Passenger restraint firing circuit
First Claim
1. A firing circuit for actuating a first and second vehicle passenger restraint comprisingfour parallel circuit legs connected across a battery via a first diode placed in series therewith, the cathode of said first diode being grounded to said battery;
- said first and second circuit legs each including in seriesa diodea normally-open safing sensor connected to the cathode of the diode of said circuit leg,a trigger means having an internal resistance for deploying one of said restraints, anda normally-open crash sensor,the safing sensors and crash sensors of each of said first and second circuit legs being shunted by resistors having a nominal resistance substantially greater than the internal resistance of said trigger means;
said third and fourth circuit legs each comprising in series;
a current-limiting device from the group consisting of resistors and diodes, anda capacitor;
a first bridge connecting said first circuit leg with said second circuit leg between the diodes and the safing sensors thereof, respectively, said first bridge including a current-limiting device;
a second bridge connecting said first circuit leg with said second circuit leg between the trigger means and the crash sensors thereof, respectively;
a third bridge connecting said third circuit leg between the current-limiting device and the capacitor thereof with said first circuit leg between the diode and the safing sensor thereof, said third bridge including a diode, the cathode of the diode of said third bridge facing said first circuit leg; and
a fourth bridge connecting said fourth circuit leg between the current-limiting device and the capacitor thereof with said first circuit leg between the diode and the safing sensor thereof, said fourth bridge including a diode, the cathode of the diode of said fourth bridge facing said second circuit leg.
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Accused Products
Abstract
A firing circuit for deploying a pair of air bags comprises four circuit legs connected in parallel across a voltage supply via a diode shunted with a resistor. The first and second circuit legs each comprise in series a safing sensor, a squib, and a crash sensor, with each sensor being shunted by a like resistor whose resistance is substantially greater than the nominal resistance of the squibs. The third and fourth circuit legs each preferably comprise a resistor in series with a capacitor, with the resistance of the series resistor being significantly greater than that of the resistor shunting the grounded diode. Five bridges 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.
52 Citations
21 Claims
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1. A firing circuit for actuating a first and second vehicle passenger restraint comprising
four parallel circuit legs connected across a battery via a first diode placed in series therewith, the cathode of said first diode being grounded to said battery; -
said first and second circuit legs each including in series a diode a normally-open safing sensor connected to the cathode of the diode of said circuit leg, a trigger means having an internal resistance for deploying one of said restraints, and a normally-open crash sensor, the safing sensors and crash sensors of each of said first and second circuit legs being shunted by resistors having a nominal resistance substantially greater than the internal resistance of said trigger means; said third and fourth circuit legs each comprising in series; a current-limiting device from the group consisting of resistors and diodes, and a capacitor; a first bridge connecting said first circuit leg with said second circuit leg between the diodes and the safing sensors thereof, respectively, said first bridge including a current-limiting device; a second bridge connecting said first circuit leg with said second circuit leg between the trigger means and the crash sensors thereof, respectively; a third bridge connecting said third circuit leg between the current-limiting device and the capacitor thereof with said first circuit leg between the diode and the safing sensor thereof, said third bridge including a diode, the cathode of the diode of said third bridge facing said first circuit leg; and a fourth bridge connecting said fourth circuit leg between the current-limiting device and the capacitor thereof with said first circuit leg between the diode and the safing sensor thereof, said fourth bridge including a diode, the cathode of the diode of said fourth bridge facing said second circuit leg. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a firing circuit for actuating a first and second vehicle passenger restraint comprising
a first circuit leg including in series a first normally-open safing sensor, a first trigger means having an internal resistance for actuating said first restraint, and a first normally-open crash sensor, said first safing sensor and said first crash sensor each being shunted by a first and second resistor, respectively, said first and second shunting resistors having a resistance substantially greater than the internal resistance of said first trigger means; -
a second circuit leg connected in parallel with said first circuit leg comprising in series a second normally-open safing sensor, a second trigger means for actuating said second restraint having an internal resistance substantially equal to the internal resistance of said first trigger means, and a second normally-open crash sensor, said second safing sensor and second crash sensor each being shunted by a third and fourth resistor, respectively, said third and fourth shunting resistors having a resistance substantially greater than the internal resistance of said second trigger means; a first bridge comprising first and second oppositely-biased diodes connecting a first junction on said first circuit leg between said first safing sensor and said first trigger means with a first junction on said second circuit leg between said second safing sensor and said second trigger means; a second bridge comprising third and fourth oppositely-biased diodes connecting a second junction on said first circuit leg between said first trigger means and said first crash sensor with a second junction on said second circuit leg between said second trigger means and said second crash sensor; and means for applying a voltage across said parallel circuit legs; the improvement wherein said first circuit leg further includes a fifth diode connected in series with said first safing sensor, the cathode of said fifth diode facing said first safing sensor; said second circuit leg further includes a sixth diode connected in series with said second safing sensor, the cathode of said sixth diode facing said second safing sensor; said first bridge further includes a first current-limiting means for limiting the current permitted to flow in either direction therethrough; and said means for applying a voltage across said parallel circuit legs includes a battery; and a seventh diode connected in series with said parallel circuit legs, the cathode of said fifth diode being connected to ground; and including a third circuit leg in parallel with said first and second circuit legs including a second current-limiting device from the group consisting of resistors and a diodes, and a first capacitor connected in series with said second current-limiting device; a fourth circuit leg in parallel with said first, second and third circuit legs including a third current-limiting device from the group consisting of resistors and diodes, and a second capacitor connected in series with said third current-limiting device; a third bridge connecting a first junction on said third circuit leg between said second current-limiting device and said first capacitor with a third junction on said first circuit leg between said fifth diode and said first safing sensor, said third bridge including an eighth diode, the cathode of said eighth diode facing said third junction on said first circuit leg; a fourth bridge connecting a first junction on said fourth circuit leg between said third current-limiting device and said second capacitor with a third junction on said second circuit leg between said sixth diode and said second sating sensor, said fourth bridge including a ninth diode, the cathode of said ninth diode facing said third junction on said second circuit leg. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification