Note: Descriptions are shown in the official language in which they were submitted.
DOUBLE-PISTON-EFFECT VALVE
FIELD
[0001] The present application relates to a valve, in particular to a double-
piston-effect
valve.
BACKGROUND
[0002] A conventional trunnion ball valve generally employs a single upstream
valve seat
to obtain the sealing effect, and a downstream valve seat barely has the
sealing effect. A
double piston effect for a ball valve mainly uses both the upstream and
downstream valve
seats to obtain the sealing effect. Even though the upstream valve seat fails
to seal the valve,
the downstream valve seat can still seal the valve; therefore the sealing
effect is effectively
improved by this method. This method not only improves the sealing effect of
the ball valve
but also prolongs the working life of the ball valve. The ball valve with this
structure has been
used in the petroleum industry for years. However, the application of this
technology causes
the design of the valve seat to be excessively complicated, the assembling and
replacement on
site to be difficult and the manufacturing cost to be excessively high.
SUMMARY
[0003] A double-piston-effect valve is provided according to the present
application, which
has a better sealing effect and a low cost, and is easy to manufacture,
assemble, maintain and
replace on site.
[0004] The technical solution of the present application is described as
follows. A
double-piston-effect valve includes a central valve body, a valve ball located
in the central
valve body, two valve endcaps symmetrically arranged at two opposing sides of
the valve ball
and engaged with two opposing sides of the central valve body, and two valve
seats
symmetrically arranged in the two valve endcaps, respectively, and each valve
seat is located
between the valve ball and the respective valve endcap. A piston ring is
arranged on a rear of
each of the valve seats, an inner 0-ring groove is provided in an inner
circumferential surface
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of the piston ring, an outer 0-ring groove is arranged in an outer
circumferential surface of the
piston ring, a first 0-ring is fitted in the inner 0-ring groove, a second 0-
ring is fitted in the
outer 0-ring groove, and a first side, away from the valve ball, of the piston
ring is further
provided with an annular protruding portion, and two semi-circular notches are
symmetrically
provided in the annular protruding portion of the piston ring.
[0005] Compared with the conventional technology, the present application has
the
following advantages. The double-piston-effect valve with this structure is
additionally
provided with a piston ring on the rear of the valve seat, and the piston ring
can automatically
adjust according to a high-pressure side. Since there is a pressure difference
between the
high-pressure side and a low-pressure side, a sealing effect can be realized
by a hydrostatic
force induced from this differential pressure. Two 0-rings, including an inner
0-ring and an
outer 0-ring, are embedded in the piston ring, which can realize a close
cooperation between
the piston ring and a valve seat insert, and thus no matter which direction
the medium flows,
the sealing effect can always be realized. The double-piston-effect valve has
the following
advantages. The design of the valve seat is unsophisticated, and the valve
also has an
improved sealing effect and a low cost, and is easy to manufacture, assemble,
maintain and
replace on site. The double-piston-effect valve in the present application
simplifies the
conventional technology and can be employed in any trunnion ball valve which
is applicable
for petroleum, industry, land exploration, offshore exploration and
production.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Fig. 1 is a sectional view of a double-piston-effect valve according to
an
embodiment of the present application;
[0007] Fig. 2 is an enlarged view of portion A in Fig. 1;
[0008] Fig. 3 is a schematic perspective view showing the structure of a
piston ring
according to the embodiment of the present application;
[0009] Fig. 4 is a partially sectional view of the double-piston-effect valve
with the piston
ring located at the right limit position; and
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[0010] Fig. 5 is a partially sectional view of the double-piston-effect valve
with the piston
ring located at the left limit position.
DETAILED DESCRIPTION
[0011] Embodiments of the present application are described in conjunction
with the
drawings. As shown in Fig. 1, a double-piston-effect valve includes a central
valve body 10, a
valve ball 11 located in the central valve body 10, and two valve endcaps 1
symmetrically
arranged at two opposing sides of the valve ball 11 and engaged with two
opposing sides of
the central valve body 10. Two valve seats 2 are symmetrically arranged in the
two valve
endcaps 1, respectively, and each valve seat 2 is located between the valve
ball 11 and the
respective valve endcap 1. Referring to Fig. 2, the valve seat 2 includes a
first section 21
facing the valve ball 11, a second section 22 away from the valve ball 11, and
a third section
23 between the first section 21 and the second section 22. A diameter D1 of
the first section
21 is greater than a diameter D3 of the third section 23, and the diameter D3
of the third
section 23 is greater than a diameter D2 of the second section 22, thus, an
outer surface of the
valve seat 2, engaged with the valve endcap 1, forms a stepped shape, and
accordingly, the
valve endcap 1 is provided with a stepped bore to accommodate the valve seat
2.
[0012] A piston ring 3 is arranged on a rear of each of the two valve seats 2.
