Note: Descriptions are shown in the official language in which they were submitted.
CA 02636751 2015-01-27
SWIVEL JOINT WITH UNIFORM BALL BEARING REQUIREMENTS
BACKGROUND OF THE INVENTION
1. Technical Field
[0002] The present invention relates in general to swivels joints for high
pressure well service
applications and, in particular, to an improved system, method, and apparatus
for swivel joints
having uniform ball bearing requirements for all bearing races.
2. Description of Related Art
[0003] High pressure well service applications require the use of swivel
joints to interconnect
various plumbing configurations. A swivel joint has male and female connectors
that are joined
and sealed, but which permit swivel action between them. Circumferential
bearing seats are
formed in the male and female connectors to capture ball bearings therebetween
to facilitate the
swiveling action. Swivel joints are required to perform under extreme
conditions, such as
handling fluids that contain abrasives that cause erosion of the joint
components, high pressures,
and extreme temperatures. Although there are workable designs available in the
industry, an
improved swivel joint design would be desirable.
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SUMMARY OF THE INVENTION
[0004] Embodiments of a system, method, and apparatus for a swivel joint
having uniform ball
bearing requirements for all bearing races are disclosed. The swivel joint has
a male connector
and a female connector that coaxially interconnect and swivel relative to each
other while still
maintaining a high pressure seal. Each connector has three bearing races to
form three sets of
bearing races, each of which supports the same number of ball bearings. The
circumferences of
the main races are enlarged by less than the diameter of one ball, so it is
impossible to add
another ball to the coupled male and female connectors of the swivel joint.
[0005] For example, the main and center male connector bearing races are
formed at one
diameter, while the third bearing race is formed at a larger diameter. The
female races are
formed at complementary configurations. In addition to providing diametric and
circumferential
dimensional changes, this design also provides an increase in wall thickness
for greater erosion
resilience.
[0006] An increased step in diameter may be formed on the outer diameter of
the male connector
between the races, with a complementary step in diameter formed on the inner
diameter of the
female connector between its races. This design results in more support around
the main ball
races that are closest to the seal ring. This configuration also produces more
even distribution of
loads and stresses throughout all of the ball races, and provides extended
life of the ball races.
[0007] One embodiment of the invention also is provided with greater axial
separation between
the various sets of ball races compared to conventional designs. For example,
the axial distance
between each set of races is increased. This wider stance between ball races
results in a more
stable ball race assembly and provides better ball race loading and longer
ball race life.
CA 02636751 2015-01-27
[0007AI In one broad aspect, the invention pertains to, in combination with a
swivel
joint forming a flow passage and having a central axis, an improvement
comprising a
hollow tubular male connector having a first end, and an annular outer surface
having
a main bearing race, a center bearing race, and a support bearing race. Each
of the
main, center and support bearing races has an arcuate cross-section of a same
radius, and
wherein the main bearing race's diameter is relative to the central axis being
the same
as the center bearing race's diameter and less than the support bearing race's
diameter.
The support bearing race is furthest from the first end than the main and
center bearing
races, and the main bearing race is closest to the first end. A hollow tubular
female
connector has corresponding female main bearing race, female center bearing
race, and
female support bearing race adapted to receive and fit around the outer
surface and the
main bearing race. The center bearing race, and the support bearing race of
the male
connector to respectively form main, center, and support bearing cavities have
a
substantial circular cross section of the same cross sectional diameter. A
raised step
circumscribes the male connector between the support bearing race and center
bearing
race. The raised step defines a change of diameter with respect to the central
axis to
increase the male connector's wall thickness near the male support bearing
race. There
is a recess step in the female connector, the recess step corresponding to the
raised step
and increasing the female connector's wall thickness near the female main
bearing race
and the female center bearing race. A same number of balls haveg a same outer
diameter in each of the main, center, and support bearing cavities, such that
the support
bearing cavity holds the same number of balls to a full capacity that no
additional ball
of the same outer diameter can be placed into each of the main, center, and
support
bearing cavities. The same number of balls are supported only by the races and
themselves.
[0008] The foregoing and other aspects and advantages of the present invention
will be
apparent to those skilled in the art, in view of the following detailed
description of the
present invention taken in conjunction with the appended claims and the
accompanying
drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0009] So that the manner in which the features and advantages of the present
invention, which
will become apparent, are attained and can be understood in more detail, more
particular
description of the invention briefly summarized above may be had by reference
to the
embodiments thereof that are illustrated in the appended drawings which form a
part of this
specification. It is to be noted, however, that the drawings illustrate only
some embodiments of
the invention and therefore are not to be considered limiting of its scope as
the invention may
admit to other equally effective embodiments.
[0010] FIG. 1 is an isometric view of one embodiment of a swivel joint
constructed in
accordance with the invention;
[0011] FIG. 2 is a sectional view of the swivel joint of FIG. 1 and is
constructed in accordance
with the invention;
[0012] FIG. 3 is a sectional view of one embodiment of a male connector for a
swivel joint and
is constructed in accordance with the invention;
[0013] FIG. 4 is a sectional view of one embodiment of a female connector for
a swivel joint and
is constructed in accordance with the invention;
[0014] FIG. 5 is a sectional view of another embodiment of a male connector
for a swivel joint
and is constructed in accordance with the invention; and
[0015] FIG. 6 is a sectional view of another embodiment of a female connector
for a swivel joint
and is constructed in accordance with the invention.
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DETAILED DESCRIPTION OF THE INVENTION
[0016] Referring to FIGS. 1 - 6, embodiments of a system, method, and
apparatus for swivel
joints having uniform ball bearing requirements for all bearing races are
disclosed. As shown in
FIGS. 1 and 2, one type of swivel joint 11 comprises a male connector 13 and a
female connector
15 that coaxially interconnect along central axes 12, 14 thereof. The swivel
joint 11 also
includes connectors 17, 19 for connecting the swivel joint to other well
service components (not
shown). The swivel joint permits the male and female connectors 13, 15 to
swivel about the axes
12, 14 relative to each other while still maintaining a high pressure seal
therebetween.
[0017] FIGS. 3 and 4 depict enlarged sectional views of one embodiment of male
and female
connectors 13, 15, respectively, such as for 3-inch diameter components rated
at a working
pressure of 15,000 psi. A main seal ring 16 (FIG. 2) for the swivel joint 11
is located between
distal end 17 (FIG. 3) of male connector 13, and proximal end 19 (FIG. 4) of
female connector
15. As shown in FIG. 2, an o-ring 18 and dust seal 20 also may be provided
between connectors
13, 15.
[0018] Male connector 13 also has three bearing races 21, 23, 25, that are
coaxial with and
complementary to three bearing races 31, 33, 35 located on female connector
15. Thus, when
male and female connectors 13, 15 are mated together, three sets of bearing
races are formed:
main set races 21, 31; center set races 23, 33, and support set races 25, 35,
each of which
supports a plurality of ball bearings or balls 22.
[0019] In one embodiment, each set of races contains the same number of balls
22. For
example, each set of races may be provided with a total of 35 balls, with each
ball having a
diameter of 3/8-inch. However, the sets of races are not all the same size.
For example,
although main set races 21, 31 and center set races 23, 33 may be provided
with the same
diameters, support set races 25, 35 may be provided with larger diameters.
With respect to some
conventional designs having small main set races, this design may be
accomplished by enlarging
the diameter and circumference of main set races 21, 31 by a sufficient
distance to almost
accommodate another ball (e.g., approximately 3/4 to 7/8 of the diameter of
one ball). Since the
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circumference of main set races 21, 31 are enlarged by less than the diameter
of one ball, it is
impossible to add another ball to the coupled male and female connectors 13,
15 of swivel joint
11.
[0020] For example, in the embodiment of FIG. 3, the male connector bearing
races 21, 23 are
formed at a diameter 41 of about 3.843 inches, while bearing race 25 is formed
at a diameter 43
of about 3.903 inches. In a complementary configuration, the female connector
bearing races 31,
33 (FIG. 4) may be formed at a diameter 45 of about 4.60 inches, while bearing
race 35 may be
formed at a diameter 47 of about 4.66 inches.
[0021] In addition to providing diametral and circumferential dimensional
changes, this design
also provides an increase in wall thickness (i.e., radial direction). In one
embodiment, the wall
thickness of the male connector 13 is increased by about 13.5% for greater
erosion resilience
therethrough. As shown in FIGS. 2-4, a step 49 in diameter (i.e., radial
thickness of the wall)
may be formed on the outer diameter of male connector 13 between races 23, 25,
with a
complementary shaped step 50 in diameter formed on the inner diameter of
female connector 15
between races 33, 35.
[0022] One embodiment of the invention also is provided with greater axial
separation between
the various sets of ball races compared to conventional designs. For example,
on the male
connector 13 (FIG. 3), the axial distance between ball races 21 and 23 is
increased to at least
about 0.88 inches, as is the axial distance between ball races 23 and 25.
Complementary
dimensions are formed on the female connector 15. This wider stance between
ball races results
in a more stable ball race assembly and provides better ball race loading and
longer ball race life.
[0023] Referring now to FIGS. 2 and 4, the female connector 15 may be provided
with an outer
diameter configuration that includes a step 51 in radial thickness of the
wall. For example, in
the embodiment shown, the step 51 is located adjacent the center race 33. The
wall of connector
15 is thicker and has a larger diameter (e.g., approximately 5.41 inches)
about main race 31, and
a smaller diameter (e.g., approximately 5.34 inches) about support race 35.
This design results in
more support around the main ball races that are closest to the seal ring 16
(FIG. 2). This
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configuration also produces more even distribution of loads and stresses
throughout all of the
ball races, and provides extended life of the ball races.
[0024] Referring now to FIGS. 5 and 6, another embodiment of male and female
connectors 113,
115, such as for 4-inch diameter components rated at a working pressure of
10,000 psi is shown.
This embodiment and the previously described embodiment share many features
and elements,
including the requirement that each race contain the same number of balls. For
example, each
set of races may be provided with a total of 32 balls, with each ball having a
diameter of 1/2-
inch.
[0025] Similarly, the sets of races are not all the same size. The main races
121, 131 and center
races 123, 133 may be provided with the same respective diameters, and support
races 125, 135
may be provided with larger respective diameters. This design may be
accomplished by
enlarging the diameter and circumference of main races 121, 131 by a
sufficient distance to
almost accommodate another ball. Since the circumference of the main races
121, 131 are
enlarged by less than the diameter of one ball, it is impossible to add
another ball to the coupled
male and female connectors 113, 115 of the swivel joint.
[0026] For example, in the embodiment of FIG. 5, the male connector races 121,
123 are formed
at a diameter 141 of about 4.637 inches, while support race 125 is formed at a
diameter 143 of
about 4.727 inches. In a complementary configuration, the female connector
races 131, 133
(FIG. 6) may be formed at a diameter 145 of about 5.647 inches, while support
race 135 may be
formed at a diameter 147 of about 5.737. This design also provides an increase
in wall thickness
of about 22.7% in one embodiment of the male connector 113. A step 149 in
diameter (i.e.,
radial thickness of the wall) may be formed on the outer diameter of male
connector 113 between
races 123, 125, with a complementary step 150 in diameter formed on the inner
diameter of
female connector 115 between races 133, 135.
[0027] The female connector 115 also may be provided with an outer diameter
configuration that
includes a step 151 (FIG. 6) in radial thickness of the wall. For example, in
the embodiment
shown, the step 151 is located adjacent the center race 133. The wall of
connector 115 is thicker
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and has a larger diameter (e.g., approximately 6.56 inches) about main race
131, and a smaller
diameter (e.g., approximately 6.44 inches) about support race 135.
[0028] While the invention has been shown or described in only some of its
forms, it should be
apparent to those skilled in the art that it is not so limited, but is
susceptible to various changes
without departing from the scope of the invention.
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