JP2008175136A - Exhaust emission control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device efficiently purifying an HC component emitted from an engine in clod start. <P>SOLUTION: The exhaust emission control system 1 having a filter member 6 which traps HC component in exhaust gas G and is interposed in an exhaust gas channel 5 of an engine 2, is provided with an ozone forming device 10 supplying ozone to the filter member from a right upstream side of the filter member in an exhaust gas flow direction. The filter member has a layer containing heat resistant particles formed on a surface of an exhaust gas passage through which exhaust gas passes in the filter member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device in which a filter member for trapping HC components in exhaust gas is interposed in an exhaust path of an engine.

  For example, in a vehicle such as an automobile, the exhaust gas discharged from the engine contains air pollutants such as HC (hydrocarbon), CO (carbon monoxide), and NOx (nitrogen oxide). Is provided with an exhaust gas purification device having a catalyst for purifying exhaust gas. In such an exhaust gas purification device, HC and CO are oxidized and purified, and NOx is reduced and purified.

  In the exhaust gas purification device, for example, at the time of cold start such as when the engine is started, the temperature of the exhaust gas is low, the catalyst in the exhaust gas purification device is not activated, and the HC in the exhaust gas is sufficiently purified. It is a problem not to be. On the other hand, as a means for improving the purification performance of HC in the exhaust gas at the time of cold start, a catalyst containing a zeolite-based HC trap material for trapping HC is known in the catalyst in the exhaust gas purification device. Yes.

  In an exhaust gas purification apparatus having a catalyst containing a zeolite-based HC trap material, unburned HC components contained in a large amount of exhaust gas at the time of cold start are trapped in the pores of zeolite, which is a porous material, When the temperature rises, the trapped HC component is released and is oxidized and purified by the active catalyst.

  However, if the exhaust gas purification device is disposed in the exhaust path directly under the engine where exhaust gas is discharged, specifically, directly under the exhaust manifold, in order to exert the catalyst purification performance at an early stage, the zeolite-based HC trap material It is known that the exhaust gas flowing in the exhaust path directly under the exhaust manifold becomes extremely hot depending on the engine load and the number of revolutions of the catalyst, so that the crystal structure of zeolite collapses and there is a problem with long-term durability. It has been.

Further, as an example of improving the purification performance of HC in exhaust gas at the time of cold start without using a zeolite-based HC trap material, for example, Patent Document 1 discloses an exhaust pipe located upstream of a catalytic purification device. There is disclosed an exhaust gas treatment device that injects ozone into the inside and converts at least a part of hydrocarbons in the exhaust gas into carbon monoxide inside an exhaust pipe located upstream of the catalytic purification device.
JP-A-2005-207316

  However, as disclosed in Patent Document 1, even when ozone is injected into the exhaust pipe to convert a part of HC in the exhaust gas into carbon monoxide in the exhaust path, In the case where the temperature of the disposed catalytic purification device itself is not raised, the catalyst does not exhibit sufficient purification performance, and not only converted carbon monoxide but also HC not converted to carbon monoxide There is a fear that is not purified by.

  Further, at the time of cold start, HC in the exhaust gas exists not only as a gas but also as a mist. This mist-like HC wets the catalyst layer of the exhaust gas purification device, for example, the catalyst layer containing the catalyst metal or the heat-resistant oxide supported on the honeycomb carrier disposed in the exhaust path of the engine. The HC purification performance of the layer may be reduced.

  Therefore, the present invention has been made in view of the above technical problem, and is capable of efficiently purifying the gaseous and mist-like HC components in the exhaust gas discharged from the engine during cold start. An object is to provide a purification device.

  For this reason, the exhaust gas purifying apparatus according to claim 1 of the present application is an exhaust gas purifying apparatus in which a filter member for trapping HC in the exhaust gas is interposed in the exhaust path of the engine. Active oxygen supply means for supplying active oxygen to the filter member from directly upstream of the filter member in the direction is provided.

  The invention according to claim 2 of the present application is the invention according to claim 1, wherein the filter member includes a layer containing heat-resistant particles on an exhaust gas passage surface through which exhaust gas passes through the filter member. It is characterized by that.

  Furthermore, the invention according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the exhaust path branches on the upstream side of the exhaust path in the flow direction of the exhaust gas and is connected on the downstream side of the exhaust path. A main path and a bypass path are provided, and the filter member is interposed in the bypass path.

  Still further, the invention according to claim 4 of the present application is the invention according to claim 3, wherein the temperature detection means for detecting the temperature of the exhaust gas, and the exhaust gas in the exhaust path in the main path or the bypass path. Switching means for switching the main path and the bypass path so as to flow, control means for controlling the operation of the switching means, and the exhaust path downstream of the junction where the main path and the bypass path are connected The control means further includes a three-way catalyst, and the control means causes the exhaust gas to flow through the bypass path when the temperature of the exhaust gas detected by the temperature detection means is lower than a predetermined temperature. Thus, when the temperature of the exhaust gas is equal to or higher than a predetermined temperature, the operation of the switching means is controlled so that the exhaust gas flows through the main path. Is obtained by it said.

  Furthermore, the invention according to claim 5 of the present application is characterized in that, in the invention according to claim 1 or 2, a three-way catalyst is disposed in the exhaust path downstream of the filter member. is there.

  Still further, the invention according to claim 6 of the present application is the invention according to claim 4 or 5, wherein a NOx trap material for trapping NOx is disposed in the exhaust path downstream of the three-way catalyst, or The three-way catalyst contains a NOx trap material for trapping NOx.

  According to the exhaust gas purifying apparatus according to claim 1 of the present application, HC trapped in the filter member can be oxidized and purified by active oxygen, and HC in the exhaust gas can be efficiently purified. At the time of cold start, the HC component in the exhaust gas discharged from the engine is in the form of gas and mist, but the gaseous HC component collides with the mist HC component trapped by the filter member and is absorbed. The gaseous and mist-like HC components in the exhaust gas can be efficiently purified.

  According to the invention of claim 2 of the present application, the filter member includes a layer containing heat-resistant particles on the exhaust gas passage surface through which the exhaust gas passes through the filter member. The trap rate of the HC component can be improved, and the effect can be more effectively achieved.

  Furthermore, according to the invention according to claim 3 of the present application, the exhaust path includes a main path and a bypass path that are branched on the upstream side of the exhaust path and connected on the downstream side of the exhaust path, and the filter member is provided in the bypass path. By being interposed, it is possible to cause the exhaust gas to flow through the bypass path provided with the filter member only at the time of cold start.

  Furthermore, according to the invention of claim 4 of the present application, at the time of cold start, the exhaust gas can be passed through the filter member to efficiently purify the gaseous and mist-like HC components in the exhaust gas and The catalyst can ensure the purification performance of CO and NOx in the exhaust gas, and can reduce the back pressure resistance of the exhaust gas without passing the exhaust gas through the filter member during normal travel. Exhaust gas purification performance can be ensured.

  Furthermore, according to the invention of claim 5 of the present application, the three-way catalyst is disposed in the exhaust path downstream of the filter member, so that the purification performance of HC in the exhaust gas can be further improved. In addition, the purification performance of CO and NOx in the exhaust gas can be ensured.

  Furthermore, according to the invention of claim 6 of the present application, when active oxygen is supplied to the filter member, ozone and air become excessive, the exhaust gas becomes a lean atmosphere, and the exhaust gas contains a large amount of NOx. However, since this NOx can be trapped by the NOx trap material, the release of NOx into the atmosphere can be suppressed. The NOx trapped in the NOx trap material in the lean atmosphere is released in the rich atmosphere and is reduced and purified.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory diagram conceptually showing the structure of the exhaust gas purifying apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the exhaust gas purification device 1 is provided in an exhaust path 5 for releasing an exhaust gas G discharged from an engine 2 such as a gasoline engine into the atmosphere. In order to bring the catalyst into an active state at an early stage, it is preferably provided in the exhaust path 5 directly below the engine 2, specifically directly below the exhaust manifold 3.

