求翻译：针阀座的座面角为58030而针阀的锥角为600(少数有900的)。角度之间的这种微小差异，可以使针阀和针阀体的座面接触为“线接触”，要求接触线应在针阀锥面的大端部位。其作用是补偿表面粗糙度的不规则和同心度的偏差。这个夹角差慢的大小与喷油时的跳动响声有很大关系。座面密封不好，表现为渗漏或滴漏，结果导致燃烧恶化，增加积炭，甚至产生不规则的敲击声，工作不均匀和排气冒烟。是什么意思？

The seat surface angle of the needle valve seat 58 030 and the needle valve cone angle of 600 (with a few 900). Such small differences in the angle between the needle and the needle valve seat surface contact to line contact, the contact line should be in the big end of the needle valve cone parts.