JP6460212B2 - Engine exhaust system - Google Patents

Description

  The present invention relates to an exhaust system for an engine.

  Conventionally, a particulate filter for purifying particulate matter in exhaust gas has been disposed upstream of an exhaust path of an automobile engine such as a diesel engine or a gasoline engine.

  Particulate matter in the exhaust gas is collected by the partition walls of the particulate filter and is deposited by incineration when a certain amount is deposited.

  It is known that the amount of particulate matter deposited is detected by detecting the differential pressure between exhaust gas upstream and downstream (exhaust gas pressure difference) from the particulate filter (for example, patents). Reference 1).

JP 2005-256805 A

  By the way, in order to detect the differential pressure between the upstream side and the downstream side of the particulate filter, exhaust gas is taken out from the upstream side and the downstream side, respectively, but depending on the structure of the exhaust system, the differential pressure may be detected. There is a concern that the reliability of the detected differential pressure is lowered due to the influence of the exhaust gas flow in the exhaust path.

  Therefore, an object of the present invention is to improve the reliability of the differential pressure detection means by suppressing adverse effects due to the exhaust gas flow.

  In order to solve the above-mentioned problems, the present invention provides a differential pressure detection exhaust gas extraction portion downstream of the particulate filter between the exhaust gas discharge port and the EGR gas discharge port, and accompanies the flow of the exhaust gas. The dynamic pressure is not greatly affected by the differential pressure detection.

The engine exhaust system disclosed herein is
A particulate filter that is disposed on the exhaust path of the engine and in which a filter body that collects particulates in the exhaust gas discharged from the engine is housed in a filter case;
A differential pressure detecting means for detecting a differential pressure between the exhaust gas upstream of the filter body in the exhaust gas flow direction and the exhaust gas downstream of the filter body in the exhaust gas flow direction;
The differential pressure detecting means includes
An upstream exhaust gas extraction portion for extracting exhaust gas upstream of the filter main body in the exhaust gas flow direction;
A downstream exhaust gas extraction portion for extracting exhaust gas downstream of the filter body in the exhaust gas flow direction;
A differential pressure detection unit that detects the differential pressure from the exhaust gas extracted by the upstream exhaust gas extraction unit and the downstream exhaust gas extraction unit;
An exhaust gas outlet and an EGR gas outlet are provided at the downstream end of the filter case,
The downstream exhaust gas extraction portion of the differential pressure detecting means is disposed between the exhaust gas discharge port and the EGR gas extraction port at the downstream end of the filter case.

  According to this, since the downstream side exhaust gas extraction part is disposed between the exhaust gas outlet and the EGR gas outlet, the exhaust gas for differential pressure detection taken out from the extraction part is the exhaust gas outlet and the exhaust gas outlet. The influence of dynamic pressure accompanying the flow of exhaust gas toward each EGR gas outlet is not greatly affected. This is advantageous for improving the reliability of differential pressure detection.

In one embodiment, an L-shaped exhaust pipe bent in an L shape connected to the upstream side of the filter case in the exhaust gas flow direction;
The outer side wall of the L-shaped bend in the L-shaped exhaust pipe, and a stepped portion recessed outwardly formed at a portion separated from the L-shaped bent portion toward the filter body,
An upstream exhaust gas extraction portion of the differential pressure detection means is provided in the step portion.

  According to this, the exhaust gas flows along the outer peripheral side wall of the L-shaped bend in the L-shaped exhaust pipe, but the flow of the exhaust gas becomes gentle in the vicinity of the step portion recessed outward of the outer peripheral side wall. Thus, the upstream side exhaust gas extraction part is provided in the step part where the flow of exhaust gas becomes gentle, so that the exhaust gas for detecting the differential pressure taken out from the extraction part accompanies the flow of exhaust gas. It will not be greatly affected by dynamic pressure.

In one embodiment, a catalyst for purifying exhaust gas is connected to the upstream portion of the L-shaped exhaust pipe,
As viewed in the axial direction of the particulate filter, the downstream portion of the catalyst overlaps a part of the upstream end surface of the filter body.

  According to this, since the distance from the upstream end of the catalyst to the downstream end of the particulate filter can be shortened, it is advantageous for downsizing the exhaust device, and the exhaust gas is used as a particulate filter in a state in which the temperature does not decrease so much. It can be made to flow, which is advantageous for regeneration of the filter (PM combustion removal).

In one embodiment, the particulate filter is placed sideways so that the exhaust gas passes laterally,
An L-shaped exhaust pipe bent in an L-shape connected to the upstream side of the filter case in the exhaust gas flow direction;
The upstream side exhaust gas extraction part and the downstream side exhaust gas extraction part of the differential pressure detection means are respectively disposed at the lower part of the L-shaped exhaust pipe and the lower part of the downstream end part of the filter case,
The differential pressure detection unit of the differential pressure detection means is disposed around the upper side of the particulate filter.

  According to this, the workability for the differential pressure detection unit is improved by arranging the differential pressure detection unit around the upper side of the particulate filter. Further, by ensuring a certain distance between each of the upstream side exhaust gas extraction unit and the downstream side exhaust gas extraction unit and the differential pressure detection unit, the piping workability for exhaust gas extraction is improved.

In one embodiment, an EGR gas outlet pipe connected to the EGR gas outlet and provided so as to pass through the side of the particulate filter corresponding to the outer peripheral side of the L-shaped bend in the L-shaped exhaust pipe. When,
An EGR pipe support member disposed on a side of the particulate filter and supporting the EGR gas extraction pipe;
An upstream exhaust gas outlet pipe connecting the upstream exhaust gas outlet and the differential pressure detector;
An extraction pipe support member fixed to the EGR gas extraction pipe and supporting the upstream side exhaust gas extraction pipe.

