JP2015113782A - Valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of a twisting phenomenon in a flap-type valve device.SOLUTION: A valve device is equipped with a valve body 9 which has a blocking surface 13 for blocking an opening 11 by being seated at a valve seat 12 formed at a peripheral edge of the opening 11, at a tip end; an arm 10 for holding the valve body 9 at one end, swinging around a predetermined rotation center A, and makes the valve body 9 open/close the opening; and a pressing surface 27 provided on the arm 10, and pressing the valve body 9 toward the valve seat 12 at the time of valve-closing when the valve body 9 blocks the opening 11. The valve body 9, on the opposite side of the blocking surface 13, has a tapered surface 19 made from a conical surface decreasing a diameter toward a rear end, and the pressing surface 27 is formed to be a surface which surface-contacts with the tapered surface 19. Therefore, as compared with a case that the pressing surface 27 is a plane surface parallel with the blocking surface 13, even if an arm tilting angle θ is less than 45°, a twisting phenomenon is less likely to occur.

Description

  The present invention relates to a valve device used as, for example, a waste gate valve.

Conventionally, a flap type valve device is known as a valve device used as a waste gate valve (for example, Patent Documents 1 and 2).
The waste gate valve is a valve that opens and closes between an exhaust gas inlet channel that introduces exhaust gas into the turbine and a bypass channel that bypasses the exhaust gas from the turbine, and the exhaust gas inlet channel and the bypass channel The opening formed in the partition between is opened and closed.

As shown in FIG. 7, a flap-type valve device 100 includes a valve body 101, an arm 102 that holds the valve body 101 at one end, swings around a predetermined rotation center A, and an actuator that drives the arm 102. Is provided.
The valve body 101 has a closing surface 105 at the tip for closing the opening 103 by being seated on a valve seat 104 formed at the periphery of the opening 103. As the arm 102 swings, the valve body 101 moves to open and close the opening 103.

  In such a valve, if an attempt is made to increase the closing load due to the valve body when the valve is closed, the normal line H at the center B of the closing surface 105 and the center B of the closing surface 105 and the rotation center A are connected. It is necessary to reduce an angle θ formed with the straight line J (hereinafter, this angle is referred to as an arm inclination angle θ).

That is, in the plan view viewed from the center of rotation, when the direction in which the straight line J extends is the y ′ direction and the direction perpendicular to this direction is the x ′ direction, the balance in the x ′ direction is the rotational torque in the closing direction. Tin, where L is the distance between points AB, and F is the normal drag received by the closing surface,
Tin / L = Fsinθ + μFcosθ
(Μ is the coefficient of friction).

Therefore,
F = Tin / {L (sin θ + μ cos θ)}
It becomes.
When F is a dead-end load and μ is a general friction coefficient in metal friction, F is increased if θ is decreased.

In particular, if the arm inclination angle θ is less than 45 °, the closing load increases, and the leakage flow rate when the valve is closed is reduced.
However, when the arm inclination angle θ is less than 45 °, there arises a problem of “squeezing phenomenon” described below.

The twisting phenomenon is a state in which the arm 102 and the valve body 101 are sandwiched between the point A and the valve seat 104 at the valve closing position even when the rotational torque is not applied. The state which the valve body 101 maintains the state which closed the opening 103 by the friction with the valve body 101 and the valve seat 104 which generate | occur | produce by the elastic force of this.
In other words, if a twisting phenomenon occurs after the valve is closed, a force is applied in the valve closing direction even when no rotational torque is applied in the valve closing direction. Will be necessary.

In the plan view seen from the center of rotation shown in FIG. 8, the direction in which the normal line H extends is the y direction, the direction perpendicular to this direction is the x direction, and acts on the valve seat 104 by the elastic force of the arm 102 and the valve body 101. If the force is f,
fsinθ <μfcosθ
If is established, a rotational torque is generated in the closing direction, and a twisting phenomenon occurs.

In other words,
tanθ <μ
It becomes.
Generally, since the friction coefficient of metal is 1 or less, there is a possibility that a “squeezing phenomenon” occurs when the arm inclination angle θ is less than 45 °.

  In the valve devices described in Patent Documents 1 and 2, the arm inclination angle θ is approximately 90 °. For this reason, the twisting phenomenon is unlikely to occur, and no countermeasures against the twisting phenomenon are disclosed.

