US3648462A

US3648462A - Evaporator cover construction for an ice making apparatus

Info

Publication number: US3648462A
Application number: US39777A
Authority: US
Inventors: John B Lyman
Original assignee: Whirlpool Corp
Current assignee: King Seeley Thermos Co
Priority date: 1970-05-22
Filing date: 1970-05-22
Publication date: 1972-03-14
Anticipated expiration: 1989-03-14
Also published as: CA928092A; DE7119266U; FR2093551A5; JPS5138102B1

Abstract

A cover or cap assembly for an evaporator of an ice making apparatus has an inner cover member forming a collection chamber receiving ice flakes or slush and being composed of an elastomeric material or similar thermally insulative material having a substantially low thermal conductivity relative to thermally conductive, metallic material and forming a surface having improved lubricity relative to the ice flakes or slush moving through the collection chamber. An outer, rigid backing member composed of a thermally conductive maetallic material receives the inner cover in nested assembly, and the inner cover has integrally formed insulative barriers between the backing member and the contiguously disposed portions of the ice making apparatus.

Description

United States Patent Lyman [54] EVAPORATOR COVER CONSTRUCTION FOR AN ICE MAKING APPARATUS Inventor:

John B. Lyman, Bloomington, Minn.

Whirlpool Corporation, Benton Harbor, Mich.

May 22, 1970 Assignee:

Filed:

Appl. No.:

US. Cl ..62/354, 165/135 Int. Cl. ..Fc l/14 Field of Search ..l07/l4; 62/354, 320, 74,

[56] References Cited UNITED STATES PATENTS 3,008,434 11/1961 Maldari 107/14 2,428,995 10/1947 Rogers ..l00/l48 UX 3,196,624 7/1965 Reynolds ..62/7l [4 1 Mar. 14, 1972 FOREIGN PATENTS OR APPLICATIONS 409,499 5/1934 Great Britain ..62/354 Primary Examiner-William E. Wayner Attorney-James S. Nettleton, Thomas E. Turcotte, Burton H. Baker, Donald W. Thomas, Gene A. Heth, Franklin C. Harter, Anthony Niewyk, Robert L. Judd and Hill, Sherman, Meroni, Gross & Simpson [5 7] ABSTRACT A cover or cap assembly for an evaporator of an ice making apparatus has an inner cover member forming a collection chamber receiving ice flakes or slush and being composed of an elastomeric material or similar thermally insulative material having a substantially low thermal conductivity relative to thermally conductive, metallic material and forming a surface having improved lubricity relative to the ice flakes or slush moving through the collection chamber. An outer, rigid backing member composed of a thermally conductive maetallic material receives the inner cover in nested assembly, and the inner cover has integrally formed insulative barriers between the backing member and the c ontiguously disposed portions of the ice making apparatus.

10 Claims, 5 Drawing Figures PATENTEUMAR 14 I972 3, 648,462

sum 2 OF 3 liY PATENTEDMAR 14 I972 SHEET 3 [IF 3 EVAPORA'FOR COVER CONSTRUCTION FOR AN ICE MAKING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to ice makers and more particularly refers to a cover or cap assembly forming a collection chamber receiving ice flakes or slush harvested from a refrigerated surface.

2. Description of the Prior Art In one form of ice making apparatus, heretofore provided, ice products are produced by continuously harvesting and compressing ice flakes or slush which ice products were formed on a refrigerated, cylindrical wall portion provided by an upright, tubular evaporator having an internal refrigerated bore surface sized to cooperate with helical flights of a rotatable harvesting auger disposed in closely spaced relationship thereto. A cover or cap extends across an upper end of the evaporator and forms a collection chamber receiving the harvested ice flakes or slush and directing the same to suitable compression means for compressing the ice flakes or slush into a hard solidified product.

The ice flakes or slush may include ice particles, ice flakes and liquid water, at a temperature of about 32 F., whereas the evaporator bore surface is maintained at a temperature lower than 32 F. so that a film of ice forms thereon. The covers or caps generally utilized heretofore were cooled by contact with refrigerated portions of the evaporator, thereby causing formation of an ice film on wall surfaces of the collection chamber. Also, those covers were generally composed of a material which was wetted by water, thereby permitting the ice film to adhere to the collection chamber wall surfaces and buildup thereon thereby increasing the possibility of the collection chamber becoming clogged with an accumulation of ice and requiring shutdown periods for thawing out the apparatus.

