JPS6134583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a force control device used for a valve actuation rod,
and particularly relates to such a device in which the actuator generates a maximum tension force that is less than the force that would normally occur on the piston of the valve actuator in combination with the actuating rod when the valve is placed in a back seated position.
In the past, several devices have been used to close large valves in power plant water and steam systems.
It is currently believed that a valve actuator with a hydraulic cylinder and gas accumulator provides an excellent device for quickly closing these valves. Hydraulic fluid is supplied to the piston inside the hydraulic fluid cylinder to open the valve against a source of pre-charged high pressure gas acting on the other side of the piston. High pressure gas is charged into the accumulator to ensure that there is a sufficient amount of high pressure gas acting on the piston to quickly close the valve when high pressure is released.

Although this device generates the correct force to open and close the valve, the dimensions of such actuator and the pressure required create a large tension force acting on the actuating rod when the valve is open and seated. It turned out that it is possible. Accordingly, various force limiting devices in the form of couplings between the actuating rod and the valve stem have been utilized in the past to protect the valve during back seating. While these devices have reliably limited tension, they have required additional components, thus adding to the cost of the valve-actuator device. There was a need to produce a simple, reliable, and inexpensive device for using such a valve actuator that would ensure that the valve would not be damaged during back seating.

It is therefore an object of the present invention to provide a device for limiting the forces acting on the actuating rod that does not require a force limiting coupling between the actuating rod and the valve stem.

Another object of the invention is to provide a force limiting device of the type described which is safe, reliable and relatively inexpensive to manufacture.

These and other objects of the invention are:
selectively supplied to the cylinder at a first side of the piston arrangement mounted inside the cylinder and coupled to the actuating rod when fluid from a second source acts in an opposite direction at a second side of the piston arrangement; This is achieved by a preferred embodiment of the type of device for limiting the force acting on the actuating rod of a valve actuator of the type containing actuating fluid from a first source and discharged from said cylinder. The piston device has a central recess, said recess comprising a cylindrical hole having a decreasing diameter at an opening formed in a first side of said piston device, said opening thus has a smaller cross-sectional area than the hole. An actuating rod is slidably received within the opening and extends from the first side of the piston arrangement through the bore in the first end of the cylinder, and the actuating rod is disposed on the outside of the cylinder and has an actuating rod connected to the valve stem. terminating at an extended end. The inner cylindrical shape is such that an enlarged piston head is fixed at its first side to the other end of the working rod and is retained within the cylindrical bore by a portion of the piston device around the opening. placed inside the hole. The piston head is in sliding sealing contact with the interior of the cylindrical bore for limited axial movement. Apparatus is provided for applying fluid pressure to the second side of the piston head from a third source different from the first and second sources in communication with the cylindrical bore. The working fluid which produces the pressure acting on the piston head is held opposite the piston stop at the second end of the cylinder by the working fluid which produces a force on the piston arrangement which is greater than the maximum tension force. When the actuating rod is in position, it is subjected to an opposing force by a predetermined fluid pressure that creates a maximum tension on the actuating rod.

As can be seen in FIG. 1, a prior art valve actuator 10 without any type of idler includes a hydraulic cylinder 12 mounted on a yoke 14 of a valve 16. A piston 18 is slidably mounted within the hydraulic cylinder 12 and includes an actuation rod 20 . Actuation rod 20 extends from first side 22 of piston 18 through an opening 24 in first end 26 of cylinder 12 . Actuation rod 20 has an extended end 28 . Extended end 28 is coupled to valve stem 32 by a coupling device 30.

The valve stem 32 extends through the packing 33 of the bonnet 34 of the valve 16 to actuate the closure member 36 of the valve 16, in this case the gate device. As shown, piston 18 and thus closure device 36 are in the open position.

Prior art valve actuator 10 further includes an accumulator 38 . Accumulator 38 is preferably of spherical design and includes a pressure wall 40 . Cylinder 12 traverses through an opening 42 in pressure wall 40 . Cylinder 12 is fixedly and sealingly coupled to pressure wall 40 and is disposed opposite pressure wall 40 to include a second end 44 . The second end 44 is located within an interior portion 46 of the accumulator 38 . The second end 44 of the cylinder 12, in this prior art embodiment, directs the high pressure gas within the interior portion 46 of the accumulator 38 to the second end of the piston 18.
It is open to act on the side 48.

During normal valve operation, working fluid is supplied to the interior of the cylinder 12 through the access hole 50 and the piston 1
8 thereby causing the piston 18 to move axially against the high pressure gas of the accumulator 38 until the valve 16 assumes the open position as shown in FIG. When it is desired to close the valve 16, the working fluid within the cylinder 12 is rapidly released through the access hole 50 and high pressure gas acts on the second side 48 of the piston 18 to close the piston 18. move axially in the direction.

As disclosed above, although the prior art valve actuator 10 provides a reliable device for opening and closing the valve, the relatively high stiffness of the coupling 30 acts on the piston 18. forces on the closure device 36, damage to the valve can occur while the valve is back seated if the pressures of the working fluid and propellant are not accurately maintained. Moreover, it will be appreciated that if high pressure gas in the accumulator were to escape due to leakage or destruction of the accumulator, any means of limiting the force applied to the back seat of the valve would be significantly complicated. Accordingly, some valve actuators of this type include a partial closure member above the second end 44 of the cylinder 12 to limit upward movement of the piston 18 when the valve 16 is in the open position. has been improved. However, the distance between the closure member at the second end 44 and the back seat of the valve 16 cannot be manufactured well within acceptable tolerances to ensure that excessive forces are not exerted on the back seat. . It is clear that the actuation rod 20 and valve stem 32 extend and retract so that the piston 18 faces the closure member and the actuation rod 20 and valve stem 32 move the closure element, i.e. the closure member 36, to the back seated position. If it is too long, all of the force due to the working fluid will be acting on the back seat, or potentially no force will be acting on the back seat.

Therefore, the coupling device 3 shown in FIG.
Coupling devices different from zero have been used in the past. These devices (not shown) include the piston 18
to be sufficiently seated opposite the closure member at the second end 44 of the cylinder 12, while transmitting a predetermined force to the valve stem 32 to provide the proper spacing and pressure to seat it in the back seat. Some type of spring or deflection device is used to provide free movement. The present invention is intended to replace such coupling devices, and allows for the use of simpler and more directly acting coupling devices such as coupling device 30, while providing a suitable back seat connection. This makes it possible to sit down.

As can also be seen from FIG. 1, which shows a prior art valve actuator 10, this actuator has features that ensure that hydraulic fluid, i.e., hydraulic oil, does not leak into the interior portion 46 of the accumulator 38. are doing. For this purpose,
Generally, the piston 18 includes a pair of seal rings 52, but in the event that the seal ring 52 adjacent to the first side 22 leaks working fluid, the other seal ring 52 will prevent the working fluid from leaking. is configured to prevent leakage. Accordingly, a radially extending passageway 54 communicates the space between the pair of seal rings 52 with an axial passageway 56 in the actuating rod 20. The passage 56 is the operating rod 20
extends to an extended end 28 and terminates in an attachment 58 . Attachment 58 is adapted to be selectively openable to the atmosphere. Therefore, in the event of a leak as described above, working fluid will pass through passage 54 and axial passage 56 and be vented to the atmosphere via attachment 58. The inner side 46 of the accumulator 38 is maintained at a significantly higher pressure than these passages, so that no working fluid can leak through the sealing ring 52 adjacent the second side 48 of the piston 18.

As shown in FIG. 2, the above-mentioned cylinder 12
A preferred force limiting device 60 can be used with a valve actuator 62 having a cylinder 64 similar to that shown in FIG. Unless otherwise indicated, the various elements of actuator 62 are identical to the previously described elements of actuator 10 according to the prior art.

