System and method for low CO emission engine

Abstract

In one aspect, a system is provided and includes an engine including an exhaust valve, an exhaust manifold downstream of the exhaust valve and a muffler downstream of the exhaust manifold. The system also includes a catalyst positioned downstream of the exhaust valve.

Claims

1. A system, comprising: an engine including an exhaust valve, an exhaust manifold downstream of the exhaust valve and a muffler downstream of the exhaust manifold; a catalyst positioned downstream of the exhaust valve; a fuel injector; and a controller connected with the fuel injector, the controller comprising a processor connected to a memory device storing instructions which cause the processor to perform dithering to run the engine rich/lean for a determined period of time; wherein a chamber is disposed upstream of the catalyst, the chamber sized for improved exhaust flow distribution to the catalyst, and a volume of the catalyst is 0.25 to 0.75 of a volume of the chamber.

2. The system of claim 1, wherein the engine is a four-stroke gasoline engine.

3. The system of claim 1, further comprising a portable generator configured to be powered by the engine.

4. The system of claim 3, wherein the portable generator includes a frame at least partially supporting the engine and at least one wheel coupled to the frame.

5. The system of claim 3, wherein the portable generator provides power less than or equal to 10 kilowatts.

6. The system of claim 3, wherein the engine is between 80 cubic-centimeters and 224 cubic centimeters.

7. The system of claim 3, wherein the engine is between 224 cubic-centimeters and 999 cubic centimeters.

8. The system of claim 3, wherein the engine is less than 80 cubic-centimeters.

9. The system of claim 1, wherein the catalyst is positioned in the muffler.

10. The system of claim 9, wherein a cross-section of the muffler is oval shaped.

11. The system of claim 1, further including an oxygen sensor positioned upstream of the catalyst.

12. The system of claim 1, wherein the catalyst is one of a plurality of catalysts.

13. The system of claim 1, wherein the determined period of time is on the order of seconds.

14. The system of claim 1, wherein the instructions cause the processor to perform dithering to run the engine with a dithering frequency of 0.5 Hz to 4 Hz.

15. The system of claim 1, wherein the instructions cause the processor to allow the catalyst to re-oxygenate and control chemical pollutants CO, NOx, and HC present in exhaust from the engine.

16. The system of claim 1, wherein the instructions cause the processor to perform dithering to find a stoichiometric point of the engine.

17. The system of claim 1, wherein the instructions cause the processor to control the rich/lean run of the engine along with the dithering speed and amplitude.

18. The system of claim 1, wherein the muffler comprises double walls.

19. The system of claim 1, further comprising a cylinder head connected to the exhaust manifold and an oxygen sensor positioned upstream of the exhaust manifold in the cylinder head.

20. The system of claim 1, wherein the catalyst and the chamber are both disposed in the muffler.

21. The system of claim 1, wherein an entrance cone is abutted against an entrance of the catalyst to funnel air to the catalyst.

22. The system of claim 21, wherein the entrance cone and the catalyst are both disposed in the muffler.

23. The system of claim 20, wherein an entrance cone is abutted against an entrance of the catalyst to funnel air to the catalyst, the entrance cone disposed in the muffler.

24. The system of claim 1, wherein the catalyst includes a rare earth metal that absorbs oxygen and a wash coat to reduce pollutants including hydrocarbons, carbon monoxide, and nitrogen oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In association with the following detailed description, reference is made to the accompanying drawings, where like numerals in different figures can refer to the same element. The features of the drawings are not necessarily drawn to scale.

(2) FIG. 1 is a schematic of an example engine emission reduction system.

(3) FIG. 2 is a schematic of a side-cutaway view of a portion of the example engine emission reduction system.

(4) FIG. 3 is a schematic of an example muffler capable of being included in the engine emission reduction system.

(5) FIG. 4 is a schematic of an example muffler capable of being included in the engine emission reduction system.