  The exhaust gas purification apparatus 1 includes a filter member 6 that traps HC contained in the exhaust gas G, a three-way catalyst 7 for purifying HC, CO, and NOx contained in the exhaust gas G, NOx trap material 8 that traps NOx contained in the exhaust gas G. The filter member 6, the three-way catalyst 7, and the NOx trap material 8 are sequentially provided in the exhaust path 5 in the flow direction of the exhaust gas G.

  As shown in FIG. 3 to be described later, the filter member 6 includes a base material 22 made of a ceramic such as SiC, and a coating layer 23 in which the base material 22 is coated with heat-resistant particles such as alumina. The mist-like and gaseous unburned HC components contained in the exhaust gas G are trapped. As the filter member 6, for example, a member having the same structure as a diesel particulate filter (DPF) for collecting PM (particulate) discharged from a diesel engine is used.

  The three-way catalyst 7 is disposed in the exhaust path 5 downstream of the filter member 6 in the flow direction of the exhaust gas G, and a catalyst layer containing a catalyst metal, alumina, or the like is carried on, for example, a honeycomb-shaped catalyst carrier. ing. The three-way catalyst 7 oxidizes and purifies HC and CO in the exhaust gas G, and reduces and purifies NOx.

  The NOx trap material 8 is disposed in the exhaust passage 5 downstream of the three-way catalyst 7 in the flow direction of the exhaust gas G. When the exhaust gas G is in a lean atmosphere, the NOx trap material 8 occludes the exhaust gas G. When the atmosphere is rich, the stored NOx component is released and reduced and purified by the HC component that is contained in a rich atmosphere. As the NOx trap material, for example, alkali metal or alkaline earth metal can be used.

  Further, the exhaust gas purification device 1 includes an ozone generator 10 as active oxygen supply means for supplying active oxygen to the filter member 6 on the upstream side of the filter member 6 in the flow direction of the exhaust gas G. A predetermined amount of air is supplied to the ozone generator 10 from an air supply source (not shown) via an air pump 11.

  The ozone generator 10 is configured to generate ozone from the air supplied from the air supply source, and the ozone generated by the ozone generator 10 is upstream of the filter member 6 through the ozone supply path 12. To the filter member 6.

  Further, the exhaust gas purification apparatus 1 includes a temperature sensor (not shown) that detects the temperature of the exhaust gas G, and for example, a thermocouple is used as the temperature sensor. In addition, the exhaust gas purification device 1 is provided with a control unit 15 that controls a configuration related to the exhaust gas purification device 1. The control unit 15 performs various controls such as operation control of the air pump 11 and operation control of the ozone generator 10 based on various information such as the temperature of the exhaust gas detected by the temperature sensor. The control unit 15 includes a microcomputer as a main part.

  FIG. 2 is a cross-sectional explanatory view schematically showing a cross section of a filter member used in the exhaust gas purification device. As described above, the exhaust path 5 is provided with the filter member 6 for trapping HC in the exhaust gas G. The filter member 6 is on the exhaust gas inflow side where the exhaust gas G flows from the exhaust path 5. And an exhaust gas outflow side passage 16b adjacent to the exhaust gas inflow side passage 16a through which the exhaust gas G flows out to the exhaust gas passage 5.

  The passage 16a on the exhaust gas inflow side is formed such that the upstream end face in the flow direction of the exhaust gas G is opened without being blocked by the plug 17, and the end face on the downstream side in the flow direction of the exhaust gas G is formed by the plug 18. It is sealed. On the other hand, in the exhaust gas outflow side passage 16b, the end face on the upstream side in the flow direction of the exhaust gas G is plugged by the plug 17, and the end face on the downstream side in the flow direction of the exhaust gas G is not blocked by the plug 18. An opening is formed.

  In the filter member 6, the exhaust gas inflow side passage 16 a and the exhaust gas outflow side passage 16 b that are elongated in the flow direction of the exhaust gas G are partitioned by the partition walls 20 and are alternately arranged. The outer periphery of the filter member 6 is covered with a case 19, and the filter member 6 is held and fixed to the exhaust path 5 via the case 19.

