JPH04298622A - Filter for internal combustion engine and filter regeneration device - Google Patents

Abstract

PURPOSE:To provide a filter for removing fine particles including carbon in exhaust gas of an internal combustion engine and a filter regeneration device which collects such fine particles in order to have uniform heat distribution in the filter in regenerating the filter to remove the fine particles deposited in the filter, and is excellent in regeneration efficiency as well as in reliability of continuously maintaining the collecting and regenerating performance. CONSTITUTION:An exhaust gas introducing pipe 11 which carries exhaust gas in a cavity 12 having a filter 13 therein is provided to protrude. At the protruding terminal end of the pipe 11 a radiation antenna 20 is arranged and small hole group 21 is formed on the outer circumference of the pipe 11. With such a constitution, exhaust gas flow in the cavity 12 is radially shaped, and the deposition distribution of fine particles in the filter 13 is controlled, thereby ensuring high efficiency regeneration and high reliability.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter and a filter regeneration device for removing particulates containing carbon from exhaust gas of an internal combustion engine.

0002

[Prior Art] Conventionally, filters for collecting particulates in the exhaust gas of internal combustion engines (particularly diesel engines) and devices for removing and regenerating particulates accumulated in the filters have been used to prevent air pollution and to protect the environment. In order to strive for conservation, various studies are being conducted as exhaust gas regulations become stricter year by year. Filters also come in foam types and monolithic types, depending on their configuration, and the heat source for regenerators is also based on oil burners, oil burners, etc.
In addition to electric heaters, ideas have been made to use microwaves, but these have not been put to practical use.

A conventional example (Japanese Unexamined Patent Publication No. 1-290910) using microwaves as a heat source will be described below with reference to FIG. In the same figure, 1 is the engine, 2 and 3 are TM01
A cylindrical cavity resonator in which P mode is excited, 4 a microwave radiation antenna, 5 a waveguide, 6 a microwave generating means, 7 a filter for collecting particulates on a porous ceramic partition wall, 8 a microwave radiation antenna; This is a switching valve for exhaust gas flow. In such a configuration, spaces 9 and 10 are provided between the filter, which is disposed approximately at the center of the cavity resonator in the tube axis direction, and both end faces of the cavity resonator, respectively.

The microwave generated by the microwave generating means 6 passes through the waveguide 5 and is fed to the cavity resonator 2 or 3 from the radiation antenna 4 which projects into the spaces 9 and 10. The particulates collected on the porous ceramic partition walls of the filter are dielectrically heated by the supplied microwaves, and when the temperature reaches about 600° C., they are ignited and burned, and the filter is regenerated.

[0005]

[Problem to be Solved by the Invention] However, in this configuration, microwaves are fed from a single microwave generating means 6 to the cavity resonator 2 from two locations via the waveguide 5 and the radiation antenna 4. Therefore, as the relative dielectric constant and dielectric loss tangent of the load change depending on the adhesion state of particulates on the filter 7 (including the reduction of particulates due to combustion), the equivalent dimensions of the cavity resonator 2 change and the TM01P mode is stabilized. I couldn't excite it.

Furthermore, since the central part of the front surface of the filter 7 is directly hit by the powerful exhaust gas flow when the engine 1 is running, more particulates are deposited on the outer periphery than on the outer periphery, and the microwave power applied during regeneration is concentrated on the outer periphery. The filter material suppresses heat dissipation, resulting in extremely high temperatures that can cause the filter to melt, and the difference in temperature between the center and outer periphery can cause thermal distortion and cracks, resulting in poor durability. Further, since the filter 7 is porous to filter particulate matter and has relatively low hardness, there is a risk that the front plug portion may be damaged due to uneven exhaust gas flow.

Therefore, the present invention collects the particulates so that the heat generated by the combustion of the particulates accumulated in the filter during regeneration is uniform in each part of the filter, and has a high heating efficiency that allows for reliable combustion in a short time. It is an object of the present invention to provide a highly reliable internal combustion engine filter and filter regeneration device that can continuously maintain regeneration ability.

