US2895029A - Electromagnetic device and relay - Google Patents

Description

- July 14, 1959 R. STEINER ELECTROMAGNETIC DEVICE AND RELAY Filed April 10, 1957 N$ II II ELECTROMAGNETIC DEVICE AND RELAY Rudolf Steiner, Van Nuys, Calif.

Application April 10, 1957, Serial No. 652,020

7 Claims. (Cl. 200-104) The majority of the conventional, particularly elec tromagnetic relays has specific undesirable properties, of which the following appear to be the most objectionable ones.

Upon the energizing of the relay coil, mechanical parts remote from the load contacts respond first and transmit a portion of this motion to the load contacts.

Preloaded mechanical springs hold the relay mechanism, but not necessarily. its load contacts in the unenergized position. Upon actuation of the relay to the other, energized position, the mechanical springs are loaded in addition to their initial tension, and the relay armature must then be capable of overcoming these spring forces as well as those of the springs supporting both the movable and stationary contact point of each relay switch.

Traditional relay constructions usually do not comply with the laws of symmetry, which would simplify production, inspection, calibration, attitude and performance.

The employment of substantially stationary contacts causes bouncing effects on contact closing, and of normally or operationally closed relay switches under the eifects of shock, vibration or acceleration.

Usually, no positive action, i.e., no substantially continuous, physically inflexible engagement among all movable mechanical parts is provided.

The normally used ferrous cores and frames constitute dielectric breakdown hazards between the relay operating coil and those members.

The contact gaps are very small, thus often precluding safe contact point separation and circuit interruption, or a dependable open position under conditions of shock, vibration or acceleration.

Theseper se-objectionable relay properties became more detrimental as traditional relay designs were subjected to miniaturization and sub-miniaturization.

Very few, if any relays known in the art have effective means for the quenching of arcs at their load contacts.

The subject of my invention is a device suitable for use as a, particularly electromagnetic relay, a sensing component of a circuit protection apparatus or an electromagnetic release element of mechanisms, having specific characteristics providing improvements over prior art. For reasons of clarity of presentation, the features of my invention will be discussed primarily in the light of electromagnetic relay constructions and applications; however, this shall not be construed as to preclude the suitability of my device for the other, aforementioned possible uses.

The electromagnetic device in accordance with my invention consists, in essence, of a plurality of ferrous, solid or laminated cores, arranged within a coil in such a manner, that optimum utilization of the magnetic field within the energized coil results. Specific cores or core sectors, joined appropriately by means of adequate mechanical members and movable with respect to other such cores or core sectors and viceversa, will be magnetized, if subnited States Patent 2,895,029 Patented July 14, 1959 jected to the field of the coil, to exhibit like magnetic polarities to adjacent movable core sectors and, opposite magnetic polarities to distantly located movable core sec tors. Thus, very effective, combined repulsion and attraction forces will result to cause motion, or rotation, of each core-sector set with respect to the corresponding core-sector set. A mechanical, preferably constant-force spring, installed appropriately between each two such core-sector sets will return the aforementioned assembly, or any plurality thereof provided within the coil space, to the original position upon the de-energizing of the coil. If, as it is diligently presented below, a pivot is arranged for the aforesaid assembly and electrical contacts mounted upon the movable core-sector sets, a relay construction will result having the following, novel and advantageous, major characteristics.

(1) The relay response acts first, and directly, on the circuit interrupting means, i.e., the relay switches.

(2) The relay has distinct on and off contact positions, yet essentially unrestricted as to their locations.

(3) The relay construction is substantially symmetrical and physically balanced and is, further, not complex.

(4) The relay is substantially suitable for D.-C. and A.-C. energization, in essence regardless of the electrical frequency of the respective A.-C. source.

(5) Because of the floating parts arrangement and the absence of stationary electrical contacts, the relay is practically shock and vibration proof.

(6) The relay allows for quick-make and quickbreak contact action, primarily by virtue of the positive parts action of the constiuction.

