JPH1077914A - Exhaust gas recirculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device which is capable of preventing back flow of exhaust gas to the side of an intake throttle valve at time of an EGR (exhaust gas recirculation) without hindering intake flow within an intake pipe when the EGR is suspended. SOLUTION: In an EGR device provided with an EGR pipe 3 for returning part of exhaust gas to an intake pipe 2 and an EGR valve 4 opening and closing the EGR pipe 3, a straightening vane 8 for backflow prevention projecting to the inside of the intake pipe 2 from the exit of the EGR pipe 3 and guiding exhaust gas toward the side of downstream of the intake pipe 2 at the time of opening the valve part 6b of the EGR valve 4 (at the time of an EGR) and withdrawing into the exit of the EGR pipe 3 and saving from the intake pipe 2 at the time of closing the valve part 6b (at the time of suspending the EGR) is provided at the valve part 6b of the EGR valve 4.

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 (hereinafter, referred to as EGR) device for extracting a part of exhaust gas from an exhaust system and returning the exhaust gas to an intake passage in an internal combustion engine.

[0002]

2. Description of the Related Art In the above-mentioned EGR device, in order to improve the mountability on a vehicle, an intake throttle valve for controlling an intake air amount and an EGR pipe provided downstream of the intake throttle valve are introduced into an intake pipe. EGR for controlling the amount of exhaust gas
It is desirable to arrange the valve as close as possible to achieve miniaturization. However, since part of the exhaust gas flowing from the EGR pipe tends to flow backward due to intake pulsation generated during operation of the engine, if the intake throttle valve and the EGR pipe are too close, they are contained in the exhaust gas. The deposit adheres to the outer peripheral portion of the valve portion of the intake throttle valve, causing a change in the flow rate characteristics of the intake throttle valve or a malfunction.

[0003] Therefore, in order to prevent the performance of the intake throttle valve from deteriorating due to the backflow of exhaust gas, for example, an actual throttle valve 4 is used.
Japanese Patent Application Laid-Open No. 58-28583 discloses a method in which the end of an EGR pipe is protruded into an intake pipe and an outlet is formed downstream.
A method has been proposed in which a flow straightening plate is provided at an outlet of an R pipe so as to guide exhaust gas to flow downstream.

[0004]

However, according to the conventional exhaust gas backflow prevention system described above, the effect of preventing exhaust gas backflow and preventing deposits from adhering to the intake throttle valve is sufficiently obtained. There is a problem in that the flow of intake air is obstructed by an EGR pipe or a straightening plate protruding into the intake pipe during an EGR stop such as during idling or high-load high-speed rotation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to prevent the intake air flow in the intake pipe from being obstructed when the EGR is stopped,
It is an object of the present invention to provide an EGR device capable of preventing exhaust gas from flowing back to the intake throttle valve at the time of GR.

[0006]

Means for Solving the Problems In order to solve the above problems, the present invention is configured as follows. That is, the invention of claim 1 is an exhaust gas recirculation system including an EGR passage for returning a part of the exhaust gas to an intake passage and an EGR valve for opening and closing the EGR passage.
When the valve is opened, it projects into the intake passage and the E
A rectifying member that guides exhaust gas flowing out of the GR passage toward the downstream side of the intake passage and retracts from the intake passage by closing the EGR valve is provided.

According to the first aspect of the present invention, when the EGR valve opens the EGR passage to return the exhaust gas to the intake passage, the rectifying member projects into the intake passage by the opening operation. By guiding the exhaust gas flowing from the EGR passage to the intake passage toward the downstream side of the intake passage, the exhaust gas is prevented from flowing back to the intake throttle valve side. On the other hand, at the time of EGR stop in which the EGR valve closes the EGR passage so as to stop the EGR, the closing operation retracts the rectifying member from the intake passage, thereby preventing the rectifying member from obstructing the flow of intake air in the intake passage.

In the case where the rectifying member projects or retracts into the intake passage in connection with the opening / closing operation of the EGR valve, the EG
Although it is possible to mechanically or electrically link the valve portion of the R valve and the rectifying member, as described in claim 2,
2. The exhaust gas recirculation device according to claim 1, wherein the rectifying member is formed in a valve portion of an EGR valve that opens and closes an outlet of the EGR passage, and enters and exits the outlet of the EGR passage by opening and closing the EGR valve. Is desirable.

With this configuration, the rectifying member projects from the EGR passage into the intake passage at the time of EGR to prevent the exhaust gas from flowing backward. Avoid interference. In this case, when the valve portion of the EGR valve and the rectifying member are integrally formed, the structure is such that the rectifying member is simply added to the valve portion, so that the production is easy and the structure is simplified.

[0010] Also, as described in claim 3, claim 1
In the exhaust gas recirculation device described in the above, it is preferable that a guide member for guiding the EGR gas guided by the rectifying member further downstream is provided in the intake passage. With such a configuration, the effect of preventing the backflow of EGR gas to the intake throttle valve side during EGR can be further enhanced.

[0011]

Embodiments of the present invention will be specifically described below with reference to the drawings. First, an exhaust gas circulation (hereinafter referred to as EG) according to the first embodiment will be described with reference to FIGS.
R) will be described. 1 and 2 are cross-sectional views of the EGR device. FIG. 1 shows a state where the EGR valve is opened.
FIG. 2 shows the state when the valve is closed. FIG. 3 is a sectional view taken along line AA of FIG. 1, and FIG. 4 is a perspective view showing a valve portion and a rectifying member of the EGR valve. In the drawing, reference numeral 1 denotes a butterfly type intake throttle valve provided in an intake pipe 2 serving as an intake passage. The amount of exhaust gas recirculation gas (hereinafter, referred to as EGR gas) flowing from an EGR pipe 3 having a circular cross section as an EGR passage provided on the downstream side is adjusted.

The intake pipe 2 is provided with an intake cooling type EGR valve 4. This intake cooling EGR valve 4
Is a poppet valve whose main body is provided on the opposite side of the EGR pipe 3 with respect to the intake pipe 2 and which is connected to the diaphragm 5.
Of the EGR pipe 3 at the outlet of the EGR pipe 3
The outlet of the EGR pipe 3 is opened and closed by abutting or separating from a. The opening and closing operation by the poppet valve 6 is controlled by the balance between the EGR negative pressure acting on the diaphragm 5 and the force of the spring 7.

Further, an EGR is provided on the tip end surface of the valve portion 6b.
A rectifying plate 8 is provided as a rectifying member for preventing backflow that guides the EGR gas flowing out of the pipe 3 into the intake pipe 2 to the downstream side of the intake pipe 2. As shown in FIG. 4, the current plate 8 is formed in a substantially semi-cylindrical shape corresponding to the inner diameter of the EGR pipe 3 and is provided upstream of the center of the valve portion 6b. When the valve is open, it projects into the vent pipe 2 as shown in FIG. 1, and when the valve is closed, E protrudes as shown in FIG.
By retracting to the outlet of the GR pipe 3, it is retracted from the inside of the ventilation pipe 2. In addition, the current plate 8 is formed to be slightly longer than the valve stroke of the poppet valve 6 so that it does not fall out of the EGR pipe 3 even in the state of the maximum opening.

A guide pipe 9 is fixed in the intake pipe 2 as a guide member for guiding the EGR gas guided downstream by the rectifying plate 8 further downstream.
The guide tube 9 is formed in a substantially U-shape with open front and rear ends in the flow direction so as not to obstruct the intake flow.
The upstream end is disposed so as to surround the downstream side of the center of the valve portion 6b and the downstream end of the current plate 8.

The EGR device according to the present embodiment is configured as described above, and when the EGR valve 4 is opened when the valve portion 6b of the EGR valve 4 is separated from the seat portion 3a of the EGR pipe 3, ie, when the EGR valve 4 is opened. At the time of EGR, as shown in FIG. 1, the current plate 8 projects from the outlet of the EGR pipe 3 into the intake pipe 2 and is arranged so as to close the upstream side of the EGR pipe 3. Therefore, in this state, the EGR gas flowing out of the EGR pipe 3 is guided downstream along the end surfaces of the flow straightening plate 8 and the valve portion 6b as shown by the arrow in the figure, and further guided downstream along the guide pipe 9. You. This prevents the EGR gas from flowing back to the intake throttle valve 1 side.

On the other hand, the valve portion 6b of the EGR valve 4 is
When the EGR valve 4 that is in contact with the seat portion 3a of the pipe 3 is closed, that is, when the EGR is stopped, the rectifying plate 8 retracts into the EGR pipe 3 and retreats from the intake pipe 2 as shown in FIG. For this reason, it is avoided that the flow of fresh air flowing in the intake pipe 2 is obstructed by the rectifying plate 8. Also,
When the EGR valve 4 is in a closed state, the guide pipe 9 has a so-called tunnel shape.

