Engine with exhaust manifold converter-reactor
United States Patent 3927525
Arrangements for internal combustion engine exhaust manifold converter-reactors for controlling hydrocarbon, carbon monoxide and nitrogen oxide emissions. The arrangements involve concentric primary and secondary oxidizing zones separated by a tubular element forming a reduction catalyst. A swirl flow is created by tangential entry of inlet ports to the primary oxidizing zones to maximize residence times in the various zones.
US Patent References:
Exhaust manifold reaction system and apparatus
Rosenlund - December 1968 - 3413803
EXHAUST GAS PROCESSING SYSTEM
Brimer - May 1971 - 3577728
EXHAUST MANIFOLD REACTOR
Haddad - January 1972 - 3635031
EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINES
Gotoh - September 1973 - 3756027
INTEGRATED ENGINE EXHAUST EMISSION CONTROL SYSTEM
Tourtellotte - September 1973 - 3757521
Exhaust manifold reaction system and apparatus
Rosenlund - December 1968 - 3413803
EXHAUST GAS PROCESSING SYSTEM
Brimer - May 1971 - 3577728
EXHAUST MANIFOLD REACTOR
Haddad - January 1972 - 3635031
EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINES
Gotoh - September 1973 - 3756027
INTEGRATED ENGINE EXHAUST EMISSION CONTROL SYSTEM
Tourtellotte - September 1973 - 3757521
Application Number:
05/364154
Publication Date:
12/23/1975
Filing Date:
05/25/1973
View Patent Images:
Export Citation:
Assignee:
General Motors Corporation (Detroit, MI)
Primary Class:
Other Classes:
60/323, 60/302, 422/168
International Classes:
F01N3/26; F01N3/28; F01N7/10; F01N3/16
Field of Search:
60/282,301,323,303,302 23/288F
US Patent References:
Other References:
Bentley et al., "Questor Reverter Emission Control System...," SAE Pub. 730227, Jan. 8-12, 1973, pp. 2,3..
Primary Examiner:
Hart, Douglas
Attorney, Agent or Firm:
Outland, Robert J.
Claims:
I claim
1. An exhaust converter-reactor for an internal combustion engine, said converter-reactor comprising
1. An exhaust converter-reactor for an internal combustion engine, said converter-reactor comprising
Description:
BACKGROUND OF THE INVENTION
This invention relates to arrangements of exhaust manifold converter-reactors (C-R's) for internal combustion engines and, more particularly, to C-R manifold arrangements for attachment to and in combination with internal combustion engines.
It is known in the art to provide an internal combustion engine with a converter-reactor (C-R) system for minimizing hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NO x ) in the exhaust gases. Some such systems have involved three operational stages which may take place in separate or combined units, the stages including (1) a primary stage of partial oxidation of HC and CO with added or excess air which heats the gases while maintaining a reducing atmosphere, (2) an intermediate stage of NO x reduction wherein the heated gases from the primary stage are passed through a catalytic element consisting of wire screen or mesh such as copper-clad steel, stainless steel or the like, and (3) a secondary oxidizing stage wherein additional air is added to react with remaining HC and CO in the exhaust gases.
SUMMARY OF THE INVENTION
The present invention provides a family of C-R manifold arrangements for use on and in combination with internal combustion engines and including the common features of concentric primary and secondary oxidizing zones separated by a cylindrical catalytic element for reducing NO x , all combined in a single manifold unit. Means are provided for supplying oxidizing air to both the primary and secondary zones and for insulating the C-R housing against excessive heat loss. The inner and outer sections defined by the catalytic element within the C-R housing may in alternative arrangements comprise either the primary or secondary reaction zones. In either case, exhaust gas inlet ports direct gas tangentially into the primary zone to provide a swirl motion which promotes extended residence time.
