The cylinder head of a diesel generator is also called a cylinder head. It is installed on the upper part of the cylinder block and is attached to the cylinder block using cylinder head bolts. Its function is to hermetically close the upper part of the cylinder and form the combustion chamber. It also has a cooling water jacket inside, and the cooling water holes on its end face are connected with the cooling water holes in the cylinder block so that the circulating water can be used to cool the high temperature parts of the combustion chamber.
The structural shape of the cylinder head varies depending on the shape of the diesel engine. Small diesel engines have integral or block structures, that is, the cylinder heads of all cylinders of the entire diesel engine (such as 4125, 12V150 diesel engines) or the cylinder heads of two or three cylinders (such as diesel engines 12V135, Cummins NTA). series diesel generators) Cast in one piece, it has the characteristics of compact structure and improved body rigidity. Large diesel engines use a single cylinder head (such as the Z12V190B diesel engine), which can be dismantled and replaced separately. The series is very versatile and offers good sealing performance.
The structure of the cylinder head of the four-stroke diesel engine is shown in Figure 2.17.
The cylinder head is generally made of high-strength cast iron in rough form, then machined. Structural cylinder head assembly of Cummins NTA series diesel engine. It has intake and exhaust passages, cooling water passages and lubricating oil passages inside. The cylinder head also has parts for installing fuel injectors, intake valves, exhaust valves, valve springs, seat seats.upape, minimal conduits and rocker chambers and threaded holes. .
The cylinder head is a double cylinder structure. There is a rocker chamber on the cylinder head and a gasket is used to seal the cover and the chamber to prevent oil leaks. A “wet” water jacket is installed in the hole where the fuel injector is installed. During operation, the cooling water circulating in the water jacket of the body flows through the gap between the outer wall of the water jacket and the cylinder head, so that the fuel injection nozzle is well cooled. In order to prevent water leakage, there is an annular groove on the upper part of the water jacket to install an O-shaped rubber sealing ring.
In order to To ensure the sealing of the cylinder head, a cylinder gasket is installed between the gasket surface of the cylinder head and the cylinder block. The cylinder seal is made of copper sheete sandwiched with asbestos, which has a certain degree of elasticity and strength. It is closely related to the prevention of air leakage, water leakage and oil leakage. Its thickness will also affect the compression ratio and operating performance of the diesel engine. Therefore, when using and repairing the diesel engine, attention should be paid to this. the cylinder gasket is in good condition and the original thickness should be used when replacing it.