Note: Descriptions are shown in the official language in which they were submitted.
CA 02808708 2013-03-01
SHUTOFF VALVE
=
TECHNICAL FIELD
[0001] Shutoff valves for hydraulic systems.
BACKGROUND
[0002] Universe Machine Corporation has for many years supplied power tongs
into
the Canadian and United States oil field market place. The power tongs have a
throat for
receiving an oilfield tubular. A ring gear driven by motors engages the
oilfield tubular. A
hydraulic system supplies hydraulic power fluid to motors that drive the ring
gears. To
prevent the oilfield tubular exiting the throat of the power tong during use,
the throat has a
gate or door. Cable or hydraulic mechanisms have been used to shut off the
hydraulic supply
to the motors when the gate or door is opened. Cable mechanisms sold by
Universe Machine
Corporation have used a two piece valve shut off.
SUMMARY
[0003] There is provided a power tong with a cable operated door jammer
valve for
shutting off the hydraulic supply of a power tong when the door is opened. In
an
embodiment, there is provided a power tong comprising a ring gear and cage
assembly
having a throat, the ring gear and cage assembly being driven by a motor
having a hydraulic
supply, a door mounted on a pivot on the ring gear and cage assembly for
movement to open
and close the throat, a cable secured to the door at a point that is offset
from the pivot, the
cable extending through a sleeve to a valve end of the cable, a valve at the
valve end of the
cable, the valve having a valve housing and being operable by movement of a
valve control
to disengage the hydraulic supply from the motor, the valve end of the cable
being connected
to the valve control and the sleeve being connected to the valve housing.
[0004] There is provided a shutoff valve having a valve housing, a first
fluid port in
the valve housing, a second fluid port in the valve housing, a third fluid
port in the valve
housing, a fourth fluid port in the valve housing, and the valve being movable
between first
and second configurations, the first configuration allowing fluid flow between
the first fluid
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port and the second fluid port and between the third fluid port and the fourth
fluid port, the
first configuration not allowing fluid flow between the first fluid port and
the fourth fluid
port, and the second configuration blocking flow between the first fluid port
and the second
fluid port and between the third fluid port and the fourth fluid port, the
second fluid
configuration allowing fluid flow between the first fluid port and the fourth
fluid port.
[0005] In an embodiment, the valve may comprise a valve housing having a
bore for
receiving a valve spool, a valve spool movable between a first position and a
second position
within the bore, a first fluid port in the valve housing connected to the bore
by a first flow
passage within the valve housing and a second fluid port in the valve housing
connected to
the bore by a second flow passage within the valve housing, the valve spool
being
configured to allow fluid flow between the first flow passage and the second
flow passage
when the valve spool is in the first position, and the valve spool being
configured to block
fluid flow between the first flow passage and the second flow passage when the
valve spool
is in the second position, a third fluid port in the valve housing connected
to the bore by a
third flow passage within the valve housing and a fourth fluid port in the
valve housing
connected to the bore by a fourth flow passage within the valve housing, the
valve spool
being configured to allow fluid flow between the third flow passage and the
fourth flow
passage when the valve spool is in the first position, and the valve spool
being configured to
block fluid flow between the third flow passage and the fourth flow passage
when the valve
spool is in the second position, and the first fluid port being connected to
the bore by a fifth
flow passage within the valve housing, and the fourth fluid port being
connected to the bore
by a sixth flow passage within the valve housing. the valve spool being
configured to block
fluid flow between the fifth flow passage and the sixth flow passage when the
valve spool is
in the first position, and the valve spool being configured to allow fluid
flow between the
fifth flow passage and the sixth flow passage when the valve spool is in the
second position.
