JP2001173427A - Discharge regenerating type collecting filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge regenerating type collecting filter capable of preventing generation of the damage of a collecting filter, simplifying a structure, reducing device costs and running costs and preventing reduction of an engine performance. SOLUTION: A discharge electrode 12 is disposed in a first exhaust gas passage 10, and a charge electrode 11 is disposed in an exhaust gas leading surface 181, the discharge electrode 12 is brought into point-contact with an inner wall surface 130, and the charge electrode 11 is brought into electrically contact with an accumulated soot layer 80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge regeneration type collection filter installed in an exhaust system such as a diesel engine for collecting and removing soot and the like contained in exhaust gas.

[0002]

2. Description of the Related Art In order to collect and remove soot containing carbon and the like contained in exhaust gas of a diesel engine, a collecting filter made of a ceramic honeycomb or the like is installed in a diesel engine exhaust system. An exhaust gas passage is provided in the collection filter, and soot in the exhaust gas accumulates on the inner wall surface of the exhaust gas passage when passing through the exhaust gas passage. As a result, the exhaust gas that has passed through the collection filter hardly contains soot. However, if soot is deposited, the permeability of the trapping filter gradually deteriorates, the flow of exhaust gas deteriorates, and the pressure loss increases. Therefore, it is necessary to remove the soot deposited by appropriate means. Conventionally, soot deposited on the collection filter has been burned and removed by heating the collection filter using an electric heater, a burner, or the like provided outside the collection filter.

[0003]

However, when the collection filter is heated for the purpose of burning and removing soot, the heat of combustion of the soot may cause uneven temperature in the collection filter and cause cracks and the like. Further, the trapping filter may be damaged by the heat of combustion. In addition, the provision of the electric heater and the burner complicates the configuration of the collection filter and the entire engine exhaust system, and also requires the installation cost and running cost of the electric heater and the burner, resulting in an increase in cost.

The present invention has been made in view of the above-mentioned conventional problems, and has been made in view of the above-mentioned problems. Therefore, the discharge filter is hardly damaged, the construction is simple, the apparatus cost and running cost are low, and the engine performance is hardly deteriorated. It is intended to provide an expression collecting filter.

[0005]

According to a first aspect of the present invention, there is provided a first exhaust gas passage having an exhaust gas introduction surface opened and an exhaust gas outlet surface closed, and an adjoining first exhaust gas passage separated by a partition wall. At least one set of a second exhaust gas passage having a closed exhaust gas introduction surface and an open exhaust gas outlet surface is provided, and the exhaust gas introduced into the first exhaust gas passage is passed through the partition to the second exhaust gas passage. And a discharge electrode is provided in at least a part of the first exhaust gas passage in parallel with a flow direction of the exhaust gas, and a discharge electrode is provided in the exhaust gas introduction surface. A charging electrode having a polarity capable of generating a discharge with the discharge electrode is provided, and the discharge electrode is configured to make point contact with an inner wall surface of the first exhaust gas passage. ， Introduced exhaust gas Soot is in the discharge regenerative collection filter, characterized in that is configured to be in electrical contact with the formed deposited soot layer by depositing on the inner wall surface of the first exhaust gas passage in.

The most remarkable point of the present invention is that a discharge electrode is provided on at least a part of the first exhaust gas passage, a charging electrode having a different polarity is provided on an exhaust gas introduction surface, and the charging electrode is provided on an inner wall surface of the exhaust gas passage. That is, it is configured to be able to make electrical contact with the deposited soot layer. The polarity of the charging electrode and the polarity of the discharging electrode may be configured so as to enable discharge between them. For example, the discharging electrode may be positive, the charging electrode may be negative, or vice versa. Further, one of the discharge electrode and the charging electrode may be grounded.

Next, the operation of the present invention will be described. A charging electrode is provided on the exhaust gas introduction surface of the discharge regeneration type collection filter according to the present invention. By the way, the discharge regeneration type trapping filter according to the present invention is configured such that an exhaust gas introduction surface is opened and an exhaust gas outlet surface is closed, and a first exhaust gas passage is adjacent to the first exhaust gas passage with a partition wall therebetween. A second exhaust gas passage having an inlet surface closed and an exhaust gas outlet surface opened; The exhaust gas introduced from the exhaust gas introduction surface enters the second exhaust gas passage from the first exhaust gas passage via the partition wall, and is discharged outside from the exhaust gas discharge surface.

