JP2856016B2 - 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. 2 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, 7 is microwave generating means, 8 is microwave generating means. 7 is a waveguide for guiding the generated microwaves to the heating chamber 6, 9 is a microwave reflector, 10 is an air pump,
Reference numeral 11 denotes an air supply path, 12 denotes a drive power source for the microwave generating means 7, 13 denotes a muffler, 14 denotes an air switching valve, and 15 denotes an exhaust gas flow switching valve.

In the above configuration, 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 filtered.
Collected by 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, in the above-mentioned conventional structure, in the process of burning particulates, the particulates start burning from the inflow surface of the combustion air, and the downstream side thereof is transferred by the heat transfer of the combustion heat. Because of the heating, the combustion section is kept at a suitable temperature and a temperature at which combustion is possible. However, as combustion proceeds, near the back surface of the filter (the surface opposite to the combustion air inflow surface), there is a lot of heat radiation due to radiation coming into contact with the space downstream, and the particulates collected in that region are reduced. There was a problem that it could not be removed by burning. For this reason, in the repetition of the collection and regeneration of particulates, the amount of particulates deposited near the end face increases, and in the worst case, the flow of exhaust gas into the filter is hindered, leading to a decrease in engine output. was there. The filter regeneration cycle may start at a relatively high temperature where the filter temperature is sufficiently heated by the exhaust gas of the engine, or may start at a low temperature just after the engine is started. Therefore, when heating under the same conditions, if the filter starts regeneration at a high temperature, the temperature during particulate combustion rises too much and the filter is damaged by thermal stress caused by a temperature gradient generated inside the filter, or if regeneration is started at a low temperature There was a problem that the particulates could not be burned and removed due to insufficient temperature.

The present invention has been made to solve the above-mentioned problems, and effectively removes particulates trapped in a filter to the rear surface, and removes particulates regardless of the temperature of the filter at the start of regeneration. It is an object of the present invention to provide a filter regeneration device for an internal combustion engine that does not impair operation.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, and a heating chamber contained in the heating chamber and contained in the exhaust gas. A filter for collecting particulates to be collected, microwave generating means for generating microwaves for heating the particulates, gas supply means for supplying gas for burning the heated particulates,
A temperature detection unit provided in a gas passage downstream of the filter with respect to the expected flow direction, and after the temperature detection unit detects a maximum temperature, the supply amount of the microwave is reduced to a maximum.
The control unit is provided with a control unit that controls the supply before the high temperature detection .

In addition, a control section is provided which controls only the gas supply means for a certain period of time at the start of regeneration and controls the operation of the microwave generation means based on temperature information detected by the temperature detection means.

[0008]

According to the above-mentioned structure, the particulates collected by the filter are heated to a combustible temperature by the microwave, and combustion is started from the supply surface of the combustion gas by the oxygen in the supplied gas. The downstream side of the combustion part is heated by the heat transfer of the combustion heat, keeping the temperature of the combustion part and maintaining the temperature of the combustion part at a combustible temperature, while gradually moving the combustion region to the downstream side. The temperature detected by the temperature detecting means provided in the gas passage on the downstream side of the filter gradually rises due to the progress of the combustion of the particulates collected in the filter, and the combustion area reaches almost the most downstream surface of the filter. Sometimes the maximum temperature is reached. On the other hand, the temperature near the most downstream side of the filter is radiated by radiation because the surface is open to the space on the downstream side, but the control device reduces the supply amount of the microwave after the temperature detection means detects the maximum temperature. Due to the increase, the temperature decrease near the most downstream surface is small, the flammable temperature of the particulates is maintained, and the particulates near the most downstream surface can also be removed by combustion.

When only the combustion gas is supplied for a certain period of time at the start of regeneration of the filter, the gas is exchanged with the heat of the filter in the filter, and is detected by the temperature detecting means provided in the space downstream of the filter. The temperature has a substantially proportional relationship with the temperature of the filter at the start of regeneration. Therefore, when the temperature detected by the temperature detecting means is high, the temperature of the filter is also high, so that the supply amount of the microwave is small by the control unit, and when the temperature detected by the temperature detecting means is low, the temperature of the filter is low. By supplying a large amount of microwaves, it is possible to appropriately maintain the burning temperature of the particulates, and it is possible to prevent damage to the filter due to overheating and poor regeneration due to insufficient heat.

[0010]

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 for discharging the exhaust gas from which the particulates are collected by the filter 23 to the atmosphere. B. 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. Reference numeral 32 denotes an exhaust pipe C for discharging combustion exhaust gas at the time of regeneration, and 33 denotes a valve B, which is controlled so as to be closed at the time of collecting particulates and open at the time of regeneration. 34 is a temperature detecting means,
During regeneration, the temperature of particulate combustion exhaust gas is detected. 35 is a microwave generation means 24, an air supply means 2
9, a control unit for controlling the operation of the valve A31 and the valve B33.

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. Then, 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 the particulates collected by the filter 23, when a regeneration start command is issued from the control unit 35, the valve A31 is closed, the valve B33 is opened, and the gas supply means 29 is activated. Gas supply means 29
The supplied gas passes through the filter 23 and reaches the inside of the exhaust pipe A21, but the other end of the exhaust pipe A21 is guided to the exhaust pipe C32 and discharged to the atmosphere because the internal combustion engine is stopped and is in a closed state. You. After a certain period of time, the microwave generating means 24 is activated, and 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. I do. When the particulates are heated by the microwaves and reach a temperature at which combustion is possible, combustion starts from a portion near the gas inflow surface by oxygen in the gas supplied from the gas supply means 29.
A part of the heat of combustion is transferred to the heat of conduction or gas to heat the downstream side and sequentially raise the downstream side to a combustible temperature. Therefore, the particulate combustion region sequentially moves downstream while expanding. In the vicinity of the most downstream side, since the surface faces the space, the amount of heat radiation due to radiation is large, the temperature of the particulate decreases greatly, and the particulates in the vicinity remain due to the combustion failure due to the combustion failure temperature range The phenomenon is easy to occur. If the particulates remain after the regeneration, the accumulation of the particulates increases while the collection and the regeneration are repeated, and the resistance causes a problem such as a decrease in the output of the engine. In order to suppress the residual particulates, there is a means for supplying an extra amount of microwave from the beginning by the amount of heat radiation by radiation. However, in this case, the temperature rises more than necessary in the middle of the combustion process, and the melting of the filter 23 occurs. There is a problem that damage due to loss or thermal stress is caused.

The gist of the present invention is that the combustion state of the particulates is detected by the temperature detecting means 34 provided at the downstream side of the path of the combustion exhaust gas. The amount of supply is increased to promote the burning of the particulates in the part. That is, the temperature detected by the temperature detecting means 34 provided on the downstream side of the particulate combustion flue gas path rises according to the expansion of the combustion area and the downstream movement after the start of particulate combustion. When the combustion area reaches the vicinity of the most downstream of the filter 23, the temperature decreases because the fuel area becomes smaller. Therefore, when the detecting means 34 detects the maximum temperature of the flue gas, it can be determined that the combustion area has reached the vicinity of the most downstream side of the filter 23. Therefore, even if the supply amount of the microwave is increased, the combustion area does not become overheated, and Can be compensated for, and the particulates in the vicinity of the most downstream can be maintained at the combustible temperature, and the residual particulate due to poor combustion can be prevented.

Further, in order to enable the reproducing operation at any time, it is necessary to relax the conditions at the time of reproducing. One of the conditions during regeneration is the temperature of the filter 23. Filter 2
The temperature of No. 3 is high when the regeneration is started immediately after the engine is stopped, and is low when the regeneration is started immediately after the engine is started. When reproduced under the same microwave supply conditions, the filter 23
When the temperature of the filter 23 is high, the temperature of the filter 23 is heated more than
If the temperature is low, poor combustion may occur due to insufficient temperature, and particulates cannot be removed.

According to the present invention, only the gas supply means 29 is operated for a certain time at the start of regeneration, the supplied gas exchanges heat in the filter 23, and the temperature is detected by the temperature detection means 34 on the downstream side. Thus, the initial temperature of the filter 23 can be detected, and when the temperature of the filter 23 is high, the supply amount of the microwave is reduced, and when the temperature is low, the supply amount of the microwave can be increased. Therefore, it is possible to prevent a failure due to overheating of the filter 23 at a high temperature and a defective combustion of particulates at a low temperature.

[0017]

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) A temperature detecting means is provided in a space on the downstream side of the filter to detect the temperature of the combustion exhaust gas to control the supply amount of the microwave, so that the filter is not abnormally overheated and the vicinity of the most downstream side of the combustion is prevented. Can be almost completely removed.

(2) By operating only the gas supply means for a certain period of time at the start of regeneration, detecting the gas temperature and controlling the amount of microwave supply, particulates can be removed regardless of the initial filter temperature. .

[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 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 supply device 34 temperature detection means 35 control unit

Continuation of the front page (72) Inventor Toshitaka Nobue 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-121415 (JP, A) JP-A-3-210012 ( JP, A) JP-A-4-136409 (JP, A) JP-A-4-353208 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01N 3/02 321

Claims (2)

(57) [Claims] 1. A heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, a filter housed in the heating chamber and collecting particulates contained in the exhaust gas, and the particulate matter. Microwave generating means for generating microwaves for heating the gas, and heated particulates
Gas supply means for supplying gas for burning the gas, temperature detection means provided in a gas passage downstream of the filter with respect to the flow direction of the gas, and after the temperature detection means detects a maximum temperature, Maximum temperature of microwave supply
A filter regeneration device for an internal combustion engine, comprising a control unit for controlling the supply amount to be larger than a supply amount before detection . 2. A heating chamber provided in an exhaust pipe for exhausting exhaust gas of an internal combustion engine, and a filter housed in the heating chamber and collecting particulates contained in the exhaust gas.
When the Patikyure - a microwave generator for generating microwaves to heat the door, heated Patikyure -
Gas supply means for supplying gas for burning the gas, temperature detection means provided in a gas passage downstream of the filter with respect to the flow direction of the gas, and only the gas supply means for a certain period of time at the start of regeneration , A filter regeneration device for an internal combustion engine, comprising: a control unit that controls an operation of the microwave generation unit based on temperature information detected by the temperature detection unit.