JP2015129505A - High active material addition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable modification of a reducer while suppressing deposition of deposits.SOLUTION: A high active material addition device for adding a reducer to upstream of a NOx purifier 15 in an exhaust passage 10ex of an internal combustion engine 10 comprises: a fuel injection valve 33; an electric heater 34; a modification control means; and cleaning control means. A fuel supplied from the fuel injection valve 33 to a vaporization chamber 36a is heated and vaporized by the electric heater 34. During modification control, a modified reducer is produced. During cleaning control, the electric heater 34 is actuated while stopping supply of the fuel and air (oxygen gas) is supplied into the vaporization chamber 36a, thereby firing and removing fuel components deposited in the vaporization chamber 36a without being vaporized.

Description

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

  2. Description of the Related Art Conventionally, a technique for purifying NOx (nitrogen oxide) contained in exhaust gas of an internal combustion engine by reacting with a reducing agent on a catalyst is known. With regard to this technique, the highly active substance addition device described in Patent Document 1 uses a fuel (hydrocarbon) used for combustion of an internal combustion engine as a reducing agent. Then, the liquid fuel is sprayed into the fuel passage to be reformed, and the reformed liquid fuel is added to the exhaust passage.

JP 2009-162173 A

  However, in the above-described conventional apparatus, the following problems occur due to the mist-like liquid fuel adhering to the fuel passage or the like. That is, the liquid fuel adhering to the fuel passage or the like remains adhering until it is vaporized, and the timing at which it is vaporized and discharged from the adhering location becomes uncertain. Therefore, it becomes difficult to add the reducing agent to the exhaust passage at a desired timing.

  In order to solve this problem, the present inventors have studied a configuration in which a vaporization chamber for heating and vaporizing liquid fuel is provided and gas fuel is supplied to a fuel passage or the like. However, with this configuration, a new problem arises in that a part of the heavy components contained in the fuel undergoes a polymerization reaction in the vaporization chamber to generate solids, and the solids accumulate in the vaporization chamber as deposits. .

  When such deposits are deposited, the gas fuel outlet formed in the vaporizing chamber is blocked, and the deposit adheres to the heater, which deteriorates the heat transfer from the heater to the liquid fuel. This causes a problem that the rapid vaporization of the liquid fuel is hindered.

  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 adding device that can modify a reducing agent while suppressing deposit accumulation.

  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 the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of the invention. .

  One of the disclosed inventions is a highly active substance adding device. This highly active substance addition device is provided in a combustion system in which an NOx purification device (15) for purifying NOx contained in exhaust gas of an internal combustion engine (10) on a reduction catalyst is provided in an exhaust passage (10ex). It is assumed that a highly active substance is added upstream of the reduction catalyst. The highly active substance addition apparatus includes a hydrocarbon supply means (33) for supplying liquid hydrocarbons to the vaporization chamber (36a) and a heating means for heating and vaporizing the liquid hydrocarbons supplied to the vaporization chamber. (34), and by operating the hydrocarbon supply means and the heating means, the operation of the reforming control means (S25, S26) for generating the reforming and reducing agent as the highly active substance and the hydrocarbon supply means are stopped. Cleaning control means (S60) for operating the heating means and causing air to flow into the vaporizing chamber to burn and remove components deposited in the vaporizing chamber without being vaporized out of liquid hydrocarbons, It is characterized by providing.

  According to the present invention, since the heating means for heating and vaporizing the liquid hydrocarbon is provided, the reforming / reducing agent is controlled by the reforming control means while suppressing the problem that the liquid hydrocarbon adheres to various passages and the like. Can be generated. Nevertheless, components (deposits) that are not vaporized and are deposited in the vaporizing chamber without being vaporized can be burned and removed under the control of the cleaning control means. That is, it is possible to suppress new problems such as deposit accumulation caused by providing the heating means.

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. Sectional drawing which shows typically the highly active substance addition apparatus shown in FIG. Sectional drawing which follows the III-III line | wire in FIG. Sectional drawing which follows the IV-IV line in FIG. The schematic diagram explaining the mechanism in which reformed HC is generated in a 1st embodiment. The schematic diagram explaining the mechanism by which ozone is produced | generated in 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 process sequence which controls fuel supply amount and heater temperature in 1st Embodiment. 5 is a flowchart illustrating a processing procedure for setting a timing for performing cleaning in the first embodiment. 6 is a flowchart illustrating a cleaning control processing procedure in the first embodiment. Sectional drawing which shows typically the highly active substance addition apparatus which concerns on 2nd Embodiment of this invention. 9 is a flowchart showing a cleaning control processing procedure in the second embodiment. Sectional drawing which shows typically the highly active substance addition apparatus which concerns on 3rd Embodiment of this invention.

  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.

  The exhaust discharged from the plurality of combustion chambers is collected by the exhaust manifold 10m. The exhaust manifold 10m is provided with a return pipe 10egr for returning a part of the exhaust gas to the intake passage 10in as EGR (Exhaust Gas Recirculation) gas. By mixing EGR gas into the intake air in this way, the combustion temperature in the combustion chamber is lowered and NOx reduction is achieved. An EGR cooler 17 and an EGR valve 18 are attached to the reflux pipe 10 egr. The EGR cooler 17 further reduces the combustion temperature by cooling the EGR gas and promotes NOx reduction. The EGR valve 18 is controlled by the ECU 80 and controls the flow rate of the EGR gas according to the operating state of the internal combustion engine 10.

  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 24 of a highly active substance addition device is connected to the exhaust passage 10ex on the downstream side of the DPF 14 and the upstream side of the NOx purification device 15. The reforming / reducing agent generated by the highly active substance adding device is added from the supply pipe 24 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 24 will be described with reference to FIGS.

