US3928831A

US3928831A - Coil and solenoid incorporating same

Info

Publication number: US3928831A
Application number: US526073A
Authority: US
Inventors: Kenji Yatsushiro; George F Kuchuris; John Willigman
Original assignee: Controls Company of America
Current assignee: Eaton Corp
Priority date: 1974-11-22
Filing date: 1974-11-22
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: GB1481747A; JPS5547049Y2; DE7536819U; JPS5167355U; CA1041150A

Abstract

The coil bobbin has a terminal support integral with one end flange. The terminals are inserted into the terminal slots in the support after the wire is wound on the bobbin. The slots are tapered so the terminal end which passes through the slot must be forced and a seal around the terminal results. The seal prevents leakage past the terminal when the coil is encapsulated. The bobbin interior forms a core guide and the bobbin includes projecting integral guides for the solenoid core, thus eliminating the usual metal guides. One side flange of each guide is cut back to receive a tang of a metal bracket. The tang serves to hold the core in place and projects into the groove on the side of the core to function as a core stop when the end of the groove hits the tang.

Description

United States Patent [191 Yatsushiro et al.

[ Dec. 23, 1975 COIL AND SOLENOID INCORPORATING SAME [73] Assignee: Controls Company of America,

Schiller Park, 111.

[22] Filed: Nov. 22, 1974 [21] Appl. No.: 526,073

3,530,572 9/1970 Conrath 335/248 X 3,566,322 2/1971 Horbach 3,593,240 7/1971 Garcznski 335/249 Primary Examiner-G. Harris Attorney, Agent, or Firm-Michael, Best & Friedrich [57] ABSTRACT The coil bobbin has a terminal support integral with one end flange. The terminals are inserted into the terminal slots in the support after the wire is wound on the bobbin. The slots are tapered so the terminal end which passes through the slot must be forced and a seal around the terminal results. The seal prevents leakage past the terminal when the coil is encapsulated. The bobbin interior forms a core guide and the bobbin includes projecting integral guides for the solenoid core, thus eliminating the usual metal guides. One side flange of each guide is cut back to receive a tang of a metal bracket. The tang serves to hold the core in place and projects into the groove on the side of the core to function as a core stop when the end of the groove hits the tang.

6 Claims, 14 Drawing Figures US. Patent Dec. 23, 1975 Sheet 1 Of2 3,928,831

COIL AND SOLENOID INCORPORATING SAME BACKGROUND OF THE INVENTION In manufacture of solenoids of the general type shown herein the art has adopted the encapsulated coil as a standard in high volume production. Encapsulated coils are cheaper and better. Prior coil designs, however, have used separate bridges to support the terminals and have required three or more mold sections (with resultant high cost) or tape wrapped with undesirable cost penalties. Further, the prior designs have required core guides inside the bobbin which used costly metal parts and increased the wire-to-core gap with consequent reduction in magnetic coupling.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coil design which completes the magnet wire termination with minimal labor and parts while providing firm support for the terminals. Another object is to design the coil bobbin to permit high pressure encapsulation with a 2-section mold while avoiding flash on the tenninals. These objectives are achieved by the design described above which supports the terminals on a bobbin flange extension and seals and grips the terminals to prevent flash and pull-out of the terminals.

Another object is to eliminate the customary core guides. This is accomplished by molding the bobbin with integral guide extensions. As a consequence the magnetic coupling is closer and the working force is increased or for the same force less wire is required.

A final object is to provide a solenoid construction incorporating the coil and providing a core stop which also retains the core in the assembly. This is accomplished by providing a tang which projects from a bracket through a cutout in the bobbin guide flange into a goove on the core while the bracket retains the coil.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the bobbin.

FIG. 2 is a fragmentary plan view of the terminal end of the bobbin.

FIGS. 3 and 4 are, respectively, horizontal and vertical sections through the terminal slots of the bobbin.

FIG. 5 is a perspective of the bobbin after winding and mounting the terminals.

FIG. 6 is a fragmentary horizontal section showing the manner in which the terminal is mounted in the slot.

FIG. 7 is a vertical section showing the terminal mounted in the slot.

FIG. 8 is a top plan view of the encapsulated coil.

FIG. 9 is a side elevation of the encapsulated coil.

FIG. 10 is an end view of the encapsulated coil.

FIG. 11 is a section through the coil taken on line llll in FIG. 10.

FIG. 12 is a plan view of the core.

FIG. 13 is a side elevation of the core.

FIG. 14 is a plan view of the assembled solenoid.

DESCRIPTION OF THE PREFERRED EMBODIMENT The bobbin 10 is spool-like in appearance with a smooth, generally rectangular central bore 12 and has guide channels 14 projecting from one end to extend the core guiding surface. It 'will be noted that each guide channel has side flanges l6 and one corner of the flange is cut out at 18 to receive the core stop tang as will appear more fully hereinafter. The bobbin has

end flanges

20,22 between which the magnet wire is wound. The larger flange 20 projects upwardly and flares outwardly and includes thickened portions 24 through which slots are provided to receive terminals. As can be seen in FIGS. 3 and 4, these slots are tapered inwardly towards the wire side of the flange. Thus in FIG. 3 there is a rounded entry into the slot 26 and the slot tapers inwardly from the entry. As can be seen in FIG. 4, the slot in vertical section has a straight portion leading to a rather abrupt inward taper at the wire side of the slot. Thus when the terminal 28 is pressed in from the outside, the small portion 30 of the terminal must be forced into the slot and it achieves a good mechanical fit while sealing the terminal relative to the end flange 20. This seal prevents the encapsulating material from being forced out along the terminal and getting onto the spade portion of the terminal which would require handwork to clean up the terminal.

Magnet wire 34 is wound on the bobbin and then the terminals are pressed in from the outside, as in FIG. 5.

Then the magnet wire is mechanically connected to the slots 32 in the terminal end and preferably then soldered or welded. The coil is now ready for encapsulation and a 2-part or section mold is clamped onto the end flange of the bobbin securely enough to permit high pressure injection or transfer molding. The encap-..

sulant covers the wire 34 completely and locks onto the flanges as may be seen in FIG. 11. Thus the perimeter of each flange is slightly reduced at 36 so the encapsulant can flow slightly over the end of the flange. The portion adjacent the tenninals is molded with the incline 38 and the flares 40. This completely encloses the terminals on the inside. This locks the terminals in the assembly and there is no danger of terminal pull-out.

The solenoid core is designated by reference numeral 42 and comprises a stack of laminations 44 with the outside of the stack on each side having a heavier piece of metal 46 running down the length and then bent in at one end to provide the connection point for the device to be actuated. It will be noted that a groove 48 is provided on each side of the core. This groove is to receive the core stop tang, as will appear hereafter.

The solenoid has a C-frame 50. The laminations on the closed end of the frame are formed so as to provide a projection 52 into the center of the coil which serves to center the end of the bobbin in the frame. The coil is placed in the C-frame after shading coils 54 are positioned in place. Then the kickout springs 56 are positioned in the assembly, the core is put into the coil and the coil stop members 58 are riveted into place. It will be noted that the stops 58 are formed to provide a channel-like portion 60 which cooperates with the extending plastic core guide to reinforce the core guide. Also each stop has a tang 62 which projects through the cutout comer 18 of the guide and into the groove 48 on each side of the core. The bracket holds the coil relative to the frame and'the tang cooperates with the inboard end 64 of the groove to limit outward movement of the core.

It should be noted each of the two guides has side flanges which guide the stem of the core in one direction while the flat of the guides guide in the other direction. The guides obviously could be one tubular member. Therefore, in the claims the use of the term guides is meant to embrace a tubular guide since it has plural guide surfaces. The advantage of the channel-like guides (beyond using less material) resides in the fact the space between the flanges on each side can accept and permit use of the shoulders 66 under the head 68 of the core. These shoulders increase the pull of the solenoid at the stage of travel where pull normally drops off (see US. Pat. No. 2,468,052). The channel guides obviously are not as strong as a tubular guide would be. But the brackets 58 closely embrace the guides on all sides and reinforce the guides.

By way of recapitulating some of the advantages of the present construction, it will be noted that the metal core guides heretofore employed in solenoid manufacture have been eliminated and the wire, therefore, is closer to the iron of the core. This means there is closer magnetic coupling which develops a greater working force for the same coil winding, or for the same working force the amount of copper wire can be reduced. There is minimal amount of labor involved in winding the coil and assembling the terminals since there are no separate pieces to be handled insofar as providing bridges and the like for the terminals. Furthermore, the method of mounting the terminal into the bobbin flange insures against any flash on the terminals which would require hand cleanup. The coil is designed to be molded in a 2-part mold which inherently results in the least cost of manufacture of the mold and also requires minimal maintenance. There is no need to design the mold to seal around the terminals. The terminal insertion in the flange provides a complete seal against the encapsulating material working along the terminals during the high pressure encapsulating process. Finally, in the assembly of the solenoid the brackets hold the coil in position while the core stops provide a simple and effective means for controlling core withdrawal.

We claim:

1. A coil comprising a coil bobbin having a spool-like central portion and a flange on each end of the central portion,

a wire wound on the central portion of the bobbin,

one of the flanges being extended and being provided with two terminal receiving slots located beyond the depth of the wire wound on the spool with each 5 slot being tapered in both directions from the outside of the flange towards the spool side of the flange,

a terminal mounted in each slot and sized to require a sealing force-fit between the terminal and the extended flange,

the ends of the wire being connected to said terminals,

encapsulating material surrounding the wire and the inside ends of the terminals,

integral opposed guides projecting beyond the central portion of the bobbin with the inside surfaces of the guides being aligned with and forming a continuation of the inside surface of the bobbin, each guide having three guiding surfaces.

2. A solenoid having a frame, a core and the coil according to claim 1,

said core being guided in the bobbin and guides and having a groove along one side,

and a bracket connected to the frame and including a tang projecting into said groove to act as a limit stop when the end of the groove strikes the tang.

3. A solenoid according to claim 2 in which the tang engages the guide to retain the core.

4. A solenoid according to claim 3 in which each guide is channel-like and a bracket fits over each projecting guide to reinforce the guide.

5. A solenoid according to claim 4 in which the side flange of the guide is cut away to receive the tang.

6. A solenoid according to claim 5 in which the confronting side flanges of the channel-like guides are spaced far enough to permit passage of an enlarged section of the core stem.

Claims

1. A coil comprising a coil bobbin having a spool-like central portion and a flange on each end of the central portion, a wire wound on the central portion of the bobbin, one of the flanges being extended and being provided with two terminal receiving slots located beyond the depth of the wire wound on the spool with each slot being tapered in both directions from the outside of the flange towards the spool side of the flange, a terminal mounted in each slot and sized to require a sealing force-fit between the terminal and the extended flange, the ends of the wire being connected to said terminals, encapsulating material surrounding the wire and the inside ends of the terminals, integral opposed guides projecting beyond the central portion of the bobbin with the inside surfaces of the guides being aligned with and forming a continuation of the inside surface of the bobbin, each guide having three guiding surfaces.

2. A solenoid having a frame, a core and the coil according to claim 1, said core being guided in the bobbin and guides and having a groove along one side, and a bracket connected to the frame and including a tang projecting into said groove to act as a limit stop when the end of the groove strikes the tang.