JPS587867B2 - Kaitenben ni Okeru Rotsukingouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of sealing a rotary valve having a locking device for high-pressure fluid used in a water turbine inlet valve or the like.

Conventionally, when repairing or inspecting a water turbine located downstream of the inlet valve, the valve body is closed, the hydraulically operated seal ring is operated until it reaches its fully closed position, and then mechanically operated. It was locked by pushing in the locking bolt.

That is, the seal locking bolt was set so that when the valve body was in the fully closed position, it would come into contact with the back surface of the seal ring while water pressure was present on the valve body and on the downstream side.

For this reason, the conventional locking device has the disadvantage of being large because it supports the entire hydraulic thrust acting on the inside diameter of the pipe.

In order to improve this drawback, a mechanism is created in which an appropriate amount of gap is calculated in advance between the back of the seal ring and the locking bolt, and only a portion of the elastic displacement of the valve body is supported by the locking bolt and converted into sealing force. The present inventor proposed this in Japanese Patent Application No. 48-116897.

However, in this setting method, all the 10 to 20 locking bolts provided around the entire circumference of the seal must be set at uniform intervals from the back surface of the seal ring, and the setting operation requires a long time.

If a slight adjustment error occurs in the gap setting of each locking bolt, the seal surface pressure applied to the seat surface will become large due to the large spring constant of the valve mechanism, resulting in a partial load difference on the seal surface, resulting in a good seal. Requires redoing several sets to obtain water action.

In addition, the deflection (elastic displacement amount) of the valve body changes due to a decrease in the overall spring constant of the valve body and valve stem due to wear over time of the valve body bearing material, the valve stem, and the valve body itself. Since the setting position of the locking bolt is set more closely, the set gap amount when setting the locking bolt becomes inappropriate after a period of time, and there is a drawback that a sufficient sealing effect cannot be obtained.

The present invention has been made in an attempt to improve the above-mentioned drawbacks.
The purpose is to simplify the gap setting for the seal ring of the locking device.

That is, the features of the present invention include a step of closing a valve body housed in a valve body, a step of constantly applying pressure to the sealing surfaces upstream and downstream of the closed valve body and bringing the seal ring into contact with the valve body, and a step of closing the valve body housed in the valve body. a step of bringing the seal ring into contact with the opposite side surface of the seal ring and fixing the locking device of the seal ring to the valve body at this contact position; a step of discharging water from the inside of the valve body to the outside of the valve body; The present invention provides a sealing method for a rotary valve having a locking device in which the valve body is further flexed by the discharge of water, the seal ring moves to follow the flexure of the valve body, and a gap is formed between the lock device and the seal ring.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a seal guide 2 and a water conduit 4 are attached to a valve body 1.
A seal ring 3 is provided between them.

When the valve body 5 is fully closed, the seal ring 3 is operated by the seal closing hydraulic pressure transmitted through the hydraulic pressure transmission pipe 30, and is pressed against the valve seat 6 fixed to the valve body 5 to perform a sealing action.

The valve body 5 is fixed to a valve shaft T operated by a servo motor 8, and is rotatably housed within the valve body 1.

The seal sleeve 9 is attached to the inside of the valve body 1, and together with the seal guide 2 constitutes a cylinder 10 that guides the seal ring 3 during opening and closing movement.

The valve body 1 is provided with a drain valve 19 for draining water within the valve body 1 and an air valve 20.

Note that 4a is a flange of the water conduit pipe 4.

The locking device in the rotary valve constructed as described above will be explained in detail with reference to FIG.

The seal ring 3 housed in the cylinder 10 is moved in the closing direction (
(to the right), and is moved to the opening direction (to the left) by the hydraulic pressure supplied through the opening operation hydraulic pressure supply port 11b.

The hydraulic pressure is supplied sequentially or manually after the rotation of the valve body 5 is completed.

A plurality of threaded sleeves 13 are attached to the flange 4a of the water pipe 4.
is attached, and a locking bolt 14 is screwed into this threaded sleeve 13.

Lubricating oil is supplied to the threaded portion from an oil supply port 12.

One end of the locking bolt 14 passes through the seal guide 2 and is opposed to the seal ring 3, and the other end projects outside the flange 4a of the water conduit 4.

The protrusion includes a lock nut 15 and a scale ring 16.
is attached, and a spanner hook 17 is provided on the bolt head, and a pointer 18 is attached to the water conduit 4 facing the scale ring 16.

Next, the operation when closing and locking the valve body 5 of the rotary valve will be explained.

This will be explained with reference to FIG. 1 and FIG. 3 at the same time.

Note that since the elastic displacement of the valve body is larger than the elastic displacement of the valve stem, the displacement of the valve stem will be ignored to simplify the explanation.

When the valve is closed, when the servo motor 8 is driven, the valve body 5 rotates via the valve shaft T, and is closed by rotating 900 revolutions.

At this time, the seal ring 3 is not yet closed, so the pressure inside and outside the valve body 5 is P1 = P2 = P3. However, due to the action of pressure P3, a load F4 acts on the valve shaft 7, and the valve body 5 Flex to the position shown in Figure 3 C.

Next, hydraulic pressure is supplied to both the upstream and downstream cylinders 10 through the hydraulic pressure transmission pipe 30, and the upper and downstream seal rings 3 are pushed toward the closing side (rightward in FIG. A pressure difference is made between the two ports 6 to perform a sealing action.

At this time, the valve body receives pressure from the seal ring 3 and is subjected to a load F.
1, F1', F2, and F2', it is bent to the position D in FIG.

By compressing the seal ring 3 to the valve seat 6, the downstream pressure P2 is reduced, but the downstream valve element is also deformed into the same shape as the upstream valve element due to the load F1 generated by the upstream pressure P1.

A load is generated in the F4 direction due to the load F1, and the valve body 5 is extended in the direction of the valve shaft 7, and the valve body 5 is deformed to minimize the change in the circumference of the cylinder.As a result, the downstream valve body is also displaced in the same way as the upstream valve body.

Next, a spanner is applied to the spanner hook 7 on the head of the locking bolt 14, and the locking bolt 14 is rotated until its tip contacts the seal ring 3.

After that, the locking bolt 14 is tightened by the lock nut 15.
fix the position.

After the second position is determined in this way, the drain valve 19 and the air valve 20 are opened to drain the water in the valve body 1 and the valve body 5.

Since the pressure that existed inside the valve body 5 disappears, the valve body 5 receives the force from the upstream and downstream water pressures acting from the outside and the seal ring 3, and is further bent from the second position to the second position.

The seal ring 3 moves following the deflection of the valve body 5, and a gap is formed between the locking bolt 14 and the back surface of the seal ring 3.

That is, the amount of deflection L1 of the valve body 5 is automatically given without being set in advance according to the spring constant (rigidity) of the valve body and the valve stem.

Here, A, 2, the opening shown in FIG. 3, the valve body 5, the valve stem T,
The positional relationship between the seal ring 3 and the lock bolt 14 will be described again.

Position A is the position when the valve body 5 is under no pressure, that is, when there is no liquid in the water conduit 4 or the valve body, and the amount of deflection of the valve body 5 is zero.

This is a state in which the valve body 5 has a perfect circular shape as manufactured.

Position 2 is when the inside, upstream and downstream of the valve body 5 are filled with liquid, and the seal ring 3 is pressed against the valve body 5.

When the tip of the seal ring 3 is in the second position, the locking bolt 14 is screwed in until it contacts the seal ring 3, and is fixed at the contact position.

Position Cl (t) is the deflection point of the valve body and valve stem when the upper and downstream seals are closed and the inside of the valve body is drained, and indicates the maximum deflection of the valve body due to the upper and downstream water pressure.

The distance between B and D is L1.

When the rotary valve is closed, the valve body 5 is held at a position somewhere between 2 and 4 in FIG. 3 by draining water from inside the valve body 5.

The seal ring 3 is pressed against the valve seat 6 of the valve body 5.

In this state, the sealing pressure of the seal ring 3 disappears,
Consider an emergency situation in which the sealing action is no longer performed properly.

A possible example of the loss of sealing pressure in the seal ring 3 is a breakage of the hydraulic pressure transmission pipe 30.

At this time, water flows into the inside of the valve body 5 and the pressure is P1=P2
= P3, and the valve body 5 passes through the second position and attempts to restore its deflection to the position C.Here, the second position is defined by the internal pressure P3 of the valve body 5 and the pressure from above and downstream of the valve body 5. External pressure P1, P
This is the position when the load F2 from the seal ring 3 is further applied.

In the emergency situation, the sealing pressure of the seal ring 3 is gone, so naturally the valve body 5 does not stay at the 2nd position but also tries to expand to the 3rd position.

The distance between C and B is L2.

If the locking bolt 14 were not present, the valve body 5 would actually bulge and restore to the position C, but since the movement of the seal ring 3 is limited by the locking bolt 14, the valve body 5 would be a backup for the locking bolt 14. Therefore, the deflection amount L1 at position 2 is maintained.

As a result, (L2-Ll) acts on the seat surfaces of the seal ring 3 and the valve seat 6 as a tightening margin for the locking bolt 14, a load corresponding to this amount of deflection is generated, and the contact surface pressure due to this load prevents the sealing action. It will be done.

That is, if the spring constant of the valve body 5 is K, then the seal load P=K(L2-L1).

The operation of the present invention will be explained with reference to FIG. 3 again.

D1 is the inner diameter of the seal ring 3, and D2 is the outer diameter.

D4 is the diameter of the valve stem 7. P1, P2, and P3 are the upstream pressure of the valve body, the downstream pressure of the valve body, and the pressure inside the valve body, respectively.

F1 is the force with which the water on the upstream side of the valve body pushes the valve body, and F1' is the force with which the water on the downstream side of the valve body pushes the valve body.

F2tF2' is the force applied to the back of the seal ring, the first
As shown in the figure, the upstream pressure P1 is
is acting, so .

F3 is the internal pressure load acting on the valve body, It is.

F4 is the load acting on the valve stem diameter, It is.

Among the above-mentioned loads F1 to F4, the ones that act to crush the valve body from the shape shown by the two-dot chain line to the shape shown by the one-dot chain line in Fig. 3 (this is considered a positive load) are F1 and F
1', F2, F2', and F4.

Conversely, F3 acts to change the shape of the valve body from the one-dot chain line shape to the two-dot chain line shape (this is considered a negative load).
It is.

The following table shows how the positive load and negative load act at each of the valve body positions A, B, C, and 2 in FIG. 3.

In (a), neither a positive load nor a negative load is acting, so there is no deflection of the valve body.

Also, when comparing (c) and (d), (d) has a higher F2
, F2', the positive load is large, so it can be seen that the deflection is also large.

According to the present invention, the gap setting operation for the Zeel ring of the locking device of the rotary valve is easy, and the spring constant of the valve body and valve stem changes due to wear of the valve stem, valve bearing metal, valve body, etc. due to aging. Even if the settings are not correct, the settings will be locked to the initially set optimal state.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a rotary valve having a locking device of the present invention, FIG. 2 is an enlarged detailed view of the locking device, and FIG. 3 is a diagram explaining the principle. 1...Valve body, 2...Wool guide, 3...Seal ring, 5...Valve body, 6...Valve seat, 14...
- Locking bolt.

Claims (1)

[Claims] 1. A step of closing the valve body housed in the valve body, a step of constantly applying pressure to the upstream and downstream sealing surfaces of the closed valve body and bringing the seal ring into contact with the seal ring, and a seal ring that comes into contact with the sealing surface of the valve body. a step of bringing the seal ring into contact with the opposite side and fixing the locking device of the seal ring to the valve body at this contact position; a step of discharging water from the inside of the valve body to the outside of the valve body; A method for sealing a rotary valve having a locking device, characterized in that the seal ring moves to follow the deflection of the valve body, and a gap is formed between the lock device and the seal ring.