JP2011169213A - Exhaust gas recirculation valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the amount of exhaust gas leakage when foreign matter bites between a valve element and a valve seat and to facilitate detection of the biting of the foreign matter in an exhaust gas recirculation valve. <P>SOLUTION: In this exhaust gas recirculation valve, the valve element 4 includes a conical sealing surface 23 having a diameter that becomes smaller toward one end side in the vertical direction, and on the sealing surface 23, a seal part 24 is formed abutting on the valve seat 11 during seating. An inclination angle θ1 of the sealing surface 23 with respect to the horizontal direction at the seal part 24 is 45-50°, and an inclination angle θ2 further on the inner peripheral side than the seal part 24 is larger than the inclination angle θ1 at the seal part 24. Thereby, even when the valve element 4 is moved to the open side by the biting of the foreign matter, the flow passage area of a valve hole 3 is made small, and the amount of exhaust gas leakage can be reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation valve that is used in an exhaust gas recirculation device for recirculating a part of exhaust gas into an intake pipe and adjusts the flow rate of exhaust gas supplied into the intake pipe.

The exhaust gas recirculation valve is applied to an exhaust gas recirculation device that mixes a part of the exhaust gas discharged from the internal combustion engine into the intake air to the internal combustion engine, and adjusts the flow rate of the exhaust gas mixed into the intake air. It is.
Conventionally, an exhaust gas recirculation valve has a valve hole formed therein, and is capable of reciprocating in a direction perpendicular to the housing having a valve seat formed around the valve hole and the opening surface of the valve hole. Some are provided with a poppet type valve element that opens and closes a valve hole by being attached to and detached from the valve seat.

By the way, since various foreign substances are mixed in the exhaust gas, the exhaust gas recirculation valve may cause a problem of exhaust gas leakage due to the foreign object biting between the valve body and the valve seat when the valve is closed. is there.
Therefore, a technique for detecting foreign object biting and a technique for reducing the exhaust gas leakage by crushing the foreign object bitten are disclosed.

  For example, in Patent Document 1, the motor shaft is driven and the valve body is moved by pushing and moving the valve shaft. From the gap until the motor shaft and the valve shaft come into contact with each other, the gap between the valve body and the valve seat is determined. The foreign object biting is detected.

  However, in the technique of Patent Document 1, since the motor shaft and the valve shaft are also exposed to the exhaust gas, there is a possibility that foreign matter may be caught between the motor shaft and the valve shaft. It is impossible to accurately detect foreign object biting between the valve seat and the valve seat.

  Further, Patent Document 2 discloses a technique for biting or crushing a foreign object that has been caught between a valve body and a valve seat using torque of an actuator that drives the valve body. However, if the foreign matter is hard, it cannot be securely bitten, and exhaust gas leaks due to the biting of the foreign matter.

  There is also a method for detecting the biting of foreign matter by detecting the amount of movement of the valve body to the open side (valve opening amount) by a sensor such as a magnetic sensor. That is, when the sensor detects the valve opening when the valve body must be seated, it is considered that a foreign object is caught.

  However, since the exhaust gas recirculation valve is a component made up of multiple parts, the valve opening cannot be detected in a region where the valve opening amount is very small due to the accumulation of dimensional tolerances of parts and the effect of gaps between parts. It becomes an insensitive area. For this reason, it is possible to detect the biting of the foreign matter only with the valve opening amount exceeding the insensitive area. Further, there is a problem that the flow area of the valve hole when the valve opening amount exceeds the insensitive region is large, and the foreign matter can be detected only after the leakage amount of the exhaust gas becomes large.

JP 2005-299514 A JP 2007-309115 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to leak exhaust gas when a foreign object is caught between a valve body and a valve seat in an exhaust gas recirculation valve. It is to reduce the amount and make it easy to detect biting of foreign matter.

[Means of Claim 1]
The exhaust gas recirculation valve according to claim 1 has a valve hole formed therein, a housing having a valve seat formed around the valve hole, and a reciprocation in a direction perpendicular to the opening surface of the valve hole. A poppet-type valve body that is provided so as to be movable and opens and closes a valve hole by being attached to and detached from one end of the valve seat in the vertical direction.

Further, the valve body has a conical sealing surface having a diameter that decreases toward the other end in the vertical direction, and a seal portion that contacts the valve seat when seated is formed on the sealing surface.
And the inclination | tilt angle (theta) 1 of the sealing surface with respect to the horizontal direction in a seal part is 45-50 degrees, and the inclination | tilt angle of the inner peripheral side is larger than inclination | tilt angle (theta) 1 from a seal part.

When the valve body is formed in a conical shape so that its diameter decreases toward the other end in the vertical direction (closed side), the valve is opened by the valve body when the valve body is moved away from the seat and moved to the open side. The flow area of the holes gradually increases and the flow rate increases. The expansion gradient (flow rate increase gradient) of the flow path area depends on the shape of the portion closing the valve hole on the inner peripheral side with respect to the seal portion.
Therefore, by increasing the inclination angle θ1 of the sealing surface with respect to the horizontal direction on the inner peripheral side of the seal portion, the amount of movement (opening) of the valve body in the small valve opening amount region to the one end side (opening side) in the vertical direction is increased. The expansion gradient of the channel area with respect to the valve amount) can be reduced.

  According to this, when the valve body is moved to the closed side, the foreign body bites into the inner peripheral side (part where the foreign body is generally easy to bite) than the seal portion. Even when the valve has moved to the open side, the flow area of the valve hole can be small, so that the amount of exhaust gas leakage can be reduced.

Moreover, the fact that the expansion gradient of the channel area with respect to the valve opening amount can be reduced means that the valve opening amount greatly changes even when the channel area is slightly increased.
For this reason, even when the flow path is slightly expanded due to the biting of foreign matter, the valve opening amount becomes large, and it becomes possible to detect the biting of foreign matter beyond the dead area. That is, the flow passage area of the valve hole in the valve opening amount exceeding the dead area is small, and it is possible to detect the entry of foreign matter while the exhaust gas leakage amount is small.

Further, the inclination angle θ1 of the seal surface with respect to the horizontal direction in the seal portion is set to 45 to 50 °. When the inclination angle θ1 at the seal portion is large, the valve body may be fitted into the valve seat and fixed at the time of seating. When the inclination angle θ1 at the seal portion is small, the valve body and the valve seat at the time of seating may be present. There is a risk that the roughness of the seal surface will increase due to the collision with the.
Therefore, by setting the inclination angle θ1 at the seal portion to 45 to 50 °, sticking of the valve body to the valve seat during seating and roughening of the seal surface can be suppressed.

[Means of claim 2]
According to the exhaust gas recirculation valve of the second aspect, the seal surface is formed in a concave shape.
According to this, in addition to the effect similar to that of the first aspect, by making the seal surface concave, the expansion gradient of the flow path area with respect to the valve opening amount can be smoothed, and control becomes easy.

(Example 1) which is sectional drawing of an exhaust-gas recirculation valve | bulb. (A) is a principal part enlarged view of FIG. 1, (b) is explanatory drawing regarding the movement of a valve body (Example 1). (Example 1) regarding the movement of the valve body at the time of foreign object biting. (A) is a figure which shows the correlation of valve opening amount and flow volume, (b) is the correlation diagram which expanded the area | region where the valve opening amount of (a) is small (Example 1). (Example 2) which is a principal part expanded sectional view of an exhaust-gas recirculation valve | bulb.

  An exhaust gas recirculation valve according to an embodiment of the present invention is applied to an exhaust gas recirculation device that mixes a part of exhaust gas discharged from an internal combustion engine into intake air into the internal combustion engine, and is mixed into intake air. Adjust the flow rate of exhaust gas.

  The exhaust gas recirculation valve is provided with a valve hole formed therein, a housing having a valve seat formed around the valve hole, and a reciprocating movement in a direction perpendicular to the opening surface of the valve hole. And a poppet-type valve body that opens and closes the valve hole by being attached to and detached from one end of the valve seat in the vertical direction.

Further, the valve body has a conical sealing surface having a diameter that decreases toward the other end in the vertical direction, and a seal portion that contacts the valve seat when seated is formed on the sealing surface.
And the inclination | tilt angle (theta) 1 of the sealing surface with respect to the horizontal direction in a seal part is 45-50 degrees, and the inclination | tilt angle of the inner peripheral side is larger than inclination | tilt angle (theta) 1 from a seal part.

[Configuration of Example 1]
The configuration of the exhaust gas recirculation valve 1 according to the first embodiment will be described with reference to FIGS.
The exhaust gas recirculation valve 1 is applied to an exhaust gas recirculation device that mixes a part of the exhaust gas discharged from the internal combustion engine into the intake air to the internal combustion engine, and adjusts the flow rate of the exhaust gas mixed into the intake air. Is.
The exhaust gas recirculation device has a reflux pipe that connects an exhaust pipe for exhausting exhaust gas from the internal combustion engine and an intake pipe for supplying intake air to the internal combustion engine, and the exhaust gas recirculation valve 1 Is disposed in the middle of the reflux pipe.

  The exhaust gas recirculation valve 1 generates a housing 2 connected in the middle of the reflux pipe, a valve body 4 that opens and closes a valve hole 3 formed in the housing 2, and a driving force for moving the valve body 4. And an actuator 5 for the purpose.

