U.S. patent application number 13/978465 was filed with the patent office on 2013-10-24 for gas generator.
This patent application is currently assigned to Nippon Kayaku Kabushiki Kaisha. The applicant listed for this patent is Hirotaka Mukunoki, Satoshi Ohsugi, Yusuke Tanaka. Invention is credited to Hirotaka Mukunoki, Satoshi Ohsugi, Yusuke Tanaka.
Application Number | 20130276662 13/978465 |
Document ID | / |
Family ID | 46457523 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130276662 |
Kind Code |
A1 |
Ohsugi; Satoshi ; et
al. |
October 24, 2013 |
GAS GENERATOR
Abstract
A gas generator (1A) includes a housing including a lower shell
(10) and an upper shell (20), an igniter (40), a gas generating
agent (61), and a filter (70). The housing includes a bottom plate
portion (11) to which the igniter (40) is assembled and a
combustion chamber (60) accommodating the gas generating agent
(61). The filter (70) is formed from a hollow cylindrical member
and disposed in the housing so as to surround the combustion
chamber (60) in a radial direction of the housing. The bottom plate
portion (11) is provided with a positioning portion (38) formed
from a resin-molded portion secured to the bottom plate portion
(11), which is formed by adhering a fluid resin material to an
inner surface and solidifying the same, and the positioning portion
(38) abuts to an inner circumferential surface of an axial end
portion of the filter (70) located on a side of the bottom plate
portion (11).
Inventors: |
Ohsugi; Satoshi;
(Himeji-shi, JP) ; Mukunoki; Hirotaka;
(Himeji-shi, JP) ; Tanaka; Yusuke; (Himeji-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ohsugi; Satoshi
Mukunoki; Hirotaka
Tanaka; Yusuke |
Himeji-shi
Himeji-shi
Himeji-shi |
|
JP
JP
JP |
|
|
Assignee: |
Nippon Kayaku Kabushiki
Kaisha
Tokyo
JP
|
Family ID: |
46457523 |
Appl. No.: |
13/978465 |
Filed: |
January 4, 2012 |
PCT Filed: |
January 4, 2012 |
PCT NO: |
PCT/JP12/50027 |
371 Date: |
July 5, 2013 |
Current U.S.
Class: |
102/530 |
Current CPC
Class: |
B60R 21/2644 20130101;
B60R 2021/2648 20130101; B60R 2021/26011 20130101; B60R 2021/26088
20130101; C06D 5/00 20130101 |
Class at
Publication: |
102/530 |
International
Class: |
C06D 5/00 20060101
C06D005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 2011 |
JP |
2011-001941 |
Claims
1. A gas generator, comprising: a short cylindrical housing which
is constituted of a top plate portion (21) and a bottom plate
portion (11) closing axial end portions and a circumferential wall
portion (12, 22) provided with a gas discharge opening (23) and
includes therein a combustion chamber (60) accommodating a gas
generating agent (61); an igniter (40) assembled to said bottom
plate portion (11), for burning said gas generating agent (61); a
hollow cylindrical filter (70) disposed in said housing and
surrounding said combustion chamber (60) in a radial direction of
said housing, said housing at least having a lower shell (10)
including said bottom plate portion (11) and an upper shell (20)
including said top plate portion (21); and a positioning portion
(38) formed from a resin-molded portion which is formed by
attaching a fluid resin material to an inner surface of said lower
shell (10) and solidifying the fluid resin material so that at
least a part of the resin-molded portion is secured to said lower
shell (10), for positioning said filter (70) in a radial direction
by abutting to at least one of an inner circumferential surface and
an outer circumferential surface of an axial end portion of said
filter (70) located on a side of said bottom plate portion
(11).
2. The gas generator according to claim 1, wherein said positioning
portion (38) has an annular shape abutting to said filter (70)
along a circumferential direction of said filter (70).
3. The gas generator according to claim 1, wherein a plurality of
said positioning portions (38) are arranged as aligned along a
circumferential direction of said filter (70).
4. The gas generator according to claim 1, wherein said positioning
portion (38) is located on said bottom plate portion (11) in a
portion facing said combustion chamber (60) and abuts only to the
inner circumferential surface of the axial end portion of said
filter (70) located on the side of said bottom plate portion
(11).
5. A gas generator, comprising: a short cylindrical housing which
is constituted of a top plate portion (21) and a bottom plate
portion (11) closing axial end portions and a circumferential wall
portion (12, 22) provided with a gas discharge opening (23) and
includes therein a combustion chamber (60) accommodating a gas
generating agent (61); an igniter (40) assembled to said bottom
plate portion (11), for burning said gas generating agent (61); a
hollow cylindrical filter (70) disposed in said housing and
surrounding said combustion chamber (60) in a radial direction of
said housing; and a holding portion (30) provided on said bottom
plate portion (11), for holding said igniter (40), said housing at
least having a lower shell (10) including said bottom plate portion
(11) and an upper shell (20) including said top plate portion (21),
said lower shell (10) including a protruding cylindrical portion
(17) provided to protrude toward said top plate portion (21) and an
opening (15) provided at an axial end portion of said protruding
cylindrical portion (17), which is located on a side of said top
plate portion (21), said holding portion (30) including a holding
portion main body formed from a resin-molded portion which is
formed by attaching a fluid resin material to said bottom plate
portion (11) so as to at least reach a part of an outer surface of
said bottom plate portion (11) from a part of an inner surface of
said bottom plate portion (11) through said opening (15) and
solidifying the fluid resin material so that at least a part of the
resin-molded portion is secured to said bottom plate portion (11),
for holding said igniter (40), an extended portion extending
outward from said holding portion main body along the inner surface
of said bottom plate portion (11), and a positioning portion (38)
provided in said extended portion, for positioning said filter (70)
in a radial direction by abutting to at least one of an inner
circumferential surface and an outer circumferential surface of an
axial end portion of said filter (70) located on a side of said
bottom plate portion (11).
6. The gas generator according to claim 5, wherein said extended
portion is secured to said bottom plate portion (11).
7. The gas generator according to claim 5, wherein said positioning
portion (38) has an annular shape abutting to said filter (70)
along a circumferential direction of said filter (70).
8. The gas generator according to claim 5, wherein a plurality of
said positioning portions (38) are arranged as aligned along a
circumferential direction of said filter (70).
9. The gas generator according to claim 5, wherein said positioning
portion (38) is located on said bottom plate portion (11) in a
portion facing said combustion chamber (60) and abuts only to the
inner circumferential surface of the axial end portion of said
filter (70) located on the side of said bottom plate portion (11).
Description
TECHNICAL FIELD
[0001] The present invention relates to a gas generator
incorporated in a passenger protection apparatus, and more
particularly to what is called a disc type gas generator
incorporated in an air bag apparatus equipped in a steering wheel
or the like of a car.
BACKGROUND ART
[0002] From a point of view of protection of a driver and/or a
passenger in a car or the like, an air bag apparatus which is a
passenger protection apparatus has conventionally widely been used.
The air bag apparatus is equipped for the purpose of protecting a
driver and/or a passenger against shock caused at the time of
collision of a vehicle or the like, and it receives a body of a
driver or a passenger with an air bag serving as a cushion, as the
air bag is expanded and developed instantaneously at the time of
collision of the vehicle or the like. The gas generator is
equipment which is incorporated in this air bag apparatus, an
igniter therein being ignited in response to power feed through a
control unit at the time of collision of a vehicle or the like to
thereby burn a gas generating agent with flame caused by the
igniter and instantaneously generate a large amount of gas, and
thus expands and develops an air bag. It is noted that the air bag
apparatus is equipped, for example, in a steering wheel, an
instrument panel, or the like of a car.
[0003] Gas generators of various structures are available, and in
particular, what is called a disc type gas generator is available
as a gas generator suitably made use of for a driver-seat-side air
bag apparatus equipped in a steering wheel or the like. In general,
the disc type gas generator has a short cylindrical housing of
which axial end portions are closed, a gas discharge opening being
provided in a circumferential wall of the housing, and the housing
accommodating a gas generating agent, an igniter, a filter, and the
like.
[0004] In this disc type gas generator, a filter is generally
accommodated and arranged in a housing so as to surround a
combustion chamber accommodating a gas generating agent. The filter
functions as removal means for removing by catching residues (slag)
contained in a gas generated in the combustion chamber and also
functions as cooling means for lowering a temperature of the gas as
the gas passes therethrough.
