JP2014009682A - Egr device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR device of an internal combustion engine, capable of preventing the deterioration of fuel consumption while suppressing an increase in costs.SOLUTION: A swirl flow generator (35) for making an exhaust gas flow a swirl flow is located in an exhaust pipe (32) downstream of a diesel particulate filter (34). An expansion chamber (36) is formed on the exhaust pipe (32) downstream of the swirl flow generator (35). One end (38a) of a low pressure EGR passage (38) is connected to the outer periphery of the expansion chamber (36) such that the low pressure EGR passage (38) extends toward a side ahead of an exhaust gas swirl direction. An inner wall surface (36a) of the expansion chamber (36) projects inside the expansion chamber (36) such that the inside of a connection (36b) to which the one end (38a) of the low pressure EGR passage (38) is connected stretches to an opposite side of the low pressure EGR passage, and is formed such that an amount of projection to the inside of the expansion chamber (36) is decreased with the distance toward the exhaust gas swirl direction.

Description

  The present invention relates to an EGR device for an internal combustion engine, and more particularly to the structure of an EGR gas extraction portion.

  In an automobile engine, an exhaust gas recirculation (EGR) device that recirculates exhaust gas to intake air is provided in order to reduce nitrogen oxides (NOx) and smoke (soot) in exhaust gas discharged from an internal combustion engine. In recent years, it has been required to introduce a large amount of exhaust gas (EGR gas) into the intake air in response to a significant reduction in NOx, and the downstream of the exhaust catalyst in the exhaust passage and the upstream of the supercharger in the intake passage. A low-pressure EGR device is provided that is connected to the EGR passage through the EGR cooler and introduces low-pressure EGR gas into the intake air upstream of the compressor of the supercharger.

  In such a low-pressure EGR device that introduces low-pressure EGR gas into the intake air upstream of the compressor of the supercharger, an exhaust throttle valve is provided downstream of the connection portion of the EGR passage of the exhaust passage as in Patent Document 1. For example, when the introduction amount of the low pressure EGR gas is increased, the EGR valve provided in the EGR passage is opened, the exhaust throttle valve is closed, the internal pressure of the exhaust pipe upstream of the exhaust throttle valve is increased, and the EGR path of the low pressure EGR device A differential pressure is generated between the intake passage and the intake passage so that the amount of low-pressure EGR gas introduced into the intake passage is increased.

JP 2011-26964 A

As described above, in the low pressure EGR device of Patent Document 1, the exhaust throttle valve is closed, the internal pressure of the exhaust pipe upstream of the exhaust throttle valve is increased, and a differential pressure is generated between the EGR path and the intake passage of the low pressure EGR device. Thus, the amount of low-pressure EGR gas introduced into the intake passage is increased.
However, when the exhaust throttle valve is closed and the internal pressure of the exhaust passage is increased in this way, the pump work of the internal combustion engine increases and fuel consumption deteriorates, which is not preferable.

Also, providing an exhaust throttle valve in the exhaust passage leads to an increase in cost and is not preferable.
The present invention has been made to solve such a problem, and an object of the present invention is to provide an EGR device for an internal combustion engine that can prevent deterioration in fuel consumption while suppressing an increase in cost. There is.

  In order to achieve the above object, in the EGR device for an internal combustion engine according to claim 1, exhaust purification means for purifying exhaust gas discharged from the internal combustion engine is disposed, and after the passage area is expanded downstream of the exhaust purification means. An exhaust passage in which an expansion chamber that is contracted again is formed, an intake passage that introduces air into the internal combustion engine, one end is connected to the outer peripheral portion of the expansion chamber of the exhaust passage so as to communicate with the exhaust passage, An exhaust gas recirculation passage connected to the intake air passage so that an end thereof communicates with the intake air passage, adjusting an introduction amount of the exhaust gas into the intake air passage, and recirculating the exhaust gas to the intake air passage; Circulating means and upstream of the connection portion at the other end of the exhaust gas introduction path of the intake passage, adjust the pressure in the intake passage at the connection portion at the other end of the exhaust gas introduction path, and introduce the exhaust gas Intake pressure to adjust the amount Characterized in that it comprises a settling unit.

In the EGR device for an internal combustion engine according to claim 2, the swirl flow generating means for generating a swirl flow in the exhaust gas is disposed in the exhaust passage between the exhaust purification means and the expansion chamber. It is characterized by providing.
Further, in the EGR device for an internal combustion engine according to claim 3, the exhaust gas swirling direction of the swirling flow of the exhaust gas from the outer peripheral portion of the expansion chamber is the exhaust gas introducing path of the one end of the exhaust gas introducing path. It is connected to the outer peripheral portion of the expansion chamber so as to extend toward the front side of the expansion chamber.

