A highly responsive valve for exhausting high pressure combustion gases from a closed combustion chamber upon the occurrence of a predetermined pressure is disclosed. A valve housing defines a cylindrical pressure chamber adapted for connection to a combustion chamber. A cylindrical valve sleeve is reciprocably guided along the chamber interior wall from a first position blocking directionally oriented outlet ports in the chamber to a second position opening the outlet ports to rapidly discharge combustion gases from the pressure chamber. The lower edge of the sleeve seats against a cover plate in the first position and defines an annular pressure chamber with the grooved seat. A pilot valve houses a reciprocable piston which controls communication between the pressure chamber and the valve chamber. The pilot valve piston is pressure biased to a position blocking communication between the pressure and valve chambers and the pilot valve piston shifts in response to a predetermined pressure rise in the valve pressure chamber to communicate the annular pressure chamber with high pressure to cause the valve sleeve to be rapidly accelerated to a full open position. Ring springs limit the sleeve travel and absorb the energy of the accelerating sleeve. The valve sleeve is provided with an internal shoulder area exposed to the pressure chamber so that combustion chamber pressure prior to ignition acts to positively hold the sleeve seated. Lubricating fluid is introduced in a valve guided slot of the valve sleeve and valve housing wall surfaces so that lubricant is prevented from entering the interior pressure chamber.
Charles D. Wood