JP6179258B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine for purifying nitrogen oxides contained in exhaust gas from the internal combustion engine.

  Conventionally, a technique for purifying nitrogen oxide (NOx) contained in exhaust gas has been proposed.

For example, Patent Document 1 includes a dry process for generating atmospheric low-temperature non-equilibrium plasma in exhaust gas, and the generation of low-temperature non-equilibrium plasma results in oxidation of NO in the gas and a maximum value of NO _2. An applied voltage is set as a reference, and after the NO contained in the gas is efficiently oxidized to NO ₂ , a wet process for reacting the exhaust gas with the reducing agent solution is provided, and nitrogen oxide / sulfur oxide in the exhaust gas is provided. A purification device for removing water is disclosed.

For example, in Patent Document 2, in an exhaust gas treatment apparatus including an adsorption tower having an adsorption layer filled with an adsorbent, an adsorption process for adsorbing NOx contained in exhaust gas discharged from an engine, and thermal energy of the exhaust gas are used. Switching between a desorption process in which the adsorbent in the adsorption tower is heated to desorb NOx from the adsorbent and the desorption gas is reduced to N ₂ by plasma treatment, and a cooling process in which the adsorbent heated in the desorption process is cooled. Techniques to be performed are disclosed.

Japanese Patent Application Laid-Open No. 2000-117049 International Publication No. 2009/031454 Pamphlet

  However, in the method described in Patent Document 1, it is necessary to replenish the reducing agent solution as needed in order to continuously treat the exhaust gas. Therefore, there exists a subject that the effort for maintaining and managing an exhaust gas treatment function is large.

  Further, in the method described in Patent Document 2, in order to simultaneously purify NOx while absorbing NOx, it is necessary to have two adsorption layers, which not only increases the size of the apparatus but also complicates the control. There are challenges.

  Accordingly, an object of the present invention is to more efficiently reduce NOx discharged from an internal combustion engine in an exhaust gas purification apparatus for an internal combustion engine.

According to one aspect of the present invention, the occlusion medium you stores NOx, and storage means for storing NOx contained in the exhaust of an internal combustion engine to the storage medium, wherein the occluded in the occluding medium NOx combustion Supply means for supplying to the combustion chamber of the engine, detection means for detecting the amount of NOx stored in the storage medium, rotation speed torque detection means for detecting the rotation speed and torque of the internal combustion engine, and the storage medium The internal combustion engine has a NOx amount stored in the combustion chamber exceeding a predetermined value , and the internal combustion engine is determined from the NOx amount supplied to the combustion chamber based on the NOx amount supplied to the combustion chamber, the rotational speed and torque of the internal combustion engine. Control for obtaining a purification rate indicating a difference obtained by subtracting the amount of NOx to be discharged, and controlling the supply means to supply NOx stored in the storage medium to the combustion chamber when the purification rate is 0% or more Means and An exhaust purifying apparatus for obtaining an internal combustion engine.

  The invention according to claim 2 is the exhaust gas purification apparatus for an internal combustion engine according to claim 1, further comprising reforming means for reforming NOx contained in the exhaust gas of the internal combustion engine into nitric acid, The occlusion means is an exhaust gas purification apparatus for an internal combustion engine, wherein the nitric acid is occluded in the occlusion medium.

  An invention according to claim 3 is the exhaust gas purification apparatus for an internal combustion engine according to claim 2, wherein the reforming means adds an oxidant to the exhaust gas of the internal combustion engine. This is an exhaust purification device.

  According to a fourth aspect of the present invention, there is provided an exhaust purification apparatus for an internal combustion engine according to the second aspect, wherein the reforming means adds an oxidant to the storage medium. It is a purification device.

  A fifth aspect of the present invention is the exhaust gas purification apparatus for an internal combustion engine according to the first aspect, wherein the storage medium is water or an aqueous solution.

  The invention according to claim 6 is the exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the NOx occluded in the occlusion medium exists as nitric acid or nitrate ions. This is an exhaust purification device.

  The invention according to claim 7 is the exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the storage means for storing the storage medium, and the storage medium is circulated between the storage means and the storage means. An exhaust purification device for an internal combustion engine, further comprising a circulating means for causing the internal combustion engine to circulate.

  ADVANTAGE OF THE INVENTION According to this invention, in the exhaust gas purification apparatus of an internal combustion engine, NOx which an internal combustion engine exhausts can be reduced more efficiently.

It is a figure showing a schematic structure of an exhaust-air-purification device of an internal-combustion engine concerning a 1st embodiment. It is a flowchart which shows the flow of a process of the exhaust gas purification apparatus in 1st Embodiment. It is a figure which shows schematic structure of the exhaust gas purification apparatus of the internal combustion engine which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the exhaust gas purification apparatus in 3rd Embodiment. It is a figure which shows the example of a purification rate map. It is a figure which shows the other example of a purification rate map. 2 is a diagram showing a relationship between a NOx supply amount and a purification rate with respect to a predetermined rotation speed and torque of the engine 10. FIG. It is a flowchart which shows the flow of a process of the exhaust gas purification apparatus in 4th Embodiment. It is a figure which shows the structure (in-cylinder addition) of embodiment. It is a figure which shows the modification of the structure (in-cylinder addition) of embodiment. It is a figure which shows the structural example of NOx addition of embodiment. It is a flowchart which shows the procedure of the process of embodiment. It is a figure which shows the structure (intake valve vicinity addition) of embodiment. It is a figure which shows the structural example for interlocking | linkage with an intake valve. It is a figure which shows the other example of a structure for the interlocking | linkage with an intake valve. It is a figure which shows the further another example of the structure for interlocking | linkage with an intake valve. It is a figure which shows the structure (intake pipe addition) of embodiment. It is a figure which shows the structure (EGR pipe addition) of embodiment. It is a figure which shows the structure (4 addition place addition) of embodiment. It is a figure which shows the priority of 4 addition place. It is a flowchart which shows the procedure of the addition process of 4 addition places. It is a figure which shows a basic composition. It is a figure which shows the structure (NOx converter separate installation) of embodiment. It is a figure which shows the structure (installation in NOx converter EGR pipe | tube) of embodiment. It is a figure which shows the structure (installation in a NOx conversion device intake pipe) of embodiment. It is a figure which shows the structure (multiple location addition) of embodiment. It is a figure which shows the structural example (pipe wall) of NOx converter installation in piping. It is a figure which shows the structural example (filling in a pipe | tube) of installation in NOx converter piping. It is a figure which shows the example using an intake valve. It is a figure which shows the example using an addition valve.

<First Embodiment>
Hereinafter, an example of an embodiment of an exhaust emission control device for an internal combustion engine according to the present invention will be described. FIG. 1 is a diagram illustrating an example of a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to the first embodiment.

  The exhaust gas purification apparatus for an internal combustion engine according to the present embodiment includes an engine 10, an exhaust pipe 12, a turbocharger 14, an intake pipe 16, an intercooler 18, a NOx collection device 20, a storage medium 22, a NOx storage tank 24, a circulation pump 26, The ECU 42 includes an EGR pipe 28, an EGR cooler 30, a NOx sensor 32, a rotation speed / torque sensor 34, a NOx supply pipe 36, a NOx supply pump 38, an addition valve 40, and an ECU 42 having a storage means 44.

  The engine 10 is an internal combustion engine and generates power by burning fuel in a cylinder. The engine 10 is a spark ignition engine such as a gasoline engine. Alternatively, it may be a compression ignition engine such as a diesel engine.

The exhaust pipe 12 is connected to the exhaust side of the engine 10 and serves as a passage for exhaust gas discharged from the engine 10. The exhaust gas discharged from the engine 10 into the exhaust pipe 12 contains NOx (nitrogen oxide), which is a harmful component, generated by the combustion of fuel in the engine. NOx is, for example, NO (nitrogen monoxide), NO ₂ (nitrogen dioxide), N ₂ O (zincated nitrogen), N ₂ O ₅ (dinitrogen pentoxide), N2O3 (dinitrogen trioxide), N2O4 (four) Dinitrogen oxide), HNO3 (nitric acid), NO3 (nitric acid ion), HNO2 (nitrous acid), and the like.

  The turbocharger 14 is provided in the exhaust pipe 12. The turbocharger 14 uses the exhaust gas that has passed through the exhaust pipe 12 to rotate the turbine included therein at a high speed, and drives the centrifugal compressor included therein by the rotational force, thereby compressing the compressed air into the engine 10. To send.

  The intake pipe 16 connects the turbocharger 14 and the intake side of the engine 10. The intake pipe 16 serves as a passage for air compressed by the turbocharger 14.

  The intercooler 18 is provided in the intake pipe 16. The intercooler 18 cools the air compressed by the turbocharger 14 and increases the intake mass per unit volume of the engine 10.

The NOx collection device 20 is provided in the exhaust pipe 12. The NOx trap 20 stores NOx in the exhaust gas of the engine 10 in the storage medium 22 and separates NOx from the exhaust gas. As the NOx collection device 20, for example, an exhaust passage and an occlusion medium are separated by a porous film, and NOx contained in the exhaust gas is absorbed from the exhaust passage through the porous film by contacting the occlusion medium and absorbing. A contact device can be used. Alternatively, it is possible to use a scrubber that removes NOx by making countercurrent contact with the shower-like storage medium 22. One example of the storage medium 22 is water, but a medium that can be used as the storage medium 22 is not limited thereto. For example, an aqueous solution in which alkaline salts such as potassium carbonate and sodium carbonate, alkaline earth salts such as calcium carbonate and magnesium carbonate, ammonium salts such as ammonium carbonate and ammonium hydrogen carbonate, and the like are dissolved may be used. Alternatively, ionic liquid, anhydrous alcohol, gasoline or the like may be used. When water is used for the storage medium 22, NOx is stored in the storage medium 22 as nitric acid (HNO ₃ ) or nitrate ions (NO ₃ −).

  The NOx storage tank 24 is provided for storing the storage medium 22 including the storage medium 22 storing NOx, and is connected to the NOx collection device 20. The NOx storage tank 24 includes a circulation pump 26.

  The circulation pump 26 pumps the storage medium 22 from the NOx storage tank 24 and supplies it to the NOx trap 20. The storage medium 22 that has stored NOx in the NOx collection device 20 is returned to the NOx storage tank 24. Thus, the storage medium 22 circulates between the NOx collection device 20 and the NOx storage tank 24.

  The EGR pipe 28 is an exhaust gas recirculation pipe and connects the intake side and the exhaust side of the engine 10. Part of the exhaust gas from the engine 10 is returned to the intake side via the EGR pipe 28. This has the effect of reducing the combustion temperature in the combustion chamber of the engine 10 and reducing the amount of NOx generated.

  The EGR cooler 30 is provided in the EGR pipe 28. The EGR cooler 30 cools the exhaust gas of the engine 10 returned to the intake side of the engine 10.

The NOx sensor 32 is provided in the NOx storage tank 24 and detects the amount of NOx stored by the storage medium 22. For example, when water is used as the storage medium, the NOx sensor 32 is a NO ₃ measurement sensor or a pH measurement sensor that detects the amount of nitrate ions in the water.

  The rotational speed / torque sensor 34 is provided in the engine 10 and detects the rotational speed and torque of the engine 10. A sensor that detects the rotational speed of the engine 10 is, for example, a crank angle sensor. The sensor that detects the torque of the engine 10 is, for example, a magnetostrictive torque sensor.

  One end of the NOx supply pipe 36 is connected to the NOx storage tank 24. The NOx supply pipe 36 is branched, and the other ends are connected to the engine 10, the intake pipe 16, and the EGR pipe 28, respectively.

  The NOx supply pump 38 is provided in the NOx supply pipe 36. The NOx supply pump 38 pumps the storage medium 22 from the NOx storage tank 24 and supplies the storage medium 22 to the NOx supply pipe 36.

  The addition valve 40 is provided in the NOx supply pipe 36. The addition valve 40 is provided in the vicinity of the engine 10, the intake pipe 16, and the EGR pipe 28, respectively. The addition valve 40 controls the flow of the storage medium 22 in the NOx supply pipe 36 by opening and closing. The NOx supply pipe 36, the NOx supply pump 38, and the addition valve 40 serve as supply means for supplying NOx stored in the storage medium to the combustion chamber of the engine 10.

  The ECU 42 is an electronic control unit including a CPU, storage means 44, and the like, and performs electronic control of the engine 10 and other devices. The ECU 42 performs pressure control of the NOx supply pump 38 and opening / closing control of the addition valve 40 to control the amount of NOx supplied to the combustion chamber of the engine 10. Further, the ECU 42 receives values detected from the NOx sensor 32 and the rotation speed / torque sensor 34 and performs calculations based on these values.

  The storage unit 44 is, for example, a RAM or a ROM, and is provided so as to be accessible from the ECU 42. The storage means 44 stores the values detected from the NOx sensor 32 and the rotation speed / torque sensor 34 received by the ECU 42. The storage unit 44 stores a purification rate map, which will be described later.

  Hereinafter, the operation of the exhaust gas purification apparatus for an internal combustion engine according to the first embodiment will be described. FIG. 2 is a flowchart showing the flow of processing of the exhaust emission control device in the first embodiment.

  In step S <b> 10, the ECU 42 acquires the NOx storage amount of the storage medium 22 stored in the NOx storage tank 24. Specifically, the ECU 42 acquires the amount of NOx stored in the storage medium 22 by receiving the value detected by the NOx sensor 32. The ECU 42 stores the acquired value of the stored amount of NOx in the storage unit 44.

  In step S12, the ECU 42 determines whether or not the acquired NOx storage amount of the storage medium 22 is equal to or greater than a predetermined value. When the NOx storage amount of the storage medium 22 is greater than or equal to the predetermined value (“Yes” in step S102), the process proceeds to step S14. If the NOx storage amount of the storage medium 22 is not equal to or greater than the predetermined value (“No” in step S102), the process ends without performing any processing. As will be described later, as the amount of NOx occluded in the occlusion medium 22 increases, NOx can be efficiently reduced. Therefore, in the present embodiment, the process of supplying the NOx occluded in the occlusion medium 22 to the combustion chamber of the engine 10 is performed only when the amount of NOx occluded in the occlusion medium 22 is greater than or equal to a predetermined value. .

  In step S <b> 14, the ECU 42 supplies NOx stored in the storage medium 22 to the combustion chamber of the engine 10. Specifically, the storage medium 22 is pumped up by the pressure preset by the ECU 42 to the NOx supply pump 38, and the addition valve 40 is opened for a preset time by the ECU 42. In the present embodiment, three addition valves 40 are provided, but NOx occluded in the occlusion medium 22 from any of the addition valves 40 may be supplied. For example, it may be supplied directly to the combustion chamber of the engine 10 according to the operating state of the engine, discharged into the EGR pipe 28 and supplied to the combustion chamber via the EGR pipe 28, or Alternatively, it may be discharged into the intake pipe 16 and supplied to the combustion chamber via the intake pipe 16.

