JPH10159997A - 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 is directed through an upper port 11 into an upper passage 11a, while the lower flow is directed through a lower port 12 into a lower passage 12a. The sectional area of the lower passage 12a is made smaller than that of the upper passage 11a to set 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. 4 is a sectional view showing a conventional valve device, in which 1 is an upper cover of a valve device, 2 is a lower cover, and 3 is 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 flow path 11a through the upper port section 11, and flows through the lower flow path 12a through the lower port section 12. 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 unbalanced force of the fluid due to the upward and downward flows. However, as can be seen from FIG. 5 showing an example of the relationship between the lift amount and the unbalance force, the unbalance force is such that the lift amount is 0 to 50.
Up to% works in the positive direction (the direction to open the valve),
When the lift amount exceeds 50%, it suddenly turns to the minus direction (the direction to close the valve) and continues to increase to 100%.
In FIG. 5, the unbalance force changes from the plus direction to the minus direction at the point where the lift amount is 50%. Is the case where the lift amount is in the range of 30 to 50%.

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 for controlling an upper plug and an upper seat ring for adjusting a flow rate of a fluid to an upper passage, and coaxially with the upper plug and the upper seat ring. Provided in the valve device having a double-seat valve structure including a lower plug and a lower seat ring for adjusting the flow rate of the fluid to the lower flow path, the flow rate of the lower flow path of the upper flow path The value is smaller than the flow rate.

According to a second aspect of the present invention, the flow rate ratio between the upper flow path and the lower flow path is 1.0: 0.7 to 0.9.

According to a third aspect of the present invention, the cross-sectional area of the upper flow path is formed smaller than the cross-sectional area of the lower flow path.

According to a fourth aspect of the present invention, there is provided the valve device, wherein the center line of the flow path on the inflow side is positioned lower than the center line of symmetry of the valve device connecting the center of the inlet and the center of the outlet. A plug and the lower plug are provided.

[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.

In the first embodiment, the lower flow path 1
2a is formed so that the flow rate of the fluid flowing therethrough is smaller than the flow rate of the fluid flowing through the upper flow path 11a by a predetermined value.

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 from the inflow port 9 flows through the upper flow path 11 a through the upper port section 11, and flows through the lower port section 12. And flows through 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 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 1.0: 0.7 to 0.
9 is set.

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 cross-sectional area of the lower flow path 12a is set smaller than the cross-sectional area of the upper flow path 11a by a predetermined value. 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 and the upper channel 11a. The other flows through the lower port section 12 and the lower flow path 12a. At this time, the upper channel 11
flow rate of a: flow rate of lower flow path 12a = 1.0: 0.7 to
The upper channel 11a and the lower channel 12a are formed such that 0.9 is satisfied.

For example, the upper channel 11a and the lower channel 1
2a is formed so that the ratio of its cross-sectional area is 1.0: 0.7 to 0.9, so that the flow rate of the upper flow path 11a: the flow rate of the lower flow path 12a = 1.0: 0.7. 0.9 can 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.

Embodiment 2 FIG. 3 is a cross-sectional view of a valve device according to Embodiment 2 of the present invention, in which 1 is an upper lid, 2 is a lower lid, 3 is a valve box, 4 is a valve shaft, 5 is an upper plug,
6 is a lower plug, 7 is an upper seat ring, 8 is a lower seat ring, 9 is an inlet, 10 is an outlet, 11 upper port section, 12 is a lower port section, 11a is an upper flow path, and 12a is a lower flow path. It is a side channel. Since these are the same as or equivalent to those shown in FIG. 1, the description is omitted. Reference numeral 31 denotes a center line of symmetry of the valve device according to the second embodiment, and reference numeral 32 denotes a center line between the upper plug 5 and the lower plug 6 in a fully closed state.

In the second embodiment, the upper plug is positioned such that the center line 32 of the flow path on the inflow side is lower than the center line 31 of the valve device connecting the center of the inlet 9 and the center of the outlet 10. 5 and a lower plug 6 are provided. As a result, the cross-sectional area of the lower flow path 12a is smaller than the cross-sectional area of the upper flow path 11a by a predetermined value. By appropriately setting this predetermined value, 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.

Next, the operation will be described. 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 and the upper channel 11a. The other flows through the lower port section 12 and the lower flow path 12a. At this time, since the cross-sectional area of the lower flow path 12a is smaller than the cross-sectional area of the upper flow path 11a by a predetermined value, the flow rate of the upper flow path 11a: the flow rate of the lower flow path 12a = 1.0: 0.7. ~ 0.9
Is satisfied.

As described above, according to the second 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.

[0024]

As described above, according to the first aspect of the present invention, the upper plug and the upper seat ring for adjusting the flow rate of the fluid to the upper flow path, and coaxially with the upper plug and the upper seat ring. In a valve device having a double-seat valve structure provided with a lower plug and a lower seat ring for adjusting a flow rate of a fluid to a lower flow path, the flow rate of the lower flow path is a flow rate of the upper flow path. Since it is configured to have a smaller value, there is an effect that the unbalance force can be maintained at a small value in one direction over a wide range of the lift amount by setting the upper and lower flow ratios to appropriate values.

According to the second aspect of the present invention, the flow rate ratio between the upper flow path and the lower flow path is 1.0: 0.7 to 0.9. There is an effect that the unbalance force can be maintained at a small value in one direction over the whole.

According to the third aspect of the present invention, the cross-sectional area of the upper flow path is made smaller than the cross-sectional area of the lower flow path. By achieving the flow rate of the side flow path = 1.0: 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 fourth aspect of the present invention, the upper plug and the upper plug are arranged such that the center line of the flow path on the inflow side is lower than the center line of symmetry of the valve device connecting the center of the inflow port and the center of the outflow port. Since the lower plug is provided, the flow rate of the upper flow path: the flow rate of the lower flow path = 1.0:
By achieving 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.

[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 of a valve device according to Embodiment 2 of the present invention.

FIG. 4 is a sectional view showing a conventional valve device.

FIG. 5 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 11 Upper port part 12 Lower port part 31 Symmetry center line of valve device main body 32 Upper part in fully closed state Center line between plug 5 and lower plug 6

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, wherein the flow rate of the lower flow path is smaller than the flow rate of the upper flow path. 2. The flow rate ratio between the upper flow path and the lower flow path is 1.0:
2. The valve device according to claim 1, wherein the value is 0.7 to 0.9. 3. The valve device according to claim 2, wherein a cross-sectional area of the upper flow path is smaller than a cross-sectional area of the lower flow path. 4. The upper plug and the lower plug are provided such that the center line of the flow path on the inflow side is located lower than the center line of symmetry of the valve device connecting the center of the inflow port and the center of the outflow port. 3. The valve device according to claim 2, wherein: