Land vehicles – Wheeled – Attachment
Reexamination Certificate
1998-09-21
2001-02-20
English, Peter C. (Department: 3619)
Land vehicles
Wheeled
Attachment
C280S737000, C280S741000
Reexamination Certificate
active
06189922
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an inflator with more than one initiator and more than one propellant charge.
BACKGROUND OF THE INVENTION
Inflators are used in vehicles to inflate air bags or other inflatables. The inflatables are intended to protect the occupant when a vehicle collision occurs. In connection with a certain class of inflators, their manner of operation depends upon whether or not the collision involving the vehicle is detected as a high impact or a low impact vehicle collision. The air bag of such an inflator is designed to inflate when a special impact to the vehicle occurs or is exceeded. Different vehicle impacts can occur. A low impact collision typically occurs when the impact vehicle is traveling at a relatively low rate of speed. Relatedly, a low impact collision can occur when an impacting vehicle is traveling at relatively low rate of speed when it strikes the impacted vehicle. Conversely, a high impact collision is characterized by one or both of an impacted and impacting vehicle traveling at a relatively high rate of speed. The pressure developed in the air bag need not be the same for the low and high impact collisions. When a high impact collision occurs, it is desirable to inflate the air bag to a relatively high pressure. With a low impact collision, on the other hand, it is desirable to inflate the air bag to a lesser pressure. Relatedly, depending on the age and/or size of the vehicle occupant, it may be advantageous to control the pressure applied by the air bag. For young or small children, it is usually desirable to utilize less pressure in the air bag than when the vehicle occupant is an adult or larger sized individual.
Inflation systems have been proposed that are intended to take into consideration such factors as the degree of vehicle impact, age, and/or size of the vehicle occupant and/or the position of the occupant in the vehicle. In one prior art system, multiple gas generating units for filling an air bag with gas can be selectively activated. More than one such unit is activated when it is desirable to provide relatively increased pressure in the air bag. In another known prior art system, an electrically controlled vent valve, together with two igniters, are used. The vent valve provides a pathway for gases different from the pathway to inflate the air bag. Based on this configuration, if the electronic controller maintains the vent valve closed and fires each of the two igniters, the air bag inflates with 100% of the gas that is generated. On the other hand, for example, if the vent valve is controlled open and only one of the two igniters is fired, the air bag is inflated with a fraction of the maximum possible gas that could be provided.
Although inflator systems have been previously advanced related to controlling the inflation of an air bag, it would be beneficial to incorporate a relatively less complex arrangement that satisfies the key requirements associated with controlling the inflation of an air bag, including relying on components that are already available or are used in such a system, making as few modifications as is necessary to the air bag module and keeping the addition of parts thereto as few as possible.
SUMMARY OF THE INVENTION
In accordance with the present invention, a multiple initiator inflator is disclosed for use in a vehicle. In one embodiment, a dual initiator inflator is provided in which each of the two initiators is selectively activated in a predetermined way, depending upon whether the vehicle in which the inflator is located is subject to a low impact collision, a high impact collision, or an impact collision between low and high impacts (intermediate impact collision). The inflator can be configured for positioning in the vehicle at any one of a number of vehicle locations. In one embodiment, the inflator is a passenger inflator positioned to inflate an air bag or inflatable that engages the front of the passenger. In another embodiment, the inflator is a driver inflator positioned to inflate an air bag that engages the front of the driver of the vehicle.
The passenger inflator includes an inflator housing for storing a pressurized medium. The pressurized medium or stored gas can include one or more gases and is preferably comprised of oxygen and an inert gas. The inflator housing has first and second ends that are disposed at opposing ends of the length of the inflator housing. At the first end, a first initiator assembly including a first initiator is joined to the inflator housing. A first gas generating assembly is located adjacent to the first initiator assembly. The first gas generating assembly includes a first propellant. When ignited, the first propellant generates products of combustion including propellant gases that, together with the stored gas, are used to fill or pressurize the inflatable. That is, the inflation gases, which are a combination of the products of combustion generated by the ignition of the first propellant and the stored gas, flow to the inflatable and fill it. In that regard, the inflator also includes an outlet assembly through which inflation gases pass into the inflatable. In one embodiment, the outlet assembly is located adjacent to the first initiator assembly and includes a diffuser from which inflation gases are received by the inflatable of the inflatable or air bag module. In this embodiment, the outlet assembly includes a projectile and a closure member or disk. When the inflator is activated and the first initiator is fired, the projectile is caused to move through the closure member thereby rupturing or opening it in order to permit the flow of inflation gases to the diffuser. The first gas generating assembly also has an outlet member having a number of radially spaced holes from which products of combustion including inflation gases generated by ignition of the first propellant are able to escape. Such propellant gases mix with the stored gas and are able to exit the inflator housing after rupturing of the closure member.
At the second or opposite end from the first end, the passenger inflator includes a second initiator assembly comprising a second initiator that is controllably activated, depending upon the occurrence of a low impact, high impact, or other impact (e.g. intermediate) vehicle collision. A second gas generating assembly including a second propellant are disposed adjacent the second initiator assembly. When the second initiator is fired, the second propellant generates products of combustion. Such products of combustion are able to exit the gas generating assembly through an outlet end thereof. This outlet end permits the escape of products of combustion in a direction generally parallel to the length of the inflator housing.
When a high impact collision is detected, both first and second initiators are preferably activated simultaneously or substantially simultaneously (no greater than about 5 msec between their activations). In such a case, propellant gases for pressurizing the air bag are produced by both the first and second propellants, with propellant gases due to the combustion of the first propellant being about 70% of the total propellant gases, and with the propellant gases associated with combustion of the second propellant being the remainder, about 30%. Such propellant gases are combined with the stored gas for exiting the inflator.
When a low impact collision is detected, a control or trigger signal is generated and applied to the first initiator. Upon activation thereof, the first propellant is ignited and inflation gases are subsequently received by the inflatable, which inflation gases are due to the combination of the stored gas and products of combustion from the ignition of the first propellant. The second propellant is not ignited for use in augmenting the inflation gases used to fill the air bag during a low impact event. However, to eliminate the presence of a live or ignitable propellant and/or initiator after activation of the inflator, another control signal is applied to the second
Butt Ron J.
Hamilton Brian K.
Parks Brent A.
Pierce Stanley W.
Struckman David W.
Autoliv ASP Inc.
English Peter C.
Sheridan & Ross P.C.
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