US3024334A - Ball contacting device - Google Patents

Description

March 6, 1962 Filed Sept. 12 1958 c. R. RHODES 3,024,334

BALL CONTACTING DEVICE 2 Sheets-Sheet 1 INVENTOR. CHESTER R. RHODES BY KM AGENT March 1962 c. R. RHODES 3,024,334

BALL CONTACTING DEVICE Filed Sept. 12, 1958 2 Sheets-Sheet 2 FIG. 2.

FIG. 3.

INVENTOR. CHESTER R.RHODE$ United Statcs Patent Ofiice Patented Mar. 6, 1962 g 3,024,334 BALL CONTACTING DEVICE Chester R. Rhodes, Whittier, Califi, assignor, by mesne assignments, to I-Iurletron Incorporated, Danville, Ill., a corporation of Delaware Filed Sept. 12, 1953, Ser. No. 760,601 6 Claims. (Q1. 200-166) My invention relates to electrical contacting devices and particularly to such devices where contact is made and broken by a rolling conductive ball.

Electrical contact has been made by butting or sliding conductive surfaces since antiquity. Either the excellence of the electrical contact has left something to be desired or the power required to slide the conductive surfaces has been greater than desired to perform the es sential function.

I establish a rolling contact by moving a conductive sphere in a groove. Portions of this groove are of insulating material and portions are flanked by conductive material. The sphere makes electrical contact with the conductive material when in physical contact therewith and so connects opposed contacts. When the sphere is in contact with insulating material the contacts are not connected. Accordingly, it is only necessary to provide resilient means to retain the sphere in the groove while moving it along the groove by rolling in order to provide an on-ofr switch.

This type of electrical contact has numerous advantages. The area of the sphere used for the electrical contact is only a small fraction of the total surface area. The sphere is thus the equivalent of a great number of spare contacts. These are constantly interchanged as the contactor is operated.

It is possible to alter the shape of the groove from that which makes contact at the sides of the sphere to that which causes contact with the insulation at the bottom of the sphere. This staggers the conductive tracking with respect to the non-conducting path and so eliminates conductive deposits along the latter. Such deposits cause ultimate failure of the ordinary switch.

It has been customary to provide watt electrical energization of the electromagnetic actuator per pole switched in conventional relay practice. I am able to actuate six poles with one watt of electrical energy; an increase in functional efliciency of four and one-half times.

These advantages have been manifest in long life. The conventional relay 'has a life of the order of 100,000 operations. My device has still been operative after 20,000,000 operations.

Sensitive relays are usually rated at two amperes per contact. With an eighth inch diameter ball my switch may be rated at five amperes.

As will be later apparent, this type of ball switch may fabricated in a number of embodiments which meet several applications to which electrical contactors are be the put.

An object of my invention is to provide an electrical contacting device in which a rolling member makes contact with two stationary contacts.

Another object is to provide a contact which has a large surface, only a portion of which is utilized at any one time to establish electrical continuity.

Another object is to provide an electrical contactor requiring only a small fraction of the mechanical energy heretofore employed to open or close contact.

Another object is to provide a contacting device in which mechanical tracking over the same path on condoctor and insulator does not occur.

Another object is to provide a contacting arrangement which has extremely long life.

Another object is to provide a contactor which is relatively simple and which is inexpensive to manufacture.

Other objects will become apparent upon reading the following detailed specification and upon examining the accompanying drawings, in which are set forth by way of illustration and example certain embodiments of my invention.

FIG. 1 shows an enlarged perspective view of the basic contact,

FIG. 2 shows a sectional elevation view of a relay structure employing my ball contact,

FIG. 3 is a transverse split sectional view of the relay structure showing both magnetic and contacting details,

FIG. 4 is a fragmentary plan view of an alternate arrangement of my ball contacting device,

FIG. 5 shows a fragmentary plan view of a stepping switch employing my ball contacts, and

FIG. 6 is an elevation view of the stepping switch of FIG. 5.

In FIG. 1 numeral 1 indicates the ball or sphere, which is the moving contact. This rolls in a V-like groove 2. It is held in the groove by spring 3, which in turn is held in a movable element such as the arma ture of a relay. This element is not shown in FIG. 1 but the retaining force which it exerts is represented by arrow 4. The force 4 is of the order of 70 grams for an eighth inch diameter ball and it is resiliently maintained upon the sphere by slight deformation of flaps 5 of spring 3.

The insulating member 6 is the basic material in which the track or groove 2 is cut. This is usually circular. The segment shown in FIG. 1 is small and the curvature of the track is not noted.

Two metallic, or at least conductive, inserts 7 and 8 are opposite each other at a particular point in the groove, as usually dictated by the end of travel of an armature, a detent of a multiposition switch, etc. The inserts extend down the sloping sides of the groove in order to make contact with ball 1 when it passes. The portions which extend away from the groove are not necessary to accomplish the switching function but are convenient for attaching external connections. These are not shown in FIG. 1.

The basic arrangement shown in FIG. 1 constitutes a single-pole single throw switch configuration. When sphere 1 is on the insulated portion of groove Z, as shown, the switch is open. When it is between conductive contacts 7 and 8 the switch is closed.

For a single-pole double-throw switch, stationary contact 7, for instance, is extended twice as far along the groove and another contact, 8, is placed adjacent to, but not touching, contact '8 on that side of the groove. Contact 7 then becomes the arm or common of the switch. Contact 8 is contacted on one throw of the switch and contact 8' on the other throw.

In the same manner, a single-pole multiple-throw switch is formed by still further extending contact 7 and providing contacts 8", 8", etc.

Where more than one pole is desired, additional balls with coacting stationary contacts adjacent to each are provided. For example, a six-pole double-throw switch or relay can easily be fabricated by employing six spheres, twelve contacts 8 and six extended contacts 7 around the circumference of a full circle groove 2. Such a configuration can be augmented by providing two grooves, and so on. It will be appreciated that almost any combination and complexity of switching function can be accomplished with my structure.

In fabricating my contacting device the groove 2 can be proportioned to ride the ball exclusively on the slanting sides. This is required at the conducting contacts, as 7 and 8. On the other hand, for non-tracking of the contact ball from the contacts to the insulating material ad- 3 jacent in the groove the bottom of the groove is made a few thousandths of an inch shallower than is required for rolling contact at the slanting sides. This causes, of course, rolling contact at the bottom of the groove on the insulation. Where the inserted conducting portions 7, 8, etc. are located the sides of the groove are made closer together than before by a few thousands of an inch. This causes contact with the ball at the slanting sides and not at the bottom of the groove. In this way non-tracking is accomplished.

In practice, the slightly projecting metal contacts can be obtained by merely machining the groove in essentially the usual way. The groove-cutting tool, the resiliency of the insulating material and the toughness of the metal are adjusted so that in the machining process the metal cont acts are forced slightly backwards away from the groove, but return a few thousandths of an inch when the cutting tool has passed.

It is also possible to accomplish the same proportions by plating the metal contacts on the sides of groove 2 and on the surface of insulating member 6 according to the techniques of printed or etched circuit wiring.

A practical embodiment of my ball contacting device is illustrated in the form of a relay as shown in FIGS. 2 and 3. A central core 12 of magnetic material has scalloped end disks 13 and 14, upper boss .15 and lower tubular extension 16. This is preferably one piece of material. A coil of insulated wire 17 is wound around core 12 between end disks 13 and 14. When energized with-electric current this coil provides the magnetomotive force to actuate the relay.

Surrounding this structure is an armature composed of bottom disk 18, top disk 19, and plural slats, of which two, 20 and 21, are seen in FIG. 2. The bottom disk is preferably fabricated of a suitable insulator, such as diall pthalate, since the ball-retaining springs 22 are held therein and'an electrical connection from one ball to another is to be avoided except in a very specialized kind of connection between the otherwise electrically separate poles of the relay. For uniformity of expansion, etc. under conditions of varying temperature, upper disk 19 is preferably fabricated of the same material as lower disk 18, although it may be fabricated from a non-magnetic material such as brass. Disk 18 is provided with a bronze sleeve bearing 23 and disk 19 with a similar bearing 24. These journal the armature structure around bosses 15 and 16 of core 12. Oilite may be used as the bronze material to obviate lubrication maintenance.

The significance of the magnetic structure is revealed at the left hand side of FIG. 3, where the scallops of end disk 14 are seen. Coactive slats 21 and 25, of magnetic material, and lower disk 13 are seen to be disposed so that energization of coil 17 causes rotation of the armature in the direction of the arrow 26. This motion takes place because the magnetic reluctance between the rotating and stationary magnetic structures is reduced thereby.

A six pole relay is shown, thus the rotation required is less than i.e., about 24, for the contacts shown in the right hand portion of FIG. 3. A plurality of spheres 26 are shown, each \w'th a group of three contacts; 27, 28 for the separate throws of the switch and 29 for the common pole. With the rotation previously noted in the direction 26' spheres 26 will be rotated between the two contacts 27 and 28 in each instance. A spring 39, fastened under tension-adjusting screw 31 at the top of the rotating structure and to the stationary structure in boss 15 provides the restoring torque to return the magnetic structure to a high reluctance position. Simple mechanical stops at both extremes of travel desired; i.e., coil 17 excited and full restoration by spring 39. These stops are not shown in the figures for sake of simplicity, but may be positioned to strike the hollow portions of a scallop on element 14 as shown in FIG. 3. By altering the radial position of such a stop it will be appreciated that the travel can be adjusted as required.

In this relay embodiment he insulating member in which the groove is cut is identified by numeral 3d. The several insert contacts 27, 28, 29 are held in intimate contact with the insulating member and are provided with external connections by hook terminals 31, 32; the former connecting to the outer contacts 27, and the latter to the inner contacts 29'. The terminals are integral parts in glass inserts 33 of a metal header 34, which latter forms the lower enclosure of the relay. The contacts may be structurally and electrically connected to the terminals by silver soldering. Two additional terminals, of which one, 35, is shown in FIG. 2, are employed to connect the two ends of coil 17 to external circuits.

The header-insulating member assembly is fastened to core 12 by central screw 36. This screw is threaded into the lower tubular extension 16 of core 12 and may be locked in place by a setting plastic over the head thereof. An outer case or housing 37 is provided to enclose the device and may be fastened to header 34 by soldering for a hermetically sealed unit. The magnetic slats, as 21, may be fastened to end disks 1.8 and r3 by fiat head screws 33.

Other contact configurations may be employed in this relay, as can easily be visualized by applying the embodiments previously stated in connection with PK 1 to the example given at the right-hand side of FIG. 3.

FIG. 4 shows an alternate manner of actuating the spheres of my devices. Shafts 40 have been characterized as skewers in mounting spheres 41 to a central rotative hub 42. The skewers pass through holes in the spheres and are provided with heads 53 and collars 44, which give a loose longitudinal fit of the sphere on the skewer. The mechanically constraining element is still the groove 45, as it has been before. The head and the collar in the present instance are safety elements to insure that the sphere will not depart from the groove under the influence of an unusual force or condition imposed upon the device in assembly or in use. The skewers are fabricated of a spring-like material such as steel or bronze and are mechanically biased so that a slight tension is exerted downwardly on the spheres to insure tracking in groove 45. This also insures good electrical contact between the spheres and contacts 46, 4'7, 4-8,

In this embodiment a four pole (four spheres)-triple throw switch configuration is shown. (The skewers are at The triple individual contacts are 46, 47, 48, and the common contact is 4-9. The latter is three times as long as one of the individual contacts. All of the contacts are mounted on insulating member 50 along groove 45 in the manner that has been described. A shaft. 51 drives the skewer assembly by magnetomotive or other means not shown. Only a fourth of the whole device is shown in the fragmentary view of FIG. 4, but the sequence for other poles is repetitive.

From FIG. 4 it is easily seen that a six throw switch could be accommodated by multiplying contacts 46, 47, 43 by two; and that by employing narrower contacts, which are altogether feasible, even greater throws may be accomplished. By providing more spheres, alternately, more poles may be had.

A further alternate embodiment of my ball contacting device is shown in FIGS. 5 and 6 in the form of a 24 polc stepping switch.

The basic structure involves a. spring conductive switch arm 55, a common contact track 56, twenty-four separate contacts 57, a pair of spheres 5E5 riding upon the track and another pair of spheres 59, which latter make contact with each of the separate contacts successively. it is seen that the electrical path is from the track, through the switch arm and to one of the separate contacts at any one time.

An insulating member 6% forms the base of the switch structure per se. The track and contacts are either metallic inserts in that member or conductive portions provided by an etched circuit technique or the equivalent. Parspaassa ticularly if inserts are used, a terminal 61 fastened in the member serves to hold the separate contacts in place. Only one of these has been shown in FIG. 6 for sake of clarity.

A shaft 62 is journaled in member 60 and is rigidly attached to structural arm 63. In this manner rotary actuation may be given to the arm by means such as a stepping motor or mechanism, which has not been shown. The structural arm 63 has an aperture for the pair of spheres 58 and another aperture for spheres 59. Spring arm 55 is fastened to the structural arm 63 by two rivets 64 or by equivalent fastenings. This configuration forms an enclosure for each pair of spheres and provides spring pressure to press these down on the track or separate contacts as the case may be. Spring 55 is relieved around the square of shaft 62 so that the latter does not short whatever electrical potential may be given to track 56 as the various separate contacts 57 are contacted.

