JPH1061431A - Catalyst converter for vehicle exhaust system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize diffusers without increasing a ventilation resistant value, and improve vehicle mounting property in a catalytic converter in which the diffusers in which enlarged parts are formed, are mounted on the exhaust gas inflow side and the exhaust gas outflow side of an outer cylinder, by forming the enlarged parts of the diffusers into an involute curve shape. SOLUTION: A catalytic converter 17 purifying the exhaust gas of an engine is formed in a manner that a ceramic catalytic support is mounted through a retaining member and a foamable seal member in a pair of half split outer cylinders 3 in which diffusers 11, 12 are integrally formed at both ends. The diffusers 11, 12 are mounted for the purpose of lowering exhaust gas rectification and the ventilation resistance of the catalytic converter 17, however, the whole length of respective diffusers 11, 12 is shortened to, for example 2/3, in comparison with the conventional case, and also enlarged parts 11a, 12a between exhaust pipe connecting parts 13, 14 and outer cylinder connecting parts 15, 16 are gradually enlarged and formed into an involute curve. Hereby, an exhaust gas G flow can be smoothened, and the ventilation resistant value of the catalytic converter 17 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalytic converter mounted on a vehicle exhaust system.

[0002]

2. Description of the Related Art Generally, a vehicle exhaust system is provided with a catalytic converter for purifying exhaust gas discharged from an engine.
2. Description of the Related Art Conventionally, a ceramic catalyst carrier formed of ceramics as disclosed in Japanese Utility Model Laid-Open No. 4-52525 and a metal catalyst carrier in which a thin metal corrugated plate and a flat plate are multiplexed are widely known.

[0003] After the catalyst carrier is subjected to a noble metal catalyst loading treatment, in the case of a ceramic catalytic converter, as disclosed in the above-mentioned publication, a pair of half-split outer cylinders in which diffusers are integrally formed at both ends are provided. Inside, a ceramic catalyst carrier is mounted via a holding member or a foamable sealing member (interram mat). In a metal catalyst converter, as shown in FIG. After being inserted into the outer cylinder 3, the diffuser 5 is joined to the exhaust gas inflow side (upstream side) and the exhaust gas outflow side (downstream side) of the outer cylinder 3, respectively, to form the metal catalytic converter 7.

The diffuser 5 is mounted for the purpose of rectifying exhaust gas from an exhaust pipe (not shown) and reducing the ventilation resistance of the catalytic converter 7, and as shown in FIG. Diffuser 5 to be attached to
The expansion portion 5c which gradually expands from the exhaust pipe connection portion 5a formed along the outer shape of the exhaust pipe to the outer cylinder connection portion 5b formed along the outer shape of the outer cylinder 3 has a tapered shape. It is molded into. A diffuser 5 having the same shape as the diffuser 5 is mounted on the outer periphery of the outer cylinder 3 on the exhaust gas outflow side.

[0005]

However, in recent years, downsizing of the catalytic converter has been desired due to space restrictions under the floor of the vehicle and demands for weight reduction of the vehicle. Therefore, it is clear that simply reducing the size of the diffuser 5 will deteriorate the ventilation resistance, and a compact catalytic converter with good vehicle mountability while maintaining at least the same ventilation resistance as the conventional one is desired. It had been.

The present invention has been devised in view of the above-mentioned circumstances, and a catalyst for a vehicle exhaust system in which the size is reduced and the mountability of the vehicle is improved without increasing the airflow resistance value as compared with the related art. It is intended to provide a converter.

[0007]

In order to achieve the above object, a catalytic converter for a vehicle exhaust system according to a first aspect of the present invention is provided with an expanding portion that gradually expands from an exhaust pipe connecting portion to an outer cylinder connecting portion. In the vehicle exhaust system catalytic converter with the diffuser mounted on the exhaust gas inflow side and exhaust gas outflow side of the outer cylinder, the expanded part of the diffuser on the exhaust gas inflow side is formed with an involute curve shape. And

[0008] The invention according to claim 2 is based on claim 1.
In the catalytic converter of the vehicle exhaust system described above, the expanded portion of the diffuser on the exhaust gas outflow side is formed with an involute curve shape, and the invention according to claim 3 is the invention according to claim 1. In a catalytic converter of a vehicle exhaust system, an expanded portion of a diffuser on an exhaust gas outflow side is formed in a tapered shape.

(Function) Purification of exhaust gas is achieved by mounting the catalytic converter according to each claim in a vehicle exhaust system. Exhaust gas flowing into the diffuser from an exhaust pipe is expanded into an involute curve. The catalyst carrier is uniformly guided to the upstream end of the catalyst carrier while spreading smoothly along the portion.

In the catalytic converter according to the second and third aspects, the exhaust gas passing through the catalyst carrier is smoothly guided to the downstream exhaust pipe along the inner wall of the diffuser on the exhaust gas outflow side. .

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same components as those in the conventional example shown in FIG. 5 are denoted by the same reference numerals.

FIG. 1 shows an embodiment of the catalytic converter according to the first and second aspects of the present invention. The inner diameter M of the exhaust pipe connecting portions 13 and 14 formed along the outer shape of the exhaust pipe is 50.8 mm and the outer pipe 3 is formed along the outer shape of the outer cylinder 3 as shown in FIG. The inner diameter N of the outer cylinder connecting portions 15 and 16 is 108φ.
mm, these are the diffusers 5 shown in FIG.
It has the same dimensions as.

The length L ₁ in the front-rear direction of the diffuser 5 shown in FIG. 5 is 217 mm in the related art, whereas the catalytic converter 17 according to the present embodiment is different from the diffuser 1 in FIG.
The 1,12 molded drives out the diffuser 5 and the same material, and the total length thereof in the longitudinal direction of the length L ₂ as 150mm as well as reduced to 2/3 compared to the conventional, instead of the conventional tapered The expansion portions 11a and 12a between the exhaust pipe connection portions 13 and 14 and the outer cylinder connection portions 15 and 16 are formed by gradually expanding with involute curves, respectively.

Thus, as described above, the diffusers 11, 1
In forming the two expanded portions 11a and 12a with an involute curve, the inventor of the present invention uses the catalytic converter 17 of FIG. 1 equipped with the diffusers 11 and 12 of FIG. 3 and 4, the diffuser 19,
A ventilation resistance experiment was performed using a catalytic converter equipped with each of No. 21.

The diffusers 19 and 21 are made of the same material as the diffusers 11 and 12, each having a length L ₂ in the front-rear direction, an inner diameter M of the exhaust pipe connecting portions 23 and 25, and an outer cylinder connecting portion 27. , And 29 have the same dimensions as the diffusers 11 and 12, respectively, and the diffuser 19 of FIG. 3 has a tapered expansion portion 31 between the exhaust pipe connection portion 23 and the outer cylinder connection portion 27. The diffuser 21 shown in FIG. 4 is formed by connecting the exhaust pipe connecting portion 25 and the outer cylinder connecting portion 29 with a sin curve to form the expanded portion 33. In the experiment, these are separated for each shape. A catalytic converter was formed by joining the cylinder 3 to the exhaust gas inflow side and the exhaust gas outflow side, respectively.

The number of cells of the metal catalyst carrier 1 is 200 per square inch. Then, as shown in FIG.
³ / in the range of Min～10m ³ / min by flowing of exhaust gases G in the catalytic converter 17 to measure the differential pressure of the metal catalyst carrier 1 for each flow rate. The experimental results (measured airflow resistance data) are shown in Table 1 below.
, The “taper” is a catalytic converter using the diffuser 19 in FIG. 3, the “sin curve” is a catalytic converter using the diffuser 21 in FIG. 4, and the “involute” is the catalyst shown in FIG. The converter 17 is shown, and the unit of the experimental result is mmAq.

[Table 1] As is apparent from the above experimental results, when the diffusers 19 and 21 shown in FIGS. 3 and 4 are used, the overall length of the catalytic converter is shorter than that of the conventional one, but about 9% of the ventilation is reduced. Although it is not preferable because the resistance value is deteriorated as compared with the conventional case, the diffusers 11 and 12 shown in FIG.
In the catalytic converter 17 shown in FIG. 1 using the above, the airflow resistance value is improved by about 8% as compared with the related art.

In this embodiment, based on the above experimental results, an involute curve shape is selected as the shape of the expanded portions 11a, 12a of the diffusers 11, 12.
Exhaust gas can be purified by mounting the catalytic converter 17 using such diffusers 11 and 12 in the vehicle exhaust system. However, the exhaust gas G flowing into the diffuser 11 from the exhaust pipe is expanded into an involute curve. Opening 1
1a, is uniformly guided to the upstream end of the metal catalyst carrier 1 while spreading smoothly along the metal catalyst carrier 1;
Exhaust gas G passing through the exhaust gas diffuser 1
2 is smoothly guided along the inner wall to the exhaust pipe on the downstream side.

According to the present embodiment, since the exhaust gas G is uniformly guided to the upstream end of the metal catalyst carrier 1, the catalytic converter shown in FIG. 7, the flow of the exhaust gas G becomes smoother, and the ventilation resistance value of the catalytic converter 17 is improved.
The overall length of the catalytic converter 17 has been shortened by about 134 mm, and the mountability on the vehicle has been improved.

Although not shown, the diffuser 11 is used on the exhaust gas inflow side and the diffuser 19 having a tapered expansion portion is used on the exhaust gas outflow side, as in one embodiment of the invention according to claim 3. In this case (F inbo, R taper in Table 1), as shown in Table 1, the ventilation resistance value is further 2%.
According to such an embodiment, the intended purpose can be further achieved.

In each of the above embodiments, the present invention is applied to a metal catalytic converter, but it goes without saying that the present invention can be applied to a ceramic catalytic converter. or,
In the above embodiments, the outer cylinder 3 on which the metal catalyst carrier 1 is mounted
When the metal catalyst carrier and the outer cylinder on which the metal catalyst carrier is mounted have a so-called substantially track-shaped cross section, for example, the short axis radial direction and the long axis radial direction of the expanded portion of the diffuser mounted thereon May be formed with an involute curve shape.

[0021]

As described above, according to the catalytic converter of the present invention, the size can be reduced as compared with the prior art, and the mountability on the vehicle can be improved. Nothing to do.

[Brief description of the drawings]

FIG. 1 is a side view of a catalytic converter according to an embodiment of the present invention.

FIG. 2 is a side view of a diffuser formed with an involute curve shape.

FIG. 3 is a side view of a diffuser formed in a tapered shape shorter than a conventional one.

FIG. 4 is a side view of a diffuser formed with a sin curve.

FIG. 5 is a side view of a conventional catalytic converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal catalyst carrier 3 Outer cylinder 11, 12, 19, 21 Diffuser 11a, 12a Expanding part 17 Catalytic converter

Claims (3)

[Claims] An expanding portion (11a, 1) that gradually expands from an exhaust pipe connecting portion (13, 14) to an outer cylinder connecting portion (15, 16).
In the catalytic converter of the vehicle exhaust system in which the diffusers (11, 12) formed with 2a) are mounted on the exhaust gas inlet side and the exhaust gas outlet side of the outer cylinder (3), the diffuser (11) on the exhaust gas inlet side is expanded. Open (11
A catalytic converter for a vehicle exhaust system, wherein a) is formed with an involute curve shape. 2. A catalytic converter for a vehicle exhaust system according to claim 1, wherein the expanded portion (12a) of the diffuser (12) on the exhaust gas outflow side is formed with an involute curve shape. 3. The catalytic converter of a vehicle exhaust system according to claim 1, wherein the expanded portion of the diffuser on the exhaust gas outflow side is formed in a tapered shape.