  According to this, the upstream side exhaust gas extraction pipe is supported by the EGR pipe support member via the extraction pipe support member and the EGR gas extraction pipe. The support structure of the upstream side exhaust gas extraction pipe using such an EGR gas extraction pipe makes it possible to reduce the size of the exhaust device and enhance its layout.

  According to the present invention, since the downstream exhaust gas outlet is disposed between the exhaust gas outlet and the EGR gas outlet, the exhaust gas for differential pressure detection extracted from the downstream exhaust gas outlet is exhaust gas. The influence of the dynamic pressure accompanying the flow of the exhaust gas toward the exhaust port and the EGR gas outlet is not greatly affected. This is advantageous for improving the reliability of differential pressure detection.

FIG. 1 is a side view schematically showing a state in which the exhaust emission control device according to the first embodiment is attached to an engine. FIG. 2 is a schematic plan view of FIG. FIG. 3 is a side view showing the exhaust emission control device of FIG. 1. FIG. 4 is a perspective view of the exhaust purification device of FIG. 3 as viewed from the upper left rear. FIG. 5 is a perspective view of the exhaust purification device of FIG. 3 as viewed from the left front. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a perspective view of the connecting pipe as viewed from the upper left front. FIG. 9 is a view of the GPF end portion as viewed from the front. FIG. 10 is a perspective view of the differential pressure detection device as viewed from the upper left rear. FIG. 11 is a perspective view of the differential pressure detection device viewed from the lower right rear. FIG. 12 is a cross-sectional view of the differential pressure sensor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

(Embodiment 1)
<Engine>
The engine to which the exhaust device 1 according to Embodiment 1 is applied is an in-line four-cylinder gasoline engine (in-line multi-cylinder engine) mounted on an automobile. This engine is placed horizontally in front of the FF vehicle.

  The present invention can be applied not only to a four-cylinder gasoline engine but also to other multi-cylinder engines and diesel engines. Further, the present invention is not limited to FF vehicles, and can be applied to vehicles adopting various layouts including motorcycles such as RR vehicles and 4WD vehicles.

  As shown in FIG. 1, the engine includes an engine body E having a cylinder block E1 and a cylinder head E2. Although not shown in detail, the engine includes a first cylinder to a fourth cylinder configured by a cylinder block E1 and a cylinder head E2. The first to fourth cylinders are arranged in series in this order from the front of the page to the back side in a direction perpendicular to the page of FIG. A cylinder chamber (not shown) of the cylinder block E1, a piston (not shown) in the cylinder bore, and a cylinder head E2 form a combustion chamber for each cylinder.

  The cylinder head E2 has four exhaust ports (not shown) connected to the four combustion chambers. Exhaust gas generated in the combustion chamber is discharged out of the vehicle through an exhaust path including the exhaust port.

<Exhaust path>
As shown in FIGS. 1 and 2, the exhaust device 1 according to the present embodiment is connected to the exhaust port, and a downstream exhaust system (not shown) having a tail pipe is connected to the downstream side thereof. Has been. Thus, the exhaust path of the engine is constituted by the above-described exhaust port, the exhaust device 1, and the downstream exhaust system.

<Exhaust device>
As shown in FIGS. 1 and 2, the exhaust device 1 according to the present embodiment has an exhaust manifold M connected to four exhaust ports of the engine body E, and a downstream end of the exhaust manifold M via a connection portion N. And an exhaust purification device Q connected thereto.

<Exhaust manifold and connections>
Exhaust gas discharged from the four combustion chambers of the engine through the exhaust port is sent from the exhaust manifold M to the catalyst device Q through the connection portion N. As shown in FIGS. 2 and 4, the exhaust manifold M is disposed on one end side in the cylinder row direction and connected to each of the four exhaust ports and connected to the four independent exhaust pipes. A collecting pipe extending downward is provided.

  The connecting portion N is a tubular member that introduces exhaust gas from the collecting pipe of the exhaust manifold M into the exhaust purification device Q.

<Direction>
In the description of the present specification, “vertical direction” and “front-rear direction” refer to the engine body E as a reference, the cylinder head E2 side is the upper side, the cylinder block E1 side is the lower side, and the engine body, as shown in FIG. A direction in which the E side is the front side and the exhaust manifold M side is the rear side is assumed. Further, as shown in FIG. 2, the “left-right direction” refers to the cylinder arrangement direction with respect to the engine body E, in other words, perpendicular to the paper surface of FIG. The direction to do. Further, “upstream” and “downstream” are referred to as “upstream side in the exhaust gas flow direction” and “downstream side in the exhaust gas flow direction” based on the flow direction of the exhaust gas discharged from the combustion chamber through the exhaust port. is there.

  In the present embodiment, the “front-rear direction” is, as shown in FIG. 1, a gasoline particulate filter 3 (hereinafter referred to as “GPF3”) as a particulate filter (hereinafter referred to as “PF”) described later. )) In parallel with the central axis L3.

<Exhaust gas purification device>
As shown in FIG. 6, the exhaust purification device Q has an L-shape that connects the three-way catalyst 2 connected to the outlet of the connection portion N, the GPF 3 disposed on the downstream side thereof, and the three-way catalyst 2 and the GPF 3. The exhaust pipe 4 is provided.

<Three-way catalyst>
The three-way catalyst 2 is a catalyst for purifying hydrocarbon HC, carbon monoxide CO, and nitrogen oxide NOx in the exhaust gas. Although the detailed description is omitted, the three-way catalyst 2 is a catalyst formed by coating a honeycomb carrier with a catalyst component formed by supporting a noble metal such as Pt, Pd, Rh on a support material made of a metal oxide. Etc. The three-way catalyst 2 is not particularly limited, and any known catalyst can be used.

