Land vehicles – Wheeled – Attachment
Utility Patent
1998-12-01
2001-01-02
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S741000
Utility Patent
active
06168200
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an inflator device including gas generators and more specifically to a dual level inflator which can selectively release gas at different rates and levels and thus enable an air bag or the like type of inflatable safety restraining device, to be deployed at different output levels in accordance with different sensor inputs.
2. Description of the Related Art
Recently, there has been a demand for controlling the rate and amount of inflation of safety devices such as air-bag restraint systems, in accordance with variables such as passenger size, position, seat belt usage and the velocity of the vehicle at time of collision.
In order to provide optimal occupant protection, different levels of output are required from the air bag inflator. For example, in a high speed collision with a large unbelted person, fill rapid inflation of the air bag is required to provide the best restraint. In lower speed crashes with smaller size occupants or even out-of-position occupants, a lower, slower rate of inflation is required so as not to inadvertedly injure the occupant but still provide enough inflation to provide restraint.
In order to achieve the two levels of inflation, it has been proposed in U.S. Pat. No. 3,773,353 to Trowbridge et al. to provide two separate charges and to ignite one in the event that a slow inflation is required and to ignite both in the event of a high speed collision, thus achieving the very rapid inflation and deployment of the air bag which is necessary under such circumstances. In this device the charges are arranged within a reservoir which is filled with a non-toxic gas under pressure. This housing is sealed by a burst plate that is punched out by a piston and rod type of arrangement when a first of the two charges is detonated. This arrangement however, suffers from the drawback of being relatively complex and therefore, relatively expensive. For example, no less than three burst plate arrangements are necessary. Also, the charges are each isolated from the reservoir and reservoir gas by an inner housing and a respective rupturable closure.
U.S. Pat. No. 3,905,515 to Allemann discloses another two-stage inflator assembly which utilizes two separate charges and which disposes the charge in a chamber which is used to store a non-noxious gas under pressure. However, this arrangement is even more complex than that in U.S. Pat. No. 3,773,353. In this arrangement a portion of the burst disc forms the head of a slidable shuttle valve member which is projectable into an exhaust passage to partially throttle the outflow of gases following a detonation of one or both of the two charges.
Another important concern in dual level inflator design is the disposability of the inflator assembly after use when, for example, the inflator assembly may be removed for disposal or the entire vehicle junked. In dual level devices, if one gas generator has been ignited, for example in reaction to a low speed collision, the other generator could remain ignitable, thereby posing a potential safety concern perhaps during removal or vehicle storage. If accidentally ignited, the second generator could produce hot high pressure gasses.
For this reason, it is preferred in the event of a scenario where only the first generator is deployed, the second generator also be deployed after the immediate impact but still within the crash event, e.g., up to 100 milliseconds after impact. In this case, it is important to provide as little output into the air bag as possible so that the bag will not reinflate and impact the occupant.
European Patent Publication No. 800965 to Buchanan discloses an inflator including a spherical housing forming a main chamber and two heating devices mounted in the main chamber. The heating devices are activated sequentially to achieve a wide range of performance. However, each heating device is covered with a barrier shell to isolate the device from the gas in the main chamber. As a result, the pressure in the heating device must rise to a level sufficient to rupture the barrier shell. Also, due to the nature of the gas generant typically used in inflators, the gas generant burns more rapidly under greater pressure causing increased heating and/or gas generation. If this inflator were operated in a dual mode and only one heating device activated corresponding to a low speed impact, intentional or inadvertent ignition of the remaining gas generator may be sufficient to reinflate the air bag.
Also, the heating devices are isolated from the stored gas thus wasting volume which might be occupied by the stored gas which could make the entire inflator smaller. U.S. Pat. Nos. 5,582,428 and 5,630,619 discloses other similar inflators. However, these inflators are unnecessarily complex with multiple burst disks and multiple containers and further are also likely cause reinflation of the air bag upon later ignition of an unused generator. Moreover, the devices disclosed in Trowbridge et al. and Allemann, discussed hereinabove, suffer drawbacks similar to the device disclosed in Buchanan.
Consequently, there is a need for a cost effective, compact, simple dual level inflator capable of permitting ignition of a second generator after ignition of a first generator without reinflation of a collapsed air bag so as to deactivate the unit for disposal.
SUMMARY OF THE INVENTION
It is an object of the present invention, therefore, to overcome the disadvantages of the prior art and to provide a cost effective yet safe dual level inflation device which effectively permits dual level performance.
A further object of the present invention is to provide a dual level inflator which permits ignition of one or both generators causing initial air bag inflation and subsequent ignition of a second generator in a scenario calling for the output of only one generator, without reinflation of the air bag.
It is a further object of the present invention to provide a dual level inflator including a unitary generator canister subassembly which maximizes internal volume available for the stored gas, is easily transportable, and simply attached to the inflator assembly.
Yet another object of the present invention is to provide a dual level inflator which improves safety to personnel after a vehicle accident, by permitting deactivation of the second generator within the crash event.
Another object of the present invention is to provide a dual level inflator which permits the gas generator loads at each level to be independently adjusted depending on system requirements thereby maximizing tailorability.
Still another object of the present invention is to provide a dual level inflator which minimizes the cost and size of the assembly.
These and other objects of the present invention are achieved by providing a dual level inflation device for inflating a vehicle safety restraint, comprising an outer housing including a chamber for containing a quantity of stored inert gas and an outlet for directing pressurized gas into the vehicle safety restraint, a first generator canister mounted in the chamber and including a first canister wall forming a cavity containing gas generant material and at least one aperture to permit open communication between the cavity and the chamber, and a second generator canister mounted in the chamber and including a second canister wall forming a cavity containing gas generant material and at least one second aperture to permit open communication between the cavity and the chamber. Importantly, the gas generant material in both the first generator canister and the second generator canister is exposed to the stored inert gas to prevent an undesired pressure increase in the respective cavity upon ignition of the generant material and to maximize the internal volume available to the stored gas, thus minimizing the overall size of the inflator. The dual level inflation device also includes at least one igniter for igniting the gas generant material in the first and second generator canisters. The
DiGangi Scott Joseph
Greist, III Darton E.
Robbins Richard K.
Atlantic Research Corporation
Dickson Paul N.
Fleming Faye M.
Nixon & Vanderhye PC
Presta Frank P.
LandOfFree
Dual level inflator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dual level inflator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual level inflator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2501099