JPH03243445A - Control system for vehicle safety device - Google Patents

Abstract

PURPOSE:To improve safety by integrating the deceleration of a vehicle, comparing this integrated value with a set value to judge collision, and operating a vehicle safety device according to the judgment, as well as lowering the set value with the increase of deceleration so as to prompt the operation of a vehicle safety device. CONSTITUTION:In the control system of a vehicle safety device 1, the deceleration of a vehicle is detected by an acceleration detecting means 2, and the detected deceleration is integrated by an integrating arithmetic means 3. The integrated value is compared with a threshold level, and the existence of collision is judged by a collision judging means 4, as well as an operation command signal is outputted upon judging collision. On the basis of the outputted operation command signal, the vehicle safety device 1 is operated by a driving circuit 5. On the other hand, with the increase of the above-mentioned detected deceleration, a deceleration compensating means 6 performs compensation to lower the above-mentioned threshold level. The operation of the vehicle safety device 1 is thereby prompted when collision is intense, and thus safety is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control system for a vehicle safety device.

BACKGROUND ART Systems for controlling vehicle safety devices such as air vents are known as disclosed in Japanese Unexamined Patent Publication No. 49-55031 and Japanese Utility Model Application No. 2-5371.

This control system includes an acceleration detection means for detecting the deceleration of the vehicle, an integral calculation means for integrating the deceleration from the acceleration detection means, and a comparison of the integral value from the integral calculation means with a threshold level to determine whether or not a collision has occurred. a collision determining means that determines a collision and outputs an activation command signal when determining that there is a collision, and a drive circuit that supplies current to the squib of the airbag to inflate the airbag in response to the activation command signal from the collision determining means. It is equipped with

[Problems to be Solved by the Invention] In the above control system, the time from the start of deceleration due to a vehicle collision to the completion of inflation of the airbag is determined by the following first
determined by the sum of the time and the second time. The first hour is
This is the time from the start of deceleration until the integral value of deceleration reaches a threshold level and an operation command signal for supplying current to the valve is output. The second time is the time from when current begins to flow through the squib in response to the activation command signal until the inflation of the airbag is completed.

In the event of a severe vehicle collision, in other words, if a sudden deceleration occurs in a short period of time, the time from the start of deceleration until the occupants are strongly pushed forward by inertia is shortened, so The airbag needs to be inflated.

In the above control system, when the deceleration is large, the integral value of the deceleration also reaches the threshold level quickly, so the first time can be shortened. However, the second
Since the time is constant, there is a possibility that the sum of the first time and the second time cannot be shortened sufficiently. In order to eliminate this fear, it is necessary to lower the threshold level.

On the other hand, if the collision is gradual, in other words, if deceleration occurs over a relatively long period of time, the inertial force applied to the occupant is small, so there is no risk of the occupant colliding with the steering wheel or the like. Therefore, in this case, it is necessary to prevent the airbag from inflating. However, even though the deceleration is small, the integral value increases as time passes, so
There was a risk that the above threshold level would be reached and the airbag would malfunction. In order to eliminate this fear, the threshold level must be set high so that the integral value does not easily reach the threshold level.

As is clear from the above explanation, although on the one hand it is required to lower the threshold level and on the other hand it is required to increase it, in conventional control systems, the threshold level is constant, so it is difficult to maintain both. It was not easy to satisfy.

[Means for Solving the Problems] The invention of claim 1 has been made to solve the above problems, and its gist resides in a control system for a vehicle safety device 1 shown in FIG. That is, the control system includes an acceleration detection means 2 for detecting the deceleration of the vehicle, an integral calculation means 3 for integrating the deceleration from the acceleration detection means 2, and an integral value obtained by the integral calculation means 3 as a threshold level. Collision determination means 4 that compares and determines the presence or absence of a collision and outputs an activation command signal when it is determined that there is a collision, and a drive circuit that activates the vehicle safety device 1 based on the activation command signal from the collision determination means 4. 5.

Furthermore, the control system includes deceleration compensation means 6 for lowering the threshold level as the deceleration increases.

