U.S. patent application number 13/785592 was filed with the patent office on 2014-04-17 for actuator with dual drive.
This patent application is currently assigned to SWAGELOK COMPANY. The applicant listed for this patent is SWAGELOK COMPANY. Invention is credited to William H. Glime, III, Branden W. Keeper.
Application Number | 20140103240 13/785592 |
Document ID | / |
Family ID | 50474553 |
Filed Date | 2014-04-17 |
United States Patent
Application |
20140103240 |
Kind Code |
A1 |
Glime, III; William H. ; et
al. |
April 17, 2014 |
ACTUATOR WITH DUAL DRIVE
Abstract
A manually operated actuator is provided with an over-travel
feature. The over-travel feature may be realized with a controlled
thread backlash or with a biasing member such as a Belleville
spring. When used with a flow control device such as a diaphragm
valve, the over-travel feature allows the valve to open and close
at actuator positions other than full stop positions. Embodiments
for manual actuators and hybrid actuators are presented.
Inventors: |
Glime, III; William H.;
(Chagrin Falls, OH) ; Keeper; Branden W.; (Mentor,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SWAGELOK COMPANY |
Solon |
OH |
US |
|
|
Assignee: |
SWAGELOK COMPANY
Solon
OH
|
Family ID: |
50474553 |
Appl. No.: |
13/785592 |
Filed: |
March 5, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61714831 |
Oct 17, 2012 |
|
|
|
Current U.S.
Class: |
251/265 ;
251/272 |
Current CPC
Class: |
F16K 31/506 20130101;
F16K 7/14 20130101; F16K 1/04 20130101; F16K 31/50 20130101; F16K
31/143 20130101; F16K 7/16 20130101; F16K 31/52408 20130101; F16K
35/022 20130101 |
Class at
Publication: |
251/265 ;
251/272 |
International
Class: |
F16K 31/50 20060101
F16K031/50; F16K 31/524 20060101 F16K031/524 |
Claims
1. An actuator comprising an actuator stem that is moveable between
a first position and a second position, an actuator drive member
coupled to said actuator stem to move said actuator stem between
said first position and said second position, a biasing member that
applies a first force on said actuator stem when said actuator stem
is in said first position, said actuator drive member applies a
second force on said actuator stem when said actuator stem is in
said second position.
2. The actuator of claim 1 wherein said actuator stem comprises a
first portion and a second portion, and a coupling between said
first portion and said second portion, said coupling transfers said
first force from said biasing member to said first portion of said
actuator stem when said actuator stem is in said first
position.
3. The actuator of claim 2 wherein said coupling transfers said
second force from said actuator drive member to said second portion
of said actuator stem when said actuator stem is in said second
position.
4. The actuator stem of claim 3 wherein said actuator drive member
provides a direct drive to said second portion of said actuator
stem when said actuator stem is in said second position.
5. The actuator of claim 1 wherein said actuator drive member
comprises a handle that is rotatable about an axis.
6. The actuator of claim 1 in combination with a valve that is
operated by movement of said actuator stem.
7. The actuator of claim 6 wherein said valve comprises a diaphragm
valve.
8. The actuator of claim 6 comprising a pneumatic actuator that is
operable to open and close said valve.
9. The actuator of claim 8 wherein said actuator drive member can
be operated to override operation of said pneumatic actuator.
10. The actuator of claim 3 wherein said coupling comprises a
threaded connection between said biasing member and said first
portion of said actuator stem, said threaded connection comprising
a controlled thread backlash.
11. The actuator of claim 10 wherein said controlled thread
backlash causes an over-travel condition between said actuator
drive member and said actuator stem position.
12. The actuator of claim 1 wherein said biasing member causes an
over-travel condition between said actuator drive member and said
actuator stem position.
13. The actuator of claim 12 wherein said biasing member comprises
a biasing member.
14. The actuator of claim 1 wherein said actuator stem comprises a
first portion and a second portion, and a coupling between said
first portion and said second portion, said coupling comprising a
threaded connection between said biasing member and said first
portion, said threaded connection comprising a controlled thread
backlash.
15. The actuator of claim 14 wherein said controlled thread
backlash causes an over-travel condition between said actuator
drive member position and said actuator stem position.
16. The actuator of claim 14 in combination with a valve that is
operated by movement of said actuator stem.
17. An assembly of a valve and an actuator that can be connected so
that the actuator controls operation of the valve, comprising: a
valve comprising a valve member having a valve open position and a
valve closed position, said actuator comprising an actuator stem
that is moveable between an actuator stem first position that
corresponds to said valve open position and an actuator stem second
position that corresponds to said valve closed position, an
actuator drive member coupled to said actuator stem to move said
actuator stem between said actuator stem first position and said
actuator stem second position, a biasing member that applies a
first force on said actuator stem when said actuator stem is in
said actuator stem first position, said actuator drive member
applies a second force on said actuator stem when said actuator
stem is in said actuator stem second position.
18. The assembly of claim 17 wherein said actuator stem is moveable
to a third position that provides an over-travel from said valve
closed position.
19. The assembly of claim 18 wherein said actuator stem is moveable
to a fourth position that provides an over-travel from said valve
open position.
20. The assembly of claim 17 wherein said actuator stem comprises a
first portion and a second portion, and a coupling between said
first portion and said second portion, said coupling comprising a
threaded connection between said biasing member and said first
portion, said threaded connection comprising a controlled thread
backlash.
21. The assembly of claim 17 wherein said biasing member causes an
over-travel condition between said actuator drive member and said
actuator stem position.
22. The assembly of claim 21 wherein said biasing member comprises
a spring.
23. The assembly of claim 17 wherein said valve comprises a
diaphragm valve.
24. The assembly of claim 17 wherein said actuator comprises a
pneumatic actuator that is operable to move said valve member
between said valve open position and said valve closed
position.
25. The assembly of claim 24 wherein said actuator drive member is
manually operable and can be used to override operation of said
pneumatic actuator.
26. The actuator of claim 2 wherein said second portion of said
actuator stem is threadably coupled to an actuator housing and said
coupling provides a threaded connection between said first portion
of said actuator stem and said second portion of said actuator
stem.
27. The actuator of claim 26 wherein said second portion of said
actuator stem is threadably coupled to the actuator housing with a
first thread orientation and said coupling comprises a thread
orientation that is opposite said first thread orientation.
28. The actuator of claim 20 wherein said second portion of said
actuator stem is threadably coupled to an actuator housing and said
coupling provides a threaded connection between said first portion
of said actuator stem and said second portion of said actuator
stem.
29. The actuator of claim 28 wherein said second portion of said
actuator stem is threadably coupled to the actuator housing with a
first thread orientation and said coupling comprises a thread
orientation that is opposite said first thread orientation.
30. An actuator and valve assembly comprising: a valve comprising a
valve member that can be moved in an axial direction, an actuator
comprising an actuator stem and an actuator drive member, said
actuator drive member being manually operable with said actuator
stem to move said valve member, a dual drive coupling for said
actuator drive member and said actuator stem that provides greater
axial stroke of said actuator stem as compared with axial stroke of
said actuator stem without said dual drive coupling.
31. The assembly of claim 30 wherein said dual drive coupling
comprises a first threaded connection and a second threaded
connection, said first threaded connection comprising a first
thread orientation and said second threaded connection comprising a
second thread orientation that is opposite said first thread
orientation.
32. An actuator comprising an actuator stem that is moveable
between a first position and a second position, said actuator stem
comprising a first portion and a second portion, an actuator drive
member coupled to said actuator stem to move said actuator stem
between said first position and said second position, a threaded
coupling between said actuator stem first portion and said actuator
stem second portion, said threaded coupling comprising a controlled
thread backlash.
33. The actuator of claim 32 in combination with a flow control
device having open and closed positions, wherein said controlled
thread backlash provides axial over-travel for one or both of said
valve open and closed positions.
Description
RELATED APPLICATION
[0001] This application claims the benefit of pending U.S.
Provisional Patent Application Ser. No. 61/714,831 filed on Oct.
17, 2012 for ACTUATOR WITH OVER-TRAVEL, the entire disclosure of
which is fully incorporated herein by reference.
BACKGROUND OF THE DISCLOSURE
[0002] The inventions relate to actuators for flow control valves
and other devices. The inventions more particularly relate to
manually operated actuators and also hybrid actuators that may be
manually operated and/or pneumatically operated.
[0003] Actuators may be used for many different functions and
operations. One example is to open and close a valve or other flow
control device. Actuators may operate in many different ways. One
example is a manually operated actuator in which an actuator drive
member, for example a handle, can be manually moved between two
positions. Other actuators may be pneumatically operated thereby
allowing automatic, remote, or electronic control of the actuator
operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 illustrates an isometric view of an embodiment of
manually operated actuator and valve assembly and in a fully closed
position.
[0005] FIG. 2 is the actuator and valve assembly of FIG. 1 in
longitudinal cross-section.
[0006] FIG. 3 is the actuator and valve assembly of FIG. 1 in
longitudinal cross-section and in a fully open position,
[0007] FIG. 3A is an exemplary plot of an over-travel concept that
may be realized with the teachings herein,
[0008] FIGS. 4A-4D illustrate in a simplified schematic manner an
embodiment of a coupling having a controlled thread backlash for an
over-travel feature of the embodiment of FIG. 1,
[0009] FIG. 5 is an embodiment of a hybrid actuator and valve
assembly in isometric and in a valve closed condition,
[0010] FIG. 6 is the hybrid actuator and valve assembly of FIG. 5
in longitudinal cross-section,
[0011] FIG. 7 is another embodiment of a dual drive manual actuator
and valve assembly with over-travel,
[0012] FIG. 8 is another embodiment of a dual drive manual actuator
and valve assembly with over-travel,
[0013] FIG. 9 is another embodiment of a manual actuator and valve
assembly.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0014] By way of introduction, this disclosure presents a number of
embodiments that illustrate several inventive concepts relating to
an actuator. One inventive concept is embodied in a manually
operated actuator that has a dual drive structure for the actuator
stem. The dual drive structure provides increased stroke of the
actuator stem without increasing actuation torque needed to reach a
closed position.
[0015] Another inventive concept may be embodied in a manually
operated actuator that has a dual drive structure for an actuator
stem that applies a first force to the actuator stem using an
indirect drive, for example with a biasing member, and applies a
second force to the actuator stem using a direct drive between an
actuator drive member and the actuator stem, for example with a
threaded connection.
[0016] Another inventive concept may be embodied in a manually
operated actuator that has a dual drive structure for an actuator
stem wherein the actuator stem includes a first portion and a
second portion, and a coupling between the first portion and the
second portion. In one embodiment the coupling may be realized in
the form of a threaded coupling having a controlled or designed-in
thread backlash.
[0017] Another inventive concept may be embodied in an actuator
that is used to control operation of a flow control device such as,
for example, a valve. In one embodiment, a dual drive structure for
an actuator stem is provided. In another embodiment, the dual drive
structure includes an actuator stem having a coupling that provides
axial over-travel.
[0018] Another inventive concept may be embodied in an actuator
that is used to control operation of a flow control device such as,
for example, a valve. In one embodiment, the actuator may include
an over-travel mechanism that provides, for example, axial
over-travel of the actuator relative to the open or closed state of
the valve or both. In a more particular embodiment, the over-travel
mechanism may include a controlled or designed-in thread backlash
to provide the over-travel. In another embodiment, the over-travel
mechanism may include a biasing member that provides the
over-travel, alternatively with or without including a coupling
having a controlled or designed-in thread backlash.
[0019] Another inventive concept may be embodied in a hybrid
actuator that is used to control operation of a flow control device
such as, for example, a valve. In one embodiment, the hybrid
actuator may include a pneumatically operated actuator stem that
incorporates a manual override that disables and enables the
pneumatic actuator. In another embodiment, the manual actuator
portion of the hybrid actuator may be realized using any of the
above inventive concepts and embodiments.
[0020] Additional alternative and optional embodiments of
structure, features and operation of these inventive concepts and
embodiments are presented hereinbelow. The inventions may also be
used for applications for controlling a valve and actuator using
other configurations than the embodiments described herein, and
valve and actuator designs other than the exemplary designs shown
herein. The inventions may also find application and use with
devices other than valves and flow control devices.
[0021] With reference to FIGS. 1-3, an actuator and valve assembly
10 may include an actuator assembly 12 and a flow control device
such as, for example, a valve assembly 14. The actuator assembly
may be realized in the form of a manually operated actuator. The
valve assembly 14 may have many different configurations and uses.
The valve assembly 14 may be realized in the form of a diaphragm
valve having a valve body 16 that has two or more flow passages
therein so as to control the flow of fluid, for example a liquid or
gas, from one port to another. In the view of FIGS. 1 and 2, an
inlet flow passage 18 (which is hidden in the orientation of FIG.
2) opens to an inlet port 20. An outlet port 22 opens to an outlet
flow passage 24. Both the inlet flow passage 18 and the outlet flow
passage 24 communicate with a valve cavity 26. The valve cavity 26
opens to the outlet flow passage 18 through an annular valve seat
28. A valve member 30, for example a diaphragm 30, seals the valve
cavity 26 from the actuator assembly 12. The diaphragm 30 is moved
toward and into contact with the valve seat 28 to close the valve
(FIG. 2) and is moved away from the valve seat 28 to open the valve
(FIG. 3). The diaphragm 30 movement is effected by operation of the
actuator assembly 12.
[0022] Operation of a diaphragm valve as described is well known
and need not be further described herein to understand and practice
the inventions, nor does the flow control device need to be a
diaphragm valve for it should be noted that many other types of
valves may be used other than a diaphragm valve, for example, a
bellows valve or plug type shutoff valve to name just two examples.
The valve assembly 14 may alternatively include additional ports
and flow passages, for example, a three way valve, and flow may
alternatively be bi-directional. The valve assembly 14
configuration as illustrated is what is known in the art as a
surface mount configuration, meaning that the inlet and outlet
ports 20, 22 are coplanar and the valve assembly is mounted to a
support surface such as a substrate of a gas stick. But this is but
one configuration, and the inventions may be used with flow control
devices that are connected in a fluid circuit in many different
ways, including but not limited to customary inlet and outlet end
connections, all of which are well known to those skilled in the
art.
[0023] The actuator assembly 12 may include an actuator housing 13
that receives an actuator drive member 32. Because this is a
manually operated actuator, the actuator drive member 32 may be
realized in the form of a handle 32 that can be manually operated.
However, a tool could optionally be used manually to operate the
handle 32. The handle 32 is coupled to an actuator stem 34 by any
convenient technique so that actuation of the handle 32 causes
linear movement of the actuator stem 34 along a longitudinal axis
X. For example, we show a spline connection 36 between the handle
32 and an upper end 34a of the actuator stem 34, but alternative
connections may be used. A bolt 38 may be used to secure the handle
32 with the actuator stem 34. The handle 32 therefore is adapted to
be manually rotated about the longitudinal axis X.
[0024] The actuator stem 34 may be realized in the form of a two
piece actuator stem 34. For example, there may be a first or lower
portion 40 of the actuator stem 34 and a second or upper portion 42
of the actuator stem 34. A first threaded connection 44 is provided
between an outer threaded portion of the second or upper portion 42
of the actuator stem 34 and an inner threaded portion of the
actuator housing 13. A coupling 46 joins the first portion 40 of
the actuator stem 34 and the second portion 42 of the actuator stem
34. The coupling 46 may be realized, for example, in the form of a
second threaded connection 48.
[0025] A biasing member 50 is disposed between a shoulder 52 of the
actuator housing 13 and a surface 54 of the first portion 40 of the
actuator stem 34. The biasing member 50 may be realized in many
different ways, in this example, the biasing member 50 is realized
in the form of a coiled spring. The biasing member 50 is compressed
in position so that the biasing member 50 urges the first portion
40 of the actuator stem 34 downward (as viewed in the figures) or
in other words towards the diaphragm 30.
[0026] An anti-rotation device 56 may be provided that prevents the
lower portion 40 of the actuator stem 34 from rotating about the X
axis, for reasons that will be described below. The anti-rotation
device 56 allows for axial translation of the lower portion 40. The
anti-rotation device 56 may be a pin that engages a flat exterior
surface 40a of the lower portion 40 of the actuator stem 34. Many
other techniques may be alternatively used to prevent rotation of
the actuator stem first portion 40.
[0027] An optional vent passage 59 may be provided between the
valve chamber 56 and the ambient environment. This vent allows
process fluid to exit the valve assembly in the event of a breach
of the diaphragm seal so that the process fluid does not enter the
actuator assembly.
[0028] The lower portion 40 of the actuator stem 34 may contact a
button 58 that in turn contacts an upper non-wetted surface of the
diaphragm 30. In this manner, axial translation of the actuator
stem 34 along with the action of biasing member 50 operates to open
and close the valve by moving the diaphragm 30 away from and
towards the valve seat 28.
[0029] For many manually operated flow control devices, for
example, a diaphragm valve as illustrated herein, the stroke of the
actuator stem that can be effected by the actuator assembly is
important so that the valve can fully open to achieve maximum flow.
But for a given actuator size that uses direct drive between the
actuator drive member and the actuator stem, increasing the
actuator stroke for a given amount of handle rotation also
increases the actuation torque. By direct drive we mean axial
translation of movement of the actuator stem 34 caused by operation
of the actuator drive member 32. For example, rotation of the
handle 32 applies a force on the actuator stem which directly
causes axial movement of the actuator stem 34 to open and close the
valve. The torque increases because in order to increase stroke of
the actuator stem for a defined degree of handle rotation in a
direct drive actuator, the thread pitch or other mechanical means
of translating rotational motion into linear travel must be
adjusted to provide more travel per degree of rotation, which
increases torque when the forces that the linear travel is acting
upon are similar. It is noted that the actuator and valve assembly
10 in this embodiment is a quarter turn valve, meaning that the
handle 32 only turns through ninety degrees from fully open to
fully closed positions of the valve.
[0030] We compensate for this torque versus stroke relationship by
incorporating an actuator assembly 12 that uses a dual drive
concept. The dual drive concept may be embodied using two drive
elements or portions that are coupled together but that become
operably disengaged with respect to each other at an applied load,
for example, an applied load that is defined or set by a biasing
member. By operably disengaged we are referring to disengagement of
the functional coupling or operation by which the dual drive first
portion and second portion provide axial displacement relative to
rotation of an actuator drive member. The dual drive concept may be
realized, for example, with the use of a dual drive coupling for
the actuator drive member 32 and the actuator stem 34. As noted
above, the actuator stem 34 has a first portion 40 and a second
portion 42 that are coupled together with the coupling 46. An
embodiment of a dual drive coupling for the actuator drive member
32 and the actuator stem 34 may be realized with the first threaded
connection 44 and the second threaded connection 48. More
particularly, we provide the first threaded connection 44 with a
first thread orientation, for example a right hand thread, and the
second threaded connection 48 with an opposite thread orientation,
for example a left hand thread. Alternatively, the first threaded
connection 44 may have a left hand thread orientation, and the
second threaded connection 48 may have a right hand thread
orientation.
[0031] Assume that the actuator assembly 12 is in the fully up
position as in FIG. 1 which corresponds to the valve being fully
open. When the actuator drive member or handle 32 is rotated
clockwise, the actuator stem upper portion 42 moves downward by
operation of the first threaded connection 44. Because the lower
portion 40 is coupled to the upper portion 42 using an opposite
hand thread orientation, and further because the lower portion 40
is prevented from rotating by the anti-rotation device 56, the
lower portion 40 also moves or strokes downward towards the
diaphragm. The total stroke of the actuator stem 34 is the combined
stroke of the upper portion 42 and the lower portion 40 of the
actuator stem 34. This is the case until the diaphragm 30 contacts
the valve seat 28. At that point, the valve is closed and the lower
portion 40 of the actuator stem 34 can no longer move axially
(disregarding some slight movement due to compression of the valve
seat 28).
[0032] After the diaphragm 30 makes contact with the valve seat 28,
the total stroke of the actuator stem 34 is basically equal to the
stroke of the upper portion 42 of the actuator stem 34. We thus
achieve an increase in overall stroke of the actuator between the
open and closed positions of the valve member 30 without increasing
thread pitch. Note that although the thread pitch has not been
increased, the handle torque needed to advance the stem against a
given load is similar to that of a single drive member having a
thread pitch that provides a comparable linear displacement or
stroke per degree rotation as compared to the combined or coupled
dual drive portions. Viewed another way, we have increased overall
stroke without increasing thread pitch, with the handle torque that
is needed to close the valve being the same as in a direct drive
actuator. In essence, we duplicate the effect of an increased
thread pitch using a single threaded drive mechanism by using
multiple threaded mechanisms with lower thread pitch members
operating in series. It is only during the portion of actuation
where the application of high closing force against the valve seat
is desired that we design the actuator so that the lower portion
disengages from the upper portion to enable direct drive of the
handle to close the valve.
[0033] In some applications, it may be desirable to provide an
over-travel feature for the actuator and valve assembly 10. By
over-travel we mean that the valve member 30 engages the valve seat
28 to close the valve before the full closing rotation of the
actuator drive member 32 is completed. This we refer to as closing
over-travel. Likewise, in some applications, it may be desirable
that the valve member 30 unseat from the valve seat 28 and allow
the valve to open fully before the full opening rotation of the
actuator drive member 32 is completed. This we refer to as opening
over-travel. This can be thought of as follows. The actuator 12
will have a first position of the actuator drive member 32 that is
at a first maximum position that corresponds to a valve open
condition. For example, in the case of a rotary actuator drive
mechanism such as the handle 32 embodiment of FIGS. 2 and 3, the
handle 32 would be turned fully counterclockwise to a first or
fully open stop position which we will reference as the 0.degree.
position (assuming a right hand thread orientation for the first
threaded connection 44). The actuator 12 will also have a second
position of the actuator drive member 32 that is at a second
maximum position that corresponds to a valve closed condition. For
example, in the case of a rotary actuator drive mechanism such as
the handle 32 embodiment, the handle 32 would be turned fully
clockwise to a second or fully closed stop position which will be
the 90.degree. position for a quarter turn actuator and valve
assembly 10. An opening over-travel feature means that the valve
member 30 releases from the valve seat 28 and allows the valve to
be open to its preferably full flow capacity before the actuator
drive member 32 reaches the 0.degree. position. A closing
over-travel feature means that the valve member 30 contacts the
valve seat 28 to block fluid flow through the valve before the
actuator drive member 32 reaches the 90.degree. position.
[0034] As an example, a 20.degree. over-travel for both opening and
closing positions of the actuator drive member 32 would mean that
the valve member 30 engages the valve seat 28 to close the valve
(although perhaps not seated with maximum closing force) when the
actuator drive member 32 has been rotated to a third position or
the 70.degree. position, and that the valve member 30 releases or
disengages from the valve seat 28 to open the valve (though not
fully opened) when the actuator drive member 32 has been rotated to
a position between the 70.degree. position and the 20.degree.
position. At and below the 20.degree. rotation position the valve
is fully open, for example. Alternatively, the function achieved at
these positions may be reversed if so desired. For example, the
actuator assembly 12 can easily be adapted so that the valve member
30 engages the valve seat 28 to close the valve (although perhaps
not seated with maximum closing force) when the actuator drive
member 32 has been rotated to a fourth position or the 20.degree.
position, and that the valve member 30 releases or disengages from
the valve seat 28 to open fully the valve when the actuator drive
member 32 has been rotated to the 70.degree. position, whereat the
fully open manual handle stop position being the 90.degree.
position and the fully closed manual handle stop position being the
0.degree. position. Moreover, the various degrees of rotation in
these examples are exemplary and not restrictive. For example, the
over-travel feature can be set at any desired angle of rotation by
adjustment of the structure used to achieve over-travel, such as
the exemplary structures described below or others. Note that for
each of the four positions described above, there is a
corresponding axial position of the actuator stem 34.
[0035] FIG. 3A illustrates an example of the over-travel concept
that may be realized using the teachings herein. This plot shows
linear travel or stroke of an actuator stem 34 in relation to
rotation angle of the actuator drive member 32 such as the handle
32 (note that as the handle 32 is rotated from A through to D the
handle rotation is counterclockwise as would be conventional for a
manual valve, but such is not required and alternatively may be
clockwise rotation as will be appreciated by those skilled in the
art). The dashed line illustrates the actuator stem 34 travel and
the solid line represents the valve member 30 open/close status.
For a quarter turn actuator, for example, A may represent the full
90.degree. handle clockwise rotation or in other words the handle
is at the fully closed stop position. D then may represent the full
0.degree. handle counterclockwise rotation, or in other words the
handle is at the fully open stop position. But conceptually, the
letters A, B, C and D relate to any angle desired by the actuator
designer for a particular application.
[0036] For the 20.degree. over-travel example we disclose above, B
may represent the 20.degree. handle rotation position (as
referenced in this example from the handle fully clockwise rotation
closed position A). Between A and B the valve member 30 contacts
the valve seat 28 and the valve is closed. The dashed line between
A and B may have a small slope (exaggerated for clarity in FIG. 3A)
because of possible small axial movement of the actuator stem as
the valve seat compresses (as noted hereinabove). C may represent
the 70.degree. handle counterclockwise rotation position (as
referenced in this example from the handle fully closed position
A). Between C and D then, the valve member is not in contact with
the valve seat 28 and the valve is open to flow. Whether the valve
member 28 provides full flow at position C may be a design
selection. Between B and C the valve member 30 is in the transition
region as it moves further towards it maximum distance from the
valve seat 28.
[0037] The dual drive concept of our actuator may be used
beneficially to also facilitate implementing over-travel, either
for opening over-travel, closing over-travel or both, when
over-travel is optionally to be included in an actuator and valve
assembly. In one embodiment, we provide a predetermined or
controlled thread backlash in the second threaded connection 48. We
note that many threaded connections may exhibit undesired or
unintended backlash due to poor tolerance control for example. Such
backlash is not necessarily a problem depending on the application
of the threaded connection but threaded connections preferably have
little backlash if any. But we have discovered that we can achieve
over-travel by purposely designing-in a controlled or predetermined
thread backlash for the second threaded connection 48 and combining
that designed backlash with the biasing member 50. So by controlled
or predetermined thread backlash or designed-in thread backlash we
mean that we purposely provide a controlled gap within the threaded
connection in order to achieve over-travel. This is different,
therefore, from a thread backlash that is attributable to less than
optimal manufacturing processes or designs or otherwise not
controlled or intentionally introduced into a threaded
connection.
[0038] FIGS. 4A-4D schematically illustrate an embodiment of a
controlled or designed-in thread backlash to realize, for example,
a 20.degree. over-travel in the actuator and valve assembly 10.
These figures provide, as an example, an enlarged schematic
illustration of the coupling 46 and the associated second threaded
connection 48 embodiments. FIG. 4A represents the actuator stem 34
(and for each FIG. 4A-4D the actuator drive member 32) in the
0.degree. or fully open valve position; FIG. 4B represents the
actuator stem 34 in the range of 0.degree. to 70.degree. position
where at 70.degree. the valve member 30 contacts the valve seat 28
to close the valve; FIG. 4C represents the actuator stem 34 in the
transition range of 70.degree. to 90.degree. position where the
valve member 30 contacts the valve seat 28 to close the valve; and
FIG. 4D represents the actuator stem 34 in the 90.degree. or fully
closed valve position.
[0039] FIGS. 4A-4D somewhat exaggerate the designed-in thread
backlash for clarity. The left side threaded structure represents
the lower portion 40 of the actuator stem 34, and the right side
threaded structure represents the upper portion 42 of the actuator
stem 34. In this exemplary embodiment of a 20.degree. over-travel,
the threads 60 of the lower portion 40 mesh with the threads 62 of
the upper portion 42, but with a controlled or designed-in gap 64
(see FIG. 4C) between the respective crest portion 66 and root
portion 68 of the threads 60, 62. The controlled gap 64 provides a
controlled or designed-in controlled backlash for the second
threaded connection 48 in the coupling 46.
[0040] With reference also to FIG. 2, recall that a biasing member
50, such as a spring, applies a downward first force (74) on the
valve member 30 through the lower portion 40 of the actuator stem
34. With the controlled gap 64, a lower surface 70 of each thread
60 of the lower portion 40 of the actuator stem 34 contacts or
slides along an upper surface 72 of each thread 62 of the upper
portion 42 of the actuator stem 34. Because the biasing member 50
is applying a first motive force 74 on the lower portion 40, as the
actuator drive member 32 is turned clockwise from 0.degree. to
70.degree. the non-rotating lower portion of the actuator stem
moves axially towards the valve member 30 due to the thread
engagement. Because the first motive force 74 is exclusively
attributable to the biasing member 50 and not the actuator drive
member 32, we refer to this movement as an indirect drive of the
lower portion 40 of the actuator stem 34. At the 70.degree.
position for the actuator drive member 32, the valve member 30 or
diaphragm contacts the valve seat 28 which contact opposes further
axial translation of the lower portion 40 of the actuator stem 34.
Therefore, as the actuator drive member 32 is turned clockwise from
70.degree. to 90.degree. the rotating and axially translating upper
portion 42 of the actuator stem 34 continues to move toward the
valve member 30, and the non-rotating and axially stationary lower
portion 40 of the actuator stem is fixed in position. The
controlled gap 64 thereby results in the threads 60 and 62 going
through a transition portion from 70.degree. to 90.degree. of
rotation of the actuator stem 34 where the threads 60, 62 are not
in contact with each other (FIG. 4C) and the valve continues to be
held closed by the indirect drive of the first force 74 that is
being applied to the lower portion 40 of the actuator stem 34 by
the biasing member 50. In other words, from the 70.degree. position
to at or near the 90.degree. position, the force applied through
rotation of the actuator drive member 32 overcomes the applied load
that is defined or set by the biasing member 50 (the first force
74) so that the upper portion 42 of the actuator stem 34 disengages
from the lower portion 40 of the actuator stem 34.
[0041] At or near the 90.degree. position, the threads 60, 62
reengage, but now an upper surface 76 of each thread 60 of the
lower portion 40 of the actuator stem 34 contacts or slides along a
lower surface 78 of each thread 62 of the upper portion 42 of the
actuator stem 34. As a result, as the actuator stem 34 is rotated
to the fully closed 90.degree. position, the upper portion 42 of
the actuator stem 34 is directly applying a closing load or second
force 80 against the lower portion 42 of the actuator stem, which
second force is directly transmitted to the valve member 30 to
apply a closing load on the valve member 30. Because the second
force 80 is exclusively attributable to the force applied by
rotation of the actuator drive member 32 to the upper portion 42 of
the actuator stem 34, and this second force is directly transmitted
to the valve member 30 through the lower portion 40 of the actuator
stem 34, we refer to this movement as a direct drive of the lower
portion 40 of the actuator stem 34 as the actuator drive member 32
reaches the 90.degree. fully closed position. It will be
appreciated that the degree of over-travel can be controlled by
selecting the amount of controlled backlash between the threads 60,
62. The backlash can be controlled in many ways, including
selection and control of the diameter and pitch of the engaging
threads 60, 62.
[0042] The direct drive portion of the actuation can be used to
apply a desired closing force 80 or load as needed on the valve
member 30 to provide a tightly closed valve. Because the closing
force 80 is produced by the direct drive of the upper portion 42 of
the actuator stem 34, and more particularly the actuator stem 34 is
now acting as a single drive member, the torque needed to apply the
closing force is the same as when a single direct drive actuator is
used with the same thread pitch. Therefore, greater stroke for the
actuator can be realized without increasing the torque needed for
the closing force 80. Typically, the closing or second force 80
will be higher than the first force 74 applied by the biasing
member 50. For example, the indirect drive first force of biasing
member 50 may apply a load of seventy pounds on the valve member
30, whereas the direct drive second force of the actuator stem 34
might provide a closing load of one-hundred twenty pounds. These
values are of course all exemplary.
[0043] We note at this point that although the exemplary
embodiments illustrate use of a rotary actuator drive member 32,
such is not required in all applications. For example, the
over-travel feature using a controlled gap may be realized with a
lever type actuator drive member or other actuator drive member
design as needed to effect axial translation of the actuator stem
34.
[0044] With reference next to FIGS. 5 and 6, we illustrate an
embodiment of a hybrid actuator and valve assembly 90. A hybrid
actuator includes a manual actuator function and a pneumatic
actuator function. In simple terms, the hybrid actuator includes a
pneumatically operated actuator assembly 92 and a manually operated
actuator assembly 84 with the manually operated actuator 94 stacked
on top of the pneumatically operated actuator 92. The manually
operated actuator assembly 94 may be but need not be realized in a
similar manner and function as the manually operated actuator 12
described hereinabove, and the same reference numerals are used for
like elements. Thus, the manual actuator assembly 94 may operate
with the over-travel feature and the predetermined thread backlash
concept of the manually operated actuator of FIGS. 1-3 herein.
[0045] A pneumatic actuator assembly 92 commonly includes a piston
assembly 96 that is disposed in an actuator housing 98. As shown,
the actuator housing may be a multi-piece housing or alternatively
a single piece housing. In the exemplary embodiment, two pistons
96a and 96b may be used but alternatively a single piston actuator
may be used or more than two pistons may be used as needed. A
spring 100 is used to urge the piston assembly 96 in a first
direction that pushes the valve member 102 or diaphragm of the
valve assembly 104 into sealing engagement with a valve seat 106,
thereby providing a normally closed valve. The piston assembly 96
may include an actuator stem 108 that has an air passage 110
therethrough. The air passage 110 is in fluid communication with an
air inlet fitting (not shown), through a housing air passage 112,
that receives pressurized air from a pressurized air source (not
shown). The air passage 110 communicates with a piston chambers 114
via air passages 116 in the pistons 96a and 96b. When pressurized
air is supplied to the pneumatic actuator assembly 92, the air
pressure overcomes the spring 100 bias and moves the piston
assembly 96 against the spring 100 to a second position (not
shown), which allows the valve member 102 to move to an open
position away from the valve seat 106. When air pressure is
removed, the spring 100 returns the piston assembly 96 to the first
position (FIG. 1) and the valve is closed. O-rings 118 or other
suitable seals provide pressure containment for the actuator
pressurized air to move the piston assembly 96.
[0046] Although the manually operated actuator 94 may be basically
the same as described hereinabove, it will be noted that the lower
portion 40 of the actuator stem 34 may also provide the air passage
110 access for the pneumatically operated actuator 92. Note also
that the actuator housing 120 may be extended compared to the
manually operated actuator alone in order to accommodate a portion
of the pneumatically operated actuator 92. And rather than the
lower portion 40 of the actuator stem 34 engaging the valve member
102 or a button 58, the lower portion 40 may engage a Belleville
spring 122 that also contacts the piston assembly 96. The
Belleville spring 122 may be used to provide the biasing force that
for the manual actuator of FIG. 2 is provided by the spring 50.
Thus, the manually operated actuator 94 may be used manually to
override the pneumatically operated actuator 92. For example, when
the manual actuator 94 is closed it prevents the pneumatic actuator
92 from opening the valve member 102 even if pressurized air is
applied to the housing air passage 112. In the event the pneumatic
actuator 92 is energized and the valve member 102 is in the open
position, the manual actuator 94 may be used to force the pneumatic
actuator 92 to the closed position when the actuator drive member
or handle 32 is rotated to the closed position. In the exemplary
embodiment, the manual actuator 94 cannot open the valve unless the
pneumatic actuator 92 is also energized to allow the open
condition.
[0047] FIGS. 7 and 8 illustrate additional alternative embodiments
for a manually operated actuator. In FIG. 7 we illustrate an
embodiment of a dual drive actuator 130 that uses a biasing member
132, such as a Belleville spring. In this embodiment, the
Belleville spring 132 may be pre-compressed so that the Belleville
spring 132 will go to a flat condition in a predetermined stroke of
the upper portion 134 of the actuator stem 136 relative to a lower
portion 138 of the actuator stem 136 after the valve member (150)
contacts the valve seat (154). A first threaded connection 140
joins the upper portion 134 to the housing 142 and a second
threaded connection 144 joins the lower portion 138 to a threaded
nut 146. Note in this example that the actuator stem 136 is a
single piece stem because of the alternative use of the threaded
nut 146. As in the first embodiment, the first and second threaded
connections 140, 144 may have different thread orientations. For
example, the first threaded connection 140 may have a right hand
thread orientation and the second threaded connection 144 may have
a left hand thread orientation. The Belleville spring 132 is used
to provide the over-travel feature, so that the second threaded
connection 144 need not include a design-in thread backlash,
although alternatively it may as needed. The lower portion 138 may
directly contact a button 148 or a valve member 150 such as a
diaphragm, or may make the contact to the valve member 150 using an
intermediate piece 152. In this example, the intermediate piece 152
serves to pre-compress the spring 132 in cooperation with the
threaded nut 146.
[0048] FIG. 7 shows the assembly in a valve open position. As the
handle 148 is turned clockwise, the upper portion 134 moves
downward as does the lower portion 138 of the actuator stem 136
under the influence of the pre-compressed Belleville spring 132,
which applies a first force to the valve member 150. When the valve
member 150 contacts the valve seat 154, further axial movement of
the upper portion 134 will cause the Belleville spring 132 to go to
a flat condition so that the upper portion 134 now provides a
direct drive to apply a second force to the valve member 150. The
amount of stroke that is designed into the Belleville
pre-compression before the spring 132 goes to a flat condition can
be used to control the amount of over-travel.
[0049] FIG. 8 illustrates a direct drive manually operated actuator
160 that includes an over-travel feature. The over-travel feature
may be realized in the form of a Belleville spring or other biasing
member 162 as needed. The Belleville spring may be pre-compressed
as in the embodiment of FIG. 7 so that the amount of stroke that is
designed into the Belleville spring pre-compression before the
Belleville spring 162 goes to a flat condition can be used to
control the amount of over-travel. In the embodiment of FIG. 8, the
actuator 160 is conventional in design to provide a direct drive
between an actuator stem 164 and the valve member 166, with an
optional button 168. However, in this embodiment, the biasing
member 162 may be disposed between the actuator stem 164 and the
valve member 166 or optional button 168. As the direct drive
actuator stem 164 moves axially toward the valve member 166, a
first force is applied to the valve member 166 by operation of the
pre-compressed biasing member 162. When the valve member 162
contacts the valve seat 170, there will be a predetermined stroke
before the pre-compressed Belleville spring or biasing member 162
goes to a flat condition. This stroke provides the over-travel
feature. After the Belleville spring goes to a flat condition, the
direct drive of the actuator stem 164 applies a second closing
force to the valve member 166 against the valve seat 170. Note that
since this is a direct drive manually operated embodiment, there is
only a single threaded connection 172 for the actuator stem
164.
[0050] FIG. 9 illustrates an alternative embodiment of the manual
actuator of FIGS. 1-3 above. The manual actuator and valve assembly
200 may operate in substantially the same manner as the embodiment
of FIGS. 1-3, therefore, such description need not be repeated. We
use similar reference numerals for like parts but beginning with
the 200 series. Thus, 244 corresponds to the first threaded
connection 44 in FIG. 2. The assembly 200 in FIG. 9 is illustrated
in the valve closed position, and the assembly 200 is rotated
ninety degrees from the view of FIG. 2.
[0051] By comparing FIG. 2 with FIG. 9, we have replaced an inner
shoulder that present the surface 52 with a retaining ring 252
against which the spring 250 presses. The anti-rotation device 56
(FIG. 2) has been replaced with a broached hex 256 geometry for the
second or lower portion 240 of the actuator stem 234. The broached
hex 256 is received in a hex-shaped flange 257 of the actuator
housing 213.
[0052] While various aspects and features and concepts of the
inventions are described and illustrated herein as embodied in
various combinations in the exemplary embodiments, these various
aspects, features and concepts may be realized in many alternative
embodiments, either individually or in various combinations and
sub-combinations thereof. Unless expressly excluded herein all such
combinations and sub-combinations are intended to be within the
scope of the present invention. Still further, while various
alternative embodiments as to the various aspects and features of
the invention, such as alternative materials, structures,
configurations, methods, devices and so on may be described herein,
such descriptions are not intended to be a complete or exhaustive
list of available alternative embodiments, whether presently known
or later developed. Those skilled in the art may readily adopt one
or more of the aspects, concepts or features of the various
inventions into additional embodiments within the scope of the
present inventions, even if such embodiments are not expressly
disclosed herein. Additionally, even though some features, concepts
or aspects of the inventions may be described herein as being a
preferred arrangement or method, such description is not intended
to suggest that such feature is required or necessary unless
expressly so stated. Still further, exemplary or representative
values and ranges may be included to assist in understanding the
present inventions however, such values and ranges are not to be
construed in a limiting sense and are intended to be critical
values or ranges only if so expressly stated. Additionally, even
though some features and aspects and combinations thereof may be
described or illustrated herein as having a specific form, fit,
function, arrangement or method, such description is not intended
to suggest that such descriptions or illustrated arrangements are
required or necessary unless so expressly stated. Those skilled in
the art will readily appreciate additional and alternative form,
function, arrangement or methods that are either known or later
developed as substitute or alternatives for the embodiments and
inventions described herein.
[0053] The inventions have been described with reference to the
exemplary embodiments. Modifications and alterations will occur to
others upon a reading and understanding of this specification and
drawings. It is intended to include all such modifications and
alterations insofar as they come within the scope of the appended
claims or the equivalents thereof.
* * * * *