U.S. patent application number 10/132697 was filed with the patent office on 2002-11-28 for initiator assembly and gas generator using the same.
Invention is credited to Kubozuka, Satoshi, Oda, Shingo.
Application Number | 20020174792 10/132697 |
Document ID | / |
Family ID | 18980469 |
Filed Date | 2002-11-28 |
United States Patent
Application |
20020174792 |
Kind Code |
A1 |
Kubozuka, Satoshi ; et
al. |
November 28, 2002 |
Initiator assembly and gas generator using the same
Abstract
The present invention provides an initiator assembly in which
the number of constituent parts is reduced, manufacturing
facilitation of the constituent parts themselves is enhanced, the
initial performance can be maintained even if the initiator
assembly is used for a long term, and the conductive pins can
reliably be held even if the initiator assembly is exposed to a
high temperature. The initiator assembly comprises an electric type
initiator and a metal collar for holding the electric type
initiator, head portions of the conductive pins of the electric
type initiator are electrically insulated from each other but are
integral with each other, and the head portions are a disk in shape
as a whole.
Inventors: |
Kubozuka, Satoshi; (Hyogo,
JP) ; Oda, Shingo; (Hyogo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
18980469 |
Appl. No.: |
10/132697 |
Filed: |
April 26, 2002 |
Current U.S.
Class: |
102/202.12 |
Current CPC
Class: |
B60R 21/2644 20130101;
B60R 2021/26029 20130101; F42B 3/195 20130101; F42B 3/103
20130101 |
Class at
Publication: |
102/202.12 |
International
Class: |
F42B 003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2001 |
JP |
2001-132460 |
Claims
1. An initiator assembly comprising an electric type initiator and
a metal collar for holding the electric type initiator, wherein the
electric type initiator comprises a molded member made of an
insulating material, and a pair of conductive pins disposed to pass
through the molded member, a pair of the conductive pins being
disposed such that head portions of the conductive pins existing at
one axial end are exposed from the molded member and the other ends
of the conductive pins in their axial directions project from the
molded member, and the head portions being electrically insulated
from each other but integral with each other, the metal collar is
formed with an inward flange-like portion for holding the molded
member of the electric type initiator, and the head portions of the
conductive pins are integral with each other and a disk in shape as
a whole.
2. An initiator assembly according to claim 1, wherein the metal
collar has a supporting portion for preventing the integral head
portions of the conductive pins from passing through a central
opening of the flange-like portion.
3. An initiator assembly according to claim 1 or 2, wherein a
thickness of the head portions of the conductive pins which are
electrically insulated from each other but integral with each other
in a disk shape is 0.5 to 2 mm.
4. An initiator assembly according to any one of claims 1 to 3,
wherein the electric type initiator includes an eyelet having a
disk-shaped metal portion, the metal portion being connected to any
one of the conductive pins such that the metal portion can
electrically be connected to the conductive pin, and forming a head
portion of the one conductive pin.
5. An initiator assembly comprising an electric type initiator and
a metal collar for holding the electric type initiator, wherein the
electric type initiator comprises a molded member made of an
insulating material, a pair of conductive pins disposed to pass
through the molded member, and an eyelet for electrically
insulating both conductive pins from each other but integrally
forming the conductive pins, the metal collar is formed with an
inward flange-like portion for holding the molded member of the
electric type initiator, and the eyelet of the electric type
initiator includes a disk-shaped metal portion.
6. An initiator assembly according to claim 5, wherein the metal
collar includes a supporting portion for preventing the eyelet from
passing through a central opening of the flange-like portion.
7. An initiator assembly according to claim 5 or 6, wherein a
thickness of the metal portion of the eyelet is 0.5 to 2 mm.
8. An initiator assembly according to any one of claims 5 to 7,
wherein the eyelet includes at least one through hole passing
through the eyelet in its thickness direction, any one of the
conductive pins passes through the through hole, and the conductive
pin is electrically insulated from the other conductive pin by an
insulating material charged into the through hole.
9. An initiator assembly according to any one of claims 1 to 8,
wherein an inner peripheral surface of the flange-like portion is
formed with a projection projecting radially towards the inside of
the flange-like portion, and this projection is the supporting
portion.
10. An initiator assembly according to claim 9, wherein the molded
member has a portion shaped to receive the projection.
11. An initiator assembly comprising an electric type initiator and
a metal collar for holding the electric type initiator, wherein the
electric type initiator comprises a molded member made of an
insulating material, and the metal collar includes an inward
flange-like portion for holding the molded member of the electric
type initiator, an inner peripheral surface of the flange-like
portion is formed with a projection projecting radially towards the
inside of the flange-like portion, and the molded member receiving
the projection.
12. An initiator assembly according to any one of claims 9 to 11,
wherein the projection is formed such that an inner diameter of an
inner peripheral surface of the flange-like portion is reduced from
opposite end surfaces of the flange-like portion in its thickness
direction radially toward the inside of the flange-like
portion.
13. An initiator assembly according to any one of claims 1 to 12,
wherein the metal collar comprises a flange-like portion which is
formed into an inward flange-like shape, and a cylindrical portion
which is integrally connected to an outer periphery of the
flange-like portion, the inner periphery of the cylindrical portion
is not covered with an insulating material and the metal collar is
exposed.
14. An initiator assembly comprising an electric type initiator and
a metal collar for holding the electric type initiator, wherein the
electric type initiator comprises a molded member made of an
insulating material, a charge holder which is coupled to the molded
member to form a cavity, and a priming charged into the cavity
under pressure, a coupled portion between the molded member and the
charge holder in the cavity is formed with a groove which spreads
radially and outwardly, the groove being provided between the
molded member and the charge holder.
15. An initiator assembly according to claim 14, wherein the charge
holder includes a notched portion which is annularly formed by
notching the inner peripheral in one opening end is notched, the
molded member including a circular portion fitted into the notched
portion of the charge holder, and the groove is provided between a
bottom surface of the notched portion and an end surface of the
circular portion.
16. An initiator assembly according to claim 14 or 15, wherein the
electric type initiator includes an eyelet which electrically
insulates a pair of conductive pins from each other but integrally
forms the conductive pins, the eyelet is fitted into the circular
portion of the molded member, and an end surface of the eyelet is
exposed in the cavity side.
17. A gas generator comprising a housing which forms an outer
container, an initiator assembly disposed in the housing, and a gas
generating agent which is ignited and burnt upon activation of the
initiator assembly, wherein the initiator assembly is one described
in any one of claims 1 to 16.
18. An initiator assembly according to any one of claims 1 to 17,
wherein in the electric type initiator, an amount of change in a
conductive resistance between a pair of the conductive pins after
standing for 1000 hours in a state of flowing an electric current
of 50 mA to the bridge wire at the temperature of 80.degree. C.
under the humidity of 95% is within .+-.0.2 .OMEGA. before
standing.
19. An initiator assembly according to any one of claims 1 to 18,
wherein, in the electric type initiator, an ignition starting time
of the priming after standing for 1,000 hours in a state of flowing
an electric current of 50 mA to a pair of conductive pins at the
temperature of 80.degree. C. under the humidity of 95% is 2 msec or
less after ignition current for starting the activation of the
electric type initiator is applied.
