Purely rotational casement window

A window casing comprising:

• a fixed frame comprising a first jamb and a second jamb;
• a movable hung sash pivotally connected to said fixed frame by means of hinges which define at said first jamb a rotation axis (X) of the hung sash with respect to the frame, said second jamb running along a longitudinal axis (X′) parallel with said rotation axis (X);
• means for locking or unlocking the hung sash with respect to the frame, slidable according to said longitudinal axis (X′) on the frame between a first position, or locking position, at which said locking or unlocking means engage with the hung sash to prevent the opening thereof, and a second position, or unlocking position, at which said locking or unlocking means disengage from the hung sash to allow the opening thereof;
• a handle mounted on the frame and operatively connected to the locking or unlocking means;
• at least one arm arranged between the second jamb and the hung sash, adapted to move between a closing configuration substantially parallel to said longitudinal axis (X′) and an opening configuration substantially crosswise with said longitudinal axis (X′);
• for each arm, opening or closing means adapted to drive the arm between said opening configuration and said closing configuration, this implying the consequent opening or closing of the hung sash with respect to the frame;
• said locking or unlocking means being further operatively connected to said opening and closing means so as to control the actuation of the arm following a sliding beyond said unlocking position;
• said opening or closing means comprising a fixed element integral with said frame and a movable element integral with said locking or unlocking means, adapted to translate with respect to said fixed element along said longitudinal axis (X′);
• a first end of the arm being pivotally engaged in a constraint on said fixed element, as well as pivotally and slidably engaged with a slot on said movable element;
• said slot having a longitudinal segment parallel to the longitudinal axis (X′) and at least one crosswise segment diverging from said longitudinal axis (X′);
• wherein additionally said slot and said constraint on said fixed element are misaligned both in the direction of said longitudinal axis (X′) and in the direction transversal thereto, thus to a first rotation of said handle and an ensuing first translation of said locking or unlocking means up to said unlocking position, the arm is kept engaged with said longitudinal segment of said slot in configuration parallel to the longitudinal axis (X′), while at a second rotation of said handle and an ensuing second translation of said locking and unlocking means beyond said unlocking position, the arm is pushed towards said opening configuration for a controlled opening of said hung sash due to the slidable engagement with said at least one crosswise segment of the slot, and vice versa;
• and
• said constraint on said fixed element providing a spheroidal peripheral surface on which the arm is engaged thereto in a ball joint arrangement.