US2433703A - Plunger electromagnet - Google Patents

Description

Dec. 30, 1947. E. F. MEKELBURG 2,433,703

PLUNGER ELECTROMAGNET Filed Feb. 5,v 1943 ing membersV L.

Patented Dec. 30, 1947 Earl F. Mekelburg, Wauwatosa,I Wis., assignor to Square D Company, Detroit, .Mich., acorporation of Michigan ApplcationFebruary 3, 1943*Serial No. 474,503`

4Claims.r 1

This invention relates tok an electromagnetic operatori'or an electric:V switch and has for its object the provision of such an operator: which shall include a rectilinearly' movable plunger armature guided at its opposite ends so. as to properly spacey the same from( the. stationary magnetic elements.

Another object of the invention is the; provision of an electromagnetic operator for an electricl switch in which the operator inciudes a plunger armature having'i-ts rinterior end formed in the shape of a'truncated cone Vseating within a complementary recess in a stationary magnetic core member, the diameters ofv the cone and recess being such as to preventA engagement of the sides of the cone and recesswhen the armature plunger is seated.

Other objects and; features of the invention will be readily apparent to those skilled in the art from the specication and appended drawing illustrating certain preferred errrbodimentsy in which:

Figure 1 is a side elevational View of the switch according tothe presentinvention with a portion y Figure 5 is a top plan view of the switch with portions broken away.

The electric switch, as illustrated in the drawings, comprises a base composed of two plate members 2 and 3 formed of insulating material. A, pairl of' conducting connecting members, lY and 5, having contact faces 5l and-1 provided aty the inner ends thereof are disposed at thel underside of the base and haveprojections 6, and 9 thereon adapted to, be received within.openingsy and f2 provided in the insulating plate member 3 to thereby properly locate the connecting members 4, andl ii and to prevent. their turning. out of, position.; The connectingmembers 4 and 5 are rigidly secured to the base i by a pair oi terminal studs i''and' ii, passing through aligned openings .in the cennecting members'and the' insulat 'i 3*, and their cooperating nuts l5 and' i'. A washerr i? is disposed beneath each of the nuts 51 and E161 A second pair of nuts land i9 are-providedon the'studs |f3 and lwhereby^ circuit wires (Snot. shown). maybe secureditothe switch'. A pair'oi. washers 2|l and' 55H (Cl. 17E-341) 2 22v are providedbetween each. pair of nuts l5. and I8, and t6 and I9.

A magnetic plate 23A is carried on topy of. the base l and is secured thereto by rivets 24, one of which is illustrated rin Figure 1.` Ther rivet 24 includes aguide portion 25 which is internally threaded and serves a purpose to beA hereinafter described. Ar second magnetic plate 26 is dis posed within an opening 27| provided in insulating member 2 and is sov positioned relative to plate 23 that an opening therein is placed in alignment with anV opening provided through plate 23. A magnetic sleeve or core member 28 having shoulder portions 2'9 is supported thereby on plate 23, and has a shank portion 3| which. extends through the aligned openings of plates 23 and 26.. The rim of the shank portion 3|- is bent outwardly to hold plate 26 in intimate Contact with plateV 23-v and to rigidly secure. the sleeve member 28 in. position. An energizing coil 32 comprising a spool sleeve 33 of ber composition and spool washers 34, alsofof fiber composition, is disposed abou-tfthe sleeve. 28 withV the latter member being contained except for the shank portion 3|, wholly within the opening in coil 32 provided by sleeve 33. A shell or cover 36 is tted over the coil 32'.. The. cover 36 is provided with mounting flanges 31 which rest upon the magnetic plate 23. Studs... 33. passing through base and thefm-agnetic plate 23 are threaded into the nanges 3'1 to thereby secure. shell 36 to the base. A felt washer 39 is provided on top of the coil 32 and spaces the cover 3,5 from the coil. A stationary core member 4|- having a recess 42 extending'frorn the top surface thereof is carried by the covery 36, beingy secured thereto ink amar-incr similar: to that in which sleeve member 28 is secured to plate 23,. there beingshoulder portions: 43: provided on. the member 4| which bear against a magneticplate 44 and a shank portion. @which extends throughian opening in the cover, andthevrim. of. the shank portion is bent outwardly to rigidlyl X the, core member 4| in place. The core member4-| is provided with a recess lo extending from its bottom surface and being of a truncated'cone shape.-V The recess 42 extending fron-ith@V top surface of. member 4| and the recess extending from the bottom surface thereof' are. joined byV apassageway 41 for a-.purpose toibehereinafter described. Mount,- ing of the shell 36 in position. on the. base I. will place the greater portion of the core member 4I within theo-peiling in coil 32., but the length of the coremember 4| is. such` that the lower extremity thereofwillbe. spaced ay sufficient distance from core member 28 that fiux leakage therebetween is held to a minimum.

