Smart ice machine with separately fabricated cups for the ice tray

An ice-tray for ice-making machines is formed by modular fabricated cups that can assembled together within a frame to create an ice-tray of arbitrary dimensions allowing a sharing of components among a variety of ice-tray sizes. Individual cups may include ice formation sensors or heaters or may be heated by an induction heating system.

FIELD OF THE INVENTION

The present invention relates to ice-making machines for home refrigerators and the like and specifically to ice-making trays for such machines using a modular design facilitating the production of different sizes of ice-making machines.

BACKGROUND OF THE INVENTION

Household refrigerators commonly include automatic ice-makers, for example, located in the freezer compartment. A typical ice-maker provides an ice cube tray positioned to receive water from an electrically controlled valve that may open for a predetermined time to fill the tray. The water is allowed to cool until ice formation is ensured. At this point, the ice is harvested from the tray into an ice bin positioned beneath the ice-tray. The amount of ice in the ice bin may be checked through the use of the bail arm which periodically lowers into the ice bin to check the ice level. If the bail is blocked in its descent by a high level of ice, this blockage is detected and ice production is stopped.

One method of harvesting ice cubes from the trays employs a tray heater. Typically, in this case, the ice-tray will be a metal die-cast part incorporating an electrical resistance heater which heats the ice-tray to above the melting point of water to release the ice when the tray is inverted by a motor. The electrical resistance heater and the ice-maker motor normally operate directly at a line voltage of about 120 volts AC eliminating the need for external power processing or sophisticated control electronics in the associated refrigerator.

Refrigerators are produced in a variety of sizes in order to provide a cost-effecting and energy efficient option that best fits the needs of different consumers. These different sizes of refrigerators may employ different ice-tray configurations, typically providing anywhere from 6 to 21 ice cubes per tray. The manufacture of different sizes of die cast metal ice-trays can incur substantial tooling costs, for example, in the production of different metal dies, when such a range of different sizes of ice cube trays is desired.

SUMMARY OF THE INVENTION

The present invention provides a modular ice-tray that employs as few as two different ice cube mold modules that can be assembled into ice-trays for molding as few as four cubes to an arbitrarily large number of cubes depending on the number of mold modules employed. The mold modules may be efficiently manufactured in large numbers, for example, by molding or drawing operations and then used for many different tray implementations.

Specifically, the present invention provides an ice-tray for use in an ice-making machine constructed of a set of separately fabricated cups each open at a rim for receiving water into at least one cup volume defining a shape of an ice cube that may be frozen within the fabricated cup and a frame adapted to receive and retain the set of fabricated cups to produce an ice-tray in which the cups open in a common direction from a first side of the frame to receive water from an ice-making machine supporting the frame therein.

It is thus a feature of at least one embodiment of the invention to provide an ice-tray that can be efficiently manufactured in a variety of different sizes with reduced tooling costs.

The set of separately fabricated cups may provide laterally extending channels at the rims of the cups permitting intercommunication of the cup volumes of the separately fabricated cups when assembled together in the frame.

It is thus a feature of at least one embodiment of the invention to provide a self equalizing water flow among the modular fabricated cups necessary for common ice-making machines introducing water at a single location in the tray.

The laterally extending channels may extend in at least two perpendicular directions from each cup volume.

It is thus a feature of at least one embodiment of the invention to provide a modular system that will naturally tile to provide interconnection between the volume of each cup and the volumes of adjacent cups.

The set of cups may include two cup types, a first cup type providing only two laterally extending channels from each cup volume, and a second cup type providing three laterally extending channels extending from each cup volume; whereby two cup types can be assembled into an ice-tray having two rows and an arbitrary number of columns of fabricated cups.

It is thus a feature of at least one embodiment of the invention to provide as few as two types of cups that can be manufactured to produce a wide range of sizes of ice-trays.

The fabricated cups may include a radial flange at the rim abutting a corresponding planar wall on the first side of the frame aligning the cups along the planar wall.

It is thus a feature of at least one embodiment of the invention to provide a simple mechanism of aligning the cups in a common plane for improved water flow equalization between the cups.

The fabricated cups may each provide two cup volumes each defining the shape of one of two different corresponding ice cubes that may be frozen within the fabricated cup

It is thus a feature of at least one embodiment of the invention to minimize the number of components necessary to manufacture common ice-tray types.

The frame may be an injection molded thermoplastic material.

It is thus a feature of at least one embodiment of the invention to provide a relatively low-cost integrating structure that can be used to assemble prefabricated cups together in a variety of different tray sizes. Tooling needed for an injection molded frame can be substantially less than that required for a drawing operation for fabrication of different sizes of trays of metal.

The frame may mechanically capture the separately fabricated cups between thermoplastic elements formed around the fabricated cups.