Special table 2013-519813 gazette Special table 2010-512482 gazette

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to suppress the occurrence of a twisting phenomenon in a flap type valve device.

The present invention is a flap-type valve device that opens and closes an opening formed in a partition partitioning two spaces to communicate and close the two spaces.
The valve device includes a valve body, an arm, and a pressing surface.
The valve body has a closing surface at the tip which closes the opening by sitting on a valve seat formed at the periphery of the opening.
The arm holds the valve body at one end and swings around a predetermined rotation center to open and close the opening of the valve body.
The pressing surface is a surface that is provided on the arm and presses the valve body toward the valve seat when the valve body closes the opening.

  And the valve body has a tapered surface made of a conical surface or a polygonal pyramid surface whose diameter decreases toward the rear end on the opposite side of the closed surface, and the pressing surface is in surface contact with the tapered surface of the valve body. A surface, that is, a tapered surface.

  According to this, as compared with the case where the pressing surface is a plane parallel to the closing surface, even when the arm inclination angle θ is less than 45 °, the twisting phenomenon is less likely to occur.

1 is an overall configuration diagram including a partial cross-sectional view of a valve device (Example 1). It is a block diagram of the principal part of the supercharging system to which the valve apparatus was applied (Example 1). (A)-(c) is explanatory drawing explaining the operation | movement from a valve closing state to a valve opening state (Example 1). It is explanatory drawing explaining the conditions of the twist phenomenon generation | occurrence | production in a comparative example. It is explanatory drawing explaining the conditions of the twist phenomenon generation | occurrence | production in Example 1. FIG. (Example 2) which is a whole block diagram including the fragmentary sectional view of a valve apparatus. It is explanatory drawing explaining the deadline load of a valve apparatus (conventional example). It is explanatory drawing explaining a twist phenomenon (conventional example).

  The mode for carrying out the present invention will be described in detail with reference to the following examples.

[Example 1]
[Configuration of Example 1]
The structure of Example 1 is demonstrated using FIGS. 1-3.
The valve device of the present invention is a waste gate valve 1 mounted on a supercharging system having a turbocharger that supercharges intake gas using the pressure of exhaust gas of an internal combustion engine.

  The supercharging system is installed in a compressor (not shown) provided in the middle of the intake pipe of the engine, a turbine (not shown) provided in the middle of the exhaust pipe of the engine, and a housing of the turbine. The waste gate valve 1 and an actuator (not shown) for driving the waste gate valve 1 are provided.

The turbine housing is formed of a heat-resistant metal (for example, a heat-resistant aluminum alloy or heat-resistant steel).
The turbine housing has an exhaust gas passage communicating with an exhaust passage of the engine, a partition wall 4 that partitions the exhaust gas passage into two first and second exhaust gas passages 2 and 3 disposed adjacent to each other, And the communication hole 5 which connects the 1st exhaust gas flow path 2 and the 2nd exhaust gas flow path 3 is provided (refer FIG. 2).

  Here, the first exhaust gas passage 2 is an exhaust gas inlet passage through which exhaust gas is introduced into the turbine. The second exhaust gas flow path 3 is a bypass flow path for bypassing the exhaust gas from the turbine. The communication hole 5 is a communication passage that penetrates the partition wall 4 in the plate thickness direction so as to communicate between the two spaces (the first exhaust gas passage 2 and the second exhaust gas passage 3). That is.

The waste gate valve 1 is disposed in the second exhaust gas passage 3 and opens and closes the communication hole 5.
When the turbocharger supercharging pressure is less than the set value, the communication hole 5 is closed, and the exhaust gas discharged from the engine flows into the turbocharger turbine housing through the first exhaust gas passage 2. Let The exhaust gas that has flowed into the first exhaust gas flow path 2 is driven to rotate outside the turbine wheel, and is then discharged to the outside through an exhaust gas outlet flow path (not shown).
When the turbocharger boost pressure rises to a set value or more, the communication hole 5 is opened, and a part of the exhaust gas flowing into the first exhaust gas flow path 2 is made to flow into the communication hole 5 and the second exhaust gas flow. It is detoured from the turbine via the passage 3 and escapes to the exhaust gas outlet passage. Thereby, the supercharging pressure of the turbocharger is suppressed to a set value or less.

