US3384726A - Rotary high-current switch - Google Patents

Description

May 2l, 1968 E. E. KUssMAUl.

ROTARY HIGH-CURRENT SWITCH 5 Sheets-Sheet l Filed April 6, 1966 "ROTARY HIGH-'CURRENT SWITCH 5 Sheets-Sheet 2 Filed April 6, 1966 r (D ID @gig ATTORNEYS May 21, 1968 E. E. KUssMAUL 3,384,726

ROTARY HIGH- CURRENT SWITCH Filed April 6, 1966 5 Sheets-Sheet 3 ATTORNEYS United States Patent O 3,384,726 ROTARY HIGH-CURRENT SWITCH Edwin E. Kussmaul, Westwood, Mass., assignor to Kelek Company, Norwood, Mass., a corporation of Massachusetts Filed Apr. 6, 1966, Ser. No. 540,568 9 Claims. (Cl. 200-155) ABSTRACT OF THE DISCLOSURE A rotary high-current switch comprises a horsing with plural sub-frames within which a rotor has plural longitudinally displaced sections, each section including a part of each of a plurality of mutually insulated conductors. Alternate orientations of the housing sub-frames permit alternate access directions for bus connections to independently mounted bridging type contacts. Current interruption or reversal is effected by connections wholly internal to the housing with minimal movement and within a minimal space.

The present invention relates generally to high current switches, for example switches that may carry up to several tens of thousands of amperes, and more particularly to switches adapted for reversing or transfer of current connections.

In switch applications such as electro-plating it is common to use bridging-type contacts, such contacts being adapted on closing to bridge between the terminals or buses, being held in contact with the latter by spring pressure. Ordinarily a substantial number of such contacts are arranged in a row, and each contact is self-aligning, full-floating and independently mounted so that an even distribution of current load can be obtained even after the contacts have become worn or pitted in use. The preference for bridging-type contacts over the conventional knife-type switch results largely from the smaller space required for the switch and its operating parts.

The bridging-type contact switches hitherto available have had shortcomings in certain applications such as reversing switches. The structural arrangements of bridging-type contact switches are such that they are basically of the single pole, single throw type. The reversing function for a direct current circuit or a single phase alternating current circuit requires four such switches with suitable interconnection-s, such interconnections all being external to and between the switches. Thus the cost of construction and the space required for connecting reversing switches of this type may be considerable, particularly when large currents are to be carried.

It is a principal object of this invention to provide an improved bridging-type contact switch that is capable of reversing one or more current connections with a minimum space requirement and a maximum economy of material, while at the same time providing lall of the known advantages of this type of switch.

A second and related object is to provide a switch that accomplishes current reversal by means wholly internal to the switch structure.

Another object is to Iprovide a switch using a minimum of space, yet being Well adapted for immersion in oil or other cooling iluid to dissipate the heat generated by contact resistance.

Another object is to provide a switch that is so constructed that the load upon its rotary elements is balanced under all conditions, thereby insuring uniform wear and ease of operation either manually or automatically.

Another object is to provide a switch that can accomplish the reversing function with a minimum of mechanical movement of the parts.

3,384,726 Patented May 2l., 1968 ICC Still another object is to provide a switch design that is flexible in regard to the possible orientations of the input and output bus bars.

Having in view the foregoing and other objects hereinafter appearing, the features of this invention include a novel rotary switch having a rotor supported within a housing and including two coaxial, longitudinally displaced sections, these sections each including two conductors and being respectively adapted for electrical connection to the input and output bus bars. Each section of the rotor includes one part of each electrical conductor. Bridging-type contacts resiliently and continuously bear upon the input and output bus bars and the electrical conductors of the rotor, but the contacts are not provided with the usual prior art mechanism for moving them into and out of such contact. Instead of moving the contacts, the present invention contemplates simply rotating the rotor through a given angle which can be arranged either for current breaking or for current reversal or switching, as desired.

Another feature of the invention is that the design of the rotor can be adapted for any desired direction of access for the input and output bus bars. It is only necessary to provide the desired angular displacement between the parts of each conductor in the two sections of the rotor.

Other features of the invention reside in certain details of construction and in modes of operation which will become evident from a study of the embodiments hereinafter described with reference to the appended drawing, in which FIG. l is a side elevation of a preferred embodiment adapted for a rightangle displacement between the input and output bus pairs;

FIG. 2 is an elevation in section taken on line 2 2 of FIG. l;

FG. 3 is a simplified View illustrating the bus connections to the embodiment of FIGS. 1 and 2;

FIG. 4 is a View in perspective of an alternative form of the rotor; and

FIG. 5 is a simplified view showing the bus connections used with the rotor of FIG. 4. f

Referring to FIGS, l, 2 and 3, the preferred form of the switch comprises a housing 12 consisting of two Subframes 14 and 16 each having four bolt holes such as 18, the sub-frames being bolted together by bolts 20. The bolt holes form a square so that the hub-frames can be bolted together in any one of four ways depending on the desired direction of bus access as will become evident from the following description. Each sub-frame comprises four walls 22 of electrically insulating material of any desired type such as laminates impregnated with phenolic resins or the like, the walls 22 being screwed together by screws 24. It will be apparent that this is only an illustrative form of construction, and the sub-frames as well as the frame itself may be built up in any other desired and suitable manner.

The joined sides of the sub-frames each have large circular openings 26, and the opposite walls have smaller openings which form bearings 28 for the shaft ends of a rotor 30. The rotor is of built-up construction and comprises a pair of identical electrical conductors 32 and 34 and an insulating body 36. The parts 32, 34 and 36, when fitted together, form cylinder which extends substantially the full distance between the end bearings 28 within the sub-frames. There is a clearance between the cylinder and the openings 26. Screws 38 are received in radial countersunk holes in the conductors 32 and 34, and are threaded into the insulator 36. These screws are alternated axially of the rotor to prevent electrical connection of the conductors through the screws. Preferably, the conductors 32 and 34 have flat longitudinal grooves adjacent the insulator 36 and pieces of insulation 46 are received in these grooves,

thus increasing the insulation between the ends of the screws 38 and the conductors.

The insulator 36 also preferably has longitudinal slots 42 extending radially inward from the surface, thereby adding substantial length to the surface path between the two conductors. This minimizes the possibility of leakage current tiowing over the surface of the insulator 36 between the conductors.

The insulator 36 has integral shaft extensions 44 and 46 slidably fitting within the bearings 2S. As shown, these extensions comprise fragmentary cylinders with opposed flat surfaces separated by the thickness of the insulator 36, but it is obvious that the shaft extensions can be built up or cast to form fully cylindrical bearing surfaces. Also, while simple sleeves bearings have been shown, it is obvious that thrust bearings and other' types of bearings may be employed. It will be noted that in the preferred form, both the shaft extensions 44 and 46 and the end walls 22 of the sub-frames are made of insulating material. The mechanical load on the bearings, as will hereinafter appear, is balanced so as to reduce wear on the sliding surfaces. The shaft extension 46 is suiiiciently long to receive an operating arm 48 which is secured thereto by screws 50. The arm 48 has a bearing 52 to receive a pin for a clevis connection to a suitable operating crank. This crank may be operated manually or automatically with the aid of pneumatic, hydraulic or electrical power.

Two pairs of bus bars 54 and 56 are respectively received into open ends of the sub-frames 14 and 16, and secured to the side walls 22 by means of screws 58. As shown in FIG. 2, the bus bars extend to positions adjacent but not touching the surface of the rotor 30. Ordinarily, these bars are formed of copper and plated with silver, and are designed to carry considerable currents. The bars 56 may comprise the input connections and the bars 54 may comprises the output connections, or Vice versa, the illustrated form of the invention falling into the generic class of double-pole, double-throw switches connected for current reversal.

Connections from the bus bars to the rotor are accomplished by a number of silver plated at copper contacts such as 60a, each sub-frame having two rows of such contacts. Springs 62 under compression urge the individual contacts against the bus bars and the rotor.

The self-aligning, tull-oating and independent support for the contacts is described as follows. A channel bracket 64 has a number of longitudinally spaced holes, two in the illustrated case, into which are received the reduced ends of threaded adjustment screws 66, the screws 66 being threaded into bushings 68 fitted in the walls of each subframe. The compression springs 62 bear upon the bracket, thereby causing it to conform to the screw adjutrnents at spaced locations along its length. This prevents the bracket from bowing outwardly under the vdistributed spring pressure, and ensures that the springs will be equally compressed and produce substantially equal pressure on all contacts.

Received with in each spring 62 is a tab 69 of a at spacer element 70 having holes for receiving guide rods 72 and 74. These rods tit in blind holes 76 (FIG. 1) in the walls of the sub-frames, and also pass through enlarged holes 78 and 80 in the contacts 60. Each spring 62 bears upon a slightly recessed edge 82 of each of two adjacent contacts, whereby the contacts are continuously urged against the rotor and a bus bar 56. Intermediate spacer plates 83 shaped like the elements 70 but without the tabs 69 are used to complete a loose assembly which restrains the springs and contacts while at the sarne time permitting them to move independently.

The contacts in each sub-frame are diametrcally opposed, and in the form of FIGS. l and 2 the contact pairs in one sub-frame are angularly displaced by 90 degrees in relation to those of the other sub-frame.

