JP3078942B2 - Exhaust gas treatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment device having a filter disposed in a casing incorporated in an exhaust passage for purifying exhaust gas discharged from an engine.

[0002]

2. Description of the Related Art Diesel engine combustion is based on so-called heterogeneous mixing in which fuel is injected into high-temperature, high-pressure air. Heterogeneous mixing differs from a homogeneous mixture in that air and fuel are not uniformly mixed, so the carbon component in the fuel changes to soot, HC, etc. due to the high-temperature heat of combustion, and they aggregate to form particulates. Released into the air. Smoke is suspended in the atmosphere as fine particles of carbon and particulates having hydrocarbons attached to the periphery thereof, so that pollution of the urban environment progresses and the transparency of the air extremely deteriorates.

Conventionally, as an exhaust gas processing apparatus for processing exhaust gas of an engine, for example, cordierite (2M
There is disclosed a device for purifying exhaust particulates of a diesel engine in which two sets of filters having a porous honeycomb structure made of gO.2Al ₂ O ₃ .5SiO ₂ ) are arranged in parallel in an exhaust passage. The exhaust gas purifying apparatus of the diesel engine passes the exhaust gas through one of the filters having a honeycomb structure, captures carbon in the exhaust gas with the filter, and removes carbon when the filter is clogged with carbon. Cut off the exhaust gas flow to the filter, switch the exhaust gas flow to another filter, send air from the downstream side of the clogged filter, heat the filter and incinerate the clogged carbon Things. An example of such a device for purifying exhaust particles of a diesel engine is disclosed in Japanese Utility Model Laid-Open No. 1-144427.

[0004] Japanese Utility Model Laid-Open Publication No. 1-136617 discloses a particulate filter. In the particulate filter, thin-walled porous elements also serving as heaters made of conductive ceramics are arranged in a plurality of stages, and power can be individually supplied to each of the porous elements and each of the powers can be controlled.

Japanese Utility Model Laid-Open Publication No. 3-116722 discloses an exhaust gas purifying apparatus for a diesel engine. The exhaust gas purifying apparatus for a diesel engine includes a columnar ceramic filter in which a number of cells extending in a longitudinal direction are formed, and an electric heating member provided on an outer periphery of the filter. , Filled with a powder having good thermal conductivity.

[0006]

Incidentally, diesel particulate is a composite of carbon and hydrocarbon contained in a diesel engine, and its size is several μm.
To several tens of μm. The particulates easily react with oxygen and burn, but the combustion requires a high temperature, and cannot be completely burned only by the exhaust gas temperature. Therefore, many devices for removing particulates and smoke have been developed in the past, but they all have drawbacks and cannot be put to practical use at present.
In a diesel particulate filter (DPF) that collects and incinerates particulates such as carbon, soot, and HC contained in exhaust gas exhausted from a diesel engine by a filter, that is, in an exhaust gas treatment device, carbon, soot,
Particulates such as HC are collected by a filter, that is, a filter, and when the particulates accumulate on the filter, they are heated by an ignition glow plug or a heater to incinerate particulates such as soot.

[0007] Further, the conventional automobile has a shortage of electric energy and cannot obtain a sufficient power generation amount.
It is sufficient to use a large-capacity generator for power generation, but with a conventional DC or AC generator, the generator capacity becomes too large.
Mounting on the engine becomes difficult due to space. In an AC machine using a permanent magnet as a rotating body, a brush is not required for the rotor, and the resistance to the rotating body is small, so that the rotating body can be rotated at high speed. Therefore, if a generator with a structure that rotates a generator consisting of permanent magnets with high magnetic force at high speed can be produced, a large amount of power can be obtained, and electric power is constantly supplied to the diesel particulate filter as described above. can do. For example, a large power generation amount can be obtained by providing a turbocharger operated by exhaust gas energy of an engine with a generator made of a permanent magnet having a high magnetic force.

