JP2943320B2 - Regeneration device for filter for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine filter regenerating apparatus for removing carbon-containing fine particles (particulates) in exhaust gas of an internal combustion engine.

2. Description of the Related Art For a filter for collecting particulates in exhaust gas of an internal combustion engine (particularly a diesel engine) and a device for removing and regenerating the particulates accumulated in the filter, efforts have been made to prevent air pollution and preserve the environment. For this reason, various studies are being conducted as exhaust gas regulations become stricter year by year. As for the heat source of the regenerator, in addition to an oil burner and an electric heater, a microwave device has been proposed, but it has not been put to practical use.

Hereinafter, a conventional example (see JP-A-63-11416) will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes an engine, and a filter 3 for collecting particulates is fixedly supported in a filter housing 4 in a part of a passage in an exhaust pipe 2 of the engine 1. Reference numeral 5 denotes a magnetron for generating a microwave. The microwave is incident on the filter 3 from a microwave supply path 6 which is coupled to the filter housing 4 at high frequency and mechanically. At this time, the incident wave voltage and the reflected wave voltage of the microwave are detected by the antenna 7, and at the end of the reproduction, the operation time of the engine 1 and the incident wave, the reflected wave voltage and the like are input signals, and the magnetron 5
And a control device 8 for turning ON / OFF the output of the drive source.

By the way, when the particulates in the exhaust gas are accumulated in the filter 3 when the engine 1 is operated, the pressure loss of the filter 3 increases and the engine 1 cannot maintain a good operation state. When the collection amount is reached, the filter needs to be regenerated. According to the above-mentioned conventional technique, when the engine 1 reaches a certain operation time, the filter housing 4 irradiates a smaller microwave than the magnetron 5. The ratio between the incident wave voltage and the reflected wave voltage obtained at this time (which can also be expressed as a reflection coefficient) varies depending on the amount of accumulated particulate matter as a dielectric. Therefore, when the voltage standing wave ratio or the reflection coefficient reaches a predetermined value, the output of the irradiated microwave is increased to the extent that the particulates burn, and the filter 3
To play. During the regeneration of the filter 3, the incident wave voltage and the reflected wave voltage are continuously detected, and the burning of the particulates progresses, and when the particulates, which are the loads of microwave dielectric heating, decrease, the voltage standing wave ratio or the value of the reflection coefficient changes. To estimate the progress of filter regeneration. When this value returns before the particulate deposition again, the microwave supply is stopped.

SUMMARY OF THE INVENTION However, in such a conventional configuration, the state of accumulation of particulates is inferred only by the load impedance of the microwave, and the supply / stop of the microwave power is performed. The exhaust pressure of the filter 3 is high, and the exhaust gas flow in front of the filter 3 into which the exhaust gas flows changes variously depending on the operating conditions such as the number of revolutions of the engine 1 and the load condition. The load impedance will not be uniform and the change in load impedance will not be uniform, and erroneous detection will not occur (regardless of the accumulation amount, the reproduction will not start. As a result, unburned components remain, and as a result, the combustion temperature is partially increased, and the filter 3 is damaged due to a difference in temperature rise. There was a danger that the porous ceramic which is the material of the filter 3 would be melted and burned out.

In addition, the control of the air source which is indispensable for the combustion of particulates together with the heating source also has an important problem in constructing an optimum regenerating apparatus in combination with the means for detecting the regenerating time.

Accordingly, the present invention provides a highly reliable internal combustion engine filter regenerating apparatus capable of continuously maintaining the particulate regenerating ability by microwave with good heating efficiency for burning the particulates accumulated in the filter in a short time and reliably. It is intended to provide.

Means for Solving the Problems In order to achieve the above object, the present invention provides a filter for collecting particulates contained in exhaust gas provided in an exhaust passage of an internal combustion engine, a cavity for storing and holding the filter, and A microwave oscillator that dielectrically heats the particulates stored in the filter and an air supply unit that oxidizes and burns the dielectrically heated particulates, wherein the operation time period of the microwave oscillator and the operation time period of the air supply unit are The control is performed without overlapping.

Further, a regeneration cycle including the microwave oscillator and the air supply means is repeated a plurality of times during the regeneration.

In addition, the temperature measuring means includes an air supply means for oxidizing and burning the particulates, a second air supply means whose supply direction is opposed to the air supply means, and a temperature measurement means provided on an exhaust passage including a cavity. , The microwave oscillator, the air supply means, and the second air supply means are selectively operated.

Further, the apparatus has a temperature measuring means provided in the exhaust passage, and the temperature measuring means inhibits the operation of the microwave oscillator and the air supply means when the exhaust temperature is lower than a predetermined temperature.

The filter regeneration device for an internal combustion engine according to the present invention has a microwave oscillator for dielectrically heating the particulates deposited on the filter and an air supply means for oxidizing and burning the particulates heated by the dielectric, according to the above-described configuration. Since the operation time period of the wave oscillator and the operation time period of the air supply means are controlled so as not to overlap with each other, the particulate matter is heated by the microwave oscillator and quickly heated to a combustible temperature. Oxygen can be supplied by means to promote oxidation, thereby increasing the growth of the flame.

In addition, since the regeneration cycle composed of the microwave oscillator and the air supply means is repeated a plurality of times during the regeneration, the regeneration can be performed without the filter temperature becoming excessive due to the burning of the particulates.

In addition, there is provided air supply means for oxidizing and burning the particulates, second air supply means opposed to the air supply means and a temperature measurement means provided on an exhaust path including a cavity, and the temperature measurement means , The microwave oscillator, the air supply means, and the second air supply means are selectively operated, so that the temperature is increased by the microwaves and the combustion is promoted by the two air supply means /
By the suppression, the burning temperature of the particulates can be actively controlled.

Further, the apparatus has a temperature measuring means provided in the exhaust passage, and when the exhaust gas temperature is lower than a predetermined temperature, the operation of the microwave oscillator and the air supply means is prohibited. Regeneration can be performed at the time of collection and in a state where the temperature of each part of the filter is more uniform.

Embodiment Hereinafter, a regeneration apparatus for a filter for an internal combustion engine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a system and a main part of an apparatus for regenerating a filter for an internal combustion engine according to an embodiment of the present invention.
In the drawing, reference numeral 11 denotes an engine, and a cavity 14 is provided in a part of an exhaust passage of an exhaust pipe 12 of the engine 11, and a filter 13 for collecting particulates in the cavity 14 is thermally insulated from the cavity 14. And is held and held via a spacer 15 for buffering.

Further, the exhaust pipe 12 is provided with a control valve A16 for selecting an exhaust introduction pipe 17 for conveying the exhaust gas to the cavity 14 and a bypass pipe 18 for discharging the exhaust gas directly to the outside of the machine body. An air pump as an air supply means is provided below the cavity 14.
A control valve B20 for supplying the combustion control air from 19 into the cavity 14 in the forward / reverse direction with respect to the exhaust gas flow direction, and also serving as a second air supply means; It has a magnetron 21 for oscillating microwaves as a heat source, and transmits microwaves from the magnetron 21 into the cavity 14 via the waveguide 2.

Here, the drive power supply 22 is a converter or an inverter that converts a power supply 23 such as a battery or an alternator so that the magnetron 21 can be driven, and the sensors 25 and 26 detect the temperature or pressure of the exhaust introduction unit and the exhaust discharge unit, respectively. Things. The calculation unit 27 compares and calculates information such as fuel consumption, rotation speed, and output from the engine 11, information from the sensors 25 and 26, and a built-in timer (not shown). The operation of the drive power supply 22, the air pump 19, the control valve A16, the control valve B20, and the like is controlled by receiving a signal from the arithmetic unit 27.

Next, the operation of collecting / regenerating particulates will be described with reference to FIG. 2 which is an operation explanatory view of the internal combustion engine filter regenerating apparatus in one embodiment of the present invention.

In the figure, the horizontal axis shows the elapsed time of the collection / regeneration operation, the vertical axis A is a timing chart showing the operation of the magnetron 21, the air pump 19, the control valve A16 and the control valve B20, and the vertical axis B is The amount of the particulates deposited on the filter 13 is indicated by weight, and the vertical axis C indicates the temperature of the exhaust part of the cavity 14 measured by the sensor 26.

When the engine 11 is operated, the collection of particulates by the filter 13 is started. The control unit A16 changes the position so that the exhaust gas flows to the exhaust introduction pipe 17. Although the amount of accumulated particulates and the temperature of the exhaust section vary slightly depending on the operating conditions such as the number of revolutions and load of the engine 11, the engine 11
The operation unit infers the operation state information by analogy or filters 13
When the amount of accumulated particulates reaches a predetermined value due to the pressure difference between the sensors 25 and 26 provided before and after, regeneration is performed.

However, when the temperature of the exhaust gas is low because the engine 11 has just started, the temperature difference inside the filter 13 is large at the time of regeneration, so that the transition to the regeneration operation is prohibited.

When the exhaust gas temperature becomes equal to or higher than a predetermined value, the regeneration operation is started. The control valve A16 changes its position so that the exhaust gas flows to the bypass pipe. When the magnetron 21 starts to operate, the particulates in the filter 13 are dielectrically heated by the microwave, and the temperature rises while showing a slight weight loss.When the temperature reaches or exceeds the self-combustion temperature of the particulates, the magnetron 21 is stopped, and the air pump 19 is turned off. By operating, the control valve B20 supplies combustion air to the filter 13 from the microwave supply direction.

A flame is grown in the downstream direction while oxidizing and burning the particulates given air. However, if the combustion occurs too rapidly, the filter 13 may be damaged by heat or may be melted.Therefore, when the temperature of the exhaust section is measured and exceeds a predetermined temperature range, the control valve B20 changes its position, and the microwave supply direction is changed. Is supplied to the filter 13 from the opposite direction to suppress the propagation of combustion.

When the exhaust gas temperature falls below a predetermined value due to the suppressed combustion, the magnetron 21 starts operating again and the filter 13
The particulates inside are dielectrically heated by microwaves and heated up while showing a slight weight loss.When the temperature reaches or exceeds the self-combustion temperature of the particulates, the magnetron 21 is stopped again, the control valve B20 is switched, and the burning of the particulates is resumed. Be started.

When the particulate combustion approaches the end stage, the temperature rise of the exhaust unit per unit time decreases, so magnetron 21
Is stopped, and the reproduction operation ends. The control valve A16 changes its position so that the exhaust gas flows to the exhaust gas introducing pipe 17, and is again in the collecting operation state.

Although the air pump 19 and the control valve B20 are used as the air supply means and the second air supply means, two air pumps may be used, and the same effect can be obtained by using the exhaust gas of the engine 11. Can be

Effect of the Invention As is clear from the above description, the filter regeneration device for an internal combustion engine of the present invention has a configuration in which the operation time period of the microwave oscillator and the operation time period of the air supply means are controlled without overlapping. By heating the particulates by a microwave oscillator, the temperature can be quickly raised to a temperature at which combustion is possible, and oxygen is supplied by the air supply means to promote oxidation to promote the growth of a flame, so that waste energy is not consumed and the regeneration efficiency is good. .

In addition, since the regeneration cycle including the microwave oscillator and the air supply means is repeated a plurality of times during regeneration, the filter can be regenerated without excessive temperature of the filter due to burning of particulates, and the durability is good.

In addition, since the air supply means for oxidizing and burning the particulates and the second air supply means whose supply direction is opposite to the air supply means are selectively operated, the temperature is increased by microwaves, and the combustion by the two air supply means is performed. Promotion /
Due to the suppression, the burning temperature of the particulates can be actively controlled, so that the durability is further improved.

In addition, it has a temperature measuring means provided in the exhaust passage, and when the exhaust temperature is lower than a predetermined temperature, the operation of the microwave oscillator and the air supply means is prohibited. Regeneration can be performed at a more uniform temperature, and the durability is further improved without damage due to a temperature rise difference.

[Brief description of the drawings]

FIG. 1 is a main part cross-sectional system diagram of a main part of an internal combustion engine filter regenerating apparatus according to one embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of the internal combustion engine filter regenerating apparatus,
FIG. 3 is a main part sectional system diagram showing a main part of a conventional regeneration device for a filter for an internal combustion engine. 11 ... Engine (internal combustion engine), 13 ... Filter, 14 ...
Cavity, 19 Air pump (air supply means), 20
... Control valve B (air supply means), 21... Magnetron (microwave oscillator).

Continuation of the front page (56) References JP-A-58-65924 (JP, A) JP-A-59-126022 (JP, A) JP-A-61-11416 (JP, A) JP-A-3-210012 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F01N 3/02 301-341 F01N 9/00

Claims (4)

(57) [Claims] A filter provided in an exhaust passage of an internal combustion engine for collecting particulates contained in exhaust gas;
A cavity for accommodating and holding the filter, a microwave oscillator for dielectrically heating the particulates stored in the filter, and air supply means for oxidizing and burning the dielectrically heated particulates, the operation time of the microwave oscillator A filter regeneration device for an internal combustion engine configured to control a band and an operation time period of the air supply unit without overlapping. 2. The filter regeneration device for an internal combustion engine according to claim 1, wherein a regeneration cycle comprising a microwave oscillator and air supply means is repeated a plurality of times during regeneration. 3. A filter provided in an exhaust passage of an internal combustion engine for collecting particulates contained in exhaust gas,
A cavity for accommodating and holding the filter, a microwave oscillator for dielectrically heating the particulates stored in the filter, air supply means for oxidizing and burning the dielectrically heated particulates, and a supply direction relative to the air supply means. A second air supply unit to be provided, and a temperature measurement unit provided on an exhaust passage including a cavity, and the microwave measurement unit, the air supply unit, and the second air supply unit are selected by the temperature measurement unit. An apparatus for regenerating a filter for an internal combustion engine, which is configured to operate in an automatic manner. 4. A filter provided in an exhaust passage of an internal combustion engine for collecting particulates contained in exhaust gas,
A cavity for accommodating and holding the filter, a microwave oscillator for dielectrically heating the particulates accumulated in the filter, air supply means for oxidizing and burning the dielectrically heated particulates, and a temperature measurement provided in the exhaust passage A regenerating device for an internal combustion engine filter, comprising means for prohibiting the operation of the microwave oscillator and the air supply means when the exhaust gas temperature is below a predetermined temperature by the temperature measuring means.