JP2020204310A - Holding structure for addition valve - Google Patents

Abstract

To provide a holding structure for an addition valve capable of preventing accumulation of deposit at a spray passage outlet.SOLUTION: A holding structure for an addition valve includes: an addition valve 20 adding an additive to exhaust gas of an internal combustion engine; a holder 10 holding the addition valve 20; an exhaust manifold 30; and a gasket 40 sandwiched between the holder 10 and the exhaust manifold 30. An exhaust passage 31 is provided in the exhaust manifold 30. A spray passage 11 extending from a tip 21 of the addition valve 20 to the exhaust passage 31 is provided in the holder 10. The additive is sprayed from the tip 21 of the addition valve 20 into the spray passage 31. A hole 40h allowing the spray to reach the exhaust passage 31 is provided to continue to an outlet 13 of the spray passage 11. A coating 41 is provided on the surface of the gasket 40 around the hole 40h to expose to the spray supplied from the spray passage 11, as a layer for preventing deposit.SELECTED DRAWING: Figure 2

Description

The present invention relates to a holding structure of an add-on valve.

For the purpose of eliminating clogging in the filter (DPF: Diesel Particulate Filter) that removes PM (particulate matter) in the exhaust gas of a diesel engine, an addition valve is provided on the upstream side of the DPF, and light oil etc. injected from there is added. There is a mechanism that raises the temperature in the DPF by the agent to burn and remove (regenerate) PM.

This additive valve injects the additive into the high temperature exhaust gas containing PM. As a result, when the three elements of so-called deposit generation (HC (Hydrocarbon), soot, and temperature) are aligned, a deposit is deposited at the tip (spray hole) of the addition valve or its peripheral part, and finally the deposit is deposited. There is a problem that the vicinity of the tip of the add-on valve is covered by this, making injection impossible.

As a technique for preventing this, for example, in Japanese Patent Application Laid-Open No. 2011-106430 (Patent Document 1), the shape of the spray passage connecting the tip of the addition valve and the exhaust passage is a wide-angle fan shape. This prevents interference between the diffusion range of the spray fuel and the spray passage. Deposits are prevented by eliminating the supply of HC to the wall surface of the spray passage.

The above structure theoretically prevents the spray from interfering with the spray passage, but in the actual engine operating environment, the spray is not limited to a narrow-angle fan shape due to complicated flow such as exhaust speed change or exhaust pulsation. Will spread to. For this reason, there is a problem that a part of the spray reaches the spray passage and mixes with the exhaust gas to generate a deposit on the wall surface of the spray passage and accumulate it. When a deposit is deposited on the wall surface of the spray passage, the spray interferes with the surface layer of the deposit, and the deposit grows. Fortunately, the deposit may peel off, but eventually the tip of the additive valve is covered with the deposit, and the amount of additive to be injected is reduced, or in the worst case, injection is completely impossible.

If the injection from the addition valve is insufficient or impossible, the regeneration of the DPF may be insufficient.

Japanese Unexamined Patent Publication No. 2011-106430

FIG. 6 is a cross-sectional view showing a holding structure of a conventional addition valve. As shown in FIG. 6, in the addition valve holding structure 1, the addition valve 20 is held by the holder 10 fixed on the exhaust manifold. The tip 21 of the addition valve 20 is exposed in the spray passage 11. A water jacket 12 is arranged around the spray passage 11. Cooling water is flowed through the water jacket 12 to cool the spray passage 11 and the tip 21 of the addition valve 20. The spray passage 11 is connected to the exhaust passage 31.

In this structure, a small-diameter spray passage 11 having a diameter of about 6 mm is provided between the tip 21 and the exhaust passage 31. In this case, the small-diameter spray passage 11 and the spray (diffusion range) interfere with each other, but the small-diameter spray passage 11 can still separate the tip 21 from the exhaust gas. As a result, it is possible to prevent PM from reaching the tip 21. Further, by cooling the tip 21 and the spray passage 11 with the water jacket 12, these temperatures can be reduced. Therefore, when considering the three elements of the deposit, it is possible to reduce the PM and the temperature, so that it is possible to prevent the deposit from being generated up to the tip 21 and the middle of the spray passage 11.

