Abstract:
An evaporator plate made of a metal plate having a plurality of shaped dimples thereon, the dimples each being defined by a pair of opposing pyramid shaped end faces and a pair of trapezoidal shaped left and right side faces adjoining the pair of pyramid shaped end faces. An evaporator assembly comprising first and second evaporator plates and tubing arranged in a serpentine path sandwiched therebetween, each plate including a plurality of parallel fins extending from a first surface, a pair of end flanges parallel to the fins, and a plurality of the shaped dimples. A tool for making the plate and a method of making the assembly are disclosed.

Description:
[0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/699,171 filed Sep. 10, 2012, the application being incorporated herein in its entirety by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an evaporator plate assembly for use in an ice making machine. More particular, the present invention relates to an evaporator plate assembly having a pair of dimpled plates between which a serpentine tube is positioned, the plates being spot welded to each other. 
       DESCRIPTION OF RELATED ART 
       [0003]    Automatic ice making machines are well known and are typically found in food and drink service establishments, hotels, motels, sports arenas and various other places where large quantities of ice are needed on a continuous basis. Some automatic ice making machines produce flaked ice while others produce ice shaped in a variety of configurations, which are commonly referred to as cubes or nuggets. 
         [0004]    Automatic ice making machines generally include a refrigeration system having a compressor, a condenser and an evaporator; a series of individual ice forming locations which may or may not be referred to as pockets; and a water supply system. In a typical ice making machine, the evaporator section of the refrigeration system is connected to the series of individual ice forming locations wherein the individual ice forming locations are directly cooled by the refrigeration system. Water may either be supplied to fill the ice forming locations if the ice forming locations are in the form of a series of pockets or water may be supplied to the ice forming locations by having the water trickle over or be sprayed onto the individual ice forming locations. The run-off of the trickled or sprayed water is usually recirculated within the water supply. The trickling or spraying methods of supplying water are normally preferred because the methods produce clear ice while the static filled pockets method generally produce white or opaque ice. 
         [0005]    Automatic ice making machines are normally controlled by the level of supply of the ice in the storage portion of the ice making machine. When the supply of ice in the storage portion is insufficient, automatic controls cycle the ice making machine through ice production and ice harvest modes to supplement the supply of ice in the storage portion. In the production mode, the refrigeration system operates in a normal manner such that expanding refrigerant in the evaporator removes heat from the series of ice forming locations, freezing the water to form an ever growing layer of ice. When the ice thickness reaches a predetermined condition or a specified time period has elapsed, the ice making machine switches to harvest mode. 
         [0006]    Typically the harvest mode involves a valve change which directs hot refrigerant gasses to the evaporator. The ice forming locations are heated by the hot refrigerant gasses until the ice in contact with the evaporator begins to thaw. Once the ice eventually falls from the evaporator, the refrigeration system is changed back to production mode, and the cycle begins again. The ice making machine continues to cycle between the production mode and the harvest mode until some type of sensing system in the storage portion signals the refrigeration system to pause. 
         [0007]    Conventionally, evaporators are formed by bonding evaporator tubes and partitions to a base wall. The evaporator tubes and the base wall are normally made of copper, which is then plated with tin to protect the copper from oxidation. Forming the copper tubes may create residual stresses in the copper, which may cause cracks with rapid expansion and contraction continuously seen in evaporators. 
         [0008]    If copper tubes are left untreated, the tubes corrode over time due to moisture containing dissolved oxygen. The resulting film from this oxidation can flake off into the circulation tank. The tin coating shields the tubes from this harmful process. However, high heat added during the forming process or exposure to high chlorine environments can accidently remove the protective layer in localized areas. 
         [0009]    Moreover, the use of copper material for the tubes presents additional issues. For example, the copper must be pre-cleaned by dipping the copper in a chemical or acid cleaning bath and then coated with tin; which results in high lab and manufacturing costs, as well as potentially making workers ill from the fumes emanating from the various chemicals and the like. A tin tape is then laid over the corresponding portions of the respective front and back evaporator plates. The tin plated copper tube is then placed between the tin tape on each evaporator plate and the evaporator plates and tin plated copper tube are joined or sandwiched together, and the assembly is then brazed together. 
         [0010]    The manufacturing process is rather time consuming, exhausts high amounts of raw materials, such as water, chemicals, copper and tin, and is relatively expensive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0011]      FIG. 1  is an isometric view of an evaporator plate assembly according to a preferred embodiment of the invention and that is preferably incorporated into an ice making machine; 
           [0012]      FIG. 2  is an enlarged front view of an evaporator plate showing a plurality of dimples arranged between a plurality of ribs; 
           [0013]      FIG. 3  is a schematic diagram illustrating end and side faces of a representative dimple; 
           [0014]      FIG. 4  is a perspective view of a dimple forming tool; 
           [0015]      FIG. 5  is a plan view of an upper surface of the dimple making tool shown in  FIG. 4 , wherein a plurality of dimple dies are shown on the upper surface of the tool; 
           [0016]      FIG. 6  is a side view of the dimple making tool shown in  FIG. 4 ; 
           [0017]      FIG. 7  is an enlarged view of a dimple die shown in  FIG. 6 ; 
           [0018]      FIG. 8  is a side view of the dimple making tool shown in  FIG. 4 ; 
           [0019]      FIG. 9  is a cross-sectional view of dimples formed in opposing evaporator plates welded to crushed tubing provided between the evaporator plates; 
           [0020]      FIG. 10  is a cross-sectional view of  FIG. 9  showing a schematic diagram of an ice nugget fowled in a pair of dimples located above and below a crushed portion of the tubing; and 
           [0021]      FIG. 11  is a graph comparing the ice manufacturing capabilities of conventional evaporator plate assemblies relative to the first and second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0022]    The assembly  1  includes a first evaporator plate  10  joined to a second evaporator plate  20  with serpentine tubing  30  disposed between the first and second evaporator plates  10 ,  20 . Preferably, the first and second evaporator plates  10  and  20  are made of stainless steel, however, it is within the scope of the present invention for the tubing  30  to be manufactured from copper that is dipped in tin. 
         [0023]    Of course, it is also within the scope of the invention for the plate  10 ,  20  and tubing  30  to be manufactured from any other suitable material, now known or future developed, that provides, at a minimum, the desired benefits and performance of stainless steel and/or copper dipped in tin. 
         [0024]    Each plate  10 ,  20  includes a plurality of ice forming locations  40 , which may also be interchangeably referred to herein as dimples, wells, and the like. As shown in  FIG. 1 , the first plate  10  includes a plurality of dimples  40  separated from neighboring dimples  40 , on left and right sides, by vertically extending fins  11 . Preferably, the width between neighboring fins  11 ,  11  is approximately 35 mm as measured from a peak of one fin  11  to a peak of a neighboring fin  11 . An inside width between neighboring fins  11 ,  11 , measured from opposing faces of the neighboring fins  11 ,  11  is approximately 29 mm to 30 mm. A left end of the first plate  10  includes a rib  12   a  and a right end of the first plate  10  includes another rib  12   b , which opposes the rib  12   a . It should be noted that while the ribs  12   a  and  12   b  are preferably of the same or uniform height relative to each other, the ribs  12   a  and  12   b  have a greater vertical height compared to each of the fins  11 ,  11 . 
         [0025]    Similarly, the second plate  20  includes a plurality of dimples  40  that are separated from neighboring dimples  40  by fins  21 ,  21 , which are configured in the same manner as the fins  11 ,  11  of the first plate  10 . Also, the left and right ends of the second plate  20  have ribs  21   a  and  21   b , which oppose each other. Moreover, the rib  12   a  of the first plate  10  faces away from the rib  21   b  of the second plate  20 , while the rib  12   b  of the first plate faces away from the rib  21   a  of the second plate  20 . See  FIG. 1  for above-described configuration. 
         [0026]    The plates  10 ,  20  may be manufactured by any known or future developed process. Preferably, a blank sheet of stainless steel having suitable proportions, including length, width and thickness, is fed into an appropriate apparatus or machine wherein the sheet is at least one of folded, pressed, die-stamped, milled, and the like to form the ribs  12   a ,  12   b  and  21   a ,  21   b , and fins  11 ,  21 . Either concurrently or subsequent to the formations of the ribs  12   a ,  12   b  and  21   a ,  21   b  and fins  11 ,  21 , the dimples  40  are formed in each of the plates  10 ,  20  between neighboring pairs of fins  11 ,  21 . 