  In the EGR device for an internal combustion engine according to claim 4, the inner wall surface of the expansion chamber according to claim 3 is such that the inside of the connection portion to which the one end of the exhaust gas introduction path is connected protrudes to the inside of the expansion chamber. As the exhaust gas turns in the exhaust gas swirl direction, the amount of protrusion to the inside of the expansion chamber decreases.

According to the first aspect of the present invention, the expansion chamber which is reduced again after the passage area is enlarged is formed downstream of the exhaust gas purification means of the exhaust passage, and one end of the exhaust gas introduction path of the exhaust gas recirculation means is provided on the outer periphery of the expansion chamber. The exhaust passage is connected so as to communicate with the exhaust passage, and the other end is connected downstream of the intake pressure adjusting means of the intake passage so as to communicate with the intake passage.
Thus, by forming an expansion chamber in the exhaust passage and enlarging the inner diameter of the exhaust gas flow path, the pressure in the expansion chamber can be increased with respect to the pressure in the exhaust passage before the expansion chamber.

Therefore, by connecting one end of the exhaust gas introduction passage to the expansion chamber, it is not necessary to increase the pressure inside the exhaust passage by using an exhaust shutter or the like to increase the amount of exhaust gas introduced into the intake passage. The pumping loss due to the increase in exhaust gas pressure can be reduced, so that the cost can be reduced and the fuel consumption can be improved.
In addition, by connecting one end of the exhaust gas introduction path to the expansion chamber, for example, even if the opening of a valve or the like for adjusting the amount of exhaust gas recirculation means introduced into the intake passage is the same, the pressure in the expansion chamber The amount of exhaust gas introduced into the intake passage can be increased due to the high value.

Therefore, if the amount of exhaust gas introduced into the intake passage is the same, the pressure in the intake passage to which the other end of the exhaust gas introduction passage by the intake pressure adjusting means for increasing the amount of exhaust gas introduced into the intake passage is connected is adjusted. Since it can suppress that it reduces, the pumping loss of an internal combustion engine can be reduced and a fuel consumption can be improved further.
According to the invention of claim 2, swirl flow generating means for generating swirl flow in the exhaust gas in the exhaust passage is disposed in the exhaust passage between the exhaust purification means and the expansion chamber. By generating a swirling flow in the inflowing exhaust gas, the exhaust gas can be guided to the outer peripheral portion of the expansion chamber by the inertial force due to the swirling flow, so that it becomes easier to introduce the exhaust gas into the exhaust gas introduction path of the exhaust gas recirculation means, and the intake passage The amount of exhaust gas introduced into can be increased.

Therefore, if the amount of exhaust gas introduced into the intake passage is the same, the pressure in the intake passage to which the other end of the exhaust gas introduction passage by the intake pressure adjusting means for increasing the amount of exhaust gas introduced into the intake passage is connected is adjusted. Since it can suppress that it reduces, the pumping loss of an internal combustion engine can be reduced and a fuel consumption can be improved further.
According to the invention of claim 3, one end of the exhaust gas introduction path extends to the outer peripheral part of the expansion chamber so that the exhaust gas introduction path extends from the outer peripheral part of the expansion chamber toward the front side in the exhaust gas swirling direction of the exhaust gas swirl flow. Since it is easy to introduce the exhaust gas guided to the outer periphery of the expansion chamber directly into the exhaust gas introduction path of the exhaust gas recirculation means due to the inertial force due to the swirling flow, the amount of exhaust gas introduced into the intake passage can be increased. it can.

  According to the invention of claim 4, the inner wall surface of the expansion chamber, which is the inner side of the connection portion to which one end of the exhaust gas introduction path of the outer peripheral portion of the expansion chamber is connected, protrudes to the inside of the expansion chamber, so The projecting amount is reduced to the inside of the expansion chamber as it goes, and exhaust gas that is a swirling flow is guided to the exhaust gas introduction path, so that it becomes easier to introduce the exhaust gas into the exhaust gas introduction path of the exhaust gas recirculation means. The amount introduced can be further increased.

