Cylinder Liner of Air-cooled Diesel Generator

An air-cooled diesel generator is an internal combustion engine that uses diesel fuel to convert the heat energy released by fuel combustion into electrical or mechanical energy. The air-cooled diesel generator is easy to start, runs economically, and has strong adaptability to the environment, which is welcomed by a large number of users.

The manufacturing process requirements for air-cooled diesel engines are higher than those for water-cooled diesel engines, and there are also high requirements for the heat resistance, wear resistance, and coefficient of expansion of the materials used. In this article, we will learn together the three major characteristics of cylinder liners in air-cooled diesel engines.

(1) Requirements for cylinder liners

The working conditions of the cylinder liner of an air-cooled diesel generator are extremely harsh. It not only directly bears the effects of high temperature and pressure, but also bears the pressure and friction of the reciprocating motion of the piston, as well as the temperature difference between the inner and outer walls of the cylinder. Therefore, the cylinder liner is one of the main components that directly affects the reliability and service life of diesel engines.

According to the usage characteristics of air-cooled diesel generators, the cylinder liner must meet the following requirements:

1. Having sufficient stiffness and strength, with small overall deformation, able to withstand large thermal and mechanical loads. 2. The inner wall of the cylinder liner should have sufficient wear resistance and corrosion resistance. 3. Has good heat dissipation ability and resistance to thermal deformation. 4. It should have good process performance. 5. Has high precision to ensure good sealing performance. 6. The resistance of the cylinder liner heat sink to the cooling air should be small.

(2) Structure of cylinder liner

Taking the cylinder liner of the DEUTZ FL513 series diesel generator as an example, the following is a brief explanation. The cylinder liner of the air-cooled Deutz diesel engine adopts an independent single body structure, made of high phosphorus alloy cast iron material. The upper part is cast with heat dissipation fins, and the lower outer circle has a cylindrical surface. The lower positioning stop that connects with the bottom hole of the cylinder liner of the machine body is φ 138.84mm. The inner wall of the cylinder liner is honed with mesh patterns, which has good wear resistance and high strength.

In order to meet the high-performance requirements of diesel engines, the working surface of the cylinder liner needs to undergo honing or surface phosphating treatment after precision boring and grinding. Honing further improves the accuracy of the inner hole of the cylinder liner and forms a 60 ° mesh pattern for lubrication. The inner surface of the cylinder liner after phosphating treatment forms a large number of uniformly distributed voids, forming numerous oil accumulation voids. This treatment method on the inner surface of the cylinder liner effectively improves lubrication conditions, giving it high wear resistance and operational reliability.

Special reminder: The requirements for piston ring material are different between honing cylinder liners and phosphating cylinder liners. When repairing and replacing piston rings, attention should be paid to this point.

(3) Sealing between cylinder liner and body

The cylinder liner is fastened to the engine body together with three cylinder head bolts and the cylinder head. The sealing between the cylinder liner and the bottom hole of the cylinder liner installation is achieved through a 0-shaped rubber sealing ring and a thin steel ring (middle ring), as shown in the following figure. The size of the O-ring seal is ▽ 130.3mm × 3.15mm; The thickness of the intermediate ring is 0.25mm and 0.5mm.

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