JPH06212945A - Filter reprocessing apparatus for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a filter reprocessing apparatus for catching particulates in exhaust gas from a diesel engine which heats and reprocesses the filter while a temperature of the filter being reprocessed for the particulates is low. CONSTITUTION:A filter reprocessing apparatus comprises a heating chamber 18 provided in an exhaust pipe 17 for discharging exhaust gas of an internal combustion engine 16, a filter 19 received in the heating chamber 18 to catch particulates contained in the exhaust gas, a micro-wave generating means 20 to generate the microwave for electrifying the heating chamber, an opening part 23 opened while the microwave generating means 20 is operated and communicating to the heating chamber to be opened and closed and a an exhaust bypass pipe 27 to bypass the exhaust gas from the exhaust pipe 17. The particulates caught by the filter 19 are reprocessed and burnt by utilizing the permeation of the microwave and gently burnt by air supplied through natural convection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for regenerating an internal combustion engine filter for collecting particulates (particulate matter) contained in exhaust gas discharged from a diesel engine by utilizing microwave energy. Is.

[0002]

2. Description of the Related Art With respect to global environmental protection, measures against global warming, that is, CO ₂ reduction measures have been greatly emphasized today, but measures against acid rain causing deforestation cannot be ignored.

Acid rain is a natural phenomenon in which air pollutants such as sulfur oxides and nitrogen oxides are sources of pollution. In recent years, emission regulations of such air pollutants have become common in countries around the world.
There are moves to strengthen fixed sources such as generation and mobile sources such as automobiles. In particular, regulations on exhaust gas from automobiles are shifting from the conventional concentration regulations to total amount regulations, and the regulation values themselves are about to be significantly reduced.

Among automobiles, diesel vehicles are subject to stricter emission control of particulates as well as nitrogen oxides. It is not possible to achieve the exhaust gas regulation value only by conventional measures for reducing pollutants in exhaust gas by improving combustion such as delay of fuel injection timing, and at present it is indispensable to attach an exhaust gas aftertreatment device. This post-treatment device has a filter for collecting particulates.

However, if the particulates continue to be collected, the filter will be clogged, the collecting ability will be greatly reduced, and the flow of exhaust gas will be deteriorated, resulting in a decrease in engine output or engine stop.

Therefore, at present, technical development for regenerating the trapping ability of the filter is being promoted all over the world, but it is not yet practically used.

It is known that particulates burn from about 600 ° C. As a means for generating energy to raise the particulates to this high temperature range,
A burner method, an electric heater method, a microwave method, etc. are considered.

The inventors of the present invention have developed a microwave filter regeneration device in consideration of good temperature rising efficiency, safety, easy device configuration, good regeneration controllability, and the like.

[0009] As a filter reproducing device using a microwave system, there is, for example, Japanese Patent Laid-Open No. 59-126022. The apparatus disclosed in the publication is shown in FIG. In the figure, 1 is an engine, 2 is an exhaust manifold, 3 is an exhaust pipe, 4 is an exhaust branch pipe, 5 is a filter, 6 is a heating chamber accommodating a filter, 7 is microwave generation means, and 8 is microwave generation means. A waveguide that guides the microwave generated by 7 to the heating chamber 6, 9 is a microwave reflection plate, 10 is an air pump, and 1
1 is an air supply path, 12 is a drive power source for the microwave generation means 7, 13 is a muffler, 14 is an air switching valve, and 15 is an exhaust gas flow switching valve.

In the above structure, the exhaust gas of the engine is guided to the filter 5 by the exhaust gas flow switching valve 15 or directly discharged to the atmosphere. In the particulate collection cycle, the exhaust gas is guided to the filter 5 and the particulates contained in the exhaust gas are collected by the filter 5, but the collection capacity of the filter 5 is finite as described above. When the collection capacity reaches the limit, the exhaust gas flow switching valve 15 is controlled so that the exhaust gas to the exhaust pipe 3 is shut off and all the exhaust gas is discharged to the atmosphere via the exhaust branch pipe 4. During this time, the filter 5 is regenerated. In this filter regeneration cycle, the energy for heating the particulates is supplied from the microwave generating means 7 and the air required for combustion is supplied from the air pump 10 at the same time. When the filter regeneration is completed after a predetermined time, the exhaust gas flow switching valve 15 is controlled again to guide the exhaust gas to the filter 5. This cycle of collection and regeneration is repeated.

[0011]

However, in the above-mentioned conventional structure, the combustion control when the particulates are heated and regenerated is performed by adjusting the amount of air from the air pump. At this time, it is difficult to control the combustion because the heat of combustion of particulates propagates to the downstream side of the filter by the air from the air pump, and excessive rapid combustion that occurs partially inside the filter causes the filter to become hot and melt down or There was a problem that cracks occurred.

