Abstract:
A humidifier has a tank ( 10 ) and a boiling chamber ( 12 ), and a heater ( 14 ) disposed in said boiling chamber. Said humidifier tank and said boiling chamber communicate with each other near said boiling chamber&#39;s top and again near said boiling chamber&#39;s bottom, so that convection and the upward motion of steam bubbles create a circulation of water between said humidifier tank and said boiling chamber. A jet pump ( 38, 40, 42  &amp;  44 ) is disposed in said humidifier tank so that said humidifier tank can be emptied with force, and without requiring water and minerals to pass through a drain valve. A boilover tank ( 54 ) communicates with said humidifier tank at a vertical level above the normal operating water level ( 48 ), so that if steam bubbles reach a specific height in said humidifier tank they will spill over into said boilover chamber. Controls are disposed in said boilover tank for monitoring the amount of water in said boilover tank and generating a signal.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         BACKGROUND  
         [0002]    1. Field of Invention  
           [0003]    This invention relates to steam-type humidifiers.  
           [0004]    2. Description of Prior Art  
           [0005]    Air conditioning systems often include a humidifier to increase indoor humidity. Steam humidifiers boil water and direct the generated steam into the air stream of the air conditioning system. As the water boils, more water is added to the humidifier to keep the water level within a specific range. Any impurities in the water such as oxides of calcium and magnesium, sulfates, chlorides, and bicarbonates of sodium and potassium (to name a few), the presence of which may be unnoticeable in the water source, become concentrated as the water boils in the humidifier. Eventually these impurities precipitate out of the water, which is usually sitting stagnantly in the humidifier tank, and crystallize on the internal components. Floats become weighted and don&#39;t float properly, heating elements become coated and overheat until they burn out, drains become clogged, electrodes become coated and their function impaired, and thermal sensors (such as high temperature limit switches) become insulated from the water.  
           [0006]    This problem has been dealt with in several ways. A mechanism may be provided to drain the humidifier and refill it with fresh water. Many humidifiers do this with a timer, draining themselves every so many hours. Others use electrodes to measure the conductance of the water. When the mineral concentration becomes high, the humidifier controls sense the increased conductivity of the water.  
           [0007]    When the mineral concentration in water becomes high enough, boiling the water produces foam, which in itself is undesirable. Some humidifiers that expose the surface of the boiling water to the air stream of the air conditioning system allow foam to be blown off of the water and into the ductwork, causing rust and mineral deposits to form. U.S. Pat. No. 6,078,729 by Kopel (Jun. 20, 2000) describes an electronic method of detecting the presence of foam in a humidifier by measuring electrical capacitance in the interior top region of the humidifier. As effective as this is, it relies on expensive electronic or even microprocessor controls. Also, by the time water has reached the “foaming” stage, the mineral concentration is beyond that which is required to produce precipitate, and mineral deposits are already forming. Furthermore, the conductivity and capacitance of the water may vary depending on the specific impurities present.  
           [0008]    In any case, once a timer expires or a need for water renewal is otherwise detected, the humidifier is drained. Most humidifiers employ a solenoid valve that opens to allow the water to drain from the humidifier. If, however, minerals have formed and covered the drain opening, no draining occurs. Alternatively, if a piece of mineral or sediment becomes lodged in the valve, the valve may not close, and the humidifier will drain continuously.  
           [0009]    U.S. Pat. No. 4,841,122 by Marton (Jun. 20, 1989) describes a humidifier with a valveless drain, wherein a drainhole at the bottom of the humidifier tank connects to a pipe that extends up the side of the humidifier to a height that defines the maximum water level in the humidifier under static conditions. When additional water is added to the tank, water “overflows” from the top of the pipe, and water from the lower extremity of the tank (which is presumably where any free-floating precipitate would settle) flows into the drainhole, continuing up the pipe and out of the humidifier, so long as water is being added. If, however, the drain becomes covered or clogged, the minimal water pressure created by the water level differential between the tank and the standpipe can do little to push the water out Also, the low velocity water flow is insufficient to keep debris from collecting in the bottom of the drainpipe.  
         SUMMARY  
         [0010]    In accordance with the present invention, a humidifier comprises a method for boiling water such that said water is in continuous rapid motion, a method for detecting the onset of foaming, and a method for purging the humidifier.  
           [0011]    Objects and Advantages  
           [0012]    The objects and advantages of the present invention include:  
           [0013]    (a) To provide a humidifier that keeps water in its tank in constant, rapid motion, thereby reducing the deposit of minerals on internal components;  
           [0014]    (b) To provide a humidifier that can detect the onset of foaming at an early stage;  
           [0015]    (c) To provide a humidifier that can forcefully purge itself of water and minerals;  
           [0016]    (d) To provide a humidifier that requires less periodic maintenance; and  
           [0017]    (e) To provide a humidifier that is more reliable.  
           [0018]    More objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
       
    
    
     DRAWING FIGURES  
       [0019]    It should be noted here that the ensuing preferred embodiment drawings are of a humidifier that was built for the purpose of illustrating and explaining its operation. An actual marketable humidifier would be designed with all components nested as much as possible, for compactness.  
