Patent Publication Number: US-2007101752-A1

Title: Ice-making device utilizing pulse electric devices to harvest ice

Description:
RELATED APPLICATIONS  
      This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/723,853, filed Oct. 6, 2005, the entire contents of which are hereby incorporated by reference, U.S. Provisional Patent Application Ser. No. 60/724,251, filed Oct. 6, 2005, the entire contents of which are hereby incorporated by reference, U.S. Provisional Patent Application Ser. No. 60/724,152, filed Oct. 6, 2005, the entire contents of which are hereby incorporated by reference, and U.S. Provisional Patent Application Ser. No. 60/724,222, filed Oct. 6, 2005, the entire contents of which are hereby incorporated by reference. 
    
    
     1. FIELD OF THE INVENTION  
      The present invention relates to an ice-making machine and, more particularly, to an ice-making machine that harvests ice with electrical pulse energy.  
     2. BACKGROUND OF THE INVENTION  
      One type of conventional ice-making machine is commonly referred to as a “flaker” device. These machines typically comprise a heat exchanger coil wrapped around a cylinder. The coil carries refrigerant, which freezes water inside the center of the cylinder. A scraping device inside the cylinder is used to scrape the ice off the sides of the cylinder. The resulting ice, which consists of small, snow-like pieces of ice is referred to as “flake ice”. These machines, however, can be very complex mechanically.  
      One such flaker device is described in U.S. Pat. No. 4,984,360, which is incorporated herein in its entirety by reference thereto. According to this patent, a typical flaker or auger-type ice-making machine has an elongated hollow, cylindrical or tubular evaporator with an elongated rotatable auger disposed therein. Disposed adjacent the upper end of the evaporator is an annular mounting flange adapted to support an ice extruder and breaker member, as is well known in the art. The auger includes an elongated, generally cylindrical-shaped central body section that is formed with an integral helical ramp or flight portion defining a helical ice shearing edge disposed closely adjacent the inner peripheral wall of the evaporator tube.  
      A refrigeration coil or fluid conduit, which can be composed of a copper-bearing tubing for example, generally surrounds at least a substantial portion of the outer peripheral wall of the evaporator tube and is preferably arranged in a generally helical configuration. As is well known in the art, a supply of ice make-up water is introduced into the interior of the evaporator tube through suitable water supply apparatus in order to form a thin layer of ice continuously around the interior peripheral wall of the evaporator tube. Such ice is formed through the transfer of heat from the ice make-up water through the evaporator tube and the fluid conduit into a heat transfer fluid carried within the fluid conduit, in a manner generally well known in the art. Upon rotation of auger by a suitable drive motor the thin layer of ice is scraped from the interior of the evaporator tube and transferred axially upwardly along the helical flight in order to be compacted or otherwise formed into the discreet ice particles in an upper portion of the ice-making machine.  
      These flaker machines tend to be very expensive to build, however, due to the significant mechanical complexity associated with operating the auger. Hence, there is a strong demand for a flake ice-making machine that avoids the aforementioned expense and provides an ice-making machine that harvests the ice formed on the evaporator in a fast and efficient fashion, thereby reducing the cost and improving the reliability of the icemaker.  
     SUMMARY OF THE INVENTION  
      The ice-making machine of the present disclosure comprises a water supply, a refrigerant supply, an electrical energy source, and a variety of ice-forming surfaces. Water is either sprayed or dripped onto the ice-forming surface, where it is cooled and frozen by refrigerant passing below the surface. Once the ice is formed, an electrical pulse is sent through or below the ice-forming surface, releasing the ice from the surface where it can be collected.  
      In a first embodiment of the invention, the ice-making machine comprises an ice-forming surface that is made of a thermally and electrically conductive material. The refrigerant passes through passages imbedded within the ice-forming surface, freezing the water on the surface. After the water is frozen, an electrical pulse can be supplied through an electrical energy source that is also imbedded in the surface material. The electrical pulse momentarily warms the freezing surface to above the melting temperature of the ice, freeing the ice from the surface. The shape of the ice-forming surface can be either flat or cylindrical.  
