JP2012229677A - Supercharger of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supercharger that prevents damage to a compressor wheel caused by collision of condensed water to an impeller while suppressing a reduction in the efficiency of supercharging due to pressure loss.SOLUTION: In the supercharger of an internal combustion engine, an exhaust reflux passage 63 for refluxing some of an exhaust gas into a specific section 32t of an intake passage is open at an inlet 67 of a compressor housing 66. A clearance C between an inner peripheral wall surface 66w of the compressor housing 66 and an outer edge surface 62e of a plurality of blades 62 adjacent to the inner peripheral wall surface 66w is greater at an upstream part C1 of the clearance positioned near an upstream end 62a of the blade 62 than a downstream part C2 of the clearance positioned on a side of a downstream end 62b of the blade 62. At the inlet 67, a guide member 64 is disposed for guiding the exhaust gas refluxing from the exhaust reflux passage 63 into the specific section 32t.

Description

  The present invention relates to a supercharging device for an internal combustion engine, and more particularly, to a supercharging device for an internal combustion engine that is suitable for supercharging air together with a recirculated exhaust gas that is incorporated in an exhaust gas recirculation path from the internal combustion engine.

  A turbocharger is known as a turbocharger equipped in an internal combustion engine for a vehicle. This turbo-type supercharging device rotates the turbine wheel using the exhaust energy of the internal combustion engine, thereby rotating the centrifugal compressor wheel directly connected thereto and supercharging the air to the internal combustion engine. Yes.

  Moreover, many internal combustion engines for vehicles are equipped with an EGR (exhaust gas recirculation) system that performs exhaust gas recirculation that is effective in reducing NOx (nitrogen oxides), and pass through an exhaust aftertreatment device. After that, an apparatus equipped with an LPL (low-pressure loop) -EGR circuit that enables a large amount of exhaust gas to be recirculated by returning the exhaust gas to the upstream side of the compressor of the turbocharger has begun to spread.

  In such an internal combustion engine, the water vapor in the exhaust gas recirculated to the intake passage side is cooled below its dew point temperature, so that acidic condensed water is likely to be generated. Ingenuity to prevent is made.

  For example, the EGR passage is opened in the shroud portion downstream of the throat where the air pressure is reduced around the compressor wheel to ensure the differential pressure across the EGR passage, and the EGR gas is supplied to the impeller of the compressor wheel. There is one that prevents droplet erosion and damage at the upstream end edge (for example, see Patent Document 1).

  Further, as described above, an EGR passage is opened in the shroud portion, and an exhaust gas recirculation chamber extending in the circumferential direction of the compressor wheel and a communication passage extending in a radial direction from the exhaust gas recirculation chamber and opening in the shroud portion are provided. What is provided with the resin-made shroud pieces formed is known (for example, refer patent document 2).

  Further, as a means for generating a swirling flow in the gas in the intake passage, there is known a device in which a sub intake passage that branches off from the main intake passage and merges again on the intake port side is provided (for example, see Patent Document 3).

  There is also known an arrangement in which the opening of the EGR gas introduction pipe is arranged at the center of the intake passage so that foreign matter and droplets do not collide with the impeller of the turbocharger (for example, see Patent Document 4).

JP 2008-309125 A JP 2010-168915 A JP 2010-077783 A JP 2009-024692 A

  As described above, in the conventional supercharging device for an internal combustion engine in which the EGR passage is opened in the shroud portion downstream from the throat portion of the supercharging passage, droplet erosion of the upstream end edge of the impeller due to condensed water is performed. As a result, the EGR gas can be introduced without closing the intake throttle valve or the exhaust throttle valve, and the reduction in engine efficiency can be suppressed. However, since condensed water flows toward the outer edge surface (shroud surface) of the impeller and collides with the outer edge portion of the impeller portion of the compressor wheel, there is a concern about erosion and damage of the impeller.

  Further, in a conventional supercharging device for an internal combustion engine provided with means for generating a swirling flow in the gas in the intake passage, not only the gas-liquid separation performance by the swirling flow can be sufficiently exhibited when the intake air flow rate is small. Since the space for generating the swirling flow becomes large, it is difficult to suppress the mounting space.

  On the other hand, in the conventional supercharging device for an internal combustion engine in which the opening of the EGR gas introduction pipe is arranged at the center of the intake passage, the pressure loss in the intake passage is increased by the EGR gas introduction pipe, and the supercharging of the compressor Efficiency will decrease.

  The present invention has been made in order to solve the above-described conventional problems, and prevents damage to the compressor wheel due to collision of the condensed water with the impeller portion while suppressing reduction in supercharging efficiency due to pressure loss. A supercharging device that can be used is provided.

  In order to solve the above-described problems, a supercharging device for an internal combustion engine according to the present invention includes: (1) a compressor housing that forms a specific section in an intake passage of the internal combustion engine, and a plurality of blades disposed inside the compressor housing. The compressor housing has an inlet portion for introducing air, a shroud portion surrounding the outer edges of the plurality of blades of the compressor wheel on the downstream side of the inlet portion, and the shroud portion. A turbocharger for an internal combustion engine having a diffuser portion located on the downstream side, and an exhaust gas recirculation passage for recirculating a part of the exhaust gas of the internal combustion engine into the specific section in the inlet portion An inner peripheral wall surface of the compressor housing and the compressor housing adjacent to the inner peripheral wall surface. The clearance between the blade and the outer edge surface of the blade is larger at the upstream portion located near the upstream end of the blade than the downstream portion located at the downstream end of the blade. The inlet portion of the compressor housing is provided with a guide member for guiding the exhaust gas recirculated from the exhaust gas recirculation passage into the specific section into the clearance.

