Directional drilling device

Abstract

Directional drilling device for installing underground cables or tubes, comprising a housing having a drill space extending between two openings in sides of the housing for accommodating a drill string through the two openings, and defining a longitudinal drill axis; and a drive mechanism arranged in the housing for engagement with the drill string configured to move the drill string in a drilling direction along the longitudinal drill axis and configured to selectively rotate the drill string about the longitudinal drill axis to perform directional drilling; wherein the drive mechanism comprises a first clamping device for clamping the drill string; wherein the drive mechanism further comprises a second clamping device for clamping the drill string; wherein the first clamping device and the second clamping device are each configured to be arranged in a clamping state, in which the drill string is clamped by the respective clamping device, and in a release state, in which the drill string is movable with respect to the respective clamping device, wherein the drive mechanism is configured to move the clamping devices back and forth along the longitudinal drill axis, and wherein the directional drilling device comprises a control device operatively connected to the drive mechanism and the clamping devices for alternating movement of the clamping devices and for switching the clamping devices between the clamping state and the release state to perform directional drilling.

1 . A directional drilling device for installing underground cables or tubes, comprising:
 a housing having a drill space extending between two openings ( 21 ,  22 ) in sides of the housing for accommodating a drill string through the two openings, and defining a longitudinal drill axis; and   a drive mechanism arranged in the housing for engagement with the drill string configured to move the drill string in a drilling direction along the longitudinal drill axis and configured to selectively rotate the drill string about the longitudinal drill axis to perform directional drilling; wherein the drive mechanism comprises a first clamping device for clamping the drill string;   wherein the drive mechanism further comprises a second clamping device for clamping the drill string;   wherein the first clamping device and the second clamping device are each configured to be arranged in a clamping state, in which the drill string is clamped by the respective clamping device, and in a release state, in which the drill string is movable with respect to the respective clamping device,   wherein the drive mechanism is configured to move the clamping devices back and forth along the longitudinal drill axis, and   wherein the directional drilling device comprises a control device operatively connected to the drive mechanism and the clamping devices for alternating movement of the clamping devices and for switching the clamping devices between the clamping state and the release state to perform directional drilling.   
     
     
         2 . The directional drilling device according to  claim 1 , wherein the directional drilling device comprises a support configured to support the housing, wherein the support positioned with respect to the drill space such that, when the housing is supported by the support, a drill string arranged in the drill space points towards the earth surface at an angle of −45° to 45°, such as −30° to 30° with respect to the horizontal. 
     
     
         3 . The directional drilling device according to  claim 1 , wherein the control device is configured to alternatingly move the first clamping device and the second clamping device in the drilling direction in the clamping state. 
     
     
         4 . The directional drilling device according to  claim 1 , wherein the control device is configured to selectively move the first clamping device and the second clamping simultaneously in the drilling direction in the clamping state. 
     
     
         5 . The directional drilling device according to  claim 1 , wherein a rotation speed with which the drive mechanism rotates the drill string about the longitudinal drill axis is adjustable. 
     
     
         6 . The directional drilling device according to  claim 1 , wherein the drive mechanism comprises a rotational motor to rotate the first clamping device and the second clamping device, wherein the rotational motor is configured:
 to rotate the first clamping device in the clamped state about the drill axis while simultaneously rotating the second clamping device and vice versa,   or   to rotate the first clamping device in the clamped state about the drill axis without rotating the second clamping device and vice versa.   
     
     
         7 . The directional drilling device according to  claim 6 , wherein the drive mechanism comprises a longitudinal actuator attached to the clamping devices and configured to move the clamping devices along the longitudinal drill axis,
 wherein the rotational motor is configured to rotate the longitudinal actuator with the clamping devices.   
     
     
         8 . The directional drilling device according to  claim 7 , wherein the longitudinal actuator comprises a pin, a track or a rod extending parallel to the drill axis and arranged to rotate about the longitudinal drill axis with the clamping devices, wherein the clamping devices are movably attached to the pins, tracks or rods. 
     
     
         9 . The directional drilling device according to  claim 1 , further comprising a bearing configured to align the drill string with the drill axis, wherein the bearing is provided with fluid channels for distributing fluid to the drive mechanism, wherein the fluid channels comprise a stationary port and a rotating port that is rotating with the drill string. 
     
     
         10 . The directional drilling device according to  claim 1 , further comprising an extension piece associated with the housing and configured to be arranged in a guiding position to guide a portion of the drill string that protrudes outside the housing through one of the two openings, to avoid bending of the drill string portion away from the longitudinal drill axis. 
     
     
         11 . A directional drilling assembly, comprising:
 a directional drilling device according to  claim 1 , and   a drill string to be accommodated in the drill space of the directional drilling device, wherein a length of the drill string, for example without drill head, is larger than a length of the drill space, for example wherein the length of a drill string segment is larger than a length of the drill space.   
     
     
         12 . The directional drilling assembly according to  claim 11 , wherein each clamping device delimits an inner clamping diameter, wherein, in the clamping state, the inner clamping diameter is smaller than a diameter of drill string, such that the drill string is locally deformed to improve gripping between clamping device and the drill string. 
     
     
         13 . The directional drilling assembly according to  claim 12 , wherein at least one of the clamping devices is provided with an inner clamping shape that differs from an outer shape of the drill string, such that the drill string is deformed into another, e.g. non-circular shape. 
     
     
         14 . The directional drilling assembly according to  claim 11 , wherein the directional drilling device comprises an interface, such as a remote control, wherein the drill string comprises a drill fluid channel and a tracking device configured to emit a tracking signal, wherein the interface is configured to receive the tracking signal and to display position data representative for a position of the tracking device on the basis of the tracking signal, wherein the tracking device is provided in a tracking device compartment in the drill string, separate from the drill fluid channel. 
     
     
         15 . An attachment for an excavator, such as a mini excavator, comprising a directional drilling device according to  claim 1  or a horizontal drilling assembly according to  claim 11 , and an excavator mount for attaching the directional drilling device to the excavator. 
     
     
         16 . An excavator, comprising the attachment according to  claim 15 , wherein the attachment is provided with a power connection, for example a fluid connection, to the power system, e.g. fluid system, of the mini excavator for powering the drive mechanism. 
     
     
         17 . A method for directional drilling in the ground, comprising the steps of:
 providing a drill string in a directional drilling device, for example wherein a length of the drill string is larger than a length of the directional drilling device;   positioning the device such that the drilling direction reaches the earth surface at a desired angle, for example at an angle of −45° to 45°, such as −30° to 30°, with respect to the horizontal;   clamping the drill string with a first clamping device and moving the first clamping device parallel to a longitudinal drill axis away from an initial position to advance the drill string into the earth;   releasing the first clamping device and clamping the drill string with a second clamping device;   moving the second clamp parallel to the drill axis to further advance the drill string into the earth;   while advancing the drill string, with the first and/or second clamping device, rotating the drill string about the drill axis to advance the drill string along a straight path, and holding the drill string in a fixed rotational position to advance the drill string in a path curved corresponding to the fixed rotational position; and   while advancing the drill string with the second clamp, moving the first clamp back to the initial position, or vice versa, or moving the first clamp and the second clamp together in the clamping state in the drilling direction.   
     
     
         18 . The method according to  claim 17 , wherein a length of the drill string prior to drilling is larger than a length of the directional drilling device. 
     
     
         19 . The method according to  claim 18 , wherein a length of the drill string prior to drilling is the full expected length of the borehole to be drilled in the ground. 
     
     
         20 . The method according to  claim 17 , further comprising the steps of:
 before drilling, digging a starting pit and/or an exit pit with a tool, such as a mini excavator;   optionally, removing a digging device, such as an excavator bucket, from the tool;   attaching a directional drilling device to the tool;   performing the steps of advancing the drill string with the directional drilling device from the starting pit and/or towards the exit pit using the directional drilling device attached to the tool.