WO2000010690A1

WO2000010690A1 - Pre-catalytic converter and catalytic converter combination

Info

Publication number: WO2000010690A1
Application number: PCT/US1999/018345
Authority: WO
Inventors: Gregory M. Marocco
Original assignee: Marocco Gregory M
Priority date: 1998-08-18
Filing date: 1999-08-13
Publication date: 2000-03-02
Also published as: AU5673499A

Abstract

A pre-catalytic converter and catalytic converter combination (10) is contained within a common canister or shell (12). The converter combination (10) is adapted for installation immediately adjacent an internal combustion engine, or as close as is practicable thereto, in order to provide the maximum possible exhaust temperature and heat transfer to the converter elements (22, 24). The upstream element (relative to the engine exhaust flow) comprises a pre-catalytic converter (22) with the foremost portion (36) thereof containing a relatively high concentration of noble metals and/or other catalytic elements. Preferably, the substrates (28, 30) of the two converter elements (22, 24) are formed of a strong and heat resistant material. The present pre-catalytic converter and catalytic converter combination (10) provides a significant increase in efficiency in comparison to such devices of the prior art.

Description

PRE-CATALYTIC CONVERTER AND CATALYTIC CONVERTER

COMBINATION 1. FIELD OF THE INVENTION

The present invention relates generally to automobile exhaust emission control, and more specifically to a device combining a catalytic exhaust converter and pre-catalytic converter into a single unit. The device is placed as closely as possible to the engine, in order to receive the engine exhaust at as high a temperature as possible. Various improvements in the art are provided in at least the pre-catalytic converter unit, in order to absorb the higher exhaust heat due to placement of the device relatively close to the engine. 2. DESCRIPTION OF THE RELATED ART

By the time of the 1950s, it was becoming apparent that the ever increasing volume of automobile and truck traffic was generating exhaust emissions which were adversely affecting the environment. This was particularly true in urban areas and other areas where geographic and meteorological conditions combined to create areas where such emissions do not readily dissipate. Accordingly, by the late 1960s, various regulations were being implemented to require equipment to reduce exhaust emissions output from automobiles, particularly in. California and other urban areas .

While early emissions control efforts provided some relief, standards have become increasingly strict in order to keep pace with the ever increasing volume of automobile and truck traffic throughout the U. S. A. With the development of the catalytic converter, which uses one or more noble metals such as platinum, rhodium, and/or palladium to produce an oxidizing and/or reducing catalytic reaction with the exhaust products and heat generated by the exhaust, a real breakthrough was achieved in the control of vehicle emissions. An automobile equipped with one or more catalytic converters was capable of meeting most, if not all, of the exhaust emissions standards of the time, and the use of catalytic converters became commonplace on automobiles and light trucks powered by spark ignition engines in the U. S. A.

However, such converters are not without their limitations and drawbacks. The fuels used in automobile engines equipped with such converters are limited as to the additives they may contain, in order to preclude damage to the converters which would render them ineffective in short order. Also, the efficiency of the catalytic reactions is based to a great extent upon the heat output of the exhaust system. While the catalytic reactions themselves generate an appreciable amount of heat, at least some initial heat is required to initiate the reactions, and generally speaking, the greater the heat of the catalytic reaction, the more efficient the catalytic converter will be.

However, catalytic converters to this point have generally been limited in the amount of heat which they are capable of handling, due to the materials from which they are constructed. The substrate, or open grid or honeycomb structure which is coated with the noble metals which generate the catalytic reactions, has been formed of metal which has limits as to the temperature which it is capable of handling. While it is possible to increase the thickness and mass of the metal substrate, this has the effect of reducing the size of the passages therein through which the exhaust passes, thus decreasing the efficiency of the converter. Thinner metals are prone to buckling and distorting due to the heat within the converter, which also has the effect of reducing flow through the converter. These factors have seriously limited the placement of catalytic converters in close proximity to the engine itself, due to the additional heat which would be received by the converter in such a location. While the catalytic reactions would be more efficient, and this increase in efficiency has led to the development of the pre-catalytic converter upstream of the primary converter, such pre-catalytic converters to this point have been relatively costly due to the relatively exotic materials required, and have been of limited efficiency due to the need to limit the maximum size in order to limit the heat buildup therein.

Accordingly, a need will be seen for a pre-catalytic converter which responds to the above described problems, and which may be placed with another catalytic converter immediately downstream therefrom. The two converters are housed within the same container or shell, in order to provide manufacturing efficiency and further to provide the maximum amount of heat transfer between the pre-catalytic converter and the catalytic converter in order to provide the greatest efficiency in the catalytic reactions therein. A novel construction is provided for at least the pre-catalytic converter, in order to increase the . efficiency of the exhaust flow therethrough, as well as to preclude damage to the device due to heat. A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.

U. S. Patent No. 4,425,304 issued on January 10, 1984 to Masayuki Kawata et al . describes a Catalytic Converter comprising a single shell or container with two converter units or "bricks" installed in series therein. A spacer assembly incorporating an air pipe is installed between the two converter units, to supply additional oxygen to a downstream reducing catalytic converter. Kawata et al . are silent regarding the location of their converter unit relative to the internal combustion engine with which it is to be used, and no special construction is disclosed for a pre-catalytic converter to enable it to handle the heat generated by the close proximity of the engine and its relatively hot exhaust, as provided by the present invention. U. S. Patent No. 4,426,844 issued on January 24,

1984 to Keiichi Nakano describes an Engine Muffler Of Heat-Exchanging Type, incorporating a pair of catalytic converter components therein. Nakano is silent regarding any specialized construction of the converters themselves to handle excessive heat, and/or any specialized treatment of either of the converters for use as a pre-catalytic converter, as in the present invention. While Nakano discloses the use of a ceramic material in his invention, the ceramic is used only for insulation, and not in either of the catalytic converters themselves, as is the case in the present invention.

U. S. Patent No. 4,536,371 issued on August 20, 1985 to Timothy Z. Thayer et al . describes a Catalytic Converter Divider for separating a forward and a rearward catalytic converter component within the converter shell. Thayer et al . are silent regarding any specialized construction of the catalytic converters themselves to allow at least one to serve as a pre-catalytic converter within the shell, as provided by the present invention.

U. S. Patent No. 5,043,147 issued on August 27, 1991 to Glen Knight describes a Combined Muffler And Catalytic Converter Exhaust Unit, with a pair of converters being installed within the first portion of the muffler shell. Exhaust gases pass through the converters before passing through the muffler portion of the unit. As the device must be located relatively far from the engine, the exhaust temperatures are not sufficient to require any specialized converter configuration, as provided by the present invention. U. S. Patent No. 5,108,716 issued on April 28, 1992 to Kimiyoshi Nishizawa describes a Catalytic Converter having two converter components housed within a single container or shell. The present pre-catalytic and catalytic converter combination utilizes a similar housing or shell, but there are significant differences between the Nishizawa converter and the present invention. Nishizawa recognizes the need for elevated temperatures within the converter in order to promote efficient conversion reactions of the exhaust gases, and accordingly provides a higher concentration of catalytic metals in the first or upstream converter than in the downstream converter. This has the effect of increasing the catalytic reactions in that converter, thereby increasing the heat output and further increasing the catalytic reactions occurring. However, Nishizawa provides the increased catalytic metal density throughout his first converter, rather than only in the first portion thereof, as in the present invention. Also, Nishizawa provides a lower cell density in the first converter than in the second, thus causing the second converter to produce some increased back pressure. In addition, Nishizawa is silent regarding the placement of his converter as closely as possible to the engine in order to take advantage of relatively high exhaust temperatures therefrom, as provided by the present converter combination. The present converter combination uses a relatively low cell density and thin cell walls in both converters, in order to reduce back pressure through the system and promote the flow of exhaust gases therethrough. U. S. Patent No. 5,265,420 issued on November 30, 1993 to Erwin Rutschmann describes an Exhaust System Of A Multi-Cylinder Reciprocating Engine, in which a single catalytic converter is provided for each cylinder bank of a V-8 engine. The converters do not comprise a dual system of pre-catalytic and catalytic converter for each cylinder bank, as in the present invention. (The band dividing the single converter on each side appears to represent an attachment means for securing the converters into their respective housings or shells.) Each converter is installed some distance downstream from the actual engine, as evidenced by the multiple tube exhaust manifold which combines into a single exhaust pipe for each side, at the end of which is located each respective converter, after each exhaust passage has made a 180 degree turn. Rutschmann is silent regarding any combinations of catalytic converters, or their specific configurations . U. S. Patent No. 5,325,666 issued on July 5, 1994 to

Erwin Rutschmann describes an Exhaust System Of An Internal Combustion Engine, somewhat similar to the apparatus of the '420 U. S. Patent to the same inventor, discussed immediately above. However, the assembly of the '666 Patent provides additional catalytic converters in place of the transverse muffler of the '420 Patent. Additional converters are provided upstream of these main converters, through which flow is selectively provided depending upon the temperature of the main converters. Rutschmann also mentions individual converters at each cylinder, with the total assembly creating considerable back pressure and complexity.

U. S. Patent No. 5,378,435 issued on January 3, 1995 to Albino Gavoni describes a Silencer Combined With Catalytic Converter For Internal Combustion Engines And Modular Diaphragm Elements For Said Silencer. The device is essentially a cylindrical container with a series of cup-shaped catalytic converter elements arranged therein. The elements are each relatively thin, due to the cup-like shape of each element, and thus do not present a significant cross sectional area to the exhaust gases passing therethrough. Thus, a great many such elements are required, unlike the present pre-catalytic converter and catalytic converter combination. Moreover, with the relatively thin elements and the relatively large distance provided between each one, the catalytic reaction efficiency would appear to be poor, due to the difficulty in retaining heat in each element. The present converter combination utilizes relatively large converter elements, and positions them immediately adjacent the engine, to optimize temperatures and reaction efficiency.

U. S. Patent No. 5,398,504 issued on March 31, 1995 to Tomotaka Hirota et al . describes a Layout Structure Of Catalytic Converters, in which first and second converters are installed immediately adjacent the respective cylinder banks of a V-configuration engine. The main converter is installed beneath the engine and downstream (relative to the exhaust flow) from the first and second converters . Hirota et al . do not place the pre-catalytic converters and catalytic converter within the same shell, as is done with the present system.

Japanese Patent Publication No. 55-43262 published on March 27, 1980 illustrates an exhaust gas purifier in which the catalytic converter unit includes a baffle within its inlet end to preclude interference between exhaust gases alternatingly entering the converter from the no. 1 and no. 4 cylinders, and the no. 2 and no. 3 cylinders. The converter is not installed immediately adjacent the engine, but rather is installed at the outlet end of an exhaust header. The number of catalytic units in the converter unit is not apparent .

Finally, Japanese Patent Publication No. 57-41414 published on March 8, 1982 illustrates a method of manufacturing a catalytic converter equipped with a muffler. The assembly includes a forward muffler with a catalytic converter welded thereto and downstream thereof, with a rear muffler welded to the downstream end of the catalytic converter. Thus, the catalytic converter must be positioned somewhat remotely from the engine, since the front muffler is installed upstream of the converter, i. e., between the engine and the converter. No disclosure of converter properties, or of multiple converters, is apparent in the Japanese 41414 publication.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.

SUMMARY OF THE INVENTION The present invention comprises a pre-catalytic converter and catalytic converter combination, combined within a single canister or shell. As a pre- catalytic converter, the device provides for installation immediately adjacent an internal combustion engine, or as close as is practicable to the engine, in order to receive the hottest possible exhaust gas flow therefrom. The device includes two catalytic converter elements therein, arranged in series. The first or pre-catalytic converter element includes a "hot face," or additional catalytic material disposed at the front portion thereof. The rapid warmup of the pre-catalytic converter element due to its proximity to the engine, along with the additional catalytic material density in the foremost portion thereof, provides a relatively hot reaction which aids the efficiency of the pre-catalytic element . The relatively hot exhaust gases then pass to another catalytic converter element immediately downstream of the pre-catalytic converter element. The exhaust gases are still relatively hot, due to their proximity to the engine and also due to the heat generated by the catalytic reaction within the pre- catalytic converter. This assists in quickly warming the downstream catalytic converter, and also in maintaining a relatively high temperature therein in order to provide optimum efficiency in the catalytic reaction therein.

Due to the relatively high heat obtained within the present pre-catalytic converter and catalytic converter combination, ordinary metals may not be suitable for use as the substrate for the converter elements. Preferably, the substrate "honeycomb" or "grid" structure of each converter is formed of a ceramic material to withstand the high heat generated. A ceramic material known as Dow-Corning XT (tm) , manufactured by the Dow-Corning Company, has been found to be suitable for use for the substrate of the present converters. The Dow-Corning XT ceramic is relatively strong, and allows the grid walls of the substrate to be made relatively thin, and for the passages through the grid to be made relatively larger,, than in other catalytic converters previously known. This provides a relatively high surface area for the wall thickness of the material, thus increasing efficiency, and further reduces internal resistance to flow, thus allowing the system to "breathe" more freely to increase the efficiency of the engine and vehicle.

Accordingly, it is a principal object of the invention to provide an improved pre-catalytic converter and catalytic converter combination for installing immediately adjacent an internal combustion engine, for transferring the maximum amount of exhaust heat from the engine to the pre-catalytic converter.

It is another object of the invention to provide an improved pre-catalytic converter and catalytic converter combination which includes a relatively high concentration of catalytically reactive elements and materials disposed on and within the foremost portion of the pre-catalytic converter element.

It is a further object of the invention to provide an improved pre-catalytic converter and catalytic converter combination which includes substrate elements having relatively thin walls and relatively large passages therethrough, for providing the maximum surface area for the amount of solid volume within the converters and for minimizing flow resistance therethrough .

An additional object of the invention is to provide an improved catalytic converter and pre-catalytic converter combination which substrate elements are formed of a strong and heat resistant ceramic material .

Still another object of the invention is to provide an improved catalytic converter and pre-catalytic converter combination which pre-catalytic converter and catalytic converter elements are immediately adjacent, or in close proximity, to one another within the single canister or shell, for providing the maximum heat transfer from the pre-catalytic converter element to the catalytic converter element therein. It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes . These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view in partial section of a pre-catalytic converter and catalytic converter incorporating elements of the present invention. Figure 2 is a detailed side elevation view in section of the forwardmost portion of the pre- catalytic converter element of the present invention, showing the increased density of catalytic materials therein. Figure 3 is a detailed front elevation view of the substrate element and flow passages therethrough of the present pre-catalytic and catalytic converter elements, showing the thinner walls and larger passages therethrough. Figure 4 is a detailed front elevation view of a prior art substrate element for a catalytic converter, showing the relatively thick walls and narrow passages therethrough.

Figure 5 is a flow chart illustrating the exhaust flow path from the engine through the present pre- catalytic converter and catalytic converter combination, along with other elements of an exhaust system, and diagrammatically illustrating the proximity of the pre-catalytic converter and catalytic converter combination to the engine.

Similar reference characters denote corresponding features consistently throughout the attached drawings .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is a pre-catalytic converter and catalytic converter combination, indicated by the reference numeral 10 in Figures 1 and 5. The present catalytic converter combination 10 may be used at any practicable point in the exhaust system of an internal combustion engine. However, due to its specific configuration, it is particularly well suited for installation immediately adjacent, or in close proximity, to the engine, preferably at the exhaust manifold where the manifold reduces down to a single pipe or outlet.