As described above, according to the present embodiment, the EG
Although it has a simple structure in which the rectifying plate 8 is additionally set to the valve element 6b of the R valve 4, at the time of EGR, the EGR
Gas is prevented from flowing back to the intake throttle valve 1 side, and EGR is prevented.
Since deposits in the gas can be prevented from adhering to the outer peripheral edge of the intake throttle valve 1, the intake throttle valve 1 and the EGR valve 4
Can be placed close to each other, so that E
The miniaturization of the GR device is achieved, which is advantageous for mounting on a vehicle. Further, when the EGR is stopped, the flow of the intake air in the intake pipe 2 is prevented from being obstructed by the rectifying plate 8, so that appropriate intake performance can be maintained.

FIG. 5 shows a second embodiment of the present invention. In this embodiment, the guide tube 9 in the above-described first embodiment is omitted, and the other configuration is the same as that of the first embodiment. Therefore, according to the second embodiment, the EG is smaller than that of the first embodiment.
Even if it is slightly inferior in the effect of preventing the backflow of R gas, it is advantageous in that the number of parts can be reduced and the cost can be reduced by eliminating the guide tube 9, and the obstruction of the intake air flow when the EGR is stopped is further reduced. Becomes

FIG. 6 shows a third embodiment of the present invention. In this embodiment, the inner surface near the connection portion of the current plate 8 with the valve portion 6b is formed as a curved surface 8a, so that the flow direction of the EGR gas flowing from the EGR pipe 3 can be smoothly changed. is there. The other configuration is the same as that of the first embodiment or the second embodiment. Therefore, according to the third embodiment,
By improving the smoothness of the direction change, the flow of the EGR gas is rectified, and the effect of increasing the EGR and preventing the backflow can be further improved.

In the above-described embodiment, the case where the rectifying plate 8 is provided integrally with the valve portion 6b of the EGR valve 4 has been described. However, the rectifying plate 8 is provided in a form independent of the EGR valve 4, and The EGR valve 4 may be configured to project or retract to the intake pipe 2 mechanically or electrically in conjunction with the opening / closing operation of the EGR valve 4. The shape of the current plate 8 is preferably a shape corresponding to the inner surface shape of the EGR pipe 3, but is not necessarily limited to a semi-cylindrical shape.

[0021]

As described in detail above, according to the present invention,
During EGR, exhaust gas can be prevented from flowing back to the intake throttle valve side, and deposits in the EGR gas can be prevented from adhering to the outer peripheral edge of the intake throttle valve 1. Therefore, the intake throttle valve 1, the EGR valve 4, Can be arranged close to each other, and the size of the EGR device can be reduced. Further, when the EGR is stopped, the flow of the intake air in the intake pipe is not obstructed, so that there is no fear of deteriorating the intake characteristics.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an EGR device according to a first embodiment, showing when an EGR valve is opened (at the time of EGR).

FIG. 2 is a cross-sectional view of the EGR device, showing when the EGR valve is closed (when EGR is stopped).

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a perspective view showing a valve portion and a rectifying member of the EGR valve.

FIG. 5 is a sectional view according to a second embodiment.

FIG. 6 is a sectional view according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake throttle valve 2 ... Intake pipe 3 ... EGR pipe 4 ... EGR valve 6 ... Poppet valve 6b ... Valve part 8 ... Rectifier plate 9 ... Guide pipe

Claims (3)

[Claims] 1. An exhaust gas recirculation system comprising: an EGR passage for returning a part of exhaust gas to an intake passage; and an EGR valve for opening and closing the EGR passage. An exhaust gas recirculation device provided with a rectifying member that projects exhaust gas flowing out of the EGR passage toward the downstream side of the intake passage and retracts from the intake passage by closing the EGR valve. 2. The EGR valve according to claim 1, wherein the rectifying member is formed in a valve portion of an EGR valve that opens and closes an outlet of the EGR passage, and enters and exits the outlet of the EGR passage by opening and closing the EGR valve.
A recirculation device as described. 3. The exhaust gas circulation device according to claim 1, wherein a guide member for guiding the EGR gas guided by the rectifying member further downstream is provided in the intake passage.