Both current reversal and current breaking functions are provided. For example, if a source of direct current is connected between the bus bars 56 which are in turn connected with contacts 60a and tlb (FIG. 2), this source may be connected across the bus bars 54 through the contacts 60C and 60d by turning the rotor 30 in either direction from the position shown in FIG. 2 through a suiiicient angle to bring the contacts 60a and 60b into connection with conductors 32 and 34. Rotation in one direction produces one polarity at the output bus bars, and rotation in the other direction produces the opposite polarity.

Because of the large currents ordinarily carried by this type of switch, it is common to connect it in series with a current-breaking switch that is opened whenever a current reversal is required. However, it is obvious that the present invention can also be used for current breaking where arcing and the attendant pitting of the rotor and contacts present no serious problem.

FIGS. 4 and 5 show how the rotor may be designed to permit the input and output bus bars to enter the switch from different directions than those of FIG. 3. Conductors 84 and 86 are separated by insulation 88, and each conductor has a part in each of two sections and 92 respectively situated within the sub-frames 14 and 16, the parts being angularly displaced in relation to one another by 90 degrees. There is also a mid-section 94 of larger diameter, whereby additional metal is added to the cross-section of each conductor where the parts of the two sections 90 and 92 are connected, reducing the resistance of the current path at this cross-section.

With the rotor of FIG. 4 the sub-frames 14 and 16 are bolted together in the positions shown in FIG. 5, with the result that the input contacts 56 and output contacts 54 are brought into the switch from the same side.

It will be evident from the foregoing description that with the use of the rotor 30 of FIGS. 1 and 2 or the rotor 83 of FIG. 4, the input and output bus bars may be arranged to enter the switch from any one of four different directions, 4making a total of 16 possible arrangements of these connections.

Also, it is obvious that still other arrangements can be devised wherein the displacement between the two parts of each conductor in the rotor can be some angle other than zero degrees or 90 degrees. Also, there can be more than two conductors on the rotor, all mutually separated by bodies of insulation. In such case, there would be an equal number of rows of contacts within each sub-frame, and these contacts would be distributed angularly about the rotor. For example, with three conductors there would be three rows of contacts 60 angularly displaced at 120 degrees.

It will be apparent that various techniques may be employed for cooling the switch. For this purpose the subframes can be suitably modified to retain oil, or the entire assembled switch may be contained within a suitable enclosure iilled with the cooling fluid. Much of the heat is generated by the contact resistance and results in raising the temperature of the rotor. If necessary, the conductors of the rotor can be hollow, with or without their internal surfaces being adapted as heat-exchange tins. Also, it is possible to circulate the cooling iiuid around the rotor since the sub-frames have open sides.

The application of the switch in either direct current or alternating current circuits will be apparent, and alternating current applications may include a plurality of phases. Also, there may be several such switches ganged together on a common shaft.

While the invention has been described with reference to a preferred embodiment, it will be apparent to those skilled in the art that other variations in structure and arrangements of the parts can be accomplished without departing from the spirit or scope of this invention.

Having thus described the invention, I claim:

l. A high current switch having, in combination,

a housing comprising a pair of sub-frames each having provision for connection to a pair of external conductors,

a rotor rotatable in the housing and having a pair of elect-rical conductors and insulation therebetween forming two coaxial, longitudinally displaced sections, one section within each sub-frame, the sections each including a part of one of the conductors forrnc ing a substantial portion of a solid cylinder.

means for interconnecting the sub-frame in a plurality of mutual orientations angularly displaced about the axis of the rotor, and

a pair of pressure contacts for each section supported by the corresponding sub-frame and resiliently urged into contact with the surface of said section, both contacts of one pair being in position to touch the insulation when the contacts of the other pair are each in position to touch a separate conductor.

2. The combination according to claim 1, in which the electrical conductors are of generally semicylindrical shape.

3. The combination according to claim 1, in which one pair of pressure contacts is angularly and longitudinally displaced from the other pair.

4. The combination according to claim 1, in which one pair of pressure contacts is longitudinally but not angularly displaced from the other pair.

5. The combination according to claim 1, with means to turn the rotor between two positions wherein the connections between one pair of contacts and the other are respectively reversed.

6. The combination according to claim l, in which the rotor is supported on an insulating shaft. 5 7. The combination according to claim 1, in which the surfaces of each conductor in the two sections are relatively displaced at right angles about the axis of the rotor. 8. The combination according to claim l, in which the provision for connection to a pair of external conductors comprises a pair of bus bars secured to each sub-frame, each pressure Contact bearing on a bus bar.

9. The combination according to claim 8, and spring means resiliently urging each contact against a bus bar and the rotor.

References Cited UNITED STATES PATENTS 1,146,204 6/1915 Pearce 200-155 20 FOREIGN PATENTS 266,811 3/1927 Great Britain. 709,290 5/1954 Great Britain. 722,941 2/ 1955 Great Britain.

25 ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

Images