Patent Publication Number: US-8523562-B2

Title: Kilns for processing ceramics and methods for using such kilns

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 11/280,953, filed Nov. 16, 2005, which claims priority to U.S. Provisional Application No. 60/628,693, filed Nov. 17, 2004, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention is directed generally toward kilns for processing ceramics and, more particularly, to portable kilns for use in the home environment. 
     BACKGROUND 
     Kilns can be used to harden, burn, and/or dry a number of different materials. In one common application, for example, kilns are used in the production of ceramics. This process, generally referred to as “firing,” can include chemically refining clay objects by heating them until a crystalline matrix of silica and alumina forms, thus making the resulting ceramic articles hard and durable. Depending on the size, complexity, and desired finish of the ceramic articles, this process can take a significant amount of time. 
     To fire a ceramic workpiece in a kiln, the temperature of an internal processing chamber is raised to a relatively high temperature (e.g., over 1800° F.), maintained at that temperature for a given period of time to adequately heat the clay object until the clay develops the desired properties, and then cooled relatively quickly so that the ceramic workpiece can be retrieved from the processing chamber and the kiln can be used to process another workpiece. Because of the high temperatures involved, conventional kilns typically include relatively thick insulating sidewalls and extensive cooling systems. As a result, these kilns are large and cumbersome, relatively expensive, and generally unsuitable for home or personal use. Moreover, the exterior surfaces of such kilns can still become relatively hot during operation, thus making the kilns undesirable for in-home or personal use. 
     SUMMARY 
     The following summary is provided for the benefit of the reader only and does not limit the invention. Aspects of the invention are directed generally to portable kilns or other types of kilns for processing ceramics. A kiln configured in accordance with one embodiment of the invention includes an inner body configured to hold one or more ceramic workpieces for processing. The kiln can also include an outer body at least partially surrounding the inner body and spaced apart from the inner body to define an airflow passageway therebetween. The airflow passageway includes an inlet proximate to an upper portion of the outer body and an outlet proximate to a lower portion of the outer body. The kiln can further include an air mover positioned to move air through the airflow passageway from the inlet toward the outlet. In several embodiments, the kiln can additionally include a lid assembly pivotably coupled to the outer body and configured to sealably close against at least the inner body. 
     A kiln configured in accordance with another embodiment of the invention includes an inner body configured to hold one or more ceramic workpieces for processing, and an outer body spaced apart from the inner body to define an airflow passageway therebetween. The airflow passageway includes an inlet proximate to an upper portion of the outer body and an outlet proximate to a lower portion of the outer body. The kiln can also include a lid assembly operably coupled to the outer body and configured to sealably close against at least the inner body. The kiln can further include a radiant barrier positioned in the airflow passageway between the inner body and the outer body, and a fan positioned proximate to the lower portion of the outer body. The fan is positioned to move air through the airflow passageway from the inlet toward the outlet to cool the inner body during processing of the ceramic workpieces. 
     A method for processing ceramics in accordance with a further aspect of the invention includes placing a ceramic workpiece into a processing chamber of a kiln and increasing the temperature in the processing chamber to process the ceramic workpiece. The method can also include flowing air from an inlet positioned proximate to an upper portion of the kiln through a passageway extending at least partially around the processing chamber to maintain the temperature of an exterior portion of the kiln at or below a preset temperature. In several embodiments, the method can further include reflecting at least a portion of the heat generated by the processing chamber back toward the inner body using a radiant barrier positioned in the airflow passageway. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are isometric views of a kiln configured in accordance with an embodiment of the invention. 
         FIG. 2  is an isometric cross-sectional view of the kiln of  FIGS. 1A and 1B . 
         FIG. 3A  is an enlarged, side cross-sectional view taken from the area  3 A of  FIG. 2  illustrating several aspects of the invention. 
         FIG. 3B  is an enlarged, side cross-sectional view taken from the area  3 B of  FIG. 2  illustrating other aspects of the invention. 
