JP3539076B2 - On-off valve structure for exhaust gas recirculation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle engine,
Particularly, the present invention relates to an on-off valve structure for an exhaust gas recirculation device, which is suitable for use in a diesel engine.

[0002]

2. Description of the Related Art Conventionally, in order to reduce NOx (nitrogen oxide) contained in exhaust gas of an internal combustion engine (engine),
2. Description of the Related Art An exhaust gas recirculation device (hereinafter, referred to as an EGR device) that recirculates a part of exhaust gas of an engine to an intake system according to an operation state of the engine has been developed and put into practical use.

In such an EGR device, an exhaust system (mainly, an exhaust passage) and an intake system (mainly, an intake passage) of an engine are controlled by an E.
An on-off valve (EGR valve) for an exhaust gas recirculation device, which is connected via a GR passage and controls an exhaust gas recirculation ratio, is provided in the EGR passage. The opening degree of the EGR valve is controlled by, for example, a negative pressure in an intake pipe or an exhaust pressure in an exhaust pipe, whereby an amount of recirculated exhaust gas is adjusted.

The EGR system mixes exhaust gas (EGR gas) taken in from the exhaust system into intake air to slow down the combustion temperature in the combustion chamber and suppress the generation of NOx. It is.
Among such EGR devices, Japanese Utility Model Laid-Open Publication No. 3-65850 discloses an EGR valve 103 as shown in FIG. Here, a connection passage 102A having a required pipe length L extends from the EGR valve 103 to the exhaust passage 101.
Connected by Note that the connection passage 102A is
This is a passage that forms a part of the GR passage 102. And
One end of the EGR passage 102 is connected to an intake passage (not shown).

When the EGR valve 103 is opened, a part of the exhaust gas flowing through the exhaust passage 101 becomes E
The exhaust gas is taken into the GR passage 102 and recirculated into the intake passage. Here, the detailed structure of the EGR valve is omitted. By the way, in general,
When the EGR valve 103 is opened, the pressure difference between the EGR passage 102 and the exhaust passage 101 and the EGR valve 103
Exhaust gas flows into the EGR passage 102 from the exhaust passage 101 according to the effective opening area of the EGR.

[0006] Of these, the effective opening area is proportional to the valve lift amount.
The amount of R gas can be increased.

[0007]

SUMMARY OF THE INVENTION However, EGR
As described above, the gas recirculation amount is affected not only by the valve lift (effective opening area) but also by the pipe pressure difference (the pressure difference between the EGR passage 102 and the exhaust passage 101). In the case of the structure, there is a problem that a necessary EGR gas flow rate may not be obtained in a light load region or a low speed region where the pressure difference is small.

That is, in the above case, the inside of the connection passage connecting the exhaust gas to the EGR valve is in a static state in which the exhaust gas does not normally flow.
On the other hand, fluid moves from high pressure to low pressure as a basic static property. Therefore, the inside of the connection passage and the EGR
If the pressure difference from the inside of the passage is small, there may be a case where a desired amount of EGR gas flow rate cannot be obtained even if the flow velocity of the exhaust gas flowing through the exhaust passage is large.

Therefore, it is conceivable that the EGR valve is configured to directly protrude into the exhaust passage when the EGR valve is opened so that the kinetic energy of the exhaust gas is actively used to take in the exhaust gas. However, even with such a configuration, there is a problem that a sufficient EGR gas flow rate cannot be obtained. The present invention has been made in view of such a problem, and is intended for an exhaust gas recirculation device that can take in sufficient recirculated exhaust gas even when the pressure difference between the exhaust pipe side and the intake pipe side is small. An object of the present invention is to provide an on-off valve structure.

[0010]

According to the first aspect of the present invention, there is provided an on-off valve structure for an exhaust gas recirculation apparatus according to the present invention, wherein an exhaust gas recirculation system is provided between an exhaust passage and an intake passage of an engine. In an exhaust gas recirculation device including a passage and an on-off valve for adjusting an amount of exhaust gas flowing into the exhaust gas recirculation passage, the on-off valve is a poppet valve including a shaft portion and an umbrella portion. And a head portion of the on-off valve protrudes into the exhaust passage when the on-off valve is lifted, and a guide portion for introducing the exhaust gas into the exhaust gas recirculation passage is provided in the head portion. The guide portion is provided as a wall portion standing upright on the umbrella portion and having an opening on the upstream side of the exhaust passage , and the guide portion is provided on the exhaust passage.
A wall having an opening on the upstream side, and a wall provided inside the wall.
From the opening side toward the downstream side of the exhaust gas.
A raised ridge is provided .

