In my opinion, compared with gasoline engines, diesel engines crush gasoline engines in all aspects except noise and vibration.
In the past, the working environment of those customers' diesel engines was so bad that they kept running day and night, and they lost tens of thousands of dollars if they stopped maintenance for one day. Usually an accessory needs to be airlifted, so if it is installed quickly, they must continue to work.
And we often meet models in the 1980s and 1990s who are still buying accessories. If a machine is properly maintained, it will be normal to use it for more than ten or twenty years. You can imagine how many miles it will convert if it is fully loaded, driving at the speed of 120 and driving day and night for more than ten years. Finally, many machines were replaced because of factors such as fuel consumption and emissions.
The diesel engine looks silly and simple in structure, but it is not easy to build it well, especially the high-pressure fuel injection system, which is the core technology and requires high technology. Therefore, China's heavy-duty diesel engine market has been monopolized by foreign brands for a long time, and it has only made a breakthrough in recent years.
As for why diesel engines are more durable than gasoline engines, we can simply explain them step by step from the following two aspects! 1, diesel engine ignition mode
Diesel oil is very volatile, unlike gasoline, which is easily mixed with air to increase its combustible surface, thus forming combustible gas. Therefore, even if the ignition point of diesel is lower than that of gasoline, it is still difficult to be ignited by spark plugs in engines.
However, it is precisely because the ignition point of diesel oil is lower than that of gasoline that we can use the method of rapidly compressing air in a closed space to generate heat, so that the temperature in the cylinder can quickly reach the combustible temperature of diesel oil, and then the atomized diesel oil can be ignited by compression ignition under the action of a more efficient fuel injection pump.
Compression ignition engine has high energy conversion efficiency. In the process of "compression ignition-doing work" of fuel, the energy loss is only about half of that of gasoline engine, so Mazda also began to adopt the compression ignition principle on gasoline engine to make it have better fuel economy and power.
2. Disadvantages of diesel engine compression ignition mode.
For this, we can first know about the ignition source of gasoline engine, which has only one: spark plug.
The spark plug can ignite the gasoline before the piston reaches the top of the cylinder in the compression stroke, so as to avoid the problem that the gasoline burns ahead of schedule due to the high internal temperature of the cylinder.
It can be said that one of the purposes of spark plug pre-ignition is to control the combustion attitude of gasoline in the cylinder, so that the energy released by gasoline combustion spreads in the form of points, thus preventing multiple ignition points from appearing in the cylinder due to gasoline pre-ignition.
However, the main problem of diesel compression ignition mode is that it will cause too many ignition points in the cylinder.
Compression ignition of diesel engine can't make the ignition attitude of fuel diffuse in a point way, and it will produce multiple combustion points in the cylinder. We can imagine each combustion point as a miniature energy explosion point. When they release energy, they will collide with each other and bounce back to the cylinder wall, which will bring the phenomenon of cylinder wall vibration.
Cylinder vibration will naturally affect the stability and quietness of the engine, which is one of the reasons why diesel engine jitter and noise are greater than gasoline engine. Therefore, if the engine wobbles when the gasoline vehicle is driving or accelerating, it may be that the ignition angle of your spark plug is advanced.
However, the diesel engine's solution to this problem is also very simple, that is, increasing the wall thickness of the engine cylinder and using its own wall thickness to buffer this vibration energy. Moreover, a diesel engine compresses diesel by generating heat from compressed air, so its engine compression ratio will be much higher than that of a gasoline engine, and the temperature of compressed air in the cylinder will rise rapidly, so the working temperature of a diesel engine is obviously higher than that of a gasoline engine.
Therefore, we often see aluminum alloy engine blocks on gasoline vehicles, but it is difficult to see them on diesel engines.
Diesel engines are basically made of cast iron, which is more durable than aluminum alloy. In addition, the compression ignition mode of diesel engine does not need redundant electronic ignition system, so its auxiliary circuit configuration is much less than that of gasoline engine, so the durability of diesel engine is theoretically higher than that of gasoline engine.
But why do diesel engines feel less durable than gasoline engines in actual use? A car hot review thinks that the reason is actually very simple: the fuel injection system is different!
As mentioned in this paper, diesel oil is not volatile. Therefore, in order to fully atomize the diesel in the cylinder, it is necessary to equip the diesel engine with an injection system with higher injection efficiency and stronger injection force. For example, a truck is equipped with a set of high-pressure fuel injection pump.
