JP2012237236A - Exhaust gas recirculation system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation system of an internal combustion engine which can suppress the formation of a water film in a filter for preventing a foreign matter from entering a recirculating exhaust gas, and can prevent an exhaust cleaning device or the like from being damaged.SOLUTION: The exhaust gas recirculation system includes: an exhaust pipe 42 having a cylindrical case 51 housing a PM collection filter 52 in an exhaust passage 42W; an exhaust recirculation pipe 71 recirculating exhaust from a specific passage 53 into an intake passage 32w; and a foreign matter collecting filter 80 attached near upstream end 71u of the exhaust recirculation pipe to collect the foreign matter in the recirculating exhaust gas. The specific passage 53 is formed in a space that is more downstream than the PM collection filter 52 in the cylindrical case 51. The foreign matter collecting filter 80 has a protruded part 82 protruding to the specific passage 53 in the cylindrical case 51 where a protruding direction is oriented to tilt toward a downstream exhaust direction.

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine, and more particularly to an exhaust gas recirculation device for an internal combustion engine provided with a foreign matter collecting filter in an exhaust gas recirculation path.

  In a vehicle engine (internal combustion engine), an exhaust gas recirculation device is provided to perform exhaust gas recirculation (hereinafter also referred to as EGR (Exhaust Gas Recirculation)) effective in reducing NOx (nitrogen oxide). However, the HPL (High Pressure Loop) -EGR system, which recirculates some of the hot exhaust gas to the intake side, has passed through the turbocharger exhaust turbine and exhaust aftertreatment device. An exhaust gas recirculation device of LPL (Low Pressure Loop) -EGR system that enables exhaust gas recirculation at a low temperature by recirculating exhaust gas upstream of the compressor of the turbocharger has become widespread.

  In such an EGR system, foreign matter such as spatter (spatters at the time of welding) and falling pieces from the exhaust gas purification device may be generated in the exhaust pipe for returning the exhaust gas to the intake passage side. A foreign matter collecting filter (so-called FOD filter) is provided in the exhaust gas recirculation path so that it does not enter the compressor of the turbocharger and cause damage.

  As an LPL-EGR system equipped with this foreign matter collection filter, for example, an EGR filter that collects exhaust system foreign matter in EGR gas flowing through the low pressure EGR passage, and the EGR filter held in a state of rattling against the low pressure EGR pipe There is known a device that includes a holding unit that captures the exhaust system foreign matter shaken off from the EGR filter (see, for example, Patent Document 1).

  In addition, an EGR gas pickup pipe provided with a foreign matter collecting filter is inserted downstream of the exhaust turbine of the turbocharger and upstream of the filter portion in the DPF (diesel particulate filter) device. There is also known an apparatus in which EGR gas is recirculated to the upstream side from the compressor of the turbocharger by using the back pressure obtained by the filter portion of the DPF unit in the axial direction (see, for example, Patent Document 2). ).

JP 2010-138745 A JP 2003-535264 A

  However, in the conventional exhaust gas recirculation device for an internal combustion engine as described above, the foreign matter collecting filter in the low pressure EGR pipe is easy to form a water film with a fine mesh, so that the exhaust gas recirculation passage is a water film. The foreign matter collecting filter that forms the gas is likely to be clogged, and a required amount of exhaust gas is not recirculated, so that the NOx reduction effect may be reduced.

  Even when acidic condensate generated by an EGR cooler is difficult to enter the intake system, the condensate flows back into the exhaust pipe and rapidly cools the ceramic catalyst substrate in the exhaust purification system. As a result, there is a concern that the exhaust purification device may be damaged.

  Therefore, the present invention effectively suppresses the formation of a water film on a foreign matter collecting filter that prevents foreign matter from entering into the recirculated exhaust gas, and can reliably prevent damage to an exhaust purification device or the like. An exhaust gas recirculation device is provided.

  In order to solve the above problems, an exhaust gas recirculation device for an internal combustion engine according to the present invention is (1) a cylinder that forms an exhaust gas passage through which the exhaust gas of the internal combustion engine passes and accommodates an exhaust purification unit in the middle of the exhaust gas passage. An exhaust pipe having a cylindrical case portion, an exhaust recirculation pipe for recirculating the exhaust gas from a specific passage portion of the exhaust gas passage to the intake passage side of the internal combustion engine, and an upstream end portion of the exhaust recirculation pipe A foreign matter collecting filter that collects foreign matter in exhaust gas recirculated from the specific passage portion to the intake passage side, wherein the specific passage portion includes the specific passage portion, A projecting surface shape portion formed by an internal space downstream of the exhaust purification unit in the inside of the cylindrical case portion, wherein the foreign matter collecting filter protrudes from the inner wall surface of the cylindrical case portion to the inner space side. And having, projecting direction of the projecting surface shaped portion, characterized in that it is oriented to be inclined to the downstream side of the exhaust gas passage.

  In this invention, since the foreign matter collecting filter has a projecting surface shape portion projecting inside the cylindrical case portion, the foreign matter collecting filter is projected even when the recirculated exhaust gas does not flow into the exhaust recirculation passage. It is always exposed to the exhaust gas passing through the exhaust gas passage in a relatively large area on the shape portion side, and intersects the direction of the exhaust gas flow in the exhaust gas passage. Therefore, the evaporation of water adhering to the foreign matter collecting filter is promoted, the formation of a water film on the foreign matter collecting filter is effectively suppressed, and the passage in the exhaust gas recirculation pipe is blocked by the foreign matter collecting filter. Will be prevented. In addition, since the protruding direction of the protruding surface shape portion of the foreign matter collecting filter is oriented so as to incline downstream in the exhaust direction, the condensed water flows backward from the inside of the exhaust recirculation pipe to the inside of the cylindrical case portion. Even so, the flow of the condensed water is directed toward the downstream side in the exhaust direction, and the concern that the exhaust purification unit is rapidly cooled by the condensed water is eliminated, and the foreign matter collecting filter has an increased area. By sufficiently heating on the surface side, formation of a water film on the foreign matter collecting filter can be effectively suppressed.

  In the exhaust gas recirculation device for an internal combustion engine according to the present invention, (2) an upstream filter surface in which the protruding surface shape portion of the foreign matter collecting filter is disposed facing an upstream portion of the exhaust gas passage; A downstream filter surface disposed facing the downstream portion of the exhaust gas passage and disposed so as to be biased downward in the vertical direction from the upstream filter surface, and the upstream filter It is desirable that the fluid resistance of the foreign matter collecting filter on the surface is larger than the fluid resistance of the foreign matter collecting filter on the downstream filter surface.

  In this case, the condensed water flowing backward in the exhaust gas recirculation pipe toward the exhaust gas passage easily passes through the downstream filter surface, and the exhaust gas that has passed through the exhaust purification unit passes through the upstream filter surface of the foreign matter collecting filter. It becomes easy to heat. Therefore, the flow of the condensed water is likely to go downstream in the exhaust direction, and the upstream filter surface side of the foreign matter collecting filter is sufficiently heated, and the evaporation of water adhering to the foreign matter collecting filter is promoted.

  In the case of having the configuration described in (2) above, preferably, (3) the mesh of the foreign matter collecting filter on the upstream filter surface is finer than the mesh of the foreign matter collecting filter on the downstream filter surface. Yes. This makes it possible to employ a simple foreign matter collecting filter, although it has a direction of mounting to the exhaust gas recirculation pipe or the cylindrical case part.

  In the exhaust gas recirculation device for an internal combustion engine according to the present invention, (4) the opening position where the exhaust gas passage portion downstream of the specific passage portion opens into the cylindrical case portion is the position of the cylindrical case portion. It is preferable that the foreign matter collecting filter is located on the lower side in the vertical direction from the protruding position of the protruding portion of the foreign matter collecting filter from the inner wall surface.

  With this configuration, the condensed water flowing backward from the exhaust gas recirculation pipe easily flows down to the downstream side in the exhaust direction, and the acidic condensed water does not easily accumulate in the cylindrical case portion.

  In the exhaust gas recirculation device for an internal combustion engine having the configuration described in (4) above, (5) the foreign matter collecting filter includes an exhaust gas passage downstream in the projecting direction of the projecting surface shape portion from the specific passage portion. It is preferable to be arranged so as to be directed to the opening position of the part. Thereby, the condensed water flowing backward from the exhaust gas recirculation pipe into the cylindrical case portion is easily discharged downstream in the exhaust direction.

  In the case of having the configuration described in (5) above, (6) the cylindrical case portion has a cone-shaped portion that forms the specific passage portion on the outlet side of the exhaust purification unit, and the outlet of the exhaust purification unit The flow of the exhaust gas entering the specific passage part from the projecting position side toward the projecting position side is folded back from the projecting position side toward the opening position side along the cone-shaped part of the cylindrical case part. Is preferred. In this case, it is possible to easily secure the discharge path of the condensed water that has entered the cylindrical case portion, and to make the exhaust pipe structure easy to assemble and maintain.

  According to the present invention, the foreign matter collecting filter is provided with the projecting surface shape portion projecting inside the cylindrical case portion, and the projecting direction is inclined to the downstream side in the exhaust direction. Even when the recirculated exhaust gas does not flow in, the foreign matter collecting filter can always be exposed to the exhaust gas passing through the exhaust gas passage with a relatively large area on the projecting surface side, and the upstream area where the area becomes larger Even if the condensed water flows back from the inside of the exhaust gas recirculation pipe to the inside of the cylindrical case part, the flow of the condensed water is directed downstream in the exhaust direction. Can be attached. As a result, it is possible to effectively suppress the formation of a water film on the foreign matter collecting filter that prevents foreign matters from entering the recirculated exhaust gas, and to prevent damage to the exhaust purification device or the like, and to prevent the exhaust gas from being regenerated. A circulation device can be provided.

1 is a schematic configuration diagram of an entire exhaust gas recirculation device for an internal combustion engine according to an embodiment of the present invention, in which a pipe is shown in a transparent state. It is a principal part block diagram of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on one Embodiment of this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a figure which shows the some deformation | transformation aspect of the foreign material collection filter in the exhaust gas recirculation apparatus of the internal combustion engine which concerns on one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(One embodiment)
1 to 4 show an embodiment of an exhaust gas recirculation device for an internal combustion engine according to the present invention.

  In this embodiment, the present invention is applied to an in-line four-cylinder diesel engine 10 (hereinafter simply referred to as the engine 10) which is a multi-cylinder internal combustion engine.

  As shown in FIG. 1, the engine 10 of the present embodiment has a plurality of cylinders 11 in a main body block 10M. The engine 10 includes combustion chambers (details are not shown) in each cylinder 11. A common rail fuel injection device 12 for injecting fuel into the combustion chamber, an intake device 13 for inhaling air into the combustion chamber, an exhaust device 14 for exhausting exhaust gas from the combustion chamber, and exhaust energy in the exhaust device 14 Then, the turbocharger 15 that compresses the intake air in the intake device 13 and supercharges the air into the combustion chamber, and returns a part of the high-pressure side exhaust gas upstream from the turbocharger 15 to the intake side. HPL (High Pressure Loop) -EGR device 16 which is an exhaust gas recirculation device on the high pressure side to be recirculated and a part of the low pressure exhaust gas downstream from the turbocharger 15 is recirculated to the intake side and recirculated. Circulating low pressure side exhaust And LPL (Low Pressure Loop) -EGR device 17 is a circular device is equipped.

  The fuel injection device 12 includes a supply pump 21 that draws fuel from a fuel tank (not shown), pressurizes the fuel to a high fuel pressure (fuel pressure), and discharges the fuel, a common rail 22 into which fuel from the supply pump 21 is introduced, and the common rail And a fuel injection valve 23 that injects the fuel supplied through the cylinder 22 into the combustion chamber at a timing and opening degree (duty ratio) corresponding to an injection command signal from an ECU (electronic control unit) (not shown). The supply pump 21 is driven using, for example, the rotational power of the engine 10, and the common rail 22 distributes and supplies the high-pressure fuel supplied from the supply pump 21 to the plurality of fuel injection valves 23 while keeping it even. The fuel injection valve 23 is composed of a known needle valve that is electromagnetically driven, and the valve opening time is controlled in accordance with the injection command signal, whereby a fuel (for example, light oil) of a fuel injection amount corresponding to the injection command signal is supplied. It can be injected and supplied into the combustion chamber.

  The intake device 13 includes an intake manifold 31, an intake pipe 32 upstream from the intake manifold 31, an air cleaner 33 that cleans intake air by a filter at the most upstream portion of the intake pipe 32, and a turbocharger 15. An intercooler 34 that cools through intake air that has been heated by compression / supercharging by the intake air compressor 15a in the downstream intake passage portion 32wb, an air flow meter 35 that detects the intake flow rate of fresh air, and the engine 10 A throttle valve 36 for adjusting the intake air amount, an intake air temperature sensor 37 for detecting the intake air temperature, and an intake pipe pressure sensor 38 for detecting the boost pressure of the engine 10 near the inlet of the intake manifold 31 are provided. Yes.

  The exhaust device 14 is configured to restrict the exhaust temperature during idle or light load by restricting the exhaust manifold 41, the exhaust pipe 42 downstream of the exhaust manifold 41, and the exhaust gas passage 42w in the exhaust pipe 42 at a predetermined position downstream thereof. The exhaust throttle valve 43 that can control the back pressure of the LPL-EGR device 17 and the known oxidation catalytic converter 44 and DPF mounted on the exhaust pipe 42 downstream of the turbocharger 15. And an exhaust aftertreatment device 46 (exhaust gas purification device) comprising a (diesel particulate filter) unit 45.

  Although the detailed configuration is not shown, the turbocharger 15 includes an intake air compressor 15a and an exhaust turbine 15b that are integrally coupled to each other in the rotational direction, and rotates the exhaust turbine 15b with exhaust energy and also uses the intake air compressor 15a. By rotating, the intake air compressor 15 a can compress the intake air and supply positive pressure air into the engine 10.

  The HPL-EGR device 16 is mounted between the HPL-EGR pipe 61 and the HPL-EGR pipe 61 interposed between the exhaust manifold 41 and the intake pipe 32, and adjusts the recirculation amount of the exhaust gas. An HPL-EGR valve 62 that can be used, and an HPL-EGR cooler 63 that can cool the exhaust gas passing through the HPL-EGR pipe 61 on the way. The HPL-EGR pipe 61 bypasses the combustion chamber in the engine 10, and the exhaust gas passage portion 42 wa upstream of the exhaust turbine 15 b in the exhaust gas passage 42 w in the exhaust pipe 42 or the exhaust gas passage in the exhaust manifold 41. A high-pressure side exhaust recirculation passage P1 is formed to communicate the portion with the intake passage portion 32wb on the downstream side of the intake air compressor 15a in the intake passage 32w in the intake pipe 32. Further, the HPL-EGR valve 62 is in an open state in which the high pressure side exhaust gas recirculation passage P1 is opened, and in a closed state in which the opening of the high pressure side exhaust gas recirculation passage P1 is restricted, for example, the high pressure side exhaust gas recirculation passage P1 is shut off. It is possible to switch to. Although not shown in detail, the HPL-EGR cooler 63 is provided with a cooling water pipe portion that contacts the EGR gas in a case portion that forms a part of the high-pressure side exhaust gas recirculation passage P1, and is used for cooling that is introduced into the cooling water pipe portion. The high-pressure side recirculated exhaust gas can be cooled by heat exchange between the fluid (for example, engine cooling water) and the high-pressure recirculated exhaust gas passing through the case portion.

  The LPL-EGR device 17 is installed in the middle of the LPL-EGR pipe 71 interposed between the exhaust pipe 42 and the intake pipe 32 and adjusts the recirculation amount of the exhaust gas. LPL-EGR valve 72, LPL-EGR cooler 73 as an exhaust cooler capable of cooling exhaust gas passing through LPL-EGR pipe 71, and exhaust gas passage in exhaust pipe 42 on the downstream side 42w has the exhaust throttle valve 43 that can reduce the opening degree so that the exhaust gas passage portion downstream of the DPF unit 45 in the portion 42w is throttled.

  The LPL-EGR pipe 71 bypasses the combustion chamber in the engine 10 and out of the exhaust gas passage 42 w in the exhaust pipe 42, the low pressure exhaust gas passage portion 42 wb on the downstream side of the exhaust turbine 15 b and the intake passage in the intake pipe 32. A low-pressure side exhaust recirculation passage P2 (low-pressure side exhaust recirculation path) that communicates with the intake passage portion 32wa upstream of the intake air compressor 15a is formed in 32w, and is purified by the oxidation catalyst converter 44 and the DPF unit 45. A low-pressure side exhaust recirculation pipe is configured to recirculate exhaust gas from the exhaust gas passage 42w side to the intake passage 32w side. The LPL-EGR valve 72 is in an open state in which the low pressure side exhaust gas recirculation passage P2 is opened, and in a closed state in which the opening of the low pressure side exhaust gas recirculation passage P2 is restricted, for example, the low pressure side exhaust gas recirculation passage P2 is shut off. It is possible to switch to. Furthermore, the LPL-EGR cooler 73 includes a case portion 73a that forms part of the low-pressure side exhaust recirculation passage P2, and a cooling water pipe portion 73b that contacts the EGR gas passing through the case portion 73a and forms a cooling fluid passage. And the low-pressure side recirculated exhaust gas by heat exchange between the cooling fluid (for example, engine cooling water) introduced into the cooling water pipe portion 73b and the recirculated exhaust gas passing through the case portion 73a. Can be cooled. The low-pressure side exhaust recirculation passage P2 is a low-pressure in the LPL-EGR device 17 together with a portion of the intake passage 32w in the intake pipe 32 downstream of the connection position j where the LPL-EGR pipe 71 is connected to the intake pipe 32. Side exhaust gas recirculation path.

On the other hand, the oxidation catalyst converter 44 and the DPF unit 45 are disposed in the middle of the exhaust pipe 42 of the engine 10 and serve as an exhaust purification unit that purifies exhaust gas passing through the inside. That is, the oxidation catalyst converter 44 has an oxidation catalyst function that can change, for example, hydrocarbon (HC) and carbon monoxide (CO) into carbon dioxide (CO ₂ ) and water (H ₂ O). The DPF unit 45 has, for example, a honeycomb structure having a porous ceramic substrate, and collects particulate matter (PM) contained in the exhaust gas of the engine 10 and burns PM deposited by the collection. The playback process can be performed.

  As shown in FIGS. 2 to 4, specifically, the DPF unit 45 is housed in a cylindrical case portion 51 that is disposed in the middle of the exhaust pipe 42 and extends the exhaust gas passage 42 w in a specific passage section. The PM collection filter portion housed in the cylindrical case portion 51 so as to collect PM in the exhaust gas passing through a specific passage section in the cylindrical case portion 51 and purify the exhaust gas. 52 (exhaust gas purification unit).

  The cylindrical case portion 51 gradually reduces the cross-sectional area of the passage downstream of the PM collection filter portion 52 on the downstream side of the PM collection filter portion 52 in the expanded passage section of the exhaust gas passage 42w on the downstream side of the PM collection filter portion 52. The inner wall surface 51a (inclined inner wall surface) that inclines and intersects with the cylindrical wall portion 51b around the PM collection filter portion 52 in the reduced diameter direction (direction in which the diameter decreases).

  Further, an exhaust as a specific passage portion located in the downstream portion of the passage section extended corresponding to the PM collection filter portion 52 is disposed inside the cylindrical case portion 51 on the downstream side of the PM collection filter portion 52. A gas distribution chamber 53 is defined, and an exhaust gas passage portion 42wc downstream of the exhaust gas distribution chamber 53 in the exhaust gas passage 42w (hereinafter simply referred to as an exhaust gas passage portion 42wc on the downstream side) is the exhaust gas distribution. For example, the low-pressure side exhaust recirculation passage P2 is curved while extending from the exhaust gas distribution chamber 53 to the upper side in FIG. 2, which is the upper side in the vertical direction, for example, from the chamber 53 to the rear side of the vehicle (lower side in FIG. 1). ing.

  On the other hand, in the vicinity of the upstream end 71u of the LPL-EGR pipe 71 forming the low pressure side exhaust recirculation passage P2, a cylindrical case portion constituting a part of the inner wall surface of the upstream end 71u or the exhaust pipe 42 in the vicinity thereof. A foreign matter collecting filter 80 protruding from the inner wall surface 51a of the 51 into the exhaust gas passage 42w is provided.

  The foreign matter collecting filter 80 is a metal mesh having a mesh sufficiently finer than the plurality of parallel passage holes 52h of the honeycomb-shaped PM collecting filter portion 52 of the DPF unit 45 (a mesh made of metal wire, a porous mesh). From the upstream side of the PM collection filter unit 52, spatter (spattering material during welding) present in the exhaust pipe 42, dropping pieces from the PM collection filter unit 52, or from the upstream side of the PM collection filter unit 52 When foreign matter moving with the exhaust gas is generated, the foreign matter is captured, and such foreign matter is prevented from entering the intake air compressor 15a of the turbocharger 15 and causing damage. Yes.

  Further, the foreign matter collecting filter 80 is disposed in the vicinity of the upstream end 71u of the LPL-EGR pipe 71 and from the inner wall surface 51a of the cylindrical case portion 51 on the downstream side of the PM collecting filter portion 52 of the DPF unit 45 to the exhaust gas passage. It protrudes into the exhaust gas distribution chamber 53 which is a part of 42w.

  Specifically, the foreign matter collecting filter 80 includes an annular base end portion 81 supported by at least one of these in the vicinity of a connection portion between the cylindrical case portion 51 and the LPL-EGR pipe 71, and an annular base end on the outer peripheral side. The protrusion 81 is supported by the portion 81 and protrudes into the exhaust gas distribution chamber 53 in a substantially conical shape.

  In addition, the annular base end portion 81 is previously welded to the upstream end portion 71u of the LPL-EGR pipe 71, for example, and the upstream end portion 71u of the LPL-EGR pipe 71 is connected to the cylindrical case portion 51 in that state. Further, it is supported by the cylindrical case portion 51.

  By the way, in the engine 10 of the present embodiment, the low pressure side exhaust gas recirculation passage P2 formed by the LPL-EGR device 17 with respect to the recirculation exhaust gas in the high pressure side exhaust gas recirculation passage P1 formed by the HPL-EGR device 16. The recirculated exhaust gas in the low-pressure side and the low-temperature side of the recirculated exhaust gas is cooled by the LPL-EGR cooler 73 in the low-pressure side exhaust recirculation passage P2, so that the LPL-EGR Acidic condensed water is easily generated in the cooler 73. In addition, since the foreign matter collecting filter 80 is made of metal and has a fine mesh, a water film is easily attached to the surface of the foreign matter collecting filter 80 due to surface tension.

  Therefore, in the present embodiment, the exhaust gas distribution chamber 53 is formed by the internal space on the downstream side of the PM collection filter portion 52 in the inside of the cylindrical case portion 51, and the foreign matter collection filter 80 has a cylindrical shape. It has a projecting surface shape portion 82 projecting from the inner wall surface 51a of the case portion 51 to the inner space side, and the projecting direction of the projecting surface shape portion 82 is inclined toward the downstream side of the exhaust gas passage 42w. It is attached.

  Specifically, as shown in FIGS. 3 and 4, the cylindrical case portion 51 constituting a part of the exhaust pipe 42 forms an exhaust gas distribution chamber 53 on the outlet 52 e side of the PM collection filter portion 52. It has a cone-shaped portion 51 c, and an opening position C 1 at which the exhaust gas passage portion 42 wc downstream from the exhaust gas distribution chamber 53 opens into the exhaust gas distribution chamber 53 is from the inner wall surface 51 a of the cylindrical case portion 51. It is located on the lower side in the vertical direction (vertical direction in FIG. 3) with respect to the protruding position C2 of the projecting shape portion 82 of the foreign matter collecting filter 80.

  Further, in the foreign matter collecting filter 80, the protruding direction of the protruding portion 82 is at an opening position C1 that is an opening position into the exhaust gas distribution chamber 53 of the exhaust gas passage portion 42wc on the downstream side of the exhaust gas distribution chamber 53. The projecting direction of the projecting surface shape portion 82 is oriented so as to incline toward the opening position C1 so as to face.

  On the other hand, the flow of the exhaust gas entering the exhaust gas distribution chamber 53 from the outlet 52e of the PM collection filter unit 52 flows along the cone-shaped portion 51c of the cylindrical case portion 51 from the protruding position C2 side of the protruding surface shape portion 82. The downstream exhaust gas passage portion 42wc flows into the PM collection filter portion 52 (passage axis parallel to the passage hole 52h) so that the downstream exhaust gas passage portion 42wc flows back toward the opening position C1 side. On the other hand, the spacer 88 is spaced apart in parallel to the side.

  More specifically, the projecting surface shape portion 82 of the foreign matter collecting filter 80 has an upstream filter surface 83 disposed facing the upstream portion of the exhaust gas passage 42w and a downstream portion of the exhaust gas passage. And a downstream filter surface 84 disposed so as to be biased downward in the vertical direction from the upstream filter surface 83.

  Further, the foreign matter trapping is performed such that the fluid resistance (filtration resistance) during filtration of the foreign matter collection filter 80 on the upstream filter surface 83 is larger than the fluid resistance during filtration of the foreign matter collection filter 80 on the downstream filter surface 84. The mesh (mesh size) on the upstream filter surface 83 of the collection filter 80 is finer than the mesh on the downstream filter surface 84 of the foreign matter collection filter 80.

  In addition, the LPL-EGR pipe 71 passes the condensed water generated in the LPL-EGR cooler 73 from the upstream end 71u side through the foreign matter collection filter 80 in the exhaust gas passage 42w downstream from the PM collection filter unit 52, That is, the exhaust gas distribution chamber 53 descends from an unillustrated inlet portion of the LPL-EGR cooler 73 toward the inner wall surface 51 a side of the cylindrical case portion 51 on the downstream side of the PM collection filter portion 52 so as to be discharged into the exhaust gas distribution chamber 53. Thus, it extends at least vertically in the vertical direction.

  The engine 10 is controlled by an ECU (electronic control unit) (not shown) based on sensor information of various sensor groups. For example, discharge control of the supply pump 21 (for example, control of the electromagnetic spill valve). ), Fuel injection amount control by the fuel injection valve 23, opening degree control of the throttle valve 36, opening degree (EGR rate) control of the HPL-EGR valve 62 and LPL-EGR valve 72, and opening degree control of the exhaust throttle valve 43 Control and the like are executed. The various sensor groups referred to here include, for example, the known air flow meter 35, intake temperature sensor 37, intake pipe pressure sensor 38, exhaust oxygen concentration sensor 47, exhaust temperature sensors 48a and 48b, exhaust temperature sensor 49, DPF shown in FIG. In addition to the front-rear differential pressure sensor 91, the low pressure EGR differential pressure sensor 92, and the like, there are an accelerator opening sensor, a throttle opening sensor, a crank angle sensor, a water temperature sensor, a vehicle speed sensor, and the like (not shown). Further, instead of the exhaust throttle valve 43 or in combination with the exhaust throttle valve 43, a low pressure EGR intake throttle valve 93 may be provided in the upstream intake passage portion 32wa.

  Next, the operation will be described.

  In the exhaust gas recirculation device for an internal combustion engine of the present embodiment configured as described above, the foreign matter collecting filter 80 has the protruding surface shape portion 82 that protrudes into the cylindrical case portion 51. Even when the recirculated exhaust gas does not flow into the low-pressure side exhaust recirculation passage P2, the foreign matter collecting filter 80 converts the exhaust gas passing through the exhaust gas passage 42w in a relatively large area on the projecting surface portion 82 side. In addition, the upstream filter surface 83 and the downstream filter surface 84 intersect each other with respect to the flow direction of the exhaust gas in the exhaust gas passage 42w. Therefore, evaporation of water adhering to the foreign matter collecting filter 80 is promoted, and formation of a water film on the foreign matter collecting filter 80 is effectively suppressed, and the exhaust gas recirculation passage P2 in the LPL-EGR pipe 71 becomes foreign matter. Blocking by the collection filter 80 is prevented.

  Further, since the protruding direction of the projecting surface shape portion 82 of the foreign matter collecting filter 80 is oriented so as to incline to the downstream side in the exhaust direction, the inside of the cylindrical case portion 51 extends from the inside of the LPL-EGR pipe 71. Even if the condensed water flows backward, the condensed water flows toward the downstream side in the exhaust direction. Therefore, the PM trapping filter section 52 is rapidly cooled by the condensed water flowing backward from the inside of the LPL-EGR pipe 71 to the inside of the cylindrical case section 51, and the concern that the PM trapping filter section 52 is damaged is eliminated. When 80 is heated sufficiently on the upstream filter surface 83 side where the area is increased, formation of a water film on the foreign matter collecting filter 80 is effectively suppressed.

  Moreover, in the present embodiment, the projecting surface portion 82 of the foreign matter collecting filter 80 has an upstream filter surface 83 and a downstream filter surface 84 having different mesh sizes, and the fluid resistance in the upstream filter surface 83 is the same. However, since it is larger than the fluid resistance in the downstream filter surface 84, the condensed water flowing backward in the LPL-EGR pipe 71 toward the exhaust gas passage 42w easily flows down through the downstream filter surface 84, The exhaust gas that has passed through the PM collection filter unit 52 is likely to heat the upstream filter surface 83. Therefore, the flow of the condensed water is easily directed to the downstream side in the exhaust direction, and the upstream filter surface 83 side of the foreign matter collecting filter 80 is sufficiently heated, and the evaporation of moisture adhering to the foreign matter collecting filter 80 is promoted. .

  Further, since the mesh of the upstream filter surface 83 is finer than the mesh of the downstream filter surface 84, the posture of attaching the foreign matter collecting filter 80 to the LPL-EGR pipe 71 or the cylindrical case portion 51 is directional. However, water film formation can be suppressed while employing a simple foreign matter collecting filter 80.

  In addition, the opening position C1 where the exhaust gas passage portion 42wc on the downstream side of the exhaust gas distribution chamber 53 opens into the cylindrical case portion 51 is the position of the foreign matter collecting filter 80 from the inner wall surface 51a of the cylindrical case portion 51. Since it is located on the lower side in the vertical direction from the projecting position C2 of the projecting surface portion 82, the condensed water flowing backward from the LPL-EGR pipe 71 easily flows downstream in the exhaust direction, and the acidic condensed water is It becomes difficult to collect in the cylindrical case part 51.

  In addition, since the foreign matter collecting filter 80 is disposed with the protruding direction of the protruding surface portion 82 oriented toward the opening position of the exhaust gas passage portion 42wc downstream of the exhaust gas distribution chamber 53, the LPL-EGR pipe 71 Therefore, the condensed water flowing back into the cylindrical case portion 51 is easily discharged downstream in the exhaust direction.

  Furthermore, in this embodiment, the cylindrical case part 51 has the cone-shaped part 51c which forms the exhaust-gas distribution chamber 53 in the exit 52e side of PM collection filter part 52, and the exit 52e of PM collection filter part 52 The flow of exhaust gas entering the exhaust gas distribution chamber 53 from the projecting position C2 toward the projecting position C2 is folded along the cone-shaped portion 51c of the cylindrical case portion 51 from the projecting position C2 to the opening position C1. Therefore, it is possible to easily secure the discharge path of the condensed water that has entered the cylindrical case part 51 in a path away from the outlet of the PM collection filter part 52, and the cone-shaped part 51c is a cylinder around the PM collection filter part 52. Thus, the cylindrical case 51 of the exhaust pipe 42 can be easily separated and separated from the wall 51b, and the exhaust pipe structure can be easily assembled and maintained.

  Thus, according to the exhaust gas recirculation device for an internal combustion engine of the present embodiment, the foreign matter collecting filter 80 is provided with the projecting surface shape portion 82 projecting into the cylindrical case portion 51 and the projecting direction is exhausted. Since the LPL-EGR valve 72 is closed and the recirculated exhaust gas does not flow into the low-pressure side exhaust recirculation passage P2 while the LPL-EGR valve 72 is closed, the foreign matter collecting filter 80 is projected on the projecting surface. It can always be exposed to the exhaust gas passing through the exhaust gas passage 42w in a relatively wide area on the side of the shape portion 82, and can be sufficiently heated on the upstream filter surface 83 side where the area is widened. Even if the condensed water flows backward from the inside of the LPL-EGR pipe 71 to the inside of the cylindrical case portion 51, the flow of the condensed water can be accurately directed downstream in the exhaust direction. As a result, it is possible to effectively suppress the formation of a water film on the fine foreign matter collecting filter 80 that prevents entry of foreign matters into the recirculated exhaust gas, and the PM collecting filter unit 52 is caused to flow back by the condensed water. It is possible to provide an exhaust gas recirculation device for an internal combustion engine that can reliably prevent problems such as rapid cooling and damage.

  FIGS. 5A and 5B show a plurality of modifications of the foreign matter collecting filter in the exhaust gas recirculation device for an internal combustion engine according to the embodiment of the present invention.

  The foreign matter collecting filter 80M1 shown in FIG. 5A has a substantially frustoconical protruding surface shape portion 82, and the protruding surface shape portion 82 faces the upstream portion of the exhaust gas passage 42w. An upstream filter surface 83 disposed, and a downstream filter surface 84 disposed so as to face the downstream portion of the exhaust gas passage and to be biased downward in the vertical direction from the upstream filter surface 83. Are made of metal mesh materials having different mesh sizes and are coupled to each other.

  Alternatively, the protruding surface shape portion 82 of the foreign matter collecting filter 80 is made of the same mesh material so that the mesh material overlaps at a part of the substantially truncated cone shape, and the upstream filter surface 83 with a fine mesh at the overlapping portion. The downstream filter surface 84 having a large mesh may be formed in the single layer portion. Of course, the upstream filter surface 83 may be configured by stacking different mesh materials, or the mesh of the mesh material may be partially blocked within the formation range of the upstream filter surface 83. Needless to say, the mesh may be a slit or the like.

  The foreign matter collecting filter 80M2 shown in FIG. 5B has a substantially conical protruding surface that protrudes into the exhaust gas distribution chamber 53 from a vertical wall surface 51d provided in a part of the cone-shaped portion 51c of the cylindrical case portion 51. It has a shape portion 82, and the projecting surface shape portion 82 is formed on the upstream filter surface 83 having a large area facing the upstream portion of the exhaust gas passage 42 w and the downstream portion of the exhaust gas passage. And a downstream-side filter surface 84 having a narrow area disposed on the lower side in the vertical direction from the upstream-side filter surface 83. Here, the upstream filter surface 83 is composed of a mesh material with a fine mesh, and the downstream filter surface 84 is composed of a mesh material with a large mesh.

  Even when the foreign matter collecting filters 80M1 and 80M2 having such a modification are used, the above-described operation and effect can be expected.

  In any of the foreign matter collecting filters 80M1 and 80M2 shown in FIGS. 5A and 5B, the projecting surface shape portion 82 may have a pyramid shape, a hemispherical shape, or the like as a whole.

  In the above-described embodiment, the upstream end portion 71u of the LPL-EGR pipe 71 may have a flange portion joined to the peripheral portion of the opening of the cone-shaped portion 51c of the cylindrical case portion 51. The cylindrical case portion 51 may have a case-side flange portion that protrudes outward from a portion of the cone-shaped portion 51c and is coupled to the upstream end portion 71u of the LPL-EGR pipe 71 at the tip portion thereof. .

  In this embodiment, when connecting the LPL-EGR pipe 71 to the cylindrical case part 51, it arrange | positions so that the cyclic | annular base end part 81 of the foreign material collection filter 80 may be pinched | interposed between both (between both flange parts). Just do it. Alternatively, the annular base end portion 81 of the foreign matter collection filter 80 may be fixed to the upstream end portion 71u of the LPL-EGR pipe 71 in advance, or the annular base end portion 81 of the foreign matter collection filter 80 may be attached to the cylindrical case. The portion 51 may be fixed to the inner wall surface 51a side in advance by welding or the like. In any case, the foreign matter collecting filter 80 has the projecting surface shape portion 82 that protrudes into the exhaust gas distribution chamber 53, thereby allowing the exhaust gas flowing into the LPL-EGR pipe 71 to pass through with a wide gas passage area. be able to. The annular base end portion 81 may function as a gasket. Needless to say, the convex shape of the foreign matter collecting filter is not limited to a substantially conical shape, a hemispherical shape, a frustum shape, or the like.

  As described above, the exhaust gas recirculation device for an internal combustion engine according to the present invention is provided with the protruding surface shape portion protruding inside the cylindrical case portion on the foreign matter collecting filter, and the protruding direction is set downstream in the exhaust direction. Since it is oriented so as to incline, even when the recirculated exhaust gas does not flow into the exhaust gas recirculation passage, the foreign matter collecting filter is placed in the exhaust gas passing through the exhaust gas passage with a relatively large area on the projecting shape side. Even if it can always be exposed, it can be heated sufficiently on the upstream filter surface side where the area becomes wide, and even if the condensed water flows backward from the inside of the exhaust recirculation pipe to the inside of the cylindrical case part, The flow of the condensed water can be directed downstream in the exhaust direction, and as a result, the formation of a water film on the foreign matter collecting filter that prevents foreign matter from entering the recirculated exhaust gas is effectively suppressed. Together with An exhaust gas recirculation device for an internal combustion engine that can reliably prevent damage to a purification device or the like can be provided, and an exhaust gas recirculation for an internal combustion engine provided with a foreign matter collecting filter in the exhaust gas recirculation path Useful for all devices.

10 engine (diesel engine, internal combustion engine)
15 Turbocharger 15a Intake air compressor 15b Exhaust turbine 16 HPL-EGR device (high pressure EGR device)
17 LPL-EGR device (low pressure EGR device)
32 Intake pipe 32 w Intake passage 32 wa Upstream intake passage portion 32 wb Downstream intake passage portion 42 Exhaust pipe 42 w Exhaust gas passage 42 wa Upstream exhaust gas passage portion 42 wb Low pressure exhaust gas passage portion 42 wc Downstream exhaust gas passage portion 43 Exhaust throttle valve 51 Cylindrical case part 51a Inner wall surface 51b Cylindrical wall part 51c Cone-shaped part 51d Vertical wall surface 52 PM collection filter part (exhaust gas purification unit)
53 Exhaust gas distribution chamber (specific passage part)
71 LPL-EGR pipe (exhaust gas recirculation pipe)
72 LPL-EGR valve (exhaust gas recirculation control valve)
73 LPL-EGR cooler (exhaust cooler)
80, 80M1, 80M2 Foreign matter collecting filter 81 Annular base end portion 82 Projecting surface shape portion 83 Upstream filter surface 84 Downstream filter surface C1 Opening position C2 Protruding position P2 Low pressure side exhaust recirculation passage

Claims (6)

An exhaust pipe that forms an exhaust gas passage through which the exhaust gas of the internal combustion engine passes and has a cylindrical case portion that houses an exhaust purification unit in the middle of the exhaust gas passage;
An exhaust gas recirculation pipe for recirculating the exhaust gas from a specific passage portion of the exhaust gas passage to the intake passage side of the internal combustion engine;
An exhaust gas recirculation of an internal combustion engine, which is mounted near an upstream end portion of the exhaust gas recirculation pipe and includes a foreign material collecting filter that collects foreign material in exhaust gas recirculated from the specific passage portion to the intake passage side. A device,
The specific passage portion is formed by an internal space downstream of the exhaust purification unit in the cylindrical case portion,
The foreign matter collecting filter has a protruding surface shape portion protruding from the inner wall surface of the cylindrical case portion toward the internal space, and a protruding direction of the protruding surface shape portion is inclined downstream of the exhaust gas passage. An exhaust gas recirculation device for an internal combustion engine, characterized in that The projecting surface shape portion of the foreign matter collecting filter is disposed to face an upstream filter surface disposed facing an upstream portion of the exhaust gas passage and a downstream portion of the exhaust gas passage. A downstream filter surface disposed so as to be biased downward in the vertical direction from the upstream filter surface;
2. The exhaust of the internal combustion engine according to claim 1, wherein a fluid resistance of the foreign matter collecting filter on the upstream filter surface is larger than a fluid resistance of the foreign matter collecting filter on the downstream filter surface. Recirculation device.   The exhaust gas recirculation of the internal combustion engine according to claim 2, wherein a mesh of the foreign matter collecting filter on the upstream filter surface is finer than a mesh of the foreign matter collecting filter on the downstream filter surface. apparatus.   The opening position where the exhaust gas passage portion on the downstream side of the specific passage portion opens into the cylindrical case portion is the protrusion of the protruding shape portion of the foreign matter collecting filter from the inner wall surface of the cylindrical case portion. The exhaust gas recirculation device for an internal combustion engine according to any one of claims 1 to 3, wherein the exhaust gas recirculation device is located on a lower side in a vertical direction than the position.   The said foreign material collection filter is arrange | positioned with the protrusion direction of the said protrusion-shaped part being orient | assigned to the opening position of the exhaust-gas channel | path part downstream from the said specific channel | path part. An exhaust gas recirculation device for an internal combustion engine. The cylindrical case portion has a cone-shaped portion that forms the specific passage portion on the outlet side of the exhaust purification unit,
The flow of the exhaust gas that enters the specific passage portion from the outlet of the exhaust purification unit toward the protruding position side is from the protruding position side to the opening position side along the cone-shaped portion of the cylindrical case portion. The exhaust gas recirculation device for an internal combustion engine according to claim 5, wherein the exhaust gas recirculation device is folded back toward the engine.

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