Number of cylinders (a)

This data refers to each engine containing several cylinders.

Little knowledge: What is a cylinder?

Definition: The cylindrical chamber in the engine has a piston that is pushed by the pressure or expansion force of the working fluid, and a similar but non-cylindrical part in some special engines.

The number of cylinders commonly used in automobile engines is 3, 4, 5, 6, 8, 10, and 12 cylinders. Engines with a displacement of less than 1 liter are commonly used for 3 cylinders (such as Xiali 7100), 1-2.5 liters are generally 4-cylinder engines, 3 liters or less are generally 6 cylinders, 4 liters are 8 cylinders, and 5.5 liters or more are 12-cylinder engines. . According to the arrangement of the engine, it can be divided into W-type 12-cylinder engine (such as the Volkswagen Phaeton W12, Audi A8W12), V-type 12-cylinder engine (such as the Mercedes-Benz S600, BMW 760), W-type 8-cylinder engine (such as Passat W8) , V-type 8-cylinder engine (such as the new Audi A6L4.2), horizontally opposed 6-cylinder engine (such as Subaru Forester), V-type 6-cylinder engine, inline 5-cylinder engine and inline 4-cylinder engine. In general, under the same cylinder diameter, the more the number of cylinders, the greater the displacement, the higher the power; Under the same displacement, the more the number of cylinders, the smaller the bore diameter, the speed can be increased to obtain a larger power.

In general, in the case of the same displacement, the more valves, the better the intake and exhaust efficiency. Just like a person running, when he is tired and breathless, he needs to open his mouth to breathe. The traditional engines are mostly one intake valve and one exhaust valve per cylinder. This two-valve gas distribution mechanism is relatively simple, the manufacturing cost is low, and maintenance is relatively easy. For an ordinary engine with a low output power requirement, two valves can achieve satisfactory engine output power and torque performance.

Large-displacement, high-power engines use multi-valve technology. The simplest multi-valve technology is the three-valve structure, which is based on an intake valve and a two-valve structure. In recent years, most of the cars newly developed by major automobile companies in the world have adopted the four-valve structure. In the four-valve gas distribution mechanism, each cylinder has two intake valves and two exhaust valves.

The four-valve structure can greatly improve the efficiency of the engine's intake and exhaust, and most of the new cars use four-valve technology. Of course, Volkswagen uses five-valve technology, such as the old Jetta's 20V engine, and the Bora 1.8T engine is also a five-valve.

However, reaching or exceeding the six-valve not only makes the gas distribution structure too complicated, but also leads to shortened engine life, and the space curtain area (valve circumference and valve lift) for valve opening is also small, resulting in reduced efficiency. Therefore, four-valve technology is currently used most commonly.

It should be pointed out that the number of cylinders and valves can be used as one of the criteria for judging the pros and cons of the engine, but it is not the only standard. For example, the 1.8T 4-cylinder with turbocharging technology can achieve the same level of power and torque as an ordinary six-cylinder machine.