| 摘要 |
PURPOSE:To securely prevent a solenoid valve from opening even at the time of failure such as the metallic deposition, etc. of a relay contact and increase safety by connecting two relay contacts, which are closed by means of relay drive circuits respectively, and an exciting coil of said solenoid valve, in series to a power source. CONSTITUTION:A solenoid-valve circuit which is formed by connecting a first and a second relay contact 2, 3 to the exciting coil 4 of a solenoid valve in series, is connected to a power source 1. Each of the relay contacts 2, 3 are controlled for opening and closing by a first and a second relay drive circuit 5, 10 respectively, which are series circuits consisting of transistors 8, 13, to which resistors 6, 7 and 11, 12 are connected on the base sides, and first and second relay exciting coils 9, 14, respectively. The relay drive circuit 5, 10 are controlled for driving by means of a microcomputer 15, as a relay driving signal generating means, and a starting signal, which is generated when a water tap, etc. is turned on, and each monitor signal for a connecting point A between the both contacts 2, 3, and for a connecting point B between the contact 3 and the exciting coil 4, are inputted in this microcomputer 15. |
