Hybrid inflator

Details Hybrid inflator Hybrid inflator

2000-10-06

2002-12-03

Dickson, Paul N. (Department: 3616)

Land vehicles

Wheeled

Attachment

C280S740000

Reexamination Certificate

active

06488310

ABSTRACT:

TECHNICAL FIELD TO WHICH THE INVENTION BELONGS
The present invention relates to an inflating-type safety system for a motor vehicle, more specifically to a hybrid inflator capable of inflating an air bag reliably and rapidly, and to an air bag system using the hybrid inflator.
1. Prior Art
With the development of an inflator for an inflating-type safety system of motor vehicles, a hybrid inflator using both a pressurized gas and a solid gas generating agent has been attracting attention. A main design requirement for a hybrid inflator is that the inflator inflates an air bag to a predetermined amount in a predetermined time so that the air bag is effectively activated. Various proposals concerning a structure to meet the requirement have heretofore been made (for example, as referred in JP-A 8-2824 27). Since such a hybrid inflator is manufactured to be installed in a motor vehicle, the weight and dimensions of the inflator, which have influence upon the weight of the motor vehicle, constitute an important design requirement therefor. And it is required to reduce the weight and number of parts while maintaining function as the hybrid inflator.
2. Disclosure of the Invention
An object of the present invention is to provide a hybrid inflator in which a weight of the inflator can be reduced and manufacturing process can be simplified, and to provide an air bag system using such a hybrid inflator.
A hybrid inflator of the present invention can be applied to any of a single type hybrid inflator having a single gas generating chamber and a multistage inflating hybrid inflator having two (dual type) or more than three gas generating chambers.
The present invention provides, as one means for solving the above problem, a hybrid inflator for an inflating-type safety system of a vehicle provided with an air bag, which comprises an inflator housing, a gas generator provided in the inflator housing, and an ignition means chamber having an ignition means joined to the gas generator, wherein
the interior of the inflator housing is filled with a pressurized medium containing an inert gas,
the gas generator has an outer shell formed by a gas generator housing having a plurality of communication holes, the gas generator includes, in the gas generator housing, a gas generating chamber which accommodates a gas generating agent, the gas generating chamber and the inflator housing are in communication with each other through the communication holes,
each of the communication holes provided in the gas generator housing has such a size that combustion gas generate in the gas generating chamber can flow out therethrough but the gas generating agent can be prevented from leaking outside.
This hybrid inflator is of a single type having one gas generating chamber. It is possible to prevent the gas generating agent from leaking outside without using a leak-blocking screen by adjusting a size (hole diameter) of the plurality of the communication holes. Since the screen for covering the communication holes by which the inflator housing communicates with the gas generating chamber provided in the gas generator housing is not used, a weight of the hybrid inflator can be reduced by a weight of the screen. Further, since a mounting step of the screen is unnecessary, the number of manufacturing steps can be reduced, and the manufacturing step can be simplified.
Further, as another means for solving the above problem, the present invention provides a hybrid inflator for an inflating-type safety system for a vehicle provided with an air bag, which comprises an inflator housing, a gas generator provided in the inflator housing, and an ignition means chamber having ignition means connected to the gas generator, wherein
the gas generating agent can be prevented from leaking outside. pressurized medium containing an inert gas,
the gas generator has an outer shell formed by a gas generator housing having a plurality of first and second communication holes,
the gas generator housing includes, therein, first and second gas generating chambers each having a gas generating agent, the first gas generating chamber and the inflator housing are in communication with each other through the first communication holes, the second gas generating chamber and the inflator housing are in communication with each other through the second communication holes,
each of the first and/or second communication holes has such a size that combustion gas generated in the first and/or second gas generating chamber can flow out therethrough but the gas generating agent can be prevented from leaking outside.
In the present invention, the following three modes may be employed: (a) the plurality of the first communication holes are not covered by the screen, but the plurality of the second communication holes are covered by the screen, (b) the first communication holes are covered by the screen, but the second communication holes are not covered by the screen, and (c) both the first and second communication holes are not covered by the screen. Among these embodiments, (c) is most preferable.
This hybrid inflator is of a dual-type having two gas generating chambers. Like the above-described single type hybrid inflator, it is possible to prevent the gas generating agent from leaking outside by adjusting a size (hole diameter) of the first and second communication holes without using a screen. Since the screen for covering the plurality of the communication holes by which the inflator housing communicates with the gas generating chambers provided in the gas generator housing is not used, a weight of the hybrid inflator can be reduced by a weight of the screen. Further, since a mounting step of the screen can be omitted, the number of manufacturing steps can be reduced, and thereby, the manufacturing step can be simplified. In a conventional dual-type hybrid inflator, a screen is mounted on each of the first and second communication holes. Since the screens are not used, the number of parts can be reduced by two, and since the mounting step of the two screens can be omitted, effects of reducing a weight and simplifying manufacturing steps are extremely great.
In the hybrid inflator of the present invention, the plurality of the communication holes or the plurality of the first and second communication holes provided in the gas generator housing can have the same hole diameters. By setting the hole diameters of the communication holes to the same, it becomes easy to control the amount of outflow and the outflow state of combustion gas generated by burning the gas generating agent, and additionally, manufacture of the gas generator housing can be facilitated.
In the hybrid inflator of the present invention, plurality of the communication holes or the plurality of the first and second communication holes provided in the gas generator housing may have hole diameters in a range of 0.5 to 3 mm, more preferably in a range of 1.0 to 2.0 mm. By setting the hole diameter of each of the plurality of the communication holes or the plurality of the first and second communication holes in the predetermined range, the amount of outflow and the outflow-state of a combustion gas generated by combustion of the gas generating agent can be controlled easily.
And, in the hybrid inflator of the present invention, the total number of the communication holes or the first and second communication holes provided in the gas generator housing may be 100 to 600, more preferably 200 to 500. By setting the total number of the communication holes or the first and second communication holes in a predetermined range, the amount of outflow and the outflow-state of a combustion gas generated by combustion of the gas generating agent can be controlled easily.
And, in the dual-type hybrid inflator of the present invention, the total number of the first communication holes may be 50 to 300, more preferably 100 to 250, and the total number of the second communication holes may be 50 to 300, more preferably 100 to 250. By setting the total number of the first and second communication holes in a

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