However, in such a method for burning particulates, the temperature rises excessively due to combustion of soot or the like, and for example, a ceramic filter such as cordierite is broken, cracked, burned out, etc., and the filter is damaged. This is a problem that is not practically preferable.
In particular, even if the filter is made of heat-resistant ceramics, in the case of non-uniform combustion of particulates such as soot deposited on the filter, many high-temperature portions exist locally in the filter,
In many cases, cracks and the like occur in ceramics constituting the filter.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems. An upstream filter made of ceramics having coarse pores is disposed upstream in an exhaust passage for purifying exhaust gas, and pores are disposed downstream. A downstream filter made of fine ceramics is arranged, a heater is provided in the upstream filter to heat it, the gas temperature rises, and a groove is formed in the upstream and downstream of the downstream filter to increase the contact area. The particulate matter containing large particles such as soot contained in the exhaust gas is collected by the upstream filter and incinerated, and the particulate matter small particle on the downstream side is collected by the filter with a large contact area on the downstream side and incinerated. Prevents the presence of particulates in the filter from locally accumulating, and also prevents clogging, so that particulates are always kept in the filter. Incineration to purify exhaust gas gasified, also is to provide an exhaust gas treatment apparatus using the power recovered power to energize the heater in the exhaust gas energy of the engine.

[0010]

SUMMARY OF THE INVENTION The present invention provides a casing incorporated in an exhaust passage through which exhaust gas from an engine flows, and a casing having coarse pores disposed in the casing on the upstream side of the flow of the exhaust gas. An upstream filter, a downstream filter having fine pores disposed downstream of the upstream filter, and the stacked upstream filters are separated in a non-contact state in a direction intersecting the flow of the exhaust gas. And a power supply means for supplying power to the heater, wherein the upstream filter and the downstream filter are formed of non-conductive porous ceramics, and The downstream filter is made of a flat ceramic, and the downstream filter is provided with a large number of upstream and downstream sides of the flat ceramic to increase the contact area with the exhaust gas. There is formed, the heater is an exhaust gas treatment apparatus consists of extending connected electrically in series to each other are sequentially bent from the upstream side to the downstream side in the upstream side filter in the upstream filter.

[0011] Further, a pair of processing chambers formed by dividing the inside of the casing into two by a partition plate and in which the heater, the upstream filter and the downstream filter are respectively arranged, and an inlet of each of the processing chambers. And a switching valve having a leak hole through which a small amount of exhaust gas can flow to the processing chamber on the closed side.

The switching valve is switched at a predetermined period set in advance by a timer.

The exhaust gas processing apparatus further includes sensors for detecting the exhaust gas pressure at the inlet of each of the processing chambers, and controls the switching time of the switching valve in response to a detection signal from each of the sensors, and controls the switching time of the switching valves. It has a controller for controlling the supply of electric power to the heater.

Further, the power supply means is constituted by a generator provided in a turbocharger driven by exhaust gas energy of an engine disposed upstream of the casing provided with the upstream filter and the downstream filter. Is what it is.

Further, in this exhaust gas treatment device, a heat insulating material is disposed between the casing and the filter.

Since this exhaust gas treatment apparatus is configured as described above, particulates such as smoke having large particles such as soot on the upstream side of the filter cause the passage to change zigzag in the middle of the flow. The particles can be incinerated, and the particles can be incinerated. Particulates of fine particles are collected by a downstream filter having an increased contact area due to the formation of a groove, and are incinerated by the heat of the gas heated to a high temperature upstream.

In addition, the temperature of the downstream filter rises considerably. However, since the filter itself is constructed in a divided manner, if it is made of a ceramic having high heat resistance such as silicon nitride or silicon carbide, it will have a high temperature strength. Can be improved, and
By forming the groove in the downstream filter, it is easy to manufacture even ceramics such as silicon carbide. Therefore,
The filter can be constantly heated by the heater, and the particulates such as carbon, soot, and HC trapped by the filter are immediately incinerated into gas, and the particulates are not excessively deposited in the filter. In particular, clogging of the filter on the upstream side can be prevented, the filter does not have a local high-temperature portion, and the filter does not break due to cracks, cracks, burnout and the like.

