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Direct Petrol Injection 2009

In the meantime, the Piezo-technology is also available for the direct-petrol-injection. The maximum pressure still stands at about 200 bar. In contrast to the first Piezo-diesel generation, there is no hydraulic transformation. Nonetheless the Piezo crystals do not have a direct effect on the opening mechanism. In this case, the hydraulic coupling has rather the job of providing a compensation, e.g., in the warming of the entire mechanism. A comparison with the hydraulic valve clearance compensation would not be that far off the mark.

An interesting factor is the quantity control, which is no longer exclusively initiated through the change in injected fuel. With the inlet manifold injection the end of supply at full load, can in principle, be moved so far back that it meets the injection begin. This would then be in fact, a continuous injection. This is not possible with the direct injection. To utilise the relatively shorter timing, the beginning of supply is also incorporated.

Actually the tendency towards downsizing in modern engines is posing more problems for the engineers. It's all about the spreading of the idle running amount, with 1-2 milliseconds injection time, right up to full load. The engines have a lower consumption, but at the same time, possibly more maximum performance. If, at the same time the available degree of the crank angle shrinks, one can envisage the problems that arise e.g., with the dimensioning of the intake diameter. The range between minimum and maximum injection increases. 07/10