U.S. patent application number 16/768933 was filed with the patent office on 2021-07-15 for coriolis flow sensor assembly.
The applicant listed for this patent is GE Healthcare Bio-Sciences AB. Invention is credited to Philipp Lang, Jens Ruetten, Charles E. Seeley.
Application Number | 20210215520 16/768933 |
Document ID | / |
Family ID | 1000005492925 |
Filed Date | 2021-07-15 |
United States Patent
Application |
20210215520 |
Kind Code |
A1 |
Lang; Philipp ; et
al. |
July 15, 2021 |
Coriolis Flow Sensor Assembly
Abstract
Provided is a Coriolis flow sensor assembly that includes a
fluid flow assembly, including a flow tube, wherein the fluid flow
assembly is configured to provide a flow path through the flow
tube. The flow tube has at least one region of increased stiffness,
which may be a result of a structural support component coupled to
the flow tube. In another embodiment, the increased stiffness is
caused by integral properties of the flow tube.
Inventors: |
Lang; Philipp; (Garching,
DE) ; Ruetten; Jens; (Garching, DE) ; Seeley;
Charles E.; (Niskayuna, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE Healthcare Bio-Sciences AB |
Uppsala |
|
SE |
|
|
Family ID: |
1000005492925 |
Appl. No.: |
16/768933 |
Filed: |
December 4, 2018 |
PCT Filed: |
December 4, 2018 |
PCT NO: |
PCT/EP2018/083554 |
371 Date: |
June 2, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15832473 |
Dec 5, 2017 |
10422678 |
|
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16768933 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01F 1/8418 20130101;
G01F 1/8413 20130101; G01F 1/8472 20130101; G01F 1/849
20130101 |
International
Class: |
G01F 1/84 20060101
G01F001/84 |
Claims
1. An assembly comprising: a structural support component
configured to receive a flow tube, the flow tube being configured
to provide a flow path for a fluid; and a mechanical drive assembly
configured to drive an oscillation of the flow tube and the
structural support component while fluid is flowing through the
flow path, wherein oscillation of the flow tube in at least one
plane is decreased when the flow tube is coupled to the structural
support component.
2. The assembly of claim 1, wherein the structural support
component comprises a body that extends away from the flow tube
when the flow tube is coupled to the structural support component,
wherein a first portion of the body extends away from the flow tube
a first distance and wherein a second portion of the body extends
away from the flow tube a second distance, the first distance being
greater than the second distance.
3. The assembly of claim 1, wherein the structural support
component forms a partial annulus about the flow tube when coupled
to the flow tube.
4. The assembly of claim 1, wherein the structural support
component extends along an entire length of the flow tube when
coupled to the flow tube such that the flow tube is in direct
contact with at least a portion of the structural support component
along the entire length.
5. The assembly of claim 1, wherein the structural support
component is different in a first and a second region relative to a
third region, wherein the third region is flanked by the first
region and the second region.
6. The assembly of claim 1, wherein the flow tube is configured to
be reversibly coupled to the structural support component.
7. The assembly of claim 1, wherein the structural support
component comprises a plurality of ribs distributed along its
length, wherein the plurality of ribs are configured to receive the
flow tube.
8. The assembly of claim 1, wherein the structural support
component comprises at least one fin that extends in a lateral
direction away from the flow tube.
9. The assembly of claim 1, wherein the flow tube coupled to the
structural support component.
10. The assembly of claim 9, wherein the flow tube comprises a
first location having increased stiffness relative to a second
location of the flow tube.
11. An assembly comprising: a flow tube configured to provide a
flow path through the flow tube, wherein the flow tube has a first
region and a second region, the first region and the second region
both having a greater stiffness than a third region; and a
mechanical drive assembly configured to drive an oscillation of the
flow tube while fluid is flowing through the flow path.
12. The assembly of claim 11, wherein the flow tube is formed from
a material having variable wall thickness and wherein a first wall
thickness of the first region and a second wall thickness of the
second region are greater than a third wall thickness of the third
region.
13. The assembly of claim 11, wherein the first region or the
second region is 25% or less of a total length of the flow
tube.
14. The assembly of claim 11, wherein the third region is longer
than the first region and the second region.
15. The assembly of claim 11, wherein the third region is flanked
by the first region and the second region.
16. The assembly of claim 11, wherein the first region, the second
region, and the third region are arranged along a flow axis of the
flow path.
17. The assembly of claim 11, wherein the flow tube defines a
generally straight flow path.
18. The assembly of claim 11, wherein the flow tube is
disposable.
19. The assembly of claim 11, further comprising a structural
support component reversibly coupled to the flow tube, wherein the
structural support component couples to the flow tube to result in
the greater stiffness of the first region and the second region
relative to the third region.
20. The assembly of claim 19, wherein said stiffness is a bending
stiffness.
21. A system comprising: a fluid flow assembly, the fluid flow
assembly comprising a flow tube, wherein the fluid flow assembly is
configured to provide a flow path through the flow tube, wherein
the flow tube is formed from a material having a first stiffness at
a first location and a second stiffness at a second location, the
first stiffness being greater than the second stiffness; a
mechanical drive assembly configured to drive an oscillation of the
flow tube while fluid is flowing through the flow path; and a
sensor configured to sense the oscillation of the flow tube and
generate a signal indicative of the oscillation.
