JPH04295121A - Filter for internal combustion engine and filter regeneration device - Google Patents

Abstract

PURPOSE:To provide high regeneration efficiency regardless of the quantity of particulates deposited inside a filter and high reliability with continuous capture and regeneration performance, in a filter for removing particulates including carbon in exhaust gas inside an internal combustion engine and a filter regeneration device. CONSTITUTION:An inclined joint part 20 is formed between the output antenna 18 of a magnetron 16 sated in the center line of a filter 14 in a fluid passage direction, and a cavity 13 which accommodates the filter. It is thus possible to make the impedance matching of an oscillator with that of the filter for highly efficient regeneration characteristics.

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. As exhaust gas regulations become stricter year by year, various studies are being carried out in an effort to maintain safety, and filters are available in foam types and monolithic types, depending on their configuration, and the heat source for regenerators is 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 the 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; is the exhaust gas flow switching valve. In such a configuration, spaces 9 and 10 are provided between the filter 7, which is disposed approximately at the center of the cavity resonator in the tube axis direction, and both end surfaces of the cavity resonators 2 and 3, respectively. There is.

Microwaves generated by the microwave generating means 6 pass through the waveguide 5 and are fed to the cavity resonator 2 or 3 from the radiation antenna 4 protruding into the spaces 9 and 10. The particulates collected on the porous ceramic partition walls of the filter 7 are dielectrically heated by the supplied microwaves, and when the temperature reaches about 600° C., they are ignited and burned, and the filter 7 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 stabilize TM01p. The mode could not be excited.

Furthermore, the front surface of the filter 7 is directly exposed to the exhaust gas stream when the engine 1 is running, so even though more particulates are deposited on the front surface of the filter 7, the microwave power applied during regeneration is not directly applied to the cavity resonators 2 and 3. Because there is a significant change in impedance at the boundary between the surface of the particulates and the surface where the particulates are deposited, microwaves are reflected and the temperature rise is small, and heat is radiated from the surface of the particulates by the black body, so the ignition temperature may not be reached or the temperature may not reach the ignition temperature for a long time. Even if microwaves are supplied to forcibly raise the temperature to the ignition temperature, the front surface of the filter will not function as a filter due to the non-ventilating blocking plugs installed alternately in adjacent cells, so combustion air must be supplied. However, there is a risk that the particulates will not be regenerated because there is no diffusion of oxygen to the particulates and no growth of combustion, and the pressure loss of the filter will increase in the unregenerated part at the front when collecting particulates after regeneration. Not only would this impede the proper operation of the engine, but there was a danger that the front section would become clogged and the filter function would be completely lost. 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 provides a highly reliable internal combustion engine filter that can burn particulates reliably in a short period of time regardless of the amount of particulates accumulated in the filter, has high heating efficiency, and can continuously maintain regeneration ability. The purpose of the present invention is to provide a filter regeneration device.

[0008]

[Means for Solving the Problems] In order to achieve the object, the filter regeneration device for an internal combustion engine of the present invention locates the output antenna of the microwave oscillator on the central axis in the fluid passage direction of the filter, and the output antenna A connecting portion between an insertion portion into the cavity and the filter holding front portion in the cavity is inclined.

Further, in the internal combustion engine filter of the present invention, one end of the through hole of a honeycomb structure having a large number of through holes formed by porous ceramic partition walls is sealed with a pore-free first seal for each adjacent partition. The other end of the through-hole is closed with a second sealing plug that has no pores and is located at least the diameter of the through-hole from the end surface of the through-hole where the first sealing plug is not provided. The partition wall and the sealing plug form a fluid passage.

Further, in the internal combustion engine filter of the present invention, the distance from the end face of the second sealing plug provided at a position remote from the end face increases from the center to the outer periphery of the filter.

Further, in the internal combustion engine filter of the present invention, one end of the through hole of a honeycomb structure having a large number of through holes formed by porous ceramic partition walls is sealed with a pore-free first seal for each adjacent partition. The other end of the through-hole is closed with a stopper, and the other end is closed with a second sealing plug having no pores, so that a fluid passage is formed between the partition wall and the sealing plug. At least one end of the honeycomb structure is not perpendicular to the fluid passage direction.

Further, in the internal combustion engine filter of the present invention, the sealing plug is provided at a position away from the end face of the through hole by at least the diameter of the through hole, and at least one end of the honeycomb structure It has a non-vertical configuration.

[0013]

[Operation] The filter regeneration device for an internal combustion engine of the present invention positions the output antenna of the microwave oscillator on the central axis of the filter in the fluid passage direction, and also connects the insertion portion of the output antenna into the cavity and the filter within the cavity. Since the connecting part with the holding front part is tilted, the microwave from the microwave oscillator is irradiated to the filter in the cavity via the tilted connecting part, which reduces the load (filter containing particulates). Even if the impedance of the microwave oscillator changes, matching between the impedance of the microwave oscillator and the load impedance is gradually performed at the connecting portion, so that microwave radiation can be performed efficiently.

Further, in the internal combustion engine filter of the present invention, one end of the through hole of a honeycomb structure having a large number of through holes formed by porous ceramic partition walls is sealed with a pore-free first seal for each adjacent partition. The other end of the through-hole is closed with a second sealing plug that has no pores and is located at least the diameter of the through-hole from the end surface of the through-hole where the first sealing plug is not provided. Since the structure is such that a fluid passage is formed by the partition wall and the sealing plug, one end of the fluid passage (the side where the second sealing plug is provided) has a filter function across the front, so it is used for combustion during regeneration. The regeneration rate is improved because the air is sufficiently diffused and burns to the front end.

Furthermore, since the internal combustion engine filter of the present invention is configured such that the distance from the end surface of the second sealing plug provided at a position remote from the end surface increases from the center of the filter to the outer periphery, More combustion air is diffused in the outer periphery, where the temperature is difficult to rise during regeneration, and the amount of particulates collected in this area increases, which not only further improves the regeneration rate, but also improves the heat distribution of the filter to prevent cracks caused by thermal strain. etc. can be avoided.

Further, in the internal combustion engine filter of the present invention, one end of the through hole of the honeycomb structure having a large number of through holes formed by porous ceramic partition walls is sealed with a pore-free first seal for each adjacent partition. The other end of the through-hole is closed with a stopper, and the other end is closed with a second sealing plug having no pores, so that a fluid passage is formed between the partition wall and the sealing plug. Since at least one end of the honeycomb structure is not perpendicular to the fluid passage direction, the effective surface area of the end face portion, which is difficult to regenerate, is expanded, which not only prevents clogging but also prevents the filter inside the cavity during microwave heating. Since the load impedance of the microwave gradually changes at the end face, microwave radiation can be performed efficiently and the regeneration rate can also be improved.

[0017]

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 sectional view of the system and main parts in FIG. 1, 11 is an engine, 12 is an exhaust introduction pipe for introducing engine exhaust gas into the cavity 13, and 14 is a pipe provided in the cavity 13 for collecting particulates. It is a honeycomb-shaped filter with adjacent through holes arranged alternately upwind and
It is closed on the leeward side, and particulates accumulate on the partition wall when exhaust gas passes through the partition wall. 15 is filter 1
This is a spacer for insulating and buffering 4. 16
17 is a drive power source that generates a high voltage to drive the magnetron 16; 18 is the magnetron 1;
6, and is located approximately on the central axis of the filter 14 in the fluid passage direction (X-X' axis). Reference numeral 19 denotes an antenna cover made of a heat-resistant, low dielectric loss material. 2
0 is a connecting portion that conveys the microwave output from the magnetron 16 to the cavity 13, and is inclined from the connecting portion of the output antenna 18 to the cavity 13. The dimension of the inclination of the connecting portion 20 may be determined while maintaining geometrical symmetry so that the impedance can be matched and the filter 14 can be heated uniformly. In addition, cavity 13
may be a square. While the engine 11 is operating, exhaust gas containing particulates is transferred to the exhaust introduction pipe 12.
The particulates flow into the filter 14 in the cavity 13, where the particulates are removed by the partition wall of the filter 14, and then released into the atmosphere through the external exhaust pipe 21. When the engine 11 is operated for a certain period of time, particulates accumulate in the filter 1.
Since the pressure loss of the filter 14 increases and it becomes impossible to maintain good operation of the engine 11, the aforementioned pressure loss is detected and the filter 14 is regenerated. In the regeneration cycle, the exhaust gas from the engine 11 is stopped from being introduced into the exhaust introduction pipe 12 by a valve (not shown), etc., and the microwaves oscillated by the magnetron 16 energized by the drive power source 17 are transmitted to the output antenna 18. Connecting portion 20 is transmitted to cavity 13.
The particulates near the front face of the opposing filter are heated and heated. When the particulates reach the ignition temperature, the air pump 22 begins to discharge combustion air. Combustion of particulates that starts near the front of the filter reacts with oxygen in the air and gradually spreads toward the leeward side, and eventually the combustion ends and the filter 14 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 plan view and a sectional view of a filter for an internal combustion engine according to an embodiment of the present invention. In FIG. 2, a honeycomb structure having through holes formed by porous ceramic partition walls 24 is formed in a cylindrical space surrounded by an outer frame 23. Reference numeral 25 indicates first sealing plugs without air holes provided at every adjacent end of the through-hole (in a checkerboard pattern), and reference numeral 26 indicates the other end of the through-hole without the first sealing plug. This is a second sealing plug provided on one end surface side. Second sealing plug 26
The distance from the end face becomes longer as the position where the mark is applied goes from the center of the honeycomb structure to the outer periphery in the exhaust gas inflow direction (A in the figure). Therefore, when exhaust gas flows into the filter and collects particulates, the amount of particulates collected increases from the center to the outer periphery of the honeycomb structure, and the temperature rise at the outer periphery due to combustion of particulates during regeneration increases. . Furthermore, since the entire front surface in the exhaust gas inflow direction is made of porous ceramic, it has a filter function, and combustion air is diffused during regeneration, so that the end surface can also be regenerated reliably.

FIGS. 3 and 4 are a front view and a side view of an internal combustion engine filter according to another embodiment of the present invention. Figure 3
, in FIG. 4, the filter 14 having a honeycomb structure has ends 27 and 28 facing the exhaust gas inflow direction (A in the figure).
is configured at one or more angles other than perpendicular to the fluid passageway. Therefore, the partial surface area that is directly hit by the exhaust gas becomes larger, making it less likely to become clogged. Further, when the filter 14 is housed in a cavity and heated by microwaves, the slopes of the ends 27 and 28 can gradually change the load impedance, so that there is little reflection of microwaves. Also,
The regeneration rate can be further improved by combining a filter with an inclined portion with a second sealing plug that is spaced apart from the end face.

[0021]

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 configuration in which the output antenna of the microwave oscillator is located on the central axis of the filter in the fluid passage direction, and the connecting part between the insertion part of the output antenna into the cavity and the filter holding front part in the cavity is inclined. Therefore, even if the load (filter containing different particulates collected in different amounts) changes, matching between the microwave oscillator impedance and the load impedance is gradually performed at the connection part. Can be heated and regenerated. (2) One end of the honeycomb structure having a large number of through holes formed by porous ceramic partition walls is closed with a sealing plug without pores at a position separated from the end face by at least the diameter of the through holes. Since the entire surface that is exposed to exhaust gas has a filter function, the combustion air during regeneration is sufficiently diffused and burns up to the front end, improving the regeneration rate.
Improved durability with no clogging. (3) Since the distance from the end face of the sealing plug applied at a position far from the end face is increased from the center of the filter to the outer periphery, more combustion is possible in the outer periphery where the temperature is difficult to rise during regeneration. As the air is diffused, the amount of particulates collected in the relevant part increases, so the temperature can be raised easily and the regeneration rate and durability are further improved. (4) Since one end of the honeycomb structure formed of porous ceramic is not perpendicular to the direction of the fluid passage, the effective surface area of the end face portion, which is difficult to reproduce, is expanded, and the durability is improved with less clogging.

[Brief explanation of drawings]

[Fig. 1] A system and a sectional view of essential parts of a filter regeneration device for an internal combustion engine in an embodiment of the present invention.

[Fig. 2] A plan view and a sectional view of an internal combustion engine filter according to an embodiment of the present invention.

[Fig. 3] Front view and side view of an internal combustion engine filter according to another embodiment of the present invention.

[Fig. 4] Front view and side view of an internal combustion engine filter according to another embodiment of the present invention.

[Fig. 5] A cross-sectional view showing the configuration of a conventional internal combustion engine filter regeneration device.

[Explanation of symbols] 11 Engine 13 Cavity 14 Filter 16 Magnetron 18 Output antenna 20 Connecting part 22 Air pump

Claims (5)

[Claims] 1. A filter for collecting particulates contained in exhaust gas, which is provided in an exhaust passage of an internal combustion engine;
It has a cavity that houses and holds the filter, and a microwave oscillator that dielectrically heats and burns particulates accumulated in the filter, and the output antenna of the microwave oscillator is positioned on the central axis of the filter in the fluid passage direction. The filter regeneration device for an internal combustion engine is configured to tilt a connecting portion between an insertion portion of the output antenna into the cavity and the filter holding front portion in the cavity. 2. 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 is closed with a second sealing plug having no pores at a position spaced apart from the end surface of the through-hole where the first sealing plug is not provided by at least the diameter of the through-hole, and the partition wall and the A filter for an internal combustion engine that has a structure in which a fluid passage is formed by a sealing plug. 3. The filter for an internal combustion engine according to claim 2, wherein the distance from the end surface of the second sealing plug provided at a position remote from the end surface increases from the center of the filter toward the outer periphery. . 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 end surface of the through hole where the first sealing plug is not provided with a second sealing plug without air holes to form a fluid passage by the partition wall and the sealing plug, and at least A filter for an internal combustion engine, wherein one end of the honeycomb structure is not perpendicular to the fluid passage direction. 5. The filter for an internal combustion engine according to claim 4, wherein the sealing plug is provided at a position separated from the end surface of the through hole by at least the diameter of the through hole.