JP2850645B2 - Exhaust gas purification 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 exhaust gas purifying apparatus for decomposing harmful substances such as hydrocarbons and carbon monoxide in exhaust gas discharged from an internal combustion engine of an automobile or the like by using heating means using high-frequency energy. It is about.

[0002]

2. Description of the Related Art In automobiles that use gasoline as fuel, there is a movement to tighten regulations on the emission of hydrocarbons, carbon monoxide, and nitrogen oxides contained in exhaust gas. One of the methods for purifying these pollutants is a post-treatment method using a catalyst, which is currently in practical use. A typical catalyst used in this post-treatment system is to control the air-fuel ratio to near the stoichiometric air-fuel ratio to simultaneously oxidize hydrocarbons and carbon monoxide and reduce fossil oxides, and to use harmless carbon dioxide and steam. There is a three-way catalyst for converting to nitrogen, and this three-way catalyst is mainly mounted on passenger cars.

FIG. 5 shows a conventional exhaust gas purifying unit mounted on 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 containing the three-way catalyst 5, 7
Is an exhaust gas temperature sensor, 8 is a muffler, and a conventional exhaust gas purifying device is composed of a three-way catalyst 5 and a container 6. The three-way catalyst 5 is disposed in the exhaust pipe 3 connected to the exhaust manifold 2. ing. The three-way catalyst 5 is disclosed in JP-B-52-335.
No. 8, silica, alumina,
A carrier consisting of cordierite ceramic honeycomb structure mainly composed of magnesia is provided with a coating layer made of fine particles such as alumina with a large surface area, and this coating layer carries noble metal fine particles such as platinum, palladium and rhodium. Have been.

When the engine 1 is started, the exhaust gas generated by the combustion passes through the exhaust manifold 2 and is guided to an exhaust gas purifier provided in the exhaust pipe 3. The exhaust gas passes through each cell constituting the honeycomb structure of the three-way catalyst 5 and is discharged from the exhaust pipe 3 to the atmosphere. 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 contained in the exhaust gas are harmless by the oxidation and reduction reactions of the three-way catalyst 5. Converted to carbon dioxide, water vapor and nitrogen. 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. The three-way catalyst 5 is heated by the heat of the exhaust gas, but when the engine at room temperature starts, it takes about one minute to reach a temperature at which the catalyst functions as a catalyst. Will be discharged.

In order to reduce the emission of the harmful exhaust gas, a honeycomb structure made of a metal having a smaller volume than the three-way catalyst 5 is provided on the front surface of the three-way catalyst 5 (supporting a catalyst).
A method for shortening the time required to reach a temperature at which the catalyst functions as a catalyst has been studied, but the method has not yet reached a practical level.

[0006]

In the above-described conventional structure, it takes about one minute to reach a temperature at which the three-way catalyst body functions as a catalyst because it is heated by the exhaust gas. Although this situation has cleared the current exhaust gas regulations, the emission of harmful substances (especially hydrocarbons) in the exhaust gas at the time of the above cold start will be a problem for the exhaust gas regulations that will be further strengthened in the future. However, there is a problem that it is difficult to clear this with the current exhaust gas purification unit.

A conventional method of heating a honeycomb structure made of metal disposed on the front surface of a three-way catalyst body with a burner is as follows.
There have been problems such as generation of hydrocarbons at the time of ignition of the burner and mis-ignition, and poor reliability of the combustion components including the burner.

Further, the method using an electric heater instead of a burner requires large power (large current), making the wires thick and difficult to wire. There is a problem that it is practically difficult to supply them to the public.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and rapidly heats a purifying means for decomposing harmful substances contained in exhaust gas by high-frequency energy to reduce harmful substances in exhaust gas when starting an automobile engine. It is another object of the present invention to provide an exhaust gas purifying apparatus capable of sufficiently supplying a driving power source for a high frequency power source from a vehicle power source.

