Engine material, usually people often talk about the main cylinder block and cylinder head materials, such as often said all-aluminum engine, means that the cylinder block and cylinder head are cast with aluminum alloy. All-aluminum engine block is naturally made of aluminum, in fact, not all right. Most of the "all aluminum" engines also need to use cast iron cylinder liners, xinyuanzhu group combined with the process characteristics of cast iron and cast aluminum parts, production costs to make the following summary.
1、aluminum cylinder block and cast iron cylinder block advantages and disadvantages of each.
The specific gravity of aluminum is lighter than cast iron, under the premise of meeting the strength requirements, aluminum cylinder block is much lighter. Engine light, you can play a positive impact on the weight distribution of the whole car, the whole car mass is also lighter. So, this point on the aluminum cylinder block advantage.
For the same reason, the specific gravity of aluminum is light, the strength of the aluminum structure per unit volume is less than cast iron, so the aluminum cylinder block is usually larger, excluding the cooling water channel is actually quite thin cylinder wall. Thus, the whole engine is very compact, small volume. Aluminum block is harder to achieve this effect. This point on the cast iron cylinder block advantage.
1.3 corrosion resistance and strength
Aluminum and combustion water chemical interaction, corrosion resistance is not as good as the cast iron block, especially for the temperature and pressure are higher supercharged engine is so. and the previous conclusion about the volume, in turn, when your engine volume requirements are relatively small, the use of aluminum block is usually difficult to achieve the strength of cast iron block. So a lot of high boost engines use cast iron block, it is always cast iron block. If you use an aluminum block, it''s basically less easy. This point on the cast iron block has the advantage.
Naturally, the cost of aluminum block is more expensive, which is the advantage of cast iron block.
1.5 Explosion resistance
Aluminum has faster thermal conductivity, so the cooling performance is good, which can help the engine reduce the probability of abnormal combustion, the same compression ratio, aluminum block engine can use lower grade gasoline than cast iron block engine. This point on the aluminum cylinder block advantage.
1.6 Friction coefficient
Nowadays, in order to reduce the inertia of the reciprocating parts and improve the speed and response, most of the pistons use aluminum alloy as the material. If the cylinder wall is also aluminum. The coefficient of friction between aluminum and aluminum is relatively large, so that the engine performance is greatly affected. Cast iron does not have such a problem. This is the cast iron cylinder block advantage.
All aluminum engine block is not necessarily "all aluminum". In order to overcome these disadvantages, aluminum cylinder block usually have to use cast iron or steel cylinder liner. If you remove the cooling water channel and cast iron cylinder liner, then the aluminum cylinder wall is not too thin, and gray cast iron, in fact, is much lighter than the usual cast iron. True all-aluminum, no cast iron or steel cylinder liner, because it uses silicon aluminum alloy in the cylinder wall part to overcome the disadvantages mentioned earlier. It is then lighter than the normal aluminum cylinder block. and this process is very expensive, this technology is also difficult to withstand the working environment after supercharging, the current supercharged engine, even if the aluminum block, there must be cylinder liners, so if the ordinary structure of the aluminum block, then the weight savings will not exceed 10kg, but the volume will be larger. and the total weight is only 150+kg, so the weight reduction of not more than 10kg does not seem to be significant. On the contrary, it makes more practical sense for a cast iron block to produce a higher boost limit.
Gasoline engines have two types of blocks, cast iron and cast aluminum. In the diesel engine, cast iron block accounts for the majority. In recent years, with the rapid development of the automobile industry, cars quickly into the lives of ordinary people, at the same time, the vehicle''s fuel-saving performance is gradually paid attention to. Reduce the weight of the engine, can save fuel. The use of cast aluminum cylinder block, can reduce the weight of the engine.
From the point of view of use, the advantage of cast aluminum cylinder block is light weight, by reducing weight to achieve fuel savings. In the same displacement of the engine, the use of aluminum block engine, can reduce the weight of about 20 kg. Every 10% reduction in the weight of the car itself, fuel consumption can be reduced by 6% to 8%. From the perspective of fuel saving, the advantages of cast aluminum engines in terms of fuel saving are quite popular.
In addition to the weight difference, in the production process, cast iron block and cast aluminum block also have a lot of differences. Cast iron production line covers an area of large, environmental pollution, complex processing; while the production characteristics of cast aluminum block is the opposite. From the point of view of market competition, cast aluminum cylinder has certain advantages. The price of aluminum in the market is not low, which undermines the advantages of cast aluminum block engine in the production and processing.
The physical properties of iron and aluminum are different. A cast iron block has a much higher heat load capacity and has more potential in terms of engine lift. For example, a 1.3-liter displacement cast iron engine output power can exceed 70kW, while a cast aluminum engine output power can only reach 60kW. It is understood that 1.5-liter displacement cast iron engine through turbocharging and other technologies, can reach the power requirements of 2.0-liter displacement engine, while the cast aluminum block engine is difficult to meet this requirement.
2、aluminum block engine internal still part of the use of cast iron materials, especially the cylinder, to use cast iron materials. Cast aluminum and cast iron in the fuel combustion after the thermal expansion rate is not uniform, which is commonly known as the deformation consistency problems, which is cast aluminum cylinder in the casting process a difficult problem. In the engine work, with a cast iron cylinder cast aluminum block engine to meet the sealing requirements. How to solve this problem, is the cast aluminum cylinder block business is particularly concerned about the problem.
2.1 All-aluminum engine in material, heat dissipation and other aspects is indeed better than cast iron engine, but more often than not, all-aluminum engine is not as good as compared to cast iron engine.
2.2 Volume. Because the specific gravity of aluminum is lighter, so the structural strength per unit volume of aluminum is less than cast iron, so the volume of aluminum block is usually larger than cast iron, it is difficult to achieve the compactness and small volume of cast iron block.
2.3 corrosion resistance and strength. As we all know, aluminum is easy to chemical reaction with the water generated by combustion, therefore, the corrosion resistance is far less than cast iron block, especially for the temperature and pressure are higher requirements of the supercharged engine is so. In addition to the already stated conclusion about the volume, therefore, when the engine volume of the car requires less, it is difficult to use aluminum block to achieve the strength of cast iron block. Therefore, most of the highly supercharged engines use cast iron blocks. In these two aspects, all-aluminum engine is obviously inferior to cast iron block engine.
2.4 engine friction coefficient. Now the car engine, in order to reduce the reciprocating motion of the parts inertia, usually improve the speed of rotation and response, the piston also mostly use aluminum alloy as material. If the cylinder wall using aluminum material. The coefficient of friction between aluminum and aluminum is relatively large. For this reason, the engine performance will be greatly affected, on the contrary, cast iron engine will not produce such a problem, so in this regard, cast iron cylinder block is also better than the all-aluminum engine.
To sum up.
All-aluminum engine refers to the cylinder head and cylinder block are made of aluminum alloy engine. The cylinder head is aluminum, the cylinder block is cast iron engine, is still called as cast iron engine. But in fact, as early as many years ago, car manufacturers'' engines have been used on a large scale all-aluminum cylinder head. Since the cylinder head itself does not weigh much, so car manufacturers are keen on it not because of its light weight, but because it has good heat dissipation performance. With the rapid development of engine technology, four-valve structure has become the mainstream engine design trend. Compared with two-valve engines, four-valve cylinder heads per cylinder generate more heat than two-valve cylinder heads per cylinder, so the use of all-aluminum cylinder heads is the best solution.
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