JPH09242533A - Catalytic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalytic converter, in which a thermal expansion mat is easily pressed for charge in comparison with the conventional one and a ceramics carrier having the circular cross section or elliptical cross section can be easily inserted into an outer cylinder at the time of housing the ceramics carrier, which is formed by winding the thermal expansion mat, in the outer cylinder at the time of manufacture. SOLUTION: This catalytic converter is formed of a taper-shaped outer cylinder 1 having a small diameter over from a front part to a rear part thereof, a ceramics carrier 13 held through a thermal expansion mat 11 pressed into the outer cylinder 1, an outer shell 3 fitted to a front part of the outer cylinder 1, an inner shell 15, of which front end is fixed to the inner circumference of a front side of the outer shell 3 and which is formed with an annular flange part 17, which abuts on the front end of the thermal expansion mat 11 so as to push it to the axial direction of the ceramics carrier 13, in the circumferential edge of a rear side thereof, and a diffuser 9 fitted to a rear part of the outer cylinder 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a catalytic converter mounted in a vehicle exhaust system or the like.

[0002]

2. Description of the Related Art Conventionally, for example, in a vehicle exhaust system, a catalytic converter for purifying exhaust gas discharged from an engine is installed under the floor. Recently, however, in addition to such a catalytic converter, Japanese Utility Model Laid-Open No. 5-12622 has been disclosed. A manifold converter as disclosed in U.S.A. is attached to an exhaust manifold of an engine.

Conventionally, a ceramic carrier has been widely used as a catalyst carrier used in this type of catalytic converter, and in order to manufacture a catalytic converter using such a ceramic carrier, a supporting treatment of a noble metal catalyst is carried out on the ceramic carrier. After applying it, a method such as winding a heat-expandable mat (interram mat) around the outer circumference and storing them in a pair of half-split containers, or press-fitting into a casting container using hydraulic pressure is adopted. Has been.

[0004]

By the way, in the conventional method of press-fitting the ceramics carrier around which the heat-expandable mat is wound as described above into the container, the ceramics carrier having an elliptical cross-section can be pressed vertically and horizontally. Because positioning is difficult,
The reality is that only ceramic carriers having a circular cross section are used.

However, when a manifold converter having a large capacity is connected to, for example, an exhaust manifold, a ceramic carrier having a circular cross section has a large diameter, which makes it difficult to mount due to the layout of a radiator or an engine. When mounted under the floor, it is not possible to use a ceramic carrier with a large diameter circular cross section due to the minimum ground clearance, or due to the layout with other equipment, a ceramic carrier with a large diameter circular cross section. There was a problem such as the inability to install a catalytic converter using

Further, because of the structure of holding the ceramic carrier by the heat-expandable mat, if the packing density of the heat-expandable mat is not sufficient, the heat-expandable mat scatters due to pulsation of exhaust gas and the carrier holding force cannot be maintained. There is a risk that the ceramics carrier may hit the container and be damaged by long-term use. Therefore, conventionally, when a ceramics carrier wound with a heat-expandable mat is press-fitted into a container, the heat-expandable mat with a high density of 1 g / cc is press-fitted and filled into the container together with the ceramics carrier. The size of the tool is large,
There was a drawback that it took a lot of time for press-fitting work.

On the other hand, in a method of winding a heat-expandable mat around the outer periphery of a ceramics carrier and storing them in a half-split container such as a pair of upper shells and lower shells, a ceramics carrier having an elliptical cross section is used. On the other hand, there is a problem that the ceramics carrier is sufficiently pressed in the minor axis direction (vertical direction) by the upper shell and the lower shell, but not in the major axis direction (horizontal direction).

The present invention has been devised in view of the above circumstances, and when the ceramics carrier around which the thermally expandable mat is wound is housed in the outer cylinder (container) at the time of manufacture, the thermal expansion is easier than in the conventional case. It is an object of the present invention to provide a catalytic converter capable of press-fitting and filling a flexible mat and easily inserting not only a ceramic carrier having a circular cross section but also a ceramic carrier having an elliptical cross section into an outer cylinder.

[0009]

In order to achieve such an object, a catalytic converter according to a first aspect of the present invention includes a taper-shaped outer cylinder having a diameter gradually decreasing from a front portion to a rear portion, and an outer cylinder. A ceramic carrier held in the outer cylinder through a press-fitted and filled thermal expansion mat, an outer shell attached to the front portion of the outer cylinder, and the ceramic carrier mounted coaxially with the front end portion. Is fixed to the front inner circumference of the outer shell, and an annular flange portion is formed on the rear peripheral edge portion, which abuts on the front end portion of the thermally expandable mat and presses it in the axial direction of the ceramics carrier. It is characterized by comprising an inner shell and a diffuser attached to the rear portion of the outer cylinder.

