28.充钠排气门 对于热负荷特别高且尺寸较大的排气门,可以作成中空,在其中充填金属钠。钠在常温下呈固态,而在气门工作温度下呈液态,气门运动时,液态钠强烈晃动,使气门头热量传向杆部,再经导管传向冷却水。29.气门头部的几种型式 通常有3种型式:1)平面头部,结构简单,加工方便,受热面小,重显轻;2)凸面头部,刚度好,凸起部分的流线能适应排气气体流动;3)凹面头部,可以减轻重量。 28. Soda Exhaust Valve Exhaust valve with a particularly high thermal load and large size can be hollow and filled with metallic sodium. Sodium is solid at room temperature and liquid at the valve operating temperature. When the valve is in motion, the liquid sodium is strongly shaken, causing the heat of the valve head to pass to the rod and then to the cooling water via the conduit. 29. Several types of valve head usually have 3 types: 1) plane head, simple structure, easy processing, heating surface is small, light weight; 2) convex head, stiffness, convex part of the streamline Can adapt to the exhaust gas flow; 3) concave head, you can reduce the weight.