(6) FIG. 5 is a top perspective view of an example device in which the engine emission reduction system may be incorporated.

(7) FIG. 6 is an elevational view of one example of a portion of an engine emission reduction system with examples of catalysts and examples of oxygen sensors positioned in an exhaust manifold.

(8) FIG. 7 is an elevational view of one example of a portion of an engine emission reduction system with examples of catalysts and examples of oxygen sensors positioned in an exhaust manifold

DETAILED DESCRIPTION

(9) While the disclosure may be susceptible to embodiment in different forms, there is shown in the drawings, and herein is described in detail, a specific embodiment with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that as illustrated and described herein. Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity. It is further appreciated that in some embodiments, one or more elements illustrated by way of example in a drawing(s) may be eliminated and/or substituted with alternative elements within the scope of the disclosure.

(10) Referring to FIG. 1, an engine emission reduction system (hereinafter referred to more simply as a “emission reduction system”) 2 in accordance with at least one embodiment includes an engine 4, a muffler 6, electronic fuel injection (EFI) system 8 and/or exhaust manifold 10. In some embodiments, the muffler 6 includes a catalyst 12, but the catalyst 12 can be included in various other positions within the emission reduction system 2, as described in more detail below. The catalyst 12 can also be referred to as a catalytic converter. The engine emission reduction system 2 may be utilized with a large variety of engines 4 and all of such possibilities are intended to be within the spirit and scope of the present disclosure. In some embodiments, the engine 4 can include a small utility internal combustion engine, e.g., about 225 to about 999 cc, capable of being employed in a variety of applications including, for example, a variety of types of power machinery. For example, the engine 4 can include a four-stroke, twin cylinder KOHLER™ CH440 internal combustion engine manufactured by Kohler Company of Kohler, Wis. In some embodiments, the engine 4 may include any number of cylinders including one, twin or more cylinders. Also, in some embodiments, the engine 4 may be air cooled or liquid cooled. Further, in some embodiments, the engine 4 may have a vertical orientation or a horizontal orientation. Although not shown, it will be understood that in some cases the engine 4 can be employed to provide power in chipper/shredders, power washers, edgers, pumps, tillers, pressure washers, aerators, portable generators (e.g., from one to ten KW and/or able to be hand carried or moved by a person), log splitters, dethatchers, tamper/plate compactors, and other small equipment, etc. In some embodiments, it is also possible the emission reduction system 2 of FIG. 1 or other embodiments of emission reduction systems are implemented in conjunction with other types of engines (e.g., other than small utility engines) and/or in conjunction with other types of applications and/or equipment.

(11) In FIG. 1, it is envisioned that the emission reduction system 2 provides a very low carbon-monoxide-emitting, portable gasoline engine, e.g. having one or two cylinders. In some embodiments, other numbers of cylinder engines can use the emission reduction system 2. The emission reduction system 2 can be installed by the engine's manufacturer, however, it is also envisioned that the emission reduction system 2 can be sold as an after-market add-on product capable of being installed by a party other than the engine's manufacturer. Additionally, in at least some of the embodiments, the emission reduction system 2 is implemented in conjunction with the engine 4, the muffler 6 and/or the EFI 8. Nevertheless, the emission reduction system 2 can be used with other types of engine components as well, and need not necessarily be utilized with the engine 4, the muffler 6 and/or the EFI 8.

(12) One example of a device in which the emission reduction system 2 may be used is illustrated in FIG. 5. In this illustrated example, the device is a portable generator 30 and includes a frame 32, at least one wheel 34 coupled to the frame 30 (two wheels 32 in the illustrated example), and at least one handle 36 coupled to the frame 30 (two handles 36 in the illustrated example). In some embodiments, the portable generator 30 may include air cooled. In some embodiments, the portable generator 30 may provide about 10 kilowatts or less of power. In some embodiments, the portable generator 30 may be a Class 1 generator, a Class 2 generator or less than a Class 1 generator. A Class 1 generator may be defined as having an engine size of between about 80 cc (cubic-centimeter) to about 224 cc. A Class 2 generator may be defined as having an engine size of between about 224 cc to about 824 cc or 999 cc. In some embodiments, the portable generator 30 may have an engine size less than 80 cc. It should be understood that the portable generator 30 is only one example of the many types of devices in which the emission reduction system 2 may be utilized. Accordingly, the inclusion of the portable generator is not intended to be limiting upon the present disclosure, but is rather provided to demonstrate at least some of the principles of the present disclosure.

