JP2817588B2 - Filter regeneration device for internal combustion engine - Google Patents

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 a filter for an internal combustion engine for collecting particulates (particulate matter) contained in exhaust gas discharged from a diesel engine by using microwave energy. It is.

[0002]

2. Description of the Related Art A conventional microwave filter regenerating apparatus is disclosed, for example, in JP-A-59-122022. FIG. 5 shows an apparatus disclosed in the publication. 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 containing the filter 5, 7 is microwave generating means, and 8 is microwave generating. A waveguide for guiding the microwave generated by the means 7 to the heating chamber 6, 9 a microwave reflecting plate, 10 an air pump, 11 an air supply path, 12 a driving power source for the microwave generating means 7, 13 a muffler, 14 is an air switching valve, 1
Reference numeral 5 denotes an exhaust gas flow switching valve.

In the above configuration, the exhaust gas of the engine 1 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. If the particulates continue to be collected, the filter 5 will be clogged and the collection capacity will be greatly reduced, and the flow of exhaust gas will be poor, resulting in a decrease in engine output and an engine stop. Therefore, when the trapping capacity of the filter 5 reaches the limit, the exhaust gas flow switching valve 15 is controlled, the exhaust gas flow to the exhaust pipe 3 is cut off, and all the exhaust gas is exhausted to the atmosphere via the exhaust branch pipe 4. During this time, the regeneration of the filter 5 is performed. In this filter regeneration cycle, the energy for heating the particulates is supplied from the microwave generation means 7 and the air required for combustion is supplied from the air pump 10. When the regeneration of the filter 5 is completed after a predetermined time, the exhaust gas flow switching valve 15 is controlled again, and the exhaust gas is guided to the filter 5. This cycle of collection and regeneration is repeated.

[0004]

However, the above-mentioned conventional apparatus has the following problems when the particulates collected by the filter 5 are removed by heating.

[0005] These problems are caused by the burning process of the particulates and by the amount of the particulates collected in the filter and the temperature of the filter and the particulates.

That is, the particulates accumulated in the filter during the regeneration process react with the oxygen in the air supplied by heating by the microwaves and burn. At the start of the regeneration, the particulates are ignited by the energy of the microwaves, but it is difficult to ignite the entire surface of the inlet of the microwaves of the filter. When the combustion is started, the energy of the microwaves, the heat of the combustion, and the supplied air move from the upstream side to the downstream side of the combustion, and the range of the combustion is expanded. At this time, if air is continuously supplied, the combustion expands faster in the longitudinal direction than in the radial direction of the filter, so that the temperature near the center of the filter rises excessively and melts the filter. The temperature difference is so large that the filter causes cracks in the filter, and particulates near the outer periphery cannot be removed by burning.

The amount of particulates accumulated in the filter at the start of regeneration is detected by the differential pressure before and after the filter, the collection time, etc., but depends on the engine speed, exhaust temperature, differential pressure detection capability, and the like. There is a wide range of variation. Also, the temperature of the filter and the collected particulates at the start of regeneration is about 400 ° C. (full load) from near ambient temperature due to the operating state of the engine at the time of completion of collection and the length of time from the end of collection to the start of regeneration. Operating exhaust temperature)
It varies over a very wide temperature range up to a degree. Therefore, if a fixed amount of microwaves and air are supplied during regeneration, the amount of accumulated particulates is large, and if the temperature of the filter and the particulates is high, the heat of particulates is added to the initial heat of the particulates and the filter becomes hot. And mechanical damage such as generation of cracks or erosion is caused.

The present invention solves the above-mentioned problems, and effectively removes particulates trapped in the filter to the vicinity of the outer periphery of the filter, and impairs the function of the filter under a wide range of conditions at the start of reproduction. It is an object of the present invention to provide a filter regeneration device for an internal combustion engine that can be used without any problem.

