Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-10-07
2001-03-20
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S742000
Reexamination Certificate
active
06203061
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to vehicle supplemental inflatable restraint systems and, more particularly, to an air bag module that provides variable output inflation of an air bag cushion from a single inflator.
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.
It is desirable to provide an air bag module which utilizes utilizes a single stage inflator and a simple air bag cushion and which is capable of variable air bag cushion inflation.
SUMMARY OF THE INVENTION
This invention offers advantages and alternatives over the prior art by providing an air bag sub-module which offers variable deployment performance by controlling the heat content of the inflator gas which exits the air bag sub-module into the air bag cushion. The air bag sub-module includes a sub-module housing which receives an inflator in a central cavity formed therein. The inflator is provided for generating inflator gas for inflation of an air bag cushion and the inflator has inflator discharge ports to permit the generated inflator gas to flow from the inflator with the sub-module housing. The inflator includes a first initiator which upon actuation ignites pyrotechnic material to generate the inflator gas. The air bag sub-module includes low output module ports formed in the sub-module housing and high output module ports also formed therein at one end. Heat sinking material is disposed within the sub-module housing between an outer wall of the sub-module housing and the inflator such that the heat sinking material surrounds the low output module ports.
A slide or stopper mechanism is provided at an end of the sub-module housing opposite the first initiator, wherein the mechanism include a second initiator and a projectile which is driven by pressure generated by the second initiator upon actuation thereof. The sub-module housing includes an inner wall which partitions the internal cavity of the sub-module housing so that the inflator is on one side of the inner wall and the high output module ports are on the opposite side of the inner wall. In the illustrated embodiment, the inner wall comprises an annular wall. The inner wall includes an opening which is sized to receive the projectile in a gas tight manner when the second initiator is actuated to drive the projectile toward the inflator.
According to the present invention, the air bag sub-module provides a first fluid flow path for the heated inflator gas to flow under first deployment conditions (high level deployment conditions) and a second fluid flow path for the inflator gas to flow under second deployment conditions (reduced level deployment conditions). The first fluid flow path comprises a low resistance fluid flow path in which the heated inflator gas exits the inflator through the inflator ports and travels within the sub-module housing to the high output module ports and into the air bag cushion. Under these first deployment conditions, the second initiator is not actuated and therefore the projectile remains in the retracted position and the inflator gas is permitted to flow between the inflator and the high output module ports. Little or no heated inflator gas will flow through the second fluid flow path, which comprises a high resistance fluid flow path, because in order for the inflator gas to flow according to the second fluid flow path, the inflator gas must pass through the high resistance heat sink material and the low output module ports. Accordingly, the heat content of the inflator gas is not significantly reduced when the inflator gas flows according to the first fluid flow path and the air bag cushion is inflated at a high level of deployment.
Under the second deployment conditions, the second initiator is actuated and the projectile is driven forward toward the inflator and blocks the first fluid flow path. More specifically, the projectile lodges within the opening formed in the inner wall of the sub-module housing and thereby blocks gas from traveling from the inflator ports to the high output module ports. This blockage forces the heated inflator gas to fluidly communicate with the heat sink material and then out through the low output module ports to inflate the air bag cushion. The heat sink material dissipates heat from the heated inflator gas and thus reduces the heat content of the inflator gas. Consequently, the inflator gas has a reduced volume as a result of the reduced heat content of the inflator gas. This results in the air bag cushion being inflated at a reduced level of deployment.
Accordingly, the air bag sub-module of the present invention offers variable output inflation by controlling the heat content of the inflator gas entering the air bag cushion, and therefore the performance characteristics of the air bag sub-module are variable.
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
Spencer Graham Thornton
Starner Allen Richard
Delphi Technologies Inc.
Dickson Paul N.
Marra Kathryn A.
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