JP5428786B2 - Exhaust gas recirculation device - Google Patents

Description

  The present invention relates to a technology of an exhaust gas recirculation device that introduces EGR gas into an intake system.

  Conventionally, an exhaust gas recirculation device that returns part of exhaust gas to an intake system has been proposed in order to improve fuel consumption and reduce NOx in a low load region of the engine. The exhaust gas recirculation device includes a circulation passage that guides exhaust gas to the intake system. The circulation passage is connected to an intake passage through which fresh air flows in the intake system.

  Fresh air and EGR gas are mixed at the connection portion between the intake passage and the circulation passage. And the air-fuel mixture of fresh air and EGR gas flows downstream from the connecting portion. The connection structure between the intake passage and the circulation passage will be described in detail. The intake pipe constituting the intake passage and the circulation passage pipe constituting the circulation passage are connected to each other. The circulation passage pipe is connected so as to abut against the intake pipe from the side. Therefore, the EGR gas supplied from the circulation passage is supplied from one side of the intake pipe.

  As a result, the EGR gas does not easily spread in the intake passage in the downstream region immediately after the connecting portion. Since the EGR gas hardly spreads in the intake passage, fresh air and EGR gas are separated in the intake passage. Therefore, the gas flowing in the intake passage immediately downstream of the connecting portion. The flow velocity distribution of (the mixture of fresh air and EGR gas) is not uniform within the same flow path cross section.

  For example, if the connection portion between the intake passage and the circulation passage is arranged immediately upstream of the turbocharger compressor, the flow velocity distribution is not uniform in the cross section of the flow channel immediately downstream of the connection portion as described above. The pressure acting on the compressor (pressure caused by the mixture of fresh air and EGR gas) varies depending on the part.

  As a result, a force in a direction crossing the rotation axis of the compressor acts on the compressor, so that the compressor and the housing housing the compressor come into contact with each other, wear due to the contact, and between the rotation shaft and the bearing. It is conceivable that the compressor is damaged due to wear.

  For this reason, even immediately downstream of the connection portion between the circulation passage and the intake passage, the EGR gas diffuses and the flow velocity distribution in the passage cross section becomes uniform so that the fresh air flows around the intake passage. A technique has been proposed in which an annular passage is formed so as to surround the intake passage, and EGR gas is introduced from the circumferential direction into the intake passage through the annular passage.

  In this type of technology, a hole is formed between the intake passage and the annular passage, and the intake passage and the annular passage communicate with each other through the hole. The circulation path is connected to the annular path, and EGR gas is guided. The EGR gas guided to the annular passage is introduced from the circumferential direction into the intake passage through the hole (for example, see Patent Document 1).

  In addition, a flow path in which the EGR gas flows along the circumferential direction of the intake passage is formed outside the intake passage, and the EGR gas after flowing in the flow path is tangential to the intake passage with respect to the intake passage. The technology to introduce along is proposed. A communication hole is formed between the flow path through which the EGR gas flows and the intake passage, and the EGR gas is also introduced into the intake passage through the communication hole (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 3-114564 JP 2000-161147 A

  However, as in Patent Documents 1 and 2, a flow path in which EGR gas flows along the circumferential direction of the intake passage is formed outside the intake passage, and a constant diameter formed between the flow passage and the intake passage. When the EGR gas is introduced into the intake passage through the holes, when the flow rate of the EGR gas is small, the amount of EGR gas introduced into the intake passage from each hole becomes uneven depending on the location of the holes, and the fresh air and the EGR gas are uniform. It may be difficult to mix with each other. Further, when the EGR gas flow rate is large, the flow of the EGR gas is hindered, so that the EGR gas suction resistance increases. As a result, it is conceivable that EGR gas is hardly introduced into the intake passage.

  The present invention efficiently introduces exhaust gas into the intake passage and suppresses non-uniform flow velocity distribution in the cross section of the intake passage even immediately downstream of the connection portion between the intake passage and the circulation passage. An object of the present invention is to provide an exhaust gas recirculation device that can be used.

The exhaust gas recirculation device according to claim 1 of the present application is formed in an annular shape extending along the circumferential direction of the intake passage, an intake passage through which intake air flows, a main flow passage that is a part of the intake passage, and the intake passage. An annular passage that surrounds the intake passage and is formed around the main passage and communicates with the main passage, and extends in a circumferential direction of the intake passage between the intake passage and the annular passage. An annular inlet that communicates the intake passage and the annular flow path, communicates with the annular flow path, and guides exhaust gas into the annular flow path so as to flow in one direction of the circumferential direction. And an exhaust gas introduction path. The exhaust gas introduction passage, Ru is connected to the annular flow path in the not overlapping the main channel located in the direction of flow from the exhaust gas introduction passage of exhaust gases upon flowing into the annular flow path. In the annular channel, a regulation wall portion is provided at a position facing the connecting portion between the annular channel and the exhaust gas introduction path with a gap therebetween. A cooling pipe is provided in the regulation wall, and the refrigerant flows in the cooling pipe.

  The exhaust gas recirculation device according to the second aspect of the present invention is the exhaust gas recirculation device according to the first aspect, wherein the regulation wall portion has a crescent shape that is concave toward the inflow port.

The exhaust gas recirculation device according to claim 3 of the present application is the exhaust gas recirculation device according to claim 1 or 2 , wherein the inside of the annular flow path forming the upstream opening edge of the intake passage of the inflow port. The angle formed by the inner wall surface of the annular flow path that forms the downstream opening edge of the intake passage and the inner wall surface of the intake passage is larger than the angle formed by the wall surface and the inner wall surface of the intake passage. did.

An exhaust gas recirculation device according to a fourth aspect of the present invention is the exhaust gas recirculation device according to any one of the first to third aspects, wherein the intake air is provided on the upstream opening edge side of the intake passage of the inflow port. A throttle portion for reducing the channel cross-sectional area of the passage was formed.