Description
BACKGROUND
[0001] The present disclosure relates generally to Coriolis flow
sensors. More specifically, the present disclosure relates to a
Coriolis flow sensor assembly with structural modifications that
improve sensitivity of the measurements performed by the Coriolis
flow sensor.
[0002] Accurate measurements of the properties of fluids delivered
through flow systems is important for a variety of applications,
such as in bioprocessing systems and oil and gas pipelines. One
technique for measuring the properties of fluids is by using the
flow rate. This permits measurements to be performed during fluid
delivery, which is advantageous for reducing associated operating
costs. That is, active flow systems may be operational during
measurement. Flow rates may be measured either as volumetric flow
rates or mass flow rates. Volumetric flow rates are accurate if the
density of the fluid is constant; however, this is not always the
case as the density may change significantly with temperature,
pressure, or composition. As such, mass flow rates are typically
more reliable for measuring fluid flow. One method for measuring
mass flow rates is through a Coriolis flow sensor (e.g., a flow
meter). In general, a Coriolis flow sensor measures mass flow rates
via the Coriolis force that results from the fluid as it moves
through an oscillating tube.
BRIEF DESCRIPTION
[0003] Certain embodiments commensurate in scope with the
originally claimed subject matter are summarized below. These
embodiments are not intended to limit the scope of the claimed
subject matter, but rather these embodiments are intended only to
provide a brief summary of possible embodiments. Indeed, the
disclosure may encompass a variety of forms that may be similar to
or different from the embodiments set forth below.
[0004] Provided herein is an assembly including a structural
support component configured to receive a flow tube, the flow tube
being configured to provide a flow path for a fluid. Further, the
assembly includes a mechanical drive assembly configured to drive
an oscillation of the flow tube and the structural support
component while fluid is flowing through the flow path, and wherein
oscillation of the flow tube in at least one plane is decreased
when the flow tube is coupled to the structural support
component.
[0005] Provided here in is an assembly including a flow tube
configured to provide a flow path through the flow tube, wherein
the flow tube has a first region and a second region, the first
region and the second region both having a greater stiffness than a
third region. Further, the assembly includes a mechanical drive
assembly configured to drive an oscillation of the flow tube while
fluid is flowing through the flow path.
[0006] Provided herein is a system including a fluid flow assembly,
the fluid flow assembly comprising a flow tube, wherein the fluid
flow assembly is configured to provide a flow path through the flow
tube, wherein the flow tube is formed from a material having a
first stiffness at a first location and a second stiffness at a
second location, the first stiffness being different than the
second stiffness. Further, the system includes a mechanical drive
assembly configured to drive an oscillation of the flow tube while
fluid is flowing through the flow path. Even further, the system
includes a sensor configured to sense the oscillation of the flow
tube and generate a signal indicative of the oscillation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features, aspects, and advantages of the
present disclosure will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0008] FIG. 1 is a block diagram of a Coriolis flow sensor system
in accordance with the present disclosure;
[0009] FIG. 2 is schematic diagram of oscillations of Coriolis flow
sensor assemblies in operation in accordance with the present
disclosure;
[0010] FIG. 3 shows the Coriolis phase shift of a flow tube having
a uniform stiffness;
[0011] FIG. 4 shows a comparison of phase shifts of flow tubes of a
having uniform stiffness or a variable stiffness in accordance with
the present disclosure;
[0012] FIG. 5 shows phase shifts of Coriolis flow sensor assemblies
having flow tubes with uniform or variable stiffness in accordance
with the present disclosure;
[0013] FIG. 6 is an illustration of implementations of a flow tube
of a Coriolis flow sensor assembly having variable stiffness in
accordance with the present disclosure;
[0014] FIG. 7 is a schematic illustration of lateral and vertical
oscillation of a flow tube of a Coriolis flow sensor assembly in
accordance with the present disclosure;
[0015] FIG. 8 shows phase shifts of a structural support component
having a dorsal fin in accordance with the present disclosure;
[0016] FIG. 9 shows the lateral and drive oscillation mode of a
structural support component having a dorsal fin in accordance with
the present disclosure;
[0017] FIG. 10 shows various modes of oscillation of a flow tube of
a Coriolis flow sensor in accordance with the present
disclosure;
[0018] FIG. 11 shows the Coriolis phase shift sensitivity of a flow
tube coupled to a structural support component having lateral and
vertical fins in accordance with the present disclosure;
[0019] FIG. 12 shows the Coriolis phase shift sensitivity of a flow
tube with a structural support component having dual fins in
accordance with the present disclosure; and
[0020] FIG. 13 is an illustration of a structural support feature
in accordance with the present disclosure.
DETAILED DESCRIPTION
[0021] One or more specific embodiments of the present disclosure
will be described below. In an effort to provide a concise
description of these embodiments, all features of an actual
implementation may not be described in the specification. It should
be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0022] When introducing elements of various embodiments of the
present disclosure, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
[0023] Coriolis flow sensors are useful in numerous applications
that involve fluid delivery, such as bioprocessing systems. In
general, a Coriolis flow sensor operates by measuring a phase shift
of one or more oscillating flow tubes that results from a Coriolis
force. It is beneficial to provide a Coriolis flow sensor designs
that increases the effect of the Coriolis force, which in turn
results in an increased mass flow sensitivity and sensing amplitude
(high signal to noise ratio: SNR). Certain Coriolis flow sensors
are often used in conjunction with a continuous tubing that is
uniform along its length.
