改变行程的原因传统功率输出的控制虽然有效而精确,但从理论上讲还不是最好的。一般发动机的工作循环在最罕见工况,即节气门全开时效率最高。不需要最大功率时,节气门的作用是减低进气压力,但循环效率也随之降低。例如,在典型经济负荷时,进气终了压力只有三分之一大气压。与下列事实相对比,从热力学的观点来看,在发动机的整个工作范围内,主要使用大气 Reasons to change the course Although the control of the traditional power output is effective and accurate, but in theory it is not the best. The general engine working cycle in the most common conditions, that is, the most efficient when the throttle fully open. When maximum power is not needed, the throttle’s role is to reduce the intake pressure, but the cycle efficiency is also reduced. For example, at typical economic loads, the end-of-inlet pressure is only one-third of the atmospheric pressure. In contrast to the fact that, from a thermodynamic point of view, the atmosphere is mainly used throughout the working range of the engine