三轮摩托车中置自然风冷发动机的设计

驾驶室型正三轮摩托车中置自然风冷型发动机设计方案还不够成熟，发动机台架试验及车辆道路试验数据均表明该类车型的发动机缸头及机油温度过高，散热困难，导致了发动机输出功率及转矩降低，使用寿命也较短。选择强制风冷发动机来代替自然风冷发动机，由于低速大转矩的特点，会增加车辆的燃油消耗及尾气排放，同时使车辆的加速及超越加速性能大大降低。

The Design of the Centrally-placed Naturally Air-cooled Engine for Three-wheeled Motorcycle

Up to now, the design of the centrally-placed naturally air-cooled engine for three-wheeled motorcycle is not mutured. The data of the engine bench test and the road test of motorcycle show that the temperature of this kind of engine, head and the oil is over high and is difficult in heat dissipation, which leads to the reduction of engine output power and the torque, and to shorter service life as well. In case that forcedly air-coiled engine is selected for substituting for naturally air-cooled engine, because of the characteristics of low speed and big torque, the fuel consumption and emissions will be much more and the acceleration and passing acceleraton of the motorcycle will be greatly reduced.