JPH0621795Y2 - Air bag device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is based on an airbag having cushioning properties such that the front of the vehicle collides with something and the driver receives a shock such as hitting his face on the steering wheel. The present invention relates to an air bag device for reducing and protecting a driver.

[Conventional technology]

The airbag device is generally constructed as shown in FIG.
In the figure, a vehicle G has four G sensors 1 _1L , 1 _1R , 1 which respond to a predetermined external force applied when a frontal impact is applied.
_21, and 1 _22, an inflator (nitrogen generator) 3 housed in the central portion of the handle D, and air bag 4 for absorbing shocks to the face directly the diagnostic unit 5 for diagnosing the state of each functional parts Is equipped with. G sensor 1 _{1L to} 1
_Reference numeral ₂₂ denotes front sensors 1 _1R , 1 _1L attached to the left and right in front of the front side frame, and two cowl sensors 1 ₂₁ 1 attached to the diagnostic unit 5 installed in the room in front of the center tunnel. ₂₂ and includes a predetermined external force (for example, the front sensor 1) due to the impact of the vehicle.
_1R , 1 _1L is 12.3G or more, the cowl sensor 1 ₂₁ ,
1 ₂₂ is configured to close the built-in contact by more than 2.3G).

The diagnostic unit 5 is installed in a room in front of the center tunnel on the floor surface of the vehicle body and constantly diagnoses whether or not there is an abnormality in the entire system. In addition, it has a function that can cope with power failure and voltage drop.

The warning light 11 is built in the meter panel and lights up at the same time when the diagnostic unit detects an abnormality in the system to notify the driver. Further diagnostic unit 5
It detects the state of the G sensor 1 _1L to 1 ₂₂ within the control circuit for controlling the inflator 3 and is built, and each G sensor and the control circuit are connected by a wire harness W / H.

A series of operations of such an airbag device will be described below.

When a collision from the front occurs, the front sensor 1 _1L ,
When 1 _1R and the cowl sensor _{1 21, 1} by at least one ₂₂ operates by sensing a predetermined or more impact at the same time,
An electric signal is sent to the electric ignition device of the inflator 3.

An electric signal is sent to the heater in the electric igniter to heat the heater and ignite the nitrogen gas generating agent (sodium nitride).

A large amount of nitrogen gas is generated by this combustion, and the gas is sent into the airbag 4.

The airbag 4, which is bulged out by the nitrogen gas, swells by breaking the cut of the urethane cover in the center of the handle. An air bag inflated with nitrogen gas catches the driver's face, and then it is installed on the back of the bag. 2
By releasing nitrogen gas from each discharge hole, the impact on the driver's face is mitigated.

Since this airbag device is a device for reducing driver's injury, extremely high reliability is required. Since the airbag 4 is normally folded in a small size and is structured to be deployed as needed, it is important to eliminate the risk of malfunction that opens when not needed and that it does not open when needed. Therefore, the idea of fail-self has been introduced.

The airbag device described above is electrically configured as shown in FIG. In FIG, CPU 7 is provided in the control circuit 2, and the wire harness W / H to contact SW ₁ is pulled up to the battery voltage + B of the G sensor _{1 1L} to _{1 22} (collectively referred to by reference numeral 1 below) It is connected via a buffer 8 for waveform shaping. In addition, accessories (A
The CC) power supply and the ignition (IG) power supply are input to the control circuit 2 via the fuses of the junction boxes J and B, and the ACC power supply is stabilized through the constant voltage circuit 6 and supplied to the CPU 7 as a drive voltage. A backup capacitor C ₁ is connected to the input of the constant voltage circuit 6. In addition, the ACC and IG power supplies are diodes D ₁ and D
_It is connected to the emitter of the drive transistor Q ₁ via ₂ and its base voltage is controlled by the CPU 7. The collector is also connected to the inflator 3. Further, the IG power supply is connected in series with a lamp L ₁ provided in the warning lamp 11 for indicating a power supply voltage drop and a transistor Q ₂ provided in the control circuit 2, and the base voltage thereof is controlled by the CPU 7.

In the above configuration, in the normal state, the contact SW ₁ of the G sensor ₁ is off, and + B is applied to the CPU 7. The CPU 7 detects this state and turns off the drive transistor Q ₁ . As a result, the inflator 3 is not energized and is in a non-explosive state. If the battery voltage is normal, the CPU 7 turns off the transistor Q ₂ and turns off the lamp L ₁ .

On the other hand, when the front of the vehicle C collides, the G sensor 1
When a predetermined external force is applied to the contact SW _{1 of} at least one G sensor is turned on. Therefore, the line of the wire harness W / H connected to the G sensor 1 of the CPU 7 becomes the ground potential. In this state CPU7 turns on the driving transistor _{Q 1,} energizing inflator 3 and the lamp _{L 1.} When the inflator 3 is energized, the nitrogen gas generating agent burns (explodes) by ignition as described above, and the generated nitrogen gas is sent to the airbag 4. When the battery voltage drops, the CPU 7 detects this and turns on the transistor Q ₂ to turn on the lamp L ₁ . The buffer 8 is provided for shaping the output from the G sensor 1 and inputting it to the CPU 7.

[Problems to be solved by the invention]

In the above configuration, if the wire harness W / H is broken or short-circuited for some reason, the input level of the CPU 7 is set even though the vehicle C is in a normal state and the contact SW ₁ of the G sensor ₁ is off. Becomes the ground potential to turn on the transistor Q ₁ to energize the inflator 3, or the contact SW ₁ is turned on at the time of collision, but the input line of the CPU 7 becomes the battery voltage and the transistor Q ₁ is turned off. And keep the inflator 3 unenergized. Therefore, inflator 3
Causes a malfunction such as non-explosion or erroneous explosion, resulting in a significant decrease in reliability.

Therefore, the present invention is intended to provide an airbag device capable of distinguishing a wire harness disconnection or short circuit from the state of the G sensor.

[Means for solving problems]

The present invention has been made in view of the above problems, and a G sensor having a contact point that responds to a predetermined external force, a control circuit connected to the G sensor through a wire harness, and ignition control by the control circuit. An air bag device including an inflator and an air bag that is inflated by gas generated by the inflator, wherein the G sensor has a first resistance connected in series to its contact point, and between the contact point and the first resistance point. A second resistor connected in parallel, wherein the control circuit applies a predetermined voltage to the wire harness, and the voltage of the wire harness determines whether the wire harness is broken or short-circuited and the contact of the G sensor is detected. And a discrimination means for discriminating between ON and OFF.

[Action]

In the above configuration, when the contact of the G sensor is turned on / off, the voltage of the wire harness changes due to the first and second resistors. On the other hand, when the wire harness is broken or short-circuited, the voltage of the wire harness becomes a value different from the voltage corresponding to ON / OFF of the contacts, regardless of the first and second resistances. Therefore, the determination circuit determines the voltage of the wire harness, and the control circuit ignites the inflator only when the G sensor responds to the impact.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals. G
A contact SW ₁ and a resistor R ₁ are connected in series to the sensor 1, and a resistor R ₂ is connected in parallel at both ends thereof. The output from the G sensor 1 is applied to the first input of the comparator CP ₁ via the wire harness W / H. Wire harness W
/ H is connected to the battery power source + B via the resistor R ₃ . The second input of the comparator CP ₁ is connected to the midpoint of the resistors R ₄ and R ₅ connected in series between the battery power source + B and the ground, and the output is input to the CPU 7. CPU7
A lamp L ₂ for warning the abnormality of the wire harness W / H and a transistor Q ₃ for controlling the lamp L ₂ are connected between the IG contact and the IG contact via a fuse of the junction box J / B. Other configurations are the same as in FIG.

When the wire harness W / H is normal, G contacts SW ₁ of the sensor 1 is the shunt resistance R ₁ when it is off, the voltage applied to the first input of the comparator CP ₁ + B × [R
₂ + R ₃ )]. When the contact SW ₁ turns on, R ₁
And R ₂ are connected in parallel, and the voltage applied to the first input of the comparator CP ₁ is + B × {(R ₁ R ₂ ) / [R ₃ +
(R ₁ R)]} (R ₁ R ₂ : parallel resistance value of R ₁ and R ₂ ). On the other hand, the divided voltage + B × {R ₅ / (R ₄ + R ₅ )} of the resistors R ₄ and R ₅ is applied to the second input. Therefore, the comparator CP ₁ outputs V ₁ when the contact SW ₁ is off and V ₂ when the contact SW ₁ is on. Here, V ₁ and V ₂ are V ₁ > V ₂ and 0 <V ₂ <V ₁ <+
Set to B. Also, the wire harness W / H is short-circuited,
When the battery voltage becomes + B or the ground potential, the output of the comparator CP ₁ becomes 0 V or + B, and when the wire is disconnected, the output becomes + B.

In the above, when the wire harness W / H is normal, the contact SW _{1 of the} G sensor ₁ is turned off and on when the vehicle C is normal and at the time of a collision. As a result, the outputs of the comparator CP ₁ become V ₁ and V ₂ , respectively, and at V ₁ (when the contact SW _{1 is} off), the CPU 7 determines the normal state and turns off the transistor Q ₁ . At V ₂ (when contact SW _{1 is} on), the collision state is determined, and the transistor Q
₁ is turned on, the inflator 3 is ignited, and the airbag 4 is turned on.
Inflate. The lamp L ₂ at this time is unlit.

On the other hand, when the wire harness W / H is broken or short-circuited, the output of the comparator CP ₁ becomes 0V or + B, and the CPU 7
Such a voltage is input to determine that there is an abnormality in the wire harness W / H, it is energized lamp L ₂ to turn on transistor Q _3, allowed to light up this. Incidentally, when the battery voltage drops allowed to light the lamp L _1.

〔effect〕

As described above, according to the present invention, since the state of the G sensor and the abnormality of the wire harness can be identified, malfunctions such as non-explosion and erroneous explosion of the inflator can be prevented and reliability is improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a system according to the present invention, FIG. 2 is a circuit diagram showing a conventional configuration, and FIG. 3 is a perspective view showing an outline of an airbag system. 1 ... G sensor, 2 ... control circuit, 3 ... inflator, 4 ...
Airbag, 5 ... Diagnostic unit, 7 ... CPU, 11 ... Warning light, 1 _1L , 1 _1R ... Front sensor, ₁₂₁ , 1
₂₂ ... Cowl sensor, W / H ... Wire harness, CP ₁
…comparator.

Claims (1)

[Scope of utility model registration request] 1. A G sensor having a contact point that responds to a predetermined external force, a control circuit connected to the G sensor via a wire harness, an inflator controlled by the control circuit for ignition, and an inflator generated by the inflator. An air bag device comprising an air bag inflated by gas, wherein the G sensor has a first resistance connected in series to its contact point and a second resistance connected in parallel to the contact point and the first resistance. A control circuit for applying a predetermined voltage to the wire harness, and a determination means for determining a wire harness disconnection or a short circuit based on the voltage of the wire harness and determining whether a contact of the G sensor is on or off. An airbag device comprising: