US3621421A

US3621421A - Solenoid having improved backstop

Info

Publication number: US3621421A
Application number: US883509A
Authority: US
Inventors: Louis R Conrath
Original assignee: Detroit Coil Co
Current assignee: Detroit Coil Co
Priority date: 1969-12-09
Filing date: 1969-12-09
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

An industrial type AC solenoid comprising a stator having its laminations and sideplates riveted together as an integral assembly, and provided with a backstop member which absorbs the impact of the return stroke of the plunger, and which is readily connected in interlocking engagement with the sideplates of the stator, after the coil and plunger are inserted, by sliding the backstop between the sideplates.

Description

United States Patent 1 1111 3,621,421

[72] inventor Louis R. Conrath [56] ReferencesCited IN 3323? UNITED STATES PATENTS Q Dec9 1969 2,459,073 1/1949 Jeffrey 335/257 [45] Patented Nov'16l97l 2,877,390 3/1959 Trombetta... 335/257x [73] Assignee mmucoucompmy 2,665,397 1/1954 jencts gig/257 Femdakmch 2,671,!87 3/1954 encs /257 conunmmndmpmohppucauon sum 3,501,724 3/1970 Westphal 335/248 726,291, May 3, 1968. Primary Examiner-G. Harris Attorney-.- Burton and Parker [54] SOLENOID HAVING IMPROVED BACKSTOP ABSTRACT: An industrial type AC solenoid comprising a sta- 18 Claims Drawing Figs tor having its laminations and sideplates riveted together as an [52] [1.8. CI 335/257, integral assembly, and provided with a backstop member 335/257, 335/277 which absorbs the impact of the return stroke of the plunger,

[51] Int. Cl 1101: 7/12 and which is readily connected in interlocking engagement [50] Field of Search 335/248, with the sideplates of the stator, after the coil and plunger are 257, 277 inserted, by sliding the backstop between the sideplates.

PAIENTEBunv 1618?! 3,521,421

SHEET 1 [IF 4 L INVEN TOR \JG .100/3 6 Comewzw 30 ATTORNEYS PATENTEnuuv 15 I97! SHEET 2 BF 4 INVENTQR ATTORNEYS PATENIEBuuv 16 Ian 3.621.421

v sum 3 or 4 6 INVENTOR 100/5 A. (ON/64TH BY ATTORNEYS PATENTEnuuv 16 mm SHEET 1+ 0F 4 INVENTOR 100/6 A. CON/94TH ATTORNEYS SOLENOID HAVING IMPROVED BACKSTOP This application is a continuation-in-part of application Ser. No. 726,291, filed May 3, 1968.

BACKGROUND OF THE INVENTION The present invention relates particularly, though not exclusively, to industrial solenoids and more particularly to improvements in solenoids of the type illustrated and described in US. Pat. Nos. 2,671,187 and 2,665,397 of common ownership herewith. Such patents show a well-known push-type industrial solenoid wherein a T-shaped plunger is operatively associated at the end opposite its head with a pushpin for shifting the valve or other device to be actuated when the solenoid is energized. This type solenoid is provided with a backstop for absorbing the shock and limiting outward movement of the plunger when the solenoid is deenergized. The backstop is carried by a pair of sideplates secured to opposite sides of the stator, the construction being such that assembly of the backstop to the stator requires the sideplates to be bolted to the stator after the backstop is connected to the plates.

The present invention has for its general object the provision of an improved solenoid wherein the major components are detachably secured together into an operative unit though the sideplates are permanently, i.e. nonremovably, secured to the stator prior to assembly of the coil, plunger and backstop with the stator.

A related object is to provide a solenoid of the above character the components of which are assembled in and maintained in proper operating condition and position relative to each other by the components themselves.

Another object is the provision of a solenoid wherein the sideplates for supporting the backstop and the laminations comprising the stator may be secured together at the same time in one operation and by the same fastening means, such that the sideplates become and remain an integral part of the stator structure, and wherein the backstop and sideplates are so designed that the backstop may be inserted in position between the sideplates and is self-locking in its operative position.

