JP2009156069A - Exhaust gas purification device for internal combustion engine - Google Patents

Abstract

The present invention provides an exhaust gas purification device for an internal combustion engine in which accumulation of an additive in an injection passage is suppressed.
An exhaust gas purifying apparatus for an internal combustion engine according to the present invention is provided with an additive adhesion suppressing means for suppressing an additive from adhering to a wall surface of an injection passage 26a. Prevented accumulation.
[Selection] Figure 2

Description

  The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine having a structure for injecting fuel required for reaction of a catalyst.

To purify exhaust gas from diesel engine vehicles (vehicles), in order to prevent NOx (nitrogen oxides) and PM (particulate matter) contained in the exhaust gas of diesel engines from being released into the atmosphere, An exhaust gas purifier combined with a selective reduction type NOx catalyst, a diesel particulate filter, or the like is used.
In such an exhaust gas purification device, a catalyst such as an oxidation catalyst, an occlusion type NOx catalyst or a selective reduction type NOx catalyst, called a pre-stage catalyst, is provided in an exhaust pipe for exhausting exhaust gas exhausted from the engine to the outside. A structure in which a fuel addition valve (which adds a reducing agent) or the like for injecting fuel required for the reaction of the catalyst is provided on the upstream side, for example, upstream of the oxidation catalyst.

By the way, in order for the fuel addition valve to function properly at all times, avoid using the fuel addition valve at a temperature exceeding the heat resistance temperature, or avoid generating a digipot at the tip of the fuel addition valve, which may cause injection clogging. It is required to do.
For this purpose, it is effective to keep the fuel addition valve away from the exhaust gas flow so that the tip portion where the fuel is injected is not exposed to the high-temperature exhaust gas. Therefore, in the exhaust gas purification device, as disclosed in Patent Document 1, an exhaust passage formed by a recess or a cylindrical portion is separately provided in the exhaust pipe, and fuel is supplied from the fuel addition valve through the injection passage. A structure for injecting into the exhaust pipe has been proposed. In many cases, one end of the injection passage opens into the exhaust pipe, and a fuel addition valve is installed at the other end. The fuel injected from the fuel addition valve is introduced into the exhaust pipe from a point away from the exhaust pipe. A structure for spraying is used.
JP 2004-44483 A

By the way, in such a structure that injects fuel from a point away from the exhaust pipe, since the injection passage is retracted from the exhaust pipe, the flow of the exhaust gas that flows through the exhaust pipe does not easily reach the inside of the injection passage. . That is, a stagnant portion is likely to occur in the injection passage. For this reason, the fuel injected into the injection passage tends to stop in the injection passage.
Therefore, it is conceivable that the fuel injected into the injection passage adheres to the wall surface of the injection passage without evaporating, and the attached fuel serves as a binder to allow soot contained in the exhaust gas to adhere to the injection passage. End up.

Therefore, every time fuel is injected from the fuel addition valve, soot gradually accumulates on the wall surface, and the inside of the injection passage may be blocked with soot. For this reason, the reaction of the catalyst is affected, and the exhaust gas purification performance may not be maintained.
Accordingly, an object of the present invention is to provide an exhaust gas purifying device for an internal combustion engine in which accumulation of additives in an injection passage is suppressed.

In order to achieve the above object, the invention described in claim 1 employs additive adhesion suppressing means for suppressing the adhesion of the additive to the wall surface of the injection passage.
With this configuration, adhesion of the additive to each part of the injection passage is suppressed, and accumulation of the additive in the injection passage can be prevented. As a result, the additive injection valve can always inject well, and the exhaust gas purification performance is always well maintained.

  The invention according to claim 2 further includes an additive injected from the additive injection valve in the injection passage in the additive adhesion suppressing means so as to effectively prevent accumulation of the additive with a simple structure. Adopting a structure with a radiator that is arranged so as not to interfere with the radiator and a heat source that supplies heat to the radiator, the heat adsorbed from the radiator is used to dry the additive adhering to the radiator Alternatively, it is possible to suppress adhesion to each part of the injection passage by burning.

The invention according to claim 3 is also arranged in the additive adhesion suppressing means so as to cover the wall surface of the injection passage without interfering with the additive injected from the additive injection valve in the injection passage. The structure including the vibration body and the vibration source section that vibrates the vibration body is employed to prevent the additive from adhering to each part of the injection passage due to the vibration of the vibration body.
In the invention according to claim 4, the additive adhesion suppressing means can be more effectively prevented from depositing the additive without interfering with the additive injected from the additive injection valve in the injection passage. A vibration radiator that is arranged so as to cover the wall surface of the injection passage, a heat source part that supplies heat to the heat radiator, and a vibration source part that vibrates the heat radiator, and attaches the two ridges. It was set as the structure which uses together the technique which makes it difficult to do.

According to the first aspect of the present invention, since the adhesion of the additive to each part of the injection passage is suppressed, it is possible to prevent the additive from accumulating in the injection passage.
As a result, the injection from the additive injection valve can always be performed satisfactorily, and the exhaust gas purification performance can always be maintained satisfactorily.
According to the second aspect of the present invention, the adhering of the additive to each part of the injection passage can be suppressed with a simple structure in which the additive is dried or burned out using the radiator. Therefore, it is possible to prevent the additive from accumulating in the injection passage.

According to the third aspect of the present invention, it is possible to suppress adhesion of the additive to each part of the injection passage with a simple structure that makes it difficult for the additive to adhere using the vibrating body. Therefore, it is possible to prevent the additive from accumulating in the injection passage.
According to the invention of claim 4, the additive is prevented more effectively from being deposited in the injection passage by combining the technique for burning out the additive and the technique for making it difficult to adhere soot by vibration. be able to.

Hereinafter, the present invention will be described based on the first embodiment shown in FIG. 1 and FIG.
FIG. 1 shows an exhaust system of a diesel engine (internal combustion engine). In the figure, 1 is an engine body of a diesel engine, 1a is an exhaust manifold (only part of which is shown), and 2 is a turbocharger connected to an outlet of the exhaust manifold 1a, for example, a turbocharger. Show.

An exhaust gas purification device 3 is provided at the exhaust outlet of the turbocharger 2. In this exhaust gas purification device 3, for example, NOx (nitrogen oxide) in exhaust gas is occluded, and NOx removal system 3a for reducing and removing NOx occluded regularly and PM (particulate matter) are collected. The apparatus which combined PM collection system 3b to be used is used.
For example, the NOx removal system 3a includes a catalytic converter 6 in which an oxidation catalyst 5 (corresponding to the catalyst of the present application), which is connected in a downward direction from an exhaust outlet of the turbocharger 1a, is incorporated. A catalytic converter 9 having a built-in storage type NOx catalyst 8 connected laterally after the catalytic converter 6 and a fuel addition valve 23 for supplying fuel for catalytic reaction to an oxidation catalyst 5 described later (additive injection of the present application) In combination with a valve). The collection system 3b employs a configuration in which a catalytic converter 12 having a particulate filter 11 incorporated therein is connected to the catalytic converter 9. An exhaust pipe portion 15 (corresponding to the exhaust pipe of the present application) for guiding exhaust gas exhausted from the diesel engine (engine body 1) to the outside from the catalytic converters 6, 9, 12 and the connection portion 13 connecting the converters. Is configured.

  Among these, the vertical cylindrical housing 17 accommodating the oxidation catalyst 5 of the catalytic converter 6 is formed, for example, in an L shape on the upper side, and an inlet portion 17a connected to the upper turbocharger 2 is disposed sideways. ing. The outlet portion 17b communicating with the catalytic converter 9 is disposed downward. The housing 17 forms a bent portion 15a bent in an L shape at a point immediately after the exhaust side of the diesel engine in the exhaust pipe portion 15. The oxidation catalyst 5 is installed at a point directly below the bent portion 15a.

  The fuel addition valve 23 (additive injection valve) is provided at a point immediately above the oxidation catalyst 5, for example, a wall portion on the outer peripheral side of the bent portion 15 a in order to inject fuel into the oxidation catalyst 5. The fuel addition valve 23 has a fuel injection portion 23a for injecting fuel at the tip. The fuel addition valve 23 is installed by using the pedestal 24 so that the fuel injection portion 23a at the tip is retracted from the bent portion 15a. The installation structure of the fuel addition valve 23 is shown enlarged in FIG.

  The installation structure of the fuel addition valve 23 will be specifically described. The pedestal 24 is constituted by, for example, a columnar pedestal member. Among these, a valve mounting hole 25 extending to the middle stage is formed in the upper center of the base 24. In the center of the lower part, a cylindrical recess 26 is formed continuously from the lower end of the valve mounting hole 25 to the lower end of the base member. Further, a flange 27 is formed on the peripheral edge of the lower portion of the base 24 so as to surround the recess 26. The pedestal 24 is fixed to the outer peripheral portion of the bent portion 15a by screwing the flange 27 to the opening edge portion of the valve attachment port 19 formed in the bent portion 15a via the gasket 19a.

  The fuel addition valve 23 is fixed by inserting a distal end portion into the valve mounting hole 25 of the pedestal 24 and pressing the main body portion 23b against the upper surface of the pedestal 24 with a pressing member (not shown). The fuel injection portion 23 a at the tip of the fuel addition valve 23 faces the recess 26. As a result, the fuel required for the reaction of the oxidation catalyst 5 (catalyst) from a point away from the exhaust gas flow (for example, light oil as a diesel engine fuel) is injected into the exhaust pipe portion 15 through the recess 26, that is, It is made to inject toward the inlet end surface of the oxidation catalyst 5. That is, by installing the fuel addition valve 23 at a position away from the main flow of exhaust gas, the fuel injection unit 23a can perform injection without being exposed to a high-temperature exhaust gas flow. This prevents the heat resistance temperature of the fuel addition valve 23 from being exceeded or the fuel addition valve 23 from becoming a temperature at which a digipot is likely to be generated. A cooling water passage 28 is formed inside the pedestal 24 to further prevent the temperature from exceeding, and the fuel addition valve 23 is also cooled by the cooling water (water cooling).

  The fuel injected from the fuel addition valve 23 generates a reducing agent by the reaction of the oxidation catalyst 5, and the reducing agent removes NOx and SOx stored in the storage-type NOx catalyst 8. The PM collected by the particulate filter 11 is burned and removed by the temperature rise obtained by the reaction No. 5. Therefore, the fuel addition valve 23 is used when a catalytic reaction such as NOx or SOx reduction or PM combustion removal is required during operation of the diesel engine by a control unit that controls the diesel engine, for example, an ECU (not shown). Fuel is injected.

  In addition, a soot adhesion suppressing portion 30 (corresponding to the additive adhesion suppressing means of the present application) that suppresses soot contained in the exhaust gas from adhering to the wall surface of the injection passage 26a is provided in the injection passage 26a. For example, the soot adhesion suppressing part 30 has a structure in which a radiator 32 is disposed in the injection passage 28, heat is supplied from the heat source part to the radiator 32, and the soot is dried by heat radiated from the radiator 32. Is used.

  The structure will be described with reference to FIG. 2. The heat radiating body 32 is formed from a highly conductive member, for example, a thin plate made of steel plate or aluminum, into a bottomed cylindrical shape covering the wall surface of the recess 26 from the inside. It is. The heat radiating body 32 is fixed to the opening edge of the valve mounting port 19 by, for example, an annular stop member 34, the end face of the heat radiating body 32 is close to the end face of the concave portion 26, and the outer peripheral surface of the heat radiating body 32 is the side surface of the concave portion 26. It is close. A through hole 35 is formed in the center of the end wall of the heat radiating body 32 facing the fuel injection section 23a to allow the fuel injected from the fuel injection section 23a to pass through. The injection passage 26a is used. Thus, the fuel injected from the fuel addition valve 23 can be injected into the bent portion 15a (in the exhaust pipe) through the injection passage 26a without interfering with the radiator 32.

