METHOD AND APPARATUS FOR PRODUCING A STREAM OF HEATED VAPOR PARTICULARLY USEFUL FOR THERAPEUTIC PURPOSES

Abstract: A method and apparatus for producing a stream of heated vapor involve the steps of operating an ultrasonic generator (74) while submerged in a pool of the liquid to be vaporized in a chamber (14) to produce a spout (76) of inten­ sely-agitated liquid spouting upwardly out of the surface (22) of the liquid in the chamber (14); directing a confined stream of hot gas into the chamber (14) to impinge the liquid spout (76) and to thereby vaporize liquid therein; and outletting from the chamber (14) a confined stream of hot gas saturated with the vapor and mixed with a small quantity of liquid dro­ plets. The described method and apparatus are particularly useful for treating the common cold by applying the so produced stream via a delivery tube (80), with the stream so shaped and pressurized that the stream is propelled to the nasal mucosa.

Description: The present invention relates to an apparatus for producing a stream of heated vapor according to the preamble of claim 1. The invention is particularly useful for therapeutic purposes, and is therefore described below with respect to this application. It has recently been shown that the application of a stream of heated vapor to the nasal passages can have a beneficial therapeutic effect on persons suffering from a common cold and other similar ailments such as sinusitis, allergic and non-allergic rhinitis, nasal polyps, asthma and hay fever. Several patents, for example US-A-4,369,777 and 4,401,114, have issued describing this treatment, and machines are now commercially available for providing this treatment. However, while the treatment has been found to be very effective, the machines now in use are large and noisy, tend to overheat at the entrance to the nostril, tend to produce considerable water splash, are frequently unreliable, and are very expensive. US-A-3,469,785 discloses an apparatus for producing a stream of vapor comprising a chamber adapted to receive a quantity of liquid to be vaporized; an ultrasonic generator disposed within the chamber to be submerged within the liquid when received therein; drive means for driving the ultrasonic generator to produce a spout of intensely-agitated liquid spouting upwardly out of the surface of the liquid in the chamber; gas feeding means for feeding a gas into the chamber; and a delivery tube connected to the chamber for outletting vapor therefrom in the form of a confined stream of gas saturated with the vapor and having a small quantity of liquid droplets mixed therein. In the apparatus described in US-A-3,469,785, the ultrasonic generator is disposed substantially in the horizontal plane so that the intensely-agitated liquid spouts substantially vertically out of the surface of the liquid in the chamber. Air is admitted into the liquid chamber and is circumferentially swirled therein. The fall-back of droplets from the spout into the liquid pool disturbs the formation of the spout, and thereby decreases the nebulizing capacity of the device. In US-A-3,901,443 the ultrasonic generator is mounted at an inclination of 2-22° with respect to the surface level of the liquid in order to minimize the disturbance to the formation of the spout by the fall-back of the droplets from the spout into the liquid pool. US-A-4,410,139 provides a partition surrounding the spout in order to separate the larger non-vaporized particles from the spout base to reduce the disturbance to the formation of the spout at the spout base. In EP-A-0 125 210 hot air is blown through a porous member having an end immersed in a liquid. The object of the present invention is to provide an improved apparatus for nebulizing a liquid in a manner which substantially increases the nebulizing capacity and also minimizes the disturbance to the formation of the spout by the fall-back of droplets from the spout into the liquid pool. To achieve this, the apparatus for producing a stream of heated vapor according to the invention is characterized in that the gas feeding means feeds the gas into the chamber in the form of a confined stream of hot gas impinged directly on the liquid spout to impart an arcuate trajectory to the spout. Such an arrangement has been found to increase the nebulization from the spout by the increased area of the spout contacted by the hot gas because of the arcuate trajectory of the spout, and by the reduced disturbance to the formation of the spout at the spout base because of the shifting laterally, with respect to the spout base, of the fall-back into the pool of larger liquid droplets from the spout. The apparatus is particularly applicable wherein the liquid is water, e.g. distilled water or saline water, and the gas is air. Apparatus constructed in accordance with the above features has been found to provide significant beneficial therapeutic effects on persons suffering from the common cold and other nasal elements. In addition, such apparatus operates with very little noise, and provides a substantially uniform