Cold Gas Airbag Inflation System
The Microsys cold gas airbag inflation system is used to inflate airbags using compressed gas. Powered by patent pending Microsys ultra fast high-throughput valve, the new Cold Gas System can generate pressure curves that replicate airbag inflator performance, from extremely fast inflators used with side and curtain airbags to high-volume inflators designed for passenger-side airbags. Pyrotechnic, hybrid and compressed gas inflators can be replaced with the Cold Gas System.
Both single-stage and even dual-stage inflators curves can be generated, using a Microsys proprietary electronic firing valve that fully opens within 2 msec of the trigger pulse. The Microsys Cold Gas System allows adjustments in gas quantity from 0.5 to 8 moles, and has a speed adjustment to cover the full range of known airbag inflators.
There are several primary applications for the Microsys Cold Gas System:
Airbag module research & development
Airbag cushion fold experimentation
Cushion & fabric development
Research & development of seamless instrument panels, covers, seats
Inexpensive production testing or airbag related products
Usage Example #1: Airbag Module Development
Replacing inflators in the airbag module development process results in a faster schedule and large cost savings by eliminating the majority of prototype inflators used for design testing. Also, with the 1% repeatability of the new Microsys Cold Gas System, airbag engineers are able to quickly ascertain the effect of design changes.
In use, the Cold Gas System is connected to an airbag and the airbag deployed. System settings are adjusted until the airbag deployment performance is satisfactory. Then the Cold Gas System is connected to a test tank and the pressure curve from that test becomes the specifications for the airbag inflator.
Usage Example #2: Instrument Panel (IP) or Airbag Cushion R&D
For interiors companies developing seamless instrument panels or seats, or for cushion designers, the Microsys Cold Gas System can replace inflators for most R&D testing. This allows engineers to easily adjust the airbag speed and pressure to determine the effect on their product, which is impossible to do using live inflators. Compared to using inflators the Microsys Cold Gas System offers more than better product designs; it is also far more repeatable, allows for faster cycle times, and saves the cost of expensive live airbags. Usage is similar to example #1 above.
Usage Example #3: To replace an inflator for Production Testing
In this mode the Microsys Cold Gas System is an inexpensive, adjustable and repeatable substitute for an actual inflator. Prior to use the System performance must be calibrated by connecting the output to a test tank, typically either 60L or 28.3L. The Cold Gas System settings would be adjusted until the test tank pressure curve is equivalent to the pressure curve of the inflator it is replacing. At this point the Cold Gas System may be connected to an airbag for deployment.
Cold Gas Inflation System Performance
he Microsys Cold Gas Inflation System has several adjustable settings that determine system performance:
Charge tank pressure
Charge tank volume
Gas type: helium, helium/argon mix, nitrogen
The charge tank pressure and volume determine the gas quantity in moles, which in conjunction with the volume of the test tank will determine the maximum steady-state pressure within the discharge tank. Most cold gas inflators have between 1 mol and 8 mol of gas with the smallest sizes used for side airbags and curtain airbags, and the larger sizes used for driver and passenger airbags.
The cold gas system contains a adjustable orifice downstream from the valve whose function is to decrease the rise time. The maximum diameter of this orifice is 20mm. Reducing the orifice diameter constricts the gas flow and slows the pressure rise time.
The gas type also influences the pressure rise time. Lighter gases such as helium flow very quickly resulting in faster rise times than heavier gases such as argon or nitrogen. For applications in which a close approximation of an inflators’ pressure curve is required, a Helium or a Helium/Argon mix may be the best choice. If the volume of tests is very high and the consumables cost is a factor, Nitrogen is a possible choice if it’s performance is acceptable.
By using a specific combination of Helium and Nitrogen it's possible to reproduce the leakage effect of a hot gas pyro inflator, as well as the jetting effect.
The rise time of the pressure curve is determined by the combination of orifice diameter and the gas type.
The Microsys cold gas airbag inflator can be manual controlled, or for optimum performance, controlled by SureFire. SureFire will measure the airbag pressures, control high-speed video equipment, monitor all safety hardware and ensure that test data is safely and efficiently captured and recorded.
The Microsys Cold Gas System comes in two electronic firing variations: single-stage and dual stage. As well, an inexpensive single stage pneumatic firing version is available which is perfect for interiors companies that want to replace inflators for Conformance of Production (COP) testing of IPs and seats.