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Diesel generator engine maintenance and maintenance skills

Diesel engine is the core component of the machine, so engine maintenance and maintenance is essential. Diesel maintenance and maintenance technology are discussed here.

Maintenance skills

1. Diesel fuel "speed" phenomenon and emergency measures

"Speed" or overspeed driving is a unique phenomenon in diesel engines. "Speed out of control", when the engine speed and speed are getting faster and faster, even exceeding the maximum speed allowed, is accompanied by a huge noise, resulting in serious mechanical damage and scrapping. There are two main causes of "speed" : first, the governor himself did not adjust to the normal feature of the loss; On the other hand, change the diesel engine power, is the characteristics of the fuel injection pump characteristic governor also without failure, and in the operation of diesel engine additional diesel or oil processed into the combustion chamber. The phenomenon of "speed" should be taken urgent measures of the high - speed diesel engine to a certain extent. Emergency measures to stop speeding are:

(1) the accelerator pedal quickly retracted to berth.
(2) deceleration device, and quickly pull the handle to reduce the pressure of the station oil position (or the pressure relief position).
(3) timely contact to enter the climax, ride on the brake pedal, slowly cancel the clutch, and turn off the diesel engine.
(4) the high-pressure oil pipe is rapidly disconnected and the fuel supply is stopped.
(5) the quick tension of the air filter in the clothes bag killed the diesel engine.

These five steps are called "slow, vacuum braking, dead."

2. Inspection methods for each cylinder of diesel engine

Check the work of the engine by the following methods when each cylinder diesel is idling:

(1) listening method: close to the body of the syringe with a stethoscope or stick, and listen to the sound of explosion of each cylinder. The sound of normal metal percussion is similar to that of "dangle". If there is only "good", it is not only a sound row, but then little or no oil at all tank fire time, such as the sound of a big drum indicates that the injection volume of the tank is too large or too early.
(2) legal concept of color: when the engine is working normally, the discharge from light grey is large and a little deep. If exhaust black gas, it indicates that combustible gas does not fully burn. The oil of discharge blue flame enters cylinder to burn. White smoke, then in diesel water, burning combustible gas, is also white smoke. The unusual color of continuous exhaust emissions indicates that the individual cylinder is not working properly.
(3) temperature: in the initial stage of diesel engine starts (work after a period of time the exhaust temperature is very high, with the hand touch will burn) by hand touch each cylinder exhaust temperature, can identify each cylinder working condition. If the temperature of each cylinder's exhaust pipe is higher than that of other cylinders, the oil supply of this cylinder is higher. If the temperature is low, the oil supply of the cylinder is small, or does not spray, or does not fully burn or do not burn after the injection.
(4) pulse method: hold the high-pressure oil pipe tightly by hand, and feel the pulse condition of oil spraying. Abnormal sound and high temperature are caused by the decrease of oil pressure, bad atomization, or failure to catch fire and complete combustion. High pulse, strong explosion sound, high temperature of the cylinder for large oil supply. The weak sound and low temperature of the explosion are caused by the nozzle or needle valve sticking.
(5) oil breaking method: in order to accurately determine which cylinder is in fault, the high-pressure oil pipe can be cut off from the injector oil road one by one to stop the work, so as to observe the changes of the working condition of diesel engine. When a cylinder oil road is cut off, if the diesel engine speed and sound do not change or change little, it indicates that the cylinder works normally. If the cylinder is knocked intermittently and the black smoke is discharged, when the oil road of a cylinder is cut off, the fault phenomenon disappears, indicating that the fault is in the cylinder.

3. Five methods of fuel saving for diesel engine

(1) use oil-saving smoke reducer. The oil-saving smoke reducer is fixed vertically in the front-end oil circuit of the fuel injection pump and connected to the dc power supply. When used in diesel engines, smoke reduction is significant. It can reduce environmental pollution and save about 5% oil.
(2) install the inertial supercharger. The installation of inertial supercharger on diesel engine can increase power by 15% and reduce fuel consumption by 3% ~ 5%.
(3) cover the filter element with toilet paper. Wrapping 2-3 layers of absorbent toilet paper on the oil filter element of diesel engine can improve oil cleanliness and reduce fuel consumption.
(4) add foam plastic air filter element. In the two-layer filter screen of air filter, an 8-20mm thick foam plastic with good air permeability is added, which can improve the filtration effect, keep the oil burning normally and reduce the oil consumption.
(5) return pipeline diversion. The return oil of diesel engine is connected to the high pressure oil pipe, so that the return oil can enter the low pressure oil pipeline, which can ensure the normal combustion.

Maintenance skills
1. "three leaks" To repair the diesel engine and prevent and solve the problem of "three leaks", the "five words" principle can be adopted, that is, strict, clean, wipe, grind and tighten.
Strict: the disassembly and installation of the parts must be strictly required, follow the operating rules, strictly prohibited to disturb and knock. If the bolt is screwed, it should be tightened in order and several times.
Jie: the parts must be clean before assembly. If the oil outlet valve and the seat contact ring are mixed with minimal debris, not only will the oil leak, but also directly affect the work of the diesel engine.
Wipe: apply asbestos oil to asbestos pads, paper pads, various bolts and oil spills. When applying asbestos oil, it should be thin and even. It should not be too thick.
Grinding: the binding surface of the grinding or milling parts, whose function is to restore the surface smoothness and precision, so that the tubing joints or gaskets can be kept sealed after grinding without oil leakage.
Tightness: the tightness of the sealing device should be appropriate, not too tight or too loose. For example, various contact surfaces and sealing nuts of diesel engines must be maintained in a suitable degree of compactness.

