JPH09242530A - Catalytic converter for exhaust emission control for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flow a large quantity of exhaust gas to a peripheral part of a converter in comparison with a central part thereof without providing an exhaust gas guide, which is obstructive, in front of the medium, and to quickly discharge the heat energy, which is applied to a catalyst coat layer, through a metal carrier so as to prevent the early deterioration of the catalyst coat layer, and to satisfactorily maintain the emission control performance of the catalyst for a long time. SOLUTION: In an exhaust emission control catalytic converter 1 for automobile, a catalyst is supported by a metal carrier 14, which is formed by winding a flat heat resistant metal and a waved heat resistant metal in multiple layers and which is formed with multiple cells as a flow passage of the exhaust gas, carrier length in the exhaust gas flow direction at a peripheral part 14A of the winding of the metal carrier 14, which is wound to multiple layers, is formed longer than the carrier length in the exhaust gas flow direction in a central part 14B of the winding, and the central part 14A of the winding is projected than the peripheral part 14B of the winding at the only front side of the exhaust gas flow direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automobile exhaust gas purification using a metal carrier in which a flat plate made of refractory metal and a corrugated plate made of refractory metal are wound in multiple layers to form a large number of cells serving as passages for the flow of exhaust gas. For catalytic converters for automobiles.

[0002]

2. Description of the Related Art A conventional catalytic converter for purifying exhaust gas of an automobile of this type has an inside of a catalyst carrier having a perfect circular cross section or an elliptical cross section (including a racing track cross section having substantially parallel opposing sides). A large number of passages called exhaust gas through which cells flow is provided on the surface of the cell, and fine particles such as alumina are applied to the surface of the cell, on which precious metals such as platinum, palladium and rhodium, and cerium, zirconium, lanthanum, barium, etc. It was made.

[0003] As the catalyst carrier, those made of ceramic materials have been widely used, but in recent years,
Since the cell thickness can be reduced, the ventilation resistance can be reduced, and the thermal conductivity is high, the use of metal carriers having excellent warming characteristics is increasing.

FIG. 6 shows the structure of a conventional catalytic converter for purifying exhaust gas of automobiles using a metal carrier.
Is a metal in which a large number of cells 13 serving as passages for exhaust gas flow are formed by alternately stacking heat-resistant metal flat plates 11 and heat-resistant metal corrugated plates 12 as shown in FIG. The carrier 14 is housed inside the central large-diameter portion of the converter shell 62, and the surface of the cell 13 carries a catalyst.

An exhaust gas purifying catalytic converter using this metal carrier is often used as a carrier for a catalyst, especially a so-called Mani catalyst, which is installed particularly near a manifold. Therefore, the temperature of the catalyst bed may exceed 1000 ° C when the engine load becomes close to that of the engine and is easily exposed to high-temperature exhaust gas, especially when the engine load such as full-open acceleration increases, and the catalyst coat layer is superior. It is necessary to have good thermal durability.

Conventionally, in order to improve the thermal durability of the catalyst coat layer, improvement of the thermal durability of the catalyst itself, that is, suppression of thermal deterioration has been dealt with by improving the catalyst coat layer. However, such improvement may cause problems such as high cost and reduction in activity of the noble metal component due to addition of a new compound.

Therefore, as another method for reducing the thermal deterioration of the catalyst coat layer when the catalyst bed temperature is higher than 1000 ° C., the catalyst coat layer is released by radiating as much heat as possible to the outside of the converter via the carrier. A method of reducing the heat energy received can be considered.

However, it is not easy to cool the catalyst coat layer in the current catalytic converter. For example, when 900 ° C. exhaust gas is constantly introduced into the catalytic converter and the internal temperature is measured, in each cross section of the catalyst, the portion where the temperature is 30 ° C. or more lower than the highest temperature portion in the center of the catalyst is the carrier. Approximately 3 from the outer peripheral surface regardless of type and shape
It is a part up to about 0 mm, that is, a peripheral part.

This is the same whether the catalytic converter is blown with air or water, and it does not change significantly. Also, the temperature at the center of the cross section remains almost unchanged when the converter is cooled from the outside. That is, only the peripheral portion is cold. The reason why the temperature of the portion other than the peripheral portion, that is, the central portion is high is that the heat transfer distance to the outside is large and the amount of the cell wall of the carrier that transfers heat despite the large amount of exhaust gas flowing to the central portion. It is thought that the reason is that the number is small.

As described above, since the exhaust gas flows exclusively in the central part of the carrier, the structure in which the exhaust gas is intentionally difficult to flow in the central part of the carrier in which most of the exhaust gas flows (for example, high cells). As a structure with a high density, a structure with a thick wall thickness, etc.), a method for facilitating the exhaust gas to cool by allowing more exhaust gas to flow to the surrounding area where heat is easily transmitted to the outside, and providing a baffle plate in front of the catalyst A method of changing the distribution of exhaust gas flow is known.