The present invention solves the above problems and provides a highly reliable filter regenerating apparatus for an internal combustion engine by selectively heating particulates with microwaves to prevent the filter from reaching a high temperature. It is intended for.

[0013]

In order to achieve the above object, the present invention includes a heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, and contained in the exhaust gas contained in the heating chamber. A filter that collects particulates,
The microwave generating means for generating microwaves and the opening portion communicating with the heating chamber which can be opened and closed during operation of the microwave generating means are provided.

[0014]

According to the present invention, with the above structure, the particulates trapped in the filter are selectively heated by microwaves,
Air is supplied to the heated particulates by natural convection, and the particulates that have reached the combustible temperature are sequentially burned, so that the temperature of the filter is prevented from becoming too high.

Further, since the microwave is not supplied to the part where the particulate is not burned and regenerated, the heat is supplied only to the part where the particulate is present, so that the combustion control becomes easy.

[0016]

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

In FIG. 1, 16 is an internal combustion engine, 17 is an exhaust pipe for discharging the exhaust gas from the internal combustion engine 16, 18 is a heating chamber provided in the middle of the exhaust pipe, 19 is the heating chamber, and the exhaust gas is A filter for collecting particulates contained in the exhaust gas while passing, a magnetron 20 which is a microwave generating means for generating microwaves for supplying power to the heating chamber 18, and a microwave 21 generated by the microwave generating means. To the heating chamber 18, 22 is a power supply hole provided on the wall surface of the heating chamber 18 for radiating microwaves to the heating chamber 18, 23 is an openable / closable opening through which gas for combustion flows, 24, Reference numeral 25 is a radio wave shielding means having a microwave shielding function for preventing leakage of microwaves to the outside of the heating chamber 18, and 26 is provided on the outer circumference of the filter 19
A heat insulating material for supporting 9 in the heating chamber 18, 27 is an exhaust bypass pipe for flowing exhaust gas during filter regeneration, and 28 is an air flow path switching valve.

The exhaust gas of the internal combustion engine flows in the direction shown by the arrow in the figure. When passing through the filter 19, particulates contained in the exhaust gas are collected. When the exhaust gas is being conducted to the filter 19, the air flow path switching valve 28 is kept in the state shown by the solid line in the figure to prevent it from leaking to the outside of the exhaust pipe.

When the particulate collection amount of the filter 19 reaches a predetermined amount, the air flow path switching valve 28 is switched to stop the exhaust gas flow to the filter 19 and the exhaust gas of the internal combustion engine 16 is exhausted. The exhaust gas is discharged through a muffler 29 provided on an exhaust bypass pipe 27 attached to the pipe 17. After that, the filter 19 is heated and regenerated by the microwave.

Next, the process of filter regeneration will be described.
The amount of the particulate matter collected by the filter 19 depends on the pressure loss level of the filter 19, the operating time of the internal combustion engine 16, the traveling distance of the vehicle if the internal combustion engine 16 is mounted in the vehicle, or the microwave or light. The filter regeneration process is started when the collected amount reaches the collected amount region where the filter regeneration is to be performed, which is appropriately detected based on the signal from the used detection sensor.

This reproduction control command is issued from the control unit, which is a component of this apparatus. Based on the command from the control unit, the microwave generator 20 is supplied with power for driving it. As a result, the microwave is supplied to the heating chamber 18 accommodating the filter 19 to heat the collected particulates. At this time, the opening 23 is opened and serves as a passage for the air for combustion. Since the microwaves are largely absorbed by the particulates (a) near the power supply holes 22, the temperature rise near (a) becomes large at the initial stage of heating. The particulates start burning when the temperature rises above about 600 ° C.

Therefore, in this embodiment, the particulates in the vicinity of (a) burn first. At this time, the air required for combustion flows in from the exhaust pipe 17 and escapes into the opening 23.
When the combustion regeneration of the portion (a) is completed in this manner, subsequently, the portion (b) where the particulates remain is heated by the microwave. In this way, the particulates of the filter 19 are regenerated and burned from the portion exceeding the temperature at which combustion is possible in sequence. The combustion heat generated at that time hardly propagates to other parts of the filter 19 and the supply of oxygen for combustion is small, so that the filter 19 can be prevented from being damaged by the high temperature due to the combustion heat.

The exhaust gas flowing through the filter 19 is almost completely cut off during the microwave power feeding. When microwave heating progresses and a predetermined time passes, (the predetermined time at this time is the optimum time depending on the amount of microwave energy supplied to the heating chamber, the predetermined particulate collection amount region, etc. It is set.) Burning of particulates is completed.

