Method and system for controlling a power source at a rock drilling apparatus and rock drilling apparatus

1. Method for controlling a power source at a rock drilling apparatus, said power source being arranged to drive at least a first load at the rock drilling apparatus, wherein said first load in operation, provides power to a first consumer, and where the power that can be delivered by said first load depends on the rotation speed of the power source, the method including:

by means of a representation of said first consumer, determining a power demand of said first consumer,

based on said determined power demand, determining a rotation speed demand of said first load, wherein, when determining a rotation speed demand of said first load based on a determined power demand, a determined relation between the rotation speed of the power source and the power that can be delivered by said first load is used, and

controlling the rotation speed of said power source based at least on said determined rotation speed demand of said first load.

2. Method according to claim 1 , wherein said power source is arranged to drive at least one second load at the rock drilling apparatus, where said second load, in operation, provides power to a second consumer, and where the power that can be delivered by said second load depends on the rotation speed of the power source, the method further including:

determining a second power demand of said second consumer,

determining a second speed demand of said second load based on said second power demand, and

controlling the rotation speed of the power source based on the speed demands of said first and second loads.

3. Method according to claim 2 , wherein said second power demand of said second consumer is determined by means of a representation of said second consumer.

4. Method according to claim 3 , wherein the method further includes setting the rotation speed of the power source to the highest of the rotation speed demands that has been determined for said first and second loads.

5. Method according to claim 2 , wherein the method further includes setting the rotation speed of the power source to the highest of the rotation speed demands that has been determined for said first and second loads.

6. Method according to claim 2 , wherein the rotation speed of the power source can be set to a plurality of fixed rotation speeds, wherein the method further includes setting the rotation speed of the power source to the fixed rotation speed that is closest above the highest of the rotation speed demands that has been determined for said first and second loads.

7. Method according to claim 2 , wherein the rotation speed of the power source can be set to a plurality of fixed rotation speeds, wherein the method further includes setting the rotation speed of the power source to a fixed rotation speed that is at most 10% above or below the highest of the rotation speed demands that has been determined for said first and second loads.

8. Method according to claim 1 , wherein the power source consists of a combustion engine, where the rotation speed of the combustion engine is set to idling speed when said determined rotation speed demand is lower than the idling speed of the combustion engine.

9. Method according to claim 1 , wherein the method further includes communicating said determined rotation speed demand of said first consumer from control means of said first consumer to control means of said first load.

10. Method according to claim 1 , wherein said first consumer is used during rock drilling processes percussion and rotation.

11. Method according to claim 1 , wherein said method is performed automatically by a control system of said rock drilling apparatus.

12. System for controlling a power source at a rock drilling apparatus, where said power source is arranged to drive at least a first load at the rock drilling apparatus, where said first load, in operation, is arranged to provide power to a first consumer, and where the power that can be delivered by said first load depends on the rotation speed of the power source, wherein the system includes:

determination means for determining a power demand of said first consumer by means of a representation of said first consumer,

determination means for determining a rotation speed demand of said first load based on said determined power demand, wherein, when determining a rotation speed demand of said first load based on a determined power demand, a determined relation between the rotation speed of the power source and the power that can be delivered by said first load is used, and

control means for controlling the rotation speed of said power source based at least on said determined rotation speed demand of said first load.

13. System according to claim 12 , wherein said power source is arranged to drive at least one second load at the rock drilling apparatus, where said second loads, in operation, is arranged to provide power to a second consumer, and where the power that can be delivered by said second load depends on the rotation speed of the power source, the system further including:

determination means for determining a power demand of said second consumer,

determination means for determining a speed demand of said second load based on said determined power demand, and

control means for controlling the rotation speed of the power source based on the speed demands of said first and second load.

14. System according to claim 12 , wherein said representation of said first consumer consists of a software representation of said first consumer.

15. System according to claim 12 , wherein an input shaft of said first load is arranged to be driven by an output shaft of said power source such that the rotation speed of the load is linearly dependent on the rotation speed of the power source.

16. System according to claim 12 , wherein said at least first load consists of a hydraulic pump, and the power demand of said at least first consumer consists of a hydraulic flow demand.

17. System according to claim 12 , wherein said control means consists of a control unit or a dedicated computer program code in a control unit.

18. System according to claim 12 , wherein the system further includes means for reducing the power provided to a consumer when the load being associated with said consumer is driven at a higher speed than said determined rotation speed demand.

19. Rock drilling apparatus, wherein said apparatus includes a system according to claim 12 .