  The three-way catalyst 2 is a cylindrical catalyst having a central axis L2, as shown in FIG. The shape of the three-way catalyst 2 is not particularly limited, but is preferably a cylindrical shape from the viewpoint of being easily disposed in the exhaust path and obtaining a uniform exhaust gas flow. The shape of the cross section perpendicular to the central axis L2 of the three-way catalyst 2 is not particularly limited, and any shape such as a perfect circle shape, an ellipse shape, a rectangular shape, or a polygonal shape can be adopted. From the viewpoint of obtaining an exhaust gas flow and suppressing the manufacturing cost, it is preferably a perfect circle or ellipse.

  As shown in FIG. 6, the catalyst body for purifying the exhaust gas of the three-way catalyst 2 has an upstream end face 2A and a downstream end face 2B. For convenience, the end face 2A on the upstream side of the catalyst body and the end face 2B on the downstream side of the catalyst body may be referred to as the end face 2A on the upstream side of the three-way catalyst 2 and the end face 2B on the downstream side of the three-way catalyst 2. Both end faces 2A and 2B are circular with the same diameter.

  The three-way catalyst 2 includes a front stage portion 21 arranged on the upstream side and a rear stage portion 22 arranged on the downstream side as a catalyst body. The front stage 21 is a three-way catalyst excellent in low-temperature activity that purifies low-temperature exhaust gas during low-load operation of the engine body E. Further, the rear stage 22 is a three-way catalyst excellent in high-temperature activity that purifies high-temperature exhaust gas during high-load operation or the like. In the present embodiment, the three-way catalyst 2 has a two-stage configuration including the front stage portion 21 and the rear stage portion 22, but is not limited to this, and may have a single catalyst configuration, Further, it may be a multistage configuration divided into three or more.

  Further, the three-way catalyst 2 includes a mat 23 that covers the entire outer periphery of the front stage portion 21 and the rear stage portion 22 as a catalyst main body, and a case 24 that covers the entire outer periphery of the mat 23.

  The exhaust gas temperature is around 400 ° C. during a light load operation of the engine, and becomes a high temperature around 800 ° C. during a high load operation of the engine. Then, the three-way catalyst 2 itself is always exposed to the high-temperature exhaust gas that has passed through the three-way catalyst 2, which may cause the three-way catalyst 2 to deteriorate due to heat damage.

  The mat 23 is for stably holding the front-stage part 21 and the rear-stage part 22 as the catalyst body even in an environment exposed to high-temperature exhaust gas. For example, the mat 23 has high heat resistance and heat retention such as ceramic. It is formed with the material which has.

  The case 24 is for holding the catalyst main body (the front stage portion 21 and the rear stage portion 22) and the mat 23, and is made of a metal such as iron or stainless steel, for example. As the mat 23 and the case 24, known ones may be used.

<GPF>
As shown in FIG. 6, the GPF 3 is disposed on the downstream side of the three-way catalyst 2, and traps particulate matter (hereinafter referred to as “PM”) in the exhaust gas that has passed through the three-way catalyst 2. A filter main body (purification device main body) 33 is provided. Although the detailed description of the filter body 33 is omitted, for example, a honeycomb carrier or the like is sealed and a filter function is added, and the filter body 33 may have a catalyst coat to promote combustion of trapped PM. Good. The PM in the exhaust gas is collected in the partition wall of the filter main body 33. When the PM is deposited, for example, after the main injection in which fuel is injected into the combustion chamber of the engine to obtain output, the filter main body in the expansion stroke of the engine Post injection for injecting fuel for increasing the temperature of 33 into the combustion chamber is performed, and PM deposited on the filter main body 33 is incinerated and removed. The filter body 33 is not particularly limited, and any known filter body can be used.

  The GPF 3 has a cylindrical shape having a central axis L3 as shown in FIGS. The shape of the filter main body 33 is not particularly limited, but is preferably cylindrical from the viewpoint of easy disposition in the exhaust path and obtaining a uniform exhaust gas flow. The shape of the cross section perpendicular to the central axis L3 of the filter body 33 is not particularly limited, and any shape such as a perfect circle shape, an ellipse shape, a rectangular shape, or a polygonal shape can be adopted. From the viewpoint of obtaining a gas flow and reducing the manufacturing cost, it is preferably a perfect circle or ellipse.

  As shown in FIG. 6, the filter body 33 of the GPF 3 has an upstream end surface 3A and a downstream end surface 3B. For convenience, the end face 2A on the upstream side of the filter body 33 and the end face 2B on the downstream side of the filter body 33 may be referred to as the end face 2A on the upstream side of the GPF 3 and the end face 2B on the downstream side of the GPF 3. Both end surfaces 3A and 3B are circular with the same diameter.

  Similar to the three-way catalyst 2, the GPF 3 includes a filter main body 33, a mat 34 covering the entire outer periphery of the filter main body 33, a cylindrical case 35 covering the entire outer periphery of the mat 34, and an end face on the downstream side of the filter main body 33. And a downstream cover 7 that covers 3B with a space. The cylindrical case 35 and the downstream cover 7 constitute a filter case that houses the filter body 33. The mat 34 and the cylindrical case 35 are used for the same purpose as the mat 23 and the case 24 of the three-way catalyst 2 described above, and those having the same configuration can be used.

<L-shaped exhaust pipe>
The L-shaped exhaust pipe 4 is a tubular member bent in an L-shape for connecting the three-way catalyst 2 and the GPF 3 and forms a part of the exhaust path.