SUMMARY OF THE INVENTION A cap or cover assembly, constructed in accordance with the principles of the present invention, for forming a collection chamber on an ice making apparatus, includes an inner cover member having collection channels formed therein and being composed of an elastomeric or similar thermally insulative material and an outer, rigid backing member receiving the inner cover in nested assembly and providing the required structural strength for supporting superjacently disposed portions of the ice making apparatus.

The elastomeric or similar material has a thermal conductivity substantially lower than that of the outer backing member, which may advantageously be composed of a thermally conductive metallic material, such as sheet-form or cast stainless steel. While the metal backing member may be cooled, due to its proximity to refrigerated portions of the evaporator, to a temperature below the freezing point of water, i.e., 32 F walls of the collection chamber formed by the inner cover are maintained, due to its substantially lower thermal conductivity, at a temperature above the freezing point. Thus, ice will not be formed on the walls of the collection chamber.

In order to implement flow of the ice flakes or slush through the collection chamber, the inner cover is composed of a material having low thermal conductivity which is not wetted by water and thus presents a substantially frictionless or selflubricated surface on the collection chamber walls.

The inner cover member has a configuration relative to the outer backing member for forming integral portions interposed between the backing member and refrigerated portions of the evaporator and between the backing member and superjacently disposed nozzle means for compressing the ice product into a hard form. Thus insulative barriers are formed at opposite ends of the backing member. A plurality of annular sealing ridges abut an upper surface of a support flange on the evaporator for forming a labyrinth seal to prevent leakage of water between the cover assembly and the evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view with portions broken away to illustrate additional details of an ice making apparatus having an evaporator cover assembly constructed in accordance with the principles of the present invention;

FIG. 2 is an enlarged, partial sectional view, with parts omitted for clarity, of the ice making apparatus shown in FIG. l and illustrates the cover assembly of the present invention;

FIG. 3 is a bottom plan view of an inner cover member of a cover assembly of the present invention;

FIG. 4 is an enlarged, sectional view of a portion of the inner cover member of the present invention and illustrates an insulating flange and sealing ridges; and

FIG. 5 is a top plan view of the cover assembly of the present invention with portions broken away to illustrate additional details.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, an ice maker of the present invention is shown generally at 10 and includes an evaporator unit 11 having an internal bore forming a cylindrical wall 12. An integrally formed evaporator passageway 13 has a refrigerant or coolant expanded thereinto by a refrigeration system through an expansion valve or other pressure reducing means. Water is introduced into the evaporator internally of the wall 12 through an inlet conduit 15 disposed near a base of the unit 11. The water tends to freeze on the wall 12 in the form of a thin film of ice. One or more helical flights 16 formed or carried on a rotating harvesting auger l7 cooperate with the wall 12, which, in effect, forms a freezing surface 14, whereby thin films of ice formed on. the freezing surface 14 will be continuously harvested. The auger 17 progressively advances a mixture of ice particles, including slush and chunks upwardly in the unit 11 towards a collection chamber I8 superjacent the evaporator unit 11.

Suitable fastening means, such as bolts 19, attach a radially outwardly extending flange 21' formed on the evaporator unit 11 to a drive housing 22. A shaft 23 is disposed centrally of the evaporator unit ll and has a lower end portion supported within axially spaced bearing means in the drive housing 22. Gear reduction means are driven by a prime mover such as an electric motor M. The shaft 23 is dlisposed coaxially of the evaporator bore and has a driven connection with the gear reduction means. Water is prevented! from entering the drive housing 22 by seal means including a shaft seal 24 engaging the shaft 23.

The harvesting auger 17 includes a central hub portion 26 having a throughbore. A threaded portion 27 of the bore receives an upper threaded end portion 28 of the shaft 23 to support the harvesting auger 17 for corotation with the driven shaft 23. A cylindrical portion 29 formed on the harvesting auger 17 and spaced concentrically inwardly of the refrigerated, freezing surface 14 has an outer diameter relatively larger than a diameter of the shaft 23 and carries the helically extending flights or blades 16, which have edges 30 closely spaced adjacent the surface 14 to harvest the thin fllm of ice as the harvesting auger 17 rotates relative to the surface 14.

