Apparatus for recording an operating condition of a vehicle safety device

• US 4,968,965 A
• Filed: 05/31/1989
• Issued: 11/06/1990
• Est. Priority Date: 06/01/1988
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Kondo, Akira, Masegi, Mitsuhiko, Naitou, Motoharu
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Swarthout, Brent A.
• Application Number:
  US07/359,282
• Time in Patent Office: 524 Days
• Field of Search: 340/436, 340/438, 180/274, 180/282, 280/735, 307/10.1
• US Class Current: 340/436
• CPC Class Codes: B60R 21/0173 Diagnostic or recording means therefor
• CPC Class Codes: G07C 5/085 using electronic data carriers

Abstract

An acceleration sensor detects an acceleration of a vehicle which is caused by a collision of the vehicle. A safety device protects an occupant in the vehicle from the collision of the vehicle. A trigger device triggers the safety device. The trigger device is activated in response to an output signal from the acceleration sensor. An operation of the trigger device is detected and a detection signal representative thereof is generated. A first judgment device judges whether or not the trigger device is activated on the basis of the detection signal. When the trigger device is judged to be activated, a second judgment device judges whether the activation of the trigger device is caused by a correct cause or a false cause on the basis of the output signal from the acceleration sensor. The judgment by the second judgment device is allowed only once and subsequent judgments by the second judgment device are inhibited. A result of the judgment by the second judgment device is recorded.

Claims

1. An apparatus for recording an operating condition of a vehicle safety device, comprising:

means for triggering the safety device when supplied with an electric current equal to or greater than a reference electric current;

means for detecting an acceleration of a vehicle which is caused by a collision of the vehicle, and outputting an electric signal depending on the detected vehicle acceleration;

means for deciding whether or not the triggering means should be activated on the basis of the electric signal from the acceleration detecting means;

switch means, turned on in response to an output signal from the deciding means, for supplying an electric current equal to or greater than the reference electric current to the triggering means to activate the triggering means;

means for detecting voltages at respective two ends of the triggering means;

means for detecting an activating condition of the triggering means on the basis of the detected voltages;

activation storing means for storing the detected activating condition of the triggering means;

collision storing means for, when the acceleration detecting means detects the collision acceleration, storing the detection of the collision acceleration by the acceleration detecting means;

means for judging the triggering means to be activated by a correct cause in cases where, during a predetermined time starting from a moment of the detection of the collision acceleration by the acceleration detecting means, the activation storing means stores the activating condition of the triggering means and the collision storing means stores the detection of the collision acceleration by the acceleration detecting means, for judging the triggering means to be activated by a false cause in other cases, and for outputting a signal representing a result of the judgments;

means responsive to the output signal from the judging means for recording that the triggering means is activated by a false cause; and

means for limiting a number of times of the judgments by the judging means to one.

2. An apparatus for recording an operating condition of a vehicle safety device, comprising:

a squib for triggering the safety device when supplied with an electric current equal to or greater than a reference electric current;

an acceleration sensor for detecting an acceleration of a vehicle which is caused by a collision of the vehicle, and outputting an electric signal depending on the detected vehicle acceleration;

a fire decision circuit for deciding whether or not the squib should be fired on the basis of the electric signal from the acceleration sensor;

a first switch, connected to the squib and turned on in response to a fire signal from the decision circuit, for supplying an electric current equal to or greater than the reference electric current to the squib to fire the squib;

a first connection point and a second connection point connected to respective two ends of the squib and conducting voltages at the respective two ends of the squib;

a second switch turned on and outputting a first signal when a voltage at the first connection point is equal to or higher than a first reference voltage;

a third switch outputting a second signal when a voltage at the second connection point exceeds a second reference voltage;

a fourth switch outputting a third signal depending on the electric output signal from the acceleration sensor;

a microcomputer performing calculation processes on the basis of the first signal, the second signal, and the third signal;

a memory receiving an output signal from the microcomputer;

wherein the microcomputer comprises;

means for judging whether or not the squib is fired on the basis of the first signal and the second signal;

means for, when the squib is judged to be fired, judging the fire of the squib to be performed by a false cause in cases where the acceleration sensor does not output an electric signal of a level equal to or higher than a predetermined level for a last predetermined time interval;

means for recording information into the memory, the information representing that the fire of the squib is performed by the false cause; and

means for limiting a number of times of the recording of the information into the memory to one.

3. An apparatus for recording an operating condition of a vehicle safety device, comprising:

a squib for triggering the safety device when supplied with an electric current equal to or greater than a reference electric current;

an acceleration sensor for detecting an acceleration of a vehicle which is caused by a collision of the vehicle, and outputting an electric output signal depending on the detected vehicle acceleration;

a fire decision circuit for deciding whether or not the squib should be fired on the basis of the electric signal from the acceleration sensor;

a first switch, connected to the squib and turned on in response to a fire signal from the decision circuit, for supplying an electric current equal to or greater than the reference electric current to the squib to fire the squib;

a first connection point and a second connection point connected to respective two ends of the squib and conducting voltages at the respective two ends of the squib;

a second switch turned on and outputting a first signal when a voltage at the first connection point is equal to or lower than a first reference voltage;

a third switch outputting a second signal when a voltage at the second connection point exceeds a second reference voltage;

a fourth switch outputting a third signal in response to the electric output signal from the acceleration sensor which has a level equal to or greater than a predetermined level, the third signal having a predetermined short duration;

a storage circuit set in response to the first signal and the second signal and outputting a fourth signal only once when being set, the fourth signal having a predetermined short duration;

a fifth switch for judging whether the fire of the squib is performed by a correct cause or a false cause on the basis of the third signal and the fourth signal, and for outputting a false-fire-representing signal when the fire of the squib is performed by the false cause; and

a memory for recording the false-fire-representing signal.