Fused electric plug

A fused electric plug is consisted of a unique housing assembly, two unique fuse elements and an upper cover. Two unique copper plates having three leg elements are mounted respectively in the housing assembly, and the fuse elements are put on the housing directly. The upper cover is fixed to the housing assembly by a fastener or high-frequency welding or any other appropriate manner, the two fuse elements are thus connected tightly between power source and load respectively.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a novel structure of a fused electric 
plug, and, more particularly, to a fused electric plug which is 
constituted by a unique housing assembly and two unique fuse elements as 
well as an upper cover. 
2. Description of the Prior Art 
Different structures have been designed for a fused electric plug, 
especially for the plug adapted to a decoration string set. However, 
ordinary fused plugs are of complicated structure. Mass production of them 
is difficult and causes a waste of time and labor. Therefore, the cost of 
production is rather high. Furthermore, traditional forms of copper plate 
and fuses are used in the known plugs, no significant change has occurred, 
therefore, the conventional fused plug is only a rearrangement of the 
traditional copper plates, fuses and plug body. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a novel fused electric 
plug having two unique copper plates. Each plate has a three leg element 
configuration, the plate is formed by blanking from a single copper sheet. 
The first leg element of the copper plate is extended outside the plug 
body as prongs for connection power source, the other two leg elements of 
the copper plate are U-like in structure for receiving prongs of another 
plug. 
It is another object of the present invention to provide a fused electric 
plug with two fuse elements with unique structure. Each fuse element 
includes two thin conductive filaments which are fixed and separated from 
each other by a small insulative ball between them. The two conductive 
filaments on one side of the ball are used for connection to power source, 
while, that on the other side of the ball connects to a fuse. 
It is a further object of the present invention to provide a fused electric 
plug having a unique housing assembly, the housing assembly is formed with 
two holders for accommodating the two fuse elements. After the upper cover 
is fixed to the housing by means of fasteners or high-frequency welding or 
any other appropriate manner, the fuse elements are pressed and connected 
to the copper plates and two conductive terminals respectively for current 
conducting. 
Other features and advantages of the present invention will be more 
apparent from the following description taken in connection with the 
accompanying drawing wherein:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, which is the first embodiment of the present 
invention, the fused electric plug 1 is composed of an upper cover 10, two 
fuse elements 21 and 22, and a housing assembly 30. The upper cover 10 and 
the housing body 30 are made of insulating materials such as plastics and 
the like, and, the upper cover 10 and the housing assembly 30 can be fixed 
together by means of at least two fastener means 23 and 24, or 
high-frequency welding, or any other appropriate manner. The drawing shows 
two fasteners 23, 24 as a representative manner of fixing. The fasteners 
23 and 24 can be passed through the holes 11 and 12 provided at the upper 
cover 10. As shown in FIG. 2, a plurality of cavities 13, 14 and 15 are 
formed on the bottom of the upper cover 10, the function of them will be 
discussed hereinafter. Each of the fuse elements 21 (or 22) has two thin 
conductive filaments which are fixed together by an insulative ball 27 (or 
28) between them. Thus, one side of the insulative ball 27 (or 28) has two 
conductive portions 211 and 212 (or 221 and 222), while the other side of 
the ball 27 (or 28) has the other two conductive portions 211A and 212B 
(or 221A and 222B). Obviously, the conductive portions 211, 212 (222) are 
integrally connected to the other conductive portions 211A, 212B (or 221A, 
222B). Two fuse filaments 311, 321 are jointed between the said two 
portions 221A-212B and 221A-222B on the other side of the balls 27, 28 
respectively. 
There are two slot openings 33A and 33B formed at the rear end of the body 
of the housing 30. Two copper plates 34A, 34B are mounted respectively to 
the housing 30 and in parallel direction each other. The structure of the 
copper plate is shown in FIG. 4 for details. The copper plate 34 is made 
from a single metal sheet at the proper distance from the longitudinal 
axis of the plate, it is blanked out for forming a first leg element 341 
which is projecting outside the plate body, then a second leg element 345 
and a third leg element 346 remain in the plate body. Between the second 
and third leg elements 345 and 346, there is a space 343 which is formed 
after the pressing of the first leg element 341, the end 344 is a common 
end for legs 345 and 346, of course, the legs 345, 346 may be separated 
from each other. The copper plate 34, without being pressed, is a flat 
planar portion such as portion 342. According to this structure, the 
aforementioned plates 34A and 34B have flat portions 342A and 342B 
extending outside the housing 30 as prongs respectively, while the leg 
elements 341, 345 and 346 are placed in the housing 30. Curved ends 345A 
and 344B are stopped by two cavities 35 and 36 formed in the housing 30 
respectively. The second and third legs are formed in a chuck 
configuration which aligns with the said slot openings 33A and 33B. 
Therefore, prongs of another plug can be inserted therein for serial 
connection. 
On the upper side of the housing 30, there are vertical insulating portions 
29C and 29D. Near the second leg elements 345A, 345B of the plates 34A, 
34B, there are two pairs of vertical walls 29E-29F and 29H-29J, then, 
spaces 29G and 29K are formed between each pair of vertical walls. Two 
conductive terminals 29A and 29B are placed between the second legs 345A, 
345B and the said insulating portions 29C and 29D respectively. The 
conductive terminals 29A and 29B are of traditional structure, two 
conductors 291A, 291B of two PVC wires 25, 26 are connected respectively 
by the two terminals 29A, 29B. The two terminals 29A and 29B are inserted 
into the housing 30 through a hole 30H (as shown in FIG. 3) from the 
bottom side of the housing 30. Therefore, the insulating portions 29C and 
29D are provided for insulating the terminals 29A and 29B from the second 
legs 345A and 345B of the copper plate 34A, 34B respectively. 
Two holes 31 and 32, formed with threads, are perforated through the 
housing 30 symmetrically, the locations of which are relative to the holes 
11 and 12 at the upper cover 10 for installation of fasteners 23 and 24. 
The holes 11, 12 31 and 32 can be omitted if high-frequency welding 
techniques are used for fixing the upper cover 10 to the housing assembly 
30. 
During assembly, the terminals 29A and 29B are placed near the insulating 
portions 29C and 29D respectively, the two conductive filaments 211, 212; 
221 and 222 on one side of the fuse elements 21 and 22 are contacted to 
the second legs 345A, 345B and terminals 29B, 29A respectively. Thus, the 
fuse filaments 311, 321 together with the other two conductive filaments 
211A-211B; 221A-221B on the other side of the fuse elements 21, 22 are 
housed within the spaces 29G and 29K respectively. It can be seen that the 
fuse elements 21, 22 are then connected between the power source (that is, 
plates 34A, 34B) and the load (that is, PVC wires 25, 26 connected to the 
terminals 29A, 29B) respectively. 
Once the upper cover 10 is fixed to the housing 30, the fuse elements 21 
and 22 are tightly pressed and therefore, there is a good conductivity. As 
shown in FIG. 2 and FIG. 3, the cavities 13, 14 and 15 are formed on the 
bottom of the upper cover 10 and are provided for receiving the vertical 
walls 29E, 29F and the terminal 29A on the housing 30. There are also 
other cavities provided on the bottom of the upper cover 10 for holding of 
another vertical walls 29H and 29J as well as the terminal 29B, which are 
not shown in the drawing. 
FIG. 5 shows another embodiment of the invention. Besides some slight 
alternations, it is substantially the same as the first embodiment. The 
plug 4 is composed of an upper cover 40 and a housing 50, both of them are 
made of insulative material. The upper cover has a flat planar surface and 
its other surface 40A is formed with a cavity 401. A first pair of 
extending members 402A and 402B are part of the cover body 40 and the 
extensions thereof are appropriately spaced apart. On the extending 
members 402A and 402B, there are projected members 402C and 402D with 
openings 402E and 402F. A second pair of extending members 403A and 403B 
are also formed as part of the cover 40 and the extensions are also 
appropriately spaced apart within the cavity. Two thin fuse plates 42 and 
43 are adhered on the surfaces of the members 403A and 403B, moreover, 
another vertical plate 405 is formed in one position of the cavity 401, 
the functions of these elements will be described below. The upper cover 
40 in the drawing is placed up side down for the purpose of clearly 
illustrating the plug elements. 
