JPH10141515A - Lift stopper for control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lift stopper for a control valve capable of forming a control valve which is simple in construction, easy in installation, low in cost, light in weight, and high in vibration resistance. SOLUTION: A lift stopper 30 is provided on the outside of a cylinder case 21 for a stem shaft 3. Thus when a plug is moved by an amount exceeding a specified limit to the cylinder case 21 side, the contact member of the lift stopper 30 is brought in contact with a lift stopper contact part 12a to prevent it from moving.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control valve lift stopper for a control valve for controlling the flow rate of fluid by opening and closing a plug by driving an operating device, which prevents the plug from rising above a certain limit when opening and closing the plug. Things.

[0002]

2. Description of the Related Art FIG. 7 is a partially sectional side view showing a conventional control valve having a lift stopper. In FIG. 7, reference numeral 1 denotes a plug as a valve for controlling a flow rate of a fluid to be passed, and 2 denotes a plug 1 A valve shaft 3 for transmitting a driving force is a stem shaft connected to the valve shaft 2 by a stem connector 4, a stem 5 is connected to the stem shaft 3, and a piston reciprocating up and down in a cylinder case 6; Case,
Reference numeral 6a denotes a lift stopper provided on the cylinder case 6, which is formed by making the inner diameter of the cylinder case 6 smaller in the upper part in the figure, larger in the lower part in the figure, and adjusting the large inner part in the lower part to the outer diameter of the piston 5. When the piston 5 rises, it comes into contact with the piston 5 to prevent the piston 5 from rising excessively.

Reference numeral 7 denotes an upper portion of the cylinder case, 8 denotes a screw screwed into the upper portion 7 of the cylinder case, 9 denotes a spring for urging the piston 5 downward in the drawing, 10 denotes a spring presser, and 11 denotes the inside of the cylinder case 6. An air inlet / outlet for taking air in and out of the space below the piston 5;
Is a yoke for connecting and fixing the cylinder case 6 and the valve box 13, 13 is a valve box, and 14 is a valve seat.

Next, the operation will be described. A downward biasing pressure is constantly applied to the upper surface of the piston 5 by a spring 9, and the downward biasing pressure applied to the piston 5 causes the plug 1 to move downward through the stem shaft 3 and the valve shaft 2. Energized, thereby closing the valve.

[0005] The lower surface of the piston 5 also has an air inlet / outlet 11.
From the compressed air, receives an upward biasing pressure due to air pressure, and this upward biasing pressure biases the plug 1 upward through the stem shaft 3 and the valve shaft 2, whereby the valve is actuated. open.

During operation of the control valve, by adjusting the air pressure supplied from the air inlet / outlet 11, the balance between the downward urging pressure by the spring 9 and the upward urging pressure by the air pressure changes. As a result, the plug 1 moves up and down to adjust the gap between the plug 1 and the valve seat 14, and the flow rate of the fluid is controlled.

In an initial state in which no air pressure is applied from the air inlet / outlet 11 and no upward urging pressure is applied, the plug 1 is completely closed by the downward urging pressure of the spring 9 and no fluid leakage occurs. Need to be. In order to generate the initial pressure on the plug 1 in this manner, the spring 9 needs to be in a state where the spring 9 is sufficiently compressed from its natural length. Is screwed down to lower the position of the spring retainer 10, and the natural length spring 9 is sufficiently compressed.

When the air pressure introduced from the air inlet / outlet 11 overcomes the elastic force of the spring 9 and raises the piston 5 too much, the plug 1 through the stem shaft 3 and the valve shaft 2
May rise excessively, and for example, the plug 1 may strongly collide with the valve box 13 and the plug 1 may drop off from the valve shaft 2, or the plug 1 and the valve box 13 may be damaged. For this reason, the above-mentioned lift stopper 6a is formed in the cylinder case 6, and when the piston 5 rises excessively, the piston 5 contacts the lift stopper 6a,
Excessive rise of the piston 5 and the plug 1 is prevented.

FIG. 8 is a side sectional view showing an upper portion of a conventional control valve having a lift stopper having another configuration. In the figure, reference numeral 15 denotes a first cylinder portion, and 16 denotes a second cylinder portion. Note that the same or corresponding portions as those shown in FIG. 7 are denoted by the same reference numerals, and redundant description will be omitted.

In the first conventional example, as shown in FIG. 7, the lift stopper 6a is formed by shaving the inner surface of the cylinder case 6 to give a step to the inner diameter. In the conventional example, a second cylinder portion 16 having a diameter larger than that of the first cylinder portion 15 is provided as a separate member, and a lift stopper is formed by adjusting the outer diameter of the piston 5 to the inner diameter of the second cylinder portion 16.

[0011]

Since the conventional lift stopper for a control valve is constructed as described above, in the first conventional example, the lift stopper 6a for preventing the piston 5 and the plug 1 from excessively rising is provided. When forming the portion which comes into contact with the piston 5 by cutting the inner diameter of the lower part of the cylinder case 6 further larger in the formation of the cylinder case, a very precise finish is required, a long time is required for the cutting operation, and the manufacturing cost is increased. Had a problem of rising.

In addition, since the thickness of the portion above the lift stopper 6a of the cylinder case 6 is inevitably increased, the weight of the actuator of the control valve itself becomes heavy, the center of gravity becomes high, and the control valve is subject to vibration. There was a problem that the structure was weak.

Further, in the second conventional example, since the first cylinder portion 15 and the second cylinder portion 16 need to be formed, the number of parts of the control valve increases and the structure becomes complicated.

Further, both prior arts have a problem that the lift position cannot be adjusted because the lift stopper is provided in the operating device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a simple structure, can be easily and inexpensively installed, and has a lightweight and vibration-resistant control valve. An object is to obtain a valve lift stopper.

Another object of the present invention is to provide a lift stopper for a control valve which can adjust the lift positions of a piston and a plug.

[0017]

A lift stopper for a control valve according to the present invention is provided on a portion of a shaft connected to a plug outside a cylinder case, and the plug moves toward the cylinder case by a predetermined limit or more. When trying to do so, a contacting member for preventing the movement by contacting a contact portion provided on the lower surface of the cylinder case or on the plug side outside of the cylinder case is provided.

In the lift stopper for a control valve according to the second aspect of the present invention, the contact member is provided so as to be movable in the axial direction of a shaft connected to the plug.

In the lift stopper for a control valve according to the third aspect of the present invention, a stem connector for connecting a pressure member side portion and a plug side portion of a shaft connected to a plug is used as a contact member.

According to a fourth aspect of the present invention, there is provided a lift stopper for a control valve, wherein a protection member is provided around the contact portion to prevent intrusion of a hand or an object from the outside.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a partial sectional view showing a control valve to which a control valve lift stopper according to a first embodiment of the present invention is applied. In the figure, reference numeral 2 denotes a valve shaft (not shown) for transmitting a driving force to a plug 1 (not shown). The stem shaft (plug-side portion), 3 is attached to the piston 5, and the stem shaft (the shaft connected to the plug, the pressure member side portion) connected to the valve shaft 2 by the stem connector 4; A piston (compression member) that reciprocates up and down in the cylinder case 21, 7 is an upper portion of the cylinder case, 8 is a screw screwed into the upper portion 7 of the cylinder case, and 9 is a piston 5.
, A spring presser 10, a spring presser 10, an air inlet / outlet 11 for taking air in and out of a space below a piston in a cylinder case 21, and a cylinder case 21 and a valve box 13 (not shown) Are connected and fixed. The above is the same as the conventional control valve shown in FIGS. 7 and 8. It should be noted that a diaphragm or the like may be used as the pressing member in addition to the piston 5.

Reference numeral 21 denotes a cylinder case provided with no lift stopper unlike the conventional example, and reference numeral 22 denotes a bonnet forming the lower lid of the cylinder case 21. Reference numeral 30 denotes a lift stopper provided on the stem shaft 3, and 12a
Is a lift stopper contact portion (contact portion) provided on the yoke 12.

The valve box 13 having the valve seat 14 is connected and fixed to the yoke 12, and the valve shaft 2 and the plug 1 are connected to the stem shaft 3 as in the conventional example. Description is omitted.

