Ice-machine evaporator and control system

Abstract

An apparatus and method for forming ice inside a helical refrigerated tube and harvesting the ice by warming the tube is provided. The device uses water pressure to push the ice out of the evaporator. At least a portion of the body of the evaporator is formed by extrusion. The evaporator can be made from aluminum.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to United States Provisional Patent Application No. 60/874,625, filed on Dec. 13, 2006.

FIELD OF THE DISCLOSURE

This invention relates to ice-making machines. More particularly, this invention is related to an evaporator for an ice-making machine and a control system for an ice-making machine.

BACKGROUND OF THE DISCLOSURE

Contemporary ice-making machines have an evaporator device with an array of ice cells arranged in a grid of horizontal rows and vertical columns, a portion of which is shown in FIG. 1. While these machines do a good job of manufacturing ice at a reasonable level of energy efficiency, reducing the cost of such machines is always desirable for the manufacturer. Likewise, these machines tend to be fairly complex, involving many parts, electronics and the like. This level of complexity contributes to lower reliability than would be possible if the machines were more simple in nature.

Thus, there is a need for an ice making system that reduces both the cost and complexity of the ice making system, and thereby also increases it's reliability.

SUMMARY OF THE DISCLOSURE

The present disclosure provides an evaporator for an ice-making machine. The evaporator comprises a body made at least in part by an extrusion process, wherein the body has a refrigerant channel and a water channel with an inner surface. The said refrigerant channel is adapted for flow of refrigerant therethrough, the inner surface being adapted for formation of ice thereon, and the refrigerant channel is in thermal communication with said water channel.

The present disclosure also provides an ice-making machine that comprises an evaporator and a control system comprising a single switch that senses water level in a reservoir located at an outlet of the evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional plan view of a portion of a prior art evaporator device;

FIG. 2 is a perspective view of the evaporator device of the present invention; and

FIG. 3 is a schematic diagram of a control system that is used with the evaporator device of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to FIG. 2, a helical evaporator is shown and generally referred to by reference numeral 100. Water is circulated through the helical tube or channel 150 via inlet 155 and outlet 160. Ice forms on the inside of the tube 150. The ice is initially formed along the walls of the tube 150, then grows inward toward the center of the tube. Once the ice has frozen solid at some point within the length of tube 150, which stops the flow of water, the tube 150 is heated to release the ice. The force of the water being pumped through the tube 150 forces the ice out of the tube. The ice is broken into cubes as it leaves the tube 150. Preferably, the ice breaks into hollow, cylindrical ice cubes as it is being ejected, and can be ejected into a bin (not shown).

In the present invention, the evaporator 100 is an extruded aluminum tube 150 comprised of an aluminum alloy, such as, for example, one of the corrosion-resistant alloys made by Brazeway Corporation, Adrian, Mich. The tube 150 is extruded to provide a large center passageway for the water/ice, with adjacent passageways, tubes or channels 175 for refrigerant. Refrigerant may be routed through these adjacent passageways 175 in a path that provides more refrigeration near the water inlet 155 of the evaporator. This insures that the ice forms a solid “plug” in that area first.

This plug is utilized to push the ice out of the evaporator 100 during a harvest portion of an ice-making cycle, discussed in further detail below. While the exemplary embodiment of the evaporator 100 has a pair of refrigerant channels 175 on opposing sides of the water channel 150, the present disclosure contemplates alternative numbers of refrigerant channels, as well as alternative shapes and paths.

Evaporator 100 can be used in an ice-making machine that includes several other components known to those in the art. For example, evaporator 100 can be used in conjunction with a refrigerant circuit that includes a compressor, condenser, and an expansion device (not shown), which supplies cold refrigerant to refrigerant channels 175. Evaporator 100 can also be used in conjunction with a source of water (not shown) that supplies water to water inlet 155, that is frozen in the manner discussed above.

Prior art helical or tubular ice making evaporators are of a tube-in-tube design (water flowing through the center of the inner tube, with refrigerant flowing through the annular space between the two tubes). In these prior art evaporators, the water tube was constructed from copper, which is not allowed by the National Sanitation Foundation (NSF) for ice making. The aluminum alloy used in the present disclosure is NSF approved, making evaporator 100 viable for use in commercial ice machines in the United States. It is difficult or impossible to coat the copper on the inside of the tube-in-tube evaporators of the prior art.

Thus, compared to evaporators of the prior art, the present disclosure has provided an evaporator design that is significantly less expensive. This is due to the low cost of the extruded aluminum compared to a soldered copper assembly. Copper evaporators also require expensive nickel plating for NSF approvability, which can add significantly to the cost of the evaporator, if it is even possible to achieve. The present invention evaporator requires no such plating. Eliminating the nickel plating also improves reliability, since failure of that plating is a common failure mode for ice machines.