[0008]

[Means for Solving the Problems] In order to achieve the object, the present invention provides a filter regeneration device for an internal combustion engine, which includes a filter for collecting particulates, a cavity for housing and holding the filter, and a cavity for directing exhaust gas to the cavity. an exhaust introduction pipe connected to the cavity to introduce the particulates into the filter, and a heat source that heats and burns particulates accumulated in the filter, the exhaust introduction pipe being provided at a position facing the filter, and the exhaust introduction pipe being connected to the cavity. The terminal end of the pipe is closed and the outer peripheral part is opened to supply the exhaust gas flow radially to the cavity.

[0009] Furthermore, the heat source for heating and burning the particulates is a microwave oscillator, and the terminal end of the exhaust introduction pipe is a radiation antenna connected to the tip of a coaxial line having the microwave oscillator and the exhaust introduction pipe as an outer conductor. The structure is such that it is closed.

Further, the heat source for heating and burning the particulates is a resistance heating element, and the terminal end of the exhaust gas introduction pipe is closed with an outer shell provided on the resistance heating element via an insulator.

[0011] Further, in a honeycomb structure having a large number of through holes formed by porous ceramic partition walls, one end of the through holes is closed with a first sealing plug having no pores for each adjacent partition, and the other end is closed with a first sealing plug having no pores. The through hole not provided with the first sealing plug is closed with a second sealing plug without pores, and the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is hollow.

[0012] Furthermore, the honeycomb structure has a structure in which the hollow in the center of the cross section perpendicular to the fluid passage direction is filled with porous ceramic.

[0013] Furthermore, the honeycomb structure has a structure in which the hollow space at the center of the cross section perpendicular to the fluid passage direction is filled with ceramic having no pores.

[0014]

[Operation] The internal combustion engine filter regeneration device of the present invention includes a filter for collecting particulates, a cavity for housing and holding the filter, and an exhaust gas introduction pipe connected to the cavity for introducing exhaust gas into the cavity. , a heat source for heating and burning particulates accumulated in the filter, and the exhaust introduction pipe is provided at a position facing the filter, and the terminal end of the exhaust introduction pipe is closed and the outer peripheral part is opened to exhaust air. Since the gas flow is configured to be supplied radially to the cavity, the exhaust gas flow is deflected by the exhaust introduction pipe and does not directly hit the front of the filter, preventing damage to the filter, and the adhesion distribution of particulates that accumulate on the filter is also concentrated in the center. Compared to this, the amount of heat is increased at the outer circumference, so the heat distribution of the filter during regeneration becomes uniform, improving regeneration efficiency and durability.

[0015] Furthermore, the heat source for heating and burning the particulates is a microwave oscillator, and the terminal end of the exhaust introduction pipe is a radiation antenna connected to the tip of a coaxial line having the microwave oscillator and the exhaust introduction pipe as an outer conductor. Since it is configured to be closed, the microwave transmission line can be constructed from existing members, and a microwave radiation antenna is provided at a position facing the filter, making it possible to effectively absorb microwaves into the particulates within the filter. .

Furthermore, since the heat source for heating and burning the particulates is a resistance heating element, and the terminal end of the exhaust gas introduction pipe is closed with an outer shell provided to the resistance heating element through an insulator, the resistance heating Since the body is not directly exposed to exhaust gas, durability is increased, and since a resistance heating element of any shape can be placed at a position facing the filter, particulates can be effectively heated and regeneration efficiency is improved.

[0017] Further, in a honeycomb structure having a large number of through holes formed by porous ceramic partition walls, one end of the through holes is closed with a first sealing plug having no pores for each adjacent partition, and the other end is closed with a first sealing plug having no pores. The through hole where the first sealing plug is not provided is closed with a second sealing plug without pores, and the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is hollow, Thermal stress during filter regeneration is dispersed between the hollow part and the outer periphery, reducing thermal distortion, increasing thermal strength, and improving durability.

[0018] Furthermore, since the hollow in the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with porous ceramic, it can be formed of the same material as the honeycomb structure, and the filter function can also be applied to this part. Because of this, the combustion air during regeneration is sufficiently diffused and the particulates are combusted, improving the regeneration rate. In addition, since it also has a filter function, mechanical strength and durability are improved with a relatively small increase in pressure loss.

[0019] Furthermore, since the hollow in the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with ceramic without pores, the filling can be done at the same time as the plugging, and the mechanical strength of the filter can be easily improved. and durability is further improved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An internal combustion engine filter and a filter regeneration device according to an embodiment of the present invention will be described below with reference to the drawings.

In the cross-sectional view of the system and main parts in FIG.
The exhaust gas introduction pipe 13 is a filter provided in the cavity 12 for collecting particulates, which has a honeycomb shape and closes adjacent through holes alternately on the windward and leeward sides, and is connected to the partition wall. When exhaust gas passes through, particulates accumulate on the partition walls. 14 is a spacer for insulating and buffering the filter 13. 15 is a magnetron which is a microwave oscillator as a heating source for particulates; 16 is a waveguide that transmits the microwaves oscillated by the magnetron 15 to the coaxial line 17; and 18 is the center conductor of the coaxial line 17, one end of which is a waveguide. It protrudes from the tube 16 and is coupled to the electric field. A dielectric 19 forms a coaxial line together with the inner conductor 18. In a coaxial line, the characteristic impedance of the transmission line is determined by the diameters of the center conductor and outer conductor, and the relative dielectric constant, relative magnetic permeability, etc. of the material interposed between them, and the material and dimensions of the relevant part are determined to ensure continuity of impedance. . The inner conductor 18 is arranged at the center of the exhaust introduction pipe 11 and projects into the cavity 12 using the exhaust introduction pipe 11 as an outer conductor, and a disc-shaped radiation antenna 20 is provided at the other end at a position facing the filter 14. ing. A portion of the exhaust introduction pipe 11 protrudes into the cavity, and a group of small holes 21 are provided on the outer periphery of this protrusion. Note that the exhaust introduction pipe 11 is arranged in the fluid passage direction of the filter 14 (X
-X' axis). 22 is a fluid supply means for supplying the cavity 12 with a fluid containing oxygen necessary for combustion of particulates during regeneration, and 23 is a fluid introduction pipe that communicates the fluid supply means 22 and the cavity 12.

While the engine is running, exhaust gas containing particulates flows through the exhaust inlet pipe 1 from the direction A in the figure.
1, part of it flows directly through the small hole group 21, and the other part hits the radiation antenna 20 and is deflected and flows into the filter 13 in the cavity 12, where particulates are removed by the partition wall of the filter 13 and released into the atmosphere. is released. The exhaust gas flow inside the cavity 12 becomes radial around the X-X' axis due to the small hole group 21 and the radiation antenna 20, and the particulate accumulation distribution becomes larger at the outer periphery than at the center. When the engine is operated for a certain period of time, the pressure loss of the filter 13 increases due to the accumulation of particulates, making it impossible to maintain good operation of the engine, so the pressure loss described above is detected and the filter 13 is regenerated. In the regeneration cycle, exhaust gas from the engine is stopped from being introduced into the exhaust introduction pipe 12 using a valve (not shown), etc., and the microwaves oscillated by the magnetron 15 energized by the drive power source are passed through the waveguide 16 and the coaxial line. 17 and is radiated into the cavity 13, heating the particulates near the opposing front surface of the filter to raise their temperature. When the particulates reach the ignition temperature, the fluid supply means 22 starts discharging combustion fluid containing oxygen. Combustion of particulates that starts near the front of the filter reacts with oxygen in the fluid and gradually spreads to the leeward side, and eventually the combustion ends and the filter 13 is regenerated. The supply of microwaves may be stopped immediately after it is detected that particulates are ignited. When regeneration is completed in this manner, exhaust gas is introduced into the filter again and particulate collection is resumed.

FIG. 2 is a sectional view of the system and main parts of a filter for an internal combustion engine in one embodiment of the present invention. Note that the same components as in FIG. 1 are given the same numbers. In FIG. 2, a resistance heating element 24 is connected to an electrical insulator 2 such as magnesium oxide at the tip of the protrusion of the exhaust introduction pipe 11 into the cavity 12.
A disk-shaped electric heater unit is provided which is fixed with an outer shell 26 via 5. Further, the center of the cross section of the filter 13 perpendicular to the fluid passage direction is filled with porous ceramic, which is the same material as the partition wall. While the engine is running, exhaust gas containing particulates flows into the exhaust introduction pipe 11 from the direction A in the figure, and part of it flows directly through the small hole group 21, while the other part hits the radiation antenna 20 and is deflected. The particulates flow into the filter 13 in the cavity 12, where the particulates are removed by the partition wall of the filter 13 and released into the atmosphere. The exhaust gas flow within the cavity 12 is radial about the X-X' axis due to the small hole group 21 and the electric heater unit, and the particulate deposition distribution is larger at the outer periphery than at the center. When the engine is operated for a certain period of time, the pressure loss of the filter 13 increases due to the accumulation of particulates, making it impossible to maintain good operation of the engine, so the pressure loss described above is detected and the filter 13 is regenerated. In the regeneration cycle, introduction of exhaust gas from the engine into the exhaust gas introduction pipe 12 is stopped using a valve (not shown) or the like, and energization of the electric heater unit is started. The electric heater unit that generates heat heats and raises the temperature of the particulates near the front surface of the opposing filter. When the particulates reach the ignition temperature, the fluid supply means 22 starts discharging combustion fluid containing oxygen. Combustion of particulates that starts near the front of the filter reacts with oxygen in the fluid and gradually spreads to the leeward side, and eventually the combustion ends and the filter 13 is regenerated. The power supply to the electric heater unit may be stopped immediately after it is detected that the particulates are ignited. When regeneration is completed in this manner, exhaust gas is introduced into the filter again and particulate collection is resumed.

FIG. 3 is a perspective view of an internal combustion engine filter according to an embodiment of the present invention. In FIG. 3, both filters have a substantially cylindrical shape and form a honeycomb structure made of porous ceramic. Exhaust gas is filtered by passing through the partition walls of the honeycomb structure, and particulates are deposited on the partition walls. In order to make the partition wall a filtration surface, a first sealing plug without pores is provided at each adjacent end of the through hole (in a checkerboard pattern), and the other end of the through hole without the first sealing plug is provided. A second sealing plug without pores is provided on one end surface side. In FIG. 3(a), the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is hollow. Also, Figure 3
In (b), the hollow at the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with the same porous ceramic as the honeycomb structure or the same porous ceramic as the sealing plug. Therefore, the particulates deposited on these two filters are independent of the collection cavity, and the amount of particulates collected in the center is small, making the heat distribution of the filter uniform during regeneration, and also improving the mechanical strength of the filter. .

[0025]

