초록 ▼

The present invention provides an actuator controlled by an electro-hydraulic servovalve with a failfixed operation upon the loss of electrical power to the servovalve. A lock valve has apertures therethrough with friction pads therein for locking the actuator in position upon loss of the electrical

The present invention provides an actuator controlled by an electro-hydraulic servovalve with a failfixed operation upon the loss of electrical power to the servovalve. A lock valve has apertures therethrough with friction pads therein for locking the actuator in position upon loss of the electrical power.

대표청구항 ▼

[ I claim:] [1.] In an actuator for positioning a device having a piston movable in a bore and an electrohydraulic servovalve for controlling a first pressure signal to a first end of the piston and a second pressure signal to a second end of the piston to move the piston in response to an electrica

[ I claim:] [1.] In an actuator for positioning a device having a piston movable in a bore and an electrohydraulic servovalve for controlling a first pressure signal to a first end of the piston and a second pressure signal to a second end of the piston to move the piston in response to an electrical signal, an improved failfixed valve for maintaining the piston in a fixed position upon failure of the electrical signal comprising:sleeve means disposed in close fitting relation around a portion of the piston, said sleeve means having an aperture means therethrough disposed circumferentially thereabout;friction pad means adapted to be received in said aperture means, said friction pad means radially movable in said aperture means;a flexible sleeve means surrounding a portion of said sleeve means, said flexible sleeve means disposed in close fitting relation with said friction pad means; andvalve means in fluid communication with the first and the second end of the piston for receiving the first and the second pressure signals, said valve means operative upon failure of the electrical signal to supply a locking pressure to said flexible sleeve means whereby said flexible sleeve means transmits said locking pressure to said friction pad means to force said friction pad means against the piston such that said friction pad means and said sleeve means move with the piston and such that said valve means controls the first and the second pressure signals in response to movement of said friction pad means and said sleeve means so that the piston is clamped in a fixed position.