FLOW HOLE AND FLOW PROJECTION

Abstract: An electromagnetic relay includes a base, a bobbin with a core and at least one winding about the core, a pair of pole pieces extending perpendicularly from the ends of the core, an elongate armature movable with respect to a movable contact, a permanent magnet coupled magnetically between the core and armature and at least one stationary contact. The bobbin further comprises a set of end flanges adjacent the pole pieces, with a means for engaging the end flanges with the pole pieces. The base is provided with a hole therein for inserting an epoxy to bond the bobbin to the base. The cross-sectional area of the core is non-uniform to engage a pair of pole pieces. A bore within the bobbin has a non-uniform cross-sectional area. A bobbin is also provided with depressions at various locations of the flanges and with terminal wires molded within the flanges.

Description: FLOW HOLE AND FLOW PROJECTION BACKGROUND OF THE INVENTION 1. Technical Field of the Invention The present invention relates to an electromagnetic relay featuring structure and methods which engage various components of the relay during assembly and operation. 2. Description of the Related Art Electromagnetic relays are known and widely used throughout the electronics industry. Electromagnetic relays generally include a bobbin, a coil wound thereon, a core, a permanent magnet, an armature, a movable contact and at least one stationary contact. These components are assembled to form an electromagnet block. The electromagnet block, together with the remaining components, are mounted on a base. The base also provides a receptacle for electrically connecting terminals from the contacts and electromagnet block to control and load circuits. A cover is typically placed over the relay, engageable with the base, to form a closed casing. To function properly, the components of the electromagnetic relay must be assembled and maintained to precise tolerances. Unfortunately, working environments for many electromagnetic relays are not predisposed to maintaining precise tolerances (e.g., automobiles, factories, manufacturing and power plants, etc.). Environmental conditions such as temperature differentials, vibration, moisture and dust often cause movement between the several components of a relay, thereby altering the required tolerances and detracting from the relay's performance. For example, the distance between the movable contact and the stationary contact, i.e., the contact gap; the load placed on the stationary contact by the movable contact, i.e., the overtravel ; and the distance through which the armature moves to contact the electromagnet, i.e., the armature gap; must all be set and maintained within precise limits. Each of these design parameters is interrelated due to the movement of the various components. Thus, undesired movement often eventually result in failures of the relays and their related electric circuits. Therefore, to resolve the long-standing problem of the detrimental effects on relays and their associated electric circuits, a need exists for electromagnetic relays that provide structure and are assembled in such a fashion as to withstand the adversities of harsh operating environments while still maintaining precise tolerances. Structural enhancements to various components of the electromagnetic relay are provided herein which will eliminate' movement between the components and therefore provide a more reliable relay. SUMMARY OF THE INVENTION The principal objective of this invention is to provide an electromagnetic relay capable of withstanding harsh operating environments while maintaining precise tolerances between its several components. The principal objective is accomplished by the various enhancements to the structure of an electromagnetic relay as disclosed and recited herein. The present invention provides an electromagnetic relay comprising a base and an electromagnet block on the base comprising a bobbin having a core, at least one winding about the core and a pair of plate-like pole pieces extending perpendicularly from the ends of the core. The bobbin also has a pair of end flanges each adjacent one of the pole pieces. A means for engaging the end flanges with the pole pieces is provided. In a preferred embodiment, a projection, or the like, extends perpendicularly from each end flange to insertably mate with a dimple or the like in each pole piece. This means for engaging the end flanges with the pole pieces precludes the possibility that the components will be assembled backwards. The present invention provides further advantageous structural features of the base and bobbin of an electromagnetic relay. The features include a base having a hole therein and a bobbin having a projection extending perpendicularly therefrom, insertably mating with the hole in the base. With the bobbin assembled to the base, an epoxy may be inserted into the hole. The preferred embodiment is a conical projection extending from the bobbin. The pointed distal end of the conical projection will pierce the meniscus of the epoxy within the hole and cause the epoxy to flow down around the projection extending from the bobbin. Furthermore, a cavity is formed between a portion of the bobbin and the base. Epoxy will continue to flow down the length of the projection and fill the cavity. The bobbin will be permanently affixed to the base after the epoxy cures and will, therefore, not move