Abstract:
A humidifier includes a base defining an evaporation cavity, a water supply is supported on the base and has a discharge opening communicating with the evaporation cavity and is adapted to maintain a given level of water therein. A humidification unit is removably mounted on the base and includes a heating element projecting into the cavity with a wicking sleeve surrounding the element and into the cavity to wick water therefrom. Energization of the heating element causes evaporation of the water that has been wicked from the cavity. The resulting vapor is discharged through an exhaust grill above the cavity.

Description:
RELATED APPLICATION  
       [0001]    This application is a continuation and formalization of co-pending U.S. Provisional Application S/N 60/237,928, the specification of which is hereby incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates generally to humidifiers and, more specifically, to portable humidifiers intended for domestic use.  
           [0003]    Various types of humidifiers are used to increase the humidity in the home environment. With respect to portable humidifying appliances, they may be broken down broadly into three categories, one being the evaporating type, one being the steaming type, and the last being the misting type. Evaporating type humidifiers typically use belts or pads to increase the rate of evaporation of the water from the liquid to the vapor state. Steaming humidifiers, or vaporizers, generally are used to achieve very high humidification levels by raising the water&#39;s temperature above its boiling point. Misting humidifiers use mechanical means to atomize water into small droplets which are dispersed by a fan. The present invention is most closely related to humidifiers of the steaming and evaporating types.  
           [0004]    Examples of various prior-art steaming humidifiers are disclosed in U.S. Pat. Nos. 5,067,169, 5,131,070, 5,133,044, and 5,143,460. All of these humidifiers are characterized by disclosing humidification means in which a heating element hangs into a water reservoir to cause boiling of the water in the reservoir. This boiling results in vaporization of the water from the reservoir, but characteristically leaves behind the minerals and impurities from the water to collect on the heating element as slag which thereby diminishes the element&#39;s performance and efficiency.  
           [0005]    Examples of various prior art evaporative humidifiers are disclosed in U.S. Pat. Nos. 5,034,162 and 5,108,663. These humidifiers are characterized by disclosing humidification means in which an absorbant and porous pad is placed partially in a water reservoir and partially in an air stream to cause wicking of the water from the reservoir into the airstream. This results in evaporation of the water from the reservoir into the airstream, but is characteristically inefficient as the water and the porous pads are maintained at room temperature. Additionally, the evaporation of water from the pads causes a temperature drop in the exhausting humidified air which is often undesireable in the home environment. The object of this invention, therefore, is to provide an improved portable humidifier for use in domestic applications.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is a portable humidifier including a base defining a water supply cavity; a liquid supply means supported on the base and having a discharge opening communicating with the supply cavity and adapted to maintain a given level of liquid therein; and an humidification unit removably mounted on the base and comprising an electrically energized heater within a porous fabric wicking sleeve projecting into the cavity and adapted to efficiently and rapidly induce warm evaporation of the water, and a vapor passage having a receiving end communicating with the cavity so as to receive vapor therefrom and a discharge end for discharging the vapor received from the cavity into the surrounding environment.  
           [0007]    According to one feature of the invention, the porous fabric wicking sleeve pulls water, including its minerals and impurities, from the cavity by capillary action to the surface of the heating element, where it is rapidly evaporated leaving those impurities and minerals in the sleeve.  
           [0008]    According to another feature, the porous fabric wicking sleeve is easily removable from the heating element. For that reason cleaning of the boiler cavity is simplified and the heating element is kept clean and operating efficiently. The sleeve can easily be removed and regularly washed to remove those impurities and minerals. This feature further also enhances the evaporation efficiency of the unit.  
           [0009]    According to another feature, the heating element preheats the water to increase the rate of evaporation, and the heating element also increases the temperature of the exhausted airstream to overcome the temperture drop otherwise inherent in evaporative humidifiers.  
           [0010]    According to another feature, during normal operation, the wetted wicking sleeve remains at approximately 100 C. degrees, the boiling temperature of water, and the heating element&#39;s surface temperature is thereby regulated. When the supply of water is depleted or the wicking action of the sleeve is reduced, such as by deterioration or excessive residue accumulation, the heating element will realize a sudden increase in surface temperature. A temperature-limiting device in thermal communication with the heating element is thereby triggered to de-energize the heating element and safely disable the humidifier. This same temperature-limiting device also senses the rise in temperature that occurs when the humidification unit is removed from the base and the wick subsequently dries, and thereby serves and a safety shut-off for preventing use of the humidifier when it is not properly assembled. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0011]    These and other objects and features of the invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein:  
         [0012]    [0012]FIG. 1 is a front view of a humidifier in accordance with the preferred embodiment of the invention;  
         [0013]    [0013]FIG. 2 is an exploded perspective view of the humidifier of FIG. 1;  
         [0014]    [0014]FIG. 3 is a left-end view of the humidifier of FIG. 1;  
         [0015]    [0015]FIG. 4 is a right-end view of the humidifier of FIG. 1;  
         [0016]    [0016]FIG. 5 is a top view of the humidifier of FIG. 1;  
         [0017]    [0017]FIG. 6 is a longitudinal cross-sectional view through the humidifier of FIG. 1;  
         [0018]    [0018]FIG. 7 is a transverse cross-sectional view through the humidifier of FIG. 1;  
         [0019]    [0019]FIG. 8 is a rear view of the humidifier of FIG. 1;  
         [0020]    [0020]FIG. 9 is a top view of the base of the humidifier of FIG. 1;  
         [0021]    [0021]FIG. 10 is a wiring diagram of the humidifier of FIG. 1;  
         [0022]    [0022]FIG. 11 is a longitudinal cross-sectional view through a humidifier according to a second embodiment of the invention; and  
         [0023]    [0023]FIG. 12 is a transverse cross-sectional view through the base assembly of a humidifier according to a third embodiment of the invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    A humidifier  100  according to the preferred embodiment of the invention is shown in FIGS.  1  though  10 . A humidification unit  112  and a liquid supply tank  113  are each removably mounted side by side on a base  114 .  
         [0025]    Formed into the upper surface  117  of the base is a reservoir  120  that includes a evaporation cavity  122 . Also included in the reservoir is a liquid supply channel  123  communicating with the evaporation cavity  122  and is an inlet cavity  125  located under the supply tank  113 . A valve actuator stem  126  projects upwardly from within the inlet cavity. Pivotally mounted on the base is a latch member  128  for securing the supply tank  113  to the base.  
         [0026]    The humidification unit  112  includes a horizontal wall  131  within an enclosure  132 . The horizontal wall and side walls  133  of the enclosure cooperate with the evaporation cavity  122  of the base  114  to define an evaporation chamber  135 . Extending downwardly within the chamber from the horizontal wall is a heating element  136  that projects into the evaporation cavity  122  of the base  114 . A porous fibre wicking sleeve  137  surrounds the heating element and is adapted to draw water by capillary action from the evaporation cavity to the surface  139  of the heating element. The sleeve is constructed of an absorbent fabric material such as flame-retardent polyester fiber, which has the ability to wick water from the cavity rapidly, and which is not easily flammable and tolerant to high temperatures. The sleeve is removable from the heating element, which allows physical access to the heating element surface  139  to permit cleaning of the surface and of the sleeve itself An intake grill  141  is disposed low on one of the endure side walls  133  and an exhaust grill  143  closes the upper end of the enclosure. The grills provide vapor communication between the evaporation cavity and the surrounding environment. Retained by the enclosure is electrical control circuitry  151  shown in FIG. 10. A control switch  157  for actuating the electrical control circuit  151  is mounted on the enclosure.  
         [0027]    The liquid supply tank  113  includes a bottom wall portion  162  and an upper portion  163  for storing a supply of water. Closing an opening  161  in the bottom wall portion of the tank is a threaded cap  164  that can be removed to fill the tank with water. The cap includes a valve assembly  166  that projects downwardly into the inlet cavity  125  of the base. The construction of the valve assembly is typical of those of the prior art. When the supply tank  113  is properly positioned on the base  114 , the valve actuator stem  126  of the inlet cavity  125  opens the valve to provide liquid communication between the tank and the inlet cavity. When the tank is not properly positioned on the tank, the valve is closed to prevent inadvertent leakage of water from the tank. The valve is adapted to fill the inlet cavity, and therefore the evaporation cavity  122 , with water to a predetermined water level  167  and to maintain the water at that level until the supply tank empties.  
         [0028]    Operation  
         [0029]    To prepare the humidifier  100  for use, the tank  113  is removed from the base  114  and filled with water through an opening created by removal of the cap  164 . With the cap replaced and the sealed tank inverted and positioned on the base, the valve  166  is opened by the valve actuator stem  126  so that water from the tank flows through the opened valve, through the inlet cavity  125 , through the supply channel  123 , and into the evaporation cavity  122  to submerge the lower portion  169  of the wicking sleeve  137  up to the predetermined water level  167 .  
         [0030]    With the humidifier now turned on by activation of the control switch  157 , the heating element  136  is energized and its surface temperature rises. The aforementioned wicking qualities of the sleeve cause water from the evaporation cavity to rise upwardly and wet the upper portion  171  of the sleeve that surrounds the heating element. Heat from the heating element causes rapid evaporation of the water from this wetted portion of the sleeve, and the drying sleeve thereby draws more water from the evaporation cavity to continually replenish itself.  
         [0031]    The warm vapor evaporating from the sleeve creates an updraft which sucks dry air from the surrounding environment into the chamber through the intake grill  141 . As this air is humidified and heated, it through the exhaust grill  143  and into the surrounding environment. The inherently limiting temperature of the evaporating water from the sleeve causes the surface temperature of the heating element to remain at approximately 100 C. degrees during normal operation.  
         [0032]    As water is depleted from the evaporation cavity  122  by its evaporation from the sleeve, the operating water level is lowered below the predetermined water level  167 . This exposes the valve  166  of the tank  113  and allows air to enter the tank and water to thereby flow from the tank and replenish the water in the evaporation cavity. This continues until the operating level returns to the predetermined level  167  and blocks that air path into the tank to terminate the outflow of water from the tank.  
         [0033]    Once the water in the tank  113  is depleted, the operating water level continues to fall and the wicking by the sleeve  137  is reduced and ultimately terminated. As the upper portion  171  of the sleeve dries, the surface temperature of the heating element rises above the normal operating temperature, which is sensed by temperature-sensor  173 , which thereby opens to terminate energization to the heating element and operation of the humidifier. Similarly, in response to removal of the humidification unit  112  from the base  114 , the sleeve rapidly becomes dry and the heating element temperature rises to open the temperature sensor and de-energize the humidifier.  
         [0034]    Alternatively, various other low-water sensing means from the prior art may be adapted for use in the present invention.  
         [0035]    In the above-described preferred embodiment, the heating element hangs below the water level  167  and into the water in the evaporation cavity, which pre-warms that water and is found to increase the evaporation rate from the upper portion  171  of the sleeve. But in a second embodiment of the invention  200 , shown in FIG. 11, only the lower portion  269  of the sleeve  237  hangs into the water in the evaporation cavity  222 , but the heating element  236  does not hang so low as the water level  267  and therfore does not contact the water.  
         [0036]    In a third embodiment  300 , shown in FIG. 12, the heating element  336  is mounted to the base  314  at the bottom of the evaporation cavity  322  and projects upwardly through the water in the evaporation cavity and into the evaporation chamber  335  above the water level  367 . The sleeve  337  is fitted over the heating element such that a lower portion  369  is submerged into the water. This embodiment humidifies identically, except that in this embodiment, the enclosure  332  over the evaporation cavity is merely a cover with an intake grill  341  and an exhaust grill  343 . Although a similarly affixed temperature sensor  373  is adapted to sense the heating element&#39;s temperature rise when the water supply is depleted, this embodiment lacks means to thermally sense the removal of the enclosure from the base.  
         [0037]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.