JP4515217B2 - Exhaust gas purification device control method - Google Patents

Description

The present invention relates to an apparatus for purifying exhaust gas of an internal combustion engine such as a diesel engine, a gas engine, a gasoline engine, or a gas turbine engine. In particular, the present invention is installed in an exhaust passage and mainly removes particulate matter such as nitrogen oxides and soot. The present invention relates to a method for controlling an exhaust gas purifying apparatus.

  Substances that are subject to exhaust gas purification are particulate substances such as nitrogen oxides, carbon monoxide, unburned hydrocarbons, and soot. Various devices for purifying these substances have been developed in the past.

  As a device for reducing nitrogen oxide (NOx), a denitration device that selectively reduces nitrogen oxide by installing a reduction catalyst using ammonia or urea as a reducing agent in the exhaust passage has been put into practical use. Yes. In addition, relatively small gas engines and gasoline engines for automobiles have developed three-way catalysts capable of simultaneously decomposing nitrogen oxides, carbon monoxide (CO), and unburned hydrocarbons (HC). Contributes to effective gas purification.

  However, the three-way catalyst exhibits a purification action effectively when operated within the stoichiometric air-fuel ratio or a range close thereto, but is effective under other conditions, particularly in exhaust gas with excessive air (oxygen). It has been found that it does not work. In order to cope with this, in a gas or gasoline engine operated in an excessive air state, nitrogen oxide is temporarily stored in the storage material during the operation in the above-described excessive air (oxygen) condition, and then the excess fuel is stored. A nitrogen oxide storage catalyst system that releases and reduces the stored nitrogen oxide by operating under conditions has been put into practical use.

  However, it has been found that the nitrogen oxide storage catalyst system poisons the catalyst by sulfur oxide (SOx) in the exhaust gas derived from the sulfur component in the fuel and the purification ability of nitrogen oxide decreases rapidly. Therefore, it is currently used only in engines that use low sulfur content fuel.

  Moreover, an electrostatic precipitator and a DPF have been put into practical use for removing particulate substances such as soot. The DPF physically captures particulate matter with a filter and incinerates and removes the captured particulate matter with an electric heater or the like. Recently, however, a catalytic component having an oxidizing action is removed by a particulate filter. A DPF that can be supported on a substrate and continuously remove particulate matter has also been developed. In addition, the patent document considered to be strongly related to the present invention could not be found.

  As described above, the three-way catalyst cannot exert its catalytic function in an internal combustion engine that is operated under an excess air condition, and has been put into practical use in a small gas engine or an automobile gasoline engine. In the nitrogen oxide storage catalyst system, it is difficult to effectively exhibit its purification ability in exhaust gas containing sulfur oxide and particulate matter.

Industrial internal combustion engines and marine internal combustion engines are mostly operated under excessive air conditions, and there is a demand for a control method for an exhaust gas purification device that can sufficiently perform performance even in such exhaust gases. .

  A denitration device that selectively reduces nitrogen oxides using ammonia, urea, etc. is applied to relatively large industrial internal combustion engines and combustion equipment, but the device itself is large and very expensive. In addition, the maintenance cost of the reducing agents ammonia and urea is high. Furthermore, there is a high possibility that ammonia that is not consumed is released into the atmosphere.

(Object of invention)
An object of the present invention is to remove nitrogen oxides, particulate matter such as soot, carbon monoxide, and unburned hydrocarbons in exhaust gas in an internal combustion engine that operates mainly under an excess air condition, and lowers its purification capacity. It is an object of the present invention to provide a method for controlling an exhaust gas purifying apparatus that can be maintained without causing it to occur.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present application branches an exhaust passage of an internal combustion engine into a plurality of branch exhaust passages via a branch portion, and the branch passage includes an exhaust passage as each branch exhaust. An inlet side switching valve is provided that is switchably connected to the passage, and in each branch exhaust passage, nitrogen oxide is temporarily adsorbed in an excess air atmosphere, and the adsorbed nitrogen oxide is removed in a temperature rising or reducing atmosphere. A nitrogen oxide adsorbing material is provided, and an air supply means is provided upstream of the exhaust of the nitrogen oxide adsorbing material so that the air supplied from the air supply means is heated or reduced to desorb the adsorbed material. The adsorbed substance desorbing means is composed of the air supply means, the fuel supply means, and the ignition means, and each branch exhaust passage joins at a junction at the downstream side of the nitrogen oxide adsorbent. And the merging portion of the internal combustion engine A regeneration gas inlet passage and the atmosphere open passage connecting the air passage, a method of controlling the exhaust gas purifying device connected switched freely by the outlet side switching valve, said nitrogen oxide adsorbing provided in each branch exhaust passage The temperature detection means is provided upstream of the exhaust of the material, and the adsorption amount detection means for detecting the adsorption amount by the nitrogen oxide adsorbent is disposed on the exhaust downstream side of the nitrogen oxide adsorbent, and at least one in the normal operation state Exhaust gas from the internal combustion engine is caused to flow into the branch exhaust passage, and the amount of adsorption by the nitrogen oxide adsorbent is detected by the adsorption amount detection means. When the amount of adsorption reaches a predetermined amount, the exhaust gas to the branch exhaust passage is exhausted. The gas inflow is shut off by switching the inlet side switching valve, and the air supply means and the adsorbed substance desorbing means are operated to perform a regeneration operation, and the temperature detecting means performs a predetermined temperature and reducing atmosphere. The regeneration gas containing the desorbed substance flows into the cylinder of the internal combustion engine through the regeneration gas introduction passage and the intake passage by switching the outlet side switching valve, and the adsorption amount detection means When it is detected that all the adsorbed substances in the oxide adsorbent have been desorbed, the adsorbent desorbing means is stopped, and control is performed to return to the normal operation state by connecting to the exhaust passage by switching the inlet side switching valve. In addition, all the branch exhaust passages are configured not to perform the regeneration operation at the same time.

  In the adsorbed substance desorbing means, the flow rate of air supplied from the air supply means is preferably 20% or less of the exhaust gas flow rate of the internal combustion engine. When the adsorbed substance desorbing means is a combustion device, the adsorption NOx It is preferable that the combustion conditions for generating a reducing atmosphere for desorbing are in the range of 0.4 to 0.9 in terms of excess air.

  In the case of an internal combustion engine with a supercharger, the air supply means of the nitrogen oxide desorbing means may be connected to the outlet portion of the compression part of the supercharger and use compressed air from the supercharger. it can. The regeneration gas returned to the internal combustion engine can be mixed with intake air at the inlet of the supercharger or mixed at the outlet of the supercharger.

  Further, an exhaust gas cooling means is disposed upstream of the adsorbed substance desorbing means, and a temperature sensor for measuring the temperature of the exhaust gas coming out of the exhaust gas cooling means is provided. The exhaust gas temperature that comes out can be set arbitrarily.

First, the basic operation and control in the exhaust gas purification apparatus will be briefly described. The branch exhaust passage connected to the exhaust passage by the inlet side switching means is in a normal operation state in which the adsorbed substance desorbing means is stopped. The nitrogen oxide in the exhaust gas discharged from the internal combustion engine is adsorbed by the nitrogen oxide adsorbent. In addition, unburned components such as hydrocarbons and carbon monoxide in the exhaust gas are caused by the oxidation action of at least one catalyst component selected from catalysts contained in the nitrogen oxide adsorbent, such as Pt, Pa, and Rh. Oxidized, detoxified and discharged into the open air passage. When the adsorption amount of the nitrogen oxide adsorbent reaches a predetermined amount (for example, a saturation amount), the exhaust gas from the internal combustion engine is shut off by switching the inlet side switching means, the adsorbed substance desorbing means is operated, and the regeneration operation is performed. . That is, nitrogen oxide is desorbed from the nitrogen oxide adsorbent, but the operation different from that of the first invention is that the regeneration gas generated by the regeneration operation is generated by the internal combustion engine via the outlet side switching means and the regeneration gas introduction passage. To the intake passage of the internal combustion engine, mixed with the intake air of the internal combustion engine and introduced into the cylinder, and in the excess fuel region in the combustion in the cylinder, the remaining desorbed nitrogen oxides are reduced, and the remaining unburned substances Is oxidized and removed.

The present invention having such basic functions has the following effects.
(1) In an internal combustion engine that is operated under excessive air conditions, during normal operation, nitrogen oxides in exhaust gas are efficiently adsorbed by the nitrogen oxide adsorbent, and hydrocarbons and Carbon monoxide is oxidized and rendered harmless, and desorbed nitrogen oxides are reduced and removed by the above-mentioned catalyst by regeneration operation, or in addition to this, they are mixed with the intake air of the internal combustion engine and reduced in an excess fuel atmosphere in the cylinder. Can be removed. Further, poisoning of the nitrogen oxide adsorbent by sulfur oxide can be prevented, and the purification ability can be maintained.

(2) The exhaust passage is branched into two or more branch exhaust passages, the exhaust gas from the internal combustion engine or the like is allowed to flow through at least one branch exhaust passage, and the remaining branch exhaust passage is shut off the exhaust gas for regeneration operation. It can be carried out. Thereby, since the exhaust gas to the branch exhaust passage in the regeneration operation state is shut off, the air amount into the branch exhaust passage in the regeneration operation state can be freely set regardless of the exhaust gas amount of the internal combustion engine. . Therefore, independent of the branch exhaust passage in the normal operation state, the amount of air in the branch exhaust passage in the regeneration operation state can be set small, and the energy consumed to desorb the nitrogen oxide from the nitrogen oxide adsorbent (fuel flow rate) ) Can be set low, and fuel cost savings can be achieved.

(3) If a heating resistor such as an electric heater is provided as the adsorbing substance desorbing means, the temperature can be reliably and rapidly increased.

(4) If the temperature raising means and the reducing agent supply means are provided as the adsorbing substance desorbing means, the nitrogen oxide and sulfur oxide can be desorbed from the nitrogen oxide adsorbing material by introducing the reducing agent. It can be done efficiently.

