JPH04353208A - Exhaust gas purification device for internal combustion engines - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention uses microwave energy to heat and raise the temperature of a purification means that decomposes harmful substances such as hydrocarbons and carbon monoxide in exhaust gas emitted from internal combustion engines such as automobiles. It is related to the device.

0002

2. Description of the Related Art Pollutants emitted from automobiles have been viewed as a problem as one of the sources of air pollution, and regulations on automobile exhaust gas have been gradually implemented since the beginning of 1965. In recent years, there has been a movement in countries around the world to tighten emission regulations for air pollutants.In particular, regulations regarding automobile exhaust gas have been shifted from conventional concentration regulations to total volume regulations, and the regulatory values themselves have also been significantly reduced. ing.

[0003] Among automobiles, gasoline-powered cars are subject to stricter emission regulations for hydrocarbons, carbon monoxide, and nitrogen oxides contained in exhaust gas. Methods for purifying these pollutants include engine combustion methods such as complex swirl combustion and lean combustion, and after-treatment methods using catalysts, but the after-treatment method using catalysts, which is technically and economically superior, has now been put into practical use. has been done. The catalyst used in this after-treatment method is an oxidation catalyst that oxidizes hydrocarbons and carbon monoxide and converts them into harmless carbon dioxide and water vapor (EGR etc. may be used in combination to reduce nitrogen oxides); There is a three-way catalyst that simultaneously oxidizes hydrocarbons and carbon monoxide and reduces nitrogen oxides by controlling the air-fuel ratio to near the stoichiometric air-fuel ratio, converting them into harmless carbon dioxide, water vapor, and nitrogen. Catalysts are mainly installed in passenger cars.

FIG. 6 shows a conventional exhaust gas purification device installed in a passenger car. In the figure, 1 is an engine, 2 is an exhaust manifold, 3 is an exhaust pipe, 4 is an oxygen sensor, 5 is a three-way catalyst, 6 is a container for storing the catalyst, 7 is an exhaust temperature sensor, and 8 is a muffler. A conventional exhaust gas purification device is composed of a three-way catalyst body 5 and a container 6, and the three-way catalyst body 5 is disposed in the middle of an exhaust pipe 3 connected to an exhaust manifold 2. As disclosed in Japanese Patent Publication No. 52-3358, the three-way catalyst 5 has fine particles such as alumina having a large surface area on a support made of a ceramic honeycomb structure of cordierite whose main components are silica, alumina, and magnesia. A coating layer is provided, and fine particles of noble metals such as alloys, palladium, and rhodium are supported on this coating layer.

In the above configuration, when the engine 1 is started, exhaust gas from combustion passes through the exhaust manifold 2 and is guided to an exhaust gas purification device provided midway through the exhaust pipe 3. This exhaust gas passes through each cell forming the honeycomb structure of the three-way catalyst body 5 and is discharged to the atmosphere from the exhaust pipe 3. At this time, the air-fuel ratio is controlled near the stoichiometric air-fuel ratio by the oxygen sensor 4, and the hydrocarbons, carbon monoxide, and
Nitrogen oxides are converted into harmless carbon dioxide, water vapor, and nitrogen by the oxidation and reduction reactions of the three-way catalyst 5. However, in order for the above reaction to occur, it is necessary to raise the temperature of the three-way catalyst 5 to a temperature at which it functions as a catalyst. This three-way catalyst body 5 is heated by the heat of the exhaust gas, but at a cold start, it takes about 1 minute to reach the temperature at which it functions as a catalyst.
Until then, harmful exhaust gases will be released into the atmosphere.

In order to reduce the emission of harmful exhaust gases, a metal honeycomb (supporting a catalyst) having a smaller volume than the three-way catalyst body 5 is arranged in front of the three-way catalyst body 5, and this is connected to an electric heater. Methods have been studied to shorten the time it takes to reach a temperature that functions as a catalyst by rapidly heating the catalyst using a heating means such as a burner, but this method has not yet reached a practical level.

[0007]

However, in the above-mentioned conventional configuration, since the catalyst body is heated by the exhaust gas as described above, it takes about one minute to reach the temperature at which it functions as a catalyst. Although this situation clears the current exhaust gas regulations, the amount of harmful substances (especially hydrocarbons) emitted in the exhaust gas at the time of cold start becomes a problem due to the exhaust gas regulations that will be further tightened in the future. However, it is difficult to meet this requirement with current exhaust gas purification devices.

[0008] Furthermore, the conventional method of heating the metal honeycomb placed in front of the three-way catalyst body with a burner has a narrow heating range, and it is difficult to bring the entire metal honeycomb to a temperature at which it functions as a catalyst in a short period of time. There was also the problem that hydrocarbons were generated from the heating means of the burner.

[0009] Furthermore, the method of using an electric heater instead of a burner requires a large amount of electric power (large current), and there is a problem in that it is practically difficult to supply sufficient driving power from the automobile power source.

[0010] The present invention solves the above-mentioned problems, and uses microwaves to rapidly heat a purifying means for decomposing harmful substances contained in exhaust gas, thereby reducing harmful substances in exhaust gas at the time of a cold start. The object of the present invention is to provide a device that can sufficiently supply driving power for a microwave generation source from an automobile power source.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a heating chamber provided in the middle of an exhaust pipe for discharging exhaust gas from an internal combustion engine, and generating microwave energy to supply power to the heating chamber. and a purification means housed in the heating chamber that decomposes harmful substances contained in the exhaust gas using heat generated by the high frequency.

[0012] In addition to the above configuration, the present invention is also provided with a blower means for supplying oxygen-containing gas to the heating chamber.

[0013] In addition to the above configuration, the present invention is also provided with a control means for controlling the operation of the high frequency oscillator and the air blowing means.

[0014] The purifying means uses a radio wave absorbing material that efficiently absorbs microwaves and a catalyst that promotes the decomposition of harmful substances.

[0015]

[Operation] According to the above-described structure, microwave energy is supplied to the heating chamber at the same time as the engine of a gasoline-powered vehicle starts, and the purifying means for decomposing harmful substances in the exhaust gas stored in the heating chamber is heated. Ru. At this time, since the purification means uses a radio wave absorbing material that efficiently absorbs microwaves, the temperature can be raised to a temperature that decomposes harmful substances such as hydrocarbons and carbon monoxide contained in the exhaust gas in an extremely short time. , a decomposition reaction due to oxidation occurs and the gas is converted into harmless water vapor and carbon dioxide gas, which is released into the atmosphere through the exhaust pipe. Furthermore, by using a radio wave absorbing material that efficiently absorbs microwaves in the purification means, the power consumption for generating microwave energy can be reduced, so that the drive power for the high frequency generation source can be sufficiently supplied from the automobile power source. can do.

Furthermore, by providing a blower means for supplying gas containing oxygen to the heating chamber, oxygen necessary for oxidative decomposition of hydrocarbons and carbon monoxide, which are harmful substances in the exhaust gas, can be sufficiently supplied. can do. Therefore, by supplying oxygen-containing gas from the blowing means to the purification means heated by microwave energy, the progress of the oxidation reaction of hydrocarbons and carbon monoxide can be accelerated, resulting in higher purification of harmful substances. performance can be obtained.

[0017] In addition to the above-mentioned configuration, by providing a configuration including a high-frequency oscillator, a detection means for controlling the operation of the air blowing means, and a control means, the purification means can self-heat by microwave heating and oxidative decomposition of harmful substances. Even if an abnormally high temperature condition occurs in the apparatus, the detection means detects this condition, and the control means which receives this detection signal controls the microwave energy of the high frequency oscillator or the blowing means. This makes it possible to avoid the above-mentioned abnormal high temperature state, and prevent cracks and melting of the carrier constituting the purifying means, as well as scattering of the radio wave absorbing material and catalyst supported on the carrier. Furthermore, the control means can efficiently purify exhaust gas by controlling the supply of microwave energy and the blowing of gas containing oxygen at the same time as the engine is started.

Furthermore, by using a catalyst that decomposes harmful substances at low temperatures in the purification means, the above-mentioned decomposition reaction of harmful substances can be caused from low temperatures, so that the purification performance is further improved and the energy required for generation of microwave energy is improved. power consumption can be further reduced.

Furthermore, by constructing the purifying means by supporting a radio wave absorbing material and a catalyst on a carrier made of a honeycomb structure of ceramic fibers, the heat capacity can be reduced, so that the heating rate and heat transfer of the purifying means can be reduced. It is possible to speed up the purification process, which is advantageous in improving the purification performance of the harmful substances, and since the temperature difference between the purification means can be reduced, it is possible to prevent the occurrence of cracks due to thermal factors.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, 9 is an exhaust pipe for discharging exhaust gas from an internal combustion engine, 10 is a heating chamber provided in the middle of the exhaust pipe 9, and 11 is housed in the heating chamber 10, and is heated while the exhaust gas is passing through. A purifying means for decomposing hydrocarbons and carbon monoxide, which are harmful substances contained in exhaust gas, 12 is a support member for supporting the purifying means 11 in the heating chamber 10; It also serves as a heat insulator between the outer circumference of the heating chamber 10 and the inner wall of the heating chamber 10. 13 is a high frequency oscillator that generates microwave energy to supply power to the heating chamber 10;
4 is a cooling means for cooling the high frequency oscillator 13, and 15 is a waveguide for transmitting the microwave generated from the high frequency oscillator 13 to the heating chamber 10. Microwave shielding means 16 and 17 define the heating chamber 10, and are made of a metal plate having a large number of punched holes or a metal honeycomb structure having a large number of through holes.

Exhaust gas discharged from the engine flows through the exhaust pipe 9 in the direction indicated by the arrow in FIG. 1, and flows into the purifying means 11. Harmful substances such as hydrocarbons and carbon monoxide contained in the inflowing exhaust gas are purified by the purifying means 11, and the purified exhaust gas is discharged into the atmosphere from the exhaust pipe 9.

FIG. 2 shows the appearance of the purifying means 11 used in the exhaust gas purifying apparatus of the present invention. Purification means 1
As the first carrier, as shown in FIG. 2, a honeycomb structure having a large number of communication holes formed by ceramic partition walls is applied. This honeycomb structure carrier is made by corrugating a porous sheet made of ceramic fibers such as alumina, silica, and zirconia, and by extrusion molding of cordierite ceramic powder whose main components are alumina, silica, and magnesia. . A radio wave absorbing material that absorbs microwaves and, if necessary, a catalyst that decomposes harmful substances in exhaust gas at low temperatures are supported on the carrier made of the honeycomb structure described above.

FIG. 3 is a partial sectional view of the purifying means 11 showing a state in which the radio wave absorbing material and the catalyst are supported. Figure (a)
1 is a case where the carrier made of a honeycomb structure is made of ceramic fibers, 18 is a ceramic fiber, 19 is a radio wave absorbing material, and 20 is a catalyst. ceramic fiber 1
Since the sheet composed of 8 is porous, the radio wave absorbing material 19 and the catalyst 20 are supported not only on the surface of the sheet but also inside the sheet. On the other hand, FIG. 2B shows a case where the carrier consisting of a honeycomb structure is made of ceramic powder, and 21 indicates a ceramic partition made of a sintered body of the powder. Since the ceramic partition wall 21 is dense, most of the radio wave absorbing material 19 and the catalyst 20 are supported on the surface of the ceramic partition wall.

Next, a basic process for purifying harmful substances contained in exhaust gas in the exhaust gas purification apparatus of the present invention will be explained.

When the gasoline engine is started, the high frequency oscillator 13 generates microwaves in response to a command from a control section (not shown). This microwave is transmitted through a waveguide 15 and is supplied to a heating chamber 10 housing a purifying means 11. The radio wave absorbing material 19 constituting the purifying means 11 absorbs the supplied microwave energy and converts it into thermal energy, so that the temperature of the purifying means 11 rises in a very short time due to the converted thermal energy. On the other hand, exhaust gas containing harmful substances such as carbon monoxide and hydrocarbons discharged from the engine flows into the purifying means 11 through the exhaust pipe 9. At this time, since the temperature of the purifying means 11 is raised by the microwave, the carbon monoxide and hydrocarbons mentioned above react with the oxygen contained in the exhaust gas and are decomposed into harmless water vapor and carbon dioxide, which pass through the muffler. The purified exhaust gas is discharged into the atmosphere through the exhaust pipe 9.

By supporting the radio wave absorbing material 19 having high microwave absorption ability on the carrier constituting the purifying means 11, when a microwave method is applied as a heating means for the purifying means 11 described above, an electric heater method can be used. The power consumption can be reduced to about half that of the case where the temperature is increased, and the driving power for the microwave generation source can be sufficiently supplied from the automobile power supply.

[0028] Semiconductor materials can be cited as radio wave absorbing materials with high microwave absorption ability, and in particular, metal oxides which are compounds of zinc, copper, manganese, cobalt, iron, tin, titanium and oxygen, and perovskite type composite oxides. Composite oxides containing the above-mentioned metals as main components, such as metals, and those made of at least one of silicon carbide are used. The mechanism by which the above material absorbs microwaves and converts them into heat is not clear, but can be considered as follows. In the above materials, the combination state of metal, oxygen, and carbon is not stoichiometrically balanced, and when the electrons or protons of the compound become deficient or saturated, the period of the electromagnetic field caused by microwaves changes. In response to this, the electron or proton carriers repeatedly move within the compound, and this movement generates heat. In the case of microwaves, the frequency used is 2450 MHz, and the period is 2450×10 6 , making it possible to obtain a very large amount of heat. Therefore, it can be said that a type of semiconductor material generates a large amount of heat due to absorption of microwaves.

The temperature increase characteristic of the above material due to microwave absorption is shown in FIG. 3(a). Zinc oxide is supported as a radio wave absorbing material on a carrier made of a honeycomb structure of about 200 cc ceramic fibers, and the exhaust gas shown in FIG. When the power consumption of microwave power supply was about 1 kW in the configuration of the gas purification device, the temperature after 30 seconds of microwave power supply was about 600°C. Further, when a mixture of copper, manganese, and cobalt oxides was used instead of zinc oxide, the temperature was about 550°C. In addition, when the purification performance was evaluated using a hydrocarbon analyzer using propylene gas at a concentration of 800 ppm as a model exhaust gas under the above configuration and conditions, a purification rate of approximately 50% was obtained within 1 minute after microwave power supply. In addition, when the other radio wave absorbing materials mentioned above were used, substantially the same temperature increase characteristics and purification performance as those described above were obtained.

Furthermore, the purification performance can be improved by supporting a catalyst that decomposes carbon monoxide and hydrocarbons, which are harmful substances in exhaust gas, at low temperatures together with a radio wave absorbing material on the carrier made of the honeycomb structure described above. . Examples of this catalyst include platinum, palladium, rhodium, and perovskite type composite oxides, and at least one of these is supported on a carrier having a honeycomb structure. When palladium was supported as a catalyst and the purification performance was evaluated under the same conditions as above, a purification rate of about 70% was obtained. It should be noted that almost the same purification performance was obtained with the other catalysts mentioned above. Furthermore, when the engine is operated near the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas is extremely low, so the catalyst preferably has a three-way catalyst composition of platinum and rhodium or palladium and rhodium. By using this catalyst composition,
Oxidation-reduction reactions can occur between nitrogen oxides, hydrocarbons, and carbon monoxide in exhaust gas, and the harmful substances can be purified even in an oxygen-deficient exhaust gas atmosphere.

The carrier made of the ceramic honeycomb structure may be either shown in FIGS. 3(a) or 3(b).
The carrier made of ceramic fibers shown in a) has a smaller heat capacity (smaller weight per unit volume), so it can increase the temperature and transfer heat to the entire carrier faster, and has better temperature increase characteristics. and a product with excellent purification performance can be obtained. Furthermore, since heat transfers quickly, the temperature difference between the carriers can be reduced, and therefore cracks caused by thermal distortion can be prevented.

The purpose of the exhaust gas purification device of the present invention is to purify the exhaust gas at the time of cold start of a gasoline-powered vehicle, so under normal driving conditions, it can be used in conjunction with a conventional three-way catalyst to further improve the performance. Exhaust gas purification performance can be achieved. At this time, the three-way catalyst body may be placed either before or after the exhaust gas purification device of the present invention.

FIG. 4 shows the configuration of an exhaust gas purification device for an internal combustion engine in another embodiment of the present invention. In the figure, the same members and the same functional members as in FIG. 1 are indicated by the same numbers. The difference from FIG. 1 is that the exhaust gas purification device is provided with a blower means for supplying gas containing oxygen. Reference numeral 22 denotes a blowing means for supplying a gas containing oxygen to the heating chamber 10 . The blowing means 22 is a blower or a pump, and the gas is guided into the heating chamber 10 through an air guide pipe 23 . Further, a valve 24 is provided in the middle of the air guide pipe 23 to control the blowing of the gas. This valve 24 is closed so that exhaust gas from the engine does not flow into the blowing means 22 when the exhaust gas purification device of the present invention is not used.

Oxygen is required to decompose harmful substances such as hydrocarbons and carbon monoxide in exhaust gas and convert them into water vapor and carbon dioxide. However, when the engine is operated near the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas is extremely low, causing the problem that the above reaction does not occur smoothly. In the present invention, as shown in the above configuration, the above reaction can be smoothly caused by supplying the gas containing oxygen required for oxidative decomposition of the harmful substances to the heating chamber 10 from the blowing means 22. This makes it possible to improve the purification performance of harmful substances such as hydrocarbons and carbon monoxide contained in exhaust gas. Note that if the amount of oxygen supplied from the blowing means 22 is greater than the amount required for the above reaction, the concentration of nitrogen oxides in the exhaust gas tends to increase. Therefore, it is preferable to control the amount of oxygen supplied to the amount necessary to cause the above reaction to occur smoothly.

When the purification performance was evaluated under the same conditions as described above, using the above-mentioned air blowing means, a carrier made of a honeycomb structure of ceramic fibers was loaded with zinc oxide as a radio wave absorbing material and palladium as a catalyst. A purification rate of about 85% was obtained.

FIG. 5 shows the configuration of an exhaust gas purification device for an internal combustion engine in another embodiment of the present invention. In the figure, the same members and the same functional members as in FIGS. 1 and 2 are indicated by the same numbers. The difference from FIGS. 1 and 2 is that the exhaust gas purification apparatus is provided with a detection means and a control means for controlling the operation of the high frequency oscillator 13 and the blower means 22. Reference numeral 25 denotes a detection means provided in the exhaust pipe 9 on the exhaust gas downstream side of the heating chamber 10 housing the purification means 11, and this detection means 25 is a temperature sensor that detects the temperature of the exhaust gas. 26 is a control means for controlling the high frequency oscillator 13 and the air blowing means 22, and 27 is a driving power source. The control means 26 is configured to receive the signal from the detection means 25 and to judge this signal to control the operation of the high frequency oscillator 13 or the blower means 22.

The above-mentioned oxidative decomposition reaction of hydrocarbons and carbon monoxide is a combustion reaction and is accompanied by self-heating. As the concentration of hydrocarbons and carbon monoxide in the exhaust gas discharged from the engine increases, the amount of self-heat generated by the decomposition reaction increases, and when the heat generated by the absorption of microwaves by the purification means 11 is added to this, the temperature becomes higher than necessary. condition may occur. This high-temperature state may cause cracks or melting damage to the carrier made of the ceramic honeycomb structure that constitutes the purifying means 11.
There is a possibility that the radio wave absorbing material and catalyst supported on it will be scattered. In the present invention, as shown in the above configuration, the detection means 25 such as a temperature sensor provided in the exhaust pipe 9 on the exhaust gas downstream side of the heating chamber 10 monitors the exhaust temperature, and the control means 26 receives the temperature information. It looks like this. and control means 2
6 is determined to enter a high temperature state from a change in exhaust gas temperature or temperature gradient, it controls the microwave energy of the high frequency oscillator 13 or the gas supply amount of the blower means 22 to prevent the purification means 11 from entering a high temperature state. can be avoided. As a result, it is possible to prevent cracks and melting of the ceramic honeycomb structure carrier constituting the purification means 11, and to prevent scattering due to evaporation of the supported radio wave absorbing material and catalyst, and prevent the initial exhaust gas from being scattered. Purification performance can be made permanent. Note that the supply amount of the gas containing oxygen can also be controlled by a valve 24 provided in the middle of the air guide pipe 23.

Furthermore, since the control means 26 controls the high frequency oscillator 13 and the blower means 22 to operate at the same time as the engine is started, exhaust gas can be efficiently purified.

Note that the operation of the high-frequency oscillator 13 and the blower means 22 does not need to continue while the engine is running, and the exhaust gas from the engine raises the temperature at which the purifying means 11 can decompose harmful substances in the exhaust gas. Once the temperature can be maintained, operation can be stopped or its power reduced.

Further, in order to further improve the exhaust gas purification performance, other heating means may be arranged to heat the oxygen-containing gas and supply it to the heating chamber 10.

[0041]

As explained above, according to the exhaust gas purifying device for an internal combustion engine of the present invention, the following effects can be obtained. (1) Since the purification means of the present invention uses a radio wave absorbing material that efficiently absorbs microwaves, it can reach a temperature that decomposes harmful substances such as hydrocarbons and carbon monoxide contained in exhaust gas in an extremely short time. It can be heated to a temperature of 100% and converted into harmless water vapor and carbon dioxide through an oxidative decomposition reaction. Therefore, it is possible to purify the harmful substances contained in the exhaust gas when the automobile engine is cold-started, and it is possible to prevent the harmful substances from being discharged into the atmosphere. (2) Furthermore, by using a radio wave absorbing material that efficiently absorbs microwaves in the purification means, the power consumption for generating microwave energy can be reduced, so that the driving power source for the high frequency generation source can be used from the automobile power source. It can be supplied in sufficient quantity and can be operated repeatedly. (3) Furthermore, by using a catalyst that decomposes harmful substances at low temperatures in the purification means, the decomposition reaction of hydrocarbons and carbon monoxide, which are harmful substances, can occur at low temperatures, which further improves the purification performance. The power consumption required to generate microwave energy can be further reduced. (4) Furthermore, by configuring the purifying means by supporting a radio wave absorbing material and a catalyst on a carrier made of a honeycomb structure of ceramic fibers, the heat capacity can be reduced, so that the heating rate of the purifying means and the heat transfer can be reduced. This is advantageous in improving the purification performance of the harmful substances, and since the temperature difference between the purifying means can be reduced, it is possible to prevent cracks from occurring due to thermal factors. (5) By providing a blowing means for supplying a gas containing oxygen, oxygen necessary for oxidative decomposition of hydrocarbons and carbon monoxide, which are harmful substances in the exhaust gas, can be supplied to the purifying means. As a result, the progress of the oxidation reaction of hydrocarbons and carbon monoxide can be accelerated, so that higher performance in purifying harmful substances can be obtained. (6) By providing a control means for controlling the operation of the high-frequency oscillator and the blowing means based on a signal from a detection means for detecting the state of exhaust gas, the purification means can be self-contained by microwave heating and oxidative decomposition of harmful substances. Even if an abnormally high temperature state occurs due to heat generation, the detection means detects this state, and upon receiving this detection signal, the control means controls the microwave energy of the high frequency oscillator or controls the blowing means. This makes it possible to avoid the above-mentioned abnormal high temperature state. As a result, cracks in the carrier made of the ceramic honeycomb structure constituting the purification means,
It is possible to prevent the occurrence of melting loss and scattering of the radio wave absorbing material and catalyst supported on the carrier due to evaporation, and the initial purification performance can be maintained permanently. (7) Furthermore, the control means can efficiently purify the exhaust gas by controlling the high frequency oscillator and the blowing means for gas containing oxygen at the same time as the engine is started.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an exhaust gas purification device for an internal combustion engine in an embodiment of the present invention.

