JP2003003828A - Aftertreatment method and device for diesel exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aftertreatment method and a device for diesel exhaust gas which can purify both of particulate and NOx . SOLUTION: For purifying exhaust gas emitted from a diesel engine by aftertreatment, diesel exhaust gas is made to pass through the first treatment device 26 comprising a filter unit 26A, an adsorption unit 26B and a ternary catalyst unit 26C. Exhaust gas is sent first to the filter unit 26A for scavenging the particulate, then the adsorption unit 26B absorbs NOx when gas pass through the adsorption unit 26B. In the last ternary catalyst unit 26C, the HC are oxidized by reaction with a catalyst, and discharged as H2 O and CO2 being made harmless.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a diesel exhaust gas aftertreatment method and apparatus.

[0002]

2. Description of the Related Art In recent years, with increasing interest in global environmental problems such as airborne particulate matter problems, the amount of particulates contained in exhaust gas discharged from a diesel engine body is reduced. Diesel particulate filter (DPF) for collecting particulates for exhaust gas aftertreatment along with technological research and development
Is being developed. Further, a NOx reduction technique is also being developed because of the concern about air pollution problems and the effects on the human body due to nitrogen compounds (NOx) contained in exhaust gas.

As one of the conventional techniques for post-processing diesel exhaust gas, for example, a NOx storage reduction catalyst is supported on a porous ceramic structure, and particulates in the exhaust gas pass through a porous wall. The catalyst system for diesel vehicles is designed to purify both particulates and NOx by being temporarily trapped on the porous wall during purification and continuously oxidized and purified together with NOx purification. Has been developed (ENGINE TE
CHNOLOGY Vol. 2 No. 6 pp. 46
-47).

[0004]

However, the above-mentioned diesel exhaust gas after-treatment device is a technology based on the premise that it is combined with a direct injection diesel engine equipped with a common rail type electronically controlled fuel injection system, and a usable fuel injection device. Therefore, it is considered that no effect can be expected for exhaust gas purification of a diesel engine in which fuel is supplied using, for example, a row pump, a distribution pump, or a unit pump.

Further, in the above-mentioned conventional apparatus, the performance of the catalyst is deteriorated due to the influence of sulfur oxide (SOx) produced by the combustion of the sulfur content in the fuel in the engine.
The use of gas oil with a low sulfur concentration (50 ppm or less) is essential, and no effect can be expected when this gas oil is not supplied. Therefore, there is a problem that light oil having a specific property is required.

The object of the present invention is to solve the above-mentioned problems in the prior art by using particulates and N.
An object of the present invention is to provide a diesel exhaust gas after-treatment method and device capable of purifying both Ox and Ox.

[0007]

To solve the above problems, the present invention collects particulates contained in the exhaust gas of a diesel engine in order to post-process and purify the exhaust gas discharged from the diesel engine. On the outlet side of the filter unit for collecting, by providing a treatment device comprising an adsorption unit for adsorbing nitrogen oxides and a three-way catalyst unit in this order, and by passing diesel exhaust gas through this treatment device, , It was designed to be purified. It is also possible to provide two sets of processing devices and switch these two sets of processing devices alternately to perform post-treatment and regeneration of exhaust gas.

In the processing apparatus, the exhaust gas is first sent to the filter unit, where the particulates are collected, and the exhaust gas from which the particulates have been removed in this way passes through the next adsorption unit. Nitrogen oxides (NO _x ) contained therein are adsorbed by the adsorption unit. The diesel exhaust gas from which the particulates and nitrogen oxides have been removed in this manner is oxidised by reacting hydrocarbons (HC) with the catalyst in the final three-way catalyst unit, and is rendered harmless as H ₂ O and CO ₂ . Are discharged.

