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Claims  |
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I claim:
1. A method of making a holder for a plurality of plug-in electrical
circuit protective devices for interrupting the flow of current flowing
therethrough, comprising the steps of:
(a) forming, from a blank of electrically conductive material, at least two
branches which are separated from each other by a spaced distance and
which are joined to a common trunk member, each of said branches having a
free end and two edges which join said free end to said trunk member;
(b) forming, along at least one edge of each branch of said blank, a pair
of spaced apart terminals which are adapted to removably receive the ends
of a common plug-in electrical circuit protective device;
(c) mounting said branches and said trunk of said blank on a generally flat
insulated base; and
(d) splitting each branch at a position intermediate its terminals to form
a plurality of severed branch portions and attached branch portions which
are carried by said insulated base, whereby those terminals of each
attached branch portion are joined to said trunk member and are connected
to each other to form a common electrical supply bus
(e) positioning an insulated member, on said base, to cover all but said
free end of each severed branch portion and at least part of said severed
branch portions and said trunk member of said blank, said insulated member
having at least one aperture therein of sufficient size to receive one
plug-in electrical circuit protective device; and
(f) aligning said insulated member to have said at least one aperture over
one pair of said spaced apart terminals.
2. A method of making a holder for a plurality of removable electrical
circuit protective devices, comprising the steps of:
(a) forming, from a blank of electrically conductive material, at least two
branches which are separated from each other by a spaced distance and
which are joined to a common trunk member, each of said branches having a
free end and two edges which join said free end to said trunk member;
(b) forming, along at least one edge of each of said at least two branches,
a pair of spaced apart terminals which are adapted to receive the ends of
a removable electrical circuit protective device;
(c) forming an electrical terminal at the free end of at least one branch;
(d) mounting said branches and said trunk of said blank on an insulated
base; and
(e) splitting each branch at a position intermediate its spaced apart
terminals such that two separated branch portions are formed,
whereby at least one spaced apart terminal remains joined to said trunk
member to form an electrical supply terminal and said electrical terminal
at said free end of said at least one branch is joined to only the other
spaced apart terminal on said at least one branch.
3. The method of claim 2, wherein before step (c) the following steps are
performed in any order:
(b1) forming at least one alignment aperture in each branch; and
(b2) forming at least one alignment aperture in said trunk member.
4. The method of claim 2, where in performing step (a) said branches are
formed generally parallel to each other and generally perpendicular to
said trunk member.
5. The method of claim 4, where in performing step (b) said terminals are
formed along non-adjacent edges of each branch and are formed generally
perpendicular to a plane of each branch.
6. The method of claim 2, wherein step (a) is performed by:
(aa) stamping a generally flat rectangular blank of metal, on at least one
side of a longitudinal reference line, to form a plurality of parallel
branches which are spaced apart from each other, each of said branches
being joined to a common electrically conductive trunk member in which
said reference line lies, each of said branches having marginal portions
defining a relatively short free end and two relatively long edges which
join said free end to said conductive base.
7. The method of claim 6, where in step (aa) said branches are formed to be
generally rectangular, are formed on two sides of said reference line, and
are formed generally at right angles to said reference line.
8. The method of claim 7, where in step (aa) said trunk member is formed to
be generally flat and rectangular and to have two short ends and two long
ends, said branches are formed along said long ends, and at least one
branch is formed at a location adjacent a short end; and further including
the step of severing from said trunk member said at least one branch which
is formed at a location adjacent said short end.
9. The method of claim 2, wherein step (b) is performed by:
(bb) forming, along one edge of each branch of said blank, a pair of
bifurcations which are adapted to receive the terminals of a plug-in fuse
of the type having pressure clip terminals, said bifurcations being
disposed generally at right angles to a plane of said blank and being
separated from each other by a predetermined distance generally equal to
the distance between said pressure clip terminals of said plug-in fuse.
10. The method of claim 9, where in step (a) at least two lateral branches
are formed on each side of a longitudinal reference line lying in said
trunk member; and where in step (bb) said bifurcations are formed along
nonadjacent edges of each lateral branch.