(13) FIG. 2 is a schematic of a side-cutaway view of the example engine emission reduction system 2. In some embodiments, the catalyst 12 is positioned downstream from an exhaust valve 14. Downstream is determined by a flow direction of exhaust in the engine emission reduction system 2. The flow direction is represented by arrow F in FIG. 2. The exhaust valve 14 controls a release of exhaust from the engine 4, through the exhaust manifold 10 connected on one end with an exhaust port 16 and on the other end the muffler 6. In some embodiments, for example in FIGS. 3 and 4, the catalyst 12 is embedded or included in the muffler 6, e.g., a stainless-steel muffler, a low carbon steel, etc. Positioning the catalyst 12 in the muffler 6 may increase a life of the catalyst 12. In embodiments with the catalyst 12 positioned in the muffler 6, the muffler 6 may be made of stainless steel. In some embodiments, for example in FIGS. 6 and 7, the catalyst 12 is positioned in the exhaust manifold 10. For example, the catalyst 12 can be positioned in a can in piping of the manifold 10. Positioning the catalyst 12 in the manifold 10 may result in better performance of the catalyst 12. For example, reactions may still be taking place or a higher quantify of reactions are taking place in the manifold 10 versus further downstream. The catalyst 12 may perform better at reducing emissions in this environment than at positions further downstream. In embodiments with the catalyst 12 positioned in the manifold or locations other than the muffler 6, the muffler 6 may be made of low carbon steel or a different material other than stainless steel. In some embodiments, the catalyst 12 is positioned close to the exhaust valve 14, e.g., within about eight to about twenty-four inches of the exhaust valve 14. In some embodiments, the catalyst 12 is positioned close to the exhaust port 16, e.g., within about eight to about twenty-four inches of the exhaust port 16. In some embodiments, the catalyst 12 is positioned within the exhaust port 16. In a multi-cylinder engine 4, in some embodiments, there may be a catalyst 12 for each cylinder. Positioning the catalyst 12 in these manners relative to exhaust valve 14, exhaust port 16, etc. may be referred to as close coupled. That is, the catalyst 12 is close coupled to the exhaust valve 14, exhaust port 16, etc. Close coupling the catalyst 12 relative to these components of the engine emission reduction system 2 can provide temperature and/or performance advantages. In some embodiments, catalyst 12 may be positioned about 6 inches from the exhaust valve 14. In some embodiments, the catalyst 12 may be positioned between about 4 to 10 inches from the exhaust valve 14. In some embodiments, the catalyst 12 may be positioned between about 1 to about 24 inches. In some embodiments, the catalyst 12 is ceramic. In some embodiments, the catalyst 12 is metallic.

(14) With continued reference to FIG. 2, in some embodiments, one or more oxygen (O2) sensor(s) 18 are positioned in the exhaust manifold 10. The O2 sensor(s) 18 can be positioned a determined distance, e.g., about 0.25 to about ten inches, from the exhaust valve 14. In some embodiments, the O2 sensor may be positioned about six inches from the exhaust valve 14. In some embodiments, the O2 sensor may be positioned about 1 inch form the exhaust valve 14. In some embodiments, the O2 sensor(s) 18 can be positioned a determined distance from the exhaust port 16. In some embodiments, the O2 sensor(s) 18 can be positioned before or upstream of the catalyst 12 with regard to a direction of the exhaust. In some embodiments, the O2 sensor(s) 18 may be positioned between the catalyst 12 and the exhaust valve 14. In some embodiments, the O2 sensor(s) 18 can be positioned before or upstream of the exhaust manifold 10, e.g., in the cylinder head 20.

