The Crash Sensors

An airbag is an expandable bolster made to guard the occupiers of the automobile from severe damage in the situation of a crash. The airbag is the part of an inflatable limit structure since the airbag is made to enhance the guard given be the seat belts. The belts too are required to embrace the occupants firmly in place more so side impacts, rollovers and rear impacts. When the collision is detected airbag expand promptly to cushion the unprotected occupier with a big pillow filled with gas. A representative system of the airbag comprises of an airbag module having the gas or inflator generator and an airbag, crash sensors, routing wheel joining the coil, checking unit and the display lamp. The airbag in the car is controlled by the central airbag control unit that observe many devices within the car including the accelerometers, sensors, gyroscopes, brake and side pressure sensors and the sensor for the seat occupancy.

                                                               Figure 1: schematic diagram of the airbag system (Bowers, 2014).

A typical system of the airbag comprises of an airbag module having the gas or inflator producer and an airbag, sensors of the crash, navigating wheel joining the coil, monitoring unit and the display lamp. These constituents are all interrelated by the cabling join and power-driven by the battery of the vehicles. The airbag system holds the charge backup after the eruption has been curved off or after the disconnection of the battery. Dependent on the exemplary the supply of the power backup lasts amid 1 and 10 seconds (Bureau, 2015). Since the mechanisms important to the operation of the system might be inactive for the years the airbag circuits perform an internal self-test during every startup.

Are considered to stop the airbag from the expanding when the car is over the pothole or accident, or in the case of the slight crash. The inflator outbursts into a module having a laced nylon sack and the separate plastic horn pad cover. The module then spasms the steering wheels for the application of the side of the driver and above the glove section for front use of the passengers. In a forward accident similar to the striking a solid block at nine miles per hour the sensor in the front car discover the slowing and sent an electrical signal activating the originator. The initiator has the tinny wire that becomes hot and enters the compartment of propellant. This makes the solid biochemical propellant mostly sodium azide wrapped in the inflator to undertake the chemical reaction (Ching-Yao, 2015).

This reaction gives out inoffensive nitrogen gas that blocks the airbag, through the distribution the increasing nitrogen gas undertakes a procedure that decreases the temperature and eliminates most of the ash and combustion deposit. The accelerometer sensors are used to calculate the speed of the human body and these sensors when installing in the car the forward speed of the passenger can be calculated during the crash. The predetermined motion if the head can be made. If during the crash the momentum of the person’s head is more than the set value then the airbag is deployed (Hickling, 2017).

Airbag Connectors

                                                           Figure 2; parts of airbag (Huang, 2010).

The connectors of the airbag are bright yellow for the easy identification of the cables and the connector. Inside the connectors, there are the jumpers which prevent the airbag from deployment when not intended if the work is being done on the airbag system (Kent, 2016).

Volute spring; this establishes the connection between the column of the ridged steering wheels. It enables the connection between the control unit of the airbag and the gas generator when the wheel rotates (Meyer, 2013).  

Airbag production includes three dissimilar distinct gatherings and stages that associate to form the complete products, the airbag module. The propellant must be made. The inflator parts must be gathered, and the airbag must be stitched after cutting. Some of the manufacturing buy the components that are made already like the initiator and the airbag and then assemble the complete module of an airbag (Meyer, 2013).  

Propellant; it consist of the sodium azide assorted with an oxidizer material that helps the burn the azide of sodium when kindled and received from the vendor and checked to make sure it follows the necessities. After the check, it is put in a good place for storing until required. Also they oxidizer is taken from the vendors outside, inspected and stored. From the storage, the oxidizer and sodium azide is then blended carefully under the sophisticated process control that is computerized. Because of the blasts possibilities, the processing residue takes place in the secluded bunkers. In the event, the safe sensors detect the sparks. Deluge systems of high speed will douse the room with water. After the blending. The mixture of propellant is sent to the storage and presses are used to bandage the propellant combination into the disk form (Ribbens, 2013).

inflator assembly; the components of inflator like the canister, mesh of wire without stains with the ceramic material inside, filter assembly and the originator are taken from vendors and checked. The constituents are collected on the high fabrication line that is automatic. The inflator sub-assembly is added to the propellant and originator to form the assembly of an initiator. Laser welding using the carbon dioxide gas is used to connect stainless steel inflator sub-assemblies. while the friction inertial connecting is used to join inflator of aluminum sub-assembly laser welding uses the beam, to assembles the parts together while inertia friction soldering is just the rubbing the 2 metals until the surfaces are hot to connect together (Sorensen, 2014).

