JP2910430B2 - 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 that collects particulates (particulate matter) contained in exhaust gas discharged from a diesel engine.

[0002]

2. Description of the Related Art The high economic growth of so-called developed countries such as Europe, the United States and Japan has greatly contributed to civilization on the earth.
However, waste of fossil fuel energy, centered on economic growth in developed countries, has polluted the Earth's atmosphere.

[0003] With respect to global environmental conservation, measures against global warming, that is, measures for reducing CO2, have been highlighted recently, but measures against acid rain that causes deforestation cannot be ignored. Acid rain is a natural phenomenon that is caused by air pollutants such as sulfur oxides and nitrogen oxides as pollution sources. In recent years, regulations on the emission of such air pollutants have been imposed by fixed generation sources such as cogeneration and automobiles around the world. There is a movement that is strengthened against moving sources such as. In particular, regulations relating to automobile exhaust gas have been shifted from conventional concentration regulations to total quantity regulations, and the regulation values themselves are about to be significantly reduced.

[0004] Among automobiles, diesel vehicles are subject to stricter regulations on particulate emissions as well as nitrogen oxides. It is said that it is impossible to achieve the exhaust gas regulation value only by conventional measures for reducing pollutants in exhaust gas by improving combustion such as delaying fuel injection timing. At present, it is essential to provide an exhaust gas aftertreatment device. This post-processing device has a filter for collecting particulates.

However, if the particulates are continuously collected, the filter is clogged, the flow of exhaust gas is deteriorated, and the engine output is reduced or the engine is stopped.

[0006] Accordingly, technology development for regenerating the collection capacity of filters is currently being promoted worldwide.
Ensuring durability performance is a major practical issue.

[0007] It is known that particulates burn at about 600 ° C. As means for generating energy for raising particulates to this high temperature range,
A burner method, an electric heater method, a microwave method, and the like have been considered.

The present inventors have developed a microwave type filter regenerating apparatus in consideration of good temperature rising efficiency, safety, ease of apparatus configuration, and good regenerating control.

As a filter reproducing apparatus using a microwave system, there is, for example, JP-A-59-122022. FIG. 3 shows an apparatus disclosed in the publication. 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. Waveguide for guiding the generated microwave to the heating chamber, 9 a microwave reflector, 10 an air pump, 11
Is an air supply path, 12 is a driving power supply of the microwave generating means,
13 is a muffler, 14 is an air switching valve, and 15 is an exhaust gas flow switching valve.

In the above-described configuration, the exhaust gas of the engine is guided to the filter 5 by the exhaust gas flow switching valve 15 or directly discharged to the atmosphere. In the particulate collection cycle, the exhaust gas is guided to the filter 5 and the particulates contained in the exhaust gas are collected by the filter 5, but the collection capacity of the filter 5 is limited as described above. When the trapping capacity reaches the limit, the exhaust gas flow switching valve 15 is controlled, the exhaust gas to the exhaust pipe 3 is shut off, and all of 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 this filter regeneration cycle, energy for heating the particulates is supplied from the microwave generation means 7 and air required for combustion is supplied from the air pump 10 at the same time. When the regeneration of the filter is completed after a predetermined time, the exhaust gas flow switching valve 15 is controlled again, and the exhaust gas is led to the filter 5. This cycle of collection and regeneration is repeated.

[0011]

However, the above-mentioned conventional apparatus has the following problems when heating the particulates collected by the filter.

A fundamental problem is caused by the filter temperature when heating the particulates. Various problems arise from the filter temperature itself. For example, the forced gas flow flowing through the filter while heating the particulate to its combustible temperature, as shown by conventional devices, prevents efficient heating over time due to microwave heating. Requires a long heating time to reach the combustible temperature. Unless the filter temperature is managed, it is difficult to ascertain when particulates start to burn, and it is difficult to guarantee the durability of particulates for combustion removal.

Although the particulates are arranged so as to be collected almost evenly over the entire filter, the diameter of the filter is considerably larger than the diameter of the exhaust pipe. More particulates are collected. With respect to such a trapping distribution, the flow of the gas flowing through the filter flows more through a region avoiding the high pressure drop region (the center of the filter), and the flow distribution increases the pressure loss region (the center of the filter). In the filter, a heat distribution is suppressed and the temperature is high, while a low pressure drop region (the outer peripheral portion of the filter) forms a temperature distribution inside the filter such that the heat is promoted and the temperature is lowered. In such a situation, when microwave heating with an appropriate heating distribution is superimposed and particulate combustion starts, the combustion heat generated in a high collection area (the center of the filter) is suppressed because heat radiation is suppressed. High temperature combustion is promoted, and a high collection area (the center of the filter) and a low collection area (the outer periphery of the filter)
It becomes difficult to prevent the risk of causing mechanical damage to the filter during particulate combustion due to a large temperature difference between the filter and the filter. In such a state, when the temperature of the filter changes, the temperature distribution inside the filter changes more complicatedly, and it is virtually impossible to avoid mechanical damage to the filter.

As described above, the conventional technique cannot prevent mechanical damage and incomplete regeneration of the filter, and it is difficult to guarantee the durability of the filter.

The present invention has been made to solve the above-mentioned problems, and has a new function of effectively executing heating and burning of particulates, thereby guaranteeing high regeneration performance of a filter and ensuring durability of the filter. It is an object of the present invention to provide an engine filter regeneration device.

[0016]

In order to achieve the above object, the present invention provides an exhaust pipe for discharging exhaust gas from an internal combustion engine, and a particulate contained in the exhaust pipe and contained in the exhaust gas. A filter for collecting, a heating unit for heating the particulates, a combustion assisting unit for passing a combustion assisting gas for burning the heated particulates to the filter, and a passing gas after the filter for the combustion assisting gas flows A temperature detecting means for detecting a temperature, operating the auxiliary means before operating the heating means, supplying gas to the filter, and detecting a filter based on a signal from the temperature detecting means.
Control for determining the temperature of the filter is performed.

[0017]

[0018]

Here, the heating means includes a microwave generating means.

[0020]

[Action] In the foregoing construction, the auxiliary combustion means you cool filter very hot by the flow of the exhaust gas by supplying a natural air filter. To indirectly recognize the detected filter temperature by the temperature <br/> detector gas temperature of the post-filter through flow of the gas supplied by the combustion aid means
You. By this control, the temperature distribution inside the filter in the heating and burning removal process of the particulates executed by the heating means and the auxiliary means can be controlled to an optimum state, and the durability performance of the filter can be guaranteed.

[0021]

[0022]

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 16 denotes an exhaust pipe for exhausting an exhaust gas of an internal combustion engine (diesel engine) 17, reference numeral 18 denotes a heating space provided in the middle of the exhaust pipe 16, and reference numeral 19 denotes an exhaust gas housed in the heating space. filter comprising a honeycomb structure for collecting particulates contained in exhaust gas while passing through, 20 microwave generating means (Patikyure bets for generating microwaves fed to the heating space to dielectric heating particulates Heating means), 21
And 22 are linear and annular rectangular waveguides for transmitting the microwaves generated by the microwave generating means to the heating space 18; 23 are feed holes for feeding the microwaves to the heating space;
4 is constituted by combustion support means der Ri compressors and pumps for generating auxiliary燃気comprising oxygen flowing through the filter 19 in order to promote the burning of particulates which are dielectric heating.

Reference numeral 25 denotes a discharge pipe which is branched from the exhaust pipe 16 and through which an auxiliary gas flows, and one end of which is connected to the auxiliary means 24. Reference numeral 26 denotes a discharge pipe that is provided between the combustion support means 24 and the exhaust branch pipe 27 and through which a combustion supporting gas flows. Reference numeral 28 denotes an exhaust gas switching valve that allows exhaust gas discharged from the internal combustion engine 17 to flow through the filter 19 or
During the regeneration, the gas is passed through the exhaust branch pipe 27. 29
Is a muffler, and 30 is a temperature detection provided in the discharge pipe 25.
Ru means der.

Reference numeral 31 denotes a control section and a drive power supply section, which control operations of the microwave generation section 20 and the auxiliary combustion section 24 based on a detection signal of the temperature detection section 30.

The heating space 18 has microwave shielding means 32, 3 having a punching hole configuration or a honeycomb configuration.
3, the space for substantially confining the microwave is limited. Reference numeral 34 denotes a heat insulating material provided between the outer periphery of the filter 19 and the filter support tube 35, and also serves as a filter support.

An annular rectangular waveguide 22 is provided with a power supply hole 23 provided on the wall surface of an exhaust gas flow pipe 36 for guiding the exhaust gas flowing through the filter 19 to the rear exhaust pipe 16.
(One not shown) is located at the end. Further, the annular rectangular waveguide has an E-plane T-branch structure, and is configured such that transmission line lengths from the branch portion to each power supply hole are substantially equal. A structure 37 made of a microwave low-loss material that blocks the flow of exhaust gas is provided near the connection between the annular rectangular waveguide and the linear rectangular waveguide.

Exhaust gas discharged from the internal combustion engine 17 flows through the exhaust pipe 16 and flows into the filter. Filter 1
Reference numeral 9 denotes a wall flow type honeycomb structure having a function of collecting particulates contained in exhaust gas. When the amount of particulates collected by this filter increases, the pressure loss of the filter increases, the load on the engine as the internal combustion engine increases, and in the worst case, the engine stops.

Therefore, it is necessary to remove the particulates collected by the filter at an appropriate time. The means for determining the appropriate timing is based on the detection of the pressure drop level of the filter, the detection of the amount of trapped particulates by electrical means, or the integrated value of the operating state of the engine. The particulate matter trapped in the filter is removed by heating and burning. This process is called filter regeneration.

First, the operation of the portion relating to the present invention of the device having the above configuration will be described. The content of the operation differs before and after the operation of the microwave generation means 20. First, the contents before the operation of the microwave generation means 20 will be described below.

This operation is an operation for defining the temperature of the filter in a predetermined temperature zone. When the internal combustion engine is operating, exhaust gas is guided to the exhaust branch pipe 27. First, the auxiliary means 24 is operated. This allows the exhaust pipe end 38
Air is entrapped. This air flows through the filter 19 and is discharged to the atmosphere via the discharge pipe 25, the auxiliary means 24, the discharge pipe 26, the exhaust branch pipe 27 and the muffler 29.
The flow of the air flows through the filter 19, which has been heated by the exhaust gas, to remove heat from the filter and become hot. The ventilation temperature after the passage of the filter is detected by the temperature detecting means 30. The temperature of the filter is indirectly detected based on the detection signal. This flow is passed through the filter 19
Until the temperature reaches a predetermined temperature zone. By controlling the filter temperature to a specified temperature range, the particulate combustion state during filter regeneration can be controlled to a substantially constant state, and the durability performance of the filter is guaranteed.

When the temperature of the filter reaches the specified temperature range, the operation of the auxiliary combustion means 24 is stopped, and at the same time, the operation of the microwave generation means 20 is started. The contents after the operation of the microwave generating means 20 has been started will be described in the description of the basic process of filter regeneration described later.

Next, FIG. 2 will be described. FIG. 1 of FIG.
The difference in configuration is that the auxiliary means 39 is constituted by a blower. Auxiliary means 39 composed of a blower
Is provided on the exhaust gas discharge side of the filter 19. In this case, the exhaust pipe 1
6, a blower pipe 41 and a discharge pipe 42 for shielding 6
Valve 4 for preventing exhaust gas from leaking and forming a ventilation path for an air flow generated by the blower
3, 44 are provided. The configuration around the microwave generation means (heating means) 20 is the same as that in FIG.

The discharge pipe 42 is provided with a temperature detecting means 30. The air blown through the filter 19 by the blower 39 deprives the filter of heat and becomes high in temperature, so that the exhaust pipe 42
To flow. The temperature of the high-temperature flow is detected by the temperature detecting means 30 and the blower 39 is operated until the temperature falls to a predetermined temperature zone. When the temperature detected by the temperature detecting means reaches the specified temperature range, the operation of the blower is stopped and at the same time, the microwave generating means 2
0 starts operation and dielectrically heats the particulates collected in the filter. The control unit 45 executes these series of controls. It should be noted that a compressor or a pump can be used as the auxiliary combustion means even in the arrangement of the auxiliary combustion means 39 as shown in FIG.

As described above, the heating temperature distribution during the particulate heating and the combustion temperature distribution during the combustion are controlled to desired distributions by controlling the filter temperature before executing the heating of the particulates to a predetermined temperature zone. it can be, it has become possible to guarantee the durability of the filter to prevent mechanical damage to the well filter maintenance of playback performance.

Finally, the details of the basic process of filter regeneration will be described. When the amount of particulates collected by the filter reaches the collection amount area where filter regeneration should be performed,
Initiate the filter regeneration process.

The reproduction control command is issued from a control unit incorporated in the apparatus or a control unit responsible for controlling the entire system in which the apparatus is incorporated. The exhaust gas switching valve 28 is controlled based on a command from the control unit. When the internal combustion engine is operating, the exhaust gas flowing into the filter is shut off and the exhaust gas is led to the exhaust branch pipe 27. After this state, the auxiliary means starts operating in order to set the temperature of the filter 19 to a specified temperature zone. First, the auxiliary combustion means 24 and 39 operate to create a flow of gas other than the exhaust gas flowing through the filter 19. This gas flow cools the filter 19 which has been heated by the exhaust gas.
The gas flow temperature after flowing through the filter to control the filter temperature to a specified temperature band is detected by the temperature detecting means 30. The auxiliary means continues to operate until the detected temperature reaches the specified temperature zone. When the temperature reaches the specified temperature range, the operation of the auxiliary combustion unit is stopped, and the driving power is supplied to the microwave generation unit 20. The microwave generated by the microwave generating means is fed to the filter housing heating space via the waveguide means. The particulates collected in the filter are selectively dielectrically heated by the microwaves, and the heated area extends to the inside of the filter. As time elapses, the temperature reaches the combustible temperature sequentially from the particulate present near the filter end face on the microwave incident side, but the microwave power supply is continued. When the temperature reaches the combustible temperature, the particulates in that region glow red and partially burn, but the expansion of combustion is suppressed by the lack of oxygen, and the temperature rise is saturated. With the continuation of the microwave power supply, the region reaching the combustible temperature of the particulates is expanded to １ ／ to の of the filter. At this time, the flow of the exhaust gas and other gases in the filter is almost completely shut off, so that the microwave-heated particulates efficiently rise in temperature toward the combustible temperature range.

After microwave heating is performed for a predetermined time or for a time determined based on the amount of trapped particulates of the filter 19, the auxiliary combustion means is again operated and the particulates are fed from the end face of the microwave-powered filter. Supplementary combustion gas that promotes combustion is supplied. The particulates heated to a high temperature in the filter by this gas shift to a combustion state. The combustion area expands while moving in the direction of flow of the auxiliary combustion gas. In parallel with the movement of the combustion area, the temperature of the auxiliary combustion gas after flowing through the filter is detected by the temperature detecting means. The microwave generation means continues to operate until the detected temperature reaches the predetermined temperature or for a predetermined time after the restart of the operation of the auxiliary combustion means. Even after the operation of the microwave generating means is stopped, the temperature detected by the temperature detecting means rises. After this temperature reaches the maximum value, the auxiliary combustion means is operated for a predetermined time. By this operation, the temperature of the filter 19 returns to the temperature level at the time when the operation of the microwave generation means starts. This completes the filter regeneration.

When the filter regeneration cycle is completed, each valve is controlled to the state before the regeneration cycle, and at the same time, the exhaust gas flows into the filter 19 to collect particulates.

The structure of the means for transmitting microwaves to the heating space is not limited to the embodiment of the present invention.
For example, a coaxial transmission line can be used.

[0042]

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

[0043]

( 1 ) Auxiliary means before operating the heating means
The is operated can indirectly grasp the filter temperature before the heating means operate by detecting the gas stream temperature after the filtering through flow
You. This allows regeneration to prevent mechanical damage to the filter
Control and ensure the durability of the filter.
I can .

( 2 ) The temperature of the flowing gas after flowing through the filter is detected.
By utilizing the temperature detecting means, the progress of the combustion state during the regeneration as well as the temperature before the regeneration of the filter can be grasped, and effective regeneration control can be executed.

[0046]

( 3 ) By constituting the particulate heating means with microwave generating means, the flow of gas flowing through the filter during the particulate heating can be almost completely shut off, and the temperature distribution inside the filter during heating can be reduced. Can be unified into a microwave heating distribution. Thereby, the reproducibility of the filter regeneration performance can be guaranteed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a filter regeneration device for an internal combustion engine showing one embodiment of the present invention.

FIG. 2 is a configuration diagram of a filter regeneration device for an internal combustion engine showing another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional filter regeneration device for an internal combustion engine.

[Explanation of symbols]

16 an exhaust pipe 17 internal combustion engine 19 filter 20 microwave generating hand stage (heating means) 24 and 39 combustion support means 25,26,42 discharge pipe 30 temperature detecting means 31 and 45 control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI F01N 9/00 F01N 9/00 Z (56) References JP-A-6-2530 (JP, A) JP-A-63-71511 ( JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01N 3/02 301-341 F01N 9/00

Claims (2)

(57) [Claims] An exhaust pipe for exhausting exhaust gas of an internal combustion engine,
A filter that is contained in the exhaust pipe and collects the particulates contained in the exhaust gas, a heating unit that heats the particulates, and an auxiliary gas that burns the heated particulates flows through the filter. A combustion assisting means, and a temperature detecting means for detecting a flowing gas temperature of the assisting gas after passing through the filter, and operating the assisting means before operating the heating means to supply a gas to the filter, thereby controlling a temperature. A filter regeneration device for an internal combustion engine, which performs control to determine the temperature of a filter based on a signal from a detection means. 2. The filter regeneration device for an internal combustion engine according to claim 1, wherein the heating means includes a microwave generation means.