JPH0796815A - Electric controller for airbag device - Google Patents

Abstract

PURPOSE:To provide an electric controller for an airbag device with a second small auxiliary electric power supply for a trouble diagnosis circuit. CONSTITUTION:A selection connection means in which a transistor 32 is interposed between a condenser 18 serving as a first auxiliary electric power supply for an airbag expansion and a condenser 23 serving as a second auxiliary electric power supply for the expansion timing judgment of the airbag and the trouble diagnosis of an operation controller is provided. Usually, the condenser 18 is electrically connected to the condenser 23 through the transister 32 and a trouble diagnosis circuit 25b is operated for a long time through a regulater 22, even when the electric power supply from a battery 12 is cut off. After the cut off of the electric power supply from the battery 12, when the airbag is expanded by running a current to a squib 16, the expansion of the airbag is secured by making the transister 32 off through a transister 33 by the high level signal from a safing circuit 24 or an ignition judging circuit 25a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric control device for an air bag system capable of operating an air bag for a vehicle and diagnosing a failure of an operation control section of the air bag. The present invention relates to an electric control device for an airbag device having an auxiliary power source used when power supply is cut off.

[0002]

2. Description of the Related Art Conventionally, an apparatus of this type is, for example, an actual flatbed 2
No. 49772, a first auxiliary power source for storing power from a main power source and supplying power to a deployment means for deploying an air bag when the power supply from the main power source is cut off. Power to the failure diagnosis means for diagnosing the failure of the airbag operation control section and the determination means for accumulating the power from the main power supply and shutting off the power supply from the main power supply. A second auxiliary power supply for supplying power to the expansion means, the expansion determination means, and the failure diagnosis means from the main power supply due to the ignition switch being turned off, the power supply line being disconnected due to a collision, or the like. The airbag can be deployed and the failure of the airbag operation control unit can be diagnosed.

[0003]

However, in the conventional device as described above, the failure diagnosis device normally has a non-volatile memory for storing the details of the failure at the time of the failure diagnosis, and the memory compares the electric power. Since it consumes a large amount of electricity, it is necessary to store a large amount of power in the second auxiliary power source, which causes a problem that the second auxiliary power source becomes large.

The present invention has been made to solve the above problem, and its purpose is to make effective use of the electric power stored in the first auxiliary power source to reduce the size of the second auxiliary power source. An object is to provide an electric control device for the back device.

[0005]

In order to achieve the above object, the structural features of the invention according to claim 1 are the first auxiliary power source for airbag deployment and the airbag deployment timing determination. And second for diagnosing failure of airbag operation control unit
A selective connection means is provided between the auxiliary power source and the second auxiliary power source, and the first auxiliary power source is normally electrically connected to the second auxiliary power source, and the electrical connection is disconnected when the airbag is judged to be deployed. Especially.

[0006] Further, the structural feature of the invention described in claim 2 is that the timer means for measuring the elapse of a predetermined time from the interruption of the power supply from the main power source is provided, and the first means for expanding the air bag is provided. Selective connecting means is provided between the auxiliary power source 1 and the second auxiliary power source for determining the deployment timing of the airbag and for diagnosing the failure of the airbag operation control unit, and at least the power supply from the main power source is cut off. The first auxiliary power source is electrically disconnected from the second auxiliary power source from the time when the timer means finishes measuring the predetermined time.
The auxiliary power source is electrically connected to the second auxiliary power source.

[0007]

In the invention according to claim 1 configured as described above, when the airbag is not inflated after the power supply from the main power supply is cut off, the power stored in the first auxiliary power supply is selectively connected. Since it is supplied to the second auxiliary power supply via the means, the failure diagnosis means can be operated for a long time even if the second auxiliary power supply is made small. On the other hand, when the air bag is deployed after the power supply from the main power supply is cut off (even if the air bag is deployed, the power from the main power supply is cut off due to the ignition switch being turned off, the power supply line being disconnected due to a collision, etc.). It happens immediately after the power supply is cut off),
Since the electric power stored in the first auxiliary power supply is not supplied to the second auxiliary power supply through the selective connecting means and is used for expanding the airbag, the airbag can be reliably expanded. After the airbag has been deployed in this way, it is not necessary to operate the failure diagnosis means for a long time, so the function of the failure diagnosis means is not limited.

