JPS6143590B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve device that eliminates the cause of vibration.

For example, in a steam turbine device used in a power plant or the like, steam generated in a boiler is supplied to a turbine through a valve device, and the output, flow rate, etc. are controlled by the valve device. As the above-mentioned valve device, one consisting of a main valve and a sub-valve as shown in FIG. 1 is generally used. That is, in FIG. 1, 1 is a main valve seat, 2 is a hollow main valve body that moves forward and backward in the direction of the axis C of this main valve seat 1, 3 is a sub-valve seat formed in this main valve body 2, Reference numeral 4 denotes a sub-valve body that moves forward and backward within the main valve body 2 in the direction of the axis C. The sub-valve body 4 is integrally formed with the lower end of the valve stem 5. Therefore, the main valve body 2 is connected to the main valve seat 1.
The sub-valve body 4 is joined to the sub-valve seat 3. In the state shown in Figure 1, the flow path is blocked, but
As the valve stem 4 ascends, the sub-valve body 4 first reaches the sub-valve seat 3.
A flow path is formed between the sub-valve body 4 and the sub-valve seat 3. Therefore, the steam flows from the upstream side of the sub-valve body 4 to the downstream side through the space between the sub-valve body 4 and the sub-valve seat 3, and flows into the main valve seat 1 from the most downstream opening end in the main valve body 2. do. When the valve stem 5 is further raised, the sub-valve body 4 comes to pull up the main valve body 2 as shown in FIG. A flow path is formed between the seat 1 and the
Steam flows down through the flow path due to the pressure difference between the pressure P ₁ on the upstream side of the main valve body 2 and the pressure P ₂ on the downstream side.

By the way, in conventional valve devices of this kind, when the valve opening is small and the ratio P ₂ /P ₁ between the upstream pressure P ₁ and the downstream pressure P ₂ is relatively small, the broken line in FIG. An axially symmetrical flow pattern as shown by the arrow is formed, but as P ₂ /P ₁ increases, the flow changes to an asymmetrical flow pattern as shown by the solid line arrow in FIG. Therefore, the relationship between the valve opening degree P ₂ /P ₁ is as shown in FIG. 3, and there is an unstable region when moving from one flow type to another. Therefore, the operating curve shown in the figure always passes through the unstable region, and when passing through this unstable region, a force due to large pressure fluctuations acts on the main valve body 2. This fluctuating force vibrates the valve bodies 2 and 4, causing noise generation and also becoming a cause of damage to the entire valve device. Therefore, in the past, in order to prevent damage to various parts of the valve device, it was necessary to use expensive materials that would not be damaged, and even if such materials were used, noise could not be prevented.

The present invention was made in view of the above circumstances, and its purpose is to eliminate vibration in a region where the valve opening is relatively small with a simple configuration, and prevent damage to various parts without using expensive materials. The object of the present invention is to provide a valve device that can perform the following steps.

The details of the present invention will be explained below based on the embodiment shown in FIG. In Fig. 4, 11 is the main valve seat;
12 is a hollow main valve body that moves forward and backward in the direction of the axis C of the main valve seat 11; 13 is a sub-valve seat formed within the main valve body 12; This is a sub-valve body that moves forward and backward in the direction of the core C. The sub-valve body 14 is integrally formed with the lower end of the valve stem 15.

Therefore, the radius of curvature on the longitudinal section of each joint 14a, 13a of the sub-valve body 14 and the sub-valve seat 13
The relationship between R ₁ and R ₂ is R ₁ <R ₂ . Further, a flow path 12a in the main valve body 12 from the sub-valve seat 13 to the most downstream opening end gradually becomes larger in diameter from the sub-valve seat 13 toward the downstream side. Furthermore, the cross-sectional shape of the most downstream opening end 12b in the main valve body 12 is not rounded, but is formed into a sharp edge shape.

With such a configuration, the main valve body 2 is connected to the main valve seat 1.
By moving the valve rod 15 upward while the valve rod 15 is connected to the sub-valve body 14, the sub-valve body 14 is separated from the sub-valve seat 13, and a flow path is formed between the sub-valve body 14 and the sub-valve seat 13. At this time, the steam flow passing between the sub-valve body 14 and the sub-valve seat 13 flows down not along the sub-valve body 14 but along the sub-valve seat 13 having a large radius of curvature. This is a phenomenon known as the wonder effect. Also, main valve body 1
Since the flow path 12a in the main valve seat 11 gradually becomes larger in diameter toward the downstream, the steam flow that has flowed down along this flow path 12a leaves the opening end 12b and diffuses outward, and flows inside the main valve seat 11. It will follow the circumference. Note that since the cross-sectional shape of the open end 12b is formed into a sharp edge shape, the steam flow can smoothly leave the open end 12b. And further valve stem 1
5, the main valve body 12 is pulled up by the sub valve body 14, and the steam on the upstream side of the main valve body 12 passes through the flow path formed between the main valve body 12 and the main valve seat 11. flows downstream. At this time, the main valve seat 11
The steam flow flowing down along the flow path 1 in the main valve body 12
Since it is pushed from the inside by the steam flow that has flown down through 2a, both steam flows meet on the inner peripheral surface of the main valve seat 11 and flow down along this inner peripheral surface.

Therefore, according to the valve device shown in FIG. 4, the steam flow that has passed through the main valve seat 11 is forced to become an axially symmetrical flow due to the small amount of steam flow from the auxiliary valve, unlike the conventional device. The flow type does not change. Therefore, even in a region where the valve opening degree is relatively small, there is no unstable region as shown in FIG. Damage can be prevented and noise can be prevented.

In addition, each joint part 1 of the sub-valve body 14 and the sub-valve seat 13
The relationship between the curvature half molds R ₁ and R ₂ on the longitudinal section in 4a and 13a should be R ₁ < R ₂ , but especially R ₁ <
The effect can be enhanced by setting R ₂ /2.

As described in detail above, according to the present invention, the valve opening degree is relatively small due to the extremely simple configuration of the sub-valve body, the sub-valve seat, and the shape of the downstream side of the sub-valve seat in the main valve body. It is possible to provide an inexpensive valve device that can eliminate vibration in a small area and prevent noise and damage to various parts.

[Brief explanation of the drawing]

1 and 2 are vertical sectional views showing a conventional example, FIG. 3 is a view showing a flow type, and FIG. 4 is a vertical sectional view showing an embodiment of the present invention. 1, 11... Main valve seat, 2, 12... Main valve body,
3, 13... Sub-valve seat, 4, 14... Sub-valve body.

Claims (1)

[Claims] 1. A main valve seat, a hollow main valve body that moves forward and backward in the axial direction of the main valve seat, a sub-valve seat formed within the main valve body, and a main valve seat formed within the main valve body. It is equipped with a sub-valve body that moves forward and backward in the axial direction of the main valve seat, and the relationship between the radii of curvature R ₁ and R ₂ on the longitudinal section at each junction of the sub-valve body and the sub-valve seat is expressed as R ₁ < A valve device characterized in that the diameter of the flow path in the _main valve body is gradually increased from the sub-valve seat toward the downstream side. 2. The valve device according to claim 1, wherein a cross-sectional shape of the most downstream opening end in the main valve body is formed into an edge shape.