The gist of the invention of claim 2 is that, in addition to the configuration of the invention of claim 1, the present invention includes a vehicle speed detection means and a relationship between a threshold level and deceleration that is changed in accordance with the vehicle speed from the vehicle speed detection means. The present invention provides a control system for a vehicle safety device, comprising vehicle speed compensating means for lowering the threshold level as the vehicle speed increases.

The invention according to claim 3 provides, in addition to the configuration of the invention according to claim 1, a time measuring means that starts measuring the elapsed time when the integral value reaches a predetermined level lower than the threshold level;
A control system for a vehicle safety device comprising time compensation means for changing the relationship between a threshold level and deceleration according to the elapsed time.

[Function] In the invention of claim 1, when a vehicle violently collides, in other words, when a sudden deceleration occurs in a short period of time, the threshold level is lowered according to the large deceleration, and the integral of the deceleration is calculated. The value reaches the threshold level quickly, and vehicle safety devices are activated quickly. Therefore, even if the time from the start of deceleration to when the occupant moves forward due to inertia force is short, the time can be made sufficiently, and the safety of the occupant can be ensured.

On the other hand, if the collision is gradual, in other words if a small deceleration occurs over a relatively long period of time, the threshold value will be increased. Therefore, even if the integral value of the deceleration increases over time, it does not easily reach the threshold level, thereby preventing the vehicle safety device from malfunctioning.

The invention of claim 2 takes into consideration that when the vehicle speed is high, there is a high possibility that a severe collision will occur, and when the vehicle speed is low, there is a high possibility that the impact will be an instantaneous impact other than a collision or a relatively gentle collision. be. In other words, by lowering the above-mentioned thread and torque levels as the vehicle speed increases, a synergistic effect with the above-mentioned acceleration compensation can be obtained, and the vehicle safety device can be activated more quickly in the event of a severe collision, and the malfunction of the vehicle safety device can be prevented. This can be prevented more reliably.

In the invention of claim 3, in consideration of the fact that the manner in which deceleration changes depending on, for example, an instantaneous impact other than a collision, a severe collision, and a relatively gentle collision, when the integral value of the deceleration value reaches a predetermined level, The relationship between the threshold level and acceleration is changed depending on the elapsed time since the start.

This makes it possible to accurately determine whether or not the vehicle safety device should be activated in response to various impacts applied to the vehicle.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. 2, FIG. 3, and FIG. FIG. 2 schematically shows a control system that controls squib 1 of the air hack vehicle safety device. The squib 1 is incorporated into a drive circuit 10. The drive circuit 10 includes a transformer/metal 1 connected to one end of the ground side of the squib 1.
1. Between the squib 1 and the power source 14, an energy reservoir (not shown) consisting of a large capacity capacitor and a booster for making the voltage of the energy reservoir higher than the power supply voltage are installed in order from the squib to the power supply. A circuit (not shown) is interposed.

The control system includes an acceleration senosing circuit 20 (acceleration detection means) including an acceleration sensor. This acceleration sensing circuit 20 outputs a voltage signal corresponding to the acceleration of the vehicle. That is, when the vehicle is accelerating, it is lower than 2.5V, and when the vehicle is decelerating, it is lower than 2.5V.
A voltage higher than 5V is output.

The voltage signal of the acceleration sensing circuit 20 is inverted and amplified by the inverting amplifier circuit 30. To explain in detail, the inverting amplifier circuit 30
includes an operational amplifier 31, a variable resistor 32 connected to the operational amplifier 31 in a negative feedback manner, and an input resistor 33.

A reference voltage Vr of 2.5 V is inputted from an auxiliary constant voltage power supply 34 to a non-inverting input terminal of the operational amplifier 31 via a resistor 35. Therefore, the inverting amplifier circuit 30 has a voltage of 2.5V.
A voltage obtained by inverting and amplifying the voltage signal from the acceleration sensing circuit 20 with the center at the center is output. In other words, the output voltage will be higher than 2.5V during acceleration and 2.5V during deceleration.
becomes lower. Note that by adjusting the gain using the variable resistor 32, acceleration-output voltage characteristics equivalent to those obtained using the reference acceleration sensor can be obtained.

The voltage from the inverting amplifier circuit 30 is integrated by an integrating circuit 40 (integral calculation means). The integrating circuit 40 includes an operational amplifier 41 connected in negative feedback via a capacitor 42, and input resistors 43 and 44 connected to the inverting input terminal of the operational amplifier 41. An offset voltage Vos is input to a non-inverting input terminal of this operational amplifier 41.

