JPH0783022A - Filter regenerating device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable the heating regeneration at a filter while suppressing a burning temperature of the filter by detecting a physical rate of particulates through electric power rate received by an antenna which detects high frequency, and correcting the detection rate through exhaust gas temperature information. CONSTITUTION:An exhaust pipe 17 is provided for discharging exhaust gas of an internal combustion engine 16, while a filter 19 is housed in the exhaust pipe 17 for capturing particulates included in the exhaust gas. A heating chamber 18 houses the filter 19 for heating and burning the particulates. An antenna 29 is provided on the heating chamber 18 for detecting high frequency in the heating chamber 18. A blowing means 22 feeds assistant gas for burning the particulates to the filter 19. A control part 31 controls operation of a high-frequency generation means and the blowing means 22 based on signals detected by the autenna 29 and information from a filter temperature measuring means. High-frequency power and assistant gas are fed according to a rate of the particulates for controlling regeneration. It is thus possible to improve safety and durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for regenerating a filter for an internal combustion engine, which collects particulate matter (particulate matter) contained in exhaust gas discharged from a diesel engine, by utilizing high frequency energy. is there.

[0002]

2. Description of the Related Art Acid rain, which causes deforestation, has become a serious problem for global environmental protection. Acid rain is a natural phenomenon caused by air pollutants such as sulfur oxides and nitrogen oxides as pollutants. In recent years, emission control of such air pollutants in countries around the world has been fixed sources such as co-generation and automobiles. There is a move to be strengthened against mobile sources such as. 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 under stricter regulations on emission of particulates at the same time as nitrogen oxides. It is not possible to suppress the amount of particulate generation below the exhaust gas regulation value only by conventional measures to reduce pollutants in exhaust gas by improving combustion of the internal combustion engine itself such as delay of fuel injection timing. Post-processing equipment is indispensable. This post-treatment device has a filter for physically collecting particulates.

However, if the particulates continue to be collected, the filter will be clogged, the collecting ability will be greatly reduced, and the exhaust gas flow will be deteriorated, resulting in a reduction in engine output or an engine stop.
In order to solve this, technical development for regenerating the collection ability of the filter is currently underway.

It is known that particulates burn from about 600 ° C. As a method of generating energy for raising the particulates to this temperature,
A burner method, an electric heater method, a microwave method, etc. are considered. The inventors of the present invention have good temperature raising efficiency,
We have developed a microwave filter regeneration device in consideration of safety and good regeneration controllability.

[0006] As a filter reproducing device using a microwave system, there is, for example, Japanese Patent Application Laid-Open No. 59-126022. The device disclosed in this 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 the filter 5, 7 is a high-frequency generator, and 8 is a high-frequency generator 7. A waveguide that guides the microwave generated by the
Reference numeral 9 is a microwave reflection plate, 10 is an air pump, 11 is an air supply path, 12 is a drive power source for the high frequency generator 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 trapping cycle, the exhaust gas is guided to the filter 5 and the particulates contained in the exhaust gas are trapped by the filter 5, but the trapping 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. The energy for heating the particulates in this filter regeneration cycle is supplied from the high-frequency generator 7 and the air required for combustion is simultaneously supplied from the air pump 10. When the filter regeneration is completed after a predetermined time, the exhaust gas flow switching valve 1
5 is controlled again and the exhaust gas is guided to the filter 5.
This cycle of collection and regeneration is repeated.

[0008]

However, in the above-mentioned conventional structure, when the particulate matter trapped in the filter is burned and regenerated, when a high frequency or a combustion-assisting gas is supplied in the same manner, the particulate matter trapped weight causes There is a problem that the combustion state is different. That is, if the amount of particulate matter to be heated is small, the generated combustion heat is small and therefore the combustion is mild, and if the amount of particulate is large, the combustion becomes violent. On the other hand, the practical heat resistance temperature of the particulate collection filter currently developed is about 1000 ° C. at the maximum. When regenerating and burning particulates, it is necessary not to exceed the heat resistant temperature.Therefore, when the amount of particulates collected is large, it is necessary to burn while suppressing combustion by reducing auxiliary combustion air. is there.

Therefore, it is indispensable to detect the collected amount of particulates and carry out the combustion control corresponding thereto in order to improve the reliability of the apparatus.

An object of the present invention is to solve the above problems, and an object thereof is to realize an exhaust gas purifying apparatus equipped with a high-frequency heating means for detecting and heating the amount of particulates trapped.

[0011]

In order to achieve the above object, the high frequency heating apparatus of the present invention has the following configuration.

