Percussion tool

Claim 1

A PERCUSSION TOOL FOR A ROTARY DRILL BIT MOUNTED ON THE LOWER END OF A ROTARY DRILL PIPE INCLUDING A HOUSING CONNECTED IN THE DRILL PIPE ADJACENT THE DRILL BIT AND HAVING A PASSAGE FOR CONDUCTING DRILLING FLUID FROM SAID PIPE TO SAID BIT, AN UPWARDLY FACING VALVE SEAT AT THE LOWER PORTION OF THE PASSAGE OF THE HOUSING, A VALVE MEMBER IN SAID HOUSING PASSAGE ABOVE THE VALVE SEAT AND MOVABLE BY THE FLOW OF THE DRILLING FLUID THROUGH SAID PASSAGE INTO ENGAGEMENT WITH SAID SEAT TO HALT SAID FLOW WHEREBY THE INERTIA OF SAID FLUID IMPARTS A DOWNWARD IMPACT TO SAID DRILL BIT, A TUBULAR BARREL MOUNTED IN SAID PASSAGE ABOVE SAID VALVE SEAT IN SPACED RELATION TO SAID HOUSING AND HAVING A CLOSED UPPER END AND AN OPEN LOWER END COMMUNICATING WITH SAID PASSAGE, A PISTON RECIPROCABLY MOUNTED IN THE BARREL AND HAVING ITS LOWER END EXPOSED TO THE FLUID IN SAID PASSAGE WHEREBY THE PISTON IS MOVABLE UPWARDLY BY THE PRESSURE OF SAID FLUID WHEN THE VALVE MEMBER IS SEATED, STOP MEANS IN SAID BARREL UNDERLYING SAID PISTON, FIRST RESILIENT MEANS FOR URGING SAID PISTON DOWNWARDLY INTO ENGAGEMENT WITH THE STOP MEANS, A MANDREL UPSTANDING FROM SAID VALVE MEMBER SO AS TO BE MOVABLE THEREWITH AND SLIDABLY SUPPORTED BY SAID PISTON WHEREBY SAID VALVE MEMBER IS UNSEATED BY UPWARD MOVEMENT OF SAID PISTON, SECOND RESILIENT MEANS BETWEEN PORTIONS OF THE MANDREL AND PISTON FOR SUPPORTING SAID MANDREL IN COACTION WITH SAID PISTON, THE SECOND RESILIENT MEANS URGING SAID MANDREL UPWARDLY RELATIVE TO SAID PISTON TO UNSEAT SAID VALVE MEMBER AND PERMITTING RELATIVE DOWNWARD MOVEMENT OF SAID MANDREL AND SEATING OF SAID VALVE MEMBER, SAID SECOND RESILIENT MEANS BEING COMPRESSED BY UPWARD MOVEMENT OF SAID PISTON RELATIVE TO SAID MANDREL WHEREBY SAID VALVE MEMBER REMAINS SEATED DURING INITIAL UPWARD MOVEMENT OF SAID PISTON, AND SPRING PRESSED UPWARDLY SEATING VALVE MEANS AT THE LOWER END OF SAID BARREL IN SURROUNDING RELATION TO SAID MANDREL FOR RESTRICTING THE UPWARD FLOW OF FLUID FROM SAID PASSAGE INTO SAID BARREL TO RETARD UPWARD MOVEMENT OF SAID PISTON AND UNSEATING OF SAID VALVE MEMBER AND FOR PERMITTING SUBSTANTIALLY UNRESTRICTED DOWNWARD FLOW FROM SAID BARREL TO SAID PASSAGE UPON UNSEATING OF SAID VALVE MEMBER WHEREBY SAID PISTON IS RAPIDLY REENGAGED WITH SAID STOP MEANS BY THE FORCE OF THE FIRST RESILIENT MEANS.