Within recess 42 a spring seat 48 and a spring 49 are disposed. A sealing plate 5| is riveted to the cover 36 and closes the recess 42' and prevents access to within the cover 36. A boss 52 is formed in the sealing plate 5| and serves as a spring seat for positioning the upper end of spring 49. A second pair of terminal studs 54 and 55 are carried by the base being held thereon by nuts 5S. To each of the studs 54 and 55, a wire 57, leading from the solenoid coil 32, is secured by a stud 58, las is also an external circuit wire (not shown) whereby electrical enrgy may be brought to the energizing coil 32. A plunger or armature 53 is disposed within the sleeve member 28 and passes through an opening in insulating member 2 and normally rests upon the surface of insulating member 3. A portion 59 of lesser diameter than the main body of the armature 53 extends from the bottom portion thereof and through an opening 6| in the insulating member 3 and is closely received thereby. A guide pin 62 formed of non-magnetic material is staked or otherwise secured to the top surface of the armature 53 and extends through passageway 41 in core member 4| into recess 42. Spring seat 48 iits over the end of pin 62 whereby upward movement of the armature 53 will be against the bias of spring 49. An extension 63 is provided at the end of portion 59 of the armature 53 and supports a movable contact assembly or switching member 64. The movable contact assembly 64 comprises a member 65 formed of insulating material and a conducting member 68 riveted thereto, with the conducting member 66 having an opening 6T through the center thereof and carrying contact surfaces 68 and 69 at opposite ends thereof adapted to bridge and cooperate with the stationary Contact faces 6 and to make and break an electrical circuit therethrough. Raised portions provided on the insulating member 65 space this member from the connector 66. EX- tension 63 of the l'armature 53 passes through an opening in member 65 and through opening 61 in connector 66. To mount the movable contact assembly 64 thereon, a springr member 13 with its spring seats 14 is provided upon the extension 63 and held thereon by a cotter pin '|5. The spring member 13 will normally exert its bias upon the insulating member 65 to hold it in its, uppermost position and against shoulder portions 1S provided on portion 59 of armature 53 as shown in Figure 2. The insulating member 65 is slotted at either end Ias at and 18, and these slotted ends are disposed about guide portions 25 and cooperate therewith to properly position the movable contact assembly 64 and to fix the path of movement thereof so that the Contact assembly will move in a substantially rectilinear path on movement of the armature or actuating member 53 unen energization and deenergization of the coil 32. A cover 'I9 formed of molded Bakelite is disposed over the movable contact assembly 64 to seal off the switch from outside access. Studs 8| threaded into guide portions 25 secure the cover to the base I.

A mounting bracket 82 is carried by the solenoid cover 3S whereby the switch may be located in the desired location.

It is to be noted that the armature 53 is guided in its movements by the guide pin 62 and the armature portion 59. The pin 62 and the armature portion 59 are closely received by the spaced concentric openings 41 and 6| provided by core member 4| and the insulating member 3 and lateral movement of the armature 53 and side pull thereon is thereby held to a minimum and there is no contact between the sides of the armature 53 and the interior surface of sleeve member 28 on movement of the armature 53 thereby avoiding friction loss.

With the construction here described, a more effective device is secured, for there is no necessity for the insertion of a brass sleeve or other liner between the interior surface of the sleeve member 28 and the armature 53 and thus the air gap will comprise only the mechanical clearance between the armature 53 and the sleeve member 28, and, therefore, the magnetomotive force required to move the armature is materially lessened over that which would be required if the air gap were to include the thickness of a brass liner.

The lateral sides 83 defining the recess 46 in the stationary core member 4| are of the same angle as the lateral sides 84 of armature 53 but the diameter of the surface 85 defining the recess is slightly greater than the diameter of the upper end 86 of the armature 53 so that there is no interference mechanically between the lateral surfaces 83 of the armature 53 and the lateral surfaces 84 defining the recess 46, and the armature 53 will complete its full stroke into engagement with surface 85 without frictional loss due to contact with the sides 83. A comparatively steep cone angle is thus utilized to provide for a relatively high initial pull on the plunger 53 without the danger of the plunger sticking tight before a full stroke has been completed.

In the operation of the device of the present invention, assuming the parts to be in the position of Figure 2, energization of coil 32 will effect an upward rectilinear movement of armature 53 against the bias of spring 49 and into sealing engagement with surface 85. Movement of the armature 53 carries extension 63 upwardly to apply force upon spring 13; this force is transmitted by the spring to the insulating member 65 to move it also upwardly to thereby carry the movable contacts 68 and 69 into bridging engagement with the stationary contacts 6 and 1 to complete a circuit therethrough. It is to be noted in Figure 4 that when the contacts are in engaged position there is a definite compression of the spring 49 which results in an application of force on the movable contacts 68 and 69 to effect a substantial contact pressure between these contacts and the stationary contacts 6 and 1.

