JPH10122063A - Exhaust gas reflux valve for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce impact noises emitted by the element of an exhaust gas reflux valve with a low-cost means while ensuring its sufficient durability and reliability. SOLUTION: A vacuum actuator 21 is mounted on a valve housing 11 for driving a valve element 18. The vacuum actuator 21 has a rubber diaphragm 24 held between its upper and lower housings 22 and 23 at a crimped part 37. The diaphragm 24 held between two metal plates 27 and 28 receives at its center the upper end of a valve shaft 15 inserted therethrough, which is then crimped and fixed on the diaphragm 24 at the center. The lower metal plate 28 is formed with a plurality of projected lines 31 extended substantially radially for its reinforcement and for establishing its close contact at the outer periphery with the diaphragm 24, by which its vibrations are suppressed at closing the valve and impact noises emitted by the valve element is reduced.

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 valve for an internal combustion engine in which a valve element is driven by a negative pressure actuator.

[0002]

2. Description of the Related Art Conventionally, this type of exhaust gas recirculation valve has been
Japanese Utility Model Laid-Open No. 62-124270, Japanese Utility Model Publication No. 5-2629
As shown in Japanese Patent Application Publication No. 1 (1993), a rubber diaphragm of a negative pressure actuator is sandwiched between two metal plates, and the three members are fixed by caulking through a valve shaft. During the exhaust gas recirculation control, the diaphragm is displaced by the negative pressure of the intake air introduced into the negative pressure actuator, thereby driving the valve element fixed to the valve shaft to control the amount of exhaust gas recirculation. In the driving range where drivability is deteriorated (light load such as idling for gasoline engine and high load such as rapid acceleration for diesel engine), the negative pressure in the negative pressure actuator is released. The valve body is suddenly closed by a spring force to rapidly shut off the recirculation of exhaust gas.

In this exhaust gas recirculation valve, since the fluid to be controlled is a high-temperature and highly corrosive exhaust gas, the valve body and the valve seat are usually formed of stainless steel. For this reason, when the valve element is suddenly closed from the open state, a loud collision sound such as "gacha" is generated by the impact when the valve element collides with the valve seat, and this is heard as unpleasant noise by the driver. There was something.

As a countermeasure against this, Japanese Utility Model Laid-Open No.
In Japanese Patent Publication No. 0, the valve seat is received and supported by a disc spring, and the impact force when the valve body collides with the valve seat is absorbed by the elastic deformation of the disc spring, thereby reducing the valve body collision sound. .

[0005] However, since high-temperature exhaust gas flows in the place where the disc spring is installed, the disc spring is annealed in a short period of time, so that the spring property is reduced and the effect of reducing the valve body collision noise is reduced. There is a disadvantage of doing so. As a countermeasure, it is conceivable to form the disc spring from an expensive material such as heat-resistant ceramic, but even in this case, the valve seat must be slidably mounted in the valve housing, and the engine vibration However, the disadvantage that the valve seat is worn and the sealing performance is apt to deteriorate is not solved.

By the way, the path through which the valve body collision sound leaks out is divided into a sound that leaks out from the valve seat through the valve housing and a sound that leaks out from the metal plate sandwiching the diaphragm through the valve shaft. There is a street. Japanese Utility Model Application Laid-Open No. 62-124270 aims to reduce the impact noise of the valve body at its source. However, since the problems of annealing of the disc spring and wear of the valve seat are newly generated, the valve body is disclosed. As described above, this is not a good solution for reducing the collision sound.

On the other hand, the sound leaking from the metal plate sandwiching the diaphragm to the outside through the valve shaft is a sound leaking from the valve seat through the valve housing because the metal plate vibrates and serves as a speaker cone. The sound is quite loud compared to. Therefore, in order to reduce the valve body collision sound, it is effective to reduce the sound leaking from the metal plate.

From this point of view, Japanese Utility Model Publication No. 5-26291 discloses that a rubber vibration absorbing cylinder is fitted to a connecting portion between a valve shaft and a metal plate to transmit vibration (sound waves) from the valve shaft to the metal plate. The vibration is absorbed by the rubber vibration absorption cylinder to suppress the vibration of the metal plate.

[0009]

However, in the above configuration, since the rubber vibration absorbing cylinder is interposed between the valve shaft and the metal plate, the fixing strength between the valve shaft and the metal plate is weakened. For this reason, the metal plate is tilted due to the unbalanced load of the spring force that urges the diaphragm toward the valve closing side, which further amplifies the unbalanced load and increases the unbalanced load applied to the valve shaft. At times, the valve body is eccentric and collides with the valve seat, and the valve body and the valve seat are unevenly worn, so that the sealing performance is easily deteriorated. In addition, the heat of the high-temperature exhaust gas is transmitted to the rubber vibration absorbing cylinder through the valve shaft, and the rubber vibration absorbing cylinder also has a high temperature. Not only does the sound reduction effect not last for a long time, but it also contributes to the inclination of the valve shaft and "rattle", making the opening and closing operation of the valve body easy to become unstable, ensuring durability and reliability. Have difficulty.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is therefore an object of the present invention to effectively reduce valve body collision noise by inexpensive means while ensuring durability and reliability. And to provide an exhaust gas recirculation valve for an internal combustion engine.

[0011]

According to a first aspect of the present invention, an exhaust gas recirculation valve for an internal combustion engine is provided.
The projection is formed so as to extend at least to the metal plate on the valve housing side of the two metal plates sandwiching the diaphragm of the negative pressure actuator serving as the drive source of the valve shaft. The ridges formed on the metal plate effectively reduce the valve body collision noise by the following actions.

The metal plate is reinforced by ridges to reduce vibration. In order to achieve the same effect, it is conceivable to form the metal plate with a thicker metal plate than before, but if the plate thickness is increased, the weight of the metal plate becomes heavy and inertia increases, and the valve body is correspondingly increased. The impact force colliding with the valve seat increases, the collision noise leaking to the outside through the valve housing from the valve seat increases, and the vibration load acting on the fixed part of the metal plate (portion through the valve shaft) due to engine vibration is increased. The vibration resistance may decrease. In this regard, according to the present invention, by forming the ridge on the metal plate, the metal plate can be effectively reinforced without increasing the weight of the metal plate.

The close contact between the metal plate and the diaphragm is maintained by the reinforcing effect of the ridges. In the exhaust gas recirculation valve of the present invention, the diaphragm is sandwiched between two metal plates, and the three members are fixed by crimping through a valve shaft through a valve shaft. The outer peripheral side is not fixed by crimping. For this reason, as described later, the outer peripheral side of the metal plate is likely to be slightly warped from the diaphragm due to the reaction of the pressing force of the portion of the metal plate that penetrates the valve shaft, and this causes the metal plate to vibrate.
In order to avoid this, in the present invention, the lifting of the outer peripheral portion of the metal plate is prevented by the reinforcing effect of the ridge,
This maintains the close contact between the outer peripheral portion of the metal plate and the diaphragm, and suppresses the vibration of the metal plate with a diaphragm (generally made of rubber).

The vibration of the metal plate at the time of closing the valve can be effectively suppressed by the action of the above-described ridge, and the valve body collision noise can be effectively reduced. Moreover, since it is only necessary to form ridges on the metal plate,
It is not necessary to use a cushioning material such as a spring or rubber as in the known example described above, so that it is possible to satisfy the demand for cost reduction and to reduce durability and reliability by using a cushioning material such as a spring and rubber. Can be avoided, and the durability and reliability required for the exhaust gas recirculation valve can be secured.

In this case, it is preferable that the ridge is constituted by a bead formed on the metal plate. By doing so, the metal plate with the ridges (beads) can be manufactured extremely simply and inexpensively by pressing the metal plate material.

Further, it is preferable that the ridge is formed so as to extend substantially radially. In this manner, the substantially radial strength of the metal plate can be effectively reinforced by the ridges, and the floating of the outer peripheral portion of the metal plate can be more reliably prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
4 through FIG. First, the structure of the exhaust gas recirculation valve will be described with reference to FIG. The valve housing 11 is
An exhaust gas recirculation passage (not shown) for recirculating a part of the exhaust gas of the internal combustion engine (not shown) to the intake system, an inlet 12 of the valve housing 11 is connected to an exhaust pipe side of the internal combustion engine, The outlet 13 is connected to the intake pipe side. An annular valve seat 14 made of, for example, stainless steel is press-fitted and fixed inside the valve housing 11.

In the valve housing 11, a valve seat 14 is provided.
And the valve shaft 15 is arranged on the same coaxial line. The valve shaft 15 is vertically slidably supported by a bearing 17 fixed to the upper end of the valve housing 11 via a bracket 16, and a stainless steel valve element 18 is swaged to the lower end of the valve shaft 15. Fixed. In addition, it surrounds the valve shaft 15 and protects it from heat of exhaust gas.
The two cylindrical bodies 19 and 20 are fixed to the valve body 18 and the bracket 16, and the amount of overlap between the two cylindrical bodies 19 and 20 changes according to the vertical movement of the valve shaft 15.

On the other hand, a negative pressure actuator 21 for driving the valve element 18 is mounted above the valve housing 11. The negative pressure actuator 21 is configured by sandwiching a rubber diaphragm 24 between caulking portions 37 of upper and lower housings 22 and 23, and a lower housing 23.
Are fixed to the upper end of the valve housing 11 by screws 36. Inside the upper housing 22, the diaphragm 2
4 forms a sealed negative pressure introduction chamber 25, and the inside of the lower housing 23 is communicated with the atmosphere through an opening 26 formed in the lower housing 23.

The diaphragm 24 is sandwiched between two metal plates 27 and 28 made of steel plates, penetrates the upper end of the valve shaft 15 through the center of the three members, and the washer 29 is attached to the upper end of the valve shaft 15 from above. The upper end of the valve shaft 15 is fixed to the center of the diaphragm 24 by caulking the upper end of the valve shaft 15 in a state in which is inserted. A spring 30 for urging the diaphragm 24 in the valve closing direction (downward) is housed between the upper metal plate 27 and the upper housing 22.

On the other hand, as shown in FIG. 2, a plurality of linear ridges 31 are formed on the lower metal plate 28 (on the valve housing 11 side) so as to extend radially. In this case, the ridge 31 is formed by a bead which is simultaneously press-formed in the step of press-forming the rib 32 on the outer peripheral portion of the metal plate 28.

As shown in FIG. 1, a pressure control pipe 34 connected to an intake pipe is connected to a connection pipe section 33 provided in the upper housing 22. A pressure regulating valve (not shown) and an electromagnetic valve (not shown) for determining the opening degree of the valve element 18 are provided in the middle of the pressure control pipe 34, and an operating region in which drivability deteriorates due to exhaust gas recirculation. (In the case of light load such as idling in the case of gasoline engine, and in the case of high load such as rapid acceleration in the case of diesel engine)
The solenoid valve is switched to a position where the pressure regulating valve communicates with the atmosphere, introduces atmospheric pressure into the intake negative pressure introduction chamber 25 in the negative pressure actuator 21, and urges the diaphragm 24 downward by the elastic force of the spring 30. And the valve element 18 to the valve seat 14
To shut off the recirculation of exhaust gas. Further, during the exhaust gas recirculation control, the solenoid valve is switched to a position where the intake negative pressure of the intake pipe is introduced into the pressure regulating valve, and the intake negative pressure adjusted by the pressure regulating valve is changed to the intake pressure in the negative pressure actuator 21. The valve 24 is introduced into the negative pressure introducing chamber 25, and the diaphragm 24 is displaced upward in accordance with the negative pressure to adjust the opening degree of the valve element 18 (the amount of exhaust gas recirculated).

