Note: Descriptions are shown in the official language in which they were submitted.
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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 ob;ect 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 terminals. These objectives are
achieved by the design described above which ~upport~ the
terminals on a bobbin flange extension ant seals and grips
the terminals to prevent flash and pull-out of the terminals.
Another ob;ect 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
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cutout in the bobbin guide flange into a groove on the core
while the bracket retains the coil. - '
The invention relates to 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 e~tended 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 bo'th directions from the outside o~ 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 the 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 form-
ing a continuation of the inside surface of the bobbin, each
~uide having three guiding surfaces.
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DESCRIPTION OF THE DRAWI~GS
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 slot~ 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 ;~
' 30 mounted in the slot.
Fiq. 8 is a top plan view of the encap~ulated coil~
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Fig, 9 is a side elevation of the encapsulated coil. ' '
Fig. 10 LJ an end view of the encapsulated coil.
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Fig. 11 is a section through the coil taken on
line 11--11 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
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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 16 and one corner of the flange is cut out ;~
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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 orced 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 i8 mechanically connected to the ~lots
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 encapsulant co~ers 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 terminals is molded with the incline
38 and the flares 40. This completely encloses the terminals
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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 a2 and comprises a stack of laminations 44 with theoutside 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 wili be noted that tlle
5, stops 58 are formed to provide a channel-like portion 60
s 20 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 corner 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 no~ed each of the two guides has
side flanges which guide the stem of the core in one direc-
tion while the flat of the guides guide in the other (90~)
directio~. The guides obviously could be one tubular member.
Therefore, in the claims the use of the term "guides" is
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meant to embrace a tubular guide since it has plural gui~e
- 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 U.S. Patent No.
2,468,052, issued April 26, 1949 in the name of H. Y. FisherJ
m e 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
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coupling which develops a g~eater 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
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involved in winding the coil and assembling the terminals
: since there are no separate pieces to be handled insofar as
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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 whlch 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
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terminal insertion in the flange provides a complete seal
~ against~ the encapsulating material working along the termin-
als during the high pressure encapsulating proces~. Finally,
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-~ the assembly of the solenoid the brackets hold the coil in
position while the core stops provide a simple and effective
m~an~ ior controlling core withdrawal.
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