Vent and aav arrangement for patient interface

A patient interface to deliver a flow of air at a positive pressure with respect to ambient air pressure to an entrance to the patient's airways including at least the entrance of a patient's nares while the patient is sleeping, to ameliorate sleep disordered breathing, the patient interface comprising:

• a seal-forming structure constructed and arranged to form a seal with a region of a patient's face surrounding the entrance to the patient's airways, the seal-forming structure forming at least a portion of a plenum chamber pressurizable to a therapeutic pressure;
• and
• a vent and AAV arrangement configured to regulate flow therethrough to (1) provide a vent flow path when pressure in the plenum chamber is above a predetermined magnitude and (2) provide a breathable flow path when pressure in the plenum chamber is below the predetermined magnitude or not delivered,
• the vent and AAV arrangement comprising:
• a shell portion including a port extending therethrough, the port configured to allow gas to flow between the plenum chamber and ambient;
• an AAV member provided to the shell portion, the AAV member including a flap portion structured and arranged to regulate flow through the port,
• wherein the flap portion includes a plurality of vent holes therethrough,
• wherein the flap portion is movable to a deactivated position when pressure in the plenum chamber is above the predetermined magnitude to cover the port so that a vent flow of gas is allowed to pass along the vent flow path that extends through the plurality of vent holes of the flap portion and through the port, and
• wherein the flap portion is movable to an activated position when pressure in the plenum chamber is below the predetermined magnitude or not delivered to uncover the port so that a breathable flow of gas is allowed to pass along the breathable flow path that extends through the port;
• a diffusing member provided to the shell portion, the diffusing member configured and arranged such that the port is covered by the diffusing member so that at least a portion of the vent flow of gas passes into the diffusing member;
• and
• a diffusing member cover to retain the diffusing member to the shell portion, the diffusing member cover including an anterior wall completely covering an anterior side of the diffusing member,
• wherein the diffusing member and diffusing member cover are supported in spaced relation from an outlet end of the port to form a lateral opening between the shell portion and the diffusing member and diffusing member cover, and
• wherein at least a portion of the vent flow of gas passes into the diffusing member along the vent flow path and then is redirected laterally by the anterior wall to flow through the lateral opening to ambient.