When the particulates start to burn due to microwave heating, the oxygen in the heating chamber in that portion gradually thins, so that the combustion is controlled and saturated at an appropriate temperature. The behavior of each region promotes uniform combustion.
Uniform combustion can prevent the generation of cracks in the filter 19 and guarantees filter durability performance.

Oxygen required for burning particulates is supplied from the exhaust port 30 to the filter 19 and flows into the opening 23 provided on the opposite side. The opening 23 is directed upward in order to improve the air flow, and has a structure that does not hinder the rising flow of the regenerated combustion air. The gas flow promotes combustion when the temperature of the heated particulates is in the particulate combustible temperature range, but is not such a flow rate as to expand the particulate combustion region in the direction of the gas flow. Since the heat generated by this combustion depends on the soot density, it does not reach an unnecessarily high temperature and the combustion temperature of the filter 19 is suppressed. This state continues until the regeneration of the filter is completed.

Thereafter, the operation of the microwave generating means is stopped after an appropriate time has elapsed. The stop timing may be controlled by a predetermined time that is determined in advance, but by measuring the temperature of the filter, more efficient regeneration control becomes possible. The temperature detecting means 31 shown in FIG. 1 measures the temperature of the wall surface of the portion (c) of the filter 19. Temperature detecting means 3
1, a thermocouple or a thermistor that shields microwaves is used. Since the temperature of the wall surface of the filter 19 correlates with the internal temperature, it can be determined that the combustion regeneration has ended when the temperature of the part (c) of the filter 19 once rises below a predetermined value, and the operation of the microwave generation means 20. Stop.

It is also possible to use other means for detecting the degree of regeneration in determining the predetermined time, such as detection of combustion exhaust heat temperature downstream of the filter, detection of filter pressure loss and the like.

When the filter regeneration is completed by the above regeneration control process, the air flow path switching means is controlled to the initial state. The exhaust gas can then flow into the now regenerated filter.

FIG. 2 shows the temperature characteristics of each part of the filter.
The temperature characteristic of each part of the filter of the filter regeneration device of the present invention is shown by a solid line, and the temperature characteristic of the conventional device is shown by a broken line. As shown in FIG. 2, according to the present invention, since the maximum temperature of the filter can be controlled to be low, the durability of the filter can be increased.

In the conventional example, since the combustion speed depends on the capacity of the blower pump, the control device becomes complicated and the peak temperature Tp is high. With the configuration of the present invention, the peak temperature Tp can be obtained by a simple configuration in which a passage for combustion air is provided.
Get smaller.

Further, the end of regeneration can be detected by detecting the temperature of the portion (c) of the filter. As shown in FIG. 2, at the time point t1 when the regenerative combustion ends, the temperature of the filter falls below the predetermined value T1. This predetermined value is about 400 degrees, which is the temperature at which particulates do not burn. In order to detect this temperature, the temperature detecting means 3 is provided on the wall surface of the filter.
1 is provided.

[0032]

As described above, according to the filter regenerating apparatus for an internal combustion engine of the present invention, the following effects can be obtained. (1) Since the particulates in the filter are selectively heated and burned by the microwave power feeding, the filter regeneration combustion temperature can be suppressed. (2) Since the heat energy for heating and burning the filter is supplied and transmitted only by microwaves without using blast, only the portion where particulates are present is heated,
The filter regeneration is stable regardless of the particulate collection state. (3) No need for a pump or fan for supplying combustion air,
It is possible to simplify the device configuration.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a filter regeneration device for an internal combustion engine showing an embodiment of the present invention.

[Fig. 2] Temperature rise characteristics of filter

FIG. 3 is a configuration diagram of a conventional filter regeneration device for an internal combustion engine.

[Explanation of symbols]

 17 Exhaust Pipe 18 Heating Chamber 19 Filter 20 Microwave Generation Means 27 Exhaust Bypass Pipe 23 Opening 31 Temperature Detection Means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuyuki Motozuka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Toshiro Ogino 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A heating chamber provided in an exhaust pipe for exhausting exhaust gas of an internal combustion engine, a filter housed in the heating chamber for collecting particulates contained in the exhaust gas, and power supply to the heating chamber. Microwave generating means for generating a microwave, and an opening communicating with the heating chamber that can be opened / closed during operation of the microwave generating means,
A filter regeneration device for an internal combustion engine, comprising: a bypass pipe that bypasses exhaust gas from the exhaust pipe. 2. The filter regenerating apparatus for an internal combustion engine according to claim 1, wherein the opening communicating with the heating chamber is provided upward. 3. The filter regenerating apparatus for an internal combustion engine according to claim 1, further comprising temperature detecting means for measuring a wall surface temperature of the filter for collecting particulates.