Another object is the provision of an improved solenoid construction wherein the backstop may be assembled in selflocking operative relation with the sideplates by resilient elements between the sideplates and backstop which also serve to absorb the shock of impact of the plunger against the backstop.

A further object is the provision of a solenoid wherein the coil, plunger, and backstop are held in operative relation by an interfitting self-locking relation of such parts with themselves and the stator structure.

Another object is to provide a solenoid type of electromagnet having a plunger backstop member and a magnetizing coil either or both of which may be readily removed from the solenoid assembly without disassembly of the stator frame structure thereof.

SUMMARY OF THE INVENTION ing across 'the path and limiting outward movement of the plunger. The backstop is slidably endwise inserted in the space between the ends of the sideplates. The coil is wound on a bobbin having a skirt portion which cooperates with depending marginal portions of the backstop to retain the coil against dislodgment from the core structure. lnterposed between angularly disposed marginal edges of the sideplates and underlying marginal portions of the backstop is a pair of strips or pads of elastomeric material, which are received in retaining pockets and serve to absorb the shock of the plunger impacting against the backstop on the return stroke thereof. Each of the pads has a yieldable tab thereon projecting into a notch formed in the marginal edge of a cooperating portion of the assembly for retaining the backstop against dislodgment from the assembly.

The disclosed solenoid is assembled by first permanently securing the sideplates and the laminations comprising the stator. The coil is next received in an aperture provided in the stator and sideplates. The plunger is then received in the coil, from above, in a direction generally perpendicular to the direction of receipt of the coil in the stator. Finally, the backstop is received beneath a downwardly facing portion of the sideplates, above the plunger, in a direction generally perpendicular to the direction of receipt of the coil and the plunger, and is locked in place by the yieldable tabs on the shock-absorbing pads.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevation view with parts broken away of a solenoid construction in accordance with the present invention;

FIG. 2 is a side elevation view taken in the direction 2-2 of FIG. 1;

FIG. 3 is an exploded perspective view of the several components of the solenoid substantially as shown in FIGS. 1 and FIG. 4 is a cross-sectional side view of the upper portion of another embodiment of the solenoid of the invention;

FIG. 5 is a partial side elevation of the solenoid embodiment shown in FIG. 4;

FIG. 6 is an end elevation with parts broken away of a modified form of the solenoid of FIGS. 1-5;

FIG. 7 is a side elevation taken in the direction of 7-7 of FIG. 6; and

FIG. 8 is an exploded perspective view of components of the solenoid of FIGS. 6 and 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention as illustrated in the various FIGS. of the drawings is an industrial-type solenoid, the major operating elements of which include a magnetic stator or core-frame structure 10, a field-coil unit 60, and an armature in the form of a reciprocating T-shaped plunger that is magnetically attracted to the core by the magnetic field produced therein by the coil.

The stator-frame structure comprises a hollow rectangular stack 12 of soft iron laminations, which are held in alignment and are secured together by rivets 14 extending transversely through the stack. As shown in FIG. 3, the laminations are of substantially C-shaped configuration defining in the stack a centrally located rectangular coil-receiving aperture 16 and a narrow channel or plunger-receiving slot 18 communicating at one end with the aperture. In the depicted orientation of the stack, the slot 18 opens upwardly between overhanging

stator arms

13 and 15 through the upper end of the hollow-core structure, between the

pole faces

17 and 19 of the overhanging arms, with the bight portion 24 of the stack located at the lower end of the core-frame structure opposite slot 18. Aperture 16 and slot 18 extend transversely of the stack and open through opposite sides thereof.

Mounted on opposite sides of the stack of laminations, and forming a part of the stator, is a spaced pair of upwardly extending sideplates 26-26, each including an aperture and slot therein of configuration similar to and aligned with the aperture 16 and slot 18 in the core stack. The sideplates are assembled with the core stack as a unit by the same rivets 14 that are employed to secure the laminations of the core stack. This expedient not only eliminates the use of separate fastening members for securing the sideplates to the core structure, but also avoids additional holes in the stack that would be required for such fastening members. In prior art industrial-type solenoids having a backstop, the sideplates were secured to the stator as shown in US. Pat. No. 2,665,397. The holes in the stator through which the fasteners extend to secure the backstop sideplates interferred with the magnetic field in the stator and increased the magnetic resistance thereof.

