JP6201740B2 - 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 moisture from intake and exhaust.

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, diesel-equipped vehicles are equipped with a filter device that removes particulate matter in the exhaust, and the NOx trap catalyst is generally arranged downstream of the filter device from the viewpoint of heat resistance and arrangement space. Has been.

  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. In an internal combustion engine having a cooling means such as a low-pressure EGR device and an intercooler, condensation is generated by condensation when intake air including exhaust gas passes through the cooling means and is cooled. If this condensed water is sent together with the intake air from the intake passage to the combustion chamber, there is a risk of causing a water hammer.

  In order to solve the above-mentioned problems, a storage tank that stores condensed water generated in the intercooler, a heating device that heats the condensed water into steam, and water vapor that is connected to the storage tank and an exhaust passage on the upstream side of the catalyst An internal combustion engine having a supply path and supplying condensed water to steam upstream of the catalyst is disclosed in, for example, “Patent Document 1”.

JP 2013-124563 A

In the above-described technique, it is prevented that the condensed water is sent to the combustion chamber and causes water hammer, but a heating device that superheats the condensed water and changes it to steam is necessary, which increases costs and secures space. Problems arise. Therefore, it is conceivable to provide a drainage channel for discharging the generated condensed water to an exhaust pipe located upstream of the NOx trap catalyst. However, in this case, the condensed water discharged from the drainage channel flows into the NOx trap catalyst, and the catalyst is rapidly cooled by the condensed water, so that the carrier is easily cracked due to thermal stress, and the exhaust gas is deteriorated. There is.
The present invention solves the above-described problems, and provides a drainage device for an internal combustion engine in which the condensed water discharged from the drainage channel does not rapidly cool the NOx trap catalyst and can always discharge the condensed water to the exhaust pipe. Objective.

According to a first aspect of the present invention, there is provided an exhaust pipe that forms an exhaust passage of an internal combustion engine, an outer peripheral wall of the exhaust passage, a chamber that is integrally formed outside the exhaust pipe , and an intake passage of the internal combustion engine. One end is connected to the room and the other end is connected to a drainage channel for discharging condensed water in the intake passage to the room, and the room communicates with the exhaust pipe in at least two places in the exhaust direction. It is characterized by providing.

  According to a second aspect of the present invention, in the drainage device for an internal combustion engine according to the first aspect, the communication port provided further on the downstream side in the exhaust direction is in the direction of gravity than the communication port provided on the upstream side in the exhaust direction. It is arranged on the upper side.

  According to a third aspect of the present invention, in the drainage device for an internal combustion engine according to the first or second aspect, the opening at the other end of the drainage channel faces the exhaust pipe and is located upstream of the exhaust direction in the direction of gravity. It is provided between the communication port and the communication port downstream in the exhaust direction.

  According to a fourth aspect of the present invention, in the drainage device for an internal combustion engine according to any one of the first to third aspects, the internal combustion engine further includes an exhaust aftertreatment means in the exhaust passage, and the chamber is disposed after the exhaust. It is provided in the exhaust pipe on the upstream side of the processing means.

  According to a fifth aspect of the present invention, in the drainage device for an internal combustion engine according to any one of the first to fourth aspects, a fin is provided on the inner wall surface of the room.

  According to the present invention, the condensed water condensed in the intake pipe is discharged to the room provided in the exhaust passage through the drainage channel, and the high-temperature exhaust gas and the room in which the condensed water stored in the room is introduced into the room are configured. Vaporization is accelerated by the heat of the outer wall of the exhaust pipe, and the condensed water is vaporized or scattered and discharged into the exhaust passage in the form of fine particles, so that the condensed water can be taken out of the vehicle without passing through the combustion chamber of the internal combustion engine. Can be discharged.

1 is a schematic view of a drainage control device for an internal combustion engine to which an embodiment of the present invention is applied. It is the schematic of the drainage apparatus used for one Embodiment of this invention. It is the schematic explaining the operation state of the drainage device in one embodiment of the present invention.

  In FIG. 1 showing an embodiment of the present invention, a cylinder head 3 is provided on an upper portion of a cylinder block 2 of an in-vehicle diesel engine (hereinafter referred to as an engine) 1 that is an internal combustion engine. Is connected to an intake pipe 4 constituting an intake passage, and an exhaust pipe 5 constituting an exhaust passage 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, and a high-pressure EGR valve from the upstream side of the intake air. 12 etc. 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 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 the particulate matter captured by the filter device 16 is promoted by NO ₂ and is reduced by a NOx trap catalyst described later. The filter device 16 is a filter device that captures particulate matter in the 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 for detecting the amount of oxygen concentration in the exhaust gas is provided on the downstream side of the filter device 16, and as an exhaust aftertreatment means incorporating a NOx trap catalyst 18 as a catalyst on the downstream side. The catalytic converter 19 is further provided with an oxygen concentration sensor 20 downstream thereof. The NOx trap catalyst 18 is a purification device that traps NOx in an oxidizing atmosphere, releases the trapped NOx in a reducing atmosphere containing, for example, HC, CO, and the like and reduces it to N ₂ or the like. 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 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. In the middle, a low pressure EGR cooler 27 is provided. One end of the low pressure EGR pipe 26 is opened and closed by the low pressure EGR valve 8.

