Method and apparatus for testing a dual airbag passive restraint system
First Claim
1. An apparatus for testing a dual airbag passive restraint system having two firing circuits, each one of said firing circuits having a series connection of several circuit components including at least two inertia sensors connected in series with a squib across a source of electrical energy, each one of said inertia sensors having a normally open switch and an associated parallel connected resistor, said apparatus comprising:
- means for isolating at least one of the inertia sensors in at least one of the firing circuits from the other circuit components of the associated firing circuit;
means for monitoring, in said at least one firing circuit, at least one voltage value at a component connection while said at least one inertia sensor is isolated;
means for determining from the monitored voltage value a value functionally related to the resistance of at least one circuit component in said at least one firing circuit while said at least one inertia sensor is isolated;
means for comparing the determined value against predetermined limits; and
means for providing an error indication if the determined value is not within the predetermined limits.
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Accused Products
Abstract
A method and apparatus are disclosed for testing a dual airbag passive restraint system of the type having two firing circuits, each with a series connection of several circuit components including at least two inertia sensors connected in series with a squib across a source of electrical energy, each inertia sensor having a normally open switch and an associated parallel connected resistor. The apparatus comprises a series connected diode and two switching circuits for each firing circuit for isolating at least one of the inertia sensors in each of the firing circuits from other circuit components of its associated firing circuit. A microcontroller monitors at least one voltage value at a component connection while at least one inertia sensor in each firing circuit is isolated. The microcontroller determines a value functionally related to the resistance of at least one circuit component in each firing circuit while at least one inertia sensor is isolated. The microcontroller compares the determined value against predetermined limits. If the determined value is not within the predetermined limits, an error indication is provided.
44 Citations
19 Claims
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1. An apparatus for testing a dual airbag passive restraint system having two firing circuits, each one of said firing circuits having a series connection of several circuit components including at least two inertia sensors connected in series with a squib across a source of electrical energy, each one of said inertia sensors having a normally open switch and an associated parallel connected resistor, said apparatus comprising:
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means for isolating at least one of the inertia sensors in at least one of the firing circuits from the other circuit components of the associated firing circuit; means for monitoring, in said at least one firing circuit, at least one voltage value at a component connection while said at least one inertia sensor is isolated; means for determining from the monitored voltage value a value functionally related to the resistance of at least one circuit component in said at least one firing circuit while said at least one inertia sensor is isolated; means for comparing the determined value against predetermined limits; and means for providing an error indication if the determined value is not within the predetermined limits. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for testing a dual airbag passive restraint system having two firing circuits, each with a series connection of several circuit components including at least two inertia sensors connected in series with a squib across a source of electrical energy, each said inertia sensor having a normally open switch and an associated parallel connected resistor so that a first test current having a value is established through both of the parallel connected resistors associated with said at least two inertia sensors, said apparatus comprising:
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means for isolating at least one of the inertia sensors in each of the firing circuits from the other circuit components of the associated firing circuit; means for establishing a second test current through said at least one isolated inertia sensor in each said firing circuit having a different value from said first test current value; means for monitoring a voltage value developed across the parallel connected resistor associated with said at least one isolated inertia sensor when said second test current passes therethrough; means for determining a value functionally related to the resistance of said at least one isolated inertia sensor from said monitored voltage value; means for comparing the determined value against predetermined limits; and means for providing an error indication if the determined value is not with the predetermined limits. - View Dependent Claims (8, 9, 10, 11, 12)
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13. An apparatus for testing a dual airbag passive restraint system having a first firing circuit and a second firing circuit, the first firing circuit including a first safing inertia sensor having a first normally open switch inertia switch and a first safing resistor connected in parallel with the first safing inertia switch, one terminal of the first safing inertia switch connected to a source of electrical energy, a first diode having its anode connected to a second terminal of said first safing inertia switch, a first squib having one terminal connected to the cathode of the first diode, a first front inertia sensor having a first normally open front inertia switch and a first front resistor connected in parallel with the first front inertia switch, the first front inertia sensor switch connected to a second terminal of the first squib, the second terminal of said first front inertia switch being connected to electrical ground, the second firing circuit including a second safing inertia sensor having a second normally open switch and a second safing resistor connected in parallel with the second safing inertia switch, one terminal of said second safing inertia switch connected to said source of electrical energy, a second diode having its anode connected to a second terminal of said second safing inertia switch, a second squib having one terminal connected to the cathode of the second diode, a second front inertia sensor having a second front inertia switch and a second front resistor connected in parallel with said second front inertia switch, a first terminal of the second front inertia switch being connected to the second squib, the second terminal of said second front inertia switch being connected to electrical ground, the first terminal of the first front inertia switch connected to the first terminal of the second front inertia switch and the second terminal of the first and second squibs, said apparatus further comprising:
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a first switching network connected in parallel across said series connected first safing inertia switch and said first diode, said first switching network including a first actuatable solid state switch connected in series with a first test resistor having a known resistance value for, when actuated, connecting said first test resistor in parallel with the series connection of said first diode and the associated resistor of the first safing inertia switch; a second switching network connected between the connection of the first safing inertia switch and the first diode and electrical ground, said second switch network including a second actuatable solid state switch connected in series with a second test resistor having a known resistance value for, when actuated, connecting the junction between said first safing sensor and said first diode to electrical ground through said second test resistor; a third switching network connected in parallel across said series connected second safing inertia switch and said second diode, said third switching network including a third actuatable solid state switch connected in series with a third test resistor having a known resistance value for, when actuated, connected said third test resistor in parallel with the series connection of said second diode and the associated resistor of the second safing inertia switch; a fourth switching network connected between the connection of the second safing switch and the second diode and electrical ground, said fourth switching network including a fourth actuatable solid state switch connected in series with a fourth test resistor having a known resistance value for, when actuated, connecting the junction between said second safing sensor and said second diode to electrical ground through said fourth test resistor; a fifth switching network connected between said source of electrical energy and the junction of the first terminal of the first front sensor and the first terminal of the second front inertia switch, said fifth switching network including a fifth actuatable solid state switch connected in series with a fifth test resistor having a known resistance value; a sixth switching network connected between the junction of the first terminal of the first front inertia switch and the first terminal of the second front inertia switch and electrical ground, said sixth switching network including a sixth actuatable solid state switch connected in series with a sixth test resistor having a known resistance value; means for controlling said first, second, third, fourth, fifth, and sixth solid state switches so as to selectively reverse bias said first and second diode, and establish known test currents selectively though said parallel connected resistors of said first and second safing sensors and the parallel connected resistors of the first and second front sensors; means for monitoring the voltage values of the source of electrical energy and the voltage value present at selected circuit junctions; means for determining the resistance value of at least one of said inertia sensors based upon said monitored voltage values; and means to warn the vehicle operator if the determined resistance value is not within predetermined limits. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method for testing a dual airbag passive restraint system having two firing circuits, each with a series connection of several circuit components including at least two inertia sensors connected in series with a squib across a source of electrical energy, each said inertia sensor having a normally open switch and an associated parallel connected resistor, said method comprising the steps of:
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isolating at least one of the inertia sensors in each of the firing circuits from the other circuit components of the associated firing circuit; monitoring, in each said firing circuit, at least one voltage value at a component connection while at least one of said two inertia sensors in each said firing circuit is isolated; determining from the monitored voltage value a value functionally related to the resistance of at least one of said two inertia sensors in each said firing circuit while the at least one of said two inertia sensors is isolated; comparing the determined value against predetermined limits; and providing an error indication if the determined value is not within the predetermined limits.
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Specification