11. The method of claim 2, wherein step (b) includes the step of forming in
said least one branch a section of reduced width at a location
intermediate said spaced apart terminals;
wherein said insulated base has at least one aperture, and in step (c) said
one branch is mounted on said insulated base to have said one aperture
located under said section at reduced width; and
wherein step (e) is performed by die stamping said section of reduced width
at a position over said at least one aperture in said insulated base.
12. The method of claim 2, wherein step (a) includes the step of forming a
locating aperture adjacent the free end of at least one branch; and
wherein step (d) includes the step of positioning said locating aperture
over an insulated base having at least one upward projection located
thereon.
13. The method of claim 2, wherein said electrical circuit protective
devices are plug-in fuses having two spaced-apart downwardly disposed
blades; and wherein each terminal formed in step (b) comprises a pair of
spaced apart upwardly disposed bifurcations which are adapted to receive
said blades.
14. The method of claim 2, wherein prior to step (d) the following step is
performed:
(cc) forming an insulated base having a generally flat surface, having a
plurality of die stamping apertures and having aligning means for locating
said branches over said die stamping apertures of said base at a position
intermediate said spaced apart terminals.
15. The method of claim 14, wherein step (cc) includes the step of forming
a cover securing aperture in said surface of said insulated base; and
further including the step of:
(f) forming an insulated cover comprising a top wall having a plurality of
circuit protective device receiving apertures which are adapted to carry
protective devices therein, comprising a side wall which is joined to said
top wall and which has a tab which is adapted to be received in said cover
securing aperture in said insulated base, said cover securing aperture
being located in said insulated base so that said electrical terminal at
the free end of said one branch is exposed when said cover is joined to
said insulated base, and comprising a barrier wall which is joined to said
top wall and which is disposed between said insulated base and said top
wall and between said pair of spaced apart terminals when said cover is
joined to said insulated base.
16. The method of claim 15, wherein said step of forming aligning means in
said base is performed by forming a plurality of projections on said
surface of said insulated base; and
wherein the cover of step (f) is formed to have means for receiving said
projections to secure said electrical terminal at the free end of said one
branch between said cover and said insulated base.
17. The method of claim 2, wherein prior to step (d) the following step is
performed:
(cc) forming an insulated base having a plurality of die stamping
apertures, having a plurality of securing apertures therein, and having at
least one alignment projection for aligning said blank on said base to
have said die stamping apertures located intermediate the ends of said
terminals of each branch; and further including the step of
(f) forming a wall having attaching means for attaching said wall to said
securing apertures in said insulated base and having means for receiving
said one projection to secure said electrical terminal at the free end of
said one branch between said wall and said base.
18. The method of claim 17, wherein step (a) includes the step of forming
an alignment aperture in said blank; and
step (d) includes the step of locating said alignment aperture of said
blank to receive said alignment projection of said base.
19. A method of making a holder for a plurality of plug-in circuit
elements, comprising the steps of:
(a) forming, from a blank of electrically conductive material, at least two
branches which are separated from each other by a spaced distance and
which are joined to a common trunk member, each of said branches having a
free end and two edges which join said free end to said trunk member;
(b) forming, along at least one edge of each branch of said blank, one pair
of spaced apart terminals which are adapted to receive the ends of a
plug-in circuit element;
(c) mounting said branches and said trunk of said blank on an insulated
base;
(d) splitting each branch at a position intermediate its spaced apart
terminals such that two separated branch portions are formed, the terminal
of each branch portion which remains joined to said trunk member forming
common electrical supply bus terminals;
(e) positioning, on said base, an insulated member to cover at least part
of said trunk member and said branch portions, said insulated member
having a top and at least one wall which is joined to said top, said top
having at least one aperture located therein for receiving a plug-in
circuit element for one pair of said spaced apart terminals; and
(f) positioning said insulated member to have said at least one wall
disposed between the free end of at least one branch and that spaced apart
terminal which is joined to said free end such that said free end is
exposed.
20. The method of claim 19, wherein said insulated member includes a
plurality of tabs and said insulated base includes slot means aligned with
said tabs of said insulated member for attaching said insulated member
onto said insulated base; and further including the step of (g) inserting
said tabs into said slot means.
21. The method of claim 19, wherein said insulated member has a second wall
which is joined to said top at a location generally bisecting said at
least one aperture; and
step (e) includes the step of positioning said insulated member on said
base such that said second wall is located between said terminals of said
one pair.
22. A method of making a holder for a plurality of plug-in electrical
safety means for performing a fuse function, comprising the steps of:
(a) forming, from a blank of electrically conductive material, at least two
branches which are separated from each other by a spaced distance and
which are joined to a common trunk member, each of said branches having a
free end and two edges which join said free end to said trunk member;
(b) forming, along at least one edge of each branch of said blank, a pair
of spaced apart terminals which are adapted to receive the ends of plug-in
electrical safety means;
(c) performing the two steps which follow in any order:
(c1) forming at a predetermined location in said trunk member an aperture
to receive the threaded end of a threaded fastener, and
(c2) mounting the head of a threaded fastener on an insulated base such
that the threaded end of said fastener and at least part of said head are
exposed and said threaded fastener is not free to rotate relative to said
insulated base;
(d) mounting said branches and said trunk of said blank on said insulated
base with said threaded end of said threaded fastener passing through said
aperture in said trunk member and said part of said head in contact with
said trunk member; and
(e) splitting each branch at a position intermediate its terminals such
that two electrically separated branch portions are formed. |
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Claims |
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Description |
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TECHNICAL FIELD
This invention relates to holders for removeable circuit elements and fuse
blocks, in general, and to fuse blocks and holders for replaceable circuit
elements having blade-type terminals, in particular.
BACKGROUND OF THE INVENTION
Plug-in fuses are disclosed in U.S. Pat. No. 3,909,767 and 3,962,782. Such
a fuse comprises a plug-in fuse element which includes: a blade-like body
of fuse metal having a pair of laterally spaced terminal blade portions to
be received by pressure clip terminals in a mounting panel or fuse block;
current-carrying extensions at the inner end portions of each terminal
blade portion; and a fuse link portion, generally of reduced thickness and
small cross-sectional area, for interconnecting the current-carrying
extensions. These fuses are alternatively referred to as "ATC" fuses (ATC
is a registered trademark of Cooper Industries, Inc.) and have found
wide-spread use in electrical systems found in automobiles, motorboats and
other products.
Plug-in fuses are used in conjunction with pressure clip terminals which
are carried in a fuse mounting panel or by a fuse block. Generally
speaking such a panel or block comprises an insulated base to which are
attached pairs of terminals, each pair of terminals comprising a fuse
holder. Usually one side of each fuse holder is connected to a source of
power and the other side is connected to the electrical device which is
protected by the fuse. The terminals are, for the most part, individually
mechanically attached to the insulated base by rivets, screws, threaded
fasteners and the like. Sometimes, snap-in connections, pressure gripping
tabs, or heat staking is used to hold the fuse terminal on the base.
It can be appreciated from the foregoing description that the manufacture,
construction, and assembly of a fuse block, especially an ATC fuse block,
is difficult and labor intensive. Since the parts are small, a premium is
placed on the manual dexterity of the assembler. Thus, the manufacture of
ATC fuse blocks involves the use of semi-skilled workers. The use of
multiple, small, dimension sensitive parts also adds to the cost of
manufacturing a fuse block.
With the wide-spread acceptance of ATC fuses in mass produced products,
such as automobiles and pleasure craft, there is a need for a cost-saving
method of assembling a fuse block for plug-in fuses, a fuse block which is
easy to assemble, one which is easily adoptable to automated assembly, and
one which has fewer assembly steps.
SUMMARY OF THE INVENTION
In accordance with the present invention, a fuse holder and method of
forming a fuse holder is disclosed. Specifically, the fuse holder
comprises an insulated base, an electrical bus member carried by the base
and a plurality of fuse terminal members which were formed from the same
blank of metal as the electrical bus member and which were separated from
each other after that blank was mounted on the insulated base. The bus
member comprises a plurality of lateral branches joined to a common trunk
with each branch having at its free end one integral fuse accepting
terminal. Each fuse terminal member has, at one end, an electrical
terminal for receiving an electrical connection and, at an opposite end,
an integral fuse accepting terminal which is aligned to the free end of
one lateral branch. In one embodiment of the invention, the fuse holder
includes an insulated cover which is carried by the base and which has a
plurality of apertures which are aligned to the fuse terminals of each
branch so as to receive at least the ends of the fuse therein.
The fuse holder just described is preferably made by: forming from a
generally flat blank of metal a plurality of generally parallel branches
which are separated from each other by space distance; forming along one
edge of each branch a pair of pressure clip terminals which are adapted to
receive the blade portions of a plug-in fuse; mounting the formed blank of
metal on an insulated base; and severing each branch at a position between
the pair of pressure clip terminals, whereby those pressure clip terminals
of each branch which are joined to the trunk member form a common
electrical bus.
From the foregoing description it will be seen that the fuse holder can be
formed using a minimal number of steps makes economical use of material,
does not require highly skilled assembly workers, is adapted to automatic
manufacturing processes, and represents a cost-effective and improved
method of manufacture.
Numerous other advantages and features of the present invention become
readily apparent from the following detailed description of the invention
and the embodiments thereof, from the claims and from the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of the fuse holder that is the subject of present
invention:
FIG. 2 is a partial cross-sectional side view of the fuse holder of FIG. 1;
FIG. 3 is a partial cross-sectional end view of the fuse holder of FIG. 1;
FIG. 4 is a top plan view of the formed metal blank that is used in the
fuse of FIG. 1;
FIGS. 5 and 6 are partial side and partial side cross-sectional views of
one lateral branch of the blank of FIG. 4, as viewed along lines 5--5 and
6--6, respectfully;
FIG. 7 is an enlarged partial plan view of the threaded terminal at one end
of the fuse holder of FIG. 1, as viewed along line 7--7;
FIG. 8 is a partial perspective view of the threaded terminal of FIG. 7, as
viewed along line 8--8;
FIGS. 9 through 14 are pictorial representations of a sequence of steps
which, when performed, result in the assembly of the fuse block of FIG. 1;
FIGS. 10A, 14A, 15A through 15E, and 16 are representations of alternate
embodiments of various features of the invention:
FIG. 17 is a partial bottom plan view of the cover of the fuse holder of
FIG. 1; and
FIGS. 18A and 18B are partial perspective views of two embodiments of the
insulated base of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
While this invention is susceptible of embodiment in many different forms,
there is shown in the drawings and will herein be described in detail
several embodiments of the invention. It should be understood, however,
that the present disclosure is to be considered as an exemplification of
the principles of the invention and is not intended to limit the invention
to the specific embodiments illustrated.
Before describing the method to manufacture the fuse holder that is the
subject of the present invention, the fuse holder resulting from the
method will be described so as to facilitate an understanding of the
manufacturing process.
Fuse Block
Turning to FIGS. 1, 2, and 3, the fuse holder 10 that is the subject of the
present invention comprises: an insulated base 12, an electrical bus
member or terminal plate 14, a plurality of fuse terminal members 16 and
an insulated cover 18. Each terminal member 16 has at one end an
electrical terminal 20 and at its opposite end, an integral fuse terminal
22. The fuse terminal 22 on the fuse terminal member 16 is aligned and
spaced apart from a corresponding fuse terminal 24 on the terminal plate
14. In the particular embodiment illustrated in the drawings, the fuse
terminals are pressure clip terminals comprising trifurcations which are
adapted to accept the generally flat blade portions of a plug-in fuse. The
terminal plate 14, in this particular embodiment is adapted to be
connected to an electrical source 99 by means of a threaded fastener 26
and the electrical terminal 20 is a spade quick-connect terminal.
The insulated base 12 is a generally flat structure (See FIG. 3) made from
thermal plastic by injection molding so as to be suitable for mounting
thereon the terminal plate 14 and the terminal members 16. The insulated
base 12 is provided with a series of mounting apertures 30a (See FIG. 2)
which can be used to mount the base, die-stamp apertures 32, cover
securing apertures 34a and hardware mounting apertures 35a (See FIG. 8).
The base member 12 is also provided with a series of pin-like projections
37a and 39a which are aligned to corresponding securing apertures 37b in
the fuse terminal members 16 (See FIGS. 18A and 18B) and apertures 39b in
the terminal plate 14 (See FIG. 4). To facilitate alignment and to insure
that the fuse terminal members 16 are properly located, a plurality of
raised recesses 33 are provided on each side of the fuse terminal
projections 37a (see detail in FIGS. 18A and A8B).
The cover member 18 is a generally flat, five-sided structure (See FIG. 3)
which is made from thermal plastic by injection molding and which includes
a top wall 19, two side walls 21, two end walls 23, and two interior
barrier walls 25 (see FIG. 17). The top wall 19 has a plurality of fuse
accepting apertures 28. The side walls 21 have a plurality of securing
tabs 34b and recesses 36b for the electrical terminals 20, such that the
electrical terminals of the fuse terminal members 16 are exposed. The fuse
apertures 28 are aligned with the fuse terminals 22 and 24 carried by the
insulated base 12. Additional apertures may be provided for electrically
connecting one end of the terminal plate 14 at a position outside of the
cover. The inside of the cover 18 (see FIG. 17) has two barrier walls 25,
tube-like extensions 30b to be received by the base mounting apertures
30a, and tube-like extensions 37c to receive the fuse terminal projections
37a.
Method
Turning now to FIGS. 9 through 14, the method of forming the terminal plate
14 will now be described. The terminal plate 14 is die-stamped from a
generally flat blank of metal or copper alloy 15, such as a long strip of
electrical grade brass. To each side of a common trunk member 40 (see
reference line 41) are formed a plurality of generally parallel branches
42. To simplify the drawings (see FIGS. 10 through 14), branches 42 are
shown formed only on one side of the trunk number 40. However, it should
be understood that branches 42' can be formed to each side or to one side
of the trunk member 40 (See FIGS. 15A through 15F), symmetrically or
asymmetrically, relative to a base reference line. Moreover, the branches
need not be parallel or at right angles to the trunk. Each branch 42 is
separated from the others by spaced distance. Each branch has a relatively
short free end or distal end 44 and two relatively long edges 46 which
join the free end to the trunk member 40 (See FIG. 11). Formed along one
long edge 46 of each branch 42 are two fuse securing terminals 22 and 24,
each comprising trifurcations. The two fuse terminals 22 and 24 are
separated from each other by a lateral section 48 of reduced width (See
FIG. 12). Each terminal 22 and 24 is partially separated from the free end
44 and the trunk member 40 by two recesses or channels 50. The purpose of
the reduced width section 48 and the recesses 50 will become apparent from
the description which follows. At the free end 44 of the branch 42, the
electrical connecting terminal 20 is formed. In this particular
embodiment, the electrical terminals 20 at the end of each branch 42 are
of the well-known quick-connect variety. They provide a complete gripping
surface and give good engagement strength. A large contact surface also
affords the highest affordable electrical conductivity. Other electrical
terminal connecting means may be stamped into each branch, i.e., screw
connections, trifurcations, box connector, solder connectors, etc. Here
the electrical terminals 20 are formed approximately 45 degrees to the
plane of the terminal plate (See FIG. 3).
Each fuse terminal 22 and 24 is formed generally at right angles (See FIG.
13) to the plane of the terminal plate 14. The fuse terminals 22 and 24
are separated from each other by a distance generally equal to the
distance between the blade portions of the associated fuse 100. Between
the electrical terminal 20 at the free end of each branch and the adjacent
fuse terminal 22, a securing aperture 37b is formed. Finally, a plurality
of apertures 39b are formed on the trunk 40. Proper alignment of the
formed blank on the insulated base 12 is facilitated by means of
cooperating projections 37a, and 39a, and apertures 37b and 39b and by
means of the cooperating raised insulated recesses 33 (See FIGS. 18A and
18B) and metal recess 50. The apertures 37b and 39b in conjunction with
projections 37a and 39a on the insulated base 12 facilitate heat staking
of the two parts, should that become necessary.
The steps just described are conveniently accomplished using die stamping
techniques and metal punching methods much as that used in U.S. Pat. No.
3,140,364. One or more punching steps may be used. FIGS. 9 through 14 are
illustrative.
From the foregoing it will also be appreciated that the formed metal blank
may be of any length (See FIG. 4) and any number of branches may be formed
therein. Here (See FIG. 1) the finished terminal plate 14 has eight
branches on each side of a longitudinal reference line "R".
Prior to mounting the terminal plate 14 on the insulated base 12 one pair
of lateral branches 42' (See FIG. 4) may be removed. This will allow the
trunk to extend out of the cover area so as to provide a convenient point
of attachment to a source of power 99. The reduced width lateral section
50 at the proximate end of each branch facilitates easy removal.
Prior to mounting the finished blank on the insulated base 12, a threaded
fastener 26 may be mounted onto the base (See FIG. 8). Here the hex-head
35b of a bolt is inserted into a corresponding cavity 35a in the base 12.
The threaded portion 39c of the bolt is preferably selected to pass
through a corresponding aperture 39b' in the terminal plate 14. This
allows good electrical contact for all of the fuse protected loads. Of
course other means may be used to electrically connect the terminal plate
14. Moreover, the electrical connection may be made inside the protective
cover by means of a suitable aperture in one of the end walls 23.
After the terminal plate 12 is formed, it is mounted on the insulated base
12. The apertures 39b on the terminal plate 14 are received by the
projections 39a on the insulated base 12 and the slots 50 at the ends of
each branch fit within the alignment recesses 33 (See FIG. 18A). When so
mounted the die stamp apertures 32 are located below the reduced width
sections 48 between the two fuse terminals 22 and 24 of each branch 42. At
this point the finished blank may be heat staked in position.
Once the formed blank is mounted on the insulated base, a die stamping
machine is used to sever or cut each lateral branch 42 at a position 48
generally midway between the two fuse terminals 22 and 24. The process of
die stamping forms a plurality of fuse terminal members 16 and a common
bus member 14 in one step (See FIG. 14). Heretofore, the fuse terminal
members and bus member were added to the base serially. Such a process is
time consuming and requires good manual dexterity if the assembly was to
be completed without error and with good quality.
After the fuse terminal members 16 are separated from the common bus
member, the cover 18 is installed. Here the cover securing tabs 34b are
forced into the corresponding apertures 34a in the base 12. The tube-like
extensions 37c, located on the inside of the cover 18, are received by the
pins or projections 37a on the base, thereby securely holding the fuse
terminal members in place. The barrier walls 25 reduce the potential for
arcing between the fuse terminals 22 and 24. In addition, the tube-like
extensions 30b on the inside of the cover 19 fit within apertures 30a in
the base 12 (See FIG. 2 detail).
From the foregoing description, it will be observed that numerous
variations and modifications may be effected without departing from the
true spirit and scope of the novel concept of the invention. For example,
FIG. 14A shows how the terminal plate may be formed to have terminals 22'
and 24' for accepting a cylindrical type fuse. Of course, a different
cover would be used. Other fuse accepting terminals (i.e., bifurcations),
fuses and plug-in circuit elements (e.g., circuit breakers, disconnects,
jumpers, etc.) may be accommodated. As another example, FIG. 16 depicts an
embodiment wherein two formed metal blanks are located at opposite ends of
a common insulated base 12; thus, two or more power sources may be
protected from the same fuse block. In a similar fashion, FIG. 18B
illustrates an embodiment wherein the alignment recesses 33' on the
insulated cover 12 are provided with two oppositely disposed extensions
which fit within two oppositely disposed recesses 33b in fuse terminal
member 16'. It should be understood that no limitation with respect to the
specific apparatus illustrated herein is intended or should be inferred.
It is, of course, intended to cover by the appended claims all such
modifications as fall within the scope of the claims.
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