Abstract:
An ice-making machine that includes an evaporator and a simple control system, with a single switch, that initiates a harvest cycle by determining a flow rate of water out of the evaporator. The evaporator is a coiled in a flat, space-saving spiral.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The following application is a continuation-in-part of U.S. patent application Ser. No. 12/002155, filed on Dec. 13, 2007, and also claims priority to U.S. Provisional Application Nos. 60/898641, filed on Jan. 31, 2007, 60/918842, filed on Mar. 19, 2007, and 61/007864, filed on Dec. 17, 2007. 
     
    
     BACKGROUND OF THE DISCLOSURE 
       [0002]    1. Field of the Disclosure 
         [0003]    The present disclosure relates to ice-making machines. More particularly, the present disclosure relates to ice-making machines having a control system to detect when ice has been formed within the machine, and to initiate the harvest of the ice. 
         [0004]    2. Discussion of the Related Art 
         [0005]    In the field of ice-making machines, it is desirable to have automated machines that produce continuous supplies of ice, while still maintaining mechanical simplicity and efficient use of resources such as power and water during the ice-making process. The machines of the prior art can require the use of costly and/or complicated control mechanisms that tell the machine when the ice-making cycle is complete, and the ice can be harvested. 
         [0006]    Accordingly, there is a need for an ice-making machine that overcomes the aforementioned disadvantages of the machines of the prior art. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    The present disclosure provides an ice-making machine that can comprise a spiral-shaped, flat evaporator tube. In this type of evaporator, ice is formed inside the evaporator tube. The evaporator has one or more water passages and one or more refrigerant passages disposed therein. Water and refrigerant are supplied to the evaporator, and the water is frozen inside the water passages by the conductive effects of the refrigerant while disposed within the evaporator. The ice-making machine of the present disclosure also comprises a water reservoir, a sump and an ice storing bin. Water that passes through the evaporator before it is frozen empties into the reservoir. The machine further comprises a sensor, such as an air pressure sensor, disposed within the reservoir. When the flow rate of water into the reservoir drops below a certain level, the water in the reservoir will drop below a certain level, indicating that the water has frozen within the evaporator. The sensor detects that the water level has dropped below a desired level and closes a switch, which powers a hot gas solenoid valve, which then sends warm refrigerant through the refrigerant passages. This loosens the ice within the evaporator, which is then pushed by water flow through the evaporator into the ice holding bin, where it can be collected by a user. 
         [0008]    When the ice in the evaporator has been completely ejected, the water flow through the evaporator and into the reservoir resumes. This reestablished flow raises the level of water in the reservoir. This higher water level is detected by the air pressure sensor which then opens a switch, de-energizing the hot gas solenoid valve and causing the evaporator to cool off and resume freezing water, 
         [0009]    The present disclosure thus provides an ice-making machine that comprises an evaporator, wherein the evaporator is wound in a spiral, so that it does not grow substantially in height with each revolution of the evaporator, and a control system comprising a single switch that senses water level in a reservoir located at an outlet of the evaporator. 
         [0010]    The present disclosure also provides a method of harvesting ice from an ice-making machine, wherein the ice-making machine comprises an evaporator and a reservoir. The method comprises the steps of: detecting the level of water in the reservoir, wherein water exiting the evaporator is directed into the reservoir, directing a flow of hot gas through the evaporator when the level of water in the first reservoir drops below a first point, ejecting ice from the evaporator, and shutting off the flow of hot gas to the evaporator when the level of water in the reservoir is above a second point. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]      FIG. 1  is a front view of an ice-making machine of the present disclosure; 
           [0012]      FIG. 2  is a top, perspective view of the ice-making machine of  FIG. 1 ; 
           [0013]      FIG. 3  is a partial top view of the ice-making machine of  FIG. 1 ; and 
           [0014]      FIG. 4  is a schematic diagram of the control system of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    Referring to  FIGS. 1-3 , an ice-making machine (“machine”)  10  of the present disclosure is shown. Machine  10  further comprises evaporator  20 , which can be covered with an insulating material  21 , one or more refrigerant inlet pipes  25 , one or more refrigerant outlet pipes  26 , water tube  30 , reservoir  40  and bin  50 . In the embodiment shown in  FIGS. 1-3 , there are two refrigerant inlet tubes  25  and two refrigerant outlet tubes  26 . 
         [0016]    The present disclosure provides a control system that can detect when ice forms within evaporator  20 , and thus needs to be harvested. As will be discussed in greater detail below, the control system comprises a few very simple and inexpensive components, and thus provides a highly advantageous way of managing the ice-making cycle of the ice-making machine. 
         [0017]    During operation of machine  10 , water is supplied to evaporator  20  through water tube  30 , which is connected to a first end of evaporator  20 . For example, water can be supplied through water tube  30  with a pump, as will be discussed in greater detail below. Refrigerant is also supplied to evaporator  20  by refrigerant inlet pipes  25 . Refrigerant flows through one or more refrigerant passages, which are disposed within evaporator  20 , and water flows through one or more water passages  70 , also disposed within evaporator  20 . Water flowing through water passage  70  is thus frozen by the refrigerant passing through refrigerant passages  60 . The water within water passage  70  freezes at the outer edges of water passage  70  first, and grows toward the middle of water passage  70 , until the water is frozen solid. This stops the flow of water through the water passage  70 . 
