JP2010101303A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine regenerating a PM filter while reducing CO emission, even if an oxidation catalyst is inactive. <P>SOLUTION: An oxidation catalyst 14, a DPF 16, and an ozone generator 18 are disposed in an exhaust passage 12 from upstream to downstream in this order. A bypass passage 22 is connected to an upstream side of the oxidation catalyst 14. A CO adsorbent 24 is disposed in the bypass passage 22. In controlling regeneration of the DPF 16, ozone is supplied to the DPF 16 in a state where an exhaust shutoff valve 28 is closed and a backward flow open valve 30 is opened. Thus, when PM in the DPF 16 is oxidized by the ozone, gas generated by the reaction if fed backward in the exhaust passage 12, thus allowing CO in the gas to be adsorbed by the adsorbent 24. Meanwhile, in controlling desorption of the adsorbent 24, exhaust gas is introduced in the bypass passage 22, and CO desorbed from the adsorbent 24 is purified by the oxidation catalyst 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device suitably used for an internal combustion engine, and more particularly to an exhaust emission purification device for an internal combustion engine configured to use active oxygen.

  As a prior art, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2007-77971), an exhaust gas purification device for an internal combustion engine including a DPF (Diesel Particulate Filter) and an ozone supply device is known. Yes. According to this exhaust gas purification apparatus, particulate matter (PM) collected in the DPF can be oxidized by ozone to regenerate the DPF.

JP 2007-77971 A

  By the way, in the prior art mentioned above, it is set as the structure which oxidizes PM by supplying ozone to DPF. However, when ozone is supplied to the DPF at a low temperature, for example, before warming up the internal combustion engine, carbon monoxide (CO) is likely to be generated due to incomplete combustion of PM. For this reason, in the prior art, when the regeneration process of the DPF is performed at a low temperature, there is a problem that exhaust emission deteriorates due to generation of CO.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to perform regeneration processing of a PM filter while suppressing CO emission even when the oxidation catalyst is in a low temperature state. An object of the present invention is to provide an exhaust emission control device for an internal combustion engine capable of improving exhaust emission.

The first invention is provided in an exhaust passage through which exhaust gas of an internal combustion engine flows, and an oxidation catalyst that purifies unpurified components in the exhaust gas by oxidation,
A PM filter that is provided in the exhaust passage downstream of the oxidation catalyst and collects particulate matter in the exhaust gas;
Active oxygen supply means for supplying active oxygen to the PM filter;
A CO adsorbent disposed or connected to the exhaust passage upstream of the oxidation catalyst and adsorbing carbon monoxide in the gas;
Direction switching for switching the gas flow direction so that the gas in the exhaust passage flows in the reverse direction from the PM filter toward the CO adsorbent when the active oxygen is supplied to the PM filter by the active oxygen supply means. Means,
A regeneration control means for driving the active oxygen supply means and the direction switching means to circulate active oxygen in the reverse direction when performing a regeneration process for oxidizing the PM in the PM filter;
It is characterized by providing.

A second invention is a passage that bypasses a part of the exhaust passage on the upstream side of the oxidation catalyst, and a bypass passage in which the CO adsorbent is disposed;
Bypass switching means for switching a flow path of the exhaust gas between a part of the exhaust passage and the bypass passage;
Desorption control means for causing exhaust gas to flow through the bypass passage by the bypass switching means when performing desorption processing for desorbing carbon monoxide from the CO adsorbent;
It is set as the structure provided with.

3rd invention is equipped with the pressure detection means which detects the pressure difference of the upstream of the said PM filter, and a downstream,
The regeneration control means is configured to determine whether to perform regeneration processing of the PM filter according to the temperature of the exhaust gas and the pressure difference.

  According to a fourth aspect, the regeneration control means regenerates the PM filter when the temperature of the exhaust gas is lower than the thermal decomposition temperature of the active oxygen and the pressure difference is greater than a predetermined reference determination value. It is set as the structure which performs a process.

  According to a fifth aspect of the invention, the regeneration control means is configured to execute the regeneration process of the PM filter when the internal combustion engine enters a stopped state or a low output operation state.

6th invention is equipped with the temperature acquisition means to acquire the temperature of the said oxidation catalyst,
The desorption control means is configured to execute the desorption processing of the CO adsorbent when at least the temperature of the oxidation catalyst is equal to or higher than the activation temperature of the catalyst.

  According to the seventh invention, the desorption temperature at which carbon monoxide is desorbed from the CO adsorbent is set to be higher than the activation temperature at which the oxidation catalyst is activated.

According to an eighth aspect of the invention, the direction switching means includes an exhaust cutoff valve that opens and closes the exhaust passage on the downstream side of the PM filter,
The regeneration control means is configured to supply active oxygen to the PM filter by the active oxygen supply means with the exhaust shutoff valve closed when performing regeneration processing of the PM filter.

According to a ninth aspect of the invention, the direction switching means includes a reverse flow release valve that opens and shuts off a portion of the CO adsorbent from which the gas flowing in the reverse direction flows out.
The regeneration control unit is configured to open the backflow release valve when performing regeneration processing of the PM filter.

  According to a tenth invention, the active oxygen supply means supplies ozone as the active oxygen.

An eleventh invention is provided in an exhaust passage through which exhaust gas of an internal combustion engine flows, and an oxidation catalyst that purifies unpurified components in the exhaust gas by oxidation,
A PM filter that is provided in the exhaust passage downstream of the oxidation catalyst and collects particulate matter in the exhaust gas;
Active oxygen supply means for supplying active oxygen to the PM filter;
Gas collecting means capable of collecting the gas flowing out of the PM filter and supplying the gas to the oxidation catalyst;
When the active oxygen is supplied to the PM filter, the collection control means for collecting the gas flowing out from the PM filter in the gas collection means,
Supply control means for supplying the gas collected by the gas collecting means to the oxidation catalyst when the temperature of the exhaust gas rises above a predetermined value;
It is characterized by providing.

  According to a twelfth aspect of the invention, the collecting means is a CO adsorbent that adsorbs carbon monoxide flowing out of the PM filter.

According to a thirteenth invention, the gas collecting means is
A gas storage unit connected to the exhaust passage;
An actuator for causing the gas to flow into and out of the gas storage unit;
It is set as the structure provided with.

A fourteenth aspect of the invention includes a passage closing means capable of forming a closed passage blocked from the outside by closing a part of the exhaust passage,
At least the PM filter, the active oxygen supply means and the gas collection means are connected to the closed passage.

  According to the first invention, when the regeneration process of the PM filter is performed, the flow direction of the gas flowing in the exhaust passage can be switched to the reverse direction by the direction switching means. In this state, active oxygen can be supplied to the PM filter by the active oxygen supply means, and the PM collected in the filter can be oxidized with active oxygen. The gas generated by this oxidation reaction can be caused to flow into the CO adsorbent through the oxidation catalyst, and the CO in the gas can be adsorbed by the CO adsorbent. Thereby, even if the oxidation catalyst is not activated at a low temperature or the like, it is possible to reliably prevent CO generated when the PM is oxidized from being discharged to the outside.

  Therefore, even when the internal combustion engine is stopped or cold started, the regeneration of the PM filter can be freely performed while suppressing CO emission, and the exhaust emission at low temperatures can be improved. Further, after the internal combustion engine is warmed up, CO can be desorbed from the CO adsorbent by heat from, for example, exhaust gas or a heater. At this time, according to the direction switching means, the gas in the exhaust passage is set to flow in the forward direction from the upstream side to the downstream side, and the CO desorbed from the CO adsorbent is purified by the downstream oxidation catalyst. be able to.

  Thus, according to the first aspect of the present invention, it is possible to easily perform the regeneration process of the PM filter and the desorption process of the CO adsorbent only by switching the gas flow direction. In addition, the effects described above can be obtained without arranging a PM filter having a relatively large heat capacity on the upstream side of the oxidation catalyst. As a result, when the internal combustion engine is started, the oxidation catalyst can be quickly activated by the exhaust heat, and the exhaust emission can be further improved.

  According to the second aspect of the present invention, when the CO adsorbent is desorbed, the exhaust gas can be circulated through the bypass passage by the bypass switching means and can be introduced into the CO adsorbent. As a result, CO can be separated from the CO adsorbent by the exhaust heat, and this CO can be joined to the exhaust passage and purified by the oxidation catalyst. Further, in the normal exhaust state where the desorption treatment is not executed, the exhaust gas does not pass through the CO adsorbent, so that the exhaust heat can be efficiently transmitted to the oxidation catalyst. Therefore, the activation of the oxidation catalyst can be accelerated at the time of starting or the like.

  According to the third invention, the pressure difference between the upstream side and the downstream side of the PM filter increases as the amount of PM collected in the filter increases. Further, when the temperature of the exhaust gas is high, the active oxygen supplied to oxidize PM is easily decomposed by heat. For this reason, the regeneration control means can execute the regeneration process of the PM filter at an appropriate timing according to the pressure difference and the temperature of the exhaust gas.

  According to the fourth invention, the regeneration control means can determine, for example, that the amount of PM that needs to be processed has been collected in the PM filter by comparing the pressure difference with the reference determination value. When this determination is made and the temperature environment is such that the active oxygen is not thermally decomposed, the regeneration process of the PM filter can be executed. Thereby, the PM filter can be efficiently regenerated.

  According to the fifth aspect of the invention, when the internal combustion engine is stopped or in a low output operation state such as an idle operation, the temperature of the exhaust gas is often lower than the thermal decomposition temperature of active oxygen. Therefore, in this case, the PM filter can be efficiently regenerated. Further, for example, in a hybrid vehicle using both an internal combustion engine and an electric motor, the internal combustion engine may be stopped when traveling by the electric motor. Therefore, the regeneration process of the PM filter can be smoothly performed using this stop period.

  According to the sixth aspect of the invention, the desorption control means can perform the CO adsorbent desorption process at least when the temperature of the oxidation catalyst is equal to or higher than the activation temperature of the catalyst. Thereby, CO desorbed from the CO adsorbent can be reliably purified by the activated oxidation catalyst.

  According to the seventh invention, the desorption temperature of the CO adsorbent can be set higher than the activation temperature of the oxidation catalyst. Thereby, for example, when CO is desorbed from the CO adsorbent due to exhaust heat or the like, since the oxidation catalyst has already been activated, the desorbed CO can be reliably purified by the oxidation catalyst. In addition, as a starting condition for the desorption process, for example, it is only necessary to determine whether or not the exhaust gas temperature is equal to or higher than the desorption temperature. Therefore, the control can be simplified.

  According to the eighth aspect, when the regeneration process of the PM filter is performed, the exhaust passage can be closed on the downstream side of the PM filter by the exhaust cutoff valve. Thereby, the gas etc. produced by the oxidation reaction in the PM filter can be circulated in the reverse direction toward the upstream CO adsorbent.

  According to the ninth aspect, when the regeneration process of the PM filter is performed, the backflow release valve can be opened. Thereby, for example, a portion where the gas flowing in the reverse direction in the exhaust passage flows out of the CO adsorbent can be opened to the atmosphere. Therefore, the gas flowing out from the PM filter can smoothly flow into the CO adsorbent.

  According to the tenth aspect, by using ozone as active oxygen, the effects of the first to ninth aspects can be exhibited more remarkably.

  According to the eleventh aspect of the invention, when the regeneration process of the PM filter is performed, CO generated by the reaction between PM and active oxygen and excess active oxygen that does not contribute to the reaction are collected by the gas collecting means. be able to. For this reason, according to the collection control means, even if the oxidation catalyst is not activated at a low temperature or the like, it is possible to reliably prevent CO and active oxygen generated during oxidation of PM from being discharged to the outside. Then, according to the supply control means, for example, when the oxidation catalyst is activated by an increase in the temperature of the exhaust gas, the gas collected by the gas collection means can be supplied to the oxidation catalyst. As a result, the oxidation catalyst can stably purify CO and active oxygen. Accordingly, as in the case of the first invention, the regeneration process of the PM filter can be freely performed while suppressing the emission of CO even when the internal combustion engine is stopped or cold start, and the exhaust emission at a low temperature can be performed. Can be improved.

  According to the twelfth invention, CO and active oxygen generated during oxidation of PM can be adsorbed by the CO adsorbent. Therefore, the configuration of the entire system including the gas collecting means can be simplified.

  According to the thirteenth aspect, when the regeneration process of the PM filter is performed, CO and active oxygen can be collected in the gas storage unit by operating the actuator of the gas collecting means in the gas inflow direction. When purifying the collected gas, the actuator is operated in the gas outflow direction to release CO and active oxygen in the gas storage unit from the gas storage unit, and direct these gases toward the oxidation catalyst. Can be supplied.

  According to the fourteenth aspect, the passage closing means can form a closed passage by closing a part of the exhaust passage when performing the regeneration process of the PM filter. Thus, the active oxygen supplied to the closed passage by the active oxygen supply means can be efficiently flowed into the PM filter by utilizing the sealing property of the closed passage. Further, by utilizing the sealing property of the closed passage, CO and excess active oxygen that have flowed out of the PM filter can be efficiently collected by the gas collecting means.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. In Embodiment 1 of this invention, it is operation | movement explanatory drawing which shows the state which implemented the regeneration control of DPF. It is a characteristic diagram which shows the relationship between the oxidation rate of PM by ozone and various catalysts, and inflow gas temperature. It is a characteristic diagram which shows the effect at the time of processing the exhaust gas at the time of PM oxidation with CO adsorption material. In Embodiment 1 of this invention, it is operation | movement explanatory drawing which shows the state which implemented desorption control of CO adsorbent. In Embodiment 1 of this invention, it is explanatory drawing which compares and shows the desorption temperature of CO adsorption material, and the activation temperature of an oxidation catalyst. In Embodiment 1 of this invention, it is a flowchart of the control performed by ECU. It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 2 of this invention. It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 3 of this invention. It is operation | movement explanatory drawing which shows the gas collection control performed at the time of reproduction | regeneration of DPF. It is operation | movement explanatory drawing which shows collection gas purification control. In Embodiment 3 of this invention, it is a flowchart of the control performed by ECU. It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 4 of this invention. In Embodiment 4 of this invention, it is a flowchart of the control performed by ECU.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. First, FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. As shown in FIG. 1, the system according to the present embodiment includes an internal combustion engine 10 composed of, for example, a diesel engine. The internal combustion engine 10 includes an intake passage (not shown) that sucks intake air into the cylinder, and an exhaust passage 12 through which exhaust gas discharged from the cylinder flows.

In the exhaust passage 12, an oxidation catalyst 14, a DPF 16, and an ozone generator 18 are provided. The oxidation catalyst 14 oxidizes carbon monoxide (CO) and hydrocarbons (HC), which are unburned components (incomplete combustion components) in the exhaust gas, to convert them into CO ₂ , H ₂ O, etc. Has the function of purifying unburned components. As the catalyst component of the oxidation catalyst 14, for example, an oxide carrier carrying a transition metal is used. Specific examples of the catalyst component include Pt / CeO ₂ , Mn / CeO ₂ , Fe / CeO ₂ , Ni / CeO ₂ , and Cu / CeO ₂ . The DPF 16 constitutes the PM filter of the present embodiment and is provided on the downstream side of the oxidation catalyst 14. And DPF16 purifies PM by collecting the particulate matter (PM) in exhaust gas, and burning this (oxidizing).

The ozone generator 18 constitutes the active oxygen supply means of the present embodiment, and includes, for example, an ozone supply port 20 connected to the exhaust passage 12 on the downstream side of the DPF 16. The ozone generator 18 supplies ozone (O ₃ ) from the downstream side to the DPF 16, for example. As will be described later, this ozone can purify PM collected in the DPF 16 even at a low temperature. Further, as the ozone generator 18, a form in which ozone is generated while flowing dry air or oxygen as a raw material in a discharge tube to which a high voltage can be applied, or any other type can be used. In this case, the dry air or oxygen as a raw material is a gas such as outside air taken from the outside of the exhaust passage 12.

On the other hand, a bypass passage 22 that bypasses a part of the exhaust passage 12 on the upstream side of the oxidation catalyst 14 is connected to the exhaust passage 12. The bypass passage 22 is provided with a CO adsorbent 24 that adsorbs CO in the gas. The CO adsorbent 24 constitutes the gas collecting means of the present embodiment, and can collect CO in the gas flowing out from the DPF 16 and supply this CO to the oxidation catalyst 14 as will be described later. . The CO adsorbent 24 is made of an oxide carrier (eg, zeolite, CeO ₂ , Al ₂ O _3, etc.) carrying a transition metal (eg, Cu, Ag, etc.) that tends to be in an oxidized state. For this reason, the CO adsorbent 24 has a function of adsorbing CO in the gas even at a low temperature such as before warming up the internal combustion engine. The adsorbed CO is desorbed from the CO adsorbent 24 when the temperature becomes higher than the desorption temperature described later. In the present specification, the term “adsorption” includes all concepts similar to “occlusion”, “absorption”, “retention”, and the like.

  The bypass passage 22 is provided with a bypass switching valve 26 as bypass switching means. The bypass switching valve 26 is constituted by an electromagnetically driven three-way valve driven by an ECU 40 described later. The bypass switching valve 26 switches the exhaust gas flow path between a part of the exhaust passage 12 and the bypass passage 22.

  In addition, the system of the present embodiment includes an exhaust cutoff valve 28 and a backflow release valve 30 configured by, for example, an electromagnetic valve. These valves 28 and 30 constitute direction switching means for switching the flow direction of the gas flowing in the exhaust passage 12 between the forward direction and the reverse direction. Here, the forward direction is a flow direction when the exhaust gas flows from the oxidation catalyst 14 (or the CO adsorbent 24) toward the DPF 16. Further, the reverse direction is a flow direction when a gas containing ozone passes from the DPF 16 through the oxidation catalyst 14 and further flows toward the CO adsorbent 24 as shown in FIG.

  The exhaust cutoff valve 28 is provided in the exhaust passage 12 on the downstream side of the DPF 16 and the ozone supply port 20, and opens and closes the exhaust passage 12 at this position. For this reason, in a state where the exhaust cutoff valve 28 is closed, ozone supplied to the exhaust passage 12 by the ozone generator 18 flows in the reverse direction through the exhaust passage 12 from the DPF 16 toward the CO adsorbent 24. On the other hand, the backflow release valve 30 is provided, for example, in a portion of the bypass passage 22 that is located upstream of the CO adsorbent 24, and at this position, the bypass passage 22 is opened and closed from the outside. That is, the backflow release valve 30 opens the portion of the CO adsorbent 24 through which the gas flowing in the reverse direction flows out to the atmosphere. For this reason, the gas flowing in the reverse direction in the exhaust passage 12 smoothly flows into the CO adsorbent 24 in a state in which the backflow release valve 30 is opened.

  Furthermore, the system of the present embodiment includes a sensor system including a temperature sensor 32, a pressure sensor 34, and the like, and an ECU (Electronic Control Unit) 40 that controls the operation of the internal combustion engine 10. The temperature sensor 32 constitutes the temperature acquisition means of the present embodiment, and detects the temperature (bed temperature) of the oxidation catalyst 14. In the present invention, for example, the temperature of the exhaust gas may be detected around the oxidation catalyst 14 using a temperature sensor, and the bed temperature of the catalyst may be calculated or estimated from the detection result.

  On the other hand, the pressure sensor 34 constitutes the pressure detecting means of the present embodiment, and detects the pressure difference of the exhaust pressure between the upstream side and the downstream side of the DPF 16. This pressure difference increases as the amount of PM trapped in the DPF 16 increases. In addition, since the exhaust pressure on the upstream side of the DPF 16 also increases in accordance with the amount of collected PM, the upstream exhaust pressure may be detected by the pressure sensor 34 in the present invention.

  In addition to these sensors 32 and 34, the sensor system includes a crank angle sensor for detecting the crank angle of the internal combustion engine 10, an air flow meter for detecting the intake air amount, a water temperature sensor for detecting the temperature of the cooling water, and the like. include. On the other hand, the internal combustion engine 10 includes various actuators including a fuel injection valve, an ignition plug, an ozone generator 18, a bypass switching valve 26, an exhaust cutoff valve 28, a backflow release valve 30, and the like. The ECU 30 controls each actuator while detecting the operating state of the internal combustion engine using the sensor system. This control includes normal exhaust control described below, DPF 16 regeneration control, and CO adsorbent 24 desorption control.

(Normal exhaust control)
Normal exhaust control is performed when the regeneration control or desorption control is not required. In this control, as shown in FIG. 1, the bypass switching valve 26 is held at the normal position, the exhaust cutoff valve 28 is opened, and the backflow opening valve 30 is closed. As a result, the exhaust gas flows through the exhaust passage 12 in the forward direction. At this time, HC, CO, etc. in the exhaust gas are oxidized by the oxidation catalyst 14, and PM in the exhaust gas is collected by the DPF 16, so that the exhaust gas can be purified. Further, in the present embodiment, the oxidation catalyst 14 is arranged on the upstream side of the DPF 16. Thereby, the oxidation catalyst 14 can be activated as early as possible by the exhaust heat.