It is thus a feature of at least one embodiment of the invention to provide a simple method of integrating the dissimilar materials of the cups and frame together into an integrated ice-tray. It is another object of the invention to provide an improved ice-tray that may reduce the thermal mass of the ice cups through reduced thickness drawn metal supported by a robust thermoplastic tray to provide quicker freezing and heat release of the formed cubes.

The ice-tray may further include a sensor communicating with at least one fabricated cup for detecting the state of water within the fabricated cup as being frozen or unfrozen.

It is thus a feature of at least one embodiment of the invention to provide a modular ice-tray that can cycle faster by detecting ice formation.

The sensor may be an electrode pair communicating with a circuit sensing a change in electrical properties between the electrode pair caused by a freezing of water.

It is thus a feature of at least one embodiment of the invention to provide a method of directly sensing ice formation eliminating the need to infer ice formation from temperature and time such as may be inaccurate.

The fabricated cup may provide two electrically isolated halves forming the sensor pair.

It is thus a feature of at least one embodiment of the invention to use the cup itself as the sensing electrodes to provide greater sensing area and thus more robust sensing.

The circuit may analyze at least one of a value of resistance and capacitance between the sensor electrodes to compare that value against a threshold indicating frozen water and unfrozen water.

It is thus a feature of at least one embodiment the invention to provide a flexible method of detecting ice formation.

The circuit may further analyze the value to detect an empty tray.

It is thus a feature of at least one embodiment of the invention to provide a sensor system that can also detect whether an ice-molding volume is empty of ice or water.

The ice tray may further include a heater communicating with the fabricated cups for heating the fabricated cups to release the ice cubes formed in the fabricated cups.

It is thus a feature of at least one embodiment of the invention to provide a method of releasing the ice cubes from the composite tray thus formed eliminating the need to warp the tray as an alternative method of releasing ice cubes.

The heater may be an induction heater communicating with the fabricated cups through a magnetic field inducing eddy currents in the metal of the fabricated cups.

It is thus a feature of at least one embodiment of the invention to provide a simple mechanism of heating multiple cups assembled together in a frame without the need for complex circuitry and interconnection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now toFIG.1, an ice-maker10may include an ice-tray12for receiving water and molding it into frozen ice cubes14of arbitrary shape. The ice-tray12may be positioned adjacent to ice harvest drive16communicating with electrical power and control signals from a refrigerator (not show-in) through power conductors13and with a water supply through water line20.

The ice harvest drive16may fill the ice-tray12, for example, through a fill nozzle22and after the water is frozen, eject cubes14from the ice-tray12, for example, by inversion of the ice-tray12and heating of the ice-tray12until the ice cubes14fall from the ice-tray12. The ice-tray12may be positioned above an ice storage bin24for receiving cubes14therein when the latter are ejected from the ice-tray12.

The ice harvest drive16may provide a drive coupling26exposed at a front wall of a housing of the ice harvest drive16and communicating with the corresponding coupling28on the ice-tray12. The drive coupling26may rotate about an axis30along which the ice-tray12extends thereby rotating the ice-tray12as is necessary for filling the ice-tray12with water and ejecting the ice cubes14from the ice-tray12.

The ice harvest drive16may have a bail arm32that pivots about a horizontal axis generally perpendicular to axis30to periodically swing down into the ice storage bin24to contact an upper surface of the pile of cubes14in the ice storage bin24. In this way the bail arm32may determine the height of those cubes14and deactivate the ice-maker10when a sufficient volume of cubes14is in the ice storage bin24to prevent full descent of the bail arm32.

Referring also toFIG.2, the ice-tray12may be constructed from a set of separate ice-mold cups34each open upwardly from the ice-tray12generally parallel to axis36, perpendicular to axis30and normal to an upper face of the ice-tray12. The upper edge of the ice-mold cups34is defined by a rim38extending laterally outward, generally in a plane perpendicular to axis36. The rim38passes continuously around a periphery of the upper open end of the cups34.

Sidewalls40of the cup34extend downwardly from an inner periphery of the rim38to a bottom wall42parallel to and displaced downward from the rim38. The sidewalls40and bottom wall42together define a cup volume41determining the shape of one or more ice cubes that can be molded in the ice-mold cups34. Although a rectangular prismatic volume41is shown, other shapes such as cylinders, cones, hemispheres, hemi-cylinders and the like are also contemplated by the present invention. Generally each of these volumes41will be arranged to provide for an inward sloping of the sidewalls40as one moves toward the bottom wall42to provide proper draft for removal of the ice cubes14without interference by undercuts or the like.