Force limiting device 60 generally includes a piston device 66 mounted within cylinder 64 for axial sliding movement within the cylinder for positioning the valve closure element. However, this preferred piston arrangement 66 has a central recess 68. The central recess 68 includes a cylindrical hole 70 having a diameter (D). The diameter of the cylindrical bore 70 is reduced at an opening 72 formed in a first side 74 of the piston arrangement 66 . Opening 72 has a smaller cross-sectional area than cylindrical hole 70.
Actuation rod 76 extends through opening 72 and from first side 74 through a hole 78 in first end 80 of cylinder 64 and, as in prior art valve actuator 10, extends from first side 74 through hole 78 in first end 80 of cylinder 64. It terminates at its extended end which is located on the outside and can be connected to the valve stem. An enlarged piston head 82 is secured at its first side 84 to the other end 86 of the actuating rod 76 and is retained within the cylindrical bore 70 by a portion of the piston device 66 around the opening 72. It is arranged inside the hole 70 as shown in FIG. Piston head 82 includes a seal ring 88 and slides into sealing contact inside bore 70 to limit axial movement within bore 70.

It will be appreciated that in the preferred force limiting device 60, the actuating rod 76 and opening 72 have circular cross-sections, although other cross-sectional shapes may be used without altering the effectiveness of the invention. It will be understood that it can be used reasonably.

Piston device 66 generally includes two elements:
That is, the first piston element 90 includes a central recess 68 and a plurality of bolts 94 to generally surround the cylindrical bore 70.
and a second piston element 92 fixed at zero. each piston element 90, 92;
The piston devices 66 each have a sealing ring 96 to make the piston arrangement 66 generally sealed of the type shown in the prior art valve actuator 10. Actuation rod 76 also includes an axial passageway 98 . The axial passage 98 forms a leakage passage that communicates with the atmosphere through a radially extending passage 100 (more clearly shown in FIG. 3) from the space between the seal rings 96 and the cylindrical bore 70.

The above elements are shown in different angular positions in FIGS. 3 and 4. However, the piston device 66 of this preferred embodiment
0 is shown in different positions in each of FIGS. 2, 3 and 4 to better explain and provide a better understanding. Therefore, in order to gain a better understanding of the forces acting on the piston arrangement 66 and the piston head 82 to enable this preferred embodiment to achieve the objects of the invention, FIGS. and FIG. 4 will be explained separately. As shown in FIG. 2, the valve is still in the closed position and actuating fluid is supplied through access hole 102 into the interior of cylinder 64 to exert an upward force on piston arrangement 66. The magnitude of the force required to lift the valve occlusion element from its valve seat while the actuating rod 76 leaks a designed amount of actuating fluid through the opening 72 and acts on the first side 84 of the piston head 82. is sufficiently large that the required force is actually generated by the working fluid acting on the piston arrangement 66 rather than the working fluid acting on the piston head 82. As a result, the piston head 82 has a cylindrical bore 70 which provides direct contact between the piston head 82 and the first piston element 90.
is placed inside. The resulting large force is transmitted through piston head 82 and actuating rod 76 to open the valve. The force applied to the piston device 66 is derived from the pressure of the working fluid acting on the effective area of the first side 74 of the piston 66.
It should be understood that the effective area of the second side 104 of , minus the pressure of the high pressure gas from the accumulator, is approximately equal to the effective area of the second side 104 of . Similarly, the force exerted on piston head 82 by the working fluid is from the pressure of the working fluid acting on the effective area of first side 84 of piston head 82 to the area of hole 70 on second side 106 of piston head 82. (atmospheric pressure in this preferred embodiment). The resultant force in each case varies depending on the magnitude of the force exerted by the working fluid, with the resultant force acting on the piston arrangement being greater initially while providing the working fluid necessary to open the valve. Therefore, the direct contact between piston device 66 and piston head 82 initially transmits the force necessary to open the valve to the valve stem. However, once the force required to open the initial valve is reduced, as the piston device 66 is moved axially upwardly within the cylinder 64, the pressure of the working fluid is similarly reduced. Under this condition of lower forces on the working fluid, the area and pressure available are such that an initial force is generated in the piston head 82 to displace the valve stem and valve occlusion element. Piston head 82 therefore moves axially within bore 70 to a position as shown in FIG. The magnitude of this force during movement of the valve stem and valve occluding element is equal to the force required to overcome the friction in the seal sealing the valve stem extension through the body, provided the flow pressure differential is relatively low. be approximately equal.

