Patent Publication Number: US-10309706-B2

Title: Cooling or freezing device having an ice maker with a temperature sensor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a cooling or freezing device which is equipped with an ice maker. 
     2. Description of the Prior Art 
     In many households of private individuals there are nowadays refrigerators or freezing devices which contain an ice maker for producing ice pieces. Some of these devices have, for example on the front of a device door, a delivery mechanism via which the ice pieces produced by means of the ice maker can be delivered in a metered manner. 
     An important criterion in the case of ice makers is the ice production rate, that is to say the quantity of ice pieces (e.g. expressed in the measuring unit kilograms) that can be produced per given unit time. The greater the ice production rate, the greater the usefulness for a private household, especially on hot summer days. There is therefore the general desire in the case of ice makers for as high an ice production rate as possible. 
     In order to determine when the water introduced into an ice-making tray has frozen and the finished ice pieces can accordingly be ejected from the ice-making tray, conventional ice makers are usually equipped with a suitable sensor element (temperature sensor) which supplies a temperature measurement signal. On the basis of the temperature measured by means of the sensor element, a control unit decides when to eject the ice pieces from the ice-making tray. 
     In order to accelerate the freezing process, it is known in the case of ice makers to provide a cold air stream which flows along the ice-making tray. The flowing cold air has, for example, a temperature which is significantly below the freezing temperature of water (e.g. minus 20° C. or below) and, owing to the dissipation of heat energy released from the water, effects more rapid freezing of the water. 
     SUMMARY OF THE INVENTION 
     The present invention starts from a configuration in which a cold air stream flows along the underside of an ice-making tray of the ice maker, and a sensor element serving as a temperature sensor is arranged on the underside of the ice-making tray. It is an object of the present invention to avoid as far as possible a local impairment of the cooling effect of the cold air stream as a result of the presence of the temperature sensor. 
     In order to achieve that object there is provided according to the invention a cooling or freezing device comprising an ice-making tray having a plurality of ice-piece-producing cavities distributed over at least two rows of cavities running parallel to one another, a cold air supply system which provides a cold air stream which flows beneath the ice-making tray along the rows of cavities, and a temperature sensor unit which is inserted into a gap formed on the underside of the tray between a pair of adjacent ice-piece-producing cavities, characterised in that the pair of cavities is formed by two ice-piece-producing cavities which, as seen in the direction of flow of the cold air stream, are the last ice-piece-producing cavities of two adjacent rows of cavities. 
     In the solution according to the invention, the temperature sensor unit is inserted between two adjacent rows of ice-piece-producing cavities. It is thereby arranged between the last ice-piece-producing cavities—as seen in the direction of flow of the cold air stream—of the two rows of cavities in question. Although the temperature sensor unit constitutes an obstacle for the flowing cold air, the solution according to the invention ensures that at most only a very small portion of the outer surface of the ice-making tray on the underside thereof is screened from the cold air stream by the temperature sensor unit. The important factor for the ice production rate of the ice maker is not the time required until the first ice cubes in the ice-making tray have frozen but the required time until the last ice cube has frozen. In regions of the outer surface of the ice-making tray that are shielded from the cold air stream by the temperature sensor unit, a reduced cooling effect of the cold air stream and consequently a longer freezing time of the water are to be expected. If the temperature sensor unit were arranged between two ice-piece-producing cavities that belong to the same row of cavities and are arranged one behind the other in the direction of flow of the cold air channel, a reduced cooling effect on account of the shielding effect of the temperature sensor unit would have to be expected for all the ice-piece-producing cavities situated in the row in question behind the temperature sensor unit in the direction of flow. Likewise, in a case where the temperature sensor unit is arranged between two ice-piece-producing cavities that belong to adjacent rows of cavities but are not the last ice-piece-producing cavities in the two rows of cavities, it would have to be expected that, in both rows, the further cavities situated behind the two ice-piece-producing cavities are shielded to a certain degree by the temperature sensor unit. However, by choosing, according to the invention, two ice-piece-producing cavities that are arranged adjacently transversely to the direction of flow of the cold air stream and that are the last ice-piece-producing cavities, as seen in the direction of flow of the cold air stream, in their respective row of cavities, the regions of the underside of the ice-making tray that are affected by the mentioned shielding effect are reduced to a minimum. It has been shown that, with the measure according to the invention, a significant increase in the ice production rate can be achieved as compared with configurations in which the temperature sensor unit is arranged between a pair of cavities located in a different position in the ice-making tray. 
     In some embodiments, the temperature sensor unit comprises a temperature sensor element which is in direct contact with the cavity walls of the pair of cavities between which the temperature sensor unit is inserted. 
     In some embodiments, the cold air supply system comprises a cold air guide trough which is arranged beneath the ice-making tray, which trough delimits a cold air channel for guiding the cold air stream. 
     In some embodiments, the ice-making tray is longer than it is wide, the cold air stream flowing along the ice-making tray in the longitudinal direction thereof. However, configurations in which the cold air stream flows along the ice-making tray in the transverse direction thereof and the temperature sensor unit is inserted between the last ice-piece-producing cavities of two adjacent rows of cavities extending in the transverse direction of the tray are not ruled out within the scope of the present disclosure. 
     The invention will be explained further hereinbelow with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal section through the middle of an ice-making module according to one embodiment. 
         FIG. 2  is a perspective view of the ice-making module of  FIG. 1  from obliquely below. 
         FIG. 3  is a cross-section through the ice-making module of  FIG. 1 . 
         FIG. 4  is an enlarged section of the ice-making module of  FIG. 1  in the region of a temperature sensor unit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will first be made to  FIGS. 1 to 3 . The ice-making module shown therein is generally designated  10 . It is intended to be fitted into a cooling or freezing device for domestic use and serves to produce ice pieces. For this purpose, the ice-making module  10  comprises an ice-making tray  12  having an approximately rectangular tray outline. In the ice-making tray  12  there is formed a plurality of ice-piece-producing cavities  14 , each of which serves to produce a single ice piece. The ice-piece-producing cavities  14  are distributed over a plurality (in the example shown, two) of rows  14   a ,  14   b  of cavities  14 , which extend in the direction of the longer rectangle sides of the ice-making tray  12  and each contain a plurality (in the example shown, five) of ice-piece-producing cavities  14 . The direction of the longer rectangle sides of the ice-making tray  12  is referred to hereinbelow as the longitudinal tray direction, while the direction of the shorter rectangle sides of the ice-making tray  12  is referred to as the transverse tray direction. 
     The ice-making tray  12  is mounted on a module housing  16 , which surrounds it in the manner of a frame, so as to be rotatable about an axis of rotation  18  extending in the longitudinal tray direction. When the ice-making module  10  is in the fitted state in the cooling or freezing device, the axis of rotation  18  is horizontal. By rotation about the axis of rotation  18 , the ice-making tray  12  can be rotated between an ice-producing position shown in  FIGS. 1 to 3 , in which the tray plane of the ice-making tray  12  lies in a horizontal plane, and an ice-ejecting position, which is not shown in greater detail in the figures, in which the ice-making tray  12  has been rotated through a sufficiently large angle of rotation (for example at least 90 degrees or more) relative to the ice-producing position to allow the finished ice pieces to be ejected from the ice-making tray  12 . In the example shown, the ice-making module  10  works by the twist-tray principle, that is to say the ice-making tray  12  is twisted on itself in the region of its ice-ejecting position by being rotated further in the region of one of its longitudinal ends while being held in place in the region of its other longitudinal end. The resulting twisting of the ice-making tray  12  causes the ice pieces in the ice-piece-producing cavities  14  to break away from the cavity walls, which facilitates emptying of the ice-making tray  12 . When the ice-making module  10  is in the fitted state, there is a receiving container (not shown) of a suitable size beneath the ice-making tray  12 , in which the ice pieces that fall out of the ice-making tray  12  are received and collected. 
     For driving the ice-making tray  12  in rotation, a drive unit  20  is accommodated in the module housing  16 , which drive unit comprises a drive motor, for example an electric motor drive motor, which is in driving connection with the ice-making tray  12  via a reduction gear unit, which is not shown in detail. 
     The ice-making module  10  is fitted in the cooling or freezing device, for example, in such a manner that it is oriented with the axis of rotation  18  parallel to mutually opposite side walls of a wall system delimiting a cooling or freezing compartment of the cooling or freezing device. The cooling or freezing compartment can be closed at the front by a device door of the cooling or freezing apparatus, for example, and is delimited at the back by a rear wall. Parts of a cold air supply system which serves to produce a cold air stream and guide it to the ice-making tray  12  can be arranged behind the rear wall. In particular, at least parts of a guide system which guides the cold air that is produced from a cold air source into the region of the ice-making module  10  can be arranged behind the rear wall. 
     The cold air supply system  21  comprises as components that are structurally integrated into the ice-making module  10  a cold air guide trough  22  (omitted from  FIG. 2  for reasons of clarity) arranged beneath the ice-making tray  12  and also a mouthpiece  24  which forms an outlet opening  26  for the cold air. The mouthpiece  24  is part of the mentioned guide system, which delivers the cold air produced by the cold air source to the ice-making tray  12 . The cold air is blown through the mouthpiece  24  into a cold air channel  28  formed between the ice-making tray  12  and the cold air guide trough  22 . The cold air guide trough  22  is arranged with its longitudinal trough axis parallel to the longitudinal tray direction of the ice-making tray  12 . Accordingly, the cold air channel  28  runs beneath the ice-making tray  12  in the longitudinal tray direction from one longitudinal tray end to the opposite longitudinal tray end. The cold air flowing in the cold air channel  28  flows along the underside of the ice-making tray  12  in contact with the outer surface of the cavity walls of the ice-piece-producing cavities  14 . The direct contact of the flowing cold air with the material of the ice-making tray  12  results in efficient heat dissipation from the ice-making tray  12  by the cold air stream, which accelerates the freezing of water introduced into the ice-piece-producing cavities  14  to form ice pieces. 
     At the downstream end of the cold air channel  28 , that is to say at the end of channel remote from the mouthpiece  24 , the cold air emerges from the cold air channel  28  into the region surrounding the ice-making module  10 . It is of course conceivable in other embodiments purposively to collect the cold air in the region of the downstream end of the channel and to guide it back to a specific location in a defined manner. 
     Fixed to the underside of the ice-making tray  12  is a temperature sensor unit  30 , the measured signal of which is evaluated by a control unit, which is not shown in greater detail, in order to detect when the water introduced into the ice-piece-producing cavities  14  has frozen, so that the ice-making tray  12  can be emptied and refilled with fresh water. As is apparent especially from  FIGS. 1 and 2 , the temperature sensor unit  30  is inserted into a gap between the two ice-piece-producing cavities that are furthest downstream, which are here designated  14   1  and  14   2  for the purposes of better identification. The ice-piece-producing cavity  14   1  is the last cavity in the direction of flow of the cold air flowing in the cold air channel  28  of a first of the rows of cavities, and the ice-piece-producing cavity  14   2  is the last cavity in the direction of flow of the other of the two rows of cavities. This arrangement of the temperature sensor unit  30  results in a very low degree of shielding of ice-piece-producing cavities  14  from the cold air flowing in the cold air channel  28 : The cavities situated upstream of the ice-piece-producing cavities  14   1 ,  14   2  (in the example shown, a total of four per row of cavities) are largely unaffected by the shielding effect of the temperature sensor unit  30 . The two ice-piece-producing cavities  14   1 ,  14   2  are themselves shielded directly by the temperature sensor unit  30  at most in the regions of their cavity walls that face one another. In addition, there are no further cavities behind the ice-piece-producing cavities  14   1 ,  14   2  (that is to say downstream thereof). It has been shown that, with the arrangement of the temperature sensor unit  30  shown, a sufficiently good cooling effect of the cold air stream in the cold air channel  28  can be achieved over all the ice-piece-producing cavities  14 . 
     Reference will now be made in addition to  FIG. 4 . The temperature sensor unit  30  comprises a temperature sensor  32  formed, for example, by an electrical resistor element with a negative temperature coefficient (NTC element), which in the example shown has a rod-like main sensor portion  34  which is in direct contact with the cavity walls of the two ice-piece-producing cavities  14   1 ,  14   2 . The temperature detected by the temperature sensor  32  is a measure of the temperature of the water in the two ice-piece-producing cavities  14   1 ,  14   2 . The temperature sensor  32  is accommodated in a sensor housing  36 , which is fixed to the underside of the ice-making tray  12  by, for example, a snap connection or another type of fixing. The remaining space inside the sensor housing  36  is filled with a thermally insulating material  38 , which is indicated schematically in  FIG. 1  by a plurality of circles coloured black and is omitted from  FIG. 4  for reasons of clarity. The insulating material  38  insulates the temperature sensor  32  thermally with respect to the cold of the cold air flowing in the cold air channel  38 , which has a temperature of, for example, minus 20° C. or below. As can readily be seen in  FIG. 4  especially, the temperature sensor unit  30 —when seen in a tray cross-section—fills the gap between the two ice-piece-producing cavities  14   1 ,  14   2  substantially completely. When seen in cross-section, that gap has approximately the outline of a triangle. The sensor housing  36  extends substantially into the region of the cavity bottom of the ice-piece-producing cavities  14   1 ,  14   2 , but in other embodiments it may of course end before the cavity bottom of the two cavities or even project beyond the cavity bottom of the two cavities. 
     Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.