JPH10131812A - Exhaust gas recirculation(egr) device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the backflow of EGR gas and expedite the mixture of EGR gas and an intake air by opening the discharge port of EGR gas so as to spout in the same direction as an intake pipe exit along the circumference of the intake pipe exit in an intake chamber. SOLUTION: EGR device is constituted so that exhaust/intake manifolds 11, 3 are connected by EGR pipe 6 arranged EGR valve 7 and EGR gas is recalculated to the intake manifold 3, which is formed by the branch pipe 5 to respective cylinders and an intake chamber 4 for discounting and supplying the intake air to the branch pipe 5. An exhaust dispersion room 8 for spouting EGR gas while being filled is formed along the outer periphery of the intake pipe 2 of a part to which this intake chamber 4 is connected and EGR pipe 6 is connected thereto. The discharge port 9 of the exhaust dispersion room 8 is opened along the circumference of the intake air discharge port 2a of the inner surface of the intake chamber 4 and EGR gas is supplied in the intake chamber 4 along the flow of the intake air supplied in the intake chamber 4 from the intake pipe 2.

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 exhaust gas recirculation and exhaust gas recirculation (EGR) for reducing NOx in exhaust gas used in a diesel engine of an automobile or the like. And equalizing the mixed gas to supply the mixed gas to each cylinder of the engine.

[0002]

2. Description of the Related Art In exhaust gas measures for diesel engines, in order to reduce the amount of NOx emitted from exhaust gas,
It is known that EGR is effective, in which a part of the exhaust gas, which is an inert gas, is recirculated to the intake air to suppress the combustion temperature and suppress the generation of NOx, and is widely used.

In this EGR device, if the EGR rate, which is the mixture ratio of the EGR gas recirculated to the engine and the intake air (fresh air), varies among the cylinders of the engine, an efficient and appropriate EGR system is used. And not only the NOx reduction becomes insufficient, but also a decrease in engine output and deterioration in fuel economy. In the prior art, in a structure in which an intake pipe is attached to an intake manifold, an intake pipe 2 is provided in an intake chamber 4 so as to intersect a direction of a branch pipe 5 in an intake manifold 3 as shown in FIG. As shown in FIG. 5 (b), the intake pipe 2 is connected to the branch pipe 5 in the middle of the intake chamber 4 to supply intake air to each cylinder. There are types.

In these cases, the exhaust manifold 11 and the intake pipe 2 are connected by an EGR pipe 6 having an EGR valve 7, and the EGR pipe 6 makes the EGR pipe 6 orthogonal to the flow of intake air in the intake pipe 2. Mixing is performed by discharging gas. In this case, since a small amount of EGR gas is supplied to a large amount of intake air so as to be orthogonal, the supply of this EGR gas is locally and non-uniformly mixed, so that the EGR rate of each cylinder becomes non-uniform. .

That is, for example, in a B-type four-cylinder engine, there is an intake pipe outlet 2a between the cylinders # 2 and # 3 as shown in FIG. 6, and the EGR pipe 6 is connected from the direction # 1. In this case, since the flow rate of the EGR gas is smaller than the intake air amount of the intake air, the intake air pushes the EGR gas downward of the inlet, and the amount of the EGR gas increases in the cylinders # 1 and # 2. The high-concentration mixed gas is supplied, and the flow of the EGR gas is difficult to flow to the opposite side of the inlet due to the flow of the intake air. Therefore, the amount of the EGR gas decreases in the cylinders # 3 and # 4. A low concentration mixed gas will be supplied.

In order to prevent the EGR rate from becoming non-uniform in each cylinder as described above, the EGR rate of the EGR pipe 6 to the intake pipe 2 is reduced.
The R pipe connection 6a is separated from the EGR pipe outlet 2a as much as possible, and the intake air and the EGR gas are mixed in the intake pipe 2 therebetween.

[0007]

On the other hand, EGR generally supplies EGR gas to the intake side by utilizing the fact that the pressure on the exhaust side is higher than the pressure on the intake side. However, on the intake side, the intake pressure P4 in the intake chamber 4 pulsates as the intake valve opens and closes, and the intake pressure P2 in the intake pipe 2 connected to the intake valve also pulsates. , The exhaust pressure P6 is pulsating.

More specifically, as shown in FIG.
4, P2 and the pulsation of the exhaust pressure P6. In the intake chamber, the pulsation of the intake pressure P4 is small, so that it does not exceed the pulsation of the exhaust pressure P6. The pulsating portion of the intake pressure P2 in the intake pipe 2 having a small passage area is larger than the pulsating portion of the intake pressure P4 in the intake chamber 4 because the larger the larger, the larger the smaller the passage area.

That is, the intake pressure P4 in the intake chamber 4
The pulsation of the intake pressure P2 in the intake pipe 2 is remarkably greater than that in the intake chamber 4 because the pulsation is expanded and propagated into the intake pipe 2. The intake pressures P4, P4
The width of the pulsation 2 and the average intake air pressure P4m become large especially when a supercharger is provided. Accordingly, when the EGR pipe 6 is connected and piped to the intake pipe 2 as in the above-described prior art, the pulsation of the intake pressure P2 in the intake pipe 2 is large, and as shown by the hatched portion in FIG. In some cases, the pulsating portion of the intake pressure P2 temporarily exceeds the pulsating portion of the exhaust pressure P6. At this time, a reverse flow of the EGR gas occurs, so that sufficient intake and good EGR cannot be performed, and the engine output There is a problem that the fuel consumption and fuel consumption deteriorate.

In Japanese Utility Model Laid-Open No. 3-114564,
There has been proposed an exhaust gas recirculation device (EGR device) in which an EGR annular path is formed on the outer periphery of an intake pipe and a plurality of through holes are provided in a wall surface of an intake pipe collecting portion to uniformly mix EGR gas and intake air. However, even when a plurality of through-holes are provided in the wall of the intake pipe collecting portion, the EGR gas easily flows backward because the EGR gas is supplied to the intake pipe side where the pulsation of the intake pressure is large. The gas repeats the normal flow and the reverse flow even in this through hole portion, soot in the EGR gas adheres and accumulates in this narrow through hole portion and closes the through hole to remove E.
There is a problem that the passage of the GR gas is obstructed.

Further, in order to equalize the EGR rate to each cylinder while preventing the back flow of the EGR gas,
It is conceivable that a branch pipe is formed at the tip of the pipe 6 and inserted into the branch pipe 5 to each cylinder. However, providing the branch pipe in the EGR pipe 6 not only complicates the pipe, but also ,
There is a problem that the weight of the engine increases and the cost increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem.
While preventing the reverse flow of the R gas, promoting the mixing of the EGR gas and the intake air, suppressing the variation in the EGR rate of each cylinder of the engine, and allowing the exhaust gas to recirculate at an even EGR rate,
An object of the present invention is to provide an EGR device that efficiently reduces NOx in exhaust gas.

[0013]

An EGR device for achieving the above object is a diesel engine EGR device for recirculating a part of exhaust gas to an intake side, in which an intake pipe is connected to an intake chamber. An exhaust dispersion chamber is formed along the outer circumference of the intake pipe of the above, and EGR is provided in the exhaust dispersion chamber.
Connecting a pipe, and further opening the discharge port of the exhaust dispersion chamber along the periphery of the intake pipe outlet on the inner surface of the intake chamber;
The EGR gas is supplied along the flow of the intake air supplied into the intake chamber.

The discharge port is formed by an annular continuous opening, or the discharge port is formed by a plurality of holes.

[0015]

Embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1A and 1B, the EGR device of the diesel engine 1 connects an exhaust manifold 11 and an intake manifold 3 with an EGR pipe 6 provided with an EGR valve 7 for controlling a recirculation amount of EGR gas. The exhaust gas is connected to the intake manifold 3 and recirculated to the intake manifold 3.

The intake manifold 3 includes a branch pipe 5 for each cylinder and an intake chamber 4 for distributing and supplying intake air to the branch pipe 5. The intake pipe 2 is connected to the intake chamber 4. An exhaust dispersion chamber 8 is formed along the outer periphery of the intake pipe 2 at a portion thereof, and EGR is provided in the exhaust dispersion chamber 8.
Connect tube 6. Further, the discharge port 9 of the exhaust dispersion chamber 8 is opened around the intake pipe outlet 2 a on the inner surface of the intake chamber 4, and EGR gas is supplied along the flow of intake air supplied from the intake pipe 2 into the intake chamber 4. It is formed so as to be supplied into the suction chamber 4.

As shown in FIGS. 1 (c) and 1 (d), the discharge port 9 is preferably formed by an annular continuous opening so as to surround the intake pipe outlet 2a. As shown, a plurality of holes may be formed by arranging them in a ring shape. In short, by surrounding the outer circumference of the intake flow and discharging the EGR gas along the intake flow, the EGR gas is mixed with the intake air into the intake chamber 4 using the flow of the intake air,
It is good to be configured to be dispersed.

As described above, the EGR device according to the present invention
Since the EGR gas discharge port 9 is opened in the intake chamber 4 having a relatively small pressure fluctuation so as to be ejected in the same direction as the intake pipe outlet 2a, the influence of intake with large pulsation can be reduced by EG.
Since R gas is hard to receive, E
The GR gas does not flow backward. In particular, as shown in FIG. 2, the discharge port 9 is filled with the EGR gas in the exhaust gas distribution chamber 8 formed at the exhaust pipe outlet 2a on the outer periphery of the intake pipe 2.
Therefore, the EGR gas is supplied into the intake chamber 4 so as to surround the intake air in a passage independent of the intake air. Therefore, the EGR gas is mixed and introduced into the intake chamber 4 without being disturbed by the pressure fluctuation and flow of the intake air.
It can be supplied while being dispersed.

Therefore, the EGR gas flowing together with the intake air is sufficiently mixed, the variation in the EGR rate of the mixed gas supplied to each cylinder of the engine can be suppressed, and good EGR can be performed for each cylinder. In addition, since each cylinder has the same EGR rate, the output of each cylinder can be equalized. Further, the EGR rate is changed in accordance with the engine operating range. Therefore, in the engine operating range where the EGR rate is relatively high, the EGR gas amount is large and the flow velocity increases. Is further promoted, and the effect of making the EGR rate of each cylinder uniform is increased.

Next, another embodiment of the present invention will be described. One of them is that, as shown in FIG. 3 (a), the exhaust dispersion chamber 8 is formed so as to surround substantially half or more of the outer circumference of the intake pipe 2, and the discharge port 9 is formed at the outlet of the intake pipe at the inner surface of the intake chamber 4. This is an EGR device formed to open along substantially half the circumference of 2a. With such a configuration, even when the size of the exhaust gas distribution chamber 8 is reduced, a much better mixing effect of the EGR gas and the intake air than the conventional EGR device can be obtained.

The other is, as shown in FIG. 3 (b), provided with a conical exhaust dispersion chamber 8 inside the intake chamber 4. Thus, the arrangement of the exhaust dispersion chamber 8 is described. Does not necessarily need to be provided outside the intake chamber 4.
The remaining part may be provided inside the intake chamber 4.
Further, the shape of the exhaust dispersion chamber 8 is not limited to a cylindrical shape, and may be any shape as long as the EGR gas can easily flow.

Further, a guide plate for assisting the swirling of the EGR gas is provided in the exhaust gas
When the swirling flow is applied to the gas, the mixing of the EGR gas and the intake air can be further promoted. In order to further improve the effect, in order to prevent the EGR gas from locally flowing out only from a part of the discharge port 9, the passage cross-sectional area of the discharge port 9 is set to be smaller than that of the EGR pipe 2. Adjust. For example, the passage area of the discharge port 9 corresponding to the width of the intake pipe 2 on the side of the EGR gas inlet portion is set to be equal to or smaller than the passage cross-sectional area of the EGR pipe 2.
The EGR gas is caused to flow out of the entire discharge ports 9 in the exhaust dispersion chamber 8.

Preferably, the cross-sectional area of the passage after the EGR gas has flowed from the EGR pipe 2 into the exhaust gas distribution chamber 8 is reduced by the EGR.
By setting the passage cross-sectional area of the pipe 2 or more, the passage resistance of the EGR gas is prevented from increasing, and the EGR gas can easily flow through the entire exhaust dispersion chamber 8.

[0024]

The EGR device according to the present invention has a large pulsation since the discharge port of the EGR gas is opened into the intake chamber along the periphery of the intake pipe outlet so as to jet in the same direction as the intake pipe outlet. The EGR gas is not affected by the accompanying intake air, the backflow of the EGR gas can be prevented, and the EGR gas is supplied into the intake chamber so as to surround the intake air along the flow of the intake air from the intake pipe. Therefore, the mixing of the EGR gas and the intake air is promoted, the variation in the EGR rate of each cylinder of the engine can be suppressed, the exhaust gas can be recirculated at a substantially equal EGR rate, and the NOx in the exhaust gas can be efficiently reduced. .

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a partial configuration view of an engine in a partial sectional view, and FIG. 1B is a sectional view of an X part of an EGR gas passage in FIG. Enlarged view,
(C), (d) is a perspective view of the X part of the EGR gas passage of (a).

FIG. 2 shows an EG showing a second embodiment of the EGR of the present invention.
It is a perspective view of an R gas passage.

FIG. 3E shows another embodiment of the EGR of the present invention.
It is a perspective view of a GR gas passage, (a) is a case surrounding substantially half of the outer periphery of the intake pipe, and (b) is a case where the exhaust dispersion chamber is provided inside the intake chamber.

FIG. 4 is a diagram showing E for explaining the flow of EGR gas according to the present invention;
FIG. 3 is a schematic sectional view of a GR gas passage.

FIG. 5 is a partial configuration diagram of an engine showing a conventional EGR gas passage, in which (a) shows an A type and (b) shows a B type.

FIG. 6 is a schematic cross-sectional view of an EGR gas passage for explaining a flow of an EGR gas according to the related art.

FIG. 7 is a pressure / crank angle diagram showing a relationship between exhaust pressure and intake pressure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake pipe 2a ... Intake pipe outlet 3 ... Intake manifold 4 ... Intake chamber 5 ... Branch pipe 6 ... EGR
Pipe 7… EGR valve 8… Exhaust dispersion chamber 9… Discharge port 10… Cylinder head 11… Exhaust manifold 12… Rectifier plate

Claims (3)

[Claims] 1. An EGR device for a diesel engine that recirculates a part of exhaust gas to an intake side, wherein an exhaust distribution chamber is formed along an outer periphery of the intake pipe at a portion where the intake pipe is connected to the intake chamber, and the exhaust gas is formed. An EGR pipe is connected to the dispersion chamber, and further, the discharge port of the exhaust dispersion chamber is opened along the periphery of the intake pipe outlet on the inner surface of the intake chamber, and along the flow of intake air supplied into the intake chamber, EGR
An EGR device configured to supply gas. 2. The EGR device according to claim 1, wherein said discharge port comprises a continuous annular opening. 3. The discharge port comprises a plurality of holes.
An EGR device as described.