However, the fuel injection system with higher injection efficiency and injection force will bring a new problem, that is, its accuracy requirements will be higher, which not only tests the manufacturing technology level of manufacturers, but also puts forward higher requirements for the quality of diesel oil.
If the quality of our diesel oil is not good, or the technical level of the fuel injection system is not up to standard, it will easily lead to the blockage of the fuel injection system, and the blockage of the fuel injection system will affect the working efficiency of the engine, thus causing a series of problems such as inconsistent combustion efficiency of each cylinder, missed combustion and engine jitter. When these problems occur in diesel engines, sometimes they are not necessarily caused by the defects of the diesel engines themselves.
For example, if someone buys a new diesel car, leaves a 4S shop, enters a gas station that provides inferior fuel, and adds inferior diesel, the new car may break down in a few days, probably because of the fuel injection system failure caused by inferior fuel.
In addition, the injection system with higher requirements and higher accuracy will have more stringent requirements on the environment than gasoline engines. For example, if your diesel vehicle works in a dusty environment for a long time, it will easily bring blockage problems to your fuel injection system, thus affecting the working efficiency of the engine.
To sum up, from the structural principle, diesel engine has many advantages that gasoline engine does not have, especially its maintenance will be relatively simple. However, whether it is a gasoline engine or a diesel engine, in order to prolong the life of the engine, we must first pay attention to regular maintenance of the engine to keep it in good working condition.
This theory itself is wrong. The first working principle of diesel engine is that the cylinder pressure is much higher than that of gasoline engine. At the same time, there are many high-pressure devices, including the plunger in the diesel high-pressure pump. Since it is high pressure, it means worse working conditions and higher material requirements.
At the same time, taking cylinder as an example, higher pressure means greater impact on piston and piston ring, and greater impact on crankshaft and bearing bush. ...
Aside from the advantages and disadvantages of energy utilization rate, cost-effectiveness ratio and power output, the service life of diesel engine is far less than that of gasoline engine only from the working conditions and material requirements.
Furthermore, because diesel engines are mainly used to produce power, they have high frequency of use, poor working environment and poor maintenance conditions, which all lead to the use time of diesel engines being inferior to that of gasoline engines.
The subject doesn't understand at all. Obviously, the life of diesel engine is much longer than that of gasoline engine, but he asked why the life of gasoline engine is longer than that of diesel engine.
Different from the appearance impression, the manufacturing accuracy of a "stupid" and loud diesel engine is much higher than that of a gasoline engine. Many parts of diesel engine are even parts, that is, if you change one of them, it will not meet the requirements, so you need to change them in pairs.
Compared with gasoline engines, diesel engines have another advantage: simple structure, no ignition system with poor durability and reliability, and low maintenance cost. Because of its simple structure, it becomes more reliable.
The working speed of diesel engine is lower than that of gasoline engine, which also brings life advantage. The same mileage, the speed is half lower, the wear is half less, and the life is twice as long.
In fact, the life of a diesel engine is more than twice that of a gasoline engine.
In Europe, 400,000-500,000 km diesel cars can still fetch a good price, but gasoline cars can't.
Large commercial vehicles use diesel engines, and the overhaul mileage of large diesel vehicles in Europe can reach 4 million kilometers, which is unimaginable in gasoline vehicles.
Why do you say that? There are not many diesel engines for passenger cars in China, and their service life is not shorter than that of gasoline engines. As for commercial vehicles, the logistics company ran 800,000 kilometers in the first year, and the mine excavators worked in three shifts. Excluding the driver's meals and maintenance, it is guaranteed to be 5000 hours a year, and there is no need for overhaul for four years.
Therefore, your question itself is wrong.
In theory, the principle of long life of diesel engine is mainly low speed and high strength! However, due to excessive carbon deposition in the combustion chamber and improper copying, the steel drawing will be serious! You will have a short life! But as long as we can really solve the problem of carbon deposition, we can prolong life! However, as early as 20 13 in 2008, China invented the invention patents (announcements) of "energy-saving method of diesel engine photolysis water combustion ~" and "an engine steam recovery photolysis compound combustion for energy saving and emission reduction ~"! Although I have been an inventor of China folk black technology for more than ten years! But I've been working hard on the experiment! ~ technology has improved strongly again! It can really make the exhaust emission of diesel locomotive (national third diesel engine experimental prototype) reach zero emission (0.02~0.07)! The fuel saving rate has reached 50%! It has also realized that diesel engines can "drink water every day, bid farewell to black smoke, save energy (50%), reduce emissions (0.02~0.07) and save money"! Benefit the country and the people and benefit mankind! Can make the gasoline and diesel engines of the Chinese people live for one hundred years! Therefore, people in China are waiting for China to introduce a new policy of energy conservation and emission reduction! Let my "water-photolysis compound burning dream" become a "Chinese dream" and a "human dream" as soon as possible! Dreams come true! Lead the world! Win glory for our country! !
