JPH0434035B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a remotely controllable actuator for a flow control valve or similar valve, particularly for controlling such a valve to control a desired flow in the event of failure or loss of actuator control power. The invention relates to a fail-safe gate valve having an actuator actuated to move it into a controlled state.

BACKGROUND OF THE INVENTION Remotely operable actuators for flow control valves are well known in the fluid distribution and control art. Such valves and actuators are recommended for use in harsh environments, for use in automatic flow distribution systems, and for use in environments where operators generally cannot manually change the flow control state of the valve. The combination with is very useful.

A first flow control state and a second flow control state, such as a gate valve operated between a fully open position and a fully closed position.
Control valves that operate between flow control states use a controllable source of pressurized hydraulic fluid as the control force to push or pull the stem of a stem-lifting gate valve with an actuator. Normally, this valve is opened and closed by Forms using pressurized hydraulic fluid include a hydraulic piston coaxial with the ascending valve stem and driving the stem either inwardly or outwardly depending on the supply of sufficient hydraulic control fluid pressure. There is something to do. This arrangement typically also includes a return spring that drives the valve stem in the opposite direction upon release or failure of the pressurized control fluid source.

Referred to as "fail-safe" valves due to their ability to return the valve's fluid flow control state to a known state when adequate control fluid pressure is not present, this type of valve is designed to prevent damage to the control system or equipment. It is particularly suitable for oil or gas production applications where it is imperative to know the status of the flow system with certainty during failures. For example, the above-described fail-safe valve may be installed in the main flow line of a remote gas or oil production distribution facility such that the valve remains driven open by a hydraulic control fluid at sufficient pressure. When the system is operating normally, the main gas or oil line remains open, and other downstream valve and actuator assemblies direct and distribute the flow. It's on. In the unlikely event of a control system failure and loss of control fluid pressure, the gas and/or oil main line control valves are biased to the closed position by return springs, cutting off all flow to the downstream distribution system. to prevent overpressure, overflow, equipment damage, or other undesirable consequences.

A conventional valve-actuator combination of this type is the one by Atsukerman and Vaszkes.
In UK application GB 2115 111 dated 1 September 1983,
It is disclosed in U.S. Pat. These patents show a valve actuator that raises or lowers the stem of a stem-rising gate valve in response to sufficient control fluid pressure, and that the valve actuator raises or lowers the stem of a stem-rising gate valve in response to sufficient control fluid pressure, and that It includes spring means for driving the valve stem in the opposite direction when closed.

As those skilled in the art will appreciate, it is desirable for such applications where the ability of the valve to automatically switch to a "fault" flow control state upon loss of pressure in the control system is important. Immediately following the loss of , the return spring quickly moves the valve stem to the return position. This return movement is inhibited by the inertia of the moving elements of the valve and actuator and by "sticking" or other mechanical drag due to sliding sealing surfaces. For hydraulically operated valves using liquid control fluid, especially those located at a considerable distance from the source of the control fluid,
The fluid resistance resulting from having to displace the hydraulic control fluid from the actuator piston and back to the source through the control fluid supply line is quite significant, allowing the actuator to control the valve to the desired flow control state. It is understood that the time required to move it is quite long. It will also be appreciated that this mechanical resistance is at its maximum value at the moment of failure when the control fluid and actuator elements are still at rest. If this inertial resistance is overcome and the control fluid begins to flow out of the valve actuator, a "failure" occurs.
A force much less than the initial force is sufficient to continue movement of the valve stem into position.

Additionally, as is common practice in some applications, control wires are routed through the flow conduits and open valves of various equipment to monitor the equipment and retrieve information. In such a case, emergency closing of the valve gate due to failure or other reasons must be performed to disconnect the control wires in use at the time. Therefore, for these valves that are closed by a resilient force, it is imperative that the spring force be strong enough to not only drive the gate member into the closed position, but also to sever the control wire. That's true.

Prior art actuators use coil springs of such strength that, when fully deflected, they produce a force sufficient to overcome the combined inertia of the control fluid and actuator. I'm making it a thing. However, once the valve stem moves under the force of this type of spring, the constant elastic force characteristic of the coil spring results in an unnecessarily large driving force being applied to the valve stem. Also, in the case of a valve actuator that uses a very strong coil spring to overcome such a large initial resistance, the actuator becomes quite large and unwieldy.

Further requirements for this type of actuator are that it be simple in design, compact, quickly and easily disassembled, accessible for maintenance, and capable of overcoming the initial inertial resistance of the control fluid in the fluid supply line. It is possible.

SUMMARY OF THE INVENTION The present invention includes a valve body, a bonnet, an elongated valve stem, a gate member, and a valve stem driving means, the valve body having a flow path for allowing a fluid to flow, and one end of a cavity in the valve body. The bonnet is open to the flow path and reaches the surface of the valve body at the other end, the bonnet is sealingly attached to the valve body at the other end of the cavity, and the bonnet is connected to the cavity at one end. a central bore opening into the cavity, the valve stem being disposed within the central bore and reciprocating axially therethrough in first and second directions; The gate member has an outer end that terminates outside the valve body and the bonnet, and an inner end of the gate member that engages the valve stem and reciprocates therewith to cross the flow path. the valve stem drive means is arranged to move the valve stem in a first direction axially in response to the presence of a control force to control flow in response to reciprocating axial movement of the valve stem; In the fail-safe gate valve, a bamboo spring is arranged around the valve stem, and the first
axially compressing the valve stem in response to axial movement of the valve stem in a second direction and driving the valve stem axially in a second direction when the control force is removed. It's on the gate valve.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is a diagram illustrating a valve stem ascending type gate valve (gate valve) and its actuator, which is a first embodiment of the present invention. This gate valve includes a valve body 33 having a flow path 82. The gate member 35 reciprocates transversely to the flow path 82 between a lowered open position (left half in FIG. 1) and a raised closed position (right half in FIG. 1). In addition, the flow path 8
A valve seat member 34 is arranged around the valve 2 at the point of contact with the gate member 35 to seal the space therebetween.

Bonnet 1 is attached to valve body 33 by bolts 30 or other known fastening means. The bonnet 1 and the valve body 33 form a valve cavity 84 communicating with the flow path 82, and the gate member 35 reciprocates between the raised position and the lowered position as described above.
is accepted. The space between the bonnet 1 and the valve body 33 is sealed with a bonnet seal ring 32.

The valve stem 9 is cooperatively engaged with the gate member 35 and extends outwardly from the valve cavity 84 through a hole 86 in the bonnet 1. Packing 3
1 surrounds the valve stem 9 to form a fluid-tight seal between the valve stem 9 and the bonnet 1, and also allows the valve stem 9 to reciprocate as shown in FIG. The packing holding nut 2 is threadedly engaged with the bonnet 1 to compress and hold the packing 31 during normal operation.

The actuator according to the invention will be described in more detail below with reference to the illustrated housing 8 which is attached to the bonnet 1 by the cooperation of the locking ring 3, the bonnet adapter 4 and the base plate 5. To assemble this actuator, the bonnet adapter 4 is dropped downward past the bonnet 1 and the lock ring 3 disposed around the bonnet 1. Next, the base plate 5 and the housing 8 are placed in the posture shown in FIG. 1, and the bonnet adapter 4 is lifted outward as shown in FIG. 1 to be screwed into the housing 8, and the bonnet adapter 4 is rotated. By doing so, it is tightened firmly.

Although the actuator according to the invention can be mounted to such a valve by various mounting means known in the art, more specifically to the valve bonnet 1, the mounting structure illustrated in FIG. 1 and described above does not require complete disassembly of the actuator. The advantage is that the bolts 30 securing the bonnet to the valve can be accessed without having to be removed. This is Bonnet Adapter 4
This can be done by loosening the screws from the housing 8, removing it downward, and sliding it around the bonnet 1. In this way, the bonnet holding bolt 30 can be tightened or loosened with a wrench.

Continuing with the description of the actuator according to the invention, the piston 17 is arranged coaxially with the axis 88 of the valve stem 9 and axially outward from the valve stem. This piston 17 is attached to the housing 8 by a retaining nut 16. The retaining nut 16 does not permit axial translation or rotation of the piston 17. Piston 17 is actually a cylindrical member closed at its outer end by an end cap 20, as shown in FIG.

A cylinder 15 is slidably fitted around the piston 17. The inner end of the cylinder 15 is fixed to the outer end of the valve stem 9 by a hexagonal nut 12. An annular piston seal ring 11 provides a fluid-tight seal between the cylinder 15 and the piston 17. Piston 17, end cap 20, and cylinder 15 define a control volume 90 that expands and contracts by the telescoping action of cylinder 15 and piston 17.

For the operation of the actuator, the supply pipe 9
Pressurized hydraulic fluid or gas is supplied to the control volume portion 90 via 2 . As is apparent from FIG. 1 and the above description, pressurized hydraulic fluid or gas entering control volume portion 90 drives cylinder 15, thereby driving valve stem 9 and gate member 35 axially inwardly. be done. As a result, the valve is opened, as shown in FIG. 1, allowing free flow through channel 82.

The actuator according to the invention is also provided with spring means 7 for forcing the cylinder 15 axially outwards when the hydraulic pressure in the control volume 90 is removed. According to the invention, this spring means 7 is a bamboo spring. This has a plurality of blades 7a, 7b, 7c of rectangular cross section as shown in FIG.
Cylinder 15, bonnet 1 and base plate 5
It is compressed between

This bamboo shoot spring 7 has a variable characteristic in which the deflection rate decreases as the compression increases, and the deflection rate becomes minimum when it is fully compressed, as shown in the left half of FIG. It is particularly advantageous for applications such as those mentioned above. In detail, the blades 7a, 7b, 7c combine as the bamboo shoot spring is compressed, and when fully compressed, they densely occupy space within the housing 8, forming a coil spring with the same modulus of elasticity. In comparison, the height of the vertical section is very low. The action of the bamboo shoot spring 7 used in the present invention is shown in Fig. 3a, which shows the relationship between the compression force and axial displacement of a standard coil spring, and Fig. 3a, which shows the relationship between the compression force and axial displacement of the bamboo shoot spring. This is clear when compared with FIG. 3b. That is, the force required to compress the bamboo shoot spring increases rapidly as the compression limit or bottom point 94 is approached. In standard coil springs, the force vs. distance relationship is linear until the individual coil tires (ie, bottoms out).

The bamboo spring blades 7a, 7b, 7c can have various cross-sectional shapes, such as circular, rectangular, and trapezoidal. The shape and dimensions of the blades can be varied over the length of the spring, allowing the modulus of elasticity to be tailored to a given application. The rectangular shape shown in FIG. 1 is relatively easy to manufacture, has the advantage of lateral stability, and can be relatively easily shaped and cut.

When the hydraulic pressure holding the valve stem 9 and the gate part 35 in the inward position (left half of FIG. 1), which is the first flow control state, is released, the bamboo shoot spring 7 applies its maximum force to the cylinder 15. Acting outward, compressing control volume portion 90 forces hydraulic control fluid or gas back into supply line 92 . As already explained, the internal resistance to this movement is greatest at its initiation and decreases as the backflow of fluid and movement of the cylinder begins. See Figure 3b. The bamboo spring 7 according to the invention provides maximum force when it is most needed, and this force decreases as the valve stem moves axially outward towards the second flow control condition.

The embodiment of FIG. 1 shows means for indicating the position of gate member 35. This is indicator alignment ring 1 attached to cylinder 15.
3 and reciprocates together with the horizontal pointing rod 27. This horizontal indicator rod 27 protrudes from inside the indicator guide plate 25,
It is visible through a transparent lens 26 attached to the housing 8 by socket screws 24.
FIG. 2 shows the position indicating means shown in FIG. 1, with the horizontal indicator rod 27 in the valve open position shown in solid lines and the horizontal indicator rod 27 in the valve closed position shown in broken lines.
Such a position indicating means allows the condition of the gate valve to be quickly checked from the outside from a remote location, making it unnecessary to check the condition of the gate valve closely.

FIG. 4 shows a combination of a second embodiment of the actuator of the present invention and a gate valve. In this example, during disassembly for maintenance or other purposes,
It includes means for retaining the bamboo shoot spring 7 within the housing 8'. The combination of the gate valve and actuator shown in FIG. 4 is basically the same as that shown in FIG. 1, so the same members are designated with the same reference numerals. Also, members having the same functions as the corresponding members in FIG. 1, although somewhat different in form, are indicated by dashes and the same reference numerals. For example, housing 8' corresponds to housing 8 in FIG. 1, and cylinder 15' in FIG. 4 corresponds to cylinder 1 in FIG.
It corresponds to 5. The valve stem position indicating means shown in FIG. 1 is not shown in FIG. 4 for simplicity.

FIG. 4 shows in detail the means for preloading and retaining the bamboo spring 7 within the housing 8' during disassembly of the gate valve and actuator assembly. The lower end of the housing 8' includes an annular locking groove 93. This locking groove 93 is open radially inward to receive a plate retaining spring ring 95. A plate retaining spring ring 95 extends radially into the housing 8';
engaging the base plate 5 within the housing 8';
This is locked.

