Patent Publication Number: US-2022219961-A1

Title: Industrial truck

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/056652, filed on Mar. 12, 2020 and which claims benefit to German Patent Application No. 10 2019 112 580.4, filed on May 14, 2019. The International Application was published in German on Nov. 19, 2020 as WO 2020/229019 A1 under PCT Article 21(2). 
    
    
     FIELD 
     The present invention relates to an industrial truck comprising opposing masts for lifting and lowering a loading platform which is located between the masts in a lifting and lowering direction. 
     The present invention in particular relates to an industrial truck which is used to transport air freight shipment pallets or containers. 
     BACKGROUND 
     An industrial truck of this type has previously been described under the name “Xway Mover 7000” from DIMOS Maschinenbau GmbH. In this industrial truck, four masts are described for lifting and lowering, each of which is equipped with a hydraulic cylinder. Hydraulic fluid is applied to each hydraulic cylinder independently from each other. 
     The disadvantage of this vehicle is that it is expensive to manufacture and that the maximum achievable lift heights cannot or can only be adapted to various requirements with a high constructive effort. 
     SUMMARY 
     An aspect of the present invention is to provide an industrial truck which is improved in this regard. 
     In an embodiment, the present invention provides an industrial truck which includes a loading platform and two masts which are arranged opposed to each other. The two masts are configured to lift and to lower the loading platform which is arranged between the two masts in a lifting and lowering direction. Each of the two masts comprises two pulleys which are arranged spaced apart in the lifting and lowering direction, a flexible pulling device which is configured to revolve around each of the two pulleys, and a drive device which is configured to rotationally drive at least one of the two pulleys. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described in greater detail below on the basis of embodiments and of the drawings in which: 
         FIG. 1  is a first perspective view of an embodiment of an industrial truck according to the present invention; 
         FIG. 2  is a second perspective view of the same embodiment; 
         FIG. 3  is a side view of the same embodiment; 
         FIG. 4  is a view corresponding to  FIG. 2  of the same embodiment, but loaded with a transport container; 
         FIG. 5  is a view from below of the same embodiment; 
         FIG. 6  is a view from above of the same embodiment; 
         FIG. 7  is a partial view of the same embodiment in a view according to  FIG. 1  from the rear; 
         FIG. 8  is a perspective rear view of a first embodiment of one of the two masts of the industrial truck according to the present invention; 
         FIG. 9  is a perspective front view of the mast shown in  FIG. 8 ; 
         FIG. 10  is a front view of the front side of the same mast; 
         FIG. 11  is a view of the same mast from above; 
         FIG. 12  is a detailed view of a drive device of this mast; 
         FIG. 13  shows a machine element which is driven in rotation via the drive device and which interacts with a flexible pulling device; 
         FIG. 14  is a perspective rear view of a second embodiment of a mast; 
         FIG. 15  is a plan view of the front side of the same mast; 
         FIG. 16  is a perspective front view of the same mast; 
         FIG. 17  is a perspective detail view of the upper region of a mast, and 
         FIG. 18  is a detail view of the central region of the embodiment of the mast shown in  FIGS. 14 to 16 . 
     
    
    
     DETAILED DESCRIPTION 
     In the industrial truck according to the present invention, each of the masts comprises two pulleys which are spaced apart in the lifting and lowering direction and around which a flexible pulling device revolves, at least one of the pulleys being rotationally driven by a drive device. This arrangement replaces at least one of the lifting cylinders provided in the vehicle as described in the prior art. The industrial truck according to the present invention can be produced significantly more cost-effectively. The drive device can, for example, also comprise an electric motor so that complex piping and hydraulic pumps can be completely dispensed with, which further reduces the manufacturing cost of the industrial truck according to the present invention. 
     The pulleys, which are spaced apart from one another, can, for example, be arranged so that the flexible pulling device comprises two strands extending in the lifting and lowering directions. The loading platform must then only be mechanically connected to one of the strands for lifting and lowering. 