The waste gate valve 1 includes a valve body 9 and an arm 10 described below.
The valve body 9 is made of a heat-resistant metal (for example, a heat-resistant aluminum alloy or heat-resistant steel), and is seated on a valve seat 12 formed at the periphery of the opening 11 on the second exhaust gas flow path 3 side of the communication hole 5. Thus, the front end has a closing surface 13 for closing the opening 11.
Specifically, the valve body 9 includes a valve portion 15 having a closing surface 13 at the tip, a tapered portion 16 formed on the rear end side of the valve portion 15, and a column formed on the rear end side of the tapered portion 16. Part 17 and a flange part 18 formed on the rear end side of the pillar part 17.

The valve portion 15 has a disk shape, and a front end surface (surface on the valve seat 12 side) is a closed surface 13. In this embodiment, the closing surface 13 and the seating surface of the valve seat 12 are flat with each other.
The tapered portion 16 has a tapered surface 19 formed of a conical surface whose diameter decreases toward the rear end on the rear end side of the valve portion 15. The tapered surface 19 extends from the front end side to the rear end side, and is inclined at a predetermined inclination angle φ. The inclination angle φ represents the degree of inclination of the tapered surface 19 with respect to the closing surface 13 and is an angle formed by the closing surface 13 and the tapered surface 19.

  The column portion 17 is provided in a columnar shape having the same diameter as the minimum diameter portion of the tapered portion 16 or a smaller diameter. In the present embodiment, the tapered portion 16 has a truncated cone shape, and a column portion 17 is provided continuously to the rear end side of the top portion 16a so as to have the same diameter as the circle of the top portion 16a.

  The flange portion 18 is provided at the rear end of the column portion 17 and is provided in a flange shape having a diameter larger than that of the column portion 17. For example, you may provide by fixing a washer to the rear end of the pillar part 17 by press injection.

The arm 10 is made of a heat-resistant metal (for example, a heat-resistant aluminum alloy or heat-resistant steel) having a lower elastic coefficient than that of the valve body 9.
The arm 10 includes a shaft 21 extending in a direction perpendicular to the flow path center line direction of the communication hole 4 (flow direction of exhaust gas flowing through the communication hole 4 (exhaust flow direction)) (depth direction in the drawing). The arm body 22 is connected to the shaft 21 and extends outward in the radial direction of the shaft 21.

The shaft 21 is rotatably supported in a bearing hole of the housing via a bearing. The rotation center of the shaft 21 is the rotation center A of the arm 10.
One end of the shaft 21 protrudes from the inside of the housing to the outside, and the output shaft of the actuator is fixed.
The valve body 9 is held at one end of the arm main body 22, and the other end of the arm main body 22 is connected to the shaft 21.
Thereby, the arm 10 rotates around the rotation center A by the driving force of the actuator, the arm main body 22 swings, and the valve body 9 rotates around the rotation center A together with the arm main body 22.

A cylindrical portion 25 for holding the valve body 9 is provided at one end of the arm 10 main body.
The cylindrical portion 25 has a cylindrical shape that surrounds the outer periphery of the column portion 17. If the same direction as the front end side of the valve body 9 is the front end side and the opposite side is the rear end side in the cylindrical axis direction of the cylindrical portion 25, the opening peripheral edge 25 a on the front end side of the cylindrical portion 25 can come into surface contact with the tapered surface 19. The opening peripheral edge 25b on the rear end side forms a facing surface that faces the flange portion 18.

Thereby, the valve part 9 is hold | maintained at the other end of an arm main body because the cylinder part 25 surrounds the pillar part 17 between the flange part 18 and the taper part 16. FIG.
When the valve body 9 and the arm 10 are closed, clearances C are provided between the inner peripheral surface of the cylindrical portion 25 and the outer peripheral surface of the column portion 17, and between the opening peripheral edge 25 b and the flange portion 18. The valve body 9 can be slightly displaced in the axial direction and the radial direction of the cylindrical portion 25.

  As shown in FIG. 1, the tapered surface of the opening peripheral edge 25 a forms a pressing surface 27 that contacts the tapered surface 19 and presses the valve body 9 toward the valve seat 12 when the valve is closed.

The rotation center A of the arm 10 is not on the normal H at the center B of the closing surface 13 but on a straight line J rotated clockwise from the normal H by a predetermined angle θ about the point B.
That is, as shown in FIG. 1, when the valve body 9 is seated and the opening 11 is closed, a straight line J connecting the center B of the closing surface 13 and the rotation center A with respect to the normal H is The arm main body 22 holds the valve element 9 with respect to the rotation center A so as to incline a predetermined angle θ clockwise in the figure. This angle θ is called an arm inclination angle.

In this embodiment, the arm inclination angle θ is less than 45 °.
Further, the inclination angle φ of the tapered surface 19 is less than 45 °.

The operation of the waste gate valve 1 will be described with reference to FIG.
When the turbocharger supercharging pressure is equal to or lower than the set value, as shown in FIG. 3A, the valve body 9 is seated on the valve seat 12 and the opening 11 is closed, that is, the communication hole 5 is closed. It has become. The arm 10 is loaded with rotational torque from the actuator in the counterclockwise direction shown in the figure, and a closing load corresponding to the rotational torque acts on the valve body 9 (see FIG. 7).

  When the turbocharger supercharging pressure rises to a set value or more, the actuator is actuated, the rotational torque from the actuator is applied to the arm 10, and the arm 10 rotates around the rotation center A in the clockwise direction in the figure. As a result, as shown in FIG. 3B, the valve body 9 rotates around the rotation center A together with the arm 10, the closing surface 13 is separated from the valve seat 12, and the opening 11 is opened. FIG. 3C is a diagram showing a state where the arm 10 is further rotated from the state of FIG.

[Effect of Example 1]
According to the present embodiment, the pressing surface 27 on which the arm 10 presses the valve body 9 is not a plane parallel to the closing surface 13 but a tapered surface 19. According to this, as compared with the case of a flat surface, even if the arm inclination angle θ is less than 45 °, the twisting phenomenon is less likely to occur.
When the arm inclination angle θ is less than 45 °, the deadline load can be increased as described with reference to FIG. However, the twisting phenomenon described with reference to FIG. 8 occurs.

As described above, the twisting phenomenon is a state in which the arm 10 and the valve body 9 are sandwiched between the rotation center A and the partition wall 4 at the valve closing position even when the rotational torque is not applied. And the state which the valve body 9 maintains the state which closed the opening 11 by the friction with the valve body 9 and the valve seat 12 which generate | occur | produces with the elastic force of the valve body 9 is said.
The effect of the present embodiment will be described in detail with reference to FIGS.

FIG. 4 shows a comparative example in which the pressing surface 27 is a plane parallel to the closing surface 13 and has a plane 29 in surface contact with the pressing surface 27 instead of the tapered surface 19.
Example 1 is shown in FIG.
Then, in each of the comparative example and the example 1, conditions for causing the twisting phenomenon are considered.

Since the elastic modulus of the arm 10 is lower than that of the valve body 9, the twisting phenomenon that occurs between the arm 10 and the valve body 9 and the valve seat 12 is equivalent to the twisting phenomenon that occurs between the valve body 9 and the arm 10. Think of it as
That is, the twist phenomenon described in FIG. 4 and FIG. 5 is a state in which the arm 10 is sandwiched between the valve body 9 and the rotation center A, and the arm 10 and the valve body generated by the elastic force of the arm 10. 9 is a state in which the arm 10 does not move and the valve body 9 maintains the state in which the opening 11 is closed due to friction with 9.

First, let us consider the conditions for occurrence of the twisting phenomenon of the comparative example.
In a plan view seen from the center of rotation, direction y ₁ direction extending the plane normal 29, the direction perpendicular to the x ₁ direction thereto.

In the comparative example, since the pressing surface 27 and the plane 29 in surface contact with the pressing surface 27 are parallel to the closing surface 13, the load received by the plane 29 from the pressing surface 27 is averagely applied to the plane 29. Therefore, the force relationship at the representative point is considered with the intersection B ₁ between the plane 29 and the normal H as the representative point.

By arm is sandwiched and elastically deformed between the point B ₁ as the center of rotation A, the force f ₁ generated by the elastic force of the arm 10 on the valve element 9 at point B ₁ is, the point B ₁ from point A Loaded in the direction of heading.

