JPH10153271A - Electric actuator for valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate possibilities that a valve seat part and the other part are damaged by excessive pressure-bonding force and leakage from the valve seat part is generated by a little pressure-bonding force with the easy adjustment. SOLUTION: In an electric actuator 1 for opening or closing a valve by the normal or reverse rotation of an output shaft 3, the normal rotation of the output shaft 3 is directly or indirectly transmitted to a stem 5 of a valve or a stem nut 6 through a coil spring 4, the stem 5 is rotated or reciprocated from the full opening position to the full closing position of the valve, the coil spring 4 is twisted by the normal rotation of the output shaft 3 also after the valve body 7 is brought in contact with a valve seat 8 and the operation of the valve body 7 is stopped, and pressure-bonding force between the valve body 7 and the valve seat 8 is increased. When the valve body 7 is rotated or reciprocated from the full closing position to the full opening position by reversely rotating the output shaft 3, the reverse rotation of the output shaft 3 is transmitted by an interlocking mechanism for directly transmitting the rotation to the stem 5 of the valve or the stem nut 6 after torsion of the coil spring 4 is restored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric actuator for a valve for opening and closing a valve mounted on a pipe for water, oil, gas or the like.

[0002]

2. Description of the Related Art Ball valves and butterfly valves open and close valves by rotating a stem. In contrast, gate valves and globe valves open and close valves by reciprocating a stem. However, in the case of a gate valve, the stem nut is rotated to reciprocate a non-rotating stem, and in the case of a globe valve, the stem is rotated to reciprocate by the action of a non-rotating stem nut.

[0003] The electric actuator for opening and closing the valve as described above rotates the stem or the stem nut in the forward or reverse direction by the rotation of the output shaft, and rotates or reciprocates the stem as described above. At the time of valve, after the valve element contacts the valve seat, the fluid cannot be completely closed unless sufficient pressure is applied between the valve element and the valve seat by this rotational or reciprocating force. There is a valve. When the contact between the valve element and the valve seat is a metal-to-metal contact, a particularly large crimping force is required. However, if the crimping force is too large, the valve seat and other parts may be damaged. If the crimping force is too small, leakage may occur from the valve seat. Needs to be adjusted appropriately.

FIG. 8 is a structural explanatory view showing a part of an example of a conventional electric actuator having a mechanism for adjusting the pressing force at such a valve seat. In the figure, a worm 51 is rotated by a gear 52 fixed to the worm receiving rotation of an electric motor via an appropriate gear train, and a worm gear 53 meshing with the worm is rotated in a direction indicated by an arrow in the figure. Then, the output shaft 54 of the actuator fixed to the worm gear 53 is rotated. This output shaft 54
Are connected to open and close a valve that has its stem rotated or reciprocated.

The worm 51 cannot move to the left in the drawing, but can move to the right. This movement to the right is supported by several disc springs 55, and The resilience of the spring 55 can be adjusted by a nut 57 screwed into the threaded rod 56.

When the valve body (not shown) of the valve comes into contact with the valve seat and stops by the actuator shown in FIG.
The worm gear 53 becomes unrotatable, and the worm 51 is rotated to exert a force to move rightward in the figure,
An attempt is made to move rightward against the repulsive elastic force of the disc spring 54. This force acts on the worm gear 53 as a reaction force, and this force increases the pressing force between the valve body of the valve and the valve seat.

The worm 51 further moves to the right, and by this movement, the limit switch 58 is operated to stop the rotation of the electric motor of this actuator, and the rotation of the worm 51 stops. However, the worm 51 is pushed to the left by the repulsive elastic force of the disc spring 55 while moving to the right, and this force acts on the worm gear 53 to cause a gap between the valve body of the valve and the valve seat. The state where the crimping force is increased is connected. This crimping force is appropriately adjusted in advance by the nut 57.

The conventional electric actuator having a mechanism for adjusting the pressing force at the valve seat portion shown in FIG. 8 is not shown in the figure, but an appropriate gear train is provided between the electric motor and the worm 51. With the worm 5 shown in the figure
1 and the worm gear 53,
These rotation axes intersect, and the structure becomes complicated and expensive.