         FIG. 3C  is an enlarged, side cross-sectional view taken from the area  3 C of  FIG. 2  illustrating further aspects of the invention. 
         FIG. 3D  is an enlarged, isometric view taken from the area  3 D of  FIG. 1B  illustrating yet another aspect of the invention. 
         FIG. 4A  is a side view and  FIG. 4B  is a bottom isometric view of the kiln of  FIGS. 1A-3D  and a kiln transport assembly configured in accordance with an embodiment of the invention. 
         FIG. 5  is a side cross-sectional view of the kiln of  FIGS. 1A-3D  illustrating various aspects of several embodiments for cooling the kiln during operation. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes various aspects of kilns and other heating devices for processing ceramics, glazes, and/or other related materials. Certain details are set forth in the following description and in  FIGS. 1A-5  to provide a thorough understanding of various embodiments of the invention. Well-known structures, systems and methods often associated with kilns and related systems, however, have not been shown or described in detail below to avoid unnecessarily obscuring the description of the various embodiments of the invention. Any dimensions, angles, and other specifications shown in the Figures are merely illustrative of particular embodiments of the invention. Accordingly, other embodiments of the invention can have other dimensions, angles, and specifications without departing from the spirit or scope of the present disclosure. In addition, those of ordinary skill in the relevant art will understand that additional embodiments of the invention may be practiced without several of the details described below. 
       FIGS. 1A and 1B  are isometric views of a kiln  100  configured in accordance with an embodiment of the invention. Referring to  FIG. 1A , the kiln  100  can include an inner body  110  configured to hold one or more ceramic workpieces (not shown), and an outer body  120  at least partially surrounding the inner body  110 . The outer body  120  is spaced apart from the inner body  110  to define an airflow passageway  130  therebetween. The kiln  100  can further include a lid assembly  140  pivotably coupled to the outer body  120 . The lid assembly  140  can be configured to sealably close against the inner body  110  and, in at least several embodiments, the outer body  120 . In  FIG. 1A , the lid assembly  140  is illustrated in an open position to provide access to a processing chamber  114 . In  FIG. 1B  the lid assembly  140  is sealably closed against the inner body  110  and at least a portion of the outer body  120  for workpiece processing. 
     Referring to  FIGS. 1A and 1B  together, the kiln  100  includes an air inlet  132  in the lid assembly  140  and an air outlet  134  in the outer body  120 . The inlet  132  and outlet  134  are in fluid communication with the airflow passageway  130  ( FIG. 1A ). As described in detail below with reference to  FIG. 2 , the kiln  100  further includes an air mover configured to move ambient air through the airflow passageway  130  from the inlet  132  toward the outlet  134  to maintain the surface temperature of the outer body  120  at or below a preset temperature during operation of the kiln  100 . For example, in one embodiment, the surface temperature of the outer body  120  can remain cool to the touch, while the processing chamber  114  is heated to over 1800° F. for workpiece processing. Various features of several embodiments of the system for cooling the inner body  110  are described in greater detail below with reference to  FIGS. 2-5 . 
       FIG. 2  is an isometric cross-sectional view of the kiln  100  of  FIGS. 1A and 1B . The inner body  110  includes an inner wall  112  defining the processing chamber  114  for ceramic workpieces (not shown). The inner body  110  further includes an outer wall  116  that faces the outer body  120 . The inner body  110  can include a refractory material that is configured to withstand the high temperatures necessary to process the ceramic workpiece and the drastic changes in temperature throughout the processing cycle. The thickness of the inner body  110  (i.e., the distance between the inner wall  112  and the outer wall  116 ) can vary depending on the desired operational parameters for the kiln  100  and/or the material used to form the inner body  110 . 
