U.S. patent application number 11/301785 was filed with the patent office on 2006-05-04 for valve actuator apparatus.
This patent application is currently assigned to Safoco, Inc.. Invention is credited to Terry G. Young.
Application Number | 20060091339 11/301785 |
Document ID | / |
Family ID | 22766316 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060091339 |
Kind Code |
A1 |
Young; Terry G. |
May 4, 2006 |
Valve actuator apparatus
Abstract
A valve actuator apparatus and method comprises an operator
housing secured to a bonnet assembly. The bonnet assembly is
secured to the valve body, and includes a bonnet stem movably
within a bonnet housing for moving a gate within the valve body to
open and close the valve. A downstop member is fixably secured to
the bonnet stem and engages removable stem spacers which are added
or removed to obtain a selected bonnet stem drift setting. The
operator housing connects to a base ring that surrounds the bonnet
housing and rotates to allow positioning of a fluid port in the
operator housing. The operator housing may removed and replaced
without altering the bonnet stem drift adjustment. A top shaft
extends from the operator housing and rotates with respect to the
bonnet stem to prevent torque transmission from the top shaft to
the bonnet stem. A replaceable sealing cartridge sealingly supports
the top shaft for axial movement within the operator housing.
Inventors: |
Young; Terry G.; (Spring,
TX) |
Correspondence
Address: |
Patterson & Sheridan
Suite 1500
3040 Post Oak Blvd.
Houston
TX
77056
US
|
Assignee: |
Safoco, Inc.
|
Family ID: |
22766316 |
Appl. No.: |
11/301785 |
Filed: |
December 13, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10988957 |
Nov 15, 2004 |
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11301785 |
Dec 13, 2005 |
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10244376 |
Sep 16, 2002 |
6854704 |
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10988957 |
Nov 15, 2004 |
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09888194 |
Jun 23, 2001 |
6450477 |
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10244376 |
Sep 16, 2002 |
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09538881 |
Mar 30, 2000 |
6250605 |
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09888194 |
Jun 23, 2001 |
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08968904 |
Nov 6, 1997 |
6089531 |
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09538881 |
Mar 30, 2000 |
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08206424 |
Mar 4, 1994 |
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08968904 |
Nov 6, 1997 |
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Current U.S.
Class: |
251/14 |
Current CPC
Class: |
F16K 31/145 20130101;
F16K 31/1268 20130101; F16K 31/1262 20130101; F16K 41/04
20130101 |
Class at
Publication: |
251/014 |
International
Class: |
F16K 31/12 20060101
F16K031/12 |
Claims
1. A valve actuator for moving a valve gate between open and closed
valve positions within a valve body upon movement in first and
second directions of a bonnet stem secured to the valve gate, the
valve actuator comprising: an operator assembly comprising: an
operator housing; and an operator member within the operator
housing, wherein the operator member is drivable in the first
direction in response to fluid pressure applied to the operator
member; and a bonnet assembly comprising: a contact member with a
first end configured to form a connection to the bonnet stem,
wherein at the connection the first end of the contact member has a
larger outer diameter than the bonnet stem, and wherein the contact
member has a second end defining a surface configured to receive a
drive force in the first direction from the operator member for
moving the bonnet stem in the first direction; a spring for
producing a biasing force in the second direction opposite the
first direction; a spring retainer with an inner flange for
engagement with an outer flange of the contact member, wherein the
spring imparts the biasing force to the spring retainer that
transmits the biasing force to the bonnet stem via the contact
member for moving the bonnet stem in the second direction; wherein
the operator and bonnet assemblies are held together by attachment
of the bonnet assembly to the operator housing while the operator
member and the bonnet assembly are not held together within the
operator housing, but form an abutting relationship with one
another.
2. The actuator of claim 1, wherein the operator assembly further
comprises a shaft that is coaxial with the bonnet stem, extends
from a shaft aperture in the operator housing and forms an abutting
relationship with the bonnet assembly without the shaft and bonnet
assembly being held together within the operator housing.
3. The actuator of claim 1, wherein the contact member includes an
internally threaded bore adapted to receive an external threaded
surface of the bonnet stem to provide the connection.
4. The actuator of claim 1, further comprising: a seal assembly
disposed within a shaft aperture of the operator housing, the seal
assembly sealing an annulus between an inside diameter of the shaft
aperture and an outside surface of a shaft coaxial with the bonnet
stem and extending through the shaft aperture; and a retainer ring
disposed within the shaft aperture above the seal assembly for
retaining the seal assembly within the shaft aperture, the retainer
ring accessible from the exterior of the actuator to permit removal
of the retainer ring and seal assembly without removing the
operator assembly from the bonnet assembly.
