Electricity: electrothermally or thermally actuated switches – Electrothermally actuated switches – Fusible element actuated
Reexamination Certificate
1999-06-29
2001-02-27
Picard, Leo P. (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Electrothermally actuated switches
Fusible element actuated
C337S401000, C337S405000, C337S407000, C337S408000, C307S010100, C180S279000, C200S061080
Reexamination Certificate
active
06194988
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fusion apparatus which in order to prevent the occurrence of a fire due to an abnormality such as that which occurs at the time of a collision accident of the vehicle, etc. cuts off by fusion a low melting point element such as a fuse installed in an electric circuit when an abnormality happens in a vehicle, and a circuit breaker including the same.
Generally, in an electric circuit for an automobile, a fuse or a fusible link is used in order to instantaneously break the circuit when an excess current or short-circuit current has occurred.
However, a fuse or fusible link is one that is intended to break the circuit after the occurrence of an excess current. Therefore, it is impossible to compulsively break the circuit with an arbitrary timing. Accordingly, in order to prevent a fire caused by a spark that occurs from part of the electric circuit from being taken on a fuel, etc. which has leaked due to a collision accident of the vehicle, or the like, it was necessary to compulsively break the electric circuit from the outside.
Also, most of the recent automobiles are arranged to have their inside operated with the use of a computer system and the electric circuit involved also is wired in a complicated way. Therefore, the probability that a spark occurs due to a breakage or short-circuits of the electric wire at the time of a collision of the vehicle is becoming high. For this reason, in order to prevent the occurrence of a fire, etc., it was necessary to break the circuit at a position near to the power source.
As a technique of compulsively breaking the electric circuit, there is a circuit breaker which breaks, utilizing the explosion force of explosives, a breakage portion installed at part of the conductor and thereby breaks the electric circuit (see Japanese Patent Application Laid-Open Publication No. H10-55742).
The circuit breaker includes a cylindrical portion having an opening portion, an explosive inside the cylindrical portion, a filament inside the cylindrical portion which causes a firing of the explosive by way of an external power source, a breakage portion which makes connection between the conductors in front of the opening portion, and a cover portion which resists broken pieces due to a breakage having taken place due to the explosion force of the explosive and which resists a rapid rise in pressure.
In this circuit breaker, by causing the flow of a current the quantity of which is larger than prescribed, the explosive is exploded, and, by the resulting explosion force, the breakage portion in front of the opening is compulsively broken. Accordingly, it is possible to arbitrarily select the timing at which to cause the flow of the current into the filament, through a control circuit, and therefore to break the electric circuit as the occasion demands.
On the other hand, as a technique related to the fusion of a fuse, there is known a fuse described in Japanese Patent Publication No. 59-48505. A perspective view of this fuse is made in
FIG. 1 and a
sectional view taken along a line II—II of the fuse illustrated in
FIG. 1
is made in FIG.
2
.
As illustrated in
FIGS. 1 and 2
, a capsule
104
in which a fuse conductor dissolving agent
105
is sealed, is disposed within a fuse vessel
101
. Due to the generation of heat from a fuse conductor
103
, the capsule
104
is heated. When this heated temperature has reached a prescribed temperature not higher than a fuse conductor fusion temperature, the capsule
104
is fused and destroyed.
As a result of this, at the time of a short-circuit accident, even if the current which flows into the fuse conductor
103
is smaller than a rated magnitude of fusion current, the fuse conductor
103
can be reliably cut off by fusion.
SUMMARY OF THE INVENTION
However, in the above-described circuit breaker, since the circuit breaker uses the explosion force of the explosive, it was necessary to use a strongly-built protection cover for protection thereof against broken pieces or rapid pressure rise at the time of the breakage. For this reason, the structure thereof was made up complicatedly.
The breakage portion needs specific materials which can be broken even by a small magnitude of explosion force and which can be cut off by fusion even at the time of an excess current. In addition, since it was necessary to apply specific processing to various connections of different kinds of materials of which the breakage portion, conductors, and connection terminals were made, the cost became considerably high.
Because of the necessity of cutting the fuse off by fusion even at the time of an excess current, at the position near to the power source (battery) and through which several tens of amperes usually flow, the breakage portion becomes necessarily large in size. In addition, the amount of explosive also increases with the result that the fuse fusion apparatus itself becomes large in size and strongly built. Therefore, the circuit breaker practically used was limited to one for use as a local circuit breaker.
In the above-described conventional fuse, it was difficult to incorporate the capsule
104
into the fuse vessel
101
and fix this capsule
104
. Also, when the fuse conductor dissolving agent
105
had reacted, there was a problem that the fuse vessel would be damaged due to the resulting thermal energy.
In view of the above, an object of the present invention is to provide a fusion apparatus which can quickly and reliably cut off a low melting point element such as a fuse and which is inexpensive and simple in structure and a circuit breaker including the same.
To attain the above object, a fusion apparatus according to the present invention is equipped with a low melting point element, a solid combustion agent, an igniting device, and an urging member. The low melting point element is installed within an electric circuit of the vehicle. The solid combustion agent is disposed in the vicinity of the low melting point element. The igniting device ignites the solid combustion agent when an abnormality happens in a vehicle. The urging member urges the solid combustion agent toward the low melting point element.
The solid combustion agent may be contacted with the low melting point element.
The igniting device may be caused to fire by receiving the power supplied from the outside when an abnormality happens in a vehicle.
The fusion apparatus may be further equipped with an outer casing which covers the solid combustion agent and the igniting device.
The urging member may be disposed between the solid combustion agent and the outer casing.
The fusion apparatus may be further equipped with an inner casing slidably supported inside the outer casing. The solid combustion agent and the igniting device may be fixed to the inner casing, and the urging member may be disposed between the inner casing and the outer casing.
The urging member may be constructed using a spring.
According to the above-described construction, when an abnormality happens in a vehicle, the solid combustion agent is combusted by being ignited by the igniting device and the resulting combustion heat softens the low melting point element. Since at this time the solid combustion agent is urged toward the low melting point element by the urging member, the low melting point element is quickly and reliably cut off by fusion. Accordingly, a fusion apparatus which is simple in structure and inexpensive is provided.
The outer casing may have a quality of heat insulation and include a surface electrically insulated.
According to the above-described construction, even when the low melting point element after fusion is contacted with the outer casing, the both are maintained in a state of their being electrically insulated from each other.
The solid combustion agent may contain metal powder and metal oxide. The metal powder contains therein at least one kind of element selected from the group consisting of B, Si, FeSi, Zr, Ti, and Al, while the metal oxide contains therein at least one kind of element selec
Noda Tsugio
Takamizawa Tomonori
Yamaguchi Noboru
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Picard Leo P.
Vortman Anatoly
Yazaki -Corporation
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