      In another embodiment of the invention, the ice-making machine can comprise a plurality of layers with refrigerant tubing disposed on one side, and a water source on the opposite side. Water is sprayed on the surface furthest from the refrigerant tubing, and frozen by the conductive effects of the refrigerant. An electric pulse can then be applied to the cause heating of the surface where the ice is formed, freeing the ice from the surface.  
      In another embodiment of the invention, the ice-making machine can be a cylindrical drum that rotates in a bath of water. The drum is made of a thermally and electrically conductive material. Refrigerant lines pass through the center of the drum, and freeze the water on the outer surface of the drum. The ice is then removed in strips by sending an electric pulse through resistive heaters that are disposed along the outer surface of the drum.  
      Thus, the ice-making machine of the present disclosure harvests ice in a manner that is much simpler mechanically than the flaker devices of the prior art. The ice is harvested with a simple pulse of electrical energy to create heating of the ice making surface. There is no need for a complex mechanical structure to remove the ice from the evaporator. The evaporators of the present disclosure can also be simple flat or cylindrical structures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional perspective view of a first embodiment of the invention;  
       FIG. 2  is a perspective view of a second embodiment of the present invention;  
       FIG. 3  is a cross-sectional view of a third embodiment of the present invention; and  
       FIG. 4  is a perspective view of a fourth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      In the present invention, electrical pulse energy is applied to conductive surfaces that have a layer of ice disposed thereon, and causes immediate resistance heating of the surface. This rapid heating of the surface causes the ice layer to be rapidly melted free from the surface without need for a hot gas defrost, the addition of water, or with a mechanical scraper such as an auger, as required in the ice-making machines of the prior art. This method of freeing this ice greatly simplifies the ice making mechanism, making it more reliable and less expensive.  
      The pulsed energy used for thermal de-icing may be of the type described in U.S. Pat. Nos. 6,870,139 and 7,034,257, and U.S. patent application Publication No. 2004/0149734, all of which are incorporated herein in their entirety by reference thereto, that is capable of supplying pulsed energy. Modulating the pulsed energy to the interface of the ice to the ice-forming surface modifies a coefficient of friction between the ice and the surface. The electrical pulse energy technology is known as Pulse Electro Thermal De-icing (PETD).  
      Typically, a pulse de-icer system heats an interface to a surface of an object so as to disrupt adhesion of ice with the surface. To reduce the energy requirement, one embodiment of a pulse de-icer explores a very low speed of heat propagation in non-metallic solid materials, including ice, and applies heating power to the interface for time sufficiently short for the heat to escape far from the interface zone; accordingly, most of the heat is used to heat and melt only a very thin layer of ice (hereinafter “interfacial ice”). The system preferably includes a power supply configured to generate a magnitude of power. In one embodiment, the magnitude of the power has a substantially inverse-proportional relationship to a magnitude of energy used to melt ice at the interface. The pulse de-icer system may also include a controller configured to limit a duration in which the power supply generates the magnitude of the power. The duration of the pulse can also have a substantially inverse-proportional relationship to a square of the magnitude of the power. The power supply may further include a switching power supply capable of pulsing voltage. The pulsed voltage may be supplied by a storage device, such as a battery or a capacitor. The battery or capacitor can, thus, be used to supply power to a heating element that is in thermal communication with the interface.  
      Referring to  FIG. 1 , a first embodiment of the present invention is shown, and referred to by reference numeral  10 . Ice-making machine  10  has evaporator  20 , a plurality of refrigerant passages  30 , an energy source  40 , a water source  50 , and a power supply  60 .  
      Evaporator  20  is made of a thermally and electrically conductive material. Such materials are well known in the art, and can include aluminum, copper, or thermally conductive plastic. The preferred material for the ice-forming surface is thermally conductive plastic, due to its low cost and ease of manufacture.  
      The plurality of refrigerant passages  30  are formed within evaporator  20 . The thickness of ice evaporator  20  should thus be large enough to accommodate the refrigerant passages  30 . For example, the thickness of evaporator  20  can be between about ⅜″ and ¾″. Water source  50  can be an impinging jet, or any device capable of spreading water onto a surface. Energy source  40  can be the PETD type of energy circuit described above. The refrigerant used in ice machine  10 , or in any of the embodiments discussed below, can be one or more of many known refrigerants in the art.  
