JP2006204975A - NOx PURIFIER - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an NOx purifier spraying a fuel into exhaust gas with the fuel consumption reduced. <P>SOLUTION: The purifier has a catalyst body 1, an oxidation catalyst section 11, an NOx purifying section 12 and a fuel spraying means 2. In the catalyst body 1, a wall part 107 dividing the oxidation catalyst section 11 divides a part of the exhaust gas flow passage 101 in the upstream of the oxidation catalyst section 11, and the wall part 107 is made of a heat-conductive material. The purifier can reduce a fuel sprayed into exhaust gas by heating the exhaust gas flowing into the oxidation catalyst section with the heat generated in the oxidation catalyst section and operate with low fuel consumption. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a NOx purification device, and more particularly to a NOx purification device with improved fuel efficiency.

  Exhaust gas discharged from an internal combustion engine such as an automobile contains components such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx), and particulate matter (PM). These components not only have an impact on the environment, but also have a risk of harming human health, and their reduction has been studied.

  As a method for reducing these harmful components, a lean burn system that reduces the amount of emission of these components from the internal combustion engine by diluting the fuel, and a catalyst such as a precious metal for these components in the exhaust gas. There is a method of decomposing and purifying to innocuous components using. Here, the lean burn system is a method for reducing the generation amount of harmful components. Normally, even in the lean burn system, harmful components are decomposed and purified using a catalyst.

  There are two types of automobile engines: gasoline engines that use gasoline as fuel and diesel engines that use light oil as fuel. In particular, it is known that a diesel engine discharges a larger amount of PM than a gasoline engine. Normally, PM is captured by a filter catalyst such as DPF and removed from the exhaust gas.

  The lean burn system is a method for reducing harmful components emitted from an internal combustion engine by increasing the ratio of air and fuel (air-fuel ratio, A / F) from the stoichiometric air-fuel ratio and reducing the fuel injection amount. The lean burn system reduces the burden on the environment by reducing harmful components emitted from the internal combustion engine. And this lean burn system has been adopted not only in gasoline engines but also in diesel engines.

  In general, a vehicle is equipped with a catalyst device using a noble metal such as an oxidation catalyst, a reduction catalyst, or a three-way catalyst, and these components are decomposed and purified by this catalyst device. The decomposition and purification of CO and HC proceeds by an oxidation reaction, and the decomposition and purification of NOx proceeds by a reduction reaction.

  In particular, in a diesel engine, harmful components are removed with a catalytic metal after PM is removed with a filter catalyst, and the exhaust gas temperature may be lower than the activation temperature of the catalytic metal when purified with the catalytic metal. When the exhaust gas temperature becomes low, harmful components are not purified by the catalyst metal.

  Therefore, a NOx purification device that decomposes and purifies NOx in the exhaust gas has been developed. As this NOx purification device, for example, a fuel injection means for injecting engine fuel into exhaust gas containing NOx, an oxidation catalyst portion having Pt (catalyst metal) disposed downstream thereof, and a downstream thereof. And an NOx purification catalyst. This NOx purification device injects fuel into exhaust gas, oxidizes and decomposes this fuel at an oxidation catalyst portion disposed downstream, and exerts catalytic activity on the exhaust gas and NOx purification catalyst by heat generation when the decomposition reaction proceeds. The temperature is raised above the temperature to decompose and purify NOx.

  However, such a NOx purification device has a problem that fuel consumption is increased because it is necessary to continuously inject the fuel into the exhaust gas during operation of the engine.

  This invention is made | formed in view of the said actual condition, and makes it a subject to provide the NOx purification apparatus by which the amount of fuel consumption was reduced in the NOx purification apparatus which injects a fuel in waste gas.

  In order to solve the above problems, the present inventor has studied the NOx purifying device, and as a result, the purifying device that heats the exhaust gas flowing into the oxidation catalyst unit with the heat generated in the oxidation catalyst unit can solve the above problem. I found it.

