Valve device for a percussion device and a percussion device for a rock drilling machine

1. Valve device (V, 4 ′) for controlling the movement in a machine housing ( 2 ) of a reciprocating percussion piston ( 3 ) of a percussion device ( 1 ) for a rock drilling machine with a first chamber ( 5 ) that can be pressurized for forward driving of the percussion piston ( 3 ) and a second chamber ( 8 ) that can be pressurized for back-driving of the percussion piston ( 3 ), wherein the valve device includes a to and fro movable valve element ( 20 ), the movement of which being controlled as a response to the position of a valve portion (V) of the percussion piston in a valve housing portion by periodically pressurizing a signal chamber ( 21 ) actuating the movement of the valve element over signal conduit means ( 22 , 23 , 24 ), wherein:

said signal conduit means includes at least two signal conduit portions ( 23 , 24 ), which are arranged for essentially simultaneous pressurizing through co-operation between a corresponding number of valve control edges ( 25 , 26 ) on the valve portion of the percussion piston and a number of edges ( 34 , 35 ) of control chambers in the machine housing, said number of valve control edges and said number of edges of control chambers corresponding to the number of signal conduit portions, said valve control edges of said percussion piston, said at least two signal conduit portions, and said edges of control chambers being arranged such that relative movement between said percussion piston and said machine housing results in said essentially simultaneous pressurizing of said at least two signal conduit portions.

2. Valve device according to claim 1 , wherein said at least two signal conduit portions ( 23 , 24 ) are branched from one conduit ( 22 ), which leads to the signal chamber ( 21 ).

3. Valve device according to claim 2 , wherein a control chamber in the valve housing portion is arranged to co-operate with a valve control edge for fluid contact between each signal conduit portion and a respective pressure conduit portion in a first relative position and with an evacuation conduit portion in a second relative position of the percussion piston in respect to the machine housing ( 2 ).

4. Valve device according to claim 2 , wherein the signal chamber ( 21 ) receives a first piston portion of the valve element ( 20 ) which has a greater pressure actuated surface than a second piston portion, which is received in a chamber ( 33 ) for constant pressurizing.

5. Valve device according to claim 2 , wherein a pressure conduit means ( 27 ), which leads to the valve housing portion (V), includes the same number of pressure conduit portions ( 28 , 29 ) as the number of signal conduit portions ( 23 , 24 ).

6. Valve device according to claim 2 , wherein an evacuation conduit means ( 30 , 31 , 32 ) which leads to the valve housing portion (V), has the same number of evacuation conduit portions ( 31 , 32 ) as the number of signal conduit portions ( 23 , 24 ).

7. Valve device according to claim 1 , wherein a control chamber in the valve housing portion is arranged to co-operate with a valve control edge for fluid contact between each signal conduit potion and a respective pressure conduit portion in a first relative position and with an evacuation conduit portion in a second relative position of the percussion piston in respect to the machine housing ( 2 ).

8. Valve device according to claim 7 , wherein the signal chamber ( 21 ) receives a first piston portion of the valve element ( 20 ) which has a greater pressure actuated surface than a second piston portion, which is received in a chamber ( 33 ) for constant pressurizing.

9. Valve device according to claim 7 , wherein a pressure conduit means ( 27 ), which leads to the valve housing portion (V), includes the same number of pressure conduit portions ( 28 , 29 ) as the number of signal conduit portions ( 23 , 24 ).

10. Valve device according to claim 7 , wherein an evacuation conduit means ( 30 , 31 , 32 ) which leads to the valve housing portion (V), has the same number of evacuation conduit portions ( 31 , 32 ) as the number of signal conduit portions ( 23 , 24 ).

11. Valve device according to claims 1 , wherein the signal chamber ( 21 ) receives a first piston portion of the valve element ( 20 ) which has a greater pressure actuated surface than a second piston portion, which is received in a chamber ( 33 ) for constant pressurizing.

12. Valve device according to claim 11 , wherein a pressure conduit means ( 27 ), which leads to the valve housing portion (V), includes the same number of pressure conduit portions ( 28 , 29 ) as the number of signal conduit portions ( 23 , 24 ).

13. Valve device according to claim 11 , wherein an evacuation conduit means ( 30 , 31 , 32 ) which leads to the valve housing portion (V), has the same number of evacuation conduit portions ( 31 , 32 ) as the number of signal conduit portions ( 23 , 24 ).

14. Valve device according to claim 1 , wherein a pressure conduit means ( 27 ), which leads to the valve housing portion (V), includes the same number of pressure conduit portions ( 28 , 29 ) as the number of signal conduit portions ( 23 , 24 ).

15. Valve device according to claim 14 , wherein the number of signal conduit portions is two, and wherein a control chamber belonging to a pressure conduit portion ( 28 ) is arranged axially in front of, and a control chamber belonging to another pressure conduit portion ( 29 ) is arranged axially behind the respective control chamber belonging to the two signal conduit portions ( 23 , 24 ) as seen in an impact direction of the percussion piston ( 3 ).

16. Valve device according to claim 14 , wherein an evacuation conduit means ( 30 , 31 , 32 ) which leads to the valve housing portion (V), has the same number of evacuation conduit portions ( 31 , 32 ) as the number of signal conduit portions ( 23 , 24 ).

17. Valve device according to claim 1 , wherein an evacuation conduit means ( 30 , 31 , 32 ) which leads to the valve housing portion (V), has the same number of evacuation conduit portions ( 31 , 32 ) as the number of signal conduit portions ( 23 , 24 ).

18. Valve device according to claim 17 , wherein the number of signal conduit portions is two, and wherein the control chambers belonging to the evacuation conduit portions ( 31 , 32 ) are positioned axially between the control chambers of the two signal conduit portions ( 23 , 24 ).

19. Percussion device ( 1 ) for a rock drilling machine with a first chamber ( 5 ) that can be pressurized for forward driving of a percussion piston ( 3 ) and a second chamber ( 8 ) that can be pressurized for back-driving the percussion piston ( 3 ), wherein said percussion device includes a valve device according to claim 1 .

20. Rock drilling machine including a percussion device according to claim 19 .