초록 ▼

A pneumatic oxygen conserving device for supplying oxygen to a user via a single-tube cannula is described. Inhalation is sensed by negative pressure in an output line 11 which causes a sensing valve 21 to open, thus venting a main control volume 14 via vent line 22. This fall in pressure causes a m

A pneumatic oxygen conserving device for supplying oxygen to a user via a single-tube cannula is described. Inhalation is sensed by negative pressure in an output line 11 which causes a sensing valve 21 to open, thus venting a main control volume 14 via vent line 22. This fall in pressure causes a main control valve 2 to open to supply a pulse of gas. This pressurizes the output line 11 which in turn causes the sensing valve 21 to close, thus preventing further venting. Volume 14 now re-pressurizes via line 15 and restrictor 16 and eventually reaches a level at which valve 2 closes and terminates the pulse of gas supplied to the user. A sensing delay valve 35 is incorporated in the vent line 22 from volume 14 to prevent the volume from venting after the first pulse has been delivered, until after the user has finished inhaling.

대표청구항 ▼

1. A pneumatically-controlled pneumatic conserving device for breathable gas, the device comprising: a pneumatically-controlled main control valve connected in a user supply line between an inlet for receiving a supply of breathable gas and an outlet for connection to a user,a main valve timer, comp

1. A pneumatically-controlled pneumatic conserving device for breathable gas, the device comprising: a pneumatically-controlled main control valve connected in a user supply line between an inlet for receiving a supply of breathable gas and an outlet for connection to a user,a main valve timer, comprising a main control volume, the pressure within the volume controlling the opening and closing of the main control valve, anda sensing valve for triggering the main valve timer to open the main control valve upon sensing inhalation by the user, and to deliver a pulse of gas of predetermined duration to the outlet,the device being characterised by a pneumatically-operated sensing valve inhibitor for inhibiting operation of the sensing valve, the inhibitor comprising:a sensing delay volume, the pressure within which controls operation of the inhibitor,a cylinder in which is situated a moveable member, the sensing delay volume being to one side of the moveable member;a delay line through which the sensing delay volume is pressurized by gas flow when the main control valve is open, anda delay timer comprising a flow restrictor and vent line connected to the sensing delay volume for controlling the sensing valve inhibitor to inhibit operation of the sensing valve for a predetermined period following the delivery of the pulse of gas to the outlet. 2. A conserving device as claimed in claim 1 wherein the delay line includes a one-way valve allowing flow into the sensing delay volume, but not in the reverse direction. 3. A conserving device as claimed in claim 2 further including a flow metering valve connected in the user supply line on the downstream side of the main control valve, and wherein the delay line is connected to the user supply line at a point between the main control valve and the flow metering valve. 4. A conserving device as claimed in claim 1 wherein the delay line is connected to the user supply line at a point downstream of the main control valve so as to enable the sensing delay volume to be pressurised from the user supply line. 5. A conserving device as claimed in claim 1 wherein the cylinder includes a biasing element for biasing the moveable member in a direction such as to reduce the capacity of the sensing delay volume. 6. A conserving device as claimed in claim 1 wherein the moveable member takes the form of a diaphragm. 7. A conserving device as claimed in claim 1 wherein the moveable member takes the form of a piston. 8. A conserving device as claimed in claim 1 wherein the vent line is arranged to vent the sensing delay volume to atmosphere. 9. A conserving device as claimed in claim 1 wherein the vent line is arranged to vent the sensing delay volume into the user supply line downstream of the main control valve. 10. A pneumatically-controlled pneumatic conserving device for breathable gas, the device comprising: a pneumatically-controlled main control valve connected in a user supply line between an inlet for receiving a supply of breathable gas and an outlet for connection to a user,a main valve timer, comprising a main control volume, the pressure within the volume controlling the opening and closing of the main control valve, anda sensing valve for triggering the main valve timer to open the main control valve upon sensing inhalation by the user, and to deliver a pulse of gas of predetermined duration to the outlet, the sensing valve being connected to the main control volume in such a way as to rapidly change the pressure in the volume in order to open the main control valve to supply gas to the user upon the sensing valve sensing inhalation by the userthe device being characterised by a pneumatically-operated sensing valve inhibitor for inhibiting operation of the sensing valve, the inhibitor comprising:a sensing delay valve and control comprising a moveable member,a sensing delay volume, the pressure within which controls operation of the inhibitor, the control being arranged to close the sensing delay valve as it moves when the pressure in the sensing delay volume rises above a first predetermined level, and to open the valve as it moves when the pressure in the sensing delay volume falls below a second predetermined level,a delay line through which the sensing delay volume is pressurized by gas flow when the main control valve is open, anda delay timer comprising a flow restrictor and vent line connected to the sensing delay volume for controlling the sensing valve inhibitor to inhibit operation of the sensing valve for a predetermined period following the delivery of the pulse of gas to the outlet. 11. A conserving device as claimed in claim 10 wherein the sensing valve further includes a sensing volume, a connection between the sensing volume and a user, and a control for opening the sensing valve when the pressure in the sensing volume is negative, indicating inhalation by the user. 12. A conserving device as claimed in claim 11 wherein the connection comprises a line connecting the sensing volume to the user supply line. 13. A conserving device as claimed in claim 11 for connection to a twin-tube cannula, wherein the connection comprises means for connecting the sensing volume to one tube of the twin-tube cannula, and the outlet is connected to the other tube of the twin-tube cannula. 14. A conserving device as claimed in claim 11 wherein the sensing delay valve is connected between the user supply line and the sensing volume so that, when closed, the sensing delay valve prevents the sensing valve from sensing the pressure in the user supply line. 15. A conserving device as claimed in claim 10 wherein the sensing delay valve is connected between the main control volume and the sensing valve so that, when closed, the sensing delay valve isolates the sensing valve and prevents it from changing the pressure in the main control volume. 16. A conserving device as claimed in claim 10 wherein the inhibitor comprises an inhibiting member which is moveable between a first position, in which it prevents operation of the sensing valve, and a second position in which it does not prevent operation of the sensing valve, according to the pressure within the sensing delay volume. 17. A conserving device as claimed in claim 16 wherein the inhibiting member is linked to the moveable member so that, as the pressure in the sensing delay volume changes, the moveable member moves and causes movement of the inhibiting member from its first to its second position, and vice versa.