         [0020]    [0020]FIGS. 1 and 2 show the preferred embodiment of the humidifier.  
         [0021]    [0021]FIGS. 2A, 2B, and  2 C show sectional views of the humidifier.  
         [0022]    [0022]FIGS. 3 and 3A show an alternative embodiment of the humidifier tank and boiling chamber.  
                                                         Reference Numerals In Drawings                                10   humidifier tank   12   boiling chamber   14   heating element       16   splash deflector   18   supports   20   water level tank       22   water level float   24   float switch   26   filling solenoid                           valve       28   “boilover” outlet   30   “boilover” trap   32   “boilover” float       34   float switch   36   siphon tank   38   nozzle       40   mouth of purging   42   purging pipe   44   purging solenoid           pipe               valve       46   drain outlet   48   water level   50   supports       52   fill spout   54   “boilover” tank   56   inverted trap       58   steam outlet   60   connecting pipe                    
     
    
     DESCRIPTION  
     FIGS.  2 A,  2 B and  2 C  
     Preferred Embodiment  
       [0023]    A preferred embodiment of the present invention is shown in FIG. 1, FIG. 2, and in the sectional FIGS. 2A, 2B, and  2 C. A humidifier tank  10  has a threaded port in its base for the insertion of a heating element  14 . A boiling chamber  12  is held in place by supports  18  such that the boiling chamber  12  extends above the heating element  14  and slightly above the water level  48 , and the lower end of the boiling chamber  12  is held off of the base of the humidifier tank  10 , and the boiling chamber  12  does not touch the heating element  14 . An inverted cone, a splash deflector  16 , is suspended over the top end of the boiling chamber  12  by supports  50 . A water level tank  20  is disposed adjacent to the humidifier tank  10  and communicates with the same through a tube that exits the water level tank  20  at its bottom and enters the humidifier tank  10  near its bottom, below the water level  48 . A water level float  22  and float switch  24  are disposed in the water level tank  20 . A filling solenoid valve  26  is disposed on a fill spout  52  that protrudes into the humidifier tank  10 . A boilover tank  54  is mounted on the humidifier tank  10  and communicates at its base with a boilover trap  30 . The boilover trap  30  communicates on one end with a boilover outlet  28  and an inverted trap  56  on a second end. The boilover outlet  28  communicates with the humidifier tank  10  above the splash deflector  16 . The inverted trap  56  communicates with a siphon tank  36  that begins at the same vertical level as the water level  48  and extends down a specific length, and is of a specific diameter. The siphon tank  36  reduces in diameter at its base to a specific smaller-diameter connecting pipe  60  which communicates with the humidifier tank  10  near its bottom. An inverted trap, a purging pipe  42 , is disposed on the humidifier tank  10  such that its highest point extends slightly above the waterline  48 . One end of the purging pipe  42  communicates with the humidifier tank  10  near its bottom, this point of communication being designated the mouth of purging pipe  40 . The other end of the purging pipe  40  is open and extends down slightly below the bottom of the humidifier tank  10 . The mouth of purging pipe  40  comprises the discharge portion of a jet pump. The jet portion of the jet pump comprises nozzle  38  disposed on a water tube, which nozzle is positioned appropriately for proper jet pump operation; the nozzle  38  being directed into the mouth of purging pipe  40 . The water tube extends back from the nozzle  38 , up and out of the humidifier tank  10  and is connected to purging solenoid valve  44 . Domestic water piping is connected to solenoid valves  26  and  44 . A steam outlet  58  is disposed at the top end of the humidifier tank. Electrical wires and necessary controls (not shown; prior art) are connected to float switches  24  and  34 , solenoid valves  26  and  44 , and heating element  14 .  
       FIG.  3   
     Alternative Embodiment  
       [0024]    An alternative embodiment of the humidifier is shown in FIG. 3. Instead of the concentric containers comprising the boiling chamber  12  and humidifier tank  10  of FIG. 2A, 2B and  2 C, the humidifier is somewhat “O”-shaped; the left vertical riser serving as the boiling chamber  12 , and the right vertical riser serving as the humidifier tank  10 . The steam outlet  58  and boilover outlet  28  are located over the humidifier tank  10 . The boilover trap and boilover tank, inverted trap, water level tank and siphon tank are not shown because these are unchanged from FIG. 2A.  
       Operation  
     FIGS.  2 A,  2 B, and  2 C  
       [0025]    The humidifier is turned on by a humidistat or other suitable control. The water level  48  in humidifier tank  10  is monitored by the water level tank  20 , which communicates fluidly with the humidifier tank  10  such that the water level in both tanks is equal. When the water level drops in the water level tank  20 , electrical controls connected to the float switch  24  de-energize the heating element  14  and energize the filling solenoid valve  26 , filling the humidifier with water. When the water level float  22  rises to a specific height, the float switch  24  de-energizes the filling solenoid valve  26  and re-energizes the heating element  14 . When the heating element  14  is energized it quickly heats up water in the boiling chamber  12  and steam is generated in seconds. As bubbles of steam form and rise to the top of the boiling chamber  12 , they spill over into the humidifier tank  10 . Water from the humidifier tank  10  flows up into the bottom of the boiling chamber  12  to keep the water levels equal. Gradually the water in the humidifier tank  10  heats up near to boiling as more and more water spills over into it. The bubble formation and spillover become more rapid, and after a few minutes water is circulating very quickly, up through the boiling chamber  12  and down through the humidifier tank  10 . After several hours of operation, the mineral content of the water in the humidifier tank  10  increases to the point that the water&#39;s surface tension is sufficiently increased and the steam bubbles do not pop immediately when they spill over into the humidifier tank  10 . Eventually these bubbles rise far enough up in the humidifier tank  10  that they rise above the splash deflector  16  and reach the boilover outlet  28 . Bubbles that enter the boilover outlet  28  pop and their water collects in the boilover trap  30 . The level in the humidifier tank to which the bubbles rise before popping increases very slowly. The boilover trap  30  and boilover tank  54  fill up quickly, before bubbles rise beyond the boilover outlet  28 . The boilover float  32  rises in the boilover tank  54  and activates the float switch  34 , which is connected to necessary wires and controls that activate a purge cycle. The filling solenoid valve  26  and the heating element  14  are disabled, and the purging solenoid valve  44  is energized. A jet stream of water is directed into the mouth of purging pipe  40 . Water in the humidifier tank and any mineral precipitate or other foreign matter are sucked into the stream and pushed up the purging pipe  42 , which effectively and quickly drains the humidifier tank  10 . Water that leaves the drain outlet  46  has been tempered by the cold water from the jet stream, it is cooled significantly. As the water level in the humidifier tank  10  drops, the water level in the siphon tank  36  also drops, because the two tanks communicate fluidly through a connecting pipe  60 . This creates a partial vacuum over the water in the siphon tank  36 , which siphons the water out of the boilover trap  30  and the boilover tank  54 . When the water level in the boilover trap  30  drops low enough that air can pass over the water in the bottom of said trap, the air breaks the siphon. Residual water in the pipes runs down into the boilover trap  30  and re-seals it fluidly. The boilover float  32  drops and de-activates the float switch  34 . After a short time delay, the purging solenoid valve  44  is deactivated and the heating element  14  and filling solenoid valve  26  are re-enabled. The humidifier fills and begins heating again. An appropriate high-temperature limit device such as a fusible link may be located in the humidifier tank  10  to open the electrical circuit to the heating element  14  in the event the heating relay becomes stuck and energizes said heating element in a low-water or no-water condition. The purging cycle and subsequent fill cycle last less than a minute. Depending on the condition of the domestic water supply, a heating cycle can last 2 to 8 hours between purge cycles.  
         [0026]    The jet pump pumps water and minerals out of the humidifier under pressure, unlike the “open drain” of U.S. Pat. No. 4,841,122 by Marton (Jun. 20, 1989) and does not require the water and minerals to pass through a drain valve as in prior art humidifiers. Mineral precipitate (if any were to form) is much more likely to be “free floating” because of the continuous violent motion of the water during boiling than in prior art humidifiers. The “foam” mentioned in U.S. Pat. No. 6,078,729 by Kopel (Jun. 20, 2000) occurs in boiling water of a much higher mineral concentration than the “boilover” bubbles of the present invention. Boiling water can precipitate minerals long before the water reaches a high enough mineral concentration to “foam,” but the present invention catches the water at a much earlier stage and pumps it out, starting over with fresh water before mineral precipitate can occur.  
       Conclusion, Ramifications and Scope  
       [0027]    Accordingly, the reader will see that the humidifier of this invention can be used to provide steam for humidification as well as for commercial, industrial and medical uses with a minimum of maintenance required. The advantages contributing to the low-maintenance feature of this humidifier include the following:  
         [0028]    it provides a heating chamber that keeps the heated water in rapid motion, thereby limiting the precipitation of minerals onto internal parts;  
         [0029]    it provides a heating chamber that produces steam quicker than prior-art humidifiers;  
         [0030]    it permits the purging of the humidifier tank quickly and without the use of a drain valve;  
         [0031]    it permits the purging of the humidifier tank without sending boiling hot water down the drain (which can harm some pipes); and  
         [0032]    it permits the detection of undesirable mineral concentration in the boiling water.  
         [0033]    Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example, the humidifier can have other shapes besides concentric or parallel cylinders. The humidifier may be made out of metal, plastic, or any suitable material. The humidifier may be molded, and/or made in pieces and assembled using glue, threaded joints, o-rings, or any suitable fastening system The humidifier may be made in many sizes to produce varying quantities of steam, and the steam generated may be intended for other uses besides humidification. The hardware of this invention can be controlled by any suitable control system, be it electro-mechanical, electronic, or microprocessor-based. Thus, the scope of this invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.