JPH0598937A - Exhaust emission control device for diesel engine - Google Patents

Abstract

PURPOSE:To maintain the exhaust emission control function to recondition filters well. CONSTITUTION:At the time of reconditioning, a second valve 7 is closed to a predetermined open degree to throttle the exhaust, and after reconditioning filters 23a-23c of a second purification chamber 15 by a heater 29, a third valve 9 is closed to a predetermined open degree to throttle the exhaust, and filters 23a-23c of a third purification chamber 17 are reconditioned by a heater 31. At a reconditioned part, the exhaust quantity is reduced to a fine quantity, and the temperature rise effect by the heaters 29, 31 and the combustion efficiency by the heat transmission are improved, and at a part, which is not reconditioned, exhaust emission control efficiency is improved by activation of the catalyst to be caused by temperature rise of the reconditioned part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas cleaning device for a diesel engine equipped with an exhaust particle collecting member for collecting exhaust particles.

[0002]

2. Description of the Related Art Exhaust particles such as carbon are contained in the exhaust gas of a diesel engine, and it is not preferable to release the exhaust particles into the atmosphere as one of the causes of air pollution. As one of methods for removing the exhaust particulates from the exhaust gas, a method of providing a filter as an exhaust particulate collecting member in an exhaust passage of an engine and collecting the exhaust particulates by allowing the exhaust gas to pass through the filter is conventionally known. ing. According to this method, the exhaust pressure increases as the amount of the exhaust particulates adhering to the filter increases, which may adversely affect the engine performance. Therefore, the collected exhaust particulates are regularly removed by burning or the like. Filter regeneration processing is required.

As a conventional regenerator for regenerating a filter, a burner is used to combust exhaust particulates (see Japanese Patent Laid-Open No. 60-135612), and unburned fuel is supplied into the exhaust gas into the filter. That burns the exhaust particulates by oxidizing the fuel by means of oxidization (JP-A-56-130)
No. 545, JP-A-59-162316 and JP-A-61-112716), an additive for lowering the combustion temperature of exhaust particulates is usually supplied to the fuel supplied to the engine or the exhaust gas discharged from the engine. (See Japanese Patent Laid-Open No. 60-153413) that burns exhaust particulate at the exhaust temperature, and one that burns exhaust particulate by providing a heater immediately before the filter (Japanese Laid-Open Patent Publication No. 59-90713 and Japanese Laid-Open Patent Publication No. 59-90713). JP-A-59-162316) is proposed.

Among them, the regenerator using a burner has a complicated structure because a fuel supply device and an ignition device are provided in the exhaust passage, and a flame is generated during the exhaust, so that the exhaust passage has corrosion resistance and structural characteristics. It is necessary to improve the strength,
It cannot be easily implemented for structural reasons. Similarly, the regenerator that supplies unburned fuel to the exhaust gas also requires a catalyst and a fuel supply device that oxidize the supplied unburned fuel, and cannot be easily implemented structurally. In addition, since the supplied additive is highly likely to be released into the atmosphere in the regenerator that supplies the additive, it may cause a new air pollution depending on the component of the additive. Difficult to do.

On the other hand, the regenerator using the heater is superior to other regenerators in that it is less likely to complicate the structure or generate new air pollution. However, when the heater is operated by the electric power supply source for the vehicle configured by the battery and the alternator to heat the exhaust gas and burn the exhaust particulates, there is a limit to the amount of heat supplied by the heater, so the exhaust gas temperature can be increased efficiently. In order to increase the exhaust gas, the exhaust gas is bypassed to the filter during regeneration to reduce the amount of exhaust gas flowing into the filter. For this reason, during such regeneration, there is a problem that a considerable amount of exhaust gas does not pass through the filter and is discharged while containing exhaust gas particulates.
There is one in which two filters are provided in parallel, and exhaust gas flows into the other filter when one filter is regenerated (see Japanese Patent Laid-Open No. 57-65813).

[0006]

However, in such a regeneration processing apparatus in which the filters are provided in parallel, is one filter regenerating the other when the exhaust particulates are collected? , Or because the trapping action is stopped, the exhaust purification performance obtained is inferior despite the provision of the two filters, and if the filter is enlarged to improve the exhaust purification performance, the exhaust purification device itself Will become larger. It is also possible to use both filters when not playing, but in this case as well, only one filter will be used during playing, so the collection performance during playing will be There is a problem that it is significantly reduced compared to other cases.