         [0027]    Turning to  FIG. 2 , which is a front view of an enlarged portion of the assembly  1  shown in  FIG. 1 , a plurality of dimples  40  are illustrated. Although the side and end faces described below are actually curved when viewed from the side, when viewed from above, each dimple  40  is defined by a pair of opposing pyramid shaped end faces  40   a  and  40   b , a pair of trapezoidal shaped left and right side faces  40   c  and  40   d , and a substantially planar valley  40   e . Opposing ends of the valley  40   e  connect the end faces  40   a  and  40   b , while opposing left and right side faces of the valley  40   e  connect the side faces  40   c  and  40   d .  FIG. 3  is a schematic diagram illustrating the end faces  40   a ,  40   b , side faces  40   c ,  40   d , and valley  40   e . It should be noted that it is also within the scope of the present invention for the dimples  40  to be free of the planar valley  40   e  such that the opposing side faces  40   c  and  40   d  directly abut against each other (not shown). 
         [0028]      FIG. 4  is a perspective view of a dimple forming tool  50  that is used to form the dimples  40  in the plates  10 ,  20 . The dimple forming tool  50  includes first and second dimple dies  51  and  52 , respectively, projecting from an upper surface of the tool  50 . 
         [0029]    Referring to  FIG. 5 , which is a plan view of the tool  50  shown in  FIG. 4 , the first and second dimple dies  51  and  52  include opposing inner sloped surfaces  51   d  and  52   d . As shown in  FIGS. 6 and 7 , the inner sloped surfaces  51   d  and  52   d  have a radius Rd that is in a range of between 30° and 60°, but preferably between 40° and 50°, and even more preferably have a radius of 43°. The inner sloped surfaces  51   d  and  52   d  form the side face  40   d  of each dimple  40 . 
         [0030]    Outer sloped surfaces  51   c  and  52   c  of the first and second dimple dies  51  and  52  face away from each other and form the side face  40   c  of each dimple  40 . Opposing sloped ends  51   a  and  51   b  and  52   a  and  52   b  of the dimple dies  51  and  52 , respectively, form the end faces  40   a  and  40   b  of each dimple  40 . The apex of each dimple die  51  and  52 , includes a substantially planar surface  51   e  and  52   e  which form the valleys  40   e ,  40   e  of each dimple  40 ,  40 . For the embodiment of the dimple  40  that is free of the planar valley  40   e , the dimple dies  51  and  52  are similarly formed to be free of the corresponding planar surfaces  51   e  and  52  which form the valleys  40   e ,  40   e.    
         [0031]    Moreover, opposing side faces of the planar surfaces  51   e  and  52   e  of each die  51  and  52 , respectively, join the inner sloped surface  51   d  and  52   d  to the outer sloped surfaces  51   c  and  52   c , respectively. Moreover, opposing ends of the planar surfaces  51   e  and  52   e  of each die  51  and  52 , respectively, join the sloped ends  51   a  and  52   a  to their corresponding other sloped end  51   b  and  52   b , respectively. In the embodiment of the die  50  that is free of the planar surfaces  51   e  and  52   e , the outer sloped surfaces  51   c  and  52   c  directly abut against corresponding inner sloped surfaces  51   d  and  52   d.    
         [0032]    As shown in  FIG. 8 , which is a side view of the dimple die  50 , the sloped ends  51   a  and  52   a  and  52   a  and  52   b  have an angle Ae that is in a range of between 30° and 60°, but preferably between 40° and 50°, and even more preferably have an angle of 47°. 
         [0033]    To manufacture the evaporation plate assembly  1 , the plates  10  and  20  are first manipulated to form the fins  11  and  21  and ribs  12   a ,  12   b  and  21   a ,  21   b , respectively, in the manner discussed above. The tubing  30  is then positioned between the plates  10  and  20 , and the plates  10  and  20  are then welded to each other and/or to the tubing  30 . It is within the scope of the present invention for the plates  10 ,  20  and tubing  30  to be welded using any known or future developed welding method, but it is preferable that the plates  10 ,  20  and tubing  30  are joined by one of spot welding, ultrasonic welding, cold welding, and the like. It is also within the scope of the present invention for the plates  10 ,  20  and tubing  30  to be joined using mechanical joining techniques, such as a slot and groove system, and clamping the plates  10 ,  20  together in a manner that fixedly secures the tubing  30  between the plates  10 ,  20 . 