In the present embodiment, the amount of NOx discharged from the engine 10 is reduced by supplying NOx to the combustion chamber of the engine 10. NOx is generated when nitrogen (N) contained in the fuel or nitrogen (N) in the air is oxidized during high temperature combustion. This chemical reaction is an equilibrium reaction, and NOx is generated based on the Zeldovic mechanism. The Zeldovic mechanism is represented by the following chemical reaction formula.
N ₂ + O⇔NO + N
O ₂ + N⇔NO + O
N + OH⇔NO + H
Here, paying attention to the fact that NOx is generated by an equilibrium reaction, by supplying a predetermined amount of NOx into the combustion chamber during combustion of the fuel, the generation of NOx during combustion is suppressed, and at the same time, the supplied NOx is decomposed. Yes.

  In the present embodiment, water is used as the storage medium 22, and the water stored in the NOx is supplied to the combustion chamber of the engine 10, so the amount of water in the NOx storage tank 24 decreases. For this reason, the water content in the NOx storage tank 24 is kept above the specified value by collecting the moisture in the exhaust gas of the engine 10 and supplying it to the NOx storage tank 24. Alternatively, water may be replenished from the outside. The amount of the storage medium 22 in the NOx storage tank 24 is constantly monitored by a sensor or the like.

  As described above, in the present embodiment, NOx stored in the storage medium 22 is supplied to the combustion chamber of the engine 10. Thereby, compared with the past, it is possible to reduce the NOx emission amount of the engine 10 more efficiently. Further, NOx is occluded in the NOx collection device 20, and NOx is decomposed in the combustion chamber of the engine 10, that is, NOx is decomposed and occluded in separate devices, so that NOx is decomposed and occluded. It is possible to do at the same time.

Second Embodiment
Hereinafter, an exhaust emission control device for an internal combustion engine according to a second embodiment will be described. FIG. 3 is a diagram illustrating an example of a schematic configuration of the exhaust gas purification apparatus for an internal combustion engine according to the second embodiment. In the second embodiment, in addition to the configuration of the first embodiment, an oxidant generator 50, an oxidant supply valve 52, a reformer 54, and a NOx converter 56 are provided. The description of the same configuration as in the first embodiment is omitted.

  The oxidant generator 50 generates an oxidant. In the present embodiment, ozone is used as the oxidizing agent, but is not limited thereto. The oxidizing agent production | generation apparatus 50 produces | generates ozone by the electrolytic method, for example. The electrolytic method generates ozone by electrolyzing water.

  The oxidant supply valve 52 supplies the oxidant generated by the oxidant generator 50 to the reformer 54 by opening and closing. The oxidant supply valve 52 is controlled by the ECU 42.

  The reformer 54 is provided on the upstream side of the NOx collection device 20 in the exhaust pipe 12. The reformer 54 is a device that promotes the storage of NOx into the storage medium 22 and is a device that promotes the conversion of NOx to nitric acid. The reformer 54 includes a nitric acid generation catalyst, ozone is added by the oxidant supply valve 52, and the NOx and water vapor in the exhaust gas are reacted with ozone to generate nitric acid.

  The NOx conversion device 56 is provided in the NOx supply pipe 36 and decomposes nitric acid or nitrate ions contained in the storage medium 22 into NOx. The NOx decomposed by the NOx conversion device 56 is supplied from the NOx conversion device 56 to the combustion chamber of the engine 10 by the addition valve 40 via the NOx supply pipe 36. The storage medium 22 in which NOx is decomposed may be returned to the NOx storage tank 24.

  When NOx in the exhaust gas discharged from the engine 10 is directly stored in the storage medium 22 such as water, the storage speed is slow and the NOx cannot be stored in the storage medium 22 efficiently. On the other hand, the occlusion rate of nitric acid with respect to water is higher than when NOx is occluded directly into water. Therefore, in the present embodiment, the NOx is converted into nitric acid in advance by the reformer 54 before the processing of the NOx trap 20. Thereby, it is possible to efficiently store NOx in the storage medium 22.

  In this embodiment, NOx is converted to nitric acid by supplying ozone generated by the oxidant generator 50 to the reformer 54, but NOx may be converted to nitric acid by other methods. . For example, the nitric acid generation reaction may be promoted by adding an oxidizing agent such as hydrogen peroxide to the storage medium 22.

<Third Embodiment>
The operation of the exhaust gas purification apparatus for an internal combustion engine according to the third embodiment will be described below. The configuration of the exhaust emission control device according to the third embodiment is the same as that of the first embodiment. FIG. 4 is a flowchart showing the flow of processing of the exhaust emission control device in the third embodiment.

  In step S <b> 100, the ECU 42 acquires the NOx storage amount of the storage medium 22 stored in the NOx storage tank 24. Specifically, the ECU 42 acquires the amount of NOx stored in the storage medium 22 by receiving the value detected by the NOx sensor 32. The ECU 42 stores the acquired value of the stored amount of NOx in the storage unit 44.

  In step S102, the ECU 42 determines whether or not the acquired NOx storage amount of the storage medium 22 is equal to or greater than a predetermined value. When the NOx storage amount of the storage medium 22 is equal to or greater than the predetermined value (“Yes” in step S102), the process proceeds to step S104. If the NOx storage amount of the storage medium 22 is not equal to or greater than the predetermined value (“No” in step S102), the process ends without performing any processing. As will be described later, as the amount of NOx occluded in the occlusion medium 22 increases, NOx can be efficiently reduced. Therefore, in the present embodiment, the process of supplying the NOx occluded in the occlusion medium 22 to the combustion chamber of the engine 10 is performed only when the amount of NOx occluded in the occlusion medium 22 is greater than or equal to a predetermined value. .

  In step S104, the ECU 42 acquires the rotational speed and torque of the engine 10. The rotation speed and torque are acquired by receiving values from the rotation speed / torque sensor 34. Alternatively, the ECU 42 may calculate the torque of the engine 10 by detecting the degree of depression of the accelerator pedal.

  In step S106, the ECU 42 sets the amount of NOx supplied to the combustion chamber of the engine 10. Specifically, the ECU 42 sets the amount of NOx supplied to the combustion chamber by setting the pressure of the NOx supply pump 38 and the opening / closing time of the addition valve 40.

  In step S108, the ECU 42 reads out a purification rate map corresponding to the NOx amount supplied to the combustion chamber set from the storage means 44.

Here, the purification rate and the purification rate map will be described. The purification rate is expressed by the following equation.

Purification rate = {(NOx supply amount−NOx emission amount) / (NOx supply amount)} × 100 (%)

As described above, the purification rate is a percentage of a value obtained by dividing the difference obtained by subtracting the NOx discharge amount from the NOx supply amount by the NOx supply amount. Here, the NOx supply amount is the amount of NOx supplied to the engine 10. The NOx emission amount is the NOx emission amount that the engine 10 exhausts due to the combustion of the cycle when NOx is supplied.

  FIG. 5 is a diagram illustrating an example of the purification rate map. The purification rate varies according to the NOx supply amount, the rotational speed of the engine 10 and the torque. The purification rate map is a map that shows how the purification rate varies according to changes in the rotational speed and torque of the engine 10 when the NOx supply amount is a predetermined value. That is, the purification rate map shows the correspondence relationship between the NOx amount supplied to the combustion chamber, the rotational speed and torque of the engine 10, and the purification rate. The purification rate map is created in advance by measuring the purification rate with respect to the rotation speed, torque, and NOx supply amount of the engine 10 and is stored in the storage means 44.