Next, when the valve is closed, the valve body 18
Consider the valve body collision sound generated when the valve body 14 collides with the valve seat 14 due to the resilience. First, in the case of the conventional structure shown in FIG.
The reason why the impact sound of the valve body leaking from the outside to the outside becomes large is considered. In the case of the conventional structure, the ridge 31 is not formed on the metal plate 28 (other than that, the structure is the same as the above embodiment). In this structure, the diaphragm 24 is sandwiched between the two metal plates 27 and 28, and the valve shaft 15 is penetrated through the center of the three members and caulked and fixed.
In the metal plate 28, only the central caulking portion (the penetrating portion of the valve shaft 15) is strongly fixed by crimping, and the outer peripheral side is not fixed by crimping. Therefore, since the crimping force acting on the rubber diaphragm 24 acts most strongly on the center caulking portion, the center side of the diaphragm 24 is strongly compressed, the thickness becomes thinner, and the diaphragm 24 becomes closer to the outer peripheral side. The acting crimping force is weakened and the diaphragm 24
Becomes thicker, the outer peripheral side of the metal plate 28 is pushed up by the repulsive force of the rubber of the diaphragm 24 and warps to a state in which it is slightly lifted off the diaphragm 24, and this causes the metal plate 28 to vibrate. Therefore, when the valve is closed, the valve body 18
When the vibration generated by the impact at the time of colliding with the valve seat 14 due to the resilient force of the metal plate 2 is transmitted from the valve body 18 to the valve shaft 15, the vibration
8, the metal plate 28 vibrates and plays a role like a cone of a speaker to generate a loud noise. This loud noise is transmitted to the lower housing 23 through the opening 2 for heat radiation and air communication.
6 is radiated to the outside, and sounds unpleasant to the driver.

On the other hand, in the embodiment shown in FIGS. 1 and 2, by forming the ridge 31 on the metal plate 28,
The following effects can effectively reduce the valve body collision noise.

The metal plate 28 is reinforced by the ridges 31 to increase rigidity. Increasing the rigidity makes the metal plate 28 less likely to vibrate, which is advantageous for lowering noise. Here, as a method of increasing the rigidity of the metal plate 28, it is conceivable to form the metal plate 28 with a thicker metal plate than in the past. However, when the plate thickness is increased, the weight of the metal plate 28 increases and inertia increases. And that much,
The impact force at which the valve element 18 collides with the valve seat 14 increases, and the collision noise leaking to the outside from the valve seat 14 through the valve housing 11 increases. In addition, if the inertia of the metal plate 28 increases, the vibration load acting on the fixed portion of the metal plate 28 (the penetrating portion of the valve shaft 15) due to engine vibration increases, and the vibration resistance and durability may decrease. .

In this regard, in this embodiment, the metal plate 2
By forming the ridge 31 on 8, the metal plate 28 can be effectively reinforced without increasing the weight of the metal plate 28 (decrease in vibration resistance and durability), and the rigidity can be increased. .

The reinforcing effect of the ridges 31 prevents the outer peripheral portion of the metal plate 28 from rising, thereby maintaining the close contact between the outer peripheral portion of the metal plate 28 and the diaphragm 24. That is, as described above, the outer peripheral side of the metal plate 28 tends to be pushed up by the repulsive force of the rubber on the outer peripheral side portion of the diaphragm 24 generated as a reaction to the large caulking force acting on the central portion of the rubber diaphragm 24, Due to the reinforcing effect of the ridges 31, warpage of the outer peripheral portion of the metal plate 28 is suppressed, and the outer peripheral portion of the metal plate 28 and the diaphragm 24
Is maintained in close contact with the substrate. As a result, the diaphragm 24 acts as a buffer for suppressing the vibration of the metal plate 28, and the vibration of the metal plate 28 is suppressed by the diaphragm 24.

The vibration of the metal plate 28 at the time of closing the valve can be effectively suppressed by the action of the ridge 31 described above, and the valve body collision noise can be effectively reduced. By the way, according to the measurement result of the valve body collision sound performed by the inventor, as shown in FIG. 4, the sound pressure waveform of the present embodiment (with the ridge) is smaller than the conventional one (with no ridge), as shown in FIG. The peak value is small, and the sound pressure level is reduced in all frequency bands. As a result, in contrast to the conventional sound pressure of 68.7 dB (OA value), in the present embodiment, 65.4 dB (OA).
Value), and it was confirmed that the valve body collision noise can be reduced by 3.3 dB as compared with the related art.

Further, in the present embodiment, such an excellent effect of reducing the valve body collision sound can be obtained only by forming the protruding ridges 31 on the metal plate 28, so that there is no need to use a cushioning material such as a spring or rubber. The number of parts does not increase, the assemblability can be improved, and the demand for cost reduction can be satisfied. In addition, since there is no need to use a buffer material such as a spring or rubber which causes a decrease in durability and reliability, the durability and reliability required for the exhaust gas recirculation valve can be secured.

Moreover, in the present embodiment, since the ridges 31 are formed so as to extend radially, the strength of the metal plate 28 in the radial direction can be effectively reinforced by the ridges 31 and the outer peripheral portion of the metal plate 28 can be formed. Floating can be prevented more reliably, and the effect of reducing the valve body collision noise can be enhanced.

In the present embodiment, a plurality of linear ridges 31 are formed on the metal plate 28. However, as in the other embodiment shown in FIG. The ridges 35 (beads) of the book may be press-formed almost radially. Even in this case, the radial strength of the metal plate 28 can be effectively reinforced by forming the plurality of ridges 35 substantially radially. Moreover, by curving the ridge 35,
The effect of suppressing the propagation of vibration diffused in the radial direction from the center side to the outer peripheral side of the metal plate 28 can also be expected with the ridge 35, and the vibration suppressing effect is further improved in combination with the reinforcing effect of the ridge 35. Can be done.

In each of the embodiments described above, since the beads are formed by pressing the metal plates 28 as the ridges 31 and 35, the metal plate 28 with the ridges 31 and 35 (beads) can be formed very simply and inexpensively. Can be manufactured and contribute to cost reduction. However, in the present invention, the ridges are not limited to beads, but may be ribs.

In each of the above embodiments, the protruding strips 31 and 35 are formed only on the lower metal plate 28 (side of the valve housing 11) of the two metal plates 27 and 28 sandwiching the diaphragm 24. The upper metal plate 27 may be formed with a ridge so that the upper metal plate 27 is reinforced.

In each of the above embodiments, the ridges 31 and 3 are used.
Although 5 is formed almost only in the radial direction, it may be formed by combining a substantially radially extending ridge with a ridge in the other direction.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an exhaust gas recirculation valve showing an embodiment of the present invention.

FIG. 2A is a plan view of a lower metal plate, and FIG.
FIG. 3A is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a fixed state of a diaphragm and a metal plate in a conventional structure.

FIG. 4 is a diagram showing a measurement result of a valve body collision sound.

FIG. 5 is a plan view of a lower metal plate showing another embodiment of the present invention.

[Explanation of symbols]

11 ... valve housing, 12 ... inlet, 13 ... outlet, 14 ...
Valve seat, 15: Valve shaft, 17: Bearing, 18: Valve body, 2
1: negative pressure actuator, 22, 23: housing, 2
4 ... diaphragm, 25 ... negative pressure introduction chamber, 26 ... opening,
27, 28: metal plate, 30: spring, 31,
35 ... ridge.

Claims (3)

[Claims] 1. A valve housing interposed in an exhaust gas recirculation passage for recirculating exhaust gas from an exhaust system of an internal combustion engine to an intake system, a valve body housed in the valve housing, and a valve shaft supporting the valve body. A negative pressure actuator for driving the valve shaft by a displacement of a diaphragm; an exhaust gas recirculation valve for an internal combustion engine in which the diaphragm is sandwiched between two metal plates and the valve shaft is fixedly inserted through these three members; An exhaust gas recirculation valve for an internal combustion engine, wherein a ridge is formed so as to extend at least on a metal plate on the valve housing side of the metal plates. 2. The exhaust gas recirculation valve for an internal combustion engine according to claim 1, wherein the ridge is constituted by a bead formed on the metal plate. 3. The exhaust gas recirculation valve for an internal combustion engine according to claim 1, wherein the ridge is formed so as to extend substantially radially.