DISPOSITIF HYDRAULIQUE DE PERCUSSION

摘要

The percussion device has a working piston (12) movable in a working cylinder (11) and a control piston (25) movable in a control cylinder (24). The control line (34) which leads from the working cylinder (11) into the control cylinder (24) is split up into several branch lines (340 to 347) which open out into the working cylinder (11) in an axially staggered manner. The branch lines lead into a cylinder (37) in which a piston (38) is displaceable. The piston (38) is displaced by a control pressure against the action of a spring (39) and increasingly closes more branch lines with higher control pressure. The control pressure in a control line (43) therefore determines the reversing instant of the control piston (25) during the return stroke of the working piston (12). The percussion frequency and the individual percussion energy can be altered by changing the control pressure. The control pressure is derived from the feed force or the torque of the drilling string (47) or from the supply pressure. <IMAGE>