A canister 12 includes an inlet end 14, a forward portion 16, a rearward portion 18, and an outlet end 20. These portions of the canister 12 are arranged linearly, with the forward portion 16 adjacent the inlet end 14, the rearward portion 18 adjacent the forward portion 16, and the outlet end 20 adjacent the rearward portion 18. A pre-catalytic converter element 22 is installed in the forward portion 16 of canister 12, with a catalytic converter element 24 installed within the rear portion 18 of the canister 12. Preferably, the pre-catalytic and catalytic converter elements 22 and 24 are situated immediately adjacent or in close proximity to one another with no more than a very small passage 26 therebetween. This permits heat generated by the first converter element 22 to be transferred to the second converter element 24 with a minimal loss, and for the engine exhaust passing to the second catalytic converter element 24 to retain as much heat as possible in order to accelerate the catalytic reaction therein as much as possible . Both the pre-catalytic converter element 22 and catalytic converter . element 24 are formed of a substrate, respectively 28 and 30, each having a plurality of longitudinal passages 32 therethrough, with each of the passages 32 being defined by a plurality of walls 34. (Only a portion of the two substrates 28 and 30 is shown schematically in Figure 1, with Figures 2 and 3 providing detailed views of the substrate structure.) These walls 34 may be generally horizontally and vertically oriented, or otherwise oriented to form a honeycomb or grid-like configuration when viewed in lateral cross section, as shown in Figure 3. Each of the walls 34 is coated with one or more catalytically reactive elements or materials, e. g., noble metals such as platinum, palladium, rhodium, etc., as is known in the art.

However, the pre-catalytic converter element 22 is specially treated or coated, in order to take advantage of its close proximity to the engine and the relatively high heat output from the engine exhaust at that location. The pre-catalytic converter element 22 includes a foremost portion 36 and a remaining portion 38 therebehind, which comprises the balance of the pre-catalytic converter element 22. Preferably, the foremost portion 36 of the pre-catalytic converter element 22 is more heavily coated with catalytic elements than the remaining portion 38 and the second catalytic converter element 24, in order to react a greater amount of the exhaust gases at their highest heat level as they first enter the present pre- catalytic converter and catalytic converter combination 10. This higher concentration of catalyticaly reactive elements disposed within the foremost portion 36 of the pre-catalytic converter element 22, as indicated by the relatively heavier shading or stippling on the foremost portion 36 of the pre-catalytic converter element 22 shown in Figure 2, thus provides an increased catalytic reaction to react more of the exhaust gases as they first enter the foremost portion 36 of the pre-catalytic converter element 22. In addition to the relatively high exhaust gas temperatures, the catalytic reactions themselves serve to increase the temperature within the unit, thus further increasing the efficiency of the catalytic reaction.

The elevated temperatures provided by the reactions within the pre-catalytic converter 22 serve to heat the exhaust gases further, thus increasing the efficiency of the catalytic reactions in the secondary or catalytic converter element 24 when the exhaust gases reach that portion of the combination 10. The close proximity of the second catalytic converter element 24 to the first pre-catalytic converter element 22, and the close placement of the combination 10 to the engine itself, serve to maintain a relatively high exhaust gas temperature throughout the entire apparatus and through both converter elements 22 and 24, thus increasing the efficiency of the converter combination 10 and providing a cleaner engine exhaust output .

The efficiency of the present pre-catalytic converter and catalytic converter combination 10 is further increased by constructing the substrates 28 and 30 with the walls 34 having a relatively thin cross section and the passages 32 therebetween being relatively wide, in order to reduce the restriction to exhaust gas flow as much as possible. A comparison of the present substrate, e. g., substrate 30 of the second or catalytic converter element 24 of Figure 3, with a prior art substrate S shown in Figure 4 , clearly shows the wider passages 32 of the present substrate 30. (It should be understood that the two substrates 28 and 30 respectively of the pre-catalytic converter element 22 and of the catalytic converter element 24 are essentially identical dimensionally, with both having relatively large passages 32 and thin walls 34. The second converter substrate 30 is shown in Figure 3, as Figure 2 shows a longitudinal cross section of the first substrate 28.)