(7) The relay provides arc-extinguishing means, furnished by the magnetic field of its own energizing coil.

(8) No mechanical spring carries electric current.

(9) No actual mechanical relay frame is employed, thus precluding the most frequent failure source of dielectric breakdown with respect to the coil winding.

(10) The relay uses a maximum possible number of like assembly parts and a minimum possible total number of assembly parts thus permitting eflicient, staightforward and inexpensive production.

The principle of my invention as well as additional novel and advantageous features of my electromagnetic device or, more particularly, of my electromagnetic relay will become apparent from the following description and the accompanying drawing, illustrating but one possible embodiment of a device in accordance with my invention.

In this drawing, forming a part of this application, Fig. l is a schematic diagram portraying the elements of my electromagnetic device, or relay, as well as its operating principle; Fig. 2 is an isometric view, partly in cross section, of a possible electromagnetic relay construction in accordance with my invention and, Fig. 3 is a schematic plan view of an electromagnetic device, or relay, in accordance with my invention, having, for example, two sets of core-sector arrangements within one energizing coil.

Referring now to the drawing, wherein like reference characters designate like or corresponding parts, and particularly to Fig. 1, an electromagnetic coil is shown at 10 having a plurality of turns 12, indicated in crosssection. Within the interior coil space 14, two pairs of identically shaped ferrous, solid or laminated cores 16A, 16B, 18A and 18B are arranged in such a manner, that each two diametrically opposite core sectors are assembled to a rigid member. Thus, the core sectors 16A and 16B are mounted to member 20 and, conversely, the core sectors 18A and 18B are attached to member 22. Each of these connecting members 20, 22 has a thickness of no more than one-half of that of a core sector, thus permitting a cross-over at the physical and geometric center point of the aforesaid assembly, without requiring additional depth. At that center point, a stationary axle 24 is provided, securely mounted to the inside of the coil bobbin barrel (not shown in Fig. 1). The core-sector assemblies are freely rotatable about said axle 24. A preferably constant-force type mechanical extension spring (not shown) will be mounted between one point of core sector 16A and a corresponding point of core sector 18A to cause the core-sector pairs to assume a position substantially as illustrated in Fig. l, or to return to it upon the decay of a magnetic field that may have existed within the coil opening 14. Provided, the coil is energized through, for example, direct current flowing through the turns 12 in the direction indicated by the conventional arrow head and feather symbols within the cross-sectional areas of the coil turns 12, a magnetic field will be created within the coil space 14 shown in dashed lines, having its magnetic north pole at N and its magnetic south pole at S. This field causes the magnetization of the core sectors 16A,, 18A, 18B and MB in the polarity sequence indicated through corresponding letters 11 and s, on the core sectors. It now becomes readily apparent that repulsion results where like magnetic poles face each other, and that attraction exists across core-sector faces having opposite magnetic polarity. This, in turn, will cause rotation of each core-sector pair in a direction opposite with respect to each other, as indicated through the dotted and dashed arrows. Upon deenergization of the coil lit the core-sector pairs will return to their normal, shown, positions by virtue of the aforementioned mechanical spring action.

It further becomes evident that a reversal of the direction of the current flow through the coil turns 12, i.e., opposite to the direction denoted by the arrow head and feather smybols, will cause the magnetic main field N-S to reverse and, likewise, the magnetic polarization of the core sectors. However, like and opposite magnetic polarities will appear at identical locations thus causing identical forces and directions of rotations of each core sector pair per se and with respect to each other as in the previously described example. Because a reversal of the current flow through the coil turns 12 has no operational effect on the described arrangement of my electromagnetic device, or rela its coil 14) can likewise be energized by aternating current, at that essentially of any desired frequency, provided the core sectors are laminated or otherwise suitable for response within an alternating magnetic field.

