JP2002070530A - Refreshing device of microwave filter for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely, surely refresh a filter for collecting particulates contained in exhaust gas of an internal combustion engine with a microwave electric power. SOLUTION: Plural metal link-shaped flat plates 11, 11, etc., are vertically arranged in the inner wall of a filter housing 4 in the length direction and in plural lines in the circumference direction, and the height h of the link-shaped flat plate 11 is made in almost λ/4 to the wave length λ of a supply microwave, installation intervals s in the length direction is set in λ/12-λ/4, the installation intervals w in the circumferential direction of the same plane of the link-shaped flat plate 11 is set in λ/2 or more, and a cylindrical outer cover 12 is installed in the outer surrounding of the cylindrical filter housing 4, in which plural link-shaped flat plates 11 are installed.

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 an internal combustion engine, particularly a filter for an internal combustion engine for collecting particulates contained in exhaust gas of a diesel engine, by heating the filter with microwave power. .

[0002]

2. Description of the Related Art The emission of particulates contained in the exhaust gas of internal combustion engines, especially diesel engines, is regulated for environmental protection and health reasons. Therefore, a ceramic honeycomb filter made of silicon carbide or the like is provided in the middle of the exhaust pipe so as to reduce the amount of particulates released into the atmosphere by collecting the particulates in the exhaust gas. Has been proposed.

According to this method, while the internal combustion engine is operating, particulates accumulate in the filter, and the pressure loss in the exhaust pipe increases to reduce the output of the diesel engine. The resulting particulates must be burned in a timely manner to carbon dioxide and water, which must be released into the atmosphere to regenerate the filter.

In the regeneration of this filter, the particulates cannot be burned only by the exhaust heat of the diesel engine. Therefore, as shown in JP-A-59-122022, the filter is collected by using a microwave heating means. The burned particulates were used to regenerate the filter.

In the above-mentioned Japanese Patent Application Laid-Open No. 59-122022, a columnar ceramic honeycomb filter containing silicon carbide as a main component is installed in a cylindrical filter container, and microwave power is supplied thereto. Irradiation causes the ceramic filter to generate heat and supplies combustion air to burn the particulates.

However, in the case of this method, the central portion of the columnar filter tends to become extremely hot compared with the outer peripheral portion, sometimes exceeding the heat resistance limit, and destroying the filter or the filter container. There was a problem. Generally, when a dielectric is rapidly heated by microwave power, the phase velocity in the dielectric is slowed, so that the microwave power tends to concentrate inside the dielectric, and the heat radiation on the outer peripheral side close to the outside air. This is because it is considered that this is because the temperature is relatively large, and the occurrence of a remarkable temperature difference between the inside and the outside is inevitably increased.

[0007] Some prior arts have been made to improve this problem, and are disclosed in Japanese Patent Application Laid-Open No. 06-323125.
In order to prevent a significant temperature difference between the inside and the outside of the filter, the invention disclosed in Japanese Patent Application Laid-Open Publication No. H11-15064 provides two microwave supply ports for supplying microwave power to the filter, and sets the installation interval of each to λ / 2 ( λ is the wavelength of the supplied microwave).

[0008]

However, according to the invention disclosed in Japanese Patent Application Laid-Open No. 06-323125, it is difficult to always effectively prevent the occurrence of uneven heating. In the first place, it is clear from the electromagnetic field analysis that the central part of the filter is inevitably hotter than the outer peripheral part, and it is necessary to take measures in consideration of the fact to solve the problem.

At this time, it is necessary to efficiently and uniformly heat the filter by the microwave power without impairing the operation of the internal combustion engine.

[0010]

According to the present invention, there is provided a columnar ceramic honeycomb filter for collecting particulates contained in exhaust gas of an internal combustion engine, and a columnar ceramic honeycomb. A metal cylindrical filter housing for housing the filter, an exhaust gas inlet pipe provided for introducing exhaust gas from the internal combustion engine into the filter housing, and an exhaust gas inlet pipe provided on the side opposite to the exhaust gas inlet pipe side An exhaust gas exhaust pipe for exhausting exhaust gas and the like from the filtered filter housing to the outside, a microwave oscillator for generating microwave power, and introducing microwave power from the microwave oscillator into the filter housing. A microwave supply port provided in the filter container,
A filter comprising a waveguide connecting the microwave supply port and the microwave oscillator, and a blower pipe provided for receiving combustion air on the microwave supply port side of the filter storage. A plurality of metallic link-shaped flat plates are vertically provided along the longitudinal direction and a plurality of rows are provided along the circumferential direction on the inner wall, and the height h of the link-shaped flat plate is substantially set with respect to the wavelength λ of the supplied microwave. λ / 4, the spacing s in the longitudinal direction is λ / 12 to λ / 4, the spacing w in the circumferential direction of the link-shaped flat plate in the same plane is λ / 2 or more,
A cylindrical outer cover is provided around the outer periphery of a cylindrical filter housing provided with a plurality of these link-shaped flat plates.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylindrical ceramic honeycomb filter for collecting particulates contained in exhaust gas of an internal combustion engine, and a metal cylindrical housing for accommodating the cylindrical ceramic honeycomb filter. A filter housing, an exhaust gas inlet pipe provided for introducing exhaust gas from the internal combustion engine into the filter housing, and an exhaust gas from a filter housing 4 provided on the side opposite to the exhaust gas inlet pipe. An exhaust gas exhaust pipe for exhausting gas, etc. to the outside, a microwave oscillator for generating microwave power, and a microwave provided in the filter housing for introducing microwave power from the microwave oscillator into the filter housing. The microwave supply port, the waveguide connecting the microwave supply port to the microwave oscillator, and the combustion at the microwave supply port side of the filter housing A plurality of metallic link-shaped flat plates are provided on the inner wall of the filter housing vertically along the longitudinal direction, and a plurality of rows along the circumferential direction. And the height h of this link-shaped plate is approximately λ
/ 4, the spacing s in the longitudinal direction is λ / 12 to λ / 4, and the spacing w in the circumferential direction of the link-shaped flat plate in the same plane is λ.
By setting at least / 2, uniform heating of the filter housing is performed.

Further, by providing a cylindrical outer cover around the outer periphery of the cylindrical filter housing provided with the link-shaped flat plate, even if leakage microwave power is generated from the filter housing, it is sealed in the outer cover. Thus, microwave power is prevented from leaking to the outside.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes an internal combustion engine. Reference numeral 2 denotes an exhaust gas intake pipe through which exhaust gas generated by operation of the internal combustion engine 1 passes. Reference numeral 3 denotes a columnar ceramic honeycomb filter containing silicon carbide as a main component. Reference numeral 4 denotes a metal-made cylindrical filter housing in which the cylindrical ceramic honeycomb filter 3 is housed, and the exhaust gas inlet pipe 2 is connected thereto. 5 is a microwave oscillator. Reference numeral 6 denotes a waveguide for guiding microwave power generated by the microwave oscillator 5 to the filter housing 4. Reference numeral 7 denotes a microwave supply port opened in the filter container 4 at the foremost part of the waveguide 6. Reference numeral 8 denotes a high-frequency power supply for driving the microwave oscillator 7. Reference numeral 9 denotes a blower tube provided on a side surface of the filter housing 4 for taking in outside air.

Reference numeral 10 denotes an exhaust gas exhaust pipe, which is the exhaust gas from the internal combustion engine 1 flowing into the filter housing 4, the air taken in from the blower pipe 9, and the carbon dioxide generated in the cylindrical ceramic honeycomb filter 3 by microwave heating. It is for discharging gas and the like. Further, the exhaust gas inlet pipe 2, the blower pipe 9, and the exhaust gas exhaust pipe 10 are all cylindrical pipes made of metal, and the diameter D of these pipes is determined by the cut-off wavelength of the microwave supplied by the microwave oscillator 5. Below, and the length of the tube is three or more wavelengths. Reference numeral 11 denotes a metal link-shaped flat plate, which is provided on the inner wall of the cylindrical portion of the filter container 4 at a plurality of pieces vertically and at equal intervals in the longitudinal direction thereof,
The inner peripheral surface supports the cylindrical ceramic honeycomb filter 3.

The link flat plate 11 is shown in FIGS.
As shown in FIG. 3, the height is set to approximately λ / 4 with respect to the wavelength λ of the supplied microwave, the installation interval s in the longitudinal direction is set to λ / 12 to λ / 6, A plurality of rows (four rows in FIG. 2) are arranged on the inner wall along the circumferential direction, and the circumferential installation interval w in the same plane is λ / 2 or more.

Reference numeral 12 denotes a metal cylindrical outer cover which is provided around the outer periphery of the cylindrical filter housing 4 provided with the link-shaped flat plate 11 and surrounds the filter housing 4.

Next, the operation of the present invention constructed as described above will be described.

When the internal combustion engine 1 is operated, its exhaust gas is led to the filter housing 4 through the exhaust gas inlet pipe 2. At this time, the particulates composed of carbon fine particles and the like contained in the exhaust gas are collected by the columnar ceramic honeycomb filter 3 provided in the filter housing 4 and formed of the ceramic honeycomb containing silicon carbide as a main component. . Then, the clean exhaust gas from which the particulates have been removed is discharged into the atmosphere through the exhaust gas exhaust pipe 10.

However, when the internal combustion engine 1 is operated for a long time, the particulates contained in the exhaust gas accumulate in the cylindrical ceramic honeycomb filter 3 to cause clogging.

Therefore, in order to regenerate the columnar ceramic honeycomb filter 3, the columnar ceramic filter 3 is heated by a method of periodically irradiating the columnar ceramic filter 3 in the filter housing 4 with microwave power. The accumulated particulates are converted to carbon dioxide and released to the atmosphere.

The method of converting the particulates of the cylindrical ceramic filter 3 into carbon dioxide and releasing it to the atmosphere is as follows.
First, the microwave power generated by the microwave oscillator 5 is guided from the microwave supply port 7 to the filter housing 4 through the waveguide 6. The microwave power guided to the filter housing 4 is applied to particulates mainly composed of carbon particles deposited on the cylindrical ceramic filter 3, and is converted into carbon dioxide when heated, and is taken in from the blower pipe 9. The carbon dioxide together with the extracted air is released from the exhaust gas exhaust pipe 10 to the atmosphere.

At this time, the exhaust gas inlet pipe 2, the exhaust gas exhaust pipe 10 and the blower pipe 9 connected to the filter housing 4 are constituted by cylindrical pipes, and the inner diameter D of each pipe is determined by a microwave oscillator. 5 and the length of the tube is sufficiently long with respect to the wavelength, so that the conventional exhaust gas inlet pipe 2 and exhaust gas exhaust pipe 10 are provided. It has the same microwave shielding function as the microwave shielding means using a metal punching plate.

Further, as shown in FIG. 2 and FIG. 3, the metal filter-shaped flat plate 11 is provided in the cylindrical filter housing 4 so that the center of the cross section of the cylindrical ceramic honeycomb filter 3 can be obtained. TM surrounds the surface layer portion of the side surface of the cylindrical ceramic honeycomb filter 3 in contact with the distal end portion of the distant link-shaped flat plate 11 and concentrates on the surface layer portion.
A filter that propagates in the axial direction of the cylindrical filter housing 4 made of metal in the form of a mode, and a cylindrical filter from the opening surface formed by the installation interval w of the link-shaped flat plate 11 and the height h of the link-shaped flat plate 11. Since microwave power is propagated to the center of the filter while propagating in the axial direction of the filter housing 4, the surface portion of the cylindrical ceramic honeycomb filter 3 and the center of the cylindrical ceramic honeycomb filter 3 are heated in a well-balanced manner. Thus, the cylindrical ceramic honeycomb filter 3 is uniformly heated.

Further, even if the leaked microwave power from the filter housing 4 is generated, it is sealed in the outer cover 12 and does not leak to the outside.

