JP2011122659A - Butterfly valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability EGR valve capable of suppressing increase of contact pressure associated with aperture increase to suppress occurrence of local wear even when used over a long term. <P>SOLUTION: This EGR valve includes a ball valve element 4 rotatably driven in an EGR passage, and a sheet member 5 energized toward the ball valve element 4, wherein "a spherical surface of a ball surface 4a" formed at an outer peripheral edge of the ball valve element 4 and "a spherical surface of a sheet surface 5a" formed at an edge of the sheet member 5 are formed so that curvature factors thereof coincide with each other. Projecting parts 9 fit in a projection area of a shaft 8 are formed protrusively in an inner diameter direction on the upper and lower sides of the sheet member 5, and the sheet surface 5a is locally expanded by the projecting parts 9 to suppress increase of contact pressure associated with aperture increase. Thereby, local wear can be prevented by preventing increase of physical constitution, and leakage of an EGR gas can be prevented over a long term. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a butterfly valve that opens and closes a fluid passage or changes the passage area of a fluid passage by rotation of a ball valve body. For example, exhaust gas discharged from an engine (an internal combustion engine that generates power by burning fuel) The present invention relates to a technique suitable for use in an EGR valve or the like for returning a part of the valve to an intake passage.

As a component of the butterfly valve, at least
(I) a ball valve body (valve body) having a ball surface (seat surface on the rotating side) constituted by a part of a spherical surface;
(Ii) a seat member (valve seat member) having an annular seat surface (non-rotating side seat surface) whose curvature substantially matches the ball surface;
(Iii) using a surface pressure generating means that urges the seat member toward the ball valve body and enhances the sealing performance when the valve is closed;
A so-called “ball valve type” butterfly valve that achieves “ensurement of sealing performance when the valve is closed” and “improvement of slidability when the ball valve body rotates” is known (for example, see Patent Document 1). ).

In this “ball valve type” butterfly valve, when the ball valve body rotates, the ball valve body rotates with respect to the seat member in a state where the curvature of the ball surface and the curvature of the seat surface substantially coincide with each other. Therefore, the ball valve body can be smoothly rotated with respect to the seat member.
However, as the valve is opened from the closed state, the contact area between the ball surface of the ball valve body and the seat surface of the seat member decreases. As a result, as the valve is opened, as shown by the solid line B in FIG.
As a result, local wear may occur at the contact portion between the ball valve body and the seat member due to long-term use, and fluid may leak from the worn portion when fully closed.

JP 2005-344803 A

  The present invention has been made in view of the above problems, and its purpose is to suppress an increase in surface pressure accompanying an increase in opening, and to suppress the occurrence of local wear even when used for a long time. It is to provide a butterfly valve that can ensure reliability.

[Means of Claim 1]
The sheet member of the means according to claim 1 includes, in a part of the sheet member, a convex portion that locally protrudes to at least one of the “inner diameter direction” or “the direction of approaching the shaft when the sheet member is viewed from the side surface”. .
The convex portion is provided so as to locally widen the width of the seat surface in “a portion that is in sliding contact with the ball surface as the degree of opening of the ball valve body increases (a portion where the surface pressure increases in the prior art)”. ing.
As a result, even if the ball valve body rotates and the opening degree increases, a large contact area between the ball surface of the ball valve body and the seat surface of the seat member can be secured, and the surface pressure of the contact portion is reduced. It can be kept low.
For this reason, in addition to the effects of the “ball valve type” (that is, “ensurement of sealing performance when the valve is closed” and “improvement of slidability when the ball valve body is rotated”), Local wear at the contact portion between the valve body and the seat member can be suppressed, and high reliability can be obtained over a long period of time.

[Means of claim 2]
Here, when the sheet surface is increased inward, it is conceivable to reduce the inner diameter of the sheet member and increase the width of the sheet surface over the entire circumference.
However, if the inner diameter dimension of the sheet member is reduced, the diameter of the passage formed inside the sheet member is reduced, leading to an increase in pressure loss with respect to the fluid.

Therefore, according to the second aspect of the present invention, a convex portion protruding in the inner diameter direction of the sheet member is provided in a part of the sheet member, and a part of the sheet surface is bulged in the inner diameter direction.
As described above, since the width of the sheet surface is locally expanded by the convex portion, it is possible to prevent the inner diameter of the sheet member from being reduced, and to suppress an increase in pressure loss.

[Means of claim 3]
The means of claim 3 is:
The outer diameter of the shaft is d1,
When the circumferential width of the convex portion when viewed from the fluid flow direction is d2,
d1> d2
It is provided in the relationship.
By providing in this way,
(I) When viewed from the fluid flow direction, all of the convex portions can be accommodated within the projection range of the shaft.
(Ii) Alternatively, when viewed from the fluid flow direction, many portions of the convex portion can be accommodated within the projection range of the shaft.

Thereby, even if a convex part is provided in the inner diameter direction of the sheet member, an increase in pressure loss due to the convex part can be suppressed by overlapping the convex part and the projection range of the shaft.
That is, the butterfly valve according to claim 3 suppresses the increase in pressure loss (or maintains the same pressure loss as in the prior art) and lowers the surface pressure of the contact portion between the ball valve body and the seat member. The occurrence of local wear can be prevented.

[Means of claim 4]
The butterfly valve according to claim 4 provides a gap between the seat member and the inner wall of the valve housing in the radial direction, and arranges a radial support seal in the gap to seal the gap and It is provided so that it can be displaced.
Thus, the seat member is supported by the radial support seal so as to be displaceable in the radial direction, and the seat surface is pressed against the ball surface by the surface pressure generating means, thereby aligning the seat surface and the ball surface. .
For this reason, when the valve is closed, the seat surface and the ball surface can be made to coincide with each other, and fluid leakage when fully closed can be reliably prevented.

(A) Explanatory drawing which shows the contact part of the ball | bowl surface and seat surface in a state with a large opening degree, (b) It is a graph which shows the relationship between a valve opening degree and a surface pressure (Example 1). (Example 1) which is sectional drawing of the EGR valve | bulb at the time of a full closure. It is explanatory drawing which shows the contact part of the ball | bowl surface and seat surface in a state with a large opening degree (Example 2). (Example 3) which is sectional drawing of the EGR valve | bulb at the time of a full closure.

A specific example of the present invention will be described with reference to the drawings.
EGR valve 1 (an example of a butterfly valve)
(A) a valve housing 3 that communicates an exhaust passage and an intake passage of the engine and forms an EGR passage 2 (an example of a fluid passage) in which exhaust gas can pass as EGR gas;
(B) a ball valve body 4 which is disposed in the EGR flow path 2 and has a ball surface 4a which is formed of a part of a spherical surface and bulges outward;
(C) a sheet member 5 having an annular seat surface 5a that is formed of a part of a spherical surface and has a concave curvature with the same curvature as the ball surface 4a;
(D) a surface pressure generating means 6 that applies a biasing force toward the ball valve body 4 to the seat member 5 to press the seat surface 5a toward the ball surface 4a;
(E) A radial support seal that is disposed in a radial gap between the seat member 5 and the inner wall of the valve housing 3 and seals the gap over the entire circumference and supports the seat member 5 so as to be displaceable in the radial direction. 7 and
(F) a shaft 8 that is rotatably supported by the valve housing 3 and drives the ball valve element 4 to rotate within the EGR flow path 2;
It comprises.

The sheet member 5 includes a convex portion 9 that locally projects from a part of the sheet member 5. And this convex part 9 expands locally the width | variety of the seat surface 5a in "the site | part which slide-contacts with the ball surface 4a with the opening degree increase of the ball valve body 4" (Example 1 mentioned later). 3).
As a preferred example, the convex portion 9 is provided so as to protrude toward the inner diameter direction of the sheet member 5 and bulges a part of the sheet surface 5a toward the inner diameter direction (Example 1, which will be described later). 2).
As a more preferable form, when viewed from the fluid flow direction, at least half (preferably most) of the protrusions 9 are within the projection range of the shaft 8.
As a more preferable form, when viewed from the fluid flow direction, all of the convex portions 9 are within the projection range of the shaft 8.

