Abstract:
The invention relates to a reefer container for shipping goods placed on pallets, which container comprises a plurality of sidewalls forming the sides, floor and ceiling in the container, a front end comprising cooling and or ventilating means and a rear end comprising an opening to be closed by one or more doors, a reefer machine further comprising one or more evaporators and one or more fans for transporting cooling air into the container, an evaporator ( 3 ) is placed above a fan ( 2 ) in an air circulating system for cooling the air ( 4 ) in the container ( 14 ), where air circulating or passing through the reefer machine ( 1 ) and guided from the evaporator ( 3 ) is divided into ducts ( 8 ) at both sides of the container ( 14 ). The invention further relates to a method of loading a reefer container ( 14 ) with pallets ( 15, 16 ).

Description:
[0001]    The invention relates to a reefer container for shipping goods placed on pallets, which container comprises:
       a plurality of sidewalls forming the sides, floor and ceiling in the container;   a front end comprising cooling and or ventilating means and a rear end comprising an opening to be closed by one or more doors;   a reefer machine further comprising one or more evaporators and one or more fans for transporting cooling air into the container;   that an evaporator is placed above a fan in an air circulating system for cooling the air in the container;   that air circulating or passing through the reefer machine and guided from the evaporator is divided into ducts at both sides of the container.       
 
         [0007]    The invention further relates to a method for loading a reefer container with pallets. 
         [0008]    When constructing reefer containers for shipping goods it is common that a reefer machine for the reefer container have been manufactured and sold by different companies. The reefer machine has been installed in the front frame of the container by means of bolts or rivets or similar fastening means. 
         [0009]    A frame for supporting the reefer machine in the container has usually been manufactured in aluminium, and the front frame of the container has been built in steel. 
         [0010]    The reefer machines used for reefer containers have so far always been provided with a plenum for the cold air delivery on a back side of the reefer machine. 
         [0011]    Once the reefer machine is installed in the container, there is a void on both sides of the machine. 
         [0012]    These voids, commonly called lockers, have traditionally been used for storage of temperature sensors etc. 
         [0013]    When manufacturing of both frame and machine, it is more convenient to integrate reefer machine and container, hence omitting the aluminium frame for the machine, which is then built into and integrated with the front end wall of the container. This offers obvious advantages like improved air tightness and insulation values. 
         [0014]    From U.S. Pat. No. 3,699,870 is disclosed a shipping container comprising a cooling machine where the evaporator is placed above the fans and the fans (centrifugal blowers) are arranged between the evaporator housing and the diffuser sections (ducts) blowing a mixture of air into the diffuser sections (ducts) at both sides of the container. 
         [0015]    Evaporator fans used in reefer machines has normally been powered by traditional asynchronous motors and the evaporator fans is normally placed in a plate above an evaporator, thereby pushing the air through the evaporator. The plate separates the intake air from the evaporator. Such a prior art arrangement is shown in  FIG. 1 . 
         [0016]    A further disadvantage by using asynchronous motors is that they are producing too much heat due to their low efficiency. In order to compensate for this undesirable add-on heat, the evaporator needs to run at a lower temperature which will cause a lowering of the relative humidity in the supply air. 
         [0017]    Regarding the products shipped in reefer containers it is for most produce important to keep the humidity level as high as possible in order to prevent dehumidification of the produce. Therefore it may be necessary to add humidity to the air within the container to ensure a sufficient humidity level to avoid the problem of dehumidification of the produce. Such adding of humidity to the air within the container will require additional equipment to each container or group of containers and will therefore be of great disadvantage. 
       SUMMARY OF THE INVENTION 
       [0018]    The overall purpose of creating more space for cargo within the container can be obtained by redesigning the reefer machine. 
         [0019]    Such redesigning opens up for utilizing the voids (lockers) on both sides of the machine. 
         [0020]    In one embodiment the width of the evaporator is extended to full width or near full width of the interior of the container. This provides also the possibility of directing the airflow into side-channels instead of using the state of the art solution which would be to use a plenum on the back side of the machine. 
         [0021]    Placing the evaporator above the fan or fans and thereby sucking the air through the evaporator instead of pushing it through, provides a better distribution of air through the evaporator. 
         [0022]    A combination of the above mentioned features leads to an increased efficiency of the fan. This solution is possible in that the one or more evaporator fans are placed in one or more ducts and that the one or more fan motors can be controlled. When more fans and fan motors are used, each fan motor can be controlled together with the other fan motors within the container or independently. 
         [0023]    By dividing the air guided from the evaporator into ducts at both sides of the container, it is possible to increase the internal cargo space. 
         [0024]    This is further achieved by that the ducts are arranged between a central part of the reefer machine and a sidewall of the container. 
         [0025]    Further the fan or fans being placed in one or more ducts raise the fan efficiency. 
         [0026]    The overall aim of the invention is to gain more space within the reefer container to be able to make room for more goods. 
         [0027]    Thereby the loading capability of a standard the container is increased. 
         [0028]    If loading the container with goods on pallets, placement of a single more pallet within a standard large reefer container will increase the loading capability with approximately 5%. 
         [0029]    The improved design makes it possible to design the reefer machine in a narrower layout than ordinary reefer machines. Further a redesign of the door or doors of the reefer container where also a narrower layout of doors are obtained, enough space are gained within the container to rearrange the positions of pallets within the container to arrange for at least one more of such pallets in the container. 
         [0030]    Doors on reefer containers are traditionally constructed as a sandwich construction with an outer steel panel, an inner lining of aluminium or stainless steel and an insulating material in the core, often polyurethane foam. In order to provide the necessary strength, reinforcement profiles are added to the outer steel panel and extending into the foam. A door constructed after this known principle is shown in  FIG. 10 . 
         [0031]    The internal reinforcement profiles make the construction more complicated due to extra components, whereby weight and cost is increased. Secondly these internal reinforcements protrude into the isolative core, reducing the insulation value of the door by forming a thermal bridge. 
         [0032]    A typical thickness of a reefer door is 75-90 mm. Additionally a door locking gear is bolted onto this door sandwich, further increasing door thickness. 
         [0033]    In a new door layout the internal door reinforcement profiles are removed and an outer corrugated door panel is provided instead. This simplifies the construction by reducing components, whereby weight and cost is reduced. 
         [0034]    In an embodiment of a new door the thickness of the isolating foam layer corresponds to a distance from the inner lining of the door to a protruding end of the internal reinforcement profiles of a door according to prior art. 
         [0035]    A corrugated door panel will allow the door locking gear to be placed between the corrugations, reducing the total thickness of the door. Placing locking gear on level with the outer door panel will protect them from impact and reduce the risk of damage. 
         [0036]    As there are no longer protruding metal reinforcement profiles in the isolative core, the insulation value of the door sandwich is the same as a traditional door design, even though the door panel provided with depressions reduces sandwich thickness. 
         [0037]    The thin door design will maintain same insulating value, while reducing overall thickness and protecting the locking gear. 
         [0038]    In an embodiment of a door for a reefer container, where a panel forming the outer side of the door is provided with one or more depressions, which depressions extend in a substantially vertical direction. 
         [0039]    In an embodiment the thickness of an isolating foam layer corresponds to a distance between the inner lining of a prior art door to a protruding end of the internal reinforcement profiles. 
         [0040]    A door panel provided with depressions will allow a door locking gear to be placed in a depression, reducing the total thickness of the door. Placing locking gear on level with the outer door panel will protect them from impact and reduce the risk of damage. 
         [0041]    As there are no longer protruding metal reinforcement profiles in the isolative core, the insulation value of the door sandwich is the same as a traditional door design, even though the door panel provided with depressions reduces sandwich thickness. 
         [0042]    The thin door design will maintain same insulating value, while reducing overall thickness and protecting the locking gear. 
         [0043]    In an embodiment the depressions in the door protrudes into the core of insulating material, which supports the strength and stability of the door. 
         [0044]    In another embodiment the insulating material comprises polyurethane foam. 
         [0045]    The door is provided with a locking gear placed in one or more depressions, which locking gear comprises a locking rod and a handle for operating the locking rod into a locked position by sliding the locking rod into a grove or hole in an upper and/or lower part of the container to be able to close the door or doors. 
         [0046]    In another embodiment the locking gear is provided with one or more handles, which handles are placed within the depression in a locked position. 
         [0047]    In another embodiment the outer side of the door comprises a panel made of steel. 
         [0048]    The inner lining is placed in a frame forming the outer perimeter of the door. The lining can be fastened to the frame by screws, rivets, bolts, welding or by use of other mechanical means. The lining can be fastened to the frame by using adhesive components. The lining can also be fastened by the adhesive effect from foaming of the isolating material in the core of the door or a combination of both fastening methods. 
         [0049]    The outer side of the door can be fastened to the frame in similar manner. 
         [0050]    In another embodiment the inner side of the door comprises a lining of aluminium. 
         [0051]    In another embodiment the inner side of the door comprises a lining of stainless steel. 
         [0052]    In an alternative embodiment the inner side of the door comprises a lining of fibreglass. 
         [0053]    In an alternative embodiment the inner side of the door comprises a lining of thermoplastics. 
         [0054]    In an alternative embodiment the inner side of the door comprises a lining of thermosetting resin. 
         [0055]    In an alternative embodiment the inner side of the door comprises a lining of thermosetting plastic. 
         [0056]    In another embodiment the inner side of the door comprises a lining of fiber reinforced plastics. 
         [0057]    In another embodiment one or more hinges is fastened to a depression of the door. 
         [0058]    In an alternative embodiment one or more hinges are fastened to an internal side of the door through a slot in an edge portion of the door. 
         [0059]    The invention is also achieved by a method for loading a reefer container with pallets, where at least eleven pallets of ISO 2 type or fourteen pallets of ISO 1 type are placed in the container with a longitudinal direction of the pallets going in a direction crosswise in direction of a longitudinal direction of the container and at least ten pallets of ISO 2 type or ten pallets of ISO 1 type are placed in the container with the longitudinal direction of the pallets going in a direction parallel with the longitudinal direction the container. 
