JP6136957B2 - Engine exhaust gas purification device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an exhaust gas purification device for an engine, and in particular, an engine including an oxidation catalyst means and a purification means disposed on the downstream side of the oxidation catalyst means and purifying the exhaust gas using the heat of the exhaust gas. The present invention relates to an exhaust gas purification apparatus.

The exhaust gas discharged from diesel engines (internal combustion engines) mounted on trucks and buses contains particulate matter (particulate matter) mainly composed of carbon particles. A DPF (Diesel Particulate Filter) that captures using a quality ceramic collection filter has been put to practical use.
In this DPF, when particulate matter, so-called soot accumulates on the filter, the particulate matter is burned to regenerate the DPF in order to avoid clogging of the filter.

  As a regeneration method, a regeneration method is known in which a catalyst having an oxidation function, for example, an oxidation catalyst (DOC: Diesel Oxidation Catalyst) is disposed upstream of the DPF, and the filter is regenerated while capturing particulate matter. In such a regeneration system, when the amount of accumulated particulate matter increases, post fuel injection is performed in the expansion stroke after main fuel injection for generating torque, and unburned fuel (HC) is discharged into the exhaust passage. To do. When this HC reaches the oxidation catalyst, the HC oxidizes and raises the exhaust gas temperature, so that the particulate matter deposited on the filter reaches the combustion temperature and is incinerated and removed by combustion.

The oxidation catalyst exhibits an oxidation function at the activation temperature (about 250 to 300 ° C.), and the particulate matter burns at about 600 ° C. Therefore, by shortening the exhaust gas path, heat radiation to the outside is suppressed and the exhaust gas is exhausted. The heat of gas is effectively used for DPF regeneration.
The engine exhaust gas purification device of Patent Document 1 includes an oxidation catalyst disposed in the vicinity of the engine, a DPF disposed in parallel and adjacent to the oxidation catalyst, a downstream end of the oxidation catalyst, and an upstream end of the DPF. A substantially U-shaped connecting pipe to be connected, and a heat shield plate that covers the front side region of the DPF and the lower side of the DPF and covers substantially the entire upper side region of the diesel engine.

A technique for oxidizing the particulate matter deposited on the filter using ozone has also been proposed.
The exhaust gas purifying device for an engine of Patent Document 2 includes ozone supply means capable of supplying ozone, and a DPF composed of a honeycomb structure disposed downstream of the ozone supply means, and the honeycomb structures are alternately arranged. The front end open cell and the rear end open cell are arranged, and the envelope connecting the front end of the plug of the front end open cell is configured to substantially match the velocity distribution curve of the exhaust gas flowing through the honeycomb structure. .

JP 2012-7536 A JP 2007-132241 A

The engine exhaust gas purification device of Patent Document 1 suppresses the decrease in the temperature of the exhaust gas introduced into the DPF and maintains the temperature inside the DPF at a high temperature, so that the heat of the oxidation reaction and the exhaust gas exhausted from the engine It is possible to remove the particulate matter trapped in the DPF by using both heat and combustion.
However, in the exhaust gas purification device for an engine of Patent Document 1, the particulate matter accumulated on the filter causes a so-called uneven accumulation in which the accumulation amount becomes non-uniform depending on the position captured by the DPF, and the regeneration performance of the DPF. May decrease.

That is, when the connecting pipe connecting the downstream end of the oxidation catalyst device and the upstream end of the DPF is formed in a substantially U shape, the exhaust gas flowing through the connecting pipe has an inertia depending on the distance from the center of curvature of the connecting pipe. Since the force acts, the exhaust gas flowing through the curved center side portion of the connecting pipe has a lower flow velocity than the exhaust gas flowing through the other part.
Therefore, at the time of DPF regeneration, a large amount of exhaust gas is supplied to the particulate matter deposited on the filter part separated from the curved center of the connecting pipe (on the side opposite to the curved center of the connecting pipe). Heat necessary for combustion is transferred. Further, only a small amount of exhaust gas is supplied to the particulate matter deposited on the curved center side filter portion of the connecting pipe, and the particulate matter is not heated to the combustion temperature, so that the particulate matter remains in the DPF, and the connecting pipe The amount of deposition increases by concentrating on the curved central filter portion.

If particulate matter concentrates and accumulates on the curved center filter part of the connecting pipe, there is a risk that fuel consumption will deteriorate due to an increase in exhaust gas flow path resistance. Since it may burn, there is a possibility that the DPF may be damaged by excessive combustion.
Although it is conceivable to apply the technique of Patent Document 2 that makes the flow of exhaust gas uniform to the exhaust gas purification device of the engine of Patent Document 1, it is difficult to say that it is a sufficient measure from the viewpoint of ensuring purification performance.

The exhaust gas purifying device for the engine of Patent Document 2 is provided so that the envelope connecting the front end of the plug of the front end open cell substantially matches the exhaust gas velocity distribution curve, so that it passes through the partition wall of the front end open cell. The exhaust gas flow rate per unit time is the same regardless of the position in the radial direction, and the amount of particulate matter deposited on the partition walls of the front end open cell is made uniform.
However, in the engine exhaust gas purification device of Patent Document 2, although the amount of particulate matter deposited can be made uniform, there is a possibility that the trapping performance of the particulate matter may be reduced with respect to the occupied space by the filter. That is, the exhaust gas purifying device of this engine substantially matches the envelope connecting the front end of the plug of the front end open cell with the exhaust gas velocity distribution curve, so the total length of the plug that does not capture particulate matter is increased, There is a problem that the partition wall portion that captures the particulate matter is less than the total length of the front end open cell.

  An object of the present invention is to provide an engine exhaust gas purification device and the like that can achieve both compactness and purification performance.

The engine exhaust gas purification device according to claim 1 is an engine exhaust gas purification device comprising an oxidation catalyst means and a purification means disposed on the downstream side of the oxidation catalyst means and purifying the exhaust gas. A curved connecting pipe connecting the downstream end of the casing containing the oxidation catalyst means and the upstream end of the casing containing the purification means, and a gas pressure adjusting mechanism capable of adjusting the exhaust gas pressure on the downstream end side of the purification means The gas pressure adjusting mechanism has an exhaust gas suction portion for sucking exhaust gas in the vicinity of the curved central side portion of the downstream end portion of the purification means, and the downstream end portion of the purification means The exhaust gas pressure in the curved center side portion of the connecting pipe with respect to the central axis of the purifying means is configured to be smaller than the exhaust gas pressure in the other portions.

In this engine exhaust gas purification device, the curved connecting pipe connects the downstream end of the casing containing the oxidation catalyst means and the upstream end of the casing containing the purification means, so that the oxidation catalyst means arranged in series And the purification means can be disposed in the vicinity of the engine, and the heat of the exhaust gas discharged from the engine due to the shortening of the piping can be used for the oxidation treatment and the purification treatment.
Moreover, since the gas pressure adjusting mechanism is disposed on the downstream end side of the purification means, exhaust gas can be introduced into the purification means without loss of heat due to obstacles.
In addition, since the gas pressure adjusting mechanism has an exhaust gas suction portion that sucks exhaust gas in the vicinity of the curved center side portion of the downstream end portion of the purification device, the exhaust gas is not increased without increasing the exhaust resistance. The flow of water can be adjusted with high accuracy, and the purification performance can be improved.
Further, since the exhaust gas is allowed to pass from the upstream end to the downstream end of the purifying means, and the amount of exhaust gas passing through the purifying means can be adjusted to be substantially equal regardless of the separation distance from the center of curvature of the connecting pipe, the entire purifying means. It is possible to purify the exhaust gas by using and improve the purification performance for the occupied space of the purification means.

The invention of claim 2 is characterized in that, in the invention of claim 1, the oxidation catalyst means and the purifying means are arranged substantially parallel and adjacent to each other.
As a result, it is possible to further reduce the size of the exhaust gas purification device and secure the heat of the exhaust gas.

A third aspect of the invention is characterized in that, in the first or second aspect of the invention, the purification means is a particulate filter.
Thereby, both compactness and the regeneration performance of the particulate filter that captures the particulate matter can be achieved.

According to the exhaust gas purification apparatus for an engine of the present invention, both compactness and purification performance can be achieved.

It is the schematic which shows each structure of the intake device and exhaust device which were attached to the engine in this embodiment. 2 is a longitudinal sectional view of a main part of an exhaust gas purification apparatus according to Reference Technology 1. FIG. It is sectional drawing of the axial center orthogonal | vertical direction of DPF. It is a graph which shows the comparison verification result of the reference technique 1 and a conventional structure. It is another graph which shows the comparison verification result of the reference technique 1 and a conventional structure. It is a 2 equivalent diagram according to the reference technique 2. FIG. 3 is a view corresponding to FIG. 2 according to the present embodiment .

Hereinafter, reference techniques and embodiments of the present invention will be described in detail with reference to the drawings.
The following description is merely illustrative in nature and does not limit the present invention, its application, or its use.

First, the outline of each component attached to the engine 1 will be described.
FIG. 1 shows each configuration of an engine 1 and an intake device 2 and an exhaust device 3 attached thereto. The engine 1 is an in-line four-cylinder diesel engine mounted on an automobile, and four cylinders 1a for taking out power by burning a mixture of fuel and intake air are arranged in a row. Note that illustration of the fuel supply system is omitted.

  The engine 1 is provided with two intake ports 1b and two exhaust ports 1c for each cylinder 1a. Each intake port 1b is connected to an intake device 2, and intake air is introduced into each cylinder 1a through the intake device 2 and each intake port 1b. Each exhaust port 1c is connected to the exhaust device 3, and the exhaust generated in each cylinder 1a is led out through the exhaust device 3 and each exhaust port 1c, and after being subjected to processing such as cleaning, it is discharged into the atmosphere. The

  An air cleaner 7 is disposed at the most upstream portion in the intake passage of the intake device 2. The air cleaner 7 removes dust and dirt from the outside air and introduces purified air (intake air) into the intake passage. The downstream side of the air cleaner 7 is connected to the supercharger 8 via the first intake pipe 2a, and the intake air is supercharged by a compressor 8a provided in the supercharger 8. The downstream side of the supercharger 8 is connected to the intake unit 4 via the second intake pipe 2b. The downstream side of the intake unit 4 is connected to the intake port 1b via the third intake pipe 2c. In the intake unit 4, a chamber (not shown), an intercooler (not shown), a valve unit 6, and the like are integrally unitized.

The exhaust device 3 includes a first exhaust pipe 3a connected to each exhaust port 1c, and the exhaust generated in each cylinder 1a is introduced into the first exhaust pipe 3a. The downstream side of the first exhaust pipe 3 a is connected to the supercharger 8. The turbocharger 8 is provided with a turbine 8b that operates using exhaust gas, and the compressor 8a is driven by the turbine 8b.
An exhaust gas purifying device 5 according to the reference technique 1 is disposed in the second exhaust pipe 3b connected to the downstream side of the supercharger 8. A third exhaust pipe 3 c connected to the downstream side of the exhaust gas purification device 5 is connected to the silencer 9. The outlet of the silencer 9 is open to the atmosphere, and the exhaust gas introduced into the exhaust device 3 is discharged to the outside from this outlet. A second exhaust pressure sensor 16 is provided at the upstream end of the third exhaust pipe 3c.

The exhaust device 3 of the engine 1 is provided with a high pressure EGR device 11 and a low pressure EGR device 12. The high pressure EGR device 11 is a device that introduces high pressure EGR gas into the intake air. Before the exhaust gas passes through the supercharger 8, the DOC (Diesel Oxidation Catalyst) device 21, and the DPF (Diesel Particulate Filter) device 22, the high pressure EGR device 11 is connected to the supercharger. The exhaust gas is recirculated from the upstream side such as 8 to the high pressure portion (third intake pipe 2 c) on the downstream side of the intake passage 2.
The high pressure EGR device 11 includes a high pressure EGR pipe 11a, a high pressure EGR cooler 11b, a high pressure EGR valve 11c, and the like.

The high-pressure EGR pipe 11a has one upstream end connected to the first exhaust pipe 3a and takes in part of the exhaust immediately after being led out from each cylinder 1a. The other end on the downstream side of the high-pressure EGR pipe 11 a is connected to a first gas inlet 13 provided in the third intake pipe 2 c on the downstream side of the intake unit 4.
The high pressure EGR cooler 11b cools the high pressure EGR gas flowing through the high pressure EGR pipe 11a. The high pressure EGR valve 11c adjusts the flow rate of the high pressure EGR gas flowing through the high pressure EGR pipe 11a. The high-pressure EGR gas that has undergone cooling and flow rate adjustment joins the intake air through the first gas inlet 13.

  The low pressure EGR device 12 is a device that introduces low pressure EGR gas into the intake air. After the exhaust gas passes through the supercharger 8, the DOC device 21, and the DPF device 22 and is depressurized and cleaned, the low pressure EGR device 12 is connected to the upstream side of the intake passage from the downstream side of the supercharger 8 and the like. The exhaust gas is recirculated to the low pressure part (first intake pipe 2a) on the side. The low pressure EGR device 12 includes a low pressure EGR pipe 12a, a low pressure EGR cooler 12b, a low pressure EGR valve 12c, and the like.

  One end of the low-pressure EGR pipe 12a is connected to the third exhaust pipe 3c, and takes in part of the exhaust before being decompressed and cleaned and discharged to the outside. The other end on the downstream side of the low pressure EGR pipe 12 a is connected to a second gas inlet 14 provided in the first intake pipe 2 a located on the upstream side of the supercharger 8. The low pressure EGR cooler 12b cools the low pressure EGR gas flowing through the low pressure EGR pipe 12a. The low pressure EGR valve 12c adjusts the flow rate of the low pressure EGR gas flowing through the low pressure EGR pipe 12a. The low pressure EGR gas that has undergone cooling and flow rate adjustment joins the intake air through the second gas inlet 14.

Next, a specific configuration of the exhaust gas purification device 5 according to the reference technique 1 will be described.
As shown in FIGS. 1 and 2, the exhaust gas purifying device 5 includes a DOC device 21 containing a columnar DOC 21a (oxidation catalyst means) that removes CO and HC in the exhaust, and particulate matter in the exhaust. A DPF device 22 containing a cylindrical DPF 22a (purifying means) to be removed, and a connecting pipe 23 connected in series with the DOC device 21 and the DPF device 22 are provided.

The DOC device 21 is disposed in the vicinity of the engine 1 so that its axis C1 is substantially horizontal, and is fixed to the side wall of the engine 1 via a bracket.
The DOC 21a has a common axis C1 with the DOC device 21, and oxidizes CO and HC in the exhaust gas of the engine 1 to generate CO ₂ , H ₂ O and heat. The DOC 21a is housed in a cylindrical casing 31 that opens along the flow direction of the exhaust gas, and is configured by supporting a catalyst metal (for example, Pt, Pd, etc.) on a honeycomb-shaped carrier.

The DPF device 22 is fixed to the side wall of the engine 1 via a bracket below the DOC device 21. The DPF device 22 is disposed substantially parallel and adjacent to the DOC device 21, and an upstream end thereof is connected to a downstream end of the DOC device 21 via a connection pipe 23.
The DPF 22 a has a common axis C <b> 2 (center axis) with the DPF device 22, and collects particulate matter such as soot contained in the exhaust gas of the engine 1. The DPF 22a is housed in a cylindrical casing 32 that opens along the flow direction of the exhaust gas, and is formed by a wall flow filter formed of a heat-resistant ceramic material such as silicon carbide (SiC) or cordierite. And a catalyst containing Pt as a noble metal.

The connecting tube 23 is formed in a substantially U shape having a curved portion 23a.
A bending center C3 of the bending portion 23a of the connecting pipe 23 is set to be a height position between the axis C1 of the DOC device 21 and the axis C2 of the DPF device 22. A first exhaust pressure sensor 15 is provided at the downstream end of the connection pipe 23.

As shown in FIG. 2, a vertical wall 33 as a gas pressure adjusting mechanism is provided inside the casing 32. This vertical wall portion 33 makes the exhaust gas pressure in the upper part of the downstream end of the DPF 22a above the axis C2 smaller than the exhaust gas pressure in the lower part of the axis C2, that is, below the DPF 22a. The back pressure of the part is configured to be higher than the back pressure of the upper part of the DPF 22a.
The vertical wall portion 33 rises vertically from the lower end portion of the inner peripheral wall of the casing 32 in the vicinity of the height position of the axis C2 and is formed in a substantially semicircular shape when viewed from the front. The vertical wall portion 33 is provided in the vicinity of the downstream side of the DPF 22a and faces the exhaust gas flow substantially orthogonally.

  The engine 1 has particles captured by the DPF 22a due to a differential pressure between the exhaust gas pressure upstream of the DPF 22a detected by the first exhaust pressure sensor 15 and the exhaust gas pressure downstream of the DPF 22a detected by the second exhaust pressure sensor 16. The accumulation amount of the particulate matter is evaluated, and it is determined that the regeneration condition of the DPF 22a is satisfied when the differential pressure becomes equal to or higher than a predetermined pressure. When it is determined that the regeneration condition for the DPF 22a is satisfied, the engine 1 performs post fuel injection from each injector (not shown) that does not contribute to combustion (no torque is generated) during the expansion stroke of each cylinder 1a.

Next, verification results of the predicted effects of the exhaust gas purification device 5 of the engine 1 will be described with reference to FIGS.

First, preconditions for verification will be described.
As shown in FIG. 3, the DPF 22a is formed by bonding twelve segments A to L parallel to the axis C2, and each segment A to L is a plurality of partition walls extending in the direction of the axis C2. Each is composed of a plurality of front-end open cells and rear-end open cells that are divided and arranged alternately.
The DPF 22a was divided into four in the direction of the axis C2, and the average value of the amount of soot (particulate matter) deposited in each segment A to L was calculated as the remaining amount remaining in each segment A to L. .

For the conventional structure in which the vertical wall portion 33 is omitted, the residual tendency α1 of the segments C, D, E, and F adjacent in the horizontal direction along the horizontal line X1 and the segments G, H, and the adjacent segments in the horizontal direction along the horizontal line X2 I, J residual tendency α2, the residual tendency β1 of segments A, D, H, K adjacent in the vertical direction along the vertical line Y1, and segments B, E, adjacent in the vertical direction along the vertical line Y2. The residual tendency β2 of I and L was determined respectively.
Further, with respect to the reference technique 1 provided with the vertical wall portion 33, the residual tendency α3 of the segments C, D, E, and F adjacent in the horizontal direction along the horizontal line X1 and the segment adjacent in the vertical direction along the vertical line Y1. The residual tendency β3 of A, D, H, and K was determined respectively.
For convenience, the remaining amounts of the other segments are calculated by setting the remaining amount of the segments D and E when the vertical wall portion 33 is provided as x.

As shown in FIG. 4, when the vertical wall portion 33 is omitted, only a small amount of exhaust gas is supplied to the soot deposited on the upper portion (the portion on the curved center C3 side of the connecting pipe 33) of the axis C2 of the DPF 22a. Therefore, since the soot is not heated up to the combustion temperature, more soot remains in the DPF 22a than the portion below the axis C2.
Further, since the heat of the exhaust gas is taken away by the casing 32 and the like in the radially outer (outer peripheral) portion of the DPF 22a, the remaining amount of soot is larger than that in the radially inner (inner peripheral) portion.
When the vertical wall portion 33 is provided, the back pressure in the lower portion of the DPF 22a is higher than the back pressure of the upper portion than the axis C2 of the DPF 22a, so that the exhaust gas introduced into the casing 32 is higher than the axis C2 of the DPF 22a. Heat can be applied to the soot that is guided to the upper portion and deposited on the upper portion of the axis C2 of the DPF 22a, and can be burned. In particular, the improvement effect of the radially outer portion of the DPF 22a is more remarkable than the radially inner portion of the DPF 22a.