Next, Embodiment 1 in which the present invention is applied to an EGR valve 1 of an EGR device mounted on a vehicle engine will be described with reference to FIGS. In the following embodiments, the same reference numerals as those in the above-mentioned [Mode for Carrying Out the Invention] denote the same functional objects.
[Description of EGR device]
The EGR device returns part of the exhaust gas discharged from the engine to the intake side of the engine as EGR gas, thereby mixing EGR gas, which is non-combustible gas, into part of the intake air to suppress the combustion temperature of the engine combustion chamber, This is a well-known technique that effectively suppresses the generation of nitrogen oxides (NOx).
The EGR device includes at least an EGR passage 2 for returning a part of exhaust gas flowing through the exhaust passage to the intake passage as EGR gas, and an EGR valve 1 for adjusting the opening degree of the EGR passage 2. Is controlled by an ECU (abbreviation of engine control unit) according to the running state of the vehicle.

  The EGR valve 1 to which the present invention is applied may be a high-pressure EGR valve mounted on a high-pressure EGR device that returns EGR gas to a high negative pressure generation range in the intake passage (intake downstream of the throttle valve). Even a low-pressure EGR valve mounted on a low-pressure EGR valve that returns EGR gas to the low negative pressure generation range in the intake passage (intake upstream of the throttle valve: for example, upstream of the intake of the compressor if the vehicle is equipped with a turbocharger) good.

Next, the overall structure of the EGR valve 1 will be described with reference to FIG.
In the following description, the upper side in FIG. 2 is referred to as the upper side, and the lower side in the figure is referred to as the lower side. However, the upper and lower directions are directions for explaining the embodiment and are not limited.
In the following, an EGR cooler for cooling the temperature of the EGR gas is provided in the EGR flow path 2 upstream of the EGR gas in the EGR valve 1, and the EGR gas whose temperature is lowered is supplied to the EGR valve 1. Although the material of a member is demonstrated on the assumption, these materials are also examples and are not limited. That is, the materials and the like described below are specific examples and can be changed as appropriate. Of course, the present invention may be applied to an EGR valve to which a high-temperature EGR gas is supplied by changing the materials and the like. Needless to say.

The EGR valve 1 includes a valve housing 3 in which an EGR flow path 2 is formed, a ball valve body 4 and a seat member 5 disposed in the EGR flow path 2, a shaft 8 to which the ball valve body 4 is fixed, a valve housing 3 An electric actuator 11 that rotationally drives the ball valve body 4 via the shaft 8 from the outside, and a rotation sensor 12 that detects the rotation angle of the ball valve body 4 (angle of the EGR valve 1) via the shaft 8, A surface pressure generating means 6 acting on the sheet member 5 and a radial support seal 7 are provided.
Below, the said structure is demonstrated sequentially.

The valve housing 3 is formed of, for example, an aluminum alloy and is provided by a die-cast molding technique or the like, and an EGR passage 2 penetrating in the left-right direction in FIG. 2 is formed inside the valve housing 3.
In addition, the member (for example, stainless steel etc.) excellent in heat resistance and corrosion resistance may be provided in the inner wall of the EGR flow path 2 through which EGR gas flows.

The ball valve body 4 adjusts the amount of EGR gas returned to the intake passage by changing the passage area of the EGR passage 2 by adjusting the opening degree of the opening of the seat member 5 (inside the seat member 5). The valve body to perform.
The ball valve body 4 has a substantially disc shape, and one surface thereof coincides with a flat portion formed on the side surface of the shaft 8 (more specifically, the ball valve body 4 is viewed from the side surface direction of the shaft 8. In the state where the center of the body 4 and the center of the shaft 8 substantially coincide with each other), it is fixed to the side surface of the shaft 8 by a coupling means such as a screw 13.

