WO2012157066A1

WO2012157066A1 - Exhaust purifying apparatus for internal combustion engine

Info

Publication number: WO2012157066A1
Application number: PCT/JP2011/061192
Authority: WO
Inventors: 伊藤　和浩; 中山　茂樹
Original assignee: トヨタ自動車株式会社
Priority date: 2011-05-16
Filing date: 2011-05-16
Publication date: 2012-11-22

Abstract

In order to supply a reducing agent appropriately in an exhaust purifying apparatus for an internal combustion engine, which exhaust purifying apparatus is provided with a catalyst disposed in an exhaust channel of the internal combustion engine and a supply apparatus for supplying the reducing agent to the catalyst, the supply apparatus supplies the reducing agent toward a location with a larger mass of exhaust rather than a location with a smaller mass of exhaust. Thus, an appropriate amount of the reducing agent in view of the mass of exhaust can be supplied.

Description

Exhaust gas purification device for internal combustion engine

The present invention relates to an exhaust purification device for an internal combustion engine.

An exhaust emission control device that purifies NOx by supplying urea water (NH ₃ ) in an amount corresponding to the estimated NOx generation amount to a selective reduction type NOx catalyst is known (see, for example, Patent Document 1). .

In such a conventional exhaust purification device, the attachment position of the injection valve, the injection hole shape, and the like are determined so that urea water (NH ₃ ) is uniformly distributed in the exhaust pipe. However, the NOx distribution in the exhaust gas may not be uniform due to the influence of the shape of the exhaust pipe. That is, the NOx distribution and the reducing agent distribution in the exhaust gas may deviate. For this reason, there is a possibility that the reducing agent is insufficient at locations where the NOx concentration in the exhaust is high, and the reducing agent becomes excessive at locations where the NOx concentration is low. As a result, the NOx purification rate may decrease, or NH ₃ remaining in the catalyst without being used for NOx purification may be biased and adsorbed to the catalyst. Furthermore, there is a possibility that NH ₃ may slip through the catalyst.

Further, a technique for measuring five parameters of exhaust flow rate, exhaust temperature, mixture temperature, mixture pressure, and atmospheric humidity, weighting each parameter, and supplying a reducing agent based on the weighted five parameters (For example, refer to Patent Document 2). In this technique, weighting of five parameters is learned so that the NOx distribution and the reducing agent distribution are matched. In order to make the NOx distribution and the reducing agent distribution coincide with each other, a plurality of reducing agent injection valves are provided. The supply amount of the reducing agent from each injection valve is controlled according to the NOx distribution.

However, when applied to a passenger car, the position where the injection valve is attached is limited. For this reason, it may be difficult to provide a plurality of injection valves. Further, since a plurality of injection valves must be controlled, there is a possibility that the control becomes complicated.

JP 2005-264731 A JP 2002-276344 A

The present invention has been made in view of the above-described problems, and an object thereof is to appropriately supply a reducing agent.

In order to achieve the above object, an exhaust gas purification apparatus for an internal combustion engine according to the present invention comprises:
A catalyst provided in the exhaust passage of the internal combustion engine;
A supply device for supplying a reducing agent to the catalyst;
An exhaust gas purification apparatus for an internal combustion engine comprising:
The supply device supplies the reducing agent toward a place where the mass of the exhaust gas is larger than a place where the mass of the exhaust gas is small.

Here, the exhaust density is not uniform, and there are places where the exhaust density is high and low. Then, the mass per unit volume is relatively large at locations where the exhaust density is high, and the mass per unit volume is relatively small at locations where the exhaust density is low. That is, the location where the exhaust mass is small may be a location where the exhaust density is relatively low. Further, the location where the mass of the exhaust is large may be a location where the density of the exhaust is relatively high. Further, the location where the exhaust mass is small and the location where the exhaust mass is large may be the location where the mass of the exhaust is the smallest and the location where the mass is the largest. That is, the reducing agent may be supplied toward a location where the mass of exhaust gas is the largest.

And, the portion where the mass of exhaust gas is large contains more components to be purified than the portion where the mass of exhaust gas is small. For this reason, in the location where the mass of exhaust gas is large, more reducing agent is required. On the other hand, by supplying the reducing agent toward a location where the mass of the exhaust gas is large, it is possible to supply more reducing agent to a location where more components to be purified are contained. Thereby, purification efficiency can be improved. Further, the supply amount of the reducing agent can be reduced. Moreover, since it becomes possible to supply the reducing agent according to the amount of the component to be purified, it is possible to suppress the excess reducing agent from adhering to the catalyst and reducing the purification rate. Moreover, it can suppress that an excessive reducing agent passes a catalyst. In this way, the reducing agent can be properly supplied.

