WO1995033165A1

WO1995033165A1 - Thermoelectric water chiller

Info

Publication number: WO1995033165A1
Application number: PCT/US1995/006774
Authority: WO
Inventors: S. Spence Davis; R. Clark Lucas; Michael J. Nagy; Anthony E. Yeargin; Gerald M. Zinnbauer
Original assignee: Springwell Dispensers, Inc.
Priority date: 1994-05-27
Filing date: 1995-05-26
Publication date: 1995-12-07
Also published as: MX9605898A; AU699943B2; US5501077A; CA2191215A1; CN1159853A; EP0760927A4; AU2692895A; EP0760927A1

Abstract

A thermoelectric water chiller system (10) for cooling fluids, and including a mixing valve which enables dispensing of chilled water, warmer fluid, or a mixture of chilled and warmer fluid. Components needing periodic cleaning are readily removable from the system. A fan-cooled thermoelectric module assembly is used to form an ice block which chills the water, and a variable-speed fan (140) is controlled by a temperature sensor (142) to slow the fan (140) speed when chilling to a desired temperature is achieved, and to maintain the ice block at an optimum size. The system (10) is constructed to include a cold probe for cooling the fluid, with the cold probe including a cover acting as a secondary cold sink.

Description

THERMOELECTRIC WATER CHILLER

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a system for chilling drinking water, the system being particularly suitable for use with bottled drinking water. Water cooling is preferably provided by a thermoelectric heat-transfer module which is quiet and trouble-free as compared to compressor-type coolers.

2. Related Art

With the growing concern over the quality of water from public systems, bottled water and water filters, and associated dispensers, have become more prevalent. Many have realized the desirability of cooling the water as it is dispensed. Various approaches have been utilized to cool the water. For example, a conventional refrigerant circuit with a compressor, evaporator and condenser has been employed. Water in a dispenser has also been cooled with a thermoelectric module. A probe, extending into the water in a tank has been employed to transfer heat from the water to the thermoelectric module. Typically, an ice block builds on the probe to cool the water in the tank.

Several problems exist with such a dispenser. For example, it is difficult to control the dimensions of the ice block. If the ice block extends to the spigot of the dispenser, the spigot will freeze up. Also, the fan can generate unwanted noise. Furthermore, components of such a system cannot be removed to facilitate cleaning. Finally, although some thermoelectric dispensers provide for dispensing both chilled and unchilled water, this is accomplished through two separate valves, which may not be ideal aesthetically and does not permit ready mixing.

SUMMARY OF THE INVENTION

The present invention addresses these problems associated with known water dispensers. The water chiller of this invention has a thermally insulated outer housing which supports a removable main tank with a lower chamber for holding chilled water, and a thermal barrier assembly fitted in the tank to define an upper chamber for holding warmer water. Water from the upper chamber is gradually fed to the lower chamber as water from that chamber is dispensed. A user-adjustable proportioning valve enables dispensed water to be drawn from both the water chambers in a proportion which provides a desired water temperature.

A thermoelectric cooling system has a thermoelectric module in contact with a cold sink and a finned hot sink from which heat is extracted by fan-driven room temperature air. The cold sink is in direct contact with a heat exchange surface of the lower chamber of the main tank. The operating rate of this cooling system is controlled by varying the fan speed and/or power to the thermoelectric module which in turn regulates the size of an ice block which forms in the lower chamber. In a first embodiment of the present invention, the heat exchange surface includes a metal plate formed at the bottom of the lower chamber, which is cooled by the cold sink and in turn cools the water.

In a second embodiment of the present invention, the cold sink includes an aluminum cylinder, a "cold probe", that extends from the thermoelectric module. The heat exchange surface includes a protrusion in the main tank that surrounds and is in direct contact with the cold probe. Thus the protrusion acts as a plastic cover for the cold probe.

The cold probe is generally cylindrical, but is flattened on one side that faces the drain or spigot. As a result, an air-space is defined between the cold probe and the plastic cover.

Therefore, the ice block that forms around the cold probe is not as thick facing the flattened face as compared to the rest of the plastic cover. As a result, even if the ice block becomes large, it does not block water from exiting the spigot.

The tank and thermal-barrier assembly are secured to the housing by latches or clips which can be released to enable removal, without use of tools, of the tank and barrier assembly for convenient periodic cleaning. The adjustable proportioning valve is also readily removable from the tank for cleaning.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and characteristics of the present invention along with the method of operation and assembly will be appreciated from study of the following detailed description and the appended claims and drawings, all of which form part of this application. In the drawings:

FIGURE 1 is a sectional elevation of a thermoelectric water-chiller system according to a first embodiment of the present invention; FIGURE 2 is a bottom view of the first embodiment;

FIGURE 3 is a sectional elevation on line 3-3 of FIGURE 2; FIGURE 4 is a sectional elevation on line

4-4 of FIGURE 2;

FIGURE 5 is a sectional elevation on line 5-5 of FIGURE 2;

FIGURE 6 is a top view of a main tank of the system;

FIGURE 7 is a plan view of a main tank bottom plate;

FIGURE 8 is a perspective view of a bottom cover and channel portion of a thermal-barrier assembly of the system;

FIGURE 9 is an enlarged sectional elevation of a proportioning valve assembly;

FIGURE 10 is a perspective view of an outer sleeve of the valve assembly; FIGURE 11 is a perspective view of an inner sleeve of the valve assembly;

FIGURE 12 is a pictorial view of a rotatable intermediate sleeve of the valve assembly;

FIGURE 13 is a sectional view on line 13-13 Of FIGURE 9;

FIGURE 14 is a view similar to FIGURE 13 showing the rotatable sleeve of the valve assembly in a different position;

FIGURE 15 is a schematic diagram of an alternative circuit for thermistor control of electrical energy delivered to a thermoelectric module,*

FIGURE 16 is a cross-sectional view of a second embodiment of the present invention; FIGURE 17 is an exploded view of the cold probe, thermoelectric module, and heat sink assembly of the second embodiment;

FIGURE 18 is a cross-sectional view of the assembly illustrated in FIGURE 17;

FIGURE 19 is an exploded view illustrating the tank assembly according to the second embodiment;

FIGURE 20 is a circuit diagram illustrating the control circuit for the second embodiment; and

FIGURES 21A-21D are views illustrating the latching mechanism of the second embodiment.

DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

A water-chiller system 10 is shown in

FIGURES 1-5, the system having a double-wall and generally cylindrical outer housing 11 with an upper shell 12, a lower shell 13, and a circular base panel 14. The upper and lower shells define an enclosed annular space 15 which is preferably filled with a thermal insulating material such as polyurethane or polystyrene foam plastic. The shells are joined together at an outer annular joint 18, and by two or more threaded fasteners 19 around the lower end of the upper shell. The system is supported on four feet 21 (FIGURE 5) which, along with base panel 14, are secured to the housing by threaded fasteners 22. The feet 21 serve two purposes on the dispenser. The feet separate the system from a surface upon which the system rests, and also can be used to connect the system to a dispenser stand. A generally cylindrical main tank 24 for holding chilled water has an inwardly tapered bottom portion 25 defining a central circular opening 26. The upper end of the tank has a radially outwardly extending annular lip 27 which seats on a resilient seal ring against an upper end 28 of upper shell 12 when the tank is fitted within the housing as shown in FIGURE 1. The seal ring prevents water or water vapor from entering the space between main tank 24 and housing 11. The bottom of the tank is closed by a thin stainless-steel circular plate 30 (FIGURE 7) which extends across opening 26, and is secured in place by screws 31 (FIGURE 5) . Alternately, a locking ring such as described in more detail with regard to the second embodiment below may be employed to secure plate 30 to the bottom of the tank. A thick resilient ring-shaped gasket 32 between the tank and plate provides a fluid-tight seal. A thermal barrier assembly 35 is fitted within the upper end of main tank 24 to form a lower chamber and an upper chamber. The thermal barrier assembly minimizes heat transfer between chilled water in the lower chamber and water in the upper chamber. The assembly has a generally cylindrical sidewall 36, and a bottom wall 37. An outwardly and downwardly extending annular lip 38 extends from the upper end of sidewall 36 to overhang and rest against the upper end of the main tank. A resilient seal may be provided between main tank 24 and thermal barrier assembly 35 at the top of the main tank.

An annular recess 39 is formed in the undersurface of bottom wall 37, and a circular bottom cover 40 (FIGURES 1 and 8) is secured (e.g., by sonic welding) at its upper edge in the recess. A space 41 defined between the bottom wall and bottom cover is filled with a circular disk 42 of a thermally insulating material such as polystyrene foam plastic.

As shown in FIGURE 1, a conventional five-gallon water bottle 44 is inverted and supported on annular lip 38 of the thermal-barrier assembly. Bottled water at room temperature thus fills the upper chamber of system 10 within sidewall 36 above bottom wall 37, and is admitted to a lower chamber of main tank 24 through sidewall openings 45. In an alternative form, sidewall 36 can be replaced with a series of struts (not shown) between which water can flow around the thermal barrier

(which can be enlarged in diameter) into the lower chamber. In either case, the desired effect is to maintain stratification of the warmer water and chilled water, and thereby to achieve more rapid chilling of water in the lower part of the main tank. Use of a plurality of relatively small flow passages from the upper chamber to the lower chamber provides low-velocity admission of warmer water to minimize swirling and mixing of water in the lower chamber as chilled water is being dispensed.

The main tank 24 and thermal-barrier assembly 35 are secured within housing 11 by at least one circumferentially spaced f stening-means, such as latch assembly 46. Latch assembly 46 includes an intermediate member 46a that is pivotally attached to upper shell 12 and an outer member 46b that is pivotally attached to the other end of intermediate member 46a. Outer member 46b has a lip that engages a shoulder of upper shell 12 to hold main tank 24 thermal barrier assembly 35 in place.

A particular feature of this invention is a proportioning valve assembly 73 (FIGURES 4 and 9- 16) which enables dispensing of chilled water from the lower chamber only, warmer water from the upper chamber only, or a selectable mixture of chilled and warmer water. The valve assembly extends through and is supported by a horizontally positioned cylindrical outer tube 74 which extends through openings 75 and 76 in upper and lower shells of the housing, and is clamped in place by an inner snap-in retaining ring 77 fitted against an O-ring seal 78. The valve assembly includes a cylindrical outer sleeve 80 (FIGURES 9-10) with an enlarged and outwardly tapered head 81 at its outer end. An annular recess 82 is formed in the tapered head, and extends circumferentially about 100°. A bore 83 extends axially through the sleeve, and the diameter of the bore is slightly decreased as it passes through an inner end wall 84. A pair of oppositely oriented keyway slots 85 spaced at 180° are formed in the end wall. A pair of oppositely oriented upper and lower rectangular ports 86 and 87 are spaced at 180°, and formed through the sidewall of the outer sleeve adjacent the end wall. Annular grooves 88 and 89 are provided on the sleeve outer surface to receive O-ring seals. A rotatable intermediate sleeve 91

(FIGURES 9 and 12) makes a slip fit within bore 83 of the outer sleeve, and has at its outer end a radially extending flange 92 which seats in a mating recess in head 81 of the outer sleeve. An O-ring seats intermediate sleeve 91 to outer sleeve 80. A rotation arm 93 extends radially from flange 92, and the arm seats in annular recess 82 such that arm movement (and hence rotation of the intermediate sleeve) is limited by the extent of the recess. The intermediate sleeve has an inner portion 94, and a 180° slot 95 is formed through the sidewall of this portion adjacent the inner end of the sleeve.

A fixed-position inner sleeve 98 (FIGURES 9 and 11) makes a slip fit within the intermediate sleeve, and has at its inner end an enlarged head 99 which seats against the inner end of outer sleeve 80. 0-rings seal the inner sleeve 98 to intermediate sleeve 91. A bore 99A extends through the inner sleeve to terminate at head 99. A pair of opposed 180°-spaced lugs or keys 100 extend axially from the inner side of the head, and are positioned to mate with keyway slots 101 (FIGURE 9) in the end wall of the outer sleeve. A pair of 180°-spaced opposed ports 103 extend through the sidewall of the inner sleeve into bore 99A adjacent head 99.

An outer end 104 of sleeve 98 is threaded to receive a conventional dispensing valve or spigot 105 (FIGURES 4 and 9) having at its inner end a flange 106 which is positioned immediately adjacent or against the outer end of tapered head 81 of outer sleeve 80. The outer sleeve and intermediate sleeve are thus clamped between flange 106 and enlarged head 99 at the inner end of inner sleeve 98, enabling valve assembly 73 to be inserted into or withdrawn from the housing as a unit. Flange 92 of intermediate sleeve 91 is dimensioned to make a slip fit against flange 106 of the spigot to permit rotation of the intermediate sleeve. The inner portion of the valve assembly extends through a circular opening 108 formed in the lower sidewall of tank 24 to position lower port 87 of outer sleeve 80 in communication with chilled water in the tank.

A vertical wall structure 110 (FIGURES 8 and 9) is integrally formed with and extends downwardly from one side of bottom cover 40 of thermal-barrier assembly 35. Wall structure 110 performs the dual functions of conveying warmer water from above the thermal-barrier assembly to valve assembly 73, and clamping the inner end of the valve assembly within the lower end of tank 24.

Wall structure 110 has a base 111, and a pair of radially outwardly extending and spaced-apart sidewalls 112 which define at their outer ends oppositely extending circumferential ribs 113. A pair of inwardly extending shoulders 114 are formed at a lower portion of sidewalls 112, and lower surfaces 115 of the shoulders are cylindrically curved to fit against the inner portion of outer sleeve 80. An O-ring seal 117 is fitted in groove 89 around the outer sleeve to seal the valve assembly to the tank. Sidewalls 112 also define inwardly extending ribs 118 dimensioned to make a snug slip fit within keyway slots 85 of the outer sleeve. As best seen in FIGURE 6, a pair of downwardly and inwardly extending spaced-apart tapered guide ribs 120 are integrally formed in the inner surface of tank 24. Ribs 113 of wall structure 110 of the thermal-barrier assembly make a snug slip fit within mating guide ribs 120 to clamp the channel sidewalls in sealed engagement against the inner sidewall of the tank. Wall structure 110 and the tank sidewall between guide ribs 120 thus form a passageway 121 permitting water from the upper chamber to flow by gravity through a port 122 (formed through bottom wall 37 as shown in FIGURES 4 and 9) to upper port 86 of the valve-assembly outer sleeve (FIGURES 13-14) .

A thermoelectric chilling assembly 124 (FIGURES 3-5) is positioned in a space 125 at the bottom of system 10 between base panel 14 and the lower end of outer housing 11. Assembly 124 has at its upper end a thick circular aluminum cold sink plate or disk 126 around the perimeter of which is insert-molded a plastic clamping ring 127 which engages a radially outwardly extending flange^'128 on the lower end of the disk. A hot sink aluminum block 130 is positioned below and slightly spaced from the undersurface of disk 126, and a thermoelectric module 131 (commercially available types such as supplied by Materials Electronic Products Corporation in Trenton, New Jersey are suitable) is sandwiched tightly between the top of block 130 and disk 126. The lower part of block 130 defines a plurality of downwardly extending heat-dissipating fins 132.

The components of chilling assembly 124 are secured together by four 90°-spaced bolts 133 with shanks passing through clearance holes 134 in block 130 to thread into clamping ring 127 as shown in FIGURE 3. Assembly 124 is in turn secured to the undersurface of upper shell 12 of the outer housing by four 90"-spaced bolts 135 (the heads of which are accessible through openings 136 in the hot sink block) having shanks which pass through clearance holes 137 in the clamping ring to thread into bosses 138 at the bottom of upper shell 12 as shown in FIGURE 5.

A thermally controlled variable-speed fan 140 (FIGURE 4) is secured to base panel 14, and slides upwardly into a cavity formed at the lower end of outer-housing lower shell 13 when the base panel is installed. An apertured air-outlet grill 141 is supported on the lower shell adjacent the discharge side of the fan. A temperature sensor such as a thermistor 142 (other types of temperature transducers such as a self-generating thermocouple are of course also suitable when used with compatible circuitry) is secured to the hot-sink block, and is coupled to speed-control circuitry in fan 140 by a cable 143. Temperature may also be sensed at other points in or external to the system such as at the module, at the cold sink, in the body of chilled water (the latter approach having the disadvantage of penetration of the tank by the sensor) , or in the room air surrounding the system. Outside room air is drawn by the fan through a plurality of inlet slots 144 (FIGURE 2) formed through base panel 14 to pass over and draw heat from fins 132.

Fan 140 is of a commercially available type (suitable units are available from Comair Rotron, Inc., in San Ysidro, California, or Sanyo Denki Co. Ltd., in Japan) which regulates fan speed according to the temperature sensed by thermistor

142. Fan speed is thus automatically diminished as the temperature of the hot sink block decreases, when water in the tank has been chilled or the room-air temperature becomes colder. Fan speed is correspondingly increased when a higher rate of heat dissipation is needed out of the tank. The control circuitry of the fan can be adjusted to match a specific range of fan speeds with a specific range of sensed temperatures. Alternatively, the speed control circuitry can be built onto a circuit board. Thermistor 142 would be connected to the circuitry to regulate the amount of current supplied to fan 140. Twelve-volt dc power is provided to thermoelectric module 131 and fan 140 by a transformer and rectifier assembly 143 (FIGURE 3) secured to base panel 14 and positioned within a cavity 145 formed in the bottom of lower shell 13 of the outer housing. The transformer is connected to a standard ac power outlet, and cabling from the assembly 143 to the thermoelectric module and fan is omitted from the drawings for clarity.

The thermoelectric module operates in a conventional way to draw heat from the cold sink disk and hence from water in the tank through plate 30 (acting as a kind of secondary cold sink which is tightly positioned in face-to-face contact with the upper surface of the cold-sink disk) to be dissipated to outside room air by fins 132 which are cooled by air sucked by the fan through base-panel slots 144 into the plenum surrounding the fins.

Though the control of cooling action is preferably provided by varying the fan speed (and thus reducing fan noise during "idling" operation when the tank water has been fully chilled) , an acceptable addition or alternative is to vary the current supplied to the thermoelectric module in response to varying heat loads. FIGURE 15 illustrates a typical arrangement of conventional circuit elements for controlling the operating level of the thermoelectric module. A transformer, full-wave rectifier, and smoothing capacitor form a power supply 147 for converting ac line voltage to direct current. A constant-speed fan motor 140 is connected across the power supply, and a low-dropout voltage regulator 149 (a Texas Instruments LT1084C regulator is suitable) in series with a thermoelectric module 131 is also connected across the dc output of the power supply. Temperature at a point in the system is sensed by a transducer such as a thermistor 151 which controls regulator 149 to vary the voltage, and hence current flow to module 131. In use, thermoelectric chilling assembly

124 forms an ice block 155 (shown in phantom line in FIGURE 4) in the bottom of the tank for rapid chilling of room-temperature water admitted from the upper chamber into the lower chamber. Thermistor 142, positioned in the hot sink, the cold sink, or elsewhere in the system provides feedback to fan 140 and/or thermoelectric module 131 to control the size of ice block. Water is dispensed through spigot 105, and temperature of the dispensed water can be adjusted by rotating intermediate sleeve 91 of the valve assembly. The intermediate sleeve has sufficient frictional resistance to rotation to maintain a desired preset position. A mixture of warmer and chilled water is provided by positioning the sleeve as shown in the proper manner. If only warmer water is needed, the sleeve is rotated to the position shown in FIGURE 14 with lower port 87 of the outer sleeve blocked, and upper port 86 fully open. Clockwise rotation of sleeve 91 to a position opposite that shown in FIGURE 14 blocks the upper port, and permits chilled water to be dispensed through the lower port.

A significant advantage of the invention is the ease of removing tank 24 and thermal-barrier assembly 35 for periodic dishwasher cleaning. Disassembly involves removal of the water bottle, release of latches 46 and upward withdrawal of the thermal-barrier assembly. The thus undamped valve assembly 73 can then be pulled outwardly within outer tube 74 out of engagement with tank 24 so the tank can be withdrawn from the outer housing. Reassembly involves only a reversal of these steps. The general arrangement of the tank, thermal-barrier assembly, and associated latches make the chiller system well adapted for mounting of a probe used to open resealable caps which are now available for bottled-water containers. To maintain good cooling efficiency, it is important that stainless-steel plate 30 forming the sealed bottom of the tank be clamped in intimate face-to-face contact with the upper surface of cold-sink disk 126. A degree of resiliency is provided in the system to accommodate tolerance errors of the plastic and metal parts by thick gasket 32 which is only partially compressed when clamping screws 31 are fully seated. Further compression of the gasket permits an "over center" action of clips 57, and the restoring force exerted by the gasket urges plate 30 against the cold-sink disk. The desired resiliency of the system can also be provided by using a resilient spring-loaded mounting for the thermoelectric chilling assembly.

A second embodiment of the present invention is illustrated in FIGURES 16-20. Elements in common with the first embodiment share the same reference numbers.

The second embodiment includes thermal barrier 35' . Thermal barrier 35' is different from thermal barrier assembly 35 of the first embodiment in that insulating disk 42 (FIGURE 1) and bottom cover 40 are eliminated. Instead, skirt 42b is provided around the periphery of bottom wall 37' . When the lower chamber is filled with water, air is trapped in space 42a to act as an insulator between the lower and upper chambers. The second embodiment includes a cold probe 230 instead of a cold plate as in the first embodiment. The cold probe is preferably made of aluminum. The cold probe 230 fits into a like- shaped protrusion in tank 24', such as plastic cover 232. The cold probe 230 is substantially cylindrical, but gradually tapers toward an upper tip thereof enabling cover 232 to be easily installed and fit snugly on probe 230, providing good surface-to-surface contact and good thermal conductivity. Furthermore, cold probe 230 includes a flattened surface 234 as shown best in FIGURE 17. Plastic cover 232 has a wide flange at the bottom which is employed to seal with bottom portion 25' via a locking ring illustrated in FIGURE 19. As a result, cover 232 becomes a part of the main tank and isolates water in the tank from cold probe 230 and enables simple cleaning of all surfaces in contact with the water. The wide flange has some resiliency to permit cover 232 to tightly engage cold probe 230 over a range of relative axial positions between cold probe 230 and main tank 24' and over a range of tolerances of the parts. The plastic cover 232 is preferably made of polypropylene or polyethylene. Cold temperatures cause shrinkage of the plastic cover 232, thus producing a tighter fit between probe 230 and cover 232.

As depicted in FIGURES 16 and 19, cover 232 fits through opening 26' in the bottom surface 25' of tank 24', thus allowing cover 232 to extend into tank 24'. Cover 232 fits onto tank 24' with engaging member 232a fitting into recess 24a formed in the lip of projecting portion 24c, which extends from the under surface of tank 24' (see FIGURE 19) . Grooves 24b are formed on the outer surface of projecting portion 24c. Locking ring 252 includes inner projections that interact with grooves 24b to lock cover 232 to tank 24' . An O-ring 250 provides a fluid-tight seal between cover 232 and tank 24'. O-ring 254 fits into recess 251 formed on the under surface of tank 24' interior to projecting portion 24c. Since cover 232 is formed separately from tank 24', cover 232 can be made of thinner plastic that provides better thermal contact between cold probe 230 and the water in tank 24' . Alternately, cover 232 can be molded integrally with tank 24' .

Cold probe 230 includes flattened face 234 defining an air pocket 236 between probe 230 and cover 232. Air pocket 236 is in the direction of valve assembly 73 from cold probe 230. The air pocket 236 also extends above probe 230 as shown in FIGURE 16. Air pocket 236 acts as an insulator between the cold probe and the plastic cover. Due to the presence of air pocket 236, the ice block that forms around cover 232 is thinner near flattened face 234. Since the thickness of the ice that forms on cover 232 proximate face 234 is less than the thickness over the remainder of cover 232, ice will not build up enough to interfere with the action of proportioning valve assembly 73 or the flow of liquid in the area around the valve assembly 73.

To facilitate initiation of ice block formation, sleeve 232a may be provided around a portion of cover 232. Sleeve 232a provides a small space adjacent to cover 232 that is free from convection currents that hinder initiation of ice block formation. The same effect can be achieved by extending the lower flange of cover 232 or by extending bottom portion 25' of tank 24' to create a space adjacent cover 232 where convection currents are reduced.

As shown in FIGURES 17 and 18, cold probe 230 contacts thermoelectric module 131. Washer 242 surrounds module 131a and provides a moisture seal to protect the module. A styrofoam insulator ring 244 rests on top of and provides additional pressure for sealing washer 242, and surrounds the base of cold probe 230. Cold probe 230 is secured to heat sink

246, which includes fins 248, as shown in FIGURES 17 and 18. Thermoelectric module 131 is disposed between the bottom surface of cold probe 230 and the upper surface of heat sink 246. Fins 248 of heat sink 246, in conjunction with fan 140, serve to dissipate heat from the module 131. Cold probe 230 is secured to heat sink 246 by a plurality of screws 250. For example, two screws 250 hold heat sink 246 to cold probe 230, with the screws 250 penetrating from the underside of heat sink 246 into cold probe 230. Bolts 133 hold the heat sink 246 to bosses 139 in the lower end of upper shell 12.

A cold side temperature sensor such as thermistor 274 is mounted in cold probe 230. An overtemperature sensor, such as thermistor 272, is mounted on a circuit board, on heat sink 246 or at other locations.

The circuit shown in FIGURE 20 is used to control the second embodiment. The circuit is mounted on a printed circuit board located in the base of the lower shell 13 adjacent the heat sink 246. The dispenser is plugged into a wall outlet to provide power to power supply 147. The transformer and rectifier turn the input ac power into dc power. Control logic 270 includes a differential amplifier that compares the voltage across the cold side thermistor 274 with a reference voltage. When the system is first started, thermistor 274 is at room temperature, and thus thermoelectric module 131 is driven at full power to reduce the temperature of the cold probe 230. As the temperature of the cold probe 230 decreases, the output from the differential amplifier decreases and less current is provided to thermoelectric module 131. In the preferred embodiment, the reference voltage is selected so that thermodynamic equilibrium is achieved when thermistor 274 is at about 20° F. The equilibrium temperature, 20°, is used by way of example only. The actual temperature used will depend on the size of the fluid reservoir, the amount of insulation around the reservoir, the size and shape of the probe, and other factors.

Overtemp thermistor 272 is used primarily to cut off the circuit if the system overheats. The voltage across overtemp thermistor 272 is compared to a reference voltage in a differential amplifier. When the voltage across thermistor 272 indicates a temperature greater than a predetermined maximum, such as 150° F, the differential amplifier causes the thermoelectric module 131 and fan 140 to shut off.

Fan speed control 275 is also a differential amplifier, which compares the voltage across cold side thermistor 274 with a reference. As the temperature of the thermistor 274 begins to approach the equilibrium temperature, such as 20°, fan 140 slows down. However, fan speed control 275 is arranged so that the fan never stops in order to prevent the fan from stalling. Of course, fan 140 does stop in response to overtemp thermistor 272. Thus, cold side thermistor 274 allows control logic 270 to control the size of the ice block that forms on cold probe 230 by regulating the thermoelectric module 131 and fan 140. In general, as the temperature of the cold probe 230 approaches the equilibrium temperature, e.g., 20°F, the speed of the fan 140 and the current to thermoelectric module 131 are decreased. One manner of decreasing the output to the cold probe is to first cut the fan speed and then decrease the power supplied to thermoelectric module 131. It is equally possible to simultaneously reduce the speed of the fan and the power supplied to the thermoelectric module 131. Alternatively, the fan speed can be kept constant and the power supplied to the thermoelectric module 131 can be reduced.

Like the first embodiment, the second embodiment is easy to disassemble, and can be cleaned by taking the dispenser apart. The main tank 24' may be removed by unfastening latches 46' and removing thermal barrier 35' . In the preferred embodiment, three latches 46' are provided although any number could be used. This releases valve assembly 73 which can then be removed. Then main tank 24' can be removed with cover 232. As described above, cover 232 can be removed from main tank 24' by turning locking ring 252.

Latch 46' is illustrated in FIGURES 21A- 21D. Latch 46' is attached to the top of sidewall 36' of thermal barrier 35' and is continuous therewith. Latch 46' includes movable member 261, which connects with sidewall 36'. Movable member 261 has a T-shaped end, formed by portions 262 and 264. Extending from the upper wall of outer housing 11 is projection 260, which tightly engages with portion 262. Latch 46' is configured so as downward and outward pressure on projection 264 releases latch 46' .

There has been described a thermoelectric water-chiller system which provides efficient cooling of bottled water for personal consumption and use, with quiet, reduced-noise operation after the water has been fully chilled. By reducing fan speed as the water becomes cool, less dust and other foreign matter collect on the heat sink so that cooling performance is maintained for a longer period of time. The system is designed to enable ready and simple disassembly for periodic cleaning. The system is not restricted to use with bottled water, and can be adapted for water-treatment systems of the point-of-use type. For example, the present invention may be employed with filter systems and can be used to cool filtered water. Also, water fountains, such as those found in offices, schools, etc., may utilize the present invention to chill the water to be dispensed therefrom. Furthermore, features found in either embodiment may be substituted in the other embodiment within the scope of this invention.

Claims

WHAT IS CLAIMED IS:

1. A fluid chiller system, comprising: a housing; a tank supported on and extending within said housing; a barrier defining an upper chamber and a lower chamber in said tank, said barrier allowing fluid in said upper chamber to flow into said lower chamber,* an adjustable proportioning valve mounted on said housing and coupled to said upper and lower chambers for dispensing variable proportions of fluid from said upper chamber and fluid from said lower chamber; and a cooling assembly having a cold sink in heat exchange relationship with said lower chamber.

2. A system as claimed in claim 1, wherein said barrier includes a locking means secured thereto and extending therefrom and adapted to be in releasable engagement with an end of said valve interior to said tank.

3. A system as claimed in claim 2, wherein said locking means includes a wall structure shaped to define in combination with a sidewall of said tank a passage for fluid from said upper chamber to said proportioning valve.

4. A system as claimed in claim 1, wherein said cooling assembly includes a heat sink and a thermoelectric module positioned between and in contact with said cold sink and said heat sink.

5. A system as claimed in claim 1, wherein said cooling assembly includes a metal plate formed at a bottom surface of said lower chamber.

6. A system as claimed in claim 1, wherein: said cold sink includes a cold probe having an elongated shape,* and said tank includes a cover over said cold probe for transmitting a cooling effect of said cold probe to fluid in said lower chamber, said cover extending into said lower chamber from a bottom surface of said lower chamber.

7. A system as claimed in claim 6, wherein said cold probe and said cover define an insulation space therebetween extending over a portion of said cold probe, said insulating space faces said proportioning valve.

8. A system as claimed in claim 7, further comprising a thermoelectric module positioned in contact with said cold probe.

9. A system as claimed in claim 1, wherein said barrier is constructed and arranged to be removable from said housing, said barrier having an opening disposed therein through which fluid drains from said upper chamber to said lower chamber.

10. A system as claimed in claim 9, further comprising a latch at an upper end of said housing for releasably securing said tank and said barrier to said housing.

11. A fluid chiller comprising: a tank; a cold sink; and a thermoelectric module attached to said cold sink, wherein said tank includes a cover over said cold sink, said cover forming a projection in said tank and permitting heat from fluid in said tank to be transmitted to said cold sink, said cover being fluid tight with said tank.

12. A fluid chiller as claimed in claim

11 further comprising a main housing, said tank with said cover being removable from said main housing.

13. A fluid chiller as claimed in claim

12 further comprising a removable dispensing means extending through said tank.

14. A fluid chiller as claimed in claim 12 further comprising a latch for releasably fastening said tank in said main housing.

15. A fluid chiller as claimed in claim 14 further comprising a barrier in said tank dividing said tank into first and second chambers, said barrier having an opening disposed therein through which fluid drains from said upper chamber to said lower chamber.

16. A fluid chiller as claimed in claim

11 further comprising means, adjacent said cover, for facilitating initiation of formation of an ice block around said cover.

17. A fluid chiller system comprising; a tank; a cold sink in heat exchange relation with fluid in said tank; a heat sink; a thermoelectric module disposed between said cold sink and said heat sink; a fan blowing air over said heat sink; means for monitoring the temperature of said cold sink; and means responsive to said monitoring means, for controlling current to said thermoelectric module and the speed of said fan so that the temperature of said cold sink approaches a predetermined temperature.

18. A fluid chiller as claimed in claim 17 wherein said controlling means includes means responsive to said monitoring means for beginning to reduce the speed of said fan before beginning to reduce current to said thermoelectric module as the temperature of said cold sink approaches said predetermined temperature.

19. A water-chiller system comprising: a tank; a housing supporting said tank; a thermoelectric cooling assembly, said assembly having a cold sink in heat exchange relation with fluid in said tank, a heat sink, and a thermoelectric module sandwiched between and in contact with said cold sink and said heat sink to transfer heat from said cold sink to said heat sink; and means for controlling heat-transfer rate through the cooling assembly, including a temperature sensor disposed in said cold sink.

20. A fluid chiller comprising: a main housing; a removable tank secured to said main housing via at least one latch, said tank having a first chamber and a second chamber; a cold sink in heat exchange relation with said second chamber of said tank; and a removable dispensing means adjustable to allow at least one of fluid from said first chamber and fluid from said second chamber to exit said tank.