The ball valve body 4 is made of, for example, a metal excellent in corrosion resistance and wear resistance such as stainless steel. In addition, the material of the ball valve body 4 is not limited, and may be provided by, for example, a hard resin material having excellent heat resistance, corrosion resistance, and wear resistance.
The outer peripheral edge of the ball valve body 4 is a ball surface 4a composed of a part of a spherical surface bulging outward, and the center of the ball surface 4a (the central point of the spherical surface forming the ball surface 4a) is It is provided in line with the shaft core. That is, in this embodiment, the center of the ball surface 4a and the shaft core of the shaft 8 are provided without being eccentric.

The seat member 5 has a substantially cylindrical shape that is short in the axial direction (left-right direction in FIG. 2), and is disposed in the EGR flow path 2 upstream of the EGR gas from the ball valve body 4.
The sheet member 5 is provided by, for example, a hard resin material (for example, a fluorine resin, a nylon resin, or the like) that is excellent in heat resistance, corrosion resistance, and wear resistance. In addition, the material of the sheet member 5 is not limited, For example, you may provide with the metal excellent in corrosion resistance and abrasion resistance, such as stainless steel.

The opening on the downstream side of the EGR gas in the seat member 5 is opened and closed by the above-described ball valve body 4, and the ball valve body 4 is in contact with the ball surface 4a of the ball valve body 4 when the valve is closed. An annular sheet surface 5a that is in contact with the entire circumference is formed.
The seat surface 5a is an annular valve seat constituted by a part of a concave spherical surface, and the spherical surface of the seat surface 5a has the same curvature as the spherical surface of the ball surface 4a. Specifically, the center of the seat surface 5a (the center point of the spherical surface forming the seat surface 5a) is provided on the downstream side of the EGR gas from the seat member 5 and on the extension of the central axis of the cylinder forming the seat member 5. Is.
In addition, the convex part 9 provided in the sheet | seat member 5 is mentioned later.

On the other hand, the seat member 5 is pressed toward the ball valve body 4 by the surface pressure generating means 6.
The surface pressure generating means 6 applies a biasing force toward the downstream side of the EGR gas to the seat member 5 to press the seat surface 5a toward the ball surface 4a, and sets the set load when the valve is closed. It is. The surface pressure generating means 6 is axially compressed between the ring plug 14 fixed to the upstream end of the EGR flow path 2 in the valve housing 3 and the upstream end surface of the EGR gas in the seat member 5. It is arranged with.

An example of the specific surface pressure generating means 6 will be disclosed. The surface pressure generating means 6 of this embodiment is a metal wave washer or a disc spring having a ring shape with the same diameter as the sheet member 5. The plug 14 and the seat member 5 are mounted in a compressed state.
On the other hand, the ring plug 14 is a metal plate such as aluminum having a ring disk shape, and after being press-fitted inside the upstream end of the EGR flow path 2 in the valve housing 3, a part of the valve housing 3 is caulked and deformed. (Plastic deformation) and fixed to the valve housing 3.

The sheet member 5 is supported so as to be movable within a predetermined radial range.
Specifically, the maximum outer diameter of the seat member 5 is smaller than the inner wall of the valve housing 3 that houses the seat member 5, and there is a gap between the seat member 5 and the inner wall of the valve housing 3 in the radial direction. Are spaced apart.
A radial support seal 7 is disposed between the seat member 5 and the inner wall of the valve housing 3. The radial support seal 7 seals the gap and the seat member 5 in the radial direction. It is supported so as to be movable within a predetermined range.

