WO1998001714A1

WO1998001714A1 - A device for the production of ice cubes

Info

Publication number: WO1998001714A1
Application number: PCT/NO1997/000174
Authority: WO
Inventors: Dag F. Lilleaas
Original assignee: Lilleaas Dag F
Priority date: 1996-07-04
Filing date: 1997-07-04
Publication date: 1998-01-15
Also published as: NO303191B1; NO962830D0; NO962830L; AU3363797A

Abstract

Ice cubes are produced in a machine wherein water is distributed in a layer over an inclined freezing plate (14) which is supplied with means for providing cold or heat. Water which is preferably boiled or sterilized is distributed evenly in at least one channel (28) in the longitudinal direction of the inclined freezing plate's (14) bottom plate (29). By means of circulation of a cooling medium in one or more transverse channels (30), arranged at a distance apart, a freezing is effected of ice in the zones over the channels (30) and the gradual build-up of ice cubes at a distance apart and limited by the channels' (28) longitudinal walls (35). On achieving a desired ice cube thickness and a corresponding lowering of the temperature on the bottom plate (29) a heating process is initiated which provides a heating from transverse and/or longitudinal heating zones/channels. This heating causes a loosening of the ice cubes which thereby slide down along the inclined plane, whereupon the supply of heat is stopped and the freezing process is repeated.

Description

A device for the production of ice cubes

The invention concerns a device for the production of ice cubes in a machine, where water is distributed in a thin layer over an inclined freezing plate, the bottom of which is supplied with means for providing cold or heat. The invention especially concerns a device for the production of ice cubes in small portions, intended for use in small establishments and in households.

There are a number of known methods and devices for such ice cube production. Ice cube machines of this kind have been used especially in hotels and restaurants where the consumption of ice cubes is high. Such machines are intended for more or less continuous operation, the machine usually being supplied with water directly from the mains and ensuring a regular replenishment of a storage container for the ice cubes. In the freezing process, water is distributed over a relatively large freezing surface, which means that a relatively large refrigeration system must be used for forming ice simultaneously over the entire surface. Most of the known devices of this type are relatively large and expensive and not particularly suitable for private households. Ice cube machines have also been developed in connection with refrigerators/freezers, where the unit's refrigeration system is also utilised for the formation of ice cubes.

In US patent no. 4 412 420 there is disclosed a machine for producing ice cubes where water is circulated along a freezing plate in a machine. The plate is equipped on both sides with a lattice of channels for circulation of a cooling medium and water pipes, thus forming hollows or moulds. The plate is placed vertically below a vessel with water from which water is supplied to the plate. Ice cubes will thus be formed in the hollows on both sides of the plate. When the ice cubes have to be released, the cooling medium is replaced with a heating medium, the water pipes are filled with water and this heating process causes the ice cubes to work loose and fall down into a container under the freezing plate. US patent no. 4 357 807 describes a machine for producing ice cubes where water runs over a inclined, flat freezing plate, where tubes are provided for the cooling medium on the bottom, thus forming a layer of ice on the plate. After a certain operating period the cooling medium is replaced with a heating medium, thus causing the plate to be heated and the bottom layer of ice melts, with the result that it slides down on a net consisting of a tube with a heating medium, which will divide the sheet of ice into cubes by melting the sections which are in contact with the net.

In both US patents the water which does not freeze is recycled to the freezing plate's upper area. There is further disclosed in DE 2517942 a method for producing ice cubes where the ice cubes are made in moulds which are surrounded by tubes for a cooling medium. The ice cubes are released by means of hot water and forced out of the moulds by water under pressure which is introduced at the bottom of the moulds. This water is employed in a next stage for the formation of new ice cubes.

Most of the ice cube machines on the market to-day are, as mentioned above, connected to the water mains, since the water which has to be frozen should not be polluted before entering the ice making machine. Moreover, connection to the mains permits a process to be achieved which is as automatic as possible. A disadvantage of this kind of connection, however, will be that impurities which exist in the mains system will also enter the ice making machine. Furthermore, there is often a certain amount of air in the mains water, which can lead to air bubbles in the ice cubes which are formed.