  That is, the NOx purification device of the present invention comprises a catalyst main body in which an exhaust gas flow path through which exhaust gas flows by a wall section, an oxidation catalyst section having an oxidation catalyst supported on the surface of the wall section defining the exhaust gas flow path, A NOx purification unit having a NOx purification catalyst supported on the surface of the wall section defining the exhaust gas flow path and downstream of the oxidation catalyst unit, and fuel injection for injecting fuel into the exhaust gas provided upstream of the oxidation catalyst unit And a catalyst body, wherein a part of the wall part defining the oxidation catalyst part defines a part of the exhaust gas flow channel upstream of the oxidation catalyst part, and a part of the wall part Is made of a material capable of transferring heat.

  In the NOx purification device of the present invention, the wall portion that divides the oxidation catalyst portion defines a part of the flow path of the exhaust gas that flows into the oxidation catalyst portion. That is, the heat generated in the oxidation catalyst part is transmitted to the exhaust gas through this wall part. And since the exhaust gas which flows into an oxidation catalyst part by a wall part is heated, the calorie | heat amount provided to exhaust gas in an oxidation catalyst part decreases. That is, it is possible to reduce the amount of fuel injected into the exhaust gas because heat is generated in the oxidation catalyst section. As a result, the NOx purification device can be operated with low fuel consumption.

  The NOx purification device of the present invention includes a catalyst main body in which an exhaust gas flow path through which exhaust gas flows by a wall section, an oxidation catalyst section having an oxidation catalyst supported on the surface of the wall section defining the exhaust gas flow path, and an exhaust gas flow A NOx purification part having a NOx purification catalyst carried on the surface of the wall part defining the passage and downstream of the oxidation catalyst part; and fuel injection means for injecting fuel into the exhaust gas provided upstream of the oxidation catalyst part; Have.

  The NOx purification device of the present invention injects fuel into the exhaust gas in the fuel injection means, and oxidatively decomposes the injected fuel in the oxidation catalyst section. When the fuel is oxidized and decomposed, heat is generated and the exhaust gas temperature rises. Then, the heated exhaust gas raises the temperature of the NOx purification unit to the catalyst activation temperature or higher. Thereby, the NOx purification unit can decompose and purify NOx in the exhaust gas.

  In the NOx purification device according to the present invention, the catalyst main body has a part of the wall that partitions the oxidation catalyst part, a part of the exhaust gas flow channel upstream of the oxidation catalyst part, and a part of the wall part is heated. It is made of a material that can be transmitted. That is, in the NOx purification device of the present invention, a part of the wall section that defines the portion of the exhaust gas flow path where the oxidation catalyst section is formed forms a part of the wall section that defines the upstream portion of the oxidation catalyst section. A part of the wall portion is made of a material capable of transferring heat. That is, the upstream portion and the oxidation catalyst portion are disposed adjacent to each other with (a part of) the wall portion. The heat generated in the oxidation catalyst part is transmitted to the exhaust gas flowing in the upstream exhaust gas passage through the wall part that partitions the oxidation catalyst part. Thereby, the temperature of the exhaust gas flowing into the oxidation catalyst part increases. The amount of heat required for heating at the oxidation catalyst portion (applied to the exhaust gas) is reduced. This indicates that the amount of fuel injected into the exhaust gas upstream of the oxidation catalyst unit can be reduced. That is, it shows that the NOx purification device of the present invention can be operated with low fuel consumption.