[0010]

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 generates and supplies high-frequency energy to the heating chamber. High-frequency generating means, and a ceramic housed in the heating chamber, which absorbs high-frequency energy and generates heat.
Carrier and the carrier carried by the ceramic
High frequency absorbing material for absorbing high frequency, and the high frequency absorbing material
Iron-chromium, iron-nicke dispersed on the surface and voids of the material
Alloy of iron-nickel-chromium and nickel-chromium
Metal fine particles composed of at least one metal as a main component
And the high-frequency absorbing material on a carrier made of the ceramic.
And a high frequency heating element comprising an inorganic binder for bonding the metal fine particles, and a high frequency heating element housed in the heating chamber and disposed behind the high frequency heating element with respect to the flow of exhaust gas discharged from the internal combustion engine. And a purifying means for decomposing harmful substances contained in the exhaust gas heated by the heat of the exhaust gas and the heat generated by the high-frequency heating element.

Further, the present invention discharges exhaust gas of an internal combustion engine.
A heating chamber provided in the middle of the exhaust pipe,
High frequency generating means for generating and supplying frequency energy;
Housed in a heating chamber, absorbs high-frequency energy and generates heat
A high-frequency heating element, housed in the heating chamber,
After the high frequency heating element against the flow of exhaust gas
The heat of the exhaust gas and the high-frequency heating element.
Harmful substances contained in exhaust gas heated by the generated heat
The heating chamber is provided with a purifying means for decomposing the substance and a supply means for supplying a gas containing oxygen to the heating chamber.

Further, the present invention provides a high- frequency absorber for a high- frequency heating element.
Fee as, zinc, copper, manganese, cobalt, iron, tin,
Oxide containing titanium as a main component and composite acid containing the metal
And at least one kind of compound.

Further, the present invention is configured such that a purifying means for decomposing harmful substances uses a carrier having a honeycomb structure made of metal or ceramic, and a catalyst for promoting decomposition of harmful substances carried on the carrier. Also, the present invention
Ceramic carrier as ceramic carrier
It has a configuration using a molded body having a honeycomb structure.

[0014]

According to the present invention, the high-frequency energy is supplied to the heating chamber containing the high-frequency heating element at the same time as or immediately before the start of the gasoline engine, and the high-frequency heating element carried by the high-frequency heating element is operated. The high-frequency heating element is heated to a high temperature in a short time by the absorbing material efficiently absorbing the high-frequency energy and converting the heat. The heat accumulated in the high-frequency heating element is transmitted to the purifying means disposed behind the high-frequency heating element together with the heat of the exhaust gas discharged from the engine, and is heated.
The purifying means raises the harmful substances contained in the exhaust gas to a decomposable temperature in several tens of seconds by the heat generated from the high-frequency heating element and the heat of the exhaust gas. It is possible to efficiently purify harmful substances in the exhaust gas.

In the high-frequency heating element, only the high-frequency absorbing material carried on the ceramic carrier absorbs high-frequency energy and generates heat, so that power consumption for generating high-frequency energy can be reduced. Also said high frequency heating
High frequency heat generation by supporting metal fine particles on the body
Since the body can be heated uniformly, the high-frequency heating element
The entire purification means located behind the
To a temperature at which it functions
Can improve the purification performance of harmful substances contained in
You. Further, a cell constituting the high-frequency heating element and the purifying means is provided.
Honey made of ceramic fiber as carrier made of lamic
By using a molded body having a cam structure, the heat capacity can be reduced.
The high-frequency heating element and the purifier can be made smaller
The heating speed of the stage itself and heat transfer are increased, and the exhaust gas
Purification performance can be further improved and the purification
Temperature difference of the gasification means
This can prevent the occurrence of cracks.

On the other hand, about one minute after the start of the engine, the purifying means can be maintained at an abnormal temperature at which the harmful substances can be decomposed by only the exhaust gas. Performance can be maintained.

Further, by providing a supply means for supplying a gas containing oxygen to the heating chamber, the purifying means heated by the high-frequency heating element allows the purifying means heated by the high-frequency heating element to emit hydrocarbons or harmful substances in exhaust gas. Since oxygen necessary for decomposing carbon oxide can be supplied, the progress of the decomposition reaction of the harmful substance can be promoted, and higher purification performance can be obtained.

