JPH10159995A - Valve gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve gear capable of holding unbalanced force acting on its plugs substantially constant irrespective of the lifts thereof. SOLUTION: The fluid flowing through an inflow port 9 into a valve casing 3 is divided there into an upper and a lower flow. The upper flow directed through an upper port 11 is reflected by a projection 17 and is then easily led to an upper passage 11a, while the lower flow directed through a lower port 12 is reflected by a recess 18 and is then barely led to a lower passage 12a. The control of the reflection factors by the projection 17 and the recess 18 sets the flow ratio of the upper and the lower flows at a proper value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device having a double-seat valve structure which divides a flow vertically by providing two sets of plugs and seat rings.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional valve device. In the figure, reference numeral 1 denotes an upper cover of a valve device, 2 denotes a lower cover, and 3 denotes a valve provided between an upper cover 1 and a lower cover 2. It is a box. 5 is an upper plug and 6 is a lower plug. The upper plug 5 and the lower plug 6 are coaxially attached to the valve shaft 4, and shift up and down in conjunction with the valve shaft 4. Reference numeral 7 denotes an upper seat ring paired with the upper plug 5, and reference numeral 8 denotes a lower seat ring paired with the lower plug 6. 9 is an inlet of the valve box 3 and 10 is an outlet of the valve box 3. Reference numeral 11 denotes an upper port portion formed by the upper seat ring 7, and reference numeral 12 denotes a lower port portion formed by the lower seat ring 8. 11a is an upper channel through which the fluid flowing out of the upper port portion 11 flows, and 12a is a lower channel through which the fluid flowing out of the lower port portion 12 flows.

Next, the operation will be described. The fluid flows into the valve box 3 from the inlet 9 and flows out from the outlet 10. When the lift amount is 0%, that is, when the upper plug 5 and the upper seat ring 7 are in close contact with each other, and the lower plug 6 and the lower seat ring 8 are in close contact with each other, there is almost no inflow and outflow of fluid. When the upper plug 5 and the lower plug 6 are shifted by the valve shaft 4, the fluid flowing from the inflow port 9 becomes
It flows through the upper port 11 and the upper channel 11a, and flows through the lower port 12 to the lower channel 12a. The fluid that has passed through both the upper flow path 11a and the lower flow path 12a flows out of the outlet 10.

[0004]

Since the conventional valve device is configured as described above, there are the following problems.
The conventional double-seat valve is provided with two sets of plugs and seat rings to divide the flow of fluid into upper and lower parts, and is characterized by almost canceling the unbalance force due to the upward and downward flows. However, as can be seen from FIG. 4 showing an example of the relationship between the actual lift amount and the unbalance force, the unbalance force is such that the lift amount is 0 to 50.
% Works in the plus direction (direction to open the valve), but when the lift exceeds 50%, it suddenly turns to the minus direction (direction to close the valve) and increases to 100% Keep doing. In FIG. 4, the unbalance force changes from the plus direction to the minus direction at the point where the lift amount is 50%. However, considering other cases, the unbalance force changes from the plus direction to the minus direction. Means the lift amount is 30
This is the case when it is within the range of ５０50%.

While the unbalance force is acting in the positive direction, the actuator (not shown) presses the upper plug 5 and the lower plug 6 via the valve shaft 4 to control the valve to close. . In this state, when the unbalance force turns in the negative direction,
Since the upper plug 5 and the lower plug 6 act to close the valve, the actuator controls the opening direction of the valve in order to maintain the opening of the valve. In addition, the steeper the negative force is changed in the negative direction, the steeper the control of the operating device. As described above, the conventional valve device has a problem that the control of the operating device becomes unstable when the lift amount exceeds a specific range.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a valve device capable of making an unbalance force acting on a plug substantially constant regardless of a lift amount.

[0007]

According to a first aspect of the present invention, there is provided a valve device, wherein an upper plug and an upper seat ring for adjusting a flow rate of a fluid to an upper passage are coaxial with the upper plug and the upper seat ring. In the valve device of a double-seat valve structure provided with a lower plug and a lower seat ring for adjusting the flow rate of the fluid to the lower flow path, means for facilitating the flow of the fluid to the upper flow path is formed. And / or means for preventing fluid from flowing through the lower flow path.

According to a second aspect of the present invention, the ratio between the flow rate of the upper flow path and the flow rate of the lower flow path, defined by the means for facilitating the flow of the fluid and / or the means for facilitating the flow of the fluid, is defined. 1.0: 0.7 to 0.9.

According to a third aspect of the present invention, the means for facilitating the flow of the fluid comprises a convex portion formed at the lower end of the upper lid.

[0010] In the valve device according to the fourth aspect of the present invention, the means for preventing the fluid from flowing is constituted by a concave portion formed at the upper end of the lower lid.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a sectional view of a valve device according to Embodiment 1 of the present invention.
Numeral 2 denotes a lower lid, and numeral 3 denotes a valve box provided between the upper lid 1 and the lower lid 2. 5 is an upper plug and 6 is a lower plug. The upper plug 5 and the lower plug 6 are coaxially attached to the valve shaft 4, and shift up and down in conjunction with the valve shaft 4. Reference numeral 7 denotes an upper seat ring paired with the upper plug 5, and reference numeral 8 denotes a lower seat ring paired with the lower plug 6. 9 is an inlet of the valve box 3 and 10 is an outlet of the valve box 3. 11 is an upper port portion formed by the upper seat ring 7, 1
Reference numeral 2 denotes a lower port portion formed by the lower seat ring 8. 1
1a is an upper channel through which the fluid flowing out of the upper port portion 11 flows, and 12a is a lower channel through which the fluid flowing out of the lower port portion 12 flows.

Reference numeral 17 denotes a convex portion formed at the lower end of the upper lid 1, which acts to facilitate the flow of the fluid flowing through the upper channel 11a. In order to make this effect effective, the protrusion 17
May be formed only on the opposite side of the lower end of the upper lid 1 from the upper channel 11a. Reference numeral 18 denotes a concave portion formed at the upper end of the lower lid 2, which acts to make the fluid flowing through the lower channel 12a difficult to flow. For this reason, it is effective to form the concave portion 18 around the entire upper end of the lower lid 2.

The convex portion 17 and the concave portion 18 are formed to make the unbalance force acting on the plug almost constant regardless of the lift position, as described in detail below. Therefore, if this object can be achieved, both the convex portion 17 and the concave portion 18 may be formed, or only one of them may be formed.

Next, the operation will be described. The fluid flows into the valve box 3 from the inlet 9 and flows out from the outlet 10. When the lift amount is 0%, that is, when the upper plug 5 and the upper seat ring 7 are in close contact with each other, and the lower plug 6 and the lower seat ring 8 are in close contact with each other, there is almost no inflow and outflow of fluid. When the upper plug 5 and the lower plug 6 are shifted upward by the valve shaft 4, the fluid flowing in from the inlet 9 is
It flows through the upper port portion 11 to the upper channel 11a, and flows through the lower port portion 12 to the lower channel 12a. The fluid that has passed through both the upper flow path 11a and the lower flow path 12a flows out of the outlet 10 to the outside.

FIG. 2 is a diagram showing the relationship between the lift amount of the valve device and the unbalance force according to the first embodiment of the present invention. In the figure, when the flow rate of the upper flow path 11a is 1.0, the case where the flow rate ratio of the lower flow path 12a is 0.7 is indicated by a circle, and the flow rate ratio of the lower flow path 12a is 0.9. The case is indicated by a mark.
From 0% to 60% of the lift amount, the unbalance force stably changes with a small value in the plus direction. Lift amount is 7
At 0%, in both cases, the unbalance force slightly increases in the positive direction. When the lift amount becomes 80%, when the flow rate ratio of the lower flow path 12a is 0.7 (marked with ○), the unbalance force approaches zero level, and the flow rate ratio of the lower flow path 12a becomes 0.9. In the case of (□
(), The unbalance force has a large value in the positive direction.

Although not shown in FIG. 2, the lower flow path 12a
When the flow rate ratio is 0.7 or less, the unbalance force changes from the plus direction to the minus direction at a lift of 80%. Also,
When the flow rate ratio of the lower flow path 12a is 0.9 or more, if the lift amount exceeds 80%, the unbalance force remains large in the positive direction. Therefore, when the flow rate of the upper flow path 11a is set to 1.0, the flow rate ratio of the lower flow path 12a is set to 0.1.
When set in the range of 7 to 0.9, the lift amount is 0% to 100%.
Over the entire range of%, the unbalance force maintains a small value in the positive direction.

An operating device (not shown) operates the valve shaft 4 in a direction opposite to the direction of the unbalance force in order to maintain the opening of the valve at a predetermined value.
, The operation of the operating device becomes unstable when the direction of the unbalance force changes from plus to minus or from minus to plus. That is, the lift amount is 0% to 1
If the unbalance force continues to maintain a small value in either the plus direction or the minus direction over the entire range of 00%, the control of the actuator will stably transition. As described above, the condition that satisfies this condition is that the ratio of the flow rate of the upper flow path 11a to the flow rate of the lower flow path 12a is set to 1.0: 0.7 to
0.9.

In the valve device according to the first embodiment, the flow rate of the upper flow path 11a: the flow rate of the lower flow path 12a = 1.0:
In order to satisfy 0.7 to 0.9, the convex portion 17 and / or
Alternatively, a concave portion 18 is formed. The fluid that has flowed into the valve box 3 from the inflow port 9 is divided into upper and lower portions, and one of the fluids flows through the upper port portion 11 to the upper channel 11 a. The other flows through the lower port portion 12 to the lower channel 12a.

After the fluid flowing through the upper flow path 11a is blown out from the upper port portion 11, the protrusion 17 causes the upper flow path 1a.
The light is reflected in the direction 1a. This reflection makes it easier for the fluid to flow, so that the flow rate of the upper flow path 11a: the flow rate of the lower flow path 12a = 1.0: 0.7 to 0.9 can be satisfied. In this case, since the fluid flows more easily, the effect of improving the Cv value is obtained. The fluid flowing through the lower flow path 12a is ejected from a gap between the lower plug 6 and the lower seat ring 8, and then reflected by the concave portion 18 so as to return to the lower plug 6. Since the reflection makes it difficult for the fluid to flow, the flow rate of the upper flow path 11a: the lower flow path 12a
Flow rate = 1.0: 0.7 to 0.9 can be satisfied. In this case, it is difficult for the fluid to flow, so that an effect of reducing the unbalance force is obtained.

In the above example, the case where either one of the convex portion 17 and the concave portion 18 is formed alone has been described.
7 and the recess 18, the flow rate of the upper flow path 11 a: the flow rate of the lower flow path 12 a = 1.0: 0.7
0.9 may be satisfied.

As described above, according to the first embodiment, since the upper and lower flow ratios can be set to appropriate values, the unbalance force is maintained at a small value in one direction over the entire range of the lift amount. can do. In addition, since the fluid flows more easily, the Cv value is improved. The Cv value is a flow rate of a fluid that can be flowed in a unit time by a unit volume of the valve device, and represents the performance of the valve device.

[0022]

As described above, according to the first aspect of the invention, the upper plug and the upper seat ring for adjusting the flow rate of the fluid to the upper flow path, and the upper plug and the upper seat ring are coaxial with the upper plug and the upper seat ring. Provided, in a valve device having a double-seat valve structure including a lower plug and a lower seat ring that adjusts the flow rate of the fluid to the lower flow path, a means for facilitating the flow of the fluid to the upper flow path is formed. In addition, since a means for preventing the fluid from flowing in the lower flow path is formed, the upper and lower flow ratio can be set to an appropriate value.

According to the second aspect of the present invention, the ratio between the flow rate of the upper flow path and the flow rate of the lower flow path, defined by the means for facilitating the flow of the fluid and / or the means for facilitating the flow of the fluid, is 1. Since the ratio is set to 0: 0.7 to 0.9, the unbalance force can be maintained at a small value in one direction over the entire range of the lift amount.

According to the third aspect of the present invention, since the means for facilitating the flow of the fluid is constituted by the convex portion formed at the lower end of the upper lid, the flow of the fluid is facilitated.
There is an effect that the v value is improved.

According to the fourth aspect of the present invention, since the means for preventing the flow of the fluid is constituted by the concave portion formed at the upper end of the lower lid, the flow of the fluid becomes difficult, so that the unbalance force is reduced. Has the effect of doing

[Brief description of the drawings]

FIG. 1 is a sectional view of a valve device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating a relationship between a lift amount and an unbalance force of the valve device according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional valve device.

FIG. 4 is a diagram illustrating an example of a relationship between a lift amount and an unbalance force in a conventional valve device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper lid 2 Lower lid 3 Valve box 4 Valve shaft 5 Upper plug 6 Lower plug 7 Upper seat ring 8 Lower seat ring 17 Convex part 18 Recess

Claims (4)

[Claims] 1. An upper plug and an upper seat ring for adjusting a flow rate of a fluid to an upper flow path, and provided coaxially with the upper plug and an upper seat ring to adjust a flow rate of the fluid to a lower flow path. A valve device comprising: a lower plug and a lower seat ring; and means for facilitating flow of the fluid formed in the upper flow path and / or means for preventing flow of the fluid formed in the lower flow path. The means for facilitating the flow of fluid and / or the means for facilitating the flow of the fluid may have a ratio of the flow rate of the upper flow path to the flow rate of the lower flow path of 1.0: 0.7 to 0.9. The valve device according to claim 1, wherein the valve device is defined. 3. The valve device according to claim 2, wherein the means for facilitating the flow of the fluid comprises a convex portion formed at a lower end portion of the upper lid. 4. The valve device according to claim 2, wherein the means for preventing fluid from flowing comprises a concave portion formed at an upper end of the lower lid.