JP5041151B2 - 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 including an additive injection valve that supplies an additive to a catalyst provided in an exhaust passage.

In the exhaust passage of a diesel engine, NOx (nitrogen oxide) and particulate matter (hereinafter referred to as PM) contained in the exhaust are prevented from being released into the atmosphere, in order to prevent NOx storage catalyst and diesel particulate filter ( Hereinafter referred to as DPF).
The NOx occlusion amount of the NOx occlusion catalyst and the amount of PM trapped by the DPF are limited, so-called NOx purge for releasing and reducing the stored NOx, and so-called forced regeneration for burning and removing the PM collected by the DPF. There is a need.

Therefore, an NOx storage catalyst or an oxidation catalyst is provided upstream of the DPF, an additive such as fuel (HC) is supplied to the oxidation catalyst, and NOx purge or forced regeneration is performed using the oxidation reaction in the oxidation catalyst. There is a configuration to do.
In addition, the addition of fuel (HC) to the oxidation catalyst has a configuration in which a fuel addition injector is provided on the exhaust upstream side of the oxidation catalyst and fuel (HC) is injected from the fuel addition injector.

However, in the fuel addition injector, if the fuel injection port is directly exposed to high-temperature exhaust gas, there is a risk that the heat-resistant temperature may be exceeded, and the fuel (HC) adhering to the vicinity of the fuel injection port may be carbonized or PM may be attached. There is a risk of clogging.
Therefore, a fuel addition injector is provided at a position separated from the exhaust passage in the branch portion of the exhaust pipe, and the injected fuel injected from the fuel addition injector exhausts through the conical injection space (injection passage). The structure added in a pipe | tube is disclosed (refer patent document 1).
JP 2004-197635 A

In the technique disclosed in Patent Document 1, the injection space has a conical shape with the tip of the nozzle that is the fuel injection port of the fuel addition injector as the apex and an apex angle larger than the fuel injection angle. In such a configuration, the interval between the wall surface of the injection space and the injected fuel is narrow, and fuel (HC) may adhere to the wall surface.
Further, when fuel (HC) is injected from the fuel addition injector, the gas in the injection space flows into the exhaust pipe together with the injected fuel, so that the pressure in the injection space decreases and becomes negative pressure. The fuel injection angle has an expanded injection shape, and fuel (HC) adheres to the wall surface.

If the fuel (HC) adheres to the wall surface of the injection space, deposits due to carbonization of the fuel (HC), PM adhesion, etc. accumulate, the injection space is closed, and the fuel is added to the oxidation catalyst by the injector for fuel addition. There is a problem that the addition of fuel (HC) is blocked.
However, if the apex angle of the injection space is increased so as to widen the interval between the injection space and the injected fuel, the injection space becomes larger in diameter, making it difficult to ensure strength and difficult to mold, which is not preferable.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to have a simple configuration and an injection shape in which the additive injection injected from the additive injection valve does not adhere to the wall surface of the injection passage. It is an object of the present invention to provide an exhaust gas purification apparatus for an internal combustion engine that can maintain a good quality and can maintain a good supply of additives to a catalyst.

In order to achieve the above object, in the exhaust gas purification apparatus for an internal combustion engine according to claim 1, a catalyst provided in an exhaust pipe of the internal combustion engine, an additive injection valve for supplying an additive to the exhaust upstream side of the catalyst, An injection passage that communicates with the inside of the exhaust pipe and injects an additive from the additive injection valve, one end is connected to the additive injection valve side of the injection passage, and the other end is connected to the exhaust pipe. , and a said additive injection valve inflow possible gas inflow gas into side passage of the injection duct, the gas inlet passage extending into said exhaust pipe serving as the other end of the additive injection valve side as the end The groove portion communicates a low pressure portion where the pressure is reduced by additive injection on the additive injection valve side of the injection passage and a high pressure portion where the pressure is higher than the low pressure portion outside the injection passage, injection hole at one end of the groove the additive injection valve Ri is characterized by being located on the upstream side.

According to the exhaust gas purification apparatus for an internal combustion engine of the present invention using the above means, the additive is supplied to the catalyst provided in the exhaust pipe through the injection passage and the gas is supplied to the additive injection valve side of the injection passage. Is provided with a gas inflow passage.
That is, when the gas in the injection passage flows into the exhaust pipe together with the additive injection injected from the additive injection valve, the gas flows into the injection passage through the gas inflow passage. A decrease in the atmospheric pressure in the passage is suppressed.

Thereby, the shape of the fuel injection injected from the additive injection valve can be maintained, and adhesion of the additive to the wall surface of the injection passage can be prevented.
Further, the gas inflow passage is a groove portion that communicates the low pressure portion in the injection passage where the atmospheric pressure is lowered when the additive is injected by the additive injection valve and the high pressure portion where the atmospheric pressure is higher than the low pressure portion.

Therefore, the gas can surely flow through the gas inflow passage into the injection passage having a low pressure when the additive is injected by the additive injection valve.
Thereby, the fall of the atmospheric | air pressure in an injection channel can be suppressed reliably.
Furthermore, the one end part of the groove part is located upstream from the injection hole of the additive injection valve.

As a result, since a uniform flow is generated along the injection from the upper part of the injection hole of the additive injection valve, adhesion of the additive on the wall surface of the injection passage to the injection valve tip including the injection hole part is further suppressed. Can be made.
Further , one end of the gas inflow passage is connected to the additive injection valve side of the injection passage, and the other end is connected to the exhaust pipe.

As a result, the gas is introduced from the same exhaust pipe as the exhaust pipe communicating with the injection passage, so that there is little influence on the engine control.
Further, the gas inflow passage is formed in the wall surface of the injection passage as a groove portion extending from the additive injection valve side into the exhaust pipe, so that the gas in the injection passage is injected together with the injected fuel injected from the additive injection valve. While flowing into the exhaust pipe and reducing the pressure in the injection passage, the gas flows into the injection passage on the additive injection valve side in the groove where the injected fuel does not pass.

Thereby, the gas inflow passage can be formed by processing the wall surface of the injection passage, and the pressure drop in the injection passage can be suppressed .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
Referring to FIGS. 1 to 3, FIG. 1 is a schematic configuration diagram of an exhaust purification system for an internal combustion engine according to a first embodiment of the present invention, and FIG. 2 is an exhaust purification of the internal combustion engine according to the first embodiment of the present invention. FIG. 3 shows an enlarged vertical cross-sectional view of the main part of the apparatus, and FIG. 3 shows a cross-sectional view taken along line AA of FIG.

An engine (internal combustion engine) 1 shown in FIG. 1 is a diesel engine that is driven using light oil (HC) as fuel.
One end of an exhaust manifold 2 is connected laterally to the side surface of the engine 1, and a supercharger 4 is connected to the other end of the exhaust manifold 2.
The turbocharger 4 is a turbocharger, and a compressor is provided in an intake passage (not shown), and a turbine is provided in an exhaust passage.

An exhaust pipe 10 is connected to the exhaust downstream side of the supercharger 4.
In the exhaust pipe 10, an oxidation catalyst 12 (catalyst), a NOx storage catalyst 14, and a particulate filter (hereinafter referred to as DPF) 16 are provided in this order from the exhaust upstream side.
Specifically, the exhaust pipe 10 is formed with a branch portion 10a branched downward from a connection portion with the supercharger 4, and an oxidation catalyst 12 is provided on the exhaust downstream side of the branch portion 10a. The oxidation catalyst 12 is formed by supporting a catalyst noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh) on a porous wall forming a passage, and oxidizes CO, HC, etc. in exhaust gas. causes and converted by the CO ₂ and H _{2 O,} has the function of raising the temperature of the exhaust by the oxidation reaction.

  The NOx storage catalyst 14 and the DPF 16 are provided in the exhaust pipe 10 in the exhaust downstream side portion extending in the lateral direction. The NOx occlusion catalyst 14 performs so-called NOx purging that occludes NOx in exhaust gas and releases and reduces the occluded NOx when a reducing agent such as HC is supplied. The DPF 16 collects PM in the exhaust gas, and performs so-called forced regeneration in which the collected PM is incinerated and removed by raising the temperature.

A fuel addition injector 20 is provided on the upper surface portion of the branch portion 10a of the exhaust pipe 10 so as to be substantially extended in the axial direction of the oxidation catalyst 12 and supply fuel (HC) as an additive to the oxidation catalyst 12. (Additive injection valve) is disposed through the support member 22.
Specifically, as shown in FIGS. 2 and 3, the fuel addition injector 20 is supported on the upper portion of the support member 22 erected on the outside of the exhaust pipe 10 so as to be directed toward the center of the inlet end surface of the oxidation catalyst 12. Yes.

Inside the support member 22, a fuel injection port 20a (injection hole) at the tip of the fuel addition injector 20 protrudes and the injected fuel 24 injected conically from the fuel injection port 20a passes. An injection passage 26 is formed.
The injection passage 26 is a cylindrical passage having a fuel injection port portion 20a of the fuel addition injector 20 as an upper end and extending in a direction in which the oxidation catalyst 12 is present, and the lower end is an opening formed in the upper surface of the exhaust pipe 10. It communicates with the inside of the exhaust pipe 10 via the portion 10b.

The diameter of the injection passage 26 is formed such that the injected fuel 24 is accommodated inside the passage wall surface with a gap. That is, the lower end portion of the injection passage 26 is formed so that the diameter of the injection passage 26 is larger than the diameter of the conical injection fuel 24.
The support member 22 has a groove 28 formed on the wall surface of the injection passage 26 extending from the upper end (one end) to the lower end (the other end) along the axial direction of the injection passage.

  The groove portion 28 is formed at eight positions at equal intervals in the circumferential direction in the radial direction with respect to the axial direction of the injection passage 26, that is, the fuel injection direction, as viewed in the cross section of FIG. Each of the groove portions 28 is formed in a shape extending outward from the upper end of the injection passage 26 on the fuel addition injector 20 side toward the opening 10b of the exhaust pipe 10. The groove 28 extends outward as it goes parallel to the injected fuel 24 or downward so as to be larger than the injection angle of the injected fuel 24, and the upper end located on the fuel addition injector 20 side is the fuel addition injector. It is located above (upstream side) 20 fuel injection ports 20a.

Further, an ECU (not shown) is electrically connected to the fuel addition injector 20, and the ECU detects the NOx occlusion amount of the NOx occlusion catalyst 14 and the PM trapping amount of the DPF 16, and requires NOx purge or forced regeneration. Is determined, the fuel addition injector 20 is controlled to add fuel (HC) to the oxidation catalyst 12.
The operation of the exhaust gas purification apparatus for an internal combustion engine according to the first embodiment of the present invention constructed as above will be described below.

During the operation of the engine 1, when performing NOx purge of the NOx storage catalyst 14 or forced regeneration of the DPF 16, fuel injection by the fuel addition injector 20 is performed under the control of the ECU.
The injected fuel 24 injected by the fuel addition injector 20 flows into the exhaust pipe 10 through the injection passage 26, and fuel (HC) is added to the oxidation catalyst 12.

  An oxidation reaction occurs in the oxidation catalyst 12 to which fuel (HC) is added, and the temperature of the exhaust is raised by the heat of the oxidation reaction. Then, the exhaust gas whose temperature has been raised and the fuel (HC) that has not been oxidized by the oxidation catalyst 12 flow into the NOx catalyst 14 on the exhaust downstream side, whereby NOx purge is performed. Further, in the DPF 14, the exhaust gas whose temperature has been raised by the oxidation catalyst 12 flows in, whereby PM is incinerated and removed, and forced regeneration is performed.

Here, the action when the injected fuel 24 injected from the fuel addition injector 20 passes through the injection passage 26 in the support member 22 will be described in detail.
The injected fuel 24 injected from the fuel injection port 20 a of the fuel addition injector 20 flows into the exhaust pipe 10 together with the gas near the injected fuel 24. Thereby, the atmospheric pressure in the vicinity of the fuel injection port 20a of the fuel addition injector 20 having a particularly high flow velocity in the injection passage 26 is lowered.

  On the other hand, in the groove portion 28 formed on the wall surface of the injection passage 26, the injected fuel 24 does not pass and the area in contact with the injection passage 26 is small, so that it is not easily affected by the flow of the injected fuel 24. Since the groove portion 28 communicates the vicinity of the fuel injection port portion 20a of the injection passage 26 with the inside of the exhaust pipe 10, the inside of the groove portion 28 has a relatively high pressure from the exhaust pipe 10 having a relatively high pressure. The gas flows to the vicinity of the low fuel injection port 20a.

Thereby, the fall of the atmospheric pressure in the injection passage 26 is suppressed, and the injected fuel 24 flows into the exhaust pipe 10 while maintaining the injection shape as designed without changing the injection shape.
That is, the injected fuel 24 can be accommodated in the injection passage 26 as it is designed to flow into the exhaust pipe 10, and fuel (HC) can be prevented from adhering to the wall surface of the injection passage 26.
Further, since the gas from the groove portion 28 flows from the upstream side of the fuel addition injector 20, deposit accumulation due to PM adhesion at the injection hole and the tip of the injection valve can be suppressed.

Therefore, carbonization of fuel (HC) adhering to the wall surface of the injection passage 26 and deposit accumulation due to PM adhesion can be suppressed, and fuel addition by the fuel addition injector 20 can be maintained well.
Further, since the shape of the injected fuel 24 can be maintained as designed, it is not necessary to excessively enlarge the injection passage 26, and the support member 22 having sufficient strength is formed with the minimum processing only by forming the groove portion 28. can do.

As described above, the exhaust gas purification apparatus for an internal combustion engine according to the first embodiment of the present invention has an injection shape in which the injected fuel 24 injected from the fuel addition injector 20 does not adhere to the wall surface of the injection passage 26 with a simple configuration. The fuel addition to the oxidation catalyst 12 can be maintained well.
Next, a second embodiment will be described.

Referring to FIGS. 4 to 6, FIG. 4 is a schematic configuration diagram of an exhaust purification device for an internal combustion engine according to a second embodiment of the present invention, and FIG. 5 is an exhaust purification of the internal combustion engine according to the second embodiment of the present invention. FIG. 6 shows an enlarged vertical cross-sectional view of the main part of the apparatus, and FIG. 6 shows a cross-sectional view taken along line BB in FIG. In the second embodiment, description of the same configuration as in the first embodiment is omitted.
In the second embodiment, a fuel addition injector for adding fuel (HC) to the oxidation catalyst 12, located on the upper surface portion of the branch portion 30 a of the exhaust pipe 30, substantially extending in the axial direction of the oxidation catalyst 12. 40 (fuel injection valve) is disposed via a support member 42.

Specifically, as shown in FIGS. 5 and 6, the fuel addition injector 40 is supported on an upper portion of a support member 42 erected on the outside of the exhaust pipe 30 so as to be directed toward the center of the inlet end surface of the oxidation catalyst 12. Yes.
A fuel injection port 40a (injection hole) at the tip of the fuel addition injector 40 protrudes inside the support member 42, and the injected fuel 44 injected conically from the fuel injection port 40a passes therethrough. An injection passage 46 is formed.

The injection passage 46 is a cylindrical passage having a fuel injection port portion 40 a of the fuel addition injector 40 as an upper end and extending in a direction in which the oxidation catalyst 12 is present, and a lower end is an opening formed in the upper surface of the exhaust pipe 30. It communicates with the inside of the exhaust pipe 30 via the part 30b.
The diameter of the injection passage 46 is formed so that the injected fuel 44 is accommodated inside the passage wall surface with a gap. That is, the lower end portion of the injection passage 46 is formed so that the diameter is larger than the diameter of the cross section of the injected fuel 44.

  Further, a gas inflow hole 48 (gas inflow passage) penetrating outward is formed in the upper portion of the injection passage 46, that is, in the side wall surface near the fuel injection port portion 40a of the fuel addition injector 40. The gas inflow hole 48 is connected to one end of a gas inflow pipe 50 (gas inflow passage) connected to the outside of the support member 42, and the other end of the gas inflow pipe 50 is on the exhaust downstream side of the opening 30b. It is connected to the opening 30c of the exhaust pipe 30 formed in the above. That is, the upper portion of the injection passage 46 is communicated with the inside of the exhaust pipe 10 through the gas inflow passage including the gas inflow hole 48 and the gas inflow pipe 50.

  In the exhaust gas purification apparatus for an internal combustion engine according to the second embodiment of the present invention thus configured, the injected fuel 44 injected from the fuel addition injector 40 and passing through the injection passage 46 is a gas in the vicinity of the injected fuel 44. At the same time, it flows through the injection passage 46 and into the exhaust pipe 30. As a result, the air pressure in the vicinity of the fuel injection port 40a of the fuel addition injector 40 having a particularly high flow velocity in the injection passage 46 decreases.

Since the upper part of the injection passage 46 communicates with the inside of the exhaust pipe 30 via the gas inflow hole 48 and the gas inflow pipe 50, the gas inflow hole 48 and the inside of the exhaust pipe 30 having a relatively high atmospheric pressure. Gas (exhaust gas) flows through the gas inflow pipe 50 into the injection passage 46 having a relatively low atmospheric pressure.
Moreover, since the gas from the gas inflow hole 48 flows in from the upstream side of the fuel injection port portion 40a of the fuel addition injector 20, PM adhesion at the injection hole and the tip of the injection valve can also be suppressed.

As a result, the pressure drop in the injection passage 46 is suppressed, and the injected fuel 44 flows into the exhaust pipe 30 while maintaining the injection shape as designed without changing the injection shape.
Further, the air in the injection passage 46 flows out into the exhaust pipe 30 due to the fuel injection by the fuel addition injector 40. However, since the injection passage 46 and the gas inflow passage are isolated, there is no influence from this. The gas can flow into the injection passage 46.

Thus, in the second embodiment, the same effect as in the first embodiment can be obtained, and in the second embodiment, the shape of the injection passage 46 is not changed, and the inside of the injection passage 46 is not particularly changed. The decrease in the atmospheric pressure can be suppressed.
Although the description of the embodiment of the exhaust gas purification apparatus for an internal combustion engine according to the present invention is finished above, the embodiment is not limited to the above embodiment.

  In the first embodiment, the groove 28 has a rectangular shape outward from the wall surface of the injection passage 26 as shown in FIG. 3, but is not limited to such a shape. For example, as shown in FIG. 7 as a modified example, each groove portion 60 may have an end surface shape that expands outward from the wall surface of the injection passage 62. That is, the cross section of the groove 60 has a substantially triangular shape that narrows toward the center of the injection passage 62. By setting the groove portion 60 having such a cross-sectional shape, an area where the groove portion 60 and the injection passage 62 are in contact with each other is reduced, so that the inside of the groove portion 60 is further less affected by the flow of the injected fuel 64. Thereby, at the time of fuel injection by the fuel addition injector, the flow of gas from the exhaust pipe passing through the groove 60 to the injection passage 62 can be made smoother.

In the second embodiment, the gas inflow passage including the gas inflow hole 48 and the gas inflow pipe 50 communicates the upper portion of the injection passage 46 and the branch portion 30b exhaust downstream portion of the exhaust pipe 30. The gas inflow passage is not limited to the configuration.
For example, as shown in FIG. 8 as a modification, the other end of the gas inflow pipe 70 may be connected to the exhaust pipe 74 at the exhaust downstream position of the oxidation catalyst 72. With this configuration, the exhaust gas (gas) purified by the oxidation catalyst 72 can flow into the injection passage during fuel injection by the fuel addition injector 40, and the fuel (HC) on the wall surface of the injection passage 46 can be introduced. Adhesion and adhesion of PM can be suppressed more favorably.

  As another modified example, as shown in FIG. 9, a check valve 78 capable of allowing outside air to flow into the other end of the gas inflow pipe 76 may be provided. With such a configuration, the fuel (HC) on the wall surface of the injection passage 46 can flow outside air (gas) that does not contain HC and PM into the injection passage 46 during fuel injection by the fuel addition injector 40. ) Adhesion and PM adhesion can be better suppressed.

  Furthermore, as another modification, as shown in FIG. 10, the other end of the gas inflow pipe 80 may be connected to the exhaust manifold 82. That is, by configuring the gas inflow pipe 80 to be connected to the high-pressure turbine upstream side, the gas (exhaust gas) can be more smoothly flowed into the injection passage 46 at the time of fuel injection of the fuel addition injector 40. In addition, when the high-pressure gas flows into the injection passage 46, the injected fuel 44 is atomized, and the fuel addition to the oxidation catalyst 12 can be improved.

  In the second embodiment, only one path is formed for the gas inflow passage 48 including the gas inflow hole 48 penetrating from the upper part of the injection passage 46 to the outside and the gas inflow pipe 50 connected to the gas inflow hole 48. However, it is not limited to this. For example, two or more gas inflow passages may be provided. As a modified example, as shown in FIG. 11, gas inflow holes 86 a and 86 b extending in tangential directions from the opposing positions on the side wall surface of the injection passage 84 respectively. A configuration may be employed in which gas inflow pipes 88a and 88b that are formed and connected to the gas inflow holes 86a and 86b are provided. By providing a plurality of gas inflow passages communicating with the injection passage 84 in this way, gas can be flowed more smoothly into the injection passage. Further, by forming the gas inflow holes 88a and 88b in a shape extending in the tangential direction of the injection passage 84, the gas flowing in through the gas inflow passage flows in a spiral shape along the circumferential direction of the injection passage 84. As a result, the inflow of gas becomes even smoother.

Moreover, in the said embodiment, although the fuel addition injectors 20 and 40 are provided in the branch parts 10a and 30a in the exhaust pipes 10 and 30, a fuel addition injector is not restricted to what is provided in the said part, and fuel addition is carried out. Any structure provided on the exhaust upstream side of the catalyst may be used.
Moreover, in the said embodiment, although the fuel addition injectors 20 and 40 are standingly arranged by the upper surface of the branch parts 10a and 30a of the exhaust pipes 10 and 30, it is not restricted to such a structure, A fuel addition injector is used. You may incline and provide so that an exhaust pipe may be followed.

In the above embodiment, the exhaust gas purification device includes the oxidation catalyst 12, the NOx storage catalyst 14, and the DPF 16 in the exhaust pipes 10 and 30, but the exhaust purification device includes a catalyst for adding fuel (HC). For example, the configuration may be such that only one of the NOx storage catalyst and the DPF is provided on the exhaust gas downstream side of the oxidation catalyst.
Moreover, in the said embodiment, although the injection 24 obtained from a fuel addition injector demonstrated as a cone shape, the shape of injection is not limited to a cone.

  Furthermore, although the fuel is used as the additive in the above embodiment, the reducing agent is not limited to fuel and may be urea or the like.

1 is a schematic configuration diagram of an exhaust gas purification apparatus for an internal combustion engine according to a first embodiment of the present invention. 1 is an enlarged longitudinal sectional view of a main part in an exhaust gas purification apparatus for an internal combustion engine according to a first embodiment of the present invention. FIG. 3 is a transverse sectional view taken along line AA in FIG. 2. It is a schematic block diagram of the exhaust gas purification apparatus of the internal combustion engine which concerns on 2nd Example of this invention. It is a principal part expanded longitudinal cross-sectional view in the exhaust gas purification apparatus of the internal combustion engine which concerns on 2nd Example of this invention. It is a cross-sectional view which follows the BB line of FIG. It is a cross-sectional view showing a modification of the first embodiment. It is a schematic block diagram which shows the modification of 2nd Example. It is a schematic block diagram which shows the modification of 2nd Example. It is a schematic block diagram which shows the modification of 2nd Example. It is a schematic block diagram which shows the modification of 2nd Example.

Explanation of symbols

1 engine (internal combustion engine)
4 Supercharger 10 Exhaust pipe 10a Branch 12 Oxidation catalyst (catalyst)
14 NOx storage catalyst 16 Particulate filter (DPF)
20, 40 Fuel addition injector (additive injection valve)
20a, 40a Fuel injection port 22, 42 Support member 24, 44 Injection fuel 26, 46 Injection passage 28 Groove (gas inflow passage)
48 Gas inflow hole (gas inflow passage)
50 Gas inflow pipe (gas inflow passage)

Claims (1)

A catalyst provided in the exhaust pipe of the internal combustion engine;
An additive injection valve for supplying an additive to the exhaust upstream side of the catalyst;
An injection passage communicating with the inside of the exhaust pipe and injecting an additive from the additive injection valve;
One end is connected to the additive injection valve side of the injection passage, the other end is connected to the exhaust pipe, and comprises a gas inflow passage through which gas can flow into the additive injection valve side of the injection passage,
The gas inflow passage is a groove extending from the additive injection valve side serving as one end into the exhaust pipe serving as the other end,
The groove portion communicates a low pressure portion where the pressure is reduced by additive injection on the additive injection valve side of the injection passage and a high pressure portion where the pressure is higher than the low pressure portion outside the injection passage,
One end of the groove is located upstream of the injection hole of the additive injection valve.

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