Generally, the following principles are followed:
1) When there is an abnormal phenomenon in the operation of the diesel engine, you can use the comprehensive judgment of which part or which system produces the fault by seeing, hearing, feeling and smelling.
"See" ---- to observe the reading of the instrument, exhaust smoke and water, oil changes;
"Listen" ---- with a long and thin metal rod or wooden handle driver as "*" touch the diesel engine surface corresponding parts of the "auschology" shipment of sound and its changes:
"Touch" ---- by finger feeling check the valve mechanism and other parts of the working condition and diesel engine vibration;
"Smell" ---- by the sense of smell, smell out the diesel engine has abnormal smell
2) When the diesel engine fails suddenly or the cause of the failure has been determined, and the failure will affect the normal operation of the diesel engine, it should be stopped in time for inspection. For the fault that cannot be found out immediately, the diesel engine can be run at low speed without load first, and then observe and analyze to find out the cause, so as to avoid bigger accidents.
3) When it is judged to be a major fault or the diesel engine suddenly stops by itself, it should be disassembled, inspected and maintained in time.
4) Each failure, especially major failure causes and troubleshooting methods, should be recorded in the operation book of the diesel engine for reference in the next maintenance.
The common faults and troubleshooting methods of diesel engines listed in this chapter are for the reference of operators only. In the actual work, should be based on the specific conditions and practical experience of the time and local flexible grasp, find out the internal and external causes of the failure, "appropriate medicine" timely elimination.
I. Common failures in the use of diesel engines
1. Failure of diesel engine to start
No. Fault features and troubleshooting methods
1. Failure of fuel system: the diesel engine is driven by the starting motor and there is no return oil in the non-ignition return pipe
(1) There is good air in the fuel system
(2) Fuel pipeline is blocked
(3) The fuel filter is blocked
(4) The oil pump does not supply oil or the oil supply is intermittent
(5) There is little oil injection, no oil injection or no atomization fault characteristics and causes
(6) Position of governor control handle of fuel injection pump
1. Check whether the fuel pipeline connector is loose and remove air from the fuel system. First unscrew the vent screw on the injector filter, and pump it clean by hand until it overflows.
Tighten the vent screw when there are no bubbles in the fuel. Then pump oil, when there is oil return in the oil return pipe, then tighten the hand pump and loosen the nut of the high pressure pipe at the injector end, and consume several times after burning, so that each cylinder injector is filled with fuel.
2. Check whether the guard road is unblocked.
3. Clean the filter or replace the filter element.
4. Check whether the inlet pipe leaks air and whether the network of the inlet pipe joint is blocked. If no oil is supplied after removal, check the pipeline and oil pump.
5. Remove the injector, connect it to the high pressure oil pump, consume the plunger spring of the fuel pump, observe the spray condition and remove and wash it if necessary, check and adjust the scope of the injection pressure force on the injector degree test table or replace the oil injector couple.
Elimination method
When starting, the handle position should be pushed to the no-load, rotating speed of 700-900r/min or so.
2 Fault of electric starting system:
(1) Circuit wiring error or poor contact
(2) Battery power is insufficient
(3) There is no contact or bad contact between the starting motor and the commutator
Check whether the wiring is correct and reliable. Use the battery with sufficient power or increase the battery in parallel. Use the dressing or replacement of the carbon brush, clean the reversing surface with wood sand paper, and blow clean or adjust the pressure of the brush spring.
Insufficient compression pressure in the cylinder: fuel injection is normal but there is fuel in the exhaust pipe without ignition
(1) Excessive wear of piston ring or cylinder line
(2) Valve leakage
(3) The gas storage gap or the combustor volume is too large
Replace the piston ring, depending on the wear of the replacement cylinder liner check valve clearance, valve spring, valve guide and valve seat sealing, sealing should be repaired and grinding to check whether the piston belongs to the model, if necessary, should measure the gas clearance or combustion chamber volume.
4. The front Angle of the fuel injection arm is too early or too late, even 180°;
Diesel injection does not fire or fire and stop
Check whether the cutting line on the joint plate of the fuel injection pump transmission shaft is correct or slack. If it does not meet the requirements, it should be remeasured
5. If the valve phase is not correct, check the valve phase according to the method in Chapter 2
6. If the ambient temperature is too low and the starting time is long, the ignition is not triggered. Summarize the actual ambient temperature and take corresponding low-temperature starting measures
2. Diesel engine underpower
Fault features and troubleshooting methods
1, fuel system failure: increase the throttle power or speed is still not high
(1) Fuel pipeline and fuel filter enter the air or are blocked
(2) Insufficient oil supply for fuel injection pump
(3) Poor atomization of injector or low injection pressure
Remove the air or replace the core of the fuel filter according to the above method. Inspect, repair or replace the coupling parts. Spray, observe or adjust the fuel injection pressure, and check the coupling parts of the fuel injection nozzle or replace it.
