The present invention relates generally to portable electrical humidifiers, and more specifically to those known as impeller or "cool mist" type humidifiers, which employ a fan, a spinning suction tube, and a diffuser screen. Mist is created mechanically through collision of water dispersed by the spinning tube against the diffuser screen and is exhausted after mixing with air by the fan.
Impeller humidifiers have been known for many years and it is common to employ therewith an overfill protection hole which prevents water poured into a reservoir from rising above a pre-determined maximum. In that way the undesirable wetting of the motor or other electrical components within the humidification unit is avoided. Normally the protective hole is located in a wall of the humidifier tank and vertically positioned at that maximum water level. However, as a result of turbulence created by the spinning suction tube, unintended escape of moisture may occur through the overfill protection hole in the same manner as intended moisture is released at the exhaust opening. Such inadvertently escaping moisture may contact and damage objects such as furniture or wall coverings located behind the humidifier.
one solution to the above described drawback is to attach a tube to the overfill protection hole which depends down from the hole to below the minimum water level of the reservoir. Pressurized 21~1992 air and mist within the reservoir tank are prevented from un-intentional escape at the overfill protection hole by the water within the tank surrounding the tube which water forms a seal.
If the lower end of the tube is below the lowest level achieved during the humidifier's operation, air and mist cannot escape even as the water supply in the reservoir is depleted. However, prior art overfill protection tubes however have had the disadvantages of being an additional component to the humidifier. In addition to the increased costs associated with the manufacture and assembly involved, the protective tubes can be unintentionally removed and lost.
It is the object of the present invention to overcome these drawbacks and provide a humidifier with an improved overfill protection tube.
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:
Fig. 1 is a perspective view of a humidifier in accordance with the present invention;
Fig. 2 is a side view of the humidifier of Fig. l;
Fig. 3 is a front view of the humidifier of Fig. l;
Fig. 4 is a back view of the humidifier of Fig. l;
Fig. 5 is a top view of the humidifier of Fig. l;
Fig. 6 is a bottom view of the humidifier of Fig. l; and Fig. 7 is a sectional view taken on plane A-A of Fig. 5.
A portable humidifier 11 includes a housing 20 that defines a reservoir 12 shown in Fig. 7. The housing 20 is a blow-molded polypropylene tank 21 having a continuous wall thickness of approximately 0.060". As shown, the tank 21 is basically spherical in ~hape, truncated and closed at a bottom wall 22 to provide a stable base and truncated and open at a top portion 23.
An opening 24 in the top portion 23 receives a humidification unit 26 that is supported by a continuous annular shelf 27. A smaller opening 30, concentric with the larger opening 24 provides access into the reservoir 12 for a diffuser screen 31 and suction tube 32 of the humidification unit 26. The opening 30 also functions as a water filling hole for the tank 21. An opening 33 in the upper surface of the housing 20 serves as an exhaust opening through which mist and air are exhausted from the humidifier 11.
The tank 21 also includes an integrally molded overfill protection tube 34 which prevents the water level 35 within the reservoir 12 from rising above a predetermined maximum level 36 when being filled. The top surface 37 of the tube 34 is vertically positioned at the maximum operating level 36 and the bottom surface 21~1g~7 40 of the tube is vertically positioned below a minimum operating level 41 closely adjacent to the tank bottom 22. As the tank is filled, excessive water will result in spillage out of the top 37 of the overfill protection tube and out of the reservoir 12.
This prevented a rise in water level to a height which would result in the wetting of a motor 42 or other electrical parts within the humidification unit 26 when it is positioned on the tank 21. As the water level drops during use of the humidifier 11, air and mist within the tank 21 are prevented from inadvertent escape through the overfill protection tube 34 by the cylindrical wall 43 of the tube which projects down from the tube's top surface 37.
Water within the reservoir 12 and surrounding the cylindrical wall 43 of the tube 34 provides a seal to maintain the air and mist above the water level 35. Since the lower surface of the tube 34 is positioned lower than the minimum water level 41, achieved when the water falls below the lower tip 44 of the suction tube 32, the overfill protection tube 34 is always sealed within the water to prevent air and mist leakage when the humidifier is operating.
The humidification unit 26 includes a partially spherical injection molded plastic cover 46 which also serves as a mounting plate for the motor 42 and a switch 47. Integrally molded and depending from the cover 46 are an outer cylindrical ring 50 and an inner cylindrical housing 51. A lower end of the inner cylindrical housing 51 forms a cylindrical diffuser screen 31 comprised of a continuous series of slots 53 approximately 0.060"
wide adjacent solid separators 54 approximately 0.060" wide. The motor 42 is mounted by screws (not shown) on an underside 55 of the cover 46 and has a shaft 56 directed downwardly therefrom.
Sharing a common axis are the outer cylindrical ring 50, the inner cylindrical housing 51, and the motor shaft 56.
The cover 46 defines an air intake vent 57 consisting of a series of elongated slots 60. Mounted to the cover 46 by screws (not shown) is the control switch 47 whose shaft (not shown) extends upwardly through a hole (not shown) in the cover 46 and is attached to a switch knob 61. The cylindrical outer ring 50 is slightly smaller in diameter than the large hole 29 at the top of the tank 21 to allow for proper radial positioning of the humidification unit 26. When the humidification unit 26 is lowered onto the reservoir 12, a bottom edge 62 of the outer ring 50 contacts an upper surface 63 of the annular shelf 27 to properly position the humidification unit 26 vertically.
Attached to the motor shaft 56 by pressure-fit is an injection molded plastic fan blade 64 consisting of a flat 21519g2 circular disk 65 having a series of radially positioned ridges 66 extending upwardly therefrom. An outer edge 70 of the blade 64 is vertically aligned with and radially spaced from the diffuser screen 31 by approximately 0.125" to 0.25". The combination of the disk 65, the inner cylindrical housing 51, and the cover 46 form an enclosure for the motor 42, switch 47 and electrical wiring 78 therefor. When the blade 64 is rotated by the motor 42, the upwardly extending ridges 66 expel air in a tangential direction through centrifugal force toward the diffuser screen 31. As air is expelled from the blade 64, it is thereby also drawn through the intake openings 57 of the cover 46. The only escape for air drawn into the humidifier 11 is out the exhaust opening 33.
Engaged to the bottom side of the flat disk 65 of the fan blade 64 is the injection molded plastic suction tube 32.
As shown in Fig. 7, the tube 32 consists of an inverted hollow cone 73 defining a conically shaped cavity 81 and having an open top end 74, a first conical portion 75 of approximately sixty inclusive angular degrees, a second conical portion 76 of approximately five inclusive angular degrees, and a truncated apex 77 at its lower tip. The apex 77 of the cone 73 is located below the operating water level in the reservoir 12 and defines a suction intake hole 80 axially positioned at the lowest tip of the tube 32 to allow water to enter the hollow cavity 81.
Energization of the motor 42 results in spinning of the suction tube 32 which draws water in an upward and outward direction by centrifugal force until it reaches a pair of water outlet holes 82 axially spaced one hundred and eighty angular degrees and closely adjacent to the top of the tube 32.
Water that rises within the tube 32 but does not immediately escape through the outlet holes 82 will collect against the fan blade 64 and will be redirected towards and eventually through the outlet holes 82. As the water is dispersed through the outlet holes 82 it sprays against the diffuser screen 31 where it is broken up into a mist. Larger droplets of the mist and water which collects on any other surfaces within the humidifier 11 fall back into the reservoir 12 and will again be drawn into the suction tube 32. Finer droplets of the mist remain airborne and are easily carried by the airflow of the fan through the exhaust opening 33 and out into the environment.
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.