Whether the filter unit reaches the collection limit,
Alternatively, even if the adsorption unit reaches the adsorption limit, the exhaust gas post-treatment described above can be performed again by regenerating the treatment device. To recycle the processor,
If high temperature gas generated by means such as sending fuel and air to the inlet side of the filter unit to ignite it is sent to the filter unit, the particulates trapped there are burned and removed, and the adsorption unit It is possible to desorb the NO _x adsorbed on the. Also,
By supplying HC to the three-way catalyst unit by an appropriate means, desorbed NOx can be favorably treated by the three-way catalyst unit.

That is, CO and CO ₂ produced by the combustion of particulates in the filter unit and NO _x desorbed from the adsorption unit are sent to the three-way catalyst unit together with HC, where H ₂ O and CO are produced by a chemical reaction. ₂
And N _{2 which} are harmless gases and these harmless gases are discharged from the processing equipment.

According to a first aspect of the present invention, there is provided a method for post-treating and purifying exhaust gas discharged from a diesel engine, wherein the exhaust gas is first filtered to collect particulates, and then nitrogen. Diesel exhaust characterized in that nitrogen oxides are adsorbed and removed through an oxide adsorption unit, and then hydrocarbons in exhaust gas from the nitrogen oxide adsorption unit are oxidized through a three-way catalyst unit. A gas aftertreatment method is proposed.

According to a second aspect of the present invention, in a diesel exhaust gas post-treatment device for post-treating and purifying exhaust gas discharged from a diesel engine, the exhaust gas is purified by passing the exhaust gas. And a treatment unit for collecting particulates along the flow direction of the exhaust gas, an adsorption unit for adsorbing nitrogen oxides, and a chemical treatment for hydrocarbons. A diesel exhaust gas after-treatment device is proposed, which is characterized in that a three-way catalyst unit for treating the exhaust gas is arranged in series.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram showing an example of an embodiment of an exhaust gas treatment apparatus according to the present invention, and FIG. 2 is a detailed configuration diagram of the treatment apparatus main body shown in FIG. Exhaust gas aftertreatment device 1
Is a device that is provided, for example, between the outlet end of the exhaust manifold of the diesel engine and the exhaust muffler, and that post-processes and purifies the exhaust gas of the diesel engine, and includes a processing device main body 2 and a control unit 3. ing.
The processing device main body 2 is for purifying particulates, nitrogen oxides (NO _x ), and hydrocarbons (HC) in the exhaust gas of the diesel engine. The control unit 3 is configured by using a microcomputer 31, and the operation of the exhaust gas treatment device 1 is electronically controlled by the control unit 3.

The processing apparatus main body 2 has a passage device 21 for passing exhaust gas, and the passage device 21 is provided with an inlet portion 22 for receiving the exhaust gas and an outlet portion 23 for discharging the exhaust gas. First between the section 22 and the outlet section 23
The passage 24 and the second passage 25 are independently provided side by side. One end of each of the first passage 24 and the second passage 25 is connected to the inlet portion 22 so as to communicate with each other.
2A is configured. The other ends of the first passage 24 and the second passage 25 are connected so as to communicate with the outlet portion 23 to form an outlet side branch portion 23A.

The first and second passages 24 and 25 are provided with a first treatment device 26 and a second treatment device 27 for purifying diesel exhaust gas sent from the inlet portion 22, respectively. The first processing device 26 is a filter unit 26 for collecting particulates in diesel exhaust gas along the flow direction of diesel exhaust gas.
Adsorption units 26B and HC for absorbing A and NO _x
The three-way catalyst unit 26C capable of purifying by the chemical reaction is formed as an integrated unit in series in this order.

The filter unit 26A has a known structure used for this kind of purpose, and the exhaust gas sent to the first processing device 26 through the first passage 24 passes through the filter unit 26A. It is sent to the adsorption unit 26B, and at this time, the filter unit 26A can effectively collect the particulates contained in the exhaust gas.

