Abstract:
A roaster and method for roasting utilizing a tangential flow reducing structure which directs and guides airflow from a blower device into a roasting vessel with minimal swirl and circular flow. The tangential flow reducing structure is preferably one or more baffles, and is preferably located within a plenum in the base of the roaster. More preferably, the roaster has a number of substantially vertical baffles channeling airflow into a vertical and reduced-swirl flow entering the roasting vessel. The roaster also preferably has a unique connection between the roasting vessel and a base upon which the roasting vessel rests, with a flat washer-shaped gasket maintaining a fluid tight seal between the roasting vessel and the base. To tighten the seal, the roaster also preferably includes a cover which is pivotably attached to a support structure supporting the cover in position over the roasting vessel when the roasting vessel is on top of the base. When the cover is in position covering the open top of the roasting vessel, it preferably exerts a light compressive force upon the roasting vessel, which in turn exerts a compressive force upon the gasket to create a better seal between the roasting vessel and the base. Preferably, both the roasting vessel and the roaster base have screens to prevent debris, coffee bean hulls, and other foreign matter from falling into the base. Also, the roaster is preferably provided with a chaff receptacle connected to the cover to collect such matter.

Description:
FIELD OF THE INVENTION 
     The present invention relates to roasters, and more specifically, to apparatuses and methods for roasting coffee beans in a roasting vessel with primarily axial intake air flow. 
     BACKGROUND OF THE INVENTION 
     Over the past several decades, a number of advancements in the art of roasting coffee beans, nuts, and the like have taken place. For example, the introduction of relatively small kitchen-sized coffee bean roasters was a significant development in the art, permitting the roasting process to be performed at home rather than in a store or restaurant. As another example, it is now recognized that faster and better roasting is made possible through “fluidizing” during the roasting process. In other words, better results are achieved when the food items being roasted are circulated via air flow within a vessel (i.e., when such items are “fluidized”) while being roasted. 
     Roasting food matter by fluidizing the food is, of course, limited to food matter which is in the form of a plurality of relatively small items. For example, roasters which fluidize an amount of food during the roasting process are commonly used to roast coffee beans, nuts, and the like. Therefore, although the remainder of this disclosure makes reference only to roasting coffee beans in a coffee bean roaster, it should be noted that the present invention can be used for roasting any food item in the form of multiple parts capable of being fluidized. 
     An important feature of most coffee bean roasters utilizing a fluidized bean roasting method is the manner in which the beans flow or are circulated within the roasting vessel. Each fluidizing design attempts, with mixed success, to achieve uniform bean circulation while keeping as many beans as possible floating within the roasting vessel. Notwithstanding the existence of several roaster designs in which coffee beans are fluidized during roasting, however, a roaster capable of fully fluidizing a charge of coffee beans with minimal air flow force and roasting beans in a uniform manner remains a somewhat elusive goal. 
     Another problem with conventional coffee bean roasters regards the connection commonly existing between the coffee bean roasting vessel (in which the coffee beans are placed and are contained during the roasting process) and the connected apparatus emitting the hot air flow for roasting coffee beans within the vessel. Typically, this connection is preferably relatively fluid tight so as to ensure adequate internal pressure between the connected apparatus and the coffee bean roasting vessel. A fluid tight connection helps to prevent pressure loss through the connection and reduces the chance of coffee beans, hulls, debris, etc. from exiting the roaster between the roasting vessel and the connected apparatus. The connection is also preferably designed to prevent coffee beans, hulls, and/or debris from falling from the coffee bean roasting vessel into the connected apparatus for those roaster designs in which the vessel rests atop an air emitting base or housing. 
     Many prior art coffee bean roasters have a permanently secured roasting vessel within the roaster and therefore do not have sealing arrangements which permit user insertion and removal of the roasting vessel. In those conventional coffee bean roasters which do have a removable roasting vessel, a fluid-tight seal between the vessel and the base or housing is typically created via an annular seal or bead surrounding a bottom portion of the roasting vessel or by a compression and gasket mechanism. The annular seal or bead arrangement is subject to wear with repeated insertion and removal of the roasting vessel, and depends heavily upon a precise fit between the roasting vessel and the base or housing. Compression and gasket mechanisms commonly used for removable roasting vessels are relatively complex and therefore are expensive to manufacture. As such, conventional sealing arrangements are generally less than optimal. 
     Also, conventional connection designs often either do not adequately protect against beans, hulls, or debris from falling into the apparatus connected to the roasting vessel, do so at the expense of a connection which is either difficult and expensive to manufacture or is hard to clean, or do not protect against waste and dust escaped during roasting from re-entering the roaster. Despite the large number of roaster designs which attempt to establish a sufficient vessel-to-base/housing seal and to prevent matter from falling or being drawn via air intake into the base or housing connected to the roasting vessel, a simple, fully effective, reliable and easy to clean connection between the roasting vessel and the base or housing has not been introduced. 
     In light of the problems and limitations of the prior art described above, a need exists for a coffee bean roaster in which improved airflow ensures better coffee bean roasting results, which utilizes a reliable and easily cleaned and manufactured seal between the roasting vessel and its base or housing, and which protects components (such as a fan, heater, and motor) within the base or housing from debris falling or being drawn into the base or housing or being drawn into the base or housing via air intake. Each preferred embodiment of the present invention achieves one or more of these results. 
     SUMMARY OF THE INVENTION 
     In the present invention, improved coffee bean roasting results are obtained by establishing a substantially axial and preferably vertical airflow into the roasting vessel creating fountain-like vessel flow. Unlike numerous prior art devices which either permit or attempt to generate an angled, swirl, or whirlwind flow of air into the roasting vessel to fluidize the bed of coffee beans therein, the present invention includes at least one element located upstream of the roasting vessel to prevent such flow. Preferably, the element is a series of baffle members located and oriented in such a manner as to guide air from the base or housing of the roaster into the roasting vessel in a substantially vertical direction (i.e., parallel to the axis of the roasting vessel) with reduced or no flow tangential to the vessel axis. Without the baffle members to guide the airflow into the roasting vessel in this way, the airflow into the roasting vessel is swirled or has a whirlwind effect generated by the fan or other conventional blower device in the roaster. By guiding the air via baffles or other flow guiding element as described above, airflow into the roasting vessel is preferably made uniform and has minimal swirl and tangential flow. The inventors have found that such flow into the roasting vessel produces unique coffee bean flow inside the roasting vessel and a uniform and improved coffee bean roasting effect. 
     In one preferred embodiment of the present invention, a plurality of baffles are secured in place between the roasting vessel and the roaster fan. The plurality of baffles are preferably arranged in a star shaped configuration and are each vertically oriented to define a series of vertical channels through which the air flows just prior to entering the roasting vessel. However, grid or other baffle patterns can also be used depending upon ease of manufacture, assembly, and other factors. In another preferred embodiment, two or more levels of such baffles are positioned one vertically above the other, with the levels of baffles most preferably being misaligned with respect to one another (e.g., in a star-shaped baffle arrangement, the arms of the star on each level are axially rotated with respect to the arms of the stars on other levels). Multiple baffle levels can be used to further remove swirl or whirlwind flow from the air forced by the fan prior to entry into the roasting vessel. In yet another embodiment, a flow plate secured between the roasting vessel and the roaster fan has a series of apertures therethrough which guide air into the roasting vessel with minimal to no swirl or whirlwind flow. The flow plate is preferably of a thickness substantial enough to prevent flow which is tangential to the axis of the vessel from entering the roasting vessel. However, to accomplish this same result, the flow plate can instead have a number of tubes extending from its surface and into the roasting vessel. Depending at least in part upon the design of the roaster fan and the direction of airflow generated thereby, a plenum plate can be located between the fan and the baffles, flow plate, tubes, or other flow control element. Airflow generated by the fan is preferably passed around the plenum plate and through or beside the baffles, flow plate, tubes, or other flow control element. 
     The present invention also preferably utilizes a unique connection arrangement between the roasting vessel and the base or housing from which air is heated and forced into the roasting vessel. In particular, a flat substantially washer-shaped gasket is preferably used to create a fluid-tight seal between the roasting vessel and the base or housing. When installed in the roaster, the open bottom end of the roasting vessel rests atop the gasket. The lip of the open bottom preferably rests upon the gasket, which itself is sealed to the base or housing to create the fluid-tight seal. The roaster is preferably provided with a top and a cover pivotably mounted to the top. When the cover is pivoted over the top of the roasting vessel and secured into place by a retaining member (such as a spring clip or lever), the cover exerts a light compressive force upon the roasting vessel which acts to better seal the open bottom end of the roasting vessel to the gasket, thereby ensuring a tight and reliable seal for the roaster. This preferred design not only requires much simpler and less expensive elements than prior art roasters, but also provides a connection which is more reliable and easier to clean. 
     In addition to the better sealing connection just discussed, the roasting vessel-to-base connection of the present invention is designed to prevent debris such as coffee bean fragments, hulls, etc. from entering the base or housing to which the roasting vessel is connected. Because the base and roasting vessel both have openings which are adjacent and through which air is forced and guided in a substantially vertical direction in the roasting process, it is desirable to minimize the number and impact of obstructions within the air flow path. The present invention therefore preferably has a screen covering the open bottom of the roasting vessel and a screen covering the opening in the base or housing. Although two screens are preferred, other embodiments of the present invention have only one of the two screens described. The use of a dual screen in the connection between the roasting vessel and the base or housing ensures that less debris enters the base or housing. 
