JP2000097019A - Exhaust gas controlling device for car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promote a uniform exposure of a catalyst substance against an exhaust flow by providing a substrate forming a plurality of parallel flow passages and carried on an active wash coat in an active area of an exhaust gas controlling device and providing a first cell group and a second cell group on these parallel flow passages. SOLUTION: An inlet tube 12 for introducing an exhaust gas from an engine to an active area of an exhaust gas processing device 10 and an outlet area 16 for introducing an exhaust gas processed from a diffuser area 14 and an active area 18 of the exhaust gas control device 10 to a downstream portion of an exhaust system are formed. The active area 18 of the exhaust gas controlling device 10 is provided with a substrate 20 carrying an active wash coat and a plurality of parallel flow passages are provided on the substrate 20. In those parallel flow passages, a first group having the highest density is disposed near a center of the substrate and a second group having a low density is then disposed. Thus, a uniform exposure of a catalyst substance to an exhaust gas stream can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of vehicle exhaust to remove various regulated emissions.

[0002]

BACKGROUND OF THE INVENTION Vehicle emission control regulations are becoming more stringent and vehicle manufacturers have been striving to increase the efficiency of emission control converters. As used herein, “converter” refers to a general oxidation catalyst (conventional oxidation catalyst).
oxidizing catalyst (COC), three-way catalyst (t
hree-way catalyst (TWC for short), NOx traps, thermal reactors or other types of devices with a substantially axial flow path established by an extruded ceramic monolith or other type of structure.

[0003] The inventors of the present invention believe that the flow characteristics through a generally configured ceramic monolith promote efficient operation of the catalyst due to the flow imbalance that occurs in many converters. I don't think there is. For example, about 400 cells per square inch (62 cells / c) shown in FIG.
In the prior art converter shown in FIG. 5 with a uniform cell density of m ² ), an unbalanced flow distribution occurs as shown in FIGS. FIG. 6, which shows a side view of the converter of FIG. 5, shows that the dominant flow is in the lower portion of the substrate, and FIG. 7 shows that the dominant flow is further confined to the outer edge of the substrate, Only a small amount of flow through the center of the carrier is shown. As a result, most of the substrate is only underutilized.
The flows shown in FIGS. 6 and 7 result from the gas being bent 90 degrees as it enters the converter of FIG.

[0004] The result is the same when the converter has a straight-flow system, as shown in FIG. The highest flow velocity is at the center, and the flow velocity decreases toward the side. So, once again, there is an unbalanced distribution of the flow through the converter.

[0005]

SUMMARY OF THE INVENTION In accordance with the present invention, conversion efficiency is enhanced while promoting more uniform exposure of the catalytic material to the exhaust stream, thereby reducing exhaust system back pressure and thereby increasing vehicle performance. There is a need to increase and solve the above-mentioned problems.

[0006]

SUMMARY OF THE INVENTION An exhaust treatment system for a vehicle exhausts exhaust gas processed from an inlet pipe and a diffuser region that guides exhaust gas from an engine to an active region of the exhaust treatment device and the active region of the treatment device. Includes an exit area leading to the downstream portion of the system. The active area has a substrate on which the active washcoat is carried, the substrate having a plurality of parallel flow paths, the flow paths of a first group of cells having a higher density and a second group having a lower density. It has at least a cell group.

[0007] The first group of cells having a higher density is exposed to the exhaust flowing at a relatively high speed, and the second group of cells having a lower density is applied to the exhaust flowing at a relatively low speed. , First and second cell groups are configured.

[0008] The exhaust treatment device according to the present invention may further comprise an active area having a cell-changing substrate having a varying cell density, followed by a second substrate having a constant cell density.

[0009]

According to the exhaust gas treatment apparatus constructed in accordance with the present invention, the exhaust gas flow rate is adapted to the cell density while enabling a low back pressure of the exhaust system. The effect is.

[0010] The exhaust converter constructed according to the present invention comprises:
It is another advantage of the present invention that it can be mounted in smaller volume containers due to the increased efficiency.

[0011] The device constructed according to the present invention can be constructed at low cost with less noble metal loading.
This is still another effect of the present invention.

[0012] Other advantages of the invention, as well as other features and objects, will be apparent to the reader of this specification.

[0013]

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1, an exhaust treatment system according to the present invention has an inlet pipe 12 followed by a diffuser 14. After flowing through the diffuser 14, the exhaust flows through a cell change substrate 20 having a chemically active washcoat carried thereon. The base 20 is
It is shown as having three groups of cells of varying density. As shown more particularly in FIG. 2, the first group having the highest density is located near the center of the substrate 20.
This group, designated 20A, has a density of about 600 cells per square inch (93 cells / cm ² ). What is immediately surrounds the group 20A of 93 cells / cm ² is the group 20B, 62 cells / c
with a density of m ^2. Finally, the rest of the substrate 20, group 20C
Has a density of 31 cells / cm ² .

Substrate 20 is followed by substrate 22, which has an invariant cell structure. It has been determined that the flow through the first substrate 20 straightens and evens out the flow of the substrate 22 so that no cell change structure is required.

The effect of the cell change structure of the substrate 20 is shown in FIGS. As can be seen from these figures, the flow is consequently much more uniform than the flow of the prior art substrate shown in FIGS. In this way, the flow through each portion of the catalyst is more uniform, thus improving exhaust treatment capacity. In addition, the back pressure of the exhaust system may be reduced by allowing the density to be reduced to an extent that acceptable conversion is obtained despite the lower flow resistance.

