| 摘要 |
<p>A shear-type, fail-fixed servovalve is disclosed which includes a piston whose piston head is movably disposed in one chamber of a multi-chamber housing. A piston rod is attached to the piston head and extends into the other chambers. Two passages extend through the piston rod and communicate with the chamber on opposite sides of the piston head. A pair of input orifices are located proximate each other at one end of the piston rod, each corresponding to one passage. An angularly movable jet pipe emits fluid directed at the input orifices. The jet pipe has a null angular position disposed at a predetermined offset angle with respect to the axis of the piston rod, and directs fluid towards the pair of orifices. Means responsive to a selectively variable control signal for changing the angular position of the jet pipe is provided which is effective to produce a magnified linear piston displacement by varying the relative amounts of fluid supplied to the input orifices. Shoes supported by the piston rod slide over ports in a plate surface in another chamber and the ports are opened and closed in accordance with the linear position of the piston. The opening and closing of these ports, in turn, determines the linear displacement of a separate servopiston. A method of operating a two-stage servovalve is disclosed which includes the step of changing the angular position of the jet pipe and producing magnified linear position displacement thereby.</p> |
