Rotary-percussive hydraulic perforator provided with a control chamber permanently connected to a low-pressure accumulator

A rotary percussive hydraulic perforator comprising:

• a body,
• a fitting intended to be coupled to at least one drilling bar equipped with a tool,
• a striking piston slidably mounted inside the body along a striking axis and configured to strike the fitting,
• a stop piston which is slidably mounted in a cavity of the body along an axis of displacement substantially parallel to the striking axis, the stop piston including a front face facing the fitting and intended to position the fitting in a predetermined equilibrium position with respect to the striking piston, and a rear face opposite to the front face and situated opposite to a rear wall of the cavity, and
• a main hydraulic supply circuit configured to control an alternating sliding of the striking piston along the striking axis and to control a sliding of the stop piston along the axis of displacement, the main hydraulic supply circuit including a high pressure fluid supply conduit and a low pressure fluid return conduit,
• the body and the stop piston delimiting at least partially a first control chamber permanently connected to the high pressure fluid supply conduit and configured to bias the stop piston forwards, the rotary percussive hydraulic perforator further comprising a connecting channel configured to fluidly connect the first control chamber to the low pressure fluid return conduit when the rear face of the stop piston is located at a distance from the rear wall of the cavity which is greater than a predetermined value, wherein the main hydraulic supply circuit further includes a low pressure accumulator connected to the low pressure fluid return conduit, and in that the body and the stop piston further delimit at least partially a second control chamber permanently connected to the low pressure accumulator and configured to bias the stop piston forwards.