  The highly active substance addition device is disposed outside the exhaust passage 10ex, and will be described in detail below, including a discharge reactor 20, a fuel injection valve 33, an electric heater 34, a high temperature intake pipe 10h, a low temperature intake pipe 10c, and a heat exchanger 10a. And an electronic control unit (ECU 80). Energization of the discharge reactor 20, the fuel injection valve 33, and the electric heater 34 is controlled by a microcomputer (microcomputer 81) provided in the ECU 80.

  The discharge reactor 20 includes a housing 22 that forms a flow passage 22a therein, and a plurality of electrodes 21 are disposed in the flow passage 22a. These electrodes 21 have a flat plate shape arranged so as to face each other in parallel, and electrodes to which a high voltage is applied and electrodes having a ground voltage are alternately arranged.

  A connecting member 30 is attached to the upstream side of the discharge reactor 20, and a cylindrical mixing container 31 that forms a mixing chamber 31 a is disposed in the internal space 30 a of the connecting member 30. The downstream opening of the mixing container 31 has a rectangular shape and is connected to a flow passage 22 a formed by the housing 22. The upstream opening of the mixing container 31 has the same rectangular shape as the opening of the cylindrical member 30b provided in the connecting member 30, and the upstream opening of the mixing container 31 and the opening of the cylindrical member 30b are opposite.

  Therefore, the mixing chamber 31a and the internal space 30a communicate with each other through the gap CL formed between the mixing container 31 and the cylindrical member 30b. Specifically, an internal space 30a exists around the mixing chamber 31a communicating with the flow passage 22a. And it is comprised so that the air of the internal space 30a may flow into the mixing chamber 31a through the annular clearance CL, and sequentially flow into the flow passage 22a and the supply pipe 24.

  A holding member 35 that holds a vaporization case 36, a fuel injection valve 33, an electric heater 34, and a temperature sensor 37, which will be described in detail later, is attached to the upstream side of the connecting member 30. A first air passage 35 a is formed in a lower portion of the holding member 35. On the other hand, a second air passage 30c is formed in the lower part of the connecting member 30, the downstream end of the second air passage 30c communicates with the internal space 30a, and the upstream end of the second air passage 30c is the first air passage. It communicates with 35a. Connected to the holding member 35 is an air pipe 32 through which air introduced from the high temperature intake pipe 10h or the low temperature intake pipe 10c flows to the first air passage 35a.

  As described above, the air introduced from the high temperature intake pipe 10h or the low temperature intake pipe 10c into the air pipe 32 flows through the first air passage 35a, the second air passage 30c, the internal space 30a, and the gap CL in order and flows into the mixing chamber 31a. To do. An “air passage” that guides air used as oxygen gas to the mixing chamber 31a is provided by the first air passage 35a, the second air passage 30c, and the internal space 30a.

  The high temperature intake pipe 10h and the low temperature intake pipe 10c branch a part of the intake air compressed by the compressor 11c from the intake passage 10in and introduce it into the air pipe 32. The high temperature intake pipe 10h branches the high temperature intake air before being cooled by the cooler 12 from the upstream portion of the cooler 12 in the intake passage 10in. The low-temperature intake pipe 10c branches the low-temperature intake air after being cooled by the cooler 12 from the downstream portion of the cooler 12 in the intake passage 10in. These high-temperature intake air or low-temperature intake air contains oxygen molecules. Hereinafter, a gas containing at least oxygen as described above is simply referred to as oxygen gas.

  As shown in FIG. 1, a heat exchanger 10a is attached to the high temperature intake pipe 10h. The heat exchanger 10a exchanges heat between the high-temperature EGR gas flowing through the reflux pipe 10egr and the high-temperature intake air flowing through the heat exchanger 10a. Therefore, the high temperature intake air is heated by the EGR gas. That is, the heat exchanger 10 a provides “oxygen gas heating means” for heating the oxygen gas supplied to the discharge reactor 20.

  The low temperature intake pipe 10c and the high temperature intake pipe 10h are connected to the air pipe 32 through the switching valve 32a. The switching valve 32a is controlled and driven by the microcomputer 81 so that one of the low temperature intake pipe 10c and the high temperature intake pipe 10h communicates with the air pipe 32.

  The vaporizing case 36 forms a vaporizing chamber 36a having a circular cross section inside (see FIGS. 3 and 4). The vaporizing chamber 36a is provided with a heating surface 34a of the electric heater 34 that extends in a rod shape along the axial direction of the vaporizing chamber 36a (the left-right direction in FIG. 2). Moreover, the detection part 37a of the temperature sensor 37 is arrange | positioned above the heating surface 34a among the vaporization chambers 36a, and the temperature sensor 37 changes the temperature of the upper part of the heating surface 34a among the vaporization chambers 36a to an electric heater. 34 as an actual heating degree.

  An opening 36c is formed in the upper part of the peripheral wall of the vaporizing case 36, and the fuel injection valve 33 is disposed above the opening 36c. The mist-like liquid fuel injected from the injection hole 33a (see FIG. 4) of the fuel injection valve 33 flows into the vaporizing chamber 36a through the opening 36c and is sprayed onto the heating surface 34a.

  The liquid fuel that has flowed into the vaporizing chamber 36a is heated by the electric heater 34 and vaporized. Further, the heating surface 34a further heats the vaporized fuel, thereby generating cracking that decomposes the fuel into hydrocarbons having a small number of carbon atoms. For example, the microcomputer 81 controls energization of the electric heater 34 so that the fuel is heated to a temperature at which light oil is cracked (350 ° C. to 500 ° C.). Cracked fuel has a low boiling point and is difficult to condense.

  The fuel that has been vaporized and cracked is ejected from a plurality of ejection ports 36 b formed at the tip of the vaporizing case 36 in the axial direction. The gaseous fuel ejected from the ejection port 36 b is mixed with the air (oxygen gas) introduced through the air pipe 32 or the like in the mixing chamber 31 a and then flows into the discharge reactor 20. A “hydrocarbon outlet” through which hydrocarbon, which is the vaporized fuel, flows out from the vaporization chamber 36a to the discharge reactor 20 is provided by the jet outlet 36b.