Two, diesel engine common faults and troubleshooting methods
1. Fault of inlet and discharge system: higher discharge temperature and poorer smoke color than normal
(1) The air filter is blocked
(2) The exhaust pipe is blocked or the pipe is too long, the turning radius is too small and the elbow is too much
2, clean the air filter core or remove the dust on the paper filter element, if necessary, should be replaced: and check whether the oil level is normal.
Remove carbon accumulation in exhaust pipe; No more than three exhaust nozzles can be reloaded and have a large enough exhaust root surface.
3. Fuel injection advance Angle or inlet and exhaust phase change: the speed performance of each gear becomes worse
Check whether the two screws at the fuel injection pump drive shaft are loose, and correct the injection advance Angle, tighten and check the valve phase and valve clearance if necessary.
4, diesel engine overheating, environmental temperature is too high: oil and cooling water temperature is very high, the discharge temperature is also greatly increased check cooler and radiator, remove scale; Check whether the pipe diameter is too small. If the ambient temperature is too high, improve ventilation and temporarily strengthen cooling measures
5, the cylinder head component failure: at this time not only insufficient power, performance decline, and leakage, intake pipe smoke there is abnormal knocking sound and other phenomena.
(1) Air leakage in the joint surface of the cylinder head and the body, and there is a stream of air rushing out of the gasket when changing speed
(2) Air leakage at inlet and exhaust valves
(3) Valve spring damage
(4) Valve clearance is not correct
(5) the fuel injector hole leakage or its copper gasket damage;
Piston ring stuck, valve rod biting cylinder pressure
Tighten the big nut or replace the cylinder liner according to the specified torque. If necessary, repair and scrape the loosening of the big stud nut of the joint surface cylinder head or the damage of the cushion. Remove the inlet and exhaust valves and repair and grind;
Valve and valve seat mating surface; Replace the damaged spring rectifying valve; Clearance to the specified value; Disassemble, repair, clean and replace the damaged parts.
6, connecting rod bearing and crankshaft connecting rod journal surface bite hair:
Remove the side cover of the diesel engine, check the lateral clearance of the big head of the connecting rod, and see whether the big head of the connecting rod can move back and forth. If it can't move, it means that the hair is bitten. It is necessary to repair the journal and replace the connecting rod bearing bush.
7, turbo fault: speed decline; Reduced intake pressure, air leakage or abnormal sound, etc
(1) supercharger bearing wear, rotor friction
(2) The inlet pipe of the compressor and turbine is contaminated, blocked or leaking, and the bearing should be repaired and replaced to clean the inlet, shell and impeller; Tighten the joint surface nut, etc
8, diesel engine running abnormal noise fault characteristics and causes, elimination methods
(1) Premature oil injection time: rhythmically clear metal knocking sound is emitted in the cylinder
See Chapter 2 for the method of adjusting injection advance Angle
(2) Oil injection time is too late: a low and unclear knocking sound is emitted in the cylinder
(3) the piston pin is too loose with the connecting rod small head bushing hole: there is a light and sharp sound when running, this sound is especially clear when running at constant speed. Replace the connecting rod small head bushing to make it within the specified clearance range
(4) the gap between the piston and the cylinder liner is too large: when running, the sound of collision is heard on the outer wall of the cylinder block. When the speed increases, the sound of collision is intensified. Replace the piston or replace the cylinder liner according to the wear condition
(5) Connecting rod bearing wear so that the gap is too large: when running, parts of the crankcase hear the sound of collision, suddenly reduce the speed of heavy and powerful collision can be heard, the removal of bearing, if necessary, should be replace
(6) The radial clearance of the crankshaft rolling main bearing is too small: a particularly sharp sound is emitted in operation, and the sound is more clear when the throttle is increased; Radial clearance of crankshaft rolling main bearing is too large: "huo Huo" sound is emitted during operation. Check the rolling main bearing with sound and replace it if necessary
(7) The front and rear thrust bearings of the crankshaft are worn, and the axial clearance is too large to lead to the crankshaft swimming back and forth: when the diesel engine is rotating, the collision sound of the crankshaft swimming back and forth is heard
Check the wear degree of axial clearance and thrust bearing and replace it if necessary
(8) The valve spring is broken, the tappet is bent, and the push rod sleeve is worn: a slight rhythmic tapping sound is issued throughout the cylinder, the damaged parts are replaced, and the valve clearance is adjusted according to the method introduced in Chapter 2