For example, Japanese Patent Laid-Open No. 60-125252: Approximately 1 of the diameter of the converter inlet for loading a honeycomb structure composed of a large number of cells.
The pitch of the cells inside the concentric circle having a diameter of 1.5 to 1.5 is made dense, and the pitch of the cells at the outside is made coarse.

JP-A-62-174525: The pitch of the corrugated plate of the metal carrier and the plate thickness of the flat plate are changed so that the cell density in the central portion is high and the cell density in the peripheral portion is low.

Japanese Unexamined Patent Publication No. 62-228615: An exhaust gas guide which serves as a baffle is provided on the front side of the catalyst to change the distribution of exhaust gas.

[0014]

However, the above-mentioned method may have the following points to be improved.

Since the carrier disclosed in JP-A-60-125252 is a monolithic carrier made of ceramic, it lacks heat dissipation. Further, there is a problem that the purpose cannot be achieved with a carrier having a large cross-sectional area. in addition,
The cell density has an optimum value in terms of catalyst performance, but if the distribution of exhaust gas is changed, the positive effect of improving the distribution may be offset by the negative effect of changing the cell density.

The method disclosed in Japanese Patent Laid-Open No. 62-174525 cannot adopt a method of continuously producing corrugated plates and flat plates having the same shape, resulting in poor productivity and high cost.

In the method disclosed in Japanese Unexamined Patent Publication No. 62-228615, the shape and size of the baffle plate and the mounting structure are likely to be limited by other factors such as the catalyst shape, the engine shape, and the catalyst mounting position. Since the exhaust gas is cooled by the plate itself, when the exhaust gas temperature is 300 ° C. or lower and early activation of the catalyst is required, there is an unfavorable tendency that the temperature further decreases.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a conventional problem, and is a converter for exhaust gas without providing an exhaust gas guide for a baffle plate on the front side of the catalyst. It is possible to flow more to the peripheral portion side of the catalyst coat layer, it is possible to quickly release the thermal energy received by the catalyst coat layer to the outside through the metal carrier, it is possible to prevent early deterioration of the catalyst coat layer due to overheating. Therefore, it is an object of the present invention to provide a catalytic converter for purifying automobile exhaust gas, which is capable of maintaining catalytic performance for a long period of time.

[0019]

As described in claim 1, a catalytic converter for purifying an automobile exhaust gas according to the present invention is characterized in that the carrier carrying the catalyst is made of metal, and the exhaust gas in the central portion of the metallic carrier is exhausted. It is characterized in that the carrier length in the gas flow direction is made stepwise or continuously longer than the carrier length in the peripheral portion.

In an embodiment of the catalytic converter for purifying exhaust gas of an automobile according to the present invention, a second aspect of the present invention is provided.
As described in, the exhaust gas purification of automobiles in which a catalyst is supported on a metal carrier in which a flat plate of a refractory metal and a corrugated plate of a refractory metal are wound in multiple layers to form a large number of cells serving as passages for exhaust gas flow. In the catalytic converter for automobiles, the structure is such that the carrier length in the exhaust gas flow direction in the central part of the winding of the multiple-wound metal carrier is longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding. It is characterized by that.

Also, in the catalytic converter for purifying exhaust gas of an automobile according to the present invention, as described in claim 3, in the exhaust gas flow direction in the central portion of the winding of the metal carrier wound in multiple layers. The carrier length is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding, and the central part of the winding is made to protrude only on the front side in the exhaust gas flow direction from the peripheral part of the winding, Claim 4
As described in, the length of the carrier in the exhaust gas flow direction in the central part of the winding of the metal carrier wound multiple times is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding, The central portion of the winding may be made to protrude from only the rear side in the exhaust gas flow direction with respect to the peripheral portion of the winding, or as described in claim 4, the central portion of the winding of the metal carrier wound multiple times. The length of the carrier in the exhaust gas flow direction in the part is made longer than the length of the carrier in the exhaust gas flow direction in the peripheral part of the winding, and the central part of the winding is only on the rear side in the exhaust gas flow direction from the peripheral part of the winding. Or make it stick out
As described in claim 5, the carrier length in the exhaust gas flow direction at the central portion of the winding of the multiple-wound metal carrier is longer than the carrier length in the exhaust gas flow direction at the peripheral portion of the winding. However, the central portion of the winding may be made to project from both the front side and the rear side of the exhaust gas flow direction from the peripheral portion of the winding. As described above, the support member may be provided between the converter shell and the portion of the central portion of the winding protruding from the peripheral portion of the winding.

Similarly, in the embodiment of the catalytic converter for purifying exhaust gas of automobiles according to the present invention, the invention according to claim 7
The winding shape is a substantially perfect circular shape, or the winding shape is a substantially elliptical shape (lacing having substantially parallel opposing sides). Of course, a track shape is also included.).

Similarly, in an embodiment of the catalytic converter for purifying exhaust gas of an automobile according to the present invention, the method according to claim 9
As described in, the central plate of the winding and /
Alternatively, the plate thickness of the corrugated plate may be made larger than the plate thickness of the peripheral portion of the winding and / or the corrugated plate.
As described in, the cell density of the central part of the winding may be made higher than the cell density of the peripheral part of the winding,
As described in claim 11, the central part of the winding is set to be a part that is located 30 mm or more inside from the outermost peripheral surface of the peripheral part of the winding, or as described in claim 12. In addition, the carrier length in the exhaust gas flow direction in the central part of the winding is within a range of 1.1 times to 2.0 times the carrier length in the exhaust gas flow direction in the peripheral part of the winding, The cross-sectional area of the peripheral portion of the winding is 30% or more of the cross-sectional area of the entire metal carrier 80.
% Or less.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the catalytic converter for purifying automobile exhaust gas according to the present invention, the carrier carrying the catalyst is made of metal, and the carrier length in the exhaust gas flow direction in the central portion of the metal carrier is set. The structure is made longer than the carrier length in the peripheral portion. More specifically, for example, as shown in FIG.
And a corrugated plate 12 made of a heat-resistant metal are wound in multiple layers, and in a catalytic converter for purifying an automobile exhaust gas in which a catalyst is supported on a metal carrier 14 in which a large number of cells 13 are formed as passages for the flow of exhaust gas. The length of the carrier in the exhaust gas flow direction in the central part of the winding of the metal carrier may be made longer than the length of the carrier in the exhaust gas flow direction in the peripheral part of the winding.

In the embodiment, as shown in FIG. 1, the metal carrier 14 installed in the central large-diameter portion of the converter shell 2 of the automobile exhaust gas purifying catalytic converter 1 is wound in multiple layers. Spun metal carrier 1
4, the carrier length in the exhaust gas flow direction in the central portion 14A of the winding 4 is made longer than the carrier length in the exhaust gas flow direction in the peripheral portion 14B of the winding, and the central portion 14A of the winding is wound in the peripheral portion 14B. Further, the structure may be such that only the front side in the exhaust gas flow direction is projected.

Further, in another embodiment, as shown in FIG. 2, in the metal carrier 14 installed in the central large-diameter portion of the converter shell 2 of the catalytic converter 1 for purifying automobile exhaust gas, multiple layers are provided. Rolled metal carrier 1
4, the carrier length in the exhaust gas flow direction in the central portion 14A of the winding 4 is made longer than the carrier length in the exhaust gas flow direction in the peripheral portion 14B of the winding, and the central portion 14A of the winding is wound in the peripheral portion 14B. Further, the structure may be such that it projects only on the rear side in the exhaust gas flow direction.

Further, in another embodiment, FIG.
As shown in FIG. 3, in the metal carrier 14 installed in the central large diameter portion of the converter shell 2 of the catalytic converter 1 for purifying exhaust gas of an automobile, the exhaust gas in the central portion 14A of the winding of the metal carrier 14 wound multiple times. The carrier length in the gas flow direction is made longer than the carrier length in the exhaust gas flow direction in the peripheral portion 14B of the winding, and the central portion 14A of the winding
Can be made to project from both the front side and the rear side in the exhaust gas flow direction from the peripheral portion 14B of the winding.

In the embodiment shown in FIGS. 1 and 2, the winding peripheral portion 14B of the winding central portion 14A is shown in FIGS. 4 and 5, respectively.
The support member 3 may be provided between the more protruding portion and the converter shell 2.

As shown in FIG. 7, the metal carrier 14 has a substantially circular shape, or as shown in FIG. 8, the metal carrier 14 has a substantially elliptical shape (shown in FIG. 8). To be more precise, it may be a racing track shape having parts in which the opposite sides are parallel to each other. In the case of providing the supporting member 3 as shown in FIGS. Also, as shown in FIG. 10, it is also desirable in some cases to provide a plurality of support members 3 at symmetrical positions.

Further, in the embodiment, the plate thickness of the flat plate 11 and / or the corrugated plate 12 of the winding central portion 14A is smaller than that of the flat plate 11 and / or the corrugated plate 12 of the peripheral portion 14B of the winding. The thickness may be increased, the cell density of the winding central portion 14A may be made higher than that of the winding peripheral portion 14B, or the winding central portion 14A may be changed.
Of the carrier in the exhaust gas flow direction in the central portion 14A of the winding is set to 1 mm of the carrier length in the exhaust gas flow direction in the peripheral portion 14B of the winding. It may be in the range of 1 time or more and 2.0 times or less, or the cross sectional area of the peripheral portion 14B of the winding may be in the range of 30% or more and 80% or less of the cross sectional area of the entire metal carrier. it can.

[0031]

The catalytic converter for purifying exhaust gas of an automobile according to the present invention has the above-mentioned structure. By making the length of the cell in the central portion longer than that of the peripheral portion, The ventilation resistance of the part is increased more than that of the peripheral part having a shorter length, and the exhaust gas flows exclusively in the peripheral part having the smaller ventilation resistance.