  The fuel injection valve 33, the electric heater 34, and the temperature sensor 37 are attached to the vaporizing case 36 through a sealing material (not shown). Therefore, a portion of the vaporizing chamber 36a excluding the air inlet 36d and the jet outlet 36b is a sealed space. Therefore, if the fuel is vaporized during the reforming control, the vaporizing chamber 36a becomes a high pressure.

  The liquid fuel in the fuel tank 33t is supplied to the fuel injection valve 33 by the pump 33p, and is supplied from the injection hole 33a of the fuel injection valve 33 to the vaporization chamber 36a in the atomized state by reducing the pressure. Is done. That is, the fuel injection valve 33 provides “hydrocarbon supply means” for supplying liquid hydrocarbons to the vaporization chamber 36a, and also provides “atomization means” for atomizing the liquid fuel. The fuel is sprayed with a particle size of 60 μm or less.

  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.

  When the amount of liquid fuel injected into the vaporization case 36 per unit time is greater than the amount of vaporization vaporized per unit time, the liquid fuel is stored in the vaporization case 36. In this case, the vaporizing case 36 provides a storage tank that temporarily stores the injected liquid fuel until it is vaporized. However, the fuel injection amount from the injection hole 33a is controlled so that the liquid level of the stored fuel does not reach the lowermost end 36e of the opening 36c.

  The holding member 35 is formed with a branch passage that branches off from the first air passage 35a. This branch passage includes a first branch passage 35b, a second branch passage 35c, and a third branch passage 35d. The first branch passage 35b branches from the first air passage 35a and extends in the vertical direction (see FIG. 2). The second branch passage 35c extends horizontally from the upper end of the first branch passage 35b along the bottom surface of the vaporizing case 36 (see FIGS. 2 and 3). The third branch passage 35d extends upward along the outer peripheral surface of the vaporization case 36 from the downstream end of the second branch passage 35c (see FIGS. 2 and 4).

  As shown in FIG. 4, the upper end (downstream end) of the third branch passage 35 d communicates with the opening 36 c of the vaporizing case 36. Therefore, the portion of the opening 36c that communicates with the third branch passage 35d corresponds to the air inlet 36d. Moreover, the end surface which forms the opening part 36c among the surrounding walls of the vaporization case 36 corresponds to the lowest end part 36e of the air inflow port 36d. And the air inflow port 36d is located below the jet nozzle 36b. More specifically, the lowermost end portion 36e of the air inlet 36d is positioned below the lowermost end portion of the inlet of the jet port 36b.

  The air inflow port 36d is disposed outside the range that is injected from the injection hole 33a of the fuel injection valve 33. This injection range is a range surrounded by two dotted lines extending from the injection hole 33a in FIG. 2 in the heating surface 34a. In short, the air inlet 36d is located at a position shifted from the position directly above the first branch passage 35b to the left side in FIG.

  The second air passage 30c is provided with a throttle portion 30d that reduces the air flow rate. Therefore, the pressure in the internal space 30a becomes lower than the pressure in the first air passage 35a, and the pressure in the mixing chamber 31a decreases. Since the jet port 36b is located in the mixing chamber 31a, when the pressure in the mixing chamber 31a decreases, the gaseous fuel in the vaporizing chamber 36a is easily jetted from the jet port 36b.

  The air-fuel mixture obtained by mixing gaseous fuel and air in the mixing chamber 31 a flows through the interelectrode 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 24. The discharge reactor 20 oxidizes fuel (hydrocarbon) contained in the air-fuel mixture to generate a reforming / reducing agent. Hereinafter, the formation reaction will be described with reference to FIG.

  First, as indicated by reference numeral (1) in FIG. 5, 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. 6 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 the introduced oxygen gas (oxygen molecules) (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, when a voltage is applied to the electrode 21 to introduce oxygen gas, the discharge reactor 20 turns the oxygen gas into a plasma state by glow discharge and ionizes oxygen molecules into active oxygen. If fuel is ejected from the ejection port 36b in this state, the discharge reactor 20 partially oxidizes the fuel with active oxygen to generate a reforming reducing agent. On the other hand, if fuel ejection from the ejection port 36b 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 interelectrode passage 21a between the electrodes 21 due to the supply pressure of oxygen gas, that is, the pressure of the compressor 11c, and is added to the exhaust passage 10ex through the supply pipe 24.

  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 (not shown), an engine speed sensor (not shown), a throttle opening sensor (not shown), an intake pressure sensor (not shown), and an intake air amount sensor 95. Exhaust temperature sensor 96 etc. are mentioned.

  The accelerator pedal sensor detects a user's accelerator pedal depression amount. The engine rotation speed sensor detects the rotation speed of the output shaft of the internal combustion engine 10. The throttle opening sensor detects the opening of the throttle valve 13. The intake pressure sensor 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 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 that the generation of the reforming / reducing agent and the generation of ozone are switched by repeatedly executing the program of the procedure shown in FIGS. 7 and 8 at a predetermined period. These programs are triggered by the ignition switch being turned on as a trigger, and are always executed during the operation period of the internal combustion engine 10.

  First, in step S <b> 11 of FIG. 7, a voltage is applied to the electrode 21 to discharge in the discharge reactor 20. In subsequent step S12, 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, the ozone generation flag is set to ON in step S13. This ozone generation flag instructs to generate ozone as shown in FIG. On the other hand, if it is determined that the NOx catalyst temperature is not lower than the activation temperature, the reforming flag is set to ON in step S14. This reforming flag instructs to generate a reforming reducing agent as shown in FIG.

  If the ozone generation flag is set to ON in step S13, the switching valve 32a is operated so that the low-temperature intake air is supplied from the low-temperature intake pipe 10c to the discharge reactor 20 in the subsequent step S15. On the other hand, when the reforming flag is set to ON in step S14, the switching valve 32a is operated so as to supply the high temperature intake air from the high temperature intake pipe 10h to the discharge reactor 20 in the subsequent step S16. The microcomputer 81 at the time of executing the processes of steps S15 and S16 provides “switching control means”.

  Next, in step S20 of FIG. 8, it is determined whether or not the reforming flag is set to ON. If it is determined that the reforming flag is not on, energization of the electric heater 34 is stopped in the subsequent step S21, and the fuel injection valve 33 is closed so as to stop the fuel injection in step S22. The microcomputer 81 at the time of executing the process of step S22 provides “ozone generation control means”.

  On the other hand, if it is determined that the reforming flag is on, in the subsequent step S23, the amount of reforming reducing agent (necessary reducing agent amount) required by the NOx purification device 15 per unit time is calculated. The microcomputer 81 at the time of executing the process of step S23 provides “necessary amount calculation means”. Hereinafter, a specific example of calculating the necessary reducing agent amount will be described.

  First, the NOx concentration in the exhaust gas and the exhaust amount are calculated based on the operation state of the internal combustion engine 10 such as the load of the internal combustion engine 10, the rotational speed of the output shaft, and the amount of fuel injected for combustion. Next, the NOx amount (NOx emission amount) in the exhaust gas is calculated based on the calculated NOx concentration and the exhaust gas amount. Next, the amount of NOx adsorbed by the NOx purification device 15 (NOx adsorption amount) is calculated based on the calculated NOx emission amount, the supplied amount of reforming / reducing agent, NOx catalyst temperature, and the like. Next, the total NOx amount is calculated by adding the current NOx emission amount to the calculated NOx adsorption amount. Next, the amount of reforming / reducing agent necessary to purify the total NOx amount is calculated as the necessary reducing agent amount.

  After calculating the required reducing agent amount in step S23 as described above, in the subsequent step S24, the target heater temperature is calculated based on the calculated required reducing agent amount. Specifically, the target heater temperature is set higher as the required amount of reducing agent is larger. However, the lower limit value of the target heater temperature is set to be equal to or higher than the crackable temperature.

  In the subsequent step S25, the power supplied to the electric heater 34 is controlled so as to reach the target heater temperature. For example, the supply power is controlled by duty-controlling the pulse width of the voltage applied to the electric heater 34. When the fuel is vaporized, heat is removed from the heating surface 34a due to the latent heat of vaporization. Therefore, electric power is supplied to the electric heater 34 so as to reach the target heater temperature in consideration of the temperature decrease due to the latent heat of vaporization. In the subsequent step S26, the fuel injection is performed by controlling the valve opening time of the fuel injection valve 33 so that the fuel injection amount per unit time becomes the required reducing agent amount. The microcomputer 81 when executing the process of step S26 provides “reforming control means”.

  Now, the liquid fuel injected from the fuel injection valve 33 includes various components such as light fuel and heavy fuel. Light fuel vaporizes rapidly when heated, whereas heavy fuel undergoes a polymerization reaction when heated to produce solids, which deposit as deposits in the vaporization chamber 36a. Therefore, when the above-described reforming control means and ozone generation control means are not executed, the cleaning control described below is executed to periodically remove deposits.

  That is, the microcomputer 81 executes cleaning control by controlling the operation of the fuel injection valve 33 and the electric heater 34 by repeatedly executing the program of the procedure shown in FIG. 9 at a predetermined cycle. These programs are started when the ignition switch is turned on as a trigger, and are always executed even during the operation stop period of the internal combustion engine 10.

  First, in step S30 of FIG. 9, the operation time of the electric heater 34 since the previous cleaning is calculated. In subsequent step S40, it is determined whether or not the heater operation time calculated in step S30 has passed a predetermined time (for example, 20 hours). If it is determined that the predetermined time has not elapsed, the heater operation time is accumulated in step S30. If it is determined that the predetermined time has elapsed, it is determined in the subsequent step S50 whether or not the permission state satisfies the cleaning control execution condition.

  The permitted state is a state in which NOx is not discharged from the internal combustion engine 10 and purification by the NOx purification device 15 is not requested. Specifically, an idle stop state in which the internal combustion engine 10 is automatically stopped, a fuel cut state in which fuel injection to the internal combustion engine 10 is stopped as the vehicle is decelerating, and the internal combustion engine 10 is stopped. For example, the vehicle is being driven by the driving motor.

  If it is determined to be in the permitted state, cleaning control is executed by the subroutine processing shown in FIG. 10 in the subsequent step S60, and the heater operation time is reset to zero in the next step S70. Next, a cleaning control processing procedure shown in FIG. 10 will be described.

  First, in step S61 of FIG. 10, the operation of the fuel injection valve 33 is stopped to stop fuel injection from the injection hole 33a. In subsequent step S62, the temperature of the air flowing into the vaporizing chamber 36a from the air inlet 36d is acquired. Specifically, the detection value of an intake air temperature sensor (not shown) arranged in the intake passage 10in is acquired as the temperature of the air flowing into the vaporizing chamber 36a.

  In subsequent step S63, a target heater temperature is set in accordance with the acquired air temperature. For example, the target heater temperature is set to a higher value as the air temperature is lower. The target heater temperature at the time of cleaning is set to a value higher than the target heater temperature at the time of reforming / reducing agent generation. Specifically, the lower limit value of the target heater temperature set in step S63 is higher than the upper limit value of the target heater temperature calculated in step S24 of FIG.