(9) Valve touching piston: Heavy, even and rhythmical tapping sound is emitted from the cylinder head during operation. The nut of the cylinder head cover shell is gently held with fingers and feels collision. Remove the cylinder head cover shell, check the cause of collision, adjust the valve clearance, and check whether the piston model is adjusted incorrectly if necessary. The valve pit can be properly dug deep or a 0.2mm or 0.40mm thick copper gasket with the same shape as the bottom of the cylinder can be added
(10) Transmission gear wear and clearance is too large: abnormal sound is sent out at the front cover plate. When the speed drops suddenly, the sound of impact can be heard to adjust the backlash and replace the gear according to the wear situation
(11) There is no oil between the rocker arm adjusting screw and the spherical seat of the push rod. The "squeak" sound of dry friction is heard at the cylinder head. The cylinder head cover is removed and the oil is added
(12) The inlet and exhaust valve clearance is too large: when the cylinder head hears a larger sound with a rhythm, re-check the valve clearance, as shown in chapter 2
(13) Turbocharger operation when there is abnormal collision sound disassembly bearing wear, impeller blade is bent, the same amount of measurement of the main clearance and adjustment and replacement of damaged parts, cleaning turbocharger oil filter and inlet and outlet oil pipeline, to ensure smooth lubricating oil.
Three, diesel generator trouble repair
1. Generator cannot start:
(1). Check whether the battery voltage reaches the rated voltage DC48V (depending on different voltage levels).
Because when the generator is in automatic state, its electronic control module ECM monitors the state of the whole unit and the contact between the EMCP control panel is maintained by battery power supply. When the external battery charger fails, the battery cannot be replenished and the voltage drops. At this time, the battery must be charged. The charging time depends on the discharge of the battery and the rated current of the charger. In case of emergency, replace the battery. When the storage battery is used for a long time and its capacity seriously decreases, it cannot be started even when the rated voltage is reached. The battery must be replaced.
(2). Check whether the battery terminal is in bad contact with the connecting cable.
Battery electrolyte in peacetime maintenance such as too much, easy to overflow battery surface corrosion terminal increases the contact resistance to make the cable connection bad. In this case, sand paper can be used to grind the corrosion layer of the terminal and cable joint, and then tighten the screw to fully contact.
(3). The positive and negative cables of the starter motor will produce weak wiring, because the vibration during the operation of the generator will loosen the wiring and cause poor contact.
The probability of failure of the starter motor is small, but it cannot be ruled out. To judge the action of the starter motor, you can touch the shell of the starter motor at the moment of starting the engine. If the starter motor does not move and the shell is cold, it indicates that the motor does not move. Or the starting motor is seriously hot, there is a smell of burning, then the motor coil has been burned. It takes a long time to repair the motor. It is recommended to replace it directly.
(4) there is air in the fuel system.
This is a common fault encountered, usually in the replacement of fuel filter element improper treatment (such as replacement of fuel filter element after the exhaust work) caused by air into. After the air enters the pipeline with the fuel, the fuel content in the pipeline is reduced, the pressure is reduced, and the fuel injector is not enough to open the nozzle to reach 10297Kpa high pressure oil spray atomization, leading to the engine can not start. At this time, exhaust treatment is needed to wait until the fuel pump inlet pressure reaches more than 345Kpa.
2. The cooling water temperature is too high
(1). It is usually caused by the unclean surface of the cooling water tank radiator.
The dusty environment is easy to block the surface of the radiator or the sundries are sucked by the cooling fan to the water tank to block the ventilation and make the heat dissipation poor. It can be solved after cleaning the surface of water tank radiator or removing sundries. (Keep the environment in the equipment room clean.)
(2) The coolant in the cooling water tank is insufficient.
It is necessary to check the cause of cooling water loss, check whether there is leakage of cooling water tank and cooling water pipes of the fuselage, and repair it immediately if there is leakage. Then replenish coolant to normal level.
(3) After the generator is used for a long time, the cooling fan belt will gradually aging and become elastic or a belt fracture will cause the cooling fan to lose its normal blowing ability.