These and other features and advantages of the invention will be more fully appreciated and understood by the following description of certain specific arrangements of C-R manifolds formed according to the invention and selected for illustrative purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a side view of a portion of an internal combustion engine having installed thereon a C-R manifold formed according to the invention;
FIG. 2 is a fragmentary end view of the engine of FIG. 1 showing the attached C-R manifold;
FIG. 3 is a cross-sectional view of the engine of FIGS. 1 and 2 taken generally in the plane indicated by the Line 3--3 of FIG. 1; and
FIGS. 4 - 9 are cross-sectional views similar to FIG. 3 but showing various alternative arrangements of engine C-R manifold assemblies.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Referring first to FIGS. 1 - 3 of the drawings, there is shown an internal combustion engine generally indicated by numeral 10. Engine 10 includes the usual cylinder block 12 containing a plurality of cylinders 14 having pistons 16 reciprocably mounted therein. Cylinders 14 are conventionally closed by a cylinder head 18 having inlet valves, not shown, and exhaust valves 20 openable to communicate their respective cylinders 14 with associated exhaust ports 22 formed within the cylinder head 18.
On the side of the cylinder head there are exhaust manifold mounting faces 24 through which the exhaust ports 22 open and to which a C-R manifold generally indicated by numeral 26 is secured by means such as bolts 28 or the like.
Manifold 26 comprises a cast, generally tubular housing 30 extending longitudinally of the engine and enclosing an elongated cylindrical chamber 32. At one end of the housing 30 a downwardly directed outlet passage 34 is formed, connecting with the central portion of the chamber 32 and terminating in a rounded seat 36 adjacent a flange 38 for mounting and securing in place an associated exhaust pipe, not shown.
At the other end of the housing, the chamber 32 is closed by a removable cap 40 secured to the cast housing 30 by bolts 42 and forming a part of the housing assembly. A gasket 44 is provided to seal the joint.
Within chamber 32 there is disposed an insulating liner 46 formed of high alumina ceramic or the like and having axially extending ribs 48 engaging the inner walls of the housing. The ribs maintain the remainder of the insulating liner in spaced relation with the housing walls to form insulating dead air spaces 50. Within the liner 46 a tubular metal catalytic element 52 extends longitudinally of the chamber 32 and is supported at one end within an opening 54 connecting the chamber 32 with the outlet passage 34. At the other end element 52 is supported by a cylindrical extension 56 of the cap 40. An annular ceramic ring 57 extends between liner 46 and element 52 to maintain element 52 in position upon removal of the cap 40.
The tubular catalytic element 52 divides the main portion of the chamber 32 within the liner 46 into inner and outer sections 58 and 60, respectively. A plurality of openings or perforations 62 extend over about two-thirds of the circumference of the tubular element 52 and longitudinally for its entire length to provide communication between the inner and outer chamber sections. A non-perforated extension of element 52, extending from the non-perforated portion thereof, forms a baffle 64 which extends into inlet openings 66 in the liner 46.
The openings 66 connect with inlet ports 68 formed in extensions of the housing 30 and connecting tangentially with the outer section 60 of the chamber. Ports 68 are connected at their outer ends with the engine exhaust ports 22.
Separate air-supply means are provided to supply air for mixture with the exhaust gases in both the inner and outer sections 58, 60 of the chamber to accomplish primary and secondary oxidation reactions. Introduction of primary reaction air to the outer section is accomplished through a longitudinal manifold passage 70 drilled in the housing 30 adjacent both the chamber 32 and the inlet ports 68. A plurality of runners 72 are drilled in the housing intersecting passage 70 and connecting it with the outer chamber portion at its juncture with the respective inlet ports 68. The outer ends of the drilled runners are closed by plugs 76. A threaded opening 78 in the cap 40 provides access to the passage 70 for the supply of air thereto from an external pump or other means.
The supply of secondary reaction air to the inner chamber section 58 is accomplished through a central chamber section 79 defined within inner section 58 by a longitudinally extending tubular distribution member 80 which is supported at opposite ends by the housing 30 and cap 40 and extends the length of the reaction chamber 32 on the axis thereof. One end of member 80 extends out through an opening 82 in the cap 40 for connection with an external source of air. Perforations 84 along the length of the tubular member 80 provide for the passage of air to all parts of the inner chamber section for mixture and reaction with exhaust gases therein.
In addition to the insulating liner 46, further insulation of the chamber walls may be provided, such as by annular ring 57 adjacent the cap 40. If desired, other portions of the housing wall and the inlet and exhaust passages may be insulated with inserts or other means to further reduce heat loss.
In operation, engine exhaust gases are directed through engine exhaust ports 22 to the C-R manifold inlet ports 68 by which they are directed tangentially into the outer section 60 of the housing chamber 32. Here they are mixed with air supplied by external means such as a pump, not shown, through the passage 70 and runners 72 and the mixture is directed in an annular swirling motion around the outer section 60 while undergoing an oxidation reaction. This primary oxidation reaction raises the exhaust gas temperature for the subsequent reduction step but the amount of air added is limited so that the oxidation of HC and CO is not completed and a reducing atmosphere is retained.
After moving past the non-perforated portions of element 52, the gases then pass through the perforated portions of the catalytic element 52 which is heated by the partially oxidized gases and aids in the reduction of NO x . Having moved through the element 52 into the inner chamber section 58, the exhaust gases are then mixed with additional air supplied through the perforated tube 80 and a secondary oxidation reaction takes place, thereby minimizing residual amounts of HC and CO as the gases pass through and out from the inner chamber portion 58 and through the outlet passage 34.
FIG. 4 of the drawings shows an alternative arrangement of an engine manifold assembly which is similar in many respects to the first described embodiment. To simplify description, comparable parts are identified by like numerals in the 400 series.
The differences in the embodiment of FIG. 4 from that previously described are as follows. The housing 430 includes a plurality of raised portions 431 extending inwardly of the wall portion defining chamber 432. Portions 431 act as turbulators to induce better mixing of the exhaust gases and air supplied to the chamber outer section 460. In addition, a separate insulating liner is dispensed with and in place thereof insulation 447, preferably of a ceramic type, is applied directly to the walls of the chamber and inlet ports 468. The air supply means also differ slightly in that the runners 472 from the primary air supply passage 470 open through the walls of the inlet ports 468 immediately adjacent their connection with the outer chamber section 460. In other ways, the construction and operation are generally the same as the embodiment of FIGS. 1 - 3.
FIG. 5 illustrates another embodiment of the invention in which components are identified by 500 series numbers, comparable numerals being used for parts similar to those of the previously described embodiments. In the FIG. 5 embodiment, the housing interior has directly applied insulation 547 similar to the embodiment of FIG. 4. The housing further includes a spiral baffle portion 565 which extends spirally between the juncture of the inlet ports 568 with the chamber 530 to the tubular element 552, replacing in function the metal baffle 64 formed as a part of the tubular element of the first embodiment.
The primary air supply of the embodiment of FIG. 5 is distributed from a manifold passage 570 located outside of the inlet passages 568 and connected to them by runners 572 intersecting the outer walls of the inlet passages 568 adjacent their points of entry into the main chamber 530. The runners are drilled and closed by plugs 576 in a manner similar to the previously described embodiments.
The embodiments of FIGS. 6 - 9 differ from those previously described in that the primary reaction zones are inside the secondary reaction zones of the chamber. This difference results in a number of differences in the constructions to be described below.
In FIG. 6, the portion of housing 630 defining chamber 632 has spaced concentrically therein an insulating liner 646 and a tubular metal element 652. The liner 646 includes spaced rib portions 648 which maintain the main body of the liner in spaced relation with the housing walls 630 so as to define a peripheral air supply space 651 connected by means, not shown, with an external supply of air. A plurality of circumferentially and longitudinally spaced openings 647 in the liner 646 provide for the passage of air from the peripheral space 651 into the adjacent outer section 660 of the chamber 632.