[0024] Certain approaches to implementing Coriolis flow sensors aim
to magnify the flow sensitivity by shaping the tubing, and the
corresponding fluid flow path, into favorable geometrical forms.
However, in addition to improving the sensitivity of the Coriolis
flow sensor measurement, the Coriolis flow sensor should also be
robust against environmental disturbances that may impact the
accuracy of sensor readings. Many approaches to modifying the
geometric form of the tubing often result in large tubing loops
that have no advantage in zero point stability because external
disturbances are also magnified (which in turn decrease sensor
accuracy). Thus, the effective signal to noise ratio may remain the
same. Further, these configurations also take up additional space
in a fluid flow system, and looped geometric form modifies the
fluid flow path; which influence pressure loss, flow velocity,
shear rate, trappings, draining, and abrasion.
[0025] The present disclosure is directed to a Coriolis flow sensor
assembly with an improved signal to noise ratio. The assembly may
include a flow tube (e.g., a disposable flow tube) with features
that reduce loss of oscillation forces. In an embodiment, the
Coriolis flow sensor assembly may include a flow tube with variable
stiffness along its length. As discussed in detail below, variable
stiffness along the flow tube improves the performance of the
Coriolis flow sensor assembly by increasing the Coriolis phase
shift of the oscillating tube and by reducing contributions from
other oscillation modes (e.g., structural oscillation modes) to the
oscillation imparted by the mechanical drive assembly. In certain
embodiments, the variable stiffness along the flow tube results
from modifications of the flow tube (e.g., varying the inner wall
thickness or varying the material of the flow tube alone its
length). In other embodiments, the variable stiffness along the
flow tubes is a result of external structural support components
that impart stiffness to certain axes that include oscillation
modes that tend to contribute to sensor noise. Further, the
incorporation of the variable stiffness features permits the
Coriolis flow sensor assembly to be used without looped or other
geometric flow tube structures. For example, the disclosed
techniques may be applied to a Coriolis flow sensor assembly with a
straight or unlooped flow tube, to reduce or eliminate certain
disadvantages associated with conventional looped sensor flow tubes
(e.g., taking up space, effects of modifying the fluid flow path).
That is, the signal to noise ratio improvements achieved via the
disclosed techniques are achieved with a straight or unlooped flow
tube. However, it should be understood that the disclosed
techniques may also be used in conjunction with flow tubes with
looped or other geometric shapes to augment signal to noise ratio
improvements in such assemblies.
[0026] Turning now to the figures, FIG. 1 is a diagram illustrating
an embodiment of the Coriolis flow sensor system 10. The Coriolis
flow sensor system 10 includes electronics circuitry 12 coupled to
a sensor assembly 14. The sensor assembly 14 may include a flow
tube and one or more features that provide increased stiffness to
the flow tube.
[0027] In one embodiment, the sensor assembly 14 includes a fluid
flow assembly 18 that provides variable stiffness along a flow tube
forming a fluid flow path. For example, the sensor assembly may
include a variable stiffness flow tube 20 for retaining a fluid 22.
In another embodiment, the variable stiffness flow tube 20 may be
coupled to a structural support component 24 that provides and/or
augments the variable stiffness by constraining the movement of the
flow tube 20 in certain axes. In certain embodiments, the variable
stiffness may be achieved via features integral to the flow tube 20
itself, and the flow tube 20 may be used in conjunction with the
system 10 with or without the structural support component 24. In
other embodiments provided herein, the structural support component
may be used in conjunction with a uniform stiffness flow tube
(i.e., a flow tube not including the variable stiffness features
disclosed herein or a flow tube having a generally constant
stiffness along its length, such as the flow tube 17 as shown in
FIG. 2)
[0028] Additionally, the sensor assembly 14 may, in certain
embodiments, include one or more sensors 26 and one or more
actuators 16. It would be appreciated by those skilled in the art
that one or more components of the sensor assembly 14 may be
configured as disposable parts, and that other components may be
configured as re-usable resident parts. To that end, in
implementations in which certain components are disposable, the
disposable components may be separable (e.g., by an operator using
appropriate tools or by hand) from the resident parts. For example,
at least one of the flow tubes 20, the one or more actuators 16, or
the one or more sensors 26 may be disposable parts, and other parts
are configured as reusable resident parts. It would be appreciated
by those skilled in the art that the disposable part(s) may be
replaced at very low cost in intervals governed by the specific
process needs. In addition, in some implementations, the flow tube
20 may be changed), without the need for replacement of the entire
Coriolis flow sensor. The disposable-part sub-system allows
obtaining high accuracy measurements, reusing of part of the
Coriolis flow sensor system 10, provides a flexibility for
single-use applications, and achieves cost and material
savings.
[0029] Referring to FIG. 1, in some embodiments, the flow tube 20
may be coupled with a mechanical oscillator 28 or form an assembly
with the mechanical oscillator 28 and, thus, take the form of a
rigid, oscillating tubing during operation of the mechanical
oscillator 28. The one or more actuators 16 are used to induce
oscillations of an appropriate amplitude over a required frequency
range in the fluid 22 through the mechanical oscillator 28 and the
flow tube 20. The mechanical oscillator 28 and the actuator 16 are
referred to collectively as the mechanical drive assembly 30. The
one or more sensors 26 are configured to provide signals indicative
of a Coriolis response caused by the fluid 22 flowing through the
flow tube 20. The one or more sensors 26 may include, for example,
electromagnetic sensors, or optical sensors, and associated
components.