         [0060]    In an embodiment of the method the pallets of ISO 2 type are placed in two rows within the container, a first row comprising nine pallets placed in the container with a longitudinal direction of the pallets going in a direction crosswise in relation to a longitudinal direction of the container and two pallets placed in the container with the longitudinal direction of the pallets going in a direction parallel with the longitudinal direction the container and a second row comprising eight pallets placed in the container with the longitudinal direction of the pallets going in a direction parallel with the longitudinal direction the container and two pallets placed in the container with a longitudinal direction of the pallets going in a direction crosswise in relation to a longitudinal direction of the container. 
         [0061]    A container according to the invention loaded with goods on pallets according to the above, can contain a pallet more than known containers. 
         [0062]    By installing evaporator fan motors downstream from the evaporator, the fans are highly exposed to cold air, high air velocities and various humidity levels. All combinations of the above may arise around the evaporator fan motors causing frost and ice to form on wings of the fan, on walls of air channels, on brackets etc. To prevent water from dripping directly or indirectly to areas close to the fan one or more water traps are placed below the evaporator. Water from the water traps can be drained and discharged to the outside of the container or the water can be reintroduced into the environment in the container to maintain a certain humidity level. Furthermore, water from drain blockage, leftover water overflow from above placed water traps might contribute to the start of ice building in the air channels. To reduce accumulation of water and ice at unexpected places around the water trap, in the air channels, around the fan motors and at a bottom T-floor during long trips, the defrost function is further provided with heaters placed in the air channel surface near each evaporator fan motor. 
         [0063]    These heaters can be energised along with the traditional evaporator heaters (placed just below the evaporator coil) or they can be energised separately, fully or in pulses, whichever is required in the situation. 
         [0064]    Usually the evaporator fan motors are stopped during a defrost session to allow warm air and heat from the energised heaters to pass upwards through the ice blocked evaporator. Since the traditional transport container refrigeration system has evaporator motors placed above the evaporator, the ice issue around the fan wings and fan motors are not creating problems. 
         [0065]    When the evaporator fans are installed below the evaporator, the possible water leaks and ice building around the fans could be thawed by the heaters, but if the fan motors are allowed to run slowly in either forward or reverse direction at the same time, heat distribution will increase in the air channels, below the evaporator and through the evaporator. However, the air flow should be kept at such a level that the heat does not enter the cargo space. 
         [0066]    This is achieved by a defrost system where heating elements are provided in a duct at a perimeter of the fan, or at a rim surrounding the fan at its perimeter. 
         [0067]    In an embodiment one or more evaporator heaters are placed below the evaporator coil or coils. 
         [0068]    In an alternative embodiment the heating elements can be energised separately, fully or in pulses, adapted to the situation. 
         [0069]    In an alternative embodiment hereof, the fan or fans are provided with heating elements in fan blades or wings. 
         [0070]    In an alternative embodiment a hub of the fan can be provided with heating elements and heat from the hub is transferred to the blades or wings of the fan due to the heat transmission of the selected materials or heat transmitting materials provided within the blades or wings of the fan. 
         [0071]    In an alternative embodiment the fan or fans are powered by permanent magnet motors. 
         [0072]    In an alternative embodiment a protruding surface and an edge forming a trap for trapping liquid or ice is provided above the one or more fans. 
         [0073]    In an alternative embodiment the edge has a rounded shape. 
         [0074]    In an alternative embodiment the edge forms a groove or gutter for collection of water and ice. 
         [0075]    In an alternative embodiment power draft of the one or more fan motors are monitored and an increase in power draft implies that the heating elements are following activated. 
         [0076]    In an alternative embodiment the fan or fans are arranged together with a motor in a unit for removal or exchange during maintenance. 
         [0077]    Ice forming can be reduced when fan motors are allowed to run slowly in either forward and/or reverse direction at the same time increasing the heat distribution in air channels or ducts, below the evaporator and through the evaporator, and keeping air flow at a sufficient low level ensuring that only little heat, preferably no heat enters a cargo space in the container. 
         [0078]    In an embodiment of the method fan motors are run in such a way that the heated air is circulated within the refrigerating system by letting one fan blow heated air in one direction and let another fan blow heated air in the opposite direction. 
         [0079]    Thereby is achieved that the heated air can circulate through the air channels or ducts and through the evaporator, without entering the cargo space. 
         [0080]    In a further embodiment of the method the heating elements for heating the ducts in an area near to the fan are energised separately. 
         [0081]    In an alternative embodiment the heating elements in the ducts can be energised separately from each other. 
         [0082]    Hereby it is possible to energise one heating element or one group of heating elements situated close to one of the fans at a time. 
         [0083]    In yet an embodiment of the method the heating elements are energised in pulses. 
         [0084]    Fan wing ice block prevention is a feature used to protect the evaporator fan motors when starting in cold ambient temperatures or in other situations, which has consequences in terms of ice building on or near the evaporator fan wings. Torque and power consumption of the motors, when the evaporator fan motors are energised for the first time during a start-up procedure is measured and should be below predefined limits. If torque on a motor reaches a predefined limit and the power consumption at the same time is above a certain level, the fan blades or wings are most likely blocked by ice, which will then energise the heating elements incorporated in the walls of the air ducts and placed near the blades or wings and motors as a mean to thaw the ice and after a short while try to start the motor again. 
         [0085]    One or more ducts can be provided with a guiding system in a maintenance or service opening in the duct for guiding and supporting a fan unit within the duct. The guiding system can be provided by a notch or groove in the perimeter of the duct and a corresponding ridge or spline provided at the rim of the fan unit or vice versa. Hereby it is obtained that the unit will be placed correct in the duct for example after removal due to maintenance and that the unit will not be able to dislocate during operation. 
         [0086]    The fan unit is powered by electrical wires and a plug and socket can be provided within the service opening making it possible to disconnect the wire and to remove the fan and motor as a unit. 
         [0087]    The wiring can be fastened to fastening elements by means of one or more struts or ribs fastening the fan motor to the rim or the wiring can be established through the one or more struts or ribs. 
         [0088]    In an alternative embodiment the power can be provided to the fan motor through connectors (not shown) moulded into one or more struts or ribs connecting the fan motor to the rim. 
         [0089]    To close the service opening and to ensure adequate performance of flow of air in the duct or ducts an insert is provided with an inner part having a shape corresponding to the duct in such a way that the insert forms part forms part of the duct when inserted in the duct. The insert can be provided with a plate for giving the insert a plane outer surface which is substantially level with the outer surface of the reefer machine. 
         [0090]    In traditional reefer machines the back plate of the air duct is installed by means of screws or rivets, why demounting the back plate is a complicated and time demanding process, which normally is done only in connection with repairs and not for e.g. cleaning purposes. 
         [0091]    As there is a growing awareness of hygiene, also in connection with reefers, Accessibility to hidden areas is required. 
         [0092]    By installing an openable hatch covering the evaporator, both the ducts and the evaporator is accessible for easy cleaning. 
         [0093]    Further embodiments and advantages are disclosed below in the description and in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0094]    The invention will now be described more fully below, by way of example only, with reference to the accompanying drawings, in which: 
           [0095]      FIG. 1  shows schematically a prior art arrangement of a reefer machine for a reefer container; 
           [0096]      FIG. 2  shows schematically airflow through an arrangement of a reefer machine for a reefer container according to the invention; 
           [0097]      FIG. 3  shows schematically re-circulated airflow through an arrangement of a reefer machine for a reefer container according to an embodiment of the invention; 
           [0098]      FIG. 4  shows schematically a loading scheme for ISO 2 pallets in a container relating to prior art; 
           [0099]      FIG. 5  shows schematically an alternative loading scheme for ISO 2 pallets in a container relating to prior art: 
           [0100]      FIG. 6  shows schematically a loading scheme for ISO 1 pallets in a container relating to prior art: 
           [0101]      FIG. 7  shows schematically a loading scheme for ISO 2 pallets in a container according to the invention; 
           [0102]      FIG. 8  shows schematically a loading scheme for ISO 1 pallets in a container according to the invention; 
           [0103]      FIG. 9  shows schematically an embodiment of a loading scheme for ISO 1 pallets in a container according to the invention; 
           [0104]      FIG. 10  shows schematically another embodiment of a loading scheme for ISO 1 pallets in a container according to the invention; 
           [0105]      FIG. 11  shows a door for a reefer container relating to prior art; 
           [0106]      FIG. 12  shows a door for a reefer container according to the invention; 
           [0107]      FIG. 13  shows schematically the refrigeration system of a reefer container from  FIG. 2 , showing in detail an embodiment of a part of a labyrinth or water trap having a protruding surface with a rounded edge; 
           [0108]      FIG. 14  shows schematically the refrigeration system of a reefer container from  FIG. 2 , showing in detail an embodiment of a part of a labyrinth or water trap having an edge with a rounded shape; 
           [0109]      FIG. 15  shows a reefer machine to be placed in the front end of a reefer container, which reefer machine is provided with openings for insertion and removal of one or more fans; and 
           [0110]      FIG. 16  shows an enlarged view of an opening showed in  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION 
       [0111]    Now convenient embodiments of the invention will be described. 
         [0112]    A reefer machine  1  for a reefer container  14  according to prior art is schematically shown in  FIG. 1 . Evaporator fans  2  is normally placed in a plate (not shown) above an evaporator  3 , thereby pushing air through the evaporator  3 . The plate separates intake air from the evaporator  3 . Such a prior art arrangement is shown in  FIG. 1 . 
         [0113]    Air  4  (shown by arrows) pushed through the evaporator  3  by the fans  2  is lead downwards through a central portion or plenum  5  of the reefer machine  1  and to a lower part  7  of the reefer machine  1  from where the air  4  is lead through a floor portion (not shown) of the container. The floor portion of the container  14  is normally made as a T-floor with a plurality of grooves between T-shaped protrusions standing on a base, which grooves runs in a lengthwise direction of the container  14  whereby the T-shaped protrusions, forms a distance between the base and cargo placed on pallets on the floor of the container  14 . 
         [0114]    At each side of the plenum  5  of the reefer machine  1  is a void called a locker  6 . These voids or lockers  6  can for example be used for temperature sensors or the like. Generally the space in the lockers  6  is not utilised optimally. 
         [0115]    According to the invention more space within the container  14  is provided hence making it possible to place at least one more pallet of ISO type  15  or one more pallet of EUR type  16  within the container  14 . 
         [0116]    The overall purpose of creating more space for cargo within the container  14  can be obtained by redesigning the reefer machine  1 . 
