US20030159459A1

US20030159459A1 - Auger-type ice making apparatus with improved evaporator

Info

Publication number: US20030159459A1
Application number: US10/085,280
Authority: US
Inventors: Roger Brunner
Original assignee: Follett LLC
Current assignee: Follett LLC
Priority date: 2002-02-28
Filing date: 2002-02-28
Publication date: 2003-08-28

Abstract

An improved evaporator is provided for an ice making apparatus of the auger-type. The evaporator employs an evaporator body having spiral grooves cut or milled into its outer cylindrical surface and a cylindrical jacket disposed over the spiral groove formed on the outer cylindrical surface of the evaporator body, with the jacket being in interference-fit engagement against the groove of the evaporator body. The interference fit is formed by thermal expansion of the jacket prior to it being telescopically slid over the body, followed by a cooling-down of the jacket, by which it shrinks or compresses radially inwardly, to tightly seal against the outer periphery of the grooves, creating a sealed path for refrigerant flow, from inlet to outlet of the evaporator.

Description

BACKGROUND OF THE INVENTION

This invention relates to auger-type ice making machines used in a commercial setting, which produce flaked or chipped ice. Ice is formed by water freezing on the inner wall of a hollow cylindrical freezing chamber. A rotatable ice auger, sized to enable the scraping of ice off the inner surface of the freezing chamber conveys the flaked ice toward an axial end of the freezing chamber whereby the flaked ice is compressed into a rigid mass of ice which is subsequently severed into discrete, generally uniform chunks of ice.

The present invention is directed toward a new and improved auger-type ice making machine which has an improved evaporator.

The present invention is an improvement upon U.S. Pat. No. 5,394,708, the complete disclosure of which is herein incorporated by reference.

SUMMARY OF THE INVENTION

This invention relates to an auger-type ice making apparatus of the type wherein ice is produced on the inner walls of a cylindrical freezing chamber. A rotatable ice auger scrapes such walls producing flaked ice.

In accordance with the present invention, the evaporator of the auger-type ice making machine comprises a cylinder comprising an evaporator body of significant wall thickness, which has a continuous spiral groove cut (preferably milled) on its outer cylindrical surface. This spiral groove embodies the refrigerant flow canal. A second cylinder comprises a jacket which is placed around the evaporator body. The jacket has an interference fit around the body and can only be slid into place after it is thermally expanded. Once the jacket has been expanded and slid into place, it is cooled and, upon being cooled, undergoes a radial contraction, whereby the inner cylindrical surface of the jacket seals tightly against the outer diameter of the spiral groove of the evaporator body, such that refrigerant will flow only along the spiral groove, confined outwardly of the spiral groove by the inner cylindrical surface of the jacket. Refrigerant inlet and discharge ports are provided through the jacket.

This invention relates generally to an auger-type ice making apparatus where flaked ice is created on the interior wall of a cylindrical freezing chamber, scraped of the wall by an ice auger, and transferred out of the chamber, through a discharge aperture, to a discharge line.

It is accordingly a general object of the present invention to provide a new and improved auger-type ice making apparatus, with an improved evaporator.

It is another object of the present invention to provide a new and improved auger-type ice making apparatus which comprises an evaporator body having spiral grooves in its outer cylindrical surface, which grooves, together with the inner cylindrical surface of a jacket that is first heated or otherwise thermally expanded, and then allowed to cool, shrinks radially inwardly to form an interference fit against the continuous spiral groove, such that refrigerant delivered into and out of the spiral groove is confined between the evaporator body and the jacket, so as to flow only along the spiral groove from the inlet thereto, to the outlet thereof.