[0018] adsorption unit 26B are those having the absorption of NO _x material capable of absorbing NO _x, exhaust gas sent from the filter unit 26A is a three-way catalyst unit 26C through the adsorption unit 26B sent to, it has this time a configuration that can be absorbed effectively absorbing material the NO _x contained in the exhaust gas by adsorption unit 26B (not shown). Here, since the absorption of NOx in the absorbent of the adsorption unit 26B is performed well even when the exhaust gas temperature is low, it is effective to discharge NOx even when the exhaust temperature is low as in the case of traffic jam driving. Can be suppressed to

The three-way catalyst unit 26C is provided mainly for oxidizing hydrocarbons (HC) to make them harmless and for detoxifying NOx. The three-way catalyst unit 26C has a well-known configuration whose technology is established in gasoline passenger cars and the like, and the exhaust gas sent from the adsorption unit 26B passes through the three-way catalyst unit 26C to the exhaust muffler side. At this time, the three-way catalyst unit 26C decomposes HC contained in the exhaust gas into water (H ₂ O) and carbon dioxide (CO ₂ ) by a chemical reaction to perform a detoxification process.

The particulates collected by the filter unit 26A are burned and removed in the filter unit 26A as described later when they are accumulated to a predetermined amount, and the HC and carbon monoxide generated at this time are removed. (CO) and carbon dioxide (CO ₂ ) are adsorption units 2
6B to be sent to the three-way catalyst unit 26C. H
When C, CO and CO ₂ pass through the adsorption unit 26B,
Since the high temperature gas produced by the above combustion process is sent to the adsorption unit 26B,
Desorption of O _x is performed, it is possible to reproduce the adsorption unit 26B to reduce the absorption of the NO _x in the results adsorption unit 26B.

Here, in addition to NOx, the NOx absorbent is
It is considered that sulfur oxide (SOx) produced by combustion of the sulfur content in the fuel in the diesel engine is attached, but SOx is desorbed from the NOx absorbent at about 400 ° C, so the NOx absorbent is Almost no deterioration due to the influence of SOx. Therefore, it is not necessary to use a low sulfur component as the fuel. In addition, the filter unit 26A
NOx due to the high temperature of the combustion gas generated during regeneration of NOx
SOx poisoning of the absorber can be eliminated.

NO _x , HC, CO and CO ₂ sent through the adsorption unit 26B are transferred to the three-way catalyst unit 2.
It passes through 6C and is sent to the outlet 23. At this time, since the high temperature gas produced by the above-described combustion process is sent to the three-way catalyst unit 26C, the required chemical reaction is promoted in the three-way catalyst unit 26C, and NO _x , HC, CO, and CO ₂ are harmless H ₂ O , CO ₂ , N ₂ , and the exhaust gas purified in this way is discharged from the outlet 23. As described above, even if excess HC and CO are generated during the regeneration of the filter unit 26A, the three-way catalyst unit 26C acts as an oxidation catalyst, so that HC and CO can be converted into harmless gases and discharged. .

Although the first processing device 26 has been described above, the second processing device 27 also includes the filter unit 27.
A, the adsorption unit 27B, and the three-way catalyst unit 27C are similarly configured, and since the exhaust gas can be purified and regenerated by the same operation principle, the second treatment device 27
A detailed description of is omitted.

The passage of the exhaust gas in the passage device 21 can be switched so that the exhaust gas supplied to the processing apparatus main body 2 can be sent to only one of the first processing apparatus 26 and the second processing apparatus 27. In order to do so, a switching valve device V is provided at the inlet side branch portion 22A.

In the switching valve device V, one end of the second passage 25 is closed and a switching position (first position) shown by a solid line for flowing exhaust gas from the inlet portion 22 to the first passage 24, the first passage 24. One of the switching positions (second position) shown by the dotted line for closing one end and allowing the exhaust gas to flow from the inlet portion 22 to the second passage 25 can be selectively selected.
The switching valve device V uses the first control signal C1 from the control unit 3.
By this, switching control is performed to either the first or second position.

The exhaust gas aftertreatment device 1 includes an air supply device 4
Is provided. The air supply device 4 includes an air tank 41 that stores compressed air therein.
The first air supply passage 42 is provided between the air tank 41 and the first passage 24 so that the compressed air from the first treatment device 26 can be selectively supplied to the inlet side of the first treatment device 26 or the inlet side of the second treatment device 27.
And a second air supply passage 43 is arranged between the air tank 41 and the second passage 25. A first air amount adjusting valve device 44 is provided in the middle of the first air supply passage 42, and a second air amount adjusting valve device 45 is provided in the middle of the second air supply passage 43. The respective operations of the first and second air amount adjusting valve devices 44, 45 are controlled by the second and third control signals C2, C3 sent from the control unit 3, whereby the flow rate of the compressed air is adjusted, and Compressed air is supplied to the inlet side of the first processing device 26 and the second processing device 27.
It can be supplied to either of the entrance sides.

In order to regenerate the filter unit 26A and the filter unit 27A by heating and burning to remove the particulates accumulated on the filter unit 26A or the filter unit 27A, the exhaust gas post-treatment device 1 is equipped with Further, a combustion device 5 is provided.

The combustion device 5 has a first burner nozzle 51 arranged near the inlet of the filter unit 26A in the first passage 24 and a second burner nozzle arranged near the inlet of the filter unit 27A in the second passage 25. The first burner nozzle 51 is supplied with the gaseous fuel stored in the fuel tank 53 through the oil supply passage 54, and the second burner nozzle 52 is connected to the second burner nozzle 52. Fuel is supplied through the oil supply passage 55. The amount of fuel supplied to the first burner nozzle 51 can be adjusted by a first oil amount adjusting valve 56 provided in the middle of the oil supply passage 54, and the amount of fuel supplied to the second burner nozzle 52 can be adjusted by the oil supply passage 55. Second oil amount adjusting valve 5 provided in the middle of
It can be adjusted by 7. First
And the oil amount adjusting operation of the second oil amount adjusting valves 56 and 57 is performed by the fourth and fifth control signals C4 and C5 sent from the control unit 3.
Are controlled respectively by. In the present embodiment, the first burner nozzle 51 has the first air supply passage 42.
The second burner nozzle 52 is disposed in the tip portion 42A corresponding to the first processing device 26 of the second air supply passage 43.
Is disposed in the tip end portion 43A corresponding to the second processing device 27.

The nozzle openings 51A and 52A of the first and second burner nozzles 51 and 52 are arranged so as to supply fuel to the inlets of the filter unit 26A and the filter unit 27A, respectively.
The first burner 58 for igniting the fuel supplied from 1A is arranged near the nozzle 51A, and the second burner 59 for igniting the fuel supplied from the nozzle opening 52A has a nozzle opening 52A. It is located near the.

The first and second burners 58 and 59 are constructed so as to perform an ignition operation by a signal from an igniter 60 controlled by a sixth control signal C6 from the control unit 3.

Therefore, by controlling the first air amount adjusting valve device 44 and the first oil amount adjusting valve 56, compressed air and fuel are supplied from the tip portion 42A and the nozzle port 51A, respectively, to the inlet side of the first processing device 26. And feed the mixture to the first
When ignited by the burner 58, the fuel supplied from the nozzle port 51A is ignited, and the flame generated thereby brings the inlet side of the first processing device 26 into a high temperature state to remove the particulates accumulated in the filter unit 26A. The filter unit 26A can be regenerated by heating and burning. This heating and combustion treatment itself is based on a known treatment method. Further, by heating the inlet side of the first processing device 26 to a high temperature, the NO _x absorbed in the adsorption unit 26B can be desorbed and the adsorption unit 26B can be regenerated.

Temperature sensors 6 and 7 are provided near the inlet and outlet of the filter unit 26A, respectively, and a temperature signal TS1 indicating the air temperature at the inlet side of the filter unit 26A is sent from the temperature sensor 6 to the control unit 3. The temperature sensor 7 sends the temperature signal TS2 indicating the air temperature on the outlet side of the filter unit 26A to the control unit 3. Similarly, temperature sensors 8 and 9 are provided near the inlet and the outlet of the filter unit 27A, and temperature signals TS3 and TS4 are sent from the temperature sensors 8 and 9 to the control unit 3, respectively.

In order to detect the clogging state of the filter unit 26A based on the input / output differential pressure, the first
The pressure sensor 10 is provided on the inlet side of the passage 24, and the pressure sensor 11 is provided on the outlet side of the first passage 24. Further, in order to detect the clogging state of the filter unit 27A based on the input / output differential pressure as well, the pressure sensor 12 is provided on the inlet side in the second passage 25 and the outlet side in the second passage 25. Is equipped with a pressure sensor 13. First detected by pressure sensor 10
Pressure signal P indicating the pressure of the exhaust gas on the inlet side in the passage 24
S1, first passage 24 detected by pressure sensor 11
Inside, the pressure signal PS2 indicating the pressure of the exhaust gas on the outlet side, the pressure signal PS3 indicating the pressure of the exhaust gas on the inlet side in the second passage 25 detected by the pressure sensor 12, and the second detected by the pressure sensor 13. The pressure signal PS4 indicating the pressure of the exhaust gas on the outlet side in the passage 25 is input to the control unit 3.

An oxygen concentration measuring instrument 14 is provided between the filter unit 26A and the adsorption unit 26B in order to detect the oxygen concentration in the exhaust gas flowing from the filter unit 26A into the adsorption unit 26B. An oxygen concentration measuring device 15 is similarly provided between the filter unit 27A and the adsorption unit 27B. An oxygen concentration signal CS1 indicating the oxygen concentration on the inlet side of the adsorption unit 26B detected by the oxygen concentration measuring device 14 and an oxygen concentration signal CS2 indicating the oxygen concentration on the inlet side of the adsorption unit 27B detected by the oxygen concentration measuring device 15. Are input to the control unit 3.

3 to 5 are flowcharts showing a control program executed in the control unit 3.
Next, the operation of the exhaust gas aftertreatment device 1 will be described with reference to FIGS.
Will be described in detail with reference to.

FIG. 3 shows a main flow chart of control. In step S1, it is judged whether or not the first processing device 26 needs to be regenerated when the first processing device 26 is purifying exhaust gas. When it is determined that the first control device 26 is reproduced, the first control process for reproducing the first processing device 26 is executed.

FIG. 4 shows a detailed flow of the first control process executed in step S1. Step S
When execution of step 1 is started, step S11 is entered, in which the switching valve device V determines whether or not the exhaust gas is flowing through the first processing device 26 and the first processing device 26 is purifying the exhaust gas. It is determined by whether or not it is switched to the 1 position. When the first processing device 26 is purifying the exhaust gas, the determination result of step S11 is YES, and the process proceeds to step S12 where the differential pressure of the exhaust gas before and after the first processing device 26 is measured. Then, the process goes to step S13. In step S13, it is determined whether or not the value of the differential pressure of the exhaust gas before and after the first processing device 26 measured in step S12 is larger than a predetermined value at which regeneration by combustion of the filter unit 26A should be started.

Step S13 is a step of determining whether or not the filter unit 26A is in a clogged state based on whether or not the value of the differential pressure across the first processing device 26 is larger than a predetermined value. is there. That is, the collection amount of particulates in the filter unit 26A is large,
If the filter unit 26A is in a clogged state, the value of the differential pressure of the exhaust gas before and after the first processing device 26 becomes larger than a predetermined value, and the determination result of step S13 is YE.
It becomes S and enters step S14. On the other hand, when the amount of collected particulates in the filter unit 26A is small and the filter unit 26A is not clogged, the value of the differential pressure before and after the first processing device 26 becomes smaller than the predetermined value, and thus, in step S13. The determination result is NO, and the process goes to step S15.

In step S15, the adsorption unit 26B is saturated based on whether or not the estimated NOx absorption amount estimated to be absorbed by the adsorption unit 26B based on the engine operating state is larger than a predetermined value. It is determined whether or not there is. If the adsorption amount of NOx in the adsorption unit 26B is small and the adsorption unit 26B is not saturated, the estimated NOx absorption amount becomes smaller than the predetermined value, the determination result of step S15 is NO, and the process returns to step S1. On the other hand, NOx in the adsorption unit 26B
When the adsorption unit 26B is saturated with a large amount of absorbed NOx, the estimated NOx absorption value becomes larger than a predetermined value,
The result of the determination in step S15 is YES and step S
Enter 14.

In step S14, the switching valve device V is set to the second
It is switched to the position, whereby the inflow of exhaust gas into the first processing device 26 is stopped, and the exhaust gas is transferred to the second processing device 2
7 and is put into a state where it is post-processed by the second processing device 27. Next, in step S16, in which the first
The reproduction process of the processing device 26 is performed.

FIG. 5 shows a detailed flowchart of the reproduction process in step S16. Referring to FIG. 5, when the execution of step S16 is started, step S31 is entered, and here, the supply of fuel and air to the first processing device 26 is started. In step S32, the first
The burner 58 is ignited, which causes the mixture of fuel and air to begin burning. In step S33, the supply amounts of fuel and air to the inlet side of the first processing device 26 are adjusted so that the particulates accumulated in the filter unit 26A for regenerating the filter unit 26A can be burned.

After the supply amount of fuel and air is adjusted in step S33 and the regeneration process of the filter unit 26A is started, it is determined in step S34 whether the regeneration process of the filter unit 26A has passed a predetermined time T1. To be done. When the fixed time T1 has not elapsed, it is determined that the regeneration process of the filter unit 26A has not been completed, the determination result of step S34 is NO, and the process proceeds to step S35, in which the engine is stopped. It is determined whether or not there is. When the engine is not in the stopped state and is operating, the determination result of step S35 is NO, and the process is returned to step S33, and it is determined that the regeneration process of the filter unit 26A is completed. Step S until a certain time T1 has passed
The determination process at 34 is repeated.

When it is determined that the fixed time T1 has elapsed, it is determined that a sufficient amount of heat has been supplied to the filter unit 26A, the determination result of step S34 is YES, and the process proceeds to step S36. In step S36, regeneration of the adsorption unit 26B and NO in the three-way catalyst unit 26C are performed.
In order to purify x, CO, CO ₂ and HC, a fuel and oxygen concentration measuring device for the inlet side of the first treatment device 26 so that appropriate combustion can be performed at the inlet side of the first treatment device 26. The supply amount of air is adjusted based on the oxygen concentration signals CS1 and CS2 from 14 and 15, and is adjusted to a predetermined air-fuel ratio.

By adjusting the supply amounts of fuel and air in step S36, regeneration of the adsorption unit 26B and NOx, CO, CO in the three-way catalyst unit 26C are performed.
After the processes for purifying ₂ and HC are started, it is determined in step S37 whether or not these processes have passed the predetermined time T2. If the predetermined time T2 has not elapsed, it is determined that the process of regenerating the adsorption unit 26B and the purification of NOx, CO, CO ₂ and HC in the three-way catalyst unit 26C has not been completed, and step S37. The result of the determination is NO, and the process goes to step S38. In step S38, it is determined whether the engine is stopped. When the engine is not in the stopped state and is operating, the determination result of step S38 is NO, and the process is returned to step S36. The regeneration of the adsorption unit 26B and the three-way catalyst unit 26C are performed. The determination process in step S37 is repeated until the fixed time T2 when it is determined that the purification of NOx, CO, CO ₂ and HC is completed.

When it is determined that the predetermined time T2 has elapsed, the adsorption unit 26B is regenerated and the three-way catalyst unit 26 is regenerated.
It is determined that the process of purifying NOx, CO, CO ₂ and HC in C has ended, the determination result in step S37 is YES, and step S39 is entered, in which the first burner 58 is extinguished, and step S16 Return to.

If the engine is stopped in step S35, step S39 is entered, whereby the regeneration process for the filter unit 26A is interrupted. Similarly, when the engine is stopped in step S38, step S39 is entered and the regeneration process of the filter unit 26A is interrupted.

Returning to FIG. 4, after the reproduction process of the first processing device 26 is completed in step S16 as described above, the process goes to step S17, in which the first processing device 26 is performed.
Is set in the collection standby state, and the process returns to step S1.

In step S11, the first processing device 2
When the exhaust gas is not flowing to 6 and the first processing device 26 is not purifying the exhaust gas, the determination result of step S11 is NO, and the process proceeds to step S18. Step S1
In No. 8, the first processing unit 26 when the engine was stopped last time
Was determined to be in the middle of the reproduction process, and when the first processing device 26 was not in the middle of the reproduction process when the engine was stopped last time, that is, when the reproduction process of the first processing device 26 was not interrupted. The determination result is NO, and the process returns to step S1. If the first processing device 26 was in the middle of the reproduction process when the engine was stopped last time, that is, if the reproduction process of the first processing device 26 was interrupted, step S18
The result of the determination is YES, the process goes to step S16, and the reproduction process of the first processing device 26 is started.

Returning to FIG. 3, after the reproduction process of the first processing device 26 is completed in step S1 by the above operation, step S2 is entered. In step S2, it is determined whether or not the second processing device 27 needs to be regenerated when the second processing device 27 is purifying the exhaust gas, and when it is determined that the second processing device 27 needs to be regenerated, the second processing device 27 is determined. The second control process for reproducing is executed. The reproduction process of the second processing device 27 executed here is the first process described in step S1.
Since it is performed in the same manner as the reproduction process of the processing device 26, detailed description of the reproduction process of the second processing device 27 performed in step S2 is omitted.

As described above, in the exhaust gas aftertreatment device 1, the regeneration process of the first and second treatment devices 26 and 27 is
Since the high temperature gas generated by burning the fuel at the inlet side of each processing device can be performed simply by flowing into each processing device, control on the engine side such as post injection is not required, and the configuration is complicated. It has the advantage of not causing it.

In step S2, the first processing unit 26
After the reproduction processing of the second processing device 27 is completed in the same manner as the reproduction processing of step S3, step S3 is entered and it is determined here whether the engine is in the stopped state. If the engine is not in the stopped state and is operating, the determination result in step S3 is NO, the process returns to step S1, and the regeneration process of the processing device body 2 is performed again. Step S3
When the engine is in the stopped state in step S4, the determination result is YES, and the control program for performing the regeneration processing of the processing device body 2 by the control unit 3 ends.

The exhaust gas aftertreatment device 1 is controlled by the control unit 3 as described above, and the first or second treatment device 2 is operated.
While the exhaust gas purification process is being performed in any one of the first and second processing devices 26 and 26,
Since the regeneration treatment of No. 7 can be performed, each regeneration treatment of the first and second treatment devices 26 and 27 is constant without being influenced by the flow rate of exhaust gas, temperature, property, etc. It can be performed under the conditions of. Therefore, the first and second processing devices 26, 2 can be stably and in a short time.
Each playback of 7 can be performed. In addition, since it is a switching type, it is possible to reduce the energy consumption during the regeneration process, and it is possible to expect an improvement in fuel consumption.

[0053]

The effects of the present invention are as follows. (1) Since the configuration for post-processing diesel exhaust gas using a three-way catalyst is adopted, control of the engine side such as post injection is not required, and the structure of the diesel exhaust gas post-processing device can be complicated. Absent. (2) Although hydrocarbons (HC) and carbon monoxide (CO) are generated when the particulate matter accumulated in the filter unit is burned to regenerate the filter unit, the three-way catalyst unit acts as an oxidation catalyst. , HC, CO
Can be converted into harmless gas and discharged. (3) In addition to NOx, SOx generated by combustion of sulfur in fuel in the diesel engine may be attached to the nitrogen oxide adsorption unit.
Since Ox desorbs from the adsorption unit at about 400 ° C,
In the adsorption unit, there is almost no deterioration due to the influence of SOx. Therefore, it is not necessary to use a low sulfur component as the fuel. Further, SOx poisoning of the adsorption unit can be eliminated by the high temperature of the combustion gas generated when the filter unit is regenerated. (4) Since NOx is absorbed into the adsorption unit satisfactorily even when the exhaust gas temperature is low, NOx emission can be effectively suppressed even when the exhaust temperature is low as in the case of traffic congestion.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an embodiment of an exhaust gas treatment device according to the present invention.

