JP5626100B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

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

  As an exhaust emission control device for an internal combustion engine, an oxidation catalyst is arranged in the exhaust passage, and a small oxidation catalyst and a fuel supply valve for adding fuel to the small oxidation catalyst are further arranged upstream of the oxidation catalyst. A device that effectively uses the temperature raising function and the reforming function of a small oxidation catalyst by controlling the supply amount is known (see, for example, Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP 2009-156168 A JP 2004-197635 A JP 2010-180863 A

  If the tip of the fuel supply valve is exposed to high-temperature exhaust, the nozzle hole of the fuel supply valve may be clogged with deposits. The contact with is suppressed. However, if it becomes difficult for the exhaust gas to flow in, deposits may accumulate on the installation portion of the fuel supply valve.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an internal combustion engine exhaust gas purification device that prevents clogging of a nozzle hole of a fuel supply valve and suppresses the accumulation of deposits on the installation portion of the fuel supply valve.

An exhaust purification device for an internal combustion engine according to the present invention supplies an exhaust purification catalyst disposed in an exhaust passage of the internal combustion engine and a reducing agent to the exhaust purification catalyst from the upstream side in the exhaust flow direction with respect to the exhaust purification catalyst. An exhaust purification device for an internal combustion engine comprising a reducing agent supply device, wherein the exhaust pipe forming the exhaust passage is provided with a supply valve of the reducing agent supply device, and the exhaust pipe having a cylindrical shape of the exhaust pipe An installation portion that is retracted with respect to the surface is provided, and the installation portion has a first projection that projects upstream of exhaust flowing in the exhaust pipe in a circumferential direction with respect to the supply valve, and the supply at the downstream side thereof. And a first inclined portion inclined from the valve toward the exhaust pipe surface so as to follow the flow of exhaust gas (Claim 1).

  According to the exhaust emission control device of the present invention, the exhaust gas flowing in the circumferential direction of the exhaust pipe is guided to the first inclined portion by the first projecting portion without directly hitting the supply valve. Exhaust gas hitting the first inclined portion is guided along the slope of the first inclined portion and merges with the main flow of the exhaust pipe. Since the exhaust flow in the exhaust pipe does not directly hit the supply valve, the nozzle hole of the supply valve is prevented from being clogged. Since the exhaust flow hits the first inclined portion and merges with the main flow of the exhaust pipe, the occurrence of stagnation points near the first inclined portion is prevented, and deposit accumulation is prevented. Therefore, it is possible to prevent clogging of the nozzle hole of the supply valve and accumulation of deposits in the installation portion.

  In one form of the exhaust emission control device of the present invention, the supply valve may be installed in the installation part so that the reducing agent supplied from the supply valve hits the first inclined part (Claim 2). According to this aspect, the reducing agent is sprayed by the supply valve on the exhaust gas guided by the first protrusion, and the exhaust gas containing the reducing agent hits the first inclined portion. Since the deposit of the reducing agent deposited on the first inclined portion flows, the deposition of the deposit can be prevented.

  In one form of the exhaust emission control device of the present invention, the reducing agent supply device may be provided on the downstream side in the exhaust flow direction with respect to the supercharger of the internal combustion engine. According to this aspect, it is possible to prevent the clogging of the nozzle hole of the supply valve and the accumulation of deposits in the installation portion against the circumferential flow of the exhaust pipe generated by the supercharger.

  In one form of the exhaust emission control device of the present invention, the installation portion includes a second projecting portion projecting on the upstream side of the exhaust gas flowing in the axial direction in the exhaust pipe with respect to the supply valve, and the supply valve on the downstream side thereof. And a second inclined portion inclined so as to follow the flow of the exhaust toward the exhaust pipe surface (Claim 4). According to this aspect, in addition to the flow in the circumferential direction of the exhaust pipe, it is possible to prevent the clogging of the nozzle hole of the supply valve and the accumulation of deposits in the installation portion due to the exhaust flowing in the axial direction of the exhaust pipe.

  As described above, in the present invention, the flow of exhaust gas in the exhaust pipe does not directly hit the supply valve, so that the nozzle hole of the supply valve is prevented from being clogged. Since the exhaust flow hits the first inclined portion and merges with the main flow of the exhaust pipe, the occurrence of stagnation points near the first inclined portion is prevented, and deposit accumulation is prevented. Therefore, it is possible to prevent clogging of the nozzle hole of the supply valve and accumulation of deposits in the installation portion.

1 is a schematic diagram of an exhaust gas purification apparatus for an internal combustion engine according to one embodiment of the present invention. Sectional drawing cut | disconnected along the II-II line | wire of FIG. The figure which shows the simulation model of an exhaust gas purification apparatus. The figure which shows the simulation result of the direction through which exhaust flows in the sectional drawing cut | disconnected along the IV-IV line | wire of FIG. The figure which shows the simulation result of the flow velocity of exhaust_gas | exhaustion in sectional drawing cut | disconnected in the axial direction of the exhaust pipe.

  FIG. 1 is a schematic view of an exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present invention. FIG. 1 is a cross-sectional view taken along the exhaust flow direction F. FIG. The exhaust purification device 1 is configured as a part of an exhaust system of an internal combustion engine, and is provided in an exhaust passage 2 on the downstream side in the exhaust flow direction F with respect to a turbocharger as a supercharger of an internal combustion engine (not shown). The exhaust purification device 1 supplies an exhaust purification catalyst 4 installed in an exhaust pipe 3 constituting the exhaust passage 2 and a reducing agent to the exhaust purification catalyst 4 from the upstream side in the exhaust flow direction F with respect to the exhaust purification catalyst 4. And a reducing agent supply device 5. In the exhaust pipe 3, an installation portion 6 that is retracted with respect to the cylindrical exhaust pipe surface 3 a is provided, and a supply valve 5 a of the reducing agent supply device 5 is installed. The exhaust flow direction F is along the axial direction of the exhaust pipe 3.

  The exhaust purification catalyst 4 is an oxidation catalyst. As an example, a substrate having a laminated structure of a thin metal flat plate and a thin metal corrugated plate is formed, and a layer of a catalyst carrier made of alumina, for example, is formed on the surface of the substrate, and platinum Pt, rhodium Rd is formed on the catalyst carrier. A catalyst on which a noble metal catalyst such as palladium Pd is supported is used. The reducing agent supply device 5 supplies fuel as a reducing agent to the exhaust purification catalyst 4. The supply valve 5 a of the reducing agent supply device 5 injects part of the fuel guided from a fuel tank (not shown) toward the exhaust purification catalyst 4. If the exhaust purification catalyst 4 is activated, the temperature of the exhaust purification catalyst 4 is raised by the oxidation reaction heat generated when the fuel is oxidized in the exhaust purification catalyst 4.

  The installation portion 6 has a shape that is recessed with respect to the exhaust pipe surface 3a. FIG. 2 is a cross-sectional view taken along line II-II in FIG. In the exhaust passage 2, a swirling flow C is generated in the circumferential direction in the exhaust pipe 3 by a turbocharger provided upstream in the flow direction F of the exhaust purification device 1. In the installation part 6, the 1st protrusion part 7 is provided in the flow direction upstream of this turning flow C with respect to the supply valve 5a. A slope 7a is formed along the flow of the swirling flow C between the vicinity of the apex of the first protrusion 7 and the exhaust pipe surface 3a. Further, the installation portion 6 on the downstream side in the flow direction of the swirling flow C with respect to the supply valve 5a has a first inclined portion 8 inclined so as to follow the flow of exhaust from the vicinity of the supply valve 5a toward the exhaust pipe surface 3a. Is provided. The first inclined portion 8 has a gentle slope 8a so as to follow the flow of the swirling flow C. The first inclined portion 8 is provided so that the angle α formed by the flow direction of the swirling flow C and the inclined surface 8a becomes an acute angle.

  Returning to FIG. 1, the second projecting portion 9 is provided on the upstream side in the exhaust flow direction F with respect to the supply valve 5 a in the installation portion 6. A slope 9a along the exhaust flow direction F is formed between the vicinity of the apex of the second protrusion 9 and the exhaust pipe surface 3a. In addition, a second inclined portion 10 that is inclined so as to follow the flow of exhaust gas from the vicinity of the supply valve 5a toward the exhaust pipe surface 3a is provided in the installation portion 6 on the downstream side in the flow direction F with respect to the supply valve 5a. Yes. The second inclined portion 10 has a gentle inclined surface 10a along the flow direction F of the exhaust gas.

  Next, the operation of the exhaust emission control device 1 will be described. First, with reference to FIG. 2, the effect | action of the installation part 6 with respect to the swirling flow C which flows through the circumferential direction of the exhaust pipe 3 is demonstrated. In the installation portion 6, on the upstream side in the flow direction of the swirling flow C of the exhaust gas flowing from the turbocharger with respect to the supply valve 5a, the exhaust does not flow to the vicinity of the supply valve 5a by the first protrusion 7. Since the swirling flow C flows along the inclined surface 7a formed between the vicinity of the apex of the first protrusion 7 and the exhaust pipe surface 3a, the swirling flow C flows to the supply valve 5a provided at a position retreated with respect to the exhaust flow direction. Does not hit the exhaust directly, but hits the slope 8a of the first inclined portion 8. The exhaust gas hitting the inclined surface 8a includes fuel, and the first inclined portion 8 hits the fuel. Deposits deposited on the slope 8a are flowed by this fuel to prevent clogging of the spray path. Therefore, the spray path clogging in the installation part 6 is also prevented while preventing the injection hole clogging caused by the hot exhaust gas hitting the supply valve 5a. Further, since the inclined surface 8a and the direction of the swirling flow C are configured to have an acute angle, deposits deposited on the first inclined portion 8 can be prevented even by the shearing force of the swirling flow C. The angle formed by the slope 8a and the direction of the swirling flow C is preferably as small as possible, and is preferably 45 ° or less.

  Next, the operation of the installation portion 6 for the exhaust gas flowing in the axial direction of the exhaust pipe 3 will be described with reference to FIG. In the installation portion 6, the exhaust flows so as not to directly apply the exhaust to the supply valve 5 a by the second protrusion 9 provided on the upstream side in the exhaust flow direction F with respect to the supply valve 5 a. At the same time, the exhaust gas flows along the slope 9a between the vicinity of the apex of the second protrusion 9 and the exhaust pipe surface 3a, so that the exhaust gas can be guided to the vicinity of the supply valve 5a. Exhaust gas from the inclined surface 9a hits the second inclined portion 10 and is guided along the inclined surface 10a of the second inclined portion 10 to flow to the exhaust pipe surface 3a. As a result, exhaust stagnation points do not occur in the vicinity of the installation surface 6, and deposit accumulation on the second inclined portion 10 can be prevented.

  For comparison, the installation portion 11 having a conventional shape is shown by a broken line in FIGS. In FIG. 2, in the conventional-shaped installation part 11, the swirling flow C easily flows into the fuel spray path supplied by the supply valve 5 a in the installation part 11, and the flow rate of exhaust gas decreases in the installation part 11 and the supply valve Exhaust gas flowed to the vicinity of 5a, and there was a possibility of causing nozzle hole clogging and spray path clogging. Also in FIG. 1, if the exhaust gas easily flows into the installation portion 6 and hits the supply valve 5a, there is a possibility that the injection hole is clogged. In the present invention, attention is paid to two flows that can be distinguished from the flow direction F of the exhaust gas flowing in the axial direction of the exhaust pipe 3 and the swirling flow C flowing in the circumferential direction of the exhaust pipe 3. The exhaust is prevented from directly hitting the supply valve 5a on the upstream side in the flow direction with respect to the supply valve 5a in each flow, and the exhaust flow hits the inclined surfaces 8a and 10a of the inclined portions 8 and 10 on the downstream side in the flow direction. The exhaust flows along 10a. Since the downstream exhaust contains the fuel supplied from the supply valve 5a, the deposits adhering to the inclined portions 8 and 10 are washed away by the fuel, and deposits can be prevented. Deposits can also be prevented from being deposited by removing shearing force caused by the swirl flow C in the first inclined portion 8 and eliminating the stagnation point caused by the inclined surface 10a in the second inclined portion 10. In this way, by paying attention to the flow of exhaust gas, it is possible to prevent deposit accumulation in the installation portion 6 and clogging of the injection valve of the supply valve 5a in each flow.

  The simulation result of the flow direction of the exhaust gas near the installation portion 6 will be described below. FIG. 3 shows a simulation model of the exhaust emission control device 1, and is a cross-sectional view cut in the exhaust flow direction F. About each member, description is abbreviate | omitted by giving the same referential mark as the description mentioned above. In FIG. 3, the direction of the exhaust gas flow direction F is different from that illustrated in FIGS. 1 and 2. FIG. 4 shows a cross-sectional view taken along line IV-IV in FIG. In FIG. 4, the simulation results in the direction in which the exhaust flows are indicated by arrows. Due to the first protrusion 7 and its inclined surface 7a, the flow of the exhaust gas by the swirling flow C moves along the inclined surface 7a, and hits the opposing first inclined portion 8 and moves along the inclined surface 8a. The angle β formed by the flow direction of the exhaust gas guided by the inclined surface 7a forming the first protrusion 7 and the inclined surface 8a of the first inclined portion 8 contacts with an acute angle of 45 ° as an example.

  FIG. 5 is a diagram showing a simulation result of the flow velocity of the exhaust gas in a cross-sectional view cut in the flow direction F of the exhaust gas. FIG. 5 is a distribution diagram in which the flow velocity is distinguished for each speed. Since the exhaust gas guided along the slope 9a of the second protrusion 9 flows in the direction along the slope 9a, it does not flow into the innermost part 6a where the supply valve 5a is installed. The flow velocity in the vicinity of the innermost portion 6a is small, and it can be said from the simulation results that the exhaust gas hardly flows into the vicinity of the innermost portion 6a. On the other hand, the exhaust gas guided along the inclined surface 9 a hits the second inclined portion 10, flows along the inclined surface 10 a, and joins the main flow in the exhaust pipe 3. In the vicinity of the second inclined portion 10, the inclined surface 10a is smoothly connected to the exhaust pipe surface 3a, and the exhaust gas flows while maintaining a certain speed, so that no stagnation point is generated. Accordingly, deposit accumulation can be suppressed and spray path clogging can be prevented.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, in the present embodiment, the exhaust purification device has been described using a combination of an oxidation catalyst and fuel, but is not limited thereto. For example, various known exhaust purification methods such as a reducing agent such as urea and a selective reduction type NOx catalyst (SCR) may be applied. Further, in the present embodiment, the exhaust gas purification device 1 provided on the downstream side in the exhaust flow direction with respect to the turbocharger has been described. However, the present invention is not limited to this. The present invention can be applied to the case where the exhaust gas purification device is provided in a place where the swirling flow C is generated in addition to the main flow direction F. In this embodiment, focusing on two flows in the swirling flow C and the exhaust flow direction F, the first protrusion 7, the first inclined portion 8, the second protruding portion 9, and the second inclined portion 10 are described. However, it is not limited to this. The form which provided only any one of the 1st projection part 7 and the 1st inclination part 8, or the 2nd projection part 9 and the 2nd inclination part 10 may be sufficient. In particular, the configuration may be such that only the first protrusion 7 and the first inclined portion 8 are provided, whereby the nozzle hole clogging and spray path clogging due to the swirling flow C can be prevented.

DESCRIPTION OF SYMBOLS 1 Exhaust purification device 3 Exhaust pipe 3a Exhaust pipe surface 4 Exhaust purification catalyst 5 Reducing agent supply apparatus 5a Supply valve 6 Installation part 7 1st projection part 8 1st inclination part

Claims (4)

An internal combustion engine comprising: an exhaust purification catalyst disposed in an exhaust passage of the internal combustion engine; and a reducing agent supply device that supplies a reducing agent to the exhaust purification catalyst from an upstream side in an exhaust flow direction with respect to the exhaust purification catalyst In the exhaust purification device of
The exhaust pipe that forms the exhaust passage is provided with an installation portion that is provided with a supply valve of the reducing agent supply device and that is retreated with respect to the cylindrical exhaust pipe surface of the exhaust pipe. A first projecting portion projecting on the upstream side of the exhaust gas flowing in the circumferential direction in the exhaust pipe with respect to the supply valve, and inclined downstream from the supply valve toward the exhaust pipe surface along the flow of the exhaust gas An exhaust purification device for an internal combustion engine provided with the first inclined portion.   2. The exhaust emission control device according to claim 1, wherein the supply valve is installed in the installation portion so that the reducing agent supplied from the supply valve hits the first inclined portion.   The exhaust emission control device according to claim 1 or 2, wherein the reducing agent supply device is provided on the downstream side in the exhaust flow direction with respect to the supercharger of the internal combustion engine.   The installation portion includes a second projecting portion projecting on the upstream side of the exhaust gas flowing in the axial direction in the exhaust pipe with respect to the supply valve, and an exhaust flow from the supply valve toward the exhaust pipe surface on the downstream side. The exhaust emission control device according to any one of claims 1 to 3, further comprising a second inclined portion that is inclined so as to extend along the line.

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