JP2004353596A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of suitably burning and removing soot or SOF adhering and accumulating on an electrode of a plasma generating device. <P>SOLUTION: The exhaust emission control device equipped with an after-treatment device (catalyst regeneration type particulate filter 10) making exhaust gas 8 passing therethrough and purifying the same in a middle of an exhaust pipe 9 of an internal combustion engine (diesel engine 1) is provided with the plasma generating device 11 generating plasma by carrying out electrical discharge in the exhaust gas 8 in an upstream side of the after-treatment device, a flow through type oxidation catalyst 12 installed in a preceding stage of the plasma generating device 11, a fuel adding means (control device 17) adding fuel in the exhaust gas 8 in an upstream side of the oxidation catalyst 12, and a temperature raising means (intake air throttle valve 22 or control device 17) raising exhaust gas temperature to temperature enabling oxidation reaction of the fuel added by the fuel adding means in the oxidation catalyst 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas purification device.
[0002]
[Prior art]
Particulate matter (particulate matter) discharged from the diesel engine is mainly composed of soot composed of carbonaceous material and SOF component (Soluble Organic Fraction: soluble organic component) composed of a high-boiling hydrocarbon component. Although it has a composition containing a small amount of sulfate (mist-like sulfuric acid component), as a measure to reduce this kind of particulates, it is necessary to equip a particulate filter in the middle of the exhaust pipe through which exhaust gas flows. This has been done conventionally.
[0003]
This kind of particulate filter has a porous honeycomb structure made of ceramic such as cordierite, and the inlets of the respective flow paths partitioned in a lattice are alternately plugged, and the inlets are not plugged. The outlets of the flow passages are sealed so that only the exhaust gas that has passed through the thin porous wall that defines each flow passage is discharged to the downstream side.
[0004]
Since the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging, and the particulate filter is removed. It is necessary to regenerate, but under normal operating conditions of the diesel engine, there is little opportunity to obtain a high exhaust temperature enough for the particulates to self-combust, so for example, an oxidation catalyst made of alumina loaded with platinum It has been studied to employ a catalyst regeneration type particulate filter in which the catalyst is integrally supported on the particulate filter, or an oxidation catalyst is separately provided in front of the particulate filter.
[0005]
That is, if such a catalyst regeneration type particulate filter is employed, the oxidation reaction of the collected particulates is promoted, the ignition temperature is lowered, and the particulates can be burned and removed even at a lower exhaust temperature than before. It is possible.
[0006]
In addition to the particulate filter described above, it has also been proposed to equip a middle part of an exhaust pipe as a post-treatment device with a selective reduction catalyst or a NOx storage reduction catalyst for removing NOx in exhaust gas, In particular, in recent years, post-processing devices that combine a particulate filter with a NOx storage reduction catalyst have also been developed.
[0007]
However, even when any of these post-treatment devices is employed, the exhaust gas temperature must be higher than a predetermined temperature in order to surely remove and remove the particulates and to obtain sufficient catalytic activity. If the operation state (in general, the low-temperature operation region is widened in the light-load operation region) continues, there is a problem that the after-treatment device cannot be functioned sufficiently. As described above, in a vehicle that travels only on a congested road, since the operation at a required predetermined temperature or higher does not continue for a long time, there is a possibility that the exhaust purification effect provided by the aftertreatment device may not be sufficiently obtained. .
[0008]
For this reason, it has been studied to arrange a plasma generator in front of the post-processing device so that the exhaust gas can be sufficiently purified by the post-processing device even in an operation region where the exhaust gas temperature is low. If plasma is generated by discharging into the exhaust gas on the upstream side of the device, the exhaust gas is excited, radically activated unburned hydrocarbons, oxygen becomes ozone, NO becomes NO ₂ , Since these exhaust gas excited components are in the activated state, the effect of purifying the exhaust gas by the post-processing device can be obtained from the exhaust temperature range lower than before.
[0009]
Regarding an exhaust gas purifying apparatus in which a plasma generator is arranged in front of a particulate filter, for example, the following Patent Document 1 and the like already exist as prior art documents.
[0010]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2002-276333
[Problems to be solved by the invention]
However, since the electrodes of such a plasma generator are exposed to the flow of the exhaust gas containing the particulates, carbonaceous soot and SOF deposit and accumulate, causing a current leak, thereby causing a current between the electrodes. There is a fear that it becomes difficult to apply a voltage, which may hinder the generation of plasma.
[0012]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide an exhaust gas purification apparatus capable of appropriately burning and removing soot and SOF from the electrodes of a plasma generator.
[0013]
[Means for Solving the Problems]
The present invention is an exhaust gas purification apparatus equipped with a post-processing device for purifying exhaust gas by passing it through the exhaust pipe of an internal combustion engine, and discharges the exhaust gas upstream of the post-processing device to generate plasma. A plasma generator to be produced, a flow-through type oxidation catalyst provided upstream of the plasma generator, fuel addition means for adding fuel to exhaust gas on the upstream side of the oxidation catalyst, and addition by the fuel addition means. A temperature raising means for raising the exhaust gas temperature to a temperature at which the oxidation reaction of the selected fuel on the oxidation catalyst is enabled.
[0014]
In this way, by discharging the exhaust gas into the exhaust gas by the plasma generator to excite the exhaust gas, oxygen becomes ozone and NO becomes NO ₂ in a radically activated unburned hydrocarbon. Since the exhaust gas excited component is in the activated state, the effect of purifying the exhaust gas by the post-processing device can be obtained from the exhaust temperature range lower than before.
[0015]
Then, when soot and SOF in the exhaust gas adhere to and accumulate on the electrode of the plasma generator, and when it becomes necessary to remove the soot and SOF, the fuel is added by the fuel addition means on the upstream side of the oxidation catalyst. If added, the added fuel undergoes an oxidation reaction with the oxidation catalyst to generate heat of reaction, and the heat of reaction causes the exhaust gas passing through the oxidation catalyst to be heated significantly. As a result, the exhaust gas heated through the oxidation catalyst is heated. The soot and SOF that have been introduced into the plasma generator and deposited on the electrode are burnt and removed.
[0016]
In addition, even if the operation is performed in an operation region in which the exhaust gas temperature is extremely low so that the added fuel cannot be oxidized on the oxidation catalyst, the fuel temperature is increased by the temperature increasing means and then the fuel is added by the fuel adding means. What is necessary is just to add.
[0017]
Further, when the exhaust gas purifying apparatus of the present invention is more specifically implemented, a temperature sensor for detecting the exhaust gas temperature is arranged between the oxidation catalyst and the plasma generator, and the detected value of the temperature sensor is equal to a predetermined threshold. The fuel addition by the fuel addition means is appropriately performed only under the condition of exceeding, and when the detection value of the temperature sensor is equal to or less than the predetermined threshold value, the fuel by the fuel addition means is sandwiched by the temperature rise of the exhaust gas by the temperature rise means. It is preferable that the addition is appropriately performed.
[0018]
Further, in the present invention, it is preferable that the fuel addition means is a fuel injection control means for performing post injection at a non-ignition timing later than the compression top dead center for the fuel injection device following the main injection.
[0019]
Further, the temperature raising means for raising the exhaust gas temperature may be an intake throttle means for appropriately reducing the intake air flow rate, or may perform the main injection with a delay from the normal injection timing to the fuel injection device within a combustible range. The fuel injection control means may be a fuel injection control means or a fuel injection control means for performing an after-injection at a combustible timing immediately after the main injection to the fuel injection device.
[0020]
That is, when the temperature raising means for raising the exhaust gas temperature is an intake throttle means for appropriately narrowing the intake air flow rate, when the intake air flow rate is reduced by the intake throttle means in an operating state where the exhaust temperature is low, the working air of the internal combustion engine is reduced. As the amount decreases, the pumping loss increases, thereby increasing the fuel injection amount to generate the required output and raising the exhaust gas temperature, while reducing the amount of exhaust gas generated by combustion in the internal combustion engine. The exhaust temperature can be further increased by lowering the heat capacity.
[0021]
Further, when the temperature raising means for raising the exhaust gas temperature is the fuel injection control means for performing the main injection by delaying the fuel injection device from the normal injection timing within a combustible range, the fuel of the delayed injection is output. By burning the fuel at a timing that is difficult to convert to fuel, the thermal efficiency of the internal combustion engine decreases, the amount of heat generated by the fuel that is not used for power increases, and the exhaust gas temperature increases.
