Main curve may appear as parabola, ellipse, cubic polynomial, and trigonometric curves.Profiles with different main curve are compared one another at the same dimensions.

• 以抛物线、椭圆、三次曲线以及三角函数为例的研究表明，三次曲线构成的气缸型线具有最大的吸气容积而内容积比最小，适用于大排气量低压比的机器；