Patent Application
20210131714
The present subject matter relates generally to nugget-style ice makers.
Certain refrigerator appliances include an ice maker. To produce ice, liquid water is directed to the ice maker and frozen. A variety of ice types can be produced depending upon the particular ice maker used. For example, certain ice makers include a mold body for receiving liquid water. An auger within the mold body can rotate and scrape ice off an inner surface of the mold body to form ice nuggets. Such ice makers are generally referred to as nugget-style ice makers. Certain consumers prefer nugget-style ice makers and their associated ice nuggets.
Controlling operation of nugget-style ice makers can be challenging. Generally, only temperature measurements are used to control operation of nugget-style ice makers. However, in certain circumstances, all liquid water within the mold body can freeze and block rotation of the auger, i.e., the ice maker can “freeze up.” Avoiding and detecting freeze ups with only temperature measurements can be difficult.
Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.
In an example embodiment, a control method for a nugget ice maker includes setting the nugget ice maker to an ice formation operating state and operating a motor of the nugget ice maker to rotate an auger within a casing of the nugget ice maker in the ice formation operating state. The control method also includes monitoring a speed of the motor in the ice formation operating state. The control method further includes switching the nugget ice maker from the ice formation operating state to an ice production operating state in response to the monitored speed of the motor in the ice formation operating state dropping below an ice formation speed threshold. The control method includes operating the motor to rotate the auger within the casing in the ice production operating state. An average speed of the motor in the ice production operating state is less than the average speed of the motor in the ice formation operating state.
In another example embodiment, a control method for a nugget ice maker includes setting the nugget ice maker to an ice formation operating state and operating a motor of the nugget ice maker to rotate an auger within a casing of the nugget ice maker in the ice formation operating state. The control method also includes monitoring a speed of the motor in the ice formation operating state. The control method further includes switching the nugget ice maker from the ice formation operating state to an ice production operating state in response to the monitored speed of the motor in the ice formation operating state dropping below an ice formation speed threshold. The control method includes operating the motor to rotate the auger within the casing in the ice production operating state; and monitoring a temperature within the casing in the ice production operating state. The ice formation speed threshold is about two and one-fifth rotations per minute.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Refrigerator doors 128 are rotatably hinged to an edge of housing 120 for selectively accessing fresh food chamber 122. In addition, a freezer door 130 is arranged below refrigerator doors 128 for selectively accessing freezer chamber 124. Freezer door 130 is coupled to a freezer drawer (not shown) slidably mounted within freezer chamber 124. Refrigerator doors 128 and freezer door 130 are shown in the closed configuration in
Refrigerator appliance 100 also includes a dispensing assembly 140 for dispensing liquid water and/or ice. Dispensing assembly 140 includes a dispenser 142 positioned on or mounted to an exterior portion of refrigerator appliance 100, e.g., on one of doors 120. Dispenser 142 includes a discharging outlet 144 for accessing ice and liquid water. An actuating mechanism 146, shown as a paddle, is mounted below discharging outlet 144 for operating dispenser 142. In alternative exemplary embodiments, any suitable actuating mechanism may be used to operate dispenser 142. For example, dispenser 142 can include a sensor (such as an ultrasonic sensor) or a button rather than the paddle. A user interface panel 148 is provided for controlling the mode of operation. For example, user interface panel 148 includes a plurality of user inputs (not labeled), such as a water dispensing button and an ice-dispensing button, for selecting a desired mode of operation such as crushed or non-crushed ice.
Discharging outlet 144 and actuating mechanism 146 are an external part of dispenser 142 and are mounted in a dispenser recess 150. Dispenser recess 150 is positioned at a predetermined elevation convenient for a user to access ice or water and enabling the user to access ice without the need to bend-over and without the need to open doors 120. In the exemplary embodiment, dispenser recess 150 is positioned at a level that approximates the chest level of a user.
An access door 166 is hinged to refrigerator door 128. Access door 166 permits selective access to freezer sub-compartment 162. Any manner of suitable latch 168 is configured with freezer sub-compartment 162 to maintain access door 166 in a closed position. As an example, latch 168 may be actuated by a consumer in order to open access door 166 for providing access into freezer sub-compartment 162. Access door 166 can also assist with insulating freezer sub-compartment 162, e.g., by thermally isolating or insulating freezer sub-compartment 162 from fresh food chamber 122.
Ice maker 160 also includes a fan 176. Fan 176 is configured for directing a flow of chilled air towards casing 170. As an example, fan 176 can direct chilled air from an evaporator of a sealed system through a duct to casing 170. Thus, casing 170 can be cooled with chilled air from fan 176 such that ice maker 160 is air cooled in order to form ice therein. Ice maker 160 also includes a heater 180, such as an electric resistance heating element, mounted to casing 170. Heater 180 is configured for selectively heating casing 170, e.g., when ice prevents or hinders rotation of auger 172 within casing 170.
