Yancheng Shunyu Agriculture Machinery Co.,Ltd

Yancheng Shunyu Agriculture Machinery Co.,Ltd

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Yancheng Shunyu Agriculture Machinery Co.,Ltd

Address:Wengang South Road 59#, Yancheng City, Jiangsu Province, China





Diesel engine ventilation and pressurization

一 Four-stroke diesel engine ventilation process because the cylinder pressure and exhaust pipe pressure changes with the crank angle changes; into the exhaust valve flow cross-sectional area also changes with the crank angle changes, therefore, according to the characteristics of gas flow, The ventilation process is divided into several stages: *** Free exhaust phase: When the exhaust valve is opened, the cylinder pressure is much higher than the exhaust pipe pressure, exhaust pipe pressure and cylinder pressure ratio is less than the critical value, gas Flow for the supercritical flow, the cylinder exhaust gas flow through the exhaust valve at the minimum cross section. Cylinder pressure drops rapidly, exhaust pipe pressure increases. When the ratio of the exhaust pipe pressure to the cylinder pressure is greater than the critical pressure ratio, the gas flow is transferred to the subsonic flow stage. At some point, when the cylinder pressure is close to the exhaust pipe pressure, the free exhaust phase is ended.forced exhaust phase: the piston upstream of the cylinder exhaust forced forced into the exhaust pipe stage, that is forced exhaust phase. As the exhaust valve is delayed, the end of this stage can use the flow inertia of the exhaust gas in the exhaust pipe to continue to suck out the exhaust gas in the cylinder.Intake process: the intake valve is opened in advance, the exhaust pressure in the cylinder is lower than the intake pressure. The inlet flow has a certain inertia. The intake valve is closed and the kinetic energy of the gas can be converted into pressure energy so that the cylinder pressure is close to or slightly higher than the inlet pressure at the end of the intake air.Air valve stacking and combustion chamber Scavenging process: During air valve stacking, the intake pipe, the combustion chamber and the exhaust pipe are connected. When the pressure in the intake pipe is higher than the exhaust pipe pressure, the fresh air enters the cylinder And drive away the exhaust gas remaining in the combustion chamber into the exhaust pipe. In this way, it is advantageous to clean the residual exhaust gas, increase the amount of fresh air, and help reduce the temperature of the high temperature wall where the coolant of the combustion chamber is difficult to cool. However, it should be noted that: valve valve opening angle is not large like, because the intake valve is too early to open the exhaust gas into the intake pipe; exhaust valve closed too late, excessive scavenging air will reduce the turbine front Gas temperature, reducing the available energy of the turbocharger turbine. *** In the ventilation process, fresh air and exhaust gas is not mixed with. Therefore, the four-stroke diesel engine ventilation quality is high.

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