阅读说明：本技术 排气再循环装置及内燃机 (Exhaust gas recirculation device and internal combustion engine ) 是由 饭田真 于 2018-04-09 设计创作，主要内容包括：本发明提供能够防止冷凝水被送向进气通道的排气再循环装置及内燃机。排气再循环装置具备：EGR通道,使废气从内燃机的排气通道向进气通道再循环；EGR冷却器,设置于EGR通道,对废气进行冷却；以及冷凝水处理部,该冷凝水处理部包括通道,该通道将EGR通道中的比EGR冷却器更靠下游侧的位置与比EGR冷却器更靠上游侧的位置连结,并使通过废气的冷却而产生的冷凝水从下游侧向上游侧返回。(the invention provides an exhaust gas recirculation device and an internal combustion engine capable of preventing condensed water from being sent to an air inlet channel. The exhaust gas recirculation device is provided with: an EGR passage that recirculates exhaust gas from an exhaust passage to an intake passage of the internal combustion engine; an EGR cooler provided in the EGR passage and cooling the exhaust gas; and a condensed water treatment unit including a passage that connects a position on a downstream side of the EGR passage with a position on an upstream side of the EGR cooler, and that returns condensed water generated by cooling of the exhaust gas from the downstream side to the upstream side.)

1. An exhaust gas recirculation device is provided with:

An exhaust gas recirculation passage that recirculates exhaust gas from an exhaust passage to an intake passage of the internal combustion engine;

an exhaust gas recirculation cooler provided in the exhaust gas recirculation passage and cooling the exhaust gas; and

And a condensate water treatment unit including a passage that connects a position on a downstream side of the exhaust gas recirculation passage with a position on an upstream side of the exhaust gas recirculation cooler, and that returns condensate water generated by cooling the exhaust gas from the downstream side to the upstream side.

2. The exhaust gas recirculation apparatus according to claim 1,

The height in the vehicle vertical direction is different between the end portion on the upstream side of the passage and the end portion on the downstream side of the passage.

3. The exhaust gas recirculation apparatus according to claim 1,

The condensed water treatment unit has a reservoir for storing the condensed water.

4. The exhaust gas recirculation apparatus according to claim 3,

The reservoir portion is provided at a position downstream of the egr cooler in the egr passage.

5. The exhaust gas recirculation apparatus according to claim 4,

The ratio of the cross-sectional area of the condensate passage to the cross-sectional area of the egr cooler is equal to or less than a predetermined ratio that is predetermined so that the temperature of the exhaust gas flowing through the intake passage is within an allowable range.

6. An internal combustion engine provided with the exhaust gas recirculation device according to claim 1.

Technical Field

The present invention relates to an exhaust gas recirculation device and an internal combustion engine.

Background

Conventionally, an internal combustion engine is sometimes equipped with an Exhaust Gas Recirculation device that supplies a part of Exhaust Gas discharged to an Exhaust passage to an intake passage as EGR (Exhaust Gas Recirculation) Gas.

The exhaust gas recirculation apparatus reduces the combustion temperature to reduce nitrogen oxides in exhaust gas and improves the filling rate of EGR gas into the cylinder by cooling the EGR gas with an EGR cooler.

Disclosure of Invention

Problems to be solved by the invention

However, for example, at a low water temperature before warm-up or at a low EGR gas temperature due to a partial load after warm-up, moisture in the EGR gas is condensed in the EGR cooler, and nitrogen oxides and sulfur oxides in the EGR gas come into contact with the condensed portion to generate strongly acidic condensed water. There are the following problems: when the strongly acidic condensed water generated is sent to the intake passage, parts of the internal combustion engine connected to the intake passage may be corroded.

The invention provides an exhaust gas recirculation device and an internal combustion engine capable of preventing condensed water from being sent to an air inlet channel.

Means for solving the problems

The exhaust gas recirculation device of the present invention includes:

An EGR passage that recirculates exhaust gas from an exhaust passage to an intake passage of the internal combustion engine;

an EGR cooler that is provided in the EGR passage and cools exhaust gas; and

and a condensed water treatment unit including a passage that connects a position on a downstream side of the EGR passage with a position on an upstream side of the EGR cooler, and that returns condensed water generated by cooling the exhaust gas from the downstream side to the upstream side.

The internal combustion engine of the present invention is provided with the above exhaust gas recirculation device.

Effects of the invention

According to the present invention, the condensed water can be prevented from being sent to the intake passage.

Drawings

Fig. 1 is a diagram showing an example of an engine including an exhaust gas recirculation device according to an embodiment of the present invention.

Fig. 2 is a diagram showing an example of the exhaust gas recirculation device according to the present embodiment.

Fig. 3A is a diagram showing an exhaust gas recirculation device according to modification 1 of the present embodiment.

