Common Faults and Countermeasures of Small Gasoline Generator Set

1 Overview

A generator is a mechanical device that converts other forms of energy into electrical energy. It is driven by a water turbine, steam turbine, diesel engine or other power machinery. It converts the energy generated by water flow, air flow, fuel combustion or nuclear fission into mechanical energy and transmits it to the generator. The generator is converted into electrical energy. The gasoline engine drives the generator to convert the energy of gasoline into electrical energy. In the cylinder of a gasoline engine, the mixed gas burns violently and expands rapidly in volume, pushing the piston down to perform work. Each cylinder performs work in a certain order, and the thrust acting on the piston becomes the force that pushes the crankshaft to rotate through the connecting rod, thereby driving the crankshaft to rotate. By installing the brushless synchronous alternator coaxially with the crankshaft of the gasoline engine, the rotation of the gasoline engine can be used to drive the rotor of the generator. Using the principle of "electromagnetic induction", the generator will output induced electromotive force, and current can be generated through the closed load circuit. In the construction process of the site, it is often necessary to temporarily exhaust, drain, power supply, lighting, etc. These equipment are often powered by small generator sets. At present, the small power generation equipment used in the construction site is generally a gasoline generator set. Small gasoline generators generally use gasoline engines as the driving force to drive the generator T. The generator has two kinds of permanent magnet generator and excitation generator. The permanent magnet generator has magnets on the rotor, which establish a magnetic field by the magnetism of the magnets. When the engine drags the rotor to rotate, there is a rotating main magnetic field, and then the magnetic field is cut by the relative movement between the stator coil and the rotating rotor. Generate induced current.

The principle of the exciter generator is basically the same as that of the permanent magnet machine, but the rotor of the exciter has no magnet and is also a coil, so a carbon brush is used to provide a DC current to the rotor coil, so that the rotor coil generates magnetism, and then generates an induced current. The structure of the permanent magnet generator is simpler than that of the excitation generator, and the failure rate is low, but the maintenance of the excitation generator is more convenient, the stator rotor can be easily disassembled, and the permanent magnet generator has a phenomenon such as broken magnet, and the maintenance is quite difficult. easy. Moreover, small units use the engine to directly drive the generator. In order to achieve the output frequency of 50Hz, the engine must be maintained at 3000 rpm as soon as the engine is started. For the engine, it is a high-load operation, so it is usually used after use. The maintenance requirements for the engine are relatively high. Due to the harsh environment of T, it is often eroded by wind, rain and gray sand, so the failure rate of the unit is relatively high.

2 Common Faults and Countermeasures of Small Gasoline Generator Set

Insufficient 2.1 oil supply

Insufficient fuel supply is one of the most common faults of gasoline engines. This kind of fault often occurs in Dingdishi T, and its performance varies due to the degree of fuel shortage and the location of the fault. One is that the main hole is blocked and the oil supply is insufficient. After the machine is started, the rotating speed changes from high to low, the governor swings back and forth regularly, and the sound of the machine fluctuates regularly, emitting a rhythmic "blare, blare" sound. If the choke valve is closed at this time, the phenomenon disappears, but the rotating speed cannot reach the rated value, the machine power is insufficient, and the power cannot be supplied. Second, the oil circuit before the main weighing hole is blocked, resulting in insufficient oil supply. In addition to the above phenomena, the regular ups and downs will disappear briefly when the choke is closed,

It will appear again soon and the governor will swing more and more until it stops, sometimes accompanied by shooting. After stopping and waiting for a while, the machine can start again, and then the fault repeats. This kind of failure is mostly due to the blockage of the oil circuit by particulate impurities in the gasoline, or the blockage of the valve and quantity L due to the glue of the gasoline, which can be removed after discovery. It should be noted that the above phenomenon will vary depending on the rated power of the machine. The higher the power of the engine, the larger the fuel consumption, and the oil circuit may not appear to fluctuate and stop suddenly after the oil circuit is blocked.

2.2 ignition too weak

When the spark plug is weak, the engine performance is that the T is weak, the speed is unstable, the vibration is intensified, there is a backlash in the cylinder, and it is accompanied by backfire or firing. The above phenomenon is aggravated with the aggravation of the degree of failure. There are three common reasons for weak ignition: first, excessive carbon deposits. When the machine T working environment is too dirty, the T working time is too long, frequent startup or poor cylinder combustion, and poor oil quality, it is easy to form carbon deposits between the spark plug electrodes, which will cause weak ignition. When carbon deposits are found, just remove the spark plug. Clean; the second is that the electrode gap is too small. This kind of fault can be determined by visual inspection or measurement with a thickness gauge. It is generally caused by improper use or repair, as long as the gap is adjusted according to the specified value of the unit; the third is the spark plug insulating porcelain core or high-voltage line leakage. When the insulating porcelain core and high-voltage line are damaged, or when the use time is too long, it is easy to produce leakage. Whether the spark plug and high-voltage line leak can be checked by the method of fire test, and it can be replaced when the leakage is determined. In addition to the above three common reasons, the failure of the internal components of the magnetron can also lead to weak or even no fire, which can also be determined by the method of test fire. When the magnetron is faulty, the magnetron can only be replaced as a whole.

