Pyrolytic Cleaning Of Double Ovens

Abstract

A double-oven gas range having a large master oven and a smaller companion oven. Each oven is provided with heating means for raising the temperature of the oven. The master oven has heating means with a capability of reaching and maintaining either a cooking temperature range or a pyrolytic oven-cleaning temperature range. The companion oven has heating means with a capability of reaching and maintaining a cooking temperature range. The master oven has an exhaust vent that empties into a flue duct. The companion oven also has an exhaust vent that empties into the same flue duct. The flue duct has a damper for shunting the exhaust of the master oven into heat-transfer relation with the companion oven either for warming the companion oven, or when the master oven is operating on a pyrolytic oven-cleaning cycle for raising the temperature of the companion oven into the pyrolytic oven-cleaning temperature range for cleaning both ovens at the same time with the same heat source.

Description

BACKGROUND OF THE INVENTION

This invention relates to a pair of domestic ovens that are both capable of undergoing a pyrolytic oven-cleaning cycle. A basic patent in this art is that of Bohdan Hurko, U.S. Pat. No. 3,121,158 which is assigned to the General Electric Company, the assignee of the present invention. A pyrolytic gas oven is also taught in a later patent of Raymond L. Dills and Bohdan Hurko, U.S. Pat. No. 3,364,912, entitled "Self-Cleaning Gas Oven."

The principle object of the present invention is to provide a double-oven appliance with the capability of utilizing the heat of exhaust from one oven as the heat source for the second oven, either for moderate food warming or thawing operations or for a pyrolytic oven-cleaning cycle.

A further object of the present invention is to provide a double-oven gas range with means for recovering a good share of the heat energy from the exhaust of one oven and utilizing this recovered heat for heating the second oven thereby eliminating the need for furnishing a heat exchanger for the first oven to reduce the temperature of its exhaust gases.

A further object of the present invention is to provide a domestic oven having a pyrolytic oven-cleaning capability with means for utilizing the heat energy in the exhaust from this oven within a second oven so that the temperature of the exhaust as it leaves the range will not be excessive.

SUMMARY OF THE INVENTION

The present invention, in accordance with one form thereof, relates to a double-oven cooking appliance where the first oven is capable of both normal cooking operations as well as a pyrolytic oven-cleaning operation. The second oven is capable of normal cooking operations from its own heating source. Each oven is provided with an exhaust vent, and there is a flue duct connecting the exhaust vent of the first oven with the exhaust vent of the second oven. Diverter means are provided in the flue duct to close the duct and force the exhaust gases of the first oven into heat transfer relation with the second oven either for warming the second oven by using the heating means of the first oven or for creating a pyrolytic oven-cleaning cycle in the second oven when the first oven is operated in a pyrolytic oven-cleaning cycle.

BRIEF DESCRIPTION OF THE DRAWING

My invention will be better understood from the following description taken in conjunction with the accompanying drawing and its scope will be pointed out in the appended claims.

The single FIGURE of the drawing is a right side elevational view of a double-oven gas range having a lower master oven with a cooktop carried on its top portion and an eye-level companion oven spaced above the cooktop, with some parts broken away and others in cross section to show the general nature of the construction of the range.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to a consideration of the drawing, there is shown a double-oven gas range 10 for use in a residential kitchen. This range includes three main elements; namely, a waist-high cooktop 11 supported on the top of a lower master oven 12, as well as there being a second or companion oven 13 arranged at eye level above the cooktop. The general designation for this type of range is a 30-inch, double-oven, free-standing range, but this invention is not limited to such a vertical arrangement of the ovens. Another modification would be to incorporate the invention in a double, built-in wall oven combination, either above and below, or side by side. If the companion oven were not arranged at eye level, but were located beside the master oven 12 then the overall range width would probably be a 40-inch width under ordinary conditions. Of course, these three range elements 11, 12 and 13 are assembled within an outer cabinet or body structure 15 which is a supporting superstructure provided with an appearance finish such as porcelain enamel or the like that is available in a variety of colors to match the decor of the modern kitchen. The cooktop 11 is of recessed design, as is generally conventional in this art, such that the surface burners of the cooktop are not visible in this side view. Moreover, the controls for the surface burners and the two ovens 12 and 13 are not shown, since they may be standard controls and do not constitute part of the present invention.