Fig. 3B is a diagram showing an exhaust gas recirculation device according to modification 2 of the present embodiment.

Fig. 3C is a diagram showing an exhaust gas recirculation device according to modification 3 of the present embodiment.

Detailed Description

An embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a diagram showing an example of an engine 10 including an exhaust gas recirculation device 100.

In the engine 10, the intake air a1 drawn into the intake passage 11 is compressed by a compressor 12a of a Turbocharger (turbo charger)12 to have a high temperature, and is cooled by an intercooler 13. Then, the intake air a1 is supplied to the cylinders 16 of the engine block 15 through the intake manifold 14. The intake air a1 supplied to the cylinder 16 is mixed with fuel injected from a fuel injection valve (not shown) and burned to generate thermal energy, and then becomes exhaust gas G1.

The exhaust gas G1 is discharged to the exhaust passage 19 via the exhaust manifold 18, and drives the turbine 12b of the turbocharger 12. After that, the exhaust gas G1 is purified by the exhaust gas purification device 20 and then released into the atmosphere.

A portion of the exhaust gas G1 is recirculated from the exhaust passage 19 to the intake passage 11 as EGR gas G2 by the exhaust gas recirculation apparatus 100.

The exhaust gas recirculation apparatus 100 includes an EGR passage 31 and an EGR cooler 32.

the EGR passage 31 is a passage that branches from a position midway in the exhaust passage 19 and is connected to a position midway in the intake passage 11. The branching point between the EGR passage 31 and the exhaust passage 19 is disposed upstream of the exhaust gas purification device 20 in the exhaust passage 19.

The EGR cooler 32 is a cooler that exchanges heat with the cooling water C1 (see fig. 2) when the EGR gas G2 passing through the EGR passage 31 passes through the inside thereof. In the EGR cooler 32, the moisture in the EGR gas G2 condenses into a droplet or mist. Nitrogen oxides or sulfur oxides in the EGR gas G2 come into contact therewith, whereby strongly acidic condensed water is produced.

For example, when driving in an urban area, the EGR gas G2 has a low temperature, and therefore condensed water is likely to be generated. In recent years, the EGR rate tends to be higher in order to further reduce nitrogen oxides in the exhaust gas and further increase the filling rate of the EGR gas G2 into the cylinder 16. Since a certain amount of moisture is contained in the exhaust gas G1, the amount of moisture in the EGR gas G2 increases as the EGR rate increases. Thus, there is a tendency that: the moisture in the EGR gas G2 is easily condensed, and the strongly acidic condensed water generated increases.

The strongly acidic condensed water generated is sent to the intake passage 11 on the downstream side of the EGR cooler 32, passes through the intake manifold 14 (see fig. 2), and may corrode parts of the cylinder (not shown) while flowing through the cylinder. In this case, for example, the sealing performance of an intake valve (not shown) may be reduced, and the performance may be reduced because the explosion pressure in the cylinder cannot be maintained. Further, for example, an injection nozzle (not shown) may be corroded, and the spray state of the fuel may be deteriorated. In addition, for example, there is a possibility that corrosion and wear in the cylinder are increased to significantly deteriorate the performance and durability.

further, if an engine (not shown) is provided with a compressor (not shown) on the downstream side of the EGR cooler 32, the compressor may be damaged by thermal shock when the compressor comes into contact with the condensed water and cools quickly.

In order to prevent condensed water from being sent to the intake passage 11 side, the exhaust gas recirculation apparatus 100 of the present embodiment includes a condensed water treatment unit 30. Here, the "intake passage" refers to an intake system including a compressor of a turbocharger and an intake manifold.

fig. 2 is a diagram showing an example of the exhaust gas recirculation apparatus 100.

As shown in fig. 2, the condensate water treatment unit 30 includes a condensate water passage 33 and a reservoir 34 in order to return condensate water from the downstream side 31L to the upstream side 31U.

As shown in fig. 1 and 2, the condensate passage 33 connects a position on the downstream side 31L of the EGR passage 31 with respect to the EGR cooler 32 and a position on the upstream side 31U of the EGR cooler 32. The condensate passage 33 has a pipe member 33A. One end 33B of the pipe member 33A is connected to the downstream side 31L. The other end 33C of the pipe member 33A is connected to the upstream side 31U.

In the case where there is no condensed water in the condensed water treatment portion 30 (the pipe member 33A or the reservoir portion 34), the EGR gas sent from the upstream side 31U to the downstream side 31L through the condensed water treatment portion 30 without passing through the EGR cooler 32 and the EGR gas sent from the upstream side 31U to the downstream side 31L through the EGR cooler 32 are supplied to the intake passage 11.

The temperature of the EGR gas G2 supplied to the intake passage 11 rises as the ratio of the cross-sectional area of the pipe member 33A to the cross-sectional area of the EGR cooler 32 becomes larger. Therefore, the ratio of the cross-sectional area of the pipe member 33A to the cross-sectional area of the EGR cooler 32 is controlled to be equal to or less than a predetermined ratio determined in advance so that the cooled temperature of the EGR gas G2 (i.e., the temperature of the EGR gas G2 flowing through the intake passage 11) falls within the allowable range.

As shown in fig. 2, the reservoir 34 is provided in a collection area where the condensed water on the downstream side 31L is concentrated, and has a function of accumulating a predetermined amount of the concentrated condensed water. Thereby preventing the condensed water from being sent to the intake passage 11 side. The storage portion 34 is connected to one end 33B of the tube member 33A.

As shown in fig. 2, a difference h in height in the vehicle vertical direction is provided between the upper end of the reservoir portion 34 and the center axis of the pipe member 33A at the other end 33C of the pipe member 33A. The drop height h is set so that the condensate is returned from the downstream side 31L to the upstream side 31U when the loss resistance between the upstream side 31U and the downstream side 31L is smaller than a predetermined value. The pipe member 33A extends from the downstream side 31L to the upstream side 31U at a predetermined angle θ with respect to the horizontal direction.

The relationship between the loss resistance (pressure loss) Δ P and the head difference h of the EGR cooler 32 will be described below.

The lost resistance Δ P of the EGR cooler 32 is proportional to the pipeline friction coefficient λ, the channel length L, the gas density ρ, and the square of the gas velocity V, and inversely proportional to the channel effective tube equivalent diameter d.

Which is represented by the following formula (1).

ΔP＝λLρV/2d…(1)

According to the above equation (1), if the rotation speed of the engine 10 is increased from Ne1[ rpm ] to Ne2[ rpm ] and the speed of the EGR gas becomes 4 times, the loss resistance of the EGR cooler 32 becomes 16 times. For example, when the loss resistance of the EGR cooler 32 at the rotation speed Ne2 is Δ P2[ mmAq ], the loss resistance at the rotation speed Ne1 becomes Δ P1(═ Δ P2/16) [ mmAq ].

for example, a difference h of L (═ Δ P1) [ mm ] or more is provided in the vehicle vertical direction between the upper end of the storage portion 34 and the center axis of the pipe member 33A at the other end 33C of the pipe member 33A. In other words, the pressure obtained by adding the head pressure at the reservoir 34 and the head pressure at the tube member 33A is set to Δ P1[ mmAq ] or more.

at this time, when the rotation speed of engine 10 is less than Ne1[ rpm ] (for example, during urban driving), the head pressure after the addition is greater than the loss resistance, and therefore, the condensed water flows from one end 33B to the other end 33C of pipe member 33A. Further, the condensed water flowing to the other end 33C evaporates on the upstream side 31U on the high temperature side.

Next, an example of the operation of the exhaust gas recirculation device 100 will be described.

In the following description, a difference h of L [ mm ] or more is provided between the upper end of the reservoir 34 and the other end 33C of the pipe member 33A.

In such an engine 10, a part of the exhaust gas G1 is recirculated as EGR gas G2 from the exhaust passage 19 to the intake passage 11 through the EGR passage 31. The EGR gas G2 is cooled by the EGR cooler 32 while passing through the EGR passage 31.

That is, the cooled EGR gas G2 is supplied to the cylinders 16 of the engine body 15 through the intake manifold 14 together with the intake air a1 cooled by the intercooler 13. The EGR cooler 32 cools the EGR gas G2 to reduce nitrogen oxides in the exhaust gas, and the filling rate of the EGR gas G2 into the cylinders 16 is increased.

The moisture in the EGR gas is cooled by the EGR cooler 32 to be condensed into a droplet shape or a mist shape. Nitrogen oxides and the like in the EGR gas come into contact with this, whereby strongly acidic condensed water is generated. The generated condensed water is accumulated in the reservoir portion 34.

When the engine 10 rotates at a speed less than Ne1 rpm, for example, during urban driving of the vehicle, the loss resistance between the downstream side 31L and the upstream side 31U of the EGR passage 31 is less than Δ P1 mmAq, and therefore, in the condensed water treatment unit 30 having a difference h of L (═ Δ P1) [ mm ] or more, the condensed water flows from the reservoir 34 to the upstream side 31U through the pipe member 33A. Then, the condensed water is evaporated by the heat of the upstream side 31U.

That is, the condensed water is accumulated in the reservoir 34, for example, when the EGR gas temperature is low during low water temperature before warm-up or during partial load operation, or when the EGR rate is high. Since the condensed water accumulated in the reservoir 34 flows to the upstream side 31U during urban traveling, the condensed water does not overflow from the reservoir 34 and is not sent to the intake passage 11 side. This prevents the condensed water from corroding parts of the internal combustion engine connected to the intake passage 11.

< effects of the present embodiment >

As described above, the exhaust gas recirculation device 100 according to the present embodiment includes: an EGR passage 31 that recirculates exhaust gas from the exhaust passage 19 of the engine 10 to the intake passage 11; an EGR cooler 32 provided in the EGR passage 31 and cooling the exhaust gas; and a condensed water processing unit 30, the condensed water processing unit 30 including a condensed water passage 33, the condensed water passage 33 connecting a position on a downstream side 31L of the EGR passage 31 with respect to the EGR cooler 32 and a position on an upstream side 31U of the EGR cooler 32, and returning condensed water generated by cooling of the exhaust gas from the downstream side 31L to the upstream side 31U. Thus, the condensed water generated by cooling the exhaust gas flows from the downstream side 31L to the upstream side 31U, and is evaporated by obtaining heat from the upstream side 31U, so that the condensed water can be prevented from being sent to the intake passage 11.

In addition, according to the exhaust gas recirculation device 100 of the present embodiment, the condensate water treatment unit 30 has a difference h such that: the condensed water flows when the loss resistance between the upstream side 31U and the downstream side 31L is lower than a predetermined value. Thus, when the loss resistance is smaller than the predetermined value, for example, when traveling in an urban area, the condensed water can be made to flow from the downstream side 31L to the upstream side 31U. Therefore, the condensed water can be prevented from being sent from the downstream side 31L to the intake passage 11.

< modification of the present embodiment >

Next, an exhaust gas recirculation device 100 according to a modification of the above embodiment will be described with reference to fig. 3A to 3C. Fig. 3A to 3C schematically show the upstream side 31U, the downstream side 31L, the pipe member 33A, and the like.

(modification 1)

In the above embodiment, as shown in fig. 2, the one end 33B of the pipe member 33A is indirectly connected to the downstream side 31L of the EGR passage 31 via the storage portion 34. In contrast, in the condensate water treatment unit 30A of modification 1, as shown in fig. 3A, one end 33B of the pipe member 33A is directly connected to the downstream side 31L of the EGR passage 31. At this time, the one end 33B of the pipe member 33A is provided in the collection region where the condensed water in the downstream side 31L concentrates. The pipe member 33A has a function of storing the condensed water concentrated in the collecting region. Further, the difference h is provided between the center axes of the pipe members 33A at the one end 33B and the other end 33C of the pipe members 33A.

(modification 2)

In the above embodiment, as shown in fig. 2, the storage portion 34 is provided on the downstream side 31L of the EGR passage 31. In contrast, in condensate water treatment unit 30B according to modification 2, as shown in fig. 3B, reservoir 34A is provided in pipe member 33A. At this time, the storage portion 34A is provided at an arbitrary position between the one end 33B and the other end 33C of the pipe member 33A. The storage portion 34A may be provided integrally with the tube member 33A or may be provided separately. By providing the reservoir portion 34A and the pipe member 33A integrally, for example, assembly of the condensed water treatment portion 30B to the EGR passage 31 becomes easy.

(modification 3)

In the above embodiment, the pipe member 33A extends in a direction at a predetermined angle θ with respect to the horizontal direction as shown in fig. 2 in order to provide a step h between the upstream side 31U and the downstream side 31L. In contrast, in the condensate water treatment unit 30C of modification 3, as shown in fig. 3C, the pipe member 33A extends in the horizontal direction. The reservoir 34B has a depth corresponding to the height h. One end 33B of the pipe member 33A is connected to the bottom of the storage portion 34B. The reservoir 34B of modification 3 has a sufficient depth corresponding to the drop height h, and is therefore suitable for a case where a large amount of condensed water needs to be accumulated.

The present application is based on the japanese patent application filed on 20/4/2017 (japanese patent application 2017-083646), the content of which is hereby incorporated by reference.

Industrial applicability

The exhaust gas recirculation device for a vehicle according to the present invention is useful as a vehicle including an internal combustion engine that requires prevention of condensed water from being sent to an intake passage.

Description of the reference numerals

10 engines

11 air intake channel

12 turbo charger

12a compressor

12b turbine

13 intercooler

14 air intake manifold

15 Engine body

16 air cylinder

18 exhaust manifold

19 exhaust channel

20 exhaust gas purification device

30 condensed water treatment part

31 EGR passage

31L downstream side

31U upstream side

32 EGR cooler

33 condensate passage

33A pipe member

33B one end

The other end of 33C

34 storage part

34A storage part

34B storage part

100 exhaust gas recirculation device