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Hansa diesel generator four-stroke diesel engine working principle
The working principle of the diesel generator set four-stroke diesel engine is as follows:
1. Intake process As shown in Figure 1-a, the piston moves from the top dead center to the bottom dead center. At this time, the intake valve is opened and the exhaust valve is closed under the action of the air distribution mechanism. As the internal volume of the piston cylinder increases, the pressure decreases, fresh air is continuously sucked into the cylinder through the air filter and the intake pipe. Due to the resistance of the air intake system, the gas pressure in the cylinder at the end of the intake is lower than the atmospheric pressure P0 (about 78 to 91 KPA) and the temperature is 320 to 340K.
2. Compression process As shown in Figure 1-b, the piston moves from the bottom dead center to the top dead center, at which point the exhaust valve closes. The internal volume of the cylinder is continuously reduced, the gas is compressed, and its temperature and pressure constantly increase. At the end of the compression, the gas pressure can reach 3~5MPA and the temperature can reach 750~1000K, creating the conditions for the evaporation, mixing and combustion of the diesel injected into the cylinder.
3, the work process shown in Figure 1-c shows, at the end of the compression process, the injector will spray diesel oil into the cylinder with a small oil mist, quickly evaporate under high temperature, high pressure and high velocity air flow, mixed with air, Mixture is formed. At high temperatures, it burns automatically and emits a lot of heat, which causes the gas temperature and pressure in the cylinder to rise sharply. The maximum pressure of the gas can reach 6~9MPA, and the maximum temperature can reach 1800~2000K. The high pressure gas expansion pushes the piston to move from the top dead center to the bottom dead center, so that the crankshaft rotates to do work externally. Since the injection and combustion will continue for a period of time, although the piston begins to move downwards, the injected fuel continues to burn and release heat, the pressure in the cylinder does not drop significantly, and the temperature in the cylinder changes as the piston moves down. And pressure gradually declined. At the end of the power stroke, the pressure is about 0.2~0.5 MPA.
4. Exhaust process As shown in Figure 1-d, after the work process is completed, the exhaust valve opens and the intake valve closes. The piston moves from bottom dead center to top dead center under the crankshaft. The burned exhaust gas leads the pressure difference and the piston's upward displacement, and is quickly discharged from the exhaust valve. Due to the resistance of the exhaust system, the exhaust pressure in the cylinder is slightly higher than the atmospheric pressure at the end of the exhaust. Residual exhaust gas pressure in the cylinder is about 0.105~0.12 MPA, and the temperature is about 700~900K.
After the piston passes through the above four consecutive processes, it completes a work cycle. When the exhaust process is over, the crankshaft of the diesel engine continues to rotate due to the inertia of the flywheel, and the above four processes are repeated. One after another work cycle is carried out so that the diesel engine continuously operates to drive the work machine to do work.