JP2009002286A - Exhaust recirculating device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust recirculating device of an internal combustion engine capable of scavenging exhaust gas and new air in an exhaust gas recirculating passage and reducing delay of starting of an EGR caused by the new air residing in the exhaust gas recirculating passage. <P>SOLUTION: This exhaust recirculating device of the internal combustion engine has an EGR passage 54 to recirculate a part of exhaust gas to an air inlet system and an EGR valve 55 to switch in response to a driving state of the engine provided in this EGR passage and to regulate a flow rate of the exhaust gas. A scavenging passage 12 to discharge the new air delivered and supplied to an engine body to the downstream side from an opening part 54a on the side of an exhaust passage 46 of the EGR passage 54 is provided inside the EGR passage 54. It is possible to reduce the delay of the starting of the EGR caused by the new air residing inside the EGR passage 54 and to exert an EGR effect at an early stage as it is possible to scavenge the new air residing inside the EGR passage 54 and to immediately recirculate the EGR gas in the EGR passage 54. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine that scavenges fresh air remaining in an EGR passage and performs EGR at an early stage.

Conventionally, a part of the exhaust gas (EGR gas) discharged from the combustion chamber of the internal combustion engine into the exhaust passage is exhausted and recirculated (hereinafter referred to as “EGR”) to the intake passage of the internal combustion engine and recirculated. The combustion temperature is reduced to suppress the generation of nitrogen oxides (NO _x ).

Generally, in a three-way catalyst for purifying exhaust gas mounted on a vehicle, hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides that are harmful components in exhaust gas discharged from the engine body of the internal combustion engine (NO _x ) is rendered harmless by oxidation-reduction reaction under high temperature conditions. In order to effectively exhibit the purification ability of the exhaust gas, it is necessary to raise the catalyst bed temperature of the three-way catalyst to the activation temperature (for example, 300 to 400 ° C.).

  Until the catalyst temperature rises to the activation temperature after the engine is started, the exhaust gas purification capacity is low, the amount of harmful components in the exhaust gas increases, and the emission deteriorates. For this reason, the exhaust gas recirculation passage is also used as the secondary air passage, and a part of the intake air sucked from the supercharger is supplied to the exhaust passage by flowing back through the exhaust gas recirculation passage. Thus, the catalyst is warmed up to the activation temperature early after the engine is started.

FIG. 8 is a schematic diagram schematically showing the configuration of a conventional exhaust gas recirculation device for an internal combustion engine. As shown in FIG. 8, a conventional exhaust gas recirculation device for an internal combustion engine includes an intake passage 102 and an exhaust passage 103 connected to the engine 101, and an exhaust gas provided by bypassing the intake passage 102 in the middle of the exhaust passage 103. A recirculation passage (hereinafter referred to as “EGR passage”) 104 and an exhaust gas recirculation control valve (hereinafter referred to as “EGR valve”) 105 that is switched according to the operating state of the engine are provided. In the figure, P ₁ indicates the gas pressure in the intake passage, and P ₂ indicates the gas pressure in the exhaust passage. The arrows in the intake passage 102 and the exhaust passage 103 indicate the gas flow direction.

  At the time of supercharging, it is discharged from a supercharger 106 provided in the intake passage 102, and each cylinder (not shown) in the engine 101 is filled with compressed air (hereinafter referred to as “new air”), and the intake air A part of the EGR passage 104 is reversely flowed (rightward in the figure) and supplied to the exhaust passage 103 so that the catalyst is warmed up early after the engine is started. Further, a throttle valve 107 is provided in the intake passage 102 to control the intake air amount (Patent Documents 1, 2, 3, and Non-Patent Document 1).

Japanese Patent Laid-Open No. 08-254158 JP 09-137740 A Yoshiko Shimizu, Yukio Yoshioka, “Catalyst Bed Temperature Control Exhaust System”, Toyota Technical Public Disclosure Toyota Motor Corporation, August 30, 2002, p83-84 Japanese Utility Model Publication No. 62-110512

Here, in the conventional exhaust gas recirculation device for an internal combustion engine, when the EGR valve 105 is closed, the fresh air stays in the EGR passage 104 as shown in FIG. Further, as shown in FIG. 10, during low load operation, when a part of the exhaust gas in the exhaust passage 103 is recirculated into the EGR passage 104 and the EGR valve 105 is opened during EGR, the gas in the exhaust passage 103 is opened. Since the pressure P ₂ is larger than the gas pressure P _{3 of} fresh air staying in the EGR passage 104, the fresh air staying in the EGR passage 104 is discharged to the intake passage 102 side. There is a problem that the exhaust gas flowing into the EGR passage 104 from the exhaust passage 103 cannot be recirculated to the intake passage 102 side until the exhaust gas flows into the intake passage 102.

  Further, even if the EGR valve 105 is opened, the exhaust gas is not immediately flown into the intake passage 102 side, so the EGR is not started immediately. As a result, the EGR is not started immediately and the EGR effect cannot be obtained early. There is.

  Therefore, it is desired to reduce the delay of the start of EGR caused by fresh air staying in the EGR passage 104.

  The present invention has been made in view of the above-described object, and is capable of scavenging the exhaust gas and fresh air in the exhaust gas recirculation passage, and the EGR caused by the fresh air staying in the exhaust gas recirculation passage. An object of the present invention is to provide an exhaust gas recirculation device for an internal combustion engine that reduces a delay in starting.

  An exhaust gas recirculation device for an internal combustion engine according to the present invention connects an intake passage provided in an intake system of an engine body, an exhaust passage provided in the exhaust system, and between the exhaust passage and the intake passage, from the exhaust passage. An exhaust gas recirculation passage for recirculating part of the exhaust gas to the intake passage; and an exhaust gas recirculation control valve provided in the exhaust gas recirculation passage for adjusting a flow rate of the exhaust gas flowing through the exhaust gas recirculation passage. In the exhaust gas recirculation device for an internal combustion engine, the exhaust gas recirculation passage is provided with a scavenging passage for exhausting fresh air for feeding the engine body downstream from the exhaust gas side opening of the exhaust gas recirculation passage. When the engine body is supercharged, fresh air that is supplied into the exhaust gas recirculation passage and stays in the exhaust gas recirculation passage when the exhaust gas recirculation control valve is closed is fed to the exhaust gas recirculation passage. Characterized by scavenging by that the exhaust gas.

  The exhaust gas recirculation device for an internal combustion engine according to the present invention includes at least one cooler for cooling the exhaust gas in one or both of the exhaust gas recirculation passage and the scavenging passage. Features.

  In the exhaust gas recirculation device for an internal combustion engine according to the present invention, the opening for exhausting the exhaust gas in the scavenging passage is provided upstream of the exhaust gas purification device for purifying the exhaust gas in the exhaust passage. It is characterized by that.

  In the exhaust gas recirculation apparatus for an internal combustion engine according to the present invention, a turbine is provided between the opening on the exhaust passage side of the exhaust gas recirculation passage and the opening for discharging the exhaust gas in the scavenging passage. It is characterized by.

  According to the present invention, the exhaust gas recirculation passage is provided with a scavenging passage that discharges the engine main body supply fresh air to the downstream side of the exhaust gas recirculation passage opening on the exhaust gas recirculation passage. Since fresh air that passes through the exhaust gas recirculation passage, closes the exhaust gas recirculation control valve, and stays in the exhaust gas recirculation passage can be discharged from the opening of the scavenging passage, The exhaust gas flowing into the exhaust gas recirculation passage and the scavenging passage can be immediately discharged to the intake passage side of the exhaust gas recirculation passage and can be recirculated. Thereby, the delay of the start of EGR caused by the fresh air staying in the exhaust gas recirculation passage can be reduced, and the EGR effect can be exhibited early.

FIG. 1 is a schematic diagram schematically showing the configuration of an engine system in which an exhaust gas recirculation device for an internal combustion engine according to a first embodiment of the present invention is applied to a vehicle.
As shown in FIG. 1, a diesel engine (DE) 11 is mounted as an internal combustion engine in a vehicle on which the exhaust gas recirculation apparatus according to the first embodiment is mounted. The crankshaft (not shown) of DE11 is provided with a crank position sensor 21 for detecting the piston position and the engine speed. The crank position sensor 21 is connected to the ECU 22 and outputs a detection result. The drive by DE11 is controlled by ECU22, and distribution of the output of DE11 is determined by ECU22 and output.

  In addition, although not shown, a diesel engine (DE) 11 as an internal combustion engine has a cylinder head fastened on a cylinder block, and pistons are fitted to a plurality of cylinder bores so as to be vertically movable. A crankcase is fastened to the lower part of the cylinder block, a crankshaft is rotatably supported in the crankcase, and each piston is connected to the crankshaft via a connecting rod.

  A plurality of combustion chambers 31 are constituted by a cylinder block, a cylinder head, and pistons, and the combustion chamber 31 is formed with an intake port 32 and an exhaust port 33 facing each other at the upper portion. The lower end portions of the intake valve 34 and the exhaust valve 35 are positioned with respect to 33. The intake valve 34 and the exhaust valve 35 are supported by the cylinder head so as to be movable along the axial direction, and are urged and supported in a direction to close the intake port 32 and the exhaust port 33. In addition, an intake cam shaft and an exhaust cam shaft are rotatably supported by the cylinder head, and the intake cam and the exhaust cam are in contact with upper end portions of the intake valve 34 and the exhaust valve 35 through a roller rocker arm.

  Therefore, when the intake camshaft and the exhaust camshaft rotate in synchronization with DE11, the intake cam and the exhaust cam actuate the roller rocker arm, and the intake valve 34 and the exhaust valve 35 move up and down at a predetermined timing. 32 and the exhaust port 33 can be opened and closed to allow the intake port 32 and the combustion chamber 31 to communicate with the combustion chamber 31 and the exhaust port 33, respectively.

  An intake pipe (intake passage) 37 is connected to the intake port 32 via an intake manifold 36, and an air cleaner 38 is attached to an air intake port of the intake pipe 37. A throttle valve 39 is provided on the downstream side of the air cleaner 38. Each cylinder head is provided with an injector 41 capable of injecting light oil as fuel into each combustion chamber 31 at a high pressure. Each injector 41 is connected to a fuel pump 44 via a delivery pipe 42 and a fuel supply pipe 43, and the fuel pump 44 is driven by the DE 11. On the other hand, an exhaust pipe (exhaust passage) 46 is connected to the exhaust port 33 via an exhaust manifold 45.

  The intake pipe 37 and the exhaust pipe 46 are provided with an electric assist turbocharger (MAT) 47. In the electric assist turbocharger 47, a compressor 47a provided in an intake pipe 37 and a turbine 47b provided in an exhaust pipe 46 are integrally connected by a drive shaft 47c, and are forcibly driven by a drive motor 48. can do. An intercooler 49 is provided in the intake pipe 37 on the downstream side of the compressor 47a in the electric assist turbocharger 47 to cool the intake air that has been supercharged by the compressor 47a and whose temperature has risen.

The exhaust pipe 46 is provided with an exhaust purification device 50 that purifies harmful substances contained in the exhaust gas. In the exhaust purification device 50, a first catalyst 51 and a second catalyst 52 are arranged in series. Has been configured. The first catalyst 51 is a storage reduction NO _X catalyst, the occluded NO _X when the air-fuel ratio of exhaust gas occluding NO _X in the exhaust gas when the lean, the oxygen concentration in the exhaust gas was reduced The fuel is released and reduced by the added fuel as a reducing agent (light oil in this embodiment). The second catalyst 52 is a storage reduction NO _X catalyst having a particulate filter, particulates in the exhaust gas (PM: particulates), in particular, as well as collecting the black smoke, when the exhaust air-fuel ratio is lean the NO _X in the exhaust gas is occluded in the one in which the oxygen concentration in the exhaust gas to release NO _X occluding when lowered, is reduced by the added fuel.

  The DE 11 is provided with a high-pressure exhaust gas recirculation (EGR) device 53 that returns exhaust gas to the intake system. The EGR device 53 includes an exhaust gas recirculation passage (EGR passage) 54 that connects the exhaust manifold 45 and the intake pipe 37 immediately before the intake manifold 36 to recirculate a part of the exhaust gas to the intake system, and the EGR passage 54. The exhaust gas recirculation control valve (EGR valve) 55 that is switched according to the operating state of the engine provided in the EGR, and the EGR cooler 56 that is provided in the EGR passage 54 and cools the exhaust gas.

Further, the first catalyst 51 and the second catalyst 52 release the stored NO _x when the oxygen concentration in the exhaust gas is reduced, and reduce the released NO _x with the fuel. A fuel addition valve 57 for injecting fuel (reducing agent) 33 is provided in the cylinder head. The fuel addition valve 57 is connected to the fuel pump 44 through a fuel supply pipe 58, and an open / close valve 59 is provided in the fuel supply pipe 58.

  The ECU 22 can control various devices of the DE 11. That is, the crank angle detected by the crank position sensor 21 is input to the ECU 22, and the ECU 22 determines each stroke of intake, compression, expansion (explosion), and exhaust in each cylinder based on the crank angle. The engine speed is calculated. Further, the ECU 22 receives the accelerator opening detected by the accelerator position sensor 60, and the ECU 22 determines the fuel injection amount based on the accelerator opening and the engine speed. The ECU 22 controls the fuel pump 44 to maintain the fuel pressure in the delivery pipe 42 at a predetermined value, and controls the injector 41 to inject a predetermined amount of fuel into the combustion chamber 31 at a predetermined injection timing. be able to.

In addition, the ECU 22 controls the drive of the electrically assisted turbocharger 47 based on the accelerator opening so that the output of the DE 11 can be adjusted. Furthermore, the ECU 22 controls the drive of the EGR device 53 according to the engine operating state. That is, in a predetermined operating condition, by closing the respective EGR valves 55, the exhaust gas circulates as EGR gas to the intake system through the EGR passage 54, suppressing the occurrence of the NO _X lowers the combustion temperature.

  Further, the ECU 22 regenerates the first catalyst 51 and the second catalyst 52 that constitute the exhaust purification device 50 at a predetermined time. That is, a first temperature sensor 61 that measures the temperature of the exhaust gas is provided on the downstream side of the first catalyst 51, and a second temperature sensor that measures the temperature of the exhaust gas on the downstream side of the second catalyst 52. 62 is provided. Further, a differential pressure sensor 63 is provided for detecting a differential pressure between the pressure of the exhaust gas flowing into the exhaust purification device 50 and the pressure of the exhaust gas discharged from the exhaust purification device 50.

Accordingly, when the DE 11 is operated at a lean air-fuel ratio, the first catalyst 51 and the second catalyst 52 occlude NO _x in the exhaust gas. When the NO _x storage amounts of the first catalyst 51 and the second catalyst 52 reach a predetermined value, the ECU 22 controls the fuel addition valve 57 to inject a predetermined amount of fuel into the exhaust port 33 as a reducing agent. Then, when fuel is supplied to the first catalyst 51 and the second catalyst 52 through the exhaust pipe 46, the oxygen concentration in the exhaust gas is reduced by the oxidation reaction, so that NO _x stored in each of the catalysts 51 and 52 is released. Then, the released NO _x and the fuel react to be reduced and the exhaust gas is purified, whereby the first catalyst 51 and the second catalyst 52 are regenerated.

In this case, the first catalyst 51 and the second catalyst 52 release the stored NO _x , and an active temperature range is set in which the NO _x can be reduced by the fuel. Each catalyst 51, 52 is in this active temperature range. At some point, the ECU 22 performs regeneration control. That is, when the exhaust gas temperature detected by the first temperature sensor 61 is in this activation temperature region, the ECU 22 injects a predetermined amount of fuel by the fuel addition valve 57 and controls the regeneration of the first catalyst 51 and the second catalyst 52. Execute. On the other hand, when the exhaust gas temperature detected by the first temperature sensor 61 is not in the activation temperature region, the ECU 22 performs temperature increase control of the first catalyst 51 and the second catalyst 52. In this temperature increase control, for example, fuel is injected by the fuel addition valve 57 to raise the catalyst temperature, and the exhaust gas temperature is raised by the oxidation reaction in the catalysts 51 and 52 to raise the temperature of the catalysts 51 and 52. The first catalyst 51 and the second catalyst 52 have a deterioration temperature at which the catalyst function deteriorates, and the ECU 22 determines whether the exhaust gas temperature detected by the second temperature sensor 62 does not exceed the deterioration temperature. Monitoring. Further, the NO _X storage amount stored in the first catalyst 51 and the second catalyst 52 is estimated from the continuing engine operating state.

  On the other hand, when the DE 11 is operated at a lean air-fuel ratio, the second catalyst 52 collects PM in the exhaust gas. When the PM collection amount of the second catalyst 52 reaches a predetermined value, the ECU 22 controls the fuel addition valve 57 to inject a predetermined amount of fuel into the exhaust port 33. Then, when fuel is supplied to the first catalyst 51 and the second catalyst 52 through the exhaust pipe 46, the catalyst temperature rises due to the oxidation reaction, so that the PM collected in the second catalyst 52 is burned and regenerated. Is done. In this case, when the pressure difference of the exhaust gas detected by the differential pressure sensor 63 exceeds a predetermined value, the ECU 22 generates a pressure loss in the second catalyst 52 and the amount of PM trapped becomes saturated. It is determined that there is a fuel, a predetermined amount of fuel is injected by the fuel addition valve 57, and regeneration control of the second catalyst 52 is executed.

The fuel contains a sulfur (S) component, and this S component reacts with oxygen to form sulfur oxide (SO _x ). This SO _x is replaced with NO _x by the first catalyst 51 and the first catalyst. 2 is occluded in the catalyst 52. Therefore, when the regeneration control is executed by burning the PM collected by the second catalyst 52, the ECU 22 adjusts the amount of fuel injected by the fuel addition valve 57 and is stored in the first catalyst 51 and the second catalyst 52. Remove SO _X and play.

Therefore, when a predetermined amount of fuel is injected from the fuel addition valve 57 while the electric assist turbocharger 47 is driven to rotate forward when the DE 11 is stopped, the injected fuel flows into the exhaust system and enters the exhaust purification device 50. When it reaches, by repeating the forward drive and the reverse drive of the electric assist turbocharger 47, the fuel reciprocates within the exhaust purification device 50, that is, the first catalyst 51 and the second catalyst 52. . As a result, the fuel is sufficiently diffused in the first catalyst 51 and the second catalyst 52 to be regenerated, and the fuel is sufficiently in contact with each of the catalysts 51 and 52, so that the stored NO _x can be efficiently reduced. In addition, unpurified NO _x and fuel outflow from the catalysts 51 and 52 are suppressed.

Further, the EGR passage 54 is provided with a scavenging passage 12 that discharges fresh air to the downstream side of the opening 54 a on the exhaust passage 46 side of the EGR passage 54. The scavenging passage 12 is supplied into the EGR passage 54 when the engine body is supercharged, and fresh air staying in the EGR passage 54 when the EGR valve 55 is closed is scavenged by the exhaust gas supplied to the EGR passage 54. I am doing so.
Here, the flow of the exhaust gas flowing between the EGR passage 54 and the scavenging passage 12 according to the operating state will be specifically described with reference to FIGS.

2 to 4 are diagrams schematically showing the configuration of the exhaust gas recirculation device for the internal combustion engine in FIG.
FIG. 2 is a diagram simply illustrating the configuration of the exhaust gas recirculation device for the internal combustion engine during supercharging, and FIG. 3 is a diagram schematically illustrating the configuration of the exhaust gas recirculation device for the internal combustion engine when the EGR valve is closed, FIG. 4 is a diagram schematically showing the configuration of the exhaust gas recirculation device for the internal combustion engine during low load operation.
As shown in FIG. 2, at the time of supercharging, fresh air discharged from a supercharger 47 provided in the intake passage 37 is filled in each cylinder (not shown) in the engine 11, and the EGR valve 55 is opened. A part of the fresh air is supplied from the intake passage 37 to the EGR passage 54 and the scavenging passage 12 in the reverse direction (rightward in the figure) and supplied to the exhaust passage 103.

This is because the gas pressure P ₂ in the exhaust passage 46 is lower than the gas pressure P ₁ in the intake passage 37, so that when the EGR valve 55 is opened during supercharging, fresh air in the intake passage 37 becomes EGR passage 54 and scavenged air. This is because it is introduced to the passage 12 side. Specifically, at the time of supercharging, fresh air flows from the opening 54 b on the intake passage 37 side of the EGR passage 54, and a part of the fresh air flows into the scavenging passage 12 at the branch point 13. Then, the exhaust gas flows out from the openings 12a and 54a to the exhaust passage 46 through the EGR passage 54 and the scavenging passage 12, respectively.

  Therefore, by supplying fresh air into the engine 11 and opening the EGR valve 55, a part of the fresh air is supplied from the intake passage 37 to the exhaust passage 46 through the EGR passage 54 and the scavenging passage 12. After the engine is started, the purification catalyst provided in the exhaust gas purification device (not shown) that purifies the exhaust gas in the exhaust passage 46 is warmed up early.

  As shown in FIG. 3, when the EGR valve 55 is closed, EGR gas, which is part of the exhaust gas, flows into the EGR passage 54 from the opening 54a, and fresh air staying in the EGR passage 54 is removed from the scavenging passage. Then, the gas is discharged from the opening 12a through 12 and scavenged. Specifically, when the EGR valve 55 is closed, the inflow of fresh air from the opening 54b of the intake passage 37 is blocked.

The gas pressure P _2-1 of the opening 54a near the exhaust passage 46 side of the EGR passage 54 is higher than the gas pressure P _2-2 of the opening 12a near the exhaust passage 46, EGR gas is EGR passage 54 flows into the EGR passage 54 from the opening 54a on the exhaust passage 46 side. Then, fresh air staying in both the EGR passage 54 and the scavenging passage 12 is discharged from the opening 12a of the scavenging passage 12 by the inflowed EGR gas and is scavenged.

As shown in FIG. 4, when the engine body is in a low load operation, the EGR valve 55 is opened, EGR gas is caused to flow into the EGR passage 54 and the scavenging passage 12, and the opening 54 b on the intake passage 37 side of the EGR passage 54. And then reflux. Since the gas pressure P ₂ in the exhaust passage 46 is higher than the gas pressure P ₁ in the intake passage 37, the exhaust gas in the exhaust passage 46 is introduced to the intake passage 37 side when the EGR valve 55 is opened during low load operation. The Specifically, when the EGR valve 55 is opened, both EGR gas flows from the opening 54 a on the exhaust passage 46 side of the EGR passage 54 and the opening 12 a of the scavenging passage 12. Then, the EGR gas flowing in from the scavenging passage 12 joins with the EGR gas flowing in from the EGR passage 54 at the branching point 13 where the scavenging passage 12 is connected to the EGR passage 54, and from the opening 54 b on the intake passage 37 side of the EGR passage 54. It flows into the intake passage 37. At this time, as described above, since fresh air does not stay in the EGR passage 54 and the scavenging passage 12, the EGR gas that has flowed into the EGR passage 54 and the scavenging passage 12 is opened on the intake passage 37 side of the EGR passage 54. 54b can flow out into the intake passage 37 at an early stage and be recirculated.

  As described above, in the exhaust gas recirculation apparatus for the internal combustion engine according to the present embodiment, the fresh air supplied to the engine body in the EGR passage 54 is downstream of the opening 54a on the exhaust passage 46 side of the EGR passage 54. Since the scavenging passage 12 for discharging is provided, the EGR passage 54 and the scavenging passage 12 are passed during supercharging, the EGR valve 55 is closed, and the fresh air staying in the EGR passage 54 is opened in the scavenging passage 12. 12a, the EGR gas flowing into the EGR passage 54 and the scavenging passage 12 can be immediately discharged to the intake passage 37 side of the EGR passage 54 and recirculated during low load operation of the engine body. Thereby, the delay of the start of EGR resulting from the fresh air staying in the EGR passage 54 can be reduced, and the EGR effect can be exhibited early.

An example in which the exhaust gas recirculation apparatus for an internal combustion engine according to the second embodiment of the present invention is applied to a diesel engine system will be described with reference to FIG.
The exhaust gas recirculation device for the internal combustion engine according to the present embodiment is the same as the configuration of the diesel engine system to which the exhaust gas recirculation device for the internal combustion engine according to the first embodiment is applied. Reference numerals are assigned and description is omitted.
Moreover, the figure which shows the structure of the diesel engine system which applied the exhaust gas recirculation apparatus of the internal combustion engine of Example 1 shown in FIG. 1 is abbreviate | omitted, and demonstrates using the figure which shows the structure of the exhaust gas recirculation apparatus of an internal combustion engine simply.
FIG. 5 is a diagram schematically showing the configuration of the exhaust gas recirculation device for the internal combustion engine according to the embodiment of the present invention.
As shown in FIG. 5, the exhaust gas recirculation apparatus for an internal combustion engine according to the embodiment of the present invention includes one cooler 14 </ b> A that cools the exhaust gas in the passage in both the EGR passage 54 and the scavenging passage 12. The cooler 14 </ b> A is provided on the exhaust pipe side with respect to the branch point 13 between the EGR passage 54 and the scavenging passage 12.

  When the passage area on the intake passage 37 side of the EGR passage 54 is larger than the passage area on the exhaust passage 46 side, scavenging is not sufficiently performed. Therefore, by providing the cooler 14A closer to the exhaust pipe 46 than the branch point 13 between the EGR passage 54 and the scavenging passage 12, the volume to be scavenged can be increased. As a result, the EGR gas can be efficiently cooled while maintaining the scavenging efficiency in the EGR passage 54.

An example in which the exhaust gas recirculation apparatus for an internal combustion engine according to the third embodiment of the present invention is applied to a diesel engine system will be described with reference to FIG.
Since the exhaust gas recirculation apparatus for an internal combustion engine according to the present embodiment is the same as the configuration of the diesel engine system to which the exhaust gas recirculation apparatus for the internal combustion engine according to the first embodiment is applied, as in the description in the second embodiment. 1 are denoted by the same reference numerals, and description thereof is omitted.
Moreover, the figure which shows the structure of the diesel engine system which applied the exhaust gas recirculation apparatus of the internal combustion engine of Example 1 shown in FIG. 1 is abbreviate | omitted, and demonstrates using the figure which shows the structure of the exhaust gas recirculation apparatus of an internal combustion engine simply.
FIG. 6 is a diagram schematically illustrating the configuration of the exhaust gas recirculation device for the internal combustion engine according to the embodiment of the present invention.
As shown in FIG. 6, the exhaust gas recirculation apparatus for an internal combustion engine according to the embodiment of the present invention has an exhaust gas purification apparatus in which an opening 12 a that exhausts exhaust gas in the scavenging passage 12 purifies the exhaust gas in the exhaust passage 46. 50 upstream.

  If either the opening 54a of the EGR passage 54 on the exhaust passage 46 side or the opening 12a of the EGR passage 54 is provided on the downstream side of the exhaust gas purification device 50, the exhaust gas is discharged without passing through the catalyst during operation. Therefore, the gas purification properties of the exhaust gas exhausted during warm-up (during cold) will deteriorate.

  Therefore, by providing the opening 54a of the EGR passage 54 and the opening 12a of the scavenging passage 12 on the upstream side of the exhaust gas purification device 50, the exhaust gas discharged from the engine 11, the EGR passage 54, and the EGR passage 54 are discharged. Since the EGR gas can be passed through the exhaust gas purification device 50, the gas purification performance of the exhaust gas can be maintained.

An example in which the exhaust gas recirculation apparatus for an internal combustion engine according to the fourth embodiment of the present invention is applied to a diesel engine system will be described with reference to FIG.
Since the exhaust gas recirculation device for an internal combustion engine according to the present embodiment is similar to the configuration of the diesel engine system to which the exhaust gas recirculation device for the internal combustion engine according to the first embodiment is applied, as in the description in the second and third embodiments, The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
Moreover, the figure which shows the structure of the diesel engine system which applied the exhaust gas recirculation apparatus of the internal combustion engine of Example 1 shown in FIG. 1 is abbreviate | omitted, and demonstrates using the figure which shows the structure of the exhaust gas recirculation apparatus of an internal combustion engine simply.
FIG. 7 is a diagram schematically showing the configuration of the exhaust gas recirculation device for the internal combustion engine according to the embodiment of the present invention.
As shown in FIG. 7, the exhaust gas recirculation apparatus for an internal combustion engine according to an embodiment of the present invention is provided between the opening 54 a on the exhaust passage 46 side of the EGR passage 54 and the opening 12 a on the exhaust passage 46 side of the scavenging passage 12. In addition, a turbine 47b is provided.

When the differential pressure between the gas pressure P _2-2 near the opening of the exhaust passage 46 side of the opening 54a near the gas pressure P _2-1 and the scavenging passage of the EGR passage 54 is small, the scavenging property is deteriorated. Therefore, an opening 54a on the exhaust passage 46 side of the EGR passage 54 and an opening 12a on the exhaust passage 46 side of the scavenging passage 12 are provided across the turbine 47b. Specifically, the opening 54a on the exhaust passage 46 side of the EGR passage 54 is provided on the upstream side of the turbine 47b, and the opening 12a on the exhaust passage 46 side of the scavenging passage 12 is provided on the downstream side of the turbine 47b. .

As a result, the differential pressure between the gas pressure P _2-1 near the opening 54a on the exhaust passage 46 side of the EGR passage 54 and the gas pressure P _2-2 near the opening of the scavenging passage can be increased. The flow rate can be increased. As a result, the scavenging performance of the EGR passage 54 can be improved.

  In this embodiment, the cooler 14B is provided on the exhaust pipe side of the branch point 13 between the EGR passage 54 and the scavenging passage 12. By providing the cooler 14B closer to the exhaust pipe 46 than the branch point 13 between the EGR passage 54 and the scavenging passage 12, the volume to be scavenged can be increased. As a result, the EGR gas can be efficiently cooled while maintaining the scavenging performance in the EGR passage 54.

  Therefore, the opening 54a on the exhaust passage 46 side of the EGR passage 54 is provided on the upstream side of the turbine 47b across the turbine 47b, and the opening 12a on the exhaust passage 46 side of the scavenging passage 12 is provided on the downstream side of the turbine 47b. Thus, the flow rate of EGR can be increased. As a result, the gas purification performance of the exhaust gas in the EGR passage 54 can be maintained.

  As described above, the exhaust gas recirculation device for an internal combustion engine according to the present invention can scavenge fresh air staying in the EGR passage, so that exhaust gas supplied to the EGR passage is immediately recirculated to the intake passage side. It is useful for reducing the delay in the start of EGR caused by fresh air staying in the EGR passage and exhibiting the EGR effect at an early stage, and is suitable for use in an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view schematically showing a configuration of an engine system in which an exhaust gas recirculation device for an internal combustion engine according to a first embodiment of the present invention is applied to a vehicle. It is a figure which shows simply the structure of the exhaust gas recirculation apparatus of the internal combustion engine at the time of supercharging. It is a figure which shows simply the structure of the exhaust gas recirculation apparatus of the internal combustion engine at the time of closing of an EGR valve. It is a figure which shows simply the structure of the exhaust gas recirculation apparatus of the internal combustion engine at the time of low load operation. It is a figure which shows simply the structure of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on Example 2 of this invention. It is a figure which shows simply the structure of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on Example 3 of this invention. It is a figure which shows simply the structure of the exhaust gas recirculation apparatus of the internal combustion engine which concerns on Example 4 of this invention. It is the schematic which shows simply the structure of the exhaust-gas recirculation apparatus of the conventional internal combustion engine at the time of supercharging. It is the schematic which shows simply the structure of the exhaust-gas recirculation apparatus of the conventional internal combustion engine at the time of closing of an EGR valve. It is the schematic which shows simply the structure of the exhaust-gas recirculation apparatus of the conventional internal combustion engine at the time of low load driving | operation.

Explanation of symbols

11 Diesel engine, DE (internal combustion engine)
12 Scavenging passage 12a Scavenging passage opening 13 Branch point 14A, 14B Cooler 22 ECU
37 Intake pipe (intake passage)
39 Throttle valve 46 Exhaust pipe (exhaust passage)
47 electrically assisted turbocharger 50 exhaust purification device 51 first catalyst (storage reduction NO _X catalyst)
52 second catalyst (storage reduction NO _X catalysts)
54 Exhaust gas recirculation passage (EGR passage)
54a Opening portion on the exhaust passage side of the EGR passage 54b Opening portion on the intake passage side of the EGR passage 55 EGR valve 56 EGR cooler 57 Fuel addition valve P ₁ Gas pressure in the intake passage P ₂ Gas pressure in the exhaust passage P _2-1 Gas pressure near the opening on the exhaust passage side of the EGR passage P _2-2 Gas pressure near the opening on the scavenging passage

Claims (4)

An intake passage provided in the intake system of the engine body and an exhaust passage provided in the exhaust system;
An exhaust gas recirculation passage that connects between the exhaust passage and the intake passage, and recirculates part of the exhaust gas from the exhaust passage to the intake passage;
An exhaust gas recirculation device for an internal combustion engine, provided in the exhaust gas recirculation passage, and having an exhaust gas recirculation control valve for adjusting a flow rate of the exhaust gas flowing through the exhaust gas recirculation passage;
The exhaust gas recirculation passage is provided therein with a scavenging passage for discharging fresh air for engine main body supply to the downstream side of the exhaust gas recirculation passage on the exhaust passage side,
When the engine body is supercharged, fresh air that is supplied into the exhaust gas recirculation passage and stays in the exhaust gas recirculation passage is sent to the exhaust gas recirculation passage when the exhaust gas recirculation control valve is closed. An exhaust gas recirculation device for an internal combustion engine, wherein the exhaust gas is scavenged. In claim 1,
An exhaust gas recirculation device for an internal combustion engine, comprising at least one cooler for cooling the exhaust gas in one or both of the exhaust gas recirculation passage and the scavenging passage. In claim 1 or 2,
An exhaust gas recirculation device for an internal combustion engine, wherein an opening for exhausting the exhaust gas in the scavenging passage is provided upstream of an exhaust gas purification device for purifying the exhaust gas in the exhaust passage. In any one of Claims 1 thru | or 3,
An exhaust gas recirculation device for an internal combustion engine, wherein a turbine is provided between the opening portion of the exhaust gas recirculation passage on the exhaust passage side and the opening portion for discharging the exhaust gas of the scavenging passage. .

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