The cylinder block of the water-cooled engine and the upper crankcase are often integrally molded, called a cylinder block, a crankcase, which may also be called a cylinder block. The cylinder block is generally cast from gray cast iron. The cylindrical cavity in the upper part of the cylinder block is called a cylinder, and the lower part is a crankcase supporting the crankshaft. The inner cavity is a space for crankshaft movement. A plurality of reinforcing ribs, a cooling water jacket and a lubricating oil passage are cast inside the cylinder block.
The part of the lower part of the cylinder block for mounting the crankshaft is called the crankcase, and the crankcase is divided into the crankcase and the lower crankcase. The upper crankcase is integrally formed with the cylinder block, and the lower crankcase is used to store lubricating oil and close the upper crankcase, so it is also called an oil sump diagram. The oil sump is very stressed and is usually stamped from thin steel plates, the shape of which depends on the overall arrangement of the engine and the capacity of the oil. The oil pan is equipped with a stabilizing oil baffle to prevent the oil surface from fluctuating excessively when the car is turned. The bottom of the oil pan is also equipped with an oil drain screw. Usually, the oil plug is equipped with a permanent magnet to absorb the metal chips in the lubricating oil and reduce the wear of the engine. A gasket is placed between the upper and lower crankcase joint surfaces to prevent oil leakage.
The cylinder head is mounted on the upper surface of the cylinder block to seal the cylinder from the upper portion and constitute a combustion chamber. It is often in contact with high temperature and high pressure gas and is therefore subject to large thermal and mechanical loads. The cylinder head of the water-cooled engine is internally provided with a cooling water jacket, and the cooling water hole at the lower end surface of the cylinder head communicates with the cooling water hole of the cylinder block. The circulating water is used to cool a high temperature portion such as a combustion chamber.
The cylinder head is also equipped with inlet and exhaust valve seats, valve guide holes for installing inlet and exhaust valves, as well as intake and exhaust passages. The cylinder head of the gasoline engine is machined with a hole for installing a spark plug, and the cylinder head of the diesel engine is machined with a hole for installing the injector. A camshaft bearing bore is also formed in the cylinder head of the overhead camshaft engine for mounting the camshaft.