2. Cylinder pressure off. In order to ensure adequate cylinder pressure, fitting clearance of the piston and cylinder liner, piston ring, side clearance must conform to the requirements of end, valve and valve seat sealing, injector front end sealing better, cylinder pad, and thickness conform to the requirements.

3. Combustion chamber volume off. After the diesel engine is repaired, the combustion chamber volume changes, and the original compression ratio changes, which directly affects the normal operation of the diesel engine. The factors of changing chamber volume include: the piston position is reversed, the cylinder liner thickness is improper, the crankshaft connecting rod is worn or bent mechanically, the vortex chamber inserts are out of position, the valve is too large to sink. Attention should be paid to these situations during repair.

Time off. Timing including fuel supply timing and valve timing, if the oil supply is not timing, S195 type, X195 diesel engine can use between the fuel injection pump and the gear chamber cover gasket adjustment, each increase or decrease in 0.1 mm thick gasket, equivalent to the flywheel arc length 6.3 mm. If the distribution is insufficient, should check and correct the error of the timing gear installed on, and then adjust the valve clearance, valve clearance changes every 0.1 mm, 3 ° crank Angle changes, the equivalent of the flywheel arc length 11.1 mm, adjustment should be paid attention to when the piston compression to the check point on the inlet and exhaust valve clearance (cold) not less than 0.2 mm, in case of parts heat expansion valve closed lax, or valve head impact piston.

5. "three filters" off. The bad state of air filter technology will cause dust to enter the cylinder, accelerating the early wear of piston ring, cylinder, valve and valve seat, causing start-up difficulty and power reduction. Diesel oil, oil filter technology condition is bad, can make the impurities into the relevant parts, and between the three big precision coupling early wear and tear, accelerate the crankshaft and bearing wear, severe cases can cause diesel engine early scrapped.

6. Diesel atomization off. Plunger vice, delivery valve and injector needle valve deputy technical condition is bad, will cause the fuel injection spray, diesel engine starting difficulty, incomplete combustion, carbon deposit increased, so that diesel engine power decrease, and fuel consumption increase, therefore, the fuel oil system, especially the precision matching parts to check carefully.

7. Through hole and through hole.
(1) through-hole shutoff: now take S195 diesel engine as an example, 5 through-hole of bearing and bushing should be aligned when installing.
A. main bearing. Each pair of main bearing oil hole is drilled on the groove, respectively, and the cylinder block, the oil hole on the main journal, when installation, as long as the main bearing flange gap alignment positioning pin, and can prevent the main bearing rotation, guarantee the oil hole alignment, make the lubricating oil road unimpeded, avoid damage.
B. Rocker arm bushing. When the liner is pressed into the rocker arm, if the hole is not aligned, the rocker arm shaft and the liner will burn out due to lack of lubrication and dry friction, resulting in a larger valve clearance and a serious knock.
C. connecting rod bushing. Connecting rod small head set oil hole is drilled, and the connecting rod bushing oil hole, the connecting rod little head inside set of copper set, if the two oil hole is not aligned, copper sleeve and the piston pin "dangdang" tapping, or even killed.
D. Starting axle bush. Starting shaft bushing, the installation of two bushing oil hole respectively with the body and gear to cover those corresponding oil grooves are interlinked, or starting shaft and bushing will speed up the wear and tear, caused by oil supply Angle and the distribution of phase change, resulting in a decline in the diesel engine power.
(2) hole shutoff: there are mainly the following four holes.
A. The oil tank cover has air vent. The hole plugging, fuel tanks and atmosphere are interlinked, no longer tank top for oil level down there will be a negative pressure, oil supply disruption caused fuel heated evaporation, make the tank pressure increases, will cause oil tank switch place, therefore, this hole is not blocked.
B. Crankcase air vent. In pores blocked, inside the crankcase emission is piling up, inside the crankcase pressure increases, can make the engine oil leakage, high temperature exhaust gas mixed with oil, and will also speed up the oil metamorphism, accelerate the parts wear, therefore, must open the hole in the maintenance.
C. drain hole of oil pump. The oil drain hole on the oil pump is blocked, which will lead to a small amount of diesel leakage between the push rod and the conduit into the oil pump, dilute the lubricating oil in the shell, and accelerate the wear of parts. Therefore, this hole cannot be blocked.
D. Water pump drain hole. If the hole is blocked, the leaking water will not drain out of the pump body and enter the bearing pedestal, which will accelerate the damage of the bearing. Therefore, the hole must be dredged during overhaul.

8. Grinding and closing.

(1) cold grinding. Fuel injector, with external force driving operation of diesel engine, check the oil pressure and temperature of different parts at the same time, pay attention to listen to the voice parts, cold after running-in, while at high temperature out oil, wash oil filter and oil.
(2) thermal grinding. Without heat load running-in, pay attention to each part of the diesel engine working conditions and noise, the thermal load and the stipulated time, always pay attention to each part sound and oil into gas and smoke exhaust, fuel injector oil return, etc., found that the problem should be ruled out in time.