Other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a schematic diagram of an ice making apparatus of the prior art. [0010]
FIG. 2 is an elevational view, partially broken away and shown in longitudinal section, of the auger-type ice generating apparatus embodied on the system shown in FIG. 1. [0011]
FIG. 3 is a perspective view of the evaporator body and jacket of this invention, shown assembled at the left of FIG. 1, and shown longitudinally exploded at the right of FIG. 1.[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to the drawings, wherein like reference numerals indicate like elements throughout the several views, there is shown in FIGS. 1 and 2 an ice making apparatus in accordance with one preferred embodiment of the prior art, of which the present invention is an improvement. The illustrated apparatus is shown generally as comprising an auger-type [0013] ice generating apparatus 10, with a motor means 26 to drive the ice generating apparatus 10, an input line for water 18 from a water source 16 to be frozen, an outlet delivery line 12 for delivery of chunks of ice to an ice retaining means 14, a refrigeration means comprising a compressor means 20, a condenser means 22, an expansion valve 27, and evaporator 24 to supply refrigeration to the ice generating means 10.
In operation of the ice maker according to the prior art, conventional refrigerant under pressure is sent from the compressor means [0014] 20 via line 37 to the condenser means 22. The refrigerant is thereafter liquefied within the condenser means 22 and then passed through an expansion valve 27 to the evaporator 24. Evaporator 24, which completely surrounds the ice making machine 10, boils the liquid refrigerant under low pressure to extract heat from, and accordingly cool, the generally cylindrical ice freezing chamber. Evaporator 24 additionally comprises an evaporator cover 29 which serves as an insulator and protective cover. Water is supplied to the cylindrical freezing chamber 30, which houses an ice auger 28, from a water source 16 through water input line 18. A constant level of water 25 is maintained in the freezing chamber. Water freezes on the inner wall 38 of the freezing chamber 30 and is scraped off by means of the ice auger 28.
The [0015] ice generating apparatus 10 according to the prior art is shown in greater detail in FIG. 2. The auger 28 is disposed vertically in the interior of the freezing chamber 30 and is driven by shaft 44. Actuation of the motor means 26 results in a rotation of the auger 28 which causes ice to be scraped off the inner wall 38 of the freezing chamber 30 in flaked form. The ice generating apparatus 10 includes a water inlet 32, formed on its lower end for receiving water from the inlet line 18, and an ice discharge 34, formed on the upper end for delivering generated ice to the delivery line 12. Tubing 36 is also included, wrapped a plurality of times around the freeing chamber 30 which defines the aforementioned evaporator 24. Evaporator 24 includes an inlet 33 for receiving the refrigerant from the expansion valve 27, and refrigerant vapor is passed out through an outlet 35, into outlet line 54 where, as shown in FIG. 1, it is carried back to the compressor means 20. The refrigerant extracts heat from the ice generating apparatus 10 through the walls of freezing chamber 30 as it is passed through the evaporator 24. This causes some of the water contained within the freezing chamber 30 to freeze along the inner wall 38.
Auger [0016] 28 includes at least one coiled band of scrapers 42 extending outward from the auger surface 56, in close proximity to the inner wall 38 of the freezing chamber 30. A drive shaft 44 connects to the motor means 26 extending axially through the auger 28. Accordingly, as auger 28 is rotated, the scraper 42 shaves the ice formed on the inside walls 38, carrying it axially upward, in the form of slush, to be compacted against an annular compacting head 51.
As indicated above, the ice discharged through the [0017] discharge 34 is sent via line 12 to the retaining means 14.
The use of a prior art evaporator that includes a wrapping of copper tubing around a cylindrical body is avoided. In accordance with the prior art, such a copper tube, when brazed into a refrigeration circuit, embodies the refrigerant flow canal of the evaporator. Attachment of the wrapped tube to the cylinder body is typically accomplished by using a solder to bond them together. Often the wrapped assembly is dipped into a molten solder tank, allowing the solder to flow underneath and in between the copper tubing wrap. Such attachment and subsequent insulation of the copper tubing wrap is a labor and process intensive endeavor. Additionally, evaporator performance and reliability depend on proper execution of the process because proper copper tube attachment is critical to ensure heat transfer from the water within the evaporator to the refrigerant in order to freeze the water, and it is vital that moisture be sealed out of the wrapped tubing area of the evaporator assembly. If moisture is not sealed out and ice is formed between the copper tubing wrap and body, the subsequent expansion and contraction due to freeze/thaw operation cycles may cause copper wrap separation and/or structural failure of the body itself. Generally the solder is used not only to bond the copper tube to the body, but also acts as a moisture seal. [0018]
