高速汽油机的新型燃烧室(Ⅱ)

为解决小型高速汽油机低速时紊流强度低、燃烧过程不充分的难题，开发了一种新型燃烧室，该燃烧室已获得专利，它利用在活塞顶面的火花塞的远端和近端处设计的与缸盖形状相吻合的特殊突起，可在发动机压缩和膨胀过程中产生强烈的挤气旋流，将它应用在高速汽油机中，可明显提高低速时混合气的燃烧速率和火焰传播速率，从而全面改善内燃机的低速性能．实验研究表明，在压缩比和空燃比及点火提前角相同的条件下使用该燃烧室，与原机相比，尽管发动机的最大输出功率和转矩稍有下降，但最大转矩时的转速明显降低；转矩和燃油消耗率随转速降低明显改善，低速转矩最大提高率为8．4％，低速时燃油消耗的最大降低率为9．8％。

New Type of Combustion Chamber for High-Speed Gasoline Engines (Ⅱ)

A new type of combustion chamber is developed to increase turbulent intensity and improve combustion process at low speed for high-speed gasoline engines. The new combustion chamber has a specially designed shape on the top of the piston, where convex is far away from and concave near the spark plug. The shape on the piston top matches geometrical configurations of combustion chamber in the cylinder head and can generate strong squeezing motion of the mixture during compression and expansion strokes, resulting in much higher burning rate and flame propagating rate of the mixture and further significant improvement of the engine performance, especially at low speed. The experimental results under the condition of the same ignition advance angle, air-fuel ratio and compression ratio show that though there is a slight decrease in the maximum power output and torque of the engine, the speed of the maximum torque is reduced distinctly and the output torque and the fuel consumption can be improved significantly. The output torque can be increased by as much as 8.4% and the fuel consumption can be decreased by up to 9.8% at engine speed of 4 000 r/min.