Hemi-cylindrical channel46a,extending along axis30, or hemi-cylindrical channel46bextending perpendicular to axis30, each lying within a plane of the upper face of the ice-tray12, are formed in the upper edge of some of the sidewalls40so that water filling any one of the volumes41will equalize among the volumes41by means of water passing through the channels46between volumes41as the water approaches a fill level above those channels46. Generally, each volume41of an assembled ice-tray12will communicate either directly or indirectly through the channels46with every other volume41in the ice-tray12when the ice-tray12is in the uptight horizontal position during filling.

Multiple ice-mold cups34may be tiled together in a frame50providing upwardly extending peripheral walls52and internal stiffening divider walls54of equal height, these walls together providing a set of pockets56for receiving the volumes41of the ice-mold cups34therein with a bottom surface of the rim38resting against the corresponding upper surface of the walls52and54.

As so positioned in the frame50, the multiple ice cups34will face upward and will be aligned with the rims38and a common plane. In one embodiment, the frame may be generally rectangular to organize the ice-mold cups34in two rows extending parallel to axis30and an arbitrary but predefined number of columns perpendicular thereto.

The rim38may include cutouts51that pass around corresponding bosses58, for example, extending upwardly from the upper surface of the divider walls54which support the rims when the ice-mold cups34are in place within the frame50. As shown inFIG.3, the boss58may then be staked downward over the rims38of the installed cups34to retain them in the frame50. In one embodiment, the frame50may be constructed of a thermoplastic material and the staking process may be accomplished by ultrasonic or thermal staking or the like which peens down the upper end of the boss58over the surface of the rim38.

Referring alternatively toFIG.4, the boss58may be eliminated and the cups34may be insert molded into the thermoplastic material of the walls52of the frame50. As is understood in the art, insert molding incorporates the mold cups34into a thermoplastic mold to be partially surrounded by molten thermoplastic during the molding process. In both cases, an integrated structure is thereby produced.

Alternatively, the cups34may be press fit into the frame50and for this purpose not have the flange or rim38.

Referring now toFIGS.5and6, with the production of only two different types of cups34aand34b,a variety of different ice-trays12may be produced. In one embodiment, the first type of cup34aprovides an end cup that may fill ends of the frame50opposed along axis30with one of the cups34arotated 180 degrees with respect to the other cup34a.The second type of cup34bmay then be placed between the end cups provided by the first type of cup34ato fill in between these cups34a.InFIG.5, one cup34bmay be used with two end cups34ato create a six-volume ice-tray12. InFIG.6, three cups34bmay be used between two end cups34ato create a 10-volume ice-tray12.

Referring again toFIG.5, end cups34adiffer from cups34bby the locations of the channels46aand46b.Specifically, cup34aprovides only two perpendicular channels46aextending from each cup volume41while cup34bprovides three channels46(two channels46amutually parallel and one perpendicular channel46b) extending from each cup volume41. In this way all cup volumes41of the assembled ice-tray12may intercommunicate with each of its neighbors through a channel46.

Referring now toFIG.7, it will be appreciated that the system of the present invention may also be used with cups34aand34beach having only a single volume41. In this case, the frame50may include mutually perpendicular divider walls54together providing pockets56sized to receive one volume41of one of the cups34. Two cups34ahaving a relative rotation of 90 degrees with respect to each other can fill a first end column of the frame50. A duplicate assembly of two cups34amay then be rotated by 180 degrees to fill the last column of the frame50. Two cups34brotated relatively by 180 degrees may then fill the center columns of the frame50. As before, cup34aprovides only two perpendicular channels46aextending from each cup volume41while cup34bprovides three channels46(two parallel channels46aand one perpendicular channel46b) extending from each cup volume41. In this way all cup volumes41of the assembled ice-tray12may intercommunicate with each of its neighbors through a channel46.

Referring now toFIGS.8and1, when the cups34and frame50are assembled into an ice-tray12, the ice-tray12may connect with the ice harvest drive16through an inter-engagement of couplings28and26described above with respect toFIG.1. Coupling26may be driven by an internal motor drive60controlled by a control circuit62that may rotate the ice-tray12about the axis30as desired for the making of ice under the control of signals generated by the control circuit62and/or from the refrigerator. An example of motor drive60and of other elements and components suitable for use in the ice harvest drive16are described in US patent application 2012/0186288 hereby incorporated in its entirety by reference.

The control circuit62may also communicate with a limit switch64providing an indication of the rotational position of the ice-tray12(e.g., upright or inverted) and the motor drive60operated according to knowledge of this position and a desired state of the ice-maker10. Control circuit62may also control an electrically actuated valve66receiving water line20to controllably provide water to the ice-tray12when the ice-tray12is in the upright position. The control circuit62may further communicate with a limit switch68monitoring the position of the bail arm32to stop the production of ice when no additional ice is needed in the bin24(shown inFIG.1). Further, the control circuit62may receive signals from an ice formation sensor70detecting whether ice is formed in a given volume41of the ice-tray12and send signals to an ice release heater72that may heat the ice cups34to release ice from those cups prior to ejecting the ice by inverting the ice-tray12.

