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Cause Analysis and Elimination Method of Diesel Generator Set's Speed ​​Unsteady

May 17, 2022
The unstable speed of diesel generator is also called "travel car" or "surge car". Such failure will not only affect the actual power supply effect of the diesel generator set, but also reduce the life of the parts of the diesel generator, resulting in the final use of the diesel generator. Reduced lifespan. Generator manufacturer-JUNVOCH warm reminder: The main reasons for the unstable speed of diesel generator sets are oil circuit failure, governor failure and fuel injection pump failure. The following JUNVOCH will analyze them for you one by one.
1. Oil circuit failure
1. 1 The low-pressure oil circuit is blocked and the oil supply is not smooth. The elimination method is to clean and unblock the low-pressure oil circuit.
1. 2 The fuel tank is insufficient or the vent hole of the fuel tank cap is blocked, causing insufficient fuel supply. Remedy Add enough fuel and clear the vent hole of the fuel tank cap.
1.3 Oil pipe cracking, loose pipe joints, etc. cause the low-pressure oil circuit to enter the air. In addition, the wear of the multi-cylinder diesel engine hand oil pump can also easily cause the oil circuit to enter the air. The solution is to replace the oil pipe and hand oil pump, and tighten the pipe joints.
1.4 The sealing performance of the fuel injection pump outlet valve is deteriorated or the positioning screw is loose. Remedy: Grind the oil outlet valve and tighten the positioning screw.
1.5 The fuel injector is unstable. Remedy: replace the injector needle valve coupler.
2. The governor failure
1. The elasticity of the speed regulating spring is weakened. Insufficient spring force will reduce the speed control sensitivity of the governor, and the stable range of the diesel engine speed will increase, fluctuating high and low. At this time, the speed regulating spring should be replaced.
2. Excessive wear of the oil pump oil volume adjustment arm and the fork groove of the speed control lever, the conical surface of the drive plate and the thrust plate, etc., will cause the adjustment effect of the governor to lag, resulting in "travelling". At this time, the worn parts should be replaced to restore the normal fit clearance.
3. The internal lubrication of the governor is poor, or the oil in the governor is too dirty or thick, or the surface of the moving parts is damaged, which causes the movement of the moving parts to be blocked, and the speed regulation function lags behind, resulting in the unstable speed of the diesel engine. The method of elimination is to clean the inside of the governor with diesel oil, replace the oil in the governor, and repair or replace the damaged parts.
3. Failure of the fuel injection pump
The wear of the plunger pair, the oil outlet valve pair and the wheel of the sub-pump of the multi-cylinder diesel engine causes the inconsistent oil supply pressure of each cylinder, and the improper adjustment of the fuel injection pump will cause the inconsistent fuel supply. At this time, it should be readjusted on the test bench. In addition, the cylinder head gasket of a multi-cylinder diesel engine is burned, the valve seal is not good, the piston ring is excessively worn, etc., so that the cylinder is poorly compressed or does not work, which will make the diesel engine speed unstable. The solution is to replace the cylinder head gasket, piston rings and ground valves.