It is an object of the present invention to provide a method and a device which will permit the production of ice cubes in a machine of small size and low weight. At the same time the capacity during production should be large enough to satisfy the normal requirements of an ordinary family, and the machine should be so reasonable to purchase that it will become an alternative in the consumer goods sector. In this connection the method should be capable of being implemented with low energy consumption in a machine which is service-friendly and mobile and does not require to be connected to the water mains while at the same time employing small quantities of cooling medium.

These objects are achieved with a device which are characterized by the features presented in the patent claims.

In the invention use is preferably made of boiled or sterilised water, thereby avoiding the inclusion of impurities and any bacteria from the mains, while at the same time ridding the water of excess oxygen or air, thus ensuring that the ice cubes which are formed will be homogeneous and transparent. With the terms "boiled" and "boiling" it is here and in the following ment water which has been heated or is heated to a temperature near the boiling temperature, i.e. a temperature higher than approx. 80°C. The boiled or sterilised water may either be filled directly from a storage container or as preferred, at the start-up in a suitable container in the circulation circuit, before starting the machine, while otherwise water is boiled in the actual ice cube machine during the operation thereof.

The device according to the invention is intended for free-standing use, i.e. it is normally not connected to the water mains, but instead is equipped with a container which is filled with water. The machine can thereby be designed as a small, light machine which is suitable for use in private households. Despite the energy consumed in boiling water, the total energy consumption is low, since, before being added to the recycling circuit, the boiled water can be used as a heating medium for heating the bottom plate for the release of ice cubes.

After the recycling over the freezing plate has been in progress for a certain period, and the desired size achieved for the ice cubes, water from a storage tank is supplied to a heating device where the water is heated or boiled. During the boiling process steam may be developed, which together with any air in the water conveys the hot water up through an expansion member in the form of a container and/or a manifold, and on through a tube to heating channels in the bottom plate. In the expansion member the steam and the air will to some extent be released from the water and flow in an introductory stage through the heating channels. This will ensure the removal of any lumps of ice which have formed in the heating channels during a previous freezing cycle. Boiled water then flows through the heating channels, thawing the ice layer located closest to the bottom plate, whereupon the ice will slide down into a collecting container, e.g. a tray, where it can be collected by the consumer. The freezing process may be of any type where a cooling medium is employed. This may be any kind of medium, including gases and liquids, which are normally employed in refrigeration units, including absorption cooling. The length of the freezing plate, in the direction of the inclined surface, from the water supply zone to the lower end is preferably substantially longer than the largest dimension of the desired ice cubes. The plate will only be cooled in defined, for example ribbon-shaped, zones which extend across the direction of fall and which are separated by heating zones, thereby providing separate ice cubes of the desired dimension.

In the method according to the invention, where the water preferably comes from a storage tank provided inside the actual machine, a separate water pipe system is avoided along with the costs associated thereto. In addition sterile water is obtained, while at the same time steam and hot water are obtained for loosening the ice cubes in the freezer channel.

Further features of the invention will be presented in the claims and the following description of an embodiment of an ice making machine according to the invention with reference to the drawing, in which: fig. 1 is a schematic illustration of the production process, fig. 2 is a perspective view of a freezing element with five parallel freezing channels, which can be employed in accordance with the invention in an ice cube machine, fig. 3 is a similar perspective view of a second embodiment, fig. 4 is a section through the freezing element, along line III-III in fig. 2, and fig. 5 is a similar section of the embodiment in figure 3.

In order to facilitate understanding, the same reference numerals are used for corresponding parts in all the figures.