     The loading platform can, for example, be connected to two parallel strands of the flexible pulling device of the two masts. The load which the industrial truck according to the present invention is suitable for lifting can thereby be increased. This measure also increases the operational safety of the industrial truck according to the present invention since, in the event of a failure of one of the two flexible pulling devices, for example, by being torn off, an uncontrolled lowering of the loading platform can be prevented. 
     A further development of the industrial truck according to the present invention provides that at least one of the lower pulleys of the two masts can, for example, be non-rotatably connected to the drive shaft of a drive device and the two lower pulleys of the two masts can, for example, be mechanically connected to one another via a connecting shaft. A synchronization of the two flexible pulling devices of the two masts is thereby provided. It is thereby also possible to in principle only provide a single drive device. 
     However, both lower pulleys of the two masts to the drive shaft of a separate drive device can, for example, be non-rotatably connected. This allows the achievable lifting capacity to be increased and increases the operational safety of the industrial truck according to the present invention since, even if a drive device fails, the loading platform can be raised and lowered, albeit with reduced power. 
     In a further development of the industrial truck according to the present invention, at least one of the two pulleys of each mast can, for example, be mounted in a bearing block which is arranged in a bearing block receptacle of the corresponding mast so that it can be moved in a tensioning direction. The tension of the flexible pulling device that is required for a trouble-free operation can thereby be set in a simple manner. It is thereby also easily possible to, if necessary, relax the flexible pulling device which may, for example, be necessary for an exchange. 
     The flexible pulling means can be designed in a variety of ways, for example, as a chain, a toothed belt, a ribbed belt, a V-belt, etc. The pulleys are adapted to the corresponding design of the flexible pulling device. 
     In an embodiment of the industrial truck according to the present invention, each flexible pulling device can, for example, have two parallel V-belts, and the pulleys are accordingly designed as double belt pulleys. The use of two parallel V-belts again increases the operational safety of the industrial truck according to the present invention. 
     In an additional further development of the industrial truck according to the present invention, each of the masts can, for example, comprise a first main frame, to which at least one second main frame can optionally be attached. In other words, in this development, the masts are of modular design, each module comprising a main frame. Only a main frame must be added to change the length of the mast and the associated change in the maximum achievable lifting height. One of the main frames must be removed if a plurality of main frames are already connected to one another and the length of the mast is to be reduced. The previously used flexible pulling device must be replaced by one with an adapted length. This development of the industrial truck according to the present invention makes it possible to subsequently also easily adapt industrial trucks delivered with a specific, maximum lifting height to requirements that have changed with regard to the desired lifting height. 
     The attachability of a second main frame to a first main frame is particularly simple if the first main frame has, for example, an upper cross strut and the lower main frame has a lower cross strut, the lower cross strut being designed to be attachable to the upper cross strut. 
     In an embodiment, the industrial truck according to the present invention can, for example, comprise steering motors and travel drives which are also designed to be electrically operated. This development of the industrial truck according to the present invention is again characterized by a particularly low manufacturing cost since the operation of the vehicle is only possible from a single energy source, i.e., an electrical power storage device. 
     The present invention will be explained in greater detail below under reference to the drawings. 
     The embodiment of an industrial truck according to the present invention (hereinafter “industrial truck  100 ” for short) shown in the drawing comprises a chassis  1  with a loading region  2  which is delimited by side regions  3 ,  4 . In the two side regions  3  and  4 , components (which are not recognizable in the drawing) are accommodated that are required in the operation of the industrial truck, for example, energy storage devices such as fuel tanks and accumulators, drive devices for driving and lifting functions, electrical and hydraulic circuits for regulating or controlling the drive and lifting operations as well as for steering the industrial truck, etc. 
     In  FIG. 1 , the forward and reverse directions of travel F, R are symbolized by the arrows F, R. 
     A driver&#39;s cab  5  is arranged in the front region of the left-hand side region  4  as seen in the forward direction of travel F. The driver&#39;s cab  5  comprises the actuation devices required to operate the industrial truck  100 , such as buttons, switches, joysticks, and a steering wheel. 
     As can in particular be seen in  FIG. 5 , the industrial truck  100  has four wheels, the front wheels  6  assigned to the front axle A being designed as twin wheels and the rear wheels  7  assigned to the rear axle B being designed as individual wheels. All of the four wheels are designed to be steerable so that they can be rotated through 360° about their corresponding steering axle S. Each of the wheels  6 ,  7  is connected to its own steering motor (which is not shown in the drawings). All steering motors can, for example, be designed as electric motors and be controlled via a steering computer so that the industrial truck  100  can change the direction of travel in any sequence without stopping. A loading or unloading station can thus be approached directly without complex maneuvering. 
     At least one of the front wheels  6  and rear wheels  7  is coupled to a travel drive. In order to improve traction, all front wheels  6  and rear wheels  7  can, for example, each be coupled to a travel drive. The travel drive(s) can, like the steering motors, comprise electric motors. 
     As can be seen in  FIG. 5 , the chassis  1  has two cross members  8  which extend parallel to one another and which are arranged between the front axle A and the rear axle B. The two cross members  8  connect the side regions  3  and  4 . The cross members  8  are arranged close to the ground and have a comparatively low overall height Y compared to the transverse extension X, so that only a low loading and unloading height H can be achieved with the industrial truck  100 , as will be explained in more detail below. 
     Two masts  9 ,  10  extend upward from the chassis  1 . The facing sides of the two masts  9 ,  10  are arranged at least almost flush with sides of the side regions  3 ,  4  facing one another. 
     The two masts  9 ,  10  are used to raise and lower a loading platform  11  in a lifting and lowering direction Z. It is used to carry a load, for example, a container C. For this purpose, each mast  9 ,  10  has a flexible pulling device  12  which revolves around a lower pulley  13  and an upper pulley  14 . In the illustrated embodiment, the flexible pulling device  12  comprises two V-belts running parallel to one another. They are stretched between the lower and upper pulleys  13 ,  14 , which are designed as double belt pulleys. While the upper pulley  14  is mounted in a bearing block  15  which is stationary so as to be freely rotatable about an axis  16 , the lower pulley  13  is non-rotatably connected to the drive shaft  17  of a drive device  18 . The drive device  18  can, for example, also comprise an electric motor. 
     The drive device  18  is mounted on a bearing block  19  which is arranged displaceably on the mast  9 ,  10  for the purpose of adjusting the tension of the flexible pulling device  12  (see in particular  FIGS. 12 and 13 ). For this purpose, the masts  9 ,  10  each have a bearing block receptacle  20  which is larger in the tensioning direction T than the bearing block  19 . According to  FIGS. 12 and 13  from above, two threaded bores open into the bearing block receptacle  20 , into each of which a clamping screw  21  is screwed. The front end of each of the clamping screws  21  in the screwing-in direction is supported on a surface of the bearing block  19 . As is evident from  FIGS. 12 and 13 , the tension of the flexible pulling device  12  can be changed by turning the clamping screws  21  in and out. 
     The flexible pulling device  12  has two strands  22 ,  23  which run parallel to one another due to their revolving around the lower and upper pulleys  13 ,  14 . The drive shafts  17  of the two drive devices  18  of the masts  9 ,  10  can, for example, be mechanically connected to one another via a connecting shaft  24  so that the flexible pulling device  12  of the two masts  9 ,  10  revolve at exactly the same speed (see  FIG. 5 ). By providing a connecting shaft  24 , it is basically also possible to provide only a single drive motor as the drive device  18  for the flexible pulling device  12  of the two masts  9 ,  10 . 
     For the purpose of lifting and lowering, the loading platform  11  is connected to one of the two strands  22 ,  23  of the two flexible pulling devices  12  of the masts  9 ,  10 , which strands run in the same direction when the drive devices  18  are actuated, for example, in each case to strand  23 . 
     Guide profiles  25 ,  26  are provided on the masts  9 ,  10  to guide the loading platform  11  on the masts  9 ,  10 , as can be seen in particular in  FIGS. 10 and 11  using the example of mast  9 . Each guide profile  25 ,  26  has an internal cross section which is designed to be approximately C-shaped. It has a base surface  27  and two mutually parallel side surfaces  28 ,  29  extending perpendicularly from the base surface  27  to the open profile side  30 . 
     The guide profiles  25 ,  26  are arranged on the corresponding mast  9 ,  10  so that their open profile sides  30  face one another. 
     As can be seen in  FIG. 11 , the loading platform  11  has two guide rollers  31 ,  32  on its side facing the mast  9 , which guide rollers  31 ,  32  in the illustrated embodiment each roll on one of the two outer side surfaces  29  of the guide profiles  25 ,  26  and thus guide the loading platform  11  to prevent displacements relative to the mast  9  in the F-R direction of the industrial truck  100 . The loading platform  11  can of course also be designed to correspond to the side facing the other mast  10  (not shown in  FIG. 11 ). The mast  10  also has guide profiles  25 ,  26 . It should finally be pointed out that the guide rollers  31 ,  32  can also be arranged so that they both roll on the central side surfaces  28  of the guide profiles  25 ,  26 . Further guide rollers (not shown in the drawing) can also be provided offset in the longitudinal direction of the guide profiles  25 ,  26  relative to the guide rollers  31 ,  32 , which further guide rollers in turn roll on one of the side surfaces  28  or  29 . The loading platform can as a result also be secured against tilting in an axis running perpendicular to the plane of the drawing in  FIG. 10  with the aid of the guide profiles  25 ,  26 . 
     A major advantage of the design and arrangement of the guide profiles  25 ,  26  and the guide rollers  31 ,  32  rolling therein is that forces acting on the loading platform  11  in the F-R direction, as can occur in particular during loading and unloading, are directly absorbed by the two masts  9 ,  10 , and no further, possibly technically complex measures are required therefor. 
     As already mentioned above, the industrial truck  100  has a particularly low loading and unloading height H. As can be seen in  FIG. 7 , this is substantially identical on the front axle side and the rear axle side. This is caused by the design of the chassis  1  with the cross members  8  in contrast to the known U-shaped design of the chassis with a single, rear cross member  8 , which must be designed considerably more voluminous in cross section than the two cross members  8  which are spaced apart in the longitudinal extension in order to achieve the required chassis rigidity of the industrial truck  100 . In order to be able to minimize the loading and unloading height H, the loading platform  11  has recesses  33  on the underside for one of the cross members  8 , so that the loading and unloading height H only slightly exceeds the vertical extension of the cross members  8  from the ground. 
     Each of the cross members  8  can comprise two struts  34 ,  35  which run parallel to one another and have a rectangular, for example, a square cross section. The struts  34 ,  35  are connected to one another via a connecting plate  36 . 
     As can be seen, for example, in  FIGS. 8 and 9 , the masts  9 ,  10  each have a base plate  37  from which a lower frame component  38 , which comprises the bearing block receptacle  20 , extends upward. The lower frame component  38  is approximately designed so as to be U-shaped when viewed from the front or the rear of the mast  9 ,  10 . Side walls  39 ,  40  of the mast, which are provided with lateral stiffening ribs  41 ,  42 , rest on the outer sides of its two legs. A first main frame  43 , which comprises lateral profiles  44 ,  45  connected to one another via cross struts  46 ,  47 ,  48 , extends upward from the base plate  37 . Diagonal strutting  49 ,  50  arranged in an X like manner extend between the lower cross strut  46  and the central cross strut  47 . The guide profiles  25 ,  26  are fastened to the base plate  37 , the side walls  39 ,  40 , and the cross struts  46 ,  47 ,  48 . The so constructed mast is characterized by considerable torsional rigidity combined with low weight and low manufacturing costs. 
     In the embodiment of the mast shown in  FIGS. 8, 9 and 10 , the upper bearing block  15  is arranged between the central cross strut  47  and the upper cross strut  48 . As can be seen by comparison with the further embodiment of a mast  9 ,  10  shown in  FIGS. 14 to 18 , the bearing block  15  between the cross struts  47  and  48  is missing in this further embodiment. A further main frame  51  instead extends upward from the upper cross strut  48 . It has a lower cross strut  52  which is screwed to the upper cross strut  48  of the first main frame  43 . A central cross strut  55  is connected to the lower cross strut  52  via diagonal strutting  53 ,  54 . The bearing block  15  is arranged between this and an upper cross strut  56 . The guide profiles  25 ,  26  extend from the base plate  37  to the upper cross strut  56 ; the guide profiles  25 ,  26  are, for example, designed in the mast shown in  FIGS. 14 to 18  so as to be longer by adding guide profile portions  57  compared to the guide profiles shown in  FIGS. 8 to 10 . The flexible pulling device  12  accordingly also has a greater length in the embodiments shown in  FIGS. 14 to 18  than in those shown in  FIGS. 8 to 10 . 
     From the above explanations, it can be seen that, due to the modular construction of the mast with a variable number of diagonal strutting and cross struts, it is possible to easily provide masts of different lengths that are adapted to user requirements. It can further be seen that, due to this modular structure, already existing industrial trucks comprising corresponding masts can be adapted to changing requirements with only little effort in terms of the maximum lifting height that can be achieved therewith. For this purpose, only segments, as denoted by D in  FIG. 15 , together with the associated guide profile portions  57  of the corresponding mast  9 ,  10  must be removed or supplemented, and the flexible pulling device  12  must be replaced by one of suitable length. 
     The present invention is not limited to embodiments described herein; reference should be had to the appended claims. 
     LIST OF REFERENCE NUMERALS 
     
         
         
           
               100  Industrial truck 
               1  Chassis 
               2  Loading region 
               3  Side region 
               4  Side region 
               5  Driver&#39;s cab 
               6  Front wheels 
               7  Rear wheels 
               8  Cross member 
               9  Mast 
               10  Mast 
               11  Loading platform 
               12  Flexible pulling device 
               13  Lower pulley 
               14  Upper pulley 
               15  (Upper) Bearing block 
               16  Axis 
               17  Drive shaft 
               18  Drive device 
               19  Bearing block 
               20  Bearing block receptacle 
               21  Clamping screw 
               22  Strand 
               23  Strand 
               24  Connecting shaft 
               25  Guide profile 
               26  Guide profile 
               27  Base surface 
               28  (Central) Side surface 
               29  (Outer) Side surface 
               30  Open profile side 
               31  Guide roller 
               32  Guide roller 
               33  Recesses 
               34  Strut 
               35  Strut 
               36  Connecting plate 
               37  Base plate 
               38  Lower frame component 
               39  Side wall 
               40  Side wall 
               41  Stiffening rib 
               42  Stiffening rib 
               43  Main frame 
               44  Lateral profile 
               45  Lateral profile 
               46  Cross strut 
               47  Central cross strut 
               48  Upper cross strut 
               49  Diagonal strutting 
               50  Diagonal strutting 
               51  Further main frame 
               52  Lower cross strut 
               53  Diagonal strutting 
               54  Diagonal strutting 
               55  Central cross strut 
               56  Upper cross strut 
               57  Guide profile portion 
             A Front axle 
             B Rear axle 
             C Container 
             D Segment 
             H Loading and unloading height 
             S Steering axles 
             R Reverse direction of travel 
             T Tensioning direction 
             F Forward direction of travel 
             X Transverse extension 
             Y Overall height 
             Z Lifting and lowering direction