The present invention relates to a beverage cooler having an in-line operating cooling unit for instant cooling of beverage flowing through the same, comprising a cooling container having an inlet pipe and an outlet pipe for feeding the beverage to and from the cooling container, respectively, and a cooling tube located inside the cooling container. The beverage cooler can either be built into a refrigerator, for home use or for commercial use, or be formed as a self-contained unit.

The invention also relates to a refrigerator comprising a beverage cooler as well as a method for cooling beverage.

Background of the invention

Cool drink dispensers or beverage coolers are known since long time. Inter alia, it is known to provide refrigerators with a water tank, being connected to a water supply pipe, for cooling of the water in the tank and, on command, dispense cool water through a dispenser built-in in the door of the fresh-food compartment. The refrigerator can also be provided with a second tank for adding carbon dioxide to the water to allow dispensing of sparkling water through the dispenser. There are several disadvantages with a cool drink dispenser of this kind. For example, it is bulky, a relatively long time is needed for restoring the cooling temperature of the water after the tank or tanks have been partly or completely emptied and refilled again, and there could be a risk for formation of mould and bacteria in case the dispenser is used only sporadic and the water is stored for long time in the tanks.

To overcome these drawbacks, the present applicant has developed a novel cool drink dispenser, as presented in the filed but not laid open European patent application no. 07105281.5. This cool drink dispenser comprises an in-line operating cooling unit connected to a supply source for beverage, typically water. In one embodiment the cooling unit comprises a cooling pipe , through which the beverage flows, and heat accumulating material, such as paraffin or any other similar material surrounding the cooling pipe, absorbs heat from the beverage so as to cool the beverage to a predetermined tern- perature. To maintain the solid state of the heat accumulating material inside the tubular member, the cooling unit also comprises a cooling circuit, which is located in the heat accumulating material and through which a cooling fluid, such as cold air or any other gaseous or liquid cooling fluid is circulated. The cooling fluid can be cooled inside a freezer compartment of a refrigerator. The cooling circuit can also be formed as an evaporator containing a refrigerant. In a second embodiment the cooling unit does not comprise the internal cooling pipe. Instead, the cooling unit comprises a tubular body into which the beverage is fed. The tubular body comprises cooling means, which cools the beverage inside the tubular body such that the beverage will freeze to a semisolid, high-viscosity mixture of frozen beverage. By controlling the cooling means in a suitable way, it is possible to limit the percentage of beverage in the solid or semisolid mixture state to not exceed a predetermined maximum ranging between 50% and 90% of the maximum capacity of the tubular body. In this way it is possible to ensure free circulation of beverage inside the tubular body through the solid or semisolid frozen beverage, such that beverage at ambient temperature can mix with and partly melt the solid or semisolid frozen beverage mixture and flow immediately to a dispenser valve where it can be dispensed to a user. In one embodiment the cooling means is formed as a housing surrounding the tubular body and comprises electric fans, which on command can circulate a stream of cold air at a temperature below a freezing temperature for the beverage or a stream of warm air at a temperature above the freezing temperature. The cold air stream can be taken from a freezer compartment of a refrigerator, typically holding a tem- perature of between -25°C and 0 ⁰ C, whereas the warm air stream may be taken from a fresh-food compartment of the refrigerator, typically holding a temperature of between 0 ⁰ C and 15°C.

However, a cool drink dispenser according to EP 07105281.5 has some disadvantages. In order to prevent completely freezing of the beverage inside and maintain a free passage for the beverage through the cooling unit, it may be necessary to arrange heating elements, which can melt the frozen beverage when necessary. This will result in additional costs for the equipment and the introduction of a device that counteracts with the refrigeration process and thus may lead to increased power consumption. The above described second embodiment also necessitates the arrangement of a dedicated compartment in form of a housing surrounding the tubular body, which results in that the occupied space will increase. It also necessitates a precise sensing system for the formation of frozen beverage but prevent completely freezing of the beverage.

