Boring or penetrating the earth – Processes – Boring with specific fluid
Patent
1993-11-12
1995-04-25
Neuder, William P.
Boring or penetrating the earth
Processes
Boring with specific fluid
175296, 175135, 175162, 175212, E21B 2108
Patent
active
054090725
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for adjusting rock drilling when drilling a hole by a rock drilling equipment, wherein a rock drilling machine is operated by a combustion engine operated power unit comprising a hydraulic pump operated by a combustion engine for operating the rock drilling machine, and another hydraulic pump for operating a hydraulic-motor-operated compressor producing flushing air for removing drilling mud from the drill hole, and wherein the pressure of pressure fluid to be supplied to a percussion device of the rock drilling machine is adjusted in response to the drilling conditions.
The invention also relates to an arrangement for realizing the method, comprising a rock drilling machine, a combustion-engine operated power unit having a combustion engine, a hydraulic pump operated by it for operating the rock drilling machine, and another hydraulic pump for operating a hydraulic-motor operated compressor producing flushing air.
To drill earth or rock covered by earth or soft rock material, it is customary to use so-called semi-percussion, that is, the pressure level of the percussion machinery is dropped to a lower level in order to save the drilling equipment and to prevent damage. In diesel-hydraulic or other combustion engine operated equipments, this pressure level drop means that the power output of the motor decreases and thus less fuel is needed. Another typical feature of diesel-hydraulic arrangements is that the same motor rotates both the hydraulic pump(s) of the rock drill and the hydraulic pump of a compressor needed for the production of air required for flushing the drill hole. As the rate of rotation of the diesel engine should be kept substantially constant during operation, the operation of the compressor is not affected in any way although the percussion machinery is operated at half power.
A typical problem with an arrangement operating in the known manner is that when the semi-percussion is applied, the earth or rock material is such that additional air would be required although it is not available. As the maximum power of the diesel engine is constant, a larger compressor for producing air cannot be connected to it without decreasing the power available to the rock drill or having to increase the size and power of the diesel engine to an unreasonably high level in view of the normal operation.
The object of the present invention is to provide a method for controlling the amount of flushing air supplied to a rock drilling machine operated by a combustion-engine operated power unit, by means of which method the amount of air can be increased when the power required by the rock drilling machine is below its maximum power. The method according to the invention is characterized in that the hydraulic pump operating the compressor is an adjustable-displacement pump, the volume flow of the pressure fluid supplied by the adjustable-displacement pump being adjustable by a pressure applied to a control conduit of the pump, and that the volume flow of the pressure fluid supplied by the adjustable-displacement pump is adjusted inversely proportionally to the pressure of the pressure fluid supplied to the percussion device of the rock drilling machine so that when the pressure of the pressure fluid of the percussion device decreases at least to a predetermined pressure below a normal pressure value used in the drilling, the volume flow of the pressure fluid supplied by the pump is increased, so that the rate of rotation of the compressor and thus the amount of air supplied by it increases. The arrangement according to the invention is characterized in that the hydraulic pump operating the compressor is an adjustable-displacement pump, the volume flow of the pressure fluid supplied by the pump being adjustable by a pressure acting on a control conduit of the pump, and that the control conduit of the pump of the compressor is arranged to be controlled by a pressure proportional to the pressure of the pressure conduit of the percussion device of the rock drilling machine so that w
REFERENCES:
patent: 4671367 (1987-06-01), Brunsing et al.
Enlund Pentti
Tantarimaki Kari
Neuder William P.
Tamrock Oy
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