CN111022165A

CN111022165A - Engine exhaust structure

Info

Publication number: CN111022165A
Application number: CN201911337703.2A
Authority: CN
Inventors: 张秀丽
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2020-04-17

Abstract

The invention relates to the technical field of automobile exhaust systems, in particular to an engine exhaust structure, which comprises: a turbine of a turbocharger that is provided for an exhaust pipe of an engine and that is rotated by exhaust energy of the engine; and an exhaust gas purifier directly connected to a downstream side of the turbine for purifying exhaust gas, the exhaust gas purifier including a housing having a flat cross section with a pair of opposite short sides and a pair of opposite long sides and configured to accommodate the catalytic converter, the inlet cone including a conical portion and configured to connect an outlet of the turbine to an inlet of the housing, the conical portion including an inclined wall inclined from a main flow of the exhaust gas to increase a portion of a lateral exhaust gas path. The present invention reduces the offset velocity profile of exhaust gas flowing into the exhaust purifier housing by a flat exhaust purifier connected directly downstream of the turbine.

Description

Engine exhaust structure

Technical Field

The invention relates to the technical field of automobile exhaust systems, in particular to an engine exhaust structure.

Background

In the conventional exhaust structure, an expansion portion having an increased diameter is provided immediately downstream of the turbine. A straightening vane for straightening a swirl flow discharged from the turbine is provided inside the expansion portion. An exhaust gas cleaner having a circular cross section is connected downstream of the expansion portion. The exhaust gas purifier is equipped with a catalytic converter. In the exhaust structure, the expansion portion straightens the flow of the exhaust gas, thereby making the velocity distribution of the exhaust gas passing through the exhaust purifier uniform. As a result, the catalyst exhibits sufficient purification performance. If the exhaust gas cleaner is connected directly downstream of the turbine, the exhaust gas cleaner is close to the engine. A flat exhaust gas purifier is conceivable in view of the arrangement inside the engine room. In an exhaust gas purifier, for example, a housing that houses a catalytic converter has a flat cross section including a pair of opposing short sides and a pair of opposing long sides. This arrangement effectively places the exhaust gas purifier near the engine in the small engine room. However, in the case where the exhaust gas purifier is directly connected downstream of the turbine, the exhaust gas flowing into the exhaust gas purifier becomes a strong swirling flow at a high turbine speed. If strong eddy currents flow into the flat exhaust gas cleaner, the exhaust gas velocity of the long side is higher than that of the short side in the exhaust gas cleaner. The present inventors have found this fact through various studies. If the exhaust gas passing through the exhaust gas purifier has a biased velocity distribution, the exhaust gas purification performance may be degraded. An increase in the flow volume of exhaust gas in a specific portion of the exhaust purifier may cause an excessive temperature increase at the specific portion, which leads to thermal damage.

Disclosure of Invention

The present invention provides an exhaust gas discharge structure of an internal combustion engine including a flat exhaust gas purifier directly connected downstream of a turbine to reduce an offset velocity distribution of exhaust gas flowing into an exhaust gas purifier housing.

In order to achieve the purpose, the invention provides the following technical scheme: an engine exhaust structure comprising: a turbine of a turbocharger that is provided for an exhaust pipe of an engine and that is rotated by exhaust energy of the engine; and an exhaust gas purifier directly connected to a downstream side of the turbine for purifying exhaust gas, the exhaust gas purifier including a housing having a flat cross section with a pair of opposite short sides and a pair of opposite long sides and configured to accommodate the catalytic converter, the inlet cone including a conical portion and configured to connect an outlet of the turbine to an inlet of the housing, the conical portion including an inclined wall inclined from a main flow of the exhaust gas to increase a portion of a lateral exhaust gas path.

Preferably, the recess includes: a first wall extending along a main flow of the exhaust gas and along the opposite long sides; and a second wall continuous with and extending outwardly from the first wall along the first wall.

Preferably, an expansion is provided between the outlet of the turbine and the inlet of the inlet cone, and the cross-section of the exhaust path is gradually increased in the expansion.

Preferably, the position of the turbine connected to the outlet of the conical portion is offset toward one of the facing short sides, i.e., the inlet of the air inlet, in a direction in which the facing short sides face each other. Inserting a conical portion between the opposing long sides, forming a first recess in a portion of one of the opposing long sides, through which exhaust gas from the inlet of the conical portion passes in a direction in which the exhaust gas swirls, thereby reaching one of the opposing short sides, and forming a second recess in a portion of the other of the opposing long sides, along which exhaust gas from the inlet of the conical portion passes, the gas swirls, reaching the other opposing short side, wherein the second recess is larger than the first recess.

