Fig. 19. Main elements of the airbag system: 1 — cover; 2 - airbag; 3 - actuator; 4 - metal container; 5 - "clock" spring; 6 — electronic control unit; 7 - signal lamp
The entire system, including diagnostic elements, is controlled by an electronic control module using signals from sensors. One of them generates a signal during acceleration and deceleration, while the other only detects deceleration. Both sensors are connected in series, so if they both detect a sudden deceleration greater than the set value, the airbag system is triggered. Electronic control module 6 (Fig. 19) serves to monitor the operation of the system. If damage is detected, signal lamp 7 flashes or lights up continuously, warning the driver of a system malfunction. If the system is in good working order, the lamp lights up for 4 seconds after the ignition is turned on, and then goes out.
The so-called "clock" spring 5 transmits the necessary signals between the electronic module and the airbag module on the driver's side. The spring is fixed to the steering column switch holder and consists of fixed and movable parts that are connected to each other by a twisted Mylar tape with conductive tracks. The Mylar tape can be wound and unwound during the rotation of the steering wheel, on which the movable part is fixed, so that electrical contact between the electronic control unit and the airbag module is maintained at all times. The "clock" spring simultaneously transmits electrical current for the horn and the speed controller switches, if installed.
The airbag actuator is located in a metal container on which the folded airbag is located. The unit is covered with a lid. The module is installed on the steering wheel.
The actuator produces the required amount of non-toxic gas to fill the airbag. One actuator 3 is used on the driver's side, two on the passenger side next to the driver. The airbag 2 on the driver's side is almost round, on the passenger side next to the driver it corresponds to the shape of the instrument panel. The cover 1 on the driver's side is firmly connected to the metal container 4 and cannot be separated from it. It is equipped with a certain number of invisible rupture points, due to which the airbag quickly deploys if the system is triggered.
In a frontal collision, the following occurs in the airbag system:
- both sensors detect sudden
If both sensors close simultaneously, electrical current flows to the actuator, which activates the gas ignition;
- When the gas burns in a metal container, nitrogen dioxide is formed. The gas is filtered and cooled during the inflation of the airbag;
- the airbag, which is filled with gas, breaks the cover and quickly deploys in front of the passenger. The entire process takes place in a matter of seconds;
Fig. 20. Airbag after gas release
- after filling, the gas is pushed out through the holes in the material. The airbags immediately deflate and look like the one shown in Fig. 20. They can be easily moved aside to clear the passage.
Warnings
1. Airbags contain a flammable but non-explosive solid substance, so they will not explode in an accident or fire.
2. The steering wheel, steering column and airbag material do not heat up after an accident. The "smoke" that disperses into the air when the airbags deploy is non-toxic, as it is talc or starch that the airbag is treated with.
3. When the battery is disconnected, the airbag system is disabled.