1. Number of cylinders (a)
This data refers to an engine comprising several cylinders of each.
Tips: What is a cylinder?
Interpretation: a cylindrical vacuum chamber in the engine, which has an urging force by the pressure or expansion of the working fluid of the piston, similar, but non-cylindrical portion in the special engine.
Number of cylinders commonly used in automobile engine has 3,4,5,6,8,10,12 cylinder. Displacement of one liter or less common three-cylinder engine (e.g., leased 7100), usually 1-2.5 liter 4-cylinder engine, the engine is generally about 3 liters of 6-cylinder, 8-cylinder is about 4 liters, 5.5 liters 12-cylinder engine . According to the arrangement of the engine, it can be divided into 12-cylinder engine with a W-type (e.g. Phaeton W12, Audi A8W12), V-type 12 cylinder engine (e.g., S600 Mercedes, BMW 760), W-type 8-cylinder engine (e.g., Passat W8) , V-type 8-cylinder engine (such as the new Audi A6L4.2), horizontally opposed 6-cylinder engine (e.g., Subaru Forester), V-type 6-cylinder engine, an inline five-cylinder engine and a 4-cylinder inline engine or the like. In general, in the same bore, the more the number of cylinders, the greater the displacement, the higher power; in the same displacement, the more the number of cylinders, the smaller the bore, the rotational speed can be increased to obtain a larger increase power.
In general, the same displacement, the more the valve, the better intake and exhaust efficiency, like a person running, when tired out of breath, need to open mouth breathing. Is a conventional engine with intake valve and one exhaust valve per cylinder, the two gas distribution valve mechanism is relatively simple, low cost, relatively easy to repair. For ordinary engine output is not too high, two valves can be obtained satisfactory performance of the engine output power and torque.
larger displacement, the larger the engine power to multi-valve technology. The simplest technique is three-valve multi-valve structure, i.e., a plus intake valve into a row of a two-valve structure basis. In recent years, worldMajor car companies to develop new cars use a four-valve structure. Four-valve gas distribution mechanism, each of the cylinders have two intake valves and two exhaust valves.
four-valve structure can greatly improve the engine intake, exhaust efficiency, most new cars four-valve technology. Of course, Volkswagen with five multi-valve technology, such as the old models Jetta 20V engine, Polaris 1.8T engine is five valves.
However, to achieve not only the valve or more than six gas distribution structure is too complicated, but also lead to reduced engine life, valve open space blind area (and circumference of the valve lift of the valve) is small, efficiency is lowered. Therefore, four-valve technology is currently the most widely used.
It should be noted that the number of cylinders and valves of the engine can be determined as one of the merits of the standard, but not the only criterion. For example, with turbocharging 1.8T 4-cylinder engine power and torque can reach the level of ordinary 6-cylinder machine.