In fig. 1, which is a purely schematic block diagram, the numeral 1 indicates a filling device for water. This may advantageously be funnel-shaped in order to facilitate filling. The water passes through a filter 2, which is intended to remove particles and any other substances which are dissolved in the water, depending on the filter type. The filter may be of a type which is either cleaned after a certain period of use or is replaceable. From the filter the water continues down into a storage tank 3 whose size is intended for a certain period of ice cube production. From the storage tank a tube goes to a coupling 4, which normally may be a Y tube or a T tube. From the coupling a tube passes through a non-return valve 5 to a heating device in the form of a boiling element 6. From the boiling element a tube 7 continues to an expansion member 27 in the form of a container and/or a manifold, and thereafter to a system for distribution of a heating medium. In figure 1 this system is illustrated as a loop-shaped channel system, but it may also consist of a plurality of separate channels. The channels may be provided horizontally and/or vertically. Alternative designs are described below. The channels are arranged in close contact with a plate-shaped freezing element 14, where the formation of ice cubes is to take place. The outlet of the channel(s) is connected with a tube or the like which forms a connection to a collecting container 17 which is placed under a collecting tray 16 for ice cubes. The collecting tray has a perforated bottom. From the collecting container 17 a tube leads back to the coupling 4 via a non-return valve 18, and a second tube leads to a recycling vessel 9 via a non-return valve 8. A tube connects the recycling vessel 9 with a pump 10, which in turn is connected via a return tube 1 1 to a distributor tube 12 which is located at the top of the freezing element 14. Choice of pump type will be dependent on the location of the pump 10 in the circuit. In the example a supply pump is employed, but for a different location an extraction pump may also be employed. In the tube 1 1 there is further provided a choke body 13. Under the freezing element there is located a collecting tray 15, from which a tube leads down to the recycling vessel 9. A recycling circuit is thereby formed for water from the recycling vessel 9, through the pump 10, via the return tube 11 to the distribution tube 12, down along the freezing element 14, on to the collecting tray 15 and back to the recycling vessel. The figure also illustrates an outlet 26 which can be used for emptying and cleaning the machine.

The plate-shaped freezing element 14 is illustrated in more detail in a first embodiment in fig. 2. It consists of five channels 28 located beside one another with a common flat bottom plate 29 which is inclined, the channels' longitudinal axes being parallel to the direction of fall for the inclined bottom plate 29. The five longitudinal channels 28 are separated by partitions 35 and extend from the bottom plate's upper edge 33 to the plate's lower edge 34. The partitions 35 are designed as triangular elements with the greatest width at the bottom plate 29, with the result that the channels have inclined lateral walls. On the underside the bottom plate 29 there are indicated with broken lines heating channels 32 and evaporator tubes 30 for cooling medium in direct contact with the plate. The heating channel system is composed of a forward and backward-moving loop of heating channels 32, which may have a slight slope in the through-flow direction in order to ensure good drainage. An evaporator, which forms part of a cooling medium circuit 22, is permanently connected to the freezing element 14. In the illustrated embodiment the evaporator and the freezing element are connected, e.g. by soldering, thus forming one unit. A second embodiment is illustrated in figure 3. The actual freezing element 14 is designed in the same way as in figure 2, with a bottom plate 29 and channels 28 separated by the partition walls 35. Instead of a construction with heating channels 32, in this case the triangular partitions 35 are employed for transport of the heating medium. The triangular interior space may either be used directly as channels, attached on top of the plate or be equipped with internal tube elements designed in an appropriate manner. The plate 29 may also be designed by having the partitions directly pressed out of the plate material, the channels being closed with strips of plate on the underside. For supply of medium a distributor or manifold is employed which simultaneously constitutes the expansion member, the reference numeral 27 being retained for this expansion manifold.

