JPH04301122A - Filter renovator for internal combustion engine - Google Patents

Abstract

PURPOSE:To shorten the temperature rise time of particulates and the renovation time of a filter and renovate the whole area of the filter and the prevent the damage of the filter, concerning the filter reclaimer which heats the particulates collected in the exhaust gas of a diesel engine with microwaves. CONSTITUTION:A filter 18 for collecting particulates bears a wave absorbing material high in microwave absorption efficiency or that ceramic structure which has honey combs structure without a filter function being arranged on the inflow side of the exhaust gas of the filter bears said wave absorbing material. By the heating action by the microwave absorption of the said wave absorbing material, the particulates in all area of the filter can be heated to combustible temperature in a short time, so high reclamation ratio can be gotten. Moreover, the temperature distribution of the filter can be improved and the cracks can be prevented.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a device for regenerating an internal combustion engine filter that collects particulate matter contained in exhaust gas emitted from a diesel engine using microwave energy. It is.

0002

BACKGROUND OF THE INVENTION The high economic growth of so-called developed countries such as Europe, America and Japan has greatly contributed to civilization on earth. However, the waste of fossil fuel energy centered on economic growth in developed countries has polluted the earth's atmosphere.

[0003] Regarding global environmental conservation, countermeasures against global warming, that is, countermeasures for reducing CO2, are currently receiving a great deal of attention, but countermeasures against acid rain, which can lead to deforestation, cannot be ignored.

[0004] Acid rain is a natural phenomenon caused by air pollutants such as sulfur oxides and nitrogen oxides, and in recent years many countries around the world have been enforcing regulations on the emission of air pollutants.
There is a movement to strengthen this against stationary sources such as generation systems and mobile sources such as automobiles. In particular, regulations regarding automobile exhaust gas have been shifted from conventional concentration regulations to total volume regulations, and the regulatory values themselves have been significantly reduced.

[0005] Among automobiles, diesel cars are subject to stricter emission regulations for particulates as well as nitrogen oxides. It is said that it is impossible to achieve the exhaust gas regulation value only by conventional measures to reduce pollutants in exhaust gas by improving combustion such as delaying fuel injection timing, and it is currently essential to install an exhaust gas after-treatment device. This post-processing device has a filter that collects particulates.

However, if the particulates continue to be collected, the filter becomes clogged and its collection ability is significantly reduced, and the flow of exhaust gas becomes poor, resulting in a reduction in engine output or a stoppage of the engine.

[0007] Therefore, technological development is currently underway all over the world to regenerate the collection ability of filters.
It has not yet been put into practical use.

[0008] Particulates are known to burn at temperatures of about 600°C. As a means of generating energy to raise the temperature of particulates to this high temperature range,
A burner method, an electric heater method, a microwave method, etc. are being considered.

The present inventors have developed a filter regeneration device using a microwave method, taking into account factors such as good temperature raising efficiency, safety, ease of device configuration, and good regeneration controllability.

[0010] As a filter regeneration device using the microwave method, there is, for example, Japanese Patent Laid-Open No. 126022/1983. The device disclosed in the publication is shown in FIG. In the figure, 1 is an engine, 2 is an exhaust manifold, 3 is an exhaust pipe, 4 is an exhaust branch pipe, 5 is a filter, 6 is a heating chamber housing the filter, 7 is a microwave generator, and 8 is a microwave generator. 9 is a microwave reflecting plate, 10 is an air pump, 11 is a waveguide that guides the generated microwave to the heating chamber;
12 is an air supply path; 12 is a driving power source for 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 engine exhaust gas 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, exhaust gas is guided to the filter 5, and particulates contained in the exhaust gas are collected by the filter 5, but as described above, the collection capacity of the filter 5 is limited. When the collection capacity reaches its limit, the exhaust gas switching valve 15 is controlled, the exhaust gas to the exhaust pipe 3 is cut off, and all of the exhaust gas is discharged to the atmosphere via the exhaust branch pipe 4. During this time, the filter 5 is regenerated. In this filter regeneration cycle, energy for heating the particulates is supplied from the microwave generating means 7, and air necessary for combustion is simultaneously supplied from the air pump 10. When the filter regeneration is completed after a predetermined period of time, the exhaust gas switching valve 15 is controlled again to guide the exhaust gas to the filter 5. This cycle of collection and regeneration is repeated.