[0005] Normally, the housing is often constituted of a lower shell
having a substantially cylindrical shape with bottom, which forms a
part of a circumferential wall portion and a bottom plate portion,
and an upper shell having a substantially cylindrical shape with
bottom, which forms a remaining part of the circumferential wall
portion and a top plate portion, and in that case, the filter above
is assembled to the housing by being sandwiched between these lower
shell and upper shell.
[0006] Here, an annular plate-shaped member made of metal, which is
set on the bottom plate portion of the lower shell, is made use of
for positioning of the filter in the housing. The plate-shaped
member made of metal has an abutment portion abutting to an inner
circumferential surface of the filter after assembly around its
outer periphery, and positioning of the filter in a radial
direction is made by externally inserting the filter around the
abutment portion of the plate-shaped member made of metal during
assembly of the filter.
[0007] Here, the plate-shaped member made of metal also has a
function as an effluence prevention member preventing some of gas
from flowing out through a gap between the filter and the lower
shell and discharging through a gas discharge opening without
passage through the filter during actuation of the gas generator,
and it is arranged to extend along the inner circumferential
surface of the filter defining the combustion chamber and along the
inner surface of the lower shell after assembly.
[0008] It is noted that gas generators adopting the construction
above are disclosed, for example, in Japanese Patent Laying-Open
No. 10-81190 (PTD 1), Japanese Patent Laying-Open No. 11-189126
(PTD 2), Japanese Patent Laying-Open No. 2007-290620 (PTD 3), and
the like.
CITATION LIST
Patent Document
[0009] PTD 1: Japanese Patent Laying-Open No. 10-81190 [0010] PTD
2: Japanese Patent Laying-Open No. 11-189126 [0011] PTD 3: Japanese
Patent Laying-Open No. 2007-290620
SUMMARY OF INVENTION
Technical Problem
[0012] In a case where the construction as disclosed in any of the
documents above is adopted, however, a defective condition may be
caused in a step of filling with a gas generating agent. Normally,
in the step of filling with a gas generating agent, the combustion
chamber is filled with a prescribed amount of gas generating agent
while the plate-shaped member made of metal and the filter are
assembled to the lower shell. Here, in order to fill the combustion
chamber densely with a gas generating agent formed from a molding,
the lower shell is generally vibrated.
[0013] Here, the plate-shaped member made of metal above is
fluttered by vibration and in some cases the plate-shaped member
made of metal floats, which leads to such a defective condition
that the gas generating agent is introduced in between the
plate-shaped member made of metal and the lower shell. If such a
defective condition is caused, filling with a prescribed amount of
gas generating agent fails and an operation for taking out the gas
generating agent and again performing the filling step or the like
is required, which complicates a manufacturing process.
[0014] In addition, in a case where the construction as disclosed
in any of the documents above is adopted, a plate-shaped member
made of metal described above should be arranged in the lower
shell, and then a problem of induced complication of assembly
operations due to increase in the number of parts or a problem of
increase in weight of a gas generator as a whole due to addition of
the plate-shaped member made of metal has also arisen.
[0015] Therefore, the present invention was made to solve the
problems described above, and an object thereof is to provide a gas
generator which can readily be manufactured without any defect and
achieves lighter weight.
Solution to Problem
[0016] A gas generator based on a first aspect of the present
invention includes a housing, an igniter, a filter, and a
positioning portion. The housing is formed from a short cylindrical
member which is constituted of a top plate portion and a bottom
plate portion closing axial end portions and a circumferential wall
portion provided with a gas discharge opening and includes therein
a combustion chamber accommodating a gas generating agent. The
igniter serves for burning the gas generating agent and is
assembled to the bottom plate portion. The filter is formed from a
hollow cylindrical member disposed in the housing and surrounding
the combustion chamber in a radial direction of the housing. The
housing at least has a lower shell including the bottom plate
portion and an upper shell including the top plate portion. The
positioning portion is formed from a resin-molded portion which is
formed by attaching a fluid resin material to an inner surface of
the lower shell and solidifying the fluid resin material so that at
least a part of the resin-molded portion is secured to the lower
shell, and positions the filter in a radial direction by abutting
to at least one of an inner circumferential surface and an outer
circumferential surface of an axial end portion of the filter
located on a side of the bottom plate portion.
[0017] A gas generator based on a second aspect of the present
invention includes a housing, an igniter, a filter, and a holding
portion. The housing is formed from a short cylindrical member
constituted of a top plate portion and a bottom plate portion
closing axial end portions and a circumferential wall portion
provided with a gas discharge opening and includes therein a
combustion chamber accommodating a gas generating agent. The
igniter serves for burning the gas generating agent and is
assembled to the bottom plate portion. The filter is formed from a
hollow cylindrical member disposed in the housing and surrounding
the combustion chamber in a radial direction of the housing. The
holding portion is provided on the bottom plate portion and holds
the igniter. The housing at least has a lower shell including the
bottom plate portion and an upper shell including the top plate
portion. The lower shell includes a protruding cylindrical portion
provided to protrude toward the top plate portion and an opening
provided at an axial end portion of the protruding cylindrical
portion, which is located on a side of the top plate portion. The
holding portion includes a holding portion main body formed from a
resin-molded portion which is formed by attaching a fluid resin
material to the bottom plate portion so as to at least reach a part
of an outer surface of the bottom plate portion from a part of an
inner surface of the bottom plate portion through the opening and
solidifying the fluid resin material so that at least a part of the
resin-molded portion is secured to the bottom plate portion, for
holding the igniter, an extended portion extending outward from the
holding portion main body along the inner surface of the bottom
plate portion, and a positioning portion provided in the extended
portion, for positioning the filter in a radial direction by
abutting to at least one of an inner circumferential surface and an
outer circumferential surface of an axial end portion of the filter
located on a side of the bottom plate portion.
[0018] In the gas generator based on the second aspect of the
present invention above, preferably, the extended portion is
secured to said bottom plate portion.
[0019] In the gas generator based on the first and second aspects
of the present invention above, preferably, the positioning portion
has an annular shape abutting to the filter along a circumferential
direction of the filter.
[0020] In the gas generator based on the first and second aspects
of the present invention above, a plurality of the positioning
portions may be arranged as aligned along a circumferential
direction of the filter.
[0021] In the gas generator based on the first and second aspects
of the present invention above, preferably, the positioning portion
is located on the bottom plate portion in a portion facing the
combustion chamber and abuts only to the inner circumferential
surface of the axial end portion of the filter located on the side
of the bottom plate portion.
[0022] In the gas generator based on the first and second aspects
of the present invention above, preferably, the lower shell is made
of a press-formed product formed by press-working one plate-shaped
member made of metal.
Advantageous Effects of Invention
[0023] According to the present invention, a gas generator which
can readily be manufactured without any defect and achieves lighter
weight can be obtained.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 is a schematic diagram of a gas generator in
Embodiment 1 of the present invention.
[0025] FIG. 2 is a plan view of a lower shell of the gas generator
in Embodiment 1 of the present invention.
[0026] FIG. 3 is a schematic diagram showing a manner of assembly
of a filter to the lower shell of the gas generator in Embodiment 1
of the present invention.
[0027] FIG. 4 is a plan view of a lower shell of a gas generator
according to a variation based on Embodiment 1 of the present
invention.
[0028] FIG. 5 is a schematic diagram of a gas generator in
Embodiment 2 of the present invention.
[0029] FIG. 6 is a schematic diagram of a gas generator in
Embodiment 3 of the present invention.
[0030] FIG. 7 is a schematic diagram of a gas generator in
Embodiment 4 of the present invention.
[0031] FIG. 8 is a plan view of a lower shell of the gas generator
in Embodiment 4 of the present invention.
[0032] FIG. 9 is a plan view of a lower shell of a gas generator
according to a first variation based on Embodiment 4 of the present
invention.
[0033] FIG. 10 is a plan view of a lower shell of a gas generator
according to a second variation based on Embodiment 4 of the
present invention.
[0034] FIG. 11 is a schematic diagram of a gas generator in
Embodiment 5 of the present invention.
[0035] FIG. 12 is a plan view of a lower shell of the gas generator
in Embodiment 5 of the present invention.
[0036] FIG. 13 is a schematic diagram of a gas generator in
Embodiment 6 of the present invention.
DESCRIPTION OF EMBODIMENTS
[0037] An embodiment of the present invention will be described
hereinafter in detail with reference to the drawings. An embodiment
and a variation thereof shown below represent application of the
present invention to a disc type gas generator incorporated in an
air bag apparatus equipped in a steering wheel or the like of a
car. It is noted that the same or common elements in the embodiment
and the variation thereof shown below have the same reference
characters allotted in the drawings and description thereof will
not be repeated.