The walls W of conventional substrates, such as the substrate S shown in Figure 4, are relatively thick due to the need for structural strength at the elevated temperatures occurring within catalytic converters. These walls W are normally somewhat thicker than required for structural strength at normal temperatures, but due to the extremely elevated temperatures occurring within a catalytic converter, they must be made even thicker in order to provide the required structural strength at such elevated temperatures where most materials are weakened. The relative thickness of the walls W of conventional catalytic converter substrates S results in the passages P therebetween having a relatively narrow width, as may be seen in a comparison of a conventional catalytic converter substrate cross section in Figure 4 and the substrate 30 of the present catalytic converter invention. Typically, such conventional passages P have a width on the order of .040 inch, for a passage cross sectional area of about .0016 inch. Wider passages, with the walls therebetween being spread further apart, would not provide the required structural strength at the elevated temperatures occurring within such conventional catalytic converters.

On the other hand, the present pre-catalytic converter and catalytic converter substrates 28 and 30 each have passage widths substantially greater than .040 inch, preferably on the order of .050 inch for a passage cross sectional area of .0025 inch, or over half again as great an area as the conventional catalytic converter passage P. Yet, the number of passages 32 in a given cross sectional area of the present substrates 28 and 30 closely approaches that of the passages P in a conventional converter substrate S, due to the relatively thin substrate walls 34 of the present converter substrates 28 and 30. Due to their relatively high surface area per mass and volume ratio, the thin substrate walls 34 serve to absorb heat more quickly than the relatively thick walls W of prior art substrates S. This allows the present pre-catalytic converter element 22 and catalytic converter element 24 to reach their normal operating temperatures more quickly than catalytic converters of the prior art, thus reducing the "cold start" period when emissions are relatively high due to the need for exhaust gases to warm up the converter (s) to reach an optimum temperature for the catalytic reactions to occur efficiently. Thus, the present pre-catalytic converter and catalytic converter combination 10 reduces the period of time following a cold start when exhaust emissions are relatively high due to the catalytic converter (s) being relatively cool.

While conventional converter substrates S have been formed of relatively expensive metals in order to provide the required structural strength at the elevated temperatures found in such devices, the present pre-catalytic converter and catalytic converter combination 10 preferably uses a ceramic material for the substrate walls 34. Such ceramic materials provide excellent resistance to heat, but a relatively strong material is required in order to provide the required structural strength, particularly in the case of the relatively thin substrate walls 34 of the present invention. A ceramic material known as Dow-Corning XT (tm) , manufactured by the Dow-Corning Company, has been found to be suitable for the construction of such thin wall substrates 28 and 30 of the present invention. Other materials providing sufficient structural strength at the elevated temperatures experienced within an operating catalytic converter, may be used as desired. A test of the present pre-catalytic converter and catalytic converter combination 10 was performed on August 12, 1997, to measure the exhaust emissions from an engine E to which the present converter combination 10 was connected. The test was performed on an automobile (1992 Marocco) using an engine from a 1992 Chevrolet Corvette, with the engine meeting the emissions regulations for that model year. The test configuration was somewhat along the lines of the assembly shown schematically in Figure 5, with the present pre-catalytic converter and catalytic converter combination 10 being connected to the exhaust system of an engine E, immediately adjacent or in close proximity to the engine E in order to reduce exhaust temperature losses as much as possible.

A muffler M was installed at the downstream end of the system. While a conventional exhaust resonator R and catalytic converter C are shown in Figure 5, it should be noted that these two components are not necessarily required with the present pre-catalytic converter and catalytic converter combination 10, but may be installed therewith if so desired or required. While the resonator R may be desirable for further noise reduction, it should be noted that the combination of the present pre-catalytic converter and atalytic converter 10, with either a resonator R or muffler M, may obviate any need for further noise reduction means. Similarly, the present pre-catalytic converter and catalytic converter combination 10 serves to preclude any further requirement for further exhaust emissions controls downstream thereof. Results of the test are provided in Table I, following.

