JP7647523B2 - Exhaust purification equipment - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. Publication date: June 20, 2021. Publication location: Toyota Auto Body Co., Ltd., Yoshiwara Plant (25 Kamifujiike, Yoshiwara-cho, Toyota City, Aichi Prefecture)

The present invention relates to an exhaust purification device.

As a conventional exhaust purification device, for example, the technology described in Patent Document 1 is known. The exhaust purification device described in Patent Document 1 includes an expansion chamber connected to an exhaust pipe through which exhaust gas from an internal combustion engine flows, an exhaust catalyst connected to this expansion chamber via the exhaust pipe, and an addition valve that supplies reducing agent to the exhaust gas flowing in the exhaust pipe. Inside the expansion chamber, a backstep flow and a swirling flow of the exhaust gas are generated to promote homogeneous mixing of the exhaust gas and reducing agent and eliminate uneven flow rates.

JP 2009-47091 A

In recent years, for various reasons, it is desirable to shorten the distance of the exhaust passage from the exhaust manifold of the internal combustion engine to the exhaust catalyst in vehicles. For this reason, there is a trend to mount the exhaust catalyst and additive valve near the internal combustion engine. However, in the above-mentioned conventional technology, an expansion chamber is mounted to mix the reducing agent (additive) supplied into the exhaust pipe by the additive valve evenly with the exhaust gas. Therefore, the exhaust passage from the internal combustion engine to the exhaust catalyst is inevitably long.

The object of the present invention is to provide an exhaust purification device that can uniformly mix additives into exhaust gas while shortening the distance of the exhaust passage from the internal combustion engine to the exhaust catalyst.

In one aspect of the present invention, an exhaust purification device that purifies exhaust gas flowing through an exhaust passage connected to an internal combustion engine includes an exhaust catalyst disposed in the exhaust passage and removing harmful substances contained in the exhaust gas, an additive valve that injects an additive upstream of the exhaust catalyst in an exhaust pipe that forms the exhaust passage, and an additive dispersion plate that is disposed upstream of the exhaust catalyst in the exhaust pipe and disperses the additive injected from the additive valve, the additive dispersion plate having a bottom wall portion having a wall surface against which the additive injected from the additive valve hits, and a side wall portion connected to the edge of the bottom wall portion, and a notch portion is provided in an area of the side wall portion including a position where the additive that hits the wall surface is reflected.

In such an exhaust purification device, by arranging an additive dispersion plate upstream of the exhaust catalyst in the exhaust pipe, the additive injected from the additive valve hits the wall surface of the bottom wall and flows downstream together with the exhaust gas. Therefore, compared to when an additive dispersion plate is not arranged in the exhaust pipe, the distance the additive flows to the exhaust catalyst is longer, which promotes evaporation of the additive and makes it easier for the additive to mix with the exhaust gas. In addition, by providing a notch in the additive dispersion plate in an area including the position where the additive that hits the wall surface of the bottom wall of the side wall is reflected, a part of the additive injected from the additive valve passes through the notch and is mixed with the exhaust gas. Therefore, the additive is more easily mixed with the exhaust gas. As a result, the additive can be mixed uniformly with the exhaust gas while shortening the distance of the exhaust passage from the internal combustion engine to the exhaust catalyst.

The cutout may extend to the downstream end of the side wall. In this configuration, the cutout can be easily processed and the additive dispersion plate can be easily manufactured, while allowing the additive to be mixed uniformly into the exhaust gas.

The additive dispersion plate divides a part of the exhaust pipe into a first space located on the additive valve side and a second space located on the opposite side of the additive valve, and the additive dispersion plate has an inlet at the upstream end through which the exhaust gas flows into the first space, and an outlet at the downstream end through which the additive injected from the additive valve flows out of the first space together with the exhaust gas, and the opening area of the inlet may be smaller than the opening area of the outlet. In this configuration, the flow of exhaust gas from the upstream side of the additive dispersion plate into the first space is restricted, so that the additive injected from the additive valve is more likely to hit the wall surface of the bottom wall. In addition, the swirling flow of the exhaust gas flowing through the second space on the downstream side of the additive dispersion plate is suppressed, and the flow of exhaust gas toward the exhaust catalyst is rectified.