FIG. 2 is a detailed configuration diagram of the processing apparatus main body shown in FIG.

FIG. 3 is a flowchart showing a control program executed by the control unit shown in FIG.

FIG. 4 is a detailed flowchart of the first control processing step of FIG.

5 is a detailed flowchart of the reproduction processing steps of FIG.

[Explanation of symbols]

1 Exhaust gas aftertreatment device 2 Processing device body 3 control unit 4 Air supply device 5 Combustion equipment 6, 7, 8, 9 Temperature sensor 10, 11, 12, 13 Pressure sensor 14, 15 Oxygen concentration measuring instrument 21 passage device 24 First passage 25 Second passage 26 First Processing Device 26A, 27A filter unit 26B, 27B adsorption unit 26C, 27C three-way catalyst unit 27 Second processing device 31 Microcomputer 41 air tank 53 Fuel tank C1 first control signal C2 second control signal C3 Third control signal CS1, CS2 oxygen concentration signal PS1, PS2, PS3, PS4 Pressure signal TS1, TS2, TS3, TS4 Temperature signal V switching valve device

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/02 F01N 3/02 331Q 331R B01D 53/94 3/08 A F01N 3/08 B 3/24 B 3/24 C 3/28 301G 3/28 301 3/36 J 3/36 B01D 53/36 104A (72) Inventor Yasuo Yokota 3-13-26, Yasumimachi, Higashimatsuyama City, Saitama Prefecture Bosch Automotive Systems Higashimatsuyama Factory ( 72) Inventor Yuji Furuya 3-13-26, Yasumicho, Higashimatsuyama City, Saitama Prefecture Bosch Automotive Systems Co., Ltd. Higashimatsuyama Plant (72) Inventor, Takeshi Miyamoto 3--13, Yasumimachi, Higashimatsuyama City, Saitama Prefecture Bosch Corporation Automotive System Higashimatsuyama Factory (72) Inventor Hiroshi Oikawa 3-13-26, Yasumicho, Higashimatsuyama City, Saitama Prefecture Bosch Automotive Systems Hokumatsuyama Factory F-term (reference) 3G090 AA02 BA02 CA01 CA02 CB04 CB07 CB23 DA 04 DA13 EA02 3G091 AA18 AB03 AB06 AB09 AB12 AB13 AB15 AB16 BA07 BA11 BA14 CA02 CA18 CA22 CA26 EA17 EA32 EA34 FB14 FC01 GA06 HA07 HA16 HA20 HA23 HA36 HA37 HA42 HB02 4D048 AA06 AA14 BC01 CC25 CC32 CC33 CD05

Claims (2)

[Claims] 1. A method for post-processing and purifying exhaust gas discharged from a diesel engine, wherein the exhaust gas is first filtered to collect particulates and then passed through a nitrogen oxide adsorption unit. A diesel exhaust gas post-treatment method, wherein nitrogen oxides are adsorbed and removed, and then hydrocarbons in the exhaust gas from the nitrogen oxide adsorption unit are oxidized through a three-way catalyst unit. 2. A diesel exhaust gas post-treatment device for post-treating and purifying exhaust gas emitted from a diesel engine, comprising a treatment device for purifying the exhaust gas by passing the exhaust gas. The processing device comprises a filter unit for collecting particulates along the flow direction of the exhaust gas, an adsorption unit for adsorbing nitrogen oxides, and a ternary device for chemically treating hydrocarbons. A diesel exhaust gas post-treatment device comprising a catalyst unit arranged in series.