Further, in the invention according to claim 2 configured as described above, after the power supply from the main power supply is cut off, the first auxiliary power supply is provided until the timer means finishes measuring the predetermined time. Power is not supplied to the second auxiliary power supply via the selective connection means. On the other hand, even if the air bag is deployed, it occurs immediately after the power supply from the main power supply is cut off due to the ignition switch being turned off, the power supply line being disconnected due to a collision, or the like. Therefore, when the airbag is deployed after the power supply from the main power supply is cut off, the power stored in the first auxiliary power supply is supplied to the second auxiliary power supply via the selective connecting means. Since it is used for deploying the airbag without any problem, the airbag can be reliably deployed. Also in this case, the function of the failure diagnosing means is not limited because it is not necessary to operate the failure diagnosing means for a long time after the airbag has been deployed in this way. When the airbag is not deployed after the power supply from the main power supply is cut off, the failure diagnosis means is initially supplied with power only from the second auxiliary power supply, and after a predetermined time, the selective connection is established. Since the electric power from the first auxiliary power supply is also supplied via the means, the failure diagnosis means can be operated for a long time even if the second auxiliary power supply is made small.

[0009]

As can be understood from the above description of the operation,
According to the inventions according to claims 1 and 2, the second auxiliary power source can be downsized without impairing the deployment control function of the airbag and the failure diagnosis function of the operation control section of the airbag.

[0010]

【Example】

a. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an electric control device for an airbag device according to the first embodiment. This electric control device has a relatively long power supply line L through which an ignition switch 11 is interposed.
The booster 13 is connected to the battery 12 via 1. The booster 13 boosts the voltage from the battery 12 to a first predetermined voltage (for example, 12 to 16v) and supplies the boosted first predetermined voltage to the power supply line L2. A diode 14 for blocking backflow, a gate circuit 15, a squib 16 for igniting the explosive of the airbag device, and a gate circuit 17 are connected in series between the power supply line L2 and the ground. A capacitor 18 (for example, 4700 μF) forming a first auxiliary power source is connected between the connection point of the diode 14 and the gate circuit 15 and the ground.
A diode 21 and a regulator 22 are connected in series to the power supply line L2, and the regulator 22 supplies the first predetermined voltage from the power supply line L2 to the second predetermined voltage + V.
(For example, 5v) and stabilizes and outputs. Between the connection point of the diode 21 and the regulator 22 and the ground, the capacitor 2 that constitutes the second auxiliary power source
3 (for example, 9400 μF) are connected. Further, the power supply line L2 is also connected to another electric control device for the airbag device.

The regulator 22 has a second predetermined voltage + V.
A first microcomputer including the safing circuit 24, an ignition determination circuit 25a, and a failure diagnosis circuit 25b.
And a second microcomputer 25 including a non-volatile memory (E ² PROM) 25c. The safing circuit 24 integrates the acceleration input from the acceleration sensor 26 for a predetermined time by the program processing by the first microcomputer, and when the integrated value exceeds the first predetermined value, the safing circuit 24 sets the high level for a predetermined time. The safing signal is output to the gate circuit 15. The ignition determination circuit 25a integrates the acceleration input from the acceleration sensor 26 over a predetermined time by a program process by the second microcomputer 25, and the integrated value is a second predetermined value (greater than the first predetermined value). When it exceeds, it outputs to the gate circuit 17 an ignition determination signal that goes high for a predetermined time. The failure diagnosis circuit 25b is programmed by the second microcomputer 25 so that the acceleration sensor 26 itself fails, the connection wire of the sensor 26 is broken or short-circuited,
Disconnection and short circuit of connecting wire of squib 16, battery 1
The failure of the operation control unit of the air bag device such as rise and fall of the terminal voltage of the capacitor 2 and the capacitors 18, 23, disconnection and short circuit of the connection line of the warning lamp (not shown) is diagnosed every predetermined time, and non-volatile at the time of failure diagnosis. The failure content, failure time, etc. are written in the memory 25c.

One end of the capacitor 18 is connected to the emitter of a switching PNP type transistor 32 via a reverse current blocking diode 31. The collector of the transistor 32 is connected to one end of the capacitor 23. The base of the transistor 32 is an NP for switching
It is connected to the collector of the N-type transistor 33.
The emitter of the transistor 33 is grounded, and the base of the transistor 33 is connected to the output of the inverter circuit 34 to which the second predetermined voltage + V from the regulator 22 is applied. The outputs of the safing circuit 24 and the ignition determination circuit 25a are connected to the input of the inverter circuit 34 via diodes 35 and 36, respectively.

Next, the operation of the first embodiment configured as described above will be described. When the ignition switch 11 is turned on, the voltage from the battery 12 is supplied to the booster 13, and the booster 13 raises the supply voltage to the first predetermined voltage and supplies it to the power supply line L2. The first predetermined voltage of the power supply line L2 is supplied to the regulator 2 via the diode 21.
It is also supplied to the capacitors 18 and 23 via the diodes 14 and 21. Since the regulator 22 converts the first predetermined voltage into the second predetermined voltage + V and supplies the second predetermined voltage + V to the safing circuit 24, the second microcomputer 25, the inverter circuit 34, etc., the respective circuits 24, 2
5,34 are activated. The capacitors 18 and 23 are charged by the supplied voltage and store electric power.

The acceleration sensor 2 has no impact on the vehicle body.
If the acceleration detected by 6 is small, the safing circuit 24 and the ignition determination circuit 25a continue to output the low level signals to the gate circuits 15 and 17, so that the gate circuit 1
No electric current flows through the squib 16 because the elements 5 and 17 are kept off. On the other hand, when the vehicle body receives a large impact and the acceleration detected by the acceleration sensor 26 becomes very large, the safing circuit 24 and the ignition determination circuit 25a output a high level signal to the gate circuit 15 based on the integrated value of the detected acceleration. , 17 are output. As a result, the electric charge accumulated in the capacitor 18 is discharged and a large current instantaneously flows through the squib 16, so that the airbag is expanded. The discharged capacitor 18 is the first capacitor from the booster 13.
It is charged again at the specified voltage. In addition, the failure diagnosis circuit 2
Reference numeral 5b diagnoses a failure of the operation control unit of the airbag apparatus at predetermined time intervals, and at the time of failure diagnosis, writes the failure content and failure time in the non-volatile memory 25c.

In such a state, after the power supply from the battery 12 via the power supply line L1 is cut off for some reason, the power stored in the capacitor 23 is supplied to the regulator 22, and the regulator 22 is safe. Swing circuit 24, second microcomputer 2
5. Since the operation of the inverter circuit 34 and the like are ensured, the safing determination and the ignition determination are continued, and the failure diagnosis and storage are also continued. If the safing determination or the ignition determination is not made after the power is cut off, the input of the inverter circuit 34 is kept at the low level, so that the high level signal is supplied from the inverter circuit 34 to the base of the transistor 33. Therefore, in this case, the transistor 33 is turned on and the transistor 32 is turned on.
Is turned on, the power stored in the capacitor 18 is transferred to the regulator 22 and the capacitor 23 by the diode 31.
And a transistor 32. as a result,
The regulator 22 is supplied with electric power from both the capacitors 18 and 23, so that even if the capacitor 23 is downsized (the capacity of the capacitor 23 is reduced), the failure diagnosis and failure storage by the failure diagnosis circuit 25b can be performed. It keeps running for a long time.

Next, a case will be described in which the safing circuit 24 makes a safing determination and the ignition determination circuit 25a makes an ignition determination after the power supply from the battery 12 is cut off. Such a phenomenon occurs when a situation in which the airbag should be deployed due to a collision of the vehicle occurs, and at the same time as when the power supply line L1 is disconnected due to the collision. Under such circumstances, the battery 12
When the power supply from the power supply is almost cut off, the safing circuit 24
Outputs at least a safing signal, a high level signal is supplied to the input of the inverter circuit 34 via the diode 35. Therefore, at the same time that the transistor 33 is turned off, the transistor 32 is also turned off, and the power stored in the capacitor 18 is supplied to the regulator 22.
And is not supplied to the capacitor 23. In this case, when the ignition determination circuit 25a outputs the ignition determination signal, both gate circuits 15 and 17 are turned on, and a large current flows through the squib 16 due to the electric power accumulated in the capacitor 18, so that the airbag is It is definitely deployed. On the other hand, since the power stored in the capacitor 23 is supplied to the regulator 22 for a while, the failure diagnosis circuit 25b continues to operate even after the power supply from the battery 12 is cut off, and the nonvolatile memory 25c fails. The contents and the time of failure continue to be stored. After the airbag has been deployed in this way, it is not necessary to operate the failure diagnosis means for a long time, so the function of the failure diagnosis means is not limited.

B. Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows an electric control device for an airbag device according to the second embodiment. In this electric control device, the signal path from the safing circuit 24 of the first embodiment to the inverter 34 via the diode 35 and the inverter 3 from the ignition determination circuit 25 to the diode 36 are provided.
The signal path to 4 is deleted, and the power supply cutoff detection circuit 41 and the timer circuit 42 to which the second predetermined voltage + V is supplied from the regulator 22 are added. Other than that, it is the same as the first embodiment.

The power supply cutoff detection circuit 41 includes a power supply line L.
It is connected to a position near the booster 13 of No. 1 and outputs a high level signal when the input voltage has a positive value, and outputs a low level signal when the input voltage becomes zero. As a result, interruption of the power supply from the battery 12 to the booster 13 is detected. The timer circuit 42 outputs a high level signal to the inverter circuit 34 when the signal from the power supply cutoff detection circuit 41 is at a high level, starts time measurement from the time when the signal becomes a low level, and starts a predetermined short period. After the measurement of the time (for example, 103 milliseconds) is completed, the low level signal is output to the inverter circuit 34.

Also in the second embodiment constructed as described above, when the ignition switch 11 is turned on and the voltage from the battery 12 is supplied to the booster 13, the same operation as in the first embodiment is performed. To do. On the other hand, when the power supply from the battery 12 is cut off for some reason, the power supply cutoff detection circuit 41 and the timer circuit 42 are cut off.
Continues to supply the high level signal to the inverter circuit 34 for a predetermined short time after the power supply is cut off, so that the transistors 32 and 33 are turned off during the same short time. Therefore, the electric power accumulated in the capacitor 18 is not supplied to the regulator 22 and the capacitor 23 during the short time, and the air bag needs to be expanded after the power supply from the battery 12 is cut off (the above-mentioned case). As described in the first embodiment, such a situation occurs immediately after the power supply from the battery 12 is cut off).
The air bag is surely deployed by the electric power stored in the air bag. Also in the second embodiment, when the airbag is deployed as described above, the failure diagnosis circuit 25b can be operated only by the electric power stored in the capacitor 23, so the failure diagnosis is continued for a long time. It is impossible to do. However, in this case, as described above, it is not necessary to carry out the failure diagnosis continuously for a long time, so that the failure diagnosis is not hindered.

If it is not necessary to deploy the air bag after the power supply from the battery 12 is cut off, the regulator 22 is operated by the power stored in the capacitor 23 for the predetermined short time, and then Is capacitor 2
Since the operation is performed by the electric power stored in both the capacitor 3 and the capacitor 18, the operation of the failure diagnosis circuit 25b is ensured for a long time even if the capacitor 23 is downsized, and the failure of the operation control unit of the airbag device is non-volatile for a long time. It will continue to be stored in the memory 25c.

