Drilling tool with feed control

1. A downhole drilling tool for drilling in a drilling direction in a downhole valve or a formation downhole, comprising:

a drilling head having at least one drill bit and being in connection with a first portion of the tool,

a driving unit for driving the drilling head and the first portion forward in a longitudinal movement while drilling, the driving unit being in connection with a second portion of the tool, and

a fixating device in connection with the second portion for abutment of the tool against the downhole valve or the formation downhole and for fixation of the tool when drilling, wherein the tool further comprises a feed control inside the tool for controlling the longitudinal movement of the drilling head in the downhole valve or the formation downhole by controlling a movement of the first portion in relation to the second portion of the tool, wherein the feed control comprises:

the second portion fixedly provided within the tool wherein the first and second portion together form a first fluid chamber,

a second fluid chamber in fluid connection with the first fluid chamber, and

a fluid control means for controlling a rate of fluid passing from one chamber to the other for controlling the longitudinal movement of the drilling head in relation to the drilling tool,

wherein the fixating device is situated in front of the tool in the drilling direction for abutment of the tool against the downhole valve in front of the tool or the formation downhole in front of the tool.

2. The downhole drilling tool according to claim 1 , wherein the first or the second portion is a piston sliding within the other portion functioning as a piston housing.

3. The downhole drilling tool according to claim 2 , wherein the feed control further comprises a return valve for letting fluid from the second fluid chamber back into the first fluid chamber, thereby returning the piston to its initial position when the drilling stops.

4. The downhole drilling tool according to claim 2 , wherein the first fluid chamber has at least one spring means in the first fluid chamber for forcing the piston to return to its initial position when the drilling stops.

5. The downhole drilling tool according to claim 2 , wherein the fluid control means are inside the piston housing.

6. The downhole drilling tool according to claim 1 , wherein the fluid control means is a throttle valve for providing a controlled fluid flow from the first fluid chamber to the second fluid chamber.

7. The downhole drilling tool according to claim 1 , wherein the fixating device has a cylindrical, encircling wall surrounding the drill bit when the drill bit is in its initial position before drilling.

8. A downhole drilling tool for drilling in a drilling direction in a downhole valve or a formation downhole, comprising:

a drilling head having at least one drill bit and being in connection with a first portion of the tool,

a driving unit for driving the drilling head and the first portion forward in a longitudinal movement while drilling, the driving unit being in connection with a second portion of the tool, and

a fixating device in connection with the second portion for abutment of the tool against the downhole valve or the formation downhole and for fixation of the tool when drilling, wherein the tool further comprises a feed control inside the tool for controlling the longitudinal movement of the drilling head in the downhole valve or the formation downhole by controlling a movement of the first portion in relation to the second portion of the tool, wherein the feed control comprises:

the second portion fixedly provided within the tool wherein the first and second portion together form a first fluid chamber,

a second fluid chamber in fluid connection with the first fluid chamber, and

a fluid control means for controlling a rate of fluid passing from one chamber to the other for controlling the longitudinal movement of the drilling head in relation to the drilling tool,

wherein the fixating device has a cylindrical, encircling wall surrounding the drill bit when the drill bit is in its initial position before drilling.

9. The downhole drilling tool according to claim 8 , wherein the first or the second portion is a piston sliding within the other portion functioning as a piston housing.

10. The downhole drilling tool according to claim 9 , wherein the fluid control means are inside the piston housing.

11. The downhole drilling tool according to claim 8 , wherein the feed control further comprises a return valve for letting fluid from the second fluid chamber back into the first fluid chamber, thereby returning the piston to its initial position when the drilling stops.

12. The downhole drilling tool according to claim 8 , wherein the fluid control means is a throttle valve for providing a controlled fluid flow from the first fluid chamber to the second fluid chamber.

13. The downhole drilling tool according to claim 8 , wherein the first fluid chamber has at least one spring means in the first fluid chamber for forcing the piston to return to its initial position when the drilling stops.

14. The downhole drilling tool according to claim 8 , wherein the fixating device is situated in front of the tool in the drilling direction for abutment of the tool against the surroundings in front of the tool.

15. A downhole drilling tool for drilling in a drilling direction in a downhole valve or a formation downhole, comprising:

a drilling head having at least one drill bit and being in connection with a first portion of the tool,

a driving unit for driving the drilling head and the first portion forward in a longitudinal movement while drilling, the driving unit being in connection with a second portion of the tool, and

a fixating device in connection with the second portion for abutment of the tool against the downhole valve or the formation downhole and for fixation of the tool when drilling, wherein the tool further comprises a feed control inside the tool for controlling the longitudinal movement of the drilling head in the downhole valve or the formation downhole by controlling a movement of the first portion in relation to the second portion of the tool, wherein the feed control comprises:

the second portion fixedly provided within the tool wherein the first and second portion together form a first fluid chamber,

a second fluid chamber in fluid connection with the first fluid chamber, and

a fluid control means for controlling a rate of fluid passing from one chamber to the other for controlling the longitudinal movement of the drilling head in relation to the drilling tool;

wherein the first or the second portion is a piston sliding within the other portion functioning as a piston housing, and

wherein the fluid control means are inside the piston housing.

16. The downhole drilling tool according to claim 15 , wherein the feed control further comprises a return valve for letting fluid from the second fluid chamber back into the first fluid chamber, thereby returning the piston to its initial position when the drilling stops.

17. The downhole drilling tool according to claim 16 , wherein the first fluid chamber has at least one spring means in the first fluid chamber for forcing the piston to return to its initial position when the drilling stops.

18. The downhole drilling tool according to claim 15 , wherein the fluid control means is a throttle valve for providing a controlled fluid flow from the first fluid chamber to the second fluid chamber.

19. The downhole drilling tool according to claim 15 , wherein the fixating device is situated in front of the tool in the drilling direction for abutment of the tool against the surroundings in front of the tool.

20. The downhole drilling tool according to claim 15 , wherein the fixating device has a cylindrical, encircling wall surrounding the drill bit when the drill bit is in its initial position before drilling.