Vacuum suspended type servo-motor

Claim 1

A vacuum-suspended type servo-motor comprising: a casing; a movable wall arranged in said casing to divide the interior space thereof into two compartments, including a first power chamber continuously communicating with a source of vacuum and a second power chamber normally communicating with said first power chamber, said movable wall being displaceable by pressure difference between said first and second power chambers; an input member slidably fitted in said movable wall; an output member; reaction means operably connecting said output member with said input member and said movable wall; and control valve means normally holding said second power chamber in communication with said first power chamber and operable upon forward movement of said input member to close off the communication between said first and second power chambers and subsequently to place said second power chamber in communication with the external atmosphere; said reaction means including rocker levers each extending between said input member and said movable wall and held intermediate the ends thereof in engagement with said output member whereby, when said output member is loaded by forward movement of said input member, the load reaction is partially transmitted to said input member through said rocker levers, said control valve means being provided with a valve chamber within said input member and communicating with the external atmosphere, a first valve port formed in said input member and communicating with said valve chamber and said second power chamber, said control valve means comprising a communicating tube having opposite ends, a plurality of support arms radially extending from one end of said communicating tube to mount said tube on said movable wall, said tube being slidably fitted in said input member axially thereof, said communicating tube defining at the other end thereof a second valve port which opens coaxially with said first valve port, said tube communicating at said one end with said first power chamber, and a valve element accommodated in said valve chamber and normally biased toward said first and second valve ports; said output Member including an output transmitting flange at the rear end thereof for engagement with said rocker levers intermediate the ends thereof, said rocker levers being each rockably arranged between two adjacent support arms of said communicating tube which prevent circumferential displacement and between said communicating tube and a projection formed on the front side of said movable wall which prevent radial displacement.