Patent Description:
Ice making machines, or ice makers, typically comprise a refrigeration and ice making system that employs a source of refrigerant flowing serially through a compressor, a heat rejecting heat exchanger (e.g., a condenser), a refrigerant expansion device, and an evaporator assembly including a freeze plate comprising a lattice-type cube mold. Additionally, typical ice makers employ gravity water flow and ice harvest systems that are well known and in extensive use. Ice makers having such a refrigeration and ice making system are often disposed on top of ice storage bins, where ice that has been harvested is stored until it is needed. Such ice makers may also be of the "self-contained" type wherein the ice maker and ice storage bin are contained in a single unit. Such ice makers have received wide acceptance and are particularly desirable for commercial installations such as restaurants, bars, hotels and various beverage retailers having a high and continuous demand for fresh ice.

In these ice makers, water is supplied at the top of an evaporator assembly which directs the water in a tortuous path toward a water pump. A portion of the supplied water collects on the freeze plate, freezes into ice and is identified as sufficiently frozen by suitable means whereupon the freeze plate is defrosted such that the ice is slightly melted and discharged therefrom into an ice storage bin. Typically, these ice machines can be classified according to the type of ice they make. One such type is a grid style ice maker which makes generally square ice cubes that form within individual grids of the freeze plate which then form into a continuous sheet of ice cubes as the thickness of the ice increases beyond that of the freeze plate. After harvesting, the sheet of ice cubes will break into individual cubes as they fall into the ice storage bin. Another type of ice maker is an individual ice cube maker which makes generally square ice cubes that form within individual grids of the freeze plate which do not form into a continuous sheet of ice cubes. Therefore, upon harvest individual ice cubes fall from the freeze plate and into the ice storage bin. Control means are provided to control the operation of the ice maker to ensure a constant supply of ice. Various embodiments of the invention can be adapted to either type of ice maker, and to others not identified, without departing from the scope of the invention.

Typical ice makers have extraneous heat transfer on the back surfaces of the evaporator assembly in which energy or heat is removed from the air inside the ice maker rather than from the water to be frozen into ice. This extraneous heat transfer represents inefficiency in typical ice makers. Additionally, evaporator assemblies in typical ice makers will condense and freeze moisture in the air inside the ice maker and/or will create frost on the back of the evaporator assembly where there is exposed copper. This presents another route for extraneous heat transfer as energy is transferred to condense and freeze airborne water or to create frost rather than cooling the water to be frozen into ice. Then, when warm refrigerant is directed through the serpentine tube of typical evaporators to harvest ice from the evaporator, a portion of the energy that is intended for melting the ice will instead be absorbed by the frost on the back side of the evaporator. Again, this extraneous heat transfer reduces the efficiency of typical ice makers.

Certain ice makers, particularly those of the flaked, pellet, and nugget continuous-extrude type ice makers may include foam insulation surrounding the refrigerant tubing. However, one cannot simply use blown insulation by itself, because polyurethane is only <NUM>% closed cell. The remaining <NUM>% may fill with moisture overtime and ultimately break down the entire foam. The soggy foam (now frozen) would potentially render the ice maker un-harvestable, leading to catastrophic failure.

Another issue with typical ice makers is that any water that contacts and/or resides on the back side of the evaporator (e.g., from water leaks, condensation, and/or frost formation) creates a potential for damage to the evaporator from the expansion and contraction associated with the freezing and thawing of such water. The presence of this moisture also increases the possibility for corrosion of the evaporator.

Furthermore, the air inside a typical ice maker can be contaminated with airborne contaminants from the ambient environment (e.g., restaurant, hospital, bar, etc.). In typical ice makers, the back side of the evaporator is exposed to these contaminants and the backside of the evaporator typically does not get cleaned due to a lack of access and a lack of instruction on how to clean the back side of the evaporator. Accordingly, there can be a buildup of biological contaminants on the back side of typical evaporators. When the backside of the evaporator then condenses moisture and drips into the ice maker, the sump below the evaporator, and/or the ice storage bin below the ice maker, that dripping condensation may contain biological contaminants and thus may contaminate the ice making water and/or the produced ice. As a result of this and because the back side of the evaporator is considered in the food zone of typical ice makers, the back side of the evaporator should be cleaned periodically. This cleaning step can be a difficult, expensive, and/or undesirable step. Consequently, the cleaning of the back side of the evaporators of typical ice makers is rarely, if ever, done.

<CIT> discloses a method and apparatus for making ice wherein an ice cube maker has a generally upright gridded evaporator, a hot gas defrost for harvest of cubes, a storage bin below the evaporator, a hinged cube and water curtain between the evaporator and the bin, a new and improved control for the freeze cycle, and a new and improved control for the harvest cycle. The freeze cycle control has a temperature sensor, on a backside of the evaporator, circuitry to count down a predetermined time after a predetermined plate temperature has been sensed, the circuit terminates the countdown if the plate temperature exceeds the predetermined temperature and restarts the countdown when the predetermined temperature is again reached, and the circuit switches the refrigeration from freeze to hot gas defrost when the countdown is completed for harvest of the ice cubes; the harvest control has an ice curtain sensor connected to the refrigeration control, and a lever between the ice curtain and the sensor, when the curtain is opened by ice cubes the sensor picks up the lever movement and the control switches the refrigeration from the defrost to the freeze cycle.

<CIT> addresses the problem of easily and firmly adhering upper and lower cases together without deteriorating the performance of an electronic part housed therein. To that end, said patent discloses an upper and lower case for battery pack combined so as to mutually butt connecting surfaces formed substantially on the whole circumference thereof. A projection and receiving part for welding are provided on the angle parts of the connecting surfaces. The upper case is put on the lower case containing a secondary battery, the part of the projection is ultrasonically welded to temporarily fix the upper and lower cases, and allowed to stand until the adhesive preliminarily applied to the connecting surfaces entirely is hardened. Since substantially the whole circumference of the upper and lower cases is adhered by the adhesive, the adhesive strength is increased. Further, since they are temporarily fixed in the state where the connecting surfaces are closely fitted to each other by ultrasonic welding, the upper and lower cases can be allowed to stand as they are without using a special fixing tool.

<CIT> discloses a single molded piece of plastic as an evaporator frame. A low durometer gasket material is molded in place on the single molded piece of plastic. The gasket aids in sealing the evaporator frame and the evaporator pan.

The present invention provides an evaporator assembly for an ice maker according to claim <NUM> and a method of making an evaporator assembly for an ice maker according to claim <NUM>.

These and other features, aspects and advantages of the invention will become more fully apparent from the following detailed description, appended claims, and accompanying drawings, wherein the drawings illustrate features in accordance with exemplary embodiments of the invention, and wherein:.

Like reference numerals indicate corresponding parts throughout the several views of the drawings.

As described herein, embodiments of the invention are directed to an evaporator assembly wherein the back side of the evaporator is covered, insulated, exempt from NSF regulations, and protected from heat loss and the damaging effect of the water and corrosion. Because the back side of the evaporator is covered, it does not need to be plated (with electroless nickel, for example), saving considerable cost and it cannot contaminate the ice making water.

With reference to <FIG>, an embodiment of evaporator assembly <NUM> is described. Evaporator assembly <NUM> includes evaporator <NUM> and an evaporator housing formed by housing top <NUM>, bottom <NUM>, sides <NUM> and <NUM>, and back <NUM>. Preferably, the top <NUM>, bottom <NUM>, sides <NUM> and <NUM>, and back <NUM> of the evaporator housing are plastic. The top <NUM>, bottom <NUM>, sides <NUM> and <NUM>, and back <NUM> of the evaporator housing may have features allowing them to be assembled together in a variety of ways, including snap-fit features, bolts and nuts, etc. The inner surfaces of the top <NUM>, bottom <NUM>, sides <NUM> and <NUM> may include a gasket material to aid in sealing the evaporator housing water tight. Evaporator <NUM> includes an evaporator pan <NUM> having a back wall <NUM> and a left sidewall <NUM>, a right sidewall <NUM>, a top sidewall <NUM>, and a bottom sidewall <NUM> extending from back wall <NUM> toward the front side of evaporator <NUM>. Left, right, and top sidewalls <NUM>, <NUM>, <NUM>, are substantially perpendicular to back wall <NUM> while bottom sidewall <NUM> preferably angles slightly downward. The evaporator pan <NUM> includes a series of studs <NUM> that may be used to mount evaporator assembly <NUM> to an internal structure of the ice maker (not shown). The evaporator housing may have corresponding mating openings <NUM>, through which the studs <NUM> may pass.

A population of vertical and horizontal strips <NUM>, <NUM> are secured in evaporator pan <NUM> to form a lattice of ice cube "molds. " Evaporator pan <NUM> with vertical and horizontal strips <NUM>, <NUM> may also be called a freeze plate. Attached to the back side of back wall <NUM> of evaporator pan <NUM> is a serpentine tube <NUM> through which cold refrigerant flows to lower the temperature of evaporator <NUM> so that ice can be formed therein. Serpentine tube <NUM> includes inlet tube <NUM> and outlet tube <NUM> which extend through evaporator assembly <NUM>, as described more fully elsewhere herein. Locating the inlet tube <NUM> at the bottom of the evaporator assembly <NUM> assists in ensuring an even distribution of temperature across the evaporator. The serpentine tube <NUM> may be attached to the back side of back wall <NUM> of the evaporator pan <NUM> in a number of conventional ways, including using a soldering or brazing process.

The components of evaporator <NUM> are preferably formed of copper. To satisfy the water contact cleanliness requirements of NSF for commercial ice machines, all areas of evaporator <NUM> that are considered to be in the "food zone" of the ice maker cannot be bare copper and thus must be plated. Any portion of evaporator <NUM> that could potentially drip water into the food zone is considered to be inside the food zone and must comply with this requirement. Because of this requirement, typical ice machine evaporators must be completely plated such that no un-plated, bare copper surfaces are exposed. Typical evaporators are exposed on all sides, thus the entire surface of typical evaporators - front and back - must be plated. This plating, typically a thin layer of electroless nickel (EN), is quite expensive, costing roughly as much as the rest of the evaporator. As described more fully elsewhere herein, because the back side of evaporator <NUM> is covered by evaporator housing, the back side of evaporator <NUM> does not need to be plated. Thus only the front side of back wall <NUM>, sidewalls <NUM>, <NUM>, <NUM>, and <NUM> of evaporator pan <NUM> are plated. The back side of back wall <NUM> and serpentine tubing <NUM> are not required to be plated.

Referring now to <FIG>, two passageways <NUM>, <NUM> extend through back wall <NUM> of evaporator housing. Passageways <NUM>, <NUM> permit inlet and outlet tubes <NUM>, <NUM>, respectively, of serpentine tube <NUM> to pass through back wall <NUM> of the evaporator housing such that serpentine tube <NUM> can be coupled with the remaining components of the refrigeration system of an ice maker (not shown). Passageways <NUM>, <NUM> are preferably circular in shape; however, passageways may be rectangular, square, ovular, etc. without departing from the scope of the invention. Rubber grommets (not shown) may be inserted into passageways <NUM>, <NUM> to seal any gap between passageways <NUM>, <NUM> and inlet and outlet tubes <NUM>, <NUM>, respectively, of serpentine tube <NUM>. In certain embodiments, a caulk or sealant may be used in addition to or in place of grommets to seal any gap between passageways <NUM>, <NUM> and inlet and outlet tubes <NUM>, <NUM>.

A third passageway <NUM> may be provided in the back wall <NUM> in order to inject insulating material into the interior of the evaporator housing assembly <NUM> as described below.

As illustrated in <FIG>, the evaporator assembly <NUM> further includes an insulating material <NUM> layered over at least a majority of the length of the serpentine tube <NUM>. The insulating material <NUM> minimizes the amount of heat dissipated by the serpentine tube <NUM> and provides a water-tight seal. Preferably, the insulating material <NUM> is a heavy-bodied, water-based, vinyl acrylic, general-purpose mastic that is typically used in both interior and exterior insulation systems. Examples of insulating material <NUM> include two-part silicone materials such as QSil <NUM> from Quantum Silicones LLC of Richmond, VA.

Preferably, the insulating material <NUM> is applied in liquid form onto the serpentine tubing <NUM> to a thickness of approximately about <NUM> to about <NUM>. The insulating material <NUM> then cures, forming an integral layer of insulation that is impervious to water. In addition, the integral layer of insulation has no joints through which water can leak, will not rust, and adds rigidity and strength. As the insulating material <NUM> is poured in a liquid form, it cures into a mold that matches the geometry of the serpentine tubing <NUM> and can fill in all gaps within the back side of the evaporator pan.

After attaching the serpentine tube <NUM> to the evaporator pan <NUM>, and adding the insulating material <NUM> surrounding the serpentine tube <NUM>, the evaporator assembly <NUM> may be assembled. Thus the five components of the evaporator housing, namely housing top <NUM>, bottom <NUM>, sides <NUM> and <NUM>, and back <NUM> may be assembled together surrounding the evaporator pan <NUM> in order to form the complete assembly <NUM>. Forming the assembly results in a cavity formed between the back side of evaporator <NUM> (holding the serpentine tube <NUM>) and the front side of back wall <NUM> of evaporator housing, and further enclosed by the housing top <NUM>, bottom <NUM> and sides <NUM> and <NUM>.