[0030] The flow tube 20 may be configured as a conduit with an
internal passage that permits fluid flow and may be formed in a
shape including, but not limited to single, dual or multi loop
configurations, split flow, straight tube, counter- or co-flow
configurations. In some implementations, the flow tube 20 is made
from, for example, a polymer whose influence on the oscillation
modes (harmonic frequencies) of the mechanical oscillator is not
dominant. In some other examples, the flow tube 20 is made of
metal. In yet other examples, the flow tube 20 is made of glass.
The flow tube material, in some examples, is tailored to specific
requirements of the bioprocessing application, such as temperature,
pressure, and the characteristics of the fluid to be measured
(e.g., corrosivity). Further, the flow tube 20 may be implemented
with wall thickness or material features to promote the variable
stiffness along its length as provided herein. The flow tube 20 may
be arranged to permit in-line fluid flow sensing for a fluid
processing system. Accordingly, the flow tube may be in fluid
communication with fluid conduits of a larger fluid processing
system.
[0031] The Coriolis flow sensor system 10 also includes electronics
circuitry 12 coupled to the sensor assembly 14. The electronics
circuitry 12 includes drive circuitry 32 to trigger the one or more
actuator(s) 16 to generate oscillations in the flow tube 20 of the
desired frequency and magnitude. The Coriolis flow sensor system 10
further includes sensor circuitry 34 to receive the Coriolis
response from the flow tube 20. The electronics circuitry 12
further includes a processor 36 to process the Coriolis response
signals received from the sensors 26 to generate one or more
measurements representative of one or more properties of the fluid.
These measurements are displayed via a user interface 38. The
electronics circuitry 12 also includes a memory 40 to store the
measurements for further use and communication, to store data
useful for the drive circuitry 32, and the sensor circuitry 34.
[0032] In operation, the electronics circuitry 12 triggers the one
or more actuator(s) to generate oscillations in the flow tube 20,
which are transferred to the fluid 22. Due to these oscillations,
the Coriolis response (vibration amplitude and phase) is generated
in the fluid and is sensed by the sensors 26 through the flow tube
20. The sensed Coriolis response signal from the sensors 26 are
transmitted to the electronics circuitry 12 for further processing
to obtain the measurements of the one or more properties of the
fluid including fluid flow.
[0033] The system 10 may be used to assess fluid characteristics in
any fluid flow system. As disclosed, the fluid characteristics may
be assessed during operation of a variety of manufacturing and/or
fluid flow processes. Some applications for the system 10 described
herein include fabrication of wafers in semi-conductor industry,
and medical applications that involve use of organic fluids. Some
of these are high purity applications, and use of flow tube 20 made
of for example polymer, or other chemically inert material is
advantageous in such applications. In some other applications, a
flow tube 20 formed of electrically inert and low thermal
conductivity material like glass is advantageous.
[0034] FIG. 2 illustrates oscillation diagrams 42, 44, and 46 of
example oscillation modes. The oscillation diagram 42 shows a
uniform stiffness flow tube 17 relative to oscillation diagrams 44
and 46, which show fluid flow assemblies 18 with flow tubes 20
having variable stiffness that may be used in conjunction with the
Coriolis flow sensor system 10 as provided herein. As shown, each
flow tube 20 may be coupled to a mechanical oscillator 28 that
drives the oscillation of each flow tube 20. The system 10 may
include two sensors 28 that sense the oscillation.
[0035] The flow tubes 20 shown in oscillation diagrams 44 and 46
include one or more regions 23 of increased stiffness positioned
along to the flow tube 20. The regions of increased stiffness are
relative to regions 25 that are less stiff. In certain embodiments,
the increased stiffness may result from one or more of the flow
tube 20 being formed from different materials in the one or more
regions 23 relative to the regions 25 that are less stif, increased
wall thickness of the flow tube 20 in the regions 23 relative to
wall thickness of the flow tube 20 in the less stiff regions 25, or
via one or more structural support components 24 (e.g., as shown in
FIG. 7) coupled to the flow tube.
[0036] In operation, a force 48 is applied to approximately the
center 31 of the flow tube 20, as measured along the length or
fluid flow axis (e.g., as shown by the flow arrow 52) and which may
correspond to half the distance between a fluid entry point 27 and
a fluid exit point 29 of the flow tube 20, by the mechanical
oscillator 28 of the mechanical drive assembly 30. The force 48
results in a typical drive deflection shape 50. Upon a flow 52
(e.g., of fluid 22, shown flowing in the direction of the arrow
52), a Coriolis force distribution 54 is exerted on the flow tube
20, resulting in a rotation 56 of the flow tube. The combination of
the Coriolis force distribution 52 and the drive deflection shape
50 is a Coriolis deflection shape 58.
[0037] The Coriolis deflection shape, w, depends on the Coriolis
force distribution 52 and the bending stiffness of the flow tube. A
Coriolis phase shift, .DELTA.t, is determined by a relationship
between the drive deflection shape 48, .nu., of the flow tube and
Coriolis deflection shape 58, w at a specific frequency, f:
.DELTA. .times. t = - 1 f .times. tan - 1 ( w v ) ##EQU00001##
[0038] As discussed above, Coriolis phase shift is used to measure
properties of the fluid and the rate of fluid flow. In general, a
greater Coriolis phase shift results in a higher sensitivity of
measurement. The Coriolis phase shift can be determined with the
relationship of drive displacement to Coriolis displacement.