[0018]

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

In FIG. 1, reference numeral 9 denotes an exhaust pipe for discharging exhaust gas from an internal combustion engine, 10 denotes a heating chamber provided in the middle of the exhaust pipe, 11 denotes a heating chamber which is housed in the heating chamber 10 and absorbs high-frequency energy to generate heat. The high-frequency heating element 12 is housed in the heating chamber 10 and the purifying means for decomposing harmful substances contained in the exhaust gas disposed behind the high-frequency heating element 11 with respect to the flow of the exhaust gas. 11, a heat insulating material for supporting and insulating the purifying means 12; Reference numeral 14 denotes a high-frequency oscillator that generates high-frequency energy to supply power to the heating chamber 10, and 15 denotes a waveguide that transmits the high-frequency generated by the high-frequency oscillator 14 to the heating chamber 10. The exhaust gas inflow side in the heating chamber 10 of the waveguide 15 has a configuration in which high frequency is cut off and a number of punching holes are provided so that the exhaust gas can be introduced into the high frequency heating element 11. Has a configuration in which exhaust gas is passed and an opening for supplying high frequency to the high frequency heating element 11 is provided. In addition, a number of punching holes capable of blocking high frequency may be provided around the opening to reduce pressure loss of exhaust gas. Reference numeral 16 denotes high-frequency cutoff means for preventing high-frequency leakage to the purifying means 12, and is formed of the above-described metal plate having a large number of punched holes or a metal honeycomb structure having a large number of through-holes.

The exhaust gas discharged from the engine flows through the exhaust pipe 9 in the direction indicated by the arrow in FIG.
Flow into 1. The harmful substances such as hydrocarbons and carbon monoxide contained in the inflowing exhaust gas are decomposed by the purifying means 12 heated by the high-frequency heating element 11, and the purified exhaust gas is discharged to the atmosphere through the exhaust pipe 9.

FIG. 2 shows the appearance of the high-frequency heating element 11 used in the exhaust gas purifying apparatus of the present invention. As a carrier of the high-frequency heating element, a honeycomb structure having a large number of communication holes formed by ceramic partitions as shown in FIG. 2 is applied. Carriers made of this honeycomb structure are alumina, silica, corrugated porous sheets made of ceramic fibers such as zirconia and alumina, silica,
It is produced by extrusion molding of cordierite ceramic powder containing magnesia as a main component. The carrier made of the above-mentioned honeycomb structure carries a high-frequency absorbing material that efficiently absorbs high-frequency waves and generates heat, or the high-frequency absorbing material and metal fine particles.

FIG. 3 is a partial sectional view of the high-frequency heating element 11 showing a state in which the high-frequency absorbing material and the fine metal particles are supported on a carrier. FIG. 1A shows a case where a carrier having a honeycomb structure is made of ceramic powder, and reference numeral 17 denotes a ceramic partition of the carrier. Since the ceramic partition 17 is dense, most of the high frequency absorbing material 18 is held on the surface of the ceramic partition 17,
The above-mentioned respective materials are bonded by the inorganic binder 19. On the other hand, FIG. 2B shows the case where the carrier having the honeycomb structure is made of ceramic fibers, and reference numeral 20 denotes ceramic fibers. Since the carrier composed of the ceramic fibers 20 is porous, it is in a state of being supported not only on the surface of the carrier but also inside the carrier, and the above-described materials are bonded by the inorganic binder 19. . FIG. 3C shows the carrier shown in FIG. 3A in which metal fine particles 21 are carried in addition to the high frequency absorbing material 18, and the metal fine particles 21 are uniformly dispersed together with the high frequency absorbing material 18. is there.

The purifying means 12 is obtained by providing a ceramic carrier having a honeycomb structure with a coating layer made of fine particles of alumina or the like having a large surface area, and carrying the noble metal fine particles of platinum, palladium, rhodium or the like on this coating layer (shown in FIG. Zu). Further, instead of the ceramic carrier, a metal carrier having a honeycomb structure having an oxide film formed thereon and the catalyst supported on the oxide film can also be applied.

Next, a purification process by decomposing harmful substances contained in exhaust gas in the exhaust gas purification apparatus of the present invention will be described.

