JP2000054915A - Egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR device capable of increasing EGR effect, while maintaining responsiveness of EGR, promoting mixing of EGR gas and intake air, uniformizing an EGR rate of cylinders and keeping combustion of all of the cylinders good. SOLUTION: An EGR device is constituted so that: a tip portion of an EGR pipe 6, which connects an exhaust passage 2 of an engine 1 with an intake passage 3, is inserted into and protruded to the intake passage 3; an opening portion at the tip of the EGR pipe 6 is disposed to face upstream of intake air; and a swirl generating portion 9 is provided near the opening portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR device for an engine used in an automobile or the like, and more particularly, to an EGR device capable of promoting the mixing of EGR gas and intake air to equalize the mixing ratio of EGR gas in each cylinder. It concerns the device.

[0002]

2. Description of the Related Art In an exhaust gas countermeasure for an engine such as a diesel engine, a part of the exhaust gas, which is an inert gas, is recirculated to an intake side in order to reduce the emission amount of NOx in the exhaust gas. It is known that EGR (exhaust gas recirculation) that suppresses NOx generation by suppressing the NOx is effective, and is widely used.

In these engines, as shown in FIG. 8, an EGR pipe 6 branched from an exhaust pipe (exhaust passage) such as an exhaust pipe 2 and an exhaust manifold 2a is connected to an intake system such as an intake pipe 3 and an intake manifold 3a. The EGR valve 4 connected to a pipe (intake passage) and provided in the EGR pipe 6 allows EGR to be performed.
The EGR is performed by adjusting the flow rate of the GR gas Ge and controlling the EGR rate to an appropriate value according to the operation state of the engine.

The EGR valve 4 is provided near the junction of the intake manifold 3a with the intake pipe in order to improve the response of the EGR. The distance to enter 1 s is set to be short.

If the mixture of the EGR gas and the intake air is poor,
EGR gas mixture ratio in each cylinder, that is, E
Since the GR rate becomes uneven, in a cylinder with a high EGR rate,
Insufficient combustion air deteriorates combustion, and in a cylinder with a low EGR rate, EGR becomes incomplete and NOx cannot be reduced. Therefore, E is efficiently maintained while maintaining a good combustion state.
The GR cannot be performed to reduce NOx.

For this reason, it is important to mix the EGR gas and the intake air over a short distance, and various measures have been taken at the portion where the EGR pipe 6 and the intake passages 3 and 3a merge.

As shown in FIGS. 8 and 9, the EGR pipe 6 is joined to the intake passages 3 and 3a by opening the EGR pipe 6 at the side of the intake manifold 3a or the intake pipe 3. As shown in FIG. The opening method and, as shown in FIG.
A downstream opening method has been adopted in which the pipe 6 is inserted into the intake pipe 3 and the distal end thereof is directed downstream of the intake Ai.

[0008]

However, in any of these systems, the EGR gas Ge and the intake air Ai have a difference in their original properties and a difference in density and a difference in viscosity due to a temperature difference. , The mixing property is very poor, and the EGR as schematically shown by arrows in FIGS.
There is a problem that the gas Ge and the intake air Ai are unequally supplied to each cylinder without being mixed.

For this purpose, in Japanese Patent Application Laid-Open No. Hei 8-165960, as shown in FIG. 11, the distal end of the EGR pipe 6 is inserted into the intake pipe 3, and the opening is provided so as to face the flow direction of the intake Ai. The portion 6a is opened toward the upstream side and the EGR
The gas Ge is ejected in a direction opposite to the flow of the intake air Ai, and EG
There has been proposed an EGR device that promotes mixing of R gas Ge and intake air Ai.

However, this upstream opening type EG
Also in the R pipe, as shown in FIG. 11, since the flow of the intake Ai flows relatively smoothly around the distal end portion of the EGR pipe 6, the flow of the EGR gas Ge flows while surrounding the flow of the intake Ai. As a result, the problem that mixing of both gases Ge and Ai becomes insufficient remains.

The opening 6a of the EGR pipe 6 is connected to the intake Ai.
Are arranged in a direction in which the EGR gas G flows.
Unless the pressure of e is higher than the pressure on the intake pipe 3 side, the EGR gas Ge cannot flow out, and there is a problem that the range in which EGR can be performed becomes narrow.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. It is an object of the present invention to promote the mixing of EGR gas and intake air while maintaining the EGR responsiveness. E that can equalize the EGR rate and increase the EGR effect while maintaining good combustion in all cylinders
It is to provide a GR device.

[0013]

According to an EGR device for achieving the above object, a tip of an EGR pipe connected from an exhaust passage of an engine to an intake passage is inserted and projected into the intake passage. An opening at the tip of the EGR pipe is disposed facing the upstream side of the intake air, and a vortex generator is provided near the opening.

[0014] The eddy current generating portion is formed by providing the EGR pipe with a cylindrical diameter changing portion whose tip end is reduced and whose diameter gradually increases along the flow direction of the intake air. When the EGR pipe is a circular pipe, the diameter changes. However, when the EGR pipe is an EGR pipe having another cross section, the outer diameter has a step and the cross-sectional area changes. It is the part that has. Also, EGR is provided on the outer periphery of the cylinder diameter changing portion.
A first outflow hole for the gas is provided, or a second outflow hole for the EGR gas is provided on a surface of the cylinder diameter change portion facing the intake flow.

Alternatively, the tip of an EGR pipe connected from the exhaust passage of the engine to the intake passage may be inserted and protruded into the intake passage, and the tip of the EGR pipe may be closed to distribute toward the upstream side of intake air. A third outflow hole for the EGR gas is provided on the outer peripheral portion of the EGR pipe, and a vortex generator is provided near the third outflow hole to constitute an EGR device.

In these EGR devices, the eddy current generating portion may be provided with a projection on the outer peripheral portion of the EGR tube, the eddy current generating portion may be provided with a ring member on the outer peripheral portion of the EGR tube, or The vortex generator is formed by providing a ring-shaped protrusion on the inner periphery of the intake passage.

According to the EGR devices having these configurations, the EG
A swirl flow is generated in the flow of the intake air by the swirl flow generating portion provided near the exit of the EGR gas in the R pipe, and the swirl flow sucks and mixes the EGR gas and efficiently mixes the EGR gas with the intake air.

Therefore, since the mixture is sufficiently mixed at a short distance, the mixed gas of the uniformly mixed EGR gas and the intake air is supplied to each cylinder, and the difference in the EGR rate between the cylinders is eliminated.
The effect of EGR is sufficiently exhibited while the combustion state is good in all cylinders. Therefore, the turbulent EGR gas can be introduced into the turbulent flow of the intake air by the generated eddy flow to promote the mixing while keeping the excellent EGR responsiveness by shortening the mixing distance.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

The EGR device according to the first embodiment of the present invention, as shown in FIGS. 1 to 3, has a structure in which an intake pipe 3 of an intake manifold (intake passage) 3a extends from an exhaust manifold (exhaust passage) 2a of an engine 1. The EGR pipe 6 is inserted in the vicinity of the connection part, and the tip of the EGR pipe 6 is made to protrude into the intake manifold 3a or the intake pipe 3, so that the opening 8 at the tip of the EGR pipe 6 is located upstream of the intake Ai. It is arranged facing.

Then, as shown in FIG. 1 or FIG. 2, the cylindrical diameter changing portion 91 acting as the vortex generator 9 in the EGR pipe 6 near the opening 8 is reduced at the tip end so that the flow direction of the intake air Ai is reduced. Are formed by overlapping cylinders having different diameters.

That is, the outer shape of the EGR pipe 6 is formed in a stepwise manner with respect to the flow direction of the intake air Ai, so that the intake air flow is changed not only in the axial flow direction but also in the radial direction to generate a vortex. I do.

In FIG. 1, the maximum diameter portion of the cylinder diameter changing portion 91 and the thickness of the rear EGR pipe 6 are the same.
In the figure, the rear side of the cylinder diameter changing portion 91 is narrowed, and the maximum diameter of the cylinder diameter changing portion 91 is formed to be larger than the rear EGR pipe 6.

The outflow hole 8a for letting out the EGR gas Ge is provided in addition to the opening 8 on the tip side of the cylindrical diameter changing portion 91, the outer peripheral side of the cylindrical diameter changing portion 91 or the outflow hole 8b.
Is provided on the surface of the cylinder diameter changing portion 91 facing the intake air flow, that is, on the disk portion of the cylinder diameter changing portion 91.

The opening 8 and the first outflow hole 8 in the outer peripheral portion are provided.
a and the second outflow hole 8b on the front surface may be only one of them, a combination of these two, or a combination of all three as shown in FIG. 1 and FIG. Good.

With the EGR device having the above configuration, the tip of the EGR pipe 6 is provided toward the upstream side of the intake air Ai of the intake pipe 3, and the tip of the EGR device is provided with a cylinder diameter changing portion 91 which is the vortex flow generating portion 9. Since the EGR gas Ge flows out from the opening 8 of the EGR pipe 6, the first outflow hole 8 a in the outer peripheral portion, and the second outflow hole 8 b in the front surface, as shown in FIG. The generated eddy current is sucked into the flow of the intake air Ai and mixed with the intake air Ai.