[0011] The exhaust gas recirculation device for opening and closing valve structure of the present invention according to claim 2, the intake passage and exhaust passage of the engine
An exhaust gas recirculation passage interposed between the exhaust gas
For adjusting the amount of gas flowing into the exhaust gas recirculation passage.
In an exhaust gas recirculation system having a valve closing,
The valve is configured as a poppet valve consisting of a shaft and an umbrella.
When the on-off valve is lifted, the head of the on-off valve is connected to the exhaust passage.
And the drainage
A guide section for introducing gas gas into the exhaust gas recirculation passage is provided.
The guide portion is erected on the umbrella portion and
Constructed as a wall with an opening upstream of the exhaust passage
In addition, the opening width of the opening depends on the lift amount of the shaft.
It is characterized by being gradually widened.

[0012]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, a description will be given of an on-off valve structure for an exhaust gas recirculation apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an exhaust passage, and 2 denotes an exhaust gas recirculation passage. is there. The exhaust passage 1 is a passage for guiding exhaust gas discharged from an engine (not shown) to a muffler, a catalyst, and the like (both not shown), and an upstream side (left side in the figure) is connected to the engine, and a downstream side. The side is connected to a muffler, a catalyst and the like.

An exhaust gas recirculation passage (hereinafter, EGR)
2) is interposed between the exhaust passage 1 and an intake passage (not shown). Reference numeral 3 denotes an on-off valve for an exhaust gas recirculation device (hereinafter, referred to as an EGR valve).
It is provided at a connection between the R passage 2 and the exhaust passage 1. The EGR passage 2 and the EGR valve 3
Exhaust gas recirculation system (hereinafter referred to as EGR system)
And a part of the exhaust gas is recirculated from the EGR passage 2 to the intake passage in accordance with the operation state of the engine.

Further, the opening degree of the EGR valve 3 is controlled by a controller (not shown) according to the negative pressure in the intake passage and the exhaust pressure in the exhaust passage 1. Gas recirculation (or reflux ratio)
Is to be adjusted. And such E
Exhaust gas (EG
By mixing (R gas) into the intake air, the combustion in the combustion chamber is slowed down, the combustion temperature is lowered, and the generation of NOx is suppressed.

Here, the main part of the present invention will be described. As shown in FIG.
Is configured as a so-called poppet valve having a shaft portion (or a valve stem) 5 and an umbrella portion 6, and the valve body 4 is configured to be able to reciprocate in the axial direction of the valve stem 5. When the valve body 4 is lifted, the umbrella portion 6 of the valve body 4 is configured to protrude into the exhaust passage 1.

The umbrella section 6 is provided with a guide section 7 as shown in FIGS. This guide part 7
Is provided for efficiently guiding the exhaust gas into the EGR passage 2 using the kinetic energy of the exhaust gas in the exhaust passage 1. The guide portion 7 will be described below. As shown in FIGS. 2A and 2C, the guide portion 7 has a wall portion 9 and a raised portion 10. this house,
The wall portion 9 is erected on the umbrella portion 6 along the axial direction of the valve stem 5 and, as shown in the front view of FIG. An opening 8 is formed at the opposing portion. The width of the opening 8 is
The valve stem 5 is formed so as to be substantially constant along the axial direction.

On the other hand, the raised portion 10 is formed inside the wall portion 9 and has a cross-sectional shape such that it gradually rises toward the downstream side of the exhaust passage 1 as shown in FIG. are doing. Although not shown in detail, a key is formed on the valve stem 5 along the axial direction of the valve stem 5, while a key on which the key of the valve stem 5 can slidably contact the valve stem guide 11. A groove is formed. Thus, rotation of the valve body 4 around the valve stem 5 is prevented.

In FIG. 1, reference numeral 12 denotes a valve seat that comes into contact with the valve body 4 when the valve is closed. Since the on-off valve structure for an exhaust gas recirculation device as one embodiment of the present invention is configured as described above, when the valve body 4 is lifted, a part of the exhaust gas flowing in the exhaust passage 1 It is taken in from the opening 8 of the guide portion 7 and is smoothly guided into the EGR passage 2 along the raised portion 10.

