JPH08109823A - Exhaust gas catalyst device - Google Patents

Abstract

PURPOSE: To improve purifying performance, and reduce back pressure low by housing catalyst bodies respectively in catalyst housing parts arranged between an introduction port and an outlet port for exhaust gas of a housing, and thereby reducing independent volumes of the catalysts. CONSTITUTION: In a catalyst device 7, a plurality of catalyst housing parts 8a, 8b are arranged between an introduction port 2 and an outlet port 3 for exhaust gas of a housing 8. Catalysts 9, 10 are housed respectively in the catalyst housing parts 8a, 8b. Exhaust gas from an engine is purified while passing parallelly the catalysts 9, 10 in the catalyst device 7. Purifying performance of whole of the catalyst device 8 is determined based on sum of the volume of the catalysts 9, 10, so that independent volumes of the catalysts 9, 10 can be reduced. It is thus possible to attain both improvement of purifying performance, and reduction of back pressure loss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas catalyst device used in an internal combustion engine such as an automobile engine, and more particularly to a catalyst device capable of achieving a low exhaust pressure loss type and a high exhaust gas purification performance.

[0002]

2. Description of the Related Art As an example of a conventional automobile catalyst device, one shown in FIGS. 5 and 6 is known. Figure 5
6 and 6, (a) is a schematic side view and (b) is a schematic front view. In the catalyst device 1 shown in FIG. 5, a predetermined catalyst substance such as ceramic or metal is used as a material between the inlet 2 for introducing the exhaust fluid and the outlet 3 for discharging the exhaust fluid. It has a catalyst unit 4 made of an elliptic columnar honeycomb structure, and exhaust gas discharged from an engine (not shown) passes through the catalyst unit 4 via an inlet 2 and is discharged from an outlet 3. The exhaust gas is purified by the catalytic action of the single catalyst body 4. The honeycomb-shaped single body 4 is housed in a housing 1a made of a predetermined material such as stainless steel (the hatched portion in the drawing is the single body 4), and the inlets 2 are formed at both ends of the housing 1a. A flange 3a that forms the outlet 2 with the flange 2a is provided. The catalyst device 5 shown in FIG. 6 is different from FIG. 5 in that the shape of the simple substance 6 for the catalyst is a true columnar honeycomb structure, but is the same as FIG. 5 in other respects.

FIG. 7 shows a conventional example in which two catalyst devices 1 or 5 as shown in FIGS. 5 and 6 are used in combination, and a catalyst provided at a position A near an engine (not shown). Since the device 1 or 5 rises in temperature in a short time and exhibits stable purification performance, it is possible to purify high exhaust gas even when the engine is started. On the other hand, by further providing the catalyst device 1 or 5 at the position B away from the engine, at the stage where the temperature rises and the stable purification performance is exhibited, the action of both catalysts further purifies the exhaust gas. It can be done.

[0004]

In the catalyst device 1 shown in FIG. 5, the honeycomb structure of the simple substance 4 for the catalyst has an elliptical cross section, so that the space under the vehicle (under the floor) is limited. It can also be mounted, and it is possible to achieve both exhaust gas purification performance and securing of space, and by increasing the size of the elliptic cylinder honeycomb unit 4 as long as the arrangement space allows, low exhaust pressure loss characteristics and high purification performance can be obtained. It was thought that it could be achieved. However, in actuality, in order for the purification capacity of the catalyst to reach 100%, the temperature of the simple substance 4 is set to 350.
The original performance will not be exhibited unless the temperature reaches ℃ and stabilizes. Therefore, as long as the arrangement space permits, the elliptic cylinder honeycomb unit 4
Although it is possible to make the exhaust pressure loss characteristics low even if the size of the unit 4 can be increased to a certain extent, then the unit 4
However, since the self-heat radiation of the above becomes remarkable, it takes time to reach 350 ° C., and there is a problem that the required purification performance cannot be achieved especially at the time of engine starting.

On the other hand, in the catalyst device 5 shown in FIG. 6, since the true columnar honeycomb simple substance 6 is used, there is a limit to mounting it in a limited space under the vehicle (under the floor).
Since it is not possible to increase the size to a certain level or more, it is difficult to achieve both low exhaust pressure loss characteristics and high purification performance.