[Fig. 2] External view of purification means in one embodiment of the present invention

[
FIG. 3: Partial cross-sectional view of purifying means in one embodiment of the present invention

FIG. 4 is a configuration diagram of an exhaust gas purification device for an internal combustion engine in another embodiment of the present invention.

FIG. 5 is a configuration diagram of an exhaust gas purification device for an internal combustion engine in another embodiment of the present invention.

[Figure 6] Configuration diagram of a conventional exhaust gas purification device

[Explanation of symbols]

9 Exhaust pipe 10 Heating chamber 11 Purification means 12 Holding member 13 High frequency oscillator 14 Cooling means 15 Waveguide 16, 17 Microwave shielding means 18 Ceramic fiber 19 Radio wave absorbing material 20 Catalyst 21 Ceramic partition wall 22　Air blowing means 23　Wind pipe 24 Valve 25 Detection means 26 Control means 27 Drive power supply

Claims (11)

[Claims] Claims: 1. A heating chamber provided in the middle of an exhaust pipe for discharging exhaust gas from an internal combustion engine; a high-frequency oscillator that generates microwave energy to supply electricity to the heating chamber; An exhaust gas purification device for an internal combustion engine, comprising a purifying means for decomposing harmful substances contained in exhaust gas using generated heat. 2. A heating chamber provided in the middle of an exhaust pipe for discharging exhaust gas of an internal combustion engine; a high-frequency oscillator that generates microwave energy to supply power to the heating chamber; An exhaust gas purification device for an internal combustion engine, comprising a purification means that decomposes harmful substances contained in exhaust gas using generated heat, and a blower means that supplies gas containing oxygen to the heating chamber. 3. A heating chamber provided in the middle of an exhaust pipe for discharging exhaust gas from an internal combustion engine; a high-frequency oscillator that generates microwave energy to supply electricity to the heating chamber; A purifying means that decomposes harmful substances contained in the exhaust gas by the generated heat, a blowing means that supplies gas containing oxygen to the heating chamber, and a signal from the detecting means that detects the state of the exhaust gas in the exhaust pipe. An exhaust gas purification device for an internal combustion engine, comprising a control means for controlling the operation of the high frequency oscillator and the blowing means. 4. The exhaust gas purification device for an internal combustion engine according to claim 1, wherein the purifying means for decomposing harmful substances comprises a ceramic carrier and a radio wave absorbing material supported on the carrier and absorbing high frequency waves. . 5. A purification means for decomposing harmful substances comprises a ceramic carrier, a radio wave absorbing material supported on the carrier that absorbs high frequency waves, and a catalyst supported on the carrier that promotes the decomposition of the harmful substances. Item 4. The exhaust gas purification device for an internal combustion engine according to any one of Items 1 to 3. 6. The exhaust gas purification device for an internal combustion engine according to claim 5, wherein the catalyst that promotes purification of harmful substances comprises at least one of platinum, rhodium, palladium, and perovskite type composite oxide. 7. The exhaust gas purification device for an internal combustion engine according to claim 4, wherein the radio wave absorbing material that absorbs microwaves is made of a semiconductor material. 8. The semiconductor material according to claim 7, comprising at least one of metal oxides of zinc, copper, manganese, cobalt, iron, tin, and titanium, composite metal oxides containing the above metals as main components, and silicon carbide. Exhaust gas purification device for internal combustion engines. 9. The exhaust gas purifying device for an internal combustion engine according to claim 4, wherein the ceramic carrier comprises a honeycomb structure having a large number of communicating holes. 10. The exhaust gas purification device for an internal combustion engine according to claim 4, wherein the ceramic carrier comprises a heat-resistant inorganic fiber of at least one of alumina, silica, and zirconia. 11. The exhaust gas purification device for an internal combustion engine according to claim 3, wherein the detection means comprises means for detecting the temperature of the exhaust gas that has passed through the purification means.