1 is a schematic configuration diagram of an engine to which an EGR device for an internal combustion engine according to the present invention is applied. It is an enlarged view of the perspective view of the A section of FIG. It is an enlarged view of the cross section in the BB line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an engine to which an EGR device for an internal combustion engine is applied. FIG. 2 is an enlarged view of a perspective view of a portion A in FIG. In addition, the upper side of FIG. 2 shows the upstream in the exhaust gas flow direction, and the lower side shows the downstream in the exhaust gas flow direction. FIG. 3 is an enlarged view of a cross section taken along line BB in FIG. The white arrow in FIG. 3 shows the flow direction of exhaust gas.

As shown in FIG. 1, an engine (internal combustion engine) 1 is a multi-cylinder direct injection internal combustion engine (for example, a common rail diesel engine). Specifically, high pressure fuel accumulated in the common rail is used as fuel for each cylinder. The fuel nozzle is supplied to the injection nozzle 2 and can be injected from the fuel injection nozzle 2 into the combustion chamber 3 of each cylinder at an arbitrary injection timing and injection amount.
Each cylinder of the engine 1 is provided with a piston 4 that can slide up and down. The piston 4 is connected to the crankshaft 6 via a connecting rod 5. Further, a flywheel (not shown) is provided at one end of the crankshaft 6.

An intake port 8 and an exhaust port 9 are communicated with the combustion chamber 3.
The intake port 8 is provided with an intake valve 10 for communicating and blocking between the combustion chamber 3 and the intake port 8. In addition, the exhaust port 9 is provided with an exhaust valve 11 for performing communication and blocking between the combustion chamber 3 and the exhaust port 9.

An intake manifold 12 that distributes the intake air to each cylinder is provided upstream of the intake port 8 so as to communicate therewith.
The intake manifold 12 and the exhaust manifold 16 are provided with a high-pressure EGR passage 17 for returning a part of the high-temperature / high-pressure exhaust gas to the intake air, that is, for introducing the high-temperature / high-pressure EGR gas into the intake air so as to communicate with each other. . The high-pressure EGR passage 17 is connected to the intake manifold 12 via an EGR valve 18 that adjusts the amount of high-pressure exhaust gas that returns to the intake air, that is, the flow rate of EGR gas. The high-pressure EGR passage 17 is provided with an EGR cooler 19 that cools the exhaust gas introduced into the intake manifold 12.

  Upstream of the intake manifold 12 is an air cleaner 22 that removes fresh air sucked from the uppermost stream, and an electronically controlled throttle valve that controls the amount of low-temperature and low-pressure EGR gas by adjusting the amount of intake air (intake pressure). (Adjustment means) 25, a compressor housing (not shown) of the turbocharger 23 that compresses the fresh air sucked using the energy of the exhaust gas, and an intercooler 24 that cools the hot fresh air that has been compressed and is heated. It is connected to the intake manifold 12 via a passageway 27. An electronically controlled throttle valve 26 for adjusting the flow rate of high-temperature EGR gas introduced from the high-pressure EGR passage 17 is disposed between the intake pipe 27 and the intake manifold 12.

Downstream of the exhaust port 9, an exhaust manifold 16 that collects exhaust gas discharged from each cylinder, a turbine housing (not shown) that introduces exhaust gas into the turbocharger 23, and an exhaust pipe (exhaust passage) 32 are provided in communication with each other. It has been.
The exhaust pipe 32 is mainly composed of an oxidation catalyst (exhaust purification means) 33 that oxidizes components to be oxidized such as hydrocarbon (THC) or carbon monoxide (CO) in the exhaust gas in order from upstream and graphite in the exhaust gas. A diesel particulate filter (exhaust gas purification means) 34 that collects and combusts particulate matter (PM) to be combusted is provided. Further, in the exhaust pipe 32 downstream of the diesel particulate filter 34, a swirl flow generator (swirl flow generating means) as shown in FIG. 2 is formed so that the swirl flow swirls around the exhaust gas flow direction. ) 35 is provided. An expansion chamber 36 having an inner diameter larger than the inner diameter of the exhaust pipe 32 is formed in the exhaust pipe 32 downstream of the swirl flow generator 35 as shown in FIG.

As shown in FIG. 2, the swirling flow generating device 35 is provided with a plurality (eight in this embodiment) of blade portions 35 a so as to spread radially from the central portion of the exhaust pipe 32. The blade portion 35a is formed such that a portion on the outer peripheral side is curved in the swirl direction when disposed in the expansion chamber 35 on the downstream side in the exhaust gas flow direction.
As shown in FIG. 3, a low-pressure EGR passage (exhaust gas recirculation means for returning a part of the low-temperature / low-pressure exhaust gas to the intake air downstream of the electronic control throttle valve 25, that is, introducing low-temperature / low-pressure EGR gas into the intake air. , The exhaust pipe 32 and the intake pipe 27 communicate with each other, and the one end 38a of the low pressure EGR passage 38 extends in the expansion chamber 36 so that the low pressure EGR passage 38 extends toward the front side in the exhaust gas swirling direction. It is connected to the outer periphery. Further, the inner wall surface 36a of the expansion chamber 36 protrudes to the inside of the expansion chamber 36 so that the inner side of the connection portion 36b to which one end 38a of the low pressure EGR passage 38 is connected extends toward the anti-low pressure EGR passage 38, and the swirling of the exhaust gas. It is formed so that the amount of protrusion to the inside of the expansion chamber 36 decreases as it goes in the direction.

The other end 38 b of the low pressure EGR passage 38 is connected to the intake pipe 27 downstream of the electronic control throttle valve 25. The low-pressure EGR passage 38 is provided with an EGR valve (exhaust gas recirculation means) 39 for adjusting the amount of exhaust gas returning to the intake air, that is, the flow rate of EGR gas, and an EGR cooler 40 for cooling the exhaust gas returning to the intake air. .
As described above, the EGR device for an internal combustion engine according to the present invention makes the exhaust gas flow into the exhaust pipe 32 downstream of the diesel particulate filter 34, as shown in FIG. A swirl flow generator 35 is provided. An expansion chamber 36 having an inner diameter larger than the inner diameter of the exhaust pipe 32 is formed in the exhaust pipe 32 downstream of the swirl flow generator 35 as shown in FIG. As shown in FIG. 3, one end 38 a of the low pressure EGR passage 38 is connected to the outer peripheral portion of the expansion chamber 36 so that the low pressure EGR passage 38 extends toward the front side in the exhaust gas swirl direction. Further, the inside wall surface 36a of the expansion chamber 36 protrudes inside the expansion chamber 36 so that the inside of the connecting portion 36b to which one end 38a of the low pressure EGR passage 38 is connected extends toward the anti-low pressure EGR passage 38, and the swirl direction of the exhaust gas. The amount of protrusion to the inner side of the expansion chamber 36 is reduced as it goes to.

In this way, by forming the expansion chamber 36 in the exhaust pipe 32 and expanding the inner diameter of the exhaust gas flow path, the pressure in the expansion chamber 36 is increased with respect to the pressure in the exhaust pipe 32 before the expansion chamber 36. Can do.
Therefore, by connecting one end 38a of the low pressure EGR passage 38 to the expansion chamber 36, it is not necessary to increase the total pressure in the exhaust pipe 32 using an exhaust shutter or the like to increase the amount of exhaust gas introduced into the intake pipe 27. Therefore, the exhaust shutter and the like can be eliminated, and the pumping loss due to the increase in the exhaust gas pressure can be reduced. Therefore, the cost can be reduced and the fuel consumption can be improved.

Further, by connecting one end 38a of the low pressure EGR passage 38 to the expansion chamber 36, for example, even if the opening degree of the EGR valve 39 is the same, the exhaust gas to the intake pipe 27 is increased due to the high pressure in the expansion chamber 36. The introduction amount of can be increased.
Therefore, if the amount of exhaust gas introduced into the intake pipe 27 is the same, it is possible to suppress the pressure in the intake pipe 27 to which the other end 38b of the low pressure EGR passage 38 is connected by the electronic control throttle valve 25 from being reduced. Therefore, the pumping loss of the engine 1 can be reduced, and the fuel consumption can be further improved.

  Further, a swirl flow generator 35 that generates a swirl flow in the exhaust gas in the exhaust pipe 32 is disposed in the exhaust pipe 32 between the diesel particulate filter 34 and the expansion chamber 36, and flows into the expansion chamber 36. By generating a swirling flow in the exhaust gas to be discharged, the exhaust gas can be guided to the outer peripheral portion of the expansion chamber 36 by the inertial force due to the swirling flow, so that it becomes easier to introduce the exhaust gas into the low pressure EGR passage 38 and the exhaust gas to the intake pipe 27 The amount introduced can be increased.

  Therefore, if the introduction amount of the exhaust gas to the intake pipe 27 is the same, the intake air to which the other end 38b of the low pressure EGR passage 38 by the electronic control throttle valve 25 for increasing the introduction amount of the exhaust gas to the intake pipe 27 is connected. Since it is possible to suppress the pressure in the pipe 27 from being lowered, the pumping loss of the engine 1 can be reduced and the fuel consumption can be further improved.

Further, one end 38a of the low pressure EGR passage 38 is connected to the outer peripheral portion of the expansion chamber 36 so that the low pressure EGR passage 38 extends toward the front side in the exhaust gas swirling direction. Since the exhaust gas guided to the outer peripheral portion can be easily introduced directly into the low pressure EGR passage 38, the amount of exhaust gas introduced into the intake pipe 27 can be increased.
Further, the inner wall surface 36a of the expansion chamber 36 protrudes inside the expansion chamber 36 so that the inner side 36b of the connecting portion to which one end 38a of the low pressure EGR passage 38 is connected extends toward the anti-low pressure EGR passage, and in the swirling direction of the exhaust gas. The amount of protrusion to the inside of the expansion chamber 36 is reduced as it goes, and the exhaust gas, which is a swirling flow, is guided to the low pressure EGR passage 38, so that it can be easily introduced into the low pressure EGR passage 38. The amount of exhaust gas introduced into 27 can be further increased.

This is the end of the description of the embodiment of the invention, but the invention is not limited to this embodiment.
The formation of the expansion chamber 36, the arrangement of the swirling flow generator 35, the connection position of the low pressure EGR passage 38 to the expansion chamber 36, and the formation of the inner wall surface 36a of the expansion chamber 36 are performed simultaneously. It is not necessary to carry out each of them simultaneously. For example, even if the expansion chamber 36 is formed in the exhaust pipe 32 and only the low pressure EGR passage 38 is connected to the outer peripheral portion of the expansion chamber 36, the effect of forming the expansion chamber 36 can be obtained. Can do.

  Further, the wing portion 35a of the swirl flow generator 35 is formed so that the portion on the outer peripheral side is curved in the swirl direction when disposed in the expansion chamber 35 on the downstream side in the exhaust gas flow direction. Needless to say, the shape of the airfoil is not limited to the shape of the wing, and the flow of the exhaust gas is a swirling flow.

1 engine (internal combustion engine)
25 Electronically controlled throttle valve (intake pressure adjustment means)
27 Intake pipe (intake passage)
32 Exhaust pipe (exhaust passage)
33 Oxidation catalyst (exhaust gas purification means)
34 Diesel particulate filter (exhaust gas purification means)
35 Swirl flow generator (Swirl flow generator)
36 Expansion chamber 38 Low pressure EGR passage (exhaust gas recirculation means, exhaust gas introduction passage)
39 EGR valve (exhaust gas recirculation means)

Claims (4)

Exhaust gas purification means for purifying exhaust gas discharged from the internal combustion engine is disposed, and an exhaust passage in which an expansion chamber is formed downstream of the exhaust gas purification means and which is reduced again after the passage area is enlarged,
An intake passage for introducing air into the internal combustion engine;
One end is connected to the outer peripheral portion of the expansion chamber of the exhaust passage so as to communicate with the exhaust passage, and the other end has an exhaust gas introduction path connected to the intake passage so as to communicate with the intake passage, An exhaust gas recirculation means for adjusting the amount of the exhaust gas introduced into the intake passage and recirculating the exhaust gas into the intake passage;
The exhaust gas is disposed upstream of the connection portion at the other end of the exhaust gas introduction path of the intake passage, and the pressure in the intake passage at the connection portion at the other end of the exhaust gas introduction path is adjusted to adjust the introduction amount of the exhaust gas. An EGR device for an internal combustion engine, comprising: an intake pressure adjusting means.   2. The EGR of the internal combustion engine according to claim 1, wherein swirl flow generating means for generating swirl flow in the exhaust gas is disposed in the exhaust passage between the exhaust purification unit and the expansion chamber. apparatus.   The one end of the exhaust gas introduction path is connected to the outer peripheral part of the expansion chamber so that the exhaust gas introduction path extends from the outer peripheral part of the expansion chamber toward the front side in the exhaust gas swirling direction of the swirling flow of the exhaust gas. The EGR device for an internal combustion engine according to claim 2, wherein:   As for the inner wall surface of the expansion chamber, the inside of the connection portion to which the one end of the exhaust gas introduction path is connected protrudes to the inside of the expansion chamber, and the amount of protrusion to the inside of the expansion chamber increases in the exhaust gas swirling direction. The EGR device for an internal combustion engine according to claim 3, wherein the EGR device is configured to decrease.

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