At this time, it is necessary to replace the cooling fan belt, the whole group of belts should be replaced together rather than just one of them. There is a great difference between the elasticity of the old and new belts. When the generator is running, the cooling fan is subjected to large centrifugal force and air shear force. The elastic difference between a group of belts is not easy to drive the cooling fan, and the fan blade is easy to lose balance. The matching between the cooling fan and the steel guard and the cooling water tank is fine, and the change of balance may cause the collision of the fan, and the last three components will be damaged.
Another situation is that the belt pulley bearing of the cooling fan sags after wear, causing belt relaxation, affecting the blowing ability. As long as the usual maintenance of cooling fan pulley bearing lubrication can be avoided.
(4) The failure of cooling water pump leads to the non-circulation of cooling water and the rise of water temperature.
This is due to the pump after a long time of internal gear wear leakage caused. This fault is also rare in the standby oil generator. Contact the manufacturer to repair or replace the pump.
(5) The temperature regulator fails to open, so that the circulation path of cooling water cannot be changed when the water temperature of cooling water changes, and the flow of cooling water into the cooling water tank can be controlled to achieve the purpose of regulating the cooling intensity. The thermostat needs to be replaced.
(6). The use of unqualified coolant makes the cooling water pipe accumulate scale, rust and other objects that hinder the circulation of cooling water and cause the rise of water temperature.
The coolant should be a mixture of water and antifreeze or water and antirust, with a PH value between 6 and 8, usually pure water. For the cooling system that has been seriously deposited or blocked, it is better to mix it with clean water in a ratio of 0.5 liters of detergent per 7 liters of cooling system volume. After circulating cooling water for 90 minutes, clean the water again, so as to avoid corrosion of the residual detergent in the pipeline.
The generator exhausts black smoke
(1) the quality of fuel oil is poor and contains many impurities.
Impurities blocked the nozzle so that the cylinder can not completely burn and cause black smoke; In addition, when the engine nozzle injection pressure, some fine and hard impurities will scratch the nozzle wall. After the nozzle was scratched, the precision of fuel injection was changed, and the nozzle was damaged, causing great damage to the engine. If the nozzle is damaged, even if the use of qualified fuel will also emit black smoke. So the quality of fuel must be well closed, the selection of qualified fuel is conducive to the service life of the engine.
(2) environmental dust debris, air filter seriously blocked.
The air intake filter is blocked, resulting in insufficient combustion air in the cylinder and incomplete combustion. To clean or replace the air filter element, and maintain a clean environment.
(3) the timing of fuel injection of the engine is not correct.
The work of each cylinder of the engine depends on the calibration of its fuel injection time, that is, the piston needs to be corresponding to the fuel injection in the process of doing work, and the time difference between the two will cause incomplete combustion and black smoke. In this case, it is necessary to adjust the engine injection timing and valve clearance.
The generator exhausts blue smoke
(1). It is generally caused by too much oil in the filter (too much oil is added in the maintenance time), which can be solved by reducing the oil to the specified level.
(2). The piston ring is stuck or worn too much, and the lack of elasticity makes the oil leak into the combustion chamber. This requires cleaning the piston ring or replacing the piston ring on the leaking part.
Generator exhaust gives off white smoke
(1). Caused by moisture in the fuel system. The bottom of the oil storage tank can be discharged to check whether there is water.
(2). When the air flow changes after the wear of the cylinder valve, white smoke with smoke rings will be discharged. The worn parts must be replaced.
(3). Poor atomization of fuel injection nozzle, and diesel droplets are not burned in the combustion chamber. The nozzle must be checked and adjusted to the specified injection pressure
Four, diesel generator maintenance
In order to obtain the large operation safety and service life of the unit, it is necessary to carry out regular maintenance of the unit. If the relevant regulations of the unit maintenance can be complied with, the performance of the unit can be guaranteed. Correctly identifying the marks (graphics, text, warning, etc.) on the body of the diesel generator set is of great help to the correctness of maintenance and the safety of operation and use. When the unit is maintained, it must be carried out under shutdown, and it is necessary to remove the negative battery cable of the unit to ensure that the unit will not be started by mistake.
1. Lubrication system
(1) Lubricating oil and lubricating oil filters need to be replaced every 50-250 hours or at least every 6 months; According to the quality of lubricating oil and the sulfur content of fuel oil and the different lubricating oil consumed by the engine, the cycle of unit replacement lubricating oil will be different.
Main functions of lubricating oil:
A. The function of lubricating oil is to lubricate various parts in the engine and form an oil film between the two surfaces to reduce friction resistance and make the operation more smooth.
B. Sealing effect. The lubricating oil must be able to form an effective seal between the piston ring and the cylinder to prevent the leakage of steam and the intrusion of external pollutants.
