JP7616978B2 - Exhaust Gas Purification Device - Google Patents

Description

This disclosure relates to an exhaust gas purification device.

In an exhaust gas purification device that uses a catalyst to purify the exhaust gas from an automobile's internal combustion engine, the catalyst is housed in a catalyst case via a buffer member (see Patent Documents 1 and 2).

Japanese Utility Model Application Publication No. 48-085011 Japanese Patent Application Publication No. 05-163939

In conventional exhaust gas purification devices, in order to prevent the catalyst from shifting downstream with the flow direction of the exhaust gas, the end face of the catalyst is in contact with a downstream cone or buffer member connected to the catalyst case in the flow direction of the exhaust gas (i.e., the axial direction of the catalyst case).

When the end face of the catalyst comes into contact with the downstream cone or the buffer member in this way, part of the exhaust gas flow path in the catalyst is blocked. In addition, the catalyst is easily chipped due to vibrations of the exhaust gas purification device. This reduces the purification performance of the catalyst. Furthermore, chipped catalyst can cause problems such as catalyst blockage and abnormal noise.

One aspect of the present disclosure aims to provide an exhaust gas purification device that can suppress deterioration of and damage to the purification performance of a catalyst.

One aspect of the present disclosure is an exhaust gas purification device that includes a cylindrical catalyst case into which exhaust gas from an internal combustion engine is introduced, a catalyst stored in the catalyst case, a buffer member that holds the catalyst by contacting the outer surface of the catalyst and the inner peripheral surface of the catalyst case, and a downstream cone that is connected to the downstream side of the catalyst case in the flow direction of the exhaust gas.

The upstream end of the downstream cone in the exhaust gas flow direction is inserted into the catalyst case and contacts the buffer member or faces the buffer member in the axial direction of the catalyst case with a gap between them. A gap is provided between the catalyst and the end of the downstream cone in the radial direction of the catalyst case.

With this configuration, the end of the downstream cone restricts the downstream movement of the buffer member, thereby preventing the catalyst held by the buffer member from shifting downstream. In addition, the catalyst is positioned away from the downstream cone in both the axial and radial directions of the catalyst case, preventing the catalyst from being damaged or losing its purification performance.

In one aspect of the present disclosure, the end of the downstream cone may be curved toward the inside or outside of the downstream cone. With this configuration, the buffer member comes into contact with the curved portion of the end, which can prevent damage to the buffer member.

In one aspect of the present disclosure, the ends of the downstream cones may be folded back so that the inner circumferential surfaces or the outer circumferential surfaces of the downstream cones overlap. This configuration can enhance the effect of suppressing damage to the cushioning member.

FIG. 1 is a schematic front view of an exhaust gas purification device according to an embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 3A is a schematic enlarged partial view of the vicinity of the end of the downstream cone in FIG. 2, and FIG. 3B is a schematic enlarged partial view of the vicinity of the end of the downstream cone in an embodiment different from that in FIG. 3A. 4A is a schematic enlarged partial view of the vicinity of the end of a downstream cone in an embodiment different from that in FIG. 3A, and FIG. 4B is a schematic enlarged partial view of the vicinity of the end of a downstream cone in an embodiment different from that in FIG. 3A.

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.
[1. First embodiment]
[1-1. Configuration]
An exhaust gas purification device 1 shown in FIG. 1 is provided in an exhaust gas passage of an internal combustion engine.

The exhaust gas purification device 1 purifies exhaust gas. Examples of internal combustion engines to which the exhaust gas purification device 1 is connected include gasoline engines and diesel engines used in automobiles.

The exhaust gas purification device 1 comprises an upstream cone 2, a catalytic converter 3, and a downstream cone 4.

<Upstream cone>
The upstream cone 2 is a member into which exhaust gas from an internal combustion engine is introduced. The upstream cone 2 is disposed on the most upstream side in the exhaust gas purification device 1 in the flow direction of the exhaust gas.

The upstream cone 2 is a truncated cone-shaped cylinder with an opening on both the top and bottom and a diameter that increases from the upstream side to the downstream side. The upstream cone 2 has an inlet 21 that introduces exhaust gas into the upstream cone 2. The inlet 21 is provided at the upstream end of the upstream cone 2. The inlet 21 is connected to an exhaust manifold or the like that is connected to the internal combustion engine.

<Catalytic converter>
The catalytic converter 3 is disposed downstream of the upstream cone 2. As shown in Fig. 2, the catalytic converter 3 has a catalyst case 31, a catalyst 32, and a buffer member 33. Note that the upstream cone 2 is not shown in Fig. 2.

(Catalyst case)
The catalyst case 31 is a cylindrical member connected to the upstream cone 2. An upstream end of the catalyst case 31 is fixed to a downstream opening of the upstream cone 2 by welding or the like. Exhaust gas G is introduced into the catalyst case 31 from the upstream cone 2. The catalyst case 31 houses a catalyst 32 and a buffer member 33.

(catalyst)
The catalyst 32 purifies the exhaust gas G by coming into contact with the exhaust gas G and reforming or capturing environmental pollutants in the exhaust gas G.

The catalyst 32 is stored in the catalyst case 31, and defines multiple flow paths within the catalyst case 31 through which the exhaust gas G flows in the axial direction of the catalyst case 31. In other words, the catalyst 32 has multiple flow paths that extend from the upstream cone 2 to the downstream cone 4, and that are either not connected to each other or connected to each other.

The catalyst 32 has a three-dimensional shape consisting of a collection of multiple tubes whose cross section perpendicular to the flow direction of the exhaust gas G is polygonal (e.g., rectangular, hexagonal, etc.). In other words, the catalyst 32 has a three-dimensional shape (e.g., a honeycomb shape) in which multiple partition plates extending in the axial direction of the catalyst case 31 are arranged in a lattice pattern.

For example, a gasoline particulate filter (GPF) is used as the catalyst 32. GPFs are mainly composed of cordierite ceramic. The use of GPFs improves the particulate matter (PM) collection performance, making it easier to comply with exhaust gas regulations that have become stricter in recent years. However, because GPFs have low strength, measures must be taken to prevent damage during assembly and use.

(Cushioning material)
The buffer member 33 is a cylindrical member that covers the entire circumferential direction of the outer surface of the catalyst 32. The buffer member 33 holds the catalyst 32 by contacting the outer surface of the catalyst 32 and the inner circumferential surface of the catalyst case 31. The downstream end of the buffer member 33 is located upstream of the downstream end of the catalyst 32. In other words, the catalyst 32 protrudes downstream of the buffer member 33.

The buffer member 33 is elastically deformable in the radial and axial directions of the catalyst case 31. In other words, the buffer member 33 is softer and less rigid than the catalyst case 31 and the catalyst 32. The buffer member 33 is wrapped around the outer surface of the catalyst 32 and is press-fitted into the catalyst case 31.

The surface roughness of the outer surface of the catalyst 32 is greater than the surface roughness of the inner peripheral surface of the catalyst case 31. Therefore, in the axial direction of the catalyst case 31, the frictional force of the buffer member 33 against the catalyst 32 is greater than the frictional force of the buffer member 33 against the catalyst case 31. Therefore, the buffer member 33 slides against the catalyst case 31 while holding the catalyst 32. For example, the buffer member 33 is made of aluminum fiber woven into a mat shape.

<Downstream cone>
The downstream cone 4 is a member connected to the downstream side of the catalyst case 31 of the catalytic converter 3. The downstream cone 4 is a truncated cone-shaped cylinder that is open on both the upper and lower sides and whose diameter decreases from the upstream side to the downstream side.

The upstream opening of the downstream cone 4 is connected to the downstream end of the catalyst case 31. The downstream opening of the downstream cone 4 forms an exhaust port 41 through which the exhaust gas G is discharged from the exhaust gas purification device 1.

The upstream end 42 of the downstream cone 4 forms the upstream opening of the downstream cone 4 and is inserted into the catalyst case 31. As shown in FIG. 3A, the outer peripheral surface of the end 42 contacts the inner peripheral surface of the downstream end 31A of the catalyst case 31. The downstream cone 4 and the catalyst case 31 are welded at a welded portion W that includes the edge of the downstream end 31A of the catalyst case 31.

