Exhaust method and apparatus for a dual cylinder two-cycle engine

Claim 2

An exhaust system for a dual cylinder two-cycle engine having at least an exhaust port fashioned within each cylinder, said exhaust system comprising: a first tubular member having an increasing cross-sectional area transverse to the central axis of said first tubular member beginning at one end thereof and increasing to the other end thereof, said one end of said first tubular member being directly connectable to the exhaust port in one of said dual cylinders with the central axis of said first tubular member at said one end thereof extending generally normal to the central axis of said one of said dual cylinders, said first tubular member being bent approximately 90.degree. at a location slightly downstream from said one end thereof wherein the central axis of said first tubular member lies approximately parallel with the central axis of said one of said dual cylinders and the first tubular member extends contiguous with but spaced from the exterior surface of said one of said dual cylinders, and said first tubular member again being bent approximately 90.degree. slightly upstream from the other end thereof wherein the central axis thereof is approximately normal to the central axis of said one of said dual cylinders and parallel with the central axis of said first tubular member at said one end thereof whereby the other end of said first tubular member extends contiguous with but spaced from a top exterior surface of said one of said dual cylinders; a second tubular member having an increasing cross-sectional area transverse to the axis of said second tubular member beginning at one end thereof and increasing to the other end thereof, said one end of said second tubular member being directly connectable to the exhaust port in the other of said dual cylinders with the central axis of said second tubular member at said one end thereof extending generally normal to the central axis of said other of said dual cylinders, said second tubular member being bent approximately 90.degree. at a location slightly downstream from said one end thereof wherein the central axis of said second tubular member lies approximately parallel with the central axis of said other of said dual cylinders and the second tubular member extends contiguous with but spaced from the exterior surface of said other of said dual cylinders, and said second tubular member again being bent approximately 90.degree. slightly upstream from the other end thereof wherein the central axis thereof is approximately normal to the central axis of said other of said dual cylinders and parallel with the central axis of said second tubular member at said one end thereof whereby the other end of the second tubular member extends contiguous with but spaced from a top exterior surface of said other of said dual cylinders; a third tubular member having a generally constant cross-sectional area interconnecting the other ends of said first and said second tubular members, said third tubular member having an axial dimension such that during scavenging of said one of said dual cylinders exhaust gases will travel from the exhaust port of said one cylinder through said first tubular member and said third tubular member to said second tubular member compress and reflect as a first positive pressure wave therefrom back to said one cylinder just prior to the exhaust port therein closing to create a positive back pressure at the exhaust port of said one cylinder and such that at least exhaust gases will travel from the exhaust port of said other of said dual cylinders through said second, third and first tubular members, compress and rereflect between said first and second tubular members and arrive as a second positive pressure wave at the exhaust port of said one cylinder to reinforce and increase the average intensity of said first positive pressure wave at the exhaust port of said one cylinder, and said third tubular member further having an axial dimension such that during scavenging of said other of said dual cylinders exhaust gases will travel from the exhaust port of said other cylinder through said second tubular member and said third tubular member to said first tubular member compress and reflect as a third positive pressure wave therefrom back to said other cylinder just prior to the exhaust port therein closing to create a positive back pressure at the exhaust port of said other cylinder and such that at least exhaust gases will travel from the exhaust port of said one cylinder through said first, third and second tubular members compress and rereflect between said first and second tubular members and arrive as a fourth positive pressure wave at the exhaust port of said other cylinder to reinforce and increase the average intensity of said third pressure wave at the exhaust port of said other cylinder; and an exhaust conduit tapped into said third tubular member to permit the escape of exhaust gase from within said third tubular member to the atmosphere.

Claim 3

An exhaust system for a two-cycle engine having first and second cylinders with first and second exhaust ports, respectively, said exhaust system comprising: a first tubular member, the cross-sectional area of which increases from an inner end thereof to an outer end thereof; said inner end of said first tubular member being connectable to said first exhaust port; a second tubular member, the cross-sectional area of which increases from an inner end thereof to an outer end thereof; said inner end of said second tubular member being connectable to said second exhaust port; a third tubular member having a generally cylindrical configuration of generally constant cross-sectional area interconnecting the outer ends of said first and second tubular members; exhaust opening means in said third tubular member to discharge at least some exhaust gases flowing through said third tubular member; said tubular members being arranged to conduct a first flow of exhaust gases from said first exhaust port and to: cause expansion of said first exhaust flow in said first tubular member for reflecting first negative pressure pulses back to said first exhaust port in a manner facilitating the discharge of said first exhaust flow from said first cylinder into said exhaust system, cause convergence of said first exhaust flow in said second tubular member for reflecting first primary positive pressure pulses back to said first exhaust port, prior to the closing thereof, in a manner resisting outward flow from said first exhaust port, and conduct re-reflected first primary pressure pulses from said first tubular member in the form of first secondary positive pressure pulses traveling toward said second exhaust port; said tubular members being arranged to conduct a second flow of exhaust gases from said second exhaust port and to: cause expansion of said second exhaust flow in said second tubular member for reflecting second negative pressure pulses back to said second exhaust port in a manner facilitating the discharge of said second exhaust flow from said second cylinder into said exhaust system, and cause convergence of said second exhaust flow in said first tubular member for reflecting second primary positive pressure pulses back to said second exhaust port, prior to the closing thereof, in a manner resisting outward flow from said second exhaust port, and conduct re-reflected second primary pressure pulses from said second tubular member in the form of second secondary positive pressure pulses traveling toward said first exhaust port; said first, second, and third tubular members having combined axial lengths dimensioned to: conduct said first secondary pressure pulses from said first tubular member toward said second exhaust port in timed sequence to the reflection of said second primary pressure pulses toward said second exhaust port such that said second primary pressure pulses are reinforced by said first secondary pressure pulses, prior to closing of said second exhaust port, to intensify the positive pressure imposed at said second exhaust port, and conduct said second secondary pulses from said second tubular member toward said first exhaust port in timed sequence to the reflection of said first primary pressure pulses toward said first exhaust port such that said first primary pressure pulses are reinforced by said second secondary pressure pulses, prior to closing of said first exhaust port, to intensify the positive pressure imposed at said first exhaust port; the central axis of said first tubular member at said inner end thereof extends generally normal to the central axis of said first cylinder; said first tubular member being bent apoproximately 90.degree. at a location slightly downstream from said inner end thereof wherein the central axis of said first tubular member lies approximately parallel with the central axis of said first cylinder; said first tubular member again being bent approximately 90.degree. slightly upstream from the outer end therof wherein the central axis thereof is approximately normal to the central axis of said first cylinder and parallel with the central axis of said first tubular member at said inner end thereof whereby the outer end of said first tubular member is spaced from a top exterior surface of said first cylinder; the central axis of said second tubular member at said inner end thereof extending generally normal to the central axis of said second cylinder; said second tubular member being bent approximately 90.degree. at a location slightly downstream from said inner end thereof wherein the central axis of said second tubular member lies approximately parallel with the central axis of said second cylinder; and said second tubular member again being bent approximately 90.degree. slightly upstream from the outer end therof wherein the central axis thereof is approximately normal to the central axis of said second cylinder and parallel with the central axis of said second tubular member at said inner end thereof whereby the outer end of the second tubular member is spaced from a top exterior surface of said second cylinder.

Claim 4

An exhaust system for a two-cycle engine having first and second cylinders with first and second exhaust ports, respectively, said exhaust system comprising: a first tubular member, the cross-sectional area of which increases from an inner end thereof to an outer end thereof; said inner end of said first tubular member being connectable to said first exhaust port; a second tubular member, the cross-sectional area of which increases from an inner end thereof to an outer end thereof; said inner end of said second tubular member being connectable to said second exhaust port; a third tubular member having a generally cylindrical configuration of generally constant cross-sectional area interconnecting the outer ends of said first and second tubular members; exhaust opening means in said third tubular member to discharge at least some exhaust gases flowing through said third tubular member; said tubular members being arranged to conduct a first flow of exhaust gases from said first exhaust port and to: cause expansion of said first exhaust flow in said first tubular member for reflecting first negative pressure pulses back to said first exhaust port in a manner facilitating the discharge of said first exhaust flow from said first cylinder into said exhaust system, cause convergence of said first exhaust flow in said second tubular member for reflecting first primary positive pressure pulses back to said first exhaust port, prior to the closing thereof, in a manner resisting outward flow from said first exhaust port, and conduct re-reflected first primary pressure pulses from said first tubular member in the form of first secondary positive pressure pulses traveling toward said second exhaust port; said tubular members being arranged to conduct a second flow of exhaust gases from said second exhaust port and to: cause expansion of said second exhaust flow in said second tubular member for reflecting second negative pressure pulses back to said second exhaust port in a manner facilitating the discharge of said second exhaust flow from said second cylinder into said exhaust system, and cause convergence of said second exhaust flow in said first tubular member for reflecting second primary positive pressure pulses back to said second exhaust port, prior to the closing thereof, in a manner resisting outward flow from said second exhaust port, and conduct re-reflected second primary pressure pulses from said second tubular member in the form of second secondary positive pressure pulses traveling toward said first exhaust port; said first, second, and third tubular members having combined axial lengths dimensioned to: conduct said first secondary pressure pulses from said first tubular member toward said second exhaust port in timed sequence to the reflection of said second primary pressure pulses toward said second exhaust port such that said second primary pressure pulses are reinforced by said first secondary pressure pulses, prior to closing of said second exhaust port, to intensify the positive pressure imposed at said second exhaust port, and conduct said second secondary pulses from said second tubular member toward said first exhaust port in timed sequence to the reflection of said first primary pressure pulses toward said first exhaust port such that said first primary pressure pulses are reinforced by said second secondary pressure pulses, prior to closing of said first exhaust port, to intensify the positive pressure imposed at said first exhaust port; the central axis of said first tubular member at said inner end thereof extends generally normal to the central axis of said first cylinder; said first tubular member being bent apoproximately 90.degree. at a location slightly downstream from said inner end thereof wherein the central axis of said first tubular member lies approximately parallel with the central axis of said first cylinder; said first tubular member again being bent approximately 90.degree. slightly upstream from the outer end therof wherein the central axis thereof is approximately normal to the central axis of said first cylinder and parallel with the central axis of said first tubular member at said inner end thereof whereby the outer end of said first tubular member is spaced from a top exterior surface of said first cylinder; the central axis of said second tubular member at said inner end thereof extending generally normal to the central axis of said second cylinder; said second tubular member being bent approximately 90.degree. at a location slightly downstream from said inner end thereof wherein the central axis of said second tubular member lies approximately parallel with the central axis of said second cylinder; and said second tubular member again being bent approximately 90.degree. slightly upstream from the outer end therof wherein the central axis thereof is approximately normal to the central axis of said second cylinder and parallel with the central axis of said second tubular member at said inner end thereof whereby the outer end of the second tubular member is spaced from a top exterior surface of said second cylinder.