Method and apparatus for making clear ice

Claim 2

A clear ice maker comprising tray means adapted to contain a body of water and having an open top, a grid in said tray means for supporting clear ice to be formed thereon and having a poor heat conducting characteristic, said tray means adapted to provide the lower portion of said body of water with an abovefreezing temperature to maintain it in a liquid state, refrigerating means adapted to expose the surface of said body of water at said open top to below-freezing ambient air for a sufficient period to start the freezing of a surface layer of ice on said body of water and to continue the freezing thereof progressively downwardly in supporting engagement with said grid, and means adapted to remove said grid and the ice supported by said grid from said tray means before said ice extends to the bottom of said tray means.

Claim 3

A clear ice maker comprising tray means adapted to contain a volume of water in a refrigerated ambient, a grid in said tray means for supporting clear ice to be formed thereon and having a poor heat conducting characteristic, said grid on the inside thereof having a cube forming cavity defining the top surface of said volume of water with said refrigerated ambient, heating means adapted to provide the lower portion of said volume of water with an above-freezing temperature to maintain it in a liquid state, refrigerating means adapted to expose said volume of water to below-freezing ambient air along said top surface for a sufficient period to start freezing a surface layer of ice on said volume of water in said cube forming cavity and to continue the freezing thereof progressively downwardly in supporting engagement with said grid, means adapted to periodically automatically remove said grid and the ice supported by said grid from said tray means before said ice extends to the bottom of said tray means, and means connected to the bottom of said tray means for supplying make-up water to said tray means during the periodic removal of said ice to restore said volume of water to the volume contained in said tray means before the freezing of said surface layer of ice was started.

Claim 4

A clear ice maker comprising tray means adapted to contain a volume of water in a refrigerated ambient, a grid in said tray means for supporting clear ice to be formed thereon and having a poor heat conducting characteristic, said grid on the inside thereof having a cube forming cavity defining the top surface of said volume of water with said refrigerated ambient, heating means adapted to provide the lower portion of said volume of water with an above-freezing temperature to maintain it in a liquid state, refrigerating means adapted to expose said volume of water to below-freezing ambient air along said top surface for a sufficient period to start freezing a surface layer of ice on said volume of water in said cube forming cavity and to continue the freezing thereof progressively downwardly in supporting engagement with said grid, means adapted to periodically automatically remove said grid and the ice supported by said grid from said tray means before said ice extends to the bottom of said tray means, and means connected to the bottom of said tray means for supplying make-up water to said tray means during the periodic removal of said ice to restore said volume of water to the volume contained in said tray means before the freezing of said surface layer of ice was started.

Claim 9

A clear ice maker comprising a grid in a tray adapted to contain water, means for exposing the bottom side of said tray to above-freezing temperatures whereby to retain a lower portion of water in said tray in a liquid state, means exposing the top surface of water in said tray to below-freezing temperatures for a sufficient period to start the freezing of a portion of said water from said top surface down into clear ice, said grid on the inside thereof having a cube forming cavity defining the top surface of said water and on the outside thereof a void formed by said cavity, said void filled sufficiently with filler material to displace substantially all of the water from the tray into the cavity, said filler material having an anti-stick characteristic with respect to ice and said tray to provide easy removal of the grid and clear ice from the tray, means for periodically removing the grid and clear ice from said tray before the clear ice extends a sufficient distance toward the bottom side of said tray to entrap gas and minerals which may be entrained in said water, and means for releasing said clear ice from said grid.

Claim 10

A clear ice maker comprising a grid in a tray adapted to contain water, means for exposing the bottom side of said tray to above-freezing temperatures whereby to retain a lower portion of water in said tray in a liquid state, means exposing the top surface of water in said tray to below-freezing temperatures for a sufficient period to start the freezing of a portion of said water from said top surface down into clear ice, said grid on the inside thereof having a cube forming cavity defining the top surface of said water and on the outside thereof a void formed by said cavity, said void filled sufficiently with filler material to displace substantially all of the water from the tray into the cavity, said filler material having an anti-stick characteristic with respect to ice and said tray to provide easy removal of the grid and clear ice from the tray, means for periodically removing the grid and clear ice from said tray before the clear ice extends a sufficient distance toward the bottom side of said tray to entrap gas and minerals which may be entrained in said water, and means for releasing said clear ice from said grid.