The end face of the end 42 of the downstream cone 4 is in contact with the downstream end face of the buffer member 33. In other words, the end 42 abuts against the buffer member 33 from the downstream side. The end face of the end 42 overlaps with the catalyst 32 in the radial direction of the catalyst case 31.

The end 42 of the downstream cone 4 is disposed between the catalyst 32 and the catalyst case 31 in the radial direction of the catalyst case 31. In addition, a gap S1 is provided between the catalyst 32 and the end 42 of the downstream cone 4 in the radial direction of the catalyst case 31.

In other words, the catalyst 32 faces the end 42 in the radial direction of the catalyst case 31. Specifically, the catalyst 32 is not in contact with the end 42 in the radial direction of the catalyst case 31, and no other members exist between the catalyst 32 and the end 42.

As shown in FIG. 3B, the end 42 of the downstream cone 4 may face the buffer member 33 with a gap S2 in the axial direction of the catalyst case 31. In other words, a gap S2 may be provided between the buffer member 33 and the end 42 in the axial direction of the catalyst case 31. Such a gap S2 may be formed due to variations in the dimensions and assembly positions of the components that make up the exhaust gas purification device 1.

When a gap S2 exists between the buffer member 33 and the end 42 in this way, the buffer member 33 shifts downstream and comes into contact with the end 42. As a result, the buffer member 33 is restricted from shifting further downstream.

As shown in FIG. 4A, the end 42 of the downstream cone 4 may be curved toward the inside of the downstream cone 4 (i.e., in a direction away from the catalyst case 31). In FIG. 4A, the end face 421 of the end 42 faces the catalyst 32 across a gap in the radial direction of the catalyst case 31, and a part of the outer circumferential surface of the end 42 is in contact with the buffer member 33. Note that other parts such as the buffer member 33 and a reinforcing member may be disposed between the end face 421 and the catalyst 32.

Furthermore, as shown in FIG. 4B, the end 42 of the downstream cone 4 may be folded back in a U-shape around the folded back portion 42A so that the inner circumferential surfaces of the downstream cone 4 overlap. In FIG. 4B, the folded back portion 42A of the end 42 (i.e., the bottom of the "U") is in contact with the buffer member 33. The folded back portion 42A may also face the buffer member 33 with a gap therebetween.

The folded portion 42A faces the catalyst 32 across a gap in the radial direction of the catalyst case 31. Note that other parts such as a buffer member 33 and a reinforcing member may be disposed between the folded portion 42A and the catalyst 32.

In FIG. 4B, a gap may exist between the base portion 42B of the end portion 42 and the overlap portion 42C. The base portion 42B is the portion that contacts the outer peripheral surface of the catalyst case 31. The overlap portion 42C is the portion beyond the folded portion 42A, and is the portion that overlaps the base portion 42B from the radially inner side of the catalyst case 31.

<Production Method>
The exhaust gas purification device 1 can be obtained, for example, by the following manufacturing method. First, the buffer member 33 is wound around the circumferential surface of the catalyst 32. Next, the catalyst 32 with the buffer member 33 wound around it is press-fitted into the catalyst case 31. After that, the upstream cone 2 and the downstream cone 4 are welded to the catalyst case 31.

According to this manufacturing method, the catalyst 32 wrapped with the buffer member 33 is pressed into the catalyst case 31, thereby reducing the holding force of the catalyst 32 by the buffer member 33 and reducing the external force on the catalyst 32, thereby suppressing damage to the catalyst 32. Therefore, even when using a low-strength catalyst 32 such as GPF, it can be manufactured using the same equipment and procedures as when using a high-strength catalyst 32. In addition, the number of parts and welding points can be the same as in the conventional method.

<Action>
When the exhaust gas purification device 1 is in use, the catalyst 32 tends to move downstream due to the pressure of the exhaust gas flowing inside the exhaust gas purification device 1 (that is, the air resistance of the catalyst 32).

In response to this, the buffer member 33 that holds the catalyst 32 also tries to move downstream together with the catalyst 32, but the movement of the buffer member 33 is restricted by the contact of the end 42 of the downstream cone 4. As a result, the movement of the catalyst 32 is also restricted by the frictional force between the catalyst 32 and the buffer member 33.