         [0034]    Subsequent to the joining of the plates  10 ,  20  and tubing  30 , the dimple forming tool  50  ( FIG. 4 ) is used to form the dimples  40  in the plates  10 ,  20  while simultaneously crushing the tubing  30  there between. It is also within the scope of the present invention for the dimples  40  to be formed concurrently or at the same time as when the plates  10 ,  20  and tubing  30  are joined together. 
         [0035]    Referring to  FIG. 9 , it can be seen that the dimples  40  are formed by the first and second dimple dies  51  and  52  of the dimple forming tool  50 , wherein the dimples  40 ,  40  of the plates  10  and  20 , completely surround the tubing  30 , which increases the heat transfer area, translates to high ice production and is more efficient than conventional evaporator plate assemblies. Turning to  FIG. 2 , it can be seen that each pair of dimples  40 ,  40  is formed around or above and below the tubing  30  (when view from the front of each plate  10 ,  20 ) passing between the dimples  40 ,  40  along the back surface of each plate  10 ,  20 . Returning back to  FIG. 9 , the tubing  30 , which has a circular cross-sectional shape (not shown) before the tool  50  forms the dimples  40 ,  40  in the plates  10  and  20 , is flattened or crushed into an oval shape once the dimples  40 ,  40  are formed. 
         [0036]    Furthermore, the radius Rd of the inner sloped surfaces  51   d  and  52   d  of the dimple dies  51  and  52 , respectively, result in an outer surface of the side face  40   d  of each dimple  40  having the same radius Rd, such that the outer surface of each side face  40   d  provides a fairly snug or tight fit with a corresponding outer surface of the crushed or flattened tubing  30 . As can be seen in  FIG. 9 , a substantial, and preferably entire, portion of the outer surface of the crushed tubing  30  is in direct contact with an aspect of the plates  10  and  20 . The above-described structural configuration of the dimples  40 ,  40  relative to the crushed tubing  30  provides an increased service area, which results in the water passing over the plates  10 ,  20  and dimples  40 ,  40  freezes faster, which ultimately produces a faster harvest of ice cubes Ic with a substantial increase in the amount of ice cubes Ic being harvested per refrigeration cycle. 
         [0037]    In operation, once the evaporator plate assembly  1  is installed in a refrigeration system, whether conventional or future developed, during the ice making operation or production mode, water is directed from the top of each plate  10  and  20 , down the channels defined by the neighboring vertically extending fins  11 ,  11  and  21 ,  21 , and over the dimples  40 . Expanding refrigerant passing through the tubing  30  freezes the water passing over the dimples  40 . 
         [0038]    As shown in  FIG. 10 , which is a cross-sectional view that is orthogonal relative to the cross-sectional view of  FIG. 9 , wherever there is tubing  30  passing behind the plate  10 , an ice cube or nugget Ic is formed. The ice cube Ic initially begins with a flat back surface  71 , which is essentially parallel to an upper surface of the plate  10  but eventually becomes rounded around the tube  30  such that the ice cube Ic can be described as having a crescent shaped front surface  72 . Furthermore, the back surface  71  of the ice also includes a pair of projections or legs  73 ,  74  that are &amp;limed by the water in the dimples  40 ,  40  freezing. 
         [0039]    The above-described ice-making process is carried out such that the exposed surface of the plates  10  and  20  is entirely or at least substantially covered with ice cubes Ic. Preferably, there is a water tank beneath the evaporator plate assembly  1  to catch run-off water falling from the plates  10 ,  20 . The run-off water is then recycled through the refrigeration system and over the plates  10 ,  20  until it is determined that there is an insufficient amount of water left in the circulation tank due to the amount of ice cubes Ic formed on the plates  10 ,  20 . 