20. An initiator assembly according to any one of claims 1 to 19,
wherein the insulating material forming the molded member is a
resin material, a glass material or a ceramic material.
21. An initiator assembly according to any one of claims 1 to 20,
wherein the insulating material forming the molded member is a
resin material.
22. An initiator assembly according to any one of claims 1 to 21,
wherein the molded member is made of a resin material, and a
maximum radial direction between the conductive pin of bubble
generated in a contact surface, in the molded member, between the
conductive pins and the resin is 0.10 mm or less.
23. An initiator assembly according to any one of claims 1 to 22,
wherein the molded member is made of a resin material, and bubble
generated in a contact surface, in the molded member, between the
conductive pins does not pass axially through the molded
member.
24. An initiator assembly according to any one of claims 1 to 23,
wherein a moisture-proof means is provided between the conductive
pin and the molded member.
25. An initiator assembly according to claim 24, wherein the
moisture proofing means is concave and convex surfaces formed
circumferentially on the periphery on part of the conductive pin
existing inside the molded member.
26. An initiator assembly according to any one of claims 1 to 25,
wherein the molded member includes a pair of the conductive pins,
and is formed by injection-molding a resin material.
27. An initiator assembly according to any one of claims 1 to 26,
wherein the molded member is made of a resin material, a
coefficient of water absorption of the resin material after being
submerged in water for 24 hours at 23.degree. C. is between 0.005
and 3.0%, and a tensile strength of the resin material is 100 to
250 MPa.
28. An initiator assembly according to any one of claims 1 to 27,
wherein the molded member is made of an insulating material, a
tensile strength of the insulating material is 100 MPa or higher
and a dielectric breakdown voltage of the insulating material is 10
MV/m or higher.
29. An initiator assembly according to any one of claims 1 to 28,
wherein the molded member is made of an insulating material, a
coefficient of linear expansion of the insulating material is
8.times.10.sup.-5/.degree. C. or less, the tensile strength of the
insulating material is 100 MPa or higher and a dielectric breakdown
voltage of the insulating material is 10 MV/m or higher.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to an initiator assembly
comprising an electric type initiator which is activated by an
electric signal at a time of collision, and more particularly to an
initiator assembly which is used in a gas generator for an air bag
or a gas generator for a seat belt pretensioner which are safety
system of a motor vehicle for burning and/or expanding a propellant
(e.g., a gas generating means), and the invention also relates to a
gas generator using the initiator assembly.
PRIOR ART
[0002] The air bag apparatus and the seat belt pretensioner play an
important part on the decrease in deaths and injuries caused by
collisions. The initiator assembly comprises an electrical type
initiator activated by the electric signal outputted from a
collision detecting system, the initiator assembly is fixed to
these safety devices via a metal collar and has a function of
starting the operation of these safety devices.
[0003] As an electrical initiator in conventional initiator
assemblies, it is known that the electric initiator includes a lot
of constituting elements, and most of the electric initiators have
a molded member and a cylindrical member which is combined with
each other to form a cavity. The initiator further has at least one
conductive pin which is a conductive path extending from the
outside of the molded member and the cylindrical member to the
cavity. An electric resistance member called a bridge wire is
arranged inside the cavity, and a conductive pin is connected
thereto. A compound having a very high thermal sensitivity, which
is called as a primer is arranged in the vicinity of the bridge
wire. Further, another compound called as an outputting charge (or
a priming) is stored inside the cavity in the vicinity of the
primer.
[0004] The initiator having the above structure starts operating
when the electric signal is transmitted to the conductive pin. The
bridge wire can convert an electric energy in the signal into a
thermal energy, and the thermal energy increases a temperature of a
resistance body, whereby an igniting reaction of the primer is
started. The igniting reaction of the primer causes an igniting
reaction of a priming, and an increase of the pressure and the heat
generated by these reactions break the cup to discharge a hot gas
and particles outside.
[0005] In the gas generator for the air bag, the hot gas and the
particles discharged from the initiator in this manner ignite a
solid gas generating agent to generate a gas for inflating the air
bag, and in the seat belt pretensioner, the hot gas and the
particles move a piston so as to retract a seat belt. Accordingly,
in order to securely operate the safety devices, it is important
that the initiator is securely activated.
[0006] Accordingly, in the conventional art, there has been
proposed various kinds of initiators for providing an electric
initiator with a high reliability and a low cost. For example, in
an electric initiator disclosed in JP-A No. 9-504599, for the
purpose of solving the above problems, it is attempted to improve a
reliability of the initiator by selecting the structure of the pin,
the structure of mounting the pin to the header, the structure of
mounting the header to the cup, the structure of mounting the
resistance body to the pin, the structure of the resistance body,
the outputting charge and the primer.
[0007] However, in the initiator assemblies (electrical type
initiator) which have been previously proposed, there is still room
for improvement in a view of securing a sufficient reliability in
operation and facility in manufacturing.
[0008] Further, since the conventional initiator assembly (electric
type initiator) is formed by combining a lot of parts, the steps in
a manufacturing process are necessarily increased, and thereby a
manufacturing cost is increased. Further, since many steps in a
manufacturing processes are required, a possibility such that
defective products may be produced also becomes high.
[0009] The conventional molded member in the initiator assembly is
made of a resin material, and a nylon 6 is used as the resin
material. However, in the header made of the nylon 6, a priming
(explosives) is moisture-absorbed and deteriorated due to
permeation of a moisture, and there may be a possibility such that
the initial performance of the initiator can not be obtained due to
the use for many years under some environment.
[0010] In the conventional initiator assembly, since the conductive
pin constituting the electric type initiator is held by the molded
member made of a resin material, the initiator assembly is exposed
to a high temperature, and when the resin portion is melted, there
is a possibility that the conductive pin can not be reliably
held.
DISCLOSURE OF THE INVENTION
[0011] Under such circumstances, the present invention provides an
initiator assembly capable of reducing the number of parts
constituting the initiator assembly, and capable of facilitating
the manufacture of the constituting parts themselves. Such an
initiator assembly should not increase the manufacturing cost of
the initiator assembly and operational reliability must be
secured.
[0012] The present invention also provides an initiator assembly
which can maintain the initial performance even if the initiator
assembly is used for a long term in a state in which a priming
(explosives) is not moisture-absorbed or deteriorated by permeation
of moisture.
[0013] The present invention also provides an initiator assembly
capable of reliably holding the conductive pin even if the
initiator assembly is exposed to a high temperature.
[0014] The above problems can be solved by an initiator assembly of
the present invention having the following features.
[0015] That is, the present invention provides an initiator
assembly comprising an electric type initiator and a metal collar
for holding the electric type initiator, wherein
[0016] the electric type initiator comprises a molded member made
of an insulating material, and a pair of conductive pins disposed
to pass through the molded member, a pair of the conductive pins
are disposed such that head portions of the conductive pins
existing at one axial end thereof are exposed from the molded
member and that the other axial end of the conductive pins project
from the molded member, the head portions are electrically
insulated from each other but integral with each other,
[0017] the metal collar is formed with an inward flange-like
portion for holding the molded member of the electric type
initiator, and
[0018] the head portions of the conductive pins are integral with
each other and a disk in shape as a whole.