As indicated in FIG. 2, the bight portion of the stack has a centrally located hole 28 therein that extends downwardly therethrough and contains the upper end of a bushing 30 therein. Bushing 30 is adapted to receive a push rod or pin (not shown) for operative association with the solenoid plunger, and extends through aligned central openings provided in a cushioning pad 32, a mounting baseplate 34, and a retaining strap 36. Intermediate the ends of the bushing is an annular flange or collar 38, which is integrally formed thereon and is captured between the mounting baseplate 34 and the bottom of the stator within an opening in the pad 32.

The stator is placed on the resilient cushioning pad, which is formed of a piece of rubberlike or other elastomeric, yieldable material and is interposed between the core stack and an upstruck central portion 40 of the baseplate. The stator is detachably secured to the pad and baseplate by means of a spring-retainer strap 36 which holds the cushioning pad 32 firmly in place under slight compression. The strap 36 passes under the upstruck portion of the baseplate and extends upwardly about the core stack, the upper end of which has a pair of laterally spaced, transversely extending grooves therein in which the tumed-over upper ends of the spring strap are detachably received. As shown in FIG. 3 the marginal portions on the opposite sides of the raised central portion 40 of the baseplate 34 extend beyond the faces or sides of the core stack to provide a pair of mounting feet 46-46, each of which has a pair of apertures 48-48 therein for attaching the solenoid to a suitable support.

The field coil unit 60 comprises a coil bobbin 62 and a coil winding 64 and is removably received in the central aperture 16 and aligned slot 18 in the core structure, which embraces the coil.

The coil bobbin 62 is a sleevelike member formed of molded insulating plastic material, such as heat-stabilized nylon, having a central passage 63 extending axially therethrough and having a pair of axially spaced

flanges

66 and 68 integrally formed thereon. The passage opens through the opposite ends of the bobbin, which is of rectangular shape or cross section conforming to the shape and size of the transverse slot or passage in the core stack. The flanges are of flat rectangular shape and are contained in spaced planes normal to the longitudinal axis of the liner, imparting a spoollike configuration thereto. The marginal edges of the flanges extend beyond the walls of the centrally located sleeve to form the coil-retaining rims of the bobbin spool.

The coil 64 is wound in layers on the bobbin and is confined between the spaced flanges thereof. After the opposite ends of the winding are electrically connected to a pair of pigtail leads 70-70, which serve to facilitate connection of the solenoid coil in an energizable circuit from an external source of electrical power, the bobbin and coil may be suitably potted or an insulating tape covering may be wrapped about the exterior of the coil.

The field-coil unit is slidably inserted into the stator in a direction transversely thereof from either side of the frame structure and extends through and beyond the sideplates on the opposite sides thereof. As shown in FIG. 2, the coil is confined in the other two directions of its expanse by the'walls of the core stack that bound or define the aperture 16 in which the coil unit is received. Flange 66 is located at the lower end of the bobbin, shown resting on the upper side of the bight portion 24 of the core stack. The other or upper end of the bobbin projects axially upwardly beyond the upper flange 68 to form a rectangular skirt having a pair of laterally extending end walls 72-72 and a pair of longitudinally extending sidewalls 74-74 and is received in and extends through the plunger aligned slot 18 in the stator.

The two longitudinally spaced-apart end walls 72-72 of the skirt portion of the coil liner extend above the upper end of the core stack and are reinforced by laterally spaced-apart web portions 76-76, bracing the walls 72-72 against the upper flange 68. The two longer or longitudinally extending, laterally spaced-apart sidewalls 74-74 of the bobbin skirt portion extend a lesser distance above or beyond the upper flange 68 than the end walls 72-72 and terminate slightly below the pole faces 17 and 19. Risers, one of which is shown at 78, extending along the longitudinal direction of the upper flange 68 on opposite sides of the coil aperture 63 and integrally formed on the outer surface thereof, abut against the underside of the overhanging

arms

13 and 15 of the stator spacing the flange slightly therefrom.