The present invention has been made in order to solve such a conventional problem, and an object thereof is to obtain a device itself even at the time of regeneration for heating and removing the collected exhaust particulates. It is an object of the present invention to provide an exhaust gas purification device for a diesel engine, which can maintain a desired collection efficiency of exhaust particulates without causing an increase in size.

[0008]

In order to achieve the above object, an exhaust gas purification device for a diesel engine according to a first aspect of the present invention has a central first purification chamber and a first purification chamber located on both sides of the central purification chamber by partition walls. There is a container partitioned into a second purification chamber and a third purification chamber, and a collection member that collects exhaust fine particles in the exhaust gas by passing the exhaust gas through the partition wall is provided in the container. It is arranged. This collecting member carries a catalyst, which can oxidize and reduce SOF such as unburned HC in exhaust particulates due to the oxidizing ability of the catalyst, and at the catalyst activation temperature or below, reduces the above SOF by adsorption and further Regardless of the activity, it collects and reduces fine particles such as carbon. In addition, the collecting member includes a heating unit that burns and removes the collected exhaust particulates, and connects the first purification chamber with a first exhaust passage that guides exhaust gas from the first purification chamber. The second and third purification chambers are connected to second and third exhaust passages for introducing exhaust gas into the second and third purification chambers, and the amount of exhaust gas flowing through these passages to the second and third exhaust passages. It is characterized in that an exhaust flow rate adjusting means for adjusting the above is provided.

Further, in the exhaust gas purifying apparatus for a diesel engine according to a second aspect, the inside is divided into a first purification chamber in the center by a partition wall, and a second purification chamber and a third purification chamber located on both sides of the first purification chamber. Having a partitioned container, a collection member that collects exhaust particulates in the exhaust gas by passing the exhaust gas through the partition wall is disposed in the container, and the collection member is a catalyst. A second purification chamber heating means and a third purification chamber heating means for burning and removing the collected exhaust particulates are provided at the respective portions that are carried and located in the second and third purification chambers, respectively. The purification chamber is connected to the first exhaust passage leading out the exhaust from the first purification chamber, while the second and third purification chambers are connected to the second and third exhaust passages introducing the exhaust into the second and third purification chambers. Adjust the amount of exhaust gas flowing through each of the second and third exhaust passages. Exhaust flow rate adjusting means is provided, and when operating the second purification chamber heating means, the exhaust flow rate adjusting means provided in the second exhaust passage is adjusted to reduce the exhaust flow rate, while operating the third purification chamber heating means. Sometimes, the control means is provided to adjust the exhaust flow rate adjusting means provided in the third exhaust passage to reduce the exhaust flow rate.

[0010]

According to the exhaust gas purification device of the first aspect of the present invention, when both the exhaust flow rate adjusting means of the second and third exhaust passages are opened, the exhaust gas is connected to the respective exhaust passages. Since it flows into the third purification chamber and spreads over the entire area of the collecting member substantially uniformly, exhaust particulates are collected and reduced over the entire area of the collecting member. Further, when either one of the exhaust flow rate adjusting means provided in the second and third exhaust passages is closed, the amount of the exhaust gas flowing into the purification chamber connected to the passage on the closed side is reduced, so that heating is performed in this state. By operating the means, the heating operation by the heating means in the collecting member here is efficiently performed. Further, at this time, the collection member on the collection side is heated by the heat generated by the collection member on the regeneration side, so that the activity of the catalyst carried on the collection member is improved, so that the SOF in the exhaust particulate matter is improved. The oxidation reduction performance of is improved.

According to another aspect of the exhaust gas cleaning apparatus for a diesel engine of the present invention, the control means adjusts the exhaust flow rate adjusting means provided in the second exhaust passage when operating the second purifying chamber heating means. The flow rate is decreased, and when operating the third purification chamber heating means, the exhaust flow rate adjusting means provided in the third exhaust passage is adjusted to reduce the exhaust flow rate.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of an embodiment of an exhaust gas cleaning device for a diesel engine according to the present invention, FIG. 2 is a plan sectional view of FIG. 1, and FIG. 3 is a sectional view taken along line AA of FIG. Is.

An exhaust passage connected to an engine body (not shown) branches into a second exhaust passage 1 and a third exhaust passage 3 on the way and is connected to a filter case 5 as a container. The second exhaust passage 1 and the third exhaust passage 3 are provided with a second valve 7 and a third valve 9 as exhaust flow rate adjusting means for adjusting the opening of each exhaust passage to reduce the inflow amount of exhaust. ing.

Inside the filter case 5, two partition walls 1 are provided.
1, 13 divided into three parallel purification chambers,
The second purification chamber 15 and the third purification chamber 17 located at both ends are connected to the second exhaust passage 1 and the third exhaust passage 3, and the first purification chamber 19 located in the center has the first purification chamber 19. A first exhaust passage 21 for communicating the exhaust gas inside the chamber 19 to the outside of the filter case 5 is connected and connected. Further, in the filter case 5, three filters 2 as a collection member for collecting exhaust particulates in the exhaust gas by allowing the exhaust gas to pass therethrough.
3a, 23b and 23c are arranged so as to penetrate the two partition walls 11 and 13. As a result, the three purification chambers 15,
The filters 17a, 19b are in communication with each other by the filters 23a, 23b, 23c, and the exhaust gas that has flowed into the filter case 5 from the second exhaust passage 1 or the third exhaust passage 3 is in the second exhaust passage.
From the purification chamber 15 or the third purification chamber 17 to the filters 23a,
After passing through 23b and 23c, it flows into the first purification chamber 19 and flows out from the first exhaust passage 21.

The filters 23a, 23b, 23c are filled in a metal plate 25 such as a punching metal which is formed in a hollow cylindrical shape and has a plurality of predetermined ventilation holes on the outer peripheral surface, and a hollow portion surrounded by the metal plate 25. The pellet catalyst 27 is constituted by a pellet catalyst 27. The pellet catalyst 27 collects and collects exhaust fine particles in the exhaust gas and SOF which is unburned HC in the fine particles.
Adsorb and reduce oxidation. In addition, the filters 23a, 23b, 2 in the second purification chamber 15 and the third purification chamber 17
Coil-shaped heaters 29 and 31 as heating means are provided on the outer peripheral portion of 3c so as to wind around the outer peripheral portion.

The heaters 29 and 31 constitute a second cleaning chamber heating means and a third cleaning chamber heating means, respectively, which are heated separately by receiving an energization signal from a control unit 33 including a microcomputer. Filter 2
Exhaust particulates adhering to 3a, 23b and 23c are burned and removed to regenerate the filters 23a, 23b and 23c. In the control unit 33, for example, a regeneration timing detection circuit 35 that detects the regeneration timing by a method based on the operation history of the engine or a method based on the differential pressure across the filter.
And a reproduction control circuit 37 as a control means. Upon receiving the output signal from the regeneration timing detection circuit 35, the regeneration control circuit 37 first outputs a signal to the second valve 7 to throttle the exhaust gas in the second exhaust passage 1 and to inflow the exhaust gas into the second purification chamber 15. Is reduced and a signal is output to the heater 29 of the second purification chamber 15 to output the filters 23a, 23b, 23.
Heat c. If this state elapses for a predetermined time, the second
After opening the valve 7 to stop energizing the heater 29,
A signal is output to the third valve 9 to throttle the exhaust gas in the third exhaust passage 3 to reduce the inflow amount of the exhaust gas into the third purification chamber 17, and a signal is output to the heater 31 of the third purification chamber 17 to output the filter 23a. , 23b, 23c are heated, and the throttle of the third valve 9 and the heater 31 are energized for a predetermined time.

Next, the operation of the exhaust gas cleaning device according to this embodiment having the above-mentioned structure will be described.

During normal times when the filters 23a, 23b, 23c are not regenerated, both the second valve 7 and the third valve 9 are opened, and the exhaust gas discharged from the engine body of the diesel engine (not shown) becomes the second exhaust gas. It passes through the exhaust passage 1 and the third exhaust passage 3, flows into the second purification chamber 15 and the third purification chamber 17, and goes from the second purification chamber 15 and the third purification chamber 17 at both ends to the central first purification chamber 19. Filter 23a, 23
Pass through b and 23c. At this time, the carbon in the exhaust particulates in the exhaust is adhered and collected by the pellet catalyst 27 in the filters 23a, 23b, 23c, and the SOF in the exhaust particulates is adsorbed and reduced in oxidation. Is purified and flows out from the first exhaust passage 21.

Further, at this time, since almost the same amount of exhaust gas flows into the second purification chamber 15 and the third purification chamber 17, the filters 23a, 23b and 23c are in the second purification chamber 15 and the third purification chamber. The carbon in the exhaust particulate is collected almost uniformly without being biased in the chamber 17, and the SOF is also uniformly adsorbed.

When the amount of exhaust particulates deposited on the filters 23a, 23b, 23c exceeds a predetermined amount, the regeneration timing detection circuit 35 detects the regeneration timing and outputs a signal to the regeneration control circuit 37. The reproduction control circuit 37 includes the reproduction time detection circuit 3
When the signal output from 5 is received, the second valve 7 is closed to a predetermined opening degree, the exhaust gas in the second exhaust passage 1 is throttled, and the exhaust amount is reduced to a state where the exhaust gas hardly flows into the second purification chamber 15. At the same time, the heater 29 of the second purification chamber 15 is energized and the filters 23a, 23b, 23c of the second purification chamber 15 are energized.
To heat. At this time, since the amount of exhaust gas flowing into the second purification chamber 15 is very small, the filter 23 by the heater 29 is used.
The heating of a, 23b, and 23c is efficiently performed. Also,
When a part of the accumulated exhaust particulates begins to burn, the combustion is sequentially propagated by a small amount of exhaust gas flowing into the filters 23a, 23b, 23c, and the filters 23a, 23b, 2
Since even the exhaust particulates accumulated inside 3c can be combusted sufficiently, the exhaust particulates can be reliably burned even with a heater having a small capacity.

In this way, the heater 29 of the second purification chamber 15
To the filters 23a, 23b of the second purification chamber 15,
When regenerating 23c, almost all of the exhaust gas is
Since the gas flows from the exhaust passage 3 into the third purification chamber 17, the exhaust gas does not have to be directly discharged into the atmosphere. Further, at this time, approximately twice the exhaust gas from the normal state is discharged from the third purification chamber 17 to the first purification chamber 1.
9 will pass through the filters 23a, 23b, 23c. However, at this time, the filters 23a, 23b, 23c of the third purification chamber 17 are heated by the heat of combustion of the exhaust particulates in the second purification chamber 15 and the heat of the heater 29, so that the temperature becomes higher than in the normal state, so the filter 29
a, 29b, 29c pellet catalyst is more activated,
Since the oxidation reduction performance of SOF is significantly improved, the exhaust gas purification efficiency by the filters 23a, 23b, 23c is improved. Therefore, the filters 23a, 23 of the second purification chamber 15
Even during the regeneration of b and 23c, it is possible to almost eliminate the deterioration of the purification performance as compared with the case where the entire filter is used for collection. Further, even when the filter is regenerated by using one side of the filter, the purification performance hardly deteriorates, so that the filter does not need to be so large, and the increase in size of the device itself can be avoided.

When the heater 29 of the second purification chamber 15 has been energized for a predetermined time, the regeneration control circuit 37 stops energizing the heater 29 and opens the second valve 7, and then turns on the third valve 9. The heater 3 of the third purification chamber 17 is closed to a predetermined opening degree.
Energize 1. Thereby, similarly to the case of the second purification chamber 15, the filters 23a, 23 of the third purification chamber 17 are now turned on.
b and 23c are regenerated and the filter 23 of the second purification chamber 15 is regenerated.
Exhaust gas is purified by a, 23b, and 23c. When energization of the heater 31 of the third purification chamber 17 reaches a predetermined time, the regeneration control circuit 37 stops energization of the heater 31 to open the third valve 9, and filters 23a, 23b, 2
The reproduction process of 3c is completed. As a result, the filter 23
Almost all of a, 23b, and 23c are reproduced.

The heater 29 or the heater 31 can be energized simultaneously or sequentially with respect to the three filters 23a, 23b and 23c. Further, although three filters are used in this embodiment,
This number is not necessarily limited to three. However, if the diameter of the filter is large, it is necessary to increase the capacity of the heater for regeneration of the filter by that amount. Therefore, it is possible to suppress the energy consumption by using a plurality of filters having a small diameter.

Further, in this embodiment, the heater is provided on the outer peripheral portion of the filter, but the heaters 39 and 41 may be provided on the inner peripheral portion of the filters 23a, 23b and 23c as shown in FIG. The collecting member may be a porous material such as a ceramic foam filter 45 as shown in FIGS. 5 and 6, which carries a catalyst, and the heating means may be as shown in FIGS. 7 and 8. Electrodes 47 and 49 on both ends
You may use the mesh type heater 51 which has.

[0026]

As described above, according to the present invention, when the exhaust flow rate adjusting means of the second and third exhaust passages are both open, the exhaust gas is connected to each of the exhaust passages. The exhaust gas flows into the second and third purification chambers and is almost evenly distributed over the entire area of the trapping member, so that the exhaust particulates can be efficiently trapped, and any of the exhaust flow rate adjusting means provided in the second and third exhaust passages. If one of them is closed and the heating means is operated in this state, the amount of exhaust gas flowing into the purification chamber connected to the passage on the closed side is reduced, so that the heating operation by the heating means in the collecting member is efficient. It is performed well, and the collection member can be regenerated satisfactorily. During this playback,
Most of the exhaust gas passes through one of the exhaust passages and is collected in one of the purification chambers, but the collection member on the collection side is heated by the heat generated by the collection member on the regeneration side. Therefore, the activity of the catalyst supported on the collecting member is improved, and the oxidation reduction performance of SOF in the exhaust particulates is significantly improved, so the overall reduction rate of the exhaust particulates is almost the same as in the non-regenerated state. Can be held at As a result, the collecting member need only be relatively small, and the device itself can be prevented from increasing in size.

Further, by providing the second cleaning chamber heating means and the third cleaning chamber heating means separately at respective portions of the collecting member located in the second cleaning chamber and the third cleaning chamber,
When the exhaust flow rate adjusting means of one exhaust passage is closed at the time of regeneration, only the heating means in the purification chamber connected to this one exhaust passage is operated, so that the collection member is efficiently regenerated without waste. be able to.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of an exhaust emission cleaning device for a diesel engine according to the present invention.

FIG. 2 is a plan sectional view of the embodiment of FIG.

3 is a sectional view taken along the line AA of the embodiment of FIG.

FIG. 4 is a cross-sectional plan view of another embodiment of the exhaust gas purification device for a diesel engine according to the present invention.

FIG. 5 is a plan cross-sectional view of another embodiment of the exhaust purification system for a diesel engine according to the present invention.

6 is a sectional view taken along line BB of the embodiment of FIG.

FIG. 7 is a plan cross-sectional view of another embodiment of the exhaust emission control device for a diesel engine according to the present invention.

FIG. 8 is a configuration diagram of a heater of the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 2nd exhaust passage 3 3rd exhaust passage 5 Filter case (vessel) 7 2nd valve (exhaust flow rate adjusting means) 9 3rd valve (exhaust flow rate adjusting means) 11 Partition wall 13 Partition wall 15 2nd purification chamber 17 3rd purification chamber Reference Signs List 19 first purification chamber 21 first exhaust passage 23a filter (collection member) 23b filter (collection member) 23c filter (collection member) 27 pellet catalyst (catalyst) 29 heater (second purification chamber heating means) 31 heater ( Third purification chamber heating means) 33 Control unit 37 Regeneration control circuit (control means) 45 Ceramic foam filter (collecting member) 51 Mesh type heater (heating means)

Claims (2)

[Claims] 1. A container, which is partitioned by a partition wall into a central first purification chamber and a second purification chamber and a third purification chamber located on both sides of the first purification chamber, wherein A collection member that collects the exhaust particulates in the exhaust when the exhaust gas passes is arranged through the partition wall, and the collection member carries a catalyst and burns and removes the collected exhaust particulates. And a first exhaust gas to the first purification chamber.
While connecting the first exhaust passage leading to the purification chamber, the second and third purification chambers are connected to the second and third exhaust passages for introducing the exhaust gas to the second and third purification chambers. 3. An exhaust gas purification device for a diesel engine, characterized in that exhaust flow rate adjusting means for adjusting the flow rate of exhaust gas in each of the three exhaust passages is provided. 2. A container, which is partitioned by a partition wall into a central first purification chamber and a second purification chamber and a third purification chamber located on both sides of the first purification chamber, wherein A collection member that collects exhaust fine particles in the exhaust gas when the exhaust gas passes is arranged so as to penetrate the partition wall, and the collection member carries a catalyst and is located in the second and third purification chambers. A second purification chamber heating means and a third purification chamber heating means for burning and removing the collected exhaust particulates, respectively, and exhausting the exhaust gas from the first purification chamber to the first purification chamber. The first exhaust passage is connected, while the second and third exhaust passages for introducing exhaust gas into the second and third purification chambers are connected to the second and third purification chambers, and the second and third exhaust passages are connected to the respective exhaust passages. Exhaust flow rate adjusting means for adjusting the flow rate of exhaust gas in the passage is provided, and the second purification chamber heating means is provided. When operating, the exhaust flow rate adjusting means provided in the second exhaust passage is adjusted to reduce the exhaust flow rate, while when operating the third purification chamber heating means, the exhaust flow rate adjusting means provided in the third exhaust passage is adjusted. An exhaust gas purification device for a diesel engine, which is provided with control means for reducing the exhaust gas flow rate.