US 3539956 A
Description (OCR text may contain errors)
NOV. 10, 1970 c, ANDERSEN ETAL 3,539,956
' LOW PROFILE RELAY Filed July 9, 1968 United States Patent 3,539,956 LOW PROFILE RELAY Clifford H. Andersen, Niles, and Harry Chanowitz, Skokie, Ill., assignors to C. P. Clare Company, Chicago, Ill., a corporation of Delaware Filed July 9, 1968, Ser. No. 743,528 Int. Cl. H01h 51/28 U.S. Cl. 335-154 6 Claims ABSTRACT OF THE DISCLOSURE A low profile relay using a sealed magnetic switch disposed in the axial opening of a coil-bobbin assembly. The switch housing is oval in section with the major axis of the section extending parallel to the flat, overlapping ends of the reeds. The center section of the bobbin comprises two walls of a height generally the same as the minor axis of the oval housing spaced from each other generally the length of the major axis so that the coil lies against the elongated walls of the switch housing. Thus, the height of the switch and coil-bobbin assembly is reduced and the coil is moved closer to the operating gap.
This invention relates to a relay assembly and, more particularly, to a low profile relay using one or more sealed magnetic switches.
Although relays including an assembly of one or more sealed magnetic switches and an operating winding have been known and used for a substantial period of time, the increasing trend toward miniaturization of electronic and electrical components and assemblies in virtually all fields has made it necessary for relay manufactures to attempt corresponding reductions in the size of switching assemblies. As an example, one common application for relays using sealed magnetic switches is as a module mounted on a printed circuit board. The height of the module above the board is the most critical dimension to be considered in size reduction because it determines the maximum board-to-board spacing and the ultimate component density.
This dimension includes, in a sealed switch module, such factors as switch diameter, the thickness of the winding, the thickness of the relay cover and base, and the thickness of any potting or insulating material required. The two largest of these factors are the coil bobbin and switch diameters. An attempt has been made to reduce the coil bobbin diameter by doing away with the coil bobbin and using filled or self-supporting coils. This has not been particularly satisfactory because the weight of the coil becomes somewhat excessive and the amount of filling material frequently prevents the attainment of any appreciable reduction in coil diameter. In addition, the mean diameter of the coil is a significant factor in the magnetic efiiciency of the relay because the switch is most efficiently operated when the field is disposed as closely as possible to the switch gap. The use of filled coils also suffers from the disadvantage that the glass envelope of the switch is sometimes subjected to the weight of the coil.
Another approach that has been tried is to reduce the thickness of the bobbin wall to a minimum, and it appears as if a practical minimum wall thickness is .012.015" with present materials and molding techniques. Further, the inside diameter of the bobbin opening in which the glass switch is to be mounted tends to decrease after molding and winding a coil thereon because of cold flow of the bobbin material. The final inside diameter is a function of the bobbin material, the diameter of the wire used in winding the coil, the number of turns in the coil, and the winding tension. Since the final bobbin opening remaining after some period of storage must be such as to accept the switch, the usual practice is to allow appreciable clearance which increases the height of the module. This clearance is also objectionable because the apparent mean diameter of the coil, as seen by the switch gap, is larger.
Accordingly, one object of the persent invention is to provide a low profile relay using a sealed magnetic switch.
Another object is to provide a new and improved relay in which the size is reduced and the magnetic efficiency of the relay is increased by using a transversely elongated sealed switch housing and removing the bobbin material from between the elongated sides of the housing and the operating coil.
A further object is to provide a new and improved relay using a sealed magnetic switch with an oval housing and a bobbin in which the inner turns of the coil are permitted to engage the switch housing so as to reduce the height of the switch and increase its magnetic efiiciency In accordance with these and many other objects. an embodiment of the invention comprises a sealed switch assembly using one or more sealed magnetic switches located in the axial opening of a coil bobbin on which an operating winding or coil is disposed. The sealed magnetic switch units are quite similar to those that are well known in the art and comprise an elongated glass housing in the opposite ends of which magnetic reeds are sealed with their inner ends normally in a spaced and overlapped relationship to define an operating gap. However, in accordance with the present invention, the elongated glass housing is made elliptical or oval in section with the major axis of the ellipse or oval extending parallel to the enlarged or flattened end portions of the reeds.
