Dual level inflator

Abstract

A dual level inflator is provided for creating at least two different rates and levels of air bag inflation while optimizing cost effectiveness, size, safety and performance. The dual level inflator includes a unitized gas generator canister assembly including two canisters of gas generant material connected to a common base and positioned in a chamber formed in an inflator outer housing. The unitized assembly is easily transportable and mountable on the outer housing. Each canister of the unitized assembly includes apertures permitting direct communication between each canister cavity and the chamber of the outer housing. As a result, generant material positioned in each canister is directly exposed to the conditions in the outer housing chamber. The present assembly is advantageous in that it maximizes the internal volume available to the stored gas and, after the ignition of one canister and the inflation of the air bag, the remaining canister may be ignited without reinflating the air bag due to the previous depressurization of the chamber in combination with the selection of a generant material incapable of effectively burning in a low pressure environment, i.e. the directly connected chamber. The present dual inflator also includes seal means to prevent inadvertent ignition, and an arrangement by which the plurality of apertures formed in one canister are positioned relative to the apertures in the other canister to cause the gas flowing from one set of apertures to be sufficiently cooled by the inert gas in the chamber prior to reaching the apertures of the other canister thereby preventing inadvertent thermally induced ignition of the generant material in the remaining unfired canister.