Spark arrester and silencer

Claim 1

A spark arrester and silencer comprising: a core comprising a tube having an upstream portion and a downstream portion, the tube being open at its downstream end for the outlet of gas, said tube having a plurality of sets of longitudinally spaced openings, said sets being annularly spaced apart, at least one set of said openings being positioned in said upstream portion of said tube, and at least one set of said openings being positioned in said downstream portion of said tube; means closing the upstream end of said tube against the entrance of gases; a fine mesh screen disposed about said tube to cover said openings; a first cylindrical conduit about said upstream portion of said tube, said first conduit having a greater interior diameter than the exterior diameter of said tube and screen, to form a first annular passageway between the upstream portion of said tube and said first conduit, the downstream end of said first conduit being open, and terminating adjacent the downstream portion of said tube; said means closing the upstream end of said tube further comprises a generally conical deflector connected to the end of the first conduit adjacent said closed end of said tube, the apex of said deflector being adjacent the inlet of the spark arrester and silencer; a shell in which the core is disposed, said shell having an upstream portion and a downstream portion, the inside diameter of said shell being substantially greater than the outside diameter of said first conduit of the core, to form a second annular passageway between the upstream portion of said shell and said first conduit, said shell extending beyond the open end of the first conduit to substantially the downstream end of said tube; whereby said upstream portion of said tube, said first conduit, and said upstream portion of said shell coact to define a first upstream muffler section, said first muffler section and said deflector causing gas to flow longitudinally along said second annular passageway, to reverse flow along said first annular passageway, to traverse said screen and openings of said upstream portion of said tube, to flow in the original direction along said tube, and to exit at the downstream end of the said tube; a second cylindrical conduit positioned about said downstream portion of said tube, said second conduit having a greater interior diameter than the exterior diameter of said tube and screen, to form a third annular passageway between the downstream portion of said tube and said second conduit, the downstream end of said second conduit being open, and terminating at substantially the downstream end of said tube, said second conduit having its upstream end closed by attachment to the exterior of said tube at said upstream portion thereof; the inside diameter of said shell being substantially greater than the outside diameter of said second conduit, to form a fourth annular passageway between the downstream portion of said shell and said second conduit; the upstream end of said shell tapering inwardly and terminating in an inlet for gases, the tapered portion of said shell forming a chamber; means providing a seal between the downstream end of said shell and the downstream end of said tube, said sealing means being spaced from the downstream end of said second conduit; whereby said downstream portion of said tube, said second conduit, and said downstream portion of said shell coact to define a second downstream muffler section, said second muffler section, said deflector, and said sealing means causing gas to flow longitudinally along said fourth annular passageway, to reverse flow along said third annular passageway, to traverse said screen and openings of said downstream portion of said tube, to flow in the original direction along said tube, to comingle with the gas from said first muffler section, and to exit at said downstream end of said tube; said first and second muffler sections being similar in structure and function, being longitudinally separated, and being substantially aligned and coaxial.