Armature 80 constitutes the movable part of the solenoid and comprises a reciprocating plunger formed of a multiplicity of thin laminations of magnetic material which are riveted together. The plunger is shown as T-shaped having a shank or stem portion 82 and a widened crosshead portion 84. The stem is of rectangular cross section and is received internally axially of and within the central passage 63 of the coil sleeve after the coil unit has been inserted in the core-frame structure. The passageway 63 in the bobbin, in conjunction with a passageway liner, not shown, guides the armature for reciprocating movement.

Energization of the solenoid coil attracts the plunger downwardly to strike the underside of the crosshead portion against the pole faces 17 and 19 of the stator, the shock or impact against which is absorbed by the aforementioned cushioning pad 32. Upon deenergization of the solenoid, the plunger is returned, as by a spring (not shown) associated with the pushpin or structure actuated by the solenoid, and impacts against the yieldable backstop 90, which is located above the core stack and across the path of the plunger.

The embodiment of the backstop illustrated in FIGS. 1 to 3 includes a stop plate slidably inserted and retained between the upper ends or extensions of the sideplates 26-26, beyond the slotted end of the core stack. The sideplates are displaced outwardly from opposite sides or faces of the core stack, and receive the similarly configured stop plate in the expanded space defined between the outwardly inclined portions 50- 50 (FlG. 3) or 103-103 (FIG. 1), upwardly extending sidewall portions 52-52 and inwardly turned upper marginal edges 54-54 provided on each of the sideplates. It will be noted that the outward inclination 50-50 is slightly different than the inclination 103-103, but other than this the sideplates of FIGS. 1 and 3 are the same. An elongated relief opening 56-56, communicating with the slot 18, is provided in the inclined portion 50-50 of each of the sideplates to aceommodate insertion of the extension of the bobbin skirt portion above the upper end of the core stack, and to provide sufficient clearance for the plunger to prevent the lower corners of the crosshead thereof from striking against the inclined portions of the sideplates. The inturned marginal edges 54-54 of the sideplates are centrally notched as shown at 58-58 to fonn a catch cooperating with an upwardly projecting extended portion of a shock-absorbing cushioning pad 1 10; one of which is carried on each side of the stop plate. In addition to their shock-absorbing functions, the shock pads serve to hold or lock the stop plate in place between the sideplates, as later described.

The backstop member 90 is an inverted generally U-shaped element formed or molded of a piece of plastic insulating material and includes a flat rectangular central web or bight portion 92 bridging a pair of laterally spaced, longitudinally ,extending leg portions 94-94 depending from the central bight portion. As shown in FIGS. 1 and 2, a centrally located aperture 96 extends transversely through the bight portion. the underside of which has a centrally located rectangular cavity 98 formed therein between the longitudinally spaced ends 97-97 and the laterally spaced depending legs 94-94. The cavity conforms to the shape of the crosshead of the plunger which is guidingly received therein on the return stroke thereof. The opposite longitudinally extending, upper marginal edges of the bight portion of the backstop member are relieved to form a step or shoulder 100-100 spaced from and underlying the inturned marginal edges 54-54 of the sideplates 26-26.

The depending leg portions 94-94 of the backstop member extend in juxtaposed position to, and span the distance between the upwardly extending sidewall portion 50-50 and and 52-52 of the sideplates. The lower ends of the leg portions 94-94 conform generally to the contour of the jogged or inclined sideplate portions 50-50 which underlie the leg portions and vertically support the stop plate in the depicted orientation of the solenoid.

In accordance with one aspect of the invention, the leg portions ofthe stop plates are relieved as shown at 102-102 on the inwardly facing sides thereof to receive the extended end walls 72-72 of the coil bobbin skirt portion in the assembled condition of the solenoid. Additionally, the outwardly facing sides of each of the leg portions are relieved inwardly to form an open-faced shallow pocket, one of which is shown in FIG. 3 at 104, between the longitudinally displaced ends thereof, for receiving a corresponding one of the aforementioned shock pads 110.

