JP4985976B2 - Exhaust gas purification device for internal combustion engine - Google Patents

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 from 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 according to claim 1 is located on the exhaust upstream side of the catalyst, an exhaust pipe that guides exhaust gas exhausted from the engine to the outside, a catalyst housed in the exhaust pipe section, and An additive injection valve for supplying an additive to the catalyst, an additive injection valve provided on one end side, an injection passage through which the other end side communicates with the exhaust pipe and the additive is injected from the additive injection valve, and an injection passage And a vibration body that is disposed so as to cover the wall surface of the injection passage without interfering with the additive injected from the additive injection valve, and that resonates with engine vibration generated by engine operation. It was adopted.
According to this configuration, the adhesion of the additive to each part of the injection passage is suppressed by the vibration of the vibrating body. 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 is an exhaust pipe that guides exhaust gas exhausted from the engine to the outside, a catalyst housed in the exhaust pipe section, and an additive that is located upstream of the catalyst and supplies an additive to the catalyst The additive injection valve is provided with an additive injection valve 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. A radiator that covers the wall of the injection passage without interfering with the injected additive, can generate heat when energized, and can resonate with engine vibration generated by engine operation; And a current-carrying circuit that energizes the radiator and heats the radiator. In other words, the technology that burns out the additive and the technology that makes it difficult to attach soot by vibration were adopted .

According to the first 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 vibrator. Therefore, it is possible to prevent the additive from accumulating in the injection passage.
According to the second aspect of the present invention, the additive is prevented more effectively from being deposited in the injection passage by combining the technique for burning the additive and the technique for making it difficult to adhere soot by vibration. be able to.

Hereinafter, the technology that is the basis of the present invention will be described with reference to FIGS. 1 and 2.
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.

Also the injection passage 26a is that soot suppression unit 3 0 restrain the soot contained in the exhaust gas adheres to the wall surface of the injection passage 26a is provided. For example, soot suppressing portion 30, the heat radiator 32 placed in the injection duct 28, by the heat is radiated from the discharge Netsutai 32, the structure to dry soot 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 recess 26, and the outer peripheral surface of the heat radiating body 32 is the side face of the recess 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.

The supply heat to the heat dissipating member 32, for example, heat supply structure of the exhaust gas of a diesel engine is used. 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 receiving heat portion 37 a flange portion 32a, the heat of the exhaust gas flowing through the bent portion 15a, transmitted to the heat discharging body 32, so that heat is radiated from each part of the radiator 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 operation will be described. During operation of the diesel engine, exhaust gas exhausted from the diesel engine is passed 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 dissipating body 32 has a shape that covers the inner surface of the recess 26, that is, a shape that surrounds 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 reference embodiment of the present invention.
The embodiment does not use a structure that takes in the heat of the exhaust gas from the flange (heat receiving portion), but causes the radiator 32 itself to function as an electric heater so that the heat is radiated (heated) from the radiator 32. It is a thing.

Specifically, the energizing circuit 40 to the outside of the exhaust pipe as shown in provided 3, by connecting this energizing circuit 40 and the heat radiator 32, the power supplied from the current supply circuit 40, a heat radiator 32 It functions as an electric heater so that heat is radiated from each part of the radiator 32.
In this way, when Ru dried soot P attached with the fuel vapor, is suppressed adhesion in each part of the injection passage 26a of soot P, it is possible to prevent the deposition of the soot P. In this case, the temperature of the radiator may be further increased to burn the soot P itself. Of course, it may be used in combination structure incorporating heat of the exhaust gas from the flange 37 (the heat receiving portion) as shown in two-dot chain line in FIG. 3.

However, in FIG. 3, the same reference numerals are given to the same parts as those of the technical form that forms the basis of the invention, and the description thereof is omitted.
4 and 5 show a first embodiment of the present invention.
The present embodiment does not use a structure in which the adhesion of the soot P is thermally eliminated, but uses a structure in which the adhesion of the soot P is eliminated by vibration.

That is, soot suppressing portion 30 of the present embodiment, instead of the heat radiating body, the vibrating body 45 using with the substantially same outer as used in the form of technology for example underlying the invention, using a resonance structure 50 Thus, a structure that applies 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 , 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 .

However, in FIG. 4 and FIG. 5, the same reference numerals are given to the same parts as the forms that form the basis of the invention, and the description thereof is omitted.
FIG. 6 shows a second embodiment of the present invention.
In the present embodiment, a structure in which the technology for drying the soot P to make it difficult to attach the soot P and the technology for making it difficult to attach the soot P by vibration is used as the soot adhesion suppressing unit.

  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 is not only resonated by 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 brought about 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 first 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.

  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, in the above embodiment it has been described using the soot as deposits on the injection duct, a substance contained in the exhaust gas or additives may apply as long as it is deposited as a solid.

The side view which carried out the partial cross section of the exhaust-gas purification apparatus explaining the technique used as the foundation of this invention. The sectional side view which expands and shows the part in which the fuel addition valve of the same apparatus was installed. The side sectional view showing the important section of the exhaust gas purification device concerning the embodiment which serves as a reference of the present invention. 1 is a side sectional view showing a main part of an exhaust gas purification apparatus according to a first embodiment of the present 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 2nd 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 )
3 2 Radiator 32a Flange (heat receiving part)
37 Heat receiving part (heat source part)
40 energizing circuit 45 vibrator 50 resonant structure P soot

Claims (2)

An exhaust pipe for guiding exhaust gas exhausted from the engine to the outside;
A catalyst housed in the exhaust pipe section;
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;
Vibration that resonates with engine vibration generated by operation of the engine, which is 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. exhaust gas purification system of an internal combustion engine, characterized by comprising a body. An exhaust pipe for guiding exhaust gas exhausted from the engine to the outside;
A catalyst housed in the exhaust pipe section;
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;
In the injection passage, disposed so as to cover the wall surface of the injection passage without interfering with the additive injected from the additive injection valve, can generate heat by energization, and is generated by the operation of the engine. A radiator that can resonate with engine vibrations,
An exhaust gas purification apparatus for an internal combustion engine, comprising an energization circuit provided outside the exhaust pipe and energizing the heat dissipating body to generate heat .

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