US 3204057 A
Description (OCR text may contain errors)
Aug. 31, 1965 N. H. MAGIDA 3,204,057
MULTICONTACT EVACUATED MAGNETIC REED RELAY Filed Sept. 11, 1961 2 Sheets-Sheet 1 42 INVENTOR MHz/an Ema o'd'a/ ATTORNEYS Aug. 31, 1965 N. H. MAGIDA MULTICONTACT EVACUATED MAGNETIC REED RELAY Filed Sept. 11, 1961 2 Sheets-Sheet 2 4 INVENTOR N hm Ha m4 mw m6 United States Patent 3,204,057 MULTICONTACT EVACUATED MAGNETIC REED RELAY Nathan H. Magida, Westport, Conn., assignor to Thermosen, Incorporated, Stamford, Conn. Filed Sept. 11, 1961, Ser. No. 137,395 6 Claims. (Cl. 200-87) This invention relates to electromagnetic circuit devices and more particularly to relays, especially multi-polar transfer relays having high operating speeds, and extremely high reliability even though contained in very limited space.
In the past, many relays have been designed as multipolar relays, but as discussed below, they have certain deficiencies. Broadly, these relays are of two general types:
Type 1 has an operating coil which moves a magnetic armature. The armature is connected through an insulating member to one or more sets of contacts which open and close as the armature moves. This is by far the most common type of. relay. It is made in both open and closed designs, the latter being either in a dust-tight housing or in a hermetically-sealed enclosure. In either case, the contacts are subjected to corrosive atmospheres. In the case of open relays, corrosive materials are generally present in the surrounding atmosphere. In the closed or hermetically-sealed type, the surrounding atmosphere has no effect on the contacts, but the gases usually emitted by the coil, or other organic materials inside the hermetically sealed enclosure, may cause corrosion.
Another drawback in a Type 1 relay is the size of the moving mass, which usually includes the armature itself. Because of the mass, the speed of operation of this type of relay is necessarily limited.
To avoid contamination by coil gases, a Type 2 relay has been created. Here, the contacts are mounted on reeds which are deflected by magnetic fields acting upon them. A typical example is the sealed reed switch disclosed in Patent Number 2,289,830, granted July 14, 1942, to W. B. Elwood. Such a switch has a cylindrical enclosure of electrically insulating nonmagnetic material, such as glass, surrounding a pair of reeds extending into the enclosure from opposite ends. The sealed cylinder is filled with an inert gas. The reeds, which are of magnetic material, are positioned to overlap at their inner extremities, but are normally separated by a small space. When a magnetic coil is wrapped around the sealed cylindrical enclosure and the coil is energized, the reeds move towards each other until they meet. It is possible to utilize groups or clusters of such switches within a single coil; such as disclosed in Patent Number 2,243,399, issued May 27, 1941.
As indicated above, the usual sealed reed relay structure has only one pair of normally open contacts in each enclosure. Where normally closed contacts are required, a small permanent bar magnet is mechanically attached to the glass cylinder to maintain the reeds in a closed condition. Then when the outer surrounding magnetic coil is energized, it magnetic field bucks the magnetic field generated by the permanent bar magnet, thereby reducing the magnetic attraction between the two reeds, and thus enabling them to open.
Unfortunately, the characteristics of each individual sealed reed switch cannot easily be modified, once the switch has been assembled. Characteristics, such as amount of magnetic coil current required to close the switch; ratio of this coil current to the amount of current that will just permit the switch to open, etc., are determined by the distance between the two reeds in their open position, and the amount of overlap between the 3,204,057 Patented Aug. 31, 1965 two reeds, as well as the mechanical characteristics of the material of which the reeds themselves are made.
Since the critical spatial relationship between the reeds is determined during the sealing process, very great pains must be taken to insure that the reeds are not only properly aligned but also that the alignment does not change during sealing of the glass enclosure. Expensive and complicated machinery must be used to retain this alignment.
In production runs of assemblies of sealed reed switches, a further complication arises. There is frequently a need to produce several different units with very specific characteristics. For example, when normally open and normally closed contacts are to be used together in an assembly, very great care must be taken in selecting reed switches with proper sensitivity to insure operability. In practice, however, it is almost impossible to guarantee, especially in situations when it is desired, that the normally open contacts will open before the normally closed contact is closed, and vice versa.
In addition to these electrical operating problems, in assembly, the combining of several reed switches results in an assembly which is much larger in size than comparable relays of conventional Type 1 design. They therefore require considerably more coil power for operation.
