Cause analysis of the hottest car fire and Discuss

With the progress of the times, the development of economy and the improvement of people's living standards, the transportation industry is booming, and cars have become an indispensable means of transportation in people's lives. In recent years, the automobile transportation industry has advanced by leaps and bounds. Since 1997, the province has increased more than 400000 motor vehicles. At present, the province has more than 1 million organic motor vehicles. The development of automobile transportation industry brings convenience and rapidity to people's life, but also brings disasters to people. According to incomplete statistics, 440 car fires have occurred in the province since 1997, causing 19 deaths, 50 injuries and direct property losses of more than 12.38 million yuan. Moreover, car fires are increasing year by year, with an average annual growth rate of 30%. Car fires cause great harm and cause serious losses to the lives and property of the country and people. This paper attempts to discuss the technical preventive measures of automobile fire with readers through the analysis of the causes of automobile fire

I Cause analysis of automobile fire

the automobile fire described in this paper is a pure automobile fire accident in addition to the fire caused by traffic accidents, lightning strikes and arson. Automobile fires are mostly caused by vehicle fuel system failure, electrical circuit equipment failure or illegal operation, and only a few are caused by smoking and improper use of open fire

    1. Analysis of fire causes caused by fuel system failure

the function of the fuel system is to mix fuel and air in a certain proportion to supply the engine cylinder to generate power after combustion. There are two main causes of fire caused by vehicle fuel system failure:

(1) fire caused by oil leakage caused by rupture or looseness of oil supply system container and pipeline. The oil supply system is mainly composed of oil pump and carburetor (both of which are improved into electronic injectors for new vehicles), fuel tank and oil pipe. In the process of use, due to corrosion, collision, vibration, aging and other reasons, containers and pipelines will be broken, pipeline joints will be loose, oil switches will not be closed tightly, and fuel will leak out. Fuel (especially gasoline) volatilizes and accumulates to form a mixed flammable and explosive gas with air, which will cause combustion or explosion in case of open fire. As long as one part of the fuel system breaks down and leaks oil more than once, it will inevitably cause a fire accident

(2) the mixed gas delivered to the engine cylinder is out of proportion, causing the carburetor to backfire and cause a fire. The failure of a link (component) in the oil supply system reduces the supply of gasoline, and the amount of oil entering the carburetor is insufficient. When the carburetor works, the mixture supplied to the engine cylinder is too thin, and its combustion speed is very slow, which can continue until the inlet valve is opened, so that the experimental data cannot be kept and printed.) the flame may flee into the intake pipe and ignite the mixture in the intake pipe and the carburetor throat, And cause carburetor backfire. The backfire of carburetor may burn the carburetor and air filter, and will cause the symptoms of power reduction and difficult acceleration. It is extremely dangerous for individual drivers to use the direct fuel supply method to supply oil to the engine when the vehicle fuel system fails. Once the carburetor backfires, a fire will occur. In addition, when the carburetor breaks down and the mixed gas supplied to the engine cylinder is too thick or the cylinder has oil channeling, the gasoline cannot be fully burned in the engine cylinder, and the exhaust pipe emits thick smoke and sparks, accompanied by sound, that is, the phenomenon of "shooting". If there are oil stains or other flammable and combustible objects on the road under the vehicle at this time, it may cause a fire. For example, in the summer harvest, when the car passes the road with straw, the sparks from the car exhaust pipe will ignite the straw and cause a fire

a year-on-year increase of 45.60%

2 Cause analysis of fire caused by circuit system failure

the circuit system of the automobile is relatively complex, with dense electrical lines. Its electrical equipment includes battery, generator, ignition line, air conditioning, lighting, etc., which are mainly responsible for power generation, charging, starting the engine, ignition, lighting, air conditioning, acousto-optic signals, etc. according to the functions of each part of the circuit, the automobile circuit system can be divided into the following subsystems: power supply system Starting system, ignition system, instrument system, lighting system, sound system and signal system. Under normal circumstances, the fire risk of the automobile circuit system is small, but it will cause a fire due to the driver's illegal operation or a fault somewhere in the circuit. The main reasons are:

(1) illegal operation causes the battery to produce an arc and cause a fire. The current capacity of automobile battery is very large, generally 180 amperes/hour. Usually, when the driver carries out maintenance work on the vehicle, he is greedy for convenience, only washing the appearance or checking the tires, water tanks and so on, rarely maintaining and protecting the battery wiring and contacts, and rarely checking whether the contacts are loose and whether the wiring insulation is damaged and aging. Once the contact is loose or the wiring insulation is damaged and aged, it is easy to cause short-circuit ignition between the wiring and the wiring, between the wiring and the vehicle body due to the bumpiness of the car during driving, or short-circuit ignition due to the jumping of the contact, which may also cause fire

(2) the fault of the reverse flow cut-off in the vehicle regulator causes a fire. The working principle of the countercurrent breaker is: when the generator runs at low speed and the voltage does not reach the rated value, the contact of the countercurrent breaker is disconnected and the engine does not supply power to the outside; When the speed of the generator increases and the voltage rises to the closing voltage of the countercurrent breaker contact, the countercurrent breaker contact closes, and the generator supplies power to the electrical equipment and storage battery; When the generator speed decreases and the voltage is lower than the battery voltage, the battery discharges in the opposite direction to the generator, and the electromagnetic switch contact of the countercurrent breaker is disconnected, which automatically cuts off the circuit between the generator and the battery. Its function is to prevent the battery from discharging in reverse to the generator. The contact spring of the countercurrent cutter breaks or falls off, or poor contact will make the contact (white actually does not make the declaration of conformity gold contact) close for a long time, burn and bond, and lose the function of cutting off the reverse current, so that the current in the battery returns to the generator, which will cause the generator coil to change. 1. The extensive plastic granulator is a combined and intelligent plastic granulator, and the heat will produce a high-temperature fire. Many cars parked in the warehouse after driving have electrical circuit burns and car fires, which are caused by the failure of the countercurrent breaker. During fire regulation, the regulator can be sent to the relevant inspection department to check whether the various parameters in the regulator meet the technical requirements

(3) fire caused by electrical circuit system. With long-term operation of the vehicle, the insulation of electrical lines (especially high-voltage electrical lines) and electrical equipment on the vehicle ages quickly, which is very easy to cause leakage, short circuit, and even fire; The vehicle vibrates greatly when driving, and the joint between the electrical circuit and the electrical equipment is easy to loosen, resulting in poor contact and electric sparks, and fire will happen if the contact is poor for a long time; When the vehicle is being repaired, the maintenance personnel are careless and operate improperly, which artificially causes the exposure of electrical lines and the failure of electrical equipment, resulting in phase line short circuit, overload, high temperature and high heat, causing the ignition of electrical lines or electrical equipment

(4) the air conditioning system in the car causes a fire. Due to improper installation of the cooling pipe of the air conditioning system, the cooling pipe is close to the combustible and the heat dissipation is not smooth, which is also very easy to cause a fire

    3. Cause analysis of fire caused by smoking

smokers often throw cigarette butts or matches around when they are not extinguished. If the cigarette butts contact the combustible seat cushion, or the cigarette butts fall directly on combustible materials or combustible decorative materials, fire accidents often occur. Especially when the driver and passengers throw cigarette butts out of the window when the car is driving, the cigarette butts will be blown back to the back of the car or the rear cargo warehouse due to the effect of the wind. After the car is parked, the fire happens suddenly

    4. Cause analysis of fire caused by man-made arson

the perpetrator retaliated by arson in order to vent his private anger, or the owner ordered others or burned the vehicle himself in order to defraud insurance money