Thrust reverser with adjustable section nozzle for aircraft jet engine

Thrust reverser for a bypass aircraft jet engine, mounted in an outer cowling surrounding an engine structure and having the same longitudinal axis thereas, said cowling defining with the engine structure an annular duct through which a stream of gas pushed by a fan can flow from an upstream region towards a downstream region of the cowling, said reverser consisting of pivoting doors arranged in openings made in said cowling and defined, upstream and downstream, by upstream and downstream annular fixed parts of the cowling and, laterally, by longitudinal beams integral with the cowling, said doors being articulated, in a fixed structure consisting of the fixed parts of the cowling, about pivots so that they can be moved, under the action of a command to pivot, between a stowed position in which the doors close off the openings in the cowling, and a deployed position in which the doors block the flow of the stream of gas flowing in the annular duct in order to deflect it outwards to create reverse thrust, wherein a translating annular nozzle, capable of sliding longitudinally, parallel to the axis of the engine, between an upstream position and a downstream position, is housed inside the downstream annular fixed part of the cowling, an upstream end of the nozzle having an immobilizing means which, when the nozzle is in the upstream position, can immobilize the pivoting doors in the stowed position, thus preventing any inadvertent deployment of the doors and which, when the nozzle is in the downstream position, ceases to immobilize the doors, thus allowing them to be pivoted from their stowed position to their deployed position.