The field of this invention generally relates to pyrotechnic initiators, and more particularly to an integral pyrotechnic initiator with control circuitry enclosed in a molded connector body.
Pyrotechnic initiators have many uses in industrial and consumer applications. One important use is the inflation of airbags in motor vehicles. A pyrotechnic initiator is placed in an airbag module. When ignited, the pyrotechnic initiator releases gas and heat that activates a gas generator (inflator), ruptures a sealed gas unit, or performs some other work that inflates the airbag. The pyrotechnic initiator is typically tightly secured to the inflator by one of a number of well-known attachment strategies. The pyrotechnic initiator is also electrically attached to control circuitry by a connector. As the number of initiators per automobile, enhanced control features, and low-energy firing features have all increased, initiators often referred to as “smart initiators” or “smart low energy initiators” (“SLEI”) have been developed.
These smart initiators require control circuitry, such as a printed circuit board assembly (PCB), with active and passive electronic components. Such electronics require additional space inside the initiator, tending to increase the overall size of the initiator. Conventionally, the electronics have been incorporated between the ignition element and the gas seal area, with a PCB soldered to the output pins and the ignition element, encapsulated, and injection molded with nylon.
There are two main disadvantages to the existing design. First, the final assembly is larger than acceptable (especially for the driver's side) and requires re-qualification of the inflators. Also any future growth of the electronics may require re-qualification of the inflator. The second disadvantage is that the electronics are placed inside the gas seal area and exposed to high stresses during installation, operation, and deployment. These conditions compromise long term reliability.