temperature from the hyper-evaporation chamber to the entrance to the user's nostrils, thereby minimizing the possibility of irritating or damaging the person's nostrils by an unduly high temperature. It has also been found that a significantly higher temperature can be achieved in the stream reaching the nasal mucosa, without undue discomfort to the user. Further, the stream of vapor is sufficiently moist to keep the nasal tissues moist, and thereby to minimize irritation or damage, but not so moist as to produce water splash. Still further, such apparatus has been found to be very reliable and significantly less expensive than the apparatus now in use. Additional features and advantages of the apparatus for producing a stream of heated vapor will be apparent from the description of the accompanying drawings, wherein: Fig. 1 is a three dimensional view illustrating one form of apparatus for producing a stream of heated vapour; Fig. 2 is a front elevational view of the apparatus of Fig. 1; Fig. 3 is a three dimensional view illustrating the apparatus of Fig. 1 from the opposite side; Fig. 4 is a view along lines IV--IV of Fig. 3; and Fig. 5 is a fragmentary view illustrating a variation. The apparatus illustrated in the drawings comprises a housing, generally designated 2, of appropriate material such as plastic, supported on rubber feet 3. Housing 2 includes a partition 4 extending the full vertical height of the housing and dividing its rear end into two compartments 6 and 8 each extending the complete vertical height of the housing. A rotary pump, generally designated 10, is disposed within compartment 6 and pumps air to a duct 12 disposed within compartment 8. Communicating with duct 12 is a chamber 14 located at the front side of the apparatus and defined by a vertical rear wall 16 separating the chamber from compartment 8, a front vertical wall 18, a bottom curved wall 20, and a top curved wall 23. Compartment 14 is adapted to receive a quantity of a liquid, namely water in the described preferred embodiment, to a level indicated at 22 in Fig. 1. The water introduced into compartment 14 is supplied from a water reservoir 24 constructed as a separate container and sealed from the atmosphere except for a valve assembly, generally designated 26, having a depending operator stem 28. Valve assembly 26 is of a known construction and is normally closed, but is automatically opened by its operator stem 28 passing through an inlet port 30 in housing 2 and engageable with a ledge 32 formed in the housing. When reservoir 24 is so applied to housing 2, thereby opening valve 26, the water is automatically fed from reservoir 24 through port 30 into chamber 14 to the level 22, namely the level of the lower face of housing wall 34 formed with the inlet port 30. As also known in valve assemblies of this type, the water is automatically maintained at level 22. Such valves are commonly used in kerosene lamps and the like. As shown particularly in Fig. 3, pump 10 disposed within compartment 6 is of the rotary type, including a disc 40 formed with a circular array of radially-extending vanes 42 rotatably mounted within a housing 44 fixed to partition 4. Housing 44 is formed with a central opening 46, and vanes 42 include extensions 48 extending through opening 46 into extension 50 of housing 44. Extension 50 is also formed with a central opening 52 communicating with the interior of the pump compartment 6. Rotary pump 10 is rotated by an electric motor 54 disposed within a compartment 56 at the front of the apparatus just underlying the liquid reservoir 24. As shown in Fig. 4, motor 52 drives a shaft 57 having a pulley wheel 58 coupled by a pulley belt 60 to another pulley wheel 62 secured to rotatable disc 40 of pump 10. Motor 54 is preferably a shaded-pole induction motor operating at a rotational speed of 3000 RPM when supplied from a 60 cycle power source, and the transmission ratio between pulleys 58 and 62 is such that rotary disc 40 is driven at a speed of 6000 RPM. Air is inletted into pump compartment 6 via a grill section 64 (Fig. 3) integrally formed with housing 2 at its lower rear end. A porous filter, such as of foam rubber (not shown), may be supported on grill 64 to filter the air inletted into compartment 6. A portion of the air is pumped by pump 10 through an outlet opening 66 formed at the lower end of partition 4 into conduit 12 for conduction by the conduit to the hyper-vaporization chamber 14 at the front end of the apparatus. Another portion of air is pumped by pump 10 via an opening 67 into compartment 56 for cooling the electric motor 54. The latter compartment is also integrally formed with a grill 68 for exhausting this cooling air. Conduit 12, conducting the air pumped by pump 10 into chamber 14, includes an electrical heater 70 which heats the air passing therethrough so that the air exiting from conduit 12 into chamber 14 is at a high temperature. This air exits from the conduit into chamber 14 via an outlet nozzle 72 oriented so as to direct the heated air downwardly into chamber 14. Chamber 14 includes an ultrasonic generator 74, in the form of a piezoelectric crystal, disposed within the chamber so as to be submerged by the liquid when received therein to the level 22. Piezoelectric crystal 74 may be of the type commonly used in ultrasonic humidifiers. Preferably, it is operated at a voltage of 120 volts (peak-to-peak) and at a frequency of 1.6 mHz, and it agitates the liquid within chamber 14 such as to produce a spout of intensely-agitated liquid spouting upwardly, as shown at 76, out of the liquid surface and falling back by gravity to the liquid surface. Such spouts are also formed in ultrasonic humidifiers using piezoelectric crystals. As distinguished from ultrasonic humidifiers, however, in the present invention a confined stream of hot air, as generated by pump 10 and heated by heater 70, is directed by a conduit 12 and its outlet 72 to impinge the liquid spout 76. This produces an instant vaporization of liquid within the spout 76 so that the air within chamber 14 is completely saturated, i.e. of 100% humidity, and also includes a quantity of water droplets having an average diameter of 4-8 microns. In addition, the pressure within chamber 14 is increased 5-20 cm (water), preferably 10 cm, above atmospheric pressure, which is at least one order of magnitude above the pressure increase (about 0.5 cm) in a conventional humidifier. Chamber 14 is provided at its upper end with an outlet 78 connected to one end of a flexible delivery tube 80. The opposite end of delivery tube 80 is closed by a cap 84 formed with a pair of parallel, restricted passageways 86, 88, spaced so as to be alignable with the two nostrils of a user of the apparatus. Outlet 78 and delivery tube 80 thus produce a confined stream of heated air of 100% humidity and including a quantity of water droplets of very small diameter, which stream is split into two streams by passageways 86, 88. The two streams enter the two nostrils of the user with sufficient pressure, e.g. 5-20 cm (water), to reach the nasal mucosa without inhalation by the user. The illustrated apparatus further includes a heat sensor 90 (Figs. 1, 2) at the outlet end of chamber 14 to measure the temperature thereat. Heat sensor 90 controls heater 70 to maintain a relatively constant temperature at the outlet of chamber 14. Since the air within the chamber is 100% humidified, as described above, there is very little temperature drop in the passage of the heated water vapor stream from chamber 14 via delivery tube 80 to the nostrils of the user. The temperature of the heated water vapor exiting from chamber 14 is preferably within the range of 40-55°C; particularly good results have been obtained when this temperature is 49°C. The delivery tube 80 should be at least 20 cm in length, preferably about 35 cm, which produces a temperature drop of approximately 1.5°C. Another temperature drop of 1-3°C may occur during the passage of the vapor stream to the nasal mucosa, depending on whether cap 84 is held against the nostrils, which is comfortably permitted in the illustrated device, or spaced slightly (e.g. 1 cm) therefrom. As described above, heat sensor 90 at the outlet of chamber 14 maintains this temperature relatively constant, and the temperature drop during the travel of the heated stream of air via delivery tube 80 to the nostrils of the user is very low because the heated air is 100% humidified by the above-described technique. Heater 70 is preferably operated to produce a temperature of 250-400°C, preferably 300°C in the stream of air exiting from nozzle 72 into chamber 14. The water content of the 100% humidified air outletted from chamber 14 via delivery tube 80 is from 75-90% of the total water content of the stream exiting from that chamber; that is, the water droplet content is from 25-10% of the total water content of this stream. The purpose of the water droplets is to maintain the tissues moist and thereby to prevent irritation or damage. If the water droplet content is less than 10%, it has been found that this unduly irritates the tissues and could even cause damage; whereas if the water droplet content is more than 25%, this makes the treatment less effective and also overly wets the tissues so as to cause water to drip from the nostrils. Best results have been obtained when the total water content of the outletted stream is 80% in the humidified air and 20% in the water droplets. The described apparatus also enables the use of saline water, which is not possible with the existing machines. The electrical circuit for operating the pump motor 54, heater 70 and the piezoelectric crystal 74 has not been shown, as conventional circuitry may be used for this purpose. Preferably, the components of the electical circuit are carried by a printed circuit board 92 (Fig. 1) directly mounted to partition 4, which partition also mounts the rotary disc 40 of pump 10. Partition 4 is made of aluminum sheet material in order to act as a heat sink for the heat generated by the electrical components mounted on printed circuit board 92. Cap 84 at the end of delivery tube 80 is