Poor 2.3 air intake

The failure phenomenon of poor air intake of the engine is more obvious. After the machine is started, the sound is relatively dull, the exhaust emits black smoke, the speed does not reach the rated value, and the unit cannot supply power. This kind of fault is mostly caused by the blockage of the intake part. In practice, the most clogged part is the air filter. When the unit is used for a long time, or often in a dirty environment, it is easy to cause the air filter to accumulate dust and block, so that the engine air intake is not smooth, and a large amount of dust enters the cylinder, which will speed up the cylinder carbon deposition Speed, poor ignition of the engine, insufficient power, increased fuel consumption of the engine, and also accelerated the wear of the cylinder. Therefore, the air filter should be checked regularly. If the filter dust is too much, it should be removed by appropriate methods according to the material of the filter element. For paper filter elements, compressed air can be considered to blow out from the inside of the filter to blow out the dust. However, the pressure of the compressed air should not be too high to prevent the filter paper from being damaged, and water or oil should not be used to prevent the oil and water from dipping the filter element; for the sponge filter element, first clean the dust with gasoline, and then soak the sponge with clean engine oil. Squeeze the excess oil by hand and use it.

2.4 valve leakage

Leakage of the valve will cause the compression force of the cylinder to decrease and the gasoline combustion will not be sufficient. When the valve leakage is serious, the machine is not easy to start, the engine speed is unstable after starting, and the T-cloth will hear the hiss of "whoosh, whoosh", and at the same time, the exhaust emits black smoke or the carburetor has backfire and blow-by phenomenon. There are several common reasons for valve leakage: one is improper adjustment of valve clearance, the other is severe valve ablation, and the third is carbon deposits on the valve head or valve stem. If the valve is found to be leaking, first visually check whether the valve clearance meets the requirements. If it does not meet the requirements, adjust it; if the fault phenomenon still exists, check whether the valve head or valve stem has carbon deposits and whether the valve is ablated. If the valve has carbon deposits, it should be cleaned; if the valve

For ablation, remove the valve spring, intake and exhaust valves, etc., first clean these parts with gasoline, then use No. 120 coarse sandpaper for rough grinding, then use No. 280 fine sandpaper for fine grinding, or use grinding sand for grinding, Until the valve and the valve seat are completely attached; if the valve ablation is serious, reaming should be performed first.

2.5 cylinder air leakage

In addition to valve air leakage, other common reasons for cylinder air leakage are: one is air leakage in the cylinder gasket, the other is excessive wear of the cylinder liner and piston ring, and the piston ring has insufficient elasticity. The third is that the piston ring dies in the piston ring groove due to carbon deposits. The failure phenomena caused by different reasons are also different. If the cylinder head gasket leaks air, there is no compression feeling when the machine rotates, it is difficult to start, and there is a "hissing" air leakage sound at the cylinder head gasket. After starting, the air leakage will increase and blue smoke and black oil droplets will spray out from the fault point. The machine speed is unstable, the power is insufficient, and there is a shooting phenomenon, which is especially serious before shutdown, when turning the machine, there is also no sense of compression. You will hear the sound of air leakage from the cylinder. After starting, sometimes you hear the sound of metal impact in the cylinder, blue smoke from the exhaust pipe, and sometimes there will be a shooting phenomenon. Check the oil after a period of time, you will find that the oil becomes thinner and the oil level rises. The above three causes of failure are relatively easy to identify. If the cylinder head gasket is leaking, tighten the cylinder head bolts again according to the specified torque and sequence, and check whether the cylinder head gasket is damaged, otherwise replace it; if the cylinder liner and piston ring are excessively worn and the piston ring elasticity is insufficient, replace it according to the repair procedure Or increase the piston ring, or replace the standard cylinder liner and piston ring.

Concluding remarks

In summary, due to the characteristics of the gasoline engine itself, the failure phenomenon is more obvious after the failure. When the gasoline engine has different failures, it will cause different changes in the state of the machine T, and its sound and exhaust color will have different performances. We can perform fault diagnosis by listening to the machine and watching the color to ensure the small gasoline generator set Safe and stable operation.