JP2582966B2 - Exhaust gas recirculation system for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art There is an engine in which an intake manifold of an engine is formed of a synthetic resin to reduce the weight and improve productivity. However, an engine that recirculates a part of exhaust gas (EGR gas) to an intake system. When a resin-made intake manifold is used, it is necessary to take sufficient measures against the thermal effect of the resin-made intake manifold from high-temperature EGR gas.

[0003] As a countermeasure against this, conventionally, for example, Japanese Patent Publication No. 2-1
Japanese Patent No. 46521 discloses a method in which a high-temperature component such as an EGR gas control valve is attached to a resin intake manifold through an adapter made of a heat-resistant material. There has been a problem that it causes an increase and an increase in the number of assembling steps.

Japanese Patent Application Laid-Open No. 63-164554 discloses a cooling system in which a cooling medium is circulated in the vicinity of an exhaust gas recirculation path for guiding EGR gas to a resin intake manifold. EG by medium
There has been a problem that the R gas is excessively cooled and deposits and the like easily occur in the exhaust gas recirculation passage.

In view of the above, the present invention relates to an exhaust gas recirculation system for an internal combustion engine having a resin intake manifold.
It is an object of the present invention to take sufficient countermeasures against the thermal influence of the EGR gas.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an exhaust gas recirculation system for an internal combustion engine in which an exhaust gas recirculation pipe for guiding EGR gas from an exhaust pipe is mounted in a resin intake manifold. An outer tube is connected to the intake manifold, one end of the outer tube is connected to an exhaust gas recirculation pipe inside the intake manifold, and a thermally insulated air layer is opened between the exhaust gas recirculation pipe and the outer tube.

Further, in an exhaust gas recirculation device for an internal combustion engine in which an exhaust gas recirculation pipe for guiding EGR gas from an exhaust pipe is mounted in a resin intake manifold, a cylindrical outer tube penetrating the exhaust gas recirculation pipe is connected to the intake manifold. Then, one end of the outer tube is connected to the exhaust gas recirculation pipe outside the intake manifold, and the outer tube is formed with an intake introduction hole communicating with the intake pipe upstream of the throttle valve.
An adiabatic air layer through which intake air flows is formed between the exhaust gas recirculation pipe and the outer tube.

[0008]

In the process in which the EGR gas flows into the intake manifold through the exhaust gas recirculation pipe, the temperature of the exhaust gas recirculation pipe rises due to the heat transfer from the high-temperature EGR gas, and the heat of the exhaust gas recirculation pipe passes through the outer tube. It is transmitted to the resin manifold. Since the exhaust gas recirculation pipe and the outer tube are connected to the exhaust gas recirculation pipe at an end protruding into the intake manifold, the outer tube promotes heat radiation to the intake air flowing through the intake manifold, and the above EGR gas to the intake manifold. , The heat transfer path is increased, heat radiation to the outside air flowing through the adiabatic air layer is promoted, and the amount of heat transferred to the intake manifold can be reduced.

The outer tube is connected to an exhaust gas recirculation pipe at an end protruding outside the intake manifold, and communicates with the intake pipe upstream of the throttle valve. Is radiated to the intake air flowing through the intake manifold, and the amount of heat transmitted to the intake manifold can be reduced.

In any case, since the exhaust gas recirculation pipe is cooled by air, components contained in the EGR gas flowing in the exhaust gas recirculation pipe are not excessively cooled, and deposits and water droplets adhere to the exhaust gas recirculation pipe. Can be prevented.

[0011]

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

As shown in FIG. 1, the resin intake manifold 1 has four branch portions 2 communicating with the intake ports of the respective cylinders, and a collector portion (surge tank) 3 for collecting the respective branch portions 2. An exhaust gas recirculation pipe 4 that communicates with an exhaust pipe (not shown) and guides EGR gas, which is a part of the exhaust gas, is provided upstream of the collector unit 3. A throttle chamber (not shown) is connected to the upstream side of the collector section 3, and the intake air flowing into the collector section 3 from the throttle chamber is mixed with the exhaust gas recirculating gas flowing from the exhaust gas recirculation pipe 4 into the collector section 3, and the respective branch sections 2. Shunts to each cylinder via
The amount of nitrogen oxides discharged from the exhaust pipe to the outside is suppressed.

Exhaust gas recirculation pipe 4 for intake manifold 1
As shown in FIG. 2, the mounting portion is provided with a cylindrical outer tube 5 through which the exhaust gas recirculation pipe 4 penetrates, and provided with a flange 6 which is joined to the outer periphery of the outer tube 5 by welding. It is fastened to the intake manifold 1 via two bolts 7.

The intake manifold 1 has a pair of plugs 19.
Is embedded, and each bolt 7 passing through the boss portion 12 of the flange 6 is screwed into each plug 19, whereby the flange 6 is fastened to the intake manifold 1. A hole 22 is formed in the intake manifold 1 to allow the outer tube 5 to pass therethrough with a gap 20 therebetween, and an annular groove 23 that opens concentrically with the hole 22 is formed on a joint surface with the flange 6.

The exhaust gas recirculation pipe 4 and the outer tube 5 are provided with an annular bush 8 between the ends 4A, 5A protruding from the collector section 3, and are connected to each other by welding via the bush 8. Is done.

The outer tube 5 and the exhaust gas recirculation pipe 4 are arranged concentrically with each other, and a heat insulating air layer 9 is defined between the two.

The outer tube 5 has the other end 5B protruding outward from the flange 6 opened to the outside.
Outside air flows from B to the insulated air layer 9.

As shown in FIG. 3, a boss 11 for fitting the outer tube 5 is formed in the flange 6, and three through holes 13, 1 orthogonal to each other are formed around the boss 11.
4 and 15 are formed.
A cooling passage 18 through which a cooling medium circulates is formed through piping (not shown) in which the connectors 6 and 17 are fitted and connected to the connectors 16 and 17.

Next, the operation will be described.

While the EGR gas flows into the intake manifold 1 through the exhaust gas recirculation pipe 4, the temperature of the exhaust gas recirculation pipe 4 rises due to heat transfer from the high-temperature EGR gas.
The heat of the intake manifold 1 passes through the bush 8, the outer tube 5, and the flange 6 while bypassing the heat insulating air layer 9.
Conveyed to. Since the bush 8 is interposed between the end 4A of the exhaust gas recirculation pipe 4 protruding into the intake manifold 1 and the end 5A of the outer tube 5, the heat transfer path from the EGR gas to the intake manifold 1 is lengthened. As a result, heat is radiated to the outside air flowing through the heat insulating air layer 9, and the end 4 A of the exhaust gas recirculation pipe 4, the bush 8, and the outer tube 5
5A is exposed to the intake air flowing into the intake manifold 1, and heat radiation to the end 5A is promoted, so that the amount of heat transmitted to the intake manifold 1 can be reduced.

Further, the flange 6 promotes heat radiation to the cooling medium circulating in the cooling passage 18 formed therein,
The intake manifold 1 can be reliably prevented from being overheated.

Conversely, the heat transfer from the cooling medium circulating through the cooling passage 18 cools the flange 6, the outer tube 5, the bush 8, and the exhaust gas recirculation pipe 4. , The components contained in the EGR gas flowing through the exhaust gas recirculation pipe 4 are not excessively cooled, and deposits and water droplets can be prevented from adhering to the exhaust gas recirculation pipe 4. .

Next, another embodiment shown in FIG. 4 will be described.

A cylindrical outer tube 21 is provided through the exhaust gas recirculation pipe 4, and a flange 27 connected to the outer tube 21 is fastened to the intake manifold 1 via two bolts 7.

The outer tube 21 has an annular bush 22 interposed between an end 21 B projecting outward from the flange 27 and the outer peripheral surface of the exhaust gas recirculation pipe 4, and is connected to each other via the bush 22 by welding.

The outer tube 21 and the exhaust gas recirculation pipe 4 are arranged concentrically, and a heat insulating air layer 24 is defined between them. The other end 21A of the outer tube 21 protrudes and opens inside the intake manifold 1, and the end 4A of the exhaust introduction pipe 4 protrudes and opens from the end 21A of the outer tube 21.

As shown in FIG. 5, the outer tube 21
Is formed in the middle of the intake pipe, and the intake pipe 26 is communicated with the connector 25 fitted to the flange 27 to the upstream side of the throttle valve of the intake pipe through a pipe (not shown).

Next, the operation will be described.

[0029] The intake air bypassing the throttle valve is introduced into the intake manifold 1 through the adiabatic air layer 24 from the intake opening 26 opened in the outer tube 21, thereby ensuring the intake air amount at the time of idling.

In the process in which the EGR gas flows into the intake manifold 1 through the exhaust gas recirculation pipe 4, the temperature of the exhaust gas recirculation pipe 4 rises due to the heat transfer from the high-temperature EGR gas.
Heat of the bush 22, while bypassing the insulating air layer 24,
It is transmitted to the intake manifold 1 via the outer tube 21 and the flange 27. The heat of the exhaust gas recirculation pipe 4, the bush 22, and the outer tube 21 facing the heat insulating air layer 24 is taken away by the air flow flowing into the heat insulating air layer 24 from the air inlet hole 26 opened in the outer tube 21, and transmitted to the air intake manifold 1. The amount of heat required can be kept small. Further, the end portion 21A of the outer tube 21 is exposed to the intake air flowing into the intake manifold 1 via the throttle valve, and heat radiation to the intake air is promoted, so that the amount of heat transmitted to the intake manifold 1 can be reduced.

As described above, since the exhaust gas recirculation pipe 4 is cooled by the intake air, components contained in the EGR gas flowing through the exhaust gas recirculation pipe 4 are not excessively cooled, and deposits and water droplets are formed in the exhaust gas recirculation pipe 4. Can be prevented.

[0032]

As described above, according to the present invention, the cylindrical outer tube penetrating the exhaust gas recirculation pipe is connected to the resin intake manifold, and one end of the outer tube is connected to the exhaust gas recirculation pipe inside the intake manifold. Since an adiabatic air layer opened to the outside is formed between the exhaust gas recirculation pipe and the outer tube, the amount of heat transmitted to the resin intake manifold can be sufficiently reduced by promoting heat radiation from the outer tube to the outside air and the intake air. .

Further, a cylindrical outer tube passing through the exhaust gas recirculation pipe is connected to a resin intake manifold, one end of the outer tube is connected to the exhaust gas recirculation pipe outside the intake manifold, and the outer tube is connected to the outer tube upstream of the throttle valve. An intake air hole that communicates with the intake pipe is formed, and an adiabatic air layer through which the intake air flows is formed between the exhaust gas recirculation pipe and the outer tube, so that heat is radiated from the outer tube to the intake. The amount of heat transferred can be kept sufficiently small.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the same.

FIG. 3 is a sectional view taken along the line AA in FIG. 2;

FIG. 4 is a sectional view showing another embodiment.

FIG. 5 is a cross-sectional view along the line BB of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intake manifold 4 Exhaust gas recirculation pipe 5 Outer tube 9 Insulated air layer 21 Outer tube 24 Insulated air layer 26 Intake introduction hole

Claims (2)

(57) [Claims] 1. An exhaust gas recirculation device for an internal combustion engine, wherein an exhaust gas recirculation pipe for guiding EGR gas from an exhaust pipe is mounted in a resin-made intake manifold, and a cylindrical outer tube penetrating the exhaust gas recirculation pipe is connected to the intake manifold. And
An exhaust gas recirculation device for an internal combustion engine, wherein one end of an outer tube is connected to an exhaust gas recirculation pipe inside an intake manifold, and an adiabatic air layer opened to the outside is formed between the exhaust gas recirculation pipe and the outer tube. 2. An exhaust gas recirculation device for an internal combustion engine having an exhaust gas recirculation pipe for guiding EGR gas from an exhaust pipe in a resin-made intake manifold, wherein a cylindrical outer tube penetrating the exhaust gas recirculation pipe is connected to the intake manifold. And
One end of the outer tube is connected to the exhaust gas recirculation pipe outside the intake manifold, and the outer tube is formed with an air intake hole communicating with the intake pipe upstream of the throttle valve, so that the intake air flows between the exhaust gas recirculation pipe and the outer tube. An exhaust gas recirculation device for an internal combustion engine, wherein a heat insulating air layer is formed.