  In subsequent step S64, the heater actual temperature (heating degree) which is the actual temperature of the heating surface 34a is acquired. Specifically, the detection value of the temperature sensor 37 is acquired as the heater actual temperature. In subsequent step S65, a deviation between the target heater temperature set in step S63 and the actual heater temperature acquired in step S64 is calculated, and the heater heating duty ratio is set based on the deviation. In the subsequent step S66, the current supply to the electric heater 34 is duty-controlled according to the set heater heating duty ratio.

  For example, when the heater actual temperature is lower than the target heater temperature, the heater heating duty ratio is set to be larger as the deviation is larger, so that the heater actual temperature is quickly raised to the target heater temperature. Further, when the heater actual temperature is higher than the target heater temperature, the heater heating duty ratio is set to be small so that the heater actual temperature is lowered to the target heater temperature.

  In the subsequent step S67, it is determined whether or not a predetermined time (for example, 1 second) has elapsed after the heater actual temperature has risen to reach the target heater temperature. If it is determined that the predetermined time has not elapsed, the processes of steps S64, S65, and S66 are repeatedly executed. If it is determined that the predetermined time has elapsed, the cleaning control shown in FIG. 10 is terminated.

  As described above, since the highly active substance adding device according to the present embodiment includes the electric heater 34 that heats and vaporizes the liquid fuel, the reforming is performed while suppressing the problem that the liquid fuel adheres to the electrode 21. A reducing agent can be produced. Nevertheless, the component (deposit) deposited in the vaporization chamber without being vaporized in the liquid fuel can be burned and removed by the next cleaning control. In this cleaning control, the deposit can be burned and removed by operating the electric heater 34 while the fuel supply is stopped to make it empty, and allowing air to flow into the vaporizing chamber 36a.

  Therefore, it is possible to suppress the deterioration of the heat transfer from the heating surface 34a to the fuel due to the deposit adhering to the heating surface 34a of the electric heater 34, and it is possible to suppress the rapid vaporization of the fuel from being inhibited by the deposit. Moreover, it can suppress that supply of the gaseous fuel to the mixing chamber 31a is obstructed when the jet nozzle 36b is clogged with deposits.

  Furthermore, in this embodiment, the air inflow port 36d formed in the vaporizing case 36 is located below the jet port 36b. Therefore, convection described below occurs during cleaning control. That is, since the high-temperature gas in the vaporizing chamber 36a has a small specific gravity and is light, it is easy to be discharged from the jet port 36b positioned above, and is difficult to be discharged from the air inlet 36d positioned below. Therefore, the high temperature gas in the vaporization chamber 36a is discharged from the jet port 36b, and convection occurs such that air flows into the vaporization chamber 36a from the air inlet 36d by the amount of the discharge. Therefore, the inflow of air into the vaporizing chamber 36a can be promoted, and the possibility that the deposit cannot be sufficiently combusted due to insufficient oxygen can be suppressed.

  In particular, during the cleaning control, the internal combustion engine 10 may stop and the compressor 11c may stop. Even in this case, air can be caused to flow into the vaporization chamber 36a by the convection, and the effect of the convection can be achieved. Is remarkably exhibited. In addition, during reforming control, the vaporization chamber 36a has a high pressure due to the vaporization of fuel, so that the inflow of air from the air inlet 36d can be suppressed. Note that even when gaseous fuel flows out from the air inlet 36d during the reforming control, the gaseous fuel that has flowed out only flows into the mixing chamber 31a through the second air passage 30c, the internal space 30a, and the gap CL. do not become.

  Furthermore, in the present embodiment, a branch passage (first branch passage 35b) that guides air to the vaporization chamber 36a branches from an air passage (first air passage 35a) that guides air to the mixing chamber 31a. For this reason, the branch passage is located upstream of the mixing chamber 31a, so that the pressure in the branch passage is higher than that of the mixing chamber 31a. Therefore, it is possible to promote air inflow from the air inlet 36d to the vaporizing chamber 36a during cleaning control.

  Further, in the present embodiment, a throttle portion 30d for reducing the air flow rate is provided in a portion of the first air passage 35a on the downstream side of the first branch passage 35b. Therefore, the pressure difference between the mixing chamber 31a and the first branch passage 35b is increased. Therefore, it is possible to promote the air flow during the execution of the cleaning control means, that is, the discharge of the high temperature gas from the jet port 36b and the inflow of the low temperature air from the air inlet 36d.

  Furthermore, in this embodiment, the fuel supplied to the vaporization chamber 36a is injected in the atomized state from the fuel injection valve 33. And the air inflow port 36d is arrange | positioned outside the injection range. Therefore, the fuel injected from the injection hole 33a can be prevented from leaking from the air inlet 36d.

  Furthermore, in this embodiment, the temperature sensor 37 is provided in the vaporization chamber 36a, and the target heater temperature is set based on the detection value of the temperature sensor 37, whereby the heater temperature and the heater operation time are controlled according to the actual heater temperature. .

  Contrary to this embodiment, if the temperature sensor 37 is abolished and the electric heater 34 is operated at a predetermined temperature for a predetermined time at the time of cleaning control, the following problems are concerned. That is, for example, when the outside air temperature is low (for example, −35 ° C.), the temperature of the air flowing in from the air inlet 36d is also low. Therefore, if the electric heater 34 is operated at the above-mentioned predetermined temperature and predetermined time, there is a concern that the deposit cannot be heated sufficiently and the cleaning becomes insufficient. On the other hand, in this embodiment, since the electric heater 34 is operated based on the detection value of the temperature sensor 37 as described above, the above-mentioned concern can be reduced.

  Furthermore, in this embodiment, the heat exchanger 10a which heats the air which flows in from the air piping 32 is provided. Therefore, the oxygen gas supplied to the discharge reactor 20 is heated and the temperature rises. Therefore, it is possible to suppress the fuel injected from the fuel injection valve 33 and vaporized by the electric heater 34 from being cooled by the oxygen gas in the mixing chamber 31 a, condensed and attached to the electrode 21. Therefore, the problem that the reforming / reducing agent is added unintentionally at a low exhaust temperature or the addition of the reforming / reducing agent is delayed, that is, the timing of adding the reforming / reducing agent to the exhaust passage 10ex as intended. It is possible to suppress a problem that the control becomes impossible.

  Furthermore, in this embodiment, the heat exchanger 10a heats oxygen gas using the heat generated in the internal combustion engine 10. Therefore, since the waste heat of the internal combustion engine 10 is effectively used, energy consumption that occurs when oxygen gas is heated using, for example, an electric heater can be eliminated.

  Further, in the present embodiment, the heat exchanger 10a is attached to the reflux pipe 10egr, and heats the oxygen gas using the heat of the EGR gas. Here, the recirculation pipe 10egr is arranged so as to protrude outside the exhaust manifold 10m. Therefore, for example, compared with the case where the heat exchanger 10a is attached to the exhaust manifold 10m, according to this embodiment attached to the reflux pipe 10egr, the attachment workability can be improved and the mounting space for the heat exchanger 10a can be easily secured. . Further, since the EGR gas is exhaust immediately after being discharged from the combustion chamber, it is at a high temperature. Therefore, according to the present embodiment in which the high temperature EGR gas is used for heating the oxygen gas, the oxygen gas can be efficiently heated.

  Furthermore, in this embodiment, the discharge reactor 20 which ionizes supplied oxygen gas by discharge and makes it active oxygen, and the fuel injection valve 33 which supplies a fuel to the discharge reactor 20 are provided. And the ozone production | generation control means by FIG.8 S22 and the reforming control means by step S26 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.

  Here, when the liquid fuel adheres to the electrode 21, when switching from the generation of the reforming / reducing agent to the generation of ozone, the adhering fuel is vaporized and the electrode is vaporized even though the fuel supply is stopped. There will be fuel in the inter-passage 21a. Then, the active oxygen generated by the discharge oxidizes the fuel to generate a reforming and reducing agent, and the amount of ozone that is generated by oxidizing oxygen molecules is reduced. On the other hand, according to this embodiment, since the fuel adhesion to the electrode 21 can be suppressed as described above, it is possible to suppress the problem that the reforming / reducing agent is generated when the ozone generation flag is on.

  Further, in the present embodiment, the low-temperature intake pipe 10 c that supplies the low-temperature intake air after being cooled by the cooler 12 to the discharge reactor 20, and the high-temperature intake pipe that supplies the oxygen gas heated by the heat exchanger 10 a to the discharge reactor 20. 10h. Then, the operation of the switching valve 32a is performed by steps S15 and S16 of FIG. 7 so that the low temperature intake pipe 10c communicates with the discharge reactor 20 when ozone is generated, and the high temperature intake pipe 10h communicates with the discharge reactor 20 when reformed reducing agent is generated. Control. According to this, since the low temperature intake air is supplied at the time of ozone generation, it is possible to suppress the generated ozone from being destroyed by the heat of the intake air.

  Further, in the present embodiment, the high temperature intake pipe 10 h supplies the high temperature intake air before being cooled by the cooler 12 among the intake air supercharged by the supercharger 11 to the discharge reactor 20. For this reason, when the reforming / reducing agent is generated, the intake air whose temperature has increased due to the compression of the compressor 11c and which has not been cooled by the cooler 12 is supplied. Therefore, when the reforming / reducing agent is generated, the oxygen gas can be promoted to a high temperature, and the suppression of the gaseous fuel condensing and adhering to the electrode 21 can be promoted.

  Furthermore, in this embodiment, the fuel cracked by the electric heater 34 is supplied to the discharge reactor 20, so that the fuel is partially oxidized with the oxygen gas ionized by the discharge reactor 20 to generate a reforming reductant. To do. Therefore, since the boiling point of the fuel is lowered by being cracked, the fuel is suppressed from being liquefied again when the vaporized fuel is cooled by oxygen gas and the temperature is lowered. As a result, suppression of the gaseous fuel condensing and adhering to the electrode 21 can be promoted.

  Furthermore, in this embodiment, the fuel injection valve 33 which supplies the liquid fuel to the electric heater 34 in the state atomized is provided. Therefore, the time required to vaporize and crack the liquid fuel with the electric heater 34 is shortened. Therefore, the responsiveness of the addition of the modified reducing agent with respect to the necessary reducing agent amount can be accelerated.

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 a low temperature. 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.

(Second Embodiment)
In the first embodiment, part of the intake air compressed by the compressor 11 c is introduced into the air pipe 32. In contrast, in this embodiment, as shown in FIG. 11, the low temperature intake pipe 10c, the high temperature intake pipe 10h, and the switching valve 32a are eliminated, and an air pump 32p is provided. The air blown by the air pump 32p flows into the mixing chamber 31a through the air pipe 32. The air blown by the air pump 32p is a normal temperature and normal pressure atmosphere existing around the highly active substance adding device. Since air contains oxygen molecules, the air blown by the air pump 32p corresponds to the oxygen gas described above.

  The heat exchanger 10a described above is attached to the air pipe 32 in this embodiment. In addition, you may comprise the path | pass which bypasses the heat exchanger 10a, and can switch between the case where air is heated with the heat exchanger 10a, and the case where it bypasses the heat exchanger 10a and makes it non-heating.

  The air pump 32p is driven by an electric motor, and the electric motor is controlled by the microcomputer 81. The microcomputer 81 operates the air pump 32p during the reforming control in step S26 in FIG. 8 and the ozone generation control in step S22, and also in the cleaning control in step S60 in FIG.

  Also, as shown in FIG. 12, when it is determined in step S67 that the predetermined time has elapsed since the heater actual temperature rose and reached the target heater temperature, in step S68, the electric heater in step S66 is obtained. The duty control 34 is terminated. Further, the air pump 32p is operated for a certain time (for example, 3 seconds). During this operation, the air flow rate is increased as compared with the duty control in step S66.