Referring to
Fig. 2, the piston ring 3 is arranged at a rear side, away from the valve ball
11, of the valve
seat 2. Specifically, the piston ring 3 is sleeved on the second section 22 of
the valve seat 2,
and an inner diameter of the piston ring 3 is greater than the diameter D2 of
the second
section 22 of the valve seat 2, which allows the piston ring 3 to move freely
on the valve seat
2. An inner 0-ring groove 4 is provided in an inner circumferential surface of
the piston ring 3,
and a first 0-ring 41 is fitted in the inner 0-ring groove 4. An outer 0-ring
groove 5 is
provided in an outer circumferential surface of the piston ring 3, and a
second 0-ring 51 is
fitted in the outer 0-ring groove 5. In a preferable solution, the inner 0-
ring groove 4 and the
outer 0-ring groove 5 are staggered from each other with respect to the width
of the piston
ring 3. By staggering the inner 0-ring groove 4 from the outer 0-ring groove
5, the space of
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the piston ring 3 is effectively used, which further improves the strength of
the piston ring 3,
to better meet the strength requirement.
[0013] As shown in Fig. 2, a valve seat insert 8 is installed in an end
surface 24, facing the
valve ball 11, of the valve seat 2. When the valve is assembled, the piston
ring 3 is sleeved on
the valve seat 2 and the valve seat 2 is fitted into the valve endcap 1, the
second 0-ring 51
received in the outer 0-ring groove 5 engages with an inner surface of the
valve endcap 1, and
the first 0-ring 41 received in the inner 0-ring groove 4 engages with the
outer surface of the
second section 22 of the valve seat 2. In this state, an outer diameter of the
second 0-ring 51
is greater than an outer diameter D4 of the valve seat insert 8, and an inner
diameter of the
first 0-ring 41 is smaller than an inner diameter D5 of the valve seat insert
8, thus, a
bidirectional sealing effect can be realized.
[0014] Referring to Figs. 2 and 3, an annular protruding portion 6 is provided
on the piston
ring 3, and two semi-circular notches 7 are symmetrically provided in the
annular protruding
portion 6, and the two semi-circular notches 7 are configured to keep a grease
chamber and a
body cavity to be in communication with each other.
[0015] In a preferable solution, the annular protruding portion 6 is provided
at a first end of
the piston ring 3, and when the valve is assembled, the first end of the
piston ring 3 is away
from the valve ball 11. The first end of the piston ring 3 is further provided
with a chamber.
Reference is made to Figs. 4 and 5, in which a grease fitting 13 provided in
the valve endcap
1 is shown. In a first state of the working process of the valve as shown in
Fig. 4, the direction
of hydrostatic load P is rightward, the piston ring 3 moves to the right limit
position, a gap is
formed between the inner surface of the valve endcap 1 and the first end of
the piston ring 3,
thus the lubricant can be filled from the grease fitting 1 into a lubricating
passage in the valve
seat 2 through the gap, the chamber, and the semi-circular notches 7. In a
second state of the
working process of the valve as shown in Fig. 5, the direction of hydrostatic
load P is leftward,
the piston ring 3 moves to the left limit position, the first end of the
piston ring 3 sits against
the inner surface of the valve endcap 1, and in this state, due to the chamber
and the
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semi-circular notches 7 arranged in the piston ring 3, the lubricant can still
be filled from the
grease fitting 13 into the lubricating passage in the valve seat 2 through the
chamber, and the
semi-circular notches 7. Therefore, regardless of the direction of hydrostatic
load P, the
lubricating passage of the valve seat 2 will not be blocked.
[0016] The piston ring of the double-piston-effect valve can automatically
adjust according
to a high-pressure side and realize a sealing effect by utilizing a
hydrostatic pressure.
[0017] In a further embodiment, again referring to Fig. 2, a spring 9 is
provided on the
valve seat 2. Specifically, the spring 9 is sleeved on the third section 23 of
the valve seat 2,
and is configured to provide spring load to energize the valve seat 2 to
enable the sealing
performance when the hydrostatic pressure is low. When the valve is assembled,
the spring 9
is located between the inner surface of the valve endcap 1 and the first
section 21 of the valve
seat 2. The spring 9 can be embodied as a wave spring or a compression spring,
and other
types of spring can also be used as long as the spring can provide the
required spring load.
[0018] The piston ring of the double-piston-effect valve can automatically
adjust according
to the high-pressure side and realize the sealing effect by utilizing the
hydrostatic pressure and
spring loads.
[0019] The two 0-rings, including the inner 0-ring and the outer 0-ring, are
embedded in
the piston ring, which can realize a close cooperation between the piston ring
and a valve seat
insert, and thus no matter which direction the medium flows, the sealing
effect can always be
realized (that is, the bidirectional sealing effect can be realized).
[0020] The above descriptions are only preferable embodiments of the present
application.
It should be noted that, for those ordinary skilled in the art, a few of
modifications and
improvements may be made to the present application without departing from the
principle of
the present application. The scope of protection of the present application is
defined by the
claims.
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