Embodiment 1
[0038] FIG. 1 is a schematic diagram of a gas generator in
Embodiment 1 of the present invention. FIG. 2 is a plan view of a
lower shell of the gas generator shown in FIG. 1. A structure of a
gas generator 1A in the present embodiment will initially be
described with reference to these FIGS. 1 and 2.
[0039] As shown in FIG. 1, gas generator 1A in the present
embodiment has a short cylindrical housing having opposing axial
ends closed, and is constructed to accommodate as components in
this housing, an igniter 40, a gas generating agent 61, a filter
70, and the like.
[0040] The short cylindrical housing includes a lower shell 10 and
an upper shell 20. Lower shell 10 and upper shell 20 are each
formed in a substantially cylindrical shape with bottom, and an
outer shell portion of the housing is formed by combining and
joining the shells such that open surfaces thereof face each other.
Lower shell 10 has a bottom plate portion 11 and a circumferential
wall portion 12 and upper shell 20 has a top plate portion 21 and a
circumferential wall portion 22.
[0041] Lower shell 10 and upper shell 20 are each formed from a
member made of metal such as stainless steel, iron steel, an
aluminum alloy, and a stainless alloy. Lower shell 10 is formed
from a metal member in a shape of a piece of block with the use of
a mold or the like, through forging, drawing, press-working, or the
like, or combination thereof. Upper shell 20 is made of a
press-formed product formed by press-working one plate-shaped
member made of metal. It is noted that electron-beam welding, laser
welding, friction welding, or the like is suitably made use of for
joining lower shell 10 and upper shell 20 to each other.
[0042] An attachment portion 13 is formed in a substantially
central portion of bottom plate portion 11 of lower shell 10. This
attachment portion 13 is a site to which igniter 40 is to be
attached. Specifically, igniter 40 is attached to an accommodation
recess portion 14 provided in attachment portion 13 from an inner
side of lower shell 10 such that a terminal pin 42 of igniter 40 is
inserted through an opening 15 provided in attachment portion 13,
and a crimping portion 13a provided at a tip end of attachment
portion 13 is crimped toward igniter 40 in this state. Thus,
igniter 40 is fixed by crimping to attachment portion 13 of lower
shell 10.
[0043] It is noted that, in an outer surface of a portion of bottom
plate portion 11 where attachment portion 13 is provided, a female
connector portion 16 is formed. This female connector portion 16 is
a site for receiving a male connector (not shown) of a harness for
connecting igniter 40 and a control unit (not shown) to each other.
In this female connector portion 16, a portion of terminal pin 42
of igniter 40 closer to a lower end is arranged as being exposed. A
male connector is inserted in female connector portion 16, so that
electrical conduction between a core wire of the harness and
terminal pin 42 is established.
[0044] Igniter 40 is an ignition device for producing flame and
includes an agent loaded portion 41 in which an ignition agent is
loaded, a pair of terminal pins 42 described above, and a cover
portion 44 provided to cover a part of terminal pin 42. Agent
loaded portion 41 contains an ignition agent generating flame as it
is ignited and burns at the time of actuation and a resistor for
igniting this ignition agent. The pair of terminal pins 42 is
connected to agent loaded portion 41 for igniting the ignition
agent.
[0045] More specifically, agent loaded portion 41 includes a squib
cup 41a made of a cup-shaped member and a base portion 41b which
closes an opening end of squib cup 41a and holds the pair of
terminal pins 42 as the pins are inserted therethrough, and has
such a construction that the resistor (bridge wire) is attached to
couple tip ends of the pair of terminal pins 42 inserted in squib
cup 41a to each other and the ignition agent is loaded into squib
cup 41a so as to surround or be proximate to this resistor. It is
noted that cover portion 44 covers not only a part of terminal pin
42 described above but also base portion 41b.
[0046] Here, a Nichrome wire or the like is generally made use of
as a resistor, and ZPP (zirconium potassium perchlorate), ZWPP
(zirconium tungsten potassium perchlorate), lead tricinate, or the
like is generally made use of as the ignition agent. It is noted
that squib cup 41a and base portion 41b are generally made of metal
or plastic and cover portion 44 is generally made of plastic.
[0047] Upon sensing collision, a prescribed amount of current flows
in a resistor through terminal pin 42. As the prescribed amount of
current flows in the resistor, Joule heat is generated in the
resistor and the ignition agent starts burning. Flame at a high
temperature caused by burning causes squib cup 41a storing the
ignition agent to burst. A time period from flow of a current in
the resistor until actuation of igniter 40 is generally not longer
than 2 milliseconds in the case where a Nichrome wire is made use
of for the resistor.
[0048] A sealing member 50 is interposed between igniter 40 and
attachment portion 13. Sealing member 50 serves to hermetically
seal an enhancer chamber 47 which will be described later by
air-tightly sealing a gap created between igniter 40 and attachment
portion 13, and it is inserted in the gap in fixing by crimping
igniter 40 to attachment portion 13. A sealing member made of a
material having sufficient heat resistance and durability is
preferably made use of as sealing member 50, and for example, an O
ring or the like made of an EPDM resin representing one type of
ethylene propylene rubber is suitably made use of.
[0049] It is noted that hermeticity of enhancer chamber 47 can
further be enhanced by separately applying a liquid sealing agent
to a portion where sealing member 50 is to be interposed. Here, a
liquid sealing agent containing a resin material excellent in heat
resistance, durability, corrosion resistance, and the like after
curing is suitably selected and made use of as the liquid sealing
agent, and for example, a cyanoacrylate-based resin or a
silicone-based resin is particularly suitably made use of as the
resin material. In addition, for the resin material, other than the
resin materials described above, a phenol-based resin, an
epoxy-based resin, a melamine-based resin, a urea-based resin, a
polyester-based resin, an alkyd-based resin, a polyurethane-based
resin, a polyimide-based resin, a polyethylene-based resin, a
polypropylene-based resin, a polyvinyl chloride-based resin, a
polystyrene-based resin, a polyvinyl acetate-based resin, a
polytetrafluoroethylene-based resin, an acrylonitrile butadiene
styrene-based resin, an acrylonitrile styrene-based resin, an
acryl-based resin, a polyamide-based resin, a polyacetal-based
resin, a polycarbonate-based resin, a polyphenylene ether-based
resin, a polybutylene terephthalate-based resin, a polyethylene
terephthalate-based resin, a polyolefin-based resin, a
polyphenylene sulfide-based resin, a polysulfone-based resin, a
polyether sulfone-based resin, a polyarylate-based resin, a
polyether ether ketone-based resin, a polyamide imide-based resin,
a liquid crystal polymer, and the like can be made use of.
[0050] A cylindrical enhancer cup 46 with bottom is fixed to
attachment portion 13 of lower shell 10 so as to cover igniter 40.
Enhancer cup 46 has a top wall portion and a sidewall portion, and
contains enhancer chamber 47 accommodating an enhancer agent 48.
Enhancer cup 46 is fixed to attachment portion 13 such that
enhancer chamber 47 provided therein faces agent loaded portion 41.
More specifically, a flange portion 46a is provided to protrude
outward, at an end portion on an opening end side of enhancer cup
46 and flange portion 46a of enhancer cup 46 is crimped by a
crimping portion 13b provided in attachment portion 13, so that
enhancer cup 46 is fixed to attachment portion 13.
[0051] Enhancer cup 46 completely hermetically seals enhancer
chamber 47 provided therein while it is fixed to attachment portion
13 of lower shell 10. This enhancer cup 46 bursts or melts with
increase in pressure or with transfer of generated heat within
enhancer chamber 47 when igniter 40 is actuated and enhancer agent
48 is ignited. It is noted that aluminum, an aluminum alloy,
plastic, or the like is suitably made use of as a material for
enhancer cup 46.
[0052] Enhancer agent 48 loaded in enhancer chamber 47 produces
thermal particles as it is ignited by the flame caused by actuation
of igniter 40 and it burns. Enhancer agent 48 should be able to
reliably start burning a gas generating agent 61 which will be
described later, and generally, a composition or the like composed
of metal powders/oxidizing agent represented by B/KNO.sub.3 or the
like is employed. For enhancer agent 48, a powdery enhancer agent,
an enhancer agent formed in a prescribed shape by a binder, or the
like is made use of. A shape of the enhancer agent formed by a
binder includes, for example, various shapes such as a granule, a
column, a sheet, a sphere, a cylinder with a single hole, a
cylinder with multiple holes, a tablet, and the like.
[0053] A combustion chamber 60 accommodating gas generating agent
61 is located in a space surrounding a portion where enhancer cup
46 described above is arranged, in the space inside the housing
constituted of lower shell 10 and upper shell 20. More
specifically, enhancer cup 46 described above is arranged to
protrude into combustion chamber 60 formed in the inside of the
housing, and a space provided in a portion facing an outer surface
of a sidewall portion of this enhancer cup 46 is formed as
combustion chamber 60.
[0054] In addition, in a space radially surrounding combustion
chamber 60 accommodating this gas generating agent 61, filter 70 is
arranged along an inner circumference of the housing. Filter 70 has
a hollow cylindrical shape, and is arranged such that a central
axis thereof substantially matches with the axial direction of the
housing.
[0055] Gas generating agent 61 is an agent which is ignited by
thermal particles generated as a result of actuation of igniter 40
and produces a gas as it burns. A non-azide-based gas generating
agent is preferably employed as gas generating agent 61, and gas
generating agent 61 is formed as a molding generally containing a
fuel, an oxidizing agent, and an additive. For the fuel, for
example, a triazole derivative, a tetrazole derivative, a guanidine
derivative, an azodicarbonamide derivative, a hydrazine derivative,
or the like, or combination thereof is made use of. Specifically,
for example, nitroguanidine, guanidine nitrate, cyanoguanidine,
5-aminotetrazole, and the like are suitably made use of. In
addition, as the oxidizing agent, for example, basic nitrate such
as basic copper nitrate, perchlorate such as ammonium perchlorate
or potassium perchlorate, nitrate containing cations selected from
an alkali metal, an alkali earth metal, a transition metal, and
ammonia, or the like is made use of. As the nitrate, for example,
sodium nitrate, potassium nitrate, or the like is suitably made use
of. Moreover, as the additive, a binder, a slag formation agent, a
combustion modifier, or the like is exemplified. As the binder, for
example, metal salt of carboxymethyl cellulose, an organic binder
such as stearate, or an inorganic binder such as synthetic
hydrotalcite and Japanese acid clay can suitably be made use of. As
the slag formation agent, silicon nitride, silica, Japanese acid
clay, or the like can suitably be made use of. In addition, as the
combustion modifier, a metal oxide, ferrosilicon, activated carbon,
graphite, or the like can suitably be made use of.
[0056] A shape of a molding of gas generating agent 61 includes
various shapes such as a particulate shape including a granule, a
pellet, and a column, and a disc shape. In addition, among columnar
moldings, a molding with holes having holes in the molding (such as
a cylindrical shape with a single hole or a cylindrical shape with
multiple holes) is also made use of. These shapes are preferably
selected as appropriate depending on specifications of an air bag
apparatus in which gas generator 1A is incorporated, and for
example, a shape optimal for the specifications is preferably
selected by selecting a shape allowing change over time of a rate
of generation of a gas during burning of gas generating agent 61.
Furthermore, in addition to a shape of gas generating agent 61, a
size of a molding or an amount thereof for filling is preferably
selected as appropriate, in consideration of a linear burning
velocity, a pressure exponent, or the like of gas generating agent
61.
[0057] For example, a filter obtained by winding and sintering a
metal wire rod of stainless steel or iron steel, a filter formed by
press-working a mesh material into which metal wire rods are
knitted to thereby pack the same, a filter obtained by winding a
perforated metal plate, or the like is made use of as filter 70.
Here, as the mesh material, specifically, a wire gauze of stocking
stitch, a plain-woven wire gauze, an aggregate of crimped metal
wire rods, or the like is made use of. In addition, as the
perforated metal plate, for example, expanded metal obtained by
making staggered cuts in a metal plate and forming holes by
widening the cuts to thereby work the metal plate in a mesh, hook
metal obtained by perforating a metal plate and collapsing burrs
caused around a periphery of the hole for flattening, or the like
is made use of. In this case, a size or a shape of a hole to be
formed can be changed as appropriate as required, and holes
different in size or shape may be included in the same metal plate.
It is noted that, for example, a steel plate (mild steel) or a
stainless steel plate can suitably be made use of as a metal plate,
and a nonferrous metal plate of aluminum, copper, titanium, nickel,
or an alloy thereof, or the like can also be made use of.
[0058] Filter 70 functions as cooling means for cooling a gas by
depriving heat at a high temperature of the gas when the gas
produced in combustion chamber 60 passes through this filter 70 and
also functions as removal means for removing by catching, slag
(residues) contained in the gas. Therefore, in order to
sufficiently cool the gas and to avoid emission of the slag to the
outside, the gas produced in combustion chamber 60 should be caused
to reliably pass through filter 70.
[0059] An outer circumferential surface of filter 70 is located at
a prescribed distance from the inner circumferential surface of
circumferential wall portion 12 of lower shell 10 and the inner
circumferential surface of circumferential wall portion 22 of upper
shell 20. A plurality of gas discharge openings 23 are provided in
circumferential wall portion 22 of upper shell 20 in a portion
facing filter 70. This gas discharge opening 23 serves to guide an
actuation gas which has passed through filter 70 to the outside of
the housing. To a main surface of circumferential wall portion 22
of upper shell 20, which is located on a side of filter 70, a
sealing member 24 is attached to close gas discharge opening 23. An
aluminum foil or the like having an adhesive member applied to its
one surface is made use of as this sealing member 24. Thus,
hermeticity of combustion chamber 60 is ensured.
[0060] In the space inside the housing, a supporting member 62 for
fixing an axial end portion of filter 70 located on the side of top
plate portion 21 to the housing is arranged at the end portion of
upper shell 20 on the side of top plate portion 21. Supporting
member 62 has a site abutting to top plate portion 21 of upper
shell 20 and a site abutting to an inner circumferential surface of
the axial end portion of filter 70 located on the side of top plate
portion 21.
[0061] In the inside of this supporting member 62, a cushion
material 64 is arranged to be in contact with gas generating agent
61 accommodated in combustion chamber 60. This cushion material 64
is provided for the purpose of preventing gas generating agent 61
made of a molding from being crushed by vibration or the like, and
a molding of ceramics fibers or a foamed resin (such as foamed
silicone) is suitably made use of.
[0062] On the other hand, as shown in FIGS. 1 and 2, in the space
inside the housing, a positioning portion 38 is located at the end
portion of lower shell 10 on the side of bottom plate portion 11.
Positioning portion 38 is provided in a portion of bottom plate
portion 11 of lower shell 10, which faces combustion chamber 60,
and has an abutment portion 38a abutting to the inner
circumferential surface of the axial end portion of filter 70
located on the side of bottom plate portion 11 and a margin for
securing 38b secured along an inner surface of bottom plate portion
11. Positioning portion 38 has an annular shape so as to abut to
filter 70 along a circumferential direction of filter 70.
[0063] Here, positioning portion 38 is a site for positioning of
filter 70 in a radial direction during assembly of filter 70 to
lower shell 10, and is formed from a resin-molded portion formed by
attaching a fluid resin material to an inner surface of bottom
plate portion 11 of lower shell 10 and solidifying the fluid resin
material. Namely, positioning portion 38 is formed by injection
molding with the use of a mold (more particularly, outsert
molding).
[0064] For a source material for positioning portion 38 formed by
injection molding, a resin material excellent in heat resistance,
durability, corrosion resistance, and the like after curing is
suitably selected and made use of. In that case, without being
limited to a thermosetting resin represented by an epoxy resin and
the like, a thermoplastic resin represented by a polybutylene
terephthalate resin, a polyethylene terephthalate resin, a
polyamide resin (such as nylon 6 or nylon 66), a polypropylene
sulfide resin, a polypropylene oxide resin, and the like can also
be made use of.
[0065] An operation of gas generator 1A in the present embodiment
will now be described with reference to FIG. 1.
[0066] When a vehicle on which gas generator 1A in the present
embodiment is mounted collides, collision sensing means separately
provided in the vehicle senses collision, and based thereon,
igniter 40 is actuated in response to power feed through a control
unit separately provided in the vehicle. Enhancer agent 48
accommodated in enhancer chamber 47 burns as it is ignited by flame
produced as a result of actuation of igniter 40 and produces a
large number of thermal particles. As this enhancer agent 48 burns,
enhancer cup 46 bursts or melts and thermal particles described
above flow into combustion chamber 60.
[0067] Thermal particles which have flowed in ignite and burn gas
generating agent 61 accommodated in combustion chamber 60 and a
large amount of gas is produced. The gas produced in combustion
chamber 60 passes through filter 70. At that time, heat is deprived
of the gas through filter 70 and the gas is cooled, slag contained
in the gas is removed by filter 70, and the gas flows into an outer
peripheral portion of the housing.