[0006] In further embodiments the valve may have one or more of the
following
features: the shutoff valve may be substantially axially symmetric, the valve
spool having
thinner portions that allow fluid flow in the portions of the bore through
which the thinner
portions pass and having thicker portions that block fluid flow in the
portions of the bore
through which the thicker portions pass; the valve may be mounted in a
hydraulic system
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with a hydraulic fluid source having an output line and a return line, and a
hydraulic device
having a input line and a drain line, in which the first fluid port is
connected to the output
line of the hydraulic fluid source, the second fluid port is connected to the
input line of the
hydraulic device, the third fluid port is connected to the drain line of the
hydraulic device,
and the fourth fluid port is connected to the return line of the hydraulic
fluid source; the
valve may be mounted in a hydraulic system with a hydraulic fluid source
having an output
line and a return line, and a hydraulic device having a input line and a drain
line, in which
the first fluid port is connected to the input line of the hydraulic device,
the second fluid port
is connected to the output line of the hydraulic fluid source, the third fluid
port is connected
to the return line of the hydraulic fluid source, and the fourth fluid port is
connected to the
drain line of the hydraulic device; the shutoff valve may be mounted in a
hydraulic system
with a hydraulic fluid source having an output line and a return line, and a
hydraulic device
having a input line and a drain line, in which the first fluid port is
connected to the return
line of the hydraulic fluid source, the second fluid port is connected to the
drain line of the
hydraulic device, the third fluid port is connected to the input line of the
hydraulic device,
and the fourth fluid port is connected to the output line of the hydraulic
fluid source; the
valve may be mounted in a hydraulic system with a hydraulic fluid source
having an output
line and a return line, and a hydraulic device having a input line and a drain
line, in which
the first fluid port is connected to the drain line of the hydraulic device,
the second fluid port
is connected to the return line of the hydraulic fluid source, the third fluid
port is connected
to output line of the hydraulic fluid source, and the fourth fluid port is
connected to the input
line of the hydraulic device; the valve may be mounted in a hydraulic system
comprising
power tongs; the valve may be mounted in a hydraulic system comprising a motor
operating
power tongs, the power tongs having a throat and a door to prevent an oilfield
tubular from
exiting the throat.
[0007] There is provided a hydraulic system with a hydraulic fluid
source and a
hydraulic device comprising power tongs, the hydraulic system including a
shutoff valve,
the shutoff valve comprising a valve housing having a bore for receiving a
valve spool; the
valve spool movable between an open position and a closed position within the
bore, the
valve spool being moved to the closed position based on operation of a valve
control; the
valve housing comprising a first fluid port, a second fluid port, a third
fluid port, and a
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fourth fluid port, in which the first fluid port is connected to an output
line of the hydraulic
fluid source, the second fluid port is connected to an input line of the
hydraulic device, the
third fluid port is connected to a drain line of the hydraulic device, and the
fourth fluid port
is connected to a return line of the hydraulic fluid source; an internal
hydraulic bypass
comprising: a gap between the valve spool and the bore; a first bypass flow
passage within
the valve housing connecting between the first fluid port and the gap when the
valve spool is
in the closed position; a second bypass flow passage within the valve housing
connecting
between the fourth fluid port and the gap when the valve spool is in the
closed position; in
which the valve spool and valve housing define a first flow passage between
the first flow
port and the second flow port and a second flow passage between the third flow
port and the
fourth flow port when the valve spool is in the open position, and the valve
spool is
configured to block fluid flow between the first flow port and the second flow
port and
between the third flow port and the fourth flow port when the valve spool is
in the closed
position; and a first seal plate within the bore providing a seal between the
first flow passage
and the gap, and a second seal plate on the opposite side of the bore relative
to the gap
providing a seal between the second flow passage and the gap. In various
embodiments the
shutoff valve may have one or more of the following features: the valve spool
is
substantially axially symmetric, the valve spool having thinner portions that
allow fluid flow
in the portions of the bore through which the thinner portions pass and having
thicker
portions that block fluid flow in the portions of the bore through which the
thicker portions
pass; the shutoff valve is operable by pulling on a cable connected to the
valve control by a
linkage, moving the valve spool from the open position to the closed position;
the hydraulic
device is a motor operating power tongs, the power tongs having a throat and a
door to
prevent an oilfield tubular from exiting the throat, the door being connected
to the cable and
configured to pull on the cable when the door is not closed; the valve spool
is in the open
position when the door is closed. These and other aspects of the device are
set out in the
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0008] Embodiments will now be described with reference to the figures,
in which
like reference characters denote like elements, by way of example, and in
which:
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[0009] Fig. 1 shows a hydraulic circuit for a power tong;
[0010] Fig. 2 shows a ring gear and cage assembly of a power tong;
[0011] Fig. 3 shows a cable operated door jammer valve for use with the
ring gear
and cage assembly of Fig. 2;
[0012] Fig. 4A shows a shutoff valve in an open position, from a
viewpoint aligned
with the inputs and outputs to the valve;
[0013] Fig. 4B shows the shutoff valve of Fig. 4A in an open position,
from a
viewpoint perpendicular to the inputs and outputs to the valve;
[0014] Fig. 5A shows the shutoff valve of Fig. 4A in a closed position,
from a
viewpoint aligned with the inputs and outputs to the valve; and
[0015] Fig. 5B shows the shutoff valve of Fig. 4A in a closed position,
from a
viewpoint perpendicular to the inputs and outputs to the valve.
