Introduction of marine diesel engine parts The difference between high, medium and low speed marine diesel engines

General marine engines belong to the category of low-speed engines, and the speed of the engine is generally below 800rpm (except for special speedboats), because the marine engine needs to be matched with the propeller, and the speed of the propeller is about 600-800rpm. Considering the matching efficiency value, too high engine speed is not helpful for this; other large cargo ships or cruise ships use heavy oil (the worst oil), which are generally two-stroke low-speed engines. Of course, there are also High-power four-stroke medium-speed engine, medium-speed engine is generally used as an auxiliary engine on ships for power generation and other uses.

methods and steps

1. The difference between high, medium and low speed marine diesel engines:

The marine engine speed range above 3000 rpm is a high-speed engine, 1500-3000 is a medium-speed engine, and below 1500 is a low-speed engine.

2. Most low-speed diesel engines are two-stroke engines, most medium-speed diesel engines are four-stroke engines, and high-speed diesel engines have both. The scavenging forms of marine two-stroke diesel engines include return scavenging, air-port-valve direct-current scavenging and opposed-piston air-port scavenging. High-power medium and low-speed diesel engines widely use heavy oil as fuel, and high-speed diesel engines still mostly use light diesel.

3. The low-speed diesel engine directly drives the propeller. In order to make the propeller have high propulsion efficiency, a lower speed is required. Medium and high-speed diesel engines drive the propeller through a gear reduction box, and the gearbox is generally equipped with a reversing mechanism to achieve propeller reversal, but low-speed diesel engines and some medium-speed diesel engines can reverse themselves. Medium and high-speed diesel engines are also electrically driven by generators-motors-propellers.