A possible practical relay construction, in accordance with my invention, is portrayed in Fig. 2. The bobbin of the coil is indicated, partly in section, at 26. The wire turns 12 are arranged within the wiring space provided by the bobbin 26. A stationary axle 24 is installed fixedly across the interior coil space 14. A nonferrous member 2%, having a hole 349 in its geometric center to clear the axle 24, is capable of rotating freely about said axle within the physical limits established by the length of the bobbin opening. The member 28 carries two core sectors 16A and 16B attached securely thereto by means of rivets 32. or equivalent fasteners. Four, for example square holes 34A, 36A, 36B and 34B are punched through said member 23, allowing for the installation of contact supports 38 through wire clamps 40 or other means known in the art. Each contact support carries one contact point 42 to which an extra-flexible, stranded-wire lead 44 is connected, leading to its wiring terminal 46, located at appropriate positions, such as on the top 27 to the coil bobbin 26. The terminals 48 and 5t} serve as coil connections. Facing the member 28 is an identical one 28A, however in a position rotated for 180 degrees about a horizontal axis with respect to the member 28, shown in full. A preloaded mechanical, preferably constant-force type, extension spring 29 is positioned between an ear 3]. attached to member 23 and a corresponding ear (not shown) of member (28A). Referring now to the arrangement of the square holes 34A, 36A, 36B and 34B within the members 28, 28A, one pair of holes 34A and 34B is substantially parallel to the main axis of the member 28 or 28A, whereas the hole pair 36A and 36B is aligned with a radius, through the center 24 and spaced for a specific arcuate distance from the respective holes 34A and MB. This design allows for the arrangement of normally closed and normally open contacts. Through installation of a contact support 38 in hole 34A of member 23 and another support 38 in the corresponding hole of member 28A a normally-closed contact is established, whereas a normally-open contact appears at the opposite end of member 28 through the use of the radially oriented square hole 368 and the corresponding, likewise radially oriented hole 36B of member 23A. This diversified contact arrangement is made possible through the use of only two, identical members 28, equipped with a plurality of, likewise identical contact supports 38 and their fastening means, speaking in terms of production and assembly. It is obvious, that the angular or arcuate displacement of the two square holes at any one end of the member 28 or the member group 28, 28A is a measure for the contact gap of the relay and it is evident that the contact gap may be made essentially as large as desired or required, quite contrary to the situation found to exist with conventional relays. The design of the core sectors 16A, 16B, 18A and 18B is correlated with that of the arrangement of the square holes 34A, 34B, 36A and 3613 in such a manner that specific faces of such core sectors are in close proximity with respect to each other 52, but others spaced further apart from each other 54 at locations perpendicular from the former. Considering the mode of the core-sector installation, the functioning of the device now becomes self-explanatory. It should be noted that the spaces 52 are adequately large to allow for contact Wear, without ever permitting intimate contact of any two adjacent core faces at locations such as shown at 52. Conversely, the spaces of the variety 54 are adequately large to allow for the completion of the contact travel across the gap and for any wear of these contacts. Both space varieties 52 and 54 are designed to consider variations due to parts tolerances, play about the axle 2d and other, intangible factors that normally complicate fabrication, assembly, calibration, testing and the operation of relays or electromagnetic devices in general.

Because the embodiment of my invention, described in the foregoing and shown in Fig. 2 varies but insignificantly from the elementary illustration of Fig. 1, on which the presentation of the new operating principle was based, little, if anything need be added to comprehend the functioning of the relay construction indicated in Fig. 2. It may be in order to concentrate on any specific, additional new properties, features or effects resulting from this construction in accordance with my invention.

As a consequence of the design of spaces 52 and 5'4, there will be no freezing of magnetic surfaces nor exhausted travel of magnetic parts. Adequate spare space is available to either preclude the former or maintain the latter, both contrary to traditional relay constructions.

The electrical contacts 42 serve also as contract travel terminations, one type for the other and viceversa, and there are no mechanical stops which would either wear or introduce bounce effects.

The coil is an item substantially independent of the operating mechanism, and viceversa. This allows for the manufacture of mechanism in advance of future coil requirements, amounting to a considerable advantage toward time-saving and inexpensive mass production.

The aforementioned condition further lends itself to a physical isolation of the coil from the operating mechanism. The coil may be made as a self-contained, sealed or molded unit, into the interior of which the independent operating mechanism is inserted and installed. Or, conversely, the operating mechanism may be sealed within alnonferrous, preferably .also nonmetallic enclosure, suitable for insertion into theinterior coil space. Moreover, both components may-be sealed in one fashion or another and assembled as-described before. In either case, the escape of gases from the coil or the contamination of the electrical contacts will be prevented which is an important factor if relays are to operate dependably in socalled dry circuits, frequently used in the field of electronics. It is also possible to seal coil and operating mechanism within one enclosure common to both components, whereby each component may be an individually sealed unit.

The core sectors may be sold or laminated ferrous units suitable for magnetization and demagnetization, for use with general-purpose devices or relays. With this arrangement, formerly unknown and unavailable relay operations will result, such as a very close differential be- .tween the so-called pick-up and dropout levels, which is imperative for use with specific delicate electronic circuits. However, if permanent-magnet core sectors are used in place of soft-iron cores, a variety of additional relay applications will present itself, such as those for over-"voltage, undervoltage, overcurrent, undercurrent, reversed voltage or reversed current sensing.

Particularly the illustration of Fig. 2 permits the observation of naturally, yet newly provided arc-extinguishing means, consisting of magnetic blow-out action available from the magnetic field extending beyond the coil facesinto the arcing zones of the contacts. It should be noted that this feature is in accordance with the invention, normally available not only for the period of time in which the relay contacts move but also for a period preceding and following the contact transit. This novel arrangement will insure effective arc suppression at all times.

Through adequate jumpers placed across specific relay contact terminals, the basic relay construction presented in Fig. 2 may be converted, for example, from a twopole, one .a normally open, the other a normally closed contact, to a single-pole double-throw contact type relay. Numerous other circuit-transfer variations appear to be feasible tothose familiar with this art.

The aforementioned two-contact or single-pole, double- .throw contact relay can readily be extended to a multipole relay having contacts of any of the two foregoing varieties. A possible construction of such a type is shown, schematically, in Fig. 3, whereby corresponding reference numerals or characters indicate a plurality of previously described relay parts arranged within the, now wider coil 10. All novel features, advantages and performance characteristics which were itemized before for the single- .unit relay, will be recognized in this extended construction. However, the illustration of a two-unit relay in 'Fig. 3 shall not be construed as a limit of the number of contacts or contact'varieties possible within the frame of my invention.

If a contact wiping action, an almost indispensable feature with traditional relays having minute contact movements or openings, should be added, it can readily be incorporated by providing either an excessive play between the diameters of the clearance holes of the members 20 and 22 and the diameter of the axle 24, or by arranging two axles in close horizontal proximity and parallel to each other, each carrying one core-sector pair. The employment of, for example, one solid and one hollow axle, one partly and eccentrically telescoped within the other, may be a suitable construction therefor. Such a configuration will furnish random mating of surface points of the electrical contacts at each engagement and as these contacts eventually assume a balanced position with respect to the magnetic forces acting upon them, wiping action results.

To increase the effectiveness of the aforesaid relay constructions, external, stationary magnetic circuits may be provided, as shown in phantom lines in Fig. 1, extending,

forexample, from the periphery of the core sector 16A, about the coil 10, to the periphery of the core sector 18B, and another equivalent one from the periphery of core sector 18A, about the other side of coil 10, to that of core sector 16B. Other magnetic circuit designs may be utilized to attain various effects or to suit particular requirements.

It is obvious that the described device and constructions can be employed advantageously as sensing and release or locking means for a multitude of mechanical and electromechanical apparatus, such as for mechanical actuators and drives, for electrical switchgear and electromagnetically controlled accessories, to mention but a few.