[0019] In the electric type initiator of the initiator assembly
according to the present invention, an amount of change in a
conductive resistance between a pair of the conductive pins after
standing for 1000 hours in a state of flowing an electric current
of 50 mA to the bridge wire at the temperature of 80.degree. C.
under the humidity of 95% is within .+-.0.2 .OMEGA. before
standing, preferably within .+-.0.1 .OMEGA., and more preferably
within .+-.0.05 .OMEGA.. Further, an ignition starting time of the
priming in this case is set to be not later than 2 msec after
applying an ignition electric current for starting an activation of
the electric type initiator. The ignition electric current is
selected among 0.8A, 1.2A or the range between 0.8 and 1.2A.
[0020] In the present invention, the resin material is preferably
used as an insulating material to form the molded member, however,
a glass material or a ceramic material can also be used.
[0021] In the molded portion formed from, for example, a resin
material as the insulating material, it is desirable that bubbles
formed in the molded portion may provide the maximum distance of
0.10 mm or less between the conductive pin and the insulating
material in the radial direction. That is, the bubbles, formed on
the contacting surface of the conductive pin inside the molded
portion, may preferably have a largeness of 0.10 mm or less, more
preferably 0.05 mm or less, from the conductive pin in the radial
direction of the molded portion. Further, in the molded portion
formed from the insulating material, desirably, the bubbles
generated on the contacting surface between the molded portion and
the respective conductive pins do not go through along the axial
direction of the molded portion.
[0022] Further, in the electric type initiator of the initiator
assembly according to the present invention, a moisture-proofing
means can be provided between the conductive pin and the molded
portion. The moisture proofing means described above can be
realized by concave and convex surfaces or the like formed in the
peripheral direction on part within the molded portion of the
conductive pin.
[0023] The molded portion closing an end surface of a cavity
storing the priming holds a conductive pin for transmitting an
electric energy to the bridge wire.
[0024] The electric initiator of the initiator assembly described
above can be formed, for example, by making two conductive pins go
through the molded portion and having the end portions thereof
exposed on the end surface of the molded portion. And the end
portions of the conductive pins are connected to each other by the
bridge wire so as to be conductive, and the priming is press-loaded
to be in contact with the bridge wire.
[0025] This bridge wire can be formed using the electric resistance
body or can be provided by a printed wiring board as well as an
electric circuit substrate. Thus, the bridge wire of this
specification includes another printed circuit of electric
resistance wire, and a connection means that two or more members
can be connected to each other.
[0026] In the case that the cap member formed in a cylindrical body
with a top forming a cavity for storing the priming comprises a
cylindrical charge holder and a circular cover member closing a
front end of the charge holder, the press-loading of the priming
can be performed by mounting the charge holder to the molded
portion, press-loading the priming in the inner space thereof
(inside the cavity), connecting the cover member to an open end of
the charge holder, and closing the cavity in which the priming is
stored. Due to the conductive pin receiving an electric signal, the
bridge wire generates a heat to ignite and burn the priming, and
the flame thereof breaks the container forming the cavity storing
the priming and is discharged to the periphery.
[0027] In the electric type initiator described above, not only a
thermoplastic resin but also a thermosetting resin can be employed
as the resin material to form the molded portion closing the end
surface of the cavity storing the priming as well as holding the
conductive pin. In this case, it is desirable to use the resin
material in which a coefficient of water absorption after being
submerged for 24 hours at 23.degree. C. is between 0.005 and 1.0%
and a tensile strength is between 100 and 250 MPa. The coefficient
of water absorption (after being submerged for 24 hours at
23.degree. C.) of the resin material to form the molded portion is
more preferably between 0.01 and 0.5%, and further preferably
between 0.01 and 0.1%. Further, with respect to the tensile
strength of the resin material, it is more preferably between 160
and 250 MPa and further preferably between 170 and 230 MPa.
[0028] Further, as for the insulating material forming the molded
portion, the material in which a coefficient of linear expansion is
not more than 8.times.10.sup.-5/.degree. C., the tensile strength
is not less than 100 MPa and a dielectric breakdown voltage is not
less than 10 MV/m is preferably used. The tensile strength of the
insulating material described above is particularly desired to be
not less than 170 MPa and preferable to be not more than 250 MPa.
Accordingly, the tensile strength is preferable to be not less than
100 MPa but not more than 250 MPa, and particularly preferable to
be not less than 170 MPa but not more than 250 MPa. Further, in the
case of using the resin material as the insulating material, there
is preferably used the material in which the coefficient of water
absorption after being submerged for 24 hours at 23.degree. C. is
between 0.005 and 3.0%.
[0029] As the resin material described above, the thermoplastic
resin or the thermosetting resin is preferable, and the resin
further containing a glass fiber or another inorganic charging
material is preferable.
[0030] As the thermoplastic material, it is possible to use a
polybutylene terephthalate (PBT), a polyphenylene sulfide (PPS) or
a liquid crystal polymer (LCP) containing an inorganic charging
material such as a mineral. At a time of using the above resin, it
is preferable to contain 20 to 80 weight % of a glass fiber in the
polybutylene terephthalate (PBT), contain 20 to 80 weight % of a
glass fiber in the polyphenylene sulfide (PPS), and contain 20 to
80 weight % of a mineral in the liquid crystal polymer (LCP). In
particular, in the case of using a glass reinforced resin
containing the glass fiber, an orientation of the glass fiber is
desirably adjusted so as to be along the extending direction of the
conductive pin inserted to the molded portion. Further, a
percentage content of the inorganic charging material in each of
the resin material is more preferably between 30 and 50 weight
%.
[0031] As the thermosetting resin, an unsaturated polyester is
preferable.
[0032] The electric type initiator formed by using the resin
material as the insulating material can be easily manufactured and
also restrict the manufacturing cost in comparison with the case of
being formed with using the metal. Further, in the case of forming
the molded portion with using the resin material described above,
and thereby it is possible to avoid, as perfectly as possible, such
a circumstance that the moisture enters the molded portion and
reaches the priming and the priming absorbs the moisture to be
deteriorated. That is, if the molded portion described above is
used, the initial initiator performance can be obtained even after
being disposed for a long period of time under the environment in
the motor vehicle or the like. In particular, in the case of using
the polyphenylene sulfide (PPS) containing the charging material or
the liquid crystal polymer (LCP), an injection molding can be
performed and a high productivity and a low cost can be achieved,
which is desirable.
[0033] In the above initiator assembly, the initiator assembly
capable of reliably holding the conductive pin even if the
initiator assembly is exposed to a high temperature can be realized
by providing the metal collar with a supporting portion which
prevents the integral head portions of the conductive pins from
passing through a central opening of the flange-like portion. If a
thickness of the head portions of the conductive pins which are
integral with each other and a disk in shape is set to 0.5 to 2 mm,
it is possible to facilitate the manufacture and prevent the
conductive pin from being damaged.
[0034] In the present invention, the following initiator assembly
can be made.