  The radial support seal 7 is an annular lip seal mounted inside a wide annular groove formed on the outer peripheral surface of the sheet member 5, and has excellent heat resistance, corrosion resistance, and wear resistance, for example. It is made of an elastically deformable resin material (for example, rubber or nylon). More specifically, the radial support seal 7 of this embodiment includes an inner peripheral lip portion that always contacts the sheet member 5 and an outer peripheral lip portion that has a restoring force radially outward with respect to the inner peripheral lip portion. The lip seal has a substantially cross-section of “L-shaped”, “C-shaped”, “C-shaped” and the like. Of course, these are only examples, and other members such as an O-ring may be used.

  By disposing such a radial support seal 7 in the radial gap between the seat member 5 and the inner wall of the valve housing 3, the radial gap between the seat member 5 and the inner wall of the valve housing 3 is arranged around the entire circumference. The seat member 5 can be supported so as to be displaceable in the radial direction with respect to the inner wall of the valve housing 3.

The shaft 8 is a cylindrical rod-like body that rotatably supports the ball valve body 4 in the EGR flow path 2, and the mounting surface of the ball valve body 4 is cut into a flat surface, and the side surface opposite to the flat surface. Also, a plane for seating the head such as the screw 13 is formed by cutting.
The shaft 8 extends in a direction orthogonal to the EGR flow path 2 (vertical direction in FIG. 2), and is rotatable with respect to the valve housing 3 by bearings 15 disposed above and below the EGR flow path 2. It is supported.
In FIG. 2, a rolling bearing (specifically, a ball bearing) is used as a specific example of the upper bearing 15, and a rolling sliding ring (specifically, a metal bearing) is specified as a specific example of the lower bearing 15. Although the example used is shown, the usage example of the bearing shown in FIG. 2 is an example and is not limited.

The electric actuator 11 is disposed in a space formed by the valve housing 3 and a cover 16 fixed to the upper portion of the valve housing 3 and rotationally drives the shaft 8. And a speed reduction mechanism for increasing the output torque of the electric motor.
For example, the electric motor uses a DC motor capable of controlling the rotation angle according to the energization amount, but the type of the electric motor is not limited.
The reduction mechanism combines a plurality of gears to reduce the rotation of the electric motor and transmit it to the shaft 8, and is fixed to the upper end of the shaft 8 at the center of rotation of the final gear 17.

In this embodiment, an example in which a speed reduction mechanism is used as an example of the electric actuator 11 is shown, but a direct drive type in which the shaft 8 is directly driven by an electric motor may be used.
Further, in FIG. 2, reference numeral 18 provided between the final gear 17 and the valve housing 3 is a return spring that returns the ball valve body 4 and the shaft 8 to the valve closing position (initial position: opening degree 0).

The rotation sensor 12 detects the opening degree of the shaft 8 and the ball valve body 4 and outputs it to the ECU. The ECU detects the target opening degree that is calculated according to the driving state and the actual opening detected by the rotation sensor 12. The energization value of the electric motor is feedback-controlled so that the degree matches.
As a configuration of the rotation sensor 12, a non-contact sensor is used in this embodiment. Specifically, the magnetic flux generating means 19 (using a permanent magnet or the like) assembled to the final gear 17 (rotating body that rotates integrally with the shaft 8), and the passing magnetic flux disposed inside the magnetic flux generating means 19 The Hall IC 20 generates an output signal corresponding to the signal, and the Hall IC 20 is supported by a cover 16 (fixing member).
Note that the configuration of the rotation sensor 12 is not limited to that described above, but may have another structure such as a contact-type potentiometer. Further, the present invention is not limited to the EGR valve 1 using the rotation sensor 12, and the present invention is applied to the EGR valve 1 in which the ECU feed-forward-controls the opening degree of the shaft 8 and the ball valve body 4 without using the rotation sensor 12. It may be applied.

[Background Art of Example 1]
When the width of the seat surface 5a is provided at a constant width over the entire circumference, as in the prior art, the ball surface 4a of the ball valve body 4 and the seat member are increased as the opening of the ball valve body 4 increases. 5, the contact area with the seat surface 5 a is reduced, and as shown by the solid line B in FIG. 1B, the contact pressure between the ball valve body 4 and the seat member 5 increases as the opening degree increases.
As a result, local wear may occur at the contact portion between the ball valve body 4 and the seat member 5 due to long-term use, and EGR gas may leak from the worn portion when fully closed.