[0022]
Further, when the temperature raising means for raising the exhaust gas temperature is the fuel injection control means for performing the after-injection at a combustible timing immediately after the main injection to the fuel injection device, it is difficult to convert the fuel of the after-injection into the output. Combustion at the timing lowers the thermal efficiency of the internal combustion engine, increases the amount of heat generated by the fuel that is not used for power, and increases the exhaust gas temperature.
[0023]
In the present invention, at least one of the current and the voltage when plasma is generated by the plasma generator is monitored to determine the occurrence of a leak to determine whether or not the fuel addition is required. Is preferably provided, and in this case, unnecessary fuel addition can be avoided as much as possible.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0025]
FIGS. 1 to 3 show an example of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a diesel engine (internal combustion engine) equipped with a turbocharger 2, and intake air guided from an air cleaner 3. The intake air 4 is guided to the compressor 2 a of the turbocharger 2 through the intake pipe 5 and pressurized, and the pressurized intake air 4 is distributed to and introduced into each cylinder of the diesel engine 1 via the intercooler 6.
[0026]
Further, the exhaust gas 8 discharged from each cylinder of the diesel engine 1 through the exhaust manifold 7 is sent to the turbine 2b of the turbocharger 2, and the exhaust gas 8 that drives the turbine 2b is converted into a particulate filter 10 of a catalyst regeneration type. The particulates are collected through a (post-processing device) and then discharged.
[0027]
As shown in FIG. 2 in an enlarged manner, the particulate filter 10 has a porous honeycomb structure made of ceramic, and the inlets of the channels 10a partitioned in a lattice are alternately plugged, and the inlets are closed. The outlet of the unsealed flow path 10a is plugged, and only the exhaust gas 8 that has passed through the porous thin wall 10b that defines each flow path 10a is discharged to the downstream side. It is like that.
[0028]
Further, in front of the particulate filter 10, a plasma generator 11 for generating plasma by discharging into the exhaust gas 8 is provided, and in front of the plasma generator 11, as shown in FIG. A flow-through type oxidation catalyst 12 having a honeycomb structure is accommodated therein.
[0029]
In the plasma generator 11, the electrodes 13 and 14 are arranged so as to be opposed to each other so that a discharge can be caused between them. However, the distance between the electrodes 13 and 14 can be set substantially uniformly. For example, various shapes such as a plate type, a rod type, and a cylindrical type can be appropriately combined and adopted.
[0030]
In addition, a power supply 16 is connected to each of the electrodes 13 and 14 via a discharge control unit 15. In this embodiment, a battery mounted on a vehicle is assumed as the power supply 16. The control unit 15 raises the voltage of the power supply 16 to an appropriate dischargeable voltage and supplies power to each of the electrodes 13 and 14. The discharge control unit 15 forms an engine control computer (ECU: Electronic Control Unit). It is controlled in response to a command signal 15a from the control device 17.
[0031]
A temperature sensor 18 for detecting an exhaust gas temperature is provided between the oxidation catalyst 12 and the plasma generator 11, and a temperature signal 18a of the temperature sensor 18 is input to the controller 17. ing.
[0032]
Since the control device 17 also serves as an engine control computer, the control device 17 also controls fuel injection, and more specifically, an accelerator sensor 19 (which detects an accelerator opening as a load on the diesel engine 1). A fuel injection device 21 that injects fuel into each cylinder of the diesel engine 1 based on an accelerator opening signal 19a from the load sensor) and a rotation speed signal 20a from a rotation sensor 20 that detects the engine rotation speed of the diesel engine 1. , A fuel injection signal 21a is output.
[0033]
Here, the fuel injection device 21 is constituted by a plurality of injectors provided for each cylinder, and the solenoid valves of these injectors are appropriately opened by the fuel injection signal 21a to control the fuel injection timing. (Valve opening timing) and the injection amount (valve opening time) are appropriately controlled.
[0034]
On the other hand, in the control device 17, while the fuel injection signal 21a in the normal mode is determined based on the accelerator opening signal 19a and the rotation speed signal 20a, when it becomes necessary to perform the fuel addition by the post injection. The fuel is switched from the normal mode to the electrode regeneration mode, and the fuel is injected in the vicinity of the compression top dead center (crank angle 0 °), followed by the post injection at the non-ignition timing later than the compression top dead center. The injection signal 21a is determined.
