US3134869A

US3134869A - Electromagnet assembly with interfitting parts

Info

Publication number: US3134869A
Application number: US179362A
Authority: US
Inventors: Leland E Lawrence
Original assignee: Allen Bradley Co LLC
Current assignee: Allen Bradley Co LLC
Priority date: 1962-03-13
Filing date: 1962-03-13
Publication date: 1964-05-26
Anticipated expiration: 1981-05-26

Description

May 26, 1964 Filed March 13,

L. E. LAWRENCE 3,134,869 ELECTROMAGNET ASSEMBLY WITH INTERFITTING PARTS 4 Sheets-Sheet l e: 1 M 3 v 165 72 INVENTOR Z5 LELAND E. LAWRENCE '52 4-7 how/2M ATTORNEY y 26, 1964 L. E. LAWRENCE 3,134,869

ELECTROMAGNET ASSEMBLY WITH INTERFITTING PARTS Filed March 13, 1962 4 Sheets-Sheet 2 4-gl v f I 7 7 I 3 50 4-0 I 4- 4 in nu h will h i s5 19 i 3 74 M g 6' 7 A 1 55 4 2 3|- 3 65 5 =Z4 /2 32 .I

73 lNVE OR 0 5 4a] M. LELAND E. WRENCE 20 Q 66 I 4 'i BY KM,

45/35,? ATTORNEY y 26, 1964 L. E. LAWRENCE 3,134,869

4 Sheets-Sheet 3 INVENTOR z'v-fi l 72 LELAND E. LAWRENCE BY /9 lo q 53 g 38 ATTORNEY May 26. 1964 L. E. LAWRENCE 9 ELECTROMAGNET ASSEMBLY WITH INTERF'ITTING PARTS 4 Sheets-Sheet 4 Filed March 13, 1962 INVENTOR LELAND E. LAWRENCE ATTORNEY United States Patent 3,134,869 7 ELECTROMAGNET ASSEMBLY WITH INTERFITTING PARTS Leland E. Lawrence, Wauwatosa, Wis., assignor to Allen- Bradley Company, Milwaukee, Wis, a corporation of Wisconsin Filed Mar. 13, 1962, Ser. No. 179,362 17 Claims. (Cl. 200-87) This invention relates to electromagnets for switches and the like, and it more particularly resides in an improved electromagnet assembly with interfitted parts that contribute to improved use and operation.

The electromagnet assembly of this invention includes a frame, a coil and magnetic yoke received in the'frame, a movable contact carrying actuator that is slidably mounted by the frame and carries a magnetic armature, and a protective cover. It is the general object of this invention to provide an electromagnet assembly of this type that includes a number of novel structural features which serve to improve the operation of the assembly, reduce wear on the various elements, allow for economical and efficient manufacture, simplify assembly, and prevent assembling the various parts in improper orientations.

It is one of the specific objects of this invention to proyide a frame and actuator that have mating tapered surfaces to' prevent placing the actuator in the frame in any but its proper orientation.

It is another object of this invention to provide a coil that has openings to receive the yoke, the yoke and the coil openings being provided with mating fillet and cutout portions to prevent improper assembly.

It is another object of this invention to provide a coil that fits through an opening in the protective cover and is held therein by a resilient holding means which holds the coil securely in place during operation of the electromagnet assembly to prevent the Wear and lead breakage which might otherwise result from the hammering action of the armature and which also allows for the cover, coil and yoke to be sub-assembled and inserted into the frame as a unit during final assembly.

It is another object of the invention to provide abutments on the coil that aid in sub-assembling the coil, cover and yoke and that cooperate with mating ledges in the frame to locate and hold the coil in proper orientation and prevent improper assembly.

It is another object of the invention to provide mating beveled surfaces on the yoke and frame to prevent the yoke from being improperly inserted in the frame.

It is another object of the invention to provide a tapered key mounting for the yoke in the frame to prevent improper assembly and to prevent rocking or whipping of the yoke during operation of the electromagnet.

It is another object of this invention to provide an auxiliarycontact assembly for incorporation in a control circuit in which an auxiliary contact housing is formed as an integral part of the protective cover of the electromagnet assembly and the lever foroperating the auxiliary contacts, which is itself operatediby a crossbar carried by the actuator, is pivotally mounted in the housing with a maximum bearing supportand is soformed as to prevent damage to the lever 'or auxiliary contacts resulting from improper alignment of the lever and crossbar during assembly.

Itis another object of this invention to provide a shim formed .of a material having natural lubricity between the 3,134,869 Patented May 26, 1964 facing surfaces of the cover and actuator to prevent excessive wear of these and associated elements due to repeated operations of the actuator, which wear could otherwise cause deleterious accumulations of dust or misalignment of the parts of the electromagnet.

It is another object of this invention to provide an armature that is securely but resiliently mounted on the actuator and cooperates with ribs formed in the frame and protective cover to prevent the armature from being driven out of alignment with the actuator by dropping or other abuse of the assembly.

It is another object of this invention to provide an actuator that has visible markings thereon which may be viewed through cutout portions of the protective cover to indicate visually the position of the actuator.

It is another object of this invention to arrange the various tapered and beveled surfaces of the elements in such a manner as to provide sufficient draft for die casting of the frame.

It is another ,object of this invention to provide an electromagnet assembly incorporating the foregoing features which can be efficiently and economically manufactured.

Other objects and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawings, forming a part hereof, in which by way of illustration and not of limitation a specific embodiment of the invention is shown.

In the drawings:

FIG. 1 is a front view in elevation of an electromagnetic switch including an electromagnet assembly formed according to this invention,

FIG. 2 is a side view in elevation, with parts broken away and in section and other parts shown in dotted lines, of the switch of FIG. 1,

FIG. 3 is a fragmentary View in cross-section taken along the plane 3 3 shown in FIG. 1,

' FIG. 4 is a fragmentary view in cross-section taken along the plane 4-4 shown in FIG. 1,

FIG. 5 is a fragmentary view in along the plane 55 shown in FIG. 4, FIG. 6 is a fragmentary view in cross-section taken along the plane 66 shown in FIG. 3,

FIG. 7 is a view in perspective of a sub-assembly of the switch of FIG. 1- including the coil, yoke and protective cover,

FIG. 8 is a view in perspective of the actuator of the switch of FIG. 1, and

FIG. 9 is a view in perspective of the electromagnet frame and mounting plate of the switch of FIG. 1.

The electromagnetic switch shown in the drawings includes a sheet metal mounting plate 1 provided with a cross-section taken .set of three apertures 2 for mounting upon apanel, or in an enclosure, as desired. The configuration of the plate 1 is most clearly shown in FIG. 9, and as viewed therein, one of the apertures 2 is an inverted keyhole slot at the top and the others constitute a pair of round holes at the bottom. A metal frame, indicated generally by the numeral 3, is mounted on the plate 1 by means of rivets 4, which are shown in FIGS. 2, 3 and 9. The frame 3 is preferably formed of die-cast aluminum, and as previously stated it is among the special advantages of this in vention that the frame 3 can be die cast so as to be given the configuration to be described. Also, the frame 3 has heat transmitting properties as are discussed in US. Letansasea ters Patent No. 2,903,537 which discloses a frame having some similarities to the frame of the present invention.

As seen most clearly in FIG. 9, the frame 3 is of rather complex configuration, and includes a centrally located rectangular coil socket 5 that is provided in its upper wall with a channel shaped cutout portion, or recess 6. The recess 6 is also shown, in section, in FIG. 3, and it imparts an irregular configuration to the coil socket, when viewed from the front, to act as a guideway for orientation of parts during assembly, as will hereinafter be discussed. Immediately above the coil socket 5, the frame 3 extends outwardly to provide a vertical yoke receiving riser 7 that defines a yoke socket with an upwardly and forwardly inclined beveled upper edge 8. Such beveled edge forms another guide for correct orientation of parts during assembly, and gives an irregular configuration to the yoke socket. A pair of laterally spaced,

' forwardly extending yoke receiving arms 9 which determine the lateral limits of the yoke receiving riser 7, and hence partly define the yoke socket, are also disposed immediately above the coil socket 5. The arms 9 are each provided with inwardly and forwardly opening keyway slots 10 which, as can be seen in FIG. 4, are tapered so as to have a greater vertical dimension at their forward ends, whereby the taper presents divergent surfaces A horizontal mortise slot 23 extends through the midsection of the yoke 21, and a phenolic impregnated, laminated canvas key piece 24 of a generally rectangular surface configuration extends through the slot 23 to overhang on either side of the yoke 21. The overhanging ends of the key piece 24 are received in the keyways 10 of the arms 9, and as specifically shown in FIGS. 3 and 4 the key piece 24 and slot 23 are both tapered, or divergent, to match the taper, or divergency, of the keyways 10. Thus, the key piece 24 can be inserted in the yoke slot 23 only when its narrower edge is in alignment with the narrower end of the slot 23, which is at the rear end of the yoke 21. Also, the key piece 24 cannot be inserted in the keyways 10 unless its narrower edge is facing towards the rear of the device. Thus, the yoke 21 and key piece 24 can be sub-assembled in only one orientation; and this subassembly can be inserted into the frame 3 in only one way to prevent end-for-end reversal during assembly.

The divergent taper of the keyways 10 also aids in I die casting the frame 3 by providing sufficient draft.

for each slot 10. As seen most clearly in FIG. 6, the

outer, or side, surfaces 11 of the arms 9 are also divergent and taper inwardly from the rear to the front of the arms 9. The arms 9 are also provided on their lower surfaces with coil locating ledges 12 and at their forward ends with threaded screw receiving openings 13.

The frame 3 also includes at its lower corners a pair of forwardly extending actuator receiving posts 14 that are generally trapezoidal in cross section configuration. The posts 14 include inwardly and upwardly facing oblique surfaces 15 and inwardly facing vertical surfaces 16, and as seen in FIG. 5, the surfaces 16 are tapered outwardly from the rear of the posts 14 to diverge from one another. The posts 14 are preferably cut away on their outer side surfaces and on their bottom surfaces as at 17 to provide electrical clearance for protective relays (not shown) on either side of the frame and to provide cover locating surfaces for mating engagement with a cover as will be hereinafter described. Similarly as the arms 9, the posts 14 also include in their forward ends threaded screw receiving openings 18.

