JPH04133839A - Control system for vehicle safety device - Google Patents

Abstract

PURPOSE:To increase the reliability of a vehicle safety device by constituting the device so that the start-prohibited condition of it is effectively prevented from being immediately released even if the added result shows the normal condition, where trouble of the acceleration sensor is detected according to the added result of a pair of output signals. CONSTITUTION:A vehicle safety device 1 is provided with a control unit 3 for controlling the operation of an air bag apparatus 2. The control unit 3 judges the production of collision of a vehicle by means of a 1st judging unit 5 and a 2nd judging unit 7 according to a pair of acceleration signals Sa and Sb from an acceleration sensor 4. Namely, when the judgment of collision is made by means of the judgment units 5 and 7, current flows from a battery 10 to a squib 8 to expand the air bag apparatus 2. Also, a signal from the acceleration sensor 4 is monitored by a monitor circuit 9 to check whether it is normal or not and, if it is not normal, a level of the output cable 9a is made to around the ground potential. A voltage signal must also be applied to the judgment units 5 and 7 by a voltage application circuit 100 to prohibit the collision judgment operation.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention... The present invention relates to a control system for a vehicle safety device that operates a vehicle safety device such as an air pack or a seat-held restraint device in the event of a vehicle collision to ensure the safety of occupants.

(Prior Art) In this type of conventional system, an acceleration sensor detects the acceleration that occurs in a vehicle at the time of a collision, and the occurrence of sudden deceleration of the vehicle at the time of the collision is detected based on the integral value of the output from this sensor. It is configured to detect this and activate the necessary safety devices. In such a system. When a predetermined deceleration state occurs due to a vehicle collision, it is required to have high reliability by reliably detecting this and activating the safety device and preventing malfunctions due to noise or the like.

This type of control system that can satisfy these requirements uses an acceleration signal generator that outputs a pair of acceleration signals that are in opposite phases to each other, and differentially amplifies the pair of acceleration signals. In addition to removing noise components input in the same phase and determining vehicle collisions with high reliability, we focused on the fact that the sum of a pair of acceleration signals is always zero under normal conditions, and added the pair of acceleration signals. The present applicant has proposed a control system that prevents malfunctions in the event of a fault by prohibiting activation of a safety device when the result is other than zero.

(Problem to be solved by the invention) However. There are various states of acceleration that occur in a vehicle, and in this proposed control system, even if there is a problem with the sensor, the result of adding a pair of acceleration signals becomes zero, or for some other reason. If this occurs, there is a problem in that even if there is a malfunction in the sensor, the above-mentioned prohibition function will be temporarily canceled under special conditions, causing the safety device to malfunction.

It is therefore an object of the invention to provide a more reliable control system for vehicle safety equipment.

(Means for Solving the Problems) A feature of the present invention for achieving the above object is a control system for detecting a collision of a vehicle and activating a vehicle safety device. sensor means for outputting a pair of acceleration signals of mutually opposite phases in response to the acceleration of the vehicle; and differential calculation means for performing differential calculation based on the pair of acceleration signals; determining means for determining a collision of a vehicle; monitoring means for responding to the sensor means and monitoring whether the sum of the pair of acceleration signals is within a predetermined level range; The present invention further comprises voltage applying means for applying a bias voltage to the determination circuit means to prevent the vehicle safety device from being activated when the value falls outside the predetermined level range.

(Function) If the sum of the pair of acceleration signals is within a predetermined level range, the determining means performs a predetermined determining operation without being influenced by the voltage applying means. On the other hand, if the monitoring means detects that the sum of the pair of acceleration signals is outside the predetermined level range, the monitoring means responds to this and sends a signal to a required location in the determination circuit means. A bias voltage is applied by the voltage application means to prevent activation of the vehicle safety device.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Figure 1 is. 1 is a circuit diagram showing an embodiment of a control system according to the present invention for controlling a vehicle safety device; FIG.

The vehicle safety system 1 shown in FIG. It is configured as a control system for controlling the operation of the air pack device 2, which is a vehicle safety device, and when a vehicle (not shown) to which the air pack device 2 is attached collides, this is detected and the air pack device is activated. 2.

The control unit 3. In order to detect the acceleration of a vehicle (not shown), an acceleration sensor 4 having a pair of output terminals 4a and 4b is provided, and a first acceleration signal Sa having a level corresponding to the acceleration of the vehicle is output from the output terminal 4a. The other output terminal 4b outputs a second acceleration signal sb which has the same absolute value level as the first acceleration signal Sa but has an opposite phase.

As shown in FIG. 2, the acceleration sensor 4 includes piezo elements 41, 42 . and resistors 43 to 46 are connected as shown in the figure, and the power supply voltage Vc is connected to the common connection point
A bias voltage vb divided by 6 is provided.

In this embodiment, Vb is set to 1/2Vc.

The piezo elements 41, 42 are attached to a common base plate 47 (base member), as shown in FIG. This base plate 47 is made of a rigid body and is fixed at an appropriate location perpendicular to the traveling direction A of the vehicle, and the piezo element 41
．． 42 is. It generates voltage by receiving tensile and compressive forces as the vehicle accelerates and decelerates.

As a result, the other terminals of the piezo elements 41 and 42 have
A voltage is generated by adding voltage signal components corresponding to acceleration and deceleration to the bias voltage vb, and these voltages are the first
The acceleration signal Sa and the second acceleration signal sb are outputted from the output terminals 4a and 4b, respectively.

Here, since the piezo elements 41 and 42 receive equal inertial force during acceleration and deceleration of the vehicle, they output synchronized signal components. In particular, in this embodiment, since the piezo elements 41 and 42 are fixed to a common base plate 47. The shock and vibration caused by a vehicle collision are simultaneously transmitted to the piezo elements 41 and 42 via the base plate 47, thereby making it possible to synchronize each voltage signal component generated in response to the shock with high precision.

Piezo element 41. ．． 42 are connected in different directions, their output voltage signal components are in opposite phase with respect to the bias voltage vb. In detail,
When the acceleration is zero, both acceleration signals Sa and Sb are maintained at the bias voltage vb. In the case of negative acceleration, that is, deceleration caused by a collision, etc., as shown in FIG. 4, the level of the first acceleration signal Sa or the bias voltage vb
As a result, the level of the second acceleration signal sb becomes higher than the bias voltage vb.

The absolute values of the differences between the voltages of these signals and the bias voltage vb, in other words, the absolute values of the signal components associated with the deceleration, are both ΔV because the characteristics of the piezo elements 41 and 42 are the same. Therefore, the values of each acceleration signal are as follows.

5a=-ΔV+Vb-=+11sb=Δ
V+Vb.=+21 In the acceleration state, contrary to the above, the first acceleration signal Sa becomes higher than the bias voltage vb, and the second acceleration signal sb becomes lower than the bias voltage vb.

Returning to FIG. 1, the control unit 3 further controls the first determination unit 5 and the second determination unit 7 in order to determine the occurrence of a vehicle collision based on the pair of acceleration signals Sa and Sb from the acceleration sensor 4. We are prepared.

The first determination section 5 includes a differential amplifier circuit 51 configured to obtain an output corresponding to the difference between the first acceleration signal Sa and the second acceleration signal sb.

The differential amplifier circuit 51 includes a differential amplifier 52 and resistors 53 to 56 connected as shown in the figure, and receives a first acceleration signal S.
A is applied to one input terminal of the differential amplifier 52 via a resistor 55, and a second acceleration signal Sb is applied to its input terminal via a resistor 53.

Here, the differential amplifier circuit 51 is configured such that when an arbitrary signal is inputted in the same phase, no change occurs in its output.
In response to the acceleration signals Sa and Sb, a first differential output voltage DSI according to the difference between them is outputted from the differential amplifier circuit 51 and inputted to the integrating circuit S8.

The integrating circuit 58 applies a predetermined offset voltage V to the 1,000-volt terminal.
FI is an integrating circuit with a known configuration consisting of an operational amplifier 60 supplied by a power source 59, a capacitor 61, and a resistor 62, and integrates the first differential output voltage DS1,
The integrated output voltage Gl obtained as a result, the voltage comparator 63
is applied to one input terminal of

A reference voltage VR1 is supplied to the input terminal of the voltage comparator 63 by a voltage source 64 via a resistor 67, and G
When l<VRI, the output level of the voltage comparator 63 becomes a high level state, and the transistor 66, which is applied to the power supply voltage Vc or the resistor 65 through the resistor 65, turns on, and its collector potential becomes approximately ground potential. becomes. code 6
8 is a constant voltage diode for applying a bias voltage to the emitter of the transistor 66.

I want to. When the vehicle is decelerated due to a collision, the level of the first differential output voltage DSL increases, and the level of the integral output voltage G1 decreases accordingly, so that Gl<VRI.
When this happens, the transistor 66 turns on. That is, the configuration is such that it is determined that a vehicle collision has occurred when G 1 <VRl.

Next, the second determination section 7 will be explained. The second determination unit 7 includes a differential amplifier circuit 7 configured to obtain an output according to the difference between the first acceleration signal Sa and the second acceleration signal sb.
1. The differential amplifier circuit 71 includes a differential amplifier 72
and resistors 73 to 76 are connected as shown,
The first acceleration signal Sa is connected to the differential amplifier 7 via the resistor 73.
The second acceleration signal sb is applied to the + input terminal of No. 2, and the second acceleration signal sb is applied to its one input terminal via the resistor 75.

Here, the differential amplifier circuit 71 also has a configuration in which the output does not change when an arbitrary signal is inputted in the same phase. The second signal responds to the signals Sa and Sb and follows the difference between them.
A differential output voltage DS2 is output from the differential amplifier circuit 71,
The signal is input to an integrating circuit 78. Therefore, as can be understood from Figure 4, if a collision causes a sudden deceleration of the vehicle,
The potential at the 10 input terminal of the differential amplifier 72 increases in the negative direction, and the potential at the - input terminal increases in the positive direction.
In this case, the level of the second differential output voltage DS2 changes in a decreasing direction.

The integrating circuit 78 applies a predetermined offset voltage V to the ten input terminals.
This is an integrating circuit of a known configuration consisting of an operational amplifier 80, a capacitor 81, and a resistor 82, which is supplied by the F2 power supply 79, and integrates the second differential output voltage DS2.
The integrated output voltage G2 obtained as a result is applied to the 1,000-power terminal of the voltage comparator 83.

One input terminal of the voltage comparator 83, to which the power supply voltage Vc is applied via the resistor 85, is connected to the reference voltage VR.
2 is supplied from a voltage source 84 through a resistor 86, and when G2>VH2, the output level of the voltage comparator 83 becomes a high level state.

I want to. When the vehicle decelerates due to a collision, the level of the second differential output voltage DS2 decreases, and the level of the integrated output voltage G2 increases accordingly, and when G2>VH2, the output of the voltage comparator 83 or become a high level state. In other words, the configuration is such that it is determined that a vehicle collision has occurred when G2>VH2.

One end of the squib 8, which is the ignition element of the air pack device 2, is connected to the positive electrode of the battery 10 via a transistor 9 whose conduction is controlled according to the output from the first determination section 5. The end is connected to the negative electrode of the battery 10 via another transistor 11 whose conduction is controlled according to the output of the second determination section 7 .

Therefore, when the collision is determined in the first determination section 5, the transistor 9 is made conductive, and at the same time, when the collision is determined in the second determination section 7, the transistor 11 is rendered conductive. In this case, a current necessary for ignition flows from the battery 10 to the squib 8, and the air pack device 2 is deployed.

The vehicle safety system 1 further includes a monitoring circuit 9 for monitoring whether the signal from the acceleration sensor 4 is normal or not.
It is equipped with The monitoring circuit 9 responds to the first and second acceleration signals Sa and Sb by utilizing the fact that if the first and second acceleration signals Sa and Sb are normal, they are always in an opposite phase relationship.
It is configured to determine whether the absolute value of the addition result is below a predetermined level. As a result of this level check, if it is determined that the input signal from the acceleration sensor 4 is normal, the level of the output line 9a will be approximately the power supply voltage +
Vc, but if it is determined that the input signal from the acceleration sensor 4 is abnormal, the level of the output line 9a becomes approximately the ground potential.

A concrete circuit diagram of the monitoring circuit 9 is shown in FIG. The monitoring circuit 9 includes an adder circuit 91, a window comparator circuit 94 consisting of two voltage comparators 92 and 93,
It has a threshold voltage generation circuit 95.

The adder circuit 91 consists of two resistors 91a and 91b, and the first and second acceleration signals Sa and Sb are applied to these resistors 91a and 91b, respectively. I wanted to,
The additional voltage VAD generated at the connection point Y of these resistors 91a and 91b is VAD=(Sa+5b)Xi/2
-(31) This added voltage VAD is supplied to one input terminal of the voltage comparator 92 and the ten input terminals of the other voltage comparator 93.

The threshold voltage generation circuit 95 is made up of resistors 95a to 95c connected in series, one end of which is supplied with the power supply voltage Vc, and the other end of which is grounded. These resistors 95a, 9
5b and 95c divide the voltage Vc into two voltages or the threshold voltage T1. T2 (1, -) is applied to the →- manual terminal of the voltage comparator 92 and one input terminal of the voltage comparator 93, respectively.

As shown in FIG.
, IETl, T: 11, bar ry:z, voltage V'
The threshold voltage T of ζ1, is set so that from L) to X' is equal to b.
1 is higher than pi i″sI:1−vb<3 V
b, is set lower than % 2, and the other Threso 1
The default voltage T2 is set to be lower than the input voltage %, r, and higher than vb, .2.

Next, the operation of the monitoring circuit 9 configured as described above will be explained. Acceleration SE: 2 and 4 are operating normally] 5, then the first and second. Acceleration and deceleration #1 in acceleration signal 5aSb. One corresponding negative component cancels out, and the added voltage V A D becomes equal to Via 7 @ I'f V b. This is clear by substituting formula (1) and formula (2) into formula (3).
Therefore, in this case, the additional voltage VAi) is equal to S1, .
・Njord voltage T1. ``The voltage between r2 is 1, and the output level of the wind control circuit 9.4 is 1, that is, the output line 9a0) level is approximately 1, and the source voltage +-Vc It is.

Next (,, if the output is zero V or ill yaw Ve-) due to disconnection or show of the acceleration sensor 1, etc.), proceed. 7 First, we will discuss the case where one of the outputs from the acceleration sensor 4 outputs IE1]・~゛C due to a failure.
゛ is Vb/2 -) Therefore, the additional 1M pressure V A
D is 81 V b , /' 2 (l: na-y T:
The output line 9a of the window, co/valley and evening circuits 94 is at a low level of 1.
,・1 becomes bell state, and others are normal: ',',!
If the acceleration signal of i′ is acceleration or deceleration l:”, then t
, Shi Helltona ~), the 9th F also has an additional power BVAD.
In order to make the threshold voltage 'r 1' 8 times, the threshold [IIET'l is 3, , / 2
...V'))) (relatively low L...set to 1.1).

Next, let us describe the case where the output from the acceleration sensor 4 is 7, and the output L/bevel is zero. When the acceleration is full, the level of the normal signal from the other main circuit is V b /'2, so the added voltage νAD also becomes V h , . As a result, the output of the light output circuit 94 becomes low level.

In addition, if the acceleration signal of a normal external force, acceleration or decrease, speed f
If, +:, even if the level of 5 changes and is 1, is the added voltage V A D -1 - 1...? In order to increase the threshold voltage T2 by one rotation to ), the threshold voltage T2 is set at a relatively high value of 1 N, apart from )1b,...'1)6. In this way, the monitoring circuit 9 is the sum of the first and first !acceleration signals Sa and Sb to determine whether the acceleration sensors 5 and 4 are operating normally. Second, if there is a problem, When the level of this output line 9a is 1. Bell 4. is set to approximately ground potential 3. When the level of the output line 9a is at approximately ground level, the first judgment unit 5 and the second judgment unit 7 are set to 7. Therefore, a voltage application circuit loo for sending a voltage signal for prohibiting collision judgment operation to each judgment section is provided to prevent a vehicle collision from being judged. :There is.

Voltage i1j adding circuit i o o d, 101=10
7 is a diode, 108・-i i 3 is a resistor 511
4111), the transisister 7116 has a capacitor 7' for noise removal.The potential of the output line 9a is approximately equal to the power supply voltage.
4 are reverse biased (e), (so that each anode of these diodes 101--104 is
(at the 11th position of the point -) vs. j7.''ζ electric voltage application circuit 1i) Oi;
1. Unjis ytz, tis are in a non-conducting state at the time of 7. Similarly, there is C.

1. The level of the output line 9a of the key 1 is approximately ground/bell a) The die 5 and the leads 101 to 104 are in the forward bar/1' as-like state, and the →-input terminal of the differential amplifier 52 is The potential of A is fixed by the divided voltage 1ζ generated by the resistor 54. The potential of the input terminal A' is always kept lower than the potential of that one input terminal, . At the same time,
Since one input terminal of the operational amplifier 60 constituting the integrating circuit 58 is grounded via the diode 103 and the resistor 111, the value of the integrated output voltage Gl of the integrating circuit 58 will rise rapidly. Then, since the transistor 114 is turned on, the output of the voltage comparator 63 is reliably at a low level. As a result, transistor 66 is clamped to the off state, and transistor 9 therefore
It is reliably kept in the off state regardless of the output state.

In exactly the same manner, the second determination section 7 is brought into operation to ensure that the transistor 11 is kept in the OFF state regardless of the output state of the acceleration sensor 4.

This system 1 further sets the output line 5a of the first determination section 5 to a high level and the output line 7a of the second determination section 7 to a low level state for a predetermined period of time when the power of the system 1 is turned on, A delay control circuit 120 for keeping each transistor 911 in an off state is incorporated in the voltage application circuit 100.

The delay control circuit 120 includes a voltage comparator 121 to which a reference voltage vb is applied to the negative input terminal, a capacitor 122, a transistor 123, and a resistor 124125, which are connected as shown.

In the delay control circuit 120, when the voltage element VC is applied by turning on the power, the terminal voltage of the capacitor 122, that is, the potential of the input terminal of the voltage comparator 121 increases according to a time constant determined by the resistor 124 and the capacitor 122. However, after a predetermined period of time has elapsed, the potential of the input/output terminal becomes greater than the potential of one input terminal. Therefore, immediately after the power is turned on, the level of the output line 121a of the voltage comparator 121 is approximately the ground level, and the diodes 106 and 107 are in a forward bias state, clamping the transistor 66 of the first determination unit 5 in the off state, and outputting The level of the line 5a is maintained at a high level, and the level of the output line 7a of the second determination section 7 is maintained at approximately the ground level. After a predetermined period of time has elapsed after the power was turned on, voltage comparator 1
When the level of the output line 12ta of 21 becomes a high level state, both the diodes 106 and 107 become reverse biased, and each determination section 5 and 7 operates as described above without being affected by the delay control circuit 120. can be done.

Note that due to the function of the diode 105, the voltage comparator 12
Even if the level of the output line 121a of No. 1 changes, the operation of the voltage application circuit 10 described above is not affected by this change. The capacitor 116 determines the delay time when the output stage circuit of each control section 5.7 is released by the above-described control operation of the delay control circuit 120.

The base of the transistor 123 is connected to the output line 9a of the monitoring circuit 9 via the resistor 125, so when the level of the output line 9a becomes low due to a failure of the acceleration sensor 4, the transistor 123 turns on and the capacitor 1
22 is discharged, the level of the output line 121a of the voltage comparator 121 becomes a low level, and the transistors 9 and 11 are kept off for the reason mentioned above.

As is clear from the above explanation. Vehicle safety system
When the power is turned on, the delay control circuit 120 included in the voltage application circuit 100 forcibly turns off the transistors 9 and 11 for a predetermined period of time. and second determination section 5.7
Even if the operation of the squib 8 becomes unstable, the squib 8 will not be ignited. Here, if the acceleration sensor 4 is operating normally, the level of the output line 9a of the monitoring circuit 9 is maintained at a high level, and the first and second determination units 5 and 7 are connected to the voltage application circuit 100. Perform the desired action without consequences.

When a failure occurs in the acceleration sensor 4, the output line 9 of the monitoring circuit 9
The level of a becomes a low level, and the first and second determination units 5.
Various bias voltages are applied to each part of the air pack device 7 to prevent deployment of the air pack device 2, and no matter how the output of the acceleration sensor 4 changes, the transistors 9 and 11 are kept in the off state, and at the same time, the delay control circuit 120 output lines 120
The level of a is also set to a low level state.

Did you? Under special conditions, acceleration 1':
゛・S4 or failure (despite the output line 9 ia's 1...＼5 or temporarily high L・△・、1 failed.
1. Also, the integral output of Ij′l′i′: is:
=i, so that no collision occurs within the period of the temporal change. Furthermore, the delay control circuit I II! +'1 l:Yo] However, for a predetermined period of time, transistors 9 and 11 are kept in the forced lX off state. , 1 Ill? - It's an expensive novel at night.) But 7. ,,by 1',
f''c.../J/Reliably prevents device 2 from malfunctioning.)i',',',',',, +!',',' or
6. Furthermore, as can be seen from the explanation L, the manner of application of the bias voltage applied to each part of the first and second judgment parts [j, 7] in response to the level change of the output line 9a is the same as that of the actual game. +・, limited to the example i゛, output line 9a temporarily (, even if it returns to the high level, the tote ... Raster 9.], !, purpose of preventing the 4-on from turning 7) It is clear that changes can be made as appropriate within the range of 1. (Effects of the Invention) According to the present invention, as stated in L, acceleration!1i!'
The result of addition of the failure detection signal A and the output signal of the pair M (
, base) ii (“Go to line, jM4, some cause ζ゛i,”
Is it the addition result or normal condition? (”-LL.11.゛na2
．． But 11, this effectively prevents it from being canceled by East + M ゛.
(It is possible to provide a control system with high R conversion.)

[Brief explanation of the drawing]

Figure 1 shows the safety system for vehicles according to Jj-all numbers:
Figure 2 shows the circuit diagram of the acceleration sensor in Figure 1. Soft 4 diagram φ diagram, Figure 4 shows an example of the wave radiation of the output signal of acceleration
Circuit diagram of the d-monitoring circuit shown in figure 1. Figure 6 explains the operation of the monitoring circuit in 1) for 4a).・Bell diagram? ``There is one, one...
・Vehicle safety system 7: Sea...air hack device, :]...control unit, 4...
・Acceleration sensor, 4a, 4b...output terminal, :)...
・First judgment section, 7... Second judgment section, 8... Squib, 9.11... Transistor, 10... Bar.
Soteri, 51.71...Differential amplifier circuit, ioo...
[Cat application circuit, Sa...first acceleration signal, b second acceleration signal, 1) St D S 2...differential output voltage 1, Fig. 2

Claims (1)

[Claims] 1. A control system for detecting a vehicle collision and activating a vehicle safety device, comprising: a sensor means for outputting a pair of acceleration signals having opposite phases to each other according to the acceleration of the vehicle; determining means for determining a collision of a vehicle based on the result of the differential calculation, including differential calculation means for performing differential calculation; and determining means for determining a vehicle collision based on the result of the differential calculation; monitoring means for monitoring whether or not the vehicle safety device is within the predetermined level range; 1. A control system for a vehicle safety device, comprising: a voltage application means for applying a bias voltage to make the vehicle safety device.