JP2011099375A - Exhaust reflux device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust reflux device of an internal combustion engine that can easily mount a catalyst unit in front of an exhaust cooler, and effectively reduce exhaust pulsation to suppress exhaust interference, in the internal combustion engine including two confluent exhaust passages and an exhaust turbo supercharger of a twin entry type. <P>SOLUTION: The exhaust reflux device includes: an EGR passage 51, which has a first passage 51a connected to a confluent exhaust passage 31a, a second passage 51b connected to a confluent exhaust passage 31b and a third passage 51c connected to internal space of a surge tank 27, and circulates part of exhaust gas to an intake side through the passages 51a to 51c; an EGR valve 52, of a three way valve structure, which intervenes between the first and second passages 51a and 51b, and the third passage 51c; and an EGR cooler 53 and the catalyst unit 54 which form pulsation reducing passages 53wa, 53wb, 54wa and 54wb which attenuate pulsation of exhaust gas pressure on parts of both the passages 51a and 51b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable for an exhaust gas recirculation device for an internal combustion engine, particularly for an internal combustion engine in which exhaust from a plurality of cylinders is divided into two systems and introduced into a twin entry type exhaust turbocharger so as to avoid exhaust interference. The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

  In a four-cycle multi-cylinder internal combustion engine, exhaust interference occurs when the exhaust passages (exhaust pipes) of all the cylinders are gathered near their exhaust ports. Some exhaust the exhaust gas from two cylinders so that the exhaust gases from the cylinders that are separated from each other merge. In addition, when supercharging is performed with such an engine, a twin-entry type exhaust turbocharger that can take in the exhaust gas from both combined exhaust passages without causing exhaust interference is effective. Therefore, an internal combustion engine using two combined exhaust passages and a twin entry type exhaust turbocharger has been proposed (see, for example, Patent Document 1).

  On the other hand, it is known that an exhaust gas recirculation device that recirculates a part of exhaust gas to the intake side is effective in reducing exhaust emissions and improving fuel efficiency (see, for example, Patent Document 2).

JP-A-2005-330836 JP 2006-214275 A

  However, when an exhaust gas recirculation device is equipped in an engine having the above-described two merged exhaust passages and a twin entry type exhaust turbocharger, there are the following problems.

  For example, in an engine equipped with an exhaust gas recirculation device, when it is desired to dispose an exhaust purification catalyst unit upstream of the exhaust cooler, a certain length of pipe line is required because it is necessary to suppress exhaust interference in the two combined exhaust passages. Therefore, it is not easy to mount the catalyst unit.

  On the other hand, if the length of the two merged exhaust passages is shortened, there is a concern that the residual gas increases due to exhaust interference and the engine combustion deteriorates.

  Accordingly, the present invention provides an internal combustion engine having two merged exhaust passages and a twin entry type exhaust turbocharger, in which a catalyst unit can be easily mounted in front of an exhaust cooler, and exhaust pulsation can be effectively reduced. It is an object of the present invention to provide an exhaust gas recirculation device for an internal combustion engine that can suppress interference.

  In order to achieve the above object, an exhaust gas recirculation apparatus for an internal combustion engine according to the present invention (1) exhausts exhaust gases from a plurality of cylinders whose exhaust stroke order is adjacent to each other and exhausts them separately. Twin entry having a first combined exhaust passage and a second combined exhaust passage for combining exhaust gases from the cylinders, and two nozzle passages connected to the first combined exhaust passage and the second combined exhaust passage An exhaust gas recirculation device installed in an internal combustion engine having an exhaust turbocharger of a type, wherein the first recirculation device is connected to the first combined exhaust passage, and is connected to the second combined exhaust passage And a third passage portion connected to the intake passage of the internal combustion engine, and a part of the exhaust gas of the internal combustion engine is transferred to the first passage portion, the second passage portion, and the third passage. Through the passage and through the intake passage An exhaust gas recirculation passage that can be recirculated, a three-way exhaust gas recirculation valve interposed between the first and second passage portions of the exhaust gas recirculation passage, and the exhaust gas recirculation passage. Pulsation reducing means for forming a pulsation reducing path for attenuating pulsation of the pressure of exhaust gas passing through the first passage portion and the second passage portion in a part of the first passage portion and a part of the second passage portion, respectively. And.

  With this configuration, the pulsation of the exhaust gas pressure is effectively attenuated in the first passage portion and the second passage portion, which are the exhaust gas recirculation passages from the first confluence exhaust passage and the second confluence exhaust passage to the exhaust gas recirculation valve. And exhaust interference can be effectively suppressed.

  In the exhaust gas recirculation device for an internal combustion engine of the present invention, (2) the three-way exhaust gas recirculation valve is in a valve open state in which the first passage portion, the second passage portion, and the third passage portion are in communication with each other; The first passage portion, the second passage portion, and the third passage portion are switched to a closed state in which communication between any one of them is blocked, and the pulsation reducing means is configured to be the first passage portion and the second passage portion. And an exhaust gas purification catalyst unit for purifying the exhaust gas passing through the first passage portion and the second passage portion on the upstream side of the exhaust cooler. Is preferred.

  With this configuration, even when the passage length to the exhaust purification catalyst unit is short, the pulsation of the pressure of the recirculated exhaust gas can be effectively attenuated while suppressing the pressure loss of the recirculated exhaust gas to be equal to that of the existing exhaust recirculation passage. It is possible to effectively suppress the exhaust interference when the three-way exhaust recirculation valve is opened. Further, by blocking between the first passage portion and the second passage portion when the three-way exhaust recirculation valve is closed, exhaust interference can be reliably prevented. Further, since the passage length to the exhaust purification catalyst unit can be shortened, the exhaust purification catalyst unit can be easily mounted.

  The three-way exhaust gas recirculation valve may be disposed on the upstream side (the first and second combined exhaust passage side) from the exhaust cooler, or may be disposed on the upstream side from the exhaust purification catalyst unit. However, when the three-way exhaust gas recirculation valve is arranged on the upstream side of the exhaust purification catalyst unit, the pulsation reducing means may include a part of the first passage part and a part of the second passage part with a large number of mesh-like fine details. It is preferable to include a net-like member for forming a hole passage.

  According to the present invention, in an internal combustion engine including two merged exhaust passages and a twin entry type exhaust turbocharger, a catalyst unit can be easily mounted in front of an exhaust cooler, and exhaust pulsation can be effectively reduced and exhausted. An exhaust gas recirculation device for an internal combustion engine that can suppress interference can be provided.

1 is a schematic block configuration diagram of an exhaust gas recirculation device for an internal combustion engine according to a first embodiment of the present invention. It is a principal part block diagram of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on 1st Embodiment. It is a schematic cross section which shows the form of four different pipe lines of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on 1st Embodiment. It is a schematic block block diagram of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on 2nd Embodiment of this invention. It is a principal part block diagram of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on 2nd Embodiment. (A) is a front view of the mesh-shaped channel | path formation member in the exhaust gas recirculation apparatus of the internal combustion engine which concerns on 2nd Embodiment, (b) is sectional drawing which shows an example of the installation form of the mesh-shaped channel | path formation member.

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

(First embodiment)
1 to 3 show an exhaust gas recirculation device for an internal combustion engine according to a first embodiment of the present invention.

  An engine 10 shown in FIG. 1 is a multi-cylinder internal combustion engine for vehicles, for example, a four-cylinder gasoline engine (hereinafter simply referred to as an engine), and has a plurality of cylinders 11.

  The engine 10 includes a well-known fuel injection device (not shown) that injects fuel into a combustion chamber (not shown in detail) in each cylinder 11, an intake device 12 that sucks air into the combustion chamber, and a combustion chamber. An exhaust device 13 for exhausting the exhaust gas, a twin-entry exhaust turbocharger 14 having an exhaust turbine 14T rotated by exhaust energy in the exhaust device 13 and an intake air compressor 14C rotating integrally therewith, and an exhaust gas And an exhaust gas recirculation device 15 that recirculates a part of the gas to the intake side and recirculates it. The fuel injection device supplies fuel into the combustion chamber at a timing and duty ratio corresponding to an injection command signal from a fuel pump that pumps fuel from a fuel tank (not shown) and an electronic control unit (hereinafter referred to as ECU) 30 described later. And a fuel injection valve that injects fuel.

  The intake device 12 includes an intake manifold 21, an intake pipe 22 that forms an intake passage upstream of the intake manifold 21, an air cleaner 23 that cleans intake air by a filter on the upstream side of the intake pipe 22, and an exhaust turbocharger 14, an intercooler 24 that cools the intake air heated by supercharging downstream of the intake air compressor 14 </ b> C, an air flow meter 25 that detects an intake air flow rate (fresh air intake amount), and intake air into the engine 10. A throttle valve 26 for adjusting the amount, and a surge tank 27 for suppressing pulsation of intake air on the upstream side of the intake manifold 21 are provided.

  The exhaust device 13 includes an exhaust manifold 31, an exhaust pipe 32 that forms an exhaust passage downstream of the exhaust manifold 31, and an air-fuel ratio sensor 33 that is mounted on the exhaust pipe 32 downstream of the exhaust turbine 14T of the exhaust turbocharger 14. And an exhaust aftertreatment device 34 incorporating an exhaust purification catalyst.

  Here, the exhaust manifold 31 includes a plurality of cylinders of the engine 10 whose exhaust periods (exhaust stroke order) are separated from each other, such as an exhaust port, for example, a first cylinder and a fourth cylinder (# in FIG. 1). 1 and # 4), the first merged exhaust passage 31a connected to the exhaust port (not shown), and the exhaust ports of the remaining cylinders whose exhaust periods are separated from each other among the plurality of cylinders of the engine 10, for example, the second cylinder And a second combined exhaust passage 31b connected to an exhaust port (not shown) of the third cylinder (# 2, # 3 in FIG. 1), and these first and second combined exhaust passages are formed. 31a and 31b are independently connected to two nozzle passages, which will be described later, of the twin entry type exhaust turbocharger 14. In other words, exhaust interference occurs between the cylinders (for example, the first cylinder and the third cylinder) in which the exhaust stroke order is adjacent and the exhaust valve opening periods partially overlap, so that the exhaust passage is divided into two systems and exhausted. The exhaust gas passages 31a and 31b of the two systems are combined so that the exhaust gas is merged in the same system between the cylinders (for example, the first cylinder and the fourth cylinder) that are separated from each other without overlapping the opening periods of the exhaust valves. Is provided.

  In the air-fuel ratio sensor 33, for example, whether the oxygen concentration in the exhaust gas passing through the downstream exhaust pipe 32 is a value corresponding to the stoichiometric air-fuel ratio (the air-fuel ratio in which gasoline and air are completely burned and no surplus oxygen remains). It consists of an exhaust oxygen concentration sensor whose output changes depending on whether or not.

The exhaust aftertreatment device 34 is composed of, for example, a three-way catalyst, and reduces NOx in the exhaust gas to NO ₂ or NO and reacts with HC or CO in the exhaust gas to form N ₂ or oxidizes HC or CO. H ₂ O or CO ₂ . The engine 10 is feedback-controlled by the ECU 30 based on the detection information of the air-fuel ratio sensor 33, and is operated at a stoichiometric air-fuel ratio that provides good exhaust purification characteristics of the exhaust aftertreatment device 34.

  The intake air compressor 14 </ b> C and the exhaust turbine 14 </ b> T of the exhaust turbocharger 14 are integrally connected to each other in the rotation direction, and the exhaust turbine 14 </ b> T is rotated by exhaust energy in the exhaust device 13 and the intake air compressor in the intake device 12. 14C can be rotated, and supercharging can be performed in which more air is sucked into the engine 10 than natural intake air.

  Further, the exhaust turbocharger 14 introduces exhaust from the first cylinder and the fourth cylinder of the engine 10 into the exhaust turbine 14T, and squeezes and accelerates the first nozzle passage portion 14a, and the exhaust turbine. 14T has a second nozzle passage portion 14b for introducing exhaust from the second cylinder and the third cylinder of the engine 10 and accelerating by narrowing the flow path. The exhaust turbo supercharger 14 is configured to be a high turbine by supplying exhaust gas from the first nozzle passage portion 14a and the second nozzle passage portion 14b to the turbine rotor 14c of the exhaust turbine 14T without pressure drop due to exhaust interference. It can operate at operating efficiency.