[0008] Therefore, the soot is introduced into the discharge regeneration type collection filter together with the exhaust gas.
It deposits on the inner wall of the exhaust gas passage and forms a soot layer from the exhaust gas introduction surface to the exhaust gas outlet surface. The deposited soot layer and the charging electrode are configured to be electrically contactable, and soot in the exhaust gas is conductive. Therefore, the deposited soot layer functions as an electrode having the same polarity as the charged electrode.

The discharge electrode is installed so as to make point contact with the inner wall surface of the first exhaust gas passage. Therefore, the electric field strength of the discharge electrode is highest at the point where it makes point contact with the inner wall surface. Therefore, discharge occurs between the point contact point and the deposited soot layer. Generally, soot has a fine and porous particle size of about 1 μm, and easily generates and burns by the discharge. As described above, the vicinity of the point of contact of the discharge electrode in the deposited soot layer is burned and removed by the discharge.

Further, for example, in a portion where the discharge electrode is not in point contact, such as a corner portion of the first exhaust gas passage as shown in an embodiment to be described later or the like, discharge does not occur or hardly occurs, so that the deposited soot layer remains as it is. . Since the remaining deposited soot layer has the same polarity as the charged electrode and functions as an electrode formed in the first exhaust gas passage, soot is deposited again in the future, and a deposited soot layer is formed up to a point contact point between the discharge electrode and the inner wall surface. Then, since these deposited soot layers have the same polarity as the charged electrodes, a discharge occurs between the deposited soot layers and the discharge electrodes, and the soot in the deposited soot layers can be burned and removed.

As described above, the soot layer is provided on the introduction surface of the collection filter by utilizing the fact that soot is mainly conductive, without previously forming an electrode that is paired with the discharge electrode in the first exhaust gas passage. It can function as an electrode having the same polarity as the charged electrode.

Further, since the deposited soot layer is gradually burned by the discharge, the pressure loss of the discharge regeneration type trapping filter does not increase, and the temperature of the trapping filter is prevented from being partially high, so that the trapping filter is hardly damaged. . In addition, for the same reason, erosion of the collection filter hardly occurs.

Further, only the discharge electrode may be provided in the first exhaust gas passage of the discharge regeneration type collection filter, and the charging electrode paired with the discharge electrode is provided outside the collection filter, which is the exhaust gas introduction surface, to perform its function. Can be demonstrated. For this reason, since the configuration of the collection filter is simple and easy to manufacture, the cost can be reduced.

Furthermore, the running cost is low because power is hardly consumed until actual discharge occurs. In addition, since the discharge gradually starts as the soot is deposited and can be burned off continuously, the first exhaust gas passage is always clear and the flow of the exhaust gas is hardly hindered. For this reason, the engine back pressure is unlikely to increase, and a decrease in engine performance can be prevented.

As described above, according to the present invention, it is possible to provide a discharge regeneration type collection filter which is less likely to cause damage to the collection filter, has a simple structure, is inexpensive in equipment costs and running costs, and hardly deteriorates engine performance. it can.

Next, as in the second aspect of the present invention, it is preferable that the discharge electrode is a helical wire or a wire having a protrusion protruding from a side surface. As a result, the discharge starting voltage can be reduced, and the wear and damage of the discharge electrode due to the discharge can be reduced.

In the spiral wire, the outer peripheral side of the spiral is a portion that makes point contact with the inner wall surface of the first exhaust gas passage. In the case of a wire having the above-mentioned projection, the tip of each projection is a portion that makes point contact with the inner wall surface of the first exhaust gas passage. Further, in the case of a discharge electrode formed of a wire having the above-mentioned protrusion, it is preferable that the number of protrusions is larger. This is because the discharge is generated at a point where the inner wall surface of the first exhaust gas passage and the discharge electrode are in point contact with each other.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A discharge regeneration type trapping filter according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a discharge regeneration type trapping filter 1 (hereinafter referred to as trapping filter 1) according to this embodiment has an exhaust gas introduction surface 181 opened and an exhaust gas outlet surface 182 closed, and a first exhaust gas passage 10.
A large number of second exhaust gas passages 101 are provided adjacent to the first exhaust gas passage 10 with the partition wall 13 therebetween, closing the exhaust gas introduction surface 181 and opening the exhaust gas discharge surface 182.
And the exhaust gas 3 introduced from the first exhaust gas passage 10
Enters the second exhaust gas passage 101 via the partition wall 13 and is led out from the exhaust gas outlet surface 182 to the outside.

