JP2019100290A - Internal combustion engine - Google Patents

Abstract

To collect condensate water on a downstream side of an EGR cooler, and also suppress corrosion of in-cylinder components due to generation of condensate water on the downstream side.SOLUTION: An EGR device included in an internal combustion engine comprises an EGR cooler installed in an EGR passage, and a storage part. The storage part is installed on a downstream side with respect to the EGR cooler of the EGR passage, and stores condensate water contained in EGR gas. An inlet for EGR gas of the storage part is provided at a position on a lower side with respect to a lower limit water level for condensate water in the storage part, and an outlet is provided at a position on an upper side with respect to an upper limit water level. The EGR device is configured such that EGR gas flowing into the EGR cooler passes through the EGR cooler, then passes through the condensate water stored in the storage part, and flows out to the outside of the storage part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an internal combustion engine provided with an EGR (Exhaust Gas Recirculation) device.

  In the internal combustion engine in which the EGR system is adopted, the water in the EGR gas may be condensed to generate acidic condensed water in the EGR passage and the intake passage. If the generated acidic condensed water flows into the cylinder, it may corrode each member in the cylinder. In order to suppress the inflow of condensed water into the cylinder, for example, Patent Document 1 describes an internal combustion engine provided with a collector that collects condensed water upstream or downstream of an EGR cooler. Specifically, a direction changing portion is provided in the EGR passage upstream or downstream of the EGR cooler of the internal combustion engine of Patent Document 1, and a collector for collecting condensed water is provided on the outer corner of the direction changing portion. , And is installed so as to open toward the upstream side of the EGR gas.

Japanese Patent Application Publication No. 2003-097361

  According to the system of Patent Document 1, the condensed water generated on the upstream side of the collector of the EGR passage can be collected to some extent. However, condensed water may also be generated, for example, by the EGR gas being cooled by low temperature fresh air. As described above, when the condensed water is generated in the intake passage downstream of the collector, etc., the condensed water can not be collected, and the condensed water may flow into the cylinder. In this point, there is room for improvement in collecting condensed water by a collector installed in the EGR passage as in Patent Document 1.

  The present invention has been made in view of the above problems, and while collecting condensed water more reliably, it is effective to cause corrosion of in-cylinder components due to generation of condensed water on the downstream side from the portion where condensed water is collected. It is an object of the present invention to provide an internal combustion engine which is improved to be suppressed.

  The internal combustion engine of the present invention is provided with an EGR device for introducing a part of the exhaust gas from the exhaust passage of the internal combustion engine as an EGR gas into the intake passage. The EGR device includes an EGR passage, an EGR cooler, and a reservoir. The EGR passage is connected to the exhaust passage and the intake passage of the internal combustion engine. The EGR cooler is installed in the middle of the EGR passage to cool the passing EGR gas. The storage portion is installed downstream of the EGR cooler in the EGR passage, and stores condensed water contained in the EGR gas. Here, the downstream side means the downstream side of the flow of the EGR gas flowing from the exhaust passage side to the intake passage side in the EGR passage.

  The inlet of the EGR gas in the storage section is provided at a position lower than the lower limit water level of the condensed water in the storage section. Further, the outlet of the EGR gas in the storage section is provided at a position above the upper limit water level of the condensed water in the storage section. Here, the lower limit water level and the upper limit water level of the condensed water are preset. Further, the vertical direction means the vertical direction in the state where the internal combustion engine is mounted. The EGR device is configured such that the EGR gas flowing into the EGR cooler passes through the EGR cooler, then passes through the condensed water stored in the storage portion, and flows out of the storage portion.

  According to the present invention, the storage portion for storing the condensed water generated by the EGR cooler is provided on the downstream side of the EGR cooler. Therefore, the EGR gas can be dehumidified without suppressing the generation of the condensed water in the EGR cooler, and the generation of the condensed water on the intake passage side can be effectively suppressed. Further, the EGR gas cooled by the EGR cooler passes through the condensed water stored in the storage section. Thereby, the condensed water in EGR gas can be collected more reliably. In addition, the acid component contained in the EGR gas is absorbed into the condensed water. Therefore, even when condensed water is generated from the EGR gas on the downstream side of the EGR passage, the acid concentration of the condensed water is low, and the corrosion of the in-cylinder parts due to the generated condensed water can be suppressed. .

FIG. 1 is a view schematically showing a configuration of an internal combustion engine according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the structure of the EGR cooler of the internal combustion engine which concerns on embodiment of this invention, the catch tank of condensed water, and its vicinity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

  FIG. 1 is a view schematically showing a configuration of an internal combustion engine according to the embodiment. In FIG. 1, the elements constituting the internal combustion engine 1 are drawn and projected onto a plane perpendicular to the crankshaft. An internal combustion engine 1 according to the present embodiment is a multi-cylinder engine (hereinafter simply referred to as an engine) having a plurality of cylinders 2. The number and arrangement of the cylinders 2 are not limited. In the cylinder 2 of the engine 1 is disposed a piston 3 that reciprocates in the axial direction. An intake port 5 and an exhaust port 6 are in communication with a combustion chamber 4 which is an upper space of the cylinder 2. An intake valve 7 is provided at an opening communicating with the combustion chamber 4 of the intake port 5, and an exhaust valve 8 is provided at an opening communicating with the combustion chamber 4 of the exhaust port 6.

  The engine 1 is provided with a supercharger 10. The turbocharger 10 has a turbine 12 operated by exhaust energy of exhaust gas, and a compressor 14 integrally connected to the turbine 12 and rotationally driven by exhaust energy of exhaust gas input to the turbine 12 There is.

  An intake passage 20 is connected to the intake port 5 of each cylinder 2 via an intake manifold. An air cleaner 21 is provided near the inlet of the intake passage 20 of the engine 1. The air drawn through the air cleaner 21 is compressed by the compressor 14 of the turbocharger 10 and then cooled by the intercooler 22. The intake air that has passed through the intercooler 22 passes through the intake throttle valve 23 (i.e., a diesel throttle) and is distributed by the intake manifold to the intake port (not shown) of each cylinder.

  The exhaust passage 24 is branched by an exhaust manifold and connected to the exhaust port 6 of each cylinder. The turbine 12 of the turbocharger 10 is disposed in the middle of the exhaust passage 24. The exhaust passage 24 downstream of the turbine 12 is provided with a catalyst 25 for purifying exhaust gas.

  The engine 1 is equipped with an EGR (Exhaust Gas Recirculation) device. Near the intake manifold in the intake passage 20, one end of an EGR passage 30 of the EGR device is connected. The other end of the EGR passage 30 is connected in the vicinity of the exhaust manifold of the exhaust passage 24. A portion of exhaust gas (burned gas) can be recirculated to the intake passage 20 through the EGR passage 30, that is, external EGR can be performed.

  The EGR passage 30 is branched into an EGR passage 31 and a bypass passage 32 along the way. The EGR passage 31 is provided with an EGR cooler 34 for cooling the EGR gas, and a catch tank 35 which functions as a storage unit for storing condensed water. The bypass passage 32 is a passage parallel to the EGR passage 31, bypasses the EGR cooler 34, and joins the EGR passage 36 together with the EGR passage 31 on the downstream side. A bypass valve 37 is installed at the junction of the bypass passage 32 and the EGR passage 31. Further, an EGR valve 38 for adjusting the amount of EGR gas is installed in the EGR passage 36 after the merging.

  FIG. 2 is a view schematically showing the configuration of the EGR cooler 34 and the catch tank 35 of the present embodiment and the vicinity thereof. In FIG. 2, the bypass passage 32 is omitted and not shown. The EGR cooler 34 is a portion having a function of cooling the EGR gas as well as a well-known EGR cooler. An EGR passage 31 is in communication with an inlet of a passage of the EGR gas in the EGR cooler 34. The outlet of the passage for EGR gas in the EGR cooler 34 is provided on the bottom surface side of the EGR cooler 34, and the passage 40 communicates with the outlet. A lower portion of the EGR gas passage in the EGR cooler 34 is configured to be able to store condensed water, and the condensed water is also stored in the passage 40 connected to the catch tank 35.

  The passage 40 is connected to the EGR gas inlet provided near the bottom of the catch tank 35. The outlet of the EGR gas of the catch tank 35 is provided at the vertically upper portion of the side surface of the catch tank 35, and the EGR passage 31 is in communication with the outlet. More specifically, during the operation of the engine 1, condensed water or water at least equal to or more than a preset lower limit water level and not more than the upper limit water level is stored in the catch tank 35. Then, the inlet of the EGR gas is provided at a portion lower in the vertical direction than the lower limit water level of the side surface of the catch tank 35. However, the inlet may be provided on the bottom of the catch tank 35. In this case, the lower limit water level may be zero. Further, the outlet of the EGR gas is provided at a portion above the upper limit water level in the side surface of the catch tank 35 in the vertical direction. However, the outlet may be provided on the ceiling surface of the catch tank 35.