Tubular member 652 divides the main portion of chamber 632 into inner and outer sections 658 and 660, respectively. Outer section 660 connects with outlet openings 661 in the end wall to provide for the passage of treated exhaust gases. Inner section 658 is connected with inlet ports 668 provided in the housing and the engine exhaust ports 622 by a baffle extension 653 extending from the tubular element 642 and by a separate baffle member 688 which extends from openings 666 in the insulating member through openings 655 in the element 652 to a rolled edge portion 690 extending to the center of the chamber 630. These baffle members guide entering exhaust gases through the outer section 660 and tangentially into the inner section 658, where they pass approximately halfway around the inner section before reaching a portion of the tubular element 652, having perforations 662 through which gases may pass through to the outer section 660. In the latter section, the gases are mixed with air passing from the peripheral air space 651 entering the outer section through openings 647.
Primary reaction air is supplied directly to the engine exhaust ports 622 through an external air manifold 671 which supplies individual air tubes 673 extending into each of the engine exhaust ports 622. The primary oxidation reaction thus begins in the engine exhaust ports 622 and continues in the inlet ports 668 and the chamber inner section 658. Secondary reaction air is supplied through peripheral air space 651 and openings 647 directly to the outer portion 660 of the chamber where the secondary oxidation reactions are initiated.
The embodiment of FIG. 7 is generally similar to that of FIG. 6, except that the cylinder head and C-R manifold housing are modified to provide for primary and secondary air supply through a drilled manifold passage 771 extending longitudinally within the cylinder head. Passage 771 connects with runners 773 extending directly to each of the engine exhaust ports 722 to supply primary air thereto. Passage 771 also connects with runners 792 which connect in turn with air inlet openings 793 through the housing mounting surface. Openings 793 connect directly with the air supply space 751 between the perforated insulator 746 and the outer wall of the housing 730. In this manner, secondary air is also supplied from the manifold passage 771.
In FIG. 8, the construction differs from that of FIg. 7 in that a cylindrical recess 894 is provided in the cylinder head mounting face surrounding the engine exhaust ports 822. The runners 873 supply this recess with air from drilled manifold passage 871. A cylindrical extension 895 of the mounting portion of housing 830 extends into recess 894 but spaced from the end thereof so as to provide an annular air chamber 896 from which air is supplied peripherally to the exhaust ports 822 and mixed with the exhaust gases. The baffle member 888 in the FIG. 8 construction utilizes a smaller rolled edge portion 890 than in the previously described constructions.
In FIG. 9 the arrangement is generally similar to that of FIG. 8, differing, however, in that the connection of the engine exhaust passages 922 with the inner section 958 of the reaction chamber is through a tubular ceramic member 997 which extends inwardly to the axis of the chamber, replacing previous baffle members, and outwardly into the recess 994 in the cylinder head, replacing the housing extension. The ceramic tubes 997 are fitted snugly within the openings 966 and 955 respectively, provided in the tubular insulating member 946 and the perforated tubular catalytic element 952.
While the catalytic elements illustrated in the various embodiments of the subject invention have been shown as single layers of tubular metal having perforations in portions thereof, it would be within the scope of the invention to substitute several layers of metal screen or mesh or multiple perforated metal members to provide an extended travel path for gases in contact with the catalytic NO x -reducing element. In addition, it is contemplated that numerous other changes may be made in the embodiments described without departing from the spirit and scope of the invention which is, accordingly, intended to be limited only by the language of the following claims.
This invention relates to arrangements of exhaust manifold converter-reactors (C-R's) for internal combustion engines and, more particularly, to C-R manifold arrangements for attachment to and in combination with internal combustion engines.
It is known in the art to provide an internal combustion engine with a converter-reactor (C-R) system for minimizing hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NO x ) in the exhaust gases. Some such systems have involved three operational stages which may take place in separate or combined units, the stages including (1) a primary stage of partial oxidation of HC and CO with added or excess air which heats the gases while maintaining a reducing atmosphere, (2) an intermediate stage of NO x reduction wherein the heated gases from the primary stage are passed through a catalytic element consisting of wire screen or mesh such as copper-clad steel, stainless steel or the like, and (3) a secondary oxidizing stage wherein additional air is added to react with remaining HC and CO in the exhaust gases.
SUMMARY OF THE INVENTION
The present invention provides a family of C-R manifold arrangements for use on and in combination with internal combustion engines and including the common features of concentric primary and secondary oxidizing zones separated by a cylindrical catalytic element for reducing NO x , all combined in a single manifold unit. Means are provided for supplying oxidizing air to both the primary and secondary zones and for insulating the C-R housing against excessive heat loss. The inner and outer sections defined by the catalytic element within the C-R housing may in alternative arrangements comprise either the primary or secondary reaction zones. In either case, exhaust gas inlet ports direct gas tangentially into the primary zone to provide a swirl motion which promotes extended residence time.
These and other features and advantages of the invention will be more fully appreciated and understood by the following description of certain specific arrangements of C-R manifolds formed according to the invention and selected for illustrative purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a side view of a portion of an internal combustion engine having installed thereon a C-R manifold formed according to the invention;
FIG. 2 is a fragmentary end view of the engine of FIG. 1 showing the attached C-R manifold;
FIG. 3 is a cross-sectional view of the engine of FIGS. 1 and 2 taken generally in the plane indicated by the Line 3--3 of FIG. 1; and
FIGS. 4 - 9 are cross-sectional views similar to FIG. 3 but showing various alternative arrangements of engine C-R manifold assemblies.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Referring first to FIGS. 1 - 3 of the drawings, there is shown an internal combustion engine generally indicated by numeral 10. Engine 10 includes the usual cylinder block 12 containing a plurality of cylinders 14 having pistons 16 reciprocably mounted therein. Cylinders 14 are conventionally closed by a cylinder head 18 having inlet valves, not shown, and exhaust valves 20 openable to communicate their respective cylinders 14 with associated exhaust ports 22 formed within the cylinder head 18.
On the side of the cylinder head there are exhaust manifold mounting faces 24 through which the exhaust ports 22 open and to which a C-R manifold generally indicated by numeral 26 is secured by means such as bolts 28 or the like.
Manifold 26 comprises a cast, generally tubular housing 30 extending longitudinally of the engine and enclosing an elongated cylindrical chamber 32. At one end of the housing 30 a downwardly directed outlet passage 34 is formed, connecting with the central portion of the chamber 32 and terminating in a rounded seat 36 adjacent a flange 38 for mounting and securing in place an associated exhaust pipe, not shown.
At the other end of the housing, the chamber 32 is closed by a removable cap 40 secured to the cast housing 30 by bolts 42 and forming a part of the housing assembly. A gasket 44 is provided to seal the joint.
Within chamber 32 there is disposed an insulating liner 46 formed of high alumina ceramic or the like and having axially extending ribs 48 engaging the inner walls of the housing. The ribs maintain the remainder of the insulating liner in spaced relation with the housing walls to form insulating dead air spaces 50. Within the liner 46 a tubular metal catalytic element 52 extends longitudinally of the chamber 32 and is supported at one end within an opening 54 connecting the chamber 32 with the outlet passage 34. At the other end element 52 is supported by a cylindrical extension 56 of the cap 40. An annular ceramic ring 57 extends between liner 46 and element 52 to maintain element 52 in position upon removal of the cap 40.
The tubular catalytic element 52 divides the main portion of the chamber 32 within the liner 46 into inner and outer sections 58 and 60, respectively. A plurality of openings or perforations 62 extend over about two-thirds of the circumference of the tubular element 52 and longitudinally for its entire length to provide communication between the inner and outer chamber sections. A non-perforated extension of element 52, extending from the non-perforated portion thereof, forms a baffle 64 which extends into inlet openings 66 in the liner 46.
The openings 66 connect with inlet ports 68 formed in extensions of the housing 30 and connecting tangentially with the outer section 60 of the chamber. Ports 68 are connected at their outer ends with the engine exhaust ports 22.
Separate air-supply means are provided to supply air for mixture with the exhaust gases in both the inner and outer sections 58, 60 of the chamber to accomplish primary and secondary oxidation reactions. Introduction of primary reaction air to the outer section is accomplished through a longitudinal manifold passage 70 drilled in the housing 30 adjacent both the chamber 32 and the inlet ports 68. A plurality of runners 72 are drilled in the housing intersecting passage 70 and connecting it with the outer chamber portion at its juncture with the respective inlet ports 68. The outer ends of the drilled runners are closed by plugs 76. A threaded opening 78 in the cap 40 provides access to the passage 70 for the supply of air thereto from an external pump or other means.
The supply of secondary reaction air to the inner chamber section 58 is accomplished through a central chamber section 79 defined within inner section 58 by a longitudinally extending tubular distribution member 80 which is supported at opposite ends by the housing 30 and cap 40 and extends the length of the reaction chamber 32 on the axis thereof. One end of member 80 extends out through an opening 82 in the cap 40 for connection with an external source of air. Perforations 84 along the length of the tubular member 80 provide for the passage of air to all parts of the inner chamber section for mixture and reaction with exhaust gases therein.
In addition to the insulating liner 46, further insulation of the chamber walls may be provided, such as by annular ring 57 adjacent the cap 40. If desired, other portions of the housing wall and the inlet and exhaust passages may be insulated with inserts or other means to further reduce heat loss.
In operation, engine exhaust gases are directed through engine exhaust ports 22 to the C-R manifold inlet ports 68 by which they are directed tangentially into the outer section 60 of the housing chamber 32. Here they are mixed with air supplied by external means such as a pump, not shown, through the passage 70 and runners 72 and the mixture is directed in an annular swirling motion around the outer section 60 while undergoing an oxidation reaction. This primary oxidation reaction raises the exhaust gas temperature for the subsequent reduction step but the amount of air added is limited so that the oxidation of HC and CO is not completed and a reducing atmosphere is retained.
After moving past the non-perforated portions of element 52, the gases then pass through the perforated portions of the catalytic element 52 which is heated by the partially oxidized gases and aids in the reduction of NO x . Having moved through the element 52 into the inner chamber section 58, the exhaust gases are then mixed with additional air supplied through the perforated tube 80 and a secondary oxidation reaction takes place, thereby minimizing residual amounts of HC and CO as the gases pass through and out from the inner chamber portion 58 and through the outlet passage 34.
FIG. 4 of the drawings shows an alternative arrangement of an engine manifold assembly which is similar in many respects to the first described embodiment. To simplify description, comparable parts are identified by like numerals in the 400 series.
The differences in the embodiment of FIG. 4 from that previously described are as follows. The housing 430 includes a plurality of raised portions 431 extending inwardly of the wall portion defining chamber 432. Portions 431 act as turbulators to induce better mixing of the exhaust gases and air supplied to the chamber outer section 460. In addition, a separate insulating liner is dispensed with and in place thereof insulation 447, preferably of a ceramic type, is applied directly to the walls of the chamber and inlet ports 468. The air supply means also differ slightly in that the runners 472 from the primary air supply passage 470 open through the walls of the inlet ports 468 immediately adjacent their connection with the outer chamber section 460. In other ways, the construction and operation are generally the same as the embodiment of FIGS. 1 - 3.
FIG. 5 illustrates another embodiment of the invention in which components are identified by 500 series numbers, comparable numerals being used for parts similar to those of the previously described embodiments. In the FIG. 5 embodiment, the housing interior has directly applied insulation 547 similar to the embodiment of FIG. 4. The housing further includes a spiral baffle portion 565 which extends spirally between the juncture of the inlet ports 568 with the chamber 530 to the tubular element 552, replacing in function the metal baffle 64 formed as a part of the tubular element of the first embodiment.
The primary air supply of the embodiment of FIG. 5 is distributed from a manifold passage 570 located outside of the inlet passages 568 and connected to them by runners 572 intersecting the outer walls of the inlet passages 568 adjacent their points of entry into the main chamber 530. The runners are drilled and closed by plugs 576 in a manner similar to the previously described embodiments.
The embodiments of FIGS. 6 - 9 differ from those previously described in that the primary reaction zones are inside the secondary reaction zones of the chamber. This difference results in a number of differences in the constructions to be described below.
In FIG. 6, the portion of housing 630 defining chamber 632 has spaced concentrically therein an insulating liner 646 and a tubular metal element 652. The liner 646 includes spaced rib portions 648 which maintain the main body of the liner in spaced relation with the housing walls 630 so as to define a peripheral air supply space 651 connected by means, not shown, with an external supply of air. A plurality of circumferentially and longitudinally spaced openings 647 in the liner 646 provide for the passage of air from the peripheral space 651 into the adjacent outer section 660 of the chamber 632.
Tubular member 652 divides the main portion of chamber 632 into inner and outer sections 658 and 660, respectively. Outer section 660 connects with outlet openings 661 in the end wall to provide for the passage of treated exhaust gases. Inner section 658 is connected with inlet ports 668 provided in the housing and the engine exhaust ports 622 by a baffle extension 653 extending from the tubular element 642 and by a separate baffle member 688 which extends from openings 666 in the insulating member through openings 655 in the element 652 to a rolled edge portion 690 extending to the center of the chamber 630. These baffle members guide entering exhaust gases through the outer section 660 and tangentially into the inner section 658, where they pass approximately halfway around the inner section before reaching a portion of the tubular element 652, having perforations 662 through which gases may pass through to the outer section 660. In the latter section, the gases are mixed with air passing from the peripheral air space 651 entering the outer section through openings 647.
Primary reaction air is supplied directly to the engine exhaust ports 622 through an external air manifold 671 which supplies individual air tubes 673 extending into each of the engine exhaust ports 622. The primary oxidation reaction thus begins in the engine exhaust ports 622 and continues in the inlet ports 668 and the chamber inner section 658. Secondary reaction air is supplied through peripheral air space 651 and openings 647 directly to the outer portion 660 of the chamber where the secondary oxidation reactions are initiated.
The embodiment of FIG. 7 is generally similar to that of FIG. 6, except that the cylinder head and C-R manifold housing are modified to provide for primary and secondary air supply through a drilled manifold passage 771 extending longitudinally within the cylinder head. Passage 771 connects with runners 773 extending directly to each of the engine exhaust ports 722 to supply primary air thereto. Passage 771 also connects with runners 792 which connect in turn with air inlet openings 793 through the housing mounting surface. Openings 793 connect directly with the air supply space 751 between the perforated insulator 746 and the outer wall of the housing 730. In this manner, secondary air is also supplied from the manifold passage 771.
In FIG. 8, the construction differs from that of FIg. 7 in that a cylindrical recess 894 is provided in the cylinder head mounting face surrounding the engine exhaust ports 822. The runners 873 supply this recess with air from drilled manifold passage 871. A cylindrical extension 895 of the mounting portion of housing 830 extends into recess 894 but spaced from the end thereof so as to provide an annular air chamber 896 from which air is supplied peripherally to the exhaust ports 822 and mixed with the exhaust gases. The baffle member 888 in the FIG. 8 construction utilizes a smaller rolled edge portion 890 than in the previously described constructions.
In FIG. 9 the arrangement is generally similar to that of FIG. 8, differing, however, in that the connection of the engine exhaust passages 922 with the inner section 958 of the reaction chamber is through a tubular ceramic member 997 which extends inwardly to the axis of the chamber, replacing previous baffle members, and outwardly into the recess 994 in the cylinder head, replacing the housing extension. The ceramic tubes 997 are fitted snugly within the openings 966 and 955 respectively, provided in the tubular insulating member 946 and the perforated tubular catalytic element 952.
While the catalytic elements illustrated in the various embodiments of the subject invention have been shown as single layers of tubular metal having perforations in portions thereof, it would be within the scope of the invention to substitute several layers of metal screen or mesh or multiple perforated metal members to provide an extended travel path for gases in contact with the catalytic NO x -reducing element. In addition, it is contemplated that numerous other changes may be made in the embodiments described without departing from the spirit and scope of the invention which is, accordingly, intended to be limited only by the language of the following claims.