Crash sensor

• US 5,189,311 A
• Filed: 01/24/1991
• Issued: 02/23/1993
• Est. Priority Date: 01/29/1990
• Status: Expired due to Term

• Current Assignee: Autoliv Japan Limited (Autoliv Incorporated)
• Original Assignee: Sentech Co., Ltd. (Omron Corporation)
• Inventors: Moriyama, Hiroshi, Sada, Hiroyuki, Shiozawa, Takeo
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Krishnan, Aditya
• Application Number:
  US07/645,258
• Time in Patent Office: 761 Days
• Field of Search: 364/424.01, 364/424.05, 280/735, 180/274, 180/282, 180/281, 340/456, 340/458, 307/10.1, 307/121
• US Class Current: 307/10.1
• 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 21/0133 by integrating the amplitude of the input signal
• CPC Class Codes: B60R 21/01332 by frequency or waveform analysis

Abstract

An electronic crash sensor which can operate appropriately in response to any form of crash of a vehicle. An input acceleration waveform from an accelerometer is first processed to peak cut any portion thereof lower than a predetermined value. Then, a value obtained such peak cutting is time integrated. Then, a time integrated value of a predetermined function is subtracted from a value obtained by such time integration. Then, the value of the acceleration waveform thus obtained is compared with a predetermined time function value, and when the former is higher than the latter, a triggering signal is delivered to a trigger circuit to trigger operation of a passenger protecting apparatus such as an air bag of the vehicle.

Claims

1. A crash sensor which detects crash of a vehicle from an acceleration waveform of an accelerometer to trigger operation of a passenger protecting apparatus, comprising:

means for peak cutting any portion of the inputted acceleration waveform lower than a predetermined value;

means for time integrating a value obtained by such peak cutting;

means for subtracting a time integrated value of a predetermined function Δ

V per unit time from a value obtained by such time integration; and

means for comparing a value obtained by such subtraction with a predetermined time function value to develop a triggering signal.

3. A crash sensor according to claim 1 or 2, further comprising an AND circuit for receiving a signal indicative of a speed higher than a predetermined level from a speedometer and a signal from said comparing means to develop a triggering signal.

4. A crash sensor according to claim 1 or 2, wherein the predetermined time function value is varied in response to a speed of said vehicle from a speedometer directly before the crash.

5. A crash sensor according to claim 1 or 2, wherein a K-th power of an acceleration waveform is inputted as the acceleration waveform.

6. A crash sensor according to claim 1 or 2, wherein the time integration is n-th time integration.

7. A crash sensor according to claim 1 or 2, wherein an amplified acceleration waveform is inputted as the acceleration waveform.

8. A crash sensor according to claim 1 or 2, wherein a waveform obtained by subtraction from an acceleration waveform obtained by means of a filter processing from the acceleration waveform is inputted as the acceleration waveform.

9. A crash sensor according to claim 1 or 2, wherein the time integrating operation is reset when the time integrated value to be compared with the predetermined time function value comes to a value around zero.

2. A crash sensor which detects crash of a vehicle from an acceleration waveform of an accelerometer to trigger operation of a passenger protecting apparatus, comprising:

means for subtracting a first predetermined value from said waveform to define an upper area above said first predetermined value and a bottom area below said first predetermined value;

means for subtracting a second predetermined value from the inputted acceleration waveform to reduce the size of said bottom area;

means for time integrating said upper area and the reduced size bottom area; and

means for comparing a value obtained by such time integration with a predetermined time function value to develop a triggering signal.

10. A crash sensor which detects a vehicle crash from an acceleration waveform of an accelerometer to trigger the operation of a passenger protecting apparatus, comprising:

means for separating said waveform into positive peaks representing a vehicle deceleration in excess of a first predetermined threshold deceleration value and a bottom portion representing decelerations not in excess of said first predetermined threshold deceleration value, said positive peaks defining a positive area between said acceleration waveform and a line representing said first threshold deceleration value and said bottom portion defining a negative area between said acceleration waveform and said line representing said first threshold deceleration value;

means for cutting from said negative area all values between a second threshold deceleration value and said acceleration waveform to leave a smaller negative area;

means for integrating said positive area and said smaller negative area to produce an integration curve; and

means for comparing values from said integration curve with values from a predetermined time function to develop a triggering signal when the integration curve value exceeds the predetermined time function value.