(Function) According to the catalytic converter of the first aspect, the inner shell that has been thermally expanded axially presses the thermally expandable mat with the inflow of exhaust gas, and the thermal expansion of the outer cylinder due to the thermal expansion. Prevents a decrease in the packing density of the mat, and
The inner shell guides the exhaust gas directly to the ceramic carrier, and prevents the exhaust gas from hitting the front end portion of the thermally expandable mat.

In the catalytic converter according to the first aspect of the present invention, since the outer cylinder is formed in a tapered shape, it can be easily inserted into the outer cylinder in manufacturing even if the ceramic carrier has an elliptical cross section. In addition, the outer cylinder is formed in a tapered shape, and only the heat-expandable mat needs to be press-fitted. Therefore, the heat-expandable mat is press-fitted and filled in the outer cylinder with a force smaller than the conventional force. Will be done.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of a catalytic converter according to claim 1, wherein 1 is a metal having an elliptical cross-section formed in a tapered shape in which the diameter is gradually reduced from the front part to the rear part (for example, With an outer cylinder made of stainless steel,
On the outer periphery of the front part, there is a substantially bowl-shaped outer shell 3 having a front flange 5 welded to the exhaust gas inlet 3a,
A tapered diffuser 9 having a rear flange 7 welded to an exhaust gas outlet 9a is welded to the outer periphery of the outer cylinder 1 coaxially with the outer cylinder 1.

A ceramic carrier 13 having an elliptical cross-section having a thermally expandable mat 11 wound around the outer cylinder 1 is housed in the outer cylinder 1. The thermally expandable mat 11 is press-fitted and filled to a predetermined density. Thus, the ceramic carrier 13 is held coaxially with the outer cylinder 1. In the figure, 15 is an inner shell mounted in the outer shell 5. The inner shell 15 is mounted coaxially with the ceramics carrier 13, and the front end of the inner shell 15 is inside the exhaust gas inlet 3a of the outer shell 3. It is welded around. The inner shell 15 is extended to the front end of the ceramics carrier 13, and the front end of the ceramics carrier 13 is loosely inserted in the rear end thereof. An annular flange portion 17 is formed on the rear peripheral portion of the inner shell 15 so as to be in pressure contact with the front end portion of the heat-expandable mat 11. The density of the mat 11 is maintained by the pressing force of the inner shell 15.

Exhaust gas G is higher than that of the outer shell 5.
The inner shell 15 that is exposed to
When the exhaust gas G flows in through the inner shell 15, the inner shell 15 that thermally expands in the axial direction pressurizes the thermally expandable mat 11, and the packing density of the thermally expandable mat 11 decreases due to the thermal expansion of the outer cylinder 1. It is designed to prevent

The catalytic converter 19 according to this embodiment is configured in this way, and the catalytic converter 19 is manufactured by the following method. In accommodating the ceramics carrier 13 carrying the catalyst in the outer cylinder 1, first, the belt-shaped heat-expandable mat 11 is placed in the ceramics carrier 1
Although it is wound around the outer periphery of the heat-expandable mat 3, the end portions 11a and 11b in the longitudinal direction of the heat-expandable mat 11 have convex locking pieces 21 and concave portions to prevent the exhaust gas G from being bypassed. Engagement portions 23 are provided respectively, and by winding the thermally expandable mat 11 around the outer periphery of the ceramics carrier 13 and locking them, the bypass of the exhaust gas G from between the end portions 11a and 11b is prevented. It

After the heat-expandable mat 11 is wound around the ceramic carrier 13 in this manner, these are inserted into the outer cylinder 1 from the front portion of the outer cylinder 1. It should be noted that the thermally expandable mat 11 is formed with a predetermined thickness so that the ceramics carrier 13 does not fall out from the rear portion of the outer cylinder 1 when the ceramics carrier 13 is thus inserted into the outer cylinder 1. The thickness of the ceramic carrier 13 is from the front of the outer cylinder 1.
It is set so that it will not interfere with the insertion of.

