Abstract:
A device for driving and extraction of sheet piles into or from the ground, respectively, has a leader on which an exciter cell is guided. The exciter cell is coupled with an advancing system by way of which it can be moved in linear manner. The exciter cell is rigidly connected with at least one guide element that is exclusively guided on the leader and elastically connected with the advancing system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Applicants claim priority under 35 U.S.C. §119 of European Application No. 10013794,2 filed on Oct. 20, 2010, the disclosure of which is incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a device for driving and/or extraction of sheet piles and the like into and from the ground, respectively. The device comprises a leader on which an exciter cell is guided. The exciter cell is coupled with an advancing system for moving it in a linear manner. 
         [0004]    2. The Prior Art 
         [0005]    Vibration generators, so-called exciter cells, are used for driving sheet piles or the like into the ground and extracting them, respectively. These generators are attached to the lifting carriage of a leader of a construction machine, and a collet is provided on them, on which the sheet pile can be attached. Such an arrangement is known, for example, from German Patent Application No. DE 43 12 368 A1. In this connection, the exciter cell is usually disposed in a hood, which is connected with an equipment carriage that is connected with the lifting carriage of the leader. The lifting carriage of the leader is coupled with an advancing system by way of traction cables as well as load cables. The load cables are disposed on the side of the lifting carriage that faces the ground, so that a traction force that acts on the load cable acts in the direction of the ground, in other words as a top load. Such arrangements have fundamentally proven themselves for introducing sheet piles into the ground or extracting them, respectively. However, there are significant friction losses as well as preload force losses at the guide of the exciter cell in the hood and the guide of the lifting carriage on the leader, caused by tilting and jamming of the guides. Furthermore, great wear is caused by this. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a device for driving and/or extraction of sheet piles and the like into and from the ground, respectively, comprising a leader, on which an exciter cell is guided, in which device such friction and preload force losses are reduced. The exciter cell is rigidly connected with at least one guide element that is exclusively guided on the leader and elastically connected with the advancing system. 
         [0007]    By means of the rigid connection between the exciter cell and the at least one guide element, which is exclusively guided on the leader, preload losses due to vibration and friction are eliminated to a great extent. The vibrations that are now directly transferred to the leader are uncoupled by way of the elastic connection between advancing system and the at least one guide. In this connection, in the present case, the term “elastic” connection is to be understood to mean a connection that has clearly greater elasticity than the direct coupling by way of steel cables that is known in the state of the art, since these cables transfer the vibrations transferred to the leader and would cause damage to the leader and/or to the advancing system in this connection. 
         [0008]    In a further development of the invention, coupling of the at least one guide element to the advancing system takes place by way of at least one cable that is configured to be elastic. Uncoupling of the vibrations applied to the leader by way of the at least one guide element is brought about as the result of the elasticity of the cable. It is advantageous if the at least one cable is produced from high-strength plastic fibers, preferably polyethylene fibers made from ultra-high-crystalline molecular polyethylene or from glass fibers. Such cables are characterized in that they demonstrate great elasticity and, simultaneously, low weight. 
         [0009]    In the following, all elongated, flexible elements similar to cables, for the transfer of traction forces, including chains, for example, are to be subsumed in the term “cable.” In this connection, a cable whose traction force acts in the direction of the ground is referred to as a “load cable,” and a cable whose traction force acts counter to the ground is referred to as a “traction cable.” 
         [0010]    In another embodiment of the invention, coupling of the at least one guide element to the advancing system takes place by way of at least one cable, whereby at least one cable is connected with at least one spring module. In this way, uncoupling of the vibrations applied to the leader by way of the at least one guide element is achieved. In this connection, the at least one spring module can be configured as a spring packet composed of cylindrical helical springs, plate springs, gas pressure springs, torsion bar springs and/or flexion springs. 
         [0011]    In another embodiment of the invention, the at least one spring module is formed from at least one rocker, which is connected with the at least one guide element by way of an axle, so as to pivot. A first clamping unit is disposed on the at least one rocker, at a distance from its pivot axle, and a second clamping unit for an elastic element, preferably an elastic loop, is disposed at a distance from the rocker. At least one cable is attached to the rocker on the side that lies opposite the pivot axle. In this connection, the elastic element, preferably the elastic loop, takes on uncoupling of the vibrations applied to the leader by way of the at least one guide element. Additional securing is brought about in that even in the event of failure of the elastic element or the elastic loop, the at least one guide element continues to be connected with the at least one traction cable by way of the at least one rocker. 