  With this configuration, when the exhaust gas recirculates from the exhaust gas recirculation passage into a specific section of the intake air passage, the exhaust gas is guided to the clearance between the inner peripheral wall surface of the compressor housing and the outer edge surface of the blade of the compressor wheel by the guide member. The At this time, even if condensed water is generated from the water in the recirculated exhaust gas and flows into a specific section of the intake passage, the upstream portion of the clearance is larger than the downstream portion and the guide member The guiding action prevents condensed water having a large droplet diameter from colliding with the vicinity of the upstream end of the blades of the compressor wheel. Further, since the clearance is increased in the vicinity of the upstream end portion of the blade of the compressor wheel, the intake resistance is also suppressed. Therefore, the turbocharger can prevent the compressor wheel from being damaged by the collision of the condensed water with the impeller portion while suppressing the decrease in the supercharging efficiency due to the pressure loss.

  In the supercharging device for an internal combustion engine according to the present invention, (2) the compressor wheel has an inducer portion that introduces air through the inlet portion of the compressor housing, and the clearance is the inlet of the compressor wheel. It is preferable that it is larger as it is closer to the upstream end of the blade around the deducer.

  With this configuration, even if condensed water flows into a specific section of the intake passage and enters the clearance, the droplet diameter of the condensed water is reduced around the inducer part of the compressor wheel that starts to accelerate by introducing the intake air. When the droplet reaches the downstream end side of the blade, the droplet diameter of the condensed water becomes sufficiently small, so that damage to the compressor wheel due to the collision of the condensed water is effectively prevented. Moreover, it is possible to sufficiently increase the air flow velocity in the vicinity of the downstream side of the inducer part while reducing the intake resistance in the vicinity of the upstream part of the inducer part.

  In the supercharging device for an internal combustion engine of the present invention, (3) the guide member has a substantially cylindrical annular guide portion that is close to the upstream end portion of the blade of the compressor wheel on the downstream end side, and the inlet It is preferable that an annular passage that communicates with the clearance and communicates with the exhaust gas recirculation passage is formed between an inner circumferential wall surface of the portion and an outer circumferential surface of the annular guide portion.

  With this configuration, even if condensed water flows from the exhaust gas recirculation passage into a specific section of the intake passage, the condensed water is dispersed in the circumferential direction together with the air passing through the substantially cylindrical annular passage, and the droplet diameter is reduced. Even if the clearance in the upstream portion is not so large, the required recirculation exhaust gas introduction passage cross-sectional area can be secured.

  In the supercharging device for an internal combustion engine having the configuration of (3) above, (4) a radius between the inner peripheral surface of the annular guide portion of the guide member and the outer edge surface of the blade in the vicinity of the upstream end portion of the blade. It is preferable that the distance in the direction is set to be substantially equal to the downstream portion located on the downstream end side of the blade in the clearance. With this configuration, air is reliably introduced into the compressor wheel from the inlet portion inside the annular guide portion of the guide member, and good supercharging efficiency is obtained.

  In the supercharging device for an internal combustion engine having the configuration of (4), (5) the inner portion of the shroud portion or the inlet portion in the vicinity of the outer peripheral surface of the annular guide portion of the guide member and the upstream end portion of the blade. It is preferable that a radial distance from the peripheral wall surface is set wider than the downstream portion of the clearance. With this configuration, not only is the recirculation exhaust gas introduction passage cross-sectional area secured outside the annular guide portion, but also the loss of intake air pressure due to the annular guide portion is suppressed.

  In the supercharging device for an internal combustion engine having the configuration of (2) above, (6) the direction of introduction of the exhaust gas from the exhaust gas recirculation passage into a specific section of the intake passage is in the direction of rotation of the compressor wheel It is preferable that it is attached. With this configuration, the recirculated exhaust gas flowing into the specific section of the intake passage from the exhaust recirculation passage is guided in the clearance around the inducer while flowing in the rotation direction of the compressor wheel, and is efficiently introduced to the compressor wheel side. The Further, even if condensed water flows together with the recirculated exhaust gas, it is effectively diffused by the air flowing in the rotation direction of the compressor wheel, and the droplet diameter is reduced.

  In the supercharging device for an internal combustion engine having the configuration of (2) or (6) above, (7) an inner peripheral wall surface of the inlet portion so that the exhaust gas recirculation passage is spaced apart from the inducer portion of the compressor wheel. It is preferable to open in an annular shape over the entire circumference. With this configuration, the recirculated exhaust gas flowing into the specific section of the intake passage from the exhaust recirculation passage is guided evenly throughout the rotation direction of the compressor wheel and is guided into the clearance around the inducer portion. Efficiently introduced to the side.

  In the supercharging device for an internal combustion engine having any one of the constitutions (3) to (5), (8) the annular guide portion of the guide member has the exhaust gas recirculation passage on the inner peripheral wall surface of the inlet portion. It is desirable that the inlet portion is supported upstream of the opening range. With this configuration, the flow of the recirculated exhaust gas flowing into the specific section of the intake passage from the exhaust recirculation passage is not blocked or hindered by the support portion of the annular guide portion, and is efficiently introduced to the compressor wheel side. .

