Note: Descriptions are shown in the official language in which they were submitted.
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GA~ TnRBIN~ M~T~
Field of the Invention
The invention relates to flow measurement devices and in
particular, to flow measurement devices using turbine meters as a
basis of the flow measurement.
Backqround of the Invention
Pipes are used to transport fluids of all sorts. Because *he
measurement of these fluids ~ 6 important, various types of fluid
measuring devices such as orifice plates, flow m~ters, turbine
meters, etc. are installed in-line with pipe sections. The use of
such a measurement for flow has been known since ancient times.
The present invention relates in general to turbine flow
meters. Turbine flow meters usually include a measuring chamber
having a flow guide in the front of such chamber, a measuring wheel
supported for rotation in the chamber and includes a magnetic
device which counts the blada turnings for blades mounted on the
hub of the measuring wheel.
The basic theory with regard to electronic turbine meters is
that fluid flow through the meter impinges upon the turbine blades
which are free to rotate about an axis along the Genter line of the
turbine housing. The angular (rotational) velocity of the turbine
rotor is directly proportional to the fluid velocity through the
turbine. The output of the turbine meter is measured by an
electrical pickup mounted in the meter body. The output frequency
of this electrical pickup is proportional to the flow rate. Also,
each electrical pulse is proportional to a small incremental volume
of flow. Thi~ incremental output is digital in form, and as such,
can be totalized with a maximum error of one pulse regardless ~f
the volume measured
Problems with existing turbine meters include a shift in the
meter factor curve over pressure change, rangeability over a larqe
range of pressures, large size, and the intrusion of dirt.
It is an object of the present invention to avoid the meter
factor curve change over the operating pressure of the meter, to
permit high flow rangeabili~y over a large range of pressure, such
as sub~tantially ambient to 1500 p.s.i. It is a further ob~ect o~
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the present invention to substantially reduce the size of the
meter. An additional object of the present invention is to inhibit
intrusion of dirt within the mechanism of the measuring wheels
supported for rotation in the chamber.
Summary of the Invention
The present invention discloses a turbine meter that is
suitable for either liquid or ga flow which can be installed for
use over a large pressure range, ~uch as, for example, ambient to
1500 p.s.i. whil~ maintaining a rangeability of, for example, 10:1
for ambient and 13:1 at 300 p.s.i. The present invention includes
a body or housing in which is contained a bilateral or s~mmetrical
configuration of a flow meter. The flow meter includes flow
diffusers at each end located in the flow passage of the body and
a detector at an interior wall of the body. A rotor is mounted on
a rotor shaft between the two flow diffusers. The rotor optimally
has twelve flat blades with optimal blade angles of 45~. A close
clearance is maintained between the blades and the interior of the
meter body which i5 optimally between .008" and .012"~ This i8
achieved through use of specific stif~ness of the blade which ~tems
from the use of a set o notches to form the blades having optimal
size for oval notches of width to height ra io of l.S to 2.0, ~uch
as ~169" x .094" for a two inch meter. The notches for most meters
would be oval in shape but at the extreme small and large si~es may
be other shapes~ such as tear drop. A magnetic pick-up i6 located
in the magnet housing immediately juxtaposed with the blades and
separated from~the blade by the int~rior wall o~ the body ~nd the
small clearance discussed above. The magnetic ~trength of 6uch
magnet located in the interior wall of the body is between 50 and
200 gauss. The rotor is mounted on the rotor shaft of the shaft by
bearings which are precision ball bearings for optimal results.
Blade thickness may vary between .01 and .0~5 of the rotor
diameter, such as .020" and .050" for a two inch meter while
maintaining the small size of the turbine meter.
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Brief Descri~tion of the Drawinq
For a f~rther understanding of the nature and objects of the
present invention, reference is made to the following drawing in
which like parts are given like reference numbers and wherein:
Figure 1 is a perspective view of the preferred embodiment of
the present invantion of the turbine meter;
Figure 2 i5 a side, partial cross-sectional view of the
preferred and alternate em~odiment of the present invention of the
turbine meter;
Figure 3 is a partial ~ide cross-sectional ~iew of a portion
o~ the preferred and alternate embodiment of Fig. 2;
Figure 4 is a plan vlew of the rotor ~haft of the preferred
embodiment of the present invention of the turbine meter;
Figure 5 is a cross-sectional view of the housing o~ the
preferred embodiment of the present invention of the turbine meter;
Figure 6 is a plan view of the rotor of the preferred
embodiment of the present invention of the turbine meter prior to
the formation of the blade configuration;
Figure 7 is an enlarged view of the portion of Figure 6
labelled "A";
Figure 8 ~s a side view of the rotor shaft lock washer of the
preferred embodiment of the present invention of the turbine meter;
Figure 9 is an exploded view of the alternate ~mbodiment of
the turbine meter of the present invention; and
Figure lO is an exploded view of the preferred embodiment of
the turbine me~er of the present invention.