5. The actuator of claim 1, further comprising: a flexible
diaphragm covering a portion of the operator member and isolating a
chamber within the operator housing; and a diaphragm retainer
having external threads threaded to a central internally threaded
aperture of the operator member, wherein the diaphragm retainer
provides a circular groove disposed therein for receiving a seal
that engages the flexible diaphragm sandwiched between the operator
member and the diaphragm retainer.
6. The actuator of claim 1, wherein the contact member defines a
downstop surface that limits travel of the contact member due to
engagement with a stop surface fixed relative to the valve
body.
7. A valve actuator for moving a valve gate between open and closed
valve positions within a valve body upon movement in first and
second directions of a bonnet stem secured to the valve gate, the
valve actuator comprising: an operator assembly comprising: an
operator housing; and an operator member within the operator
housing, wherein the operator member is drivable in the first
direction in response to fluid pressure applied to the operator
member; and a bonnet assembly comprising: a contact member with an
internal threaded bore engaged with an external threaded end of the
bonnet stem, wherein the contact member defines a drive surface
configured to receive a drive force in the first direction from the
operator member for moving the bonnet stem in the first direction;
a spring for producing a biasing force in the second direction
opposite the first direction; a spring retainer with an inner
flange for engagement with an outer flange of the contact member,
wherein the spring imparts the biasing force to the spring retainer
that transmits the biasing force to the bonnet stem via the contact
member for moving the bonnet stem in the second direction; wherein
the operator and bonnet assemblies are held together by attachment
of the bonnet assembly to the operator housing while the operator
member and the bonnet assembly are not held together within the
operator housing, but form an abutting relationship with one
another.
8. The actuator of claim 7, wherein the operator assembly further
comprises a shaft that is coaxial with the bonnet stem, extends
from a shaft aperture in the operator housing and forms an abutting
relationship with the bonnet assembly without the shaft and bonnet
assembly being held together within the operator housing.
9. The actuator of claim 7, further comprising: a seal assembly
disposed within a shaft aperture of the operator housing, the seal
assembly sealing an annulus between an inside diameter of the shaft
aperture and an outside surface of a shaft coaxial with the bonnet
stem and extending through the shaft aperture; and a retainer ring
disposed within the shaft aperture above the seal assembly for
retaining the seal assembly within the shaft aperture, the retainer
ring accessible from the exterior of the actuator to permit removal
of the retainer ring and seal assembly without removing the
operator assembly from the bonnet assembly.
10. The actuator of claim 7, further comprising: a flexible
diaphragm covering a portion of the operator member and isolating a
chamber within the operator housing; and a diaphragm retainer
having external threads threaded to a central internally threaded
aperture of the operator member, wherein the diaphragm retainer
provides a circular groove disposed therein for receiving a seal
that engages the flexible diaphragm sandwiched between the operator
member and the diaphragm retainer.
11. The actuator of claim 7, wherein the contact member defines a
downstop surface distal from the drive surface to limit travel of
the contact member due to engagement of the downstop surface with a
stop fixed relative to the valve body.
12. The actuator of claim 7, wherein the contact member includes a
formation protruding from a center region thereof, which is coaxial
with the bonnet stem and surrounded by the drive surface.
13. The actuator of claim 12, wherein the formation is configured
for engagement by a tool capable of rotating the contact member to
tighten the contact member onto the bonnet stem.
14. A valve actuator for moving a valve gate between open and
closed valve positions within a valve body, the valve actuator
comprising: an operator assembly comprising: an operator housing
defining a pressure chamber therein and having a fluid entry port;
and an operator member within the operator housing movable toward
the valve body in response to pressurized fluid introduced into the
operator housing pressure chamber through the fluid entry port; and
a bonnet assembly comprising: a bonnet housing securable to the
valve body, the bonnet housing having a bonnet housing bore
therethrough; an elongated bonnet stem having first and second
ends, the stem axially movable in the bonnet housing bore, and
securable at the second end to the valve gate for moving the valve
gate to the open and closed valve positions; a spring for producing
a biasing force opposing axial movement of the operator member
toward the valve body; a contact member, separate from the operator
member, having an outer flange, and rotatably and axially affixed
to an outside diameter of the first end of the bonnet stem, and
having a surface facing the operator member for drive contact with
the operator member; an upper spring retainer having an inner
flange for engagement with the outer flange to transmit the biasing
force to the bonnet stem and to receive the movement of the
operator member toward the valve body; and a base ring coupled to
and coaxially surrounding the bonnet housing, wherein at least one
fastener secures the operator housing to the base ring while the
operator member and the bonnet assembly are not held together
within the operator housing, but form an abutting relationship with
one another.