The collection chamber 18 is formed by a generally circular or inverted cupshaped cap means generally indicated at 3! and having a plurality of channels 32 receiving the ice flake product from the harvesting auger 17. Each of the channels 32 extends in a generally spiral path of increasing cross-section for conducting the flake ice product discharged from the evaporator unit II upwardly into a central passageway 33 leading into an internal bore 34 of a compression and forming nozzle 35. The nozzle 35 has a generally outwardly extending flange 36 secured to the cap means .31 by suitable fasteners, such as nut and bolt assemblies as at 37 and the cap means 31 are suitably secured by a plurality of circumferentially spaced bolts 38 to a radially outwardly extending flange 39 on the evaporator unit. Thus, the drive housing 22, the evaporator 11, the cap means 31 and the compression nozzle 35 are detachably secured in a stacked relationship by the fastening means 19, 37 and 38.

In order to compress the flake ice product harvested from the refrigerated freezing surface 14 into a solid ice product, a compression auger 41 mounted for corotation with the harvesting auger 17 receives the flake ice product from the collection chamber 18 and squeezes the ice particles through the nozzle bore 34 to remove excess water and form an emergent solid column of ice at an upper end 42 of the nozzle 35. The

compression auger 41 has a depending, threaded stud 43 engaged into the threaded bore 27 of the harvesting auger.

If desired, appropriately configured extrusion means may be attached to an outwardly extending flange 44 at the upper end 42 of the nozzle 35 for forming the emerging, solid column of ice into a desired configuration. The extrusion means may be designed to transversely shear the emerging column of ice into ice cubes or otherwise shape the column into desired configurations, for example, chipped ice, shaved ice, cracked ice or small ice cubes.

In accordance with the principles of the present invention, the cap means or cover assembly 31 includes an inner cover member 51 having the collection channels 32 and the central passageway 33 formed therein and an outer backing member 52 receiving the inner member in nested assembly therewith. In order to retard the formation and accumulation of ice within the collection channels 32, the inner cover 51 is composed of an elastomeric or similar plastic or rubber like material having a substantially lower thermal conductivity than that of a metallic material from which the outer backing S2 is constructed.

Thermal conductivity is defined as the quantity of heat usually expressed in BTUs that flows in a unit of time through a unit area of plate of unit thickness having a unit difference of temperature between its fuses. Metals usually have high thermal conductivity, steel for example, have a K of 12-30 at a temperature range of 60 to 600 F. Insulator material such as rubber or plastic will be less than O.l at 100 F. The plastic material used to make the inner cover member should preferably have a thermal conductivity of less than 0.1 at 100 F.

The ice flakes or slush advanced by the harvesting auger into the channels 32 includes ice particles, chunks, ice flakes and liquid water is at a temperature of about 32 F whereas the refrigerated wall portions 12 of the evaporator 11 disposed immediately subjacent of the cap means 31 are maintained at a temperature below 32 F. to promote the formation of ice on the freezing surface 14. Due to the lower thermal conductivity of the inner cover 51, the collection chamber wall surfaces are not cooled below the freezing point of water, thereby retarding the formation and accumulation of ice on those wall surfaces.

The accumulation of ice within the collection channels 32 is further retarded by composing the inner cover 51 of a material which is not wetted by water so that ice particles and ice flakes will not adhere to the collection channel wall surfaces. In such a manner, the inner cover 51 forms the collection channel 32 with substantially frictionless or self-lubricating surfaces, thereby implementing the passage of the ice flakes or slush through the channels under the influence of a driving force created by rotation of the harvesting auger 17 and the compression auger 41.

The outer backing member 52 is advantageously constructed of a rigid metallic material having sufficient strength for supporting the superjacent nozzle means 35 and also having a higher thermal conductivity than that of the material of the inner cover 51. Advantageously, the outer backing member 52 may be constructed of sheet-form stainless steel, which has the additional features of corrosion resistance.

As one example of the cap means 31 of the present invention, the formation and accumulation of ice within the collection channels 32 does not occur when the inner cover 51 includes a molded part composed of a rubber and latex composition having a Durometer hardness in the order of 80, and when the backing member 52 includes a part stamped or otherwise formed of stainless steel. The thermal conductivity of the rubber and latex composition, expressed in terms of the quantity of heat in calories which is transmitted per second through a plate 1 centimeter thick across an area of I square centimeter for a temperature difference of 1 C., is approximately 0.0005. In comparison, the thermal conductivity of stainless steel is approximately 0.l l. A specific example of the rubber and latex composition is sold by AKU-Goodrich, Holland, under the trade name No. 1072 l-Iycar. That material is an odorless, tasteless material approved by the Food and Drug Administration for use with potable water.

