The invention discloses an adjustable intake and exhaust device of a marine medium-speed
diesel engine. The adjustable intake and exhaust device of the marine medium-speed
diesel engine comprises a compressor air supply
system, a pressurized air bypass
system and a
waste gas bypass
system, the compressor air supply system comprises a first electromagnetic switch valve, a three-way valve A, a second electromagnetic switch valve and a pressure-adjustable one-way valve, the pressurized air bypass system comprises a three-way valve B, a
pressure sensor, a first
electric control ball valve, a firstone-way valve and a three-way valve C, and the
waste gas bypass system comprises a second
electric control ball valve, a second one-way valve, a third one-way valve and a three-way valve E. Accordingto the adjustable intake and exhaust device of the marine medium-speed
diesel engine, the air supply amount can be increased, and the
black smoke emitting problem of the marine medium-speed diesel engine is solved; when a ship runs in cold regions such as an ice region, the
waste gas bypass system can prevent a
pressurizer from surging, and the running efficiency of the diesel engine is greatly improved; and meanwhile, when the diesel engine is loaded by 20%-80%, the pressurized air can be bypassed in real time according to the air-fuel ratio condition, and the partial load performance of thediesel engine is further improved.