Description of the Embodiments
A turbine meter 1 is shown in Figure 1 having sealing faces 10
for appropriate mounting in line. Turbine meter 1 further includes
interior opening ll surrounded by interior wall 12 o~ body 13.
Substantially identical diffusers 15 (Fig. 9) ara ~ounted in
opening 11 by spacers 20 which extend from diffusers 15 to an
interior hub 14 si~ed to fit in interior wall 12 o~ body 13. In
thls manner, as 6hown in Fig. 9, turbine meter 1 is symmetrical and
can be installed with either ~nd facing the upstrsam. Locator
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pins 16 hold hub 14 onto the interior wall 12. Retainer ring 17
engages groove 18 in wall 12 to lock hub 14 in place. Hubs 14 abut
interior shoulders 21 formed ln wall 12.
Referring to Figs. 2, 9 and 10, the diffusers 15 are shown in
two different configurations for contrast only. The alternate
configuration of diffuser 15 is designated by indicator 25 (see
Fig. 9), and the diffuser of the current design which is preferred
is indicated by indicator 30 (see Fig. 10). The difference between
the diffuser types is in the back edge 35, 40 of the diffusers 25,
30, respectively. The back edge 35 of diffuser 25 extends inwardly
much farther than the back edge 40 of diffuser 30.
As shown in Fig. 2, rotor shaft 45 is located such that its
longitudinal axis is substantially identical with the longitudinal
axis of the diffusers 15. The end6 50, 59 of rotor shaft 45 extend
into interior openings 55 of diffusers 15. Openings 55 have a
first bore 60 and a second bore 65 being substantially coaxial,
with bore 60 having a larger diameter than bore 65. Bores 60, 65
form a shoulder 70 therebetween.
Rotor shaft 45 is positioned to be substantially coaxial with
opening 55 by bearings 75 mounted in bore 60 and abutting
shoulder 70 at one end.
Rotor shaft 45 is shaped to include shoulders 80, 89.
Shoulder 80 is formed between extended shaft portlon 50 and raised
portion 85. Shoulder ~9 is formed between extended portion 59 and
raised portion 88. Rotor hub or shaft 45 also includes a central
extended diamet~er raised portion 100, one side 105 of which faces
extended portion 85, and the other side 110 of which faces extended
section 88. A bearing 75 also abuts shoulder 80 on the side of
face 105, and a second bearing 75 abuts shoulder 89 on the side of
face 110, thereby centering extended shafts 50, 59 of rotor
shaft 45 in opening 55. Because of bearings 75, rotor shaft 45 is
rotatably mounted within opening 55. Bearings 75 are preferably
precision ball bearings, instead of other bearings such as ~ewel
bearings. Precision ball bearings increase life at high speeds and
because of the remainder of the features of the preferred
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embodiment of the present invention, may be used at low flow rate~instead of jewel bearings. Jewel bearings and shaft assembly
operating at high revolution6 per minute do not last very long.
Rotor 120 i6 slidably mounted on enlarged shaft portion 88 by
sliding an opening 130 formed in the center of rotor 120 to ~it
over extended portions 59, 88.
Before the blades are formed in rotor 120, openings or
notches 140 are formed in a rotor 120 blanX comprising a circular
piece of metal. The notches 140 ~or most meters would be oval in
shape but at the extreme small and large sizes may be other ~hapes,
such as tear drop. For oval notches, t~e width to height ratio
would be preferably 1.5 to 2Ø Typically for a two inch meter the
dimensions would be .169" x .094". The notches 140 are located
symmetrically abaut the center of rotor 120 and radially displaced
from the center of rotor 120 by at least twenty-five percent of the
radius of the rotor 140. The interior end 160 and the opposing
exterior end 155 of notches 140 have a radius of curvature of, for
example, .047 inches for a two inch meter, and the outer end 155 of
each of the notches 140 includes a narrow channel 145, having a
width less than or equal to the material thic~ness of the blades,
for example, .025 incheR for a two inch meter, extending to the
outer circumference 150 of rotor 120. Typically, these notches 140
extend above the interior end curved portion 160, approximately
starting at .315 inches from the center ~for a two inch turbine
meter) of opening 130 and and at the beginnin~ of the exterior end
curved portion~155 which typically start .484 inches from thP
center (for a two inch turbine meter) of opening 130. The
material between openings 140 forms a shaft 170 leading to ~lat
blade portions 180 that extend from the exterior curved surface of
the exterior end 155 to the outer circumference 150 of rotor 120.
With regard to the thickness of the flat blade portions 180, blade
thickness is preferably in the range of .01 and .025 of the rotor
diameter, such as .020 inches to .050 inches for a two inch meter.