(5) When the fuel supply means is provided as the adsorbing substance desorbing means, the supplied fuel serves as a reducing agent and is oxidized on the catalyst having an oxidizing action contained in the nitrogen oxide adsorbent. You can use the heat generated when

(6) When the adsorbed substance desorbing means includes a fuel supply means and a catalyst having an oxidizing action arranged downstream of the fuel supply means, the oxidizing substance contained in the nitrogen oxide adsorbing material is provided. When it is oxidized on the catalyst, it generates heat, and this heat can be used for desorption.

(7) If a combustion device comprising an air supply means, a fuel supply means and an ignition means is provided as the adsorbed substance desorption means, the desorption action is performed using combustion, so the temperature is instantly raised to a higher temperature. In addition, it is possible to flexibly cope with various conditions by adjusting the air flow rate and the fuel flow rate. Furthermore, the combustion supply device and the devices (combustion tanks, metering devices, etc.) associated therewith can be shared with the internal combustion engine, thereby reducing the size and cost.

(8) In the adsorbing substance desorbing means, when the air flow rate supplied from the air supply means is reduced so as to be 20% or less of the exhaust gas flow rate of the internal combustion engine, the reducing agent decreases as the air flow rate decreases. It is economical because it requires less combustion. In particular, it is more economical to set the exhaust gas flow rate to 10% or less.

(9) In the combustion apparatus provided as the adsorbent desorption means, the combustion conditions for generating a reducing atmosphere for desorbing the adsorbed NOx are in the range of 0.4 to 0.9 in terms of excess air ratio. By doing so, it is possible to efficiently desorb the adsorbed nitrogen oxides, sulfur oxides and the like by generating a reducing atmosphere with excess fuel.

(10) When the particulate filter is disposed upstream of the nitrogen oxide adsorbent, particulate matter in the exhaust gas is removed before flowing into the nitrogen oxide adsorbent, so that the nitrogen oxide adsorbent The nitrogen oxide adsorption rate is not affected by the particulate matter, and the nitrogen oxide can be favorably adsorbed. When the trapped amount of particulate matter in the particulate filter becomes saturated, the back pressure will increase. However, when the nitrogen oxide adsorption amount of the nitrogen oxide adsorbent becomes saturated, the regeneration operation is performed. In addition, the particulate matter can be removed by incineration by increasing the temperature of the adsorbing substance desorbing means, and the particulate filter can be regenerated.

(11) By forming the shape of the nitrogen oxide adsorbing material itself into a physical shape capable of capturing particulate matter, the purification device can be kept small while being configured to be able to remove particulate matter. it can.

(12) When a sulfur oxide adsorbent is disposed upstream of the nitrogen oxide adsorbent, sulfur oxide and nitrogen oxide are adsorbed on the sulfur oxide adsorbent and nitrogen oxide adsorbent, respectively, and each is efficiently Can be adsorbed. The sulfur oxide adsorbent can be desorbed and regenerated by simultaneously raising the temperature when the adsorption operation of the nitrogen oxide adsorbent becomes saturated and the regeneration operation is performed. Desorption in a reducing atmosphere is more effective.

(13) As an air supply source of the air supply means, a separate compressor, blower or the like can be provided. By using a part of the compressed air from the supercharger, the separate air supply is provided. No source is required, and the device can be miniaturized.

(14) If a catalyst having an oxidation function is arranged on the exhaust gas downstream side of the nitrogen oxide adsorbent, unburned hydrocarbons and carbon monoxide can be satisfactorily oxidized and removed even in a relatively low temperature state.

(15) If an exhaust gas cooling means is disposed upstream of the adsorbed substance desorbing means and a temperature sensor is provided, the temperature of the exhaust gas flowing into the nitrogen oxide adsorbent is determined by the nitrogen oxide adsorbent. It is possible to control the temperature so that the adsorption capacity of the internal combustion engine and the fuel device can be exerted most, and it can be satisfactorily removed in any operating state of the internal combustion engine and the fuel device. This also makes it possible to deal with adsorbents having various active temperature zones.

(16) If the regeneration gas cooling means is disposed in the regeneration gas introduction passage between the outlet side switching means of the merging portion and the intake passage of the internal combustion engine, the high temperature exhaust gas at the time of regeneration is cooled before the internal combustion engine Since it is mixed with the intake air, it is possible to suppress an excessive increase in the temperature of the intake air and to prevent the influence on the emission and fuel consumption.

(17) When using a fuel containing a sulfur component, the gas obtained by regenerating the nitrogen oxide adsorbent contains a high concentration of sulfur oxide. If a desulfurization device is provided in the regeneration gas introduction passage between the intake passages, the high-concentration sulfur oxide can be removed before flowing into the internal combustion engine, and the durability of the internal combustion engine can be maintained. .

[First reference example of exhaust gas purification device]
(Configuration of exhaust gas purification device)
FIG. 1 shows a first reference example of an exhaust gas purifying apparatus. As an internal combustion engine 1, a diesel engine, a gas engine, a gasoline engine, a gas turbine engine, or the like is used. The internal combustion engine 1 includes an intake manifold 2 and an exhaust manifold 4. The exhaust manifold 4 is connected to the intake manifold 2, the exhaust passage 5 is connected to the exhaust manifold 4, and the exhaust gas purification apparatus A having the configuration described below is connected to the exhaust passage 5. .

  The exhaust downstream side of the exhaust passage 5 is branched into first and second branch exhaust passages 7a and 7b via a branch portion 6, and the exhaust downstream side of both branch exhaust passages 7a and 7b is connected to the junction portion 8. To the atmosphere opening passage 9. The branch section 6 is provided with an inlet side switching valve 12 as an inlet side switching means. By switching the inlet side switching valve 12, the exhaust gas from the exhaust passage 5 is supplied to one of the branch exhaust passages 7a and 7b. The flow is selectively performed and the other is blocked.

  In each of the branch exhaust passages 7a and 7b, an adsorbed material desorbing means 10 and a nitrogen oxide adsorbing material (hereinafter referred to as “NOx adsorbing material”) 11 are spaced in the exhaust flow direction in order from the exhaust upstream side. Each is arranged.

  The NOx adsorbent 11 can efficiently adsorb nitrogen oxides (hereinafter referred to as “NOx”) even in an excess air atmosphere, and the adsorbed NOx when heated to a predetermined temperature or in a reducing atmosphere. Has the property of desorbing. The NOx adsorbent 4 includes a catalyst made of a noble metal such as Pt, Pa, Rh, and the catalytic action of these catalyst components causes carbon monoxide (hereinafter referred to as “CO”) or hydrocarbon (hereinafter referred to as “HC”). The unburned components such as NOx) and the NOx desorbed from the nitrogen oxide adsorbing material 11 in the reducing atmosphere are reduced. Furthermore, the shape of the nitrogen oxide adsorbing material 11 itself is a shape suitable for capturing particulate matter.

  In the present embodiment, as the adsorbed substance desorbing means 10, a combustion device including a fuel nozzle 21, an air supply means 22 and an ignition device 23 is used. The fuel nozzle 21 is connected to the fuel metering device 15, The air supply means 22 is connected to the air metering device 16.

  An air supply source 17 such as a compressor is connected to the air metering device 16 to supply combustion air, and a fuel tank 18 is connected to the fuel metering device 15 to supply fuel. It has become so. An electronic control unit (ECU) 25 is connected to the fuel metering device 15 and the air metering device 16 to control the operation.

(Operation of the first reference example)
When the internal combustion engine 1 is operated, the flow path of the exhaust gas is switched by the inlet side switching valve 12 so that one of the branched exhaust passages 7a and 7b is brought into a normal operation state in which the exhaust gas of the internal combustion engine 1 flows. Is in a regeneration operation state in which the exhaust gas is shut off.

  In the state of FIG. 1, the first branch exhaust passage 7a is in a normal operation state, and the adsorbed substance desorbing means 10 is stopped in the first branch exhaust passage 7a, and NOx in the exhaust gas is converted into NOx adsorbent. 11 is adsorbed. At the same time, unburned components such as CO and HC are oxidized and rendered harmless by the catalyst having an oxidation function contained in the NOx adsorbent 11. Furthermore, if the shape of the NOx adsorbent 11 is a shape suitable for capturing particulate matter, the particulate matter can also be physically captured by the NOx adsorbent 11.

  On the other hand, in the second branch exhaust passage 7b in the regeneration operation state, the adsorbed substance desorbing means 10 is operated, and the NOx adsorbent is burned with the air from the fuel nozzle 21 by the air from the air supply means 22. 11 is supplied with high-temperature exhaust gas, adsorbed NOx is desorbed from the NOx adsorbent 11, and the desorbed NOx is reduced and removed by the action of the catalyst contained in the NOx adsorbent 11. The exhaust gas from the exhaust passage 7 a is merged and discharged from the atmosphere opening passage 9.

  The second branch exhaust passage 7b in the regeneration operation state is in a state in which the exhaust gas from the internal combustion engine 1 is shut off and is operated independently from the first branch exhaust passage 7a in the normal operation state. Since the regeneration operation is performed by the fuel supply and air supply from the separation unit 10, the amount of adsorbed material desorption air can be set regardless of the amount of exhaust gas from the internal combustion engine 1. The fuel supply amount can be saved. The flow rate of air supplied from the air supply means 22 during the regeneration operation is suppressed to 20% or less, preferably 10% or less of the exhaust gas of the internal combustion engine. As a result, the amount of fuel from the combustion nozzle 21 can be reduced, which is economical.

  When the NOx adsorption amount of the NOx adsorbent 11 reaches a predetermined amount (for example, a saturation amount) in the first branch exhaust passage 7a in the normal operation state, the inlet side switching valve 12 is switched to the second branch exhaust passage 7b side. Then, the adsorbed substance desorbing means 10 in the second branch exhaust passage 7b is stopped, and at the same time, the adsorbed substance desorbing means 10 in the first branch exhaust path 7a is activated. That is, the first branch exhaust passage 7a is set in the regeneration operation state, and at the same time, the second branch exhaust passage 7b is set in the normal operation state.

