JPH10147208A - Power source cutoff device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a power cutoff device as cuts off the electric power source after an airbag of a vehicle is expanded. SOLUTION: An ignition device of an airbag inflator 12 is electrified, according to a control signal to a driving circuit 17. Then, a great deal of nitrogen gas is generated from a gas generating agent, in which an igniting agent is ignited through electrifying so as to make a flame propagate, in order to expand the airbag instantaneously. On the other hand, an electrifying controlling transistor 19 is activated according to a control signal impressed to its base, so that an actuating circuit 9 is electrified so as to operate a relay 8. When the relay 8 operates, a short-circuit 7 is turned on so that a short-circuit current flows. Owing to this short-circuit current, a fusible link 3 is fused so as to cut off a battery power circuit 4. Since the time required for fusing the fusible link 3 is longer, compared with the case in an ordinary fuse, the battery power circuit 4 is cut off after the airbag of a vehicle has completely been expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power shutoff device for shutting off power after an airbag of a vehicle is deployed.

[0002]

2. Description of the Related Art In order to ensure the safety of vehicles, Japanese Patent Application Laid-Open Nos. Hei 6-227335 and Hei 6-321027 disclose a power shut-off device which shuts off a power supply in a collision or the like to prevent a fire due to a short circuit. It is disclosed in the gazette.

[0003]

Problems to be Solved by the Invention
The power cutoff device disclosed in No. 5 has a mechanical acceleration sensor, an on / off switch, or the like added to or incorporated in a battery. Therefore, it is necessary to ensure the sealing of the power supply cut-off device to prevent infiltration of rainwater and the like, and to prevent the initial function and performance of each mechanical component from being impaired with the passage of time. Also, Japanese Unexamined Patent Publication No.
The power supply shut-off device disclosed in Japanese Patent No. 1027 calculates the total value of the current value flowing from the battery and the current value that is actually used and used in the device, and compares the current values to determine whether a fault has occurred. When it is determined that the current is generated, the current flowing from the battery is cut off. However, in an emergency such as when an airbag mounted on a vehicle is deployed due to a collision, it is desirable to shut off the power supply after the airbag is securely deployed for ensuring the safety of the occupant and the vehicle. The present invention has been made in view of the above, and an object of the present invention is to provide a power shutoff device that shuts off power after an airbag of a vehicle is deployed.

[0004]

According to the present invention, there is provided a power cutoff apparatus comprising: a power supply, an airbag inflator, a power supply circuit to the airbag inflator connected to the power supply, and a shock-absorbing device. A safing sensor that detects a predetermined deceleration and turns on the power supply circuit, an airbag sensor that generates an electric signal corresponding to the magnitude of the acceleration, and a predetermined sensor based on the electric signal of the airbag sensor. A control circuit for performing the calculation of the above, a drive circuit for energizing the ignition device of the airbag inflator, a short circuit connected to the power supply in parallel with the power supply circuit, And a fusible link for shutting off the power supply. The control signal is output when the operation value of the control circuit exceeds a preset value. Drives the circuit and short circuit, characterized in that so as to cut off the power supply after air bag deployment.

[0005]

According to the power supply shut-off device having the above-described structure, when the vehicle decelerates due to a collision or an impact, and when the calculated value of the control circuit exceeds a set value due to a sudden change in acceleration, the power supply cut-off device is operated. By the control signal output from the control circuit,
When the drive circuit and the short circuit are driven, the ignition device of the airbag inflator is energized to deploy the airbag, and the short circuit current flowing through the short circuit causes the fusible link to melt and cut off the power. Since the time required for the fusible link to be blown is longer than that of a normal fuse, the power supply can be cut off after the airbag of the vehicle is securely deployed, and the safety of the occupant and the vehicle in the event of a collision is further enhanced.

[0006]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram of the power supply cutoff device 1. The power cutoff device 1 of the present embodiment is configured in combination with an airbag system. In the airbag system, an airbag inflator 12 is controlled by an airbag computer 11 to deploy the airbag at the time of a collision. A power supply circuit 4 for various electrical components, an ignition circuit 6 and a short circuit 7 of the battery power supply circuit 4 are connected in parallel to a battery power supply circuit 4 having a battery 2 and a fusible link 3 interposed in series. A relay 8 is interposed in the short circuit 7. The operation circuit 9 of the relay 8 is connected to the airbag computer 11.

