JPH0648069B2 - Valve device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve device having a contoured valve plug, and more particularly to a valve device suitable for controlling a high pressure fluid.

[Prior Art] Generally, in a valve device that controls a high-pressure fluid, it is necessary to attach importance to not only the characteristics at the control opening but also the valve closing function. If the valve closing function is incomplete and there is a very slight leakage flow of fluid in the fully closed state,
Due to the high differential pressure, a kind of cavitation erosion called wire drawing phenomenon occurs in this leak flow and locally erodes the seat ring and the seat surface of the valve plug, further increasing the amount of fluid leakage when fully closed, This is because the valve closing function will eventually be lost and the valve will become unusable within a short period of time. Therefore, conventionally, as one method for solving such a problem, as shown in FIG. 3, two seat portions 3, 4, 5, 6 are provided in the seat ring 1 and the valve plug 2 so as to be separated from each other in the axial direction. It is known that each is provided to improve the valve closing performance.

[Problems to be Solved by the Invention] However, in such a method using two seat portions, when the leak performances of both seat portions are made to be about the same, the differential pressure condition applied to each seat surface is Divided into
Although the best performance is achieved, in order to actually realize this condition, the space between the two seat portions 3 and 4 formed on the seat ring 1 and the space formed on the valve plug 2 are 2.
It is necessary to make the intervals between the two sheet portions 5 and 6 exactly equal, which requires high processing accuracy, and there is a drawback that a confirmation test of leak characteristics of each sheet portion after processing is required.

Further, if a significant difference is found in the leak characteristics of each seat surface in the confirmation test, it is necessary to perform additional work to readjust the seat portion.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to improve the valve closing function with a relatively simple structure and to generate cavitation called a wire loading phenomenon. It is to provide a valve device capable of preventing the above.

[Means for Solving the Problems] The present invention has been made to achieve the above-mentioned object, and is a cylindrical seat ring having a fluid passage hole, and the fluid which is slidably disposed in the seat ring. In a valve device having a valve plug for controlling the opening and closing of a passage hole, the seat ring and the valve plug are respectively provided with a primary side seat part and a secondary side seat part which are axially separated from each other and seated against each other when fully closed. The side seat portion is configured to be movable in the axial direction, and a communication hole for communicating a space formed between the seat ring, the valve plug, and the primary and secondary seat portions with a downstream side of the secondary seat portion is provided. The pressure control valve is formed in the valve plug and the communication hole is incorporated.

[Operation] In the present invention, the movable seat portion provided on the seat ring or the valve plug is moved by contact with the mating seat portion when the valve is closed, and absorbs a processing error. The pressure control valve incorporated in the valve plug is operated by the fluid pressure in the space formed between the seat ring, the valve plug and the primary and secondary seats when the valve is closed, and maintains a constant pressure. When the pressure control valve is opened, a part of the fluid in the space flows out to the downstream side through the communication hole formed in the valve plug.

[Examples] The present invention will be described in detail below based on the examples shown in the drawings.

FIG. 1 is a cross-sectional view of a main part of a valve device according to an embodiment of the present invention when a valve is closed, and FIG. 2 is a cross-sectional view of a main part in a minute opening state. In these figures, 10 is a basket-type valve body whose inside is partitioned by a partition wall 11 into an upstream side (primary side) flow path 12A and a downstream side (secondary side) flow path 12B, and 13 is the center of the partition wall 11. A tubular seat ring screwed into the formed screw hole 14 via a gasket 15. The central hole of the seat ring 13 forms a fluid passage hole 16, and the fluid passage hole 16 has upper and lower open ends. Has primary side and secondary side sheet portions 17 and 18, respectively.

In this case, the primary seat portion 17 is formed on the inner peripheral surface of the lower end side of the fluid passage hole 16 to form a fixed seat portion. On the other hand, the secondary side seat portion 18 is an inner peripheral surface of an upper end side opening portion of a tubular floating seat ring 20 which is vertically movably fitted to an inner peripheral surface of an upper end side of the fluid passage hole 16 via a sheet member 21. The movable seat portion is formed by being formed.

A guide 22 is disposed above the seat ring 13 and coaxial therewith, and slidably guides and holds a valve plug 30, which will be described later. The guide 22 is formed in a cylindrical body.
A collar portion 22A is integrally formed on the outer peripheral surface of the upper end portion.
A is an opening 2 formed in the center of the upper surface of the valve body 10.
3 through the gasket 24, and the guide 22
The lower ends of the above are fitted to the outer peripheral surfaces of the upper ends of the seat ring 13 and the floating seat ring 20. A flow hole 26 is formed in the guide 22 so as to pass through the guide hole 22 in the radial direction to connect the center hole 28 to the secondary side flow passage 12B of the valve body 10, and an annular groove 29 is formed on the inner peripheral surface of the flow hole 26. Is formed corresponding to.

Reference numeral 27 denotes an upper lid that is fitted into the upper surface opening 23 of the valve body 10 and is fixed by bolts and nuts (not shown). The upper lid 27 presses the guide 22 to fix it to the seat ring 13.

The valve plug 30 is a contoured valve plug 15
And the lower end is the central hole 2 of the guide 22.
8. The floating seat ring 20 and the seat ring 13 are slidably fitted and are configured to control the opening and closing of the fluid passage hole 16 by moving up and down by the valve shaft 31. Primary and secondary seat portions 32 and 33 are formed on the outer peripheral surface of the lower end portion and the outer peripheral surface of the intermediate portion of the valve plug 30, corresponding to the primary side and secondary seat portions 17 and 18 of the seat ring 13. There is. These seat portions 32 and 33 are fixed seat portions formed by being directly formed on the valve plug 30, and are seated on the primary side and secondary side seat portions 17 and 18 of the seat ring 13 when the valve is closed. Below the primary side seat portion 32, a first characteristic portion 35 having a substantially conical shape is formed.
The lower portion of the secondary side seat portion 33 in the middle portion of the valve plug 30 is a tapered second characteristic portion 36 having a smaller diameter on the lower end side. Also valve plug 30
A communication hole 37 in which a pressure control valve 38 is incorporated inside
Are formed. The communication hole 37 defines a closed space 40 formed between the seat ring 13 and the valve plug 30 and the primary side and secondary side seat portions 17, 18, 32, 33 when the valve is closed, and the inner peripheral surface of the guide 22. And valve plug 30
To communicate with the downstream side flow passage 12B of the valve body 10 through the gap G between the outer peripheral surface of the upper end portion and the flow hole 26,
One end opening 37a is the peripheral surface of the lower end portion of the valve plug 30,
The opening is formed in a portion between the primary side sheet portion 32 and the second characteristic portion 36, and the other end opening portion 37b is opened in the outer peripheral surface of the upper end portion.

The pressure control valve 3 incorporated in the communication hole 37.
Reference numeral 8 is a multi-stage pressure adjusting valve which keeps the fluid pressure P ₂ in the seat ring 13, that is, the space 40, at a constant pressure, and is normally urged downward by the spring force of the spring 41 so that the communication hole is normally formed. 37 is cut off, and when the fluid pressure in the seat ring 13 becomes equal to or higher than a certain pressure P ₂ , it operates to open the communication hole 37.

The floating seat ring 20 is movable in the vertical direction by Δd by the step portions 45 and 46 formed on the inner peripheral surfaces of the seat ring 13 and the guide 22. Δd is set in consideration of the dimensional error between the sheet portions 17 and 18 and 32 and 33, and is set to about 1 mm.

In the valve device having such a configuration, FIG. 1 shows a fully closed state immediately after the valve plug 30 is lowered to close the valve. In this state, the primary side and secondary side seat portions 32 and 33 of the valve plug 30 are respectively seated on the primary side and the secondary seat portions 17 and 18 of the seat ring 13, and the internal space 40 of the seat ring 13 becomes a closed space. To be done. Also,
When the valve plug 30 descends, the secondary seat portion 33 is seated on the secondary seat portion 18 of the floating seat ring 20 immediately before the end of the descending, and when the valve plug 30 descends, the floating seat ring 20 also slides on the valve plug. The primary sheet portion 32 is lowered integrally with 30, and the primary side sheet portion 32 is seated on the primary side sheet portion 17 by adhesion. Therefore, the seat portion 17 of the seat portions 32 and 33,
The seating against 18 is accurate and reliable, and the floating seat ring 20 descends to absorb the processing error of these seats,
Makes seat processing and adjustment easier. Further, if the seat portion is properly seated, the valve closing function is improved, so that it is possible to remarkably prevent the amount of fluid leakage when the valve is closed.

When used for controlling the high-pressure fluid, for example, the fluid pressure P ₁ is 160 kg f / cm ² G and the pressure control valve 38 is 1/2 P ₁
It shall operate at (80 kg f / cm ² G). The valve plug 30 is raised to raise the primary side and secondary side seat portions 32, 33.
In the opening state (fluid control state) in which is separated from the primary side and secondary side seat portions 17 and 18, the high-pressure fluid of pressure P ₁ that has flowed into the upstream side flow passage 12A of the valve body 10 is discharged from the seat ring 13. It flows into the fluid passage hole 16 through the lower end opening, passes through the annular groove 29 of the guide 22 and the circulation hole 26, and flows out to the downstream side flow passage 12B. At this time, when the fluid having the pressure P ₁ flows into the fluid passage hole 16 of the seat ring 13, the pressure of the fluid changes from P ₁ to P ₂ (160 kg f / cm ² G → 80 kg f /
The pressure is reduced to cm ² G), and this reduced pressure fluid is further reduced (P ₃ = 0 kg f / cm ² G) by flowing between the secondary side sheet portions 18 and 33 and flowing into the downstream side flow path 12B. It

In other words, the present invention reduces the pressure by two stages at the control opening degree by the two seat portions.

Next, the valve plug 30 is gradually lowered from this state, and when the secondary side seat portion 33 is seated on the secondary side seat portion 18, the fluid passage hole 16 of the seat ring 13 and the downstream side flow passage 12B. The fluid pressure P ₂ inside the seat ring 13 is temporarily P ₁ (= 160 kg f
/ cm ² G) to the same pressure. Immediately after this, when the primary side seat portion 32 is seated on the primary side seat portion 17 and is in the valve closed state, the pressure control valve 38 operates by the pressure P ₂ in the seat ring 13 and the communication hole 3 as described above.
Open seven. Therefore, a part of the fluid in the seat ring 13 flows out to the downstream side flow passage 12B through the communication hole 27, the gap G between the guide 22 and the valve plug 30, the annular groove 29 and the flow hole 26, and the seat ring 13 The internal pressure P ₂ to 8
Lower to 0 kg f / cm ² G. And P ₂ = 80 kg f /
When the pressure reaches cm ² G, the spring 41 of the pressure control valve 38 and the pressure P ₂ are balanced, so that the control valve 38 returns to close the communication hole 27, and thereafter, this state, that is, P ₁
= 160kg f / cm ² G, P ₂ = 80kg f / cm ² G, P ₃ = 0kg
Holds f / cm ² G. As a result, the seat portions 17, 32
And the differential pressure (= 80 kg f / c
m ² G) can be loaded, and by providing the floating seat ring 20 as described above, the valve closing function of the seat can be improved, so that the amount of fluid leakage by both seal parts is about the same. Moreover, since the amount can be made extremely small, erosion of the seat surface due to cavitation is reduced, and the seat leak performance can be stably maintained for a long period of time.

Although the secondary side seat portion 18 provided on the seat ring 13 is the movable seat portion in the above-described embodiment, the present invention is not limited to this, and any one of the four movable seat portions is used. As long as it is configured.

[Effects of the Invention] As described above, in the valve device according to the present invention, the seat ring and the valve plug are provided with the respective seat portions, and any one of the seat portions can be moved in the axial direction of the valve plug. Since it is configured, the processing error of the seat portion can be absorbed, the seat portions can be reliably seated, and the valve closing function is improved. Therefore,
The seat portion can be easily processed and adjusted, and cavitation due to fluid leakage when the valve is closed can be prevented and prevented, improving the reliability and durability of the valve device.

Further, according to the present invention, a communication hole in which a pressure control valve is incorporated is formed in the valve plug, the communication space communicates the internal space of the seat ring with the downstream flow passage, and the pressure control valve equalizes the differential pressure. The differential pressure applied to the first and second seat portions can be made substantially equal, and the leak performance can be made substantially the same.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a valve device according to the present invention immediately after the valve is closed, FIG. 2 is a sectional view of a main part in a minute opening state, and FIG. 3 is a seat of a conventional valve device. It is sectional drawing of a ring and a valve plug. 10 ... Valve main body, 11 ... Partition wall, 12A ... Upstream flow passage, 12B ... Downstream flow passage, 13 ... Seat ring, 1
6 ... Fluid passage hole, 17 ... Primary side seat part, 18 ...
Secondary side seat part, 20 ... Floating seat ring, 22 ...
Guide, 26 ... Circulation hole, 30 ... Valve plug, 32
...... Primary side seat part, 33 ...... Secondary side seat part, 37 ...
... Communication hole, 38 ... Pressure control valve, 40 ... Space.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-49-35918 (JP, A) JP-A-35-8594 (JP, Y1) JP-A-55-26610 (JP, Y2)

Claims (1)

[Claims] 1. A valve device comprising a cylindrical seat ring having a fluid passage hole, and a valve plug slidably disposed in the seat ring for controlling the opening and closing of the fluid passage hole. The valve plug is provided with a primary side seat part and a secondary side seat part that are axially separated from each other and seated against each other when fully closed, and the secondary side seat part is configured to be movable in the axial direction. And a communication hole for communicating the space formed between the primary and secondary seat portions and the downstream side of the secondary seat portion is formed in the valve plug, and a pressure control valve is incorporated in the communication hole. Valve device characterized by.