  When SOx is contained in the exhaust gas, the NOx adsorbent 11 is made of a material that hardly adsorbs SOx, or even when adsorbed, the NOx adsorbent 11 reaches the SOx desorption temperature. Is desorbed from the NOx adsorbent 11 by raising the temperature and, if necessary, creating a reducing atmosphere. Thereby, poisoning of the NOx adsorbent 11 is prevented.

[ First embodiment of exhaust gas purifying apparatus for carrying out control method according to present invention and control method therefor ]
FIG. 2 shows a first embodiment for carrying out the control method according to the present invention . Compared with the reference example shown in FIG. 1, the junction 8 of both branch exhaust pipes 7a and 7b and the downstream of the junction 8 The other configurations are the same as those in the first embodiment, and the same components are denoted by the same reference numerals, and detailed description of the same structure is omitted.

  An outlet side switching valve 31 is disposed at the junction 8 of both branch exhaust pipes 7a and 7b, and a regeneration gas introduction passage 30 connected to the intake passage 3 of the internal combustion engine 1 is connected in addition to the atmosphere release passage 9. By switching the outlet side switching valve 31, either one of the two branch exhaust passages 7a and 7b is connected to the atmosphere opening passage 9, and the other is connected to the regeneration gas introduction passage 30 at the same time. It is like that.

  In the state shown in FIG. 2, the first branch exhaust passage 7 a is connected to the exhaust passage 5 by the inlet side switching valve 12, and the second branch exhaust passage 7 b is shut off from the exhaust passage 5. The first branch exhaust pipe 7a is connected to the atmosphere opening passage 9 and the second branch exhaust passage 7b is connected to the regenerative gas introduction passage 30. 10 is in a normal operation state, and the second branch exhaust pipe 7b is in a regeneration operation state by operating the adsorbed substance desorbing means 10.

(Operation of the first embodiment)
When the internal combustion engine 1 is operated in the state of FIG. 2, the basic operation is the same as in the case of the first embodiment and will be redundantly described. However, in the first branch exhaust passage 7 a in the normal operation state, NOx in the exhaust gas flowing in from the exhaust passage 5 is adsorbed by the NOx adsorbent 11, and CO and HC are oxidized and made harmless by the catalyst contained in the NOx adsorbent 11, and are exhausted from the atmosphere opening passage 9. .

  On the other hand, in the second branch exhaust passage 7b in the regeneration operation state, the adsorbed substance desorbing means 10 is operated, and the NOx adsorbent is burned with the air from the fuel nozzle 21 by the air from the air supply means 22. The high-temperature exhaust gas is supplied to 11 and the adsorbed NOx is desorbed from the NOx adsorbent 11, and a part thereof is reduced and removed by the catalyst contained in the NOx adsorbent 11 as in the first embodiment. The remainder flows from the junction 8 through the regeneration gas introduction passage 30 into the intake passage 3 and is mixed with intake air and introduced into the cylinder of the internal combustion engine 1. The NOx introduced into the cylinder is reduced in a combustion rich region in the combustion in the cylinder.

  The second branch exhaust passage 7b in the regeneration operation state is in a state in which the exhaust gas from the internal combustion engine 1 is shut off and is operated independently from the first branch exhaust passage 7a in the normal operation state. Since the regeneration operation is performed by the fuel supply and air supply from the separation unit 10, the amount of adsorbed material desorption air can be set regardless of the amount of exhaust gas from the internal combustion engine 1. The fuel supply amount can be saved. The flow rate of air supplied from the air supply means 22 during the regeneration operation is suppressed to 20% or less, preferably 10% or less of the exhaust gas of the internal combustion engine. As a result, the amount of fuel from the combustion nozzle 21 can be reduced, which is economical.

  When the NOx adsorption amount of the NOx adsorbent 11 reaches a predetermined amount (for example, a saturation amount) in the first branch exhaust passage 7a in the normal operation state, the inlet side switching valve 12 is switched to the second branch exhaust passage 7b side. Then, the adsorbed substance desorbing means 10 in the second branch exhaust passage 7b is stopped, and at the same time, the adsorbed substance desorbing means 10 in the first branch exhaust path 7a is activated. That is, the first branch exhaust passage 7a is set in the regeneration operation state, and at the same time, the second branch exhaust passage 7b is set in the normal operation state.

[ Second Embodiment of Exhaust Gas Purifying Apparatus for Implementing Control Method According to Present Invention and Control Method Thereof]
FIG. 3 shows a second embodiment, which is based on the exhaust gas purification device shown in FIG. 2. In addition to this basic configuration, each branch exhaust passage 7a, 7b has an adsorbed substance desorbing means (combustion device). ) A particulate filter 40 is disposed between 10 and the NOx adsorbent 11. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions.

  The operation is basically the same as in the case of FIG. 2 except that the particulate filter 40 is disposed upstream of the NOx adsorbent 11 so that the particulate filter can be used during normal operation (when used as an exhaust gas flow path). The exhaust gas from which the particulate matter has been removed at 40 can be caused to flow into the NOx adsorbent 11, and a reduction in the NOx adsorption rate by the NOx adsorbent 4 can be prevented.

