JPH026387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a throttle valve of a type in which pressure is reduced through multi-stage circular holes or elongated holes provided in a valve seat, a valve body, or the like.

BACKGROUND TECHNOLOGY This valve consists of a conventionally known valve body, a hollow cylindrical valve seat attached to the valve body, and a valve body that can freely reciprocate within the valve. This type of throttle valve, which reduces the pressure of high-pressure fluid through a hole or a long hole, has a valve body and valve seat seal immediately after the throttle. Because the parts are in the same place,
The sealing parts of the valve body and valve seat are designed to protect against high-speed jets generated by high-pressure fluid at the rear of the throttle part and fluids such as condensate contained in steam and oxidized scale when the valve is opened. Often eroded by spraying.

Already, as a measure to prevent this erosion, Stellite is applied to the seals of the valve body and valve seat. Even if the valve members are made of gold or the like, these valve members may undergo erosion.
There is a strong desire from various quarters for the emergence of a throttle valve that has strong resistance to erosion.

The structure of a conventionally known throttle valve of this type will now be described with reference to FIGS. 1 and 2 of the accompanying drawings showing one example thereof.

As shown in the figure, a hollow cylindrical valve seat 2 is attached to a valve body 1.
is attached, and a gasket 3 seals between the valve box 1 and the valve seat 2. Further, a valve stem 5 is screwed into a valve body 4 which is movably disposed within the valve seat 2 so as to cooperate with the valve seat 2, and after the valve stem 5 is screwed into the valve body 4, , is fixed to the valve body 4 by a set pin 6, and the outer surface of the set pin 6 is welded to prevent it from coming off.

The valve body 4 is made to be able to move up and down as shown by arrow The passage area of the multi-stage circular holes and long holes provided in the wall in the direction of the longitudinal axis of the valve stem 5 is narrowed around the bottom of the valve body 4 to sequentially change the pressure of the fluid. Try adjusting the flow rate.
In the figure, 7 and 8 indicate the sealing surfaces of the valve body 4 and the valve seat 2, respectively, and 9 indicates the circular holes or elongated holes provided in multiple stages in the hollow cylindrical wall of the valve seat 2. .

In particular, FIG. 2 shows an enlarged view of the main part of the valve seat 2 in the intermediate throttle state of the throttle valve shown in FIG.
A portion of the passage area is blocked by the sealing surface 7 of the valve body 4, and the portion A shown in the figure becomes the minimum passage area. Therefore, the fluid flow indicated by arrow f becomes a considerably high-speed flow at the outlet of the circular hole or elongated hole 9, advances in the direction of arrow B, and after colliding with the sealing surface 7 of the valve body 4. , passes through the minimum passage area A between the valve seat 2 and the maximum flow velocity between the sealing surface 7 immediately after that and the correspondingly tapered sealing surface 8 of the valve seat 2. C
It changes direction at , and flows into the throat section 10 .

In this case, fluid always collides with the sealing surface 7 of the valve body 4 while the valve body 4 is moving up and down, and at this time, high-speed jets, condensate contained in steam, and oxide scale The seal surfaces 7 and 8 often undergo erosion due to spraying such as, and in this state, the maximum flow velocity portion C
If the valve is closed, valve seat leakage will occur, and erosion of the valve body 4 and valve seat seal portions 7 and 8 will progress rapidly.

In order to prevent this erosion as much as possible, it is common practice to apply stellite overlays to the seal parts 7 and 8 as shown in the figure, but this effect is not necessarily perfect. is the current situation.

Problems to be Solved by the Invention An object of the present invention is to obtain a throttle valve that can effectively prevent the occurrence of erosion in the seal portion of the valve body and valve seat in conventionally known throttle valves. It is something.

Means for Solving the Problems In order to achieve this object, the present invention forms the sealing surface of the valve body on the back side of the fluid flow, and protects the sealing surface of the valve body on the front side of the fluid flow. A wall is provided, and the sealing surface of the valve seat is provided in a groove shape below the straight forward position of the fluid flow.
The present invention is characterized in that direct collision of fluid jets with the sealing surfaces of the valve body and valve seat can be prevented, and the generation of erosion on the sealing surfaces can be effectively prevented.

Embodiments Hereinafter, the present invention will be described in the attached drawing No. 3 showing the embodiments thereof.
This will be explained in detail based on FIGS.

First, as shown in FIGS. 3 and 4, a valve body sealing surface protection wall 11 is installed at the lower end of the hollow cylindrical valve body 4 on the front side of the fluid flow f so as to be able to withstand the collision of fluid. A tapered valve body sealing surface 17 is formed on the back side of the fluid flow f, and the tapered valve body sealing surface 17 is inclined upward toward the axis of the valve body 4. A sealing surface 18 of the valve seat 2 is formed below the straight-advancing position of the flow f in a tapered shape that slopes downward toward the outer diameter side.

Further, when the valve is closed, a gap is provided between the lower peripheral end of the valve body 4 and the bottom of the groove of the sealing surface 18 of the valve seat 2, so that both sealing surfaces 17 at the maximum flow velocity portion C, 18 will be seated securely. The other structure is the same as the conventional type shown in FIGS. 1 and 2, and as the valve stem 5 moves up and down in the direction of the arrow X, the valve body 4 also moves up and down, and the valve seat 2 They are substantially the same in that they sequentially change the passage area of the provided multistage circular holes and the elongated hole 9 to throttle and adjust the pressure and flow rate.

FIG. 4 shows an enlarged view of the main part of the valve seat 2 when the throttle valve shown in FIG. 3 is in the intermediate throttle state. The sealing surface 17 of the valve body 4 formed at the lower end of the valve body 4 is in a state of being closed by the protective wall 11, and a high-speed jet is generated at the minimum passage area portion A. The sealing surface 17 of the body 4 is
Since the sealing surface 18 of the valve seat 2 is located on the back side of this jet and is provided below the position where this high-speed jet flows straight, the high-speed jet that travels in the direction of arrow B is Sealing surfaces 17 and 18 of seat 2
It is guided through the throat 10 to the outlet side of the valve without colliding with the valve. In this way, erosion of the sealing surfaces 17, 18 due to high-speed jets is prevented.

Next, FIGS. 5 and 6 show another embodiment of the present invention, in which a cylindrical portion 20 is formed integrally with the lower end of the valve body 4, and this cylindrical portion 2
A circular hole 21 is bored in multiple stages in the wall of the valve body 4, and when the valve stem 5 moves up and down in the direction indicated by the arrow The passage area of the circular hole 21 provided in the section 20 is sequentially changed to throttle and adjust the pressure and flow rate.

Note that relatively large holes 22 are drilled in the valve seat 2, but these holes 22 are for rectifying the fluid, and the multi-stage circular holes 2 of the valve body 4
Compared to No. 1, the passage area is much larger and there is almost no aperture effect.

In this embodiment as well, the structure of the seal surfaces 17 and 18 formed on the valve body 4 and the valve seat 2 is the same as that of the embodiment shown in FIGS. 3 and 4, and has exactly the same function and effect. This is what we are doing. In addition, in FIGS. 5 and 6, reference numerals 23 and 24 indicate a flow path portion within the cylindrical portion 20 of the valve body 4 and a guide portion of the valve body 4, respectively.

Furthermore, FIG. 6 shows an enlarged view of the main part of the valve seat 2 when the throttle valve shown in FIG. The entrance of the uppermost one of the multistage circular holes 21 provided in the valve seat 20 is partially closed by the upper peripheral surface of the guide portion 24 of the valve body 4 formed in the valve seat 2. , Point A shown in the same figure is the minimum passage area, and a high-speed jet forms immediately after this minimum passage area A or at the outlet of the multi-stage circular hole 21, but this high-speed jet does not reach the valve body 4 or the valve seat. The sealing surface 17 of the valve body 4 is formed downstream of the sealing surface 17 or 18 of the valve seat 2, and the sealing surface 17 of the valve body 4 is on the back side of the fluid flow f from the direction of the arrow B, and the sealing surface 18 of the valve seat 2 is located downstream of the fluid flow f from the direction of the arrow B. The high-speed jets do not collide directly with the sealing surfaces 17 and 18 of the valve body 4 and the valve seat 2, but rather directly impact the valve body 4. It is led to the valve outlet side through the flow path portion 23 in the cylindrical portion 20 at the lower end.

In this way, even in the case of this example,
The sealing surfaces 17 and 18 of the valve body 4 and the valve seat 2 are not eroded by high-speed jets or the like. In addition, in both embodiments, the sealing surfaces 7, 8
It goes without saying that the corrosion resistance of 17 and 18 can be further increased by applying a stellite overlay or the like.

Effects of the Invention As can be seen from the above description, according to the present invention, even during the vertical movement of the valve stem, the high-speed jet does not directly collide with the sealing surface of the valve body and valve seat. Therefore, it is an object of the present invention to provide a throttle valve that can effectively prevent the occurrence of erosion of the sealing surfaces of the valve body and valve seat due to high-speed jets and the spraying of condensate and oxide scale contained in steam. .

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional throttle valve;
Figure 2 is an enlarged view of the main parts of the valve seat, and Figure 3 is:
4 is an enlarged view of the main parts of the valve seat, FIG. 5 is a sectional view showing another embodiment of the invention, and FIG. 6 is a sectional view of the valve seat. It is an enlarged view of the main part of the seat. 1... Valve box, 2... Valve seat, 4... Valve body, 5...
Valve stem, 7... Gasket, 9, 21... Multi-stage circular hole or elongated hole portion, 10... Throat, 11... Valve body sealing surface protection wall, 17... Valve body sealing surface, 18...
... Valve seat sealing surface, 20 ... Cylindrical part, 22 ... Hole,
23...Cylindrical channel portion at the tip of the valve body, 24...Valve body guide portion.

Claims (1)

[Claims] 1 Consists of a valve body, a substantially hollow cylindrical valve seat attached to the valve body, and a valve body that can freely reciprocate within the valve seat, and includes a large number of valve bodies formed on the valve seat or the valve body. In a throttle valve that is designed to reduce pressure through a circular hole, a long hole, etc., there is a valve on the front side of the fluid flow facing the circular hole, long hole, etc. formed in the valve seat or valve body. In addition, the valve body is provided with a tapered seal surface that slopes toward the lower end of the valve body on the back surface against the fluid flow, and the valve seat is provided with a tapered seal surface that is inclined toward the lower end of the valve body against the fluid flow. It is characterized by providing a tapered sealing surface that slopes downward to the outer diameter side from the straight forward position of the flow to prevent the fluid jet from directly colliding with the valve body and the valve seat sealing surface. Throttle valve. 2. The throttle valve according to claim 1, wherein each sealing surface is provided with a stellite filler. 3. The throttle valve according to claim 1 or 2, wherein multistage circular holes, long holes, etc. are formed in the wall of the hollow cylindrical portion of the valve seat. 4. The throttle valve according to claim 1 or 2, wherein multistage circular holes, elongated holes, etc. are formed in the wall of the hollow cylindrical portion that hangs down from the lower end of the valve body.