JPH1134791A - Air bag control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air bag control device which can control many squibs even without using a CPU with a large number of terminals. SOLUTION: In an ECU 30, to one control signal output terminal of a CPU 32, a corresponding control signal input terminal in each driving IC is connected. For instance, in a control signal output terminal 42A, both a corresponding control signal input terminal 46A of the driving IC 34 and a corresponding control signal input terminal 48A of the driving IC 36 are connected. In the CPU 32, a selective signal output terminal 44A, 44B outputting a selective signal for selecting one driving IC is provided, of these terminals, from one terminal, toward the desired driving IC, a selective signal is output, only in the desired driving IC, drive control of a squib is executed. In this way, relating to the two driving ICs, necessity for providing respectively individually the control signal output terminal in the CPU 32 is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag control device, and more particularly, to an airbag control device having a plurality of airbag drive circuits for controlling the operation of a plurality of airbags.

[0002]

2. Description of the Related Art In recent years, demand for automobile airbags has been increasing. In addition, the number of airbags mounted per vehicle is increasing, not only for the driver's seat front airbag, but also for the passenger's seat front airbag and side collision airbag. Accordingly, the number of squibs to be controlled by one airbag control device has been increasing.

On the other hand, in an airbag system, it is required that the airbag operates reliably when required, and that the airbag does not malfunction when not required, so that it is possible to diagnose whether there is any abnormality in the airbag system. There is a need to. Therefore, the airbag control device is configured to be able to transmit a diagnostic signal for performing a diagnosis for each squib to be controlled, in addition to a drive signal for driving the squib to activate the airbag when the vehicle suddenly decelerates. There is a need.

When the number of squibs to be controlled by the airbag controller increases as described above, the signals to be transmitted are of two types, the drive signal and the diagnostic signal. Since the output destination increases, the signal output source CP of the airbag control device is used.
U requires a large number of terminals for outputting signals.

However, since the number of terminals of the CPU is limited, there is a possibility that a shortage of terminals of the CPU may occur.

Conventionally, in order to solve such a shortage of terminals of the CPU, a technology using a CPU for a large-scale system having a large number of terminals in an airbag control device and an IC dedicated to squib control capable of controlling a large number of squibs have been proposed. There has been proposed a technique of connecting to a CPU.

However, the CPU for a large-scale system is very expensive and large in size, and the squib control-dedicated IC becomes very expensive, including the development cost, resulting in an inconvenience of an increase in the device cost.

Therefore, as shown in FIG. 3, it is conceivable to use a plurality of squib drive ICs 90 capable of controlling about one or two squibs in accordance with the number of squibs. In this case, the large-scale system CPU and the squib control dedicated IC as described above are not required, and the cost can be avoided.

However, the CPU 92 needs a number of terminals corresponding to the number of the squib driving ICs 90. For example, in FIG. 3, two squib driving ICs
Since various control signals are transmitted to each of the signals 90 through six signal lines, the CPU 92 requires 12 (= 6 × 2) terminals.

For this reason, in an airbag system that operates a large number of airbags, it is necessary to control a large number of squibs by the airbag control device, and the number of squib drive ICs installed in the airbag control device also increases. C
Shortage of PU terminals may recur.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to solve the above-mentioned problems.
An object of the present invention is to provide an airbag control device capable of controlling a large number of squibs without using a PU.

[0012]

According to a first aspect of the present invention, there is provided an airbag control apparatus comprising: a plurality of drive circuits for outputting a drive signal for operating an airbag; Control signal output means for outputting a control signal for operation to the drive circuit; and a selection signal for selecting one drive circuit desired to be operated by the control signal among the plurality of drive circuits, to the one drive circuit A control element configured to include a selection signal output means for outputting to the control signal output means, the control signal output means using a required number of terminals to output a control signal to one drive circuit,
Outputting a control signal to all the driving circuits.

The airbag control device according to the first aspect of the present invention includes a control element and a plurality of drive circuits, wherein the control element includes a control signal output means for outputting a control signal to the drive circuit, and a selection circuit. It is configured to include a selection signal output unit that outputs a signal to one drive circuit.

Here, the control signal output means outputs the control signal to all the driving circuits by using the necessary number of terminals for outputting the control signal to one driving circuit. That is, even if there are a plurality of drive circuits, the number of terminals of the control element used for outputting the control signal by the control signal output means remains the number of terminals necessary to output the control signal to one drive circuit. As a result, the number of used terminals of the control element can be reduced.

On the other hand, the selection signal output means outputs a selection signal to one of the plurality of drive circuits to be operated by the control signal. The one drive circuit to which the selection signal is input operates according to the control signal, and outputs a drive signal for operating the airbag. On the other hand, in the other drive circuits to which the selection signal has not been input, although the control signal is input, the drive circuit is not operated by the control signal.

As described above, according to the present invention, only the appropriate driving circuit is selected and the driving circuit for operating the airbag is selected by the selected driving circuit while reducing the number of terminals of the control element for outputting the control signal. A signal can be output.

[0017]

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

FIG. 1 is a schematic configuration diagram of an airbag device 10 including an airbag control device (hereinafter referred to as an ECU) 30 according to the present invention. As shown in FIG. 1, the airbag device 10 includes a battery + terminal 1
The ignition switch 14 connected to the ignition switch 2, the safing sensor 16 connected to the ignition switch 14 and mechanically turned on when the vehicle suddenly decelerates, and connected to the safing sensor 16 via the lead wire 18. The squib resistance 22 for the inflator, the ignition transistor 24 connected to the squib resistance 22 for the inflator through the lead wire 20, the acceleration sensor 26 for detecting the acceleration of the vehicle, and the detection signal from the acceleration sensor 26, and the operation of the ignition transistor 24 An ECU 30 is provided for controlling the ECU 30. Note that the ECU 30 is connected to the base of the ignition transistor 24, the lead wire 20 is connected to the collector, and the emitter is grounded.

When the vehicle suddenly decelerates, the safing sensor 16 is mechanically turned on and the acceleration sensor 26 detects a negative acceleration. The detection signal of the negative acceleration is sent from the acceleration sensor 26 to the ECU 30. When the absolute value of the negative acceleration is equal to or more than a predetermined value, the ECU 30 determines that the vehicle has rapidly decelerated, and sends the base signal to the ignition transistor 24. Outputs current.

The ignition transistor 24 into which the base current has flowed is turned on, and as described above, the safing sensor 1
6, the closed circuit including the battery, the ignition switch 14, the safing sensor 16, the inflator squib resistor 22, and the ignition transistor 24 is formed. Will operate.

Next, the internal configuration of the ECU 30 will be described with reference to FIG. As shown in FIG.
32, squib driving ICs 34 and 36, and a current output circuit (not shown) for outputting the base current based on an instruction from the squib driving IC. FIG. 1 shows a diagram in which one squib is controlled by the ECU 30 and the basic operation as described above has been described. However, as shown in FIG. 2, the squib driving ICs 34 and 36 can control two squibs, respectively. And in fact E
The CU 30 is configured to control up to four squibs.

Six types of control signals are sent from the CPU 32 to each squib driving IC. For this reason, the CPU 32
Are provided with six control signal output terminals 42A to 42F, and each of the squib driving ICs is provided with six control signal input terminals for inputting six types of control signals. That is, the squib drive IC 34 is provided with control signal input terminals 46A to 46F, and the squib drive IC 36 is provided with control signal input terminals 48A to 48F.

Further, in the ECU 30 of the present embodiment, unlike the related art (see FIG. 3), one control signal output terminal of the CPU 32 is connected to a corresponding control signal input terminal of each squib drive IC.

For example, the control signal output terminal 42A is connected to both the control signal input terminal 46A of the squib drive IC 34 and the control signal input terminal 48A of the squib drive IC 36. That is, the signal line 50A connecting the control signal output terminal 42A and the control signal input terminal 46A branches off from the middle thereof and is also connected to the control signal input terminal 48A, whereby the control signal output terminal 42A is connected to the control signal output terminal 42A. The signal input terminal 48A is also connected.

Similarly, the control signal output terminal 42B is connected to both the control signal input terminal 46B of the squib drive IC 34 and the control signal input terminal 48B of the squib drive IC 36, and the control signal output terminal 42C is connected to the control signal output terminal 42C. Both the signal input terminal 46C and the control signal input terminal 48C are connected.

The control signal output terminal 42D is connected to both the control signal input terminal 46D and the control signal input terminal 48D, and the control signal output terminal 42E is connected to the control signal input terminal 46E and the control signal input terminal 48E. Both are connected, and the control signal output terminal 42F is connected to the control signal input terminal 4
6F and the control signal input terminal 48F are both connected.

Further, in the ECU 30 of this embodiment, the selection signal output terminals 44A, 44A, 4B, and 4C which output a selection signal for selecting one squib driving IC to the CPU 32.
4B is provided. The squib drive IC 34
Is provided with a selection signal input terminal 52A, and the selection signal input terminal 52A is connected to a selection signal output terminal 44A of the CPU 32 via a signal line 54A. Further, the squib driving IC 36 is provided with a selection signal input terminal 52B, and the selection signal input terminal 52B is connected to a selection signal output terminal 44B of the CPU 32 via a signal line 54B.

Next, the operation of the ECU 30 in this embodiment will be described. In the following, a case where the squib is driven by controlling the squib driving IC 34 will be described as an example.

The CPU 32 sends a selection signal from the selection signal output terminal 44A to the squib driving IC 34 in order to select the squib driving IC 34. CP with this
U32 outputs a control signal from the control signal output terminals 42A to 42F. As a result, the control signal is transmitted to the squib driving IC 3 via the control signal input terminals 46A to 46F.
4 is input to the squib driving IC 36 via the control signal input terminals 48A to 48F.

Accordingly, both the selection signal and the control signal are input to the squib driving IC 34, and the squib driving IC 34
36 receives only the control signal.

In the squib driving IC 34, since the selection signal is inputted, the base current is outputted from the current output circuit to the transistor 24 (see FIG. 1).
Control based on the control signal is performed.

In the squib driving IC 36, since the selection signal is not input, the input control signal is invalidated, and the control based on the control signal as described above is not performed. Is set to a high impedance state.

In this way, it is possible to control the squib driving IC 34 to drive the squib corresponding to the squib driving IC 34 while prohibiting the driving operation by the squib driving IC 36.

In the embodiment described above, the control signal output terminal of the CPU 32 is connected to the control signal input terminal of each squib driving IC corresponding to the control signal output terminal. The number is reduced than before.

For example, in FIG.
In U92, six terminals are used for each of the two squib driving ICs, so a total of 12 terminals are used. On the other hand, in this embodiment, as shown in FIG. 2, only eight terminals, six control signal output terminals and two selection signal output terminals, are used. That is, the number of terminals used is four.
One has been reduced.

On the other hand, the control signal from the CPU 32 is input to all the squib driving ICs. However, as described above, the control signal is valid only in one squib driving IC to which the selection signal is input ( Since the control for driving the squib is executed), the CPU 32 outputs a selection signal to one squib driving IC to drive the squib, so that only the one squib driving IC drives the squib. Can be executed.

Although the above embodiment has described an example in which two squib driving ICs are built in the ECU, the present invention can be applied to a case in which three or more squib driving ICs are built in the ECU. it can. Moreover, even if the number of squibs to be controlled increases and the number of squib driving ICs incorporated in the ECU increases, the number of control signal output terminals of the CPU does not change and only the selection signal output terminal needs to be newly set. Therefore, the greater the number of squib driving ICs built in the ECU, the greater the effect of reducing the number of terminals used by the CPU.

In the above embodiment, the control signal input terminal of each squib drive IC is connected to one control signal output terminal of the CPU 32 as shown in FIG.
As described above, for example, the form in which the signal line 50A connecting the control signal output terminal 42A and the control signal input terminal 46A is branched from the middle thereof and also connected to the control signal input terminal 48A has been described. A configuration in which the signal output terminal 42A and the control signal input terminal 46A and the control signal output terminal 42A and the control signal input terminal 48A are connected by separate signal lines may be employed.

[0039]

As described above, according to the present invention,
It is possible to select only an appropriate drive circuit and output a drive signal for operating the airbag by using the selected drive circuit while saving the number of terminals of the control element for outputting the control signal. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an airbag device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an ECU according to the embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a conventional ECU.

[Explanation of symbols]

Reference Signs List 10 airbag device 30 ECU (airbag control device) 32 CPU (control element) 34, 36 squib driving IC (drive circuit) 42A, 42B, 42C, 42D, 42E, 42F control signal output terminals 44A, 44B selection signal output Terminals 46A, 46B, 46C, 46D, 46E, 46F Control signal input terminals 48A, 48B, 48C, 48D, 48E, 48F Control signal input terminals 52A, 52B Selection signal input terminals

Claims (1)

[Claims] 1. A plurality of drive circuits for outputting a drive signal for operating an airbag, control signal output means for outputting a control signal for operating the drive circuit to the drive circuit, and the plurality of drives A control element configured to include a selection signal output unit that outputs a selection signal for selecting one drive circuit to be operated by the control signal from the circuits to the one drive circuit; and The signal output means outputs a control signal to all the drive circuits using a required number of terminals for outputting a control signal to one drive circuit.