Muffler with reed valve providing continuous venting

Claim 2

A muffler for an internal combustion engine comprising: a housing defining an exhaust gas flow path for communicating with an exhaust port of the engine and an exhaust outlet opening for communicating with the surrounding atmosphere, said outlet opening having an area in the range of about 0.25 to 1.25 square inches; a flexible, elongate, reed spring; attaching means for fixedly anchoring said elongate reed spring adjacent one end thereof with said reed supported in cantilever fashion externally of said housing and with the other end thereof normally blocking, in a reed-closed position, a portion of the area of said outlet opening in the range of about 55 percent to about 85 percent, the remainder of the area of said outlet opening providing continuous communication between said exhaust gas flow path and the atmosphere surrounding aid housing; said reed being deflectable to a reed open position in response to exhaust gases passing through said exhaust outlet opening.

Claim 3

The muffler according to claim 1 wherein: said other end of said reed is provided with at least one aperture disposed over said exhaust outlet opening; and wherein said remainder of the area of said exhaust outlet opening communicates with the atmosphere through said reed aperture.

Claim 4

The muffler according to claim 2 wherein: said exhaust outlet opening and said at least one reed aperture are generally circular and generally concentric with said reed in a reed-closed position.

Claim 5

The muffler according to claim 1 wherein: said exhaust outlet opening is defined by a scalloped periphery; and wherein said remainder of the area of said exhaust outlet opening is defined between a portion of said scalloped periphery and a portion of the edges of said reed spring.

Claim 6

The muffler according to claim 1 wherein: said other end of said reed spring is provided with a generally straight edge extending generally transversely of the longitudinal extent of said reed spring; and wherein said remainder oF the area of said exhaust outlet opening is defined between the periphery of said exhaust outlet opening and said generally straight edge.

Claim 7

The muffler according to claim 5 wherein: said generally straight edge is inclined with respect to the longitudinal extent of said reed spring.

Claim 8

The muffler according to claim 5 further comprising: a cup-shaped spark arrestor seated in said exhaust outlet.

Claim 9

The muffler according to claim 1 wherein said reed is provided with a generally arcuate tip, and wherein said outlet opening is polygonal; said remainder of the area of said outlet opening being defined by said arcuate tip on opposite sides of the reed at the forward end of said exhaust outlet opening.

Claim 10

In combination with an internal combustion engine having a displacement in the range of about 2 to 8 cubic inches and including an exhaust port, a muffler comprising: a housing defining an expansion chamber having a volume in the range of about 2 to 40 cubic inches; said expansion chamber defining an exhaust inlet communicating with said exhaust port of said engine and an exhaust outlet opening communicating with the surrounding atmosphere; said exhaust outlet opening having an area in the range of about 0.25 to 1.25 square inches; a flexible, elongate, reed spring; attaching means for fixedly anchoring said elongate reed spring adjacent one end thereof with said reed spring supported in cantilever fashion externally of said housing and with the other end thereof normally blocking in a reed closed position, a portion of the area of said exhaust outlet opening in the range of about 55 percent to about 85 percent, the remainder of the area of said outlet opening providing continuous communication between said expansion chamber and the atmosphere surrounding said housing; said reed spring being deflectable to a reed open position in response to the application of force in the range of about 1 to 10 pounds by exhaust gases passing through said exhaust outlet opening; and the exhaust being provided in a pressure range of about 1 to 10 p.s.i.

Claim 11

In combination with an internal combustion engine having a displacement in the range of about 2 to 8 cubic inches and including an exhaust port, a muffler comprising: a housing defining an expansion chamber having a volume in the range of about 2 to 40 cubic inches; said expansion chamber defining an exhaust inlet communicating with said exhaust port of said engine and an exhaust outlet opening communicating with the surrounding atmosphere; said exhaust outlet opening having an area in the range of about 0.25 to 1.25 square inches; a flexible, elongate, reed spring; attaching means for fixedly anchoring said elongate reed spring adjacent one end thereof with said reed spring supported in cantilever fashion externally of said housing and with the other end thereof normally blocking in a reed closed position, a portion of the area of said exhaust outlet opening in the range of about 55 percent to about 85 percent, the remainder of the area of said outlet opening providing continuous communication between said expansion chamber and the atmosphere surrounding said housing; said reed spring being deflectable to a reed open position in response to the application of force in the range of about 1 to 10 pounds by exhaust gases passing through said exhaust outlet opening; and the exhaust being provided in a pressure range of about 1 to 10 p.s.i.

Claim 12

In combination with a chain saw driven by an internal combustion engine, a muffler mounted on said chain saw and comprising: a rigid housing defining an expansion chamber and having at least one generally flat, planar outer surface, said expansion chamber including: an exhaust inlet for communicating with an exhaust port of the engine, and an exhaust outlet opening to said generally flat outer surface and operationally displaced from alignment with said exhaust inlet; a flexible, elongate and generally flat spring reed; and cantilever support means for fixedly anchoring said reed to said housing adjacent one end of said reed with the major portion of said reed being normally supported, in a closed portion of said reed, on said generally flat outer surface and with the portion of said reed remote from said one end blocking a major portion of said exhaust outlet while a minor portion of said exhaust outlet is in continuous communication between said expansion chamber and the atmosphere surrounding said housing; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said support means; and said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 13

In combination with a chain saw driven by an internal combustion engine, a muffler mounted on said chain saw and comprising: a rigid housing defining an expansion chamber and having at least one generally flat, planar outer surface, said expansion chamber including: an exhaust inlet for communicating with an exhaust port of the engine, and an exhaust outlet opening to said generally flat outer surface and operationally displaced from alignment with said exhaust inlet; a flexible, elongate and generally flat spring reed; and cantilever support means for fixedly anchoring said reed to said housing adjacent one end of said reed with the major portion of said reed being normally supported, in a closed portion of said reed, on said generally flat outer surface and with the portion of said reed remote from said one end blocking a major portion of said exhaust outlet while a minor portion of said exhaust outlet is in continuous communication between said expansion chamber and the atmosphere surrounding said housing; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said support means; and said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 14

A muffler for an internal combustion engine comprising: a rigid housing defining an expansion chamber and having at least one generally flat, planar outer surface, said expansion chamber including: an exhaust inlet for communicating with an exhaust port of the engine, and an exhaust outlet opening to said generally flat outer surface and operationally displaced from alignment with said exhaust inlet; a flexible, elongate and generally flat spring reed having a length dimension greater than its width dimension; and cantilever support means for fixedly anchoring said reed to said housing adjacent one end of said reed with the major portion of said reed being normally supported, in a closed position of said reed, on said generally flat outer surface and with the portion of said reed longitudinally remote from said one end blocking a major portion of said exhaust outlet while a minor portion of said exhaust provides continuous communication between said expansion chamber and the atmosphere surrounding said housing; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said cantilever support means; and said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 15

A muffler for an internal combustion engine comprising: a rigid housing defining an expansion chamber and having at least one generally flat, planar outer surface, said expansion chamber including: an exhaust inlet for communicating with an exhaust port of the engine, and an exhaust outlet opening to said generally flat outer surface and operationally displaced from alignment with said exhaust inlet; a flexible, elongate and generally flat spring reed having a length dimension greater than its width dimension; and cantilever support means for fixedly anchoring said reed to said housing adjacent one end of said reed with the major portion of said reed being normally supported, in a closed position of said reed, on said generally flat outer surface and with the portion of said reed longitudinally remote from said one end blocking a major portion of said exhaust outlet while a minor portion of said exhaust provides continuous communication between said expansion chamber and the atmosphere surrounding said housing; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said cantilever support means; and said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 16

A muffler for an internal combustion engine comprising: a housing defining an exhaust gas flow path having an exhaust inlet for communicating with an exhaust port of the engine and an exhaust outlet for communicating with the surrounding atmosphere, said exhaust inlet and said exhaust outlet being operationally displaced from alignment with one another so that said exhaust gas flow path is tortuously defined; a flexible, elongate and generally flat spring reed having a length dimension greater than its width dimension; support means including anchor means fixedly anchoring said reed adjacent one longitudinal end thereof and including a generally flat planar support surface for normally supporting a major portion of said reed in a closed reed position; the end portion of said reed longitudinally remote from said one end blocking a major portion of said exhaust outlet while a minor portion of said exhaust outlet provides continuous communication between said exhaust gas flow path and the surrounding atmosphere; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said anchor means; and said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 17

A muffler for an internal combustion engine comprising: a housing defining an exhaust gas flow path having an exhaust inlet for communicating with an exhaust port of the engine and an exhaust outlet for communicating with the surrounding atmosphere, said exhaust inlet and said exhaust outlet being operationally displaced from alignment with one another so that said exhaust gas flow path is tortuously defined; a flexible, elongate and generally flat spring reed having a length dimension greater than its width dimension; support means including anchor means fixedly anchoring said reed adjacent one longitudinal end thereof and including a generally flat planar support surface for normally supporting a major portion of said reed in a closed reed position; the end portion of said reed longitudinally remote from said one end blocking a major portion of said exhaust outlet while a minor portion of said exhaust outlet provides continuous communication between said exhaust gas flow path and the surrounding atmosphere; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said anchor means; and said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 18

A muffler for an internal combustion engine comprising: a housing defining an exhaust gas flow path having an exhaust inlet for communicating with an exhaust port of the engine and an exhaust outlet communicating with the surrounding atmosphere; a flexible elongate reed spring; means for fixedly anchoring said reed spring adjacent one reed spring end, with the end portion of said reed spring remote from said one end blocking, in a reed-closed position, a major portion of said exhaust outlet, while a minor portion of said exhaust outlet remains in continuous communication with the surrounding atmosphere through a venting flow path bounded by at least one of said reed spring and said exhaust outlet; said venting flow path being at least partially bounded by a generally curved peripheral boundary; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said one end thereof; said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 19

A muffler for an internal combustion engine comprising: a housing defining an exhaust gas flow path having an exhaust inlet for communicating with an exhaust port of the engine and an exhaust outlet communicating with the surrounding atmosphere; a flexible elongate reed spring; means for fixedly anchoring said reed spring adjacent one reed spring end, with the end portion of said reed spring remote from said one end blocking, in a reed-closed position, a major portion of said exhaust outlet, while a minor portion of said exhaust outlet remains in continuous communication with the surrounding atmosphere through a venting flow path bounded by at least one of said reed spring and said exhaust outlet; said venting flow path being at least partially bounded by a generally curved peripheral boundary; said reed being deflectable to an open position by the force of exhaust gases passing through said exhaust outlet and acting on said reed to deflect said reed about said one end thereof; said minor portion of said exhaust outlet being of a magnitude to continuously vent an amount of exhaust gas sufficient to avoid substantial flutter of said reed during engine idle and to avoid substantial floating of said reed during engine operation.

Claim 20

The muffler according to claim 13 wherein: said geNerally curved peripheral boundary is provided by an aperture in said remote end of said reed spring.

Claim 21

The muffler according to claim 14 wherein: said aperture and said exhaust outlet are each generally circular and generally axially aligned.

Claim 22

The muffler according to claim 13 wherein: said curved peripheral boundary is provided at least in part by said exhaust outlet, said exhaust outlet being generally circular.

Claim 23

The muffler according to claim 16 wherein: said venting flow path is bounded in part by a generally straight terminus of said reed spring, the muffler further comprising: a cup-shaped spark arrestor seated in said generally circular exhaust outlet and extending into said housing.

Claim 24

The muffler according to claim 13 wherein: said exhaust outlet is generally circular and provides said curved peripheral boundary by a scalloped periphery of said exhaust outlet.

Claim 25

The muffler according to claim 13 wherein said reed has a generally arcuate end, and wherein: said generally curved peripheral boundary is defined in part by said arcuate end of said reed.

Claim 26

The muffler according to claim 13 in combination with said internal combustion engine and a chain saw assembly on which said muffler and said engine are mounted, and wherein: said chain saw assembly includes a generally planar guide bar extending longitudinally at one end thereof; said exhaust outlet of said muffler being generally circular and oriented in a direction generally normal to the plane of said guide bar; said venting flow path being in part defined by said generally circular exhaust outlet and a generally straight terminus of said reed spring inclined with respect to the longitudinal extent of said reed spring.