The exhaust gas recirculation device according to claim 5 of the present application is the exhaust gas recirculation device according to any one of claims 1 to 4 , wherein the inlet and The width of the opposed bottom edges decreases continuously as it proceeds downstream along the one direction.
In the exhaust gas recirculation device according to the sixth aspect of the present invention, in the exhaust gas recirculation device according to any one of the first to fifth aspects, a direction in which the exhaust gas flows in the circumferential direction is the intake air. This is the same direction as the rotation direction of the compressor provided in the passage.

  According to the present invention, while exhaust gas is efficiently introduced into the intake passage, the exhaust gas is uniformly introduced from the circumferential direction of the intake passage, and the flow passage is also immediately downstream of the connection portion between the intake passage and the circulation passage. The non-uniform flow velocity distribution in the cross section is suppressed.

1 is a schematic diagram showing an engine system including an exhaust gas recirculation device according to a first embodiment of the present invention. FIG. 2 is a perspective view showing the connection portion shown in FIG. 1 and a portion of the intake system in the vicinity of the connection portion with a part cut away. Sectional drawing of the site | part of the connection part shown along the F3-F3 line shown in FIG. 2, and the vicinity of a connection part in an intake system. FIG. 4 is a perspective view showing a connection portion that is sectioned as shown in FIG. 3 and a portion of the intake system in the vicinity of the connection portion that is partially cut away. Sectional drawing of the connection part shown along F5-F5 line shown in FIG. FIG. 2 is a side view showing a state in which the vicinity of a throttle valve is viewed from the side in the intake passage shown in FIG. Sectional drawing which shows the state which cut | disconnected the connection part of the exhaust gas recirculation apparatus which concerns on the 2nd Embodiment of this invention similarly to FIG. 5 of 1st Embodiment. Sectional drawing which shows the state which cut | disconnected the connection part of the exhaust gas recirculation apparatus which concerns on the 3rd Embodiment of this invention similarly to FIG. 5 of 1st Embodiment. Sectional drawing which shows the state which cut | disconnected the connection part of the exhaust gas recirculation apparatus which concerns on the 4th Embodiment of this invention similarly to FIG. 3 of 1st Embodiment. The perspective view which shows the state which looked at the connection part shown by FIG. 9 from the cross section similarly to FIG. 4 of 1st Embodiment. Schematic which shows the flow-path cross section of the annular flow path shown by FIG.

  An exhaust gas recirculation apparatus according to a first embodiment of the present invention will be described with reference to FIGS. The exhaust gas recirculation apparatus of this embodiment is used for an engine system 10 including a diesel engine 11 as an example. The engine system 10 is mounted on, for example, an automobile (not shown).

  FIG. 1 is a schematic diagram showing an engine system 10. As shown in FIG. 1, an engine system 10 includes a reciprocating diesel engine 11, an intake system 20 that guides intake air to the diesel engine 11, and an exhaust system 30 that guides exhaust gas discharged from the diesel engine 11 to the outside of the automobile. And a turbocharger 70.

  In this embodiment, the diesel engine 11 includes a cylinder block 12 and a cylinder head 13. The diesel engine 11 is discharged from an intake passage (a part of the intake system 20) that guides intake air into the cylinder 14 or from the cylinder 14. The exhaust passage (a part of the exhaust system 30) that guides the exhaust gas to the outside is a portion that is excluded.

  The intake system 20 includes an air cleaner 21, an intercooler 22, a throttle valve 24, the air cleaner 21, the intercooler 22, the cylinder 14, and an intake passage 23 that guides intake air to the cylinder 14. The air cleaner 21 is disposed upstream of the intake passage 23 and communicates with the intake passage 23. The air (fresh air) that has passed through the air cleaner 21 is guided into the intake passage 23 and is guided to the diesel engine 11. The intercooler 22 is disposed downstream of the air cleaner 21 in the intake passage 23.

  A compressor 71 (shown in FIG. 3) of the turbocharger 70 is provided between the air cleaner 21 and the intercooler 22 in the intake passage 23. The throttle valve 24 is provided between the air cleaner 21 and the compressor 71 in the intake passage 23. The intake passage 23 is formed by a pipe member 25, for example.

  The exhaust system 30 includes an exhaust passage 31, a catalyst 32, a filter 33, a high pressure EGR (Exhaust Gas Recirculation) device 40, a low pressure EGR device 50, and the like. The exhaust passage 31 communicates with each cylinder 14 of the diesel engine 11 and guides the exhaust gas G exhausted from each cylinder 14 to the outside. The turbine 72 of the turbocharger 70 is provided in the exhaust passage 31.

  The catalyst 32 and the filter 33 are provided in the exhaust passage 31 and are disposed downstream of the turbine 72. The catalyst 32 is an oxidation catalyst, for example, and oxidizes HC and CO in the exhaust gas G. The filter 33 is disposed downstream of the catalyst 32. The filter 33 collects the particulate matter in the exhaust gas G.

  The exhaust passage 31 is formed by a pipe member 34, for example. The pipe member 34 connects each device provided in the exhaust system 30 such as the turbine 72, the catalyst 32, and the filter 33, and guides the exhaust gas G to the outside.

  The high pressure EGR device 40 includes a high pressure EGR circulation passage 41, a high pressure EGR catalyst 42, and a high pressure EGR valve 43. The high-pressure EGR circulation passage 41 connects and communicates a position upstream of the turbine 72 in the exhaust passage 31 and a position downstream of the intercooler 22 in the intake passage 23.

  The high pressure EGR catalyst 42 is provided in the high pressure EGR circulation passage 41. The high pressure EGR catalyst 42 collects deposits in the exhaust gas G flowing into the high pressure EGR circulation passage 41.

  The high pressure EGR valve 43 is provided at a connecting portion between the high pressure EGR circulation passage 41 and the intake passage 23, and can open and close the high pressure EGR introduction port 44 that connects the high pressure EGR circulation passage 41 and the intake passage 23. Block. The high-pressure EGR valve 43 is controlled by, for example, a control unit (not shown), and the opening / closing and opening degree are adjusted according to the required amount of EGR gas.

  The low pressure EGR device 50 is an example of the exhaust gas recirculation device of the present application. The low pressure EGR device 50 includes a low pressure EGR circulation passage 51, an EGR cooler 52, and a low pressure EGR valve 400. The low pressure EGR circulation passage 51 is connected to a position downstream of the filter 33 in the exhaust passage 31 and a position between the throttle valve 24 and the compressor 71 in the intake passage 23. Is communicated. The EGR cooler 52 is provided in the low pressure EGR circulation passage 51.

  The low-pressure EGR valve 400 is disposed downstream of the EGR cooler 52 in the low-pressure EGR circulation passage 51 and opens and closes the low-pressure EGR circulation passage 51 (in this embodiment, an exhaust gas introduction passage 80 described later). . When the low-pressure EGR valve 400 is opened, the low-pressure EGR circulation passage 51 is opened, so that the exhaust gas G is guided to the intake passage 23. When the low-pressure EGR valve 400 is closed, the low-pressure EGR circulation passage 51 is closed, so that the exhaust gas G is not guided to the intake passage 23.

  The low-pressure EGR circulation passage 51 includes a connecting portion 60 connected to the intake passage 23 and an exhaust gas introduction passage 80 connected to the exhaust passage 31 to guide the exhaust gas G to the connecting portion 60.

  A range F <b> 1 surrounded by a two-dot chain line in FIG. 1 indicates the connection portion 60 and a portion in the vicinity of the connection portion 60 in the intake system 20. FIG. 2 is a perspective view showing a part of the connection part 60 and the vicinity of the connection part 60 in the intake system 20.

  As shown in FIGS. 1 and 2, the connecting portion 60 is connected between the throttle valve 24 and the compressor 71 in the intake passage 23. FIG. 3 is a cross-sectional view of the connecting portion 60 shown along the line F3-F3 shown in FIG. 2 and a portion in the vicinity of the connecting portion 60 in the intake system 20. FIG. 4 is a perspective view showing the connecting portion 60 cross-sectioned as shown in FIG. 3 and a portion in the vicinity of the connecting portion 60 in the intake system 20. FIG. 5 is a cross-sectional view of connecting portion 60 shown along line F5-F5 shown in FIG.

  As shown in FIGS. 2 to 4, the connecting portion 60 surrounds the intake passage 23 on the inner side in the circumferential direction. The connecting portion 60 includes a main channel 61 that is a part of the intake passage 23 and an annular channel 62 that is formed around the main channel 61 and communicates with the main channel 61. The main channel 61 is an example of the main channel referred to in the present invention.

  As shown in FIG. 5, the annular channel 62 is formed along the circumferential direction of the main channel 61 so as to surround the main channel 61 inside. The annular channel 62 is formed in an annular shape along the circumferential direction A of the main channel 61. The circumferential direction is indicated by an arrow in the figure. In FIG. 5, an edge 27a that defines the inflow port 63 is shown. The annular channel 62 is an example of the annular channel referred to in the present invention.

  An inflow port 63 is formed between the main channel 61 and the annular channel 62. The main channel 61 and the annular channel 62 communicate with each other through the inlet 63. The inflow port 63 is formed in an annular shape along the circumferential direction A of the main flow path 61. That is, the inflow port 63 is formed in the entire circumferential direction of the main channel 61. For this reason, the main channel 61 and the annular channel 62 communicate with each other in the circumferential direction A of the main channel 61, and the main channel 61 and the annular channel 62 communicate with each other in the entire circumferential direction of the main channel 61. doing. The inflow port 63 is an example of the inflow port referred to in the present invention.

  The annular channel 62 will be specifically described. As shown in FIG. 3, the annular flow path 62 is defined by the inner surface of the outer peripheral wall portion 64. The outer peripheral wall portion 64 includes a bottom wall portion 65 that faces the inflow port 63, an upstream side wall portion 66 that faces the upstream side of the main channel 61, and a downstream side wall portion 67 that faces the downstream side of the main channel 61. Have. The bottom wall portion 65 is formed in a gentle annular shape along the circumferential direction A of the main channel 61 so as to surround the main channel 61 inside.

  The upstream side wall portion 66 is connected to the upstream edge of the bottom wall portion 65 and is integrated. Further, the upstream side wall portion 66 is connected to the edge 26 a of the first communication port 26 that is located upstream of the main flow path 61 in the intake passage 23 and communicates with the main flow path 61. Further, the intake passage 23 immediately upstream from the edge 26 a is connected to the edge 26 a by forming a throttle portion 110 so that the flow passage cross-sectional area becomes smaller toward the center of the cross section of the intake passage 23. The downstream side wall 67 is connected to the downstream edge of the bottom wall 65. Further, the downstream side wall 67 is connected to the edge 27 a of the second communication port 27 that is located downstream of the main channel 61 in the intake passage 23 and communicates with the main channel 61.

  As described above, the inflow port 63 is defined by the connecting portion between the upper and lower side wall portions of the outer peripheral wall portion 64 that defines the annular flow path 62 and the intake passage.

  The exhaust gas introduction path 80 is connected to the annular flow path 62 so that the exhaust gas G flows in one direction A <b> 1 of the circumferential direction A in the annular flow path 62. The one direction A <b> 1 is the same direction as the rotation direction of the compressor 71. The one direction A1 is an example of one direction referred to in the present invention. FIG. 5 shows a state in which the annular channel 62 is cross-sectioned so as to cross the axial center line 61a of the main channel 61 vertically. As shown in FIG. 5, the exhaust gas introduction path 80 is connected to the annular flow path 62 along the tangential direction of the outer peripheral edge 62 a of the annular flow path 62 defined by the inner surface of the bottom wall portion 65. The exhaust gas introduction path 80 is connected to a position that does not overlap the main flow path 61 in the direction B in which the exhaust gas G flows when flowing into the annular flow path 62 from the exhaust gas introduction path 80.

  In the drawing, the direction B in which the exhaust gas G flows when it flows into the annular flow path 62 from the exhaust gas introduction path 80 is indicated by an arrow. Further, in the figure, a range overlapping with the main flow channel 61 when viewed along the direction B is indicated by a range 103 surrounded by a pair of two-dot chain lines 101 and 102, and a range not overlapping is indicated by reference numerals 100 and 104. . A range 100 is a range on the right side of the two-dot chain line 101 in the figure. A range 104 is a range on the left side of the two-dot chain line 102 in the figure. Thus, the exhaust gas G is connected within the range 100.

  As the exhaust gas introduction path 80 is connected to the annular flow path 62 as described above, the exhaust gas G introduced into the annular flow path 62 from the exhaust gas introduction path 80 is indicated by an arrow in the figure. , And flows along one direction A1 in the circumferential direction A. The exhaust gas introduction path 80 is an example of the exhaust gas introduction path referred to in the present invention.

  The above-described connection structure of the exhaust gas introduction path 80 is an example. The connection structure between the exhaust gas introduction path 80 and the annular flow path 62 may be different from the above. In short, in the exhaust gas introduction path 80, the exhaust gas introduced from the exhaust gas introduction path 80 into the annular flow path 62 may flow along the one direction A1 in the circumferential direction A in the annular flow path 62. .

  Next, the width w1 of the inflow port 63 and the width w2 of the inner surface 65a of the bottom wall portion 65 will be described. As shown in FIG. 3, the width w <b> 1 here indicates the length of the opening of the inflow port 63 along the axial center line 61 a of the main flow path 61. In the present embodiment, the axial center line 23a of the intake passage 23 and the axial center line 61a of the main flow path 61 overlap each other, and are therefore the same. The width w2 of the inner surface 65a of the bottom wall portion 65 referred to here is a length that is so long as the axial center line 61a of the main channel 61 on the inner surface 65a. The inner surface 65a is an example of a bottom edge referred to in the present invention. w2 is the width of the bottom edge referred to in the present invention.

  As shown in FIG. 3, in the present embodiment, the width w <b> 1 of the inflow port 63 is kept constant in an annular shape in the circumferential direction of the main flow path 61. In the present embodiment, the width w <b> 2 of the inner surface 65 a of the bottom wall portion 65 is kept constant in an annular shape in the circumferential direction A of the main channel 61. In the present embodiment, the width w1 of the inflow port 63 and the width w2 of the inner surface 65a of the bottom wall portion 65 are the same length.

  In the present embodiment, the width w3, which is the distance between the inflow port 63 and the inner surface 65a, continuously decreases as it proceeds downstream along the one direction A1. For this reason, the area of the cross section of the flow path crossing the one direction A1 of the annular flow path 62 continuously decreases as the flow proceeds downstream along the one direction A1.

  The annular channel 62 is defined by inner surfaces 65 a, 66 a, 67 a of the bottom wall portion 65, the upstream side wall portion 66, and the downstream side wall portion 67. As shown in FIG. 3, the inner surface 67 a of the downstream side wall portion 67 is planar. The angle α defined by the inner surface 67 a of the downstream side wall 67 and the inner surface 25 a of the pipe member 25 that defines the intake passage 23 is 90 degrees over the entire circumference in the circumferential direction A of the main channel 61. The inner surface 67a of the downstream side wall portion 67 is an example of the downstream side edge referred to in the present invention. A connecting portion 90 between the inner surface 67a of the downstream side wall 67 and the inner surface 25a of the pipe member 25 constituting the intake passage 23 is gently formed from the inner surface 67a to the inner surface 25a. The angle α is an angle defined by the present invention between the inner wall surface of the annular flow path that forms the downstream opening edge of the intake passage at the inlet and the inner wall surface of the intake passage.

  Further, the inner surface 66a of the upstream side wall portion 66 is planar. The angle θ defined by the inner surface 66a of the upstream side wall portion 66 and the inner surface 25a of the pipe member 25 that defines the intake passage 23 is smaller than the angle α over the entire circumference in the circumferential direction A of the main flow path 61. In the present embodiment, since the angle α is 90 degrees, the angle θ is an acute angle. The angle θ is an angle defined by the present invention between the inner wall surface of the annular flow path that forms the upstream opening edge of the intake passage at the inlet and the inner wall surface of the intake passage.

  More specifically, since the throttle portion 110 described later is formed in the intake passage 23, the connecting portion between the inner surface 25a and the inner surface 66a of the intake passage 23 protrudes toward the axial center line 23a side of the intake passage 23. The protruding portion 500 is formed. The tip of the protrusion 500 is an edge 26a. A part of the inner surface 66 a constitutes a protruding portion 500. A part of the inner surface 25 a constitutes a part of the protruding portion 500. The angle θ is defined by the portion constituting the inner surface 66a in the protruding portion 500 and the portion constituting the inner surface 25a in the protruding portion 500.

  The inner surface 66a of the upstream side wall portion 66 is an example of the upstream edge referred to in the present invention. The tip of the protruding portion 500, which is a connecting portion between the inner surface 66a of the upstream side wall portion 66 and the inner surface 25a of the pipe member 25 constituting the intake passage 23, is gentle, and therefore is gently formed from the inner surface 25a to the inner surface 66a. ing.

  As shown in FIG. 3, the inner surface 65 a of the bottom wall portion 65 is straight when viewed in a cross section that crosses the circumferential direction A. An angle β formed by the inner surface 65 a of the bottom wall portion 65 and the inner surface 67 a of the downstream side wall portion 67 is 90 degrees over the entire circumference in the circumferential direction A of the main channel 61. The connecting portion 91 between the inner surface 65a and the inner surface 67a is gently formed from the inner surface 65a to the inner surface 67a.

  The inner surface 66a of the upstream side wall portion 66 is linear when viewed in a cross section of the annular flow path 62 in a direction crossing the circumferential direction A. The angle γ defined by the inner surface 65a and the inner surface 66a is 90 degrees. The inner surface 66a is an example of the upstream edge referred to in the present invention. The inner surface 65a and the inner surface 66a are smoothly continuous.

  As shown in FIGS. 2 and 5, in the annular channel 62, the first regulation wall 300 and the second regulation are located at a position facing the connecting part 200 between the annular channel 62 and the exhaust gas introduction channel 80. A wall 301 is formed. Note that the position facing the connecting portion 200 is a position upstream of the annular flow path 62. In FIG. 5, the exhaust gas introduction path 80 is shown in a range. The connection part 200 is an example of the connection part said by this invention.

  The first restriction wall 300 has a concave shape toward the inflow port 63, and has a crescent shape that gradually decreases from the central portion 300a toward both ends 300b and 300c. In the first regulating wall 300, a surface 302 facing the inner surface 65a and a surface 303 facing the inflow port 63 are gently curved. A gap C1 is provided between the first restriction wall portion 300 and the inner surface 65a. The 1st control wall part 300 is an example of the control wall part said by this invention.

  The second restriction wall 301 is disposed on the upstream side of the first restriction wall 300. The 2nd control wall part 301 is concave shape toward the inflow port 63, Comprising: It is the shape of the crescent moon which becomes gradually thin toward the both ends 301b and 301c from the center part 301a. In the second restriction wall 301, a surface 304 facing the inner surface 65a and a surface 305 facing the inflow port 63 are gently curved. The 2nd regulation wall part 301 is an example of the regulation wall part said by this invention.

  A gap C <b> 2 is provided between the first and second restriction wall portions 300 and 301. The first and second restriction wall portions 300 and 301 extend from the inner surface 67 a of the downstream side wall portion 67 toward the inner surface 66 a of the upstream side wall portion 66.

  Next, the structure at a position upstream of the main flow path 61 in the intake passage 23 will be described. FIG. 6 is a side view of the vicinity of the throttle valve 24 in the intake passage 23 as seen from the side. In FIG. 6, the vicinity of the throttle valve 24 is notched in the pipe member 25, and therefore the inside of the intake passage 23 is shown. As shown in FIG. 6, the throttle portion 110 is located immediately upstream of the main flow path 61 in the intake passage 23. The restricting portion 110 is restricted so that the cross section of the flow path becomes smaller with respect to the upstream portion of the restricting portion 110. In the present embodiment, the throttle unit 110 is located downstream of the throttle valve 24.

  Next, the operation of the low pressure EGR device 50 will be described. When the exhaust gas G is supplied using the low pressure EGR device 50 in accordance with the operation state of the diesel engine 11, the low pressure EGR valve 400 is opened.

  When the low pressure EGR gas is to be supplied, that is, when the low pressure EGR valve 400 is opened, a part of the exhaust gas G flows from the exhaust passage 31 into the exhaust gas introduction passage 80. As shown in FIG. 5, the exhaust gas G that has flowed into the exhaust gas introduction path 80 flows into the annular flow path 62 from the exhaust gas introduction path 80.

  The exhaust gas G that has flowed into the annular channel 62 flows toward the downstream side along the one direction A1. At this time, as shown in the figure, the exhaust gas G flows into the main channel 61 from the inflow port 63.

  The momentum of the flow of the exhaust gas G in the annular flow path 62 is strongest at the connection portion 200 between the exhaust gas introduction path 80 and the annular flow path 62, and decreases as it flows downstream along the one direction A1.

  However, the connecting portion 200 is formed with first and second restriction wall portions 300 and 301. The amount of the exhaust gas G flowing into the inflow port 63 from the vicinity of the connecting portion 200 is restricted by the first and second restriction wall portions 300 and 301.

  Further, the exhaust gas G, which has been prevented from flowing into the inflow port 63 by the first and second restriction wall portions 300 and 301, rises downstream along the one direction A1. The exhaust gas G flowing downstream along the one direction A1 flows into the inflow port 63. As a result, the amount of exhaust gas G flowing into the main flow path 61 at each part of the inlet 63 becomes uniform. Moreover, the inflow to the inflow port 63 by the restriction wall portions 300 and 301 is not blocked, and the exhaust gas G that has passed through the vicinity of the restriction wall portions 300 and 301 toward the inflow port has both ends 300b, A vortex that turns back from 300c toward the center portion 300a or a vortex that turns back from both ends 301b and 301c of the regulating wall portion 301 toward the center portion 301a is generated. As a result, mixing of the exhaust gas G flowing from the inlet 63 into the main flow path 61 and the fresh air N is further promoted. In addition, the shape and arrangement of the first and second regulating wall portions 300 and 301 are formed so that the amount of the exhaust gas G flowing into the main flow path 61 is uniform at each part of the inflow port 63.

  In the main flow path 61, the fresh air N and the exhaust gas G that have flowed through the air cleaner 21 are uniformly mixed. For this reason, the fresh air N and the exhaust gas G in the cross section of the intake passage 23 that is perpendicular to the axial line 23a of the intake passage 23 in the downstream area of the main passage 61 in the intake passage 23 even immediately below the main passage 61. The flow velocity distribution of the air-fuel mixture M becomes substantially uniform.

  In the intake passage 23, the flow velocity distribution at a portion immediately downstream of the main flow path 61 becomes substantially uniform, so that the pressure applied to the compressor 71 is also uniform at each portion.

  FIG. 6 is a side view showing a state in which the vicinity of the throttle valve 24 is viewed from the side in the intake passage 23. In the drawing, the pipe member 25 constituting the intake passage 23 is notched in the vicinity of the throttle valve 24.

  As shown in FIG. 6, in the intake passage 23, there is a tendency that a dead water region 120 where the flow of fresh air N stagnates is formed around the throttle valve 24. The range indicated by the one-dot chain line in the figure is the dead water region 120. However, the presence of the throttle portion 110 causes a flow velocity vector toward the axial center of the intake flow path 23 to be generated in the throttle portion 110, so that the dead water region 120 moves upstream. As a result, the dead water region 120 is accommodated on the upstream side of the main channel 61. In other words, the throttle part 110 is formed so that the dead water region 120 is not formed downstream of the main channel 61 and the main channel 61. Further, since the throttle portion 110 is provided, it is possible to suppress the fresh air N flowing from the intake passage 23 to the main flow path 61 from being guided in the axial direction of the main flow path 61 and flowing into the annular flow path 62.

  Further, a connecting portion 90 between the inner surface 67a of the downstream side wall portion 67 of the annular flow path 62 and the inner surface 25a defining the intake passage 23 is gently formed (so-called R chamfering), and the upstream side wall portion 66 is formed. The exhaust gas G enters the main channel 61 from the annular channel 62 by being larger than the angle θ at the connecting portion between the inner surface 66a and the inner surface 25a formed by the inner surface 66a and the inner surface 25a defining the intake passage 23. When flowing in, the exhaust gas G is prevented from peeling off from the inner surface 25a. By separating the exhaust gas G from the inner surface 25a, the flow rate of the exhaust gas G in the vicinity of the inner surface 25a is reduced. That is, the exhaust gas G is prevented from being separated from the inner surface 25a, so that the flow velocity distribution of the air-fuel mixture M in the intake passage 23 downstream of the main flow passage 61 becomes uniform.

  Thus, in this embodiment, the amount of the exhaust gas G flowing into the main flow path 61 in each part of the inflow port 63 is made uniform by the first and second restriction wall portions 300 and 301. For this reason, in the intake passage 23, the flow velocity distribution of the air-fuel mixture M on the downstream side of the main passage 61 becomes uniform. Further, since the inflow port 63 is formed in an annular shape that continuously opens along the circumferential direction A, the resistance when the exhaust gas G flows into the intake passage 23 can be suppressed to a small value. Is efficiently guided to the intake passage 23.

  As a result, even if the compressor 71 is arranged immediately downstream of the main flow path 61 as in this embodiment, the compressor 71 and the compressor are caused by the non-uniform flow velocity distribution of the air-fuel mixture M. Occurrence of problems such as contact with the housing 71a that houses 71 and wear between the rotating shaft 73 of the compressor 71 and the bearing 74 that supports the rotating shaft 73 is prevented.

  Further, since the connecting portion 90 between the inner surface 67a and the inner surface 25a is gently formed and the angle α is 90 degrees, the exhaust gas G is further suppressed from being separated from the inner surface 25a.

  In the present embodiment, the angle α defined by the inner surface 67a and the inner surface 25a is 90 degrees, but is not limited thereto. The angle α formed by the inner surface 67a and the inner surface 25a is any value between 90 degrees and less than 180 degrees, so that the exhaust gas G is peeled off from the inner surface 25a. It is suppressed. In the range F3 in FIG. 3, for example, 120 degrees and 150 degrees are shown as other examples of angles formed by the inner surface 67a and the inner surface 65a (other than 90 degrees). Even in this case, the connecting portion 90 between the inner surface 25a and the inner surface 67a is gently formed (R chamfered).

  Next, an exhaust gas recirculation apparatus according to a second embodiment of the present invention will be described with reference to FIG. In addition, the structure which has the same function as 1st Embodiment attaches | subjects the code | symbol similar to 1st Embodiment, and abbreviate | omits description. In the present embodiment, the first and second restriction wall portions 300 and 301 are different from the first embodiment. Other structures may be the same as those in the first embodiment. The different structure will be specifically described.

  FIG. 7 is a cross-sectional view showing a state in which the connecting portion 60 is cut in the same manner as in FIG. 5 of the first embodiment. As shown in FIG. 7, the external appearances of the first and second restriction wall portions 300 and 301 may be the same as those in the first embodiment. In the present embodiment, cooling pipes 310 and 311 are provided in the first and second restriction wall portions 300 and 301. The cooling liquid L is accommodated in the cooling pipes 310 and 311. The cooling pipes 310 and 311 are connected to a pump (not shown) provided outside the annular flow path 62. The cooling liquid L is circulated by the pump. The coolant L is an example of the refrigerant referred to in the present invention.

  In the present embodiment, the first and second regulating wall portions 300 and 301 have a function of cooling the exhaust gas G with the coolant L. For this reason, the exhaust gas G in contact with the first and second restriction wall portions 300 and 301 is cooled, and hence the volume is reduced.

  As a result, in this embodiment, in addition to the effects obtained in the first embodiment, the exhaust gas G can be efficiently supplied to the main channel 61.

  Next, an exhaust gas recirculation apparatus according to a third embodiment of the present invention will be described with reference to FIG. In addition, the structure which has the same function as 1st Embodiment attaches | subjects the code | symbol same as 1st Embodiment, and abbreviate | omits description. In the present embodiment, the structures of the first and second restriction wall portions 300 and 301 are different from those in the first embodiment. Other structures may be the same as those in the first embodiment. The different structure will be specifically described.

  FIG. 8 is a cross-sectional view showing a state in which the connecting portion 60 is cut in the same manner as in FIG. 5 of the first embodiment. As shown in FIG. 8, the external appearances of the first and second restriction wall portions 300 and 301 may be the same as those in the first embodiment. In the present embodiment, the first and second restriction wall portions 300 and 301 are formed in a hollow shape. Further, the first and second restriction wall portions 300 and 301 are connected to a pump (not shown) disposed outside the annular flow path 62 by a pipe (not shown). Cooling liquid L is accommodated in the first and second regulating wall portions 300 and 301, and the cooling liquid L is circulated by the above-described pump. The coolant L is an example of the refrigerant referred to in the present invention.

  In the present embodiment, the first and second regulating wall portions 300 and 301 have a function of cooling the exhaust gas G with the coolant L. For this reason, the exhaust gas G in contact with the first and second restriction wall portions 300 and 301 is cooled, and hence the volume is reduced.

  As a result, in this embodiment, in addition to the effects obtained in the first embodiment, the exhaust gas G can be efficiently supplied to the main channel 61.

  Next, an exhaust gas circulation device according to a fourth embodiment of the present invention will be described with reference to FIGS. In addition, the structure which has the same function as 1st Embodiment attaches | subjects the code | symbol same as 1st Embodiment, and abbreviate | omits description. In the present embodiment, the structure of the bottom wall portion 65 of the annular flow path 62 is different from that of the first embodiment. Other structures may be the same as those in the first embodiment.

  FIG. 9 is a cross-sectional view showing a state in which the connecting portion 60 of this embodiment is cut in the same manner as in FIG. 3 of the first embodiment. FIG. 10 is a perspective view showing a state in which the connecting portion 60 is sectioned in the same manner as in FIG. 4 of the first embodiment and is viewed obliquely.

  As shown in FIGS. 9 and 10, the width w2 of the inner surface 65a of the bottom wall portion 65 is continuously shortened as it proceeds downstream along one direction A1. This point will be specifically described. FIG. 11 is a schematic view showing a cross section of the flow path in the annular flow path 62. The channel cross section referred to here is a channel cross section obtained by crossing the annular channel 62 in a direction crossing the circumferential direction A. In FIG. 11, first to fourth channel cross sections S1 to S4 are shown. As described above, these channel cross sections are defined by the inner surfaces (65a, 66a, 67a) of the peripheral wall portion 64. In FIG. 11, an edge 27a is shown. Note that the annular flow path 62 shown in FIG. 11 is schematically drawn to show the positions of the first to fourth flow path sections s1 to s4 in the annular flow path 62. The number and shape of the first to fourth channel cross sections s1 to s4 with respect to the channel 62 are not strict.

  First, the first and second positions P1 and P2 are set on the inner surface 65a of the annular flow path 62. The first position P1 is a position facing the connecting portion 200 on the inner surface 65a. The second position P2 is a position downstream from the first position P1 along the one direction A1. In the present embodiment, the second position P2 is a position advanced 270 degrees downstream in the circumferential direction of the main flow path 61 as an example. Specifically, a line connecting the first position P1 and the axial center line 61a is defined as a first virtual line v1. A line connecting the second position P2 and the axial center line 61a is defined as a second imaginary line v2. The angle defined by the first and second virtual lines v1 and v2 is 90 degrees.

  The first and second flow path cross sections s1 and s2 are flow path cross sections taken along a line passing through the first position P1 and the axial center line 61a. The first channel cross section s1 is located upstream of the second channel cross section s2. The third and fourth flow path cross sections s3 and s4 are flow path cross sections taken along a line passing through the second position P2 and the axial center line 61a. The third flow path section s3 is located upstream of the fourth flow path section s4.

  The width w2 of the inner surface 65a of the bottom wall portion 65 is continuously shortened from the first position P1 toward the second position P2. In the range F11 shown in FIG. 11, the widths w1 to w3 and the areas of the first to fourth channel cross sections s1 to s4 are shown.

  As shown in the range F11, the width w1 of the inlet 63 of the first to fourth channel cross sections s1 to s4 and the width w2 of the inner surface 65a of the bottom wall portion 65 are the inlet 63 of the first channel cross section s1. The relative value with respect to the reference length when the width w1 is set to the reference length 1 is shown.

  In the first flow path section s1 at the first position P1, the width w1 of the inflow port 63 is 1. The width w2 of the inner surface 65a is 1. In the third flow path section s3, the width w1 of the inflow port 63 is 1. The width w2 of the inner surface 65a is 0.8. In the second flow path section s2, the width w1 of the inflow port 63 is 1. The width w2 of the inner surface 65a is 0.6. In the fourth flow path section s4 at the second position P2, the width w1 of the inflow port 63 is 1. The width w2 of the inner surface 65a is 0.4.

  In the range F11, the width w3, which is the length between the inlet 63 of the first to fourth channel cross sections s1 to s4 and the inner surface 65a, is the width w1 of the inlet 63 of the first channel cross section s1. The relative value with respect to the reference length is shown by setting the length of the width w3 in the first flow path section s1 as the reference length 1, and not the relative value with respect to the reference length.

  The width w3 of the first flow path section s1 at the first position P1 is 1. The width w3 of the third flow path section s3 is 0.7. The width w3 of the second flow path section s2 is 0.6. The width w3 of the fourth flow path section s4 at the second position P2 is 0.5.

  In the range F11, the areas of the first to fourth channel cross sections s1 to s4 are relative to the reference value with the area of the first channel cross section s1 as the reference value 1. The area of the first flow path section s1 is 1. The area of the third flow path section s3 is 0.63. The area of the second flow path section s2 is 0.48. The area of the fourth channel cross section s4 is 0.35.

  The angle α defined by the inner surface 67a of the downstream side wall portion 67 and the inner surface 65a of the bottom wall portion 65 is 90 degrees as in the first embodiment. The inner surfaces 65a and 66a are smoothly continuous. However, as in the first embodiment, if the angle α is fixed to any value of 90 degrees or more and less than 180 degrees, the same actions and effects as in the first embodiment can be obtained.

  The width w2 of the inner surface 65a is shortened by changing the angle β defined by the inner surface 65a and the inner surface 66a of the upstream side wall 66 by shortening the end 65b of the inner surface 65a toward the downstream side wall 67. .

  In the present embodiment, the width w2 of the inner surface 65a of the bottom wall portion 65 is continuously reduced along the one direction A1, so that in addition to the effects of the first embodiment, on the downstream side of the annular flow path 62. Also, the exhaust gas G easily flows into the main flow path 61. This point will be specifically described.

  When the exhaust gas G flows into the annular flow channel 62 from the exhaust gas introduction channel 80, a part of the exhaust gas G flows along the inner surface 65 a of the bottom wall portion 65 due to the flow force. For this reason, the exhaust gas G flowing toward the downstream along the bottom wall portion 65 tends not to flow into the main flow path 61.

  However, as the annular flow path 62 goes downstream, the width w2 of the inner surface 65a of the bottom wall portion 65 decreases, so that the exhaust gas G flowing along the bottom wall portion 65 flows inward (to the inflow port 63 side). Pushed out. This makes it easier for the exhaust gas G to flow into the main flow path 61 on the downstream side of the annular flow path 62. The relative relationship between the widths w1 and w2 is set so that the amount of exhaust gas G flowing from each part of the inflow port 63 is uniform.

  Further, when the width w2 of the bottom wall portion 65 is reduced, the angle α defined by the inner surface 67a of the downstream side wall portion 67 and the inner surface 25a of the pipe member 25 that defines the intake passage 23 is kept constant. . In the present embodiment, as an example, it is 90 degrees as in the first embodiment, but any angle that is 90 degrees or more and less than 180 degrees may be used. For this reason, it is suppressed that the exhaust gas G peels from the inner surface 25a of the pipe member 25.

  The present embodiment has a structure in which the width w2 of the inner surface 65a is continuously shortened toward the downstream in the connecting portion 60 described in the first embodiment. Similarly, the second and third embodiments may have a structure in which the width w2 of the inner surface 65a is shortened. In this case, in addition to the effects of the second and third embodiments, the same operations and effects as the present embodiment can be obtained.

  In the first to fourth embodiments, two restriction wall portions (first and second restriction wall portions 300 and 301) are used as an example of the restriction wall portion referred to in the present invention. However, the number of restriction walls is not limited to two. For example, three or four other plural numbers may be used, or only one may be used.

  In the first to fourth embodiments, the exhaust gas recirculation device of the present invention is used as the low pressure EGR device 50 as an example. However, it is not limited to being used only as the low pressure EGR device 50.

  In the first to fourth embodiments, the inflow port 63 has been described as an annular long hole that continuously opens along the circumferential direction A. However, a plurality of the inflow ports 63 may exist. As the diameter of the inlet hole on the position P1 side of 1 is reduced and the second position P2 is advanced, the diameter of the inlet hole is increased or the diameter of the inlet hole is made equal. The number of inflow ports on the position P1 side may be reduced, and the number of inflow ports may be increased as the position proceeds to the second position P2 side.

The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, you may delete some components from all the components shown by embodiment mentioned above. Furthermore, you may combine the component covering different embodiment suitably.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1]
An intake passage through which intake air flows;
An annular flow path that extends along the circumferential direction of the intake passage, is formed in an annular shape, and surrounds the intake passage on the inside;
An inlet that extends in the circumferential direction of the intake passage between the intake passage and the annular flow path and is formed in an annular shape, and communicates the intake passage and the annular flow path;
An exhaust gas introduction path that communicates with the annular flow path and guides the exhaust gas into the annular flow path so as to flow in one of the circumferential directions;
A restricting wall portion provided at a connection portion between the exhaust gas introduction path and the annular flow path and restricting the inflow of the exhaust gas to the inflow port;
An exhaust gas recirculation device comprising:
[2]
The restriction wall portion has a crescent shape that is concave toward the inflow port.
The exhaust gas recirculation apparatus according to [1], wherein
[3]
Refrigerant flows through the regulation wall
The exhaust gas recirculation apparatus according to [1] or [2], wherein
[4]
From the angle formed by the inner wall surface of the annular flow path that forms the upstream opening edge of the intake passage at the inlet and the inner wall surface of the intake passage, the downstream opening edge of the intake passage at the inlet is The angle formed by the inner wall surface of the annular channel to be formed and the inner wall surface of the intake passage is increased.
The exhaust gas recirculation apparatus according to any one of [1] to [3].
[5]
A throttle portion for reducing the cross-sectional area of the intake passage is formed on the upstream opening edge side of the intake passage at the inlet.
The exhaust gas recirculation apparatus according to any one of [1] to [4].
[6]
Of the edges defining the channel cross section, the width of the bottom edge facing the inlet is continuously reduced as it proceeds downstream along the one direction.
The exhaust gas recirculation apparatus according to any one of [1] to [5].

  DESCRIPTION OF SYMBOLS 23 ... Intake passage, 50 ... Low pressure EGR apparatus (exhaust gas recirculation apparatus), 61 ... Main flow path, 62 ... Annular flow path, 63 ... Inlet, 80 ... Exhaust gas introduction path, 200 ... Connection part, 300 ... 1st regulation Wall part (regulatory wall part), 301 ... second restricting wall part (regulatory wall part), A ... circumferential direction, A1 ... one direction, L ... cooling device, α ... angle (downstream side opening of intake passage of inlet) Angle formed by the inner wall surface of the annular flow path forming the edge and the inner wall surface of the intake passage), θ ... angle (the inner wall surface of the annular flow path forming the upstream opening edge of the intake passage of the inlet and the intake passage) The angle between the inner wall and the inner wall.

Claims (6)

An intake passage through which intake air flows;
A main flow path that is part of the intake passage;
An annular flow path that extends along the circumferential direction of the intake passage, is formed in an annular shape, surrounds the intake passage on the inner side, is formed around the main flow path, and communicates with the main flow path;
An inlet that extends in the circumferential direction of the intake passage between the intake passage and the annular flow path and is formed in an annular shape, and communicates the intake passage and the annular flow path;
An exhaust gas introduction path that communicates with the annular flow path and guides exhaust gas into the annular flow path so as to flow in one of the circumferential directions;
The exhaust gas introduction path is connected to the annular flow path at a position that does not overlap the main flow path in the flow direction of the exhaust gas when flowing into the annular flow path from the exhaust gas introduction path,
In the annular channel, at a position facing the connecting portion between the annular channel and the exhaust gas introduction path, a regulation wall portion is provided with a gap between them,
An exhaust gas recirculation apparatus , wherein a cooling pipe is provided in the regulation wall portion, and a refrigerant flows in the cooling pipe . The exhaust gas recirculation apparatus according to claim 1, wherein the restriction wall portion has a crescent shape that is concave toward the inflow port. From the angle formed by the inner wall surface of the annular flow path that forms the upstream opening edge of the intake passage at the inlet and the inner wall surface of the intake passage, the downstream opening edge of the intake passage at the inlet is The exhaust gas recirculation apparatus according to claim 1 or 2 , wherein an angle formed by an inner wall surface of the annular flow path to be formed and an inner wall surface of the intake passage is increased. The throttle part which makes the flow-path cross-sectional area of the said intake passage small is formed in the upstream opening edge part side of the said intake passage of the said inflow port. Any one of Claims 1-3 characterized by the above-mentioned. The exhaust gas recirculation device described. Of the edges defining the flow path cross-section, the width of the inlet opposed to the bottom edge is, of claims 1-4, characterized in successively smaller it as it travels downstream along the one direction The exhaust gas recirculation device according to any one of the above. According to any one of claims 1-5, characterized in that the circumferential direction of the exhaust gas flows out of the same direction as the rotation of the compressor provided in the intake passage Exhaust gas recirculation device.

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