JP6201738B2 - Drainage device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine of a vehicle, and more particularly to a drainage device that drains condensed water generated in an intake and exhaust system.

As an exhaust gas purification method for a diesel engine, a method using a NOx trap catalyst is known. The NOx trap catalyst captures NOx in exhaust gas in an oxidizing atmosphere, releases the trapped NOx in a reducing atmosphere, and reduces it to N ₂ or the like, thereby reducing the NOx emission concentration. In addition, a diesel engine-equipped vehicle is provided with a filter device that removes particulate matter (PM) in the exhaust. The NOx trap catalyst is generally downstream of the filter device from the viewpoint of heat resistance and arrangement space. Arranged on the side.

  Furthermore, an exhaust gas recirculation (EGR) system is known in which part of the exhaust gas is returned to the intake side to lower the combustion temperature of the combustion chamber and reduce NOx in the exhaust gas. The EGR system includes a high-pressure EGR system for returning exhaust gas from the turbine upstream exhaust passage of the turbocharger to the compressor downstream intake passage, and an oxidation catalyst and filter device downstream exhaust passage downstream from the turbine to the compressor upstream intake passage. There is a low pressure EGR system that returns exhaust gas. Here, in an internal combustion engine provided with cooling means such as a low-pressure EGR device and an intercooler, condensation is generated when the intake air including exhaust gas passes through the cooling means and is cooled. When this condensed water is sent from the intake passage to the combustion chamber together with the intake air, a water hammer may be caused.

  Therefore, as disclosed in “Patent Document 1”, a storage tank in which the drainage device of the internal combustion engine stores condensed water generated in the intercooler, a heating device that heats the condensed water to form water vapor, a storage tank, It is assumed that a configuration having a water vapor supply path connected to an exhaust passage on the upstream side of the catalyst is adopted. In this case, the condensed water is changed to water vapor and supplied to the upstream exhaust passage of the catalyst.

  In the above technology, condensate is prevented from being sent to the combustion chamber and causing water hammer, but a heating device that heats the condensate and turns it into water vapor is necessary, which increases costs and secures space. Etc. are likely to occur. Therefore, it is conceivable to adopt a configuration in which a condensed water discharge passage is installed in order to discharge the condensed water generated in the intercooler to the upstream exhaust pipe of the NOx trap catalyst. However, in this case, sufficient boost pressure cannot be obtained in the low load region of the engine, so that the condensed water flows backward to the intake passage side when the condensed water discharge passage is opened, and cannot be discharged to the exhaust passage. Problem is likely to occur.

JP 2013-180757 A

  Therefore, in order to reliably discharge the condensed water to the exhaust passage without causing the condensed water to flow back to the intake passage side, it is desired to adopt a configuration that generates a negative pressure at the outlet of the condensed water discharge passage. .

  The present invention solves the above-mentioned problems, and the object of the present invention is to be able to easily drain the condensed water of the intake / exhaust system using a drainage channel configuration utilizing the venturi effect while suppressing an increase in cost. It is providing the drainage device of the internal combustion engine.

According to the first aspect of the present invention, one end is connected to the enlarged diameter portion of the exhaust passage of the internal combustion engine, and the other end is connected to an exhaust passage having a smaller pipe diameter upstream than the exhaust passage to which the one end is connected. A bypass,
One end in the exhaust passage upstream of the connecting position of the intake passage or the bypass passage of the internal combustion engine, the condensed water and the other end is condensed by each of the intake passage is connected or the exhaust passage to the bypass passage And a drainage channel that discharges to the bypass channel.

According to a second aspect of the present invention, in the drainage device for an internal combustion engine according to the first aspect, the bypass passage is formed with a throttle for reducing the pipe diameter from the one end toward the other end, and the other end of the drainage passage is connected to the downstream side bypass path of said aperture, characterized in that.