As described above, according to the internal combustion engine filter and filter regeneration device of the present invention, the following effects can be obtained. (1) A filter that collects particulates, a cavity that houses and holds the filter, an exhaust introduction pipe connected to the cavity that introduces exhaust gas into the cavity, and heats the particulates accumulated in the filter. and a heat source for combustion, the exhaust gas introduction pipe is provided at a position facing the filter, the terminal end of the exhaust gas introduction pipe is closed, the outer peripheral part is opened, and the exhaust gas flow is supplied radially to the cavity. Therefore, the exhaust gas flow is deflected by the exhaust inlet pipe and does not directly hit the front of the filter, preventing damage to the filter. Also, the distribution of particulates deposited on the filter is more concentrated on the outer periphery than in the center, so it is difficult to prevent damage to the filter during regeneration. The heat distribution of the filter is made uniform, improving regeneration efficiency and durability. (2) A microwave oscillator is used as the heat source for heating and burning the particulates, and the terminal end of the exhaust introduction pipe is blocked by a radiation antenna connected to the tip of a coaxial line with the microwave oscillator and the exhaust introduction pipe as the outer conductor. Because of this structure, the microwave transmission line can be constructed from existing members, and the microwave radiation antenna is provided at a position facing the filter, so that the microwaves can be effectively absorbed by the particulates in the filter. (3) The heat source for heating and burning the particulates is a resistance heating element, and the terminal end of the exhaust introduction pipe is closed with an outer shell provided on the resistance heating element via an insulator, so the resistance heating element Since the particulates are not directly exposed to exhaust gas, durability is increased, and a resistance heating element of any shape can be placed opposite the filter, particulates can be effectively heated and regeneration efficiency improved. (4) One end of the through hole of a honeycomb structure having a large number of through holes formed by porous ceramic partition walls is closed with a first sealing plug having no pores for each adjacent partition, and the other end is closed with a first sealing plug having no pores. Since the through-hole where the first sealing plug is not provided is closed with the second sealing plug without pores, and the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is hollow, the filter Thermal stress during playback is dispersed between the hollow part and the outer periphery, reducing thermal distortion, increasing thermal strength, and improving durability. (5) Since the hollow in the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with porous ceramic, it can be formed from the same material as the honeycomb structure, and this part also has a filter function. Therefore, the combustion air during regeneration is sufficiently diffused and the particulates are combusted, so that the regeneration rate is improved. In addition, since it also has a filter function, mechanical strength and durability are improved with a relatively small increase in pressure loss. (6) Since the hollow space at the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with porosity-free ceramic, filling can be done at the same time as the plug is applied, easily increasing the mechanical strength of the filter. durability is further improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of essential parts of an internal combustion engine filter regeneration device according to an embodiment of the present invention.

[Fig. 2] A cross-sectional view of essential parts of an internal combustion engine filter regeneration device according to an embodiment of the present invention.

FIG. 3 is a perspective view of an internal combustion engine filter according to another embodiment of the present invention.

[Fig. 4] Cross-sectional view showing the configuration of a conventional internal combustion engine filter regeneration device

[Explanation of symbols]

11 Exhaust introduction pipe 12 Cavity 13 Filter 15 Magnetron 16 Waveguide 17 Coaxial line 20 Radiation antenna 21 Small hole group

Claims (6)

[Claims] 1. A filter for collecting particulates contained in exhaust gas, which is provided in an exhaust passage of an internal combustion engine;
The exhaust gas introduction includes a cavity that houses and holds the filter, an exhaust introduction pipe connected to the cavity that introduces exhaust gas into the cavity, and a heat source that heats and burns particulates accumulated in the filter. A filter regeneration device for an internal combustion engine, wherein a pipe is provided at a position facing the filter, a terminal end of the exhaust introduction pipe is closed, an outer peripheral part is opened, and an exhaust gas flow is supplied radially to the cavity. 2. A microwave oscillator is used as a heat source for heating and burning the particulates, and a radiation antenna is connected to the end of the exhaust introduction pipe to the tip of a coaxial line having the microwave oscillator and the exhaust introduction pipe as outer conductors. The filter regeneration device for an internal combustion engine according to claim 1, wherein the filter regeneration device for an internal combustion engine is configured to be closed. 3. The heat source for heating and burning the particulates is a resistance heating element, and the terminal end of the exhaust introduction pipe is closed with an outer shell provided to the resistance heating element via an insulator. A filter regeneration device for an internal combustion engine as described in . 4. A honeycomb structure having a large number of through holes formed by porous ceramic partition walls, and closing one end of each of the through holes with a first sealing plug having no pores for each adjacent partition;
The other end closes the through hole where the first sealing plug is not provided with a second sealing plug without pores, and makes the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure hollow. A filter for internal combustion engines configured to 5. The filter for an internal combustion engine according to claim 4, wherein the hollow in the center of the cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with porous ceramic. 6. The filter for an internal combustion engine according to claim 4, wherein a hollow space at the center of a cross section perpendicular to the fluid passage direction of the honeycomb structure is filled with ceramic having no pores.