In this manner, the portions of the magnetic reeds forming the operating gap are disposed closer to the outside wall of the adjacent portion of the housing.
The coil bobbin includes a pair of end walls joined by a central portion or sleeve formed of two spaced walls of a height approximating the minor axis of the oval section of the glass housing and spaced from each other approximately the length of the major axis of the oval or elliptical section of the housing. Thus, when a coil is wound on the bobbin, the spaced walls take up the tension and an appreciable portion of the weight of the coil, yet permit the inner turns of the winding to be in direct engagement with the outer wall of the oval housing along the elongated sides thereof. By disposing the resulting relay structure with the major axis of the oval section extending parallel to the plane of the printed circuit board, the overall height of the module is reduced. Further, since the gap defining portions of the magnetic reeds are disposed closer to the outer wall of the glass housing because of its elliptical or oval configuration and because the inner turns of the winding are disposed immediately adjacent the elongated outer walls of the housing, the mean diameter of the coil as seen by the operating gap is substantially reduced with the result that the magnetic efiiciency of the relay is improved, thereby permitting a smaller operating coil or winding to be used with an attendant reduction in the projection of the relay module above the surface of the printed circuit panel.
Many other objects and advantages of the present invention will become apparent from considering the following detailed description in conjunction with the drawings in which:
FIG. 1 is a side elevational view in partial section of a relay embodying the present invention;
FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 1;
FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 1; and
FIG. 4 is an enlarged perspective view of a coil bobbin used in the relay.
Referring now more specifically to FIG. 1 of the drawings, therein is illustrated a relay which embodies the present invention and which is formed by a sealed. magnetic switch 12 disposed within the axial opening on a coil bobbin indicated generally as 1-4 on which is disposed an operating winding or coil 16. The configurations of the components 12, 14, and 16 are such that the magnetic efiiciency of the switch 10 is improved, and this switch requires a minimum or greatly reduced standoif height from a supporting panel or printed circuit board.
The sealed magnetic switch unit 12 is in most respects similar to sealed magnetic or reed switch units that are well known in the art in including an elongated glass or insulating housing 18 in the opposite ends of which a pair of magnetic reeds 20 are sealed with a portion of each of these reeds disposed beyond the ends of the housing 18 to provide a means for extending electrical connections. The inner ends of the reeds 20 are provided with transversely elongated or flattened portions 20A normally disposed in a spaced but overlapping relation to define an operating gap. The sealed switch unit 12, however, differs from those known before by providing a glass housing 18 that is generally elliptical or oval in its configuration (FIG. 2)' or section (FIG. 3). The reeds 20 and the glass housing 18 are so arranged that the transversely elongated or flattened portions 20A of the reeds extend generally parallel to the major axis of the oval or elliptical section of the glass housing 18 (FIG. 3). Thus, the operating gap between the overlapped ends 20A is more closely disposed adjacent the outer surface of the housing 18 along its elongated sides than would be the case with the usual glass housing that is generally circular in section.
The bobbin construction 14 can be formed integrally or of several parts and of a plastic material such as nylon or any other suitable nonmagnetic material. In general, the bobbin structure 14 includes a pair of spaced. end walls 22 and 24 joined by a central portion indicated generally as 26. The structures 22, 24, and 26 define an axially extending opening indicated generally as 28 in which the sealed switch 12 is received. The central portion 26 is defined by a pair of spaced walls 30 and 32 which are spaced from each other a distance generally equal to the length of the major axis of the oval section of the glass housing 18 to define an open gap or slot 33 therebetween (FIG. 3). The walls 30 and 32 have a height measured in a direction parallel to the minor axis of the oval section of the housing 18 that is substantially equal to the length of the minor axis (FIG. 3). The outer corners of the two walls 30 and 32 are provided with a radius to avoid presenting a sharp edge to the inner turns of the coil 16, and the central portions of the inner surfaces of these walls are provided with arcuate recesses to accommodate or receive the rounded edges of the housing 18.
The coil 16 is wound on the bobbin structure 14 to be disposed between the end walls 22 and 24 with the inner turns engaging the outer surface of the walls 30 and 32 forming the central portion 26 of the bobbin structure 14. Thus, the bobbin structure 14 provides a winding form which carries the tension and weight of the coil 16 and isolates this weight from the housing 18 of the sealed switch 12. In dependence on the winding tension used and the weight and diameter of the wire used in forming the coil 16, the inner turns may sag slightly into the opening 28 in the open areas between the side walls 30 and 32. When the sealed switch 12 is inserted into the axial opening 28, the elongated walls of the housing 18 displace any sagging portion of the coil 16 so that the coil is in immediate proximity to or engages the transversely elongated side walls of the glass housing 18, thereby to place the coil as close as possible to the overlapped end portions 20A of the magnetic reeds 20 (FIG. 3).
To provide terminals for extending connections to the coil 16, and in some instances, to the reeds 20, the two end walls 22 and 24 are provided with projecting portions 22A, 22B, and 24A, 24B in each of which is formed an arcuate groove or slot 34 (FIGS. 2 and 4). These grooves 34 are used to mount up to four terminals 36 on the relay structure 10, up to two on each of the end walls 22 and 24. Each of the terminals 36 includes an arcuate portion 36A of a configuration corresponding to that of the groove 34, which arcuate portion is pressed into the groove 34 and secured therein. In a preferred embodiment, a heated plate is pressed against the outer surface of the projecting portions 22A, 22B, 24A, and 24B as necessary to warm the plastic material of the bobbin 14 and distort this material into the groove 34 over the arcuate portion 36A of the terminals 36 thereby to stake or secure the terminals in position. The terminals 36 are used to extend electrical connections between terminal pins or external circuits and the coil 16 or the terminal portions of the magnetic reeds 20.
To facilitate the interconnection of the terminals 36 to the start and finish leads of the coil 16, a leg 36B of the terminal 36 extends in the position shown in dashed outline in FIG. 2 when the terminal 36 is mounted on the end wall 22, 24. A start lead 38 for the coil 16 can extend between the walls 30, 32 into the opening 28 and around the projecting portion 22B (FIG. 2) to a point adjacent the leg 36B of the terminal 36. This completely protects this lead and avoids the necessity of molding specially formed openings or recesses in the bobbin structure 14. This lead and the finish lead which is located at the outer surface of the coil 16 adjacent an end wall, such as the wall 24, are then wrapped around the portions of the terminals 36B projecting outwardly beyond the edge of the end walls 22 and 24, and the projecting portions of the legs 36B are then bent rearwardly (FIG. 2) to the position illustrated in solid line in FIG. 1. The adjacent portion of the end walls 22, 24 is provided with a recess 22C or 24C so that the leg 36B does not extend beyond the outline of the end walls. Another leg 36C on the terminal 36 is used to extend the external connection, and although is shown in the drawings as extending generally parallel to the terminal portions of the reeds 20, can also be bent to any suitable position.
The relay 10 can be mounted directly on a printed circuit board by placing the lower edges of the end walls 22, 24 (FIGS. 2 and 3) on the printed circuit board so that the major axis of the oval section of the glass housing 18 extends generally parallel to the board. Suitable terminals on the board or connecting means can be used to mount the relay 10 and to extend electrical connections to the terminals 36 and the magnetic reeds 20. In a preferred embodiment, however, the relay 10 is enclosed within a housing which may be filled with a potting material and perhaps provided with a base carrying terminal connectors which are electrically connected to the terminals 36 and the magnetic reeds 20. In this relay module, the orientation of the relay 10 to the plane of the printed circuit board is the same as that described.