Further, in the arrangement and structure of the catalyst device shown in FIG. 7, since the catalyst device is set at the position A close to the engine, it is possible to highly purify the exhaust gas. Since it becomes impossible to achieve low pressure loss, it was impossible to achieve both exhaust pressure low loss characteristics and high purification performance. The present invention has been made in view of the above points, and an object of the present invention is to provide a catalyst device capable of achieving both low exhaust pressure loss characteristics and high purification performance. Further, it is another object of the present invention to provide a structure of a catalyst device capable of enhancing the exhaust pressure low loss characteristic.

[0007]

According to a first aspect of the present invention, there is provided an exhaust gas catalyst device, which comprises a housing in which a plurality of catalyst accommodating portions are set in parallel between an exhaust gas inlet and an outlet. And a plurality of catalyst bodies accommodated in parallel in the catalyst accommodating portion of the housing. According to an embodiment of the present invention, the catalyst body is a honeycomb structure made of a predetermined catalyst substance. According to an embodiment of the present invention, the cross-sectional area of the catalyst body is relatively larger in a portion near the exhaust gas outlet than in a portion near the exhaust gas inlet.

An exhaust gas catalyst device according to another aspect of the present invention is a housing having a catalyst housing portion between an exhaust gas inlet and an outlet, and a catalyst body housed in the catalyst housing portion of the housing. In the exhaust gas catalyst device, the cross-sectional area of at least one of the catalyst body and the catalyst accommodating portion is relatively larger in a portion near the exhaust outlet than in a portion near the exhaust inlet. is there. According to an embodiment of the present invention, the cross-sectional area is gradually increased from a portion near the exhaust inlet to a portion near the exhaust outlet. According to an embodiment of the present invention, the cross-sectional area is gradually increased from a portion near the exhaust introduction port toward a portion near the exhaust outlet.

[0009]

According to the exhaust gas catalyst device according to the first aspect of the present invention, a plurality of catalyst bodies (for example, a single catalyst composed of a honeycomb structure) is provided between the exhaust gas inlet and outlet.
A major feature is that they are provided in parallel. As a result, the exhaust gas discharged from the engine is arranged in a plurality of rows (for example, 2
Since the exhaust gas is purified by passing it in parallel to the catalyst bodies of (rows), the overall purification performance is determined by the total volume of each of the attached catalyst bodies. The individual volumes can be miniaturized, which results in faster activation times of the individual catalyst bodies (time to heat to a given activation temperature, eg 350 ° C.). Therefore, since the catalyst purification efficiency becomes 100% within a short time,
In particular, it can greatly contribute to improving or speeding up the purification performance from the time of engine start.

Further, since the purification performance can be improved, the basis weight of the honeycomb structure of the catalyst body can be roughened, and as a result, the aperture ratio can be increased and the ventilation resistance can be reduced, so that the exhaust pressure can be reduced with low loss. Can be
As a result, the combustion efficiency of the engine can be made high, and at the same time, low fuel consumption and improved power performance can be obtained. As described above, according to the present invention, it becomes possible to secure and promote high purification performance of exhaust gas and smooth exhaust flow, so that both purification performance and low exhaust pressure loss characteristics can be achieved at a high level. It has an excellent effect.

The number of a plurality of catalyst bodies and how to arrange them in parallel are as follows:
Although various selections are possible, if a plurality of rows (for example, two rows) are installed side by side, the overall thickness can be reduced, and it can be mounted in a narrow space because of its space. It has an excellent effect of being suitable for mounting in a limited space on the lower surface (under the floor).

Further, according to another aspect of the present invention, the cross-sectional area of at least one of the catalyst body and the catalyst housing portion is relatively larger in the portion near the exhaust gas outlet than in the portion near the exhaust gas inlet. In this way, the flow of the exhaust fluid flowing in the catalyst body can be made smooth, and the swirl effect can be maintained especially when the exhaust flow rate increases. . That is, when the engine exhaust flow rate increases sharply, the frictional resistance on the wall surface of the exhaust flow path increases, and swirl is generated due to the swirl effect in the flow path (the flow velocity difference / pressure difference between the wall surface side and the center side in the flow path). , The effect of promoting flow)
Is easily broken. However, as in the present invention, if the cross-sectional area of at least one of the catalyst body and the catalyst accommodating portion is set to be relatively larger in the portion near the exhaust outlet port than in the portion near the exhaust inlet port, the exhaust gas flow rate The expansion of the exhaust fluid due to the increase in the exhaust gas will be released by the relative increase in the cross-sectional area near the exhaust outlet, preventing an increase in the frictional resistance near the wall surface and contributing to the continuation of the swirl effect. It has an excellent effect that it can be done. Therefore, even if the engine exhaust flow rate suddenly increases, the exhaust pressure can be reduced to a low loss. It should be noted that the structure of the catalyst body or the catalyst accommodating portion having such a variable cross-sectional area can be applied to a structure in which a plurality of rows of the catalyst bodies are arranged side by side as described above. It can also be applied to a catalyst device including a catalyst body.

[0013]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 1A is a schematic side view of a catalyst device 7 according to an embodiment of the present invention, and FIG. 1B is a schematic front view thereof. In the figure, a catalyst device 7 includes a plurality of catalyst storage parts 8 between an exhaust gas inlet 2 and an outlet 3.
It comprises a housing 8 in which a and 8b are arranged in parallel, and a plurality of catalyst bodies 9 and 10 housed in the catalyst housing portions 8a and 8b, respectively.

The housing 8 is made of a predetermined material such as stainless steel, and is provided with a flange 2a forming an inlet 2 and a flange 3a forming an outlet 3 at both ends of the housing 8. The plurality of catalyst accommodating portions 8a, 8b provided in the housing 8 are, for example, independent cylinders that are separated from each other on their side surfaces, and the inlet 2 (flange 2a) is located near one of the cylinder ends. To the outlet port 3 (flange 3a) in the vicinity of the other end of the cylinder. In each of the catalyst storage portions 8a and 8b, catalyst bodies 9 and 10 having a cylindrical shape as a whole (in the figure, the hatched portions are the catalyst bodies 9 and 10) are stored, respectively. The individual catalyst bodies 9 and 10 themselves are
As is known in the art, the honeycomb structure may be made of a predetermined catalyst material such as ceramic or metal, and may be a structure corresponding to the above-mentioned simple substance of catalyst.

Exhaust gas discharged from the engine is provided in a plurality of rows (two rows in the illustrated example) provided in one catalyst device 7.
Since they are passed through the catalyst bodies 9 and 10 in parallel to be purified, the overall purification performance is determined by the total volume of the adjacent catalyst bodies. Therefore, the individual volumes of the individual catalyst bodies 9 and 10 can be miniaturized. For example, as compared with the conventional case where purification is performed by using only one catalyst, a plurality of catalysts according to the present invention (for example, n
The volume of each one of the catalyst bodies 9 and 10 is about 1 /
could be n. For example, for comparison, two catalyst bodies 9 and 1 according to the present invention shown in FIG.
The relationship between the cross-sectional area of 0 and the cross-sectional area of the conventional one catalyst body 6 is illustrated. The cross-sectional area of the conventional one catalyst body 6 is πR ^2, and each two catalyst bodies 9 according to the present invention,
If each cross-sectional area of 10 is πr ² , for example, πR ² = 2π
Assuming a relationship such as r ² , the radius of each catalyst body 9, 10 according to the present invention is r = R / (√2), and it can be understood that the size is reduced.

As described above, since a plurality of rows of catalyst bodies 9 and 10 are arranged side by side in one catalyst device 7,
Since the volume of each catalyst body 9 and 10 can be reduced, inevitably, self-radiation is small and heating is easy. As a result, the activation time of the individual catalyst bodies 9, 10 (predetermined activation temperature, for example 350 ° C.)
Up to a predetermined temperature (eg 350 ° C.) within an extremely short time at the time of engine start.
C.), the purifying ability can be stabilized within an extremely short time. That is, since the catalyst purification efficiency becomes 100% within a short time, it can greatly contribute to improving or speeding up the purification performance especially from the time of engine start.

In FIG. 2, the catalyst bodies 9 and 10 of the present invention are shown.
Also, a part of the cross section of the honeycomb structure of the conventional catalyst body 6 is schematically shown. As shown in the figure, as compared with the conventional fabric weight 6a of the catalyst body 6 having a honeycomb structure, the catalyst bodies 9, 1 of the present invention are
The unit weight 9a of the honeycomb structure of 0 can be roughened. This is because, as described above, according to the present invention, the purification performance can be improved, and therefore, even if the unit weight 9a of the honeycomb structure of the catalyst bodies 9 and 10 is slightly roughened, the corresponding purification performance can be secured. . Therefore, according to the present invention which can adopt such an embodiment, by relatively roughening the basis weight 9a of the honeycomb structure,
Since the opening ratio of the catalyst bodies 9 and 10 can be increased to reduce the ventilation resistance, the exhaust pressure can be reduced to a low loss, whereby the combustion efficiency of the engine can be made high, and the fuel consumption and the power performance can be reduced. Can be obtained.