C. Cooling effect. In the process of operation, the friction between parts produces a lot of heat or high temperature, the role of lubricating oil is to cool and reduce the temperature of the engine.
D. Cleanliness. Remove harmful impurities and insoluble substances that are not burning from the parts to keep these contaminants away from the lubricating surface and avoid the formation of sludge.
E. Anti-corrosion function. If the lubricating oil can provide complete separation of the oil film of the contact parts, it will reduce the chance of contact and wear of the parts, and avoid the corrosion of the metal surface.
2. Cooling system
(1) The maintenance cycle of the fan belt is once every 100 hours of operation.
Check the tension of each belt and replace it in time if it is damaged or invalid. Lubricate the fan pulley and belt tensioner bearings.
(2) The repair and maintenance cycle of the radiator is once every 200 hours of operation.
A.. External cleaning: Spray with hot water (adding detergent) from the front of the radiator facing the fan (if sprayed from the opposite direction will only push dirt into the center). Cover the diesel generator with tape when using this method. If the above method does not remove stubborn sediment, the radiator should be removed and immersed in hot lye water for about 20 minutes, and then cleaned with hot water.
B. Internal descaling: drain the water from the radiator, and then unseal the radiator where it is connected to the pipe. Pour 4% acid solution at 45 ° C into the radiator, let it dry for 15 minutes and check the radiator. If there is still water stain, clean again with 8% acid solution. After descaling, neutralize twice with 3% alkali solution, and then rinse with water for more than three times. When all work is done, check the radiator for leaks and repair if any. If there is no water leakage to reinstall, radiator installed back should be filled with clear water and add rust inhibitor.
(3) The coolant needs to be replaced every 300 hours. The PH value measured before and after the replacement should be 6-8, and the measurement record should be made. If necessary, the coolant should be injected
3. Air inlet system
Air filters need to be replaced every 400 hours of operation. Loosen the iron ring, remove the dust collector and filter element, clean the filter element carefully from top to bottom. When the filter element is not too dirty, it can be blown clean directly with compressed air, but attention should be paid to the air pressure can not be too large, the nozzle should not be too close to the filter element. If the filter element is too dirty, you should buy the best cleaning solution to clean it, and then dry it with an electric air duct (pay attention to not overheating). After cleaning, it should be checked. The method of inspection is to use the bulb to shine from inside out and observe the filter element externally. If there is light spot, it indicates that the filter element has been perforated. If no light spot is found, it indicates that the filter element is perforated at the end, and the air filter should be carefully installed.
4. Fuel system
The diesel filter should be replaced every 300 hours, and the oil tank and pipelines should be thoroughly cleaned first. Then put in a new filter, fill it up with fresh, clean diesel, and put it back in place.
5. Exhaust system
(1) Check exhaust blockage and leakage
(2) Discharge silencer carbon accumulation water.
6. Charging system
Check that the electrolyte of the battery is at the normal level. Before filling the battery, clean the filling port to prevent dirt from falling into the battery. Need to add liquid, add pure water to the right amount, do not add too full. Otherwise, when the battery is discharging or charging, the electrolyte inside the battery will overflow from the charging port, causing corrosion to the surrounding objects. Check regularly whether the voltage is correct and whether the joint is loose. Each startup time of the generator is less than or equal to 10 seconds, and the next startup interval should be more than 2 seconds. This is to protect the starter motor and storage battery. When starting the diesel engine, the starting current of the starter is 300 ~ 400A. If the starting time is too long or continuous starting, the electric starter coil will heat up so that the battery will be burned out or damaged.
7. Generator part
Check valve clearance, check fuel injector, clean carbon brush, check whether the transmission device is flexible, start the motor gear wear, check whether the turbocharger leakage, etc.
8. Automatic control device
Check whether the analog power supply, power outage and automatic device of oil starter are normal
9. Clean the unit
When cleaning, disconnect all the power supply, in addition to the external dust, dirt, oil stains, ventilation network should also be clean, because these things into the coil, will make the coil overheating or damage the insulation. Dust and dirt with a vacuum cleaner, do not blow or high-pressure water to clean. The insulation resistance of the generator will be reduced due to the return of moisture
The control panel
Generator control panel maintenance cycle for every half a year. Unit control panel daily maintenance should ensure its surface clean, make the instrument display clear and intuitive, operation button (key) flexible and reliable. In the operation of the unit, vibration will cause control panel instrument zero deviation, fastener loosening, so it is necessary to regularly control panel calibration, fastening connectors, connecting line work.