That is, an exhaust pipe for discharging exhaust gas from an internal combustion engine, a filter for accommodating particulates contained in the exhaust gas contained in the exhaust pipe, a filter for accommodating the filter and heating and burning the particulates. A heating chamber for causing, a high frequency generator for generating a high frequency for heating the particulate, an antenna provided in the heating chamber for detecting a high frequency in the heating chamber, and an auxiliary combustion gas for burning the particulate. A blower for supplying the filter, a filter temperature measuring means for the filter, and a controller for controlling the operation of the high frequency generator and the blower based on the detection signal from the antenna and the information from the filter temperature measuring means. It is configured to have.

Further, an exhaust pipe for discharging exhaust gas of the internal combustion engine, a filter for accommodating particulates contained in the exhaust gas contained in the exhaust pipe, a filter for accommodating the filter and heating and burning the particulates. A heating chamber for causing, a high frequency generator for generating a high frequency for heating the particulate, an antenna provided in the heating chamber for detecting a high frequency in the heating chamber, and an auxiliary combustion gas for burning the particulate. An air supply means for supplying to a filter, an exhaust gas temperature measuring means for measuring the temperature of the exhaust gas, an operation of the high frequency generator and the air blowing means based on a detection signal from the antenna and information from the exhaust gas temperature measuring means. It has the structure which has the control part which controls.

Further, the exhaust gas temperature measuring means is provided outside the heating chamber and in the vicinity of the exhaust gas discharge portion of the heating chamber which houses the filter.

Further, the exhaust gas temperature measuring means is provided on both the upstream side and the downstream side of the exhaust gas in the heating chamber, and when the temperature of the upstream side exhaust gas temperature measuring means and the temperature of the downstream side exhaust gas temperature measuring means become substantially the same, heating is performed. The control unit controls the high-frequency generator and the blowing unit based on the detection signal of the antenna for detecting the high frequency of the room and the information of the exhaust gas temperature measuring unit.

Further, the antenna is composed of a central conductor of a coaxial line and is provided on a wall surface for housing and covering the filter.

[0017]

The present invention has the following functions due to the above structure.

The filter regeneration device for an internal combustion engine of the present invention is
The antenna provided in the heating chamber receives a part of the electric field generated by the high frequency generated from the magnetron. Then, the electric field strength generated in the antenna changes depending on the amount of particulates collected by the filter. The reason is that the distribution of the electric field strength in the heating chamber changes with the cycle of the high frequency wavelength, and the high frequency wavelength varies depending on the dielectric constant of the substance in the electric field. This is because the absolute amount of the high frequency reaching the antenna changes because it is absorbed. That is,
When the amount of particulates in the heating chamber changes, the equivalent dielectric constant changes in the filter portion of the heating chamber, the electric field strength in the heating chamber changes, and the electric field received by the antenna also changes.

By doing so, the trapped amount of particulates can be detected, but the high frequency absorption state of the particulates and the filter itself changes with temperature. That is, since the dielectric loss of ceramic materials tends to increase at high temperatures, the electric field strength generated in the antenna decreases at high temperatures, and exhibits high frequency characteristics as if the amount of particulates were large. Therefore, in order to detect the amount of collected particulates by measuring the electric field strength of the heating chamber, it is necessary to correct the electric field strength generated in the antenna by the temperature of the filter. Since the temperature of the filter when collecting particulates in the exhaust gas is almost the same as the exhaust gas temperature, the present invention estimates the filter temperature by providing the exhaust gas temperature measuring means and measuring the exhaust gas temperature.

For measuring the exhaust gas temperature, a thermocouple or a thermistor, which has a large characteristic change depending on the temperature, is used. However, these electric components cannot be used in a heating chamber where a high frequency electric field is large. Therefore, by providing the exhaust gas temperature measuring means in the vicinity of the heating chamber downstream of the exhaust gas, the exhaust gas temperature can be measured. The exhaust gas temperature downstream of the filter is the exhaust gas that has passed through the filter, so
It is closer to the filter temperature.

Further, the exhaust gas temperature measuring means is provided both upstream and downstream of the filter, and when the temperatures of both of the exhaust gas measuring means become substantially the same, the temperature is judged to be the temperature of the filter. It can detect the accurate filter temperature, correct the information of the amount of particulates by the antenna, and increase the detection accuracy of the amount of traps.
Optimal filter regeneration control can be performed.

[0022]

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

The first embodiment is shown in FIG. In FIG. 1, 16 is an engine, 17 is an exhaust pipe that discharges exhaust gas of an internal combustion engine, 18 is a heating chamber provided in the middle of the exhaust pipe 17, and 19 is housed in the heating chamber and exhausted while the exhaust gas passes through. A filter for collecting particulates contained in the gas, a magnetron 20 as a high-frequency generator for supplying power to the heating chamber 18, a waveguide 21 for transmitting the high frequency generated by the magnetron 20 to the heating chamber 18, and a heater 22 for heating. Room 1
8 is a blower means for supplying an auxiliary combustion gas. This gas is introduced into the heating chamber 18 by opening the open / close valve 23. Reference numeral 24 denotes an exhaust gas branch pipe, and an exhaust path including the filter 19 or the exhaust branch pipe 24 is selected by the valve 25 as an exhaust path of the exhaust gas flow. Reference numerals 26 and 27 denote high-frequency shielding means that limit the heating chamber 18, and have a punching hole structure. Reference numeral 28 denotes a filter holding material provided between the outer periphery of the filter 19 and the inner wall of the heating chamber, which also has a heat insulating function.

The exhaust gas flows in the exhaust pipe from the direction indicated by the arrow a in the figure and flows into the filter 19. Filter 19
Is composed of a wall flow type honeycomb structure,
It has a function of collecting particulates contained in the exhaust gas. When the amount of particulates collected by the filter 19 increases, the pressure loss of the filter 19 increases, the load of the engine 16 which is an internal combustion engine increases, and in the worst case, the engine stops. Therefore,
When a predetermined particulate is collected in the filter 19, the filter 19 needs to be regenerated.

Magnetron 20 as a high frequency generator
The radio wave emitted from the electromagnetic wave is transmitted through the waveguide 21, is distributed as a standing wave determined by its shape in the heating chamber 18, and heats the particulates collected by the filter 19.
The heating distribution of particulates is determined by the distribution of radio waves.

The weight of the particulates depends on the filter 18
It is detected by the antenna 29 provided on the side surface of the. That is, the electric field of the standing wave generated by the wave that is not absorbed and reflected when the particulate is heated and regenerated by the microwave as in the present invention is detected by the antenna 29, and the detection signal changes depending on the amount of the particulate. Use this to estimate the amount of particulates. The amount of high-frequency electric field detected by the antenna changes with temperature. That is, the permittivity and the dielectric loss of the filter portion 19 including the collected particulates have temperature characteristics, and the permittivity is larger and the dielectric loss is higher at higher temperatures. This is because the material used for the filter has the property of a ceramic material such as cordierite or mullite. Therefore, the temperature of the filter is estimated by detecting the temperature of the exhaust gas using the exhaust gas temperature detecting means 30. Since the exhaust gas temperature detecting means 30 is used to estimate the temperature of the filter 19, it serves as the filter temperature detecting means 30a. The exhaust gas temperature detecting means 30 uses a sheathed thermocouple covered with stainless steel so as not to be corroded by a sulfide-based component mixed in the exhaust gas. As the temperature detecting element, a thermocouple or other element having a large temperature characteristic may be used depending on the detected temperature range and accuracy.

The control section 31 determines the particulate weight by the exhaust gas temperature measuring means 30 based on the signal from the antenna 29, and outputs a signal for supplying the high frequency generator 20 or the combustion gas in accordance with the particulate weight.

Reference numeral 32 is a muffler for silencing. When the exhaust gas flows through the filter 19 and is collected, the device itself functions as a muffler.

FIG. 2 shows a detailed view of the antenna 29 section. A detection hole 33 for detecting a high frequency with the antenna 29 is provided on the wall surface of the heating chamber 18, and a semi-rigid coaxial cable 34 is inserted therein. The center conductor of the coaxial cable 34 is configured to project longer than the surrounding conductor, and this serves as an antenna. The present embodiment is configured to detect the high frequency electric field strength. As the insulator 35 of the coaxial cable, a fluororesin having good high frequency characteristics and relatively high heat resistance is used.

FIG. 3 shows an example of the particulate collection amount and the antenna detection amount. With the configuration of Fig. 1, a 2.5L filter is installed in a heating chamber of about 6L, and a 2450MHz 400
Supply high frequency of W. Antenna length 3 in the configuration of FIG.
It is a characteristic when 6 is set to 5 mm. As shown in FIG. 3, the collection amount can be detected by correcting the collection amount of particulates by the temperature measuring device. For example, when the temperature of the exhaust gas is 300 degrees and the output of the antenna is 5 mW, it is possible to estimate the trap amount of the filter as 7 g / L. The temperature of the exhaust gas can be roughly estimated by the engine speed of the internal combustion engine and its load, but without the exhaust gas temperature measuring means, the detection accuracy of the trapped amount is significantly lowered as can be seen from FIG.

