Nittan Valve Co., Ltd.

Osamu Tsuneishi

Masaaki Inoue

Naoya Ishihara

Atsuyuki Ichimiya

A hollow poppet valve () having an improved heat transfer capability is provided. The valve has an internal cavity (S), extending from within a valve head () into a stem () of the valve, is loaded with a coolant () together with an inert gas. The coolant in the valve head () is stirred by swirl flows of the coolant generated during reciprocal motions of the valve. A multiplicity of swirl-forming protrusions are formed on at least on one of the bottom and the ceiling of the valve head cavity (S) in such a way that swirl flows (F, F) of coolant are generated by the protrusions in the valve head cavity (S) during reciprocal motions of the valve to thereby stir the coolant in the circumferential direction of the cavity (S).

Hollow poppet valve

With a poppet valve using a coolant, maximum combustion efficiency is realized by adjusting relative values of a heat insulation effect and a heat dissipation effect. From the inside of a head portion () to a stem portion () of a hollow poppet valve () a heat insulating space (S) and a cooling portion (S) loaded with a coolant (), separated from each other by a partition (), are formed. By properly setting an installation position and a vertical length of the partition () according to a type of vehicle for which the valve is used, appropriate heat insulation effect and heat dissipation effect are obtained. Further, by the partition (), mechanical or thermal strength of the poppet valve in which the heat insulating space (S) and the cooling portion (S) are formed is increased.

A hollow poppet valve () has an internal cavity (S) which comprises a diametrically large valve head cavity (S) formed in a valve head () and a diametrically small stem cavity (S) formed in a stem () in communication with the valve head cavity (S). The stem cavity has a diametrically larger first portion (S) near the end of the stem and a diametrically smaller second portion (S) near the valve head. A step () is formed at the boundary of the first and the second portion of the stem cavity (S). The internal cavity is loaded with a coolant to a level above the step, together with an inert gas. In response to a reciprocal motion of the valve, turbulent flows of coolant (F) are created in the neighborhood of the step (), facilitating active stirring of the coolant () in the cavity (S).

Growing community of inventors

Kanagawa, Japan

Osamu Tsuneishi