When the car is running, it is necessary to supply oil to the engine without interruption, not only for the supply, but also to mix them properly and to burn the exhaust gas. Fuel needs to be stored in a tank, the fuel tank into the engine, there must be oil and pipes. In order to prevent contamination of the fuel, the filter is required to be filtered. The outside air contains dust, air into the engine needs air filter Sensor to be filtered. How clean air and fuel as needed to prepare, you need an indispensable part, that is, carburetor. Carburetor must do two things: First, it must make fuel vaporization; Second, the vaporization of fuel and a certain proportion of air mixed to form a mixture.
The air from the outside is filtered into the carburetor, and the amount of air is controlled by the change in the position of the choke. The air runs through the throat in the carburetor to draw the fuel from the float chamber through the nozzle and atomize it. The atomized fuel and air are mixed and the intake manifold is inhaled by the cylinder. The intake of the mixture is controlled by an accelerator pedal, which is controlled by the throttle (throttle) in the carburetor. The amount of oil pumped into the float chamber by the petrol pump is controlled by the float in the float chamber. Float in the float room with the amount of oil and lift up and down, when the float is full Suction Control Valve of gasoline, the float, with its needle valve will be blocked into the port. The driver changes the speed of the engine by controlling the size of the throttle opening, which is the principle of the simple carburetor. The concentration of the mixture is as the throttle is large and gradually become thicker.
The working condition of the automobile engine should always change in a wide range, such as before the start of the car and at the intersection waiting for the green light to release, the engine for idling operation, this time the load is zero, the throttle opening minimum, the lowest speed; When the throttle is fully open, but the speed is not high; in the flat road, the throttle do not have to open, the engine issued a moderate load, speed and speed medium; on the highway, the engine may be full load, speed to maximum. In such a large number of complex work conditions, the requirements for the mixture can not be stereotyped. For example, in the idle and small load, the former requires the mixture must be very strong, the latter requires the concentration gradually thinning; in the medium load, in order to save fuel, but also requires carburetor supply fuel consumption of the smallest mixture; Under load, in order to allow the engine to send the maximum power, the carburetor is required to provide a rich mixture. In addition, if the car cold start, the requirements of a thicker mixture; acceleration requires carburetor in the throttle suddenly open, the additional supply of oil and so on. Gasoline engine Fuel Rail Pressure Sensor in the normal working conditions, in the small, medium load when the carburetor with the increase in load can be supplied by the thicker gradually become thinner mixture, under the full load and requires the mixture from dilute thick, only by the front The introduction of the simple carburetor can not be met.
In order to meet these requirements, in the modern carburetor is equipped with a series of mixed gas concentration compensation device. Such as the main fuel pump, idle speed, fuel economy, acceleration and start-up system to ensure that the gasoline engine in different working conditions, carburetor can supply the appropriate concentration of the mixture. Do not look at the carburetor little head, but the internal synthesis of so many systems, the structure becomes complicated. The seed guarantees that the carburetor can work normally, so it is very important for its regular maintenance. The main drawback of using a carburetor is that the distribution of the cylinder and the mixture is not ideal, affecting the power and economy of the engine, which is detrimental to the emission requirements. In recent years, countries in order to meet the environmental requirements, the use of direct fuel injection to replace the carburetor. The advantages of direct injection are high charge efficiency, high output power, uniform distribution of the mixture, according to changes in working conditions to provide the best composition of the mixture, low fuel consumption. The disadvantage is difficult ABS Sensor to arrange on the cylinder head, the manufacturing cost is high. According to the location of the injection can be divided into two kinds of in-cylinder injection and intake pipe injection, according to the control system, there are mechanical and electronic jet type (EFI) two categories.
From the 60's onwards, the electronic control of the gasoline injection system that is produced in Europe and the United States and other countries on the car engine gradually. In the EFI system, equipped with a precise control of the mixture composition of the regulator, and then installed on the three-way catalytic converter, so that the harmful components of the exhaust greatly reduced. The basic principle of the EFI system is through the sensor located in the various parts of the collected information feedback input to a microcomputer for processing, and issued by the order to control the mixture of air and fuel ratio, the supply of mixed Gas can adapt to the needs of the engine in a variety of conditions. For example, the computer according to the air flow sensor and the engine speed, and even the location of the throttle, cooling water temperature and air temperature sensors and other information collected to determine and calculate the fuel injection basis to determine the opening time of each injector, Oil, make it fuel.
The air flow sensor receives the information of the inhaled air flow; the starting switch receives the starting information; the throttle valve opens the throttle opening position information; the cooling is The water temperature sensor receives the water temperature information, and the air temperature sensor receives the temperature information. This information is fed back to Throttle Position Sensor the computer via circuit. In the EFI system, the most important parts in addition to the computer on the number of injectors. General engine Each cylinder has only one injector, located above the intake valve. The fuel is atomized by the injector and then mixed with the air from the intake pipe into the cylinder.
In order to meet the requirements of the emission regulations, some cars in the EFI system with a mixture of air conditioning system. It mainly uses an oxygen sensor in the trachea, which feeds back the information that the mixture is thin or thick. The computer re-instructs the injector according to the information to get the correct fuel injection. In the new generation of engine gasoline injection system has been combined with the ignition system, embodies the mixture of gas and ignition time of the optimal control, so that the performance of the engine greatly improved.