Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-07-13
2001-01-09
English, Peter C. (Department: 3619)
Land vehicles
Wheeled
Attachment
C280S741000
Reexamination Certificate
active
06170868
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the field of inflatable safety systems and, more particularly, to a hybrid inflator.
BACKGROUND OF THE INVENTION
The evolution of inflators for automotive inflatable safety systems has resulted in the development of pressurized gas-only inflators, propellant-only inflators, and hybrid inflators. There are of course many design considerations for each of the above-noted types of inflators. In all three systems, two primary design considerations are that the air/safety bag must be expanded a predetermined amount in a predetermined amount of time in order to be operationally effective. As such, substantial development efforts have been directed to how the flow path is established between the inflator and the air/safety bag and how the subsequent flow is provided to the air/safety bag such that the above-identified objectives can be met. In hybrid inflators, which again require both a release of a stored, pressurized gas and an ignition of a gas and/or heat-generating propellant, the manner of establishing the flow path to the air/safety bag and the manner of igniting the propellant must both be addressed in a way which meets the above-noted objectives.
Another increasingly important objective is the manner in which the inflator is assembled. Complex hardware designs commonly require complex assembly procedures which increases the overall cost of the inflator. It is also, of course, important during assembly to not adversely affect the performance characteristics of the inflator and to provide an assembly procedure which is reasonable safe.
SUMMARY OF THE INVENTION
A first aspect of the present invention relates to a hybrid inflator for an inflatable safety system which utilizes a dual function initiator of sorts. The hybrid inflator has an inflator housing which stores an appropriate pressurized medium (e.g., fluid and/or gas) and a gas generator which stores an appropriate gas/heat-generating material or propellant for augmenting the flow to the air/safety bag of the inflatable safety system. A first closure disk initially isolates the hybrid inflator from this air/safety bag. An activation assembly is provided which includes at least one combustible material which is ignited when activation of the system is desired/required. Combustion products from the activation assembly are provided into direct contact with the propellant to ignite the same. These same combustion products from the activation assembly also propel a projectile through the first closure disk to initiate the flow from the inflator to the air/safety bag.
In one embodiment of this first aspect, the projectile provides a function in addition to rupturing the first closure disk to initiate the flow to the air/safety bag. For instance, the projectile may be disposed within end of the gas generator and at least partially aligned with the first closure disk. By selecting an appropriate configuration for the projectile and/or its interrelationship with the end of the gas generator through which it passes to rupture the first closure disk, the projectile may also be used to seal this end of the gas generator. This may be desirable to force the propellant gases and/or other combustion products from the activation assembly to flow from the gas generator and into the stored gas housing before exiting the inflator through the ruptured first closure disk. When a propellant is used which generates combustible propellant gases, this reduces the potential for these propellant gases combusting within the air/safety bag.
In another embodiment of this first aspect, a transfer tube is disposed internally of and spaced from the gas generator housing. All of the propellant is disposed in the space between the gas generator housing and the transfer tube, and the transfer tube includes a plurality of ports. The output from the activation assembly is directed into the interior of the transfer tube and then out through its ports to ignite the propellant. This reduces the potential for the initiation of the activation assembly adversely impacting the structural integrity of the propellant. The transfer tube may also be used to direct the output from the activation assembly to the above-noted projectile to propel the same through the first closure disk.
A second aspect of the present invention relates to a hybrid inflator which has an intermediately disposed outlet closure disk. An inflator housing has first and second ends which are separated by a first distance, and an appropriate pressurized medium is contained within this inflator housing. The inflator further includes a gas generator which contains a gas/heat-generating material or a propellant, as well as an outlet passage which is fluidly interconnectable with at least one of the inflator housing and said gas generator housing. A first closure disk is disposed within this outlet passage and is the barrier between the output from the inflator and the air/safety bag of the inflatable safety system. This first closure disk is disposed at least about 40% of the first distance (the length of the inflator) from each of the two ends of the inflator housing. The various features discussed above in relation to the first aspect of the invention may be used with this second aspect of the invention as well.
A third aspect of the present invention generally relates to a multiple chambered hybrid inflator. The inflator includes a first housing and a second housing assembly. The second housing assembly is interconnected with the first housing and is disposed interiorly thereof (e.g., concentrically disposed). The second housing assembly includes a first chamber in which an appropriate gas/heat-generating material or propellant is disposed. A second chamber is defined by the space between the first housing and the second housing assembly and contains an appropriate pressurized medium in the static state or prior to activation of the inflator. The second chamber is in constant fluid communication with the first chamber such that the first chamber also contains pressurized medium.
The second housing assembly of this third aspect also includes a third chamber. A first closure disk is associated with the third chamber and provides the initial isolation between the air/safety bag and the inflator. The third chamber is fluidly interconnectable with the second chamber, but is substantially isolated from the first chamber. As such, upon ignition of the propellant within the first chamber, propellant gases flow from the first chamber into the second chamber, and then into the third chamber. After the first closure disk is ruptured, the flow is established from the inflator to the air/safety bag.
In one embodiment of this third aspect, the above-noted dual function projectile from the first aspect may be used as the mechanism for isolating the first chamber from the third chamber. All other features discussed above in relation to the first and second aspects of the invention may be used with this third aspect as well.
In another embodiment of this third aspect, the second housing assembly includes a central housing having a sidewall and two open ends. The inflator activation assembly is disposed within and closes one of the open ends of the central housing and is appropriately secured thereto (e.g., via welding). A partition is disposed within the interior of the central housing (e.g., via a press-fit) to define the first chamber of the second housing assembly together with the activation assembly. A diffuser assembly is disposed within and closes the other open end of the central housing and is appropriately secured thereto (e.g., via welding) to define the third chamber of the second housing assembly together with the diffuser assembly. The partition, due to its interface with the central housing and the lack of any ports in the partition, substantially limits fluid any substantial flow from the first chamber directly into the third chamber. Moreover, by press-fitting the partition into the central housing, this also allows the propellant to
Baglini James L.
Butt Ron J.
Grages Dean W.
Hamilton Brian K.
Parks Brent A.
Autoliv ASP Inc.
English Peter C.
Sheridan & Ross P.C.
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