The frame 3 is further characterized by the inclusion of a set of four forwardly facing, vertically disposed actuator guide surfaces 19 that are located alongside the arms 9 and the posts 14. The two surfaces 19 associated with the posts 14 lie to their immediate inside, so as to have common boundaries with the surfaces 15 and 16, and extend upwardly for a short distance above the posts 14. The remaining two surfaces 19 are immediately adjacent the outer sides of the arms 9 to form the base of the arms at these points, and all of the surfaces 19 lie in a common vertical plane. An armature restricting rib 20 is also shown in FIGS. 3, 4 and 9 as a part of the frame 3, and it extends horizontally between the posts 14. To complete the frame 3 a horizontal mounting ledge extends across the top to receive a contact hood to be described.

Referring now to FIGS. 3 and 6, a generally U-shaped, laminated, magnetic yoke 21 is mounted between the arms 9 in an inverted position, so that its two legs 27 project downwardly. The rear surface of the yoke 21 is adjacent the yoke receiving riser 7, and the upper rear edge 22 of the yoke 21 is beveled to mate with the beveled edge 8 of the riser 7. The beveled edges 22 and 8 must mate in order for the yoke 21 to be inserted fully into the frame 3, and it is therefore impossible to mistakenly reverse the yoke 21 end-for-end during assembly of the switch, because of the irregular configuration of the yoke socket. Thus, when the magnet is assembled the magnetic yoke 21 is received in the yoke socket with definite orientation.

Further, the matching taper of the key piece '24 provides a more adequate bearing area between the upper surface of the key piece 24 and upper side of the keyways 10 than would be present if an untapered key piece were used in a tapered slot, thus helping to prevent rocking or whipping of the key piece 24, and the yoke 21, when the yoke 21 is struck during operation of the switch.

Referring now to FIGS. 3, 4, 6 and 7, there is shown a generally rectangular coil indicated generally by the reference numeral 25. The lengthwise dimension of the coil 25 extends in the fore and aft direction, so that one end will be received within the coil socket 5 of the frame 3. This end of the coil 25 is that which is viewed in FIG. 7, and it is seen that the coil end will conform quite closely with the socket 5, so that a fairly snug fit will be had which adequately supports the after end of the coil 25 in a fixed position. As is most clearly shown in FIG. 3, the coil 25 has a pair of windings and supporting and insulating plates, all encased in an insulating shell formed of an epoxy or other suitable resin, and

the central eye of each winding is open to define a pair of spaced coil openings 26 which receive the magnetic members of the switch.

The downwardly extending legs 27 of the yoke 21 extend downwardly into the coil openings 26 from the upper side of the coil 25, and as can be seen most clearly in FIG. 6, fillets 28 are provided along the left rear corner of the rear coil opening 26 and along the left front corner of the front coil opening 26, which mate with cutout edges 29 formed in each yoke leg 27 by provision of a side plate 30 for the yoke 21 that is somewhat shorter than its laminations. The cutout edges 29 and fillets 28 must mate before the yoke legs 27 can be inserted into the coil openings 26 and, therefore, it is impossible to sub-assemble the yoke 21 and coil 25 in any but their one proper orientation.

As best seen in FIG. 7, the coil 25 is also provided with an integrally formed boss 31 at the rear of its upper surface, and with a pair of integrally formed side bosses 32 also on its upper surface, but alongside the magnetic yoke 27 when it is assembled with the coil. When the coil 25 is inserted into the frame 3, the boss 31 is received in the recess 6 of the coil socket 5, to thereby match the irregularity of the coil socket configuration and to have the guideway presented by the recess 6 orientate the parts in assembly. Also, the rear edges of the bosses 32 abut against the ledges 12 formed in the arms 9. These engagements serve to locate and fix the coil 25 in proper position in the frame 3, so that the coil 25 cannot be reversed, i.e. turned over, during assembly. In addition, the coil 25 cannot be reversed, end-for-end, since it has terminals 72 which must appear at the front.

As seen most clearly in FIGS. 3 and 6, the coil 25 is also provided at the front of its upper surface with a resilient holding member '33 in the form of a flat spring extending across thewidth of the coil "25 and provided with a cutout portion in register with the front coil opening 26.

The holding member 33 is formed .ofany suitable resilient -erally by the numeral 36, seen most clearly as the principal element in the perspective views of FIG. 8, is slidably mounted, when the switch is fully assembled, in the frame 3 and includes a base portion 37, a pair of side members 38 and a crossbar portion 39. The actuator 36 is preferably'formed of a sturdy insulating material such as a phenol formaldehyde molding compound which will provide bearing surfaces for the actuator as it moves upward and downward in a guided movement.

When the actuator 36'is assembled with the frame 3 the base portion 37 extends crosswise between the actuator receiving posts 14, as shown in FIG. 5, and the lower ends of the side members 38, Where-they merge with the base portion 37, cross over the tops of the posts 14' and extend upwardly alongside the coil 25 and the outer faces of the arms 9. The crossbar portionj39 joins the upper ends of the side members '38 and extends across the upper face of the magnetic yoke 21.

