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首页> 外文期刊>Fortschritt-Berichte VDI, Reihe 12. Verkehrstechnik-Fahrzeugtechnik >Differentiated Analysis of Downsizing Concepts
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Differentiated Analysis of Downsizing Concepts

机译：精简概念的差异分析

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Applying downsizing, a given naturally aspirated engine is replaced by a boosted engine having a smaller displacement. In the past downsizing was mainly used for increasing maximum performance. Nowadays reducing fuel consumption by downsizing gains increasing importance for fuel economy. The detailed analysis of fuel consumption maps showed the brake specific fuel consumption of a turbocharged engine is higher compared with a naturally aspirated engine on equal brake mean effective pressure (bmep) basis. Only if a naturally aspirated engine and a downsized turbocharged engine are compared at the same torque level, the turbocharged engine can prove better fuel consumption in the low to mid torque range of the engine map. The reason for that is that the engine with the smaller displacement is operated at a higher bmep, which is inversely proportional to the displacement. This beneficial area grows as the difference in displacement becomes bigger. A downsizing factor (displacement of NA engine divided by displacement of turbo engine) of at least 1,4 is recommended. In order to achieve also in vehicle a significant fuel consumption improvement, the overall transmission gear ratio needs to be decreased. This approach can be justified, since rated engine speed of a turbo engine is generally lower than that of a naturally aspirated engine while the torque plateau of the turbo engine is higher and wider than that of the NA engine of equal maximum power, despite the maximum gear ratio for turbo engines is limited by requirements regarding take-off and drive quality. Downsizing should not be limited as just an engine concept; it really is a match of a synergistic combination of a boosted engine and a long gearing transmission to a right-sized vehicle. Under comparable conditions fuel consumption can be reduced by as much as 11%. But, this advantage gets smaller as the weight of the vehicle increases.
机译：应用小型化，将给定的自然吸气发动机替换为具有较小排量的增压发动机。过去，缩小尺寸主要用于提高最大性能。如今，通过缩小尺寸来减少燃油消耗对燃油经济性越来越重要。燃油消耗图的详细分析显示，在平均制动平均有效压力（bmep）的基础上，涡轮增压发动机的制动比油耗要高于自然吸气发动机。只有在相同的扭矩水平下比较自然吸气发动机和小型涡轮增压发动机，涡轮增压发动机才能在发动机图的中低扭矩范围内证明更好的燃油消耗。其原因在于，排量较小的发动机以较高的bmep运行，该bmep与排量成反比。随着位移的差异变大，该有益区域也会增加。推荐缩小尺寸系数（NA发动机的排量除以涡轮发动机的排量）至少为1.4。为了在车辆中也实现显着的燃料消耗改善，需要减小整体传动齿轮比。这种方法是合理的，因为涡轮发动机的额定发动机转速通常低于自然吸气发动机的额定转速，而涡轮发动机的扭矩平稳期却比最大功率相同的NA发动机的扭矩平稳期更高和更大，尽管最大涡轮发动机的齿轮比受起飞和驱动质量要求的限制。缩小规模不应该仅仅局限于引擎概念。实际上，这是增压发动机和长齿轮传动到适当尺寸车辆的协同组合的匹配。在可比的条件下，燃油消耗最多可减少11％。但是，随着车辆重量的增加，这种优势变得越来越小。

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