It is more preferable that the peripheral portion referred to here is a portion that has entered up to 30 mm from the outer peripheral surface of the carrier, and this peripheral portion is a portion that easily transfers heat to the outside. The central portion is a portion inside the peripheral portion. Then, by causing the exhaust gas to flow exclusively in the peripheral portion, the thermal energy received by the catalyst coat layer in the peripheral portion is promptly released to the outside through the metal carrier. Further, in the exhaust gas flowing through the central portion as well, the thermal energy of the maximum 30 mm portion is more likely to be released from the side surface from which the carrier protrudes to the exhaust gas entering the peripheral portion. This heat energy is directly transferred to the converter shell by convection and heat radiation, or transferred from the peripheral portion of the carrier.

In this way, the structure of the automobile exhaust gas purifying converter of the present invention makes it easier to cool the metal carrier, suppresses the deterioration of the catalyst coat layer, and maintains the catalyst performance for a long time. Become.

The extent to which the central portion is made longer than the peripheral portion is more preferably 1.1 to 2.0 times. That is, if it is shorter than 1.1 times, the difference in ventilation resistance between the central portion and the peripheral portion may be canceled by the variation in the catalyst coating amount, and if it is longer than 2.0 times, the thermal shock or vibration that the catalytic converter receives. This is because the central part may vibrate significantly and the connection between the converter shell and the carrier may be broken. Also,
Naturally, the length should fit in the converter.

As described above, the central portion may be popped out either on the side where the exhaust gas enters or on the side where the exhaust gas exits, and it may be set according to the convenience of the vehicle on which it is mounted. . This is because even if a part of the catalyst is advanced, that part comes into contact with the exhaust gas quickly when the exhaust gas temperature is low, warms quickly and is activated early, and the reaction heat heats the entire catalyst to activate it. This is because. Further, the portion protruding and protruding in front is a part of the carrier, so that the heat capacity is small and it is easy to activate faster.

Exhaust gas has a high viscosity when the temperature is high and a large viscosity when the temperature is low. Therefore, when the temperature of the exhaust gas that requires early activation is low, the gas easily flows through the central portion, and the gas does not easily flow through at the high temperature, so deterioration does not pose a problem. The extent to which the air blows out toward the front side may be determined by the maximum temperature of the exhaust gas and the shape of the front diffuser portion of the converter. Of course, the closer the catalyst is to the engine, the higher the exhaust gas temperature is. Therefore, in the case where the temperature is significantly deteriorated, it may be better to place the central part behind.

Of course, the side surface of the protruding portion of the central portion may be connected to the converter shell by a supporting member. This is because the Mani catalytic converter receives vibrations from the outside, so that the protruding central portion shakes and the stress is applied to the joint portion between the carrier and the converter shell. In particular, it is considered necessary in many cases when the central portion is 1.5 times larger than the peripheral portion.

The supporting member used at this time is preferably fixed by welding or brazing. Further, it is necessary that the supporting member does not disturb the distribution of the exhaust gas to a large extent.

When the temperature of the exhaust gas is high, a large amount of the exhaust gas is distributed to the peripheral portion so that heat is easily radiated to the outside. Therefore, the thickness of the flat plate and / or the corrugated plate used in the central portion is smaller than that of the peripheral portion. It may be thicker than the flat plate and / or the corrugated plate, or the cell density of the central portion may be higher than the cell density of the peripheral portion. Any of these means enlarges the difference in ventilation resistance between the central portion and the peripheral portion, and they may be used alone or in combination.

If the exhaust gas is distributed too much in the peripheral portion of the carrier, the conversion rate when the temperature of the exhaust gas is low is adversely affected, so that the cross-sectional area of the peripheral portion occupies 30% of the total cross-sectional area of the carrier. It is desirable to be 80% or less. If it is less than 30%, the cooling effect tends to be small, and if it exceeds 80%, the conversion rate tends to be low at a low exhaust gas temperature, which is not desirable.

The cross-sectional shape of the carrier may be a circle, an ellipse or a racing track, and may be a so-called torus shape (cross section: donut shape) in order to increase the heat radiation area of the converter and increase the heat radiation amount.

The metal carrier is a heat-resistant metal foil plate having a thickness of about 30 μm to 80 μm, for example, Fe-20 wt% C.
A plate made of ferritic stainless steel foil of r-5 weight Al composition is cut out to have a predetermined width, and a part of it is made into a corrugated foil-like corrugated plate, and the flat plate and the corrugated plate are rolled up together. It can be manufactured by laminating a honeycomb body having a large number of cells, inserting the honeycomb body into a heat-resistant stainless steel case (converter shell), and then performing a process such as brazing and joining them. . As a method for producing the carrier of the present invention, a winding method is easy and can be said to be a desirable method, but it is not particularly limited.