As illustrated in <FIG>, the back <NUM> includes one or more raised edges <NUM>, <NUM>, <NUM>, and <NUM>. As shown in <FIG> and <FIG>, the raised edges <NUM>, <NUM>, <NUM>, and <NUM> preferably surround the perimeter of the back <NUM>. The raised edges <NUM>, <NUM>, <NUM>, and <NUM> extend outwardly away from the inner surface of the back <NUM> (i.e., the surface facing the serpentine tube <NUM>). As shown in <FIG> and <FIG>, the raised edges <NUM>, <NUM>, <NUM>, and <NUM> initially rest within grooves <NUM>, <NUM>, <NUM>, and <NUM> formed in the top <NUM>, bottom <NUM>, and sides <NUM> and <NUM>.

The back <NUM> is then ultrasonically welded to the top <NUM>, bottom <NUM>, and sides <NUM> and <NUM> in order to seal the entire assembly together as shown in <FIG>. The raised edges <NUM>, <NUM>, <NUM>, and <NUM>, which may be a raised triangular bead of material molded onto the surface of the back <NUM>, concentrate the ultrasonic energy to rapidly initiate the softening and melting of the surface of the back <NUM> and grooves <NUM>, <NUM>, <NUM>, and <NUM> as is known to those skilled in the art of ultrasonic welding. During welding, the raised edges <NUM>, <NUM>, <NUM>, and <NUM> melt flat to seal the back <NUM> into the grooves <NUM>, <NUM>, <NUM>, and <NUM>.

In various embodiments, the cavity may be filled with foam after evaporator assembly <NUM> is assembled. The foam may be open- or closed-cell foam comprised, for example, of polystyrene or polyurethane, etc. Preferably, the foam is an expanding-type foam that can be sprayed into the cavity through passage <NUM>. The foam preferably conforms to the back side of evaporator <NUM> so that it covers all or substantially all of the back side of evaporator pan <NUM> and the insulated serpentine tube <NUM> and fills all or substantially all of cavity. The foam may be sprayed into cavity after evaporator <NUM> and evaporator housing are assembled together. Another acceptable form is a two-part liquid form sold under the brand name Ecomate, in which the two parts mix and cure in place. After cavity is filled with sufficient amount of foam, a plug (not shown) may be inserted into or over the passageway <NUM> and may be held and sealed in place by the foam inside cavity. Additionally or alternatively, the plug may be held in by any type of sealant and/or adhesive, including, but not limited to, silicone caulk.

Filling the cavity provides insulation to the back side of evaporator <NUM> thus reducing or eliminating extraneous heat transfer on the back side of evaporator <NUM> which is common with typical evaporators as described more fully elsewhere herein. Consequently, filing the cavity with foam reduces or eliminates the possibility for condensation or frost to form on the back side of evaporator <NUM>, reduces or eliminates the possibility of the back side of evaporator <NUM> corroding, and increases the efficiency of both forming and harvesting ice cubes from evaporator pan <NUM> because extraneous heat on the back side of evaporator <NUM> is essentially eliminated. Furthermore, the foam within the cavity is completely protected from any moisture condensing on the serpentine tubing <NUM> by the insulating material <NUM>. As an alternative to filling the cavity with foam, the insulating material <NUM> may be applied to a thicker layer. Alternatively, one may use a single layer of standard blown foam in place of the insulating material <NUM>, particularly if a closed cell blown foam (about <NUM>% closed) becomes commercially available.

The increase in insulation effectively allows one to reduce the size of the evaporator <NUM>, thus minimizing the size of the required compressor and condenser for the identical ice making capacity. In tests of the embodiment described here, an icemaker can achieve slightly larger amounts of produced ice using significantly less energy.

Claim 1:
An evaporator assembly (<NUM>) for an ice maker comprising:
an evaporator pan (<NUM>) comprising a back wall and left, right, top and bottom sidewalls extending from the back wall;
a freeze plate located within the evaporator pan;
a serpentine tubing (<NUM>) thermally coupled to the back wall of the evaporator pan opposite the left, right, top and bottom sidewalls;
a first layer of insulation (<NUM>) formed on the serpentine tubing;
an evaporator housing attached to the evaporator pan and covering the serpentine tubing and the first layer of insulation, the evaporator housing comprising:
housing left, right, top and bottom sidewalls (<NUM>, <NUM>, <NUM>, <NUM>), wherein each sidewall comprises a groove (<NUM>, <NUM>, <NUM>, <NUM>); and
a housing back wall (<NUM>) seated into the grooves of the sidewalls, the housing back wall comprising a raised edge (<NUM>, <NUM>, <NUM>, <NUM>) melted flat in an ultrasonic welding process to seal the housing back wall to the housing left, right, top and bottom sidewalls.