Abstract:
A dryer for drying various types of products such as food products and pet food. The dryer includes a frame structure, a conveyor disposed in the dryer, and a heating unit for supplying heat to the dryer. A plurality of relatively lightweight hygienic panels, including doors, is secured to the frame structure and form a part of the exterior of the dryer. The hygienic panels provide access to the interior of the dryer for cleaning and maintenance. Each hygienic panel is sealed so that moisture and air cannot enter the interior of the panel. Disposed inside each hygienic panel is a honeycomb panel and an insulating structure. The hygienic panel provides rigidity and strength to the hygienic panel and at the same time enables the panel to be of a relatively light weight construction.

Description:
FIELD OF THE INVENTION 
     The present invention relates to thermal process system for drying, baking, cooking, and cooling various types of products. More particularly, the present invention relates to a dryer for drying products that includes hygienic or sanitary panels and doors. 
     BACKGROUND 
     Dryers such as the type manufactured and sold by Buhler Aeroglide Corporation are used to dry or thermally treat a wide variety of products, including food products and pet food, for example. These dryers are typically provided with detachable panels and doors that provide access to the interior of the dryer for cleaning and maintenance. One of the shortcomings of dryers of this type is that the removable panels and doors are heavy and do not always meet high hygienic standards. That is, the panels are not sealed and air and moisture can enter the interior of the panels or doors, resulting in the growth of bacteria. 
     Therefore, there has been and continues to be a need for a dryer design that is provided with hygienic or sanitary panels and doors that are sealed and which prevents moisture and air from entering the interior areas of the panels and doors. 
     SUMMARY 
     The present invention is a dryer comprising a frame structure, an interior conveyor or support for receiving and conveying product within the dryer, a heating unit for heating the dryer, and a plurality of hygienic panels, including one or more hygienic doors. Each panel is sealed so as to prevent moisture and air from entering the interior of the panel. In addition, each hygienic panel includes a front, back, and an interior area or space. Mounted in the interior space is a honeycomb panel that provides strength and rigidity to the hygienic panel, and an insulating structure disposed within the interior area of the hygienic panel. 
     In a particular embodiment, the honeycomb structure is secured to the front of the hygienic panel, and there is provided an interior or intermediate panel secured to a side of the honeycomb panel opposite the front of the hygienic panel. Disposed between the interior or intermediate panel and the back of the hygienic panel is an insulating structure. 
     In another particular embodiment, the hygienic panel includes a front panel and a back panel, and wherein each of the front and back panels include an overlapped outer edge, and wherein the overlapped outer edges of both front and back panels are abutted and connected together by a weldment that effectively seals the hygienic panel. The overlapped edges along with the weldment, form a connecting structure that enables hardware such as hinges or other connecting structure to be connected to the hygienic panel without penetrating the interior area of the panel. 
     Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a dryer incorporating the hygienic door or panel of the present invention. 
         FIG. 2  is a front elevational view of the hygienic door. 
         FIG. 3  is a fragmentary perspective view of the hygienic door with portions broken away to better illustrate the internal structure thereof. 
         FIG. 4  is a view taken through the line IV-IV of  FIG. 2 . 
         FIG. 4A  is an enlarged view of the portion circled in  FIG. 4 . 
         FIG. 5  is a top plan view of the hygienic door illustrating a hinged arm and a portion of a latching assembly. 
         FIG. 6A  is a fragmentary perspective view showing the latching assembly for the hygienic door in an unlatched position. 
         FIG. 6B  is a view similar to  FIG. 6A  but showing the latching assembly in a latched position. 
     
    
    
     DETAILED DESCRIPTION 
     With further reference to the drawings, the dryer of the present invention is shown therein and indicated generally by the numeral  10 . Dryer  10  is a commercial or industrial dryer that is utilized to dry a wide variety of products, particularly food products such as cereal, grains, fruits and vegetables as well as animal food. Details of the dryer are not dealt with herein because such is not per se material to the present invention and because dryers of the type shown in  FIG. 1  and discussed herein are well known and appreciated by those skilled in the art. For a more complete and unified understanding of the basic components of such conventional dryers, one is referred to the dryers that are presently being manufactured and sold by Buhler Aeroglide Corporation headquartered in Cary, N.C. 
     In any event referring to the dryer  10 , it should be noted that the same includes a frame structure  12  that supports the dryer and is utilized to support various components of the dryer. As seen in  FIG. 1 , dryer  10  includes an exterior surface that is typically partially made up of a combination of doors and panels. Defined within the anterior of the dryer  10  is an interior area for receiving products to be dried. There is provided inside the dryer a support structure for receiving and holding the product being dried. In the embodiment illustrated herein, the support structure includes an endless conveyor  14  that moves the product in a conventional fashion through the dryer. In addition, as shown in  FIG. 1 , dryer  10  includes a heating unit indicated generally by the numeral  16 . Typically the heating unit includes one or more burners, such as gas burners, and one or more fans for directing air over the burners in order to heat the air. Thereafter the heated air is circulated in an appropriate fashion through the anterior area of the dryer  10  in order to dry the product therein. 