The housing 50 has two parallel slot openings 501A and 501B at the rear end 
thereof, and two receiving means 61 and 62 are placed in these slots. Two 
conductive plates 61A, 62A act as prongs for the housing 50. At the 
location where the plates 61A, 62A contact the housing body 50, they are 
bent in an s-like angle then extended into the housing 50 to form two 
inner portions 61B, 62B, thus the outer and inner portions 61A-61B and 
62A-62B are integral and parallel to each other, in addition, a space is 
presented between the inner plate 61B (62B) and the receiving means 61 
(62). The receiving means 61 and 62 are similar to the plates 34A and 34B 
in the first embodiment as mentioned above. In fact, it is an embodiment 
from which the flat portion 342 is deleted but the legs 341, 345, 346 and 
the end of 344 of the plate 34 as shown in FIG. 4 are retained. Therefore, 
each of the receiving means 61 (or 62) has the first leg 611 (or 621), the 
second leg 612 (or 622), and the third leg 623 (or 613, not shown). A hole 
66 is defined at the housing 50 for leading terminals 71 and 72 connected 
with conductors 73 and 74 into the housing 60. The terminals 71 and 72 are 
of conventional structure and having two openings 711, 712. Two conductors 
73, 74 are clamped by two crimping portions 713, 723 of the terminals 71, 
72, after the terminals 71, 72 are introduced into the housings 50 through 
the opening 66, the openings 711 and 721 can be inserted by two stands 626 
and 627 formed on the housings 50, and held by two pairs of insulating 
plates 624A-624B and 625A-625B formed on the both sides of the stands 626, 
627. Finally, the terminals 71, 72 are connected to the first leg 611 and 
621 of the receiving means 61 and 62 respectively. Whenever the conductors 
73 and 74, which are exposed outside the plug, are subjected to external 
force, the terminals 71 and 72 will not be loosen due to the presence of 
the stands 626, 627 and the two pairs of insulative plates 624A-624B and 
625A-625B. 
After the upper cover 40 and the housing 60 are joined together by means of 
bolts 81 and 82 which pass through holes 44, 45, and 64, 65 of the upper 
cover 40 and housing 50, one end of the fuse 43 is connected to the 
surface of plates 61B, while the other end of the fuse 43 is connected to 
the surface of the first leg 611 of the plate 61. Similarly, two ends of 
the second fuse 42 are connected, respectively, to the plate 62B and the 
first leg 621 of the plate 62, the fuses 43 and 42 are thus interposed 
between the power source and the load as a protection. The circuit is as 
follows: 
Power source.fwdarw.External plate 61A.fwdarw.Internal plate 61B.fwdarw.One 
end of the first fuse 43.fwdarw.The other end of the fuse 43.fwdarw.The 
first leg 611 of the plate 61.fwdarw.The conductive terminal 
71.fwdarw.Conductor 73.fwdarw.Load. 
Power source.fwdarw.External plate 62A.fwdarw.Internal plate 62B.fwdarw.One 
end of the second fuse 42.fwdarw.The other end of the fuse 42.fwdarw.The 
first leg 621 of the plate 62.fwdarw.The conductive terminal 
72.fwdarw.Conductor 74.fwdarw.Load. 
Simultaneously, the insulating plates 404A and 404B prevent movement of the 
plates 61B and 62B and thus, prevent from a short circuit due to the 
moving of plates 61B and 62B. Another insulating plate 405 ends at the 
center of hole 66 for separating the two wires 73 and 74 which are 
inserted into the housing in order to prevent a short circuit. 
Furthermore, the holes 402E of the projecting members 402C, 402D receive 
the two stands 626, 627, and the terminals 71, 72 are pressed tightly by 
the members 402C, 402D, so that the terminals 71, 72 are closely connected 
with the first leg 611 and 621 respectively. 
While the present invention has been described with reference to the 
particular structure shown, it is not confined to the details herein 
disclosed, and this application is constructed as may come within the 
purposes of the invention or the scope of the following claims.