| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To freeze the position of an actuator in the event of an electrical failure without a substantial risk of drift. <P>SOLUTION: In the event of an electrical control failure, the slide of a distributor 20 is taken to a safety position in which control chambers 62, 64 of the actuator 50 are at the same low or high pressure opposed to that applied in an intermediate chamber 66 so that each stage of the actuator slide is subjected to high pressure on one side and to low pressure on the other side. Sealing between each of stages 54, 56 of the actuator slide and an actuator cylinder 60 is carried out by a dynamic seal 70 producing a frictional force between the stage and cylinder, depending on the difference between the pressures exerted on the two sides of the stage so that, in the event of the electrical control failure, the actuator slide valve is immobilized in its position at the moment of the failure ("fail freeze"). <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