The additive valve is disposed at the top of the exhaust pipe, and the additive dispersion plate may be disposed so as to incline downward from the upstream side to the downstream side of the exhaust pipe. In such a configuration, the additive injected from the additive valve hits the wall surface of the bottom wall portion and tends to flow downstream. This makes it easier for the additive to mix with the exhaust gas, so that the additive can be mixed more uniformly into the exhaust gas.

The present invention makes it possible to uniformly mix additives into the exhaust gas while shortening the distance of the exhaust passage from the internal combustion engine to the exhaust catalyst.

1 is a schematic configuration diagram showing an engine system equipped with an exhaust purification device according to an embodiment of the present invention. 2 is a schematic cross-sectional view showing the inside of a bent portion of the exhaust pipe shown in FIG. 1 . FIG. 2 is a plan view of a bent portion of the exhaust pipe shown in FIG. 1 . FIG. 2 is a front view of the bent portion of the exhaust pipe shown in FIG. 1 . 5 is a cross-sectional view taken along line V-V in FIG. 4. 6 is a cross-sectional view taken along line VI-VI of FIG.

The following describes an embodiment of the present invention in detail with reference to the drawings.

Figure 1 is a schematic diagram showing an engine system equipped with an exhaust purification device according to one embodiment of the present invention. In Figure 1, the engine system 1 is mounted on a vehicle 2 such as an automobile. The engine system 1 includes an internal combustion engine 3, an intake pipe 4, and an exhaust pipe 5. The engine 3 is, for example, a four-cylinder diesel engine.

The intake pipe 4 is connected to the engine 3 via an intake manifold 6. The intake pipe 4 forms an intake passage 7 through which air (intake air) supplied to the engine 3 flows. The exhaust pipe 5 is connected to the engine 3 via an exhaust manifold 8. The exhaust pipe 5 forms an exhaust passage 9 through which exhaust gas generated within the engine 3 flows.

The turbine 11 of the turbocharger 10 is disposed in the exhaust passage 9. The compressor 12 of the turbocharger 10 is disposed in the intake passage 7. The turbine 11 is driven to rotate by the exhaust gas. The compressor 12 is driven to rotate by the turbine 11, compresses the air flowing through the intake passage 7, and sends it to the engine 3. Although not specifically shown, the turbocharger 10 is, for example, a twin turbo (see FIG. 2).

The engine system 1 also includes an exhaust purification device 13 according to this embodiment. The exhaust purification device 13 purifies the exhaust gas flowing through the exhaust passage 9. The exhaust purification device 13 includes a DOC 14 (Diesel Oxidation Catalyst) and a DPF 15 (Diesel Particulate Filter) arranged in order from the upstream side to the downstream side in the exhaust passage 9.

The DOC 14 oxidizes and purifies carbon monoxide (CO) and hydrocarbons (HC) contained in the exhaust gas. The DPF 15 collects particulate matter (PM) contained in the exhaust gas. The DOC 14 and DPF 15 are exhaust catalysts that remove harmful substances contained in the exhaust gas.

A crank-shaped bend 17 is provided between the turbine 11 and the DOC 14 in the exhaust pipe 5. The exhaust pipe 5 is made up of multiple pipes connected together.

The exhaust purification device 13 also includes a fuel addition valve 20 attached to the bent portion 17. The fuel addition valve 20 is an addition valve that injects liquid fuel, which is an additive for raising the temperature of the exhaust gas, toward the DOC 14 when regenerating the DPF 15. Regeneration of the DPF 15 means burning the PM that has accumulated in the DPF 15.