  Near the upper limit water level of the side surface of the catch tank 35, a discharge port for discharging the condensed water is provided, and a discharge passage 41 communicates with the discharge port. The exhaust passage 41 is connected to the exhaust passage 24 at a portion upstream of the catalyst 25. When the condensed water stored in the catch tank 35 reaches the upper limit water level, ie, the discharge port, the condensed water is discharged from the discharge passage 41 to the outside of the catch tank 35, and the catalyst 25 from the discharge passage 41 via the exhaust passage 24. After being introduced into the country, it is discharged to the outside. Thereby, the amount of condensed water in the catch tank 35 and the EGR cooler 34 is maintained at the upper limit water level.

  As shown in FIG. 2, the condensed water contained in the EGR gas is collected when passing through the EGR cooler 34 and the catch tank 35, and in the EGR gas passage and passage 40 of the EGR cooler 34 and in the catch tank 35. It is stored.

  The EGR gas introduced into the EGR cooler 34 passes through the condensed water stored in the EGR gas passage of the EGR cooler 34 and the passage 40 and is further introduced into the condensed water stored in the catch tank 35 Be done. The EGR gas having passed through the condensed water in the catch tank 35 flows out to the EGR passage 31 from the outlet provided above the catch tank 35 and flows to the intake side.

  As the EGR gas passes through the condensed water, the condensed water in the EGR gas generated in the EGR cooler 34 and the like is separated from the EGR gas and stagnates in the condensed water in the EGR cooler 34 and the catch tank 35. Further, the EGR gas is bubbled into the condensed water, whereby the acid component (i.e., SOx, NOx, organic acid, etc.) contained in the EGR gas is dissolved in the condensed water. As a result, the content of the acid component of the EGR gas leaving the catch tank 35 is reduced. Therefore, even when condensed water is generated from the EGR gas when mixed with fresh air on the intake passage side, the acid concentration of the condensed water is low, and the risk of corrosion of in-cylinder components due to the condensed water can be reduced. .

  Further, a catch tank 35 for collecting condensed water is connected to the downstream side of the EGR cooler 34. Therefore, since the generation of condensed water in the EGR cooler 34 is not suppressed, the EGR gas can be dehumidified effectively, and the generation of condensed water from the EGR gas on the intake side can be more effectively suppressed. Furthermore, since the generation of condensed water in the EGR cooler 34 is not suppressed, it is possible to increase the amount of EGR and expand the EGR execution region, and to further reduce the NOx concentration in the exhaust gas.

  In addition, when the number of the number, the quantity, the quantity, the range, etc. of each element is mentioned in the above embodiment, the case is mentioned except in the case where it is particularly clearly indicated or the case where the number is clearly specified in principle. The invention is not limited to a number. Further, the structures and the like described in this embodiment are not necessarily essential to the present invention, unless otherwise specified or clearly specified in principle.

Reference Signs List 1 engine 2 cylinder 3 piston 4 combustion chamber 5 intake port 6 exhaust port 7 intake valve 8 exhaust valve 10 supercharger 12 turbine 14 compressor 20 intake passage 21 air cleaner 22 intercooler 23 intake throttle valve 24 exhaust passage 25 catalyst 30 EGR passage 31 EGR passage 32 bypass passage 34 EGR cooler 35 catch tank (storage section)
36 EGR passage 37 bypass valve 38 EGR valve 40 passage 41 discharge passage

Claims (1)

An internal combustion engine comprising an EGR device for introducing a part of exhaust gas as EGR gas into an intake passage from an exhaust passage of the internal combustion engine,
The EGR device
An EGR passage connected to an exhaust passage and an intake passage of the internal combustion engine;
An EGR cooler installed in the middle of the EGR passage for cooling the passing EGR gas;
A storage unit disposed downstream of the EGR cooler in the EGR passage and configured to store condensed water contained in the EGR gas;
Equipped with
The inlet of the EGR gas in the storage section is provided at a position lower than a lower limit water level of the condensed water preset in the storage section,
The outlet of the EGR gas in the reservoir is provided at a position above the upper limit water level of the condensed water preset in the reservoir.
The internal combustion engine is characterized in that the EGR gas passes through the condensed water stored in the storage section after passing through the EGR cooler, and flows out of the storage section. .

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