  Next, a drainage device 31 for an internal combustion engine used in an embodiment of the present invention that causes condensed water generated in the intake pipe 4 to flow into the exhaust pipe 5 through a drain pipe 28 that forms a drainage channel will be described. To do. Here, one end of a drain pipe 28 is connected to the intake pipe 4 between the intercooler 10 and the high pressure throttle valve 11, and the other end of the drain pipe 28 is connected to a position near the exhaust upstream side of the NOx trap catalyst 18. Has been. An opening / closing valve 29 is disposed in the middle of the drain pipe 28, and the opening / closing operation of the opening / closing valve 29 is controlled by a control means connected thereto. The control means 30 is composed of a well-known microcomputer having a CPU, ROM, RAM, etc. (not shown), and based on detection signals from various sensors, the throttle valves 7, 11, EGR valves 8, 12, and The operation of the on-off valve 29 is controlled.

The control means 30 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 of the engine 1 or the travel distance of the vehicle reaches a certain value. Further, it has a function of discharging condensed water in the drain pipe 28 through the catalytic converter 19 to the outside of the vehicle. The control means 30 detects the oxygen concentration in the intake gas leaked from the drain pipe 28 through the drain pipe 28 and the oxygen concentration sensor 20 leaks through the drain pipe 28. When this reaches a predetermined value on the lean side, the drain pipe It is determined that the condensed water has been completely removed from the valve 28, and the on-off valve 29 is closed. By the control of the control unit 30, the intake gas after condensation water discharge completion from the drainage pipe 28 by Rukoto is discharged from the drain pipe 28, occurrence of degradation and output reduction torque of the engine 1 is prevented.

  As shown in FIG. 1, a catalytic converter 19 having a NOx trap catalyst 18 is connected to the rear end of the exhaust pipe 501 upstream of the exhaust pipe 5. The catalytic converter 19 includes a container body having an enlarged diameter portion of the exhaust passage. The container body is a main portion 191 that houses the NOx trap catalyst 18, and an enlarged diameter that is an enlarged diameter portion on the front side of the exhaust passage that is continuously formed in the main portion 191. It has a front part 192 and an enlarged diameter rear part 193 on the rear side of the exhaust passage. The enlarged diameter front portion 192 forms a cone-shaped inclined portion that gradually increases the diameter of the exhaust passage toward the downstream side of the exhaust passage, and the front end thereof is connected to the upstream side exhaust pipe 501. The enlarged diameter rear portion 193 has a cone-shaped inclined portion that gradually reduces the diameter of the exhaust passage toward the downstream side of the exhaust passage, and the rear end thereof is connected to the downstream side exhaust pipe 502.

  As shown in FIG. 2, a chamber 32 for storing condensed water is provided at a site near the rear end of the upstream exhaust pipe 501. A boss 32 a is provided in the room 32, and the other end of the drain pipe 28 is connected to the upstream side so as to face the upstream exhaust pipe 501. As shown in FIG. 3, the chamber 32 is formed so that condensed water accumulates at the bottom thereof. Communication ports 33 and 34 for communication are formed. The communication port 34 formed on the downstream side in the exhaust direction from the communication port 33 is provided above the communication port 33 in the gravity g direction. A vent hole 35 may be provided at a position upstream of the communication port 33 in the exhaust direction. A fin 36 is provided inside the connection position of the drain pipe 28 in the room 32.

Next, the operation of the drainage device 31 of the 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 drain pipe 28 and is sent to the upstream exhaust pipe 501 located in the vicinity of the upstream side of the NOx trap catalyst 18, and is discharged outside the vehicle through the catalytic converter 19. Here, when the on-off valve 29 provided in the middle of the drain pipe 28 is closed, it is stored in the drain pipe 28. The on-off valve 29 is used when the amount of condensed water stored by a water level sensor (not shown) provided 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. The valve is opened by the control means 30.

  The exhaust flowing in the exhaust pipe 5 during the operation of the engine 1 flows into the catalytic converter 19 via the upstream exhaust pipe 501. When the on-off valve 29 is opened, the condensed water stored in the drain pipe 28 flows into the room 32. The condensed water that has flowed into the room 32 strikes the exhaust pipe 5 to weaken the momentum, and is stored at the bottom of the room 32. The vaporization is accelerated by the heat of the exhaust gas flowing from the communication port 33, and the vaporized vapor is discharged from the communication port 34. Here, when the vent hole 35 is provided as illustrated, the vaporized vapor is also discharged from the vent hole 35. After being scattered on the front surface of the carrier that supports the NOx trap catalyst 18, it passes through the catalytic converter 19 and is discharged outside the vehicle.

  According to the above-described configuration, since the room 32 for storing condensed water is formed integrally with the exhaust pipe 5, the condensed water stored in the room 32 is heated by the heat of the exhaust pipe 5 and vaporization is promoted. Further, since the communication ports 33 and 34 for communicating the room 32 and the exhaust pipe 5 are provided at two locations on the upstream side and the downstream side in the exhaust direction, the interior of the room 32 is directed from the communication port 33 to the communication port 34. Hot exhaust stream is introduced. Thereby, vaporization of the condensed water stored in the room 32 is further promoted by high-temperature exhaust. Note that this effect is further enhanced by the fins 36. The condensed water that has been heated or vaporized is introduced into the exhaust pipe 5 from the vent 35 or the communication port 34. In addition, a part of the condensed water in a liquid state is introduced into the exhaust pipe 5 from the communication port 34 while being promoted to be atomized by riding on the exhaust flow. As a result, the condensed water is heated and vaporized or scattered to be introduced into the catalytic converter 19 in the form of fine particles, so that occurrence of problems such as clogging of the catalytic converter 19 or cracking of the carrier of the NOx trap catalyst 18 can be reduced. it can.

  Further, when the vent hole 35 is provided, vaporized vapor passes and is discharged to the exhaust pipe 5, so that vaporization of condensed water is promoted. Further, since the vent hole 35 is provided on the upstream side of the communication port 33 in the exhaust direction, the condensed water that has flowed out even when condensed water flows out of the vent hole 35 into the exhaust pipe 5 due to vehicle vibration or the like. Since water is returned from the communication port 33 to the condensed water case 32, the occurrence of the above-described problems can be prevented. For this reason, the size of the communication port 33 is preferably larger than the size of the ventilation port 35.

  In the above-described embodiment, the configuration in which the condensed water case 32 is provided in the exhaust pipe 5 is shown, but a configuration in which the condensed water case 32 is provided in the intake pipe 4 may be adopted. When the condensed water case 32 is provided in the intake pipe 4, it is desirable that the position of the condensed water case 32 is a position immediately downstream of the intercooler 10 and the condensed water generated in the intercooler 10 is immediately received. Further, assuming that the condensed water overflows from the condensed water case 32, one end of the drain pipe 28 may be connected to a position downstream of the condensed water case 32 in the intake direction.

1 Internal combustion engine
4 Intake passage (intake pipe)
5 Exhaust passage (exhaust pipe)
19 Exhaust aftertreatment means (catalytic converter)
28 Drainage channel (drainage pipe)
31 Drainage device 32 Room 33, 34 Communication port 35 Vent port 36 Fin

Claims (5)

An exhaust pipe forming an exhaust passage of the internal combustion engine;
A chamber that includes an outer peripheral wall of the exhaust passage and is integrally formed outside the exhaust pipe ;
One end is connected to the intake passage of the internal combustion engine, the other end is connected to the room, respectively, and a drainage channel for discharging condensed water in the intake passage to the room,
The drainage device for an internal combustion engine, wherein the chamber includes a communication port communicating with the exhaust pipe at at least two places in an exhaust direction. In the internal combustion engine drainage device according to claim 1,
The drainage device for an internal combustion engine, wherein the communication port provided on the downstream side in the exhaust direction is disposed on the upper side in the gravity direction than the communication port provided on the upstream side in the exhaust direction. The internal combustion engine drainage device according to claim 1 or 2,
An opening at the other end of the drainage channel is opposed to the exhaust pipe, and is provided between the communication port on the upstream side in the exhaust direction and the communication port on the downstream side in the exhaust direction in the direction of gravity. Engine drainage device. The internal combustion engine drainage device according to any one of claims 1 to 3,
The internal combustion engine is provided with exhaust aftertreatment means in the exhaust passage, and the chamber is provided in the exhaust pipe upstream of the exhaust aftertreatment means. In the internal combustion engine drainage device according to any one of claims 1 to 4,
A drainage device for an internal combustion engine, wherein fins are provided on an inner wall surface of the room.

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