      Thus, during operation of the machine  10 , water is sprayed onto the surface of evaporator  20  by water source  50 , where it forms a thin sheet. Water can also be applied onto the surface of evaporator  20  with a drip. The thickness of the sheet formed on evaporator  20  can range from about 0.020″ to about 0.100″. The preferred thickness is about 0.050″. Refrigerant passes through passages  30 , freezing the water on the surface of evaporator  20 . After the ice is frozen and reaches the desired thickness, a pulse is sent through energy source  40 , which frees the ice from the surface of evaporator  20 . The ice can be collected in a bin, where it breaks into smaller fragments. The flow of the water and the refrigerant can be continuous, with a pulse supplied at intervals to evaporator  20 . Ice can be formed on either surface of evaporator  20 .  
      Referring to  FIG. 2 , a second embodiment of the present invention is shown, and referred to by reference numeral  110 . Ice-making machine  110  is virtually identical to ice-making machine  10 , with the exception that evaporator  120  is cylindrical in shape. Evaporator  120  has a plurality of refrigerant passages  130  disposed therein, much in the same way that passages  30  are disposed within evaporator  20  of ice-making machine  10 . In machine  110 , ice can be formed on the inside and/or outside of evaporator  120 . Refrigerant passages  130  can be disposed all the way around evaporator  120 , or only partially around evaporator  120 . When refrigerant passages  130  only cover part of evaporator  120 , there can be passage inlets and outlets disposed near the area of evaporator  120  not covered by passages  130 .  
      The flow of the water and the refrigerant in ice machines  10  and  110  can be continuous, with a pulse supplied at intervals to surfaces  20  and  120 . This makes the ice-making process simpler and easier to control.  
      Referring to  FIG. 3 , a third embodiment of the present invention is shown, and referred to by reference numeral  210 . Ice-making machine  210  has evaporator  220 , a plurality of refrigerant passages  230 , a water source  250 , and an energy source  260 . Evaporator  220  further comprises a first layer  222 , a second layer  224 , a dielectric layer  226 , and a third layer  228 . First layer  222 , second layer  224 , and third layer  228  all comprise thermally and electrically conductive materials. First layer  222  is made of a material that is suitable for contact with potable water. Preferably, first layer  222  is stainless steel, or more preferably thermally conductive plastic. Second layer  224  and third layer  228  are preferably copper. Dielectric layer  226  can be made of any suitable dielectric material known in the art. First layer  222 , second layer  224 , dielectric layer  226 , and third layer  228  can be joined together through known methods in the art, such as with soldering or brazing.  
      Alternatively, ice machine  210  can have three layers, wherein the outer layers are made of thermally and electrically conductive materials, and the middle layer is a dielectric layer. At least one of the outer layers is made of a material suitable for contact with potable water.  
      During operation of ice machine  210 , water source  250  sprays water on to first layer  222 . Refrigerant flows through passages  230 , which are disposed on the opposing side of evaporator  220 , and adjacent to third layer  228 . Water is thus frozen on first layer  222 . A pulse of energy is then sent through first layer  222 , which frees the ice from first surface  222 . As with the above described embodiments, the water and refrigerant can be continuously supplied, and the electrical pulse can be supplied at intervals. The ice can be collected in a bin.  
      Referring to  FIG. 4 , a third embodiment of the present invention is shown and referred to by reference numeral  310 . Ice machine  310  has rotational drum evaporator  320  and refrigerant lines  330 , which pass through the middle of drum evaporator  320 . Evaporator  320  is made of a thermally and electrically conductive material, such as those described above. During operation of machine  310 , evaporator  320  is rotated through a water bath  380 , forming a film of water on the surface of evaporator  320  which is then frozen by the refrigerant flowing through lines  330 .  
      Evaporator  320  has a plurality of resistive heater strips  340  disposed thereon. Pulse generator  350  has a pair of electrical leads  355  that contact the plurality of heater strips  340  as evaporator  320  rotates. Thus, evaporator  320 , electrical leads  355 , and water bath  380  are oriented so that water freezes on the surface of evaporator  320  after being rotated out of the water bath  380 . The ice is then harvested in strips in ice removal zone  360 , when heater strips  340  come into contact with electrical leads  355  of pulse generator  350 . The ice strips can also be chipped off with a scraper. The harvested ice can be collected in a bin.  
      The present invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims.