WO2018110351A1

WO2018110351A1 - Egr cooler

Info

Publication number: WO2018110351A1
Application number: PCT/JP2017/043507
Authority: WO
Inventors: 哲暢鈴木; 豪孝伊藤
Original assignee: 臼井国際産業株式会社
Priority date: 2016-12-16
Filing date: 2017-12-04
Publication date: 2018-06-21
Also published as: JP6730175B2; JP2018096334A

Abstract

The purpose of the present invention is to provide an EGR cooler such that an improvement in separation of liquid contained in EGR gas can be achieved while an increase in device size is suppressed. The EGR cooler has: a heat-exchange unit (21) for cooling EGR gas returning from an exhaust path (3) of an internal combustion engine (1) to an intake path (2); and an outflow pipe (23) providing communication between an exhaust port of the heat-exchange unit (21) and the intake path (2), having therein a swirl flow generation ribbon (30) formed of a helical plate member and causing the EGR gas to swirl, and having an exhaust port (26c) and a drainage port (25c). The swirl flow generation ribbon (30) has a configuration in which first and second edges (32a, 32b) connecting a first end point (31a) set on one radial outer side, a second end point (31b) set on the other radial outer side, and a center end point (31c) disposed on an axis (O) at a position closer to the heat-exchange unit (21) than the first and second end points (31a, 31b) are disposed on an end section (31).

Description

EGR cooler

The present invention relates to an EGR cooler that cools EGR gas that is returned from an exhaust passage of an internal combustion engine to an intake passage.

Conventionally, when part of the exhaust gas is returned as EGR gas from the exhaust passage of the internal combustion engine to the intake passage, an EGR cooler is provided in the EGR pipe through which the EGR gas flows, and the EGR gas is cooled downstream of the EGR cooler. The structure which provided the gas-liquid separator which isolate | separates the liquid produced by doing from gas is known (for example, refer patent document 1, patent document 2, patent document 3).

JP 2016-031042 A JP 2010-090806 A JP 2012-062817 A

However, in the case where the EGR cooler and the gas-liquid separator are installed independently as in the conventional apparatus, a pipe connecting the EGR cooler and the gas-liquid separator is required. In addition, a space for installing the gas-liquid separator must be secured. Therefore, the problem that an apparatus enlarges arises.
On the other hand, as disclosed in Patent Document 1, the end portion of the swirl flow generating ribbon (the end portion on the outflow side of the gas-liquid two-phase fluid) has a linear edge along the radial direction of the pipe. If so, the liquid adhering to the swirl flow generating ribbon may re-scatter into the gas without flowing toward the inner peripheral surface of the pipe at the end of the ribbon. For this reason, the liquid once separated flows again in the gas, and there arises a problem that the liquid separation performance deteriorates.

The present invention has been made paying attention to the above problem, and an object thereof is to provide an EGR cooler capable of improving the separation performance of the liquid contained in the EGR gas while suppressing the enlargement of the apparatus. .

In order to achieve the above object, an EGR cooler according to the present invention includes a heat exchanging portion that exchanges heat between the EGR gas returned from the exhaust passage of the internal combustion engine to the intake passage and the refrigerant, and the intake air of the exhaust passage and the heat exchanging portion. An inflow pipe that communicates with the opening; and an outflow pipe that communicates between the intake passage and the exhaust port of the heat exchange section.
And in the outflow pipe, a swirl flow generating ribbon for swirling EGR gas along the inner peripheral surface is disposed inside, and an exhaust port and a drain port are formed on the downstream side of the swirl flow generating ribbon.
The swirl flow generating ribbon is formed by a spirally twisted plate member, and has a first end point set at one of the radially outer ends of the swirl flow generating ribbon at an end portion facing the exhaust port. The second terminal point set at the other radial outer end of the swirl flow generating ribbon and the axis of the swirl flow generating ribbon, closer to the heat exchange unit than the first terminal point and the second terminal point A first end edge connecting the first end point and the center end point, and a second end edge connecting the second end point and the center end point; Is formed.

Therefore, in the present invention, when the gas-liquid two-phase fluid is swirled to separate the gas and the liquid while suppressing an increase in the size of the apparatus, it is possible to prevent the liquid that is in the form of droplets from flowing together with the gas. .

1 is an overall system diagram illustrating an exhaust gas recirculation system for an internal combustion engine to which an EGR cooler according to a first embodiment is applied. It is sectional drawing which shows the EGR cooler of Example 1. FIG. It is a perspective view which shows the swirl | vortex flow generation | occurrence | production ribbon of Example 1. FIG. It is a side view of the swirl flow generation ribbon of Example 1. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is explanatory drawing which shows the flow of the EGR gas in the EGR cooler of Example 1, and the isolate | separated gas and liquid. In the EGR cooler of Example 1, it is explanatory drawing which shows the flow of the liquid in the ribbon termination | terminus part of the liquid adhering to a swirl | vortex flow generation | occurrence | production ribbon.

Hereinafter, the form for implementing the EGR cooler of this invention is demonstrated based on Example 1 shown in drawing.

Example 1
First, the configuration of the EGR cooler in the first embodiment will be described by dividing it into “the overall system configuration of the application example”, “the detailed configuration of the EGR cooler”, and “the detailed configuration of the swirling flow generating ribbon”.

[System overall configuration of application example]
FIG. 1 is an overall system diagram illustrating an exhaust gas recirculation system for an internal combustion engine to which an EGR cooler according to a first embodiment is applied. The overall system configuration of an application example of the first embodiment will be described below with reference to FIG.

The EGR cooler 20 of the first embodiment is applied to the exhaust gas recirculation system S of the internal combustion engine 1 shown in FIG. Here, the internal combustion engine 1 shown in FIG. 1 is a diesel engine mounted on a vehicle as a driving source for traveling, and has four cylinders (not shown). An intake passage 2 and an exhaust passage 3 are connected to each cylinder.

The intake passage 2 is formed with an intake port 2a at an end, and in order from the intake port 2a side, an air filter 4 for intake filtration, a compressor 5a of a turbocharger 5, an intercooler 6 for cooling intake air, and intake air A throttle valve 7 for adjusting the amount is provided. In the exhaust passage 3, a turbine 5b of the turbocharger 5, an exhaust purification catalyst 8 for purifying exhaust, and an exhaust throttle valve 9 for adjusting the exhaust flow rate are provided in this order from the internal combustion engine 1 side. A muffler 10 is provided on the downstream side of the exhaust throttle valve 9, and an exhaust port 3a is formed at the end thereof.

The intake passage 2 and the exhaust passage 3 are connected by a low pressure EGR passage 11 and a high pressure EGR passage 12. Here, “EGR (Exhaust Gas Recirculation)” is a technique in which a part of exhaust gas after combustion in the internal combustion engine 1 is taken out and re-intaked, and is also referred to as exhaust gas recirculation.

The low pressure EGR passage 11 connects the intake passage 2 upstream of the compressor 5 a and the exhaust passage 3 downstream of the exhaust purification catalyst 8. On the other hand, the high pressure EGR passage 12 connects the intake passage 2 downstream of the compressor 5a and the exhaust passage 3 upstream of the turbine 5b.
Thereby, in the low pressure EGR passage 11, the exhaust gas that has passed through the turbine 5b is returned to the intake air of the compressor 5a. In the high pressure EGR passage 12, the exhaust gas before being sucked into the turbine 5b is returned to the air that has passed through the compressor 5a.

An EGR cooler 20 for cooling the exhaust gas guided to the intake passage 2 is provided in the middle of the low-pressure EGR passage 11, and the intake air is supplied to the downstream position of the EGR cooler 20 via the low-pressure EGR passage 11. A low-pressure EGR valve 14 for adjusting the flow rate of exhaust gas (EGR gas) recirculated to the passage 2 is provided. A high pressure EGR valve 15 for adjusting the flow rate of the exhaust gas recirculated to the intake passage 2 through the high pressure EGR passage 12 is provided at a midpoint of the high pressure EGR passage 12.

[Detailed configuration of EGR cooler]
FIG. 2 is a cross-sectional view illustrating the EGR cooler according to the first embodiment. Hereinafter, based on FIG. 2, the detailed structure of the EGR cooler 20 of Example 1 is demonstrated.

The EGR cooler 20 according to the first embodiment is provided in the middle of the low pressure EGR passage 11 as described above. Here, the position where the EGR cooler 20 is arranged is divided in the EGR pipe constituting the low pressure EGR passage 11, and the EGR cooler 20 is connected to the upstream side EGR pipe 11a and the downstream side as shown in FIG. It is interposed between the EGR pipe 11b. The EGR cooler 20 includes a heat exchange part 21, an inflow pipe 22, and an outflow pipe 23.

As shown in FIG. 2, the heat exchange unit 21 includes a shell 21a, a pair of

core plates

21b and 21c, and a number of tubes 21d.
The shell 21a is a cylindrical hollow tube whose both ends are open, and a pair of

core plates

21b and 21c are attached so as to close the end surface of the shell 21a. Each

core plate

21b, 21c has both ends of a large number of tubes 21d fixed in a penetrating manner, and these numerous tubes 21d extend in the axial direction inside the shell 21a. Each tube 21d is a hollow tube whose both ends are open, and is arranged in a state where there is a gap between the other tube 21d.
Furthermore, a refrigerant inlet 21e connected to the refrigerant introduction pipe 24a and a refrigerant outlet 21f connected to the refrigerant outlet pipe 24b are formed on the peripheral surface of the shell 21a. The refrigerant introduction pipe 24a and the refrigerant outlet pipe 24b are pipes through which a refrigerant that is, for example, engine cooling water (LLC: Long Life Coolant) flows. The inner diameter of the shell 21a is larger than the inner diameter of the low pressure EGR passage 11.

The inflow pipe 22 is a hollow pipe whose both ends are open, and one end 22a is connected to the upstream EGR pipe 11a. The other end 22b of the inflow pipe 22 is formed in a bowl shape that covers the outer end surface of one core plate 21b, and is connected to the end of the EGR gas inflow side of the shell 21a, that is, the intake port of the heat exchange unit 21. Has been. Thus, the inflow pipe 22 communicates the exhaust passage 3 and the intake port of the heat exchange unit 21.

The outflow pipe 23 is a middle space that is open at both ends, and has an inlet pipe 25, an inner pipe 26, and a drain pipe 27.

The inlet pipe 25 is a hollow tube whose both ends are open, and one end 25a is formed in a bowl shape covering the outer end surface of the other core plate 21c, and the end portion on the outflow side of the EGR gas of the shell 21a, that is, heat exchange It is connected to the exhaust port of the part 21. One end 26 a of the inner pipe 26 is inserted into the other end 25 b of the inlet pipe 25. Further, a drain port 25c opened in the radial direction is formed on the peripheral surface of the other end 25b of the inlet pipe 25.
A swirl flow generating ribbon 30 is disposed inside the inlet pipe 25 to swirl the EGR gas flow along the inner peripheral surface 25d. A tapered surface 25e is formed on the inner peripheral surface 25d of the inlet pipe 25.
The liquid contained in the EGR gas can flow into the drain port 25c by the centrifugal force (swivel force) generated when the EGR gas swirls. Therefore, the opening direction of the drain port 25c is not limited to the downward direction of the gravity direction, and may be opened in any direction.

The tapered surface 25e is an inclined surface that gradually increases the inner diameter dimension of the inlet pipe 25 toward the downstream side in the EGR gas flow direction, and is positioned downstream of the swirling flow generating ribbon 30 in the EGR gas flow direction. Is formed. As a result, the inner diameter of the inlet pipe 25 is the smallest in the first region 25α upstream of the tapered surface 25e in the EGR gas flow direction, and gradually increases in the second region 25β in which the tapered surface 25e is formed. Thus, the third region 25γ, which is downstream of the tapered surface 25e in the EGR gas flow direction, is the largest. And the swirl | vortex flow generation | occurrence | production ribbon 30 is arrange | positioned in the 1st area | region 25 (alpha), and the drain port 25c is formed in the 3rd area | region 25 (gamma).
Note that the inner diameter dimension of the first region 25α where the swirl flow generating ribbon 30 is arranged is set to be smaller than the inner diameter dimension of the heat exchanging portion 21.

The inner pipe 26 is formed by a straight pipe member having both ends open and having an outer diameter smaller than the minimum inner diameter of the third region 25γ of the inlet pipe 25, and one end 26a is inserted into the other end 25b of the inlet pipe 25, It is installed coaxially with the inlet pipe 25. An exhaust port 26c that is open in the axial direction of the inner pipe 26 is formed at the one end 26a. The other end 26b of the inner pipe 26 is connected to the tip of the downstream EGR pipe 11b.
As a result, the outflow pipe 23 communicates the exhaust port of the heat exchanging portion 21 and the intake passage 2 via the inlet pipe 25 and the inner pipe 26.

The other end 25b of the inlet pipe 25 is fitted with a spacer 28 that seals the gap S1 generated between the inner peripheral surface 25d of the inlet pipe 25 and the inner pipe 26. The spacer 28 has a cylindrical shape that surrounds the entire circumference of the inner pipe 26, the outer peripheral surface is in airtight contact with the inner peripheral surface 25 d of the inlet pipe 25, and the inner peripheral surface is in an airtight state with the outer peripheral surface of the inner pipe 26. In contact.
Further, in the spacer 28, the axial position of the end located inside the inlet pipe 25 coincides with the axial position of the most downstream portion of the peripheral edge of the drain port 25 c. That is, although the spacer 28 does not overlap with the opening region of the drain port 25c, the spacer 28 is installed without opening a gap in the axial direction with the opening region of the drain port 25c.

The drain pipe 27 is formed by a so-called T-shaped pipe in which the second pipe member 27b is connected so as to be orthogonal to the central portion in the axial direction of the first pipe member 27a, and the inlet pipe 25 penetrates the first pipe member 27a. Yes. Further, a connection opening 27c formed in a connection portion between the first pipe member 27a and the second pipe member 27b faces the drainage port 25c, and the inlet pipe 25 and the drainage pipe are connected to the drainage port 25c and the connection opening 27c. 27 is communicated with the second pipe member 27b. That is, as described later, the liquid separated from the EGR gas inside the inlet pipe 25 flows into the second pipe member 27b from the drain port 25c through the connection opening 27c.
Here, the inner diameter dimension of the drain port 25 c formed in the inlet pipe 25 is set to be equal to the inner diameter dimension of the connection opening 27 c of the drain pipe 27. The second pipe member 27b extends downward in the gravitational direction with respect to the axial direction of the inlet pipe 25, and a tip opening 27e is formed in the tip portion 27d. Here, the “gravity direction” is the downward direction in FIG. 2 and is the direction in which gravity acts.
The first tube member 27a and the second tube member 27b are not limited to circular tubes, and may be square tubes (square pipes) or the like. In addition, the second tube member 27b shown in FIG. 2 has an intermediate position that gradually becomes thinner toward the distal end portion 27d, and the opening area of the distal end opening 27e is smaller than the opening area of the connection opening 27c. However, the tip opening 27e and the connection opening 27c may have the same size and can be arbitrarily set.

As shown in FIG. 2, a connection port 29 a formed at the upper part in the gravity direction of the water storage tank 29 is connected to the distal end portion 27 d of the second pipe member 27 b. Here, the water storage tank 29 is a tank installed below the second pipe member 27b in the direction of gravity, and stores the liquid that has flowed down the second pipe member 27b.
A drainage opening (not shown) that can be appropriately opened and closed is formed at the lower part of the water storage tank 29 in the direction of gravity. Therefore, in the water storage tank 29, when the stored liquid reaches a certain amount, the stored liquid can be discharged out of the tank through the drain opening.

Further, in the first embodiment, a vent 26d is formed on the side surface of the inner pipe 26 at a position protruding from the inlet pipe 25. The vent 26d is an opening to which one end 29c of the bypass pipe 29b is connected, and is open in the radial direction of the inner pipe 26 and downward in the direction of gravity. A vent hole 29 e is formed on the upper side surface of the water storage tank 29. The vent 29e is an opening to which the other end 29d of the bypass pipe 29b is connected.
Here, the bypass pipe 29b is a pipe member whose both ends are open, and both

end portions

29c and 29d are connected to the vent hole 26d and the vent hole 29e, respectively, so that the space above the water storage tank 29 becomes the inner pipe 26. It communicates with the inside.
In FIG. 2, the vent 26d formed in the inner pipe 26 opens downward in the direction of gravity, but this vent 26d is used to make the water storage tank 29 have a negative pressure via the bypass pipe 29b. Since it is an opening, you may open in directions other than the downward direction of a gravitational direction.

[Detailed configuration of swirl flow generation ribbon]
FIG. 3 is a perspective view showing the swirl flow generating ribbon of Example 1, and FIG. 4 is a side view of the swirl flow generating ribbon. FIG. 5 is a cross-sectional view taken along the line AA in FIG. The detailed configuration of the swirl flow generating ribbon according to the first embodiment will be described below with reference to FIGS.

The swirl flow generating ribbon 30 is formed of a strip-shaped plate member that is spirally twisted, and is disposed in the first region 25α of the inlet pipe 25. The swirl flow generating ribbon 30 has a radial dimension R (see FIG. 4) set to be equal to the inner diameter dimension of the first region 25α, is installed coaxially with the inlet pipe 25, and has a peripheral edge at the inlet pipe 25. In contact with the inner peripheral surface 25d.

The swirling flow generating ribbon 30 has a first terminal point 31a, a second terminal point 31b, and a central terminal point 31c at the terminal part 31 on the outflow side of the EGR gas, and a first edge 32a, And a second end edge 32b.
The first end point 31 a is set to one of the radially outer ends of the swirl flow generating ribbon 30. The second terminal point 31 b is set to the other of the terminal ends on the radially outer side of the swirling flow generating ribbon 30. Here, the axial position of the first terminal point 31a coincides with the axial position of the second terminal point 31b, and the terminal line L connecting the first terminal point 31a and the second terminal point 31b is turned. It is orthogonal to the axis O of the flow generating ribbon 30.
The center terminal point 31c is set on the axis O of the swirling flow generating ribbon 30 and at a position closer to the inflow side of EGR gas than the first terminal point 31a and the second terminal point 31b, that is, closer to the heat exchanging unit 21. Has been.

The first edge 32 a is an edge connecting the first terminal point 31 a and the center terminal point 31 c among the terminal edges of the swirl flow generating ribbon 30. The second end edge 32 b is an end edge connecting the second end point 31 b and the center end point 31 c among the end edges of the swirl flow generating ribbon 30. In other words, the end portion 31 of the swirling flow generating ribbon 30 is provided with a space region cut out in a V shape surrounded by the first end edge 32a, the second end edge 32b, and the end line L.

Further, the swirling flow generating ribbon 30 is formed with a folded structure 33 that is folded on the inflow side of the EGR gas at each of the first end edge 32a and the second end edge 32b.
As shown in FIG. 5, the folded structure 33 includes a first folded piece 33 a in which the tips of the first end edge 32 a and the second end edge 32 b are folded back to the one spiral surface 30 a side of the swirl flow generating ribbon 30, And a second folded piece 33b in which the tips of the end edge 32a and the second end edge 32b are folded back to the opposite spiral surface 30b side. The folded structure 33 is formed between the center terminal point 31c and the first terminal point 31a, and between the center terminal point 31c and the second terminal point 31b. As a result, a gap S2 is generated between both ends in the radial direction of the folded structure 33 and the inner peripheral surface 25d of the inlet pipe 25 (see FIG. 2).

Further, although the swirling flow generating ribbon 30 is disposed in the first region 25α, at least the first terminal point 31a and the second terminal point 31b of the terminal portion 31 are formed with a tapered surface 25e on the inner peripheral surface 25d. Inserted in the second region 25β.

The start end 34 of the swirling flow generating ribbon 30 on the EGR gas inflow side has a first start end point 34a, a second start end point 34b, and a center start end point 34c.
The first starting point 34 a is set to one of the starting ends on the radially outer side of the swirling flow generating ribbon 30. The second starting end point 34 b is set to the other of the starting ends on the radially outer side of the swirling flow generating ribbon 30. The center start end point 34c is on the axis O of the swirling flow generating ribbon 30, and the first start end point 34a and the second start end point 34b coincide with the axial position. That is, the center start point 34c is set on the intersection of the start line connecting the first start point 34a and the second start point 34b and the axis O, and the first and

second start points

34a, 34b and the center start point 34c. Are aligned along the radial direction of the swirl flow generating ribbon 30. Further, the starting end portion 34 of the swirling flow generating ribbon 30 is erected along the direction of gravity.

Next, the operation of the EGR cooler according to the first embodiment will be described by dividing it into “EGR gas cooling operation”, “gas-liquid separation and liquid re-spattering prevention operation”, and “apparatus compacting operation”.

[Cooling action of EGR gas]
FIG. 6 is an explanatory diagram illustrating a gas-liquid two-phase fluid and separated gas / liquid flows in the EGR cooler according to the first embodiment. Hereinafter, based on FIG. 6, the cooling effect | action of the EGR gas in the EGR cooler 20 of Example 1 is demonstrated.

In the exhaust gas recirculation system S shown in FIG. 1, a part of the exhaust gas discharged from the internal combustion engine 1 through the low pressure EGR passage 11 is recirculated from the exhaust passage 3 and merged with the outside air sucked from the intake port 2a. Supplied to the compressor 5a of the feeder 5. At this time, if the high-temperature EGR gas is recirculated, the charging efficiency of the EGR gas in the internal combustion engine 1 is reduced, so that it is difficult to reduce the NOx emission amount. Therefore, before the EGR gas and the outside air are merged, it is necessary to exchange heat between the refrigerant such as engine cooling water and the EGR gas to cool the refluxed EGR gas.

On the other hand, in the EGR cooler 20 of the first embodiment, as shown in FIG. 6, when a part of the exhaust gas flowing through the exhaust passage 3 flows into the low pressure EGR passage 11, the EGR gas that is a part of this exhaust gas is Then, it flows from the upstream EGR pipe 11 a into the inflow pipe 22 of the EGR cooler 20. The other end 22b of the inflow pipe 22 is connected to the end of the EGR gas inflow side of the shell 21a of the heat exchanging portion 21, and the end of the EGR gas inflow side of the shell 21a is connected to one core. While being blocked by the plate 21b, a large number of tubes 21d penetrate the one core plate 21b. The numerous tubes 21d extend in the axial direction inside the shell 21a and penetrate the other core plate 21c that closes the end portion of the shell 21a on the outflow side of the EGR gas.
Therefore, the EGR gas that has flowed into the inflow pipe 22 passes through the shell 21a by passing through the numerous tubes 21d, and the inlet pipe 25 of the outflow pipe 23 from the end of the EGR gas outflow side of the shell 21a. Is discharged.

On the other hand, the shell 21a is formed with a refrigerant inlet 21e connected to the refrigerant introduction pipe 24a and a refrigerant outlet 21f connected to the refrigerant outlet pipe 24b. Therefore, the refrigerant flowing through the refrigerant introduction pipe 24a flows into the shell 21a from the refrigerant inlet 21e, flows through the inside of the shell 21a, and flows out to the refrigerant outlet pipe 24b through the refrigerant outlet 21f.

As described above, the EGR gas flows through the multiple tubes 21d, while the refrigerant flows through the inside of the shell 21a containing the tubes 21d. Therefore, the EGR gas flows outside the tubes 21d while passing through the multiple tubes 21d. It is cooled by heat exchange with the flowing refrigerant. Thereby, the fall of the filling efficiency of the EGR gas in the internal combustion engine 1 can be prevented, and the air ratio can be reduced. Further, the combustion temperature in the internal combustion engine 1 can be lowered. As a result, the NOx emission amount can be reduced.

[Gas-liquid separation and liquid re-spattering prevention]
Hereinafter, based on FIG. 6, the gas-liquid separation and the liquid re-scattering preventing action in the EGR cooler 20 of the first embodiment will be described.

As described above, the high-temperature EGR gas is cooled in the heat exchange unit 21. However, when the EGR gas is cooled, the water contained in the EGR gas becomes liquid as condensed water, and the EGR gas that recirculates to the intake passage 2 becomes a gas-liquid two-phase fluid in which gas and liquid are mixed. Become. In particular, when the heat exchange efficiency in the heat exchange unit 21 is high and the cooling performance is good, the generation of condensed water increases.
Then, when the liquid contained in the gas-liquid two-phase fluid flows downstream in a state of droplets of a certain size, it collides with the rotor blades of the compressor 5a of the turbocharger 5, May cause shock.
On the other hand, in the EGR cooler 20 of the first embodiment, the swirl flow generating ribbon 30 is disposed inside the inlet pipe 25 of the outflow pipe 23 through which the EGR gas in a gas-liquid two-phase fluid state flows.

Therefore, as shown in FIG. 6, the EGR gas flowing into the inlet pipe 25 swirls by flowing along the swirl flow generating ribbon 30 when passing through the first region 25α where the swirl flow generating ribbon 30 is installed. It becomes a flow. And the liquid with a large mass contained in EGR gas is guide | induced toward the internal peripheral surface 25d of the inlet pipe 25 with the centrifugal force provided by this turning flow.

Then, the liquid guided toward the inner peripheral surface 25d of the inlet pipe 25 aggregates into droplets, separates from the gas, and adheres to the inner peripheral surface 25d from the second region 25β by the swirling flow. It flows to the third region 25γ. Then, the liquid flowing into the third region 25γ flows into the drain port 25c formed in the third region 25γ, and flows down the second pipe member 27b through the connection opening 27c of the drain pipe 27 by its own weight. Then, it flows into the water storage tank 29 from the front end opening 27e and is stored.

In the first embodiment, the inner pipe 26 and the water storage tank 29 communicate with each other via the bypass pipe 29b. Therefore, the airflow flowing through the inner pipe 26 can make the inside of the water storage tank 29 have a negative pressure, and the flow of liquid flowing down the drainage pipe 27 can be made smooth. Further, the gas flowing into the water storage tank 29 together with the liquid can be returned to the low pressure EGR passage 11 through the bypass pipe 29b and the inner pipe 26.

The gas flowing through the inlet pipe 25 flows into the inner pipe 26 from the exhaust port 26c opened in the axial direction. Then, this gas flows to the compressor 5 a of the turbocharger 5 through the inner pipe 26.
Here, the outer diameter dimension of the inner pipe 26 is smaller than the inner diameter dimension of the third region 25γ of the inlet pipe 25 in order to be inserted into the inlet pipe 25. Therefore, in the EGR cooler 20 of the first embodiment, the liquid adhering to the inner peripheral surface 25d of the inlet pipe 25 can be prevented from entering the inner pipe 26. Further, the other end 25 b of the inlet pipe 25 is fitted with a spacer 28 that seals the gap S <b> 1 generated between the inlet pipe 25 and the inner pipe 26. Therefore, the EGR cooler 20 can prevent the gas from leaking from the other end 25b of the inlet pipe 25, and can smoothly flow the gas separated from the gas-liquid two-phase fluid into the inner pipe 26.

Meanwhile, the spiral surfaces 30a and 30b of the swirl flow generating ribbon 30 have an angle with respect to the flow direction of the EGR gas. Therefore, the liquid contained in the EGR gas collides with the spiral surfaces 30a and 30b and becomes droplets and adheres to the spiral surfaces 30a and 30b. On the other hand, the liquid in the droplet state attached to the spiral surfaces 30a and 30b of the swirl flow generating ribbon 30 is pushed to the downstream side in the EGR gas flow direction by the swirl flow while remaining attached to the spiral surfaces 30a and 30b. While flowing, it flows toward the radially outer side of the swirling flow generating ribbon 30 and flows along the inner peripheral surface 25 d of the inlet pipe 25. Further, a part of the liquid in the droplet state does not flow to the inner peripheral surface 25d of the inlet pipe 25, but moves to the end portion 31 of the swirling flow generating ribbon 30 while adhering to the spiral surfaces 30a and 30b.

Then, when the liquid in the droplet state that has moved to the end portion 31 of the swirling flow generating ribbon 30 reaches the first end edge 32a or the second end edge 32b, as shown by an arrow in FIG. 7, the first end edge 32a. Alternatively, it flows toward the radially outer side of the swirl flow generating ribbon 30 along the second end edge 32 b and is guided toward the inner peripheral surface 25 d of the inlet pipe 25.

At this time, the first end edge 32 a is more EGR gas than the center end point 31 c where the first end point 31 a located on the radially outer side of the swirling flow generating ribbon 30 is positioned on the axis O of the swirling flow generating ribbon 30. It is located downstream of the flow direction. In addition, the second end edge 32b is such that the second terminal point 31b located on the radially outer side of the swirling flow generating ribbon 30 is more EGR gas than the center terminal point 31c positioned on the axis O of the swirling flow generating ribbon 30. Located downstream in the flow direction.
On the other hand, the liquid adhering to the spiral surfaces 30a and 30b of the swirl flow generating ribbon 30 flows toward the radially outer side of the swirl flow generating ribbon 30 while being swept away by the swirl flow downstream in the EGR gas flow direction. .

Therefore, the extending direction of the first and second end edges 32 a and 32 b substantially coincides with the flow direction (moving direction) of the liquid pushed away by the swirling flow while adhering to the swirling flow generating ribbon 30. Thereby, in the terminal part 31 of the swirling flow generating ribbon 30, the liquid adhering to the spiral surfaces 30a and 30b is maintained in the state of adhering to the first and second end edges 32a and 32b. It moves toward the radially outer side and is guided to the inner peripheral surface 25d of the inlet pipe 25.
That is, even if the swirl flow generating ribbon 30 adheres to the spiral surfaces 30a and 30b and separates from the gas and moves to the terminal portion 31 as it is, the swirl flow generating ribbon 30 does not adhere to the axis O. It can be guided to the inner peripheral surface 25d of the inlet pipe 25 in a state of being attached to the first and second end edges 32a and 32b. Thereby, in the swirl | vortex flow generation | occurrence | production ribbon 30 of Example 1, it can prevent that the liquid isolate | separated from gas re-scatters in gas from the termination | terminus part 31. FIG. And in the EGR cooler 20 of Example 1, while improving the separation performance of a liquid, the collection rate of a liquid can be improved. In addition, since the EGR cooler 20 of Example 1 does not use a baffle, a filter, or the like for liquid separation, the flow of gas is not inhibited and an increase in ventilation resistance can be suppressed.

In addition, the swirling flow generating ribbon 30 of the first embodiment is formed with a folded structure 33 that is folded to the inflow side of the EGR gas at both the first end edge 32a and the second end edge 32b.
Therefore, the liquid that has moved to the first end edge 32a or the second end edge 32b while adhering to the spiral surfaces 30a, 30b is separated from the spiral surfaces 30a, 30b by the folding structure 33 and is downstream in the EGR gas flow direction. Scattering to the side is prevented. That is, the liquid flows radially outward of the swirl flow generating ribbon 30 along the gap between the first end edge 32a and the first folded piece 33a or the gap between the second end edge 32b and the second folded piece 33b. It flows toward you.
As a result, the swirling flow generating ribbon 30 can guide the liquid to the inner peripheral surface 25d of the inlet pipe 25 while preventing the liquid from separating from the first and second end edges 32a and 32b, and from the EGR gas. The liquid separation performance can be further improved.

Further, the folded structure 33 of the first embodiment includes a first folded piece 33a folded on one spiral surface 30a side of the swirling flow generating ribbon 30, and a second folded piece folded on the opposite spiral surface 30b side. 33b.
Therefore, it can be prevented that the liquid is separated from the first and second end edges 32a and 32b regardless of which of the spiral surfaces 30a and 30b of the swirl flow generating ribbon 30 is attached.

The folded structure 33 is formed between the center terminal point 31c and the first terminal point 31a and between the center terminal point 31c and the second terminal point 31b. A gap S <b> 2 is generated between both ends in the radial direction and the inner peripheral surface 25 d of the inlet pipe 25.
For this reason, the liquid that has been prevented from flowing toward the downstream side in the EGR gas flow direction by the folding structure 33 is directed toward the downstream side in the EGR gas flow direction through the gap S2 at both radial ends of the folding structure 33. It becomes possible to flow out.
Thereby, in the swirl flow generating ribbon 30, liquid is prevented from accumulating in the gap between the first end edge 32a and the first folded piece 33a and the gap between the second end edge 32b and the second folded piece 33b. However, the liquid can be promptly guided toward the inner peripheral surface 25d of the inlet pipe 25.

And the inlet pipe 25 of this Example 1 has the 2nd area | region 25 (beta) in which the taper surface 25e which gradually enlarges an internal diameter dimension toward the downstream of the flow direction of EGR gas was formed in inner peripheral surface 25d. ing. Further, in the swirling flow generating ribbon 30, at least the first terminal point 31a and the second terminal point 31b of the terminal part 31 are inserted into the second region 25β which is a region where the tapered surface 25e is formed.
Therefore, the liquid that has flowed along the first and second end edges 32a and 32b to the first terminal point 31a and the second terminal point 31b flows out onto the tapered surface 25e. Thereby, the EGR cooler 20 of Example 1 can smoothly discharge the liquid guided to the inner peripheral surface 25d along the first and second end edges 32a and 32b toward the drain port 25c, Induction and separation can be promoted.

[Compact equipment operation]
Hereinafter, the compacting operation of the apparatus in the EGR cooler 20 of the first embodiment will be described with reference to FIG.

As shown in FIG. 2, the EGR cooler 20 according to the first embodiment includes a heat exchanging unit 21 that cools the EGR gas returned to the intake passage 2 by exchanging heat between the EGR gas and the refrigerant. In addition, the EGR cooler 20 has a swirl flow generating ribbon 30 disposed inside the inlet pipe 25 of the outflow pipe 23 connected to the end of the EGR gas outflow side of the shell 21a that is the exhaust port of the heat exchange unit 21. One end 26a of the inner pipe 26 in which the drain port 25c is formed and the exhaust port 26c is formed is inserted into the downstream side of the swirl flow generating ribbon 30. That is, the EGR cooler 20 according to the first embodiment includes a heat exchange function for cooling high-temperature EGR gas, and a gas-liquid separation function for separating gas and liquid from the EGR gas that has been cooled to become a gas-liquid two-phase fluid. ing.

Therefore, it becomes possible to perform gas-liquid separation that separates the liquid from the EGR gas that has become a gas-liquid two-phase fluid, in the outflow pipe 23 of the EGR cooler 20 that cools the EGR gas. Thereby, this EGR cooler 20 can make the piping required when providing a gas-liquid separator independently with respect to an EGR cooler unnecessary. Further, it is not necessary to secure a space for installing the gas-liquid separation device, and the size of the device can be suppressed and the size can be reduced.

Furthermore, in this EGR cooler 20, since the liquid can be separated from the EGR gas inside the outflow pipe 23, the liquid cooled to the condensed water by the heat exchange section 21 can be quickly separated from the gas and collected. Thereby, it is possible to prevent the liquid generated by condensing from the EGR gas from being re-vaporized, and to improve the removal rate of the liquid from the EGR gas.

Next, the effect will be described.
In the EGR cooler 20 of the first embodiment, the effects listed below can be obtained.

(1) A heat exchanging portion 21 for exchanging heat between the EGR gas returned from the exhaust passage 3 of the internal combustion engine 1 to the intake passage 2 and the refrigerant, and an intake port (shell) of the exhaust passage 3 and the heat exchanging portion 21 21a of the EGR gas inflow side) and the intake passage 2 and the exhaust port of the heat exchanging part 21 (the end of the EGR gas outflow side of the shell 21a). An outflow pipe 23;
The outflow pipe 23 has a swirl flow generating ribbon 30 that swirls the EGR gas along an inner peripheral surface 25d therein, and an exhaust port 26c and a drain port 25c on the downstream side of the swirl flow generating ribbon 30. Formed,
The swirl flow generating ribbon 30 is formed by a spirally twisted plate member, and is set at one end of the swirl flow generating ribbon 30 on the radially outer side at the end portion 31 facing the exhaust port 26c. The first terminal point 31a, the second terminal point 31b set at the other end of the swirling flow generating ribbon 30 on the radially outer side, and the axis O of the swirling flow generating ribbon 30, and the first terminal point 31b. A point 31a and a center end point 31c set closer to the heat exchanging part 21 than the second end point 31b, and the first end point 31a and the center end point 31c are connected to each other. One end edge 32a and a second end edge 32b connecting the second end point 31b and the center end point 31c are formed.
Thereby, the separation performance of the liquid contained in the EGR gas can be improved while suppressing an increase in the size of the apparatus.

(2) The swirling flow generating ribbon 30 is configured such that a folded structure 33 is formed on the first end edge 32a and the second end edge 32b so as to be folded toward the inflow side of the EGR gas.
Thereby, in addition to the effect of the above (1), it is difficult to separate the liquid from the first and second end edges 32a and 32b, and the liquid adhering to the swirl flow generating ribbon 30 can be prevented from being re-scattered into the gas.

(3) The folding structure 33 is formed between the center terminal point 31c and the first terminal point 31a and between the central terminal point 31c and the second terminal point 31b. The configuration.
Thereby, in addition to the effect of (2) above, the liquid is accumulated in the gap between the first end edge 32a and the first folded piece 33a and the gap between the second end edge 32b and the second folded piece 33b. While preventing, the liquid can be appropriately guided to the inner peripheral surface 25d of the inlet pipe 25.

(4) The inner peripheral surface 25d of the outflow pipe 23 is formed with a tapered surface 25e whose inner diameter dimension gradually increases along the flow direction of the EGR gas,
The swirl flow generating ribbon 30 has a configuration in which at least the first terminal point 31a and the second terminal point 31b are inserted into a region where the tapered surface 25e is formed (second region 25β).
As a result, in addition to the effects (1) to (3) above, the liquid guided to the inner peripheral surface 25d along the first and second end edges 32a and 32b is directed toward the drain port 25c. It can be discharged smoothly, and the induction and separation of liquid can be promoted.

(5) In the outflow pipe 23, the swirl flow generating ribbon 30 is disposed inside, and one end 25a is connected to an exhaust port of the heat exchanging portion 21 (an end portion on the outflow side of the EGR gas of the shell 21a). And an inlet pipe 25 in which the drain port 25c is formed, and an inner pipe 26 in which one end 26a is inserted into the other end 25b of the inlet pipe 25 and the exhaust port 26c is formed. did.
As a result, in addition to any of the effects (1) to (4) described above, it is possible to prevent the liquid adhering to the inner peripheral surface 25d of the inlet pipe 25 from entering the inner pipe 26 and to separate the gas from the liquid. Can be improved.

Although the EGR cooler of the present invention has been described based on the first embodiment, the specific configuration is not limited to this embodiment, and does not depart from the gist of the invention according to each claim of the claims. As long as the design is changed or added, it is acceptable.

In Example 1, the example which formed the folding structure 33 in the 1st end edge 32a and the 2nd end edge 32b of the terminal part 31 of the swirl | vortex flow generation | occurrence | production ribbon 30 was shown. However, the present invention is not limited to this, and the folded structure may not be formed in the terminal portion 31.
Even in this case, the extending direction of the first and second end edges 32 a and 32 b substantially coincides with the flow direction of the liquid pushed away by the swirling flow while adhering to the swirling flow generating ribbon 30. For this reason, the swirling flow generating ribbon 30 can guide the liquid toward the inner peripheral surface 25d of the inlet pipe 25 while adhering to the spiral surfaces 30a and 30b at the end portion 31.

Further, in the first embodiment, a tapered surface 25e is formed on the inner peripheral surface 25d of the inlet pipe 25, and at least the first and second swirl flow generating ribbons 30 are formed in the second region 25β where the tapered surface 25e is formed. The example which inserted the

terminal points

31a and 31b was shown. However, an inlet pipe in which the inner peripheral surface 25d is not formed with a tapered surface may be used.
Even in this case, the liquid separated from the gas-liquid two-phase fluid can flow into the drain port 25c by the swirl flow.

Further, the end portion 31 of the swirl flow generating ribbon 30 arranged in the first region 25α is extended until it is inserted into the third region 25γ of the inlet pipe 25, and this end portion 31 is close to the exhaust port 26c of the inner pipe 26. You may let them.

Further, the first and second

terminal points

31a and 31b of the swirling flow generating ribbon 30 are inserted into the second region 25β where the tapered surface 25e is formed, and the first and second end edges 32a of the swirling flow generating ribbon 30 are inserted. , 32b, both ends in the radial direction of the folded structure 33 may be extended along the inner peripheral surface 25d of the inlet pipe 25. That is, extension portions that are inserted into the third region 25γ of the inlet pipe 25 may be provided at both ends in the radial direction of the folded structure 33. The extension is formed in a V-shaped cross section by the first and second folded

pieces

33a and 33b.
At this time, in the swirling flow generating ribbon 30, the folded structure 33 is extended until the tip of the extended portion reaches the downstream position from the exhaust port 26 c of the inner pipe 26, thereby the first folded piece 33 a of the folded structure 33 and the first folded piece 33 a. The liquid flowing between the two folded pieces 33b can be guided to the inner peripheral surface 25d of the inlet pipe 25 without being scattered in the inner pipe 26.
Further, by maintaining the gap S2 generated between the extension portion of the folded structure 33 and the inner peripheral surface 25d of the inlet pipe 25, the liquid flowing along the folded structure 33 can be smoothly guided to the inner peripheral surface 25d.

Further, in the first embodiment, the start end portion 34 of the swirling flow generating ribbon 30 is erected along the direction of gravity. However, for example, the swirl flow generating ribbon 30 may be installed so that the start end portion 34 is horizontal with respect to the direction of gravity.
In this case, the liquid guided to the inner peripheral surface 25d inside the inlet pipe 25 can easily flow under the pipe under its own weight, and the liquid separated from the gas can be effectively prevented from re-scattering.

Furthermore, in the first embodiment, the shell 21a of the heat exchange unit 21 is a cylindrical hollow tube. However, the present invention is not limited to this, and the shell 21a may be a rectangular hollow tube containing stacked flat tubes. In this case, the other end 22b of the inflow pipe 22 and the one end 25a of the inlet pipe 25 of the outflow pipe 23 have a rectangular joint portion with the shell 21a. In particular, in the inlet pipe 25, the downstream side from the first region 25α where the swirl flow generating ribbon 30 is disposed needs to be cylindrical in order to turn the EGR gas into a swirl flow. Therefore, the one end 25a is formed so as to have a cylindrical shape while gradually reducing the cross-sectional area while making the portion joined to the shell 21a rectangular.

In the first embodiment, the storage tank 29 is connected to the drain pipe 27 and the liquid separated from the EGR gas that has become the gas-liquid two-phase fluid is stored, but the drain pipe 27 and the storage tank 29 are It does not necessarily have to be installed. The liquid separated in the inlet pipe 25 and discharged from the drain port 25c may not be stored.

Further, in the first embodiment, the first end edge 32 a and the second end edge 32 b are both formed in a straight line, and a space region that is notched in a V shape is generated in the terminal portion 31 of the swirling flow generating ribbon 30. However, the present invention is not limited to this. Since the center end point 31c only needs to be set on the inflow side of the gas-liquid two-phase fluid with respect to the first end point 31a and the second end point 31b, the first and second end edges 32a and 32b are curved, The end portion 31 of the swirling flow generating ribbon 30 may be cut out in a U shape.

Furthermore, the axial position of the first terminal point 31a and the axial position of the second terminal point 31b do not necessarily coincide with each other, and one of them is closer to the inflow side of the gas-liquid two-phase fluid than the other. It may be set. At this time, the end line L may not be orthogonal to the axis O of the swirl flow generating ribbon 30. And since the center terminal point 31c should just be set to the inflow side of a gas-liquid two-phase fluid rather than the 1st terminal point 31a and the 2nd terminal point 31b, it is radial from the axis O of the swirl | vortex flow generation | occurrence | production ribbon 30. It may be set at a shifted position (position near the axis O).
That is, the shape of the swirl flow generating ribbon 30 is not limited to that shown in the first embodiment. A first end point 31a, a second end point 31b set at each of the radially outer ends of the swirl flow generating ribbon 30, and a center end point 31c set at the inflow side of the gas-liquid two-phase fluid more than that, If the first and second end edges 32a and 32b, which are the ends connecting these, are provided, the setting positions of the end points and the start end points, the shapes of the end edges, and the like can be arbitrarily set.

In the first embodiment, an example in which the EGR cooler 20 is installed in a so-called lateral direction in which the flow direction of the EGR gas is horizontal with respect to the direction of gravity is shown. However, the installation direction of the EGR cooler 20 of the present invention is not limited to this, and the installation direction may be appropriately set due to the influence of the layout or the like in the exhaust gas recirculation system S.
Furthermore, in the first embodiment, the example in which the starting end portion 34 of the swirling flow generating ribbon 30 is erected along the direction of gravity is shown. However, the erected direction of the starting end portion 34 is not limited to this, and the EGR cooler 20 It is set as appropriate according to the layout.

Further, in the first embodiment, the example in which the internal combustion engine 1 is a diesel engine mounted on a vehicle is shown. However, the present invention is not limited to this, and the EGR cooler of the present invention can be applied even if the internal combustion engine 1 is a gasoline engine. Is possible.

Further, the shape of each pipe (inlet pipe 25, etc.), the shell 21a of the heat exchanging portion 21, the size of the diameter, the connection location of each member, etc. are not limited to those shown in the first embodiment, and can be arbitrarily set. .

Cross-reference of related applications

This application claims priority based on Japanese Patent Application No. 2016-243997 filed with the Japan Patent Office on December 16, 2016, the entire disclosure of which is fully incorporated herein by reference.

Claims

A heat exchanging portion that exchanges heat between the EGR gas returned from the exhaust passage of the internal combustion engine to the intake passage and the refrigerant, an inflow pipe that communicates the exhaust passage and the intake port of the heat exchanging portion, and the intake passage And an outflow pipe communicating with the exhaust port of the heat exchange section,
The outflow pipe has a swirl flow generating ribbon that swirls the EGR gas along an inner peripheral surface, and an exhaust port and a drain port are formed on the downstream side of the swirl flow generating ribbon,
The swirl flow generating ribbon is formed of a spirally twisted plate member, and has a first end point set at one end of the swirl flow generating ribbon on the radially outer side at a terminal end facing the exhaust port. A second terminal point set at the other radial outer end of the swirl flow generating ribbon, and an axis of the swirl flow generating ribbon, the first terminal point and the second terminal point being A center end point set at a position close to the heat exchange section, a first end edge connecting the first end point and the center end point, the second end point, and the center end point An EGR cooler characterized in that a second end edge is formed.
In the EGR cooler according to claim 1,
The swirling flow generating ribbon is formed with a folded structure that is folded back toward the inflow side of the EGR gas at the first end edge and the second end edge.
In the EGR cooler according to claim 2,
The EGR cooler characterized in that the folded structure is formed between the center terminal point and before the first terminal point, and between the center terminal point and before the second terminal point.
In the EGR cooler according to any one of claims 1 to 3,
On the inner peripheral surface of the outflow pipe, a tapered surface whose inner diameter dimension gradually increases along the flow direction of the EGR gas is formed.
In the EGR cooler, at least the first terminal point and the second terminal point of the swirling flow generating ribbon are inserted into a region where the tapered surface is formed.
In the EGR cooler according to any one of claims 1 to 4,
The outlet pipe has the swirl flow generating ribbon disposed therein, one end connected to the exhaust port of the heat exchanging unit, and the other end of the inlet pipe. An EGR cooler comprising: an inner pipe in which one end is inserted and an exhaust pipe is formed.