Therefore, in order to suppress an increase in surface pressure, it is conceivable to reduce the inner diameter of the sheet member 5 and increase the width of the sheet surface 5a over the entire circumference.
However, if the inner diameter dimension of the sheet member 5 is reduced, the pressure loss of the EGR gas flowing in the sheet member 5 increases, and the supply of EGR gas becomes insufficient in an operation state where a large amount of EGR gas is required.
In order to avoid this problem (increase in pressure loss), it is conceivable to increase the diameter of the seat member 5, but in that case, the EGR valve 1 is increased in size.

  In addition, in the solid line B of FIG.1 (b), it is acting on the sheet | seat member 5 that a surface pressure falls temporarily in the predetermined opening range (opening range between 10 degrees of opening degrees-20 degrees). This is because the pressure of the EGR gas that has been released escapes downstream.

[Feature Technology 1 of Example 1]
The EGR valve 1 of the first embodiment employs the following technical means in order to solve the problems in the “background art of the first embodiment”.
FIG. 1 (a) is not a view as it is, but is a view for explaining a part of the sheet surface. The seat surface 5a is shown as “a portion with a large number of points”, and the ball surface. A contact portion α between 4a and the seat surface 5a is shown as “a hatched portion”.

In the EGR valve 1 according to the first embodiment, a convex portion 9 is provided on the seat member 5, and the convex portion 9 locally expands the width of the seat surface 5 a that is in sliding contact with the ball surface 4 a, so The increase of the is suppressed.
Specifically, the convex portion 9 in this embodiment is provided so as to protrude toward the inner diameter direction of the sheet member 5, and the width of the sheet surface 5a is locally bulged by the convex portion 9 toward the inner diameter direction. To do.

More specifically, the EGR valve 1 of this embodiment has a maximum opening of 70 ° when the opening when the valve is closed is 0 °. The opening degree is controlled in the range from 0 ° to the maximum opening degree of 70 °.
When the seat member 5 and the ball valve body 4 are viewed from the upstream side of the EGR gas, the contact point α between the ball surface 4a and the seat surface 5a at the maximum opening (opening 70 °) is shown in FIG. As shown, it exists in the vicinity of the upper and lower central axes of the sheet member 5 along the vertical direction of the shaft 8.
That is, when the present invention is not applied, the portion where the surface pressure is highest in the sheet surface 5 a exists near the upper and lower centers of the sheet member 5.

Therefore, in this embodiment, when the sheet member 5 is viewed from the upstream side of the EGR gas, as shown in FIG. 1A, the convex portion 9 is arranged along the center line in the vertical direction of the sheet member 5. It is provided for
For this reason, when the sheet member 5 is viewed from the upstream side of the EGR gas, the portion where the width of the sheet surface 5a is locally expanded by the convex portion 9 is also shown in FIG. It bulges out along the center line.

Specifically, when the convex portion 9 of this embodiment is viewed from the upstream side of the EGR gas, as shown in FIG. 1A, the top of the bulge of the convex portion 9 is in the upper and lower center lines of the sheet member 5. The projections 9 are substantially coincident and all or most of the projections 9 are provided within the projection range of the shaft 8.
This will be specifically described (all or most of the convex portions 9 are within the projection range of the shaft 8).

In this example,
The outer diameter of the shaft 8 is d1,
The circumferential width of the convex portion 9 when the sheet member 5 is viewed from the upstream side of the EGR gas is d2,
If
The relationship is d1> d2.
Because of this relationship (d1> d2) and the maximum opening of the ball valve body being 70 °, “all of the convex portions 9” viewed from the upstream side of the EGR gas, or “most of the convex portions 9 (for example, , 80% or more of the area of the convex portion 9 as viewed from the flow direction of the EGR gas) ”can be within the projection range of the shaft 8.

(Effect 1 of Example 1)
As described above, the EGR valve 1 of the first embodiment is provided with the convex portion 9 on the seat member 5, and the convex portion 9 locally expands the width of the seat surface 5a that is in sliding contact with the ball surface 4a. It suppresses the increase in surface pressure associated with the rise.
Thereby, as shown by the solid line A in FIG. 1B, the surface pressure between the ball surface 4a and the seat surface 5a is changed from the fully closed state (opening degree 0 °) to the maximum opening degree (opening degree 70 °). In this range, the pressure can be kept lower than a preset allowable surface pressure.

For this reason, in addition to the effect of using the “ball valve type” for the EGR valve 1 (that is, “ensurement of sealing performance when the valve is closed” and “improvement of sliding performance when the ball valve body 4 is rotated”), Even if used, the local wear at the contact portion between the ball valve body 4 and the seat member 5 can be suppressed.
That is, even if it is used for a long period of time, the occurrence of EGR gas leakage due to local wear when the valve is closed can be eliminated, and the reliability of the EGR valve 1 can be improved.

  In addition, in the solid line A of FIG.1 (b), it is (i) the sheet | seat member 5 that a surface pressure falls greatly in a predetermined opening range (opening range between 10 degrees of opening degrees-20 degrees). This is due to the fact that the pressure of the EGR gas that has acted escapes to the downstream side, and (ii) the surface pressure decreases due to the increase in the sheet surface 5a by the convex portion 9.

(Effect 2 of Example 1)
As described above, the EGR valve 1 according to the first embodiment has the convex portion 9 viewed from the upstream side of the EGR gas because the relationship of d1> d2 and the maximum opening of the ball valve body 4 are 70 °. Or most of the convex portion 9 falls within the projection range of the shaft 8.
Thereby, even if the convex part 9 is provided in the inner diameter direction of the sheet member 5 for the purpose of suppressing local wear, the convex part 9 overlaps with the shaft 8, whereby an increase in pressure loss due to the convex part 9 can be suppressed. That is, an increase in pressure loss due to the convex portion 9 can be suppressed, the contact surface pressure between the ball valve body 4 and the seat member 5 can be lowered, and local wear can be prevented.
Thus, even if the convex part 9 is provided, pressure loss does not occur in the EGR valve 1, so that it is the same size as the conventional one, local wear can be suppressed, and reliability can be improved.

(Effect 3 of Example 1)
The seat member 5 of the first embodiment is pressed against the ball valve body 4 by the surface pressure generating means 6 and supported by the radial support seal 7 so as to be movable within a predetermined radial range.
Since the seat surface 5a and the ball surface 4a are aligned by the surface pressure generating means 6 and the radial support seal 7, the seat surface 5a and the ball surface 4a can be reliably matched when the valve is closed, EGR gas leakage when fully closed can be reliably prevented.

A second embodiment will be described with reference to FIG. In the following embodiments, the same reference numerals as those in the first embodiment denote the same functional objects.
In the first embodiment, the example in which the present invention is applied to the EGR valve 1 in which the maximum opening degree of the ball valve body 4 is 70 ° is shown.
On the other hand, in the second embodiment, the present invention is applied to the EGR valve 1 in which the maximum opening degree of the ball valve body 4 is 90 °.

When the opening degree exceeds 70 °, the contact portion α between the ball surface 4a and the seat surface 5a does not fall within the projection range of the shaft 8 when viewed from the upstream side of the EGR gas.
Therefore, in the second embodiment, as shown in FIG. 3, the convex portion 9 is provided outside the projection range of the shaft 8 as viewed from the upstream side of the EGR gas, and the maximum opening degree of the ball valve body 4 is 90 °. Even if it exists, it suppresses an increase in surface pressure.

