Pitch-change mechanism with locking device

A pitch-change mechanism for adjusting an angular position of at least one variable-setting blade of an aircraft turbomachine around a pivot axis of the variable-setting blade, said pitch-change mechanism comprising:

• a frame fixed relative to the pivot axis,
• a control actuator including a fixed part integral with the frame and a moving part,
• a connecting system connecting the moving part to the variable-setting blade so as to convert movement of the moving part relative to the fixed part into a rotation of the variable-setting blade around the pivot axis, and
• a pitch locking device suitable for blocking the movement of the moving part relative to the fixed part in at least one direction,
• wherein the pitch locking device comprises:
• a blocking surface integral with the frame or movable jointly with the moving part relative to the frame,
• a guide surface facing the blocking surface and comprising a surface portion at a fixed first distance from the blocking surface,
• a blocking member interposed between the blocking surface and the guide surface and having a guide face facing the guide surface, said blocking member having an unlocking configuration spaced from the blocking surface, in which a face portion of the guide face is at a second distance from the blocking surface, greater than the first distance, and a locking configuration engaged with the blocking surface so that the moving part is immobilized relative to the frame, in which the face portion is at the first distance from the blocking surface,
• the guide surface and the blocking member being movable relative to each other parallel to the blocking surface between a first configuration, in which the surface portion is spaced from the face portion, and a second configuration in which the face portion bears against the surface portion,
• the pitch locking device further comprising:
• a biasing member which exerts an urge on the guide surface or the blocking member toward the second configuration, and
• a holding device for holding the guide surface and the blocking member in the first configuration under certain predetermined conditions.
• wherein the guide surface converges toward the blocking surface so that, when the guide surface and the blocking member are in the second configuration, the force of the biasing device on the guide surface or the blocking member is converted into a force of pressing the blocking member on the blocking surface by wedge effect, this creating an adhesion force at the interface between the blocking member and the blocking surface, the biasing device being dimensioned so that said adhesion force blocks any movement of the blocking surface relative to the blocking member.