从而得到万有特性曲线
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表示内燃机全部负荷和转速范围内的运行特性的一种基本方法是在平均有效压 力-转速的图上绘制有效燃油消耗曲线。发动机被固定到测功机上，在整个负 荷和转速范围内，产生扭矩和燃油消耗量数据，从而得到万有特性曲线。
负荷特性和速度特性只能用来表示某一转速或某一油量控 制机构位置时，内燃机各种参数的变化规律，而内燃机特 别是车用内燃机的工况变化范围很广，要分析各种工况下 的性能，就需要多张负荷特性或速度特性图，这样既不方 便，也不直观。为了能在一张图上较全面地表示内燃机各 种性能参数的变化，经常应用多参数的特性曲线，这种特 性就是万有特性。 万有特性曲线一般是以转速n为横坐标，以负荷(平均有效 压力pme)为纵坐标。在图上绘出若干条等油耗曲线和等功 率曲线。两种类型内燃机典型的万有特性如图8—7所示。 根据需要，还可在万有特性曲线上绘出等节气门开度线、 等排放线、等过量空气系数线等。
(universal characteristics)
One common way to present the operating characteristics of an internal combustion engine over its full load and speed range is to plot brake specific fuel consumption contours轮廓 on a graph of brake mean effective pressure versus engine speed. Operation of the engine coupled to a dynamometer测 功器on a test stand, over its load and speed range, generates the torque and fuel flow-rate data from which such a performance map is derived.
Ch.7 Engine Operating Characteristics
Content
7.1 Engine performance parameters 7.2 Engine load characteristics 7.3 Engine speed characteristics 7.4 Diesel engine governing
a) CI engine
b) SI enwk.baidu.comine
Fig.7.12 Performance map for SI engine and CI engine
Figure 7.12 shows examples of such a performance map for a four-cylinder spark-ignition engine and compression-ignition engine. The upper envelope of the map is the wide-open-throttle performance curve for SI engine and rated condition performance curve for CI engine. Points below this curve define the part-load operating characteristics. While details differ from one engine to another, the overall shapes of these maps are remarkably similar. When mean piston speed is used instead of crankshaft speed for the abscissa, the quantitative定量的similarity of such maps over a wide range of engine sizes is more apparent.
图7.12表示的是四缸汽油机和柴油机万有特性示例。图的最上层分别是汽 油机的大开度节气门性能曲线和柴油机的标定条件下的性能曲线。该条线 以下的点定义了部分负荷运行特性。虽然每条线的细节不同，但是整体趋 势缺十分相似。当应用平均活塞速度而不是曲轴转速作为横坐标时，发动 机尺寸变化很大范围内的万有特性曲线的数量的相似性更明显。
characteristics柴油机的调速特性 7.5 Engine performance map (universal
characteristics)万有特性 Master: definition, The plotting steps
7.5 Engine performance map
The maximum bmep (Brake Mean Effective Pressure)
Maximum bmep occurs in the mid-speed range; the minimum bsfc island is located at a slightly lower speed and at part load. These map characteristics can be understood in terms of variations in
volumetric efficiency v , mechanical efficiency m , indicated efficiency i and the importance of heat
losses and friction change.
最大的平均有效压力出现在中等转速范围；最小的有效燃油消耗量位于部 分负荷时的较低转速区间。 这些特性曲线可以被理解成：充气效率、机械效率、指示热效率的改变， 以及热量损失和摩擦变化的重要性。
负荷特性和速度特性只能用来表示某一转速或某一油量控 制机构位置时，内燃机各种参数的变化规律，而内燃机特 别是车用内燃机的工况变化范围很广，要分析各种工况下 的性能，就需要多张负荷特性或速度特性图，这样既不方 便，也不直观。为了能在一张图上较全面地表示内燃机各 种性能参数的变化，经常应用多参数的特性曲线，这种特 性就是万有特性。 万有特性曲线一般是以转速n为横坐标，以负荷(平均有效 压力pme)为纵坐标。在图上绘出若干条等油耗曲线和等功 率曲线。两种类型内燃机典型的万有特性如图8—7所示。 根据需要，还可在万有特性曲线上绘出等节气门开度线、 等排放线、等过量空气系数线等。
(universal characteristics)
One common way to present the operating characteristics of an internal combustion engine over its full load and speed range is to plot brake specific fuel consumption contours轮廓 on a graph of brake mean effective pressure versus engine speed. Operation of the engine coupled to a dynamometer测 功器on a test stand, over its load and speed range, generates the torque and fuel flow-rate data from which such a performance map is derived.
Ch.7 Engine Operating Characteristics
Content
7.1 Engine performance parameters 7.2 Engine load characteristics 7.3 Engine speed characteristics 7.4 Diesel engine governing
a) CI engine
b) SI enwk.baidu.comine
Fig.7.12 Performance map for SI engine and CI engine
Figure 7.12 shows examples of such a performance map for a four-cylinder spark-ignition engine and compression-ignition engine. The upper envelope of the map is the wide-open-throttle performance curve for SI engine and rated condition performance curve for CI engine. Points below this curve define the part-load operating characteristics. While details differ from one engine to another, the overall shapes of these maps are remarkably similar. When mean piston speed is used instead of crankshaft speed for the abscissa, the quantitative定量的similarity of such maps over a wide range of engine sizes is more apparent.
图7.12表示的是四缸汽油机和柴油机万有特性示例。图的最上层分别是汽 油机的大开度节气门性能曲线和柴油机的标定条件下的性能曲线。该条线 以下的点定义了部分负荷运行特性。虽然每条线的细节不同，但是整体趋 势缺十分相似。当应用平均活塞速度而不是曲轴转速作为横坐标时，发动 机尺寸变化很大范围内的万有特性曲线的数量的相似性更明显。
characteristics柴油机的调速特性 7.5 Engine performance map (universal
characteristics)万有特性 Master: definition, The plotting steps
7.5 Engine performance map
The maximum bmep (Brake Mean Effective Pressure)
Maximum bmep occurs in the mid-speed range; the minimum bsfc island is located at a slightly lower speed and at part load. These map characteristics can be understood in terms of variations in
volumetric efficiency v , mechanical efficiency m , indicated efficiency i and the importance of heat
losses and friction change.
最大的平均有效压力出现在中等转速范围；最小的有效燃油消耗量位于部 分负荷时的较低转速区间。 这些特性曲线可以被理解成：充气效率、机械效率、指示热效率的改变， 以及热量损失和摩擦变化的重要性。