Reduced-impact sliding pressure control valve for pneumatic hammer drill

United States Patent

8,176,995
May 15, 2012
View the Complete Patent at the US Patent & Trademark Office
Sliding Pressure Control Valve for Pneumatic Hammer Drill
A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.
12/424,583
April 16, 2009
173/114 ; 137/508; 173/13; 173/17; 173/78; 173/79; 173/80; 251/343; 251/344; 251/345; 91/222; 91/327; 91/348;
B25D 9/18 (20060101); B25D 9/00 (20060101);
173/114,13,17,78-80 91/222,327,348 251/343-345 137/508
FEDERALLY SPONSORED RESEARCH The United States Government has rights in this invention pursuant to Department of Energy Contract No. DE-AC04-94AL85000 with Sandia Corporation.