U.S. patent number RE29,322 [Application Number 05/622,601] was granted by the patent office on 1977-07-26 for valve and actuator assembly.
This patent grant is currently assigned to Teledyne Merla, div. of Teledyne, Inc.. Invention is credited to Norman A. Nelson.
United States Patent |
RE29,322 |
Nelson |
July 26, 1977 |
Valve and actuator assembly
Abstract
A valve and actuator assembly having a mechanism adapting such
assembly for remote actuation by a pressure medium such as
hydraulic or pneumatic fluid and including means for controlling
the development of resultant forces acting upon the valve stem of
the valve. The valve and actuator assembly includes safety means
for rendering the valve safe in response to the development of
predetermined unsafe conditions and is adapted with a manual
override system allowing the valve to be manually opened or closed
regardless of the condition of the safety means. Mechanical or
fluid actuated interlock means is provided to render fluid
actuating means inoperative and is also provided with means for
rendering the mechanical override inoperative. The assembly is
adapted to lock out the fluid actuator system to allow the assembly
to be serviced without risk of inadvertent actuation by automatic
systems. Effluent pressure may be communicated to the outer
extremity of the valve stem to balance the force applied to the
inner extremity of the valve stem by effluent pressure within the
valve.
Inventors: |
Nelson; Norman A. (Houston,
TX) |
Assignee: |
Teledyne Merla, div. of Teledyne,
Inc. (Garland, TX)
|
Family
ID: |
26880513 |
Appl.
No.: |
05/622,601 |
Filed: |
October 15, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
184837 |
Sep 29, 1971 |
03765642 |
Oct 16, 1973 |
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Current U.S.
Class: |
251/14; 251/327;
251/282 |
Current CPC
Class: |
F16K
3/0254 (20130101); F16K 31/143 (20130101) |
Current International
Class: |
F16K
31/14 (20060101); F16K 31/143 (20060101); F16K
3/02 (20060101); F16K 003/02 (); F16K
031/143 () |
Field of
Search: |
;251/327,282,326,329,14 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenthal; Arnold
Attorney, Agent or Firm: Jackson; James L.
Claims
Having thus fully described my invention, I claim:
1. A valve and actuator assembly comprising:
valve body means defining a valve chamber and having flow passage
means intercepting said valve chamber;
seat means disposed within said valve chamber about said flow
passage means;
gate means being movably disposed within said valve chamber and
having sealing engagement with said seat means, said gate having a
flow port for registry with said flow passage means to conduct the
flow of effluent through said valve and having an imperforate
portion to block the flow of effluent;
bonnet means defining a closure for said valve chamber;
fluid motor means being carried by said bonnet means and having
piston means movably disposed therein;
valve stem means having upper and lower extremities, the lower
extremity being connected to said gate means and being connected to
said piston means, said valve stem means cooperating with said
valve body to define a first pressure responsive area of said stem
means;
stem drive means engaging said stem means and being operative to
impart reciprocal movement to said stem means;
balancing means carried by said stem means and cooperating with
said stem drive means to define a second pressure responsive area
of said stem means; and
means communicating effluent pressure from said valve chamber to
each extremity of said valve stem and causing pressure induced
forces acting on said first and second pressure responsive areas of
said stem to be substantially balanced.
2. A valve and actuator assembly as recited in claim 1:
said fluid motor means comprising a closed piston housing being
fixed to said bonnet and having top and bottom walls and a
generally cylindrical wall;
said piston dividing said housing into first and second
chambers;
means communicating pressurized actuating fluid into said first
chamber to impart movement to said piston and said valve stem in
one direction;
means venting said second chamber; and
means urging said piston in a direction opposing said one
direction.
3. A valve and actuator assembly as recited in claim 1:
said means communicating effluent pressure from said valve chamber
to each extremity of said valve stem comprising passage means
defined axially through said valve stem.
4. A valve and actuator assembly as recited in claim 1:
said stem having threads formed thereon;
said stem drive means comprising a tubular stem drive element
received in surrounding relation about the outer extremity of said
stem, said drive element having internal threads at the lower
extremity thereof, said threads being disposed in threaded
engagement with said stem;
means establishing a first seal between said valve bonnet and said
stem and defining a first pressure responsive cross-sectional area
on said stem;
a pressure balancing piston carried by said stem and establishing a
second seal between said stem drive means and said stem and
defining a second pressure responsive cross-sectional area; and
said means communicating effluent pressure from said valve chamber
to each extremity of said valve stem causing said effluent pressure
to act simultaneously on said first and second cross-sectional
areas.
5. A valve and actuator assembly as recited in claim 4:
said means establishing said first seal comprising a first packing
retained within said bonnet and disposed in dynamic sealed
engagement with said valve stem.
6. A valve and actuator assembly as recited in claim 4:
said pressure balancing piston comprising a second packing being
carried by said valve stem and disposed in dynamic sealed
engagement with the inner surface of said tubular drive
element.
7. A valve and actuator assembly as recited in claim 4:
said means establishing said first seal comprising a first packing
retained within said bonnet and disposed in dynamic sealed
engagement with said valve stem; and
said pressure balancing piston comprising a second packing being
carried by said valve stem and disposed in dynamic sealed
engagement with the inner surface of said tubular drive
element.
8. A valve and actuator assembly as recited in claim 7:
vent passage means being defined in said tubular drive element and
venting any leakage of effluent pressure of said second packing
into said fluid motor means.
9. A valve and actuator assembly as recited in claim 4:
said fluid motor means comprising a piston housing being fixed to
said bonnet and having top and bottom walls and a generally
cylindrical wall;
said tubular drive element extending through said top wall in
sealed relation therewith; and
means closing the outer extremity of said tubular stem drive
element and defining a pressure balancing chamber outwardly of said
valve stem.
10. A valve and actuator assembly as recited in claim 9:
said means communicating effluent pressure from said valve chamber
to each extremity of said valve stem comprising an effluent passage
formed in said valve stem; and
said effluent passage conducting pressurized effluent from said
valve chamber to said pressure balancing chamber.
11. A valve and actuator assembly as recited in claim 4:
said first and second cross-sectional areas being of substantially
equal dimension.
12. A valve and actuator assembly as recited in claim 4:
said first and second cross-sectional areas being of different
dimension.
13. A valve and actuator assembly as recited in claim 4:
means for blocking communication between said valve chamber and the
outer extremity of said valve stem in at least one position of said
stem.
14. A valve and actuator assembly as recited in claim 13:
said means for blocking communication between said valve chamber
and the outer extremity of said valve stem comprising a first seat
surface defined on said stem inwardly of said passage means;
a second seat surface defined by said bonnet; and
said first and second seat surfaces being brought into sealed
engagement upon movement of said stem to the outermost position
thereof.