with respect to the base. Another advantageous structural feature is incorporated into the shapes of the bore and core within the bobbin. The present invention discloses and recites a bore having a non-uniform longitudinal cross-sectional area. A plurality of flats are also provided along the length of the bore. The plurality of flats are tapered, conversely corresponding to the non-uniform cross- sectional area longitudinal with the bore to form longitudinal lands defining a uniform cylindrical cross- sectional area for insertably receiving a core with a correspondingly uniform cylindrical cross-sectional area. In one preferred embodiment, the non-uniform cross- sectional area of the bore is conical. The present invention also discloses and recites a cylindrical core having a center portion and two end portions. In a preferred embodiment, the end portions are axially aligned with the center portion and have a diameter smaller than a diameter of the center portion. A stepped change in diameter occurs to define shoulder portions of the core at the points of change. The shoulder portions ensure proper engagement between the core and a pair of pole pieces. More specifically, the preferred embodiment ensures that the pole pieces of the relay are located flush against the end of the electromagnet block thereby minimizing non-working air gaps. The present invention further provides another structural feature in the bobbin of an electromagnetic relay as described above. The feature is directed to a bobbin comprising a pair of end flanges wherein the end flanges have a plurality of depressions therein. In a preferred embodiment, two depressions are provided to ensure that a spacing between load and control circuits is maintained. The present invention provides yet another structural feature in the bobbin of an electromagnetic relay as described above. In a bobbin having a pair of end flanges and a center flange, each of said flanges has a coil terminal wire molded therein. In a preferred embodiment, the winding about the core of the bobbin is routed through a depression in the center flange and connected to each of the coil terminal wires as it is wound about the core. After a permanent connection is made between the winding wire and the coil terminal wires, the terminal wires are formed forward. One advantage of a formed forward connection is strain relief of the wire. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference is made to the following description of an exemplary embodiment thereof, and to the accompanying drawings, wherein: FIG. 1 is an exploded perspective view of an electromagnetic relay constructed in accordance with a preferred embodiment of the present invention; FIG. 2A is an enlarged fragmentary view of an end flange with a projection therefrom; FIG. 2B an enlarged side view of an end flange with a projection therefrom; FIG. 3A is an enlarged fragmentary view of a typical pole piece having a dimple therein; FIG. 3B is an enlarged side view of a typical pole piece having a dimple therein; FIG. 4 is an enlarged fragmentary perspective view of a bobbin having a projection and a base having a hole; FIG. 4A is an enlarged perspective view of a portion of the base defining a hole; FIG. 4B is an enlarged perspective view of a projection on a bobbin; FIG. 5 is an enlarged view of a bobbin having a projection inserted into a base having a hole with epoxy in the hole; FIG. 5A is an enlarged fragmentary view of a bobbin having a projection inserted into a base having a hole with epoxy in the hole; FIG. 6 is an enlarged view of epoxy filling a cavity between a bobbin and a base; FIG. 6A is an enlarged fragmentary view of epoxy filling a cavity between a bobbin and a base; FIG. 7 is a fragmentary top view of a bobbin and coil wound thereon; FIG. 8 is a fragmentary side view of a bobbin and a coil wound thereon; FIG. 9 is a fragmentary cross-sectional view of a bobbin and coil taken along line 9-9 of FIG. 8; FIG. 10 is a fragmentary cross-sectional view of a bobbin having a bore of conical shape; and FIG. 11 is a fragmentary perspective view of a pair of fixed terminals having interference projections. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown an electromagnetic relay of the present invention illustrated generally at 8. The relay comprises a base 10 which defines a main or bottom plane for the relay. A pair of stationary or fixed contact terminals 12 and 14 are fastened in the base 10; these fixed terminals 12 and 14 are disposed perpendicular to the plane of base 10 and are provided with fixed contacts 16 and 18. The fixed terminals 12 and 14 are inserted into slots 20 in the base 10 and are fixed by caulking, epoxy or by any other suitable sealant or method. Further, coil terminals 22 and 24 and a common coil terminal 26 are fastened in the base 10 in a similar manner. A pair of suppression resistors 28 or other components may be arranged on the base 10 and connected to the coil terminals 22, 24 and 26. An electromagnet block 30 arranged on the base 10 comprises a bobbin 32 with a pair of coils 34 and 36 wound thereon between end flanges 38 and 40 and a center flange 42. The end flanges 38 and 40 are provided with depressions 37. An iron core 44 of cylindrical shape is inserted axially into the bobbin 32 and coils 34 and 36 and is coupled at its ends to a pair of plate-like pole pieces 46 and 48 which are provided with dimples 50 and 52 which mate with projections 54 and 56 on end flanges 38 and 40 and are provided with through holes 58 and 60, respectively, corresponding in diameter to the core 44. In a preferred embodiment, core 44 comprises a center portion 45 and two end portions 47 and 49. End portions 47 and 49 are axially aligned with center portion 45. End portions 47 and 49 have a diameter less than a diameter of center portion 45. The change in diameter is stepped thereby forming shoulders at the point of change. In a preferred embodiment, holes 58 and 60 in pole pieces 46 and 48 have a diameter corresponding to the diameter of end portions 47 and 49. FIGS. 2A and 2B illustrate a detail of a preferred embodiment of projections 54 and 56 on end flanges 38 and 40. FIGS. 3A and 3B illustrate a detail of a preferred embodiment of dimples 50 and 52 on pole pieces 46 and 48. A plate-like elongate permanent magnet 62 is disposed along one lateral side of the bobbin 32 in a plane perpendicular to the plane of base 10 and bridging the end flanges 38 and 40 as well as the pole pieces 46 and 48. The permanent magnet 62 is magnetized in a three-pole manner so as to have the same magnetic poles (south poles S) at both ends and the opposite pole (north pole N) in its center. An elongate, plate-like armature 64 which is slightly bent into a V-shape, is balanced on the center pole N of the permanent magnet 62 so as to form air gaps between its end portions and either one of the pole pieces 46 and 48. Either end of the armature 64 is divided into a pair of legs 66 and 68, by means of recesses 72 and 74, respectively. A strip-like movable contact spring 76 is fastened to the central part of the armature 64 by means of rivets 78 or the like. A strip-like movable first braid 80 is engageable with contact spring 76. A pair of movable contacts 82 and 84 are fixed to the ends of first braid 80 by welding or any other suitable method. A second braid 86 is fixed on a first end to first braid 80 intermediate movable contacts 82 and 84. The second end of second braid 86 is fixed to a movable terminal 88, to carry the load current between the movable contacts 82 and 84 and movable terminal 88. Movable terminal 88 is fastened in base 10 in a similar manner as terminals 12 and 14. When the relay parts are assembled along the broken lines shown in FIG. 1, winding terminals 92, 94 and 96, which are anchored in the bobbin flanges 38, 40 and 42, are connected by welding or any other suitable method to the coil terminals 22, 24 and 26. In a preferred embodiment, depressions 37 provide increased spacing between a pair of plate-like pole pieces 46 and 48 and winding terminals 92 and 94. An enclosure 98 may be put over the assembled relay to form a closed casing together with the base 10. FIGS. 4, 4A and 4B depict detail views of a base 100 defining a hole 102 and a bobbin 104 comprising a projection 106 extending perpendicularly from a portion of bobbin 104 whereby projection 106 is insertable into hole 102 when base 100 and bobbin 104 are assembled along the broken lines shown therein. Projection 106 is shown in a preferred conical configuration. FIGS. 5 and 5A depict a bobbin 104 comprising a projection 106 assembled with a base 100 having a hole 102 wherein the projection 106 is inserted into the hole 102. FIG. 5A shows an uncured epoxy 108 within hole 102. As shown, a distal pointed end of projection 106 penetrates a meniscus of the uncured epoxy 108 thereby causing the uncured epoxy to flow along the edges of projection 106. As depicted in FIGS. 6 and 6A, a cavity 110 is defined between bobbin 104 and base 100. Uncured epoxy 108 flows into cavity 110 from hole 102 as the epoxy flows along the edges of projection 106. The epoxy within cavity 110 will affix bobbin 104 to base 100 as it cures. Referring now to FIGS. 7, 8 and 9, there is shown a bobbin of an electromagnetic relay of the present invention. The bobbin 112 comprises a pair of coils 114 and 116 wound thereon between end flanges 118 and 120 and a center flange 122. End flanges 118 and 120 and center flange 122 each have coil terminal wires 124, 126 and 128 molded therein. A start lead 130 of coil 114 is connected to terminal wire 124 by soldering or any other suitable means and is wound on bobbin 112. A finish lead 132 of coil 114 is routed through a depression in center flange 122 and connected to coil terminal wire 128 in substantially the same manner. A start lead 134 of coil 116 is also connected to coil terminal 128 in substantially the same manner and is then wound on bobbin 112. A finish lead 136 of coil 116 is connected to coil terminal wire 126 in substantially the same manner as the above connections. In a preferred embodiment, coil terminal wire 128, finish lead 132 and start lead 134 are formed forward to strain relieve the wires. FIG. 10 illustrates a cross-sectional view of a preferred embodiment of a bobbin 138 having a bore 140, the bore 140 having a conical shape. FIG. 11 illustrates a perspective view of a preferred embodiment of a pair of fixed terminals 142 and 144 having interference projections 146 thereon. Interference projections 146 ensure an interference fit as terminals 142 and 144 are insertably engaged with a base. It will be understood that the embodiments disclosed herein are merely exemplary and that one skilled in the art can make many variations and modifications to the disclosed embodiments without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined by the appended claims.

Claims: WHAT IS CLAIMED IS; 1. An electromagnetic relay comprising: a base defining a bottom plane; an electromagnet block on the base having a core, means for exciting a coil including a bobbin and at least one winding about the core, a pair of pole pieces extending perpendicularly from the ends of said core, said bobbin having a pair of end flanges each adjacent one of said pole pieces, and a means for engaging said end flanges with said pole pieces; an elongate armature pivotally supported at its central portion to be movable about a center pivot axis for angular movement between two contact operating positions, either end portion of the armature on either side of the pivot axis defining an air gap with one of said pole pieces; a permanent magnet coupled magnetically between said core and said armature so as to induce the same magnetic poles in both said pole pieces and to provide an opposite pole in closely adjacent relationship to said central portion of the armature; at least one movable contact spring fixedly connected to the armature at a portion intermediate the ends thereof and being formed with contact arms in the vicinity of either armature end portion, said contact arms carrying movable contacts to be moved according to the armature movement in and out of contact with corresponding fixed contacts mounted on said base; and a conductor connecting said contact arms with a movable contact terminal mounted on said base. 2. A relay as recited in Claim 1, wherein said end flanges have a projection extending perpendicularly therefrom and said pole pieces have a dimple, said projection insertably mating with said dimple. 3. A relay as recited in Claim 1, wherein said core is cylindrical, said core comprising a center portion and two end portions, said end portions having a diameter less than a diameter of said center portion. 4. A relay as recited in Claim 3, wherein each of said pole pieces has a hole therein corresponding to a diameter of said two end portions of said core, for insertably receiving said two end portions in said holes in said pole pieces. 5. An electromagnetic relay comprising: a base defining a bottom plane and having a hole therein; an electromagnet block on the base having a core, means for exciting a coil including a bobbin and at least one winding about the core, and a pair of pole pieces extending perpendicularly from the ends of said core; a projection extending perpendicularly from said bobbin insertably mating with said hole in said base; an elongate armature pivotally supported at its central portion to be movable about a center pivot axis for angular movement between two contact operating positions, either end portion of the armature on either side of the pivot axis defining an air gap with one of said pole pieces; a permanent magnet coupled magnetically between said core and said armature so as to induce the same magnetic poles in both said pole pieces and to provide an opposite pole in closely adjacent relationship to said central portion of the armature; at least one movable contact spring fixedly connected to the armature at a portion intermediate the ends thereof and being formed with contact arms in the vicinity of either armature end portion, said contact arms carrying movable contacts to be moved according to the armature movement in and out of contact with corresponding fixed contacts mounted on said base; and a conductor connecting said contact arms with a movable contact terminal mounted on said base. 6. A relay as recited in Claim 5, wherein said projection is conical in shape, a distal pointed end of said projection is insertably aligned in said hole in said base. 7. A relay as recited in Claim 6, wherein said hole and said projection define a means for affixing said bobbin to said base by inserting an epoxy into said hole, said conical projection penetrating a meniscus in said epoxy causing said epoxy to flow around said projection to fill a void formed between said conical projection and a portion of the base forming a perimeter around said hole. 8. A relay as recited in Claim 7, wherein a cavity is formed between said bobbin and said base wherein said cavity is filled with said epoxy. 9. An electromagnetic relay comprising: at least one stationary contact mounted on a base and a movable contact mounted on the base, the movable contact movable with respect to the at least one stationary contact; an electromagnet block mounted on the base having a core, a bobbin having a bore and at least one winding about said bore, said core being insertable within said bore, said bore having a non-uniform cross-sectional area along a length of said bore. 10. An electromagnetic relay as recited in Claim 9, wherein said non-uniform cross-sectional area of said bore is conical. 11. An electromagnetic relay as recited in Claim 9, wherein a plurality of flat members form a plurality of longitudinal lands along an axis of said bore. 12. An electromagnetic relay as recited in Claim 11, wherein said plurality of flat members have a non- uniform cross-sectional area conversely corresponding to said non-uniform cross-sectional area of said bore, along a longitudinal length of said bore, forming longitudinal lands defining a uniform cylindrical cross-sectional area for insertably receiving a core having a correspondingly uniform cylindrical cross-sectional area. 13. An electromagnetic relay comprising: a base defining a bottom plane; an electromagnet block on the base having a core, means for exciting a coil including a bobbin and at least one winding about the core, a pair of pole pieces extending perpendicularly from the ends of said core, said bobbin having a pair of end flanges, said end flanges including a means for increasing a spacing between said pair of pole pieces and a terminal of said at least one winding; an elongate armature pivotally supported at its central portion to be movable about a center pivot axis for angular movement between two contact operating positions, either end portion of the armature on either side of the pivot axis defining an air gap with one of said pole pieces; a permanent magnet coupled magnetically between said core and said armature so as to induce the same magnetic poles in both said pole pieces and to provide an opposite pole in closely adjacent relationship to said central portion of the armature; at least one movable contact spring fixedly connected to the armature at a portion intermediate the ends thereof and being formed with contact arms in the vicinity of either armature end portion, said contact arms carrying movable contacts to be moved according to the armature movement in and out of contact with corresponding fixed contacts mounted on said base; and a conductor connecting said contact arms with a movable contact terminal mounted on said base. 14. An electromagnetic relay as recited in Claim 13 , wherein said means for increasing a spacing between a load circuit and a control circuit comprises a pair of end flanges having a plurality of depressions. 15. An electromagnetic relay comprising: a base defining a bottom plane; an electromagnet block on the base having a core, means for exiting a coil including a bobbin and at least one winding about the core, a pair of pole pieces extending perpendicularly from the ends of said core, said bobbin having a pair of end flanges adjacent each of said pair of pole pieces and a center flange intermediate said pair of end flanges, said pair of end flanges and said center flange each having a coil terminal wire molded therein; an elongate armature pivotally supported at its central portion to be movable about a center pivot axis for angular movement between two contact operating positions, either end portion of the armature on either side of the pivot axis defining an air gap with one of said pole pieces; a permanent magnet coupled magnetically between said core and said armature so as to induce the same magnetic poles in both said pole pieces and to provide an opposite pole in closely adjacent relationship to said central portion of the armature; at least one movable contact spring fixedly connected to the armature at a portion intermediate the ends thereof and being formed with contact arms in the vicinity of either armature end portion, said contact arms carrying movable contacts to be moved according to the armature movement in and out of contact with corresponding fixed contacts mounted on said base; and a conductor connecting said contact arms with a movable contact terminal mounted on said base. 16. A relay as recited in Claim 15, wherein said at least one winding about the core is connected to said coil terminal wires molded in said pair of end flanges and said center flange. 17. A relay as recited in Claim 16, wherein said center flange has a depression. 18. A relay as recited in Claim 17, wherein said at least one winding about the core is routed through said depression in said center flange. 19. A relay as recited in Claim 18 , wherein said terminal wires are formed forward after connection to said at least one winding. 20. A method of affixing an electromagnetic block to a base of a relay, comprising: inserting a projection of a bobbin in a hole of a base ; pouring an epoxy into said hole of said base; causing the epoxy to flow around said projection; filling a void formed between said projection and a portion of the base forming a perimeter around said hole; and heating said electromagnetic block and base in an oven and curing said epoxy. 21. The method as recited in Claim 20, wherein penetrating a meniscus in said epoxy with a distal pointed end of said projection causes said epoxy to flow around said projection. 22. An electromagnetic relay having an electromagnetic block affixed to a base in accordance with the method of Claim 20.

Inventors: HALTER JAMES MATTHEW, HALTER, JAMES, MATTHEW
Applicants: SIEMENS ELECTROMECH COMPONENTS, SIEMENS ELECTROMECHANICAL COMPONENTS, INC.
Application year: 1998
Main classification: H01H51
IPC codes: H01H50, H01H51