CA1145678A - Two stroke cycle engine tuned reactor muffler exhaust system - Google Patents
Two stroke cycle engine tuned reactor muffler exhaust systemInfo
- Publication number
- CA1145678A CA1145678A CA000336272A CA336272A CA1145678A CA 1145678 A CA1145678 A CA 1145678A CA 000336272 A CA000336272 A CA 000336272A CA 336272 A CA336272 A CA 336272A CA 1145678 A CA1145678 A CA 1145678A
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- Prior art keywords
- exhaust
- conduit
- exhaust port
- set forth
- combustion chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Exhaust Silencers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed herein is an internal combustion engine including a combustion chamber having an exhaust port which is periodically opened and closed, the exhaust port emitting exhaust containing a pressure wave when the exhaust port is opened, and a noise attenuating muffler connected to the exhaust port. The muffler includes an exhaust conduit in communication with the exhaust port, the exhaust conduit being constructed to facilitate heating of the exhaust in the exhaust conduit and combustion of unburned hydrocarbons and carbon monoxide in the exhaust emitted from the exhaust port. The exhaust conduit is also constructed to cause the pressure wave traveling in the exhaust conduit to return toward the exhaust port, as a pressure wave, and to afford arrival of the pressure wave at the exhaust port prior to the closing of the exhaust port.
Disclosed herein is an internal combustion engine including a combustion chamber having an exhaust port which is periodically opened and closed, the exhaust port emitting exhaust containing a pressure wave when the exhaust port is opened, and a noise attenuating muffler connected to the exhaust port. The muffler includes an exhaust conduit in communication with the exhaust port, the exhaust conduit being constructed to facilitate heating of the exhaust in the exhaust conduit and combustion of unburned hydrocarbons and carbon monoxide in the exhaust emitted from the exhaust port. The exhaust conduit is also constructed to cause the pressure wave traveling in the exhaust conduit to return toward the exhaust port, as a pressure wave, and to afford arrival of the pressure wave at the exhaust port prior to the closing of the exhaust port.
Description
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TITLE: TWO STKOKE CYCLE ENGINE T~NED REACTOR
MUFFLER EXHAUST SYSTEM
INVENTOR: JAMES A. DONOHUE
ACKGROUND OF THE INVENTION
The invention relates generally to internal com-bustion engines and to exhaust gas discharge arrange-ments therefore, and more particularly to tuned exhaust systems also providing thermal reactors to reduce emitted exhaust pollutants.
In the past, various arrangements have been uti-lized to employ returning positive acoustical pressure waves emitted by an exhaust port to exert an influence on the condition of the charge in the combustion chamber and to thereby affect the horsepower output of the en~ine. Examples of such arrangements are disclosed in the Eollowing U.S. patents:
Kadenacy 2,102,559 issued December 14, 1937 Holtermann 3,385,052 issued May 28, 1968 Miller 3,520,270 issuecl JuLy 14, 1970 2n E~oerma 3,543,509 issuecl December 1, 1970 Mlller et al 3,692,006 issued September 19, 1972 Boerma 3,695,238 issued October 13, 1972 Various arran~ements have also been utilized in prior art apparatus to cause further combustion of ` 25 engine exhaust to prevent dischar~e of pollutants.
Such devices are intended to cause unburned hydrocarbons in the exhaust to be oxydized to form water vapor and carbon dioxide and to cause carbon monoxide in the exhaust to form carbon dioxide. Examples of such prior . -2->~
arrangements are disclosed in the following U. S. patents:
~IcCrocklin 3,601,982 issued August 31, 1971 Betz 3,817,716 issued June 18, 1974 Volker 3,690,840 issued September 12, 1978 Grantham 3,817,715 issued June 18, 1974 Hanaoka 3,972,685 issued August 3, 1976 SU~ARY OF THE II~E~ITION
The invention provides an internal combustion engine including a combustion chamber having an ~l~St~
exhaust port which is periodically opened and closed, which exhaust port emits exhaust containing a pressure wave when the exhaust port is opened, and a noise attenuating muffler connected to the exhaust port, which `;
muffler includes an exhaust conduit in communication with the exhaust port, which exhaust conduit includes means for returning toward the exhaust port, as a pressure wave, the pressure wave traveling in the exhaust conduit, and means for effecting combustion in the exhaust conduit of unburned hydrocarbons and carbon monoxide in exhaust emitted from the exhaust port, which means for effecting combustion includes a core portion connected to the exhaust port and providing for exhaust flow in a first direction, an intermediate conduit portion concentrically surrounding the core portion and providing for exhaust flow in a direction opposite the first direction, and an outer conduit portion concentrically surrounding the intermediate conduit portion and providing for exhaust flow from the intermediate conduit portion in the first direction, at least a portion of the exhaust conduit substantially continuously increasing in internal cross sectional area in the direction away from the port and terminating in a wall transverse to the direction, which exhaust conduit also includes an opening located adjacent to the wall and having a relatively small area as compared to the area of the wall.
Other features and advantages of the invention will become known by reference to the following description, to the appended claims, and to the drawings.
,:
BRIEF D~SCRIPTION OF THE DRAWINGS
Figure l ;s a fragmentary view, partially broken away and in section, o~ an internal combustion engine incorporating an exhaust gas arrangement including various of the features of the invention.
Figure 2 is an enlarged cross-section view taken along line 2-2 in Fig. 1.
Figure 3 is an enlarged cross-section view taken along line 3-3 in Fig. 1 and partially broken away.
Figure 4 is a cross-section view taken along line 4-4 in Fig. 3~
Figure 5 is a view of an exhaust gas arrangement similar to that shown in Figure l and with portions broken away and showing an exhaust gas igniter position-ed adjacent the muffler outlet.
Figure 6 is a view similar to Fig. 5 and showingan iKniter in the exhaust gas arrangement positioned between the engine and the muffler.
Figure 7 is a view similar to Figs. 5 and 6 and showing a catalytic unit clisposed in the exhaust conduit of the exhaust gas arrangement.
Fip~ure 8 is a perspective view of ~he mixing vane shown in Figure l.
Before explaining the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the follow-ing description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is ;',~
,~
~ 78 to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Shown in a partial view in Fig. 1 is an internal combustion engine 10 which can have any conventional construction and which includes a combustion chamber 12 and an exhaust port 14 in the wall 16 of the combustion chamber 12. The exhaust port 14 is periodically opened and closed during operation of the engine 10 to permit exhaust gas exit therefrom. Extending from the exhaust port 14 is an exhaust gas discharge arrangement 18 including a noise attenuating muffler 20 connected to the exhaust port 14 by an exhaust manifold or pipe 22.
The muffler 20 is intended to provide a noise attenua-tion means and also provides means for effecting heatin~, and combustion of the unburned hydrocarbon and carbon monoxide entrained in the exhaust emitted from the exhaust port 14. The mu~Eler 20 Eurther provides improved eE~iciency and power output Erom the engine 10 by providin~, means Eor returnin~ toward Lhe exhaust port as a pressure wave, the pressure wave traveling in the exhaust gas discharge arrangement and for causing return of the pressure wave toward the exhaust port 14 to afford arrival of the pressure wave at the exhaust port 1~ prior to closing of the exhaust port.
As shown in the construction illustrated in Fig.
1, the noise attenuating muffler includes a thin metal shell outer wall 24 and end walls 26 and 28. The ~ 8 muffler 20 also includes means for preventing heat loss from the muffler. To provide such means the external surface of the outer shell 24 is covered by an insulat-ing layer 25 and the end walls 26 and 28 are covered by insulating layers 27 and 29, respectively. The insulat-ing layers 25, 27, and 29 are each comprised of two thin metal layers 30 and 32 ~andwiching therebetween a layer of heat resistant insulative material 34. The muffler 20 also includes a central cylindrical thermal reaction core or conduit 36 housed concentrically in the outer shell 24 and having one end extending through the end wall 26 and through the insulating layer 27.
The end of the cylindrical reaction core 36 extending through the wall 26 abuts and is co-axial with an end of a central conduit 38 of the exhaust manifold 22 to thereby facilitate flow of the exhaust gases from the exhaust port 14 throuKh the central conduit 38 of the exhaust manifold 22 and into the cylindricaL reaction core 36 of the muffler 20.
Like the muffler 20, the exhaust manifold 22 and the projectin~ end of the reaction core 36 are surround-ed by insulating lsyers 40 and 41, respectively. The in0ulatin~ layer 40 includes two thin metal layers 42 and 43 sandwiching therebetween a heat resistant insu-lating material 44. The insulating layer 41 similarly includes two thin metal layers 45 and 47 sandwiching therebetween a layer of insulating material 49.
The muffler 20 further includes an intermediate diffuser section 46 housed within the outer shell 24 and surrounding the reaction core 36. The diffuser ~ ~ ~ 5 ~
section 46 comprises a hollow truncated conical conduit having a small diameter end, positioned adjacent the ; end wall 28, and a larger diameter end positioned adjacent to but spaced from the end wall 26. The larger diameter end of the diffuser section 46 is supported in concentric relationship with respect to the reaction core 36 and the outer shell 24 by a plurality of spacing members 48 suitably secured to the : large diameter end of diffuser section 46 and to the inner surface of the outer shell 24.
The muffler 20 also includes an exhaust gas outlet pipe 50 extending through an opening 52 in the end wall 28 and through the insulation layer 29. The outlet pipe 50 is intended to provide exit of the exhaust gases from the muffler 20.
As illustrated in Fig. l, the exhaust gases flow-ing from the exhaust port 14 and through the exhaust manifold 22 will flow through the reaction core 36 and then into the surrounding diffuser section 46. The intermediAte diEfuser section 46 will cause the exhaust ~ases to reverse their direction of flow and cause them .; to surround the reaction core 36 and move in a direction oppos:ite the direction of flow in the reaction core 36.
The exhaust gase~ exiting from the large diameter end of the diffuser section 46 into the conduit portion defined between the outer shell 24 and the diffuser section 46 will be caused to again reverse their direction of flow such that they surround the diffuser section 46 and move toward the end wall 28. The ` 30 exhaust gases are permitted to exit through the exhaust gas opening 52 and outlet pipe 50.
.
..
In operation, combustion of fuel in the combustion chamber 12 of the internal combustion engine L0, and consequent opening of the exhaust port 14 results in discharge of exhaust gases into the exhaust manifold 22 and into the exhaust conduit of the muffler 20. Such discharge of the exhaust gases into the exhaust manifold 22 results in one or more positive or compressive pressure waves which will travel through the exhaust conduit at the local speed of sound. The exhaust conduit, defined by the reaction core 36, the diffuser section 46, and the outer shell, is constructed to have a continuously increasing cross-sectional area in the direction of exhaust flow, the exhaust conduit thereby providing for continuous propagation of the compressive pressure waves until the pressure waves reach the end wall 28. Slnce the end wall 28 is transverse to the direction of exhaust flow and since the cross-sectional area opening 52 i8 relatively .small when compared to the crosæ-æectional area of the exhausL conduit adjacent the end walL 28, the positive pressure waves propagated through the exhaust conduiL will impinge upon the end wall 28 and will rebound towflrcl the exhaust port 14.
The exhaust conduit defined within the muf~ler 20 is also dimensioned such that the returning pressure waves ; 25 are intended to arrive at the exhaust port 14 prior to closing of the exhaust port.
Exhaust emitted from internal combustion engines such as the engine 10 commonly includes unburned hydrocarbons and carbon monoxide, these components being primary constituents of common air pollution. If ~ ~ ~ 5~7 ~
the exhaust gas emitted from the exhausL port 14 can be heated sufficiently, the elevated temperature of the exhaust gases will facilitate further combustion or oxidation of the constituents of the exhaust gases such that the hydrocarbons therein ~ill be converted to carbon dioxide and water vapor, and the carbon monoxide contained in the exhaust can be converted to carbon dioxide.
As previously stated, the construction of the muffler 20 also provides means for causing such heating of the exhaust gases emitted from the exhaust port 14, to thereby facilitate combustion or oxidation of the unburned hydrocarbons and carbon monoxide contained in the exhaust reducing the pollutants emitted by the engine 10. Gases passing through the reaction core 36 .` from the conduit 38 of the exhaust manifold 22 are caused to recirculate between the reaction core 36 and the intermediate diffuser section 46 whereby the exhaust ~ases surrounding the reaction core 36 provide for elevated temperatures therein. The exhaust gases passing between ~he reaction core 36 and the diffuser section 46 are maintained in an elevated temperature because the exhaust ~,as leavin~ the diffuser section 46 .. is caused to ~low in a reverse direction over the exterior surface of the diffuser section 46 as the exhaust gases move toward the end wall 28 and the `: outlet pipe 50. Accordingly, the exhaust gases in the reaction core 36 and those between the core and the . diffuser section 46 are maintained at elevated tempera-30 tures thereby facilitating oxidation of unburned ., ' .:
hydrocarbons and carbon monoxide contained ;n the exhaust.
Means are further provided for forcing air into the exhaust ~ases emitted by the exhaust port 14 to further improve the combustion or oxidation of the exhaust gases within the muffler 20. By adding air to the exhaust gases, additional oxygen is made available in the reaction core 36 and in the diffuser section 46 to facilitate conversion of the carbon monoxide to carbon dioxide and to permit oxidation of the hydro-carbons. The means for adding air to ehe exhaust gases includes an air inlet conduit 54 projecting through the central conduit 38 of the manifold 22 and connected to a suitable air pump 56. While the air could be injected into the exhaust conduit at various locations along the length of the exhaust conduit, in the illustrated construction, the air inlet conduit 54 injects air into the exhauæt manifold 22 intermediate the exhaust port 14 and the projectinR end of the reactor core 36. In a preEerred form oE the invention, the means Eor injecting air into the exhaust gases in;jects air tan~entially into Lhe exhaust manifold 22 to cause swirling of the air therein. Accordingly, the air inlet conduit 5~
includes an inwardly extending end 58 which i9 position-ed within the central conduit 38 adjacent the side wallof the conduit to cause airflow around the periphery conduit and in the direction of exhaust flow. By ~ causing tangential or peripheral swirling movement of : the air injected into the exhaust manifold 22, reverse ~ 30 airflow into the combustion chamber 12 is minimized j:
: -12-and mixing of the air and exhaust gases is facilitated.
Means are also provided to cause pulsing of the air through the airduct 54 and into the exhaust manifold 22 durin~ each cycle of the opening of the exhaust port 14. If air is forced into the exhaust manifold when the exhaust port 14 is closed, that air does not mix with the exhaust gas and merely functions to cause cooling of the exhaust manifold 22 and the muffler 20 thereby decreasing the rate of combustion of the exhaust gases therein. In the illustrated construction, the means for controlling flow of air through the condu;t 54 and for injecting air into the exhaust manifold 22 when the exhaust port 14 is opened, includes a rotary valve 60 connected to the conduit 54. The rotary valve 60 includes a valve body 64 supported by the engine lO and having therein a cylindrical bore 66.
The air conduit 62 communicates with the bore 66 through a port 68, and a conduit 54 similarly communi-cates with bore 66 through a port 70. The valve 60 20 also includes a cylindrical valve rotor 72 housed within the bore 66 and rotatably supported aL its opposite ends by mounting brackets 74 and 76, the mounting brackets 74 and 76 being supported by the engine 10. The valve rotor 72 iR rotatably driven by a pulley 78 fixedly attached to one of the ends of the valve rotor 72. The pulley 78 is driven by a belt 80, the belt 80 being suitably driven by the engine crank-shaft (not shown). The valve rotor 72 also includes a flat 84 providing a passage between the ports 68 and 70. In operation, as the rotor 72 is caused to rotate, ~ 7~
periodic communication between the ports 68 and 70 is provided.
Means can also be provided for causing mixing of the air injected into the exhaust gases to further facilitate combustion of the exhaust gas elements.
While various arrangements can be provided, in the illustrated construction, the means for causing mixing includes a mixing vane 90 disposed in the reactor core 36. The mixing vane 90 is comprised of a thin elongated metal strip bent to form an undulating bowtie configura-tion as illustrated in Figs. 1 and 8 and functional to cause nonlinear airflow paths through the reactor core 36 and consequent mixing of air and exhaust gases.
When the engine 10 is operated at low speeds or when the engine is only lightly loaded, the exhaust gases emitted through the exhaust port 14 may not reach sufficiently high temperatures in the reaction chamber defined by the muffler 20 to facilitate oxidation of the exhaust gases. Accordingly, means can be further ; 20 provicled for causing ignition of the exhaust gases contained in the exhaus- conduit and for maintaining combustion o the exhaust gases when the engine is operated at such low speecls or at lower loads.
While various arrangements can be proviclecl, in the construction illustrated in Figs. 1 and 4, the means for causing ignition includes an igniter 92 including a generally circular body 94 including a cylindrical portion 96 projecting through insulation layer 29 and the end wall 28 and having an inwardly facing circular surface 98. The igniter body 94 :
:',.
`~ -14-'''' also includes an annular portion 100 suitably secured against the insulation layer 29 adjacent the end wall 28. The cylindrical portion 96 of the igniter body includes an annular groove 102 ~herein, the groove opening into the exhaust conduit of the muffler 20.
The inwardly facing circular surface 98 of the cylin-drical portion 96 and the annular groove 102 are covered by a perforated face plate 104. The annular groove 102 and the perforated plate 104 define a combustion chamber therebetween. The perforation 106 in the perforated face plate providing fluid communica-tion between the combustion chamber and the exhaust conduit. The perforated face plate 104 is secured against the circular surface 98 of the cylindrical portion 96 by a screw 107.
Means are further provided for supplying a combus-t:ib].e fuel mixture to the annular groove 102. While various arrangements can be provided, in the illustrated construction a fuel mixture such as that contained in the engine crankcase or intake manifold is conveyed through a suitable conduiL l.08 and through a narrow bore 110 in the body o~ the igniLer to the annular ~roove 102. The conduit L08 is connectecl in f].uid communication with the narrow bore by means of a coupling 112 threadably received in a tapered threaded bore 114 in the body 96. As illustrated in Figure 3, ~ the narrow bore 110 intersects tangentially with the .~ annular groove 102 to provide for swirling flow of the combustible mixture in the annular groove 102.
`':
Means are also provided for igniting the fuel mix-ture in the annular groove 102. As illustrated in Figs. 1, 3 and 4, such means can conveniently comprise a spark plug 116 threadably housed in a threaded bore 11~ in the cylindrical body 9~ and having its electrode 120 extending into the annular groove 102.
As illustrated in Figure 5, in an alternative embodiment, the igniter 92 can be positioned adjacent the end wall 28 but in communication with the portion of the exhaust conduit adjacent the opening 52 and the outlet pipe 50. In that embodiment, the cylindrical body 96 of the igniter is housed in an opening 122 in the outer wall 24 adjacent end wall 28.
Another alternative embodiment is illustrated in Fig. 6, wherein the igniter 92 is shown housed within an opening 124 extending through the wall 38 of the exhaust manifold 22. The igniter 92 shown therein is functional to cause ignition of the exhaus~ gases entecing the reactor core 36.
Another alternative embodiment of the ;nvention is illustrflted in Fi~ure 7 wherein a caLalytic unit 130 is disposed in the exhauæt maniEold 22 and is intended to initiate oxydation of hydrocarbons ancl carbon monoxide. The catalytic unit is particularly effective to initiate oxydation oE exhaust when the engine is operated at low speeds and low loads or during initial operation of the engine. The catalytic unit may include a conventional catalytically active material such as platinum or palladium applied to the surface of a highly porous or honeycomb configuration disposed in ~.~
7~
the exhaust passageway. The catalytic unit 130 may be used in combination with an igniter 92.
Various of the features of the invention are set forth in the ~ollowing claims.
,, .
'`'' ., ,., ,, . ~
~`
TITLE: TWO STKOKE CYCLE ENGINE T~NED REACTOR
MUFFLER EXHAUST SYSTEM
INVENTOR: JAMES A. DONOHUE
ACKGROUND OF THE INVENTION
The invention relates generally to internal com-bustion engines and to exhaust gas discharge arrange-ments therefore, and more particularly to tuned exhaust systems also providing thermal reactors to reduce emitted exhaust pollutants.
In the past, various arrangements have been uti-lized to employ returning positive acoustical pressure waves emitted by an exhaust port to exert an influence on the condition of the charge in the combustion chamber and to thereby affect the horsepower output of the en~ine. Examples of such arrangements are disclosed in the Eollowing U.S. patents:
Kadenacy 2,102,559 issued December 14, 1937 Holtermann 3,385,052 issued May 28, 1968 Miller 3,520,270 issuecl JuLy 14, 1970 2n E~oerma 3,543,509 issuecl December 1, 1970 Mlller et al 3,692,006 issued September 19, 1972 Boerma 3,695,238 issued October 13, 1972 Various arran~ements have also been utilized in prior art apparatus to cause further combustion of ` 25 engine exhaust to prevent dischar~e of pollutants.
Such devices are intended to cause unburned hydrocarbons in the exhaust to be oxydized to form water vapor and carbon dioxide and to cause carbon monoxide in the exhaust to form carbon dioxide. Examples of such prior . -2->~
arrangements are disclosed in the following U. S. patents:
~IcCrocklin 3,601,982 issued August 31, 1971 Betz 3,817,716 issued June 18, 1974 Volker 3,690,840 issued September 12, 1978 Grantham 3,817,715 issued June 18, 1974 Hanaoka 3,972,685 issued August 3, 1976 SU~ARY OF THE II~E~ITION
The invention provides an internal combustion engine including a combustion chamber having an ~l~St~
exhaust port which is periodically opened and closed, which exhaust port emits exhaust containing a pressure wave when the exhaust port is opened, and a noise attenuating muffler connected to the exhaust port, which `;
muffler includes an exhaust conduit in communication with the exhaust port, which exhaust conduit includes means for returning toward the exhaust port, as a pressure wave, the pressure wave traveling in the exhaust conduit, and means for effecting combustion in the exhaust conduit of unburned hydrocarbons and carbon monoxide in exhaust emitted from the exhaust port, which means for effecting combustion includes a core portion connected to the exhaust port and providing for exhaust flow in a first direction, an intermediate conduit portion concentrically surrounding the core portion and providing for exhaust flow in a direction opposite the first direction, and an outer conduit portion concentrically surrounding the intermediate conduit portion and providing for exhaust flow from the intermediate conduit portion in the first direction, at least a portion of the exhaust conduit substantially continuously increasing in internal cross sectional area in the direction away from the port and terminating in a wall transverse to the direction, which exhaust conduit also includes an opening located adjacent to the wall and having a relatively small area as compared to the area of the wall.
Other features and advantages of the invention will become known by reference to the following description, to the appended claims, and to the drawings.
,:
BRIEF D~SCRIPTION OF THE DRAWINGS
Figure l ;s a fragmentary view, partially broken away and in section, o~ an internal combustion engine incorporating an exhaust gas arrangement including various of the features of the invention.
Figure 2 is an enlarged cross-section view taken along line 2-2 in Fig. 1.
Figure 3 is an enlarged cross-section view taken along line 3-3 in Fig. 1 and partially broken away.
Figure 4 is a cross-section view taken along line 4-4 in Fig. 3~
Figure 5 is a view of an exhaust gas arrangement similar to that shown in Figure l and with portions broken away and showing an exhaust gas igniter position-ed adjacent the muffler outlet.
Figure 6 is a view similar to Fig. 5 and showingan iKniter in the exhaust gas arrangement positioned between the engine and the muffler.
Figure 7 is a view similar to Figs. 5 and 6 and showing a catalytic unit clisposed in the exhaust conduit of the exhaust gas arrangement.
Fip~ure 8 is a perspective view of ~he mixing vane shown in Figure l.
Before explaining the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the follow-ing description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is ;',~
,~
~ 78 to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Shown in a partial view in Fig. 1 is an internal combustion engine 10 which can have any conventional construction and which includes a combustion chamber 12 and an exhaust port 14 in the wall 16 of the combustion chamber 12. The exhaust port 14 is periodically opened and closed during operation of the engine 10 to permit exhaust gas exit therefrom. Extending from the exhaust port 14 is an exhaust gas discharge arrangement 18 including a noise attenuating muffler 20 connected to the exhaust port 14 by an exhaust manifold or pipe 22.
The muffler 20 is intended to provide a noise attenua-tion means and also provides means for effecting heatin~, and combustion of the unburned hydrocarbon and carbon monoxide entrained in the exhaust emitted from the exhaust port 14. The mu~Eler 20 Eurther provides improved eE~iciency and power output Erom the engine 10 by providin~, means Eor returnin~ toward Lhe exhaust port as a pressure wave, the pressure wave traveling in the exhaust gas discharge arrangement and for causing return of the pressure wave toward the exhaust port 14 to afford arrival of the pressure wave at the exhaust port 1~ prior to closing of the exhaust port.
As shown in the construction illustrated in Fig.
1, the noise attenuating muffler includes a thin metal shell outer wall 24 and end walls 26 and 28. The ~ 8 muffler 20 also includes means for preventing heat loss from the muffler. To provide such means the external surface of the outer shell 24 is covered by an insulat-ing layer 25 and the end walls 26 and 28 are covered by insulating layers 27 and 29, respectively. The insulat-ing layers 25, 27, and 29 are each comprised of two thin metal layers 30 and 32 ~andwiching therebetween a layer of heat resistant insulative material 34. The muffler 20 also includes a central cylindrical thermal reaction core or conduit 36 housed concentrically in the outer shell 24 and having one end extending through the end wall 26 and through the insulating layer 27.
The end of the cylindrical reaction core 36 extending through the wall 26 abuts and is co-axial with an end of a central conduit 38 of the exhaust manifold 22 to thereby facilitate flow of the exhaust gases from the exhaust port 14 throuKh the central conduit 38 of the exhaust manifold 22 and into the cylindricaL reaction core 36 of the muffler 20.
Like the muffler 20, the exhaust manifold 22 and the projectin~ end of the reaction core 36 are surround-ed by insulating lsyers 40 and 41, respectively. The in0ulatin~ layer 40 includes two thin metal layers 42 and 43 sandwiching therebetween a heat resistant insu-lating material 44. The insulating layer 41 similarly includes two thin metal layers 45 and 47 sandwiching therebetween a layer of insulating material 49.
The muffler 20 further includes an intermediate diffuser section 46 housed within the outer shell 24 and surrounding the reaction core 36. The diffuser ~ ~ ~ 5 ~
section 46 comprises a hollow truncated conical conduit having a small diameter end, positioned adjacent the ; end wall 28, and a larger diameter end positioned adjacent to but spaced from the end wall 26. The larger diameter end of the diffuser section 46 is supported in concentric relationship with respect to the reaction core 36 and the outer shell 24 by a plurality of spacing members 48 suitably secured to the : large diameter end of diffuser section 46 and to the inner surface of the outer shell 24.
The muffler 20 also includes an exhaust gas outlet pipe 50 extending through an opening 52 in the end wall 28 and through the insulation layer 29. The outlet pipe 50 is intended to provide exit of the exhaust gases from the muffler 20.
As illustrated in Fig. l, the exhaust gases flow-ing from the exhaust port 14 and through the exhaust manifold 22 will flow through the reaction core 36 and then into the surrounding diffuser section 46. The intermediAte diEfuser section 46 will cause the exhaust ~ases to reverse their direction of flow and cause them .; to surround the reaction core 36 and move in a direction oppos:ite the direction of flow in the reaction core 36.
The exhaust gase~ exiting from the large diameter end of the diffuser section 46 into the conduit portion defined between the outer shell 24 and the diffuser section 46 will be caused to again reverse their direction of flow such that they surround the diffuser section 46 and move toward the end wall 28. The ` 30 exhaust gases are permitted to exit through the exhaust gas opening 52 and outlet pipe 50.
.
..
In operation, combustion of fuel in the combustion chamber 12 of the internal combustion engine L0, and consequent opening of the exhaust port 14 results in discharge of exhaust gases into the exhaust manifold 22 and into the exhaust conduit of the muffler 20. Such discharge of the exhaust gases into the exhaust manifold 22 results in one or more positive or compressive pressure waves which will travel through the exhaust conduit at the local speed of sound. The exhaust conduit, defined by the reaction core 36, the diffuser section 46, and the outer shell, is constructed to have a continuously increasing cross-sectional area in the direction of exhaust flow, the exhaust conduit thereby providing for continuous propagation of the compressive pressure waves until the pressure waves reach the end wall 28. Slnce the end wall 28 is transverse to the direction of exhaust flow and since the cross-sectional area opening 52 i8 relatively .small when compared to the crosæ-æectional area of the exhausL conduit adjacent the end walL 28, the positive pressure waves propagated through the exhaust conduiL will impinge upon the end wall 28 and will rebound towflrcl the exhaust port 14.
The exhaust conduit defined within the muf~ler 20 is also dimensioned such that the returning pressure waves ; 25 are intended to arrive at the exhaust port 14 prior to closing of the exhaust port.
Exhaust emitted from internal combustion engines such as the engine 10 commonly includes unburned hydrocarbons and carbon monoxide, these components being primary constituents of common air pollution. If ~ ~ ~ 5~7 ~
the exhaust gas emitted from the exhausL port 14 can be heated sufficiently, the elevated temperature of the exhaust gases will facilitate further combustion or oxidation of the constituents of the exhaust gases such that the hydrocarbons therein ~ill be converted to carbon dioxide and water vapor, and the carbon monoxide contained in the exhaust can be converted to carbon dioxide.
As previously stated, the construction of the muffler 20 also provides means for causing such heating of the exhaust gases emitted from the exhaust port 14, to thereby facilitate combustion or oxidation of the unburned hydrocarbons and carbon monoxide contained in the exhaust reducing the pollutants emitted by the engine 10. Gases passing through the reaction core 36 .` from the conduit 38 of the exhaust manifold 22 are caused to recirculate between the reaction core 36 and the intermediate diffuser section 46 whereby the exhaust ~ases surrounding the reaction core 36 provide for elevated temperatures therein. The exhaust gases passing between ~he reaction core 36 and the diffuser section 46 are maintained in an elevated temperature because the exhaust ~,as leavin~ the diffuser section 46 .. is caused to ~low in a reverse direction over the exterior surface of the diffuser section 46 as the exhaust gases move toward the end wall 28 and the `: outlet pipe 50. Accordingly, the exhaust gases in the reaction core 36 and those between the core and the . diffuser section 46 are maintained at elevated tempera-30 tures thereby facilitating oxidation of unburned ., ' .:
hydrocarbons and carbon monoxide contained ;n the exhaust.
Means are further provided for forcing air into the exhaust ~ases emitted by the exhaust port 14 to further improve the combustion or oxidation of the exhaust gases within the muffler 20. By adding air to the exhaust gases, additional oxygen is made available in the reaction core 36 and in the diffuser section 46 to facilitate conversion of the carbon monoxide to carbon dioxide and to permit oxidation of the hydro-carbons. The means for adding air to ehe exhaust gases includes an air inlet conduit 54 projecting through the central conduit 38 of the manifold 22 and connected to a suitable air pump 56. While the air could be injected into the exhaust conduit at various locations along the length of the exhaust conduit, in the illustrated construction, the air inlet conduit 54 injects air into the exhauæt manifold 22 intermediate the exhaust port 14 and the projectinR end of the reactor core 36. In a preEerred form oE the invention, the means Eor injecting air into the exhaust gases in;jects air tan~entially into Lhe exhaust manifold 22 to cause swirling of the air therein. Accordingly, the air inlet conduit 5~
includes an inwardly extending end 58 which i9 position-ed within the central conduit 38 adjacent the side wallof the conduit to cause airflow around the periphery conduit and in the direction of exhaust flow. By ~ causing tangential or peripheral swirling movement of : the air injected into the exhaust manifold 22, reverse ~ 30 airflow into the combustion chamber 12 is minimized j:
: -12-and mixing of the air and exhaust gases is facilitated.