(15) In some embodiments, the engine 4 may include multiple cylinders. In such embodiments, the engine emission reduction system 2 may include a separate catalyst 12 and separate O2 sensor 18 for each cylinder of the engine 4. For example, with reference to FIGS. 6 and 7, the engine emission reduction system 2 includes a catalyst 12 and an O2 sensor 18 for each cylinder (two cylinders in the illustrated examples).

(16) A transport distance of the fuel injector 8 to the O2 sensor 18 can affect an A:F dithering speed of the fuel into the exhaust stream. In some embodiments, minimizing or reducing the transport distance may speed-up the feedback of the system.

(17) In some embodiments, the catalyst 12 may include a rare earth metal that absorbs O2 and wash coat to reduce pollutants including hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxide (NOx). Many types of catalyst 12 can best reduce HC and CO when the engine 4 is run lean of stoichiometric (e.g., 14.7:1), e.g., about 15:1 lean. However, in some of these systems, NOx may be best reduced when the engine 4 runs rich, e.g., about 13.9:1 rich. With intentional dithering, the fuel injector 8 can be calibrated to run the engine 4 rich/lean/rich/lean for a determined amount of time, e.g., on the order of seconds. In some embodiments, a dithering frequency may be about 0.5 to about 4 Hz. The dithering can allow the catalyst 12 to re-oxygenate and best control the three main chemical pollutants, CO, NOx and HC, present in the exhaust. Additionally or alternatively, the dithering can be used to find a stoichiometric point of the engine 4.

(18) A controller connected integrated with the fuel injector 8, and/or operably connected with the fuel injector 8, can control the rich/lean, etc. dithering speed and amplitude. The controller can include one or more processors and one or more memory devices. The memory can include one or more of a program memory, a cache, random access memory (RAM), a read only memory (ROM), a flash memory, a hard drive, etc., and/or other types of memory. In some embodiments, the memory can store instructions (e.g., compiled executable program instructions, uncompiled program code, some combination thereof, or the like)), which when performed (e.g., executed, translated, interpreted, and/or the like) by the processor, causes the processor to perform the dithering and any other processes described herein.

(19) FIGS. 3-4 are schematics of example implementations of the muffler 6. The muffler 6 can include double walls 20, e.g., to improve heat related performance of the catalyst 12 and noise performance of the muffler 6. A chamber 22 in front of the catalyst 12 can be sized for better exhaust flow distribution to the catalyst 12. In some embodiments, a catalyst volume is about 0.25 to about 0.75 of a volume of the chamber 22. In some embodiments, the surface area and air flow through the catalyst 12 can be optimized with a determined geometry of the interior of the muffler 6, e.g., by making one of the muffler partitions into a catalyst entrance cone 24, e.g., to funnel air to the catalyst 12. The shape of the entrance cone 24 can assist with maximizing an amount of surface area of the catalyst 12 impacted by the exhaust. In some embodiments, a cross section of the muffler 6 with a catalyst 12 is shaped like an oval (race-track). In other embodiments, other shapes can be used such as, for example, circular, polygonal perimetered shapes, arcuately perimetered shapes, or a combination of polygonal and arcuately perimetered shapes.

(20) While particular embodiments are illustrated in and described with respect to the drawings, it is envisioned that those skilled in the art may devise various modifications without departing from the spirit and scope of the appended claims. It will therefore be appreciated that the scope of the disclosure and the appended claims is not limited to the specific embodiments illustrated in and discussed with respect to the drawings and that modifications and other embodiments are intended to be included within the scope of the disclosure and appended drawings. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it is appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the disclosure and the appended claims.

(21) Many modifications and other embodiments set forth herein will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.