FIG. 3 is a diagram showing, for reference, a comparison of purification characteristics, internal combustion engine output characteristics, and exhaust pressure characteristics by the conventional catalyst device and the catalyst device according to the present invention. (A) shows an internal combustion engine output characteristic and exhaust pressure characteristic, (b) shows a purification characteristic. In these characteristic diagrams, the solid line shows the characteristic according to the present invention, and the broken line shows the characteristic according to the conventional device. It can be understood that the present invention is superior to any of the characteristics.

In the above embodiment, the number of the catalyst bodies 9 and 10 is not limited to two rows, but may be larger. In that case, the arrays may be arranged side by side, arranged side by side in the circumferential direction, or any other suitable modified arrangement. In that case, if a plurality of rows are installed side by side, the overall thickness can be made thin, and it becomes possible to mount it in a narrow space and in a narrow space, especially on the lower surface of the vehicle (under the floor).
It is suitable for mounting in the limited space of
It has an excellent effect. Of course, in the case of two rows, since they can be arranged side by side inevitably, the effect of being able to be thin as a whole as described above can be surely obtained.

The plurality of catalyst bodies 9 and 10 do not necessarily have to be arranged right next to each other in parallel, and the exhaust gas introduced from the inlet is branched or shared in parallel for purification. The physical arrangement may be shifted back and forth, which is also an embodiment within the scope of the term “parallel” in the present invention. And Further, in the example of FIG. 1, in the housing 8, the respective catalyst storage portions 8a and 8b have independent cylindrical shapes separated from each other on the side surface,
The present invention is not limited to this, and may have an appropriate shape such as a structure surrounded by a corrugated wall surface, that is, a plurality of catalyst accommodating portions so that a plurality of catalyst bodies 9 and 10 can be arranged in parallel. It suffices that 8a and 8b are set in parallel (side by side or in the circumferential direction).

The shapes of the catalyst bodies 9 and 10 are not limited to the true cylindrical shape as shown in FIG.
It may have an elliptic cylinder shape or another shape. The shapes of the plurality of catalyst bodies 9 and 10 do not necessarily have to be the same shape and the same size, and may be different.

Next, an embodiment of the present invention regarding the shape of the catalyst body will be described with reference to FIG. In FIG. 1, each of the catalyst bodies 9 and 10 has the same cross-sectional area at any position like a true cylinder. However, the catalyst body 9,1
In order to smooth the flow of exhaust gas through zero and maintain the swirl effect, the shape illustrated in FIG. 4 may be used. In each of the examples of FIG. 4, the catalyst bodies 9A, 9
The cross-sectional area of B, 9C and 9D is set to be relatively larger at a portion near the exhaust outlet 3 than at a portion near the exhaust inlet 2. In the example of FIG. 4A, the cross-sectional area of the catalyst body 9A gradually increases from the portion near the exhaust introduction port 2 toward the portion near the exhaust outlet port 3. In the example of (b), the cross-sectional area of the catalyst body 9B gradually increases from the portion near the exhaust introduction port 2 toward the portion near the exhaust outlet port 3.
In the example of (c), the cross-sectional area of the catalyst body 9C continuously changes in the middle portion. In the example of (d), the cross-sectional area of the catalyst body 9D continuously changes in the portion near the exhaust gas inlet 2 and / or the portion near the exhaust gas outlet 3. As a result, the flow of the exhaust fluid flowing in the catalyst bodies 9A to 9D can be made smooth, and the swirl effect can be maintained even when the exhaust flow rate increases. Therefore, even if the engine exhaust flow rate suddenly increases, the exhaust pressure can be reduced to a low loss.

A catalyst body 9A having such a variable cross-sectional area structure
9D can be applied to each of a plurality of rows of catalyst bodies 9 and 10 arranged side by side as in the above embodiment, and of course, a single touch as shown in FIGS. Medium 4, 6
It can also be applied to a catalyst device comprising

By making the catalyst bodies 9A to 9D have a variable cross-sectional area structure as described above, it goes without saying that the internal space cross-sectional area of the catalyst accommodating portion in the housing is necessarily the same cross-sectional area variable structure. . Considering that friction with the wall surface of the exhaust fluid occurs between the exhaust fluid and the wall surface of the catalyst housing portion in the housing, as a modified example of the present invention, the catalyst bodies 9A to 9A are used.
D, 9, 10, 4, 6 itself, not the exhaust space 3
The portion near the exhaust inlet 2 may be relatively larger than the portion near the exhaust introduction port 2. In that case,
Although some gap will be formed around the catalyst body near the exhaust outlet 3, at least the purpose, action, and effect of "maintaining the swirl effect" can be achieved.

