BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a clear ice maker unit having the features of the present invention;
FIG. 2 is a perspective view thereof similar to FIG. 1 albeit with its cabinet door open so that the interior of the cabinet is visible;
FIG. 3 is a perspective view of a clear ice maker evaporator of the ice maker unit of FIG. 1;
FIG. 4 is a sectional view taken along line 4-4 of FIG. 5;
FIG. 5 is a sectional view taken along line 5-5 of FIG. 4;
FIG. 6 is a sectional view of a partially filled ice bin with an uneven ice distribution;
FIG. 7 is a sectional view of a partially filled ice bin with an even ice distribution;
FIG. 8 is a sectional view of a filled ice bin with an even ice distribution;
FIG. 9 is diagram of the refrigeration system of the ice maker unit of FIG. 1;
FIG. 10 is a schematic of the control system of the ice maker unit of FIG. 1; and
FIG. 11 is a flow chart for determining whether to initiate a next ice making cycle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-2, a clear ice maker 30 includes a cabinet 32 with an upper forward opening 34 and an interior 36. The opening 34 is closed by a door 38 that is hinged to the cabinet 32. The interior 36 includes an ice making area 40 in the upper portion of the cabinet 32 and a bin area 42 below the ice making area 40. The ice making area 40 includes a clear ice maker assembly 44. As discussed below, the clear ice maker assembly 44 is electrically connected to a controller 46 and connected to a refrigeration system 48. The bin area 42 includes a rectangular ice bin 50. The bin area 42 and ice in the ice bin 50 are not cooled by the refrigeration system 48. Both the cabinet 32 and the door 38 are formed of inner molded plastic members and outer formed metal members with the space filled with an insulating layer of foam material, all of which is well known in the art. Thus, ice in the ice bin 50 is insulated from the ambient air.
Referring now to FIGS. 2-5, the clear ice maker assembly 44 is positioned in the ice making area 40. The clear ice maker assembly 44 includes a metal evaporator grid 70 mounted in a plastic shroud 72. The evaporator grid 70 has a series of vertical and horizontal dividers 70a and 70b, respectively, which extend from a rear wall 74 and between lateral edges to divide the evaporator grid 70 into a series of pockets. As best shown in FIG. 3, the horizontal dividers 70b slope towards the bottom front of the evaporator grid 70.
The shroud 72 is formed of a plastic material such as a polypropylene or ABS and is molded about the evaporator grid 70. The shroud 72 has a continuous bulbous edge which engulfs the edges of the evaporator grid 70. The shroud 72 has laterally extending wing portions 76 projecting from each end of the evaporator grid 70. A bib portion 80 of the shroud 72 is disposed beneath the bottom edge of the evaporator grid 70 and contains integral projecting deflector fins 82. Each deflector fin 82 is aligned with the center of a column of pockets in the evaporator grid 70.
The shroud 72 also includes an inclined roof 86 disposed above the evaporator grid 70. A water distributor 88 is attached to the shroud wings 76 above the roof 86. As shown in FIG. 5, the distributor 88 has a floor 90 with a central well 92 at one edge. Spaced upright barriers 94a and 94b extend from the floor 90 beyond the well 92. A second series of spaced barriers 96a, 96b, et seq. extend between the barriers 94a and 94b and a rear edge 98 of the floor 90. Water deposited in the well 92 will be directed by the barriers 94 and 96 to flow uniformly over the rear edge 98 and on to the inclined roof 86. The water will thereafter flow over the roof 86 of the shroud 72, and into and over the surfaces of the pockets in evaporator grid 70. Uniform distribution of the water is further ensured by a guide 100 that has a top opening 102 that receives an end of a water tube 103 and a cylindrical wall section 104 that fits around a portion of the well 92. The guide 100 fixes the water tube 103 at the middle of the distributor 88. The water tube is also secured in place by a rivet connection to the top of the cabinet 32.
An ice maker evaporator 108 is attached to the rear wall 74 of the evaporator grid 70. The ice maker evaporator 108 is a part of the refrigeration system 48 shown schematically in FIG. 9.
