JP2827554B2 - Filter regeneration device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for regenerating a filter for an internal combustion engine for collecting particulates (particulate matter) contained in exhaust gas discharged from a diesel engine by using microwave energy. It is.

[0002]

2. Description of the Related Art The high economic growth of so-called developed countries such as Europe, the United States and Japan has greatly contributed to civilization on the earth.
However, the waste of fossil fuel energy, mainly in the economic growth of developed countries, has polluted the Earth's atmosphere.

[0003] With respect to global environmental conservation, measures against global warming, that is, measures for reducing CO2, have been highlighted recently, but measures against acid rain that causes deforestation cannot be ignored.

[0004] Acid rain is a natural phenomenon caused by air pollutants such as sulfur oxides and nitrogen oxides as a polluting source.
There is a trend to strengthen stationary sources such as generation and mobile sources such as automobiles. In particular, regulations on exhaust gas from automobiles have been shifted from conventional concentration regulations to total quantity regulations, and the regulation values themselves have been greatly reduced.

[0005] Among automobiles, diesel cars are subject to stricter regulations on particulate emissions as well as nitrogen oxides. It is said that it is impossible to achieve the exhaust gas regulation value only by the conventional measures for reducing pollutants in exhaust gas by improving combustion such as delaying fuel injection timing. At present, it is indispensable to provide an exhaust gas aftertreatment device. This post-processing device has a filter for collecting particulates.

However, if particulates continue to be collected, the filter will be clogged and the collection capacity will be significantly reduced, and the flow of exhaust gas will be poor, leading to a decrease in engine output or an engine stop.

[0007] Therefore, technology development for regenerating the filter collection capacity is currently being promoted worldwide.
It is not yet practical.

[0008] It is known that particulates burn at about 600 ° C. As means for generating energy for raising particulates to this high temperature range,
A burner method, an electric heater method, a microwave method, and the like have been considered.

The inventors of the present invention have developed a microwave type filter regenerating apparatus in consideration of good temperature rising efficiency, safety, ease of apparatus configuration, and good regenerative control.

Japanese Patent Application Laid-Open No. Sho 59-122022 discloses a microwave filter regenerating apparatus. FIG. 4 shows an apparatus disclosed in the publication. In the figure, 1 is an engine, 2 is an exhaust manifold, 3 is an exhaust pipe, 4 is an exhaust branch pipe, 5 is a filter, 6 is a heating chamber containing the filter, 7 is microwave generating means, 8 is microwave generating means. Waveguide for guiding the generated microwave to the heating chamber, 9 a microwave reflector, 10 an air pump, 11
Is an air supply path, 12 is a driving power supply of the microwave generating means,
13 is a muffler, 14 is an air switching valve, and 15 is an exhaust gas switching valve.

In the above configuration, the exhaust gas of the engine is guided to the filter 5 by the exhaust gas flow switching valve 15 or is directly discharged to the atmosphere. In the particulate collection cycle, the exhaust gas is guided to the filter 5 and the particulates contained in the exhaust gas are collected by the filter 5, but the collection capacity of the filter 5 is limited as described above. When the trapping capacity reaches the limit, the exhaust gas switching valve 15 is controlled, the exhaust gas to the exhaust pipe 3 is shut off, and all of the exhaust gas is exhausted to the atmosphere via the exhaust branch pipe 4. During this time, the regeneration of the filter 5 is performed. In this filter regeneration cycle, energy for heating the particulates is supplied from the microwave generating means 7 and air required for combustion is supplied from the air pump 10 at the same time. When the regeneration of the filter is completed after a predetermined time, the exhaust gas switching valve 15 is controlled again, and the exhaust gas is guided to the filter 5. This cycle of collection and regeneration is repeated.

[0012]

However, in the above-mentioned conventional structure, the combustion air is passed through the filter during the time when the temperature rises to the temperature at which the particulates start burning, so that the temperature rises to the burning temperature of the particulates. A lot of time is required, and there is a problem that it is practical and difficult to supply a driving power supply for the microwave generation source from a power supply mounted on an automobile.

Further, there is a problem that it is difficult to effectively regenerate the entire area of the filter because the combustion air acts to hinder the temperature rise of the particulates and narrows the area where the particulates can be burned. In particular, it was difficult to burn particulates at the filter end face on the exhaust gas inflow side.

Further, there is a problem that the temperature difference of the whole filter is increased by narrowing the region where particulates can be burned, cracks are generated in the filter itself, and the trapping effect of the filter is reduced.

The present invention has been made to solve the above-mentioned problems, and it is possible to shorten the time required to raise the temperature to the temperature at which the particulates burn, shorten the time required to drive the microwave generation source from the vehicle power supply, and effectively reduce the entire filter area. It is an object of the present invention to provide a device that can prevent regeneration and damage to a filter.

[0016]

In order to achieve the above object, the present invention provides a heating chamber provided in an exhaust pipe for exhausting exhaust gas of an internal combustion engine, and a heating chamber housed in the heating chamber and having an exhaust gas contained in the internal combustion engine. A filter for collecting particulates contained in the filter, and a filter disposed on a front surface of the filter on an exhaust gas inflow side.
Ceramic having honeycomb structure without filter function
And click structure, a microwave generator for generating microwaves to power the heating chamber, provided with a air blowing means for supplying air to the heating chamber, a radio wave absorbing material that absorbs the microwave to the filter Is carried.

Further, according to the present invention, in the above configuration, the putty
In front of the exhaust gas inlet side of the filter that collects the particulates
Has a honeycomb structure with no filter function arranged on the surface
Radio wave absorption that absorbs the microwave in ceramic structure
The material is supported .

Further, according to the present invention, in the above configuration, the putty
And a filter for collecting particulates
On the exhaust gas inflow side of the filter that collects gas
With honeycomb structure without filter function
Carrying a radio wave absorbing material that absorbs the microwave on the structure
The configuration is as follows.

[0019] The present invention also relates to the radio wave absorbing material.
Lead, copper, manganese, cobalt, iron, tin and titanium metals
Oxide, composite metal acid having perovskite crystal structure
And at least one of silicon carbide and silicon carbide .

[0020]

According to the present invention, there is provided a particulate matter having the above structure.
When microwaves are applied to the filter where
Filters carry microwave absorbing material
Absorbs well and is converted to heat.
Fast rise and burning of particulates
The microwave irradiation time required to raise the temperature to the temperature can be reduced. Filter is particulate
Is cooled by the air blow necessary for combustion of
The above-mentioned electromagnetic wave absorbing material on the end face of the
Effectively prevents the temperature at the filter end from dropping.
Stopped and particulate collected on the end face of the filter
Can be heated to a flammable temperature and burned.
And the unburned particulates begin to burn
Wave absorption as well as the transmission of the combustion heat of the path Tikyureto was
The filter is heated by microwave absorption of the material.
Raise the temperature of all particulates in a short time and burn
Temperature difference between the filters
The generation of cracks in the filter due to thermal strain is prevented.

Also, the front surface of the filter on the exhaust gas inflow side is
By arranging a ceramic structure with a honeycomb structure
Suppression of air cooling required for particulate combustion
And heated by microwave
Is insulated so that particulates can be reduced to a flammable temperature
The temperature can be raised over time and exists on the end face of the filter
The burning particulates more efficiently
it can.

Also, a voltage is applied to the front of the filter on the exhaust gas inflow side.
Ceramics with honeycomb structure carrying wave absorbing material
By placing the structure, the cell heated by microwave
The heat of the lamic structure can be transferred to the filter
Together with the air required for particulate combustion
The particulates to the flammable temperature.
Temperature in a very short time,
More efficient combustion of particulates at the end face
Can be done.

The filter and the filter are arranged in front of the filter.
Radio wave absorbing material for ceramic structure with honeycomb structure
Carrying the filter, the microwave of the filter itself
Efficient heating and microwave
Heated ceramic structure burns particulates
Can heat the air required for
Raising the rate to the combustible temperature in a shorter time
And particulates on the end face of the filter
Can be more efficiently burned.

Further, zinc, copper,
Metal oxides of manganese, cobalt, iron, tin, titanium,
Composite metal oxide and charcoal having perovskite crystal structure
Silicon nitride has excellent microwave absorption properties,
By using at least one of these, there is a filter
There is Ki is possible to improve the heating rate of the honeycomb structure
You.

[0025]

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

In FIG. 1, reference numeral 16 denotes an exhaust pipe for discharging exhaust gas of an internal combustion engine, 17 denotes a heating chamber provided in the middle of the exhaust pipe, and 18 denotes a heating chamber which is housed in the heating chamber and passes through the exhaust gas while the exhaust gas passes. Is a filter that collects the particulates contained in the honeycomb structure, and is formed of a honeycomb structure made of a porous ceramic material such as mullite and cordierite. 1
9 is a microwave generating means for generating a microwave for supplying power to the heating chamber, 20 is a waveguide for transmitting microwaves generated from the microwave generating means to the heating chamber, and 21 is an air supply means for supplying air to the heating chamber. It is. This air supply means 2
Reference numeral 1 denotes an air supply source 22 composed of a blower or a pump, an air guide pipe 23 for guiding the air to a heating chamber, and an air supply flow control valve 24 for controlling the flow of air in the air guide pipe. The exhaust gas flows in the exhaust pipe from the direction indicated by the arrow in the figure. 25 is a bypass pipe provided between the exhaust gas inflow side and the outflow side of the filter, 26 is an exhaust pipe flow control valve for controlling the flow rate of exhaust gas flowing through the heating chamber,
Reference numeral 27 denotes a bypass pipe flow control valve for controlling the flow rate of exhaust gas flowing in the bypass pipe. Reference numeral 28 denotes a heat insulating material provided between the outer periphery of the filter and the inner wall of the heating chamber, and the filter and the heating chamber are arranged substantially concentrically.

FIG. 2 schematically shows a state in which the microwave absorbing material of the present invention is supported on a filter or a ceramic structure having a honeycomb structure without a filter function, which is disposed on the front surface of the filter on the exhaust gas inflow side. It is something that was expressed. In FIG. 2, reference numeral 29 denotes the above-mentioned radio wave absorbing material, which is a metal oxide of zinc, copper, manganese, cobalt, iron, tin, titanium, a composite metal oxide having a perovskite crystal structure, or silicon carbide. It is composed of at least one kind.

The flow of the exhaust gas, the process of collecting particulates, and the regeneration process in the filter regeneration device having such a configuration will be described below.

Normally, exhaust gas exhausted from the internal combustion engine flows into the filter 18 through the exhaust pipe 16. At this time, the particulates in the exhaust gas are collected on the wall of the filter, and the exhaust gas not containing the particulates is exhausted from the exhaust pipe 16.
And released to the atmosphere.

If the filter continues to collect particulates, the filter will be clogged, so that the filter must be regenerated at an appropriate time. At this time, for example, pressure detection means are provided in the exhaust pipes 16 on the inflow side and the outflow side of the heating chamber 17, and the timing at which the pressure loss of the filter obtained from this signal reaches a preset pressure reference value or the operation of the internal combustion engine Determined by time.

At the appropriate time, the valves 26, 27
Is controlled, and the exhaust gas is guided to the bypass pipe 25 and discharged to the atmosphere. Thereafter, the regeneration of the filter 18 is started. When a reproduction start instruction is issued, the microwave generation means 19 starts operating according to the instruction. The microwave generated by the microwave generating means is fed through the waveguide 20 into the heating chamber 17 containing the filter. The fed microwave is absorbed by the radio wave absorbing material 29 carried on the filter, and the filter and the particulates are heated by heat exchange.

Oxygen is required for the burning of the particulates, but the particulates are steamed before the air is introduced into the heating chamber. Thereafter, the air supply means 21 is operated to flow predetermined air into the heating chamber. The particulates, which have become hot due to this air, immediately transition to the combustion state. This combustion state moves behind the filter with microwave heating.

The completion of the regeneration is determined by a predetermined time, a method of determining when the pressure loss of the filter has reached a predetermined level, or a change pattern of a signal of a temperature detecting means provided behind the filter (for example, (The peak time of the exhaust gas temperature).

When the regeneration is completed based on the method described above, the valves 26 and 27 are controlled, the exhaust gas flows into the filter, and the operation shifts to the operation of collecting the particulates in the exhaust gas again. When the filter reaches the collection limit, the above-described series of operations is performed. Then, this cycle is repeated.

Next, a specific operation of the radio wave absorbing material 29 carried on the filter in the process of regenerating the particulate matter collected by the filter will be described.

The radio wave absorbing material carried on the filter is selected from those having a higher microwave absorbing power than the filter material and the particulates collected by the filter. Specific examples include metal oxides of zinc, copper, manganese, cobalt, iron, tin, and titanium, composite metal oxides having a perovskite-type crystal structure such as barium titanate, and silicon carbide. At least one type of material is supported. The radio wave absorbing material is carried on the wall surface of a filter or a porous ceramic honeycomb structure having no filter function.For example, a solution containing fine particles of the radio wave absorbing material is carried by a method such as immersion or spraying, and dried and fired. Can be obtained by Note that a binder such as alumina sol may be used to improve the adhesion to the filter.

When the amount of particulates collected by the filter reaches a predetermined amount, microwaves are supplied to the heating chamber. The supplied microwave is selectively absorbed by a radio wave absorbing material carried on the filter, and is converted into heat energy, thereby heating the filter and the particulate. At this time, since the radio wave absorbing material has high microwave absorption efficiency, the amount converted into heat energy also increases. Therefore, the particulates collected by the filter reach the combustible temperature in a short time. As a result, the power supply time of the microwave required for raising the temperature of the particulates to the combustible temperature range can be reduced.

Further, air required for combustion is blown after a predetermined time has elapsed for burning the particulates. The air is blown by the air supply means 21. At this time, the filter end face on the exhaust gas inflow side is cooled by air blowing, but the radio wave absorbing material present on the filter end face functions as a heating element by absorbing microwaves, thereby preventing the temperature of particulates from lowering. Thus, the particulates collected near the end face can be burned.

Further, the unburned particulates are heated not only by the combustion heat of the particulates which have started burning but also by the heat generated by the radio wave absorbing material, so that the temperature of the particulates over the entire area of the filter can be raised in a short time. At the same time, since the particulates on the end face of the filter burn as described above, air required for combustion can be diffused throughout the filter, so that the particulates over the entire filter can be burned. As a result, the time until the regeneration of the filter is completed can be shortened, and the temperature difference of the entire filter can be reduced, thereby preventing the filter from cracking due to a thermal factor.

FIG. 3 shows another embodiment of the present invention. The difference from the above-described embodiment is that a honeycomb structure having no filter function (a particulate trapping effect) is provided on the front surface of a filter 18 on the exhaust gas inflow side. That is, the ceramic structure 30 is disposed.

By arranging the ceramic structure 30, the cooling of the filter 18 by the air blown to burn the particulates is suppressed, and the temperature of the particulates heated and raised by the microwaves is prevented from lowering. In addition, heat dissipation from the filter 18 is prevented by the heat insulating effect, and the heating efficiency is further increased. As a result, it is possible to further reduce the microwave power supply time required to raise the particulates to the combustible temperature, and to more efficiently burn and regenerate the particulates present at the end face of the filter. Time to completion can be reduced.

In the structure of FIG. 3, a radio wave absorbing material is carried on a ceramic structure having a honeycomb structure without a filter function, which is disposed in front of the filter on the exhaust gas inflow side. Since the air required for the combustion of the curate can be preheated, it is possible to prevent the temperature at the filter end face and inside the filter from lowering.

In the above structure, the above-described effect can be further improved by supporting the radio wave absorbing material not only on the ceramic structure having no filter function disposed on the front surface of the filter on the exhaust gas inflow side but also on the filter. it can.

[0044]

As described above, the filter regeneration device for an internal combustion engine according to the present invention has the following advantages.

(1) Since a radio wave absorbing material having high microwave absorption efficiency is carried on the wall surface of the filter, the power supply time of the microwave required for raising the temperature of the particulates to a combustible temperature can be reduced. As a result, it is possible to easily realize that the power source for driving the microwave generating means is supplied from the vehicle power source and to maintain the durability of the vehicle power source.

(2) Even if the filter end face on the exhaust gas inflow side is cooled by the blowing of air for combustion, the particulate matter collected on the filter end face by the heat generation action due to the microwave absorption of the radio wave absorbing material. Since the temperature drop is prevented, the burning area of the particulates at the end face of the filter can be expanded, the regeneration rate of the filter is improved, and the particulate trapping effect that is always stable for long-term use can be obtained.

(3) As described above, the particulates at the end face of the filter can be burned, so that the air required for combustion can be diffused throughout the filter, and the particulates over the entire filter can be burned. As a result, the time required for the regeneration of the filter to be completed can be reduced, and the temperature difference of the entire filter can be reduced to prevent the filter from cracking due to thermal factors. In addition, a filter regeneration device having excellent durability can be obtained.

(4) By disposing a ceramic structure having a honeycomb structure without a filter function in front of the filter on the exhaust gas inflow side, cooling of the filter by air blown to burn particulates is suppressed, and The wave prevents the particulates heated and heated from lowering in temperature. In addition, heat dissipation from the filter is prevented by the heat insulating effect, and the heating efficiency is increased. As a result, the microwave power supply time required to raise the particulates to the combustible temperature range can be further reduced, and the particulates present at the end face of the filter are more efficiently burned, and regeneration is completed. Time until

(5) By disposing a ceramic structure having a honeycomb structure without a filter function carrying a radio wave absorbing material on the front surface of the filter on the exhaust gas inflow side, not only the above-mentioned heat insulating effect but also the air necessary for combustion can be obtained. Since the preheating can be performed, the effect of preventing a decrease in the temperature of the filter end surface and the inside of the filter is improved, and the time for raising the temperature of the particulates is further reduced.

[Brief description of the 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 cross-sectional view of a filter according to one embodiment of the present invention.

FIG. 3 is a configuration diagram of a filter regeneration device for an internal combustion engine according to another embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional filter regeneration device for an internal combustion engine.

[Explanation of symbols]

 Reference Signs List 16 exhaust pipe 17 heating chamber 18 filter 19 microwave generating means 20 waveguide 21 air supply means 22 air supply source 23 air guide pipe 24 air supply flow control valve 25 bypass pipe 26 exhaust pipe flow control valve 27 bypass pipe flow control valve 29 Radio wave absorption material 30 Ceramic structure (without filter function)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-279715 (JP, A) JP-A-3-210016 (JP, A) JP-A-59-2810 (JP, A) JP-A-58-58 174216 (JP, A) JP-A-64-87816 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01N 3/02 301-341

Claims (4)

(57) [Claims] A heating chamber provided in an exhaust pipe for exhausting exhaust gas of the internal combustion engine; a filter housed in the heating chamber for collecting particulates contained in the exhaust gas of the internal combustion engine; A ceramic structure having a honeycomb structure without a filter function, disposed on the front surface on the exhaust gas inflow side , a microwave generating means for generating microwaves for supplying power to the heating chamber, and a blower for supplying air to the heating chamber And a filter regeneration device for an internal combustion engine, wherein the filter carries a radio wave absorbing material for absorbing the microwave. 2. A heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, a filter housed in the heating chamber and collecting particulates contained in exhaust gas of the internal combustion engine, and the filter. A ceramic structure having a honeycomb structure without a filter function, disposed on the front surface on the exhaust gas inflow side , a microwave generating means for generating microwaves for supplying power to the heating chamber, and a blower for supplying air to the heating chamber And a filter regeneration device for an internal combustion engine, wherein the ceramic structure carries a radio wave absorbing material for absorbing the microwave. 3. A heating chamber provided in an exhaust pipe for exhausting exhaust gas of an internal combustion engine, a filter housed in the heating chamber and collecting particulates contained in exhaust gas of the internal combustion engine, and the filter A ceramic structure having a honeycomb structure without a filter function, disposed on the front surface on the exhaust gas inflow side , a microwave generating means for generating microwaves for supplying power to the heating chamber, and a blower for supplying air to the heating chamber And a filter regeneration device for an internal combustion engine, wherein the filter or the ceramic structure carries a radio wave absorbing material for absorbing the microwave. 4. A radio wave absorbing material zinc, copper, manganese, cobalt, iron, tin, metal oxides titanium, composite metal oxide having a perovskite crystal structure, claims 1 consisting of at least one silicon carbide The filter regeneration device for an internal combustion engine according to claim 3.