When the engine of the gasoline-powered vehicle starts, exhaust gas containing harmful substances such as carbon monoxide and hydrocarbons discharged from the engine flows into the high-frequency heating element 11 through the exhaust pipe 9. On the other hand, at the same time as or immediately before the start of the engine, the high frequency oscillator 14 controls the control unit (not shown).
A high frequency is generated in accordance with a command from. The high-frequency energy is transmitted through the waveguide 15 and supplied to the heating chamber 10 housing the high-frequency heating element 11. The high-frequency absorbing material 18 constituting the high-frequency heating element 11 absorbs the supplied high-frequency energy and is converted into heat energy, so that the high-frequency heating element 11 is heated to a high temperature. High frequency heating element 11
The heat accumulated in the cleaning device 12 is generated by exhaust gas discharged from the engine,
Is transmitted to The purifying means 12 includes the high-frequency heating element 11 described above.
The harmful substance is heated to a temperature at which the harmful substance can be decomposed in several tens of seconds by heat generated from the exhaust gas and the heat of the exhaust gas, and the harmful substance is decomposed into harmless water vapor and carbon dioxide gas by reacting with oxygen contained in the exhaust gas. Is done. The purified exhaust gas passes through the muffler and is discharged from the exhaust pipe 9 to the atmosphere.

When a carrier made of ceramic powder having a honeycomb structure is used as the high-frequency heating element 11 of the present invention (FIG. 3A), the high-frequency absorbing material 18 is held on the surface of the ceramic carrier. Therefore, heat generated by the high-frequency energy is generated only in the surface layer of the high-frequency heating element 11, so that a high temperature can be obtained, and the heat generated by the exhaust gas can be efficiently transmitted to the purification unit 12. As a result, the purifying means 12 can be raised to a temperature at which the harmful substances can be decomposed in a very short time, and the purification performance of the harmful substances contained in the exhaust gas at the time of starting the automobile engine is improved.

When the ceramic fiber 20 is used as the ceramic carrier (FIG. 3B), the high-frequency absorbing material 18
Can be carried not only on the surface of the high frequency heating element 11 but also on the inside thereof, and can have a porous structure. Therefore, the heat generation surface area of the high-frequency heating element 11 can be increased, and the heat capacity of the high-frequency heating element 11 itself can be reduced, so that the high-frequency heating element 11 can be heated to a high temperature in a shorter time. Can be raised to a temperature at which the harmful substances can be decomposed in a shorter time, and the purification performance of the harmful substances can be further improved.

The high-frequency absorbing material 18 includes metal fine particles 21.
(FIG. 3C), the entire high-frequency heating element 11 can be uniformly heated, and as a result, the
The entire purifying means 12 is used uniformly and as a catalyst.
Can be raised to a temperature at which it can function and is contained in exhaust gas.
Purification performance of harmful substances can be improved.

As described above, the high-frequency heating element 11 is supported by the high-frequency absorbing material 18 having high high-frequency absorbing material characteristics and the fine metal particles 21 supported on the ceramic carrier. In the case where the method is applied, compared with the case where the same temperature rise is obtained by the electric heater heating method (heating of the metal honeycomb carrier), it is 1/3.
The power consumption can be reduced to １ ／ level, and the driving power supply for the high frequency generation source can be sufficiently supplied from the vehicle power supply.

High frequency absorbing material 1 having high high frequency absorbing characteristics
Zinc especially as 8, copper, manganese, cobalt, iron, tin, oxide composed mainly of titanium emission are applied those comprising at least one of the complex oxide containing the metal contact and. The mechanism by which the material absorbs high frequency and converts it into heat is not clear, but it is considered that the material absorbs high frequency and generates heat due to the large dielectric constant and dielectric loss of the semiconductor material.

The metal fine particles 21 used together with the high frequency absorbing material 18 include a metal material having high heat resistance.
Iron -chromium, iron-nickel, iron-nickel-chromium,
At least one type of metal fine particles mainly composed of a nickel-chromium alloy is applied. It is not clear why the use of these metal fine particles together with the high-frequency absorbing material 18 enables the entire high-frequency heating element 11 to be uniformly heated, but the high-frequency characteristics of the high-frequency heating element 11 are improved due to the specific resistance characteristics of the metal particles. It is thought that it is done. Further, the metal fine particles preferably have a small particle size.

The carrier of the high-frequency heating element 11 has heat resistance,
A ceramic material having high mechanical strength can be mentioned, and a honeycomb structure such as cordierite or alumina is applied as a carrier made of ceramic powder, and a honeycomb structure such as alumina, silica, or zirconia is used as a carrier made of ceramic fiber. The body is applied.

The inorganic binder 19 is not particularly limited, but is preferably a colloidal particle of alumina, silica, zirconia or the like having excellent heat resistance and adhesiveness.