Referring now to FIG. 9, the refrigeration system 48 includes a compressor 120, an accumulator 122, the ice maker evaporator 108, a hot gas bypass 124, a condenser 126, a condenser fan 128, and a dryer 130. The compressor 120, condenser 126 and condenser fan 128 are located at the bottom of cabinet 32 beneath the insulated portion, as shown in FIG. 2. The evaporator 108 has an outlet line 132 that passes through the accumulator 122 to the compressor 120. The output of the compressor 120 is connected to an inlet of the condenser 126 having an outlet line 134 connected to the dryer 130. A capillary tube 136 leads from the dryer 130 to an inlet of the evaporator 108. As is known, the compressor draws refrigerant from the evaporator 108 and accumulator 122 and discharges the refrigerant under increased pressure and temperature to the condenser 126. The hot refrigerant gas entering the condenser 126 is cooled by air circulated by the condenser fan 128. As the temperature of the refrigerant drops under substantially constant pressure, the refrigerant in the condenser 126 liquefies. The capillary tube 136 maintains the high pressure in the condenser 126 and at the compressor outlet while providing substantially reduced pressure in the evaporator 108. The substantially reduced pressure in the evaporator 108 results in a large temperature drop and subsequent absorption of heat by the evaporator 108.
The hot gas bypass valve 124 is disposed in a line 138 between the outlet of the compressor 120 and the inlet of the evaporator 108. When the hot gas bypass valve is opened, hot refrigerant will enter the evaporator 108, thereby heating the evaporator 108 and evaporator grid 70.
Referring now to FIGS. 3-5, a water sump 140 has a trough portion 142 extending beneath the evaporator grid 70. The trough 142 extends along the one side wall of the cabinet 32, along a rear wall, and to an opposite side wall of the cabinet 32. The bottom of the trough portion slopes downwardly to the level of a well 144 in which an inlet 146 of a water pump 148 is mounted. An outlet of the water pump 148 is connected to the well 144 in the distributor 88. A removable stand pipe 152 extends into the sump 140 and leads to an overflow pipe 154. The stand pipe 154 opens to a drain 156 in the bottom of the bin area 42 in the cabinet 32. The drain can be connected to a drain in the home plumbing. Alternatively, the drain may lead to an overflow collector in the space beneath the insulated portion of the cabinet 32. Fresh water from an external source may be provided periodically to the sump 140 through a water fill valve.
In general operation, water from the sump 140 is pumped by the pump 148 to the distributor 88 which delivers a cascade of water over the surfaces of the evaporator grid 70. When the evaporator 108 is connected to receive liquefied refrigerant from the condenser 126, the water cascading over the surfaces of the evaporator grid 70 will freeze in layers and build up to form cubes of ice in the pockets. The pure water freezes first and impurities in the water will be left in suspension in the flowing water. Once the ice cubes are formed, the hot gas bypass valve 124 is opened and heated refrigerant is delivered to the evaporator 108, thereby warming the surface of the evaporator grid 70 until the ice cubes dislodge from the evaporator plate grid 70. The dislodged ice cubes will fall into the bin 50 and are directed away from the trough portion 142 of the sump 140 by the fins 82. Not all water cascading over the surface of the evaporator plate will freeze. The excess water is collected in the trough 142 and returned to the well 144 where it is re-circulated to the distributor 88 by the pump 148. During ice harvest (after each freezing cycle), a charge of fresh water is delivered to the sump 140 by the water fill valve to dilute the water and flush impurities through the overflow pipe 152 and out the drain.
Referring now to FIG. 10, the clear ice maker 30 includes an electrical system 170 for controlling the operation of the compressor 120, a solenoid 172 for the hot gas bypass valve 124, a solenoid 174 for the water fill valve, condenser fan 128, and the water pump 148. The controller 46 is a microprocessor that operates by programmed logic and in response to sensor and user inputs. The electrical system 170 includes a bin thermistor 176 and a liquid line thermistor 178 disposed in the outlet line of the condenser 126. The bin thermistor 176 is mounted to the ice bin 50 at a bin thermistor height 180 as discussed hereinafter. The thermistors are commercially available conventional parts. A user interface control unit 182 mounted near the top of the clear ice maker 30 receives user commands. The control unit 182 includes a display panel 184, a power input 186, a warmer input 188, a cooler input 190 and a light input 192.
