AILESEN(CHANGZHOU)POWER TECHNOLOGY CO.,LTD

Marine diesel engines have high thermal efficiency, good economy, easy starting, and great adaptability to various types of ships. They were quickly used as ship propulsion power after they came out. By the 1950s, diesel engines had almost completely replaced steam engines in newly constructed ships. Marine diesel engines have become the main power of civil ships, small and medium-sized ships and conventional submarines. Marine diesel engines can be divided into main engines and auxiliary engines according to their roles in ships. The main engine is used as the propulsion power of the ship, and the auxiliary engine is used to drive the generator, air compressor or water pump.

Marine diesel engines are generally divided into high-speed, medium-speed and low-speed diesel engines. The main performance indicators of the three types of diesel engines are listed in the table.

The fuel valve test device, pneumatic high-pressure pump, and manual high-pressure pump are the three essential parts of the diesel engine.

Marine main engines work under full load conditions most of the time, and sometimes under variable load conditions. Ships often sail in turbulence, so marine diesel engines should be able to work reliably under the conditions of trim 15°～25° and heel 15°～35°. Most ships use supercharged diesel engines, and low-power non-supercharged diesel engines are only used on small boats. Low-speed diesel engines are mostly two-stroke engines, medium-speed diesel engines are mostly four-stroke engines, and high-speed diesel engines have both. The scavenging forms of marine two-stroke diesel engines include backflow scavenging, port-valve DC scavenging and opposed piston 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.

Directly drive the propeller, in order to make the propeller have high propulsion efficiency, a lower speed is required. Medium and high-speed diesel engines drive propellers through gear reduction boxes. Gear boxes are generally equipped with a reverse 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 also realize electric transmission through generator-motor-propeller. When high power is required, multiple engines can be used in parallel, and only one main engine can be used when sailing at low speeds, thereby improving operating economy and reliability. When two main engines are installed on the same ship, they are divided into left and right engines according to the installation position and the steering of the propeller.