         [0012]    In a further development of the invention, two such rockers are disposed on the at least one guide element, vertically spaced apart from one another and preferably projecting in opposite directions. One rocker is connected with at least one traction cable and one rocker is connected with at least one load cable. The elastic element assigned to each rocker, which is preferably configured as an elastic loop, is disposed on the pivot axle of the opposite rocker, connected with the at least one guide element. In this way, uncoupling of the vibrations applied to the leader is achieved by two elastic elements or elastic loops. One elastic element brings about uncoupling when stress is applied by the traction cable, and one elastic cable brings about uncoupling when stress is applied by the load cable. In this way, the stress on the elastic elements is reduced, thereby increasing their useful lifetime. Furthermore, the preload force for traction and pressure can be adjusted separately, by the use of different loops. With this arrangement, a linear spring characteristic line is achieved, which allows good uncoupling. It is advantageous if the pivot axle of the first rocker is disposed horizontally offset from the pivot axle of the second rocker. 
         [0013]    It is advantageous if the elastic elements are configured as elastic loops that are produced from glass-fiber-reinforced plastic material. This material has good elastic properties. In this connection, the fibers are durable for a very long time and have great resistance to friction wear, moisture, and UV radiation. 
         [0014]    In an embodiment of the invention, the at least one guide element is disposed on a carriage that is rigidly connected with the exciter cell. In this connection, the carriage preferably has a length that projects beyond the exciter cell in terms of its length. The force that acts on the at least one guide element is reduced by the use of a long carriage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention. 
           [0016]    In the drawings, wherein similar reference characters denote similar elements throughout the several views: 
           [0017]      FIG. 1  shows the spatial representation of the exciter cell with carriage disposed on it, and coupling to an advancing system; 
           [0018]      FIG. 2  shows the schematic representation of the exciter cell with carriage disposed on it, with an alternative spring module; 
           [0019]      FIG. 3  shows the schematic representation of an exciter cell with carriage disposed on it, with a spring module in a third embodiment, and 
           [0020]      FIG. 4  shows the arrangement from  FIG. 3  under the effect of a traction force on the traction cable. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    Referring now in detail to the drawings, the device for driving and/or extraction of sheet piles into or from the ground, respectively, selected as an exemplary embodiment, essentially consists of leader  7  disposed on a construction machine, having a carriage  2  that is disposed to be displaceable on a leader guide  71 . An exciter cell  1  is attached to the carriage  2 , on which cell a collet  11  for accommodating a sheet pile is disposed on the bottom side. Carriage  2  is connected with the advancing system of leader  7  by way of traction cables  3  attached on carriage  2  on both sides, as well as by way of load cables  4  disposed on carriage  2  on both sides. The guide of cables  3 ,  4  as well as their connection with the advancing system, are known, for example, from DE 43 12 368 A1, and therefore do not need to be described further at this point. The same holds true for the structure of exciter cell  1 . Such vibration generators are known to a person skilled in the art, in the most varied embodiments. 
         [0022]    In the exemplary embodiment, exciter cell  1  has an extensively block-shaped housing that is disposed between two side cheeks  20  of carriage  2 , which are disposed parallel, and is connected with these side cheeks  20  by way of screw connections. On its side facing away from exciter cell  1 , two guide rails  21  are disposed on carriage  2 , at a distance from one another, by way of which carriage  2  is mounted on leader  7  in a displaceable manner. Laterally, projecting metal sheets  22  are affixed to guide rails  21 . In this connection, metal sheets  22  are disposed in such a manner that metal sheets  22  of upper guide rail  21  project in the direction of leader  7 , and metal sheets  22  of lower guide rail  21 , which faces the ground, project in the direction of the exciter cell  1 . An axle  221  for attachment of a traction cable  3  or a load cable  4 , respectively, is disposed on each of metal sheets  22 . In this connection, traction cables  3  engage on axles  221  of metal sheets  22  of lower guide rail  21 ; load cables  4  are connected with axles  221  of metal sheets  22  of upper guide rail  21 . Spring packets  5  are integrated into traction cables  3  and load cables  4 , which packets are represented, in simplified form, as cylindrical helical springs in  FIG. 1 . Traction cables  3  and load cables  4  are connected with axles  221  of metal sheets  22  by way of eyes  31 ,  41 . 
         [0023]    Furthermore, a hydraulic block  6  for connecting hydraulic lines—not shown—is disposed on carriage  2 , opposite the upper guide rail  21 . In this connection, hydraulic block  6  is connected with carriage  2  by way of resilient elements, so that transfer of vibrations to the connected hydraulic lines is minimized. In the exemplary embodiment, the resilient elements are formed by elastomer blocks  61 . 
         [0024]    In the embodiment according to  FIG. 2 , a rocker  23  is connected with guide rail  21 , so as to pivot, by way of a pivot axle  231 , on both sides of upper guide rail  21 . In this connection, the force engagement points of cables  3 ,  4  as well as the traction/load loop  233  are disposed offset from pivot axle  231  of rocker  23 . Traction cable  3  and load cable  4  are attached to rocker  23  on a common vertical axis. A clamping axle  232  for accommodating a traction/load loop  233  is disposed on the rocker  23 , at a distance from pivot axle  231 . The traction/load loop  233  is clamped between clamping axle  232  and a second clamping axle  24  disposed on lower guide rail  21 . 
         [0025]    The spring module of the arrangement according to  FIG. 2  functions as follows: If a traction force is applied to traction cable  3 , then rocker  23  pivots about axle  231 , thereby causing clamping axle  232  to describe an arc in the clockwise direction. This causes traction/load loop  233  to be tensed, thereby achieving the desired uncoupling. To apply a top load to exciter cell  1 , a traction force is applied to load cable  4 , thereby pivoting rocker  23  in the counter-clockwise direction, about pivot axle  231 . In this connection, clamping axle  232  describes an arc in the counter-clockwise direction, thereby again tensing traction/load loop  233 , which brings about uncoupling. 
         [0026]    In the embodiment according to  FIG. 3 , a rocker  25 ,  26  is disposed both on upper guide rail  21  and on lower guide rail  21 , on both sides. In this connection, a traction rocker  25  is mounted on guide rail  21 , eccentrically on upper guide rail  21 , on both sides, by way of a pivot axle  251 , in such a manner that it projects in the direction of exciter cell  1 . Similarly, a load rocker  26  is connected with guide rail  21 , so as to pivot, by way of an eccentrically disposed pivot axle  261 , on lower guide rail  21  of the carriage  2 , on both sides. Load rocker  26  is disposed to project in the direction of leader  7 . Clamping axles  252 ,  262  are disposed on rockers  25 ,  26 , offset from pivot axle  251 ,  261 . In this connection, clamping axles  252 ,  262  are positioned in such a manner that they are positioned to lie opposite each of the pivot axles  251 ,  261  of the opposite rockers  25 ,  26 , in the case of horizontal orientation of the rockers  25 ,  26 . A load loop  263  extends between clamping axle  262  of the load rocker  26  and pivot axle  251  of traction rocker  25 , and an elastic traction loop  253  extends between pivot axle  261  of load rocker  26  and clamping axle  252  of traction rocker  25 , on both sides of guide rails  21 . Traction loop  253  and load loop  263  are produced from glass-fiber-reinforced plastic material. Alternatively, these loops can also be produced from high-strength plastic fibers, for example from ultra-high-crystalline molecular polyethylene. 
         [0027]    The method of functioning of the arrangement according to  FIG. 3  is illustrated in  FIG. 4 . If a traction force F is applied to traction cable  3 , traction rocker  25  is displaced by preload path s, thereby increasing the distance between pivot axle  261  of load rocker  26  and clamping axle  252  of the traction rocker. In this way, traction loop  253  is tensed, thereby achieving uncoupling. The distance between pivot axle  251  of traction rocker  25  and clamping axle  262  of load rocker  26  remains unchanged. When a traction force is applied to load cable  4 , load loop  263  is tensed accordingly. Traction loop  253  remains unstressed. In the case of an alternating driving and extraction process, alternate stress on traction loop  253  and load loop  263  therefore takes place, thereby achieving uncoupling. In this connection, the preload force for “driving” and “extraction” can be separately adjusted by separate dimensioning of traction loop  253  and load loop  263 . In the case of this embodiment, as well, carriage  2  continues to be connected with traction cable  3 , by way of traction rocker  25 , in the event of failure of traction loop  253  and/or load loop  263 . 
         [0028]    Accordingly, while only a few embodiments of the present invention have been shown and described, it is obvious that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.