What are the engine oil supply methods

[WapCar] The engine needs to burn the mixed gas to do work, and we also call the method of mixing fuel and air as fuel supply. The fuel supply methods for automobile engines mainly include carburetor, single-point EFI, multi-point EFI and direct injection in cylinder. However, for today's vehicles, the main fuel supply methods are the latter two, and direct injection fuel supply methods are increasingly being used.

Carburetor

Carburetor is a mechanical device that mixes a certain proportion of gasoline with air under the action of the vacuum generated by the engine. As a precision mechanical device, the carburetor uses the kinetic energy of the inhaled air stream to atomize gasoline. Its important effect on the engine can be called the "heart" of the engine. The complete device should include a starting device, an idle speed device, a medium load device, a full load device, and an acceleration device. The carburetor will automatically proportion the corresponding concentration according to the requirements of the different working conditions of the engine, and output the corresponding amount of mixed gas. In order to make the mixed gas mixed evenly, the carburetor also has a fuel atomization Effect for the normal operation of the machine.

Working principle

It is difficult to find a new car equipped with a carburetor on the market today, but it has dominated for a long time. The principle of the carburetor is quite simple to say, it is a tube without any electronic control. The position of this tube is as shown in the picture, inserted on the intake pipe arm, one side is a small container for storing fuel, and the other side leads to the intake pipe. Through pure physical principles, the fuel in the small pipe can be automatically sucked into the intake pipe.

There are also such examples in life, put two paper strips near your mouth and blow air, the paper strips will not float to the two sides but gather together. This phenomenon occurs because the gas with a fast flow rate will produce low pressure, the pressure of the surrounding gas with a slow flow rate is greater, so the paper strips are pushed together. The carburetor of a car engine uses the same principle, the air pressure drops due to the high-speed flow of air in the intake pipe, thereby sucking out the fuel in the pipe. The faster the air flow rate, the lower the air pressure, and the more fuel that can be sucked out, which can be said that this is a simple and reliable device that relies purely on physical principles and has a lower cost.

Disadvantages of carburetor

The disadvantage of the carburetor is that the control is not precise enough, and it cannot quickly respond to changes in engine load and adjust the mixture concentration during normal driving. As a result, the engine is often in a state of insufficient combustion, and the content of harmful substances in the exhaust emissions cannot meet the increasingly stringent emission regulations, and at the same time, it will produce higher fuel consumption.

In addition, the carburetor is usually installed in front of the throttle valve, after the fuel is sucked out, it passes through the throttle valve and the intake manifold. It is inevitable that a part of the fuel will stick to the throttle valve and the manifold wall, which is very harmful to precise control of the fuel. Moreover, pure physical principles have higher requirements for air temperature and other conditions. When the temperature is low, it will seriously affect the mixing of fuel and air, this is why the previous cars need to warm up for a long time when they start in winter. So by the end of the 1990s, production was banned by the state, and it has now been completely eliminated.

Mechanical fuel injection

Because the carburetor cannot meet people's requirements for economy and environmental protection, people have developed a mechanical fuel injection device. The mechanical fuel injection system of the gasoline engine relies on the power of the engine crankshaft to drive the fuel pump to work, and the fuel is sprayed from the fuel injection nozzle when the fuel reaches a certain pressure.

Compared with the carburetor, the mechanical fuel injection device has a certain improvement in the accuracy of fuel control, but there are still some unsatisfactory places. Early mechanical fuel injection devices just simply replaced the carburetor, the position was still installed before the throttle, the fuel-air mixture still had to travel a long distance to reach the cylinder, which is the so-called single-point fuel injection.

Electronic fuel injection

With the development of science and technology, electronic fuel injection devices have appeared, divided into single-point EFI and multi-point EFI, the difference between the two lies in the number of fuel injection points. 它的Its working principle is to calculate the air intake volume of the cylinder through the air pressure sensor or air flow sensor installed in the intake pipe, and the data is transmitted to the engine electronic control unit (ECU), and then calculated by the ECU to control the solenoid valve to inject an appropriate amount of fuel .

Another major innovation is the use of multi-point fuel injection, fuel is no longer injected into the intake pipe and then delivered to each intake manifold. Instead, a fuel nozzle is installed at the end of the intake manifold of each cylinder, so that the distance traveled by the air-fuel mixture is greatly shortened, and the accuracy and efficiency of fuel injection are improved. In particular, the emergence of the electronic throttle allows the ECU to more comprehensively control the power output of the engine, further improving fuel economy.

In-cylinder direct injection

In today's increasingly stringent requirements for energy and environmental protection, even technology such as multi-point fuel injection can not meet people's requirements, so a more precise fuel injection technology was born, that is, direct injection technology. To put it simply, the in-cylinder direct injection technology is to install the injector of the original ordinary electronic injection system inside each cylinder, and the efficiency of the oil and gas mixing is improved to a higher level.

In-cylinder direct injection technology is to move the traditional injectors located at the intake manifold to in-cylinder injection. Its advantage is that it can more accurately control the fuel injection volume, and at the same time cooperate with the special intake vortex to make the mixture more fully Mixing to improve fuel efficiency. In addition, the atomized oil droplets injected in the cylinder by this direct injection technology can appropriately lower the temperature of the combustion chamber, which can match a higher compression ratio and further improve the efficiency of the engine.