15. A valve and actuator assembly comprising:
valve body means defining a valve chamber and having flow passge
means intercepting said valve chamber;
gate means being movably disposed within said valve chamber and
having a flow port for registry with said flow passage means to
conduct the flow of effluent through said valve and having a solid
portion to block the flow of effluent;
bonnet means defining a closure for said valve chamber;
a fluid motor being carried by said bonnet and having a housing
defined by top and bottom walls and a generally cylindrical
wall;
a piston being .[.removably.]. .Iadd.movably .Iaddend.disposed
within said housing and dividing said housing into first and second
chambers;
means communicating pressurized actuating fluid into said first
chamber to impart movement to said piston and said valve stem in
one direction;
means venting said second chamber;
means imparting a force to said piston in a direction opposing said
one direction;
valve stem means interconnecting said gate means and said piston,
said valve stem having upper and lower extremities and cooperating
with said valve body to define a first pressure responsive area of
said stem;
stem drive means engaging said stem means and being operative to
impart reciprocal movement to said stem means;
balancing means carried by said stem means and cooperating with
said stem drive means to define a second pressure responsive area
of said stem means; and
means communicating effluent pressure from said valve chamber to
each extremity of said valve stem and causing pressure induced
forces acting on said first and second pressure responsive areas of
said stem to be substantially balanced.
16. A valve and actuator assembly as recited in claim 15:
said stem drive means being a tubular stem drive element received
about the outer extremity of said stem and being disposed in
threaded engagement with said stem;
means establishing a first seal between said valve bonnet and said
stem and defining a first cross-sectional area of said stem;
means establishing a second seal between said stem drive means and
said stem and defining a second cross-sectional area of said stem;
and
said means communicating effluent pressure from said valve chamber
to each extremity of said valve stem causing said effluent pressure
to act simultaneously on said first and second cross-sectional
areas.
17. A valve and actuator assembly as recited in claim 15:
said stem drive means being a tubular stem drive element received
about the outer extremity of said stem and being disposed in
threaded engagement with said stem;
a first packing being retained within said valve bonnet and being
disposed in dynamic sealed engagement with said valve stem; and
second packing means being carried by said valve stem and disposed
in dynamic sealed engagement with said tubular drive element.
18. A valve and actuator assembly as recited in claim 17:
said tubular drive element extending through said top wall in
sealed relation therewith;
means for imparting movement to said tubular drive element.
19. A valve and actuator assembly as recited in claim 18:
bearing means being carried by said closed housing of said fluid
motor;
flange means being carried by said tubular stem drive element;
and
said flange means being engagable with said bearing means to
restrict outward movement of said tubular stem drive element.
20. A valve and actuator assembly as recited in claim 15:
means for venting any effluent pressure leaked past said second
seal past said piston and into said second chamber of said fluid
motor.
21. A valve and actuator assembly as recited in claim 15:
said piston having a central vent receptacle;
said tubular stem drive element being received within said vent
receptacle;
means establishing a seal between said piston and said tubular stem
drive element and cooperating with said piston and tubular stem
drive element to define a leakage vent chamber; and
a port defined in said piston and communicating said leakage vent
chamber with said second chamber of said fluid motor.
22. A valve and actuator assembly as recited in claim 15:
said fluid motor means having mechanical means for selectively
preventing fluid actuation of said fluid motor means.
23. A valve and actuator assembly as recited in claim 15:
said stem drive means threadedly engaging said valve stem and
extending outwardly of said housing;
stop shoulder means being defined on said stem drive means; and
fluid motor lock-out means adapted to be interposed between said
fluid motor means and said stop shoulder means to prevent fluid
actuation of said fluid motor means.
24. A valve actuator assembly as recited in claim 23:
said lock-out means comprising sleeve means disposed about said
stem drive means;
lock-out bearing means being carried by said housing; and
said lock-out means being interposed between said lock-out bearing
means and said stop shoulder means.
25. A valve and actuator assembly as recited in claim 15:
said stem drive means comprising a rotatable element being disposed
in threaded engagement with said valve stem means and extending
through said top wall of said housing;
means defining an internal .Iadd.stop .Iaddend.shoulder on said
housing; and
thrust shoulder means being carried by said stem drive means within
said housing and being engageable with said internal stop shoulder
to limit axial movement of said stem drive means in one
direction.
26. A valve and actuator assembly as recited in claim 25:
said thrust shoulder means being removable from said stem drive
means to render said stem drive means inoperative.
27. A valve and actuator assembly as recited in claim 15:
adjustable stop means being carried by said piston;
means facilitating adjustment of the position of said stop means
relative to said piston; and
said stop means engaging a portion of said fluid motor to limit
movement of said piston, said valve stem means and said gate means
in one direction to positively align said flow port with said flow
passage means.
28. A valve and actuator assembly as recited in claim 27:
said means facilitating adjustment of said stop means comprising
threads formed on said piston;
said stop means being disposed in threaded engagement with said
threads of said piston; and
lock means carried by said stop means and being operative to lock
said stop means relative to said piston.
29. A valve and actuator assembly as recited in claim 15:
means defining a cushioning chamber within said housing; and
means being movable into said cushioning chamber upon movement of
said piston under influence of said force imparting means and
compressing a quantity of fluid within said cushioning chamber to
dissipate energy imparted to said piston by said force imparting
means thereby cushioning travel of said piston means at one
extremity of travel of said piston means.
30. A valve and actuator assembly as recited in claim 29:
said means defining a cushioning chamber comprising a cushioning
recess defined in said top wall of said housing; and
said means being movable into said cushioning chamber being a
thrust shoulder carried by said drive stem means and being received
in close fitting relation within said cushioning recess.
31. A valve and actuator assembly as recited in claim 15:
position indicator means being carried by said fluid motor means
and being movable responsive to both fluid actuation or mechanical
actuation of said valve stem to indicate the position of said gate
means.
32. A valve and actuator assembly as recited in claim 31:
said bottom wall of said housing having an aperture formed therein;
and
said piston indicator means being an elongated member carried by
said piston and extending through said aperture. .Iadd. 33. A valve
and actuator assembly comprising:
valve body means defining a valve chamber and having flow passage
means intercepting said valve chamber;
gate means being movably disposed within said valve chamber and
having a flow port for registry with said flow passage means to
conduct the flow of effluent through said valve and having a solid
portion to block the flow of effluent;
bonnet means defining a closure for said valve chamber;
a fluid motor means attached to said bonnet means and having a
housing defined by top and bottom walls and a generally cylindrical
wall;
a piston being movably disposed within said housing and dividing
said housing into first and second chambers;
means communicating pressurized actuating fluid into said first
chamber to impart movement to said piston and said valve stem in
one direction;
means venting said second chamber;
means imparting a force to said piston in a direction opposing said
one direction;
valve stem means interconnecting said gate means and said
piston;
stem drive means engaging said stem means and being operative to
impart reciprocal movement to said stem means;
means defining an internal shoulder on said top wall of said
housing;
thrust shoulder means being carried by said stem drive means within
said housing and being engageable with said internal shoulder to
limit axial movement of said stem drive means in one direction;
passageway means being defined in said piston to vent said
actuating fluid from said first chamber into said second chamber;
and
vent seal means being positionable in sealing relation between said
stem drive means and said piston to block said passageway means and
being positionable in non-sealing relation with said piston to open
said
passageway means. .Iaddend..Iadd. 34. A valve and actuator assembly
as recited in claim 33 wherein:
said stem drive means is a tubular stem drive element received
about the outer extremity of said stem and being disposed in
threaded engagement with said stem,
said stem drive means extending outwardly through said housing of
said fluid motor means and having a dynamically sealed relationship
with said housing of said fluid motor means. .Iaddend..Iadd. 35. A
valve and actuator assembly as recited in claim 33, wherein
vent seal surface means is formed by said piston;
seal retainer means is provided on said stem drive means; and
said vent seal means is positively supported by said seal retainer
means. .Iaddend..Iadd. 36. A valve and actuator assembly
comprising:
valve body means defining a valve chamber and having flow passage
means intercepting said valve chamber;
gate means being movably disposed within said valve chamber and
having a flow port for registry with said flow passage means to
conduct the flow of effluent through said valve and having a solid
portion to block the flow of effluent;
bonnet means defining a closure for said valve chamber;
a fluid motor means attached to said bonnet means and having a
housing defined by top and bottom walls and a generally cylindrical
wall;
a piston being movably disposed within said housing and dividing
said housing into first and second chambers;
means communicating pressurized actuating fluid into said first
chamber to impart movement to said piston and said valve stem in
one direction;
means venting said second chamber;
means imparting a force to said piston in a direction opposing said
one direction;
valve stem means interconnecting said gate means and said piston,
said valve stem cooperating with said body to define a first
pressure responsive area of said stem;
stem drive means engaging said stem means and being operative to
impart reciprocal movement to said stem means;
balancing means being provided for said stem means and cooperating
with said stem drive means to define a second pressure responsive
area of said stem means;
means communicating effluent pressure from said valve chamber to
each of said pressure responsive areas of said valve stem means and
causing pressure induced forces acting on said first and second
pressure responsive areas of said stem means to be substantially
balanced;
means defining an internal shoulder on said top wall of said
housing;
thrust shoulder means being carried by said stem drive means within
said housing and being engageable with said internal shoulder to
limit axial movement of said stem drive means in one direction;
passageway means being defined in said piston to vent said
actuating fluid from said first chamber into said second chamber;
and
vent seal means being positionable in sealing relation between said
stem drive means and said piston to block said passageway means and
being positionable in non-sealing relation with said piston to open
said
passageway means. .Iaddend..Iadd. 37. A valve and actuator assembly
as recited in claim 36 wherein:
said stem drive means is a tubular stem drive element received
about the outer extremity of said stem and being disposed in
threaded engagement with said stem, said stem drive means extending
outwardly through said housing of said fluid motor means and having
a dynamically sealed relationship with said housing of said fluid
motor means. .Iaddend.
Description
FIELD OF THE INVENTION
This invention relates generally to gate valves and more
particularly concerns gate valves of the rising stem type having
power actuators associated therewith for remote control of gate
valves.
BACKGROUND OF THE INVENTION
Due to the remote locations of oil wells and pipelines, it is often
desirable that valves at such locations be provided with means
permitting remote control. Remote or automatic control is essential
for automation programs and safety systems. One common method of
providing such control has been to attach a fluid actuated piston
operator to the stem of a rising stem gate valve. By pressurizing
one side or the other of the piston, the valve can be opened or
closed from a point remote from the valve. To provide fail-safe
operation in the event that one of the lines carrying pressure
fluid to the operator is ruptured or if for some other reason the
remote control system fails, it is desirable to provide such valves
with means to automatically position the valve in a predetermined
safe position. In such event, it is also desirable to have the
valve provided with means permitting manual operation. It is also
desirable to render a manual operating system inoperative to
provide a safe environment for a worker conducting repair or
maintenance on a flow system controlled by a valve to which the
operator might be attached.
It is also desirable to provide an actuator system that ensures
against actuation of the valve by remotely located automatic
sensors. If the valve is actuated while being serviced the valve
and actuator assembly could be damaged or other damage could
occur.
Where the valve is being employed to control high pressure fluid
such fluid generally acts upon the surface area defined by the
cross-sectional area of the valve stem and develops a force acting
on the stem that must be overcome by the fluid motor of the
actuator and by the manual override system. It would be desirable
to eliminate or render inoperative the force ordinarily acting on
the valve stem threads to permit easy manual operation.
SUMMARY OF THE INVENTION
In one form of the present invention all of these functions are
accomplished. A rising stem valve is provided with a piston type
valve actuator. To ensure that the valve will automatically
completely close in the event that remote control system fails, a
biasing means is attached to the piston of the actuator. The
biasing means is of a sufficient magnitude so that if pressure on
the piston fails, the valve will automatically completely close or
open as desired. By locating the port in bottom half of the gate,
the valve will automatically open upon failure of the remote
control system. To permit manual operation of the valve after such
failure and automatic positioning, manual operating means are
provided. The stem of the valve is threaded into the stem of the
manual actuator and by rotating the hand-wheel attached to the stem
of the operator, the stem of the valve disengages from its
connection with the stem of the operator and manually moves the
gate.
Pressure is transmitted through the valve stem to a pressure
chamber located outwardly of the stem which serves to balance the
fluid pressure forces acting on the stem to allow the valve to be
manually actuated by relatively small actuator torque forces even
when the valve is employed to control high pressure fluid.
It is a primary object of the present invention to provide manual
operating means for remote controlled piston operated valves.
It is a general object to provide a piston operated gate valve
incorporating means for automatic fail-safe positioning and manual
operation.
It is another object to provide simple efficient means for manually
operating a piston operated valve.
It is another object of the present invention to provide a
mechanism for balancing the pressure acting on the valve stem.
It is an even further object to provide a mechanism for locking out
an actuator to prevent operation thereof, if desired.
Other and further objects of the invention will be obvious upon an
understanding of the illustrative embodiments about to be
described, or will be indicated in the appended claims, and various
advantages not referred to herein will occur to one skilled in the
art upon employment of the invention in practice.
Preferred embodiments of the invention have been chosen for
purposes of illustration and description and are shown in the
accompanying drawings, forming a part of the specification,
wherein:
FIG. 1 is a vertical sectional view of the valve of the present
invention incorporating both the safety feature and the manual
operating feature showing the valve in the open position as result
of being actuated by the fluid actuator.
FIG. 2 is a fragmentary sectional view of the structure of FIG. 1
illustrating the valve and actuator structure after closure of the
valve.
FIG. 3 is a fragmentary sectional view of the structure of FIG. 1
showing the valve and actuator structure after opening thereof by
the manual override system.
FIG. 4 is a fragmentary sectional view of the structure of FIG. 1
illustrating employment of a spacer to permit positive upward
retraction of the valve stem.
FIG. 5 is a fragmentary sectional view of the structure of FIG. 1
illustrating the actuator assembly without a manual override
mechanism thereby illustrating ready adaptation of the override
mechanism to the actuator assembly.
FIG. 6 is a sectional view of a modified embodiment of the present
invention.
FIG. 7 is a fragmentary sectional view of a valve operator
representing a further modified embodiment of the present invention
and illustrating a mechanism for selectively rendering the valve
operator inoperative.
FIG. 8 is a fragmentary sectional view illustrating the safety
mechanism of FIG. 7 in the position deactivating the valve
operator.
FIG. 9 is a fragmentary sectional view illustrating a modified
safety mechanism for rendering the valve actuator inoperative.
FIG. 10 is a fragmentary sectional view illustrating the safety
mechanism of FIG. 9 in the deactivated position thereof.
FIG. 11 is a fragmentary sectional view of the valve and actuator
assembly illustrating a further modified safety mechanism for
rendering the valve actuator system inoperative.
FIG. 12 is a fragmentary elevational view illustrated partially in
section and showing a valve actuator mechanism representing a
modified embodiment of the present invention.
FIG. 13 is a fragmentary elevational view illustrated partially in
section and showing a valve actuator mechanism representing a
further modified embodiment of the present invention.
Referring now to the drawings and first to FIG. 1, a rising stem
gate valve 10 is provided with a piston type valve actuator 12.
The housing 14 of the valve 10 is formed of a casting within which
a chamber 16 is defined to receive the operating parts of the
valve. Extending from the chamber 16 are aligned flow passages 18
and 20. The inner ends of the flow passages are provided with seats
22 and 24. Interposed between the seats 22 and 24 is a gate member
26. The gate assembly 26 has a passage 28 which registers with the
passages 18 and 20 in open position and a solid portion which
blocks flow in closed position. As will be explained subsequently,
locating the passage 28 in the top half of the gate assembly will
cause the valve to automatically close upon loss of pressure in the
remote control system and locating the passage in the bottom half
of gate assembly, will cause the valve to automatically open.
Nonrotatably attached to the top of the gate 26 is a stem 30 which
extends through a bonnet 32 and packing 34. Movement of the stem 30
results in corresponding movement of the gate 26. The upper end of
the stem is provided with male threads 35, the purpose of which
will be explained subsequently.
Attached to the top of the bonnet 32 is the piston operator 12. The
body of the operator is comprised of a base member 36, received at
the top of the bonnet 32, a piston cylinder 38 and a cap 40 closing
the top end of piston cylinder 38. The cap 40, if desired, may be
formed integrally with the piston cylinder 38 or it may be attached
to the piston cylinder in any desirable manner. The piston cylinder
is secured to the base member 36 by a snap ring 42 received within
complementary grooves formed within the base member and the piston
cylinder. A connector element 44 is threadedly secured to the upper
extremity of the bonnet 32 and retains the packing 34 in bonnet 32
and threadedly receives a retainer element 46 that engages the base
member 36 and retains the base member in immovable relation with a
shoulder 48 defined on bonnet 32. The retainer member 46
effectively provides positive alignment of the base member relative
to the bonnet member and effectively prevents the slight movement
that is ordinarily found in pneumatic and hydraulic valve actuators
of this general type. A stop member 50 is also threadedly received
by the connector element 44 and is secured in position by a bolt
member or set screw 52. The stop member 50 is adapted to be engaged
by a piston member 54 movably received within the cylinder 38 in
order to limit downward movement of the piston member and thereby
positively locate the valve port 28 with the valve passages 18 and
20 in the open position thereof. A compression spring member 56 is
interposed between the base member 36 and the piston 54 and is
operative to maintain a bias urging piston member 54 upwardly
against the forces developed by fluid pressure above the piston and
acting to drive piston member 54 downwardly. The piston divides the
actuator housing into a lower chamber 58 that may be vented to the
atmosphere by a vent aperture 60 and an upper chamber 62 adapted to
receive pressurized actuating fluid introduced through an inlet
aperture 64.
The actuator may be provided with a bearing retainer 66 that is
threadedly received by an internally threaded boss 63 connected to
or formed integrally with the cap 40. The bearing retainer is
operative to maintain a thrust bearing member 70 in engagement with
a thrust shoulder 72 defined by end cap 40.
The upper threaded extremity of the stem 30 may be received by the
internal threads 74 of a tubular drive element 76 that extends in
movable relation through an aperture 78 defined within the bearing
retainer 66. A sealing member 80 maintains a dynamic seal between
the bearing retainer 66 and the exterior cylindrical surface of the
tubular drive member 76. The tubular drive member may be provided
with an internal bore 82 of substantially the same cross-sectional
dimension as the cross-sectional dimension defined by the internal
diameter 84 of the packing member 34 when sealing on stem 30.
An outer packing member 86 may be received by the upper extremity
of the stem 30 and may be maintained in secure relation with the
stem by a snap-ring 89 or the like and is operative to maintain a
dynamic seal between the valve stem and the internal wall 82 of
tubular drive element 76. For purposes of the present invention the
outer packing is intended to be considered a part of the valve
stem. The upper extremity of tubular drive element 76 is closed by
a cap or, if desired, by a grease fitting 88 threadedly received
within the tubular drive element and being provided with a fluid
passage 90 that is controlled by a spring biased check valve 92 to
allow the introduction of fluid such as lubricant into a pressure
balancing chamber 94 defined outwardly of the packing 86 but
preventing fluid pressure within chamber 94 from exiting through
the passage 90.
The valve stem 30 may be provided with an axial passageway 96 that
is functional to conduct pressurized fluid from within the chamber
16 upwardly through the valve stem and gate connector element to
the pressure balancing chamber 94, or if desired the passage 96 may
terminate above the internal shoulder 104 as shown at 95 in FIG. 2.
It is evident therefore that the upper and lower extremities of the
valve stem 30, each being of substantially the same dimension, are
subjected to the same fluid pressure and therefore cause forces to
be developed by the effluent pressure at each extremity of the
valve stem that are substantially balanced and which cooperate to
develop a negligible resultant force regardless of the fluid
pressure being controlled by the valve 10.
In the event it is desirable to have a downward or upward resultant
force acting upon the valve stem, such can be readily accomplished
by providing differential stem areas of specifically designed
cross-sectional area. For example, as illustrated in FIG. 6, if the
cross-sectional area of the valve stem D.sub.2 is equal to the
cross-sectional area D.sub.U of the piston the forces acting upon
the valve stem will be balanced. If the cross-sectional area of the
valve stem D.sub.2 is greater than the cross-sectional area of the
piston D.sub.U, a bias will be exerted upwardly on the valve stem.
Likewise, a downward bias will be exerted upon the valve stem if
the cross-sectional area of the piston D.sub.U is greater than the
cross-sectional area of the stem D.sub.2. This feature effectively
provides that the only force acting on the threads is that of
moving the gate and overcoming the friction of the stem seal. At
the same time, the stem threads are not exposed to the fluids
contained in the valve chamber 16.
