Pneumatic tool having exhaust noise reducing means

Claim 1

IN A PNEUMATIC TOOL A GENERALLY CYLINDRICAL HOUSING, A ROTARY AIR MOTOR MOUNTED WITHIN SAID HOUSING, A CYLINDRICAL EXTERNAL SURFACE ON SAID HOUSING WITH ONE END THEREOF TERMINATING IN AN ANNULAR SHOULDER RADIALLY OUTWARDLY OF SAID SURFACE, AIR EXHAUST PASSAGES LONGITUDINALLY DISPOSED WITHIN THE HOUSING CONNECTING THE OUTLET SIDE OF SAID AIR MOTOR WITH THE END OF SAID EXTERNAL SURFACE ADJACENT SAID SHOULDER, A SLEEVE EXTENDING FROM SAID SHOULDER IN SUBSTANTIALLY PARALLEL SPACED RELATION TO SAID EXTERNAL SURFACE, OPENING MEANS IN SAID SLEEVE COMMUNICATING DIRECTLY WITH THE ATMOSPHERE AT THE END OF SAID SLEEVE OPPOSITE TO SAID SHOULDER, A PLURALITY OF NOISE REDUCING RINGS OF RELATIVELY RIGID POROUS MATERIAL MOUNTED IN AXIALLY STACKED RELATION BETWEEN SAID EXTERNAL SURFACE AND SAID SLEEVE FOR SUPPORTING SAID SLEEVE AROUND SAID SURFACE AND FOR REDUCING THE NOISE OF THE EXHAUST AIR ISSUING FROM SAID EXHAUST PASSAGES THROUGH SAID SLEEVE TO THE ATMOSPHERE, AND MEANS IN SAID SLEEVE FOR KEEPING SAID RINGS AXIALLY SPACED THEREIN UNDER THE FORMATION OF A SUBSTANTIALLY ANNULAR EXPANSION CHAMBER FOR THE EXHAUST AIR ADJACENT AT LEAST ONE OF THE AXIAL FACES OF EACH RING IN SAID SLEEVE FOR INCREASING THE NOISE REDUCTION THEREIN.