The airbag inflator 12 instantaneously generates gas for deploying the airbag.
It is composed of an ignition device, a transfer agent, a gas generating agent and the like (all not shown). Airbag computer 11
Are a backup power supply 13, a control circuit 14, a safing sensor 15, an airbag sensor 16, a drive circuit 17,
A power supply circuit 18 for the airbag inflator 12 and an energization control transistor 19 are provided. The backup power supply 13 is connected to the power supply circuit 5 for various electrical components and the ignition circuit 6 and discharges when the power supply system fails in the event of a collision to supply power to the airbag system or to reduce the power supply voltage. Or to boost pressure. The control circuit 14 includes a CPU, a storage element, an interface, and the like, and performs a predetermined calculation based on an electric signal from the airbag sensor 16 to output a control signal.

The safing sensor 15 turns on the power supply circuit 18 to the airbag inflator 12 when the deceleration exceeds the set value due to the impact. The airbag sensor 16 uses a piezo element to input an electric signal corresponding to the magnitude of the acceleration to the control circuit 14. The drive circuit 17 is driven by a control signal from the control circuit 14 and energizes the ignition device of the airbag inflator 12. The activation circuit 9 of the relay 8 is connected to the collector of the conduction control transistor 19. And
When the control circuit 14 conducts according to the control signal, the operation circuit 9
Is energized, and the relay 8 operates.

The operation of the power cutoff device 1 having the above configuration will be described. When a deceleration exceeding the set value is applied due to the impact at the time of the collision, the safing sensor 15 turns on the power supply circuit 18 to the airbag inflator 12. Then, an electric signal corresponding to the magnitude of the acceleration is input from the airbag sensor 16 to the control circuit 14. The control circuit 14 performs a predetermined operation based on the electric signal. When the calculated value exceeds a preset value, the control circuit 14
Control signals are output to the control signal 7 and the conduction control transistor 19, respectively.

The ignition device of the airbag inflator 12 is energized by a control signal to the drive circuit 17. The energization heats the filament in the igniter and ignites the igniting agent. At the same time, a large amount of nitrogen gas is generated from the gas generating agent through which the fire propagates, and the airbag is instantaneously deployed. The conduction control transistor 19 is turned on by the control signal applied to the base, and the operation circuit 9 is energized and the relay 8 is turned on.
Operates. When the relay 8 operates, the short circuit 7 is turned on and a short circuit current flows. The short-circuit current blows the fusible link 3 and shuts off the battery power supply circuit 4.

Since the fusing link 3 requires a longer time to blow than a normal fuse, the battery power supply circuit 4 is cut off after the airbag of the vehicle is securely deployed. Accordingly, there are advantages that the operation of the airbag system for ensuring the safety of the occupant at the time of the collision can be ensured, and that the trouble of the vehicle caused by the continuation of the power supply after the collision can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a power cutoff device 1. FIG.

[Explanation of symbols]

 1. Power cutoff circuit 2. Battery 3. Fusible link 4. Battery power circuit 7. Short circuit 8. Relay 11. Airbag computer 12. Airbag Inflator 14 ... Control circuit 15 ... Safing sensor 16 ... Airbag sensor 17 ... Drive circuit 18 ... Power supply circuit 19 ... Transistor for energization control

Claims (1)

[Claims] 1. A power supply, an airbag inflator, a power supply circuit to the airbag inflator connected to the power supply, and a safing sensor for detecting a predetermined deceleration based on impact and turning on the power supply circuit. An airbag sensor that generates an electric signal corresponding to the magnitude of the acceleration, a control circuit that performs a predetermined operation based on the electric signal of the airbag sensor, and a drive that energizes the ignition device of the airbag inflator. A short circuit that is connected to the power supply in parallel with the power supply circuit, and a fusible link that cuts off the power supply by fusing due to a short-circuit current flowing through the short circuit. The drive circuit and the short circuit are driven by the control signal output when the value exceeds the set value, and the power supply is shut off after the airbag is deployed. Power cutoff device, characterized in that the the like.