Ammunition and explosives – Igniting devices and systems – Electrical primer or ignitor
Reexamination Certificate
2002-11-21
2004-11-23
Carone, Michael J. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Electrical primer or ignitor
C102S202900, C102S202140, C280S741000
Reexamination Certificate
active
06820556
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an initiator assembly used in various kinds of gas generators such as a gas generator for an air bag, a gas generator for a seatbelt pretensioner, and a gas generator for a curtain air bag, which are safety systems of motor vehicles, and more particularly, to an initiator assembly in which an electric type initiator adapted to be actuated by an electrical signal and a metallic collar surrounding at least part of the electric type initiator are integrated with resin, a gas generator using this assembly, and a combined structure of a metallic collar and a resin in the initiator assembly.
2. Description of Related Art
An initiator assembly includes an electric type initiator adapted to be actuated by an electrical signal from a collision detecting system, and it is mounted, interposing a metallic collar or the like, to various safety devices for a motor vehicle, such as a gas generator for an air bag, a gas generator for a seatbelt pretensioner, a gas generator for a curtain air bag, and the like. Since the initiator assembly has to actuate these safety devices, reliable actuation of the initiator assembly is essential in order to actuate a gas generator unfailingly.
Also, generally in the initiator assembly, a priming included in an electric type initiator is ignited and burnt, so that it is necessary for the priming to avoid moisture absorption in order to securely actuate the initiator assembly. Furthermore, since the initiator assembly is mounted to a gas generator, it is necessary to securely seal a mounting portion of the initiator assembly to the gas generator or to seal between respective constituent elements in the initiator assembly itself in order to prevent moisture absorption of explosives as a gas generating agent charged in the gas generator. Further, the above-described operation of the initiator assembly must be not only secured, but also facilitate a manufacture of an initiator assembly itself or an assembling of the initiator assembly to a gas generator.
A conventional initiator assembly is disclosed in, for example, JP-A 11-321541. An initiating device assembly (an initiator assembly) disclosed in this publication is obtained by integrating an initiating device and a collar assembly with an injection-molded insulating material, which reduces a size of the injection-molded portion and that combines the initiating device assembly and an inflator apparatus properly and easily.
However, in the initiator assembly disclosed in this publication, nothing is considered concerning improvement of the operation reliability in the initiator assembly itself and a secure actuation in the gas generator.
Accordingly, in the conventional initiator assemblies, there is still a room to be improved in view of realizing a sufficient operation reliability and facilitating a manufacturing.
SUMMARY OF THE INVENTION
Under these circumstances, the present invention provides an initiator assembly in which a combined structure of a metallic collar and an electric type initiator is reliable to block entering of a moisture into the gas generator, and an operation reliability is secured, not increasing manufacturing steps or manufacturing cost.
The above-described problem is solved by an initiator assembly of the present invention provided with features described below.
That is, the present invention provides the initiator assembly in which an electric type initiator and a metallic collar surrounding at least part of the electric type initiator are integrated with a resin, wherein at least one of an annular protrusion and a cylindrical protrusion provided in a direction of surrounding the electric type initiator is formed on the metallic collar, and the protrusion is covered with the resin.
The electric type initiator is actuated on the basis of an actuation signal to generate a flame for actuating a gas generator, and it includes at least a single electroconductive pin, means for converting electrical energy received by the electroconductive pin to thermal energy (for example, a bridge wire), and a priming which is ignited by the converted thermal energy to be burnt. Also, the metallic collar is for fixing the electric type initiator to the gas generator and it has at least one or more protrusions.
The protrusion is formed in an annular shape and/or a cylindrical shape to surround the electric type initiator, and it is formed on the metallic collar. As this protrusion, one or plural annular projections can be provided, or one or plural cylindrical projections can be provided or both an annular protrusion and a cylindrical protrusion can be provided. For example, when the metallic collar has an inner hole which the electroconductive pin of the electric type initiator passes through, the protrusion can be provided at a portion where the inner hole is formed. Also, the protrusion can be formed at an end surface of the metallic collar in a cylindrical shape to surround a periphery of the electric type initiator. In particular, the protrusion which is formed cylindrically is desirable, because a surface area of the protrusion can be obtained largely and a contacting area with resin can be made large enough.
The protrusion is covered with a resin integrating the electric type initiator and the metallic collar, and preferably, the protrusion is held in the thickness direction by the resin. By holding the protrusion with resin, the metallic collar and the resin can be combined more securely, so that a gap to allow moisture to pass through cannot be made between the both. In order to interpose the protrusion the resin, preferably, molding-shrinkage or post-shrinkage of the resin is utilized. Accordingly, it is preferable that the resin integrating the electric type initiator and the metallic collar is injection-molded between the both members. It is also preferable that the resin is injected to cover the protrusion in the injection-molding. The resin desirably molding-shrinks or post-shrinks by the injection-molding so that the resin can hold the protrusion.
As described above, in the initiator assembly of the present invention, the protrusion is provided at the metallic collar, so that the metallic collar and the resin can be combined securely by utilizing the molding-shrinkage or the post-shrinkage of resin without causing any difficulty in manufacturing.
Incidentally, taking account of interposing the protrusion by a molding-shrinkage or a post-shrinkage of a resin, preferably, the protrusion is made thicker, but not to such an extent that a structure of the initiator assembly is disturbed. For this reason, it is preferable that the thickness of the protrusion is decided in view of a molding-shrinkage rate of resin to be used.
In the present invention, a preferable resin which integrates the electric type initiator and the metallic collar has the molding-shrinkage rate of 1% or less, more preferably between 0.1 and 0.8%. Even a resin which becomes solidified after being injection-molded can be used in the initiator assembly of the present invention because any resin molding-shrinks to some extent. However, a resin with such a large molding-shrinkage that a molding-shrinkage rate exceeds 1% is undesirable because it is deformed, warped or obtains a shrink mark after solidification, and consequently, a gap may be formed between the electrical type initiator and the resin or between the metallic collar and the resin. When the molding-shrinkage rate is not less than 0.1%, the protrusion can be held securely by the molding-shrinkage of resin, which is preferable.
Incidentally, a resin containing inorganic charging material such as glass fiber, inorganic filler or the like is known that molding-shrinkage rates in a flowing direction (MD) of injection-molded resin and in a direction (TD) perpendicular thereto are different from each other due to the orientation of the organic filling material. Therefore, in case that such a resin is used, a resin having such molding-shrinkage rates (in the flowing direction and the p
Bergin James S.
Birch & Stewart Kolasch & Birch, LLP
Carone Michael J.
Daicel Chemical Industries Ltd.
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