In the present invention, the honeycomb structure is not limited to a structure composed of a large number of strict honeycomb-shaped hexagonal structures, but a large number of other appropriate polygonal or circular structures. A structure composed of connections, or a multi-fold curved surface structure such as a stack of a large number of broken cardboards partially illustrated as a schematic cross-sectional view of the honeycomb structure in each of the attached drawings, or a net-like structure The term is meant to include, in short, all multi-area structures (structures containing many area structures in a narrow volume). Further, the present invention is applicable not only to the honeycomb structure type catalyst body but also to other types of catalyst bodies.

[0026]

As described above, according to the present invention, since a plurality of catalyst bodies are provided in parallel between the exhaust gas inlet and outlet, both high purification performance and exhaust pressure low loss characteristics can be obtained. In addition to being effectively realized, it has an excellent effect that the internal combustion engine (engine) can always be operated with high efficiency and fuel saving and power performance improvement can be expected.
Further, since it is possible to reduce the thickness of the catalyst device as a whole, it is possible to mount an efficient and large-capacity catalyst device as a whole in a limited space such as the lower surface of the vehicle.

Further, according to the present invention, the cross-sectional area of at least one of the catalyst body and the catalyst storage portion is made relatively larger in the portion near the exhaust outlet than in the portion near the exhaust inlet. The expansion of the exhaust fluid due to the increase in the exhaust flow rate is escaped due to the relatively large cross-sectional area near the exhaust outlet, preventing an increase in frictional resistance near the wall surface and maintaining the swirl effect. It has an excellent effect that it can contribute. Therefore, even if the engine exhaust gas flow rate suddenly increases, the excellent effect that the exhaust pressure can be made low loss can be obtained.

[Brief description of drawings]

1 is a schematic side view and a schematic front view showing an embodiment of a catalyst device according to the present invention.

FIG. 2 is a schematic cross-sectional view for illustrating the relationship between the cross-sectional area of the catalyst body according to the present invention and the cross-sectional area of a conventional single catalyst body.

FIG. 3 is a diagram showing various characteristics of the catalyst device according to the present invention in comparison with a conventional device.

FIG. 4 is a schematic side view showing another embodiment of the catalyst device according to the present invention.

FIG. 5 is a schematic side view and a schematic front view showing an example of a conventional catalyst device.

FIG. 6 is a schematic side view and a schematic front view showing another example of the conventional catalyst device.

FIG. 7 is a schematic side view showing still another example of the conventional catalyst device.

[Explanation of symbols]

 2 Exhaust gas inlet port 3 Exhaust gas outlet port 7 Catalyst device 8 Housing 8a, 8b Catalyst accommodating portion 9, 10, 9A to 9D Catalyst body

Claims (7)

[Claims] 1. A housing in which a plurality of catalyst accommodating portions are set in parallel between an exhaust gas inlet and an outlet, and a plurality of catalyst bodies accommodated in parallel in the catalyst accommodating portions of the housing. Exhaust gas catalyst device equipped with. 2. The exhaust gas catalyst device according to claim 1, wherein a cross-sectional area of the catalyst body is relatively larger in a portion near an exhaust gas outlet than in a portion near an exhaust gas inlet. 3. The exhaust gas catalyst device according to claim 1, wherein the plurality of catalyst storage portions are arranged side by side. 4. An exhaust gas catalyst device comprising: a housing having a catalyst storage portion between an exhaust gas inlet and an exhaust gas outlet; and a catalyst body accommodated in the catalyst storage portion of the housing. An exhaust gas catalyst device, wherein a cross-sectional area of at least one of the catalyst body and the catalyst housing portion is relatively larger in a portion near an exhaust outlet than in a portion near an exhaust inlet. 5. The exhaust gas catalyst according to claim 2, wherein the cross-sectional area gradually increases from a portion near the exhaust introduction port toward a portion near the exhaust outlet. apparatus. 6. The exhaust gas according to claim 2, wherein the cross-sectional area gradually increases from a portion near the exhaust introduction port toward a portion near the exhaust outlet. Catalytic device. 7. The exhaust gas catalyst device according to claim 1, wherein the catalyst body is a honeycomb structure made of a predetermined catalyst substance.