The two spheres employed at each electrical contact in FIGS. and 6 increase the reliability of such contact. although contact with a single sphere has not been found wanting. It will be understood that the two sphere arrangement may be employed with the skewer arrangement of FIG. 4 by placing two spheres adjacent on each skewer and employing two grooves or flat contacts (as in FIG. 5). A similar modification may be made in FIGS. 2 and 3 and by employing two grooves and radially wide springs 22 capable of retaining two spheres instead of one. No particular sizes of spheres are required to practice this invention, but spheres /s" diameter have been employed in the embodiments of the first four figures and A for FIGS. 5 and 6. Beryllium copper is a suitable material for fabricating springs 22 and spring 55.

Tests have shown the embodiments described to be free of contact bounce or chatter. This is because of my rolling contact rather than the butting contacts of the usual relay.

By employing more than one sphere for each contact grouping comprising one pole it is possible to accomplish make-before-break contacting, double-break contacting, and other contacting sequences.

Various other modifications may be made in the arrangement, size, proportions and shapes of the illustrative embodiments shown and in substitutions of elements from one embodiment to another without departing from the scope of my invention.

Having thus fully described my invention and the manner in which it is to be practiced, I claim:

1. A ball-type electrical contacting device comprising a stationary insulating member, a full-circumference circular slot having a bottom in said member, non-magnetic spherical contacts positioned to traverse said slot, stationary substantially flush-mounted metal contacts dis posed in groups around the outer circumference of said slot, there being one spherical contact for each group of said stationary contacts, said groups separated around said outer circumference to prevent contact between one said spherical contact and more than one of said groups of stationary contacts, an additional substantially stationary flush-mounted contact centrally disposed around the inner circumference of said slot opposite each said group of stationary metal contacts to contact said spherical contact at the same time as said spherical contact contacts any of the stationary contacts of one said group, said stationary contacts mounted in relation to said slot so that said spherical contacts ride upon the sides of said stationary contacts and in the absence of such stationary contacts said spherical contacts ride upon the bottom of said circular slot, a rotatable armature oppositely disposed to said stationary member with respect to said spherical contacts, one radial shaft insulatingly carried by said armature to retain each said spherical contact in said slot and to rotationally traverse said spherical contact circumferentially between separate contacts of a said group upon rotation of said armature a corresponding amount.

2. An electrical contacting device comprising an insulating member; a slot in said insulating member; said slot having walls comprising a bottom and two sloping side walls; a plurality of spaced electrical contacts mounted in opposed relation in said insulating member adjacent to said slot; said electrical contacts forming a portion of and projecting slightly from said side walls of said slot; a sphere of electrically conducting material mounted for rolling motion along said slot, making contact with and riding upon said walls of said slot; said sphere adapted to electrically connect opposed electrical contacts as it moves along said slot; said sphere making contact with only said side walls of said slot where said side walls are formed in part of opposed electrical contacts, and making contact with said bottom of said slot elsewhere.

3. The electrical contacting device of claim 2 wherein said sphere is journalled through a diameter thereof upon a resilient shaft, said sphere being spring biased by the resilience of said shaft toward said slot, whereby it is maintained in contact with the walls thereof.

4. The electrical contacting device of claim 3 wherein said sphere has at least a limited freedom to move along said shaft, and in which the mechanical restraint upon said sphere in the direction of said shaft is supplied by said side walls of said slot.

5. The electrical contacting device of claim 2 wherein said electrical contacts are arranged in a plurality of spaced groups, each said group comprising a plurality of contacts, and wherein a separate sphere corresponds to each said group, whereby said contacting device comprises a multipole device.

6. The electrical contacting device of claim 5 wherein said slot is arcuate, wherein each sphere is journalled through a diameter thereof upon a separate shaft, wherein each said shaft extends radially with respect to said arcuate slot and is attached to a central armature, and wherein said armature is adapted to rotate, thus rotating said shafts and consequently moving said spheres along said slot.

References Cited in the file of this patent UNITED STATES PATENTS 262,260 Tirrell Aug. 8, 1882 392,443 Long Nov. 6, 1888 862,127 Auel Aug. 6, 1907 1,254,331 Blanc Jan. 22, 1918 1,463,974 Schweitzer Aug. 7, 1923 1,577,572 Forder Mar. 23, 1926 1,834,896 Bruno Dec. 1, 1931 2,135,809 Fruth Nov. 8, 1938 2,339,063 Deakin Jan. 11, 1944 2,453,106 Yardeny et al. Nov. 2, 1948 2,754,386 Gaylord July 10, 1956 2,805,291 Eickhorst Sept. 3, 1957 2,817,722 Johnson Dec. 24, 1957 2,834,842 Le Beau May 13, 1958 FOREIGN PATENTS 27,266 France Ian. 29, 1924 319,861 Great Britain Oct. 3, 1929 425,119 Germany Feb. 11, 1926 510,059 Great Britain July 26, 1939 552,793 Great Britain Apr. 23, 1943

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