Preferably, the concave portion is formed of an upstream concave portion and a lower concave portion, and the upstream concave portion is located upstream in a direction in which the exhaust gas rotates along the opposing long sides; the downstream concave portion is located downstream of the direction in which the exhaust gas rotates along the opposite long sides; the downstream groove is deeper than the upstream groove.

Preferably, an engine compartment including the engine includes the exhaust gas purifier and a second exhaust gas purifier connected downstream of the exhaust gas purifier.

Preferably, the engine is longitudinally installed, the housing of the exhaust purifier has a vertically long flat cross section, the exhaust purifier is placed at one side of the engine, and the engine and the exhaust purifier are surrounded and encapsulated by a partition.

Preferably, the turbine is placed above an exhaust manifold of the engine, the exhaust purifier is placed near a top of the engine, and an insulating wall covering the engine and the exhaust purifier is placed above the exhaust purifier.

The invention has the beneficial effects that: in this configuration, the exhaust gas cleaner is connected directly downstream of the turbine. The exhaust gas cleaner may be directly connected to the outlet of the turbine. This configuration increases the temperature of the exhaust gas flowing into the exhaust purifier, which is advantageous for earlier activation of the exhaust purifier. In addition, since the engine has high thermal efficiency, in an engine that discharges low-temperature exhaust gas, the connection of an exhaust gas purifier directly downstream of a turbine raises the temperature of exhaust gas flowing into the exhaust gas purifier. This is advantageous in maintaining the exhaust purifier in an operating state. An exhaust gas cleaner connected directly downstream of the turbine is located adjacent the engine. The exhaust gas purifier includes a housing having a flat cross-section. The flat housing effectively positions the exhaust gas purifier adjacent the engine in a smaller engine compartment. Exhaust gas from the turbine flows into a housing accommodating the catalytic converter through an intake cone while diffusing in a direction orthogonal to the main flow of the exhaust gas. At high turbine speeds, the exhaust gas flowing into the housing may spin strongly. Due to centrifugal forces, the exhaust gas flows to the peripheral region in the conical portion. In the flat condition, the long side portion is closer to the entrance of the entrance cone than the short side portion. When the exhaust gas strongly swirls, the speed of the exhaust gas is higher in the long side portion than in the short side portion in the case of the exhaust gas purifier.

In the above configuration, the concave portion that is depressed inward is formed in a portion corresponding to each long side of the inclined wall of the conical portion. In the intake cone, the exhaust gas flowing to the peripheral area due to the centrifugal force is restricted by the recess. The exhaust gas is directed through the grooves from long side to short side. This reduces the biased velocity distribution of the exhaust gas flowing into the flat case when the exhaust gas strongly swirls. This results in a uniform velocity distribution of the exhaust gas passing through the exhaust gas purifier, thereby maintaining high exhaust gas purification performance. This also reduces the local increase in the exhaust gas flow rate at the long side portion of the flat case. The recess may include: a first wall extending along a main flow of the exhaust gas and along a long side; and a second wall continuous with the first wall and extending outwardly from the first wall along the long side. With this configuration, the relatively strong vortex directs exhaust gas flowing along the first wall toward the peripheral region, which expands along the long side of the inlet cone. Since the exhaust gas flows from the long side to the short side, the velocity distribution of the exhaust gas flowing into the flat case becomes uniform. An expansion may be provided between the outlet of the turbine and the inlet of the inlet cone, and the cross-section of the exhaust gas path may gradually increase in the expansion. The velocity of the exhaust gas decreases as the exhaust gas passes through the expansion section. Thus, the exhaust gas tends to diffuse in a direction orthogonal to the main flow when passing through the inlet cone. This reduces the biased velocity distribution of the exhaust gas flowing into the housing of the exhaust gas purifier. The position of the turbine connected to the outlet of the conical portion may be moved towards one of the short sides in a direction in which the short sides face each other. The first side and the second side may be disposed in a direction in which the long sides face each other with the entrance of the tapered portion interposed therebetween. A first groove may be formed in a portion of one of the long sides, through which the exhaust gas from the inlet of the conical portion passes to one of the short sides in a direction in which the exhaust gas swirls. A second recess may be formed in a part of the other of the long sides, and the exhaust gas from the inlet of the conical portion passes in a swirling direction of the exhaust gas in the second recess to reach the other short side. Large notches, including deep and/or long notches, are more advantageous in restricting exhaust gas flow to the peripheral region and directing exhaust gas from the long side to the short side. When the position of the exhaust pipe connected to the conical portion is shifted to one of the short sides in the direction in which the short sides face each other, the second groove of larger size severely restricts the exhaust gas from flowing to the surrounding area and directs the exhaust gas to the other short side, which is farther from the inlet of the conical portion. On the other hand, the smaller first recess does not strictly restrict the flow of exhaust gas to the peripheral area and orients the exhaust gas towards the other short side closer to the inlet of the conical portion. When the position of the outlet of the turbine connected to the conical portion is offset from the center, the difference in size between the first recess and the second recess makes the velocity distribution flowing into the housing uniform. The recess may include: an upstream concave portion located upstream of the exhaust gas in the direction of the long-side vortex; and a downstream concave portion downstream in the direction of the long-side vortex of the exhaust gas. The downstream recess may be recessed deeper than the upstream recess. Since the downstream concave portion is recessed deeper than the upstream concave portion, exhaust gas is strictly restricted, and exhaust gas is oriented toward the short side. The combination of the upstream and downstream recesses improves the controllability of the exhaust flow in the tapered portion. This is advantageous in that the velocity distribution of the exhaust gas flowing into the housing is made more uniform. An engine compartment including an engine may include an exhaust purifier and a second exhaust purifier coupled downstream of the exhaust purifier. The second exhaust purifier may house a catalytic converter. The second exhaust purifier may house a filter. The second exhaust purifier in the engine compartment provides an under-floor space. This increases the cabin space. Both exhaust gas purifiers are placed in the engine compartment, which is advantageous for controlling the temperature of the exhaust gas purifiers. The engine may be mounted vertically. The housing of the exhaust gas purifier may have a vertically long flat cross section. The exhaust purifier may be placed at one side of the engine. The engine and the exhaust purifier are surrounded by a partition and are encapsulated. This is advantageous in maintaining the temperature of the engine and the exhaust purifier. It is advantageous for an efficient engine to maintain high temperatures of the engine and exhaust purifier during idle stop or idle operation. The engine is covered, which is advantageous for reducing noise during engine operation. An exhaust gas purifier having a vertically long flat shape requires a small space on the side of an engine mounted vertically. This increases the space efficiency in the engine compartment. In addition, the exhaust purifier has a small size but a large volume, thereby reducing the back pressure of the engine. The turbine may be placed above an exhaust manifold of the engine. The exhaust purifier may be placed near the top of the engine. An insulating wall covering the engine and the exhaust gas purifier is placed above the exhaust gas purifier. With this configuration, the exhaust gas flows into the turbine at high energy, and the turbocharged engine is provided at a small size in the vehicle width direction. The insulating wall covers the engine and the top of the exhaust purifier is close to the top of the engine, which is beneficial to maintaining the temperature of the engine and the exhaust purifier.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of an application scenario of the present invention;

FIG. 2 is a schematic view of the front left portion of the present invention;

FIG. 3 is a schematic right front portion of the present invention;

FIG. 4 is a left side schematic view of the present invention;

FIG. 5 is a right side view of the present invention;

FIG. 6 is a front view of the present invention;

fig. 7 is a cross-sectional view of the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, 2, 3, 4, 5, 6, and 7, an engine 1 mounted in a motor vehicle is a multi-cylinder internal combustion engine. Specifically, the engine 1 shown in these figures is an inline four diesel engine. However, the engine 1 is not limited to a diesel engine. The engine 1 may be a so-called gasoline engine. The engine 1 is mounted in an engine room 100 in the longitudinal direction. Corresponding to the front of the vehicle. The transmission 10 is attached to the rear end of the engine 1. An intake manifold 11 is mounted on the left side of the engine 1, the intake manifold 11 corresponding to the left side as viewed from the rear of the vehicle forward, and the upper portion is mounted on the intake manifold 11. 2. The intercooler 12 is placed above the intake manifold 11. Although not specifically shown, the intake pipe 13 is connected to the intake manifold 11 via the intercooler 12.

The exhaust manifold 14 is a part of an exhaust pipe that is mounted on the right side of the engine 1, which corresponds to the right side as viewed from the rear to the front. A turbocharger 15 is placed above the exhaust manifold 14. The turbocharger 15 is placed near the upper end of the engine 1. The rotational axis of the turbocharger 15 extends in the vehicle longitudinal direction. The turbocharger 15 is placed such that the turbine 151 is located in front of the compressor 152. The exhaust manifold 14 is connected to a turbine 151. The intake pipe 13 is connected to the compressor 152.

The exhaust gas purifier 2 is placed in front of the turbine 151. The exhaust gas cleaner 2 is connected directly downstream of the turbine 151. The exhaust gas purifier 2 includes an oxidation catalytic converter 24. The exhaust gas purifier 2 is placed at the upper portion. The exhaust gas purifier 2 has a flat cross section that is long in the vertical direction and short in the vehicle width direction. The specific structure of the exhaust gas purifier 2 will be described later.

A second exhaust gas purifier 31 is connected downstream of the exhaust gas purifier 2. The second exhaust gas purifier 31 is a Diesel Particulate Filter (DPF). On the right side of the engine 1, a second exhaust purifier 31 is located below the exhaust manifold 14. The second exhaust purifier 31 has a flat cross section that is long in the vertical direction and short in the vehicle width direction. The second exhaust purifier 31 extends in the vehicle front-rear direction. Although not shown, a space is provided at the bottom of the vehicle by the second exhaust purifier 31 as a DPF provided inside the engine room 100. This increases the cabin space. In addition, the design flexibility of the cabin space is increased to optimize the driving position of the driver.

As described above, each of the exhaust gas purifiers 2 and 31 has a flat cross section. The exhaust gas purifiers 2 and 31 are located on the right side of the engine 1. These exhaust gas purifiers 2 and 31 and the engine 1 have a small size in the vehicle width direction. This increases space efficiency in the small engine compartment 100.

In the flat shape, the exhaust gas purifier 2 has a smaller size but a larger volume. This configuration reduces the back pressure of the engine 1, thereby improving fuel efficiency.

In the engine room 100, the exhaust gas purifiers 2 and 31 and the engine 1 are surrounded by a heat insulating wall 32. Specifically, the heat insulating wall 32 extends from the upper left to the upper side of the engine 1. In the engine 1. In fig. 1, reference numeral 33 denotes a hood. The heat insulating wall 32 extends along the engine cover 33 between the engine 1 and the engine cover 33. The engine 1, the exhaust gas purifier 2, and the second exhaust gas purifier 31 are enclosed by an insulating wall 32.

The thermal efficiency of the engine 1 is very high. That is, the cooling loss and the exhaust loss of the engine 1 are low. Therefore, the engine 1 and the exhaust gas have relatively low temperatures. In order to maintain the engine 1 and the exhaust purifier 2 at high temperatures during idle stop and idle operation, the heat radiation from the engine 1 and the exhaust purifier 2 is reduced by the heat insulating wall 32. The heat insulating wall 32 keeps the engine 1 and the exhaust gas cleaner 2 at high temperatures, respectively.

Both the exhaust gas purifier 2 and the second exhaust gas purifier 31 are disposed in the engine room 100, thereby increasing the temperature of the exhaust gas flowing into these exhaust gas purifiers 2 and 31. This is advantageous in activating the exhaust gas purifier 2, and controls the temperatures of the exhaust gas purifier 2 and the second exhaust gas purifier 31. In addition, the packaging of the engine 1 is advantageous for reducing noise during operation of the engine 1.

The exhaust gas cleaner 2 comprises a housing 21, an inlet cone 4 and an outlet 23. The housing 21 accommodates a catalytic converter 24. The inlet cone 4 is attached to the upstream end of the housing 21. The outlet 23 is attached to the housing 21. At the downstream end of the housing 21, the outlet 23 extends vertically to connect the housing 21 to the second exhaust gas cleaner 31, the second exhaust gas cleaner 31 being located below the exhaust gas cleaner 2. The outlet 23 reverses the main flow of exhaust gas from the rear to the front of the vehicle to the front to the rear of the vehicle.

The housing 21 has a cylindrical shape with an open end. The upstream opening of the casing 21 serves as an inlet of the casing 21. The downstream opening of the housing 21 serves as an outlet of the housing 21. The housing 21 extends almost horizontally, specifically, slightly inclined downward toward the front of the vehicle. The housing 21 has a generally rectangular cross section having a pair of vertically facing short sides and a pair of laterally long sides. The housing 21 accommodates a catalytic converter 24. A holding mat 25 that holds the catalytic converter 24 is provided between the catalytic converter 24 and the inner peripheral surface of the housing 21. The holding mat 25 is made of a fibrous material.

The inlet cone 4 comprises a conical portion 41 and a straight portion 42. The conical portion 41 is attached to the inlet of the housing 21. The straight portion 42 connects the conical portion 41 and the outlet of the turbine. The straight portion 42 has a cylindrical shape with an open end. The axis of the straight portion 42 extends almost horizontally to extend substantially horizontally to the rotation axis of the turbine 151. Straight portion 42 has a much smaller cross-sectional area than housing 21. The axis of the straight portion 42 moves above the axis of the housing 21. As a result, the upper end of the housing 21 is located at a relatively low position. The axis of the housing 21 is inclined downward toward the front of the vehicle. The exhaust purifier 2 is placed below the engine hood 33 and near the front end of the engine 1 in the engine room 100. The hood 33 is inclined downward toward the front.

An expansion nozzle 153 as an expansion portion is provided at an outlet of the turbine 151, and the linear portion 42 is connected to the outlet. The inner circumferential surface of the expansion nozzle 153 divides the path of the exhaust gas and is inclined with respect to the vehicle front-rear direction so that the cross section of the path gradually increases.

As the exhaust gas passes through the expansion nozzle 153 with an increased cross section, the velocity of the exhaust gas decreases. Therefore, when the exhaust gas passes through the intake cone 4, the exhaust gas tends to diffuse in a direction orthogonal to the main flow. This results in a uniform velocity distribution of the exhaust gas flowing into the housing 21 of the exhaust gas purifier 2, thereby improving the exhaust gas purifying performance. In addition, the uniform velocity distribution reduces the resistance of exhaust gas, which is advantageous in improving fuel efficiency.

The conical portion 41 connects the straight portion 42 having a small cross-sectional area to the housing 21 having a large cross-sectional area. The conical portion 41 includes an inclined wall that is inclined from the main flow of the exhaust gas to increase the cross section of the exhaust gas path. The conical portion 41 comprises four

inclined walls

411, 412, 413 and 414 to connect a straight portion 42 with a circular cross section to the housing 21 with a flat cross section. The four inclined walls include two

inclined walls

411 and 412 corresponding to a pair of long sides of the housing 21, and two

inclined walls

413 and 414 corresponding to a pair of short sides of the housing 21. Referring to the drawing, the boundaries between the four sloped

walls

411, 412, 413, 414 and 414 are actually represented by a two-point chain. The two inclined walls corresponding to the pair of long sides are a right inclined wall 411 and a left inclined wall 412. The two inclined walls corresponding to a pair of short sides are an upper inclined wall 413 and a lower inclined wall 414. The inclined wall 411 has the same shape as the left inclined wall 412. As described above, the straight portion 42 moves upward from the center of the housing 21. In other words, the location of the turbine 151 that connects to the conical outlet. The portion 41 moves upward. Therefore, the upper inclined wall 413 has a different shape from the lower inclined wall 414. The two inclined walls corresponding to a pair of short sides are an upper inclined wall 413 and a lower inclined wall 414. The right inclined wall 411 has the same shape as the left inclined wall 412. As described above, the straight portion 42 moves upward from the center of the housing 21. In other words, the position of the outlet of the turbine 151 connected to the conical portion 41 is moved upward. Therefore, the upper inclined wall 413 has a different shape from the lower inclined wall 414. The two inclined walls corresponding to a pair of short sides are an upper inclined wall 413 and a lower inclined wall 414. The right inclined wall 411 has the same shape as the left inclined wall 412. As described above, the straight portion 42 moves upward from the center of the housing 21. In other words, the position of the outlet of the turbine 151 connected to the conical portion 41 is moved upward. Therefore, the upper inclined wall 413 has a different shape from the lower inclined wall 414. The position of the outlet of the turbine 151 connected to the conical portion 41 moves upward. Therefore, the upper inclined wall 413 has a different shape from the lower inclined wall 414. The position of the outlet of the turbine 151 connected to the conical portion 41 moves upward. Therefore, the upper inclined wall 413 has a different shape from the lower inclined wall 414.

The left and right

inclined walls

411 and 412 of the tapered portion 41 have

grooves

43 and 44, respectively. Each of the

recesses

43 and 44 is recessed toward the inside of the conical portion 41. The recess 43 includes a first wall 431 and a second wall 432. The recess 44 includes a first wall 441 and a second wall 442. The

first walls

431 and 441 expand along the main flow and long sides of the exhaust. The

second walls

432 and 442 are continuous with the

first walls

431 and 441 and respectively expand outward from the

first walls

431 and 441 along the long sides.

The recess of the right inclined wall 411 has a different size from the recess of the left inclined wall 412. Specifically, the second notch 44 of the left inclined wall 412 is larger than the first notch 43 of the right inclined wall 411. A large depression here means that the

depression

43 or 44 has a large inward depth. Due to the deeper grooves, first wall 441 of second groove 44 is longer than first wall 431 of first groove 43, and second wall 442 of second groove 44 is longer than second wall 432 of first groove 43.

The vortex flow from the turbine 151 rotates counterclockwise when viewed from the front of the exhaust gas cleaner 2. The exhaust gas coming out from the inlet of the conical portion 41 passes through the right long side to the upper short side in the direction of the swirling flow. The exhaust gas from the inlet of the conical portion 41 passes through the left long side in the direction of the swirling flow to the lower short side. The exhaust gas purifier 2 is connected directly downstream of the outlet of the turbine 151. At high speed of the turbine 151, the exhaust gas is strongly swirled to flow into the housing 21 via the intake cone 4. Directing the exhaust gases outwardly. In a housing 21 with a flat cross-section, the long side parts are closer to the entrance of the entrance cone 4 than the short side parts. Therefore, the flow volume of the exhaust gas at the long side portion will be higher than that at the short side portion. However, in the exhaust gas purifier 2 configured as described above, the first inner concave portion 43 and the second inner concave portion 44 are formed on the left and right

inclined walls

411 and 412 corresponding to the pair of long sides. Inside the inlet cone 4, the flow of exhaust gas to the peripheral area is limited by the first and

second grooves

43 and 44. The exhaust gas flows along the

first walls

431 and 441 of the first and

second grooves

43 and 44. The flow changes from long to short sides. This reduces the biased velocity distribution of the exhaust gas flowing into the housing 21 having a flat cross section when the exhaust gas strongly swirls. As a result, the exhaust gas purifier 2 maintains high purification performance. In addition, the first recess 43 and the second recess 44 reduce an increase in the flow volume of the exhaust gas at the long side portion of the housing 21 having a flat cross section. This results in a reduction of thermal damage at the long sides. As a result, the reliability of the exhaust gas purifier 2 is improved.

In the above configuration, the straight portion 42 of the intake cone 4 moves upward from the center of the conical portion 41 to be connected to the conical portion 41. The second concave portion 44 of the left inclined wall 412 is formed to be large according to the moving direction and the swirling direction of the exhaust gas. When the exhaust gas is strongly swirling, the second recess 44 strictly restricts the flow of the exhaust gas to the peripheral area, thereby orienting the exhaust gas toward the lower short side farther from the inlet of the intake cone 4.

On the other hand, the small first recess 43 of the right sloping wall 411 restricts the flowing exhaust gas less tightly, so that the exhaust gas is directed towards the upper short side closer to the inlet of the inlet cone 4.

This results in a uniform velocity distribution of the exhaust gas flowing into the housing 21 even in the exhaust gas purifier 2 in which the straight portion 42 is connected with the conical portion 41 at an off-center position.

Simulations relating to the shape of the inlet cone will now be described with reference to the drawings. As a modeled inlet cone 40, the straight portion is not shown, but only the conical portion 402 is shown. The expansion nozzle 153 at the outlet of the turbine 151 is directly connected to the conical section 402. An expansion nozzle 153 is connected to the center of the conical section 402. Exhaust flow in expansion nozzle 153 and conical section 402. The swirling flow discharged from the turbine 151 rotates clockwise when viewed from the front of the exhaust purifier 2. This is in contrast to the above described embodiment.

Specifically, the case where the outlet of the turbine 151 is not the expansion nozzle 153 but the straight nozzle 154 is compared with the case where the outlet of the turbine 151 is the expansion nozzle 153. Reference numerals 1001 and 1004 denote the shape of the inlet cone. Reference numerals 1002 and 1005 denote contours of velocity distribution in the main flow direction of the exhaust gas at the outlet of the conical portion 402. Reference numerals 1003 and 1006 denote the direction of the exhaust gas on a cross-section through the central axis of the inlet cone. Reference numerals 1101 and 1104 denote the shapes of the inlet cones. Reference numerals 1102 and 1105 denote constant velocity lines indicating the velocity distribution in the main flow direction of the exhaust gas at the outlet of the conical portion 402. Reference numerals 1003 and 1006 denote the directions of the exhaust gas flowing on a cross section passing through the center axis of the intake cone.

In weak vortices, the axial velocity component of the inlet cone increases. As indicated by reference numeral 1003, the exhaust gas flowing into the conical portion 402 through the straight nozzle 154 is less diffused in the conical portion 402. The exhaust gas enters directly into the housing 21 of the exhaust gas purifier. As indicated by reference numeral 1002, the velocity of the exhaust gas is relatively high in the central region of the outlet of the conical portion 402 and relatively low in the peripheral region.

In contrast, in the structure having the expansion nozzle 153, the velocity of the exhaust gas decreases as it passes through the expansion nozzle 153. In the expansion nozzle 153, the exhaust gas starts to diffuse. Therefore, as indicated by reference numeral 1006, the exhaust gas easily diffuses. At the outlet of the conical section 402, the velocity distribution of the exhaust gas is more uniform than in the case of the straight nozzle 154, as indicated by reference numeral 1005. The velocity distribution of the exhaust gas flowing into the housing 21 is uniform. The exhaust gas purification performance by the catalytic converter is improved. In addition, the uniform velocity distribution reduces the resistance of exhaust gas, thereby improving fuel efficiency.

Under strong swirl, the exhaust gas flows to the surrounding area due to centrifugal force. In the straight nozzle 154, the exhaust gas tends to flow toward the peripheral region of the nozzle. As indicated by reference numeral 1003, in the portion of the straight nozzle 154 connected to the conical portion 402, the exhaust gas flows along the inner peripheral surface of the conical portion 402. In this manner, as indicated by reference numeral 1102, at the exit of the conical portion 402, the velocity of the exhaust gas is higher in the peripheral region. In strong swirl, the exhaust gas flows to the peripheral region due to centrifugal force, and the velocity component in the axial direction of the inlet cone is reduced. Thus, at the exit of the conical portion 402, the velocity of the exhaust gas is lower at the center portion. The velocity distribution of the exhaust gas flowing into the housing 21 becomes uneven.

In contrast, in the structure having the expansion nozzle 153, the velocity of the exhaust gas decreases as it passes through the expansion nozzle 153. This reduces the exhaust gas concentration toward the peripheral area of the nozzle. This results in a reduction in the exhaust gas flowing along the inner circumferential surface of the conical portion 402 at the portion of the expansion nozzle 153 that connects with the conical portion 402, as indicated by reference numeral 1106. The exhaust gas diffuses in the conical section 402. At the exit of the conical section 402, the velocity profile of the exhaust gas is more uniform than in the case of the straight nozzle 154, as indicated by reference number 1105.

In this way, the expansion nozzle 153 disposed upstream of the conical portion 402 makes the velocity distribution of the exhaust gas flowing into the housing 21 of the exhaust gas purifier 2 uniform in the case where the exhaust gas weakly swirls strongly. The exhaust gas flowing at the concave tapered portion will now be considered. Reference numeral 1105 indicates that when the exhaust gas strongly swirls, the velocity of the exhaust gas increases in a portion corresponding to the long side of the housing 21, the cross section of which is flat, the cross section including a pair of short sides and a pair of long sides. If the exhaust gas passing through the exhaust gas purifier has a biased velocity distribution, the exhaust gas purification performance may be degraded. The strong swirl of the exhaust gas corresponds to a higher turbine speed. An increase in the flow volume of the exhaust gas in the portion corresponding to the long side may cause an excessive temperature increase at that specific portion, which leads to thermal damage.

Thus, although the expansion nozzle 153 disposed upstream of the conical portion 402 makes the velocity distribution of the exhaust gas relatively uniform, improvements are still needed.

An inward recess 403 is formed in the tapered portion 402, and a recess 403 is provided in each of the right and left inclined walls of the tapered portion 402. The recess 403 of the right sloping wall has the same shape as the recess 403 of the left sloping wall. Like the previously described dimples, each dimple 403 expands along the main flow of exhaust gas and includes a first wall 4031 and a second wall 4032. The first wall 4031 extends along a long side. The second wall 4032 is continuous with the first wall 4031 and extends outwardly from the first wall 4301 along the long edges.

As mentioned above, the strong swirl of the exhaust gas causes centrifugal forces which orient the exhaust gas towards the peripheral region. The first wall 4031 of the recess 403 interferes with the exhaust gas flowing from the expansion nozzle 153 into the conical portion 402 and flowing toward the peripheral edge region of the long side portion, and orients the exhaust gas in the direction from the long side to the short side. Along the sides of the first wall 4031. This restricts the exhaust gas flowing from the inlet of the conical portion 402 to the portion corresponding to the long side. The recesses 403 reduce the velocity at the long side portions but increase the velocity at the short side portions. Since the short side portion is farther from the inlet of the conical portion 402, the flow rate of the exhaust gas tends to decrease. However, if the conical portion 402 has the concave portion 403, the flow rate of the exhaust gas flowing through the short side portion increases.

In this way, the recess 403 of the conical portion 402 makes the velocity distribution of the exhaust gas passing through the housing 21 of the exhaust purifier 2 having a flat cross section more uniform. As a result, the purification performance of the exhaust gas is improved, and the thermal damage in the portion corresponding to the long side is reduced.

Reference numeral 1203 is labeled "1". 12 denotes an inlet cone 40 configured to further accelerate the exhaust gas flowing from the long side to the short side. The inlet cone 40 includes a downstream notch 405 adjacent to the notch 403 along a long side. The downstream recess 405 is located downstream of the recess 403 in the direction of the exhaust swirl. The downstream recess 405 includes a first wall 4051 and a second wall 4052. The first wall 4051 expands along the main flow of exhaust gas and along the long side. The second wall 4052 is continuous with the first wall 4051 and extends outwardly from the first wall 4501 along the long sides. The downstream recess 405 is recessed deeper than the recess 403. Since the downstream concave portion 405 is provided downstream of the concave portion 403 in the swirling direction, the exhaust gas flowing from the long side to the short side is further accelerated. A comparison between reference numbers 1202 and 1204 makes it clear that: a portion of the portions corresponding to the short sides, in which the exhaust gas velocity is relatively high, is moved to a downstream position in the direction by the downstream concave portion 405. And (4) exhausting the vortex. In this way, the combination of the recess 403 and the downstream recess 405 controls the position of the region having a high exhaust gas velocity in the exhaust gas purifier 2 having a flat cross section. The exhaust gas is diffused in the conical portion 402 to make the velocity distribution of the exhaust gas flowing into the housing 21 uniform. As a result, the exhaust gas purifier 2 maintains high purification performance of the exhaust gas, and suffers less thermal damage in some parts.

The recesses 403 provided in the conical portion 402 restrict the exhaust gas flowing from the inlet of the conical portion 402 to the peripheral area of the long side when the exhaust gas strongly swirls and orient the exhaust gas in the direction from the long side. Short side. The larger the recess 403 is, the more the exhaust gas flowing from the long side to the short side is promoted.

In view of the direction in which the exhaust gas swirls, in a preferred embodiment the notch in the right sloping wall is larger to orient the exhaust gas from the long side towards the short side and to speed up the flow. On the other hand, in a preferred embodiment, the recess in the left sloping wall is smaller.

In short, a first recess is formed on the left long side, through which the exhaust gas passes from the inlet of the conical portion 402 in the direction of the exhaust gas vortex to the upper short side. A second recess is formed on the right long side through which exhaust gas passes from the inlet of the conical portion 402 in the direction of the vortex. In the preferred embodiment, the second recess is larger than the first recess.

If the intake port of the intake port cone 4 is moved vertically, a difference in size between the left and right concave portions sandwiching the intake port therebetween results in a velocity distribution of the exhaust gas flowing into the housing 21 of the exhaust gas purifier 2.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An engine exhaust structure comprising: a turbine of a turbocharger that is provided for an exhaust pipe of an engine and that is rotated by exhaust energy of the engine; and an exhaust gas purifier directly connected to a downstream side of the turbine for purifying exhaust gas, characterized in that: the exhaust gas purifier includes a housing having a flattened cross-section with a pair of opposing short sides and a pair of opposing long sides and configured to house a catalytic converter, an inlet cone including a conical portion and configured to connect an outlet of the turbine to an inlet of the housing, the conical portion including an inclined wall inclined from a main flow of the exhaust gas to increase a portion of a lateral exhaust gas path.

2. The engine exhaust structure according to claim 1, characterized in that: the recess includes: a first wall extending along a main flow of the exhaust gas and along the opposite long sides; and a second wall continuous with and extending outwardly from the first wall along the first wall.

3. The engine exhaust structure according to claim 1, characterized in that: an expansion is provided between the outlet of the turbine and the inlet of the inlet cone, and the cross section of the exhaust path gradually increases in the expansion.

4. The engine exhaust structure according to claim 1, characterized in that: the position of the outlet of the turbine connected to the conical portion is offset toward one of the facing short sides, i.e., the inlet of the intake port, in the direction in which the facing short sides face each other; inserting a conical portion between the opposing long sides, forming a first recess in a portion of one of the opposing long sides, through which exhaust gas from the inlet of the conical portion passes in a direction in which the exhaust gas swirls, thereby reaching one of the opposing short sides, and forming a second recess in a portion of the other of the opposing long sides, along which exhaust gas from the inlet of the conical portion passes, the gas swirls, reaching the other opposing short side, wherein the second recess is larger than the first recess.

5. The engine exhaust structure according to claim 1, characterized in that: the concave portion is composed of an upstream concave portion and a lower concave portion, and the upstream concave portion is positioned upstream of the exhaust gas in the direction in which the exhaust gas rotates along the opposite long sides; the downstream concave portion is located downstream of the direction in which the exhaust gas rotates along the opposite long sides; the downstream groove is deeper than the upstream groove.

6. The engine exhaust structure according to claim 1, characterized in that: an engine compartment including the engine includes the exhaust purifier and a second exhaust purifier connected downstream of the exhaust purifier.

7. The engine exhaust structure according to claim 1, characterized in that: the engine is longitudinally installed, the housing of the exhaust purifier has a vertically long flat cross section, the exhaust purifier is placed at one side of the engine, and the engine and the exhaust purifier are surrounded and encapsulated by a partition.

8. The engine exhaust structure according to claim 7, characterized in that: the turbine is placed over an exhaust manifold of the engine, the exhaust purifier is placed near a top of the engine, and an insulating wall covering the engine and the exhaust purifier is placed over the exhaust purifier.