JPH04176756A - Collision detecting device - Google Patents

Abstract

PURPOSE:To ensure the safety of passengers by judging whether the charged voltage of a charge/discharge means is a determined value or more, detecting the peak value of the output of an acceleration sensor, judging whether this peak value is a determined value or more, and detecting the coincidence between these judgment results to conduct collision judgment. CONSTITUTION:A comparing means 6 compares the output level of an acceleration sensor 1 with a determined value, and a charge/discharge means 10 conducts charge/discharge according to the comparison result of the comparing means 6. A first comparing means 12 compares the charged voltage of the charge/ discharge means 10 with a determined value. A peak holding means 16 detects the peak value of the output of the acceleration sensor 1, and a second comparing means 17 compares the peak value of the peak holding means 16 with a determined value. The coincidence between the comparison results of the first and second comparing means 12, 17 is detected to conduct collision judgment. Thus, a collision can be highly precisely detected without error, and the safety of passengers can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a collision detection device used in a system for detecting a vehicle collision and activating an air pack to ensure the safety of occupants.

BACKGROUND OF THE INVENTION A conventional collision detection device for an air pack system uses a mechanical device in which a spring is attached to a cylindrical roller and the switch is turned on by the roller that moves against the elastic force of the spring in the event of a collision. was.

Problems to be Solved by the Invention However, since the conventional device described above is a purely mechanical collision detection device, there is a problem in that the detection accuracy of detection parameters such as acceleration generated at the time of a collision is low.

The present invention solves the above-mentioned conventional problems, and provides a collision detection device with high detection accuracy and fewer false detections.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a comparison means for comparing the output level of an acceleration sensor with a predetermined value, and a charging/discharging means for charging and discharging according to the comparison result of the comparison means. a first comparing means for comparing the charging voltage of the charging/discharging means with a predetermined value; a peak hold means for detecting a peak value of the output of the acceleration sensor; and a first comparison means for comparing the peak value of the peak hold means with a predetermined value. a second comparison means for
The present invention is characterized in that it includes means for detecting a match between the comparison results of the second comparing means.

Operation The present invention has the above-described configuration, and compares the signal output from the acceleration sensor at the time of a collision with a predetermined value, charges or discharges the charging/discharging means according to the comparison result, and adjusts the charging voltage of the charging/discharging means. The first comparison means determines whether or not the output is greater than or equal to a predetermined value, and the peak value of the output of the acceleration sensor is detected, and the second comparison means determines whether or not this peak value is greater than or equal to the predetermined value. Collision is determined by detecting a match between the comparison results of the means.

EXAMPLE An example of the present invention will be described below with reference to the drawings. 1e shows a collision detection device in one embodiment of the present invention. In FIG. 1, l is an acceleration sensor using a piezoelectric element, 2 is a capacitor, and 3.4.5 is a resistor, and the output signal of the acceleration sensor 1 is applied to the DC voltage set by the resistors 3 and 4. are superimposed. 6 is a comparator, and this comparator 6 compares the output signal level of the acceleration sensor 1 superimposed on the DC voltage with a predetermined voltage "v-r,"
When the output signal REHE/l of the acceleration sensor 1 becomes higher than the predetermined voltage V1, a low bell output signal L- is output. The output of comparator 6 is applied via resistor 7 to the base of transistor 8. The output of the comparator 6 is a low level "L" of the transistor 8.
When the temperature reaches 10°, the capacitor 10 is turned on and current flows through the resistor 9 to charge the capacitor 10. 11 is a resistor 11 connected in parallel to the capacitor lO;
Together, they form a discharge circuit. Resistance value of resistor 9 (R9)
is a value sufficiently smaller than the resistance value (R1+) of the resistor 11, so the charging time constant (R9XCIO) for charging the capacitor 10 (capacitance C+0) is the discharging time constant (Rth XCID)
Therefore, it is charged every time the output level of the acceleration sensor 1 becomes thicker than the predetermined voltage V1. 12 is a comparator that compares the voltage charged in the capacitor 10 and a predetermined voltage v2, and when the charging voltage becomes larger than the predetermined voltage v2, the output of the comparator 12 becomes a high level "H-".1
3 is an inverter that inverts the output of the comparator 12;
The output of this inverter 13 is applied to the base of a transistor 15 via a resistor 14. With the above configuration, the first
A judgment circuit is constructed, and the level “H” is higher than that of the comparator 12.
By outputting , it is possible to detect the occurrence of a collision.

