Electric resistance heating devices – Heating devices – Vaporizer
Reexamination Certificate
2000-04-20
2001-08-14
Walberg, Teresa (Department: 3742)
Electric resistance heating devices
Heating devices
Vaporizer
C261S142000
Reexamination Certificate
active
06275652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention relates to humidifiers for generating steam, and more particularly relates to heating elements used in such humidifiers.
2. Brief Description of the Related Art
Humidifiers are commonly used in residential and commercial settings to increase the level of humidity in the air for various purposes, such as health, safety and reliability. For instance, it has been found that increased humidity reduces the amount of recuperation time required for upper respiratory infections. In addition, increased humidity reduces the amount of static charge which can build up on electrostatic sensitive devices, such as semiconductors and integrated circuits.
After operating a humidifier for a period of time, the components of the humidifier must typically be cleaned in order to control bacterial growth and remove mineral deposits. Mineral deposits caused by excess minerals in solution, such as calcium in the water used to generate steam is a problem, particularly when the deposits form on a heating element used to bring the water to a boiling point.
FIGS. 1A and B
show a top and side view, respectively, of a heating element of the prior art. This conventional heating element includes a mounting portion
15
and a ring
11
having an open interior section
13
. The heating element is suspended in water within a boiling chamber of the humidifier. It has been found that the inner circumference of the ring
11
is particularly susceptible to the deposition of minerals, which in some cases causes a so-called “arch effect” wherein the deposited minerals create arches across the open interior section
13
of the ring
11
. These arches are particularly difficult to remove by the user, and removal often mars the external finish of the heating element such that additional minerals are deposited more quickly and are even more difficult to remove.
Some of the conventional heating elements include a flattened bottom surface, which becomes a collection point for small air bubbles that are created along a lower surface of the boiling chamber and float upwards as the water is boiled. As the smaller bubbles combine to form larger bubbles under the flattened bottom surface of the heating element, these larger bubbles eventually escape and float to the top of the boiling chamber creating an undesirable noise to the user upon bursting at the top of the boiling chamber. In addition, as the larger air bubbles burst, water droplets are projected onto additional surfaces surrounding the boiling chamber. These droplets leave additional mineral deposits or scaling upon evaporating.
Still other heating elements have a horizontally disposed lower portion that transfers excessive heat from the heating element to the remaining components of the humidifier. Since in most cases much of the remaining components are either plastic or not suitable for operating at high temperatures, this creates an undesirable and often dangerous situation. In addition, the proximity between the horizontally disposed portion and the mounting portion of the heating element provides restricted cavities which are prone to mineral deposits.
Therefore, it would be advantageous if a heating element could reduce the amount of mineral deposits on and around the heating element and/or reduce the noise created by air bubbles which collect underneath the heating element.
SUMMARY OF THE INVENTION
A humidifying apparatus formed in accordance with the present invention includes a housing, a tray for holding water and a heating element. The heating element is at least partially disposed within the tray and includes a mounting portion, a leg portion and a foot portion. The mounting portion is coupled to the housing and an upper end of the leg portion of the heating element. The leg portion extends substantially vertically downward from the mounting portion into the tray. The foot portion is coupled to a lower end of the leg portion and extends substantially horizontally therefrom.
The leg portion is elongated and separates the mounting portion and the foot portion, which reduces mineral deposition on the heating element. The foot portion is shaped such that a line from the upper surface to the lower surface must pass across a perimeter of the heating element when viewed from above. The bottom surface of the foot portion is preferably convex, partially spherical or curved upward from a nadir to the perimeter of the heating element.
The humidifying apparatus formed in accordance with the present invention can also include a gasket disposed around a cylindrical portion of the heating element located above a flange on the heating element. The gasket provides a seal between the heating element and the housing when the heating element is affixed thereto. The gasket includes an upper annular ring, a central annular ring, a lower annular ring and a side cross-sectional profile. The central annular ring is coupled to the upper annular ring and has a perimeter which is less than the perimeter of the upper annular ring. The lower annular ring is coupled to the central annular ring and has a perimeter which is about the same as the perimeter of the upper annular ring. Each of the annular rings have an inner circumference which is substantially the same, and defines a vertical conduit of substantially constant diameter extending through the gasket.
The heating element is disposed within the conduit of the gasket, and the annular rings are coupled such that the perimeter of the annular rings are substantially concentric when viewed from above. A side cross-sectional profile of the gasket substantially conforms to a side cross-sectional profile of the housing surrounding the heating element. A heating element having the features described above is also provided in accordance with the present invention.
A preferred form of the heating element and a humidifier including the heating element of the present invention, as well as other embodiments, objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
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Fastovsky Leonid
Hoffmann & Baron , LLP
Marino Francis E.
The Holmes Group, Inc.
Walberg Teresa
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