Which is better, multi-point injection or direct injection? Ask the great god for help

Multi-point injection means that the injection process of gasoline fuel is in the intake manifold when the gasoline engine is working, and the control program sends out control instructions according to a specific time sequence, which is completed by the electronic injector. Multi-point injection is relative to single point injection. In the traditional gasoline engine, the carburetor is used to form a mixture of gasoline and air in the cylinder, which is ignited by the igniter during the compression stroke. Due to the different length and position of intake manifold, the amount and time of mixed oil and gas injected into each cylinder are also different, resulting in different working conditions of each cylinder.

Advantages and disadvantages of multi-point injection

Advantages:

1, the combustion efficiency is high, and the same displacement can release more power.

2. Sequential injection can be used, so the control of air-fuel ratio is more accurate than that of single-point injection, so the multi-point injection engine has better emissions and is more economical and fuel-efficient.

3. Strong self-purification ability. Due to the mixing of oil and gas in the intake manifold, there will inevitably be deposits on the pipe wall, but the intake manifold has stronger self-cleaning ability than the cylinder and is easier to clean manually.

Disadvantages:

1, which requires higher oil products, including engine oil.

2. The structure is complex, so the cost is high.

3. The engine power is relatively weak, because the location of oil-gas mixing is different. After multi-point injection of oil and gas mixture, the density is relatively straight.

Working principle of direct injection

In-cylinder direct injection (GDI) is a technology that directly injects fuel into the cylinder to mix with intake air. It can reduce fuel consumption and improve the dynamic performance of the engine.

Advantages and disadvantages of direct injection

Advantages:

1. The high-pressure fuel of direct injection engine is injected into the combustion chamber as a fine mist, which absorbs heat during evaporation and can cool the cylinder; Lean combustion can be realized, the combustion efficiency can be improved by 20%, the air intake is more than that of the traditional engine, the combustion is sufficient, and the generation of C0 is reduced.

2. The mixture concentration of in-cylinder direct injection engine is lower than that of ordinary EFI engine. If the mixture concentration is reduced, the economy will be improved. If you do the same work, the direct injection engine will save more fuel;

Advantages:

1. The high-pressure fuel of direct injection engine is injected into the combustion chamber as a fine mist, which absorbs heat during evaporation and can cool the cylinder; Lean combustion can be realized, the combustion efficiency can be improved by 20%, the air intake is more than that of the traditional engine, the combustion is sufficient, and the generation of C0 is reduced.

2. The mixture concentration of in-cylinder direct injection engine is lower than that of ordinary EFI engine. If the mixture concentration is reduced, the economy will be improved. If you do the same work, the direct injection engine will save more fuel;

Disadvantages:

1, the technical requirements are relatively high, and the technical difficulty of in-cylinder direct injection engine is the realization of "stratified combustion"

Difference between multi-point injection and direct injection

Multipoint injection:

Fuel is injected into the intake pipe of each cylinder of the engine, and the fuel forms mixed gas in the intake pipe. Compared with single-point EFI, this engine has higher combustion efficiency and can release more power under the same displacement. The technology is relatively mature and widely used.

Direct injection:

Direct injection is the most popular technology in recent years. This technology, originally used in diesel engines, has been widely used in gasoline engines. Fuel is directly injected into the cylinder in the engine to form combustible mixture with the air in the cylinder, which is more economical, more environmentally friendly and has obvious advantages. However, the requirements for the strength of the cylinder block and the nozzle of the cooling system are very high, and it is rarely used now.