  In the NOx purification device of the present invention, a wall portion that divides an exhaust gas flow channel and that divides a portion where an oxidation catalyst portion is formed is a wall portion that divides a portion upstream of the oxidation catalyst portion of the exhaust gas flow channel I am doing. That is, one wall section divides the oxidation catalyst portion of the exhaust gas flow channel and the upstream portion of the oxidation catalyst portion of the exhaust gas flow channel. The heat of the oxidation catalyst part is transmitted through this wall part to heat the exhaust gas passing through the upstream part of the exhaust gas flow path. When one wall section separates the oxidation catalyst section of the exhaust gas flow path and the upstream portion of the oxidation catalyst section of the exhaust gas flow path, the exhaust gas flow path is disposed adjacent to one another through the wall section It can be. At this time, the exhaust gas flow may be in the same direction or in different directions in the adjacent exhaust gas passages separated by one wall portion. It is preferable that the exhaust gas flow path is partitioned so that the exhaust gas flows in the opposite direction. In other words, it is preferable that the exhaust gas flow path be partitioned upstream of the oxidation catalyst portion.

  It is preferable that the distance between the upstream portion for heating the exhaust gas and the oxidation catalyst portion is short. When the distance becomes long, the exhaust gas heated in the upstream portion and heated to a high temperature releases heat while flowing through the exhaust gas flow path, so that the exhaust gas with insufficient heating flows into the oxidation catalyst portion. When the exhaust gas flow path is folded upstream of the oxidation catalyst part, the folded part where the exhaust gas flow path is folded is preferably located immediately upstream of the oxidation catalyst part.

  In the NOx purification device of the present invention, the catalyst body preferably has an exhaust gas flow path in a state where the direction in which the exhaust gas flows and the direction in which the exhaust gas is discharged are the same direction. That is, an opening through which the exhaust gas flows into the opposite surfaces of the catalyst body and an opening through which the exhaust gas is discharged are formed. This structure indicates that the catalyst body can be installed in a direction along the exhaust gas flow, and that the mountability is improved. In order to adopt this configuration, it is preferable that the exhaust gas flow path of the catalyst body is folded downstream of the oxidation catalyst portion.

  In the NOx purification device of the present invention, the fuel injection means injects fuel into the exhaust gas into the oxidation catalyst portion, and the oxidation catalyst portion decomposes this fuel. That is, the fuel injection means may be provided at any position as long as it is upstream of the oxidation catalyst section. That is, the fuel injection means may be provided either in the exhaust gas flow passage partitioned by the catalyst body or upstream of the catalyst body. The fuel injection means preferably injects fuel into the heated exhaust gas. That is, it is preferable that the fuel injection means injects the fuel immediately upstream of the oxidation catalyst portion.

  In the NOx purification device of the present invention, the oxidation catalyst unit and the NOx purification unit are not particularly limited as long as they are composed of devices or members capable of exhibiting the above functions, and may be the same as conventionally known devices. it can.

  The fuel injection means may be any means capable of injecting fuel into exhaust gas containing NOx discharged from the internal combustion engine. That is, the method for injecting fuel into the exhaust gas is not limited.

  The fuel injected into the exhaust gas in the fuel injection means is not particularly limited as long as it is a fuel that generates heat when it is decomposed by the oxidation catalyst carried on the oxidation catalyst section. An example of such a fuel is a lower hydrocarbon compound. The fuel injected by the injection means is preferably the fuel of the internal combustion engine because it does not require a new tank for storing fuel or can be replenished simultaneously with the fuel of the internal combustion engine.

  The oxidation catalyst oxidizes and decomposes the fuel injected into the exhaust gas. The oxidation reaction of the fuel that proceeds by the oxidation catalyst is an exothermic reaction, and the exhaust gas is heated by this heat. For example, a decomposition reaction of a fuel made of hydrocarbon is shown in Chemical Formula 1.

  In the NOx purification device of the present invention, the oxidation catalyst is not particularly limited as long as it is an oxidation catalyst capable of generating heat by oxidative decomposition of the fuel. An example of such an oxidation catalyst is Pt. The method for supporting the oxidation catalyst on the oxidation catalyst portion is not particularly limited. Even if the catalyst metal is directly supported on the surface of the wall, a porous support layer made of a heat-resistant inorganic oxide such as alumina is formed on the surface of the wall, and the catalyst metal is supported on the porous support layer. Good.