The shock pads 110 are formed of narrow resilient strips of elastomeric material of rectangular cross section, and have a thickness approximately equal to the width of the land portions forming the walls of the pockets 104. The lower side and opposite ends of each pad conform to the generally U-shaped configuration of the pockets, which are closed on three sides, including the lower side and the longitudinally displaced ends thereof, and retain the shock pads endwise therebetween. The upper side of each pad projects above the stepped shoulder portion 100 of the stop plate to abut the underside of the inturned edges 54 of the sideplates. The pads leave a series of longitudinally displaced, upwardly extending sinusoidal or scallop-shaped projections 112 formed thereon, of which a centrally located one, 114 of the projections extends above the other projections, and is formed with substantially straight sides as shown.

After the pads are inserted in their corresponding pockets, the stop plate is slidably inserted endwise between the outwardly displaced upper ends of the sideplates 26-26 of the core-frame structure. The scallops 112, and extended projection 114 of the pads, are compressed by the overhanging mar ginal edges 54-54 of the sideplates and by the application of a slight downward pressure on the stop plate during insertion thereof, displacing the material of the respective pads longitudinally and laterally inwardly thereof to partially occupy the space or valleys between the scallops. When the stop plate is fully inserted between the sideplates, the compressed central projection 114 of each of the shock pads is aligned with its corresponding notch 58 in the inturned upper marginal edges 54-54 of the adjacent sideplates, and is released to expand upwardly therethrough with its sides abutting in interlocking engagement against the sidewalls of the notch 58, so as to catch and prevent dislodgment of the stop plate from the sideplates.

As shown in FIG. 1, the end walls 72-72 of the bobbin skirt portion extend above the lower ends of the depending leg portions 94-94 of the backstop member, and are slidably engageably received between and are embraced by the inwardly facing sides 102-102 of the leg portions of the backstop member, to retain the coil unit in place in and against transverse movement relative to the stator. As a result of the described construction, the stop plate is retained against dislodgment between the sideplates of the core'frame structure and firmly secures the coil unit in proper operating position in and against dislodgment from the stator.

The method and sequence of assembling the solenoid is illustrated in FIG. 3. The sideplates 26 are first permanently secured to the laminations comprising the stator by rivets 14, or the like, as described hereinabove. The field coil 60 is next received in the rectangular aperture 16 defined in the stator l0 and sideplates 26, in the direction of arrow 61 or from the opposite side. The armature plunger 80 is then received in the slot 18 in the stator 10, from above the stator, in the direction of arrow 81, which is perpendicular to the direction 61 of receipt of the field coil in the stator. Finally, the backstop plate 90 is slid endwise between the inturned marginal edges 54 of the sideplates, and the pole faces 17, in the direction of arrow 91, and locked in place by the pads 110 as described hereinabove. The pads are inserted in the pockets 104 prior to assembly of the backstop. It should be noted that the backstop plate 90 must he slid in a direction perpendicular to the direction of assembly of both the armature plunger 80 and the field coil 60, which substantially eliminates assembly errors and provides an exceptionally secure assembly. Further, the sequence insures proper assembly, as each part interlocks with the other.

The embodiment of the industrial solenoid shown in FIGS. 4 and 5 is similar to the embodiment of FIGS. 1 to 3, except that the marginal edges 154 of the sideplates 126 in FIGS. 4 and 5 are turned outwardly, and the backstop plate 190 is slid endwise over the marginal edges. The pad-receiving pocket 204 is thus defined in the inside of the backstop plate, and the pad 210 is compressed between the lower edge of the pocket and the outer surface of the backstop marginal edge 154. The shock-absorbing pad may be provided with a central projection 214, which is received in a slot 158 defined in the edge 154 of the sideplates to lock the backstop in position, as described hereinabove. The remaining details of the embodiment shown in FIGS. 4 and 5 may be identical to the embodiment described hereinabove, and have been numbered in the same sequence. The method of assembly of the embodiment shown in FIGS. 4 and 5 is thus identical to the method of assembly described in regard to FIGS. 1 and 3.

The solenoid is comprised of a minimum number of parts, which are assembled into a compact structure without the use of tools and are held together in physical alignment and proper operating relationship by structural interlocking features of the components themselves without the use of additional fastening members. Disassembly of the solenoid structure is likewise facilitated, the coil and/or the backstop member being readily removable from the core assembly without disassembly of the core-frame structure.

In FIGS. 6-8 a modified form of the invention is shown. In this embodiment the stator laminations 12 are riveted together at four locations 14 between a pair of

riveting plates

150 and 152. Next the sideplates 26 are riveted to the stator in overlying relation to the riveting plates as at 154 and 156 by the rivets 158. Thereafter the coil, plunger, and backstop are assembled as previously described. The separate assembly of the sideplates to the stator has been found to increase solenoid life. The riveting plates are similar in shape to the stator laminations but are of thicker material than the laminations.

The shock-cushioning pads 162 as best shown in FIGS. 7 and 8 are of somewhat different construction than those previously described. Pads 162 have a series of scallop-shaped projections 164 along the lower edge, and a single projection 166 along the upper edge. Projection 166 is disposed directly opposite the central scallop 168 along the lower edge so that during endwise sliding assembly of the backstop between the sideplates, the pad will deflect downwardly beneath the projection 166 to permit deflection of the latter sufficient to allow the assembly.

The backstop 170 is generally similar to the backstop heretofore described. However, backstop is relieved at its upper surface as at 172 and reinforced by the ribwork 174. This results in material saving without sacrifice of needed strength.

By altering the dimension A of the backstop, as shown in FIG. 6, the stroke of the plunger may be varied to accommodate the requirement of the solenoid application.

As in the embodiment of backstop 90, backstop 170 includes a pair of longitudinal cavities or slots receiving the cushion pads 162. The sideplates are provided with a cavity or notch 178 which receives the projection 166 to lock the backstop and pads in place. Longitudinal surfaces 180 ride the inclined surfaces 182 of the sideplates to support the backstop and place the cushion pads 162 under preload compression against the inturned marginal edges 184 of the sideplates.

What is claimed is:

l. in a solenoid having a laminated coil-receiving stator with sideplates overlying opposite sides of the stator and having extensions lying beyond pole faces of the stator to carry a backstop for limiting movement of a solenoid plunger reciprocating between it and the pole faces of the stator, characterized in that: the laminations comprising the stator and the sideplates are riveted together in a permanently unitary assembly, the backstop is sized to bridge between the sideplate extensions, means interconnecting opposite sides of the backstop with the sideplate extensions for slidable introduction of the backstop parallel to the pole faces between the sideplate extensions and retaining the backstop in operative position under impacting of the plunger moving away from the pole faces, means for holding the backstop against slidable withdrawal from its aforesaid operative position, and said sideplate extensions including laterally extending marginal edges overlying portions of the backstop to retain the backstop under impacting of the plunger.

2. The solenoid defined in claim 1, characterized in that resilient shock-absorbing pads are disposed between the laterally extending marginal edges of the sideplate extensions and portions of the backstop and compressed therebetween.

3. The solenoid defined in claim 2, characterized in that the laterally extending marginal edges of the sideplates have a notch which receives an upstanding projecting portion of the resilient pads, retaining the position of the resilient pads and the backstop member.

4. The invention defined in claim 2 characterized in that the sideplates and backstop member are provided with opposed cavities and the resilient shock-absorbing pads have portions received in said cavities to retain the backstop against slidable withdrawal from between the sideplate extensions.

5. The solenoid defined in claim 2, characterized in that the marginal edges of the sideplate extensions are turned inwardly to overlie the stator and slidably receive the backstop member therebeneath, between the extensions of the sideplates.

6. The solenoid defined in claim 5, characterized in that the extension of the plates, adjacent the upper end of the stator, are inclined outwardly, and the backstop member has complementary downwardly facing tapered portions which are supported on the inclined portions of the sideplates.

7. The solenoid defined in claim 4, characterized in that said cavities in the backstop includes two longitudinally extending enclosed slots which receive the pads, and the sideplate extensions include notches, and each pad is received in one of the slots and includes a projecting portion extending into a notch in a sideplate extension.

8. In a solenoid having a laminated coil-receiving stator with sideplates overlying opposite sides of the stator and extending beyond it to carry a backstop plate for limiting outward movement of a solenoid plunger characterized in that: the backstop plate is sized to bridge between the sideplates for longitudinal slidable reception therebetween when the sideplates are rigidly secured to the stator, resilient shock-absorbing means interposed between the backstop plate and the sideplates for cushioning the shock of the plunger striking the backstop plate, and resistingly displaceable locking means including a portion of the resilient shock-absorbing means cooperable with the backstop plate and at least one sideplate for retaining the backstop plate in operative position between the sideplates and being resistingly displaceable to permit said longitudinal reception of the backstop plate between the sideplates.

9. In a solenoid having a laminated coilreceiving stator with sideplates overlying opposite sides of the stator and extending beyond it to carry a backstop plate for limiting outward movement of a solenoid plunger characterized in that: the backstop plate is sized to bridge between the sideplates for longitudinal slidable reception therebetween when the sideplates are rigidly secured to the stator, resilient shock-absorbing means interposed between the backstop plate and the sideplates for cushioning the shock of the plunger striking the backstop plate and entrapped in the backstop plate against displacement longitudinally thereof, and said shock-absorbing means including a resistingly displaceable portion interlocking with a portion of at least one of the sideplates to retain the backstop plate in operative position between the sideplates.

10. In a solenoid having a laminated coil-receiving stator with sideplates overlying opposite sides of the stator and extending beyond it to carry a backstop plate for limiting outward movement of a solenoid plunger characterized in that: The backstop plate is sized to bridge between the sideplates for longitudinal slidable reception therebetween when the sideplates are rigidly secured to the stator, a shock pad disposed between each opposite longitudinal edge of the backstop plate and an overlying margin of each sideplate and trapped against longitudinal movement in a pad-receiving pocket in one of the plates and having a projecting resistingly deflectable portion interlocked against longitudinal movement with a complementary portion of the other plate.

11. The invention defined by claim 10 characterized by the pad-receiving pockets being provided in the longitudinal edges of the backstop plate and being open toward the adjacent overhanging margin of the sideplate and closed at opposite ends.

12. The invention defined by claim 11 characterized in that the pads are each provided with a resistingly deflectable tab received in a notch formed in the adjacent sideplate.

13. A solenoid comprising: a stator of generally C-shaped configuration having a bight portion and arm portions overhanging the bight portion, a solenoid coil received in the stator between the bight portion and the overhanging arm portions; said coil having means defining a plunger guideway terminating in a skirt portion disposed between the arm portions of the stator, a pair of sideplates riveted to the stator and extending beyond the arm portions to carry a backstop in spaced relation from such arm portions, at least one such sideplate being notched to allow slidable reception of the coil transversely into the stator with the skirt portion passing through the notch, and a backstop cooperating with the sideplates for endwise slidable introduction between the sideplates in a direction perpendicular to the slidable reception of the coil, and said backstop having a depending portion overlapping said skirt portion of the coil preventing withdrawal of the coil from the stator.

14. The invention defined by claim 13 characterized in that both sideplates are notched and the backstop has depending portions embracing the skirt portion of the coil preventing withdrawal of the coil from the stator.

15. An electromagnet including a coil liner having a central passage extending therethrough, a coil winding, a reciprocating plunger having a head portion impacting against an end of the core frame and further having a shank portion extending through said end of the core frame into the central passage of the coil liner, a pair of plates secured to the opposite sides of the frame and extending beyond the said end of the core frame, said sideplates being oppositely inwardly turned at the ends thereof extending beyond the core frame and having a notch in each of the inturned ends thereof, a backstop plate received in the space between the said end of the core frame and the extensions of the sideplates and extending across the path of travel of the plunger in position to be struck thereby at one end of its stroke, said backstop plate having depending marginal portions underlying the inturned ends of the sideplates and a bounded pocket extending along and formed in each of the marginal portions thereof, and an elongate strip of resilient compressible material received in each of the pockets and engaging the inturned end of a sideplate, said strip having a compressible extended tab projection thereon received in releasable interlocking engagement with the notch in a corresponding sideplate to retain the stop plate against dislodgment from the core frame.