In the present invention, the width of the foil-shaped plate is changed between the central portion and the peripheral portion. Therefore, in the manufacturing method in which the foil-shaped plate is rolled up to form a carrier, the width of the foil or plate in the central portion to be rolled up first is increased. , Change the width of the foil or plate to a narrower number with a predetermined number of turns, and decide which part of the center part to be wound (that is, front protrusion, rear protrusion, or both protrusions). It can be manufactured by rolling up.

[0044]

The present invention will be described below with reference to examples.
The present invention is not limited by these.

Example 1 (Step 1) A plate made of a ferritic stainless steel foil having a thickness of 50 μm and containing 20% by weight of Cr and 5% by weight of Al was cut into pieces having a width W ₁ of 118 mm and a W ₂ of 88 mm, and Apply a corrugation process to a part of. This corrugation process is performed so that the density of the cells formed when rolled up is 620 k cells / m ² .

(Process 2) The width W ₁ shown in FIG. ₁ is 118 m.
A stainless steel foil flat plate and a corrugated plate (corresponding to the flat plate 11 and the corrugated plate 12 shown in FIG. 11) are wound up together to have a diameter D ₁ of 88 mm shown in FIG. 1 and a cross sectional shape as shown in FIG. A honeycomb body to be the round central portion 14A is formed.

(Step 3) A flat plate and a corrugated plate (corresponding to the flat plate 11 and the corrugated plate 12 shown in FIG. 11) made of stainless steel foil having a width W ₂ of 88 mm shown in FIG. 1 are provided on the outer periphery of the honeycomb body in the step 2. Both are wound up by the width T ₁ of 30 mm shown in FIG. 1 to make a honeycomb body with a diameter D ₂ of 148 mm shown in FIG. At this time, the width W
₂ One end of the honeycomb body of the central portion 14A to a width _{W 1} of one end of the peripheral portion 14B by winding a foil of 88mm is wound 118mm foil (i.e., rear) Align.

(Step 4) A foil-shaped brazing material (Ni defined in JIS Z-3265) is provided on the outside of the honeycomb body of Step 3.
Wax and Ni-Al as the main component, which is equivalent to BNi-5, is attached to the inside of the casing with a powdered brazing material attached, and then the joining process (as a joining process means,
After heating to 100-600 ° C in air, in vacuum (1
0 to the fourth power Torr) 1180 to 1230 ° C
Heating for 2 hours) to obtain a metal carrier 14 as shown in FIG.

(Step 5) Dinitrodiammine platinum solution was added to 1000 g of activated alumina powder containing γ-alumina as a main component so that the amount of Pt was 1.5% by weight, and after well stirring, an oven was used. Dried at 150 ° C. for 3 hours and baked at 400 ° C. for 4 hours to obtain Pt / Al ₂ O
₃ catalyst powders were obtained. Next, 700 g of this Pt / Al ₂ O ₃ catalyst powder, 300 g of cerium oxide and 1000 g of alumina sol were put into a ball mill pot and pulverized for 8 hours to obtain a slurry. The obtained slurry was applied to a metal carrier, dried and then baked at 400 ° C. for 2 hours. The coating amount at this time was 160 g / L.

Next, a rhodium nitrate solution was added to Rh with 1000 g of activated alumina powder containing γ-alumina as a main component.
The amount was 1% by weight, and the mixture was well stirred, dried in an oven at 150 ° C. for 3 hours, and calcined at 400 ° C. for 4 hours to obtain a Rh / Al ₂ O ₃ catalyst powder. Then
1000 g of this Rh / Al ₂ O ₃ catalyst powder and 1000 g of alumina sol were put into a ball mill pot and pulverized for 8 hours to obtain a slurry. The obtained slurry is already Pt / A
The metal carrier 14 coated with 1 ₂ O ₃ was coated and dried, and then baked at 400 ° C. for 2 hours. At this time, the coating amount of the catalyst was 40 g / L. And the total amount of catalyst applied is 200
A metal-supported catalyst was obtained at g / L.

(Step 6) A catalytic converter 1 of Example 1 was obtained by attaching converter shells 2 serving as diffusers before and after the metal-supported catalyst of step 5. At this time, the protruding side of the central portion 14A was defined as the front side.

[0052] In Example 1, except that the side that protrudes the central portion 14A to the rear side as shown in FIG. 2 to obtain a catalyst converter of Example 2 in the same manner.

Example 3 In Example 1, the width W ₁ is 118 mm and the width of the foil is 15
A catalytic converter of Example 3 was obtained in the same manner except that it was set to 0 mm.

[0054] Example In 4 Example 1, the catalyst of the width _{W 2} is in the same manner in Example except that the dimensions _{T 1} of the FIG. 1 is a honeycomb body of step 3 is wound by an amount which is a 15mm foil of 88mm 4 Got a converter.

Example 5 In Example 1, one end of a foil having a width W ₂ of 88 mm is width W
₁ from the end of the honeycomb body of step 2 of 118 mm foil
A catalytic converter of Example 5 was similarly prepared except that the central portion 14A had a front side protrusion amount of 15 mm and a rear side protrusion amount of 15 mm as shown in FIG. Obtained.