  The NOx purification unit is disposed downstream of the oxidation catalyst unit. That is, the exhaust gas heated in the oxidation catalyst unit flows into the NOx purification unit. The NOx purification part is heated to the catalyst activation temperature or higher by the heated exhaust gas, and the NOx in the exhaust gas can be purified. Further, the fuel that has not been decomposed in the oxidation catalyst unit also flows into the exhaust gas flowing into the NOx purification unit. When the fuel is a hydrocarbon, the fuel that has not been decomposed (not completely oxidized) serves as a reaction source for the reduction reaction for NOx purification. That is, the reaction shown in Chemical Formula 2 proceeds.

  The NOx purification unit is not particularly limited as long as it is a device that can purify NOx. For example, a porous support of a heat-resistant inorganic oxide can be formed on the surface of a wall section that defines the exhaust gas flow path, and a catalyst metal such as a noble metal can be supported on the surface of the support. Examples of the catalyst metal that purifies NOx include Ag, Cu, and Mn.

  In the NOx purification device of the present invention, the structure of the catalyst body that divides the exhaust gas flow path is not particularly limited as long as it is integrated in a state where heat generated in the oxidation catalyst portion can be transferred to the upstream portion. Absent. For example, it is preferably made of a heat exchangeable material such as a heat resistant metal such as ceramics or stainless steel.

  The NOx purification device of the present invention is effective in purifying exhaust gas from an internal combustion engine that discharges NOx, and the type of the internal combustion engine is not limited. More preferably, the internal combustion engine is a diesel engine and the fuel is light oil.

The NOx purification device of the present invention includes a sensor for sensing exhaust gas flowing through each exhaust gas flow path, a calculation means for calculating fuel injected in the fuel injection means based on a detection signal from the sensor, and a calculation result from the calculation means And control means for controlling the fuel injection of the fuel injection means based on the above. That is, by controlling fuel injection based on the sensing result of the sensor, it is possible to prevent excessive fuel from being injected into the exhaust gas, and to suppress an increase in fuel consumption of the entire apparatus. That is, fuel consumption can be improved. Here, a sensor that measures the state of exhaust gas flowing into the NOx purification device, the temperature of exhaust gas discharged from the NOx purification device, and the content of constituent components can be used. In addition, the sensor may be directly attached to the heat exchanger, or an O ₂ sensor or the like that is attached in advance to the vehicle may be used.

  Hereinafter, the present invention will be described using examples.

Example 1
The NOx purification device of this embodiment is a NOx purification device that purifies NOx of exhaust gas from a diesel engine. The NOx purification device of the present embodiment has the configuration shown in FIGS. FIG. 1 is a diagram showing the configuration of each device of the exhaust system of a diesel engine in which the NOx purification device is assembled, and FIG. 2 is a diagram schematically showing the configuration of the catalyst body of the NOx purification device.

  The catalyst body 1 has an inlet 100 through which exhaust gas flows into the upper surface, an exhaust port 106 through which exhaust gas is discharged at the lower surface, and an exhaust gas passage 10 through which exhaust gas flows. A plurality of exhaust gas passages 10 are defined in the catalyst body 1. The plurality of exhaust gas flow paths 10 are partitioned so as to be substantially N-shaped. Specifically, the exhaust gas flow channel 10 includes a flow channel 101 extending downward from the inflow port 100, a flow channel 103 extending upward in which a lower end of the flow channel 101 is connected via a folded portion 102, and a flow channel 103. And a flow path 105 that extends downward and is connected to the upper end via a turn-back portion 104 and opens a discharge port 106 on the lower surface.

  The catalyst carrier 1 is formed in a substantially prismatic shape from stainless steel. As described above, the channel 101 and the channel 103 are separated by the partition wall 107, and the channel 103 and the channel channel 105 are separated by the partition wall 108.