FIG. 3 shows an example of a cell changeable substrate according to the present invention for use with an exhaust treatment device having no 90 degree bend in the inlet tube as shown in FIG. 93, 62 and 31 cells / c
It should be noted that the area of m ² is much closer around the geometric center of substrate 24.

While the present invention has been shown and described in its preferred embodiments, it will be apparent to those skilled in the art to which the invention pertains that various modifications and alterations may be made without departing from the scope of the invention. It is clear that improvements can be made.

[Brief description of the drawings]

FIG. 1 is a view showing an exhaust treatment apparatus according to the present invention.

FIG. 2 illustrates a cell change monolith substrate according to one of the aspects of the invention.

FIG. 3 illustrates a second cell-changed monolith substrate according to the present invention.

FIG. 4 illustrates a cell-invariant monolith substrate according to the prior art.

FIG. 5 shows a prior art exhaust treatment device having a cell invariant active area.

FIG. 6 is a diagram showing a side view of the flow of the prior art apparatus of FIG. 5;

FIG. 7 is a view showing a plane pattern of the flow in FIG. 6;

FIG. 8 shows a side view of the flow through a prior art device similar to FIG. 5, but having a straight line at the entrance instead of a bend.

FIG. 9 is a diagram showing a plane pattern of the flow in FIG. 8; .

10 is a diagram showing a side view of a flow through the converter configured according to FIG. 1.

11 is a diagram showing a plane pattern of the flow in FIG. 10;

[Explanation of symbols]

 10 Exhaust treatment device 12 Inlet pipe 14 Diffuser 18 Active area 20 Substrates 20a, 20b First cell group 20c Second cell group 22 Second substrate

 ──────────────────────────────────────────────────の Continuing the front page (72) Inventor Seja, Son Lake Forest Drive West, Ann Arbor, Michigan, United States, 4040 (72) Inventor Peter, Re Wendell, West Bloomfield, Michigan, United States, 4290 (72) Inventor Jeon, Yeo, Kim 1170, Doral Court, Troy, Michigan, USA

Claims (13)

[Claims] 1. An inlet pipe and diffuser section for directing exhaust gas from an engine to an active area of an exhaust treatment device, an outlet area for directing exhaust gas treated from the active area of the processor to a downstream portion of an exhaust system, and an active wash. A coat having an active area having a substrate carried thereon, the active area having a plurality of parallel flow paths, the flow paths having a first group of cells having a higher density and a lower density; An automotive exhaust treatment device having at least a second cell group. 2. The exhaust treatment device according to claim 1, wherein the exhaust treatment device has a catalytic converter. 3. The exhaust treatment device according to claim 1, wherein the exhaust treatment device has a thermal reactor. 4. The exhaust treatment device according to claim 1, wherein the exhaust treatment device has a NOx trap. 5. The exhaust system according to claim 1, wherein said first group of cells having a higher density is exposed to exhaust flowing at a relatively high speed, and said second group of cells having a lower density is applied to exhaust flowing at a relatively low speed. The exhaust treatment device according to claim 1, wherein the first and second cell groups are configured to be applied. 6. The base according to claim 1, wherein the base is configured as a cylinder having a substantially circular cross section, wherein high density cells are arranged around a central axis of the base and low density cells are arranged around an edge of the base. Item 2. An exhaust treatment device according to item 1. 7. The base according to claim 1, wherein the base is configured as a cylinder having a substantially elliptical cross section, wherein high density cells are arranged around a central axis of the base, and low density cells are arranged around an edge of the base. Item 2. An exhaust treatment device according to item 1. 8. An inlet tube and a diffuser section for directing exhaust from the engine to an active area of the exhaust treatment device, an outlet section for directing exhaust gas treated from the active area of the processor to a downstream portion of the exhaust system, and a plurality of outlet sections. An active area having parallel flow paths, said flow path having a first group of cells having a density of at least 62 cells / cm ² and a second group of cells having a density of about 31 / cm ² ,
An exhaust treatment system for an automobile, wherein the first group of cells is disposed at a position receiving exhaust flowing at a higher speed, and the second group of cells is disposed at a position receiving exhaust flowing at a lower speed. 9. An exhaust treatment device according to claim 8, wherein said substrate comprises a ceramic monolith. 10. The exhaust treatment device according to claim 8, wherein the substrate comprises an extruded ceramic monolith. 11. An inlet pipe and diffuser section for directing exhaust from the engine to an active area of an exhaust treatment device, an outlet section for directing exhaust gas treated from the active area of the processor to a downstream portion of an exhaust system, and a cell change. A first group of cells having an active area having a substrate, wherein the substrate has a plurality of axially extending parallel channels, the channels having a density of about 93 cells / cm ² , about 62 cells
/ second group of cells with a density of cm ² and has a third group of cells with a density of 31 cells / cm ^2, placed in a position to receive the exhaust gas cells of the first group of flow at a rate higher And a second group of cells and a third group of cells arranged at a position for receiving exhaust gas flowing at a gradually lower speed. 12. The active area further comprises a chemically active washcoat and a second substrate having a constant cell density.
12. The exhaust treatment device according to claim 11, wherein a substrate is disposed downstream of the cell change substrate. 13. The exhaust treatment system according to claim 11, wherein said active area further comprises a chemically active washcoat carried on said substrate.