As shown in FIG. 5, when the vertical wall portion 33 is omitted, more wrinkles remain in the upper portion of the DPF 22a than the axis C2 compared to the lower portion. The remaining tendency α1 and the remaining tendency α2 are structurally symmetrical with respect to the axis C2 of the DPF 22a, and therefore show substantially the same tendency.
In particular, the improvement effect on the upper side of the axis C2 of the DPF 22a is more remarkable than the improvement effect on the lower side of the axis C2 of the DPF 22a.

  According to the exhaust gas purification device 5 of the engine 1, since the curved connecting pipe 23 connects the downstream end of the DOC 21 a and the upstream end of the DPF 22 a, the DOC 21 and the DPF 22 a arranged in series are connected to the vicinity of the engine 1. The heat of the exhaust gas discharged from the engine 1 due to the shortening of the piping can be used for the oxidation treatment and the purification treatment. Moreover, since the vertical wall portion 33 is disposed on the downstream end side of the DPF 22a, exhaust gas can be introduced into the DPF 22a without loss of heat due to an obstacle. Further, since the exhaust gas is allowed to pass from the upstream end to the downstream end of the DPF 22a and the amount of exhaust gas passing through the DPF 22a can be adjusted to be substantially equal regardless of the separation distance from the curved center C3 of the connection pipe 23, the entire DPF 22a can be adjusted. The exhaust gas can be purified by using it, and the purification performance for the occupied space of the DPF 22a can be enhanced.

Since the DOC 21a and the DPF 22a are disposed substantially parallel and adjacent to each other, it is possible to further reduce the size of the exhaust gas purification device 5 and secure the heat of the exhaust gas transmitted from the engine 1.
Since the purification means is the DPF 22a, it is possible to achieve both compactness and the regeneration performance of the particulate filter that captures the particulate matter.

The gas pressure adjusting mechanism has a vertical wall portion 33 that is provided in the vicinity of the lower portion of the downstream end portion of the DPF 22a from the axis C2 and faces the flow of exhaust gas.
Thus, since the upstream side of the DPF 22a is not enlarged, the DOC 21a and the DPF 22a can be arranged close to each other to achieve both compactness and purification performance, and since the structure is simple, the productivity of the exhaust gas purification device is improved. Can be improved.

Next, reference technique 2 of the exhaust gas purification device will be described with reference to FIG. The same major components as those in the reference technique 1 are denoted by the same reference numerals, description thereof is omitted, and only different components are described.
In the exhaust gas purification device 5, the example in which the gas pressure adjusting mechanism is the vertical wall portion 33 has been described. However, in the exhaust gas purification device 5 </ b> A, the inclined portion 32 b is provided as the gas pressure adjusting mechanism.

As shown in FIG. 6, the DPF device 22A includes a casing 32A and a DPF 22a housed inside the upstream end portion of the casing 32A.
The casing 32A has a cylindrical portion 32a that forms an upstream end portion, and a partial conical inclined portion 32b that forms a downstream end portion. The inclined portion 32b is formed so that the height position becomes higher toward the downstream side from the downstream end of the lower half of the cylindrical portion 32a in the side view in the vicinity of the height position of the axis C2. The upper half of the downstream end portion of the casing 32A is formed in a partial cylindrical shape.

  According to the exhaust gas purifying apparatus 5A, the inclined portion 32b of the casing 32A makes the space in the lower part of the axis C2 of the DPF 22a narrower than the space of the upper part, so that the space below the axis C2 of the DPF 22a. Since the back pressure of the side portion is higher than that of the upper portion, the exhaust gas is guided to the upper portion of the axis C2 of the DPF 22a without using a new member, and is accumulated on the upper portion of the axis C2 of the DPF 22a. Heat can be supplied to the soot and the soot can be burned.

Next, based on FIG. 7, a description will be given of the exhaust gas purification equipment according to the embodiment.
In the present exhaust gas purification device 5B, the low pressure EGR device 12 is used as a gas pressure adjusting mechanism.