The _{y 1} direction component in the friction force _.mu.f 1 cos [theta] ₁ which is generated by a vertical effect _f 1 cos [theta] ₁ is the _{f 1} is a prying phenomenon occurs greater than _f 1 sin [theta ₁ is _{x 1} direction component of _{f 1.} That is, if tan θ ₁ <μ is satisfied, a twisting phenomenon occurs. That is, if θ _{1 is set} to 45 ° or more, the twisting phenomenon does not occur.
Note that θ ₁ is an angle formed by a straight line connecting the point A and the point B ₁ and the normal line of the plane 29.
However, when the arm inclination angle θ is 45 ° or less, it is difficult to make θ ₁ 45 ° or more.

Next, let us consider the conditions for occurrence of prying in Example 1.
In a plan view seen from the center of rotation, direction y ₂ directions normal to the tapered surface 29 extends to a direction perpendicular to the x ₂ direction thereto.

In the case of the embodiment 1, since the load tapered surface 19 receives from the pressing surface 27 it is mainly loaded on the far side of the tapered surface 19a from the center of rotation A, a point B ₂ on the tapered surface 19a as a representative point, Consider the force relationship at the representative points.

By arm is sandwiched and elastically deformed between the point B ₂ and the rotational center A, the force f ₂ generated by the elastic force of the arm 10 on the valve element 9 at point B ₁ is, from point A to point B ₂ Loaded in the direction of heading.

The frictional force _.mu.f 2 cos generated by a vertical effect _f 2 cos [theta] ₂ is _{y 2} direction component of _{f 2} is prying phenomenon occurs with greater than _f 2 sin [theta ₂ is _{x 2} direction component of _{f 2.} That is, if tan θ ₂ <μ is satisfied, a twisting phenomenon occurs. That is, if θ _{2 is set} to 45 ° or more, the twisting phenomenon does not occur.

Θ ₂ is an angle formed by a straight line connecting the point A and the point B ₁ and the normal line of the tapered surface 19.
In this embodiment, by employing the tapered surface 19, even if the arm inclination angle theta is 45 ° or less, which is easy to the theta ₂ to 45 ° or more. That is, since the inclination angle φ of the tapered surface 19 can be added as compared with θ _{1 of} the comparative example, θ ₂ of the embodiment can be increased.
Therefore, in this embodiment, it is possible to prevent the occurrence of the twisting phenomenon by avoiding the establishment of the condition for the occurrence of the twisting phenomenon.

In addition, when the circular arc surface is adopted instead of the tapered surface 19, the inclination angle φ is not constant, so that it is difficult to ensure that θ ₂ is 45 ° or more.

  In the present embodiment, the arm inclination angle θ is less than 45 °. Conventionally, if the arm inclination angle θ is less than 45 °, a twisting phenomenon is likely to occur, and therefore it may be difficult to make the arm inclination angle θ less than 45 °. However, in the present embodiment, the provision of the tapered surface 19 can suppress the occurrence of the twisting phenomenon, so that the arm inclination angle θ can be made less than 45 ° for the purpose of increasing the dead-end load.

Further, the inclination angle φ of the tapered surface 19 is less than 45 °.
According to this, when the friction is considered only by the relationship between the pressing surface 27 and the tapered surface 19, the frictional force generated between the pressing surface 27 and the tapered surface 19 becomes excessive, and the pressing surface 27 and the tapered surface 19 are tapered. The phenomenon that the surface 19 is fixed can be suppressed.

In the present embodiment, clearances C (backlash) are provided between the inner peripheral surface of the cylindrical portion 25 and the outer peripheral surface of the column portion 17 and between the opening peripheral edge 25 b and the flange portion 18.
According to this, even when the valve body 9 and the arm 10 are used in a high temperature environment such as an exhaust passage through which high temperature exhaust gas flows, deformation due to thermal distortion can be absorbed by the clearance C. .
For this reason, even when thermal distortion occurs, the opening 11 can be reliably closed by the closing surface 13 when the valve is closed.

[Example 2]
A second embodiment will be described with reference to FIG. 6 with a focus on differences from the first embodiment.
In addition, the same code | symbol as Example 1 shows the same functional thing, Comprising: The previous description is referred.
In the first embodiment, the closing surface 13 is a flat surface, and the valve seat 12 has a flat surface that comes into surface contact with the closing surface 13 when the valve is closed. In this embodiment, the closing surface 13 is a cylindrical surface or a spherical surface. The valve seat 12 has a cylindrical surface or a spherical surface that comes into surface contact with the closing surface 13 when the valve is closed.

That is, as shown in FIG. 6, the closing surface 13 of the valve body 9 is a cylindrical surface or a spherical surface that protrudes toward the distal end. The valve seat 12 has a concave surface corresponding to the closing surface 13.
The rotation center A of the arm 10 exists on a straight line J that is rotated from the normal line H around the point B by a predetermined angle θ counterclockwise in the figure. This angle θ (ie, arm inclination angle θ) is less than 45 °.

  Also in the present embodiment, the valve body 9 has the tapered surface 19 and the pressing surface 27 is in surface contact with the tapered surface 19, and the same effects as those of the first embodiment are achieved.

  In addition, if the distance in the direction perpendicular to the normal H between the rotation center A of the arm 10 and the center B of the closing surface 13 is Lx, the distance Lx can be made smaller than that in the first embodiment. In the case of the first embodiment, the distance Lx needs to be greater than the radius of the valve portion 15.

(Modification)
In the embodiment, the arm inclination angle θ is less than 45 °, but the arm inclination angle θ may be 45 ° or more. Further, the inclination angle φ of the tapered surface 19 may be 45 ° or more.
In the embodiment, the tapered surface 19 is a conical surface, but may be a polygonal pyramid surface.

DESCRIPTION OF SYMBOLS 1 Waste gate valve, 2 1st exhaust gas flow path, 2nd exhaust gas flow path, 4 Partition, 9 Valve body, 10 Arm, 11 Opening, 12 Valve seat, 13 Closing surface, 19 Tapered surface, 27 Pressing surface

Claims (6)

A flap-type valve device for communicating and closing between the two spaces (2, 3) by opening and closing an opening formed in the partition wall (4) dividing the two spaces (2, 3). ,
A valve body (9) having a closing surface (13) at the tip for closing the opening (11) by sitting on a valve seat (12) formed at the periphery of the opening (11);
An arm (10) that holds the valve body (9) at one end, swings around a predetermined rotation center A, and opens and closes the opening of the valve body (9);
A pressing surface that is provided on the arm (10) and presses the valve body (9) toward the valve seat (12) when the valve body (9) closes the opening (11). 27)
The valve body (9) has, on the opposite side of the closing surface (13), a tapered surface (19) composed of a conical surface or a polygonal pyramid surface that decreases in diameter toward the rear end,
The valve device, wherein the pressing surface (27) is formed on a surface that is in surface contact with the tapered surface (19). The valve device according to claim 1,
The angle θ formed by the normal H at the center B of the closing surface (13) when the valve is closed and the straight line connecting the center B of the closing surface (13) and the rotation center A is less than 45 °. A characteristic valve device. The valve device according to claim 1 or 2,
The valve device characterized in that the inclination angle φ of the tapered surface (19) is less than 45 °. In the valve apparatus as described in any one of Claims 1-3,
The closing surface (13) is planar;
The valve seat (12) has a flat surface that comes into surface contact with the closing surface (13) when the valve is closed. In the valve apparatus as described in any one of Claims 1-3,
The closing surface (13) is a cylindrical surface or a spherical surface;
The valve seat (12) has a cylindrical surface or a spherical surface in surface contact with the closing surface (13) when the valve is closed. In the valve apparatus as described in any one of Claims 1-4,
The valve body (9) includes a valve portion (15) having the closing surface (13), a taper portion (16) formed on the rear end side of the valve portion (15) and having the tapered surface, A column portion (17) provided on the rear end side of the taper portion (16) with the same diameter as or smaller than the minimum diameter portion of the taper portion (16), and the column at the rear end of the column portion (17). A flange portion (18) having a diameter larger than that of the portion (17),
The arm (10) has a cylindrical shape that surrounds the outer periphery of the pillar (17), the opening periphery (25a) on the front end side forms the pressing surface (27), and the opening periphery (25b) on the rear end side. A cylindrical portion (25) facing the flange portion (18);
When the valve is closed, between the flange portion (18) and the rear end of the cylindrical portion (25), and between the inner peripheral surface of the cylindrical portion (25) and the outer peripheral surface of the column portion (17). A valve device characterized in that a clearance is formed on the valve device.

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