During operation of the switch, the back faces ,of the side members 38 slide along the slide surfaces 19 of the frame 3 in a vertical reciprocating motion, and at the lower ends of the side members 38 the actuator36 is provided with oblique surfaces 40 which engage with and mate the surfaces 15of the posts14 to limit downward movement of the actuator 36. The vertical outer side surfaces 41 which define the crosswise ends of the base .portion37, and which are immediately below the oblique surfaces 40, are tapered. outwardly from the rear to the front to match the taper of the surfaces 16 of the posts 14. Further, the inner. surfaces ofthe side members 38 .areprovided attheir upper ends with inwardly tapered guide surfaces 42 which. mate withthe tapered surfaces 11 of the arms -9. Since the

surfaces 42and

11 and 41 and 16 must mate before theactuator 36 can be inserted fully into the frame 3, it is impossible to reverse the actuator 36 face for-faceduringassembly. The tapered surfaces 16 and 11 are of further benefit in providing sufli- ..cient draft for die casting the frame 3, .and the surfaces 41 and'42 are of benefit in providingdraft for molding the actuator 36.

Theforward surface of each side member 38 is provided with an indicating section 43. painted, or otherwise colored, soas to contrast distinctly with the remainder of .the members 38. The contrasting indicating sections 43 enable the position of the actuator 36 to be determined visually in a manner .tobe hereinafter described.

An upwardly opening, generally. U-shaped. laminated magnetic armature'44 is mounted on thebase37 of the :actuator 36 by means of a pair of side plates 73 having :sidewardly extending flanges 45 which are received in .aslot 46 inthe base '37. ,A flat insulating shim 47 formed .of aflphenolic molding compound is placed below the flanges 45 and a resilient flat holding spring48 of any suitable material is interposed between the shim .47 and base .37. Although the spring-48 is resilient, it is'preferably quite strong to minimize any movement of the armature -44 with respect to the actuator36, while still providing suflicient resilience: to take upsome of the shock transmittedduring closing'oropening of the switch.

The switch also includes aicaprlike front cover indicated generally by the numeral 49and preferably molded of an insulating material such as a phenol formaldehyde mold- ..ing compoundysimilar to that usedforsthe actuator .36.

The cover 49 at its lower corners is provided with inan actuating position.

'wardlyiextending rims 50 which mate with the cover 10- cating surfaces .17 of the actuator receiving posts 14 to locate and. hold the cover 49 in position. Generally triangularcutout portions 51 are provided on each side of the cover49-and are so located with respect to the indicating sections 43 of the actuator 36 that the. indicating sections. 43 can be viewed through the cutout portions 51 only when the actuator 36 has been moved upwardly to Thus by looking through thecutout portions 51 from the front of theswitch it is possible to determine whether the actuator 36 has or has not moved to its actuating position.

The cover 49 is also provided with a generally rectangular aperture 52 extending across its front facethrough which protrudes the forward end of the coil 25. presenting the terminals 72. The spring 33 is interposed between the upper front surface of the coil 25and the upper side of the aperture-52, .to hold the coil 25 securely in place with respect to the cover 49. This serves to hold the coil '25 firmly, but resiliently in place during operation of the switch to prevent lead breakage and wear which might otherwise occur because of thehammering action of the magnetic elements. Also, since the coil 25-and cover 49 are held tightly together by means of the spring 33, it is possible to insert the yoke 21 into the coil 25 and the coil 25 intothe cover 49 to create the sub-assembly shown in between the rear face of the cover 49 and the front surfaces of the side members 38 of the actuator 36 to prevent the wear and resultant accumulation of dust which might otherwise occur because of the sliding action of these elements on one another during the operation of the switch. The provision of the shims 53 also serves to preventwear on other elements of the switch, which might resultshould the actuator 36 become misaligned after being worndown.

Four assembly screws 54 pass through the cover 49 and are received in the threaded

openings

13 and 18 of the arms 9 and posts 14, respectively, to hold the ,cover 49 in place on the frame 3. The screws 54 are preferably plus threaded with the threaded portion being vof such length as to be to the rear of relatively tight fitting openings in the shims 53, whereby the threads on the screws 54 act as a retainer for the shims 53 to hold the shims 53 in place during assembly. Thus the shims 53 and mounting screws 54 form a part of the sub-assembly of FIG. 7. Also, the openings in the cover .49 which receive the screws 54 are preferably provided with severalthreads at their rear ends to act as a retainer for the screws 54 during assembly and to compens ate for the reduced diameter of the screw shaft, due

to the plus threading, thus locating the screws 54 with respect to the cover 49.

The cover 49 is also provided at its top center with an integrally formed, box-like auxiliary contact enclosure '55. A pin .56 passes transversely through the enclosure 55 and is preferably formed of an acetal polymer, and is held in place in any desired manner. The pin 56 pivotally mounts a short quill 57 that functions as an integral bearing portion of an auxiliary contact lever 58. .The auxiliary contact lever 58 is preferably formed of nylon, since nylon can easily be injection molded to form the tube like quill portion 57, which serves to pro- FIG. 3, is seated ,at oneend against the interior'wall of the enclosure 55, and works at itsopposite end against the lever 58 to urge the lever 58 in a counterclockwise direction, as viewed in FIG. 3. At its forward end, the lever 58 is provided with an opening 61 through which passes a transversely disposed, normally open bridging contact 62 that is preferably formed of a resilient, electrically conductive metal with suitable contact surfaces at both ends. A spring 63 seated against the upper wall of the opening 61 serves to urge the bridging contact 62 against the lower wall of the opening 61. A pair of stationary contacts 64 are also mounted within the enclosure 55, on opposite sides of the lever 58, and extend outwardly to present terminals 65 for connection into an auxiliary circuit. This auxiliary contact structure operates in the usual manner, in that when the actuator 36 is raised the lever 58 is caused to pivot in a clockwise direction, as seen in FIG. 3, thus moving the bridging contact 62 against the bias force of the spring 60, into closed position with respect to the stationary contacts 64. The enclosure 55 may also mount a second set of stationary contacts, not shown, above the bridging contact 62 in a position that they are engaged by the contact 62 when in its raised position of FIG. 3. In this fashion normally closed contacts may be provided as well as normally open contacts, and they can be advantageously used in reversing switch applications and the like.

