Abstract:
A portable warm air humidifier for delivery to a room a steam air mixture of uniform moisture and at a temperature that does not cause sensation of pain. A steam ejector is used to mix the steam from an evaporation chamber with the air entering the humidifier with the advantage, among others, of eliminating the need for motors and blowers. A difference in the water level between a water supply compartment and the evaporation chamber provides a constant pressure in the evaporation chamber which is necessary to drive generated steam through a steam nozzle communicating with the steam ejector. The dimensions of the steam nozzle are determined in relation with the rate of steam generation in accordance with steam velocity to effectively eliminate or minimize the noise normally associated with the passage of steam through a nozzle. The invention is also well utilizable in a humidifier having a filter medium to filter particulates from the air notwithstanding the drop in pressure of the air across the filter medium from the outside to the interior of the humidifier.

Description:
[0001]     The invention relates to a portable, electric air humidifier, more particularly to an improved warm-air humidifier.  
         [0002]     This application is a continuation-in-part of applicant&#39;s pending U.S. patent application Ser. No. 07/606,938 filed. Oct. 31, 1990, which in turn is a continuation of applicant&#39;s U.S. Pat. No. 5,014,338 issued May 7, 1991. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]     Air humidifiers have been found to be important in controlling the environment in homes during very dry weather, or in winter whenever outside air of low temperature is drawn inside and heated, causing the relative humidity in the home to be lowered to an uncomfortable degree.  
         [0004]     Portable humidifiers are well known in the art, and may be classified as follows:  
         [0005]     1. Steam generators which comprise a water container and an electric heating element submerged in the water, there being provided safety devices for switching off the current as soon as the water level drops below the heating element. A flow of hot steam is blown directly into the room to be humidified and there is always the danger of a person, especially a child, being scalded whenever he comes into contact with the jet of steam ejected, typically, at a temperature of about 212° F. Furthermore, the container of hot water, when overturned, may cause serious injuries to the person nearby.  
         [0006]     2. Porous medium humidifiers generally include a porous medium structure partly submerged in cold water contained in an open vessel and a blower unit drawing air through the porous medium structure. The porous medium is either in the shape of a disc or a drum with part of the medium dipping into the water, which is slowly rotated while air is blown through the portion above the water level, thus carrying humidity into the room; or it is in the form a stationary body adapted to draw water into the upper non-immersed part by capillary action, from where it is carried into the room by air blown therethrough.  
         [0007]     3. Ultra-sonic humidifier generally comprise a container filled with water which is brough to a vibration by high-frequency vibrator-means which causes the water to be atomized. An air steam directed onto the water surface carries the mist into the room to be humidified.  
         [0008]     The major drawback of both the two latter appliances is the fact that the water staying in the container is not heated to boiling point as in the steam generator and, therefore, is susceptible to the growth of microorganisms which are subsequently carried by the air stream into the room and ingested by the people staying there.  
         [0009]     4. Warm-air humidifiers share the benefits of steam generators in that growth of micro-organisms is forestalled by heating the water to boiling point. Also, warm-air humidifiers avoid the drawback of hot steam entering the room, since in this type of humidifier the steam is carried into the room as a mist mixed with air, at a temperature to be selected by judiciously choosing the ratio of steam and air.  
         [0010]     A typical warm-air humidifier is described in U.S. Pat. No. 4,564,746: it includes a heated evaporation chamber which is enclosed to prevent leakage or damage and a fan adapted for dispersing the generated steam into the room via a cabinet passageway. The evaporation chamber is mounted on tracks which permit its sliding out of its enclosure and is thus easily accessible for cleaning and servicing. The heating element which is operationally enclosed in the chamber is attached to a cover which is likewise movable out of the humidifier cabinet for cleaning and servicing.  
         [0011]     The drawback of this humidifier is its relatively intricate and expensive design: according to the description, the heating element is attached to a movable cover which is provided with flexible tubing and must be moved upwards on vertical tracks in order to clear the top of the water enclosure, permitting the latter to be slide out sideways. It requires a significant amount of space and cannot be serviced except by a skilled person.  
         [0012]     The humidifier disclosed in applicant&#39;s U.S. Pat. No. 5,014,338 and pending patent application Ser. No. 07/606,938 and in the present application have similar or substantially the same structure except as will be brought out hereinafter. For one thing, a steam ejector is provided in the present application which takes the place of the motor driven blower disclosed in applicant&#39;s mentioned patent and pending application. In terms of similar concepts and structure which are common to the mentioned patent, pending application and present application, the various embodiments each employs base means having a water supply compartment separated into a filling compartment and a main compartment which is in communication with an evaporation chamber to provide water thereto for boiling. The evaporation chamber has an enclosure which projects into the main compartment and a heater is carried within the enclosure, the lower edges or the wall of the enclosure is spaced from the floor of the main compartment to form a passageway, whereby water flows therethrough to immerse the heater within the water. Structure, either in the form of removable trays or a displaceable housing containing the evaporation chamber, is utilized to obtain access to the trays or the heater for cleaning purposes.  
         [0013]     Humidifiers employing motor driven blowers, such as is found in applicant&#39;s U.S. Pat. No. 5,014,338 and in pending application Ser. No. 07/606,938 have many benefits and advantages. On the other hand the use of warm air humidifiers utilizing motor driven blowers are at times deemed objectionable when used in nurseries and in bedrooms as being non-conducive to sleep because of the mechanical and aerodynamic noise associated with motor driven blowers. In addition, the presence of high humidity to which motor shafts are exposed creates rusting problems with the resulting binding of the shafts to the bearings. Obviously, this creates expensive maintenance problems and may inhibit the user from obtaining service because of the expense.  
         [0014]     Certain criteria are desired in warm air humidifiers to maximize the desirability and efficiency of such devices for the user. One criterion is to maintain the steam-air mixture at a predetermined temperature which ranges between 37° C. and 65° C. (99° F.-149° F.) where the lower end of the range approximates human body temperature and the upper end represents a value at which the steam air mixture still may be brought into contact with a person&#39;s hand without the sensation of pain. Another criterion is to provide a uniform mixing of air and steam resulting in an even temperature profile at the outlet grille and avoiding non-uniform degrees of air saturation as well as local recondensation on portions of the grill.  
         [0015]     The following relevant prior art has been found in a patentability search: U.S. Pat. No. 4,635,630; Soviet documents no&#39;s. SU1174569A and 883,637.  
         [0016]     Accordingly it is an object of the present invention to provide an improved and novel non-motor driven warm-air humidifier which utilizes a simple and inexpensive structure and still obtains results equivalent to or better than those obtained by humidifiers employing motor driven blowers.  
         [0017]     It is another object to provide an improved and novel humidifier which provides for the proper and uniform mixture of steam laden air having the proper ratio of air and steam and substantially uniform temperature profile at the outlet grille.  
         [0018]     It is a further object to provide an improved and novel humidifier which employs a steam ejector in place of a motor driven blower and which exhibits significantly less objectionable noises than those employing motor driven blowers.  
         [0019]     It is a still further object to provide a novel and improved humidifier which utilizes a steam ejector tube having a restricted throat portion therein and which is dimensioned and positioned in relation to a steam nozzle in which steam flows at a certain velocity and produces a steam air mixture of the proper saturation and temperature substantially noise free or of minimum noise.  
         [0020]     Another object is to provide a novel and improved gravity water-feed humidifier in which the constant pressure to drive the generated steam through a steam nozzle is maintained by a differential head of water existing between the steam generation compartment and the water supply compartment.  
         [0021]     Further objects ad advantages of the present invention will become obvious to one skilled in the art in the following description of the invention and the claims.  
       SUMMARY OF THF INVENTION  
       [0022]     The warm air humidifier, of the present invention, includes an evaporation chamber in the shape of an inverted cup which is provided with a steam nozzle in its top portion and the chamber contains an electric resistance heater close to its open bottom end. In a preferred embodiment, the evaporation chamber is capable of containing only a small volume of water, thus promoting rapid start operation. The open bottom end is immersed in the main compartment of a water supply compartment which also includes a filling compartment supplied with water from a portable jug positioned on a base which includes the water supply compartment. The water supply compartment is kept filled with water to a predetermined level by the jug allowing water to flow into the compartment only as high as the rim of the neck of the jug. The pressure within the evaporation chamber, which is generated by the steam therein, is maintained constant by a differential head which exits between the higher level of the water in the water supply compartment and the lower level of the water in the evaporation chamber.  
         [0023]     Vertically disposed above the steam nozzle is a steam ejector tube having its lower end in spaced proximity to the steam nozzle, whereby steam from the steam nozzle flows through the steam ejector tube. The tube has a narrow and restricted portion which, in operation, creates a region of low pressure to thereby induce a flow of air within the housing to mix with the steam to produce an air-steam mixture. The present invention takes advantage of certain phenomena as follows:  
         [0024]     1. The high velocity jet stream from the nozzle, while flowing through the “still air” in the ejector tube will cause air next to it to move with it through the exertion of a shear-force. That moving air then will carry along with it the adjacent layers of air particles, which in turn carry adjacent layers until the boundaries of the tube are reached. By properly designing and dimensioning and positioning the relevant components involved, entrainment of air with steam to provide a desired ratio of air to steam and temperature may be obtained.  
         [0025]     2. The negative or low pressure created within the steam ejector tube, which is dependent upon the dimensions of the draft; of the tube, will influence the flow of the air to be treated into the humidifier, especially were provision must be made to overcome the pressure drop occasioned by reason of the air having to flow through a filter medium when the humidifier is to remove particulates from the air to be treated.  
         [0026]     3. A “buoyancy” phenomenon is utilized in the present invention. As the steam mixes with the air the mixture becomes warm and humid, thus attaining a specific gravity lower than the surrounding dry cooler air. consequently, the air steam mixture adds another driving component to the flow of the mixture and rises through the tube to enhance the drawing in of fresh or cool air from the bottom of the tube, much as in the well known “atmospheric hyperbolic” cooling towers.  
         [0027]     The preset invention incorporates and utilizes these phenomena to provide a simplified and effective low cost warm air humidifier which minimizes and avoids many of the problems associated with other portable humidifiers, particularly those employing motor driven blowers for mixing air and steam for delivery to a room in which such humidifiers are placed.  
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0028]      FIG. 1  is a vertical section through the warm-air humidifier of the invention and through an inverted water container in position on the base means of the humidifier;  
         [0029]      FIG. 2  is a vertical section through the bottom portion of the humidifier illustrated in  FIG. 1 , showing the tray in lowered position ready for removal;  
         [0030]      FIG. 3  is a section through the warm-air humidifier along line A-A of  FIG. 1 ;  
         [0031]      FIG. 4  is an enlarged fragmentary vertical section through the top portion of the humidifier illustrated in  FIG. 1 ;  
         [0032]      FIG. 5  is a vertical section of a second embodiment of the warm-air humidifier containing a hinged evaporation chamber, shown in position on the base means;  
         [0033]      FIG. 6  is a vertical section of the warm-air humidifier  FIG. 5  showing the evaporation chamber displaced away from the base means;  
         [0034]      FIG. 7  is a section in elevation, of a third embodiment of the present invention;  
         [0035]      FIG. 8  is a section, in elevation, taken along the line  7 - 7  of  FIG. 7 ;  
         [0036]      FIG. 9  is an enlarged view of the steam ejector tube and of the steam nozzle to graphically show the flowing streams of steam and air; and  
         [0037]      FIG. 10  is a graphical representation of a velocity distribution plot of the phenomena occurring within the steam ejector tube of  FIG. 9 :  
         [0038]      FIG. 11  is an isometric view of the tray shown in  FIGS. 7 and 8 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0039]     The components of the warm-air humidifier, as shown in  FIGS. 1 and 2 , are enclosed in a housing I including a base portion  1  and a top portion  2 , the base being configured to support a water jug II in upside-down position. The base contains a drawer III of trapezoidal cross section which forms together with a sloping inner wall  10  of the base, a “V”-shaped trough  11 . A tray IV is supported by the respective sloping walls  10  (of the housing) and  50  (of the drawer), whereby the contours of two opposite side walls  40  and  41  of the tray correspond in slope to the inclination of the two walls, while the tray bottom  42  is substantially flat. The tray includes a main compartment  43  and a filling compartment  44 , in proximity to the drawer wall  50 , which are separated by a partition  45  perforated by a connecting port  46 . A vertical pin  47  projects from the bottom of the filling compartment and connects with a spring-supported valve  20  in the neck opening  22  of the inverted jug II. In order to keep the drawer in position inside the housing a tongue  38  projects upwardly from the bottom of the housing and engages an opening  39  in the bottom of the drawer when this is in closed position.  
         [0040]     The top portion of housing  2  includes an evaporation chamber  30  in the shape of an inverted cup which extends into the base portion  1  and into the main compartment  43  of the tray, stopping short of the flat bottom  42  with a narrow gap remaining between the lower rim of the chamber and the bottom. The chamber top is stepped, forming a higher portion  31   a  which contains a steam nozzle  32 , and a lower portion  31   b  into which a flask-shaped member  33  is inserted and hermetically closed to prevent steam from escaping therethrough. Member  33  holds a thermostatic switch  35 , as well as a set of levers  36  serving for resetting the switch by means of knob  37 . The tray, as well as the bottom of the evaporation chamber is filled with water, its upper level being defined _, the lower rim  21  of the valve  22  in the neck of the jug II. An electric heater  34  is fully immersed in the water, and is held at its raised portion  34   a  in intimate contact with the member  33  by means of a clip  52 . The heater is switched off as soon as the water level drops below the raised portion  43   a  of the heating element due to lack of water in the jug.  
         [0041]     For operation of the humidifier, the jug II, full of water, is placed with its valve  22  onto the filling compartment whereupon the pin  47  urges the valve body  20  upwards off its seat and permits water to flow into the tray. Water flows out of the filling compartment  44  into the main compartment  43  through the port  46  in the partition  45 , the level being defined by the rim  21  of the jug&#39;s neck; for the reason that no air can flow into the jug through the neck as soon as it is covered by water and, obviously no water can flow out.  
         [0042]     Due to evaporation, the water level in the tray will drop below the height of the rim of the jug, permitting more water to enter the tray and keeping it filled to the predetermined level. For the purpose of cleaning the tray, the drawer III is pulled out of the housing, causing the tray to slide down along the inclined wall  10  of the housing as shown in  FIG. 2  of the drawing. At the same time, the pin  47  in the filling compartment is taken out of contact with the valve  20  of the jug, thereby closing the neck opening and preventing water from flowing out into the tray. The drawer III can now be withdrawn from the housing and the tray IV can be taken out.  
         [0043]     A vertically disposed steam ejector tube  84  is provided within housing I immediately above the steam nozzle  32 . Tube  84  is made of any suitable material and preferably may be formed from a plastic, such as, polypropylene, which is molded to the preferred shape disclosed. At its lower portion tube  84  is flared outwardly and then narrows to a throat  86  and thereupon the tube flares outwardly and towards the top  88  of top portion  2  of housing I. Top  88  has an outlet opening  90  ( FIG. 1 ), the walls of which seat the circumferential edge of tube  84  at that point. A grille  92  is provided at opening  90  to direct the flow of air from tube  84  and into a room. Housing I may also include side wall  94  having a removable air filter  7 .  
         [0044]     Since the compartment  43  and  44  are in liquid communication with each other the water level in both compartments will be the same height. When heating element  34  is energized, the water in compartment  43  and particularly in evaporation chamber  30  begins to boil and steam is formed. The pressure of the generated steam, as present in the space in evaporation chamber  30 , forces the level of water therein to a level below the level of the water in compartment  43  outside of evaporation chamber  30  and in compartment  44 , to provide a differential head which in effect maintains the pressure within evaporation chamber  30 . This pressure forces or drives the steam out of evaporation chamber  30  through steam nozzle  32  at a predetermined velocity. The existing steam then flows up into steam ejector tube  84  where it enters throat  86 . The restricted dimensions of throat  86  create a region of low pressure, which in conjunction with other phenomena to be described hereinafter, sucks or draws air in from the interior of housing I to form a steam-air mixture which discharges through outlet opening  90  in the top  88  of the top portion  2  of housing I.  
         [0045]     The use of the steam ejector concept in the present invention requires an understanding of certain phenomena which makes practical the application of this concept to gravity feed portable warm air humidifiers. A steam ejector requires a high velocity of steam from a nozzle ad through an ejector tube in order to provide a proper mixture of steam and air having the desired ratio, as well as temperature. Firstly, a consideration of the steam velocity should be made, it being known that the velocity of steam through the nozzle is a function of the following: 
        A=The cross-section area of the nozzle expressed in centimeters squared (cm 2 )     G=Rate of steam generation in grams per second (Gr/sec)     ρ=The density of the steam in grams per centimeter cubed (g/cm 3 ) 
 
 Thus: 
 
 V ( cm/sec )= G +(ρ× A ) 
 
 The rate of steam generation is a direct function of the power input 
 
 G=K×EP  
 
 Where 
        EP=electric power in watts     K=a constant dependent on the latent heat of water and 
 
 According to Bernouli&#39;s equation, the pressure required to drive this steam through the nozzle at a velocity (V) is 
 
 P÷ρ=V 2+2  g (g=gravitational acceleration) 
 
 Applying the foregoing to the present invention, the pressure (ΔP) within evaporation chamber  30 , translates to a difference in water level (ΔH) by which the water level in evaporation chamber  30  is lower than the water level in compartments  43  and  44  which supply water to evaporation chamber  30 . As will be obvious from the description above, as the water is boiled off in evaporation chamber  30 , the water therein slowly recedes. This causes water to seep into evaporation chamber  30  from compartments  43  and  44  and through the space between the lower edges of evaporation chamber  30  and bottom  42  in compartment  43  to replenish the water boiled off. In the structure of the humidifier employed, it is found that the head available is in the range of ½″ to ¾″ or 1.25 cm to 2.0 cm which furthermore provide steam velocities of 1,000 to 3,000 feet per minute (fpm) or 5-15 meters per second (m/sec). Since an objective of the present invention is to reduce the noise of operation of a humidifier, steam velocities through steam nozzle  32  are of a humidifier, steam velocities through steam nozzle  32  are maintained below 2,000 fpm, or a rate of steam flow below 0.5 gr/sec cm 2  because to go above it would result in objectionable “hissing” sounds. 
   
 
         [0051]     The action of the steam flow through ejector tube  84  to produce the desired results with the present invention may be explained by reference to  FIGS. 9 and 10 . In  FIG. 9  the steam jet emerging from steam nozzle  32  is at a high velocity and after leaving the nozzle enters an area known as “vena contracta” whereupon it starts diverging. The steam jet while traveling through the “still” air causes the air next to it to move with it through the exertion of sheer-force.  
         [0052]     The movement of air next to the steam jet will carry along the air particles next to it, and so on, until a velocity profile as shown in  FIG. 10  is achieved. As the steam jet moves further away from the nozzle it expands and entrains the air until a substantially uniform mixture of air and steam is established in an around the narrowest area of the tube, which is the throat  86 . As the mixture passes the throat and moves towards the upper end of the tube, the mixture rises due to the upwards impetus provided by the steam and by the buoyancy of the warm, moist air mixture which is lighter than dry cool air.  
         [0053]      FIG. 10  illustrates, in a graphic manner, the air and steam velocity distribution as measured along the “ref. line” of  FIG. 9 . The line described as “velocity profile” is the locus of all the individual velocity measurements taken along the “ref. line” of  FIG. 9 . It should be noted that along the “ref. line” there is still very little mixing of air and steam and therefore a region of pure steam and pure air can be identified, as pointed out by the terms “steam” and “air”.  
         [0054]     It was found in constructing the humidifier of the subject invention that certain dimensions of the ejector tube  84  had to be adjusted as follows:  
         [0055]     As was brought out above, the rate of steam flow out of steam nozzle  32  is preferably maintained below about 0.5 gr/sec cm 2 . Furthermore, in order to obtain an outlet moist air temperature between about 42° C. and about 65° C., the ratio between the throat diameter and the distance of throat  86  from the steam nozzle  32  should be in the range of about 0.5 to about 0.75.  
         [0056]     Moreover, it was also determined that the ratio of the diameter of the steam nozzle  32  to that of the throat of the ejector tube  84  should be in the range of about 0.1 to about 0.25.  
         [0057]      FIGS. 5 and 6  show another embodiment of the present invention. In this warm-air humidifier, top portion  2  is hinged, allowing easy access to the tray IV. In  FIG. 5 , illustrating the resting of the top portion  2  on the base portion  1 , the lower portion  31   b  of evaporation chamber  30  is surrounded by the tray IV area. A hinge assembly, comprising a hinge  71  and a hinge support member  70 , are attached to the jug support platform  72 , allowing the top portion  2  of the housing I to be moved to an open position, as shown in  FIG. 6 . These figures also show an embodiment of the invention which does not include a drawer. In this embodiment, base  60  supports the tray bottom  42 . When the top portion  2  is moved to its open position, the tray IV is exposed, allowing its easy removal.  
         [0058]     A third embodiment of the present invention is disclosed in  FIGS. 7 and 8  incorporates much of the components and concepts found in  FIGS. 1 through 6  and  FIGS. 9 and 10  except for some slight differences in structure as will become apparent from the description that follows.  
         [0059]     Referring now to  FIGS. 7 and 9 , the portable warm-air humidifier is generally designated by the reference character  112  and includes a water container  114  disposed in juxtaposition with a housing  116 , both of which are seated on a base  1116  provided with feet  120  for placement on a fiat surface (not shown). Water container  114  is provided at its top ( FIG. 7 ) with a convenient handle  122  situated in a recess  124  to permit the manual grasping of the handle  122  to remove and carry the container from base  118 . The bottom of container  114 , as better seen in  FIG. 7 , has a neck  126  with external threads  128  on which a cap  130  may be tightened. A spring biased valve  132  (springs not shown) having a valve steam  133  disposed in cap  30  and is normally biased for seating on the walls  134  of an opening  136 . Extended wing members  138  are provided to assist in the screwing and unscrewing of cap  130  from neck  126 . After the container is filled and capped it is positioned as shown in  FIG. 7  where it is supported on base  118  on integrally formed hollow projects supports  139  (one shown in  FIG. 7 ).  
         [0060]     Base  118  is substantially hollow and accommodates a removable tray  140  (shown in  FIGS. 7, 8  and  11 ) resting on a floor  144  of base  118  and the tray has a filling compartment  142  to receive neck  126  of container  114 . Tray  140  corresponds to tray IV in the first and second embodiments herein as seen in  FIGS. 1-6 , in terms of each being easily assessed and removable for cleaning. Furthermore, the trays of each embodiment has a filling compartment and a main compartment. A floor  145  of compartment  142  has an upstanding molded pin  146 . As seen in  FIG. 7 , when container  114  is positioned on base  118 , pin  146  engages valve steam  133  to displace valve  132  upwardly, permitting water to flow from the container through opening  136  into a filling compartment  142  of tray  140 . Tray  140  has a second or main compartment  150  formed integrally with compartment  142 , to the left of the latter as seen in  FIG. 7 . An upstanding post  152  is formed integral with floor  144  of base  118  and is positioned between compartments  142  and  150  between upstanding walls  154  of tray  140 . Compartment  142  is substantially circular in horizontal cross section to accommodate neck  126  whereas compartment  150  is substantially rectangular in horizontal cross-section. Compartments  142  and  150  of tray  140  are in communication with each other in that water from compartment  142  readily flows therefrom into compartment  150 , whereby the level of water in compartment  150  will always be a the level in compartment  142 .  