  For example, a structure for supplying heat of exhaust gas of a diesel engine is used for the heat source section that supplies heat to the radiator 32. In the same structure, as shown in FIG. 2, for example, an annular flange portion 32a is formed at the opening side end of the radiator 32, and the flange portion 32a is bent in the bent portion 15a (in the exhaust pipe). The structure which takes in the heat | fever of exhaust gas from the flange part 32a arrange | positions along the wall surface of the outer peripheral side of 15a is used. That is, the flange portion 32 a is used as a heat receiving portion 37 as a heat source portion, so that the heat of the exhaust gas flowing in the bent portion 15 a is transmitted to the heat radiating body 32 and is radiated from each portion of the heat radiating body 32. As a result, the radiator 32 and the internal injection passage 26a are continuously heated to a high temperature so that the evaporated fuel stagnated in the injection passage 26a is gasified or the soot that has been made sticky by the evaporated fuel is dried. I will let you. Thus, the soot is prevented from adhering to the injection passage 26a.

That is, the same action will be explained. Exhaust gas exhausted from the diesel engine during operation of the diesel engine passes through the exhaust manifold 1a, the turbocharger 2, the oxidation catalyst 5, the occlusion-type NOX catalyst 8, and the particulate filter 11 to the outside air. Exhausted.
NOx and SOx contained in the exhaust gas are occluded in the occlusion-type NOx catalyst 8, and PM is also collected by the particulate filter 11.

At this time, the heat of the exhaust gas is transmitted to each part of the bottomed cylindrical radiator 32 through the flange portion 32a (heat receiving portion 37). Thereby, not only each part of the radiator 32 but also the inside of the injection passage 26a is heated to a high temperature by the heat of the exhaust gas radiated from the radiator 32.
It is time to remove the stored NOx or SOx and the collected PM, and fuel is injected from the fuel injection portion 23a of the fuel addition valve 23 to remove them.

Then, the fuel is injected to the inlet end face of the oxidation catalyst 5 through the through hole 35 and the heat radiator 32 (injection passage 26a) as shown in FIGS. α indicates the fuel injection flow.
Here, since the injection passage 26a is formed at a point retracted from the exhaust gas flow, the exhaust gas hardly flows and stagnation is likely to occur. Due to this stagnation, the fuel evaporated in the injection passage 26a remains in the injection passage 26a as it is, and the fuel serves as a binder to try to attach soot P contained in the exhaust gas to the surroundings.

At this time, since the injection passage 26a is heated to a high temperature using the heat of the exhaust gas as a heat source by the radiator 32 provided so as to surround the injection passage 26a, the fuel evaporated in the injection passage 26a is gasified. Moreover, the soot P that is sticky by the evaporated fuel is dried by evaporating the fuel component.
Since the function of the dried soot P is eliminated as a binder for the evaporated fuel, it is difficult to adhere to the wall surface of the injection passage 26a. For this reason, the dried soot P falls, reaches the inside of the exhaust pipe, that is, into the bent portion 15a, and is directly introduced into the exhaust gas flow flowing through the bent portion 15a.

Therefore, adhesion of soot P to each part of the injection passage 26a is suppressed, and soot P can be prevented from accumulating in the injection passage 26a.
Therefore, the fuel addition valve 23 can always perform fuel injection well and can always maintain good exhaust gas purification performance. Moreover, the structure for drying the basket P using the radiator 32 is a simple structure. In particular, when a structure (heat receiving portion 37) that takes in heat of the exhaust gas by extending a part of the radiator 32 into the bent portion 15a as the heat source portion is adopted, the heat required for drying the soot P can be easily obtained. can do.

In addition, since the heat radiator 32 has the shape of the inner surface of the recess 26, that is, the shape surrounding the injection passage 26a, there is an advantage that the injection passage 26a can be easily heated to a high temperature.
FIG. 3 shows a second embodiment of the present invention.
The second embodiment does not use the structure that takes in the heat of the exhaust gas from the flange (heat receiving portion) as in the first embodiment, but the heat radiator 32 itself functions as an electric heater, and the heat radiator 32. The heat is dissipated from the heat (heat generation).

Specifically, as shown in FIG. 3, as a heat source unit, an energization circuit 40 is provided outside the exhaust pipe, and the energization circuit 40 and the heat radiating body 32 are connected to each other with the power supplied from the energization circuit 40. The radiator 32 functions as an electric heater so that heat is radiated from each part of the radiator 32.
Even in this case, as in the first embodiment, the soot P adhering to the evaporated fuel is dried to prevent the soot P from adhering to each part in the injection passage 26a, thereby preventing the soot P from accumulating. it can. In this case, the temperature of the radiator may be further increased to burn the soot P itself. Of course, as shown by a two-dot chain line in FIG. 3, a structure for taking in heat of the exhaust gas from the flange 37 (heat receiving portion) as in the first embodiment may be used together.

However, in FIG. 3, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
4 and 5 show a third embodiment of the present invention.
The present embodiment does not use the structure in which the adhesion of the soot P is thermally eliminated as in the first and second embodiments, but the structure in which the soot adhesion is eliminated by vibration. Is used.

  That is, the wrinkle adhesion suppressing unit 30 of the present embodiment uses a vibrating body 45 having substantially the same outer shape as that used in the first embodiment, for example, instead of the radiator, and the resonance structure 50 as a vibration source unit. The structure which gives vibration to the vibrating body 45 is used. Specifically, the vibrating body 45 is formed in a bottomed cylindrical shape from a thin plate made of, for example, aluminum or steel plate, as shown in FIG. A flange 46 is formed at the opening edge. At the base of the flange 46, for example, a plurality of notches 47 are formed, and the bottomed cylindrical main body 45a is vertically moved with respect to the flange 46 by using the base portion having reduced rigidity. And it is easy to swing left and right.

  As shown in FIG. 4, the resonance structure 50 has a structure in which the flange 46 is fixed together with the flange 27, the gasket 19a, and the opening edge of the valve attachment port 19, and the main body 45a is installed so as to be able to vibrate. . That is, the main body 45a of the vibrating body 34 can vibrate with the base of the flange 46 as a fulcrum. Thereby, when the vibration of the engine body 1 generated by the operation of the diesel engine is applied from the exhaust pipe portion 15 to the vibrating body 45, the main body portion 45a of the vibrating body 45 resonates as indicated by the arrow direction x in FIG.

When the vibrating body 45 vibrates in this way, the stick P that stops in the ejection passage 26 a is prevented from adhering to the vibrating body 45. That is, it is possible to suppress the soot P from adhering to the injection passage 26 a even by the vibration of the vibrating body 45.
Therefore, as in the first and second embodiments, the soot P can be prevented from accumulating in the injection passage 26a. Moreover, the structure using the vibrating body 45 is also simple. In addition, since the vibration body 45 has a structure in which a portion having a low rigidity is formed in a part of the vibration body 45 and is resonated by vibration applied from the engine body 1, a simple structure is sufficient. Of course, instead of resonating with the vibration of the engine body 1, the vibrating body 45 may be separately oscillated using a vibrating device.

However, in FIG. 4 and FIG. 5, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 6 shows a fourth embodiment of the present invention.
This embodiment uses the technology described in the first and second embodiments to dry the cocoon P and make it difficult to attach the heel P, and the vibration described in the third embodiment. The structure which combined the technique which makes it hard to adhere the soot P was used.

  Specifically, the wrinkle adhesion suppressing unit 30 of the present embodiment employs a structure in which an energization circuit 60 is connected to a resonable cylindrical vibrating body 45 shown in FIG. Thus, the vibrating body 45 is heated. That is, the vibrating body 45 not only resonates due to the vibration of the engine body 1 but also heats the injection passage 26a by heat radiation from each part of the vibrating body 45 caused by energization.

Then, in the injection passage 26a, an action in which the two functions are synergistically generated is to dry the bag P and drop it by vibration.
Therefore, the combination of the technique for drying the soot P and the technique for preventing the soot P from adhering by vibration can more effectively prevent the soot P from being deposited in the injection passage 26a. Of course, in the technique for drying the cocoon P, a structure that takes in heat using a flange (heat receiving portion) as shown by a two-dot chain line in FIG. 2 or FIG. 3 may be used.

However, in FIG. 6, the same parts as those of the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In addition, this invention is not limited to any embodiment mentioned above, You may implement in various changes within the range which does not deviate from the main point of this invention. For example, in the above-described embodiment, drying or vibration is used to make it difficult to attach soot to the injection passage. However, the present invention is not limited to this, and soot may be made difficult to attach to the injection passage.

  In the above-described embodiment, an example is given in which the present invention is applied to an exhaust gas purifying apparatus in which an oxidation catalyst is used as a catalyst immediately downstream of the bent portion, and an occlusion-type NOX catalyst and a particulate filter are provided downstream thereof. The exhaust gas purifying apparatus of other purification methods, for example, a storage type NOX catalyst is used as a catalyst immediately downstream of the bent portion, a particulate filter is provided downstream thereof, and an addition valve is provided upstream of the storage type NOX catalyst. The exhaust gas purification system also uses an NOx storage catalyst as a catalyst immediately downstream of the bent part, an NOx storage catalyst, an oxidation catalyst, and a particulate filter downstream of it, and an addition valve upstream of the NOx storage catalyst. The present invention may be applied to an exhaust gas purifying device or an exhaust gas purifying device provided with a selective reduction catalyst or a particulate filter directly downstream of an additive injection valve.

  Further, in the above-described embodiment, the fuel is used as the additive. However, any material may be used as long as it is supplied to the catalyst. For example, light oil, gasoline, ethanol, dimethyl ether, natural gas, propane gas, urea as a reducing agent. , Ammonia, hydrogen, carbon monoxide, etc. Further, a substance other than the reducing agent may be used. For example, air for cooling the catalyst, nitrogen, carbon dioxide, etc., air or ceria for promoting combustion removal of soot collected in the particulate filter, and the like may be used. In addition to the cone shape, the fuel addition valve 23 may be a flat or fan-shaped additive injection valve or an additive injection valve in which an additive is injected from a plurality of injection holes.

  Furthermore, although one embodiment has been described using soot as the deposit in the injection passage, any substance may be applied as long as it is a substance contained in the exhaust gas or in the additive and is deposited as a solid.

1 is a partially sectional side view showing a structure of an exhaust gas purification apparatus according to a first embodiment of the present invention. The sectional side view which expands and shows the part in which the fuel addition valve of the same apparatus was installed. The sectional side view which shows the principal part of the exhaust-gas purification apparatus which concerns on the 2nd Embodiment of this invention. The sectional side view which shows the principal part of the exhaust-gas purification apparatus which concerns on the 3rd Embodiment of this invention. The perspective view which shows the external appearance of the vibrating body of the apparatus. The sectional side view which shows the principal part of the exhaust-gas purification apparatus which concerns on the 4th Embodiment of this invention.

Explanation of symbols

1 Engine body 3 Exhaust gas purification device 5 Oxidation catalyst (catalyst)
15 Exhaust pipe (exhaust pipe)
23 Fuel addition valve (additive injection valve)
26a Fuel injection path (injection path)
30 Wrinkle adhesion suppression part (wrinkle adhesion suppression means)
32 Radiator 32a Flange (heat receiving part)
37 Heat receiving part (heat source part)
40 Energizing circuit 45 Vibrating body 50 Resonant structure (vibration source)
P 煤

Claims (4)

An exhaust pipe for guiding exhaust gas exhausted from the engine to the outside;
A catalyst housed in the exhaust pipe;
An additive injection valve located upstream of the catalyst for supplying the additive to the catalyst;
The additive injection valve is provided on one end side, the other end side communicates with the exhaust pipe and an injection passage through which the additive is injected from the additive injection valve;
An exhaust gas purifying device for an internal combustion engine, comprising: additive adhesion suppressing means for suppressing the additive from adhering to the wall surface of the injection passage. The additive adhesion suppressing means is
A radiator disposed in the injection passage so as not to interfere with the additive injected from the addition valve;
The exhaust gas purifying device for an internal combustion engine according to claim 1, further comprising: a heat source unit that supplies heat to the heat radiating body. The additive adhesion suppressing means is
A vibrating body arranged in the injection passage so as to cover the wall surface of the injection passage without interfering with the additive injected from the additive injection valve;
The exhaust gas purifying device for an internal combustion engine according to claim 1, further comprising: a vibration source unit that vibrates the vibrating body. The additive adhesion suppressing means is
An oscillating heat dissipating member disposed in the injection passage so as to cover the wall surface of the injection passage without interfering with the additive injected from the additive injection valve;
A heat source for supplying heat to the radiator,
The exhaust gas purifying device for an internal combustion engine according to claim 1, further comprising: a vibration source unit that vibrates the heat radiator.

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