Accordingly, an object of this invention is to provide a relay whose contact-making surfaces are all enclosed in a sealed container with the magnetic coil external to the container, whereby corrosion of the contacts is avoided and reliable operation over a long life is insured.
Another object of this invention is to provide a relay of the above character having a plurality of contacts within a singular enclosure.
A further object of this invention is to provide a relay of the above character having a high volumetric efiiciency.
A still further object of this invention is to provide a relay of the above character wherein wiping action at the contacts occurs during each energization.
Another object of this invention is to provide a relay of the above character which can be adjusted after assembly but before sealing within the enclosure, to attain the desired final operating characteristics.
Another object is to provide a low cost multi-polar sealed relay of the above character and, in particular, to reduce the need for expensive and complex machinery for its manufacture.
Still another object is to provide a relay of the above character having a contact design which incorporates both normally open and normally closed contacts with positive assurance of any desired sequencing, i.e., that the normally closed contacts will open before the normally open contacts close, or vice versa as may be desired.
Another object is to provide a relay of the above character having a contact design which does not require permanent magnetic biasing to create a relay having normally open and normally closed contacts within the assembly.
Another object is to provide a relay which has an improved magnetic efficiency so that lower coil power is needed for each contact set.
Another object is to provide a relay which eliminates continuous mechanical paths for flux return to the coil, thus realizing further simplification and economy in manufacture.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:
FIG. 1 is a side cross sectional view of a multi-polar embodiment of the relay of this invention,
FIGURE 2 is a top cross sectional view of the relay of FIGURE 1 taken along line 2-2,
FIGURE 3 is a side cross sectional view of the coil energizing circuit structure taken along line 33 of FIGURE 2,
FIGURE 4 is a partial perspective view of one set of contact points,
FIGURES 5 and 6 are sequential side views, greatly enlarged, showing the contact wiping action as the reed travels from the normally closed contact position to engagement with the normally open contact during magnetization of the pole disk.
Similar reference characters refer to similar parts throughout the several views of the drawing.
As best seen in summary detail in FIGURE 1, the relay 10 of this invention broadly consists of an enclosed and preferably hermetically-sealed array of opposed pairs of support-arm contacts with a magnetic reed contact element positioned therebetween. Alternatively, one support arm contact may be used with each reed contact. Each magnetic reed is disposed about a magnetizable pole member 18, so that when the magnetizing coil is energized, the reed will be deflected to make or break engagement with the support arm contacts associated therewith. An enclosure is provided about the contacts to avoid corrosion, whereby good reliability is effected.
More particularly, the relay 10 of this invention, in its preferred form, comprises a single centrally disposed, magnetizable pole member 18, magnetized by coil 22. The pole member is formed of low retentive magnetic material and is situated within contact enclosure 24, which is preferably hermetically sealed. Within the enclosure and spanned around the pole member is an array of magnetic reeds 2t), and adjacent contact support arms 26 and 28, having contacts 16 and 17, 12 and 14, respectively. There may be either one or two support arms adjacent each reed. In the preferred embodiment shown, transfer contacts are provided and when the pole member 18 is energized, the reed 20 is deflected to successively break and make contact with its associated support y arm contacts. The particular structure employed, as explained hereinafter, can be so arranged that the break occurs before the make, or conversely if desired, in certain situations. This unique structure avoids the necessity for custom preselection of reeds, and permits precise alignment of the contact assembly before sealing. In addition, the location of contacts in an enclosure separate from the coil effects increased reliability and prolongs the life of the relay because there is no corrosion. The contact enclosure may be evacuated or back filled with an inert gas. The compact relay structure as shown, permits up to eight single pole, double throw switches to be operated simultaneously, at high speeds, by energization of a single coil.
Referring now to FIGURE 2 of the drawing, it will be seen that the centrally disposed magnetizable pole member 18 is formed in the configuration of a spoked wheel, with each spoke adjacent to the movable end of a magnetic reed. While the pole piece 18 may be formed as an annular disk, or as a multi-sided thin disk, the spoked configuration shown has the advantage of reducing stray flux leakage between the central magnet core and the exterior flux return path. Secured to the lower portion of the pole member 18, is a spacer disk 30 of nonmagnetic and non-conductive material, its func- 4 tion being to insulate the reed 20 from electrically conductive engagement with pole member 18.