A handwheel 98 may be secured to the upper extremity of the tubular
drive member 76 in any desirable manner and may be rotated causing
the threaded engagement between the drive element 76 and the
threads 35 of valve stem 30 to reciprocate the valve stem.
The tubular drive element 76 may be provided with a thrust shoulder
100 that is removably retained in assembly with the tubular drive
element by a retainer ring 101 in the form of a snap-ring or
segmented ring received within a groove formed in the periphery of
the tubular drive element. A set screw 103 or the like may be
employed to secure the retainer ring and thrust shoulder in
assembly.
As illustrated in FIG. 1, the valve is disposed in its open
position and the manual override system defined by the tubular
drive element, the handwheel, and the threads of the valve stem are
disposed in the inoperative positions thereof thereby allowing the
piston 54 freedom of movement downwardly under the influence of
hydraulic or pneumatic pressure and upwardly under combined bias
forces of the spring member 56 and pressure contained in the valve
chamber 16 acting in the stem area.
With reference now to FIG. 2, the valve and actuator assembly is
disposed in the position of normal closure by the spring member
urging the piston member upwardly causing a valve stem shoulder 102
to engage an internal shoulder 104 defined within the bonnet
structure 32. This serves as the upward movement stop of the stem
30.
As illustrated in FIG. 3, the valve and actuator assembly are
disposed in the position achieved after actuation thereof to the
open position by the manual override mechanism. To open the valve,
handwheel 98 will be rotated thereby causing the tubular drive
element to be driven upwardly on the valve stem threads until the
shoulder 100 engages the thrust bearing member 70. After this has
occurred the tubular drive element can no longer move upwardly and
continued rotation of the hand wheel will force the valve stem 30
to move downwardly thereby causing valve element 26 to move
downwardly aligning the port 28 with the inlet and outlet passages.
In this condition application of fluid pressure into the chamber 62
of the actuator will not cause movement of the piston 54 because
the piston will be disposed in engagement with the stop member 50.
The compression spring 56 is also inoperative under this condition
and is not capable of urging the piston member 54 upwardly. The
valve and actuator assembly, under this condition, may be serviced
without danger to servicing personnel because movement of the valve
and actuator assembly will not occur in the event the actuator
assembly is inadvertently energized by remote sensors or the
like.
With reference now to FIG. 4, the valve and actuator assembly may
be provided with means for manually driving the valve element
toward both the open and closed positions thereof. According to the
present invention, such means may conveniently take the form
illustrated where a thrust bearing member 106 is received within an
annular bearing retainer extension 108 and is disposed about the
movable drive element 76. A lock-out sleeve 110 is received about
the upper extremity of tubular drive element 76 and is received in
thrust engagement by the bearing member 106. The retainer sleeve is
also disposed for engagement by a shoulder 112 of the hand wheel
structure 98 thereby preventing downward movement of the hand wheel
and tubular drive element when it is desired to temporarily prevent
actuation of the power actuator system. Upward movement of the
tubular drive element 76, under this condition, will be prevented
by engagement between the thrust shoulder 100 and thrust bearing
member 70. Since the tubular drive element will not be capable of
moving linearly under this condition, it is obvious that the piston
member 54 will not move downwardly under application of pressurized
hydraulic or pneumatic fluid into the chamber 62 through inlet
passage 64. Likewise, the compression spring 56 will be unable to
impart upward movement to the piston 54 upon bleeding of the
pressurized hydraulic fluid from actuation chamber 62. Upon
rotation of the hand wheel and tubular drive element clockwise the
threaded connection between the tubular drive element and the valve
stem will impart upward movement to the valve stem thereby moving
the valve element to its closed position. Likewise, upon rotation
of the hand wheel 98 in counterclockwise manner, the valve stem,
along with piston 54 and compression spring 56, will be moved
upwardly, thereby imparting upward movement to valve element 26 and
closing the valve.
The lock-out sleeve 110 and thrust bearing 106 are intended only
for temporary use in the event it is desirable to completely lock
out the power actuation system and rely only upon manual actuation
to achieve opening and closing of the valve. The retainer sleeve
and bearing assembly is easily installed with the valve and
actuator system in the FIG. 2 or FIG. 3 positions thereof simply by
removing the hand wheel structure and placing the retainer sleeve
about the tubular drive element after which the hand wheel
structure may be replaced. Alternatively, it may be appropriate to
install semi-cylindrical retainer sleeve segments about the tubular
drive element, which of course can be accomplished without
necessitating removal of the hand wheel 98. The retainer segments
may simply be implaced and retained by the annular extension 108 or
in the alternative may be provided with any suitable means to
maintain the segments in a generally cylindrical assembly
subsequent to installation thereof.
With reference now to FIG. 5 it may be desirable to completely
disconnect the hand wheel structure 98 from the tubular drive
element 76 and remove thrust shoulder 100 to make it mechanically
impossible for unauthorized manual actuation of the gate valve
structure. Also, under these conditions, the tubular drive element
76 may be provided appropriate indicia to serve as a position
indicator by which the position of the gate element 26 may be
monitored.
Referring now to FIG. 6, a modified embodiment of the present
invention may conveniently take the form illustrated, where a valve
10 having a valve body 14 may include a bonnet structure 140 that
may be bolted or otherwise secured to the valve body. A stem
packing 142 may be retained within a stuffing box 144 defined
within the bonnet and may be retained in position by a retainer
element 146 surrounding a valve stem 148.
The bonnet 140 may be provided with a reduced diameter upper
extremity providing an annular shoulder 150 that is engaged by the
base 152 of a valve actuating mechanism, illustrated generally at
154. The upper extremity of the bonnet 140 may be provided with
external threads 156 which receive the internal threads of a
retainer element 158 to secure the base 152 in assembly with the
bonnet. The base 152 may be provided with a recess 160 that
receives a locator pin 162 therein when the base portion 152 of the
valve actuator is properly aligned with respect to the bonnet
structure.
A piston cylinder 164 may be retained in assembly with the base 152
by a snap-ring and bolt retainer assembly. A plurality of bolts 164
may be threadedly received by the base 152 and may connect a
cylinder retainer 166 to the base to restrain downward movement of
the cylinder relative to the base. A snap-ring 168 is disposed
within a snap-ring groove formed within the cylinder 164, and
engages an annular shoulder 170 formed on the base 152 to retrain
movement of the cylinder relative to the base.
A bearing retainer 172 is threadedly received at the upper
extremity of the piston 164 and serves to restrain a thrust bearing
174 in engagement with a thrust bearing shoulder 176 defined within
a passage 178 in the upper extremity of the cylinder 164.
A tubular drive element 180 may extend through an aperture 182
formed in the bearing retainer 172 and may be provided with
internal threads 184 within the lower portion thereof that are
disposed in threaded engagement with external threads 186 defined
at the upper extremity of the valve stem 148.
