Formation Characteristics of Diesel Engine Mixture

The length of the ignition delay period of a diesel engine will significantly affect the amount of fuel injection and pre mixed air during the ignition delay period, thereby affecting the combustion properties, power, economy, emission characteristics, and noise vibration of the diesel engine, which must be precisely controlled.

The mixture of diesel generators is formed inside the cylinder. Due to the difference between diesel engines and gasoline engines, the viscosity and evaporation of the diesel used are poor, and the natural temperature is lower than that of gasoline. It cannot form a uniform mixture with air outside the cylinder through the mixture formation device like gasoline engines do, and high-pressure injection is required. At the end of the compression stroke of a diesel engine, diesel is pressurized by the fuel injection pump and injected into the combustion chamber through the injector to mix with air. During the period from the start to the end of fuel injection, the fuel injected into the cylinder undergoes physical and chemical processes such as heating, oxidation, etc., and burns. However, due to the time required for fuel injection, fuel injection continues at this time, resulting in a mixture of one side burning and the other side injecting, making it difficult to form a uniform mixture. The combustion process of diesel engines is very complex, and it is usually divided into four stages: ignition delay period (also known as ignition delay period), rapid combustion period, and slow combustion period.

The formation of diesel engine mixture has the following characteristics:

a. The formation time of the mixture is extremely short, far less than that of a gasoline engine. The formation of the gasoline engine mixture from the intake stroke to the compression stroke accounts for about 360 ° of the crankshaft angle, while the diesel engine only accounts for 18 ° -35 ° of the crankshaft angle, which is about 1/24-1/10 of the gasoline engine

b. Diesel has high viscosity and poor volatility, making it difficult to ensure complete contact between all fuel molecules and air, which affects the quality of the mixture. Therefore, the brand of diesel must be selected according to the season or local temperature.

c. From the start of fuel injection to the start of combustion, it only takes 0.001-0.004s (seconds), so the mixing of air and diesel occurs simultaneously with the combustion process. Burning the exhaust gas in this way will affect the mixture of diesel and air, which is not conducive to the formation of the mixture. When the fuel injection amount of a diesel engine is high (under heavy load), it is easy to produce soot. Diesel engines have complex structures, high quality, good materials used, high processing accuracy, and high manufacturing costs.

Fault diagnosis and treatment methods for excessive fuel mixture in diesel engines

(1) The air filter is too dirty and clogged. Clean or replace the air filter element.

(2) The exhaust gas turbocharger system has insufficient boost intensity. Inspect the exhaust gas turbocharger system.

(3) The fuel injector injection pressure is set too low. Increase the fuel injection pressure.

(4) The fuel supply of the fuel injection pump is too high. Reduce the fuel supply of the fuel injection pump.

Failure diagnosis method

(1) Firstly, check if the air filter is too dirty or clogged;

(2) If there is no blockage, check the exhaust turbocharger system.

(3) If the boosting system is normal, check whether the fuel injector injection pressure is too low.

(4) The fuel supply of the final fuel injection pump is too high.

An excessively rich mixture in a diesel engine can cause the diesel engine to be difficult to start, resulting in severe carbon buildup in the combustion chamber, black smoke or explosions in the exhaust pipe, engine failure, poor acceleration, insufficient power, and increased fuel consumption. Diesel engine mixture gas lean: The phenomenon of engine shaking makes it difficult to start, and in severe cases, it can cause poor starting power and acceleration.

Dingbo Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to sales@dieselgeneratortech.com we will pay highly attention on your question.