27. The spring-loaded collector rings in combination with the circumferentially spaced contact plug members provided a balanced current transfer means which maintains a constant and uniform sliding contact surfaces. The spaced contact plug members particularly avoid the necessity of producing and mounting the rings with precise formed and rotating abutting ring surfaces while producing current trans- fez with minimum heat transfer. The collector rings 22 and 25 are each connected by a collector wire or conductor 28a or 28b (Figures 1 and 4) to one of the two conductors 29a or 29b of the multi-conductive cable 2. For example, collector wire 28a may be connected to conductor 29a of cable 2 as illustrated in Figure 3.

In order to connect he collector wires 28a and 28b with the conductors 29a and 29b of cable 2, cable 2 is trained through the interior of hollow shaft 10, as seen best in Figure 1. Hollow shaft 10 provides an opening 30 in order to permit passage of cable 2 from the storage drum 1 to the interior of shaft 10. A clamp 31 may be used to hold cable 2 in place to ensure its proper position with respect to opening 30.

Connection of the collector rings 22 and 23 as well as rings 24 and 25 is provided by the plug members 27 to complete the circuit of the conductors for transfer of power to and from the cable 2. Thus, the rings 23 and 24 are thereby connected to a suitable source of electric current having a pair of individual conductor elements 33 and 34. The individual conductor elements 33 and 34 are each connected to a shunt cable 35 and 36, respectively, which in turn are connected to the stationary collector rings 23 and 24.

Thus, current flows into the assembly 4 via conductor element 33 and shunt cable 35, and flows out of the assembly 4 via shunt cable 36 and conductor element 34, as will hereinafter be described.

Turning now to Figures 2-4, the current collector assembly 4 will now be described in more detail. The current collector assembly 4 includes the axially spaced or stacked collector rings 22-25, the spring assemblies 26 between rings 23 and 24, the plug members 27, and mounting means for mounting the collector rings 22-25 about the rotating hollow shaft 10. As seen best in Figure 4, collector rings 22-25 are flat annular, disc-like structures disposed in a plane substantially normal to the axis of rotation of hollow shaft 10. Each collector ring 22-25 is preferably constructed of copper plate material and has an identical outer diameter. However, as seen best in Figure 4, the inner diameters of rings 22 and 25 are less than the inner diameters of rings 23 and 24, the purpose for which will hereinafter be described.

Collector ring 22 includes a pair of opposite faces 37 and 38 disposed in a plane substantially normal to the axis of rotation of hollow shaft 10. Collector ring 22 also includes three circumferentially arranged and eqiangularly spaced apart bolt-receiving openings 39 formed therethrough adjacent its inner dimater. Ring 22 also includes an opening 40 (see Figure 3) formed therethrough and positioned between a pair of the bolt-receiving openings 39. The opening 40 receives a pressed in stud 41 which connects one end of collector wire 28a thereto. Note that collector wire 28a extends axially from ring 22 and substantially parallel to the rotation axis of shaft 10.

Collector ring 23 also includes a pair of opposite faces 42 and 43 disposed substantially normal to the axis of rotation of hollow shaft 10. When assembled, collector ring 23 is axially spaced from collector ring 22, and face 42 thereof is disposed in opposition to face 38 of collector ring 22. As seen best in Figure 4, collector ring 23 includes three circumferentially arranged and equiangularly spaced apart bush or plug members 27 positioned between the rings 22 and 23 and projecting axially from ring 23. Each plug member 27 is peened or cold soldered to face 42 of ring 23 and is in the form of a thin circular disc. As shown in Figure 3, one side of each plug member 27 is connected to the face 42 of ring 23, and its other side forms a contacting surface 44 which when assembled is in sliding contact with the face 38 of collect or ring 22.Each plug 27 is preferably constructed of a copper/graphite material which provides excellent current transferring properties.

Collector ring 23 also includes three spring assemblies 26 projecting axially from face 43. Sprin assemblies 26 are arranged circumferentially about face 43 and are spaced equiangularly from one another. Each spring assembly 26 includes a compression or coil spring 45 and a cylindrical hollow sleeve 46. Each sleeve 46 is constructed of insulating material and is seated at one end in a countersunk cavity formed in one side of ring 24 in order to be properly located thereon. Each sleeve 46 functions to support and guide the spring 45 which extends through its hollow centre. Each spring 45 has one end seated in a hollow formed in face 43 of collector ring 23 and its other end seated within sleeve 46.

Collector ring 24 also includes a pair of opposite faces 47 and 48 which extend substantially normal to the axis of rotation of hollow shaft 10. As seen best in Figure 3, face 47 of ring 24 is disposed in opposition to the face 43 of ring 23, and has three cavities 49 formed therein for receiving one end of each sleeve 46. Thus, the cavities 49 are arranged circumferentially about face 47 and are spaced equiangularly apart from one another. Face 48 has three plug members 27 projecting axially therefrom which are circumferentially arranged thereon and equiangularly spaced apart from one another. Each plug member 27 is in the form of a thin circular disc having one end peened or cold soldered to collector ring 24 with it other end forming a contacting surface 50 in sliding contactwith one of the faces of collector ring 25, as will hereinafter be described.

Collector ring 25 also provides a pair of opposite faces 51 and 52 which extend substantially normal to the axis of rotation of hollow shaft 10. As seen best in Figure 3, face 51 of collector ring 25 is disposed in opposition to face 48 of ring 24, and is the face which forms the sliding interface with the contacting surface 50 of each plug member 27 projecting from ring 24. As seen best in Figures 2 and 4, collector ring 25 includes three bolt-receiving openings 53 formed therethrough adjacent its inner diameter which are circumferentially arranged and equiangularly spaced apart from one another. Collector ring 25 further includes an opening which receives a pressed in stud 55 for connecting one end of collector wire 28b to face 52 of ring 25. Collector ring 25 also includes a bore 56 formed therethrough positioned between two of the bold-receiving openings 53.As seen best in Figure 3, collector wire 28a projecting from ring 22 extends through bore 56 and for this purpose bore 56 has a diameter slightly greaterthan the diameter of wire 28a so that it might easily accommodate wire 28a. Note that wire 28a includes a protective plastic covering 57 to protect the cable 28 from being frayed by the edge of bore 56.

As seen best in Figures 3 and 4, collector rings 23 and 24 include a stop member 58 projecting radially from its outer circumference. Each stop member 58 is fork-shaped having two spaced prongs 59 forming a slotted opening 60. As seen best in Figures 2 and 4, one of the prongs 59 of each stop member 58 is wider that the other prong 59 and includes an opening for receiving a pressed in stud 61 which attaches the shuntwires 35 abd 36to collector rings 23 and 24, respectively.

The current collector assembly 4 includes means for mounting collector rings 22-25 coaxiallywith respect to hollow shaft 10. The mounting means functions to hold collector rings 23 and 24 against rotation while permitting collector rings 22 and 25 to rotate along with hollow shaft 10. This mounting means includes a metal disc member 62 disposed adjacent to face 37 of collector ring 22. As seen best in Figure 3, disc member 62 includes three steel through bolts 63 projecting axially from its inner face which are circumferentially arranged about its central opening and equiangularly spaced apart. When assembled, each bold 63 extends through corresponding bolt-receiving openings 39 and 53 in rings 22 and 25, respectively. A spacer sleeve 64 constructed of insulating material is positioned between the inner face of disc member 62 and face 37 of ring 22.The spacer sleeve 64 encircles the through bolts 63 and functions to space ring 22 from disc member 62. The mounting means also includes second spacer sleeve 65 extending between the face 51 of ring 25 and the face 38 of ring 22, three nuts 66 which may be tightened down on the free ends of through bolts 63, and three insulating spacer rings 120 extending between the face 52 of ring 25 and the nuts 66. Thus, when nuts 66 are turned down on bolts 63, collector rings 22 and 25 are integrally connected to disc member 62 by means of the bolts 63, spacer rings 120, spacer sleeve 64 and spacer sleeve 65, as seen best in Figure 3. At the same time the bolts 63 are pulled up tight, the proper spring compression or axial loading for plugs 27 is obtained.Springs 45 bias collector rings 23 and 24 in opposite axial directions so that the contacting surfaces 44 and 50 of plug members 27 are pressed and held against the faces 38 and 51 of rings 22 and 25, respectively.