15. The actuator of claim 14, wherein the operator assembly further
comprises a shaft that is coaxial with the bonnet stem, extends
from a shaft aperture in the operator housing and forms an abutting
relationship with the bonnet assembly without the shaft and bonnet
assembly being held together within the operator housing.
16. The actuator of claim 14, wherein the contact member includes
an internally threaded bore adapted to receive an external threaded
surface of the bonnet stem.
17. The actuator of claim 14, further comprising: a seal assembly
disposed within a shaft aperture of the operator housing, the seal
assembly sealing an annulus between an inside diameter of the shaft
aperture and an outside surface of a shaft coaxial with the bonnet
stem and extending through the shaft aperture; and a retainer ring
disposed within the shaft aperture above the seal assembly for
retaining the seal assembly within the shaft aperture, the retainer
ring accessible from the exterior of the actuator to permit removal
of the retainer ring and seal assembly without removing the
operator assembly from the bonnet assembly.
18. The actuator of claim 14, further comprising: a flexible
diaphragm covering a portion of the operator member and isolating a
chamber within the operator housing; and a diaphragm retainer
having external threads threaded to a central internally threaded
aperture of the operator member, wherein the diaphragm retainer
provides a circular groove disposed therein for receiving a seal
that engages the flexible diaphragm sandwiched between the operator
member and the diaphragm retainer.
19. The actuator of claim 14, wherein the contact member defines a
downstop surface that limits travel of the contact member due to
engagement with a stop surface fixed relative to the valve
body.
20. The actuator of claim 14, wherein the contact member includes a
nut portion protruding from a center region thereof, which is
coaxial with the bonnet stem and surrounded by the drive surface.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 10/988,957, file Nov. 15, 2004, which is a
divisional of U.S. application Ser. No. 10/244,376, filed on Sep.
16, 2002, and now U.S. Pat. No. 6,854,704, issuing Feb. 15, 2005,
which is a continuation of U.S. application Ser. No. 09/888,194,
filed on Jun. 23, 2001, and now U.S. Pat. No. 6,450,477, issuing
Sep. 17, 2002, which is a continuation of U.S. application Ser. No.
09/538,881, filed on Mar. 30, 2000, and now U.S. Pat. No.
6,250,605, issuing Jun. 26, 2001, which is a continuation of U.S.
application Ser. No. 08/968,904, filed on Nov. 6, 1997, and now
U.S. Pat. No. 6,089,531, issuing Jul. 18, 2000, which is a
continuation of U.S. application Ser. No. 08/206,424, filed on Mar.
4, 1994, and now abandoned. Each of the above applications is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to an actuator
apparatus and method and, more particularly, to a valve actuator
including a bonnet assembly having an improved downstop mechanism
that is rotatably free with respect to a floating top shaft and
engageable with respect to a replaceable operator without affecting
bonnet stem drift adjustment.
[0004] 2. Description of the Related Art
[0005] Gate valves are generally comprised of a valve body having a
central axis aligned with inlet and outlet passages, and a space
between the inlet and outlet passages in which a slide, or gate,
may be moved perpendicular to the central axis to open and close
the valve. In the closed position, the gate surfaces typically seal
against sealing rings which surround the fluid passage through the
valve body. Gate valves have been used for centuries to control the
flow of a great variety of fluids. Often the fluid to be controlled
by the gate valve is under pressure. In the petroleum industry,
gate valves are used along piping at various locations, and in
particular are used in piping referred to in the petroleum industry
as a Christmas tree, which is used as part of a drilling
operation.