The pole member 18 is secured on its top side (as seen in FIGURE 1) to a downward extension of the magnet core 32. The main portion of the core 32 is contained within electrical coil 22. The bottom side of the pole member l8spaced disk 3% assembly, is secured to an axial support rod 34 which is telescoped into a hollow support tube 36. This arrangement provides the necessary axial support for the pole member 13. As seen in FIG- URES 2 and 3, the coil 22 is energized by means of successive pairs of wires 38, conductor strips 39, which are embedded in and extend through the bulkhead 58, a conductor connecting strip 41 and conductor strips 43, which are embedded in and extend through base header 40 of the relay and terminate as tabs 42. These elements are ofiset, as seen in FIGURE 2, with respect to a center dividing line of the relay.
Spaced around the pole member 18, as best seen in FIGURES 2, 4 and 5, is an array of reeds 29 with associated support arms 26 and 28. Each reed has contacts 16 and 17, coacting with support arm contacts 14 and 12, respectively. The support arms 26 and 28 are made of spring conductive material such as Phosphorbronze or beryllium copper, having suitably low electrical resistance. The reeds 20, however, must be made of ferromagnetic material and are preferably selected for high magnetic saturation levels in addition to suitable spring properties. The material of the reeds and support arms can, if desired, be plated with suitable precious metals, such as gold or silver, for further resistance to corrosion. At their lower ends the reeds 20 andsupport arms 26 and 28 are embedded in an insulated header 40, and also terminate externally as tabs 4-2. The tabs 42 are provided for the purpose of wrapping it connecting wire thereto. Variations in such external connecting means are obviously feasible as, for example, soldered connections may be made to the tabs 42, or else the tabs may be formed as plug pins for easy insertion into a socket.
The reed and support arm contacts, a major portion of the reed and the support arms, and the pole member 18 are sealed within the enclosure 24 which is preferably hermetically sealed after being evacuated, or else, backfilled with an inert gas through hollow support tube 36 and ports 44 in the wall of the tube. Sealing is performed by a pinched seal 46. A glass seal can also be used. After sealing, a cap member 48 is inserted over the seal to protect it from subsequent breakage. The cap can also function as a guide for insertion of the relay into the socket if a plug pin structure is used for tabs 42.
The upper end of core 32 is supported via nut 50 screwed upon a threaded extension 52 of the core until it fastens down upon an annular support plate 54 extending across the top of relay shell 56. The shell 56 is preferably made of highly permeable magnetic metal.
The sealed contact enclosure 24 within the external relay shell 56 may take various forms. In the embodiment shown in FIGURE 1 it takes the form of two spaced disks; one of which may be an inner shouldered portion of header 40. The other disk acts as an intermediate bulkhead 58. A tubular sleeve 60, which may be formed of metal, glass, plastic or other suitable material, joins the header and the bulkhead to form the cylindrical enclosure. Fillets 62 of sealer at the juncture of the sleeve and the two disk shaped members insure against leakage. Additional sealer may be used; such as at 64 to further insure a hermetic seal.
In the structure just described, it will be noted that coil 22 is separate from the contacts 12, 14, 16 and 17. Such a separation prevents the contacts from being exposed to the gases which normally exude from the coil, for these gasses are frequently corrosive in nature.
Considerable freedom exists in the selection of workable materials for construction of the relay. As examples, the header 40 and bulkhead 58 may be made of ceramic or a suitable plastic material. Sleeve 60 may be made of glass, plastic, or even of brass or iron. The magnetic elements, such as core 32, pole member 18, and reeds 20 may be chosen from many possible ferromagnetic materials, but preferably ones with a high saturation fiux value should be used; such as, iron or the silicon-iron alloys. The support arms 26 and 28 should be chosen from material with suitable spring properties, such as Phosphor bronze or beryllium copper having suitably low electrical resistivity, and which preferably can be plated with suitable precious metals such as gold for further resistance to corrosion. The contacts 12 to 17 should preferably be made of precious metal, although tungsten or molybdenum alloys may be employed for resistance to arcing and pitting.
Appropriate means, such as spot welding, brazing or soldering are employed for connecting the various tabs or conductor strips to the wires 38 or to the reeds and/ or support arms, if they are formed as separate elements.
The magnetic flux that flows as a result of energizing the coil 22 is believed to follow the path generally indicated by the lines 65. As seen, each path includes the interior of the core 32, annular support plate 54, relay shell 56, open area 66, the magnetic reed 20, the core member 18, and then back to the interior of core 32. Obviously a multiplicity of other similar flux paths exists through each of the magnetic reeds 20, but for simplification, these are not all shown in the drawing.
As to the energizing force or current necessary, obviously the intensity of the magnetic flux increases with increasing current to the coil 22. Thus, the reed 20 is more firmly and sharply attracted toward the pole member 18,. at higher currents. Generally, contact pressures of 4 to grams is believed suflicient to insure efiicient conduction through the contacts. Hence, a current is selected which, through the coil, generates this desired range of contact pressures. The relay response to application of current is generally 4 milliseconds or less.
