Tubular dual stage inflator
A tubular inflator has a bulkhead that divides the inflator into a first and second combustion chambers. Each combustion chamber has an igniter assembly, gas generant, and compressed wire filter. The wire filters in the inflator are positioned so that they contact the bulkhead. The filters and the bulkhead prevent sympathetic ignition in the inflator, which is defined as the ignition of gas generant in one combustion chamber from the heat generated from the burning of the gas generant in the other combustion chamber. The igniter assembly has an igniter core that is molded by a unitary plastic material. The plastic overmold has threads for attaching the igniter assembly to the inflator, and the plastic overmold has a retainer portion for retaining an enhancer tablet.
1. An inflator comprising:
a housing having a bulkhead dividing the housing into a first combustion chamber and a second combustion chamber, wherein the housing has a first plurality of exit ports arranged around a circumference of the housing for providing a first pathway for inflation gas to exit the inflator from the first combustion chamber and a second plurality of exit ports arranged around the circumference of the housing for providing a second pathway for inflation gas to exit the inflator from the second combustion chamber;
a first endcap having an opening for receiving a first igniter assembly, wherein the first endcap is fastened to a first end of the housing, and a second endcap having a center opening for receiving a second igniter assembly, wherein the second endcap is fastened to a second end of the housing;
a first filter having essentially a circular shape disposed in the first combustion chamber adjacent to the bulkhead such that the first filter is interposed between said first plurality of exit ports and a gas generant disposed in the first combustion chamber, the first filter having a width that is less than half of a length of the housing for the first combustion chamber;
a second filter having essentially a circular shape disposed in the first combustion chamber adjacent to the bulkhead such that the second filter is interposed between said second plurality of exit ports and a gas generant disposed in the first combustion chamber, the second filter having a width that is less than half of a lenath of the housing for the second combustion chamber; and
wherein each igniter assembly comprises an igniter core having electrodes for carrying an electrical signal to a bridge wire, wherein the passage of current along the bridge wire creates sufficient heat to ignite an ignition material, a plastic overmold partially surrounding the igniter core having threads for attachment to the inflator in a manner to prevent moisture incursion, wherein the plastic overmold has a retainer portion defining a cavity for receiving an enhancer tablet, and the enhancer tablet adiacent to the ignition material and to the gas generant, wherein ignition of the ignition material lights the enhancer tablet, which in turn lights the gas generant.
2. The inflator according to claim 1 wherein the exit ports for the first combustion chamber are arranged in a row situated equal distance from an end of the housing, and the exit ports for the second combustion chamber are arranged in a row situated equal distance from an end of the housing.
3. The inflator according to claim 1 wherein the first filter has a diameter smaller than the diameter of an interior surface of the first combustion chamber whereby a ring shaped gap exists between the housing and the first filter, the second filter has a diameter smaller than the diameter of an interior surface of the second combustion chamber whereby a ring shaped gap exists between the housing and the second filter.
4. The inflator according to claim 3 further comprising a first position ring and a second position ring, the first position ring disposed on a side of the first filter facing the first endcap, the second position ring disposed on a side of the second filter facing the second endcap, wherein the first position ring prevents inflation gas from exiting the first combustion chamber of the inflator without flowing through the first filter, wherein the second position ring prevents inflation gas from exiting the second combustion chamber of the inflator without flowing through the second filter.
5. The inflator according to claim 1 wherein the retainer portion of each igniter assembly has vertical slots forming a plurality of concave flexible walls, the concave walls flex for facilitating the loading and securing of the enhancer tablet in the igniter assembly.
6. An inflator comprising:
a gas generant for producing inflation gas to inflate an airbag; and an igniter assembly comprising;
an igniter core having electrodes for carrying an electrical signal to a bridge wire, wherein the passage of current along the bridge wire creates sufficient heat to ignite an ignition material,
a plastic overmold for partially surrounding the igniter core having threads for attachment to the inflator in a manner to prevent moisture incursion, wherein the plastic overmold has a retainer portion defining a cavity for receiving an enhancer tablet, and
the enhancer tablet adjacent to the ignition material and to the gas generant, wherein ignition of the ignition material lights the enhancer tablet, which in turn lights the gas generant.
7. The inflator according to claim 6 , wherein the retainer portion has vertical slots creating a plurality of concave walls, wherein the concave walls flex for facilitating the loading and securing of the enhancer tablet in the igniter assembly.
8. The inflator according to claim 6 , wherein the plastic overmold is made from a single thermoplastic material.
9. The inflator according to claim 6 , wherein the plastic overmold covers only a portion of the electrodes.