[0056] In Example 6 Example 3 to give the central portion 14A catalytic converters of Examples 6 except in the same manner of attaching the supporting member 3, as shown in FIG.

[0057] In Example 7 Example 1 to obtain a catalytic converter of Example 7 except in the same manner that the width _{W 1} is 930k pieces / ^{m 2} the cell density of the honeycomb body of step 2 made of foil 118 mm.

Example 8 In Example 1, the width W ₁ was 118 mm and the thickness of the foil was 8 mm.
A catalytic converter of Example 8 was obtained in the same manner except that the thickness was 0 μm.

Example 9 In Example 1, the thickness of the foil having a width W ₂ of 88 mm was changed to 30 mm.
A catalytic converter of Example 9 was obtained in the same manner except that the thickness was changed to μm.

Example 10 In Example 1, the width W ₁ was 118 mm and the thickness of the foil was 8 mm.
A catalytic converter of Example 10 was obtained in the same manner except that the foil having a width W ₂ of 88 mm and the thickness of 30 μm was set to 0 μm.

Example 11 In Example 1, the width W ₁ was 118 mm and the thickness of the foil was 8 mm.
A catalytic converter of Example 11 was obtained in the same manner except that the honeycomb body of step 2 had a cell density of 930 k cells / m ² and a foil having a width W ₂ of 88 mm and a foil thickness of 30 μm.

Example 12 In Example 1, the honeycomb body in the step 2 was shaped into a racing track having a major axis of 124 mm and a minor axis of 58 mm, and a foil having a width W ₂ of 88 mm was provided with a width T ₁ of 20 mm. A catalytic converter of Example 12 was obtained in the same manner except that the catalytic converter was wound up along the shape.

Example 13 In Example 12, the honeycomb body in the step 2 was shaped into a racing track having a major axis of 104 mm and a minor axis of 34 mm, and a foil having a width W ₂ of 88 mm and a width T ₁ of 30 mm were used. A catalytic converter of Example 13 was obtained in the same manner except that the catalytic converter was wound up along the shape.

Example 14 In Example 12, the honeycomb body of step 2 had a width W ₂ of 8
Align one end of the 8 mm foil with a position of 15 mm from one end of the honeycomb body of the step 2 of the foil having a width W ₁ of 118 mm (that is, as shown in FIG. 3, the protrusion amount on the front side and the rear side of the central portion 14A is A catalytic converter of Example 14 was obtained in the same manner except that both were set to 15 mm.

[0065]

[Table 1]

[0066]

[Table 2]

[0067] Comparative in Example 1 Example 1, a metallic substrate having a diameter of 118mm and rolled up together a flat sheet and the corrugated sheet width is than foil 155mm, catalytic converter in the same manner in Comparative Example 1 except omitting the step 3 Got

[0068] In Comparative Example 2 Comparative Example 1, a width to obtain a catalyst converter of Comparative Example 2 In the same manner, except that the diameter rolled up together a flat sheet and the corrugated sheet consists of foil 118mm is a metal carrier of 136 mm.

Evaluation Example 1 In the catalytic converters of Examples 1 to 14 of the present invention, room temperature (2
At 5 ° C.) and 300 ° C., air with a flow rate of 2 m ³ / min was flowed, and the amounts of gas flowing through the central portion 14A and the peripheral portion 14B were compared. Table 3 shows the results. In Table 3,
Although the gas flow rates of the central portion 14A and the peripheral portion 14B of each catalyst at room temperature and 300 ° C. are shown, it is clear that the amount of gas flowing through the central portion 14A decreases as the gas temperature increases in any case. That is, at a higher temperature, more gas would flow to the peripheral portion 14B.

[0070]

[Table 3]

Evaluation Example 2 The catalytic converters of Examples 1 to 14 of the present invention and Comparative Examples 1 and 2 were mounted on a hold between 1500 cc engines, the inlet temperature was 950 ° C., and the air-fuel ratio (A /
F) was 14.6 and the gasoline used was a lead-free condition, and a rapid deterioration durability test was conducted.

Then, the purification performance of each catalyst after the durability test was evaluated. At this time, the displacement was 2000
The engine was a cc engine and the air-fuel ratio (A / F) was 14.6, the amplitude of the air-fuel ratio (A / F) was 0.5 A / F, the frequency was 1 Hz, and the inlet gas temperature was 400 ° C. The results are shown in Table 4 below.

[0073]

[Table 4]

As is clear from the results shown in Table 4, in each of the catalytic converters of Examples 1 to 14 of the present invention, deterioration of the catalytic performance was small and excellent purifying performance was obtained even after the durability test. It was recognized that

[0075]

According to the catalytic converter for purifying automobile exhaust gas according to the present invention, as described in claim 1, the carrier for supporting the catalyst is made of metal, and the exhaust gas flow in the central portion of the metal carrier. The carrier length in the direction is longer than the carrier length in the peripheral portion. More specifically, as described in claim 2, a heat-resistant metal flat plate and a heat-resistant metal corrugated plate are wound in multiple layers. In a catalytic converter for automobile exhaust gas purification, in which a catalyst is supported on a metal carrier that has formed a number of cells that form a passage for the flow of exhaust gas when rotated, the exhaust gas flow in the central part of the winding of the metal carrier that is wound multiple times. Since the carrier length in the direction is longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding, more exhaust gas can flow in the peripheral part than in the central part. Since the exhaust gas is easily cooled, it is possible to prevent the catalyst coat layer from being deteriorated by the high-temperature exhaust gas, and therefore it is possible to maintain good purification performance by the catalyst for a long period of time. A significant effect that a catalytic converter for purifying automobile exhaust gas can be provided is brought about.

Then, as described in claim 3,
The length of the carrier in the exhaust gas flow direction in the central part of the winding of the metal carrier wound multiple times is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding, and the center part of the winding is By projecting only the front side in the exhaust gas flow direction from the peripheral part, it is possible to advance part of the catalyst, and when the exhaust gas temperature is low, that part contacts the exhaust gas early. As a result, the effect of early activation by warming the catalyst rapidly and warming of the entire catalyst by the heat of reaction to activate the catalyst early is provided. The length of the carrier in the exhaust gas flow direction in the central part of the wound metal carrier is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding, and the central part of the winding is exhausted from the peripheral part of the winding. Gas flow When the exhaust gas temperature is high such as when the catalyst is brought close to the engine, it is possible to suppress the deterioration of the catalyst by making it protrude only on the rear side of the engine. As described in 5, the length of the carrier in the exhaust gas flow direction in the central part of the winding of the multiple-wound metal carrier is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding, By making the central part of the winding project from the peripheral part of the winding both on the front side and the rear side in the exhaust gas flow direction, early activation of the catalyst can be obtained and high temperature exhaust gas The effect that it becomes possible to prevent early deterioration of the catalyst is brought about.

Further, as described in claim 6,
By providing a support member between the converter shell and the part of the central part of the winding that protrudes from the peripheral part of the winding, it is possible to prevent damage to the central part protruding from the peripheral part. The effect of becoming.

Further, as described in claim 7, the winding shape is a substantially perfect circular shape, and as described in claim 8, the winding shape is a substantially elliptical shape. By doing so, it becomes possible to obtain a catalytic converter for purifying automobile exhaust gas that is easily mounted.

Further, as described in claim 9, the plate thickness of the flat plate and / or the corrugated plate in the central part of the winding is made thicker than the plate thickness of the flat plate and / or the corrugated plate in the peripheral part of the winding. With such a configuration, when the exhaust gas temperature is high, the exhaust gas can be more distributed to the peripheral portion and the heat can be easily dissipated to the outside. The exhaust gas can be distributed more to the peripheral portion by making the cell density of the central portion of the winding higher than that of the peripheral portion of the winding.

Further, as described in claim 11, the central portion of the winding is located at 3 points from the outermost peripheral surface of the peripheral portion of the winding.
By setting the part inside 0 mm or more,
The heat energy received by the catalyst coating layer in the peripheral portion can be promptly released to the outside through the metal carrier, and as described in claim 12, the exhaust gas flow direction in the central portion of the winding can be improved. By setting the carrier length to be 1.1 times or more and 2.0 times or less of the carrier length in the exhaust gas flow direction in the peripheral portion of the winding, it is not affected by the dispersion of the catalyst coating amount, and also the central portion. It is possible to set the difference in ventilation resistance between the peripheral portion and the central portion to a more preferable value without excessive vibration, and as described in claim 13, the cross-sectional area of the peripheral portion of the winding can be set. 30% to 80% of the cross-sectional area of the entire metal carrier
The following effects bring about an effect that the cooling rate is sufficient and the conversion rate at a low exhaust gas temperature can be made favorable.

[Brief description of drawings]

FIG. 1 is an explanation of the inside of a converter shell showing an embodiment of an automobile exhaust gas purifying catalytic converter according to the present invention (an example adopted in Example 1 and the like, in which a central portion 14A projects on the front side). It is a figure.

FIG. 2 is an explanation of the inside of a converter shell showing another embodiment (an example adopted in Example 2 in which the central portion 14A projects at the rear side) of the catalytic converter for purifying automobile exhaust gas according to the present invention. It is a figure.

FIG. 3 shows still another embodiment of an automobile exhaust gas purifying catalytic converter according to the present invention (an example adopted in Example 5 or the like, in which a central portion 14A projects on the front side and the rear side). It is an explanatory view inside a converter shell.

FIG. 4 is still another embodiment of the catalytic converter for purifying automobile exhaust gas according to the present invention (adopted in the sixth embodiment, an example in which the central portion 14A projects on the front side and is supported by the supporting member 3). 2) is an explanatory view of the inside of the converter shell.

