JP2003056413A - Egr device in engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR cooling device capable of sufficiently cooling EGR gas with a simple device. SOLUTION: In an engine wherein a part of exhaust gas is supplied to an intake side via an EGR passage 4, a peripheral circuit 6 is formed on the intake side along the inner peripheral wall of an EGR valve 2. One end of the circuit 6 is connected to the passage 4 communicating with an exhaust side, and the other end is made to communicate with an intake passage 8 in the EGR valve 2 via a valve element 9.

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 EGR device for reducing NOx in exhaust gas and suppressing black smoke in an engine.

[0002]

2. Description of the Related Art NOx contained in exhaust gas of an internal combustion engine such as a gasoline engine or a diesel engine
In order to reduce the emission of black smoke and suppress the generation of black smoke.
(Exhaust gas recirculation) is generally performed. This is because if the combustion temperature in the combustion chamber is too high, NOx is likely to be generated, and if it is too low, black smoke is likely to be generated. Therefore, part of the exhaust gas is supplied again to the combustion chamber to increase the combustion temperature. To control. That is, the combustion temperature is controlled in the combustion chamber both by suppressing the combustion reaction by mixing the exhaust gas to reduce the amount of oxygen and by lowering the combustion gas temperature due to the large heat capacity of CO2 itself contained in the exhaust gas. can do.

In an engine equipped with such an EGR device, if the temperature of EGR gas is too high, EGR
Since the gas density is low, there is a problem that the EGR gas cannot be efficiently supplied. Therefore, conventionally, the water-cooled EGR valve shown in FIGS. 3 and 4 has been proposed.

That is, in this conventional example, the intake pipe 50
EGR valve 5 between the intake manifold 51 and the intake manifold 51.
2 are arranged, and these are combined to form the intake passage 53. An EGR passage 54 that communicates with the exhaust side is connected to the EGR valve 52, and the EGR passage 54 communicates with an intake passage 53 inside the EGR valve 52 via a valve body 55 whose opening degree can be adjusted. Then, the EGR valve 52
A cooling water passage 56 is formed in the main body of the engine so that cooling water for the engine can flow.

In such a conventional device, the EGR gas guided through the EGR passage 54 flows into the intake passage 53 by opening the valve body 55, is mixed with the intake there and is supplied to the combustion chamber. . At this time, the EGR valve 52
Since the main body of the EGR valve is cooled by the cooling water in the cooling water passage 56, the EGR that is in contact with the inner peripheral wall of the main body of the EGR valve 52 while being mixed with the intake air in the intake passage 53.
The gas is cooled.

However, in this prior art, the EGR gas introduced into the intake passage 53 is the EGR valve 52.
Since there are relatively few opportunities to come into contact with the inner peripheral wall of the body part of the
Even if the main body of the R valve 52 is cooled by water, the cooling water for the engine is used. Therefore, the cooling water for the relatively thin engine cannot be expected to have a further cooling effect.

Therefore, in order to eliminate such a drawback, a technique as disclosed in Japanese Patent Laid-Open No. 8-291773 has been proposed. That is, according to the technique, a part of the EGR passage is formed in a zigzag shape, and the zigzag portion is arranged behind the radiator electric fan, and the EGR gas is effectively generated by the cooling air generated by the electric fan. It is cooled to.

[0008]

However, in this prior art, although a certain cooling effect can be expected, the entire EGR device becomes large and it is difficult to install it in the engine room in a limited space. However, it has a drawback that the cost becomes high.

Therefore, an object of the present invention is to provide an EGR cooling device capable of sufficiently cooling EGR gas with a simple device.

[0010]

In order to achieve the above object, in the invention according to claim 1, a part of exhaust gas is EG
In an engine configured to supply to the intake side through an R passage, a part of the EGR passage is cooled by intake air to the engine.

According to the present invention, since the intake air of a relatively low temperature is used for cooling, the EGR gas can be sufficiently cooled.

According to a second aspect of the present invention, in the first aspect of the invention, an EGR valve is arranged on the intake side, and a part of the EGR passage cooled by intake air of the engine is provided in the EGR valve. In the invention according to claim 3, which is formed by further forming it, a peripheral circuit is formed along the inner peripheral wall of the EGR valve, and one end of the peripheral circuit is communicated with the exhaust side. In addition to being connected to the EGR passage, the other end is connected to the intake passage in the EGR valve via a valve body.

