Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – Fusible element actuated
Reexamination Certificate
2001-05-08
2003-03-04
Vortman, Anatoly (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
Fusible element actuated
C337S295000, C337S290000, C337S187000, C439S843000, C439S845000
Reexamination Certificate
active
06529113
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a push-in type fuse for use in an electric circuit of an automobile or the like. More particularly, the present invention relates to improvements of a push-in type fuse having a fuse body in which a pair of female terminal portions are integrally formed at both ends of a fusible conductor portion having a fusing portion, as well as a housing for accommodating and holding the fuse body.
The present application is based on Japanese Patent Application No. 2000-146693, which is incorporated herein by reference.
2. Description of the Related Art
FIGS. 7
to
9
show related examples of a fuse which is used in an electric circuit of an automobile or the like.
A high rated fuse
1
shown in
FIGS. 7 and 8
is comprised of a fuse body
2
formed of a metallic plate, a housing
3
formed of an insulating resin for accommodating and holding the fuse body
2
through an upper opening
3
a
, and a cover
4
formed of an insulating resin for covering the upper opening
3
a
of the housing
3
.
In the fuse body
2
, a substantially strip-shaped fusible conductor portion
2
a
having a fusing portion C and a pair of terminal portions
2
b
located at both ends of the fusible conductor portion
2
a
are integrally formed by a metallic plate.
Each of the terminal portions
2
b
is a so-called twist-on terminal in which a screwing hole
2
c
is formed. As shown in
FIG. 8
, the terminal portion
2
b
is fastened and fixed by a male screw member (bolt)
10
to a screwing nut
8
, which is provided in a fuse fitting portion
7
of a fuse box, together with an LA terminal
9
a
connected to one end of an electric wire
9
of a circuit on the fuse fitting portion side, thereby allowing the terminal portion
2
b
to be set in an electrically and mechanically connected state.
FIG. 9
illustrates a fuse body
12
of the so-called push-in type fuse.
In this fuse body
12
, a substantially strip-shaped fusible conductor portion
13
having a fusing portion
13
a
and a pair of female terminal portions
15
provided at both ends of the fusible conductor portion
13
and adapted to be engaged with and connected to a pair of mating tab terminals
14
in a circuit on the fuse fitting portion side are integrally formed by a metallic plate.
Each of the female terminal portions
15
is comprised of a back plate portion
16
formed by extending an end portion of the fusible conductor portion
13
, as well as a pair of peripheral wall portions
19
a
and
19
b
which respectively extend from both side edges of the back plate
16
, are formed by being bent with their tip portions abutting against each other at a position opposing the back plate portion
16
, and form together with the back plate portion
16
an engagement space
18
into which the mating tab terminal
14
is fitted.
In the same way as with the fuse body
2
shown in
FIG. 7
, the fuse body
12
is accommodated and held in an unillustrated housing formed of an insulating resin. A terminal lance
21
which is retained in the housing is formed in the back plate portion
16
by being cut out. A pair of presser springs
23
for pressing and urging the mating tab terminals
14
inserted in the engagement spaces
18
against the respective back plate portions
16
are integrally formed at portions of the pair of peripheral wall portions
19
a
and
19
b
opposing the respective back plate portions
16
.
In a state in which the fuse body
12
is accommodated and held in the housing formed of an insulating resin, the fuse body
12
is inserted and fitted in the fuse fitting portion where the mating tab terminals
14
are provided uprightly, and as the mating tab terminals
14
are fitted in the engagement spaces
18
, the fuse body
12
is set in a state of being electrically and mechanically connected to the mating tab terminals
14
.
However, with the high rated fuse shown in
FIGS. 7 and 8
, the terminal portions
2
b
are so-called twist-on terminals, and the screwing nuts
8
and the male screw members
10
are required as separate parts.
Accordingly, there have been problems in that the cost becomes high due to an increased number of the parts, and that the operating efficiency of assembly is not good since the operation of tightening the male screw members
10
is required at the time of fitting the fuse.
In addition, with the push-in type fuse shown in
FIG. 9
, the pair of presser springs
23
for pressing and urging the mating tab terminals
14
inserted in the engagement spaces
18
against the respective back plate portions
16
are formed integrally with the fuse body
12
.
Accordingly, in a case where, in order to improve the contact pressure of the mating tab terminal
14
with respect to the back plate portion
16
by strengthening the spring characteristic of the presser spring
23
, for example, a material of a high spring characteristic is selected as the metallic plate used, or the thickness of the presser spring
23
is made large, there arise problems in that an increase in the electrical resistance between the pair of female terminal portions
15
can result, and that the formability declines.
Namely, in general, a material having a high spring characteristic has low electrical conductivity, and can therefore cause an increase in the electrical resistance of the fuse body
12
. In addition, if the thickness is too large, there is a possibility that a crack may occur in a bent portion at the time of forming the presser spring
23
in the fuse body
12
by bending, so tat the thickness cannot be made extremely large.
Accordingly, the electrical resistance of the push-in type fuse such as the one described above is large, and therefore cannot cope with a high rated fusing characteristic of 100 amperes or higher.
In addition, the electrical path from the back plate portion
16
in contact with the mating tab terminal
14
to the fusible conductor portion
13
assumes a form of detouring the surrounding portions of the terminal lance
21
due to the cutout of the terminal lance
21
which is present midway. Therefore, there has been a problem in that an increase in the current path results, leading to an increase in the circuit resistance between the pair of female terminal portions
15
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a push-in type fuse which makes it possible to improve the spring characteristic of the presser springs at the female terminal portions and make it possible to reduce the circuit resistance between the female terminal portions and to cope with a high rating, thereby overcoming the above-described drawbacks of the related art.
To achieve the above object, according a first aspect of the present invention, there is provided a fuse which comprises:
a fuse body including a fusible conductor portion having a fusing portion, and a pair of female terminal portions integrally formed with end portions of the fusible conductor portion, wherein each of the female terminal portions includes a back plate portion extended from one of the end portions of the fusible conductor portion, and a pair of peripheral wall portions extended respectively from opposite side edges of the back plate portion, the pair of peripheral wall portions being bent so as to oppose tip portions thereof to each other at a position opposing to the back plate portion, so that an engagement space into which a mating tab terminal is insertable is formed between the back plate portion and the pair of peripheral wall portions; and
a presser spring separately formed with the fuse body, the presser spring being attached to a portion of the peripheral wall portions to which the back plate portion is opposed, so that the mating tab terminal inserted in the engagement space is pressed against the back plate portion.
In accordance with the above-described construction according to the first aspect of the present invention, since the presser spring is formed separately from the fuse body, it is possible to select the material and
Endo Takayoshi
Kondo Hiroki
Nakamura Goro
Ohashi Norihiro
Satoh Takahiro
Sughrue & Mion, PLLC
Vortman Anatoly
Yazaki -Corporation
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