     The lid assembly  140  further includes an inner body lid portion  146  configured to releasably engage or otherwise mate with the inner body  110  to sealably close the processing chamber  114 . In the illustrated embodiment, the inner body lid portion  146 , can include a first chamfered portion  147  configured to mate with a second chamfered portion  117  of the inner body  110  to seal the processing chamber  114  when the lid assembly  140  is closed (as illustrated in  FIG. 2 ). One advantage of the relatively large surface area of the interface between the sidewall of the inner body  110  and the inner body lid portion  146  is that the chamfered interface can minimize heat loss from the processing chamber  114  during operation as compared with processing chambers that include non-chamfered interfaces. In a further aspect of this embodiment, the inner body lid portion  146  carried by the lid assembly  140  can be slightly adjustable (e.g., it can “float” or move horizontally and/or vertically) relative to the lid assembly  140  and the inner body  110 , thereby allowing the first chamfered interface portion  147  of the inner body lid portion  146  to more accurately and tightly seat against the second chamfered interface portion  117  of the inner body  110 . 
     In another aspect of this embodiment, the kiln  100  includes a first radiant barrier  160  positioned in the airflow passageway  130  between the inner body  110  and the outer body  120 , and a second radiant barrier  168  carried by the lid assembly  140 . The first radiant barrier  160  can include a first side  162  facing the outer wall  116  of the inner body  110  and a second side  164  facing the outer body  120 . The first radiant barrier  160  defines (a) a first portion  136  of the airflow passageway  130  between the inner body  110  and the first side  162  of the first radiant barrier  160 , and (b) a second portion  138  of the airflow passageway  130  between the second side  164  of the first radiant barrier  160  and the outer body  120 . Further details regarding the first and second portions  136  and  138  of the airflow passageway  130  are described below with respect to  FIG. 5 . The second radiant barrier  168  is spaced apart from the inner body lid portion  146 . 
     In one embodiment, the first side  162  of the first radiant barrier  160  and the lower side of the second radiant barrier  168  facing the inner body lid portion  146  can each include a polished, highly reflective surface. One advantage of this feature is that the reflective surface can help maintain the temperature of the outer body  120  at an acceptable level by reflecting heat from the inner body  110  back toward the inner body during kiln operation. The first radiant barrier  160  can also include a plurality of fins  166  projecting from the first side  162  of the first radiant barrier  160  toward the outer wall  116  of the inner body  110 . The fins  166  are positioned to create an area of low pressure within the first portion  136  of the airflow passageway  130  to help increase the flow of air within this portion of the airflow passageway  130 . In other embodiments, the first and second radiant barriers  160  and  168  can include different features and/or have other arrangements depending on a number of different factors including manufacturing cost, operating temperatures, etc. 
     As mentioned previously, the kiln  100  includes an air mover  170  (e.g., a fan) positioned to move air through the airflow passageway  130  from the inlet  132  toward the outlet  134 . In the embodiment illustrated in  FIG. 2 , the air mover  170  is located proximate to a lower portion of the kiln  100  in communication with the airflow passageway  130 . In other embodiments, however, the air mover  170  can be positioned at different locations and/or have different configurations. In several embodiments, the kiln  100  can further include a battery  182  operably coupled to the air mover  170  and/or other kiln systems (not shown). The battery  182  is configured to power the air mover  170  and various controls of the kiln  100  in the event of an external power failure while the kiln  100  is processing the ceramic workpiece. In this regard, the battery  182  is a back-up feature that allows the air mover  170  to continue cooling the inner body  110  and maintain the outer body  120  at or below a preset temperature until processing is complete. 
     In still another aspect of this embodiment, the kiln  100  can include a debris screen  180  positioned proximate to the inlet  132  of the airflow passageway  130 . The debris screen  180  includes a number of apertures configured to allow air to pass, but prevents large particulates or other undesirable materials from entering the airflow passageway  130 . In other embodiments, the debris screen  180  may have a different configuration or be positioned at a different location. In still other embodiments, the debris screen  180  can be omitted. 
       FIG. 3A  is an enlarged, side cross-sectional view taken from the area  3 A of  FIG. 2  illustrating several aspects of the invention. As this view illustrates, the first radiant barrier  160  includes an upper edge portion  310 , and the second radiant barrier  168  includes a lower edge portion  312  spaced apart from the upper edge portion  310  to define an offset  314  between the two structures. The offset  314  is configured to cause additional ambient air to flow into the first portion  136  of the airflow passageway  130  to further cool the inner body  110  during kiln operation. In other embodiments, the offset  314  can have a different arrangement and/or dimension or be omitted. 
       FIG. 3B  is an enlarged, side cross-sectional view taken from the area  3 B of  FIG. 2  illustrating another aspect of the invention. In this embodiment, the kiln  100  includes a latch assembly  320  configured to releasably secure the lid assembly  140  in a closed position during processing. The latch assembly  320  can include, for example, a solenoid mechanism  322  to toggle a pin  324  between an unlocked position (shown in broken lines) and a locked position (shown in solid lines). In the locked position, the pin  324  engages a catch  326  to restrain the lid assembly  140  in a closed position. The latch assembly  320  can be operably coupled to a controller (not shown) that causes the pin  324  to remain in the locked position while the kiln  100  is operational (e.g., when the temperature in the processing chamber  114  is above a preset temperature, such as 130° F.). In other embodiments, the latch assembly  320  can have a different configuration (e.g., the latch assembly may have a generally vertical orientation rather than the generally horizontal orientation in the illustrated embodiment) and/or the latch assembly  320  may include different features. 
       FIG. 3C  is an enlarged, side cross-sectional view taken from the area  3 C of  FIG. 2  illustrating one method for attaching the inner body  110  to the first radiant barrier  160 . In the illustrated embodiment, the inner body  110  includes a plurality of protrusions or dimples  330  (only one is shown) projecting away from the outer wall  116  of the inner body  110  toward the first side  162  of the first radiant barrier  160 . A plurality of spacers  332  (only one is shown) can be engaged with corresponding protrusions  330  to releasably attach the inner body  110  to the first radiant barrier  160 . Each spacer  332  can include, for example, a generally cylindrical riser portion  336  at least partially surrounding the corresponding protrusion  330  and an engagement feature  334  configured to mate with or otherwise engage the protrusion  330 . The riser portion  336  can be formed from a material that generally prevents thermal transfer between the inner body  110  and the first radiant barrier  160 . The riser portion  336  can be releasably secured to the first radiant barrier  160  with a fastener  338 . An advantage of this feature is that the spacer  332  is configured to allow some minor relative movement between the inner body  110  and the first radiant barrier  160  during processing, while preventing thermal transfer between the two structures. 
       FIG. 3D  is an enlarged isometric view taken from the area  3 D of  FIG. 1B  illustrating still another aspect of the invention. As this view illustrates, the lid assembly  140  can include a user interface  340  for controlling operation of the kiln  100 . The user interface  340  can include, for example, a power button  342  to power the kiln  100  on and off and one or more selector buttons  344  (two are shown in  FIG. 1B  as  344   a  and  344   b ) to activate various functions of the kiln  100 , such as starting/canceling the glazing process and unlocking the lid assembly  140 . The user interface  340  further includes a display  346  to provide feedback to the user regarding the current operational status of the kiln  100 , such as temperature, time, etc. In other embodiments, the user interface  340  can include different features and/or the features may have a different arrangement. 
       FIG. 4A  is a side view and  FIG. 4B  is a bottom isometric view of the kiln of  FIGS. 1A-3D  and a kiln transport assembly  360  configured in accordance with an embodiment of the invention. Referring to  FIGS. 4A and 4B  together, the kiln  100  includes an interface portion  350  configured to releasably receive a portion of the kiln transport assembly  360 . In the illustrated embodiment, for example, the kiln transport assembly  360  is a hand truck with engagement members  362  received within the interface portion  350  of the kiln, a vertical frame  364  with one or more handles at an upper portion of the frame  364 , and a set of wheels  366 . Using the kiln transport assembly  360 , a user (not shown) can readily move the kiln  100  from one location to another location either before or after processing. Compared with the large and relatively cumbersome conventional kilns described previously, the kiln  100  can be relatively easy to move from one location to another. Additionally, during normal operation of the kiln  100 , the kiln transport assembly  360  can be disengaged from the kiln  100  and stored separately. In other embodiments, the kiln  100  may include one or more sets of wheels attached to the outer body  120  in addition to (or in lieu of) the wheels  366  of the kiln transport assembly  360 . In still further embodiments, the kiln  100  can include a permanent or at least partially permanent transport assembly rather than the removable kiln transport assembly  360  described above. 
       FIG. 5  is a side cross-sectional view of the kiln  100  of  FIGS. 1A-3D  illustrating various functional aspects of the kiln during operation. In the illustrated embodiment, the air mover  170  is configured to move ambient air (as shown by the arrows A) through the airflow passageway  130  from the inlet  132  toward the outlet  134 . More specifically, after passing through the inlet  132 , the air flow A moves into both the first portion  136  and the second portion  138  of the airflow passageway  130 . The first portion  136  of the airflow passageway  130  is closer in proximity to the inner body  110  than the second portion  138  and, therefore, the first portion  136  of the airflow passageway  130  is generally at a higher temperature than the second portion  138  of the airflow passageway. The air flow A passing through the first portion  136  is accordingly heated to a higher temperature than the air flow A passing through the second portion  138  of the airflow passageway. 
     In one aspect of this embodiment, the offset  314  (discussed in detail above with respect to  FIG. 3A ) is configured to increase or supplement the flow of cooler ambient air into the first portion  136  of the airflow passageway  130  to help cool the inner body  110 . In another aspect of this embodiment, the kiln  100  can further include a plurality of supplemental air intake portions  410  in the outer body  120  and generally aligned with a lower portion of the inner body  110 . The air intake portions  410  are in fluid communication with the airflow passageway  130 . In operation, an additional volume of cooler ambient air can flow through the air intake portions  410  into the airflow passageway  130  and mix with the exhaust air passing out of the first and second portions  136  and  138  of the airflow passageway  130  and toward the air mover  170 . In this way, the air flow A is cooled before being exhausted from the outlet portions  134 . 
     One feature of at least some of the embodiments of the kiln  100  described above with respect to  FIGS. 1A-5  is that the outer body  120  of the kiln  100  is kept relatively cool during operation. One advantage of this feature is that the kiln  100  can be used in a variety of environments (e.g., home or personal use) where higher temperatures would be undesirable. In contrast, as discussed above, the exterior surfaces of conventional kilns can become relatively hot during operation and, accordingly, such kilns are generally unsuitable for home use. 
     Another feature of at least some of the embodiments of the kiln  100  described above is that the kiln is portable and relatively small as compared with conventional kilns. For example, the kiln transport assembly  360  can be used to move the kiln  100  from a first location to a second location with relative ease. Still another feature of at least some embodiments of the kiln  100  is the relatively small size of the kiln as compared with conventional kilns. An advantage of these features is that it can reduce the time and cost associated with the production and processing of ceramic articles because a user can perform the firing processes at home using the kiln  100 , rather than having to take the ceramic articles to be processed in a commercial-grade kiln. 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the invention. For example, the kiln can include a different number of air movers and/or the air movers may be positioned at different locations within the kiln. Additionally, in several embodiments the kiln  100  can be configured to process glass, jewelry, and/or other related materials in addition to (or in lieu of) ceramic materials. Aspects of the invention described in the context of particular embodiments may be combined or eliminated in other embodiments. Further, while advantages associated with certain embodiments of the invention have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.