According to these inventions, the change can be made only by changing the EGR valve, so that the EGR cooling device can be downsized.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional plan view showing an intake side pipe line equipped with an EGR valve according to this embodiment. One end of an intake manifold 1 connected to each intake port of an engine has an EGR An intake pipe 3 is connected via a valve 2, and these are combined to form an intake passage 8. The main body of the EGR valve 2 includes an intake pipe 3
And an inflow port 5 communicating with the EGR passage 4 is provided in the outer peripheral portion. In the inner peripheral wall of the main body of the EGR valve 2, a peripheral circuit 6 is formed along the inner peripheral surface of the main body of the EGR valve 2 in an embedded state. In the illustrated embodiment,
The peripheral circuit 6 is provided so as to make a complete circle along the inner peripheral surface of the EGR valve 2, and one end thereof is provided with the inflow port 5
Is opened to communicate with the exhaust side of the engine through the EGR passage 4, and the other end is communicated with the intake passage 8 in the EGR valve 2 through the open hole 7. A valve body 9 which can be properly seated is arranged in the open hole 7, and the opening / closing is controlled by an actuator 10.

The operation of this apparatus will be described below. When the engine is in the operating state, intake air is sent to each intake port of the engine through the intake passage 8. On the other hand, part of the exhaust gas is supplied to the EGR valve 2 via the EGR passage 4, enters the peripheral circuit 6 from the inflow port 5, and flows there through to the EGR valve.
The gas flows into the intake passage 8 from the open hole 7 of the valve body 9 which goes around the main body of the valve 2 almost once. The EGR gas flowing into the intake passage 8 is sent to the combustion chamber from each intake port of the engine through the intake manifold 1 while being mixed with intake air therein. At this time, the opening degree of the valve body 9 is adjusted by the actuator 10 according to the operating condition of the engine and the inflow amount of the EGR gas is controlled to optimally reduce NOx and prevent black smoke.

The EGR gas is supplied to the peripheral circuit 6
It receives a sufficient cooling action while flowing inside. That is, since the intake air flowing through the intake passage 8 is in a relatively low temperature state,
The body portion of the EGR valve 2 that comes into contact therewith is sufficiently cooled, and the E flowing through the peripheral circuit 6 provided in the body portion E
The GR gas is also sufficiently cooled while coming into contact with the inner wall of the peripheral circuit 6. Thus, the combustion temperature of the air-fuel mixture in the combustion chamber is lowered, the amount of NOx produced is reduced, and the occurrence of heat damage is prevented.

The above-described embodiment has the following effects. (1) The combustion temperature in the engine can be lowered, and thereby the amount of NOx generated can be reduced. (2) Since the EGR gas can be sufficiently cooled,
EGR gas can be efficiently supplied. (3) Since the EGR gas can be cooled by circulating around the main body of the EGR valve, the degree of freedom in the layout in the engine room is increased. (4) Since it can be dealt with only by changing the EGR valve, EG
The R cooling device can be downsized and the cost can be reduced.

The present invention is not limited to the above-mentioned embodiment, but can be carried out as follows. In the above-described embodiment, the circular circuit makes one round around the EGR valve main body, but the present invention is not limited to this, and the spiral circuit may make multiple rounds of one round or more. In the above description of the embodiment, the material such as the intake manifold is not mentioned, but the material is not limited to the metal material, and the resin material (for example, PA6 or PA66) is used.
May be applied. In this case, by cooling the EGR gas, it is possible to exert a secondary effect that adverse effects on the resin material can be prevented in advance. A heat exchange promoter such as fins may be provided on the inner peripheral surface of the EGR valve body or the inner peripheral surface of the peripheral circuit. ○ The EGR passage is formed in a pipe shape, and the EGR passage is arranged in a zigzag shape and arranged in the intake passage of the EGR valve body,
It may be possible to exchange heat. The pipe-shaped EGR passage may be spirally wound in contact with the outer peripheral surface of the intake passage to allow heat exchange. ○ If the intercooler is provided, the EGR gas can be further cooled.

[0020]

As described above, according to the present invention, E
Since the GR gas can be sufficiently cooled, the EGR gas can be efficiently supplied to the intake air.
Since it can be dealt with only by changing the R valve, the EGR cooling device can be downsized.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view showing an essential part of the present invention (a view taken along the line BB in FIG. 2).

FIG. 2 is a sectional side view showing a main part of the present invention (a view taken along the arrow AA in FIG. 1).

FIG. 3 is a cross-sectional plan view showing a conventional device.

FIG. 4 is a sectional side view showing a conventional device.

[Explanation of symbols]

1 intake manifold 2 EGR valve 3 intake pipe 4 EGR passage 6 circuits 8 Intake passage 9 valve body

Claims (3)

[Claims] 1. An EGR device for an engine, wherein a part of exhaust gas is supplied to an intake side through an EGR passage, and a part of the EGR passage is cooled by intake air to the engine. 2. An EGR valve is arranged on the intake side, and the EGR valve is cooled by intake air of an engine.
The EGR device for an engine according to claim 1, wherein a part of the GR passage is formed. 3. An EGR that forms a peripheral circuit along an inner peripheral wall of the EGR valve, and connects one end of the peripheral circuit to an exhaust side.
The EG is connected to the passage and the other end is connected via the valve body.
The EGR device for an engine according to claim 2, wherein the EGR device communicates with an intake passage in the R valve.