JP2893985B2 - 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.

However, if the particulates continue to be collected, the filter will be clogged and the collection capacity will be greatly reduced, and the flow of exhaust gas will be poor, reducing the engine output or stopping the engine. Cause such problems.

[0005] Therefore, although technology development for regenerating the trapping ability of the filter is currently being promoted worldwide, it has not yet been put to practical use.

[0006] 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. 3 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 the 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 filter regenerating apparatus, a honeycomb structure having a large number of through holes formed by partition walls made of 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.

[0011]

The particulates collected by the filter in the filter regeneration process having the above-described structure are heated by microwave heating means, and the combustion is started by blowing air necessary for combustion. . At this time, the filter end face on the inflow side of the exhaust gas is cooled by the blowing of air necessary for combustion, so that the temperature rise of the particulates is prevented, and it is difficult to regenerate the filter end face. As a result, during the continuous repetition of collection and regeneration of particulates, the particulates accumulate on the end face of the filter, blocking the through-holes, losing the ability to collect as a filter, and deteriorating the collecting and regenerating performance. There was a problem to do.

On the other hand, it takes a lot of time to raise the particulates at the end face of the filter to a combustible temperature, and it is necessary to supply power for driving the microwave generation source from a power source mounted on the vehicle. There was a problem that was practically difficult.

The present invention has been made to solve the above-mentioned problems, and can efficiently regenerate particulates at the end face of a filter, continuously maintain collection and regeneration performance as a filter, and burn the particulates at the end face of the filter. It is an object of the present invention to provide a reproducing apparatus capable of shortening the time required to raise the temperature and sufficiently supplying a drive power supply for a microwave generation source from a power supply mounted on an automobile.

[0014]

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 the exhaust gas of the internal combustion engine, and a microwave generating means for generating a microwave for supplying power to the heating chamber,
And a blower for supplying air to the heating chamber, wherein the filter is disposed such that an end face on an exhaust gas inflow side of the filter is positioned higher than an end face on an exhaust gas outflow side with respect to a traveling road surface of the vehicle. Configuration.

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.

[0016]

The filter of the filter regeneration device for an internal combustion engine that collects particulates is heated by a microwave heating means when the particulate collection reaches a predetermined amount, and the air required for combustion is further heated. Is blown. At this time, the end face of the filter on the exhaust gas inflow side is cooled by the air, and the temperature rise of the particulates is prevented.

[0017] However, an internal combustion engine filter of the present invention is configured to be positioned upwardly with respect to the traveling road surface of the car than the end face of the end face the exhaust gas outlet side of the exhaust gas flow inlet side of said filter since it has been heat transfer in the direction of the filter end face portion inside the heat is located above the updraft of the filter that is heated by microwave heating, burning of particulates trapped in the filter end face The time to reach the possible temperature is reduced. Further, even when the combustion starts inside the filter, the combustion heat is transferred to the upper end face of the filter by the ascending airflow, so that most of the particulates collected on the end face of the filter can be burned off. On the other hand, the filter blows air necessary for combustion from the exhaust gas inflow direction ,
Particulate combustion is detected by the exhaust gas
Can be combusted Runode can proceed in a direction, the particulate filter throughout high reproduction performance
Can be realized.

Further, according to the present invention, the particulates can be burned at a low temperature by supporting a catalyst for decomposing the particulates at a low temperature on the filter for an internal combustion engine, 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.

[0019]

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 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 accommodated 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 outside of the filter and the wall of the heating chamber, and the filter and the heating chamber are arranged substantially concentrically.

FIG. 2 shows an example in which the above-described filter regeneration device for an internal combustion engine of the present invention is mounted on an automobile. As shown in FIG. 2, the filter 18 housed in the heating chamber is arranged such that the end face on the exhaust gas inflow side is positioned higher than the end face on the exhaust gas outflow side with respect to the road surface of the vehicle. .

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.

The filter must be regenerated at an appropriate time because the filter will become clogged if particulates are continuously collected. 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 into the heating chamber 17 containing the filter through the waveguide 20, and the particulates collected on the wall of the filter are heated by the microwave. .

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 toward the exhaust gas outflow side of 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 the signal of the 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 above-described method, 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, the operation of the present invention in the process of regenerating the particulates collected by the filter will be described.

With the above-described apparatus configuration, when the collection of particulates of the filter reaches a predetermined collection amount, microwaves are supplied to the heating chamber, and the particulates collected by the filter are heated . Since the filter for the internal combustion engine in the present invention is arranged such that the end face on the exhaust gas inflow side of the filter is located higher than the end face on the exhaust gas outflow side with respect to the traveling road surface of the automobile, the microwave is used. The heat inside the filter, which has been heated by the heating of the filter, is transferred by the ascending airflow toward the filter end face located above . Due to this heat transfer, the cooling of the filter end face is suppressed, and the particulates collected on the filter end face can reach the combustible temperature and the time is shortened. Position upward by the combustion heat updraft In yet if combustion inside the filter is started
It is transmitted in the direction of the placed filter end face. Most of the particulates collected on the end face of the filter can be burned and removed by the transferred combustion heat. As a result, during the continuous repetition of the collection and regeneration of the particulates, the particulates are deposited on the end face of the filter, and the collection performance and the regeneration performance of the filter due to the blocking of the through-holes can be prevented from being reduced. Since the temperature of the particulates can be raised to the combustible temperature in a short time, the power supply for driving the microwave generation source can be supplied from the power supply mounted on the automobile.

On the other hand in the direction of flow of the exhaust gas in the filter can Rukoto allowed to proceed combustion outflow direction of the exhaust gas since the blowing air required for combustion from the inflow direction of the exhaust gas. Therefore, the particulates in the entire area of the filter can be burned, so that high regeneration performance can be realized.

Further, while the microwave is being supplied to the heating chamber, the blowing of the air required for combustion is stopped or the amount of the blowing is reduced, and all the particulates collected on the end face of the filter located above are removed by burning. After that, by increasing the air blowing amount, higher filter regeneration performance is realized.

Further, by supporting a 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, and the regeneration performance of the particulates deposited on the filter can be improved. Can be improved. Examples of the catalyst for decomposing the particulates at a low temperature include alkali metals, carbonates and vanadium composed of alkaline earth metals, molybdenum, tungsten, copper, manganese, and oxides of cobalt.
At least one of these is carried on the filter.

In addition, by supporting a radio wave absorbing material having a high microwave absorptivity instead of the above-mentioned 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 on the filter.

[0035]

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

In the filter regeneration device for an internal combustion engine according to the present invention, the filter is configured such that the exhaust gas inflow side of the filter is positioned higher than the exhaust gas outflow side with respect to the road surface of the vehicle. Heat inside the filter, which has been heated by microwave heating, is heat-transferred toward the end face by the rising airflow,
The particulates collected on the filter end face located above can be heated to a combustible temperature in a short time. Therefore it is possible to supply the supply of the drive power of the microwave source from a power source mounted on an automobile. (2) When the combustion starts inside the filter, the heat of combustion is transmitted to the filter end face located above by the ascending airflow, so that most of the particulates collected on the filter end face can be burned and removed. Accordingly, it is possible to prevent the particulates from accumulating on the end face of the filter during continuous repetition of the collection and regeneration of the particulates, thereby preventing the filter's collection performance and regeneration performance from being deteriorated due to the blocking of the through holes. (3) On the other hand the filter can and this <br/> to advance the <br/> burning of particulates in the exhaust gas outflow direction of the filter by blowing air required for combustion from the exhaust gas inflow direction Thus, the particulates in the entire area of the filter can be burned. Therefore, high reproduction performance can be realized. (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) The more the reproduction performance of the particulates deposited on the filter because it heats the filter efficiently by supporting the radio wave absorbing material absorption rate of the microwave have high <br/> instead of the catalyst Can be 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 in which a filter device for an internal combustion engine according to one embodiment of the present invention is mounted on an automobile.

FIG. 3 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 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

Continuation of the front page (56) References JP-A-59-126022 (JP, A) JP-A-4-279715 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01N 3 / 02 321

Claims (3)

(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 exhaust gas of the internal combustion engine; A microwave generating means for generating microwaves for supplying power to the chamber, and a blowing means for supplying air to the heating chamber, wherein the end face of the filter on the exhaust gas inflow side is larger than the end face of the filter on the exhaust gas outflow side. An internal combustion engine filter regeneration device configured to be located above a road surface of a vehicle. 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.