In this exhaust gas treatment apparatus, a casing disposed in an exhaust system is divided into two parts by a partition plate to form a pair of processing chambers, and an inlet passage of the processing chamber is formed by a switching valve having a leak hole. Open / close operation, a small amount of exhaust gas flows into the inlet passage on the closed side through a leak hole provided in the switching valve, and a dual type in which a heater, a conductive connection member, and a filter are disposed in each processing chamber. Therefore, by switching the switching valve, one of the processing chambers opens the switching valve to allow a large amount of exhaust gas to flow, while the other processing chamber has a small amount of exhaust gas flowing through the leak hole. The filter, which is in a state where a small amount of exhaust gas flows, is quickly heated to a high temperature by the heater, and the collected particulates such as carbon, soot, and HC are reduced. It is incinerated in fast. While the particulates are incinerated, the switching valve is switched to incinerate the particulates collected by the filter in the other processing chamber. By repeating the switching operation of the switching valve, the filter can always be efficiently purified.

However, in order to incinerate the particulates trapped in the filter, the temperature of the exhaust gas must be maintained at a high temperature, and the flow rate of the exhaust gas passing through the filter is reduced so that the cooling effect is not generated. In addition, it is effective to increase the heating heat energy in multiple stages to reach the particulate combustion temperature.
For example, when the inside of the casing is not divided into two parts, and when the entire amount of exhaust gas is passed through the filter, the amount of passing exhaust gas becomes too large, heat energy is taken by the exhaust gas, and the temperature of the filter decreases. A phenomenon occurs that the particulates cannot be ascended and the particulates cannot be incinerated.

Further, since a generator for generating electricity by operating a turbocharger driven by the exhaust gas energy of the engine is used as the electric power supply means, a large amount of electric power is required to supply electricity to the heater. The electric power supplied to the heater is electric power generated by exhaust gas energy using a generator provided in a turbocharger, and the electric power is not insufficient and the collecting function and the incineration function of the filter are not reduced. . Therefore, the heater can always be supplied with electric power, the filter can be constantly heated, particulates such as carbon trapped in the filter can be incinerated immediately, and excess carbon is deposited on the filter. Thus, the filter is not clogged.

In the exhaust gas treatment apparatus, a controller detects a detection signal of a sensor for detecting an exhaust gas pressure in each of the processing chambers and a sensor for detecting an operation state of the engine, which is arranged on an inlet side of each of the processing chambers. In response to the control of the switching time of the switching valve and the supply of electric power to each of the heaters, the switching time of the switching valve can be given a degree of freedom. The switching valve can be switched in accordance with the particulate collection state, and the filter can always be maintained in an optimal state in which the particulates can be collected, thereby improving the particulate collection efficiency of each filter. be able to.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exhaust gas treatment apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing one embodiment of an exhaust gas treatment apparatus according to the present invention. The exhaust gas processing apparatus 1 includes an upstream filter having a coarse pore structure made of a non-conductive porous ceramic capable of purifying an exhaust gas in a casing 20 stacked and disposed in an exhaust system such as an exhaust passage 2. 4R and a downstream filter 4F (general name of the filter is indicated by reference numeral 4) having a fine pore structure. In the casing 20, the heaters 22 are arranged in a non-contact state with each other in a direction intersecting the flow of the exhaust gas, and are sequentially separated from each other in the flow direction. In the upstream filter 4R, the heater 22 is disposed so as to sandwich the upstream filter 4R, and the heater 22 is disposed so as to be embedded in the upstream filter 4R. The heater 22 is electrically connected in series from the upstream side to the downstream side in the exhaust gas flow direction by the conductive connection member 15. Each connection member 15
May be the heater 22 itself. In this case, the heater 22 is composed of one heater from the upstream side to the downstream side in the flow direction of the exhaust gas, and is bent sequentially from the upstream side to the downstream side as shown in the figure. It will be formed in the state where it was done.
A heat insulating material 19 is disposed between the casing 20 and the filter 4 in order to prevent the heat energy of the exhaust gas from radiating to the outside.

Further, in order to burn the particulates collected by the filter 4, there is provided an electric power supply means for supplying electric power to the heater 22. The power supply means varies depending on the exhaust system in which the exhaust gas treatment device 1 is used. When the exhaust gas treatment device 1 is applied to stationary equipment, a normal power supply is used, or FIG. A turbocharger 5 having a generator 6 as shown can be used. The turbocharger 5 has a turbine 7 driven by exhaust gas energy at one end and a compressor 8 at the other end of a shaft 11 having one end fixed to the turbine 7 and a permanent magnet having a high magnetic force fixed to the shaft 11. A rotor is formed using magnets 9, and an electromagnetic coil as a stator is arranged on the outer periphery of the rotor to constitute a generator 6. Since the generator 6 does not have a brush or the like and the rotor and the stator are in a non-contact state, the generator 6 can rotate at a high speed with a small friction loss, so that a large power generation amount can be obtained. In this case, the turbocharger 5 does not necessarily need to be provided with the compressor 8 and can be configured as a power generation turbine including only the generator 6.

In particular, the filter 4 is made of non-conductive porous ceramics, the upstream side of the exhaust gas is constituted by an upstream filter 4R having a coarse pore structure, and the downstream side is formed by a downstream filter 4F having a fine pore structure. The downstream filter 4F is formed with grooves 28 upstream and downstream so as to increase the contact area with the exhaust gas. That is, the upstream filter 4R can be configured by laminating plate-shaped ceramics in the flow direction. The downstream filter 4F
By closing every other upstream and downstream end of the flat ceramics, grooves 28 can be easily formed even with ceramics such as silicon carbide and the surface area can be increased. Of course, the groove 28 may be a spiral groove, a large number of continuous or separated circular grooves, or a large number of continuous or separated linear grooves, and is preferably shaped so as to increase the contact area with the exhaust gas. . Further, the filter 4 is
And the heater 22 may be arranged between the blocks, and the heater 22 may be interposed or embedded in the upstream filter 4R.

In particular, the upstream filter 4R is made of aluminum oxide Al ₂ O ₃ , cordierite 2MgO.2Al
_{It is made} of non-conductive porous ceramics such as ₂ O ₃ · 5 SiO ₂ , titania TiO _{2 and the} like, and the downstream filter 4F is made of silicon nitride Si ₃ N ₄ , silicon carbide SiC and other high heat resistant high strength. And a porous sintered material having a porosity of substantially 40% to 50% or more can be used. The filter 4 can exhibit sufficient high-temperature strength to incinerate particulates such as carbon, soot, and HC. For example, the filter 4 sufficiently collects undesirable particulates such as carbon contained in exhaust gas of a diesel engine. Can be. Further, as for the filter 4, it is preferable that the porous gap is large without causing clogging.
After impregnating the polyurethane foam with a ceramic slurry or slurry using a polyurethane foam, drying and solidifying the resultant, the resultant is fired to burn out the polyurethane foam to produce a porous ceramic or porous body having a desired size. it can. Alternatively, a slurry is prepared by mixing ceramic raw material powders, and resin particles are added to the slurry, mixed and dried and solidified, and then fired to burn off the resin particles, thereby forming a porous ceramic of a desired size. A porous body can be produced.

The heaters 22 are arranged in the casing 20 so as to be separated from each other in the longitudinal direction in the flow direction of the exhaust gas so as not to be electrically short-circuited in a non-contact state. It is efficient to supply a current to the heater 22 from the upstream side to the downstream side of the exhaust gas flow to heat the heater 22 at each stage and raise the temperature at each stage of the porous ceramics upstream filter 4R. It is a target. The heater 22 and the connecting member 15 are made of a Ni—Cr heat-resistant metal such as Incoloy. When the heater 22 is made of a heat-resistant Ni-Cr metal, the heater 22 can sufficiently function as a heater by supplying electricity to the heater 22, and the filter 4 can be sufficiently maintained at a high temperature. I can put it. Further, the ends of the heater 22 are electrically connected to each other at the adjacent ends by the conductive connecting member 15, and therefore, the heaters 22 are electrically connected in series. That is, the heater 2 located upstream and downstream
2 are electrically connected to each other by a connecting member 15 at one end and electrically connected to different heaters 22 located at different upstream and downstream sides by another connecting member 15 at the other end, respectively. The heater 22 is configured to be connected in a zigzag manner at both ends by the connecting member 15.

In the exhaust gas treatment apparatus 1, the inner wall surface of a casing 20 is shielded from heat by a heat insulating material 19 such as alumina fiber, and a plurality of heaters 22 are arranged inside the casing 20 in the longitudinal direction. Therefore, both the filter 4 and the heater 22 have a structure in which heat is shielded from the outside. Further, a temperature sensor may be provided to detect the temperature of the filter 4 in the casing 20. Heater 2
2 is connected to line 1 to supply power from generator 6.
4 through the controller 10.
Further, a blower (reference numeral 24 in FIG. 3) may be provided on the upstream side of the exhaust gas treatment device 1.

In the exhaust gas processing apparatus 1, the heater 22
And the heater 22 keeps the upstream filter 4R glowing red, so that carbon, soot, and HC containing large particles generated when the engine rotation is small and the load is high is high.
Are collected by a coarse-grained upstream filter 4R, and particulates generated when the engine rotation is large and the load is high are collected by a fine-grained downstream filter 4F. The curate is immediately incinerated in the filter, becomes a gas such as carbon dioxide gas, is discharged to the outside through the filter 4, and the carbon accumulation phenomenon in the filter 4 does not occur. Therefore, since non-uniform deposition and non-uniform combustion of carbon in the filter 4 do not occur, it is possible to prevent the ceramics constituting the filter 4 from burning, such as cracks and cracks. Further, the deposition of carbon on the filter 4, that is, the filter 4
When carbon is not collected by the controller 1
For 0, control for turning off the switch may be performed.

As the porous ceramics constituting the filters 4R and 4F, if the above size is used,
Exhaust gas is exhausted through the pores, but large particulates contained in the exhaust gas can be collected by the upstream filter 4R, and fine particulates can be reliably collected by the downstream filter 4F. . That is, by flowing the exhaust gas from the upstream side of the filter 4, carbon contained in the exhaust gas is collected by the filter 4 and deposited there, but the exhaust gas passes through the heater 22 and the filter 4. The exhaust gas is discharged from the outlet 18 of the exhaust gas treatment device 1 to the outside. The particulates such as carbon, soot, and HC trapped in the filter 4 are supplied to the heater 22.
When electricity is passed through the upstream filter 4R, the upstream filter 4R disposed between the heaters 22 is heated and glows red, so that the carbon is burned there and becomes carbon dioxide gas. The gas passes through the heater 22 and the downstream filter 4F and is discharged from the outlet 18 to the outside.
In addition, the heater 22 is almost always energized by a command from the controller 10, and carbon is always incinerated immediately without excess carbon being deposited in the filter 4, and the filter itself is not overheated locally. Absent.

The exhaust gas treatment device 1 has the above-described configuration and can operate as follows. That is, the exhaust gas is exhausted from the turbine 7 of the turbocharger 5,
The exhaust gas is sent to the exhaust gas processing device 1 through the exhaust passage 2. The exhaust gas flows through the turbine 7 of the turbocharger 5 and is generated by the generator 6. Then, an electric current is supplied to the heater 22 according to a command from the controller 10 to heat the filter 4 to cause the filter 4 to glow red. Further, particulates such as carbon, soot, and HC contained in the exhaust gas are collected by the filter 4, and the particulates collected by the filter 4 are immediately incinerated to be gasified and exhausted from the outlet 18. The filter 4 is in a purified state.

Next, another embodiment of the exhaust gas treatment apparatus according to the present invention will be described with reference to FIG. FIG. 2 is a schematic explanatory view showing another embodiment of the exhaust gas treatment apparatus according to the present invention. In the exhaust gas processing apparatus 1, a casing 20 disposed in an exhaust system such as the exhaust passage 2 is divided into two by a partition plate 16 to form a pair of processing chambers 25 and 26. It is a dual type housing an upstream filter 4R and a downstream filter 4F made of porous ceramics capable of purifying gas. A switching valve 17 is disposed in an inlet passage 27 of each of the processing chambers 25 and 26, and the switching valve 17 is configured to be able to switch between opening and closing such that one of the processing chambers 25 and 26 is opened and the other is closed. ing. The switching valve 17 has a leak hole 21 through which a small amount of exhaust gas can flow into the processing chamber 25 or 26 on the closed side. Further, in the exhaust gas processing apparatus 1, each processing chamber 2
The heater 22 is provided in the upstream filter 4R in each of the heaters 5 and 26.
Are arranged in a non-contact state with each other in a direction intersecting with the flow of the exhaust gas and are sequentially spaced apart from each other in the flow direction. Since the temperature of the downstream filter 4F rises considerably, the heating in the downstream filter 4F occurs There is no need to arrange a heater.

In this embodiment, the power supply means, coarse filter 4R, fine filter 4F, heater 2
Since 2 and the like are substantially the same as those in the above-described embodiment, the duplicate description will be omitted here. The exhaust gas processing apparatus 1 is provided with pressure sensors 13 for detecting the exhaust gas pressure at the inlet of each of the processing chambers 25 and 26. Controller 10
Can control the switching time of the switching valve 17 in response to the detection signal of the pressure sensor 13 and can control the amount of electric power supplied to each heater 22.

The exhaust gas treatment device 1 has the above-described configuration, and can operate as follows. That is, the exhaust gas is exhausted from the turbine 7 of the turbocharger 5,
The exhaust gas is sent to the exhaust gas processing device 1 through the exhaust passage 2. The generator 6 generates electric power by the exhaust gas flowing through the turbine 7 of the turbocharger 5. In response to a command from the controller 10, an electric current is supplied to the heater 22 to heat the filter 4, and the actuator 12 is operated to close the processing chamber 26 and open the processing chamber 25 by the switching valve 17. . Most of the exhaust gas flows in the processing chamber 25, and particulates such as carbon, soot, and HC contained in the exhaust gas are collected by the filter 4 disposed in the processing chamber 25. On the other hand, a small amount of exhaust gas flows into the processing chamber 26 through the leak hole 21, but since the amount of exhaust gas is small, the upstream filter 4 </ b> R is immediately red-heated by the heater 22. Therefore, the particulates such as carbon, soot, and HC trapped by the filter 4 in the processing chamber 26 are immediately incinerated, turned into gas and exhausted from the outlet 18, and the filter 4 is in a purified state.

Although the temperature of the filter 4 in the processing chamber 25 is increased by the heater 22, it is difficult to raise the temperature because a large amount of exhaust gas flows. Particles are deposited. If particulates accumulate on the filter 4, the flow of exhaust gas is suppressed, and the exhaust gas pressure in the processing chamber 25 increases. The exhaust gas pressure is detected by the pressure sensor 13. 17
Issue a command to switch. When the actuator 12 is operated, the switching valve 17 is switched, the processing chamber 25 is closed, and the processing chamber 26 is opened. Therefore, the same exhaust gas processing as described above proceeds. By repeating such processing, the exhaust gas treatment apparatus 1
Performs a function of collecting particulates such as carbon, soot, and HC in one processing chamber, and a function of incinerating the collected particulates in the other processing chamber, and one filter 4 is always purified. In this state, exhaust gas processing can always be performed well.

Next, an embodiment in which the exhaust gas treatment apparatus according to the present invention is mounted on an engine such as a diesel engine will be described.
This will be described with reference to FIG. FIG. 3 is a schematic explanatory view showing one embodiment of a system for treating exhaust gas of a diesel engine incorporating the exhaust gas treating apparatus according to the present invention. The exhaust gas processing apparatus 1 purifies exhaust gas from a diesel engine applied to a moving body such as an automobile, but is substantially the same as that shown in FIG. I do. That is, the exhaust gas treatment device 1
Is a DPF (Diesel Particulate Filter) incorporated in the exhaust passage 2 of the diesel engine 3, particularly disposed in the exhaust passage 2 through which the exhaust gas discharged from the diesel engine 3 flows, and included in the exhaust gas. The filter 4 collects particulates such as carbon, soot, HC, and the like, and incinerates the collected particulates into a red-heated filter 4 to convert the exhaust gas into a gas. In the diesel engine 3, a turbocharger 5 is connected to an exhaust manifold 23. An exhaust gas treatment device 1 for purifying exhaust gas emitted from the engine 3 is incorporated in the exhaust passage 2.

As a power supply source in the exhaust gas treatment device 1, a power generator / motor provided in the turbocharger 5 or a battery storing power generated by the power generator / motor can be used. Since the generator / motor provided in the turbocharger 5 has the same structure as the generator 6 described above, the same reference numerals are given and duplicate explanations are omitted, but the generator / motor in this case is It can function as a generator or an electric motor according to the operation state of the engine by a command. In this embodiment, a generator 6 is used among the generators / motors provided in the turbocharger 5 driven by the exhaust gas energy of the diesel engine 3. The generator 6 generates power when the turbine 7 of the turbocharger 5 is driven by exhaust gas energy. To send electric power to the heater 22, a large amount of electric power is required. However, if electric power is generated by the generator 6 including the permanent magnets 9 on the shaft 11 of the turbocharger 5, for example, electric power of 4 to 8 kW is generated. In addition, since this electric power is converted from the exhaust gas energy, there is no power loss and the electric power can be efficiently used for the heater 22.

In the exhaust gas treatment device 1, the filter 4
If particulates such as carbon, soot, and HC accumulate excessively, the filter 4 is overheated.
In 3, the amount of power supplied to the heater 22 can be controlled while monitoring the exhaust gas pressure in the processing chambers 25 and 26 and, in some cases, monitoring the temperature of the filter 4. That is, the detection signal from the pressure sensor 13 is input to the controller 10, and the controller 10 controls the amount of electric power supplied to the heater 22 in response to the pressure detection signal, and controls the driving of the blower 24 to treat the exhaust gas. Apparatus 1
Can control the amount of air sent to the For example, when the load of the engine is high, the amount of particulates such as carbon contained in the exhaust gas is large, and the temperature of the exhaust gas is also high. In addition, when the engine is operating under a high load, the electric power generated by the generator 6 of the turbocharger 5 becomes large. Therefore, if a part of the electric power is supplied, the particulates collected by the filter 4 are burned. It becomes gas such as carbon dioxide gas and steam.

[0038]

Since the exhaust gas treatment apparatus according to the present invention is constructed as described above, if the heater is energized to constantly glow the upstream filter, carbon and soot contained in the exhaust gas are reduced. , HC, etc., which are generated on the upstream side when the engine rotation is small and the load is large, are collected by the upstream filter, and are formed on the downstream side when the engine rotation is large and the load is large. Fine particles are reliably collected by the downstream filter having an increased contact area, and the filter is not clogged. Then, the filter is constantly heated by the heater, and the particulates such as carbon collected by the filter are immediately burned, converted into gas such as carbon dioxide gas and steam, and released through the filter. Therefore, there is no excessive accumulation of particulates in the filter, no local high-temperature portion is generated in the filter, and no damage such as cracks and burning occurs in the filter. Reliability and durability can be improved.

This exhaust gas processing apparatus is divided into two processing chambers by a partition plate, and the flow of exhaust gas to each processing chamber is switched by a switching valve, so that a large amount of exhaust gas flows into one of the processing chambers. , A small amount of exhaust gas is controlled to flow into the other processing chamber. The filter in which a small amount of exhaust gas flows is quickly heated to a high temperature by the heater, and the trapped particulates such as carbon, soot, and HC are promptly incinerated. While the particulates are incinerated, the switching valve is switched to incinerate the particulates collected by the filter in the other processing chamber. By repeating the switching operation of the switching valve, the filter can always be efficiently purified.