(a) to (d) of FIG. 2 show the operation of the first determination circuit. In FIG. 2(a), A is the output waveform of the acceleration sensor 1 when an impact is applied, and when the output level of the acceleration sensor 1 becomes higher than the predetermined voltage Vl, as shown in FIG. 2(b), The output of comparator 6 is low level "L-"
Conversely, when the output level of the acceleration sensor 1 becomes lower than V+, the output of the comparator 6 becomes a high level -H''.Second
Figure (C) shows the voltage of the capacitor 10. When the output of the comparator 6 becomes a low level "L-", the transistor 8 is turned on and the capacitor 10 is charged, and when the output of the comparator 6 becomes a high level "H", the transistor 8 is turned off and the capacitor 10 is discharged. FIG. 2(d) shows the output of the comparator 12.The output of the comparator 12 becomes a high level "H-" when the voltage of the capacitor 10 becomes higher than the predetermined voltage v2, and when the voltage of the capacitor 10 becomes lower than the predetermined voltage v2. Then, the level becomes low -L-. The transistor 15 is turned on when the output level of the comparator 12 becomes "-H", and turned off when the comparator level becomes "L-".

Next, the second determination circuit will be explained with reference to FIG.

In FIG. 1, 16 is a comparator 16A1 diode 16
Peak hold section consisting of B1 capacitor 16C, 17
18 is a resistor, 19 is a transistor,
20 is an analog switch, 21 is a comparator that compares the output level of the acceleration sensor 1 and a predetermined voltage v4, and 22 is a retriggerable mono-multi-by-break. In FIG. 1, the voltage v4 applied to one input terminal of the comparator 21 is set higher than the ground noise level of the acceleration sensor 1. Therefore, when a vehicle collides and the acceleration sensor 1 outputs a signal higher than the voltage v4, the comparator 21 outputs a signal of high level "H-" and the vehicle collision is detected. The mono multivibrator 22 is driven and outputs a low bell "L" signal for a certain period of time.The high level of the mono multivibrator 22 is "H".
The ``output'' causes the analog switch 20 to close, and the low level ``L-'' output of the multivibrator 22 causes the analog switch 20 to open. analog switch 20
operates as a switch to reset the peak hold section 16, and while the mono multivibrator 22 is -L- (that is, at the time of a vehicle collision), the peak hold section 16 performs a peak hold operation, and the output signal of the acceleration sensor 1 is Halt the peak value. The comparison section 17 compares the output of the peak hold section 16 with a predetermined voltage V3, and outputs a high level °H" if the output of the peak hold section 16 is equal to or higher than v3. When the voltage is applied to the transistor 19 and the output of the comparator 17 is "H", the transistor 19 is turned on.

FIGS. 2(e) to 2(g) show the operation of the second determination circuit. FIG. 2(e) shows the output of the mono-multivibrator 22 which can be retriggered, and shows the output of the acceleration sensor 1.
It is triggered every time the output level of the mono multivibrator 22 exceeds V4, and after a predetermined time from the last trigger signal, it is reversed and becomes -H" level. During the period when the output of the mono multivibrator 22 is "H", the analog switch 20 is turned on. The level at the output end of the peak hold section 16° is maintained at the midpoint potential of the acceleration sensor 1 (VO in FIG. 2 a), and the peak value is output from the peak hold section 16 during the period when the analog switch 20 is off. 2(f) shows the peak hold section 1.
6 output, and the mono multivibrator 22 is “L-
The peak value of the output of the acceleration sensor 1 is held during the level period.

