Ammunition and explosives – Igniting devices and systems – Electrical primer or ignitor
Reexamination Certificate
2002-04-12
2004-11-30
Jordan, Charles T. (Department: 3644)
Ammunition and explosives
Igniting devices and systems
Electrical primer or ignitor
C102S530000
Reexamination Certificate
active
06823796
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a gas generator for actuating a seat belt pretensioner of an automobile.
BACKGROUND ART
A seat belt pretensioner is known as a safety system for protecting occupants in an automobile from an impact generated in a collision of the automobile. The pretensioner is actuated by a large amount of gas introduced by a gas generator and subsequently protects the occupants. The gas generator includes a squib as an ignitor, gas generants and the like. The gas generator ignites the squib in the collision, thereby fires and burns the gas generants then generates a large amount of gas rapidly.
As an example of conventional gas generators, a gas generator shown in
FIG. 11
has been proposed. The gas generator shown in
FIG. 11
includes a cup body
51
in a shape of cylinder with a bottom loaded with gas generants
52
, a tube body
54
housing firing agents
53
, and a holder
55
of which some parts are fitted in the cup body
51
and th tube body
54
respectively to seal the cup body
51
containing the gas generants
52
in its inside and the tube body
54
containing the firing agents
53
in its inside. The holder
55
is made of resin. The holder
55
is integrally provided with a squib
56
for igniting the firing agents
53
. The squib
56
includes two electrode pins
57
,
58
penetrating the holder
55
and projecting within the tube body
54
, a bridge wire
59
welded to the respective electrode pins
57
,
58
in the tube body
54
, and an igniting agent ball
60
covering the bridge wire
59
and being in contact with the firing agents
53
.
In this gas generator, the parts of the holder
55
is inserted in an opening of the cup body
51
. An end portion of the cup body
51
on the opening side is caulked in caulking groove
63
so that the end portion comes into contact with a sealing ring
61
flexibly in the caulking groove
63
of the holder
55
. Thus, the cup body
51
is sealed by the holder
55
. Further, an end portion on an opening side or the tube body
54
is supported on the holder
55
by means of an inner cylindrical member
62
fitted in the cap body
51
. As a result, the tube body
54
comes into close contact with the holder
55
then an inside space of the tube body
54
is tightly shut out,
In the gas generator of the above-mention d construction, when electric current is passed through the respective electrode pins
57
,
58
of the squib
56
, the bridge wire
59
generates heat then the igniting agent ball
60
ignites. The igniting agent ball
60
fires the firing agents
53
. A flame of ignition of the squib
56
is ejected into the cup body
51
. The gas generants
52
are ignited and burned by the flame then a large amount of gas generates rapidly.
However, since this type of conventional gas generator has a construction where the cup body
51
and the holder
55
are sealed by the caulking portion, there is an adverse possibility that a caulking force acts on the holder
55
then the holder
55
is deformed. A lack of high accuracy in the caulking position of the cup body
51
causes direct press and deformation to the holder. The deformation of the holder
55
generates gaps between the holder
55
and the respective electrode pins
57
,
58
and the like. Water and the like go into the tube body
54
from the gaps then deteriorate the firing agents
54
, the igniting agent ball
60
and the like. Therefore, performance of the gas generator is not ensured over a long period of time of use.
Further, the cup body
51
and the holder
65
are sealed by caulking portion of the cup body
51
and the sealing ring and the like, and the tube body
54
and the holder
55
are sealed by a cup member
62
. Therefore, a number of members for sealing the above-mentioned components increases. As a result, cost of manufacture of the gas generators cannot be reduced.
It is an object of the present invention to provide a gas generator for use in occupant safety systems such as seat belt pretensioner, which has excellent durability, and of which cost of manufacture is reduced.
DISCLOSURE OF THE INVENTION
A gas generator comprises a cup body loaded with gas generants generating gas by combustion, a tube body arranged inside of the cup body to contain firing agents ignited by electric current, a holder made of resin and fitted in both the cup body and the tube body for enclosing the gas generants and the firing agents, and a reinforcement is integrated with the resin of the holder by insert molding.
According to the present invention having the above described construction, even when the holder is made of resin, a deformation of the holder caused by a caulking force for connecting the cup body to the holder is restrained by the reinforcement. Also, a deformation of the holder caused by thermal expansion is restrained by the reinforcement.
Therefore, the invention prevents gaps that arise by deformation of the holder, whereby water and the like do not enter the tube body. As a result, performance of the gas generator is ensured over a long period of time of use.
Further, the gas generator of the present invention is preferably constructed as follows. The reinforcement has a protruding portion from an outer periphery of the holder. The protruding portion is fitted into the cup body. Inter-gaps among the cup body, the tube body and the holder are tightly closed by means of a caulking force between the protruding portion and the cup body.
Since the caulking force acts between the cup body and the protruding portion of the reinforcement, high accuracy in the caulking position is not required. Since a simple caulking construction between the cup body and the reinforcement enables the inter-gaps among the cup body, the tube body and the holder to be integrally and tightly closed, the number of sealing members such as sealing rings is decreased. Also, the strength of the holder is increased by the reinforcement. Therefore, a gas generator can be provided, which has excellent durability and for which the cost of manufacturing is reduced.
Additionally, the gas generator of the present invention is preferably constructed as follows. The tube body has a flange protruding towards the cup body, the flange is sandwiched in between the cup body and the protruding portion of the reinforcement.
The reinforcement restrains that the caulking force from acting on the resin of the holder directly, and prevents the holder from deforming.
Also, the gas generator of the present invention is preferably constructed as follows. The reinforcement consists of a cylindrical body and a ring plate body so as to have a cup shape. The cylindrical body protrudes from the outer periphery of the holder. The ring plate body is integrated with the resin of the holder.
The reinforcement constructed above enables the strength of the holder to increase, and the connecting the cup body to the holder with caulking to be done easily.
Another gas generator of the present invention comprises a cup body loaded with gas generants generating gas by combustion, a tube body arranged inside of the cup body to contain firing agents ignited by electric current, a holder made of resin and fitted in both the cup body and the tube body for enclosing the gas generants and the firing agents, and a ring body mounting fixedly on a part of outer periphery of the holder so that an inter-gap between the cup body and the holder is tightly closed.
According to the present invention having the above described construction, high accuracy in a caulking position between the cup body and the holder is not required. The inter-gap between the cup body and the holder is tightly closed by means of a simple operation in which the ring body is mounted fixedly on the part of the outer periphery of the holder.
In addition, according to the present invention, since the caulking force does not act on the cup body directly, the caulking force is restrained from acting on the resin of the holder through the cup body. Deformation of the holder is thereby prevented.
As a result, the cost for manufact
Jordan Charles T.
Nguyen T.
Nippon Kayaku Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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