KR20030064630A - Engine EGR apparatus - Google Patents

Abstract

The present invention can reflux the EGR gas after the removal of the SOF fraction without requiring the extension of the EGR pipe or the installation of free joints, regardless of the installation state of the catalyst in the exhaust system. In addition, the present invention provides an engine EGR apparatus capable of preventing deposit deposition on an intake system.

One end of the EGR line 7 is connected to the assembly portion of the exhaust manifold 2, and the other end is connected to the engine side mounting flange 2a, and the EGR catalyst 7 is connected to the EGR line 7. A portion of the exhaust gas flowing through the exhaust manifold 2 is refluxed as an EGR gas through the EGR pipe line 7 to the intake system of the engine, and the SOF powder in the EGR gas is removed by the catalyst 6 at that time. Remove

Description

Engine exhaust gas recirculation apparatus {Engine EGR apparatus}

The present invention relates to an EGR (EXHAUST GAS RECIRCULATION) device of an engine, and more particularly, to an EGR device capable of preventing deposit deposition by SOF powder contained in an EGR gas.

BACKGROUND OF THE INVENTION An EGR apparatus that refluxs a part of the exhaust gas discharged from an engine to reduce the combustion temperature and thereby reduces the amount of NOx (nitrogen oxide) discharged is widely used. As is well known, the exhaust gas contains SOF powder mainly composed of unburned fuel, oil, etc., and SOF powder refluxed in the intake machine together with the EGR gas is a factor for depositing deposits. Like the EGR device described in the publication, the EGR gas introduction portion of the EGR line is connected to the downstream side of the proximity catalyst provided on the exhaust manifold side of the exhaust pipe connected to the exhaust manifold, that is, the exhaust gas introduced by the EGR gas introduction portion, that is, EGR gas is refluxed to the intake system through the EGR pipe. This EGR apparatus requires the proximity catalyst although the SOF component in the EGR gas is removed by the proximity catalyst.

On the other hand, there are some vehicles in which the proximity catalyst is omitted from the cost surface or the engine output surface. In the EGR device of such a vehicle, for example, as described in Japanese Patent Application Laid-Open No. 2000-249003, the floor disposed below the bottom of the exhaust pipe EGR gas is introduced and refluxed from the downstream side of the catalyst below.

However, because the catalyst below the floor is quite separated from the engine, it is necessary to significantly extend the EGR pipeline, while bellows on the EGR pipeline to avoid the impact of the roll or vibration of the engine on the EGR pipeline. There is a problem in that it is necessary to install freely connected seams such as spherical seams, resulting in a sharp increase in manufacturing costs.

It is an object of the present invention, regardless of the installation state of the catalyst in the exhaust system, it is possible to reflux the EGR gas from which the SOF fraction has been removed without requiring the extension of the EGR pipeline or the installation of free joints, thereby reducing the manufacturing cost. In the meantime, it is providing the engine EGR apparatus which can prevent deposit deposition to an intake machine.

In order to achieve the above object, the EGR apparatus of the engine of the present invention is an EGR apparatus of an engine for returning a part of exhaust gas discharged from an engine to an intake machine through an EGR pipeline, and is installed at one end of the EGR pipeline and A catalyst connected to an exhaust manifold of the gas inlet for introducing a part of the exhaust gas into the EGR pipe, and a catalyst located downstream of the inlet and disposed in the EGR pipe to purify the exhaust gas introduced from the inlet. Have

BRIEF DESCRIPTION OF THE DRAWINGS The front view which shows the EGR apparatus of the engine which concerns on one Embodiment of this invention.

2 is a perspective view showing an EGR device for an engine according to one embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

2: exhaust manifold 4: annular bracket (support member)

6 catalyst 7a lower EGR line

7b: upper side EGR line 9b: bellows (movable member)

10a: EGR gas inlet 10b: EGR gas outlet

11: downstream EGR passage

EMBODIMENT OF THE INVENTION Hereinafter, one Example of manufacture of the EGR apparatus of the engine which embodied this invention is described.

In this embodiment, the EGR device of the present invention is applied to a four-cylinder gasoline engine.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view showing an EGR device of an engine of this embodiment, and Fig. 2 is a perspective view similarly showing an EGR device, in which 1 is a cylinder head of an engine. An exhaust manifold 2 is fixed to the exhaust side of the cylinder head 1. The exhaust manifold 2 has an engine side mounting flange 2a fixed to the cylinder head 1 by bolts 3 and an exhaust pipe 2c which is provided for each cylinder and exhaust gas discharged from each cylinder flows through. And an exhaust side connecting flange 2b connected to an exhaust pipe (not shown), the exhaust pipe 2c having an upper end welded to the engine side mounting flange 2a, and a lower end welded to the exhaust side connecting flange 2b. It is fixed. In addition, each exhaust pipe 2c is aggregated 2 cylinders downstream. In addition, the exhaust pipe has a catalyst disposed under the floor at the bottom of the vehicle, and at the same time, a silencer is disposed downstream. In addition, in this embodiment, the proximity catalyst provided in the part adjacent to the exhaust manifold 2 of an exhaust pipe is not provided.

In the middle of one of the plurality of exhaust pipes 2c, an annular bracket 4 as a support member is fixed by bolts 5, so that the annular bracket 4 has a tubular catalyst 6 ) In the inner circumference. The catalyst 6 is not required to purify the entire exhaust gas, but only to remove the bond of the SOF powder mainly containing unburned fuel, oil, and the like as described later. Therefore, the type of catalyst to be retained is not limited to Pt (platina), Pd (palladium), Rh (rhodium) and the like used for a general oxidation catalyst, but a lower oxidation type catalyst, for example, HC trap or selective reduction type. The zeolite used for the NOx catalyst may be retained.

From the lower part of the catalyst 6, the lower EGR line 7a is installed in a downward direction, and the lower end 8a of the lower EGR line 7a is welded and fixed to one assembly portion of the exhaust pipe 2c. The connection point comprises the EGR gas introduction part 10a. Similarly, the upper EGR conduit 7b is continuously installed upward from the upper part of the catalyst 6, and the upper end 8b of the upper EGR conduit 7b is welded and fixed to one side of the engine side mounting flange 2a, This connection point comprises the EGR gas derivation part 10b. Thus, the EGR line 7 is comprised by the lower EGR line 7a and the upper EGR line 7b, and the catalyst 6 is arrange | positioned downstream from the EGR gas introduction part 10a in this EGR line 7. .

Here, the bellows 9b as a movable member in which the metal pipe is processed into a corrugated box shape is installed in the upper EGR pipe line 7b, and the inner diameter of the annular bracket 4 is set slightly larger than the outer diameter of the catalyst 6, Since the catalyst 6 is allowed to move relative to each other, even if the exhaust manifold 2 is thermally expanded and the position of the catalyst 6 is displaced, the catalyst 6 is held by the annular bracket 4. It is.

In addition, the lower EGR line 7a is configured to be as short as possible, and as a result, as is apparent from FIG. 1, the catalyst 6 is located near the assembly portion of the exhaust manifold 2, that is, a dead space that has not been used conventionally. In addition, since it is arrange | positioned near and to the EGR gas introduction part 10a, the EGR gas with high temperature immediately after introduction is introduce | transduced inside.

On the other hand, as shown by the broken line in FIG. 2, the downstream side EGR passage 11 corresponds to the opening side of the upper EGR line 7b formed in the said engine side mounting flange 2a on the exhaust side side of the cylinder head 1 One end of is open. The downstream EGR passage 11 is disposed in the engine through the cylinder head 1, and the other end is opened on the intake side of the cylinder head 1, and the intake of the engine is via an EGR valve (not shown). It is connected to the passage.

In the EGR device configured as described above, the exhaust gas discharged according to the operation of the engine is discharged from the exhaust manifold 2 to the outside through the bottom catalyst and the silencer disposed in the exhaust pipe and the exhaust pipe. On the other hand, a part of the exhaust gas is introduced into the lower EGR pipeline 7a from the EGR gas introduction section 10a connected to the assembly portion of the exhaust manifold 2 as the EGR gas, so that the catalyst 6 and the upper EGR pipeline 7b. Then, it is returned to the intake passage side through the downstream EGR passage 11 and the EGR valve, and the reflux amount at this time is adjusted in accordance with the opening degree of the EGR valve to reduce the NOx emissions from the engine.

The EGR gas when passing through the catalyst 6 is removed by the action of the kind of catalyst to remove the SOF component and refluxed in the intake passage. This prevents deposition of deposits on the members constituting the intake system, for example, a throttle valve, an intake valve, or the like. As described above, since the catalyst 6 disposed in the EGR line 7 near the EGR gas introduction portion 10a is rapidly heated up by the high temperature EGR gas, SOF powder can be quickly removed even during cold start. Can be.

And since the EGR gas exclusive catalyst 6 is arrange | positioned in the EGR line 7 connected to the exhaust manifold 2 in this way, it does not affect the installation state to the exhaust pipe of the original exhaust gas purification catalyst, The SOF component in the EGR gas can be removed. Specifically, even when no exhaust catalyst is provided on the exhaust manifold side of the exhaust pipe as in the present embodiment, the EGR gas does not need to be refluxed from the downstream side of the catalyst below the floor separated from the engine. The manufacturing cost can be reduced by eliminating the need for a pipe line and accompanying seams such as bellows and spherical seams.

In addition, since the amount of EGR gas flowing through the catalyst 6 is particularly small compared to the total amount of exhaust gas, the catalyst 6 itself can be downsized, and the EGR is mainly carried out in the catalyst 6 in the low-mid load region. Since the EGR gas to be distributed does not reach very high temperatures, the catalyst 6 has a relatively margin against thermal deterioration. Therefore, the catalyst 6 can be manufactured at low cost, and the influence on the production cost due to the addition of the catalyst 6 is slight, and the overall cost reduction can be sufficiently achieved. Moreover, since the catalyst 6 is arrange | positioned in the dead space as mentioned above, the influence on the peripheral apparatus by addition of the catalyst 6 is also small, and it can carry out without reducing space efficiency in an engine room.

In addition, since the ERR pipeline 7 and the catalyst 6 are integrally formed with respect to the exhaust manifold 2 as described above, these members including the exhaust manifold 2 are connected to the engine in the engine assembly process step. It can be installed. That is, as described in Japanese Patent Application Laid-Open No. 2000-249003, when connecting the catalyst under the floor with the EGR line, the EGR line cannot be installed at the engine assembly step, so that the assembled engine is placed on the vehicle body. The EGR pipeline can be installed only at the stage of mounting, and mounting work becomes complicated. Therefore, according to the EGR apparatus of this embodiment, the advantage that the mounting work can be rationalized is also acquired.

On the other hand, as is well known, since the exhaust pipe 2c of the exhaust manifold 2 expands with exhaust heat for every engine operation, the distance between the upper and lower ends 8a and 8b of the EGR pipeline 7 fluctuates, or the upper and lower ends 8a. 8b is angularly changed in the circumferential direction (twisting direction), but the bellows 9a absorbs the thermal expansion, and the catalyst 6 moves in the axial direction with respect to the annular bracket 4 so that the heat Since the catalyst 6 can be supported without being affected by expansion, damage to the catalyst 6 due to the stress at this time can be prevented in advance, and furthermore, durability can be improved.

Although the description of the embodiment is finished as above, the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the embodiment is embodied in an EGR device for a four-cylinder gasoline engine. However, the type of the engine is not limited thereto, and the number of engine cylinders may be changed or may be embodied in an EGR device for a diesel engine. In addition, the presence or absence of the proximity catalyst is not limited, and may be applied to an engine provided with the proximity catalyst. Even in this case, advantages such as rationalization of the mounting operation can be obtained.

In the above embodiment, the engine side mounting flange of the EGR pipeline 7 is integrated with the engine side mounting flange 2a of the exhaust manifold 2, but a dedicated engine side mounting flange for the EGR pipeline 7 is provided. The exhaust manifold 2 may be provided separately from the engine side mounting flange 2a. Moreover, the EGR pipeline 7 is not limited to being connected to the downstream EGR passage 11 disposed in the cylinder head 1 but may be connected to the EGR passage provided outside the cylinder head 1. The EGR passage may be omitted, and the EGR gas may be refluxed from the EGR pipeline to the intake passage. In this case, the EGR valve is arranged in the EGR pipeline in the EGR pipeline.

Furthermore, in the above embodiment, the inner diameter of the annular bracket 4 is increased with respect to the outer diameter of the catalyst 6 to allow movement of the catalyst 6 in the axial direction, but the structure is not limited, For example, the annular bracket 4 keeps the catalyst 6 incapable of movement, while swinging the annular bracket 4 around the fixing bolt 5 to allow axial movement of the catalyst 6. Alternatively, the catalyst 6 may be allowed to move by the bending of the annular bracket 4 itself.

As described above, according to the EGR apparatus of the engine of the present invention, while the exhaust gas from the engine is discharged to the outside through the exhaust manifold and the exhaust passage, a part of the exhaust gas passes through the EGR line from the exhaust manifold as the EGR gas. It is returned to the intake system of the engine, and reduction of NOx emission is aimed at. On the other hand, the EGR gas is purified by a catalyst disposed in the EGR pipeline to remove the SOF powder, thereby preventing depositing deposits on each member constituting the intake system.

In this way, the EGR pipe is connected to the exhaust manifold so that it is not necessary to reflux the EGR gas from the downstream side of the catalyst separated from the engine, so that the long EGR pipe and the bellows and spherical seams accompanying it, etc. No costly joints are required, reducing manufacturing costs. In addition, the SOF component in the EGR gas is removed by the EGR gas exclusive catalyst disposed in the EGR pipeline.

In addition, since the amount of EGR gas flowing through the catalyst is particularly small compared to the total exhaust gas flow rate, the catalyst itself can be downsized, while the EGR gas is relatively low in temperature compared to the entire exhaust gas, and high heat resistance is not required for the catalyst. Inexpensive catalyst types can be used, and as a result, sufficient action can be obtained with inexpensive catalysts.

Therefore, irrespective of the installation state of the catalyst in the exhaust system, the EGR gas from which the SOF component has been removed can be refluxed without requiring the extension of the EGR pipe or the installation of a free joint, and as a result, the intake air can be reduced while Deposits of deposits in the system can be prevented.

In addition, the EGR pipe line has a lead-out portion for leading exhaust gas purified by a catalyst to an EGR passage arranged in the engine, and the lead-out flange has an engine-side mounting flange which is installed in the engine. By installing in the engine, the EGR device can be installed in the engine at the engine assembly step, and the mounting work can be rationalized.

Furthermore, by integrally configuring the engine side mounting flange of the EGR pipeline with the mounting portion of the exhaust manifold to the engine, these members including the exhaust manifold can be installed in the engine in the engine assembly process step, thereby further streamlining the mounting work. It becomes possible.

Further, by arranging the catalyst near the EGR gas introduction portion of the EGR pipe, the catalyst is rapidly heated by introducing an EGR gas having a high temperature immediately after the introduction, and rapidly removing SOF powder even at the time of cold start, and thus, the intake system. Deposition can be prevented more reliably.

In addition, since the EGR gas introduction portion is connected to the assembly portion of the exhaust manifold, the catalyst is disposed in the vicinity of the assembly portion of the exhaust manifold, that is, the dead space that has not been used conventionally, so that the influence on the peripheral equipment by the addition of the catalyst There is no, and EGR can be performed without reducing space efficiency in an engine room.

In addition, since the EGR pipeline has a movable member that can be stretched in the axial direction or movable in the circumferential direction, even if the exhaust manifold is thermally expanded, the thermal expansion is absorbed by the expansion or contraction in the axial direction of the movable member. In this case, catalyst damage due to stress at this time is prevented in advance, and the durability thereof can be improved.

In addition, since the catalyst is supported by the exhaust manifold via a support member that allows relative movement, the exhaust manifold is supported by the support member even if the exhaust manifold is thermally expanded and the position of the catalyst is displaced. Damage to the catalyst due to the resulting stress is prevented in advance.

Claims (7)

In the EGR apparatus of the engine for recirculating a part of the exhaust gas discharged from the engine to the intake air system through the EGR pipeline, An introduction portion 10a installed at one end of the EGR line 7 and connected to an exhaust manifold 2 of the engine, for introducing a part of the exhaust gas into the EGR line; An ERG apparatus for an engine, which is disposed downstream of the inlet and disposed in the EGR pipeline, and includes a catalyst (6) for purifying exhaust gas introduced in the inlet. 2. The EGR conduit according to claim 1, further comprising an induction part 100b which directs the exhaust gas purified by the catalyst to the EGR passage 11 disposed in the engine. The derivation unit of the engine has an engine side mounting flange (2a) installed in the engine. The exhaust manifold of claim 2, wherein the exhaust manifold has a mounting portion installed in the engine. The engine side mounting flange of the EGR pipeline is integrally formed with the mounting portion of the exhaust manifold. The engine EGR apparatus according to claim 1, wherein the catalyst is disposed near the introduction portion of the EGR pipeline. 2. The exhaust manifold according to claim 1, wherein the exhaust manifold is formed by aggregating a plurality of exhaust pipes 2c, And the introduction portion is connected to an assembly portion of the exhaust manifold. The engine EGR apparatus according to claim 1, wherein the EGR pipe line has a movable member (9b) that is expandable in the axial direction or rotatable in the circumferential direction. 2. An engine EGR apparatus according to claim 1, wherein the catalyst is supported by the exhaust manifold with support members (4, 5) interposed therebetween.