Method for checking the operability of safety system for vehicles

• US 5,181,011 A
• Filed: 08/31/1991
• Issued: 01/19/1993
• Est. Priority Date: 08/14/1990
• Status: Expired due to Fees

• Current Assignee: Bosch Automotive Systems Corporation (Robert Bosch GmbH)
• Original Assignee: Zexel Corporation
• Inventors: Okano, Masami
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Popvici Dov
• Application Number:
  US07/744,414
• Time in Patent Office: 507 Days
• Field of Search: 340/436, 340/438, 340/514, 280/734, 280/735, 180/282, 180/271
• US Class Current: 340/438
• 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 21/0173 Diagnostic or recording means therefor

Abstract

A method for checking the operability of a vehicular safety system which comprises an acceleration sensor for providing a pair of differential output signals, a first and second vehicle collision discriminators having a differential amplifier responsive to the pair of differential output signals, respectively, a pair of current controllers responsive to the first and second distriminators, respectively, whereby a firing current is supplied to a firing actuator through the pair of current controllers when the vehicle collision is detected. The method is characterized in that one of the differential amplifier is changed in arrangement so as to be able to respond to an in-phase input, and a test signal for making the acceleration sensor produce pair of check signals in phase is applied to the acceleration sensor. Then the operability of the safety system is checked on the basis of the potential developed at the firing actuator at that time without the activation of the actuator.

Claims

1. A method for checking operability of a vehicle safety system, which comprises a vehicle safety device;

a firing member for activating said vehicle safety device;

an acceleration sensing means for providing a pair of output signals which correspond to acceleration of a vehicle but are opposite in phase from each other;

a first discriminating means which includes a first differential amplifying means responsive to said acceleration sensing means for producing a first detection signal corresponding to the difference between the pair of output signals and discriminates occurrence of collision of the vehicle in response to the first detection signal;

a second discriminating means which includes a second differential amplifying means responsive to said acceleration sensing means for producing a second detection signal corresponding to the difference between the pair of output signals and discriminates the occurrence of collision of the vehicle in response to the second detection signal;

a first means responsive to said first discriminating means for allowing a current to flow therethrough between one terminal of said firing member and a power source when the occurrence of collision of the vehicle is discriminated by said first discriminating means; and

a second means responsive to said second discriminating means for allowing a current to flow therethrough between the other terminal of said firing member and the power source when the occurrence of collision of the vehicle is discriminated by said second discriminating means;

whereby a firing current is allowed to flow through said firing member from the power source when both said first and second means are rendered operative at the same time, said method comprising the steps of;

causing said acceleration sensing means to produce a pair of check signals which are identical;

making a circuit change in one of said first and second differential amplifying means to enable it to respond to an in-phase input;

detecting whether or not a potential difference is developed across said firing member in response to application of the check signals to said first and second differential amplifying means; and

discriminating the operability of said vehicle safety system from a result obtained in said detecting steps.

2. A method as claimed in claim 1, wherein the circuit change is made by changing a value of a circuit element of said first or second differential amplifying means, whereby one of said first and second differential amplifying means is changed in the arrangement so as to be able to respond to an in-phase input.

3. A method as claimed in claim 2, wherein the circuit element is bridged by a switching means to substantially change the value of the circuit element.

4. A method as claimed in claim 1, wherein a test signal is applied to said acceleration sensing means to produce the pair of check signals.

5. A method as claimed in claim 4, wherein a value of at least one circuit element of said first or second differential amplifying means is changed, whereby one of said first and second differential amplifying means is rendered responsive to an in-phase input.

6. A method as claimed in claim 5, wherein the circuit element is bridged by a switching means to substantially change the value of the circuit element.

7. A method as claimed in claim 6, wherein the test signal is also applied to the switch means to close the same, whereby one of said first and second differential amplifying means is rendered responsive to the check signals.

8. A method for checking operability of a vehicle safety system, which comprises a vehicle safely device;

a firing member for activating said vehicle safety device;

an acceleration sensing means for providing a pair of output signals which correspond to acceleration of a vehicle but are opposite in phase from each other;

a first discriminating means which includes a first differential amplifying circuit means responsive to said acceleration sensing means for producing a first detection signal corresponding to the difference between the pair of output signals and discriminates occurrence of collision of the vehicle in response to the first detection signal;

a second discriminating means which includes a second differential amplifying circuit means responsive to said acceleration sensing means for producing a second detection signal corresponding to the difference between the pair of output signals and discriminates the occurrence of collision of the vehicle in response to the second detection signal;

a first means responsive to said first discriminating means for allowing a current to flow therethrough between one terminal of said firing member and a power source when the occurrence of collision of the vehicle is discriminated by said first discriminating means; and

a second means responsive to said second discriminating means for allowing a current to flow therethrough between the other terminal of said firing member and the power source when the occurrence of collision of the vehicle is discriminated by said second discriminating means;

whereby a firing current is allowed to flow through said firing member from the power source when both said first and second means are rendered operative at the same time, said method comprising the steps of;

causing said acceleration sensing means to produce a pair of check signals which are identical;

making a circuit change in said first differential amplifying circuit means to enable it to respond to an in-phase input;

detecting whether or not a potential difference is developed across said firing member in response to the circuit change in said first differential amplifying circuit means;

canceling the circuit change in said first differential amplifying circuit means to make it unable to respond to an in-phase input;

changing a circuit arrangement of said second differential amplifying circuit means so as to be able to respond to an in-phase input; and

detecting whether or not a potential difference is developed across said firing member in response to the circuit change in said second differential amplifying circuit means;

whereby one system for actuating said first means and another system for actuating said second means are checked independently at different times.