JP6090134B2 - Highly active substance addition equipment - Google Patents

Description

  The present invention relates to a highly active substance addition apparatus for adding a reducing agent used for NOx reduction.

Conventionally, a technique is known in which NOx (nitrogen oxides) contained in exhaust gas from an internal combustion engine is adsorbed on a catalyst, and the adsorbed NOx is reacted with a reducing agent on the catalyst to be purified. Patent Document 1 discloses an apparatus including a reducing agent pump that adds a reducing agent to an exhaust passage, and an ozone generator that generates ozone and adds it to the exhaust passage. According to this apparatus, the reducing agent is reformed by ozone in the exhaust passage, and the reformed reducing agent is supplied to the catalyst, so that the purification ability on the catalyst is improved. Further, according to the above apparatus, NO (nitrogen monoxide) in the exhaust passage is oxidized to NO ₂ (nitrogen dioxide) by ozone. Then, NO ₂ Due to the high adsorption of the catalyst compared to NO, NOx which get through without being adsorbed on the catalyst is reduced.

  However, in the above reducing agent reforming, the reaction rate of ozone with the reducing agent is slow, and further ozone decomposes immediately when the temperature becomes high (for example, 250 ° C. or higher). There is a concern that the reducing agent is supplied to the catalyst without being reformed.

  With respect to this problem, Patent Document 2 discloses a discharge device that modifies a reducing agent by allowing the reducing agent to pass between discharge electrodes. According to this discharge device, since the reducing agent can be directly oxidized and reformed by oxygen gas ionized by discharge without using ozone, the problems of the thermal decomposition and reaction rate of ozone described above are eliminated, and The reforming ability can be improved.

International Publication No. 2013/035663 Pamphlet JP 2009-162173 A

However, although the above-described discharge device can improve the reforming capability as described above, the action of oxidizing NO to NO ₂ by ozone does not occur, and therefore, NOx that is not adsorbed cannot be sufficiently reduced. If an ozone generator is provided separately from the discharge device, the size of the device is increased.

  Even when a catalyst that does not have an adsorption or occlusion function is used, it is necessary to supply ozone separately from reforming of the reducing agent, for example, when ozone is used for regeneration of the PM filter. May be. For this reason, there is room for improvement in the above discharge device that cannot supply ozone.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly active substance addition apparatus that achieves both improvement of the reducing agent reforming ability and the ability to supply ozone. It is in.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

According to a first aspect of the invention, a NOx purifying device (15) for purifying NOx contained in exhaust gas of an internal combustion engine (10) on a reduction catalyst is provided in a combustion system provided in an exhaust passage (10ex), This is a highly active substance addition device for adding a highly active substance from the supply pipe (35) connected to the upstream side of the reduction catalyst in the passage to the exhaust passage. This highly active substance addition device is disposed outside the exhaust passage, and includes a discharge reactor (20) for ionizing oxygen gas by discharge, a hydrocarbon supply means (33) for supplying hydrocarbons to the discharge reactor, Control of hydrocarbon supply means to stop supply, ozone generation control means (S30, S40) for generating ozone as a highly active substance from oxygen gas ionized by the discharge reactor, and supply of hydrocarbons A reforming control means (S50, S60) that oxidizes hydrocarbons with oxygen gas ionized by the discharge reactor to produce a reforming reducing agent as a highly active substance by controlling the hydrocarbon supply means to Bei intake or air of an internal combustion engine, with at least oxygen oxygen supply means for supplying to the discharge reactor as an oxygen gas containing (31,36,37), the The combustion system comprises an intake of an internal combustion engine supercharged for supercharger (11), and the supercharger by cooler for cooling the supercharged air (12), the oxygen supply means (36, 37 ) Supplies a part of the intake air supercharged by the supercharger to the discharge reactor, and supplies the intake air downstream of the cooler to the discharge reactor during the ozone generation by the ozone generation control means. by the time modifier reducing agent generation, it characterized that you supply intake upstream of the cooler to the discharge reactor.
According to a second invention to be disclosed, a NOx purification device (15) that purifies NOx contained in exhaust gas of an internal combustion engine (10) on a reduction catalyst is provided in a combustion system provided in an exhaust passage (10ex), and the exhaust gas is exhausted. This is a highly active substance addition device for adding a highly active substance to the upstream side of the reduction catalyst in the passage. This highly active substance addition apparatus includes a discharge reactor (20) for ionizing oxygen gas by discharge, a hydrocarbon supply means (33) for supplying hydrocarbons to the discharge reactor, and a hydrocarbon so as to stop the supply of hydrocarbons. By controlling the supply means, the ozone generation control means (S30, S40) for generating ozone as a highly active substance from the oxygen gas ionized by the discharge reactor, and the hydrocarbon supply means for carrying out the supply of hydrocarbons By controlling, reforming control means (S50, S60) that oxidizes hydrocarbons with oxygen gas ionized by the discharge reactor to generate a reforming reductant as a highly active substance, and intake air or air of the internal combustion engine, Oxygen supply means (31, 36, 37) for supplying the discharge reactor as oxygen gas containing at least oxygen;
The combustion system includes a supercharger (11) for supercharging the intake air of the internal combustion engine, and a cooler (12) for cooling the intake air supercharged by the supercharger, and an oxygen supply means (36) 37) supplies a part of the intake air supercharged by the supercharger to the discharge reactor, and supplies the intake air downstream of the cooler to the discharge reactor during the ozone generation by the ozone generation control means. When the reforming / reducing agent is generated by the control means, the intake air upstream of the cooler is supplied to the discharge reactor.

According to the first invention and the second invention, by supplying hydrocarbons, the reforming reductant can be generated by oxidizing the hydrocarbons with oxygen gas ionized by the discharge reactor. Therefore, while the reducing agent is reformed with ozone in Patent Document 1 above, the hydrocarbon (reducing agent) can be reformed without using ozone in the above invention. Therefore, the above-described problems such as the thermal decomposition of ozone and the slow reaction rate are solved, and the reforming ability of the reducing agent can be improved.

Further, according to the first and second inventions, ozone can be generated from the oxygen gas ionized by the discharge reactor by stopping the supply of hydrocarbons. Therefore, both the reforming of the reducing agent and the generation of ozone can be realized with one discharge reactor, and both the improvement of the reforming ability of the reducing agent and the supply of ozone can be achieved.

The schematic diagram which shows the combustion system to which the highly active substance addition apparatus which concerns on 1st Embodiment of this invention, and its apparatus are applied. The schematic diagram explaining the mechanism by which ozone is produced | generated in 1st Embodiment. The schematic diagram explaining the mechanism in which reformed HC is generated in a 1st embodiment. The flowchart which shows the procedure of the control which switches ozone production | generation and reformed HC production | generation in 1st Embodiment. The flowchart which shows the procedure of the control which switches ozone production | generation and reformed HC production | generation in 2nd Embodiment of this invention. The flowchart which shows the procedure of the control which switches ozone production | generation and reformed HC production | generation in 3rd Embodiment of this invention. The schematic diagram which shows the highly active substance addition apparatus which concerns on 4th Embodiment of this invention, and the combustion system to which the apparatus is applied. The schematic diagram which shows the combustion system to which the highly active substance addition apparatus which concerns on 5th Embodiment of this invention, and its apparatus are applied. The flowchart which shows the procedure of the control which switches ozone production | generation and reformed HC production | generation in 5th Embodiment.

  Hereinafter, a plurality of modes for carrying out the invention will be described with reference to the drawings. In each embodiment, portions corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals and redundant description may be omitted. In each embodiment, when only a part of the configuration is described, the other configurations described above can be applied to other portions of the configuration.

(First embodiment)
The combustion system shown in FIG. 1 includes an internal combustion engine 10, a supercharger 11, a particulate collection device (DPF 14), a NOx purification device 15, a reducing agent purification device (DOC 16), and a highly active substance addition device, which will be described in detail below. . The combustion system is mounted on a vehicle, and the vehicle travels using the output of the internal combustion engine 10 as a drive source. The internal combustion engine 10 is a compression self-ignition diesel engine, and light oil is used as a fuel for combustion.

  The supercharger 11 includes a turbine 11a, a rotating shaft 11b, and a compressor 11c. The turbine 11a is disposed in the exhaust passage 10ex of the internal combustion engine 10 and rotates by the kinetic energy of the exhaust. The rotating shaft 11b couples the impellers of the turbine 11a and the compressor 11c to transmit the rotational force of the turbine 11a to the compressor 11c. The compressor 11c is disposed in the intake passage 10in of the internal combustion engine 10, compresses the intake air, and supercharges the internal combustion engine 10.

  A cooler 12 for cooling the intake air compressed by the compressor 11c is disposed on the downstream side of the compressor 11c in the intake passage 10in. The compressed intake air cooled by the cooler 12 is adjusted in flow rate by a throttle valve 13 and then distributed to a plurality of combustion chambers of the internal combustion engine 10 by an intake manifold.

  In the exhaust passage 10ex, on the downstream side of the turbine 11a, a DPF 14 (Diesel Particulate Filter), a NOx purification device 15, and a DOC 16 (Diesel Oxidation Catalyst) are arranged in this order. The DPF 14 collects fine particles contained in the exhaust. A supply pipe 35 of a highly active substance addition device is connected to the exhaust passage 10ex downstream of the DPF 14 and upstream of the NOx purification device 15. The reforming / reducing agent generated by the highly active substance adding device is added from the supply pipe 35 to the exhaust passage 10ex. The reforming / reducing agent is obtained by partially oxidizing a hydrocarbon (fuel) used as a reducing agent to reform it into a partially oxidized hydrocarbon, which will be described in detail later with reference to FIG.

The NOx purification device 15 includes a honeycomb-shaped carrier 15b that carries a reduction catalyst, and a housing 15a that houses the carrier 15b. The NOx purifying device 15 purifies NOx contained in the exhaust by reacting NOx in the exhaust with the reforming reducing agent on the reduction catalyst and reducing it to N ₂ . The exhaust gas contains O ₂ in addition to NOx, but the reforming / reducing agent reacts selectively with NOx in the presence of O ₂ .

  A reduction catalyst having a function of adsorbing NOx is used. Specifically, when the catalyst temperature is lower than the activation temperature at which the reduction reaction is possible, the reduction catalyst exhibits a function of adsorbing NOx in the exhaust. When the catalyst temperature is equal to or higher than the activation temperature, the adsorbed NOx is reduced by the reforming reducing agent and released from the reduction catalyst. For example, the NOx purification device 15 having a NOx adsorption function is provided by a reduction catalyst made of silver alumina supported on the carrier 15b.

  The DOC 16 is configured by accommodating a carrier carrying an oxidation catalyst in a housing. The DOC 16 oxidizes the reducing agent that has not been used for NOx reduction on the reduction catalyst and has flowed out of the NOx purification device 15 on the oxidation catalyst. This prevents the reducing agent from being released into the atmosphere from the outlet of the exhaust passage 10ex. Note that the activation temperature of the oxidation catalyst (eg, 200 ° C.) is lower than the activation temperature of the reduction catalyst (eg, 250 ° C.).

  Next, a highly active substance adding device that generates a reforming and reducing agent and adds it to the exhaust passage 10ex from the supply pipe 35 will be described. The highly active substance addition apparatus includes a discharge reactor 20, an air pump 31, a fuel injection valve 33, and an electric heater 34, which will be described in detail below. The discharge reactor 20 includes a plurality of pairs of a pair of electrodes 21 that have a ground voltage and a high voltage. Each electrode 21 has a flat plate shape and is disposed so as to face each other in parallel. The voltage application to the electrode 21 is controlled by a microcomputer (microcomputer 81) included in the electronic control unit (ECU 80).

  A case 30 that forms a mixing chamber 30 a is attached to the upstream side of the discharge reactor 20. The air blown by the air pump 31 flows into the mixing chamber 30a through the blow pipe 32. The air pump 31 is driven by an electric motor, and the electric motor is controlled by the microcomputer 81. The air blown by the air pump 31 is a normal temperature and normal pressure atmosphere existing around the highly active substance adding device. Since air contains oxygen molecules, it can be said that the air pump 31 supplies oxygen-containing gas to the mixing chamber 30a. Hereinafter, such a gas containing at least oxygen is simply referred to as oxygen gas. The air pump 31 provides “oxygen supply means” for supplying oxygen gas to the discharge reactor 20.

  The liquid fuel in the fuel tank 33t is supplied to the fuel injection valve 33 by the pump 33p and injected from the injection hole of the fuel injection valve 33 into the mixing chamber 30a. The fuel in the fuel tank 33t is also used as the fuel for combustion described above, and the fuel used for combustion of the internal combustion engine 10 and the fuel used as the reducing agent are shared. The fuel injection valve 33 is structured to open by an electromagnetic force generated by an electromagnetic solenoid, and the energization of the electromagnetic solenoid is controlled by the microcomputer 81. The fuel injection valve 33 provides “hydrocarbon supply means” for supplying hydrocarbons to the discharge reactor 20 by injecting fuel.

  The electric heater 34 is disposed in the mixing chamber 30 a and heats the liquid fuel injected from the fuel injection valve 33. The state of energization to the electric heater 34 is controlled by the microcomputer 81. The liquid fuel heated by the electric heater 34 is vaporized in the mixing chamber 30a, and the vaporized fuel is heated to a predetermined temperature or higher by the electric heater 34. As a result, cracking occurs in which the fuel is decomposed into hydrocarbons having a small number of carbon atoms. Since the hydrocarbon having a reduced number of carbon atoms due to cracking has a low boiling point, the vaporized fuel is suppressed from returning to a liquid.

  In the mixing chamber 30a, the fuel vaporized and cracked by the electric heater 34 and the air containing the oxygen gas supplied by the air pump 31 are mixed. The air-fuel mixture flows through the flow passage 21 a between the electrodes 21 of the discharge reactor 20 and is added to the exhaust passage 10 ex through the supply pipe 35. The discharge reactor 20 oxidizes hydrocarbons contained in the air-fuel mixture to generate a reforming reducing agent. Hereinafter, the production reaction will be described with reference to FIG.

  First, as indicated by reference numeral (1) in FIG. 2, electrons emitted from the electrode 21 collide with oxygen gas (oxygen molecules) contained in the air-fuel mixture. Then, the oxygen molecules are ionized and become active oxygen (see symbol (2)). Next, the active oxygen reacts with the gaseous fuel (hydrocarbon) contained in the air-fuel mixture to partially oxidize the hydrocarbon (see symbol (3)). Thereby, the reforming / reducing agent in a state where the hydrocarbons are partially oxidized is generated (see reference numeral (4)). Specific examples of the reforming / reducing agent include partial oxides in a state in which a part of the hydrocarbon is oxidized to a hydroxy group (OH) or an aldehyde group (CHO).

  Further, the discharge reactor 20 actively generates ozone as shown in FIG. 3 in a state where the fuel injection by the fuel injection valve 33 is stopped and no fuel flows. That is, first, electrons emitted from the electrode 21 collide with oxygen gas (oxygen molecules) blown by the air pump 31 (see reference numeral (1)). Then, the oxygen molecules are ionized and become active oxygen (see symbol (2)). Then, the active oxygen is oxidized by reacting with the oxygen molecules that are blown (see symbol (5)).

  In short, if a voltage is applied to the electrode 21 to activate the air pump 31, the discharge reactor 20 turns oxygen gas into a plasma state by glow discharge and ionizes oxygen molecules into active oxygen. If the fuel is injected in this state, the discharge reactor 20 partially oxidizes the fuel with active oxygen to generate a reforming and reducing agent. On the other hand, if fuel injection is stopped, the discharge reactor 20 generates ozone from oxygen gas by active oxygen. The generated reforming / reducing agent or ozone flows out of the flow passage 21a between the electrodes 21 due to the blowing pressure of the air pump 31, and is added to the exhaust passage 10ex through the supply pipe 35.

  The microcomputer 81 provided in the ECU 80 includes a storage device that stores a program and a central processing unit that executes arithmetic processing according to the stored program. The ECU 80 controls the operation of the internal combustion engine 10 based on detection values of various sensors. Specific examples of the various sensors include an accelerator pedal sensor 91, an engine speed sensor 92, a throttle opening sensor 93, an intake pressure sensor 94, an intake air amount sensor 95, an exhaust temperature sensor 96, and the like.

  The accelerator pedal sensor 91 detects a user's accelerator pedal depression amount. The engine rotation speed sensor 92 detects the rotation speed of the output shaft 10 a of the internal combustion engine 10. The throttle opening sensor 93 detects the opening of the throttle valve 13. The intake pressure sensor 94 detects the pressure on the downstream side of the throttle valve 13 in the intake passage 10in. The intake air amount sensor 95 detects the mass flow rate of intake air.

  In general, the ECU 80 controls the injection amount and injection timing of combustion fuel injected from a fuel injection valve (not shown) according to the rotation speed of the output shaft 10a and the load of the internal combustion engine 10. Further, the ECU 80 controls the operation of the highly active substance adding device based on the exhaust temperature detected by the exhaust temperature sensor 96. That is, the microcomputer 81 performs control so as to switch between the generation of the reforming reducing agent and the generation of ozone by repeatedly executing the program of the procedure shown in FIG. 4 at a predetermined period. The above program is triggered by the ignition switch being turned on, and is always executed during the operation period of the internal combustion engine 10.

  First, in step S10 in FIG. 4, the microcomputer 81 operates the air pump 31. In subsequent step S20, it is determined whether or not the temperature of the reduction catalyst (NOx catalyst temperature) of the NOx purification device 15 is lower than the activation temperature. The NOx catalyst temperature is estimated from the exhaust temperature detected by the exhaust temperature sensor 96. Here, the activation temperature of the reduction catalyst indicates a temperature at which NOx can be reduced and purified by the reforming reducing agent.

  If it is determined that the NOx catalyst temperature is lower than the activation temperature, in step S30, the fuel injection valve 33 is closed to stop fuel injection, and energization to the electric heater 34 is stopped. In subsequent step S <b> 40, discharge is performed by applying a voltage to the electrode 21 to generate ozone in the discharge reactor 20. The microcomputer 81 when executing the processes of steps S30 and S40 provides “ozone generation control means”.

  When it is determined that the NOx catalyst temperature is not lower than the activation temperature, in step S50, the fuel injection valve 33 is opened so that fuel injection is performed, and the electric heater 34 is energized. In subsequent step S <b> 60, discharge by applying voltage to the electrode 21 is performed, and a reforming reducing agent is generated in the discharge reactor 20. The microcomputer 81 at the time of executing the processing of steps S50 and S60 provides “reforming control means”.

  As described above, the highly active substance addition device according to the present embodiment supplies the fuel (hydrocarbon) to the discharge reactor 20 that ionizes the supplied oxygen gas to form active oxygen by discharge. A fuel injection valve 33. And the ozone production | generation control means by FIG.4 S30 and S40 and the reforming control means by step S50 and S60 are provided by the microcomputer 81. FIG. Therefore, if fuel injection is stopped by the ozone generation control means, ozone is generated by active oxygen, and if fuel is injected by the reforming control means, the fuel is oxidized (reformed) by active oxygen and reformed and reduced. An agent is produced. Therefore, both the reforming of the reducing agent and the generation of ozone can be realized with one discharge reactor 20.

  Moreover, since the fuel is oxidized by the active oxygen ionized by the discharge reactor 20 to produce the reforming / reducing agent, the reduction reaction rate is increased compared to the case of reforming the reducing agent with ozone as in Patent Document 1 described above. it can. Therefore, it is possible to suppress the reducing agent from passing through the discharge reactor 20 without being modified, and to increase the amount of the modifying reducing agent that can be added to the exhaust passage 10ex per unit time.

Furthermore, in this embodiment, the reduction catalyst has a function of adsorbing NOx. Therefore, when ozone generated in the discharge reactor 20 is added to the exhaust passage 10ex, NO in the exhaust is oxidized to NO ₂ and is easily adsorbed by the reduction catalyst. Therefore, the generated ozone can be used for improving NOx adsorption on the reduction catalyst.

Further, in the present embodiment, ozone is generated on the condition that the reduction catalyst is lower than the activation temperature, and the reforming reducing agent is generated on the condition that the reduction catalyst is higher than the activation temperature. Therefore, it can be avoided that the reforming reducing agent is added to the exhaust passage 10ex at a low temperature when the reduction catalyst cannot exhibit the reducing ability. And, at the low temperature, ozone is added to the exhaust passage 10ex to oxidize NO to NO ₂ and improve NOx adsorption, so that NOx can be prevented from flowing out of the NOx purification device 15 without being purified at low temperatures.

  Further, although ozone is more likely to be thermally decomposed as the temperature is higher, in the present embodiment, ozone is added to the exhaust passage 10ex when the temperature is low, and is not added except when the temperature is low. Therefore, the possibility that the added ozone is thermally decomposed by exhaust heat can be reduced.

  Here, if the liquid fuel injected from the fuel injection valve 33 adheres to the electrode 21, the timing for supplying the reformed fuel to the exhaust passage 10ex may not be controlled as intended. For example, there is a concern that the supply of the reforming / reducing agent is delayed or the reforming / reducing agent is added unintentionally at a low exhaust temperature. In response to this concern, in the present embodiment, the liquid fuel injected from the fuel injection valve 33 is heated by the electric heater 34. Therefore, the vaporization of the liquid fuel is promoted, the liquid fuel can be prevented from adhering to the electrode 21, and the above concerns can be reduced.

  Furthermore, in this embodiment, since liquid fuel is heated with the electric heater 34, the cracking mentioned above can be produced and the boiling point of fuel can be reduced. Accordingly, it is possible to suppress the vaporized fuel from being cooled by the oxygen gas and returning to the liquid, and thus it is possible to suppress the liquid fuel from adhering to the electrode 21.

  Further, in the present embodiment, the atmosphere is used as an oxygen gas containing at least oxygen, and the atmosphere is supplied to the discharge reactor 20 by the air pump 31. Therefore, for example, oxygen gas having a high oxygen concentration can be supplied to the discharge reactor 20 as compared with the case where the exhaust gas from the internal combustion engine 10 is used as oxygen gas.

(Second Embodiment)
In the present embodiment shown in FIG. 5, when it is determined that the NOx catalyst temperature is lower than the activation temperature and the fuel injection is stopped in step S30, in the subsequent step S35, the NOx catalyst temperature is currently adsorbed by the reduction catalyst. The amount of NOx (NOx adsorption amount) is estimated. For example, the NOx adsorption amount is estimated based on the history of various state values such as the rotational speed of the output shaft 10a, the load of the internal combustion engine 10, the injection amount of fuel used for combustion in the internal combustion engine 10, the NOx catalyst temperature, and the exhaust temperature. . The NOx adsorption amount estimated here corresponds to the “capture amount” described in the claims. Further, the microcomputer 81 when executing the process of step S35 provides “capture amount estimating means”.

  In a succeeding step S36, it is determined whether or not the estimated NOx adsorption amount is less than the saturation amount. If it is determined that the NOx adsorption amount is not less than the saturation amount, energization of the discharge reactor 20 is stopped in the subsequent step S37, and the discharge at the electrode 21 is stopped. On the other hand, if it is determined that the NOx adsorption amount is less than the saturation amount, discharge is performed in step S40, and ozone is generated in the discharge reactor 20.

Now, if the situation in which reduction catalyst can not adsorb saturated, even the NO to add ozone to the exhaust passage 10ex is oxidized to NO _2, is not sufficiently exerted effect of adsorption improvement, wasteful ozone Will be generated. On the other hand, according to the present embodiment, generation of ozone is prohibited when the NOx adsorption amount reaches the saturation amount. Therefore, it is possible to suppress the wasteful generation of ozone, and to reduce wasteful power consumption in the discharge reactor 20.

(Third embodiment)
In this embodiment shown in FIG. 6, when it determines with NOx catalyst temperature not being less than activation temperature in step S20, it progresses to step S21. In this step S21, it is determined whether or not the temperature of the oxidation catalyst (oxidation catalyst temperature) of the DOC 16 is higher than the activation temperature at which hydrocarbons or hydrocarbon partial oxides can be oxidized and purified. The oxidation catalyst temperature is estimated from the exhaust temperature detected by the exhaust temperature sensor 96. If it is determined that the oxidation catalyst temperature is not higher than the activation temperature, the fuel injection is stopped in step S30, and ozone is generated in step S40. On the other hand, if it is determined that the oxidation catalyst temperature is higher than the activation temperature, fuel injection is performed in step S50, and a reforming / reducing agent is generated in step S60.

  As described above, according to the present embodiment, when the oxidation catalyst is lower than the activation temperature, the generation of the reforming reducing agent by fuel injection is prohibited regardless of the temperature of the reduction catalyst. Therefore, prevention of the reducing agent flowing out from the NOx purification device 15 from being released into the atmosphere from the exhaust passage 10ex without being oxidized by the DOC 16 can be promoted.

(Fourth embodiment)
In the first embodiment shown in FIG. 1, an air pump 31 that blows air is used as an oxygen supply unit that supplies oxygen gas to the discharge reactor 20. On the other hand, in the present embodiment shown in FIG. 7, a part of the intake air of the internal combustion engine 10 is branched and flows into the discharge reactor 20.

  Specifically, the downstream portion of the compressor 11c and the upstream portion of the cooler 12 in the intake passage 10in and the mixing chamber 30a of the highly active substance adding device are connected by a branch pipe 36. An electromagnetic valve 31A for opening and closing the internal passage is attached to the branch pipe 36. The operation of the electromagnetic valve 31A is controlled by the microcomputer 81. When the electromagnetic valve 31A opens, a part of the intake air compressed by the compressor 11c branches from the intake passage 10in to the branch pipe 36 and flows into the mixing chamber 30a. Since oxygen molecules are contained in the intake air, it can be said that the branch pipe 36 supplies oxygen-containing gas (oxygen gas) to the mixing chamber 30a. That is, the branch pipe 36 provides “oxygen supply means” for supplying oxygen gas to the discharge reactor 20.

  During the period in which the electromagnetic valve 31A is opened, the amount of intake air flowing into the combustion chamber of the internal combustion engine 10 is reduced by the amount that a portion of the intake air branches and flows through the branch pipe 36. Therefore, the microcomputer 81 corrects the opening degree of the throttle valve 13 so that the intake air amount is increased by the amount flowing into the branch pipe 36 during the valve opening period of the electromagnetic valve 31A.

  As described above, according to the present embodiment, a part of the intake air supercharged by the supercharger 11 is supplied to the discharge reactor 20. Therefore, it is possible to supply oxygen gas to the discharge reactor 20 and add it to the exhaust passage 10ex through the supply pipe 35 without using the air pump 31 shown in FIG.

(Fifth embodiment)
In the fourth embodiment shown in FIG. 7, the branch pipe 36 is connected to the upstream portion of the cooler 12 in the intake passage 10in located on the downstream side of the compressor 11c. On the other hand, in the present embodiment shown in FIG. 8, in addition to connecting the branch pipe 36 to the upstream portion of the cooler 12 in the intake passage 10in, the branch pipe (second branch pipe) is also connected to the downstream portion of the cooler 12. 37) is connected. The branch pipe 36 supplies the high-temperature intake air before being cooled by the cooler 12 to the mixing chamber 30a. The second branch pipe 37 supplies the low temperature intake air after being cooled by the cooler 12 to the mixing chamber 30a.

  An electromagnetic valve 31B that opens and closes the internal passage is attached to the branch pipe 36 and the second branch pipe 37. The operation of the electromagnetic valve 31B is controlled by the microcomputer 81. When the electromagnetic valve 31B is operated so as to open the branch pipe 36 and close the second branch pipe 37, the high-temperature intake air flows into the mixing chamber 30a. When the electromagnetic valve 31B is operated so as to open the second branch pipe 37 and close the branch pipe 36, the low temperature intake air flows into the mixing chamber 30a. The branch pipe 36 and the second branch pipe 37 provide “oxygen supply means” for supplying a gas containing at least oxygen (oxygen gas) to the discharge reactor 20.

  In the present embodiment shown in FIG. 9, the following steps S25 and S26 are added to the processing procedure of FIG. 4, and the processing of step S10 is abolished. That is, first, in step S20 of FIG. 9, it is determined whether or not the NOx catalyst temperature is lower than the activation temperature.

  When it is determined that the NOx catalyst temperature is lower than the activation temperature, the low temperature intake air is introduced from the second branch pipe 37 and the introduction of the high temperature intake air from the branch pipe 36 is stopped in the subsequent step S25. Thus, the electromagnetic valve 31B is operated. Thereafter, in step S30, fuel injection is stopped and energization to the electric heater 34 is stopped. In the subsequent step S40, discharge is performed, and ozone is generated by the low temperature intake air from the second branch pipe 37.

  On the other hand, when it is determined that the NOx catalyst temperature is not lower than the activation temperature, in the subsequent step S26, the high temperature intake air is introduced from the branch pipe 36 and the introduction of the low temperature intake air from the second branch pipe 37 is stopped. Thus, the electromagnetic valve 31B is operated. Thereafter, in step S50, fuel is injected and the electric heater 34 is energized. In subsequent step S60, discharge is performed, and the reforming / reducing agent is generated by the high temperature intake air from the branch pipe 36.

  As described above, according to the present embodiment, the branch pipe 36 and the second pipe are supplied so that the intake air is supplied from the downstream side of the cooler 12 when ozone is generated and from the upstream side of the cooler 12 when the reforming / reducing agent is generated. The open state of the branch pipe 37 is switched.

  Therefore, at the time of ozone generation, the low-temperature intake air cooled by the cooler 12 is supplied as oxygen gas, so that the generated ozone can be prevented from being destroyed by the heat of the intake air. In addition, when the reforming / reducing agent is generated, the intake air whose temperature has increased due to the compression of the compressor 11c and before being cooled by the cooler 12 is supplied as oxygen gas. Therefore, it is possible to suppress the fuel heated by the electric heater 34 from being cooled by the intake air in the mixing chamber 30a. Therefore, it is possible to prevent the fuel supplied to the discharge reactor 20 from being liquefied by cooling and attached to the electrode 21.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as illustrated below. Not only combinations of parts that clearly show that combinations are possible in each embodiment, but also combinations of the embodiments even if they are not explicitly stated unless there is a problem with the combination. Is also possible.

  In the case of a complete stop where both the generation of ozone and the generation of the reforming reducing agent are stopped, the supply of oxygen gas may be stopped. That is, in the case of the embodiment shown in FIG. 1, the operation of the air pump 31 may be stopped during the complete stop to reduce power consumption. Further, in the case of the embodiment shown in FIGS. 7 and 8, the accuracy of setting the intake air amount drawn into the combustion chamber to the target amount by closing the electromagnetic valves 31A and 31B and stopping the branching of the intake air. Improvements may be made. Specific examples of the case of complete stop include a case where the NOx catalyst temperature is lower than the activation temperature and the NOx adsorption amount is saturated, or the NOx catalyst temperature exceeds the reducible range and becomes high. There are cases.

  In the above embodiment shown in FIG. 1, a reduction catalyst that physically captures (that is, adsorbs) NOx is employed. However, the combustion system employs a reduction catalyst that traps (that is, stores) NOx by chemical bonding. Alternatively, a highly active substance addition apparatus may be applied.

  When the internal combustion engine 10 is burned in a state leaner than the stoichiometric air-fuel ratio, the highly active substance addition device is applied to a combustion system in which the NOx purification device 15 adsorbs NOx and reduces NOx in other than lean combustion. May be. In this case, ozone may be generated at the time of lean combustion, and a reforming reducing agent may be generated at times other than lean combustion. As a specific example of the catalyst that captures NOx during lean combustion in this way, an occlusion reduction catalyst using platinum and barium supported on a carrier can be cited.

The highly active substance addition device may be applied to a combustion system in which the NOx purification device 15 that does not have an adsorption or storage function is employed. In this case, ozone generated in the discharge reactor 20 may be used for regeneration of the DPF 14. That is, by adding ozone upstream of the DPF 14, NO in the exhaust is oxidized to NO ₂ and flows into the DPF 14. Then, the carbon component of the fine particles collected and deposited by the DPF 14 reacts with NO ₂ and is oxidized. Thereby, the fine particles deposited on the DPF 14 are removed, and the DPF 14 is regenerated.

  In the embodiment shown in FIG. 1, the liquid fuel is atomized by injecting the fuel from the injection hole of the fuel injection valve 33 while reducing the pressure. Specifically, the liquid fuel is ejected with a particle size of 60 μm or less. On the other hand, the fuel injection valve 33 may be replaced with an electromagnetic valve so that fuel flows into the mixing chamber 30a without atomization. In the embodiment shown in FIG. 1, the fuel is heated by the electric heater 34, but the electric heater 34 may be omitted.

  In the first embodiment, the NOx catalyst temperature used in step S <b> 20 of FIG. 4 is estimated from the exhaust temperature detected by the exhaust temperature sensor 96. On the other hand, a temperature sensor may be attached to the NOx purification device 15 to directly measure the NOx catalyst temperature. Alternatively, the NOx catalyst temperature may be estimated based on the rotation speed of the output shaft 10a, the load of the internal combustion engine 10, and the like.

  In the embodiment shown in FIG. 1, the discharge reactor 20 is configured by arranging flat-plate electrodes 21 so as to face each other in parallel. On the other hand, the discharge reactor may be constituted by a needle-like electrode protruding in a needle shape and an annular electrode surrounding the needle-like electrode in an annular shape.

  In the embodiment shown in FIG. 1, the electric heater 34 is employed as a heating means for heating and vaporizing liquid hydrocarbons, but a heat exchanger using waste heat of the internal combustion engine 10 is employed as the heating means. Also good. Alternatively, the means for heating the fuel may be eliminated. In the embodiment shown in FIG. 1, the liquid fuel is supplied from the fuel injection valve 33 to the mixing chamber 30a. However, the liquid fuel is heated and vaporized outside the mixing chamber 30a, and the gaseous fuel is mixed into the mixing chamber 30a. You may make it supply to 30a.

  In the embodiment shown in FIG. 1, the discharge reactor 20 is installed so that the plate-like electrode 21 is in a horizontal orientation in a vehicle-mounted state. On the other hand, the liquid fuel attached to the electrode 21 may be easily dropped by gravity by installing the plate-shaped electrode 21 so that the plate surface is inclined with respect to the horizontal direction. Moreover, you may install so that the plate | board surface of the plate-shaped electrode 21 may become the direction parallel to the up-down direction.

  In the embodiment shown in FIG. 1, the fuel injection valve 33 is employed as the atomizing means for atomizing liquid hydrocarbons and supplying them to the heating means. On the other hand, a vibrating device that vibrates the liquid fuel and makes it atomize by bringing the liquid fuel into contact with a vibration plate that vibrates at a high frequency such as ultrasonic waves may be employed as the atomizing means.

  In the embodiment shown in FIG. 1, a highly active substance addition device is applied to a combustion system mounted on a vehicle. On the other hand, a highly active substance addition device may be applied to a stationary combustion system. In the embodiment shown in FIG. 1, a highly active substance addition device is applied to a compression self-ignition diesel engine, and light oil used as a fuel for combustion is used as a reducing agent. On the other hand, gasoline used as a fuel for combustion may be used as a reducing agent by applying a highly active substance addition device to an ignition ignition type gasoline engine.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 10ex ... Exhaust passage, 15 ... NOx purification apparatus, 20 ... Discharge reactor, 31 ... Air pump (oxygen supply means), 33 ... Fuel injection valve (hydrocarbon supply means), S30, S40 ... Ozone production control means , S50, S60 ... reforming control means.

Claims (7)

A NOx purification device (15) for purifying NOx contained in the exhaust gas of the internal combustion engine (10) on the reduction catalyst is provided in a combustion system provided in the exhaust passage (10ex), and upstream of the reduction catalyst in the exhaust passage. In the highly active substance addition device for adding a highly active substance from the supply pipe (35) connected to the side to the exhaust passage,
A discharge reactor (20) disposed outside the exhaust passage and ionizing oxygen gas by discharge;
Hydrocarbon supply means (33) for supplying hydrocarbons to the discharge reactor;
Ozone generation control means (S30, S40) for generating ozone as the highly active substance from the oxygen gas ionized by the discharge reactor by controlling the hydrocarbon supply means so as to stop the supply of the hydrocarbon; ,
By controlling the hydrocarbon supply means so as to supply the hydrocarbon, the hydrocarbon is oxidized with the oxygen gas ionized by the discharge reactor to generate a reforming reducing agent as the highly active substance. Reforming control means (S50, S60);
Oxygen supply means (31, 36, 37) for supplying intake air or air of the internal combustion engine to the discharge reactor as oxygen gas containing at least oxygen;
Equipped with a,
The combustion system includes a supercharger (11) for supercharging intake air of the internal combustion engine, and a cooler (12) for cooling intake air supercharged by the supercharger,
The oxygen supply means (36, 37)
While supplying a part of the intake air supercharged by the supercharger to the discharge reactor,
At the time of ozone generation by the ozone generation control means, the intake air on the downstream side of the cooler is supplied to the discharge reactor, and at the time of generation of the reforming reducing agent by the reforming control means, the intake air on the upstream side of the cooler is discharged. highly active materials added and wherein that you fed to the reactor. A NOx purification device (15) for purifying NOx contained in the exhaust gas of the internal combustion engine (10) on the reduction catalyst is provided in a combustion system provided in the exhaust passage (10ex), and upstream of the reduction catalyst in the exhaust passage. In a highly active substance addition device that adds a highly active substance to the side,
A discharge reactor (20) for ionizing oxygen gas by discharge;
Hydrocarbon supply means (33) for supplying hydrocarbons to the discharge reactor;
Ozone generation control means (S30, S40) for generating ozone as the highly active substance from the oxygen gas ionized by the discharge reactor by controlling the hydrocarbon supply means so as to stop the supply of the hydrocarbon; ,
By controlling the hydrocarbon supply means so as to supply the hydrocarbon, the hydrocarbon is oxidized with the oxygen gas ionized by the discharge reactor to generate a reforming reducing agent as the highly active substance. Reforming control means (S50, S60);
Oxygen supply means (31, 36, 37) for supplying intake air or air of the internal combustion engine to the discharge reactor as oxygen gas containing at least oxygen;
With
The combustion system includes a supercharger (11) for supercharging intake air of the internal combustion engine, and a cooler (12) for cooling intake air supercharged by the supercharger,
The oxygen supply means (36, 37)
While supplying a part of the intake air supercharged by the supercharger to the discharge reactor,
At the time of ozone generation by the ozone generation control means, the intake air on the downstream side of the cooler is supplied to the discharge reactor, and at the time of generation of the reforming reducing agent by the reforming control means, the intake air on the upstream side of the cooler is discharged. A highly active substance adding device characterized by being supplied to a reactor. The highly active substance addition device according to claim 1 or 2 , wherein the reduction catalyst has a function of adsorbing or storing NOx. The ozone generation control means generates ozone on the condition that the reduction catalyst is lower than the activation temperature,
4. The highly active substance adding device according to claim 3 , wherein the reforming control means generates a reforming reducing agent on condition that the reduction catalyst is at an activation temperature or higher. A trapping amount estimating means (S35) for estimating the trapping amount of NOx adsorbed or occluded by the reduction catalyst;
The highly active substance according to claim 3 or 4 , wherein when the trapped amount estimated by the trapped amount estimating means reaches a saturation amount, generation of ozone by the ozone generation control means is prohibited. Addition equipment. A reducing agent purification device (16) for purifying the reducing agent flowing out from the NOx purification device on the oxidation catalyst is disposed on the downstream side of the reduction catalyst in the exhaust passage,
Wherein when the oxidation catalyst is lower than the activation temperature, the irrespective of the temperature of the reduction catalyst, claim 1-5, characterized in that prohibiting generation of the reformed reducing agent by the reforming control unit The highly active substance addition apparatus as described in one. The highly active substance according to any one of claims 1 to 6 , further comprising an electric heater (34) that is disposed upstream of the discharge reactor and that heats hydrocarbons supplied to the discharge reactor. Addition equipment.

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