[0006] Actuators to open and close the gate valves may include
manual operators, diaphragm-type operators, and hydraulic
operators. The actuator may include a bonnet assembly, which
interconnects the valve body and the valve gate, and a bonnet stem
which is movable with the gate via an operator. It is often
desirable to be able to change the operator without changing the
bonnet assembly. However, this is difficult because, among other
reasons, such a change also requires changes in up-stop and
down-stop adjustments which assure the drift of the gate is
positioned correctly in the open and closed position. If the valve
is connected to a Christmas tree or is under pressure, it may be
difficult to determine whether drift adjustments have been made
correctly when replacing the operator since the bore of the valve
is not available to receive a drift alignment check tool. Removal
of a valve under pressure in a Christmas tree to make drift
adjustments may take considerable time and cause substantial
inconvenience.
[0007] It is desirable to combine a manual operator with a
diaphragm-type or hydraulic operator for back-up and test purposes.
This combination typically results in the presence of a top shaft
extending from the operator that may also serve to indicate whether
the valve is open or closed. Because the top shaft is often exposed
to the atmosphere, it may attract contaminants that cause damage to
the top shaft seals or bearings. In the past, close tolerances have
been required in the top shaft that have exacerbated the
contaminant problems. As well, torque applied to the top shaft,
which may be caused by manual operation, may cause gate, gate seal,
or drift misalignment. Furthermore, changing the top shaft or the
top shaft seals has previously required removal of the operator
housing.
[0008] The operator typically has a maximum force capability for
applying to the bonnet stem. It is sometimes desirable to provide
additional opening/closing power on a temporary basis without
having to remove the original operator. It is also desirable that
the same operator be adaptable to various control accessories, such
as a mechanical override, hydraulic override, heat sensitive lock
open device, block open cap, electrical limit switch and/or other
electrical accessories.
[0009] Another significant problem, especially related to
diaphragm-type operators, is leakage of the diaphragms in the
region adjacent the top shaft or bonnet stem. Such leakage may be
caused by wear, loss of flexibility, and pinching or wear that
occurs should the diaphragm make contact with the diaphragm case.
This leakage may gradually develop, and may slowly reduce the
operator power.
[0010] In some cases, the positioning of the gate valves in the
Christmas tree and other types of installations may be restricted
because of piping which is supplied to operate an automatic
actuator that controls gate movement. In the past, it has been
difficult to use precisely laid piping because the position of the
operator fluid port is fixed with respect to the operator housing.
Allowing the operator to rotate with respect to the bonnet could
result in leakage or cause misalignment of the up-stop and downstop
drift adjustments of the valve gate.
[0011] Thus, there has been a long felt need in the industry to
provide an improved actuator that allows a more adaptable
installation configuration, that reduces maintenance and
installation time, and that increases long term durability. Persons
skilled in the art will appreciate the present invention which
provides solutions to these and other problems associated with
valve actuators.
SUMMARY OF THE INVENTION
[0012] The present invention relates to a valve actuator for moving
a valve between open and closed states within a valve body. The
valve actuator comprises an operator housing including a pressure
chamber and a fluid port, and an operator member movable in
response to the introduction of fluid into the pressure chamber
through the fluid port. A bonnet housing is securable to the valve
body and has a bonnet housing bore therethrough. A bonnet stem
axially moves in the bonnet housing bore and is securable to the
valve gate for moving the valve gate to the open and closed valve
states. The bonnet stem is axially movable in response to movement
of the operator member in an axial direction toward the valve body.
The bonnet stem is rotatably free with respect to a top shaft.
[0013] A downstop member rotatably and axially affixed to the
bonnet stem is used for stopping axial movement of the bonnet stem
in a direction toward the valve. The downstop is also rotatably
free with respect to the top shaft. A stop surface is fixably
positioned with respect to the bonnet housing. One or more bonnet
stem spacers are disposed on the stop surface and engageable by the
downstop to stop axial movement of the bonnet stem for selecting a
desired bonnet stem drift.
[0014] An object of the present invention is an valve actuator with
improved versatility, reduced installation and maintenance, and/or
increased life.
[0015] Another object of the present invention is an actuator which
allows removal or exchange of the valve operator while the valve is
under pressure.
[0016] Another object of the present invention is an actuator which
allows removal or exchange of the valve operator without the need
to reset drift adjustments or to examine the valve bore to
determine if drift adjustments are correct.
[0017] A feature of the present invention is a floating top stem
which requires no metal-to-metal contact during operation.
[0018] A further feature of a preferred embodiment of the present
invention is an improved diaphragm having a metal insert ring to
engage an elastomeric seal and thereby minimize or avoid in the
diaphragm which may be caused by decreased diaphragm flexibility,
leakage pinching or other reasons.
[0019] Yet another feature of present invention is a replaceable
seal cartridge that allows renewal of top stem seals without
removing the operator.
[0020] An advantage of the present invention is an economical
construction for a valve actuator that is relatively simple yet
reliable in construction, and is easy to service.
[0021] These and other objects, features, and advantages of the
present invention will become apparent from the drawings, the
descriptions given herein, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is an elevational view, partially in section, of a
diaphragm-type valve actuator in accord with the present
invention;
[0023] FIG. 1A is an elevational view, partially in section, of a
block open cap attachable to the valve actuator of FIG. 1;
[0024] FIG. 2 is an elevational view, partially in section, of a
bonnet assembly in accord with the present invention;
[0025] FIG. 3 is an elevational view, partially in section, of the
bonnet assembly of FIG. 2 including drift adjustment lengths in
accord with the present invention;
[0026] FIG. 4 is an elevational view, of a replaceable operator
without readjustment of the down-stop or up-stop drift in a bonnet
assembly in accord with the present invention;
[0027] FIG. 5 is a schematical representation of actuator accessory
connections in accord with the present invention;
[0028] FIG. 6 is an elevational view, partially in section, of a
dual actuator assembly in accord with the present invention;
and
[0029] FIG. 7 is an elevational view, partially in section, of a
hydraulic valve actuator in accord with the present invention.
[0030] While the present invention will be described in connection
with presently preferred embodiments, it will be understood that it
is not intended to limit the invention to those embodiments. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents included within the spirit of the invention.
DETAILED DESCRIPTION
[0031] Referring now to the drawings, and more particularly to FIG.
1, a diaphragm-type valve actuator 10 is shown in accord with the
present invention. Top shaft 12, which is preferably formed from
stainless steel, effectively floats with respect to top diaphragm
case 14. As a general matter, all non-stainless metallic components
in actuator 10 are preferably coated for protection against
environmental conditions. Wear bearing 16, as well as wear bearings
18 (shown in detail in FIG. 2), are preferably nonmetallic to
eliminate close tolerance problems normally associated with the
actuator top shaft and bonnet stem. The wear bearings effectively
suspend top shaft 12 and bonnet stem 20 to thereby prevent metallic
contact during operation. Thus, the wear bearings are preferably
non-metallic and made from relatively hard plastic-like materials,
such as MOLYGARD.RTM., NYLATRON.RTM. or DELRIN.RTM.. The wear
bearings and other plastic-like components discussed hereinafter
may also be made from various plastic-like materials such as, but
not limited to, nylons, thermoplastics, resins, polyurethanes,
phenolics, acetals, polyacrylates, epoxides, polycarbonates,
polyester, aramids, polymers, MOLYTHANE.RTM. 90, and
fluorelastomers.
[0032] Top shaft 12 rotates independently of and is designed to
eliminate transmission of torque to bonnet stem 20, gate 22, and/or
gate seats (not shown) when using a manual override, such as manual
override 24 shown in FIG. 5. Top shaft 12 preferably is large
enough in diameter to prevent bearing and buckling stresses when
loaded by manual override 24 or hydraulic override 26 shown in FIG.
5. (See also the dual actuator system of FIG. 6 and hydraulic
actuator of FIG. 7). A large bottom shoulder 28 on top shaft 12
prevents top shaft 12 from being expelled from actuator 10.
[0033] Top seal cartridge 30 can be removed for replacement as a
single unit without disassembling top diaphragm housing 14. Top
seal cartridge 30 is preferably formed of a plastic-like material
such as DELRIN.RTM. and is held in place by retainer ring 32 which
is preferably stainless steel. Top seal cartridge 30 incorporates
rod wiper 34 to keep the shaft sealing region therebelow clean of
dirt, grease, and other contaminants for longer life of the seals.
Rod wiper 34 is preferably made from MOLYTHANE.RTM. 90. Top seal
cartridge 30 contains dual reciprocating stem seals 36 and dual
static seals 38 to ensure seal integrity and long life. These and
other seals may be T-seals or other substantially elastomeric
seals, such as O-ring seals.
[0034] Diaphragm 40 is preferably formed of nitrile laminated with
several layers of nylon to ensure strength and flexibility for
years of service. Materials such as VITON.RTM., a fluoroelastomer,
may be used for H.sub.2S--CO.sub.2 applications. The layers of
nylon in diaphragm 40 eliminate the need for lubrication and do not
experience frictional wear. Diaphragm 40 includes stainless steel
concentric insert seal ring 42 bonded thereto to act in conjunction
with a static O-ring face seal 44, which is provided in the
diaphragm retaining nut 46. This seal eliminates leakage in the
stem area which may normally occur due to diaphragm aging,
pinching, or reduced flexibility.
[0035] Diaphragm retaining nut 46 threadably engages diaphragm
retainer plate 48 for easy, accurate installation. On up strokes of
actuator 10, diaphragm retaining nut 46 prevents any possible
pinching of diaphragm 40 by stopping movement of bonnet stem 20
should diaphragm retaining nut 46 engage top plug 50. Diaphragm
retaining nut 46 provides dual stem seals 52 to engage and reliably
seal top shaft 12. Diaphragm retaining nut 46 is preferably formed
of stainless steel.
[0036] Diaphragm retainer plate 48 engages downstop element 54 for
downward axial movement of gate 22 via bonnet stem 20 when the
cavity defined by top diaphragm housing 14 is filled with
pressurized fluid, i.e. compressed air. Breather port 62 allows
fluid (air) to flow out of lower diaphragm housing 64 as diaphragm
retainer plate 48 moves downwardly. Downstop element 54 preferably
is connected to bonnet stem 20 via large threads designed to
withstand high load impacts and cycling for preventing changes in
drift settings, as discussed hereinafter. Downstop element is also
engaged by upper spring retainer 56 for upward movement of bonnet
stem 20 induced by spring 58 and/or pressure within valve body
60.
[0037] Top diaphragm housing 14 is sealingly secured to lower
diaphragm housing 64 by bolts 66 and nuts 68 which secure diaphragm
40 therebetween. Diaphragm 40 is thus anchored by this connection
and acts as a seal between the top diaphragm housing 14 and the
lower diaphragm housing 64. Base plate ring 70 is secured to lower
diaphragm housing 64 by bolts 72. Base plate ring 70 allows for 360
degree actuator rotation when exacting plumbing is required for
connections to control pressure inlet 74. Lower spring retainer 88
secures spring 58 into a centralized position. In FIG. 1A is shown
lock open cap 76 which threadably engages top plug 50 and is
secured to top shaft 12 with bolt 78 to secure the valve in the
open position.
[0038] FIG. 2 discloses a portion of bonnet assembly 90. Bonnet
assembly 90 is shown complete with spring 58 in FIG. 4. Preferably
stainless steel stem spacers 92 are positioned on top of bonnet
ring 94. Stem spacers 92 are used to determine the downward stop
drift by controlling the length of the stroke of bonnet stem 20
toward valve body 60. Packing cartridge 96 acts in a similar manner
as top seal cartridge 30 to seal between bonnet stem 20 and bonnet
housing 98. Packing cartridge 96 preferably is formed of stainless
steel. Packing cartridge 96 contains O-ring seals 100. Seals 102
are preferably T-seals comprised of VITON.RTM. 90 rings with nylon
backups. Packing cartridge 96 also includes rod wipers 104 to
protect and maintain the long life of the sealing elements by
preventing contaminants in the region of the sealing elements.
[0039] Bonnet stem threads 21 are designed so that no injury to the
seals occurs when the stem is passed through packing cartridge 96.
Dual bearings 18 suspend bonnet stem 20 to preferably prevent
contact of any metal surface thereby eliminating wear and galling
to either the bonnet stem 20 or the packing cartridge 96. To
prevent rotation of bonnet ring 94 with respect to bonnet housing
98, screw 106 is tightened into the corresponding groove or inset
disposed adjacent the end portion of bonnet housing 98. Rotation of
bonnet ring 94 with respect to bonnet housing 98 may alter the
stroke length adjustments as discussed hereinafter. Bonnet ring 94
retains packing cartridge 96 in position within bonnet housing 98.
Bonnet ring 94 also preferably includes an additional seal 102 for
safety purposes.
[0040] To set the downward stroke length or drift 106 of bonnet
stem 20, stem spacers 92 are removed or added as necessary to
increase or decrease the combined spacer width 108 as indicated in
FIG. 3. In setting the bonnet stem drift, downstop 54 is first
tightened to bonnet stem 20 with drive nut 110. Bonnet stem 20 is
placed in its furthermost downward position. The position of the
gate bore (not shown) through gate 22 is determined by running an
appropriate drift tool (not shown) through valve body 60. The
number of stem spacers 92 may then be removed or added as necessary
to provide an accurate drift setting.