[0035]
That is, if the post injection is performed at the non-ignition timing later than the compression top dead center following the main injection, unburned fuel (mainly hydrocarbons) is added to the exhaust gas 8 by the post injection. That is, the unburned fuel is oxidized by the oxidation catalyst 12 to generate reaction heat, and the reaction heat causes the exhaust gas 8 passing through the oxidation catalyst 12 to be heated significantly.
[0036]
However, in the control device 17, based on the temperature signal 18 a from the temperature sensor 18, the temperature exceeds a temperature (predetermined threshold value) at which the oxidation reaction of the fuel added by the post-injection in the oxidation catalyst 12 becomes possible. The fuel addition by post-injection is performed only under certain conditions, and when the temperature is lower than the temperature, the fuel addition by post-injection is performed with the exhaust gas temperature rising by a temperature-raising means described later.
[0037]
In other words, in the example shown here, the intake throttle valve 22 (intake throttle means) provided in the middle of the intake pipe 5 is supplied with an opening degree command signal 22a from the control device 17 to be independent of the original operation. , The intake throttle valve 22 is used as a temperature raising means for raising the exhaust gas temperature. In the operation state where the exhaust gas temperature is low, the intake throttle valve 22 reduces the intake flow rate. When executed, the pumping loss increases due to a decrease in the working air amount of the diesel engine 1, whereby the fuel injection amount is increased to generate a required output and the exhaust temperature is raised, while the combustion in the diesel engine 1 is performed. As a result, the amount of exhaust gas 8 generated decreases and the heat capacity decreases, thereby further increasing the exhaust temperature.
[0038]
It is also possible to utilize the control device 17 which also serves as a fuel injection control device as a temperature raising device for raising the exhaust gas temperature. The main injection may be performed with a delay within the combustible range from the timing, or the after-injection may be performed on the fuel injection device 21 at a combustible timing immediately after the main injection.
[0039]
In other words, if the main injection is performed with a delay within a combustible range from the normal injection timing, the fuel of the delayed injection is burned at a timing that is difficult to be converted into an output, thereby lowering the thermal efficiency of the diesel engine 1 and the heat generation amount of the fuel. Of these, the amount of heat not used for power increases, and the exhaust gas temperature rises.
[0040]
Further, if the after-injection is performed at a combustible timing immediately after the main injection, the fuel of the after-injection is burned at a timing that is difficult to be converted into an output, so that the thermal efficiency of the diesel engine 1 is reduced. The amount of heat not used for power increases, and the exhaust gas temperature rises.
[0041]
Then, the temperature raising means as described above sets the threshold temperature at which the added fuel cannot oxidize on the oxidation catalyst 12 based on the temperature signal 18a from the temperature sensor 18 as a threshold, and becomes lower than this threshold. When the temperature recovery mode is set, the temperature raising mode is operated with the temperature raising mode interposed therebetween as a pre-process for shifting to the electrode regeneration mode for executing post injection. The post-injection is performed under the condition that the value exceeds a predetermined threshold value.
[0042]
Thus, by configuring the exhaust gas purifying apparatus in this way, the plasma generator 11 discharges the exhaust gas 8 to excite the exhaust gas 8, so that the unburned hydrocarbons are radically oxygenated. Becomes ozone and NO becomes NO ₂ , and these exhaust gas excited components are in an activated state. Therefore, the oxidation reaction of the particulates collected by the particulate filter 10 is promoted by the exhaust gas excited components. Therefore, the particulates are ignited and burned and removed even at an exhaust temperature lower than in the past.
[0043]
When soot and SOF in the exhaust gas 8 adhere to and accumulate on the electrodes 13 and 14 of the plasma generator 11, and when it is necessary to remove the soot and SOF, the detection value of the temperature sensor 18 is used. The electrode regeneration mode is selected under the condition that exceeds the predetermined threshold, the fuel injection pattern is switched from the normal mode to the electrode regeneration mode by the control device 17, and after the main injection, the non-ignition after the compression top dead center is performed. As a result of adopting the injection pattern of performing post-injection at the timing, the post-injection causes the fuel added unburned in the exhaust gas 8 to undergo an oxidation reaction by the oxidation catalyst 12, thereby generating reaction heat. The temperature of the exhaust gas 8 passing through the oxidation catalyst 12 is significantly increased, and the exhaust gas 8 heated through the oxidation catalyst 12 is introduced into the plasma generator 11 and Adhering deposit on the electrode 13, 14 of the 11 are soot and SOF component is to be burned and removed.
[0044]
Further, even if the operation is performed in an operation region in which the exhaust gas temperature is extremely low so that the added fuel cannot be oxidized on the oxidation catalyst 12, the control device 17 which has received the temperature signal 18a from the temperature sensor 18 performs the electrode operation. As a pre-process for shifting to the regeneration mode, a temperature increase mode is interposed, and the intake throttle valve 22 is throttled to increase the temperature of the exhaust gas 8 reaching the oxidation catalyst 12 (combustible from normal injection timing). The main injection may be executed with a delay within the range, or the after injection may be executed at a combustible timing immediately after the main injection of fuel).
[0045]
Then, at the stage where the detection value of the temperature sensor 18 exceeds the predetermined threshold and the mode shifts to the electrode regeneration mode, the added fuel is oxidized by the oxidation catalyst 12 without fail. The heated exhaust gas 8 burns and removes soot and SOF deposited and deposited on the electrodes 13 and 14 of the plasma generator 11.
[0046]
It should be noted that whether or not soot and SOF attached to the electrodes 13 and 14 of the plasma generator 11 need to be removed is determined, for example, by controlling the voltage and current when the plasma is generated by the plasma generator 11 by controlling the controller 17. The determination means may be constantly monitored to determine the occurrence of a leak, but the post-injection may be performed periodically based on the operation time or the like.
[0047]
Therefore, according to the above-mentioned embodiment, after raising the exhaust temperature by the temperature raising means such as the intake throttle valve 22 if necessary, the fuel is added to the exhaust gas 8 by post-injection, and the added fuel is added to the oxidation catalyst 12. The temperature of the exhaust gas 8 passing through the oxidation catalyst 12 is significantly increased by the reaction heat generated by the oxidation reaction, and the exhaust gas 8 is introduced into the plasma generator 11 to deposit soot and SOF deposited on the electrodes 13 and 14. Since it is possible to burn and remove the components, it is possible to prevent current leakage due to the adhesion and deposition of soot and SOF beforehand, so that an appropriate voltage can be applied between the electrodes 13 and 14 without any trouble. Good plasma generation can be maintained.
[0048]
It should be noted that the exhaust gas purifying apparatus of the present invention is not limited to the above-described embodiment, and the post-processing apparatus is intended to remove NOx in exhaust gas in addition to the catalyst regeneration type particulate filter. A selective reduction catalyst, a NOx storage reduction catalyst, or the like may be employed. In addition, an injector is inserted through an appropriate position of an exhaust pipe (an exhaust manifold is also possible) for the fuel addition means, and the exhaust gas is exhausted by the injector. The fuel may be added by direct injection, and the three temperature raising means exemplified in the above-described embodiment may be used alone or in combination. Of course, various changes can be made without departing from the scope of the present invention.
[0049]
【The invention's effect】
According to the exhaust gas purification apparatus of the present invention described above, various excellent effects as described below can be obtained.
[0050]
(I) According to the invention as set forth in claim 1 of the present invention, if necessary, the temperature of the exhaust gas is raised by the temperature raising means, then the fuel is added to the exhaust gas by the fuel adding means, and the added fuel is converted to the oxidation catalyst. The temperature of the exhaust gas passing through the oxidation catalyst is significantly increased by the reaction heat generated by the oxidation reaction in step 1, and the exhaust gas is introduced into a plasma generator to burn off soot and SOF deposited on the electrodes. Therefore, it is possible to prevent a current leak due to soot and SOF adhesion and deposition, thereby maintaining a good plasma generation by applying an appropriate voltage between the electrodes without any trouble. Can be.
[0051]
(II) According to the invention described in claim 2 of the present invention, the amount of soot and SOF adhered to the electrode of the plasma generator is controlled by appropriately operating the fuel addition means and the temperature raising means based on the detection value of the temperature sensor. Can be efficiently removed by combustion.
[0052]
(III) According to the invention described in claim 3 of the present invention, a new control is only performed by performing post-injection control on the fuel injection device at a non-ignition timing later than the compression top dead center following the main injection. Unburned fuel can be added to the exhaust gas without requiring any additional equipment, and a rise in the cost of the fuel adding means can be suppressed.
[0053]
(IV) According to the invention of claim 4 of the present invention, the pumping loss is increased by reducing the amount of working air of the internal combustion engine, and the heat capacity is reduced by reducing the amount of exhaust gas generated by combustion in the internal combustion engine. Thus, the temperature of the exhaust gas reaching the oxidation catalyst can be reliably increased.
[0054]
(V) According to the invention of claim 5 of the present invention, the fuel of the delayed injection is burned at a timing at which it is difficult to convert the fuel into output, so that the thermal efficiency of the internal combustion engine is reduced and the power of the calorific value of the fuel is reduced. The amount of heat not used is increased, so that the temperature of the exhaust gas reaching the oxidation catalyst can be reliably increased.
[0055]
(VI) According to the invention described in claim 6 of the present invention, the fuel of the after-injection is burned at a timing that is difficult to be converted into an output, so that the thermal efficiency of the internal combustion engine is reduced and the power of the calorific value of the fuel is reduced. The amount of heat not used is increased, so that the temperature of the exhaust gas reaching the oxidation catalyst can be reliably increased.
[0056]
(VII) According to the invention of claim 7 of the present invention, unnecessary fuel addition can be avoided as much as possible, and the fuel addition cost can be suppressed to a necessary minimum.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of an embodiment for carrying out the present invention.
FIG. 2 is a sectional view showing details of the particulate filter of FIG. 1;
FIG. 3 is a partially cutaway perspective view showing details of the oxidation catalyst of FIG. 1;
[Explanation of symbols]
1 diesel engine (internal combustion engine)
8 Exhaust gas 9 Exhaust pipe 10 Particulate filter (post-processing device)
DESCRIPTION OF SYMBOLS 11 Plasma generator 12 Oxidation catalyst 13 Electrode 14 Electrode 17 Control device (fuel addition means: heating means; fuel injection control means: determination means)
18 Temperature sensor 21 Fuel injection device 22 Intake throttle valve (heating means)

Claims (7)

An exhaust purification device equipped with a post-processing device for purifying exhaust gas by passing it through the exhaust pipe of an internal combustion engine, wherein the plasma generating device discharges into the exhaust gas upstream of the post-processing device to generate plasma. And a flow-through type oxidation catalyst provided upstream of the plasma generator, fuel addition means for adding fuel to the exhaust gas on the upstream side of the oxidation catalyst, and fuel addition means for adding the fuel added by the fuel addition means. An exhaust gas purifying apparatus comprising: a temperature raising means for raising an exhaust gas temperature to a temperature at which an oxidation reaction on the oxidation catalyst is enabled. A temperature sensor for detecting the exhaust gas temperature is disposed between the oxidation catalyst and the plasma generator, and the fuel addition by the fuel addition means is appropriately performed only under the condition that the detected value of the temperature sensor exceeds a predetermined threshold. 2. The fuel supply system according to claim 1, wherein when the detected value of the temperature sensor is equal to or less than a predetermined threshold value, the fuel addition by the fuel addition unit is appropriately performed with the exhaust gas temperature increased by the temperature increase unit. An exhaust gas purification apparatus according to claim 1. 3. The fuel injection control device according to claim 1, wherein the fuel addition device is a fuel injection control device that performs post-injection at a non-ignition timing later than the compression top dead center to the fuel injection device following the main injection. Exhaust gas purification device. 4. The exhaust gas purifying apparatus according to claim 1, wherein the temperature increasing means for increasing the exhaust gas temperature is an intake throttle means for appropriately reducing an intake air flow rate. 4. A fuel injection control means for performing a main injection with a delay within a combustible range from a normal injection timing for a fuel injection device, wherein the temperature raising means for raising the exhaust gas temperature is a fuel injection control means. An exhaust gas purification apparatus according to claim 1. 4. The exhaust gas according to claim 1, wherein the temperature raising means for raising the exhaust gas temperature is a fuel injection control means for performing an after-injection at a combustible timing immediately after the main injection to the fuel injection device. Purification device. The apparatus further comprises a determination means for determining whether or not to perform fuel addition by monitoring at least one of a current and a voltage when plasma is generated by the plasma generator and determining whether or not to perform fuel addition. The exhaust gas purification apparatus according to claim 1.

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