     Many food types generate a significant amount of dust, chaff, or other particulate waste which is difficult to contain or filter. To protect against such matter re-entering the roaster through the roaster air intake hole(s), the roaster is preferably provided with an air intake filter covering the intake holes or otherwise located on the roaster to filter such matter from air entering the roaster. 
     The coffee bean roaster of the present invention can also have a filter in fluid communication with the inside of the roasting vessel via the cover of the roaster. Air and entrained chaff, dust, hulls, and debris from roasting preferably passes from the roasting vessel and into the filter located in a chaff receptacle connected to the roasting vessel. 
     More information and a better understanding of the present invention can be achieved by reference to the following drawings and detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is further described with reference to the accompanying drawings, which show preferred embodiments of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in embodiments which are still within the spirit and scope of the present invention. 
     In the drawings, wherein like reference numerals indicate like parts: 
     FIG. 1 is a perspective view of the coffee bean roaster according to a first preferred embodiment of the present invention, showing the cover of the roaster closed; 
     FIG. 2 is a perspective view of the coffee bean roaster of FIG. 1, showing the cover of the roaster open; 
     FIG. 3 is an exploded perspective view of the coffee bean roaster shown in FIGS. 1 and 2; 
     FIG. 4 is an elevational view of the coffee bean roaster shown in FIGS.  1 - 3  with the roaster cover closed, taken along section  3 — 3  of FIG. 1; 
     FIG. 5 is an elevational view of the coffee bean roaster shown in FIGS.  1 - 4  with the roaster cover open, taken along section  4 — 4  of FIG. 2; 
     FIG. 6 is an detailed elevational view of the base top of the coffee bean roaster shown in FIGS.  1 - 5 ; 
     FIG. 7 is an alternate embodiment of the base top shown in FIG. 6; 
     FIG. 8 is yet another alternate embodiment of the base top shown in FIG. 6; 
     FIG. 9 is a perspective view of the baffles of the coffee bean roaster shown in FIGS.  1 - 8 ; 
     FIG. 10 is an exploded perspective view of the baffles according to a second preferred embodiment of the present invention; 
     FIG. 11 is a perspective view of a first type of flow plate according to the present invention; and 
     FIG. 12 is a perspective view of a second type of flow plate according to the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The coffee bean roaster of the present invention (indicated generally at  2 ) preferably has a top  10 , a base  12 , and a roasting vessel  14 . The top  10  preferably includes a chaff receptacle housing  16  and a cover  18 , while the base  12  preferably has a housing  20  within which air is heated and blown upwards into the roasting vessel  14  to cook a charge of coffee beans placed within the roasting vessel  14 . 
     A motor  22  (powered by electricity from a wall outlet via a standard cord and plug assembly, battery, etc.) is preferably secured within the housing  20  and is connected to a fan  24  in a conventional manner. Preferably, the motor  22  is secured to a bottom  26  of the roaster  2  via conventional fasteners (not shown). To secure the fan  24  within the housing  20 , the fan  24  can have a fan housing  28  also secured to the bottom  26  of the roaster  2  via conventional fasteners. It will be appreciated by one having ordinary skill in the art that the above-described manner in which the motor  22 , fan  24 , and fan housing  28  (if used) are secured within the housing  20  is presented herein only by way of example, and that several other well-known configurations and securement methods are possible and fall within the scope of the present invention. 
     To better contain and direct air from the fan  24  to the roasting vessel  14 , the base  12  of the roaster  2  is preferably provided with a plenum housing  30  which extends from around the fan  24  to a position at the top of the base  12 . Where a fan housing  28  is used, the plenum housing  30  is attached in a conventional fashion thereto to enclose the fan  24  from behind to a position downstream of the fan  24 . Alternatively, the fan housing  28  and the plenum housing  30  can be a single unit within which the fan  24  is enclosed on the sides and rear. As is best seen in FIG. 6, the plenum housing  30  defines a plenum  32 —an enclosure open at the top and enclosing the fan  24 , heating element  34 , and baffles  36  as is further described below. When the fan  24  is turned by the motor  22 , the plenum housing  30  acts to contain and direct the airflow generated by the fan  24  toward the base opening  38  and into the open bottom of the roasting vessel  14  to fluidize thc coffee beans therein. Therefore, it is desirable that the plenum housing  30  and fan housing  28  are sealed against the passage of fluid (e.g., air) through anything but the base opening  38 . Further, the plenum  32  preferably does not include any portions extending around sides of the roasting vessel  14  to reduce localized and unnecessary heating of lower portions of the roasting vessel  14 . 