  According to the present invention, when the exhaust gas recirculates from the exhaust gas recirculation passage into the specific section of the intake air passage, the exhaust gas is guided to the clearance between the inner peripheral wall surface of the compressor housing and the outer edge surface of the blade of the compressor wheel by the guide member. Guided. At this time, even if condensed water is generated from the water in the recirculated exhaust gas and flows into a specific section of the intake passage, the upstream portion of the clearance is larger than the downstream portion and the guide member The guiding action prevents condensed water having a large droplet diameter from colliding with the vicinity of the upstream end of the blades of the compressor wheel. Further, since the clearance is increased in the vicinity of the upstream end portion of the blade of the compressor wheel, the intake resistance is also suppressed. Therefore, it is possible to provide a supercharging device that can prevent damage to the compressor wheel due to a collision with the impeller portion of condensed water while suppressing a decrease in supercharging efficiency due to pressure loss.

It is a half sectional view of the principal part of the supercharging device of the internal combustion engine which concerns on one Embodiment of this invention. 1 is a local cross-sectional view of a vicinity of a compressor wheel and a turbine wheel in a supercharging device for an internal combustion engine according to an embodiment of the present invention. 1 is a schematic system configuration diagram of an internal combustion engine according to an embodiment of the present invention. It is BB sectional drawing of FIG. It is a partial expanded sectional view of the vicinity of the guide member in the supercharging device of the internal combustion engine which concerns on one Embodiment of this invention. FIG. 3 is a graph for explaining a setting condition of a clearance between an inner peripheral wall surface of a compressor housing and an outer edge surface of a blade of a compressor wheel in a supercharging device for an internal combustion engine according to an embodiment of the present invention, and a vertical axis indicates a large clearance. The horizontal axis represents the position in the passage length direction in the range from the upstream end to the downstream end of the blade.

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

  FIGS. 1-6 is a figure which shows the supercharging device of the internal combustion engine which concerns on one Embodiment of this invention. In the present embodiment, the present invention is applied to a turbocharger equipped in a vehicle internal combustion engine, for example, an in-line four-cylinder diesel engine (hereinafter simply referred to as an engine).

  First, the schematic system configuration of the internal combustion engine of the present embodiment and the schematic configuration of the turbocharger will be described with reference to FIGS. 2 and 3.

  As shown in FIG. 3, the engine 1 of the present embodiment has a plurality of cylinders 1c in a main body block 1M. The engine 1 includes combustion chambers (not shown in detail) in each cylinder 1c. ) Is equipped with a common rail fuel injection device 2 for injecting fuel. Further, the engine 1 includes an intake device 3 that sucks air into the combustion chamber, an exhaust device 4 that exhausts exhaust gas from the combustion chamber, and an intake device 3 that uses exhaust energy in the exhaust device 4 to suck in the exhaust gas. A turbo-type supercharging device 5 that compresses air and supercharges air into the combustion chamber, and an LPL-EGR device that recirculates a part of the exhaust gas downstream from the turbo-type supercharging device 5 to the intake side for recirculation. 8 (low pressure EGR device).

  The fuel injection device 2 includes a supply pump (not shown) 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 21 into which fuel from the supply pump is introduced, A fuel injection valve 22 for injecting fuel supplied through the common rail 21 into the combustion chamber at a timing and opening degree (duty ratio) corresponding to an injection command signal from an electronic control unit (control device; hereinafter referred to as ECU) (not shown); It is comprised including. The supply pump is driven using, for example, the rotational power of the engine 1, and the common rail 21 distributes and supplies the high-pressure fuel supplied from the supply pump to the plurality of fuel injection valves 22 while maintaining a uniform pressure. The fuel injection valve 22 is composed of a known needle valve that is electromagnetically driven, and burns an amount of fuel (for example, light oil) according to the injection command signal by controlling the valve opening time according to the injection command signal. Can be injected and supplied indoors.

  The intake device 3 includes an intake manifold 31, an intake pipe 32 upstream of 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 supercharging by the turbo-type supercharger 5. An intercooler 34 (cooler) that cools the supercharged air heated by the compression in the intake pipe portion 32b on the downstream side of the turbocharger 5 is mounted.

  The exhaust device 4 is mounted on an exhaust manifold 41, an exhaust pipe 42 on the downstream side thereof, a known fuel addition valve 43 mounted on the exhaust manifold 41, and an exhaust pipe 42 on the downstream side of the turbocharger 5. And an exhaust purification unit 44 including a known oxidation catalyst 44a and a DPF (diesel particulate filter) 44b.

  The turbocharger 5 includes an intake air compressor 6 and an exhaust turbine 7 that are integrally coupled to each other in the rotational direction. The exhaust turbo compressor 7 is rotated by the exhaust energy and the intake air compressor 6 is rotated, whereby the intake air compressor 6 is rotated. The intake air is compressed by the air compressor 6 so that positive pressure air can be supplied into the engine 1.

  As shown in FIG. 2, the turbocharger 5 includes a turbine shaft 51, a compressor wheel 61 that is integrally connected to the left end of the turbine shaft 51 in FIG. A turbine wheel 71 that is integrally connected to one end side of the shaft 51 (right end side in FIG. 2) and is driven to rotate by exhaust of the engine 1 (not shown), and a center housing 56 that rotatably supports the turbine shaft 51 (Not shown), a compressor housing 66 connected to the center housing 56 to house the compressor wheel 61 and forming a specific section 32t of the intake passage 32w in the intake pipe 32, and a turbine wheel 71 connected to the center housing 56. And a turbine that forms a nozzle type exhaust passage 76n. It includes a housing 76, a.

  Here, the center housing 56, the compressor housing 66, and the turbine housing 76 constitute a turbo body 5 </ b> M that is a housing of the turbocharger 5. Further, the turbine shaft 51 rotates integrally with the turbine wheel 71 when the turbine wheel 71 is rotationally driven by the exhaust energy from the nozzle type exhaust passage 76n shown in FIG. The compressor wheel 61 is rotated by the rotation, and the engine 1 is supercharged with air.

  A plurality of bearings for rotatably supporting the turbine shaft 51, such as a pair of floating bush bearings, are mounted at the center of the center housing 56 through which the turbine shaft 51 passes.

  As shown in FIG. 1, the compressor housing 66 includes an inlet portion 67 that introduces air sucked into the engine 1, and a shroud portion 68 that surrounds the plurality of blades 62 of the compressor wheel 61 on the downstream side of the inlet portion 67 from the outside. And a diffuser portion 69 located on the downstream side of the shroud portion 68.

  The compressor wheel 61 constitutes an inducer portion 61i that introduces air through the inlet portion 67 of the compressor housing 66 in the vicinity of the upstream end portion 62a of the plurality of blades 62, and a plurality of components constituting the inducer portion 61i. The outer edge surface 62e in the vicinity of the upstream end portion 62a of the blade 62 is located on a virtual substantially cylindrical surface rotated around the axis of the compressor wheel 61 with a straight line or a gently curved curve as a generating line.

  The specific section 32t of the intake passage 32w formed inside the compressor housing 66 includes an upstream-side passage portion 66a positioned inside the inlet portion 67 upstream of the upstream end portions 62a of the plurality of blades 62, and the upstream-side passage. The compressor wheel 61 and the shroud portion 68 radiate outward from the center of the upstream passage portion 66a on the downstream side of the portion 66a and within the range from the upstream end portion 62a to the downstream end portion 62b of the plurality of blades 62. The curved intermediate passage portion 66b and a diffuser passage portion 66c on the downstream side of the intermediate passage portion 66b (on the downstream side of the downstream end portions 62b of the plurality of blades 62) are configured.

  Here, the diffuser passage portion 66c on the downstream side of the compressor wheel 61 is a substantially annular plate-like passage that surrounds the compressor wheel 61 and intersects the turbine shaft 51 at a predetermined angle (for example, orthogonal). . The diffuser passage portion 66c is connected to the intake pipe portion 32b on the intercooler 34 side at the downstream end of the spiral passage 66d connected to the outer peripheral portion thereof.

  As shown in FIG. 2, the nozzle-type exhaust passage 76n of the exhaust turbine 7 communicates with the exhaust passage in the exhaust manifold 41 at the upstream side passage portion 76a, and the exhaust gas from the exhaust manifold 41 flows in. The nozzle type exhaust passage 76n has a nozzle passage portion 76b that is curved radially inward from the upstream passage portion 76a toward the turbine wheel 71, and is accelerated through the nozzle passage portion 76b. The turbine wheel 71 is driven by the exhaust gas. A passage portion 76 c downstream from the turbine wheel 71 communicates with the inside of the oxidation catalyst 44 a of the exhaust purification unit 44.

  As shown in FIG. 3, the LPL-EGR apparatus 8 includes an LPL-EGR pipe 81 (low-pressure side exhaust recirculation pipe) interposed between the exhaust pipe 42 and the intake pipe 32, and the LPL-EGR pipe 81. The LPL-EGR valve 82 (low pressure EGR valve) that is mounted in the middle and can adjust the recirculation amount of the exhaust gas, and the exhaust gas passing through the LPL-EGR pipe 81 are exchanged with cooling water or the like in the middle. An LPL-EGR cooler 83 as an exhaust cooler that can be cooled, and an exhaust passage 42w in the exhaust pipe 42 on the downstream side are opened so that the passage cross-sectional area is reduced in the passage portion downstream of the exhaust purification unit 44. And an exhaust throttle valve (not shown) capable of reducing the degree.

  The LPL-EGR device 8 includes an LPL-EGR pipe 81 and an upstream side intake pipe 42b upstream of the intake air compressor 6 in the intake pipe 32 and a downstream side exhaust pipe portion 42b downstream of the exhaust turbine 7 in the exhaust pipe 42. The exhaust part 7a is connected to be communicable, and the exhaust turbine 7 and the exhaust purification unit 44 are used as resistance elements so that the low-pressure side exhaust gas having a low pressure downstream can be recirculated into the upstream side intake pipe part 32a. It has become. Further, the LPL-EGR device 8 sucks the recirculated exhaust gas from the inlet side of the intake air compressor 6.

  Specifically, the LPL-EGR pipe 81 has a position where the intake pipe 32 and the LPL-EGR pipe 81 downstream of the position J1 where the LPL-EGR pipe 81 is connected to the intake pipe 32 are connected to the exhaust pipe 42. A low-pressure side exhaust recirculation path for recirculating the low-pressure side exhaust gas in the engine 1 is formed together with the exhaust pipe 42 upstream from J2, and the low-pressure side exhaust forming the main part of the low-pressure side exhaust recirculation path is formed therein. A reflux passage 81w is formed.

  The LPL-EGR valve 82 is arranged between the LPL-EGR cooler 83 and the upstream side intake pipe portion 32a of the intake pipe 32 and controls the recirculation amount of the low-pressure side exhaust gas, and can be opened and closed and the opening thereof can be controlled. Thus, it is possible to switch between a valve-opening state in which the low-pressure side exhaust gas recirculation passage 81w is opened and a valve-closing state in which the opening of the low-pressure side exhaust gas recirculation passage 81w is restricted (for example, blocked).

  Although not shown in detail, the LPL-EGR cooler 83 has a gas pipe part that forms a part of the low-pressure side exhaust recirculation passage 81w, and a housing part that forms a cooling fluid passage around the gas pipe part. The low-pressure side recirculation exhaust gas is obtained by heat exchange between the cooling fluid (for example, cooling water) introduced into the housing portion and the recirculation exhaust gas passing through a part of the low-pressure side exhaust recirculation passage 81w in the gas pipe portion. The gas can be cooled.

  As described above, in the intake air compressor 6 of the turbocharger 5 installed in the engine 1, the compressor wheel 61 is disposed inside the compressor housing 66 that forms the specific section 32 t in the intake passage 32 w of the engine 1. The compressor wheel 61 is arranged so as to be rotatable, and as it rotates, the compressor wheel 61 performs a centrifugal compression action on the air between the plurality of blades 62, and the air in the specific section 32 t of the intake passage 32 w is supplied to the downstream side. It gives kinetic energy that accelerates the movement.

  This compressor wheel 61 comprises an impeller portion 61p by mounting a hub portion 61h integrally connected to the turbine shaft 51 and a plurality of blades 62 at equal angular intervals on one side of the hub portion 61h. is there.

  In the wall of the inlet 67 of the compressor housing 66, as shown in FIG. 4, an exhaust gas recirculation passage 63 that recirculates a part of the exhaust gas of the engine 1 from the low pressure side exhaust gas recirculation passage 81w into the specific section 32t is substantially circular. It is formed in an annular shape.

  As shown in FIGS. 1 and 4, the exhaust gas recirculation passage 63 includes a connection passage portion 63a connected to the low pressure side exhaust recirculation passage 81w, and an annular passage having a substantially rectangular cross section communicating with the connection passage portion 63a. The portion 63b and an annular communication passage 63c that extends radially inward from the annular passage portion 63b and communicates the annular passage portion 63b and the specific section 32t of the intake passage 32w.

  In the exhaust gas recirculation passage 63, the connecting passage portion 63a extends in the tangential direction of the annular passage portion 63b, so that the introduction direction of the exhaust gas from the exhaust gas recirculation passage 63 into the specific section 32t of the intake passage 32w is the compressor wheel 61. The direction toward the inducer portion 61 i of the compressor wheel 61 is directed to the rotation direction of the compressor wheel 61. Further, the annular communication passage 63 c of the exhaust gas recirculation passage 63 is located upstream from the upstream end portion 62 a of the plurality of blades 62 of the compressor wheel 61 and toward the central portion of the inlet portion 67 over the entire inner periphery of the inlet portion 67. Opening with an opening width w. That is, the exhaust gas recirculation passage 63 is opened in an annular shape extending over the entire circumference of the inner peripheral wall surface 66 w of the inlet portion 67 so as to be spaced from the inducer portion 61 i of the compressor wheel 61 by a certain axial distance. The direction of the communication path 63c is a direction orthogonal to the rotation center axis of the compressor wheel 61 in the drawing, but may be inclined with respect to this direction.

  An annular clearance C between the inner peripheral wall surface 66w of the compressor housing 66 and the outer edge surface 62e of the plurality of blades 62 of the compressor wheel 61 adjacent to the inner peripheral wall surface 66w is provided on the downstream end 62b side of the plurality of blades 62. The upstream portion C1 located in the vicinity of the upstream ends 62a of the plurality of blades 62 is larger than the downstream portion C2 that is positioned.

  Specifically, the clearance C is around the inducer portion 61i that is the air introduction portion of the compressor wheel 61, that is, from the upstream end portion 62a of the plurality of blades 62 constituting the inducer portion 61i to the vicinity of the intermediate portion 62c. Within the axial range, as shown in FIG. 6, the upstream portion C <b> 1 changes so as to increase as it approaches the upstream end portion 62 a of the plurality of blades 62. Further, the clearance C is a downstream portion C2 close to a constant gap value t2 from the intermediate portion 62c of the plurality of blades 62 to the downstream end portion 62b side.

  6, the clearance clearance value (gap value) of the downstream portion C2 slightly changes depending on the position, as indicated by a phantom line in FIG. 6, and the upstream end portions 62a to the downstream end portions of the plurality of blades 62 are changed. The clearance C may continuously change within the axial range up to the vicinity of 62b. However, in that case, the upstream axial range from the upstream end 62a of the plurality of blades 62 to the vicinity of the intermediate portion 62c in which the change rate of the clearance C (the degree of increase as the distance from the upstream ends 62a of the plurality of blades 62 increases) is increased. The rate of change is greater than the rate of change in the axial range on the downstream side. Further, such a magnitude relationship of the change rate of the clearance C is also established locally, and the clearance change rate in the upstream portion near the upstream end portion 62a of the plurality of blades 62 is the clearance change rate in the downstream portion. It always gets bigger. This means that no step is formed on the inner peripheral wall surface 66w of the compressor housing 66 that constitutes the specific section 32t of the intake passage 32w so as to rapidly decrease the inner diameter.

  On the other hand, a guide member 64 for guiding the exhaust gas recirculated from the exhaust gas recirculation passage 63 into the specific section 32t into the clearance C is provided inside the inlet portion 67 of the compressor housing 66.

  As shown in FIG. 5, the guide member 64 has a substantially cylindrical annular guide portion 64 a that is close to the upstream end portion 62 a of the impeller portion 61 p of the compressor wheel 61 on the downstream end side thereof. An annular passage 65 communicating with the clearance C and communicating with the exhaust gas recirculation passage 63 is formed between the inner circumferential wall surface 66w and the outer circumferential surface S2 of the annular guide portion 64a.

  The annular guide portion 64a of the guide member 64 is slightly larger in diameter than the tip portion of the inducer portion 61i of the compressor wheel 61, and the inner peripheral surface S1 of the annular guide portion 64a of the guide member 64 and a plurality of blades. The distance t1 in the radial direction from the outer edge surface 62e of the plurality of blades 62 in the vicinity of the upstream end portion 62a of the 62 is a clearance between the downstream portion C2 located on the downstream end portion 62b side of the plurality of blades 62 in the clearance C. It is set approximately equal to the value t2.

  Further, the radial separation distance t3 between the outer peripheral surface S2 of the annular guide portion 64a of the guide member 64 and the inner peripheral wall surface 66w of the shroud portion 68 or the inlet portion 67 in the vicinity of the upstream end portions 62a of the plurality of blades 62 is a clearance. C is set to a value larger than the gap value t2 of the downstream portion C2 (for example, a value of about 1 mm when the gap value t2 is 0.3 mm), and the plate of the annular guide portion 64a of the guide member 64 The thickness tg is set to be equal to or less than the gap value t2 of the downstream portion C2 of the clearance C. Therefore, the clearance C has an inlet opening area of the upstream portion C1 larger than the annular gap of the separation distance t3 around the annular guide portion 64a of the guide member 64 at the downstream end portion of the annular passage 65. Note that the inner peripheral wall surface 66w of the compressor housing 66 is such that the radial separation distance t3 in a specific portion on the lower side in the vertical direction of the compressor housing 66 is larger than that in the other portion (upper side). It may be set in a shape that spreads downward in the direction.

  The guide member 64 has a fitting portion 64b fitted to the inlet portion 67 of the compressor housing 66, and a plurality of column portions 64c projecting radially inward from the fitting portion 64b. The annular guide portion 64a is upstream of the range of the opening width w (see FIG. 5) in which the exhaust gas recirculation passage 63 opens to the inner peripheral wall surface 66w of the inlet portion 67, and is inserted into the inlet 64b and the column portion 64c. Supported by part 67.

  The annular guide portion 64a of the guide member 64 is concentrically supported by the inlet portion 67 via the fitting portion 64b and the column portion 64c as described above, and the inner peripheral surface S1 thereof is the upstream end of the plurality of blades 62. The outer edge surfaces 62e of the plurality of blades 62 in the vicinity of the portion 62a are separated from each other by a radial separation distance t1, and the downstream end surface 64d thereof is substantially the tip surface of the upstream end portion 62a of the plurality of blades 62 of the compressor wheel 61. It is located at the same position in the axial direction. The shift in the axial position of the downstream end surface 64d of the guide member 64 is caused by the radial separation distance t1 between the inner peripheral surface S1 of the annular guide portion 64a and the outer edge surface 62e in the vicinity of the upstream end portions 62a of the plurality of blades 62. Preferably, it is limited to a smaller range.

  Next, the operation will be described.

  In the internal combustion engine supercharging device of the present embodiment configured as described above, during operation of the engine 1, a part of the exhaust gas of the engine 1 is taken in by the LPL-EGR device 8 through the intake air of the turbo supercharging device 5. It returns to the upstream side of the compressor 6. At this time, when the recirculated exhaust gas in the low pressure side exhaust recirculation passage 81w is cooled in the vicinity of the LPL-EGR cooler 83 of the LPL-EGR device 8, and the water vapor in the recirculated exhaust gas is cooled to below the dew point temperature. Condensed water is generated, and sulfur compounds in the exhaust gas dissolve in the condensed water, which may increase the acidity of the condensed water. Therefore, the recirculated exhaust gas containing acidic condensed water can flow into the exhaust gas recirculation passage 63 that recirculates from the low pressure side exhaust gas recirculation passage 81w into the specific section 32t.

  However, in this embodiment, when the exhaust gas recirculates from the exhaust gas recirculation passage 63 into the specific section 32t of the intake air passage 32w, the exhaust gas is guided by the guide member 64 to the inner peripheral wall surface 66w of the compressor housing 66 and the plurality of compressor wheels 61. It is guided in a clearance C which is an annular space between the outer edge surface 62e of the blade 62.

  Therefore, even if condensed water is generated from the water in the recirculated exhaust gas and flows into the specific section 32t of the intake passage 32w, the upstream portion C1 of the clearance C is larger than the downstream portion C2. By the guiding action of the recirculated exhaust gas into the clearance C by the guide member 64, the condensed water having a large droplet diameter is prevented from colliding with the vicinity of the upstream ends 62a of the plurality of blades 62 of the compressor wheel 61. .

  Moreover, since the clearance C is increased in the vicinity of the upstream ends 62a of the plurality of blades 62 of the compressor wheel 61, the intake air introduction resistance in the inducer portion 61i of the compressor wheel 61, that is, the specific section 32t of the intake passage 32w. Inhalation resistance in the can also be suppressed sufficiently. Therefore, it is possible to prevent the compressor wheel 61 from being damaged due to the collision of condensed water with the impeller portion 61p composed of the plurality of blades 62 while suppressing a decrease in the supercharging efficiency of the turbocharger 5 due to pressure loss.

  Further, in the present embodiment, the clearance C becomes larger around the inducer portion 61i of the compressor wheel 61 and closer to the upstream end portion 62a of the blade 62, so that the condensed water is within the specific section 32t of the intake passage 32w. Even if it flows into the clearance C and enters the clearance C, the droplet diameter of the condensed water decreases around the inducer 61i of the compressor wheel 61 that starts to accelerate by introducing the intake air. Moreover, when the condensed water reaches the downstream end portion 62b side of the blade 62, the droplet diameter of the condensed water becomes sufficiently small, so that the compressor wheel 61 is effectively prevented from being damaged by the collision of the condensed water. Therefore, it is possible to sufficiently increase the air flow velocity near the downstream side of the inducer 61i while reducing the intake resistance near the upstream side of the inducer 61i.

  In addition, an annular passage 65 communicating with the clearance C and communicating with the exhaust recirculation passage 63 is formed between the inner peripheral wall surface 66w of the inlet portion 67 and the outer peripheral surface S2 of the annular guide portion 64a. Even if the condensed water flows from the passage 63 into the specific section 32t of the intake passage 32w, the condensed water is dispersed in the axial direction and the circumferential direction together with the air from the upstream side passing through the substantially cylindrical annular passage 65. The droplet diameter is reduced. Further, even if the upstream portion C1 of the clearance C is not so large, it is possible to secure a required recirculation exhaust gas introduction passage cross-sectional area at the downstream end portion of the annular passage 65.

  In the present embodiment, the radial separation distance t1 between the inner peripheral surface S1 of the annular guide portion 64a of the guide member 64 and the outer edge surface 62e in the vicinity of the upstream end portion 62a of the plurality of blades 62 is the blade 62 of the clearance C. Since the clearance value t2 of the downstream portion C2 located on the downstream end portion 62b side of the guide member 64 is set to be approximately equal to this, also from this point, the inlet portion 67 to the compressor wheel 61 is formed inside the annular guide portion 64a of the guide member 64. As a result, air is surely introduced to the tank, and good supercharging efficiency can be obtained.

  Further, the radial separation distance t3 between the outer peripheral surface S2 of the annular guide portion 64a of the guide member 64 and the inner peripheral wall surface 66w in the vicinity of the upstream end portion 62a of the blade 62 is the downstream portion C2 of the clearance C. Since it is set wider than the gap value t2, not only the recirculated exhaust gas introduction passage cross-sectional area is secured outside the annular guide portion 64a, but also the pressure loss due to the annular guide portion 64a is suppressed.

  Further, since the exhaust gas introduction direction from the exhaust gas recirculation passage 63 into the specific section 32t of the intake passage 32w is directed to the rotation direction of the compressor wheel 61, the exhaust gas flows from the exhaust gas recirculation path 63 into the specific section 32t. The recirculated exhaust gas is guided in the clearance C around the inducer 61 i while flowing in the rotation direction of the compressor wheel 61, and can be efficiently introduced to the compressor wheel 61 side. Further, even if condensed water flows together with the recirculated exhaust gas, the condensed water droplets are effectively diffused by the air flowing in the rotation direction of the compressor wheel 61, and the droplet diameter is reduced.

  Further, since the annular communication passage 63c of the exhaust gas recirculation passage 63 is annularly opened over the entire circumference of the inner peripheral wall surface 66w while being separated from the inducer portion 61i of the compressor wheel 61 by a predetermined distance, From this point, the recirculated exhaust gas flowing into the specific section 32t of the intake passage 32w is guided into the clearance C around the inducer portion 61i while being uniformly introduced throughout the rotation direction of the compressor wheel 61. However, the recirculated exhaust gas is efficiently introduced into the compressor wheel 61 side.

  In addition, the annular guide portion 64a of the guide member 64 is supported by the inlet portion 67 on the upstream side of the opening position of the communication passage 63c of the exhaust gas recirculation passage 63. The flow of the recirculated exhaust gas flowing in is not blocked or hindered by the support portion of the annular guide portion 64a, and is efficiently introduced into the compressor wheel 61 side.

  As described above, in the supercharging device for the internal combustion engine according to the present embodiment, when the exhaust gas recirculates from the exhaust recirculation passage 63 into the specific section 32t of the intake passage 32w, the exhaust gas flows into the compressor housing 66 by the guide member 64. Since it is guided by the clearance C between the inner peripheral wall surface 66w and the outer edge surface 62e of the blade 62 of the compressor wheel 61, condensed water is generated from the moisture in the recirculated exhaust gas, which is used to specify the intake passage 32w. Even if it flows into the section 32t, the upstream portion C1 of the clearance C is larger than the downstream portion C2, and the guide member 64 guides the recirculated exhaust gas into the clearance C. Condensed water having a large droplet diameter is prevented from colliding with the vicinity of the upstream ends 62 a of the plurality of blades 62 of the compressor wheel 61. It can be. In addition, since the clearance C is increased in the vicinity of the upstream end portion 62a of the blade 62 of the compressor wheel 61, the intake resistance can be suppressed.

  As a result, it is possible to provide the turbocharger 5 that can prevent the compressor wheel 61 from being damaged by the collision of the condensed water with the impeller portion 61p while suppressing the decrease in the supercharging efficiency due to the pressure loss.

  In the above-described embodiment, the turbocharger 5 that drives the compressor wheel 61 from the exhaust turbine 7 side has been described. However, the turbocharger of the present invention is a supercharger that uses another rotational drive source. Is also applicable. Further, the present invention exemplifies the engine 1 having only the LPL-EGR device 8 which is a low pressure EGR device, but it may be an internal combustion engine having a high pressure EGR device or an internal combustion engine having a PCV system. Nor. Moreover, although one above-mentioned embodiment was a case where this invention was applied to the diesel engine, it cannot be overemphasized that the internal combustion engine said to this invention is not limited to a diesel engine. Furthermore, the present invention is not limited to an internal combustion engine equipped with an EGR device, and in the case where other gases such as PCV gas capable of generating condensed water are compressed together with intake air by a supercharging compressor wheel. Is applicable.

  As described above, when the exhaust gas recirculates from the exhaust gas recirculation passage into a specific section of the intake air passage, the supercharging device for an internal combustion engine according to the present invention is guided by the guide member to the inner peripheral wall surface of the compressor housing. Since it is guided by the clearance between the outer peripheral surfaces of the blades of the compressor wheel, even if condensed water is generated from the moisture in the recirculated exhaust gas and flows into a specific section of the intake passage, Due to the fact that the upstream part is larger than the downstream part and the guide action of the reflux exhaust gas by the guide member, the condensed water having a large droplet diameter collides with the vicinity of the upstream end of the blade of the compressor wheel. In addition, since the clearance is increased near the upstream end of the compressor wheel blades, intake resistance can be suppressed. Can. As a result, there is an effect that it is possible to provide a supercharging device capable of preventing damage to the compressor wheel due to collision with the impeller portion of the condensed water while suppressing reduction in supercharging efficiency due to pressure loss, The present invention is useful for a general supercharging device for an internal combustion engine that is incorporated in an exhaust gas recirculation path from the internal combustion engine and supercharges air together with the recirculated exhaust gas.

1 engine (internal combustion engine, diesel engine)
5 Turbo-type supercharger (supercharger)
6 Intake air compressor (centrifugal compressor)
8 LPL-EGR equipment (low pressure EGR equipment)
32w Intake passage 32t Specific section 42w Exhaust passage 44 Exhaust purification unit 61 Compressor wheel 61h Hub portion 61i Inducer portion 61p Impeller portion 62 Blades (multiple blades)
62a upstream end portion 62b downstream end portion 62e outer edge surface 63 exhaust recirculation passage 64 guide member 64a annular guide portion 65 annular passage 66 compressor housing 66w inner peripheral wall 67 inlet portion 68 shroud portion 69 diffuser portion 81w low pressure side exhaust recirculation passage C clearance C1 Upstream part (upstream part of clearance)
C2 Downstream part (downstream part of clearance)
S1 Inner peripheral surface (inner peripheral surface of the annular guide)
S2 outer peripheral surface (the outer peripheral surface of the annular guide)
t1 Separation distance t2 Gap value in downstream portion t3 Radial separation distance

Claims (8)

A compressor housing forming a specific section of the intake passage of the internal combustion engine;
A compressor wheel having a plurality of blades disposed inside the compressor housing,
The compressor housing includes an inlet portion for introducing air; a shroud portion that surrounds an outer edge of the plurality of blades of the compressor wheel on the downstream side of the inlet portion; and a diffuser portion positioned on the downstream side of the shroud portion; And having
The supercharging device for an internal combustion engine in which an exhaust gas recirculation passage for recirculating a part of the exhaust gas of the internal combustion engine into the specific section is opened in the inlet portion,
The clearance between the inner peripheral wall surface of the compressor housing and the outer edge surface of the blade of the compressor wheel adjacent to the inner peripheral wall surface is smaller than the downstream portion of the blade located on the downstream end side of the blade. Is larger at its upstream part located near the upstream end of
A supercharging device for an internal combustion engine, characterized in that a guide member for guiding exhaust gas recirculated from the exhaust gas recirculation passage into the specific section into the clearance is provided in the inlet portion of the compressor housing. The compressor wheel has an inducer for introducing air through the inlet of the compressor housing;
2. The supercharging device for an internal combustion engine according to claim 1, wherein the clearance is larger around the inducer portion of the compressor wheel and closer to an upstream end portion of the blade. The guide member has a substantially cylindrical annular guide portion adjacent to an upstream end portion of the blade of the compressor wheel on a downstream end side;
2. An annular passage communicating with the clearance and communicating with the exhaust gas recirculation passage is formed between an inner peripheral wall surface of the inlet portion and an outer peripheral surface of the annular guide portion. Item 3. The supercharging device for an internal combustion engine according to Item 2.   A radial separation distance between the inner peripheral surface of the annular guide portion of the guide member and the outer edge surface of the blade in the vicinity of the upstream end portion of the blade is located on the downstream end side of the blade in the clearance. The supercharging device for an internal combustion engine according to claim 3, wherein the supercharging device is set to be substantially equal to the downstream portion.   A radial separation distance between the outer peripheral surface of the annular guide portion of the guide member and the inner peripheral wall surface of the shroud portion or the inlet portion in the vicinity of the upstream end portion of the blade is wider than the downstream portion of the clearance. The supercharging device for an internal combustion engine according to claim 4, wherein the supercharging device is set.   The supercharging of the internal combustion engine according to claim 2, wherein a direction of introduction of the exhaust gas from the exhaust gas recirculation passage into a specific section of the intake passage is directed to a rotation direction of the compressor wheel. apparatus.   The said exhaust gas recirculation | circulation passage is opened in the cyclic | annular form covering the perimeter of the inner peripheral wall surface of the said inlet part so that a fixed distance may be spaced apart from the said inducer part of the said compressor wheel, The Claim 2 or Claim 6 characterized by the above-mentioned. The internal combustion engine supercharging device described.   The annular guide portion of the guide member is supported by the inlet portion on the upstream side of an opening range in which the exhaust gas recirculation passage opens on the inner peripheral wall surface of the inlet portion. The supercharging device for an internal combustion engine according to any one of claims 5 to 6.

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