Patent Publication Number: US-11045018-B2

Title: Display unit for storing and displaying heated goods, and use of a display unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application (under 35 USC § 371) of PCT/NL2017/050423, filed Jun. 25, 2017, which claims benefit of Netherlands application No. 2017055, filed Jun. 27, 2016, the contents of each of which are incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a display unit used to present heated goods in shops, snack bars, gas pump stations, fast food restaurants, cafeterias, and the like. An air forcing apparatus, such as a fan, and an air heater, such as a heating element, are provided in order to keep the goods hot. 
     A display unit of this type is known from WO-2010/002243-A2. The display unit of WO-2010/002243-A2 comprises walls, multiple shelves, an air duct, a fan and an air heater. The walls delimit one chamber with an open front side. The multiple shelves each comprise an upper placing side, and are provided above each other to define an individual storage space above each shelf. The air duct extends from an inlet opening to multiple outlets whereby the outlets each define a flow direction. The flow directions of the multiple outlets point away from the corresponding placing sides. 
     A disadvantage of the known display unit is that its use is limited in terms of placement options. In particular, the known display unit is best placed against a wall, while other positions in a room are less desirable. 
     The invention aims to solve to this problem, or at least to provide an alternative. In particular, the invention aims to provide a display unit that allows users to reach for the goods from at least two sides of the display unit, while ensuring an effective and efficient temperature control of the stored goods. 
     SUMMARY OF THE INVENTION 
     A display unit for storing and displaying heated goods comprises multiple walls, multiple shelves, an air duct, an air forcing apparatus, and an air heater. At least part of the walls of the display unit delimit a main chamber including a first open front side and a second open front side opposite of the first open front side. The multiple shelves each comprise an upper placing side. The multiple shelves each extend in the main chamber and define an individual corresponding storage space above their upper placing side. The air duct extends from at least a first inlet to multiple outlets which are in communication with the storage spaces. The display unit further comprises a transparent wall, which is positioned in the main chamber between the first open front side and the second open front side, and divides the main chamber in a first chamber and a second chamber. 
     Within the context of the invention, open front sides are openings connecting the main chamber with an environment in which the display unit is placed. Thanks to the two open front sides, users can see and reach for the goods that are in the main chamber of the display unit from two sides. This allows for placement of the display unit in an island position, and not just against a wall. Moreover, considering that the depth of a display unit is limited from a user point of view, having two open front sides enables a larger display unit and thus more storage capacity. The transparent wall ensures that the airflow within the first and second chamber is not adversely affected by the airflow in the other chamber, or by draught which might otherwise run through the main chamber from the first open front side to the second open front side, or reversely. 
     In an embodiment, the transparent wall is made of glass. Glass is heat resistant, has good transparency, and is readily cleaned. 
     In an embodiment, the transparent wall is positioned halfway the main chamber. This provides first and second chambers of equal size, which is practical from a use point of view. 
     In an embodiment, the air duct comprises a first vertically extending outlet duct for guiding air towards the outlets. In particular the first vertically extending outlet duct is positioned at a side edge of the transparent wall. This allows the transparent wall to be in the center, which enhances the impression of one uninterrupted chamber. 
     In particular, the air duct comprises a second vertically extending outlet duct for guiding air towards the outlets. In particular the second vertically extending outlet duct is positioned at a side edge of the transparent wall opposite of the first vertically extending outlet duct. By having two outlet ducts, the outgoing air flow is divided over two, and can be transported in a more equal manner towards the outlets. Moreover, each individual outlet duct can be smaller, thus less obstructing the main chamber. By having both ducts opposite of each other, a symmetry is achieved, and the impression of one uninterrupted chamber is enhanced even further. 
     In an embodiment, the air duct comprises a first vertically extending inlet duct for guiding air from the first inlet. In particular the first vertically extending inlet duct is positioned at a side edge of the transparent wall. This allows the transparent wall to be in the center, which enhances the impression of one uninterrupted chamber. In a particular embodiment, the first vertically extending outlet duct, and the first vertically extending inlet duct, are both at a side edge of the transparent wall, which allows for integration of both ducts and further improves the impression of one uninterrupted chamber. 
     In particular, the air duct comprises a second vertically extending inlet duct for guiding air from a second inlet. More in particular, the second vertically extending inlet duct is positioned at a side edge of the transparent wall opposite of the first vertically extending inlet duct. By having two inlets and inlet ducts, the outlet air flow is taken in from two points, resulting in a better airflow towards the inlets. Moreover, each individual duct can be smaller, thus less obstructing the main chamber. By having both ducts opposite of each other, a symmetry is achieved, and the impression of one uninterrupted chamber is enhanced even further. 
     In an embodiment, the first inlet, and optional second inlet are provided in the main chamber, in particular an upper region of the main chamber. By drawing air from the main chamber, air is at least partly recirculated and requires less conditioning compared to taking air from outside the display unit. Providing the inlets in the upper region is particularly advantageous in combination with the circulation of hot air, as it flows upwards naturally. 
     In an embodiment, at least part of the outlets, in particular all outlets, are positioned at a front edge of one of the shelves. In particular, at least part of the outlets, in particular all outlets, are positioned at a front edge of all shelves. In particular at least part of the outlets, or all outlets, are directed upwards and towards the transparent wall for directing an airflow into the corresponding storage space. Providing the outlets at a front edge of the shelf allows for creating an air curtain in front of the relevant storage space. Having the outlets directed upwards and towards the transparent wall, results in both an air curtain and a circulation of hot air in the storage space, for conditioning of the goods. 
     In an embodiment, all outlets discharge into the storage spaces. This results in a maximum heat transfer between the hot air, and the goods. 
     In an embodiment, at least one of the shelves is hollow and defines part of the air duct. This is not only efficient from a material point of use, but also allows for heat transfer between the air in the hollow shelf and the goods on top of the shelf. 
     In an embodiment, the upper placing side of at least one of the shelves is airtight. This prevents air from flowing directly from the air duct to the goods on the shelf, which may deteriorate their quality. 
     In an embodiment, the air heater comprises at least one heating element, in particular an electrical heating element. 
     In an embodiment, the at least one heating element is provided in one of the multiple shelves. This is both efficient in terms from a construction point of view, as the heating elements do not need to be placed elsewhere in the construction, where a heating element might require extra space as it is from an energy efficiency point of view because the heat is applied in the area where the goods need to be conditioned. Moreover, this position allows for an extra heat transfer in the form of radiation heat from the heating elements, via the shelf, to the goods. 
     In an embodiment, the air heater comprises multiple heating elements, and each of the multiple shelves is provided with one heating element, in particular a flat shaped heating element. 
     In an embodiment, the air heater comprises multiple heating elements, and all shelves are provided with multiple heating elements. 
     In an embodiment, at least one shelf comprises a pressure chamber. The pressure chamber is part of the air duct. The pressure chamber(s) comprises multiple openings, connecting the pressure chamber with a hollow space of the respective shelf. The pressure chamber provides for a uniform air flow through the hollow space of the respective shelf. In particular, the pressure chamber has an elongated rectangular shape. In particular, the pressure chamber is provided in the hollow space of the respective shelf. In particular, the pressure chamber extends along the width direction of each shelf. In particular, the pressure chamber is in communication with the first and optional second vertically extending outlet duct. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention, its effects, and advantages will be explained in more detail on the basis of a schematic drawing, in which: 
         FIG. 1  shows a perspective view of a first embodiment of a display unit according to the invention; 
         FIG. 2  shows a cross section view through the display unit of  FIG. 1 ; 
         FIG. 3  shows a top section view through the display unit of  FIG. 1 ; 
         FIG. 4  shows a partial longitudinal section view through the display unit of  FIG. 1 ; 
         FIG. 5  shows the view of  FIG. 2  of the display unit in use; 
         FIG. 6  shows a top section view through the display unit of  FIG. 1  in use; 
         FIG. 7  shows another top section view through the display unit of  FIG. 1  in use; and 
         FIG. 8  shows a cross section view through a second embodiment of a display unit according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-7  show a first embodiment of a display unit for storing and displaying heated goods according to the invention, which is denoted in its entirety by reference number  1 . The display unit  1  comprises a top wall  2 , side walls  4 ,  6 , and bottom wall  8 . In this embodiment, the side walls  4 ,  6  are made of glass, while the top 2 and bottom wall  8  are made of metal. The display unit  1  further comprises a support structure, which is not shown in the figures as any conventional support structure can be used within the scope of the invention. 
     The display unit  1  of this embodiment further comprises four shelves  10 ,  12 ,  14 ,  16 , two air ducts  18 , and an air forcing apparatus, in this embodiment two fans  20 ,  22 , as is shown schematically in  FIG. 1 . The two fans  20 ,  22  are positioned in the support structure. The two fans  20 ,  22  are provided within the air ducts  18 , and the air ducts  18  in the support structure are closed, i.e. are not provided with other inlets or outlets than those described below. 
     The display unit  1  further comprises an air heater. In this embodiment, the air heater comprises multiple electrical heating elements  24 , and all shelves  10 ,  12 ,  14 ,  16  are provided with electrical heating elements  24 , as shown in  FIG. 2 . 
     The top wall  2 , side walls  4 ,  6 , and bottom wall  8  delimit a main chamber  26 . The main chamber  26  has a first open front side  28  and a second open front side  30  opposite of the first open front side  28 . The multiple shelves  10 ,  12 ,  14 ,  16  each comprise an upper placing side  32  on which goods can be placed. 
     Each air duct  18  extends from a first inlet  42 , or from a second inlet  44 , to multiple outlets  46  which are in communication with the storage spaces  34 ,  36 ,  38 ,  40 . The first and second inlets  42 ,  44  are provided in an upper region of the main chamber  26 , as is shown in more detail in  FIG. 7 . Each outlet  46  is a slotted-shaped opening that extends as one opening over substantially the entire width of each shelf  10 ,  12 ,  14 ,  16 . 
     The display unit  1  further comprises two vertically extending transparent walls  48 ,  50  made of glass, which are positioned above each other in the main chamber  26  halfway between the first open front side  28  and the second open front side  30 . The transparent walls  48 ,  50  divide the main chamber  26  into a first chamber  52  and a second chamber  54 . The multiple shelves  10 ,  12 ,  14 ,  16  each extend in the main chamber  26 . In this embodiment, half of the multiple shelves, shelves  10  and  12 , are provided above each other in the first chamber  52  to define individual corresponding storage spaces  34 ,  36  above their upper placing side  32 . The other half of the multiple shelves, shelves  14  and  16 , are provided above each other in the second chamber  54  to define individual corresponding storage spaces  38 ,  40  above their upper placing side  32 . The lower transparent wall  48  extends vertically from the bottom wall  8  to the upper shelves  12 ,  16 . The upper transparent wall  50  extends vertically from the upper shelves  12 ,  16  to the top wall  2 . 
     The lower and upper borders of the first open front side  28  and the second open front side  30  are delimited by rectangular transparent sheets, in this embodiment rectangular glass sheets  56 . The glass sheets  56  make the first open front side  28  and the second open front side  30  physically slightly smaller, without visually decreasing the size of the first open front side  28  and the second open front side  30 . The lower glass sheets  56  are located adjacent the outlets  46  of the lower shelves  10 ,  14 . They prevent, or at least decrease the amount of, cool air being drawn into the respective storage space  34 ,  38  by the relative high velocity of air exiting the outlets  46 . The upper glass sheets  56  prevent, or at least decrease the amount of, cool air entering the upper side of the upper storage spaces  36 ,  40 , and help the warmer air stay within the upper storage spaces  36 ,  40  (see also  FIG. 5 ). 
     Referring to  FIG. 3 , the air ducts  18  comprises a first vertically extending outlet duct  58  and a second vertically extending outlet duct  60  for guiding air from the fans  20 ,  22  towards the outlets  46 . The first vertically extending outlet duct  58  and the second vertically extending outlet duct  60  are positioned at side edges of the transparent walls  48 ,  50 , opposite of each other. The air ducts  18  further comprise a first vertically extending inlet duct  62  and a second vertically extending inlet duct  64  for guiding air from the first inlet  42 , respectively from the second inlet  44 , towards the fans  20 ,  22 . The first and second vertically extending inlet ducts  62 ,  64  are positioned at side edges of the transparent wall  48 ,  50  opposite of each other. In this embodiment, the first vertically extending outlet duct  58  is integrated with the first vertically extending inlet duct  62 . Likewise, the second vertically extending outlet duct  60  is integrated with the second vertically extending inlet duct  64 . Seen from the outside, as shown in  FIG. 1 , the integrated outlet and inlet ducts appear as two vertically extending columns, which together with the top and bottom walls  2 ,  8  form a frame for the transparent walls  48 ,  50 , and support the multiple shelves  10 ,  16 . The integrated inlet and outlet ducts together with the transparent walls  48 ,  50  separate the first chamber  52  and the second chamber  54  in a substantially airtight manner. Substantially airtight means within the scope of the invention that there might be some clearance between the integrated inlet and outlet ducts together with the transparent walls  48 ,  50  for practical purposes, such as cleaning, and constructional purposes, such as allowance for thermal expansion. However, this clearance is so small that any air exchange between the first and second chambers  52 ,  54  is negligible compared to the main air flows as described below. In particular, any air exchange between the first and second chambers  52 ,  54  is less than 5%, in particular less than 1%, of the joint air flow through the ducts  18 . 
       FIG. 4  shows that the multiple shelves  10 ,  12 ,  14 ,  16  are hollow, and that the first vertically extending outlet duct  60  and the shelves  10 ,  12  are provided with corresponding openings  66 . In this embodiment, but not shown in the figures, there are similar openings connecting the second vertically extending outlet duct  62 , with the shelves  10 ,  12 , connecting the first vertically extending outlet duct  60  with the shelves  14 ,  16 , and connecting the second vertically extending outlet duct  62 , with the shelves  14 ,  16 . The openings  66  allow air to flow from the respective outlet duct  60 ,  62  into the respective communicating hollow shelves  10 ,  12 ,  14 ,  16 , and onwards to the outlet openings  46 . 
     In this embodiment, all outlets  46  are positioned at a front edge of the multiple shelves  10 ,  12 ,  14 ,  16 . Moreover, all outlets  46 , are directed upwards, i.e. away from the placing sides  32 , and towards the transparent wall  48 ,  50  for directing an airflow into the corresponding storage space  34 ,  36 ,  38 ,  40 . The upper placing side  32  of all shelves  10 ,  12 ,  14 ,  16  of this embodiment are airtight. Moreover, the first and second vertically extending outlet ducts  58 ,  60 , as well as the first and second vertically extending inlet ducts  62 ,  64 , of this embodiment are airtight too, except for the inlets  42 ,  44 , the outlets  46 , and the openings  66 . As a result, the air ducts  18  discharge air only via the outlets  46  into the storage spaces  34 ,  36 ,  38 ,  40 . 
       FIG. 8  shows a second embodiment of a display unit  101  according to the invention. The same or similar elements as in the first embodiment are denoted with the same reference numbers, and are not explained in detail. 
     Each shelf  10 ,  12 ,  14 ,  16  of the display unit  101  further comprises a pressure chamber  68 . The pressure chamber  68  has an elongated rectangular shape, is provided in the hollow space of the respective shelf  10 ,  12 ,  14 ,  16 , and extends along the width direction of each shelf  10 ,  12 ,  14 ,  16 . The pressure chamber  68  is in communication with the first and second vertically extending outlet ducts  60 ,  62  via the openings  66 . Each pressure chamber  68  comprises a row of further openings (not shown in  FIG. 8 ), connecting each pressure chamber  68  with the rest of the hollow space of the respective shelf  10 ,  12 ,  14 ,  16 . The pressure chambers  68  provide for a uniform air flow through the hollow space of the respective shelf  10 ,  12 ,  14 ,  16 . 
     The display unit  101  of this embodiment comprises an air heater, comprising multiple flat shaped electrical heating elements  124 . Each shelf  10 ,  12 ,  14 ,  16  is provided with one flat shaped electrical heating elements  124 . 
     In practice, a display unit according to the invention, such as one of the display units  1 ,  101  described above, is used for presenting heated goods to potential buyers. These goods are placed on the placing sides  32  of the multiple shelves  10 ,  12 ,  14 ,  16 . The fans  20 ,  22  draw air from the upper region of the first, respectively second chamber  52 ,  54  via the inlets  42 ,  44 , as shown with dotted arrows in  FIG. 7 , and with the dot/hyphen arrows in  FIG. 5 . The air is transport downwards through the first and second vertically extending inlet ducts  62 ,  64  to the fans  20 ,  22 , and forced upwards through the first and second vertically extending outlet ducts  58 ,  60 , as shown schematically with dotted arrows in  FIG. 5 . Note that the placement of the arrows in  FIG. 5  appears to suggest that incoming, downwards air flow to the fans  20 ,  22  and the outgoing air flow are located left and right of each other (in the orientation of  FIG. 5 ), with the transparent walls  48 ,  50  separating these. However, the actual outlet ducts  58 ,  60  and inlet ducts  62 ,  64  are located in front of each other (in the orientation of  FIG. 5 ), as can be seen clearly in the top sectional views of  FIGS. 3, 6, and 7 . Accordingly, the ingoing and outgoing air flows are in front of each other as well, seen in the orientation of  FIG. 5 . 
     The air flow enters the hollow shelves  10 ,  12 ,  14 ,  16  through the openings  66 . In the embodiment of  FIG. 8 , the air flow enters the pressure chamber  68  via the openings  66  first, and then enters the rest of the respective hollow shelf  10 ,  12 ,  14 ,  16 . Subsequently, the air flow is heated by the electrical heating elements  24  (see  FIGS. 4 and 6 ), or the flat shaped heating element  124  ( FIG. 8 ). The heated air and the radiation from the electrical heating elements  24 ,  124 , warm the goods in the storage spaces  34 ,  36 ,  38 ,  40  from below through the placing sides  32 . The heated air then exits the air duct  18  via the outlets  46  (see  FIG. 5 ). The outlets  46  direct the heated air upwards and backwards into the storage spaces  34 ,  36 ,  38 ,  40 . The air flow deflects against the ceiling of the respective storage space  34 ,  36 ,  38 ,  40 , either the bottom side of another shelf  12 ,  16 , or the bottom side of the top wall  2 , and is directed down by the glass walls  48 ,  50 . At the bottom of the glass walls  48 ,  50  the air flow continues over the placing side  32  of the respective shelf  10 ,  12 ,  14 ,  16 , where it warms the goods on the placing sides  32  from above. The air flow then continues upwards. The upward air flow from the lower storage spaces  34 ,  48  then at least partly enters the upper storage spaces  36 ,  40 , because it is drawn in by the relative high velocity of the air flow coming out of the outlets  46  of the upper shelves  12 ,  16 . The upward air flow from the upper storage spaces  36 ,  40  is drawn into the outlets  42 ,  44 . 
     It is important for the heating of the goods on the placing sides  32 , that the air flow as described is relative constant and not too much disturbed by influences from outside. The glass walls  48 ,  50  ensure that the air flows in adjacent storage spaces  34 ,  36 ,  38 ,  40  do not influence each other. Moreover, the glass walls  48 ,  50  prevent the occurrence of a draught through the storage spaces  34 ,  36 ,  38 ,  40  from one open front side  28 ,  30  to another. Because the glass walls  48 ,  50  are transparent, the lower storage spaces  34 ,  38  appear to be one space, the upper storage spaces  36 ,  40  appear to be one space too, and users have an overview over all goods from both open front sides  28 ,  30 . 
     Several variants are possible within the scope of the attached claims. The features of the above described preferred embodiments may be replaced by any other feature within the scope of the attached claims, such as the features described in the other of the two preferred embodiments, or in the following paragraphs. Accordingly, an embodiment of the invention has a pressure chamber in each shelf and multiple heating elements in the shelves. In another embodiment, the shelves do not have a pressure chamber, and each shelf has one flat shaped electrical heating element. 
     In an embodiment, the transparent wall, or walls, and/or the rectangular transparent sheets in front of the storages spaces are made of transparent plastic, such as Perspex™. 
     Two air ducts are advantageous in terms of air flow. However, another embodiment of the invention has one air duct, e.g. an air duct at one side of the transparent wall, or walls. In another embodiment, the air ducts are integrated within the side walls of the display unit. 
     In an embodiment, further outlets are provided, in particular one outlet at the lower side of each open front side of the display unit that provides an air curtain in front of the shelves and/or multiple small outlets in the upper and/or lower sides of the shelves. 
     Advantageously, the outlets are formed by a slotted-shaped opening that extends as one opening over substantially the entire width of each shelf, as in the above described embodiment. A comparable effect can be achieved through a series of outlets that extend substantially along a line parallel to the front edge of the shelf. The outlet can also be provided directly in the top side of the shelf in which the required outlet is achieved in an upwards and to the rear direction of the flowing hot air through partitions and/or fins. In the illustrated embodiment shown above, the outlets are provided along the farthest away front edge of the shelf. It is also possible that the outlets extend at a distance from and parallel to the front edge of the shelf, in which part of the shelf extends in front of the outlet. This part that extends in front of the outlet is small relative to the depth of the shelf and is not a part of the shelf that is used to place food on. The part of the shelf that is used to place food on is referred to as the placing part. 
     Generally, the flow direction of the outlets creates an angle of between 5 and 80 degrees with a plane in which the placing side of the shelf extends. Particularly, this angle amounts to between 15 and 65 degrees and, even more particularly, between 30 and 45 degrees. Preferably there are only outlets on the top side of the shelves as illustrated in the embodiment above. There are no outlets in the rear, top and side walls of the display unit and in the bottom side of the shelves. This can provide different advantages. For example, this can provide a simpler construction, fewer air ducts would suffice and a smaller quantity of air can be circulated. 
     In an embodiment, further inlets are provided and/or placed at other positions. Inlets may be provided more to the front of the storage spaces, and/or in the upper area of the lower storage spaces, and/or or in a lower area of the storage spaces in order to suck out relative cold air. 
     In an embodiment, the air forcing apparatus is an air pump. In an alternative, an air flow can be provided and the air circulation can also be realised in a natural manner by using the density differences between hot and cold air. In such an embodiment, the air heater also acts as an air forcing apparatus. Preferably the inlet opening will then be provided at a lower level than the outlets. 
     In an embodiment, the air heater is a condenser of a heat pump. In particular, the evaporator of the heat pump cools a refrigerator, freezer, or display unit for cooled goods that is located in the vicinity of, or even integrated with, the display unit according to the invention. In another embodiment, the air heater is a burner for gas or liquid fuel. In an embodiment, the air heater is placed elsewhere in the air duct, e.g. in the part of the air duct that is in a lower support structure of the display unit. In an embodiment, the air heater extends around the air duct. 
     In an embodiment, the multiple shelves are fixed permanently, or semi-permanently, to the side walls and/or air duct. In another embodiment, the multiple shelves are removably attached, which is advantageous for cleaning purposes. The number of shelves may be less than four, e.g. two, or more than four, e.g. six, eight, ten, or even more. An even number is advantageous, as it enables a symmetric placement of shelves in the first and second chamber. The shelves extend substantially horizontally. Substantially horizontally means that the placing side of the shelf extends in such a plane that goods can be placed on this placing side without them falling off. Partitions or other means may have been provided within this context on the placing side of the shelf that contributes towards the goods remaining on the placing side. The placing side of the shelf creates an angle of less than 45 degrees with a horizontal face, which is considered to be substantially horizontal for the present invention. In particular, the placing side of the shelf creates an angle of less than 35 degrees with a horizontal face. The shelves preferably comprise a closed area to impede the exchange of air between two storage spaces that are on top of the other. Due to the air curtains according to the invention, the front side of the display unit can remain open during use. To save on energy, the open front side can also be provided with a door to close the open front side temporarily or semi permanently.