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What is the 4 stroke Outboards?
Dec 13, 2017

What is the 4 stroke Outboards?

In the 4 stroke engine, the crankcase does not hold the combustible mixture, does not set the intake port, and does not install the intake mechanism. The crankcase of the engine is equipped with crankshaft connecting rod assembly, timing chain and speed changing mechanism. The inner cavity is equipped with oil, and the parts of the friction pair are splashed and lubricated by rotating and rotating parts such as crank shaft. The intake and exhaust ports of the 4 stroke engine are usually installed on the cylinder head, and the cylinder is only a light hole. There is a rectangular channel between the two cylinder cylinders of the twin cylinder engine, and it can pass the timing chain and install the tension mechanism.

4 stroke engine is a very complex parts (especially the type of OHV mechanism), the cylinder cover is provided with an air inlet and an air outlet valve, valve guide, airway, channel, valve springs, valve rocker arm, cam shaft and its driving mechanism. In order to lubricate the parts installed on the cylinder head, the inner cavity of the cylinder head is equipped with a special oil channel.

The crankcase of the 4 stroke engine is almost connected with the cylinder part. It ensures the good sealing performance by using the effective bonding of piston ring and cylinder wall and lubricating oil film, and prevents gas leakage in cylinder. When the piston runs downward, the crankcase is in a positive pressure state. When the piston runs up to the top point, the crankcase is in a negative pressure state, and the air pressure in the crankcase is always between positive pressure and negative pressure. When gasoline engine works, there will be more or less a small amount of combustible mixture and exhaust gas running through the tiny gap of piston ring and cylinder wall into the crankcase, so the air pressure in crankcase is slightly higher than atmospheric pressure. When the engine is extinguished and cooled, the gas that moves into the crankcase will be condensed into water or waste oil. If it is not discharged in time, it will seriously affect the normal operation of the engine. Therefore, at the upper entrance of the four stroke crankcase, a "ventilator" which is connected with the atmosphere is specially set up to ensure the internal and external pressure balance. In order to reduce the pollution of the oil vapor in the crankcase to the air environment, the modern engine adopts closed crankcase ventilation system, and a special hose is applied to the air filter to make the unburned fuel burn again.


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Add.:No.126, ChangDa Road, Yuhang economic and Technological Development Zone, Yuhang, Hangzhou

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