Typical Failure Analysis of CCEC Cummins K-19 Diesel Generator Set.
1 Performance of typical failure.
1.1 the coolant does not circulate.
At work often encounter coolant loop: not have large cycle, no small cycle, or with minor cycle without large cycle, this makes the unit appear cylinder temperature rising fast, high oil temperature rise caused by the sudden stop wait for a phenomenon, directly affect the safe use of the unit.
1.2 Low oil pressure.
The low oil pressure can cause the lubrication of the transmission parts of the unit. If the oil road is blocked, there will be a large gap between the cylinder, the cylinder and the bearing, which will directly affect the normal use of the unit.
1.3 The engine makes noise.
There are many kinds of engine noise, and if it is not judged, it will cause the strain of the transmission, which will cause the main bearing or piston to be damaged, which will have serious consequences.
- Reasons analysis
2.1. The cooling liquid does not circulate.
The main problem of cooling fluid temperature in cooling system is as follows:
(1) the cooling liquid level is too low or not in accordance with the regulations.Liquid level is too low can directly cause the coolant temperature cooling fluid circulation, cooling fluid according to regulations is 50% antifreeze + 50% + DCA4 demineralized water, if do not conform to the rules will cause pipeline jam, rust inside the wall, make the cooling fluid can’t normal cycle.
(2) the radiator fin is blocked or damaged.The heat dissipation fan does not work or the heat sink is blocked, so that the cooling liquid temperature can not fall down, the heat sink rust, causing leakage phenomenon, can also cause the circulation bad.
(3) air is mixed in the cooling system so that the pipeline is not smooth, and the damage of the suction valve and exhaust valve on the expansion tank can also directly affect the circulation.It is important to check whether their pressure value is in accordance with the regulation, the suction pressure is l0kPa, the exhaust pressure is 40kPa, and whether the exhaust pipe is unblocked is also an important reason for the circulation.
(4) thermostat failure.In order to control the temperature of the combustion chamber, a thermostat is installed.Thermostat must be in the specified temperature (82 ℃) fully open help small cycle, when there is no thermostat, cooling fluid always maintain its circulating temperature, but also easy to produce low temperature alarm.
(5) water pump failure.Check whether the water pump function is good, KD 997870 I machine coolant piping not cycle, when the check to the water pump, found the water pump drive gear shaft wear limit, the pump has no effect, replace the normal only after cycle.
2.2. Low oil pressure.
According to the analysis of the oil flow chart above, the low oil pressure is mainly related to the following aspects:
(1) lubricating system: oil filter is dirty;The oil suction pipe is blocked;The oil pressure regulator fails.
(2) cooling system: the oil cooler is blocked;The outer space of the radiator core is blocked.
(3) maintenance: engine overload;Oil needs to be replaced.
(4) mechanical adjustment and repair;Improper bearing clearance;Engine needs overhaul;Damaged main bearing or connecting rod bearing.
For example: taiyuan car depot generators KD 997868 “181”, because of the low oil pressure were delivered after careful examination revealed oil are no problem, and the oil surface by adjusting oil pressure returned to normal after the pressure valve, other power car has had the similar situation also.KD 997998 has had the adverse effect of pressure pump, and the oil pressure returned to normal after overhaul.Attendant is required special attention to the maintenance of the unit, the oil needs to be changed in time (250 h), oil filter to correct use, as long as the right, in accordance with the maintenance method to do, to guarantee the normal use of the unit.
2.3 noise
The noise produced by the engine is normal and abnormal. To determine whether the noise is normal, it is necessary to determine which accessories are caused by the noise.Based on experience, using a simple stethoscope helps to locate the engine noise.
2.3.1 noise location
(1) if the noise changes with the crankshaft speed (engine speed), the noise may be related to the crankshaft, connecting rod and piston pin.
(2) the noise may be related to the valve rotating part if the noise is changed with the camshaft speed.
2.3.2. Judgment method
(1) main bearing noise: the noise generated by the loose main bearing can be heard when the engine is loaded, and its sound is loud and dull;If all the main bearings are loose, a loud “click” will be heard, and the “click-click” sound is regular and varies with the speed.When the engine is loaded or reloaded, the noise is the loudest, and the noise of the percussion is duller than the noise produced by the connecting rod, which can reduce the oil pressure.
(2) the noise of connecting rod bearing: excessive clearance of connecting rod may cause various noises of the engine, and the idle speed and the percussion noise in the load condition are different.When bearing became loose, the pounding noise May 9 piston or loose piston pin noise mixed together and the noise increases with the increase of the rotational speed of engine, when these sounds will appear under the condition of lower engine oil pressure.
(3) piston noise: piston pin loosening generates a double-click on the noise, usually is likely to hear when the engine idle speed is running, when the cylinder injector plunger is under pressure, the sound will be more obvious.
- Suggestions
(1) to solve the problem of cooling liquid, it should be done: correctly judge the fault location;In order to ensure that the coolant is strictly observed, the coolant of each train is tested and recorded every 5, 15 and 25.Ensure that the liquid level of the coolant reaches the standard, and each train is equipped with a storage box;Ensure that the utilization rate of each sensor reaches 100%. In particular, it is necessary to test the temperature sensor and the water temperature sensor.Enhance the safety awareness of flight attendants and ensure inspection records every half hour.
(2) for the problem of low oil pressure, it should be noted that: 15W / 4OCD oil is used in accordance with the regulations, and before starting the machine, check whether the oil level meets the standard, (between the two scales of the oil gauge);Proper use of oil filter, the oil should be added before replacement, the sealing ring should be cleaned by oil, and the filter element should be tightened to ensure safe use.Correct use of the unit, absolutely cannot overload, forbid overload operation;Change the oil (250h) on time, and should have the quality inspection and supervision to make the original record.
(3) use the simple stethoscope to correctly judge the source of the noise, use it correctly, and judge in time. (the simple stethoscope can be made with the core screwdriver.)Maintenance group should make regular check for the unit, timely maintenance, and every six months to a unit valve clearance adjustment and fuel injection nozzle calibration, judge the large fault contact manufacturer to repair processing.