FIGS. 2A and 2B show details of the structure of the lift stopper for the control valve according to the first embodiment. FIG. 2A is a partial cross-sectional side view showing the vicinity of the lift stopper 30, and FIG. FIG. 10 is a perspective view of a stopper member 30a of FIG. In the figure, reference numeral 30a denotes a cylindrical stopper member (abutting member) having a bottom surface on which a hole through which the stem shaft 3 passes is formed.
It is fixed to the stem shaft 3 by 2. It should be noted that the stem portion 3 has a screw portion 3 that engages with the nut 31 and the nut 32.
a is formed.

Next, the operation will be described. When assembling the stopper member 30a in the lift stopper 30, first, the nut 31 is rotated and attached to a predetermined position on the stem shaft 3 before the stem connector 4 and the valve shaft 2 are attached. The stem axis 3
And tighten it with a nut 32 to fix it.
After that, the stem shaft 3 is connected to the valve shaft 2 by the stem connector 4.

Next, the normal operation of the control valve will be described. A downward biasing pressure is constantly applied to the upper surface of the piston 5 by a spring 9, and the downward biasing pressure applied to the piston 5 is transmitted through the stem shaft 3 and the valve shaft 2 to the plug 1.
Urges downwards, thereby closing the valve.
The lower surface of the piston 5 also receives an upward biasing pressure due to pneumatic pressure by flowing compressed air in and out of the air inlet / outlet 11, and the upward biasing pressure is applied to the stem shaft 3 and the valve shaft 2.
Urges the plug 1 upwardly, thereby opening the valve. During the operation of the control valve, by adjusting the air pressure supplied from the air inlet / outlet 11, the balance between the downward urging pressure by the spring 9 and the upward urging pressure by the air pressure changes. The gap between the plug 1 and the valve seat 14 is adjusted by moving the plug 1 up and down, and the flow rate of the fluid is controlled.

In an initial state in which no air pressure is applied from the air inlet / outlet 11 and no upward biasing pressure is applied, the plug 1 is completely closed by the downward biasing pressure of the spring 9 and no fluid leakage occurs. Need to be
The elastic force of the spring 9 is adjusted by tightening the screw 8 when the control valve is installed.
This is done by adjusting the position of.

When the air pressure introduced from the air inlet / outlet 11 during operation of the control valve exceeds the elastic force of the spring 9 too much and the piston 5 tries to rise excessively, the stopper member 30a of the lift stopper 30 which rises at the same time. Of the piston 5 and the plug 1 is prevented from rising excessively, and the plug 1 collides with the valve box 13 to prevent the plug 1 from rising. Can be prevented from dropping from the valve shaft 2 or damage to the plug 1, the valve box 13, and the like.

When it is desired to change the lift position of the piston 5 and the plug 1, the tightening / fixing position of the stopper member 30 a by the nut 31 and the nut 32 on the stem shaft 3 is easily changed outside the control valve. Therefore, the lift position can be easily adjusted.

In the first embodiment, since the upper wall of the cylinder case 21 does not become thick as in the first conventional example, the center of gravity of the control valve does not increase, and the lift stopper 30 is provided with the control valve. The center of gravity of the control valve can be made closer to the center, and a control valve resistant to vibration can be configured. Further, unlike the second conventional example, a large number of parts for forming a plurality of cylinder chambers are not required, and the lift stopper can be formed with a small number of parts.

As described above, according to the first embodiment, the control valve can be easily and inexpensively installed with a simple structure, and a lightweight and vibration-resistant control valve can be constructed.
A lift stopper for a control valve that can easily adjust the lift position is obtained.

Embodiment 2 FIG. FIG. 3 shows a stopper member 30 of a control valve lift stopper according to a second embodiment of the present invention.
FIG. 3B is a diagram showing details of the structure of FIG.
(B) is a side sectional view. In the drawing, reference numeral 30b denotes a stopper member (contact member) having a rectangular bottom surface and a rectangular bottom surface in which a hole through which the stem shaft 3 passes is formed. The configuration of the lift stopper 30 other than the stopper member 30b, and the configuration of the control valve other than the lift stopper 30 are the same as those in the first embodiment, and the illustration and redundant description are omitted.

Next, the operation will be described. The method of assembling the stopper member 30b in the lift stopper 30 and the operation of the control valve are the same as those in the first embodiment. In the second embodiment as well, the control valve can be easily and inexpensively installed with a simple structure. In addition, it is possible to obtain a control valve lift stopper that can constitute a lightweight and vibration-resistant control valve and that can easily adjust the lift position.

