| 摘要 |
PURPOSE:To decrease the exhaust rate of nitrogen dioxide by keeping the temperature in combustion gas in a mixing space constant regardless of the combustion rate, by providing a valve mechanism which controls the open area of a secondary air feed hole in proportion to the combustion rate to a hot air heater. CONSTITUTION:In this valve mechanism, the pressure is applied on a part lower than a diaphragm 15 in a pressure chamber 13 when the feeding pressure of fuel by a pump 5 is high, so that the diaphragm 15 is pushed up against the tension of a spring 14, as well as to push up a valve 12. Accordingly the open area of an air feed hole 4 is increased, so that enough secondary air can be supplied. When the combustion rate is low, the pressure in the part lower than the diaphragm 15 in the pressure chamber 13 is decreased, so that the valve 12 is lowered in accompany with the descending diaphragm 15. By this operation the open area of an air feed hole 4 is decreased, and the rate of secondary air in accordance with the combustion rate is supplied from the secondary air feed hole 4. Accordingly the temperature in the secondary flames can be kept high and the concentration of NO2 in combustion gas can be suppressed low. |
