JP2819849B2 - 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 In recent years, regulations on the emission of air pollutants have been tightened in countries around the world for fixed sources such as cogeneration 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.

[0003] Among automobiles, diesel cars are in the process of tightening regulations on emission of particulates as well as nitrogen oxides. It is said that it is impossible to achieve the exhaust gas regulation value only by reduction measures by improving combustion such as fuel injection timing delay, and at present, it is indispensable to provide a post-treatment device for purifying exhaust gas. As a post-treatment device of a diesel engine, a method of using a filter for collecting particulates mainly composed of black smoke contained in an exhaust gas stream has been studied.

[0004] It is known that particulates burn at about 600 ° C. As a heating means for raising the temperature of the particulates to this temperature, a burner method, an electric heater method, a microwave method, or the like is considered.

FIG. 2 shows a filter regenerating apparatus in which a heating means uses a microwave system (for example, Japanese Patent Laid-Open No. 59-1260).
No. 22). 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. A waveguide for guiding the generated microwaves to the heating chamber; 9 a microwave reflecting plate;
Reference numeral 0 denotes an air pump, 11 denotes an air supply path, 12 denotes a drive power source for microwave generation means, 13 denotes a muffler, 14 denotes an air switching valve, and 15 denotes an exhaust gas switching valve. The filter 5 housed in the heating chamber 6 in this filter regeneration device has a configuration in which the exhaust gas inflow side and the exhaust gas outflow side of the filter 5 are arranged horizontally with respect to the road surface of the vehicle.

In the above configuration, the exhaust gas of the engine is guided to the filter 5 by the exhaust gas switching valve 15 or directly discharged to the atmosphere. In the particulate collection process, the exhaust gas is guided to the filter 5 and the particulates contained in the exhaust gas are collected by the filter 5. When the trapping capacity reaches the limit, the exhaust gas switching valve 15 is controlled to shut off the exhaust gas to the exhaust pipe 3, and all 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 process, the energy for heating the particulates is supplied from the microwave generating means 7 and the air required for combustion is supplied from the air pump 10. When the regeneration of the filter is completed after a predetermined time, the exhaust gas switching valve 15 is controlled again, the exhaust gas is guided to the filter 5, and the collection is started. This collection and regeneration process is repeated.

As the filter 5 of the above-mentioned filter regenerating apparatus, a honeycomb structure having a large number of through holes formed by partition walls made of a porous ceramic such as cordierite or mullite is used. The honeycomb structure is provided with sealing plugs having airtightness alternately at both ends of the through-hole so that an exhaust gas flow is discharged through a porous ceramic partition wall. It is collected on the porous ceramic partition wall on the inlet side.

[0009]

The particle diameter of the particulates collected by the filter in the filter collecting process having the above-described structure varies widely from several tens of nm to several tens of μm, and has a particle diameter of several tens of μm. If the particulates continue to adhere to the end face on the exhaust gas inflow side of the filter, the opening of the filter will be closed, and the trapping performance of the filter will be significantly reduced. This reduction in trapping performance causes a problem that the pressure loss of the exhaust gas is increased and the engine output is reduced, or the engine stops, and the trapping time is shortened.

On the other hand, the particulates collected by the filter during the filter regeneration process are heated by microwave heating means, and air required for combustion is blown. As described above, the opening of the filter is formed by the particulates. When the air is blocked, the diffusion of air required for combustion deteriorates, and a portion where particulate combustion does not occur occurs. As a result, there has been a problem that the regenerating performance of the filter is reduced and the collecting performance and the regenerating performance are gradually reduced in the continuous repetition of collecting and regenerating particulates.

The present invention solves the above-mentioned problems, and suppresses blockage of a filter opening due to accumulation of particulates on an end face of a filter, improves collection performance, and continuously improves collection and regeneration performance as a filter. It is an object of the present invention to provide a reproducing apparatus capable of maintaining the reproduction speed.

[0012]

To achieve the above object, a filter regeneration device for an internal combustion engine according to the present invention is provided with 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. A filter for collecting particulates contained in exhaust gas of the internal combustion engine, arranged so that an exhaust gas inflow side is located lower than an exhaust gas outflow side with respect to a road surface of the vehicle; Centrifugal force dust collecting means connected to an exhaust pipe through which exhaust gas is provided, provided between the exhaust pipe on the side where gas flows into the filter, and microwave generating means for generating microwaves for supplying power to the heating chamber And a blower for supplying air to the heating chamber.

Further, the present invention is configured such that the filter carries a catalyst for decomposing particulates at a low temperature or a radio wave absorbing material having a high microwave absorptivity.

[0014]

According to the above construction, when the particulates contained in the exhaust gas discharged from the diesel engine in the particulate collection process flow into the centrifugal dust collecting means composed of a cyclone, the particulates having a large particle size and a small particle size due to the centrifugal force. Separated into things. At this time, the particulates having a large particle diameter fall to the lower portion of the centrifugal dust collecting means due to gravity and accumulate, and the particulates having a small particle diameter are raised by the centrifugal dust collecting means together with the exhaust gas to house the filter. Is discharged to the heating chamber and collected by a filter. Since the trapped particulates have a small particle size, the blocking of the filter opening can be suppressed, and the trapping function does not deteriorate even after long use.

On the other hand, the particulates collected by the filter in the filter regeneration process are heated by microwave heating means, and air required for combustion is blown. As described above, the opening of the filter is formed by the particulates. Since the air is not blocked, the air easily diffuses into the filter, and the burning of the particulates starts smoothly. And this combustion heat is efficiently transmitted to the rear of the filter by the ascending airflow because the filter is disposed so that the exhaust gas inflow side of the filter is located lower than the exhaust gas outflow side with respect to the road surface of the vehicle. Particulates throughout the filter can be burned.

Further, according to the present invention, by supporting a catalyst for decomposing particulates at a low temperature on the filter for an internal combustion engine, the particulates can be burned at a low temperature, so that the particulates deposited on the filter can be efficiently burned. Can be removed. In addition, by supporting a radio wave absorbing material having a high microwave absorptivity instead of the catalyst, heating of the filter end face is promoted, so that particulates deposited on the filter can be efficiently burned and removed.

[0017]

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 exhausting exhaust gas from 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 while the exhaust gas passes therethrough. 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. The filter 18 is arranged such that the exhaust gas inflow side is located below the exhaust gas outflow side. Reference numeral 19 denotes a centrifugal dust collecting means such as a cyclone. An exhaust pipe 16 on the side where the exhaust gas from the heating chamber flows into the filter 18 is tangentially connected to the upper part of the cylinder of the centrifugal dust collecting means 19. Is disposed between the exhaust pipe 16 and the heating chamber 17 on the exhaust gas inflow side. Reference numeral 20 denotes microwave generating means for generating microwaves for supplying power to the heating chamber, 21 denotes a waveguide for transmitting microwaves generated from the microwave generating means to the heating chamber, and 22 denotes air supply means for supplying air to the heating chamber. It is. The air supply means 22 includes an air supply source 23 composed of a blower or a pump, an air guide pipe 24 for guiding the air to the heating chamber, and an air supply flow control valve 25 for controlling the flow of air in the air guide pipe. I have. The exhaust gas flows in the exhaust pipe from the direction indicated by the arrow in the figure. 26 is a bypass pipe provided between the exhaust gas inflow side and the outflow side of the filter, 27 is an exhaust pipe flow control valve for controlling the flow rate of exhaust gas flowing through the heating chamber, and 28 is a bypass for controlling the flow rate of exhaust gas flowing in the bypass pipe. This is a pipe flow control valve.
Reference numeral 29 denotes a heat insulating material provided between the outer wall of the filter and the wall of the heating chamber, and the filter and the heating chamber are arranged substantially concentrically.

The flow of the exhaust gas, the particulate trapping process, and the regeneration process in the filter regeneration device having the above-described configuration will be described below.

Normally, the exhaust gas exhausted from the internal combustion engine passes through the exhaust pipe 16 and flows into the filter 18 via the centrifugal dust collecting means 19. At this time, the particulates in the exhaust gas are collected on the wall surface of the filter, and the exhaust gas not containing the particulates is discharged to the atmosphere through the exhaust pipe 16.

If the filter 18 continues to collect particulates, the filter 18 becomes clogged. Therefore, the filter 18 must be regenerated at an appropriate time. At this time, for example, pressure detection means is provided in the exhaust pipes 16 on the inflow side and the outflow side of the heating chamber 17, and the filter
Is determined based on the timing at which the pressure loss reaches a preset pressure reference value and the operating time of the internal combustion engine.

The exhaust gas containing particulates discharged from the diesel engine in the above-described collection process flows tangentially from the upper part of the cylinder of the centrifugal dust collecting means 19 composed of a cyclone to which the exhaust pipe 16 is connected. This exhaust gas descends while rotating along the inner wall of the cylinder, reverses from the lower part of the cone, rises while rotating and rises to the centrifugal force dust collecting means 1.
It is discharged from 9. At this time, the particulates having a large particle diameter move toward the wall due to the centrifugal force generated by the swirling of the air flow, fall along the wall surface due to gravity, and accumulate on the lower portion of the centrifugal dust collecting means 19. On the other hand, the particulates having a small particle diameter are guided to the filter 18 together with the exhaust gas, and only the particulates are collected. Since the collected particulates have a small particle diameter, they can efficiently enter the inside of the filter 18 through the opening, and the filter 18
Can be prevented from being blocked. Therefore, the trapping function of particulates can be improved, and the drop in the trapping function can be prevented over a long period of use.

On the other hand, when the collection of the filter 18 reaches an appropriate time, the valves 27 and 28 are operated, the exhaust gas is guided to the bypass pipe 26 and discharged to the atmosphere, and the regeneration of the filter 18 is started. When a reproduction start instruction is issued, the microwave generation means 20 starts operating according to the instruction. The microwave generated by the microwave generating means 20 is supplied to the heating chamber 17 containing the filter 18 through the waveguide 21, and the particulates collected on the wall of the filter 18 by the microwave are removed. Heated. Thereafter, the air supply means 22 is operated to flow predetermined air into the heating chamber 17. The particulates, which have become hot due to this air, immediately transition to the combustion state. This combustion state moves toward the exhaust gas outflow side of the filter 18.

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 the signal of the temperature detecting means provided behind the filter (see FIG. For example, it is identified by a method that is determined based on the exhaust gas temperature peak time).

When the regeneration is completed based on the method described above, the valves 27 and 28 are controlled so that 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.

The particulates collected by the filter 18 in the regeneration process are heated by microwave heating means, and the air required for combustion is blown. As described above, the opening of the filter 18 has a centrifugal force. Occlusion by particulates can be suppressed by the effect of the dust collecting means 19. Therefore, the air required for combustion easily diffuses into the filter 18, and the burning of the particulates starts smoothly. Since the filter 18 is disposed such that the exhaust gas inflow side of the filter is positioned lower than the exhaust gas outflow side with respect to the traveling road surface of the vehicle, the combustion heat is transferred to the particulates behind the filter 18 by the upward airflow. It is transmitted efficiently, and the particulates in the entire area of the filter can be burned. As a result, excellent reproduction performance can be realized, and a decrease in collection performance and reproduction performance can be prevented in continuous repetition of particulate collection and reproduction.

Further, by supporting a catalyst for decomposing particulates at a low temperature on the filter 18 for an internal combustion engine of the present invention, the particulates can be burned at a low temperature, and the regeneration performance of the particulates deposited on the filter can be improved. It can be further improved. As a catalyst for decomposing the particulates at a low temperature, alkali metals, carbonates and vanadiums composed of alkaline earth metals, molybdenum,
Oxides of tungsten, copper, manganese, and cobalt are listed, and at least one of them is supported on the filter 18.

In addition, by supporting a radio wave absorbing material having a high microwave absorptivity instead of the above catalyst, the filter can be efficiently heated, so that the regenerating performance of the particulates deposited on the filter can be further improved. .
Examples of the radio wave absorbing material include zinc, copper, manganese, cobalt, iron, tin, oxides of titanium, composite metal oxides having a perovskite crystal structure, and silicon carbide.
At least one of these is carried by the filter 18.

The particulates having a large particle size deposited on the lower part of the centrifugal dust collecting means 19 are periodically taken out from the lower part of the centrifugal dust collecting means 19, or may be removed from the lower part of the centrifugal dust collecting means 19. The part can be periodically burned and removed using a heating means such as an electric heater or a microwave.

In this embodiment, the heating of the particulates is performed by heating means using microwaves. However, the present invention is not limited to this, and heating means such as an electric heater can be applied.

[0031]

As described above, according to the filter regeneration device for an internal combustion engine of the present invention, the following effects can be obtained.

The filter regeneration device for an internal combustion engine according to the present invention has a configuration in which the centrifugal force dust collecting means and the filter are arranged such that the exhaust gas inflow side of the filter is located lower than the exhaust gas outflow side with respect to the road surface of the vehicle. (1) In the particulate collection process, particulates having a large particle size are removed, and only particulates having a small particle size are collected by a filter by ascending the centrifugal dust collecting means together with the exhaust gas. Therefore, it is possible to prevent the filter from closing the opening of the filter due to the collected particulates, thereby improving the collection performance and suppressing the deterioration of the collection function during long-term use. (2) In the process of regenerating particulates, the particulates collected by the filter easily diffuse into the filter because the opening of the filter is not closed by the particulates as described above. Curate combustion can be started smoothly, and this combustion heat can be efficiently transmitted to the rear of the filter by using the ascending airflow, so that particulates in the entire area of the filter can be burned. Therefore, excellent reproduction performance can be realized, and a decrease in collection performance and reproduction performance can be prevented in continuous repetition of particulate collection and reproduction. (3) Since the exhaust gas is discharged from the bypass pipe via the centrifugal dust collecting means while the filter is being regenerated, the amount of particulates in the exhaust gas discharged to the atmosphere can be reduced. (4) Further, by supporting the catalyst for decomposing particulates at a low temperature on the filter for an internal combustion engine of the present invention, the particulates can be burned at a low temperature, so that the regeneration performance of the particulates deposited on the filter can be improved. Can be improved. (5) Since the filter can be efficiently heated by supporting a radio wave absorbing material having a high microwave absorptivity instead of the catalyst, the regeneration performance of the particulates deposited on the filter can be further improved. .

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a conventional filter regeneration device for purifying exhaust gas of an internal combustion engine.

[Explanation of symbols]

 Reference Signs List 16 exhaust pipe 17 heating chamber 18 filter 19 centrifugal force dust collecting means 20 microwave generating means 21 waveguide 22 air supply means 23 air supply source 24 air guide pipe 25 air supply flow control valve 26 bypass pipe 27 exhaust pipe flow control valve 28 Bypass pipe flow control valve

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-137424 (JP, A) JP-A-59-126022 (JP, A) JP-A-60-137413 (JP, A) JP-A-4- 171212 (JP, A) JP-A 1-125812 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F01N 3/02 301-341

Claims (3)

(57) [Claims] 1. A heating chamber provided in an exhaust pipe for exhausting exhaust gas of an internal combustion engine, and an exhaust gas inflow side accommodated in the heating chamber is positioned lower than an exhaust gas outflow side with respect to a traveling road surface of a vehicle. And a centrifugal force collector provided between the heating chamber and an exhaust pipe on the side where the exhaust gas flows into the filter, the filter being configured to collect the particulates contained in the exhaust gas of the internal combustion engine. A filter regeneration device for an internal combustion engine, comprising: dust means; microwave generation means for generating microwaves for supplying power to a heating chamber; and blowing means for supplying air to the heating chamber. 2. A filter regeneration device for an internal combustion engine according to claim 1, wherein the filter carries a catalyst for decomposing particulates contained in the exhaust gas stream at a low temperature. 3. The filter regeneration device for an internal combustion engine according to claim 1, wherein the filter carries a radio wave absorbing material having a high microwave absorptivity.