Embodiment 3 4A and 4B are diagrams showing details of the structure of a control valve lift stopper according to Embodiment 3 of the present invention, wherein FIG. 4A is a partial cross-sectional side view near the lift stopper 30, and FIG. FIG. 3C is a side view showing the shape of the stem shaft 3 in the vicinity of the lift stopper 30. In the figure, reference numeral 3b denotes a step formed by making the diameter of the upper part smaller than that of the lower part of the stem shaft 3, and reference numeral 40 denotes a disk-shaped stopper plate having a hole of a size to be locked by the step 3b. A plurality of screw holes for screwing to bolts 41 to be described later are formed at a plurality of locations around the upper portion, and are passed through the stem shaft 3 at a stage before the stem shaft 3 is attached to the piston 5, and are welded or the like. To the stem shaft 3. Reference numeral 41 denotes a bolt (abutting member) that is screwed into the plurality of screw holes formed around the upper portion of the stopper plate 40.

Next, the operation will be described. In the third embodiment, the function of the lift stopper is realized by the upper end of the bolt 41 abutting on the lift stopper abutting portion 12a, like the upper end of each stopper member in the first and second embodiments. .

When changing the lift position, each bolt 41 screwed to the stopper plate 40 can be rotated to change its height, and the lift position can be easily adjusted. The number of bolts 41 to be installed is not particularly limited as long as it is plural, but about three bolts are appropriate.

As described above, also in the third embodiment, it is possible to obtain a control valve lift stopper having the same effects as those of the above embodiments.

Embodiment 4 FIG. 5A and 5B are diagrams showing details of the structure of a lift stopper for a control valve according to Embodiment 4 of the present invention. FIG. 5A is a side sectional view near the lift stopper 30, and FIG. It is a perspective view. In the drawing, reference numeral 50 denotes a disk-shaped stopper plate attached to the step 3b of the stem shaft 3 in the same manner as in the third embodiment, and a screw for screwing with a stopper member 51 described later is formed on the outer periphery thereof. Have been. Reference numeral 51 denotes a cylindrical stopper member (abutting member) formed on the inner surface with a screw screwed with the screw on the outer periphery of the stopper plate 50, and 52 denotes an outer screw with a screw screwed on the screw on the inner surface of the stopper member 51. This is a detent ring formed on the base. The same or corresponding portions as those shown in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

Next, the operation will be described. By rotating the cylindrical stopper member 51 with respect to the stopper plate 50 fixed to the stem shaft 3, the stopper member 5 is rotated.
1 can be adjusted in the vertical direction, and the lift position can be easily adjusted. After the stopper member 51 is moved to a height suitable for a desired lift position, the rotation preventing ring 52 is tightened to the stopper plate 50 side to prevent unnecessary rotation of the stopper member 51 and fix the stopper member 51. Do.

As described above, also in the fourth embodiment, it is possible to obtain a control valve lift stopper having the same effects as those of the above embodiments.

Embodiment 5 FIG. FIG. 6 is an exploded perspective view showing the details of the structure of the control valve lift stopper according to the fifth embodiment of the present invention. In the drawing, reference numerals 4a and 4b denote connector members (contact members) of the stem connector 4, and FIG.
Reference numeral 0 denotes a bolt for tightening the space between the connector members 4a and 4b. The connector member 4a has a screw hole to be screwed with the bolt 60, and the connector member 4b has a hole for passing the bolt 60. 2 and 3 are shown in FIG.
The valve shaft and the stem shaft shown in FIG.

In the fifth embodiment, the valve shaft 2 and the stem shaft 3
Is used as a contact member, and the configuration of the connector members 4a and 4b and the bolt 60 is the same as that of a normal stem connector, and a valve is provided between the connector member 4a and the connector member 4b. The valve shaft 2 and the stem shaft 3 are connected by arranging the shaft 2 and the stem shaft 3 and tightening the bolt 60.