[0068] As an internal pressure in the housing increases, sealing by
sealing member 24 which has closed gas discharge opening 23 of
upper shell 20 is broken, and the gas is discharged to the outside
of the housing through gas discharge opening 23. The discharged gas
is introduced in the air bag provided adjacent to gas generator 1A
and it expands and develops the air bag.
[0069] FIG. 3 is a schematic diagram showing a manner of assembly
of the filter to the lower shell of the gas generator in the
present embodiment. A procedure for assembly of filter 70 of gas
generator 1A in the present embodiment will now be described with
reference to this FIG. 3.
[0070] As shown in FIG. 3, in gas generator 1A in the present
embodiment, since positioning portion 38 formed from the
resin-molded portion in advance by injection molding is provided on
bottom plate portion 11 of lower shell 10, assembly of filter 70
can be achieved by externally inserting hollow cylindrical filter
70 around positioning portion 38 from the inside of lower shell 10.
Here, filter 70 abuts to abutment portion 38a having an annular
shape and the inner circumferential surface of the axial end
portion of filter 70 located on the side of bottom plate portion 11
comes in contact with abutment portion 38a. Thus, filter 70 is
assembled to lower shell 10.
[0071] The following effect can be obtained by gas generator 1A in
the present embodiment described above.
[0072] Firstly, since positioning portion 38 is formed by injection
molding while it is secured to lower shell 10, positioning portion
38 does not flutter nor float by vibration even though vibration is
provided to lower shell 10 in the step of filling with gas
generating agent 61 performed after assembly of filter 70 to lower
shell 10. Therefore, such a defective condition as gas generating
agent 61 coming around an unintended portion is not caused, and
combustion chamber 60 can smoothly be filled with gas generating
agent 61 formed from a prescribed amount of molding. Therefore, by
adopting the construction above, a gas generator can readily be
manufactured without any defect.
[0073] Secondly, since positioning portion 38 is formed from the
resin-molded portion formed by injection molding, it is lighter in
weight than the conventionally employed plate-shaped member made of
metal and weight of the gas generator as a whole does not increase
more than necessary. Therefore, by adopting the construction above,
a gas generator achieving lighter weight can be obtained.
[0074] Thirdly, since positioning portion 38 has an annular shape
covering the entire inner circumferential surface of the axial end
portion of filter 70 located on the side of bottom plate portion
11, positioning portion 38 also functions as an effluence
prevention member preventing some of gas from flowing out through a
gap between filter 70 and lower shell 10 and discharging through
gas discharge opening 23 without passage through filter 70 during
actuation of gas generator 1A. Therefore, a high-performance gas
generator capable of obtaining desired gas output can be obtained
and a gas generator comparable in terms of performance to a
conventional gas generator including a plate-shaped member made of
metal as the effluence prevention member can be obtained.
[0075] Fourthly, since positioning portion 38 is formed integrally
with a holding portion 30, the assembly step is simplified.
Consequently, manufacturing cost can be reduced as compared with
the conventional example and a gas generator can inexpensively be
manufactured.
[0076] Thus, with gas generator 1A in the present embodiment, a
high-performance gas generator which can readily be manufactured
without any defect and achieves lighter weight can be obtained.
[0077] It is noted that, with gas generator 1A in the present
embodiment, as compared with a case where a plate-shaped member
made of metal is arranged in a combustion chamber as in the
conventional gas generator, a volume in combustion chamber 60
occupied by positioning portion 38 can also be decreased, so that
an effect that an amount of filling with gas generating agent 61
can accordingly be increased or a gas generator can accordingly be
reduced in size can also be obtained.
[0078] In addition, in gas generator 1A in the present embodiment,
positioning portion 38 is formed of resin. Therefore, slag caused
by combustion of gas generating agent 61 is blown toward
positioning portion 38 and adheres thereto, and thus the slag can
be entangled for removal. As compared with the case where a
plate-shaped member made of metal is arranged in a combustion
chamber as in the conventional gas generator, capability of
catching slag can be enhanced.
[0079] FIG. 4 is a plan view of a lower shell of a gas generator
according to a variation based on the present embodiment. The gas
generator according to the variation based on the present
embodiment will now be described with reference to this FIG. 4.
[0080] In gas generator 1A in the present embodiment described
above, a positioning portion having an annular shape is employed as
positioning portion 38. In the gas generator according to the
present variation, however, positioning portions arranged as
aligned intermittently along a circumferential direction of filter
70 are employed as positioning portion 38 as shown in FIG. 4. The
plurality of positioning portions 38 each have abutment portion 38a
abutting to filter 70 and margin for securing 38b, and as in the
case of the present embodiment described above, they are formed
from the resin-molded portion formed by adhering a fluid resin
material to the inner surface of bottom plate portion 11 of lower
shell 10 and solidifying the same.
[0081] In the case of such a construction as well, an effect the
same as in the case of gas generator 1A in the present embodiment
described above can be obtained. The present variation, however, is
constructed such that the inner circumferential surface of the
axial end portion of filter 70 located on the side of bottom plate
portion 11 is partly not covered with positioning portion 38, and
therefore positioning portion 38 does not exhibit the function as
the effluence prevention member described above. In a case where
gas discharge opening 23 is provided at a position relatively
closer to an upper end portion of circumferential wall portion 12,
22 of the housing, a case where mechanical strength of lower shell
10 is sufficiently high, or the like, however, there may also
originally be no possibility that the gas flows out from between
filter 70 and lower shell 10, and in that case, an amount of resin
material used for forming positioning portion 38 can be reduced by
adopting the construction as in the present variation and a gas
generator of lighter weight can be manufactured more
inexpensively.
Embodiment 2
[0082] FIG. 5 is a schematic diagram of a gas generator in
Embodiment 2 of the present invention. A gas generator 1B in the
present embodiment will be described below with reference to this
FIG. 5.
[0083] As shown in FIG. 5, in gas generator 1B in the present
embodiment, positioning portion 38 is not provided on bottom plate
portion 11 of lower shell 10, but is provided on a curved corner
portion 19 located between bottom plate portion 11 and
circumferential wall portion 12. Positioning portion 38 has
abutment portion 38a abutting to the outer circumferential surface
of the axial end portion of filter 70 located on the side of bottom
plate portion 11 and margin for securing 38b secured along an inner
surface of curved corner portion 19. As in the case of Embodiment 1
of the present invention described above, positioning portion 38 is
formed from the resin-molded portion formed by adhering a fluid
resin material to the inner surface of lower shell 10 and
solidifying the same. It is noted that assembly of filter 70 to
lower shell 10 is carried out by internally inserting hollow
cylindrical filter 70 around positioning portion 38 from the inside
of lower shell 10.
[0084] In the case of gas generator 1B in the present embodiment
described above as well, an effect the same as in the case of gas
generator 1A in Embodiment 1 of the present invention described
above can be obtained. Namely, since positioning portion 38 is
formed by injection molding while it is secured to lower shell 10,
a gas generator which can readily be manufactured without any
defect and achieves lighter weight can be obtained. In addition, in
the case where positioning portion 38 is formed to have an annular
shape as in the case of Embodiment 1 of the present invention
described above, positioning portion 38 also exhibits the function
as the effluence prevention member. In the case where a plurality
of positioning portions 38 are arranged as aligned intermittently
along the circumferential direction of filter 70, further lighter
weight and lower cost can be achieved.
Embodiment 3
[0085] FIG. 6 is a schematic diagram of a gas generator in
Embodiment 3 of the present invention. A gas generator 1C in the
present embodiment will be described below with reference to this
FIG. 6.
[0086] As shown in FIG. 6, in gas generator 1C in the present
embodiment, positioning portion 38 is provided to lie astride
bottom plate portion 11 of lower shell 10 and curved corner portion
19. Positioning portion 38 has an abutment portion 38a1 abutting to
the inner circumferential surface of the axial end portion of
filter 70 located on the side of bottom plate portion 11, an
abutment portion 38a2 abutting to the outer circumferential surface
of the axial end portion of filter 70 located on the side of bottom
plate portion 11, and margin for securing 38b continuing to these
abutment portions 38a1, 38a2 and secured to the inner surface of
bottom plate portion 11 of lower shell 10 and the inner surface of
curved corner portion 19. In addition, an end surface of the axial
end portion of filter 70 located on the side of bottom plate
portion 11 abuts to margin for securing 38b. As in the case of
Embodiment 1 of the present invention described above, positioning
portion 38 is formed from the resin-molded portion formed by
adhering a fluid resin material to the inner surface of lower shell
10 and solidifying the same. It is noted that assembly of filter 70
to lower shell 10 is carried out by inserting hollow cylindrical
filter 70 in between abutment portions 38a1, 38a2 provided in
positioning portion 38 from the inside of lower shell 10.
[0087] In the case of gas generator 1C in the present embodiment
described above as well, an effect the same as in the case of gas
generator 1A in Embodiment 1 of the present invention described
above can be obtained. Namely, since positioning portion 38 is
formed by injection molding while it is secured to lower shell 10,
a gas generator which can readily be manufactured without any
defect and achieves lighter weight can be obtained. In addition, in
the case where positioning portion 38 is formed to have an annular
shape as in the case of Embodiment 1 of the present invention
described above, positioning portion 38 also exhibits the function
as the effluence prevention member. In the case where a plurality
of positioning portions 38 are arranged as aligned intermittently
along the circumferential direction of filter 70, further lighter
weight and lower cost can be achieved.
Embodiment 4
[0088] FIG. 7 is a schematic diagram of a gas generator in
Embodiment 4 of the present invention. In addition, FIG. 8 is a
plan view of a lower shell of the gas generator shown in FIG. 7. A
gas generator 1D in the present embodiment will be described below
with reference to these FIGS. 7 and 8.
[0089] As shown in FIGS. 7 and 8, gas generator 1D in the present
embodiment is different from gas generator 1A in Embodiment 1 of
the present invention described above in a shape of lower shell 10
and a structure for assembly of igniter 40 to lower shell 10.
Specifically, in gas generator 1D in the present embodiment, a
holding portion 30 formed from a resin-molded portion is provided
in lower shell 10 and igniter 40 is attached to holding portion 30,
so that igniter 40 is assembled to lower shell 10.
[0090] More specifically, as shown in FIG. 7, in gas generator 1D
in the present embodiment, lower shell 10 is made of a press-formed
product formed by press-working one plate-shaped member made of
metal. A protruding cylindrical portion 17 protruding toward top
plate portion 21 is provided in a substantially central portion of
bottom plate portion 11 of lower shell 10, so that a depression
portion 18 is formed in the substantially central portion of bottom
plate portion 11 of lower shell 10. Protruding cylindrical portion
17 is a site to which igniter 40 is fixed with holding portion 30
being interposed, and depression portion 18 is a site serving as a
space for providing a female connector portion 36 in holding
portion 30. Here, protruding cylindrical portion 17 is formed to be
in a cylindrical shape with bottom, and tapered such that an outer
diameter thereof decreases toward top plate portion 21. In
addition, opening 15 is provided at an axial end portion of
protruding cylindrical portion 17, which is located on a side of
top plate portion 21. Opening 15 is a site through which a pair of
terminal pins 42 of igniter 40 is inserted.
[0091] As described above, lower shell 10 is fabricated by
press-working one plate-shaped member made of metal. Specifically,
lower shell 10 is fabricated by using a pair of molds consisting of
an upper mold and a lower mold to press one plate-shaped member
made of metal in a vertical direction to thereby form the
plate-shaped member in a shape as illustrated.
[0092] Here, for example, a metal plate composed of stainless
steel, iron steel, an aluminum alloy, a stainless alloy, or the
like and having a thickness before pressing approximately not
smaller than 1.5 mm and not greater than 3.0 mm is made use of as
the plate-shaped member made of metal, and suitably, what is called
a high tensile steel plate which is free from such breakage as
fracture even at the time of application of tensile stress not
lower than 440 MPa and not higher than 780 MPa is suitably made use
of. It is noted that, regarding a thickness after pressing, a
thickness of a smallest thickness portion is preferably not smaller
than approximately 1.0 mm. In addition, press-working may be
carried out through hot forging or cold forging, and from a point
of view of improvement in dimension accuracy, it is more suitably
carried out through cold forging.
[0093] Holding portion 30 described above is provided around
protruding cylindrical portion 17 provided in the substantially
central portion of bottom plate portion 11 of lower shell 10.
Holding portion 30 has an inner coating portion 31 covering a part
of an inner surface of bottom plate portion 11 of lower shell 10,
an outer coating portion 32 covering a part of an outer surface of
bottom plate portion 11 of lower shell 10, and a coupling portion
33 located within opening 15 provided in bottom plate portion 11 of
lower shell 10 and continuing to each of inner coating portion 31
and outer coating portion 32.
[0094] This holding portion 30 is formed from a resin-molded
portion formed by attaching an insulating fluid resin material to
bottom plate portion 11 so as to reach a part of the outer surface
of bottom plate portion 11 from a part of the inner surface thereof
through opening 15 provided in bottom plate portion 11 of lower
shell 10 and solidifying the fluid resin material. Namely, holding
portion 30 is formed by injection molding with the use of a mold
(more particularly, outsert molding).
[0095] For a source material for holding portion 30 formed by
injection molding, a resin material excellent in heat resistance,
durability, corrosion resistance, and the like after curing is
suitably selected and made use of. In that case, without being
limited to a thermosetting resin represented by an epoxy resin and
the like, a thermoplastic resin represented by a polybutylene
terephthalate resin, a polyethylene terephthalate resin, a
polyamide resin (such as nylon 6 or nylon 66), a polypropylene
sulfide resin, a polypropylene oxide resin, and the like can also
be made use of. In a case where these thermoplastic resins are
selected as a source material, in order to ensure mechanical
strength of holding portion 30 after molding, glass fibers or the
like are preferably contained as fillers in these resin materials.
In a case where sufficient mechanical strength can be ensured only
by a thermoplastic resin, however, a filler as described above does
not have to be added.
[0096] Holding portion 30 is secured to bottom plate portion 11 at
a surface on a side of bottom plate portion 11, of each of inner
coating portion 31, outer coating portion 32, and coupling portion
33 described above. Here, holding portion 30 is provided to
entirely cover protruding cylindrical portion 17 provided in bottom
plate portion 11 of lower shell 10, so that protruding cylindrical
portion 17 is completely buried in holding portion 30.
[0097] In a portion of inner coating portion 31 of holding portion
30, which is opposed to top plate portion 21, a holding wall
portion 34 having an annular shape is erected toward top plate
portion 21, so that an accommodation recess portion 35 is provided
in holding portion 30. Accommodation recess portion 35 is a site
for receiving and accommodating a part of igniter 40.
[0098] Igniter 40 is an ignition device producing flame and thermal
particles for burning gas generating agent 61 and assembled to
holding portion 30 as a part thereof is accommodated in
accommodation recess portion 35 described above. Here, unlike the
igniter in Embodiment 1 of the present invention described above,
igniter 40 equipped in gas generator 1D in the present embodiment
is an igniter of a type in which an ignition agent and an enhancer
agent are loaded in agent loaded portion 41.
[0099] Igniter 40 includes agent loaded portion 41 in which an
agent generating flame and thermal particles as it burns is loaded
and a pair of terminal pins 42 described above. Agent loaded
portion 41 contains an ignition agent generating flame as it is
ignited and burns at the time of actuation, a resistor for igniting
this ignition agent, and an enhancer agent producing a large number
of thermal particles as it is ignited by the flame caused by
burning of the ignition agent and it burns. The pair of terminal
pins 42 is connected to agent loaded portion 41 for igniting the
ignition agent.
[0100] More specifically, igniter 40 includes an igniter cup 41c
made of a cup-shaped member, base portion 41b which closes an
opening end of igniter cup 41c and holds the pair of terminal pins
42 as the pins are inserted therethrough, and cover portion 44
provided to cover a part of terminal pin 42 and base portion 41b,
and has such a construction that the resistor (bridge wire) is
attached to couple tip ends of the pair of terminal pins 42
inserted in igniter cup 41c to each other, the ignition agent is
loaded into igniter cup 41c so as to surround or be proximate to
this resistor, and the enhancer agent is loaded to be in contact
with the ignition agent. It is noted that igniter cup 41c is
generally made of metal or plastic.
[0101] Upon sensing collision, a prescribed amount of current flows
in a resistor through terminal pin 42. As the prescribed amount of
current flows in the resistor, Joule heat is generated in the
resistor and the ignition agent starts burning. Flame at a high
temperature caused by burning burns the enhancer agent and produces
a large number of thermal particles. As the enhancer agent burns, a
pressure and a temperature within igniter cup 41c increase, igniter
cup 41c bursts or melts, and the thermal particles are released to
the outside of igniter 40.
