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Introduction of diesel generator set's gas distribution mechanism and its working process

June 20, 2022
Diesel generator set structure fine, this top Bo power focus on the composition and working process of its gas distribution mechanism, according to the internal according to the type of diesel generator set internal combustion engine and valve configuration position of the different, gas distribution mechanism is also different. Four-stroke internal combustion engines have side-mounted (also called upright) and top-mounted (also called inverted) gas distribution mechanism.
1. Side-mounted gas distribution mechanism
Side-mounted gas distribution mechanism is installed on one side of the cylinder. It is mainly composed of intake valve, exhaust valve, valve spring, valve push rod, camshaft and timing gear, etc. The side-mounted valve is placed in the cylinder body.
The working process of side-mounted gas distribution mechanism is that the camshaft gear and crankshaft gear are meshed together according to certain marks in order to make the valve opening and closing timing match with each stroke of the internal combustion engine. When the crankshaft rotates, the camshaft is driven by the stop gear, and when the cam tip on the camshaft tops the push rod, the push rod rises and opens the valve, while the valve spring is compressed. When the cam tip is turned away from the push rod, the valve drops rapidly under the tension of the valve spring, and the valve is closed.
The advantage of the side-mounted distribution mechanism is that it is simple in structure, easy to form compression vortices, and is used more often in small internal combustion generating sets. The disadvantage is that the formed combustion chamber is not compact enough, poor anti-burst, more heat loss, intake and exhaust resistance, high HC emissions, this gas distribution technology is currently less used.
2. Overhead gas distribution mechanism
Top-mounted gas distribution mechanism mounted on the cylinder head. It has valve, valve spring, valve push rod, camshaft, tappet, rocker arm and other parts, because the valve top is facing downward, so it is also called the inverted distribution mechanism.
The working process of the top-mounted valve distribution mechanism: When the camshaft rotates, the cam cam tip lifts the push rod and tappet, the tappet tops the end of the rocker arm, which makes the rocker arm rotate around the shaft, and the other end of the rocker arm tops the valve foot to open the valve, and the spring is compressed while the valve is opened. When the cam tip is turned, the valve is closed by the spring force, and the rocker arm and tappet return to their original position. In an overhead valve engine, the valve is located at the top of the piston in the cylinder head.
The advantages of the overhead gas distribution mechanism are: it can form a more compact combustion chamber, reduce the intake and exhaust resistance, valve clearance adjustment is also convenient, because the top of the intake and exhaust valves just to the top of the piston, so there is no need for additional valve opening clearance, the combustion chamber can be designed to be small, heat loss can also be reduced, to ensure that in the case of high compression ratio, the height of the cylinder can be properly reduced, reducing the size of the engine . Therefore, most diesel engines use the top-mounted gas distribution mechanism. The main disadvantage of the top-mounted distribution mechanism is that the structure is more complex.
The function of the gas distribution mechanism is in accordance with the requirements of the internal combustion engine work cycle, to ensure that the mixture (or fresh air) in time to fill the cylinder, in the process of compression and expansion, to maintain the seal of the combustion chamber, and timely discharge of exhaust gas after combustion. This task, in the four-stroke internal combustion engine, is through the timely opening and closing of the intake and exhaust valves to achieve. In the two-stroke crankcase gas exchange in the internal combustion engine, the intake and exhaust is the use of piston movement, open and close the cylinder biscuit intake and exhaust holes to complete, so no special gas distribution mechanism.