Abstract:
A simply-designed, multi-purpose transport module with which heavy loads can be moved over the ground has the following features: a frame, on which the load is laid, is positioned on the floor. A support is positioned on the floor. The ground loading pressure of the frame, on an increase of the ground pressure loading of the support, and the ground pressure loading of the support, on an increase of the ground pressure loading of the frame, can be reduced to below the unloaded weight through an actuator of the frame or of the support. The frame and the support have a first pair of inclined paths through which the frame can be supported on the support and the frame is displaceable horizontally with respect to the support on achieving a sufficient reduction of its ground pressure loading. The frame and the support have a second pair of inclined paths through which the support can be supported on the frame and the support is displaceable horizontally with respect to the frame on achieving a sufficient reduction of its ground pressure loading. A load can be moved forward in a step-wise manner with such a transport module.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a transport module with which heavy loads can be moved over a floor. 
     Various systems are known and in use for the horizontal transport of large heavy loads. The principles used are for example: 
     a) shifting the heavy load on sliding surfaces with which the supports of the heavy load ere provided; 
     b) transport on wheels with the aid of transport carriages that have tires or steel wheels rolling on rails; 
     c) shifting a load that is suspended by the use of pneumostatic or hydrostatic bearings; 
     d) travel in which the load is both raised and transported horizontally. 
     Horizontal load movement can take place continuously in cases b) and c). In case a) it is at least discontinuous. In case d) the movement is theoretically discontinuous, Each of the known solutions for the horizontal transport of large heavy loads has certain disadvantages. For example, high driving forces are required when shifting on sliding surfaces. Energy consumption is relatively high, especially when shifting on sliding surfaces or on a cushion and when moving. The drives are expensive and cumbersome and impose high requirements on floor quality. 
     SUMMARY OF THE INVENTION 
     Hence, the basic object of the invention is to provide a transport module that can be used as an independent unit individually or together with other similar modules for moving a heavy load, that allows moving the load with a relatively low energy consumption, and that imposes no special requirements on the floor. 
     A transport module of the invention has as a main part a frame on which the load can be placed and that can be placed on the floor. As a second main part, the transport module has a support that can likewise be placed on the floor. By means of an actuator that is part of the frame or the support, the force applied to the floor by the frame can be reduced by increasing the force with which the support contacts the floor and the force with which the support contacts the floor can be reduced below its own weight by increasing the force with which the frame contacts the floor. The frame and the support have a first pair of steep paths formed by inclined surfaces of wedge-shaped components of the module, by which the frame can be supported on the support. By means of the actuator, the normal force between the frame and the floor, in other words the force directed against the floor by the frame and hence the frictional force between the floor and the frame, can be reduced to the point where the frame, and the load with it, travels along the sloping path of the support and is thus moved horizontally. At this time the frame is raised by the actuator further and further relative to the support. The speed with which the frame is raised can be used to control the speed at which the load moves. Normally the frame does not lift off the floor, since the horizontal force produced by the sloping paths and the combined weight of the frame and the load overcomes the force of friction between the frame and the floor even before the frame lifts off the floor. Energy consumption is therefore lower than in a form of movement in which the load is raised completely from the floor. It is also less than in a type of movement in which the normal force and consequently the force of friction is not reduced. 
     The frame and the support have a second pair of sloping paths by which the support can be supported on the frame., The force with which the support contacts the floor can also be reduced by the actuator so that the support always follows the frame. A heavy load can therefore be moved discontinuously in a transport module according to the invention. 
     A transport module according to the invention can be used individually, but preferably together with one or more additional transport modules to move a load. The actuators of the various transport modules are then controlled relative to one another. 
     The support can support the frame located above it in a simple fashion. The support, on the other hand, hangs from the frame when it is moved. For this purpose, the frame uses second guide elements to grip beneath first guide elements located on opposite sides of the support. The second pair of steep, or sloping, paths is located on the first and second guide elements. 
