Diesel engine is an internal combustion engine that uses diesel fuel as fuel, and has the remarkable advantage of high thermal efficiency. Especially in agricultural applications, diesel engines are one of the indispensable agricultural machinery in agriculture, but they are the main force for agricultural development. So in this issue, I will explain the relevant knowledge of diesel engines in detail for you.
1 Introduction to Diesel Engines
A diesel engine is an engine that burns diesel for energy release. It was invented by German inventor Rudolf Diesel in 1892. In honor of the inventor, diesel is represented by his surname Diesel, and diesel engines are also called Diesel engines ( Diesel engine).
2 Advantages and disadvantages of diesel engines
Advantages: large torque and good economic performance. Each working cycle of a diesel engine also experiences four strokes of intake, compression, power, and exhaust. However, because the fuel used in diesel engines is diesel, its viscosity is higher than that of gasoline, it is not easy to evaporate, and its auto-ignition temperature is lower than that of gasoline, so the formation and ignition method of combustible mixture are different from those of gasoline engines. The main difference is that the mixture in a diesel engine cylinder is compression ignited, not ignited. When the diesel engine is working, it is air that enters the cylinder. When the air in the cylinder is compressed to the end point, the temperature can reach 500-700 ℃, and the pressure can reach 40-50 atmospheres. When the piston is close to the top dead center, the high-pressure pump on the engine injects diesel oil into the cylinder with high pressure, and the diesel oil forms fine oil particles, which are mixed with high-pressure and high-temperature air, and the diesel mixture burns by itself, expands violently, and generates explosive force, which pushes the piston down to do work. , the temperature at this time can reach 1900-2000 ℃, the pressure can reach 60-100 atmospheres, and the torque generated is very large, so diesel engines are widely used in large diesel vehicles.
Disadvantages: Due to the high working pressure, the relevant parts are required to have high structural strength and rigidity, so the diesel engine is relatively heavy and bulky; the fuel injection pump and nozzle of the diesel engine require high manufacturing precision, so the cost is relatively high. In addition, the diesel engine works rough, and the vibration and noise are large; the diesel oil is not easy to evaporate, and it is difficult to start the car when it is cold in winter.
3 Classification of diesel engines
1. According to the working cycle, it can be divided into four-stroke and two-stroke diesel engines.
2. According to the cooling method, it can be divided into water-cooled and air-cooled diesel engines.
3. According to the intake method, it can be divided into supercharged and non-supercharged (naturally aspirated) diesel engines.
4. According to the combustion chamber, it can be divided into direct injection type, swirl chamber type and pre-combustion chamber diesel engine
5. According to the number of cylinders, it can be divided into single-cylinder diesel engine and multi-cylinder diesel engine.
6. According to the purpose, it can be divided into marine diesel engine, locomotive diesel engine, automobile diesel engine Diesel engines, diesel engines for generator sets, agricultural diesel engines, diesel engines for construction machinery, etc. Vehicle diesel engines are mostly arranged in in-line and V-shape.
7. According to the layout, it can be divided into in-line diesel engine V-shaped diesel engine, horizontally opposed diesel engine, star diesel engine, king-shaped diesel engine, etc.
8. Diesel engines can be classified according to the speed of piston evaluation, low-speed diesel engine, cm<6M/S, medium-speed diesel engine, cm=6-9m/s, high-speed diesel engine, cm=9-13m/s
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4 Diesel Engine Purchase
1. The product manufacturer should obtain the production license and the agricultural machinery product promotion license issued by the Ministry of Agriculture. Each product has the logo and certificate number of the above two certificates.
2. The appearance is beautiful, neat, and the color is uniform and bright; the surface has no scratches, deformations, defects, and the baking paint has no defects such as leaking paint, flowing paint, peeling, scratches, etc.; Trachoma or cracks; the connecting bolts are fastened, and the layout of each component is reasonable. Protective devices should be provided for exposed rotating parts such as flywheels, starting claws, etc., which are at risk of entanglement, and exhaust pipes and water tanks that are at risk of high temperature.
3. The on-board tools and spare parts are complete, the “Three Guarantees” maintenance card and its contents meet the requirements, the use and maintenance instructions are detailed, and the product certificate or instruction manual has the product standards implemented by the product Code ID.
5 Diesel Engine Instructions
(1) Pay attention to the oil pressure. When the diesel engine is working, the oil pump is used to press the weeping oil to the friction surfaces of the parts and form an oil film, so that the parts that are rubbing against each other do not come into direct contact, thereby reducing the friction loss. During use, you should pay attention to the oil pressure at any time. When the oil pressure is too low, you should immediately stop for inspection and maintenance. If the oil pressure is too high, it will also damage the oil film and increase the wear. The cause should also be identified and eliminated in time.
(2) Pay attention to changes in temperature. The temperature of the diesel engine is mainly reflected in the temperature of the cooling water and the temperature of the lubricating oil. When the forced circulation diesel engine is working, the water temperature should be kept between 70-90 degrees Celsius, and the oil temperature should be kept between 70-80 degrees Celsius. If it is too high, it will damage the cylinder head gasket, piston and piston ring, reduce the viscosity of the oil, and reduce the lubricating performance; if it is too low, it will increase fuel consumption and smoke exhaust. Therefore, the temperature of the cooling water should be paid attention to at any time during the work, and the abnormality should be eliminated in time.
6 Diesel Engine Maintenance
Diesel engine maintenance is divided into shift maintenance and regular maintenance. Shift maintenance is carried out after each shift, and regular maintenance is carried out after a certain period of work.
(1) Shift maintenance
①Clean the exterior of the machine, check and eliminate oil leakage, water leakage and air leakage from all parts.
②Check whether the connection between the machine and each accessory device and instrument is firm and reliable, and tighten it in time if it is found to be loose.
③ Check whether the diesel oil, engine oil and cooling water are sufficient, if they are insufficient, add enough oil in time, and regularly add lubricating oil to the artificial refueling place, and check whether the oil circuit is smooth. In dusty areas, every shift The air filter should be cleaned after work.
(2) First-level maintenance
First-level maintenance should be performed after the diesel engine has been running for 100 hours. In addition to the completion of shift maintenance, the following maintenance contents should also be completed.
①Replace the oil, clean the oil pan…
7 Diesel engine failure
Water block damage
The diesel engine suddenly spews a large amount from the respirator during operation oil. The first judgment is that the water plug on the cylinder head is damaged. After the water plug is damaged, the cooling water leaks into the oil pan, and the oil level rises. Because the oil is lighter than water and floats on it, the crankshaft rotates and splashes the oil out of the respirator. If the water plug is in good condition, then check whether the cylinder head is cracked, the body or the water blocking ring is damaged, and the cylinder head gasket is washed out.
Burning of tiles
Diesel engine is running, but the throttle is not moved but the speed gradually decreases, and the engine turns off automatically after a black smoke is emitted, which can be concluded that it is burning tiles. When checking, turn the flywheel first. If it can still turn, but it is very heavy, it means that the shaft and the shoe are not locked. If the rotation feels light and then sinks, it proves that the connecting rod bush is burned; if the rotation feels heavy at any position, it is the crank bush that is burned.
