The cylinder block of current gasoline engine is divided into cast iron and cast aluminum. In diesel engine, cast iron cylinder block occupies the majority. The use of cast aluminum cylinder block, can reduce the weight of the engine, play the role of energy saving. Today's car manufacturers often use the "all aluminum engine" as the highlight of their advertising. What are the characteristics of aluminum and cast iron engines?
Advantages of aluminum:
From the use point of view, the advantages of the cast aluminum cylinder is light weight, by reducing the weight to achieve oil saving. In the same displacement of the engine, the use of aluminum block engine, can reduce the weight of about 20 kilograms. For every 10 per cent reduction in the car's weight, fuel consumption can be reduced by 6 to 8 per cent. According to new data, foreign cars themselves weigh 20 to 26 percent less than they used to. The focus, for example, is made of all-aluminum alloy, which reduces the weight of the car, increases the heat dissipation of the engine, improves its efficiency and extends its life. From the point of view of fuel saving, the advantages of cast aluminum engine in fuel saving have attracted much attention.
In addition to the difference in weight, there are many differences between the cast iron block and the cast aluminum block during the production process. Cast iron production line covers a large area, causes great environmental pollution, and has complex processing technology. The production characteristics of cast aluminum cylinder block are exactly the opposite. From the market competition point of view, cast aluminum cylinder block has certain advantages.
Advantages of iron:
Iron and aluminum have different physical properties. The cylinder block of cast iron has a stronger thermal load capacity and has a greater potential in terms of engine power. For example, a 1.3-liter cast iron engine can produce more than 70kW of power, while an aluminum engine can produce only 60kW. It is understood that 1.5-liter cast iron engine through turbocharging and other technologies, can achieve the 2.0 liter engine power requirements, and cast aluminum cylinder engine is difficult to achieve this requirement. So a lot of people in the low speed driving focus can also break out a surprising torque output, not only conducive to the car's start, accelerate, but also early to achieve the shift, to achieve fuel efficiency.
The aluminum cylinder block engine still has a part of the internal use of cast iron materials, especially the cylinder, to use cast iron materials. The thermal expansion rate of cast aluminum and cast iron is not uniform after fuel combustion, which is the problem of deformation consistency. When the engine is in operation, the cast aluminum cylinder block engine equipped with cast iron cylinder shall meet the sealing requirements. How to solve this problem is a special concern of the casting aluminum cylinder enterprises.
Disadvantages of aluminum:
1.Volume
Because the specific gravity of aluminum is lighter, the structural strength of aluminum per unit volume is smaller than that of cast iron, so the volume of aluminum cylinder block is usually larger than that of cast iron, and it is difficult to achieve the compact and small volume of cast iron cylinder block.
2. Corrosion resistance and strength
Aluminum is known to react chemically with the water produced during combustion, so it is far less resistant to corrosion than iron cylinder blocks, especially supercharged engines that require higher temperature and pressure. In addition to the conclusions about volume that have been made, it is difficult to achieve the strength of the cast iron cylinder block with an aluminum cylinder block when the engine size of the car is small. Therefore, the high pressure engine mostly USES the cast iron cylinder block. In these two respects, all aluminum engine is inferior to cast iron cylinder block engine apparently.
3. Friction coefficient of the engine
Today's car engines, in order to reduce the inertia of the reciprocating parts, usually increase the speed of rotation and response, and the pistons are mostly made of aluminum alloy. If the cylinder wall is made of aluminum. The coefficient of friction between aluminum and aluminum is relatively large. For this reason, the performance of the engine will be greatly affected, on the contrary, the cast iron engine will not produce such problems, so in this respect, cast iron cylinder block is better than all aluminum engine.
Cylinder head is the advantage of aluminum alloy:
Need to explain is, the enterprise often said all aluminum engine is refers to the cylinder head and cylinder block are aluminum alloy engine. The cylinder head is aluminum alloy, the cylinder block is cast iron engine, still known as the cast iron engine. But in fact, many years ago, car manufacturers began to use aluminum cylinder heads on a large scale. Since the head itself is not heavy, carmakers are keen not on its light weight but on its heat dissipation. With the rapid development of engine technology, four-valve structure has become the main trend of engine design. Compared to a two-valve engine, a four-valve cylinder head produces more heat per cylinder than a two-valve head, so an all-aluminum head is a good solution.
For cost reasons, it was much later to adopt an all-aluminum design for the cylinder block than for the cylinder head. The cylinder block is the heavy part of the engine, so the aluminum alloy material can reduce the weight of the engine, so as to achieve the goal of reducing the weight of the whole vehicle. This is particularly valuable for front - drive cars. However, little expect, material qualitative change needs the expenditure of more cost, as a result of the difference of material price and processing craft, the engine that USES aluminium alloy cylinder block is met naturally than the price of cast iron engine wants a higher. In this demand point, it is obvious that the engine of cast iron cylinder block dominates.
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