  The exhaust gas recirculation device 15 includes an exhaust gas recirculation EGR passage 51 (exhaust gas recirculation passage) that bypasses the combustion chamber in the engine 10 and connects the exhaust passage in the exhaust manifold 31 and the intake passage in the intake manifold 21. The EGR valve 52 (three-way exhaust gas recirculation valve) that adjusts the exhaust gas recirculation amount through the EGR passage 51, the EGR cooler 53 (exhaust cooler) that cools the exhaust gas recirculating through the EGR passage 51, and the EGR cooler 53 EGR cooler pre-catalyst units 54 that purify the exhaust gas are respectively provided.

  Here, the EGR passage 51 is an exhaust gas recirculation passage that recirculates part of the exhaust gas from the exhaust passage side of the engine 10 to the intake passage side, and the EGR cooler 53 uses a part of the exhaust gas recirculation passage as a cooling passage. Further, the EGR valve 52 can be switched between, for example, a valve opening state in which exhaust gas is recirculated to the intake passage side and a valve closing state in which the connection is cut off, and the length of the valve opening instruction signal from the ECU 30 per predetermined time. The opening degree can be controlled by the ratio (duty ratio). Of course, the EGR valve 52 may be of a type that changes the rotation angle of the rotary valve body from the fully open position to the fully closed position.

  The EGR cooler 53 cools the exhaust gas recirculated through the EGR passage 51 by heat exchange with cooling water passing through the cooling system of the engine 10. Further, the EGR cooler pre-catalyst unit 54 is configured by a three-way catalyst similar to the exhaust aftertreatment device 34, for example.

  On the other hand, the EGR passage 51 includes a first passage portion 51a and a second passage portion 51b that extend from the first combined exhaust passage 31a and the second combined exhaust passage 31b of the exhaust manifold 31 to the EGR valve 52 that is a three-way valve. And a third passage portion 51c extending from the EGR valve 52 to the surge tank 27, and a part of the exhaust gas of the engine 10 is supplied to the first passage portion 51a, the second passage portion 51b, and the third passage portion 51c. And can be recirculated to the intake passage side. Here, the first passage portion 51a is connected to the first combined exhaust passage 31a of the exhaust manifold 31, and the second passage portion 51b is connected to the second combined exhaust passage 31b of the exhaust manifold 31, and the third passage. The portion 51 c is connected to the internal space of the surge tank 27 that is a part of the intake passage of the engine 10.

  Further, the EGR cooler 53 is partitioned into a first cooler region 53a and a second cooler region 53b corresponding to the first passage portion 51a and the second passage portion 51b of the EGR passage 51, and the first cooler region 53a is an EGR passage. A part of the first passage portion 51 a of the 51 and the second cooler region 53 b form a part of the second passage portion 51 b of the EGR passage 51, respectively.

  The EGR cooler pre-catalyst unit 54 is partitioned into a first catalyst region 54a and a second catalyst region 54b corresponding to the first passage portion 51a and the second passage portion 51b of the EGR passage 51, and the first catalyst region 54a. Is a part of the first passage 51a upstream of the EGR cooler 53, and the second catalyst region 54b is a part of the second passage 51b upstream of the EGR cooler 53.

  The first cooler region 53a and the second cooler region 53b of the EGR cooler 53 and the first catalyst region 54a and the second catalyst region 54b of the pre-EGR cooler catalyst unit 54 are part of the first passage portion 51a of the EGR passage 51. In some sections of the second passage portion 51b, a large number of narrow exhaust gas passages or a large number of narrow exhaust gas passages that bend or change in cross-sectional area are formed inside (for example, each cooler). The regions 53a and 53b have the same cooling passage structure as the EGR cooler described in JP-A-2006-348873, and the catalyst for purification described in JP-A-2005-240641 is formed in each of the catalyst regions 54a and 54b. It is configured to have a similar passage structure). A number of narrow exhaust gas passages in the first cooler region 53a and the second cooler region 53b of the EGR cooler 53 and the first catalyst region 54a and the second catalyst region 54b of the pre-catalyst EGR cooler unit 54 are provided for each region. Further, pulsation reduction passages 53wa, 53wb, 54wa, 54wb for attenuating the pulsation of the pressure of the exhaust gas passing through the first passage portion 51a and the second passage portion 51b are configured, and the EGR cooler 53 and the EGR cooler pre-catalyst unit 54 are configured. Is a pulsation reducing means that reduces pulsation of exhaust gas passing through the first passage portion 51a and the second passage portion 51b of the EGR passage 51 by forming these pulsation reduction passages 53wa, 53wb, 54wa, 54wb.

  FIG. 3A to FIG. 3D illustrate a plurality of partition forms of the first passage portion 51a and the second passage portion 51b of the EGR passage 51 in the respective pipe cross sections. As shown in the figure, the passage portions 51a and 51b can be partitioned by providing at least one partition plate 51v or inner cylinder 51i, or by providing an additional partition plate 51w. The same applies to the first cooler region 53a and the second cooler region 53b of the EGR cooler 53 and the first catalyst region 54a and the second catalyst region 54b of the EGR cooler pre-catalyst unit 54. Although not shown in detail, the EGR cooler 53 and the exhaust gas recirculation passage inside the EGR cooler pre-catalyst unit 54 are partitioned by a partition plate, 53v, 54v, and the like.

  The first cooler region 53a and the second cooler region 53b of the EGR cooler 53 and the first catalyst region 54a and the second catalyst region 54b of the EGR cooler pre-catalyst unit 54 are independent of each other, not a partitioned region. Although two EGR coolers and two EGR cooler pre-catalyst units may be used, it is preferable to divide only the exhaust gas recirculation passage into two in terms of catalyst warm-up performance and simplification of the structure.

  The EGR valve 52 includes two inlet ports 52a and 52b to which the first passage portion 51a and the second passage portion 51b of the EGR passage 51 are connected, and one outlet port to which the third passage portion 51c of the EGR passage 51 is connected. 52c, and is configured as a three-way solenoid valve interposed between the first passage portion 51a and the second passage portion 51b of the EGR passage 51 and the third passage portion 51c. Further, the EGR valve 52 includes a valve-open state in which the first passage portion 51a, the second passage portion 51b, and the third passage portion 51c are in communication with each other, and the first passage portion 51a, the second passage portion 51b, and the third passage portion 51c. The valve can be switched to a closed state in which communication between the two is cut off.

  Specifically, as shown in FIG. 2, the EGR valve 52 individually blocks the valve opening position [I] that allows the inlet ports 52a and 52b to communicate with the outlet port 52c, and the inlet ports 52a and 52b and the outlet port 52c. A valve body 52v that can be switched to the closed valve position [II], a spring 52p that normally biases the valve body 52v in the valve closing direction, and an electromagnetic operation that can drive the valve body 52v in the valve opening direction. Part 52s. The configuration of such a three-way valve itself is the same as a known one, but the electromagnetic operation unit 52s is excited and driven by a valve opening instruction signal per predetermined time from the ECU 30, and the EGR valve 52 is turned on by a valve opening instruction signal. The opening can be set according to the duty ratio.

  In the exhaust gas recirculation device for the internal combustion engine of the present embodiment configured as described above, the first passage portion 51a which is an exhaust gas recirculation passage from the first combined exhaust passage 31a and the second combined exhaust passage 31b to the EGR valve 52. And in the 2nd channel | path part 51b, the 1st cooler area | region 53a and the 2nd cooler area | region 53b of the EGR cooler 53 which are the one part especially, and the 1st catalyst area | region 54a and the 2nd catalyst area | region 54b of the catalyst unit 54 before EGR cooler In this case, it passes through a large number of thin exhaust gas passages or a large number of thin exhaust gas passages that are further bent or change in cross-sectional area, and the pressure of the exhaust gas passing through the first passage portion 51a and the second passage portion 51b is reduced. The pulsation is effectively attenuated inside the EGR cooler 53 and the EGR cooler pre-catalyst unit 54. Therefore, when the EGR valve 52 is opened, when the two systems of combined exhaust gas passing through the first passage portion 51a and the second passage portion 51b are further merged inside the EGR valve 52 and gathered for all cylinders, exhaust interference occurs. Is effectively suppressed.

