Airbag system having multiple collision determining circuits

• US 7,434,835 B2
• Filed: 08/17/2006
• Issued: 10/14/2008
• Est. Priority Date: 03/20/2003
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Shimizu, Nobuyoshi
• Primary Examiner(s): Ilan; Ruth
• Application Number:
  US11/505,311
• Publication Number:
  US 20060273560A1
• Time in Patent Office: 789 Days
• Field of Search: 280/735, 701/45, 307/10.1, 180/282, 180/274
• US Class Current: 280/735
• CPC Class Codes: B60R 21/0132 responsive to vehicle motion parameters , e.g. to vehicle longitudinal or transversal deceleration or speed value
• CPC Class Codes: B60R 21/017 including arrangements for providing electric power to safety arrangements or their actuating means, e.g. to pyrotechnic fuses or electro-mechanic valves

Abstract

An airbag system comprises an airbag, an inflator, a squib, a high-side switch, a low-side switch, a firing circuit for switching the two switches, a first motion detecting circuit including an acceleration sensor, a second motion detecting circuit including an acceleration sensor, a first collision determining circuit for outputting a firing signal to the firing circuit, and a second collision determining circuit for outputting a firing signal to the firing circuit. The first collision determining circuit comprises an analog comparator for comparing a signal from the first motion detecting circuit with a reference value.

Claims

1. An airbag system for a car, comprising:

an airbag inflatable with gas;

an inflator for producing gas for the airbag;

a squib for firing the inflator;

a firing circuit including a high-side switch and a low-side switch for allowing a firing current to flow or preventing the current from flowing through the squib, on the high-voltage and low-voltage sides, respectively, of the squib;

the firing circuit further including a switch driving means for switching the two switches independently or together;

a first motion detecting circuit including a first motion sensor for outputting an electric signal representing the motion of the car;

a second motion detecting circuit including a second motion sensor for outputting an electric signal representing the motion of the car;

a first collision determining circuit; and

a second collision determining circuit independent of the first collision determining circuit;

the first and second collision determining circuits being adapted to determine on the basis of the electric signals from the first and second motion detecting circuits, respectively, whether the car has collided or not;

the two collision determining circuits being further adapted to output firing signals to the switch driving means of the firing circuit when the car collides,

wherein the airbag is inflated when the car collides,

the first collision determining circuit comprising an A/D converting means for converting an analog signal received from the first motion detecting circuit into a digital signal, a determination operating means for determining on the basis of the digital signal whether the car has collided or not, and a signal outputting means for outputting a firing signal to the switch driving means of the firing circuit in response to a collision signal output from the determination operating means when the car collides, the A/D converting means, the determination operating means and the signal outputting means being combined with the firing circuit, and

wherein the A/D converting means, the determination operating means and the signal outputting means of the first collision determining circuit, and the switch driving means of the firing circuit are incorporated into a driving IC.