In FIG. 1 and FIG. 2, the control unit 31 supplies the optimum high frequency electric energy for each particulate weight to the particulates of the filter 19 according to a pre-stored control procedure, and then the combustion assisting means. To supply the supporting gas. Therefore, the particulates can always be efficiently heated.

The timing of the combustion regeneration of the collected particulates may be any time as long as the collected amount is not less than a predetermined value and the back pressure of the exhaust pipe does not increase to damage the engine. However, for example, in a mobile vehicle, if the battery is not sufficiently charged, the engine is stopped, or the like, and sufficient heating energy for regeneration cannot be supplied, regeneration cannot be performed. Moreover, the amount of particulates generated per unit time greatly varies depending on the engine speed, the load, and the nature of the heated fuel. For this reason, the amount collected during regeneration is not always constant. Therefore,
When the regeneration conditions are satisfied, optimum high-frequency power supply and optimum supply of the combustion-enhancing gas are performed according to the amount of each trap.

Next, the basic process of reproducing the filter 19 will be described. When the amount of collected particulates reaches the state of executing the filter regeneration, the filter regeneration is started. This reproduction control command is issued from the control unit 31, which is a constituent element of this device. The regeneration start command is the integral of the operating time of the engine, the pressure difference before and after the filter 19, the temperature of the filter 19, or the antenna 29 and the exhaust gas temperature measuring means 30 obtained by periodically operating the magnetron 20 for a short time. The signal is internally processed by the arithmetic unit of the control unit 31 to determine the reproduction executable state and the reproduction control algorithm.
First, the valve 25 is switched based on the command from the control unit 31. As a result, the exhaust gas is guided to the exhaust branch pipe 24. Next, driving power is supplied to the magnetron 20. Microwaves from the magnetron 20 are transmitted through the waveguide 21 and fed into the heating chamber 18. At this time, as described above, the control unit 31 determines the heating amount by the high frequency according to the amount of particulates. After an appropriate time has elapsed, the particulates present on the exhaust gas downstream side of the filter 19 reach the combustible temperature. At this time, the exhaust gas flowing through the filter 19 is almost completely cut off. As a result, the temperature of the particulate heated by the microwave efficiently rises toward the combustible temperature range.

Thereafter, the valve 23 is controlled so that a gas containing oxygen at an appropriate flow rate is supplied to the filter 19 by the air blower 22 as an auxiliary gas. The supply amount of this gas also differs depending on the particulate collection amount. In this way, the particulates in the filter 19 start to burn, and the particulates in almost the entire area of the filter 19 are burned and removed after an appropriate time according to the amount of particulates collected.

The operation of the magnetron 20 does not need to be continued until the particulate combustion in the entire area of the filter 19 is completed, and after the particulates present on the exhaust gas downstream side of the filter 19 are changed to the combustion state, it is appropriate time. It can be stopped or the microwave power can be reduced.

When the filter regeneration cycle is completed, the valve 23 is returned to its original state. After that, the valve 25 is controlled, the exhaust gas is caused to flow into the filter 19, and particulate collection is performed.

Efficient heating of the particulates according to the amount of trapped particles makes it possible to increase the efficiency of the internal combustion engine filter regenerator.

Further, as shown in FIG. 2, the antenna 29 is a filter holding material 28 provided around the filter 19.
Has a structure covered by. This holding material 2
8 has a heat insulating function and a buffering function, and has a filter 19
The antenna 29 for detection is also protected.

As shown in FIG. 3, when the exhaust gas temperature reaches about 480 degrees, the output from the antenna 29 almost disappears. This is because the dielectric loss of the filter 19 becomes large. Therefore, when the exhaust gas temperature is high, optimum regeneration control based on the trapped amount cannot be performed. However, in a general internal combustion engine, the state where the exhaust gas temperature is high does not last for a long time. Therefore, by not performing the regeneration in the state where the exhaust gas temperature is high, it is possible to prevent an error in detecting the amount of trapped particulates.

FIG. 4 shows another embodiment of the present invention. 4, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Two devices for measuring the exhaust gas temperature are provided: an upstream exhaust gas temperature measuring device 37 and a downstream exhaust gas temperature measuring device 30. The temperature of the exhaust gas changes in a short time according to the engine load and the number of revolutions, but the temperature of the filter 19 has a large time constant because of its large thermal resistance. Therefore, the exhaust gas temperature and the filter temperature may not always match. In order to avoid this, the exhaust gas temperature is measured at two locations upstream and downstream of the filter, and when the temperature difference is small, the magnetron 20 is operated for a short time to detect the amount of particulates. It can be said that the temperature of the filter 19 and the temperature of the exhaust gas are almost equal to each other where the upstream temperature and the downstream temperature substantially match.

By providing such two exhaust gas temperature measuring devices, the accuracy of measuring the temperature of the filter is improved and the amount of collected particulates can be detected more accurately. As a result, it is possible to realize a filter regeneration device for an internal combustion engine capable of performing optimal filter regeneration control.

[0042]

As described above, the filter regenerating apparatus for an internal combustion engine of the present invention has the following effects.

The physical quantity of particulates is detected by the quantity of electric power received by the antenna for detecting high frequencies, and the detected quantity is corrected by the exhaust gas temperature information. Therefore, high-frequency power for regeneration control is used in accordance with the quantity of particulates. Since the auxiliary combustion gas is supplied, it is possible to perform heating regeneration while suppressing the combustion temperature of the filter, which has the effect of improving safety and durability.

Further, the exhaust gas temperature measuring device is attached near the exhaust gas discharge portion of the filter, so that the accuracy of measuring the exhaust gas temperature can be improved.

Further, by stopping the regeneration operation when the exhaust gas temperature is high, the detection accuracy of the amount of particulates can be improved and erroneous regeneration control can be prevented.

Further, since the exhaust gas temperature measuring means is provided at both the intake portion and the exhaust portion of the particulate filter, the filter temperature can be measured more accurately, so that optimum filter regeneration control can be performed and reliability can be improved. A high filter regeneration device for an internal combustion engine becomes possible.

[Brief description of drawings]

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

FIG. 2 is a partial detailed view of a filter regenerating device for an internal combustion engine according to an embodiment of the present invention.

FIG. 3 is a characteristic diagram of antenna detection power and particulate collection amount in the embodiment of the present invention.

FIG. 4 is a configuration diagram of an internal combustion engine filter regenerating apparatus according to another embodiment of the present invention.

FIG. 5 is a block diagram of a conventional high-frequency heating device.

[Explanation of symbols]

 17 Exhaust Pipe 18 Heating Chamber 19 Filter 20 High Frequency Generator (Magnetron) 22 Blower Means 28 Filter Holding Material 29 Antenna 30 Exhaust Gas Temperature Measuring Device (Downstream Side) 31 Control Part 37 Exhaust Gas Temperature Measuring Device (Upstream Side)

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

Claims (5)

[Claims] 1. An exhaust pipe for discharging exhaust gas of an internal combustion engine,
A filter that is housed in the exhaust pipe and collects particulates contained in the exhaust gas, and a heating chamber that houses the filter and heats and burns the particulates,
A high-frequency generator that generates a high-frequency for heating the particulates, an antenna provided in the heating chamber for detecting the high-frequency in the heating chamber, and a blower gas that supplies an auxiliary combustion gas for burning the particulates to the filter. Means, a filter temperature measuring means for the filter, and a control unit for controlling the operation of the high frequency generator and the blower means based on a detection signal from the antenna and information from the filter temperature measuring means Filter regenerator. 2. An exhaust pipe for discharging exhaust gas of an internal combustion engine,
A filter that is housed in the exhaust pipe and collects particulates contained in the exhaust gas, and a heating chamber that houses the filter and heats and burns the particulates,
A high-frequency generator that generates a high-frequency for heating the particulates, an antenna provided in the heating chamber for detecting the high-frequency in the heating chamber, and a blower gas that supplies an auxiliary combustion gas for burning the particulates to the filter. Means, exhaust gas temperature measuring means for measuring the temperature of the exhaust gas, a control unit for controlling the operation of the high-frequency generator and the blowing means based on the detection signal from the antenna and the information from the exhaust gas temperature measuring means A filter regeneration device for an internal combustion engine. 3. The filter regenerating apparatus for an internal combustion engine according to claim 2, wherein the exhaust gas temperature measuring means is provided outside the heating chamber, and is provided in the vicinity of the exhaust gas discharge portion of the heating chamber that houses the filter. 4. Exhaust gas temperature measuring means is provided both on the exhaust gas upstream side and downstream side of the heating chamber, and heating is performed when the temperature of the upstream side exhaust gas temperature measuring means and the temperature of the downstream side exhaust gas temperature measuring means become substantially the same. 3. The filter regeneration device for an internal combustion engine according to claim 2, further comprising a control unit that controls a high frequency generator and a blower based on a detection signal of an antenna that detects a high frequency of the chamber and information of the exhaust gas temperature measuring unit. 5. The antenna comprises a center conductor of a coaxial line,
The filter regeneration device for an internal combustion engine according to claim 1 or 2, wherein the filter regeneration device is provided on a wall surface that houses and covers the filter.