     As seen in  FIG. 1 , the dryer  10  includes one or more hygienic or sanitary doors or panels. The doors or panels function to enable access to the interior of the dryer  10  for inspecting products or for cleaning or performing maintenance. In the embodiment illustrated herein, the dryer includes mostly doors that can be opened for inspection and maintenance. It is understood and appreciated that the construction for the doors and panels are essentially the same except for the doors being provided with hardware that enables them to be swung open and closed. The panels on the other hand are provided with means to attach and detach them from the frame structure  12 . In the following description, there will be a focus on the door but again it is understood that the panel would include the same basic structure in terms of the outer panels, interior construction, and how the outer panels are attached together. 
     With reference to  FIGS. 2-5 , one door of the dryer is shown therein and indicated generally by the numeral  20 . This door is referred to as a hygienic or sanitary door. The term hygienic door or sanitary door means that the door is closed and sealed and that substantially no air is permitted to enter the interior of the door. This prevents bacteria from growing in interior areas of the door. 
     In the embodiment illustrated herein, door  20  includes a front panel indicated generally by the numeral  22  and a rear panel indicated generally by the numeral  24 . Front and rear panels  22  and  24  are secured together in such a fashion that the inside area of the door, defined by the two panels  22  and  24 , is generally airtight. Various materials, such as stainless steel, can be used for the front and back panels  22  and  24 . 
       FIGS. 3 and 4  show detailed views of how the front and back panels  22  and  24  are constructed and secured together as well as details of the interior design of the door  20 . Note that the front panel  22  includes a front face  22 A that is substantially planar. This is particularly illustrated in  FIG. 4 . Further front panel  22  includes a reinforced outer edge  22 B. See  FIG. 4A . In the case of this embodiment, the reinforced outer edge  22 B is formed by folding a narrow outer strip of the front panel over a relatively narrow interior portion of the front panel. This effectively forms a two-ply construction around the edge of the front panel  22 . Note that the two-ply construction or the reinforced outer edge  22 B is turned at an angle of approximately 90 degrees with respect to the planar front face  22 A. Thus as seen in  FIGS. 4 and 4A , the reinforced outer edge  22 B is at least twice as thick as the front face  22 A. 
     Back panel  24  is of a similar construction. Back panel  24  includes a planar back portion  24 A. In addition back panel  24 A includes a pair of side portions  24 C that extend inwardly towards the front panel  22  at an angle of approximately 90° with respect to the planar back portion  24 A. Like the front panel  22 , the back panel  24  includes a reinforced outer edge  24 B. Reinforced outer edge  24 B is constructed in similar fashion as the reinforced outer edge  22 B of the front panel  22 . Here again a relatively thin outer portion of the back panel  24  is folded over a relatively narrow portion of the back panel to form a two ply construction. Again the two ply construction that forms the reinforced outer edge  24 B is at least two times as thick as the planar back portion  24 A. 
     It should be appreciated that the reinforced outer edges  22 B and  24 B extend completely around the respective front and back panels  22  and  24 . 
     Front and back panels  22  and  24  are secured together in such a fashion as to form a generally airtight seal. More particularly, the reinforced edges  22 B and  24 B are abutted together as shown in  FIG. 4  and a weld seam  26  is utilized to secure the reinforced edges  22 B and  24 B together. More particularly, in this embodiment, the weld seam  26  is laid along an outer edge of the two reinforced edges  22 B and  24 B such that the weld seam engages both reinforced edges and effectively seals them. See  FIG. 4A . 
     Front and back panels  22  and  24  form an open interior area indicated by the numeral  28 . That is, there is defined a space that is bounded by the front and back panels  22  and  24 . 
     Secured in the open space  28  is a honeycomb panel  30 . Honeycomb panel  30  includes a multiplicity of open ended cells that extend generally perpendicular to the front and back panels  22  and  24 . See  FIGS. 3 and 4 . Honeycomb panel  30  can be constructed of various suitable materials such as aluminum, titanium, graphite and ceramic materials. The honeycomb panel  30  is secured in the front or outside portion of the interior of the door  20 . More particularly the honeycomb panel  30  is secured by glue to the back of the front face  22 A. This is typically accomplished by utilizing a vacuum press. Secured to the other side of the honeycomb panel  30  is an intermediate panel  32  that is secured intermediately within the open space  28 . One side of the honeycomb panel  30  is glued to the interior or intermediate panel  32 . Again, the manner of securing the interior panel  32  to the honeycomb panel  30  can vary but in one embodiment an adhesive is utilized to secure the two components together. Various materials can be used for the interior panel  32 . In one embodiment a phenolic sheet of material is utilized as the interior panel  32 . 
     Honeycomb panel  30  adds rigidity and structural strength to the hygienic door  20 . In addition because of the substantial air spaces that are found in the multiplicity of cells, the honeycomb  30  also serves as a thermal break. 