[0009]

SUMMARY OF THE INVENTION The present invention, in order to achieve the above object, includes a heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, in the exhaust gas is accommodated in the heating chamber A filter for collecting the particulates, microwave generating means for generating a microwave for heating the particulates, and gas supply means for supplying a gas for burning the heated particulates ;
At the time of regeneration for burning and removing the particulates , the gas supply means is continuously operated in the early stage and the later stage of the particulate combustion,
In the middle stage of combustion, control is performed so as to drive intermittently.

Further, the energy of the microwaves supplied from the microwave generating means is supplied more in the early stage of the particulate heating than in the middle stage, and the gas supply means is continuously burned in the early stage and the late stage of the particulate combustion. In the middle period of the above, control is performed so as to drive intermittently.

A storage amount detecting means for detecting the storage amount of particulates in or near the filter;
A drive of at least one of the microwave generation unit and the gas supply unit is controlled based on information from the temperature detection unit for detecting the temperature of the filter, the accumulated amount detection unit and the temperature detection unit.

[0012]

According to the above arrangement, the particulates collected by the filter are heated by the microwave to a temperature at which they can be burned, and first, a continuously supplied gas (for example, air) is supplied.
By oxygen in air) to initiate combustion from the supply side of the gas.
The downstream side of the combustion portion is heated by the heat transfer of the combustion heat and the microwave, and the combustion region gradually moves downstream while keeping the temperature of the combustion portion at a combustible temperature . When the ignition of the particulates is completed and the combustion is substantially stabilized, the gas supply means enters the intermittent drive state. During intermittent drive of gas supply means
In the state where gas is supplied, the combustion area
The area is diffused and moved downstream by the gas flow. On the other hand, in the state where the supply is stopped, the supply of oxygen to the particulates is stopped, so that the combustion is stopped. And the radial cross section of the filter can be made uniform. When the gas is supplied again to the filter which has been uniformly heated in the radial direction, the burning region shifts to the downstream side while burning particulates over almost the entire cross section in the radial direction .
You. Therefore, the temperature difference between the center of the filter and the vicinity of the outer periphery can be suppressed, and the particulates accumulated near the outer periphery of the filter can also be removed by combustion. And
By repeatedly supplying and stopping the gas, when the combustion area reaches the vicinity of the most downstream side of the filter, by continuously driving the gas supply means again, the remaining particulates are rapidly burned, so that the most downstream side of the filter is provided. Particulates can also be burned off.

Further, by supplying a large amount of microwaves to be supplied to the particulates in the early stage of the regeneration, the time required for the particulates to reach the combustible temperature can be shortened, and the combustion range can be expanded to reduce the amount of self-generated heat of the particulates. By reducing the supply amount of microwaves at the time when the number increases, an excessive rise in temperature of the filter can be suppressed.

Further, there is provided a means for detecting the filter temperature and the amount of accumulated particulate at the start of regeneration, and by controlling the driving time of the gas supply means and the microwave supply means based on the information from the means, the filter temperature and the particulate matter are controlled. By setting the gas and microwave supply amounts that are optimal for the amount of curate accumulated, the above effects can be rationally exhibited.

[0015]

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

In FIG. 1, reference numeral 21 denotes an exhaust pipe A for discharging exhaust gas from an internal combustion engine, which is connected to an internal combustion engine (not shown). 22 is a heating chamber provided in the middle of the exhaust pipe, 23 is a filter which is housed in the heating chamber 22 and collects particulates contained in the exhaust gas when the exhaust gas passes therethrough,
24 is a heating chamber 2 for inductively heating the particulates.
2, a microwave generating means for generating microwaves to be supplied into the heating chamber 2, a waveguide 25 for transmitting the microwaves generated by the microwave generating means 24 into the heating chamber 22, and a heating pipe 22 for the heating chamber 22.
A power supply hole for supplying microwaves to the antennas, and 27 and 28 are microwave shielding means constituted by a punching plate or the like for shielding the microwaves. Reference numeral 29 denotes gas supply means for supplying a gas (such as air) containing oxygen to burn the particulates, and reference numeral 30 denotes an exhaust pipe B for discharging exhaust gas to the atmosphere. Reference numeral 31 denotes a valve A, which is controlled so as to be opened at the time of collecting particulates and closed at the time of regeneration. 32 is an exhaust pipe C for discharging combustion exhaust gas during regeneration,
3 is a valve B which is closed when collecting particulates,
At the time of reproduction, it is controlled to open. Reference numeral 34 denotes a control unit that controls operations of the microwave generation unit 24, the gas supply unit 29, the valve A31, and the valve B33.