In one such module embodying the relay 10 of the present invention, the finished encapsulated relay has a height of .187 maximum, a height considerably smaller than anything now known. This reduction in height is achieved by the use of the oval glass housing 18 with the major axis of this oval section of the housing extending parallel to'the enlarged portions of the reeds 20 and also to the plane of the printed circuit board. This height reduction is also made possible by the complete removal of the bobbin material along the elongated sides of the oval section of the glass housing 18 to effectively reduce the mean diameter of the coil 16. This increases the magnetic efficiency of the switch and permits the use of a coil 16 smaller than would be possible with the usual circular switch housing and bobbin.
Although the drawing illustrates a relay including only a single sealed switch 12, the bobbin structure 14 can be made with the walls 30 and 32 spaced from each other by a distance that is a whole number multiple of the length of the major axis of the oval section of the glass housing 18 to permit a number of sealed switches 12 to be placed in side-by-side relation within the opening 28. Such a relay would embody the advantages attained in the illustrated construction.
Although the present invention has been described with reference to several illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention.
What is claimed and desired to be secured by Letters Patent of the United States is:
1. A relay comprising a sealed magnetic switch having an elongated insulating housing in which are sealed contacts movable into and out of engagement by a magnetic field, said housing having an elongated cross section with its width measured in a first direction being of a first value that is greater than a second value of its height measured in a second direction generally transverse to the first direction,
a coil bobbin structure having two longitudinally elongated and generally parallel walls forming an elongated opening in which the sealed magnetic switch is disposed, said walls being transversely spaced from each other a distance substantially equal to said first value or a whole number multiple thereof to provide an open gap therebetween, said walls also having a height substantially equal to said second value,
and a coil carried on said bobbin structure and encircling said walls with the inner turns of the coil disposed adjacent the housing in the gap between said walls.
2. The relay set forth in claim 1 including 7 arcuate slots formed on the bobbin structure at the opposite ends thereof each disposed within a plane extending transverse to the direction of elongation of the opening in the bobbin structure,
and terminals including arcuate portions secured in the slots and another portion projecting outwardly beyond the ends of the bobbin structure.
3. An eflicient, low profile relay comprising a coil bobbin having a pair of spaced end walls joined by a center portion, said center portion including a pair of spaced and generally parallel walls of a given height, said end walls and said center portion having an axial opening through the bobbin and said spaced walls defining an open gap therebetween.
a sealed magnetic switch unit disposed within said axial opening, said sealed switch including an elongated and hollow insulating housing that is generally oval in section, the minor axis of said oval being substantially the same as said given height, said sealed switch also including a pair of magnetic elements sealed in the opposite ends of the housing and extending axially into the housing, said magnetic elements having generally fiat end portions spaced from each other in an overlapping but spaced relation with the flat end portions extending generally parallel to the major axis of the oval, and a winding carried on the center portion of the bobbin between the end walls and disposed immediately ad acent the outer wall of the housing in the gap between the spaced walls of the center portion of the bobbin. 4. A relay construction comprising a bobbin structure including spaced end walls connected by a center portion forming an axial openmg, said center portion having at least one slot therein extending substantially from one end wall to the other,
a sealed switch unit disposed in the axial opening, a coil terminal carried on at least one of the end walls, a coil carried on the center portion of the bobbin structure, and a coil lead conected to the coil and extending through said slot and said axial opening to be connected to said coil terminal at a point outside said bobbin structure. 5. The relay set forth in claim 4 in which the end wall includes a recessed area forming an acute angle, said area facing outwardly away from the center portion of the bobbin structure and receiving a correspondingly formed portion of the coil terminal to mount the coil terminal on the end wall. 6. The relay set forth in claim 4 in which said one end wall is generally uniplanar and includes a projecting portion on which said coil terminal is carried, said coil lead extending around the projecting portion to lie in a position spaced inwardly from the outermost part of said one end wall.
References Cited UNITED STATES PATENTS 3,129,311 4/1964 Bergstrasser 335-l54 X 3,263,043 7/1966 McKeon et a1 335-154 3,265,825 8/1966 Barton 335-152 3,434,079 3/1969 Ege 33S151 FOREIGN PATENTS 1,210,474 2/ 1966 Germany.
BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, ]R., Assistant Examiner US. Cl. X.R. 3 -202