     Dispose on the interior side of the interior panel  32  is an insulation structure  34 . Various types of insulation structures can be utilized but in this embodiment the insulation structure comprises a ceramic fiber blanket that is suspended by a stainless steel wire  36 . More particularly, as viewed in  FIG. 3 , a series of clips  38  are secured to the interior panel  32  and the stainless steel wire  36  is attached to the respective clips and strung therebetween in a zigzag fashion while also being attached to the ceramic fiber blanket  34 . Therefore, as viewed in  FIGS. 3 and 4 , the interior of the hygienic or sanitary door  20  includes the honeycomb panel  30  disposed about the outer portion of the door and the insulation structure  34  disposed about an inner portion of the door. The intermediate or interior panel  32  extends between the honeycomb panel  30  and the insulation structure  34 . 
     Door  20  includes hardware for attaching it to the frame structure  12  of the dryer  10 . In providing for the attachment of hardware to the door  20 , the design implemented is a design where no fasteners project through the front and back panels  22  and  24  into the interior area of the door. This approach assists in providing a hygienic or sanitary door because by not providing such openings to the interior of the door it is possible to provide a design where the interior of the door is generally airtight. Therefore as will be discussed below, the hardware is secured to the mounting structure described above which is essentially the reinforced edges  22 B and  24 B which are in turn secured together by the weld seam  26 . 
     Hardware utilized by the hygienic door  20  is shown in  FIGS. 2 ,  4 ,  5 ,  6 A and  6 B. The hardware includes a pair of hinge arms  50  that are mounted to the top and bottom portions of the door  20  along one side. See  FIG. 2 . In this case, each hinge arm  50  is welded to the reinforced edges  22 A and  22 B. In particular, each hinge arm  50  is welded to the outermost reinforced edge which in the case of this design is the reinforced edge  22 B of the front panel  22 . While the hinge arms  50  might be welded directly to only one reinforced edge, it is the combined structure of the two reinforced edges  22 B and  24 B that provide structural support for the hinge arms  50  and the other attaching hardware. Note that each hinge arm  50  includes an opening  50 A. See  FIG. 5 . Furthermore each hinge arm  50  is adapted or configured to attach to a hinge arm support  52  which is secured to a portion of the frame structure  12  and projects therefrom. See  FIG. 4 . A hinge pin interconnects each hinge arm support  52  and each hinge arm  50 . This enables the hygienic door  20  to swing from an open position to a closed position. 
     Mounted to the other side of the hygienic door  20  is a latching assembly indicated generally by the numeral  60 . See  FIGS. 6A and 6B . Latching assembly  60  includes a lower mounting plate  62  that also serves as a locking plate. Lower mounting plate  62  as viewed in  FIGS. 6A and 6B  is attached to the reinforced edges  22 A and  22 B by weldment. A series of opening  62 A is provided in the lower mounting plate  62 . There is also provided an upper mounting plate  64  that is secured to the hygienic door above the lower mounting plate  62 . An actuating shaft  66  is rotatively journaled in the lower and upper mounting plates  62  and  64 . Actuating shaft  62  is connected to a lower locking plate  68  that includes a series of opening  68 B and a locking finger  68 A. Secured to the upper portion of the actuating shaft  66  is an upper locking plate  70  that includes a locking finger  70 A. 
     As seen in  FIGS. 6A and 6B  there is a locking pin carrier  72  fixed to the lower portion of the actuating shaft  66  and rotatable therewith. Further there is provided a handle  74  that is typically connected to a tab  76  that is fixed to the actuating shaft  66  and projects therefrom. A locking pin  78  is attached to the handle  74  and projects therefrom downwardly through openings in the locking pin carrier  72 . Connected to the frame structure  12  adjacent where the upper and lower locking plate  68  and  70  reside is a pair of locking finger receivers  80 . When the lower and upper locking plate  68  and  70  are disposed in the locked position as partially shown in  FIG. 6B , the locking fingers  68 A and  70 B project into the locking finger receivers  80  so as to lock the hygienic door  20  in a closed and sealed position. Note in  FIG. 4  the presence of the gasket  82  which forms a seal between the hygienic door  20  and the frame structure  12 . 
       FIG. 6A  shows the latching assembly in the unlatched position. To latch and/or lock the hygienic door  20 , the door is closed and the handle is raised such that the locking pin  78  clears the lower locking plate  68 . By rotating the handle  74  the lower locking plate  68  is rotated to where the locking finger  68 A carried thereby engages and locks within the lower locking finger receiver  80  as shown in  FIG. 6B . Now the handle  74  can be pressed down and this will cause the locking pin  78  to be inserted downwardly through a respective opening  62 A in the lower mounting or locking plate  62 . Now the hygienic door is firmly locked in the closed position and the seals  82  form a sealed relationship between the hygienic door  20  and the frame structure  12 . 
     The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.