The lever 58 is arranged to have a slight overtravel, and this in efiect causes the bridging contact 62 to be lifted, against the spring 63, off the bottom wall of the opening 61 after initial contact, the spring 63 thereafter serving to hold the bridging contact 62 in closed position. The lever 58 extends downwardly below the opening 61 to provide a stop 75 engageable with the bottom Wall of the enclosure 55 to limit the pivotal movement of the lever 58. This prevents any damage which might be caused to the lever 58 or the bridging contact 62 should the lever 58 be pivoted too far during assembly of the switch, as when it is attempted during assembly to lift the lever 58 onto the upper surface of the crossbar 39 while the actuator 36 is in its upper position. Also, the rear end 74 of the lever 58 is quite blunt to prevent it from sliding under the crossbar 39 if the actuator 36 is in a slightly raised position during assembly.

As seen in FIGS. 3 and 4, the cover 49 is also provided with a horizontally extending, integrally formed rib 66 which is alongside the forward end of the armature 44 with a slight clearance therebetween. The rib 66 and the rib 20 in the frame 3 serve to prevent dislocation of the armature 44 should the switch be dropped or otherwise abused.

The crossbar 39 of the actuator 36 forms a support for movable contact carrying cages 67 which carry movable contacts 68 and extend upwardly into an arc enclosure indicated generally at 69. Stationary contacts 70, seen in FIG. 2, are mounted in the enclosure 69 and terminals 71 are provided for connection into a line circuit. No attempt is made herein to describe the contact assembly of the switch with any particular degree of specificity, since it will be well understood that any number of contact assemblies could be used and that the invention herein resides essentially in the electro magnetic elements hereinbefore described. The operation of the switch of this invention will also be understood without being described in any great detail, it being suflicient to note that when the coil 25 is energized the armature 44 is attracted toward the yoke 21 whereby the actuator 36 is moved upwardly to bring the movable contacts 68 into closed position with the stationary contacts 69. Upon deenergization of the coil 25 the actuator 36 falls downwardly of its own weight to break the circuit.

The electromagnet of this invention has demonstrated excellent mechanical life characteristics, with operations of small size switches, for example, running upward to 40 million and above. The interfitting parts, in which the actuator is guided by bearing surfaces of substantial area that exhibit little wear, and in which the coil is held securely for minimal vibration, have contributed to the life obtained. Further, the mounting of the magnetic yoke with a key piece extending entirely through its central portion and resting with a small clearance in the adjacent arms has contributed to the results obtained. When the armature strikes the magnetic yoke shock is absorbed in the frame and the phenolic key piece and in the slight motion of the yoke provided by the small clearance between it and the key piece and between the key piece and frame. The use of subassembly of FIG. 7 can be of advantage in assembly of the switch. The sub-assembly of FIG. 7 is self-sustaining by reason of the retaining spring 33, and in assembling the device in this manner the actuator assembly of FIG. 8 is first placed in the frame 3, from the front, and then with the actuator in its lower position, the sub-assembly of FIG. 7 is brought into the frame 3, again from the front, and the mounting bolts 54 are secured. In order for the sub-assembly to be inserted, the actuator 36 must be in its lower or down position, thus preventing damage to the lever 58 by engagement with the edge or lower surface of the crossbar 39. The parts thus interengage Without any complication, and the possibility of mismatching any of the elements is precluded. To complete assembly of the switch the front hood portion 69 is mounted in place. If desired, however, the switch can also be readily assembled without first creating the subassembly of FIG. 7 since, as hereinbefore discussed, the various parts and the relationships between them prevent improper assembly even when the parts are inserted individually.

I claim:

1. In an electromagnet the combination comprising: a base frame having a pair of forwardly projecting arms extending therefrom that are laterally spaced with respect to one another to present facing inner surfaces, said arms being provided with keyway slots that open along said facing inner surfaces and at the outer ends of the arms and which have divergent surfaces; said frame also including a yoke socket that is between said arms and is of an irregular configuration; a magnetic yoke having an after end received in and matching the.

configuration of said yoke socket and a keypiece slot extending therethrough, said keypiece slot having divergent surfaces matching those of said keyway slots and aligned with said keyway slots when said yoke is received in said yoke socket; a keypiece extending through the keypiece slot and outwardly on either side of the yoke to be received in said keyway slots, said keypiece having divergent surfaces matching said keyway and keypiece slots; an operating coil mounted on said frame; and a. magnetic armature in facing relation to said yoke for operation therewith in response to said coil.