         [0117]    Such redesigning opens up for utilizing the voids or lockers  6  on both sides of the machine  1 . 
         [0118]    In one embodiment the width of the evaporator  3  is extended to full width or near full width of the interior of the container  14 . This provides also the possibility of directing the airflow  4  into side-channels instead of using the state of the art solution which would be to use a plenum  5  on the back side of the machine  1 . 
         [0119]    Placing the evaporator  3  above the fan or fans  2  and thereby sucking the air  4  through the evaporator  3  instead of pushing it through, shows that a better distribution of air  4  through the evaporator  3  is obtained. 
         [0120]    A combination of the above mentioned features leads to an increased efficiency of the fan  2 . This solution is possible in that the one or more evaporator fans  2  are placed in one or more ducts  8  and that the one or more fan motors  19  can be controlled. 
         [0121]    By dividing the air  4  guided from the evaporator  3  into ducts  8  at both sides of the container  14 , it is possible to increase the internal cargo space. When the internal cargo space is increased, it is possible to load the container  14  with pallets  15 ,  16  in standard measures in different ways compared to loading schemes for use in containers according to prior art. 
         [0122]    The ducts  8  are arranged between a central part  12  of the reefer machine  1  and a side or wall of the container  14  as shown in  FIG. 2 . Here the ducts  8  are arranged at both sides of the reefer machine  1 . 
         [0123]    The central part  12  of the reefer machine  1  comprises at its outer side components (not shown) for operation of the reefer machine  1 . 
         [0124]    Hereby it is possible for the reefer machine  1  to have an extension in longitudinal direction of the container  14 , which is smaller than a reefer machine in a container according to prior art. 
         [0125]    Further the fan or fans  2  being placed in one or more ducts  8  raise the fan efficiency. 
         [0126]    The overall aim of the invention is to gain more space within the reefer container  14  to be able to make room for more pallets  15 ,  16 . 
         [0127]    Placement of one more pallet  15 ,  16  within a standard large reefer container will increase the loading capability with approximately 5%. 
         [0128]    The improved design makes it possible to design the reefer machine  1  in a narrower layout than ordinary reefer machines  1 . 
         [0129]    Further a redesign of a door or doors  25  of the reefer container  14 , where also a narrower layout of doors  25  are obtained, enough space are gained within the container  14  to rearrange the positions of pallets  15 ,  16  within the container  14  to arrange for at least one more of such pallets  15 ,  16  in the container  14 . 
         [0130]    It is possible to load more pallets in a container by a method for loading a reefer container with pallets, where at least eleven pallets  15  of ISO 2 type (the standard size of such pallets should be approximately 1200×1000 mm) or fourteen pallets  16  of ISO 1 type corresponding to EUR type (the standard size of such pallets should be approximately 800×1200 mm) are placed in the container  14  with a longitudinal direction of the pallets  15 ,  16  going in a direction crosswise in relation to a longitudinal direction of the container  14  and at least ten pallets  15  of ISO 2 type or ten pallets  16  of ISO 1 type are placed in the container  14  with the longitudinal direction of the pallets  15 ,  16  going in a direction parallel with the longitudinal direction the container  14 . 
         [0131]    In an embodiment of the method the pallets  15  of ISO 2 type are placed in two rows within the container  14 , a first row comprising nine pallets  15  placed in the container  14  with a longitudinal direction of the pallets  15  going in a direction crosswise in relation to a longitudinal direction of the container  14  and two pallets  15  placed in the container  14  with the longitudinal direction of the pallets  15  going in a direction parallel with the longitudinal direction the container  14  and a second row comprising eight pallets  15  placed in the container  14  with the longitudinal direction of the pallets  15  going in a direction parallel with the longitudinal direction the container  14  and two pallets  15  placed in the container  14  with a longitudinal direction of the pallets going in a direction crosswise in relation to a longitudinal direction of the container  14 . 
         [0132]    Loading of a container with ISO 1 type pallets can be performed in three advantageous ways. If pallets  16  placed in the container  14  with a longitudinal direction of the pallets  16  going in a direction crosswise in relation to a longitudinal direction of the container  14  are given a reference A and pallets  16  placed in the container  14  with the longitudinal direction of the pallets  16  going in a direction parallel with the longitudinal direction the container are given a reference B, three advantageous loading schemes can be expressed as follows, when pallets are placed in two rows in the longitudinal direction of the container  14  as shown in  FIGS. 8-10 :
       1) A-A-A-A-A-A-A-A-A-A-A-A-A-B for one row and B-B-B-B-B-B-B-B-B-A for the second row;   2) A-A-A-B-B-B-B-B-B-B-A for one row and B-B-A-A-A-A-A-A-A-A-A-A-B for the second row; and   3) B-B-A-A-A-A-A-A-B-B-B-A for one row and A-A-A-B-B-B-B-A-A-A-A-B for the second row.       
 
         [0136]    Traditionally a door  25  for a reefer container  14  comprises a frame  33 , an outer steel panel  31 , an inner lining  32  of aluminium or stainless steel and a core  26 . An often used insulating material in the core  26  is polyurethane foam. In order to provide necessary strength to the door  25 , reinforcement profiles  27  are added to the outer steel panel  31  and extending into the foam of the core  26 . Additionally a door locking gear in shape of one or more hinges  28 , locking rods  29  and handles  30  are bolted onto the door  25 , further increasing door thickness since hinges  28 , locking rods  29  and handles  30  protrudes from an outer side of the door  25 . If these elements are to be kept level with an end portion of the container, the door  25  will have a certain protrusion into the container. A door constructed after this known principle is shown in  FIG. 10 . 
         [0137]    A redesign of a door or doors  25  for a reefer container  14  (not shown in  FIGS. 9 and 10 ) with a more narrow layout of doors  25  is shown in  FIG. 11 . Such new doors are redesigned for providing enough space within the container to rearrange positioning of goods or goods placed on pallets  15 ,  16  within the container  14  to arrange for more goods or at least one more of such pallets  15 ,  16  in the container  14 . 
         [0138]    The aim of the invention is to be able to provide a door  25  which is narrower, having same isolating capacity and which is at least as stable as a traditional door  25 . 
         [0139]    Internal reinforcement profiles  27  make the construction more complicated due to extra components, whereby weight and cost is increased. Secondly these internal reinforcements  27  protrude into the isolative core  26 , reducing the insulation value of the door  25  by forming a thermal bridge. 
         [0140]    A typical thickness of a reefer door  25  is 75-90 mm. 
         [0141]    In a new door layout the internal door reinforcement profiles  27  are removed and an outer door panel  31  is provided with depressions  34  instead. This simplifies the construction by reducing components, whereby weight and cost is reduced. 
         [0142]    In an embodiment the thickness of the isolating foam layer  26  corresponds to a distance between the inner lining of the door  25  to a protruding end of the internal reinforcement profiles  27  in the prior art doors  25 . 
         [0143]    In a new door  25  for a reefer container, the door comprises a frame  33  to which is fastened an outer panel  31  and an inner lining  32 , a core  26  of insulating material, one or more hinges  28  and locking gear  29 ,  30 , where the outer panel  31  of the door  25  is provided with one or more depressions  34 , which depressions extends in a substantially vertical direction. 
         [0144]    The inner lining  32  is placed in a frame  33  forming an outer perimeter of the door  25 . The lining  32  can be fastened to the frame  33  by screws, rivets, bolts, clamping, welding or by using adhesive components. The lining  32  can also be fastened by an adhesive effect from foaming of the isolating material in the core  26  of the door  25  or a combination of the above fastening methods. 
         [0145]    The outer panel  31  of the door  25  can be fastened to the frame  33  in similar manner. 
         [0146]    In an embodiment the depressions  34  in the door  25  protrude into the core  26  of insulating material. 
         [0147]    In an embodiment the insulating material comprises polyurethane foam. 
         [0148]    In an embodiment the door  25  is provided with a locking gear  29 ,  30  placed in one or more depressions  34 , which locking gear  29 ,  30  comprises a locking rod  29  and a handle  30  for operating the locking rod  29  into a locked position by sliding the locking rod  29  into a grove or hole in an upper and/or lower part of the container to be able to close the door or doors  25 . 
         [0149]    In an embodiment the locking gear  29 ,  30  is provided with one or more handles  30 , which handles  30  are placed within the depression  34  in a locked position. 
         [0150]    In an embodiment the outer side of the door  25  comprises a panel  31  made of steel or another strong material able to withstand rough handling during transport and during loading and unloading of the container. 
         [0151]    Other examples of materials suitable for the outer side of the door can be aluminium or composite materials. 
         [0152]    In an embodiment the inner side of the door  25  comprises a lining  32  of aluminium. 
         [0153]    In an embodiment the inner side of the door  25  comprises a lining  32  of stainless steel. 
         [0154]    In an embodiment one or more hinges  28  are fastened to a depression  34  of the door  25 . 
         [0155]    In an embodiment one or more hinges  28  are fastened to an internal side of the door  25  through a slot in an edge portion of the door  25  or in the frame  33 . 
         [0156]    A door panel  31  with one or more depressions  34  will allow the door locking gear  29 ,  30  to be placed in a depression  34 , reducing the total thickness of the door  25 . Placing locking gear  29 ,  30  in a depression  34  and thereby on level with the outer side of the door panel  31  will further protect them from impact and reduce the risk of damage. 
         [0157]    The locking gear  29 ,  30  comprises a locking rod  29  and a handle  30  for operating the locking rod  29  into a locked position by sliding the locking rod  29  into a grove or hole in the upper and/or lower part of the container to be able to close the door or doors  25  in a secure manner. The locking rod  29  can be guided for sliding by commonly known sleeves, bushings or similar fittings  35 . 
         [0158]    One or more hinges  28  are placed on the door  25  at a place at an outer edge where the thickness of the door  25  is reduced, for example by means of a Depression  34 . The hinge  28  could also be fastened to the door  25  by fastening the part of the hinge  28 , which is fastened to the reduced thickness or depression of the door  25 , on an internal side of the door  25  through a slot in an edge portion or the frame  33  of the door  25 . Thereby the fastening part of the hinge will be adjacent to the core  26  of isolating material. 
