| 摘要 |
PURPOSE:To carry out a multistage control of a flow rate using a small number of switching valves by providing in parallel (n) changeover flowpaths having different passing flow rates at the intermediate of a flowpath and also providing driving means for selectively opening or closing respective switching valves provided in these changeover flowpaths, thereby to control the flow rate in 2<n> stage. CONSTITUTION:The flow rate of an adjusting valve 12a opened or closed by a valve stem 16 a is set at a relatively small value, and the flow rate of an adjusting valve 12b opened or closed by a valve stem 16b is set to a value larger than the flow rate of the adjusting valve 12a by a predetermined value. Further, the flow rate of an adjusting valve 12c opened or closed by a valve stem 16c is set a valve larger than the flow rate of the adjusting valve 12b by a predetermined valve. Thus, at the rotational position of an initial rotational shaft 20, an minimum amount of a gas fuel is supplied to a gas burner 1 by passing the gas fuel only through the adjusting valve 13 of a minimum gas flow path 13, and the rotational shaft 20 is controlled of its rotation at desired angle clockwisely. A cam plate 21 is arranged with valve stems 16a, 16b and 16c coaxially with respect to the rotational shaft 20 and having different diameters, and the valve stems 16a, 16b and 16c are combined to integrally from projections 22a, 22a, 22b, 22b and 22c. By this organization, the flow rate of the gas reaching a gas nozzle 3 can be adjusted in 2<n> stages and miniaturization of the valve main body can be carried out. |
