The desire of the drafters of the engine after changing the volume ratio between the engine operati

The desire of the drafters of the engine after changing the volume ratio between the engine operation is the same almost as much as the engine itself compressor and famous are also a number of experiments on this subject. The aim is, of course, in this case, improving the performance of the internal combustion engine - in the beginning it was more or less to increase its capacity, compressor but today see this as a good potential to reduce fuel consumption and carbon dioxide emissions.
What it means changing the volumetric ratio of the engine? Volume ratio is the ratio of the cylinder displacement and volume that remains after the piston stops at top dead center and denoted by the Greek letter e. A further question is, of course, what does this have to do with the efficiency ratio of the engine more precisely compressor the thermal efficiency of the engine - ht, which is expressed in the form of well-known 1-1/ec ht = -1, where c represents the exponent izentrope or the ratio of specific heats. Without too much explanation can be seen: the greater the ratio, the greater the yield and vice versa. Gasoline engine relationship can not be arbitrarily compressor increased, since we can achieve a situation where it starts to appear improper combustion - knocking. Knocking noise occurs compressor in a full-throttle or less intense but nothing in the partially open luputi. But when partially open hatch gets less air in the cylinder due to increased air resistances on the way to the cylinder.
How much air is brought into the cylinder, describes the volumetric efficiency of filling the cylinder, which is the ratio between compressor the actual amount of air in the cylinder and the theoretical amount of air, which in given conditions can be filled cylinder. After a small amount of cylinder (partially open butterfly Louta), compressor reducing the chance compressor of knock and vice versa (fully open throttle). Consequently, a smaller engine at higher filling ratio of the volumes and at higher load, the lower the ratio. However, the average loading of the automotive engine 20 to 30%, it was not possible compressor most of the time setting to a higher ratio. Such a setup allows higher engine efficiency and lower fuel consumption and CO 2 emissions.
The possibility of changing the volume ratio is of special interest in reducing prosotornine engine ("downsizing"), which is added to the pressure compressor charging roller. Despite having a smaller volume compressor so these engines of the same power as larger, while it should reduce the volume ratio, which is not conducive to certain characteristics of the engine. It is because compressor this would mean changing the ratio of the volumes of a particular solution. compressor
The strategy of changing the volumetric ratio is guided by filling pressures and pressures in the cylinder. The higher pressures of the filling of the cylinder, the lower should be the ratio, on the other hand, would be at lower pressures the charging ratio increased. When you start the relatively small value of the relationship in order to facilitate compressor starting the engine, as well as small proportions in relatively rapid opening of the throttle. When the driver decides to drive steady, the ratio increases. When the driver compressor accelerates sharply, compressor supply pressure increases, the rate decreases. Speed change ratio should be in the rise relatively fast (to happen must happen in less than 1/10 of a second) since the driver is detected by a delayed reaction, which is similar to the delay when the turbocharger does not reach the required filling compressor pressure. In the opposite change, it is fading, but the rapid change of the reduction compressor ratio is required. When adjusting the ratio change is necessary sensor for knocking together in a closed loop, as in this case, to reduce the backlog loop in the shortest time.
Rapid changes in the ratio required in the movements more energy, but it can be a suitable structure is obtained from the working cycle of the engine. However, since such a solution is expensive, it would still be paid off solutions with only a changeable ratio specified maximum and minimum. Nevertheless, in practice still possible to achieve most of the objectives and advantages offered by the federal variable manner.
Engines with variable volumetric ratio have in real life greater efficiency, in addition, such a solution is complemented with an overpressure polnjenjm, providing reliable emission reductions and improve the efficiency of the vehicle. Upcoming Technologies starter / generator that provides additional electric compressor drive at low loads, it is still one of the measures together in conjunction with turbocharger and variable ratio allow further improvement of the internal combustion engine.
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