Shaft 170 permits the flexibility t~ twist the blade portion 180
relative ~o the interior of rotor 120.
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The blanks for the rotor 120 are not preferably formed by a
stamping die. The edges 350 of the fl~ blade portions 180 are
important to the performance of the turbine meter rotor 120 and
must be sharp. Sharp edges 350 are needed for liquid as well as
gas meters. Accordingly, with a aingle stage stamping die, care
cannot be taken as to what type of edge 350 can be provided, and
whether the edges 350 may have to be machined or have additional
stamping die stages to be sharp. For rotor 120 blank fabrication,
milling or laser cutting will be preferably used for sharpness of
leading and trailing edges 350 which effect linearity.
The openings or notches 140 effect the stiffnes~ of the flat
blade portion 180. Stiffness is important in a turbine meter to
minimize clearances and thus lower weight and size and cost of
substantially all components while maintaining accuracy. The
preferred notch 140 size ratio for an oval notch i5, ~8 set out
above, preferably 1.5 to 2.0, for example, .169 inches by .094
inches for a two inch turbine meter. In addition, because of the
extra stiffness, the number of blades may be increased. The ~lat
blade portions 180 may retain the stiffness because of notches 140
while increasing the number of flat blade portions 180, such as
above six flat blade portions, such as a range between ~ix to and
including twelve flat blade portions 180 with the optimal being
twelve flat blade portions 180. The larger number of blades in
combination with blade angle gives a greater resolution or
frequency to the signal produced by the turbine meter.
The blade~angles of flat blade portions 180 are turned in a
range between 30 and 60 with respect to the longitudinal axis of
the flow path, wit~ an optimal anyle of 45. The angle determines
to some extent the speed of the turning of the rotorj which as the
angle increases, the speed increa es. Slower turning decreases
resolution. However, speed decreases bearing life, and speed must
be chosen to optimize bearing life and resolution. The use of a
45~ angle yields the frequency which typically for a meter of the
preferred embodiment is 3000 hertz w~ich is believed to be
significantly higher than meters of the prior art. The 45 ~ngle
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requires the extra stiffness in order to be functional at maximumspeeds. In addition, lower angles are much less responsive at low
flows, and thus cut the rangeability of the meter at low flow rates
and low pressures.
Because of the stiffness, the length of ~he flat blade
portions 180 may be increased, thereby reducing the clearance
between the outer surface 150 of blade 180 and the interior
surface 350 of portion 320 of interior wall 12. Such clearance in
the preferred embodiment is in a range between .008 and .012
inches. The smaller this distance is; the closer the flat blade
portions 180 come to the pick-up coil 400 to obtain accurate
readings because at high pressures the thickness of portion 320
must be sufficient to withstand the high pressure in the interior
opening 11 of the body or housing 13. Further, the weight o~ the
flat blade portions 180 is important so that at low end flow rates,
magnetic drag is not experienced as greatly. In addition, at the
high end of the pressure range, flexing of the blades 180 can cause
collision with the interior surface 350 or alternately may open the
gap to surface 350 thereby decreasing signal strength. However,
because at the low end, magnetic drag is a factor, increasing
weight is not the solution to the stiffening, but the optimizing of
the notch 140 ~s reguired as discussed above.
Because of the size of the notch 140, the thickness o~ the
flat blade portions 180, the support of extension 100, a large fres
diameter of the flat blade portions 180 may be used, such as
preferable a diàmeter of five times the diameter of extension 100
to surface 240. Th~s causes signi~icant weight saving.
Rotor 120 i6 attached to enlarged diameter portion 100 by
small welds 200 or with special bonding agents such that one ~ide
of rotor 120 securely abuts surface 110. The other ~ide of
rotor 120 abuts a lock washer 210 which is fastened to rotor 120 by
a small weld 230 or with special bonding agents~ Thus, lock
washer 21D and rotor 120 are rotatably mounted about the center
axis of opening 55. Preferab~y resistance welding would be used in
manufacture instead of spot welding. The welding 200, 230 o~ the
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rotor 120 shaft assembly al~o improves the ttachment of the
rotor 120. The welding 200, 230 eliminates potential problems with
other type of bonding agents, ~uch as Loctite~, although Loctite~
may be used as a bonding agent. The problems of other type of
bonding agents would include improper assembly procedures and part
cleaning which are necessary for a bonding of this type to perform
the appropriate tasks. The welds 200, 2~0 or other welding
techniques, unlike other techniques, can be vi6ually inspected to
determine acceptability, whereas incorrect proc~dures of as6embly
and bonding cannot be detected until the e~uipment falls apart.