On deenergization of the coil 32, the plunger 53 will move downwardly under the force of gravity and the bias of spring 49 to move the movable contact assembly 64 and break the circuit. The device need not be mounted in vertical position as shown, for the spring 49 is made suiciently stiff that it applies a force that will always return the plunger 53 to its deenergized position to break the circuit through the switching assembly regardless of the position in which the device is mounted.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is: n

1. An electromagnetic operator for an electric switch, comprising an insulating base, a movable armature member, an energizing coil for eiecting movement thereof and having an opening therethrough, a pair of core members disposed within said opening in said energizing coil, said core members being spaced from one another and each of said core members having openings therein, said armature member being movable for the greater part of its length within one of said core members, a non-magnetic member carried by said armature member and received by the opening in the second of said core members, and an extension on said armature member adapted to pass through an opening in said insulating base, said opening in said second core member and said opening in said insulating base being concentric whereby said armature member will be held continually spaced from the sides of the core member through which it moves for a greater part of its l-ength to effect an air gap between the armature and the sides of said latter core member comprising only the mechanical clearance therebetween.

2. An electromagnetic operator for an electric switch, comprising an armature member, an operating coil for effecting movement thereof and having an opening therethrough, a pair of magnetic members spaced from one another and disposed at either end of said opening in said operating coil, the rst of said magnetic members having an opening therethrough and receiving said armature member for movement therein on energization of said operating coil, means carried by said armature member for holding it spaced from the sides of said first magnetic member when moving therein to effect an air gap between said armature and rst magnetic member, said armature member having an end portion thereof formed in the shape of a truncated cone, said second magnetic member having a recess therein formed in the shape of a truncated cone and of a suiiiciently large diameter than the diameter of the end portion of the armature that when said end portion of said armature member is received, upon energization of said coil, engagement with the sides of the recess is avoided.

3. An electromagnetic operator for an electric switch, comprising an insulating base, a movable armature, an energizing coil for effecting movement thereof from a, rst position, said ener gizing coil having an opening therethrough, a pair of magnetic members disposed within said opening and spaced one from the other, the first of said magnetic members having an opening therethrough and receiving said armature for movement therein on energization of said energizing coil, means for centering said armature to prevent engagement with the sides of said first magnetic member, and to eiect an air gap therebetween comprised only of the mechanical clearance between said armature and the sides of said rst magnetic member, said means comprising a non-magnetic member secured at one end of said armature member and being closely receivable within an opening in the second of said magnetic members and an extension on said armature member which is closely receivable within an opening in said insulating base, said second magnetic member having a recess therein into which said non-magnetic member extends and is movable therein, spring means disposed in said recess and acting on said non-magnetic member to return said armature to said rst position upon deenergization of said coil.

4. An electromagnetic operator for an electric switch, comprising an armature member, an operating coil for eiecting movement thereof, a pair of magnetic members spaced one from the other and disposed at either end of an opening in said operating coil, the first of said magnetic members having an opening therethrough and receiving said armature member for movement therein for the greater portion of its length on energization of said operating coil, said armature member having an end portion thereof formed in the shape of a truncated cone, said second magnetic member having a recess therein formed in the shape of a truncated cone and of sufliciently larger diameter than the diameter of the end portion of the armature member that when said end portion of said armature is received, engagement with the sides of the recess is avoided, means carried by said armature member for holding it spaced from the sides of said rst magnetic member when moving therein to form an air gap between the armature and first magn-etic member, said means comprising a noninagnetic member provided at one end of said armature member and an extended portion at the opposite end of said armature member, said non-magnetic member extending into said recess in second magnetic member and through a connecting passageway and into a second recess provided therein, and spring means disposed in said second recess and acting on said non-magnetic member to return said armature to deenergize position on deenergization of the coil.

EARL F. MEKELBURG.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,745,878 Trumpler Feb. 4, 1930 2,278,967 Allen Apr. 7, 1942 2,008,275 Dyer July 16, 1935 2,174,313 y Coffey Sept. 26, 1939 2,102,761 Strobel Dec. 21, 1937 2,297,626 Lennholm Sept. 29, 1942 '768,549 Stewart Aug. 23, 1904 978,377 Humphrey Dec. 13, 1910 1,793,858 Lake Feb. 24, 1931 2,170,961 Borgkvist Aug. 29, 1939 2,238,154 Borgkvist Apr. 15, 1941 2,344,178 Sparrow Mar. 14, 1944 2,330,407 Claytor Sept. 28, 1943 FOREIGN PATENTS Number Country Date 19,486 Great Britain 1906

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