Claim 11

A clear ice maker comprising a warpable grid in a tray adapted to contain water, heating means for heating the bottom side of said tray to above-freezing temperatures to retain a lower portion of water in said tray in a liquid state throughout the clear ice making process, fan means distributing sub-freezing air over a top planar surface of water in said tray for a sufficient period to initiate the freezing of clear ice along the interface between said air and said top planar surface and to continue the freezing of clear ice downwardly in said grid, said grid on the inside thereof having cube forming cavities of inverted truncated pyramidal shape defining in an upper portion of said cavities the top surface of water in said tray and on the outside thereof voids formed by said cavities, said voids filled sufficiently with filler material to displace substantially all of any water in the tray from the tray into the cavities, said filler material and said grid having an anti-stick characteristic with respect to ice and said tray to provide easy removal of the grid and clear ice cubes from the tray and the clear ice cubes from said grid, means for periodically removing the grid and clear ice cubes from said tray before the freezing of clear ice downwardly reaches said lower portion of water in said tray and entraps in said cubes any gas and minerals which may be entrained in said lower portion of water, and means for warping said grid to release said clear ice cubes therefrom, said filler material having a characteristic of flexibility to distribute forces uniformly throughout said grid when the grid is removed from the tray and warped to release the clear ice cubes.

Claim 12

A clear ice maker comprising a warpable grid in a tray adapted to contain water, heating means for heating the bottom side of said tray to above-freezing temperatures to retain a lower portion of water in said tray in a liquid state throughout the clear ice making process, fan means distributing sub-freezing air over a top planar surface of water in said tray for a sufficient period to initiate the freezing of clear ice along the interface between said air and said top planar surface and to continue the freezing of clear ice downwardly in said grid, said grid on the inside thereof having cube forming cavities of inverted truncated pyramidal shape defining in an upper portion of said cavities the top surface of water in said tray and on the outside thereof voids formed by said cavities, said voids filled sufficiently with filler material to displace substantially all of any water in the tray from the tray into the cavities, said filler material and said grid having an anti-stick characteristic with respect to ice and said tray to provide easy removal of the grid and clear ice cubes from the tray and the clear ice cubes from said grid, means for periodically removing the grid and clear ice cubes from said tray before the freezing of clear ice downwardly reaches said lower portion of water in said tray and entraps in said cubes any gas and minerals which may be entrained in said lower portion of water, and means for warping said grid to release said clear ice cubes therefrom, said filler material having a characteristic of flexibility to distribute forces uniformly throughout said grid when the grid is removed from the tray and warped to release the clear ice cubes.

Claim 13

The clear ice maker of claim 6 wherein said grid is polypropylene and said filler material is RTV silicone rubber.

Claim 14

The clear ice maker of claim 6 wherein the top surface of water adapted for freezing as clear ice is at least 65 square inches, said fan means is distributing air having a sub-freezing temperature of substantially minus 10* F. to minus 12* F. at substantially 10 to 15 cubic feet per minute, and said removing means includes a timer controlling the removal of the grid and clear ice cubes from said tray substantially once every two and one-half hours.

Claim 15

In combination, a domestic freezer, a clear ice maker in said freezer comprising a warpable grid in a tray adapted to contain water, heating means energizable for heating the bottom side of said tray to above-freezing temperatures to retain a lower portion of water in said tray in a liquid state throughout the clear ice making process, fan means operable for cooling said freezer to substantially 0* F. and for distributing sub-freezing air at substantially minus 10* F. to minus 12* F. over a top planar surface of water in said tray for a sufficient period to initiate the freezing of clear ice along the interface between said air and said top planar surface and to continue the freezing of clear ice downwardly in said grid, said grid on the inside thereof having a cube forming cavity defining in an upper portion of said cavity the top surface of water in said tray and on the outside thereof a void formed by said cavity, said void filled sufficiently with filler material to displace substantially all of any water in the tray from the tray into the cavity, and control means deenergizing said heating means when said fan means is not operating for distributing said sub-freezing air to reduce heat dissipated in said freezer.

Claim 16

In combination, a domestic freezer, a clear ice maker in said freezer comprising a warpable grid in a tray adapted to contain water, heating means energizable for heating the bottom side of said tray to above-freezing temperatures to retain a lower portion of water in said tray in a liquid state throughout the clear ice making process, fan means operable for cooling said freezer to substantially 0* F. and for distributing sub-freezing air at substantially minus 10* F. to minus 12* F. over a top planar surface of water in said tray for a sufficient period to initiate the freezing of clear ice along the interface between said air and said top planar surface and to continue the freezing of clear ice downwardly in said grid, said grid on the inside thereof having a cube forming cavity defining in an upper portion of said cavity the top surface of water in said tray and on the outside thereof a void formed by said cavity, said void filled sufficiently with filler material to displace substantially all of any water in the tray from the tray into the cavity, and control means deenergizing said heating means when said fan means is not operating for distributing said sub-freezing air to reduce heat dissipated in said freezer.

Claim 17

A clear ice maker in a freezer comprising a tray having side and bottom walls adapted to contain a body of water, a grid in said tray having cavity-forming means for displacing the body of water contained by said walls into the cavity, fan means distributing sub-freezing air over the top planar surface of said body of water in said grid cavity for a sufficient period to initiate the freezing of clear ice in said grid cavity along the interface between said air and said top planar surface and to continue the freezing of clear ice downwardly in said grid cavity, and a bucket for storing said clear ice in said freezer and being removable from said freezer, heating means energizable to maintain said body of water in a liquid state adjacent said tray below the freezing clear ice, harvesting mechanism for removing said grid and clear ice from said tray before the freezing of clear ice downwardly in said grid cavity reaches the bottom wall of said tray and depositing said clear ice in said bucket, said heating means comprising a first heater for the sidewall of the tray and a second heater for the bottom wall of the tray, and control means providing for continuous energization of said first heater and energization of said second heater only when said bucket is full of clear ice or removed from said freezer whereby to maintain said body of water below the freezing clear ice at substantially 36* F.

Claim 18

A clear ice maker in a freezer comprising a tray having side and bottom walls adapted to contain a body of water, a grid in said tray having cavity-forming means for displacing the body of water contained by said walls into the cavity, fan means distributing sub-freezing air over the top planar surface of said body of water in said grid cavity for a sufficient period to initiate the freezing of clear ice in said grid cavity along the interface between said air and said top planar surface and to continue the freezing of clear ice downwardly in said grid cavity, and a bucket for storing said clear ice in said freezer and being removable from said freezer, heating means energizable to maintain said body of water in a liquid state adjacent said tray below the freezing clear ice, harvesting mechanism for removing said grid and clear ice from said tray before the freezing of clear ice downwardly in said grid cavity reaches the bottom wall of said tray and depositing said clear ice in said bucket, said heating means comprising a first heater for the sidewall of the tray and a second heater for the bottom wall of the tray, and control means providing for continuous energization of said first heater and energization of said second heater only when said bucket is full of clear ice or removed from said freezer whereby to maintain said body of water below the freezing clear ice at substantially 36* F.

Claim 19

The clear ice maker of claim 10 wherein said first and second heaters are vinyl covered resistance wire retained in a foil sandwich between said side and bottom walls of the tray on the outside thereof and a layer of foam insulation.

Claim 20

In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, a clear ice maker in said freezer compartment, said clear ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the top surface of water contained in said tray at said predetermined level for a sufficient period to start freezing an upper portion of said water from said top surface downwardly into clear ice, heating means maintaining a bottom portion of said water in a liquid state adjacent said bottom tray wall, and water fill means for refilling said tray with water to said predetermined level when the upper clear ice portion is removed from said tray, said fill means including a reservoir adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said reservoir at said predetermined level, said reservoir being on the outside of said insulated cabinet wall substantially in the same horizontal plane as said tray, and conduit means interconnecting said reservoir and said tray from connections with said reservoir and tray below said predetermined level to place said reservoir in liquid flow communication with the bottom portion of water in the tray whereby water is supplied from said reservoir to said tray through said conduit means until the water level in said tray and reservoir is common at said predetermined level.

Claim 21

In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, a clear ice maker in said freezer compartment, said clear ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the top surface of water contained in said tray at said predetermined level for a sufficient period to start freezing an upper portion of said water from said top surface downwardly into clear ice, heating means maintaining a bottom portion of said water in a liquid state adjacent said bottom tray wall, and water fill means for refilling said tray with water to said predetermined level when the upper clear ice portion is removed from said tray, said fill means including a reservoir adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said reservoir at said predetermined level, said reservoir being on the outside of said insulated cabinet wall substantially in the same horizontal plane as said tray, and conduit means interconnecting said reservoir and said tray from connections with said reservoir and tray below said predetermined level to place said reservoir in liquid flow communication with the bottom portion of water in the tray whereby water is supplied from said reservoir to said tray through said conduit means until the water level in said tray and reservoir is common at said predetermined level.

Claim 22

The combination of claim 12 wherein the connection of said conduit means with said tray is in heat transfer relationship with said heating means whereby water in the conduit means on the inside of said insulated cabinet wall remains in a liquid state.

Claim 23

The combination of claim 12 wherein the heating means and the connection of said conduit means with said tray are foamed in place by insulation on the outside of said tray walls.