Patent ID: 7096980

Claim:
An impact generating system for applying rotary percussive impacts to a drill bit, the system comprising: an anvil for connection to the bit, a hammer disposed in the anvil for movement about the axis of the anvil in one direction, a device for storing energy in response to the movement of the hammer in the one direction and converting the energy into a force in a direction opposite the first direction for driving the hammer in the opposite direction and against a wall of the anvil to produce the percussive impacts; a fluid flow system for directing fluid against the surface of the hammer to drive the hammer in the one direction; and a rotating disc in the path of the fluid flow and having at least one slot formed therein, so that the disc selectively directs the flow of the fluid against the hammer to cause the hammer to move in the one direction and selectively terminates the flow of the fluid against the hammer to permit the hammer to move in the opposite direction.