JP2019044758A - Exhaust emission control device - Google Patents

Abstract

To provide an exhaust emission control device capable of suppressing influence on the pressure loss.SOLUTION: An exhaust emission control device includes a filter which collects particulate matter in exhaust gas from an internal combustion engine and is regenerated by combustion of the collected particulate matter, a tank for storing condensate water, and a transferring section for transferring the condensate water to the exhaust upstream side of the filter so as to carry away ash accumulated on the filter by regeneration toward the exhaust downstream side of the filter with the condensate water. For example, the condensate water is the condensate water generated by an exhaust system of the internal combustion engine.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an exhaust purification device.

  2. Description of the Related Art Conventionally, for example, a diesel particulate filter (Diesel Particulate Filter: DPF) is known as a filter that collects particulate matter (hereinafter referred to as PM) contained in exhaust gas from an internal combustion engine.

  PM contains trace amounts of metal components contained in oil and fuel additives. The PM collected in the DPF is burned and removed by regeneration, but the metal component is generated on the DPF as an unburned component. The unburned component may be called ash.

  Ashes are classified as wall ash that accumulates on the DPF, and plug ash that accumulates on the exhaust downstream side of the DPF.

JP 2011-202573 A

  By the way, it is known that the effect of the ash deposition on the pressure loss of the DPF is larger in the wall ash than in the plug ash.

  The fundamental method for removing the deposited ash is regular cleaning, and no other fundamental method is found. For this reason, it is difficult to find a method for suppressing the influence on pressure loss other than cleaning at the time of inspection.

  An object of the present disclosure is to provide an exhaust emission control device that can suppress an effect on pressure loss.

An exhaust emission control device of the present disclosure includes:
A filter that collects particulate matter in exhaust gas from an internal combustion engine and is regenerated by burning the collected particulate matter;
A tank for storing condensed water;
A transfer unit for transferring the condensed water to the exhaust upstream side of the filter so that the ash deposited on the filter by the regeneration is pushed to the exhaust downstream side of the filter by the condensed water;
Is provided.

An internal combustion engine of the present disclosure includes
The above exhaust purification device is provided.

  According to the present disclosure, the influence on the pressure loss can be suppressed.

Schematic configuration diagram partially showing an example of an exhaust system of an engine according to an embodiment of the present disclosure Partial longitudinal sectional view of the DPF before the condensed water flows along the exhaust direction Partial longitudinal sectional view of the DPF after the condensed water circulates cut along the exhaust direction Flow chart showing an example of the condensate distribution process

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
In the present embodiment, a case where the present invention is applied to a diesel engine (internal combustion engine) mounted on an automobile will be described.

  First, a schematic structure of a diesel engine (hereinafter simply referred to as an engine) according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating an example of an exhaust system of an engine according to an embodiment. 1 to 3, the X axis is drawn. In the following description, the left-right direction in FIGS. 1 to 3 is referred to as the X direction or the exhaust direction, the right direction is “+ X direction”, “exhaust downstream direction” or “exhaust downstream side”, and the left direction is “−X direction”. , “Exhaust upstream direction” or “exhaust upstream side”.

  As shown in FIG. 1, an exhaust pipe 10 is connected to an exhaust manifold (not shown) of the engine. Exhaust gas from the engine flows into the exhaust pipe 10. An oxidation catalyst (Diesel Oxidation Catalyst: DOC) 11 and a DPF 12 are provided in the exhaust pipe 10 in order from the exhaust upstream side (−X direction).

  When the fuel is supplied, the DOC 11 oxidizes the fuel and raises the temperature of the exhaust gas.

  2 and 3 are partial longitudinal sectional views of the DPF 12 cut along the exhaust direction (X direction).

  The DPF 12 has a large number of cells 121 partitioned by a porous partition wall 122. The cells 121 are arranged along the exhaust direction (X direction). The inlet of the cell 121 on the exhaust upstream side (−X direction) and the outlet on the exhaust downstream side (+ X direction) are alternately plugged. The DPF 12 collects PM contained in the exhaust gas in the pores and the surface of the partition wall 122. The DPF 12 is regenerated by burning the PM collected in the partition wall 122 of the DPF 12. The regeneration of the DPF 12 is performed by supplying fuel to the DOC 11 on the exhaust upstream side of the DPF 12 and raising the temperature of the exhaust gas to the PM combustion temperature.

  In PM discharged from the engine, there is an unburned component called ash generated from a metal component contained in oil or a fuel additive (hereinafter referred to as oil or the like). Ashes remain in the DPF 12 and occupy the volume of the DPF 12. Thereby, since the area which filters PM in DPF12 decreases, a pressure loss rises with a travel distance.

  The effect of ash deposition on pressure loss depends on where in the DPF 12 the ash is deposited. FIG. 2 shows the wall ash 3 a deposited on the partition wall 122 of the DPF 12. FIG. 3 shows the plug ash 3b deposited on the exhaust downstream side of the DPF 12 (cell outlet side).

  It is known that the effect of ash deposition on pressure loss is greater in the wall ash 3a than in the plug ash 3b.

  As shown in FIG. 1, the exhaust purification apparatus 1 according to the present embodiment includes a tank 20 and a transfer unit 30 in addition to the DPF 12 described above.

  The tank 20 stores the condensed water 2.

  The condensed water 2 is, for example, condensed water generated in an engine exhaust system. Specifically, the exhaust gas discharged from the engine includes water vapor that is originally included in the intake air, as well as water vapor generated as a result of fuel or PM combustion. The temperature of the exhaust gas containing water vapor is lowered while flowing through the exhaust system, and when the temperature of the exhaust gas falls below the dew point, the water vapor is condensed and condensed water is generated in the exhaust gas. The generated condensed water is stored in the tank 20.

  Further, the condensed water 2 is, for example, condensed water in the EGR gas. Specifically, when the EGR gas cooled by the EGR cooler is cooled below the dew point, moisture in the EGR gas is condensed and condensed water is generated. The generated condensed water is stored in the tank 20.

  As shown in FIG. 1, the transfer unit 30 includes a pump 31, a nozzle 32, a water channel 33, and a control valve 34.

  The pump 31 is connected to the tank 20 by a water channel 33. The pump 31 transfers the condensed water 2 in the tank 20 to the nozzle 32 via the water channel 33.

  The nozzle 32 is disposed on the exhaust upstream side (−X direction) of the DPF 12. The nozzle 32 discharges the condensed water 2 toward the exhaust upstream side (cell inlet side) of the DPF 12. The condensed water 2 flows from the exhaust upstream side (−X direction) of the DPF 12 to the exhaust downstream side (+ X direction). The flow direction of the condensed water 2 is indicated by white arrows in FIG.

  The transfer unit 30 transfers the condensed water 2 having higher viscosity than the exhaust gas to the exhaust upstream side of the DPF 12. The transferred condensed water circulates in the DPF 12 to push the wall ash 3a deposited on the partition wall 122 of the cell 121 to the exhaust downstream side (+ X direction). FIG. 2 shows the direction in which the wall ash 3a is swept away by arrows.

  The form of the wall ash 3a is deformed into the form of the plug ash 3b by the wall ash 3a being pushed away to the exhaust downstream side by the condensed water 2 (see FIG. 3). Further, the amount of wall ash 3 a deposited on the partition wall 122 decreases as the ash component dissolves in the condensed water 2 and flows out of the cell 121 together with the condensed water 2.

  The control valve 34 starts the transfer of the condensed water 2 to the nozzle 32 by opening the water channel 33, and stops the transfer of the condensed water 2 to the nozzle 32 by closing the water channel 33.

  The ECU 40 controls the control valve 34 so as to open the water channel 33 to discharge the condensed water 2 from the nozzle 32 when a certain condition is satisfied, and to close the water channel 33 otherwise. Specifically, the ECU 40 opens the water channel 33 when the engine is cold started. Release of the condensed water 2 is performed based on the oil consumption, the amount of condensed water, and the like. A specific method for discharging the condensed water 2 (for example, the amount of water, time, etc.) is set based on simulations or experimental results.

  Next, the circulation process of the condensed water will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the condensate distribution process. This process is started by starting the engine.

  In step S100, the ECU 40 determines whether or not it is during a cold start of the engine. If it is during the cold start of the engine (step S100: YES), the ECU 40 controls the pump 31 and the control valve 34 so as to transfer the condensed water to the exhaust upstream side of the DPF 12 (step S110). The process returns to step S100 after a predetermined time.

  If the engine is not cold started (step S100: NO), the process ends.

<Effects of the present embodiment>
As described above, the exhaust purification apparatus 1 according to the present embodiment collects PM in exhaust gas from the engine, and uses the DPF 12 regenerated by burning the collected PM and condensed water. A tank 20 to be stored, and a transfer unit 30 that transfers the condensed water to the exhaust upstream side of the DPF 12 so that the ash deposited on the DPF 12 by regeneration is pushed to the exhaust downstream side of the DPF 12 by the condensed water. By causing the wall ash 3a to be washed away to the exhaust downstream side, a change in form from the wall ash 3a to the plug ash 3b can be promoted. As a result, the influence of the wall ash 3a on the pressure loss can be suppressed.

  Moreover, according to the exhaust gas purification apparatus 1 according to the present embodiment, the transfer unit 30 transfers the condensed water 2 to the DPF 12 when the engine is cold started. As a result, even when the amount of PM contained in the exhaust gas is large during cold start and a large amount of wall ash 3a is deposited on the DPF 12 accordingly, the condensate 2 is transferred to the DPF 12 to Since the form of the ash 3a can be changed to the form of the plug ash 3b, the influence of pressure loss can be suppressed.

  In the exhaust gas purification apparatus 1, the condition for transferring the condensed water to the DPF 12 is the cold start of the engine, but the present invention is not limited to this. What is necessary is just the temperature which the condensed water distribute | circulated through DPF12 does not evaporate. Further, for example, the pressure difference (differential pressure) between the pressure upstream of the DPF 12 and the downstream side of the exhaust may exceed a predetermined value. Further, for example, the engine may be cold started and the differential pressure may exceed a predetermined value.

  The exhaust purification device of the present disclosure is useful as an internal combustion engine that is required to suppress the effect on pressure loss.

DESCRIPTION OF SYMBOLS 1 Exhaust purification device 2 Condensed water 10 Exhaust pipe 11 DOC
12 DPF
20 tank 30 transfer part 31 pump 32 nozzle 33 water channel 34 control valve 40 ECU

Claims (5)

A filter that collects particulate matter in exhaust gas from an internal combustion engine and is regenerated by burning the collected particulate matter;
A tank for storing condensed water;
A transfer unit for transferring the condensed water to the exhaust upstream side of the filter so that the ash deposited on the filter by the regeneration is pushed to the exhaust downstream side of the filter by the condensed water;
An exhaust emission control device.   The exhaust purification device according to claim 1, wherein the condensed water is condensed water generated in an exhaust system of the internal combustion engine.   The exhaust gas purification apparatus according to claim 1, wherein the condensed water is a condensed water of EGR gas.   The exhaust purification device according to any one of claims 1 to 3, wherein the transfer unit transfers the condensed water when the internal combustion engine is cold-started.   An internal combustion engine comprising the exhaust emission control device according to any one of claims 1 to 4.

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