[0102] Holding wall portion 34 having an annular shape defining
accommodation recess portion 35 of holding portion 30 is provided
with a plurality of locking pawl portions 34a provided to align
along a circumferential direction at an end portion thereof on the
side of top plate portion 21, and locking pawl portions 34a are all
formed such that their tip ends face inward. The plurality of
locking pawl portions 34a are sites corresponding to a locking
portion for fixing igniter 40 to holding portion 30, which are
integrally provided simultaneously with other sites of holding
portion 30 at the time of injection molding of holding portion 30.
Therefore, the plurality of locking pawl portions 34a are all
elastically deformable, and holding wall portion 34 itself is
elastically deformable.
[0103] On the other hand, cover portion 44 of igniter 40 is
provided with a site of which outer shape is formed to be greater
than agent loaded portion 41 (that is, a site extending radially
outward), and the site corresponds to a locked portion for fixing
igniter 40 to holding portion 30. The site extends annularly along
a circumferential direction, and includes inclined upper surface
and lower surface and a circumferential surface continuing to these
upper surface and lower surface.
[0104] In assembly, while holding portion 30 formed from the
resin-molded portion is formed in advance by injection molding in
bottom plate portion 11 of lower shell 10 and sealing member 50 is
accommodated within accommodation recess portion 35 of holding
portion 30, igniter 40 is inserted in accommodation recess portion
35 from above (that is, the side of top plate portion 21 after
assembly). Here, a pair of terminal pins 42 of igniter 40 is
inserted in a pair of insertion holes 37 provided in coupling
portion 33 of holding portion 30.
[0105] Here, locking pawl portions 34a of holding portion 30 come
in contact with the inclined lower surface of cover portion 44 of
igniter 40. As described above, however, since locking pawl
portions 34a and holding wall portion 34 are elastically
deformable, locking pawl portions 34a and holding wall portion 34
retract radially outward, so that cover portion 44 of igniter 40
can be inserted in accommodation recess portion 35.
[0106] Then, after igniter 40 is inserted in holding portion 30,
locking pawl portions 34a go beyond a side portion of cover portion
44 so that locking pawl portions 34a and holding wall portion 34
return to their original shapes and locking pawl portions 34a are
locked to the inclined upper surface of cover portion 44 described
above. Thus, igniter 40 is fitted in accommodation recess portion
35 while cover portion 44 thereof is accommodated in accommodation
recess portion 35 of holding portion 30, and thus igniter 40 is
held by holding portion 30.
[0107] In a portion of outer coating portion 32 of holding portion
30, which faces the outside, female connector portion 36 is formed.
This female connector portion 36 is a site for receiving a male
connector (not shown) of a harness for connecting igniter 40 and a
control unit (not shown) to each other, and it is located in
depression portion 18 provided in bottom plate portion 11 of lower
shell 10. In this female connector portion 36, a portion of
terminal pin 42 of igniter 40 closer to a lower end is arranged as
being exposed. The male connector is inserted in female connector
portion 36, so that electrical conduction between a core wire of
the harness and terminal pin 42 is established.
[0108] A pair of insertion holes 37 is provided in coupling portion
33 of holding portion 30. This pair of insertion holes 37 is a site
through which a pair of terminal pins 42 of igniter 40 is inserted,
and opposing ends thereof reach accommodation recess portion 35 and
female connector portion 36 described above, respectively.
[0109] In addition, as shown in FIGS. 7 and 8, separately from a
holding portion main body constituted of inner coating portion 31,
outer coating portion 32, and coupling portion 33 described above,
holding portion 30 is provided with an extended portion 38c
extending radially outward of the housing along the inner surface
of bottom plate portion 11 from the holding portion main body.
Extended portion 38c reaches the axial end portion of filter 70
located on the side of bottom plate portion 11, and abutment
portion 38a serving as positioning portion 38 is provided at the
tip end of extended portion 38c. Extended portion 38c has an
annular disc-shaped shape and it also serves as the margin for
securing for positioning portion 38 as it is secured to bottom
plate portion 11.
[0110] Positioning portion 38 is provided in a portion of bottom
plate portion 11 of lower shell 10, which faces combustion chamber
60, and abutment portion 38a abuts to the inner circumferential
surface of the axial end portion of filter 70 located on the side
of bottom plate portion 11. Positioning portion 38 has an annular
shape so as to abut to filter 70 along the circumferential
direction of filter 70.
[0111] Here, as in the case of Embodiment 1 of the present
invention described above, positioning portion 38 is a site for
positioning of filter 70 in a radial direction during assembly of
filter 70 to lower shell 10, and it is formed integrally with the
holding portion main body at the time of injection molding of the
holding portion main body of holding portion 30 described above.
Therefore, positioning portion 38 is formed by injection molding
with the use of a mold (more particularly, outsert molding).
[0112] In the case of gas generator 1D in the present embodiment
described above as well, an effect substantially the same as in the
case of gas generator 1A in Embodiment 1 of the present invention
described above can be obtained. Namely, since positioning portion
38 is formed by injection molding while it is secured to lower
shell 10, a gas generator which can readily be manufactured without
any defect and achieves lighter weight can be obtained. In
addition, since positioning portion 38 is formed to have an annular
shape as in the case of Embodiment 1 of the present invention
described above, positioning portion 38 also exhibits the function
as the effluence prevention member, and a gas generator comparable
in terms of performance to the conventional gas generator including
a plate-shaped member made of metal for the effluence prevention
member can be obtained.
[0113] In addition, with gas generator 1D in the present
embodiment, since positioning portion 38 is formed integrally with
holding portion 30, a plate-shaped member made of metal as an
independent part which has conventionally been required is no
longer necessary. Thus, the number of parts can consequently be
reduced and an assembly process is simplified, so that
manufacturing cost can be reduced as compared with the conventional
example and a gas generator can inexpensively be manufactured.
[0114] Moreover, with gas generator 1D in the present embodiment,
since positioning portion 38 can be provided integrally with the
holding portion main body of holding portion 30 for holding igniter
40, it is not necessary to form only positioning portion 38
separately by injection molding and a manufacturing process can
also be simplified.
[0115] FIG. 9 is a plan view of a lower shell of a gas generator
according to a first variation based on the present embodiment. The
gas generator according to the first variation based on the present
embodiment will now be described with reference to this FIG. 9.
[0116] In gas generator 1D in the present embodiment described
above, extended portion 38c is formed from an annular disc-shaped
site. In the gas generator according to the present variation,
however, extended portions 38c are formed from a plurality of sites
each in a long flat plate shape radially extending from the holding
portion main body as shown in FIG. 9. Then, the construction is
such that, at tip end portions located radially outward of the
plurality of extended portions 38c, abutment portion 38a having an
annular shape as continuing to the tip end portions is provided and
positioning portion 38 is formed from the plurality of extended
portions 38c and abutment portion 38a having an annular shape.
[0117] In the case of such a construction as well, an effect the
same as in the case of gas generator 1D in the present embodiment
described above can be obtained and an amount of resin material
used for forming extended portion 38c can be reduced. Thus, a gas
generator of lighter weight can be manufactured more
inexpensively.
[0118] In addition, in the case where the construction above is
adopted, as compared with a case of gas generator 1D in the present
embodiment described above, positioning portion 38 is no longer
arranged in combustion chamber 60. Therefore, an effect that an
amount of filling with gas generating agent 61 can accordingly be
increased or a gas generator can accordingly be reduced in size can
also be obtained.
[0119] FIG. 10 is a plan view of a lower shell of a gas generator
according to a second variation based on the present embodiment.
The gas generator according to the second variation based on the
present embodiment will now be described with reference to this
FIG. 10.
[0120] In gas generator 1D in the present embodiment described
above, extended portion 38c is formed from a site in an annular
disc-shaped shape and abutment portion 38a is formed from a site in
an annular shape. In the gas generator according to the present
variation, as shown in FIG. 10, extended portions 38c are formed
from a plurality of sites each in an elongated flat plate shape
radially extending from the holding portion main body, and at tip
end portions located radially outward of the plurality of extended
portions 38c, abutment portions 38a are individually provided as
continuing to the tip end portions. Thus, the construction is such
that a plurality of abutment portions 38a are arranged as aligned
intermittently along the circumferential direction of filter 70 and
positioning portion 38 is formed from the plurality of extended
portions 38c and the plurality of abutment portions 38a.