FIG. 3 shows the flow state of the upstream opening type EGR pipe 6 having the vortex generator 9 of the present invention, and FIG.
12 schematically shows the flow state in the case where the first outflow hole 8a is provided in the EGR pipe 6B of the upstream opening type, but in comparison, the EGR device of FIG. 3 is better than the EGR device of FIG. Many eddies are generated and mixing is promoted.

Therefore, the EGR device having the swirl generator 9 can efficiently mix the EGR gas Ge and the intake air Ai, so that the mixed gas of the EGR gas and the intake air uniformly mixed even in a short distance is supplied to each cylinder. Can supply.

As a result, the EGR rate among the cylinders can be equalized while maintaining good EGR responsiveness, so that the EGR effect can be enhanced while maintaining good combustion in all cylinders.

Further, the EGR according to the second embodiment of the present invention
The device is almost the same as the embodiment of FIGS.
As shown in FIG. 4, the third end provided on the outer peripheral portion of the EGR tube 6 is closed by closing the front end portion of the EGR tube 6 to eliminate the opening 8 at the front end.
The EGR gas Ge is formed to flow out only from the outflow hole 8c.

With this configuration, the intake air Ai
Does not flow, so that even if the exhaust pressure of the EGR gas Ge is low, EGR can be performed and the range in which EGR can be performed can be widened. Then, a vortex generator 9 is provided in the vicinity of the third outlet 8c to generate a vortex in the flow of the intake air Ai.

In FIG. 1 to FIG. 4, the vortex generator 9 includes
Although formed by the cylinder diameter changing portion 91, as shown in FIG. 5, it is also possible to form a large number of protrusions 94 on the outer peripheral portion of the EGR pipe 6. In FIG. 5, the first outlet hole 8a is configured to open the door, and the portion corresponding to the lid of the first outlet hole 8a is raised in the outer peripheral direction to form the projection 94. However, small pieces are attached by welding or the like. May be.

As shown in FIG. 6, an annular ring member 92 and a helical member 93 may be provided separately from the EGR tube 6, or may be in contact with the outer peripheral surface of the EGR tube 6. It may be wound in a state. Further, EGR
As shown in FIG. 7, not only the pipe 6 side but also the intake passages 3 and 3a
A ring-shaped protrusion 95 may be provided on the side, or the ring member 96 may be held in the intake passages 3 and 3a.

In short, the EGR gas Ge is supplied to the intake passages 3 and 3
a near the air including upstream and downstream flowing into
The surface of the pipe 6, the surface of the inner peripheral surface of the intake passages 3 and 3a, and the EGR
A portion that generates a vortex may be provided as a vortex generator 9 in the space between the pipe 6 and the intake passages 3 and 3a.

The vortex generator 9 normally generates a vortex by providing a linear step (a ring member 92 or the like) for generating a vortex in a sharp step portion or a downstream portion of the flow path. In addition to the shape change, the intake pipe connected to the external pipe is blown into the intake passages 3 and 3a in the circumferential direction to be merged, or the intake passages 3 and 3 are made using high-temperature EGR gas.
It can also be formed by providing a high-temperature portion locally in a.

With the EGR device having these configurations, the EGR
The distal end of the pipe 6 is inserted into and protruded into the intake passages 3 and 3a, and the opening 8 at the distal end of the EGR pipe 6 is disposed facing the upstream side of the intake air Ai to generate a vortex near the opening 8. Part 9
By providing a swirl generator 9 near the third outflow hole 8c provided in place of the opening 8, a swirl is generated in the intake flow to promote the mixing of the intake Ai and the EGR gas Ge. Can be done.

Therefore, the EGR gas Ge and the intake air Ai can be efficiently mixed even within a short mixing distance for improving the response of the EGR, so that the uniformly mixed gas mixture can be uniformly supplied to each cylinder. When the responsiveness of the EGR is kept high, the NOx reduction effect by the EGR can be improved while maintaining good combustion in all cylinders.

Further, instead of the opening 8 opened in the flow direction of the intake air Ai, a third outlet 8c opened to the side of the flow.
Is provided, the intake air Ai does not flow into the EGR pipe 6, and even if the exhaust pressure of the EGR gas Ge is small,
Since the pressure drop portion is formed by the intake flow, particularly by the vortex, the EGR gas Ge can be sucked and discharged. Therefore, the range in which EGR can be performed can be widened, and NOx by EGR can be increased in a wide operating range of the engine.
Reduction can be achieved. In addition, since the vortex generator 9 can be formed with a relatively simple structure as shown in FIGS.
The swirl generator 9 can be provided in the existing EGR pipe 6 by simple processing.

[0039]

As described above, according to the EGR device of the present invention, the vortex generator is provided near the EGR gas outlet of the EGR pipe, so that the EGR gas can be supplied while maintaining excellent EGR responsiveness. It can be introduced into the turbulence of the intake air to promote mixing.

In addition, the vortex generator is provided with an EGR pipe having a tip portion directed toward the upstream side of the intake air, and a tube diameter changing portion provided at the tip portion, so that the EGR pipe is formed from an outer peripheral portion of the EGR pipe and an outlet hole at the tip face.
Since the R gas is caused to flow out, a vortex is generated in the flow of the intake air at the cylinder diameter change portion, and the EGR gas is sucked and mixed by the eddy flow, so that the EGR gas and the intake air can be efficiently mixed.

As a result, a uniformly mixed gas of EGR gas and intake gas can be supplied to each cylinder, so that the difference in EGR rate between the cylinders can be eliminated, and EGR can be performed while maintaining good combustion in all cylinders. Can increase the NOx reduction effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an EGR device according to the present invention.

FIG. 2 is a perspective view of a distal end portion of an EGR pipe showing a vortex flow generating portion according to a cylinder diameter changing portion according to the present invention.

FIG. 3 is a partial sectional side view of an intake passage at a distal end portion of an EGR pipe schematically showing a state of mixing of intake gas and EGR gas in an EGR device according to the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the EGR device according to the present invention.

FIG. 5 is a diagram showing another embodiment of the eddy current generator.
(A) shows the eddy current generation part by a projection part, (b) is XX sectional drawing of (a).

FIG. 6 is a diagram showing another embodiment of the eddy current generator.
(A) shows the eddy current generation part by a ring member, (b) shows the eddy current generation part by a spiral member.

FIG. 7 is a view showing another embodiment of the eddy current generator.
(A) shows a vortex generating portion formed by a ring-shaped protrusion provided on the intake passage side, and (b) shows a vortex generating portion formed by a ring member provided from the intake passage side.

FIG. 8 is a configuration diagram showing an EGR device in which a prior art EGR valve is provided at an inlet of an intake manifold.

FIG. 9 is a configuration diagram showing a conventional EGR device of a side opening type of an EGR pipe.

FIG. 10 shows a prior art EGR of a downstream opening type of an EGR pipe.
It is a block diagram showing an apparatus.

FIG. 11 shows a prior art EGR of an upstream opening type EGR pipe.
FIG. 3 is a partial configuration diagram illustrating the device.

FIG. 12 is a partial configuration diagram showing an EGR device that is an upstream opening type of the EGR pipe and has a first outflow hole provided in the EGR pipe.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 1s Cylinder 2 Exhaust pipe 2a Exhaust manifold 3 Intake pipe 3a Intake manifold 4 EGR valve 6 EGR pipe 8 Opening 8a First outflow hole 8b Second outflow hole 8c Third outflow hole 9 Eddy flow generator 91 Tube diameter changing part 92 Ring member 93 Spiral member 94 Protrusion 95 Ring-shaped protrusion 96 Ring member

Claims (8)

[Claims] An end of an EGR pipe connected from an exhaust passage of an engine to an intake passage is inserted into and protruded into the intake passage, and an opening at the end of the EGR pipe faces upstream of intake air. An EGR device, wherein the EGR device is provided, and a vortex generator is provided near the opening. 2. The eddy current generating section is formed by providing a cylinder diameter changing section in which a distal end side is reduced in the EGR pipe and a diameter is gradually increased along a flow direction of intake air. 2. The EGR device according to 1. 3. The EGR device according to claim 1, wherein a first outflow hole for EGR gas is provided on an outer periphery of the cylinder diameter changing portion. 4. The EGR device according to claim 1, wherein a second outflow hole for the EGR gas is provided on a surface of the cylinder diameter changing portion facing the intake air flow. 5. An end of an EGR pipe connected to an intake passage from an exhaust passage of the engine is inserted into and protruded into the intake passage, and the end of the EGR pipe is closed to distribute toward an upstream side of intake air. An EGR device, wherein a third outflow hole for EGR gas is provided in an outer peripheral portion of the EGR pipe, and a vortex flow generating part is provided near the third outflow hole. 6. The eddy current generating part is formed by providing a projection on an outer peripheral part of the EGR pipe.
Or the EGR device according to 5. 7. The EGR device according to claim 1, wherein the eddy current generating portion is formed by providing a ring member on an outer peripheral portion of the EGR pipe. 8. The EGR device according to claim 1, wherein the vortex flow generating portion is formed by providing a ring-shaped protrusion on an inner peripheral portion of the intake passage.