(DPF regeneration control)
In the regeneration control, the PM collected in the DPF 16 is oxidized and removed by ozone to regenerate its performance. In the present embodiment, regeneration control of the DPF 16 is performed when a predetermined regeneration condition is satisfied. As an example of this regeneration condition, (1) when the internal combustion engine is in a stopped state or in a low output operation state such as an idle operation, (2) the temperature of the exhaust gas is a thermal decomposition temperature of ozone (for example, And (3) when the pressure difference between the upstream side and the downstream side of the DPF 16 during operation of the internal combustion engine is greater than a predetermined reference determination value. Here, the reference determination value of the pressure difference is obtained in advance as a pressure difference when the amount of collected PM in the DPF 16 becomes excessive, for example, and stored in the ECU 40. Further, the temperature of the exhaust gas may be directly detected by a temperature sensor or the like, but can be estimated and calculated according to the operation state (engine speed, load, etc.) of the internal combustion engine.

  When the above condition (1) is satisfied, the temperature of the exhaust gas is often lower than the thermal decomposition temperature of ozone. In this case, the ozone supplied to oxidize PM can be prevented from being decomposed by heat, and the oxidation process of PM can be performed efficiently. Further, when the condition (2) is established, it is possible to reliably prevent the thermal decomposition of ozone. Furthermore, when the condition (3) is satisfied, it can be determined that it is a timing at which regeneration control is necessary.

  Therefore, for example, when all of the conditions (1), (2), and (3) are satisfied, the ECU 40 determines that the regeneration condition is satisfied and performs regeneration control. In addition, the regeneration control is ended when a certain time elapses, for example, when it is determined that the PM in the DPF 16 is sufficiently oxidized. In the present invention, for example, even if the condition (1) is not satisfied, it may be determined that the reproduction condition is satisfied when the conditions (2) and (3) are satisfied. In the case of simplifying the control, for example, it may be determined that the reproduction condition is satisfied only by the condition (1) being satisfied without performing the determination of the conditions (2) and (3). .

  FIG. 2 is an operation explanatory diagram showing a state in which DPF regeneration control is performed in Embodiment 1 of the present invention. As shown in FIG. 2, in the regeneration control, the exhaust cutoff valve 28 is closed and the exhaust passage 12 is closed on the downstream side of the ozone supply port 20. Further, the reverse flow release valve 30 is opened, and the position where the gas flowing in the reverse direction through the bypass passage 22 flows out of the CO adsorbent 24 is opened to the atmosphere. When the ozone generator 18 is operated and ozone is supplied to the downstream side of the DPF 16, this ozone flows in the reverse direction through the exhaust passage 12 because the exhaust cutoff valve 28 is closed. Oxidize.

Thereby, in the DPF 16, gases such as CO ₂ , CO, and O ₂ are generated by the reaction between ozone and PM, and this gas flows out from the DPF 16 toward the oxidation catalyst 14. The gas that has passed through the oxidation catalyst 14 flows into the bypass passage 22 and passes through the CO adsorbent 24 because the backflow release valve 30 is open to the atmosphere. At this time, CO in the gas is adsorbed by the CO adsorbent 24, and other components flow out of the CO adsorbent 24 and are released to the outside.

Here, the effect of combining the oxidation of PM with ozone and the CO adsorbent will be described. First, FIG. 3 is a characteristic diagram showing the relationship between the oxidation rate of PM by ozone and various catalysts and the inflow gas temperature. “NO ₂ ” in FIG. 3 is a PM oxidation method using NO ₂ , and “solid catalyst” is a general-purpose solid catalyst in which, for example, a metal is supported on ceramics. As shown in FIG. 3, when ozone is used, PM can be efficiently oxidized even in a low temperature state (eg, a temperature of 200 ° C. or lower) in which PM is hardly oxidized.

  FIG. 4 is a characteristic diagram showing the effect when the exhaust gas during PM oxidation is treated with a CO adsorbent. FIG. 4 (a) measures the CO concentration in the gas flowing out from the DPF while oxidizing the PM in the DPF with ozone. On the other hand, FIG. 4 (b) measures the CO concentration in the gas flowing out from the DPF through the CO adsorbent by arranging a CO adsorbent downstream of the DPF under the same experimental conditions. In addition, the exhaust gas temperature at the time of the said experiment is about 100 degreeC. As shown in FIG. 4 (b), if a CO adsorbent is used, it is possible to suppress the discharge of CO generated during oxidation of PM to the outside.

(Desorption control of CO adsorbent)
After performing the regeneration control, desorption control of the CO adsorbent 24 is performed when a predetermined desorption condition is satisfied. In the desorption control, CO adsorbed on the CO adsorbent 24 is desorbed by exhaust heat, and this CO is purified by the oxidation catalyst 14. Here, an example of desorption conditions is when the temperature of the oxidation catalyst 14 is equal to or higher than the activation temperature of the catalyst and the temperature of the exhaust gas is equal to or higher than the desorption temperature of the CO adsorbent 24. In this case, the temperature of the exhaust gas may be obtained from the operating state of the internal combustion engine instead of the temperature sensor or the like. The “oxidation catalyst activation temperature” is a temperature at which the purification activity for CO appears. Thereby, CO desorbed from the CO adsorbent 24 can be reliably purified by the activated oxidation catalyst 14.

  The ECU 40 performs desorption control when the desorption condition is satisfied. For example, the ECU 40 performs desorption control when a certain time has elapsed when it is determined that the CO in the CO adsorbent 24 has been sufficiently desorbed. finish. FIG. 5 is an operation explanatory diagram showing a state in which the desorption control of the CO adsorbent is performed in the first embodiment of the present invention. As shown in FIG. 5, in the desorption control, the exhaust gas is circulated through the bypass passage 22 by switching the bypass switching valve 26 to the bypass position. As a result, exhaust gas having a temperature higher than the desorption temperature passes through the CO adsorbent 24, so that CO is desorbed from the CO adsorbent 24. The desorbed CO flows into the activated oxidation catalyst 14 and is purified by this catalyst.

  Here, the relationship between the activation temperature of the catalyst and the desorption temperature of the adsorbent will be described. FIG. 6 is an explanatory diagram comparing the desorption temperature of the CO adsorbent and the activation temperature of the oxidation catalyst in the first embodiment of the present invention. As shown in this figure, in the present embodiment, the desorption temperature of the CO adsorbent 24 (temperature at which CO is desorbed) is higher than the activation temperature of the oxidation catalyst 14 (temperature at which CO purification activity appears). It is configured as follows. Thereby, when the temperature of the exhaust gas becomes equal to or higher than the desorption temperature, the CO purification activity of the oxidation catalyst 14 has already appeared, so that desorption control can be started smoothly. Further, as the desorption condition, for example, it is only necessary to determine whether or not the temperature of the exhaust gas is equal to or higher than the desorption temperature, so that the control can be simplified.

[Specific Processing for Realizing Embodiment 1]
FIG. 7 is a flowchart of control executed by the ECU in the first embodiment of the present invention. Note that the routine shown in FIG. 7 is repeatedly executed during operation of the internal combustion engine.

  In the routine of FIG. 7, it is first determined whether or not the above-described regeneration condition is satisfied (step 100). When this determination is satisfied, regeneration control of the DPF 16 is executed (step 102). In this case, the regeneration control is terminated when, for example, a certain time elapses when it is determined that the PM in the DPF 16 is sufficiently oxidized. When the regeneration condition is not satisfied, it is determined whether or not the above-described desorption condition is satisfied (step 104), and when the determination is satisfied, desorption control of the CO adsorbent 24 is executed (step 106). In this case, the desorption control is terminated when, for example, a certain time elapses when it is determined that the CO in the CO adsorbent 24 is sufficiently desorbed. On the other hand, when the determination in step 104 is not satisfied, since both the regeneration condition and the desorption condition are not satisfied, normal exhaust control is performed (step 108).

  Thus, according to the present embodiment, when the regeneration control of the DPF 16 is performed, the flow direction of the gas flowing in the exhaust passage 12 can be switched to the reverse direction by the exhaust cutoff valve 28 and the backflow release valve 30. In this state, ozone can be supplied to the DPF 16 by the ozone generator 18 and the PM collected in the DPF can be oxidized by ozone. The gas generated by this oxidation reaction can be caused to flow into the CO adsorbent 24 via the oxidation catalyst 14, and CO in the gas can be adsorbed by the CO adsorbent 24.

  Thereby, even if the oxidation catalyst 14 is not activated at a low temperature or the like, it is possible to reliably prevent CO generated when the PM is oxidized from being discharged to the outside. Therefore, even when the internal combustion engine is stopped or cold started, the regeneration control of the DPF 16 can be freely performed while suppressing CO emission, and the exhaust emission at a low temperature can be improved. Moreover, in the present embodiment, by using the CO adsorbent 24, a gas collection system such as CO can be realized with a simple structure.

  Further, after the internal combustion engine is warmed up, the desorption control of the CO adsorbent 24 can be performed using the heat of the exhaust gas. In this desorption control, the exhaust gas is caused to flow through the bypass passage 22 by the bypass switching valve 26, and the exhaust gas flows in the forward direction from the upstream side to the downstream side by the exhaust cutoff valve 28 and the backflow release valve 30. Can be set. As a result, CO can be separated from the CO adsorbent 24 by the exhaust heat, and this CO can be joined to the exhaust passage 12 and purified by the oxidation catalyst 14.

  As described above, in this embodiment, it is possible to easily perform regeneration control of the DPF 16 and desorption control of the CO adsorbent 24 only by switching the gas flow direction. In addition, even if the DPF 16 having a relatively large heat capacity is not disposed on the upstream side of the oxidation catalyst 14, the above-described effects can be obtained. As a result, when the internal combustion engine is started, the oxidation catalyst 14 can be quickly activated by the exhaust heat, and the exhaust emission can be further improved. In particular, in the present embodiment, the CO adsorbent 24 is disposed in the bypass passage 22. For this reason, in normal exhaust control, since the exhaust gas does not pass through the CO adsorbent 24, the exhaust heat can be efficiently transmitted to the oxidation catalyst 14, and the activation of the oxidation catalyst 14 can be accelerated. it can.

  Further, according to the present embodiment, the ECU 40 determines that the amount of PM that needs to be processed is collected in the DPF 16 by comparing the pressure difference detected by the pressure sensor 34 with the reference determination value. can do. When this determination is established and the temperature environment is such that ozone is not thermally decomposed, regeneration control of the DPF 16 can be executed, and the DPF 16 can be efficiently regenerated at an appropriate timing.

  Further, according to the present embodiment, regeneration control of the DPF 16 can be executed even when the internal combustion engine is stopped or in a low output operation state such as an idle operation. In such a state, since the temperature of the exhaust gas is often lower than the thermal decomposition temperature of ozone, regeneration control can be performed efficiently. Further, for example, in a hybrid vehicle using both an internal combustion engine and an electric motor, the internal combustion engine may be stopped when traveling by the electric motor. Therefore, the regeneration process of the DPF 16 can be smoothly performed using this stop period.

  Further, according to the present embodiment, since the exhaust cutoff valve 28 and the backflow release valve 30 are used as the direction switching means, the exhaust passage 12 is closed by the exhaust cutoff valve 28 in the regeneration control, and is generated in the DPF 16. Gas or the like can be circulated in the reverse direction toward the CO adsorbent 24. At this time, the backflow release valve 30 can open a portion where the gas flows out from the CO adsorbent 24 to the atmosphere, and can smoothly introduce new gas into the CO adsorbent 24.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 2]
FIG. 8 is an overall configuration diagram for explaining a system configuration according to the second embodiment of the present invention. The system according to the present embodiment includes an oxidation catalyst 14, a DPF 16, an ozone generator 18, a CO adsorbent 50, an exhaust cutoff valve 28, and the like, almost as in the first embodiment. However, in this embodiment, the bypass passage 22, the bypass switching valve 26, the backflow release valve 30, etc. are eliminated, and a CO adsorbent 50 as a gas collecting means is provided in the exhaust passage 12 upstream of the oxidation catalyst 14. In this respect, the configuration is different from that of the first embodiment.

  Further, in the present embodiment, regeneration control of the DPF 16 is performed when the same regeneration conditions as in Embodiment 1 are satisfied. In the regeneration control, the exhaust cutoff valve 28 is closed and the ozone generator 18 is operated. As a result, when ozone is supplied into the exhaust passage 12 from the ozone supply port 20, this ozone flows in the reverse direction through the exhaust passage 12 and flows into the DPF 16 to oxidize PM, as in the first embodiment. Let The gas flowing out of the DPF 16 passes through the oxidation catalyst 14 and flows into the CO adsorbent 50. At this time, CO in the gas is adsorbed by the CO adsorbent 50.

  On the other hand, when the regeneration condition is not satisfied, normal exhaust control is executed as in the first embodiment. In this case, exhaust gas having a temperature higher than the desorption temperature flows into the CO adsorbent 50 after the internal combustion engine is warmed up. As a result, the CO adsorbed in the CO adsorbent 50 is desorbed from the adsorbent, flows into the oxidation catalyst 14, and is oxidized by the catalyst 14. That is, in the present embodiment, the desorption control of the CO adsorbent 50 is performed in the normal exhaust control. Therefore, the flowchart embodying the control of the present embodiment is obtained by excluding steps 104 and 106 from the flowchart of the first embodiment (FIG. 7).

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. And especially in this Embodiment, the bypass channel | path 22, the bypass switching valve 26, the backflow release valve 30, etc. can be abbreviate | omitted, and a system structure can be simplified.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 3]
FIG. 9 is an overall configuration diagram for explaining a system configuration according to the third embodiment of the present invention. The system of the present embodiment includes a gas collecting device 60 as a gas collecting means and a shutoff valve 68 as a passage closing means in addition to the oxidation catalyst 14, the DPF 16, and the ozone generator 18 similar to those in the first embodiment. , 70, and the configuration differs from that of the first embodiment in this respect.

  The gas collection device 60 is a device for collecting the gas flowing out from the DPF 16 and supplying the gas to the oxidation catalyst 14, and includes a gas storage unit 62 and an actuator 64. Here, the gas storage portion 62 is formed as a sealed space having a sufficient volume, and is connected to the exhaust passage 12 on the upstream side of the oxidation catalyst 14 by a ventilation passage 66.

  The actuator 64 allows gas to flow into and out of the gas storage portion 62. For example, a piston mechanism that expands and contracts the volume in the gas storage portion 62, or pressurizes and increases the pressure in the gas storage portion 62. It is composed of a variable pressure mechanism for reducing the pressure. The actuator 64 sucks the gas flowing through the exhaust passage 12 into the gas storage portion 62 in accordance with a control signal input from the ECU 40 and the gas in the gas storage portion 62 from the vent passage 66 to the exhaust passage. One of the discharge operations to discharge to 12 is executed.

  In the present embodiment, the ozone generator 18 (ozone supply port 20) is connected to the gas storage unit 62 of the gas collection device 60. That is, the ozone generator 18 is connected to the exhaust passage 12 via the gas storage portion 62 and the air passage 66. For this reason, the ozone generated by the ozone generator 18 is once stored in the gas storage unit 62 and then supplied to the DPF 16 through the exhaust passage 12 and the like.

  On the other hand, the shutoff valves 68 and 70 are configured by electromagnetically driven on / off valves or the like controlled by the ECU 40. The upstream cutoff valve 68 is provided in the exhaust passage 12 on the upstream side of the gas collection device 60. Further, the downstream shutoff valve 70 is provided in the exhaust passage 12 on the downstream side of the DPF 16. Therefore, as shown in FIG. 10 to be described later, when both shut-off valves 68 and 70 are closed, a part of the exhaust passage 12 becomes a closed passage 72 closed on both sides, and this closed passage 72 is formed from the outside. It is in a blocked state. In this state, the DPF 16, the ozone generator 18, and the gas storage unit 62 are connected to the closed passage 72. Further, the exhaust passage 12 (blocking passage 72) is provided with a temperature sensor 74 that detects the temperature of the exhaust gas on the downstream side of the DPF 16.

Next, the control of the present embodiment will be described with reference to FIGS. 10 and 11.
(DPF regeneration control)
FIG. 10 is an operation explanatory diagram showing gas collection control executed during regeneration of the DPF. First, during operation of the internal combustion engine, the ozone generator 18 is operated prior to DPF regeneration control, and ozone is stored in the gas storage unit 62 in advance. When the internal combustion engine is stopped, DPF regeneration control is executed.

  In the regeneration control, first, the shutoff valves 68 and 70 are closed, and the closed passage 72 is formed in the middle of the exhaust passage 12. Then, by operating the gas collection device 60, the ozone stored in the gas storage unit 62 is released. As a result, the ozone released from the gas storage unit 62 into the closed passage 72 flows into the DPF 16 and oxidizes PM. At this time, if the temperature of the exhaust gas is relatively low, CO is generated by the oxidation reaction of PM, and this CO flows out from the DPF 16 into the closed passage 72. In addition, excess ozone that does not contribute to the oxidation reaction also stays in the closed passage 72.

  Therefore, as shown in FIG. 10, the ECU 40 performs gas collection control for collecting CO and ozone in the closed passage 72 by the gas collection device 60. In the gas collection control, a suction operation is executed by the gas collection device 60 with the shutoff valves 68 and 70 closed, and CO and ozone staying in the closed passage 72 are sucked into the gas storage unit 62. And it waits until an internal combustion engine is restarted in this state.

(Collecting gas purification control)
FIG. 11 is an operation explanatory diagram showing collected gas purification control. When the internal combustion engine is restarted in a state where CO and ozone are collected by the gas collection device 60, collected gas purification control is executed. In the collected gas purification control, when the temperature of the exhaust gas detected by the temperature sensor 74 becomes equal to or higher than the activation temperature of the oxidation catalyst 14, a discharge operation is performed by the gas collection device 60. At this time, since the shut-off valves 68 and 70 are open, CO and ozone released from the gas storage portion 62 flow into the oxidation catalyst 14 along with the flow of the exhaust gas. Thereby, CO generated during the regeneration of the DPF can be reduced and purified, and ozone can be decomposed.

[Specific Processing for Realizing Embodiment 3]
FIG. 12 is a flowchart of control executed by the ECU in the third embodiment of the present invention. In the routine shown in FIG. 12, first, the shutoff valves 68 and 70 are held open during normal travel (step 200). In this state, the output of the temperature sensor 74 is 250 ° C. or higher. When the internal combustion engine is in operation, the process stands by while performing the process of step 200. During engine operation, ozone is stored in the gas storage unit 62 by the ozone generator 18 (step 202).

  Next, when it is detected in step 204 that the internal combustion engine has stopped, it is determined whether or not the temperature of the exhaust gas is 250 ° C. or higher (step 206). When this determination is satisfied, the DPF regeneration control is not performed, and the process ends as it is or waits until the determination is not satisfied (step 208). This is because when the ambient temperature is 250 ° C. or higher, the thermal decomposition rate of ozone increases and the oxidation efficiency of PM decreases. The specific value of the temperature of 250 ° C. is only an example adopted in the present embodiment, and the present invention is not limited to this.

  On the other hand, when the determination at step 206 is not established, regeneration control and gas collection control of the DPF 16 are executed. That is, first, the shutoff valves 68 and 70 are closed (step 210), and the ozone stored in the gas storage unit 62 is released into the closed passage 72 (step 212). Then, CO and ozone generated by the oxidation of PM are collected by the gas collecting device 60 (step 214), and then the shutoff valves 68 and 70 are opened (step 216).

  Next, when it is detected in step 218 that the internal combustion engine has started, it is determined whether or not the temperature of the exhaust gas is 200 ° C. or higher (step 220). When this determination is not satisfied, the process is terminated without performing the collected gas purification control or waits until the determination is satisfied (step 222). Here, 200 ° C. is the exhaust temperature corresponding to the activation temperature of the oxidation catalyst 14. If the exhaust temperature is 200 ° C. or higher, it can be determined that the oxidation catalyst 14 is activated. In addition, the specific value of the temperature of 200 ° C. is only an example adopted in the present embodiment, and the present invention is not limited to this.

  When the determination in step 220 is established, the CO and ozone collected in the gas storage unit 62 are returned to the exhaust passage 12 (step 224). Thereby, CO and ozone are purified by the activated oxidation catalyst 14 (step 226).

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as in the first embodiment. And especially in this Embodiment, since it was set as the structure which uses the gas collection apparatus 60, when performing the reproduction | regeneration processing of DPF16, collected CO and excess ozone should be collected by the gas collection apparatus 60. Can do. For this reason, even if the oxidation catalyst 14 is not activated due to a low temperature or the like, it is possible to reliably prevent CO and ozone generated during PM oxidation from being discharged to the outside. When the oxidation catalyst 14 is activated, the collected CO and ozone can be supplied to the oxidation catalyst 14. As a result, the oxidation catalyst 14 can stably purify CO and active oxygen, and can improve exhaust emission.

  In addition, since the gas collection device 60 includes the gas storage unit 62 and the actuator 64, when the regeneration process of the DPF 16 is performed, the suction operation is performed by the actuator 64, so that CO or ozone is removed from the gas storage unit 62. It can be easily collected. Further, when the purification process of the collected gas is performed, a release operation is performed by the actuator 64, whereby CO and ozone in the gas storage unit 62 are released from the gas storage unit 62, and these gases are directed toward the oxidation catalyst 14. It can be supplied smoothly.

  Moreover, in the present embodiment, the shutoff valves 68 and 70 are provided in the exhaust passage 12 as passage closing means. Thereby, the shutoff valves 68 and 70 can close the exhaust passage 12 to form the closed passage 72 when the regeneration process of the DPF 16 is performed. Thereby, the ozone supplied to the blocking passage 72 by the ozone generator 18 can be efficiently introduced into the DPF 16 by utilizing the sealing property of the blocking passage 72. Further, CO and excess ozone that have flowed out of the DPF 16 can be efficiently collected by the gas collecting device 60 by utilizing the sealing property of the blocking passage 72.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Features of Embodiment 4]
FIG. 13 is an overall configuration diagram for explaining a system configuration according to the fourth embodiment of the present invention. As in the third embodiment, the system of the present embodiment includes an oxidation catalyst 14, a DPF 16, an ozone generator 18, a gas collection device 80 as a gas collection means, and a shut-off valve as a passage closing means. 92 and 94, and the gas collection device 80 includes a gas storage portion 82 and an actuator 84.

  However, the gas storage portion 82 is provided on the downstream side of the DPF 16, the collection passage 86 for collecting gas from the exhaust passage 12 into the gas storage portion 82, and the gas collected in the gas storage portion 82 upstream of the oxidation catalyst 14. And a discharge passage 88 for discharging to the exhaust passage 12 on the side. The discharge passage 88 is provided with a discharge control valve 90 that is controlled by the ECU 40.

  The upstream shut-off valve 92 is provided in the exhaust passage 12 between the oxidation catalyst 14 and the DPF 16, and the downstream shut-off valve 94 is provided in the exhaust passage 12 on the downstream side of the DPF 16 and the collection passage 86. . The ozone generator 18 is provided at a position downstream of the upstream shut-off valve 92 and upstream of the DPF 16, and is configured to supply ozone from the upstream side to the DPF 16.

  That is, the DPF 16, the ozone generator 18, and the gas storage portion 82 (collection passage 86) are connected to the closing passage 96 formed when the shutoff valves 92 and 94 are closed. Further, a temperature sensor 98 for detecting the temperature of the exhaust gas is provided on the downstream side of the oxidation catalyst 14. And the exhaust gas purification apparatus of this Embodiment can perform gas collection control and collection gas purification control substantially the same as Embodiment 3. FIG. Hereinafter, these controls will be described.

(DPF regeneration control)
In the regeneration control, when the internal combustion engine is stopped, the shutoff valves 92 and 94 and the release control valve 90 are first closed, and a closed passage 96 is formed in the middle of the exhaust passage 12. Then, ozone is supplied to the closed passage 96 by the ozone generator 18, and PM accumulated in the DPF 16 is oxidized by ozone. At this time, the gas collection device 80 performs a suction operation. As a result, CO that has flowed out of the DPF 16 and excess ozone remaining in the closed passage 96 are collected in the gas storage portion 82 via the collection passage 86 that is always kept open. When this collection operation is completed, the shut-off valves 92 and 94 are opened, but the release control valve 90 is kept closed. And it waits until an internal combustion engine is restarted in this state.

(Collecting gas purification control)
The trapped gas purification control is executed when the internal combustion engine is restarted and the temperature of the exhaust gas becomes equal to or higher than the activation temperature of the oxidation catalyst 14 as in the case of the third embodiment. In this control, first, the release control valve 90 is opened, and the gas collection device 80 performs the release operation. As a result, the gas in the gas storage portion 82 is discharged to the exhaust passage 12 through the discharge passage 88. At this time, since the shut-off valves 92 and 94 are open, the released CO and ozone flow into the oxidation catalyst 14 along the flow of the exhaust gas, and are oxidized or decomposed.

[Specific processing for realizing Embodiment 4]
FIG. 14 is a flowchart of control executed by the ECU in the fourth embodiment of the present invention. In the routine shown in FIG. 14, first, the shut-off valves 92 and 94 and the release control valve 90 are held open during normal travel (step 300). In this state, the output of the temperature sensor 98 is 250 ° C. or higher. When the internal combustion engine is in operation, the process stands by while performing the process of step 300.

  Next, when it is detected in step 302 that the internal combustion engine has stopped, it is determined whether or not the temperature of the exhaust gas is 250 ° C. or higher (step 304). When this determination is satisfied, the process ends without performing DPF regeneration control for the reason described in the third embodiment, or waits until the determination is not satisfied (step 306).

  On the other hand, if the determination in step 304 is not established, regeneration control and gas collection control of the DPF 16 are executed. That is, first, the shutoff valves 92 and 94 and the release control valve 90 are closed (step 308), and ozone is supplied to the closed passage 96 (step 310). Then, CO and ozone in the closed passage 96 are collected by the gas collecting device 80 (step 312), and then only the shut-off valves 92 and 94 are opened (step 314).

  Next, when the start of the internal combustion engine is detected in step 316, it is determined whether or not the temperature of the exhaust gas is 200 ° C. or more (step 318). For the reasons described, the process ends without performing the collected gas purification control or waits until a determination is made (step 320). When the determination in step 318 is established, the shut-off valves 92 and 94 and the release control valve 90 are opened (step 322), and the CO and ozone collected in the gas storage unit 82 are returned to the exhaust passage 12 ( Step 324). As a result, CO and ozone can be purified by the activated oxidation catalyst 14 (step 326).

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the third embodiment. In the present embodiment, since the collection passage 86 and the discharge passage 88 are connected to the gas storage portion 82 of the gas collection device 80, the CO and ozone suction and discharge operations are different from each other. 86, 88 can be performed smoothly.

  In the first embodiment, steps 100 and 102 shown in FIG. 7 show a specific example of the reproduction control means. Steps 104 and 106 show specific examples of the desorption control means. In the third embodiment, steps 210 and 214 in FIG. 12 show a specific example of the collection control means, and steps 220 and 224 show a specific example of the supply control means. Furthermore, in Embodiment 4, steps 308 and 312 in FIG. 14 show a specific example of the collection control means, and steps 318, 322 and 324 show a specific example of the supply control means.

  In the second embodiment, the backflow release valve 30 is eliminated. However, the present invention is not limited to this. For example, a backflow release valve 30 may be provided in the exhaust passage 12 on the upstream side of the CO adsorbent 50 and the backflow release valve 30 may be opened during regeneration control of the DPF 16.

  In the third and fourth embodiments, the gas collection devices 60 and 80 are used as the gas collection means. However, the present invention is not limited to this, and the third and fourth embodiments may be configured to use a CO adsorbent instead of the gas collection devices 60 and 80. Similarly, in the present invention, in the first and second embodiments, a gas collecting device may be used instead of the CO adsorbents 24 and 50.

In the embodiment, ozone has been described as an example of the active oxygen added to the exhaust gas. However, the present invention is not limited to this, and instead of ozone, other types of active oxygen (for example, oxygen negative ions represented by O ⁻ , O ²⁻ , O ₂ ⁻ , O ₃ ⁻ , O _n ^−, etc.) are used. ) May be added to the exhaust gas.

  In the embodiment, the ozone generator 18 is provided outside the exhaust gas flow path and is arranged separately from the DPF 16. However, the present invention is not limited to this, and the ozone generator may be arranged in the exhaust gas flow path or in the DPF 16. When such an arrangement is adopted, for example, plasma may be generated by high-voltage discharge or the like in the exhaust gas flow path or inside the DPF, thereby generating active oxygen (such as ozone). .

  Furthermore, in the embodiment, the case where the present invention is applied to the internal combustion engine 10 including a diesel engine has been described as an example. However, the present invention is not limited to this, and is widely applied to various internal combustion engines including, for example, a gasoline engine. To get.

10 Internal combustion engine 12 Exhaust passage 14 Oxidation catalyst 16 DPF (PM filter)
18 Ozone generator (active oxygen supply means)
20 Ozone supply port 22 Bypass passage 24, 50 CO adsorbent (gas collecting means)
26 Bypass switching valve (Bypass switching means)
28 Exhaust shut-off valve (direction switching means)
30 Backflow release valve (direction switching means)
32, 74, 98 Temperature sensor (temperature acquisition means)
34 Pressure sensor (pressure detection means)
40 ECU
60, 80 Gas collection device (gas collection means)
62, 82 Gas storage part 64, 84 Actuator 66 Ventilation path 68, 70, 92, 94 Shut-off valve (passage closing means)
72, 96 Closure passage 86 Collection passage 88 Release passage 90 Release control valve

Claims (14)

An oxidation catalyst that is provided in an exhaust passage through which exhaust gas of the internal combustion engine flows and purifies unpurified components in the exhaust gas by oxidation;
A PM filter that is provided in the exhaust passage downstream of the oxidation catalyst and collects particulate matter in the exhaust gas;
Active oxygen supply means for supplying active oxygen to the PM filter;
A CO adsorbent disposed or connected to the exhaust passage upstream of the oxidation catalyst and adsorbing carbon monoxide in the gas;
Direction switching for switching the gas flow direction so that the gas in the exhaust passage flows in the reverse direction from the PM filter toward the CO adsorbent when the active oxygen is supplied to the PM filter by the active oxygen supply means. Means,
A regeneration control means for driving the active oxygen supply means and the direction switching means to circulate active oxygen in the reverse direction when performing a regeneration process for oxidizing the PM in the PM filter;
An exhaust emission control device for an internal combustion engine, comprising: A passage that bypasses a part of the exhaust passage on the upstream side of the oxidation catalyst, and a bypass passage in which the CO adsorbent is disposed;
Bypass switching means for switching a flow path of the exhaust gas between a part of the exhaust passage and the bypass passage;
Desorption control means for causing exhaust gas to flow through the bypass passage by the bypass switching means when performing desorption processing for desorbing carbon monoxide from the CO adsorbent;
The exhaust emission control device for an internal combustion engine according to claim 1, comprising: Pressure detecting means for detecting a pressure difference between the upstream side and the downstream side of the PM filter;
The exhaust purification device for an internal combustion engine according to claim 1 or 2, wherein the regeneration control means is configured to determine whether or not to perform regeneration processing of the PM filter according to the temperature of the exhaust gas and the pressure difference. .   The regeneration control means is configured to execute regeneration processing of the PM filter when the temperature of the exhaust gas is lower than the thermal decomposition temperature of the active oxygen and the pressure difference is larger than a predetermined reference determination value. The exhaust emission control device for an internal combustion engine according to claim 3.   The internal combustion engine according to any one of claims 1 to 4, wherein the regeneration control unit is configured to execute regeneration processing of the PM filter when the internal combustion engine is in a stopped state or a low output operation state. Exhaust purification equipment. A temperature acquisition means for acquiring the temperature of the oxidation catalyst;
3. The exhaust gas purification of an internal combustion engine according to claim 2, wherein the desorption control unit is configured to execute the desorption processing of the CO adsorbent when at least the temperature of the oxidation catalyst is equal to or higher than the activation temperature of the catalyst. apparatus.   The internal combustion engine according to any one of claims 1 to 6, wherein a desorption temperature at which carbon monoxide is desorbed from the CO adsorbent is set to be higher than an activation temperature at which the oxidation catalyst is activated. Exhaust purification equipment. The direction switching means includes an exhaust cutoff valve that opens and closes the exhaust passage on the downstream side of the PM filter,
8. The regeneration control unit is configured to supply active oxygen to the PM filter by the active oxygen supply unit in a state where the exhaust cutoff valve is closed when performing regeneration processing of the PM filter. The exhaust gas purification apparatus for an internal combustion engine according to any one of the above. The direction switching means includes a backflow release valve that opens and shuts off a portion of the CO adsorbent from which the gas flowing in the reverse direction flows out.
The exhaust purification device of an internal combustion engine according to claim 8, wherein the regeneration control means is configured to open the reverse flow release valve when performing regeneration processing of the PM filter.   The exhaust purification device for an internal combustion engine according to any one of claims 1 to 9, wherein the active oxygen supply means is configured to supply ozone as the active oxygen. An oxidation catalyst that is provided in an exhaust passage through which exhaust gas of the internal combustion engine flows and purifies unpurified components in the exhaust gas by oxidation;
A PM filter that is provided in the exhaust passage downstream of the oxidation catalyst and collects particulate matter in the exhaust gas;
Active oxygen supply means for supplying active oxygen to the PM filter;
Gas collecting means capable of collecting the gas flowing out of the PM filter and supplying the gas to the oxidation catalyst;
When the active oxygen is supplied to the PM filter, the collection control means for collecting the gas flowing out from the PM filter in the gas collection means,
Supply control means for supplying the gas collected by the gas collecting means to the oxidation catalyst when the temperature of the exhaust gas rises above a predetermined value;
An exhaust emission control device for an internal combustion engine, comprising:   The exhaust gas purification apparatus for an internal combustion engine according to claim 11, wherein the collection means is a CO adsorbent that adsorbs carbon monoxide flowing out of the PM filter. The gas collecting means includes
A gas storage unit connected to the exhaust passage;
An actuator for causing the gas to flow into and out of the gas storage unit;
An exhaust emission control device for an internal combustion engine according to claim 11 or 12, comprising: A passage closing means capable of forming a closed passage blocked from outside by closing a part of the exhaust passage;
The exhaust emission control device for an internal combustion engine according to any one of claims 11 to 13, wherein at least the PM filter, the active oxygen supply means, and the gas collection means are connected to the closed passage.

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