DETAILED DESCRIPTION
[0016] Immaterial modifications may be made to the embodiments described
here
without departing from what is covered by the claims. In the claims, the word
"comprising"
is used in its inclusive sense and does not exclude other elements being
present. The
indefinite article "a" before a claim feature does not exclude more than one
of the feature
being present. Each one of the individual features described here may be used
in one or
more embodiments and is not, by virtue only of being described here, to be
construed as
essential to all embodiments as defined by the claims.
[0017] Referring to Figs. 1 and 2, a power tong 10 comprises a
conventional ring
gear and cage assembly 8 (Fig. 2) and hydraulic power circuit 12 (Fig. 1). The
hydraulic
power circuit 12 comprises a hydraulic supply 14 that supplies hydraulic fluid
to motor 16
through lines 18. A shut off valve 20 is provided on the lines 18. The ring
gear and cage
assembly 8 has a throat 22 and the ring gear and cage assembly 8 is driven by
the motor 16.
The cooperation of the ring gear and cage assembly with the motor is known in
the art and
need not be described further here.
[0018] A door 24 is mounted on a pivot 26 on the ring gear and cage
assembly 8 for
movement to open and close the throat 22. A cable 28 is secured to the door 24
at a
connection point 30 that is offset from the pivot 26. The cable 28 extends
through a sleeve
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32 to a valve end 34 of the cable 28. The sleeve 32 may be secured at various
points along
the power tong body 10.
[0019] The valve 20 is located on the power tong body 10 away from the
throat 22 at
the rear of the ring gear and cage assembly 8 and adjacent the hydraulic
supply 14. The
valve 20 is at the valve end 34 of the cable 28 and has a valve housing 36.
The valve 20 is
operable by movement of a valve control 38 to disengage the hydraulic supply
14 from the
motor 16. The valve 20 is a conventional shut off valve in one embodiment, and
may be a
diverter valve in another embodiment. The valve end 34 of the cable 28 is
connected to the
valve control 38 via a rigid linkage 40. The sleeve 32 is connected and
secured to the valve
housing 36 by any of suitable means such as by welding nut 42 to the housing
36 of the
valve 20.
[0020] The linkage 40 through which the cable 28 is connected to the
valve control
38 may comprise in one embodiment a drive rod 44 having a main section 46
lying parallel
to a wall 48 of the valve housing 36 and having an extension 50 extending
laterally to the
main section 46 to a connection point 52 with the valve control 38.
[0021] When the door 24 is opened in the direction of arrow A to open
the throat 22,
the connection point 30 rotates around the pivot 26 as shown by arrow B, thus
pulling on the
cable 28. The cable 28 moves through fixed sleeve 32 and pulls on the linkage
40, which
pulls on the valve control 38 to operate the valve 20 and shut off hydraulic
fluid supply to
the motor 16.
[0022] Figs. 4A-5B show an embodiment of the shutoff (safety interlock)
valve.
