Patent Publication Number: US-8991780-B2

Title: Shock absorbing system for load carrier

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage application of International Application No. PCT/NO2011/000049, filed Feb. 8, 2011, which International application was published on Aug. 18, 2011 as International Publication No. WO 2011/099867 A1 in the English language and which application is incorporated herein by reference. The International application claims priority of Norwegian Patent Application No. 20100201, filed Feb. 9, 2010, which application is incorporated herein by reference. 
     BACKGROUND 
     The invention relates to a device for a load carrier provided with a support structure and means arranged for connection to a lifting medium, and more particularly in that the support structure comprises one or more shock absorbers provided with a telescoping element, which in an initial position projects downward from an underside of the support structure and is arranged for damped compressive telescoping at the contact of the load carrier with a base. 
     Load carriers, such as cargo containers, being used for transport of goods between shore and installations offshore, for example exploration or production platforms in a hydro-carbon field offshore, are often exposed to very large strains when they are moved by means of lifting cranes between a transport vessel and the installation while the ship and possibly also the installation are subjected to wave induced motions. Even if the lifting equipment is provided with heave compensators, the load carrier will often be exposed to heavy impacts when hitting the deck surface of the vessel, and such impacts often inflict extensive damage to cargo and interiors. Special containers such as containers fitted out as store rooms having shelving and other rigidly mounted equipment have an average useful life, at the worst of down to two transport rounds, i.e. two return trips to/from a shore base/installation. 
     Correspondingly other transfer situations may provide the same problem. The problems are thus not only tied to transfer of load carriers between ships and installations in an oil-field offshore. 
     The problem is in prior art sought solved by the equipment to be protected being provided with shock absorbing means, for example elastic suspension for attachment to the load carrier. This is costly and often renders limitations in the functionality of the equipment. 
     SUMMARY 
     The object of the invention is to remedy or reduce at least one of the disadvantages of the prior art, or at least to provide a useful alternative to the prior art. 
     The object is achieved by the features disclosed in the below description and in the subsequent claims. 
     In the further description the term “load carrier” is used for closable containers (containers having closed sides and top and having one or more side gates), open container (open top or one or more open sides), cargo pallets and cargo frames with or without beams defining the cargo volume. Common for all types of “load carrier” is that they are provided with a support structure that the cargo is resting on, and that the support structure is provided with hoisting attachments for releasable connection to a cargo crane. The “load carrier” may be provided with support surfaces for bearing against a lifting fork, often arranged as so-called fork pockets provided as horizontal passages in the support structure. 
     The invention provides in its simplest form a load carrier provided with several telescoping shock absorbers, which in their extended positions project downward from the support structure underside and are arranged to be able to abut supportingly a supporting base, such as a deck. The telescoping element of the shock absorber is, when the load carrier is not in contact with the base, arranged to be displaced to its maximum extended position, preferably by the weight of own or connected elements, alternatively assisted by one or more actuators. 
     The telescoping element of the shock absorber is alternatively connected to a sub-frame arranged under the support structure and arranged to be able to abut the supporting basis supportingly. The shock absorbers render a vertical displacement of the sub-frame relative to the support structure possible. 
     The telescoping element of the shock absorber exhibits a large degree of stability against sideways displacement as side guides are incorporated in the shock absorbers. Alternatively side guides, preventing a horizontal displacement of the sub-frame relative to the support structure when side loading is applied to the load carrier, are arranged between the sub-frame and the support structure. 
     The damping function of the shock absorbers is preferably active when the telescoping element in the shock absorber is displaced in a direction toward the main frame. 
     The shock absorbers may be incorporated in a vertical framework bounding the load carrier and possibly forming a connection between the support structure and hoisting attachments arranged in an upper portion of the load carrier. 
     Between the main frame and the sub-frame there may be arranged one or more actuators arranged to apply a pushing force on the sub-frame directed away from the support structure. The actuator may expediently be incorporated in one or more of the shock absorbers. 
     The invention relates more specifically to a shock absorbing device for a load carrier provided with a support structure and means arranged for connection to a lifting means, characterized in that the support structure comprises one or more shock absorbers provided with a telescoping element, which in an initial position projects downward from an underside of the support structure and is arranged for damped compressive telescoping at the load carrier contacting a basis. 
     A sub-frame arranged to abut the base supportingly, may be arranged vertically displaceable under the support frame and be connected to the telescoping element of the shock absorbers. This renders a shock absorbing action at blows against any portion of the load carrier&#39;s lower portion. 
     The shock absorbers may be single acting. The shock absorbing function will thereby to a small degree affect the displacement of the shock absorbers back to an initial position. 
     The telescoping element of the shock absorber may be arranged to be able to be displaced to an outward projecting initial position by means of its own weight or that of connected elements, an actuator or a combination of these. There is thereby provided a series of means securing that the shock absorbers take up a correct initial position as soon as the load carrier is lifted clear of the basis. 
     The shock absorbers may be provided with or be connected to side stabilizing means. The shock absorbers may thereby on their own resist side loading at the load carrier hitting the basis. There may, connected to the sub-frame and the support structure, be arranged side guides preventing a horizontal displacement of the sub-frame relative to the support structure when a side load is applied to the load carrier. This renders the use of a wider spectrum of shock absorbers possible, and the sideways stability is easier to adapt to the needs. 
     The sub-frame may be provided with one or more side guiding elements in sliding contact with corresponding side guides in the support structure. The sideways stability is thereby upheld with simple means. 
     The shock absorbers may be incorporated in a vertical framework bounding the load carrier and forming a connection between the support structure and hoisting attachments arranged in an upper portion of the load carrier. The shock absorbers thereby do not take up much floor space on the load carrier. 
     The sub-frame may be provided with means arranged to cover the openings between the sub-frame and the support structure. This reduces the risk for injury to personnel and damage to equipment. 
     There may, from the sub-frame project upwards cover plates encircling at least a lower portion of the supporting structure. The covering of the openings between the sub-frame and the support structure may thereby be made with simple means standing up to heavy blows. 
     The invention more particularly concerns a load carrier device provided with a support structure and means arranged for connection to a lifting means and the support structure comprises one or more shock absorbers provided with a telescoping element which in an initial position projects downward from an underside of the support structure; wherein
         the shock absorber is arranged for damped compressive telescoping at the contact of the load carrier with a base, as the telescoping element in a fluid sealing manner is led through an end wall in a cylindrical, liquid filled shock absorber housing and is connected to a displaceable piston arranged in the shock absorber housing; and   the shock absorber comprises means arranged for single acting damping of the telescoping element in the compressive telescoping direction, the piston or a fluid circuit connecting a piston side and a piston rod side in the shock absorber housing being provided with a flow valve arranged to choke a liquid flow from the piston side to the piston rod side, the flow in the opposite direction being approximately free.       

     A sub-frame arranged to abut supportingly against the basis, may be arranged vertically displaceable under the support structure being connected to the telescoping element of the shock absorbers. 
     The telescoping element of the shock absorbers may be arranged to be able to be displaced to an outwards projecting initial position by means of its own weight or that of its attached elements, an actuator or a combination of these. 
     A piston&#39;s and the telescoping element&#39;s guidance in the shock absorber housing and the end wall may provide sideways stabilization of the shock absorber. 
     The shock absorbers may be connected to a sub-frame by means of shock absorbing anchors providing sideways stabilization of the shock absorber. 
     Side guides may be connected to the sub-frame and the support structure, the side guides being arranged to prevent a horizontal displacement of the sub-frame relative to the support structure when a sideways load is applied to the load carrier. 
     The sub-frame may be provided with one or more side guiding elements in slidable engagement with corresponding side guiding guides in the support structure. 
     The shock absorbers may be integrated in a vertical framework bounding the load carrier and forming a connection between the support structure and hoisting attachments arranged in an upper portion of the load carrier. 
     The sub-frame may be provided with means arranged to cover the openings between the sub-frame and the support structure. 
     From the sub-frame there may project upwards cover plates encircling at least a lower portion of the support structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein: 
         FIG. 1  shows a side view of a load carrier hanging above a deck with telescopic shock absorber elements pushed out from the underside of a support structure; 
         FIG. 2  shows a side view of a load carrier hanging above a deck with sub-frame connected to shock absorbers and displaced away from the main frame of the support structure; 
         FIG. 3  shows the load carrier resting on the deck, as the sub-frame is led to abutment against the main frame; 
         FIG. 4  shows in a side view a hanging, enclosed load carrier with the sub-frame displaced away from the main frame, and the main frame provided with cover plates arranged to prevent foreign objects being crushed between the main frame and the sub-frame. 
         FIG. 5  shows certain telescopic shock absorber elements depicted in  FIG. 1  in larger scale. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     In the figures the reference numeral  1  indicates a load carrier. In the  FIGS. 1 ,  2  and  3  it is shown as an open cargo frame, and in  FIG. 4  it is schematically shown as an enclosed container. The load carrier  1  is displaced with a lifting means  2 , such as a lifting crane, connected to hoisting attachments  131  arranged in a top frame  13 . The load carrier  1  is expediently also configured with fork pockets  113  in a support structure  11  for placing of loading forks on a fork truck (not shown). 
     The load carrier  1  is arranged to rest on a supporting basis  3 , such as a deck on a vessel (not shown) or a floor. The reference numeral  4  indicates schematically a load arranged on the load carrier  1 . 
     The support structure  11  forms a basis for the load  4 , possibly shaped as a floor. In the corner portions of the support structure  11  are arranged shock absorber attachments  112 , shown here as an integrated part of upward projecting side frames  12 . 
     The side frames  12  are in their upper portions joined to a top frame  13  provided with multiple hoisting attachments  131 . 
     To each of the shock absorber attachments  112  is fastened a telescopic shock absorber  15  comprising a cylindrical, liquid filled shock absorber housing  151  containing a displaceable piston  152  provided with a telescoping element in the form of a shock absorber stay  153 , which in a fluid sealing way is led through a lower end wall  155 . The piston  152  is provided with a flow valve  154  arranged to choke a liquid flow through the piston  152  in a direction from the over- to the underside, while the flow in the opposite direction is approximately free. 
     In a first embodiment example according to  FIG. 1  the shock absorber stay  153  projects in an initial position out from the end wall  155  lying in essentially the same plane as the underside  114  of the support structure  11 . To ensure that the shock absorber stay  153  is displaced to its outward projecting initial position when the load carrier is lifted clear of the base  3 , there is to the piston  152  connected an actuator  16 , shown schematically here as a spring arranged to apply a pushing force to the piston  152  sufficient to displace it to its initial position abutting the end wall functioning as an end stop. During this displacement the fluid contained in the shock absorber housing  151  flows approximately freely through the flow valve  154  from the underside of the piston  152  to its overside. The shock absorber stay  153  is stable sideways, i.e. it resists sideways movement when sideways forces are applied. This is provided by the shock absorber  15  being rigidly attached to the load carrier  1 , and the piston  152  and the shock absorber stay  153  being guided by the shock absorber housing  151  and the end wall  155  respectively. 
     In a second embodiment example, see particularly  FIGS. 2 and 3 , there is arranged a sub-frame  14  under the support structure  11 . The sub-frame  14  has a horizontal extension essentially identical to the support structure  11 . The shock absorber stay  153  is attached to the sub-frame  14  in shock absorber anchors  142 . Sideways guiding elements  143  projecting upward extend into side guides  111  in the support structure  11  shaped like corresponding recesses that are closed towards the overside of the support structure  11 . 
     In this embodiment example the sub-frame  14  apply a sufficient load on the shock absorber stays  153  for them to be displaced to their outward projecting initial position when the load carrier  1  is lifted clear of the base  3 . In this embodiment the shock absorbers  15  may be pivotably attached to the support structure  11  and the sub-frame  14 , as the sideways guiding is taken care of by the sideways guiding elements  143  and the corresponding side guides  111 . 
     In  FIG. 4  is shown an embodiment example where the sub-frame  14  is provided with cover plates  144  projecting upward and encircling the support structure  11  excepting recesses  145  arranged at the fork pockets  113 . 
     When the load carrier  1  is lifted clear of a base  3 , the shock absorbers  15  are displaced to their extended initial positions. In the embodiment examples with a sub-frame  14  it is displaced away from the support structure  11 . As the load carrier  1  is lowered again toward a base  3 , the first touch will be between one or more shock absorber stays  153 , possibly a portion of the sub-frame  14 , and any shocks are dampened by the shock absorbers  15 , which, during the continued lowering of the load carrier  1  toward the base  3 , are telescopically shortened with resistance caused by the flow resistance in the choking of the flow valve  154 . 
     In the embodiment example shown in  FIG. 4  the cover plates  144  provides for foreign bodies not being able to come inside and be crushed between the support structure  11  and the sub-frame  14 .