         [0040]    The refrigeration system then switches from production mode to harvesting mode, during which a hot gas is directed through the tubing  30  and/or water passes between the plates over the tubing  30 . The projections  73 ,  74  of each ice cube Ic then fall or slide out of a corresponding dimple  40  and the cube Ic is collected in a bin (not shown) below the plates  10 ,  20 . An innovative aspect of the crescent shaped front surface  72  and projections  73 ,  73  extending from the substantially flat back surface  71  prevent neighboring ice cubes Ic from sticking to each other in the collection bin (not shown). 
         [0041]    Current conventional evaporator plate assemblies use copper tubes that are coated with tin according to NSF requirements. The brazing, acid washing and coating of the copper tubes result in high labor and material costs, not to mention causing illness to laborers from inhaling or making skin contact with the various chemicals involved in such processes. The all stainless steel aspect of the above-described innovative evaporator plate assembly  1 , according to a preferred embodiment of the invention, eliminates tin-tape, brazing and tin-plating while able to maintain or increase production of the ice nuggets Ic. Moreover, the all stainless steel evaporator plate assembly  1  eliminates all of the chemicals used for fluxing prior to tin plating of the tubes, eliminates all chemicals needed for acid cleaning of the tubing, eliminates tin silver solder needed for joining the evaporator plates and tube plating, saves energy due to elimination of the infrared oven need to heat the conventional plate and tubing assembly process, greatly reduces water use, and greatly reduces air make up and exhaust air requirements. In essence, the innovative evaporator plate assembly  1  provides a more environmental friendly assembly than is currently available in the marketplace. 
         [0042]    Furthermore, the all stainless steel aspect of the evaporator plates assembly  1  presents possibilities wherein each assembly  1  may easily be removed from the refrigeration system by a technician to be cleaned, serviced and possibly even replaced. 
         [0043]    While the preferred embodiment of the evaporator plate assembly  1  described above includes components which are all made of stainless steel, as an innovative aspect of the invention is the configuration of the dimples relative to the crushed tubing between the evaporator plates, it is also within the scope of the present invention to provide an embodiment having a copper tube that is plated with tin. 
         [0044]    That is, instead of using tin tape and brazing to join the copper tubing to the evaporator plates, a second embodiment of the present invention includes tin plating a copper tube which is then spot welded to the evaporator plates before being crushed by the dimple making tool in the manner described above. A motivation for implementing the second embodiment of the innovative evaporator plate assembly having the tin plated copper tubing is a significant increase in ice production. That is, referring to the graph shown in  FIG. 11 , it can be seen that conventional or standard evaporator plates KM having tin tapes and brazed copper tubes typically produces 478 pounds of ice. The all stainless steel evaporator plate assembly HK according to the preferred embodiment of the invention provides an increase in ice production of 484 pounds over the 478 pounds produced by the conventional evaporator plates KM. 
         [0045]    Moreover, when the tin plated copper tubes are used with dimples that are narrower HK copper (Narrow) than the dimples  40  described above, the production of ice increases 15%-16% to 555 pounds of ice. Even more significant is that when the wider dimples  40  described above HK copper (Wide) are used, it can be seen that production of ice increases up to 25% compared with the conventional tin taped copper tubing assembly KM used in the conventional evaporator plate assembly. 
         [0046]    The second embodiment produces more ice cubes Ic than the all stainless steel embodiment and is more resistant to corrosion due to the tin plated copper tubing, which must be counter balanced with the manufacturers concerns and costs associated the additional materials and chemicals needed with the second embodiment relative to the first, all stainless steel embodiment. 
         [0047]    Compared to the conventional KM evaporator plate assemblies, the tin plated copper tubing or second embodiment of the present invention, HK copper (Narrow) and HK copper (Wide) eliminate the cleaning and soldering that is necessary with the conventional KM assembly, while the preferred or all stainless steel embodiment eliminates the additional manufacturing processes and materials, chemicals and the like associated therewith that are noted above. 
         [0048]    While the invention has been described in conjunction with regards to specific aspects, it is evident that various changes and modifications may be made, and the equivalents substituted for elements thereof without departing from the true scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that this invention not be limited to the particular aspects disclosed herein, but will include all embodiments within the spirit and scope of the disclosure.