Evaporator 100 can be used in conjunction with a control system that can control the ice-making cycle. Referring to FIG. 3, the ice making cycle is controlled by a single level switch 50 that senses the water level in a reservoir (not shown) located at the outlet 160 of evaporator 100. Level switch 50 can be, for example, a pressure sensing or a float switch. The reservoir is provided with holes so that it constantly drains. During the freezing cycle, water flows constantly into this reservoir at a rate that exceeds a “leak rate” of the water out of the reservoir. This causes the reservoir to constantly overflow, and the level of water in the reservoir to always be at the top of the reservoir.

As the ice grows inside the evaporator 100, the water flow rate decreases and eventually stops. When the water flow rate has slowed greatly (or stopped), the “leak rate” of the reservoir exceeds the incoming water flow rate, and the water level in the reservoir drops. When the reservoir water level reaches a predetermined minimum point, the water level sensing switch 50 opens a hot gas valve 52 in the refrigeration system, which commences a harvest cycle. This causes warm refrigerant to enter refrigerant channels 175, and loosen the ice. The ice will automatically eject due to the pressure of the water being pumped into the evaporator 100.

Once the ice has been ejected from the evaporator 100, water will again begin to flow through the evaporator, and will fill the reservoir. Once the reservoir has filled above the reset point of the switch, the switch will open, causing the hot gas valve to close, and the next freezing cycle to begin. The single switch design eliminates the need for timers, relays, probes, boards, purge valve, curtains or curtain switches which greatly reduces the cost and increases the reliability of the ice-making machine.

The other components included in FIG. 3 are well known to those skilled in the art, and provide control of the compressor, the water pump, the air condenser fan, the water purge valve, and manual cleaning activities. The circuit diagram of FIG. 3 also shows the bin fill switch (used to turn off the machine with the ice holding bin (not shown) has filled, the high-pressure safety switch (used to turn off the machine in the event of excessive pressure) and the high-temperature safety switch (used to turn the machine off in the event of excessive temperature at the evaporator 100.

The control system for this machine is extremely simple and inexpensive. For example, the controls illustrated in FIG. 3 cost in the neighborhood of $20. This compares to typical ice machine control systems, which cost anywhere from $40 for a simple electromechanical control to $80 for an electronic control system. Reducing the control system to a single switch also greatly improves reliability, when compared to more complicated control systems typically employed in conventional commercial ice machines.

The performance of any ice machine is largely a function of the freezing surface area of the evaporator. The greater the surface area, the better the performance (ice making capacity and energy efficiency). Because evaporator 100 is an extremely cost effective evaporator—in terms of freezing surface area per dollar—it becomes cost-effective to put an evaporator with a larger amount of ice-making surface area in a machine, making that machine's performance very good. The length of the helical evaporator 100 is easily adjustable allowing for fine-tuning for each compressor.

Advantageously, the present disclosure has found that evaporator 100 “scours” itself each cycle to provide for sanitation. Additionally, the evaporator surface is completely smooth, without the cracks or crevices found in a conventional evaporator, thus reducing the need for cleaning. Due to the self-scouring design of evaporator 10, it does not need to be cleaned. Other parts that do need to be cleaned, such a sump used for catching the water exiting evaporator 100, or the reservoir referred to above, are easily accessed by a user. Only a few parts of the ice machine need to touch the water/ice: evaporator 100, the sump, a pump that supplies water to evaporator 100, and a water tube that supplies water to evaporator 100. This minimizes the need for NSF approved materials.

The ice machine of the present disclosure utilizes a greatly simplified control system, as compared to traditional machines. Thus, the ice machine of the present disclosure provides for dramatically simplified wiring, fewer parts that have the potential to fail, since troublesome ones have been eliminated, and ease of diagnosis and repair.

The present disclosure also contemplates alternative evaporator designs that utilize some or all of the features of the above-described evaporator 100.

While the instant disclosure has been described with reference to one or more exemplary or preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope as described herein.

Claims

1. An evaporator for an ice-making machine comprising:

a body made at least in part by an extrusion process, wherein said body has a refrigerant channel and a water channel with an inner surface, said refrigerant channel being adapted for flow of refrigerant therethrough, said inner surface being adapted for formation of ice thereon, and wherein said refrigerant channel is in thermal communication with said water channel.

2. The evaporator of claim 1, wherein said body has a helical shape.

3. The evaporator of claim 1, wherein said refrigerant channel is a plurality of refrigerant channels.

4. The evaporator of claim 1, wherein at least two of said plurality of refrigerant channels are diametrically opposed along an outer surface of said water channel.

5. The evaporator of claim 1, wherein said body is made from aluminum.

6. An ice-making machine comprising:

an evaporator; and

a control system comprising a single switch that senses water level in a reservoir located at an outlet of the evaporator.

7. The machine of claim 6, wherein the reservoir has holes therethrough for drainage.

8. The machine of claim 6, wherein during a freezing cycle, water flows into the reservoir at a rate that exceeds a drainage rate of the reservoir.

9. The machine of claim 8, wherein when a water level of the reservoir reaches a predetermined minimum, the single switch opens a hot gas valve in the circuit to commence a harvest cycle and eject ice at least in part based on a pressure of the water being pumped into the evaporator.