JP2001182626A - Exhaust gas recirculation system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation system of an internal combustion engine which recirculates EGR gas to an intake air passage after lowering its temperature and also enhances EGR gas distribution to each cylinder. SOLUTION: EGR gas and a part of intake air are introduced into an exhaust gas recirculation control valve 4 via an exhaust gas recirculation passage 6 and via a branch intake passage 5, respectively, and the part of intake air and the EGR gas are introduced into an intake air collecting part 1a of an intake manifold 1 simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation system for recirculating a part of exhaust gas to an intake system of an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, an internal combustion engine that performs an exhaust gas recirculation (referred to as EGR) in which a part of exhaust gas is taken out from an exhaust passage and recirculated to an intake passage for recirculation. Exhaust gas recirculation gas (EG
R gas) is a very high temperature and contains an inert gas for combustion. Therefore, when EGR is performed in the intake passage, the heat resistance of the portion where the EGR gas is introduced and the distribution to the cylinders of the internal combustion engine are improved. Care must be taken. Conventionally, EGR gas is introduced into the intake manifold, which is considered to be less likely to have heat resistance because it is made of metal such as aluminum, and is considered to have good distribution to each cylinder due to the collection of intake air. I was seen.

Further, in order to improve the output performance of the internal combustion engine, efforts have been made to further increase the filling rate of intake air into each cylinder of the internal combustion engine. It is one of the effective means to achieve. For example, there is a case in which heat transfer from a heat source (in this case, a cylinder head) to the intake passage is prevented by using a heat insulating gasket or the like. It is increasing.

On the other hand, there is an increasing demand for replacing an intake manifold made of metal such as aluminum with a resin material for the purpose of reducing cost, reducing mass, and improving the above-mentioned heat insulating properties. However, E having a higher temperature than the melting point of the resin material
In order to introduce the GR gas into the resin component, a method of introducing the GR gas needs to be devised, and various proposals have been made along with means for uniformly distributing the EGR gas to each cylinder of the internal combustion engine.

[0005] For example, as disclosed in Japanese Utility Model Laid-Open No. 59-159767 (hereinafter referred to as prior art 1),
Some pipes for introducing the GR gas are arranged inside the intake manifold of the intake manifold to promote the mixing of the intake air and the EGR gas and to distribute the mixture to each cylinder.

[0006] Alternatively, as disclosed in JP-A-9-317579 (hereinafter referred to as prior art 2),
It has been proposed that a GR gas inlet is provided for each intake port of an intake manifold communicating with each cylinder.

Further, as disclosed in JP-A-8-21316 (hereinafter referred to as prior art 3), a heat dissipating member is provided at the EGR gas introducing portion, and a heat insulating member is further provided between the EGR gas introducing portion and the intake manifold. In this case, the heat transfer from the EGR gas and the EGR gas inlet to the intake manifold can be prevented.

[0008]

However, the prior art 1
In the case of, when the capacity of the intake collecting section can be sufficiently secured, or when the operation area of the internal combustion engine has a large intake air amount,
Since it is considered that the mixing of the EGR gas and the intake air in the intake collecting section is successful, the EGR gas is expected to be equally distributed to each cylinder. However, in other cases, especially in the case of a small-displacement internal combustion engine for a small vehicle in which the capacity of the intake manifold cannot be increased so much due to mounting space and responsiveness, the EGR gas and the intake air are mixed. It is anticipated that it will not be possible to secure sufficient intake manifold capacity for
There is a possibility that the distribution of the GR gas may become uneven.

In the prior art 2, since the EGR gas introduction section is provided for each intake port communicating from the intake manifold to each cylinder, it is considered that the distribution is good, but the shape of the EGR gas introduction section becomes complicated. Therefore, there is a problem that the cost is increased, and a space for mounting and a mounting seat are required, so that a constraint condition on the intake manifold is increased, and the degree of freedom of the shape of the intake manifold is relatively reduced. Was.

In the prior art 3, the heat of the EGR gas itself and the heat conducted from the EGR gas to the EGR gas introduction section are released by using the heat radiating section, or a heat insulating material is provided between the EGR gas introduction section and the mounting section. By stopping the heat conduction itself by using the EGR gas, the heat conduction from the EGR gas to the intake manifold is prevented. However, it is necessary to enlarge the heat radiating part in order to sufficiently dissipate heat.As a result, the seat for attaching the heat radiating part to the intake manifold becomes very large, so the degree of freedom of the shape of the intake manifold is limited. Will decrease. In addition, E
The heat insulating material used for the attachment part of the GR gas introduction part is very expensive, and there is a problem that the cost increases.

Further, in these conventional techniques, high temperature E
Since the GR gas is directly introduced into the intake manifold and the intake manifold, the temperature of the intake air increases and the EGR
There is a possibility that the mounting portion of the gas introduction portion or the inner wall surface of the intake port portion directly hit by the introduced EGR gas may be exposed to a high temperature, which has been a major problem in promoting the replacement of the material of the intake manifold.

The present invention solves the above-mentioned problems of the prior art, and can reduce the temperature of the EGR gas to recirculate it to the intake passage and improve the distribution of the EGR gas to each cylinder. It is intended to provide an exhaust gas recirculation device for an internal combustion engine that can be used.

[0013]

In order to solve the above-mentioned problems, a means taken in the first aspect of the present invention is a main intake passage communicating with each cylinder of the internal combustion engine via a throttle valve and an intake manifold, and an exhaust gas. An exhaust recirculation passage that is branched from the passage and communicates with a portion of the main intake passage downstream of the throttle valve to recirculate part of the exhaust gas of the internal combustion engine to the main intake passage; An exhaust gas recirculation device for an internal combustion engine, comprising: an exhaust gas recirculation control valve for controlling an amount of exhaust gas recirculated to the main intake passage. An intake branch passage that is branched and communicates with the exhaust gas recirculation control valve is provided, and a part of exhaust gas and a part of intake air from the intake gas recirculation passage pass through the exhaust gas recirculation control valve and the exhaust gas. Via the flow passage is that so as to reflux in the main intake passage.

According to the above means, the EGR gas can be cooled by a part of the low-temperature intake air guided into the exhaust gas recirculation control valve by the intake branch passage.
Further, when the EGR gas is recirculated to the main intake passage, it can be simultaneously recirculated from the same position as the intake air from the intake passage, so that the mixing of the EGR gas and the intake air is promoted, and the EGR gas is supplied to each cylinder. The distribution property can be improved.

Here, a mixing chamber for mixing a part of the intake air and the EGR gas is provided in the exhaust gas recirculation control valve, and a part of the intake air generated in the mixing chamber is mixed with the EGR gas. It is desirable to recirculate the mixed gas to the main intake passage because the effect is further increased.

In the above means, it is preferable that the main intake passage is formed of a resin material.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exhaust gas recirculation system for an internal combustion engine according to the present invention will be described with reference to the drawings.

In FIG. 1, the main intake passage includes an intake manifold 1, a throttle body 2, and an air connector 3.
And supplies intake air to each cylinder (not shown) of the internal combustion engine. The intake manifold 1 is made of a resin material and has, at one end, intake port portions 1b, 1c, 1d, and 1e connected to intake ports of respective cylinders of a cylinder head (not shown) of the internal combustion engine, and at the other end. It has an intake manifold 1a. The air connector 3 has one end connected to an air cleaner (not shown) and the other end connected to the intake manifold 1 a of the intake manifold 1 via the throttle body 2. The throttle body 2 is provided with a throttle valve 2a for controlling the amount of intake air.

Intake manifold 1 of intake manifold 1
The exhaust manifold of the internal combustion engine (exhaust passage;
(Not shown) and exhaust recirculation passages 6 and 7 for recirculating a part of the exhaust gas (EGR gas) to the intake manifold 1a.
Is connected. An exhaust gas recirculation control valve 4 shown in FIG. 2 is interposed between the exhaust gas recirculation passages 6 and 7.

In FIG. 2, an exhaust gas recirculation control valve 4 communicates with a first input port 411 which communicates with an exhaust gas recirculation passage 6, a second input port 412 which communicates with a branch intake passage 5 described later, and an exhaust gas recirculation passage 7. Valves 415 a and 415 for opening and closing the communication between the first input port 411 and the output port 413 and the communication between the second input port 412 and the output port 413.
b, a cover 416 fixed to the housing 41, and the like. Inside the cover 416, as is well known,
The diaphragm 417 defines a transformation chamber and an atmosphere chamber. The variable pressure chamber can be selectively connected to the atmosphere or a vacuum tank (not shown) via a switching valve (not shown), and the atmosphere chamber is always in communication with the atmosphere. A shaft 414 having valves 415a and 415b provided at the distal end thereof is fixed to the diaphragm 417 so as to penetrate the housing 41 slidably in an airtight manner. The diaphragm 417 and the shaft 414 are connected to the variable pressure chamber by a valve portion 415a.
A spring 418 that constantly urges the valve closing side of the valve 415b is disposed, so that when the negative pressure is not supplied to the variable pressure chamber from a vacuum tank (not shown) via a switching valve (not shown), the valve portions 415a and 415b The valve is closed. The exhaust gas recirculation control valve 4 having the above-described configuration controls the supply of the negative pressure to the variable pressure chamber by a switching valve (not shown) according to the operating state of the internal combustion engine.
11 and the output port 413 and the second input port 41
2 and the output port 413 are opened and closed.

In the present embodiment, a mixing chamber 4a which is always in communication with the output port 413 in the housing 41 and is selectively in communication with the first and second input ports 411, 412 via the valve portions 415a, 415b. Is formed.

The second part of the housing 41 of the exhaust gas recirculation control valve 4
A branch intake passage 5 branched from the air connector 3 is connected to the input port 412. The branch intake passage 5 is provided with a check valve 5a that allows the fluid to flow to the second input port 412 but prevents the fluid from flowing from the second input port 412 to the air connector 3.

In this embodiment configured as described above, during operation of the internal combustion engine, the intake air is introduced into the intake manifold 1a via the air cleaner, the air connector 3, and the throttle body 2 (not shown), and Port 1b, 1
It is guided to each combustion chamber (not shown) through c, 1d and 1e.

At this time, according to the operating state of the internal combustion engine,
As described above, when the negative pressure is applied to the variable pressure chamber of the exhaust gas recirculation control valve 4, the valve portions 415 a and 415 b move between the first input port 411 and the output port 413 and the second output port 4.
The communication between the port 12 and the output port 413 is released. Thus, the EGR gas is introduced from the exhaust gas recirculation passage 6 into the mixing chamber 4a, and a part of the intake air is introduced from the intake branch passage 5 into the mixing chamber 4a. A part of the EGR gas and the intake air introduced into the mixing chamber 4a is mixed and becomes a mixed gas, and is introduced into the intake air collecting portion 1a via the exhaust gas recirculation passage 7. The mixed gas introduced into the intake manifold 1a is further mixed with the intake air from the main intake passage in the intake manifold 1a.

As described above, in the present embodiment, the EG
Since the R gas is preliminarily mixed with a part of the intake air from the branch intake passage 5 in the mixing chamber 4a, the R gas is effectively cooled to a temperature lower than the heat resistant temperature of the resin intake manifold 1.
It is not necessary to provide heat-resistant means when introducing the exhaust gas into the intake air collecting portion 1a, so that the configuration of the exhaust gas recirculation device can be simplified and the thermal load on the diaphragm and the like of the exhaust gas recirculation control valve 4 can be reduced. And durability can be improved. Further, since the EGR gas is preliminarily mixed with a part of the intake air in the mixing chamber 4a and further mixed in the intake air collecting portion 1a, the distribution of the EGR gas to each cylinder can be improved.

[0026]

According to the first aspect of the present invention, the heat from the EGR gas to a part of the intake gas is changed by the temperature difference between the part of the intake gas introduced into the exhaust gas recirculation control valve and the EGR gas. , The temperature of the EGR gas can be reduced.

Further, according to the present invention, since a part of the intake air and the EGR gas are simultaneously introduced into the main intake passage via the exhaust gas recirculation control valve, the mixing of the two is promoted, and the distribution is improved.

Further, since the heat conducted from the EGR gas to the exhaust gas recirculation control valve is also conducted to a part of the intake air introduced into the exhaust gas recirculation control valve, the temperature of the exhaust gas recirculation control valve itself is lowered, and the durability is improved.

According to the second aspect of the present invention, E
By mixing the GR gas with a part of the intake air, it is further mixed with the intake air when it is introduced into the intake manifold, which has the effect of further improving the distribution to each intake branch.

Further, by previously mixing the high-temperature EGR gas and a part of the low-temperature intake air, the temperature of the EGR gas introduced into the main intake passage can be further reduced.
Since the rise in the temperature of the intake air in the intake manifold is suppressed, the volume of the intake air is reduced, the filling rate of each cylinder of the internal combustion engine with the intake air is increased, and the output performance of the internal combustion engine can be improved.

As the temperature of the EGR gas further decreases, E
EGR gas can be introduced into the main intake passage without any special components for releasing heat of the GR gas, and a great effect is achieved when the material of the main intake passage is replaced, particularly when the intake manifold is replaced with a resin material. I do.

In addition, the EGR gas has a large thermal effect on the diaphragm and the like of the exhaust gas recirculation control valve. However, the gas obtained by mixing the EGR gas and a part of the intake gas has a lower temperature than the EGR gas, so that the exhaust gas is recirculated. The durability of the control valve is improved,
This eliminates the need to use an expensive material having excellent heat resistance, which is advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an exhaust gas recirculation device for an internal combustion engine according to the present invention.

FIG. 2 is a sectional view of the exhaust gas recirculation control valve in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intake manifold (main intake passage) 1a Intake collecting part (main intake passage) 1b, 1c, 1d, 1e Intake port part 2 Throttle body 2a Throttle valve 3 Air connector (main intake passage) 4 Exhaust recirculation control valve 4a Mixing chamber 41 Housing 411 First input port 412 Second input port 413 Output port 414 Shaft 415a, 415b Valve 416 Cover 417 Diaphragm 418 Spring 5 Intake branch passage 5a Check valve 6,7 Exhaust recirculation passage

Claims (3)

[Claims] 1. A main intake passage communicating with each cylinder of an internal combustion engine via a throttle valve and an intake manifold, and a main intake passage which is branched from an exhaust passage and communicates with a downstream portion of the main intake passage from the throttle valve. An exhaust gas recirculation passage that recirculates a part of the exhaust gas of the engine to the main intake passage; and an exhaust gas recirculation control valve that is interposed in the exhaust gas recirculation passage and controls an amount of the exhaust gas that recirculates to the main intake passage. An exhaust gas recirculation device for an internal combustion engine, comprising: an intake branch passage branched from a portion of the main intake passage upstream of the throttle valve and communicated with the exhaust gas recirculation control valve; And a part of the intake air from the intake branch passage is recirculated to the main intake passage via the exhaust recirculation control valve and the exhaust recirculation passage. Gas and gas recirculation device. 2. A mixing chamber in which the intake branch passage and the exhaust recirculation path can communicate with each other is provided in the exhaust recirculation control valve, and a part of intake air and a part of exhaust gas are separated in the mixing chamber. The exhaust gas recirculation device for an internal combustion engine according to claim 1, wherein the mixed gas generated by mixing is recirculated to the main intake passage. 3. The exhaust gas recirculation system for an internal combustion engine according to claim 2, wherein said intake manifold is formed of a resin material.