[0035] That is, an initiator assembly comprising an electric type
initiator and a metal collar for holding the electric type
initiator, wherein
[0036] the electric type initiator comprises a molded member made
of insulating material, and a pair of conductive pins disposed to
pass through the molded member, a pair of the conductive pins are
disposed such that head portions of the conductive pins existing at
one axial end are exposed from the molded member and the other
axial end of the conductive pins project from the molded member,
the head portions are electrically insulated from each other but
integral with each other,
[0037] the metal collar is formed with an inward flange-like
portion for holding the molded member of the electric type
initiator, and a supporting portion for preventing the eyelet of
the integral conductive pins from passing through the central
opening of the flange-like portion, and
[0038] the head portions of the conductive pins are integral with
each other and a disk in shape as a whole, and a thickness of the
disk-shaped head portion is 0.5 to 2 mm.
[0039] In the above initiator assembly, the head portion existing
one end of either of the conductive pins is formed into a disk in
shape, the disk-shaped head portion is provided with a through hole
in its thickness direction, the other conductive pin is disposed in
the through hole, and an insulating material such as glass can be
charged between the head portions of the other conductive pin
disposed in through hole and the one conductive pin. In this case,
the head portion of the one conductive pin can be formed as a
separate member, and the separate head portion can be regarded as
an eyelet by combination with the insulating material such as
glass.
[0040] The above problem can also be solved by the following
invention.
[0041] That is, an initiator assembly comprising an electric type
initiator and a metal collar for holding the electric type
initiator, wherein
[0042] the electric type initiator comprises a molded member made
of an insulating material, a pair of conductive pins disposed to
pass through the molded member, and an eyelet for electrically
insulating the conductive pins from each other but integrally
forming the conductive pins,
[0043] the metal collar is formed with an inward flange-like
portion for holding the molded member of the electric type
initiator, and
[0044] the eyelet of the electric type initiator includes a
disk-shaped metal portion.
[0045] In this initiator assembly also, the initiator assembly
capable of reliably holding the conductive pins even if the
initiator assembly is exposed to a high temperature can be realized
by providing the metal collar with the supporting portion which
prevents the integral head portions of the conductive pins from
passing through the central opening of the flange-like portion. If
the thickness of the metal portion of the eyelet is set to 0.5 to 2
mm, it is possible to facilitate the manufacture of the initiator
assembly and the initiator assembly can be prevented from being
damaged. In this invention, when a resin material is used as the
insulating material forming the molded member, an electrically
insulative resin material is used unless another electrically
insulating means is provided between the conductive pins. That is,
when the molded member is made of an electrically insulative resin
material, it is possible to hold the conductive pins without
providing any means, but if the molded member is made of the
electrically conductive resin material, it is necessary to provide
a well known insulative means such as interposing an insulating
material so that the conductive pins, or the conductive pin and the
metal collar are not electrically connected to each other through
the molded member. Therefore, when the molded member is made of a
resin material, the electrically insulative resin material is
desirably used. As the resin material, a glass fiber, polyphenylene
sulfide (PPS) having inorganic charging material, or liquid crystal
polymer (LCP) having inorganic charging material such as mineral
can be used.
[0046] The eyelet electrically insulates a pair of the conductive
pins which function as conductor and integrally forms the
conductive pins. In order to electrically insulate a pair of the
conductive pins from each other, the current-carrying paths of the
conductive pins can be electrically insulated from each other using
an insulating material such as a glass. The combination of the
eyelet and the conductive pin electrically connects the one
conductive pin, for example, to the disk-shaped metal portion made
of conductive metal, disposes the other conductive pin in the
through hole which passes through the metal portion in its
thickness direction, charges the insulating material such as a
glass into the through hole, and can hold the other conductive pin.
With this, the one conductive pin and the other conductive pin are
integrally formed together by the eyelet, and both the conductive
pins are electrically insulated from each other by the insulating
material in the through hole. In this case, the eyelet comprises
the metal portion and the insulating material charged into the
through hole of the metal portion. The metal portion of the eyelet
can be regarded as a head portion of the one conductive pin.
[0047] A thickness of the metal portion of the eyelet (or head
portion of the conductive pin, the same is applied hereinafter) is
set to 0.5 to 2 mm, preferably 0.8 to 1.7 mm. If the thickness of
the metal portion is 2 mm or less, the metal portion can be formed
by press-molding. As a result, the metal portion and thus, the
eyelet can be manufactured more easily, and the manufacturing cost
can be reduced. By setting the thickness of the metal portion to
0.5 mm or more, even if the metal portion is formed by
press-molding, the metal portion can reliably be polished
thereafter. Further, when the thickness of the metal portion is set
to 0.5 mm or more, even if the conductive pins are insulated from
each other using a glass as the insulating material, a thickness of
the glass can be set to 0.5 mm or more also, so that sufficient
strength can be secured. That is, in the eyelet including the
glass, an interface between the glass portion and the metal portion
is the weakest portion, and if the thickness of the metal portion
is set to 0.5 mm or more, the thickness of the glass portion can
also be set to 0.5 mm or more and as a result, the eyelet can
withstand up to pressure of 250 kg/cm.sup.2. Therefore, if the
thickness of the metal portion of the eyelet is set to 0.5 mm or
more, even if the priming is burnt, for example, in a state in
which the molded portion is melted, the eyelet is prevented from
being damaged, and the damaged eyelet and the conductive pin are
prevented from falling out.
[0048] The metal collar holds the electric type initiator and fixes
the same to the gas generator and the like. The metal collar in the
initiator assembly at least includes an inward flange-like portion,
and a supporting portion which prevents the eyelet from passing
through the central opening of the flange-like portion. The metal
collar and the electric type initiator are coupled to each other by
holding the molded member of the electric type initiator by means
of the flange-like portion.
[0049] Even if the resin constituting the molded member is melted
by heat and the eyelet is moved, the supporting portion provided on
the metal collar can support the eyelet so that the eyelet does not
pass through the central opening of the flange-like portion. That
is, in the initiator assembly having such a supporting portion, the
molded member is formed using the thermoplastic resin as the
insulating material, and even if it is exposed to a high
temperature, the projection prevents the molded member and the
conductive pin fixed thereto from falling out and thus, the safety
of the initiator assembly can be enhanced.
[0050] The supporting portion can be realized by forming an inner
diameter of the central opening of the flange-like portion smaller
than an outer diameter of the eyelet. In this case, the inner
diameter of the central opening of the flange-like portion only
needs to be smaller than the outer diameter of the eyelet at least
part thereof and for example, the central opening may be formed
with a projection which projects radially and inwardly, or the
central opening may be formed into an oval shape, a rectangular
shape or various polygonal shapes. The supporting portion having
such a shape supports the eyelet by a portion of the central
opening whose inner diameter is reduced (supporting portion), and
this can prevents the eyelet from passing through the central
opening of the flange-like portion.
[0051] Thus, a projection which projects radially towards the
inside of the flange-like portion is formed on the inner peripheral
surface of the flange-like portion, and this projection may be
defined as the supporting portion. For example, projections are
continuously or discontinuously formed on the inner peripheral
surface of the flange-like portion circumferentially, and these can
be defined as the projections, or the projection can be formed by
reducing the inner diameter of the flange-like portion from its
opposite ends in its thickness direction toward radially inside of
the flange-like portion. In the latter case, the inner peripheral
surface of the flange-like portion can be projected radially and
inwardly while gradually inclining, and the entire portion can be
defined as the projection.
