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CROSS-REFERENCE 
   This is a national stage application of International Application No. PCT/EP02/02021, filed Feb. 26, 2002. The invention relates to a drilling device with a drive unit for advance and rotation for a rod assembly of a plurality of interconnected pipe sections and claims the priority of the German patent application 101 10 399.9, the contents of which are incorporated by reference. 
   STATEMENT OF FEDERAL SPONSORSHIP 
   Not Applicable 
   PARTIES OF JOINT RESEARCH AGREEMENT 
   Not Applicable 
   BACKGROUND 
   With these kinds of drilling devices, which may also comprise an impact drive unit and/or a vibration drive unit apart from the drive unit for advance and rotation, the rod assembly is used for the transmission of pushing forces and torque onto the drilling tool as well as for the transmission of pulling forces when taking out the rod assembly out of a drilling hole against the drilling direction, as normally done. Furthermore drilling rod assemblies for wet drilling are used to transport drilling fluid in direction of the drilling tool e.g. for the hydraulic mining of the soil. Drilling rod assemblies thus are subject to large static and dynamic load and thus require connections for the single pipe sections, which can cope with these loads and are, if necessary, liquid tight. 
   In practical use screwed connections are normally used as rod connections. These do however make time consuming screwing processes, often with use of special rod screwing devices, necessary on the one hand and are especially extremely sensitive to soiling and mechanical damage. Additionally, screwed drilling rod assemblies allow only one direction of rotation during drilling, as unscrewing of the connection would result otherwise. Even if the time effort for applying the screwing device, the actual screwing and the withdrawal of the screwing device per rod section is small, the related stop periods add up substantially with increasing rod assembly or drilling length. 
   BRIEF SUMMARY 
   The invention is thus directed to a drilling rod assembly of multiple sections, which sections can be interconnected and taken apart in a time-saving manner. 
   This is possible with a drilling device according to the invention, where the pipe sections are braced among each others by means of a tension rod situated inside the pipe. The tension rod allows to do without a screwing connection and instead to do with a simple plug-type connection, e.g. a positive fit plug type connection. Such a plug-type connection can be made of pipe sections inserted into each other in a sleeve manner. 
   The tension rod can be made of massive sections or can also be made of pipe sections (inner pipe sections). In this manner it is possible to transport the drilling fluid through a pipe type tension rod to the drilling head and to transport the drilling fluid back through a ring shaped channel between the tension rod (inner rod assembly) and the outer rod assembly or to work with a driving fluid for a MUD-motor as well as a drilling fluid separately therefrom. 
   The pipe sections of the outer and/or the inner rod assembly or the tension rod respectively can be interconnected with positive fit, e.g. by means of bayonet catches, which allow a fast and secure connection and separation of the pipe sections. 
   It can be of advantage, if the inner pipe sections have a receiver at one end with an opening for inserting there-through at least one lockin stop. The other pipe end is then provided with at least one corresponding locking stop, which for locking and unlocking only needs to be turned through 90°. 
   In the proximity of the locking stop a carrier stop can be arranged, which co-operates with a corresponding stop of the respective outer pipe section. In a like manner a carrier stop for the locking stop can be arranged in the proximity of the receiver of the inner pipe sections, which also corresponds with a stop of the respective outer pipe section. 
   To allow this co-operation, the outer pipe sections can be provided with a inner collar, which has a longitudinal slit for inserting there-through the carrier stop on the inner pipe section. The inner collar can pass into a ring groove for the carrier stop. 
   Since the section of the outer pipe and the tension rod can be interconnected without screwing, they should be provided with at least one key surface to create a torque proof connection in both directions and to allow an easy and fast locking for the tension rod by means of a key. 
   The tension rod can also be made of separate rope sections, which can be interconnected by means of a connector having a hook and a ring. In this case at least one carrier stop can also be provided in the proximity of the hook and/or at least one carrier stop can be provided in the proximity of the ring also. These stops then also co-operated with slit inner collars of the outer pipe sections. 
   Preferably the carrier stops are arranged in pairs in positions opposing each other. 
   The invention will be described in detail by means of the drawings, which only show possible embodiments. In the drawings 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  shows an outer pipe section, 
       FIG. 2  shows a inner section in the form of a massive rod, 
       FIG. 3  shows two interconnected rod assembly sections of pipe sections according to  FIGS. 1 and 2 , 
       FIG. 4  shows a rod assembly cross-section along the line IV—IV in  FIG. 3 , 
       FIG. 5  shows a rod assembly cross section along the line V—V in  FIG. 3 , 
       FIG. 6  shows the front view of a rearward inner pipe section and 
       FIG. 7  shows two pipe sections interconnected by means of a robe type tension rod. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   The drilling rod assembly is essentially made of a drilling head  1  with nozzles  2  for a drilling fluid as well as inner sections  4 . The outer pipe sections  3  have a sleeve  5  with at least one key surface  6  at one end as well as a pivot  7  at the other end with at least one corresponding key surface  8  as well as a ring grove  9  for a seal (not shown). 
   The inner section  4  is made of a massive rod ( FIG. 2 ) and also has a sleeve  11  at one end with at least one key surface  12  and a pivot  13  at the other end with at least one corresponding key surface  14  as well as locking stops  15 . 
   The outer pipe section  3  furthermore has an inner collar  16  with two longitudinal slits opposing one another, which cross section corresponds to the outline of the carrier stops  19  at the rearward end of a pipe type inner section  4  and—like shown in FIG.  4 —are situated rotated by 90° with respect to the carrier stops. In proximity to the inner collar  16  is a inner surface grove  20  of the outer pipe sections  3 , into which the carrier stops  19  mesh in the coupled state of the two pipe sections  3 ,  4 . Furthermore the front end of the outer pipe section  3  has an inner collar  21 , which, similar to the inner collar  16 , has two opposing longitudinal slits  17 ,  18  ( FIG. 4 ). 
   The rearward end of the inner pipe section  4  is provided with a receiver  22  for the carrier stops  15  at the front end of the neighbouring inner pipe section  4 . In a coupled state these carrier stops  15  are situated behind a band  23  at the rearward end of the inner pipe sections  4  shown left in  FIG. 3  or the front respectively, which band  23  is provided with two opposing longitudinal slits  24 ,  25  ( FIG. 5 ) for inserting the carrier stops  15 . At the front end of the inner pipe sections  4  further carrier stops  26  are situated, which can be inserted through the longitudinal slits  17 ,  18  in the inner collar  21  of the outer pipe section  3  and which serve as locking for the two pipe sections  3 ,  4  after a 90°-turn together with the other carrier stops  15  on the inner pipe section  4  ( FIG. 5 ). 
   In the coupled state, the rod assembly has a continuous inner boring  27  as well as a continuous channel of separate ring shape sections  28 ,  29 ,  30 , which surround the inner pipe sections  4  and are interconnected by means of the longitudinal slits  17 ,  18 ;  24 ,  25 . In this manner it is possible to transport one single fluid to and fro through the rod assembly or to transport two fluids separately from each other in direction of the drilling head. 
   The complementary key surfaces  6 ,  8  at the outer pipe sections  3 , opposing each other in the coupled state, provide a torque proof plug-type connection  11 ,  13  in both directions between the outer pipe sections  3 ,  4 . A further plug-type connection, torque proof in both turning directions, results in the coupled state from the complementary key surfaces  12 ,  14 , also opposing each other, at the inner sections  4  of the tension rod embodiment according to  FIG. 2 . 
   The inner sections  4  are interconnected with the outer pipe sections  3  by means of the carrier stops  15  and the band  23  as well as the carrier stops  19 ,  26  and the inner collars  16 ,  21  in such a fashion, that the rods  3 ,  4  form a unit and can be pulled out of a drilling hole (to the right in  FIG. 3 ) in one piece by means of the tension rod or inner rod assembly respectively being made of the inner pipe sections  4 , although the outer pipe sections  3  are only interconnected by means of the plug type connections  11 ,  13 . 
   In the embodiment of  FIG. 7  two outer pipe sections  20  are interconnected in a manner torque proof in both directions by means of a sleeve type plug type connection  31  like in the embodiments of  FIGS. 1 to 5 . The outer pipe sections  30  are provided with two inner collars  32 ,  33 , which are provided in longitudinal slits  34 ,  35  like the inner collars  16 ,  20 . 
   Within the rod assembly having outer pipe sections  30  a tension rod in form of separate rope sections  36 ,  37  protrudes, which are provided with carrier stops  38  at the front end and locking stops  39  at the rearward end as well as being interconnected by means of hooks  41  meshing with rings  40 . The rearward locking stops  39  are provided to position the rope sections  36 ,  37  in co-operation with the carrier stops  38  situated at the front and to secure the rope sections  36 ,  37  against falling out of the pipe sections. With aid of the interconnected rope sections  36 ,  37  the outer pipe sections  30  can be braced together to form a uniform rod assembly torque proof in both directions. Additionally the rope  36 ,  37  allows the rod assembly to be pulled out of the drilling hole completely in both directions although only been connected by means of plug type connections  31 . 
   The inside of the rod assembly of rod sections  30  is made of separate sections  42  which are in connection with each other by means of the mentioned longitudinal slits  34 ,  35  in the inner collars  32 ,  33 . The rod assembly therefore can also be used for the transportation of a drilling or a driving liquid. 
   The rod assembly according to the invention can especially be used with a steerable drilling head, as described in U.S. Pat. No. 5,322,391, which content is herewith incorporated in this document.

Summary:
In a drilling device with a drive unit for rotation and advance the rod assembly has a plurality of pipe sections interconnected by means of plug-type connections torque proof in both directions. A tension rod protrudes through the interior of the rod assembling. The pipe sections are braced among each other with aid of the tension rod. The tension rod can be made of pipe sections or of a tension rope and allows the possibility, that the rope assembly can be moved in its integrity against the drilling direction.