FIG. 5 is an explanatory view of the inside of a converter shell showing still another embodiment (an example in which the central portion 14A projects at the rear side and is supported by the support member 3) of the catalytic converter for purifying automobile exhaust gas according to the present invention. .

FIG. 6 is an explanatory view of the inside of the shell of a conventional catalytic converter for purifying exhaust gas from an automobile.

FIG. 7 is an explanatory view showing an example in which the metal carrier has a substantially perfect circular shape.

FIG. 8 is an explanatory view showing an example in which the metal carrier is formed into a substantially racing track shape.

FIG. 9 is an explanatory view showing an example in which the metal carrier is formed into a substantially circular shape and the central portion is supported between the metal shell and the converter shell via a supporting member.

FIG. 10 is an explanatory view showing an example in which the metal carrier is formed into a substantially racing track shape and the central portion is supported between the converter shell and the center portion through a supporting member.

FIG. 11 is a partially enlarged explanatory view of a metal carrier formed by multiply winding a flat plate and a corrugated plate.

[Explanation of symbols]

 1 Automotive Exhaust Gas Purification Catalytic Converter 2 Converter Shell 3 Supporting Member 11 Heat-Resistant Metal Flat Plate 12 Heat-Resistant Metal Corrugated Plate 13 Cell 14 Metal Carrier 14A Metal Carrier Winding Center Part 14B Metal Carrier Winding Peripheral Part

Front Page Continuation (72) Inventor Yasuyuki Murofushi, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Masahiro Takaya, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (13)

[Claims] 1. A catalyst for purifying automobile exhaust gas, characterized in that the carrier carrying the catalyst is made of metal, and the carrier length in the exhaust gas flow direction in the central portion of the metal carrier is longer than the carrier length in the peripheral portion. converter. 2. A catalytic converter for purifying exhaust gas from an automobile, wherein a catalyst is supported on a metal carrier in which a flat plate made of a refractory metal and a corrugated plate made of a refractory metal are wound in multiple layers to form a large number of cells serving as passages for an exhaust gas flow. 2. The automobile exhaust according to claim 1, wherein the length of the carrier in the exhaust gas flow direction in the central portion of the winding of the multiple-wound metal carrier is longer than the length of the carrier in the exhaust gas flow direction in the peripheral portion of the winding. Catalytic converter for gas purification. 3. The length of the carrier in the exhaust gas flow direction in the central part of the winding of the multiple-wound metal carrier is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding,
The catalytic converter for purifying exhaust gas of an automobile according to claim 2, wherein the central portion of the winding is projected only from the front side in the exhaust gas flow direction from the peripheral portion of the winding. 4. The length of the carrier in the exhaust gas flow direction in the central part of the winding of the multiple-wound metal carrier is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding,
The catalytic converter for purifying exhaust gas of an automobile according to claim 2, wherein the central portion of the winding is projected only from the rear side in the exhaust gas flow direction from the peripheral portion of the winding. 5. The carrier length in the exhaust gas flow direction in the central part of the winding of the metal carrier wound in multiple layers is made longer than the carrier length in the exhaust gas flow direction in the peripheral part of the winding,
The catalytic converter for purifying exhaust gas of an automobile according to claim 2, wherein the central portion of the winding is projected from both the front side and the rear side in the exhaust gas flow direction from the peripheral portion of the winding. 6. The catalyst for purifying automobile exhaust gas according to claim 3, wherein a supporting member is provided between the converter shell and a portion of the central portion of the winding protruding from the peripheral portion of the winding. converter. 7. The catalytic converter for purifying exhaust gas from an automobile according to claim 2, wherein the winding shape is a substantially circular shape. 8. The catalytic converter for purifying automobile exhaust gas according to claim 2, wherein the winding shape is substantially elliptical. 9. The plate according to claim 2, wherein the flat plate and / or the corrugated plate in the central part of the winding is thicker than the flat plate and / or the corrugated plate in the peripheral part of the winding. Automotive exhaust gas catalytic converter. 10. The catalytic converter for purifying exhaust gas from automobiles according to claim 2, wherein the cell density of the central portion of the winding is higher than the cell density of the peripheral portion of the winding. 11. The catalytic converter for purifying exhaust gas of an automobile according to claim 2, wherein the central portion of the winding is set to be a portion that is located inside by 30 mm or more from the outermost peripheral surface of the peripheral portion of the winding. 12. The carrier length in the exhaust gas flow direction in the central portion of the winding is 1.1 times or more and 2.0 times or less the carrier length in the exhaust gas flow direction in the peripheral portion of the winding. 11. A catalytic converter for purifying automobile exhaust gas according to any one of 1 to 11. 13. The catalytic converter for purifying exhaust gas from an automobile according to claim 2, wherein the cross-sectional area of the peripheral portion of the winding is 30% or more and 80% or less of the cross-sectional area of the entire metal carrier.