Airbag; the interlaced nylon airbag is taken from dealers and checked for any defect in the material. The airbag textile is die cut to good shapes and stitched, externally and internally to connect the 2 sides properly. After the sewing the airbag, it is inflated and checked for any imperfections seam (Speckert, 2013).

The Manufacturing Process

Finals assembly of airbag module; the assemblage of the airbag is fixed to the inflator assemblage tested. The airbag is crumpled, and the separate horn pad plastic cover is fitted. The completed assembly module is lastly verified after the inspection and also after that, they are packed and shipped to the customers (Bowers, 2014).

other constituents; the residual parts of the airbag system – the sensors, monitoring unit, and the pointer lamp are connected with the module of the airbag throughout the assemblage of the car, all the apparatuses are joined and connect using the wiring harness (Bureau, 2015).

The future airbags look good since there is much different application possible like the helmets and also the future ones will be inexpensive to produce. The design can be improved by using more improved sensors and also more integrated systems. Side-impact airbags are another possibilities that would work alike to passenger and driver airbags. The side impacts air bags are mounted in the door of the panels of the car installed towards the window during the impact to protect the heat. The foam wadding around the entrance assembly would be used to bolster the upper body in a side impact. Head and knee bolster that absorb the energy to complement airbag systems are also being investigated (Hickling, 2017).

Since the effectiveness of the airbag depending on the how the sensors can recognize the crash and how it is simple to activate deployment, the structure should be tuned exactly to the way a detailed car model behave in the crash. Automobiles are discovering the probability of generating future improved airbag system for retrofit. The inflator can also be used, it uses a mixture of the inert gas pressurized which is argon and heat from the propellant to increase the volume if the gas. This system would be cheaper since less propellant would be used. The airbag manufactures should also develop systems that remove the propellant of sodium azide that is toxic in it is not deployed form (Kent, 2016). Also, the coatings should be improved to preserve the airbag and facilitate its opening. The smart sensors should be used to adapt the deployment of the airbag to some condition. These sensors could be used the weight and the size of the occupant and the drivers’ proximity to the steering wheels (Ribbens, 2013).

Conclusion:

The modern car may have many airbag modules include; the drive airbag module side curtain, passenger airbag, knee bolster, inflatable seats and front left and right side airbag sensors. During the crash, the sensor of the car provides the important information to the electronic controller unit of the airbag including the type of collision, severity and angle of impact. Dependent on the results of these calculations the controller unit may use numerous devices like the pre-tensioner of the seat belts, or the airbags. Every device of restraint is normally joined with pyrotechnic devices called electric match or initiator. The electric match has electrical conductors covered in the combustible material that initiates the current pulses between one and three amperes in less than two milliseconds. When the electrode is too hot it kindles the flammable material that in turn initiates the gas generator.

The initiator kindles the solid propellant in the inflator airbag and the propellant that is burning produce the inactive gas that inflates the airbag. the decision whether to deploy the airbag or not is made between 16 to 30 milliseconds after the onset crash and is the airbag deploy very late or gradually, the danger of the damage of the occupant from the contact with airbag may upsurge.  By the use of this data, the airbag’s ECU of the crash logarithm governs if the event crash meet the principles for deployment and trigger many firing circuits to deploy airbag modules inside the car. The airbag deployment of the module is caused by the process of pyrotechnic that is made to be used once.  

Bowers, G., 2014. Understanding Chemistry through Cars. Perth: CRC Press.

Bureau, A. T. S., 2015. Emergency Rescuer’s Guide to Cars Fitted with Airbag. Tasmania: Australian Transport Safety Bureau.

Ching-Yao, 2015. Fundamentals of Crash Sensing in Automotive Air Bag Systems. Perth: SAE International.

Hickling, R., 2017. Sound-Power Flow. Toledo: Morgan & Claypool Publishers.

Huang, M., 2010. Vehicle Crash Mechanics. Perth: CRC Press.

Kent, R., 2016. Air Bag Development and Performance. Colorado: Society of Automotive Engineers.

Meyer, G., 2013. Advanced Microsystems for Automotive Applications. Colorado: Springer Science & Business Media.

Ribbens, W., 2013. Understanding Automotive Electronics. Michigan: Newnes.

Sorensen, P., 2014. Autonomous Vehicle Technology. Melbourne: Rand Corporation.

Speckert, J., 2013. Guide to Load Analysis for Durability in Vehicle Engineering. Toledo: John Wiley & Sons.