The valve spool H moves between two positions within a valve housing I, an
open position
shown in Figs. 4A-4B that allows fluid to flow between port D and port E and
between port
F and port G, and a closed position shown in Figs. 5A-5B that blocks fluid
flow into or out
of port E and into or out of port F but allows fluid flow between port D and
port G. How it
works is when the spool is closed the groove C connects ports D & G through
the cross
drilled holes A & B. As previously described, in the context of hydraulic
power tongs the
shutoff valve should generally be installed such that when door 24 is open the
valve spool H
is in the closed position and when door 24 is closed the valve spool H is in
the open
position. The valve can be installed in multiple configurations. In a typical
configuration,
when the valve is open oil from hydraulic supply 14 enters through port D and
exits through
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port E to drive motor 16. Return oil from motor 16 enters through port F and
exits through
port G. In this configuration, when the shutoff valve is closed, but the
hydraulic supply 14 is
continuing to supply fluid, inflow into port D is allowed to flow through A
and B back to G
thus reducing the pressure on the spool and 0-rings J. It also will greatly
reduce the oil
from leaking across the spool from port D to E and back through F to G which
further
increased the effectiveness of the safety interlock valve. In another
configuration, the valve
is connected so that oil from supply 14 flows into port E and out through port
D to motor 16,
and returns from motor 16 through ports G and F. In this configuration if oil
pressure is
applied to port E, any leakage across the spool to port D will go through the
cross drilled
holes A & B thus eliminating any differential pressure across the ports D and
G thus making
it impossible to cause any device attached to ports D and G to operate. This
allows any oil
that leaks past the spool to not pass through the motor thus further reducing
the chance of
the motor starting to creep rotate. The Safety interlock valve can also be
connected in
reverse so that oil pressure is applied via ports F and G and return flow is
through ports D
and E.
[0023] In the embodiment shown the valve spool H is axially symmetric
for ease of
construction. The valve spool has thicker portions that block flow through the
portions of
the bore through which the thicker portions pass, and thinner portions such as
groove C that
allow flow through the portions of the bore through which the thinner portions
pass. The
portions of the bore through which the thicker portions of the valve spool
pass and the
portions of the bore through which the thinner portions of the valve spool
pass depend on
the position of the valve spool.
[0024] The internal valve system of the safety interlock valve can
provides the
control valve spool seal plate damage protection. When the primary valve
(motor spool) is
activated and the door lock system is engaged, the internal 1/4" ports soften
any pressure
surges in the primary valve section lessening the deformation of valve spool
seal plates and
likelihood of extrusion of the primary valve spools seals. This system is
designed to
mitigate pressure spikes when on operator pulls the wrong lever or bumps the
lever when
the door lock is activated. This internal hydraulic bypass can also ensure
that any leakage
from the primary valve (motor control valve) would not advance into the motor
through the
internal leakage of the door safety valve, thus negating the possibility of
motor creep as well
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as extending motor seal life and seal plate extrusion (specifically the
internally case drained
Rineer motor).
[0025] In a further embodiment (not shown) the spool could have an
additional
groove, and additional cross drilled holes connected to port E and port F
respectively could
be connected through the additional groove when the valve spool is in the
closed position.
This further embodiment would both allow any incoming fluid to flow directly
to the return
line, and allow equalization of pressure of any leaked oil, at the expense of
increased
complexity.
[0026] The safety interlock valve can be used in conjunction with a
detector for
detecting a condition under which continued flow may be unsafe to shut off the
flow of fluid
in the event of detecting the condition. Depending on the embodiment, the
detector may be
configured to also operate the valve through an actuator to re-enable flow in
the event that
the condition is not present, or may be configured, for example using a latch
or other
mechanism, to keep the valve in the closed position until manually reset.
[0027] In the context of hydraulic tongs the shut off valve may also be
mounted so
that it will stop the flow of oil from the valve which actually controls the
power tong
rotation. However if the tong has a multiple valve bank the other valves are
not affected by
this shutoff.
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