2. In an electromagnet the combination comprising: a frame having a coil socket with a forwardly and rearwardly extending guideway that provides an irregular configuration for the socket, and a pair of spaced arms extending forwardly from points adjacent the coil socket that are provided on their lower surfaces adjacent the coil socket with forwardly facing coil locating ledges; and a coil having an after end with a projection mating said guideway which is received in and matches the configuration of the coil socket and which coil has further projections extending therefrom that are engageable with the coil locating ledges, whereby the coil may only be inserted with desired orientation with respect to said frame.

3. In an electromagnet the combination comprising: a frame having a coil socket with a guideway that imparts an irregular configuration for the socket; a pair of laterally spaced arms extending forwardly from above the coil socket which have facing keyway slots, and a yoke socket located between said arms and above said coil socket which has a guide that imparts an irregular configuration to the yoke socket; a coil having an after end received in and matching the configuration of the coil socket guidway whereby it may only be inserted in the coilsocket with the proper side facing upwardly, said coil having a pair of openings with one to the front of the other and wherein at least one has a yoke receiving guideway; a U-shaped yoke with ends thereof insertable in said coil openings with one yoke end matching said yoke receiving guideway for receipt of said yoke in the coil openings only upon mating the guideway and matching yoke end, and the after'end of the yoke being of an irregular configuration that matches said guide of said yoke socket in said frame for receipt of said yoke in the yoke socket only upon matching said irregular yoke end with said guide, said yoke also having a keypiece slot extending therethrough which aligns with said keyway slots; and a keypiece extending through said keypiece slot and outwardly on either side of the yoke to be received in said keyway slots.

4. In an electromagnet the combination comprising: a frame having a coil socket with a recessformed in one side thereof, a pair of spaced arms extending forwardly from above the coil socket, said arms having facing keyway slots that open along the facing inner surfaces and at the forward ends of the arms with the upper and lower surfaces of the slots being divergent from rear to front and coil locating ledges formed on their lower surfaces, and a 'yoke socket between the arms with an oblique orientating surface along one edge thereof; a coil having an after end that fits within the coil socket and has a raised boss thereon that is received in the recess of the coil socket, a pair of openings extending vertically therethrough that are provided with a fillet along at least a portion of one edge, and a pair of raised bosses alongside the openings that are engageable with the coil locating ledges; a magnetic yoke the after end of which is received inthe yoke socket and is provided with an oblique surface matching the orientating surface thereof, said, yoke having a pair of downwardly extending legs received in the coil openings and provided with cutout portions matching the fillets in the openings and a keypiece slot extending transversely therethrough the upper and lower surfaces of which are divergent from rear to front; and a keypiece extending through the keypiece slot of theyoke, and outwardly on either side thereof to be received in the keyway slots of the arms, the upper and lower surfaces of the. keypiece being divergent from rear to front to match the divergent surfaces of the keyway and keypiece slots. t

5. In an electromagnet the combination comprising: a coil havinga pair of spaced irregular openings therethrough; a yoke having a pair of extendinglegs received in and. matching the irregular coil openings; a cover having an opening through which an end of the coil is received; and a resilient holding member interposed between the coil and cover to resiliently hold the same against relative movement.

6. In .an electromagnet the combination comprising; a magnetic yoke havinga pair of extending legs atleast one of which. is provided, with a cutout edge; a coil having spacedopenings to receive the legs of the yoke, at least 'one of said openings being provided with a fillet corresponding to the. cutout edge of a leg, said fillet being positioned to receive said yoke only upon orientation of said yoke with the cutout edge of the yoke in position match ing thefillet, to assemble. the yoke, with the coil in proper orientation, said coil also having a pair of raised bosses lying alongside theopenings; a cover having anopening for receiving an end of the coil therethrough, said bosses being engageable'with the cover toilimit movement ofthe coil" through the opening; and a resilient holding member carried by the coil; and interposed between the coil and cover to resiliently hold the coil and cover against relative movement. V V

7. In an electromagnet the combination comprising:

a frame having a coil socket of an irregular configuration, a pair of spaced arms extending forwardly from above the coil socket having facing keyway slots with divergent surfaces, the outer surfaces of the arms being divergent, a yoke socket between the arms that has an irregular, configuration, and a pair of spaced posts extending forwardly from below the coil socket having divergent surfaces; a coil having an after end that fits Within and matches the configuration of the coil socket and having an irregular opening extending vertically therethrough; a magnetic yoke the after end of which is received in and matches the configuration of the yoke socket and having a downwardly extending leg received in and matching the coil opening and having a divergent keypiece slot extending transversely therethrough; a keypiece extending through the keypiece slot of the yoke and outwardly on either side thereof to be received in the keyway slots of the arms, the surfaces of. the keypiece being divergent to match the divergent surfaces of the keyway and keypiece slots; and a vertically reciprocable armature carrying actuator having divergent surfaces matching and guidingly engageable with the divergent surfaces of the arms and posts.

8. In an electromagnet the combination comprising: a frame having a coil socket of an irregular configuration, a pair of spaced arms extending forwardly from above the coil socket having facing keyway slots with divergent surfaces, the outer surfaces of the arms being divergent, and the lower surfaces of the arms being provided with coil locating ledges, a yoke socket of an irregular configuration between the arms, and a pair of spaced posts extending forwardly from below the coil socket having facing inner surfaces that are divergent and inwardly and upwardly facing actuator blocking surfaces and having cover locating surfaces; a coil having an after end that fits within and matches the coil socket and having an irregular opening extending vertically therethrough and having a pair of projections on its upper surface that are engageable with the coil locating ledges; a magnetic yoke the after end of which is received in and matches the yoke socket and having a downwardly extending leg received in and matching the coil opening and having a keypiece slot extending transversely therethrough that has divergent surfaces; a keypiece extending through the keypiece slot of the yoke and outwardly on either side thereof to be received in the keyway slots of the arms, the surfaces of the key piece being divergent to match the divergent surfaces of the keyway and keypiece slots; a vertically reciprocable actuator having side members slidably supported by the frame, the facing inner surfaces of the side members being divergent to match and guidably engage the outer surfaces of the arms, a crossbar portion extending horizontally between the upper ends of the side members above the arms and a base extending horizontally between the lower ends of the side members, the outer surfaces of the base being divergent to match the divergent surfaces of the posts, the actuator being provided at the outer surfaces of the junctures of the side members and base with surfaces matching the blocking surfaces of the posts to limit downward movement of the actuator; an armature mounted on the base of the actuator; a cover releasably secured to the forward ends of the posts and arms extending rearwardly to rest against the cover 10- cating surfaces of the posts and serving to guide the actuator in its vertical movement, said cover having an opening therethrough which receives the forward end of the coil; and a resilient holding member interposed be tween the coil and cover to resiliently hold the same against relative movement.

9. The combination of claim 8 wherein the forward surfaces of the side members are provided with visible markings and the cover is provided with cutout portions through which the markings can be viewed.

10. The combination of claim 8 wherein thetcover includes an auxiliary. contact housing and there is provided an auxiliary contact lever that is pivotally mounted intermediate its ends in the housing and has a blunt after end that rests upon the crossbar portion of the actuator and stops formed at its forward end to limit its pivotal motion in the housing.

11. The combination of claim 8 in which the frame and cover are provided with ribs to limit forward and backward movement of the armature.

12. In an electromagnet the combination comprising: a frame having a coil socket with a recess formed in one side thereof, a pair of spaced arms extending forwardly from above the coil socket having facing keyway slots that open along the facing inner surfaces and at the forward ends of the arms, the upper and lower surfaces of the keyway slots being divergent from rear to front, the outer surfaces of the arms being convergent from rear to front and the lower surfaces of'the arms being provided with coil locating ledges, a yoke socket shelf between the arms with an oblique orientating surface along one edge thereof, a pair of spaced posts extending forwardly from below the coil socket having facing inner surfaces that are divergent from rear to front and inwardly and upwardly facing oblique actuator limiting surfaces and having cover locating surfaces on their lower and outer surfaces, and actuator guide surfaces extending vertically from outside the arms to inside the posts; a coil having an after end that fits within the coil socket and has a raised boss thereon that is received in the recess of the coil socket and having an opening extending vertically therethrough that is provided with a fillet along at least a portion of one edge and having a pair of spaced raised bosses on its upper surface the rear surfaces of which rest against the coil locating ledges; a magnetic yoke the after end of which is received against the yoke receiving shelf and is provided with an oblique surface matching the orientating surface thereof and having a downwardly extending leg received in the coil opening with a cutout portion matching the fillet in the opening and having a keypiece slot extending transversely therethrough the upper and lower surfaces of which are divergent from rear to front; a keypiece extending through the keypiece slot of theyoke and outwardly on either side thereof to be received in the keyway slots of the arms the upper and lower surfaces of the keypiece being divergent from rear to front to match the divergent surfaces of the keyway and keypiece slots; a vertically reciprocally movable actuator having side members guidably engageable by the guide surfaces of the frame, the facing inner surfaces of the side members being divergent to match the outer surfaces of the arms, a cross bar portion extending horizontally between the upper ends of the side members above the arms, and a base extending horizontally between the lower ends of the side members, the outer surface of the base being divergent to match the divergent surfaces of the posts, the actuator being provided at the outer surfaces of the junctures of the side members and base with oblique surfaces matching the oblique surfaces of the posts; an armature mounted on the base of the actuator and having an upwardly extending leg received in the coil opening; a cover releasably secured to the forward ends of the posts and arms and extending rearwardly to rest against the cover locating surfaces of the posts and serving to guide the actuator in its vertical movement, said cover having an opening therethrough which receives the forward end of the coil; and a resilient holding member carried by the coil and interposed between the coil and cover to resiliently hold the same against relative movement.

13. In an electromagnet having a base frame, a coil and magnetic yoke in mounted relation to said frame, and a magnetic armature cooperatively related with said coil and magnetic yoke, the combination comprising: an actuator reciprocably movable alongside said frame by said armature which includes a cross bar portion; a cover to the front of said base frame that is fastenable there to and which includes a contact hood at the top front thereof; contacts within said contact hood; and a contact actuator mounted by the cover extending from within said contact hood to the rear thereof to overhang said actuator crossbar in the path of travel of the crossbar, the portion of said contact actuator in the path of travel of said crossbar being thickened to strike said crossbar when the crossbar is in a raised position during mounting of the cover, to thereby preclude insertion of the contact actuator beneath the crossbar.

14. In an electromagnet an assembly of parts comprising a coil with a molded body having a pair of openings as viewed from the top, with one opening toward the coil front and the other toward the coil rear; a magnetic yoke of inverted U-shape in which each depending end of the yoke fits within a coil opening and the yoke sits astride the coil and is carried thereby; a cover that receives the forward end of said coil and the forward end of said yoke; and a keypiece extending transversely through said yoke with ends that emerge from and overhang beyond the sides of said yoke; said coil, cover, yoke and keypiece constituting a sub-assembly of the electromagnet; the assembly of the electromagnet further comprising: a base having a coil socket that receives the after end of said coil, a pair of forwardly projecting arms that are above said coil socket and laterally spaced with a yoke socket therebetween, and that have slots to receive said keypiece for mounting the yoke in said yoke socket; a pair of laterally spaced posts beneath said coil socket which also project forwardly; a movable actuator having an armature mounting portion beneath said coil and between said posts and side arms that pass alongside said forwardly extending arms, and a U-shaped magnetic armature mounted by said actuator with ends aligned with said coil openings for entry from beneath; said actuator and armature being mountable together on said base, and said pre-assembly of coil, yoke, cover and keypiece then being slidable into the assembly with said cover mating against the forward ends of said arms and posts.

15. The electromagnet of claim 14 in which said actuator has a cross piece that connects between said side arms and extends above said magnetic yoke; and further having a contact assembly carried by said cover which includes an operating arm extending into the path of travel of said actuator cross piece.

16. The electromagnet of claim 14 in which said cover has side portions that are to the front of said actuator side arms, such side portions having cut outs to make said side arms visible from the front, and said side arms having marking indicia for movement into and out of alignment with said cut outs.

17. In an electromagnet the assembly of a coil having a molded body that presents a hard, non-deformable exterior with a pair of openings as viewed from the top, one opening being toward the coil front and the other toward the coil rear, and said coil having terminals at its forward end; a magnetic yoke of inverted U-shape with each depending end of the yoke fitting within a coil opening and the yoke sitting astride the coil a cover fitting snugly over the forward end of said coil and having an opening through which said coil terminals protrude, said cover also receiving the forward end of said yoke and extending laterally from the sides and the bottom of said coil; and a keypiece extending transversely through said yoke with ends that emerge from and overhang beyond the sides of said yoke; said coil, cover, yoke and keypiece comprising a subassembly with firm fits between parts; the assembly of the electromagnet further comprising: a base having a coil socket that receives the after end of said coil, a pair of forwardly projecting arms that are above said coil socket and laterally spaced to receive said yoke therebetween and having slots to receive said keypiece for mounting and sustaining the weight of the yoke, and a pair of posts beneath said coil socket which also project forwardly and are laterally spaced;

a movable actuator having an armature mounting portion beneath said coil and between said posts and extending upwardly over the posts and merging with side arms that pass alongside said forwardly extending arms for guided vertical movement; and a U-shaped magnetic armature mounted by said actuator with ends aligned with said coil openings for entry from beneath; said actuator and armature being mountable together on said base and said pre-assembly of coil, yoke, cover and keypiece then being slidable into the assembly with said margins of said cover mating against the forward ends of said arms and posts and closing over the front of said actuator and armature.

References Cited in the file of this patent UNITED STATES PATENTS Besag et al. Aug, 28, White Oct. 7, Lawrence Sept. 8, Burch Feb. 9, Jelley July 25, Furnas et a1. May 15, Kruzic Oct. 23,

FOREIGN PATENTS Germany June 11,

Claims

1. IN AN ELONGATED THE COMBINATION COMPRISING: A BASE FRAME HAVING A PAIR OF FORWARDLY PROJECTING ARMS EXTENDING THEREFROM THAT ARE LATERALLY SPACED WITH RESPECT TO ONE ANOTHER TO PRESENT FACING INNER SURFACES, SAID ARMS BEING PROVIDED WITH KEYWAY SLOTS THAT OPEN ALONG SAID FACING INNER SURFACES AND AT THE OUTER ENDS OF THE ARMS AND WHICH HAVE DIVERGENT SURFACES; SAID FRAME ALSO INCLUDING A YOKE SOCKET THAT IS BETWEEN SAID ARMS AND IS OF AN IRREGULAR CONFIGURATION; A MAGNETIC YOKE HAVING AN AFTER END RECEIVED IN AND MATCHING THE CONFIGURATION OF SAID YOKE SOCKET AND A KEYPIECE SLOT EXTENDING THERETHROUGH, SAID KEYPIECE SLOT HAVING DIVERGENT SURFACES MATCHING THOSE OF SAID KEYWAY SLOTS AND ALIGNED WITH SAID KEYWAY SLOTS WHEN SAID YOKE IS RECEIVED IN SAID YOKE SOCKET; A KEYPIECE EXTENDING THROUGH THE KEYPIECE SLOT AND OUTWARDLY ON EITHER SIDE OF THE YOKE TO BE RECEIVED IN SAID KEYWAY SLOTS, SAID KEYPIECE HAVING DIVERGENT SURFACES MATCHING SAID KEYWAY AND KEYPIECE SLOTS; AN OPERATING COIL MOUNTED ON SAID FRAME; AND A MAGNETIC ARMATURE IN FACING RELATION TO SAID YOKE FOR OPERATION THEREWITH IN RESPONSE TO SAID COIL.