JP2015031258A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat NOx in exhaust gas using an engine.SOLUTION: An exhaust emission control device includes a NOx trapping device 2 using medium for trapping NOx from exhaust gas from an internal combustion engine 1 to obtain NOx trapped medium, a NOx storage tank 3 for storing the obtained trapped medium, an addition device 4 for adding the trapped medium in the NOx storage tank via an intake system for the internal combustion engine or directly into a combustion cylinder of the internal combustion engine, an addition site state detection device 5 for detecting the state of an addition site where the trapped medium is added by the NOx trapped medium addition device, and a controller 6 for controlling an addition timing for the trapped medium depending on the detected state of the addition site.

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that purifies NOx in the exhaust gas of the internal combustion engine.

  Non-Patent Document 1 proposes that NOx gas in engine exhaust gas is adsorbed, then desorbed, and that NOx is added again to the engine. As a premise of such a method, there is a report that NO gas concentration in exhaust gas was examined by mixing NO gas into engine intake air. According to this experimental report, it is shown that NOx in the exhaust gas is reduced compared with the amount of NOx in the intake air after adding NO, and NOx is decomposed in the engine.

  Japanese Patent Application Laid-Open No. H10-228707 discloses a device for supplying fuel and directly injecting into a cylinder as a device for supplying fuel. These injectors are devices for supplying fuel to the internal combustion engine, but have been shown to select the timing of injection.

JP-A-2005-337104

Nakano et al., “Reduction of exhaust gas by re-inhalation of NOx using a diesel engine”, Japan Society for Automotive Engineers, Preprint of Academic Lecture, No. 108-04

  As an apparatus for removing NOx in engine exhaust gas, an exhaust gas treatment apparatus using a catalyst is generally used. However, this catalyst has insufficient capacity depending on conditions such as a low temperature, or has a problem of deterioration.

  Moreover, what is described in Non-Patent Document 1 only shows the principle possibility, and an actual exhaust gas treatment apparatus has not been proposed.

  There is a demand for a feasible apparatus that can perform NOx treatment more effectively than conventional catalysts.

  Patent Document 1 shows an apparatus for injecting fuel, and does not relate to the treatment of NOx in exhaust gas.

  In the exhaust gas purification apparatus for an internal combustion engine according to the present invention, as shown in FIG. 14, a NOx collection device 2 that obtains a NOx collection medium by collecting NOx in the exhaust gas of the internal combustion engine 1 with a medium is obtained. The NOx storage tank 3 that stores the collected medium and the NOx collected in the collection medium of the NOx storage tank are added via the intake system of the engine of the internal combustion engine or directly into the combustion cylinder of the internal combustion engine. The addition device 4, the addition field state detection device 5 that detects the state of the addition field to which NOx is added by the addition device, and the addition timing of NOx by the addition device are controlled according to the detected state of the addition field And a controller 6 for performing.

  In the embodiment, the collection medium is a liquid, and the addition device adds the collection medium as it is.

  In another embodiment, the collection medium is a liquid, and further includes a NOx conversion device that converts the collection medium from the NOx storage tank into gaseous NOx, and the addition device includes the NOx. Add the NOx obtained in the converter.

  In still another embodiment, the collection medium is a liquid, and the NOx collection device collects NOx in the medium as a nitric acid by bringing a liquid containing water and exhaust into contact with each other. Get.

  In still another embodiment, the addition device adds NOx into the combustion cylinder, the addition field state detection device detects a pressure in the combustion cylinder, and the controller responds to the detected pressure. When the pressure is within an appropriate range, the adding device is controlled to add NOx into the combustion cylinder.

  In still another embodiment, the addition device adds NOx into an intake pipe near the intake valve of the combustion cylinder, the addition field state detection device detects an open / close state of the intake valve, and the controller The addition device is controlled to add NOx into the intake pipe when the intake valve is in an open state.

  In still another embodiment, the addition field state detection device is configured by a mechanical mechanism that interlocks with opening and closing of the intake valve, and the controller adds NOx in conjunction with the mechanical mechanism. The addition device is mechanically controlled.

  In still another embodiment, the addition device adds NOx in the intake pipe upstream of the intake valve, and the addition field state detection device detects a flow state of intake air in the intake pipe. The controller controls the addition of NOx by the addition device based on the detected flow state of the intake air.

  In still another embodiment, the EGR system circulates exhaust gas to the intake pipe, and the addition device adds NOx to the upstream side of the EGR cooler that cools the circulating gas in the EGR system, The addition field state detection device detects a flow state of the circulating gas of the EGR system, and the controller controls addition of NOx by the addition device based on the detected flow state of the circulation gas.

In still another embodiment, an EGR system that circulates exhaust gas to the intake pipe is provided.
(I) The addition device adds NOx into the combustion cylinder, the addition field state detection device detects the pressure in the combustion cylinder, and the controller detects the pressure within an appropriate range according to the detected pressure. A mode for controlling the addition device to add NOx into the combustion cylinder when in
(Ii) The addition device adds NOx into the intake pipe near the intake valve of the combustion cylinder, the addition field state detection device detects the open / closed state of the intake valve, and the controller opens the intake valve. A mode for controlling the addition device to add NOx into the intake pipe when in a state;
(Iii) The addition device adds NOx in the intake pipe to the combustion cylinder and upstream of the intake valve, and the addition field state detection device detects a flow state of intake air in the intake pipe, The controller controls the addition of NOx by the addition device based on the detected flow state of the intake air; and
(Iv) The addition device adds NOx to the upstream side of the EGR cooler that cools the circulating gas in the EGR system, and the addition field state detection device detects the flow state of the circulating gas in the EGR system. The controller controls the addition of NOx by the addition device based on the detected flow state of the circulating gas; and
Select one of the following.

  Thus, according to the present invention, NOx can be supplied to the engine to process NOx.

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.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described herein.

"Overall configuration of the device"
FIG. 1 is a diagram illustrating a configuration of the embodiment. The engine 10 that is an internal combustion engine is, for example, a diesel engine, but may be a gasoline engine. In the figure, description of the fuel supply mechanism is omitted, but the fuel and the air are injected so that the fuel is injected directly into the cylinder (cylinder) 10a of the engine or to the intake air, and proper combustion is performed in the cylinder 10a. Is controlled.

  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.

  Further, an EGR (exhaust gas circulation) pipe 28 in which an EGR cooler 30 is arranged in the middle is arranged between the exhaust valve of the exhaust pipe 12 and the turbocharger 14 and between the intake valve of the intake pipe 16 and the intercooler 18. Thus, a part of the exhaust can be returned to the intake side. The EGR pipe 28 is provided with an EGR valve 29 for controlling the timing and amount of exhaust gas circulation.

Here, the collection medium for collecting NOx in the NOx collection apparatus 20 is preferably a liquid, particularly a liquid containing water, but may be a gas. In the present embodiment, the NOx collection device 20 sprays water as a collection medium (collection liquid) on exhaust gas, or makes the exhaust gas and the collection liquid come into gas-liquid contact via a permeable membrane, thereby NOx inside is collected as nitric acid. Note that NOx is, for example, NO (nitrogen monoxide) or NO ₂ (nitrogen dioxide), but N ₂ O (zinc nitride), N ₂ O ₅ (dinitrogen pentoxide), N ₂ O ₃ , N ₂ O ₄ , HNO ₃ , NO ₃ , HNO _{2 and the} like are also included.

  The collected liquid is stored in the NOx storage tank 24. The NOx collection device 20 is filled with a filler for gas-liquid contact (for example, a honey comb, a monolith porous material, a material having a large contact area, such as a lasing ring), and the collected liquid is collected from above. A scrubber type that diffuses and jets and makes alternating current contact with the exhaust gas is adopted, but the flow of the exhaust gas may be in an upward flow or a horizontal direction, and may not be filled with a filler. Alternatively, a membrane-type gas-liquid contact device that diffuses exhaust gas (particularly NOx) into the collected liquid through a gas permeable membrane may be used. Further, as described above, water is suitable for collecting NOx, but alcohol may be used as long as NOx can be collected. Usually, water or an aqueous solution of an inorganic salt is used, whereby NOx is effectively collected, and the collected solution is an aqueous solution of nitric acid or an alkali metal salt, alkaline earth metal salt or ammonium salt of nitric acid.

  The NOx storage tank 24 is provided with a NOx sensor 32, and the NOx concentration in the collected liquid is measured. As the NOx sensor 32, a nitric acid sensor or the like is used, but a pH meter or the like may be used as long as an appropriate calibration curve is obtained. If the NOx concentration in the collected liquid is low, the NOx concentration in the atmosphere cannot be sufficiently increased when the collected liquid (or gasified NOx) enters the cylinder 10a, and NOx cannot be reduced. Therefore, based on the detection value of the NOx sensor 32, the NOx concentration of the collected liquid is detected.

  Further, the NOx storage tank 24 is provided with a circulation pump 26, and the collection liquid in the tank is circulated to the NOx collection device 20. The collected liquid from the NOx collection device 20 is preferably transported to the NOx storage tank 24 by gravity.

  A NOx supply pump 38 is connected to the NOx storage tank 24, and a NOx supply pipe 36 is connected to the NOx supply pump 38. The collected NOx is supplied to the cylinder 10a of the engine.

Here, in the cylinder of the engine 10, the fuel burns using oxygen in the air and carbon dioxide gas is generated, but NOx is also generated in a high heat state. However, this NOx reaction is a Zeldovich mechanism (NO equilibrium reaction) (N ₂ + O⇔NO + N, O ₂ + N⇔NO + O, N + OH⇔NO + H). As a result of various experiments, it has been found that the amount of NOx in the exhaust gas after combustion can be reduced with respect to NOx supplied into the cylinder 10a of the engine 10 if conditions are selected.

  Therefore, in the present embodiment, the ECU 42 as a controller controls the timing at which NOx is added into the cylinder 10a. As a result, in the engine 10, the above-described conditions for reducing NOx are maintained, and NOx emission is reduced to almost zero, thereby enabling the operation of the engine 10.

Here, in this embodiment, in order to reduce NOx emission to 0, it is necessary that the following purification rate is greater than 0%.
Purification rate = {(NOx supply amount−NOx discharge amount) / (NOx supply amount)} × 100 (%)

  As described above, the purification rate is 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.

  From the operating conditions of the engine 10 such as the engine output torque and the engine speed and the supply amount and discharge amount of NOx at that time, the purification rate is examined in advance and stored as a map so that the ECU 42 Based on the operating conditions of the engine 10, it is determined how much the NOx concentration in the intake air can be purified, and the supply of NOx to the engine 10 is controlled.

  The ECU 42 controls fuel injection and other operations of the engine 10 from the accelerator depression amount, the engine speed, and the like, and also controls the collected liquid. The engine state detector 34 detects engine output torque, engine speed, etc., and supplies a detection signal to the ECU 42. As for the actual operation control of various devices, the controller receives a signal from the ECU 42, and the controller controls the operation of the various devices. However, the description of this controller is omitted.

"In-cylinder addition"
Here, in the example shown in FIG. 1, 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. 2 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. 3 shows only the collection liquid supply system 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. 4, the flowchart of the collection liquid addition control by ECU42 in the structure of FIG.2, 3 is shown.

  First, the NOx concentration in the collected liquid is measured by the NOx sensor 32 (S11), and the measured NOx concentration is compared with a set value (S12). The amount of NOx added is preferably 2.5 l / min or more.

  If the NOx concentration is equal to or higher than a predetermined value, the engine speed and output torque (these are always grasped in the vehicle) are taken in (S13), and whether the engine 10 is in an operation state in which NOx can be purified from the operation state. Determine (S14). If it can be purified, the NOx supply pump 38 is operated to add the collected liquid to the NOx converter 56 (S15).

  The internal pressure of the cylinder 10a and the internal pressure (injection pressure) of the NOx (gas) storage tank 58 are compared (S16). 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 (S17).

  Note that if the injection pressure is lower than the set value in S12, cannot be purified in S14, and the injection pressure is lower in S16, 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. 5 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. 6 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. 6, 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. 7 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. 8 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 open / close detection device 80, and the injection control device 82 controls the addition of NOx by opening the addition valve 68 when the intake valve 60 is open.

  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. 9 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. 9, NOx is added to the upstream side of the intercooler 18, but it may be added between the intake valve 90 and the intercooler 18.

"EGR pipe addition"
FIG. 10 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. 11 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. 12 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. 13 shows a flowchart of processing in this example.

  In this way, the NOx concentration in the NOx storage tank 24 is measured (S21), and if it is equal to or greater than a predetermined value (S22), the operating state of the engine 10 is taken in (S23), and it is determined whether the operating state can purify NOx. (S24) If the state can be purified, the addition site state detection device 98 detects the states of the four addition sites (S25). Then, according to the above-mentioned priority order, the addition location is determined (S26), the NOx supply pump 38 is operated, and NOx is added to an appropriate addition location (S27). 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.

  In addition, when it is below setting value in S22 and cannot purify | clean in S24, addition of NOx is not performed but a process is complete | finished.

  In this way, four addition sites are prepared, and by 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 the optimum addition site is selected and NOx is added. can do.

  DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 2 NOx collection device, 3 NOx storage tank, 4 Addition device, 5 Addition field state detection device, 6 Controller, 10 Engine, 10a cylinder, 12 Exhaust pipe, 14 Turbocharger, 15 Air filter, 16 Intake pipe , 18 Intercooler, 20 NOx collection device, 24 NOx storage tank, 26 Circulation pump, 28 EGR pipe, 29 EGR valve, 30 EGR cooler, 32 NOx sensor, 36 NOx supply pipe, 38 NOx supply pump, 40 Addition valve, 42 ECU, 60 intake valve, 62 cam, 64 interlocking mechanism, 70 NOx supply pipe, 72 rotational position measuring device, 74, 82 injection control device, 80 valve open / close detection device, 56 NOx conversion device, 58 NOx storage tank, 90 intake valve 94,96 Pressure sensor, 98 Addition field state detection device,

Claims (10)

A NOx collection device for collecting NOx in the exhaust gas of the internal combustion engine with a medium to obtain a NOx collection medium;
A NOx storage tank for storing the obtained collection medium;
An addition device for adding the NOx collected in the collection medium of the NOx storage tank to the combustion cylinder of the internal combustion engine via the intake system of the engine of the internal combustion engine or directly;
An addition field state detection device for detecting the state of the addition field where NOx is added by the addition device;
A controller for controlling the addition timing of NOx by the addition device according to the detected state of the addition field;
An exhaust purification device for an internal combustion engine, comprising: The exhaust gas purification apparatus for an internal combustion engine according to claim 1,
The collection medium is a liquid;
The addition device is an exhaust gas purification device for an internal combustion engine, in which the collection medium is added as it is. The exhaust gas purification apparatus for an internal combustion engine according to claim 1,
The collection medium is a liquid;
A NOx conversion device for converting the collection medium from the NOx storage tank into gaseous NOx;
The addition device is an exhaust gas purification device for an internal combustion engine, which adds NOx obtained in the NOx conversion device. The exhaust emission control device for an internal combustion engine according to any one of claims 1 to 3,
The collection medium is a liquid;
The NOx collection device is an exhaust gas purification device for an internal combustion engine, which contacts a liquid containing water and exhaust gas, collects NOx in a medium as nitric acid, and obtains a collection medium. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4,
The addition device adds NOx into the combustion cylinder,
The addition field state detection device detects the pressure in the combustion cylinder,
The controller controls the addition device to add NOx into the combustion cylinder when the pressure is within an appropriate range according to the detected pressure.
An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4,
The addition device adds NOx into the intake pipe near the intake valve of the combustion cylinder,
The addition field state detection device detects an open / close state of the intake valve,
The controller controls the addition device to add NOx into the intake pipe when the intake valve is in an open state;
An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to claim 6,
The addition field state detection device is composed of a mechanical mechanism that interlocks with opening and closing of the intake valve,
The controller mechanically controls the addition device to add NOx in conjunction with the mechanical mechanism;
An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4,
The addition device adds NOx in the intake pipe upstream of the intake valve,
The addition field state detection device detects a flow state of intake air in the intake pipe,
The controller controls addition of NOx by the addition device based on the detected flow state of the intake air;
An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4,
It has an EGR system that circulates exhaust to the intake pipe,
The addition device comprises:
NOx is added to the EGR system upstream of the EGR cooler that cools the circulating gas,
The addition field state detection device detects a flow state of the circulating gas of the EGR system,
The controller controls addition of NOx by the addition device based on the detected flow state of the circulating gas.
An exhaust purification device for an internal combustion engine. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4,
It has an EGR system that circulates exhaust to the intake pipe,
(I) The addition device adds NOx into the combustion cylinder, the addition field state detection device detects the pressure in the combustion cylinder, and the controller detects the pressure within an appropriate range according to the detected pressure. A mode for controlling the addition device to add NOx into the combustion cylinder when in
(Ii) The addition device adds NOx into the intake pipe near the intake valve of the combustion cylinder, the addition field state detection device detects the open / closed state of the intake valve, and the controller opens the intake valve. A mode for controlling the addition device to add NOx into the intake pipe when in a state;
(Iii) The addition device adds NOx in the intake pipe to the combustion cylinder and upstream of the intake valve, and the addition field state detection device detects a flow state of intake air in the intake pipe, and the controller Is a mode for controlling the addition of NOx by the addition device based on the detected flow state of the intake air; and
(Iv) The addition device adds NOx to the upstream side of the EGR cooler that cools the circulating gas in the EGR system, and the addition field state detection device detects the flow state of the circulating gas in the EGR system. The controller controls the addition of NOx by the addition device based on the detected flow state of the circulating gas; and
Select one of the
An exhaust purification device for an internal combustion engine.