In Example 2, as seen from the upstream side of the EGR gas, most of the convex portions 9 protrude outside the projection range of the shaft 8.
However, since the surface pressure is lowered by the convex portion 9 provided in a part of the sheet member 5, "the inner diameter of the sheet member 5 is reduced" to increase the width of the sheet surface 5a over the entire circumference. As compared to “case”, occurrence of pressure loss can be suppressed to a small value.
That is, the EGR valve 1 according to the second embodiment can suppress the pressure loss and prevent the occurrence of local wear compared to the case where the inner diameter of the seat member 5 is reduced.

Embodiment 3 will be described with reference to FIG.
In the first and second embodiments, the example in which the convex portion 9 is protruded toward the inner diameter direction of the sheet member 5 is shown.
On the other hand, in Example 3, as shown in FIG. 4, the convex portion 9 is projected toward the side of the sheet member 5 close to the shaft 8 (downstream side of the EGR gas). In this way, by projecting the convex portion 9 toward the side closer to the shaft 8, a part of the sheet surface 5a can be bulged.
As a result, as in the first and second embodiments, the seat surface 5a can be locally increased to suppress an increase in surface pressure, and the occurrence of local wear can be prevented.

  In addition, you may control the surface pressure value with respect to an opening degree, combining this Example 3 with the said Example 1,2. In this manner, by projecting the convex portion 9 in both the “inner diameter direction” and the “side closer to the shaft 8”, the amount of projection of the convex portion 9 can be suppressed, and an increase in surface pressure can be suppressed.

In the above embodiment, the example in which the present invention is applied to the EGR valve 1 has been shown. However, the fluid is not limited to the exhaust gas, and other fluid flow and pressure adjustments can be performed. The present invention may be applied to a butterfly valve.
In the above embodiment, an example in which “the center of the ball surface 4a (the center point of the spherical surface)” and “the axial center of the shaft 8” are provided is shown, but “the center of the ball surface 4a” and “the shaft 8”. The present invention may be applied to a “ball valve” of “eccentric type” in which a small amount of the “core shaft” is eccentric.

1 EGR valve (butterfly valve)
3 Valve housing 4 Ball valve body 4a Ball surface 5 Seat member 5a Seat surface 6 Surface pressure generating means 7 Radial support seal 8 Shaft 9 Convex portion

Claims (4)

A ball valve body (4) having a ball surface (4a) formed of a part of a spherical surface and bulging outward;
A sheet member (5) having an annular seat surface (5a) that is formed of a part of a spherical surface and has a concave curvature matching the ball surface (4a);
A surface pressure generating means (6) for applying a biasing force toward the ball valve body (4) to the seat member (5) to press the seat surface (5a) toward the ball surface (4a);
A shaft (8) for driving the ball valve body (4) within a predetermined rotation range;
In the butterfly valve (1) comprising at least
The sheet member (5) includes a convex portion (9) protruding locally at a part of the sheet member (5),
This convex part (9) expands the width | variety of the said seat surface (5a) locally in the site | part which slidably contacts with the said ball | bowl surface (4a) with the opening degree increase of the said ball valve body (4). And butterfly valve. The butterfly valve (1) according to claim 1,
The convex portion (9) is provided to protrude toward the inner diameter direction of the sheet member (5),
A butterfly valve characterized in that a part of the seat surface (5a) bulges toward the inner diameter direction of the seat surface (5a) by the convex portion (9). The butterfly valve (1) according to claim 2,
The outer diameter of the shaft (8) is d1,
When the circumferential width of the convex portion (9) when the sheet member (5) is viewed from the fluid flow direction is d2,
d1> d2
A butterfly valve characterized by being provided in the relationship. In the butterfly valve (1) according to any one of claims 1 to 3,
The seat member (5) is disposed with a gap between the inner wall of the valve housing (3) that houses the seat member (5) in a radial direction,
In the radial gap between the seat member (5) and the inner wall of the valve housing (3), the radial gap is sealed over the entire circumference and against the inner wall of the valve housing (3). A butterfly valve characterized in that a radial support seal (7) is provided to support the seat member (5) so as to be displaceable in the radial direction.

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