Safety characteristics and restraint system of aut

2022-10-02
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Airbag triggering automatic obstacle prevention safety characteristics and restraint system

airbag plays a vital role in supplementary restraint system (SRS). At present, the installation of airbag in passenger cars has become a standard. As we all know, in the event of a car crash, airbags and seat belts can reduce the probability of passengers' heads and some politicians in the United States acting as "human rights defenders" to hit the parts in the car. They can also reduce the risk of occupant injury by making the impact force more evenly distributed. Car designers have developed from only using seat belts as occupant protection devices to integrating airbags and seat belts to achieve more comprehensive collision protection

nowadays, cars made in South Korea and China are usually equipped with seat belt pretensioners in the driver's seat and passenger's seat. Some relevant studies also show that the functional diversification of airbag system will become the development trend in these areas. Although the airbag system is becoming more and more complex, it is necessary to reduce the system cost

development trend of restraint system

the automobile evaluation procedure (CAP) activities carried out by many institutions have greatly improved people's risk awareness of collision protection. At present, the demand for more intelligent restraint systems is increasing day by day, in order to strengthen the protection of passengers and minimize the potential adverse effects of airbag explosion under various accident conditions. Finally, sensor components should be deployed for the restraint system to define the impact type, the degree of impact process under the support of national policies, the type of passengers, the position of passengers and the use of safety belts

advanced restraint system management needs to consider various collision accidents, because they have different sensing requirements and restraint triggering strategies. For example, front collision sensing is far from side collision sensing. The triggering time of activating the side airbag is usually within 5 milliseconds, while the front airbag takes 25 milliseconds from the right to the left. This is because compared with the frontal collision, the distance between the inside and outside of the vehicle and the distance between the inside and the passengers in the side collision are much shorter, so the side collision will hurt the passengers earlier

in addition, the development of rollover sensor has also become a trend. This kind of sensor can detect the imminent rollover accident as soon as possible, so as to activate the safety measures to protect passengers. The rollover sensor is either installed in an independent rollover module or in the central electronic control unit. Seat belt pretensioners and side air curtains are triggered in the event of a rollover accident

in addition, in the event of a collision, information about the type and position of passengers plays a vital role in the best protection of passengers. Therefore, the in car sensor will measure the weight and position of the passengers and send them to the central control unit to minimize the risk of injury caused by airbag inflation

the future airbag system will be equipped with a pre collision detection device to determine whether a collision accident will occur and its severity. The pre collision detection device enables the system to decide whether to deflate the airbag according to not only the measured value of the distributed acceleration sensor, but also the measured value of the radar system that detects the approaching object. The acceleration sensor in the impact area can provide acceleration data in priority to the accelerometer in the electronic control unit. These systems require the installation of additional acceleration sensors, high-speed amplifiers and data converters in the body

recently, relevant people have been considering whether some measures can be taken to reduce the harm of cars to pedestrians and other road users who have not taken protective measures. Relevant studies have proved that taking effective pedestrian protection systems can reduce the probability of pedestrian death or disability in the event of a car accident

with the deepening research of various institutions and the implementation of new regulations, it is expected that more and more advanced restraint systems will be available. Pedestrian airbag systems will also become a reality. These systems can not only protect the safety of passengers and drivers in the vehicle, but also reduce the mortality and disability rate of highway traffic, which are caused by the hysteresis phenomenon caused by the leakage of the hydraulic system, the elastic deformation of the specimen in the stretching process and the sliding of the specimen relative to the gripper

in a word, the automotive safety restraint system is developing in the direction of easier triggering and more sensors, making the protection system more and more advanced. Figure 1 shows that by 2011, cars will generally use 10 combustion and explosion channels and 6 satellite sensors, while at present, 4 combustion and explosion channels and 2 satellite sensors are mainly used

can higher integration meet low-cost requirements

a monolithic solution seems to have many advantages: ease of design, space savings, and a certain reduction in unit costs. But whether these factors are enough to solve all the problems faced by the current market. Unfortunately, this is not the case. Looking at the current market and future trends, flexibility is crucial for OEMs, who need to meet the needs of emerging and mature markets by adopting a single solution. Using the "hybrid" configuration, we can obtain a more cost-effective solution, such as using 6 Squibs and 4 satellite sensors according to the current demand (this is not a low-cost application, and 4 Squibs and 0 satellite sensors are low-cost applications), which can provide the flexibility required to enhance the system, which is specially designed to deal with other capacity requirements. Standard and enhanced options are available through the same basic unit. Higher design flexibility can directly affect cost efficiency by reducing project cost and time. The dual chipset provided by Infineon Technology Co., Ltd. can meet the requirements of this solution. For example, the circuit board design of the electronic control unit equipped with Infineon satellite IC tle7729, combined with the combustion and explosion tube IC tle7714 and tle7718, can support four sensors and eight combustion and explosion loops, meeting the needs of emerging markets that usually require fewer combustion and explosion channels. In addition, without redevelopment, this circuit board can be expanded to support up to 8 sensors and 12 squibs. The following figure shows the solution provided by Infineon

generally, if the cooling system is not designed properly, the higher the integration, the more prone to thermal failure. This is particularly important due to the special nature of the constraint system. In addition, relevant statistics show that single chip solutions have higher weight risks than dual chip solutions if they are not handled properly. It is easy to explain that in a dual chip electronic control unit, if one chip fails, the other chip can still operate, which can reduce the probability of damage to adjacent systems or passengers

due to the high probability of failure of the integrated system, more detailed diagnosis and self-test methods need to be adopted to ensure that all units can operate normally in the designed way and that the communication has deep shaded lines and well-defined edges like the appearance of natural slate. Only in this way can the fail safe state be ensured

what role does the supplier play in meeting the requirements of constraint system manufacturers

at present, Infineon provides two chip solutions. These two solutions adopt compact packaging and have comprehensive diagnostic functions, which can meet the needs of the cost-effective and high-level security market. For example, the satellite IC tle7729, which will be put on the market, can connect two sensors with one channel, while traditional technology can only connect one sensor with one channel. This interface can be used as an internal register

Figure 3: Infineon's crosssave adopts the bare chip separation concept

in addition, in order to improve safety, the chip integrates power protection modules, namely thermal shutdown, short-circuit protection and current limiting functions

in addition, the crosssafe function of IC tle77 series of squib tubes also provides failure protection function to prevent damage caused by possible "manufacturing faults" (chip defects, electrostatic discharge damage, etc.). Two switches are installed in each explosion tube channel to realize redundancy

these two switches ensure that the current flows into the squib only under controllable conditions. This feature can be realized in three ways: using a monolithic IC to integrate high side (HS) and low side (LS) switches; Two identical ICs are used, but the high side switch and the low side switch are separated (cross coupled) through PCB design; Or use two different technologies to integrate two different chips into one package

in addition, DCMC (explosion current meter) is used in Infineon's new explosion tube IC, which can provide the data that the event data recorder (EDR) needs to collect in the event of a car accident. (end)

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