  In normal operation, when the adsorption amount of the particulate matter becomes saturated and the back pressure increases, or when the NOx adsorption amount reaches a predetermined amount (for example, the saturation amount), the regeneration operation is switched to, and the adsorbed substance desorbing means 10 The particulate matter is incinerated and removed by combustion, and the particulate filter 40 is regenerated. At the same time, NOx of the NOx adsorbent 11 is desorbed and the NOx adsorbent 11 is regenerated.

  The particulate filter 40 may have a function of only capturing particulate matter, but may include a catalyst having an oxidizing action and a function of continuously oxidizing particulate matter.

[ Third embodiment of an exhaust gas purifying apparatus for performing the control method according to the present invention and its control method]
FIG. 4 shows a third embodiment, which is based on the exhaust gas purifying apparatus shown in FIG. 2. In addition to this basic configuration, a fine filter 40 similar to that in FIG. 3 is provided in the branch exhaust passages 7a and 7b. In addition, an SOx adsorbent 42 is disposed. The SOx adsorbent 42 is disposed on the exhaust upstream side of the NOx adsorbent 11, and the particulate filter 40 is further disposed on the exhaust upstream side of the SOx adsorbent 42. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions. Even if the SOx adsorbent 42 is disposed on the upstream side of the particulate filter 40, it operates without any problem. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions.

  The action is basically the same as in the case of FIG. 3, but by arranging the SOx adsorbent 42 different from the NOx adsorbent 11, NOx and SOx are adsorbed efficiently during normal operation, A decrease in the adsorption rate of NOx by the NOx adsorbent 11 can be prevented.

[ Fourth embodiment of an exhaust gas purifying apparatus for performing a control method according to the present invention and its control method]
FIG. 5 shows a fourth embodiment, which is based on the exhaust gas purification device shown in FIG. 2 and is applied to the internal combustion engine 1 provided with a supercharger 45 in addition to this basic configuration. The turbocharger 45 has a turbine portion 45 a disposed in the middle of the exhaust passage 5 and a compression portion 45 b disposed in the intake passage 3. A compressed air take-out passage 46 is connected to the intake passage 3 portion on the intake air downstream side (pressurization side) with respect to the compressor 45b, and the compressed air take-out passage 46 is connected to the air metering device 16, thereby It saves a spare air supply. Other structures are the same as those of the second embodiment of FIG. 2, and the same components are denoted by the same reference numerals.

  According to this embodiment, since a part of the compressed air of the supercharger 50 is used for the air supply means 22 of the nitrogen oxide desorption means 10, a separate air supply source is provided as described above. It becomes unnecessary and the device can be miniaturized.

[ Fifth Embodiment of Exhaust Gas Purification Apparatus for Implementing Control Method According to Present Invention and Control Method Thereof]
FIG. 6 shows a fifth embodiment, which is based on the exhaust gas purification device shown in FIG. 2. In addition to this basic configuration, an oxidation catalyst 47 is arranged on the exhaust downstream side of the NOx adsorbent 11; It has become. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions.

  According to this embodiment, unburned components such as HC and CO discharged in a reducing atmosphere when NOx is released can be effectively oxidized and removed by the oxidation catalyst 47.

[ Sixth Embodiment of Exhaust Gas Purifying Apparatus for Implementing Control Method According to Present Invention and Control Method Thereof]
Figure 7 is a sixth embodiment of the present invention, has a basic exhaust gas purifying apparatus shown in FIG. 2, in addition to this basic configuration, an exhaust passage 5 of the exhaust upstream side of the adsorbed material detachment unit 10 An exhaust gas cooling means 50 is disposed therein, a temperature sensor 51 is disposed downstream of the exhaust gas cooling means 50, and the exhaust gas cooling means 50 and the temperature sensor 51 are connected to the ECU 25, and the exhaust gas The temperature of the exhaust gas coming out of the cooling means 50 can be set to a desired temperature. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions.

  According to this embodiment, during normal operation, the temperature of the exhaust gas flowing into the NOx adsorbent 11 can be adjusted to a temperature at which the adsorption capability of the NOx adsorbent 11 can be effectively exhibited, thereby purifying the exhaust gas. Function can be improved.

[ Seventh embodiment of an exhaust gas purifying apparatus for performing the control method according to the present invention and its control method]
FIG. 8 shows a seventh embodiment, which is based on the exhaust gas purification device shown in FIG. 2. In addition to this basic configuration, the inside of the regeneration gas introduction passage 30 between the outlet side switching valve 31 and the intake passage 3 is shown. In addition, a regenerative gas cooling means (heat exchanger) 53 is provided. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions.

  The gas regenerated from the NOx adsorbent 11 has a high temperature, and if mixed with the intake air at a high temperature, the temperature of the intake air may rise and affect the emission and fuel consumption. However, as in this embodiment, By cooling the regeneration gas by the regeneration gas cooling means 53 and mixing it with the intake air, the influence can be eliminated.