As shown in FIG. 3, the actuating fluid moves the piston device 66 axially within the cylinder 64 toward its second end 108 to place the valve in the back seated position. In this position, just prior to back seating, the actuating fluid still produces a resultant force acting on the piston head 82 and actuating rod 76, which resultant force is greater than the resultant force acting on the piston assembly 66. As a result, the piston head 82 is still located upwardly within the cylindrical bore 70.

As shown in FIG. 4, the pressure of the actuating fluid supplied to the cylinder 64 continues to increase as the upward movement of the actuating rod 76 is restricted by the closure element held opposite the back seat. ensure that the correct force is applied to the valve during back seating. The force applied to piston head 82 and actuating rod 76 is
Similarly, it is determined by the area of the first side 84 of the piston head 82, the area of the second side 106 of the piston head 82, and the respective pressures acting thereon. The increase in pressure of the working fluid also acts on the effective area of the first side 74 of the piston arrangement 66. This force, acting from below the piston head 82, is opposed by the pressure of the high pressure gas acting on the second side 104 of the piston arrangement 66, but creates a significant positive upward pressure on the piston head 82. Piston head 82 continues to be positioned upwardly within cylinder 64 until second side 104 contacts piston stop 110 at second end 108 of cylinder 64.

Although the preferred force limiting device 60 can be utilized with any type of valve regardless of size, this device is suitable for globe and gate valves ranging from 6 inches to 32 inches. It is considered as. However, it is useful to have certain expected parameters for typical valve shapes. For example, for a 16-inch gate valve, the desired force for back seating is 4988.7 Kg (11000 lb) to 544.2
Kg (12000 lbs) range. 40.64cm (16
Typical fluid systems used to operate gate valves (inches) are designed to operate at high pressures up to 4500 pounds per square inch (316 kg/cm ² ). The pressure at this level is 58957Kg
(130,000 pounds) or 63,492Kg (140,000 pounds)
is sufficient to generate an opening force (necessary to lift the gate valve away from the initial valve seat) in the range of forces of . Having a fluid system that can exert this amount of tension on the actuation rod is undesirable for back seating. Such forces are therefore utilized when the elements of the valve actuator are in the position shown in FIG. However, when the valve is back seated as shown in FIG. 66 is held opposite piston stop 110 by a working fluid that generates an upward force acting on piston stop 110 . The actuating fluid in this condition exerts a maximum tension force on the actuating rod 76, creating a pressure on the piston head 82 that is opposed by a predetermined fluid pressure, which in this preferred embodiment is atmospheric pressure.
This maximum tension is significantly less than the force that the hydraulic fluid system can and does apply during initial opening of the valve.

The specific dimensions and areas of the various surfaces described above will have to be determined by the particular requirements of the valve using the valve actuator. Therefore, each force limiting device depends on the anticipated force required to unseat the valve, the force required to back seat the valve, and the force required to quickly close the valve. It would have to be specially designed for the valve.

Therefore, this preferred force control device 60 can be used to limit the tension applied to the actuating rod while in the back seated position, and the device is secured by both sealing rings 96 to the inside of the accumulator 38. It will be appreciated that the leak prevention feature described above prevents leakage of working fluid to 46. To further demonstrate the applicability of the present invention, it is shown that other types of devices for directing working fluid from an external source can be used to properly transmit force to the piston head 82. Should.

As shown in FIG. 5, an alternative valve actuator 120 is used that uses a working fluid and high pressure gas in an accumulator 122 in the manner generally described above. However, the valve actuator 12
0 is a pair of pistons 124 and 126 mounted so as to be able to slide independently inside the cylinder 128.
are using. During normal operation, both pistons are connected to the interior of cylinder 128 when working fluid is supplied to first side 130 of piston 124 and high pressure gas is supplied to first side 132 of piston 126 through access hole 134. move in the axial direction. Access hole 134 extends through a terminal closure device 136 which is secured to the end of cylinder 128.

However, this valve actuator 120 utilizes the actuating fluid to close the valve in the unlikely event that the actuator 122 leaks or ruptures to a level that significantly reduces the pressure of the high pressure gas therein to a level that adversely affects valve closure. Contains structure for closing.