The output of the peak hold section 16 is input to the comparison section 17,
It is compared with a predetermined voltage v3. FIG. 2(g) shows the comparison section 17.
The comparator 17 shows the output of the peak hold unit 1.
6 outputs -H- during the period when the output is higher than the voltage v3.

The -H" output of the comparator 17 is applied to the terminal of the transistor 19 via the resistor 18, turning on the transistor 19. FIG. 2(h) shows the voltage applied to the ignition squib 23. During the period when both transistors 15 and 19 are on, current is supplied to the ignition squirt 24 from the battery 24, so the ignition squirt 24 is activated and activates an air bag or the like.

As described above, according to the above embodiment, the waveform in which the signal continues to be higher than a predetermined level and the peak value higher than the predetermined level are determined from the signal output from the acceleration sensor 1 when a vehicle collides, and a collision occurs. Since this is a detection method, there is an advantage that collision detection with high detection accuracy and no error is possible. Furthermore, this embodiment has the advantage that the air pack activation conditions can be easily set by adjusting the voltages V+, v2, V3, and v4, the charging time constant, and the discharging time constant.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the connection of the diode of the peak hold section 16 of the embodiment shown in FIG.
7 is connected to an inverter 17c. This embodiment detects the peak value of the negative side signal output from the acceleration sensor 1 at the time of a vehicle collision, and the voltage v5 of the comparator 17 is equal to the midpoint potential (vO) in FIG. 2(a). It is set on the more negative side. According to the embodiment shown in FIG. 3, a collision is detected by determining the characteristics of the signal generated from the acceleration sensor 1 at the time of a collision, that is, the point where the signal continues at a certain level or more, and the point where a signal with a large level on the negative side is generated. It can be done.

In the embodiment shown in FIG. 3, if the two-man power applied to the comparing section 17 is reversed, the inverter 17c becomes unnecessary.

As described above, according to the above embodiment, the integral value of the acceleration sensor output equal to or higher than the predetermined level and the higher peak value are respectively detected by the first and second determination circuits, and the determination results of both circuits are Since the air pack or the like is activated based on the coincidence of the two, highly accurate collision detection without detection errors is possible. Further, according to the second embodiment, a negative signal output from the acceleration sensor at the time of a collision can also be detected.

Effects of the Invention The present invention has the above-described configuration, and determines whether or not the signal output from the acceleration sensor at the time of a vehicle collision continues at a predetermined level or higher, and also detects the peak on the plus or minus side. Collision detection is performed by determining whether the value is equal to or higher than a predetermined level, which has the advantage of enabling highly accurate and error-free collision detection.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a collision detection device according to an embodiment of the present invention, and FIGS. 2(a) to (h) are operational explanatory diagrams of the device.
FIG. 3 is a block diagram of a portion of another embodiment of the invention. 1... Acceleration sensor, 2... Capacitor, 3.4.
5...Resistor, 6...Comparator, 7...Resistor, 8...
・Transistor, 9... Resistor, 10... Capacitor, 11... Resistor, 12... Comparator, 13... Inverter, 14... Resistor, 15... Transistor, 1
6... Peak hold section, 17... Judgment section, 18.
...Resistor, 19...Tara resistor, 20...Analog switch, 21...Comparator, 22...Mono multivibrator, 23...Ignition squib, 24...Battery.

Claims (2)

[Claims] (1). Comparing means for comparing the output level of the acceleration sensor with a predetermined value, charging/discharging means for charging/discharging according to the comparison result of the comparing means, and a first comparing the charging voltage of the charging/discharging means with a predetermined value. a second comparing means, a peak holding means for detecting the peak value of the output of the acceleration sensor, and a second comparing means for comparing the peak value of the peak holding means with a predetermined value.
A collision detection device comprising: comparing means; and means for detecting a match between the comparison results of the first and second comparing means. (2). 2. The collision detection device according to claim 1, wherein the predetermined value of the second determining means is set on the plus or minus side with respect to the midpoint of the acceleration sensor.