Further, in this exhaust gas treatment apparatus, a generator that generates electric power by operating a turbocharger driven by the exhaust gas energy of the engine can be used as a power supply means. However, the power supplied to the heater is generated by exhaust gas energy using a generator provided in the turbocharger, and the power is insufficient to reduce the filtering function of the filter. There is no loss of engine power. Moreover, since the filter has an electric power that can always supply a current to the heater, the filter is always heated, so that no excessive particulates are deposited on the filter and the filter is clogged. No high-temperature portion is generated locally, and the ceramics of the filter are not burned or damaged.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of an exhaust gas treatment apparatus according to the present invention.

FIG. 2 is a schematic explanatory view showing another embodiment of the exhaust gas treatment apparatus according to the present invention.

FIG. 3 is a schematic explanatory view showing still another embodiment of a system for treating exhaust gas of a diesel engine incorporating the exhaust gas treating apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas processing apparatus 2 Exhaust passage (exhaust system) 3 Diesel engine (engine) 4 Filter 4F Downstream filter 4R Upstream filter 5 Turbocharger 6 Generator 10 Controller 12 Actuator 13 Pressure sensor 15 Connection member 16 Partition plate 17 Switching valve DESCRIPTION OF SYMBOLS 19 Insulation material 20 Casing 21 Leak hole 22 Heater 25, 26 Processing chamber 28 Groove

Continuation of the front page (56) References JP-A-4-50418 (JP, A) JP-A-56-92318 (JP, A) JP-A-3-286120 (JP, A) JP-A-1-136616 (JP) , U) Japanese Utility Model Application Laid-open No. Sho 59-21012 (JP, U) Japanese Utility Model Application Laid-Open Hei 2-31330 (JP, U) Japanese Utility Model Application Hei 2-31331 (JP, U) Japanese Patent No. 2591260 (JP, B2) Japanese Patent Publication No. Hei 2-47248 JP, B2) Tokiko Hei 2-11287 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 46/00-46/54 F01N 3/02-3/038

Claims (6)

(57) [Claims] An exhaust passage through which exhaust gas from an engine flows.
Casing incorporated in, the exhaust gas flow upstream stacked on have roughness of arranged pores side <br/> downstream filter in the casing, it is disposed on the downstream side of the upstream-side filter
Porosity fine downstream filter, it direction intersecting the flow of the exhaust gas across the stacked each upstream filter
A heater electrically disposed in series with the heater in a non-contact state, and power supply means for supplying power to the heater , wherein the upstream filter and the downstream filter are provided.
Is made of non-conductive porous ceramics,
The side filter is made of flat ceramics,
The filter increases the contact area with the exhaust gas
Therefore, many grooves are formed on the upstream and downstream sides of the flat ceramics.
And the heater is connected to the upstream filter in the upstream filter.
Bend from the upstream side to the downstream side in
An exhaust gas treatment device that is connected in a gaseous series and extends . 2. A pair of processing chambers formed by dividing the inside of the casing into two parts by a partition plate, wherein the heater, the upstream filter, and the downstream filter are respectively disposed, and an inlet of each of the processing chambers. 2. The exhaust gas processing apparatus according to claim 1, further comprising a switching valve having a leak hole that opens and closes and allows a small amount of exhaust gas to flow into the processing chamber on the closed side. Wherein the switching valve consists of being switched at a predetermined period set in advance by the timer claim 2
An exhaust gas treatment device according to item 1. 4. A sensor for detecting an exhaust gas pressure at an inlet of each of the processing chambers, and a switching time of the switching valve is controlled in response to a detection signal of each of the sensors, and power is supplied to each of the heaters. Having a controller to control
The exhaust gas treatment device according to claim 2, comprising : Wherein said power supply means, said upstream side fill
Upstream of the casing provided with the filter and the downstream filter.
This is configured with a generator provided in the turbocharger driven by exhaust gas energy of the deployed engine
The exhaust gas treatment device according to claim 1, comprising : 6. The exhaust gas treating apparatus according to claim 1 comprising a heat insulating member is disposed between said casing and said filter.