Fluid handling – With indicator – register – recorder – alarm or inspection means – Position or extent of motion indicator
Reexamination Certificate
2002-04-19
2004-06-01
Rivell, John (Department: 3753)
Fluid handling
With indicator, register, recorder, alarm or inspection means
Position or extent of motion indicator
C552S553000
Reexamination Certificate
active
06742541
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to valve indicators, and more particularly to a valve indicator for visually and/or electronically indicating the position of a valve shaft.
BACKGROUND OF THE INVENTION
Various electrical and mechanical position indicators are used to indicate the position of pneumatic or hydraulic lift valves. Switches are activated in respective end positions of the valve stroke, creating an electrical signal for open and closed-valve positions. The signal can then be transmitted to a control unit. Similarly, visual indication can also be provided to display the open and closed positions of the valve.
FIGS. 1A-1C
illustrate some of the electrical and/or visual solutions for providing linear position indication for a valve.
FIG. 1A
illustrates a principle used in the art for providing electrical indication of the position of a valve stem. The valve stem
10
has an adapter
12
attached. The adapter
12
activates a first switch
20
when the valve stem
10
is at a position where the valve is closed. The first switch
20
is adjustable along a fixed shaft
22
. Thus, moving switch
20
along the shaft
22
changes the position for indicating a closed-valve. A shaded area
24
represents the area in which a closed-valve position can be adjusted.
The adapter
12
activates a second switch
30
when the valve stem
10
is at an open position. The second switch
30
also adjustable along a fixed shaft
32
. Thus, moving the switch
30
along the shaft
32
changes the position for indicating an open-valve. A shaded area
34
indicates the area in which the open-valve position can be adjusted and the switch
30
is triggered. With the present arrangement, however, providing visual indication for the position of valves with various stroke lengths is not readily evident.
FIG. 1B
illustrates another principle used in the art for providing indication of the position of a valve. Referring to the schematic diagram of
FIG. 1B
, the apparatus for monitoring valve lift has two adjusters
14
and
16
, which activate two limit switches
20
and
30
, respectively. The switches
20
,
30
act as position sensors for the up and down positions of a drive spindle
12
. The present arrangement allows for the adjusters
14
and
16
to be moved so that they activate the limit switches
20
,
30
in the open and closed positions for a given valve stroke.
The drive spindle
12
has the same stroke length as the valve stem
10
. Hence, the arrangement does not readily offer a solution to provide a visual indicator among valves having different stroke lengths. The visual indicator
40
would have the same display length
42
as the stroke length
18
of the valve stem
10
. Therefore, the visual indicator
40
would display different amounts of visual area for valves having different stroke lengths.
FIG. 1C
illustrates yet another principle used in the art for providing indication of the position of a valve. The valve stem
10
has an adapter
12
attached. An adjuster
14
activates a first switch
20
when the valve stem
10
is at a closed-valve position. The adjuster
14
is adjustable along adapter
12
. A shaded area
24
represents the area in which the closed-valve position can be adjusted and the switch
20
is triggered.
Another adjuster
16
activates a second switch
30
when the valve stem
10
is at an open-valve position. The adjuster
16
is adjustable along adapter
12
. Thus, moving the adjuster
16
along the adapter
12
changes the position for indicating an open-valve. A shaded area
34
represents the area in which the open-valve position can be adjusted and the switch
30
is triggered.
With the present arrangement, a visual indicator
40
for indicating the position of the valve would have an indication length
42
that is equal to the stroke length
18
minus the separation H between the two adjusters
14
,
16
. Thus, it is not clear how a single visual indicator could be adapted to the present arrangement for use on valves with various stroke lengths.
The present invention is directed to providing a visual and electrical indicator for valves with various lengths of valve strokes.
SUMMARY OF THE INVENTION
In view of the foregoing and other considerations, the present invention relates to an apparatus for visually and/or electronically indicating the position of a valve shaft.
In accordance with one aspect of the present invention, there is provided an apparatus for indicating a state of a valve. The valve has a stem being movable in closing and opening directions between closed and open valve positions. The apparatus includes a first cam system being biased in the opening direction. The first cam system is capable of adjustably engaging the stem when the stem is adjacent to the closed valve position and is movable by the stem in the closing direction once engaged. The apparatus also includes a second cam system being integral to or separate from the first cam system and being biased in the closing direction. The second cam system is capable of adjustably engaging the stem when the stem is adjacent to the open valve position. The second cam system is movable by the stem in the opening direction once engaged. The apparatus includes an indicator moveable by the first and the second cam systems. The indicator is capable of indicating at least open, intermediate, and closed states of the valve.
In accordance with another aspect of the present invention, there is provided an apparatus for visually and electronically indicating a state of a valve. The valve has a stem being movable in closing and opening directions between closed and open valve positions. The apparatus includes a first cam system, a first switch, a second cam system, a second switch, and an indicator. The first cam system includes a first adjustable member engaging the stem when the stem is adjacent to the closed valve position. The first cam system is movable by the stem in a closing direction once engaged. The first cam system also includes a first biasing member forcing the first cam system in the opening direction. The first switch is capable of being actuated by the first cam system when the stem is at the closed valve position. The second cam system is integral to or separate from the first cam system. The second cam system includes a second adjustable member engaging the stem when the stem is adjacent to the open valve position. The second cam system is movable by the stem in the opening direction once engaged. The second cam system also includes a second biasing member forcing the second cam system in the closing direction. The second switch is capable of being actuated by the second cam system when the stem is at the open valve position. The indicator is moveable by the first and the second cam systems and is capable of indicating at least open, intermediate, and closed states of the valve.
In accordance with yet another aspect of the present invention, there is provided a method for indicating states of a valve having a stem. The stem is movable in closing and opening directions between closed and open valve positions. The method includes the steps of: adjusting a first cam system to engage the stem adjacent the closed valve position and adjusting a second cam system to engage the stem adjacent the opened valve position. The method also includes indicating a closed-valve state by displacing the first cam system in the closing direction with the stem to the closed valve position and indicating an open-valve state by displacing the second cam system in the opening direction with the stem to the opened valve position. The method also includes indicating an intermediate-valve state in the absence of engagement of the stem with the first and second cam system by biasing the first cam system in the opening direction and biasing the second cam system in the closing direction.
The foregoing summary is not intended to summarize each potential embodiment, or every aspect of the invention disclosed herein, but merely to summarize the appended claims.
REFERENCE
ASCO Controls, LP
Howrey Simon Arnold & White , LLP
Rivell John
LandOfFree
Linear indicator for a valve does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Linear indicator for a valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear indicator for a valve will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3356779