Pic. 1.57. Megane car security system: 1 - seat belt pretensioners (driver and front passenger); 2 - pyrotechnic reels of seat belts on the rear side seats; 3 - pretensioners of the lap branch of the driver's and front passenger's seat belts on the 5-door «hatchback»; 4 - anti-slip airbags for the driver and front passenger on the 3-door «hatchback»; 5 - front airbags with two gas generators (two-volume); 6 - side chest airbags in the backs of the front seats; 7 - side curtain airbags; 8 - side chest airbags for the rear seats (if the car is equipped with them)
The security system of the Megane car is shown in fig. 1.57.
General information
In a severe enough frontal impact, seat belts hold the driver and passengers in place.
The front shoulder belt pretensioners and the rear pyrotechnic reel retractors tighten the seat belts so that they fit snugly against the body.
The programmable restraint system limits the force with which the belt is pressed against the body.
Front airbags deploy:
- from the center of the steering wheel to protect the driver's head;
- from the dashboard for the front passenger.
Lumbar pretensioners for front seat belts (5-door modification) or anti-skid airbags (3-door modification) tighten the seat belts to protect the lower body.
Note. The degree of inflation of the driver's airbag can be adjusted by the ECU depending on:
- - seat position;
- - impact force.
In the event of a sufficiently severe side impact, the front side chest airbag located in the front seat (from the side of impact), when activated, protects the chest of the front seat occupant on the door side. Rear side airbag, if the vehicle is equipped with it, located in the sidewall of the body on the corresponding side (from the side of impact), protects the chest of the person sitting in the back seat from the side of the door. air curtain (from the side of impact) protects the head of a person sitting in the front or back seat from the side of the door.
Pretensioners, seat belt reels, anti-skid airbags, front and side airbags may deploy in various combinations depending on the severity and location of the impact.
When the pyrotechnic gas generator is activated, there is a popping sound and light smoke is emitted.
Note. Power to the ECU and igniters under normal operating conditions is supplied from the vehicle battery. However, the airbag ECU has a built-in backup power supply in case of battery failure during the initial phase of an impact.
Note. When the seat belt pretensioners or airbags are deployed, the computer is completely blocked and a warning light on the instrument panel lights up. In this case, the ECU must be replaced (under the influence of ignition energy, some elements lose their nominal characteristics).
Note. After installing all the elements, perform a system check using a diagnostic tool.
After hitting:
- when the pretensioners are activated, replace the seat belts, if they were fastened, as well as the seat frame (power to the pretensioners of the shoulder branches of the belts is supplied sequentially);
- if the rear pyrotechnic coils are triggered, replace the seat belt together with the pyrotechnic coil (pyrotechnic coils are powered in series);
- when the driver's front airbag deploys, the steering wheel and its fastening bolt must be replaced;
- after deployment of the front passenger airbag, replace the instrument panel;
- when the seat side airbag deploys, replace the seat frame;
- when the anti-slip airbag deploys, also replace the seat frame;
- when the curtain airbag deploys, install the plate and replace the deflector.