Patent Publication Number: US-10315839-B2

Title: Shipping container

Description:
TECHNICAL FIELD 
     The present invention relates to a shipping container for transporting cargo. More particularly, the present invention relates to a shipping container suitable for loading long objects such as lumber. 
     BACKGROUND ART 
     When transporting cargo in a shipping container, loading and unloading of the cargo into and out of the shipping container is carried out, as shown in JP 11-60187 A for example, through the opening formed by opening doors at the rear end of the shipping container (see FIG. 1 of JP 11-60187 A). In this case, a transport vehicle such as a forklift is used for the loading and unloading of the cargo. However, when transporting long objects such as lumber or steel materials, as cargo, there is a problem that a bundle of a plurality of such long objects may break during the loading and unloading thereof, and the end portions of the scattered long objects may come into contact with the inner surfaces of the shipping container, to cause damage to the inner surfaces or to the long objects themselves. In addition, loading and unloading of a large number of long objects into and out of the shipping container through the doors is a complicated operation, which consumes time and cost. 
     In view of this, it has been proposed to install a cargo bed for long objects to a transportation vehicle, as shown in JP 2015-696 A, for carrying out the transportation of long objects. This cargo bed includes a plurality of fall prevention columns vertically extending from both the right and left sides of its floor surface, at positions bilaterally symmetrical to each other (See e.g., FIG. 1 of JP 2015-696 A). The fall prevention columns serve to prevent the falling of the long objects loaded on the floor surface from the right and left sides of the floor surface. Since no top plate is provided on top of the fall prevention columns, the loading of the long objects can be carried out directly from above the cargo bed (see FIG. 6 in JP 2015-696 A). 
     However, the cargo bed for long objects disclosed in JP 2015-696 A is for use in a transportation vehicle such as a truck, and thus, in order to load long objects loaded on the cargo bed for long objects, into a container ship, it is necessary to unload the long objects from the cargo bed and to reload them into a shipping container. This reloading operation is extremely complicated, and causes an increase in the cost as a result thereof. In addition, there is a potential risk for other problems such as the occurrence of damage in the long objects during the reloading. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a shipping container into which long objects such as lumber can be efficiently loaded. 
     In order to solve the above mentioned problems, the present invention relates to a shipping container including: a bottom plate onto which cargo is to be placed; columns vertically extending from the bottom plate; and a top plate detachably supported by the columns. 
     Since the top plate in this shipping container is detachable from the columns, it is possible to smoothly load cargo from above the shipping container by detaching and removing the top plate when loading the cargo into the shipping container. When the loading is completed, the top plate is attached back to the columns again. By attaching the top plate to the columns, the columns, which are separately and vertically disposed, are integrally joined together by the top plate, thereby ensuring the strength of the shipping container as a whole. Therefore, a plurality of such shipping containers can be stacked one on top of another in a container ship, in the same manner as ordinary shipping containers. 
     Preferably, the top plate of this shipping container is formed with one or more than one insertion recess into which a jig or jigs used to attach and detach the top plate to and from the columns are inserted. By forming such insertion recess or recesses in the top plate, a jig or jigs (such as forks of a forklift) can be inserted into the insertion recess or recesses, to allow for easily attaching and detaching the top plate. 
     In each of the above-described constitutions, at least one of the plurality of columns, which support the top plate, may be in the shape of a ladder. Such a ladder-shaped column allows an operator to climb up this ladder-shaped column to the upper portion of the shipping container, and to confirm the state of the loaded cargo. All of the columns need not be in the shape of a ladder. For example, the columns disposed at three locations on each side, namely at the foremost portion, central portion, and rearmost portion on each side of the shipping container may be in the shape of a ladder. 
     Effect of the Invention 
     In the constitution according to the present invention, the shipping container includes: a bottom plate onto which cargo is to be placed; columns vertically extending from the bottom plate; and a top plate detachably supported by the columns. Since the top plate of this shipping container is detachable from the columns, it is possible to smoothly load cargo from above the shipping container, by detaching and removing the top plate when loading the cargo into the shipping container. When the loading is completed, the top plate is attached back to the columns again. By attaching the top plate to the columns, the columns, which are separately and vertically disposed, are integrally joined together by the top plate, thereby ensuring the strength of the shipping container as a whole. Therefore, a plurality of such shipping containers can be stacked one on top of another in a container ship, in the same manner as ordinary shipping containers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment of a shipping container according to the present invention. 
         FIG. 2  is a perspective view of the shipping container shown in  FIG. 1 , in a state in which its top plates are removed. 
         FIG. 3  is a front view of the shipping container of  FIG. 1 , illustrating an operation for removing the top plates. 
         FIGS. 4( a ) and 4( b )  are partial sectional views of the shipping container shown in  FIG. 1 , showing its locking mechanism, seen from the side: of which  FIG. 4 ( a )  shows a locked state of the locking mechanism; and  FIG. 4 ( b )  shows an unlocked state thereof. 
         FIG. 5  is a perspective view of the locking mechanism. 
         FIGS. 6( a )-6( c )  are vertical sectional views of the locking mechanism: of which  FIG. 6 ( a )  shows a state in which a column and the top plate are spaced apart from each other;  FIG. 6 ( b )  shows a state in which the column and the top plate are unlocked from each other; and  FIG. 6 ( c )  shows a state in which the column and the top plate are locked together. 
         FIG. 7  is a side view of the shipping container of  FIG. 1 , illustrating the process of loading of long objects into the shipping container. 
         FIG. 8  is a front view of the shipping container showing a state in which the long objects are fixed in position by wires. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of a shipping container according to the present invention is shown in  FIG. 1  and  FIG. 2 . This shipping container includes, as main components, a bottom plate  10 , columns  20 , and top plates  30 . Unlike an ordinary shipping container, this shipping container does not have side plates, and cargo C loaded within the shipping container can be seen through the openings between the columns  20  (see  FIG. 7 ). 
     The bottom plate  10  is a plate member in the shape of a rectangle, on top of which the cargo C is to be placed. The size of a shipping container is defined by international standards, and the bottom plate  10  is generally 20 feet or 40 feet long, and 8 feet wide, in accordance with the size defined in the international standards. A front plate  11  extends vertically from the front edge of the bottom plate  10 , doors  12 , which can be opened and closed extend vertically from the rear edge of the bottom plate  10 . Fixing jigs  13  are provided on both the right and left sides of the upper surface of the bottom plate  10 , spaced apart from each other at predetermined intervals (for example, at 1 m intervals). 
     The columns  20  consist of 14 vertically extending columns, seven of which are disposed on each of the right and left sides of the bottom plate  10 . Of the seven columns  20  on each side of the bottom plate  10 , the columns  20  ( 20   a ) disposed at the foremost portion, the central portion, and the rearmost portion of the bottom plate  10  are in the shape of a ladder. With this arrangement, an operator can easily check how the cargo C is loaded in the shipping container by climbing up one of the ladder-shaped columns  20  to the upper portion of the shipping container. Further, since the widths (lengths in the fore and aft direction) of the ladder-shaped columns  20  are usually larger than the widths of the other regular-shaped columns  20 , it is possible to more stably hold the cargo C in the shipping container. The lengths of the columns  20  are usually adjusted such that the height of the shipping container (with the top plates  30  being attached) is 8 feet and 6 inches. 
     The number of the columns  20  is not limited, and may be varied taking into consideration the weight of the top plates  30 , the required strength of the shipping container, and the like. The intervals between the adjacent pairs of columns  20  are preferably adjusted wider than the distance between the outer edges of the pair of forks of a commonly used forklift so that the cargo C can be easily loaded into the shipping container through its side, using a forklift. The columns  20  are preferably detachably attached to the bottom plate  10  so that the cargo C can be more easily loaded into the shipping container. 
     Engaging walls  21  are provided, respectively, at the front sides of the columns  20  ( 20   a ) disposed at the foremost portion of the shipping container (namely between the front plate  11  and the foremost columns  20  ( 20   a )), and at the rear sides of the columns  20  ( 20   a ) disposed at the rearmost portion of the shipping container (namely between the doors  12  and the rearmost columns  20  ( 20   a )). By providing the engaging walls  21 , both the end portions of the cargo C placed within the shipping container can be supported in the lateral direction (particularly if the cargo C consists of long objects). Thus, the engaging walls  21  make the cargo C less likely to be inclined diagonally within the shipping container, thus preventing the load of the cargo C from being applied only to a particular one or ones of the columns  20 . The widths (lengths in the fore and aft direction) of the engaging walls  21  are not limited, but are preferably from 30 to 80 cm. 
     While in the embodiment, the columns  20  ( 20   a ) at the foremost portion, central portion, and the rearmost portion of the shipping container are in the shape of a ladder, this is merely one example. That is, any one or ones of the 14 columns  20  may have the shape of a ladder, taking into consideration, for example, the convenience of checking how the cargo C is loaded in the shipping container. Alternatively, none of the columns  20  may have the shape of a ladder. 
     The top plates  30  cover the upper portion of the shipping container, and are detachable from the columns  20 . The top plates  30  are two separate top plate members  30   a  and  30   b  each half the size of the bottom plate  10  ((10 feet or 20 feet long, and 8 feet wide). While two top plates  30 , i.e., two separate top plate members  30   a  and  30   b , are used in this embodiment, a single integral top plate  30  may be used instead, if, for example, the shipping container has a short total length (e.g., 20 feet). 
     A pair of insertion recesses  31  are formed in each of the top plates  30  (separate top plate members  30   a  and  30   b ) to extend from side to side thereof. The interval between the pair of insertion recesses  31  is equal to the interval between the pair of forks F of the forklift shown in  FIG. 3  so that the forks F of the forklift can be inserted into the insertion recesses  31  of each top plate  30  forks F can be elevated and lowered, thereby allowing for easily attaching and detaching the top plate  30  (separate top plate member  30   a ,  30   b ) to and from the columns  20 . 
     The top plates  30  (separate top plate members  30   a  and  30   b ) have, in the lower surfaces thereof, fitting recesses  32  at positions corresponding to the positions of the respective columns  20 . The fitting recesses  32  are arranged and configured such that the upper ends of the columns  20  are fitted into the respective fitting recesses  32  (see  FIG. 2 ). By fitting the upper ends of the respective columns  20  into the fitting recesses  32 , it is possible, when the cargo C loaded within the shipping container leans against the columns  20 , to prevent the columns  20  from significantly bending outwardly due to the load of the cargo C. 
     Further, as shown in  FIG. 4 , a locking mechanism  40  is provided at least at one corner of each top plate  30  (separate top plate member  30   a ,  30   b ). The locking mechanism  40  is configured such that when the top plate  30  is placed on the corresponding columns  20 , and the top plate  30  is lowered and fitted to the columns  20  under its own weight, the locking mechanism  40  automatically locks the top plate  30  to the columns  20 . The locking mechanism  40  is further configured to automatically unlock the top plate  30  from the columns  20  when the forks F of a forklift are inserted into the insertion recesses  31  formed in the top plate  30 . 
     As shown in detail in  FIG. 5 , each locking mechanism  40  mainly includes: a first hook  41 , a second hook  42 , and an unlocking bar  43  all provided on the top plate  30 ; and an engaging piece  44  provided on one of the columns  20 . The first hook  41  is provided with a first engaging protrusion  41   a  and an engaging recess  41   b , and is biased in a first direction by a first biasing member  41   c . The second hook  42  is provided with a second engaging protrusion  42   a  and an abutment portion  42   b , and is biased by a second biasing member  42   c  in the first direction described above. The above described first direction is the clockwise direction in the figures, and the direction opposite to the above described first direction (i.e., a second direction) is the counterclockwise direction in the figures. The unlocking bar  43  extends into one of the insertion recesses  31  of the top plate  30 , while being in abutment with the abutment portion  42   b  of the second hook  42 , and is configured to be movable in the lateral direction (i.e., along the longitudinal axis of the top plate  30 ). 
     As shown in  FIGS. 6( a ) through 6( c ) , when the top plate  30  is lowered toward the columns  20 , the engaging piece  44  is inserted into a slit portion  45  of the locking mechanism  40 , and comes into contact with the inner surface of the engaging recess  41   b . This causes the first hook  41  to be rotated in the counterclockwise (second) direction against the biasing force of the first biasing member  41   c  (see  FIGS. 6 ( a ) and ( b ) ). When the engaging piece  44  is further inserted to a predetermined position, the second hook  42  is rotated in the clockwise (first or locking) direction under the biasing force of the second biasing member  42   c , thereby allowing the first engaging protrusion  41   a  of the first hook  41  and the second engaging protrusion  42   a  of the second hook  42  to be engaged with each other while holding the engaging piece  44  of the column  20 . In this manner, the top plate  30  is locked to the corresponding column  20  (see  FIG. 6 ( c ) ). 
     In this state, i.e., with the top plate  30  locked to the column  20 , when the forks F of a forklift are inserted into the insertion recesses  31  formed in the top plate  30 , the unlocking bar  43  is moved toward the second hook  42  by the fork F inserted in the one of the insertion recesses  31 , and the thus moved unlocking bar  43  pushes the abutment portion  42   b  of the second hook  42  in the counterclockwise (second) direction. This causes the second hook  42  to rotate in the counterclockwise (second) direction against the biasing force of the second biasing member  42   c , and the engagement between the first engaging protrusion  41   a  of the first hook  41  and the second engaging protrusion  42   a  of the second hook  42  is released. In this manner, the top plate  30  is unlocked from the corresponding column  20  (see  FIGS. 6  ( c ) to  6 ( b )). When the top plate  30  is moved upward after being unlocked from the columns  20 , the first hook  41  is rotated in the clockwise (first) direction under the biasing force of the first biasing member  41   c , and the engaging piece  44  disengages (is released) from the first hook  41  (see  FIG. 6 ( a ) ). 
     The configuration of the locking mechanisms  40  described above is merely an example, and it is also acceptable to provide other types of locking mechanisms, or to provide no locking mechanism at all. 
     By removing the top plates  30 , it is possible, as shown in  FIG. 7 , to easily load long objects such as lumber and the like into the shipping container, from above the container, using heavy equipment (not shown) such as a crane, or a forklift, thereby ensuring high operational efficiency. Further, since this shipping container can be stacked on other shipping containers in a container ship in the same manner as ordinary shipping containers, it is not necessary to unload the cargo which has been transported to the harbor by a truck, and reload it into a shipping container. This significantly reduces the steps and cost for loading cargo. 
     If the cargo C is long objects, wires  14  may be wrapped around the cargo C and hooked to the fixing jigs  13  on the right and left sides of the bottom plate to fix the cargo C, as shown in  FIG. 8 , so that the shifting of the cargo C during transportation can be prevented to enhance safety. 
     When importing and exporting raw wood, it is required that the raw wood be subjected to a disinfection treatment by fumigation, and be loaded into a ship, and the like, within a specified period of time (two weeks, for example) after the disinfection treatment. The fumigation treatment is carried out by: stacking the raw wood in a pile at a predetermined location; covering a sheet over the stacked raw wood, and sealing the circumference of the sheet; and then filling the sealed space enclosed by the sheet with gas for fumigation. If the raw wood has been transported in a shipping container or the like, the raw wood needs to be unloaded for the fumigation treatment. The reason for this is as follows. A common shipping container has corrugated side plates, and thus it is difficult to allow the gas for fumigation to fully spread within the interior of the shipping container. In addition, the extent to which the gas is spread and filled within the shipping container cannot be confirmed, making it difficult to stably carry out the fumigation operation. As described above, the necessity to unload the cargo significantly complicates the series of shipping operations, and makes it time-consuming as well as cost-consuming. 
     In contrast, when the shipping container according to the present invention is used, this fumigation operation can be carried out extremely smoothly and securely. In other words, although this shipping container does not have side plates, it is possible to easily seal the interior of the shipping container, by placing a sheet over the top plates  30  and covering the sides of the shipping container. In addition, by covering the shipping container by a sheet, it is possible to easily confirm the extent to which the gas for fumigation is spread and filled within the shipping container, and thus to adjust the amount of the gas to be introduced into the shipping container so that a uniform fumigation treatment can be performed. Further, if at least one of the columns  20  is in the shape of a ladder, an operator can climb up the ladder-shaped column  20  to the top of the shipping container, to smoothly carry out an operation for covering the shipping container with a sheet. 
     The above-described embodiment is merely an example, and the shape, the arrangement, the number and the like of the component members of the shipping container, such as the bottom plate  10 , the columns  20 , and the top plates  30  can be changed as appropriate, as long as it is possible to realize the object of the present invention, which is to provide a shipping container into which long objects such as lumber can be efficiently loaded. 
     DESCRIPTION OF SYMBOLS 
     
         
           10  bottom plate 
           11  front plate 
           12  openable and closable doors 
           13  fixing jig 
           14  wire 
           20  ( 20   a ) column 
           21  engaging wall 
           30  top plate 
           30   a ,  30   b  divided top plate portion 
           31  insertion recess 
           32  fitting recess 
           40  locking mechanism 
           41  first hook 
           41   a  first engaging protrusion 
           41   b  engaging recess 
           41   c  first biasing member 
           42  second hook 
           42   a  second engaging protrusion 
           42   b  abutment portion 
           42   c  second biasing member 
           43  unlocking bar 
           44  engaging piece 
           45  slit portion 
         C cargo 
         F forks