Car engines have multiple cylinders, how are these cylinders combined? Today we will discuss the layout of engine cylinders. Common arrangement types are in-line, V-shaped, horizontal opposite, etc., so what are the advantages and disadvantages of these arrangements?
First, in-line engines
The so-called in-line engine means that all cylinders are arranged side by side in a straight line. In-line is the oldest, the widest range of application of the cylinder arrangement form, its advantage is that the cylinder block and crankshaft structure is simple, only the use of a cylinder head can be, the manufacturing cost is low, high stability, low-speed torque characteristics are good; the disadvantage is that the engine is not suitable for high-speed operation, can not be increased by increasing the speed of the way to increase the power, so the total power is low, and can not be done too long, otherwise the engine rigidity can not be guaranteed, it is difficult to install on the car, and now the largest in-line engine is the inline six cylinders.
The number of cylinders in the mainstream in-line engine ranges from single cylinder to six cylinders, generally expressed by the letter L, followed by the number of cylinders, such as L3, L4, L5, L6 and so on. In our ordinary family cars, the most commonly used is the in-line four-cylinder engine. Among all the reciprocating piston engines, the best arrangement type is the in-line six cylinder, because it can self-balancing vibration, can achieve stable operation without a balance shaft, and the power output efficiency is high, the only drawback is that the engine rigidity is slightly worse. For example, on the most economically oriented trucks, almost all of them use inline six-cylinder diesel engines, which are the most stable and efficient engines.
Some people say that V6, V8, V12 are not as good as straight six? Not really. V6 and V8 must also have a balance shaft, otherwise they will also vibrate; and V12 is to combine two straight six engines together, a separate column straight six has no vibration, but the combination of the two cylinders together will have a little unbalanced force, so it will also vibrate slightly. However, the V-engine will be slightly stiffer than the straight-six engine.
Second, V-engine
The so-called V-type engine is to divide all cylinders into two groups, and arrange the adjacent cylinders together at a certain angle, so that the two groups of cylinders form a plane with an angle, and the cylinder is V-shaped from the side. The emergence of V-type engines is mainly to solve the problem of in-line engine length is too large, so its main advantage is that the height and length size are small, the weight is lighter, it is convenient for the engine compartment layout, the cylinder block rigidity is higher, it is possible to adapt to high-speed operation, you can increase the power by increasing the speed limit, and you can also use the expansion of the cylinder diameter to increase the engine torque; the disadvantage is that the structure is complex, it is not easy to maintain and repair, it is necessary to have two sets of cylinder heads and gas distribution mechanisms, the cost is higher, and the mechanical efficiency is not as good as the in-line engine. At the same time, there are many parts of the V-type engine, and the vibration and noise will also increase, except for the V12, there is no way to fundamentally eliminate the vibration.
The number of V-type engine cylinders is generally double, such as 2, 4, 6, 8, 10, 12, etc., which are represented by V2, V4, V6, V8, V10, and V12 respectively. There are also special 5-cylinder V-engines, such as Volkswagen's VR5 engine. V2 engine is generally used in motorcycles, V4 is relatively rare, other V6, V8, V10, V12, etc. are mostly used in more advanced models, such as Mercedes-Benz S, Audi A8, Bentley, Rolls-Royce and so on. Among them, the V10 is relatively rare, mainly used in some high-performance cars, such as Porsche Carrera GT, Audi RS6, BMW M5 and so on.
The cylinder angle of the V-engine is an interesting topic. The angle of the centerline of the two cylinders adjacent to the V-engine is called the cylinder angle. The main purpose of choosing the correct cylinder angle is to eliminate vibration, in general, the smaller the angle, the greater the vibration, but the smaller cylinder angle can obtain more powerful torque. In addition, different cylinder angles can also make the engine emit different exhaust sound waves.
Common cylinder angles are 60°, 72°, 90°, 120°, the general V6 engine cylinder angle is 60°, V8 engine cylinder angle is 90°, V10 engine cylinder angle is 72°, V12 engine cylinder angle is 60°. The 120 ° angle engine width is too large, rarely used; 72 ° angle is the V10 engine dedicated, its cylinder work interval angle is uneven, switch between 90 ° and 54 °; the crankshaft of the V8 engine has a cross crankshaft and a flat crankshaft, of which the cross crankshaft vibration is small, but the torque burst is slower, not suitable for high speed, the exhaust sound wave is not good, generally used for family cars, and the plane crankshaft vibration is slightly larger, the torque explosion is violent, the exhaust sound is beautiful, and it is more suitable for performance cars The cylinder angle of the V6 engine is generally 60°, and if in some cases it is necessary to install a larger element between the two columns of cylinders (Bill turbocharger), the cylinder angle needs to be increased to 90°.