[0039] A variable bending stiffness along the oscillator axis
(e.g., in the direction of the force 48) influences at both the
drive deflection shape 48 and the Coriolis force distribution,
resulting in a modified Coriolis deflection shape. Moreover, the
variable bending stiffness shifts the Coriolis force distribution
along oscillator axis, which shifts the Coriolis force distribution
54 towards oscillation maximum. Oscillation diagrams 44 and 46
illustrate how the Coriolis deflection shape 52 changes with
variable stiffness distributions imparted by the regions 23 of
increased stiffness. Schematic 44 illustrates that increased
stiffness at the ends of the oscillator axis (i.e., at the fluid
entry point 27 and the fluid exit point 29), shifts the Coriolis
force distribution 64 maximum towards the center of the oscillator.
Hence, the Coriolis force cause a higher Coriolis movement in the
sensed area, which results in an increased phase shift. As shown in
schematic 48, when the region or regions 23 of increased stiffness
are positioned at the center 31 of the flow tube, the drive
deflection shape 48 may be flattened at the center. Thus, the
Coriolis force distribution 52 and Coriolis deflection shape are
defocused and shifted towards the rotation axis, resulting in less
Coriolis phase shift relative to homogeneous bending stiffness or
increased bending stiffness near to the rotation axis. Accordingly,
in certain embodiments, the flow tube 20 is provided with one or
more regions 23 of increased stiffness that are positioned adjacent
to the fluid entry point 27 and/or the fluid exit point 29 of the
flow tube 20. Further, the flow tube 20 may have one or more
regions 23 of increased stiffness that are positioned to avoid or
exclude the midpoint 31 of the flow tube 20 (e.g., the midpoint
between the fluid entry point 27 and the fluid exit point 29). The
flow tube 20 may have one, two, or any number of regions 23 of
increased stiffness.
[0040] FIG. 3 shows experimental results for assessing Coriolis
phase shift in conjunction with a uniform stiffness flow tube 17
with a constant stiffness and a corresponding graph 70 of the
Coriolis phase shift sensitivity. An image 72 shows the
experimental setup for determining the Coriolis phase shift
sensitivity (e.g., Coriolis phase shift based on flow rate) with
the flow tube coupled to a mechanical drive assembly 30. The graph
70 displays the Coriolis phase shift versus the scale flow rate
(kg/min). Points 74 represent repeated measurements of the Coriolis
flow sensor having flow tube 20 illustrated in image 72. For this
configuration, the measured Coriolis phase shift ranges from
approximately 2 to 10 .mu.s from a flow rate up to 10 kg/min. The
measured Coriolis phase shift of flow tube shown in image 72 is 4
.mu.s based on a 4.7 kg/min flow and a 150 Hz drive
oscillation.
[0041] FIG. 4 is a schematic illustration comparing phase shifts
between a uniform stiffness flow tube 17 and a variable stiffness
flow tube 20 having the variable stiffness (e.g., along the axis
78), in accordance with the present disclosure. Flow tube 17 has a
continuous stiffness distribution and has a phase shift of 4 .mu.s
based on a 4.7 kg/min flow and a 150 Hz drive oscillation,
calculated using Finite Element Analysis (FEA). The phase shift of
flow tube 20 is 37 .mu.s based on a 4.7 kg/min flow and a 150 Hz
drive oscillation is, calculated using FEA.
[0042] FIG. 5 shows the uniform stiffness flow tube 17 relative to
various implementations of the variable stiffness flow tube 20
(illustrated as flow tubes 82, 84, 86, and 88) with a variable
bending stiffness distributions with corresponding Coriolis phase
shift sensitivities that calculated using Finite Element Analysis
(FEA). Each flow tube 17, 20 has a variable bending stiffness
across the length 90 (e.g., flow axis 91). The magnitude of the
bending stiffness of each flow tube 17, 20 is related to the height
92 along the axis 94 (e.g., vertical axis). For example, flow tube
82 has two regions of greater bending stiffness within
approximately the first 25% and last 25% of the length of each flow
tube. Flow tubes 84, 86, and 88 show variable (e.g., graded)
stiffness along the length of each flow tube.
