JP2009041422A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device supplying active oxygen upstream a catalyst when exhaust gas temperature is not higher than catalyst activating temperature after engine start and inhibiting a problem that the active oxygen is decomposed before reaching the catalyst when flow speed of exhaust gas flowing in an exhaust passage upstream the catalyst is low. <P>SOLUTION: A control unit 20 operates an air supply pump 13 and an ozone generating device 14 and supplies ozone to the exhaust passage 3 upstream the catalyst 11 when the exhaust gas temperature detected by an exhaust gas temperature sensor 15 after start of an engine 1 is not higher than the activating temperature of the exhaust emission control catalyst 11. In this case, when the flow speed of exhaust gas flowing in the exhaust passage 3 upstream the catalyst 11 is not higher than a predetermined value, the flow speed of exhaust gas flowing in the exhaust passage 3 upstream the catalyst 11 is increased by operating an air supply device 16 and supplying air to the exhaust passage 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device, and more particularly to an exhaust gas purification device configured to supply active oxygen upstream of an exhaust gas purification catalyst disposed in an exhaust passage of an engine, and a technique for improving exhaust emission. Belonging to the field.

  In general, in a vehicle such as an automobile using fossil fuel such as gasoline as an energy source, the exhaust gas temperature is relatively low for several tens of seconds immediately after the engine is started, and the exhaust gas purification catalyst disposed in the exhaust passage of the engine It is known that hydrocarbon (HC) and carbon monoxide (CO), which are unburned exhaust gas components, are difficult to purify because catalytic metals such as platinum (Pt) and palladium (Pd) are not activated. ing. As one method for improving this, conventionally, a manifold catalyst called “straight catalyzer” in which the catalyst is disposed directly under the exhaust manifold has been widely adopted. However, this method shortens the time until the catalyst temperature rises to the activation temperature, and is not a fundamental solution to the problem.

  Therefore, hydrocarbon adsorbents such as zeolite are used as the material for the manifold catalyst. That is, after the engine is started, when the exhaust gas temperature is relatively low, unburned hydrocarbons discharged from the engine are adsorbed in the pores of the hydrocarbon adsorbent, and when the exhaust gas temperature rises to about 200 ° C, Unburned hydrocarbons adsorbed on the hydrocarbon adsorbent are released and reacted with a catalytic metal activated to some extent at about 200 ° C. However, since aluminosilicate porous materials such as zeolite have the property that the crystal structure tends to collapse at high temperatures, this method has a problem that the purification performance of the catalyst gradually decreases with time. .

In order to cope with this problem, a method of oxidizing and purifying unburned exhaust gas components using active oxygen such as ozone (O ₃ ) without using a hydrocarbon adsorbent such as zeolite has been proposed. For example, Patent Document 1 discloses that ozone, which is active oxygen, is generated by applying a high voltage to air, and this ozone is supplied upstream of the catalyst in the exhaust passage, and one of the HC contained in the exhaust gas. A technique is disclosed in which a part is converted to CO, and this CO is further oxidized to CO ₂ with a catalyst at a later stage.

  Here, in general, active oxygen such as ozone has a strong oxidizing power and has a relatively long life from generation to decomposition at a relatively low temperature of about room temperature. It is considered that supplying active oxygen to the exhaust passage upstream of the catalyst until reaching the activation temperature is an effective method for oxidizing and purifying unburned exhaust gas components of HC and CO.

JP-A-2005-207316 (paragraphs 0046 to 0050)

  As described above, supplying active oxygen such as ozone upstream of the catalyst after the engine is started until the exhaust gas temperature reaches the catalyst activation temperature is effective in oxidizing and purifying unburned exhaust gas components. However, since active oxygen has a finite lifetime from generation to decomposition, for example, the flow rate of exhaust gas is relatively small, for example, at low revolutions and low loads, and therefore When the flow rate of the exhaust gas flowing through the exhaust passage upstream of the catalyst is relatively slow, it takes a relatively long time for the active oxygen supplied to the exhaust passage upstream of the catalyst to reach the catalyst along the exhaust gas flow. As a result, the active oxygen is decomposed before reaching the catalyst, and it becomes difficult to efficiently purify the exhaust gas by the cooperation of the active oxygen and the catalyst.

  The present invention addresses the above-described problems in the exhaust gas purification apparatus configured to supply active oxygen to the exhaust passage upstream of the catalyst when the exhaust gas temperature is equal to or lower than the catalyst activation temperature after the engine is started. Therefore, when the flow rate of the exhaust gas flowing through the exhaust passage upstream of the catalyst is relatively slow, it is an object to suppress the problem that active oxygen is decomposed before reaching the catalyst.

  In order to solve the above problems, the present invention uses the following means.

  That is, the invention according to claim 1 of the present application includes an exhaust gas purification catalyst disposed in an exhaust passage of an engine, and active oxygen supply means capable of supplying active oxygen to an exhaust passage upstream of the exhaust gas purification catalyst. And an exhaust gas temperature detecting means for detecting the temperature of the exhaust gas, and the temperature of the exhaust gas detected by the exhaust gas temperature detecting means after the engine is started is determined by the exhaust gas purification catalyst. An active oxygen supply control means for operating the active oxygen supply means when the temperature is equal to or lower than an activation temperature; an exhaust gas flow rate detection means for detecting a flow rate of exhaust gas flowing through an exhaust passage upstream of the exhaust gas purification catalyst; When the flow rate of the exhaust gas detected by the exhaust gas flow rate detection means is below a predetermined value when the active oxygen supply means is operated by the oxygen supply control means, the upstream side of the exhaust gas purification catalyst Characterized in that the exhaust gas flow velocity increasing means for increasing the flow velocity of the exhaust gas flowing through the exhaust passage is provided.

  Next, an invention according to claim 2 of the present application is the exhaust gas purifying apparatus according to claim 1, wherein air is supplied to an exhaust passage upstream of a portion where the active oxygen supply means supplies active oxygen. A possible air supply means is provided, and the exhaust gas flow rate increasing means increases the flow rate of the exhaust gas by operating the air supply means.

  Next, the invention according to claim 3 of the present application is the exhaust gas purifying apparatus according to claim 1, wherein the active oxygen supply means includes an air feed section that sends air toward the exhaust passage, An active oxygen generation unit that generates active oxygen using the air sent by the air feed unit as a raw material, and the exhaust gas flow rate increasing means increases the air feed amount of the air feed unit to It is characterized by increasing the flow rate of gas.

  Next, the invention according to claim 4 of the present application is the exhaust gas purifying apparatus according to claim 3, wherein when the air feed amount of the air feed unit is increased, the active oxygen of the active oxygen generating unit An active oxygen production rate increasing means for increasing the production rate is provided.

  First, according to the invention described in claim 1, in the exhaust gas purification apparatus provided with active oxygen supply means capable of supplying active oxygen upstream of the exhaust gas purification catalyst disposed in the exhaust passage of the engine, the engine When the exhaust gas temperature is equal to or lower than the catalyst activation temperature after starting the engine, the active oxygen supply means is operated to supply the active oxygen upstream of the catalyst. Until the catalyst activation temperature is reached, the unburned exhaust gas components of HC and CO are effectively oxidized and purified by the cooperation of the active oxygen and the catalyst, and the exhaust gas purification rate is improved.

  That is, more specifically, until the exhaust gas temperature reaches the catalyst activation temperature, a part of the unburned exhaust gas components of HC and CO and a part of the active oxygen are in the exhaust passage upstream of the catalyst. Then, when the remainder of the unburned exhaust gas component of HC and CO and the remainder of the active oxygen flow into the catalyst, they come into contact with each other in the process of diffusing between the catalyst particles in the catalyst layer. A part of the remaining part partially oxidizes the catalytic metal and contributes to the oxidation of HC and CO.

  In addition, when the flow rate of the exhaust gas flowing through the exhaust passage upstream of the exhaust gas purification catalyst is below a predetermined value, the flow rate of the exhaust gas flowing through the exhaust passage upstream of the exhaust gas purification catalyst is increased. Then, the active oxygen supplied to the exhaust passage upstream of the catalyst reaches the catalyst within a relatively short time, and as a result, the active oxygen decomposes before reaching the catalyst, and the active oxygen and the catalyst The problem that it becomes difficult to efficiently purify the exhaust gas through cooperation will be suppressed.

  In that case, according to the invention described in claim 2, the flow rate of the exhaust gas is increased by supplying air to the exhaust passage upstream of the portion where the active oxygen supply means supplies the active oxygen. Thus, the exhaust gas flow rate can be reliably increased by a simple and low-cost method.

  On the other hand, according to the invention described in claim 3, the active oxygen supply means supplies the active oxygen from the air feed section that sends air toward the exhaust passage, and the air sent from the air feed section as a raw material. And a means for supplying air to the exhaust passage since the flow rate of the exhaust gas is increased by increasing the air feed amount of the air feed unit. Need not be provided separately.

  In that case, according to the invention described in claim 4, when the air feed amount of the air feed section is increased, the active oxygen generation rate of the active oxygen generation section is increased. The amount of active oxygen supplied increases, and the purification rate of unburned exhaust gas components is further improved. Hereinafter, the present invention will be described in more detail through the best mode for carrying out the invention.

  FIG. 1 is an overall configuration diagram including a control system of an exhaust gas purification device 10 according to a first embodiment of the present invention. The engine 1 has an intake passage 2 and an exhaust passage 3, and an air flow meter 5 for detecting the amount of intake air and an intake air temperature sensor 6 for detecting the temperature of the intake air are disposed in the intake passage 2, and an exhaust passage is provided. 3, catalytic metals such as platinum (Pt), palladium (Pd), rhodium (Rh), and activated alumina or cerium (Ce) based composite oxide (oxygen storage material) as an oxide carrier supporting these catalytic metals ) And the like are arranged as an exhaust gas purification catalyst.

  The engine 1 is provided with an engine speed sensor 7 for detecting the engine speed.

An ozone supply device 12 is disposed in the exhaust passage 3 upstream from the three-way catalyst 11 as active oxygen supply means. That is, the ozone supply passage 4 joins immediately upstream of the three-way catalyst 11, and the air supply pump 13 for sending air toward the exhaust passage 3 through the passage 4 on the ozone supply passage 4 An ozone generation device (ozonizer) 14 for generating ozone (O ₃ ) as active oxygen using air sent by the pump 13 as a raw material is disposed. For example, the ozone generator 14 generates ozone by silently discharging air.

  Further, an exhaust gas temperature sensor 15 that detects the temperature of the exhaust gas flowing through the exhaust passage 3 upstream of the junction of the ozone supply passage 4 (the portion where the ozone supply device 12 supplies ozone) is provided in the exhaust passage 3. An air supply device 16 for supplying air to the exhaust passage 3 is disposed.

  Here, the air supply port of the air supply device 16 faces the downstream of the exhaust passage 3. Thereby, the air supplied to the exhaust passage 3 from the air supply device 16 acts to reliably increase the flow rate of the exhaust gas flowing through the exhaust passage 3 upstream of the three-way catalyst 11.

  The control unit 20 of the exhaust gas purification device 10 includes an intake air amount signal from the air flow meter 5, an intake air temperature signal from the intake air temperature sensor 6, and an engine speed signal from the engine speed sensor 7. The exhaust gas temperature signal from the exhaust gas temperature sensor 15 is input, and based on the input result, the fuel injection control for the engine 1 and the ozone supply device 12 (that is, the air supply pump 13 and the ozone generation device 14). The ozone supply control for the air supply and the air supply control for the air supply device 16 (that is, the exhaust gas flow rate increase control) are executed.

  FIG. 2 is a flowchart showing an example of a specific control operation performed immediately after the engine 1 is started by the control unit 20 according to the first embodiment. That is, the control unit 20 confirms the cold start in step S11, and then reads various state quantities in step S12. This state quantity includes the intake air quantity, intake air temperature, engine speed, fuel injection quantity, exhaust gas temperature, and the like.

  Next, in step S13, the ozone supply device 12 is operated. That is, ozone is supplied to the exhaust passage 3 upstream of the three-way catalyst 11.

Next, in step S14, space velocity (SV: space velocity) is calculated according to the following equation (1).
SV = (A + B) / volume of catalyst carrier (1)

Here, in the formula (1), A is the intake air volume (V) per unit time detected by the air flow meter 5, the temperature (T1) detected by the intake air temperature sensor 6, and the exhaust gas temperature. This is a value obtained by substituting the temperature (T2) detected by the sensor 15 into the following equation (2).
A = V · (T2 + 273) / (T1 + 273) (2)

  In Equation (1), B is a unit time calculated by calculating the molarity of combustion when it is assumed that the fuel injected into the engine combustion chamber has become gas components of HC, CO, and NOx due to combustion. This is a value obtained by converting the hit exhaust gas volume to a temperature detected by the exhaust gas temperature sensor 15.

  Space velocity is generally an index of the speed at which the exhaust gas purification catalyst processes exhaust gas. In short, the exhaust gas volume that can be processed by the exhaust gas purification catalyst per unit time (for example, per hour) is purified. It is the value divided by the volume of the catalyst. Therefore, as is apparent from FIG. 1, the larger the space velocity, the more the ozone supplied from the ozone supply passage 4 to the exhaust passage 3 by the operation of the ozone supply device 12 in the exhaust gas flow in a shorter time. The exhaust gas purification rate is reliably improved by the cooperation of the three-way catalyst 11 with ozone that has reached the catalyst 11 and has not been decomposed within the lifetime.

  Next, in step S15, it is determined whether or not the space velocity (SV) is equal to or less than a predetermined value. As a result, when the space velocity (SV) is equal to or less than a predetermined value due to, for example, low load and low rotation, the air supply device 16 is operated in step S16. That is, air is supplied to the exhaust passage 3 upstream of the three-way catalyst 11. As a result, as described above, the flow rate of the exhaust gas flowing through the exhaust passage 3 upstream of the three-way catalyst 11 is increased by the air supplied from the air supply device 16 to the exhaust passage 3.

  On the other hand, when the space velocity (SV) is larger than the predetermined value in step S15, the process proceeds to step S17 without increasing the flow rate of the exhaust gas.

  Next, in step S17, it is determined whether or not the exhaust gas temperature T is equal to or lower than the catalyst activation temperature TH. As a result, the steps S12 to S16 are repeated while the exhaust gas temperature T is equal to or lower than the catalyst activation temperature TH. That is, ozone supply (S13) and air supply (S16: only when necessary) are continued.

  Then, when the exhaust gas temperature T becomes higher than the catalyst activation temperature TH, the process proceeds to step S18 to stop the supply of ozone, and the process proceeds to step S19 to stop the supply of air (only when it has been performed). Then, this control ends.

  As described above, the exhaust gas purification apparatus 10 according to the present embodiment has an ozone supply device 12 (that is, an air supply pump 13 and an ozone generation device 14) upstream of the three-way catalyst 11 disposed in the exhaust passage 3 of the engine 1. ) Is configured to be able to supply ozone. After the engine 1 is started (YES in step S11), when the exhaust gas temperature T is equal to or lower than the catalyst activation temperature TH (YES in step S17), the ozone supply device 12 is operated (step S13), and ozone is supplied. Since the gas is supplied upstream of the three-way catalyst 11, the unburned exhaust gas components of HC and CO are separated from ozone and three until the exhaust gas temperature T reaches the catalyst activation temperature TH after the engine 1 is started. By cooperating with the original catalyst 11, it is effectively oxidized and purified, and the exhaust gas purification rate is improved.

  In addition, when the flow velocity (space velocity SV) of the exhaust gas flowing through the exhaust passage 3 upstream of the three-way catalyst 11 is below a predetermined value (YES in step S15), the exhaust passage 3 upstream of the three-way catalyst 11 is passed through. Since the flow velocity of the flowing exhaust gas is increased (step S16), the ozone supplied to the exhaust passage 3 upstream of the three-way catalyst 11 by the operation of the ozone supply device 12 is converted into the three-way catalyst within a relatively short time. As a result, ozone is decomposed by the time it reaches the three-way catalyst 11, and it becomes difficult to efficiently purify the exhaust gas by cooperation of ozone and the three-way catalyst 11. Will be suppressed.

  In that case, the flow rate of the exhaust gas is increased by the air supply device 16 supplying air to the exhaust passage 3 upstream from the portion where the ozone supply device 12 supplies ozone (the confluence of the ozone supply passage 4). Therefore, the flow rate of the exhaust gas can be reliably increased by a simple and low-cost method.

  Next, a second embodiment of the present invention will be described. However, the description of the same or similar parts as those in the first embodiment will be omitted, and only the characteristic parts of the second embodiment will be described. The same reference numerals are used for the same or similar components as those in the first embodiment.

  FIG. 3 is an overall configuration diagram including a control system of the exhaust gas purifying apparatus 10 according to the second embodiment of the present invention. The difference from FIG. 1 is that an air supply device 16 for supplying air to the exhaust passage 3 is not provided.

  The control unit 20 of the exhaust gas purifying device 10 includes an intake air amount signal from the air flow meter 5, an intake air temperature signal from the intake air temperature sensor 6, and an engine speed from the engine speed sensor 7. The number signal and the exhaust gas temperature signal from the exhaust gas temperature sensor 15 are input, and based on the input result, the fuel injection control for the engine 1 and the ozone supply device 12 (that is, the air supply pump 13 and the ozone generation device). 14) and the exhaust gas flow rate increase control for the ozone supply device 12 (that is, the air supply pump 13 and the ozone generation device 14).

  FIG. 4 is a flowchart showing an example of a specific control operation performed immediately after the engine 1 is started by the control unit 20 according to the second embodiment. Steps S21 to S25 and S28 are the same as steps S11 to S15 and S17 of FIG.

  In the second embodiment, when the space velocity (SV) is equal to or less than a predetermined value in step S25, the air supply pump 13 of the ozone supply device 12 is accelerated in step S26. That is, the amount of air sent toward the exhaust passage 3 through the ozone supply passage 4 is increased. As a result, the amount of air supplied from the ozone supply passage 4 to the exhaust passage 3 increases, and the flow rate of the exhaust gas flowing through the exhaust passage 3 upstream of the three-way catalyst 11 increases.

  Next, in step S27, the ozone generation rate in the ozone generation device 14 of the ozone supply device 12 is increased. That is, the ozone generation rate by the ozone generation device 14 is increased in step with the increase in the air feed amount by the air supply pump 13. This can be achieved, for example, by increasing the applied voltage when silently discharging air.

  In the second embodiment, in step S28, when the exhaust gas temperature T becomes higher than the catalyst activation temperature TH, the process proceeds to step S29 and the ozone supply device 12 (that is, the air supply pump 13 and the ozone). The generator 14) is stopped. That is, the supply of ozone to the exhaust passage 3, the increase of the exhaust gas flow rate (only when it is performed) and the increase of the ozone generation rate (only when it is performed) are stopped, and this control is finished.

  As described above, in the second embodiment, the ozone supply device 12 sends the air toward the exhaust passage 3 and the air supplied from the air supply pump 13 is used as a raw material for ozone. The ozone generation device 14 for generating the air supply pump 13 increases the air feed rate of the air supply pump 13 (step S26), thereby increasing the flow rate of the exhaust gas. It is not necessary to separately provide a means for supplying to the air supply 3 (for example, the air supply device 16 of the first embodiment).

  Then, when the air feed amount of the air supply pump 13 is increased, the ozone generation rate of the ozone generator 14 is increased (step S27), so that the amount of ozone supplied to the exhaust passage 3 increases. The purification rate of unburned exhaust gas components will be further improved.

  FIG. 5 is a graph showing an experimental result of the exhaust gas purification rate performed by changing the flow rate of the exhaust gas.

That is, an exhaust gas purification performance test was conducted by passing a simulated exhaust gas through an exhaust gas purification catalyst generally used in gasoline engines. The catalyst used had a total amount of catalyst noble metal of 7.0 g / L, and the breakdown was Pt: Pd: Rh in a mass ratio of 1: 30: 2. Further, Pd-supporting Al ₂ O ₃ was 100 g / L, Rh-supporting OSC material (oxygen storage material containing ceria) was 70 g / L, and Pt-supporting Al ₂ O ₃ was 60 g / L.

The composition of the simulation gas used was propylene (C ₃ H ₆ ) 700 ppmC, ozone (O ₃ ) 0.3 vol%, oxygen (O ₂ ) 0.7 vol%, and the rest nitrogen.

  The flow rate of the simulated gas is 20 L / min (corresponding to 48,000 / h in terms of space velocity SV) by supplying air in the case of Experimental Example A, and the same air supply in the case of Experimental Example B. 15 L / min (equivalent to 36,000 / h when converted to space velocity SV), in the case of Experimental Example C, 10 L / min (equivalent to 24,000 / h when converted to space velocity SV) without air supply did.

  The temperature of the simulated gas started from 70 ° C. (cold start) and was raised at 10 ° C./min.

  The results are shown in FIG. In FIG. 5, the vertical axis represents the propylene concentration in the simulated gas after passing through the catalyst. As can be seen, the exhaust gas purification rate decreases as the simulated gas flow rate decreases. That is, in the experimental examples A and B in which the flow rate of the simulated gas or the space velocity SV is increased by supplying the air, the exhaust gas purification rate increases steadily as the simulated gas temperature and thus the catalyst temperature increase. In Experiment A where the simulated gas flow rate is the highest, the exhaust gas purification rate reaches approximately 100% when the simulated gas temperature reaches about 170 ° C., and then in Experiment B where the simulated gas flow rate is the highest, When the gas temperature reached approximately 180 ° C., the exhaust gas purification rate reached approximately 100%. In contrast to this, in Experiment C where air supply was not performed and the flow speed of the simulated gas was the lowest, the purification rate increased until the simulated gas temperature was approximately 140 ° C., but thereafter the purification rate was reversed. The rate declined and the purification rate never reached 100%. This is because the lifetime of ozone is rapidly shortened when the ambient temperature is about 140 to 150 ° C. or more near the catalyst activation temperature, and the exhaust gas purification efficiency due to cooperation between ozone and the catalyst is drastically reduced. it is conceivable that.

  Therefore, depending on the conditions, even if the exhaust gas flow rate is not more than a predetermined value (in the case of Experimental Example C), the exhaust gas flow rate is not always increased (steps S15, S16 and FIG. 2). Until the exhaust gas temperature rises to a predetermined temperature (about 140 to 150 ° C. in this experimental example) or higher, the flow rate of the exhaust gas is not increased and the exhaust gas temperature is kept at the predetermined temperature (see steps S25 and S26 in FIG. 4). Same as above) The flow rate of the exhaust gas may be increased at the above-mentioned stage.

  The above embodiment is the best embodiment of the present invention, but it goes without saying that various modifications and changes may be made without departing from the scope of the claims. For example, in the above-described embodiment, the exhaust gas temperature is directly detected by the exhaust gas temperature sensor 15 disposed in the exhaust passage 3, but not limited to this, the engine load (intake air amount), the engine speed, etc. It is also possible to detect indirectly based on the operating state of the engine 1.

  As described above in detail with reference to specific examples, the present invention suppresses the problem that active oxygen decomposes before reaching the catalyst even when the flow rate of the exhaust gas flowing through the exhaust passage upstream of the catalyst is slow. Since it is a possible technology, it is a wide range of industries in the technical field of exhaust gas purification devices, particularly exhaust gas purification devices configured to be able to supply active oxygen upstream of an exhaust gas purification catalyst disposed in an exhaust passage of an engine. The above availability is expected.

1 is an overall configuration diagram including a control system for an exhaust gas purifying apparatus according to a first embodiment of the present invention. It is a flowchart which shows an example of the concrete control operation which the control unit which concerns on 1st Embodiment performs immediately after starting of an engine. It is a whole block diagram containing the control system of the exhaust-gas purification apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows an example of the specific control operation which the control unit which concerns on 2nd Embodiment performs immediately after starting of an engine. It is a graph which shows the experimental result of the exhaust gas purification rate performed by changing the flow rate of exhaust gas.

Explanation of symbols

1 Engine 3 Exhaust passage 10 Exhaust gas purification device 11 Exhaust gas purification catalyst (three-way catalyst)
12 Ozone supply device (active oxygen supply means)
13 Air supply pump (air feed part)
14 Ozone generator (active oxygen generator)
15 Exhaust gas temperature sensor (exhaust gas temperature detection means)
16 Air supply device (air supply means)
20 Control unit (active oxygen supply control means, exhaust gas flow rate detection means, exhaust gas flow rate increase means, active oxygen production rate increase means)

Claims (4)

An exhaust gas purification catalyst disposed in the exhaust passage of the engine;
An exhaust gas purification device having active oxygen supply means capable of supplying active oxygen to an exhaust passage upstream of the exhaust gas purification catalyst,
Exhaust gas temperature detecting means for detecting the temperature of the exhaust gas;
Active oxygen supply control means for operating the active oxygen supply means when the temperature of the exhaust gas detected by the exhaust gas temperature detection means is equal to or lower than the activation temperature of the exhaust gas purification catalyst after the engine is started;
Exhaust gas flow rate detection means for detecting the flow rate of exhaust gas flowing through the exhaust passage upstream of the exhaust gas purification catalyst;
When the active oxygen supply means is operated by the active oxygen supply control means, and the exhaust gas flow rate detected by the exhaust gas flow rate detection means is below a predetermined value, the exhaust gas flowing through the exhaust passage upstream of the exhaust gas purification catalyst And an exhaust gas flow rate increasing means for increasing the flow rate of the exhaust gas. The exhaust gas purification device according to claim 1,
An air supply means capable of supplying air to an exhaust passage upstream of a site where the active oxygen supply means supplies active oxygen;
The exhaust gas purification apparatus according to claim 1, wherein the exhaust gas flow rate increasing means increases the flow speed of the exhaust gas by operating the air supply means. The exhaust gas purification device according to claim 1,
The active oxygen supply means has an air feed section that sends air toward the exhaust passage, and an active oxygen generation section that generates active oxygen using the air sent by the air feed section as a raw material,
The exhaust gas flow rate increasing means increases the flow rate of the exhaust gas by increasing the air feed amount of the air feed section. An exhaust gas purification device according to claim 3,
An exhaust gas purifying apparatus, comprising: an active oxygen production rate increasing means for increasing an active oxygen production rate of the active oxygen production unit when an air feed amount of the air feed unit is increased.

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