Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2200131
Grease Injection System for a Gate Valve Stem
Background of the Invention
1. Field of the Invention
This invention relates to gate valves. More particularly, the invention
relates to a system for lubricating the stem which drives the gate of the gate
valve.
10 2. Description of Related Art
Frequently, manually operated large bore and high pressure gate
valves experience high friction between the stem threads and lift nut
threads. Lubrication serves to reduce this friction, thereby reducing the
operating torque by as much as 50%. After a few cycles of opening and
15 closing the valve, the grease or other lubricant becomes displaced. As the
friction increases between the stem threads and the gate lift nut threads
due to the displacement of lubricant, the operating torque likewise
increases. When this elevated operating torque becomes too great, the
operator needs a method for lubricating between the stem and gate lift nut
20 threads.
Presently, several methods exist for lubricating the threads, including:
(1) disassembling the valve, and (2) filling the valve body cavity with
lubricant in order to infuse lubricant into the stem relief hole where the stem
threads are located. Disassembly of the valve enables lubricant to be
25 placed directly on the stem and lift nut threads, but requires a breach of the
valve pressure system which renders the valve inoperable while
disassembled. Additionally, disassembly is a labor intensive, time
consuming procedure. The method of filling the body cavity with lubricant is
also ineffective. This method is neither labor intensive nor does it render
30 the valve inoperable; however, even with a great deal of lubricant being
placed into the valve body cavity, very little lubricant actually works its way
into the stem relief hole. Therefore, very little lubricant contacts the stem
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threads. Another disadvantage of this method is the potential for lubricant
to leak into the valve body cavity and mix with the fluid flowing in the valve
flow path.
Therefore, there is a need for a gate valve wherein lubricant may be
5 applied directly to the valve stem and gate lift nut threads without (1)
disassembling the gate valve body, or (2) filling the valve body cavity.
Summary of the Invention
According to one embodiment of the invention, there is provided a
gate valve with an improved lubricating means for reducing operating
10 torque, wherein the gate valve comprises a valve housing having a flow
passage therethrough adapted to mate between two open conduits in a flow
line so as to form a continuous closed flow path therewith; a valve gate that
is movably mounted in the valve housing and adapted to move into and out
of the flow path so as to create a stop flow and an open flow position,
15 respectively; a gate lift nut that has a threaded internal through hole and is
mounted to said valve gate; a rotatable valve stem that extends into the
valve housing such that a first end of the stem extends outside the housing
and is adapted to receive torque to effect rotation of the stem and a second
end of the stem has a threaded surface and is received within a lift nut
20 through hole, whereby rotation of the valve stem causes the lift nut and the
gate to translate along the stem moving the gate selectively into a stop flow
or open flow position; a lubricant reservoir; at least one distribution hole fordistributing lubricant to the threaded surface of the stem; and channel
means contained within the valve stem and in communication with the
25 reservoir and the distribution hole to distribute lubricant from the reservoir to
the threaded stem surface.
According to another embodiment of the invention, there is provided
an improved valve stem with a lubricating means for use in a gate valve of
the type comprising a threaded valve stem and gate lift nut assembly,
30 wherein the improved valve stem comprises a valve stem shaft having a
first end and a second end whereby the first end of the shaft is adapted to
received torque to effect rotation and the second end of the shaft has a
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threaded surface adapted to mate with and cooperate with a threaded
opening through a gate lift nut such that rotation of the valve stem relative
to the gate lift nut causes the lift nut to translate along the stem; at least
one lubricant distribution hole extending from the threaded surface of said
valve stem shaft to the interior of said valve stem shaft for distributing
lubricant to said threaded surface; and a channel means axially extending
through the valve stem shaft and in communication with the lubricant
distribution hole and a lubricant reservoir.
According to a further embodiment of the invention, there is provided
a gate valve comprising a stem having threads7 a lubricant reservoir, a hole
for distributing lubricant to the threads of said stem, and a channel that
connects the reservoir to the hole.
The present invention will be better understood by a reading of the
following detailed description, with reference to the attached drawings,
wherein like parts in each of the several figures are identified by the same
reference character.
Brief descriPtion of the Drawings
Fig. 1A is a cross-sectional schematic drawing of one embodiment of
the invention;
Fig. 1B is an enlarged detail of a portion of the invention depicted in
Fig. 1a;
Fig. 2 is a cross-sectional schematic drawing of another embodiment
of the invention;
Fig. 3 is a cross-sectional schematic drawing of a further
embodiment of the invention; and
Fig. 4 is a cross-sectional schematic drawing of a still further
embodiment of the invention.
