Seal-forming structure, positioning and stabilizing structure and diffuser vent 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 frame assembly;
• and
• a cushion assembly configured to removably and repeatably connect to the frame assembly,
• wherein the frame assembly and the cushion assembly form at least part of a plenum chamber pressurizable to a therapeutic pressure,
• wherein the cushion assembly comprises a one-piece construction including 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 and a frame connection structure constructed and arranged to removably and repeatably connect the cushion assembly to the frame assembly,
• wherein the seal-forming structure comprises a first elastomeric material and the frame connection structure comprise a second elastomeric material,
• wherein the first elastomeric material comprises a first Shore A durometer and the second elastomeric material comprises a second Shore A durometer,
• wherein the second Shore A durometer is higher than the first Shore A durometer,
• wherein the frame connection structure comprises an undercut that acts as an interface or catch adapted to connect to the frame assembly,
• wherein the frame connection structure is arranged along an interior surface or interior periphery of the seal-forming structure such that the frame connection structure and the undercut thereof is arranged or oriented towards an interior of the cushion assembly that forms at least a portion of the plenum chamber,
• wherein the cushion assembly further comprises a flexible sealing flap provided to the seal-forming structure and comprising the first elastomeric material,
• wherein the flexible sealing flap is configured and arranged to form a seal with the frame assembly when the cushion assembly is connected to the frame assembly,
• wherein the flexible sealing flap is arranged inward of the frame connection structure within the plenum chamber, and
• wherein the flexible sealing flap protrudes further from the interior periphery into the plenum chamber than the frame connection structure.