[0043] The phase difference, .DELTA.t, of each flow tube 17, 20
(82, 84, 86, and 88) was calculated using Finite Element Analysis
(FEA) simulations based on a constant flow of 4.7 kg/min and a flow
tube inner diameter (ID) of 6.3 mm. The lengths of each arrow 96
(several are annotated in FIG. 4) represents the magnitude of the
Coriolis force on the flow tubes 17, 20 (82, 84, 86, and 88). The
calculated phase difference of flow tubes 17, 20 (82, 84, 86, and
88) is 4.5, 8.1, 14.3, 12.4, 4.4, 2.9 .mu.s, respectively. Each
calculated phase difference is measured at the same position for
each flow tube. The flow tube 82 had the highest phase difference
of the flow tubes represented herein (e.g., a phase difference of
14.3 .mu.s), which indicates it has the highest sensitivity. Thus,
FIG. 5 shows that there is a distribution of stiffness across the
flow tube 20 that results in the greatest performance (e.g., high
flow sensitivity). While the flow tubes 17, 20 (82, 84, 86, and 88)
shown in FIG. 5 are all generally straight about the flow axis, it
should be appreciated by one of ordinary skill in the art that the
effect of improved performance with a modified stiffness of the
flow tubes 20 extends to flow tubes of other geometries as provided
herein. Accordingly, as provided herein, the flow tube 20 may be
formed having a lower (e.g., minimum) stiffness region 25 that
extends across the midpoint 31 and that is flanked by relatively
higher or increased stiffness regions 23. The increased stiffness
regions 23 of the flow tube 20 may have stepped or nonconstant
thickness such that individual locations within the increased
stiffness region or regions 23 have increased stiffness relative to
the lower stiffness region 25 but may have different stiffness
relative to other locations in the increased stiffness region or
regions 23. It should also be understood that other implementations
are contemplated. For example, the flanking increased stiffness
regions 23a and 23b may have the same stiffness as one another or
may have different stiffness relative to one another while being
nonetheless higher in stiffness than the lower stiffness region 25.
Further, the increased stiffness regions 23a and 23b may be the
same length or different lengths. In addition, the increased
stiffness region 23a or 23b may be eliminated in certain
implementations. In one embodiment, the increased stiffness region
23 (e.g., 23a and/or 23b) may be about 5-30% of a total length of
the flow tube 20, as measured from the fluid entry point 27 to the
fluid exit point 29. The lowest stiffness region 25 may be about
20-80% (e.g., 20-30%, 20-40%, 20-50%, 30-60%) of a total length of
the flow tube 20, as measured from the fluid entry point 27 to the
fluid exit point 29. In addition, the lowest stiffness region 25
may be symmetrical about the midpoint 31 or may be asymmetric with
respect to the midpoint 31. Regardless of the specific
configuration, the flow tube 20 may be configured such that a first
location on the flow tube has a different stiffness (e.g.,
determined from geometry, harmonic motion, or Young's modulus) than
a second location spaced apart from the first location along the
fluid flow path.
[0044] FIG. 6 shows cross-sectional views of several exemplary
implementations for a variable stiffness flow tube 20 with variable
stiffness along the length of the flow tube 20 for use in
conjunction with the Coriolis flow sensor system 10 as provided
herein. Flow tube 100 has a gradually varying wall thickness 102
along the length 90 that imparts the increased stiffness. While
flow tube 100 illustrates a linear variation in thickness 102, any
grade change of thickness is permissible. In general, the flow tube
has a greater thickness at locations 104 and 108 relative to
location 106. Flow tube 109 has increased stiffness at the ends 110
resulting from periodically-spaced increased thickness regions 112,
e.g., ribs of increased thickness that are distributed at locations
to promote higher signal to noise ratios. Flow tube 114 illustrates
variable stiffness achieved through variable material composition
of the flow tube. For example, the center of the flow tube is made
of a first material 116 which is flanked by material 118 and
material 120. Materials 118 and 120 may be the same or different
materials. The relative stiffness of materials 116, 118, and 120
may differ with regards to the desired variable stiffness. For
example, materials 118 and 120 may be stiffer than material 116 to
achieve an increased stiffness on the ends. Such variation in
thickness or materials may be achieved using appropriate extrusion
parameters when manufacturing the flow tube 20. Further, the
variable stiffness of the flow tube 20 may be achieved by providing
additives or stiffeners (e.g., additive particles, wire) to the
material of the flow tube 20 in the increased stiffness region(s)
23 and not in the lower stiffness region 25. In certain
embodiments, any change in thickness or material composition may be
about the entire circumference of the flow tube 20, while in other
embodiments the change in thickness or material composition may be
applied to only part of the circumference of the flow tube in an
increased thickness region or location.
[0045] As discussed generally herein, varying the stiffness in the
direction of the oscillation axis along the flow axis (e.g., axis
91) of the flow tubes modifies the oscillations (e.g., modes) along
the oscillation axis (e.g., vertical axis 94). Additionally, there
are other factors for tuning the oscillation that result in an
increased Coriolis phase shift. FIG. 7 is a schematic illustration
of a vertical axis 122 and a lateral axis 124 along a flow tube 20.
As shown, the oscillation 126 occurs in a plane 125 spanning the
vertical axis 122 and the flow axis 91. Unwanted harmonic modes
(e.g., structural modes) may occur along the axes 122 and 124 and
contribute to the Coriolis deflection shape (e.g., Coriolis
deflection shape 58; FIG. 2). In order to damp or shift the
frequency of unwanted harmonic modes of tubing fluid flow assembly
18, additional structural features may be added to either a uniform
stiffness flow tube 17, as shown, or a variable stiffness flow tube
20 (e.g., modal features). Structural features along certain axes
(e.g., 122 and 124) may provide independent influence on the
different vibration modes with a variable cross section that
adjusts (e.g., shift the frequency of the harmonic mode up, shift
the frequency down, or decrease the amplitude) the unwanted
harmonic modes until the effect of the unwanted harmonic modes is
negligibly, resulting in increased sensitivity and robustness of
the Coriolis flow sensor assembly. The features that alter the
unwanted harmonic modes (e.g., modal features) may have various
designs, structures, and properties to address different modes.
[0046] For example, modal features may include vertical fin
structures 127 to increase stiffness in the vertical axis 122,
resulting in better control of the Coriolis deflection shape.
Additionally, modal features may include lateral fin structures 128
(e.g., pectoral fins) to adjust (e.g., prevent, shift, or decrease)
modes along the lateral axes 124. The lateral fin structures 128
increase the stiffness in the lateral plane while providing little
to no negative effects on the modes along the vertical axis 122. In
one embodiment, the vertical fin structure 127 may be formed
integrally with the structure of the flow tube 20 via an extension
or a variable thickness of the walls of the flow tube. In certain
embodiments, the vertical fin structure or other structures as
provided herein may be implemented as a structural support
component 24 that is coupled to the flow tube 20. In one
embodiment, the structural support component 24 is reversibly
coupled to the flow tube 17 or the flow tube 20 to permit
exchanging or replacing used flow tubes while retaining the
reusable components of the sensor assembly 14 (FIG. 1). It should
be appreciated by one of ordinary skill in the art that the
structural support component 24 addition to modify the stiffness of
the flow tube as discussed in FIG. 5. Moreover, one of ordinary
skill in the art would recognize that an attachable structural
support component may be suitable for a disposable (e.g.,
attachable and removable) or reusable flow tube. When coupled to
the flow tube (e.g., flow tube 17 or flow tube 20), the structural
support component 24 is configured to permit oscillation of the
coupled flow tube. In certain embodiments, the structural support
component oscillates together with the flow tube.
[0047] FIGS. 8 and 11-13 illustrate different embodiments of a
Coriolis flow sensor. In particular, FIGS. 8 and 11-13 show a flow
tube coupled to a structural support component 24 having different
features (e.g., fins) and an associated Coriolis phase shift
sensitivity measurement. In general, the embodiments discussed
below show increased Coriolis phase shift sensitivity, which is
exemplified by the range of measured Coriolis phase shifts based on
flow rates.
[0048] FIG. 8 shows a vertical fin structural support component 24
coupled to the flow tube in accordance with the present disclosure.
Image 128 shows the experimental setup used to determine the
Coriolis phase shift sensitivity based on variable flow rates. The
image 128 shows the flow tube, the oscillator 28, and the vertical
fin structural support component 24. The graph 130 shows the
Coriolis phase shift versus the flow rate of the flow tube in image
128. The points 132 from the measured Coriolis phase shift versus
flow rate generally fit a line.
[0049] FIG. 9 shows the lateral mode 136 and drive or operating
mode 138 of an implementation of the structural support component
24. The FEA simulation shows the lateral mode has a frequency of 97
Hz, which is close to the operating mode frequency of 150 Hz. It
should be appreciated by one of ordinary skill in the art that
while the Coriolis flow sensor assembly performed well (e.g., the
measured phase shifts for a given flow rate fit a linear equation)
additional modifications (e.g., modal features) may improve the
performance of the Coriolis flow sensor assembly for certain
conditions (e.g., flow rates). The illustrated structural support
component 24 may have a body 125 that includes extending fin
portion(s) 127 that are generally positioned at areas that
correspond with the flow tube ends (e.g., the fluid entry point 27
and exit point 29) and that extend away from the flow tube a
distance d.sub.1. The body is thinner in a center portion 135,
e.g., extending to a distance d.sub.2 that is less than d.sub.1. To
couple to the flow tube, the body 125 includes a plurality of ribs
137 that form a receiving area 139 and that are sized and shaped to
couple to the flow tube (e.g., flow tube 17 or flow tube 20), for
example by forming a partial annulus about the flow tube that
permits an operator to insert and/or remove the flow tube. A flow
tube, when coupled to the structural support component 24, would
experience decreased oscillation along a lateral plane extending
outwardly from the lateral mode arrows 136.
[0050] FIG. 10 shows a plot of the frequencies of the drive
oscillation, 140, the lateral mode 142, and the bending mode 144.
An illustration of the modes is shown in 141, 143, and 145 for each
mode 140, 142, and 144 respectively. The structural support
components adjust the harmonic mode (e.g., shift the frequency of
the mode up or down or decrease the amplitude until the unwanted
modes can be neglected). For example, a frequency margin of at
least 1.5 between the drive oscillation and the lateral mode was
found to significantly decrease the dynamic response of the lateral
mode. Additionally, a frequency margin of at least 2.0 between the
drive oscillation and the bending mode resulted in additional
improvements of the performance of the Coriolis flow sensor
assembly.
[0051] FIG. 11 shows the Coriolis phase shift sensitivity of a
Coriolis flow sensor assembly including the flow tube 20 coupled to
an implementation of the structural support component 24 having
vertical fins and lateral fins in accordance with the present
disclosure. Image 148 shows an experimental setup used to determine
Coriolis phase shift sensitivity based on variable flow rates that
includes the flow tube 20, the oscillator 30, and the structural
support component 146. As shown in the schematic 150, the flow tube
oscillates in a direction 152 that is perpendicular to the flow
path. The graph 154 shows the Coriolis phase shift versus the flow
rate of the flow tube depicted in image 146 having the structural
support component 24 illustrated in schematic 150. The measured
Coriolis phase shift versus flow rate for the flow tube 20 coupled
to the structural support component 24 fits linear equation (e.g.,
represented as line 156). The measured Coriolis phase shift of a
Coriolis flow sensor assembly including the structural support
component 24 having vertical fins and laterals fins is 19 .mu.s,
which is greater than the 4 .mu.s phase shift of a Coriolis flow
sensor assembly having constant stiffness.
[0052] FIG. 12 shows the Coriolis phase shift sensitivity for a
flow tube 20 coupled to an implementation of a dual fin structural
support component 24 in accordance with the present disclosure.
Image 160 shows an experimental setup used to determine the
Coriolis phase shift sensitivity based on variable flow rates
including the flow tube 20, the oscillator 30, and the dual fin
structural support component 24. The dual fin structural support
component 24 includes an interior space 158 between the fin
structures. As illustrated, the interior space 158 is hollow;
however, in other embodiments, the interior space 158 may be solid,
or partially solid (e.g., porous), and may be composed of a
material that is different than the rest of the dual fin structural
support component 24. A first schematic 162 shows an illustration
of the dual fin structural support component 24 with Coriolis
forces illustrated as arrows 164. A second schematic 166 shows a
side perspective view of the dual fin structural support component
24. The graph 168 shows the Coriolis phase shift versus the flow
rate of the flow tube depicted in schematics 162, 166, and image
160. The measured Coriolis phase shift of a Coriolis flow sensor
assembly including the dual fin structural support component 24 is
22 .mu.s, which is greater than the 4 .mu.s phase shift of a
Coriolis flow sensor assembly having constant stiffness.
[0053] FIG. 13 shows a structural support feature 24 in accordance
with the present disclosure. As discussed above, structural support
features may be added to the Coriolis flow tube to reduce the
effects of unwanted harmonic oscillations on the drive oscillation
that results from the mechanical drive assembly 32. In general,
structural support components may have features that address
unwanted harmonic oscillations in one axis (e.g., either vertical
or lateral). For example, although the structural support component
having vertical fins shown in FIG. 8 improved the Coriolis phase
shift sensitivity of the Coriolis flow sensor assembly, the
Coriolis flow sensor assembly showed a lower sensitivity under
certain conditions (e.g., at point 110). The structural support
component 116 with lateral and vertical fins, shown in FIG. 10,
results in increased Coriolis phase shift sensitivity; however, in
certain embodiments, it would be recognized by one of ordinary
skill in the art that additional features (e.g., modal features)
may add less desirable bulkiness of the flow tube. FIG. 13
illustrates a structural support component 24 with features that
address unwanted harmonic features along several axes. In general,
the structural support component 24 permits different regions of
the flow tube to have variable bending stiffness, lateral
stiffness, and vertical stiffness. When coupled to the flow tube,
the structural support component 24 may be in direct contact with
the flow tube along an entirety of the length of the flow tube or,
in certain embodiments, along some of a length of the flow
tube.
[0054] The structural support component 24 illustrated in FIG. 13
has a first region 172, a second region 174, and a third region 176
along a back bone structure 178 having rib structures 180 that
allow for the structural support component 24 to couple to the flow
tube 20. The backbone structure 178 has a first backbone 182 and a
second backbone 184 separated by a distance 186. The first region
172 and the second region 174 have similar structural features.
Moreover, the distance 186 between the first backbone 182 and the
second backbone 184 is similar. Image 188 illustrates a
representative cross sectional view along the length of the
structural support component 24 in the third region 176. Image 190
illustrates a representative cross sectional view along the length
of the structural support component 24 in the first region 172 and
the second region 174. As shown, the distance 186 between the first
backbone 182 and the second backbone 184 (e.g., a greater arc
length around the rib structure 180) in the first region 172 and
second region 174 is greater than the distance 186 between the
first backbone 182 and the second backbone 184 shown in image 190.
A greater distance 186 results in greater lateral stiffness. Thus,
the lateral stiffness along the flow tube 20 may be tuned based on
the distance between the backbones 182 and 184.
[0055] As further illustrated in FIG. 13, the first backbone 182
and second backbone 184 have a variable thickness. In the first
region 172 and the second region 174, the backbone has a greater
thickness 192 than in the third region. The greater backbone
thickness 192 results in a greater vertical stiffness of the flow
tube 20 when the structural support component 170 is coupled to the
flow tube 20. The thinner backbone thickness 192 of the third
region 176 imparts a lower vertical stiffness to the flow tube 20
when the structural support component is coupled to the flow tube
20. Thus, the structural support component 170 may impart a
variable vertical stiffness to the flow tube 20 in additional to a
variable lateral stiffness.
[0056] The disclosure relates to a Coriolis flow sensor with
features that reduce the contributions of unwanted harmonic modes
to the oscillation resulting from the mechanical drive assembly. As
discussed herein, the features may include a flow tube with
variable stiffness, which may be implemented through features of
the flow tube itself such as a variable wall thickness of the flow
tube or through varying the material composition of the flow tube.
Additionally, variable stiffness may be achieved by including
structural support features integrally with or via an external
structural support component coupled to the flow tube. The
structural support component may include subcomponents (e.g., fins
and backbones) that affect the stiffness of the flow tube along
different axes that damp or shift the frequency of unwanted
oscillations from the frequency of the oscillation imparted by the
oscillator.
[0057] This written description uses examples to enable any person
skilled in the art to practice the embodiments of the disclosure,
including making and using any devices or systems and performing
any incorporated methods. The patentable scope is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *