DRILLING ROBOT

Abstract

The invention relates to a Drilling robot for drilling a borehole. The drilling robot (2) is purely electrically driven and comprises a movement unit for moving the drilling robot through the borehole, a rotary hammer unit with a drill head (21), a rotating system (22) and a hammering system (23). The rotating system (22) is adapted to rotate the drill head (21) and the hammering system (23) is adapted to hammer with the drill head (21). The hammering system (23) is adapted to operate according to an electro-pneumatic principle in order to generate an electro-pneumatic stroke.

Claims

1. Drilling robot (2) for drilling a borehole (1), wherein the drilling robot (2) is purely electrically driven and comprises a movement unit (4) for moving and stabilizing the drilling robot (2) inside the borehole (1), a rotary hammer unit with a drill head (21), a rotating system (22) and a hammering system (23), wherein the rotating system (22) is adapted to rotate the drill head (21) and wherein the hammering system (23) is adapted to hammer with the drill head (21), characterized in that the hammering system (23) is adapted to operate according to an electro-pneumatic principle in order to generate an electro-pneumatic stroke.

2. Drilling robot (2) according to claim 1, wherein the drilling robot (2) comprises at least one, in particular two, electric motors (27, 31).

3. Drilling robot (2) according to claim 2, wherein a first electric motor (27) of the at least one electric motors (27, 31) drives the rotating system (22) and a second electric motor (31) of the at least one electric motors (27, 31) drives the hammering system (23).

4. Drilling robot (2) according to claim 1, wherein the drilling robot (2) has a cylindrical shape with a diameter (D.sub.1) smaller than 250 mm, in particular smaller than 200 mm, in particular smaller than 150 mm, in particular smaller than 100 mm, in particular smaller than 90 mm.

5. Drilling robot (2) according to claim 3 and 4, wherein the first electric motor (27) and the second electric motor (31) are arranged within the cylindrical shape.

6. Drilling robot (2) according to claim 3 and claim 1, wherein the first electric motor (27) is further away from the drill head (21) than the second electric motor (31).

7. Drilling robot (2) according to claim 6, wherein the torque generated by the first electric motor (27) is transferred from the first electric motor (27) to the drill head (21) via a bypass shaft (29) arranged in longitudinal direction on the side of, in particular parallel to, the second electric motor (31).

8. Drilling robot (2) according to claim 7, wherein the bypass shaft (29) rotates with a frequency higher than 30%, in particular higher than 50%, in particular higher than 100%, of the rotation frequency of the first electric motor (27).

9. Drilling robot (2) according to claim 3 and according to claim 1, wherein the drill head (21) comprises reamers (26) rotating with a frequency at least 10 times, in particular 20 times, lower than the rotation frequency of the first electric motor (27).

10. Drilling robot (2) according to claim 3 and according to claim 1, wherein a gearbox of the rotating system (22) arranged between the drill head (21) and the second electric motor (31) of the hammering system (23) provides a frequency conversion for the rotating system (22) with a conversion factor of at least 8, in particular at least 10, in particular at least 20, in particular at least 40.

11. Drilling robot (2) according to claim 1, wherein the rotating system (22), in particular the gearbox according to claim 10, comprises an epicyclic gear train (30) or a cycloidal drive.

12. Drilling robot (2) according to claim 3 and according to claim 11, wherein the epicyclic gear train (30) or the cycloidal drive is arranged between the drill head (26) and the second electric motor (31).

13. Drilling robot (2) according to claim 11 or according to claim 12, wherein the hammering system (23) generates strokes, and wherein the strokes travel through the sun (33) of the epicyclic gear train (30) to the drill head (21).

14. Drilling robot (2) according to claim 1, wherein the hammering system (23) comprises a piston (32), compressing and expanding air (33) between the piston (32) and a cylindric weight (34) without touching the cylindric weight (34).

15. Drilling robot (2) according to claim 1, comprising a water-based flushing system (8) for flushing cuttings to the surface (5).

16. Drilling robot (2) according to claim 1, wherein the hammering system (23) is adapted to operate with a hammer energy in relation to the diameter (D.sub.1) of the cylindrically shaped drilling robot (2) of at least 0.08 J/mm, in particular of at least 0.1 J/mm, in particular 0.12 J/mm.

17. Drilling robot (2) according to claim 1, wherein the drill head (21) is adapted to operate with a torque in relation to the diameter (D.sub.1) of the cylindrically shaped drilling robot (2) of at least 0.35 Nm/mm, in particular of at least 0.62 Nm/mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention will be better understood and objects other than those set forth above will become apparent from the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:

[0023] FIG. 1 shows a general illustration of a system for drilling a borehole;

[0024] FIG. 2 shows an overview of the drilling robot working inside the borehole;

[0025] FIG. 3a shows the drilling robot from the outside;

[0026] FIG. 3b shows the drilling robot of FIG. 3a, wherein the housing of the drilling robot is not shown;

[0027] FIG. 3c shows a sectional view through the drilling robot.

MODE FOR CARRYING OUT THE INVENTION

[0028] It follows a description of a specific embodiment. The technical data given are merely exemplary and does not limit the scope of the claims.

[0029] FIG. 1 shows a one family house and equipment for drilling a borehole 1. Borehole 1 is drilled in order to heat the house by geothermal energy. The drilling equipment comprises a drilling robot 2 autonomously operating inside the borehole 1. I.e. the drill rig is located directly in the borehole 1 and does not require a drill pipe. The drilling robot 2 is connected with a power and water source via connection 3. A container 4 is arranged on the surface 5 for collecting cuttings from the drilling robot 2. The drilling robot can drill boreholes for geothermal probes up to a depth of at least 250 meters or maximally 500 meters.

[0030] FIG. 2 shows the drilling robot 2 operating inside the borehole 1 in a more detailed view. The drilling robot 2 comprises a drilling unit 3, a movement unit 4 and a control unit 5. Furthermore, a support system (not shown in detail) is arranged inside the borehole 1 following the drilling robot 2.

[0031] The movement unit 4 moves the drilling robot 2 through the borehole 1. While drilling, the movement unit 4 clamps against the drill wall 6 of the borehole 1 in order to absorb all forces of the drilling process. The control unit 5 controls the drilling process of the drilling robot 2 and delivers information to the operating user at the surface 5. The support system supports the drill wall 6. Especially in loose rock, without a support system, rocks, sand, clay etc. would fall into the borehole and cause it to collapse. The support system prevents this.

[0032] A water-based flushing system 8 efficiently flushes cuttings 9 to the surface 5. The water-based flushing system 8 is connected to a water source 10. The flushing is done by a pump 11 that can produce a volume flow of about 5 m.sup.3/h at a pressure of 15 bar. The water is then pumped to the surface 5.

[0033] The water-based flushing system 8 separates the cuttings 9 from the water by a special filter system 12, which reuses the water for flushing. The separated cuttings 9 are stored in container 4. Sensors detect the water level, which allows either water to be added or removed.

[0034] The drilling robot 2 is purely electrically driven and powered by a power source 13. Furthermore, the drilling robot 2 has a cylindrical shape with a diameter D.sub.1 of 80 mm and the borehole 1 has a diameter D.sub.2 of 90 mm.

[0035] FIG. 3a shows the drilling robot 2 from the outside and FIG. 3b shows the drilling robot 2 without the housing 20 sealing the drilling robot 2. FIG. 3c shows a sectional view of the drilling robot 2.

[0036] The drilling robot 2 comprises a rotary hammer unit with a drill head 21, a rotating system 22 and a hammering system 23. The drill head 21 is designed as an overburden system and comprises a pilot bit 25 and three reamers 26. The drill head 21 is rotated by the rotating system 22. Drill head 21 is responsible for demolishing rock and removing cuttings 9 underneath the drill head 21. Therefore, making room for the drilling robot 2 to advance in depth. The rotary hammer unit, including the drill head 21, is designed so that it can be operated in different rock formations by varying the rotary and hammer movement.

[0037] The rotating system 22 comprises a first and upper electric motor 27 which are water-cooled. The first electric motor 27 provides the torque needed to turn the drill head 21 through multiple cylindrical gear pairs 28, a bypass shaft 29 and a planetary gearset 30, also called an epicyclic gear train. A slip clutch 31 then transmits the power to the main shaft 32.

[0038] The first electric motor 27 rotates with a speed of 3k rpm and operates with a power of 0.6 kW. Cylindrical gear pairs 28 convert the rotation of the electric motor 27 to a higher speed of rotation which is further transferred by the bypass shaft 29 to the main shaft 32. With other words, the bypass shaft 29 rotates with a frequency higher than 100% of the rotation frequency of the first electric motor 27. The planetary gearset 30, which is part of a gearbox of the rotating system together with a cylindrical gear pair 36, arranged between the drill head 21 and the second electric motor 31, substantially reduces the rotational speed such that the reamers 26 are operated with a rotational speed of about 100 rpm and a corresponding torque. Reamers 26 rotate with a frequency 30 times lower than the first electric motor 27 and 40 times lower than the bypass shaft 29.

[0039] The hammering system 23 comprises a second and lower electric motor 31. The second electric motor 31 is less far away from the drill head 21 than the first electric motor 27. The second electric motor 31 powers a piston 32 driven by a bevel gear 35. The piston 32 compresses and expands air 33 between itself and a cylindric weight 34 but doesn't touch the cylindric weight 34. Moved by air 33, the cylindric weight 34 hits the main shaft 32 with its kinetic energy several times a second, providing a stroke that travels down to the drill head 21. This principle is called an electro-pneumatic stroke. The main shaft 32 extends through the sun 33 of the planetary gearset 30.

[0040] The second electric motor 31 rotates with a speed of about 13k rpm and operates with a power of about 0.7 kW. The speed of rotation is reduced by the bevel gear 22 such that the piston operates with about 2.5k rpm.

[0041] Finally, the drilling head 21 operates with a torque of 57 Nm, a rotational speed of 100 rpm, a hammer energy of 11 J and with 2.5k strokes per minute.

[0042] The bypass shaft 29 transferring the torque from the first electric motor 27 to the drill head 21 is arranged in longitudinal direction 37 on the side of, in particular parallel to, the second electric motor 31.

[0043] Underneath the impact, a rotary and translational feedthrough of the water-based flushing system 8 is at work. It allows water to enter the flushing channel 8 in the centre of the main shaft 32. The water then travels down to the drill head 21.

[0044] The housing 20 consists of multiple parts that are sealed against outside pressure and held together by metal straps.