[0052] If the projection is provided on the inner peripheral
surface of the flange-like portion, it is possible to prevent the
molded member from falling out from the metal collar with a simple
structure. That is, when the molded member is formed by
injection-molding, the resin injected between the flange-like
portions is hardened in a shape which complementarily coincides
with the projection, and a molded member having a shape receiving
the projection can be formed by the hardening of the resin. As a
result, the molded member is supported also by the projection, and
it is possible to prevent the molded member from falling out from
the flange-like portions. Thus, if the projection is previously
formed on the inner peripheral surface of the flange-like portion
and the molded member is formed by the injection-molding, it is
possible to prevent the electric type initiator from falling out
from the metal collar and to reliably connect both the members to
each other without need of further working.
[0053] Thus, in the present invention, if the projection is formed
on the inner peripheral surface of the flange-like portion and this
is defined as the supporting portion, the initiator assembly has a
function for preventing the eyelet from passing, and a function for
supporting the molded member, which is preferable.
[0054] In relation to the above initiator assembly, an initiator
assembly capable of reducing the number of constituent parts and
facilitating the manufacturing of the constituent parts themselves
can be realized by the following structure.
[0055] That is, the present invention also provides an initiator
assembly comprising an electric type initiator and a metal collar
for holding the electric type initiator, wherein the electric type
initiator comprises a molded member made of an insulating material,
the metal collar includes an inward flange-like portion for holding
the molded member of the electric type initiator, an inner
peripheral surface of the flange-like portion is formed with a
projection projecting radially and inwardly of the flange-like
portion, and the molded member receives the projection. As the
insulating material forming the molded member, a thermosetting
resin or a thermoplastic resin can be used.
[0056] In the above initiator assembly, the effect obtained by
forming the projection on the inner peripheral surface of the
flange-like portion is as described above and thus, explanation
thereof will be omitted here.
[0057] In the initiator assembly, it is preferable to form the
inner periphery of the cylindrical portion integrally connected to
the outer periphery of the flange-like portion in the metal collar
is not covered with the insulating material and the metal collar is
exposed. With this, it is possible to prevent the connector
received by the inner periphery of the cylindrical portion from
falling out by a reaction caused when the initiator assembly is
activated.
[0058] In the initiator assembly, the molded member is fixed by the
inner peripheral surface of the flange-like portion and the molded
member is prevented from falling out by the projection. Therefore,
a lower end surface of the flange-like portion, i.e., a surface
thereof in which the connector is received without being covered
with a resin. In this regard, in the conventional initiator
assembly, a lower end surface of the flange-like portion is also
covered with a resin to prevent the molded member from falling out,
and according to the initiator assembly of the present invention,
the insulating material can be reduced, it is possible to prevent
the connector from falling out and thus, this is preferable to
reduce the manufacturing cost and secure the reliability of
operation.
[0059] By the structure of combining the molded member of the
initiator assembly and the charge holder forming the cavity which
accommodates the priming, it is possible to realize an initiator
assembly capable of reliably holding the priming while reducing the
manufacturing cost.
[0060] That is, an initiator assembly comprising an electric type
initiator and a metal collar for holding the electric type
initiator, wherein the electric type initiator comprises a molded
member made of a insulating material, a charge holder which is
coupled to the molded member to form a cavity, and a priming
charged into the cavity, a coupled portion between the molded
member and the charge holder in the cavity is formed with a groove
which spreads radially and outwardly, and the groove is provided
between the molded member and the charge holder.
[0061] The groove can be formed as a gap provided between a bottom
surface of a notched portion and the end surface of the circular
portion in such a manner that the charge holder is annularly
formed, the notched portion formed by notching an inner peripheral
surface of the charge holder in its one opening end, the circular
portion provided on the molded member is fitted into the notched
portion. That is, this gap can be defined as the groove. If the
groove is formed in this manner, it is unnecessary to form the
groove in the inner peripheral surface of the charge holder, and
thereby, it is possible to simplify the manufacturing process, and
to make it facilitate to manufacture the initiator assembly, and to
reduce the cost. Especially, if the charge holder is made of a
resin, it is easy to form the notched portion. This groove prevents
ignition failure which may be caused because the priming charged in
the cavity under pressure is away from the bridge wire. That is,
the priming is not always charged into the entire cavity under
pressure, a charging amount of the priming is adjusted because of
output or the like and a space is formed in the cavity in some
cases. In such a case, although the priming is charged under
pressure, the priming moves toward the space, contact between the
priming and the bridge wire is released, and ignition failure may
be caused. Thereupon, if the groove is formed in the range where
the priming is charged under pressure, the priming charged under
pressure enters the groove, and the priming in the cavity is
prevented from moving, and reliably ignition is secured.
[0062] As the insulating material forming the molded member in this
initiator assembly, a thermosetting resin or a thermoplastic resin
can be used, but it is preferable to use particularly the
thermoplastic resin in view of advantage of manufacture. This is
because that if the molded member and the charge holder are made of
a thermoplastic resin, both the members can be bonded to each other
by ultrasonic welding and as a result, it is possible to shorten
the time required for welding, no solvent, no heat source, and no
adhesive are required, so that there is no danger of fire or
poisoning and the initiator assembly can be manufactured with
inexpensive equipment.
[0063] The above initiator assembly can form a gas generator for an
air bag by accommodating the initiator assembly in a housing having
a gas discharging port together with a gas generating means which
is burned and/or inflated by activation of the initiator assembly
to generate a working gas. The gas generator for an air bag is
accommodated in a module case together with the air bag (bag body)
which introduces a gas generated by the gas generator to inflate,
thereby forming an air bag apparatus. In the air bag apparatus, the
gas generator is activated when an impact sensor senses the impact,
and a combustion gas is discharged from the gas discharging port of
the housing. The combustion gas flows into the air bag and with
this, the air bag ruptures the module cover and expands, and forms
a cushion between a hard structure in the vehicle and a passenger
for absorbing the impact.
[0064] According to the present invention, it is possible to reduce
the number of parts constituting the initiator assembly, and to
enhance the facilitation of the manufacture of the constituting
parts themselves without increasing the manufacturing cost of the
initiator assembly while securing the operational reliability. When
the molded member is formed with the insulating material according
to the present invention, there can be realized the initiator
assembly capable of maintaining the initial performance even if the
initiator assembly is used for a long term in as state in which the
priming (explosives) is not moisture-absorbed or deteriorated by
permeation of a moisture.
[0065] Further, according to the initiator assembly of the
invention, it is possible to have an initiator assembly capable of
reliably holding the conductive pin even if the initiator assembly
is exposed to a high temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] FIG. 1 is a vertical cross sectional view showing an
initiator assembly of the present invention.
[0067] FIG. 2 is a vertical cross sectional view showing an
initiator assembly of other embodiment.
[0068] FIG. 3 is an enlarged view of a substantial portion of the
initiator assembly shown in FIG. 2.
[0069] FIG. 4 are horizontal cross sectional views showing a shape
of a projection in other embodiment.
[0070] FIG. 5 show manufacturing steps of the initiator assembly
shown in FIG. 1.