The valve actuator may include a piston element 188 having an
internal generally cylindrical pocket 190 defined by a tubular
portion 192 of the piston. A sealing element 194 may be retained
within an appropriate groove formed within the upper extremity of
the tubular portion of the piston to establish sealing engagement
with a cylindrical surface 196 defining the outer periphery of the
tubular drive element 180. The valve stem 148 extends through an
aperture 198 formed in the lower tubular portion 192 of the piston
which aperture is provided with an internal frustoconical shoulder
200 disposed in engagement with an external frustoconical shoulder
202 defined on the valve stem. The piston is retained in assembly
with the valve stem by a piston retainer 204 that is threadedly
received by the valve stem.
An adjustable downstop element 206 may be received by external
threads 208 formed on the tubular portion of the piston 188. A set
screw member 210 may be received within the downstop element and
may lock the downstop element in any suitable position relative to
the piston. The downstop element may be employed to limit downward
movement of the piston and valve stem thereby positively aligning
the passage of the gate member with the flow passages of the
valve.
At the upper extremity of the valve stem 148 is carried a pressure
balancing piston assembly including an annular packing 212
establishing sealed engagement between the valve stem and an
internal cylindrical surface 114 of the tubular drive element 180.
Upper and lower annular retainer members 216 and 218, respectively,
are received about the upper portion of the valve stem on either
side of the packing element 212 and serve to properly position the
packing element and prevent pressure extrusion thereof. A retainer
plug 220 may be provided with an externally threaded extension
received by internal threads defined within the upper extremity of
the valve stem 148 and may provide an annular shoulder 222 engaging
the upper retainer 216 to secure the pressure balancing piston
assembly in assembled relation with the valve stem.
For the purpose of imparting movement to the piston 188 in an
upward direction, a compression spring 224 may be interposed
between the base 152 and the piston 188. In absence of fluid under
sufficient pressure above the piston 188 the compression 224 may be
operative to move the piston upwardly and bring a removable
shoulder element 226 into engagement with the bottom portion of the
thrust bearing 174. To prevent the piston element from slamming as
it is moved upwardly by the compression spring 224, the enlarged
cylindrical bore 178 about the tubular drive element 180 cooperates
with the removable shoulder 226 to serve a dash-pot function to
cushion or retard rapid movement of the piston element. This
feature effectively prevents slamming of the piston thereby
preventing damage to the piston or cylinder structure of the
actuator. A snap-ring or segment ring 228 may be received within an
annular groove formed in the tubular drive element 180 to which may
be appropriately secured the removable shoulder element 226.
Connection between the removable shoulder element 226 and the
snap-ring or segment ring 228 may be such that the shoulder element
may be removed without disassembling the tubular drive element from
the valve stem. This can be done with the valve in its closed
position with pressure inside the drive sleeve and thus make the
manual override mechanism inoperative.
A vent 230 may be formed within the tubular drive element bypassing
the internally threaded portion thereof and thereby communicating
any fluid that might leak past the pressure balancing piston
assembly into the cylindrical pocket 190. The leaked fluid will
then be vented from the cylindrical pocket through a vent aperture
232 defined in the tubular portion of the piston 188. A vent and
position indicator aperture 234 may be defined within the base 152
thereby allowing pressurized fluid passing through vent aperture
232 to exit the valve actuator and provide an indication that
repair of the pressure balancing assembly is required. A position
indicator 236 may extend through the aperture 234 and may be
physically connected to the piston 188 thereby giving a positive
external visual indication of movement of the piston as the
actuator is energized and showing the position of the piston at all
times whether the mechanism is actuated by the fluid motor or by
the manual override mechanism.
In the event it is necessary to repair or replace the pressure
balancing assembly, such can be accomplished readily by removing
the nut 238 that secures a hand wheel 240 to the upper extremity of
the tubular drive element. An internal sealed plug 242 may then be
unthreaded from within the tubular drive element thereby exposing
the retainer plug 220. After the retainer plug has been unthreaded
from its connection with the valve stem 148 the packing 212 and the
retainers 216 and 218 may readily be removed. After the pressure
balancing assembly has been replaced and has been secured by the
retainer plug 220 the plug member 242 may be rethreaded into
position, causing the sealing element 244 thereof to establish a
seal with the internal cylindrical surface 114 of the tubular drive
element, thereby positively closing the upper extremity of the
tubular drive element and preventing fluid pressure passing through
the valve stem passage 246 from being vented at the upper extremity
of the tubular drive element.
It may be desirable to provide a means for completely deactivating
the valve actuator in the event it is desired to conduct repair or
servicing operations on apparatus subjected to fluid pressure
controlled by the valve to which the actuator is affixed.
Accordingly, such means for deactivating the valve actuator may
conveniently take the form illustrated in FIGS. 7 through 11 where
a tubular drive sleeve 246 is illustrated as being provided with a
removable shoulder element 248 of similar construction as set forth
in FIG. 6. The lower extremity of the tubular drive element 246 may
be provided with an annular groove 250 within which may be received
a seal assembly 252 establishing a fluid tight seal with a
generally cylindrical surface 254 defined within a tubular
extension 256 of a piston element 258. A vent passage 260 may be
formed within the piston element and may extend from a generally
cylindrical pocket defined by the cylindrical surface 254 through
the piston structure as illustrated.
When the tubular drive element 246 is threaded onto the valve stem
262 to the .[.postion.]. .Iadd.position .Iaddend.illustrated in
FIG. 7, the vent 260 will be sealed by virtue of engagement between
the sealing element and the cylindrical wall 254. Upon movement of
the tubular drive element 246 to the FIG. 8 position thereof, the
seal between the sealing element 252 and the cylindrical wall 254
will be broken and any fluid pressure applied above the piston 258
will be vented through vent passage 260 to the underside of the
piston, thereby preventing downward actuation of the piston stem
and valve gate. It is readily seen therefore that the tubular drive
element, when unthreaded manually to the position illustrated in
FIG. 8, will render the valve actuator completely inoperative by
the pressurized fluid.
With reference now to FIGS. 9 and 10, there is disclosed a further
modified embodiment providing a pneumatic interlock feature having
the capability of venting fluid pressure to preclude fluid
actuation of the actuator. A piston 264 may be provided with a
generally centrally disposed tubular portion 266 defining a
cylindrical pocket 268. A sealing element 270 may be provided
adjacent the upper extremity of the tubular portion 266 and may
establish sealed relation with an external generally cylindrical
surface 272 formed on a tubular drive element 274. A vent
controlling sealing element 276 may be received within an annular
groove formed in the tubular drive element and may establish sealed
relation with a cylindrical surface 278 to prevent fluid pressure
from above the piston 264 from venting through a vent passage 280
defined within the piston structure. Upon movement of the tubular
drive element 274, relative to the piston 264, the annular sealing
member 276 will be moved out of contact with the cylindrical
surface 278 thereby allowing pressurized fluid to vent through the
vent passage 280 to preclude downward movement of the piston and
valve stem.