     To roast the coffee beans within the roasting vessel  14 , the airflow generated by the fan  24  is heated by a heating element  34  within the plenum  32  prior to passing through the base opening  38 . The heating element  34  is preferably a conventional electrical resistance element (such as a coil heater or plate heater) which is secured within the plenum  32  a distance above the fan  24 . The heating element  34  can be secured a distance from the fan  24  in a number of manners well-known to those skilled in the art, such as by resting upon pins or a ledge extending inwardly from the plenum housing  30 , by being suspended from supports which are themselves attached to the top of the plenum housing  30  or are part of the plenum housing  30 , etc. However, in one preferred embodiment of the present invention illustrated in the figures, the heating element  34  is secured via conventional fasteners (not shown) atop a support ring  42  which itself is secured about its outer circumference between the plenum housing  30  and the fan housing  28 . Preferably, the same fasteners used to secure the plenum housing  30  to the fan housing  28  also secure therebetween the support ring  42 . To elevate the heating element  34  above the fan  24 , the support ring  42  preferably has an inverted dish shape (without the dish center) as shown in FIGS.  3 - 6 . 
     To ensure a fluid-tight seal between the fan housing  28 , the support ring  42  and the plenum housing  30 , it is preferred (although not required) to install housing gaskets  40  between the fan housing  28  and the support ring  42  and between the support ring  42  and the plenum housing  30 . The housing gaskets  40  and their material of manufacture are conventional in nature. 
     The airflow generated by the fan  24  is inherently highly turbulent in nature, having swirls and whirlwinds throughout. If left uncontrolled, such flow is typically transmitted from the fan  24 , downstream through the base opening  38 , and into the roasting vessel  14 . The swirling airflow pins certain portions of some beans against the high-temperature side of a roasting vessel, overheating such portions and creating an inhomogeneous roast. To control this flow, one embodiment of the present invention utilizes a number of baffles  36  which are preferably vertically oriented. As the airflow from the fan  24  passes the baffles  36 , the airflow is vertically channeled and directed, and the components of airflow which are tangential to the axis of the roasting vessel  14  are reduced or eliminated. This type of structure acts not only to direct the flow in a uniform manner, but also removes a large amount of turbulence such as swirling and whirlwind effects from the airflow. Airflow exiting the baffles  36  and entering the roasting vessel  14  therefore is more uniform and controlled to impart a controlled airflow force upon coffee beans within the roasting vessel  14 . This results in a unique and improved ability to circulate and roast coffee beans within the roasting vessel  14 . 
     As shown in FIG. 9, the baffles  36  are preferably arranged in a star shape, each being connected at the center of the star shape to define a series of channels  44  through which the airflow passes. The baffles  36  can be a number of plates secured such as by welding, riveting, etc. to one another at one end, or can instead be a series of longer plates notched at their centers to fit one within the other to arrive at the same star-shaped arrangement. It will be appreciated by one having ordinary skill in the art that the baffles  36  can be secured to one another in a large number of ways to produce the same or a similar baffle structure as illustrated in FIG.  9 . It will also be appreciated that the baffles  36  can take any number of shapes (oval, circular, triangular, etc.) beyond the generally rectangular shapes illustrated in FIG. 9, and that the number of baffles  36  making up the baffle structure can vary from a very large number to as few as one. In this regard, the baffle structure and the number of baffles  36  employed in the baffle structure depend heavily upon a number of factors such as flow speed, the distance from the fan  24  to the baffles  36 , and baffle size and shape. Another variable which is dependent upon these factors is the width of the baffles  36 . In general, longer channels  44  can result in more uniform and controlled flow exiting the channels  44  and entering the roasting vessel  14 . Therefore, a balance must be achieved between the desired maximum height of the roaster  2  and the baffle width. 
     Other preferred embodiments of the present invention utilize different baffle structure arrangements. For example, rather than use the star shaped baffle arrangement as illustrated in FIG. 9, the baffles  36  can instead be arranged in a grid form if desired. 
     In an alternate embodiment of the present invention illustrated in FIG. 10, multiple baffle levels are used to better control the airflow to the roasting vessel  14 . Each baffle structure is substantially the same as the baffle structure illustrated in FIG.  9 . One baffle structure is axially aligned with and preferably abuts the second baffle structure. Also preferably, the baffles  136  of each baffle structure are misaligned with respect to one another. In other words, the channels  144  defined by the baffles  136  are not continuous through the first and second baffle structures, but are broken by the relative angular misalignment of the baffles  136  in each baffle structure. Such misalignment acts to further lower spiral and whirlwind flow entering the roasting vessel  14 . Although the baffle structures shown in FIG. 10 are both star shaped, it should be noted that mixed baffle structure types (e.g., one star shaped and one grid shaped) can also be employed. Also, even more levels of baffles  136  can be used within the roaster  2 . 