Referring now to FIGURE 4, there is shown a perspective view of the reed and support arm contacts. It will be noted that the reed bears up against the spacer disk but never touches the rnagnetizable pole member 18. This prevents short circuiting of the reeds 20 through the metallic pole piece 18. Spaced on each side of the reed are support arms 26 and 28, bearing contacts 12 and 14.
Now referring to FIGURES 5 and 6, it will be seen that as the reed 20 travels from left to right, its contact 16 will slide slightly upwardly over the surface of contact 14 on support arm 28. When reed contact 17 touches contact 12, it slides downwardly over the surface of contact 12 on support arm 26. Such sliding break and make contact action results from the biasing of support arms 26 and 28 toward the reed. (See FIGURE 1.) Thus, a relay is provided wherein wiping action at the contacts occurs during each energizati-on. Such wiping contact action is superior to static contact engagement, present in prior art reed relays, as it assures cleaner and more positive contact at lower contact pressures.
The relay can obviously be designed for four possible actions, to wit (1) make, (2) break, (3) break before make, and (4) make before break. With respect to a break before make operation, it should be evident from FIGURES 5 and 6 that contact is broken between contacts 14 and 16 before contact is made between contacts 17 and 12 by the simple positioning of the reed with respect to the support arms and the biased condition of the latter arm. This permits a frequently desirable operating sequence wherein one circuit must be broken before another is made. The in-between time period can be fairly well regulated by appropriate control over the amount of current supplied to coil 22.
It should also be evident from FIGURES 4, 5 and 6, that the reed-support arm structure lends itself very well to relays having both normally open and normally closed contacts, without the need for permanent magnetic biasing. By the mere mechanical biasing or positioning of the support arms relative to the reeds, some contacts may be normally open or normally closed.
It should also be evident from FIGURE 2, that the array positioning of reed-support arms about the pole member 18 effects improved magnetic efiiciency whereby lower coil power can be utilized to operate the entire relay. There is no large core or armature to be moved. The only movement needed is that of the leaf-thin reeds.
The structure also permits positive adjustment of the contacts prior to hermetic sealing. This has never heretofore been possible in reed relay devices, as indicated above.
Obviously, variations in over-all structure are also conceivable. The core and coil could be reversed in location with the sealed contacts located at the upper portion of the shell. Or also the bulkhead could be used as a support for the base of the reeds and support arms. Indeed, the core and coil could be located centrally of the reed-support arm array with a concentric annular wall enclosure about said array. In all instances, the plug pins could be made to extend through either end of the relay. In fact, two or more arrays of reeds and associated support arms could be used with one coil using a double pole member. Many other structural variations are obviously possible within the scope of the invention.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the constructions set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.
Having described my invention, what I claim as new and desire to secure by Letters Patent is:
1. A multi-polar transfer relay comprising, in combination, an annular rnagnetizable pole member presenting a series of relatively small area pole faces spaced circumferentially therearound, a coil and magnetic core associated therewith for magnetizing said pole member, an array of magnetic-responsive contact-carrying reeds spaced circumferentially around said pole member with one side of each reed facing a respective one of said pole faces to define a relatively small area air gap therebetween, at least one contact-carrying support arm associated with and adjacent to each of said reeds whereby the contacts of each may open and close with respect to each other, magnetic flux conductor means presenting a surface of relatively large area facing an opposite side of each reed to define a relatively large air gap therebetween, said reeds being mounted for movement toward or away from said pole member and said flux conductor means being in magnetic communication with said core, whereby upon energization of said coil flux flows along a series of closed paths sequentially including, for each reed, said pole member, the related small area air gap, said reed, the related large area air gap, said flux conductor means, said core, and said pole member again, and said reeds are drawn toward said pole member to perform switching operations with respect to external electrical circuits including said reeds.
2. A multi-polar transfer relay according to claim 1, (A) said magnetic flux conductor means being constituted by an external shell of highly permeable magnetic metal fitting over and enclosing the pole member, coil, core, reed, and support arms.