With reference now to FIG. 11, there is disclosed a further
modified embodiment of the present invention providing a pneumatic
interlock feature that is also capable of venting fluid pressure
from the valve actuator to prevent inadvertent opening or closing
movement of the valve with which the actuator is associated.
A piston 259 of the valve actuator may be provided with a generally
centrally disposed tubular portion defining a generally cylindrical
pocket having a circular planar bottom wall or seat surface 255
disposed concentrically with a bore through which the valve stem
263 extends. A vent passage 261 may be formed within the tubular
portion of the piston and may intersect the bore at a position
below the circular seat surface 255.
A tubular stem drive element 247 having a shoulder element 249
affixed thereto may be provided with internal threads that
threadedly engage external threads formed on the valve stem 263
essentially as shown in FIG. 7. The tubular drive element may be
provided with an annular seal groove 251 at the lower extremity
thereof within which may be disposed a sealing element 253 which,
as illustrated in FIG. 11, may take the form of an O-ring or any
other suitable seal configuration. The sealing element 253 is
disposed for contact with the circular seal surface 255 as the
tubular stem drive element is moved to its lowermost position,
thereby effectively blocking communication between the vent passage
and the pressure chamber of the actuator above the piston 259.
When it is desired to render the piston actuator inoperative, the
tubular drive element 249 will be rotated relative to the valve
stem causing the annular seal 253 to move out of sealing engagement
with the circular seat surface 255. When this has occurred any
pressure introduced into the pressure chamber of the valve actuator
above the piston will enter the cylindrical pocket past the tubular
drive element and will be vented through passage 261 into the lower
chamber of the valve actuator. As indicated above, the lower
chamber of the valve actuator is also vented to the atmosphere
thereby allowing any fluid pressure introduced into the upper
chamber of the valve actuator to be vented to the atmosphere.
With reference now to FIGS. 12 and 13, it may be desirable to
provide a valve structure having an internally threaded valve stem.
FIGS. 12 and 13 represent structures that facilitate employment of
the present invention in valve structures having internally
threaded valve stems.
With reference now particularly to FIG. 12 there is shown a valve
generally at 300 having a valve body 302 to which is connected a
bonnet structure 304 by bolts as shown or by any other suitable
means of connection.
A piston type valve actuator, illustrated generally at 306, may
include a base or bottom wall 308 secured to the bonnet 304 by a
retainer 310 threadedly received by an upper threaded portion of
the bonnet 304. The bonnet may include a packing assembly 312 that
establishes a dynamic seal with a valve stem 314 that is connected
at its lower extremity to the valve gate, not shown, and extends
through the bonnet structure into the valve actuator. The packing
312 cooperates with the valve stem 314 to define a cross-sectional
area D.sub.L of the valve stem that is subjected to the pressure of
the effluent controlled by the valve.
The valve actuator 306 may also include a cylindrical housing
portion similar to that illustrated in FIG. 6 having an upper wall
316 provided with a centrally located boss 318. The valve stem 314
may extend upwardly through the housing portion of the valve
actuator and the upper extremity of the valve stem 314 may be
received within a passage 320 that extends upwardly into the boss
318. The upper extremity of valve stem 314 may be provided with a
generally cylindrical surface 322 that is maintained in sealed
engagement with the upper wall 316 of the valve actuator 306 by an
annular sealing element 324 contained within an appropriate groove
provided therefor.
A rotatable actuator stem 326 may extend through the passage 320 of
the boss and may include an annular flange 328 that may be disposed
in engagement with upper and lower thrust bearings 330 and 332,
respectively, which flange and bearings may be retained in assembly
with the boss 318 by a retainer element 334 that may be disposed
about the upper extremity of the actuator stem and may be
threadedly received at the upper extremity of the boss 318. The
lower portion of the actuator stem 326 may extend through the
tubular valve stem 314 and may be provided with external threads
336 that may be received by internal threads 338 defined within the
valve stem. As the actuator stem 326 is rotated, reciprocation of
the actuator stem is restrained by the thrust bearings and the
retainer element 334. The threaded engagement between the threads
336 and 338 of the actuator stem and valve stem, respectively,
transmits the rotary movement of the actuator stem 326 into
vertical movement of the valve stem, thereby causing reciprocation
of the gate element to control the flow of effluent through the
valve.
A piston 340 may be fixed to the valve stem in any appropriate
manner and may be provided with edge portions disposed in dynamic
sealed engagement with the cylindrical side wall of the valve
actuator 306 in similar manner as illustrated above regarding FIG.
6, thereby dividing the valve actuator into upper and lower
chambers. Fluid pressure may be introduced from any appropriate
controlled source of pressurized actuator fluid into the upper
chamber above the piston 340 thereby urging the piston and the
valve stem 314 downwardly, imparting downward movement to the gate
element of the valve. Downward movement of the piston 340 may be
opposed by the bias of a compression spring 342 disposed within the
lower chamber between the base 308 and the piston 340. The
compression spring is operative to impart upward movement to the
piston 340 when the pressure within the upper chamber of the
actuator is below the level necessary to overcome the bias of the
spring 342. Closure of the valve, therefore, may be accomplished
simply by bleeding fluid pressure from the upper chamber of the
actuator to allow the compression spring 342 to move the piston
stem and gate upwardly to the closed position thereof. It is
obvious, therefore, that rupture of a control conduit supplying
pressurized actuation fluid to the upper chamber of the actuator,
will cause the spring 342 to automatically induce movement of the
piston stem and gate to a predetermined safe position. Such safe
position may be "open" or "closed," depending upon the position of
the port within the gate element.
To eliminate or control the amount of thrust force induced by the
pressure of the effluent controlled by the valve to the valve stem
314, it may be desirable to direct the pressurized effluent to act
upon an equivalent surface area at the opposite extremity of the
valve either to achieve a balanced force condition or to achieve a
resultant force biasing the valve stem in either direction thereof.
Accordingly, means for accomplishing this feature may conveniently
take the form illustrated in FIG. 12, where the actuating stem 326
is shown to be provided with an external cylindrical surface 344 of
substantially the same dimension as the cylindrical surface
disposed in contact with the packing assembly 312. A dynamic seal
may be established between the tubular upper portion of the valve
stem and the cylindrical surface 344 of the actuator stem by an
upper packing assembly 346 that may be retained in assembly with
the valve stem by a retainer member 348 disposed about the actuator
stem and threadedly received at the upper portion of the valve
stem.
The packing assembly 346 cooperates with the cylindrical surface
344 to define a cross-sectional area D.sub.U that may be of
substantially the same dimension as the cross-sectional area
D.sub.L if a balanced force condition is desired. If an unbalanced
force condition is desired, producing an upward or downward
resultant force acting upon the valve stem, the cross-sectional
area D.sub.U will, of course, be of smaller or larger dimension
than the cross-sectional area D.sub.L.
For the purpose of introducing effluent pressure into the tubular
portion of the valve stem, a passage 350 may be defined within the
lower portion of the valve stem and may open into the valve
chamber. A passage 352 may be formed in the actuator stem 326 to
.[.conduit.]. .Iadd.conduct .Iaddend.fluid pressure past the
threaded connection between the actuator stem and drive stem.