A third, not shown alternative is to employ a combination of the two embodiments which are described above, i.e. both heating channels and partition channels. In the invention a standard refrigeration unit is employed, which is operated by a cooling medium and which consists of a compressor 19, a fan 20, a condenser 21, a drying filter 23, a choke body (e.g. in the form of capillary tubes or a thermostatic expansion valve) 13, the evaporator in the freezing element 14 and a heat exchanger 24. The actual freezing process for the ice cubes is of a conventional nature and is therefore not described more closely. The cooling medium circuit 22 consists of parallel evaporator tubes 30 which are connected in forward and backward-moving loops in close contact with the underside of the bottom plate 29. The evaporator tubes 30 for cooling medium thus extend across the direction of fall, and will be located between the heating channels 32 in the embodiment in figure 2. The channels 30 form transverse freezing zones 31 in the freezer channels, located at a sufficient distance apart to prevent these freezing zones from merging with one another, but being separated by warmer zones where the water does not freeze. In fig. 1 three channels 30 and thereby three freezing zones 31 are shown, but this number may be both larger and smaller.

When using ice cube machines, the storage tank 3 is first filled by hand. At the same time it is an advantage, but not strictly necessary, to fill boiled water in the collecting container 17, thus enabling the recycling process, which is discussed in more detail below, to be initiated more quickly. The reason why the water which is filled should be boiled in advance is that it forms part of the recycling circuit from the start-up point, without passing through the boiling element 6. In the subsequent description of the freezing process, it will be assumed that boiled water is filled in the collecting container before starting the ice cube machine. The compressor 19 is started and the evaporation temperature in the evaporator tubes 30 in the cooling circuit 22 causes the temperature in the transverse zones 31 on the bottom plate 29 to be sufficiently low to freeze the water into ice cubes. At the same time the pump 10 is started, thus conveying water from the collecting container 17 through the recycling vessel 9 to the distributor tube 12. The water is passed out through suitable openings in the distributor tube 12 and trickles down over the freezing plate 14. When it passes the zones 31 the water is cooled. From the collecting tray 15 the water runs on to the recycling vessel 9, whereupon it returns to the pump 10 and is again passed to the distributor tube 12. After a period of time the temperature of the water becomes so low that the water freezes to ice on the bottom plate 29 in its freezing zones 31, thus gradually forming ice in cubes whose length and breadth are determined by the width of the channels 28 and the size of the zones 31.

After a period a thermostat 25, which is provided in connection with the freezing element 14, detects a lowering in the temperature of the bottom plate 29, thus indicating that the ice cubes have reached a certain size. The thermostat then causes the power in the boiling element 6 to be switched off. The boiling element 6 receives water from the storage tank 3 and brings it to boiling point. The boiling water is transported therefrom to the expansion container/manifold 27. Steam and some air will be released here and flow on to the heating channels 32, or to the channels of the partitions 35. The steam and the hot air will thaw any ice crystals which may be located in the heating channels 32 and/or the channels of the partitions 35. After boiling for some time the water will fill the expansion container/manifold and consequently flow on through the heating channels 32 and/or the channels in the partitions 35. The bottom plate 29 is heated, thus causing ice cubes which have been formed over the freezing zones 31 to loosen and slide down the bottom plate 29, being collected in the collecting tray 16. The boiled water continues through the heating channel system and runs down into the collecting container 17, from where it will again enter the recycling circuit.

In the collecting container the hot water causes a certain amount of evaporation. As a result of the collecting tray's 16 perforated bottom the surface of the ice cubes in the collecting tray 16 will be moist, with the result that the ice cubes do not become frozen to one another. The ice cubes gradually produce some melt water, which runs down into the collecting container 17 and enters the recycling process.

The purpose of the boiling process is both to loosen the ice cubes and to sterilise the water which is frozen into ice cubes. New water is supplied to the recycling circuit from the boiling element 6. After the boiling has been in progress for a certain period, the thermostat 25 registers a temperature increase in the bottom plate 29 and issues a signal to switch off the boiling process.

Fig. 1 illustrates that the recycling vessel 9 has two inlets, both from the collecting tray 15 and from the collecting container 17. The recycling vessel 9 will normally be full, which also applies to the tube from the collecting tray 15 to the recycling vessel 9. Thus it is the position of the collecting tray which determines the pressure in the recycling vessel 9. Since the collecting tray 15 is located higher than the collecting container 17, it will not be possible for water therefrom to be passed into the recycling vessel 9. On the other hand the non-return valve 8 ensures that water cannot flow into the collecting container 17 from the recycling vessel 9. During the operation of the ice cube machine, therefore, it is first and foremost from the collecting tray 15 that the recycling vessel 9 receives water. As the ice cubes are formed, the water in the recycling circuit disappears, and the higher pressure from the water in the collecting tray 15 is lost. Further supply to the recycling vessel 9 then comes from the collecting container 17.

After a period of operation the water in the storage tank 3 has been used up, but there is still a need for hot water to loosen the ice cubes. Like the collecting tray 15 the storage tank 3 is located higher than the collecting container 17, with the result that the pressure in the coupling 4 is greater than the pressure in the collecting container as long as there is water in the storage tank. When the water in the storage tank 3 has been used up, the pressure drops at the inlet of the boiling element, causing water to flow from the collecting container 17, through the non-return valves 18 and 5 and into the boiling element 6. The non-return valve 18 prevents water from flowing from the storage tank 3 into the collecting container 17.

When all the water in the ice cube machine has been used up, this is detected by a temperature sensor (not shown) connected to the boiling element 6, since the temperature of the boiling element 6 becomes too high as a result of the lack of supplied water. The process is stopped, and both the compressor 19, the pump 10 and the boiling element 6 are switched off automatically. During maintenance cooling of ice cubes in the collecting tray 16 the compressor will still be in operation. Lack of water in the recycling circuit for water leads to a rapid drop in temperature in the bottom plate 29. The temperature drop is registered by the thermostat, which switches on the boiling element 6, thus supplying water to the recycling circuit from the storage tank 3 via the heating channels 32 and the collecting container 17. Thus in theory it is not necessary to fill water in the collecting container 17 before first time start-up, but it should be done for practical reasons since the pump should not be allowed to run dry.

The actual formation of ice cubes is performed in the following manner: in the embodiment in figure 2 boiled water and steam flow in from the expansion container 27 through an inlet 39, through the heating channels 32, which are connected in series by means of connecting tube 40, and out through an outlet 41. In the embodiment in figure 3 boiled water and steam are distributed from the expansion manifold 27 to the channels in the partitions 35 and run out to the recycling system. The cooling medium flows in through an inlet 36, on through the evaporator tubes 30, which are connected in series by means of connecting tube 37, and out through an outlet 38. (In figure 2 only the top heating channel 32 and the top flow channel 30 for cooling medium are shown (broken line)).

The distributor tube 12 for the water which has to be frozen is provided at the upper edge 33 of the freezing element's bottom plate 29, thus causing the water to trickle down over the plate towards its lower edge 34. To prevent the water from running too quickly over the plate, its angle to the horizontal plane should not be too great. On the other hand a certain minimum angle is desirable in order for the ice cubes to slide down into the collecting tray after release. Tests have shown that the angle should be between 20° and 60°.

In order to ensure that the ice cubes do not remain lying in the channels 28, the latter are preferably designed with a width which increases slightly in the direction downwards from the bottom plate's upper edge 33 to its lower edge 34. This increase in width is achieved by a tapering of the partitions 35 in the direction down the plate.

Fig. 4 is a section along the line IV-IV in fig. 2 and illustrates an embodiment of the heating channels 32 and the evaporator tubes 30 for the cooling medium. In the illustrated embodiment the heating channels 32 and the evaporator tubes 30 are formed by connecting profiles with a curved cross section and flat flanges to the underside of the bottom plate 29, e.g. by soldering. Fig. 4 also shows an ice cube 42, formed on the bottom plate in the freezing zone 31, which is formed by an evaporator tube 30 for the cooling medium. The freezing zone 31 is not illustrated in more detail, since it is not exactly defined, but it may be considered as the area of the bottom plate which is located above the evaporator tube 30 and in the vicinity thereof at temperatures under 0°C.

The embodiment in figure 5 differs from that which is illustrated in figure 4 only in the lack of the heating channels 32. Use has been made instead of the channels of the partitions 35, as described in connection with figure 3.

In the production of ice cubes on the bottom plate 29, it is important to have good heat transport from the evaporator tubes 30 for cooling medium to the freezing zones 31 in the channels 28 in order that ice cubes should be formed as rapidly as possible without the freezing zones being expanded to include the zones between the tubes 30. In general, when deciding on materials and dimensions, a choice must be made in which, in addition to the material in the bottom plate and its thickness, the distance between the freezing zones, the distance from the freezing zones to the heating channels, the temperature in the guide tubes for cooling medium and the temperature in the heating channels must be taken into consideration.

In the invention the bottom plates 29 and the partitions 35 are preferably made of thin stainless steel, the typical thickness being 0.1 - 1.5 mm. This provides good heat transport across the plane of the plate, from the evaporator tubes 30 to the freezing zones 31, but poor heat transport in the plane of the plate, more specifically in the longitudinal direction of the freezing channels 28. Nevertheless, the heat transport from the heating channels via the plate to the freezing zone for release of the ice cubes will be adequate. Steel has sufficient mechanical strength to enable the thicknesses indicated to be realised. In the above the invention has been described with reference to special embodiments. It should be understood, however, that it will be possible to design a number of elements in the illustrated embodiment of the freezing element 14 differently without departing from the scope of protection according to the claims. The number of channels on the bottom plate, e.g., can be different if the ice cube machine has to be built into a refrigerator where the conditions with regard to space are different to those in a freestanding machine. It is also possible to design the heating and evaporator systems differently. Again this may be relevant, for example, when they are built into a refrigerator, where the freezing element has to be adapted to the refrigerator's cooling circuit. A solution may also be envisaged where the heating channels, the evaporator tubes and the partitions are moulded in a suitable material, such as plastic, and glued to the bottom plate.

The invention is not allied to the use of conventional electrical operating means. Designs may be envisaged operated by solar cells and/or accumulators or gas-operated, for example by means of absorption cooling. The heating channels and/or the channels in the partitions may also be replaced by electrical heating conductors. All such variants are intended to fall within the scope of the invention.

Claims

PATENT CLAIMS

1. A device for use in the production of ice cubes in a machine where water is distributed in a layer over a freezing plate (14) which is supplied with means for providing cold or heat, wherein there is provided on the freezing plate (14), in the bottom plate's longitudinal direction, at least one channel (28), which is defined in the lateral direction by preferably outwardly inclining walls (35) and wherein the bottom plate (29) is connected to at least one transverse evaporator tube (30) for through-flow of a cooling medium and establishment of a freezing zone on the bottom plate (29) in the area of the evaporator tube/tubes (30), characterized in that on the freezing plate (14) there are also provided heating means (32,25) across and/or parallel to the bottom plate's (29) longitudinal direction for releasing ice cubes which are formed.

2. A device according to claim 1, characterized in that the heating means are heating channels (32) provided on the underside of the freezing plate's (14) bottom plate (29) in a forward and backward-moving loop pattern, for through-flow of a heating medium, preferably hot air, hot water vapour or boiling water, and/or composed of the cavities in the partitions (35) between the channels (28) of the bottom plate (29).

3. A device according to claim 1 and/or 2, characterized in that the heating channels (32) and/or the evaporator tubes (30) for cooling medium are formed by connecting a plate or separate profiles with channel-shaped hollows to the bottom plate (29) by soldering, gluing or the like.

4. A device according to claim 1, characterized in that the partitions (35) between the walls are formed by mould pressing of the freezing plate's bottom plate (29).

5. A device according to claim 1, characterized in that the bottom plate (29) is inclined at an angle of between 20° and 60°, preferably between 27° and 33° in relation to the horizontal plane.

6. A device according to claim 1, characterized in that the bottom plate (29) has a width of several times the width of the desired ice cubes, and that the walls between the channels are triangular, with the point facing upwards.

7. A device according to claim 1, characterized in that the heating means are composed of electrical heating elements.