3. A multi-contact high speed electrical switching device comprising, in combination, a plurality of elongated thin flexible reed members of ferromagnetic metal, means insulatingly supporting said reeds in a substantially cylindrical array about a central axis, a plurality of flexible spring support arm members of non-magnetic metal insulatingly mounted adjacent to said magnetic reeds in a substantially concentric cylindrical array about said common central axis, electrical contacts on adjacent surfaces of said reeds and support arm members at the ends thereof opposite said supporting means, a magnet coil wound upon a core of highly permeable magnetic material and located upon said common axis, an annular magnetic pole piece mounted upon said magnet core concentric with said common axis and positioned between the free ends of said magnetic reeds, insulating material adjacent said pole piece to prevent conductive engagement between said magnetic reeds and said pole piece, an exterior shell of magnetically permeable metal surrounding said magnet coil and extending substantially concentrically about said array of magnetic reeds and spring members to said insulating supporting means to enclose all the elements of said switching device; and means extending externally of said enclosing shell for making electrical connections with said magnet coil, said reeds and said spring members, whereby upon alternate energization and de-energization of said coil said magnetic reeds are alternately moved toward and away from said pole piece to alternately make and break conductive engagement with said contacts.
4. A multi-contact high speed electrical switching device comprising, in combination, a plurality of elongated thin flexible reed members of ferromagnetic metal, means insulatingly supporting said reeds in a substantially cylindrieal array about a central axis, a plurality of flexible spring support arm members of non-magnetic metal insulatingly mounted adjacent to said magnetic reeds in a substantially concentric cylindrical array about said common central axis, electrical contacts on adjacent surfaces of said reeds and support arm members at the ends thereof opposite said supporting means, a magnet coil wound upon a core of highly permeable magnetic material and located upon said common axis, an annular magnetic pole piece mounted upon said magnet core concentric with said common axis and positioned between the free ends of said magnetic reeds, insulating material adjacent said pole piece to prevent conductive engagement between said magnetic reeds and said pole piece, and enclosure about said contact ends of said reeds and said support arms and said magnetic pole piece to isolate said elements from said coil whereby corrosive atmospheres are excluded therefrom, an exterior shell of magnetically permeable metal surrounding said magnet coil and extending substantially concentrically about said array of magnetic reeds and spring members to said insulating supporting means to enclose all the elements of said switching device; and means extending externally of said enclosing shell for making electrical connections with said magnet coil, said reeds and said spring members, whereby upon alternate energization and de-energization of said coil said magnetic reeds are alternately moved toward and away from said pole piece to alternately make and break conductive engagement with said contacts.
5. An electromagnetic circuit control device compris- (A) a contact-carrying reed of magnetic material,
(B) an electromagnet having a pole member presenting a pole surface of relatively small area facing one side of said reed, whereby to define a relatively small area air gap between said pole surface and said reed,
(C) and a magnetic flux conductor presenting a surface of relatively large area facing an oppoiste side of said reed, whereby to define a relatively large area air gap between said conductor and said reed,
(D) said reed being mounted for movement toward or away from said pole surface and said conductor being in magnetic communication with said pole member, whereby upon energization of said magnet, flux flows along a closed path sequentially including said pole member, said small area air gap, said reed, said large area air gap, said conductor and said pole member again and said reed is drawn toward said pole member to perform a siwtching operation with respect to an external electrical circuit including said reed.
6. An electromagnetic circuit control device comprising (A) a sealed enclosure,
(B) an electromagnet having a coil outside of said enclosure and a fixed central core, said core including a portion extending beyond said coil and passing through a wall of said enclosure to present a pole member within said enclosure,
(C) a contact-carrying reed within said enclosure,
(D) said pole member presenting within said enclosure a pole surface of relatively small area facing one side of said reed, whereby to define a relatively small area air gap between said pole surface and said reed,
(E) and an external shell of magnetic material enclosing said coil and surrounding said enclosure and presenting an interior wall surface of relatively large area facing an opposite side of said reed, whereby to define a relatively large area air gap between said shell and said reed,
(F) said reed being mounted for movement toward or away from said pole surface and said shell being in magnetic communication with said core so that upon energization of said coil flux flows along a closed path sequentially including said core, said pole member, said first air gap, said reed, said second air gap, said shell and said core again and said reed is drawn toward said pole member to perform a switching operation with respect to an external electrical circuit including said reed.
References Cited by the Examiner UNITED STATES PATENTS 1,510,341 9/24 Proctor 200-37 1,876,295 9/32 Hofgaard 200103 2,066,894 1/37 McIlVaine 20087 2,166,091 7/39 Field 20087 2,668,207 2/54 Bengtsson 200103 2,767,356 10/56 Olsson 200103 2,933,572 4/60 Howell et al 200-87 3,024,329 3/62 Johnson 20087 BERNARD A. GILHEANY, Primary Examiner.
MAX L. LEVY, ROBERT K. SCI-IAEFER, Examiners.