Abstract:
An automatic lock affixed to a cargo container for interconnecting two stacked containers, and for automatically locking and unlocking without reliance upon the overcoming of a friction force to release the device.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the interlocking of stacked cargo containers and, more particularly, to automatic locks which are secured to and travel with the container. 
     The prior art includes various devices for interconnecting stacked cargo containers. These devices include manual locks, semi-automatic locks, and automatic locks. As will be recognized to those skilled in the art, manual locking devices must be manually installed within the corner fitting, are manually locked, are manually unlocked, and are then manually removed from the corner fitting. Semi-automatic devices must be manually installed in the corner fitting, provide automatic locking but must be manually unlocked, and are then manually removed from the corner fitting. Finally, automatic devices must be manually installed in the corner fitting, provide automatically locking and unlocking, and are then manually removed from the corner fitting. 
     Although the art has advanced from manual locks to semi-automatic locks to automatic locks, and although each new design has provided certain additional benefits, today&#39;s fully automatic locks still have certain drawbacks. First, many prior art automatic locks still require an operator to manually install and remove the device from the corner fitting of the container, resulting in additional time and cost during loading/unloading. Second, many prior art automatic devices are designed to release once a predetermined friction force is overcome during hoisting of the container. Due to such factors as tolerances, wear and abuse of the corner fittings, designs which rely upon release of friction forces can provide inconsistent results. 
     There is therefore a need in the art for an automatic lock which is capable of interconnecting two stacked containers, and of locking and unlocking without reliance upon the overcoming of a friction force to release the device. The same automatic lock is preferably affixed to the container, thereby eliminating the need to install and remove such device during loading/unloading of the container. 
     SUMMARY OF THE INVENTION 
     The present invention, which address the needs of the prior art, provides an automatic lock for a cargo container. The container has an upper surface and a lower surface. The lower surface defines a plane P. The container further includes at least one lower corner fitting located on the lower surface thereof. The lock includes a corner fitting mechanism sized and configured for location within an opening formed in the lower corner fitting. The mechanism includes a lower cone sized and located to releasably engage an adjacent corner fitting when the container is stacked upon another cargo container. The lock further includes a rack having first and second ends. The first end of the rack is connected to the corner fitting mechanism whereby movement of the rack actuates the corner fitting mechanism to move the lower cone between a released unengaged position and a locked engaged position. The second end of the rack extends outward from the lower corner fitting. The lock further includes a first linkage having first and second ends. The first end of the first linkage is pivotably connected to the second end of the rack. The lock further includes a foot. The second end of the first linkage is pivotably connected to the foot. The lock further includes a second linkage having first and second ends. The first end of the second linkage is pivotably connected to the foot. The second linkage is spring-loaded. The lock further includes a mounting point affixed to the lower surface of the container. The second end of the second linkage pivotably connected to the mounting point. The first and second linkages are sized and located such that the foot is suspended below plane P prior to the stacking of the cargo container on another cargo container whereby the contact of the foot with the upper surface of another cargo container causes upward movement of the foot and the resultant movement of the first linkage and of the rack thereby resulting in the actuation of the corner fitting mechanism. 
     As a result, the present invention provides an automatic lock which is capable of interconnecting two stacked containers, and of locking and unlocking without reliance upon the overcoming of a friction force to release the device. This same automatic lock is preferably affixed to the container, thereby eliminating the need to install and remove such device during loading/unloading of the container. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a typical well car having two 53′ domestic cargo containers stacked thereon; 
         FIG. 2  is a schematical representation of the corner fittings of a domestic cargo container interacting with the retainers located on the floor of a well car; 
         FIG. 3  is a schematical end view of a well car showing two stacked domestic cargo containers; 
         FIG. 4  is a perspective view of a typical well car having a 53′ domestic cargo container stacked upon a 40′ ISO cargo container; 
         FIG. 5  is a schematical end view of a well car showing a domestic cargo container stacked upon an ISO cargo container; 
         FIG. 6  is a perspective view showing the automatic lock of the present invention; 
         FIG. 7  is a side elevation view showing an upper domestic cargo container incorporating the automatic lock of the present invention being landed upon a lower domestic cargo container; 
         FIG. 8  is a view similar to  FIG. 7  showing the upper domestic cargo container landed upon the lower domestic cargo container; 
         FIG. 9  is an enlarged detail of the automatic lock of  FIG. 6 , with the corner fitting removed for clarity; 
         FIG. 10  is a view taken along arrow A of  FIG. 6 ; 
         FIG. 11  is a view taken along arrow B of  FIG. 6 ; 
         FIG. 12  is a view showing the orientation of the components of the automatic lock of the present invention when the upper cargo container has been landed; 
         FIG. 13  is a view taken along arrow C of  FIG. 12 ; 
         FIG. 14  is a cross-sectional view taken along lines D-D of  FIG. 12 ; 
         FIG. 15  is a detail of the cam/cam follower arrangement of the automatic lock of the present invention; 
         FIG. 16  is a sectional view taken through the corner fitting mechanism of the automatic lock of the present invention; 
         FIG. 17  is a schematical top view of the cam/cam follower arrangement of the automatic lock of the present invention; 
         FIG. 18  is a flat pattern of the cam&#39;s profile and cam follower position, synchronized in time; 
         FIG. 19  is another sectional view taken through the corner fitting mechanism of the automatic lock of the present invention; and 
         FIG. 20  is a schematical view showing the interaction of one corner fitting of a domestic cargo container incorporating the automatic lock of the present invention with a retainer positioned on the floor of a well car. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is commonplace in the rail industry to use what are commonly referred to as well-cars (also known as double-stack cars) to transport cargo containers. A typical well-car  10  is shown in  FIG. 1 . A lower container  12  sits within the well of the car, while an upper container  14  rests upon lower container  12 . Those skilled in the art will recognize containers  12 ,  14  to be 53′ U.S. Domestic Containers, which is a common container used in the rail industry. These 53′ containers are all made with a standard size and configuration, including the location of four corner fittings on both the upper and lower surfaces. 
     Referring now to  FIG. 2 , each of containers  12 ,  14  is formed with a standard width of 8′-6″. As best seen in  FIG. 1 , the corner fittings are located at the outer edges of the container, such that the distance from the outer edge of corner fitting  16   a  to the outer edge of corner fitting  16   b  is also 8′-6″. Each of the corner fittings located on the lower surface of a domestic container is formed with both an outboard opening  18  and an inboard opening  20 . Located at the bottom of each well-car are four retainers  22 , which are sized and located to engage and penetrate the inboard openings of the four corner fittings located on the bottom surface of container  12  when container  12  is lowered into the well of car  10 . The combination of retainers  22  and the walls of the well-car ensure that container  12  is secure for transport. When a second container, e.g., container  14 , is to be stacked upon container  12 , it is industry practice today to use a plurality of twistlocks to interconnect and lock container  14  to container  12 . 
     The stacking of two 53′ domestic containers is best illustrated with reference to  FIG. 3 . As shown, retainers  22  affixed to the bottom of well car  10  penetrate inboard openings  20  in each of the four corner fittings located on the bottom surface of container  12 . The outboard openings  18  located in these same corner fittings are not used in this application. Four twistlocks  24  are then used to interconnect and lock container  14  to container  12 . 
     The rail industry also uses 8′ wide containers referred to as ISO standard containers. These ISO standard containers can be formed with lengths of 10′, 20′,  30 ′,  40 ′ and 49′. A 40′ ISO container  26  is shown in  FIG. 4 . As shown, container  26  is positioned within the well of car  10 . A 53′ domestic container  28  is stacked thereon. This stacked relationship is best illustrated with reference to  FIG. 5 . As illustrated in  FIG. 5 , container  26  includes a plurality of corner fittings  30 , all of which are formed with a single opening  32 . Openings  32  are located to engage retainers  22  in the same manner that openings  20  of fittings  16  engaged retainers  22 . A plurality of twistlocks  24  are used to interconnect and lock container  28  to container  26 . Inasmuch as container  26  is narrower in profile, inboard openings  20  of corner fittings  16  receive one of the locking cones of the twistlocks. In this application, outboard openings  18  of corner fittings  16  are not used. 
     It has been discovered herein that the dual opening configuration of the corner fittings on the lower surface of domestic containers can be utilized in the design of an automatic lock for such containers. More particularly, the present invention provides a novel automatic locking system which can be installed on the lower surface of a domestic container, and which will cooperate with the outboard opening of each corner fitting located on such lower surface. As will be explained further hereinbelow, such an arrangement still allows the domestic container to be used in the applications described above. More particularly, the novel arrangement of the present invention will not interfere with retainers  22  of well-car  10  engaging inboard openings  20  of corner fittings  16  when the domestic container is placed within the well of car  10 . In such a scenario, the novel locking arrangement of the present invention will simply remain unused. In the arrangement shown in  FIG. 5 , the novel locking arrangement of the present invention will also remain in unused condition without interfering with the usage of four twist locks to interconnect and lock container  28  to container  26 . However, in the common application shown in  FIG. 3  (wherein a domestic container is stacked upon another domestic container), the novel automatic locking arrangement of the present invention will eliminate the need for twistlocks  24 , thus saving time and money during loading and unloading of the containers. 
     An automatic lock  100  formed in accordance with the present invention is shown in  FIG. 6 . Lock  100  includes a corner fitting mechanism  102 , a rack  104 , a linkage  106 , a foot  108 , and a spring-loaded linkage  110 . As shown, mechanism  102  is located within outboard opening  112  of corner fitting  114 . The other end of automatic lock  100 , i.e., end  116  of linkage  110 , is pivotably connected to a mounting point  118  located on the bottom of the same container including corner fitting  114 . As will be more fully understood with reference to  FIG. 7 , mounting point  118  is located on the bottom surface of the container  120 , container  120  being a domestic container. Foot  108  extends downward below the plane, i.e., plane P, defined by the bottom surface of corner fitting  114 . As container  120  is lowered upon container  122  (also a domestic container), foot  108  contacts the upper surface  124  of container  122 . The continued lowering of container  120  causes foot  108  to move generally upward, which in turn moves linkage  106  and linkage  110 . More particularly, movement of linkage  106  causes horizontal movement of rack  104  (to the left as viewed in  FIG. 7 ). As shown in  FIG. 6 , rack  104  extends through a flange  126 , which restricts movement of rack  104  to a horizontal left and right translation (as viewed in  FIG. 7 ). The generally upward movement of foot  108  also causes spring-loaded linkage  110  to compress, thereby providing a biasing force tending to urge foot  108  downward to its “at-rest” position below the surface of plane P. 
       FIG. 8  shows domestic container  120  landed upon domestic container  122 . Foot  108  remains in contact with upper surface  124  of lower container  122 . As such, foot  108  has been moved toward the bottom surface of container  120 . This movement results in the translation of rack  104  to the left, which in turn causes lower cone  128  to move into its locking position within corner fitting  130  of container  122 . The movement of foot  108  also causes spring-loaded linkage  110  to compress into the biased position shown in  FIG. 8 . When upper container  120  is unloaded, the action is reversed—that is, spring-loaded linkage  110  moves foot  108  downward, which in turn moves linkage  106 , and ultimately rack  104  to the right (as viewed in  FIG. 8 ). It is further contemplated herein that foot  108  may be replaced with a spherical-shaped joint, which may be more resistant to inadvertent impact forces encountered during handling of the container. 
     To better illustrate the operation of mechanism  102 , corner fitting  114  has been removed from  FIG. 9 . Like  FIG. 8 ,  FIG. 9  shows lock  100  in its locked orientation. That is, foot  108  has been moved upward, spring-loaded linkage  110  has been moved into a biased position, and rack  104  has been translated to its left-most orientation. Lower cone  128  is shown in its rotated and locked orientation. In addition to lower cone  128 , corner fitting mechanism  102  includes a housing body  132 , a slider  134 , and a gear  136 . As shown in  FIG. 6 , housing body  132  preferably includes a front body portion  132   a  and a rear body portion  132   b . As will be more fully explained hereinbelow, the movement of rack  104  to the left causes rotation of gear  136 , which in turn causes vertical translation downward of slider  134 , as well as both vertical and rotational movements of lower cone  128 . Referring back now to  FIG. 8 , slider  134  is shown extended downward into corner fitting  130 , and lower cone  128  is rotated to engage at least a portion of corner fitting  130 . 
     In  FIG. 10 , rear body portion  132   b  has been removed for clarity. As shown, a spline shaft  138  extends through and engages gear  136 . As a result, rotation of gear  136  causes simultaneous rotation of shaft  138 . Shaft  138  is preferably an integral component which extends through gear  136  into engagement with lower cone  128  such that rotation of shaft  138  causes simultaneous rotation of lower cone  128 . A pair of cam followers  140   a ,  140   b  are secured to opposing sides of spline  138 , and follow cam surfaces  142   a ,  142   b  formed in body portions  132   a ,  132   b , respectively. As will be explained more fully hereinbelow, the lower edges of body portions  132   a ,  132   b  include skirts  144 . Skirts  144  extend around all four sides of mechanism  102 . 
     Referring back to  FIG. 7 , in one preferred embodiment mechanism  102  is configured such that lower cone  128  is located outside of corner fitting  114 , even when in the “at-rest” condition. This design recognizes the limited vertical height within corner fitting  114 , as well as the need to vertically displace lower cone  128  downward into engagement with the corner fitting on the container therebelow.  FIG. 11  (which is a view taken along arrow B of  FIG. 6 ) shows lower cone  128  in its “at-rest” position. This will also be the position of lower cone  128  when a container has been hoisted for loading. As mentioned hereinabove, lower cone  128  is connected to spline shaft  138 . Moreover, lower cone  128  translates vertically downward together with slider  134 . As a result, lower cone  128  is rotating at the same time it is being displaced downward. To ensure that lower cone  128  will be in a suitable orientation to allow passage through the opening in the corner fitting of the lower container, lower cone  128  is initially positioned in the orientation in  FIG. 11 . Thus, lower cone  128  can rotate through approximately 61 degrees from the initiation of translation to the point where lower cone  128  is within the corner fitting of the lower container. Once inside the corner fitting in the lower container, continued rotation of lower cone  128  will cause lower cone  128  to engage a portion of the corner fitting, thereby interconnecting the upper and lower containers. 
     Referring now to  FIG. 12 , mechanism  102  further includes a vertical spring  146 . Spring  146 , which functions to urge cam followers  140   a ,  140   b  into engagement with cam surfaces  142   a ,  142   b , will be described further hereinbelow. In one preferred embodiment, the vertical stroke of slider  134  is approximately 1⅜ inches. The orientation of lower cone  128  when in the fully rotated position is shown in  FIG. 13 . As mentioned hereinabove, lower cone  128  rotates through approximately 61 degrees of rotation as it translates downward to penetrate the corner fitting in the lower container. As shown, once inside the corner fitting of the lower container, lower cone  128  continues rotating counterclockwise (as viewed in  FIG. 13 ) approximately 15° such that bearing area  148  engages the corner fitting of the lower container. In one preferred embodiment, bearing area  148  provides the minimal bearing contact area of 400 mm 2 . Depending on the size and configuration of lower cone  128 , more or less rotation may be required to obtain the minimum bearing contact area. Is also contemplated herein that bearing area  148  may be configured to facilitate release of the lower cone from the lower corner fitting during unloading of the upper container. More particularly, bearing area  148  may be formed with a cross-sectional configuration which tends to rotate lower cone  128  in the clockwise direction (as viewed in  FIG. 13 ) in the event that hoisting of the upper container causes lower cone  128  to contact the inner surface of the lower corner fitting. 
     Cam surfaces  142   a ,  142   b  and cam followers  140   a ,  140   b  will be explained in greater detail with reference to  FIGS. 14-16 . Turning first to  FIG. 14 , cam followers  140   a ,  140   b  are rotatably connected to spline shaft  138  via shafts  150   a ,  150   b , respectively. As best seen in  FIG. 15 , as spline shaft  138  rotates clockwise, cam follower  140   b  will travel along cam surface  142   b . Simultaneously, cam follower  140   a  will travel along cam surface  142   a . Referring now to  FIG. 16 , one end of vertical spring  146  extends within spline shaft  138 , while the other end extends upward to contact the interior floor of the upper container. More particularly, spring  146  is arranged to contact a fixed surface of the upper cargo container such that spring  146  maintains a downward biasing force against shaft  138 . This downward biasing force will ensure that the cam followers remain in contact with the cam surfaces as spline shaft  138  is rotated. As best seen in  FIG. 16 , shaft  138  includes a shoulder  152 . Slider  134  is accordingly captured between shoulder  152  and lower cone  128 . As a result, vertical displacement of spline shaft  138  causes simultaneous vertical displacement of slider  134 . Spline shaft  138  is also free to rotate with respect to slider  134  as it is vertically displaced. Due to the size limitations of the corner fitting, a portion of spline shaft  138  preferably extends above the height of gear  136  (see  FIG. 10 ), such portion extending into opening  154  of the corner fitting shown in  FIG. 16 . As a result, vertical spring  146  is preselected to have a length which extends through this same opening and contacts interior floor  156  of the container. Of course, is contemplated herein that vertical spring  146  could be configured to contact another fixed area of the corner fitting and/or upper cargo container. 
       FIGS. 17-18  provide further details regarding the cam/cam follower arrangement of the present invention.  FIG. 17  provides a schematical cross-sectional view showing the connection of the cam followers to the spline shaft, as well as the front and rear cam surfaces.  FIG. 18  is a flat pattern of the cam&#39;s profile, together with the cam follower position, synchronized in time. The front and rear patterns are substantially identical. At 0° (i.e., the initial position), the slider is an upper position. Vertical spring  146  is fully compressed between interior floor  156  and the contact surface within the spline shaft. The force exerted by spring  146  forces each of the cam followers into contact with their respective cam surfaces. At this point, foot  108  begins to contact a surface therebelow, e.g., the upper surface of a lower domestic container. From 0° to 5°, the upper domestic container is lowered downward. This in turn causes generally upward displacement of foot  108 , which in turn causes movement of the rack (to the left is viewed in  FIG. 12 ), and in turn rotation of gear  136 . During this first 5° of rotation, downward translation of slider  134  is preferably restricted. The restriction of downward movement of slider  134  during this first 5° of rotation limits/eliminates unwanted movement of the cam followers due to vibrations/forces encountered at the initiation of landing, e.g., forces generated by the initial compression of spring-loaded linkage  110 . From 5° to an angle β=61°, the slider moves down, and the lower cone rotates in the clockwise direction (as viewed from above). Once angle β has been reached, lower cone  128  has penetrated the opening in the lower corner fitting and is positioned for locking rotation. During the same time, foot  108  has been translated upward, and spring-loaded linkage  110  has been compressed. The 61° angle mentioned above corresponds to the 61° angle discussed with reference to  FIG. 11 . Depending on the configuration and design, this 61° angle may be increased or decreased. From angle β to 97°, the landing of the upper cargo container continues. During this time, the slider is in its lowest position, and lower cone  128  continues to rotate. From 97° to 120°, the lower cone rotates to its locked position, i.e., to provide the required bearing surface contact area. At 120°, the landing of the upper cargo container has been accomplished. 
     Referring now to  FIG. 19 , and as mentioned hereinabove, body  132  is formed with a plurality of skirts  144  about its lower edges (see  FIG. 10 ). Skirts  144  interact with chamfered edges  158  of the opening in the corner fitting. As such, mechanism  102  can be inserted into the opening until skirts  144  contact chamfered edges  158 . It will be appreciated that this contact occurs on all four sides of mechanism  102 , thus limiting any movement of mechanism  102  with respect to the corner fitting, other than downward vertical movement. To secure mechanism  102  within the corner fitting, a plurality of wedges  160  are employed. As shown, two wedges are attached on each side of mechanism  102  via clamping screws  162 . Wedges  160  are preferably formed with a conical shape such that tightening of screw  162  forces the individual wedge into greater contact with the interior surface of the corner fitting, thus urging mechanism  102  vertically upward, while at the same time fixedly securing mechanism  102  therein. 
       FIG. 20  shows a corner fitting of a domestic container containing the automatic lock of the present invention interacting with a retainer positioned on the floor of a well-car. As discussed hereinabove, the retainers located on the floor of the well-car penetrate and engage the inboard openings of the lower corner fittings. Plate  164 , which supports retainer  22 , typically has a thickness of approximately ½ inch. In one preferred embodiment, lower cone  128  is designed to extend approximately ½ inch below the surface of the corner fitting. As a result, the cargo container will rest upon plates  164 , and not upon lower cone  128 . 
     It is contemplated herein that a domestic container containing the automatic lock of the present invention may be landed on the ground. In this situation, the weight of the container will rest upon the four lower cones protruding from the lower corner fittings. The novel design of the current automatic lock ensures that the mechanism fitted within each corner fitting can support the weight of the container. In addition to the domestic containers described hereinabove, it is contemplated herein that the automatic lock of the present invention may be utilized with other standard containers used in the different forms of cargo transportation. 
     It will be appreciated that the present invention has been described herein with reference to certain preferred or exemplary embodiments. The preferred or exemplary embodiments described herein may be modified, changed, added to or deviated from without departing from the intent, spirit and scope of the present invention, and it is intended that all such additions, modifications, amendments and/or deviations be included in the scope of the present invention.