This offset voltage VO5 is applied to the auxiliary constant voltage power supply 34.
It is obtained by dividing the voltage of 2.5V by a resistor of 45.46, for example, 2.5V. It is Ov.

When the integrating circuit 40 receives a voltage lower than the offset voltage VOS (20V) from the inverting amplifier 30, it integrates this voltage to increase the output voltage, resulting in an offset voltage of 11 voltage Vos.
When receiving a higher voltage, the output voltage decreases. In other words, the difference between the reference voltage Vr and the offset voltage Vos (0
, 5V), the output voltage increases and an integral calculation of the deceleration is performed.

Further, the output voltage of the integrating circuit 40 decreases not only when the vehicle is in an accelerating state but also when the deceleration of the vehicle is less than the deceleration corresponding to the above-mentioned 0.5V.

Integrating circuit 40 further includes a comparator 47. The non-inverting input terminal of the comparator 47 is connected to the operational amplifier 4.
1 output voltage. The inverting input terminal of the comparator 47 receives a minute voltage of 100 mV from the minute voltage power supply 48 . When the voltage applied to the operational amplifier 41 from the inverting amplifier circuit 30 is higher than the offset voltage VO8, the output of the operational amplifier 41 does not decrease to zero V but is maintained at 100 mV. To explain in detail, the output of the operational amplifier 41 is 100m
When the voltage drops even slightly below V, the comparator 47 switches to O- level, thereby increasing the output of the operational amplifier 41. If the output of the operational amplifier 41 exceeds even slightly 10QmV, the comparator 47 switches to high impedance, and the output of the operational amplifier 41 decreases. This results in
It is possible to prevent the operational amplifier 41 from becoming saturated with an output voltage of zero V, and to maintain the output of the integrating circuit 40 in a linear region at all times.

The output of the integrating circuit 40 is input to a non-inverting input terminal of a comparator 50 (collision determining means). A threshold voltage generation circuit 60 (
The threshold voltage from the deceleration compensation means) is input. This threshold voltage generation circuit 60 includes a resistor 61
．． It consists of 62 series circuits, one end of which is connected to the constant voltage circuit Vcc, and the other end connected to the output stage of the inverting amplifier circuit 30. The voltage at the connection point between the resistors 61 and 62 is then provided to the comparator 50 as a threshold voltage vth. This threshold voltage vth can be expressed by the following equation.

V th= (Vcc-Vg)' Rat/ (Ra
t+Rat)+Vg-(1) As is clear from this equation, the threshold voltage vth changes linearly with the voltage Vg representing deceleration. That is, as shown by the characteristic line in FIG. 3, as the deceleration G increases, the threshold voltage vth decreases.

Since the inverting amplifier 30 has a single power supply, even if the actual deceleration G is very large, the output voltage Vg of the inverting amplifier 30 does not become negative, and its lower limit is zero V. Therefore, the lower limit value vt of the threshold voltage vth
h is determined by substituting Vg=0 into the above equation (1), and is expressed by the following equation.

Vtha=Vcc-Rat/(Rat+Rst)
In the above configuration, the comparator 50 compares the output from the integrating circuit 40 representing the integral value of deceleration with the threshold level vth, and when the former exceeds the latter, the output is set to high level and the transistor 11 is turned on. . As a result, the skin l receives current from the energy reservoir and is ignited to inflate the air pack.

As described above, the threshold voltage vth decreases as the deceleration increases, so when the collision is severe and the deceleration is large, the integral output, which is the integral value of the deceleration, becomes faster and the threshold voltage Vth decreases. reached and skin 1 can be ignited.

Thereby, the air pack can be expanded quickly to ensure the safety of the occupants.

Also, contrary to the above, if the collision is gentle enough that there is no need to inflate the air pack, and the deceleration of the vehicle is small,
Since the threshold voltage vth increases, even if the integrated output increases over time, it does not reach the threshold vth. This makes it possible to prevent the air pack from malfunctioning. In addition, if the collision is not severe but is such that it is necessary to inflate the air pack to protect the safety of the occupants, the integral value of the deceleration will be equal to the threshold voltage vt.
It takes a relatively long time to reach h.

However, in this case, since the time from the start of the collision until the occupant moves forward is relatively long, there is no problem in ensuring the safety of the occupant.

In addition, since the threshold level voltage Vth maintains a constant lower limit value Vth even if the g speed increases, even if a very large deceleration occurs due to an instantaneous shock, the integrated voltage will remain at the threshold level. Lower limit value of noshold voltage vth
, and from this point as well, it is possible to prevent the airbag from malfunctioning.

Although the above embodiment is a control system using an analog circuit, it goes without saying that the present invention can also be applied to a control system using a microcomputer. All of the control system examples described below use microfumulators.

Using a microcomputer, it is possible not only to perform the same control as in the above embodiment, but also to perform more precise control that takes into account vehicle speed, elapsed time at the time of impact, and the like.

The control system shown in FIG.
It is equipped with In this figure, components corresponding to those in FIG. 2 are given the same numbers and detailed explanation thereof will be omitted. A voltage signal representing acceleration is input from the acceleration sensing circuit 20 to an analog-to-digital converter 71 built into the microcomputer 70, where it is converted into digital data. The microcomputer 70 receives signals from a vehicle speed sensor 72 (vehicle speed detection means) 4, a passenger switchboard, and a rear seat 3. The vehicle speed sensor 72 outputs pulses as the axle rotates. The number of pulses from the vehicle speed sensor 72 over a certain period of time or the reciprocal of the time interval of the pulses represents the vehicle speed. The occupant switch 73 is installed at each seat of the vehicle, and is turned on when a person is seated. Therefore, the number of passenger switches turned on represents the number of passengers. In addition,
In the figure, a plurality of occupant switches are shown as one block.

The microcomputer 70 has a map A shown in FIG.
Use B and C. Each map A, B, and C has a characteristic line similar to the threshold voltage-deceleration characteristic line in FIG. That is, the horizontal axis represents the deceleration G, and the vertical axis represents the thread and shoulder level Th. Furthermore, as the deceleration G increases, the threshold level Th decreases.

In the above A, B, and C, the threshold level Th is constant at the upper limit Th in the region where the deceleration G is small. In a region where the deceleration G is intermediate, the threshold level Th has a substantially linear relationship with the m speed iG. In a region where the deceleration G is large, the threshold level T h is constant at the lower limit value T h.

The above maps A, B, and C differ from each other in the following points.

The lower limit value T h 2 of Threnoshort Rehel Th is Ma,
Map A is the highest, map C is the lowest, and map B is somewhere in between. Furthermore, the slope of the characteristic line in the intermediate region of the deceleration G is the gentlest for map A, the steepest for map C, and the slope for map B is in the middle. Therefore, the deceleration G
If they are equal, the threshold height Th is higher in the order of pine 7'A, B, and C.

The microcomputer 70 selects the maps A, B, and C according to the vehicle speed, and based on the selected maps, sets the threshold level Th according to the deceleration similarly to the embodiment shown in FIG. Determine.

The details will be explained below.

The microcomputer 70 executes the timer interrupt routine shown in FIG. First, the deceleration G is determined by multiplying the deceleration data from the acceleration sensor circuit 20 by a constant gain (step 100). Since the acceleration sensing circuit 20 has an error in the acceleration-output voltage characteristic of the reference acceleration sensing circuit, this gain is used to compensate for this error.

Next, the deceleration G is integrated (step 101). That is, the currently calculated deceleration G is added to the integral value ΔV stored in the RAM. Although not shown, when the deceleration G is below a predetermined level or when the acceleration is accelerated, a certain value is subtracted from the integral value ΔV. Next, vehicle speed v0 is calculated based on the signal from vehicle speed sensor 72 (step 102).

Next, a constant a corresponding to the number of passengers is determined based on the signal from the passenger switch 73 (step 103).

Note that the constant a will be described later, or the constant a is made smaller as the number of passengers increases.

Next, it is determined whether or not a tire lock condition occurs during sudden braking (step 104). Specifically, the speed V determined in step 105 or 106 (described later) in the previous routine and the speed ■ calculated this time. If the difference exceeds a predetermined value, it is determined that the tires are locked. Further, when it is determined that the tires are locked, it is determined that the tires are in a locked state at step 104 of the routine executed within a certain period of time thereafter.

When the tires are locked, the vehicle speed obtained from the vehicle speed sensor rapidly decreases to zero, but the vehicle is in a slipping state and gradually decelerates, but in reality it maintains a considerable vehicle speed.

When it is determined in step 104 that no tire lock has occurred, the vehicle speed V calculated in step 102 is calculated. of,
The actual vehicle speed V is determined (step 105). When it is determined that the tires are locked, the constant a determined in step 103 is subtracted from the previously determined speed V' to determine the actual speed V (step 106). In this way, the vehicle speed can be determined very accurately.

Note that the greater the number of occupants, the greater the kinetic energy of the entire vehicle, and the slower the deceleration during slipping. Considering this point, in step 103, the constant a is made smaller as the number of passengers increases, so that the actual vehicle speed V can be calculated more accurately.

Next, the vehicle speed V determined as above is 10 km/
It is determined whether or not it is lower than h (step 107). lQ
If it is determined that it is lower than Km/h, map A is selected (step 108).

If the determination in step 107 is negative, the vehicle speed V is 20
Determine whether it is lower than Km/h (Step 109)
. In case of affirmative judgment, IOKm/h≦v<
If it is determined that the speed is 20 Km/h, map B is selected (step 110). If it is determined that the speed is 20 km/h or more, select map C (step 111).
.

Next, based on the selected map, the threshold level Th corresponding to the acceleration is determined (step 11).
2) It is determined whether the integrated value ΔV of the deceleration has reached the threshold level Th (step 113). If the judgment is positive, jump to the collision control routine,
In this routine, a high-level operation command signal is output to the transistor 11 to cause the squib 1 to ignite. If the determination is negative, the process returns to the main routine.

As mentioned above, when the vehicle speed is high, M, 7'C, which has a low threshold Th relative to the deceleration G, is selected. When the vehicle speed is high, the impact at the time of a collision is likely to be large, and by selecting map C, the airbag can be inflated more quickly.

When the vehicle speed is low, map B having a high threshold level Th relative to the deceleration G is selected. When the vehicle speed is low, there is a high possibility that the impact will be relatively gentle, and by selecting M and B, malfunction of the airbag can be more reliably prevented.

If the vehicle speed is very low, map A with a high threshold level Th in a region where the deceleration G is large is selected.

This makes it possible to more reliably prevent the airbag from erroneously operating, especially when the vehicle is momentarily subjected to a very large deceleration such as a hammer blow during repair.

As is clear from the above description, in the routine shown in FIG. 6, steps 107 to 111 substantially constitute vehicle speed compensation means, step 112 constitutes deceleration compensation means, and step 113 constitutes collision determination means. It consists of

The microcomputer may select a map based on the elapsed time at the time of the collision. In this case, the microcomputer executes the timer interrupt routine of FIG. Note that in FIG. 7, the steps corresponding to those in FIG. 6 are given the same numbers and their explanations are omitted. Specifically, after the integral calculation in step 101, it is determined whether the integral value ΔV is less than or equal to a predetermined level ΔV (step 20
0). This predetermined level is much lower than the threshold level Th, and is the level of the deceleration integral value achieved by a relatively small impact.

If the determination is affirmative, the flag Ft is reset (step 201) and the process returns to the main routine.

This flag Ft indicates that a timer T (time measuring means), which will be described later, is filling an elapsed time meter.

If a negative determination is made in step 200, that is, if it is determined that the integral value ΔV exceeds the predetermined value Δv1, a preparation state for performing a collision determination is entered. First, it is determined whether the flag Ft is set (step 2
02). If it is not set, set the flag Ft (step 203), reset the timer T (step 204), and start counting the timer T (step 204).
Step 205), proceed to step 206. Step 2
If it is determined in step 02 that the flag Ft is set, steps 203 to 205 are passed and step 206 is executed.
Proceed to.

In step 206, it is determined whether the elapsed time measured by the timer T is less than the first set time Δ11. If it is determined that the value is less than 1, map A in FIG. 8 is selected (step 207).

When it is determined in step 206 that the elapsed time measured by the timer T is greater than or equal to the first set time ΔT1, the elapsed time measured by the timer T
Determine whether or not the set time ΔT7 is less than (step 208
). In case of affirmative judgment, elapsed time T or ΔT1≦T
If it is determined that ΔT is less than ΔT, map B in FIG. 8 is selected (step 209). If the determination is negative, that is, T≧ΔT, map C in FIG. 8 is selected (step 210).

Maps A, B, and C in FIG. 8 differ from each other in the following points. Threso 7 Yoltrehel Th lower limit Th.

Map C is the highest, Map B is the lowest, and Map A is in between. Further, regarding the slope of the characteristic line in the intermediate region of the deceleration G, map C is the gentlest, map B is the steepest, and map A is in the middle. therefore,
When the deceleration G is equal, the threshold level Th is lower in the order of maps B, A, and C, and squib ignition is performed earlier in this order.

The effect of the above map selection will be explained with reference to FIG. In addition, in FIG. 9, the upper side represents deceleration, and the lower side represents acceleration.

Map A was selected at the initial stage (T<ΔT,) as shown in Figure 9 (
This is to prevent the airbag from erroneously deploying when the vehicle receives a blow as shown in A). That is, the hammer blow imparts a large deceleration to the vehicle or is instantaneous, and the impact disappears within ΔT1 from the start of measurement. in this case,
By selecting the lower limit T h 2 of Threno/:I in the region of large deceleration G or a relatively high map A, the integral value does not reach the threshold level.

Map B was selected in the middle period (ΔT, ≦T<ΔT2) because
This is because there is no need to consider that the impact of the vehicle is a hammer blow, and preparations for rapid inflation of the airbag must be made keeping in mind a severe collision such as the frontal collision shown in Figure 9 (B), for example. .

In the latter stage (T≧ΔT), even if there is a collision, it is a gentle collision. However, even if the deceleration is relatively small, the integrated value is at a high level due to long integration. When an instantaneous shock accompanied by a high deceleration occurs, for example, a secondary collision, if the thread and shoulder levels decrease in response to the large deceleration, there is a possibility that the integral value will exceed the threshold level. Therefore, by selecting map C and setting a high threshold level during this period, it is possible to more reliably prevent airbag malfunction.

As is clear from the above description, steps 206 to 210 in the routine of FIG. 7 substantially constitute time compensation means.

In addition, in the microcomputer, instead of selecting a map in response to the vehicle speed or the elapsed time at the time of the collision, the scaling of the coordinate axes in one map may be substantially changed. That is, when determining the thread and shoulder levels, the deceleration to be substituted into the map is determined by adding to, subtracting from, or multiplying the deceleration by a constant determined according to the vehicle speed and elapsed time. Further, by adding to, subtracting from, or multiplying the integral value of deceleration by a constant determined according to vehicle speed and elapsed time, an integral value to be compared with the threshold level is determined.

Next, an embodiment will be described in which the deceleration to be substituted into the map and the integral value to be compared with the threshold level are changed by changing the acceleration key in accordance with the elapsed time at the time of the collision. In this case, the microcomputer uses one map shown in FIG. 11 to execute the timer interrupt routine shown in FIG. 10. In FIG. 10, steps corresponding to the routine in FIG. 7 are given the same numbers and detailed explanation thereof will be omitted. In this routine, the gain is calculated in accordance with the elapsed time T using the steering knob 300 instead of selecting the map.

To explain with reference to FIG. 12, the gain is set to a relatively large value A1 before starting measurement of elapsed time. At the start of measuring the elapsed time, the gain is lowered to a small value A, and as the time elapses, the gain is gradually increased and returned to A. The elapsed time is T. When it reaches A, the gain is lowered again to A.

If the gain is large, the deceleration G calculated in step 100 will be larger than the actual deceleration. That is, the deceleration G substituted into the map of FIG. 11 increases, and the threshold level is determined to be low. Furthermore, since the deceleration G increases, the integral value calculated in step 101 also increases quickly. This is effectively equivalent to lowering the threshold level. This allows the air pack to activate sooner. The opposite is true if the gain is small.

The reason why the gain is set to a large value A before starting measurement of the elapsed time is to make the integral value ΔV quickly reach the predetermined level Δv1 described above, and to accelerate the start of measuring the elapsed time.

The reason why the gain was lowered to A at the start of elapsed time measurement was to deal with hammer blows.

After that, the gain was increased again to A in order to prepare for rapid inflation of the air pack in anticipation of a severe collision.

The elapsed time is T. The reason why the gain was lowered to A2 again when this point was reached was to more reliably prevent the airbag from malfunctioning in the event of a gentle collision.

As is clear from the above description, in the routine of FIG. 10, step 300 constitutes time compensation means.

Note that the microcomputer may calculate the threshold level corresponding to the deceleration using a formula instead of using Ma-Tsub.

In this specification, lowering the threshold level according to the deceleration more strictly means lowering the absolute value of the threshold level. For example, in an embodiment where the deceleration appears as a negative value, the threshold level is also a negative value and moves toward zero as the deceleration increases.

The threshold level may be changed in steps according to the deceleration. In an extreme example, there may be two stages.

The control system of the present invention can be applied not only to air packs but also to seat belt control.

[Effects of the Invention] As explained above, according to the invention of claim 1, by changing the threshold level according to the deceleration, the vehicle safety device is activated quickly in the event of a severe collision to ensure the safety of the occupants. At the same time, it is possible to reliably prevent malfunction of vehicle safety devices.

According to the invention of claim 2, by changing the relationship between deceleration and threshold level according to the vehicle speed, the vehicle safety device can be activated earlier when necessary, and malfunction can be more reliably prevented. be able to.

According to the invention of claim 3, by changing the relationship between deceleration and threshold level according to the elapsed time at the time of a collision, a more accurate and faster collision can be achieved according to various impacts applied to the vehicle. This enables faster and more reliable operation of vehicle safety devices and more reliable prevention of malfunctions.

[Brief explanation of drawings]

FIG. 1 is a professional diagram showing the basic configuration of the present invention. FIG. 2 is a circuit diagram schematically showing an embodiment of the present invention, and FIG. 3 is a characteristic line diagram of deceleration-threshold voltage obtained by the circuit of FIG. 2. Fig. 4 is a circuit block diagram of another embodiment using a microcomputer, Fig. 5 is a diagram showing a map of deceleration-sureno/jord level used in the microcomputer of Fig. 4 is a flowchart showing a timer interrupt routine executed by the microcomputer shown in FIG. 4. FIG. Fig. 7 is a flowchart showing another aspect of the timer interrupt routine executed by the microcomputer, Fig. 8 is a diagram showing a map used in the routine of Fig. 7, and Fig. 9 shows the vehicle being subjected to different impacts. It is a time chart showing the deceleration of time. FIG. 10 is a flowchart showing still another aspect of the timer interrupt routine executed by the microcomputer, FIG. 11 is a diagram showing a map used in the routine of FIG. 10, and FIG.
The figure is a time chart showing changes in gain. 1 Vehicle safety device, 2, 20... acceleration detection means, 3
．． 40...integral calculation means, 4. ．． 50.113...
Collision determination means, 5.10... Drive circuit, 6,60,1
12...Deceleration compensation means, 72...Vehicle speed detection means,
T...Time measurement means, 107-111...Vehicle speed compensation means, 206-210,300...Time compensation means.

Claims (3)

[Claims] (1) A) Acceleration detection means for detecting the deceleration of the vehicle, B) Integral calculation means for integrating the deceleration from the acceleration detection means, and C) Comparing the integral value obtained by the above integral calculation means with a threshold level. (d) a drive circuit that operates the vehicle safety device based on the operation command signal from the collision determination means. A control system for a vehicle safety device comprising: a control system for a vehicle safety device, further comprising deceleration compensating means for lowering the threshold level as the deceleration increases. (2) Furthermore, a vehicle speed detecting means and a vehicle speed compensating means that lowers the threshold level as the vehicle speed increases by changing the relationship between the threshold level and deceleration in accordance with the vehicle speed from the vehicle speed detecting means. A control system for a vehicle safety device according to claim 1, comprising: a control system for a vehicle safety device according to claim 1; (3) Further, a time measuring means that starts measuring the elapsed time when the integral value reaches a predetermined level lower than the threshold level, and a time compensating means that changes the relationship between the threshold level and the deceleration according to the elapsed time. A control system for a vehicle safety device according to claim 1, comprising: