Patent Application
20170343219
The invention is directed to an apparatus and method related to optimizing the cooling of knobs on a gas cooktop.
An example of an application for the invention is a domestic kitchen gas cooktop having improved cooling of the knobs used to control gas flow.
Some modern domestic kitchens include a gas cooktop as either a countertop mounted cooktop or as a part of a standalone range.
Some domestic cooktops have one or more control knobs that control the amount of gas that is piped to specific gas burners of the cooktop. Some cooktops have a top sheet that is formed from, for example, a piece of sheet steel. The burners protrude through the top sheet such that the heating flames of the burners exist above the top sheet. In some of these cooktops, primary combustion air is drawn from a space below the top sheet and mixed with gas before being ignited. In some cases, the primary combustion air enters the space below the top sheet through holes in the top sheet that exist around shafts of the control knobs.
In some domestic cooktops, the proximity of a control knob to a burner can result in the temperature of the control knob rising above an ideal level.
Applicants recognized this problem and developed a solution as described herein. Applicants also recognized that a control knob that is relatively close to an active burner can be heated by the air drawn through the hole in the top sheet because that air is heated by the burner.
The invention achieves the benefit of routing primary combustion air past one or more gas control knobs to cool the control knobs. The invention achieves this benefit by providing different size control knob passageways through the top sheet. The passageways can be the holes in the top sheet through which the control knob shafts extend. In some embodiments only one passageway has a size that is different from the other passageways. In other embodiments two or more passageways have a different size.
For the comfort of the appliance user, a knob cooling strategy can be very beneficial. In addition, there are government regulatory limits on control knob temperatures under specified operating conditions.
Embodiments of the invention are based on the inventors' recognition that regulating the amount of air allowed to flow around each of the control knobs and through the top sheet can positively influence cooling of a particular control knob. This regulation of the air flow can include regulation of air flow around a gas control knob that is closest to a particular burner and/or regulation of air flow around a gas control knob that controls a particular burner. In particular embodiments, air flow around any gas control knob in the off position would be prevented altogether or limited to a greater extent than air flow around any gas control knob in an on position or vice versa where there is an advantage to utilize cool air that may be around the knob to cool the knob when the burner is on.
Several methods can be employed to provide the above described air flow control. There are active solutions and passive solutions. Examples of active solutions include a cam activated bezel around the knob or the knob shaft that opens in an on position of the control knob and closes in the off position of the control knob. Other examples of active solutions take advantage of the often-present feature of the control knob being in different vertical positions depending on whether the control knob is in an on position or the off position. In these examples, a damper, for example a disk, can be attached to the valve shaft of the control knob such that it moves vertically with the control knob and opens or closes an opening as a result of that movement. Other embodiments use a solenoid valve triggered by the rotation of the gas control knob or a signal from the ignition switch to control the air flow in the on or off position.
Passive solutions include providing holes of different sizes around the different control knob shafts. If one control knob tends to be hotter than others, providing a different size hole around the shaft of the hotter control knob can provide more cooling air flow and therefore a cooler control knob.
In determining the optimal air flow for a particular cooktop and/or situation, the turndown ratio (which is the ratio between the highest heat and the lowest heat) must be considered. If total air flow is reduced too far, a low burning flame can be extinguished (or at least negatively affected) by a lack of sufficient air flow.
Particular embodiments of the invention are directed to a domestic home gas cooktop having a top sheet; a space below the top sheet; a first passageway through the top sheet; a second passageway through the top sheet; a first gas burner that draws primary combustion air from the space below the top sheet; a first gas control knob that controls an amount of gas that flows to the first gas burner, the first gas control knob protruding through the first passageway; a second gas burner that draws primary combustion air from the space below the top sheet; and a second gas control knob that controls an amount of gas that flows to the second gas burner, the second gas control knob protruding through the second passageway. The first passageway and the second passageway have different airflow rates at a given negative air pressure in the space below the top sheet.
Other embodiments of the invention are directed to a method of cooling a gas control knob on a domestic home gas cooktop having a top sheet, a space below the top sheet, a first passageway through the top sheet, a second passageway through the top sheet, a first gas burner that draws primary combustion air from the space below the top sheet, a first gas control knob that controls an amount of gas that flows to the first gas burner, the first gas control knob protruding through the first passageway, a second gas burner that draws primary combustion air from the space below the top sheet, a second gas control knob that controls an amount of gas that flows to the second gas burner, the second gas control knob protruding through the second passageway. The method includes configuring the first passageway differently from the second passageway such that the first passageway and the second passageway have different airflow rates at a given negative air pressure in the space below the top sheet; and causing the first gas control knob and the second gas control knob to be subjected to different cooling as a result of the different airflow rates.
Particular embodiments include the feature of the first passageway being a first hole in the top sheet, and the second passageway being a second hole in the top sheet.
Particular embodiments include the feature of the first hole having a first hole cross-sectional area, the second hole having a second hole cross-sectional area, and the first hole cross-sectional area and the second hole cross-sectional area being different.
Particular embodiments include the feature of the second hole being located farther from the first gas burner than the first hole is located from the first gas burner, and the second hole cross-sectional area being larger than the first hole cross-sectional area.
Particular embodiments include the feature of each of the passageways having a closest burner distance that is defined as a distance between that passageway and the closest one of the burners to that passageway, the closest burner distance of a particular passageway being larger than the closest burner distance of all others of the passageways, and a cross-sectional area of the particular passageway being larger than a cross-sectional area of each other passageway.
Particular embodiments include the feature of a first grommet located in the first hole, the first grommet having an opening having a first grommet cross-sectional area; and a second grommet located in the second hole, the second grommet having an opening having a second grommet cross-sectional area, wherein the first grommet cross-sectional area and the second grommet cross-sectional area are different.
Particular embodiments include the feature of the first hole having a first hole cross-sectional area, the second hole having a second hole cross-sectional area, and the first hole cross-sectional area being equal to the second hole cross-sectional area.
Particular embodiments include the feature of the first gas control knob having a skirt that projects downward from the first gas control knob, the skirt being in a first position that blocks substantially all air from passing through the first hole when the first gas control knob is in a gas off position, and the skirt being in a second position that allows air to pass through the first hole when the first gas control knob is in a gas on position.
Particular embodiments include the feature of the first gas control knob has a shaft and a disk attached to the shaft, the disk being in a first position that blocks substantially all air from passing through the first hole when the first gas control knob is in a gas off position, and the disk being in a second position that allows air to pass through the first hole when the first gas control knob is in a gas on position.
Particular embodiments include the feature of the disk being located below the top sheet and is positionaly fixed relative to a user contact portion of the first gas control knob.
The following figures form part of the present specification and are included to further demonstrate certain aspects of the disclosed features and functions, and should not be used to limit or define the disclosed features and functions. Consequently, a more complete understanding of the exemplary embodiments and further features and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, wherein:
The invention is described herein with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
As explained above, embodiments of the invention provide a solution to the problems associated with elevated temperatures of gas control knobs on a cooktop.
As explained above, the gas control knobs can become heated by their proximity to a burner that is burning gas.
As discussed above, primary combustion air can be provided to the burner from the space below the top sheet. There is often a box-like structure below the top sheet that contains the lower part of the burners, a gas manifold, gas control valves, control wiring, and other parts of the cook top. This box-like structure can be completely or substantially sealed so that little or no combustion air is drawn from the space below the cook top. As a result, all or substantially all of the primary combustion air comes from the area above the top sheet. One of the ways primary combustion air can enter the space below the top sheet is by way of the holes through which the gas control knob shafts extend. This air flow can be used to cool the gas control knobs.
One way to provide cooling of a particular gas control knob is to alter the amount of primary combustion air that is drawn through that control knob's hole in the top sheet. One example of how an embodiment of the invention provides more air flow for a particular control knob is shown in
In some situations, enlarging the hole that is nearest to a particular burner, for example the front right burner in
In some situations, more air flow through a particular hole can actually heat the control knob associated with that hole. For example, if the front right burner in
As a result of these two situations, burner maximum intensity and proximity of the control knobs to the burners must be considered when determining the propper relative size of the holes in the top sheet.
An example of a passive method of controlling cooling air flow is shown in
As can be seen in the above exemplary embodiments, the invention provides solutions to the problems associated with the undesirable heating of gas control knobs on a gas cooktop.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Any of the features described above can be combined with any other feature described above as long as the combined features are not mutually exclusive. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the invention.