[0071] FIG. 6 is a vertical cross sectional view showing a gas
generator for an air bag of the present invention.
[0072] FIG. 7 is a vertical cross sectional view showing other gas
generator for an air bag of the present invention.
[0073] FIG. 8 is a vertical cross sectional view showing other gas
generator for an air bag of the present invention.
EXPLANATION OF REFERENCE NUMERALS
[0074] 1, 403 molded member
[0075] 2, 402 conductive pin
[0076] 3, 407 bridge wire
[0077] 7, 406 priming
[0078] 8, 414 eyelet
[0079] 11, 421 groove
[0080] 13, 401 metal collar
[0081] 20 cup member
[0082] 22 gas generating agent
[0083] 100 initiator assembly
[0084] 103 housing
[0085] 404 base portion
[0086] 408 flange-like portion
[0087] 413 projection
[0088] 415 through hole
PREFERRED EMBODIMENTS OF THE INVENTION
[0089] A gas generator for an air bag of the present invention will
be explained below based on the embodiments shown in the
drawings.
[0090] FIG. 1 is a vertical cross sectional view showing a
preferred embodiment of the initiator assembly of the present
invention.
[0091] The initiator assembly shown in FIG. 1 comprises a metal
collar 401 having a flange-like portion 408, and an electric type
initiator held by the metal collar. The electric type initiator
comprises a molded member 403 using a resin material as an
insulating material, an eyelet 414 which is exposed at an end
portion of the molded member, and a pair of conductive pins 402
which are electrically insulated by the eyelet but integrally held
by the molded member.
[0092] Especially in the present embodiment, as a resin material
forming a molded portion, there is used a glass fiber, a
polyphenylene sulfide (PPS) including other inorganic charging
materials, or a resin material such as liquid crystal polymer (LCP)
including inorganic charging material such as a mineral. The
polyphenylene sulfide (PPS) including 40 weight % of a glass fiber
has dielectric breakdown voltage of 12 MV/m. The liquid crystal
polymer (LCP) including 50 weight % of a mineral has dielectric
breakdown voltage of 66 MV/m. The polyphenylene sulfide including
40 weight % of a glass fiber has coefficient of water absorption of
0.015% after being submerged for 24 hours at 23.degree. C. and has
a tensile strength of 196 MPa. The liquid crystal polymer including
50 weight % of mineral has coefficient of water absorption of 0.04%
after being submerged for 24 hours at 23.degree. C., and tensile
strength of 171 MPa.
[0093] When this initiator assembly is manufactured, conductive
pins 402 integrally formed by the eyelet 414 are disposed in the
flange-like portion 408 of the metal collar 401, a resin material
to be a molded member 403 is injection-molded between both the
members 408 and 402, and the metal collar 401 and the conductive
pins 402 integrally formed by the eyelet 414 are integrally formed.
In this manner, a base portion 404 of the initiator assembly is
formed by the metal collar 401, the conductive pins 402 integrally
formed by the eyelet 414 and the molded member 403.
[0094] In the initiator assembly shown in the present embodiment, a
charge holder 410 is used for disposing a priming 406, a
cylindrical cover member 405 with a top is formed at its opening
edge with a flange 409, and the flange 409 is connected to a base
portion 404 (more specifically, to a flange-like portion 408 of the
metal collar 401).
[0095] In the present embodiment, the eyelet 414 comprises a
disk-shaped metal portion 417 made of a conductive metal. The metal
portion 417 is formed with one through-hole 415 passing through the
metal portion 417 in its thickness direction. One of the conductive
pins 402a is formed integrally on the eyelet 414 in a conductive
state, and the other conductive pin 402b passes through the through
hole 415 and is held in the through hole 415 by an insulating
material (glass) 416 charged into the through hole. Both the
conductive pins 402a and 402b are electrically insulated from each
other by the insulating material (glass) 416. In this case, the
metal portion 417 of the eyelet 414 may be regarded as a head
portion of the conductive pin 402a, and both the conductive pins
402a and 402b may be integral with each other but their heads are
electrically insulated from each other. The insulating material
(glass) is provided between the head portions of the conductive
pins. The head portions of the conductive pins are formed at one
end thereof in its axial direction to which the priming is
press-charged, and the axial other end of the conductive pins
project from the molded member 403. A connector for transmitting an
operation signal is connected to the other end portion.
[0096] A thickness of the metal portion 417 of the eyelet (or the
head portion of the conductive pin, the same is applied
hereinafter) 414 is set to 0.5 to 2 mm, more preferably to 0.8 to
1.7 mm. With this, the eyelet 414 can be formed by press-molding,
and sufficient strength between the glass portion (416) and the
metal portion 417 can be secured.
[0097] An end surface of the eyelet 414 is exposed from the base
portion 404 (more specifically, from the molded member 403). The
bridge wire 407 is provided between the conductive pin 402b in the
through hole 415 and the metal portion 417. The bridge wire 407 is
made of electrically resistance body, and converts electric energy
(operation signal) received by the conductive pin 402 into thermal
energy.
[0098] The molded member 403 which is formed by injection-molding
the resin material is formed with a cylindrical portion 411 which
projects more outwardly in the axial direction than the flange-like
portion 408 of the metal collar 401. A tip end of the cylindrical
portion 411 is formed with a circular portion 412 circularly
projecting. The circular portion 412 is fitted into a substantially
cylindrical charge holder 410 made of a resin material. The
circular portion 412 and the charge holder 410 form a cavity. The
priming 406 is charged into the cavity under pressure.
[0099] When the molded member 403 and the charge holder 410 are
combined with each other, as shown in the vertical cross sectional
view of the initiator assembly shown in FIG. 2 and the cross
sectional view of a substantial portion of an essential portion in
FIG. 3, the charge holder 410 may be formed into a cylindrical
shape, an inner periphery of one end opening of the charge holder
410 may be formed with a notch portion 419 which is notched into a
stepped notch, and the circular portion 412 of the molded member
may be fitted into the notch 419. In this case, a groove 421 is
formed between the bottom surface 420 of the stepped-notch and an
end surface of the circular portion 412 along an inner peripheral
surface of the charge holder 410. If the priming 406 is charged
into the cavity formed in this manner under pressure, the priming
is also charged into the groove 421 and pressed and solidified and
is supported in the groove 421. Therefore, even if a space exists
in the cavity, it is possible to prevent the priming 406 from
falling and moving. As a result, ignition performance of the
priming 406 is enhanced. With this design, the groove 421 can
easily be provided, and this is advantageous in manufacture and
cost.
[0100] The cavity into which the priming 406 is charged under
pressure is covered with the cylindrical cover member 405 with a
top, and the cover member 405 is connected to the base portion 404.
The eyelet 414 is disposed in a circular portion 418 of the molded
member 403.
[0101] In the present embodiment, the charge holder 410 and the
molded member 403 are made of a resin and are welded to each other
by ultrasonic welding. By welding both the members 410 and 403 by
the ultrasonic welding, the melted molded member 403 (resin) does
not touch the conductive pin, and it is possible to prevent the
bridge wire 407 provided between the conductive pins 402a and 402b
from being cut. When both the members 410 and 403 are bonded to
each other by the ultrasonic welding, it is preferable to make the
charge holder 410 and the molded member 403 of a thermoplastic
resin.
[0102] In the integrally formed base portion 404, a falling-out
preventing means for preventing the molded member 403 from falling
and/or coming out is formed on the joint portion between the metal
collar 401 and the molded member 403. In the present embodiment, a
projection 413 is formed on an inner peripheral surface of the
flange-like portion 408 of the metal collar 401 as the falling-out
preventing means, a resin material is charged in correspondence
with the projection 413, and the molded member 403 for receiving
the projection 413 is formed. In the present embodiment, the
projection 413 is formed such that an inner diameter of an inner
peripheral surface of the flange-like portion 408 is narrowed
radially towards the inside of the flange-like portion from the
opposite end surfaces of the flange-like portion in its thickness
direction.
[0103] Since the resin material is formed by injection-molding at a
central opening of the flange-like portion formed as described
above, the molded member 403 is formed to be engaged
complementarily with the inner peripheral surface of the
flange-like portion 408. If the molded member receives the
projection 413 on the inner peripheral surface of the flange-like
portion, it is possible to prevent the molded member 403 from
falling out and/or coming out from the metal collar 401.
[0104] Especially in the present embodiment, a top portion of the
projection 413 formed on the inner peripheral surface of the
flange-like portion 408 of the metal collar 401 is formed closer to
the lower portion of the flange-like portion 408. With this, a
portion of the molded member 403 higher than the top portion of the
metal collar 401 (i.e., in a portion in the priming 406 side) has a
sufficient length in its axial direction, and sufficient shearing
strength in the axial direction is secured. With this, even after
the priming 406 is ignited and burnt, the molded member 403 is
reliably held by the metal collar 401. That is, in order to obtain
shearing strength at the smallest radius portion of the molded
member 403, this portion is formed at the lower portion.
[0105] Further, the projection 413 is formed into such a size that
the eyelet 414 is blocked not to pass therethrough. More
specifically, in the present embodiment, an inner diameter of the
projection 413 is set smaller than an outer diameter of the eyelet
414. As a result, even if the molded member 403 is melted by heat
and the eyelet 414 is moved, since the eyelet 414 is supported by
the projection 413, the eyelet 414 never comes out from the
initiator assembly.
[0106] When the projection is formed, the projection may be formed
to project circularly from the inner peripheral surface of the
flange-like portion, or may project into various oval shapes as
shown in FIG. 4. In this case, the conductive pins 402a and 402b
pass through the projection 413 which projects in the oval
shape.
[0107] In the initiator assembly shown in FIG. 1 also, like the
initiator assembly shown in FIG. 2, a knurl can be formed on the
conductive pins 402a and 402b in the range where the pins exist in
the molded member 403. The knurl is formed as concave and convex
surfaces, a rib or a boss formed in the peripheral direction of the
conductive pin 402, and blocks entering of the moisture between the
conductive pin 402 and the molded portion 403, thereby making the
assembly of both members secure. In other words, the insulating
material is molded corresponding to the concave and cones surfaces,
the rib or the boss by forming the concave and convex surfaces, the
rib or the boss in the range where the conductive pins 402a and
402b exist in the molded portion and charging the insulating
material between the conductive pins 402a and 402b and the metal
collar 401, and thereby, both members are joined securely. However,
the knurl can be omitted as shown in FIG. 1, in view of easiness of
the manufacturing.
[0108] As described above, the priming 406 charged in the cavity is
separated from the ambient air by the periphery thereof being
surrounded by the cover member 405 formed in the cylindrical shape
with the top. In most cases, the cover member 405 is made of a
metal material, and a thickness thereof is adjusted so as to be
broken due to a combustion of the priming 406. Accordingly, it is
preferable that the cover member 405 has a notch in a circular end
portion (a portion forming a top) in such a manner as to be easily
and securely broken. The notch described above can be formed
radially as a groove of about 0.10 to 0.25 mm in the case of making
the cover member 305 of a stainless steel (SUS305).
[0109] In the initiator assembly shown in this aspect, the flange
409 is formed in an opening bottom edge of the cover member 405 and
the flange 409 is joined to the collar member 401 (the flange-like
portion 408) constituting the base portion 404. The cover member
405 and the metal collar 401 are joined by a welding method with a
small heat gain such as a resistance welding, a laser welding in
order to clear the possibility such that the priming 406 is ignited
at a time of joining.
[0110] The initiator assembly described above can be manufactured
in accordance with a process shown in FIG. 5. That is, as shown in
(a) of FIG. 5, two conductive pins 402 are inserted from an opening
of the flange-like portion 408 of the metal collar 401, and the
resin material is charged between the opening portion of the
flange-like portion 408 and the conductive pins 402a and 402b,
whereby the base portion 404 is formed. At a time of forming the
base portion 404, the insulating material is injection-molded so
that the molded portion 403 made thereof protrudes outwardly in the
axial direction (a protrusion 411) from the flange-like portion 408
of the metal collar 401, and an end surface of the eyelet 414 is
formed to expose at end surface of the circular portion 412
circularly protruding further than the protrusion. Then, after
polishing the base portion 404, the bridge wire 407 bridges between
the metal portion 417 of the eyelet 414 which exposes the head
portion from the end surface of the molded member 403 and the
conductive pins 402 in the through-holes (in (b) of FIG. 5).
Further, the charge holder 410 is mounted onto the circular portion
418 of the molded member 403 protruding outwardly in the axial
direction from the flange-like portion 408 of the metal collar 401,
and joined by an ultrasonic welding (in (c) of FIG. 5).
[0111] Thereafter, the priming 406 is press-loaded inside a cavity
(a priming storing space) formed by the circular portion 418 and
the charge holder 410 (in (d) of FIG. 5), the outside of the charge
holder 410 is covered with the cover member 405 formed in the
cylindrical shape with the top, and the interior of the cavity
where the priming 306 is stored is closed (in (e) of FIG. 5). Since
the opening bottom edge of the cover member 405 is formed in a
shape like a flange, this portion 409 is welded to the flange-like
portion 408 of the base portion 404 (themetal collar 401) (in (f)
of FIG. 5). It is desirable that the flange-like portion 409 of the
cover member 405 and the flange-like portion 408 of the metal
collar 401 are joined according to a welding method with a small
heat gain such as a resistance welding, a laser welding.
[0112] In the initiator assembly of the present embodiment, the
metal collar 401 is integrated with the conductive pins 402 which
are integrated by the eyelet, with the resin material to form the
base portion 404, and the initiator assembly comprises such a base
portion. Therefore, the initiator assembly shown in this embodiment
can be composed of inexpensive parts and the number of the
manufacturing steps can be reduced, so that the initiator assembly
having a less production cost can be realized. Further, since the
initiator assembly can be easily assembled, it is possible to
improve the yield.
[0113] Embodiment 2
[0114] FIGS. 6 and 7 show an embodiment of a gas generator for an
air bag formed by using the initiator assembly described above.
