Patent ID: 7779860

Claim:
An airflow control mechanism comprising: a conduit for air having an inlet located at a first end thereof and an outlet located at a second end thereof; a first opening formed in a side of said conduit and able to provide a secondary inlet thereto; a movable collar at least partially surrounding said conduit at a location alignable with said first opening, such that said collar is able to at least partially occlude said first opening; characterized by: a second opening beside the first opening as part of the secondary inlet, wherein the collar is also alignable with said second opening, such that said collar is able to at least partially occlude said second opening at the same time as said first opening; and wherein the collar is provided with a plurality of channels ending in a window, each channel alignable with a corresponding one of said openings of the secondary inlet, said channels having a scalloped shape and extending in a direction parallel to an axis of said collar to appropriately guide air smoothly into said openings.