JPH1081196A - Failure determining device for air bag device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly determine whether normally applied voltage and the voltage other than the normally voltage are applied or a normally supplied current and a current other than the normally current are supplied or not by applying voltage less than a designated value to a resistance or supplying a current less than a designated value. SOLUTION: Failure determination determines whether a short failure of short-circuiting in a connecting wire between a power supply wire and a scribe resistance Req occurs or not. If the output voltage V2 of an operation amplifier 16 is larger than a threshold, the squib resistance Req is in the disconnecting state so that a failure is not determined. If the output voltage V2 of the operation amplifier is less than the threshold, it is judged whether a failure of applying voltage other than the normally applied voltage is caused or not. That is, the squib resistance Rsq is not in the disconnecting state, so that the monitor voltage V1 is taken, and it is judged whether the monitor voltage V1 is larger than the threshold or not. Thus, it is determined whether the voltage other than the normally applied voltage is applied to the squib resistance Rsq or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for judging a failure of an airbag device, and more particularly, to an air judging device for judging whether or not a voltage by an applying means and a voltage other than the voltage are applied to a resistor. The present invention relates to a failure determination device for a bag device.

[0002]

2. Description of the Related Art Conventionally, an airbag device is configured such that when a vehicle suddenly decelerates, a safing sensor is turned on, an ignition transistor is turned on, and a voltage of a predetermined value or more is applied to a squib (filament) resistor. , The airbag is deployed.

By the way, in order to deploy the airbag accurately, it is necessary to determine whether the ignition transistor is normally turned on, whether the connection of the squib resistor is in a normal state, and the like. In the failure determination device of the airbag device, a voltage at which the airbag does not deploy is applied to the squib resistor, a current at which the airbag does not deploy is supplied to the squib resistor, and the above determination is made based on a voltage on the high potential side of the squib resistor. To do.

As described above, in the failure determination device of the airbag device, a voltage at which the airbag does not deploy is applied to the squib resistance. In this state, a short-circuit failure occurs in which the power supply line and the connection line of the squib resistance are short-circuited. When the vehicle is not in a sudden deceleration state, a safing sensor failure may occur in which the safing sensor is turned on. In this case, a voltage that is normally applied for making the above determination and a voltage due to these failures other than the voltage are applied to the squib resistance, so that a voltage equal to or higher than a predetermined value may be applied to the squib resistance. In this case, there is a possibility that a current equal to or more than a predetermined value is supplied to the squib resistance.

[0005] Therefore, the failure determination device for the airbag device compares the voltage on the high potential side of the squib resistance with the threshold value, and determines whether or not a voltage other than the voltage normally applied is applied. doing.

[0006]

However, in the state where the squib resistance is disconnected, the potential on the high potential side of the squib resistance becomes large. In this state, a voltage other than the voltage normally applied is applied. It is not possible to accurately determine whether or not there is.

That is, when it is determined whether or not a voltage normally applied for performing the above determination and a voltage other than the voltage are applied, if the squib resistance is disconnected, the normally applied voltage is determined. Even if no voltage other than the applied voltage is applied, it is determined that the voltage is applied.

The present invention has been made in view of the above facts, and it is intended to determine whether a normally applied voltage and a voltage other than the applied voltage are applied or a normally supplied current and a current other than the current are supplied. It is an object of the present invention to provide a failure determination device for an airbag device that can accurately determine whether the failure has occurred.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, when a voltage of a predetermined value or more is applied or a current of a predetermined value or more is supplied, a predetermined value is set to a resistance for deploying an airbag. An application supply unit that applies a voltage of less than or supplies a current of less than a predetermined value, and based on any one of a voltage of the resistor, a potential on a high potential side of the resistor, and a current flowing through the resistor, Disconnection determining means for determining whether or not the wire is disconnected; and when the disconnection determining means determines that the wire is not disconnected, the voltage of the resistor, the potential on the high potential side of the resistor, and the current flowing through the resistor. A determination unit that determines whether the voltage and the voltage other than the voltage by the application supply unit are applied to the resistor or whether the current and a current other than the current are being supplied, It has.

That is, the application supply means according to the first aspect of the invention applies a voltage of less than a predetermined value to the resistor or supplies a current of less than the predetermined value. When a voltage equal to or higher than a predetermined value is applied to this resistor or a current equal to or higher than the predetermined value is supplied, the airbag is deployed.

Here, when the resistor is disconnected, the voltage of the resistor is higher than when the resistor is not disconnected, the potential on the high potential side of the resistor is larger, and the current flowing through the resistor is smaller. Note that the case where the resistor is disconnected includes, for example, a case where the resistor is completely disconnected and a case where a part is connected.

Therefore, the voltage applied by the application supply means and a voltage other than the voltage (for example, the voltage due to the short-circuit failure or the safing sensor failure) are applied to the resistor without determining whether or not the resistor is disconnected. Or it cannot be accurately determined whether or not the current and a current other than the current are supplied.

Therefore, the disconnection determining means determines whether or not the resistor is disconnected based on one of the voltage of the resistor, the potential on the high potential side of the resistor, and the current flowing through the resistor.

When it is determined by the disconnection determining means that there is no disconnection, the determining means determines whether the voltage has been applied to the application supply means based on one of the voltage of the resistor, the potential on the high potential side of the resistor, and the current flowing through the resistor. It is determined whether the above-mentioned voltage and a voltage other than the above-mentioned voltage are applied to the resistor or whether the above-mentioned current and a current other than the above-mentioned current are supplied.

If the disconnection determining means determines that a disconnection has occurred, the above determination is not made.

As described above, when it is determined that the resistor is not disconnected, the voltage and the voltage other than the voltage are applied to the resistor by the application supply means, or the current and the current other than the current are supplied. It is determined whether or not it is, and if it is determined that the wire is disconnected, the voltage by the application supply means and a voltage other than the voltage are applied to a resistor or the current and a current other than the current are supplied. Since the resistance is not determined, a voltage other than the above-mentioned voltage is applied to the resistance by the application supply means because the resistance is disconnected, or the above-described current and the current other than the current are applied and supplied even if they are not supplied. It is possible to accurately determine whether the voltage by the application supply means and a voltage other than the voltage are applied to the resistor, or whether the current and the current other than the current are supplied. Can.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the failure determination device for an airbag device of the present embodiment has a squib resistance Rsq. When a voltage equal to or higher than a predetermined value is applied to the squib resistance Rsq or a current equal to or higher than the predetermined value is supplied, an airbag (not shown) is deployed.

One end of the squib resistor Rsq has a resistor R ₁
Are connected at one end. One end of the squib resistor Rsq is connected to one end of the safing sensor 14 and is connected to an input port P ₁ of a microcomputer 12.

[0020] Thus, since one end of the squib resistor Rsq (high potential side) is connected to an input port P ₁ of the microcomputer 12, the microcomputer 12 is a high potential side potential of the squib resistor Rsq (hereinafter, monitors the voltage it is possible to incorporate a) V ₁ that.

[0021] One end of the resistor R1 is a voltage V _B is connected to a power supply circuit (not shown) is applied. As a result, a voltage is applied to the squib resistance Rsq, but the voltage applied to the squib resistance Rsq by the power supply circuit is less than the above-described predetermined value, and the current supplied to the squib resistance Rsq is also less than the predetermined value. Airbag does not deploy.

The other end of the safing sensor 14 is connected to the high potential side of the backup capacitor C. The low potential side of the backup capacitor C is grounded. The other end of the safing sensor is connected to the above-mentioned power supply circuit (not shown) via a resistor _RC .

The other end of the squib resistor Rsq has a resistor R2
Is connected, and the other end of the resistor R2 is grounded. Further, the other end of the squib resistor Rsq, collector side of the ignition transistor T _r is connected. The base side of the ignition transistor _Tr is connected to the microcomputer 12,
Emitter side of the ignition transistor T _r is grounded.

Further, one end of the squib resistor is connected to the input terminal 16i ₁ of the operational amplifier 16, and the squib resistor R
The other end of the sq is connected to the input terminal 16i ₂ of the operational amplifier 16. Output terminal 16o of the operational amplifier 16 is connected to the input port P ₂ of the microcomputer 12. Therefore,
The microcomputer 12 may capture the output voltage from the input port P ₂ op 16 (voltage by a predetermined amplification factor times the voltage of the squib resistance).

Next, a failure determination processing routine executed by the microcomputer 12 will be described with reference to FIG. In addition,
Here, the failure determination is to determine whether or not a short-circuit failure has occurred in which the power supply line and the connection line of the squib resistor are short-circuited, as indicated by the dotted line in FIG.

In step 30 of FIG. 2, the output voltage V ₂ of the operational amplifier 16 is fetched.
_It is determined whether or not ₂ is larger than the threshold value Vth0.

Here, the threshold value Vth0 will be described. The resistance value of the squib resistance Rsq can behave as if it has increased as the squib resistance changes from a state in which the squib resistance is not disconnected to a state in which the squib resistance is disconnected. As described above, when the voltage V _B is applied from the power supply circuit to the resistor R ₁ , the squib resistor Rsq, and the resistor R ₂ , the voltage between the squib resistors increases as the squib resistor becomes disconnected, and the operational amplifier 16 output voltage V ₂ also, for example, as shown in FIG. 3, increases accordingly.

If the resistance value at which the squib resistance Rsq can be determined to be a disconnection is Rsq0, the operational amplifier 1
Output voltage V ₂ of 6 is the threshold value Vth0. That is, the output voltage V ₂ of the operational amplifier 16 is the threshold value Vth0
If it is larger, it can be determined that the resistance value of the squib resistance is larger than Rsq0, and it can be determined that the squib resistance is in a disconnected state.

The output voltage V _{2 of the} operational amplifier is equal to the threshold value Vt.
If it is greater than h0, the squib resistance is in a disconnected state, and this routine ends. That is, no failure determination is made. This is because the squib resistance Rsq is in disconnection state, also determine whether a voltage other than the voltage normally applied in this state is applied, greater than the threshold value Vth to monitor voltage V ₁ is below This is because it is determined that a voltage other than the normally applied voltage is applied even if it is not applied, and that a current other than the normally supplied current is supplied even if it is not supplied.

As described above, in the present embodiment, the squib resistance R
greater than the resistance of the sq is Rsq0, i.e., when the output voltage V ₂ of the operational amplifier is greater than the threshold Vth0, the voltage other than the voltage normally applied is applied or normal current other than the current supplied is supplied It is not determined whether or not the fault has occurred (see reference numeral E1 in FIG. 3). Therefore, since the squib resistance Rsq is disconnected, it is determined that the voltage is applied even if a voltage other than the normally applied voltage is not applied, or is supplied even if a current other than the normally supplied current is not supplied. Can be prevented.

On the other hand, when the resistance value of the squib resistance Rsq is Rs
q0 or less, that is, when the output voltage V ₂ of the operational amplifier is the threshold Vth0 below, failure voltage other than that are normally applied is applied to determine whether or not the generated (Figure 3 reference numeral E2). That is, when the output voltage V ₂ of the operational amplifier is the threshold Vth0 below, since the squib resistance Rsq is not disconnected state, at step 34, takes in the monitor voltages V _1, with stiff 36, the monitor voltage V ₁ is the threshold It is determined whether or not the value is greater than the value Vth.

Here, the threshold value Vth will be described. Monitor voltage V ₁₀ when the voltage other than that are normally applied is not applied is obtained from equation (1).

[0033]

(Equation 1)

On the other hand, when the short-circuit failure occurs and a voltage other than the normally applied voltage is applied, the resistor 3 is connected in parallel with the resistor R1 as shown in FIGS. it is conceivable that. When the combined resistance when the resistance 3 is connected in parallel to the resistor R1 and r, monitor voltage V ₁₁ when the voltage other than that are normally applied is applied it is obtained from equation (2).

[0035]

(Equation 2)

Here, r is obtained from the equation (3).

[0037]

(Equation 3)

It should be noted, because it is R1> r, is the V ₁₀ <V _11. Therefore, V ₁₀ <Vth ≦ V _11, and it is determined whether or not the monitor voltage V ₁ is larger than the threshold value Vth to determine whether a voltage other than the voltage normally applied to the squib resistance Rsq is applied. Can be determined.

If the monitor voltage V ₁ is larger than the threshold value Vth, at step 38 the flag F indicating that a short-circuit fault has occurred in which the power supply line and the connection line of the squib resistor Rsq are short-circuited is set to 1. Set and end this routine. It should be noted that the monitor voltage V ₁ is the threshold value Vt
If not more than h, this routine ends.

In the above-described embodiment, whether or not the squib resistance is in a disconnected state is determined based on the output voltage of the operational amplifier. However, the present invention is not limited to this. The determination may be made based on this.

In the embodiment described above, the output voltage V ₂ is compared with a constant threshold value Vth0 in order to determine the disconnection of the squib resistance (see FIG. 2, step 32). The present invention is not limited to this,
The monitor voltage V ₁ may be taken in, and the output voltage V ₂ may be compared with a threshold th · V ₁ determined by the monitor voltage V ₁ .

That is, R ₂ ≫Rsq, and R ₂ + Rs ≒
R ₂ . Also, the current i flowing through the squib resistance Rsq
Is i = V ₁ / R _2, the voltage Vsq squib resistor Rsq is _{Vsq = (Rsq / R 2)} · V 1.

Therefore, the output voltage V ₂ is obtained from the equation (4), where G is the amplification degree of the operational amplifier.

[0044]

(Equation 4)

Rsq = Rsq0 and G · (Rsq0
/ R ₂ ) = th, the threshold value th · V ₁ is obtained.

As described above, the monitor voltage V ₁ is acquired,
The determination of the disconnection of the squib resistance by comparing the output voltage V ₂ with the threshold value th · V ₁ determined by the monitor voltage V ₁ is based on the variation in the resistance values of the resistors R ₁ and R ₂ and the voltage applied from the power supply circuit. This is because the variation in the applied voltage was considered. That is, since these variations the output voltage V ₂ varies, it may not be possible to determine the disconnection of accurately squib resistor Rsq be compared with a threshold value Vth0 constant value.

On the other hand, if the squib resistance Rsq is not disconnected, for example, even if the monitor voltage V ₁ rises due to the above-described variation, the output voltage V ₂ will remain at the monitor voltage V
Because increases in proportion to ₁ increase, the output voltage V ₂ does not exceed the threshold th · V _1. However, when the squib resistor Rsq is broken, not proportional to the increase in the monitor voltage V _1, the output voltage V _2, in order to increase greater than increase of the monitor voltage V _1, the output voltage V ₂ is the threshold th・
More than V _1.

[0048] Therefore, when it is judged uptake monitor voltage V _1, the disconnection of the squib resistor Rsq by comparing the output voltage V ₂ and the threshold th · V _1, the voltage applied from the power supply circuit, the resistor R _1, even if the resistance value, monitors the voltage V ₁ of the R ₂ are varied can be determined disconnection accurately squib resistor Rsq.

In the above-described embodiment, whether or not the short-circuit fault has occurred is determined based on the monitor voltage. However, the present invention is not limited to this, and the output voltage of the operational amplifier or the squib resistance May be determined based on the current flowing through the power supply.

In the above-described embodiment, when the above-mentioned determination is made based on the current flowing through the squib resistor, a shunt resistor may be further provided to take in the current flowing through the squib resistor via the shunt resistor. Good.

Further, in the above-described embodiment, an example will be described in which a short-circuit fault occurs in which the power supply line and the connection line of the squib resistor Rsq are short-circuited and a voltage other than the normally applied voltage is applied. However, the present invention is not limited to this, and can be similarly applied when determining the failure of the safing sensor.

[0052]

As described above, according to the present invention, even if a voltage other than the above-mentioned voltage is applied to the resistance by the application supply means because the resistance is disconnected, or if a current other than the above-mentioned current is not supplied, the present invention is applied. It can be prevented from being determined that the voltage has been applied, and it is accurately determined whether the voltage and a voltage other than the voltage by the application supply unit are applied to a resistor or whether the current and a current other than the current are supplied. Since the determination can be made, there is an effect that the reliability of the failure determination device for the airbag device can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of the present embodiment.

FIG. 2 is a flowchart illustrating a control routine according to the embodiment.

FIG. 3 is a graph showing an area for determining a short-circuit failure.

FIG. 4 is a conceptual diagram of a connection state of a resistor when a short-circuit fault occurs.

[Explanation of symbols]

Rsq squib resistance _Tr ignition transistor R2 resistance 12 microcomputer

Claims (1)

[Claims] When a voltage equal to or higher than a predetermined value is applied or a current equal to or higher than a predetermined value is supplied, a voltage lower than a predetermined value is applied to a resistor for deploying the airbag or a current lower than the predetermined value is applied. Disconnection determining means for determining whether or not the resistor is disconnected, based on one of a voltage of the resistor, a potential on the high potential side of the resistor, and a current flowing through the resistor; When it is determined by the means that there is no disconnection, the voltage and the voltage by the application supply means are determined based on one of the voltage of the resistor, the potential on the high potential side of the resistor, and the current flowing through the resistor. A determination unit for determining whether a voltage other than the above is applied to the resistor or whether the current and a current other than the current are supplied.