Figure 2 is a schematic cross-sectional view showing the inside of the bent portion 17 of the exhaust pipe 5. Figure 3 is a plan view of the bent portion 17 of the exhaust pipe 5. Figure 4 is a front view of the bent portion 17 of the exhaust pipe 5. Figure 5 is a cross-sectional view taken along line V-V in Figure 4. Figure 6 is a cross-sectional view taken along line VI-VI in Figure 3.

In Figures 1 to 6, the exhaust purification device 13 includes a fuel distribution plate 22 disposed inside the bent portion 17 of the exhaust pipe 5. The fuel distribution plate 22 is disposed upstream of the DOC 14 in the exhaust pipe 5. The fuel distribution plate 22 is an additive distribution plate that disperses liquid fuel, which is an additive injected from the fuel addition valve 20. The fuel distribution plate 22 is integrally formed with the exhaust pipe 5, for example, by casting. The fuel addition valve 20 is disposed at the upper part of the upstream side of the bent portion 17 of the exhaust pipe 5.

The fuel distribution plate 22 has a generally U-shaped cross section. The fuel distribution plate 22 has a bottom wall portion 23 having a wall surface 23a against which the fuel injected from the fuel addition valve 20 strikes, and side wall portions 24, 25 connected to both side edges of the bottom wall portion 23. When the fuel injected from the fuel addition valve 20 strikes the wall surface 23a, the fuel spray is scattered and atomized, promoting the dispersion of the fuel.

A notch 26 is provided in an area of the side wall 25 that includes a position where fuel that hits the wall surface 23a is reflected. The notch 26 is provided so as to extend to the downstream end of the side wall 25. The shape and dimensions of the notch 26 are not particularly limited and are set appropriately depending on the structure of the exhaust pipe 5, etc.

The fuel dispersion plate 22 is also arranged so that it is inclined downward (opposite the fuel addition valve 20) from the upstream side to the downstream side of the exhaust pipe 5. This prevents the fuel that has been atomized by hitting the wall surface 23a of the bottom wall portion 23 from remaining on the wall surface 23a and turning into droplets, further promoting the dispersion of the fuel.

A portion of the fuel injected from the fuel addition valve 20 hits the wall surface 23a of the bottom wall 23 and is reflected downstream, or flows downstream while adhering to the wall surface 23a of the bottom wall 23. The remaining fuel injected from the fuel addition valve 20 hits the wall surface 23a of the bottom wall 23 and is reflected toward the side wall 25, and flows through the notch 26.

The fuel distribution plate 22 divides a portion of the exhaust pipe 5 into a first space 27 located on the fuel addition valve 20 side and a second space 28 located on the opposite side of the fuel addition valve 20. The fuel distribution plate 22 is disposed on the fuel addition valve 20 side of the axis G of the exhaust pipe 5 within the exhaust pipe 5. The first space 27 is narrower than the second space 28. Fuel injected from the fuel addition valve 20 flows together with exhaust gas in the first space 27. Mainly exhaust gas flows in the second space 28.

The upstream end of the fuel distribution plate 22 is provided with an inlet 30 through which exhaust gas flows in. The downstream end of the fuel distribution plate 22 is provided with an outlet 31 through which fuel injected from the fuel addition valve 20 flows out together with the exhaust gas. The opening area of the inlet 30 is smaller than the opening area of the outlet 31. Because the opening area of the inlet 30 is narrowed in this way, the inflow of exhaust gas into the first space 27 is suppressed. Therefore, the fuel injected from the fuel addition valve 20 is less likely to be hindered from hitting the wall surface 23a of the bottom wall portion 23, further promoting the dispersion of the fuel.

In the exhaust purification device 13 described above, when the exhaust gas from the engine 3 reaches the fuel distribution plate 22, most of the exhaust gas flows through the second space 28 toward the DOC 14. The remaining exhaust gas is introduced into the first space 27 from the inlet 30 of the fuel distribution plate 22.

