Air bag system for protection of the occupants of motor vehicles

A system for the protection of the occupants of a motor vehicle, particularly an air bag protection system, comprising:

• a plurality of firing circuits coupled between a battery supply voltage and ground, each firing circuit including a bag igniter, each bag igniter being coupled in series with a respective triggerable power switch,
• at least one retardation sensitive mechanical arming switch coupled to said power switches,
• a single energy storage capacitor coupled to each of said firing circuits for supplying initiation energy to each circuit over an upper common power stage in the event of a loss of the battery supply voltage, and
• means for limiting the current flowing through the individual triggerable power switches, and hence through the bag igniters, from the energy storage capacitor, wherein the means for limiting limits the time duration for which the power switches are actuated by using pulsed trigger signals for actuating said power switches.

An apparatus for actuating at least one safety device for protecting the occupants in a motor vehicle during a collision, comprising:

• at least one firing circuit coupled to the safety device and to a voltage supply, the firing circuit being adapted to actuate the safety device in response to the passage of current therethrough, the firing circuit including an ignition device coupled in series with a transistor, the transistor being adapted to permit the passage of current through the ignition device to actuate the safety device;
• a capacitor coupled to the firing circuit and to the voltage supply, the capacitor being adapted to supply voltage to the firing circuit upon disconnection of the voltage supply to, in turn, actuate the safety device;
• means for determining the amount of current passing through the firing circuit from the capacitor;
• and
• means for controlling the transistor as a function of the determined amount of current passing through the firing circuit from the capacitor to limit the current passing through the firing circuit from the capacitor to permit additional safety devices to be actuated by the capacitor.

An apparatus for actuating at least one safety device for protecting the occupants in a motor vehicle during a collision, comprising:

• at least one firing circuit coupled to the safety device and to a voltage supply, the firing circuit being adapted to actuate the safety device in response to the passage of current therethrough, the firing circuit including an ignition device coupled in series with a transistor, the transistor being adapted to permit the passage of current through the ignition device to actuate the safety device;
• a capacitor coupled to the firing circuit and to the voltage supply, the capacitor being adapted to supply voltage to the firing circuit upon disconnection of the voltage supply to, in turn, actuate the safety device;
• a resistor coupled in series with the transistor;
• and
• a comparator coupled to the resistor, the transistor and a reference voltage, the comparator being adapted to compare the voltage across the resistor to the reference voltage, and if the resistor voltage exceeds the reference voltage, to transmit a signal to the transistor to limit the level of current passing through the firing circuit from the capacitor to permit additional safety devices to be actuated by the capacitor.

An apparatus for actuating a plurality of safety devices for protecting the occupants of a motor vehicle during a collision, comprising:

• a plurality of firing circuits, each firing circuit being coupled to a respective safety device and to a voltage supply, each firing circuit including an ignition device coupled in series with a power switch, each power switch being adapted to permit the passage of current through the ignition device to actuate the respective safety device;
• an electric storage device coupled to each firing circuit and to the voltage supply, the storage device being adapted to supply voltage to the firing circuits upon disconnection of the voltage supply to, in turn, actuate the safety devices;
• means for determining the amount of current passing through at least one of the firing circuits from the electric storage device;
• and
• a current limiting circuit coupled to each firing circuit and adapted to control at least one of the power switches as a function of the determined amount of current for limiting the current passing through the at least one of the firing circuits from the electric storage device to permit each firing circuit and, thus, safety device to be actuated by the electric storage device.

An apparatus for actuating a plurality of safety devices for protecting the occupants of a motor vehicle during a collision, comprising:

• a plurality of firing circuits, each firing circuit being coupled to a respective safety device and to a voltage supply, each firing circuit including an ignition device coupled in series with a power switch, each power switch being adapted to permit the passage of current through the ignition device to actuate the respective safety device;
• an electric storage device coupled to each firing circuit and to the voltage supply, the storage device being adapted to supply voltage to the firing circuits upon disconnection of the voltage supply to, in turn, actuate the safety devices;
• and
• a current limiting circuit coupled to each firing circuit and adapted to limit the current passing through the firing circuits from the electric storage device to permit each firing circuit and, thus, safety device to be actuated by the electric storage device, wherein the current limiting circuit includes
• a plurality of resistors, each resistor being coupled in series with a respective power switch;
• and a plurality of comparators, each comparator being coupled to a respective resistor and power switch, and to a reference voltage, each comparator being adapted to compare the voltage across the respective resistor to the reference voltage, and if the resistor voltage exceeds the reference voltage, to transmit a signal to the respective power switch to correspondingly reduce the level of current passing therethrough.