In FIG. 2, reference numeral 35 denotes a storage amount detecting means provided in the exhaust gas non-flow space of the filter 23 to detect the amount of microwaves existing in the installation space and to determine the storage amount of particulates; Is a temperature detecting means that is in close contact with the wall surface of the filter and performs temperature detection of the filter.

In the above configuration, when collecting particulates, the valve A31 is open and the valve B33 is closed, and the exhaust gas of the internal combustion engine flows through the exhaust pipe 21 into the flow heating chamber 22 in the direction of the arrow. It flows into the filter 23. The filter 23 is formed of a wall flow type honeycomb structure and has a function of collecting particulates contained in exhaust gas. The exhaust gas whose particulates have been collected by the filter 23 is discharged into the atmosphere via the exhaust pipe 30.

At the time of regeneration for burning and removing particulates collected by the filter 23, when a regeneration start command is issued from the control unit 35, the valve A31 is closed, and the valve B33 is closed.
Is released, and the microwave generation means 24 is activated. The generated microwave is supplied into the heating chamber 22 from the power supply hole 26 via the waveguide 25 and heats the particulates collected by the filter 23 (at the time of heating) . The particulates are heated by the microwave to reach a temperature at which combustion is possible, and when the gas supply means 29 is activated, the particulates are shown in FIG. 3 (T1 to T2).
As to initiate combustion than the portion closer to the inflow surface into the gas I by oxygen in the gas supplied by the continuous operation (combustion first
Period) . Some of the combustion heat is transferred to the thermal conductivity or gas micro
With wave energy to heat the sequential downstream heating the downstream combustible temperature. Therefore, the particulate combustion area moves sequentially downstream while expanding. After a lapse of a certain time (mid-combustion), the control unit 34 controls the gas supply unit 2
9 is an intermittent drive operation as shown in FIG. 3 (T2 to T3) . During the intermittent drive, the gas supply means 29 is in the operating state.
When gas is supplied in the same manner as in the continuous operation, oxygen is supplied to the burning part of the particulates, and a part of the combustion heat is transferred to the heat transfer and the gas and the downstream side together with the microwave energy. heated sequentially to heat the downstream combustible temperature.
Gas supply means 29 is a combustion of the particulates are heat is transferred radially heat transfer is suppressed to heat the filter 23 downstream of the combustion unit stops to becomes stopped the supply of oxygen is eliminated. At this time, when the gas supply is stopped, the heat transferred to the downstream side of the filter 23 by the gas is greatly reduced, and the amount of heat transfer in the radial direction is relatively increased, so that the temperature distribution in the radial direction is uniform. It will be close. Then again
When the gas supply means is in the operating state as shown in FIG. 3 (T3 to T4), oxygen is supplied to the particulates which are heated substantially uniformly in the radial direction of the filter 23, and burns from almost the entire surface in the radial direction of the filter 23 to the downstream side. Will migrate. At this time,
Since the filter 23 emits heat from the outer periphery, the vicinity of the outer periphery is lower than the center. If the gas supply means 29 is configured to always operate continuously, the particulates collected in the filter 23 continue to burn, but the vicinity of the outer periphery If microwaves and gas are supplied in such an amount that the particulates accumulated in the filter can be burned, the temperature in the central part rises excessively and causes cracks and melting damage in the filter 23. Also, if a quantity is supplied such that the temperature in the central portion becomes an appropriate temperature, the particulates accumulated in the vicinity of the outer periphery do not burn and remain after regeneration, causing a problem that accumulation is repeated even after repeated collection and regeneration.

The temperature of the particulates is about 800
If the temperature is higher than 0 ° C., the supply of oxygen accelerates the combustion reaction and the temperature rises rapidly.
It is not preferable to lengthen the operating time of. On the other hand, if the operating time is shortened, the combustion time becomes longer, so that the time required for regeneration becomes longer and practical use becomes difficult. According to experiments, the maximum temperature of the filter 23 was maintained at 900 ° C. or less,
Moreover, in order to shorten the time required for regeneration as much as possible, the result obtained was that the operation time of the gas supply means 29 is preferably within one minute. Further, while the gas supply means 29 is stopped, the combustion of the particulates is interrupted, and the heat of the combustion part is transferred to the surroundings, so that the temperature of the combustion part decreases. However, the thermal conductivity of the material constituting the filter 23 is low. The time required for heat transfer becomes longer, and the time for lowering the temperature once increased by the supply of oxygen to the temperature before the increase needs to be longer than the time for supplying gas, that is, the operation time of the gas supply means.

When the intermittent drive period of the gas supply means 29 elapses and the combustion of the particulates reaches near the downstream side of the filter 23, the gas supply means 29 is again in the continuous drive state. On the most downstream side of the filter 23, since the end face of the filter 23 is in an open state, a large amount of heat is radiated by radiation from the same face, so that the temperature decreases and it becomes difficult to burn the particulates. By supplying, the particulates accumulated at the end of the filter 23 can be burned off by continuing the combustion.

Further, since the time to <br/> regeneration completion to take longer when the heating time the amount of particulate accumulated in the filter 23 is often take longer, in this embodiment
In addition as shown in FIG. 4 the microwave energy to play the initial
By increasing the supply amount of the fuel, it is possible to shorten the time required for the particulates to reach a temperature at which the particulates can be burned, and to shorten the time required for regeneration.

FIG. 2 shows another embodiment of the present invention. In FIG. 2, a reference numeral 35 denotes a storage amount detecting means provided in the exhaust gas non-flow space of the filter 23 to detect the amount of microwaves existing in the installation space to determine the storage amount of particulates, and 36 denotes a wall surface of the heating chamber 22. This is a temperature detection unit that performs the temperature detection of the close filter.

The accumulation amount and temperature of putty <br/> Ikyureto in the filter 23 at the time of reproduction start varies depending on the operating conditions of the internal combustion engine mounted. That is, the accumulated amount varies depending on the operating time since the previous regeneration, the engine speed, the operating load, and the like, and the temperature varies depending on the final operating conditions of the internal combustion engine and the idle time from when the operation is stopped to when the regeneration is started. . In the regenerator, the heat source for burning and removing the particulates accumulated in the filter 23 is supplied by the energy of the supplied microwave and the heat generated by the burning of the particulates. Reproduction conditions vary depending on the temperature at the start of reproduction .

Therefore, when the accumulation amount and the temperature are out of the limited range, the particulates may not be burned and removed, or the temperature of the filter may rise excessively. In the present invention, the microwave supply unit 24 is operated by the storage amount detection unit 35, the temperature detection unit 36, and information from them.
By providing the control unit 37 for controlling the driving time of the gas supply means 29, it is possible to expand the usable storage amount and temperature range. The storage amount detecting means 35 provided in the heating chamber 22 detects the amount of microwaves in the space provided. The microwaves generated by the microwave generating means 24 pass through the waveguide 25 and the power supply port 26 to the filter 23. However, since the microwaves have the property of being accumulated in the filter 23 and being absorbed by the particulates, the amount of the microwaves detected by the accumulation amount detecting means 35 is small when the accumulated particulates are large. When the amount of particulates is small, the number of detected particulates is large, and the amount of accumulated particulates can be correlated. Further, the temperature of the filter 23 can be obtained by temperature detecting means 36 provided in close contact with the outer surface of the heating chamber 22. Accumulation detecting means 36 can detect with higher accuracy if it is in direct contact with filter 23, but in the embodiment, it is provided on the outer wall in order to maintain the airtightness of heating chamber 22. After the start of the reproduction, the accumulated amount information and the temperature information obtained by the accumulated amount detecting means 35 and the temperature detecting means 36 are stored in the control unit 3.
7, and drives the microwave generation means 24 and the gas supply means 29 based on preset optimum conditions. At this time, not only the driving time but also the supply amounts of microwaves and gas may be controlled.

[0026]

As described above, according to the filter regeneration device for an internal combustion engine of the present invention, the following effects can be obtained.

(1) Continuous supply of gas at the beginning of combustion
To the particulates accumulated in the filter
In addition to stabilizing the ignition combustion of the filter, the gas is intermittently supplied in the middle of the combustion, so that the temperature of the filter does not rise excessively, so that melting and cracking occur.
Burns and removes particulates to the vicinity of the periphery without
It is possible to supply gas continuously in the later stage of combustion.
Almost completely retarding the more downstream filter of the particulate
It is possible to remove by burning, and the
Ticules can be satisfactorily reproduced from upstream to downstream.

(2) By supplying a large amount of a microwave serving as a heating source of particulates at the beginning of heating , the time required to reach a combustible temperature is shortened, and
When the self-heating value of the heat
By reducing the amount, suppressing excessive Atsushi Nobori of the filter
As well as low self-heating of particulates
Even if it is difficult to maintain the heat required for combustion.
You. Also, the time required for reproduction can be reduced.

(3) The amount of particulates stored in the filter at the initial stage of regeneration and the temperature of the filter are detected, and the supply condition of the particulates in a high range is optimized by optimizing the supply conditions of microwaves and combustion gas. Particulates can be removed within the range of temperature change.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a filter regeneration device for an internal combustion engine according to another embodiment of the present invention.

FIG. 3 is a diagram showing a gas supply state according to an embodiment of the present invention.

FIG. 4 is a diagram showing a supply state of microwaves according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional filter regeneration device for an internal combustion engine.

[Explanation of symbols]

 Reference Signs List 22 heating chamber 23 filter 24 microwave generator 29 gas generator 35 accumulated amount detecting means 36 temperature detecting means 37 controller

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Nobuhiko Fujiwara 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (56) References JP-A-5-202733 (JP, A) JP-A-5-106427 (JP, A) JP-A-4-255518 (JP, A) (58) Fields investigated (Int. . ^6, DB name) F01N 3/02 301 - 341

Claims (4)

(57) [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 heating the particulates Microwave generating means for generating a microwave for performing, and a gas supply means for supplying a gas for burning the heated particulates, and during regeneration for burning and removing the particulates
A filter regeneration apparatus for an internal combustion engine, comprising: a control unit that drives the gas supply means continuously during an early stage and a late stage of the particulate combustion, and intermittently during an intermediate stage of the combustion. 2. A heating chamber provided in an exhaust pipe for exhausting exhaust gas of an internal combustion engine, a filter housed in the heating chamber and collecting particulates contained in the exhaust gas, and heating the particulates. Microwave generating means for generating microwaves for performing the heating, and gas supply means for supplying a gas for burning the heated particulates, and the microwave energy from the microwave generating means is increased in the early stage of heating. Supply and putty
After starting at the time of regeneration for burning and removing the curate, the internal combustion engine is provided with a control unit that drives the gas supply means continuously during the initial combustion and the late combustion of the particulate, and intermittently during the intermediate period of the combustion. Filter regeneration device. 3. A storage amount detection means for detecting the storage amount of particulates provided in or near the filter,
2. A temperature detecting device for detecting a temperature of the filter, and a control unit for controlling driving of the gas supply device based on information from the accumulated amount detecting device and the temperature detecting device.
The filter regeneration device for an internal combustion engine according to the above. 4. A storage amount detection means for detecting the storage amount of particulates provided in or near the filter,
A temperature detection unit for detecting a temperature of the filter; and a control unit for controlling driving of at least one of a microwave generation unit and a gas supply unit based on information from the accumulation amount detection unit and the temperature detection unit. Item 3. A filter regeneration device for an internal combustion engine according to Item 2.