Means are also provided to cause pulsing of the air through the airduct 54 and into the exhaust manifold 22 durin~ each cycle of the opening of the exhaust port 14. If air is forced into the exhaust manifold when the exhaust port 14 is closed, that air does not mix with the exhaust gas and merely functions to cause cooling of the exhaust manifold 22 and the muffler 20 thereby decreasing the rate of combustion of the exhaust gases therein. In the illustrated construction, the means for controlling flow of air through the condu;t 54 and for injecting air into the exhaust manifold 22 when the exhaust port 14 is opened, includes a rotary valve 60 connected to the conduit 54. The rotary valve 60 includes a valve body 64 supported by the engine lO and having therein a cylindrical bore 66.
The air conduit 62 communicates with the bore 66 through a port 68, and a conduit 54 similarly communi-cates with bore 66 through a port 70. The valve 60 20 also includes a cylindrical valve rotor 72 housed within the bore 66 and rotatably supported aL its opposite ends by mounting brackets 74 and 76, the mounting brackets 74 and 76 being supported by the engine 10. The valve rotor 72 iR rotatably driven by a pulley 78 fixedly attached to one of the ends of the valve rotor 72. The pulley 78 is driven by a belt 80, the belt 80 being suitably driven by the engine crank-shaft (not shown). The valve rotor 72 also includes a flat 84 providing a passage between the ports 68 and 70. In operation, as the rotor 72 is caused to rotate, ~ 7~
periodic communication between the ports 68 and 70 is provided.
Means can also be provided for causing mixing of the air injected into the exhaust gases to further facilitate combustion of the exhaust gas elements.
While various arrangements can be provided, in the illustrated construction, the means for causing mixing includes a mixing vane 90 disposed in the reactor core 36. The mixing vane 90 is comprised of a thin elongated metal strip bent to form an undulating bowtie configura-tion as illustrated in Figs. 1 and 8 and functional to cause nonlinear airflow paths through the reactor core 36 and consequent mixing of air and exhaust gases.
When the engine 10 is operated at low speeds or when the engine is only lightly loaded, the exhaust gases emitted through the exhaust port 14 may not reach sufficiently high temperatures in the reaction chamber defined by the muffler 20 to facilitate oxidation of the exhaust gases. Accordingly, means can be further ; 20 provicled for causing ignition of the exhaust gases contained in the exhaus- conduit and for maintaining combustion o the exhaust gases when the engine is operated at such low speecls or at lower loads.
While various arrangements can be proviclecl, in the construction illustrated in Figs. 1 and 4, the means for causing ignition includes an igniter 92 including a generally circular body 94 including a cylindrical portion 96 projecting through insulation layer 29 and the end wall 28 and having an inwardly facing circular surface 98. The igniter body 94 :
:',.
`~ -14-'''' also includes an annular portion 100 suitably secured against the insulation layer 29 adjacent the end wall 28. The cylindrical portion 96 of the igniter body includes an annular groove 102 ~herein, the groove opening into the exhaust conduit of the muffler 20.
The inwardly facing circular surface 98 of the cylin-drical portion 96 and the annular groove 102 are covered by a perforated face plate 104. The annular groove 102 and the perforated plate 104 define a combustion chamber therebetween. The perforation 106 in the perforated face plate providing fluid communica-tion between the combustion chamber and the exhaust conduit. The perforated face plate 104 is secured against the circular surface 98 of the cylindrical portion 96 by a screw 107.
Means are further provided for supplying a combus-t:ib].e fuel mixture to the annular groove 102. While various arrangements can be provided, in the illustrated construction a fuel mixture such as that contained in the engine crankcase or intake manifold is conveyed through a suitable conduiL l.08 and through a narrow bore 110 in the body o~ the igniLer to the annular ~roove 102. The conduit L08 is connectecl in f].uid communication with the narrow bore by means of a coupling 112 threadably received in a tapered threaded bore 114 in the body 96. As illustrated in Figure 3, ~ the narrow bore 110 intersects tangentially with the .~ annular groove 102 to provide for swirling flow of the combustible mixture in the annular groove 102.
`':
Means are also provided for igniting the fuel mix-ture in the annular groove 102. As illustrated in Figs. 1, 3 and 4, such means can conveniently comprise a spark plug 116 threadably housed in a threaded bore 11~ in the cylindrical body 9~ and having its electrode 120 extending into the annular groove 102.
As illustrated in Figure 5, in an alternative embodiment, the igniter 92 can be positioned adjacent the end wall 28 but in communication with the portion of the exhaust conduit adjacent the opening 52 and the outlet pipe 50. In that embodiment, the cylindrical body 96 of the igniter is housed in an opening 122 in the outer wall 24 adjacent end wall 28.
Another alternative embodiment is illustrated in Fig. 6, wherein the igniter 92 is shown housed within an opening 124 extending through the wall 38 of the exhaust manifold 22. The igniter 92 shown therein is functional to cause ignition of the exhaus~ gases entecing the reactor core 36.
Another alternative embodiment of the ;nvention is illustrflted in Fi~ure 7 wherein a caLalytic unit 130 is disposed in the exhauæt maniEold 22 and is intended to initiate oxydation of hydrocarbons ancl carbon monoxide. The catalytic unit is particularly effective to initiate oxydation oE exhaust when the engine is operated at low speeds and low loads or during initial operation of the engine. The catalytic unit may include a conventional catalytically active material such as platinum or palladium applied to the surface of a highly porous or honeycomb configuration disposed in ~.~
7~
the exhaust passageway. The catalytic unit 130 may be used in combination with an igniter 92.
Various of the features of the invention are set forth in the ~ollowing claims.
,, .
'`'' ., ,., ,, . ~
~`
Claims (14)
1. An internal combustion engine including a combus-tion chamber having an exhaust port which is periodically opened and closed, said exhaust port emitting exhaust containing a pressure wave when said exhaust port is opened, and a noise attenuating muffler connected to said exhaust port, said muffler including an exhaust conduit in communica-tion with said exhaust port, said exhaust conduit including means for returning toward said exhaust port, as a pressure wave, the pressure wave traveling in said exhaust conduit, and means for effecting combustion in said exhaust conduit of unburned hydrocarbons and carbon monoxide in exhaust emitted from said exhaust port, said means for effecting combustion including a core portion connected to said exhaust port and providing for exhaust flow in a first direction, an intermediate conduit portion concentrically surrounding said core portion and providing for exhaust flow in a direction opposite said first direction, and an outer conduit portion concentrically surrounding said intermediate conduit portion and providing for exhaust flow from said intermediate conduit portion in said first direction, at least a portion of said exhaust conduit substantially continuously increasing in internal cross sectional area in the direction away from said port and terminating in a wall transverse to said direction, said exhaust conduit also including an opening located adjacent to said wall and having a relatively small area as compared to the area of said wall.
2 An internal combustion engine as set forth in Claim 1 wherein said intermediate conduit portion includes opposite ends, one of said ends being located adjacent but spaced from said opening, said intermediate conduit portion increasing in diameter from said one of said opposite ends toward the other of said opposite ends.
3. An internal combustion engine as set forth in Claim 1 wherein said means for effecting combustion includes means for igniting said exhaust gas in said exhaust conduit.
4. An internal combustion engine as set forth in Claim 3 wherein said means for igniting includes a catalytic unit disposed in said exhaust conduit, said catalytic unit including a catalytically active material for causing combustion of exhaust gases.
5. An internal combustion engine as set forth in Claim 3 wherein said means for igniting includes a housing having a combustion chamber therein, said combustion chamber communicating with said exhaust conduit, means for supplying fuel to said combustion chamber, and means for generating a flame in said combustion chamber.
6. Apparatus as set forth in Claim 5 wherein said combustion chamber is located adjacent said exhaust port.
7. Apparatus as set forth in Claim 1 wherein said means for effecting combustion includes means for introducing air into said exhaust conduit to mix air with exhaust in said exhaust conduit.
8. An internal combustion engine as set forth in Claim 7 wherein said means for introducing air into said exhaust conduit includes an airflow supply means and valve means between said airflow supply means and said exhaust conduit and for causing cylical injection of air into said exhaust conduit.
9. An internal combustion engine as set forth in Claim 7 wherein said means for effecting combustion includes means for igniting the intermixed air and exhaust gases.
10. An internal combustion engine as set forth in Claim g wherein said means for igniting includes a catalytic unit disposed in said exhaust conduit, said catalytic unit including a catalytically active material for causing combustion of exhaust gases.
11. An internal combustion engine as set forth in Claim 9 wherein said means for igniting includes a housing having a combustion chamber therein, said combustion chamber communicating with said exhaust conduit, means for supplying fuel to said combustion chamber, and means for generating a flame in said combustion chamber.
12. An internal combustion engine as set forth in Claim 11 wherein said combustion chamber is located adjacent said exhaust port.
13. An internal combustion engine as set forth in Claim 11 wherein said combustion chamber is located adjacent said opening and communicates with said intermediate conduit portion.
14. An internal combustion engine as set forth in Claim 11 wherein said combustion chamber is located adjacent said opening and communicates directly with said outer conduit portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US95228178A | 1978-10-18 | 1978-10-18 | |
| US952,281 | 1978-10-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1145678A true CA1145678A (en) | 1983-05-03 |
Family
ID=25492739
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000336272A Expired CA1145678A (en) | 1978-10-18 | 1979-09-25 | Two stroke cycle engine tuned reactor muffler exhaust system |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5557612A (en) |
| CA (1) | CA1145678A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1985004689A1 (en) * | 1984-04-09 | 1985-10-24 | Orbital Engine Company Proprietary Limited | Two-stroke engine variable tuned exhaust system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06200754A (en) * | 1992-12-29 | 1994-07-19 | Fujitsubo Giken Kogyo Kk | Exhaust gas harmful component reducing device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4842218A (en) * | 1971-10-02 | 1973-06-20 | ||
| JPS5013888A (en) * | 1973-06-11 | 1975-02-13 |
-
1979
- 1979-09-25 CA CA000336272A patent/CA1145678A/en not_active Expired
- 1979-10-18 JP JP13471479A patent/JPS5557612A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1985004689A1 (en) * | 1984-04-09 | 1985-10-24 | Orbital Engine Company Proprietary Limited | Two-stroke engine variable tuned exhaust system |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5557612A (en) | 1980-04-28 |
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| MKEX | Expiry |