Patent ID: 7405998

Claim:
An apparatus for generating fluid pressure pulses, comprising: a chamber having an upstream opening, wherein the chamber can collect fluid via the opening, a vent in the chamber, wherein the collected fluid can exit the chamber through the vent, an upstream ported disc coupled to a downstream end of the chamber, wherein the upstream ported disc may rotate about a central axis through its width and wherein the upstream ported disc includes an upstream eccentric port that rotates about the central axis as the upstream ported disc rotates, and a downstream ported disc coupled to a downstream end of the upstream ported disc such that the downstream ported disc remains substantially rotationally fixed relative to the upstream ported disc, wherein the downstream ported disc includes a downstream eccentric port that may align with the upstream eccentric port to form a passageway for fluid to exit from the chamber, through the upstream port, and through the downstream eccentric port to outside of the apparatus, at some time in a rotation cycle of the upstream ported disc.