Respiration apparatus with flow responsive control valve

Claim 2

In a respiration apparatus for administering intermittent positive pressure breathing therapy to a patient, and having delivery means for administering gas to the patient, and conduit means for carrying the gas from a source to the delivery means, the combination of: a control valve having a flow passage with an inlet end for receiving gas from the source at a regulated, substantially constant input pressure, an outlet end, a tubular valve seat member adjustably mounted in said valve, said seat member having a beveled annular end along one side of said passage and terminating in an annular seat projecting varying distances into said passage in different adjusted positions of said seat member, the interior of said seat member communicating between said outlet end and said conduit means, and a plunger slidably mounted in said valve for movement toward and away from said seat, between open and closed positions; a piston carrying said plunger and slidably mounted in said valve, said valve having first and second pressure chambers on opposite sides of said piston, said first chamber communicating with said inlet end and arranged to apply force to said piston determined by inlet pressure, thereby to urge said plunger toward said open position; spring means urging said plunger toward said closed position with a preselected force; first and second signal conduits communicating respectively with said outlet end and with said second chamber, to apply the pressure in said outlet end to said second chamber when said signal conduits are connected, thereby urging said plunger toward said closed position; pilot valve means normally connecting said signal conduits and operable when actuated to vent said second chamber through said second signal conduit, thereby to permit the force of inlet pressure in said first chamber to shift said plunger to the open position; means communicating with said conduit means, responsive to a slight inspiratory effort at said delivery means and operable to actuate said pilot valve means momentarily, thereby initiating a flow of gas through said control valve; and means responsive to back pressure in said conduit means for restricting the flow rate as such back pressure increases during inflation of the patient, thereby reducing the flow rate past said plunger and causing the latter to move toward said seat and close against the latter when a preselected terminal flow, determined by the adjustment of said seat, is achieved, such closure terminating the delivery of gas from the source to said conduit means.

Claim 3

In a respiration apparatus for administering intermittent positive pressure breathing therapy to a patient, and having delivery means for administering gas to the patient, and conduit means for carrying the gas from a source to the delivery means, the combination of: a control valve having a flow passage with an inlet end for connection to the source and an outlet end connected to said conduit means to deliver gas thereto, a valve seat, and a valve member movable back and forth, toward and away from said seat between an open position and a closed position and operable to admit a peak flow from the source through said passage in said open position, to block flow from the source through said passage to said conduit means in said closed position, and to variably restrict said passage in intermediate positions; pressure-responsive means for positioning said valve member in said passage in accordance with the flow rate to said delivery means and maintaining a substantially constant pressure drop across said valve member and between said inlet and outlet ends while gas is flowing through said passage, said pressure-responsive means including first means urging said valve member toward said open position with a first force determined by the pressure at said inlet end, second means urging said valve member toward said closed position with a second force determined by the pressure at said outlet end, and spring means for adding a preselected third force to said second force and variably positioning said valve member in said passage to maintain a preselected pressure drop across the valve member while gas is flowing through said passage, and normally holding said valve member in said closed position to prevent flow through said passage; means actuated by an inspiratory effort of the patient at said delivery means for momentarily shifting said valve member out of the closed position to start flow to said conduit and delivery means at a selected peak flow rate; and rate-control means in said conduit means responsive to the back pressure in said apparatus during inflation of the patient, and operable to restrict the flow rate as the back pressure builds up, whereby increasing back pressure results in a decreasing flow rate and a tendency to reduce said pressure drop, and said pressure-responsive means shifts said valve member toward said seat to maintain said pressure drop until said valve member engages said seat to terminate the flow, said seat being disposed along one side of said flow passage in a preselected position determined by the position of said valve member when the desired terminal flow rate occurs.

Claim 4

In a respiration apparatus for administering intermittent positive pressure breathing therapy to a patient, and having delivery means for administering gas to the patient, and conduit means for carrying the gas from a source to the delivery means, the combination of: a control valve having a flow passage with an inlet end for connection to the source and an outlet end connected to said conduit means to deliver gas thereto, a valve seat, and a valve member movable back and forth, toward and away from said seat between an open position and a closed position and operable to admit a peak flow from the source through said passage in said open position, to block flow from the source through said passage to said conduit means in said closed position, and to variably restrict said passage in intermediate positions; pressure-responsive means for positioning said valve member in said passage in accordance with the flow rate to said delivery means and maintaining a substantially constant pressure drop across said valve member and between said inlet and outlet ends while gas is flowing through said passage, said pressure-responsive means including first means urging said valve member toward said open position with a first force determined by the pressure at said inlet end, second means urging said valve member toward said closed position with a second force determined by the pressure at said outlet end, and spring means for adding a preselected third force to said second force and variably positioning said valve member in said passage to maintain a preselected pressure drop across the valve member while gas is flowing through said passage, and normally holding said valve member in said closed position to prevent flow through said passage; means actuated by an inspiratory effort of the patient at said delivery means for momentarily shifting said valve member out of the closed position to start flow to said conduit and delivery means at a selected peak flow rate; and rate-control means in said conduit means responsive to the back pressure in said apparatus during inflation of the patient, and operable to restrict the flow rate as the back pressure builds up, whereby increasing back pressure results in a decreasing flow rate and a tendency to reduce said pressure drop, and said pressure-responsive means shifts said valve member toward said seat to maintain said pressure drop until said valve member engages said seat to terminate the flow, said seat being disposed along one side of said flow passage in a preselected position determined by the position of said valve member when the desired terminal flow rate occurs.

Claim 5

Respiration apparatus as defined in claim 2 further including means mounting said seat for selective adjustment across said passage, toward and away from the open position of said valve member, thereby to vary the flow rate at which said valve member engages said seat.

Claim 6

Respiration apparatus as defined in claim 3 in which said seat is the annular end of a tubular member, and in which the interior of said tubular member connects said passage to said conduit means and is blocked by engagement of said valve member with said end.

Claim 7

Respiration apparatus as defined in claim 4 in which said tubular member has a peripherally beveled end forming said seat.

Claim 8

Respiration apparatus as defined in claim 2 in which said pressure-responsive means comprise a piston connected to said valve member, a first chamber on one side of said piston communicating with said inlet end to form said first means, and a second chamber on the other side of said chamber connected for communication with said outlet end to form said second means.

Claim 9

Respiration apparatus as defined in claim 6 in which said means for momentarily shifting said valve member out of said closed position comprise a pressure-operated pilot valve operable when actuated, in response to patient suction, to vent said second chamber.