The first exhaust gas passage 10 is provided with a discharge electrode 12 parallel to the exhaust gas flow direction. The charging electrode 11 which is a negative electrode is provided on the exhaust gas introduction surface 181.
In addition, the discharge electrode 12 partially has the first exhaust gas passage 1.
It is configured to make point contact with the inner wall surface 130 of the “0”. As shown in FIG. 3, the charging electrode 11 is configured to be able to electrically contact the soot layer 80 formed by the soot in the introduced exhaust gas 3 being deposited on the inner wall surface 130 of the first exhaust gas passage 10. Have been. Therefore, the deposited soot layer 80 functions as a negative electrode.

The details will be described below. The collection filter 1 of the present embodiment is a columnar cordierite ceramic honeycomb body as shown in FIGS. 1 and 2, and has a large number of first and second exhaust gas passages 10 and 101 having a rectangular cross section therein. Further, the honeycomb body is made of a gas-permeable porous body. The trapping filter 1 is installed in the exhaust system of the diesel engine such that the exhaust gas 3 is introduced from the exhaust gas introduction surface 181 on the left side of the drawing and the purified exhaust gas 30 is extracted from the exhaust gas discharging surface 182 on the right side of the drawing ( (See FIG. 4).

Further, as shown in FIG.
, The second exhaust gas passage 101 provided with the plug 141 on the introduction surface 181 side and the first exhaust gas passage 10 provided with the plug 142 on the outlet surface 182 side are arranged adjacent to each other. The honeycomb body has a circular cross section and the exhaust gas introduction surface 18
The diameter of one side is 140mm and the length in the exhaust gas flow direction is 14
0 mm.

The exhaust gas 3 is introduced into the collection filter 1 from the first exhaust gas passage 10 as shown in FIG.
As shown in (a), the second exhaust gas passage 10 adjacent from the inner wall surface 130 in the middle of the first exhaust gas passage 10 via the partition 13 is provided.
1 and is then led out of the collection filter 1. When moving from the first exhaust gas passage 10 to the second exhaust gas passage 101, soot contained in the exhaust gas 3 is left on the surface of the inner wall surface 130. Thus, the deposited soot layer 80 is formed on the inner wall surface 130 as shown in FIG.

The first exhaust gas passage 10 has a structure shown in FIGS.
As shown in FIG. 3, a discharge electrode 12 made of a metal spiral wire having a diameter of 0.1 to 1.0 mm is arranged.
The end of 2 is drawn out of the collection filter 1 through the plug 142 of the first exhaust gas passage 10. As is known from FIG. 1, a charging electrode 11 is provided on an exhaust gas introduction surface 141 of the collection filter 1. Charging electrode 11 is inner wall 1
A thin-film electrode provided on the side of 30 is made by baking Pt paste. Each of the charging electrode 11 and the discharging electrode 12 is connected to a circuit 190 provided with a power source 19 so that a potential difference between the two electrodes can be applied to enable discharge.

The collection and removal of soot in the exhaust gas 3 by the collection filter 1 of this embodiment will be described. Electric current is supplied to the discharge electrode 12 and the charging electrode 11, and the exhaust gas 3 is introduced into the collection filter 1. As shown in FIGS. 1 and 3A, the introduced exhaust gas 3 passes through the inner wall surface 130 from the first exhaust gas passage 10 to the second exhaust gas passage 10.
It flows to the exhaust gas passage 101. Therefore, as shown in FIG. 3B, soot is deposited on the surface of the inner wall surface 130 with the passage of time, and the deposited soot layer 80 is formed. As the sedimentary soot layer 80 grows, the sedimentary soot layer 80 becomes the exhaust gas introduction surface 181.
To contact the charging electrode 11. Therefore, the deposited soot layer 80 is negatively charged by the charging electrode 11 and functions as an electrode. Therefore, the point between the discharge electrode 12 and the inner wall surface 130 at the point of contact (part A shown in FIG. Discharge occurs.

The discharged soot layer 80 is heated by the discharge, and the soot is burned and removed. Therefore, as shown in FIG. 4B, the side inner wall surface 131 near the portion A where the discharge has occurred is deposited on the soot layer 8.
0 is removed, and the exhaust gas 3 again flows from the inner wall surface 130 through the partition wall 13. The corner 132
In this case, since the discharge electrode 12 has no point where it makes point contact, almost no discharge occurs, and the deposited soot layer 80 remains as it is.

Thereafter, the deposited soot layer 80 is again placed on the side inner wall surface 1.
The discharge is generated from the same process as described above, and the deposited soot layer 80 is removed again. Corner 1
The deposited soot layer 80 remaining at 32 constantly conducts with the charging electrode 11 and functions as an electrode in the first exhaust gas passage 10 having the same polarity as the charging electrode 11. With the above mechanism, the collected soot can be automatically removed in the discharge regeneration type collection filter 1.

Next, the performance of the discharge regeneration type collection filter 1 according to the present embodiment is measured, and the results will be described. Simple testing machine 4 equipped with actual diesel engine 4
9 was prepared. The structure of the tester 49 is shown in FIG. The collection filter 1 of this example is installed in the exhaust system 41 connected to the exhaust part of the actual engine 4. A differential pressure gauge 45 is installed on the inlet side and the outlet side of the collection filter 1 to measure a pressure difference between the inlet side and the outlet side of the collection filter 1. The charging electrode 11 provided on the exhaust gas introduction surface 182 of the collection filter 1 and a number of discharge electrodes 12 in the exhaust passage 10 are connected to a power supply 43.

The power source 43 applies a frequency of 6 to the discharge electrode 12.
A sine wave AC voltage of 0 Hz and an effective value of 500 V was applied, and then the actual engine 4 was driven at a rotation speed of 2,000 rpm with a low load to generate exhaust gas. As a result, as can be seen from FIG. 6, the pressure loss of the collection filter 1 obtained from the differential pressure gauge 45 uniformly increased for a while immediately after the engine was driven, but hardly changed from a certain time.
This is because the soot burns due to the discharge and the air permeability improves.

As a comparative example, the same test as above was performed without applying a voltage to the discharge electrode 12. As a result, as can be seen from FIG. 6, the pressure loss continued to increase. This causes soot to accumulate on the inner wall surface 130 over time,
This is because it has become difficult for the exhaust gas 3 to move from the first exhaust gas passage 10 to the second exhaust gas passage 101 from the inner wall surface 130 via the partition wall 13.

Next, the operation and effect of this embodiment will be described. In this example, the charging electrode 11 is provided on the exhaust gas introduction surface 181 of the collection filter 1. The soot is introduced into the collection filter 1 together with the exhaust gas 3, and is deposited on the inner wall surface 130 of the exhaust gas passage.
The deposited soot layer 80 extending from the exhaust gas introduction surface 181 to the exhaust gas outlet surface 182 is formed. Since the deposited soot layer 80 and the charging electrode 11 are configured to be electrically contactable, they are electrically connected, and the deposited soot layer 80 functions as a negative electrode similarly to the charging electrode 11. Therefore, a discharge can be generated between the deposited soot layer 80 and the discharge electrode 12.

The portion deposited on the side inner wall surface 131 of the deposited soot layer 80 is burned and removed by the discharge. Corner 1
In 32, since the deposited soot layer 80 does not make point contact with the inner wall surface 130, no discharge occurs, and the deposited soot layer 80 remains as it is. The remaining deposited soot layer 80 conducts with the charging electrode 11, and thereafter functions as a negative electrode paired with the discharge electrode 12 in the first exhaust gas passage 10.

As described above, in the present embodiment, since the deposited soot layer 80 is gradually burned off by the discharge, the pressure loss of the filter does not increase, and the temperature of the trapping filter 1 is prevented from being partially high. You. Therefore, heat damage and erosion hardly occur.

The discharge electrode 12 is provided in the first exhaust gas passage 10.
Only need to be installed, and the charging electrode 11 is the exhaust gas introduction surface 1
81 can be provided outside the collection filter 1. Therefore, the configuration is simple, the production is easy, and the cost is low.

Furthermore, the running cost is low because the power is hardly consumed until the actual discharge occurs. In addition, since the soot is gradually discharged, burned, and removed as the soot is deposited, the first exhaust gas introduction passage 10 is always clear and the flow of the exhaust gas is hardly hindered. For this reason, the engine back pressure is unlikely to increase, and a decrease in engine performance can be prevented.

As described above, according to the present embodiment, it is possible to provide a discharge regeneration type collection filter in which the collection filter is hardly damaged, the configuration is simple, the apparatus cost and the running cost are low, and the engine performance is hard to lower. it can.

The discharge electrode 12 is shown in FIG.
As shown in (b), a wire made of a wire having a protrusion 125 protruding from the side surface can be used. The discharge electrode 12 is installed such that the tip of the protrusion 125 is in point contact with the inner wall surface 130 of the exhaust gas passage, and discharge is generated mainly around the tip of the protrusion 125. With the discharge electrode 12 having such a configuration, the same operation and effect as those of the above-described embodiment can be obtained.

[0037]

As described above, according to the present invention, there is provided a discharge regeneration type collection filter which is less likely to cause damage to the collection filter, has a simple structure, is inexpensive in equipment cost and running cost, and hardly deteriorates engine performance. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view of a discharge regeneration type collection filter in an embodiment.

FIG. 2 is an explanatory diagram of a discharge regeneration type collection filter in the embodiment.

FIGS. 3A and 3B are cross-sectional explanatory views of a first exhaust gas passage according to an embodiment, and FIGS.
Sectional explanatory drawing of an exhaust gas passage.

4A and 4B are cross-sectional explanatory views of a first exhaust gas passage in the vicinity of a corner portion, and FIG. 4B is a cross-sectional explanatory view of a state in which a deposited soot layer remains only at a corner portion in the embodiment.

FIG. 5 is an explanatory diagram showing a configuration of a tester in the embodiment.

FIG. 6 is a diagram showing the relationship between time and pressure loss in the present embodiment and a comparative example in the embodiment.

7A and 7B are explanatory diagrams of an exhaust gas passage provided with another discharge electrode, and FIG. 7B is an explanatory diagram of a discharge electrode in the embodiment.

[Explanation of symbols]

 1. . . 9. discharge regeneration type collection filter, . . First exhaust gas passage, 101. . . 10. second exhaust gas passage, . . Charged electrode, 12. . . Discharge electrode, 13. . . Partition wall, 130. . . Inner wall surface, 181. . . Exhaust gas introduction surface, 182. . . 2. Outgassing surface, . . Exhaust gas,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Jintori 41-Cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. 41, Yokomichi, F-term in Toyota Central R & D Laboratories Co., Ltd. 3G090 AA02 BA01

Claims (2)

[Claims] An exhaust gas introduction surface is opened and an exhaust gas outlet surface is closed, and a first exhaust gas passage is adjacent to the first exhaust gas passage with a partition wall therebetween. At least one set of a second exhaust gas passage having an open surface is provided. Exhaust gas introduced into the first exhaust gas passage enters the second exhaust gas passage through the partition wall and is discharged from the exhaust gas outlet surface to the outside. A discharge electrode is provided in at least a part of the first exhaust gas passage in parallel with a flow direction of the exhaust gas, and a discharge can be generated between the discharge electrode and the exhaust gas introduction surface. And a discharge electrode having the following polarity:
The charging electrode is configured to be in point contact with the inner wall surface of the first exhaust gas passage, and the charging electrode includes a deposited soot layer formed by depositing soot in the introduced exhaust gas on the inner wall surface of the first exhaust gas passage. A discharge regeneration type collection filter characterized by being configured to be electrically contactable. 2. The discharge regeneration type collection filter according to claim 1, wherein the discharge electrode is a spiral wire or a wire having a protrusion on a side surface.