As shown in FIG. 7, the low-pressure EGR pipe 12 a includes an exhaust gas suction portion 12 d that penetrates the upper portion on the downstream end side of the casing 32 at the upstream end thereof. The tip of the exhaust gas suction part 12d is disposed in the vicinity of the downstream end of the DPF 22a so as to face the upper part of the axis C2.
The DPF device 22B includes a casing 32, a DPF 22a housed inside the upstream end portion of the casing 32, and an exhaust gas suction unit 12d (low pressure EGR device 12).
Since the low-pressure EGR pipe 12a is connected to the second gas inlet 14 provided in the first intake pipe 2a on the upstream side of the compressor 8a, the low-pressure EGR pipe 12a forcibly sucks the exhaust gas by the exhaust gas suction part 12d. can do.

  According to this exhaust gas purification device 5B, the exhaust gas can be circulated with high precision in the portion where soot accumulates without increasing the downstream back pressure of the DPF 22a, in other words, without increasing the exhaust resistance. The purification performance can be improved.

Next, a modified example in which the embodiment is partially changed will be described.
1) In the above embodiment, an example in which a DOC and a DPF are mounted on a diesel engine has been described. However, an engine having at least an oxidation catalyst means and a purification means for purifying exhaust gas using heat of the exhaust gas. Since it can be applied if there is, it may be applied to a gasoline engine without being limited to a diesel engine.

2] In the above embodiment, the example in which the DOC and the DPF are arranged substantially horizontally and adjacently has been described. However, at least when the exhaust gas that has passed through the DOC enters the DPF, it is captured according to the difference in the flow velocity. It is possible to apply the present invention to an exhaust gas purification device in which soot is unevenly distributed (unevenly accumulated).
Accordingly, the connection pipe connecting the DOC and the DPF has a curved portion, for example, an arrangement in which the axis of the DOC and the axis of the DPF intersect at a predetermined angle, or the DOC and the DPF are substantially vertical. In addition, the present invention may be applied to an exhaust gas purification device disposed adjacently.

3) In the above-described reference technology , the example in which the vertical wall portion that is the gas pressure adjusting mechanism is formed from the lower end portion to the vicinity of the height position of the shaft center is described. It may be set arbitrarily based on engine specifications.
Similarly, the inclined portion can be formed from the downstream end of the lower half of the cylindrical portion to a height position below the axial center in a side view.

4] In the above embodiment, the example in which the exhaust gas is sucked using the suction force of the compressor of the turbocharger has been described, but the suction force of other types of turbochargers may be used, and the intake air It is also possible to use negative intake pressure near the port.
5] In addition, those skilled in the art can implement the present invention with various modifications added without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

1 Engine 5, 5A, 5B Exhaust gas purification device 12 Low pressure EGR device 12d Exhaust gas suction part 21 DOC device 21a DOC
22, 22A, 22B DPF device 22a DPF
23 Connecting pipe 31 (DOC) casing 32, 32A (DPF) casing 32b Inclined portion 33 Vertical wall portion

Claims (3)

In an engine exhaust gas purification device comprising an oxidation catalyst means and a purification means disposed downstream of the oxidation catalyst means and purifying exhaust gas,
A curved connecting pipe connecting the downstream end of the casing containing the oxidation catalyst means and the upstream end of the casing containing the purification means;
A gas pressure adjusting mechanism capable of adjusting the exhaust gas pressure on the downstream end side of the purifying means,
The gas pressure adjusting mechanism has an exhaust gas suction portion that sucks exhaust gas in the vicinity of the curved central side portion of the downstream end portion of the purification means, and the purification of the downstream end portion of the purification means. An exhaust gas purifying apparatus for an engine, characterized in that the exhaust gas pressure at the curved center side portion of the connecting pipe with respect to the central axis of the means is made smaller than the exhaust gas pressure at other portions.   The engine exhaust gas purifying apparatus according to claim 1, wherein the oxidation catalyst means and the purifying means are arranged substantially parallel and adjacent to each other.   The engine exhaust gas purification device according to claim 1 or 2, wherein the purification means is a particulate filter.