As illustrated in the drawings, the inner cover 51 has a circular, inverted, cup-shaped central body portion 53 sized to extend across and cover the evaporator bore formed by the cylindrical wall 12. The body portion 53 has an outer boundary including a planar top wall 54 and a substantially cylindrical sidewall 56 joined to the top wall by an arcuately chamfered comer edge 57.

Each of the collection channels 32, formed in the inner cover body 53, has a pair of equally spaced

sidewalls

58, 58 and a bight portion 59 joining the sidewalls and arranged relative thereto for forming the channels 32 with a U-shaped cross section. The equally spaced

sidewalls

58, 58 extend from a periphery 61 of the inner cover body portion 53 in a generally spiral path and open laterally into the central passage 33 formed centrally of the body portion. The spirally extending channels 32 collect the ice flakes or slush advanced by the harvesting auger l7 and direct the ice product upwardly through the central passage 33 and into the nozzle bore 34. The bight portion 59 is axially outwardly inclined in a manner to form the collection channels 32 with a cross section progressively increasing in area in the direction of ice product movement.

An annular, central web portion 63 of the backing member 52 received the inner cover body portion 53 in nested relationship and is characterized by a generally arcuately shaped transverse cross section formed complementally to the arcuate chamfered edge 57. A top wall 64, axially offset from the central web 63 extends parallel to the cover top wall portion 54 and has a lower surface 66 spaced from the cover top wall to form an annular space 67 therebetween. A plurality of circumferentially spaced apertures 68 extend through the top wall 64 of the backing member and intersect the annular space 67, thereby forming a plurality of bolt holes for receiving an equal number of the nut and bolt assemblies 37. Each of the nut and bolt assemblies 37 has a bolt 69 including a bolt head 71 disposed in the annular space 67 and welded or otherwise retained against rotation in a manner to facilitate assembly of the noule means 35 with the cap means 31.

In order to close an inwardly opening end of the space 67 and to insulate the backing member top wall 64 from the ice product driven through the central passage 33, the inner cover 51 has an upstanding, hollow neck 72 extending upwardly beyond terminal ends 73 of the backing member top wall 64. The terminal ends 73 are arranged to form an aperture closely receiving the cover neck 72.

An out-turned flange 74 extending outwardly of an upper end of the neck 72 forms a laterally opening channel 75 receiving the terminal ends 74 and overlaps the backing member top wall 64, thereby forming an insulative barrier integral with the inner cover for isolating the margin portion from the ice and for insulating the margin portions from the superjacent nozzle 35. A recess 77 in the nozzle 35 receives the out-turned flange 74, and, if desired, a liner 78 formed in the nozzle throughbore 34 may have a foot portion 79 abutting the out-turned flange in sealing engagement therewith.

The cover neck 72 has internal walls 81 forming an upward extension of the central passage 33 to innerconnect the nozzle throughbore 34 with the central passage 33. In order to retard rotation of the ice product as the compression auger 41 rotates, the nozzle bore 34 may have a noncircular configuration in transverse cross section, the central passage 33 may have a configuration complemental to the nozzle bore configuration. As illustrated in the drawings, the transverse cross sectional configuration of the nozzle bore 34, and thus the central passage 33, may be in the form of a square.

It is also contemplated by the present invention to configure the inner cover 51 with an integral portion interposed between the radially outwardly extending support flange 39 and the evaporator unit 11 and the outer backing member 52, thereby forming an insulative barrier. Thus, the inner cover 511 has a radially outwardly extending base flange 82 formed around the periphery 61 of the central body portion 53. An underneath surface 83 of the base flange 82 overlaps and abuts an upper surface 84 of the evaporator flange 39. An annular attachment flange 86 on the outer backing member 52 extends radially outwardly of the central web 63 and overlaps the base flange 82. Thus, the attachment flange 36, the base flange 82 and the support flange 39 are stacked in laminar adjacency with the cover base flange forming an insulative barrier between the other two flanges.

A plurality of circumferentially spaced clearance apertures 87 are formed in the attachment flange 86 in registry with an equal number of tapped holes 88 in the evaporator flange 39 and with an equal number of notches 91 extending inwardly of a periphery 92 of the cover flange 83. The attachment bolts 38 pass through the clearance apertures 97 and the notches 98 and threadingly engage into the tapped holes 89, thereby detachably clamping the backing member 52, the inner cover 51 and the evaporator 11 in firm assembly. A depending, peripheral lip 93 formed on the outer backing member 52 pilots on an outer cylindrical end 94 of the evaporator support flange 39 to center the cap means 31 on the evaporator llll.

Sealing means for preventing the leakage of water outwardly between the cap means 31 and the evaporator 11 include a plurality of concentric, radially spaced, circular sealing ridges 96 integrally formed on the inner cover 51, as illustrated in detail in FIG. 4. The sealing ridges 96 depend from the underneath surface 83 of the inner cover base flange 82 and have a V-shaped configuration in transverse cross section. When the cap means 31 are clamped in firm assembly with the evaporator ill, the sealing ridges 96 abut the upper surface 84 of the evaporator flange 39 and are slightly compressed in a manner to form a labyrinth seal between the cover base flange and the evaporator flange.

Although those versed in the art may suggest various minor modifications, it should be understood that I wish to incorporate within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

ll. In an ice maker, means forming an evaporator unit having an internal, refrigerated cylindrical surface forming an internal bore;

auger means rotatable within said evaporator bore and hav ing flights in close proximity to said refrigerated surface for harvesting and axially upwardly advancing an ice flake product frozen on said surface;

collection means receiving the ice product harvested by said auger, said collection means comprising an inner cover member having a central passageway and a central, circular, inverted cup-shaped body portion sized to extend across and close an upper end of said evaporator bore, said body portion forming a collection chamber receiving the ice flake product upwardly advanced by said-auger means, and directing and mechanically transferring the ice flake product to said passageway; and

an outer backing member having said cover nested therein and clamping said cover to subjacent portions of an ice maker,

said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member,

whereby the mechanical transfer of ice through said collection chamber is enhanced.

2. In an ice maker as defined in claim 1 and further characterized by said cover material being an elastomeric material forming a non-wettable surface, thereby retarding adhesion of the ice flake product to surfaces of said cover.

3. In an ice maker as defined in claim 2 and further characterized by:

said cover being composed of a rubber and latex composition; and

said outer backing member being constructed of sheet-form stainless steel.

4. In an ice maker as defined in claim 1 and further characterized by means integral with said cover and forming insulative barriers between said backing member and portions of an ice maker disposed contiguously of said cover.

5. In an ice maker,

means forming an evaporator unit having an internal,

refrigerated cylindrical surface forming an internal bore;

an inner cover member having a central passageway and a collection chamber receiving ice flake product and directing the same to said passageway; and

said cover having a central, circular, inverted cup-shaped body portion sized to extend across and close said evaporator bore;

said cover body portion having a plurality of collection channels formed therein and extending from a periphery thereof and to said central passage in a generally spiral path; and

said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member.

6. In an ice maker,

means forming an evaporator unit having an internal,

refrigerated cylindrical surface forming an internal bore; said evaporator having a radially outwardly extending support flange formed at an upper end portion;

said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member;

said backing member having an annular attachment flange sized complementally to said support flange;

said cover having a radially outwardly extending base flange formed integral therewith and interposed between said support flange and said attachment flange in laminar adjacency thereto; and

attachment means securing said attachment flange to said support flange for clamping said backing member, said cover and said evaporator in firm assembly, whereby said cover base flange forms an insulative barrier between refrigerated portions of said evaporator and said backing member.

7. In an ice maker as defined in claim 6 and further characterized by a plurality of concentric, radially spaced, depending sealing ridges formed integrally on said cover base flange and sealingly abutting an upwardly projecting surface of said support flange for forming a labyrinth seal between said cover and said evaporator.

8. In an ice maker,

means forming an evaporator unit having an internal,

refrigerated cylindrical surface forming an internal bore;

said cover having a central, circular, inverted cup-shaped body portion sized to extend across and close said evaporator bore; said cover having an upstanding neck formed integral with said body portion and having an out-turned flange forming a laterally opening channel; an outer backing member having said cover nested therein and clamping said cover to subjacent portions of an ice maker, said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member; said backing member having an annular top wall overlying said cover body portion and having inner terminal ends received in said laterally opening channel and forming an aperture closely receiving said upstanding neck. 9. In an ice maker, means forming an evaporator unit having an internal refrigerated cylindrical surface forming an internal bore; ice collection means comprising a cover member composed of a thermally insulative material and having a central passageway and a collection chamber receiving an ice flake product from said evaporator and directing the product to said central passageway;

said cover having a central body portion sized and configured to extend across and close and end of said evaporator bore; said cover body portion having a plurality of collection channels therein forming said collection chamber and extending from a periphery of said body portion and to said central passageway in a generally spiral path for mechanically transferring the ice flake product received from the evaporator to said central passageway, with the thermally insulative material on the wall surfaces of said collection channels acting to enhance the mechanical transfer of ice product to said central passageway. 10. In an ice maker as defined in claim 9 and further characterized by:

attachment means securing said base flange to said support flange.

Claims

1. In an ice maker, means forming an evaporator unit having an internal, refrigerated cylindrical surface forming an internal bore; auger means rotatable within said evaporator bore and having flights in close proximity to said refrigerated surface for harvesting and axially upwardly advancing an ice flake product frozen on said surface; collection means receiving the ice product harvested by said auger, said collection means comprising an inner cover member having a central passageway and a central, circular, inverted cup-shaped body portion sized to extend across and close an upper end of said evaporator bore, said body portion forming a collection chamber receiving the ice flake product upwardly advanced by said auger means, and directing and mechanically transferring the ice flake product to said passageway; and an outer backing member having said cover nested therein and clamping said cover to subjacent portions of an ice maker, said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member, whereby the mechanical transfer of ice through said collection chamber is enhanced.

3. In an ice maker as defined in claim 2 and further characterized by: said cover being composed of a rubber and latex composition; and said outer backing member being constructed of sheet-form stainless steel.

4. In an ice maker as defined in claim 1 and further characterized by means integral with said cover and forming insulative barriers between said backing member and portions of an ice maker disposed contiguously of said cover. 5. In an ice maker, means forming an evaporator unit having an internal, refrigerated cylindrical surface forming an internal bore; an inner cover member having a central passageway and a collection chamber receiving ice flake product and directing the same to said passageway; and said cover having a central, circular, inverted cup-shaped body portion sized to extend across and close said evaporator bore; said cover body portion having a plurality of collection channels formed therein and extending from a periphery thereof and to said central passage in a generally spiral path; and an outer backing member having said cover nested therein and clamping said cover to subjacent portions of an ice maker, said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member.

6. In an ice maker, means forming an evaporator unit having an internal, refrigerated cylindrical surface forming an internal bore; said evaporator having a radially outwardly exteNding support flange formed at an upper end portion; an inner cover member having a central passageway and a collection chamber receiving ice flake product and directing the same to said passageway; and an outer backing member having said cover nested therein and clamping said cover to subjacent portions of an ice maker, said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member; said backing member having an annular attachment flange sized complementally to said support flange; said cover having a radially outwardly extending base flange formed integral therewith and interposed between said support flange and said attachment flange in laminar adjacency thereto; and attachment means securing said attachment flange to said support flange for clamping said backing member, said cover and said evaporator in firm assembly, whereby said cover base flange forms an insulative barrier between refrigerated portions of said evaporator and said backing member.

8. In an ice maker, means forming an evaporator unit having an internal, refrigerated cylindrical surface forming an internal bore; an inner cover member having a central passageway and a collection chamber receiving ice flake product and directing the same to said passageway; and said cover having a central, circular, inverted cup-shaped body portion sized to extend across and close said evaporator bore; said cover having an upstanding neck formed integral with said body portion and having an out-turned flange forming a laterally opening channel; an outer backing member having said cover nested therein and clamping said cover to subjacent portions of an ice maker, said cover being composed of a thermally insulative material having a lower thermal conductivity than that of material forming said outer backing member; said backing member having an annular top wall overlying said cover body portion and having inner terminal ends received in said laterally opening channel and forming an aperture closely receiving said upstanding neck.

9. In an ice maker, means forming an evaporator unit having an internal refrigerated cylindrical surface forming an internal bore; ice collection means comprising a cover member composed of a thermally insulative material and having a central passageway and a collection chamber receiving an ice flake product from said evaporator and directing the product to said central passageway; said cover having a central body portion sized and configured to extend across and close and end of said evaporator bore; said cover body portion having a plurality of collection channels therein forming said collection chamber and extending from a periphery of said body portion and to said central passageway in a generally spiral path for mechanically transferring the ice flake product received from the evaporator to said central passageway, with the thermally insulative material on the wall surfaces of said collection channels acting to enhance the mechanical transfer of ice product to said central passageway.

10. In an ice maker as defined in claim 9 and further characterized by: said evaporator having a radially outwardly extending support flange formed at an upper end portion thereof; said cover having a base flange extending radially outwardly of said body portion and formed integrally therewith, said base flange being disposed in laminar adjacency with said support flange; and attachment means securing said base flange to said support flange.