  As described above, in the highly active substance addition device according to the present embodiment, the air pump 32p is used to blow air to the mixing chamber 31a used to generate the reforming and reducing agent, and the air pump 32p is also used during cleaning control. Operate. Therefore, since the air pump 32p used for reforming control is also used for cleaning control, a dedicated air pump for blowing air to the vaporizing chamber 36a can be eliminated.

  Further, in the present embodiment, after the completion of the cleaning control in step S66, the air pump 32p is operated with a larger air flow rate than when the cleaning control is performed. Therefore, it is possible to suppress the ash generated by the combustion by the cleaning control from being discharged from the ejection port 36b and the ash being deposited in the vaporizing chamber 36a. Further, the ash remaining on the heating surface 34a can be blown off by the air blow by the air pump 32p. Therefore, it can suppress that vaporization of the liquid fuel adhering to the heating surface 34a is prevented by ash.

  Furthermore, in this embodiment, the low temperature intake pipe 10c and the high temperature intake pipe 10h shown in FIG. 1 can be eliminated. Therefore, when adjusting the intake air amount by the throttle valve 13, it is not necessary to correct the intake air amount branched to the air pipe 32, so that the intake air amount taken into the combustion chamber can be accurately adjusted.

(Third embodiment)
In the second embodiment, the discharge reactor 20 is installed downstream of the electric heater 34 in the air flow. On the other hand, in this embodiment, as shown in FIG. 13, the discharge reactor that functions as the ozone generator 20 </ b> A is installed upstream of the electric heater 34 in the air flow. The air blown by the air pump 32p flows into the ozone generator 20A. The ozone generator 20A has the same structure as that of the discharge reactor 20 shown in FIGS. 1 and 2, and when discharged between the electrodes 21, ozone is generated from oxygen in the air. The ozone thus generated is supplied together with air to the vaporizing chamber 36a through the air pipe 32b.

  In the second embodiment, the fuel is partially oxidized inside the discharge reactor 20 to be reformed. On the other hand, in this embodiment, the fuel injected from the fuel injection valve 33 is partially oxidized with oxygen contained in the air by heating in the vaporizing chamber 36a. And the reaction of the said partial oxidation can be promoted by producing | generating ozone and making it flow into the vaporization chamber 36a. The fuel (reducing agent) thus reformed is added to the exhaust passage 10ex through the supply pipe 24.

When the temperature of the reduction catalyst is low and the NOx reduction rate is low even when a reducing agent is added, ozone supply control described below is performed. That is, in the ozone supply control, the ozone generator 20A is discharged while operating the air pump 32p to generate ozone, and the fuel injection by the fuel injection valve 33 and the heating by the electric heater 34 are stopped. As a result, the generated ozone is added to the exhaust passage 10ex through the supply pipe 24. As a result, NO in the exhaust is oxidized to NO ₂ by ozone. Since the NOx adsorption amount can be improved by oxidizing NO in this way, the amount of NOx released to the atmosphere without being purified by the NOx purification device 15 can be reduced.

  The air pump 32p is driven by an electric motor, and the electric motor is controlled by the microcomputer 81. The microcomputer 81 operates the air pump 32p during the reforming control in step S26 in FIG. 8 and the ozone generation control in step S22, and also in the cleaning control in step S60 in FIG.

  Also, as shown in FIG. 12, when it is determined in step S67 that the predetermined time has elapsed since the heater actual temperature rose and reached the target heater temperature, in step S68, the electric heater in step S66 is obtained. The duty control 34 is terminated. Further, the air pump 32p is operated for a certain time (for example, 3 seconds). During this operation, the air flow rate is increased as compared with the duty control in step S66. In short, also in the present embodiment, as in FIG. 12, the air pump 32p is operated not only when the reforming control means is executed but also when the cleaning control means is executed. In addition, after the execution of the cleaning control means is completed, the air pump 32p is operated with a larger air flow than when the cleaning control means is executed.

  As described above, in the highly active substance addition device according to the present embodiment, deposits generated without being vaporized out of the liquid fuel are less likely to adhere to the discharge reactor 20, and the cleaning control is the same as in the second embodiment. It can be operated similarly.

  Further, in the present embodiment, an ozone generator 20A that generates ozone from oxygen in the air is provided, and the ozone generated by the ozone generator 20A is supplied to the vaporization chamber 36a. Thus, even if it is the structure which supplies ozone to the vaporization chamber 36a, a reforming reducing agent can be produced | generated and added.

Contrary to this embodiment, when the electric heater 34 and the cleaning control means are not provided, the fuel is unlikely to adhere to the inside of the ozone generator 20A, but adheres to various passages such as the vaporization chamber 36a and the supply pipe 24. There is concern. In response to this concern, in the present embodiment, the electric heater 34 is provided to vaporize the fuel, so that the problem of liquid fuel adhering to the vaporization chamber 36a, the supply pipe 24, etc. is suppressed and the reforming control means controls the modification. A quality reducing agent can be produced. Nevertheless, deposits deposited in the vaporization chamber 36a without being vaporized in the liquid fuel can be burned and removed under the control of the cleaning control means. That is, new problems such as deposit accumulation caused by providing the electric heater 34 can be suppressed. (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 embodiment shown in FIG. 1, a heat exchanger 10a is attached to the reflux pipe 10egr. On the other hand, you may attach the heat exchanger 10a to the downstream exhaust pipe demonstrated below. The downstream exhaust pipe forms an exhaust passage 10ex on the downstream side of the exhaust manifold 10m, and more specifically, forms an exhaust passage 10ex located on the downstream side of the DPF 14 and the upstream side of the NOx purification device 15.

  Here, the downstream exhaust pipe is disposed so as to project outside the exhaust manifold 10m. Therefore, for example, compared with the case where the heat exchanger 10a is attached to the exhaust manifold 10m, according to this embodiment attached to the downstream exhaust pipe, the attachment workability can be improved. Further, it is possible to easily secure the mounting space for the heat exchanger 10a.

  In addition, it is desirable that the discharge reactor 20 and the mixing vessel 31 be arranged in the vicinity of the NOx purification device 15. With such arrangement, there is a high probability that the downstream exhaust pipe is located in the vicinity of the mixing vessel 31. Therefore, when the heat exchanger 10a is attached to the downstream exhaust pipe as described above, it is possible to easily arrange the heat exchanger 10a in the vicinity of the mixing container 31, and thus the pipe length of the high-temperature intake pipe 10h can be shortened.

  Alternatively, the heat exchanger 10a may be attached to the exhaust manifold 10m. Since the exhaust manifold 10m is at a high temperature because the exhaust gas immediately after being discharged from the combustion chamber flows, it can efficiently heat the oxygen gas.

  In the embodiment shown in FIG. 1, the oxygen gas is heated using the heat generated in the internal combustion engine 10. On the other hand, the oxygen gas may be heated using cooling water for cooling the inverter or the internal combustion engine 10 as a heat source, or the oxygen gas may be heated using an electric heater.

  In the embodiment shown in FIG. 1, liquid fuel is injected and atomized from the injection hole 33 a of the fuel injection valve 33. On the other hand, the fuel injection valve 33 may be replaced with an electromagnetic valve so that the fuel supplied from the pump 33p flows out to the vaporizing case 36 without being atomized and is temporarily stored in the vaporizing case 36.

  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. In the embodiment shown in FIG. 1, the liquid fuel is supplied from the fuel injection valve 33 to the mixing chamber 31a. However, the liquid fuel is heated and vaporized outside the mixing chamber 31a, and the gaseous fuel is mixed into the mixing chamber 31a. You may make it supply to 31a.

  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 case of a complete stop in which both the generation of ozone and the generation of the reforming reducing agent are stopped, the discharge by the discharge reactor 20 may be stopped to suppress wasteful power consumption. 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 case of the complete stop, power consumption may be reduced by stopping the operation of the air pump 32p and stopping the supply of oxygen gas.

  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 first embodiment, the NOx catalyst temperature used in step S <b> 12 of FIG. 7 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, 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, 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, 21 ... Electrode, 33 ... Fuel injection valve (hydrocarbon supply means), 34 ... Electric heater (heating means), 36a ... Vaporization chamber , S25, S26 ... reforming control means, S60 ... cleaning control means.

Claims (10)

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,
Hydrocarbon supply means (33) for supplying liquid hydrocarbons to the vaporization chamber (36a);
Heating means (34) for heating and vaporizing the liquid hydrocarbons supplied to the vaporization chamber;
Reforming control means (S25, S26) for generating a reforming and reducing agent as the highly active substance by operating the hydrocarbon supply means and the heating means;
By operating the heating means while stopping the operation of the hydrocarbon supply means, and allowing air to flow into the vaporization chamber, the components deposited in the vaporization chamber without being vaporized out of the liquid hydrocarbons. Cleaning control means (S60) for removing by burning;
A highly active substance adding device comprising: It has an electrode (21) for ionizing oxygen gas containing at least oxygen by discharge, and gas hydrocarbons vaporized by the heating means are oxidized by the ionized oxygen gas to be reformed as the highly active substance A discharge reactor (20) for generating a reducing agent;
The high-activity substance addition device according to claim 1, wherein the discharge reactor is arranged so that the gaseous hydrocarbon is supplied from the vaporization chamber to the discharge reactor. A vaporizing case (36) for forming the vaporizing chamber therein;
The vaporization case is
A hydrocarbon outlet (36b) for causing the vaporized hydrocarbon to flow out of the vaporization chamber to the discharge reactor during the execution of the reforming control means;
An air inlet (36d) for allowing air to flow into the vaporizing chamber during execution of the cleaning control means;
Have
The highly active substance adding device according to claim 2, wherein the air inlet is located below the hydrocarbon outlet. A mixing chamber (31a) for mixing the gaseous hydrocarbon and oxygen gas supplied to the discharge reactor, and a mixing vessel (31) for supplying the mixed gas to the discharge reactor;
A branch passage (35b, 35c, 35d) for guiding air to the vaporization chamber is branched from an air passage (35a, 30c, 30a) for guiding air used as the oxygen gas to the mixing chamber. The highly active substance addition apparatus according to claim 2 or 3,   The highly active substance addition device according to claim 1, further comprising an ozone generator (20A) for generating ozone from oxygen in the air, wherein the ozone generated by the ozone generator is supplied to the vaporizing chamber. . An air pump (32p) for blowing air to the vaporizing chamber;
6. The highly active substance addition device according to claim 4, wherein the air pump is operated not only when the reforming control means is executed but also when the cleaning control means is executed.   7. The highly active substance addition device according to claim 6, wherein after the execution of the cleaning control means is completed, the air pump is operated with a larger air flow rate than when the cleaning control means is executed.   The highly active substance addition device according to claim 4, wherein a throttle portion (30d) for reducing the flow rate of air is provided in a portion of the air passage downstream of the branch passage. The hydrocarbon supply means atomizes liquid hydrocarbons and injects them into the vaporization chamber,
The air inflow port (36d) for allowing air to flow into the vaporizing chamber is disposed outside the injection range of hydrocarbons by the hydrocarbon supply means. The highly active substance addition apparatus as described. A temperature sensor (37) for detecting the actual degree of heating by the heating means;
The highly active substance addition apparatus according to claim 1, wherein the degree of heating by the heating unit is controlled based on a detection value of the temperature sensor.

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