| 摘要 |
<p>PURPOSE:To exercise proportional control over a flow rate of gas smoothly by a proportional gas control system which changes ranges of control current according to the kind of gas, by varying the control current for a solenoid from starting current to maximum energizing current while keeping the diameter of a valve constant. CONSTITUTION:To temperature setting part 11, temperature detection part 12, linear amplification part 13, control part 14, drive output part 15, feedback signal circuit 16, and proportional control valve 17, starting current setting part 18 and maximum energizing current setting part 19 are added. Then, setting part 18 applies a DC bias to a signal system as shown in fig. M to prevent the current flowing through valve 17 from decreasing below the starting current even if the signal level reaches ''0''. To setting part 19, a means of cutting the current at the level, equivalent to the maximum energizing current of a control signal level, for example, by a clipping circuit using a Zener diode is applicable. Then, while the diameter of a gas valve is kept constant, the control current for the solenoid is varied from the starting current to the maximum energizing current to exercise the proportional control over a flow rate of gas smoothly without reference to the kind of the gas.</p> |