Purification means 1 for decomposing harmful substances at a low temperature
Platinum, palladium, rhodium noble metals, copper,
Examples thereof include oxides of manganese and cobalt, and perovskite-type composite oxides, and at least one of them is supported on a ceramic carrier having a honeycomb structure or a metal carrier.

Next, a specific experimental example of the exhaust gas purifying apparatus of the present invention shown in FIG. 1 will be described.

[0036] Figure 3 the honeycomb structure of the ceramic shown in (a) (cordierite, volume 100cc, 200cell / i
nch2), a high-frequency heating element 11 composed of zinc oxide as the high-frequency absorbing material 18 and alumina sol as the inorganic binder 19, and a ceramic honeycomb structure (cordierite, 700 cc, 400 cells / inch2) coated with alumina Using an exhaust gas purifying device (high-frequency power consumption 1.5 kW) shown in FIG. 1 provided with a purifying means 12 constituted by carrying a platinum or rhodium noble metal catalyst on the alumina coating layer. /
min, the engine (displacement: 2000 cc) was operated so that the exhaust gas temperature became 250 to 300 ° C., and the purification performance of hydrocarbons by a hydrocarbon analyzer was evaluated. was gotten. In addition, instead of zinc oxide, which is the high-frequency absorbing material 18, oxides of copper , manganese, cobalt, titanium, tin, and iron, mixtures thereof, composite oxides containing one or more of these metals, titanium-silicon In the case of using a carbon-oxygen compound, almost the same purification performance was obtained. In the case where a perovskite-type composite oxide such as palladium metal, lanthanum, or cobalt, or an oxide of copper, manganese, or cobalt is used instead of platinum or rhodium used as a catalyst in the purification means 12, a purification rate of 50 to 70% is used. was gotten.

A honeycomb structure (alumina-silica fiber, volume: 100 cc, 200 cells / inch ² ) composed of ceramic fibers 20 shown in FIG. 3B as a carrier, silicon carbide whiskers as a high frequency absorbing material 18, inorganic binder 1
High frequency heating element 11 composed of alumina sol 9
And a ceramic honeycomb structure (cordierite,
An exhaust gas purifying apparatus (high-frequency power consumption 1) shown in FIG. 1 comprising a purifying means 12 having a capacity of 700 cc, 400 cell / inch ² ) coated with an alumina coating layer and carrying a noble metal catalyst of palladium on the alumina coating layer. .
5 kw) and the engine (displacement 20
00 cc) was operated and the purification performance of hydrocarbons by a hydrocarbon analyzer was evaluated.
% Purification rate was obtained. When zirconia fibers were used instead of alumina / silica fibers, the same performance as above was obtained.

A ceramic honeycomb structure shown in FIG. 3A (cordierite, volume 100 cc, 200 cells / i
nch2), high-frequency heating element 11 composed of silicon carbide whiskers as high-frequency absorbing material 18, iron-chromium as metal fine particles 21, and alumina sol as inorganic binder 19
And a ceramic honeycomb structure (cordierite,
A volume of 700 cc, 400 cells / inch2) is coated with an alumina coating layer, and the alumina coating layer is formed of platinum,
Purification means 12 configured to support a rhodium noble metal catalyst
The engine (displacement 2000 cc) was operated using the exhaust gas purifying apparatus (high frequency power consumption 1.5 kw) shown in FIG. 1 equipped with the gas and having an exhaust gas amount of about 300 l / min and an exhaust gas temperature of 250 to 300 ° C. When the purification performance of hydrocarbons by a hydrocarbon analyzer was evaluated, a purification rate of about 80% was obtained after 30 seconds of high-frequency power supply. In addition, the iron-
Iron instead of the ROM - nickel, iron - nickel - chromium,
When a nickel-chromium alloy was used, almost the same performance as above was obtained. In addition, as metal fine particles, platinum,
Similar effects can be obtained by using noble metals such as rhodium and palladium.
Fruit can be obtained.

The ceramic carrier having the above-mentioned honeycomb structure may be any of FIGS. 3 (a) and 3 (b).
Since the heat capacity can be reduced (the weight per unit volume is small) by using the ceramic fiber shown in (b), the rate of temperature rise can be increased, and more excellent harmful substance purification performance can be achieved. can get. Further, since the temperature difference of the carrier can be reduced, it is possible to prevent the occurrence of cracks caused by thermal distortion.