[0121] In the case of such a construction as well, an effect the
same as in the case of gas generator 1D in the present embodiment
described above can be obtained. It is noted that, in the present
variation, since the construction is such that the inner
circumferential surface of the axial end portion of filter 70
located on the side of bottom plate portion 11 is partly not
covered with positioning portion 38, positioning portion 38 does
not exhibit a function as the effluence prevention member described
above. In a case where gas discharge opening 23 is provided at a
position relatively closer to the upper end portion of
circumferential wall portion 12, 22 of the housing, a case where
mechanical strength of lower shell 10 is sufficiently high, or the
like, however, there may also originally be no possibility that the
gas flows out from between filter 70 and lower shell 10, and in
that case, an amount of resin material used for forming positioning
portion 38 can be reduced by adopting the construction as in the
present variation and a gas generator of lighter weight can be
manufactured more inexpensively.
[0122] In addition, in the case where the construction above is
adopted, as compared with a case of gas generator 1D in the present
embodiment described above, positioning portion 38 is no longer
arranged in combustion chamber 60, so that an effect that an amount
of filling with gas generating agent 61 can accordingly be
increased or a gas generator can accordingly be reduced in size can
also be obtained.
Embodiment 5
[0123] FIG. 11 is a schematic diagram of a gas generator in
Embodiment 5 of the present invention. In addition, FIG. 12 is a
plan view of a lower shell of the gas generator shown in FIG. 11. A
gas generator 1E in the present embodiment will be described below
with reference to these FIGS. 11 and 12.
[0124] As shown in FIGS. 11 and 12, gas generator 1E in the present
embodiment is different from gas generator 1D in Embodiment 4 of
the present invention described above in a shape of positioning
portion 38. Specifically, in gas generator 1E in the present
embodiment, positioning portion 38 further has an extended
protruding portion 38d extending to further protrude radially
outward of the housing along the inner surface of bottom plate
portion 11 as continuing to the tip end portion located radially
outward of extended portion 38c, in addition to abutment portion
38a and extended portion 38c described above. Extended protruding
portion 38d abuts to an end surface of the axial end portion of
filter 70 located on the side of bottom plate portion 11 and is
sandwiched between filter 70 and bottom plate portion 11. It is
noted that extended protruding portion 38d has an annular
disc-shape so as to abut to filter 70 along the circumferential
direction of filter 70.
[0125] In the case of gas generator 1E in the present embodiment
described above as well, an effect the same as in the case of gas
generator 1D in Embodiment 4 of the present invention described
above can be obtained. Namely, since positioning portion 38 is
formed by injection molding while it is secured to lower shell 10,
a gas generator which can readily be manufactured without any
defect and achieves lighter weight can be obtained. In addition,
since positioning portion 38 is formed to have an annular shape as
in the case of Embodiment 4 of the present invention described
above, positioning portion 38 also exhibits the function as the
effluence prevention member, and a gas generator comparable in
terms of performance to the conventional gas generator including a
plate-shaped member made of metal for the effluence prevention
member can be obtained. Moreover, since positioning portion 38 is
formed integrally with holding portion 30 as in the case of
Embodiment 4 of the present invention described above, a
plate-shaped member made of metal as an independent part which has
conventionally been required is no longer necessary. Thus, the
number of parts can be reduced and an assembly process is
simplified, so that manufacturing cost can consequently be reduced
as compared with the conventional example and a gas generator can
inexpensively be manufactured. Furthermore, as in the case of
Embodiment 4 of the present invention described above, since
positioning portion 38 can be provided integrally with the holding
portion main body of holding portion 30 for holding igniter 40, it
is not necessary to form only positioning portion 38 separately by
injection molding and a manufacturing process can also be
simplified.
[0126] Additionally, with gas generator 1E in the present
embodiment, hermeticity of combustion chamber 60 located in the
housing can further be enhanced. Namely, in gas generator 1E in the
present embodiment, the construction is such that extended portion
38c is in an annular disc-shaped shape and extended protruding
portion 38d located radially outward of extended portion 38c and
having an annular disc-shaped shape is sandwiched between filter 70
and bottom plate portion 11 of lower shell 10 around the entire
circumference in the circumferential direction. Therefore, not only
a long distance between combustion chamber 60 and an external space
via an interface portion located between lower shell 10 and holding
portion 30 can be ensured, but also intimate contact between
holding portion 30 and lower shell 10 in a portion where extended
protruding portion 38d is provided is improved by sandwiching
above, so that sealability at that site drastically improves.
Therefore, occurrence of such a defective condition as moisture
absorption by gas generating agent 61 can be prevented and a highly
reliable gas generator can be obtained.
Embodiment 6
[0127] FIG. 13 is a schematic diagram of a gas generator in
Embodiment 6 of the present invention. A gas generator 1F in the
present embodiment will be described below with reference to this
FIG. 13.
[0128] As shown in FIG. 13, gas generator 1F in the present
embodiment is different from gas generator 1D in Embodiment 4 of
the present invention described above in a structure for assembly
of igniter 40 to lower shell 10. Specifically, in gas generator 1F
in the present embodiment, igniter 40 is assembled integrally to
holding portion 30 at the time of injection molding of holding
portion 30 formed from the resin-molded portion provided in lower
shell 10. Namely, in the present embodiment, igniter 40 is
assembled to lower shell 10 by insert molding and a part of holding
portion 30 is secured to the surface of igniter 40. It is noted
that positioning portion 38 is formed integrally with the holding
portion main body at the time of injection molding of the holding
portion main body of holding portion 30 described above, as in the
case of gas generator 1D in Embodiment 4 of the present invention
described above.
[0129] In the case of gas generator 1F in the present embodiment
described above as well, an effect the same as in the case of gas
generator 1D in Embodiment 4 of the present invention described
above can be obtained. Namely, since positioning portion 38 is
formed by injection molding while it is secured to lower shell 10,
a gas generator which can readily be manufactured without any
defect and achieves lighter weight can be obtained. In addition,
since positioning portion 38 is formed to have an annular shape as
in the case of Embodiment 4 of the present invention described
above, positioning portion 38 also exhibits the function as the
effluence prevention member, and a gas generator comparable in
terms of performance to the conventional gas generator including a
plate-shaped member made of metal for the effluence prevention
member can be obtained. Moreover, since positioning portion 38 is
formed integrally with holding portion 30 as in the case of
Embodiment 4 of the present invention described above, a
plate-shaped member made of metal as an independent part which has
conventionally been required is no longer necessary. Thus, the
number of parts can be reduced and an assembly process is
simplified, so that manufacturing cost can consequently be reduced
as compared with the conventional example and a gas generator can
inexpensively be manufactured. Furthermore, as in the case of
Embodiment 4 of the present invention described above, since
positioning portion 38 can be provided integrally with the holding
portion main body of holding portion 30 for holding igniter 40, it
is not necessary to form only positioning portion 38 separately by
injection molding and a manufacturing process can also be
simplified.
[0130] Characteristic features of the gas generators according to
Embodiments 1 to 6 and variations thereof of the present invention
described above can naturally be combined with one another within
the scope allowable in light of the gist of the present invention.
Furthermore, a specific shape, the number, a size, or the like of
positioning portion(s) provided in a lower shell described above
can also naturally be modified as appropriate.
[0131] Thus, each embodiment and a variation thereof above
disclosed herein are illustrative and non-restrictive in every
respect. The technical scope of the present invention is delimited
by the terms of the claims and is intended to include any
modifications within the scope and meaning equivalent to the terms
of the claims.
REFERENCE SIGNS LIST
[0132] 1A to 1F gas generator; 10 lower shell; 11 bottom plate
portion; 12 circumferential wall portion; 13 attachment portion;
13a, 13b crimping portion; 14 accommodation recess portion; 15
opening; 16 female connector portion; 17 protruding cylindrical
portion; 18 depression portion; 19 curved corner portion; 20 upper
shell; 21 top plate portion; 22 circumferential wall portion; 23
gas discharge opening; 24 sealing member; 30 holding portion; 31
inner coating portion; 32 outer coating portion; 33 coupling
portion; 34 holding wall portion; 34a locking pawl portion; 35
accommodation recess portion; 36 female connector portion; 37
insertion hole; 38 positioning portion; 38a, 38a1, 38a2 abutment
portion; 38b margin for securing; 38c extended portion; 38d
extended protruding portion; 40 igniter; 41 agent loaded portion;
41a squib cup; 41b base portion; 41c igniter cup; 42 terminal pin;
44 cover portion; 46 enhancer cup; 46a flange portion; 47 enhancer
chamber; 48 enhancer agent; 50 sealing member; 60 combustion
chamber; 61 gas generating agent; 62 supporting member; 64 cushion
material; and 70 filter.
* * * * *