Patent ID: 7896100
Filing Date: 2011-03-01
Classification: B25D,E21B

Abstract:
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 (