[0026]

As described above, according to the present invention,
A cylindrical ceramic honeycomb filter for collecting particulates contained in exhaust gas of an internal combustion engine, a metal cylindrical filter housing for housing the cylindrical ceramic honeycomb filter, and exhaust gas from the internal combustion engine Exhaust gas inlet pipe provided to introduce the exhaust gas into the filter housing, and an exhaust gas exhaust pipe for discharging exhaust gas and the like from the filter housing provided on the side opposite to the exhaust gas inlet pipe. A microwave oscillator for generating microwave power, a microwave supply port provided in the filter housing for introducing the microwave power from the microwave oscillator into the filter housing, A waveguide for connecting a wave oscillator and a microwave supply port side of a filter housing provided for receiving combustion air. In the case of a blower tube, a plurality of metallic link-shaped flat plates are provided on the inner wall of the filter container vertically along the longitudinal direction and in a plurality of rows along the circumferential direction. Is approximately λ / 4 with respect to the wavelength λ of the supplied microwave, and the longitudinal installation interval s is λ.
/ 12 to λ / 4, and by setting the circumferential spacing w of the link-shaped flat plate in the same plane to be λ / 2 or more, uniform heating of the cylindrical ceramic honeycomb filter can be performed, and the filter housing The generation of cracks due to melting and thermal shock of the aluminum alloy was suppressed. Therefore, the durability of the columnar ceramic honeycomb filter was enhanced, and a highly reliable filter regeneration device for an internal combustion engine was realized.

Further, by providing a cylindrical outer cover around the outer periphery of the cylindrical filter housing provided with the link-shaped flat plate, even if leakage microwave power from the filter housing occurs, it is sealed in the outer cover. Thus, by preventing the microwave power from leaking to the outside, there is an effect that a highly safe device can be provided.

Further, the outer cover has a heat insulating effect,
With a small amount of microwave energy, it also has the effect of raising the filter temperature within a short time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a system configuration according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a perspective sectional view showing a state where a cylindrical ceramic honeycomb filter is removed from FIG. 2;

[Explanation of symbols]

 1: Internal combustion engine 2: Exhaust gas intake pipe 3: Cylindrical ceramic honeycomb filter 4: Filter housing 5: Microwave oscillator 6: Waveguide 7: Microwave supply port 9: Blast pipe 10: Exhaust gas exhaust pipe 11: Linked flat plate 12: Outer cover

Claims (1)

[Claims] 1. A cylindrical ceramic honeycomb filter (3) for collecting particulates contained in exhaust gas of an internal combustion engine (1), and a metal housing the cylindrical ceramic honeycomb filter (3). A cylindrical filter housing (4), an exhaust gas inlet pipe (2) provided for introducing exhaust gas from the internal combustion engine (1) into the filter housing (4), and the exhaust gas inlet pipe ( 2) An exhaust gas exhaust pipe (10) for exhausting exhaust gas and the like from a filter housing (4) provided on the side opposite to the side, and a microwave oscillator (5) for generating microwave power. A microwave supply port (7) provided in the filter container (4) for introducing microwave power from the microwave oscillator (5) into the filter container (4); and a microwave supply port (7). )When A waveguide (6) for connecting a microwave oscillator (5) and a blower tube (9) provided on the side of the microwave supply port (7) of the filter housing (4) for receiving combustion air. A metallic link-shaped flat plate (1) is provided on the inner wall of the filter housing (4).
..) Are provided in a plurality in the vertical direction and in the circumferential direction in a plurality of rows, and the height h of the link-shaped flat plate (11) is set with respect to the wavelength λ of the supplied microwave. Λ / 4, and the longitudinal installation interval s is λ / 12 to λ /
4, the spacing w in the circumferential direction of the link-shaped flat plate (11) in the same plane is set to λ / 2 or more.
Cylindrical filter container (4) provided with a plurality of 1)
A microwave filter regeneration device for an internal combustion engine, wherein a cylindrical outer cover (12) is provided around the outside of the microwave filter.