According to a third aspect of the invention, in the drainage device for an internal combustion engine according to the first or second aspect, the exhaust device is disposed on the exhaust passage, and the exhaust pipes on the upstream side and the downstream side of the exhaust passage are provided with an enlarged diameter portion. in an internal combustion engine provided with a connected exhaust aftertreatment device, the one end of the bypass passage is connected to the enlarged diameter portion, the other end of the bypass passage is connected to the upstream side of the exhaust pipe of the enlarged diameter portion It is characterized by that.

  According to a fourth aspect of the present invention, in the internal combustion engine drainage device according to any one of the first to third aspects, the intercooler is disposed in the intake passage, and one end of the drainage channel is the intercooler. It is connected to the intake passage on the downstream side of the cooler.

According to the first aspect of the present invention, it is possible to suppress an increase in cost and reliably discharge the condensed water generated in the intake passage or the exhaust passage by the drainage channel to the exhaust pipe downstream side. That is, one end of the bypass passage is connected to the exhaust passage, and the other end is connected to the exhaust passage having a smaller diameter than the exhaust passage to which the one end is connected. A flow toward the other end occurs. By connecting the downstream end of the drainage channel to this bypass channel, negative pressure is generated in the drainage channel along with the flow in the bypass channel, and the condensed water in the drainage channel is quickly discharged to the bypass channel. be able to. Further, condensed water can flow quickly to the exhaust passage downstream without staying in order to be promoted in advance exhausted and stirred atomized by bypass passage, the exhaust passage when it is discharged into the exhaust passage .

A second aspect of the present invention, by forming the diaphragm along the exhaust gas flow of the bypass passage, thereby improving the speed of the exhaust gas flow by further squeezing. By connecting the downstream end of the drainage channel to the downstream side of the throttle, the negative pressure in the drainage channel is accelerated by the venturi effect of the throttle and further increased by the exhaust flow. Therefore, it is possible to facilitate the discharge of water from the intake passage to the exhaust passage.

The invention of claim 3 is connected to the enlarged diameter portion to which one end of the bypass passage connects the exhaust pipe and the exhaust aftertreatment unit, at the other end is connected to the exhaust pipe upstream of the expanded diameter portion, exhaust flow by the venturi effect in the bypass passage without forming a new enlarged diameter portion in the exhaust passage can be made. Further, condensed water to be discharged to the upstream side of the exhaust passage of the exhaust aftertreatment unit via the bypass passage can be contained condensate exhaust gas is purified by the exhaust aftertreatment unit.

  Since the condensed water condensed by the intercooler flows into the exhaust passage through the drainage passage and the bypass passage, corrosion of the intake passage can be suppressed and the engine can be prevented from causing water hammer.

1 is an overall configuration diagram of an intake / exhaust system of a vehicle-mounted diesel engine equipped with a drainage device for an internal combustion engine according to an embodiment of the present invention. 1 shows a catalytic converter used in the drainage device of the internal combustion engine of FIG. 1, (a) is an enlarged partial cutaway sectional view of a front bypass path, and (b) is an enlarged main part on the other end side of the bypass path in (a). It is sectional drawing.

A drainage device for an internal combustion engine to which the present invention is applied will be described with reference to the following drawings.
In short, the present invention is characterized by a drainage dispersion configuration that can prevent the catalytic device from being damaged when draining the condensed water generated in the intake passage to the upstream side of the catalytic device in the exhaust passage.
Here, the case where the drainage device for an internal combustion engine of the present invention is applied to an air supply / exhaust system of a vehicle-mounted diesel engine will be described as a first embodiment.

  A vehicle-mounted diesel engine (hereinafter referred to as an engine) 1 on which a drainage device for an internal combustion engine according to the first embodiment is mounted includes a cylinder block 2 that forms a central portion of a main body, and a cylinder head 3 is provided on the cylinder block 2. An intake pipe 4 constituting an intake passage IR is connected to the intake side of the cylinder head 3 and an exhaust pipe 5 constituting an exhaust passage ER is connected to the exhaust side. A fuel injection pump 14 is connected to the cylinder head 3 via a common rail 13. Further, the cylinder head 3 is connected to the other end of a blow-by gas passage 21 for discharging blow-by gas having one end connected to the intake pipe 4 on the downstream side of the air filter 6.

The intake pipe 4 includes an air filter 6, a low pressure throttle valve 7, a low pressure EGR valve 8, a turbocharger 9 (not shown), an intercooler 10, a high pressure throttle valve 11, a high pressure from the upstream side of the intake passage IR. An EGR valve 12 and the like are provided.
The exhaust pipe 5 is provided with a turbine (not shown) of the turbocharger 9, an oxidation catalyst 15, and a filter device 16 as an exhaust filter from the upstream side of the exhaust passage on the cylinder block 2 side.

The oxidation catalyst 15 carries a noble metal catalyst such as platinum, and has an action of converting NO in the exhaust into NO ₂ and an action of oxidizing harmful components such as HC and CO in the exhaust. Yes. NO ₂ has a stronger oxidizing action than NO, and the oxidation reaction of particulate matter (diesel particulates) captured by the filter device 16 by NO ₂ is promoted. The NO ₂ is reduced and removed by a NOx trap catalyst 18 described later. The filter device 16 is a filter device (diesel particulate filter) that captures particulate matter in exhaust gas, and the captured particulate matter is burned and removed by the strong oxidizing action of NO ₂ .

An oxygen concentration sensor (LAFS) 17 that detects the amount of oxygen concentration in the exhaust gas is provided on the downstream side of the filter device 16, and a catalytic converter 19 that incorporates a NOx trap catalyst 18 that is a catalyst on the downstream side thereof, Further, an oxygen concentration sensor 20 is provided on the downstream side. The NOx trap catalyst 18 as exhaust aftertreatment means disposed on the exhaust passage ER captures NOx in an oxidizing atmosphere, releases the trapped NOx in a reducing atmosphere containing, for example, HC, CO, and the like (N ₂ ) Is a purifying device having a function of reducing to. That is, NO ₂ generated by the oxidation catalyst 15 and NO remaining in the exhaust gas without being oxidized by the oxidation catalyst 15 are captured, reduced to nitrogen (N ₂ ), and released.

  A high pressure EGR device 22 having a high pressure EGR pipe 23 and a high pressure EGR cooler 24 is disposed below the high pressure EGR valve 12. One end of the high-pressure EGR pipe 23 is connected to the intake pipe 4 between the high-pressure throttle valve 11 and the cylinder head 3, and the other end is connected to the exhaust pipe 5 between the cylinder head 3 and the turbine of the turbocharger 9. A high-pressure EGR cooler 24 is provided in the middle. One end of the high pressure EGR pipe 23 is opened and closed by the high pressure EGR valve 12.

  Below the low pressure EGR valve 8, a low pressure EGR device 25 is disposed as an exhaust gas recirculation device having a low pressure EGR pipe 26 and a low pressure EGR cooler 27. One end of the low-pressure EGR pipe 26 is connected to the intake pipe 4 between the low-pressure throttle valve 7 and the compressor of the turbocharger 9, and the other end is connected to the exhaust pipe 5 between the filter device 16 and the NOx trap catalyst 18. A low pressure EGR cooler 27 is provided in the middle. One end of the low pressure EGR pipe 26 is opened and closed by the low pressure EGR valve 8.

Next, a drainage device M1 for an internal combustion engine according to Embodiment 1 of the present invention that causes condensed water generated in the intake passage IR to flow into the exhaust passage ER through the drainage passage wr will be described.
The drain pipe 28 forming the drain channel wr here has an inlet 281 at one end thereof downstream of the intercooler and connected to the intake pipe 4 between the intercooler 10 and the high-pressure throttle valve 11, and is an exhaust aftertreatment means. A drain port 282 at the other end is connected to the upstream side of the exhaust passage of a certain NOx trap catalyst 18. The configuration of the drain pipe 28 and its connecting portion will be described later.
An on-off valve 29 is provided in the middle of the drain pipe 28, and a control means 31 that controls opening / closing of the on-off valve is connected to the on-off valve 29.

  As described above, the control means 31 opens the on-off valve 29 when the amount of condensed water stored in the drain pipe 28 reaches a certain amount, or when the operation time or travel distance of the engine 1 reaches a certain value. And has a function of discharging the condensed water in the drain pipe 28 through the catalytic converter 19 to the outside of the vehicle. Further, the control means 31 detects the oxygen concentration in the intake gas leaked from the drain pipe 28 and the oxygen concentration sensor 20 leaks through the drain pipe 28, and when this reaches a predetermined value on the lean side, the drain pipe 28. Therefore, it is determined that the condensed water has been completely removed from the valve, and the on-off valve 29 is closed. Control of the control means 31 prevents intake gas from being discharged from the drain pipe after completion of drain of condensed water from the drain pipe 28, thereby causing a reduction in torque and a reduction in output of the engine 1.

  Next, as shown in FIG. 1, a catalytic converter 19 having a NOx trap catalyst (exhaust aftertreatment means) 18 is connected to the rear end of the upstream side exhaust pipe 501 forming the exhaust passage ER. The catalytic converter 19 includes a cylindrical container body (shell) that forms an enlarged diameter portion of the exhaust passage ER. The container main body includes a main portion 191 that houses and holds the NOx trap catalyst 18, a diameter expansion front portion 192 that is a diameter expansion portion on the front side of the exhaust passage ER continuously formed in the main portion 191, and a diameter expansion rear portion on the rear side of the exhaust passage ER. 193.

The enlarged diameter front portion 192 forms a cone-shaped inclined portion (front cone) that gradually increases the diameter of the exhaust passage toward the downstream of the exhaust passage, and its front end is connected to the upstream exhaust pipe 501 upstream of the exhaust passage. The enlarged diameter rear portion 193 forms a cone-shaped inclined portion that gradually reduces the exhaust passage diameter toward the downstream, and the rear end thereof is connected to the downstream exhaust pipe 502 on the downstream side of the exhaust passage.
As shown in FIG. 2A, the rear end portion of the upstream side exhaust pipe 501 overlaps the front end of the enlarged diameter front portion 192 and has a relatively small exhaust passage cross section a1 up to a position where they are welded to each other. Then, the exhaust passage cross section a2 gradually increases as it moves backward in the exhaust passage direction X, and the NOx trap catalyst 18 is accommodated and held at the main portion 191 with a maximum value.

  The rear end portion of the upstream exhaust pipe 501 immediately before reaching the container main body (shell) forming such a diameter-expanded portion has a large exhaust gas flow velocity v1 and a small gas pressure Pa1. In the enlarged diameter front part 192, the exhaust gas flow velocity v2 decreases as it advances rearward, and the gas pressure Pa2 increases accordingly. Further, in the vicinity of the front end of the main portion 191, the exhaust gas flow velocity v3 becomes smaller, and the gas pressure Pa3 further increases accordingly. Moreover, in the vicinity of the front end of the main portion 191, the speed of the NOx trap catalyst 18 in the diameter increasing direction along the front surface f1 of the carrier increases, and the exhaust gas is dispersed over the entire front surface f1 of the carrier and the exhaust gas reaches the carrier of the NOx trap catalyst 18. It flows in and flows out in the exhaust path direction X.

A bypass pipe 32 forming a bypass passage br as shown in FIGS. 1 and 2 is connected between the catalytic converter 19 in which such a flow of exhaust gas is formed and the upstream exhaust pipe 501.
Here, one end of the bypass pipe 32 is connected to the enlarged diameter front part 192 which is an enlarged diameter part on the front side of the exhaust passage ER, and the other end is located upstream of the position on the exhaust passage ER to which one end is connected. It is connected to the upstream exhaust pipe 501 having a small diameter.
As shown in FIG. 2A, one end of the bypass pipe 32 is connected by fastening a flare nut 35 to one end-side boss 33 welded to the front end of the main portion 191 immediately adjacent to the enlarged diameter front portion 192. A through hole 331 is formed in the one end boss 33, and the one end side communication port 36 at the lower end of the through hole 331 communicates with the inner chamber in the vicinity of the front end of the main portion 191.

The other end of the bypass pipe 32 is connected to the other end boss 34 welded to the upstream exhaust pipe 501 having a smaller pipe diameter on the upstream side than the position on the one end side on the exhaust passage ER. By fastening the flare nut 35 to the other end boss 34, the other end of the bypass pipe 32 is fastened to the other end boss 34.
2A and 2B, the other end boss 34 has a through hole 341 formed in the center, and the other end communication port 37 at the lower end of the through hole 341 is an exhaust path of the upstream exhaust pipe 501. It communicates with the vicinity of the rear end of ER.

As shown in FIG. 2B, the end boss 34 has a central through hole 341 whose diameter is lower at the lower part h2 than at the upper part h1, and a diaphragm 342 is formed at the stepped part. An outflow hole 343 is formed at the upper end of the lower part h2 below the throttle 342. The outflow hole 343 is fastened to the other end boss 34 by a flare nut 35, and a drain outlet 282 on the lower end side of the drain pipe 28 is connected. Is done.
Here, since the exhaust gas flows from the throttle 342 to the lower part h2 side, the throttle 342 is formed along the exhaust flow ef flowing through the bypass pipe 32, so that the speed of the exhaust flow ef by the throttle 342 increases. A negative pressure increase region eh is generated in the lower part h2 on the downstream side of the throttle 342. By connecting the downstream end of the drainage channel wr here, the flow in the drainage channel wr becomes the venturi effect of the throttle 342. Is increased to a larger flow fr and merges.

The operation of the drainage device M of such an internal combustion engine will be described.
During operation of the engine 1, particularly when the low-pressure EGR device 25 is used, a large amount of condensed water is generated at the outlet of the intercooler 10. The generated condensed water passes through the drainage wr and is sent into the upstream exhaust pipe 501 through the bypass pipe 32 located in the vicinity of the upstream side of the NOx trap catalyst 18.
Here, the exhaust gas flows from the upstream side exhaust pipe 501 to the NOx trap catalyst 18 through the enlarged diameter front portion 192 and the main portion 191. At this time, as shown in FIG. 2A, since the gas pressure Pa3 of the main portion 191 is large and the gas pressure Pa1 of the rear end portion of the upstream side exhaust pipe 501 is small, the exhaust gas depends on the differential pressure. Passes through the bypass pipe 32 from the one end side communication port 36 as an exhaust flow ef and flows to the other end side communication port 37.

In this manner, one end of the bypass pipe 32 is connected to the catalytic converter 19 which is a diameter-expanded part that connects the NOx trap catalyst 18 (exhaust aftertreatment means) and the upstream side exhaust pipe 501, and the other end is upstream from the diameter-expanded part. Side upstream exhaust pipe 501. For this reason, it is possible to create the exhaust flow ef due to the venturi effect in the bypass passage without forming a new enlarged portion in the exhaust passage ER. In this respect, it is possible to suppress an increase in cost.
Further, since the condensed water is discharged to the upstream exhaust pipe 501 on the upstream side of the NOx trap catalyst 18 via the bypass passage, the exhaust gas containing the condensed water is purified by the NOx trap catalyst 18 (exhaust aftertreatment means). I can do it.

  Further, the speed of the exhaust flow ef is increased by the throttle 342de, a low pressure region eh is generated in the lower portion h2 immediately below the exhaust flow ef, and the negative pressure in the drainage channel wr is accelerated by the venturi effect of the throttle 342. For this reason, the ratio that the condensed water in the drainage channel wr is vaporized and flows into the exhaust flow ef in the lower portion h2 is increased, the speed is further increased, and the condensed water is discharged to the upstream exhaust pipe 501 from the other end side communication port 37. . Accordingly, it is possible to facilitate the discharge of water from the intake passage IR to the exhaust passage ER and to the exhaust passage, so that the exhaust gas containing condensed water can be purified by the exhaust post-processing means.

  Furthermore, since the condensed water condensed in the intercooler 10 flows into the exhaust passage ER through the drain passage wr and the bypass passage br, corrosion of the intake passage IR can be suppressed, and the engine 1 can be prevented from causing water hammer.

In the above description, the drainage wr in the drainage device for the internal combustion engine according to the first embodiment has led the condensed water condensed by the intercooler 10 to the bypass br and flowed into the exhaust passage ER. As shown by a two-dot chain line, another embodiment in which the inlet 281a at one end of the drain pipe 28a forming the drain wr is communicated with the exhaust path ER in the exhaust pipe 5 ′ upstream of the engine body may be configured. .
In this case, when the engine 1 is in an idle state, condensed water may be generated in the exhaust pipe 510 downstream of the combustion chamber. It is preferable to eliminate the condensed water in terms of ensuring durability, and the exhaust gas recirculation device. Inflow of condensed water to the (low pressure EGR device) 25 can be prevented.

  In the above description, the drainage device of the internal combustion engine is mounted on the on-board diesel engine. However, it may be mounted on a stationary diesel engine depending on the case, and may be further mounted on a gasoline engine. Almost the same effect can be obtained.

1 Internal combustion engine
4 Intake pipe 5 Exhaust pipe 501 Upstream exhaust pipe 10 Intercooler 18 NOx trap catalyst (exhaust aftertreatment means)
19 Catalytic converter (expanded part)
191 Main part 192 Diameter expansion front part 25 Exhaust gas recirculation device (low pressure EGR device)
28 Drain pipe 31 Control means 32 Bypass pipe 33 One end side boss 331 Through hole 34 Other end side boss 341 Through hole 36 One end side communication port 37 Other end side communication port br Bypass path wr Drainage path IR Intake path ER Exhaust path M Internal combustion engine Drainage device X Exhaust direction

Claims (4)

A bypass path having one end connected to an enlarged diameter portion of the exhaust passage of the internal combustion engine and the other end connected to an exhaust passage having a smaller pipe diameter upstream of the exhaust path to which the one end is connected;
One end in the exhaust passage upstream of the connecting position of the intake passage or the bypass passage of the internal combustion engine, the condensed water and the other end is condensed by each of the intake passage is connected or the exhaust passage to the bypass passage A drainage device for an internal combustion engine, comprising: a drainage channel that discharges to the bypass channel. The bypass passage is formed aperture to reduce the pipe diameter toward the other end from the one end, the other end of the drain passage is connected to the bypass passage downstream of the throttle above,
2. The drainage device for an internal combustion engine according to claim 1. An internal combustion engine comprising exhaust aftertreatment means disposed on the exhaust passage and connected to exhaust pipes on the upstream side and downstream side of the exhaust passage via an enlarged diameter portion,
One end of the bypass passage is connected to the enlarged diameter portion, the other end of the bypass passage is connected to the upstream side of the exhaust pipe of the enlarged diameter portion,
The drainage device for an internal combustion engine according to claim 1 or 2, characterized in that An intercooler disposed in the intake passage, and one end of the drainage channel is connected to the intake passage on the downstream side of the intercooler,
The drainage device for an internal combustion engine according to claim 1, wherein the drainage device is an internal combustion engine.

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