TABLE I. EXHAUST EMISSIONS TEST RESULTS

TOTAL CARBON OXIDES OF

NON-METHANE

HYDROCARBONS MONOXIDE NITROGEN HYDROCARBONS

1992 CALIF. 0.41 3.40 1.00

(Not tested AIR RESOURCES in 1992) BOARD STANDARDS

(grams/mile)

LOW EMISSIONS 0.41 3.40 0.20

0.075 VEHICLE

ULTRA LOW 0.41 1.70 0.20

0.040 EMISSIONS VEHICLE

1992 CORVETTE 0.33 1.82 0.63

(Not tested

(90 seconds to in 1992) closed loop)

1992 MAROCCO, 0.08 0.5! 0.63

0.069 PRE-CATALYTIC AND CATALYTIC CONVERTER (240 seconds to closed loop)

It should be noted that the 1992 Marocco is an exotic, high performance automobile which uses the engine and drivetrain components from a 1992 Chevrolet Corvette, including the six speed manual transmission of that drivetrain. This transmission includes a "skip shift" pattern which electronically induces a second gear lockout when the car is shifted from first gear at relatively low throttle openings and engine speed, in order to meet the CAFE (Corporate Average Fuel Economy) requirements without penalty. Thus, the transmission is shifted from first to fourth gear, rather than being sequentially shifted from first to second gear. However, the above noted test results for the 1992 Corvette did not use the skipped shift pattern during the time the engine was not fully warm, but rather used a sequential shift pattern. This enabled the 1992 Corvette to warm up more quickly, requiring only 90 seconds to attain "closed loop" status with the emissions control components being fully heated, to meet the emissions standards as required. The 1992 Marocco utilized the skipped shift pattern, going from first directly to fourth gear, throughout this test. It appears that this caused the engine to warm more slowly, resulting in the electronic controls for the emissions requiring a full 240 seconds to attain "closed loop" status, when the catalytic converter was completely heated. This appears to be the cause for the relatively high oxides of nitrogen emissions component. Further testing is planned in order to check this factor.

Another factor in the above test was an additional catalytic converter component installed on the 1992 Marocco car, comprising a combination catalytic converter and resonator device . An exhaust and emissions system engineer was consulted and found that the present pre-catalytic converter and catalytic converter combination was responsible for about 70 percent of the reduction in emissions of the car. Thus, factoring out the approximately 30 percent emissions reduction due to the catalytic converter and resonator combination installed on the 1992 Marocco, would result in total hydrocarbon and carbon monoxide emissions respectively of 0.11 and 0.71 grams/mile, which still greatly better both the 1992 Corvette emissions test results and the ultra low emissions vehicle standards. Although the test standards did not allow the 1992

Marocco car equipped with the present catalytic converter and pre-catalytic converter combination to be measured by the same standards as the 1992 Corvette, it should be noted that with the exception of the oxides of nitrogen emissions component, the system meets or exceeds the standards for ultra-low emissions vehicles planned for the future. Also, even though the testing of the 1992 Marocco was not conducted to the same standards as that of the 1992 Corvette, the 1992 Marocco equipped with the present pre-catalytic converter and catalytic converter combination, greatly bettered the exhaust emissions measured from the 1992 Corvette for total hydrocarbons and carbon monoxide .

In summary, the present pre-catalytic converter and catalytic converter combination will be seen to result in superior exhaust emissions control for an internal combustion engine. The close proximity of the pre- catalytic converter component to the engine, along with the higher density of catalytically reactive materials at the front of the pre-catalytic converter component, provide significantly higher temperatures in the pre-catalytic converter component for greater reactive efficiency. The higher heat is transmitted to the closely adjacent catalytic converter component, where this additional heat results in further catalytically reactive efficiencies and reductions in exhaust emissions.

The use of a strong and durable material which is capable of withstanding extremely high temperatures, enables the substrates of the present pre-catalytic and catalytic converter components to be constructed to have thinner walls, and thus larger passages therethrough, to reduce restrictions to the flow of exhaust gases through the two components. The relatively thin walls of the substrates, with their relatively high surface area to mass and volume ratios, allow them to heat up more quickly to achieve further gains in catalytic reaction efficiency. The remainder of the structural components of the device, e. g., the canister 12, may be formed of a corrosion resistant steel (i. e., "stainless steel"), for strength and durability. The total effect of the present pre-catalytic converter and catalytic converter combination enables essentially conventional internal combustion engines to meet or exceed the standards set for ultra low emissions vehicles, and will result in a cleaner and healthier environment when motor vehicles are equipped with the system of the present invention.

It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of The following claims.

Claims

1. A pre-catalytic converter and catalytic converter combination, comprising: a canister for installing in close proximity to an internal combustion engine, with said canister including an inlet end, a forward portion adjacent said inlet end, a rearward portion adjacent said forward portion, and an outlet end adjacent said rearward portion; a pre-catalytic converter element installed within said forward portion of said canister, with said pre- catalytic converter element having a foremost portion and a remaining portion; a catalytic converter element installed within said rearward portion of said canister; said pre-catalytic converter element and said catalytic converter element each comprising a substrate having a plurality of longitudinal passages therethrough, with each of said passages being defined by a plurality of substrate walls; and said substrate walls having a coating of catalytically reactive elements, with said foremost portion of said pre-catalytic converter element having a relatively heavier coating of catalytically reactive elements than said remaining portion thereof and said catalytic converter element, for increasing the catalytic reaction and temperature therein.

2. The pre-catalytic converter and catalytic converter combination according to claim 1, wherein said pre-catalytic converter element and said catalytic converter element are in close proximity to one another.

3. The pre-catalytic converter and catalytic converter combination according to claim 1, wherein each of said substrate passages has a large width, for reducing the restriction of exhaust gas flow therethrough .

4. The pre-catalytic converter and catalytic converter combination according to claim 3, wherein said width of each of said substrate passages is substantially greater than .040 inch.

5. The pre-catalytic converter and catalytic converter combination according to claim 1, wherein said walls of each said substrate are thin, for providing a large surface area to substrate volume ratio for accelerating heat transfer to said substrate walls, for correspondingly accelerating the catalytic reaction within said pre-catalytic converter element and said catalytic converter element .

6. The pre-catalytic converter and catalytic converter combination according to claim 1, wherein each said substrate is formed of a ceramic material.

7. The pre-catalytic converter and catalytic converter combination according to claim 6, wherein said ceramic material is Dow-Corning XT.

8. The .pre-catalytic converter and catalytic converter combination according to claim 1, wherein at least said canister is formed of corrosion resistant steel .

9. A pre-catalytic converter and catalytic converter combination, comprising: a canister for installing in close proximity to an internal combustion engine, with said canister including an inlet end, a forward portion adjacent said inlet end, a rearward portion adjacent said forward portion, and an outlet end adjacent said rearward portion; a pre-catalytic converter element installed within said forward portion of said canister, with said pre- catalytic converter element having a foremost portion and a remaining portion; a catalytic converter element installed within said rearward portion of said canister; said pre-catalytic converter element and said catalytic converter element each comprising a substrate having a plurality of longitudinal passages therethrough, with each of said passages being defined by a plurality of substrate walls; and said substrate walls being formed of a ceramic material having a coating of catalytically reactive elements .

10. The pre-catalytic converter and catalytic converter combination according to claim 9, wherein said ceramic material is Dow-Corning XT.

11. The pre-catalytic converter and catalytic converter combination according to claim 9, wherein said foremost portion of said pre-catalytic converter element has a relatively heavier coating of catalytically reactive elements than said remaining portion thereof and said catalytic converter element, for increasing the catalytic reaction and temperature therein.

12. The pre-catalytic converter and catalytic converter combination according to claim 9, wherein said pre-catalytic converter element and said catalytic converter element are in close proximity to one another .

13. The pre-catalytic converter and catalytic converter combination according to claim 9, wherein each of said substrate passages has a large width, for reducing the restriction of exhaust gas flow therethrough.

14. The pre-catalytic converter and catalytic converter combination according to claim 13, wherein said width of each of said substrate passages is substantially greater than .040 inch.

15. The pre-catalytic converter and catalytic converter combination according to claim 9, wherein said walls of each said substrate are thin, for providing a large surface area to substrate volume ratio for accelerating heat transfer to said substrate walls, for correspondingly accelerating the catalytic reaction within said pre-catalytic converter element and said catalytic converter element.

16. The pre-catalytic converter and catalytic converter combination according to claim 9, wherein at least said canister is formed of corrosion resistant steel .