Environmental Control Apparatus

Abstract

Apparatus for supplying a controlled atmosphere to a closed chamber. An ultrasonic nebulizer generates liquid particles and the particles are dispersed in air, or in a filtered air-gas mixture, to increase its specific heat. The resulting mixture is then passed through a temperature controlled heat exchanger and into the chamber.

Description

This invention relates generally to an improved atmosphere generator, and particularly to an apparatus for controlling temperature and humidity in a closed chamber, such as a tent suspended over a hospital bed.

At the present time, there is no adequate portable device for supplying a controlled atmosphere to a closed chamber. In most available units, air is recirculated through a power unit comprising a blower, a filter, a heating element, a humidity reservoir, and a cooling chamber. The air is relied upon to maintain the temperature in the controlled chamber and must be recirculated because its specific heat is so low that it is difficult to sufficiently heat or cool the chamber by the air alone without creating objectionable temperature differentials.

Recirculation of the air in the chamber causes several problems. First, the chamber must be sealed to reduce loss of air. Second, there is little or no control over the relative humidity in the sealed chamber, which is simply increased to an indefinite extent by blowing the air over a water reservoir. A third problem will arise when a gas such as oxygen is used with the chamber. Recirculation may cause the gas concentration in the chamber to become too rich.

When the chamber is either a closed room or sealed with a heavy canopy, there may be a noise problem. Blower noise confined within the chamber may be sufficiently high as to disturb the occupant.

A major problem with recirculation type apparatus is the difficulty attending proper cleaning and sterilization. The many irregular surfaces along the air flow path through the power unit are difficult, if not impossible, to clean properly before each use. Poor cleaning combined with high humidity, a stagnant humidity reservoir and relatively high temperatures promote the growth of bacteria and fungi. Recirculation of air within the chamber even with filtering further increases the possibility of undesirable and dangerous growths of the bacteria and fungus cultures.

The apparatus of the present invention includes a portable base, a power unit and a flexible supply duct. Room air is taken into the power unit by a blower and filtered. If necessary, additional oxygen or other gas is then mixed with the filtered air. It is then passed through an ultrasonic nebulizer of the type described in the copending application of Gauthier et al. Ser. No. 626,319, filed Mar. 27, 1967, now U.S. Pat. No. 3,387,607 issued Jun. 11, 1968. The ultrasonic nebulizer disperses fine particles of a liquid in the air. The liquid particles greatly increase the specific heat of the air stream and, as a result, sufficient heat to maintain the desired temperature can be taken into the controlled chamber by a low volume flow of gas, without requiring recirculation.

One use of the environmental control apparatus is in an intensive care unit in a hospital. The flexible supply duct is attached to either a conventional oxygen tent or to a disposable film canopy resembling an oxygen tent. When a disposable film canopy is used, the chamber is prepared for each new patient by merely sterilizing the mattress area and replacing the film canopy. Sterilization of the power unit and the connecting flexible supply duct is required only periodically, because the chamber air is not recirculated. The air which is supplied to the chamber is discharged either through leaks around the canopy or through a controllable vent.

Accordingly, it is an object of the present invention to provide a sanitary, easy to clean, environmental control apparatus.

Another object of the present invention is to provide an air flow apparatus capable of supplying sufficient heat into a closed chamber without requiring air recirculation and which will provide means for accurately controlling the relative humidity therein.

Another object of the present invention is to provide a closed chamber with an accurately regulated oxygen supply.

Another object of the present invention is to provide a silent power unit for supplying a regulated atmosphere to a chamber.

Another object of the present invention is to provide a controlled chamber having a disposable canopy or hood.

Still another object of the present invention is to provide an apparatus capable of supplying air, or an air-gas mixture at a closely regulated temperature and humidity to an oxygen tent for adults.

Other objects and advantages of the invention will become apparent in the following detailed description of a preferred form thereof, reference being had to the accompanying drawings.

FIG. 1 is a flow diagram of the environmental control apparatus of the present invention; and

FIG. 2 is a diagrammatic perspective view of apparatus constructed in accordance with the present invention with the base open to show one arrangement of the power unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the flow diagram of the power unit in FIG. 1 of the drawings, a blower 10 draws room air through a filter 12 and delivers it to an ultrasonic nebulizer 14. The ultrasonic nebulizer 14 disperses liquid into the air, generating an aerosol or an air-suspended fog of small liquid particles. The air and the dispersed liquid particles are then passed through a heat exchanger 16 and into a controlled chamber 18.