  FIG. 3 is an enlarged cross-sectional view of a part A of FIG. 2 showing a main part of the filter member. As shown in this figure, in the filter member 6, a plurality of pores 21 are provided in the partition wall portion 20 that divides the passage 16 a on the exhaust gas inflow side and the passage 16 b on the exhaust gas outflow side, and the exhaust gas passes through the pores 21. When the exhaust gas G flows from the inflow side passage 16a to the exhaust gas outflow side passage 16b adjacent to the exhaust gas inflow side passage 16a, unburned HC components in the exhaust gas G are trapped in the partition wall portion 20. It is like that.

As described above, the filter member 6 is formed on, for example, alumina (α-alumina, β-alumina, other alumina), SiC, Si on the base material 22 made of ceramic such as Si ₃ N ₄ , SiC, and cordierite. _A coating layer 23 made of heat-resistant particles such as ₃ N ₄ , titania, metal-containing silicate, SiO ₂ , Ce-based oxide, Zr-based oxide, and Fe-based oxide is formed. The coating layer 23 includes a partition wall portion 20 that partitions an exhaust gas passage surface through which the exhaust gas G passes through the filter member 6, that is, an exhaust gas inflow side passage 16 a and an exhaust gas outflow side passage 16 b, and the partition wall portion 20. Is formed on the surface through which the exhaust gas G passes.

  As shown in FIG. 3, in the filter member 6, the mist-like HC component 25 contained in the exhaust gas G collides with the coating layer 23 and is trapped at the cold start, and the gaseous HC component is further trapped in the coating layer 23. By being taken into the filter member 6 by the mist-like HC component trapped in the mist, the mist-like and gaseous HC component in the exhaust gas G can be trapped.

  Further, since the coating layer 23 is formed of heat-resistant particles such as alumina, the surface area for trapping the mist-like HC component 25 can be increased, and the trap amount of the HC component in the exhaust gas G can be increased. Can do. Since HC trapped in the filter member 6 is oxidized and purified by ozone supplied by the ozone supply device 10, it is possible to prevent the coating layer 23 from containing a catalyst metal. The coating layer 23 is formed with a thickness of, for example, 2 μm to 10 μm. For example, the alumina having an average particle diameter of 0.1 μm to 1.0 μm can be used as the heat resistant particles.

  In the present embodiment, the filter member 6 has a plurality of exhaust gas inflow passages 16a and exhaust gas outflow passages 16b in the flow direction of the exhaust gas G, and the passages 16a and 16b in the flow direction of the exhaust gas G. Although a ceramic filter member having end faces alternately sealed is used, other filter members such as a metal filter member such as stainless steel can also be used.

  FIG. 4 is a perspective view showing another filter member used in the exhaust gas purification device. As shown in this figure, in the exhaust gas purifying apparatus 1, a metal flat plate W1 such as a stainless steel plate and a corrugated plate W2 obtained by processing a metal flat plate such as a stainless steel plate into a corrugated shape are overlapped. A filter member 36 formed by winding the combined flat plate W1 and corrugated plate W2 in a spiral shape may be used.

  In the filter member 36, a plurality of passages 37 are formed by the flat plate W1 and the corrugated plate W2, and the corrugated plate W2 has a plurality of pores (not shown) so that the exhaust gas flows between the adjacent passages 37. Is provided. In the filter member 36, HC in the exhaust gas G is trapped when the exhaust gas G flows between the adjacent passages 37 through the pores. Moreover, as the filter member 6, it is also possible to use a filter member made of ceramic or metal having a three-dimensional network structure.

  In the exhaust gas purifying apparatus 1 having the above configuration, for example, at the time of cold start such as when the engine is started, mist and gaseous HC components contained in the exhaust gas G are trapped by the filter member 6, and this filter member 6 The HC component trapped in is oxidized and purified by ozone supplied from the ozone generator 10.

  The control unit 15 supplies ozone to the filter member 6 during cold start based on the temperature of the exhaust gas detected by the temperature sensor, and oxidizes and purifies the HC component trapped in the filter member 6 Thus, the operation of the air pump 11 and the ozone generator 10 is controlled.

  Thus, according to the exhaust gas purification apparatus 1 according to the present embodiment, HC trapped in the filter member 6 can be oxidized and purified by active oxygen, and HC can be efficiently purified. At the cold start, the HC component in the exhaust gas G exhausted from the engine 2 is in the form of gas and mist, but the gaseous HC component collides with the mist HC component trapped by the filter member 6 and absorbs it. Therefore, the gaseous and mist HC components in the exhaust gas G can be purified efficiently.

  Further, the filter member 6 is provided with a layer 23 containing heat-resistant particles on the exhaust gas passage surface through which the exhaust gas G passes through the filter member 6, thereby improving the trap rate of HC components in the exhaust gas. And the effect can be more effectively achieved.

  Furthermore, since the three-way catalyst is disposed in the exhaust path downstream of the filter member, the purification performance of HC in the exhaust gas can be further improved, and the purification performance of CO and NOx in the exhaust gas can be improved. Can be secured.

  In the exhaust gas purification device 1, the NOx trap material 8 is disposed in the exhaust path 5 downstream of the three-way catalyst 7 in the flow direction of the exhaust gas G. You may make it contain the NOx trap material which traps a NOx component.

  For example, when active oxygen is supplied to the filter member 6 at the time of cold start such as when starting the engine, ozone and the remainder of the air supplied to generate ozone are added to the exhaust gas G. The exhaust gas G becomes a lean atmosphere, and the exhaust gas G contains a large amount of NOx. However, the NOx trap material 8 is disposed in the exhaust path 5 downstream of the three-way catalyst 6, or three Since the NOx trap material is contained in the original catalyst 6, NOx can be trapped by the NOx trap material, so that the release of NOx into the atmosphere can be suppressed. The NOx trapped in the NOx trap material in the lean atmosphere is released in the rich atmosphere and is reduced and purified.

  FIG. 5 is a schematic explanatory view conceptually showing the structure of the exhaust gas purifying apparatus according to the second embodiment of the present invention. In addition, in the exhaust gas purification apparatus 40 which concerns on 2nd Embodiment, it comprises the same structure as the exhaust gas purification apparatus 1 which concerns on 1st Embodiment, and attaches | subjects the same code | symbol about what has the same effect | action, The above description is omitted.

  In the exhaust gas purification device 40, as in the exhaust gas purification device 1, the filter member 46, the three-way catalyst 7, and the NOx absorbent 8 are interposed in the exhaust gas path 45 of the exhaust gas G discharged from the engine 2 through the exhaust manifold 3. However, the filter member 46 is provided in a bypass path 42 that branches from the upstream side of the exhaust path 45 and is connected to the downstream side of the exhaust path 45.

  As shown in FIG. 5, the exhaust path 45 includes a main path 41 and a bypass path 42 that are branched on the upstream side of the exhaust path 45 and connected on the downstream side of the exhaust path 45, and the main path 41 and the bypass path 42 are connected to each other. The branching portion 43 that is branched is provided with a switching valve 44 as switching means for switching the main path 41 and the bypass path 42 so that the exhaust gas G flows into the main path 41 or the bypass path 42.

  The switching valve 44 closes the bypass path 42 and closes the bypass path (the state indicated by the solid line) to flow the exhaust gas G to the main path 41, and bypass path to close the main path 41 and flow the exhaust gas G to the bypass path 42. It is configured to be able to switch between an open state (a state indicated by a broken line).

  Further, the bypass passage 42 is provided with an ozone generator 50 that supplies active oxygen to the filter member 46 immediately upstream of the filter member 46 in the flow direction of the exhaust gas G. The ozone generator 50 includes an air supply source. Ozone is generated from air supplied from an air pump (not shown) via an air pump 51, and this ozone can be supplied to the filter member 46 from the upstream side of the filter member 46.

  Further, the exhaust gas purifying device 40 is a first temperature sensor that detects the temperature of the exhaust gas G in the exhaust gas passage 45 upstream from the branch portion 43 where the main path 41 and the bypass path 42 branch in the flow direction of the exhaust gas G. 55 and a second temperature sensor 56 for detecting the temperature of the exhaust gas G in the exhaust gas passage 45 downstream from the junction 57 where the main path 41 and the bypass path 42 are connected in the flow direction of the exhaust gas G.

  Based on the temperature of the exhaust gas detected by the first temperature sensor 55 and the second temperature sensor 56, the operation of the switching valve 44 is controlled by the control unit 60. The control unit 60 controls the operation of the switching valve 44 and performs various controls such as the operation control of the air pump 51 and the operation control of the ozone generator 50.

  Further, the three-way catalyst 7 and the NOx absorbent 8 disposed in the exhaust passage 45 are arranged in the flow direction of the exhaust passage G in the exhaust passage 45 downstream of the junction 57 where the main passage 41 and the bypass passage 42 are connected. They are arranged sequentially. Instead of providing the NOx absorbent 8 in the exhaust passage 45 downstream of the three-way catalyst 7, the three-way catalyst 7 may contain the NOx absorbent 8.

Next, the operation of the exhaust gas purification apparatus 40 having the above configuration will be described.
FIG. 6 is a control flowchart of the exhaust gas purifying apparatus according to the second embodiment of the present invention. In the exhaust gas purification device 40, first, whether or not the temperature Ta of the exhaust gas G is lower than a predetermined temperature in the closed state where the switching valve 44 closes the bypass route 42 and flows the exhaust gas G to the main route 41. Is determined (step # 1). As the temperature Ta of the exhaust gas G, the temperature detected by the first temperature sensor 55 provided immediately downstream of the exhaust manifold 3 is used. As the predetermined temperature, the temperature of the exhaust gas flowing into the catalyst is gradually increased, and the light-off temperature of the catalyst, which is the gas temperature when the exhaust gas purification rate reaches 50%, can be used, for example 250 A temperature such as ° C is set.

  When the determination result in step # 1 is YES, that is, at the time of cold start where the temperature Ta of the exhaust gas G is lower than a predetermined temperature, the exhaust gas G flows through the bypass path 42 in which the filter member 46 is interposed. The switching valve 44 is switched to the bypass path open state (step # 2). Then, supply of ozone from the ozone supply device 50 is started (step # 3).

  When supplying ozone, the amount of ozone supplied from the ozone supply device 50 is adjusted according to the temperature Ta of the exhaust gas G (step # 4). Specifically, since the three-way catalyst becomes active as the temperature Ta of the exhaust gas G rises, the amount of ozone supplied to the filter member 46 is increased according to the rise in the temperature Ta of the exhaust gas G. Reduce.

  Next, in step # 5, it is determined whether the temperature Tb of the exhaust gas G is equal to or higher than a predetermined temperature, and it is determined whether the three-way catalyst 7 disposed in the exhaust path 45 is in an active state. The As the temperature Tb of the exhaust gas G, the temperature detected by the second temperature sensor 56 provided in the exhaust gas passage 45 downstream from the junction 57 where the main path 41 and the bypass path 42 are connected is used. Note that the light-off temperature of the catalyst can be used as the predetermined temperature, and a temperature such as 250 ° C. is set, for example.

  If the determination result in step # 5 is YES, that is, if the temperature Tb of the exhaust gas G is equal to or higher than a predetermined temperature at which the three-way catalyst 7 is activated, the switching valve 44 closes the bypass path 42 and exhaust gas. The bypass path is closed to allow G to flow through the main path 41 (step # 6), and the supply of ozone from the ozone supply device 50 is stopped (step # 7).

  On the other hand, when the determination result in step # 1 is NO, that is, when the temperature Ta of the exhaust gas G is equal to or higher than a predetermined temperature, the exhaust gas G flows through the bypass path 42 in which the filter member 46 is interposed. Instead, the exhaust gas G flows through the main path 41 and is purified by the three-way catalyst 7 provided in the exhaust path 46.

  As described above, according to the exhaust gas purifying device 40 according to the present embodiment, the exhaust path 45 includes the main path 41 and the bypass path 42 that branch on the upstream side of the exhaust path 45 and are connected on the downstream side of the exhaust path 45. Since the filter member 46 is provided in the bypass path 42, the exhaust gas can flow through the bypass path 42 provided with the filter member 46 only at the time of cold start.

  In the exhaust gas purification device 40, at the time of cold start, the exhaust gas G can be passed through the filter member 46 to efficiently purify the gaseous and mist-like HC components in the exhaust gas G. NOx component purification performance can be ensured, and during normal travel, the exhaust gas G can be reduced without passing through the filter member 46, and the back pressure resistance of the exhaust gas G can be lowered. Performance can be ensured. If the filter member 46 is provided in the exhaust passage 45, the back pressure resistance of the exhaust gas G increases and the engine output and the fuel consumption decrease, but the exhaust gas purification device 40 increases the back pressure resistance of the exhaust gas G. Without lowering, it is possible to suppress a decrease in engine output and fuel consumption.

  In the exhaust gas purification device 40, the first temperature sensor 55 detects the temperature of the exhaust gas immediately below the exhaust manifold in the exhaust gas flow direction, and the second temperature sensor 56 detects the three-way in the exhaust gas flow direction. The temperature of the exhaust gas immediately above the catalyst is detected, and the operation of the switching valve 44 is controlled based on these temperatures, but the switching is based only on the temperature detected by the first temperature sensor or the second temperature sensor. The operation of the valve 44 may be controlled. It is also possible to provide a temperature sensor for detecting the temperature of the exhaust gas in the three-way catalyst 7 and to control the operation of the switching valve based on the temperature detected by the temperature sensor.

  As described above, the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the gist of the present invention.

  The present invention is an exhaust gas purification device that can efficiently purify HC components discharged from an engine during a cold start, and can be suitably applied to an exhaust system of a vehicle such as an automobile, for example.

It is a schematic explanatory drawing which shows notionally the composition of the exhaust gas purification device concerning a 1st embodiment of the present invention. It is a section explanatory view showing typically the section of the filter member used for the exhaust gas purification device. It is an expanded sectional view of the A section of FIG. 2 which shows the principal part of the said filter member. It is a perspective view which shows another filter member used for the said exhaust gas purification apparatus. It is a schematic explanatory drawing which shows notionally the structure of the exhaust-gas purification apparatus which concerns on the 2nd Embodiment of this invention. 3 is a control flowchart of the exhaust gas purification device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 40 Exhaust gas purification apparatus 2, Engine 5, 45 Exhaust path 6, 36, 46 Filter member 7 Three-way catalyst 8 NOx trap material 10, 50 Ozone generator 15 60 Control unit 23 Coating layer 41 Main path 42 Bypass path 44 Switching valve 55, 56 Temperature sensor 57 Junction part G Exhaust gas

Claims (6)

  An exhaust gas purification device in which a filter member for trapping HC in exhaust gas is interposed in an exhaust path of an engine, wherein active oxygen is supplied to the filter member from the upstream side of the filter member in the exhaust gas flow direction. An exhaust gas purifying device comprising active oxygen supply means for supplying   The exhaust gas purification device according to claim 1, wherein the filter member includes a layer containing heat-resistant particles on an exhaust gas passage surface through which the exhaust gas passes through the filter member.   The exhaust path includes a main path and a bypass path that branch on the upstream side of the exhaust path in the flow direction of the exhaust gas and are connected on the downstream side of the exhaust path, and the filter member is interposed in the bypass path. The exhaust gas purifying device according to claim 1 or 2, wherein the exhaust gas purifying device according to claim 1 or 2 is provided. Temperature detecting means for detecting the temperature of the exhaust gas;
Switching means for switching the main path and the bypass path so that the exhaust gas flows in the main path or the bypass path in the exhaust path;
Control means for controlling the operation of the switching means;
A three-way catalyst disposed in the exhaust path downstream of the junction where the main path and the bypass path are connected;
Further comprising
The control means is configured such that when the temperature of the exhaust gas detected by the temperature detection means is less than a predetermined temperature, the temperature of the exhaust gas is equal to or higher than the predetermined temperature so that the exhaust gas flows through the bypass path. And controlling the operation of the switching means so that the exhaust gas flows through the main path,
The exhaust gas purifying apparatus according to claim 3.   The exhaust gas purification device according to claim 1 or 2, wherein a three-way catalyst is disposed in the exhaust path downstream of the filter member.   The NOx trap material for trapping NOx is disposed in the exhaust path downstream from the three-way catalyst, or the NOx trap material for trapping NOx is contained in the three-way catalyst. Item 6. The exhaust gas purifying device according to Item 4 or 5.

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