Patent Application
20100186421
The invention relates to an ice cube preparer as claimed in the preamble to claim 1, and to a method for operating the ice cube preparer as claimed in the preamble to claim 15.
Refrigerating appliances equipped with an automatic ice cube maker have become well known. These ice cube makers usually have a compartment, separated from the refrigeration compartment, in which a temperature below the freezing point of water obtains. This compartment contains an ice dish which can be filled with water. The water is either taken from a container, or the refrigeration device has a plumbed-in water supply so that the inflow of water to the ice dish can be controlled e.g. using a solenoid valve.
After a predetermined time, which is selected such that the water introduced will have passed into the frozen state under normal circumstances, the ice dish is automatically emptied into an ice cube container. Normally, a plurality of such ice-making operations are performed one after another until the ice cube container is completely filled.
It has now been found that, depending on the water quality and the cleanness of the air, there are not always sufficient crystallization nuclei present in order to initiate the crystallization process in the cooled water. As a result, water is still present and no ice has formed in the ice dish by the end of the normal freezing time. Although this water is at a temperature below the freezing point of water, the crystallization process has not yet started.
If the ice dish is emptied into the ice cube container in this state, the ice cube container will be filled with water instead of ice. This decanting tends to give the water the missing crystallization momentum and it passes instantly into the frozen state. The resulting ice is in this case a rather large shapeless lump in the ice cube container, which does not correspond to the desired result. The outcome is even less satisfactory if a number of ice making operations have already been performed and the ice cube container is already well filled with ice cubes. In this case, if the supercooled water is poured from the ice dish onto the already produced ice cubes in the ice cube container, a large lump of ice is produced which contains both the previously produced ice cubes and the ice resulting from the water that has been introduced. In this way, not only the result of the last ice making operation but also of the previous and already completed ice making operations will be undone.
In order to avoid such problems, seeding is often carried out in other applications. However, such a seeding device would be too expensive to be incorporated in a domestic refrigerator, for example. Another solution is to give the supercooled water more time to start the crystallization process by itself However, this significantly reduces the productivity of the ice cube maker.
The object of the invention is therefore to design an ice cube maker and a method for producing ice in a cooled compartment such that the water is virtually guaranteed to pass into the crystalline state as soon as it has fallen below its freezing temperature.
This object is achieved according to the invention by an ice cube maker having the features set forth in claim 1 and a method for producing ice having the features set forth in claim 15.
Water molecules have a dipole characteristic. This means that water molecule orientation can be influenced by applying a field. Through the application of a field to at least some of the water, a torque is exerted on at least this portion of the water molecules and the molecules are given angular momentum. It has now been shown that this momentum produces a similar effect to using a seed crystal, for example. The momentum is sufficient to initiate the crystallization process in water that has already fallen below its freezing temperature.
Advantageously, an electric field is generated in order to trigger the crystallization process. An electric field requires minimal equipment cost/complexity and can be easily produced in the strength necessary to exert the appropriate torque on the water molecules.
As the orientation of the water molecules shows the desired effect only if the water has already been cooled down accordingly, the electric field is not generated until the crystallization temperature of the water has been reached. Self-evidently, the electric field could also be applied in advance and turned off again once the crystallization temperature is attained. In this case, however, energy that is not necessary for achieving the desired effect would go to waste.
To initiate crystallization, it is not necessary for the water molecules to possess a particular orientation. It is merely important that the dipoles are given angular momentum. Consequently, it is not the absolute orientation of the water molecules but the relative change in the orientation that is critical for initiating the crystallization process. The electric field is therefore only applied for a short period of time.
To carry out the method in an ice cube maker, there are inventively provided two poles between which a field can be generated and which are disposed such that at least some of the water is in this field. As soon as crystallization has started even at one location, it will very quickly spread through the entire volume of water in the ice dish if this water has already reached the necessary low temperature. It is unnecessary for the entire volume of water to be in the field between the poles.
The poles are advantageously connected to a voltage source. This can be a separate voltage source, but it is also possible to utilize the voltage source used e.g. to power the ice cube maker.
One pole is advantageously constituted by the ice dish itself. As such ice dishes are often made of a conductive material, only the ice dish needs to be in electrical contact.
The other pole is inventively constituted by a pin which is electrically isolated from the ice dish and whose tip is surrounded by water when the ice dish is filled up. In addition, one of the poles must be isolated from the water, as otherwise an appropriate electric field will not be built up, but a current will flow through the water and electrolysis will take place. This isolation can be achieved by coating the ice dish with an insulating paint, for example.
Such ice dishes usually have a number of ice cube compartments so that the desired ice cubes are produced when the water crystallizes. To ensure that, once initiated, the crystallization process can propagate through all the ice cube compartments of the ice dish, the ice cube compartments are interconnected such that water can be exchanged between the ice cube compartments. Crystallization spreads throughout the ice dish through these connection points.
As the pin is surrounded by water in the filled ice dish, it will be inside an ice cube when the crystallization process is complete. This could cause problems when “harvesting” the ice cubes. To prevent this, the pin can advantageously be heated. In addition, it runs parallel to the removal direction of the ice cubes.
Particularly advantageously, the pin is conical in shape. This conicity additionally facilitates the harvesting of the ice cubes. On the other hand, the conicity also increases the field strength, as a very big charge is produced at the tip of the pin.
In another exemplary embodiment, the poles are implemented as capacitor plates. In this example, there are no problems with harvesting the ice cubes, as the capacitor plates do not need to be inside the ice cubes produced.
Particularly advantageously, the capacitor plates are disposed in the side walls of the ice dish and are isolated from the water. Thus, for example, two opposite side walls of the ice dish can be made of metal and provided with appropriate electrical contacts and electrically isolated from one another. The isolation from the introduced water can again be provided by applying a coat of insulating paint.
Although the ice cube maker according to the invention can be implemented as an independent unit, it can also be advantageously incorporated in a refrigerator.
Further details and advantages of the invention will emerge from the sub-claims in conjunction with the description of an exemplary embodiment which will be explained in detail with reference to the accompanying drawings in which:
The ice dish 1 shown in
The ice dish 1 with its base 6 and the frame 2 is advantageously made of aluminum in one piece. The internal partitions 4 can likewise be made from a single piece, but can also consist of some other material. It is likewise possible for the entire ice dish 1 comprising base 6, frame 2 and the internal partitions 4 to be manufactured from one material in a single piece.
In one of the ice cube compartments 3, an electrically conducting pin 7 is anchored in the base 6 (see also
The pin 7 is connected to a voltage source 5 via the terminal pin 10 and the frame 2, it being irrelevant whether a DC or AC voltage source 5 is used. In both cases, an electric field can be created in this way between the pin 7 and the frame 2.
In order to be able to release the pin 7 easily from the finished ice cube, a heating resistor can also be provided in the pin 7. However, to supply it with power, the pin 7 would have to be fitted with additional connection means. The heating of the pin 7 together with its conical shape enables the ice cube to be easily detached from the pin.
To prevent current from flowing through the water, the ice dish 1 is coated with an insulating paint. The insulating coating is applied to both the inside and the outside of the ice dish 1, thereby enabling dip coating to be performed.
According to the inventive method, the water introduced to the ice dish 1 is cooled down and thus attains the freezing temperature of the water. If sufficient crystallization nuclei are present, freezing commences. Otherwise, the water cools down even more and reaches a temperature which is below the freezing point. An electric field is now established between the pin 7 and the frame 2 of the ice dish 1 via the voltage source 5. In the field now present, the water molecules are oriented accordingly. The angular momentum thereby imparted to the water molecules initiates crystallization. Via the notches 8, crystallization can spread through the entire volume of water in the ice dish 1.
This ensures that water is not fed into the ice cube container (not shown here) of an ice cube maker. It also prevents ice cubes already produced from clumping together. In this way it is guaranteed that, after each ice cube production cycle, actually finished ice cubes are also emptied into the ice cube container.
It is also possible for an electric field to be created between two opposite side walls of the frame 2. In order to isolate these side walls from one another, a plastic frame could be provided into which the side sections that are to form the capacitor plates are inserted. These plate side sections then still have to be provided with electrical contacts and connected to the voltage source.
An insulating paint is also used in the exemplary embodiment not shown here. The two electrically conducting side walls between which the field is set up are coated with said paint.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 044 233.7 | Sep 2007 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2008/061692 | 9/4/2008 | WO | 00 | 3/8/2010 |