Then, even if the difference between the pressure in the EGR passage 2 and the pressure in the exhaust passage 1 is small, opening the EGR valve 3 ensures that the EGR passage 2 is opened.
Exhaust gas can be introduced into the For example, there is a demand to recirculate more EGR gas when the engine is under a low load, at a low speed, and the like.
Since the pressures in the R passage 2 and the exhaust passage 1 are both low and the pressure difference is relatively small, the flow rate of the exhaust gas introduced into the EGR passage 2 could not be expected so far.

On the other hand, when the EGR valve 3 is opened by providing the guide portion 7 in the EGR valve 3 and positively utilizing the kinetic energy (dynamic pressure) due to the flow of the exhaust gas as in this structure. Even if the difference between the internal pressure of the EGR passage 2 and the internal pressure of the exhaust passage 1 is small, sufficient exhaust gas can be recirculated. Here, the flow rate characteristics of the EGR gas when this structure is applied will be described with reference to FIG. 3. The line in FIG. 3 shows the flow rate characteristics of the EGR valve 3 provided with such a guide portion 7. The line shows the flow characteristics when the guide 7 is not provided. Thus, according to the on-off valve structure for an exhaust gas recirculation device of the present invention, a sufficient amount of EGR gas can be taken in even with a small valve lift.

Further, according to the present structure, there is an advantage that the cost and the weight hardly increase due to such a simple configuration. Next, a description will be given of a modified example of the present invention. In this modified example, the guide portion 7 is configured substantially in the same manner as in the above-described embodiment, and an opening formed in the wall portion 9 is different from the above-described embodiment. Only the shape of the portion 8 is different.

That is, as shown in FIG. 4, in this modification, the opening width of the opening 8 is gradually increased upward along the axial direction of the shaft 5. When the opening 8 is configured in this manner, it is possible to obtain the flow characteristics of the EGR gas as shown by the line in FIG. That is, according to such a shape of the opening 8, when the valve lift amount is small, the area of the opening 8 is small, so that the EGR
The flow rate of EGR gas taken into the EGR passage 2 via the valve 3 can also be suppressed.

Therefore, when the EGR gas is not required much (ie, when the valve lift is not so large), the sensitivity to the change in the valve lift can be relatively reduced, and the inflow of the EGR gas can be reduced. There is an advantage that adjustment is easy. Conversely, E
When a large amount of the GR gas is required (that is, when the valve lift amount is large), the area of the opening 8 changes relatively largely with the change in the valve lift, so that a large amount of the EGR gas can be taken in. .

As described above, in the on-off valve structure for an exhaust gas recirculation device according to the present invention, the required flow characteristics can be obtained only by a relatively simple operation of changing the shape of the guide portion 7. It also has the advantage that it can be done. Note that the shape of the opening 8 and the shape of the raised portion 9 in the guide portion 7 are not limited to those in the above-described embodiment, and may be changed according to the required flow characteristics of the exhaust gas. .

[0026]

As described above in detail, according to the first aspect of the present invention, the exhaust gas interposed between the exhaust passage and the intake passage of the engine is provided. In an exhaust gas recirculation device including a recirculation passage and an on-off valve for adjusting an amount of exhaust gas flowing into the exhaust gas recirculation passage, the on-off valve includes a shaft portion and an umbrella portion. A guide configured to protrude into the exhaust passage when the on-off valve is lifted, and to guide the exhaust gas to the exhaust gas recirculation passage through the umbrella; A guide portion, the guide portion is formed upright on the umbrella portion and is configured as a wall portion having an opening upstream of the exhaust passage , and the guide portion is provided on the exhaust passage.
A wall having an opening on the flow side; and a wall provided inside the wall.
Gradually rising from the opening side toward the exhaust gas downstream side
Is provided, even when the difference between the pressure in the exhaust gas recirculation passage and the pressure in the exhaust passage is small when the on-off valve for the exhaust gas recirculation device is opened, There is an advantage that a sufficient amount of exhaust gas can be reliably recirculated by positively utilizing the kinetic energy of the exhaust gas.

Further, there is an advantage that can be realized relatively easily the structure without incurring little costs increase and weight increase.

Further, when opening the opening closed, a portion of the exhaust gas flowing through the exhaust passage is taken from the opening of the guide portion, smoothly guided to the exhaust gas recirculation passage along the ridge Is done. Therefore, there is also an advantage that the kinetic energy due to the flow of the exhaust gas can be positively used, and a sufficient amount of the exhaust gas can be reliably recirculated.

According to a second aspect of the present invention, there is provided an on- off valve structure for an exhaust gas recirculation device.
When the on-off valve is opened, the pressure in the exhaust gas recirculation
Even if the difference with the pressure in the exhaust passage is small, the exhaust
Active use of the kinetic energy of the gas flow
It is said that a sufficient amount of exhaust gas can be reliably recirculated
In addition to the effect, the opening width of the opening, the configuration that is gradually wider in accordance with the lift amount of the shaft portion, when not require much recirculated exhaust gas, the lift-height change of the on-off valve Sensitivity can be relatively low,
There is an advantage that it is easy to finely adjust the inflow amount of exhaust gas. In addition, when a large amount of recirculated exhaust gas is required, the area of the opening changes relatively greatly with a change in the lift amount of the on-off valve, so that there is an advantage that a large amount of exhaust gas can be taken in. Another advantage is that the required flow characteristics can be changed only by a relatively simple operation of changing the shape of the guide portion.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing the overall configuration of an on-off valve structure for an exhaust gas recirculation device as one embodiment of the present invention.

FIG. 2 is a schematic view showing a main part of an on-off valve structure for an exhaust gas recirculation device as one embodiment of the present invention,
(A) is a top view thereof, (b) is a front view thereof, and (c) is a sectional view taken along the line AA in (b).

FIG. 3 is a diagram showing flow characteristics of recirculated exhaust gas in an on-off valve structure for an exhaust gas recirculation device as one embodiment of the present invention.

FIG. 4 is a schematic view showing a modification of the on-off valve structure for an exhaust gas recirculation device as one embodiment of the present invention.
It is a figure corresponding to (b).

FIG. 5 is a diagram showing a configuration of a general on-off valve for an exhaust gas recirculation device.

[Explanation of symbols]

1 Exhaust passage 2 Exhaust gas recirculation passage (EGR passage) 3 On-off valve for exhaust gas recirculation device (EGR valve) 4 Valve body 5 Shaft (or valve stem) 6 umbrella club 7 Guide part 8 opening 9 Wall 10 ridge 11 Valve stem guide 12 Valve seat 101 Exhaust passage 102 Exhaust gas recirculation passage (EGR passage) 102A passage 103 On-off valve for exhaust gas recirculation device (EGR valve)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01L 3/06 F02M 25/07 580

Claims (2)

(57) [Claims] An exhaust gas recirculation passage interposed between an exhaust passage and an intake passage of an engine, and an on-off valve for adjusting an amount of exhaust gas flowing into the exhaust gas recirculation passage. In the exhaust gas recirculation device, the on-off valve is configured as a poppet valve including a shaft portion and an umbrella portion, and the umbrella portion of the on-off valve projects into the exhaust passage when the on-off valve is lifted. And a guide portion for introducing the exhaust gas into the exhaust gas recirculation passage is provided in the umbrella portion, and the guide portion is erected on the umbrella portion and has an opening upstream of the exhaust passage. is configured as a wall portion and having a, the guide portion, the wall having an opening on the upstream side of the exhaust passage
Part, and the exhaust gas provided from the side of the opening provided inside the wall part.
A ridge that gradually rises toward the downstream side
Characterized that, the exhaust gas recirculation device for closing valve structure that are. 2. Between an exhaust passage and an intake passage of an engine.
An interposed exhaust gas recirculation passage, and the exhaust gas
And an on-off valve for adjusting the amount of inflow to the recirculation passage.
In the exhaust gas recirculation system, the on- off valve is configured as a poppet valve including a shaft portion and an umbrella portion.
When the on-off valve is lifted, the umbrella of the on-off valve
It is configured to protrude into the passage and
A guide section for introducing the exhaust gas into the exhaust gas recirculation passage
The guide portion is provided upright on the umbrella portion and the exhaust passage is provided.
And the opening width of the opening is gradually increased according to the lift amount of the shaft.
Exhaust gas recirculation characterized by widespread formation
On-off valve structure for equipment.