초록 ▼

An inflator for an airbag system has a target mounted in the pressurized gas contained in the inflator. An ultrasonic transducer is mounted on an external surface of the inflator in alignment with the target. The transducer generates and receives reflected ultrasonic signals from the target. The tim

An inflator for an airbag system has a target mounted in the pressurized gas contained in the inflator. An ultrasonic transducer is mounted on an external surface of the inflator in alignment with the target. The transducer generates and receives reflected ultrasonic signals from the target. The time-of-flight of the signals which are dependent on the gas pressure are used to determine the gas pressure in the inflator. Temperature compensation is provided by fabricating the target of bimetallic material which changes the spacing of the target from the transducer with temperature or providing a temperature sensitive element, e.g. a thermocouple to electrically provide temperature compensation.

대표청구항 ▼

[ We claim:] [1.] An ultrasonic gas pressure measurement system for measuring gas pressure in an inflator of a vehicle airbag module comprising:an inflator containing pressurized gas which, on the activation of said inflator, is adapted to be released into an airbag stored in an airbag module for in

[ We claim:] [1.] An ultrasonic gas pressure measurement system for measuring gas pressure in an inflator of a vehicle airbag module comprising:an inflator containing pressurized gas which, on the activation of said inflator, is adapted to be released into an airbag stored in an airbag module for inflating the airbag, said inflator having a target surface therein,a temperature compensation means mounted in said inflator for compensating for any changes in gas pressure due to temperature,an ultrasonic transducer means mounted on said inflator in alignment with said target surface for transmitting ultrasonic signals to said target surface and detecting reflected ultrasonic signals from said target surface,wherein said temperature compensation means comprises a bimetallic member which forms said target surface in said inflator whereby changes in temperature of said pressurized gas in said inflator changes the distance between said target surface and said ultrasonic transducer means, thereby varying the time-of-flight of said ultrasonic signals in said inflator in accordance with temperature to compensate for changes in temperature,whereby time-of-flight of the ultrasonic signals to and from the target through the pressurized gas in the inflator is used to determine the gas pressure in the inflator taking into account the temperature of the pressurized gas.