  An oxidation catalyst portion 11 made of an oxidation catalyst layer in which Pt is supported on a porous support layer formed by coating and baking alumina slurry is formed on a wall surface defining the flow path 103 and on the lower wall surface. Further, the upper wall surface defining the flow path 103 is formed with a NOx purification section 12 composed of a NOx purification catalyst layer in which Ag is supported on a porous support layer coated with alumina slurry and fired. Yes. The oxidation catalyst unit 11 and the NOx purification unit 12 are each formed to be half the length of the flow path 103.

  The injection nozzle 2 injects fuel into exhaust gas flowing in a pipe line connecting the diesel engine and the catalyst body 1. The injection nozzle 2 injects fuel immediately upstream of the catalyst body 1.

  The NOx purification device of this embodiment is installed in the exhaust system of a diesel engine as shown in FIG. In the exhaust system of the diesel engine in which the NOx purification device of this embodiment is assembled, the diesel engine 3, the oxidation catalyst 4, and the NOx purification device are arranged in this order. The injection nozzle 2 is connected to the fuel tank 5 of the diesel engine 3 and injects fuel (light oil) stored in the fuel tank 5 into the exhaust gas.

  Below, operation | movement of the NOx purification apparatus of a present Example is demonstrated based on operation | movement when the exhaust gas of the diesel engine 3 is purified.

  As the diesel engine 3 and the oxidation catalyst 4, a conventionally known diesel engine and oxidation catalyst are used.

  The exhaust system of the diesel engine 3 is assembled with a temperature sensor 60, a NOx sensor 61, and a calculation means. The calculation means determines the state of the exhaust gas based on the signals from the plurality of sensors 60 and 61. The plurality of sensors 60 and 61 and the calculation means may use members that are conventionally assembled in a vehicle. The calculation means is also connected to the injection nozzle 21 of the NOx purification device, and can control the fuel injection from the injection nozzle 2.

  When the diesel engine 3 to which the NOx purification device is assembled is operated, exhaust gas containing CO, HC, NOx and PM is generated. The exhaust gas discharged from the diesel engine 3 first flows into the oxidation catalyst 4 where the oxidation catalyst 4 decomposes and purifies CO and HC. Thereby, CO and HC in the exhaust gas are removed.

  Then, fuel is injected from the injection nozzle 2 into the exhaust gas in which CO and HC are decomposed in the oxidation catalyst 4. As a result, the fuel is mixed into the exhaust gas.

  The exhaust gas mixed with the fuel flows into the inside of the catalyst body 1 from the inlet 100, flows through the flow path 101, and reaches the folded portion 102. The folded portion 102 connects the flow channel 101 and the flow channel 103 with the exhaust gas flow channel 10 folded back, and the exhaust gas that has reached the folded portion 102 flows into the flow channel 103 and flows through the flow channel 103.

  An oxidation catalyst unit 11 is formed below (upstream side) of the flow path 103. When exhaust gas flows through the oxidation catalyst unit 11, the fuel in the exhaust gas is oxidized and decomposed by Pt supported on the oxidation catalyst unit 11. The The oxidative decomposition reaction of the fuel is an exothermic reaction, and the exhaust gas temperature rises due to the generated heat, and the temperature of the wall portions (the partition walls 107 and 108 and the wall portions connecting both the partition walls) that partition the flow path 103 increases.

  The heated exhaust gas flows through the flow path 103 and reaches the NOx purification unit 12 of the flow path 103 to heat Ag to an activation temperature or higher. At this time, the wall part which divides the flow path 103 in the oxidation catalyst part 11 is also heated, and the heat of this wall part is transmitted to the NOx purification part to heat Ag. That is, the NOx purification unit 12 is heated to a temperature equal to or higher than the catalyst activation temperature by the heat of the oxidation catalyst unit 11, and decomposes and purifies NOx in the exhaust gas that has reached the NOx purification unit 12.

  Thereafter, the flow direction of the exhaust gas is turned back at the turn-back portion 104 and flows into the flow path 105 and is discharged from the discharge port 106.

  In the above-described exhaust gas flow, the heat generated in the oxidation catalyst portion 11 of the catalyst body 1 heats the partition wall 107 in the wall portion defining the flow path 103. The partition wall 107 partitions a part of the flow path 101, and the heat transferred to the partition wall 107 is also transmitted to the exhaust gas flowing through the flow path 101. That is, the exhaust gas from which NOx is purified in the catalyst main body 1 is also heated in the flow path 101, so that the amount of heat imparted in the oxidation catalyst unit 11 (for raising the temperature of the NOx catalyst unit to the activation temperature of Ag or higher). The amount of heat) can be reduced. This indicates that the amount of fuel injected by the injection nozzle 2 into the exhaust gas can be reduced, and that the fuel consumption required for NOx purification can be reduced. The fuel injected from the injection nozzle 2 is a fuel used for the operation of the diesel engine 3. As a result, the fuel efficiency of the diesel engine 3 provided with the NOx purification device of the present embodiment was improved.

  Furthermore, since the catalyst body 1 is made of stainless steel, the partition walls that separate the flow path 105 and the flow path 101 are also made of stainless steel. That is, the heat of the high-temperature exhaust gas flowing through the flow path 105 is transmitted to the adjacent flow path 101 through the partition wall, and the exhaust gas flowing through the flow path 101 can be heated.

  Further, in the exhaust system of the diesel engine 3 of the present embodiment, the sensing results of the plurality of sensors 60 and 61 are transmitted to the calculation means, and the state of the exhaust gas is determined. That is, when the calculation means determines that exhaust gas having a high temperature is flowing into the NOx purification unit 12, the amount of fuel injected from the injection nozzle 2 is reduced, and the amount of heat generated by the fuel is reduced. Furthermore, when it is determined that the exhaust gas flowing into the NOx purification unit 12 is sufficiently heated, control can be performed so that fuel is not injected from the injection nozzle 2. That is, the fuel injection amount can be greatly reduced as compared with the conventional NOx purification device. As a result, the amount of fuel used in the diesel engine 3 for NOx purification can be reduced, and the overall fuel consumption including the diesel engine 3 can be improved.

(Example 2)
The present embodiment is a NOx purification device having the same configuration as that of the first embodiment except that the configuration of the catalyst body 1 is different. A cross-sectional view of the catalyst body 1 of this example is shown in FIG.

  The catalyst body 1 of the present embodiment is the same as the catalyst body 1 of the embodiment 1 except that the folded portion 104 is composed of a number of punching holes opened in the partition wall 108 and the heat insulating material 13 is disposed on the outer peripheral surface thereof. It has a configuration.

  The NOx purification device of this embodiment can purify NOx in the exhaust gas in the same manner as the NOx purification device of Embodiment 1, and exhibits the same effect.

  Further, in the NOx purification device of this embodiment, since the heat insulating material 13 is disposed on the outer periphery of the catalyst body 1, the temperature of the catalyst body 1 is less likely to decrease due to cooling. In other words, since the catalyst body 1 itself can maintain a high temperature, the amount of fuel injected into the exhaust gas at the injection nozzle 2 can be reduced.

(Example 3)
The present embodiment is a NOx purification device having the same configuration as that of the first embodiment except that the configuration of the catalyst body 1 is different. A cross-sectional view of the catalyst body 1 of this example is shown in FIG.

  The catalyst body 1 of this example is the same as that of Example 2, except that the oxidation catalyst part 11 is also formed on the surface of the folded part 102 and the NOx purification part 12 is also formed on the surface of the flow path 105. It has the same configuration as

  The NOx purification device of this embodiment can purify NOx in the exhaust gas in the same manner as the NOx purification device of Embodiment 1, and exhibits the same effect.

  Further, in the NOx purification device of this embodiment, the area where the oxidation catalyst unit 11 and the NOx purification unit 12 are formed is increased, so that the purification performance of HC, CO, and NOx is improved.

Example 4
The present embodiment is a NOx purification device in which a catalyst body and an injection nozzle are integrated. The NOx purification device of this example is shown in FIG.

  The NOx purification device of the present embodiment has a configuration in which the injection nozzle 2 injects fuel into the folded portion 102 of the catalyst body 1 of the first embodiment. Specifically, the injection nozzle 2 is provided in the vicinity of the lower end portion of the side surface of the catalyst body 1 so that fuel can be simultaneously injected into the folded portions 102 of the plurality of exhaust gas flow paths.

  In the NOx purification device of the present embodiment, the fuel can be mixed with the exhaust gas heated in the flow path 101 by the injection nozzle 2 directly injecting the fuel into the folded portion 102. Then, the fuel is immediately decomposed at the oxidation catalyst unit 11.

  The NOx purification device of this embodiment can purify NOx in the exhaust gas in the same manner as the NOx purification device of Embodiment 1, and exhibits the same effect.

  Further, in the NOx purification device of this embodiment, since the injection nozzle 2 is formed integrally with the catalyst body 1, it is not necessary to install the injection nozzle in the exhaust system, and the NOx purification device can be easily assembled. it can.

(Example 5)
The present embodiment is a NOx purification device having the same configuration as that of the fourth embodiment except that the outer peripheral shape is a substantially cylindrical shape. The NOx purification device of this example is shown in FIG.

  The NOx purification device of this embodiment can purify NOx in the exhaust gas in the same manner as the NOx purification device of Embodiment 4, and exhibits the same effect.

  Further, the NOx purification device of the present embodiment has an approximately cylindrical shape in the outer periphery, and has an effect that it can be easily attached to the exhaust pipe.

It is the figure which showed the structure of the exhaust system of the diesel engine by which the NOx purification apparatus of Example 1 was assembled | attached. 2 is a cross-sectional view of a catalyst body of the NOx purification device of Example 1. FIG. 6 is a cross-sectional view of a catalyst body of a NOx purification device of Example 2. FIG. 6 is a cross-sectional view of a catalyst body of a NOx purification device of Example 3. FIG. FIG. 6 is a view showing a NOx purification device of Example 4. FIG. 6 is a view showing a NOx purification device of Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Catalyst main body 10: Exhaust gas flow path 100: Inlet 101, 103, 105: Flow path 102, 104: Folding part 106: Exhaust port 107, 108: Partition 109: Punching hole 11: Oxidation catalyst part 12: NOx purification part 13: Thermal insulation material 2: Injection nozzle 3: Diesel engine 4: Oxidation catalyst 5: Fuel tank 60: Temperature sensor 61: NOx sensor

Claims (4)

A catalyst body in which an exhaust gas flow path through which exhaust gas flows is partitioned by a wall;
An oxidation catalyst portion having an oxidation catalyst supported on the surface of the wall portion defining the exhaust gas flow path;
A NOx purification section having a NOx purification catalyst carried on the surface of the wall section defining the exhaust gas flow path and downstream of the oxidation catalyst section;
Fuel injection means for injecting fuel into the exhaust gas provided upstream of the oxidation catalyst section;
NOx purification device having
The catalyst main body is a material in which a part of the wall partitioning the oxidation catalyst part defines a part of the exhaust gas flow channel upstream of the oxidation catalyst part, and the part of the wall part is capable of transferring heat. A NOx purification device comprising:   2. The NOx purification device according to claim 1, wherein the exhaust gas flow path of the catalyst body is turned immediately upstream of the oxidation catalyst portion.   The NOx purification device according to claim 1, wherein the fuel injection unit injects the fuel immediately upstream of the oxidation catalyst unit.   2. The NOx purification device according to claim 1, wherein the catalyst body has the exhaust gas flow path in a state where a direction in which the exhaust gas flows and a direction in which the exhaust gas is discharged are the same.

Images