  The purification rate map shown in FIG. 5 is a purification rate map when the NOx supply amount is 2.5 (L / min) and NO (100%). The purification rate map shown in FIG. 5 indicates that the purification rate is about 25% when the rotational speed is 2000 (rpm) and the torque is 50 (Nm), for example. For example, when the rotational speed is 2500 (rpm) and the torque is 120 (Nm), the purification rate is less than 0%.

  FIG. 6 is a diagram illustrating another example of the purification rate map. The purification rate map shown in FIG. 6 is a purification rate map when the NOx supply amount is 1.0 (L / min) and NO (100%). The purification rate map shown in FIG. 6 indicates that the purification rate is about 0% when the rotational speed is 2500 (rpm) and the torque is 60 (Nm), for example.

  As shown in FIGS. 5 and 6, if the rotation speed and torque of the engine 10 are the same value, the purification rate tends to increase as the NOx supply amount increases. Therefore, it is possible to efficiently purify NOx as the supply amount of NOx increases.

  In step S110, the ECU 42 refers to the purification rate map read from the storage unit 44, and determines whether or not the obtained purification rate in the rotational speed and torque of the engine 10 is 0% or more. When the purification rate is 0% or more (“Yes” in step S110), the process proceeds to step S112. If the purification rate is less than 0% (“No” in step S110), the process ends without performing any processing.

  In step S <b> 112, the ECU 42 supplies NOx stored in the storage medium 22 to the combustion chamber of the engine 10. Specifically, the NOx supply pump 38 is caused to pump the storage medium 22 at the pressure set in step S106, and the addition valve 40 is opened for the time set in step S106. In the present embodiment, three addition valves 40 are provided, but NOx occluded in the occlusion medium 22 from any of the addition valves 40 may be supplied. For example, it may be supplied directly to the combustion chamber of the engine 10 according to the operating state of the engine, discharged into the EGR pipe 28 and supplied to the combustion chamber via the EGR pipe 28, or Alternatively, it may be discharged into the intake pipe 16 and supplied to the combustion chamber via the intake pipe 16.

  In this embodiment, the amount of NOx supplied to the combustion chamber is set in advance, and the timing of supplying NOx into the combustion chamber is controlled based on the purification rate map corresponding to the set NOx amount. Based on the rotational speed and torque, the amount of NOx supplied to the combustion chamber may be appropriately varied so that the purification rate becomes 0% or more.

  FIG. 7 is a diagram showing the relationship between the NOx supply amount and the purification rate with respect to a predetermined rotational speed and torque of the engine 10. FIG. 7A shows the relationship between the NOx supply amount to the combustion chamber of the engine 10 and the purification rate when the rotational speed of the engine 10 is 1500 (rpm) and the torque is 30 (Nm). FIG. 7B shows the relationship between the NOx supply amount to the combustion chamber of the engine 10 and the purification rate when the rotational speed of the engine 10 is 2000 (rpm) and the torque is 60 (Nm). Yes. If the rotation speed and torque of the engine 10 are the same value, the tendency that the purification rate becomes higher as the NOx supply amount increases can also be read from FIG.

  For example, when the amount of NOx supplied to the combustion chamber set by the ECU 42 is 0.5 (L / min), the rotational speed of the engine 10 is 2000 (rpm), and the torque is 60 (Nm), FIG. ), The purification rate is about -25%, that is, less than 0%. At this time, the ECU 42 may appropriately change the amount of NOx supplied to the combustion chamber so that the purification rate becomes 0% or more based on the correspondence shown in FIG. Specifically, the amount of NOx supplied to the combustion chamber is changed to, for example, 1.5 (L / min), and NOx in an amount of 1.5 (L / min) is supplied to the combustion chamber. As shown in FIG. 7B, the rotational speed of the engine 10 is 2000 (rpm), the torque is 60 (Nm), and the NOx supply amount is 1.5 (L / min) between 10 and 20%, that is, 0%. That's it.

  In the present embodiment, water is used as the storage medium 22, and the water stored in the NOx is supplied to the combustion chamber of the engine 10, so the amount of water in the NOx storage tank 24 decreases. For this reason, the water content in the NOx storage tank 24 is kept above the specified value by collecting the moisture in the exhaust gas of the engine 10 and supplying it to the NOx storage tank 24. Alternatively, water may be replenished from the outside. The amount of the storage medium 22 in the NOx storage tank 24 is constantly monitored by a sensor or the like.

  As described above, in the present embodiment, NOx stored in the storage medium 22 is supplied to the combustion chamber of the engine 10 only when the purification rate is 0% or more. Thereby, compared with the past, it is possible to reduce the NOx emission amount of the engine 10 more efficiently. Further, NOx is occluded in the NOx collection device 20, and NOx is decomposed in the combustion chamber of the engine 10, that is, NOx is decomposed and occluded in separate devices, so that NOx is decomposed and occluded. It is possible to do at the same time.

<Fourth embodiment>
The operation of the exhaust gas purification apparatus for an internal combustion engine according to the fourth embodiment will be described below. The configuration of the exhaust emission control device according to the fourth embodiment is the same as that of the first embodiment. FIG. 8 is a flowchart showing the flow of processing of the exhaust emission control device in the fourth embodiment. Steps S100 to S112 are the same as those in the third embodiment, and a description thereof will be omitted. In the present embodiment, when it is determined that the purification rate is less than 0% (“No” in Step S110), the process proceeds to Step S120, and processing different from that in the third embodiment is performed thereafter.

  In step S120, it is determined whether the NOx storage amount of the storage medium 22 is greater than or equal to the second value. If the NOx storage amount is greater than or equal to the second value (“Yes” in step S120), the process proceeds to step S122. If the NOx storage amount is less than the second value (“No” in step S120), the process ends without performing any processing. Here, the second value is a value larger than the first value, which is a threshold value for determining the NOx storage amount of the storage medium 22 in step S102. The second value is, for example, an amount that hinders the storage of NOx in the NOx collection device 20 when the NOx storage amount of the storage medium 22 is further increased.

  In step S122, the ECU 42 varies the rotation speed and torque so that the purification rate becomes 0% or more while keeping the output of the engine 10 constant. In FIG. 6, an iso-output line 100 is drawn. For example, when the rotational speed of the engine 10 is 1300 (rpm) and the torque is 80 (Nm), the ECU 42 varies the rotational speed and torque of the engine 10 along the iso-output line 100. For example, the rotational speed is 2000 (rpm) and the torque is 20 (Nm). Under the operating condition of the engine after the fluctuation, the purification rate is between 10% and 20%, that is, 0% or more.

  After the engine operating conditions are changed in step S122, the process proceeds to step S112, and the ECU 42 supplies the NOx stored in the storage medium 22 to the combustion chamber of the engine 10.

  In the flowchart shown in FIG. 8, when it is determined in step S110 that the purification rate is less than 0%, the NOx storage amount of the storage medium 22 is determined in step S120, but this determination is omitted. Also good. That is, when it is determined in step S110 that the purification rate is less than 0%, the process immediately proceeds to step S122, and the rotational speed and torque of the engine 10 may be changed so that the purification rate becomes 0% or more. .

  As described above, in the present embodiment, even if the purification rate is less than 0%, the rotational speed and torque of the engine 10 are varied while keeping the output of the engine 10 constant, so that the purification rate is 0% or more. After that, the NOx stored in the storage medium 22 is supplied to the combustion chamber of the engine 10. As a result, even when the engine is operating with a purification rate of less than 0%, the amount of NOx stored in the storage medium 22 is increased by a predetermined value or more, thereby preventing the NOx storage device 20 from interfering with NOx storage. Making it possible.

