Patent Publication Number: US-6658869-B1

Title: Microcontroller ice maker

Description:
I. BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention is an improved ice maker, incorporated into the existing water supply and electrical connection within the freezer compartment of a refrigerator, the improved ice maker having a microcontroller that coordinates the making of ice in the ice maker through temperature sensors, electric heater arrays separating the frozen ice cubes from the tray of aluminum cups which form the ice cubes, the temperature sensors keying the process of heating the tray, rotating the tray, ejecting the cubes, and returning the tray to position to form new ice cubes, during which a bail arm is lowered to check the level of ice in the storage container which holds the ejected ice cubes, the bail arm sensing the amount of ice cubes in the container to determine if more ice is needed. The ice maker also has sensors to determine if a problem has occurred in the ice maker, signaling the microcontroller to cancel the ice making process and activate a warning system to alert the consumer that the ice maker is experiencing a problem which needs to be remedied and the ice maker in need of being reset to resume function. 
     2. Description of Prior Art 
     The following United States patents were discovered and are disclosed within this application for utility patent. All relate to ice makers, but none of them utilize the microcontroller which controls the actions and operation of the devices. 
     U.S. Pat. Nos. 5,329,786 and 5,160,094 to Willis disclose ice makers which involves an ice tray having a heater element to partially thaw the ice from the ice maker after which ejector blades force the ice from the tray into an ice bin. This device includes a thermostat which controls the start process of the ice ejection, which comprises the electrical circuit constituting several switches, a motor and a thermostat. This device senses water in the ice tray, commences an ejection process where the ice tray remains stationary and the blades rotate in a circular pattern, with some heat applied to the ice tray to promote removal of the ice from the tray, and a bale arm rotates up and down in a cycle to indicate whether to continue ice production or not, with a sensor to stop the ice making process when the bale arm gets stuck in the ice. The bale arm is generally down when at rest. 
     An ice maker with a heater to assist in dislodging ice from the trays is also disclosed in U.S. Pat. No. 4,833,894 to Chesnut, having a fuse in the heating element to prevent overheating of the ice. In U.S. Pat. No. 4,233,819 to Stottmann, an ice maker is disclosed having a rotating ice tray with concave cups on opposing sides of a rotating axis filled with cryogenic liquified gas to freeze ice in the tray and release the ice when inverted as new water is added to the tray on the opposite side of the axis, this cycle repeating perpetually, with the cryogenic liquid gas cooling the empty tray by fluid gravity. 
     None of these or any other patent searched discloses an ice maker with the microcontroller controlled circuitry of the present invention, nor does it employ a combination of ice tray rotation with retractable ejector arms, a heating device attaching to the tray, water level sensors, thermal sensors and a bale arm which is in the upright position, traveling downward to check the level of the ice in the storage bin, returning to an upright position when inactive, nor do the previous inventions have any reset means to indicate a variety of system failures derived from circuit feedback causing the ice maker to halt further ice production until the problem is remedied. 
     II. SUMMARY OF THE INVENTION 
     The primary objective of the invention is to provide an ice maker controlled by a programmed microcontroller to expedite the efficient production of ice, the microcontroller coordinating the filling of ice to the tray, the determination of when the ice is frozen, the mechanical ejection process including the rotation of the ice tray while heating the ice tray, the spring-loaded ejection process, the return of the ice tray to level, the movement of the bale arm to determine a variable amount of ice in the ice bin under the ice maker, and the continued cycle of the above ice making process, with a system signal return indicating the working order of the system to continue the ice making cycle. 
     A secondary objective of the invention is to have the bale arm positioned up and out of the way at rest to prevent damage to the bale arm during removal of the ice storage bin. 
     A third objective of the invention is to provide the ice maker with a constant safety status monitor to deactivated the system when a system problem of failure is noted in the programming due to a component malfunction of cessation of programmed operation until the problem is remedied. A fourth objective of the invention is to reduce the number of moving components in the ice maker fro prior art ice makers to reduce the number of moving component failures, as well as general failure of moving components due to movement and friction associated with normal operation over time. 
    
    
     III. DESCRIPTION OF THE DRAWINGS 
     The following drawings are submitted with this utility patent application. 
     FIG. 1 is a perspective view of the invention. 
     FIG. 2 is a reverse perspective view of the invention. 
     FIG. 3 is a front view of the invention. 
     FIG. 4 is a top view of a cylindrical cup on the ice tray. 
     FIG. 5 is a cross section of a cylindrical cup with a cross section of an electric heater resistor. 
     FIG. 6 is a front view of the PC board with the attached electrical components. 
     FIG. 7 is a rear view of the PC Board with the attached electrical components. 
     FIG. 8 is a circuit diagram of the ice maker. 
     FIGS. 9 a - 9   d  are a representative flow chart of the operation of the ice maker. 
    
    
     IV. DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention, as shown in FIGS. 1-8 of the drawings, is a microcontroller operated ice maker  10  attaching to a wall of a freezer compartment of a refrigerator, utilizing an existing water line and an electrical supply within the freezer compartment, the ice maker  10  essentially comprising a grounded combination heat sink support bracket  40 , a low voltage electrical motor  42 , a metal ice tray  50  having a plurality of cylindrical cups  54 , a means  12  of ejecting ice cubes from the metal ice tray  50  during rotation of the metal ice tray  50 , a means  13  of heating the metal ice tray  50  to aid in the removal of the ice cubes from the metal ice tray, a multiplicity of electrical components  14 , including a programmable microcontroller  20 , attaching to a PC board  15  to compel the operation of the ice maker  10 , a water level indicator  70 , a water temperature indicator  74 , a means  16  of sensing the level of ice in an ice cube bin  100  to determine whether to continue the production of ice cubes by the ice maker  10 , and a means  18  of monitoring the ice maker  50  to deactivate the ice maker  50  in the event of a failure within the ice maker  50 . 
     More specifically, as shown in the electrical schematic, designated as FIG. 8 of the drawings, the ice maker  10  comprises the grounded combination heat sink support bracket  40  attaching to the wall of the freezer compartment, further attaching to and supporting a reversible low voltage electric motor  42  having a motor shaft  44 , a power supply transformer  21 , a large capacitor  22 , a fast acting fuse  23 , the programmable microcontroller  20 , the metal ice tray  50  having the plurality of cylindrical cups  54 , each having cylindrical sides  56  and a bottom  58 , the metal ice tray  50  attaching to the support bracket  40  by a support rod  60 , the support rod  60  exposed through the bottom  58  of each of the cylindrical cups  54  with an ejection arm  62  attached to the support rod  60  in the bottom  58  of each cylindrical cups  54 , the ejection arms  62  causing ice cubes formed in the cylindrical cups  54  to be ejected when the support rod  60  is rotated, a plurality of electric heater resistors  64  attached to an underside  52  of the metal ice tray  50 , at least one electronic water level indicator  70  and at least one water temperature indicator  74  in at least one of the cylindrical cups  54 , a motor arm  80  attaching to the motor shaft  44 , an ejector arm  82  attached to the support rod  60 , at least one spring  84  attaching the motor arm  80  to the ejector arm  82 , an arm catch  86 , an upright bin level bail  90 , a bin level motor  92  with a bin level adjustment means  94 , an ice cube bin  100 , a bin level hall switch  24 , a rotation hall switch  26  and a position hall switch  28  to monitor the position and rotation of the metal ice tray  50  during the operation of the ice maker  10 , a voltage regulator  27 , an oscillator  28 , at least two optoisolators  29 , at least two triac switches  30 , a plurality of resistors R 1 -R 15 , a plurality of capacitors C 1 -C 5 , a plurality of transistors Q 1 -Q 4 , an LED  34 , a diode D 1 , a reset switch  36 , and the PC board  15  upon which the multiplicity  14  of electronic components are affixed, pursuant to FIGS. 6 and 7 of the drawings. 
     The program by which the microcontroller  20  controls the ice maker  10  is shown in the logic flow chart indicated in FIGS. 9 a - 9   d  of the drawings. As indicated in this flow chart, the ice maker  10  includes several opportunities for the ice maker  10  to check a status of the operating system and shut down the system when a problem is sensed or a desired feedback is not obtained. The reset switch  36  must be reset and the problem alleviated before reactivation of the system is allowed. 
     Due to the microcontroller  20  being the central control mechanism, as again indicated in the flow chart in FIGS. 9 a - 9   d , system shutdown occurs when one of several event occurs. First, if the ejection arm  62  fails to return to a home position, sensed by the rotation hall switch  25  and the position hall switch  26 , due to the failure of the metal ice tray  50  to return to a level position, failure of the ejection arm  62  to return to the its position in the bottom  58  of the cylindrical cups  54 , or the support rod  60  does not turn, the system deactivates and a problem is signaled by the illumination of the LED  34 . If the electric heater resistors  64  take too long to heat the ice tray  50 , the system deactivates and the LED  34  is illuminated. If the electronic water level indicator  70  takes too long to indicate that the cylindrical cups  54  are full of water, the system deactivates and the LED  34  is again illuminated. 
     The basic operation of the ice maker  10  commences by first installing the ice maker to the wall in the freezer compartment of the refrigerator and attaching the water supply and electrical supply to the ice maker. The ice maker  10  is positioned with the cylindrical cups  54  in an upright position to receive water. Water fills the cylindrical cups  54  until the water level indicator  70  senses a filled level, most preferably by an electrical bridge between two stainless steel plates  72 , with the electrical bridge completed by the water between the two stainless steel plates  72 . 
     The water flow is ceased and the ice is formed, until such time as the water temperature indicator  74 , most preferably a 10K @25 degree centigrade NTC Thermistor sensor  76 , is activated, signaling the microcontroller  20  to commence a cycle to empty the ice from the ice tray  50 . The electronic heater resistors  64  are activated, attached to the underside  52  of the ice tray  50 . The reversible low voltage electric motor  42  begins to turn the motor shaft  44  connected to the support rod  60 , commencing a tilting of the metal ice tray  50  and the ejection arms  62 , separating the metal ice tray  50  from contact with the support bracket  40 , until a programmed point is reached, preferably thirty degrees from horizontal, at which time an ice tray catch  59  on the support bracket  40  stops the ice tray  50  rotation. At the same time the motor arm  80  and the ejector arm  82  begin to move with the spring  84  attached between the motor arm  80  and the ejector arm  82  tightening to a point where the motor arm  80  pulls the ejector arm  82 , and the electric motor  42  further rotates the motor arm  80  another ten degrees, at which time the electric motor  42  deactivates. The electronic heater resistors  64  continue to heat until the ice cubes are released from the cylindrical cups  54 , wherein the spring pressure causes the ejection arms  62  to lift the ice cubes from the bottom  58  of the cylindrical cups  54 . The movement of the ejection arms  62  is approximately an eighth of an inch from the bottom  58  of the cylindrical cups  54 , the ejection arm  82  arrested by the arm catch  86  which movement signals the microcontroller  20  to deactivate the electric heater resistors  64 . The electric motor  42  rotates the motor arm  80  another short period releasing the arm catch  86 , rapidly releasing the ejection arms  62  propelling the ice cubes from the cylindrical cups  54  into the ice cube bin  100 . 
     The bin level bail  90  is then lowered to a set level determined by the bin level adjustment means  94 , into the ice cube bin  100 . If the ice cube bin  100  is full, the microcontroller  20  turns off the electrical motor  42 . No ice is produced until some ice is removed from the ice cube bin  100 . If the ice cube bin  100  is not full, the microcontroller  20  reverses the electrical motor  40  raising the bin level bail  90  by activating the bin level motor  92  and returning the ice tray  50  to its horizontal position. The ice tray  50  is thus positioned against the support bracket  40  dissipating the heat of the ice tray  50  during contact, promoting a quicker cooling of the ice tray  50  and expediting the formation of ice in the ice tray  50 . The microcontroller  20  signals the water supply to provide water to the cylindrical cups  54  in the ice tray  50 , and the cycle continues unless a problem in the system is detected, at which time the microcontroller  20  deactivates the ice maker  10  and illuminates the LED  34  until the detected problem is remedied and the reset switch  36  is activated, allowing the ice maker  10  to resume operation. 
     The means  12  of ejecting the ice cubes from the metal ice tray  50  is disclosed in a best mode above by the interaction of the support rod  60 , the ejection arms  62  in the bottom  58  of the cylindrical cups  54 , the motor arm  80  and ejector arm  82 , and the spring  84 . The means  16  of sensing the level of ice in the ice cube bin  100  is performed by the bin level bail  90 , the bin level sensor  92 , the bin level hall switch  24  and the bin level adjustment means  94 . The means  13  of heating the metal ice tray  50  is accomplished by the electric heater resistors  64  attached to the underside  52  of the metal ice tray  50 , and the means  18  of monitoring the ice maker is performed by the interaction of the microprocessor  20  and the multiplicity  14  of electrical components. 
     Most preferably, the plurality of cylindrical cups  54  are constructed on a common base creating the metal ice tray  50  to form multiple ice cubes. The support rod  60 , approximately 0.25 inches in diameter, passes through one end of the base of the metal ice tray  50 . along the bottom  58  of each of the cylindrical cups  54 , out the other end of the metal ice tray  50 , as indicated in FIGS. 2,  3  and  5  of the drawings. The support rod  60  is exposed in the bottom of each of the cylindrical cups  54  as it passes through the base of the metal tray. Attached to the support rod  60  at a ninety degree angel, resting on the bottom  58  and coinciding with the center of each cylindrical cup  54  are one of each of the ejection arms  62  that lift the ice cubes from each cylindrical cup  54  when the support rod  60  is rotated relative to the metal ice tray  50 . 
     The ejector arm  82  is securely fastened on the support rod  60  where it extends from the metal ice tray as shown in FIG. 2 of the drawings. The support rod  60  extends through the support bracket  40 . providing pivotal support for one end of the metal ice tray  50 , while the opposing end of the metal ice tray  50  is directly pivotally attached to the support bracket  40 . 
     The motor  42  is drivingly coupled through the motor arm  80 , springs  84 , and ejector arm  82  to the support rod  60 . The support rod  60  and the metal ice tray  50  rotate in unison until the ice tray catch  59 , formed as part of the support bracket  40 , engages the base of the metal ice tray  50  stopping its rotation thirty degrees from vertical. The support rod  60  rotates another sixty degrees, raising the ejection arms  62  pushing the ice cubes from the cylindrical cups  54 . 
     Most preferably, two stainless steel plates  70 ,  72  are fastened to the cylindrical cups  54  as indicated in FIGS. 3-5 of the drawings, extending downward approximately 0.375 inches into the cylindrical cups  54 , spaced apart approximately 0.0625 inches, electrically insulated from the metal ice tray  50 . A very small amount of voltage is applied to one of the plates  70  and when enough water has bridged the space between the plates  70 ,  72 , the electric current through the water creates approximately 2.5 volts at the second plate  72 . This voltage is programmed as the full point in the microcontroller IC 2  program. To prevent flooding from a malfunction, the program also includes a maximum fill time within the program. 
     The water temperature sensor  74 , is specifically identified as the 10 k @25degrees centigrade NTC Thermister  76 . To keep the Thermister  76  temperature equal to the cylindrical cups  54  temperature, the Thermister  76  is fastened in close physical contact with the outside of one of the cylindrical cups  54 . The 20 k resistor R 1  is connected between the 5 VDC power source off the voltage regulator  27  an one of the leads of the Thermister  76 . while another lead of the Thermister  76  is connected to a system ground. The voltage present at the connection of the Thermister  76  and resistor R 1  is approximately 2.88 volts when the metal ice tray  50  is filled with water. The voltage increases to 3.8 volts when the ice cubes become frozen. 
     When the electrical heater resistor  64  energizes, warming the metal ice tray  50 , the voltage decreases to 3.2 volts and the ice cubes are released and ejected from the cylindrical cups  54  by the previously described ejection method. The voltage present at the Thermister  76  and resistor R 1  junction is connected to pin  17  of the microcontroller IC 2 , and the microcontroller is programmed to generate controls based upon the voltage detected on pin  17 . 
     In a preferred embodiment, as shown in FIGS. 6-8 of the drawings, the multiplicity  14  of electrical components attaching to the PC board  15  which the ice maker  10  utilizes includes a PIC16C71 microcontroller  20 , which has been found to produce the operational programmed result. The two triac switches  30 , used to switch AC power with in the system, are preferably T410-600 B snubberless triac switch. The reset switch  36  is preferably an SPST switch, and the fuse  23  is preferably a TR-5 fast acting 1 amp fuse. The optoisolators  29  are most preferably MOC3042 semiconductors and the electrical heater resistors  64  are best embodied as at least five 25 watt 25 ohm power resistors in series. Additionally, in the preferred embodiment, there area total of 15 resistors R 1 -R 15 , ranging from 330 ohms to 40 K ohms, four capacitors C 1 -C 4 , ranging from 0.1 μF to 1.0 μF, ten semiconductors, including the microcontroller  20 , the two snubberless triac switches  30 , the bin level hall switch  24 , the rotation hall switch  25  and the position hall switch  26 , the voltage regulator  27 , the oscillator  28  and the two optoisolators  29  listed above, four transistors Q 1 -Q 4 , one diode D 1 , and one LED  34 . 
     While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that changes in form and detail may be made therein without departing from the spirit and scope of the invention.