         [0159]    As there are no longer protruding metal parts  27  in the isolative core  26 , the insulation value of the door sandwich is the same as a traditional door design, even though the door panel  31  provided with depressions  34  reduces sandwich thickness. Hereby is achieved that the door  25  will have a protrusion into the container, which is smaller than the protrusion of a conventional door design. 
         [0160]    The thin door design will maintain same insulating value, while reducing overall thickness and protecting the locking gear  29 ,  30 . 
         [0161]    Placing the fans  2  below the evaporator  3  can generate a problem since water (ice) can drip or fall down on the fan  2  wings from the evaporator  3  or other surfaces placed above the fan  3 . This can lead to blockage or imbalance of the fan  2 . 
         [0162]    By shaping an area above the duct  8  and below the evaporator  3  as a “labyrinth” or trap (see  FIGS. 2, 13 and 14 ), water is prevented from dripping directly down on the fan  2 . 
         [0163]    The trap can be provided by a surface  9  protruding into the reefer machine  1  Further a central part  12  of the reefer machine  1  is formed with its upper part having inclining sides  120  inclining from an area  121  substantially in the middle part of the central part  12  and downwards towards the ducts  8 . 
         [0164]    To prevent water or ice from dripping from the inclining sides and into the ducts  8  a slightly ascending portion is provided on an edge  119  of the surface  9  protruding into the reefer machine  1  and an edge  10  is provided in a transition area of the central part  12  where the downwards inclining side  120  goes into a more upwards direction and forms a part of the duct  8  or the ducts  8  adjoins the transition area of the inclining side  120 . 
         [0165]    In an embodiment the edge  119  has a rounded shape. The more an outer end of the edge is ascending and thereby forming a groove or gutter for collection of water and ice, the more it is able to hold back water or ice from falling from the evaporator  3  and into the duct  8 . 
         [0166]    The edge  10  prevents water or ice from entering the duct  8  and protruding surfaces  9  ensures that water or ice dripping from the evaporator  3  will be lead onto the inclining surfaces  120 . A drain (not shown) is provided near the edge  10  to be able to lead the water and thawed ice into a reservoir (not shown) or to outside of the container. 
         [0167]    In an embodiment the edge  10  has a rounded shape. 
         [0168]    If the edge  10  is sharp, it is more convenient to stop and collect water in the trap, but the airflow in the system will be more turbulent. If the edge is rounded and thereby the edge  10  being less sharp, the airflow will be more laminar which will lead to a more optimal airflow. Therefore in situations where the airflow is more important than the water collection a rounded edge  10  is chosen, and in situations where water collection is more important than the airflow, a more sharp edge  10  is chosen. 
         [0169]    The same apply to the edge  119 . 
         [0170]    To reduce accumulation of water and ice at unexpected places around the water trap  9 ,  10 , in the air channels  80  or ducts  8 , around the fan motors and at a bottom T-floor (not shown) during long trips, the defrost function is further provided with heaters placed in the air duct  8  surface  11  near each evaporator fan motor. 
         [0171]    If the above mentioned combinations of conditions of air and humidity should cause ice forming in the duct  8 , especially on the fan blades or wings or near the fan  2 , heating elements are provided for thawing the ice. 
         [0172]    By building in one or more heating elements in the duct  8  at a perimeter  20  of the fan, or at a rim  200  surrounding the fan  2  at its perimeter, any ice build-up can effectively be removed by heating up the element. Typically this will happen simultaneous with general defrosting of the evaporator  3 . 
         [0173]    If power draft of one or more fan motors  19  is monitored and an increase in power draft is detected, the system can imply that heating elements are activated. The activation can be initiated by detection of one or more of following situations as an example: the fan  2  needs excessive power to run, the fan  2  runs too slow in relation to the power input to the motor  19 , the fan  2  is blocked, and/or the fan  2  is wobbling. These situations can be symptoms of ice generated on or near the fan  2  or fan blades or wings. To avoid such ice building in the duct or ducts  8 , one or more heating elements  11  are placed near the fan or fans  2  to be able to thaw the ice. This can also be used as an alert that one or more motors  19  are too heavy loaded for some reason (dirt or foreign objects blocking the fan  2 ). 
         [0174]    If ice is formed in the duct  8  or on fan blades or wings, one or more heating wires or heating elements  11  provided in a duct  8  at a perimeter  20  of the fan  2 , or at a rim  200  surrounding the fan  2  at its perimeter can be activated to heat the fan blades or wings or the area of the duct  8  surrounding the fan  2  or at the rim  200  surrounding the fan  2  at its perimeter  20  and thereby thaw the ice. 
         [0175]    In an embodiment one or more evaporator heaters  110  are placed below the evaporator coil or coils  3 . 
         [0176]    In another embodiment the heating elements  11 ,  110  can be energised separately, fully or in pulses, adapted to the situation. 
         [0177]    In a further embodiment the heating elements  11  can be energised separately to heat a duct  8  at a perimeter  20  of the fan  2 , or at a rim  200  surrounding the fan  2  at its perimeter  20  at a time. 
         [0178]    In an alternative embodiment the fan or fans  2  are powered by permanent magnet motors  19 . 
         [0179]    In yet an alternative embodiment, the fan can be provided with heating elements in the fan blades or wings. The energy can be transferred to the heating elements in the fan blades or wings by ordinary commutators or the energy can be transferred by induction. 