In the present invention, the supply device includes an injection valve that injects the reducing agent,
The injection valve may be formed with an injection hole for injecting a reducing agent toward a portion where the mass of the exhaust gas is large.

By forming the nozzle holes in this way, it is possible to inject the reducing agent toward a location where there are more components to be purified. Thereby, purification efficiency can be improved.

In the present invention, the injection valve includes one or a plurality of injection holes, and the injection holes are formed so that the center of gravity of the reducing agent injected from each injection hole passes through a portion where the mass of the exhaust gas is large. May be.

Here, by providing a plurality of nozzle holes, the reducing agent is dispersed in a wider range. However, there are places where the concentration of the reducing agent is high and there are places where it is low. Moreover, even if there is one nozzle hole, depending on the shape of the nozzle hole, a place where the concentration of the reducing agent is high may be formed on the center side of the spray, or may be formed on the outer side. is there. And more reducing agent exists around the center of gravity of the injected reducing agent. The position of the center of gravity of the reducing agent may vary depending on the shape of the nozzle hole. For this reason, if the nozzle hole is formed so that the center of gravity of the reducing agent passes through a portion where the mass of the exhaust gas is large, more reducing agent can be supplied to a portion where there are more components to be purified.

In addition, when a plurality of nozzle holes are provided, each nozzle hole is formed so that a portion where the spray of the reducing agent injected from each nozzle hole passes through a portion where the mass of the exhaust gas is larger. May be. That is, since the concentration of the reducing agent is higher in the areas where the sprays overlap than in the areas where the sprays do not overlap, more reducing agent can be supplied. Moreover, you may form an injection hole so that the reducing agent injected from each injection hole may each pass through the location where the mass of exhaust_gas | exhaustion is larger. In any case, it is possible to supply more reducing agent to a location where there are more components to be purified. The center of gravity may be the mass center of the mass distribution of the reducing agent at a predetermined distance from the injection valve.

In the present invention, a plurality of the injection valves may be provided, and the injection valves may be arranged so that the reducing agent injected from each injection valve overlaps at a location where the mass of the exhaust gas is large.

There are more reducing agents at the locations where the reducing agents injected from the respective injection valves overlap. And in the location where the mass of exhaust gas is large, the spray overlaps, so that more reducing agent can be supplied to this location. That is, a larger amount of reducing agent can be supplied to locations where there are more components to be purified. In this case, the number of injection holes of each injection valve may be one or plural. When there is one nozzle hole, the place where the concentration of the reducing agent is high may be formed on the center side of the spray, or may be formed on the outer side. Moreover, the attachment position of each injection valve may be adjusted so that the position where the reducing agent injected from each injection valve overlaps becomes the mass center of the mass distribution of the reducing agent.

According to the present invention, the reducing agent can be properly supplied.

1 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a first embodiment. It is the figure which illustrated the form of spraying of the injection valve concerning Example 1. It is the figure which showed an example of the relationship between the mass distribution of the exhaust_gas | exhaustion in an exhaust passage, and the spray of the reducing agent injected from the injection valve. It is the figure which showed an example of the mass distribution of exhaust when a catalyst is seen from the upstream of an exhaust passage. FIG. 5 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a second embodiment. FIG. 6 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a third embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a fourth embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a fourth embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a fourth embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a fourth embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to a fourth embodiment. It is a figure which shows schematic structure of the conventional injection valve. It is a figure which shows schematic structure of the injection valve which concerns on Example 5. FIG. It is a figure which shows schematic structure of the other injection valve which concerns on Example 5. FIG. It is a figure which shows schematic structure of the injection valve provided with one injection hole. It is a figure which shows schematic structure of the other injection valve provided with one injection hole.

Hereinafter, specific embodiments of the exhaust gas purification apparatus for an internal combustion engine according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to the present embodiment. The internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders. The following embodiments can be similarly applied even to a gasoline engine.

The exhaust passage 2 is connected to the internal combustion engine 1. An injection valve 3 and a catalyst 4 are provided in the exhaust passage 2 in order from the upstream side in the exhaust flow direction.

The injection valve 3 injects a reducing agent. As the reducing agent, for example, a reducing agent derived from ammonia such as fuel (HC) or urea water can be used. What is used as the reducing agent depends on the type of the catalyst 4. Then, the reducing agent reacts with the catalyst 4. The injection hole of the injection valve 3 can be formed so that the spray R of the injection valve 3 has the following shape.

Here, FIG. 2 is a diagram illustrating the form of the spray R of the injection valve 3 according to the present embodiment. FIG. 2 shows a cross-sectional shape of the spray R of the reducing agent injected from the injection valve 3. This cross section is a cross section orthogonal to the central axis of the injection valve 3 at a predetermined distance from the injection valve 3. In FIG. 2, the inside of the region surrounded by the solid line indicates the range where the spray R from each nozzle hole exists. The broken line indicates the tip of the injection valve 3.

FIG. 2A shows a case where three nozzle holes are provided. In this case, three injection holes are arranged at equal intervals around the central axis of the injection valve 3. Therefore, three sprays R are formed at an equal angle around the central axis of the injection valve 3.

FIG. 2 (B) and FIG. 2 (C) are cases where four nozzle holes are provided. In the case of FIG. 2B, four injection holes are arranged at equal intervals around the central axis of the injection valve 3. For this reason, four sprays R are formed at equal angles around the central axis of the injection valve 3. In the case of FIG. 2C, three injection holes are arranged at equal intervals around the central axis of the injection valve 3, and further one is arranged on the central axis of the injection valve 3. Therefore, three sprays R are formed at an equal angle around the central axis of the injection valve 3, and one spray R is formed on the central axis of the injection valve 3.

2 (D) and 2 (E) show a case where five nozzle holes are provided. In the case of FIG. 2D, five injection holes are arranged at equal intervals around the central axis of the injection valve 3. For this reason, five sprays R are formed at equal angles around the central axis of the injection valve 3. In the case of FIG. 2 (E), four injection holes are arranged at equal intervals around the central axis of the injection valve 3, and one further is arranged on the central axis of the injection valve 3. For this reason, four sprays R are formed at an equal angle around the central axis of the injection valve 3, and one spray R is formed on the central axis of the injection valve 3.

FIG. 2 (F) and FIG. 2 (G) are cases where six nozzle holes are provided. In the case of FIG. 2 (F), six injection holes are arranged at equal intervals around the central axis of the injection valve 3. For this reason, six sprays R are formed at equal angles around the central axis of the injection valve 3. In the case of FIG. 2G, five injection holes are arranged at equal intervals around the central axis of the injection valve 3, and further one is arranged on the central axis of the injection valve 3. Therefore, five sprays R are formed at equal angles around the central axis of the injection valve 3, and one spray R is formed on the central axis of the injection valve 3.

FIG. 2 (H) shows a case where seven nozzle holes are provided. In this case, six injection holes are arranged at equal intervals around the central axis of the injection valve 3, and one further is arranged on the central axis of the injection valve 3. For this reason, six sprays R are formed at equal angles around the central axis of the injection valve 3, and one spray R is formed on the central axis of the injection valve 3.

In any case shown in FIG. 2, the center of gravity of the reducing agent is on an extension line of the central axis of the injection valve 3. This center of gravity may be the center of gravity or the center of mass of the reducing agent present in the cross section orthogonal to the central axis. That is, it is good also as a mass center of mass distribution of the spray R shown in FIG. Further, the center of gravity of the reducing agent may not be on an extension line of the central axis of the injection valve 3. Furthermore, the injection hole of the injection valve 3 may be one or two.

Examples of the catalyst 4 include an occlusion reduction type NOx catalyst, a selective reduction type NOx catalyst, an oxidation catalyst, and a three-way catalyst. Further, the catalyst 4 may be carried on a particulate filter. Further, a particulate filter may be provided upstream or downstream of the catalyst 4.

The internal combustion engine 1 configured as described above is provided with an ECU 10 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 10 controls the operation state of the internal combustion engine 1 according to the operation conditions of the internal combustion engine 1 and the request of the driver.

The ECU 10 is connected to an accelerator opening sensor 12 capable of detecting an engine load by outputting an electric signal corresponding to the amount of depression of the accelerator pedal 11, and a crank position sensor 13 for detecting the engine speed via electric wiring. Output signals from these sensors are input to the ECU 10. On the other hand, the injection valve 3 is connected to the ECU 10 via electric wiring, and the injection valve 3 is controlled by the ECU 10.

In this embodiment, for example, the injection valve 3 is assumed to inject urea water, and the catalyst 4 is a selective reduction type NOx catalyst. Then, the urea water injected from the injection valve 3 is hydrolyzed by the heat of the exhaust gas to become ammonia (NH ₃ ), and part or all of the urea water is adsorbed on the catalyst 4. This ammonia selectively reduces NOx. Then, ammonia is supplied to the catalyst 4 or adsorbed in advance, and the NOx is reduced when NOx passes through the catalyst 4.

By the way, in the exhaust passage 2, the exhaust density may vary depending on the location. That is, the mass per unit volume may vary depending on the location. For this reason, mass distribution arises. And in a location where mass is large, there are more NOx, HC, and CO than in a small location. For this reason, the amounts of NOx, HC, and CO flowing into the catalyst 4 are not uniform, and deviation occurs depending on the shape of the exhaust passage 2 and the like. In the catalyst 4, there are a portion where the exhaust mass is large and a portion where the exhaust mass is small. Therefore, when the reducing agent is uniformly supplied to the catalyst 4, excess or deficiency of the reducing agent may occur depending on the location. .

On the other hand, by supplying more reducing agent to a portion where the mass of exhaust gas is large, an amount of reducing agent corresponding to the mass of exhaust gas, that is, the amount of NOx, HC, CO can be supplied. it can.

Here, FIG. 3 is a diagram showing an example of the relationship between the mass distribution of the exhaust gas in the exhaust passage 2 and the spray R of the reducing agent injected from the injection valve 3. FIG. 3 is a cross section cut by a plane orthogonal to the central axis of the exhaust passage 2. An inner region surrounded by a broken line in FIG. 3 is a portion A where the mass of the exhaust gas is relatively large, and a region outside the broken line in FIG. 3 is a portion B where the mass of the exhaust gas is relatively small. In FIG. 3, the center of the location A where the exhaust mass is relatively large is assumed to be substantially equal to the central axis of the exhaust passage 2. The mass of exhaust gas may be the mass of exhaust gas per unit volume.

In this case, the injection valve 3 is attached so that the reducing agent is supplied toward the location A where the mass of the exhaust gas is relatively large. For this reason, the injection valve 3 is attached so that the central axis of the injection valve 3 and the central axis of the exhaust passage 2 downstream of the injection valve 3 coincide. For example, as shown in FIG. 1, the central axis of the injection valve 3 and the central axis of the exhaust passage 2 can be matched by using a portion where the exhaust passage 2 is bent. Then, the center of gravity of the reducing agent injected from the injection valve 3 exists on the central axis of the exhaust passage 2. That is, the center of gravity of the reducing agent passes through the portion A where the mass of the exhaust gas is relatively large. The concentration of the reducing agent is relatively high at and around the center of gravity of the reducing agent. For this reason, more reducing agent can be supplied to the location A where the mass of the exhaust gas is relatively large.

Further, the attachment position and the injection hole shape of the injection valve 3 may be adjusted so that the locations where the respective sprays R overlap each other pass the location A where the mass of the exhaust gas is relatively large. The direction of the central axis of the injection valve 3 and the flow direction of the exhaust need not be parallel. That is, it is only necessary that the center of gravity of the reducing agent passes through the location A where the exhaust mass is relatively large. Further, the injection hole of the injection valve 3 may be directed to the location A where the mass of the exhaust gas is relatively large. Further, the injection valve 3 may be formed with an injection hole for injecting the reducing agent toward the location A where the mass of the exhaust gas is relatively large.

It should be noted that the location A where the exhaust mass is relatively large may be displaced from the central axis of the exhaust passage 2. In this case, the attachment position of the injection valve 3 or the injection hole shape is adjusted according to the location A where the mass of the exhaust gas is relatively large. The mass distribution of the exhaust can be obtained in advance by experiments or simulations. Further, the exhaust gas mass distribution may change depending on the operating state of the internal combustion engine 1. For example, the exhaust mass distribution in a predetermined operation state is obtained, and the injection valve 3 is installed in accordance with the exhaust mass distribution. Then, the reducing agent is supplied in a predetermined operation state. The operating state is determined based on, for example, the engine speed and the engine load. This operation state may be an operation state in which the reducing agent can be supplied.

For example, as shown in FIG. 2, when there are a plurality of sprays R, the center of gravity of the reducing agent or the part where the sprays R overlap each other passes through the part A where the mass of the exhaust gas is relatively large. To do. In this way, by changing the mounting position, injection hole shape, and number of injection holes of the injection valve 3 according to the exhaust gas mass distribution, the exhaust mass is relatively larger than the location B where the exhaust amount is relatively small. More A reducing agent is supplied to the location A.

FIG. 4 is a diagram showing an example of the mass distribution of the exhaust when the catalyst 4 is viewed from the upstream side of the exhaust passage 2. This mass distribution is on the upstream end face of the catalyst 4. An inner region surrounded by a broken line in FIG. 4 is a portion A where the mass of the exhaust gas is relatively large, and a region outside the broken line in FIG. 4 is a portion B where the mass of the exhaust gas is relatively small. The mass of exhaust gas may be the mass of exhaust gas per unit volume.

In FIG. 4, there is a deviation between the center axis C of the catalyst 4 and the center D where the exhaust mass is relatively large. For example, if the exhaust passage 2 is bent just upstream of the catalyst 4, centrifugal force acts on the exhaust, resulting in a mass distribution as shown in FIG. 4.

Even in such a case, the mounting position, the injection hole shape, and the number of injection holes of the injection valve 3 are adjusted so that more reducing agent is supplied to the location A where the exhaust mass is relatively large. For example, the injection valve 3 may be attached to a portion where the cross-sectional area of the exhaust passage 2 increases toward the downstream side, and the reducing agent may be injected therefrom in parallel with the central axis of the catalyst 4.

Thus, according to the present embodiment, more reducing agent can be supplied to the location A where the mass of the exhaust gas is relatively large. That is, a reducing agent can be supplied according to the amount of components to be purified. For example, when a NOx catalyst is used as the catalyst 4 and urea water is used as the reducing agent, a larger amount of ammonia can be adsorbed in a portion where a lot of NOx passes, so that the NOx purification rate can be improved. it can. Further, ammonia can be prevented from passing through the catalyst 4. Further, when HC is supplied as a reducing agent, it is possible to suppress the HC from adhering to the catalyst 4 and preventing the exhaust gas from being purified. Furthermore, deterioration due to the temperature rise of the catalyst 4 can be suppressed. Moreover, it can suppress that the catalyst 4 is clogged with a particulate matter.

FIG. 5 is a diagram showing a schematic configuration of the exhaust gas purification apparatus for an internal combustion engine according to the present embodiment. FIG. 5A is a view showing the arrangement of the device, and FIG. 5B is a view of the exhaust passage 2 where the injection valve 3 is attached as viewed from the upstream side. In addition, about the same member as Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In this embodiment, an oxidation catalyst 41 and a particulate filter 42 are provided upstream of the injection valve 3. Further, a selective reduction type NOx catalyst 43 is provided downstream of the injection valve 3. The injection valve 3 is attached to a location where the exhaust passage 2 between the particulate filter 42 and the selective reduction type NOx catalyst 43 is narrowed. The injection valve 3 is attached so that its central axis is orthogonal to the central axis of the exhaust passage 2. The injection hole of the injection valve 3 is formed so that the concentration of the reducing agent injected from the injection valve 3 is high on the central axis of the injection valve 3 and decreases as the distance from the central axis increases. It is assumed that the portion where the mass of the exhaust is relatively large is on the central axis of the exhaust passage 2.

Even in the exhaust emission control device configured as described above, it is possible to supply more reducing agent to a location where the mass of the exhaust is relatively large. Further, the injection valve 3 can be attached even if the particulate filter 42 and the selective reduction type NOx catalyst 43 are close to each other. Moreover, since the disturbance of the exhaust gas becomes large at the location where the exhaust passage 2 is narrowed, atomization of the reducing agent can be promoted.

FIG. 6 is a diagram showing a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to the present embodiment. FIG. 6A is a diagram showing the arrangement of the apparatus, and FIG. 6B is a diagram of the particulate filter 42 viewed from the downstream side of the particulate filter 42. In addition, about the same member as Example 1 or Example 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In this embodiment, the injection valve 3 is attached so that the spray R from the injection valve 3 collides with the downstream end face of the particulate filter 42. For this reason, the injection valve 3 is attached to a portion downstream of the particulate filter 42 and having a smaller sectional area of the exhaust passage 2 toward the downstream side.

It should be noted that the portion where the mass of the exhaust is relatively large is on the central axis of the exhaust passage 2. Then, the reducing agent injection direction is determined so that the center of gravity of the reducing agent passes through a point where the downstream end surface of the particulate filter 42 and the central axis of the exhaust passage 2 intersect.

Even in the exhaust emission control device configured as described above, it is possible to supply more reducing agent to a location where the mass of the exhaust is relatively large. Further, the injection valve 3 can be attached even if the particulate filter 42 and the selective reduction type NOx catalyst 43 are close to each other. Further, since the temperature of the end face of the particulate filter 42 is high due to the heat of exhaust gas, for example, hydrolysis of urea water can be promoted.

7 to 11 are diagrams showing a schematic configuration of an exhaust gas purification apparatus for an internal combustion engine according to the present embodiment. FIG. 7A, FIG. 8A, and FIG. 9A are views of the catalyst 4 viewed from the lateral direction. 7B, FIG. 8B, FIG. 9B, FIG. 10, and FIG. 11 are views of the catalyst 4 viewed from the upstream side of the catalyst 4. FIG. In addition, about the same member as Example 1- Example 3, the same code | symbol is attached | subjected and description is abbreviate | omitted. 7 (B), FIG. 8 (B), FIG. 9 (B), FIG. 10, and FIG. 11 show the shapes of the sprays R, R1, and R2 when the exhaust passage 2 is assumed to be absent. .

In the present embodiment, the cross section of the catalyst 4 orthogonal to the exhaust flow direction is relatively long in one direction (vertical direction) and relatively short in the other direction (horizontal direction) orthogonal to the one direction. For example, the cross-sectional shape of the catalyst 4 may be oval or rectangular. The central axis of the exhaust passage 2 is shifted between the upstream side and the downstream side of the catalyst 4. That is, the exhaust passage 2 upstream of the catalyst 4 is located above the central axis of the catalyst 4, and the exhaust passage 2 downstream of the catalyst 4 is located below the central axis of the catalyst 4. Yes. In such a catalyst 4, the mass of the exhaust gas and the mass of the reducing agent tend to vary depending on the location.

Therefore, in the case shown in FIG. 7, the injection valve 3 is attached to the straight portion of the exhaust passage 2 upstream from the catalyst 4. The straight portion of the exhaust passage 2 is located upstream of the portion where the cross-sectional area of the exhaust passage 2 increases toward the downstream side in accordance with the shape of the catalyst 4. The injection valve 3 is attached so that its central axis is orthogonal to the central axis of the exhaust passage 2. It is assumed that the portion where the mass of the exhaust is relatively large is on the central axis of the exhaust passage 2.

Even in the exhaust emission control device configured as described above, it is possible to supply more reducing agent to a location where the mass of the exhaust is relatively large. Further, even if the cross-sectional area of the exhaust passage 2 is increased immediately upstream of the catalyst 4 toward the downstream side, a reducing agent corresponding to the mass of the exhaust gas flowing into the catalyst 4 is supplied. Moreover, a reducing agent can be supplied also to a location where the mass of exhaust gas is relatively small. Thus, the reducing agent can be supplied according to the mass of the exhaust.

Further, in the case shown in FIG. 8, the injection valve 3 is mounted on the upstream side of the catalyst 4 and on the downstream side of the portion where the cross section of the exhaust passage 2 becomes larger toward the downstream side. Then, the reducing agent is injected in parallel with the upstream end face of the catalyst 4 and in the major axis direction of the upstream end face. Further, as shown in FIG. 8 (B), the spray R1 near the extension line of the central axis of the injection valve 3 has a relatively high concentration, and the spray at a position away from the extension line of the central axis of the injection valve 3. A nozzle hole is formed so that the concentration of R2 is relatively low. That is, the concentration is higher on the center side of the spray. It is assumed that a portion having a relatively large exhaust mass is formed along the long axis of the catalyst 4.

Even in the exhaust emission control device configured as described above, it is possible to supply more reducing agent to a location where the mass of the exhaust is relatively large. Moreover, a reducing agent can be supplied also to another location. Thus, the reducing agent can be supplied according to the mass of the exhaust.

Further, in the case shown in FIG. 9, two injection valves 3 are mounted on the upstream side of the catalyst 4 and on the downstream side of the portion where the cross section of the exhaust passage 2 becomes larger on the downstream side. And in each injection valve 3, the reducing agent is injected in parallel with the upstream end face of the catalyst 4 and in the major axis direction of the upstream end face. In addition, nozzle holes and the like are formed so that the spray R from each injection valve 3 is uniform.

In the exhaust emission control device configured in this way, the concentration of the reducing agent increases because more reducing agent exists at the locations where the sprays R overlap. By superimposing the sprays R at locations where the exhaust mass is relatively large, more reducing agent can be supplied to locations where the exhaust mass is relatively large. Moreover, a reducing agent can be supplied also to another location. Thus, the reducing agent can be supplied according to the mass of the exhaust.

In the case shown in FIG. 10, the injection valve 3 is attached on the upstream side of the catalyst 4 and on the downstream side of the portion where the cross section of the exhaust passage 2 becomes larger toward the downstream side. Further, the injection valve 3 injects a reducing agent in a diagonal direction parallel to the upstream end face of the upstream end face of the catalyst 4. Further, the spray R1 near the extension of the central axis of the injection valve 3 has a relatively high concentration, and the spray R2 away from the extension of the central axis of the injection valve 3 has a relatively low concentration. A nozzle hole or the like is formed.

Further, in the case shown in FIG. 11, two injection valves 3 are attached opposite to the upstream side of the catalyst 4 and the downstream side of the portion where the cross section of the exhaust passage 2 becomes larger toward the downstream side. Further, the injection valve 3 injects a reducing agent in a diagonal direction parallel to the upstream end face of the upstream end face of the catalyst 4. In addition, nozzle holes and the like are formed so that the spray R from each injection valve 3 is uniform.

Also in the exhaust gas purification apparatus configured as described above, since a larger amount of the reducing agent is present at the portion where the spray R overlaps, more reducing agent can be supplied to the portion where the mass of the exhaust gas is relatively large. Moreover, a reducing agent can be supplied also to another location. Thus, the reducing agent can be supplied according to the mass of the exhaust.

FIG. 12 is a diagram showing a schematic configuration of a conventional injection valve 3. FIG. 12A is a cross-sectional view when the tip of the injection valve 3 is cut along the central axis, and FIG. 12B is a diagram of the tip of the injection valve 3 as viewed from an extension line of the central axis. FIG. 12C shows the concentration distribution of the reducing agent at a predetermined distance from the injection valve 3.

The injection hole 31 of the injection valve 3 is formed so that the cross section orthogonal to the central axis of the injection valve 3 is rectangular. The rectangular length of this cross section is longer toward the tip side of the injection valve 3. Moreover, the width of the rectangle of the cross section is constant. For this reason, the spray R is formed at a predetermined angle. The angles of the nozzle hole 31 and the spray R are smaller than the angles of the nozzle hole 31 and the spray R shown in FIG.

In the injection valve 3 configured in this manner, when the reducing agent passes through the injection hole 31, a large amount of the reducing agent flows along the wall surface of the injection hole 31, so that the cross section of the spray R is shown in FIG. ), For example, an ellipse. A spray R1 having a relatively high concentration is formed at both ends of the long axis of the ellipse, and a spray R2 having a relatively low concentration is formed on an extension line of the central axis of the injection valve 3. For this reason, although the center of gravity of the reducing agent is on the extension line of the central axis of the injection valve 3, the amount of the reducing agent supplied on the extension line of the central axis is small.

On the other hand, by adjusting the shape of the injection hole 31, a large amount of reducing agent can be supplied on the extended line of the central axis of the injection valve 3.

FIG. 13 is a diagram showing a schematic configuration of the injection valve 3 according to the present embodiment. FIG. 13A is a cross-sectional view when the tip of the injection valve 3 is cut along the central axis, and FIG. 13B is a view of the tip of the injection valve 3 as viewed from an extension line of the central axis. FIG. 13C is a view showing the concentration distribution of the reducing agent at a predetermined distance from the injection valve 3.

In the injection valve 3 shown in FIG. 13, the injection hole 31 is formed so that the angle of the injection hole 31 and the spray R is larger than that of the injection valve 3 shown in FIG. That is, comparing the injection valve 3 shown in FIG. 12 with a cross-sectional shape, the injection valve 3 shown in FIG. Note that the rectangular width of the cross section is the same as that shown in FIG.

When the nozzle hole 31 is formed in this way, the reducing agent peels from the nozzle hole 31 when the reducing agent passes through the nozzle hole 31. As a result, more reducing agent flows through the central axis side of the injection valve 3. As a result, a spray R1 having a relatively high concentration is formed on the extension line of the central axis of the injection valve 3, and a spray R2 having a relatively low concentration is formed at both ends. In this way, the concentration of the reducing agent on the extension line of the central axis of the injection valve 3 can be increased. Then, by directing the injection hole 31 to a location where the mass of the exhaust is large, most of the injected reducing agent is directed to a location where the mass of the exhaust is large. For this reason, more reducing agent can be supplied to the location where the mass of exhaust gas is large. In other words, the concentration of the reducing agent on the extension line of the central axis of the injection valve 3 can be increased by setting the angle of the injection hole 31 so that the reducing agent is peeled off from the wall surface of the injection hole 31.

FIG. 14 is a diagram showing a schematic configuration of another injection valve 3 according to the present embodiment. FIG. 14A is a cross-sectional view when the tip of the injection valve 3 is cut along the central axis, and FIG. 14B is a diagram of the tip of the injection valve 3 as viewed from an extension line of the central axis. FIG. 14C shows the concentration distribution of the reducing agent at a predetermined distance from the injection valve 3.

In the injection valve 3 shown in FIG. 14, the injection hole 31 is provided at a position shifted from the central axis of the injection valve 3. Thereby, the spray R1 having a relatively high concentration is formed on the center side, and the spray R2 having a relatively low concentration is formed on both ends. In this way, the concentration of the reducing agent on the extension line of the injection hole 31 of the injection valve 3 can be increased. Then, by directing the injection hole 31 to a location where the mass of the exhaust is large, most of the injected reducing agent is directed to a location where the mass of the exhaust is large. For this reason, more reducing agent can be supplied to the location where the mass of exhaust gas is large.

FIG. 15 is a diagram showing a schematic configuration of the injection valve 3 having one injection hole 31. FIG. 15A is a cross-sectional view when the tip of the injection valve 3 is cut along the central axis, and FIG. 15B shows the concentration distribution of the reducing agent at a predetermined distance from the injection valve 3. It is.

The injection valve 3 shown in FIG. 15 is formed such that the reducing agent advances in the direction of the arrow in FIG. If it does so, more reducing agents will distribute | circulate the position away from the center axis | shaft of the injection valve 3. FIG. Thereby, the spray R2 having a relatively low concentration is formed on the extended line of the central axis of the injection valve 3, and the spray R1 having a relatively high concentration is formed around the spray R2.

On the other hand, FIG. 16 is a diagram showing a schematic configuration of another injection valve 3 having one injection hole 31. FIG. 16A is a cross-sectional view when the tip of the injection valve 3 is cut along the central axis, and FIG. 16B shows the concentration distribution of the reducing agent at a predetermined distance from the injection valve 3. It is.

The injection valve 3 shown in FIG. 16 is formed such that the reducing agent advances in the direction of the arrow in FIG. If it does so, more reducing agents will distribute | circulate on the extension line | wire of the center axis | shaft of the injection valve 3. FIG. As a result, a spray R1 having a relatively high concentration is formed on the extension line of the central axis of the injection valve 3, and a spray R2 having a relatively low concentration is formed therearound.

Thus, the concentration distribution of the reducing agent also changes depending on the shape of the injection valve 3. Then, by directing the nozzle hole 31 to a location where the mass of the exhaust is large, most of the injected reducing agent is directed to a location where the mass of the exhaust is large. For this reason, more reducing agent can be supplied to the location where the mass of exhaust gas is large.

Further, by selecting the injection valve 3 in accordance with the location where the exhaust mass becomes large or changing the mounting position, it is possible to supply more reducing agent to the location where the exhaust mass is large.

1 Internal combustion engine 2 Exhaust passage 3 Injection valve 4 Catalyst 10 ECU
11 Accelerator pedal 12 Accelerator opening sensor 13 Crank position sensor 31 Injection hole 41 Oxidation catalyst 42 Particulate filter 43 Selective reduction type NOx catalyst

Claims

A catalyst provided in the exhaust passage of the internal combustion engine;
A supply device for supplying a reducing agent to the catalyst;
An exhaust gas purification apparatus for an internal combustion engine comprising:
The supply device is an exhaust purification device of an internal combustion engine that supplies a reducing agent toward a location where the mass of exhaust gas is larger than a location where the mass of the exhaust is small.
The supply device includes an injection valve that injects the reducing agent,
The exhaust purification device for an internal combustion engine according to claim 1, wherein the injection valve is formed with an injection hole for injecting a reducing agent toward a portion where the mass of the exhaust gas is large.
The injection valve includes one or a plurality of injection holes, and the injection holes are formed such that the center of gravity of the reducing agent injected from each injection hole passes through a portion where the mass of the exhaust gas is large. 2. An exhaust gas purification apparatus for an internal combustion engine according to 1.
3. The exhaust gas purification apparatus for an internal combustion engine according to claim 2, wherein a plurality of the injection valves are provided, and the respective injection valves are arranged such that a reducing agent injected from each injection valve overlaps at a location where the mass of the exhaust gas is large.