         [0018]    While the water within water passage  70  is freezing, the water that passes through water passage  70  exits at an end  22  of evaporator  20 , and is collected in reservoir  40 . The present disclosure has advantageously developed a control system that can detect when the water within evaporator  20  has frozen, and can send hot gas to evaporator  20 , allowing for the ejection of the ice. 
         [0019]    Referring to  FIG. 4 , reservoir  40  has one or more holes disposed therein, that allow the collected water to drain, providing a “leak rate” of the water collected in reservoir  40 . While the water is freezing in water passage  70  as described above, water flows constantly into reservoir  40  at a rate that exceeds the “leak rate” of reservoir  40 . This causes the level of water to always be at the top of reservoir  40 . As the ice grows inside the evaporator  20 , the water flow rate coming out of end  22  decreases and eventually stops. When the water flow rate has slowed greatly (or stopped), the “leak rate” of reservoir  40  exceeds the incoming water flow rate, and the water level in reservoir  40  drops. 
         [0020]    Water level sensor  45  can be disposed within reservoir  40 , to sense the level of the water within reservoir  40 . Water level sensor  45  can have a tube  47 , which is disposed within reservoir  40 . The rising or falling water level in reservoir  40  creates a change in air pressure within tube  47 . This change in pressure is communicated through tube  47  to switch  48 . Switch  48  senses the air pressure change and opens or closes appropriately to actuate a hot gas valve (not shown). When the water level reaches a desired minimum point, for example, switch  48  actuates to open the hot gas valve, allowing hot gas to flow through refrigerant inlet pipes  25  and into refrigerant passages  60 . The hot gas enters the refrigerant passages  60 , and loosens the ice formed within water passage  70 . The ice will then automatically eject due to the pressure of the water being pumped into evaporator  20  through water tube  30 . The ice can be diverted away from falling into reservoir  40  by a grate  43  that directs the ice into bin  50 , where it can be collected by a user. 
         [0021]    In some cases, it may be advantageous to start the flow of the hot gas before the flow of water into reservoir  40  completely stops, and the point at which switch  48  actuates can be set accordingly. Water level sensor  45  can also be a float switch, which would also send a signal to switch  48  when the water level within first bin  40  drops below a desired level. 
         [0022]    Once the ice has been ejected from evaporator  20 , water will again begin to flow through end  22  of evaporator  20 , and into reservoir  40 . The water level within reservoir  40  will rise to the point where it resets water level sensing switch  45 , which then turns off the supply of warm refrigerant to refrigerant passages  60 . Cold refrigerant then flows again through refrigerant inlet pipe  25  and into refrigerant passages  60 . Water level sensing switch  45  is thus a significantly less expensive and simpler way of controlling the making of the ice within machine  10  than is available in the machines of the prior art, which often involve complicated and costly electro-mechanical or electronic controls. 
         [0023]    The size and number of the holes within reservoir  40  should be adjusted so that, before water is frozen within water passages  70 , the flow rate of water entering reservoir  40  exceeds the leak rate of water exiting reservoir  40 . This will ensure that water level sensor  45  closes the hot gas valve as described above. In addition, the holes should be sized so that only a full flow of water out of evaporator  20  will keep reservoir  40  full. At times, the water will start to flow again out of evaporator  20  even when the ice within has not been fully harvested. The holes within reservoir  40  should provide a sufficient leak rate out of reservoir  40  to prevent the reactivation of the freezing cycle when this partial harvest condition occurs. 
         [0024]    As also seen in  FIG. 4 , the present disclosure provides a sump  90 , pump  32 , and float valve  92 . Water draining from reservoir  40  is directed into sump  90 . Pump  32  runs continuously, circulating water through evaporator  20 . If the water level in sump  90  drops below the desired level, for example after the ice is harvested from evaporator  20 , float valve  92  opens to refill sump  90  to the predetermined level. The water used to refill sump  90  can come from an external water source. 
         [0025]    Sump  90  also has overflow drain  94  disposed therein. During the ice making cycle when the water flow slows, water empties out of reservoir  40  and into sump  90 . This water raises the level of water in the sump  90  and causes water to overflow down drain  94 . This regular overflow of water each cycle is needed to prevent excessive concentration of impurities in the ice making water. Excess impurities in the ice making water can lead to cloudy ice and formation and precipitation of lime scale into sump  90 . 
         [0026]    As is shown in  FIGS. 1-3 , evaporator  20  is a flat, spiral tube. Evaporator  20  is preferably made of an inexpensive, thermally conductive material that is suitable for contact with water. For example, this material can be thermally conductive plastic, or a metal alloy such as brass. In one embodiment, evaporator  20  is made of an aluminum alloy. Evaporator  20  can also be coated with a corrosion-resistant material, and/or anodized. In addition, evaporator  20  can comprise a variety of orientations of water passages  70  and refrigerant passages  60 . For example, evaporator  20  can have one water passage  70 , and two refrigerant passages  60 , or two water passages  70  and one refrigerant passage  60 . 
         [0027]    While the instant disclosure has been described with reference to one or more exemplary or preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope as described herein.