In an additional filed but not laid open European patent application no. 07114478.6 from the present applicant, is disclosed an alternative appliance for supplying cooled water or other beverage. This appliance comprises an airtight tank for temporarily storing the beverage and the tank is connected to a source, which supplies beverage continuously to the tank. I.e. as soon as cooled beverage is dispensed from the tank, the source supplies fresh, warm beverage to the tank such that it always will be completely filled by beverage. The tank is either made of elastically deformable material or is a rigid con- tainer housing a closed capsule made of elastically deformable material and filled with gas. In one embodiment, the tank is accommodated inside a cooling compartment, e.g. formed in a door of a refrigerator. In order to control the temperature of the beverage inside the tank within a desired temperature range, the appliance comprises a number of electric fans which, on com- mand, circulate inside the cooling compartment a stream of cold air, e.g. taken from a freezer compartment inside the refrigerator, or a stream of warm air, e.g. taken from a fresh food compartment in the refrigerator or from outside of the refrigerator. In this way the beverage inside the tank can be maintained at around the freezing temperature. Alternatively, the fans may be re- placed by an evaporator inside the cooling compartment. One disadvantage with such an appliance is that the control device for regulating the temperature of the beverage inside the tank, will be relatively complicated in order to maintain the temperature as close as possible to the freezing point and yet prevent completely freezing of the beverage and blocking of the tank, which would make it impossible to dispense beverage. Such a regulating including alternate warming and cooling could also lead to increased energy consumption. Another disadvantage associated with such an appliance is that it will require a relatively large space since the tank has to be enclosed by a cooling compartment to allow circulation of warm or cold air around the tank. In another embodiment, the tank is so designed that, even if ice is formed therein, it can expand in a radial direction when there is a sufficient pressure of liquid at its entrance, so as to allow liquid flow. Moreover, the tank may be designed such that some portions of the tank are positioned inside a cooling compartment while others are outside of the cooling compartment.

Summary of the invention

It is an object of the invention to improve in-line operating beverage coolers. More precisely it is an object to provide an in-line operating beverage cooler, which is space-saving and has a simple and inexpensive structure. At least this object is achieved by a beverage cooler according to claim 1.

The invention also relates to a refrigerator provided with an in-line operating beverage cooler and a method for cooling beverage having essentially the same object as above. At least this object is achieved by a refrigerator according to claim 13 and a method according to claim 14.

Accordingly, the basis of the invention is the insight that at least the above object may be achieved by providing a cooling container having an inlet and an outlet for allowing the beverage to flow through the container, and a cooling tube that is arranged inside the cooling container and through which a cooling fluid can be circulated. The cooling container is adapted to be positioned in an ambient temperature above the freezing point for the beverage, whereas the cooling fluid, circulated inside the cooling tube, is adapted to have a temperature which is below the freezing point for the beverage. In this way, when it is desirable to dispense cold beverage for drinking, the beverage can flow through the cooling container and pass by the cooling tube such that the beverage will be instantly cooled by the cooling fluid inside the cooling tube. Eventually, there will be formed a layer of frozen beverage around the cooling tube, whereas a free passage of non-frozen beverage always will be present in an area closest to a peripheral wall of the cooling container due to the ambient temperature being above the freezing point for the beverage. When a layer of frozen beverage is formed around the cooling tube, the frozen beverage will partly melt when warm beverage flows around the cooling tube as beverage is dispensed from the cooling unit. Accordingly, the frozen beverage around the cooling tube represents a cooling supply, which will contribute to the instant cooling of the beverage as it flows through the cooling container from the inlet to the outlet. Utilizing frozen beverage for cooling the warm beverage is advantage since a large amount of energy is required for transforming a substance in solid phase into liquid phase. Since the cooling container is located in an ambient temperature above the freezing point of the beverage, no heating means is required to ensure a free passage of non- frozen beverage through the cooling container. By a proper adaptation of the cooling effect to the size of the cooling container and the ambient temperature around it, it would be possible to find a proper balance which always will ensure a free passage of non-frozen beverage through the cooling container regardless of whether beverage is dispensed through the cooler during an extended time period or not. However, it can be advisably to provide some kind of regulating device to control the throughput of cooling fluid through the cooling tube, in order to restrict or interrupt the cooling effect when no beverage is dispensed from the cooling unit and to increase the cooling effect when an amount of beverage is dispensed. It would also be possible to arrange e.g. a fan to increase the air flow around the cooling container in case the beverage inside is in the risk of becoming completely frozen.

Within this overall idea, the invention can be realized in many different embodiments. The beverage normally being cooled in a cooler according to the invention is water and in that case the cooling unit preferably is connected to a water supply conduit, e.g. a conduit of a mains water network. However, it would also be conceivably to cool also other types of beverages with a cooler according to the invention, such as e.g. juice.

Moreover, the cooler according to the invention, can be arranged in a refrigerator having a freezer compartment, with a temperature typically rang- ing between 0°C and -25 ⁰ C, and a fresh food compartment with a temperature typically ranging between 0°C and 15°C. In this way the advantage is achieved that many of the means, which already is present in the refrigerator, can be utilized for realizing the invention. For example, the cooling container can be positioned in the fresh food compartment, which holds a temperature above the freezing point for water and the temperature is moreover essentially uniform and low which facilitates regulating and eliminates the need for any insulation around the cooling container. Additionally, the freezer com- partment can be utilized for cooling the beverage inside the cooling container, e.g. by transferring cold air from the freezer compartment through the cooling tube inside the cooling container. Alternatively, it would be conceivable to arrange the cooling tube as part of a closed loop filled with a cooling fluid, such as for example water having an anti-freezing additive in form of e.g. salt, al- cohol or glycol or a gaseous cooling fluid, and to circulate the cooling fluid through the freezer compartment, for cooling of the cooling fluid, and through the cooling container for absorbing heat from the beverage. Another possibility is to cool the inside of the cooling tube by using a thermosyphone or a heat pipe, in which a suitable refrigerant, in a loop or a single pipe, is made to eva- porate inside the cooling tube. The condenser of the heat pipe or thermosyphone could favourably be cooled by being in thermal contact with the evaporator of the refrigerator. The condenser of the thermosyphone or the heat pipe could also be cooled by an alternative means of refrigeration, such as for instance a thermoelectric refrigeration unit. A possible way for regulation of the temperature in the cooling tube may be performed in different ways, such as e.g. by measuring the temperature inside the cooling container a small distance from the cooling tube and to regulate a fan or a pump, which circulates the cooling fluid through the cooling tube. In an alternative embodiment the fan or the pump may be dispensed with if measures are taken to provide self-circulation of the cooling fluid from the freezer compartment to the cooling container and back again. In such a case, the regulating device may comprise a throttle valve, which controls the circulation of the cooling fluid.

Instead of combining the cooling unit with a conventional refrigerator having a fresh food compartment as well as a freezer compartment, it would be conceivable to combine it with a pure freezer if the cooling container is positioned outside of the actual freezer compartment, such as completely outside of the freezer or in a dedicated space inside a door or a wall of the freezer having a temperature above the freezing point. It is also possible, as in a hereinafter described and illustrated embodiment, to combine the cooling unit with a refrigerator having only a fresh food compartment by letting the refrigerant of the refrigerator cooling system circulate also through the cooling tube.

It would also be possible to form the beverage cooler as a completely self-contained unit. In such a case it is necessary to provide the beverage cooler with a refrigeration unit comprising for example a compressor and a condenser or alternative means of refrigeration such as thermoelectric cool- ing, thermionic cooling, magnetic refrigeration, thermoacoustic cooling, absorption cooling and adsorption cooling. If the cooling container is located in room temperature, it is advisable to provide it with an insulating layer to reduce heat absorption in the cooling container from the outside.

In order to increase the cooling effect, the cooling tube can be provided with cooling flanges. In a described and illustrated second embodiment, the cooling tube is provided with a cooling flange, which is spirally wound around the cooling tube and extends the entire distance between the outer surface of the cooling tube and the peripheral wall of the cooling container. In this way is formed a long, narrow and spirally shaped path for the beverage to flow be- tween the inlet and the outlet. Due to this is achieved an extremely effective cooling of the beverage, since the flow path is so long, the area of exposure to cold surfaces is so large and the flow through the cooling tube will be entirely turbulent, due to the high flow speed and the proximity to surrounding walls everywhere in the cooling container. To increase the turbulent flow, the surfaces of the cooling flange can be provided with irregularities. Also in this embodiment it is advantageous if the beverage closest to the cooling tube is frozen to ice 15, whereas a passage 17 of unfrozen beverage is maintained at the peripheral walls 16. Naturally, the invention can be modified also in many other ways within the scope of the claims. It is preferred that the cooling tube is located centrally inside the cooling container, preferably concentric with the cooling container. This is advantageous in that the formation of a layer of frozen beverage can occur around the entire cooling tube and a free passage of non-frozen beverage may be maintained closest to the entire inner surface of the cooling container. However, it would also be possible to position the cooling tube adjacent a portion of the inner surface of the cooling container, important is however that the outer cross sectional dimension of the cooling tube is sufficient smaller than the inner cross sectional dimension of the cool- ing container such that a free passage of non-frozen beverage always may be maintained somewhere in the cooling container. Generally, it is preferred to form the cooling tube as well as the cooling container with a circular cross section but also other cross sectional shapes would be conceivable. To increase the cooling capacity of the cooling tube, it can be provided with cooling flanges or the like around its periphery.

A beverage cooler according to the invention, can be combined with a refrigerator in many different ways, such as a refrigerator comprising a fresh food compartment and a freezer compartment, wherein the cooling container is positioned in the fresh food compartment and the cooling fluid in the cooling tube is cooled in the freezer compartment. As already mentioned, the beverage cooler can also be combined with a pure freezer if the cooling container is positioned outside of the freezer or in a dedicated space inside the door, in a wall or the like. In case the refrigerator do not contain any freezer compartment but only a fresh food compartment, it is possible to position the cooling container inside the fresh food compartment and let the evaporator of the refrigerator, or a branching from it, constitute the cooling tube.

Naturally, it is also conceivable to combine the beverage cooler with a carbonation device for mixing carbon dioxide into the beverage, e.g. a car- bonation device as disclosed in the EP-application 07105281.5 or any other suitable kind, to obtain a sparkling beverage.

Brief description of the drawings

An exemplary embodiment of the invention will hereinafter be described with reference to the accompanying drawings, in which: Fig 1 is a schematic perspective view of a refrigerator being provided with a beverage cooler according to the invention; Fig 2 is a schematic presentation of components of the cooling system for the refrigerator and beverage cooler according to fig 1 in form of a functional block diagram;

Fig 3 is an enlarged section through a cooling container of the bever- age cooler;

Fig 4 is an enlarged transparent perspective view of an alternative embodiment of the cooling container; and

Fig 5 is a longitudinal section of the cooling container in fig 4.

Detailed description of an embodiment of the invention

In fig 1 is illustrated a refrigerator 1 of which a door 2 is open for visibility of the interior of the refrigerator. The refrigerator is in this embodiment of the type having only a fresh food compartment 3, which has a temperature ranging normally between 0° C and about 8° C. Inside the fresh food com- partment, the refrigerator is provided with cooling radiators 4, through which a refrigerant is circulated in a conventional way known in the art, for cooling of the fresh food compartment. Also positioned inside the fresh food compartment is a cooling container 5 of a beverage cooler, according to the invention, and on the outer surface of the door is provided a recess 6, indicated with broken lines on the inside of the door in fig 1 , which contains a not shown beverage dispenser unit for dispensing cooled beverage to a user when desired.

Reference is then made to fig 2 in which the essential structure of the refrigerator cooling system and the beverage cooler is illustrated in form of a block circuit diagram. The fresh food compartment 3 of the refrigerator is indicated by a rectangle. The refrigerator cooling system comprises a compressor 7, which is positioned outside of the fresh food compartment. In the compressor, a gaseous refrigerant fluid is compressed, which has to result that the temperature of the refrigerant is increased. The refrigerant is then passed through a condenser 8 where the warm gas is cooled and condensed to a liquid phase. The liquid refrigerant then flows through an expansion valve 9 where the pressure is lowered. This has to result that the liquid refrigerant at least partly will return to a gaseous state. The conversion of the refrigerant from liquid phase to gaseous phase will lower the temperature of the refrigerant considerably. Immediately after passing the expansion valve, the refrigerant passes the wall of the refrigerator cabinet and flows into the cooling container 5 of the beverage cooler according to the invention. The cooling container 5 is provided with an inlet 10 and an outlet 11 to admit filling and discharging of beverage to be cooled into and from the cooling container, respectively. In the embodiment illustrated, the beverage to be cooled is water, so for this reason the beverage inlet is connected to a water mains network at a water net connection 12. The outlet is connected to the water dispenser unit 13 in the outer surface of the door. However, it is to be understood that also other kinds of beverages could be cooled by means of the beverage cooler according to the invention. In that case the inlet tube is connected to a container containing the beverage instead of being connected to the water mains network. To achieve cooling of the beverage, a cooling tube 14 is extended through the cooling container through which the refrigerant flows, i.e. the cooling tube functions in this embodiment as an evaporator, which cools the beverage flowing around it.

The cooling tube is connected in series with the evaporator in form of the cooling radiators 4 of the refrigerator cooling system, which can be of a generally known type comprising additionally valves, sensors, control equipment, cooling flanges and the like, so as to accomplish cooling of the inside air of the fresh food compartment 3 in a desired degree.

Referring thereafter to fig 3, in which a first embodiment of the cooling container 5 is illustrated in a longitudinal section. As is apparent, the cooling tube 14 is positioned centrally in the cooling container 5 and extends completely there through. In a practical embodiment, the cooling tube 14 can preferably be formed with cooling flanges and the like for increased cooling capacity. During operation it is most likely, and also desirable, that a layer of frozen beverage will be formed in the region closest to the cooling tube, as is illustrated by the layer 15 in fig 3. However, in the region closest to peripheral walls 16 of the cooling container, it is intended that the beverage will be maintained in an unfrozen state, as is indicated at 17. In this way a passage of unfrozen beverage is formed such that warm beverage may flow in through the inlet 10, be cooled by the refrigerant circulating through the cooling tube 14 and the frozen beverage 15 around the cooling tube and flow out in form of cooled beverage through the outlet 11. If the beverage cooler is allowed to form frozen beverage around the cooling tube, the further advantage is achieved that the cooling container 5 will contain stored cooling capacity in form of frozen beverage, which can be made use of when warm beverage is flowing in through the inlet in order to achieve instant cooling of the beverage. A control device for regulating the cooling effect of the cooling container may in a simple embodiment comprise a temperature sensor located in the pas- sage 17 of unfrozen beverage in the cooling container, which by means of a control circuit regulates the pressure drop in the expansion valve 9 and hence the cooling effect of the cooling tube 14. For example, the control device may be set to maintain the temperature of the unfrozen beverage 17 one or a few degrees above the freezing point for the beverage. Reference is then made to figs 4 and 5 of the drawings, in which a second embodiment is illustrated in a transparent perspective view in fig 4 and a longitudinal section in fig 5. In this embodiment, the cooling tube 14 is provided with a cooling flange 18. However, this cooling flange does not extend only a short distance above the outer surface of the cooling tube, as is customary in connexion with cooling and heating appliances. Instead, the cooling flange is spirally wound around the cooling tube 14 and extends the entire distance between the outer surface of the cooling tube and the peripheral wall 16. In this way is formed a long, narrow and spirally shaped path 19 for the beverage to flow between the inlet 10 and the outlet 11. Due to this is achieved an extremely effective cooling of the beverage, since the flow path is so long, the area of exposure to cold surfaces is so large and the flow through the cooling tube will be entirely turbulent, due to the high flow speed and the proximity to surrounding walls everywhere in the cooling container. Also in this embodiment it is advantageous if the beverage closest to the cool- ing tube is frozen to ice 15, whereas a passage of unfrozen beverage is maintained at the peripheral walls 16.