Fuel injected from the fuel addition valve 20 hits the wall surface 23a of the bottom wall portion 23 of the fuel distribution plate 22 and is atomized. A part of the atomized fuel is mixed with the exhaust gas introduced into the first space 27 and flows downstream, and is discharged from the outlet 31 of the fuel distribution plate 22. The fuel that flows out from the outlet 31 of the fuel distribution plate 22 is mixed with the exhaust gas that has flowed through the second space 28. The remaining fuel flows out of the fuel distribution plate 22 through the notch 26 provided in the side wall portion 25 of the fuel distribution plate 22 and is mixed with the exhaust gas flowing through the second space 28.

However, if the fuel dispersion plate 22 is not disposed in the exhaust pipe 5, the distance that the fuel injected from the fuel addition valve 20 must travel to reach the DOC 14 is shortened. This reduces the volatility of the fuel and makes it difficult for the fuel to be atomized, making it difficult to mix the fuel evenly into the exhaust gas.

In response to such a problem, in this embodiment, the fuel dispersion plate 22 is disposed upstream of the DOC 14 in the exhaust pipe 5, so that the fuel injected from the fuel addition valve 20 hits the wall surface 23a of the bottom wall portion 23 and flows downstream together with the exhaust gas. Therefore, compared to when the fuel dispersion plate 22 is not disposed in the exhaust pipe 5, the distance that the fuel flows to the DOC 14 is longer, so that the fuel evaporation is promoted and the fuel is more easily mixed with the exhaust gas. In addition, by providing a notch 26 in the fuel dispersion plate 22 in an area including the position where the fuel that hits the wall surface 23a of the bottom wall portion 23 in the side wall portion 25 is reflected, a part of the fuel injected from the fuel addition valve 20 passes through the notch 26 and is mixed with the exhaust gas. Therefore, the fuel is more easily mixed with the exhaust gas. As a result, the distance of the exhaust passage 9 from the engine 3 to the DOC 14 can be shortened while the fuel is evenly mixed with the exhaust gas.

As a result, by placing the DOC 14 close to the engine 3, the DOC 14 can be warmed up quickly. In addition, it is possible to achieve both uniformity of fuel distribution in the DOC 14 and resistance to fuel-related deposits.

In addition, in this embodiment, the cutout portion 26 is provided so as to extend to the downstream end of the side wall portion 25. This makes it easy to process the cutout portion 26 and manufacture the fuel dispersion plate 22, while allowing the fuel to be mixed uniformly with the exhaust gas.

In addition, in this embodiment, the fuel distribution plate 22 divides a portion of the exhaust pipe 5 into a first space 27 located on the fuel addition valve 20 side and a second space 28 located on the opposite side of the fuel addition valve 20, and the opening area of the inlet 30 provided at the upstream end of the fuel distribution plate 22 is smaller than the opening area of the outlet 31 provided at the downstream end of the fuel distribution plate 22. Therefore, the flow of exhaust gas from the upstream side of the fuel distribution plate 22 into the first space 27 is restricted, so that the fuel injected from the fuel addition valve 20 is more likely to hit the wall surface 23a of the bottom wall portion 23. In addition, the swirling flow of exhaust gas flowing through the second space 28 on the downstream side of the fuel distribution plate 22 is suppressed, and the flow of exhaust gas toward the DOC 14 is rectified.

In addition, in this embodiment, the fuel addition valve 20 is disposed at the top of the exhaust pipe 5, and the fuel distribution plate 22 is disposed so as to incline downward from the upstream side to the downstream side of the exhaust pipe 5. This makes it easier for the fuel injected from the fuel addition valve 20 to hit the wall surface 23a of the bottom wall portion 23 and flow downstream. This makes it easier for the fuel to mix with the exhaust gas, so that the fuel can be mixed more uniformly with the exhaust gas.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the notch 26 is provided in the fuel distribution plate 22 so as to extend to the downstream end of the side wall portion 25, but the present invention is not particularly limited to such a form. For example, the notch 26 may be provided only at a position in the side wall portion 25 where the fuel that hits the wall surface 23a of the bottom wall portion 23 is reflected.

In addition, in the above embodiment, the notch is provided only in the side wall portion 25 of the fuel distribution plate 22, but this is not limited to this form, and depending on the internal structure of the exhaust pipe 5, etc., the notch may be provided in both the side wall portions 24, 25 of the fuel distribution plate 22.

In addition, in the above embodiment, the fuel distribution plate 22 has a generally U-shaped cross section, but the shape of the fuel distribution plate 22 is not particularly limited to this form, and may have a curved cross section, for example. In this case, for example, the portion having the wall surface against which the fuel injected from the fuel addition valve 20 hits may be configured as the bottom wall portion, and the portions on both the left and right sides of the bottom wall portion may be configured as side wall portions.

In addition, in the above embodiment, the opening area of the inlet 30 is smaller than the opening area of the outlet 31 in the first space 27 in the exhaust pipe 5, but this is not particularly limited to this form, and the opening area of the inlet 30 may be equal to the opening area of the outlet 31.

In addition, in the above embodiment, a fuel dispersion plate 22 that disperses the fuel injected from the fuel addition valve 20 is disposed upstream of the DOC 14 in the exhaust pipe 5, but the present invention can be applied to devices other than the fuel addition valve 20.

For example, if a selective catalytic reduction (SCR) catalyst that uses urea water to reduce and purify nitrogen oxides (NOx) contained in the exhaust gas is disposed downstream of the DPF 15 in the exhaust passage 9, the present invention may be applied to a urea water dispersion plate that disperses the urea water injected from the urea water addition valve.

3...engine (internal combustion engine), 5...exhaust pipe, 9...exhaust passage, 13...exhaust purification device, 14...DOC (exhaust catalyst), 20...fuel addition valve (additive valve), 22...fuel distribution plate (additive distribution plate), 23...bottom wall portion, 23a...wall surface, 24, 25...side wall portions, 26...notch portion, 27...first space, 28...second space, 30...inlet, 31...outlet.

Claims (4)

An exhaust gas purification device that purifies exhaust gas flowing through an exhaust passage connected to an internal combustion engine,
an exhaust catalyst disposed in the exhaust passage for removing harmful substances contained in the exhaust gas;
an additive valve that injects an additive into an exhaust pipe that forms the exhaust passage, upstream of the exhaust catalyst;
an additive dispersion plate that is disposed upstream of the exhaust catalyst in the exhaust pipe and disperses the additive injected from the additive valve,
the additive dispersion plate is disposed between a turbine that is disposed in the exhaust passage and driven to rotate by the exhaust gas, and the exhaust catalyst, and is integrally formed with the exhaust pipe,
the additive dispersion plate has a bottom wall portion having a wall surface against which the additive injected from the additive valve hits, and a side wall portion connected to an edge portion of the bottom wall portion and extending along an extension direction of the exhaust pipe ,
The side wall portion is provided with a notch portion through which the additive that hits the wall surface of the bottom wall portion and is reflected toward the side wall portion passes. The exhaust purification device according to claim 1, wherein the cutout portion is provided so as to extend to the downstream end of the side wall portion. the additive dispersion plate divides a portion of an area in the exhaust pipe into a first space located on the additive valve side and a second space located on the opposite side of the additive valve,
An inlet through which the exhaust gas flows into the first space is provided at an upstream end of the additive dispersion plate,
an outlet through which the additive injected from the additive valve flows out of the first space together with the exhaust gas,
3. The exhaust gas purification device according to claim 1, wherein an opening area of the inlet is smaller than an opening area of the outlet. the addition valve is disposed at an upper portion of the exhaust pipe,
4. The exhaust purification device according to claim 1, wherein the additive dispersion plate is disposed so as to incline downward from the upstream side to the downstream side of the exhaust pipe.

Images