Hollow poppet valve

A hollow poppet valve having a stem integral at one end thereof with a valve head, the valve having an internal cavity that extends from within the valve head into the stem and charged with a coolant together with an inert gas, the poppet valve comprising:

• the valve head having therein an internal valve head cavity having a truncated-cone shape peripheral wall with a conic surface substantially in parallel with a tapered outer periphery of the valve head;
• the stem having therein a linear internal stem cavity connected at an interconnecting opening to an upper end of the internal valve head cavity, said internal stem cavity having a peripheral wall that extends to said interconnecting opening that is substantially parallel to a longitudinal axis of the stem;
• and
• said internal valve head cavity having a planar ceiling surface that extends to said interconnecting opening and that is substantially perpendicular to said longitudinal axis of the stem, such that said planar ceiling surface of said internal valve head cavity and said peripheral wall of said internal stem cavity intersect at the interconnecting opening and form a substantially perpendicular annular step;
• whereby a vertical convective flow of coolant along the longitudinal axis of the valve is established at least in the internal valve head cavity during a reciprocal motion of the valve.