As seen best in Figures 3 and 4, the collector rings 23 and 24 have three nylon bearings 67 disposed on their inner circumference for riding upon the spacer sleeve 65. The nylon bearings 67 are circumferentially arranged about the inner circumference of each ring 23 and 24 and are equianguarly spaced apart from one another. Nylon bearings 67 not only permit rings 23 and 24 to ride on spacer sleeve 65 but also provide for limited axial movement of rings 23 and 24. Thus, as the plug members 27 wear the rings 23 and 24 may be forced further apart from one another by springs 45. This limited axial movement or "free floating" of rings 23 and 24 also permits the springs 45 to absorb any flatness deviation in the face 38 of ring 22 and face 51 of ring 25.

The current collector assembly 24 is of a unitized construction and can be easily assembled on hollow shaft 10 for repair and replacement. To accomplish this, the assembly 4 is merely assembled by positioning the components heretobefore described in their proper locations as shown in Figures 3 and 4 and pulling the bolts 63 up tight. Once this is accomplished the entire assembly 4 may be slid onto the end of hollow shaft 10 and secured in place by a plurality of set screws 68 extending radially through the circumference of disc member 62 to enage shaft 10. As the above procedure is performed, the slotted openings 60 in stop members 58 are positioned to accept a stud or pin 69 extending from upright frame element 14. Thus, collector rings 23 and 24 will be held against rotation and will be permitted to ride on spacer sleeve 65 by means of the insulating bearings 67.

In operation, current will be supplied to stationary collector ring 24 by means of conductor element 33 and through shunt wire 35. Current will then pass through plug members 27 to the rotating collector ring 25 which in turn will transfer current through collector wire 28b to the conductor 29b of cable 2.

Current returns through conductor 29a and collector wire 28a to ring 22, and thence through plug members 27 to ring 23 which in turn passes current through shunt wire 36 to element 34. Thus, as the storage drum 1 is paid out, the rings 22 and 25 will will rotate at the same speed and power will be provided to the electrical cable 2. At the same time, coil spring 20 is tightened so that when it is desired to reel in cable 2 the spring 20 will drive the drum 1 in the opposite direction to take up cable 2.

Referring now to Figures 5-8, there is shown a second embodiment of the current assembly of the present invention. As can be readily observed, Figures 2-4 show a 2-pole current collector assembly. In contrast, Figures 5-8 show a 12-pole current collector assembly. The current collector assembly in Figure 5 includes three sets of groups of axially stacked collector rings, one of which is designated 70. As will hereinafter be described, the set 70 of rings includes eight annular collector rings 73-80 constructed of copper plate, twelve brush or plug members 81 constructed of a copper/graphite material, and three spring finger washers 82 located between collector rings 77 and 76. Each set of group of rings is identical and therefore only set 70 will be described.

As seen best in Figure 6, collector ring 73 is a flat, annular disc-shaped ring which is mounted within a mating channel 83 formed in an annular ring holder 84 constructed of insulating material. The ring 73 includes a lug 85 projecting radially inwardly from its inner circumference. Lug 85 includes an opening 86 which is adapted to receive and mount the end of one of the twelve condustors contained in cable 113.

Figure 6 also shows three plug members 81 arranged circumferentially about ring 73 equiangu larlyspaced apart fro one another. Each plug 81 is suitably secured to and preferably peened or cold soldered to ring 73 and is preferably rectangular in shape, as shown, and projects axially from the face of ring 73. The plug members 81 shown in Figure 6 each have a contacting surface 89 formed by its outer surface which is in sliding contact with the face of collector ring 74, as seen best in Figure 5. The structure and operation of collector ring 80 and its corresponding ring holder 90 and plugs 81 is identical to that described with respect to ring 73 and its holder 84, with the exception that the plugs 81 project in the opposite axial direction, and therefore need not be further described herein.

Collector rings 74 and 75 are substantially identical to rins 73 and 80, and are disposed within corresponding channels 91 and 92 formed in opposite sides of ring holder 93. However, as seen best in Figure 7, each ring 74 and 75 includes a lug 94 projecting radially outwardly from its outer circumference. Each lug 94 includes an opening 95 which is adapted for connection of a shunt wire (not shown) thereto which in turn is connected to a source of electric current. The ring holder 93 is annular in shape and includes a lug 96 projecting radially outwardly from its outer circumference which has a slot 97 formed therein for receiving a pin or stud 98 to prevent rotation of collector rings 74 and 75, as will hereinafter be described.Referring now to Figure 5, it can be seen that the structure of collector rings 78 and 79 as well as their corresponding ring holder 99 are identical to the structure described with respect to rings 74 and 75 and ring holder 93, and therefore will not be further described herein.