However, since PM reaches the outlet 13 of the spray passage 11 (the intersection of the exhaust passage 31 and the spray passage 11), HC exists, and the temperature is high, there is a problem that a deposit is accumulated in this portion. was there.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a holding structure for an add-on valve capable of preventing deposit accumulation at the outlet of a spray passage.

The holding structure of the addition valve according to the present invention is sandwiched between an addition valve that adds an additive to the exhaust gas of an internal combustion engine, a holder that holds the addition valve, an exhaust manifold to which the holder is attached, and a holder and an exhaust manifold. Provided with a gasket. The exhaust manifold is provided with an exhaust passage through which exhaust gas flows. A spray passage extending from the tip of the addition valve to the exhaust passage is provided in the holder, and the additive is sprayed into the spray passage from the tip of the addition valve. The gasket is provided with a hole that allows the spray of the additive from the spray passage to reach the exhaust passage so as to be connected to the outlet of the spray passage, and is exposed to the spray supplied from the spray passage around the hole. As described above, a layer for preventing deposit is provided on the surface of the gasket.

In the holding structure of the add-on valve configured in this way, a layer for preventing deposits is provided on the gasket surface so as to be exposed to the spray supplied from the spray passage around the holes, so that the deposits can be deposited around the holes. Accumulation can be prevented. Further, since the layer for preventing the accumulation of deposits is provided on the surface of the gasket, the layer for preventing deposits is held by the existing gasket. As a result, it is possible to hold the layer that prevents deposits with a simple configuration without adding a new structure for holding the layer that prevents deposits.

Preferably, the layer that prevents deposits is a coating. In this case, a layer for preventing deposits can be formed only by coating the surface of the gasket, and a layer for preventing deposits can be manufactured by a simple method.

Preferably, the spray passage is fan-shaped in cross section along the axial direction, with an inner diameter increasing as it approaches the exhaust passage. In this case, since the inner diameter of the spray passage increases as it approaches the exhaust passage, the shape of the spray passage becomes close to the diffusion shape of the spray, and it becomes difficult for the spray to come into contact with the wall surface of the spray passage. As a result, deposit accumulation can be suppressed near the outlet of the spray passage.

Preferably, the gasket and the deposit-preventing layer extend from the exhaust manifold toward the add-on valve along the wall surface of the spray passage so that the deposit-preventing layer is on the inside. In this case, since the layer for preventing deposits extends along the wall surface of the spray passage so as to be inside, it is possible to prevent the accumulation of deposits on the wall surface of the spray passage as well.

Preferably, the gasket and the deposit-preventing layer are bent at the outlet of the spray passage to form a space that extends away from the addition valve and communicates with the spray passage, with the deposit-preventing layer facing the space. Have been placed. In this case, since a layer for preventing deposits is arranged so as to face the space communicating with the spray passage and surround the space, even if the spray of the additive is supplied from the spray passage to the space communicating with the spray passage, the deposit surrounding the space. A layer that prevents deposits can prevent deposits from accumulating.

It is possible to provide a holding structure of an addition valve capable of preventing deposit accumulation at the outlet of the spray passage.

It is a figure which shows the holding structure 1 of the addition valve according to Embodiment 1, and is the figure which omitted the gasket. It is a figure which shows the holding structure 1 of the addition valve according to Embodiment 1, and is the figure which shows the periphery of the connection part between a holder 10 and an exhaust manifold 30. It is a figure which shows the holding structure 1 of the addition valve according to Embodiment 2, and is the figure which shows the periphery of the connection part between a holder 10 and an exhaust manifold 30. It is a figure which shows the holding structure 1 of the addition valve according to Embodiment 3, and is the figure which shows the periphery of the connection part between a holder 10 and an exhaust manifold 30. It is a figure which shows the holding structure 1 of the addition valve according to Embodiment 4, and is the figure which shows the periphery of the connection part between a holder 10 and an exhaust manifold 30. It is sectional drawing which shows the holding structure 1 of the conventional addition valve.

Hereinafter, embodiments of the present invention will be described. In the following embodiments, the same or corresponding parts are given the same reference numbers, and the description thereof will not be repeated. It is also possible to combine each embodiment.

(Embodiment 1)
(Explanation of configuration)
FIG. 1 is a diagram showing a holding structure of an add-on valve according to the first embodiment. FIG. 2 is a diagram showing the holding structure 1 of the addition valve according to the first embodiment, and is a diagram showing the periphery of the connection portion between the holder 10 and the exhaust manifold 30.

As shown in FIGS. 1 and 2, the addition valve holding structure 1 according to the first embodiment has a holder 10 for holding the addition valve 20 and an exhaust manifold 30 on which the holder 10 is placed. .. The holder 10 is provided separately from the exhaust manifold 30.

An addition valve 20 is fitted in the holder 10. The additive is injected from the tip 21 of the addition valve 20. The holder 10 is provided with a spray passage 11 for guiding the additive sprayed from the tip 21.

The additive injected from the addition valve is light oil or the like as long as it is an additive for DPF. Further, if it is SCR (Selective Catalytic Reduction) that purifies nitrogen oxides in exhaust gas, it is urea or the like.

A water jacket 12 for cooling the addition valve 20 and the spray passage 11 is provided in the holder 10. Cooling water for cooling the engine is flowed through the water jacket 12. The water jacket 12 can cool the spray passage 11 and the addition valve 20 to suppress deposit accumulation.

The exhaust manifold 30 is provided with an exhaust passage 31 through which exhaust gas discharged from the combustion chamber of the internal combustion engine flows. Exhaust flows in the exhaust passage 31 in the direction indicated by the arrow 35. The exhaust gas is hot, and the exhaust gas contains PM generated by incomplete combustion of the additive.

As shown in FIG. 2, a gasket 40 is provided between the holder 10 and the exhaust manifold 30. The gasket 40 is made of, for example, stainless steel or copper, and has a function of preventing exhaust gas from leaking between the exhaust manifold 30 and the holder 10.

The surface of the gasket 40 is provided with a coating 41 as a thin layer to prevent deposits. The coating 41 is a kind of surface treatment. Materials constituting the coating 41 include a coating obtained by adding graphite to molybdenum disulfide, a fluorine-based resin coating, a glass-based coating containing silica as a main component, a silicon carbide (SiC) coating by a CVD method, and a diamond-like carbon (DLC). There is a coating etc.

The material of the coating 41 is not limited to these, and may be any material that can prevent the accumulation of deposits. The coating 41 may be configured, for example, by plating.

In the gas seal portion 32, the gasket 40 is sandwiched between the exhaust manifold 30 and the holder 10 to prevent exhaust gas from leaking. Since exhaust gas does not leak into the opening 33 of the exhaust manifold 30, the gasket 40 is not normally required. However, a gasket 40 is also provided in the opening 33 to hold the coating 41.

The gasket 40 is provided with a hole 40h. The coating 41 is also provided with holes 41h so as to correspond to the holes 40h. The holes 40h and 41h have a circular shape when viewed from the axial direction (direction in which the spray passage 11 extends). In the cross section shown in FIG. 2, the holes 40h and 41h communicate with the spray passage 11. Therefore, when the additive is sprayed from the tip 21 of the addition valve 20, the spray reaches the inside of the exhaust passage 31 via the spray passage 11, the holes 40h and 41h.

That is, in the holding structure 1 of the addition valve 20 in the first embodiment, the addition valve 20 for adding an additive to the exhaust gas of the internal combustion engine, the holder 10 for holding the addition valve 20, and the exhaust manifold 30 to which the holder 10 is attached are attached. And a gasket 40 sandwiched between the holder 10 and the exhaust manifold 30, the exhaust manifold 30 is provided with an exhaust passage 31 through which exhaust gas flows, and a spray extending from the tip 21 of the add-on valve 20 to the exhaust passage 31. A hole in which the passage 11 is provided in the holder 10 and the additive is sprayed into the spray passage 11 from the tip 21 of the addition valve 20 so that the spray of the additive from the spray passage 11 reaches the exhaust passage 31. The gasket 40 is provided so that 40h is connected to the outlet 13 of the spray passage 11, and the surface of the gasket 40 is coated as a layer to prevent deposits so as to be exposed to the spray supplied from the spray passage 11 around the hole 40h. 41 is provided.

(Explanation of effect)
At the outlet 13 of the spray passage 11, a coating 41 is provided on the surface of the gasket 40 so as to be exposed to the spray supplied from the spray passage 11 in order to exert a function of not accumulating deposits. Therefore, even if the three elements (temperature, PM, and HC) for deposit deposition are aligned around the coating 41, it is possible to prevent the deposit from accumulating on the surface of the coating 41. As a result, it does not cause problems due to deposit accumulation.

The gasket 40 that holds the coating 41 has existed conventionally, and is not newly provided only by changing the shape. As a result, the coating 41 can be retained without adding new members.

Since the spray passage 11 and the tip 21 of the addition valve 20 are cooled by the water jacket 12, the temperature rise can be suppressed. Furthermore, since the concentration of PM is low, it is possible to prevent the accumulation of deposits.

Since the gasket 40 is cheaper than the holder 10 and is a part that can be easily replaced at the time of disassembly, even if the coating 41 is peeled off or deteriorated, the gasket 40 with the coating 41 can be replaced inexpensively and easily. ..

As a secondary effect, the gas sealing performance between the holder 10 and the exhaust manifold 30, which is the original function of the gasket 40, can be further improved by incorporating the gas sealing property improving effect in addition to the deposit adhesion prevention effect into the function of the coating 41.

(Embodiment 2)
FIG. 3 is a diagram showing the holding structure 1 of the addition valve according to the second embodiment, and is a diagram showing the periphery of the connection portion between the holder 10 and the exhaust manifold 30. As shown in FIG. 3, in the second embodiment, the inner diameter of the spray passage 11 is larger on the downstream side, that is, on the side far from the tip 21 of the addition valve 20. In other words, the inner diameter of the spray passage 11 increases as it approaches the exhaust passage 31. In the cross section shown in FIG. 3, the spray passage 11 is fan-shaped.

The additive injected from the tip 21 of the addition valve 20 passes through the spray passage 11 while advancing in the axial direction of the spray passage 11 and diffusing in the lateral direction orthogonal to the axial direction. Therefore, the width of the spray becomes larger due to diffusion as it goes downstream. When the spray and the spray passage 11 come into contact with each other, deposits are likely to be accumulated at that portion. Therefore, in order to prevent the deposit from being accumulated, it is better not to bring the spray and the spray passage 11 into contact with each other. In the second embodiment, since the width of the spray passage 11 is widened on the downstream side where the width of the spray is widened, contact between the spray and the spray passage 11 can be prevented, and deposit accumulation can be prevented.

(Embodiment 3)
FIG. 4 is a diagram showing the holding structure 1 of the addition valve according to the third embodiment, and is a diagram showing the periphery of the connection portion between the holder 10 and the exhaust manifold 30. As shown in FIG. 4, the third embodiment is different from the second embodiment in that the gasket 40 and the coating 41 are provided in the spray passage 11 having a fan-shaped cross section. The bent portion 40a of the gasket 40 and the bent portion 41a of the coating 41 both extend along the wall surface of the spray passage 11.

That is, the gasket 40 and the coating 41 extend from the exhaust manifold 30 toward the addition valve 20 along the wall surface of the spray passage 11 so that the coating 41 is on the inside.

In this embodiment, since the bent portion 41a of the coating 41 is provided on the wall surface of the fan-shaped spray passage 11, it is possible to effectively suppress the accumulation of deposits on the wall surface of the spray passage 11. That is, since the shape of the gasket 40 is formed into a fan shape similar to that of the spray passage 11, the spray passage 11 portion other than the lower surface flat portion at the outlet 13 can be similarly covered with the coating 41. At this time, since most of the gaskets 40 are manufactured by press-molding a metal plate, a shape such as a fan shape can be easily and inexpensively manufactured by press-molding.

(Embodiment 4)
FIG. 5 is a diagram showing the holding structure 1 of the addition valve according to the fourth embodiment, and is a diagram showing the periphery of the connection portion between the holder 10 and the exhaust manifold 30. As shown in FIG. 5, in the fourth embodiment, the lamination directions of the gasket 40 and the coating 41 are opposite to those of the first to third embodiments. The tip of the gasket 40 is bent to form the protrusion 40b. The protrusion 40b of the gasket 40 and the protrusion 41b of the coating 41 are arranged so as to surround a predetermined space 40s. The space 40s communicates with the spray passage 11. A protrusion 41b of the coating 41 is provided so as to be exposed in the space 40s. The space 40s is columnar.

That is, the gasket 40 and the coating 41 are bent at the outlet 13 of the spray passage 11 to form a space 40s extending in a direction away from the addition valve 20 and communicating with the spray passage 11, facing the space 40s. The coating 41 is arranged so as to surround the space 40s.

The additive injected from the tip 21 of the addition valve 20 flows into the space 40s and the exhaust passage 31 via the spray passage 11. In this embodiment, the coating 41 is provided only on one side of the gasket 40, but the coatings 41 may be provided on both sides of the gasket 40.

In this embodiment, since the coating 41 is provided at the outlet 13 so as to be exposed to the space 40s, it is possible to prevent the accumulation of deposits. That is, by providing the coating 41 inside the protrusion 40b of the gasket 40 continuous from the outlet 13 portion of the spray passage 11, deposit adhesion can be prevented.

Since the outlet 13 portion of the spray passage 11 can be further separated from the exhaust gas by the gasket 40 and its protrusion 40b, PM reduction and temperature drop can be further improved, and deposit generation can be prevented. If the shape of the protrusion 40b is a metal gasket 40, it can be easily and inexpensively manufactured by press molding as in the third embodiment.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims rather than the above-described embodiment, and is intended to include meaning equivalent to the scope of claims and all modifications within the scope.

1 Addition valve holding structure, 10 holder, 11 spray passage, 12 water jacket, 13 outlet, 20 addition valve, 21 tip, 30 exhaust manifold, 31 exhaust passage, 32 gas seal, 33 opening, 35 arrow, 40 gasket , 40a, 41a Bent part, 40b, 41b protrusion, 40h, 41h hole, 40s space, 41 coating.

Claims (5)

An add-on valve that adds an additive to the exhaust gas of an internal combustion engine,
A holder that holds the add-on valve and
The exhaust manifold to which the holder is attached and
A gasket sandwiched between the holder and the exhaust manifold is provided.
The exhaust manifold is provided with an exhaust passage through which exhaust gas flows.
A spray passage extending from the tip of the addition valve to the exhaust passage is provided in the holder, and the additive is sprayed into the spray passage from the tip of the addition valve.
The gasket is provided in a hole that allows the spray of the additive from the spray passage to reach the exhaust passage so as to be connected to the outlet of the spray passage, and is supplied from the spray passage around the hole. A holding structure of an add-on valve in which a layer for preventing deposit is provided on the surface of the gasket so as to be exposed to the spray. The holding structure of an add-on valve according to claim 1, wherein the layer for preventing the deposit is formed by a coating. The addition valve holding structure according to claim 1 or 2, wherein the spray passage has an inner diameter that increases as it approaches the exhaust passage, and is fan-shaped in a cross section along the axial direction. The third aspect of the present invention, wherein the gasket and the deposit-preventing layer extend from the exhaust manifold toward the addition valve along the wall surface of the spray passage so that the deposit-preventing layer is on the inside. Retaining structure of the addition valve. The gasket and the layer for preventing the deposit are bent at the outlet of the spray passage to form a space extending in a direction away from the addition valve and communicating with the spray passage so as to face the space and surround the space. The holding structure for an add-on valve according to claim 1 or 2, wherein a layer for preventing the deposit is arranged therein.

Images