[Eighth embodiment and its control method of the exhaust gas purifying apparatus for carrying out the control method according to the present invention]
FIG. 9 shows an eighth embodiment, which is based on the exhaust gas purification device shown in FIG. 2. In addition to this basic configuration, the regeneration gas introduction passage 30 is provided between the outlet side switching valve 31 and the intake passage 3. Inside, a desulfurization apparatus 55 is disposed. As the desulfurization device 55, there are a method of absorbing and removing with an absorbing solution and an absorbent, and a method of adsorbing with activated carbon, SOx adsorbent and the like. The other structure is the same as that of FIG. 2, and the same reference numerals are given to the same parts and portions.

  In the case of using a fuel containing a sulfur component, the gas obtained by regenerating the NOx adsorbent 11 contains high-concentration sulfur oxide, but the outlet side switching valve 31 and the intake passage 3 of the internal combustion engine 1 are used. If the desulfurization device 55 is provided in the regeneration gas introduction passage 30 in the meantime, the high-concentration sulfur oxide can be removed before flowing into the internal combustion engine 1, preventing poisoning in the internal combustion engine 1, Durability can be maintained.

[Second reference example of exhaust gas purification device]
FIG. 10 shows a second reference example, which is based on the exhaust gas purifying apparatus having only the atmosphere opening passage 9 shown in FIG. 1, and in addition to this basic configuration, sensors for measuring temperatures and pressures at various places are arranged. In this configuration, appropriate control can be performed. Other structures are the same as those in FIG. 1, and the same parts and portions are denoted by the same reference numerals.

  In this example, an adsorption amount estimation sensor 60 is disposed on the downstream side of the NOx adsorbent 11, and a pressure sensor 61 and a temperature sensor 62 are disposed on the upstream side of the NOx adsorbent 11. Each sensor 60, 61, 62 is connected to the ECU 25, and each measured value is input to the ECU 25.

  The basic operation is the same as that described in the first embodiment, and a detailed description thereof is omitted.

  As shown in FIG. 10, during the normal operation of the first branch exhaust passage 7a, the NOx adsorption amount by the NOx adsorbent 11 in the first branch exhaust passage 7a is measured by the adsorption amount detection sensor 60, and is predetermined (for example, saturated). When the adsorbed amount reaches the first branch exhaust passage 7a, the inlet side switching valve 12 is switched to the second branch exhaust passage 7b side according to a command from the ECU 25, and the adsorbed substance desorbing means 10 in the first branch exhaust passage 7a is operated. The one branch exhaust passage 7a is set in the regeneration operation state. In parallel with this, the exhaust gas from the internal combustion engine 1 flows into the second branch exhaust passage 7b, and a normal operation state is set. When the first branch exhaust passage 7a is in a normal operation state, if the trapped amount of particulate matter in the NOx adsorbent 11 is saturated before the NOx adsorption amount, the pressure detection sensor 61 detects saturation of particulate matter, and switches the inlet side switching valve 12 to the second branch exhaust passage 7b side. Thereby, the fall of NOx adsorption performance by the pressure fall can be prevented.

[ Ninth embodiment of exhaust gas purifying apparatus for carrying out control method according to present invention and control method therefor]
FIG. 11 shows the ninth embodiment, which is based on the exhaust gas purifying apparatus shown in FIG. 2. In addition to this basic configuration, the temperature at various places is the same as in the tenth embodiment of FIG. In addition, a sensor that measures pressure and pressure is arranged to enable appropriate control. The same parts as those in FIGS. 2 and 10 are denoted by the same reference numerals. The operation and control are the same as in the case of FIG.

  FIG. 12 shows the time course of the control of the exhaust gas purifying apparatus A of FIG. 11. One of the first branch exhaust passage 7a and the second branch exhaust passage 7b is used for normal operation to adsorb NOx. While the other, the other shows that the regeneration operation is performed. The relationship shown in FIG. 12 is also applied to the exhaust gas purifying apparatus shown in FIGS.

[ Other embodiments ]
(1) As the NOx adsorbent 11, it is also possible to use a NOx adsorbent that uses a NOx adsorbent on the wall of the particulate filter.

(2) As the adsorbed substance desorbing means 10, for example, a temperature raising means for raising the temperature of the exhaust gas to a predetermined temperature or higher, or means for bringing the exhaust gas into a reducing atmosphere can be used. In addition, a reducing agent supply means may be added to the temperature raising means so that NOx and SOx can be adsorbed and desorbed efficiently. As the temperature raising means, for example, a heating resistor such as an electric heater can be used, whereby the temperature can be raised quickly and reliably. Further, as another example of the adsorbed substance desorbing means 10, it is possible to provide a fuel supply means. In this case, the supplied fuel serves as a reducing agent, and the oxidation contained in the NOx adsorbent 11. NOx is desorbed by utilizing the heat generated when it is oxidized on the catalyst having an action.

(3) It is also possible to apply to a structure branched into three or more branch exhaust passages. In this case, it is possible to regenerate the remaining branch exhaust passage while one branch exhaust passage is connected to the exhaust passage and used for normal operation. It is also possible to connect all remaining branch exhaust passages to the exhaust passage during the regeneration operation.

  The present invention is used as an exhaust gas purifying device for various internal combustion engines such as a diesel engine, a gas engine, a gasoline engine, or a gas turbine engine, but particularly in an exhaust gas such as an internal combustion engine operated by lean combustion. It is suitable for an internal combustion engine containing a large amount of NOx.

It is the schematic which shows the 1st reference example of an exhaust-gas purification apparatus . It is the schematic which shows 1st Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 2nd Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 3rd Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 4th Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 5th Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 6th Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 7th Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows 8th Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is the schematic which shows the 2nd reference example of an exhaust-gas purification apparatus . It is the schematic which shows 9th Embodiment of the exhaust-gas purification apparatus which implements the control method by this invention . It is a figure which shows the time relationship of the operation state of each branch exhaust passage in FIGS.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake manifold 3 Intake passage 4 Exhaust manifold 5 Exhaust passage 6 Branch part 8 Merge part 9 Atmospheric release path 10 Nitrogen oxide desorption means (combustion device)
11 Nitrogen oxide adsorbent (NOx adsorbent)
12 Inlet side switching valve (Inlet side switching means)
DESCRIPTION OF SYMBOLS 15 Fuel metering device 16 Air metering device 17 Air supply source 18 Fuel tank 21 Fuel nozzle (fuel supply means)
22 Air supply means 23 Ignition means 25 ECU
30 Regenerative gas introduction passage 31 Outlet side switching valve (outlet side switching means)
40 particulate filter 42 SOx adsorbent 45 supercharger 45a turbine section 45b compression section 50 exhaust gas cooling means 51 temperature sensor (temperature detection means)
53 Regenerative gas cooling means (heat exchanger)
55 Desulfurization device 60 Adsorption amount estimation sensor 61 Pressure sensor 61
62 Temperature sensor

Claims (5)

Branching the exhaust passage of the internal combustion engine into a plurality of branch exhaust passages via a branch portion;
The branch portion is provided with an inlet side switching valve that connects the exhaust passage to each branch exhaust passage in a switchable manner,
Each branch exhaust passage is provided with a nitrogen oxide adsorbent that temporarily adsorbs nitrogen oxides in an excess air atmosphere and desorbs the adsorbed nitrogen oxides in a temperature rising or reducing atmosphere. Provided on the upstream side of the exhaust of the material adsorbing material is an adsorbing substance desorbing means having an air supply means for raising the temperature of the air supplied from the air supply means or reducing atmosphere
The adsorbed substance desorbing means is composed of the air supply means, fuel supply means and ignition means,
Each of the branch exhaust passages joins at a joining portion on the downstream side of the nitrogen oxide adsorbent,
In the method for controlling the exhaust gas purification device , wherein the regeneration gas introduction passage connected to the intake passage of the internal combustion engine and the atmosphere release passage are connected to the merging portion by an outlet side switching valve .
A temperature detecting means is provided on the exhaust upstream side of the nitrogen oxide adsorbent provided in each branch exhaust passage,
An adsorption amount detection means for detecting the adsorption amount by the nitrogen oxide adsorbent is arranged on the exhaust gas downstream side of the nitrogen oxide adsorbent,
In the normal operation state, when the exhaust gas from the internal combustion engine flows into at least one branch exhaust passage, the amount of adsorption by the nitrogen oxide adsorbent is detected by the adsorption amount detection means, and when the amount of adsorption reaches a predetermined amount The exhaust gas flow into the branch exhaust passage is shut off by switching the inlet side switching valve, and the regeneration operation is performed by operating the air supply means and the adsorbed substance desorbing means. The regenerative gas containing the desorbed substance is controlled to be a reducing atmosphere and flows into the cylinder of the internal combustion engine through the regenerative gas introduction passage and the intake passage by switching the outlet side switching valve, and the adsorption amount detection When detecting the state where all the adsorbed substances of the nitrogen oxide adsorbing material are desorbed by the means, the operation of the adsorbing substance desorbing means is stopped, and the inlet side switching valve is switched to connect to the exhaust passage And control so as to return to a normal operating state,
A control method for an exhaust gas purifying apparatus, wherein all the branch exhaust passages are not subjected to the regeneration operation at the same time. In the control method of the exhaust-gas purification apparatus of Claim 1,
The method for controlling an exhaust gas purification apparatus, wherein the adsorbed substance desorbing means has an air flow rate supplied from the air supply means of 20% or less of an exhaust gas flow rate of an internal combustion engine . In the control method of the exhaust-gas purification apparatus of Claim 1,
Said combustion device, the combustion conditions to produce a reducing atmosphere for desorbing the adsorbed NOx is control of the exhaust gas purifying device which is a range in excess air ratio 0.4 to 0.9 Method. In the control method of the exhaust-gas purification apparatus of Claim 1,
It said air supply means, the exhaust gas exhaust passage connected to the outlet portion of the compression section of the supercharger of an internal combustion engine to be connected, characterized in that you have to make use of the compressed air discharged from the compressor unit Control method of purification device . In the control method of the exhaust-gas purification apparatus of Claim 1,
An exhaust gas cooling means is disposed upstream of the adsorbed substance desorbing means, and a temperature sensor is provided for measuring the temperature of the exhaust gas coming out of the exhaust gas cooling means. A control method for an exhaust gas purifying apparatus, wherein the exhaust gas temperature can be arbitrarily set.

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