Referrring now to Figure 8, collector ring 77 is shown therein. Ring 77 is substantially identical to rings 73 and 80, and includes a lug 100 projecting radially inwardlyfrom its inner diameter having a bore 101 formed therein adapted to receive and mount the end of one of the conductors of cable 113.

Ring 77 is mounted within a corresponding annular channel 102 formed in an annular ring holder 103 constructed of insulating material. Three plug members 81 are cold soldered or peened in place on the face of ring 77 and project axially therefrom. The plug members 81 are circumferentially arranged about ring 77 and are equiangularly spaced apart from one another. As shown, each plug member 81 is rectangular in shape and is constructed of a copper/graphite material which provides excellent current transferring properties. The outer face of each plug member 81 forms a contacting surface 89 which is adapted to be in the sliding contact with the face of collector ring 78, as shown in Figure 5.Figure 5 also shows that ring 76 and its corresponding ring holder 106 is identical to ring 77 and its ring holder 103 with the exception that the plug members 81 extending from the face of ring 76 project in the opposite axial direction from those plug members 81 projecting from ring 77, and therefore will not be further described herein.

Each set of collector rings is identical to the set 70 described above with each set including eight collector rings axially spaced apart by a plurality of plug members 81 so that each set contacts four conductors of cable 113.

The current collector assembly shown in Figure 5 also includes mounting means which functions to assemble the sets of collector rings into a uitized construction and mount the assmbly onto a hollow rotating shaft 107 of a cabletakeup reel. Each set of collector rings is assembled in an identical manner and therefore only the assembly of collector rings 73-80 will be described herein. As shown in Figure 5, the mounting means include an annular disc member 108 having three through bolts 109 extending axially therefrom which are circumferentially arranged and equiangularly spaced apart from one another.The bolts 109 and disc member 108 are substantially identical to the disc member 62 and bolts 63 of the assembly 4 shown in Figures 2-4 with the exception that the through bolts are longer that the bolts 63 so that they can accommodate the increased number of collector rings in this embodiment. The disc member 108 is secured to shaft 107 by means of a plurality of set screws 110 extending radially through its circumference to engage shaft 107. Thus when mounted on shaft 107 disc member 108 and through bolts 109 will rotate therewith.

As seen best in Figure 5, a plurality of cylindrical sleeves 111 constructed of insulating material extend axially between disc member 108 and the end of each bolt 109. A plurality of sleeves 111 surround each through bolt 109 so that the ring holders 84 and 90 are spaced a desired distance apart depending upon the spring loading desired by spring finger washers 82. The inner circumference of ring holders 93 and 99 bear against a pair of drive bearings 112 disposed about bolts 109. Since ring holders 93 and 99 are held stationary by means of pin 98 the bearings 112 are necessary to permit the inner circumference of ring holders 93 and 99 to ride thereon as they rotate.

It should be noted that although ring holders 103 and 106 are rotated along with bearings 112 and bolts 109 there is no structure which prevents holders 103 and 106 from moving axially with respect to shaft 107. This limited axial movement or "free floating" permits the spring finger washers 82 which are disposed between the ring holders 103 and 106 to properly load the collector rings. As seen best in Figure 5, the spring finger washers function to load the ring holders 103 and 106 in opposite axially directions. As a result, the plug members 81 are pressed into sliding contact with the faces of collector rings 74,74,78 and 79 with the length of sleeve 111 controlling the amount of axial loading or pressure therebetween. Thus, when each set of collector rings is mounted on the bolts 109 in the positions shown in Figure 5, a nut 114 may be turned down upon the ends of each bolt 109 so that the inner circumference of ring holders 90 and 84 engage the opposite ends of the bearings 112 resulting in the desired axial spring loading for ring holders 99, 103,106 and 93 which will correspondingly load the sliding interface of plug member 81. In addition, the turning down of nuts 114 causes the rigid stackup of all of the rotating holders against disc member 108 so that they turn in unison therewith. Once assembled, ring holders 84,103,106 and 90 and their corresponding rings 73,76,77, and 80 will rotate along with hollow shaft 107. Ring holders 93 and 99, however, will be held stationary and prevented from rotating by means of pin 98.

In the embodiment shown in Figure 5, current from a source is supplied to the stationary collector rings 74,75,78 and 79, and current is transferred through the plug members 81 to the collector rings 73,76,77 and 80 which in turn transfer the current to the collector wires of cable 113 so that as cable 113 is paid out and reeled in power is supplied thereto.

Claims (16)

1. A current collector assembly for conducting electric current between relatively rotating members, comprising: a first collector ring having a face disposed in a plane substantially normal to the axis of rotation of the rotating member; a second collector ring axially spaced from said first collector ring and having a face disposed in opposition to the face of said first collector ring; mounting means for mounting said first and second collector rings so that said first ring is held against rotation and said second ring is connected to the rotating member to rotate therewith; a plurality of contact members positioned in circumferentially spaced relation between said first and second collector rings, each contact member connected to one of said rings and projecting axially therefrom and having a surface is sliding contact with the face of the other of said rings; and resilient means for axially biasing said contacting surface against the face of said other of said rings.

2. The current collector assembly of claim 1, wherein said contact members are disposed circumferentially about said axis of rotation and are equiangularly spaced apart from one another.

3. The current collector assembly of claim 1, wherein said mounting means includes a stop member projecting axially from said first ring, and a fixed pin spaced from and extending parallel to the axis of said rotating member so that said stop member engages said pin to prevent rotation of said first ring.

4. The current collector assembly of claim 1, wherein said resilient means includes a plurality of coil springs disposed circumferentially about said axis of rotation and equiangularly spaced apartfrom one another.

5. A current collector assembly for conducting electric current between relatively rotating members, comprising: a first pair of axially spaced apart collector rings which define a pair of opposing faces, each face disposed in a plane substantially normal to the axis of rotation of said rotating member; a second pair of axially spaced apart collector rings positioned between the first pair of rings, each of said second collector rings having a face disposed in opposition to the faces of said first collector rings; mounting means for mounting said first and second pairs of collector rings on said rotating member so that one pair of rings is held against rotation and the other pair of rings is connected to the rotating member to rotate therewith; a plurality of contact members positioned between adjacent first and second collector rings, each contact member connected to one of said adjacent rings and projecting axially therefrom and having a surface in sliding contact with the face of the other of said adjacent collector rings; and resilient means disposed between the second pair of collector rings for biasing said second pair of collector rings in opposite axial directions so that the contacting surface of each of said plug members is pressed against the face of the other of said adjacent rings.

6. The current collector assembly of claim 5, wherein said contact members are disposed circumferentially about said axis of rotation and are equiangularly spaced apart from one another.

7. The current collector assembly of claim 5, wherein said mounting means include bearing means between said rotating member and each ring of said one pair of rings which provides for limited axial movement of said one pair of rings.

8. The current collector assembly of claim 5, wherein said resilient means includes a plurality of coil springs disposed circumferentially about said axis of rotation and equiangularly spaced apart from one another.

9. The current collector assembly of claim 7, wherein said mounting means further includes a stop member projecting radially from each ring of said one pair of rings, and a fixed pin extending parallel to the axis of rotation and spaced therefrom so that said stop members engage said pin to prevent rotation of said one pair of rings.

10. The current collector assembly of claim 5, wherein -said first pair of rings rotate and said second pair of rings are stationary.

11. The current collector assembly of claim 5, wherein said first pair of rings are stationary and said second pair of rings rotate.

12. The current collector assembly of claim 11, further includes a third pair of collector rings axially spaced apart so that said first and second pairs of rings are positioned therebetween, said third pair of ring mounted to rotate with said second pair of rings, and a plurality of contact members positioned between adjacent first and third collector rings.

13. The current collector assembly of claim 12, wherein said resilient means includes a plurality of spring finger washers disposed circumferentially about said axis of rotation and equiangularly spaced apart from one another.

14. The current collector assembly of claim 9, wherein said stop member further includes terminal means located thereon for connection to an electrical conductor.

15. A current collector assembly for conducting electic current between relatively rotating members, compsiring: first and second opposed collector ring members at ieast one of which has a substantially planar face disposed in a plane substantially normal to an axis of rotation; mounting means for mounting said first and second collector rings so that one of said rings is held and the other of said rings adapted to be connected to rotate on said axis of rotation; a plurality of contact members positioned in circumferentiallyspaced relation between said first and second collector ring members and having a planar surface in sliding engagement with the planar face of said one ring member to define a current path between said ring members; and means for axially biasing said planar surface and said planar face in said sliding engagement.

16. A current collector assembly substantantially as hereinbefore described with reference to Figures 1 to 4 or to Figures 5 to 8 of the accompanying drawings.