Unstable operation speed of marine diesel engine

1. Fault phenomenon When the marine diesel engine is in normal operation, the speed of the marine diesel engine is stable due to the automatic adjustment of the governor. The fluctuation value is only a few turns, and the volatility is within 0.5%. When the speed is unstable, there are two phenomena:

1 The ship's diesel engine is regularly high and low. It is commonly referred to as "carriage" and "gasp". This situation often occurs in the low-speed operating conditions of marine diesel engines.

2 The speed of the ship's diesel engine is irregularly high and low.

2. Reasons for the cause of instability of the ship's diesel engine are as follows:

(1) Reasons for oil supply system: There is air, water, gas resistance or water resistance in the fuel system, resulting in unstable oil supply; poor atomization of the injector, unstable injection, intermittent injection, or intermittent injection The fuel pump plunger oil outlet valve wears too much, the oil supply is unstable; the fuel injection pump rack is stuck, the injector needle valve is stuck; the injector spring, the oil discharge valve spring, the fuel injection pump spring break; the fuel injection pump oil The amount of adjustment of the ring gear is loose; the oil supply of each cylinder is seriously uneven.

(2) Reasons for speed control system: There is too much oil in the governor; the spring of the governor is deformed, broken or the rigidity is reduced; the governor fly iron stern sleeve is seriously worn; the governor moving parts are stuck or worn seriously.

(3) External causes: The diesel engine clutch with gearbox is poorly engaged and slipped; the working machinery load is seriously unstable.