[0041] Secondary metal-to-metal stem seal 112 provides sealing in
the event of fire damage to the other seals and also acts as a stop
for upward movement of gate 22. The adjustment of the up-stop drift
is made in a manner dependent upon valve manufacture designs but
may typically involve threadably engaging the gate stem with the
bonnet stem and rotating until the correct adjustment is reached.
Further rotation may be prevented by such means as a pin or other
retainer means.
[0042] FIG. 4 discloses the relative ease with which various
operators 114 may be changed out without altering the up-stop and
down-stop drift as discussed hereinbefore. Thus the operator may be
exchanged with the valve under pressure. No additional drift
adjustments are necessary because the alignment is not altered and
remains accurate for the particular valve. This feature is
especially useful where it may be difficult to make drift
realignment. Base plate ring 70 may be rotated without changing the
drift to accommodate the piping to inlet 74.
[0043] FIG. 5 is a schematic disclosing numerous attachments that
can be made to upper plug 50 and inlet valve 74 of actuator 10.
Upper plug 50 preferably includes a substantially large diameter
threaded outer connection to avoid stresses when using accessories.
Clear stem protector 116 protects top shaft 12 from adverse effects
of weather, sandblasting, contaminating operating environments, and
painting. Heat sensitive lock open device 118 mechanically holds
open the actuator and valve when other safety systems are
inoperative. This device locks the device in the down position
allowing it to rise only in the event of fire. Mechanical override
24 is used to mechanically stroke the valve, and is preferably used
on low pressure valves or during installation and testing.
Electrical limit switch contact 20 permits remote indication of
gate valve position. Various types of fusible plugs 122, quick
exhaust valves 124, pneumatic relays 126, and other sensors 128 may
be used with inlet 74 and top stem 12.
[0044] In the operation of diaphragm-type actuator 10 of the
present invention, pressure is applied through fluid port 74 which
moves both diaphragm 40 and diaphragm retainer plate 48 axially
towards valve body 60. This movement engages downstop 54 to move
bonnet stem 22 downward (towards valve body 60) until downstop 54
contacts stem spacers 92, whereupon further downward movement of
bonnet stem 22 is prevented. At this point, gate 22 is properly
aligned so that the valve is open (assuming a normally configured
gate valve). If pressure is lost or purposely evacuated, the valve
is closed via pressure from spring 58 acting against downstop 54 to
move bonnet stem 22 axially away from valve body 60 until
metal-to-metal contact is made at secondary stem seal 112. This
action is referred to as fail-closed operation. If required, the
valve can be configured with a fail open gate design for vent or
blow-down systems.
[0045] FIG. 6 discloses a dual actuator system which may be used to
double the stroke power. Secondary operator 140 preferably
threadably attaches to plug 143 via connector 141. Lock down plug
154 prevents rotation of operator 140 with respect to operator 10.
Operation of secondary operator 140 is similar to that of single
actuator 10. Pressurized fluid enters-fluid port 142 causing
diaphragm plate 144 to move downwardly, thereby forcing stem
adaptor 146 and top shaft 148 downwardly. Air is vented from vent
hole 150 during the down stroke. Downstop 152 controls the down
stroke drift in the manner discussed hereinbefore.
[0046] FIG. 7 discloses a hydraulic valve actuator 200 embodiment
of the present invention. Top shaft 202 is kept clean via rod wiper
204 disposed within removable top plug 206. Dual wear bearings 208,
preferably formed of MOLYGARD.RTM., are used to support top shaft
202. Top plug 206 also includes a POLYPAK.RTM. seal 210, preferably
formed of NITROXILE.RTM.. Hydraulic pressure moves piston 212
axially downwardly to move downstop 214 into engagement with stem
spacers 216 as described hereinbefore. Piston 212 floats on
preferably non-metallic wear bearings 218 and is further sealed
with seals 220. Upper spring retainer 222 applies force from coil
224 to move downstop 214 upwardly. Base plate ring 226 is bolted to
housing 228 and provides support for lower spring retainer 230 as
described with respect to diaphragm-type actuator 10.
[0047] The foregoing detailed disclosure and description of the
invention is illustrative and explanatory thereof, and it will be
appreciated by those skilled in the art, that various changes in
the size, shape and materials as well as in the details of the
illustrated construction, reliability configurations, or
combinations of features of the various valve actuator elements of
the present invention may be made without departing from the spirit
of the invention.
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