0012

[Problems to be Solved by the Invention] However, in the above-mentioned conventional configuration, the combustion air is flowed through the filter during the time when the temperature is raised to the temperature at which the particulates begin to burn. This requires a lot of time, and it is difficult and practical to supply the driving power for the microwave generation source from the power supply installed in the vehicle.

[0013] Furthermore, the combustion air acts to prevent the temperature of the particulates from rising and narrows the area where the particulates can be combusted, making it difficult to effectively regenerate the entire area of the filter. Particularly, it was difficult to burn particulates at the end face of the filter on the exhaust gas inflow side.

Furthermore, by narrowing the area where particulates can be combusted, the temperature difference across the entire filter becomes large, causing cracks to occur in the filter itself, resulting in a reduction in the filter's trapping effect.

[0015] The present invention solves the above-mentioned problems by shortening the time it takes to raise the temperature to the temperature at which particulates burn, making it possible to sufficiently supply driving power for the microwave generation source from the automobile power supply, and effectively increasing the entire area of the filter. The purpose is to provide a device that can prevent regeneration and damage to the filter.

[0016]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine, and a heating chamber provided in an exhaust pipe for discharging exhaust gas of an internal combustion engine; a filter for collecting particulates contained in the heating chamber; a microwave generating means for generating microwaves in the heating chamber; and a blowing means for blowing air into the heating chamber, and the filter absorbs the microwaves. The structure supports a radio wave absorbing material.

Further, the present invention has a configuration in which a ceramic structure having a honeycomb structure without a filter function is disposed on the front surface of the exhaust gas inflow side of the filter for collecting particulates carrying the radio wave absorbing material.

Further, the present invention has a structure in which a ceramic structure having a honeycomb structure and carrying the radio wave absorbing material and having no filter function is disposed on the front surface of the exhaust gas inflow side of the filter for collecting particulates.

The present invention also provides a ceramic structure having a honeycomb structure that carries the radio wave absorbing material and does not have a filter function, on the front surface of the exhaust gas inflow side of the filter that collects the particulates that carry the radio wave absorbing material. The structure is as follows.

[0020]

[Operation] According to the above-described structure, the microwave is supplied to the heating chamber when the amount of particulates collected by the filter reaches a predetermined amount. At this time, the radio wave absorbing material supported on the filter efficiently absorbs the supplied microwaves and converts them into heat, which allows the filter itself to increase in temperature faster, raising the temperature to the temperature at which the particulates can burn. It is possible to shorten the microwave power supply time required for

Furthermore, the end face of the filter on the exhaust gas inflow side is cooled because the air necessary for combustion of particulates is blown, but the above-mentioned radio wave absorbing material present on the end face of the filter effectively absorbs microwaves. Since the particulates are absorbed, a drop in the temperature of the end face of the filter is prevented, and the particulates collected on the end face of the filter can be heated to a combustible temperature and combusted.

Furthermore, unburned particulates are heated not only by the transfer of combustion heat from the particulates that have started burning, but also by the microwave absorption of the radio wave absorbing material, so that the temperature of the particulates in the entire area of the filter is raised in a short period of time. In addition, since it can be combusted, the temperature difference in the filter is reduced, and the generation of cracks in the filter due to thermal distortion is prevented.

Furthermore, by arranging a ceramic structure having a honeycomb structure in front of the filter on the exhaust gas inflow side, cooling by air necessary for combustion of particulates is suppressed, and the filter heated by microwaves is insulated. Therefore, the temperature of the particulates can be raised to a combustible temperature in a short time, and the particulates present on the end face of the filter can be more efficiently combusted.

Furthermore, by arranging a ceramic structure having a honeycomb structure supporting a radio wave absorbing material on the front surface of the filter on the exhaust gas inflow side, the heat of the ceramic structure heated by microwaves can be transferred to the filter. At the same time, it is possible to heat the air necessary for combustion of particulates, so the temperature of particulates can be raised to the combustible temperature in an extremely short time, and particulates existing on the end face of the filter can be combusted more efficiently. can be done.

[0025]

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

In FIG. 1, 16 is an exhaust pipe for discharging the exhaust gas of the internal combustion engine, 17 is a heating chamber provided in the middle of the exhaust pipe, and 18 is housed in the heating chamber, and the exhaust gas is heated while the exhaust gas is passing through. It is a filter that collects particulates contained in water, and is composed of a honeycomb structure made of porous ceramic material such as mullite or cordierite. 1
Reference numeral 9 denotes a microwave generation means for generating microwaves to supply electricity to the heating chamber, 20 a waveguide for transmitting the microwaves generated from the microwave generation means to the heating chamber, and 21 an air supply means for supplying air to the heating chamber. It is. This air supply means 2
1 is composed of an air supply source 22 consisting of a blower or a pump, an air guide pipe 23 that guides the air into the heating chamber, and an air supply flow rate control valve 24 that controls the flow of air within the air guide pipe. Exhaust gas flows through the exhaust pipe in the direction indicated by the arrow in the figure. 25 is a bypass pipe provided between the exhaust gas inflow side and the exhaust gas outflow side of the filter; 26 is an exhaust pipe flow rate control valve that controls the flow rate of exhaust gas flowing through the heating chamber;
27 is a bypass pipe flow rate control valve that controls the flow rate of exhaust gas flowing inside the bypass pipe. 28 is 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 radio wave absorbing material that absorbs microwaves of the present invention is carried on a filter or a ceramic structure having a honeycomb structure without a filter function and placed on the front surface of the exhaust gas inflow side of the filter. It is expressed in terms of In FIG. 2, 29 is the radio wave absorbing material described above, and this radio wave absorbing material is made of metal oxides of zinc, copper, manganese, cobalt, iron, tin, and titanium, composite metal oxides having a perovskite crystal structure, and silicon carbide. Consists of at least one type.

The flow of exhaust gas, the particulate collection process, and the regeneration process in the filter regeneration device having such a configuration will be explained below.

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

If the filter continues to collect particulates, it will become clogged, so 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 when the pressure loss of the filter obtained from this signal reaches a preset pressure reference value or the internal combustion engine operation is determined. judged by time.

At this appropriate time, the valves 26 and 27
is controlled, and the exhaust gas is guided to the bypass pipe 25 and released to the atmosphere. Thereafter, the filter 18 begins to regenerate. When a reproduction start instruction is issued, the microwave generating means 19 starts operating in accordance with this instruction. The microwave generated by this microwave generating means is fed through the waveguide 20 into the heating chamber 17 housing the filter. The supplied microwave is absorbed by the radio wave absorbing material 29 supported on the filter, and the filter and particulates are heated by heat exchange.

[0032] Oxygen is necessary for the particulates to burn, but the particulates are steamed before introducing the air into the heating chamber. Thereafter, the air supply means 21 is operated to cause a predetermined amount of air to flow into the heating chamber. The particulates, heated by this air, quickly move into a combustion state. This combustion state moves behind the filter with microwave heating.

The completion of regeneration can be determined by a predetermined time, by determining when the pressure loss of the filter reaches a predetermined level, or by determining the change pattern of the signal of the temperature detection means provided after the filter (for example, The identification method is determined based on the peak time of 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 collecting particulates in the exhaust gas again. When the filter reaches its collection limit, the series of operations described above are executed. And this cycle repeats.

Next, the specific action of the radio wave absorbing material 29 supported on the filter in the regeneration process of particulates collected on the filter will be explained.

[0036] The radio wave absorbing material supported on the filter is selected from a material that has a better ability to absorb microwaves than the filter material and the particulates collected on the filter. Specific examples include metal oxides of zinc, copper, manganese, cobalt, iron, tin, and titanium, complex metal oxides with a perovskite crystal structure such as barium titanate, and silicon carbide. At least one type of material is supported. The radio wave absorbing material is supported on the wall of a porous ceramic honeycomb structure that does not have a filter or a filter function. For example, a solution containing fine particles of the radio wave absorbing material may be supported by a method such as dipping or spraying, followed by drying and firing. can be obtained by Note that a binder such as alumina sol may be used to improve 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 microwaves are selectively absorbed by the radio wave absorbing material supported on the filter and converted into thermal energy, thereby heating the filter and the particulates. At this time, since the radio wave absorbing material has a high absorption efficiency of microwaves, a large amount of the microwaves is converted into thermal energy. Therefore, the particulates collected by the filter reach the combustible temperature in a short time. As a result, the microwave power supply time required to raise the temperature of the particulates to a combustible temperature range can be shortened.

Further, in order to burn the particulates, air necessary for combustion is blown after a predetermined time has elapsed. This air is blown by the air supply means 21. At this time, the end face of the filter on the exhaust gas inflow side is cooled by the blast of air, but the radio wave absorbing material present on the end face of the filter absorbs microwaves and functions as a heating element, preventing a drop in the temperature of the particulates. The particulates collected near the end face can be burned.

[0039] In addition, unburned particulates are heated not only by the transfer of the combustion heat of the particulates that have started burning, but also by the heat generated by the radio wave absorbing material, so the temperature of the particulates in the entire area of the filter can be raised in a short time. At the same time, as described above, by burning the particulates on the end face of the filter, the air necessary for combustion can be diffused over the entire area of the filter, thereby making it possible to burn the particulates over the entire area of the filter. As a result, the time required to complete regeneration of the filter can be shortened, and the temperature difference across the entire filter is reduced, making it possible to prevent cracks in the filter from occurring due to thermal factors.

FIG. 3 shows another embodiment of the present invention, which differs from the previous embodiment in that a honeycomb structure without a filter function (particulate collection effect) is provided on the front surface of the filter 18 on the exhaust gas inflow side. This is because the ceramic structure 30 having the above structure is disposed.

By arranging this ceramic structure 30, cooling of the filter 18 by the air blown to burn the particulates is suppressed, and a drop in temperature of the particulates heated by microwaves is prevented. In addition, the heat insulation effect prevents heat dissipation from the filter 18, resulting in higher heating efficiency. As a result, it is possible to further shorten the microwave power supply time required to raise the temperature of particulates to a combustible temperature, and to more efficiently burn and regenerate particulates present on the end face of the filter. The time to completion can be shortened.

In addition, in the configuration shown in FIG. 3, by supporting a radio wave absorbing material on the ceramic structure having a honeycomb structure without a filter function and disposed in front of the filter on the exhaust gas inflow side, it is possible to obtain not only the above-mentioned heat insulation effect but also the property Since the air necessary for burning the curate can be preheated, a drop in temperature at the end face of the filter and inside the filter can be prevented.

Furthermore, in the above structure, the above effect can be improved by supporting the radio wave absorbing material not only on the ceramic structure having no filter function, which is disposed in front of the filter on the exhaust gas inflow side, but also on the filter. can.

[0044]

As explained above, the internal combustion engine filter regeneration device of the present invention provides the following effects.

(1) Since the wall surface of the filter carries a radio wave absorbing material with high microwave absorption efficiency, the microwave power supply time required to raise the temperature of particulates to a combustible temperature can be shortened. As a result, it is possible to easily supply power for driving the microwave generating means from the automobile power source, and the durability of the automobile power source can be maintained.

(2) Even if the end face of the filter on the exhaust gas inflow side is cooled by blowing air for combustion, the particulates collected on the end face of the filter are Since a temperature drop is prevented, the particulate combustion area at the end face of the filter can be expanded, the regeneration rate of the filter is improved, and a stable particulate collection effect can be obtained over long periods of use.

(3) As described above, since the particulates on the end face of the filter can be combusted, the air necessary for combustion can be diffused over the entire area of the filter, making it possible to combust the particulates over the entire area of the filter. As a result, the time it takes to complete filter regeneration can be shortened, and the temperature difference across the entire filter is reduced, preventing cracks in the filter from occurring due to thermal factors, thus maintaining high regeneration effectiveness over a long period of time. , and a filter regeneration device with excellent durability can be obtained.

(4) By arranging 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 the air blown to burn particulates is suppressed, and micro Particulates heated by the waves are prevented from decreasing in temperature. Furthermore, the heat insulation effect prevents heat dissipation from the filter, increasing heating efficiency. As a result, the microwave power supply time required to raise the temperature of particulates to the combustible temperature range can be further shortened, and the particulates present on the end face of the filter can be more efficiently combusted, and regeneration can be completed. The time can be shortened.

(5) By arranging a ceramic structure having a honeycomb structure without a filter function and carrying a radio wave absorbing material on the front surface of the filter on the exhaust gas inflow side, not only the above-mentioned insulation effect but also the air necessary for combustion can be obtained. Since preheating can be performed, the effect of preventing a drop in temperature at the end face portion of the filter and inside the filter is improved, and the time required to heat up the particulates is further shortened.

[Brief explanation of drawings]

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

[Fig. 2] Partial cross-sectional view of a filter in one embodiment of the present invention.

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

[Figure 4] Configuration diagram of a conventional internal combustion engine filter regeneration device

[Explanation of symbols]

16 Exhaust pipe 17 Heating chamber 18 Filter 19 Microwave generation means 20 Waveguide 21 Air supply means 22 Air supply source 23 Wind 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 absorbing material

Claims (5)

[Claims] 1. A heating chamber provided in an exhaust pipe for discharging exhaust gas from an internal combustion engine; a filter housed in the heating chamber to collect particulates contained in the exhaust gas from the internal combustion engine; A filter regeneration for an internal combustion engine, comprising a microwave generating means for generating microwaves to supply electricity to a chamber, and a blower means for supplying air to the heating chamber, and the filter carries a radio wave absorbing material that absorbs the microwaves. Device. 2. A heating chamber provided in an exhaust pipe for discharging exhaust gas from an internal combustion engine; a filter housed in the heating chamber to collect particulates contained in the exhaust gas from the internal combustion engine; and a filter. a ceramic structure having a honeycomb structure without a filter function disposed on the front face of the exhaust gas inflow side; microwave generating means for generating microwaves to supply electricity to the heating chamber; and supplying air to the heating chamber. What is claimed is: 1. A filter regeneration device for an internal combustion engine, comprising: a blowing means; and the filter carries a radio wave absorbing material that absorbs the microwaves. 3. A heating chamber provided in an exhaust pipe for discharging exhaust gas from an internal combustion engine, a filter housed in the heating chamber and collecting particulates contained in the exhaust gas from the internal combustion engine, and the filter. a ceramic structure having a honeycomb structure without a filter function disposed on the front face of the exhaust gas inflow side; microwave generating means for generating microwaves to supply electricity to the heating chamber; and supplying air to the heating chamber. What is claimed is: 1. A filter regeneration device for an internal combustion engine, comprising: a blowing means; the ceramic structure carries a radio wave absorbing material that absorbs the microwaves. 4. A heating chamber provided in an exhaust pipe for discharging exhaust gas from an internal combustion engine, a filter housed in the heating chamber and collecting particulates contained in the exhaust gas from the internal combustion engine, and the filter. a ceramic structure having a honeycomb structure without a filter function disposed on the front face of the exhaust gas inflow side; microwave generating means for generating microwaves to supply electricity to the heating chamber; and supplying air to the heating chamber. What is claimed is: 1. A filter regeneration device for an internal combustion engine, comprising: a blowing means; the filter or the ceramic structure carries a radio wave absorbing material that absorbs the microwaves. 5. The radio wave absorbing material comprises at least one of metal oxides of zinc, copper, manganese, cobalt, iron, tin, and titanium, a composite metal oxide having a perovskite crystal structure, and silicon carbide. The filter regeneration device for an internal combustion engine according to claim 3.