There are two other special cases for V-engines: VR engines and W-engines.
The VR engine is a small angle V-type engine, its cylinder angle is very small (generally 15 °), the two cylinders are close to parallel, and the spark plug hole on the cylinder head is almost in a straight line. Common VR engines are six-cylinder, but there are also a small number of five-cylinder engines. VR engine structure is compact, only use a cylinder head, a set of camshafts can be done, its width is close to the in-line engine, the length is not much longer than the in-line engine, although the number of cylinders is larger, but the engine volume is smaller, very suitable for the front transverse engine platform, but there is a high demand for power models, such as volkswagen golf. But this engine is not a very good product, it is more like a compromise of the V engine and the in-line engine, the congenital vibration is strong, although the balance shaft is added, but the vibration is still much greater than the ordinary straight six and V6 engines. At present, this engine is mainly used by Volkswagen companies, but there are very few models on board.
The W engine is based on the VR engine, and the combination of two VR engines at a certain angle (usually 72°) becomes a W-type engine with four cylinders. The common W-type engine is Volkswagen's W12 engine, which is mounted on Volkswagen's Volkswagen Phaeton, Bentley Continental and Audi A8. In addition, there are old Passats that have been equipped with W8 engines, Bugatti's W16 engines, and so on. The advantage of the W-type engine is that it is compact, the length is shorter, it is more space-saving, and the gearbox can be equipped with a four-wheel drive system; the disadvantage is that the engine operation balance is poor and the vibration is larger, such as volkswagen's W12 engine, although it is designed with two counter-rotating balance shafts inside, but the vibration can still be felt.
Third, the horizontal opposing engine (H type)
The so-called "horizontal opposite" refers to the horizontal distribution of engine cylinders on both sides of the crankshaft. This type of engine, in fact, can be seen as a variant of the V-type engine, the V-type engine two rows of cylinders to the sides of the break, until the cylinder angle becomes 180 °, you get a horizontal opposing engine. This engine horizontal symmetrical arrangement of the cylinder is a symmetrical and stable structure, so its resonance is small, noise is small, good balance, good running smoothness, low center of gravity installed on the car, uniform mass distribution, can be designed to be flat and low, enhance the driving stability of the car, improve the car handling performance.
However, the manufacturing cost and process difficulty of this structure are quite high, the maintenance cost is relatively high, and it is not conducive to the layout of the engine compartment, and the problems of burning oil and cylinder partial grinding are difficult to solve, so the application is relatively small. At present, only Porsche and Subaru are insisting on using horizontal opposed engines, and other car companies have given up. This also shows from another side that the horizontal opposed engine is not as good as the ordinary in-line and V-type engines, and the "horizontal opposed engine is the best, and if you don't buy Subaru, you don't understand the car", which is actually just a ridiculous one-sided cognition.
In addition, there is a star engine. This kind of engine cylinder is based on the crankshaft as the shaft, arranged in a star shape, and the number of cylinders is mostly odd, such as 7, 9, 11 and so on. This engine is generally used in old-fashioned propeller aircraft, and some people have carried it on motorcycles, and it has now been completely eliminated. As for the rotor engine, it is structurally different from the reciprocating piston engine, and the cylinder arrangement and arrangement type are also different, which will not be discussed here.
To sum up, the engine cylinder arrangement type, whether in-line, V-shaped or horizontally opposed, is aimed at counteracting the vibration of a single cylinder when doing work through a reasonable arrangement. One of the most reasonable is the inline six-cylinder engine, but the length of this engine is too large to be mounted on many horizontal engine platforms; and for ordinary family cars, the inline four-cylinder engine is a very reasonable layout type; V-type engines are generally used in luxury cars, VR, W type is one of the special cases, let's take a look; as for horizontal opposition, if it is not very emotional, it is still avoided!