     In the partial step of the movement in which the load is shifted, the weight of the load and at least a portion of the weight of the frame must be supported by the support. This is accomplished by means of the first pair of steep paths. In order not to allow the load on the parts to become too high, especially the pressure per unit area, the first pair of steep paths is therefore advantageously formed by a pair of steep surfaces that slide on one another. In the partial step in which the support follows the frame, at least a portion of the weight of the support is conducted through the second pair of steep paths into the frame and through the latter into the floor. The forces that are transmitted through the second pair of steep paths are therefore much smaller than the forces that are transmitted by the first pair of steep paths. Advantageously, therefore, the first pair of steep paths is formed by a steep surface and by rolling bodies that roll on it. Therefore the support moves even when the load on the floor exerted by the support is reduced slightly and the frictional force between the support and the floor is reduced accordingly. Three rollers for suspending the support on the frame will suffice if the rollers are arranged in accordance with other features of the invention. 
     Because the floor underneath the transport module can be uneven, a universal joint is provided in the support or in the frame that allows the corresponding guide block with the steep paths to tilt with respect to the other parts of the frame or the support to allow compensation for unevenness of the floor. 
     According to a feature of the invention, the actuator is associated with the support, and can be used to change the relative vertical position of a guide block that includes the steep paths of the support with respect to a floor-supporting body of the support. The association of the actuator with the support has the advantage that the guide blocks and the steep paths of the support and frame can be relatively far from the floor. The greater the distance between the guide blocks with the steep paths from the floor, the better they are protected against contamination. 
     The actuator is advantageously arranged in such fashion that its adjusting movement takes place at least approximately simply vertically with respect to the floor. Thus, adjustment of the actuator alone does not produce any horizontal movement of the frame or the support that would be superimposed on the movement along the steep paths. The actuator is preferably formed by a double-acting hydraulic piston-cylinder unit, since high forces can be produced even with relatively small hydraulic drive components. The use of a hydraulic piston-cylinder unit as an actuator therefore permits a compact design for the transport module. 
     By designing the transport module to shift a heavy load in a straight line, it is also possible to shift the heavy load parallel. Therefore, the load can be moved while retaining its alignment in a plane. This is accomplished by virtue of the fact that a first guide block of the frame with its steep paths and a second guide block of the support with its steep paths can be rotated in common around a vertical axis relative to a floor support body. Preferably, the two guide blocks can be rotated in an angle range of at least 270° relative to the floor support body of the frame so that a load can move parallel to a plane at every point. 
     The movement possibilities for a load that rests on a plurality of transport modules according to the invention are further expanded by the fact that the transport modules are designed according to further features of the invention. A load can then be rotated or can round a curve, in other words the alignment of a load can be changed. It is important for this type of movement th at there be lateral play between the two guide blocks of the frame and the support and that centering means be provided for centering the guide blocks with respect to one another in a neutral central position. The lateral play between the two guide blocks permits a slight transverse shift between the two guide blocks, and the centering means ensure that at the beginning of a movement step there are equal distances on both sides between the two guide blocks. The alignment of a load can also be modified using transport modules if the two guide blocks are not rotatable with respect to the floor support body of the frame. However, the transport modules must then be brought, suitably aligned, beneath the load. The central axis of the movement cannot simply be changed. When rounding a curve with a change in load orientation, the guide block of the frame is not only shifted in the transverse direction but is also rotated slightly. A rotary joint can be provided in the support so that the guide block of the support can participate in the rotation of the guide block of the frame. 
     It is advantageous if, the relative movement between the frame and the support in the direction of travel can be detected by a travel sensor. Then a plurality of transport modules supporting a load can be controlled precisely as the load rounds a curve. 
     A supporting part of the frame that has the supporting surface for the load can be adjustable heightwise. Then a transport module with the support part lowered can easily be placed beneath a load supported by other supports. The supporting part is then moved upward and the load lifted free of the other supports. The latter can then be removed. The process is reversed when setting down the load on other supports. A depression or elevation in the floor over which one of a plurality of transport modules carrying the same load is traveling, can be compensated. There is also a freer choice of support locations on the load, which can now have different height settings. 
     The supporting part is preferably adjustable heightwise by means of a hydraulic cylinder. The weight of the load can be determined easily by pressure measurement, with assurance of course being provided that the load is supported hydraulically on each of the transport modules supporting it, in other words there is a fluid cushion between the piston and the cylinder housing in each hydraulic cylinder. 
     The movement of the supporting surface for the load on the frame is not fixed relative to the floor on which the frame stands, and in particular the travel of the supporting surface need not be parallel to the floor. Instead, the supporting surface can adjust itself depending on the conditions prevailing between the load and the floor. 
     The drawings show an embodiment of a transport module according to the invention as well as several schematic diagrams to explain the motion process during the shifting of a load and to clarify the movement possibilities for a load. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With the above and other objects and advantages in view, the present invention will become more clearly understood in connection with the detailed description of a preferred embodiment, when considered with the accompanying drawings, of which: 
     FIG. 1 shows the embodiment in a side view, with the frame partially cut away for a better view of the support; 
     FIG. 2 is a section along line II—II in FIG. 1, in which the support is shown partially only in a front view; 
     FIG. 3 shows a section along line IV—IV in FIG. 1 on a slightly enlarged scale; 
     FIG. 4 shows a partial section along line IV—IV in FIG. 3 on an enlarged scale; 
     FIG. 5 shows schematically the frame and the support of a transport module at the beginning of a movement cycle; 
     FIG. 6 shows the transport module according to FIG. 5 following a step of the frame relative to the support; 
     FIG. 7 shows the transport module according to FIGS. 5 and 6 after the support follows; 
     FIG. 8 shows a load supported by four transport modules, with the load being displaced while maintaining its orientation; 
     FIG. 9 shows a load supported by four transport modules, with the load being rotated around an axis located outside of itself; and 
     FIG. 10 shows a load supported by four transport modules that is rotated around its own axis, with the four transport modules each being located the same distance from the axis and located in the corners of a square. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The transport module  80  shown in FIGS. 1 to  4  can be imagined as being composed of two main parts, namely a frame  10  and a support  11 , with one main part being shifted relative to the other main part resting firmly on the floor in each case to move a load. The load does not move when support  11  moves. 
     Frame  10  has a pot-shaped floor-abutting body consisting of a circularly cylindrical jacket  12  and a plate  13  fastened by bolts  14  to one end of jacket  12 . The jacket  12  can rest on the floor by the free end. Openings  15  are provided in the jacket  12  to reduce the weight, and the openings also allow a view of the support  11  located inside the frame. 
     A stepped bore  16  is located centrally in the plate  13 . In the vicinity of this bore  16 , a single-acting lifting cylinder  82  is mounted on the plate  13 . The bore  16  is covered on the top firstly by a bolted-on intermediate plate  83  provided with a hollow for centering the lifting cylinder  82 . An adjustment between the size of the bore  16  and the lifting cylinder  82  can be made by using the intermediate plate  83 , with the cylinder preferably being chosen from commercial sizes. 
     If no lifting cylinder  82  is mounted, the bore  16  can also be protected against the penetration of dirt by a cover that does not project beyond the plate  13 . 
     The lifting cylinder  82  has an essentially bipartite cylinder housing  84  consisting of a housing pot  85  and a cylinder head  86 . Inside the cylinder housing  83  a piston  87  is displaceable on which a piston rod  88  that has a diameter smaller than that of piston  87  is mounted, with the piston rod emerging through the cylinder head  86 . At its outer end the piston rod  88  is provided with a ball joint  89 , into which a supporting part  90  is inserted that has a ball segment  91  whose radius matches the radius of ball joint  89 . A supporting surface  92  for a load is located on a flange  93  of the supporting part  90  that projects beyond the ball segment  91 . This, and with it the support surface, are therefore tiltable within limits on all sides. When the piston rod  88  is retracted, the force of gravity and a coil compression spring  94  cooperate so that the spring is accommodated in the annular space formed by the cylinder housing  84 , the piston  87 , and the piston rod  88 . An ability of the supporting part with the supporting surface to tilt in all directions relative to the other parts of the frame is also advantageously provided if the supporting part is not height-adjustable. 
     To transport a load, a plurality of transport modules  80  is normally used. Initially, the pressure chambers located between the piston  87  and the bottom of the housing part  85  are charged with a pressure medium until the piston  87  extends for approximately half the lifting height. Then the pressure chambers are cut off from the pressure medium source. The transport modules  80  that are used are subdivided into lifting groups so that a statically determined support for the load is provided and the pressure chambers of a lifting group are connected hydraulically with one another. Pressure medium can flow back and forth between the pressure chambers of the transport modules  80  of a lifting group because the pistons are not originally in an end position. 
     A wedge-shaped guide block  20  of the frame  10  with a pin  21  that can rest by a collar  22  on the step  23  of the bore  16  is supported in the bore  16  so that it is rotatable around the central axis  24  of the frame  10  that normally extends essentially vertically relative to its floor support body consisting of jacket  12  and plate  13  when the transport module is in use. An axial bearing for the guide block  20  is formed by the collar  22  of the pin  21  and the step  23  of the bore  16 . 
     The guide block  20  can abut the plate  13  internally over a large area, as shown in FIG.  2 . There is a small space between the collar  22  of the pin  21  and the step  23  of the bore  16 . 
     Facing away from the plate  13 , the guide block  20  has a wedge surface  25  inclined approximately 10° to the plane of the plate  13 . On the wedge surface, at a distance from one another and parallel to one another, two L-shaped guide strips  26  are bolted so that a guide groove  27  is provided between each guide strip and wedge surface  25 , with the groove being open toward the other guide strip in each case. The two guide strips  26  extend in the direction of the greatest slope on the wedge surface  25 . 
     The support  11  is essentially formed by a hydraulic piston-cylinder unit  30 , which can stand on the floor by means of a floor plate  32  bolted to the cylinder  31 , and by means of a second wedge-shaped guide block  35  that has a wedge surface  36  facing the first guide block  20 , by which it is provided with a sliding support  37  that reduces friction. The slope of the wedge surface  36  is the same as the slope of the wedge surface  25 . The two guide blocks  20  and  35  can rest on one another over a large area by the two wedge surfaces  25  and  36 . 
     As is especially clear from FIG. 4, the guide block  35  has lateral guide strips  38  with which it engages the guide grooves  27  of the guide block  20 . Two ball bearings  40  are each fastened by a threaded bolt  39  to the other strip  38 , at a distance from one another. Another ball bearing  40  is mounted on one guide strip  38  by a threaded bolt  39  on the other guide strip  38 , centrally between the two ball bearings  40 . The three ball bearings  40  are therefore located at the corners of a triangle. They are each located in recesses  41  of the respective guide strips  38 . Their outer rings form rollers that can roll along the lower side walls of a guide groove  27 . As soon as the wedge surfaces  25  and  36  of the two guide blocks  20  and  35  abut one another, there is a distance between the ball bearings  40  and the corresponding side wall of the guide grooves  27 . Conversely, there is a distance between the wedge surfaces  25  and  36  when the ball bearings  40  abut the guide strips  26 , as shown in FIG.  4 . 
     It is clear from the figures that the distance between the two guide strips  26  of the guide block  20  is larger by a certain amount than the width of the guide block  35 , both in the vicinity of the guide strips  38  and also in an area below the latter. This means that transverse displacement is possible perpendicularly to the lengthwise direction of the guide strips, in addition to pivoting between the two guide blocks, because of the play that exists as a result of the different dimensions. If no external forces are applied, however, the two guide blocks  20  and  35  will assume a central position in which the spaces between the second guide block  35  and the two guide strips  26  of the guide block  20  will be the same size. The central position is caused by two centering devices  45 , each of which has two spring supports  46  and a compression spring  47  tensioned between the two spring supports. The two spring supports  46  and the compression springs  47  are located in a transverse groove  48  of the second guide block  35  covered by the sliding layer  37 . Each spring support consists of a pin  49  guided in the transverse groove  48  and a ball bearing  50  mounted on the pin, with the outer race of the bearing being able to roll along the bottom of a guide groove  27 . Each pin  49  is provided with an elongate recess  51  in the lengthwise direction of the transverse groove  48 , into which recess a pin  52  mounted in the guide block  35  projects. As a result, the outward travel of a pin  49  is limited. When the two guide blocks  20  and  35  assume the centered central position relative to one another, the pins  49  are pressed by compression springs  47  against the respective pins  52 . There is then a very small space between the ball bearings  50  and the guide strips  26  of the first guide block  20 . If the two guide blocks  20  and  35  are shifted transversely by more than this minimum distance, one pin  49  of a centering device  45  will be forced backward while the other remains at rest because of the pin  52 . As a result, the spring  47  will be pretensioned to a greater degree.and~will produce a restoring force. The two transverse grooves  48  and with them the two centering devices  45  are located at equal distances from the central axis of support  11 . 
     The piston-cylinder unit  30  is double-acting and has a piston rod  55  that projects from the cylinder  31 , with the rod being connected inside the cylinder  31  with a piston  54  shown in FIGS. 5 and 7 and which at its free end supports the guide block  35  by means of an adapter  56  and a universal joint  57 . The universal joint  57  allows the guide block  35  to tilt slightly relative to the central axis of the cylinder  31 . As a result, any unevenness in the floor that results in different alignments of the central axes of the frame and the support can be compensated. A rotary joint is formed between the piston  54  and the cylinder  31 . 
     The path that the support  10  and the frame  11  travel with respect to one another can be detected by a travel sensor  60  which is in the form of a potentiometer in the embodiment. Part  61  of the travel sensor that moves together with the frame  10  is accommodated in a groove  62  that is located in the wedge surface  25  of the guide block  20  and runs in the direction of its greatest slope. The part  61  contains a wound electrical resistance and an electrical wiping path. The wiper  63  is fastened in a recess in the guide block  25  of the support  11  and travels along the wound electrical resistance and on the wiping path. From the part  61 , three electrical cables not shown in greater detail, two of which are connected with the ends of the resistance and one with the wiping path, are brought out through a channel  64  located in axis  24 . Even when the travel sensor  60  is inclined to the horizontal in exactly the same way as the wedge surfaces  25  and  36 , the horizontal movement between the frame  10  and the support  11  can easily be detected since the slope is known. 
     A bead  70  of the guide block  20  located directly below the plate  13  is provided externally with teeth  71 . A pinion  72  meshes with these teeth, said pinion being driven by a hydraulic motor  73  fastened to the plate  13 . Alternatively a drive motor can also be mounted externally on the frame  10  and driven for example by a wheel connected nonrotatably with pinion  72  by a belt, chain, worm, or similar drive. 
     Starting with the position of a transport module  80  as shown for the frame  10  and the support  11  in FIG. 5, a load is now to be moved that rests on the frame  10 . For this purpose, a pressure is built up in the pressure chamber  75  of the cylinder  31  on the piston side and as a result a force is exerted on the frame  10  through the wedge surfaces of the guide blocks  20  and  35  that reduces the force with which they rest on the floor. Finally, a pressure is reached in which the force of friction between the frame  10  and the floor is so small that the frame begins to slide down the wedge surface  36  of the support  11  by its wedge surface  25 . As more pressure medium is added to the pressure chamber  75 , the piston rod  55  of the cylinder  31  gradually extends so that a speed for the sliding movement of the frame is established as a function of the speed of the extending movement of the piston rod. At the end of the free movement range of the frame  10  relative to the support  11 , the supply of oil to the pressure chamber  75  is halted so that the piston rod stops as well and the frame  10  rests firmly on the floor. As can be seen from FIG. 6, which shows the state that has been reached, the frame  10  has now moved to the right while the support  11  is in the same position as in FIG.  5 . Now the pressure is relieved on the piston side of pressure chamber  75  and a pressure is developed in the pressure chamber  76  on the piston rod side. The ball bearings  40  on guide block  35  rest on the guide strips  26  of the guide block  20 . The support  11  hangs from frame  10 , so to speak. Finally, the frictional force between the support  11  and the floor is so small that the ball bearings  40  begin to roll down guide strips  26 . In order for the movement not to end immediately once again, the piston rod  55  is gradually retracted into the cylinder  31 , so that the support  11  rolls on the frame  10  up to the end of the possible movement range. Finally the support  11  assumes the position shown in FIG.  7 . It is clear that the relative position between the frame  10  and the support  11  is the same as in FIG. 5, but that both parts of transport module  80  have moved a certain distance from the position shown in FIG.  5 . 
     Basically, a load can be transported using only one transport module. Usually, however, a heavy load is supported by a plurality of transport modules. If this load is to be moved in a straight line, the guide blocks  20  and  35  of all the transport modules used are all aligned in the same direction as shown in FIG. 8, which shows a load  81  supported by four transport modules  80 . The direction of the greatest slope of the wedge surfaces on the frame  10  and on the support  11  are indicated by the arrows in the transport modules. The movement direction of the load corresponds to the direction of these arrows. If the load is to be moved in a direction other than that shown in FIG. 8, in a state in which the support  11  is lifted slightly off the floor by pressurizing the pressure chamber  76  on the piston rod side, the guide block  20  of the frame  10  as well as the entire support is rotated with the aid of the hydraulic motor  73  around the axis  24  by the desired angle relative to the plate  13  and the jacket  12  of the frame. The wedge surfaces of all of the transport modules are then once again aligned in the same direction in which the load is being moved while retaining its orientation. 
     If it is desired to move a load around a curved curve, and thereby also change the orientation of the load to correspond to the curvature of the curve, the wedge surfaces of the transport modules  80  supporting the load must be aligned differently. In FIG. 9, the arrows in the transport modules  80  indicate the alignment for the case in which the transport modules support a load  81  at the four corners of a square and the load is to be pivoted around a pivot point  82  located outside this square. The guide blocks  20  and  35  are aligned so that the direction of the maximum slope on the wedge surfaces is perpendicular to lines that connect the pivot point  82  with the central axis  24  of the respective frame  10  and which are shown dashed in FIG.  9 . 
     When rounding a curve according to FIG. 9, the movement of the guide block in the direction of the maximum slope of the wedge surfaces has a transverse movement and a pivoting movement superimposed upon it. This superimposition is possible because of the play that exists in the transverse direction between the two guide blocks. Without this play, the two guide blocks would jam and prevent travel around a curve. The pivoting between the guide blocks  20  and  35  that exists at the end of the movement of the frame  10  relative to the support  11  is canceled by the centering devices  45  while the support  11  follows the frame. The next movement step can be made without additional rotation of the guide blocks relative to the floor support bodies  12 ,  13  of the frame  10 . With very slight curvatures of the line of movement of a load, it can become necessary to shorten the step length. 
     According to FIG. 10 a load  81  supported by a plurality of transport modules  80  can also be rotated on the spot. Once again the edge surfaces are aligned perpendicularly to lines that extend from the pivot point  82  of the load to the axis  24  of the frame.