The coned disc spring 55 for applying a pressing force between the valve body of the valve and the valve seat generates a relatively large resilient force with a relatively small compressive deformation. In order to obtain an appropriate crimping force, the work of screwing the nut 56 into the screw rod 57 to adjust the rebound resilience of the disc spring 55 is extremely delicate, and an excessive crimping force is applied to the valve seat and other parts. May be damaged, or leakage may occur from the valve seat portion by applying an excessively small crimping force.

[0010]

SUMMARY OF THE INVENTION The present invention has been developed in order to solve the problems of the conventional electric actuator having a mechanism for adjusting the crimping force at the valve seat portion. The structure is complicated and expensive, and the adjustment is extremely delicate.The valve seat and other parts may be damaged by applying excessive crimping force, or the valve seat may be damaged by applying excessive crimping force. This is to solve the problem that there is a possibility of causing leakage.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an electric actuator for opening and closing a valve by forward and reverse rotation of an output shaft. Directly or indirectly to the valve stem or stem nut via the valve to rotate or reciprocate the stem from the fully open position of the valve to the fully closed position, even after the valve element contacts the valve seat and stops the movement of the valve element , The output shaft rotates more positively and twists the coil spring to increase the crimping force between the valve body and the valve seat, while rotating the output shaft in the reverse direction moves the valve body from the fully closed position to the fully open position. When rotating or reciprocating, after the above-mentioned torsion of the coil spring is restored, the reverse rotation of the output shaft is transmitted by an interlocking mechanism that directly transmits the rotation to the stem or stem nut of the valve.

In this case, the output shaft is rotated more positively and the coil spring is twisted to increase the pressing force between the valve body and the valve seat. Adjust and set the fully closed stop cam that is adjustable and fixed to the output shaft or the shaft that works with it for
The stop position at the fully open position when the output shaft described above is rotated in the opposite direction is adjusted to the output shaft for operating the limit switch for the fully closed stop or to the shaft linked thereto so as to be adjustable. Adjust and set the cam.

Further, a coil spring connected to receive the rotation of the output shaft and a shaft connected to receive the rotation thereof and provided to directly or indirectly transmit the rotation to the stem or the stem nut are provided. Arranged on the same axis, a pin is fixed in a radial direction to one of these two axes, and a cylindrical body having a circumferential groove-shaped window on the other axis is provided with a built-in coil spring. And one of these fixings is slidable in the axial direction, and a pin is inserted into the slot-shaped window to restore when the coil spring is twisted as described above and this torsion is restored. At other times, the pin is located at one end of the slotted window due to some repulsive resilience of the coil spring, and when the coil spring is twisted as described above and when this twisting is restored, the pin is slotted. of Configured to relatively move through the.

Further, a disk is fixed to an end of the cylinder which is not fixed, and the other shaft is inserted into a hole in the center of the disk to stop the deflection of the cylinder. It is preferred that

Since the electric actuator of the present invention is constructed as described above, the positive rotation of the output shaft transmitted by the rotation of the electric motor being decelerated by the required gear train is transmitted to the coil spring connected thereto. To the stem or stem nut, thereby rotating or reciprocating the stem from the fully open position to the fully closed position of the valve, and the valve body comes into contact with the valve seat, and the rotational or reciprocating motion of the stem Is stopped. During this time, the pin fixed to one shaft remains at one end of the cylindrical window fixed to the other shaft.

The rotation of the stem or stem nut connected to the coil spring is also stopped by the contact of the valve seat, but the output shaft continues to rotate positively due to the rotation of the electric motor. As a result, the repulsive elastic force is applied to the stopped stem or stem nut, and the pressing force between the valve body and the valve seat of the valve increases. During this time, the pin fixed to one axis moves in the channel-shaped window of the cylindrical body fixed to the other axis in the direction away from one end (positive direction).

When the output shaft is rotated until the pressure at the valve seat of the valve becomes appropriate, the proper position of the output shaft or the shaft interlocked with the output shaft within one rotation between opening and closing of the valve is adjusted. The fully closed stop cam, which is adjusted and fixed in accordance with the above, operates the fully closed stop switch to stop the electric motor. The state where the crimping force of the valve seat is increased is connected to prevent leakage.

Next, when the output shaft rotates in the opposite direction due to the rotation of the electric motor, the torsion of the twisted coil spring is gradually restored, and the crimping between the valve body and the valve seat of the valve caused by the torsion is performed. Power gradually decreases. During this time, the pin secured to one axis moves in the opposite direction through the cylindrical channel-shaped window secured to the other axis until it abuts one end of the window. In the above description, the pin has been described as reciprocating in the window of the cylindrical body, but the actual movement may be the pin or the window of the cylindrical body depending on the structure. Go to

Since the reverse rotation of the electric motor continues, the pin fixed to the output shaft by the rotation of the output shaft may be connected to one end of the window of the cylindrical body or one end of the window of the cylindrical body fixed to the output shaft. The valve is opened by rotating the stem or stem nut in the opposite direction by pushing the pin and not by the coil spring but by the interlocking mechanism that transmits the reverse rotation of the output shaft directly to the stem or the stem nut of the valve. . Therefore, the coil spring is not subjected to the torsion in the opposite direction, and the torsion load is applied only in one direction. Unlike the case where the forward / reverse torsion load is applied, fatigue fracture is unlikely to occur.

When the valve is fully opened, a full-open stop cam, which is adjustable and fixed to the output shaft or an axis that rotates within one rotation between opening and closing of the valve in conjunction with the output shaft, activates a full-open stop switch. Then, the electric motor is stopped. This cam is naturally pre-adjusted to an optimal position.

In the above-mentioned cylindrical body, one shaft is inserted into a hole in the center of the disk body fixed thereto, and the shaft is prevented from swinging. Therefore, when the cylindrical body is rotated by the pin as described above, this cylindrical body is rotated. The body is prevented from swinging and applying a bending force to the other axis to which the cylinder is fixed.

[0022]

FIG. 1 is a longitudinal sectional view showing a globe valve equipped with an embodiment of an electric actuator of the present invention.
FIG. 2 is a structural explanatory view of the globe valve with the electric actuator shown in FIG. Hereinafter, the structure and operation of the embodiment of the present invention will be described with reference to these drawings and FIGS. 3 to 7 described later.

1 and 2, 1 is an electric actuator, 2 is a globe valve, 3 is an output shaft, 4 is a coil spring, 5 is a stem, 6 is a stem nut, 7 is a valve body, 8 is a valve seat, 9 Is a pin, 10 is a cylindrical body, 11 is a groove-shaped window of the cylindrical body 10, 12 is a disk body, 13 is a limit switch for fully closing stop, 14 is a cam for completely closing stop, and 15 is a fully opening stop A limit switch 16 is a cam for fully stopping the opening.

In the electric actuator 1, the rotation of the electric motor 17 is transmitted to the output shaft 3 via the gear train 18, and the valve 2 is opened and closed by the forward and reverse rotation of the output shaft 3. First, a positive rotation of the output shaft 3, that is, a clockwise rotation as viewed from above in the illustrated embodiment is a positive rotation, and this rotation is slidably and non-rotatably mounted on the output shaft 3. 19, this disk 19 and stem 5
The coil spring 4 is mounted between the disk 20 and the disk 20 fixed to the disk 20 with the both ends 4a and 4b fixed to the disks 19 and 20, respectively. Rotate to rotate stem 5 positively.

The stem nut 6, into which the stem 5 is screwed, is fixed to the yoke 2a of the valve 2, and the stem 5 moves downward (reciprocates) by positively rotating.
Then, the valve body 7 also moves downward and contacts the valve seat 8, and cannot move any more, and stops. FIG. 1 shows a state in which the valve element 7 is in contact with the valve seat 8, and FIG. 2 shows a state before the stem 5 and the valve element 7 move downward.

The pin 9 is fixed to the outer periphery of the disk 19,
A cylindrical body 10 is fixed to a disk 20.
The pin 9 is inserted into the window 11 in a circumferential groove shape provided in the above, and before the above-described output shaft 3 rotates positively and until the valve body 7 comes into contact with the valve seat 8 by positive rotation. The pin 9 is located at one end (11a in FIGS. 3 and 4 described below) of the groove-shaped window 11 by a repulsive elastic force given to the coil spring 4 in advance.

FIG. 3 is an external perspective view of the above-mentioned cylindrical body 10, in which the pin 9 is in contact with one end 11a of the groove-shaped window 11 as described above. FIGS. 4 to 6 are explanatory perspective views showing three states in an operation stage in order to explain the operation of the present embodiment by seeing through the inside of the cylindrical body 10 shown in FIG. The external shape of the cylindrical body 10 is shown using a two-dot chain line. Note that the reference numerals used in FIGS.
1 and 2 are common.

FIG. 4 shows a state before the output shaft 3 starts positive rotation. FIG. 5 shows that the rotation of the output shaft 3 is
9, stem 5 via coil spring 4 and disc 20
Is rotated, the stem 5 is screwed into the stem nut 6 and descends, and the valve body 7 is brought into contact with the valve seat 8 as shown in FIG. , The coil spring 4, the disk 19 and the cylindrical body 10 are also lowered.

In this state, the output shaft 3 continues to rotate further, so that the coil spring 4 moves the valve 7 to the valve seat 8.
The coil spring 4 is twisted between the disk 20 that has been unable to rotate due to contact with the disk 20 and the disk 19 that is rotated by the output shaft 3, and the rebound resilience of the coil spring 4 increases. The crimping force with the seat 8 is increased. During this time,
The pin 9 fixed to the outer periphery of the disk 19 rotates together with the output shaft 3 and moves away from one end 11 a in the groove-shaped window 11 of the cylindrical body 10.

When the output shaft 3 rotates until the crimping force between the valve body 7 and the valve seat 8 becomes appropriate, the output shaft 3 shown in FIG.
The fully closed stop cam 14 fixed to the shaft 21 that rotates within one rotation during opening and closing of the valve 2 in conjunction with the operation of the fully closed stop switch 15 and the electric motor 17
To stop.

The crimping force between the valve body 7 and the valve seat 8 is maintained in that state to prevent leakage of the fluid, and the cam 14 for fully closing and stopping is adjusted so that the crimping force is appropriate. The fixing position has been adjusted in advance. FIG. 6 shows the state at this time.

Next, when the output shaft 3 rotates in the reverse direction due to the rotation of the electric motor 17, the torsion of the coil spring 4 being twisted is gradually restored, and the crimping force between the valve body 7 and the valve seat 8 is gradually increased. Decrease. Meanwhile, the pin 9 fixed to the disk 19 is connected to the groove-shaped window 1 of the cylindrical body 10 fixed to the disk 20.
1 moves in the opposite direction until it comes into contact with one end 11a. FIG. 5 shows the state at this time.

Since the rotation of the output shaft 3 continues further, the disk 19
The pin 9 fixed to the cylindrical body 10 pushes one end 11a of the grooved window 11 of the cylindrical body 10 so that the reverse rotation of the output shaft 3 is not performed through the coil spring 4 but through the cylindrical body
Is rotated, the stem 5 is rotated in the opposite direction, and the stem 5 is pulled out from the fixed stem nut 6, and the valve 2 is opened.

Therefore, the coil spring 4 is not subjected to reverse rotation torsion, and the torsional load is applied in only one direction. Unlike the case where forward and reverse torsional loads are applied, fatigue failure is unlikely to occur. .

When the valve 2 is fully opened, the shaft 21 rotates within one rotation between opening and closing of the valve 2 in conjunction with the output shaft 3.
The fully open stop cam 14 which is adjustable and fixed to the actuator activates the fully open stop limit switch 15 and the electric motor 1
7 is stopped. The cam 14 is naturally adjusted to an optimum position in advance. FIG. 4 shows the state at this time.

The cylindrical body 10 has a disk body 12 fixed thereto.
Since the output shaft 3 is inserted into the hole 12a at the center of the cylindrical body, when the cylindrical body 10 is rotated by the pin 9 as described above, the cylindrical body 10 swings, and the cylindrical body 10 is fixed via the disk 20. This prevents the stem 5 from being subjected to bending force.

FIG. 7 is a structural explanatory view showing another embodiment. Unlike the embodiment shown in FIGS. 1 to 6, a disk 20 is fixed to the output shaft 3, and this disk 20 A cylindrical body 10 is fixed, and a disk 19 is slidably and non-rotatably mounted on the stem 5. A pin 9 is fixed to the disk 19, and the pin 9 is provided on the cylindrical body 10. When the valve 2 is opened, the grooved window 11 of the cylindrical body 10 pushes the pin 9 to rotate the stem 5 when the valve 2 is opened.

[0038]

As described above, the electric actuator according to the present invention has a mechanism for adjusting the crimping force at the valve seat, and its structure is simple and cost can be reduced. It is easy to adjust, and there is no danger of damaging the valve seat and other parts by applying excessive crimping force, or causing leakage from the valve seat by applying too small crimping force. Has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a globe valve to which an embodiment of an electric actuator according to the present invention is mounted.

FIG. 2 is a structural explanatory view of a globe valve with an electric actuator shown in FIG. 1;

FIG. 3 is an external perspective view showing a cylindrical portion of the embodiment shown in FIGS. 1 and 2;

FIG. 4 is an explanatory perspective view showing a state at an operation stage by seeing through the inside of the cylindrical body shown in FIG. 3;

5 is an explanatory perspective view showing a state of an operation stage by seeing through the inside of the cylindrical body shown in FIG. 3;

FIG. 6 is an explanatory perspective view showing a state of an operation stage by seeing through the inside of the cylindrical body shown in FIG. 3;

FIG. 7 is a structural explanatory view showing another embodiment.

FIG. 8 is a structural explanatory view showing a part of an example of a conventional electric actuator having a mechanism for adjusting a pressing force at a valve seat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric actuator 2 Globe valve 3 Output shaft 4 Coil spring 5 Stem 6 Stem nut 7 Valve 8 Valve seat 9 Pin 10 Cylindrical part 11 Slotted window 11a One end 12 Disc 12a Center hole 13 Fully closed stop Limit switch 14 Fully closed stop cam 15 Fully open stop limit switch 16 Fully open stop cam 21 Axis linked to output shaft

Claims (4)

[Claims] An electric actuator for a valve for opening and closing a valve by forward and reverse rotation of an output shaft, wherein the positive rotation of the output shaft is directly or indirectly transmitted to a stem or a stem nut of the valve via a coil spring. After the valve is rotated or reciprocated from the fully open position to the fully closed position of the valve, and the valve body contacts the valve seat and the movement of the valve body stops,
The output shaft rotates more positively and twists the coil spring to increase the crimping force between the valve body and the valve seat, while rotating the output shaft reversely rotates the valve body from the fully closed position to the fully open position An electric actuator for a valve, characterized in that when the coil spring is to be moved or reciprocated, the reverse rotation of the output shaft is transmitted by an interlocking mechanism that directly transmits the reverse rotation of the output shaft to the stem or stem nut of the valve after the torsion of the coil spring is restored. . 2. The method according to claim 1, wherein the output shaft is further positively rotated to twist the coil spring and increase the pressure between the valve body and the valve seat to operate the limit switch for fully closing the valve. Adjusting and setting the fully closed stop cam that is adjustably fixed to the output shaft of the output shaft or the shaft interlocking with the output shaft, the stop position at the fully open position when the output shaft is rotated in the reverse direction is set to the full stop position. 2. An electric actuator for a valve according to claim 1, wherein a fully open stop cam is adjustably fixed to an output shaft for operating a limit switch for closing and closing or a shaft interlocked with the output shaft. 3. A coil spring connected to receive rotation of the output shaft, and a shaft connected to receive rotation of the coil spring and provided to directly or indirectly transmit the rotation to a stem or a stem nut. Are arranged on the same axis, a pin is fixed radially to one of these two axes, and a cylindrical body having a circumferential groove-shaped window on the other axis is provided with a coil spring. Built-in and fixed, and one of these fixed parts is slidable in the axial direction, and a pin is inserted into the grooved window, except when the coil spring is twisted and when this torsion is restored. The pin is located at one end of the channel-shaped window due to the repulsive elastic force of the coil spring, and the pin moves relatively in the channel-shaped window when the coil spring is twisted and when this twist is restored. 3. The method according to claim 1, wherein
An electric actuator for a valve according to the above. 4. A disk is fixed to an end of the cylindrical body that is not fixed, and one of the shafts is inserted into a hole at the center of the disk so as to stop the deflection of the cylindrical body. An electric actuator for a valve according to any one of claims 1 to 3.