Combined variable angle stator and windmill control system

Claim 2

In a turbojet engine having a row of variable compressor stator vanes, a combined variable angle stator and windmill brake control system comprises: a driving member connected to a row of variable stator vanes for adjusting the angle of the vanes; a first link member, one end of which connects to the driving member; a differential bellcrank, one end of which rotatably connects to the other end of the first link member; a windmill brake actuating means connecting the differential bellcrank at a point intermediate the ends thereof, so as to provide a point about which the differential bellcrank may pivot for variation of the angle of the stator vanes during normal engine operation; a variable stator actuating means connecting the other end of the differential bellcrank to provide rotation of the differential bellcrank about the pivot point thereby moving both the first link member and driving member in order to vary the angle of the stator vanes, wherein actuation of the windmill brake means operates to move the differential bellcrank from its pivot point and drive the variable stator vanes into the closed position so as to block the flow therethrough and brake engine windmilling.

Claim 3

The combined variable angle stator and windmill brake control system of claim 1 including at least two longitudinally spaced rows of variable stator vanes, each connected to a respective driving member and moved by the variable stator actuating means wherein one of the rows of variable stator vanes is adjusted through movement of the differential bellcrank and first link member and actuation of the windmill brake actuator means operates to close off only that row of variable stator vanes adjusted through the differential bell-crank and first arm.

Claim 4

The combined variable angle stator and windmill brake control system of claim 2 including: a guide in fixed connection to the turbojet engine and having a track therein for receipt of a roller, rotatably fixed to that end of the differential bellcrank which connects to the variable stator actuating means wherein the track includes adjustable means therein for limiting the distance travelled by the roller within the track.

Claim 5

The combined variable angle stator and windmill brake control system of claim 2 wherein the variable stator actuating means includes: a torque tube rotatably connected to the engine casing; a second link member conneCting between a point on the torque tube radially outward from the center axis thereof and a point at the other end of the differential bellcrank such that rotation of the torque tube imparts substantially linear motion to the second link in turn rotating the differential bellcrank about the pivot point to adjust the angle of one row of variable stator vanes; third link members connecting other points on the torque tube radially outward from the center axis thereof to respective driving members such that rotation of the torque tube imparts substantially linear motion to the third links, in turn moving the respective driving members so as to adjust the other variable angle stator vanes; and an actuator connected to the engine casing and including an output member connecting to a point on the torque tube radially outward from the center axis thereof, such that linear movement of the output member operates to rotate the torque tube.

Claim 6

The combined variable angle stator and windmill brake control system of claim 2 including: a torque tube rotatably connected to the engine casing and including a plurality of spaced apart crank arms extending radially outward from the surface thereof; a stop member in fixed connection to the engine casing for limiting rotation of the torque tube; a second link member connecting a crank arm to the other end of the differential bellcrank such that rotation of the torque tube imparts substantially linear motion to the second link in turn rotating the differential bellcrank about the pivot point to adjust the angle of the aft most row of variable stator vanes; third link members connecting the other crank arms to respective driving members such that rotation of the torque tube imparts substantially linear motion to the third links, in turn moving the respective driving members so as to adjust the variable angle stator vanes; the variable stator actuator means connected to the engine casing and having an output member connecting to a crank arm from the torque tube such that linear movement of the output member operates to rotate the crank arm and torque tube; and the windmill brake actuator means connected to the engine casing and having a second output member connecting to a point intermediate the ends of the differential bellcrank wherein actuation of the windmill brake means operates initially to linearly move the windmill brake output member, differential bellcrank, and second link member so as to rotate the torque tube against the stop member and open the stator vanes, and wherein continued movement of the windmill brake output member then operates to rotate the differential bellcrank about the point of connection to the second link member and move the first link member and its associated driving member to close off the aft most row of variable stator vanes.