  The housing 2 has a reflux path 8 formed therein, and between the exhaust pipe side of the reflux path 8 (hereinafter referred to as the reflux path upstream 9) and the intake pipe side of the reflux path 8 (hereinafter referred to as the reflux path downstream 10). A substantially circular valve hole 3 is formed. A valve seat 11 is provided around the valve hole 3.

The valve body 4 is a poppet type, is provided so as to be reciprocally movable in the direction perpendicular to the opening surface of the valve hole 3, and opens and closes the valve hole 3 by being attached to and detached from the valve seat 11.
The valve body 4 is provided at one end of the valve shaft 13, the driving force of the actuator 5 is transmitted to the valve shaft 13, and the valve body 4 reciprocates in the vertical direction integrally with the valve shaft 13.

In this embodiment, when the valve body 4 moves to one end in the vertical direction, the valve body 4 opens from the one end face in the vertical direction of the valve seat 11 and opens when the valve body 4 moves to the other end in the vertical direction. It sits on one end face in the vertical direction of the seat 11 and closes the valve.
When the valve hole 3 is opened, the exhaust gas flows from the reflux path upstream 9 to the valve hole 3 → the reflux path downstream 10 and is supplied to the intake pipe.

  The actuator 5 includes a motor 15 that generates a rotational driving force, and a drive conversion unit 16 that converts the rotational driving force by the motor 15 into a driving force in the vertical direction. The drive conversion unit 16 has a shaft 17 provided on the other end side of the valve shaft 13. Then, the rotational driving force by the motor 15 is transmitted to the shaft 17 through the gear portion, and the rotation of the shaft 17 is converted into the movement in the vertical direction by the lead screw formed on the shaft 17, whereby the valve shaft 13. Move vertically.

  Further, the exhaust gas recirculation valve 1 includes a rotational position detection device 20 that detects a movement amount (valve opening amount) of the valve element 4 toward one end side (open side) in the vertical direction based on the rotational position. The rotational position detection device 20 is a well-known device using a magnetic sensor 21.

[Features of Example 1]
According to the exhaust gas recirculation valve 1 of the first embodiment, the valve body 4 has a conical seal surface 23 that decreases in diameter toward the other end in the vertical direction. A seal portion 24 that contacts the valve seat 11 is formed (see FIG. 1).

  The seal surface 23 is formed as a series of concave surfaces such that the inclination angle θ1 with respect to the horizontal direction of the tangent line at the seal portion 24 is 45 to 50 °. For this reason, the inclination angle θ2 on the inner peripheral side with respect to the seal portion 24 is larger than the inclination angle θ1 at the seal portion 24 (see FIG. 2A).

[Effects of Example 1]
The effect of Example 1 is demonstrated comparing with the comparative example demonstrated below.
In the valve body 4 of the comparative example, the seal surfaces 23 all have the same inclination angle θ1, and the outer periphery of the valve body 4 is formed in a linear inclination in the cross-sectional shape of the valve body 4 (FIG. 2 ( b)).
On the other hand, in the valve body 4 of the first embodiment, the seal surface 23 is formed in a concave shape in the cross-sectional shape of the valve body 4.

  As shown in FIG. 2B, when the minimum flow area of the valve hole 3 with the same valve opening amount in the small valve opening amount region is compared between the first embodiment and the comparative example, the seal portion in the first embodiment is compared. Since the inclination angle θ2 of the seal surface 23 on the inner periphery is larger than 24, the minimum flow path area is smaller than in the comparative example.

  For this reason, in Example 1, the increase amount of the flow rate (depending on the flow path area) with respect to the valve opening amount in the small valve opening amount region is smaller than in the comparative example (see FIG. 4). That is, in the valve body shape of the first embodiment, the expansion gradient of the flow path area with respect to the valve opening amount of the valve body 4 in the small valve opening amount region can be reduced.

  According to this, in the first embodiment, when the valve is closed, the foreign body bites into the inner peripheral side (a part where the foreign substance is particularly easy to bite) more than the seal portion 24, and the valve body 4 is opened. Even if it has moved to the side, the flow passage area of the valve hole 3 may be smaller than in the comparative example, and the amount of exhaust gas leakage can be reduced.

  Further, the opening amount when foreign matter is caught between the seal surface 23 on the inner peripheral side of the seal portion 24 and the valve seat 11 is compared between the first embodiment and the comparative example. As an example, comparison is made with a model in which spherical foreign substances having the same diameter are inserted (see FIG. 3).

  The amount of valve opening in a state where the amount of leakage becomes maximum when this foreign matter is bitten (the shortest distance between the valve body 4 and the valve seat 11 matches the diameter of the foreign matter) is compared in the first embodiment. Bigger than the example. This is also apparent from the correlation between the valve opening amount and the flow rate shown in FIGS. 4 (a) and 4 (b).

As shown in FIGS. 4A and 4B, in Example 1, the expansion gradient of the flow path area with respect to the valve opening amount in the small valve opening amount region can be made smaller than in the comparative example. That is, in the small valve opening amount region, the valve opening amount greatly changes even when the flow path area is slightly increased.
For this reason, in the small valve opening amount region, when compared at the same flow rate (leakage amount), the valve opening amount in Example 1 is larger than that in the comparative example (see FIG. 4B).

The detection of biting of foreign matter in the exhaust gas recirculation valve 1 is performed by detecting the valve opening amount of the valve body 4 by the rotational position detection device 20. That is, when the rotational position detection device 20 detects the valve opening when the valve body 4 must be seated, it is considered that a foreign object is caught.
However, since the exhaust gas recirculation valve 1 is a component made up of multiple parts, the valve opening is detected in a region where the valve opening amount is very small due to the increase in the dimensional tolerances of parts and the effect of gaps between parts. It becomes an insensitive area that cannot be performed (see FIG. 4B).

Here, since the valve opening amount at the same flow rate in Example 1 is larger than that in the comparative example, when the foreign matter of the same size is caught, the valve opening amount is in the insensitive region in the comparative example. In contrast to the fact that the valve cannot be detected and biting of the foreign matter cannot be detected, in Example 1, the amount of valve opening exceeds the insensitive region, so that biting of the foreign matter can be detected.
In other words, in Example 1, the flow rate of the valve opening amount exceeding the dead zone is smaller than that of the comparative example, and it is possible to detect the biting of foreign matter while the exhaust gas leakage amount is small.

  As described above, the first embodiment can reduce the amount of exhaust gas leakage when foreign matter is caught between the valve body 4 and the valve seat 11 as compared with the comparative example. Easy to detect.

Moreover, in Example 1, the inclination | tilt angle (theta) 1 of the seal surface 23 with respect to the horizontal direction in the seal part 24 is 45-50 degrees. When the inclination angle θ1 at the seal portion 24 is large, the valve body 4 may be fitted and fixed to the valve seat 11 when seated. When the inclination angle θ1 at the seal portion 24 is small, the valve body 4 may be fixed when seated. There is a possibility that the roughness of the seal surface 23 increases due to the collision between the body 4 and the valve seat 11.
Therefore, by setting the inclination angle θ1 at the seal portion 24 to 45 to 50 °, it is possible to suppress the sticking of the valve body 4 to the valve seat 11 and the roughening of the seal surface 23 at the time of seating.

[Configuration of Example 2]
The configuration of the exhaust gas recirculation valve 1 according to the second embodiment will be described with reference to FIG. 5 with a focus on differences from the first embodiment.
In the exhaust gas recirculation valve 1 according to the second embodiment, the seal surface 23 is formed by two stages of tapered surfaces 26 and 27.

  The taper surface 26 on one end side in the vertical direction including the seal portion 24 has an inclination angle θ1 set to 45 to 50 °. Further, the taper surface 27 on the inner peripheral side of the seal portion 24 is set to an inclination angle θ2 larger than the inclination angle θ1.

  Thereby, Example 2 can also have the same effect as Example 1. The valve body shape (concave surface) of the first embodiment is more preferable than the valve body shape (second-stage taper) of the second embodiment from the viewpoint of smoothing and controlling the flow rate change accompanying the increase in the valve opening amount. preferable.

DESCRIPTION OF SYMBOLS 1 Exhaust gas recirculation valve 2 Housing 3 Valve hole 4 Valve body 11 Valve seat 23 Seal surface 24 Seal part

Claims (2)

This is an exhaust gas recirculation valve that is applied to an exhaust gas recirculation device that mixes a part of exhaust gas discharged from an internal combustion engine into the intake air to the internal combustion engine and adjusts the flow rate of the exhaust gas mixed into the intake air. And
A housing having a valve hole formed therein and a valve seat formed around the valve hole;
A poppet-type valve body that is provided so as to be reciprocally movable in the vertical direction with respect to the opening surface of the valve hole, and opens and closes the valve hole by detaching and seating on one end side in the vertical direction of the valve seat;
The valve body has a conical sealing surface whose diameter becomes smaller toward the other end in the vertical direction,
On the seal surface, a seal portion that contacts the valve seat when seated is formed,
An inclination angle θ1 of the seal surface with respect to the horizontal direction in the seal portion is 45 to 50 °,
An exhaust gas recirculation valve, wherein an inclination angle on an inner peripheral side of the seal portion is larger than the inclination angle θ1. The exhaust gas recirculation valve according to claim 1,
The exhaust gas recirculation valve, wherein the seal surface is formed in a concave shape.

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