[0115] In the gas generator, a housing is formed by combining a
diffuser shell 101 in which a gas discharge port 104 is formed and
a closure shell 102 closing the diffuser shell, and the housing 103
includes an igniting means comprising the initiator assembly 100
and a gas generating means 105 to be ignited and burnt upon
activation of the igniting means for generating a working gas to
inflate an air bag (a bag body), and a filter means 106 for
purifying and/or cooling the working gas generated by combustion of
the gas generating means 105.
[0116] In the gas generator shown in FIG. 6, an inner cylindrical
member 108 provided with a plurality of flame-transferring ports
107 on a circumferential wall is arranged in the center inside the
housing, a space 109 for storing the igniting means is formed
inside the inner cylindrical member 108, and a combustion chamber
110 for storing the gas generating means 105 is formed in the
outside thereof in the radial direction.
[0117] In the gas generator shown in FIG. 6, the igniting means
comprises the initiator assembly 100 shown in the embodiments
described above, and a transfer charge 111 to be ignited and burnt
upon activation of the initiator assembly and ejecting a flame for
igniting the gas generating means from the flame-transferring ports
107. Among these, the initiator assembly 100 is fixed to the lower
portion of the inner cylindrical member 108. A combination of the
inner cylindrical member 108 and the initiator assembly 100 can be
obtained by crimping an end portion 112 of the opening in the inner
cylindrical member 108 and fixing the collar member 113 of the
initiator assembly 100. Further, in the inner cylindrical member
108, the opening end portion 112 in the side where the initiator
assembly 100 is received is joined to the closure shell 102 by a
welding or the like.
[0118] The gas generating means 105 is stored in the combustion
chamber 110, and the filter means 106 for purifying and/or cooling
the working gas generated due to the combustion of the gas
generating means 105 is arranged outside the same. The filter means
106 is formed in a cylindrical shape by using a laminated wire mesh
or the like, and the outer circumferential surface thereof is
arranged opposite to the inner circumferential surface of the
housing 103. Desirably, a gap forming a gas-flow path is formed
between the outer circumferential surface of the filter means 106
and the inner circumferential surface of the housing 103, whereby
the entire portion of the filter means 106 can be used. The outer
circumferential surface of the filter means 106 is supported by a
punching plate 114 formed in a porous cylindrical shape, thereby
being suppressed expansion of the filter outwardly in the radial
direction.
[0119] In the gas generator described above, when the initiator
assembly 100 is activated, the transfer charge 111 arranged in the
vicinity of the assembly is ignited and burnt, and the flame
thereof is ejected into the combustion chamber 110 through the
flame-transferring ports 107 formed in the inner cylindrical member
108. Due to the flame, the gas generating means 105 in the
combustion chamber 110 is ignited and burnt to generate a working
gas. The working gas is purified and/or cooled during passing
through the filter means 106, breaks a seal tap 115 closing the gas
discharge port 104 and is discharged from the gas discharge port
104. In this case, in FIG. 6, the reference numeral 116 denotes an
under plate formed in a substantially ring shape. This under plate
116 has a function of supporting the gas generating means inside
the combustion chamber 110.
[0120] Further, the initiator assembly shown described above can be
also used in a gas generator shown in FIG. 7. The gas generator
shown in this drawing is different from the gas generator shown in
FIG. 6, and does not include an inner cylindrical member (the
reference numeral 108 in FIG. 4) in the housing. Accordingly, the
generator is particularly characterized by a structure of the
igniting means and a method of the arranging.
[0121] That is, in the gas generator shown in this drawing, the
initiator assembly 100 is directly mounted to the closure shell 102
and the gas generating means 105 is arranged in the periphery
thereof. Therefore, in the gas generator shown in this drawing, the
transfer charge (the reference numeral 111 in FIG. 6) is not used,
and when the initiator assembly 100 is activated, the flame thereof
directly ignites and burns the gas generating means 105 to generate
a working gas for inflating the air bag.
[0122] In particular, in the aspect shown in this drawing, a
central opening 121 provided with an inwardly bent circumferential
wall portion 120 is formed in the substantially center of the
closure shell forming the housing, the initiator assembly 100 is
received in the central opening 121, and an end surface of the
circumferential wall portion 120 in the central opening 121 and the
collar member 113 of the initiator assembly 100 are connected. Both
members can be connected by suitable means such as a welding to fix
the collar member of the initiator assembly. By forming a stepped
notch portion 122 in the collar member of the initiator assembly
100 and bringing it into contact with the end surface of the
circumferential wall portion in the central opening 121 as shown in
this drawing, the initiator assembly is securely fixed and a risk
such that the assembly is fallen out at a time of activation can be
cleared. In FIG. 7, the same reference numerals are attached to the
same members as those in FIG. 6, and a description thereof will be
omitted.
[0123] Further, the initiator assembly related to the above
initiator assembly can then used as a constituent part for
manufacturing a gas generator used for pretensioner for a seat
belt.
[0124] As shown in FIG. 8, this initiator assembly holds an
electric type initiator at an end portion 14 formed into a pawl
shape in a metal collar 13, and in the electric type initiator, a
pair of conductive pins 2 which are integrally formed by an eyelet
8 are disposed in a molded member 1 made of a resin material. The
conductive pins 2 can electrically discharge by a bridge wire 3. A
circular portion 9 which projects circularly is formed on the
eyelet 8 side on the molded member 1, and the circular portion 9 is
fitted into a stepped notch 10 of a charge holder 4. The circular
portion 9 and the charge holder form a cavity 5, and a priming 7 is
charged into the cavity 5 under pressure. A groove 11 is formed in
the cavity 5 in the circular portion side, and the priming is held
by the groove 11. The cavity 5 is closed by a cover member 6.
[0125] This gas generator for the pretensioner using the initiator
assembly can employ a structure shown in FIG. 8, for example.
[0126] That is, the gas generating agent 22 to be ignited and burnt
upon an activation of the initiator, more particularly by a gas, a
flame, a mist or the like generated due to combustion of the
priming is charged in a cup member 20 formed in a cylindrical shape
with a bottom and having the opening end 23 bent in a flange-like
shape. The space charged with the gas generating agent 22 is
divided, as a combustion chamber, from the outer environment by the
cup member. And, a sealant (a sealing member or a waterproof agent)
is charged within the circular groove 15 provided in the metal
collar 13, the flange-like portion 23 of the cup member 20 is
fitted and inserted into the circular groove. Further, the
circumferential wall of the circular groove 15 is crimped to join
the initiator assembly to the cup member 20. At this time, the
charge holder 4 side of the initiator assembly is press-inserted
into the cup member. Particularly in the aspect shown in FIG. 8, in
order to easily and securely connect a connector (not shown) for
transmitting the activation signal to the gas generator, the
retainer 30 is arranged. As the retainer 30, it is possible to use
a known structure having a positioning function of the connector to
be joined with the conductive pins 2 and having a connector-holding
and fixing function.
[0127] In the gas generator for the pretensioner formed in this
manner, the initiator is activated by transmitting an igniting
electric current to the conductive pin 2 and a flame, a gas, a mist
or the like is generated due to the combustion of the priming 7.
The flame or the like ignites and burns the gas generating agent 22
stored in the chamber (the combustion chamber 24) inside the cup
member 20 so as to generate a working gas. The working gas
thereafter breaks the cup member 20 to be discharged outside.
* * * * *