  As shown in FIG. 6, the L-shaped exhaust pipe 4 includes an upstream opening 4A, a downstream opening 4B, and a bent portion 4C between the openings 4A and 4B. The bent portion 4C includes a first tubular portion 4C1 extending from the upstream opening 4A in the cylinder row direction (downstream side), a second tubular portion 4C2 extending from the downstream opening 4B toward the engine body, and the first A bent portion 4C3 that connects the tubular portion 4C1 and the second tubular portion 4C2 is provided. And the bending part 4C3 is provided with the outer peripheral side bending part 4C31 located in the outer peripheral side of L-shaped bending, and the inner peripheral side bending part 4C32 located in an inner peripheral side.

  As shown in FIG. 6, the three-way catalyst 2 has a downstream portion inserted into the L-shaped exhaust pipe 4 from the upstream opening 4 </ b> A. On the other hand, the upstream end of the GPF 3 is inserted into the L-shaped exhaust pipe 4 from the downstream opening 4B.

-Relative arrangement of three-way catalyst and GPF-
FIG. 7 is a view showing a VII-VII cross section in FIG. 2, and is a view as viewed from the left side of a cross section perpendicular to the central axis L2 of the three-way catalyst 2 and passing through the GPF 3 and the exhaust gas discharge pipe 5. The section described in FIG. 7 is hereinafter referred to as “VII-VII section”. A line indicated by reference sign PL32 in FIG. 7 indicates a plane including the central axis L3 of the GPF 3 and parallel to the central axis L2 of the three-way catalyst 2.

  As shown in FIG. 7, the position of the central axis L2 of the three-way catalyst 2 is below the plane PL32, that is, the GPF central axis L3 of GPF3 on the VII-VII cross section. Thereby, as will be described later, the exhaust manifold M can be disposed above the three-way catalyst 2, and the exhaust device 1 can be disposed compactly in the vehicle.

  As shown in FIG. 6, the end face 2B on the downstream side of the three-way catalyst 2 and the end face 3A on the upstream side of the GPF 3 are disposed so that the dihedral angle α is about 90 degrees in the bent portion 4C. . The dihedral angle α is not limited to this angle, but from the viewpoint of sufficiently securing the exhaust gas flow from the three-way catalyst 2 to the GPF 3, it is preferably 60 degrees or more and 120 degrees or less, more preferably It is 70 degrees or more and 110 degrees or less, Most preferably, they are 80 degrees or more and 100 degrees or less.

  In addition, the three-way catalyst 2 and the GPF 3 are disposed so that the downstream portion of the three-way catalyst 2 overlaps a part of the upstream end surface of the GPF 3 when viewed in the axial direction of the GPF 3. That is, an overlapping portion 31 is formed between the three-way catalyst 2 and the GPF 3.

  FIG. 6 is a view showing a VI-VI cross section in FIG. 3, and is a view of a cross section including the central axis L2 of the three-way catalyst 2 and parallel to the central axis L3 of the GPF 3 as viewed from above. The cross section shown in FIG. 6 is hereinafter referred to as “VI-VI cross section”. As shown in FIG. 6, the length H31 of the side surface of the three-way catalyst 2 forming the overlapping portion 31 on the VI-VI cross section is the exhaust gas in the GPF 3 while the three-way catalyst 2 and the GPF 3 are arranged in a compact manner. From the viewpoint of making the flow uniform, the total length H2 of the three-way catalyst 2 is preferably 10% or more and less than 50%.

  Further, the length H31 of the side surface of the three-way catalyst 2 is determined from the viewpoint of making the exhaust gas flow in the GPF 3 uniform while arranging the three-way catalyst 2 and the GPF 3 compactly in the VI-VI cross section of FIG. The width W3 is preferably 10% or more and less than 50%.

  As described above, when the three-way catalyst 2 and the GPF 3 are arranged in the lateral direction, the overlapping portion 31 of the three-way catalyst 2 and the GPF 3 is formed, thereby reducing the distance from the downstream end of the exhaust manifold M to the GPF 3. Can be In addition, while forming the overlapping portion 31, by suppressing the range to less than the above range, the exhaust device 1 can be made compact, and the use efficiency of the GPF 3, particularly the portion that becomes a shadow of the overlapping portion 31, can be improved. Can be made.

-1st pipe member and 2nd pipe member-
The L-shaped exhaust pipe 4 includes a first pipe member 40 and a second pipe member 41 as shown in FIGS. 6 and 8. That is, as shown in FIG. 6, the L-shaped exhaust pipe 4 is provided with a first pipe member 40 and a second pipe member 41 which are joined by providing a joining line on a substantially vertical surface passing through the substantially center of the downstream opening 4 </ b> B. It is comprised by. The joining line is in the vicinity of the end face 2B on the downstream side of the three-way catalyst 2 and passes downstream from the end face 2B.

  The first pipe member 40 forms the upstream side opening 4 </ b> A, and the downstream side opening 4 </ b> B is formed by joining the first pipe member 40 and the second pipe member 41. Specifically, the first pipe member 40 forms the upstream opening 4A, and forms a part of the downstream opening 4B and a part including the inner peripheral side bent part 4C32 of the bent part 4C. ing. The second pipe member 41 forms a remaining portion including the remaining portion of the downstream opening 4B and the outer peripheral side bent portion 4C31 of the bent portion 4C.

  Since the L-shaped exhaust pipe 4 is formed by the first pipe member 40 and the second pipe member 41, the L-shaped exhaust pipe 4 can be easily formed. Further, since the inner circumferential side bent portion 4C32 having a small curvature radius where stress is likely to concentrate is formed by the first pipe member 40, that is, since a joining line is provided avoiding a portion where stress is likely to concentrate, an L-shaped exhaust pipe 4 is advantageous for securing the durability.

  Further, in the present specification, in the state where the exhaust device 1 including the L-shaped exhaust pipe 4 shown in FIG. 8 is assembled to the engine body E, the positions located at the uppermost part and the lowermost part of the L-shaped exhaust pipe 4 are respectively shown. It shall be called top 4D and bottom 4E. In the present embodiment, the top portion 4D and the bottom portion 4E exist in the vicinity of the joint portion between the first tube member 40 and the second tube member 41.

-1st wall part and 2nd wall part-
As shown in FIGS. 6 and 8, the L-shaped exhaust pipe 4 includes a first wall portion 42 and a second wall portion 43 for guiding the exhaust gas that has passed through the three-way catalyst 2 to the GPF 3. . As shown in FIG. 6, the first wall portion 42 faces the end surface 2B on the downstream side of the three-way catalyst 2, and the second wall portion 43 faces the end surface 3A on the upstream side of the GPF 3, The outer peripheral side bent portion 4C31 is formed.

  The first wall portion 42 and the second wall portion 43 are formed on one second pipe member 41 constituting the L-shaped exhaust pipe 4. Accordingly, a smooth wall surface without a joining line can be obtained by the first wall portion 42 and the second wall portion 43, which is advantageous in suppressing disturbance of the exhaust gas flow.

  As shown in FIGS. 6 and 8, the first wall portion 42 facing the downstream end surface 2B of the three-way catalyst 2 continues to the upstream side wall portion 42C that forms the downstream side opening 4B and the outer peripheral side bent portion 4C31. 42 A of downstream wall parts and the inclined wall part 42B which connects both wall parts 42A and 42C smoothly are provided. The upstream side wall portion 42C travels to the three-way catalyst 2 side than the downstream side wall portion 42A. In other words, the downstream side wall portion 42A is a stepped portion that is recessed outward. These wall portions 42A, 42B, and 42C constitute a part of the second tubular portion 4C2.

  Since the upstream side wall portion 42C travels closer to the three-way catalyst 2 than the downstream side wall portion 42A, the exhaust gas that has passed through the three-way catalyst 2 and reached the upstream side wall portion 42C is upstream of the GPF 3 as shown in FIG. It becomes easy to go to the center side of the side end surface 3A. That is, it is suppressed that exhaust gas concentrates on the site | part corresponding to the outer peripheral side of the L-shaped curve in the L-shaped exhaust pipe 4 in GPF3, and the exhaust gas flow toward the site | part used as the shadow of the overlap part 31 of GPF3 is produced. Induced.

  As shown in FIGS. 6 and 8, an upstream side exhaust gas extraction part 81 of the differential pressure detecting device 8 described later shown in FIG. 2 is installed in the downstream side wall part 42A that is recessed outward from the upstream side wall part 42C. A pedestal 47 is provided, and an exhaust gas outlet 47 </ b> A for pressure detection is opened in the pedestal 47.

  As shown in FIG. 8, a pedestal 44 is provided on the second pipe member 41 on the top portion 4 </ b> D side of the L-shaped exhaust pipe 4. For example, a NOx sensor 92 (detection means) shown in FIG. The pedestal 44 is provided with an attachment port 92A for attaching the NOx sensor 92.

  The exhaust gas that has passed through the three-way catalyst 2 flows so as to roll up along the wall surface of the first wall portion 42 as shown by the solid line arrow in FIG. 6, and flows into the PF 3 from the L-shaped exhaust pipe 4. . Since the downstream side wall portion 42A of the L-shaped exhaust pipe 4 is farther from the three-way catalyst 2 than the upstream side wall portion 42C, the flow rate of the exhaust gas in the vicinity of the downstream side wall portion 42A is low. Therefore, the pressure on the upstream side of the GPF 3 can be stably obtained without being greatly affected by the flow of the exhaust gas by taking out the exhaust gas from the upstream side exhaust gas extraction part 81 installed on the pedestal 47 of the downstream side wall part 42A. Can be detected.

  Further, the exhaust gas from the three-way catalyst 2 is not directly applied to the vicinity of the base 44 where the NOx sensor 92 of the top portion 4D of the L-shaped exhaust pipe 4 is provided, so that it is greatly affected by the flow of the exhaust gas. Therefore, the NOx concentration in the exhaust gas can be detected stably.

  The pedestals 44 and 47 may be provided with control devices such as various sensors other than the upstream pressure extraction portion 81 and the NOx sensor 92. Thereby, stable detection accuracy can be ensured.

  The pedestals 44 and 47 are formed flat, but may be formed in a curved surface or the like.

<Downstream end of GPF>
As shown in FIGS. 6 and 7, the downstream cover 7 of the GPF 3 has an exhaust gas exhaust port 71 that guides the exhaust gas that has passed through the GPF 3 to the exhaust gas exhaust pipe 5, and an engine using a part of the exhaust gas as EGR gas. An EGR gas outlet 70 is provided to supply the intake system. The EGR gas outlet pipe 6 is connected to the EGR gas outlet 70 via an EGR gas inlet 72A.

<Exhaust gas exhaust pipe>
The exhaust gas discharge pipe 5 is for guiding the exhaust gas that has passed through the GPF 3 to the downstream exhaust system, and for collecting and removing moisture generated by the purification of the exhaust gas by the three-way catalyst 2 and the GPF 3.

  A line indicated by a symbol PRL31 shown in FIG. 6 is a projection line on the VI-VI cross section of the central axis L3 of the GPF3. A line indicated by a symbol L5 indicates the central axis of the exhaust gas discharge pipe 5. A point indicated by reference sign P5 is a point on the exhaust gas outlet central axis L5 and indicates the center of the inlet of the exhaust gas discharge pipe 5.

  As shown in FIG. 6, the center of the exhaust gas discharge port 71 is biased toward the three-way catalyst 2 side from the projection line PRL31 corresponding to the central axis L3 of the GPF3. Correspondingly, the center P5 of the inlet of the exhaust gas discharge pipe 5 is also deviated from the projection line PRL31 corresponding to the central axis L3 of the GPF 3 to the three-way catalyst 2 side.

  According to this structure, as shown in FIG.6 and FIG.9, the flow which goes to the exhaust-gas exhaust pipe 5 arises about the exhaust gas which flowed into GPF3. The exhaust gas flow toward the exhaust gas discharge pipe 5 increases the amount of exhaust gas flowing into the shadowed portion of the overlapping portion 31. Therefore, the utilization efficiency of GPF3 can be improved.

  The deviation amount of the center P5 of the exhaust gas discharge pipe 5 is preferably on the VV cross section from the viewpoint of ensuring a sufficient amount of exhaust gas flowing into the overlapping portion 31 and improving the utilization efficiency of the GPF 3. The right side surface 5A on the three-way catalyst 2 side of the exhaust gas discharge pipe 5 can be set to the right side of the GPF side surface 3C on the three-way catalyst 2 side of the GPF 3, that is, on the three-way catalyst 2 side. At this time, from the viewpoint of suppressing an increase in ventilation resistance in the vicinity of the exhaust gas discharge pipe 5, the left side surface 5B of the exhaust gas discharge pipe 5 is more than the side surface 3C of the GPF 3 on the three-way catalyst 2 side on the VV cross section. It is preferable to set the amount of deviation of the exhaust gas discharge pipe 5 so as to be located on the left side.

  Further, as shown in FIG. 7, the exhaust gas discharge pipe 5 is disposed below the plane PL32. In other words, as shown in FIG. 9, the center position P <b> 5 of the exhaust gas discharge pipe 5 is arranged below the center position O <b> 7 of the downstream cover 7. In this way, by arranging the exhaust gas discharge pipe 5 below the GPF 3, the water generated due to the purification of the exhaust gas by the three-way catalyst 2 and the GPF 3 is effectively accumulated and removed in the exhaust gas discharge pipe 5. can do.

<EGR>
As the configuration of the engine body E, EGR that recirculates a part of the exhaust gas to the intake system of the engine is employed for the purpose of preventing knocking and reducing the amount of nitrogen oxide NOx. An EGR gas extraction pipe 6 (EGR path) extending forward through the side (left side) of the GPF 3 is provided on the downstream side of the GPF 3.

  As shown in FIG. 6, the center of the EGR gas outlet 70 is biased to the opposite side of the exhaust gas outlet 71 from the projection line PRL31 corresponding to the central axis L3 of the GPF 3. The EGR gas extraction pipe 6 is connected to the EGR gas introduction port 72 at the tip of the EGR gas introduction part 72A protruding to the side of the GPF 3 (the side opposite to the side where the exhaust gas discharge pipe 5 is provided). . The EGR gas extraction pipe 6 extends in parallel with the central axis of the GPF 3 from the EGR gas introduction port 72 toward the engine body side on the side of the GPF 3. As shown in FIG. 9, the EGR gas inlet 72 is disposed below the center position O <b> 7 of the downstream cover 7 of the GPF 3.

  As a result, as indicated by solid arrows in FIG. 6, the EGR gas can be taken out in the inertia direction of the exhaust gas when the exhaust gas discharged from the three-way catalyst 2 passes through the L-shaped exhaust pipe 4. Therefore, a sufficient amount of EGR gas can be secured. Further, the EGR gas can be taken out while suppressing mutual interference with the exhaust gas flow to the exhaust gas discharge pipe 5. Furthermore, the flow of exhaust gas in the GPF 3 can be distributed to the left and right to be uniform, and the utilization efficiency, function, and performance of the GPF 3 can be further improved.

  As shown in FIGS. 6 and 9, a pedestal 77 having a downstream exhaust gas outlet 77A is provided between the exhaust gas outlet 71 and the EGR gas outlet 70 in the downstream cover 7 of the GPF 3, The pedestal 77 is provided with a downstream exhaust gas extraction portion 82 of the differential pressure detection device 8 described later. In the vicinity of the pedestal 77, the flow of the exhaust gas is branched into the exhaust gas discharge port 71 side and the EGR gas extraction port 70 side, and the flow rate of the exhaust gas tends to be gentle and uniform. Therefore, the exhaust gas pressure can be detected without being greatly affected by the pressure change of the exhaust gas by the exhaust gas extraction from the downstream side exhaust gas extraction part 82.

  A space 78 having a lower bottom than the EGR gas outlet 70 is formed below the pedestal 77. Even if the condensed water generated in the EGR path flows backward, it accumulates in the space portion 78, so that it is possible to prevent the EGR gas outlet 70 and the EGR gas introducing portion 72A from being blocked by the condensed water.

<Differential pressure detector>
As shown in FIGS. 1 to 5 and the like, the GPF 3 is provided with a differential pressure detecting device 8 for detecting the differential pressure of the exhaust gas upstream and downstream of the filter main body 33 of the GPF 3. From the differential pressure of the exhaust gas detected by the differential pressure detector 8, the amount of PM deposited on the GPF 3 is calculated.

