Fluid-actuated drilling tool

Claim 1

IN A FLUID-ACTUATED PERCUSSION DRILLING TOOL WHICH INCLUDES IN COMBINATION AN OUTER CASING, AN ANVIL SLIDABLY SECURED WITHIN THE LOWER END OF SAID CASING AND ADAPTED TO SUPPORT A DRILL BIT, SAID ANVIL HAVING A FLOW PASSAGE TO CONDUCT DRILLING FLUID TO SAID BIT, AND A HAMMER ELEMENT SLIDABLY POSITIONED WITHIN SAID OUTER CASING ABOVE SAID ANVIL AND ADAPTED TO DELIVER PERCUSSIVE BLOWS TO THE UPPER END OF SAID ANVIL, SAID HAMMER ELEMENT HAVING AT LEAST ONE FLUID FLOW PASSAGE TO CONDUCT FLUID THROUGH SAID ELEMENT TO THE LOWER END THEREOF AND A CHAMBER OPENING THROUGH THE LOWER END OF AND INTERCONNECTING WITH SAID FLOW PASSAGE IN SAID ELEMENT, THE IMPROVEMENT WHICH COMPRISES A UNITARY VALVE STRUCTURE SLIDABLY POSITIONED WITHIN SAID CHAMBER IN SAID HAMMER ELEMENT, SAID VALVE STRUCTURE HAVING AN UPPER SOLID PORTION AND FLUID FLOW PORTS ADAPTED TO COACT AT ALTERNATE SLIDABLE POSITIONS WITH SAID FLUID FLOW PASSAGE WITHIN SAID HAMMER ELEMENT TO CONTROL THE FLOW OF DRILLING FLUID THROUGH SAID HAMMER ELEMENT, SAID VALVE STRUCTURE BEING FURTHER PROVIDED WITH A LOWER SOLID PORTION EXTENDABLE BELOW SAID HAMMER ELEMENT AT ONE POSITION OF SAID VALVE STRUCTURE TO COACT WITH SAID FLOW PASSAGE IN SAID ANVIL TO CONTROL THE FLOW OF DRILLING FLUID THROUGH SAID ANVIL.