| 摘要 |
<p>PROBLEM TO BE SOLVED: To extinguish a burner with good responsiveness on the occurrence of abnormal conditions, in a premixing device with air resistance switching means for switching ventilation resistance of an air supply passage to the magnitude and gas resistance switching means for switching ventilation resistance of a gas feeding passage to the magnitude.SOLUTION: A resistance switching valve V constituting air resistance switching means and gas resistance switching means has a cylindrical valve body 6. When the valve body 6 is present in an open position, an air inlet path 61, a gas inlet path 62 and an outflow path 63 are brought into communication with an air supply path 3, a gas supply path 4 and a fuel/air mixture passage 5, respectively. By turning the valve body 6 in the open position, communication opening degrees to the air supply path 3 and the gas supply path 4 are changed to the magnitude, respectively. Also, when the valve body 6 is present in a closed position, the communication of the air inlet path 61, the gas inlet path 62 and the outflow path 63 with the air supply path 3, the gas supply path 4 and the fuel/air mixture passage 5 are cut, respectively.</p> |