16. An electromagnet in accordance with claim 18 wherein the coil liner has a skirt portion extending through the said end of the core frame into the space between the depending marginal portions of the backstop plate embracing and receiving the skirt portion in interlocking engagement therewith and against dislodgment from the core frame.

17. In an electromagnet, a core structure having a central opening therein and a slot communicating with the opening and extending outwardly through one end of the core structure, a coil-bearing bobbin received in the central opening of the core structure and having a sleeve portion aligned with and extending through the slotted end thereof, a reciprocating magnetic plunger having a stem portion extending through said core structure into said bobbin-sleeve portion and further having a head portion impacting against the slotted end of the core structure, a pair of plates secured to the opposite sides of and extending beyond the slotted end of the core structure in the direction of reciprocation of the plunger and having backstop-retaining marginal edge portions, and a backstop plate received between the sideplates and extending across the path of travel of the plunger in position to be struck by the head thereof at the end of its retracting stroke, opposite marginal portions of the backstop plate depending therefrom and slidable between said sideplates beneath said backstop-retaining marginal edge portions and into locking frictional engagement with the extension of said bobbin-sleeve portion to prevent dislodgment of the coil-bearing bobbin from said core structure, and a body of resilient material positioned between each of said marginal portions of the backstop plate and the marginal edge portions of the sideplates.

18. An electromagnet in accordance with claim 17 wherein the outer end portion of each of the sideplates has a notch therein and the bodies of resilient material are retained endwise in the marginal portions of the backstop plate and have projecting yieldable tabs thereon one of which extends in the opposite direction from the others and is received in the notch in a corresponding one of the sideplates to retain the backstop plate against dislodgment from the sideplates.

pin-

November 16, 1971 Patent No. 3,621,421

Inventor-(s) Louis R0 Conrath It is certified that error appears in the above-ientified patent and that and Letters Patent are hereby corracteci as shown below:

In column 9, line 1) cancel numeral "18 anfi substitute 1n lieu thereof --15-'-.

Signed and sealed this 23rd day of MaylQfZZQ ROBERT GOTTSCHALK .cer Commissioner of Patents

Claims

1. In a solenoid having a laminated coil-receiving stator with sideplates overlying opposite sides of the stator and having extensions lying beyond pole faces of the stator to carry a backstop for limiting movement of a solenoid plunger reciprocating between it and the pole faces of the stator, characterized in that: the laminations comprising the stator and the sideplates are riveted together in a permanently unitary assembly, the backstop is sized to bridge between the sideplate extensions, means interconnecting opposite sides of the backstop with the sideplate extensions for slidable introduction of the backstop parallel to the pole faces between the sideplate extensions and retaining the backstop in operative position under impacting of the plunger moving away from the pole faces, means for holding the backstop against slidable withdrawal from its aforesaid operative position, and said sideplate extensions including laterally extending marginal edges overlying portions of the backstop to retain the backstop under impacting of the plunger.

9. In a solenoid having a laminated coil-receiving stator with sideplates overlying opposite sides of the stator and extending beyond it to carry a backstop plate for limiting outward movement of a solenoid plunger characterized in that: the backstop plate is sized to bridge between the sideplates for longitudinal slidable reception therebetween when the sideplates are rigidly secured to the stator, resilient shock-absorbing means interposed between the backstop plate and the sideplates for cushioning the shock of the plunger striking the backstop plate and entrapped in the backstop plate against displacement longitudinally thereof, and said shock-absorbing means including a resistingly displaceable portion interlocking with a portion of at least one of the sideplates to retain the backstop plate in operative position between the sideplates.