On the other hand, about one minute after the start of the engine, the purifying means 12 can be maintained at a temperature higher than the temperature at which the harmful substances can be decomposed by only the exhaust gas. Therefore, high purification performance can be maintained without using heating by high-frequency energy, so that high-frequency oscillation from the high-frequency oscillator 14 is stopped at this time.

FIG. 4 shows the configuration of an exhaust gas purifying apparatus for an internal combustion engine according to another embodiment of the present invention. In the figure, the same members and the same functional members as those in FIG. 1 are denoted by the same reference numerals. The difference from FIG. 1 is that the exhaust gas purifier is provided with a supply unit for supplying a gas containing oxygen. Reference numeral 22 denotes supply means for supplying a gas containing oxygen to the heating chamber 10. The supply means 22 is applied with a blower or various pumps.
It is led to 0. A valve 24 for controlling the supply of the gas is provided in the air guide tube 23. This valve 24 is closed so that the exhaust gas from the engine does not flow into the supply means 22 when the exhaust gas purifying device of the present invention is not used. Reference numeral 25 denotes an antenna that emits high frequency. The high frequency transmitted through the waveguide 15 is radially fed from the antenna 25 to the high frequency heating element 11. in this case,
The waveguide 15 inside the heating chamber 10 does not need an opening for supplying high frequency as shown in FIG. 1, and is provided with a large number of punching holes through which exhaust gas can pass and high frequency can be shielded. Reference numeral 12 denotes a purifying unit formed of a molded metal having a honeycomb structure, and a catalyst formed of a noble metal such as platinum, palladium, or rhodium is supported on an oxide film formed on the metal. When a metal molded body having a honeycomb structure is used as the purifying unit 12, it is not necessary to provide the high-frequency shielding unit 16 shown in FIG.

Oxygen is required to decompose hydrocarbons and carbon monoxide, which are harmful substances in the exhaust gas, and convert them into steam and carbon dioxide. However, when the engine is operated at an air-fuel ratio lower than the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas is in a very low state, and the above-described reaction is not smoothly performed. In the present invention, as shown in the above configuration, the above reaction can be smoothly caused by supplying a gas containing oxygen necessary for decomposing the harmful substance from the supply means 22 to the heating chamber 10. As a result, the performance of purifying harmful substances such as hydrocarbons and carbon monoxide contained in the exhaust gas can be improved.

If the amount of oxygen supplied from the supply means 22 exceeds the amount required for the above reaction, the concentration of nitrogen oxides in the exhaust gas tends to increase.
And the purifying means 12 are cooled. Therefore, it is preferable to control the amount of supplied oxygen to an amount necessary for causing the above reaction to occur smoothly.

[0044]

As described above, according to the exhaust gas purifying apparatus for an internal combustion engine of the present invention, the following effects can be obtained. (1) Since the high-frequency heating element of the present invention uses a high-frequency absorbing material having excellent high-frequency absorption characteristics, it can be heated to a high temperature in a short time, and the heat can be transmitted to the purifying means disposed behind by the exhaust gas flow. The purifying means can be heated in a short time to a temperature at which hydrocarbons and carbon monoxide, which are harmful substances contained in the exhaust gas, are decomposed, and can be converted into harmless water vapor and carbon dioxide gas by a decomposition reaction. Therefore, it is possible to purify the harmful substances contained in the exhaust gas at the time of starting the automobile engine, and to suppress the emission of the harmful substances to the atmosphere. Further, by using metal fine particles for the high-frequency heating element, the entire high-frequency heating element can be uniformly heated, so that a higher purification performance of the harmful substance can be obtained. (2) When the same temperature rise is obtained by a heating method using an electric heater (heating of a metal honeycomb carrier) by supporting a high-frequency absorbing material having high high-frequency absorption characteristics on a ceramic carrier constituting the high-frequency heating element of the present invention. 1/3 compared
The power consumption can be reduced to １ ／ level, and the driving power supply for the high frequency generation source can be sufficiently supplied from the vehicle power supply. (3) By using a ceramic fiber having a honeycomb structure as a carrier of the high-frequency heating element, a porous structure can be obtained, so that the heat capacity is reduced. Therefore, the rate of temperature rise is increased, the purification performance of harmful substances in exhaust gas can be improved, and the temperature difference of the purification means can be reduced, so that cracks due to thermal factors can be prevented. it can. (4) By providing a supply unit for supplying a gas containing oxygen, it is possible to supply the purification unit with oxygen necessary for oxidative decomposition of hydrocarbons and carbon monoxide, which are harmful substances in the exhaust gas. As a result, the progress of the oxidation reaction of hydrocarbons and carbon monoxide can be promoted, so that higher harmful substance purification performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an exhaust gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is an external view of a high-frequency heating element according to one embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a high-frequency heating element according to one embodiment of the present invention.

FIG. 4 is a configuration diagram of an exhaust gas purifying apparatus for an internal combustion engine according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional exhaust gas purification device.

[Explanation of symbols]

 Reference Signs List 9 exhaust pipe 10 heating chamber 11 high-frequency heating element 12 purifying means 13 heat insulating material 14 high-frequency oscillator 15 waveguide 16 microwave shielding means 17 ceramic partition 18 high-frequency absorbing material 19 inorganic binder 20 ceramic fiber 21 metal fine particles 22 supply means 23 wind guide Tube 24 valve 25 antenna

Continuation of the front page (56) References JP-A-4-241717 (JP, A) JP-A-5-171926 (JP, A) JP-A-5-222924 (JP, A) JP-A-5-168861 (JP) , A) (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 3/20 F01N 3/24 F01N 3/32

Claims (7)

(57) [Claims] 1. A heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, a high-frequency generating means for generating and supplying high-frequency energy to the heating chamber, and a high-frequency energy housed in the heating chamber. Ceramic that absorbs heat and generates heat
And a carrier supported by the ceramic carrier.
A high-frequency absorbing material that absorbs high-frequency waves,
Iron-chromium, iron-nickel dispersed on the surface and voids of the material
Kel, iron-nickel-chromium, nickel-chromium alloy
Metal granules consisting of at least one metal whose main component is
And a high-frequency absorber on a carrier made of the ceramic.
Material and an inorganic binder for bonding the metal fine particles.
A high-frequency heating element that is disposed in the heating chamber, is disposed behind the high-frequency heating element with respect to a flow of exhaust gas discharged from the internal combustion engine, and generates heat of the exhaust gas and heat generated by the high-frequency heating element. And a purifying means for decomposing harmful substances contained in the exhaust gas heated by the exhaust gas. 2. A heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, a high-frequency generating means for generating and supplying high-frequency energy to the heating chamber, and a high-frequency energy housed in the heating chamber. A high-frequency heating element that absorbs heat and generates heat, and is disposed in the heating chamber and disposed behind the high-frequency heating element with respect to the flow of exhaust gas exhausted from the internal combustion engine. An exhaust gas purifying apparatus for an internal combustion engine, comprising: purifying means for decomposing harmful substances contained in exhaust gas heated by generated heat; and supply means for supplying a gas containing oxygen to the heating chamber. 3. The high-frequency heating element includes a carrier made of ceramic, a high-frequency absorbing material that absorbs high frequency carried on the carrier made of ceramic, metal fine particles dispersed on the surface and voids of the high-frequency absorbing material, 3. The exhaust gas purifying apparatus for an internal combustion engine according to claim 2, comprising an inorganic binder for bonding the high-frequency absorbing material and the metal fine particles to a ceramic carrier. 4. A high frequency absorbing material for absorbing high frequency is zinc,
Copper, manganese, cobalt, iron, tin, at least one consists of claims 1 or 3 for an internal combustion engine exhaust gas purifying apparatus according to a composite oxide containing Mono及 beauty the metal mainly composed of titanium down. 5. The metal fine particles are iron -chromium, iron-nickel,
4. The exhaust gas purifying apparatus for an internal combustion engine according to claim 3, comprising at least one metal mainly composed of an iron-nickel-chromium or nickel-chromium alloy. 6. The exhaust gas for an internal combustion engine according to claim 1, wherein the purifying means for decomposing the harmful substance comprises a metal carrier or a ceramic carrier having a honeycomb structure, and a catalyst carried on the carrier. Purification device. Claim is a molded body according to claim 7 wherein the carrier made of ceramic having a honeycomb structure by ceramic fibers 1 or
Other exhaust gas purifying device for an internal combustion engine 3 or 6.