| 摘要 |
<p>A valve unit for regulating the flow-rate of a fuel gas delivered through a delivery duct (3) is described and comprises a servo-valve (4) having a closure element (5) controlled by a diaphragm (8), the diaphragm being subjected to the gas-delivery pressure on one side and to a reference pressure established in a control chamber (9) of the servo-valve on the other side, a pressure-regulator device associated with the servo-valve (4) and comprising a regulation valve (10; 51) for controlling the reference pressure in the control chamber (9), additional regulator means for modulating the delivery pressure and/or the output flow-rate of gas through the delivery duct (3) in dependence on an external control, the additional regulator means acting alternatively on the pressure-regulator device or on means (53) for choking the delivery duct in order to modulate the delivery pressure, or to modulate the flow-rate delivered through the delivery duct (3), respectively, and actuator means for the additional regulator means, comprising a reversible motor (32) having a rotor (31) connected to a male-and-female screw coupling (28, 29; 58, 57) acting on the pressure-regulator device or on the choking means, for the operative control thereof. <IMAGE></p> |