preferably removable and replaceable by another cap when the apparatus is to be used by another person. Also, an open-top container 96 is supported by housing 2 to underlie chamber 14 to catch any water drippings, e.g., occurring when the water reservoir 24 is applied. Cap 84, chamber 14, reservoir 24 and delivery tube 80 are all removable for washing. In Fig. 2, piezoelectric crystal 74 is mounted at a slight incline to the vertical axis of chamber 14. Thus, the liquid spout 76 exiting from the surface 22 of the liquid is also at a slight incline to the vertical axis of the chamber, producing a "plume" like appearance. Outlet 72, for the hot air delivered to chamber 14 by conduit 12, is directed downwardly over the spout to produce a concentrated jet impinging the spout about 1 cm from its bottom. The front wall of housing 2 includes one or more light indicators for indicating various conditions. Thus, light indicator 97 indicates whether the apparatus is operating, and light indicator 98 indicates a possible malfunction, such as overheating (or underheating) of the heated vapor stream exiting from chamber 14. The apparatus further includes a plug 99 for connecting same to the supply mains, and a switch 100 for turning the apparatus "on" and "off". Fig. 5 illustrates a variation, wherein the piezoelectrical crystal 74' is mounted precisely along the vertical axis to produce a vertical spout 76', but nozzle 72' is tilted at a slight angle to the vertical axis so as to deflect the spout towards a divider wall 110 laterally of the spout. The humidified air and fine water droplets exit via the outlet 78' (where sensor 90' is located), whereas the larger water droplets fall back on the other side of wall 110 into the water pool. The apparatus illustrated in the drawings operates as follows: Removable reservoir 24 is first filled with water. The dimensions of this reservoir are such that it contains a quantity of water sufficient for a standard one-half hour treatment. For filling the reservoir, it is detached from housing 2 and filled through its valve assembly 26 as known in such valve assembly constructions. The reservoir is then inverted to the position illustrated in the drawings and is applied to the upper end of housing 2, with stem 28 of the valve assembly passing through opening 30 in housing wall 34 until the stem engages ledge 32 of the housing. When this occurs, the valve opens and permits the water within it to flow through opening 30 into chamber 14 where it automatically assumes the level indicated at 22 in Fig. 3. This level, which is even with the bottom face of wall 34 in which inlet opening 30 is formed, is automatically maintained during the operation of the apparatus by valve 26 as known in valves of such construction. Motor 54 is then energized to rotate pump disc 40 via pulley wheels 58, 62 and pulley 60. As indicated earlier, disc 40 is preferably rotated at approximately 6000 RPM. Heater 70 is then energized. A portion of the air inletted into compartment 6 via grill openings 64 is pumped by the vanes on rotary disc 40 into conduit 12 where it is heated by heater 70 and is then directed via outlet 72 downwardly into chamber 14 containing the water to be vaporized. Another portion of the pumped air is passed via opening 67 into compartment 56 to cool motor 54, this part of the air being exhausted via grill openings 68. At the same time that pump motor 54 and heater 70 are energized, piezoelectric crystal is also energized so as to vibrate at a frequency of 1.6 mHz. As known in conventional humidifiers, this produces in the water within chamber 14, a spout of intensely-agiated water which spouts upwardly, as shown at 76, out of the liquid surface and then falls back by gravity into the water. The water within spout 76, constituted of a multitude of highly agitated small droplets of water, is impinged by the stream of hot air outletted from outlet 72 of conduit 12; this hot air instantly vaporizes a portion of the liquid within the spout. The result is that the vapor within chamber 14 is constituted of 100% humidified air containing a small quantity of liquid droplets having an average diameter of 4-8 microns. The interior of chamber 14 is also pressurized by pump 10 to a pressures 5-20 cm (water) above atmospheric, so that the vapor within chamber 14 is outletted from outlet 78 into delivery tube 80 in the form of a confined stream of the hot 100% humidified air. This stream of heated water vapor and water droplets passes through the flexible delivery tube 80 to the cap 82 at the end of the tube. This end is held in contact with, or slightly spaced (no more than 1 cm) from, the user's nose, with openings 86, 88, aligned with the user's nostrils. The heated water vapor exiting from the end of delivery tube 80 is pressurized 5-20 cm (water) above atmospheric, and therefore the heated water vapor passes into the user's nostril at sufficient velocity to reach the nasal mucosa without inhalation by the user since inhalation is frequently difficult or impossible when the user is suffering from a common cold.