Detailed Description of the Preferred Embodiments
Referring to Figs. 1A and 1B, an embodiment of a gate valve 1
according to the present invention is shown. The valve 1 comprises a stem
10 having threads 11, a layered coil-shaped washer 12, a lubricant
distribution channel or hole 13 for distributing lubricant to threads 11 of
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stem 10, and a channel or hole 14 that connects the washer 12 to the
distribution hole 13 via a transverse hole 8 that is positioned transverse to
the longitudinal central axis of the stem 10. Thus, lubricant flows from the
washer 12 through the transverse hole 8, through the longitudinal hole 14
5 and finally to the distribution hole 13. In this embodiment, the distribution
hole 13 is a hole that runs from the threaded surface 11 of the stem 10 to
the longitudinal hole 14. The layered coil-shaped washer 12 preferably has
a number of approximately 0.0625 inch thick coils which stretch around the
outside diameter of the stem backseat 20. In the embodiment shown, the
10 top four coils are notched to allow lubrication to travel into the transverse hole 8 and into the hole 14. With the gate 17 in the closed position,
lubricant is forced into the threads of the lift nut 18. With the gate 17 in theopen position, which is depicted in Fig. 1A, the lubricant fills the stem reliefhole 19 of gate 17, thereby forcing lubricant onto the stem threads 11. The
lower coils 15 of washer 12 restrict lubricant in washer 12 from entering the
valve body cavity 16. Coils 15 force the lubricant into the transverse hole 8
in the stem, instead of letting it pass into the valve body cavity 16. The
valve 1 also comprises an injection fitting 22 on the outside diameter of the
bonnet flange 21. Lubricant may be injected through the injection fitting 22
20 to infuse the washer 12 with lubricant.
Referring to Fig. 2, another embodiment of the present invention is
shown. The valve 2 of this embodiment comprises a stem 10 having
threads (not shown), a receptacle for lubricant, such as injection fitting 22, ahole 13 in the stem 10 for filling the stem relief hole 19 of the gate 17 with
25 lubricant, and a channel or hole 14 that connects the receptacle 22 to the
hole 13. The injection fitting 22 is connected anteriorly to the stem 10. The
hole 14 runs the length of the stem 10 between the injection fitting 22 and
the hole 13 in the bottom of the stem 10. With the gate 17 in the open
position, which is depicted in Fig. 2, the lubricant fills the stem relief hole 19
30 of gate 17, thereby forcing lubricant onto the stem threads. As the gate 17
is closed, lubricant is forced onto the threads of the lift nut 18.
Referring to Fig. 3, a further embodiment of the present invention is
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shown. The valve 3 of this embodiment comprises a stem 10 having
threads 11, a receptacle for lubricant, such as injection fitting 22, a hole 13
for distributing lubricant to the threads 11 of the stem 10, and a channel or
hole 14 that connects the receptacle 22 to the hole 13. The injection fitting
22 is disposed anteriorly to the stem 10. The valve 3 comprises a check
valve 23 between the hole 13 and the hole 14 that restricts lubricant flow
from the hole 13 back up the hole 14. The check valve 23 is a spring
loaded valve preferably located in the lower portion of hole 14. A pipe plug
24 blocks the end of hole 14 and retains the spring loaded ball check valve
23 in position.
Referring to Fig. 4, a further embodiment of the present invention is
shown. The valve 4 of this embodiment comprises a stem 10 having
threads (not shown), an injection fitting 22 for supplying lubricant, a hole 13
for distributing lubricant to the threads of the stem 10, and a channel or
hole 14 that connects the injection fitting 22 to the hole 13. The stem 10
may be set to force the lubricant to pass through a transverse hole 8 that
connects with the longitudinal hole 14. The lubricant injection fitting 22 is
located on a bonnet flange 21. The lubricant hole 14 comprises the
distribution hole 13 at the lower end of the stem 10, up through the center
of the stem 10, through the transverse hole 8 in the backseat shoulder 20,
and through a channel or hole 7 in the bonnet flange 21. This embodiment
allows for lubrication when the gate 17 is first closed. The lubricant is
injected through the bonnet flange lubricant fitting 22. The lubricant passes
through the hole 7 in the bonnet flange 21, through the hole 8 in the stem
back seat shoulder 20, down the hole 14 in the center of the stem 10, and
out hole 13. The lubricant then fills the stem relief hole 19 in the gate 17.
As the gate 17 is opened, lubricant is forced onto the stem threads (not
shown in Fig. 4). After the lubrication process has been completed, the
gate 17 is returned to its normal operating position. The valve 4 also
comprises a vent hole 25 through the side of the gate 17 located near the
lift nut 18.
It should be noted that while the invention has been described in
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terms of the preferred embodiments wherein the hole 14 is located down
the longitudinal central axis of the stem 10, it need not necessarily be so
located; for example, the hole 14 may be located down the outside of the
valve casing around the stem. In such an embodiment, a distribution hole
5 or holes would be located through the casing to allow for lubricant
communication to the threads, etc.
While the particular embodiments for lubricating threads of a valve as
herein shown and disclosed in detail is fully capable of obtaining the objects
and advantages herein before stated, it is to be understood that they are
10 merely illustrative of the presently preferred embodiments of the invention
and that no limitations are intended by the details of construction or design
herein shown.
