PURPOSE: To control an amount of air to be supplied to an air passage, restrict an occurrence of yellow flame within a combustion chamber and restrict a leakage of unburnt gas from the combustion chamber into the air passage and to prevent a deterioration of combustion characteristic under a weak combustion by a method wherein a small diameter part is formed at an upper part of an outer cylinder.
CONSTITUTION: Since a small diameter part 14 is made to have a desired height area, an amount of supplying air to be supplied to an air passage 19 through a small diameter part 14 of an outer cylinder 13 is controlled and at the same time its flow is restricted. Its flow is directed upward along a wall surface of a red heated part 11 as indicated by a white arrow A and mainly supplied from an upper part of the red heated part 11 to a combustion chamber 8. Therefore, air supplied from the lower part of the red heated part 11 to the combustion chamber 8 is relatively low in its volume, flame formed within the combustion chamber 8 is covered by an air layer and so no yellow flame is generated. Even in the case that an exposed height of a wick 1 is lowered and an amount of combustion is reduced to a lower value to cause the flame to be dropped into the combustion chamber 8 to show a state of (fs), an amount of unburnt gas discharged from a through-pass hole 12 above the flame (fs) into the surrounding atmosphere decreases and thus it is possible to prevent a deterioration of a combustion characteristic.
ISHIKAWA KATSUHIKO
INOUE SHOJIRO