Referring now toFIG.9, the ice sensor70may operate in conjunction with an ice-sensing circuit73, for example, integrated into the control circuit62. The ice-sensing circuit may electrically connect with two sensing electrodes74aand74bcommunicating with the volume41within at least one of the ice cups34so that the sensing electrodes74aand74bare electrically isolated from each other but for electrical flow through liquid or solid water within the volume41. In one embodiment, the electrodes74aand74bmay make use of the walls of the ice cup34themselves as electrically conductive surfaces. In this regard, end ice cup34may be bisected into separate portions75aand75balong a plane parallel to axis36and an insulating divider76inserted therebetween to rejoin the bisected portions75aand75binto a watertight volume41operating in the same manner as an un-bisected cup34but for the electrical isolation between the portions75aand75b.Insulating divider76may, for example, be insert molded to engage with the portions75aand75bor attached by adhesive or other assembly techniques. The ice-sensing circuit73may be attached to sensor electrodes74aand74bsupported by the insulating divider76to communicate with the separate portions75aand75b,respectively, or may be attached directly to, for example, outer surfaces of the portions75aand75b.

In one embodiment, the ice-sensing circuit73provides a DC voltage across the electrodes74aand74bthrough a current limiting resistor80. High conductivity liquid water within the volume41provides a low resistance between the electrodes74aand74breducing the voltage across the electrodes74aand74bsuch as may be sensed by threshold detection amplifier82. Alternatively the ice-sensing circuit73(designated73′ in the inset ofFIG.9) may provide an AC voltage across electrodes74aand74bthrough a current limiting capacitor84. In this case, high dielectric constant liquid water within the volume41provides a high capacitance between the electrodes74aand74breducing the voltage across electrodes74aand74b(in this case AC amplitude) which again may be sensed by a threshold detection amplifier86providing a rectifying action. This latter approach permits the metal of the ice cup34to be anodized or otherwise coated with an electrical insulator which acts simply as an additional capacitance.

Referring now toFIG.10, the signal produced by amplifiers82or86may be compared against several thresholds90, for example, indicating whether the volume41is empty, contains ice, or contains liquid water. The results of this comparison, indicating the state of the volume41, may be in turn compared against a schedule of known operation of the ice harvest drive16to help distinguish between ambiguous states and to allow the application of heat and harvesting of ice more precisely to provide improved energy efficiency.

Referring now toFIGS.11and12, in one embodiment, the heater72shown inFIG.8may be a flexible thick film heater72aformed, for example, using a T-shaped flexible polymer sheet92having a coating of a positive temperature coefficient resistance material94. The positive temperature coefficient, material94provides a resistance that varies according to the temperature of the material94, permitting increased electrical flow at lower temperatures and decreased electrical flow at higher temperatures following a substantially nonlinear pattern as a function of temperature. This property provides for a self-regulating temperature of the heater72awhich may be set close to the melting point of ice for high efficiency heating of the cups32without overheating. Positive temperature coefficient (PTC) materials suitable for the present invention, are also disclosed in U.S. Pat. Nos. 4,857,711 and 4,931,627 to Leslie M. Watts hereby incorporated in their entirety by reference.

Applied over the top of the positive temperature coefficient resistance material94is an electrode array96providing interdigitated electrode fingers promoting current flow through the positive temperature coefficient resistance material94over a broad area of the heater72a.This electrode array96may terminate in eyelets98providing attachment points for other electrical wiring100allowing multiple beater units be connected in parallel or in series. As noted, the heater72amay connect via electrical wiring to the control circuit62shown inFIG.8.

As shown inFIG.12, the T-shaped flexible polymer sheet92may provide for a riser portion92aand a crossbar portion92bsized to allow the T-shape to be wrapped about and adhered to the outer surface of the cup34, with the crossbar portions92bcovering the outside three adjacent panels of the sidewalk40and the riser portion92acovering a bottom wall42and the remaining side wall40to conduct heat thereto. By placing temperature controlled heating in close proximity to each of the surfaces of the cups32only a thin film of water needs to be generated to release the ice cubes, greatly reducing energy usage.

Referring now toFIG.13, in an alternative embodiment the frame50may incorporate an induction coil102passing along the outer walk52of the frame50about axis36. This induction coil102may be driven at a high frequency by a AC power source104, for example, incorporated into control circuit62to create an oscillating magnetic field106passing upward (and downward) through multiple cups32contained in the frame50.

Referring now toFIG.14, this varying magnetic field106creates an eddy current108, for example, circulating in two directions in the bottom wall42creating heat through resistive loss that heats the bottom wall42and by conductive connection the sidewalk40. Together, the induction coil102, the power source104and the walls of the ice cup34form a heater72b.