Land vehicles – Wheeled – Attachment
Reexamination Certificate
2002-11-27
2004-10-19
Ilan, Ruth (Department: 3616)
Land vehicles
Wheeled
Attachment
C280S736000, C102S531000
Reexamination Certificate
active
06805376
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to an inflator suitable for inflating an airbag or the like for protecting an occupant in a vehicle.
In U.S. Pat. No. 6,273,462, an inflator for inflating an airbag for protecting an occupant in a vehicle has been disclosed. When actuated, an initiator generates a shock wave to open a gas exit.
FIG. 2
is a cross sectional view of the inflator disclosed in U.S. Pat. No. 6,273,462.
An inflator
100
is provided with a substantially cylindrical pressure container
104
having a gas storage
102
filled with a high-pressure gas. A gas jet port
106
formed as a circular opening is provided at an axial end (distal end) of the pressure container
104
. A burst disk
108
formed of a metal sheet or the like closes the gas jet port
106
. The burst disk
108
is adapted to be burst and open the gas jet port
106
when a pressure in the gas storage
102
exceeds a predetermined value, or when an initiator
116
applies a shock wave, which will be described later.
An initiator housing
114
for storing the initiator is provided at the other end (rear end) of the pressure container
104
. The initiator housing
114
has a substantially cylindrical shape projecting from the rear end of the pressure container
104
into the gas storage
102
toward the gas jet port
106
. The initiator
116
for generating a shock wave is installed in the initiator housing
114
.
The initiator
116
is actuated when a pair of electrodes
118
,
120
extending from a rear end thereof for conducting power is energized. The initiator generates a gas with a pressure higher than an internal pressure of the gas storage
102
. A difference in the pressures is sufficient for generating a shock wave in the gas storage
102
. The initiator ejects the high-pressure gas instantaneously from the distal end thereof into the gas storage
102
.
In the inflator
100
thus constructed, when the initiator
116
is actuated and the high-pressure gas is ejected from the initiator
116
into the gas storage
102
, a shock wave is generated in the gas storage
102
due to the pressure difference between the pressure of the gas from the initiator
116
and the pressure of the gas in the gas storage
102
. The shock wave is propagated in the gas storage
102
toward the gas jet port
106
. When the shock wave reaches the burst disk
108
closing the gas jet port
106
, the burst disk
108
is burst due to the shock wave before a total pressure in the gas storage
102
reaches to a bursting pressure of the burst disk
108
, and thus the gas jet port
106
is opened. As a result, the gas is ejected from the inflator
100
.
In the inflator
100
, a substantially cap shaped diffuser
110
is fitted on the gas jet port
106
at the distal end of the pressure container
104
. Therefore, when the burst disk
108
bursts, the gas in the gas storage
102
passes from the gas jet port
106
through the diffuser
110
, and is ejected to the outside through orifices
112
formed on a peripheral side surface of the diffuser
110
.
As described above, in the inflator
100
, the gas is ejected through the jet port
106
when the burst disk
108
is broken before the total gas pressure in the gas storage
102
reaches the burst strength of the burst disk
108
. Thus, the gas with a relatively low pressure may be ejected from the jet port
106
for a relatively long period of time. Consequently, the airbag may be inflated relatively slowly and the internal pressure of the airbag may be maintained at a high level for a relatively long period of time.
In the inflator
100
shown in the
FIG. 2
, the initiator
116
is adapted to generate the shock wave by ejecting the gas toward the inside of the high-pressure gas storage
102
, and thus the initiator
116
is required to have a high-performance to rapidly generate the gas with a pressure sufficiently higher than that of the gas filled in the gas storage
102
. When an initiator having an inferior performance is used, it is possible that the generated shock wave is not strong enough, and thus may not reach the burst disk
108
, or even if it reaches, it may be too weak to burst the burst disk. Therefore, in such a case, it is necessary to shorten a length of the pressure container of the inflator so that the shock wave can reach the burst disk.
It is an object of the present invention to provide an inflator in which a shock wave is generated even when the initiator does not rapidly generate the high-pressure gas as described above, and the shock wave breaks the gas exit of the pressure container to allow the gas to be ejected.
Other objects and advantages of the invention will be apparent from the following disclosure of the invention.
SUMMARY OF THE INVENTION
An inflator according to the present invention includes a pressure container having a gas exit that opens upon receipt of a shock wave at one end and being filled with a high-pressure gas therein, and a shock wave generator provided on the other end of the pressure container for generating the shock wave toward the gas exit. The shock wave generator has a tube and an initiator. The tube has a distal end that is broken when the distal end receives the shock wave from inside. The shock wave passes through the distal end toward the gas exit of the pressure container. The tube is filled with a gas having a pressure lower than that of the high-pressure gas in the pressure container. The initiator is provided at a rear end of the tube for emitting the shock wave into the tube when the inflator is actuated.
In the inflator according to the present invention as described above, when the initiator is actuated, the shock wave is generated in the tube by a pressure difference between the gas generated by the initiator and the gas in the tube. Then, the distal end of the tube that received the shock wave is broken to generate additional shock wave due to the pressure difference between the gas in the tube and the gas in the pressure container. The shock wave propagates rapidly in the pressure container, reaches the gas exit of the pressure container, and breaks the gas exit to open. Accordingly, the gas is ejected from the pressure container.
In the present invention, the initiator is provided in the tube filled with the gas having a relatively low pressure. The initiator ejects the gas toward the inside of the tube to generate the shock wave. Therefore, the shock wave can be generated even when the gas pressure generated upon the actuation of the initiator is lower than that of the initiator
116
in the above-described U.S. Pat. No. 6,273,462. Therefore, it is possible to use the initiator with a simple structure and a low cost.
The inflator of the present invention is preferably provided with a booster for promoting the generation of the shock wave by the initiator in the tube.
The booster includes, for example, a propellant (gas forming agent) that induces a gas generation reaction when the initiator generates the gas. When the initiator generates the gas, the booster generates the gas as well to increase the gas pressure generated by the initiator, thereby promoting the generation of the shock wave in the tube.
With the booster provided in the tube, the initiator can have a lower output to generate the shock wave. Therefore, it is possible to use the initiator with a further simpler structure and a lower cost. Even when a pressure container of relatively high capacity is used, or an internal gas pressure is set at a high value, it is possible to use the initiator that can only generates a relatively low-pressure gas to generate the shock wave strong enough for opening the gas exit of the pressure container.
REFERENCES:
patent: 3807755 (1974-04-01), Mason, Jr.
patent: 5031932 (1991-07-01), Frantom et al.
patent: 5762368 (1998-06-01), Faigle et al.
patent: 6170868 (2001-01-01), Butt et al.
patent: 6273462 (2001-08-01), Faigle et al.
patent: 6296274 (2001-10-01), Stevens et al.
patent: 6584911 (2003-07-01), Bergerson et al.
patent: 6629703 (2003-10-01), Horton et al
Ilan Ruth
Kanesaka Manabu
Takata Corporation
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