         [0180]    In an alternative embodiment a protruding surface  9  and an edge  10  forming a trap for trapping liquid or ice is provided above the one or more fans  2 . 
         [0181]    In an alternative embodiment power draft of the one or more fan motors  19  are monitored and an increase in power draft imply that the heating elements are following activated. 
         [0182]    In an alternative embodiment fan or fans  2  are arranged together with a motor  19  in a unit  180  for removal or exchange during maintenance. 
         [0183]    In certain situations the system can be put into defrosting mode. In an embodiment the defrosting mode is entered by letting a fan  2  direct the airflow  4  in one direction and another fan  2  direct the airflow  4  in another direction, thereby letting the airflow  4  circulate within the cooling engine. If one fan is blowing the air in a downwards direction, the other fan is set to blow the air in an upwards direction as shown in  FIG. 3 . 
         [0184]    In conventional reefer machines defrosting mode is entered by heating the air  4  blown through the evaporator  3 . This method can cause that heated air is blown into the cargo space thereby raising the temperature in the environment already cooled down. 
         [0185]    According to the new method it is possible to circulate the heated air within the reefer machine  1  without having the heated air entering the cargo space. Hereby is achieved a more expedient way to enter defrosting mode of the reefer machine  1 . 
         [0186]    This is possible in that fan motors  19  are allowed to run slowly in either forward and/or reverse direction at the same time increasing the heat distribution in air channels  80  or ducts  8 , below the evaporator  3  and through the evaporator  3 , and keeping air flow  4  at a sufficient low level ensuring that only little heat, preferably no heat enters a cargo space in the container. 
         [0187]    In an embodiment the fan motors  19  are run in such a way that the heated air is circulated within the refrigerating system  1  by letting one fan  2  blow heated air in one direction and let another fan  2  blow heated air in the opposite direction. 
         [0188]    Thereby warm air will be circulated within the refrigerating system. This can be done for example by letting one fan  2  blow heated air in one direction and let another fan  2  blow heated air in the opposite direction. Thereby is achieved that the heated air can circulate through the air channels  80  or ducts  8  and through the evaporator  3 , without entering the cargo space. 
         [0189]    The heaters placed in the duct  8  at the perimeter  20  of the fan, or at the rim  200  surrounding the fan  2  at its perimeter, can be energised along with traditional evaporator heaters which is placed just below the evaporator coil (not shown) or they can be energised separately fully or in pulses, whichever is required in the situation. 
         [0190]    In an embodiment the heating elements  11  in the ducts  8  can be energised separately from each other. 
         [0191]    Thereby it is possible to only energise one heating element or group of heating elements  11  which relates to one duct  8 , if this duct forms ice in the area close to the fan  2 . 
         [0192]    By installing the evaporator fans  2  below the evaporator  3 , the possible water leaks and ice building around the fans  2  could be thawed by the heaters, but if the fan motors  19  are allowed to run slowly in either forward and/or reverse direction at the same time, heat distribution will increase in the air channels  80  or ducts  8 , below the evaporator  3  and through the evaporator  3 . However, the air flow  4  should be kept at such a level that the heat does not enter the cargo space. 
         [0193]    One or more ducts  8  can be provided with a guiding system  21 ,  22  in a maintenance or service opening  18  in the duct  8  for guiding and supporting a fan unit  180  within the duct  8 . The guiding system can be provided by a notch or groove  22  in the perimeter  20  of the duct  8  and a corresponding ridge or spline  21  provided at the rim  200  of the fan unit  180 . The notch or groove and ridge or spline can also be arranged the other way around. Hereby it is obtained that the unit will be placed correct in the duct for example after removal due to maintenance and that the unit will not be able to dislocate during operation. 
         [0194]    The fan unit  180  is powered by electrical wires and a plug and socket can be provided within the service opening  18  making it possible to disconnect the wire and to remove the fan and motor as a unit. 
         [0195]    The wiring can be fastened to fastening elements by means of one or more struts or ribs  191  fastening the fan motor  19  to the rim  200  or the wiring can be established through the one or more struts or ribs  191 . 
         [0196]    In an alternative embodiment the power can be provided to the fan motor  19  through connectors (not shown) moulded into one or more struts or ribs  191  connecting the fan motor  19  to the rim  200 . 
         [0197]    To close the service opening  18  and to ensure adequate performance of flow of air in the duct or ducts  8  an insert  23  is provided with an inner part having a shape corresponding to the duct  8  in such a way that the insert  23  forms part of the duct  8  when inserted in the duct  8 . The insert  23  can be provided with a plate  24  for giving the insert  23  a plane outer surface which is substantially level with the outer surface of the reefer machine  1 . 
         [0198]    In traditional reefer machines the back plate of the air duct is installed by means of screws or rivets, why demounting the back plate is a complicated and time demanding process, which normally is done only in connection with repairs and not for e.g. cleaning purposes. 
         [0199]    As there is a growing awareness of hygiene, also in connection with reefers, Accessibility to hidden areas is required. 
         [0200]    By installing an openable hatch (not shown) covering the evaporator, both the ducts and the evaporator is accessible for easy cleaning.