The upper end of the housing 8' includes a shoulder portion 98 that projects radially into the housing. Cylinder 15' includes an annular shoulder 100 that engages an upper spring retaining ring 102. The upper spring retaining ring 102 contacts the blade 7c at the innermost side of the bamboo shoot spring 7 and transfers the elastic force directed outward to the cylinder 1.
5' to the annular shoulder 100 and thus cylinder 1
5'.

During disassembly of the actuator, the action of plate retaining spring ring 95, spring retaining ring 102, shoulder portion 98, annular shoulder 100 and locking groove 93 capturing the bamboo shoot spring is apparent. That is, first, the holding nut 16 is loosened and the piston 17 is pulled out from the actuator to begin disassembly.
Once the piston 17 is removed, the cylinder 15' is removed by removing the hexagonal nut 12 from the valve stem 9. This cylinder 15' is slid out of the housing 8' along the axial direction and pulled out. Next, remove the packing retaining nut 2 and remove the packing 31 of the valve stem.

Reference is now made to the right half of FIG. 4 showing the closed gate valve and actuator assembly. Upper spring retaining ring 102 extends radially outwardly and engages shoulder portion 98 of housing 8', preventing further extension of bamboo spring 7. Removal of the actuator is completed by removing the housing retaining screw 96 and lifting off the housing 8' holding the bamboo shoot spring 7 therein. Reassembly of the actuator can be accomplished by reversing the operations described above.

An advantage of the embodiment of FIG. 4 is that parts of the actuator can be removed or replaced without releasing or precompressing the bamboo spring. If a wire line (not shown) disposed within the channel 82 must be cut, a very strong bamboo spring 7 is used to provide sufficient force for the gate portion 35 to cut the wire line. By necessity, the bamboo shoot spring must be highly precompressed, which has traditionally made on-site assembly difficult and expensive.

According to the embodiment of FIG. 4, by confining the pre-compressed bamboo shoot spring 7 within the housing 8', field workers do not need special equipment or tools to compress the bamboo shoot spring 7. without any
The actuator can be disassembled and reassembled. The housing retaining screw 96 has a first
It can be compared with the other means shown in the figure in terms of simplicity and ease of use, and is functionally equivalent.

The accompanying drawings and written description reflect what is considered to be the best mode embodiment of the invention. Accordingly, what is disclosed herein should be understood as such and not limited thereto. Although the invention has been described in relation to a gate valve, an actuator according to the invention
It is equally useful in other types of valves having rising stems or using linearly reciprocating actuating members. Similarly, the gate valves described above are of the type that open fully when the stem is fully inserted and close the flow when the stem is pulled outward.
The actuator of the present invention may be combined with a gate valve that operates in the opposite manner. In that case, the valve would "fail open" upon loss of control pressure and could be used to release firefighting fluid or safely vent a pressure tank.

Additionally, although a hydraulic piston has been described that responds to pressure, i.e., the absence of a pressurized control fluid or gas, actuators according to the present invention may have an inward or outward force in response to the presence or absence of a control force. Any suitable means for forcing the valve stem 9 in either direction may be used, including, for example, electrical, magnetic, thermal response, gravimetric response, and the like. Furthermore, the control forces described above need not necessarily be generated from a source controlled by an operator or a computer, such as hydraulic or air pressure in the flow path 82, electrical current, the attitude of the actuator relative to the gravity vector, fluid or gas. It may depend on any physical phenomenon or property that generally exerts a force on the drive means, such as the viscosity or velocity of the drive means. These configurations will be apparent to those skilled in the art from the description herein.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a combination of a gate valve and an embodiment of an actuator according to the invention. FIG. 2 is a front view of the position indicating means shown in FIG. 1. Figure 3a is a graph of force versus displacement for a standard coil spring. FIG. 3b is a graph showing force versus displacement for bamboo shoot springs. FIG. 4 is a longitudinal sectional view of another embodiment of the actuator having means for retaining the bamboo shoot spring in a pre-compressed state within the housing. DESCRIPTION OF SYMBOLS 1... Bonnet, 2... Packing retaining nut, 3... Lock ring, 4... Bonnet adapter, 5... Base plate, 7... Spring means or bamboo shoot spring, 8... Housing, 9... Valve stem, 11 ... Piston seal ring, 12 ... Hexagonal nut, 13 ... Indicator alignment ring, 15 ... Cylinder, 16 ... Holding nut,
17... Piston, 20... End cap, 24...
...Socket screw, 25 ... Indicator guide plate, 26 ... Transparent lens, 27 ... Horizontal indicator rod, 30 ... Bolt, 31 ... Packing,
33... Valve body, 34... Valve seat member, 35... Gate member, 82... Channel, 84... Valve cavity,
86... Hole, 88... Valve stem axis, 90... Control volume portion, 92... Supply pipeline, 93... Locking groove, 94... Compression limit or bottom point, 95... Plate retaining spring ring, 96... Housing holding screw, 98... Shoulder portion, 100... Annular shoulder, 10
2... Spring retaining ring.

Claims (1)

[Scope of Claims] 1. A valve body comprising a valve body, a bonnet, an elongated valve stem, a gate member, and a valve stem driving means, the valve body having a flow path through which a fluid flows, and one end of a cavity in the valve body. The bonnet is open to the flow path and reaches the surface of the valve body at the other end, the bonnet is sealingly attached to the valve body at the other end of the cavity, and the bonnet is connected to the cavity at one end. a central bore opening into the cavity, the valve stem being disposed within the central bore and reciprocating axially therethrough in first and second directions; The gate member has an outer end that terminates outside the valve body and the bonnet, and an inner end of the gate member that engages the valve stem and reciprocates therewith to cross the flow path. the valve stem drive means is arranged to move the valve stem in a first direction axially in response to the presence of a control force to control flow in response to reciprocating axial movement of the valve stem; In a fail-safe gate valve adapted to be actuated, a bamboo spring is disposed about the valve stem and is axially compressed in response to axial movement of the valve stem in a first direction to provide a control force. A fail-safe gate valve characterized in that when removed, the valve stem is axially driven in a second direction. 2. A valve according to claim 1, wherein the bamboo spring has turns of essentially rectangular cross section. 3. A fail-safe gate valve according to claim 1, wherein the control force is derived from a source of pressurized liquid or gas. 4. The means for driving the valve stem axially inward,
a hollow cylinder, a cylindrical hollow piston oriented in line with the cylinder, and a housing, the cylinder having a first closed end secured to an axially outer end of the valve stem; , the cylinder extends axially outwardly from the valve stem and has a second open end, and the piston extends axially outwardly from the valve stem and has a second open end.
the housing is closed at an outer end thereof and open at a second inner end and is received for sealing and axial movement within the cylinder to define a control space within the cylinder; Claims: 1. A housing fixed to a bonnet and surrounding said valve stem, cylinder, piston and bamboo spring; and further characterized in that said housing is fixed and supported to said piston so as to be immovable relative to said bonnet. The fail-safe gate valve according to paragraph 3. 5. The fail-safe gate valve according to claim 4, wherein the bonnet is sealingly attached to the valve body by a plurality of bonnet retaining nuts arranged around the center hole, a removable lock ring that engages the periphery and extends radially outwardly from the bonnet; and a removable lock ring that abuts the valve body side of the lock ring and is threaded onto the housing to removably fix the housing to the bonnet; and a bonnet adapter ring that prevents relative movement at the
A fail-safe gate valve in which the bonnet adapter ring is moved toward the valve body when removed from the housing to provide free access to the bonnet retaining nut. 6 comprising means for retaining said bamboo shoot spring within said housing in a pre-compressed state when said housing is removed from said bonnet, said bamboo shoot spring being pre-compressed prior to axial movement of said valve stem in a first direction; Claim No. 4
Fail-safe gate valve as described in section. 7. The bamboo shoot spring retaining means is arranged in the housing and opens radially inwardly and is disposed axially inwardly with respect to the bamboo shoot spring, and engages with the locking groove and holds the locking groove therein. 7. A fail-safe gate valve according to claim 6, including a plate retaining spring extending radially inwardly from said bamboo spring to prevent axial inward movement of said bamboo spring. 8. The bamboo shoot spring retaining means further includes an annular shoulder located at an axially outer end of the housing and extending inwardly therefrom to prevent axial outward movement of the bamboo shoot spring. The fail-safe gate valve according to item 7. 9. Claims further comprising an annular base plate disposed around the valve stem between the bamboo shoot spring and the plate retaining spring to transmit an axial force therebetween. The fail-safe gate valve according to clause 8. 10 further including an annular upper spring retaining ring, the spring retaining ring contacting the axially outer end of the bamboo spring and extending radially outwardly from the reciprocating cylinder; said cylinder annular shoulder and said spring retaining ring are in constant engagement with said cylinder annular shoulder and said spring retaining ring cooperate to prevent relative axial outward movement of said spring retaining ring beyond said cylinder annular shoulder; and wherein the spring retaining ring has a radial dimension to engage a shoulder portion of the housing to prevent axial outward movement of the bamboo spring. Fail-safe gate valve as described in section.