| 摘要 |
A valve that controls the delivery of a fuel gas through a delivery duct 3 includes a valve seat 6 in the duct, a closure member 5 associated with the seat, and a motor-driven actuator 7 that acts on the closure member in order to open/close the valve seat. The valve unit also includes an electromagnetic unit 22 with a first portion 23 carrying a magnetizing winding 24 and a second portion 25 which can be fixed firmly to the first portion by magnetization. The electromagnetic unit 22 is associated with the actuator in order to act on the closure member 5 so as to close the valve seat 6, irrespective of the operative position of the actuator 7, upon the occurrence of a predetermined condition which requires the valve seat to be shut off, and the actuator means 7 is movable, together with the second portion 25 of the electromagnetic unit, during the movement to control the closure member 5 so as to open/close the valve seat, the first portion 23 of the electromagnetic unit being connected to a stationary structure of the valve unit.
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