  Further, in the present embodiment, when the EGR valve 52 is closed, the first passage portion 51a and the second passage portion 51b are blocked, thereby reliably preventing exhaust interference.

  In addition, in this embodiment, the passage length to the pre-EGR cooler catalyst unit 54 can be shortened, so that the pre-EGR cooler catalyst unit 54 can be easily mounted.

  As described above, in the present embodiment, in the engine 10 including the two combined exhaust passages and the twin entry type exhaust turbocharger 14, the EGR cooler pre-catalyst unit 54 is easily provided in front of (upstream of) the EGR cooler 53. It is possible to provide the exhaust gas recirculation device 15 that can be mounted on the vehicle and that can effectively reduce the exhaust pulsation and suppress the exhaust interference.

  In the present embodiment, the EGR valve 52 is disposed downstream of the EGR cooler 53 (the side away from the first and second combined exhaust passages), but the EGR valve 52 is upstream of the EGR cooler 53. (The first and second combined exhaust passage sides) or further upstream of the EGR cooler pre-catalyst unit 54 may be disposed. However, in that case, at least one of the EGR cooler 53 and the pre-EGR catalyst unit 54 cannot function as a pulsation reducing unit, and thus another pulsation reducing unit as exemplified in the next embodiment is required. .

(Second Embodiment)
4 to 6 show an exhaust gas recirculation device for an internal combustion engine according to a second embodiment of the present invention.

  In addition, since the whole structure including the internal combustion engine of this embodiment is similar to that in 1st Embodiment, about the same or similar component, it respond | corresponds to 1st Embodiment shown in FIGS. 1-3. Only the differences will be described in detail.

  The exhaust gas recirculation device 65 shown in FIG. 4 bypasses the combustion chamber in the engine 10 and communicates the exhaust passage in the exhaust manifold 31 with the intake passage in the intake manifold 21 (exhaust recirculation EGR passage 71). A passage), an EGR valve 72 (three-way exhaust recirculation valve) that adjusts the exhaust gas recirculation amount through the EGR passage 71, an EGR cooler 73 (exhaust cooler) that cools the exhaust gas recirculating through the EGR passage 71, and EGR An EGR pre-cooler pre-catalyst unit 74 that purifies exhaust gas entering the cooler 73 is provided.

  The EGR passage 71 is an exhaust gas recirculation passage that recirculates part of the exhaust gas from the exhaust passage side of the engine 10 to the intake passage side. The EGR passage 71 includes a first passage portion 71a and a second passage portion 71b that extend from the first combined exhaust passage 31a and the second combined exhaust passage 31b of the exhaust manifold 31 to the EGR valve 72 that is a three-way valve; The third passage portion 71c extends from the EGR valve 72 to the surge tank 27, and a part of the exhaust gas of the engine 10 is transferred to the first passage portion 71a, the second passage portion 71b, and the third passage portion 71c. It can be recirculated to the intake passage side through. Here, the first passage portion 71a is connected to the first combined exhaust passage 31a of the exhaust manifold 31, the second passage portion 71b is connected to the second combined exhaust passage 31b of the exhaust manifold 31, and the third passage The portion 71 c is connected to the internal space of the surge tank 27 that is a part of the intake passage of the engine 10.

  In the first passage portion 71a and the second passage portion 71b of the EGR passage 71, mesh-like passage forming members 77 and 78 as shown in FIG. 6 are arranged, respectively. These mesh-like passage forming members 77 and 78 are made of, for example, a mesh-like metal plate, and a part of the first passage part 71a and a part of the second passage part 71b are respectively shown in FIG. 6 (a). It is formed as pulsation reduction passages 77a and 78a which are fine pore passages. Further, as shown in FIG. 6B, the mesh-like passage forming members 77 and 78 are disposed between the flange portions 91 f and 92 f of the two exhaust pipes 91 and 92 that form the first passage portion 71 a of the EGR passage 71. The exhaust pipes 91 and 92 are supported via a cylindrical member 93 having a larger diameter, and the pressure loss is reduced by expanding the diameter of the first passage portion 71a by a predetermined interval before and after the mesh-like passage forming member 77. It is like that.

  The EGR valve 72 can be switched, for example, between a valve opening state in which exhaust gas is recirculated to the intake passage side and a valve closing state in which the connection is cut off. The EGR valve 72 is opened according to the duty ratio of the valve opening instruction signal per predetermined time. It consists of a two-way valve that can control the degree.

  The EGR cooler 73 cools the exhaust gas recirculated through the EGR passage 71 by heat exchange with cooling water passing through the cooling system of the engine 10. The EGR cooler pre-catalyst unit 74 is composed of, for example, an oxidation catalyst or a three-way catalyst. These EGR cooler 73 and EGR cooler pre-catalyst unit 74 are each arranged in the middle of the third passage portion 71c.

  By the way, the EGR valve 72 includes two inlet ports 72a and 72b to which the first passage portion 71a and the second passage portion 71b of the EGR passage 71 are connected and the EGR passage 71 in the same manner as in the first embodiment. A three-way solenoid valve interposed between the first passage portion 71a of the EGR passage 71 and the second passage portion 71b and the third passage portion 71c. It is configured as. In addition, the EGR valve 72 is in a valve-open state in which the first passage portion 71a, the second passage portion 71b, and the third passage portion 71c communicate with each other, and the first passage portion 71a, the second passage portion 71b, and the third passage portion 71c. The valve can be switched to a closed state in which communication between the two is cut off.

  Specifically, as shown in FIG. 5, the EGR valve 72 individually blocks the valve opening position [I] that allows the inlet ports 72a and 72b to communicate with the outlet port 72c, and the inlet ports 72a and 72b and the outlet port 72c. A valve body 72v that can be switched to the closed valve position [II], a spring 72p that normally biases the valve body 72v in the valve closing direction, and an electromagnetic operation that can drive the valve body 72v in the valve opening direction. 72s.

  Instead of the EGR valve 72, it is also conceivable to use a three-position switching valve such as the EGR valve 82 shown in FIG. The EGR valve 82 includes a first valve opening position [I] for communicating the inlet port 82a with the outlet port 82c, a second valve opening position [II] for communicating the inlet port 82b with the outlet port 82c, the inlet port 82a, A valve element 82v that can be switched to a neutral valve closing position [III] that individually blocks the valve 82b and the outlet port 82c, and a pair of springs 82p that constantly bias the valve element 82v to the neutral valve closing position [III]. And a pair of electromagnetic operation portions 82s that can drive the valve body 82v to the first and second valve opening positions.

  However, in this case, since the recirculated exhaust gas passing through the EGR passage 71 becomes exhaust gas for one system only from any one of the first passage portion 71a and the second passage portion 71b of the EGR passage 71, the recirculation amount Because there is a difference in the exhaust gas pressure between the two combined exhaust passages where the exhaust period is insufficient and the exhaust period is separated, another means must be loaded so that the combustion of the engine 10 is not affected. The EGR valve 72 is preferred.

  Also in the present embodiment, in the first passage portion 71a and the second passage portion 71b which are exhaust gas recirculation passages from the first combined exhaust passage 31a and the second combined exhaust passage 31b to the EGR valve 72, in particular, a part thereof Narrow exhaust gas passages having a large number of pressure pulsating exhaust gas in the pulsation reducing passages 77a and 78a of the mesh-like passage forming members 77 and 78 and the enlarged diameter sections of the first passage portion 71a and the second passage portion 71b before and after that. As a result, the first passage portion 71a and the second passage portion 71b are effectively attenuated. Therefore, when the EGR valve 72 is opened, when the two systems of combined exhaust gas passing through the first passage portion 71a and the second passage portion 71b are further joined inside the EGR valve 72 and gathered for all the cylinders, exhaust interference occurs. Is effectively suppressed.

  Also in the present embodiment, when the EGR valve 72 is closed, the first passage portion 71a and the second passage portion 71b are blocked, so that exhaust interference is reliably prevented, and the EGR cooler pre-catalyst unit 74 can be prevented. Since the passage length can be shortened, the EGR cooler pre-catalyst unit 74 can be easily mounted.

  In each of the above-described embodiments, the engine 10 is a gasoline engine. However, a diesel engine may be used, and an arbitrary four-cycle engine using a different fuel may be used. Further, the catalyst unit before the exhaust cooling air is not limited to the oxidation catalyst or the three-way catalyst, but may be a NOx storage catalyst or a diesel particulate filter. Further, when the EGR valve having a three-way valve configuration is arranged downstream of the EGR cooler, each pair of EGR coolers and the EGR cooler pre-catalyst unit may be arranged in parallel. In the case where the EGR cooler pre-catalyst unit is disposed on the downstream side, the pair of EGR cooler pre-catalyst units may be arranged in parallel.

  As described above, the exhaust gas recirculation apparatus for an internal combustion engine according to the present embodiment easily mounts a catalyst unit in front of an exhaust cooler in an internal combustion engine including two merged exhaust passages and a twin entry type exhaust turbocharger. It is possible to provide an exhaust gas recirculation device for an internal combustion engine capable of effectively reducing exhaust pulsation and suppressing exhaust interference, and exhaust from a plurality of cylinders so as to avoid exhaust interference. This is useful for exhaust gas recirculation devices that are installed in internal combustion engines that are divided into two systems and introduced into twin-entry exhaust turbochargers.

10 Engine (Internal combustion engine)
11 cylinder 12 intake device 13 exhaust device 14 exhaust turbocharger 14C intake air compressor 14T exhaust turbine 15 exhaust recirculation device 22 intake pipe (intake passage)
27 Surge tank (intake passage)
30 ECU (Electronic Control Unit)
31 Exhaust manifold 31a First combined exhaust passage 31b Second combined exhaust passage 32 Exhaust pipe (exhaust passage)
51, 71 EGR passage (exhaust gas recirculation passage)
51a, 71a 1st passage part 51b, 71b 2nd passage part 51c, 71c 3rd passage part 51i Inner cylinder 51v, 51w Partition plate 52, 72 EGR valve (three-way exhaust recirculation valve)
52a, 52b, 72a, 72b Inlet port 52c, 72c Outlet port 53, 73 EGR cooler (exhaust cooler)
53a First cooler region 53b Second cooler region 53wa, 53wb, 54wa, 54wb Pulsation reduction path 54, 74 EGR cooler pre-catalyst unit 54a First catalyst region 54b Second catalyst region 77, 78 Reticulated passage forming member 77a, 78a Pulsation Reduction passage

Claims (2)

A first combined exhaust passage and a second combined exhaust for exhausting exhaust gases from a plurality of cylinders adjacent to each other in the exhaust stroke order and merging exhaust gases from a plurality of cylinders that are separated from each other in the exhaust stroke order Exhaust gas recirculation apparatus equipped in an internal combustion engine comprising a passage and a twin entry type exhaust turbocharger having two nozzle passages connected to the first combined exhaust passage and the second combined exhaust passage Because
A first passage portion connected to the first combined exhaust passage, a second passage portion connected to the second combined exhaust passage, and a third passage portion connected to the intake passage of the internal combustion engine; An exhaust gas recirculation passage capable of recirculating a part of the exhaust gas of the internal combustion engine to the intake passage through the first passage portion, the second passage portion, and the third passage portion;
A three-way exhaust recirculation valve interposed between the first passage portion and the second passage portion and the third passage portion of the exhaust recirculation passage;
A pulsation reduction path for attenuating pulsation of exhaust gas pressure passing through the first passage part and the second passage part, respectively, in a part of the first passage part and a part of the second passage part of the exhaust gas recirculation passage An exhaust gas recirculation device for an internal combustion engine, comprising: pulsation reducing means for forming an internal combustion engine. The three-way exhaust recirculation valve is in a valve-open state in which the first passage portion, the second passage portion, and the third passage portion are communicated, and the first passage portion, the second passage portion, and the third passage portion. Is switched to a closed state that cuts off the communication between them,
The pulsation reducing means passes through the first passage portion and the second passage portion on the upstream side of the exhaust cooler, and an exhaust cooler that cools the exhaust gas that passes through the first passage portion and the second passage portion. The exhaust gas recirculation device for an internal combustion engine according to claim 1, characterized by comprising an exhaust gas purification catalyst unit for purifying exhaust gas.

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