In the case where a lift stopper in which the stem connector 4 contacts the lift stopper contact portion 12a at the position shown in FIG. 1 is formed, the position of the stem connector 4 needs to be higher than usual. In this case, In the design of the control valve, the length of the valve shaft 2 is designed to be longer than usual, and the length of the stem shaft 3 is designed to be shorter than usual. Further, the valve shaft 2 and the stem shaft 3
The lift stopper abutting portion 12a may be provided further downward by changing the shape of the yoke 12 without changing the length of the yoke 12.

Although the stem connector 4 using two bolts 60 is shown in FIG. 6, a four or more large connector as shown in FIG. 1 may be used. Also, the stem connector 4 is formed to be vertically long,
The position of the stem connector 4 with respect to the connection position between the valve shaft 2 and the stem shaft 3 can also be adjusted up and down. In this case, the adjustment makes it possible to adjust the lift position.

As described above, according to the fifth embodiment, it is possible to provide a control valve lift stopper having the same effects as those of the above-described embodiments without requiring any additional parts.

Embodiment 6 FIG. Although not particularly shown in the above-described embodiments, a hand or an object may enter the vicinity of the contact portion from the outside, for example, a person may pinch a hand when the contact member comes into contact with the contact portion. In order to prevent the situation described above, a configuration may be adopted in which a protection member for preventing intrusion of a hand or object from the outside is provided around the contact portion. As the protection member, a cylindrical member or the like surrounding the movable range of the contact member can be used.

As described above, according to the sixth embodiment, in addition to the effects of the above-described embodiments, a person can put a hand between the contact member and the contact portion, or the object can be placed and adjusted. A control valve lift stopper capable of avoiding a situation such as a malfunction of the valve can be obtained.

In each of the embodiments described above, the lift position can be adjusted. However, even if the contact member is fixedly attached directly to the stem shaft 3 or the like, the lift stopper can be adjusted. Needless to say, it can be made to function as. Alternatively, the abutment member may be fixed, and the height of the abutment portion may be adjustable so that the lift position can be adjusted. Further, each of the above-described configurations is merely an example, and it goes without saying that various other changes can be made.

Further, in each of the above embodiments, the contact portion with which the contact member contacts is provided on the yoke 12, but the configuration near the lower portion of the cylinder case of the control valve is shown in FIG. If it is different from the above, it goes without saying that various changes are possible, such as providing the contact portion on the bonnet 22 on the lower surface of the cylinder case or changing the shape of the yoke.

In each of the above embodiments, the case where the contact member is provided on the stem shaft 3 or the stem connector 4 of the shaft connected to the plug 1 has been described.
Needless to say, a configuration in which the valve shaft 2 is provided below the stem connector 4 and a contact portion is provided in a corresponding portion is also possible.

In each of the above embodiments, the air inlet / outlet 1
When air is introduced from the plug 1, the piston 5 rises and the plug 1
Is a reverse-acting control valve in which the pressure rises.
The air inlet / outlet 11 is provided at the upper part of the cylinder case 21 and the spring 9 is provided at the lower part. When air is introduced from the air inlet / outlet 11, the piston 5 descends and the plug 1 descends. Applicable to In addition,
In the case of the control valve of the positive operation type, the piston 5 is moved to the upper part 7 of the cylinder case without air pressure being introduced from the air inlet / outlet 11.
, The function of the lift stopper is automatically performed. For example, it is possible to apply the lift stopper of the present invention so that the lift position can be adjusted.

The control valve in each of the above embodiments is of a type that opens when the plug 1 moves to the cylinder case 21 side, but the plug 1 and the valve seat 14 in the valve box 13 fall over. There are a small number of so-called reverse plug type control valves which are arranged and close when the plug 1 moves to the cylinder case 21 side. In this case,
For example, the contact member is provided on the valve shaft 2, and the contact portion is provided on the upper surface of the valve box 13.
It is possible to configure a stopper for preventing the movement of the plug 1 to the opposite side beyond a certain limit, to prevent the plug 1 from colliding with the valve box 13 or to adjust the movable range of the plug 1.

[0053]

As described above, according to the first aspect of the present invention, the shaft connected to the plug is provided outside the cylinder case, and when the plug attempts to move to the cylinder case side by a certain limit or more. Is provided with a contact member for preventing the movement by contacting a contact portion provided on the lower surface of the cylinder case or on the plug side outside of the cylinder case, as in a conventional lift stopper. It is not necessary to precisely cut the inner surface of the cylinder case over a long period of time, and it is not necessary to construct the cylinder case with many parts. This has the effect that it is possible to provide a lift stopper on the control valve, so that the plug collides with the valve box and the plug falls off the valve shaft. Or, there is an effect that it is possible to prevent a situation such as damage to the plug and valve box, etc. occurs.

Also, since it is not necessary to increase the thickness of the upper part of the cylinder case, it is possible to avoid an increase in the center of gravity of the control valve, and it is possible to provide the lift stopper at a position close to the center of the control valve. There is an effect that the center of gravity of the valve can be made close to the center, and a light-weight, vibration-resistant control valve can be configured.

According to the second aspect of the present invention, since the contact member is provided so as to be movable in the axial direction of the shaft connected to the plug, the contact member located outside the cylinder case is moved. There is an effect that the lift position can be easily adjusted.

According to the third aspect of the present invention, since the stem connector for connecting the pressure member side portion and the plug side portion of the shaft connected to the plug is used as the contact member, special additional parts are provided. Thus, there is an effect that a lift stopper can be provided in the control valve without the need for the control valve.

According to the fourth aspect of the present invention, since the protection member for preventing the intrusion of a hand or an object from the outside is provided around the contact portion, the contact member and the contact portion are provided. There is an effect that it is possible to avoid a situation in which a person grips the hand or an object grips the control valve and malfunctions.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a control valve to which a lift stopper for a control valve according to a first embodiment of the present invention is applied.

FIGS. 2A and 2B are diagrams showing details of the structure of a lift stopper for a control valve according to Embodiment 1 of the present invention, wherein FIG. 2A is a partial cross-sectional side view near the lift stopper, and FIG. It is a perspective view of a stopper member.

FIG. 3 is a diagram showing details of the structure of a stopper member of a control valve lift stopper according to a second embodiment of the present invention;
(A) is a top view and (b) is a side sectional view.

4A and 4B are diagrams showing details of a structure of a lift stopper for a control valve according to Embodiment 3 of the present invention, wherein FIG. 4A is a partial cross-sectional side view near the lift stopper, and FIG. It is a top view, (c) is a side view which shows the shape of the stem shaft in the vicinity of a lift stopper.

5A and 5B are diagrams showing details of the structure of a lift stopper for a control valve according to a fourth embodiment of the present invention, wherein FIG. 5A is a side sectional view near the lift stopper, and FIG. FIG.

FIG. 6 is an exploded perspective view showing details of a structure of a control valve lift stopper according to a fifth embodiment of the present invention.

FIG. 7 is a partially sectional side view showing a conventional control valve having a lift stopper.

FIG. 8 is a side sectional view showing an upper part of a conventional control valve having a lift stopper according to another configuration.

[Explanation of symbols]

 2 Valve shaft (shaft connected to plug, plug side portion) 3 Stem shaft (shaft connected to plug, portion on pressure member side) 4 Stem connector 4a, 4b Connector member (contact member) 5 Piston (pressure member) 12a Lift stopper contact part (contact part) 21 Cylinder case 30a, 30b, 51 Stopper member (contact member) 41 Bolt (contact member)

Claims (4)

[Claims] 1. A control valve which is connected to a shaft connected to a plug in a valve box, and has a pressure member for transmitting a driving force to said plug by reciprocating in a cylinder case under a biasing pressure on each surface. A lift stopper for a control valve for preventing the plug from moving toward the cylinder case side beyond a certain limit, wherein the shaft connected to the plug is provided outside the cylinder case, and the plug is fixed to the cylinder case side. A contact member for preventing the movement by contacting a contact portion provided on the lower surface of the cylinder case or the plug side outside of the cylinder case when trying to move more than the limit. Control valve lift stopper. 2. The lift stopper for a control valve according to claim 1, wherein the contact member is provided so as to be movable in an axial direction of a shaft connected to the plug. 3. A lift stopper for a control valve according to claim 1, wherein a stem connector for connecting the pressure-acting member side portion and the plug side portion of the shaft connected to the plug is used as a contact member. 4. A lift stopper for a control valve according to claim 1, wherein a protection member is provided around the contact portion for preventing intrusion of a hand or an object from the outside.