<Fifth Embodiment>
Hereinafter, a fifth embodiment will be described based on the drawings.

  In the exhaust gas purification apparatus for an internal combustion engine according to the present embodiment, as shown in FIG. 22, the NOx trapping device 2 that stores NOx in the exhaust gas of the internal combustion engine 1 in the storage medium and separates NOx from the exhaust gas, and NOx The NOx storage tank 3 for storing the occluded storage medium, the addition device 4 for adding the storage medium of the NOx storage tank via the intake system of the engine of the internal combustion engine or into the combustion cylinder of the internal combustion engine, and the addition device An addition field state detection device 5 that detects the state of the addition field to which the storage medium is added, and a controller 6 that controls the addition timing of the storage medium according to the detected state of the addition field. The storage medium for storing NOx is hereinafter referred to as a collection liquid.

"Overall configuration of the device"
FIG. 9 is a diagram illustrating a configuration of the embodiment. About the structure similar to the above-mentioned 1st-4th embodiment, the same number is attached | subjected and description is abbreviate | omitted.

  The cylinder 10a of the engine 10 is provided with an intake valve (not shown), and an intake pipe 16 is connected through the intake valve. An air filter 15 is attached to the tip of the intake pipe 16, and the air filtered here is supplied into the cylinder (cylinder) 10 a of the engine 10 through the turbocharger 14, the intercooler 18, and the intake valve 90. The turbocharger 14 increases the intake amount by exhaust, and the intercooler 18 cools the intake air to increase the intake amount.

  The cylinder 10a of the engine 10 is provided with an exhaust valve (not shown), and an exhaust pipe 12 is connected through the exhaust valve. The exhaust pipe 12 is connected to a NOx collection device 20 via a turbocharger 14. After NOx is removed here, exhaust gas is released. If it is necessary to remove other harmful emissions, a corresponding treatment device may be provided.

  The EGR pipe 28 is provided with an EGR valve 29 for controlling the timing and amount of exhaust gas circulation.

"In-cylinder addition"
Here, in the example shown in FIG. 9, the NOx supply pipe 36 is connected to a supply nozzle that supplies the collected liquid into the cylinder 10 a via the addition valve 40. Accordingly, by opening the addition valve 40 while the NOx supply pump 38 is driven, the collected liquid in the NOx storage tank 24 is supplied into the cylinder 10a. The timing and amount of supplying the collected liquid into the cylinder 10a are controlled by the ECU 42 as a controller.

  Further, if the collection timing of the collected liquid is poor, the collected liquid enters the intake / exhaust pipe and the EGR pipe, stops there, and the corrosion of the intake pipe and the EGR pipe easily proceeds. Therefore, it is necessary to prevent such a situation.

  In the present embodiment, the collected liquid is added directly into the cylinder 10a. In the case of a diesel engine, the collected liquid is injected simultaneously with the fuel injection in the compression process in the cylinder 10a or after ignition. As a result, the NOx concentration during combustion can be set to a desired value, and since the collected liquid is immediately vaporized, it is possible to prevent the liquid from adhering to the cylinder 10a. In a gasoline engine, the timing immediately after ignition or immediately after ignition is suitable. By adding the collected liquid at such timing, the collected liquid is vaporized immediately after the addition and does not adhere to the cylinder or the like, and also exists as NOx in the cylinder 10a in the same manner as the intake air during fuel combustion. it can.

  FIG. 10 shows a modification of the present embodiment. In this example, a NOx conversion device 56 and a NOx (gas) storage tank 58 are provided. FIG. 11 shows only the supply system for the collected liquid in this configuration.

  In this way, the collected liquid containing, for example, nitric acid in the NOx storage tank 24 is supplied to the NOx conversion device by the NOx supply pump 38, and the generated gaseous NOx is temporarily stored in the NOx (gas) storage tank 58. After being pressurized, it is added into the cylinder 10a through the addition valve 40. The timing of this addition is controlled by the ECU 42.

  The NOx conversion device 56 converts nitric acid into NOx gas, for example, by heat treatment. At this time, it is preferable to use a nitrate decomposition catalyst such as platinum. For thermal decomposition of nitric acids, it is preferable to heat to several hundred degrees C (about 200 to 500 degrees C), and for this purpose, it is preferable to use exhaust heat of the engine. Moreover, the higher the NOx concentration in the converted NOx gas, the better. Therefore, when the NOx concentration detected by the NOx sensor 32 is equal to or higher than a predetermined value, the collected liquid may be sent to the NOx conversion device 56.

  The NOx gas from the NOx conversion device 56 is stored in the NOx (gas) storage tank 58, and the pressure rises. The NOx (gas) storage tank 58 is provided with a pressure sensor 94 for detecting its internal pressure, and the cylinder 10a is provided with a pressure sensor 96 for measuring the pressure in the cylinder as an addition field state detection device. Yes. Based on the detected values of the pressure sensors 94 and 96, the ECU 42 applies the pressure into the cylinder 10a when the pressure in the cylinder 10a is lower than the pressure of NOx pressurized in the NOx (gas) storage tank 58. When it is determined that the addition is possible, and when it is determined that the operating state can sufficiently purify NOx by a signal from the ECU 42 that controls the operation of the engine 10, the addition is made into the cylinder 10a.

  As described above, in the case of a diesel engine, it is desirable to add sparks at the same time as fuel injection or after ignition. These timings are controlled by the injection / ignition timing control signals.

  In addition, since it changes also whether NOx reduces by combustion according to the rotation speed and output torque of the engine 10, this is also considered.

  Here, in FIG. 12, the flowchart of the collection liquid addition control by ECU42 in the structure of FIG.

  First, the NOx concentration in the collected liquid is measured by the NOx sensor 32 (S211), and the measured NOx concentration is compared with a set value (S212). The amount of NOx added is preferably 2.5 (L / min) or more.

  If the NOx concentration is equal to or greater than a predetermined value, the engine speed and output torque (these are always known in the vehicle) are taken in (S213), and whether the engine 10 is in an operation state where NOx can be purified from the operation state. Determination is made (S214). If it can be purified, the NOx supply pump 38 is operated to add the collected liquid to the NOx converter 56 (S215).

  The internal pressure of the cylinder 10a and the internal pressure (injection pressure) of the NOx (gas) storage tank 58 are compared (S216). If the injection pressure is higher, the injection valve is turned on in accordance with the timing of the combustion timing, NOx gas is added into the cylinder 10a (S217).

  In addition, when it is below the set value in S212 and cannot be purified in S214, and the injection pressure is lower in S216, the process ends without adding NOx.

  Thus, NOx can be purified, and NOx is added to the cylinder 10a at a timing at which there is no problem with the addition, so that reliable NOx processing can be performed. In the present embodiment, since NOx gas is added, there is little adverse effect on the cylinder.

"Addition to the intake pipe near the intake valve"
FIG. 13 shows an example in which NOx is added to the intake pipe 16 near the intake valve 60 of the cylinder 10a. Thus, the valve opening / closing detection device 80 that detects the opening / closing of the intake valve 60 detects the opening / closing state of the corresponding intake valve 60, and when the intake valve 60 is open, the addition valve 40 is opened and NOx is added. . In this example, a NOx conversion device 56 and a NOx (gas) storage tank 58 are provided, and gaseous NOx is added, but not limited to this, liquid NOx (nitric acid) may be added directly. .

  Here, in this embodiment, NOx is added to the intake pipe. However, if NOx is added when the intake valve 60 is closed, the intake pipe 16 and the EGR pipe 28 may be adversely affected. In particular, when liquid NOx is added, the adverse effect is large. Therefore, in the present embodiment, the valve opening / closing detection device 80 detects that the intake valve 60 is in an open state, and adjusts the NOx addition timing.

  FIG. 14 shows a configuration example in which opening / closing of the intake valve 60 and opening / closing of the addition valve are mechanically linked. The intake valve 60 is opened and closed by the upper bar 60 a of the intake valve 60 being moved up and down by the rotation of the cam 62. In the figure, the intake valve is pushed down by the cam 62 and opened. The upper bar 60a of the intake valve 60 is connected to an inverted V-shaped interlocking mechanism 64 in which a pair of bars are connected by a joint 64a and opened downward. One end of the upper bar of the interlocking mechanism 64 is rotatably fixed to the bar 60a of the intake valve 60, and the middle part of the upper bar is fixed with a pin, which serves as a fulcrum. Therefore, when the intake valve 60 moves upward, the joint 64a of the interlocking mechanism 64 moves downward. The tip of the lower bar of the interlocking mechanism 64 is connected to the addition valve 68, and the addition valve 68 is opened when the lower bar of the interlocking mechanism 64 moves downward. Since the NOx supply pipe 70 is connected to the addition valve 68, NOx gas is added into the intake pipe 16 when the addition valve 68 is opened.

  Thus, in the example of FIG. 14, the intake valve 60 and the addition valve 68 are mechanically connected, and the opening operation of the intake valve 60 and the opening operation of the addition valve 68 are interlocked. Therefore, the opening operation of the intake valve 60 can be detected and the addition valve 68 can be controlled to open automatically using a mechanical mechanism.

  FIG. 15 shows another configuration example for opening and closing the addition valve 68. In this example, the rotation position measuring device 72 measures the rotation of the cam 62 that drives the intake valve 60. The opening of the intake valve 60 is detected based on the detection result of the rotational position measuring device 72, and the injection control device 74 controls the addition valve. Also with this configuration, NOx can be supplied to the vicinity of the intake valve 60 in the intake pipe 16 in accordance with the opening of the intake valve 60.

  FIG. 16 shows still another configuration example for opening and closing the addition valve 68. In this example, the movement of the intake valve is detected by the valve opening / closing detection device 80. The valve opening / closing detection device 80 includes a permanent magnet 80a attached to the bar of the intake valve 60 and a coil 80b disposed around the permanent magnet 80a, and the movement of the permanent magnet 80a (opening of the intake valve 60). Is detected as a current flowing through the coil 80b. An injection control device 82 is connected to the valve opening / closing detection device 80, and when the intake valve 60 is in an open state, the injection control device 82 opens the addition valve 68 to control the addition of NOx.

  Thus, when adding NOx into the intake pipe 16 in the vicinity of the intake valve 60, the condition is that the intake valve 60 is open. Furthermore, when liquid NOx is added, it is preferable that the temperature in the vicinity of the intake valve 60 is equal to or higher than a predetermined value. That is, liquid NOx can be prevented from adhering to the intake pipe 16 and the intake valve 60.

"Addition to the intake pipe before the intercooler"
FIG. 17 shows a configuration in which NOx is added to the upstream side of the intercooler 18 of the intake pipe 16. An intake state in the intake pipe 16 on the downstream side of the turbocharger 14 and on the upstream side of the intercooler 18 is detected by the addition field state detection device 98, and the ECU 42 controls the opening and closing of the addition valve 40 in accordance with this state. That is, the intake air flow velocity in the intake pipe 16 in the NOx addition field on the upstream side of the intercooler 18 is detected to determine whether or not NOx can be added. The engine 10 normally has a plurality of cylinders 10a, and the timing of opening the intake valve 60 of each cylinder is shifted. Further, on the upstream side of the intercooler 18, the flow of the intake air is averaged to some extent, but the intake air amount greatly varies depending on the output torque, the engine speed, and the like. In the present embodiment, the addition of NOx is permitted when the intake flow velocity detected by the addition field state detection device 98 is equal to or higher than a predetermined value. Of course, it is also considered that NOx can be added from the operating state of the engine 10 described above.

  It is also preferable that the intake valve 60 is open and the EGR valve 29 is closed. Thereby, it is ensured that the flow velocity in the intake pipe 16 is not less than a predetermined value.

  Here, when the driving state of the vehicle changes, the state in the intake pipe 16 changes greatly. In this example, it takes a predetermined time until the added NOx actually reaches the cylinder 10a of the engine 10. Therefore, even if it is determined from the operating state of the engine 10 that NOx may be added, the state may change when NOx is actually supplied into the cylinder 10a of the engine 10. Therefore, it is preferable to control to add NOx during steady operation. Furthermore, when liquid NOx is added, it is preferable that the temperature in the vicinity of the intake valve 60 is equal to or higher than a predetermined value, and thus liquid NOx can be prevented from adhering to the intake pipe 16. In FIG. 17, NOx is added upstream of the intercooler 18, but it may be added between the intake valve 90 and the intercooler 18.

"EGR pipe addition"
FIG. 18 shows an example in which NOx is added to the upstream side of the EGR cooler 30 of the EGR pipe. In this example, the addition field state detection device 98 detects the upstream state of the EGR cooler 30 to which NOx is added, and controls the addition of NOx by opening and closing the addition valve 40 based on the detection result. In this case, as in the case of addition to the intake pipe 16 described above, it is preferable to add NOx when the flow rate in the EGR pipe 28 is equal to or higher than a predetermined value. In this example, it is preferable to make it a condition that it is a steady operation like the above-mentioned addition in the intake pipe, and it is good to make it a condition that the EGR valve 29 is in the lower order. Furthermore, when adding liquid NOx, it is also preferable that the temperature is limited to a predetermined temperature or higher.

  The gas flowing in the EGR pipe 28 originally contains NOx, and the NOx concentration can be further increased by adding NOx thereto. It is easy to keep the NOx concentration supplied to the cylinder 10a of the engine 10 high. Therefore, it is preferable to supply NOx into the EGR pipe 28.

"Control of the location of addition"
FIG. 19 shows an example in which a plurality of addition sites are prepared. That is, (i) in the cylinder 10a, (ii) in the intake pipe 16 near the intake valve, (iii) in the intake pipe 16 on the upstream side of the intercooler 18, and (iv) in the EGR pipe on the upstream side of the EGR cooler 30. One addition location is prepared, and NOx can be added by selecting any location by controlling the opening and closing of the corresponding addition valves 40a to 40d.

  And the state of four addition places is each detected by the addition place state detection apparatus 98, and NOx is selectively added with respect to an appropriate addition place.

  FIG. 20 shows the selection of four addition locations. (1) (iv) Addition in the EGR pipe 28, (2) (iii) In the intake pipe 16 upstream of the intercooler 18, (3) (ii) In the intake pipe 16 near the intake valve, ( 4) The order of (i) in the cylinder 10a is adopted. As a result, (1) EGR valve open, addition place temperature is a predetermined temperature or more, in the EGR pipe in the case of steady operation, (2) Other than the above (1), EGR valve closed, intake valve open, in the intake pipe in the case of steady operation, (3) Other than the above (1) and (2), when the temperature near the intake valve is higher than a predetermined value, near the intake valve; Is added.

  FIG. 21 shows a flowchart of processing in this example.

  Thus, the NOx concentration in the NOx storage tank 24 is measured (S221), and if it is equal to or greater than a predetermined value (S222), the operating state of the engine 10 is taken in (S223), and it is determined whether the operating state can purify NOx. (S224) If the state can be purified, the addition site state detection device 98 detects the states of the four addition sites (S225). Then, according to the above-mentioned priority order, the addition location is determined (S226), the NOx supply pump 38 is operated, and NOx is added to an appropriate addition location (S227). In addition, it is also suitable to add NOx gas to an addition place via the NOx converter 56 and the NOx storage tank 58.

  If the value is not more than the set value in S222 and cannot be purified in S224, the process ends without adding NOx.

  Thus, by preparing four addition sites and selecting the addition site according to the conditions of the addition site, it is possible to increase the state where NOx can be added, and by selecting the optimal addition site and adding NOx can do.

<Sixth Embodiment>
Hereinafter, a sixth embodiment will be described based on the drawings. FIG. 23 is a diagram showing a configuration of the present embodiment. About the structure similar to the above-mentioned 1st-5th embodiment, the same number is attached | subjected and description is abbreviate | omitted.

"Thermal decomposition of nitrates"
Here, in the collection liquid, NOx is basically dissolved in water to be in a nitrate state. Such nitric acids do not function as NOx during the above-described combustion reaction in the cylinder 10a and cannot sufficiently reduce NOx. Therefore, in the example of FIG. 23, the collected liquid containing nitric acid in the NOx storage tank 24 is supplied to the NOx conversion device 56 by the NOx supply pump 38, where the nitric acid is decomposed into NOx. That is, nitric acids are decomposed into gaseous NOx (NO ₂ or NO) by the following reaction (thermal decomposition).
4HNO ₃ → 4NO + 2H ₂ O + O ₂
2NO ₂ ← → 2NO + O ₂

  In the NOx conversion device 56, thermal decomposition is used for decomposition of nitric acids. In the example of FIG. 23, the heat recovery unit 102 recovers engine exhaust heat (exhaust heat) and uses it for heat during decomposition of nitric acids. For example, a heat pump can be used for this heat recovery. Thus, the energy saving of the system can be achieved by utilizing the engine exhaust heat. Note that the NOx conversion device 56 may be disposed so as to be in contact with the exhaust pipe 12 or the engine, or connected through a heat transfer material, and the NOx conversion device 56 may be heated by heat transfer from the engine exhaust heat. .

  In this example, the NOx conversion device 56 includes a decomposition unit 56a in which a thermal decomposition reaction is performed and a heater 56b. The heater 56b is preferably an electric heater that is easy to control the temperature, whereby the temperature in the decomposition unit 56a can be controlled to an appropriate temperature. The heat recovered in the heat recovery unit 102 is preferably used for preheating the collected liquid, and the temperature in the NOx conversion device 56 is preferably controlled by the heater 56b. Further, an oxidation catalyst may be used in combination as the heater 56b.

  Furthermore, it is preferable to dispose a nitric acid decomposition catalyst in the decomposition unit 56a to promote thermal decomposition of nitric acids. The nitric acid decomposition catalyst is preferably platinum, iron, copper, zinc, gold, silver, silicon, aluminum, manganese, chromium, nickel, vanadium, titanium, zirconium, molybdenum, tungsten, platinum, palladium, rhodium, ruthenium, iridium and At least one or two or more metals selected from the group consisting of lanthanoid elements or oxides thereof can be used. These nitric acid decomposition catalysts may be used by being supported on a carrier, or may be applied to the wall of the decomposition portion 56a.

  In addition, for thermal decomposition of nitric acid, it is preferable to heat to several hundred degrees C (about 200-500 degrees C), and it is suitable to utilize the exhaust heat of an engine for this purpose. Moreover, the higher the NOx concentration in the converted NOx gas, the better. Therefore, when the NOx concentration detected by the NOx sensor 32 is equal to or higher than a predetermined value, the collected liquid may be sent to the NOx conversion device 56.

“Addition of NOx”
Here, in the example of FIG. 23, the NOx gas from the NOx conversion device 56 is supplied to the upstream side of the EGR cooler 30 of the EGR pipe 28 via the addition valve 40b, and is also supplied to the intake pipe 16 via the addition valve 40d. To the upstream side of the intercooler 18. The opening and closing of the addition valves 40b and 40d is controlled by the ECU 42. The ECU 42 selects appropriate addition valves 40 b and 40 d from the operating state of the engine 10 and adds NOx to the intake side of the engine 10. Both the addition valves 40b and 40d may be opened at a time, or only one addition valve 40b and 40d may be used.

  In this way, by supplying NOx gas to the EGR pipe 28 and the intake pipe 16, the NOx concentration in the intake air of the engine 10 can be increased, and NOx can be reduced during combustion in the cylinder 10a of the engine 10. it can.

“Installation on EGR pipe”
In the example of FIG. 24, the NOx conversion device 56 is configured using the EGR pipe 28. That is, the NOx supply pump 38 adds a collection liquid containing nitric acid into the EGR pipe 28, and the NOx conversion device 56 is disposed downstream thereof. The NOx conversion device 56 uses a part of the EGR pipe 28 as the decomposition unit 56 a of the NOx conversion device 56. A heater 56b is provided around the EGR pipe 28 of the decomposition unit 56a to control the temperature of the decomposition unit 56a appropriately. Further, a nitric acid decomposition catalyst layer is formed on the inner wall of the EGR pipe 28 of the decomposition portion 56a. The NOx conversion device 56 may be separated from the EGR pipe 28 and formed as a separate pipe so that it can be removed from the EGR pipe 28. For example, flanges may be formed at both ends of the NOx conversion device 56 and fixed to the EGR pipes 28 on both sides by bolting.

  Moreover, it is good to provide an injection valve as the addition valve 40 which adds a collection liquid toward the decomposition part 56a. The injection valve may control the injection amount by the ECU 42 from the NOx amount of the collected liquid and the engine operating conditions. Since the collected liquid is directly added to the decomposition unit 56a, an apparatus and energy for vaporizing the collected liquid are not necessary.

  The disassembling part 56 a is disposed on the upstream side of the EGR cooler 30. Accordingly, the gas that subsequently passes through the decomposition unit 56a is cooled in the heat exchanger of the EGR cooler 30, and the condensed water is separated. Therefore, in the cylinder 10a of the engine 10, the production of nitric acid due to the reaction of NOx and water is suppressed.

  A pipe and a pump may be installed in the EGR cooler 30 and the condensed water may be transferred to the NOx storage tank 24. Thereby, it is not necessary to replenish the NOx storage tank 24 with water, and continuous exhaust purification can be performed.

  By installing the NOx conversion device 56 in the EGR pipe 28, unburned hydrocarbons and CO in the exhaust gas act as a reducing agent. Therefore, decomposition of nitric acid is promoted in the NOx conversion device 56. Further, the temperature of the gas in the EGR pipe 28 is lowered by the latent heat of vaporization of the collected liquid, and the intake air temperature of the engine 10 can be lowered.

"Installation in the intake pipe"
In the example of FIG. 25, the NOx conversion device 56 is configured using the intake pipe 16. That is, the NOx supply pump 38 adds a collection liquid containing nitric acid into the intake pipe 16, and the NOx conversion device 56 is disposed downstream thereof. The NOx conversion device 56 uses a part of the intake pipe 16 as the decomposition unit 56a. Further, a heater 56b is provided around the EGR pipe 28 of the decomposition unit 56a to control the temperature of the decomposition unit 56a to an appropriate one.

  A layer of nitric acid decomposition catalyst may be formed on the inner wall of the intake pipe 16 of the decomposition portion 56a. Further, the disassembly portion 56a of the intake pipe 16 may be formed as a separate pipe and fixed to the intake pipe 16 by bolting.

  Also in this example, since the decomposition part 56a of the NOx conversion device 56 is arranged upstream of the intercooler 18, the gas that has passed through the decomposition part 56a is cooled in the intercooler 18 and the condensed water is separated. Therefore, in the cylinder 10a of the engine 10, the production of nitric acid due to the reaction of NOx and water is suppressed.

  If the water condensed in the intercooler 18 is transferred to the NOx storage tank 24, it is not necessary to replenish the NOx storage tank 24 with water, and continuous exhaust purification can be performed. Also, with this configuration, the intake air temperature is expected to decrease due to the latent heat of vaporization of the collected liquid.

"Adding NOx to multiple locations"
In the example of FIG. 26, an NOx conversion device 56 is provided separately from the exhaust flow path and intake flow path of the configuration of FIG. 23 described above, but also in the cylinder 10a of the engine 10 via the addition valve 40a. The NOx obtained by the NOx converter 56 can be supplied.

  Depending on the operating state of the engine 10, in particular, whether the engine 10 is in the intake process or whether the EGR valve 29 is opened or closed, which route the NOx should be supplied to the engine 10 differs. It is preferable that the ECU 42 detects the operating state of the engine 10 and controls the opening timing of the addition valve 40 at an appropriate timing.

  In order to prevent NOx produced in the decomposition unit 56a from reacting with water to form nitric acid, it is also preferable to install a heater in the NOx pipe.

"Configuration using piping"
FIG. 27 schematically shows a configuration example of the NOx conversion device 56. This is an example in which the space in the pipe is used as the nitrate decomposition section. A nitric acid decomposition catalyst 56c for promoting thermal decomposition is formed in layers on the inner wall of the EGR pipe 28 and the intake pipe 16, and a corresponding pipe internal space is a decomposition portion 56a. The nitric acid decomposition catalyst 56c can be formed by applying a nitric acid decomposition catalyst or fixing a carrier carrying the nitric acid decomposition catalyst. In this example, the tube forming the disassembling portion 56a is formed independently of the EGR tube 28 and the intake tube 16, and is inserted in the middle.

  And by injecting a liquid collection liquid from the addition valve 40 to the upstream part of the decomposition part 56a, while a collection liquid evaporates, nitric acid is thermally decomposed to NOx. And since there exists the nitric acid decomposition catalyst 56c, thermal decomposition of nitric acid is accelerated | stimulated. In addition, the heater 56b is provided in the outer peripheral side of piping, and performs the suitable heating of the decomposition | disassembly part 56a.

  In the example of FIG. 28, a nitric acid decomposition catalyst 56c made of a porous material is disposed in the decomposition portion 56a in the pipe. The nitric acid decomposition catalyst 56c is installed in the decomposition unit 56a in a form in which the catalyst is meshed or supported on a carrier having various shapes such as a honey comb. Any form may be used as long as the thermal decomposition of nitric acid in the added collection liquid can be efficiently performed without impeding the gas flow.

“Use of engine exhaust heat”
In the example of FIG. 29, the collected liquid is injected into the intake pipe 16 in the vicinity of the intake valve 60 of the engine 10, and a layer of the nitric acid decomposition catalyst 56c is formed on the back surface (upper surface) side of the intake valve. . Since the intake valve 60 is heated by the exhaust heat of the engine 10, the collected liquid supplied here is immediately vaporized and thermally decomposed. The collection liquid is injected at the timing when the intake valve 60 is opened. The collection liquid is vaporized and thermally decomposed and is directly drawn into the cylinder 10a. If the temperature required for thermal decomposition can be obtained only by engine exhaust heat or exhaust heat, it is not necessary to install a heater. In addition, any metal part such as a diffusion plate in the pipe and various valves can be used as the nitric acid decomposition part.

"Use of addition valve"
FIG. 30 shows an example in which the inside of the NOx addition valve 40 is used as a nitric acid decomposition unit. The NOx addition valve 40 is installed in the intake pipe 16 (FIG. 23), the EGR pipe 28 (FIG. 23), or the cylinder 10a of the engine 10 (FIG. 26). Then, a layer of the nitric acid decomposition catalyst 56c is formed on the inner wall in the pipe on the upstream side of the addition valve 40. A heater 56b is disposed around the pipe. As a result, the collection liquid is heated and vaporized inside the addition valve 40, and nitric acid is thermally decomposed, and NOX is ejected from the addition valve 40. In addition, when the temperature required for thermal decomposition can be obtained only by engine exhaust heat, the heater 56b need not be installed.

  DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 2 Collection apparatus, 3 Storage tank, 4 Addition apparatus, 5 Addition field state detection apparatus, 6 Controller, 10 Engine, 10a cylinder, 12 Exhaust pipe, 14 Turbocharger, 15 Air filter, 16 Intake pipe, 18 Intercooler, 20 NOx collection device, 22 Storage medium, 24 NOx storage tank, 26 Circulation pump, 28 EGR pipe, 29 EGR valve, 30 EGR cooler, 32 NOx sensor, 34 Speed / torque sensor, 36 NOx supply pipe, 38 NOx supply pump, 40 addition valve, 42 ECU, 44 storage means, 50 oxidant generator, 52 oxidant supply valve, 54 reformer, 56 NOx converter, 58 NOx storage tank, 60 intake valve, 62 cam, 64 Interlocking mechanism, 70 NOx supply pipe, 72 rotational position measuring device, 74, 82 jet Injection control device, 80 valve open / close detection device, 90 intake valve, 94, 96 pressure sensor, 98 addition field state detection device, 100 iso-output line.

Claims (7)

And occlusion media occlude NOx,
Occlusion means for occluding NOx contained in the exhaust gas of the internal combustion engine in the occlusion medium;
Supply means for supplying NOx stored in the storage medium to a combustion chamber of the internal combustion engine;
Detecting means for detecting the amount of NOx occluded in the occlusion medium;
Rotational speed torque detecting means for detecting the rotational speed and torque of the internal combustion engine;
The amount of NOx stored in the storage medium exceeds a predetermined value , and the NOx amount supplied to the combustion chamber is determined based on the NOx amount supplied to the combustion chamber, the rotational speed and torque of the internal combustion engine, and A purification rate indicating a difference obtained by subtracting the amount of NOx discharged from the internal combustion engine is obtained, and when the purification rate is 0% or more, the supply means is controlled to store NOx stored in the storage medium into the combustion chamber. Control means to supply;
An exhaust gas purification apparatus for an internal combustion engine. An exhaust emission control device for an internal combustion engine according to claim 1,
Reforming means for reforming NOx contained in the exhaust gas of the internal combustion engine into nitric acid;
Further comprising
The storage means stores the nitric acid in the storage medium.
An exhaust emission control device for an internal combustion engine. An exhaust emission control device for an internal combustion engine according to claim 2,
The reforming means adds an oxidant to the exhaust gas of the internal combustion engine.
An exhaust emission control device for an internal combustion engine. An exhaust emission control device for an internal combustion engine according to claim 2,
The modifying means adds an oxidizing agent to the storage medium.
An exhaust emission control device for an internal combustion engine. An exhaust emission control device for an internal combustion engine according to claim 1,
The occlusion medium is water or an aqueous solution.
An exhaust emission control device for an internal combustion engine. An exhaust emission control device for an internal combustion engine according to claim 1,
NOx occluded in the occlusion medium is present as nitric acid or nitrate ions.
An exhaust emission control device for an internal combustion engine. An exhaust emission control device for an internal combustion engine according to claim 1,
Storage means for storing the storage medium;
A circulating means for circulating the storage medium between the storage means and the storage means;
An exhaust emission control device for an internal combustion engine, further comprising: