JP2002195023A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge an operation region in which a ventilating type purification member has an activity, by increasing, without having to use forcible heating means such as an electric heater and a burner, the temperature of an exhaust gas introduced in the ventilating type purification member, such as a catalyst regeneration type particulate filter. SOLUTION: In this exhaust emission control device, the catalyst regeneration type particulate filter 11 (ventilating type purification member), through which the exhaust gas 8 is made to pass to carry out purification, is provided in a halfway of an exhaust pipe 10. A heat radiation part 13 is arranged immediately in front of the particulate filter 11, a heat-absorbing part 14 is arranged at an upstream part of the heat radiating part 13 having relatively high exhaust temperature, and the heat-absorbing part 14 and the heat radiation part 13 are connected to each other via a heat pipe 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust emission control device.

[0002]

2. Description of the Related Art Particulate matter (particulate matter) emitted from a diesel engine is:
Soot composed of carbonaceous material and SO composed of high-boiling hydrocarbon component
F (Soluble Organic Fraction: Soluble Organic Component) and a small amount of sulfate (mist-like sulfuric acid component). Conventionally, a particulate filter is provided in the exhaust pipe through which gas flows.

[0003] This type of particulate filter has a porous honeycomb structure made of a ceramic such as cordierite or the like. The outlets of the passages that are not formed are plugged so that only the exhaust gas that has passed through the thin porous wall that defines each passage is discharged to the downstream side.

Since the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging. It is necessary to regenerate the curated filter.However, in a normal diesel engine operating state, there is little opportunity to obtain a high exhaust temperature enough for the particulates to self-combust. A catalyst regeneration type particulate in which an oxidation catalyst formed by adding an appropriate amount of a rare earth element such as cerium is integrally supported on the particulate filter, or an oxidation catalyst is separately disposed in front of the particulate filter. Employing a curated filter is being considered.

That is, if such a catalyst regeneration type particulate filter is employed, the oxidation reaction of the collected particulates is promoted to lower the ignition temperature, and the particulates are burned and removed even at a lower exhaust gas temperature than before. It is possible to do.

[0006]

However, even when such a catalyst regeneration type particulate filter is employed, the oxidation catalyst attached to the particulate filter has an active temperature range, Since an exhaust temperature of at least about 200 ° C. is required, an operating state at an exhaust temperature lower than this temperature (particularly, an area where the exhaust temperature is lower than about 200 ° C. is spread in a light load operation area). If it continues, there is a problem that the particulates are not satisfactorily burned and removed because the oxidation catalyst is not activated, and there is a possibility that the particulate filter may be clogged.

[0007] It has also been proposed to burn off particulates by forcibly heating with an electric heater, a burner or the like attached thereto. An electric system for supplying electricity to the electric heater, a fuel system for supplying fuel to the burner, and the like must be newly laid, which complicates the system for regenerating the particulate filter and costs. There was a problem that soared.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and the temperature of exhaust gas introduced into a ventilation type purifying material such as a catalyst regeneration type particulate filter is forcibly controlled by an electric heater or a burner. It is an object of the present invention to increase the operating range in which the ventilation type purifying material is active, so that the temperature can be raised without using a heating means.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an exhaust gas purifying apparatus equipped with a ventilated purifying material in the middle of an exhaust pipe for purifying exhaust gas by passing the exhaust gas. A heat radiating section is provided, and a heat absorbing section is provided at a position where the exhaust gas temperature is relatively high upstream of the heat radiating section, and the heat absorbing section and the heat radiating section are connected by a heat pipe. .

Thus, the heat absorption portion absorbs the heat of the exhaust gas having a relatively high temperature and transports the heat to the heat radiating portion through the heat pipe, and passes through the heat radiating portion. Since the temperature of the exhaust gas can be increased and introduced into the ventilation purifying material, the exhaust gas introduced into the ventilation purifying material can be operated even when the internal combustion engine is operating at a low exhaust temperature, such as during a light load operation. By raising the temperature of the gas, the activity of the ventilation type purifying material can be increased.

Further, in the present invention, in forming the heat absorbing portion and the heat radiating portion, at least one of the heat absorbing portion and the heat radiating portion is provided at an end of the heat pipe exposed to the flow of the exhaust gas, and at an outer peripheral surface of the end. In this case, the heat exchange area with the exhaust gas can be increased by the fins to realize efficient heat absorption or heat radiation.

In the present invention, the ventilation type purifying material may be a catalyst regeneration type particulate filter or a flow-through type catalyst monolith.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an engine which is a diesel engine. The engine 1 includes a turbocharger 2 and an air cleaner 3. Is sent to a compressor 2a of the turbocharger 2 through an intake pipe 5, and the intake air 4 pressurized by the compressor 2a is sent to an intercooler 6 for cooling. The intake air 4 is guided to 7 and distributed to each cylinder of the engine 1.

The exhaust gas 8 discharged from each cylinder of the engine 1 is sent to a turbine 2b of the turbocharger 2 through an exhaust manifold 9, and the exhaust gas 8 that drives the turbine 2b is exhausted through an exhaust pipe 10 to the outside of the vehicle. At an appropriate position on the downstream side of the exhaust pipe 10, a catalyst regeneration type particulate filter 11 is mounted and held by a filter case 12.

Here, the particulate filter 11 of the catalyst regeneration type is, for example, a filter obtained by adding an appropriate amount of a rare earth element such as cerium to a material obtained by supporting platinum on alumina. In the example shown here, the case where the oxidation catalyst is integrally supported on the particulate filter 11 is exemplified. However, the oxidation catalyst having the honeycomb structure of the flow-through system is used as the particulate filter. It is also possible to arrange them separately in front of 11.

The specific structure of the particulate filter 11 is as shown in FIG. 2. The particulate filter 11 has a porous honeycomb structure made of ceramic, and is divided into grids. Channel 11a
Are alternately plugged, and the outlet of the unsealed flow passage 11a is sealed, and the porous thin wall 11b defining each flow passage 11a is closed.
Only the exhaust gas 8 that has passed through is discharged to the downstream side.

The particulate filter 1
A heat radiating portion 13 described later is provided at a position immediately before 1, and near the outlet of the turbine 2 b of the turbocharger 2 upstream from the heat radiating portion 13, heat for transporting heat to the heat radiating portion 13 is provided. A heat absorbing portion 14 for absorbing the heat is provided, and a heat pipe 15 is provided between the heat absorbing portion 14 and the heat radiating portion 13.
Connected by

As shown in FIG. 3, the heat pipe 15 is made of a wick 16 made of a porous substance having a capillary action (for example, a braided metal wire or a sintered metal).
A volatile working fluid (a heat transport medium) is sealed in a pipe container 17 in which is fitted and mounted. The inside of the pipe container 17 is filled only with the working fluid and its saturated steam. Non-condensable gases such as air have been completely removed.

The heat absorbing portion 14 on the upstream side of the exhaust pipe 10
One end of the heat pipe 15 inserted from a direction substantially perpendicular to the axis of the exhaust pipe 10 so as to be exposed to the flow of the exhaust gas 8, and a plurality of heat pipes formed on the outer peripheral surface of the one end of the heat pipe 15 Various shapes can be applied to the fins 18, but the heat transfer surface formed by the fins 18 is restricted by the flow of the exhaust gas 8 of the exhaust pipe 10. It is along.

On the other hand, the heat radiating portion 13 immediately before the particulate filter 11 has substantially the same structure as the heat absorbing portion 14, and is inserted from a direction substantially perpendicular to the axis of the exhaust pipe 10 to allow the exhaust gas 8 to flow therethrough. And a plurality of fins 19 formed on the outer peripheral surface of the other end of the heat pipe 15, and the heat transfer surface formed by the fins 19 is also formed. The flow of the exhaust gas 8 in the exhaust pipe 10 is adapted.

According to the exhaust gas purifying apparatus described above, the heat of the exhaust gas 8 immediately after leaving the turbine 2b of the turbocharger 2 is transferred to the fins 18 by the heat absorbing portion 14.
And the like, is absorbed by one end of the heat pipe 15, the working fluid evaporates at one end of the heat pipe 15, and the evaporation causes a pressure difference between one end side and the other end side of the heat pipe 15, As shown by an arrow A in FIG. 3, the vapor of the working fluid moves toward the heat radiating portion 13 which is the other end of the heat pipe 15.

The steam that has moved to the heat radiating section 13 in the exhaust pipe 10 is condensed in the heat radiating section 13 to release latent heat, and the exhaust gas 8 passing through the heat radiating section 13 is passed through fins 19 and the like. The result of applying heat, the particulate filter 1
The temperature of the exhaust gas 8 introduced into 1 is increased.

As shown by an arrow B in FIG. 3, the condensed liquid of the working fluid in the heat radiating section 13 is returned to the heat absorbing section 14 by the capillary action of the wick 16, and further evaporation and condensation are repeated. .

Therefore, according to the above embodiment, the exhaust pipe 10
The heat held by the relatively high-temperature exhaust gas 8 on the upstream side is absorbed by the heat absorbing section 14, and the absorbed heat is thermally transferred to the heat radiating section 13 on the downstream side of the exhaust pipe 10 via the heat pipe 15. The exhaust gas 8 passing through the heat radiating section 13 is released, thereby raising the temperature of the exhaust gas 8 and increasing the temperature of the particulate filter 11.
Can be introduced.

That is, even when the engine 1 is in an operation state where the exhaust gas temperature is low such as when the engine 1 is under light load operation, the temperature of the exhaust gas 8 introduced into the particulate filter 11 is controlled by a forced heating means such as an electric heater or a burner. Since the temperature can be raised without using the filter, the operating range in which the filter regeneration oxidation catalyst of the particulate filter 11 is active can be expanded without causing a significant increase in cost.

Further, in the example shown here, the heat absorbing portion 14 and the heat radiating portion 13 are formed at the end of the heat pipe 15 exposed to the flow of the exhaust gas 8 and at the outer peripheral surface of the end. The fins 18 and 19 increase the heat exchange area with the exhaust gas 8 to ensure efficient heat absorption or heat radiation. The highly practical heat absorbing portion 14 and heat radiating portion 13 can be realized with a simple device configuration.

In the present embodiment, in particular, with respect to the engine 1 having the turbocharger 2, since the heat radiating portion 13 is provided near the outlet of the turbine 2b of the turbocharger 2, the engine 1 is provided to the turbine 2b. There is also an advantage that the efficiency of the turbocharger 2 can be maintained high by directly introducing the high-temperature and high-pressure exhaust gas 8 immediately after the exhaust.

FIG. 4 shows another embodiment of the present invention.
In the present embodiment, the engine 1 includes an EGR device that extracts a part of the exhaust gas 8 from the exhaust side and recirculates the exhaust gas 8 to the intake side, and one end of each cylinder in the exhaust manifold 9 in the direction in which the cylinders are arranged. A case in which a heat absorbing portion 14 is provided in the middle of an EGR pipe 20 that connects between one end of the intake pipe 5 connected to the EGR pipe 20 and recirculates the exhaust gas 8 is illustrated.

However, this type of EGR pipe 20 has
An EGR valve 21 for appropriately opening and closing the EGR pipe 20
And an EGR cooler 22 for cooling the exhaust gas 8 to be recirculated.
Since the temperature of the exhaust gas 8 can be lowered by exchanging heat between the cooling water (not shown) and the exhaust gas 8, the heat absorbing portion 14 is arranged upstream of the EGR cooler 22. good.

That is, the exhaust gas 8 recirculated to the engine 1
Is cooled in the middle of the EGR pipe 20, the temperature of the exhaust gas 8 decreases and the volume of the exhaust gas 8 decreases, so that the combustion temperature is reduced without significantly lowering the output of the engine 1, thereby effectively reducing the generation of NOx. It is possible, but EGR
The heat absorbing portion 14 is provided upstream of the cooler 22 so that the exhaust gas 8
In this case, the secondary effect of reducing the amount of heat collected by the EGR cooler 22 and reducing the load on the radiator can be obtained.

FIG. 5 shows still another embodiment of the present invention. In this embodiment, a heat absorbing portion is provided at one end of the exhaust manifold 9 in the direction in which the cylinders are arranged in the engine 1 having the turbocharger 2. In this case, heat is absorbed from the high-temperature and high-pressure exhaust gas 8 in the exhaust manifold 9 while being expanded by the turbine 2b. Turbine 2
The exhaust gas 8 whose temperature has dropped by about 100 to 200 ° C. from the inlet side of b can emit heat in the heat radiating unit 13, so that a sufficiently large exhaust gas temperature is provided between the heat absorbing unit 14 and the heat radiating unit 13. Can be set, and reliable heat transport by the heat pipe 15 can be performed.

Also, FIGS. 1 to 3, FIG.
In any of the embodiments shown in FIG. 5, it is possible to adopt a material other than the catalyst regeneration type particulate filter 11 as the ventilation type purifying material that is made to pass and purify the exhaust gas. For example, a flow-through type catalyst monolith 23 such as an NOx reduction catalyst as shown in FIG. 6 or an oxidation catalyst mainly for removing SOF in particulates may be used.

The exhaust gas purifying apparatus according to the present invention is not limited to the above-described embodiment, but is illustrated by one heat pipe for convenience of illustration in the figure. It can be arbitrarily selected according to the target heat exchange amount, and the structure of the heat absorbing portion and the heat radiating portion is not limited to the illustrated example. That the exhaust gas purifying apparatus of the present invention can be similarly applied by appropriately setting the temperature difference of the exhaust gas between the section and the heat radiating section, and that various changes can be made without departing from the gist of the present invention. Of course.

[0035]

According to the exhaust gas purifying apparatus of the present invention described above, the following various excellent effects can be obtained.

(I) To raise the temperature of exhaust gas introduced into a ventilation type purifying material such as a catalyst regeneration type particulate filter without using a forced heating means such as an electric heater or a burner. Therefore, the operating range in which the ventilated purifying material is active can be expanded without causing a significant increase in cost.

(II) In forming the heat absorbing section and the heat radiating section, at least one of them is formed on the end of the heat pipe exposed to the flow of the exhaust gas and on the outer peripheral surface of the end. If a structure composed of fins is adopted, the heat-exchanging area with the exhaust gas is increased by the fins, and a highly practical heat-absorbing portion and a heat-dissipating portion capable of reliably performing efficient heat absorption or heat dissipation can be easily provided. It can be realized with a structure.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment for implementing the present invention.

FIG. 2 is a sectional view schematically showing the structure of the particulate filter of FIG.

FIG. 3 is a sectional view schematically showing a basic structure of the heat pipe of FIG.

FIG. 4 is a schematic view showing another embodiment of the present invention.

FIG. 5 is a schematic view showing still another embodiment of the present invention.

FIG. 6 is a perspective view showing a catalyst monolith of a flow-through system with a part cut away.

[Explanation of symbols]

 Reference Signs List 8 Exhaust gas 9 Exhaust manifold 10 Exhaust pipe 11 Particulate filter (Vent-type purifying material) 13 Heat radiating unit 14 Heat absorbing unit 15 Heat pipe 18 Fin 19 Fin 20 EGR pipe 23 Catalyst monolith (Vent-type purifying material)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01N 3/24 B01D 53/36 K F Term (Reference) 3G090 AA02 AA03 BA01 EA05 EA06 3G091 AA10 AA11 AA18 AA28 AB02 AB05 AB13 BA00 BA11 CA01 CA07 CA13 FA02 FA04 FA12 FB02 FC07 HA14 HA15 HB03 HB05 HB06 4D048 AA14 AB01 BA03X BA19X BA30X BD01 BD10 CD05 4D058 MA41 MA60 SA08 TA06

Claims (4)

[Claims] 1. An exhaust gas purifier equipped with a ventilated purifying material in the middle of an exhaust pipe, which is provided with a ventilating purifying material for purifying exhaust gas through the exhaust gas. An exhaust emission control device, wherein a heat absorbing portion is provided at a position where the exhaust temperature is relatively high upstream of the portion, and the heat absorbing portion and the heat radiating portion are connected by a heat pipe. 2. At least one of the heat absorbing section and the heat radiating section is constituted by an end of the heat pipe exposed to a flow of exhaust gas and fins formed on an outer peripheral surface of the end. The exhaust gas purifying apparatus according to claim 1, wherein: 3. The particulate filter according to claim 1, wherein the ventilation type purifying material is a catalyst regeneration type particulate filter.
An exhaust gas purification device according to item 1. 4. The exhaust gas purifying apparatus according to claim 1, wherein the ventilation type purifying material is a flow-through type catalytic monolith.