The problems associated with a wrapped and dipped evaporator manufacturing process are numerous. For example, the wrapped tube may tend to distort as it is wrapped around the body, creating voids and air gaps that can harm performance. Furthermore, the wrap may tend to “spring” when the assembly is removed from the wrapping apparatus, so the ends of the copper tube must be attached, typically via spot welding, to the body, in order to counter such tendency to “spring”. If the wrap is too tight, the solder will not flow properly. If the wrap is too loose, the heat transfer may not be appropriate. Furthermore, solder adhesion is problematic, especially when the body is stainless steel. At a minimum the body needs to be fluxed in an acid prior to dipping it into a solder, if not actually pre-tinned prior to wrapping. It has been found that solder adhesion is critical to evaporator performance. Additionally, in a wrap assembly, the assembly must be pre-heated prior to solder dipping, in order to avoid dangerous eruption of the solder tank which could occur should a cold assembly be introduced into molten solder. Furthermore, solder must never flow to the interior of the evaporator body, because of the lead content of the solder, but sealing of the ends of the evaporator during the dipping process has been found to problematic. Additionally, attaching insulation to the exterior of the dipped assembly is difficult due to the uneven outer surface. Typically, a shell is placed around the assembly, and a foam-in-place operation is performed, with the intent of having the insulation flow into the voids, further sealing the dipped area from moisture. [0019]
Referring now to FIG. 3, it will be seen that the [0020] improved evaporator 125 of the present invention is generally designated in place of the evaporator 24 of FIGS. 1 and 2, and comprises an evaporator body 130 and a jacket 131.
The [0021] evaporator body 130 has an inner cylindrical wall 138 and, on its outer cylindrical surface, a spiral groove 140, which is milled, or otherwise cut into the exterior cylindrical surface of the evaporator body 130 to define a spiral groove 140 from a location above the lower end 141 of the body 130, to a location below the upper end 142 thereof. At opposite ends of the spiral groove 140 there are circumferential grooves 143, 144.
A [0022] refrigerant inlet port 145 is provided in the cylindrical jacket 125, fed by the refrigerant delivery line 39 of FIG. 1, with the refrigerant being carried off via refrigerant discharge port 146, to the refrigerant outlet line 54 of FIG. 1.
It will be apparent that, except for the evaporator construction, the ice making apparatus of this invention is in accordance with the apparatus of FIGS. 1 and 2, with the evaporator of FIGS. 1 and 2 being replaced by the evaporator construction of FIG. 3. [0023]
The cylindrical jacket [0024] 131 has an interference fit against the outer peripheral edges 147 of the spiral cut 140, to seal refrigerant that enters via port 145, to remain within the spiral groove 140, from its inlet location 145, to its discharge location 146.
The manner in which the interference fit is achieved is by heating the jacket [0025] 131 prior to sliding it into place over the body 130 of the evaporator 125, whereby the jacket 125 thermally expands to a greater diameter, or outwardly, in the radial direction. After the jacket 125 is in place over the body 130, it is cooled and shrinks or reduces in diameter, or in a radial direction, until the inner cylindrical surface 148 thereof tightly engages against the outer peripheral edges 147 of the continuous helical or spiral groove 140 formed on the outer surface of the body, whereby it tightly seals thereagainst.
Thus, refrigerant entering via [0026] inlet port 145, into circumferential groove 143, is caused to pass along the helical groove until it reaches the upper circumferential groove 144, whereby it can exit the evaporator via exit port 146, to line 54, and back to the compressor 20.
An [0027] auger 28 disposed inside the auger body thus, as set forth in the description above with respect to FIGS. 1 and 2, scrapes ice from the inner cylindrical wall 138 of the body, delivering the same upward through the evaporator, to discharge via ice discharge port 134, to an ice delivery line 12, back to an ice retaining means 14.
The jacket [0028] 131 is welded to the evaporator body 130 at upper and lower ends thereof, at locations 150 and 151, as shown in FIG. 3, to ensure proper refrigerant sealing within the groove 140.
It will be seen that, in accordance with this invention, the manufacturing process for forming an evaporator is greatly simplified, in that it is not necessary to use a wrapped tube construction, and the problems associated with a wrapped tube construction are thereby avoided. Moreover, the spiral groove that is formed in accordance with this invention is no longer subjected to variations that are inherent in a wrapped dipped tube construction. Additionally, with the present invention moisture can no longer affect the integrity of the refrigerant path or evaporator structure. Additionally, in accordance with the present invention, more simplified forms of insulation can be used, for example, a simple foam material can be fastened in place to insulate the evaporator. Additionally, by employing circumferential grooves at each end of the body, the heat transfer between thick-walled ends of the evaporator and the spiral groove is minimized. Furthermore, by locating the refrigerant inlet and [0029] outlet ports 145 and 146 as disclosed herein relative to the spiral groove 140, refrigerant turbulence can be effected to the highest degree, with minimal loss due to pressure drop.
It will be recognized by those skilled in the art that changes may be made in the above described embodiments of the invention without departing from the broad inventive concepts thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications which are within the scope and spirit of the invention as defined by the appended claims. [0030]

Claims

What is claimed is:

1. An ice making apparatus comprising:

(a) a generally cylindrical and hollow freezing chamber;

(b) a compacting head at an end of said freezing chamber;

(c) a rotatable ice auger sized to fit into said freezing chamber whereby said auger scrapes ice formed on the walls of said chamber and conveys the ice toward a discharge end of said auger and said compacting head;

(d) an evaporator comprising an evaporator body and a jacket;

(e) the evaporator body having a continuous generally spiral grove on its outer cylindrical surface, terminating in a radial outward edge; with the evaporator having a refrigerant inlet and refrigerant outlet.

(f) the evaporator jacket being telescopically disposed over the spiral groove of the evaporator body and being in interference fit against the outward edge of the spiral groove, sealingly engaging the evaporator jacket against the evaporator body, whereby refrigerant entering into the groove is sealingly trapped therein between a refrigerant inlet and a refrigerant outlet.

2. The apparatus of claim 1, wherein the evaporator body includes a cylindrical groove at a lower end thereof and another cylindrical groove at an upper end thereof, with the cylindrical groove being in respective communication with the refrigerant inlet and refrigerant outlet.

3. The apparatus of claim 1 wherein the jacket is welded to the evaporator body at both upper and lower ends of the evaporator body.

4. The apparatus of claim 1, wherein the spiral groove comprises a helical groove.

5. The apparatus of claim 1, wherein the interference fit is obtained by a thermally expanded jacket that is subsequently cooled to effect the interference fit against the outward edge of the spiral groove.

6. The apparatus of claim 1, wherein the compacting head is annular and is disposed normal to the axis of the freezing chamber.

7. A method of making an ice making apparatus comprising:

(a) providing a generally cylindrical and hollow freezing chamber;

(b) providing a compacting head at an end of said freezing chamber;

(c) providing a rotatable ice auger sized to fit into said freezing chamber and disposing the auger in the freezing chamber whereby said auger scrapes ice formed on the walls of said chamber and conveys the ice toward a discharge end of said auger and said compacting head;

(d) providing an evaporator comprising an evaporator body and a jacket;

(e) providing on the evaporator body a continuous generally spiral grove on its outer cylindrical surface, terminating in a radial outward edge;

and providing to the evaporator with a refrigerant inlet and refrigerant outlet.

(f) telescopically disposing the evaporator jacket over the spiral groove of the evaporator body to be in interference fit against the outward edge of the spiral groove and thereby sealingly engaging the evaporator jacket against the evaporator body, whereby refrigerant entering into the groove is sealingly trapped therein between the refrigerant inlet and the refrigerant outlet.

8. The method of claim 7, including providing the evaporator body with a cylindrical groove at a lower end thereof and another cylindrical groove at an upper end thereof, so that the cylindrical groove is in respective communication with the refrigerant inlet and refrigerant outlet.

9. The method of claim 7, including the step of molding the jacket is welded to the evaporator body at both upper and lower ends of the evaporator body.

10. The method of claim 7, wherein the step of providing the spiral groove comprises forming a helical groove.

11. The method of claim 7, wherein the interference fit is obtained by thermally expanding the jacket and subsequently cooling the jacket to effect the interference fit against the outward edge of the spiral groove.

12. The method of claim 6, wherein the step of providing a compacting head comprises the step of providing an annular compacting head, normal to the axis of the freezing chamber.