Air bag system

• US 20070055429A1
• Filed: 09/01/2006
• Published: 03/08/2007
• Est. Priority Date: 09/06/2005
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Komaki, Hiroyuki, Tani, Yasushi, Inoue, Kenichi, Kondou, Tsutomu
• Granted Patent: US 7,739,012 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60R 2021/01068 between different sensors and airbag control unit
• CPC Class Codes: B60R 2021/01184 Fault detection or diagnostic circuits in power circuits B60R2021/01129
• CPC Class Codes: B60R 2021/0119 Plausibility check
• CPC Class Codes: B60R 21/013 including means for detecting collisions, impending collisions or roll-over

Abstract

To achieve an air bag system in which a safing determination processing circuit can be implemented on one integrated circuit, the air bag system, which is equipped with first and second sensors (101, 103) for detecting a vehicle crash, and which outputs a signal for expanding an air bag when it is determined that a vehicle crash has occurred based on the outputs of the first and second sensors, comprises: a processing unit (3) for processing an output signal of the first sensor (101) by software; and a processing circuit (2) for processing an output signal of the second sensor (103) by hardware, wherein the processing unit (3) includes a non-activation fault diagnosis section (33) which, based on the output signal of the second sensor (103), detects a failure that can lead to non-activation of the air bag, and the processing circuit (2) includes an erroneous-activation fault diagnosis section (240) which, based on the output signal of the second sensor (103), detects a failure that can lead to erroneous activation of the air bag.

Claims

1. An air bag system which is equipped with first and second sensors for detecting a vehicle crash, and which outputs a signal for expanding an air bag when it is determined that a vehicle crash has occurred based on outputs of said first and second sensors, said air bag system comprising:

a processing unit for processing an output signal of said first sensor by software; and

a processing circuit for processing an output signal of said second sensor by hardware, wherein

said processing unit includes a non-activation fault diagnosis section which, based on the output signal of said second sensor, checks for the presence of a non-activation fault in which, in a situation where said air bag is to be expanded, said second sensor outputs a signal that is contradictory to said situation, and

said processing circuit includes an erroneous-activation fault diagnosis section which, based on the output signal of said second sensor, checks for the presence of an erroneous-activation fault in which, in a situation where said air bag is not to be expanded, said second sensor outputs a signal that is contradictory to said situation.

2. An air bag system as claimed in claim 1, wherein said first sensor is a first acceleration sensor, and said second sensor is a second acceleration sensor for safing purposes, and wherein

said processing unit is constructed from one microcomputer which includes, in addition to said non-activation fault diagnosis section, a crash determination section for making a crash determination by processing the output signal of said first acceleration sensor and a fault diagnosis section for diagnosing operation faults in said acceleration sensor and said crash determination section, and

said processing circuit is constructed from one integrated circuit which includes, in addition to said erroneous-activation fault diagnosis section, a safing determination section for making a safing determination by processing the output signal of said safing second acceleration sensor.

3. An air bag system as claimed in claim 2, wherein said one integrated circuit further includes an output circuit for outputting an air bag firing signal based on a crash signal from said microcomputer and a signal from said safing determination section.

4. An air bag system as claimed in claim 3, wherein said one microcomputer further includes an output disabling section for disabling the output of said safing determination section of said one integrated circuit when a fault is detected by said non-activation fault diagnosis section.

5. An air bag system as claimed in claim 3, wherein said one microcomputer outputs a pseudo-crash signal to said second acceleration sensor, and performs said non-activation fault diagnosis based on a signal that said second acceleration sensor outputs in response to said pseudo-crash signal.

6. An air bag system as claimed in claim 5, wherein said one microcomputer outputs a signal for disabling the output of said output circuit to said output circuit in said one integrated circuit at the same time that said pseudo-crash signal is output to said second acceleration sensor.

7. An air bag system as claimed in claim 5, wherein said one microcomputer includes a monitoring section for monitoring the output of said second acceleration sensor, and performs said non-activation fault diagnosis based on a result of said monitoring.

8. An air bag system as claimed in claim 7, wherein said one microcomputer includes a first A/D converter for A/D converting the output of said first acceleration sensor, and said one integrated circuit includes a second A/D converter for A/D converting the output of said second acceleration sensor, and wherein said monitoring in said one microcomputer is performed using said first A/D converter.

9. An air bag system as claimed in claim 8, wherein said non-activation fault diagnosis section of said one microcomputer is equipped with a function for monitoring the output of said second A/D converter of said one integrated circuit.

10. An air bag system as claimed in claim 2, wherein said safing determination section includes a plurality of safing determination equations, an appropriate one of which is externally selectable, and a plurality of threshold values, an appropriate one of which is externally selectable.

11. An air bag system as claimed in claim 10, wherein said plurality of safing determination equations and said plurality of threshold values can be selected by adjusting an externally applied voltage.

12. An air bag system as claimed in claim 10, wherein selection from among said safing determination equations and said threshold values is made based on the type of vehicle in which said air bag system is mounted.

13. An air bag system as claimed in claim 6, wherein said one microcomputer includes a monitoring section for monitoring the output of said second acceleration sensor, and performs said non-activation fault diagnosis based on a result of said monitoring.

14. An air bag system as claimed in claim 11, wherein selection from among said safing determination equations and said threshold values is made based on the type of vehicle in which said air bag system is mounted.