Referring now to FIG. 13, a further modified embodiment of the
present invention may incorporate a valve, illustrated generally at
354, having a valve body 356 to which may be connected a bonnet 358
by a plurality of bolts or by any other suitable means of
connection. An actuator base 360 may be secured to the bonnet 358
by a retainer element 362 threadedly received at the upper
extremity of the bonnet. A valve stem 364 may extend upwardly from
the valve through a packing assembly 366 disposed within the bonnet
with an upper tubular extremity 368 thereof received within a
passage 370 defined within a boss 372 provided on the upper wall
374 of the cylinder portion of a valve actuator illustrated
generally at 376. The tubular portion of the valve stem may be
sealed with respect to the housing by an annular sealing element
378, retained within an internal groove formed within the boss 372,
which sealing element establishes a dynamic seal with a cylindrical
surface 380 defining the exterior periphery of the tubular portion
368 of the valve stem.
A piston element 382 may be fixed in sealed relation to the tubular
portion of the valve stem in any desirable manner with its outer
periphery disposed in dynamic sealed engagement with a cylindical
wall of the actuator housing in similar manner as illustrated in
FIG. 6. Downward movement of the piston 382 may be induced by
pressurized fluid introduced from any suitable source of actuation
fluid through an inlet passage 384 into a chamber defined within
the actuator housing above the piston. The pressure of the
actuation fluid must be sufficient to overcome the force of a
compression spring 386 interposed between the base 360 and the
piston 382. The valve actuator 376 will function under the
influence of pressurized actuation fluid introduced above the
piston 382 in similar manner as discussed above regarding FIG.
12.
It may be desirable to impart movement to the gate element manually
to control the flow of fluid through the valve in the event the
piston actuator should become inoperative or, if for some other
reason, manual actuation is desired. Accordingly, a mechanism for
inducing manual actuation of the gate valve mechanism may
conveniently take the form illustrated in FIG. 13 where the tubular
portion 368 of the valve stem 364 is shown to incorporate internal
threads 388 that receive external threads 390 defined on a
rotatable actuator stem 392. A thrust flange 394 may be fixed to
the actuator stem 392 and may be disposed in engagement with upper
and lower thrust bearings 396 and 398, respectively, that are
retained in assembly with the flange and with the actuator housing
by a retainer element 400 disposed about the bearings and flange
and threadedly secured to the upper extremity of the boss 372. The
thrust bearings and flange cooperate to prevent vertical movement
of the valve stem 392 as it rotates thereby inducing vertical
movement to the valve stem 364 by virtue of the threaded connection
between the actuator stem and the tubular portion of the valve
stem. The actuator stem may be rotated by a hand wheel 402 or by
any other suitable mechanism fixed in nonrotatable relation to the
upper extremity of the actuator stem.
It may be desirable, as indicated above, to establish a balanced or
controlled force condition acting on the valve stem to allow the
valve stem to be reciprocated free by application of relatively low
torque forces applied to the actuating stem 392. A mechanism for
accomplishing such balancing or controlling of resultant forces may
conveniently take the form illustrated in FIG. 13 where a packing
element 404 is shown to be fixed to the lower extremity of the
actuator stem by a bolt 406 or by any other appropriate means and
which establishes a dynamic seal with an inner cylindrical surface
408 defined within a tubular portion of the valve stem. The seal
between the packing 404 and the cylindrical surface 408 defines a
cross-sectional area D.sub.U which may, if balanced stem force
conditions are desired, be substantially equal to a cross-sectional
area D.sub.L defined by dynamic sealed engagement between the
packing 366 and a cylindrical surface 410 defined by the lower
portion of the valve stem. In the event unbalanced force conditions
are desired, the cross-sectional area D.sub.U may, of course, be
larger or smaller than the cross-sectional area defined at D.sub.
L.
The balanced or resultant force condition will be induced by the
pressurized effluent controlled by the valve which may act through
a pressure balancing passage 412 defined within the valve stem 364
and disposed in fluid communication with the valve chamber of the
valve. Thus, the valve stem will be in a balanced condition during
operation or will be subjected to designed resultant force loading
to permit ease of actuation. Moreover, the valve may be actuated
between the open and closed positions thereof exclusive of the
actuating mechanisms simply by manipulating the hand wheel to
induce rotatable movement to the actuating stem 392.
While FIGS. 12 and 13 illustrate valve actuator structures
incorporating both a fluid energized actuating mechanism and a
manual actuating mechanism, it is intended that only one of these
mechanisms be capable of actuation without minor alteration. This
feature allows the actuating mechanism to be readily changed from
one actuating mode to another simply and quickly in the field
without complete overhaul of the actuator.
As shown in FIGS. 15 and 16, both of the modifications are adapted
for manual actuation. Movement of the valve stem may be achieved
simply by rotating the hand wheel and actuating stem in each case
to impart partial movement to the valve stem. The piston actuator
in each case is inoperative because the actuator stem is restrained
against vertical movement by the cooperating thrust bearings 330
and 332 as shown in FIG. 12 for example, which restrain the annular
shoulder 328 against vertical movement.
If it is desired to convert the actuating mechanism to fluid
actuation, this can be accomplished simply by removing the retainer
334 which allows the upper bearing 330 to be removed. The annular
shouler element then may be removed simply by removing the upper
snap ring element that secures it in assembly with the actuating
stem 344. The lower thrust bearing may be easily removed after the
annular shoulder 328 has been disassembled from the actuator
stem.
The thrust flange 394 and the thrust bearings 396 and 398
illustrated in FIG. 13 may be removed to allow fluid actuation of
the actuating mechanism simply by unthreading the retainer element
from the actuator housing and by removing the upper snap ring that
secures the thrust flange 395 in assembly with the actuator
stem.
It is obvious that the pressure balancing concept of the present
invention will function equally well when incorporated with a valve
and hydraulic or pneumatic actuator assembly. The pressure
balancing concept of the present invention does not in any way
interfere with a manual override system with which a rising stem
type gate valve may be provided. The invention effectively provides
a valve and actuator assembly having a manual override mechanism to
operate the valve exclusive of the pneumatic or hydraulic actuator
system. The invention further incorporates a mechanism for
selectively deactivating the actuator mechanism to allow personnel
to safely service or repair a flow system controlled by the valve
and actuator assembly. The invention therefore effectively achieves
all of the objects hereinabove set forth together with other
objects and advantages that are inherent from a description of the
apparatus itself. While the above description has referred to
particular embodiments of the invention, it is to be understood
that the subject apparatus may also be incorporated into other
structures without departing from the spirit or scope of this
invention. It is to be further understood that the embodiments
described and illustrated herein are merely illustrative of an
application of the principles of the invention and that numerous
other arrangements and modifications may be made in the structures
illustrated without departing from the spirit and scope of this
invention.
* * * * *