Next, the front end of the inner shell 15 is inserted from the inside of the outer shell 3 into the exhaust gas inlet 3a of the outer shell 3 to which the front flange 5 has been welded, and the ceramic carrier 1 is attached to the rear end of the inner shell 15.
Insert the outer shell 3 into the outer cylinder 1 by loosely inserting the front end of
Weld to a predetermined position on the outer circumference of the front part. After that, the inner shell 15 is pushed in with a predetermined hydraulic pressure using a pressure jig inserted from the exhaust gas inlet 3a, and the pressurization of the inner shell 15 is stopped when the heat-expandable mat 11 reaches a predetermined density, In this state, the front end of the inner shell 15 is welded to the inner circumference of the exhaust gas inlet 3a of the outer shell 3.

Finally, the diffuser 9 to which the rear flange 7 is welded is welded to a predetermined position on the outer periphery of the outer cylinder 1 to manufacture the catalytic converter 19 according to the present embodiment.
By mounting this on the vehicle exhaust system, exhaust gas can be purified. Then, as the exhaust gas G flows into the catalytic converter 19, the thermally expanded inner shell 15 pressurizes the thermally expandable mat 11 in the axial direction, and the packing density of the thermally expandable mat 11 due to the thermal expansion of the outer cylinder 1 is increased. Prevent decline,
In addition, the inner shell 15 directly guides the exhaust gas G to the ceramic carrier 13, and the exhaust gas G is transferred to the thermal expansion mat 1
1 to prevent hitting the front end.

Therefore, according to this embodiment, it is possible to prevent the packing density of the heat-expandable mat 11 from being lowered due to the heat expansion of the outer cylinder 1, and to prevent the erosion (wind erosion) of the heat-expandable mat 11. It is possible to In addition, in this embodiment, after inserting the ceramics carrier 13 around which the heat-expandable mat 11 is wound into the outer cylinder 1 formed into a tapered shape, the inner wall is adjusted so that the heat-expandable mat 11 has a predetermined packing density. Since the pressure is applied by the shell 15, it is possible to easily insert the ceramic carrier 13 into the outer cylinder 1 even if the ceramics carrier 13 has an elliptical cross section, as compared with the conventional pressure method. When the gap between the ceramic carrier and the container is, for example, 3 mm, the ceramic carrier wound with the thermally expandable mat having a thickness of 5 mm is press-fitted together with the thermally expandable mat. Although it took time to work and the press-fitting jig was large and required a large hydraulic pressure, according to the present embodiment,
The outer cylinder 1 is formed into a tapered shape, and the heat-expandable mat 1 is still used.
Since only 1 is required to be press-fitted, the heat-expandable mat 11 can be press-fitted and filled with a force smaller than the conventional one, and workability is significantly improved.

In the above embodiment, the outer cylinder 1 having an elliptical cross section and the ceramic carrier 13 are used. However, the present invention can be applied to a catalytic converter using an outer cylinder having a circular cross section or a ceramic carrier. In the above embodiment, the outer cylinder 1 and the diffuser 9 are separate bodies, but they may be integrally molded.

[0021]

As described above, according to the catalytic converter of the first aspect, it is possible to prevent the packing density of the heat-expandable mat from being lowered due to the heat expansion of the outer cylinder, and to reduce the heat-expandable mat. It is possible to prevent erosion.

Further, in the catalytic converter according to the first aspect of the present invention, since the outer cylinder is formed in a taper shape, it can be easily inserted into the outer cylinder when manufacturing, even if the ceramic carrier has an elliptical cross section. Since only the heat-expandable mat needs to be press-fitted, the heat-expandable mat can be press-fitted and filled with a force smaller than the conventional one, and workability is significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a catalytic converter according to claim 1.

FIG. 2 is a perspective view of a ceramics carrier and a heat-expandable mat.

[Explanation of symbols]

 1 Outer Cylinder 3 Outer Shell 9 Diffuser 11 Thermal Expansion Mat 13 Ceramics Carrier 15 Inner Shell 17 Flange 19 Catalytic Converter

Claims (1)

[Claims] 1. A taper-shaped outer cylinder (1) having a gradually decreasing diameter from a front part to a rear part, and a thermally expandable mat (1) press-fitted and filled in the outer cylinder (1).
1), the ceramic carrier (13) held in the outer cylinder (1) and the outer shell (3) attached to the front part of the outer cylinder (1).
And is mounted coaxially with the ceramic carrier (13), the front end is fixed to the front inner periphery of the outer shell (3), and the front peripheral side of the thermal expandable mat (11) is attached to the rear peripheral edge. An inner shell (15) formed with an annular flange portion (17) that abuts against the end portion and presses it in the axial direction of the ceramics carrier (13), and a diffuser (9) attached to the rear portion of the outer cylinder (1). )
And a catalytic converter comprising: