Backpressure modulating cartridge for a respiratory mask

摘要

The cartridge has a body (2) which fits onto a respirator mask (6) and connects with the ambient medium via exhalation (13) and inhalation (22) valves. The body has two chambers (8,9) linked by a passage (10) which has a guide rod passing through it. One of the chambers is connected to the respirator mask and the other to the ambient atmosphere. The guide rod carries the mobile exhalation valve (13) with apertures (21), and the mobile inhalation valve which fits inside the passage and covers the apertures. Both valves are held under tension by coaxial spiral springs (14,23) on the guide rod which are held between the valves and stops (4,15). The guide rod is located concentrically in the housing, which has an inner annular rim defining the passage and acting as a stop for the exhalation valve.