| 摘要 |
A solenoid valve for an irrigation control unit comprises a cut-off element movable inside a respective seat between a closed position and an open position. The cut-off element defines inside the seat a chamber in constant communication with the inlet of the solenoid valve, so that the pressure exerted on the cut-off element by the water present at the inlet of the solenoid valve is balanced by the pressure exerted on the cut-off element by the water present in the chamber. The cut-off element is provided with a passing conduit that can be opened so that the chamber can be put in communication with the outlet of the solenoid valve. Since the pressure exerted on the cut-off element by the water present at the inlet of the solenoid valve is no longer balanced by the pressure exerted on the cut-off element by the water present in the chamber, the cut-off element is displaced by the thrust of the water present at the inlet of the solenoid valve in said open position. The solenoid valve also comprises a bistable electromagnetic device comprising an electromagnetically-operated valve suitable for determining alternatively the closing and the opening of said passing conduit as a result of the generation of an electrical control impulse and up to the generation of an opposite electrical impulse.
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