Theoretically, the life of diesel engine is longer than that of gasoline. But theory is a theory after all, which is different from all aspects in practice. Because there is no perfect condition in theory in practice, the life of diesel engine in practice is shorter than that of gasoline engine. In short, it is meaningless to define reality by theory, and everything should be based on reality!
One of the reasons why the service life of our domestic diesel engine is not as good as that of gasoline engine is that there is something wrong with our oil. In Europe, the diesel engine runs100000 kilometers, and the diesel filter does not need to be cleaned. In our place, the diesel filter may not even reach 40 thousand kilometers, so the difference of oil products may shorten the service life of our domestic diesel engine. Moreover, the theoretical long service life of diesel engines is based on top-level maintenance. Many of our friends use diesel engines violently, so they can't keep up with them in a destructive way.
Usage and use determine the length of life. Think about it. Which cars in China are diesel? In fact, the vast majority of diesel vehicles in our country are tool vehicles and commercial vehicles, and very few belong to off-road vehicles and some high-end SUVs (the proportion of diesel engines in passenger cars is too low)! As we all know, passenger car owners cherish their cars the most, so only these diesel car owners can provide enough maintenance for diesel engines, but the proportion is too low; As for the maintenance of other tools and commercial vehicles, such as the diesel version, it is simply impossible. Many friends who run big cars will choose cheap diesel (the owner will pay the fuel fee to the driver in advance)!
Therefore, the life of diesel engine will be discounted; As for buying a diesel off-road vehicle, which one is not violent? Dedicated to that harsh environment, I jumped over the gravel Gobi and climbed the mountain when I had nothing to do. What car can stand it? Needless to say, diesel engines, even gasoline engines, are equally unbearable; And for those commercial vehicles and tool vehicles, which one is not overloaded or overloaded? Therefore, diesel engines cannot endure such violence for a long time; Therefore, the vast majority of diesel engines in our lives are violently used, lack of maintenance, and die young!
Finally, our relevant emission regulations are not very friendly to diesel engines, and we can't tell whether the oil is poor or the emission inspection is too strict. In short, the emissions of many diesel engines with short service mileage are problematic, so the last batch of diesel engines that survived by luck were folded in the emissions, which is the reason why our diesel engines have short service life. There are too many differences between America and Europe in oil products, usage methods, maintenance and attitudes towards diesel engines. Therefore, European diesel engines can achieve a longer life than gasoline engines, but we can't. After all, in our life, we don't have the ideal conditions needed in theory!
Why is the theoretical life of diesel engines so long? The life of the engine has more to do with the design. When designers design, the calculated margin is enough, so the design service life is very long. However, the design service life does not mean that the engine does not need maintenance, it still needs maintenance, so the service life that most people understand refers to the service life without maintenance. In fact, replacing the piston cylinder liner belongs to the scope of maintenance, and the engine needs maintenance. Of course, many modern diesel engines can run millions of kilometers of maintenance-free mileage. This can only show that many years ago, the material technology has made great progress and the vehicle use environment has changed greatly. Driving on the highway has much less engine load than ordinary roads. So the use environment is also very important.
You'd better ask us three barrels of oil for this question, they have the most say! Just a few points, why heavy machinery is driven by diesel engine? Needless to say, the advantages are stable operation, low maintenance rate, high equipment reliability and high efficiency, but why not promote diesel engine in family cars? Because diesel oil is indispensable in important productivity, it is impossible to produce diesel oil without gasoline when refining crude oil. What about the gasoline produced? Another point is that because of technical barriers, our diesel refining level is really not good, and the quality of oil products is not as good as that of foreign countries. This is really not my worship of foreign things and flattery. Just pay attention to how dirty the air gun is at the gas station to refuel the diesel car. It is not the car that is dirty, but the quality of the oil. . .
A group of sprayers who haven't used several diesel engines are talking nonsense. The reason why the life of diesel engines in China is shorter than that of gasoline engines is only an emission standard of the Ministry of Environmental Protection.