The air filter 12 can be either a microfilter or an electronically operated filter. The blower 10 may be of any conventional design, as for example, of the centrifugal or squirrel-cage design having a low noise level.

The filtered air is carried from the blower 10 through an air supply hose 20 to the ultrasonic nebulizer 14. Additional oxygen or other gas, when required, is mixed with the filtered air at this point. The oxygen or other gas is stored under pressure in a gas supply tank 22. A gas hose 24 connects the gas supply tank 22 through a gas regulator valve 26 to the filtered air supply hose 20. It is obvious that a number of gas supply tanks 22 can be used to supply other gases or to provide an oxygen reserve. The gas regulator valve 26 will provide any oxygen concentration needed. The rate of oxygen flow is indicated on a flow meter 28.

The ultrasonic nebulizer 14 is of the type disclosed in the above-mentioned copending Gauthier et al. application. Air, or gas enriched air, is passed through the nebulizer chamber in which a transducer generates a beam of ultrasonic compressional waves in a liquid to cause the liquid, usually water, to break up into an air-suspended fog of dispersed liquid particles which are entrained in the air as it is passed through the nebulizer. The particles have a diameter ranging from about 1 micron to 6 microns. While water is usually all that is required in the atmosphere for a patient, various treatment liquids can be used either as aqueous solutions or otherwise. The dispersed liquid particles greatly increase the specific heat and humidity of the gas and make it possible to carry greatly increased heat quantities to the canopy in comparison with relatively dry room air. A high relative humidity is generally desirable in an environment in which a patient may be placed. A humidity sensor 30 is placed in the chamber 18 and is electrically connected to control the ultrasonic nebulizer 14. The ultrasonic nebulizer 14 is set for whatever humidity is desired in the chamber 18.

A flexible supply duct 32 carries the aerosol from the ultrasonic nebulizer 14 through the heat exchanger 16 and into the controlled chamber 18. The heat exchanger can be a simple coil of copper tubing either wrapped around or inserted within the duct 32. An outer jacket 34 reduces heat transfer to the room. Where the tubing is wrapped around the outside of the duct 32, the jacket can be sealed and filled with a liquid to increase the heat transfer to the aerosol. Heating and cooling fluids are supplied to the temperature regulator 36 from a heater 38 and a refrigerator unit 40. The heater 38 may be a conventional electric water heater although it is not intended to restrict the heating fluid to water. Although the refrigerator 40 can be an electric-mechanical unit, a coil of tubing placed in an ice chamber may operate satisfactorily if there will be only a limited demand for refrigeration of the air.

A temperature sensor 42 is placed within the chamber 18 and is electrically connected to the temperature regulator 36. The temperature regulator 36 is adjusted for whatever chamber temperature is desired. The heating and cooling fluids are mixed by the temperature regulator 36 for the desired temperature. The mixed fluid is then circulated through the heat exchanger 16 by way of pipes 44.

FIG. 2 is a diagrammatic view of apparatus incorporating the power unit of FIG. 1. A base cabinet 46 is mounted on larger wheels 48 for easy transportation and the power unit is mounted within the base cabinet. The gas supply tank 22 is attached by brackets 50 to the end of the base and the brackets 50 are designed to permit easy removal of the gas supply tank 22 for refilling. A standard gas connector 52 is used so that other available oxygen supplies can be used with the apparatus, e.g., an oxygen system built into a hospital and having an outlet in each room can be connected to the apparatus. Doors 54 (shown open) permit easy access to the power unit for servicing and for filling a liquid supply reservoir 56 attached to the ultrasonic nebulizer 14.

One end of the base cabinet 46 has a control panel 58. The oxygen flow meter 28 and regulator valve 26, a temperature indicator 60 and control 62, a humidity indicator 64 and control 66, and a blower control 68 are mounted on the control panel 58. A remote temperature sensor 42 (see FIG. 1) is located in the controlled chamber 18 and is electrically connected to both the temperature regulator 36 and temperature indicator 60. The desired chamber temperature is set with the temperature control 62. A remote humidity sensor 30 is also located in the controlled chamber 18 and is electrically connected to both the ultrasonic nebulizer 14 and the humidity indicator 64. The desired chamber humidity is set with the humidity control 66. Connectors can be mounted on the control panel 58 for attaching the remote temperature and humidity sensors 42 and 30.