The valve actuator 120 has a tubular housing 13
Contains 8. A tubular housing 138 is secured to the terminal closure member 136 and extends from the closure member to the upper portion of the accumulator 122.
Tubular housing 138 includes an extension end attachment 140 on the outside of accumulator 122 . The terminal attachment 140 is connected to a piping system leading to the atmosphere. Piston 126 includes a hollow tube 142 extending from a first side 132 thereof and housed within an interior portion of tubular housing 138. In the terminal closure member 136, a sealing device 144 is provided between the tubular housing 138 and the hollow tube 142 to enable the hollow tube 142 and the tubular housing 138 to be in sealed sliding contact. Hollow tube 142 is of sufficient length to maintain the contact throughout axial movement of piston 126.

A radially extending groove 146 is formed in at least one of the contact surfaces of the pistons 124,126. Therefore, if high pressure gas is not available to close the valve, working fluid can be supplied to the tubular housing 138 through the extended end 140. The working fluid acts on the upper surface of the piston 124 through the hollow interior portion of the hollow tube 142 . When the working fluid is supplied between the piston 124 and the piston 126, the piston 126 closes the end closure member 13.
6 and the piston 124 is moved downward to close the valve.

The above description shows how actuator 120 can be used to close a valve in the absence of high pressure gas and when the actuating rod is rigidly fixed to piston 124 in a manner that does not utilize the principles of the present invention. be understood.

However, as shown in FIG.
Contains 2. A piston head 154 is sealably and slidably disposed within a cylindrical bore 156 of piston 124. cylindrical hole 1
56 is narrowed at an opening 158 in the first side 130 of the piston 124. During normal operation, the piping associated with the end fitting 140 is open to the atmosphere and therefore the piston 124,
The space between the seal ring associated with piston head 126 is vented to leak the working fluid so that atmospheric pressure
60. The relative position of the piston head 154 within the cylindrical bore 156 is such that the piston 124,
126 is the same as in the embodiments shown in FIGS. 2 to 4.

If high pressure gas is not available for actuator 120, the valve closes the vent associated with attachment 140 and closes tubular housing 13.
8 could be closed by introducing working fluid. Supplying actuating fluid between piston 124 and piston 126 causes piston 124 to move axially to close the valve. The actuating fluid applies sufficient force to the piston to position the piston 124 downwardly relative to the piston head 154, thereby contacting the stopper collar 170, which is threadedly mounted within the bore 156, against the piston head 154 and closing the valve. It acts on the head 154 and the actuating rod 152.

Although two embodiments of the present invention have been shown above that can be combined with valve actuators of the type that use working fluid and high pressure gas, it is understood that the force limiting device of the present invention can be appropriately attached to other types of actuators. Should be a finger drop.
For example, if the valve actuator is of the type that simply uses a hydraulic cylinder and selectively supplies actuating fluid to opposite sides of a piston member slidably mounted therein, The force limiting device of the present invention can likewise be utilized to limit the tension force exerted on the actuating rod during operation. Even though the actuating fluid can be introduced on both sides of the piston, to control the amount of tension acting on the actuating rod when the piston is firmly positioned relative to the cylinder and stopper in the direction of opening the valve. A central recess may be provided which can communicate with the atmosphere.

Although in the preferred embodiment of the invention the fluid pressure source applied to the piston head was air at atmospheric pressure, the same results may be achieved using any other device that utilizes a gas or fluid at a given pressure. The gains are clear. It will be obvious that modifications and variations may be made within the scope of the invention as claimed and as described in the preferred embodiments of the invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a prior art valve actuator including a coupling between the actuating rod and the valve stem, with the valve shown in a back seated position; FIG. 2 shows various features of the present invention; Figure 3 is a partially cut-away side view in cross-section of a preferred force limiting device having a valve opening, showing the position of elements when the valve is open; FIG. 4 is a partially cut-away side view showing a cross-section of the embodiment of FIG. 2 in a position just before back seating when completely absent; FIG. 4 is a partial cross-sectional view of the embodiment of FIG. FIG. 5 is a cutaway side view and a cross-sectional side view of another embodiment of the invention, with elements shown in position for back seating; FIG. 10...Valve actuator, 12...Fluid pressure cylinder, 14...Yoke, 16...Valve, 18...
Piston, 20... Operating rod, 22... Piston 1
8, 24...opening, 26...first end of cylinder 12, 28...extension end, 30...
Coupling device, 32... valve stem, 34... bonnet, 36... closing member, 38... accumulator, 40... pressure wall, 42... opening, 44...
...Second end of cylinder 12, 46...Inner side of accumulator, 48...Second side of piston 18, 50...Inlet/outlet hole, 52...Seal ring,
54... Passage, 56... Passage, 58... Attachment member, 60... Force limiting device, 62... Valve actuator, 64... Cylinder, 66... Piston device, 68... Central recess, 70... cylindrical hole,
72... opening, 74... first side of piston device 66, 76... actuating rod, 78... hole, 80...
First end of cylinder 64, 82... Piston head, 84... First side, 86... Other end of actuating rod 76, 88... Seal ring, 90... First
Piston element, 92...Second piston element, 94
... Bolt, 96 ... Seal ring, 98 ... Passage, 100 ... Passage, 102 ... Entry/exit hole, 10
4... Second side of piston device 66, 106...
second side of piston head 82, 108... second end of cylinder 64, 110... piston stopper, 120... valve actuator, 122...
Accumulator, 124, 126...Piston,
128...Cylinder, 130...Piston 124
132... First side of the piston 126, 134... Access hole, 136... Terminal closure device, 138... Tubular housing, 140... Terminal attachment member, 142... Hollow tube , 144... Sealing device, 146... Groove, 150... Pressure limiting device, 152... Actuation rod, 154... Piston head, 156... Hole, 158... Opening, 158...
. . . opening, 160 . . . upper side of piston head 154.

Claims (1)

[Scope of Claims] 1. Fluid from a second source is supplied to a second source of a piston device.
from a first source selectively supplied to and discharged from the cylinder on a first side of a piston arrangement mounted inside the cylinder and connected to the working rod when acting in opposite directions on the sides; In a device for limiting the force acting on the actuating rod of a type of valve actuator containing a working fluid,
The piston device has a central recess that includes a cylindrical hole, the cylindrical hole having a diameter that decreases at an opening formed in the first side of the piston device, such that the opening is the actuating rod has a smaller cross-sectional area than the cylindrical hole, and the actuating rod extends from the first side of the piston device through the hole in the first end of the cylinder and is located outside the cylinder and is connected to the valve. slidably received within said opening terminating in an extended end connectable to a rod, secured to the other end of said actuating rod at a first side and around said opening; an enlarged piston head disposed within the cylindrical bore so as to be retained by a portion of the piston arrangement, the piston head having limited axial movement within the cylindrical bore; a predetermined supply from a third source different from the first source and the second source in sliding and sealing contact with the interior of the cylindrical hole and in communication with the cylindrical hole so as to means for applying a fluid pressure to a second side of the piston head, the actuating fluid being held by the piston device against a piston stop at the second end of the cylinder. generating a pressure on the piston head opposite to the predetermined fluid pressure to exert a maximum tension on the actuating rod when the actuating rod is in the actuating position, thereby creating a force on the piston device greater than the maximum tension; A device for limiting the force acting on the actuating rod of a valve actuator, characterized in that: 2. A device for limiting the force acting on an actuating rod of a valve actuator as claimed in claim 1, wherein the fluid from the second source includes high pressure gas in an accumulator attached to the cylinder, and An apparatus for limiting the force acting on an actuating rod of a valve actuator, wherein the predetermined fluid pressure from the third source includes atmospheric pressure of air from an air vent communicating with the atmosphere. 3. A device for limiting the force acting on an actuating rod of a valve actuator according to claim 1, wherein the piston device has the cylindrical bore, the opening, and a first side of the piston device. a first piston element and a second piston element of the piston device;
a second piston element including a side portion;
At the side, the second piston element is connected to the first piston element.
disposed on the piston element to define an end of the recess remote from the first side of the piston arrangement to capture the piston head within the cylindrical bore; A device that limits the force acting on the actuating rod of a valve actuator. 4. The device for limiting the force acting on the operating rod of a valve actuator according to claim 3, characterized in that the first piston element and the second piston element are fixed to each other. A device that limits the force acting on the actuator's operating rod.