FIRING CIRCUIT

• Main Authors: KEVIN E. MUSSER, CRAIG W. WHITE
• Format: Patent
• Language: English
• Published: 20.02.1992
• Edition: 5
• Subjects: CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTINGELECTRIC POWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PERFORMING OPERATIONS; PHYSICS; SYSTEMS FOR STORING ELECTRIC ENERGY; TESTING; TESTING STATIC OR DYNAMIC BALANCE OF MACHINES ORSTRUCTURES; TESTING STRUCTURES OR APPARATUS NOT OTHERWISE PROVIDED FOR; TRANSPORTING; VEHICLES IN GENERAL; VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISEPROVIDED FOR

A firing circuit for deploying a pair of air bags comprises four circuit legs (12,14,16,18) connected in parallel across a voltage supply (20) via a diode (22) shunted with a resistor. The first and second circuit legs each comprise in series a safing sensor (26), a squib (28), and a crash sensor (30), with each sensor being shunted by a like resistor (32) whose resistance is substantially greater than the nominal resistance of the squibs. The third and fourth circuit legs (16,18) each preferably comprise a resistor (34) in series with a capacitor (36), with the resistance of the series resistor being significantly greater than that of the resistor shunting the grounded diode. Bridges (36,46,52) interconnect the four circuit legs so as to provide multiple firing paths and continued circuit viability notwithstanding the presence of one or more "faults" in the instant firing circuit. The addition, for example, of voltage detecting and comparing means about the four circuit legs, diodes and/or current-limiting devices in the bridges between the circuit legs further, and means operative to draw current from a junction on the first and second circuit legs, respectively, renders the instant firing circuit fully diagnosable in situ.