Car driving must be uninterrupted oil supply to the engine, aspirated, not only supply, but also enable them to properly mix, burn gone smoothly but also to exhaust emissions.
End, stored in a tank of fuel needs within the fuel tank into the engine, must have pump and piping. In order to prevent contaminated fuel needs to filter to filter. Outside air containing dust, the air into the engine air filter needs to be filtered.
Clean air and fuel necessary to prepare, you need a ministry is not the default one, that is the carburetor. Carburetor must be dry two things: First, it must be allowed to fuel vaporization; second, to a certain percentage of vaporized fuel and air mixture mixed form.
From outside air into the carburetor after filtration through the air into the volume of the number of position changes by the choke control. Crossed the carburetor air inside the suction pipes produce the fuel from the float chamber through the suction nozzle, and its atomization. Atomization of the fuel and air mixture through the intake manifold is no cylinder inhalation. Mixture into the volume by a
Accelerator Pedal control, which is located inside the carburetor throttle (
Throttle ) Controlled. From the fuel pump pumping fuel from the float chamber float chamber float control. Float in the float room with how much oil lifting, when the float room full of gasoline, the float float, with its needle to block the inlet. Driver size by controlling the throttle to change the engine speed, which is a simple carburetor works. The concentration of the mixture as the throttle gradually thicken the Great.
Car engine working conditions to change frequently in a wide range, such as cars started in the intersection waiting for the green light before and prior to release, the engine as
Idle Operation, this time the load is zero, the minimum throttle opening, the lowest speed; car full of climbing, the throttle fully open, but the speed is not high; in the flat roads, not full-throttle, engine is moderate load, speed and medium speed; in highway driving, the engine may be at full capacity, maximum speed.
Work in so many complicated situations, requirements for the mixture can not be stereotyped. For example, in idling and low load, the former requires the mixture to be very strong, which requires concentration gradually thinning; in the middle load, in order to
Saving , Also requested the supply of fuel consumption the smallest carburetor mixture; at full load, in order to allow the engine to issue the maximum power required to provide rich mixture carburetor. In addition, vehicle cold-start, require stronger sense of mixture; acceleration required to open the carburetor when the throttle suddenly, the additional supply of oil and so on.
In summary, the gasoline engine in the normal state, in small, medium load requirements can increase the supply of carburetors as the load gradually thinning by the darker mixture, at full load, also requested by the mixture thin thicken, according to the above requirements, relying on the previously described simple carburetor can not be met.
To meet these requirements, in Modern Carburetor is equipped with a series of mixed gas concentration compensation device. Such as the main supply pump, idle system, fuel-efficient devices to speed up the system and starting system, to ensure that the gasoline engine under different working conditions, the carburetor can supply the appropriate concentration of the mixture.
Even though the carburetor a small man, but so much within the integrated system, the structure becomes more complex. Seeds to ensure the carburetor can often work, so its periodic maintenance is very important. The main disadvantage of using the carburetor to the cylinder inflation and the distribution of the mixture is not ideal, affecting engine
Power And economy, rising to meet the discharge requirements are very unfavorable. In recent years, countries in order to meet environmental requirements, direct fuel injection method used to replace the carburetor. The advantage of direct injection pneumatic high efficiency output power, mixed-gas distribution uniformity, changes in working conditions under the best ingredients of the mixed gas supply, low fuel consumption. Disadvantage is difficult to the cylinder head layout, manufacturing costs are high. Can be divided according to the location of injection cylinder injection and intake manifold injection are two kinds of control systems by points, with mechanical and electronic injection type (EFI) two.
From the 60's, the electronically controlled fuel injection system that is manufactured in Europe and the United States and other countries gradually adopted car engine. In the EFI system, there can be precisely controlled mixture of conditioning ingredients, plus three-way catalytic converters fitted to exhaust a large reduction of harmful ingredients.
The basic principle EFI system through various parts in
Sensor , The feedback collected to enter into a microcomputer for processing, which would issue instructions to control the mixture ratio of air and fuel, so that the mixture of gas supply to meet the engine needs in a variety of conditions. Such as computers and the air flow sensor engine speed, throttle position and even the cooling water temperature and air temperature sensors collect information and calculate the fuel injection through the judge's basis for determining the fuel injector opening time, to issue directives to spray oil cooler, so that it injection.
In different parts of the sensor receiving different information: such as distributor ignition coil engine rpm to accept the information; air flow sensor air flow of information received inhaled; starter switch starting to accept the information; throttle throttle position switch information; cooling water temperature, water temperature sensor information received, air temperature, air temperature sensor to accept the information. This information is fed back to the computer through the circuit.
In the EFI system, the most important computer components except the number of injectors on the outside. Generally only one engine each cylinder injector, intake valve at the top. Fuel through the injector and then into the trachea and from the air mixed into the cylinder.
Emission regulations in order to meet the requirements of some of the cars in the EFI system has a hybrid gas-conditioning systems. It is mainly used in the airway of an oxygen sensor, it can feedback to the computer dilute or concentrated mixture of information. Computer instruction based on information re-Injector, get the correct amount of fuel injection.
The new generation of engine fuel injection systems and ignition systems have been combined into one, reflects the mixture composition and ignition time, optimal control, greatly improved the performance of the engine.
Described above is a multi-point injection. As the jet spray is used each way, 4-cylinder machine 4 jet injector, respectively, each turn the crankshaft, each cylinder injection time.
In addition, the current there is a single point injection system, also known as throttle body injection system. In the multi-cylinder engine is only one fuel injector, throttle body mounted on top of