  As shown in FIGS. 6, 10, and 11, the differential pressure detection device 8 includes an upstream exhaust gas extraction portion 81 that extracts exhaust gas upstream from the filter body 33, and exhaust gas downstream from the filter body 33. A downstream exhaust gas extraction unit 82 for extracting gas and a differential pressure sensor (differential pressure detection unit) 83 for detecting the differential pressure from the pressure of the exhaust gas extracted from both extraction units 81 and 82 are provided.

  The upstream exhaust gas extraction portion 81 is provided on the base 47 of the L-shaped exhaust pipe 4 as described above. On the other hand, the downstream exhaust gas extraction part 82 is provided on the base 77 of the downstream cover 7 of the GPF 3 as described above. As shown in FIGS. 10 and 11, the upstream side exhaust gas extraction part 81 and the differential pressure sensor 83 are connected by an upstream side exhaust gas extraction pipe 81A. The downstream side exhaust gas extraction part 82 and the differential pressure sensor 83 are connected by a downstream side exhaust gas extraction pipe 82A.

  As shown in FIG. 11 and the like, the upstream side exhaust gas extraction pipe 81A includes an extraction pipe 81A1 and an extraction pipe 81A2 connected to the extraction pipe 81A1. The downstream side exhaust gas extraction pipe 82A includes an extraction pipe 82A1 and an extraction pipe 82A2 connected to the extraction pipe 82A1.

  As shown in FIGS. 1 to 3, the differential pressure sensor 83 is disposed on the upper side of the GPF 3.

  As shown in FIG. 12, the differential pressure sensor 83 includes a double-sided pressure receiving type diaphragm 93, and a differential pressure detection film (not shown) having a strain gauge is provided on the surface of the diaphragm 93. The diaphragm 93 is fixed to the circuit board 94 with an adhesive 95. In the circuit board 94, an upstream pressure introduction hole 94 a for introducing the pressure of the exhaust gas extracted from the upstream exhaust gas extraction portion 81 is formed on the lower surface side of the diaphragm 93. The strain gauge of the diaphragm 93 and the circuit board 94 are connected by a bonding wire 95. A cover 96 that covers the diaphragm 93 and the bonding wire 95 is fixed to the circuit board 94 with an adhesive. The cover 96 is formed with a downstream pressure introduction hole 96 a for introducing the pressure of the exhaust gas taken out from the downstream exhaust gas extraction portion 82 to the upper surface side of the diaphragm 93. The diaphragm 93 and the bonding wire 95 are covered with a gel material 97.

  In the differential pressure sensor 83, distortion of the diaphragm 93 due to a pressure difference applied to the upper surface side and the lower surface side of the diaphragm 93 is detected by a strain gauge. That is, the pressure difference is detected as a change in electrical resistance due to deformation of the strain gauge.

  In FIG. 11, reference numeral 85 denotes a first support member fixed to the L-shaped exhaust pipe 4, and a second support member 84 is fixed to the first support member 85, and a differential pressure sensor is connected to the second support member 84. 83 is supported via a differential pressure sensor mounting plate 83A. As shown in FIG. 1, the second support member 84 is fixed to the cylinder block E1. Since the second support member 84 is coupled to the cylinder block E1 and the L-shaped exhaust pipe 4, the second support member 84 is also used to support the differential pressure sensor 83 and the L-shaped exhaust pipe 4 by the cylinder block E1.

  In FIG. 2, the differential pressure sensor mounting plate 83A is not shown.

  The upstream side exhaust gas extraction part 81 and the downstream side exhaust gas extraction part 82 are arranged at the upstream lower part and the downstream lower part of the GPF 3, respectively, from the viewpoint of stable pressure detection. On the other hand, the workability with respect to the differential pressure sensor 83 is improved by arranging the differential pressure sensor 83 on the side upper side of the GPF 3. Further, long extraction pipes 81A1 and 82A1 are extended from the upstream side exhaust gas extraction part 81 and the downstream side exhaust gas extraction part 82, and the lengths of the extraction pipes 81A2 and 82A2 connected to these are set long. The workability of the installation work of the differential pressure detecting device 8 including the pipe connection work and the like is improved.

  Further, the differential pressure sensor 83 and the upstream side exhaust gas extraction part 81 are arranged on the same side as the EGR gas extraction pipe 6 with respect to the GPF 3. Therefore, the upstream side exhaust gas extraction pipe 81 </ b> A can also be arranged so as to extend on the same side as the EGR gas extraction pipe 6.

  As shown in FIGS. 3 and 4, the EGR gas extraction pipe 6 is supported by an engine-related part such as a transmission outside the figure via an EGR pipe support member 61. As shown in FIGS. 10 and 11, a first support member 38 that supports the GPF 3 is attached to the EGR gas extraction pipe 6. Furthermore, an extraction pipe support member 81A3 that supports the upstream pressure extraction path 81A is fixed to the first support member 38. Then, as shown in FIG. 4, the upstream pressure extraction path 81 </ b> A is also supported by the EGR pipe support member 61. Thus, by using the EGR pipe support member 61 to support the upstream side exhaust gas extraction path 81A, the compactness and layout of the apparatus can be improved.

(Other embodiments)
Hereinafter, other embodiments according to the present invention will be described in detail. In the description of these embodiments, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Although the exhaust device 1 of the first embodiment is applied to an FF vehicle, the independent exhaust pipes of the exhaust manifold M connected to the four exhaust ports are assembled while extending rearward, and the center in the vehicle width direction at the rear of the engine body E It can also be applied to an FR vehicle by extending the side rearward.