C. Third Embodiment Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows an electric control device for an airbag device according to the third embodiment. In this electric control device, the power supply cutoff detection circuit 41 and the timer circuit 42 added in the second embodiment to the first embodiment are added.

In the third embodiment constructed as described above, the safing determination circuit 24 or the ignition determination circuit 2 is used.
Since the transistor 33 is turned off by the high level signal from 5a or the high level signal from the timer circuit 42, the safing determination circuit 24 or the ignition determination circuit 2
Even if 5a generates a low level signal due to a malfunction while generating a high level signal, the electric power accumulated in the capacitor 18 will not be supplied to the regulator 22 and the capacitor 23. Further, even if the timer circuit 42 generates a low level signal by a malfunction while generating a high level signal, the electric power accumulated in the capacitor 18 will not be supplied to the regulator 22 and the capacitor 23. As a result, according to the third embodiment, the deployment of the airbag can be performed more reliably than in the first and second embodiments.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an electric control device for an airbag device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an electric control device for an airbag device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an electric control device for an airbag device according to a third embodiment of the present invention.

[Explanation of symbols]

11 ... Ignition switch, 12 ... Battery (main power supply), 13 ... Booster, 15, 17 ... Gate circuit (expansion means), 16 ... Squib (expansion means), 18 ... Capacitor (first auxiliary power supply), 22 ... Regulator, 23 ... Capacitor (second auxiliary power supply), 24 ... Safing circuit (determination means), 25a ... Ignition determination circuit (determination means), 2
5b ... Failure diagnosis circuit (failure diagnosis means), 25c ... Non-volatile memory (storage section), 26 ... Acceleration sensor, 32, 33
... transistor (selective connecting means), 34 ... inverter circuit (selective connecting means), 35,36 ... diode (selective connecting means), 41 ... power supply interruption detection circuit, 42 ... timer circuit (timer means).

Claims (2)

[Claims] 1. An airbag operation control unit having a determination unit for determining an airbag deployment timing, a deployment unit for deploying the airbag in response to the airbag deployment determination by the determination unit, and a storage unit. The failure diagnosis means for diagnosing the failure and storing the details of the failure in the same storage section at the time of the failure diagnosis, the main power supply for supplying electric power to the judging means, the expanding means and the failure diagnosis means, and the electric power from the main power supply are accumulated. Then, when the power supply from the main power supply is cut off, the first auxiliary power supply for supplying power to the expanding means and the power supply from the main power supply are accumulated to cut off the power supply from the main power supply. In an electric control device for an air bag device, which comprises a second auxiliary power supply for supplying electric power to the failure diagnosis means and the determination means, a first auxiliary power supply is normally electrically connected to a second auxiliary power supply. Allowing the above-mentioned judgment An electric control device for an air bag device, comprising: a connecting means for disconnecting the electrical connection when the fixing means determines to deploy the air bag. 2. An airbag operation control unit having a determination unit for determining the deployment timing of the airbag, a deployment unit for deploying the airbag in response to the deployment determination of the airbag by the determination unit, and a storage unit. The failure diagnosis means for diagnosing the failure and storing the details of the failure in the same storage section at the time of the failure diagnosis, the main power supply for supplying electric power to the judging means, the expanding means and the failure diagnosis means, and the electric power from the main power supply are accumulated. Then, when the power supply from the main power supply is cut off, the first auxiliary power supply for supplying power to the expanding means and the power supply from the main power supply are accumulated to cut off the power supply from the main power supply. At this time, in the electric control device for the air bag device including the second auxiliary power supply for supplying electric power to the failure diagnosing means and the judging means, a predetermined time has elapsed after the power supply from the main power supply was cut off measure When the timer means and at least the first auxiliary power supply are electrically disconnected from the second auxiliary power supply after the power supply from at least the main power supply is cut off, and the timer means finishes measuring the predetermined time. From the first auxiliary power source to the second auxiliary power source, and a selective connecting means for electrically connecting the first auxiliary power source to the second auxiliary power source.