ROD GUIDE WITH WRAPPING VANES

GUIDE DE TIGE A AUBES ENVELOPPANTES

English Abstract

A sucker rod guide includes a pair of vanes, offset from one another by
180°, with each vane
wrapping approximately 180 around the rod guide. The vanes wrap around the
body of the
guide, and are neither spiral nor helical because the surfaces of the vanes
extending radially
outwardly from the body of the rod guide define two dimensional planar
surfaces, i.e. flat planes.
The vane thickness varies from a maximum at each end of the vane to a minimum
at a midway
point along the vane. This shape assists in moving fluid up the production
tubing when the guide
is applied to a rotary system, such as a progressive cavity pump. This shape
also enhances the
erodable volume of the vanes at the extremities, while providing a less
inhibiting path for the
flow of fluid in reciprocating applications.

Claims

What is claimed is:
1. A rod guide comprising:
an elongate cylindrical body;
a first vane extending radially outwardly from the body, the first vane
defining
opposing, parallel, flat, two-dimensional first and second side walls, the
first vane wrapping substantially half-way around the body; and
a second vane extending radially outwardly from the body, the second vane
defining opposing, parallel, flat, two-dimensional third and fourth side
walls, the first vane wrapping substantially half-way around the body.
2. The rod guide of claim 1, wherein the first and second vanes are offset
from
one another by substantially 180°.
3. The rod guide of claim 1, wherein the body defines a first end and a second
end, and further comprising:
a first conical end cap extending from the first end of the body; and
a second conical end cap extending from the second end of the body.
4. The rod guide of claim 1, wherein the first vane defines a first end, a
second
end, and a middle, and wherein the first vane defines a maximum width and the
first end
and the second end and a minimum width at the middle.
5. The rod guide of claim 4, further comprising:
a first conical end cap extending from the first end of the body;
a second conical end cap extending from the second end of the body;
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a first angled edge between the first end of the first vane and the first
conical end
cap; and
a second angled edge between the second end of the first vane and the second
conical end cap.
6. The rod guide of claim 5, wherein the first angled edge defines a first
straight,
non-wrapping vane segment and further wherein the second angled edge defines a
second
straight, non-wrapping vane segment.
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Description

CA 02743742 2011-06-17
ROD GUIDE WITH WRAPPING VANES
Field of the Invention
[0001] The present invention relates generally to the field of sucker rod
guides and
scrapers for removing paraffin and other extraneous materials from the
interior wall of
production tubing and protecting the tubing and sucker rod couplings from
excessive
wear. More particularly, the present invention relates to a sucker rod guide
with a pair of
helical vanes along a portion of the length of the guide and fluid flow
channels between
the vanes.
BACKGROUND OF THE INVENTION
[0002] Various types of rod guides and scrapers have been devised to remove
paraffin and other material from the interior wall of production tubing. Many
rod guides
include a cylindrical body molded onto a sucker rod and one or more vanes
projecting
radially from the body. In some cases, one or more vanes are substantially
straight (i.e.
parallel to the axis of the rod), and in other cases the vanes are slanted
(i.e. inclined at an
angle relative to the axis of the rod). In still other cases, the vanes may be
helical (i.e.
spiraling relative to the axis of the rod). The space between the vanes, or
between a
slanted vane, defines a flow path for production fluid past the rod guide.
[0003] Most rod guides today are manufactured from a polymeric material. Rod
guides may be secured in various ways to the sucker rod. In one application,
the rod
guide is molded onto the sucker rod and is thus immobile relative to the
sucker rod. In
other applications, the sucker rod includes an open seam which is opened in
order to affix
the rod guide to the sucker rod.
[0004] As described in U.S. Patent No. 7,731,885 to Abdo, for many
applications, a
rod guide provided with spiraling vanes is preferred over a straight or
slanted vane guide,
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CA 02743742 2011-06-17
since more of the circumference of the tubing may be cleaned by a single
spiraling guide
compared to a single straight-vane guide in a reciprocating rod application.
Spiraling rod
guide vanes shown and described by Abdo included a forward portion spiraling
in a
forward direction and a backward portion spiraling in a backward direction
rSotatably
opposite the forward direction. This arrangement creates a tortuous path,
however, and
causes high fluid drag forces to fluid passing between the rod guide and the
interior
surface of the production tubing.
[0005] U.S. Pat. No. 5,277,254 discloses a helical rod guide for use with a
progressing cavity pump rod. The helical guide may employ either one or two
lead
vanes. U.S. Pat. No. 6,182,754 discloses a helical scraper for a reciprocating
sucker rod.
Each of two vanes extends 180 about the body, with the ends of a flow channel
between
the vanes being parallel to the body of the sucker rod. U.S. Pat. No.
6,439,311 discloses
a method of retarding sand buildup by employing helical vanes which are
affixed to
connective rods by shrink couplings. Other patents of interest include U.S.
Pat. Nos.
5,660,534, 5,941,312, 6,065,537, 6,290,475, and 6,484,882, and Canadian
Patents
2,260,710 and 2,291,394.
[0006] An improved rod guide and method of molding a rod guide are hereinafter
disclosed.
Summary of the Invention
[0007] The present invention provides a pair of vanes, offset from one another
by
180 , and each vane wrapping approximately 180 around the rod guide. Vanes in
the art
that are shown and described in the references above have been variously
described as
"spiral" or "helical". The vanes in the present invention are neither spiral
nor helical
because the surfaces of the vanes extending radially outwardly from the body
of the rod
guide define two dimensional planar surfaces, i.e. flat planes, while the
corresponding
surfaces of the vanes shown and described in the art define curvilinear
planes.
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CA 02743742 2011-06-17
[0008] Thus, the vane thickness in the present invention varies from a maximum
at
each end of the vane to a minimum at a midway point along the vane. This shape
assists
in moving fluid up the production tubing when the guide is applied to a rotary
system,
such as a progressive cavity pump. This shape also enhances the erodable
volume of the
vanes at the extremities, while providing a less inhibited path for the flow
of fluid in
reciprocating applications.
[0009] These and other features and advantages of this invention will be
readily
apparent to those skilled in the art.
Brief Description of the Drawings
[0010] Other and further advantages and features of the invention will be
apparent to
those skilled in the art from the following detailed description of the
preferred
embodiments of the invention taken together with the accompanying drawings,
wherein
like reference numerals refer to like elements throughout. For the purpose of
illustrating
the invention, there is shown in the drawings embodiments which are presently
preferred;
it being understood, however, that this invention is not limited to the
precise
arrangements and instrumentalities shown.
[0011] Figure 1 is a front perspective view of a sucker rod with a rod guide
of the
present invention molded thereon a coupled to a down-hole pump.
[0012] Figure 2 is section view of the rod guide molded to a sucker rod.
[0013] Figure 3 is a front perspective view of the rod guide.
[0014] Figure 4 is a side perspective view of the rod guide of Figure 3
rotated by 90 .
[0015] Figure 5 is an end view of the sucker rod and rod guide of Figure 3.
[0016] Figure 6 is a section view of the rod guide taken along section lines 6-
6 of
Figure 4.
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CA 02743742 2011-06-17
Detailed Description of the Preferred Embodiments
[0017] Figure 1 depicts a presently preferred embodiment of a rod guide 10
with
wrapping vanes 11, in accordance with the teachings of the present invention.
While
only one rod guide is depicted, it is understood that many such rod guides,
spaced apart,
will be used in operation. The rod guide 10 is preferably molded onto a sucker
rod 12,
although the rod guide may be firmly affixed to the sucker rod in any manner
now known
or later developed. A pump 14 is coupled to the bottom end of the sucker rod
12 in a
manner well known in the art. The pump 14 is positioned within a casing 16 is
pump
fluids from the region surrounding the pump 14, up the casing, around the
various rod
guides 10, to the surface (not shown).
[0018] The plurality of rod guides are specifically adapted to operate within
one of a
number of standard casing diameters. Thus, there is a design clearance between
the
vanes 11 and an interior surface 18 of the casing. This keeps the sucker rod
centralized
within the casing and prevents the sucker rod from rubbing against the
interior surface of
the casing. The sucker rod, the rod guides, and the pump are coaxially aligned
along an
axis 20.
[0019] Figure 2 illustrates a cross section of a rod guide 10. The rod guide
10 defines
two wrapping vanes 11, as previously described. Each vane 11 an upper angled
edge 22
and a lower angled edge 24. The angled edges 22 and 24 reduce hydrodynamic
resistance to fluid flow by the rod guide. A conical end cap 26 tapers from
the upper
angled edge 22 down to the sucker rod. Similarly, a conical end cap 28 tapers
from the
lower angled edge 24. Note that the angled edge 22 provides a straight, non-
wrapping
vane segment between the end of the wrapping vane 11 and the conical end cap
26, and
the angled edge 24 provides a straight, non-wrapping vane segment between the
end of
the wrapping vane 11 and the conical end cap 28.
[0020] Figures 3 through 6 provide details of the structure of the rod guide
with
wrapping vanes of this invention. Figure 3 illustrates a front view of the rod
guide, while
Figure 4 shows the rod guide rotated by 90 . Figure 3 most clearly shows a
feature of
this invention, i.e. a flat, two-dimensional surface 30 on one side of a vane
11' and a flat,
two-dimensional surface 32 on the opposite side of the vane 11'. This flat
surface feature
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CA 02743742 2011-06-17
reduces fluid drag and simplifies the manufacturing process because the mold
is easier to
open with the flat surfaces.
[0021] As shown in Figure 4, the vane 11' and a vane 11" overlap along a
centerline
34 by roughly the width of a vane. Thus, each vane subtends roughly 180
around the
rod guide. The vane 11" also includes a flat, two-dimensional surface 36
extending
radially outwardly from an elongate, cylindrical body 38. The vane 11"
includes a flat,
two-dimensional surface 40 on the opposite side of the vane 11" (see Figure
6). With this
orientation, each vane defines a minimum thickness at a mid-point along the
vane and
maximum thickness at each end of the vane.
[0022] The principles, preferred embodiment, and mode of operation of the
present
invention have been described in the foregoing specification. This invention
is not to be
construed as limited to the particular forms disclosed, since these are
regarded as
illustrative rather than restrictive. While particular embodiments of the
present invention
have been illustrated and described, it would be obvious to those skilled in
the art that
various other changes and modifications can be made. The scope of the claims
should not
be limited by the preferred embodiments set forth in the examples, but should
be given
the broadest interpretation consistent with the description as a whole. It is
therefore
intended to cover in the appended claims all such changes and modifications
that are
within the scope of this invention.
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Representative Drawing