[1-2. Effects]
According to the embodiment described above in detail, the following effects can be obtained.
(1a) The end 42 of the downstream cone 4 restricts the downstream movement of the buffer member 33, thereby suppressing the downstream shift of the catalyst 32 held by the buffer member 33. In addition, the catalyst 32 is disposed away from the downstream cone 4 in both the axial and radial directions of the catalyst case 31, thereby suppressing the deterioration of the purification performance of the catalyst 32 and damage to the catalyst 32.

(1b) In the case where the end 42 of the downstream cone 4 shown in FIG. 3A comes into contact with the buffer member 33, the effect of suppressing the displacement of the catalyst 32 can be improved.

(1c) In the case where the end 42 of the downstream cone 4 shown in FIG. 4A is curved toward the inside of the downstream cone 4, the buffer member 33 comes into contact with the curved portion of the end 42, and the buffer member 33 is less likely to come into contact with the edge portion of the end face 421, so damage to the buffer member 33 can be suppressed. In this way, the catalyst case 31 and the downstream cone 4 can be easily joined while suppressing damage to the buffer member 33.

(1d) In the case shown in FIG. 4B where the end 42 of the downstream cone 4 is folded back so that the inner circumferential surfaces of the downstream cone 4 overlap, the buffer member 33 is less likely to come into contact with the edge portion of the end face 421 than in the case shown in FIG. 4A, and therefore the effect of preventing damage to the buffer member 33 can be improved.

2. Other embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(2a) In the exhaust gas purification device 1 of the above embodiment, the end 42 of the downstream cone 4 in FIG. 4A may be curved toward the outside of the downstream cone 4. In other words, the end face of the end 42 of the downstream cone 4 may face or be in contact with the inner peripheral surface of the catalyst case 31.

In addition, the end 42 of the downstream cone 4 in FIG. 4B may be folded back so that the outer peripheral surfaces of the downstream cones 4 overlap each other. That is, in FIG. 4B, the base portion 42B may be disposed outside the overlapping portion 42C. In addition, the end 42 of the downstream cone 4 may not be folded back completely, but may be curved in an arc shape.

(2b) In the exhaust gas purification device 1 of the above embodiment, the tip of the end 42 of the downstream cone 4 may be made of a mesh. In this case, the mesh serves as the end 42 of the downstream cone 4 and faces the buffer member 33 in contact with or across a gap.

(2c) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. In addition, part of the configuration of the above embodiments may be omitted. In addition, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical idea identified from the wording of the claims are embodiments of the present disclosure.

1... exhaust gas purification device, 2... upstream cone, 3... catalytic converter, 4... downstream cone,
21: inlet; 31: catalyst case; 31A: downstream end portion; 32: catalyst; 33: buffer member;
41...Discharge port, 42...End part, 42A...Folded part, 42B...Foundation part,
42C...overlapped portion, 421...end surface.

Claims (3)

A cylindrical catalyst case into which exhaust gas from an internal combustion engine is introduced;
A catalyst housed in the catalyst case;
a buffer member that holds the catalyst by contacting an outer surface of the catalyst and an inner peripheral surface of the catalyst case;
a downstream cone connected to a downstream side of the catalyst case in a flow direction of the exhaust gas;
Equipped with
An outer circumferential surface of the downstream cone constitutes a part of an outer surface of the exhaust gas purification device, and an inner circumferential surface of the downstream cone contacts the exhaust gas,
an upstream end of the downstream cone in a flow direction of the exhaust gas is inserted into the catalyst case and contacts the buffer member or faces the buffer member via a gap in an axial direction of the catalyst case;
An exhaust gas purification device, wherein the catalyst is not in contact with the downstream cone in the radial direction of the catalyst case, a gap is provided between the catalyst and the end of the downstream cone , and no other components are present between the catalyst and the end of the downstream cone. The exhaust gas purification device according to claim 1,
An exhaust gas purification device, wherein the end of the downstream cone is curved toward the inside or outside of the downstream cone. The exhaust gas purification device according to claim 2,
The end portion of the downstream cone is folded back so that inner circumferential surfaces or outer circumferential surfaces of the downstream cone overlap each other.

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