Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-09-22
2001-03-06
Mar, Michael (Department: 3619)
Land vehicles
Wheeled
Attachment
C280S741000
Reexamination Certificate
active
06196582
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to vehicle supplemental inflatable restraint systems and, more particularly, to an air bag inflator that provides variable output inflation of an air bag.
BACKGROUND OF THE INVENTION
Driver side or passenger side supplemental inflatable restraint (SIR) systems typically include an air bag stored in a housing module within the interior of the vehicle in close proximity to either the driver or one or more passengers. SIR systems are designed to actuate upon sudden deceleration so as to rapidly deploy an air bag to restrain the movement of the driver or passengers. During deployment, gas is emitted rapidly from an inflator into the air bag to expand it to a fully inflated state.
Air bag passive restraint systems include an inflator, which produces gas to inflate the air bag cushion. Known inflators for air bag modules are generally of three types. One type is the pure gas inflator wherein a pressure vessel contains stored pressurized gas. The pressure vessel communicates with the cushion through various types of rupturable outlets or diaphragms. Another type is the gas generator wherein a propellant is ignited and the resultant gas flow through an outlet to the cushion. A third type is the hybrid or augmented type. This type includes a pressure vessel containing stored pressurized gas and a gas generator. When the generator is ignited, the resultant gas flows with the stored gas to the cushion through the pressure vessel outlet.
It is also known to inflate the cushion at a relatively low rate under low level deployment conditions, such as a sudden low level deceleration, and at a relatively high rate under high level deployment conditions, such as a sudden high level deceleration. This can be accomplished in a pure gas type inflator by providing the pressure vessel with an outlet of variable flow area. In addition, devices are known which provide primary inflation (reduced inflation) and full level inflation using a single gas vessel with two separate gas heaters. Primary inflation is accomplished by actuating the gas vessel and heating the gas at a specified reduced level. Full level inflation is accomplished by actuating a second separate heater located at the bottom of the gas vessel to heat the gas at a greater level. This second heater is deployed at the same time or a delayed time as the primary heater to provide full level inflation. It is also known in the art to use a system having two discrete inflators to accomplish dual level inflation. In these types of systems, two discrete inflators are deployed at the same time or at a delayed time depending upon the severity of the sudden deceleration.
SUMMARY OF THE INVENTION
This invention offers advantages and alternatives over the prior art by providing an inflator which provides for variable output inflation of an air bag cushion in response to full or reduced level deployment conditions. The inflator of the present invention includes a first chamber for storing an inert gas, a second chamber in fluid communication with the first chamber, and a third chamber in selective fluid communication with the second chamber, wherein the third chamber stores a heat modifier for varying a heat value of the inert gas. The inflator also includes a pyrotechnic device having a combustible material for heating the inert gas and a first initiator for actuating the pyrotechnic device upon first and second deployment conditions. A second initiator for opening the third chamber to the second chamber is provided wherein actuation of the second initiator causes the heat modifier to fluidly communicate with the combustible material and vary the heat value of the inert gas during a combustion process. The second initiator is actuated during second deployment conditions. The inflator also includes a diffuser having a vent port for releasing the heated inert gas from the inflator to the air bag cushion.
The heat modifer is preferably selected from the group consisting of accelerants, inhibitors, and catalysts. When the heat modifier comprises an accelerant, the output inflation under first level deployment conditions is less than the output inflation under second level deployment conditions because the accelerant creates additional heat during the pyrotechnic process causing greater gas expansion. Likewise, when the heat modifier comprises a catalyst, the output inflation under first level deployment conditions is less than the output inflation under second level deployment conditions because the catalyst causes the combustible material in the pyrotechnic device to increase its reaction rate without adding material to the mass balance. This causes the pressure of the heated inert gas to increase resulting in an increase in gas expansion. In a third embodiment, when the heat modifier comprises an inhibitor, the output inflation under first level deployment is greater than the output inflation under second level deployment conditions because the inhibitor reduces the heat value added to the stored inert gas and thus decreases the gas expansion.
Accordingly, in the first and second embodiments, the inflator has a primary low level of operation because the actuation of the first initiator results only in low level deployment of the air bag cushion. To increase the level of deployment, the second initiator is actuated causing either the accelerant or catalyst to be introduced into the second chamber and combined with the pyrotechnic material during the combustion process. In contrast, the inflator, in the third embodiment, has a primary high level of operation because the actuation of the first initiator results in a high level of deployment and the actuation of the second initiator reduces the level of deployment. Accordingly, the present invention provides a variable output inflator where the level of output is variable in response to the inflator receiving an additional actuation signal from a control system, including the controller. Advantageously, the inflator of the present invention offers a low cost method of producing a variable output inflator for use with an air bag module and the ability to offer multiple inflator outputs from a single inflator body reduces package size, module costs, and module complexity.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.
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Niederman Robert Raymond
Ryan Shawn Gregory
Sparkman John Paul
Starner Allen Richard
Delphi Technologies Inc.
Jasmin Lynda
Mar Michael
Marra Kathryn A.
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