1、 附录 SRS Airbag Airbag are known as Supplemental Restraint System（ SRS） and has become more common in modern cars. The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door. If airbags are fitted, the steering wheel cover
2、and dashboard cover will usually have the words airbag or SRS airbag stamped into them. The sensors detect impact and signal the airbag to inflate. At least two sensors must be activated for the airbag to inflate. There are usually five sensors: two at the radiator support, one at the right-hand fen
3、der apron, one at the left-hand fender apron, and one at the cowl in the passage compartment (A few system use only sensors one in front of the radiator and anther in the passenger compartment). There is an interlock between the sensors, so that two or more must work together to trigger the system.
4、The airbag systems are designed to deploy in case of frontal collisions only. The SRS airbag inflator contains a solid chemical gas generator. The solid chemicals are safely stored in a metal chamber inside the SRS airbag module. Each inflator is sealed to keep out moisture. SRS airbag are designed
5、to deploy in moderate to major crashes only and should not deploy in minor crashes. The following four steps show how the SRS airbag works: 1. In an impact, sensors in the car detect the sudden deceleration. If the crash id severe enough, electricity flows to the inflator and causes ignition of the
6、gas generator. 2. The gas generator then rapidly burns in the metal chamber. The rapid burning produces inert gases and amounts of dust. The insert gases and dust are cooled and filtered during inflation of the airbag. 3. The inflating airbag splits open the trim cover. The airbag then rapidly unfol
7、ds and inflates in front of the occupant. 4. After inflation, the gas is vented through openings or open weave areas in the airbag. These steps take place in a fraction of a second. Airbags deflate in under a second and may be pushed aside for occupants to exit. See Fig.10-1 There is a general misco
8、nception that airbags provide a soft cushion and will prevent bruising or other minor injuries in low severity crashes this is incorrect. SRS airbags are designed to reduce peak loads on the head chest in severe crashes (those where death or long term brain injury are possible). When deploying, the
9、airbag is firm, but it absorbs energy as the gases are released through the vents. While airbags significantly reduce the risk of serious or fatal injury in crashes, there are some risks from the development of airbags in low speed crashes. For this reason modern cars use a range of intelligent sens
10、ing functions to ensure that a crash is really happening (not just a bump in the road or a minor knock in the car park) and to fire airbags at the best time. This reduces the likelihood of airbags deploying in minor crashes. The new SRS airbag system uses a word-first dual inflator, two-stage deploy
11、ment system for front passengers. The system has two separate inflators that can be activated separately or together, depending on the vehicle speed and other factors, such as whether the passenger is wearing a seatbelt. In relatively low-speed impacts, the inflators are activated one after the othe
12、r for slower inflation. At higher speeds, both inflators are activated simultaneously for quick, effective protection. The system detects if seatbelts are being worn, adjusting the airbag inflation threshold speed for maximum effects and minimum risk. This SRS airbag also controls the seatbelt prete
13、nsioners, switching them off in low-speed accidents to prevent unnecessary risk to vulnerable passengers, such as the elderly. A passenger-sensing device control side airbag development to prevent potential injuries from these fast-activating systems. Six sensors are built into the front passenger s
14、eat. One detects the size of the passenger, and another determines whether the passengers head is in the development path of the airbag. If the sensors detect a child asleep with his/her head learning to one side, the side airbag is deactivated to prevent head or neck injuries from airbag deployment
15、. For even safer SRS airbag control, a sophisticated three-point sensing device has been developed to determine the strength, direction and type of impact. The system has a central sensor and two satellite sensors on each side of the vehicle. This system is particularly suited to distinguishing betw
16、een the impact of a tire hitting a kerb and a strong impact. It triggers only the appropriate airbag or airbags. In the future, we will further expand the number of vehicles equipped with 6 air bags by adding side airbags that protect the arm and chest areas and curtain airbags that protect the head area in side impacts. See Fig.10-2 Fig.10-2 Six-airbag position 1/4 Curtain airbag system 2/5Side airbag system 3Passenger airbag system 6Driver airbag system
