HOLLOW ENGINE VALVE

The invention provides a hollow engine valve which suppresses increase of manufacturing cost and has high durability. The hollow engine valve comprises a valve body. A bottomed hollow hole is formed throughout the valve head part and a valve shaft part connected with the valve head part of the valve main body. The hollow engine valve is characterized in that the bottom surface of the air valve head part is a plane or a concave surface, the bottom surface of the hollow hole is an inverted conical concave surface with a vertex angle of 140-178 degrees, and the inner diameter of the bottom surface of the hollow hole is larger than the inner diameter of the valve shaft part of the hollow hole. 本发明提供一种抑制制造成本的增大且耐久性高的空心发动机气门。空心发动机气门具备气门主体，该气门主体遍及气门头部和与该气门头部连接的气门轴部而形成有有底的空心孔，其特征在于，上述气门头部的底面为平面或凹面，上述空心孔的底面是形成为顶角为140°以上且178°以下的倒圆锥状的凹面，且上述空心孔的底面的内径比上述空心孔的上述阀轴部的内径大。