         [0061]     Housing  116  is provided with a rectangular shaped floor  160  which substantially seals oft the interior of housing  116  from compartment  150  of tray  140  except for an opening in which the lower portion of a steam nozzle  162  is seated. As better seen in  FIG. 8 , nozzle  162  has an enlarged circular lower portion  164  leading to a narrowed and substantially cylindrical jet opening  166 . Floor  160  has integrally formed therewith a depending wall  168  which extends perimeterically of the floor and projects downwardly into compartment  150  of tray  140  to form an evaporation chamber  169 . The wall  168  is positioned in close proximity to the walls  170  of compartment  150 . The lower edges of wall  168  also extend close to the floor  145  in compartment  150  but are spaced therefrom as to permit water in tray  140 , and particularly compartment  150 , to readily flow between compartment  150  and evaporation chamber  169 . An electrical heating element  172  is provided in evaporation chamber  169 , which when energized, heats the water to boiling to generate steam therein which escapes chamber  169  through steam nozzle  162 . A plate or baffle  174  is secured adjacent to lower portion  164  of nozzle  162  and in the path of flow of steam to interrupt and minimize the discharge of water droplets from the compartment with the steam, as well as to muffle to some extent, the boiling sound of water.  
         [0062]     The outer sidewalls  204  of housing  116  has an extension or lip  206  which projects below floor  160  and into compartment  150  of tray  140  for engagement by a latch  208  which is mounted on post  152  for pivotal movement by a screw  210 . When container  114  is removed from base  118 , access may be obtained to latch  208 , to pivot it out of engagement with lip  206  to permit the housing  116  to be lifted off of base  118  and thereby allow access to heater element  170  for purposes of cleaning and the like.  
         [0063]     The present invention as embodied in the third embodiment shown in  FIGS. 7 and 8  operates in similar manner as the first two described embodiments in the generation of steam in admixture with air, the humidifier of the third embodiment, as is obvious from the description and explanation hereinbefore, differs in that the housing containing the evaporation chamber may be removed completely from the base whereas in the second embodiment the equivalent structure is pivoted to the base as ar  71  (see  FIGS. 5 and 6 ). It is apparent that there is no basic change in concept in that either structure permits displacement of the evaporating chamber from the base to obtain easy access to the heater element. Also, the latching structure which includes latch  208  and lip  206 , permits the positive latching of housing  116  on the base  118 .  
         [0064]     Steam ejector tube  84  preferably is in the configuration disclosed in the drawings although the present invention contemplates the usage of a steam ejector tube which is straight or angled (rather than curved) or which does not have a restricted throat portion. However, these variations would result in a loss of efficiency of tube  84  as would be understood from reading points  1 ,  2 , and  3  in the “summary of the invention” in this patent.  
         [0065]     In terms of modifications of the structure disclosed hereinbefore, the present invention also contemplates an evaporation chamber in which the lower wall engages the bottom of the tray rather than spaced therefrom. In such event, openings would be provided circumferentially of the lower wall to permit water to enter the evaporation chamber from the main compartment. Although the operation of the humidifier of the present invention would not materially change, a problem would arise in that the openings, in time, would become clogged by deposits from the water or other liquids used, to thereby impede the flow of water between the main compartment and the evaporation chamber.  
         [0066]     From the foregoing, it is apparent that the present invention provides an improved and novel humidifier which utilizes a simple and effective steam ejector tube in combination with a steam nozzle through which a high velocity jet is produced under the constant pressure by reason of a differential head of water in the water supply compartment as constituted by the main compartment and the filling compartment of the base.  
         [0067]     By utilizing the phenomena of entrainment, negative pressure and buoyancy a uniform and desired mixture of steam and air at a temperature below the painful range is obtained without the use of relatively expensive motor driven blowers and the like, as well a components with moving parts. The invention thus obviates the need of fans, motors, electric controls and the like, and the assembly costs required of them as well as maintenance costs. Furthermore, the pressure drop through the air filter, where used, is overcome by the present invention which adds to the value of same.  
         [0068]     Although several embodiments of the present invention have been disclosed and described herein, it may be readily understood that other variations of the invention may be practiced which still will be embraced by the spirit of the invention and covered by the claims which follow.