It is understood that the parts designs, constructions and variations described herein represent but basic embodiments of my electromagnetic device or more particularly, my electromagnetic relay, and that numerous modifications, alterations and rearrangements thereof are possible without departing from the spirit of my invention.

What is claimed is:

1. An electromagnetic device, such as an electromagnetic relay comprising an energizing coil, a plurality of rotatably mounted contact assembly members arranged, in pairs, within the interior of said energizing coil, each such member being equipped with electrical contacts and pairs of cores of magnetic material fastened to each of the respective members, each such pair of members being held in one mutually extreme position by action of a mechanical spring, installed appropriately among each said pair of members, when said coil is not electrically energized, and capable of being actuated to the other mutually extreme position if magnetized by means of a magnetic field created within the interior of the electrically energized coil in such a manner that, upon energizing of said coil and subsequent magnetization of said cores a concerted and effective composition of magnetic repulsion and attraction forces results producing two torques having directions opposite with respect to each other thus causing specific magnetized cores and members to which said cores are fastened to rotate in one direction and corresponding other, likewise magnetized cores and members to which these cores are fastened to rotate in a direction opposite with respect to the former members, thus overcoming the biasing force of the mechanical springs, and the opening of formerly closed, or the closing of formerly open contacts or the transfer of contact arrangements, said contacts provided in physically rigid, electrically insulated combinations with said rotatable members.

2. An electromagnetic device, such as an electromagnetic relay comprising an axle or pivot pin located substantially centrally within an electromagnetic coil, identically shaped nonferrous members arranged rotatably and in pairs in invertedly opposed positions along said axle or pivot pin, a mechanical spring provided among each such member pair to maintain one of two electrical contact positions, pairs of electrical contacts mounted at opposite ends of said members and with respect to the pivot pin whereby one contact of a contact pair is installed to one rotatable member and the other contact of the same contact pair fastened to the other rotatable member of said member pair and positioned in such a manner that one normally-open and one normallyclosed contact pair is obtained at each rotatable member pair, whereby the respectively closed contact pair serves as stroke termination for the open contact pair, sets of pairs of magnetizable cores installed upon the rotatable members in such a manner that each such rotatable member is equipped with two such magnetizable cores positioned diametrically opposed unto each such member allowing thereby for the inverted and interposed positioning of another pair of such magnetizable cores fastened correspondingly to the other, likewise inverted rotatable member of the same rotatable member pair, and said electromagnetic coil encompassing primarily the i magnetizable cores together with the assembly parts by means of and to which said cores are installed whereby an energizing of said electromagnetic coil creates a magnetic field inducing specific magnetic polarities in said magnetizable cores in succession and opposition, respectively, so that like magnetic polarities result at adjacent, and opposite magnetic polarities result at distant, in both cases, physically disassociated core faces, producing two torques having directions opposite with respect to each other by virtue of concerted composition of magnetic repulsion and attraction forces and causing, upon overcoming of the force of said biasing mechanical spring, the opening of formerly closed and the closing of formerly open contacts, or the transfer of contact arrangements.