The lower master oven 12 has an oven cooking cavity 17 formed by a boxlike oven liner 19 and a front opening access door 20. The oven door 20 is hinged along its bottom edge as at 21, and it has an elongated door handle 22 arranged adjacent the top edge of the door. The oven liner 19 has a bottom wall (not shown), a top wall 25, a rear wall 26, opposite sidewalls 27, 27 and an open front that is adapted to be closed by the oven door 20.

Actually, the nature of the construction of both the lower master oven 12 and the upper companion oven 13 is generally taught in the before-mentioned patent of Raymond L. Dills and Bohdan Hurko, U.S. Pat. No. 3,364,912 which is assigned to the General Electric Company, the assignee of the present invention. Thus, only a brief explanation will be given of the operational details of each oven as reference may be made to the above-cited patent by anyone wanting the complete details of the oven operation.

There is also a door latch mechanism 30, depicted by a showing of a door latch handle, for locking the oven door 20 closed during a pyrolytic oven cleaning cycle at temperatures above about 550.degree. F. so that entrance may not be gained to the oven cavity when the oven temperatures are above normal cooking temperatures. One example of a satisfactory oven door latch mechanism is taught in the patent of Clarence Getman, U.S. Pat. No. 3,189,375, which is likewise assigned to the assignee of the present invention. As will be well understood by those skilled in this art, a suitable door interlock system would be necessary between the door latch mechanism 30 and the control system for the oven-heating means to preclude the operation of the pyrolytic cycle unless the oven door is first closed and locked, as well to preclude the unlocking of the door until the oven temperature drops back into the normal cooking temperature range. There is a firebox 32 positioned beneath the bottom wall of the oven liner 17, and this firebox contains a gas burner 34 of generally planar construction that is provided with gas flame ports 35 in the opposite side edges thereof. Such a burner would have a rating of about 28,000 B.t.u. which is the equivalent of 8,200 watts of electrical power. At the rear of the burner there is a mixture tube 37 adapted to mix the gas fuel with primary air so as to form a combustible mixture. This mixture tube has a constricted throat or venturi portion 39 and a bell-shaped end 40 that is open to the atmosphere. Telescopically received within this bell-shaped end 40 is a gas supply tube 42 such that the passage of the gas through the venturi portion 39 draws primary air into the rear end of the bell-shaped portion 40. As is conventional in this art, but not shown herein, the gas burner 35 would be provided with an automatic pilot or ignition means and a safety interlock or flame detection system for insuring that the gas supply to the burner 34 will be discontinued in the even the pilot or other ignition system is not functioning properly. Primary air is supplied to the burner 34 through the bell-shaped end 40. The primary air enters the range through the inlet louvers 33 at the backwall of the range cabinet 15. Secondary air enters the firebox 32 through openings 36 in the bottom wall of the firebox. A fan 38 draws the secondary air through louvers 41 and then up through openings 36 for passing around the burner 34 and completing the combustion process.

The oven cavity 17 is provided with an oven vent opening 49 in the top wall 25 of the oven liner, and it is provided with an oxidation unit or smoke eliminator 50 that is positioned over the opening for use during the high-temperature pyrolytic oven-cleaning cycle. This oxidation unit includes a hollow housing 51 supporting a perforated ceramic block of cellular construction such as is sold by the Corning Glass Works under the trade name Cercor. A catalytic coating of platinum or the like covers the cellular surfaces that are exposed to the smoke, odors and vapor that are generated during the degradation of the food soils that became lodged on the walls of the cooking cavity during previous cooking operations thus reducing the temperature and time at which complete oxidation occurs. The surface area of the cells of the ceramic block is large to provide the greatest area of contact between the gases and the catalyst. Hence, at a minimum temperature of approximately 400.degree. F., smoke, odors and other undesirable gaseous products present in the effluent start to undergo an exothermic reaction and increase the rate of temperature rise of the ceramic block above the rated temperature rise of the air and walls of the cooking cavity until the undesirable products have been incinerated. Such a self-heating oxidation unit is described and claimed in U.S. Pat. No. 3,428,435 of Bohdan Hurko and Raymond L. Dills.

The major portion of the flue gases from the oven burner 34 are forced to pass around the outside of the oven liner 19 in the manner of a muffle oven through heating channels 55 which are formed by having the firebox 32 extend up and around the oven liner by use of walls 56 at a spaced distance such that the flue gases generated by the burner 34 pass through the heating channels 55 first in an upward direction toward the front of the oven and then over the top of the oven liner and down the back portion of the sidewalls and then up the rear heating channel into a horizontal flue duct 57 extending from the smoke eliminator 50. The duct 57 empties into a vertical flue duct 47 extending up the rear of the range behind both ovens 12 and 13. Only a fraction of the flue gases are allowed into the oven cavity to insure the heating of the inside of the oven door and to serve as a vehicle for entraining the gaseous degradation products and carrying them through the smoke eliminator. A heavy layer 28 of thermal insulating material surrounds the vertical walls and the top wall 56 of the firebox 32 for retaining the heat of the oven and maintaining moderately low temperatures of the outer surface of the range body 15.

The eye level companion oven 13 is shown formed of a similar construction as the master oven 12, and like parts will be given the same reference numeral except with a prime designation. There is an oven liner 19' and an oven door 23. The door 23 is hinged along a vertical axis 24 arranged at the left side of the oven so that the door swings to the side when opened rather than down as in the lower master oven 12. Of course, this oven door also will have a door lock mechanism to prevent entrance into the oven cavity 17' when the oven temperature is above normal cooking temperatures. There is an oven cavity 17' formed by the oven liner 19' and the oven door 23. A gas burner 34' is positioned in a firebox 32', and there is an exhaust vent 49' provided with a smoke eliminator 50' which returns the flue gases and gaseous degradation products within the oven cavity 17' to the kitchen through an exhaust opening 60 in the top wall of the range. This upper companion oven 13 is also a muffle oven having heating channels 55' formed by the extension of the firebox 32' up around the oven liner 19'. Primary air is furnished to the burner 34' through the louvers 33'. Secondary air enters the firebox 32' through duct 65 in the bottom of the upper oven thereby providing relatively cool ambient air as secondary air for the burner 34' in the event the burner 34' were to be used to supplement the heat of exhaust from the lower burner 34.

Notice at the rear of the upper oven 13 there is a damper 62 adjacent the lower corner which is associated in the vertical flue duct 47 so that in its full line position it allows the exhaust gases from the lower oven 12 to rise up the back of the upper oven 13 and to commingle with the exhaust gases from the upper oven 13 as they are returned to the kitchen atmosphere. This damper 62 may be adjusted to its dotted line position so that it closes the flue duct 47 at the rear of the upper oven 13 such that the exhaust gases from the lower oven 12 are forced to pass through the heating channels 55' around the outside of the oven liner 19' to be in heat-transfer relation therewith such that the heat of the flue gases from the lower oven 12 serves to heat the walls of the upper oven 13. This heating action can serve for moderate food warming or thawing in the eye-level oven 13 or for a pyrolytic oven-cleaning operation in this second oven.

Modifications of this invention will occur to those skilled in this art, therefore it is to be understood that this invention is not limited to the particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit of this invention as claimed.

Claims

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A double-oven range comprising a first relatively large oven and a second smaller oven, the first oven having controlled heating means for raising the temperature within the first oven into a cooking temperature range between about 150.degree. F. and 550.degree. F. as well as into a pyrolytic oven-cleaning temperature range above about 750.degree. F., the second oven having controlled heating means for raising the temperature within the second oven to a cooking temperature range between about 150.degree. F. and 550.degree. F., and first exhaust means provided for the first oven, duct means joining the said exhaust means to the second oven, and a second exhaust means provided for the second oven, whereby the oven heat from the first oven during a pyrolytic oven-cleaning cycle will raise the temperature of the second oven into the pyrolytic oven-cleaning temperature range so that oven soils may be removed from the walls of both ovens by using the heat generated for the first oven.

2. A double-oven range as recited in claim 1 wherein the said second oven is provided with an inner oven liner and an access door forming an oven cooking cavity, the said controlled heating means for the said second oven including gas burner means, and a heating chamber surrounding the oven liner in a spaced relation, the said duct means joining the first exhaust means of the first oven to the heating chamber of the second oven for heating the walls forming the oven cooking cavity of the second oven.

3. A double-oven range as recited in claim 2 wherein the duct means includes a damper for closing the duct means to the heating chamber of the second oven, and bypass duct means associated with the said damper for carrying off the oven heat of exhaust from the first oven.

4. A double-oven gas appliance comprising a first combined cooking and pyrolytic oven and a second cooking oven, the first oven having a first exhaust means, and the second oven having a second exhaust means, and duct means joining the first exhaust means to the second exhaust means such that the exhaust from both ovens are combined, and damper means associated with the duct means for directing the exhaust of the first oven into heat-transfer relation with the second oven when the first oven is operating as a pyrolytic self-cleaning oven for raising the temperature of the second oven into the pyrolytic temperature range above about 750.degree. F.

5. A double-oven gas appliance as recited in claim 4 wherein the second oven is surrounded by a spaced firebox forming heating channels around the second oven in the manner of a muffle oven whereby the said damper means may either open the duct means to the second exhaust means or to the heating channels around the second oven.

6. A double-oven gas range comprising a first, lower master oven and a second, eye-level, companion oven, the first oven having controlled burner means for raising the oven temperature into a cooking temperature range between about 150.degree. F. and 550.degree. F. as well as into a pyrolytic self-cleaning oven temperature range above about 750.degree. F., the second oven having controlled burner means for raising the oven temperature into a cooking temperature range between about 150.degree. F. and 550.degree. F., the first oven having an exhaust vent to carry off combustion gases, the second oven having an exhaust vent to carry off combustion gases, and duct means joining both exhaust vents for carrying off the combustion gases to the exterior of the range, said duct means including a damper located between the two ovens for closing the duct means to the second exhaust vent and opening the duct means to the second oven such that the combustion gases from the first oven will serve to heat up the second oven before the combustion gases exit through the second exhaust vent.

7. A double-oven gas range as recited in claim 6 wherein the second oven is a muffle oven having a boxlike oven liner and an access door forming an oven cooking cavity, heating channels surrounding the walls of the oven liner, the said damper being associated with the said heating channels such that when the damper is moved to close the duct means the combustion gases from the first oven are directed into the heating channels of the second oven for transferring the heat from the gases to the walls of the second oven.

8. A double-oven gas range comprising a first lower oven and a second upper oven, gas burner means for each oven, vent means for each oven, a vertical flue duct rising up the back of the range from the vent means of the lower oven and joined with the vent means of the upper oven to provide a single vent means from the range, and diverter means to close the flue duct behind the upper oven and force the exhaust of the lower oven into heat-transfer relation with the upper oven for raising the temperature of the upper oven, the upper oven having a boxlike oven liner and a front-opening access door forming an oven cooking cavity, heating channels formed around the oven liner, whereby the main portion of the flue gases from the gas burner means of the lower oven pass through the heating channels of the upper oven for heating the walls of the oven cavity into a cooking temperature range between about 150.degree. F. and 550.degree. F. while a minor portion of the flue gases pass through the oven cavity, (A double oven gas range as recited in claim 9) wherein the said gas burner means of the lower oven is capable of raising the temperature of the lower into a cooking temperature range between about 150.degree. F. and 550.degree. F. as well as into a pyrolytic oven-cleaning temperature range above about 750.degree. F., the said diverter means being closed when the lower oven is operating at a pyrolytic oven-cleaning cycle so that the heat of the flue gases of the lower oven will raise the temperature of the walls of the upper oven into a pyrolytic oven temperature of the walls above about 750.degree. F. and both ovens will be cleaned simultaneously.