It has been found that the standard closed oxygen tent can be replaced with a disposable synthetic resinous film canopy. The canopy is suspended from poles attached to a bed and resembles an oxygen tent. Access to the occupant may be provided through a conventional zipper opening, and the canopy may also have hand openings. It is not necessary that the zipper opening and the hand openings be sealed because temperature controlled aerosol is continually blown into and through the canopy and the air pressure under the canopy is always slightly above ambient pressure so that there is no tendency for room air to flow into the canopy.

The power unit is designed so that it can also be used with a conventional oxygen tent 70 for adult patients by attaching the flexible duct 32 to a sealing ring 72 attached to the tent 70 or the duct 32 can be attached to a sealing ring installed in a film canopy which is suspended over a bed. If necessary, a longer flexible duct can be attached between connector 74 on the heat exchanger 16 and the sealing ring 72 on the oxygen tent 70.

Although the environmental control apparatus has been described in connection with an oxygen tent, it will be appreciated that the apparatus may be modified for use in both medical and nonmedical applications where accurately controlled temperature and humidity are desired for a closed space. For example, if the apparatus is used to supply hot steamy air to a steam bath, the apparatus can be modified by eliminating the refrigeration unit 40 and the temperature regulator 36. It will be appreciated that other power unit arrangements may be used, and that various modifications and changes may be made in the remainder of the elements without departing from the scope of the appended claims.

Claims

I claim:

1. Apparatus for supplying a temperature and humidity controlled environment to an enclosed space, comprising, in combination: means for supplying filtered air under pressure to said space, a reservoir containing a liquid, an ultrasonic nebulizer for dispersing particles of the liquid into the filtered air, whereby the specific heat of the air-liquid particle mixture is such that a desired temperature can be maintained in such space without recirculation of air from such space, a heat exchanger positioned downstream from said ultrasonic nebulizer for changing the temperature of the dispersed liquid particles and filtered air, means operatively connected to said ultrasonic nebulizer and said heat exchanger for sensing and controlling the temperature and relative humidity conditions within such space, conduit means for carrying the dispersed liquid particles and filtered air from said heat exchanger to such space, and means for discharging such mixture from such space to atmosphere whereby the mixture is not recirculated through such enclosed space.

2. The apparatus of claim 1, including: means for supplying compressed oxygen, and means for controllably mixing the oxygen with the filtered air prior to dispersing the liquid particles into the filtered air.

3. Apparatus for supplying a controlled environment to an enclosed space comprising, in combination, blower means for supplying air under pressure, a nebulizer for dispersing liquid particles having a mass means size of between 1 and 6 microns into the air discharged from said blower means, whereby the specific heat of the air-liquid particle mixture is such that a desired temperature can be maintained in such space without recirculation of air from such space, heat exchanger means positioned downstream from said nebulizer for changing the temperature of the air-particle mixture, means operatively connected to said heat exchanger means for sensing and controlling the temperature within such space, said sensing and controlling means including temperature-sensing means operatively connected to said heat exchanger means, means for supplying a cooling fluid to said heat exchanger means, means for supplying a heating fluid to said heat exchanger means, a temperature control means for controlling the flow of said cooling fluid and said heating fluid to said heat exchanger, and means for discharging such mixture from such space to atmosphere whereby such mixture is not recirculated through such enclosed space.

4. Apparatus for supplying a controlled environment to an enclosed space comprising, in combination, blower means for supplying air under pressure, a nebulizer for dispersing liquid particles having a mass means size of between 1 and 6 microns into the air discharged from said blower means, whereby the specific heat of the air-liquid particle mixture is such that a desired temperature can be maintained in such space without recirculation of air from such space and without creating an objectionable temperature differential, heat exchanger means positioned downstream from said nebulizer for changing the temperature of the air-particle mixture, means operatively connected to said heat exchanger means for sensing and controlling the temperature within such space, said sensing and controlling means including temperature-sensing means operatively connected to said heat exchanger means, means for supplying a heating fluid to said heat exchanger means, a temperature control means for controlling the flow of said heating fluid to said heat exchanger, and means for discharging such mixture from such space to atmosphere, whereby such mixture is not recirculated through such enclosed space.