Because the meter 1 may be used in bi-directional flow, the
welding 200, 230 also becomes important because thrust forces on
the rotor 120 are transmitted to the lock washer 210 in the reverse
flow mode. Further, a welded rotor 120 may increase the maximum
temperature limit of the meter 1. Care should be taken to insure
that a flat surface of rotor 120 abuts the ~lat surface 110 of
ext~nsion 100.
As shown in Figs. 2 and 3, the preferred diffuser 25 includes
interior surface 35 which extend substantially oYer the entire
outer circumference 240 of extension 100. Optionally, as shown in
Fig. 2, a machine cut 2SO into surface 35 may also be formed, but
surface 35 would still cover outer circumference 240. The
clearance between outer circumference 240 and the interior surface
250 o~ extension 35 is very close. Thus, dust would tend not to
leak into the bearing 75 area of the mounting of the rotor 120 and
rotor shaft 45 ~ith the preferred di~users 25. In addition, these
surfaces will tend to capture the rotor 120 should the bearings
fail, preventing damage to the interior 11 of body or housing 13.
While not shown in Fig. ~, if a diffuser 25 is used ln place of
diffuser 30, it would substantially cover the outer circumference
of lock washer 210.
Accordingly, the diffuser modi~cation will hold the rotor 12Q
in place longer aftex failure of and bearinqs 75, giving some
indication of flow for a longer period ~f time and preventinq the
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rotor 120 from damaging the bore or interior wall 12 oP body 13
and, especially the thin wall 320 under the ~oil 400.
The housing 13 includes a pressure tap 300 centrally located
for which a pressure transducer and transmitter may be attached to
measure the pressure in the interior 11 close to the flat blade
portions 180.
~ he housing or body 13 further includes an indented exterior
portion 310 that houses the pick-up coil 400 graphically depicted
in Fig. 1 and shown in Figs. 9 and 10 which, except as described
below, is standard in the art. The pick-up coil 400 includes coils
typical of the art which are wound and placed within opening 330.
In the preferred embodiment of the present inventlon, because the
blades are so close to the interior wall 350 of the housing 13, and
there are so many flat blade portions 180, magnetic strength of th~
pick-up coil 400 should be optimized to improve meter performance
at low flow rates and avoid magnetic drag. The magnetic trength
of the p~ck-up coil 400 is preferably between 50 and 200 gauss as
a function of the number of windings and th~ wire size of the pick-
up coil 400. The thickness 320 below the opening 330 for the pick-
up coil 400 must be sufficient to contain the pressure within the
interior 11 of the housing or body 13.
In use, after assembly, flow may be introduced on either
diffuser 25 of meter 1 which will deflect the flow against the
surface o~ flat blade portions 180 facing the flow. The
impingement of the flat blade portions 180 cause flat blade
portions 180 t~ rotate around the axis of rotor shaft 45. As the
flat blade portions 180 rotate under the pick-up coil 400 located
over surface 320, the presence of the flat blade portions 180 of
the rotor 120 will be detected as pulses having a width dependant
on the time that sur~ace 150 is ~uxtaposed in whole or in part with
pick-up coil 400. The pulses are subject to 6ignal smoothlng and
shaping and amplification and other conditioning by
preamplification and ultimately used for ~low rate and/or flow
volume measurement.
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The shift on the meter curve as a function of line pressure is
dependent on the ratio o* the total drag on the rotor to the
turning mcment on the rotor. Major contributors to the drag are
mechanical, frictional, viscous, and magnetic. At the same flow
rate with the increasing density of the fluid, the turning moment
al~o increaseR. For a meter with a mechanical drive, the main
source o~ drag is Prom the drive. TherePore, a shift of the meter
curve occurs at a higher line pressure. With magnetic pick-up, the
dra~ is significantly reduced. Hence, the shi~t on the meter curve
occurs at a much lower line pressure than that of a turbine meter
with mechan~cal drive. For the miniature turbine meter 1 a
significant contribution of drag i~ from the magnetic field of the
pick~up coil. The combination of magnetic pick-up coil strength,
choice of bearing, blade thickness, blade angle, and blade
clearance has a synergistic effect to minimize the shift of the
meter curve to line pressures as low as ambient condition. The
curve shift is insignificant and included within the accuracy of
the meter.
The embodiments set forth herein are merely illustrative and
do not limit the scope of the invention or the details therein.
For example, siæing will cause adjustments in various dimensions.
It will be appreciated that many other modifications and improve
ments to the disclosure herein may be made without departing ~rom
the scope of the invention or the inventive concepts herein
disclosed. Because many varying and different embodiments may be
made within the scope of the inventive concept h~rein taught,
including equivalent structures or materials hereafter thought of,
and becau~e many modifications may be more in the embodiments
herein detailed in accordance with the descriptive requirements o~
the law, it is to be understood that the details herein ~re to be
interpreted as illustrative and not in a limiting sense.
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