Claims: Apparatus for producing a stream of heated vapor, comprising a chamber (14) adapted to receive a quantity of liquid to be vaporized; an ultrasonic generator (74) disposed within said chamber (14) to be submerged by the liquid when received therein; drive means for driving said ultrasonic generator (74) to produce a spout (76) of intensely-agitated liquid spouting upwardly out of the surface (22) of the liquid in the chamber; gas feeding means (12) for feeding a gas into said chamber (14); and a delivery tube (80) connected to said chamber (14) for outletting vapor therefrom in the form of a confined stream of gas saturated with said vapor and having a small quantity of liquid droplets mixed therein; characterized in that said gas feeding means (12) feeds said gas into said chamber in the form of a confined stream of hot gas impinged directly on said liquid spout (76) to impart an arcuate trajectory to the spout. The apparatus according to Claim 1, wherein said gas feeding means for feeding a stream of hot gas to impinge said liquid spout (76) comprises: an air pump (10) pumping said gas via a conduit (12) into said chamber; and a heater (70) enclosing said conduit (12) so as to heat the gas flowing therethrough from the air pump (10) into said chamber (14). The apparatus according to Claim 2, wherein said air pump (10) is a rotary pump effective to pressurize said chamber (14) to a pressure of 5-20 cm of water above atmospheric pressure. The apparatus according to Claim 1, further including a reservoir (24) for the liquid, and valve means (26) for automatically controlling the flow of said liquid from the reservoir (24) to said chamber (14) so as to maintain a substantially constant level (22) in said chamber (14). The apparatus according to Claim 4, wherein said apparatus includes a housing (2) defining said chamber (14), said reservoir (24) being a separate container receivable on said housing and including a normally closed valve (26) having a valve operator (28) automatically opening said valve to cause the liquid in said reservoir (24) to flow into said compartment (14) upon the application of the reservoir (24) to said housing (2). The apparatus according to Claim 1, wherein said gas feeding means for feeding a stream of hot gas to impinge said liquid spout (76) in said chamber (14) comprises a pump (10) driven by a rotary electric motor (54) for pumping said gas via a conduit (12) into said chamber, and a heater (70) enclosing said conduit (12) to heat the gas flowing therethrough from the pump (10) into said chamber (14), said housing (2) including partition walls (4) defining a first compartment (6) for said pump, and a second compartment (8) for said motor. The apparatus according to Claim 1, wherein said delivery tube (80) is flexible and its opposite end is provided with a cap (84) having a pair of passageways (86, 88) to split the heated stream into two streams for application to the two nostrils of a user. The apparatus according to Claim 1, wherein said ultrasonic generator (74) is a piezoelectric crystal. The apparatus according to Claim 1, wherein said gas feeding means for feeding a stream of hot gases to impinge said liquid spout (76) in the chamber (14) comprises a rotary pump (10) pumping said gas via a conduit (12) into said chamber (14), and a heater (70) enclosing said conduit (12) to heat the gas flowing therethrough from the pump (10) into said chamber (14); and wherein the chamber outlet (78) includes a temperature sensor (90) for sensing the temperature thereat and for automatically controlling said heater (70) to maintain a relatively constant temperature at said chamber outlet (78).

Inventors: VERITY, NIGEL
Applicants: RHINOTHERM NETZER SERENI LIMITED PARTNERSHIP
Application year: 1986
Main classification: A61M15
IPC codes: A61M11, A61M15