Both gasoline engine and diesel engine belong to internal combustion engine. They convert chemical energy in the fuel into mechanical energy to drive the vehicle forward by pushing the piston in the cylinder to move back and forth after burning the fuel. Therefore, their working principles are basically the same.
As a daily fuel, diesel fuel has the highest energy density. Compared with gasoline, diesel oil is not easy to volatile, has a higher ignition point, and is not easy to be ignited or explode due to accidental circumstances. Because of the volatility and ignition point differences , engines using these two fuels have different ignition modes. Features of gasoline engine: small volume, light weight, low price, good starting performance, high speed at maximum power,small operation vibration and noise.
In a gasoline engine, after the mixture gas enters the cylinder, it is ignited by the spark plug near the end of compression. Therefore, gasoline engine needs a set of ignition system to control when to let the spark plug work. This system must precisely control the time of spark plug discharge and the size of spark energy, so as to ensure the normal operation of the gasoline engine. The fuel supply system and ignition system of the gasoline engine are the parts with high failure rate on the gasoline engine. In addition, due to the low ignition point of gasoline, the compression ratio of gasoline engine can not be too high to avoid the spontaneous combustion of oil and gas, so its thermal efficiency and economy are worse than that of diesel engine.
Characteristics of traditional diesel engine: better thermal efficiency and economy
The diesel engine uses compressed air to raise the air temperature, so that the air temperature exceeds the ignition point of diesel fuel. At the same time, diesel and diesel spray are mixed with air to ignite. Therefore, the diesel engine does not need ignition system. At the same time, the fuel supply system of diesel engine is relatively simple, so the reliability of diesel engine is better than that of gasoline engine.
The compression ratio of diesel engine is very high because it is not limited by deflagration and the need of diesel self ignition. Thermal efficiency and economy are better than gasoline engine. At the same time, under the same power, the torque of diesel engine is large, and the speed of maximum power is low.
However, due to the large working pressure of the diesel engine, the relevant parts are required to have high structural strength and rigidity, so the diesel engine is relatively bulky and bulky; the manufacturing accuracy of the fuel injection pump and nozzle of the diesel engine is required to be high, so the cost is high; in addition, the diesel engine works rough, with large vibration and noise; the diesel is not easy to evaporate, and it is difficult to start when in cold weather.
