Gas and liquid contact apparatus – Contact devices – Porous sheet
Reexamination Certificate
1999-01-08
2001-05-29
Simmons, David A. (Department: 1724)
Gas and liquid contact apparatus
Contact devices
Porous sheet
C261SDIG006, C073S029020
Reexamination Certificate
active
06237899
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an evaporative humidifier having a wick change indicator. More particularly, the present invention relates to a wick change indicator that monitors the performance of the wick to assess whether the wick requires replacement.
2. Description of the Prior Art
Humidifiers are useful in raising the humidity of air inside homes, particularly during periods of dry weather during the winter and heat inside a home causes the relative humidity within the home to be lowered to an uncomfortable level. Under these circumstances, it is beneficial to introduce moisture into the air. Several types of humidifiers for increasing humidity in a room are well known in the art, and include steam-type, ultrasonic, warm-air and evaporative humidifiers.
Certain humidifiers, and in particular the evaporative type, generally include a housing having an inlet, an outlet, and a reservoir for holding water, a water absorbing material seated partially submerged in the water of the reservoir, and a fan that is connected to the housing for creating an airflow. The water absorbing material is generally known as a wick in the art and is adapted to draw water in the upper non-emersed part by capillary action. The airflow created by the fan is directed to pass through the upper non-emersed portion of the wick to humidify the air in the room.
A problem associated with humidifiers that utilize wicks is that they tend to accumulate minerals from the water which blocks the capillary action of the wick. Accordingly, the performance of the wick degrades over time requiring replacement.
It is difficult to determine when a wick requires replacement by physical inspection or by monitoring the period of actual use. This is because both of these methods do not assess the actual performance of the wick. The wick will change color as a result of the absorption of various minerals over a period of a time. Since the minerals that exist in public water supplies vary from one municipality to another, practical replacement guidelines based only on a physical inspection and monitoring the length of use are not practical.
Commonly assigned U.S. Pat. No. 5,800,741 to Glenn et al. discloses an evaporative humidifier having a wick filter with color change indicator. The wick change indicator disclosed therein was premised upon a color change indicator that would change color after a period of use. As noted in the specification at Column 9, Lines 45-53, although the life of the wick filter is estimated to be approximately 6 weeks, the water supply can have an adverse effect on the color change indicator disclosed therein.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a humidifier with a wick change indicator.
It is a further object of the present invention to provide a wick change indicator that monitors the performance of the wick to assess whether the wick requires replacement.
It is another object of the present invention to provide a wick change indicator wherein the performance of the wick change indicator is not affected by the mineral content in the water supply.
It is yet another object of the present invention to provide a wick change indicator that is inexpensive and easy to manufacture.
In accordance with one form of the present invention, a humidifier includes a housing having an air inlet, an air outlet, and a reservoir for holding water. The reservoir supports a wick which is seated therein. A fan is provided within the housing for creating an airflow. The airflow enters the air inlet, passes through the wick for adding moisture to the air and exits through the air outlet. The exiting air has an exit-relative humidity associated therewith. A wick change indicator is also provided. The wick change indicator includes a hygrometer positioned within the airflow for measuring the exit-relative humidity of the airflow and a display coupled to the hygrometer for indicating when the wick requires replacement based upon the measured exit-relative humidity reaching a predetermined value. Preferably the predetermined value is approximately 87 percent.
In a preferred embodiment of the present invention, the hygrometer has a humidity sensitive element which is coupled to an indicating needle providing a visual display that the wick requires replacement. Preferably the humidity sensitive element is a metallic coil. The hygrometer may include a support plate with the display formed thereon. The display includes markings such that the needle is positioned with respect to the markings to provide an indication that the wick needs replacement. In an alternative embodiment the metallic coil has a tapered width that decreases from a central end to an external end of the coil for increased accuracy.
In another embodiment of the present invention, the hygrometer is provided as a chemically impregnated label. The label changes color as a function of humidity. The label has a first region that is light in color and darkens when the exit-relative humidity of the airflow reaches a first predetermined value. The label also has a second region that is light in color and darkens when the exit-relative humidity of the airflow reaches a second predetermined value. Either the first region or the second region define a set of indicia to form the display. Preferably the first predetermined value is approximately 87 percent and the second predetermined value is approximately 60 percent.
In yet another embodiment of the present invention, the hygrometer is provided in the form of an electrical-type hygrometer, e.g. a resistive or capacitive element whose value varies as a function of sensed humidity. The display is a liquid crystal type which is mounted to the housing and is calibrated to indicate that the wick requires replacement when the exit-relative humidity of the airflow falls below a predetermined humidity.
In still a further embodiment of the present invention, the wick change indicator includes a second hygrometer that measures the ambient-relative humidity. The wick change indicator has a means for comparing the exit-relative humidity with the ambient-relative humidity for indicating when the wick requires replacement.
The present invention is also directed to a method of monitoring the performance of a wick in a humidifier to determine replacement, includes the steps of:
(a) measuring the exit-relative humidity of the airflow as the airflow exits through the outlet of the housing; and
(b) providing an indication that the wick requires replacement when the exit-relative humidity falls below a predetermined value.
In the method, the predetermined value is preferably approximately 87 percent.
A preferred form of the humidifier having a wick change indicator of the present invention, as well as other embodiments, objects, features and advantages of this invention will apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
REFERENCES:
patent: 1970301 (1934-08-01), Frankel
patent: 2059846 (1936-11-01), Bulger
patent: 2114105 (1938-04-01), Gerber
patent: 2411041 (1946-11-01), Kahn
patent: 3425388 (1969-02-01), West
patent: 4150571 (1979-04-01), Hayes et al.
patent: 4210278 (1980-07-01), Obler
patent: 4687050 (1987-08-01), Podlipnik
patent: 5285960 (1994-02-01), Zografos
patent: 5309726 (1994-05-01), Asbridge
patent: 5364024 (1994-11-01), Lin
patent: 5800741 (1998-09-01), Glenn et al.
patent: 5971205 (1999-10-01), Michaels et al.
Glenn Neville R.
Offir Yigal
Powers Paul
VannRox Robert S.
Hoffman & Baron LLP
Holmes Products Corp.
Hopkins Robert A.
Marino Francis E.
Simmons David A.
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