Working Principle and Advantages of Six-Cylinder Diesel Engines

The variety of diesel engines is extensive today, including not only six-cylinder models but also four-cylinder, eight-cylinder, etc. More cylinders do not necessarily mean better performance; instead, the best diesel engine is the one that suits specific usage needs. For six-cylinder diesel engines, their working principle offers unique advantages. With continuous advancements in various aspects and ongoing refinements in details to enhance user experience, six-cylinder diesel engines have gained widespread customer recognition. Below, the editor from Dingbo Power Generator Manufacturer introduces the working principle and advantages of six-cylinder diesel engines:

1. Working Principle of Six-Cylinder Diesel Engines

Multi-cylinder diesel engines have two or more cylinders, with the piston-connecting rod mechanisms of each cylinder connected to a single crankshaft. Commonly used multi-cylinder diesel engines include 4-cylinder, 6-cylinder, 8-cylinder, 12-cylinder, and 16-cylinder models. Based on cylinder arrangement, they can be categorized into inline (straight) and V-type configurations, among others.

A six-cylinder diesel engine operates in a specific sequence determined by the number of cylinders and crankshaft arrangement. To ensure uniform operation and balance, each cylinder in a four-stroke diesel engine must complete one working cycle within two crankshaft revolutions (720°). Therefore, the ignition of cylinders must be evenly spaced at a specific angle. For a multi-cylinder diesel engine, the ignition interval angle is calculated as: θ = 720°/i (where i is the number of cylinders). For a six-cylinder diesel engine, this results in an ignition interval of 120° crankshaft angle. The crank throws are also spaced 120° apart. A typical firing order is 1-5-3-6-2-4 (e.g., in the 6135 series diesel engines). This sequence ensures good operational uniformity and balance, avoids consecutive ignition in adjacent cylinders, and benefits the performance of crankshaft main bearings.

2. Advantages of Six-Cylinder Diesel Engine Principles

Six-cylinder diesel engines are valued for their high power output and excellent fuel efficiency. While their working cycle shares similarities with gasoline engines—both undergo intake, compression, power, and exhaust strokes—the use of diesel fuel (which is more viscous, less volatile, and has a lower auto-ignition temperature) leads to differences in mixture formation and ignition methods.

The key distinction is that diesel engines rely on compression ignition rather than spark ignition. During operation, only air enters the cylinder. When compressed to the end of the compression stroke, the air reaches temperatures of 500-700°C and pressures of 40-50 atmospheres. As the piston approaches top dead center, a high-pressure fuel pump injects diesel into the cylinder at high pressure. The diesel atomizes into fine droplets, mixes with the high-temperature, high-pressure air, and auto-ignites. This combustion causes rapid expansion, generating a powerful force that drives the piston downward during the power stroke. At this stage, temperatures can reach 1900-2000°C, and pressures 60-100 atmospheres, resulting in substantial power output.

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