Upon initial start-up or restarting with the temperature of the bin thermistor 172 above 35 degrees Fahrenheit, the controller 46 energizes the hot gas bypass solenoid 172 and the water inlet valve solenoid 174 for a period of time. This will fill the sump 140 with fresh water to the level of the overflow pipe 152. Thereafter, the compressor 120, the condenser fan 128 and the water circulation pump 148 are energized. After a short period of time, such as ten seconds, the water fill inlet valve solenoid 174 and the hot gas bypass solenoid 172 are de-energized. The ice maker 30 is now in a freeze cycle of an ice making cycle.
After a certain predetermined period of time into the freeze cycle, such as four minutes, a reading of the liquid refrigerant temperature sensed by the thermistor 178 is taken. This temperature reading will determine the remaining length of time for the freeze cycle and may also be used to set or adjust the duration of the ice harvest cycle. The higher the temperature of the liquid refrigerant, the longer the freeze cycle. For example, if the liquid refrigerant temperature is 80 degrees Fahrenheit, the total freeze time will be about 14 minutes. If the sensed temperature is 100 degrees Fahrenheit, the total freeze time will be about 22 minutes. At a temperature of 120 degrees Fahrenheit, the freeze time will be about 30 minutes.
The controller 46 is programmed so that once an ice making cycle has been initiated, the ice making cycle will continue to completion through ice harvest regardless of the temperature reading of the bin thermistor 176. This prevents the ice making cycle from terminating prematurely thereby ensuring that full-sized ice cubes are formed. When the freeze time has elapsed, controller 46 causes the clear ice maker 30 to enter ice harvest mode in which the compressor 120 remains energized while the water pump 148 and condenser fan 128 are de-energized and the solenoids for the hot gas bypass valve 124 and the water inlet valve 160 are energized. The hot refrigerant gas flowing through the ice maker evaporator 120 will loosen the ice formed in the pockets of the evaporator grid 70 so that the ice can fall into the ice bin 50. A typical harvest cycle lasts approximately 2-3 minute. The length of the ice harvest cycle can be dependent upon the reading of the liquid line thermistor 178. The length of the harvest cycle would thus be adjusted inversely based upon the first sensed temperature of the liquid line thermistor. For example, if the sensed temperature of the liquid line thermistor 178 is 80 degrees Fahrenheit, a harvest cycle of 2 minutes would be used. If the temperature is 100 degrees Fahrenheit or above, the harvest cycle will be reduced in time to 1.5 minutes. The harvest cycle can also be made constant for a range of temperatures or entirely independent of the temperature of liquid line thermistor 178.
At the conclusion of the harvest cycle, the controller 46 determines whether to initiate another ice making cycle based on the temperature of the ice bin thermistor 176, which indicates the level of the ice in the ice bin 50. The ice bin 50 is not cooled by the refrigeration system 50; therefore, the temperature of the ice bin thermistor 176 is determined by the ice in the ice bin 50. As the ice fills the ice bin 50, the ice approaches the bin thermistor 176, which causes the bin thermistor 176 to be cooled. When ice is adjacent to the ice bin thermistor 176 and the bin 50 is uniformly filled with ice, the temperature of the ice bin thermistor 176 will be at its lowest. Thus, the temperature of the ice bin thermistor 176 can be used to control the height of the ice in the ice bin 50 by stopping the production of ice when the temperature of the ice bin thermistor 176 indicates that ice is adjacent to the bin thermistor 176. The ice bin thermistor height 180 can be set to equal the maximum desired ice level in the bin 50 in order to ensure that the bin 50 is not overfilled and to maximize ice production.
Referring to FIG. 8, when the ice fills the ice bin 50 uniformly, the ice level is at or minimally above the bin thermistor height 180 and ice is adjacent the ice bin thermistor 176, the temperature TB of the bin thermistor 176 will be equal to or less than a temperature T1. The temperature TB of the bin thermistor 176 may also be equal to or less than temperature T1 when the ice fills the ice bin 50 non-uniformly but the ice is stacked against the wall of the bin 50 to which the bin thermistor 176 is attached. The controller 46 can be programmed to prohibit the initiation of further ice making cycles when the temperature TB of the bin thermistor 176 is less than or equal to temperature T1. The temperature T1 can vary depending on the configuration of the ice maker 30 and/or environmental conditions. In an embodiment, T1 can be set to 33 degrees Fahrenheit.
Referring now to FIG. 6, it is possible that ice will not also stack up uniformly across the ice bin 50. This can be caused if the slabs of ice are not broken apart into ice cubes when the slabs fall into the bin 50. When the ice does not stack up uniformly across the ice bin 50, it is possible that the ice will reach the maximum desired ice level on one or more sides of the ice bin, but the ice will not be positioned adjacent the ice bin thermistor 176. Thus, the temperature TB of the ice bin thermistor 176 will not reach a temperature below temperature T1, which means that ice production would not be halted and more ice would be produced. Additionally, the ice may stack up non-uniformly across the ice bin 50 so that ice may be adjacent the bin thermistor 176, but the volume of ice adjacent the bin thermistor 176 may not be large enough to cool the bin thermistor 176 sufficiently to reach a temperature below T1. As shown in FIG. 6, the bin 50 has more room for ice, but would overfill after more than a few further ice making cycles without the temperature TB of the ice bin thermistor 176 reaching temperature T1. The temperature TB of the ice bin thermistor 176 may not reach a temperature below temperature T1, but the temperature of the ice bin thermistor 176 will reach a temperature near temperature T1 as the bin 50 fills up with ice. To prevent overfilling the bin 50 when the ice is not stacked correctly in the bin 50, the controller 46 can use fuzzy logic to prohibit the initiation of further ice making cycles when the temperature TB of the bin thermistor 176 is less than or equal to temperature T2 for a period of time X. A temperature TB of thermistor 178 below temperature T2 indicates that the bin 50 is nearly full of ice and/or the ice is not stacked uniformly, which means that the bin 50 has room for more ice, but not too much more ice. The length of the period of time X can be set to allow for the appropriate number of further ice making cycles. The temperature T2 and the period of time X can vary depending on the configuration of the ice maker 30 and/or environmental conditions. In one embodiment, for example, the temperature T2 can be set to 35 degrees Fahrenheit and the period of time X can be set to one hour to allow for three more ice making cycles, which maximizes ice production and minimizes the risk of overfilling the bin 50.
During operation of the ice maker 30, the controller 46 monitors the temperature TB of the ice bin thermistor 176, and logs into memory the temperature TB of the ice bin thermistor 176, and the time the temperature reading was taken so that the controller 46 can analyze the historical temperature data to calculate the time that the temperature TB of the ice bin thermistor 176 is below temperature T2. Alternatively, the controller 46 can be configured to track the period of time that the temperature TB of the ice bin thermistor 176 is below temperature T2.
FIG. 11 shows a decision making process 200 of determining whether to initiate an ice making cycle 202. Beginning with an ice making cycle completion 204, the controller 46 determines at decision block 206 whether the temperature TB of the bin thermistor 176 is less than or equal to temperature T1. If the temperature TB of the bin thermistor 176 is less than or equal to temperature T1, the controller 46 does not initiate the ice making cycle 202 and the controller 46 stays in decision block 206. If the temperature TB of the bin thermistor 176 is greater than temperature T1, the controller 46 determines at a decision block 208 whether the temperature TB of the bin thermistor 176 is less than or equal to temperature T2 for more than the period of time X. If the temperature TB of the bin thermistor 176 is less than or equal to temperature T2 for more than the period of time X, the controller does not initiate next ice making cycle 202 and returns to decision block 206. If the temperature TB of the bin thermistor 176 is greater than temperature T2 for more than the period of time X, the controller 46 initiates the next ice making cycle 202. At the end of the ice making cycle 202, the controller 46 returns to ice making cycle completion 204 and restarts the decision making process 200. In an embodiment, the temperature T1 can be 33 degrees Fahrenheit, the temperature T2 can be 34 degrees Fahrenheit, and the period of time X can be one hour.
In order to adapt the ice maker 30 to different environments, running conditions and user preferences, the temperature T1 can be set by a user. For example, the ice maker 30 can be run until the ice bin 50 has a user desired level of ice. The user can then access the current temperature TB of the bin thermistor 176 and set temperature T1 to be equal to the current temperature TB of the bin thermistor 176. The controller 46 is configured so that the user can set temperature T1 through the control unit 182. The user can access current temperature TB of the bin thermistor 176 through the control unit 182. Temperature T2 can be set to equal temperature T1 plus two degrees. Alternatively, the user can also set temperature T2.
It should be appreciated that merely a preferred embodiment of the invention has been described above. However, many modifications and variations to the preferred embodiment will be apparent to those skilled in the art, which will be within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiment. To ascertain the full scope of the invention, the following claims should be referenced.
Patent Application
20080092567
