| 摘要 |
<p>A cylinder for delivering at limited positive pressure a preselected limited volume of breathing gas at a preselected limited flow rate. The cylinder includes a cylindrical housing which is substantially closed to the atmosphere. A drive weight is movably mounted within the cylinder, with a rolling diaphragm being connected between the wall of the cylinder and the weight to divide the cylinder into upper and lower chambers. A vacuum source is connected to the upper chamber to draw the weight and diaphragm upwardly, expanding and drawing breathing gas into the lower chamber. By controllably releasing the vacuum in the upper chamber, the weight is allowed to fall downwardly, solely under the force of gravity, to cause the lower chamber to contract. This creates a positive pressure in the lower chamber, forcing the breathing gas out of an outlet for delivery to a patient. The weight is slidably mounted on a hollow tube which extends axially through the housing, and a follower chain connected to the weight passes through the tube to an external indicator. The tube may be slotted to accomodate a connection between the follower and the weight to provide a positive indication of the exact location of the weight, and a bellows arrangement is provided to seal the upper and lower chambers from the area occupied by the tube.</p> |