3. An electromagnetic device, such as an electromagnetic relay comprising an axle or pivot pin located substantially centrally within an electromagnetic coil, identically shaped nonferrous members arranged rotatably and in pairs in invertedly opposed positions along said axle or pivot pin, a mechanical spring provided among each such member pair to maintain one of two electrical contact positions, pairs of electrical contacts mounted at opposite ends of said members with respect to the pivot pin whereby one contact of a contact pair is installed to one rotatable member and the other contact of the same contact pair fastened to the other rotatable member of said member pair and positioned in such a manner that one normally-open and one normallyclosed contact pair is obtained at each rotatable member pair, whereby the respectively closed contact pair serves as a stroke termination for the open contact pair, sets of pairs of permanently magnetized cores installed upon the rotatable members in such a manner that each such rotatable member is equipped with two such permanently magnetized cores positioned diametrically opposed unto each such member allowing thereby for the inverted and interposed positioning of another pair of such permanently magnetized cores fastened correspondingly to the other, likewise inverted rotatable member of the same rotatable member pair, and said electromagnetic coil encompassing primarily the permanently magnetized cores together with the assembly parts by means of and to which said cores are installed, whereby an energizing of said electromagnetic coil creates a magnetic field inducing specific magnetic polarities in and superimposing over the fields of said permanently magnetized cores in succession and opposition, respectively, resulting in a directional relay response depending on the direction of current flow through the energizing coil and the direction of the induced magnetic flux with respect to the direction of the magnetic polarities of the permanently magnetized cores and the magnitude and direction of the force of said biasing mechanical spring, causing either an inactive relay condition or producing two torques having directions opposite with respect to each other because of concerted composition of magnetic repulsion and attraction forces rendering the opening of formerly closed and the closing of formerly open contacts, or the transfer of contact arrangements.

4. An electromagnetic device such as an electromagnetic relay comprising an electromagnetic energizing coil equipped with an electrical wiring terminal board and with mounting provisions, respectively, encompassing, within its interior space a fixedly mounted pivot pin, said pin carrying one or more pairs of members rotatable about said pin, each said member equipped with one of two magnetically responsive core pairs, each core of a pair located centraly with respect to the pivot pin and diametrically opposite with respect to the other of the same member and invertedly interposed by a core of the core pair positioned in an identical fashion upon the other member inverted about a horizontal axis with respect to the former member, said members carrying two pairs of electrical contacts, each contact pair mounted remote with respect to each other and with respect to the pivot pin, each such contact equipped with a flexible, conductive lead and connected to its corresponding wiring terminal, a mechanical biasing spring provided between each pair of rotatable members, said contact pairs disposed in the proximity of the faces of the electromagnetic coil and the main path of the magnetic field established by said coil, whereby, upon the energizing or deenergizing of said electromagnetic coil the opening of formerly closed and the closing of formerly open contacts or the transfer of specific contact arrangements under the arc-quenching eifects of a magnetic blowout action stemming from an increasing, constant or decaying magnetic field of said coil results.

5. An electromagnetic device such as an electromagnetic relay comprising an electromagnetic energizing coil equipped with an electrical wiring terminal board and with mounting provisions, respectively, encompassing, within its interior space a fixedly mounted pivot pin, said pin carrying one or more pairs of members rotatable about said pin, each such member equipped with one of two magnetically responsive core pairs, each core of a pair located centrally with respect to the pivot pin and diametrically opposite with respect to the other of the same member and invertedly interposed by a core of the core pair positioned in an identical fashion upon the other member inverted about a horizontal axis with respect to the former member, said members carrying two pairs of electrical contacts, each contact pair mounted remote with respect to each other and with respect to the pivot pin, each such contact equipped with a flexible, conductive lead and connected to its corresponding wiring terminal, a mechanical biasing spring provided between each pair of rotatable members, said contact pairs disposed in the proximity of the faces of the electromagnetic coil and the main path of the magnetic field established by said coil, whereby, upon energizing or deenergizing of said electromagnetic coil the opening of formerly closed and the closing of formerly open contacts or the transfer of specific contact arrangements under the arc-quenching elfects of a magnetic blowout action stemming from an increasing, constant or decaying magnetic field of said coil results, said relay having stationary cores of magnetizable material positioned externally with respect to said electromagnetic coil and the parts assemblies encompassed by said coil, extending, substantially, from one core sector of one core sector pair to the diametrically opposite core sector of the other core sector pair of the same set of core sector pairs, thus providing an external path of low magnetic reluctance to facilitate the completion of specific magnetic circuits and to increase the effectiveness of the basic magnetic circuit arrangement.

6. An electromagnetic device, such as an electromagnetic relay comprising an enclosed or hermetically sealed electromagnetic energizing coil element and a physically independent, enclosed or hermetically sealed assembly element suitable for insertion into said coil element, encompassing an enclosure having within its interior space a fixedly mounted pivot pin, said pin carrying one or more pairs of members rotatable about said pivot pin, each said member carrying one of two magnetically responsive core sector pairs, each core sector of a pair located centrally with respect to the pivot pin and diametrically opposite with respect to the other on the same member and invertedly interposed by a core sector of a core sector pair positioned in an identical fashion upon the other member inverted about a horizontal axis with respect to the former member, said members carrying two pairs of electrical contacts, each contact pair mounted remote with respect to each other and with respect to the pivot pin, each such contact equipped with a flexible, conductive lead connecting it, electrically insulated, through said enclosure to its corresponding wiring terminal, a mechanical biasing spring provided between each pair of said rotatable members, said contact pairs disposed in the proximity of the faces of the electromagnetic coil and the main path of the magnetic field established by said coil, whereby, upon energizing or deenergizing of said electromagnetic coil the opening of formerly closed and the closing of formerly open contacts or the transfer of specific contact arrangements under the arc-quenching effect of a magnetic blowout action stemming from an increasing, constant or decaying magnetic field of said coil results, said relay having stationary cores of magnetizable material positioned externally with respect to said electromagnetic coil and the parts assemblies encompassed by said coil, extending, substantially, from one core sector of one core sector pair to the diametrically opposite core sector of the other core sector pair of the same set of core sector pairs, thus providing an external path of low magnetic reluctance to facilitate the completion of specific magnetic circuits and to increase the effectiveness of the basic circuit arrangement, the entire assembly being suitable for enlosing or hermetic sealing within another envelope common to both said assembly elements, said common envelope having electrically insulated wiring provisions for said coil and contacts.

7. An electromagnetic device such as an electromagnetic relay comprising physically balanced pairs of electrical contact assemblies arranged rotatably about one stationary pivot pin, said rotatable contact assemblies equipped, correspondingly, with electrical contacts movable together with said contact assemblies, said electrical contacts capable of floating within a plane substantially perpendicular to the axis of said stationary pivot pin, mechanical means for normally maintaining a floating engagement of specific contact pairs and a floating separation, respectively, of other specific contact pairs, each engaged floating contact pair constituting the floating, yet rigid, travel termination for the corresponding open, floating contact pair, pairs of cores of magnetically responsive material fastened to each of the respective contact assemblies, an electromagnetic energizing means for the creation of a magnetic field, said electromagnetic means arranged in such a manner that the magnetic field gen erated thereby surrounds said cores, actuating each said contact assembly and thereby each contact of each contact pair, each such contact assembly, together with each contact of each contact pair and its travel terminations maintaining its floating qualities also in the electron1agnetically energized position, said electrical contacts and said energizing means, respectively, provided with electrical wiring means.

References Cited in the file of this patent UNITED STATES PATENTS 398,927 Balet Mar. 5, 1889 1,871,170 Fryer Aug. 9, 1932 2,495,633 Hayward Jan. 24, 1950 2,570,315 Brewer Oct. 9, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,895,029 July 14, l95

Rudolf Steiner It is herebfi certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 45, for "aternating" read alternating column 5,

line 13, for "sold" read solid column '7, line 68, for 'centraly" read centrally --0 Signed and sealed this 5th day of April 1960.

(SEAL) Attest:

KARL Hg AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION Patent Nos 2,895,029 July 14, 1959 1 1 It is hereb$ certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters\ Patent should read as corrected below.

Rudolf Steiner Column 3, line 45, for ".aternating" read alternating column 5,

line 13, for "sold" read solid column '7, line 68, for "centraly" read centrally Signed and sealed this 5th day of April 1960.

(SEAL) Attest:

KARL Ho AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents

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