  In Embodiment 1, the upstream catalyst is the three-way catalyst 2 and the downstream PF is GPF3. However, the catalyst and PF are not limited to these, and various catalysts and PF can be used. . For example, the upstream catalyst may be an oxidation catalyst or the like. In addition, when the exhaust purification device 1 is applied to a diesel engine, a diesel particulate filter may be employed as the PF.

  In the first embodiment, as shown in FIG. 9, the three-way catalyst 2 is provided slightly below the GPF 3. In this regard, the three-way catalyst 2 may be provided at the same height as the GPF 3 or at a position higher than the GPF 3. In any case, the mounting position of various sensors such as the pedestal portion 44 and the transition wall portion 42A is not limited to the top portion 4D side of the connection pipe 4, but the bottom portion 4E side, the first connection member 40, etc. It can be suitably provided at a position where the exhaust gas flow is made uniform.

  In the first embodiment, the downstream end outlet of the exhaust manifold M is disposed on the first cylinder side in the cylinder row direction of the engine, and the upstream opening 4A of the L-shaped exhaust pipe 4 faces the first cylinder side in the cylinder row direction. However, depending on the vehicle layout, the upstream opening 4A may face in another direction, for example, the first cylinder side, the upper side, or the lower side.

  In the first embodiment, the downstream end outlet of the exhaust manifold M is configured to be arranged on the right side of the cylinder arrangement, and the connection pipe 4 has the first opening 4A arranged on the right side as shown in FIG. Was configured to. In this regard, according to the vehicle layout, the first opening 4A may face in another direction, for example, the fourth cylinder side or the like.

  INDUSTRIAL APPLICABILITY The present invention is extremely useful because it can provide an engine exhaust device that suppresses adverse effects of exhaust gas flow, improves differential pressure detection accuracy, and is stabilized.

1 Engine exhaust system 2 Three-way catalyst 3 GPF (particulate filter)
3A Upstream end face 4 L-shaped exhaust pipe 4C Bent part 4C3 Bent part 5 Exhaust gas discharge pipe 6 EGR gas extraction pipe (EGR path)
7 Downstream cover (configures a filter case)
8 Differential pressure detection device (Differential pressure detection means)
31 Overlapping part 33 Filter body 35 Case (constituting filter case)
42A Downstream side wall (step)
42C Upstream side wall 61 EGR pipe support member 70 EGR gas outlet 71 Exhaust gas outlet 81 Upstream exhaust gas outlet 81A Upstream exhaust gas outlet pipe 81A3 Outlet pipe support member 82 Downstream exhaust gas outlet 83 Differential pressure sensor ( Differential pressure detector)
E Engine body E1 Cylinder block E2 Cylinder head M Exhaust manifold

Claims (5)

A particulate filter that is disposed on the exhaust path of the engine and in which a filter body that collects particulates in the exhaust gas discharged from the engine is housed in a filter case;
A differential pressure detecting means for detecting a differential pressure between the exhaust gas upstream of the filter body in the exhaust gas flow direction and the exhaust gas downstream of the filter body in the exhaust gas flow direction;
The differential pressure detecting means includes
An upstream exhaust gas extraction portion for extracting exhaust gas upstream of the filter main body in the exhaust gas flow direction;
A downstream exhaust gas extraction portion for extracting exhaust gas downstream of the filter body in the exhaust gas flow direction;
A differential pressure detection unit that detects the differential pressure from the exhaust gas extracted by the upstream exhaust gas extraction unit and the downstream exhaust gas extraction unit;
An exhaust gas outlet and an EGR gas outlet are provided at the downstream end of the filter case,
The engine, wherein the downstream exhaust gas extraction portion of the differential pressure detecting means is disposed between the exhaust gas discharge port and the EGR gas discharge port at the downstream end of the filter case. Exhaust system. In claim 1,
An L-shaped exhaust pipe bent in an L-shape connected to the upstream side of the filter case in the exhaust gas flow direction;
The outer side wall of the L-shaped bend in the L-shaped exhaust pipe, and a stepped portion recessed outwardly formed at a portion separated from the L-shaped bent portion toward the filter body,
An exhaust system for an engine, characterized in that an upstream side exhaust gas extraction portion of the differential pressure detecting means is provided in the stepped portion. In claim 2,
A catalyst for purifying exhaust gas is connected to the upstream portion of the L-shaped exhaust pipe,
An exhaust system for an engine, characterized in that a downstream portion of the catalyst overlaps a part of an upstream end surface of the filter body as viewed in the axial direction of the particulate filter. In any one of Claim 1 thru | or 3,
The particulate filter is placed horizontally so that the exhaust gas passes in the lateral direction,
An L-shaped exhaust pipe bent in an L-shape connected to the upstream side of the filter case in the exhaust gas flow direction;
The upstream side exhaust gas extraction part and the downstream side exhaust gas extraction part of the differential pressure detection means are respectively disposed at the lower part of the L-shaped exhaust pipe and the lower part of the downstream end part of the filter case,
The exhaust system for an engine according to claim 1, wherein the differential pressure detection unit of the differential pressure detection means is disposed around an upper side of the particulate filter. In claim 2,
An EGR gas outlet pipe connected to the EGR gas outlet and provided so as to pass through the side of the particulate filter corresponding to the outer peripheral side of the L-shaped bend in the L-shaped exhaust pipe;
An EGR pipe support member disposed on a side of the particulate filter and supporting the EGR gas extraction pipe;
An upstream exhaust gas outlet pipe connecting the upstream exhaust gas outlet and the differential pressure detector;
An exhaust system for an engine, comprising: an extraction pipe support member fixed to the EGR gas extraction pipe and supporting the upstream side exhaust gas extraction pipe.

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