     The baffles  36 ,  136 , can be secured within the plenum  32  in a number of manners well-known to those skilled in the art. For example, the baffles  36 ,  136  can be secured via conventional fasteners, welding, etc. to the plenum housing  30 , or can even be formed as a part thereof, can rest upon pins or ledges which extend from the plenum housing  30 , or can be fastened via conventional fasteners directly to the heating element  34  to be supported thereby. In the preferred embodiment of the present invention as illustrated in FIGS.  4 - 8 , the baffles  36  are preferably supported upon the heating element  34  via a cross-support  46 . The cross support  46  engages holes in the heating element  34  and has notches which mate snugly onto the baffles  36 , thereby supporting the baffles  36  in raised relationship over the heating element  34 . 
     It should be noted that in order to practice the invention, the baffles  36 ,  136  need not be used in conjunction with a plenum housing  30 , or even with a base  12  such as that shown in FIGS.  1 - 8 . An important aspect of the present invention rests in the use of baffles  36 ,  136  to create a substantially vertical airflow into the roasting vessel  14  for the unique and improved roasting vessel flow described herein. Optional additional features include particular housing or base structures and manners of supporting the baffles  36 ,  136 . 
     A number of elements and structures which are alternatives to baffles  36 ,  136  can be used to direct flow in a substantially vertical direction and to reduce or minimize flow tangential to the axis of the roasting vessel  14 . Another such flow control element is shown in FIG.  11 . The flow plate  84  has a number of apertures  86  therethrough through which air flows from the base  12  of the roaster  2  to the roasting vessel  14 . The apertures  86  can be arranged in any pattern across the surface of the flow plate  84 . To reduce or minimize tangential, whirlwind, and circular flow into the roasting vessel  14 , the flow plate  84  is of sufficient thickness to guide and direct airflow passing through the apertures  86 . The size of the apertures  86  also impacts the effectiveness of the apertures  86  to reduce tangential, whirlwind, and circular flow. Therefore, the ratio of plate thickness to aperture diameter is preferably selected such that the plate thickness is approximately the same as the aperture diameter (thereby obstructing or hindering flow from passing through the flow plate  84  unaffected at an angle to the flow plate  84  of approximately 0-45 degrees). More preferably, the plate is thicker and/or the aperture diameters are smaller to obstruct or hinder such flow within 0-60 degrees of the plate surface, and most preferably, the plate is thicker and/or the aperture diameters are smaller to obstruct or hinder such flow within  080  degrees of the plate surface. 
     Yet another alternative to the baffles  36 ,  136  of the preferred embodiment of the present invention is illustrated in FIG.  12 . The flow plate  88  illustrated in FIG. 12, like the flow plate  86  in FIG. 11, has a number of apertures  90  therethrough through which air flows from the base  12  of the roaster  2  to the roasting vessel  14 . Also as with the flow plate  86  in FIG. 11, the apertures  90  can be arranged in any pattern across the surface of the flow plate  88 . Extending from each aperture  88  is a tubular element  92  which acts in much the same manner as the elongated apertures  86  of the flow plate  86  in FIG.  11 . Specifically, the relative diameters and lengths of the apertures  88  and tubular elements  92  impact the effectiveness of these elements to reduce tangential, whirlwind, and circular flow. Therefore, the ratios discussed above with respect to the flow plate  86  of FIG. 11 apply in the same manner as the flow plate  88  in FIG.  12 . Flow plate  88  has the advantage of producing similar results as flow plate  84 , but with significant material and weight savings for the roaster  2 . 
     It will be appreciated by one having ordinary skill in the art that a number of other flow control elements and structures can be used to reduce or remove whirlwind, circular, or tangential flow from airflow entering the roasting vessel  14 . For example, a plurality of side-by-side tubular elements (similar to tubular elements  92 ) can be attached together to form a bank of tubes through which airflow is passed to reduce or remove tangential, circular, and whirlwind flow. Such other elements and structures fall within the spirit and scope of the present invention. 
     As noted above, there exist several ways in which the baffles  36 ,  136  can be secured or supported within the roaster  2 . Of course, the shape and size of the alternative flow control elements and structures just described will (at least in part) affect the attachment and/or support designs for such flow control elements and structures. Also, it may be necessary in some roaster designs to add elements and structure for guiding airflow from the fan  24  to the baffles,  36 ,  136 , flow plate  84 ,  88 , etc. For example, where the fan  24  is of a type which produces primarily radial flow, airflow from the fan  24  is preferably directed upward along the walls of the plenum housing  30  to the flow control elements or structure (e.g., baffles, flow control plate, and the like). In such a case, a plenum plate (not shown) can be located between the heating element  34  and the flow control elements or structure, and airflow from the fan  24  preferably passes radially around the plenum plate to the flow control elements or structure. Because airflow therefore enters the flow control elements or structure from radially outward positions, baffles  36 ,  136  are preferably employed as the flow control elements. Baffles  36 ,  136  are also the preferred flow control elements where the heating element  34  is of a coil type sandwiched between two plates and over which the baffles  36 ,  136  are located. In both cases, airflow does not or cannot pass from the fan directly upward to the flow control elements or structure, but instead passes around an element to reach the flow control elements or structure. The baffles  36 ,  136  can accept radial flow, and are therefore preferred flow control elements in such roaster designs. 
     In order to protect the internal elements within the base  12  from foreign objects and debris, it is highly preferred to secure a base screen  48  made from a heat-resistive material such as metal, composite fiber, etc. over the base opening  38  in a conventional fashion (e.g., via welding, gluing, molding, etc.). The screen  48  is preferably a wire mesh fine enough to catch foreign objects such as coffee bean hulls and bean fragments, but coarse enough to avoid significantly obstructing the flow of air from the baffles  36 ,  136 . Most preferably, a wire mesh having holes ranging in size from 0.08 cm to 0.64 cm is used. 
     The roasting vessel  14  preferably rests atop the plenum housing  30  and has a substantially open bottom end  50  which is adjacent to the base opening  38  when the roasting vessel  14  is placed upon the base  12 . A washer gasket  52  is preferably used to establish and maintain a seal between the roasting vessel  14  and the base  12 . The washer gasket  52  is flat and annular in shape, and has a central aperture large enough to not present an obstruction to airflow from the base opening  38  to the open bottom end  50  of the roasting vessel  14 . As best shown in FIG. 6, the washer gasket  52  is preferably sandwiched between the plenum housing  30  and the lower edge  54  of the open bottom end  50  of the roasting vessel  14  to establish a fluid-tight seal between these elements. The washer gasket  52  is preferably secured to the top of the plenum housing  30  in a conventional manner, such as by gluing with a high-temperature adhesive, by riveting, by snap-fitting the gasket  52  within a groove or grooves in the top of the plenum housing  30 , etc. 
     The preferred base shape is not limited to the shape illustrated in the figures, and can instead be somewhat different. With reference to FIG. 7, the base  212  can have a top  213  which extends over the top  215  of the plenum housing  230 , in which case another washer-shaped gasket  253  can be sandwiched between the plenum housing  230  and the inwardly-extending top  213  of the base  212  to establish a fluid-tight seal between these elements. For this alternate arrangement, the washer gasket  252  is preferably secured to the top of the base  212  rather than to the top  215  of the plenum housing  230 , and the open bottom end  250  of the roasting vessel  214  rests upon the washer gasket  252 . 
     In yet another preferred embodiment illustrated in FIG. 8, the base  312  has a top  313  which extends over the top  315  of the plenum housing  330 , and the washer gasket  352  is sandwiched between the plenum housing  230  and the inwardly-extending top  313  of the base  312  to establish a fluid-tight seal between these elements. In this case, the roasting vessel  314  rests upon the washer gasket  352  which extends in a radially inward direction beyond the plenum housing  330  and the base  312 . For additional support of the washer gasket  352 , the washer gasket  352  can also rest upon the base screen  348  (described below). 
     The roasting vessel  14  can take a number of shapes other than the preferred generally round cylindrical shape illustrated in FIGS.  1 - 8  (e.g., oval, square, rectangular, etc.). Also, the narrowed lower section of the roasting vessel  14  shown best in FIGS. 4 and 5 can be eliminated if desired, but is preferred to permit better circulation of the fluidized beans within the roasting vessel  14  and to afford a larger-sized upper vessel volume. The roasting vessel  14  is preferably made of a transparent and heat resistive material such as glass, heat treated glass, or high temperature clear plastic. Of course, other materials such as aluminum, steel, composites, ceramics and other refractory materials can instead be used where a transparent roasting vessel  14  is not required. 
     By virtue of the flow entering the base opening  38  of the roaster vessel  14  in a substantially upward manner with minimal flow tangential to the axis of the roaster vessel  14  and with minimal whirlwind and swirl flow, airflow and coffee beans travel substantially up the center of the roaster vessel  14  and near to the top of the roaster vessel  14 . The air and coffee beans then preferably travel radially outward and fall along the walls of the roaster vessel  14 . The restriction shape near the bottom of the roaster vessel  14  creates an area of low pressure near the restriction which helps to guide the falling beans along the periphery of the roaster vessel interior. 
     The resulting flow within the roaster vessel  14  is therefore fountain-like as shown in FIG. 4, with the bed of fluidized beans traveling up the center of the roaster vessel  14  and down the sides of the roaster vessel  14 , with minimal to no swirl about the axis of the roaster vessel  14 , and with upward and downward flow substantially parallel to the axis of the roaster vessel  14 . For best flow results, the velocity of the air generated by the fan  24  is sufficient to push the fluidized coffee beans to an upper region of the roaster vessel  14 , but not strong enough to push the coffee beans to the cover  18 . Flow velocity is preferably selectable by a user via conventional roaster controls or is programmed into automatic roaster controls, both control types preferably controlling fan speed and power to the fan. It should be noted that although the above-described flow is preferred, it is also possible to reverse the flow so that airflow and coffee beans enter around the periphery of open bottom end  50  of the roaster vessel  14 , travel upward along the walls of the roaster vessel  14 , and then fall down the center of the roaster vessel  14  to be recirculated into the upward flow. This alternate flow type can be created by blocking airflow from the base  12  in the center of the base opening  38  and/or in the center of the open bottom end  50  of the roaster vessel  14 . For example, a plate or other circular-shaped element can cover a central portion of the base screen  48  and/or a central portion of the vessel screen  56  (described below) to block or reduce central flow into the roaster vessel  14 . 
     To prevent debris and foreign material from exiting through the substantially open bottom end  50  of the roasting vessel  14 , it is highly preferred to secure thereover in a conventional manner (e.g., via welding, gluing, molding, etc.) a vessel screen  56 . Like the base screen  48 , the vessel screen  56  is preferably a heat-resistive wire mesh fine enough to catch foreign objects such as coffee bean hulls and bean fragments, but coarse enough to avoid obstructing the flow of air from the base  12 . Most preferably, a wire mesh having holes ranging in size from 0.08 cm to 0.64 cm is used. The combined filtering abilities of the vessel screen  56  and the base screen  48  ensure a high degree of protection against matter entering the base  12  before, during, and after the roasting process. 
     The roasting vessel  14  also preferably has a handle  58  attached thereto for grasping the roasting vessel  14 . In the preferred embodiment of the roasting vessel  14  illustrated in FIGS.  1 - 5 , the handle  58  is connected to the roasting vessel  14  at a lower end via a band  60  attached to the handle  58  by a conventional fastener  61  (such as a screw, rivet, spot weld, etc.) and secured about the lower end of the roasting vessel  14 . The band  60  can also be used to hold or help hold the vessel screen  56  to the roasting vessel  14  as shown in FIGS. 4 and 5. Specifically, parts of the vessel screen  56  can be wrapped around the lower edge  54  of the roasting vessel  14  and be clamped between the band  60  and the bottom outside wall of the roasting vessel  14 . The handle  58  is preferably connected to the upper end of the roasting vessel  14  via conventional fastening devices and methods, and can even be connected with a second band much the same as the band  60  described above. One having ordinary skill in the art will appreciate that several different fastening devices and methods can be used to attach the handle  58  to the roasting vessel  14 . Examples of such devices and methods include clips extending from the handle  58  over the upper and/or lower lips of the roasting vessel  14  (see FIGS.  1 - 5  showing the upper end of the handle  58  secured in this manner), fastener(s) passing through the wall of the roasting vessel  14 , high-temperature adhesive, etc. The handle  58  can even be made an integral part of the roasting vessel  14  such as by molding or casting, in which case it is preferred to cover the handle with an insulating material if the roasting vessel  14  is made from a heat-conductive material. These other fastening devices and methods fall within the spirit and scope of the present invention. 
     Highly preferred embodiments of the present invention include a cover  18  which is pivotable over and away from the substantially open top end  62  of the roasting vessel  14 . The cover  18  keeps contents within the roasting vessel  14  from blowing out of the roaster  2  during roaster operation. As shown in FIGS.  1 - 5 , the cover  18  can also have a number of vent grooves  66  therein for permitting limited airflow between the inside of the cover  18  and the outside of the roaster  2 . Although a particular placement and number of grooves  66  are shown in the figures, it should be noted that the grooves  66  can instead be replaced by one or more holes, slots, or other aperture types in different and/or the same locations in the cover  18 . Any one or more of these apertures can be covered on the inside or outside of the cover  18  by a screen or screens (shown in phantom in FIG.  2 ). For example, the cover can have vent apertures (not shown) permitting air to escape out of the top of the cover. To prevent hulls, chaff, and other debris from also escaping out of the vent apertures, it is preferred that filters, mesh screening, or another like element(s) cover such apertures. The underside of the cover can also include one or more ribs or other projecting or stepped members for retaining the coffee bean hulls in the roasting vessel  14  (not shown). 
     The cover  18  also preferably performs the function of exerting a light compressive force upon the roasting vessel  14  to establish a tighter seal between the roasting vessel  14  and the washer gasket  52  upon which it rests. As best shown in FIGS.  4 - 5 , the cover  18  is preferably mounted for rotation about an upper portion of the roaster top  10 . To achieve the compressive force just mentioned, the height of the roaster top  10  is therefore selected so that when the cover  18  is closed to its position shown in FIGS. 1 and 4, it forces the roasting vessel  14  against the washer gasket  52 . To retain the cover  18  in this position, the roaster  2  is provided with a retaining member  68  preferably located upon the roasting vessel  14 , and most preferably located upon the handle  58  of the roasting vessel  14 . The retaining member  68  can take many forms sufficient to secure and unsecure the cover  18  into its compressed state over the roasting vessel  14 . For example, the retaining member  68  can be a lever  70  biased in the latching position via a latching spring  72  as shown in FIGS.  1 - 5 . The retaining member  68  can instead be a catch operable by the user, a latch of any conventional style, a releasable snap-type seal such as a tight tongue-and-groove arrangement, or any other retention mechanism well known to those skilled in the art. Though not required, the cover  18  can be biased in its open position by a conventional cover spring  74  preferably attached to the cover  18  and/or the roaster top  10 . 
     With particular reference to FIGS.  2 - 5 , it can be seen that the roaster vessel  14  is in fluid communication with the chaff receptacle housing  16  via a vent  76  located beneath the cover  18  when the cover  18  is closed. The vent  76  (which can simply take the form of one or a plurality of slits, holes, or other aperture types which are larger than the vent grooves  66 ) has apertures which are large enough to permit coffee bean hulls and debris to pass therethrough to the chaff receptacle housing  16  but are small enough to prevent coffee beans from doing the same. The vent  76  is preferably part of a support structure  78  extending from just above the base  12  to the cover  18 . At a minimum, the support structure  78  need only be a wall or similar rigid structure sufficient to support the cover  18  above the roasting vessel  14 . Preferably however, the support structure  78  defines the chaff receptacle housing  16  as that shown in FIGS.  1 - 5 . In such case, the support structure  78  has a plurality of apertures  80  (holes, grooves, etc.) permitting air which has flowed into the support structure  78  past the vent  76  to exit from the roaster  2 . 
     To address the problem of dust, chaff, and debris often associated with operation of coffee bean roasters, the roaster  2  of the present invention preferably has a removable chaff receptacle  82  of an appropriate size and shape to fit within the chaff receptacle housing  16 . The chaff receptacle  82  preferably has a plurality of apertures  94  passing through at least one of its surfaces. The apertures  94  are preferably large enough to permit air to flow therethrough, but are small enough to restrict flow of chaff, hulls, and other debris from passing outside of the chaff receptacle  82  and chaff receptacle housing  16 . It will be appreciated by one having ordinary skill in the art that the chaff receptacle  82 , like the chaff receptacle housing  16 , can be of a number of shapes (e.g., box shaped, tubular, spherical, cone-shaped, etc.) and sizes and can be located in a number of areas with respect to the roaster vessel  14  (e.g., beside the roaster vessel  14 , on top of the roaster vessel  14 , etc.). In order to further reduce the escape of dust, chaff, and debris from the chaff receptacle  82  and the chaff receptacle housing  16 , a conventional filter element (not shown) can be placed within the chaff receptacle  82  and/or between the chaff receptacle  82  and the chaff receptacle housing  16 . Where a filter element is used, the filter element preferably at least covers all the holes  80  in the chaff receptacle housing  16 . 
     As best shown in FIG. 3, the cover spring  74  is preferably an upper extended portion of the chaff receptacle  82 . In such case, the cover spring  74  is more preferably made of a resilient material which is able to deflect and exert a spring force upon the cover  18  when the cover  18  is closed. Most preferably, the chaff receptacle  82  and the cover spring  74  are integral to one another and are made of flexible steel. The preferred shape of the cover spring  74  illustrated in FIG. 3 also serves the purpose of guiding airflow and entrained dust, chaff, and debris from the cover  18  into the chaff receptacle housing  16 . 
     The roaster  2  of the present invention preferably has at least one air intake aperture  96  to permit air to be drawn into the base  12  during roasting operations. More specifically, a number of air intake apertures are preferably located in the bottom  26  of the roaster  2 . To reduce the intake of dust, chaff, and debris not only from the environment surrounding the roaster  2  but also from the roaster  2  itself, a conventional filter element (not shown) preferably covers the air intake apertures  96  or at least is located so that substantially all air entering the roaster  2  passes through the filter element. 
     The embodiments described above and illustrated in the figures arc presented by way of example only and arc not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims. 
     For example, the materials making up each element of the coffee bean roaster  2  can be selected from a wide variety of materials. The elements exposed to the greatest heat (such as the elements within the top of the base  12  and particularly within the plenum  32 , the roasting vessel  14 , and the lower portions of the roaster top  10 ) should be made of a heat resistant material such as metal, high-temperature plastic or composite, ceramic, glass, etc. However, the other elements of the roaster  2  can be made from virtually any suitable material (high-temperature or otherwise) such as those just mentioned. One having ordinary skill in the art will recognize that alternative materials for each element of the roaster  2  fall within the spirit and scope of the present invention.