In Vietnam in particular and in developing countries in general, cars still occupy a high proportion of the total means of transportation of people, and forecast that in the coming years, this proportion is still quite good. high.
As one thing we realize, motorcycles only use gasoline engines, in which diesel engines (also known as diesel engines) are more efficient than gasoline engines, diesel fuel prices are cheaper. Gasoline and diesel will not burn at normal temperature, so it will be less dangerous than gasoline. In addition, diesel engines are less likely to fail because they do not have ignition and carburetors, etc. Generally speaking, diesel engines have more advantages than gasoline engines, but why do they manufacture them? Not installing the oil engine on motorbikes?
What are some of the main reasons that diesel engines are not used on motorcycles? It is not said that it is not used properly because in the past there were also models equipped with diesel engines but now it is difficult to produce a motorbike using diesel engine. The main reasons:
- To - Heavy - Bulky
Because the diesel engine operates on the principle that the air is compressed at high temperature and pressure, then new diesel fuel is injected into the combustion chamber, then under such high pressure and temperature, diesel oil. self-igniting and generating, but it does not need ignition systems like gasoline engines, so it needs a very high compression ratio, usually the compression ratio of oil engines is about 15-24, while for engines gasoline engine is only 8-13.
Compression ratio: when the bittong is operating in the cylinder, it has 2 limit positions: upper die position (DCT) and lower die position (CD), when the bittong is in the lower die position, the volume of At that time, the combustion chamber was the largest (Vmax), when the bittong went up to the upper dead point, the volume of the combustion chamber was now the smallest (Vmin). Compression ratio = Vmax / Vmin. Thus, in order to have a high compression ratio, the volume of the bittong at the lower dead point must increase, when that volume is increased, one can increase the diameter of the cylinder or increase the length. of the cylinder, so it will result in an increase in size and an increase in the weight of the diesel engine, which is why the same power is generated because the diesel engine is always heavier or is bigger than the gasoline engine. Therefore, integrating an engine that is so big on a small motorbike will not be suitable for us to use a gasoline engine.
- More vibration - More noise
Due to the high compression ratio of the diesel engine, the length of the cylinder increases, as the length of the cylinder increases, it will lead to the upper arm and the length of the crankshaft will increase. . Mechanically, the diesel engine's piston will fluctuate in a wider range than the gasoline engine, so it will be more vibration and noise than the gasoline engine. Today's cars have technologies that can handle this high vibration and noise, but to handle this noise of diesel engines mounted on motorcycles or small cars is very is problem.
- High price.
The price of a diesel engine and its repair cost will be higher than that of a gasoline engine. Because the diesel engine operates at high temperatures and pressures, the materials that make up a diesel engine need to be better and more durable than a gasoline engine. Secondly, while the structure of an oil engine is simpler than that of a gasoline engine, some parts and details require more precision, such as the engine's fuel injection system. its oil requires more precision and sophistication, so it is also more expensive than the ignition system on gasoline engines.
- Motorcycles need more power than torque.
Due to the nature of the structure of the oil engine, when operating, the piston will have to operate over a longer distance, so the hand and crankshaft have a longer length of the gasoline engine, then the traction Or more accurately, the torque of an oil engine will be greater than that of a gasoline engine, but the acceleration of the oil engine will be lower than that of a gasoline engine, ie its capacity is lower than that of a gasoline engine. In general, the diesel engine will be more suitable for large vehicles that need large traction, such as trucks, large SUVs; As for small cars or motorcycles, it is not suitable, especially for motorcycles, motorcycles, it needs more acceleration than traction.
- Need an efficient cooler.
The diesel engine operates at high pressure and high temperatures, so its cooling mode needs to be better than the gasoline engine, if the heat dissipation problem for the oil engine is good, the engine is quite rough. bulky and the cost greatly increased.
- High technical requirements.
A diesel engine without a spark ignition system is like a gasoline engine, or it doesn't have a carburetor like a petrol engine, but the fuel pump system for diesel engines is usually more expensive. Gasoline engines are therefore more cost effective.
- It is difficult to start when it is cold.
Nowadays, oil engines want to work well in extreme weather conditions, especially when the weather is cold, oil engines are often difficult to start, so on modern cars, they have drying systems. air for warming up during start-up, if such a set is installed for a motorcycle, it is not suitable because a motorbike is a vehicle that is cheap and meets the majority of consumers. used, so wanting an oil engine to operate optimally on a motorbike but needing to install so many things, it was unreasonable in terms of cost, not to mention that it would make The engine system is more bulky and more complicated.
- A booster is needed.
Now that diesel engines want to run efficiently, automakers often have turbochargers to inject more air into the cylinder to increase the efficiency of burning fuel, if such things are integrated. it will be very bulky but the price is quite high, particularly the turbocharger has a relatively high price.
- Toxic emissions.
One reason that can be said for developed countries but Vietnam does not require very strict is that oil engines emit more toxic fumes than gasoline engines so in some countries have high requirements on the Law on Environment If the engine is to be used on vehicles, the engine needs a catalyst, and if the engine is to be installed on a motorcycle, it is not appropriate.
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