Ammunition and explosives – Igniting devices and systems – Electrical primer or ignitor
Reexamination Certificate
1998-12-29
2001-10-02
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Electrical primer or ignitor
C102S202500
Reexamination Certificate
active
06295930
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circuit breaker incorporated into an automobile and others.
2. Description of the Related Art
In general, in the electric circuit incorporated into an automobile, it is common to use a fuse or fusible link as a means for quickly shutting off the electric circuit when an overcurrent or a short circuit current flows in the electric circuit. Basically, these fuse and fusible link are composed in such a manner that a fusible conductor is arranged in a case and that a terminal for connection is arranged on the outside of this case. In many cases, these fuse and fusible link are put into practical use being connected with an electric connection box.
However, the above fuse and fusible link are fused for the first time when an overcurrent flows in the electric circuit and the electric circuit is shut off. Therefore, it is impossible to forcibly shut off the electric circuit at an arbitrary time. Accordingly, in case of emergency, for example, when an automobile accident has occurred, it becomes necessary to forcibly shut off an electric circuit for the purpose of safety even if no overcurrent flows in the electric circuit. Therefore, instead of the above fuse and fusible link, or in addition to the above fuse and fusible link, it is necessary to provide a circuit breaker for forcibly shutting off the electric circuit by operation conducted from the outside.
In order to provide the above circuit breaker, as disclosed in Japanese Examined Patent Publication No. 58-47809, it is possible to use a circuit breaker by which a conductor incorporated into the circuit is broken by explosive force of gunpowder. This circuit breaker is composed as follows. An output fuse, gunpowder and filament to heat the gunpowder are enclosed in a single sealed glass case, and an input terminal connected with the filament is led outside the sealed glass case in such a manner that the input terminal penetrates the sealed glass case. A surface of this sealed glass case is covered with an explosion-proof coat.
According to the above circuit breaker, when the input terminal is given an electric current or voltage, the intensity of which is not lower than a predetermined value, and the filament is heated, the gunpowder is exploded by the heat generated in the filament. Therefore, it is possible to forcibly break the conductor by the explosive force. Accordingly, in case of emergency, for example, when an automobile accident has occurred, it is possible to shut off the circuit at any time by controlling an input current or input voltage given to the input terminal.
However, according to the circuit breaker disclosed in the above patent publication, the explosive power of gunpowder is dispersed in the sealed glass case in all directions, and only one portion of the explosive power acts on the output fuse. Therefore, a considerably high intensity of explosive power is required for breaking the fuse positively. However, when the intensity of explosive power is enhanced by increasing a quantity of gunpowder, the inside of the sealed glass case is given a high intensity of explosive force. Therefore, the sealed glass case must have a strong structure so that it can withstand the high intensity of explosive power. Further the sealed glass case must be made of expensive material or it must be subjected to a special treatment for enhancing the mechanical strength. Accordingly, the manufacturing cost is inevitably increased.
On the other hand, a great task to be accomplished is the prevention of dispersion of broken pieces of the inner structure including the conductor.
Further, Japanese Unexamined Patent Publication No. 10-55742 discloses a related circuit breaker. The circuit breaker disclosed in the above patent publication is described as follows. A conductor for composing a circuit is arranged in a case, and an explosion unit for exploding gunpowder is arranged below the conductor. In the case of emergency, the explosion unit is operated, so that the conductor is exploded. Due to the foregoing, the circuit can be quickly and forcibly shut off.
In the above circuit breaker, when the case is tightly shielded up, there is a possibility that the pressure in the case is increased too high by the action of gas generated in the explosion of gunpowder, and further it becomes difficult for the temperature in the case to be lowered. For the above reasons, it is preferable to provide vent holes on the case. However, when the vent holes are provided as described above, not only gas but also flames are dispersed from the vent holes to the outside, which has a bad influence on parts arranged in the peripheral portion. According to the related arrangement, in order to prevent the flames from dispersing from the vent holes to the outside, the case must be covered with a sufficiently large cover, the mechanical strength of which is high, or alternatively the size of the case itself must be increased. Therefore, it is difficult to reduce the overall size and weight of the circuit breaker.
SUMMARY OF THE INVENTION
In view of the above circumstances, the present invention has been accomplished. It is an object of the present invention to provide a circuit breaker, which the explosive power of gunpowder is made to act on a break portion effectively, and emergency shutoff can be safely and positively conducted by a simple and compact structure of low cost; and dispersion of pieces of the inner structure caused by the explosion can be positively prevented.
To solve the above-described object, the present invention is characterized by the following features.
(1) A circuit breaker includes:
a cylindrical portion having a gunpowder and a exploding unit for exploding the gunpowder by application of electric power to the gunpowder, the cylindrical portion being provided with an opening at at least one end;
a base material securing the cylindrical portion, at least the surface of which is made of insulating material;
a conductor fixed to the base material and having a break portion located at a position opposite to the opening of the cylindrical portion, the break portion being broken by explosive force of the gunpowder;
a first metallic cover portion covering the cylindrical portion and the break portion; and
a second metallic cover portion covering the base material from an opposite side to the cylindrical portion,
wherein the first and second cover portions are fixed to the base material by directly connecting the first and second cover portions each other.
In the above structure, when the exploding unit in the cylindrical portion is operated and gunpowder is exploded, the explosive power concentrates on the break portion of the conductor which is arranged at a position close to the opening of the cylindrical portion. Due to the above structure, the break portion can be positively broken even if a small quantity of gunpowder is used. Since the break portion and the cylindrical portion are covered with the first cover portion made of metal, the mechanical strength of which is relatively high, there is no possibility that pieces of the inner structure are dispersed outside the circuit breaker.
On the assumption that the second cover portion is not provided and only the first cover portion is fixed to the base material, the following problems may be encountered. The base material to which the first cover portion is fixed is broken by the above explosive power, and the first cover portion is separated from the base material, that is, the first cover portion is disconnected from the base material. Therefore, even if the mechanical strength of the first cover itself is high, it is difficult to prevent pieces of the inner structure from dispersing. However, according to the structure of the present invention, in addition to the first cover portion, the second cover portion made of the same metal as that of the first cover portion is arranged in such a manner that the second cover portion covers the base material from an opposite side to the cylindrical portion an
Amano Junya
Hori Hiroshi
Kido Motonori
Kimura Ayumu
Kume Masahiro
Harness System Technologies Research Ltd.
Jordan Charles T.
Oliff & Berridg,e PLC
Semunegus Lulit
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