Operation of ice maker 160 is controlled by a processing device or controller 190, e.g., that may be operatively coupled to control panel 148 for user manipulation to select features and operations of ice maker 160. Controller 190 can operate various components of ice maker 160 to execute selected system cycles and features. For example, controller 190 is in operative communication with motor 174, fan 176 and heater 180. Thus, controller 190 can selectively activate and operate motor 174, fan 176 and heater 180.
Controller 190 may include a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with operation of ice maker 160. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller 190 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. Motor 174, fan 176 and heater 180 may be in communication with controller 190 via one or more signal lines or shared communication busses.
Ice maker 160 also includes a temperature sensor 178. Temperature sensor 178 is configured for measuring a temperature of casing 170, the cylinder within casing 170, and/or liquids, such as liquid water, within casing 170. Temperature sensor 178 can be any suitable device for measuring the temperature of casing 170 and/or liquids therein. For example, temperature sensor 178 may be a thermistor or a thermocouple. Controller 190 can receive a signal, such as a voltage or a current, from temperature sensor 190 that corresponds to the temperature of the temperature of casing 170 and/or liquids therein. In such a manner, the temperature of casing 170 and/or liquids therein can be monitored and/or recorded with controller 190.
A speed of motor 174 may also be measured or determined by controller 190. For example, ice maker 160 may include a speed sensor (not shown) such as an optical speed sensor, a magnetic speed sensor, etc. As another example, motor 174 may be a brushless direct current (DC) motor with RPM feedback for electronic commutation of motor windings. Thus, motor 174 may include an internal controller that outputs the speed of motor 174 without requiring a separate sensor. It will be understood that the example motor speeds described herein may correspond to a reduced output speed from one or more reduction gears coupled to motor 174.
At 210, method 200 includes setting ice maker 160 to an ice formation operating state. In the ice formation operating state, ice maker 160 operates to begin ice formation on the inner surface of the cylinder within casing 170. Thus, at a start of the ice formation operating state, only liquid water may be disposed in the cylinder within casing 170, and ice maker 160 operates to freeze the liquid water on the inner surface of the cylinder within casing 170. As liquid water within the cylinder in casing 170 cools during the ice formation operating state, the temperature within casing 170 decreases. Thus, a temperature within casing 170 decreases over time during the ice formation operating state.
To assist with ice formation in the ice formation operating state, fan 176 may be activated to circulate chilled air through casing 170 around an exterior of the cylinder. The cylinder within casing 170 rejects heat to the chilled air circulated by fan 176 in order to decrease the temperature of the cylinder and facilitate ice formation on the inner surface of the cylinder within casing 170. Motor 174 may also operate to rotate auger 172 in the cylinder within casing 170 during the ice formation operating state. Rotating auger 172 during the ice formation operating state may assist with detection of ice formation the inner surface of the cylinder within casing 170, as discussed in greater detail below.
At 220, a speed of motor 174 is monitored. For example, as the ice forms within casing 170 during the ice formation operating state, auger 172 may impact such ice, and such impact may change a rotational speed of the motor 174. In particular, interference between auger 172 and the ice on the inner surface of the cylinder within casing 170 may decrease the rotational speed of the motor 174. Thus, the rotational speed of the motor 174 may be relatively high at a beginning of the ice formation operating state and may rapidly decrease towards the end of the ice formation operating state. Monitoring the speed of motor 174 at 220 may thus assist with detecting ice formation on the inner surface of the cylinder within casing 170.
As noted above, the monitored speed of motor 174 from 220 may assist with detecting ice formation on the inner surface of the cylinder within casing 170. When ice forms on the inner surface of the cylinder, ice maker 160 is ready for ice production. Thus, at 230, ice maker 160 switches from the ice formation operating state to an ice production operating state in response to the monitored speed of motor 174 from 220 dropping below an ice formation speed threshold, ST. At the end of ice formation operating state, a temperature within casing 170 (e.g., the cylinder in casing 170, liquid water within the cylinder in casing 170, etc.) may be about twenty-four degrees Fahrenheit (24° F.). As used herein the term “about” means within two degrees of the stated temperature when used in the context of temperatures.
The ice formation speed threshold ST may be selected to assist with detection of ice formation on the inner surface of the cylinder within casing 170. For example, the ice formation speed threshold ST may be about two and one-fifth rotations per minute (2.2 RPM). As used herein the term “about” means within two-tenths of a rotation per minute of the stated speed when used in the context of speeds. Such example ice formation speed threshold ST may advantageously allow accurate and reliable detection of ice formation of on the inner surface of the cylinder within casing 170 during the ice formation operating state and timely shifting to the ice production operating state.
In the ice production operating state, ice maker 160 operates to scape ice flakes from the inner surface of the cylinder within casing 170 with auger 174 and then force such ice flakes through extruder 175 to form ice nuggets. Thus, during the ice production operating state, both liquid and solid water may be disposed in the cylinder within casing 170, and ice maker 160 operates to produce ice nuggets. To assist with ice production in the ice production operating state, fan 176 may be activated to circulate chilled air through casing 170. The cylinder within casing 170 rejects heat to the chilled air circulated by fan 176 in order to cool water within the cylinder maintain a balanced heat transfer between water within the cylinder and air circulated by fan 176.
Motor 174 may also operate to rotate auger 172 in the cylinder within casing 170 during the ice production operating state. An average speed of motor 174 in the ice production operating state is different than the average speed of motor 174 in the ice formation operating state. In particular, the average speed of motor 174 in the ice production operating state may be less than the average speed of motor 174 in the ice formation operating state. For instance, a ratio of the average speed of motor 174 in the ice production operating state to the average speed of motor 174 in the ice formation operating state may be no less than seventy hundredths (0.70) and no greater than seventy-five hundredths (0.75). More particularly, the average speed of motor 174 in the ice production operating state may be about two and three-quarters of rotations per minute (2.75 RPM), and the average speed of motor 174 in the ice formation operating state may be about two rotations per minute (2 RPM).
During the ice production operating state, ice maker 160 may “freeze up” such that all liquid water within the cylinder within casing 170 freezes and locks auger 172. Thus, ice maker 160 cannot make ice nuggets when ice maker 160 freezes up. Method 200 may also include features for detecting when ice maker 160 freezes up and for remediating the freeze up condition.
At 240, a temperature within casing 170 is monitored. For example, temperature sensor 178 may measure the temperature of the cylinder within casing 170 and/or liquids, such as liquid water, within casing 170. The speed of motor 174 may also be again monitored during the ice production operating state at 240. As auger 172 harvests ice flakes during the ice production operating state, the temperature within casing 170 may be generally constant, e.g., at thirty-two degrees Fahrenheit (32° F.). Similarly, the speed of motor 174 may be generally constant as auger 172 harvests ice flakes during the ice production operating state. However, if the ice formation rate on the inner surface of the cylinder within casing 170 exceeds the harvesting rate of auger 172 then the thickness of the ice layer on the inner surface of the cylinder within casing 170 may increase over time and ice maker 160 may eventually freeze up as described above.
The monitored temperature within casing 170 from 240 and/or the monitored speed of motor 174 from 240 may assist with detecting when ice maker 160 freezes up. Thus, at 250, ice maker 160 switches from the ice production operating state to a fix operating state in response to the monitored temperature within casing 170 from 240 dropping below a minimum temperature threshold, MT, and/or the monitored speed of motor 174 from 240 dropping below a minimum speed threshold, MS.
The minimum temperature threshold MT and/or the minimum speed threshold MS may be selected to assist with detection of freeze ups in ice maker 160 or other errors in ice maker 160. For example, the minimum temperature threshold M may be about twenty degrees Fahrenheit (20° F.). As another example, the minimum speed threshold MS may be about one rotation per minute (1 RPM) or about zero rotations per minute (0 RPM). Such example minimum temperature threshold MT and minimum speed threshold MS may advantageously allow accurate and reliable detection of freeze ups in ice maker 160 during the ice production operating state and timely shifting to the fix operating state.
During the fix operating state, motor 174 may be deactivated. Thus, motor 174 may not rotate auger 172 in the fix operating condition. By deactivating motor 174, damage to motor 174 may be reduced or avoided when ice maker 160 is frozen up. During the fix operating state, fan 176 may also be deactivated to terminate or reduce circulation chilled air through casing 170. In addition, heater 180 is activated to heat water within the cylinder in casing 170. Thus, heater 180 may assist with melting ice within casing 170 in the fix operating condition.
Ice maker 160 may operate in the fix operating condition until the freeze up condition is eliminated or suitably reduced. For example, the ice maker 160 may operate in the fix operating condition for a predetermined period of time suitable for deicing the cylinder within casing 170. As another example, the ice maker 160 may operate in the fix operating condition until the monitored temperature within casing 170 exceeds a recovery temperature threshold, e.g., about forty degrees Fahrenheit (40° F.). As may be seen from the above, method 200 may eliminate freeze ups in ice maker 160 in the fix operating condition. After the fix operating condition, method 200 may include returning to the ice formation operating condition, e.g., at 210.
Method 200 advantageously allows distinction between temperature drops due to initial ice formation within the cylinder in casing 170 and freeze ups in the cylinder during ice production. In particular, monitoring temperature as well as motor speed assists method 200 with such distinction. While described above in the context of an air-cooled icemaker, method 200 may also be used with refrigerant-cooled nugget ice maker, e.g., where an evaporator is coupled to the cylinder with auger 172 for directly cooling the cylinder.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
