U.S. patent application number 11/524639 was filed with the patent office on 2007-02-15 for method of manufacturing a flowmeter for the precision measurement of an ultra-pure material flow.
Invention is credited to Mark James Bell, Leland Charles Leber, Daniel Patrick McNulty, Martin Andrew Schlosser, Matthew Glen Wheeler.
Application Number | 20070033793 11/524639 |
Document ID | / |
Family ID | 25540473 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070033793 |
Kind Code |
A1 |
Schlosser; Martin Andrew ;
et al. |
February 15, 2007 |
Method of manufacturing a flowmeter for the precision measurement
of an ultra-pure material flow
Abstract
A method of manufacturing a Coriolis flowmeter for the
measurement of a process material requiring an ultra high level of
purity. This is achieved by forming the entire flow path of the
Coriolis flow meter from a PFA plastic material that does not
transfer ions from the Coriolis flowmeter to the process material
flowing through the flowmeter.
Inventors: |
Schlosser; Martin Andrew;
(Lafayette, CO) ; Bell; Mark James; (Longmont,
CO) ; Wheeler; Matthew Glen; (White Salmon, WA)
; McNulty; Daniel Patrick; (Westminster, CO) ;
Leber; Leland Charles; (Fort Collins, CO) |
Correspondence
Address: |
THE OLLILA LAW GROUP LLC
2060 BROADWAY
SUITE 300
BOULDER
CO
80302
US
|
Family ID: |
25540473 |
Appl. No.: |
11/524639 |
Filed: |
September 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09994257 |
Nov 26, 2001 |
7127815 |
|
|
11524639 |
Sep 21, 2006 |
|
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|
Current U.S.
Class: |
29/428 |
Current CPC
Class: |
G01F 1/8495 20130101;
G01F 1/8477 20130101; Y10T 29/49826 20150115; G01F 1/8413 20130101;
G01F 15/006 20130101; G01F 1/8409 20130101; G01F 1/849 20130101;
Y10T 29/494 20150115; G01F 1/8427 20130101; G01F 1/8404
20130101 |
Class at
Publication: |
029/428 |
International
Class: |
B21D 39/03 20060101
B21D039/03 |
Claims
1. A method of manufacturing a Coriolis flowmeter; said method
comprising the steps of: coupling a flow tube to a base, wherein
said flow tube is formed entirely from a material that does not
release deleterious ions into a substance flowing through the
flowmeter and where said flow tube is configured to vibrate along a
length of said flow tube where the length of said flow tube is
defined from where the flow tube is coupled to said base at a first
location to where the flow tube is coupled to said base at a second
location; affixing a driver to said length of said flow tube;
coupling a pick-off sensor to said length of said flow tube.
2. The method of manufacturing a Coriolis flowmeter of claim 1
where the material is selected from the group: perfluoroalkoxy
copolymer (PFA) or polytetrafluorethylene (PTFE).
Description
RELATED APPLICATIONS
[0001] This application is a continuation of prior application Ser.
No. 09/994,257 filed Nov. 26, 2001, which is hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to a method of manufacturing a
Coriolis flowmeter that measures a flow of process material having
an ultra high level of purity.
PROBLEM
[0003] It is known to use Coriolis effect mass flowmeters to
measure mass flow and other information pertaining to materials
flowing through a pipeline as disclosed in U.S. Pat. No. 4,491,025
issued to J. E. Smith, et al. of Jan. 1, 1985 and U.S. Pat. No. Re.
31,450 to J. E. Smith of Feb. 11, 1982. Flowmeters have one or more
flow tubes of a straight, curved or irregular configuration. Each
flow tube has a set of natural vibration modes which may be of a
simple bending, torsional, or twisting type. Each material filled
flow tube is driven to oscillate at resonance in one of these
natural modes. The natural vibration modes are defined in part by
the combined mass of the flow tubes and the material within the
flow tubes. If desired, a flowmeter need not be driven at a natural
mode.
[0004] Material flows into the flowmeter from a connected material
source on the inlet side. The material passes through the flow tube
or flow tubes and exits the outlet side of the flowmeter.
[0005] A driver applies force to oscillate the flow tube. When
there is no material flow, all points along a flow tube oscillate
with an identical phase in the first bending mode of the flow tube.
Coriolis accelerations cause each point on the flow tube to have a
different phase with respect to other points on the flow tube. The
phase on the inlet side of the flow tube lags the driver; the phase
on the outlet side leads the driver. Pickoffs are placed on the
flow tube to produce sinusoidal signals representative of the
motion of the flow tube. The phase difference between two sensor
signals is divided by the frequency of oscillation to obtain a
delay which is proportional to the mass flow rate of the material
flow.
[0006] It is known to use flowmeters having different flow tube
configurations. Among these configurations are single tube, dual
tube, straight tube, curved tube, and flow tubes of irregular
configuration. Most of the flowmeters are made of metal such as
aluminum, steel, stainless steel and titanium. Glass flow tubes are
also known. In addition, all straight serial path flowmeters
currently in the art are made out of metal, particularly Titanium,
or are metal tubes lined with plastic, particularly PTFE or
PFA.
[0007] The positive attributes of Titanium in these types of
flowmeters are its high strength and low coefficient of thermal
expansion (CTE). The negative attributes of Titanium are its
metallic properties and cost of manufacturing. For example, in
semiconductor wafer processing, metal ions are a contaminant. Metal
ions in contact with the wafer areas of an integrated circuit can
cause a short circuit and ruin the device. Also, a Titanium
flowmeter is difficult and expensive to produce.
[0008] Flow tubes lined with PFA, as disclosed in U.S. Pat. No.
5,403,533 to Dieter Meier, attempted to combine the positive
attributes of both technologies but encountered new challenges that
could not be solved until the present invention. Metal flow tubes
lined with PFA still allowed metal ions to migrate through the thin
coating layer of PFA and into the flow stream, causing
contamination. Also, the flow tube material and the PFA liner had
different thermal properties. This caused the PFA liner to
disengage from the flow tube creating leaks and performance
problems. The manufacturing process for lining the metal flow tubes
with PFA is also extremely costly. The prior art also suggests
plastic flow tubes and plastic flowmeters. This includes prior art
in which the entirety of the flowmeter is plastic as well as that
in which only the flow tube is formed of plastic. Much of this
prior art is directed to metal flowmeters and merely contains an
assertion that a flowmeter may be made of various materials such as
steel, stainless steel, titanium or plastic. This prior art is not
instructive in so far as concerns the disclosure of a plastic
Coriolis flowmeter that can accurately output information over a
range in operating conditions including temperature.
[0009] The mere substitution of a plastic flow tube for a metal
flow tube will produce a structure that looks like a flowmeter.
However, the structure will not function as a flowmeter to generate
accurate output information over a useful range of operating
conditions. The mere assertion that a flowmeter could be made out
of plastic is nothing more than the abstraction that plastic can be
substituted for metal. It does not teach how a plastic flowmeter
can be manufactured to generate accurate information over a useful
range of operating conditions.
[0010] It is a problem in some applications that the typical
Coriolis flow meter may contaminate the process material. This is
undesirable for systems in which material of an ultra high level of
purity must be delivered by the flowmeter to a user application.
This is the case in the fabrication of semi-conductor wafers which
requires the use of a process material that is free of contaminants
including ions migrating from the tubes of the process material
flow path. In such applications, the flow tube can be a source of
contaminants. The metal walls of a flow tube can release ions into
the process material flow. The released ions can cause the chips on
a semi-conductor wafer to be defective. The same is true for a
glass flow tube which can release the lead ions from the glass into
the process material flow. The same is also true for the flow tubes
formed of conventional plastics.
[0011] A plastic termed PFA is free from this objection since the
material of which it is composed does not release deleterious ions
into the material flow. The use of PFA for a flow tube is suggested
in U.S. Pat. No. 5,918,285 to Vanderpol. This suggestion is
incidental to the Vanderpol disclosure since the patent discloses
no information regarding how a flowmeter having a PFA flow tube
could be manufactured to generate accurate flow information.
SOLUTION
[0012] The above and other problems are solved and an advance of
the art is achieved by the present invention which discloses a
Coriolis flowmeter having at least one flow tube formed of
perfluoroalkoxy copolymer (PFA) plastic which is coupled to a
driver and to at least one pick-off sensor to enable the PFA flow
tube to function as part of Coriolis flowmeter that can provide
accurate output information over range of operating conditions for
a material flow and ultra high purity suitable for use in
applications such as semi-conductor fabrication and the like which
require the material flow to be free of contaminants and to the
ionic level.
[0013] A flow path constructed entirely of PFA has many of the
benefits of Titanium and PFA lined flow tubes without the
drawbacks. PFA is a fluoropolymer with superior chemical
resistance, little metal ion release, low particle generation, and
is manufacturable without expending large amounts of capital. PFA
material is strong and can be extruded into high quality thin wall
tubing. Thin-walled PFA tubing has low flexural stiffness enabling
a higher sensitivity to mass flow rate and improved immunity to
elastic dynamic interaction between the flow tube and the process
pipeline. The material and physical properties of PFA allow larger
tube vibration amplitudes at higher stress levels and resulting
near infinite fatigue life span. Also, the higher vibration
amplitude allows the use of small low-mass transducers, which in
turn improves density sensitivity and immunity to mount
variation.
[0014] A first preferred exemplary embodiment of the invention
comprises a flowmeter having a single PFA plastic flow tube
vibrationally connected to a massive metal base which vibrationally
balances the end nodes of the flow tube. In this embodiment, the
base is U-shaped and the plastic flow tube extends through holes in
the outer portion of the leg of the U. The plastic flow tube is
affixed to the base structure by means of an O-ring or an
appropriate adhesive, particularly cyanoacrylate, which surrounds
the flow tube and rigidly adheres the flow tube to the metal base.
The center of the flow tube is affixed to an electro-magnetic
driver which receives a drive signal from suitable meter
electronics to vibrate the flow tube transversely to the
longitudinal access of the flow tube. The flow tube is also coupled
to pick-off sensors which detect the Coriolis response of the
material flow within the vibrating flow tube. Connected to the base
and terminating the flow tube are process connections, also made
out of PFA.
[0015] PFA is a fluorinated polymer that is chemically inert and
has a very low surface energy, making it difficult to bond to using
common adhesives or solvents. In order to facilitate the bonding
between the PFA components of the flowmeter and non-PFA components.
A preferred method of manufacturing includes a process whereby the
PFA components are etched. Etching changes the exterior surface
chemistry of the PFA components allowing them to be bonded to
non-PFA components. The etching process entails submersing the PFA
components into a heated bath containing a glycol diether,
preferably diglyme-sodium naphthalene, and gently agitate the PFA
components for a period of time.
[0016] Another characteristic of PFA, specific to tubing, is that
its method of manufacture results in tubing that has inherent bends
or curvature that need to be eliminated from the tubing prior to
manufacturing it into a flowmeter. A preferred method of
eliminating unwanted curvatures in the tubing prior to processing
is to straighten the flow tube through an annealing process. The
annealing process comprises placing the flow tube in a
straightening fixture. The fixture restrains the tube in a straight
form suitable for processing into a flowmeter. The flow tube and
fixture are the heated for a period of time and then removed and
allowed to cool to room temperature. Upon reaching room temperature
the flow tubes are removed from the fixture resulting in a straight
flow tube.
[0017] As described in the first preferred embodiment, the flow
tube has coupled to it pick-off means. In one embodiment the
pick-off means are of the coil/magnet form. The magnet is attached
to the flow tube using an adhesive and the coil is attached to the
base using either an adhesive or mechanical connection. In an
alternative embodiment, the pick-offs are optical devices which
send and receive a light beam and which is modified by the motion
of the flow tube. In order to facilitate the use of optical
pick-offs potions of the flow tube are made opaque. This allows the
light to be reflected off the flow tube or absorbed by the opaque
coating instead of being passed through the normally translucent
flow tube. The flow tube can be made opaque through various means
including using coatings or paints. The optical sensing embodiment
offers the advantage of lighter weight on the vibrating flow
tube.
[0018] As described in the first preferred embodiment the flow tube
is coupled to a process connection to form a flow path of PFA. In a
further embodiment this connection is achieved by flaring the flow
tube so as to allow it to be inserted over the nipple of the
process connection. In another embodiment the flow tube is inserted
into the thru-hole of the process connection and sealed at the face
of the process connection.
[0019] In a preferred embodiment the tube is sealed to the face of
the process connection by the process of laser welding. Laser
welding is a non-contact form of welding that generates heat at the
interface between the flow tube and the face of the process
connection. Other methods of sealing the flow tube to the face of
the process connection are heated tip welding, ultrasonic welding,
and adhesives.
[0020] In addition to the tube being coupled to the process
connection the process connection is also coupled to the base. The
preferred method of coupling the process connection to the base is
to form a hole in the base and secure the end of the process
connection into the hole. The process connection can be secured by
tapping the base hole and threading the process connection end into
the tapped hole. An alternative to the above method is to simply
bond the process connection end into the base hole using an
adhesive. An additional method of securing the process connection
to the base is to form a locking hole in the base. The hole is
formed such that the centerline of the locking hole intersects with
the centerline of the receiving hole. After the holes are formed
and the process connection end is inserted into the receiving hole,
a locking mechanism is inserted in to locking hole to secure the
process connection. A preferred embodiment for locking the process
connection into the receiving hole is to tap the locking hole and
thread into the locking hole a set screw that what compress the
process connection and prevent movement.
[0021] Other flow tube configurations are provided in accordance
with other embodiment of the inventions. The invention may be
practiced with the use of dual flow tubes vibrating in phase
opposition. These dual tubes may either be of the straight type,
they may be u-shaped, or they may be of an irregular configuration.
The use of dual flow tubes is advantageous in that it provides a
dynamically balanced structure and reduces the mass of the base
required to mount the flow tubes.
[0022] In accordance with yet another embodiment, when dual
straight flow tubes are used, they may be mounted on the base and
vibrated in phase opposition in either a horizontal plane or a
vertical plane. Vibration in a horizontal plane perpendicular to
the bottom surface of the U-shaped base eliminates vertical shaking
of the flowmeter structure but permits horizontal shaking if the
dual flow tubes are not dynamically balanced. The mounting of the
flow tubes in a vertical plane with respect to each other limit any
undesired vertical vibrations.
[0023] An additional embodiment that can be associated with any
tube configuration is the implementation of a temperature
measurement device. A preferred embodiment is the use of a
Resistive Temperature Device (RTD) attached to a flow tube. In
accordance with another embodiment the temperature can be measured
using an infrared temperature measurement device. The benefits to
this device is that it is non-contact and can be located off the
tube, thereby reducing mass on the tube.
[0024] In summary, the flowmeter embodying the present invention is
advantageous in that it provides for the measurement and delivery
of an ultra pure process material in applications that require the
delivered material to be free of contamination. This level of
purity is provided by the use of a PFA plastic flow tube which is
chemically inert and which is superior to metals and glass permit
ion transfer from the flow tube material to the processed material.
The processed material may typically comprise a slurry which is an
organic compound used as a polishing agent in the fabrication of
wafers in the semi-conductor industry. This polishing operation
serves to provide a flat surface for the wafers. The polishing
operation can take from 60 to 90 seconds and during this time the
slurry must be free from any contaminants including ions
transferred from the flow tube material to the slurry. The deposit
of even a single undesired ion onto a semi-conductor wafer can
short circuit all or a portion of the wafer and render it
useless.
[0025] It can be seen that an aspect of the invention is a method
of manufacturing a Coriolis flowmeter adopted to extend a received
process material flow having an ultra high level of purity free
from contamination due to ion transfer from said Coriolis flow
meter to said process material; said method comprising the steps
of:
[0026] coupling a flow tube means to a base;
[0027] affixing a driver to said flow tube means;
[0028] coupling a pick-off means to said flow tube means; and
[0029] affixing inlet and outlet ends of said flow tube means to at
least one process connection to form an ultra pure flow path for a
process material flow through said flow tube means.
[0030] Preferably said step of coupling a flow tube means to said
base further comprises the step of using said flow tube means
formed from PFA to maintain said process material flow free from
contamination due to ion transfer from material of a flow tube to
process material.
[0031] Preferably said step of coupling said flow tube to said base
is proceeded by the step of etching said flow tube to create a
surface suitable for coupling and affixing flowmeter
components.
[0032] Preferably said etching step comprises the step of using an
etching solution containing a glycol diether.
[0033] Preferably said etching step comprises the step of heating
said etching solution to an elevated temperature.
[0034] Preferably said etching step comprises the step of agitating
said flow tube means in said etching solution.
[0035] Preferably said step of coupling said flow tube to a base is
proceeded by the step of straightening said flow tube means to
eliminate any inherent curvature or unwanted residual bends.
[0036] Preferably said straightening step comprises the steps
of:
[0037] placing said flow tube means in a straightening fixture;
[0038] heating said flow tube means and said straightening
fixture;
[0039] cooling said flow tube means and said straightening
fixture;
[0040] removing said flow tube means from said straightening
fixture.
[0041] Preferably said step of joining said flow tube means to said
base comprises the step of attaching said flow tube means to said
base using adhesive.
[0042] Preferably said step of attaching said flow tube means to
said base using said adhesive comprises the step of using
cyanoacrylate adhesive.
[0043] Preferably said step of joining said flow tube means to said
base comprises the step of coupling said flow tube to said base
using an O-ring.
[0044] Preferably said step of affixing said driver means to said
flow tube means further comprises the step of attaching said driver
means to said flow tube means using adhesive.
[0045] Preferably said step of affixing said driver means to said
flow tube means further comprises the step of using cyanoacrylate
adhesive.
[0046] Preferably said step of affixing said pick-off means to said
flow tube means further comprises the step of attaching said
pick-off means to said flow tube using adhesive.
[0047] Preferably said step of affixing said pick-off means to said
flow tube means further comprises the step of using cyanoacrylate
adhesive.
[0048] Preferably said method of manufacturing a Coriolis flow
meter further comprises coupling said at least one process
connection to said base.
[0049] Preferably said step of joining said process connection to
said base comprises the steps of:
[0050] forming a receiving hole into said base;
[0051] securing a fixed portion of said process connection into
said receiving hole.
[0052] Preferably said step of securing said fixed portion of said
process connection into said receiving hole comprises the step of
adhering said fixed portion of said process connection into said
receiving hole.
[0053] Preferably said step of securing said fixed portion of said
process connection into said receiving hole further comprises the
step of using cyanoacrylate adhesive.
[0054] Preferably said step of securing said fixed portion of said
process connection into said receiving hole comprises the step of
threading a fixed portion of said process connection into said
receiving hole Preferably said step of securing said fixed portion
of said process connection into said receiving hole comprises the
steps of:
[0055] forming a locking hole whose centerline intersect the
centerline of the receiving hole; and
[0056] inserting a locking mechanism into said locking hole to
prevent said
[0057] fixed portion of said process connection from moving.
[0058] Preferably said step of inserting a locking mechanism into
said locking hole comprises inserting a set screw that compresses
said fixed portion of said process connection.
[0059] Preferably said step of coupling said process connection to
said base comprises the step of adhering a fixed portion of said of
said process connection onto said base.
[0060] Preferably said step of adhering a fixed portion of said of
said process connection onto said base further comprises the step
of using cyanoacrylate adhesive.
[0061] Preferably said step of affixing said end of said flow tube
means to said at least one process connection comprises the steps
of:
[0062] flaring said end of said flow tube means; and
[0063] inserting said flared end of said flow tube means onto
conical stub of said at least one process connection.
[0064] Preferably said step of affixing said end of said flow tube
means to said at least one process connection comprises the steps
of:
[0065] inserting said end of said flow tube means through said at
least one process connection until said end of said flow tube means
are flush with face of said at least one process connection;
and
[0066] sealing said end of said flow tube means to said face of
said at least one process connection.
[0067] Preferably said step of sealing said end of said flow tube
means to said face of said at least one process connection
comprises the step of adhering said end of said flow tube means to
said face of said at least one process connection.
[0068] Preferably said step of sealing said end of said flow tube
means to said face of said at least one process connection
comprises the step of ultrasonically welding said end of said flow
tube means to said face of said at least one process
connection.
[0069] Preferably said step of sealing said end of flow tube means
to said face of said at least one process connection comprises the
step of heat tip welding said end of said flow tube means to said
face of said at least one process connection.
[0070] Preferably said step of sealing said end of flow tube means
to said face of said at least one process connection comprises the
step of laser welding said end of said flow tube means to said face
of said at least one process connection.
[0071] Preferably said step of coupling said pick-off means
comprises the step of making portions of said flow tube means
opaque in order to facilitate use of optical pick-offs.
[0072] Preferably said Coriolis meter is characterized by affixing
a temperature sensing device to said Coriolis flowmeter.
[0073] Preferably said step of affixing a temperature sensing
device comprises the step of affixing a resistance temperature
measuring device to said Coriolis flowmeter. Preferably said step
of affixing a temperature sensing device comprises the step of
affixing an infrared temperature measuring device to said Coriolis
flowmeter.
[0074] An additional aspect of the invention includes, a Coriolis
flowmeter for measuring a process material flow having an ultra
high level of purity; said Coriolis flowmeter comprising:
[0075] a base;
[0076] flow tube means coupled to said base;
[0077] a driver affixed to said flow tube means for vibrating said
flow tube means at the resonant frequency of said flow tube means
with process material flow;
[0078] pick-off means coupled to said flow tube means for
generating signals representing induced Coriolis deflections of the
portions of said vibrating material filled flow tube means
proximate said pick-off means; and
[0079] at least one process connection means coupled to said flow
tube means to form an ultra pure flow path for a process material
to flow through.
[0080] Preferably said Coriolis flowmeter is formed of PFA to
maintain said process material flow free from contamination due to
ion transfer from said flow tube means to said process
material.
[0081] Preferably said Coriolis flow meter comprises an O-ring for
coupling said flow tube means to said base.
[0082] Preferably said Coriolis flow meter is characterized in that
said process connection means is coupled to said base.
[0083] Preferably said base comprises at least one receiving hole
for securing a fixed portion of said process connection means.
[0084] Preferably said receiving hole for securing a fixed portion
of said process connection means is threaded.
[0085] Preferably said base comprises at least one locking hole for
securing said process connection means into said receiving
hole.
[0086] Preferably said locking hole for securing said process
connection means into said receiving hole is threaded.
[0087] Preferably said locking hole for securing said process
connection means into said receiving hole comprises a locking
mechanism.
[0088] Preferably said locking mechanism for securing said process
connection means into said receiving hole is a set screw.
[0089] Preferably said process connection means is of the flare
connection type.
[0090] Preferably said flow tube means comprises portions that are
opaque preventing light from passing through said flow tube
means.
[0091] Preferably said Coriolis flowmeter further comprises a
temperature sensing device.
[0092] Preferably said temperature sensing device is of the
resistive type.
[0093] Preferably said temperature sensing device is of the
infrared type.
DESCRIPTION OF THE DRAWINGS
[0094] These and other advantages and features of the present
invention may be better understood in connection with a reading of
the following detailed description thereof in connection of the
drawings in which:
[0095] FIG. 1 discloses a perspective view of a first exemplary
embodiment of the invention.
[0096] FIG. 2 is a top view of the embodiment of FIG. 1.
[0097] FIG. 3 is a front view of the embodiment of FIG. 1.
[0098] FIG. 4 is a cross-sectional view taken along lines 4-4 of
FIG. 2.
[0099] FIG. 5 is a perspective view of an alternative embodiment
having a pair of base elements.
[0100] FIG. 6 discloses a dynamically balanced flowmeter having a
U-shaped base.
[0101] FIGS. 7 and 8 disclose a flowmeter having optical
pick-offs.
[0102] FIGS. 9 and 10 disclose flowmeters having dynamic
balancers.
[0103] FIG. 11 discloses a flowmeter having a pair of substantially
U-shaped flow tubes.
[0104] FIGS. 12 and 13 discloses another embodiment of a flowmeter
having a pair of dynamically balanced straight flow tubes.
[0105] FIG. 14 discloses an alternative embodiment having a single
flow tube and no return tube.
[0106] FIG. 15 discloses an alternative embodiment having two flow
tubes vibrated in phase opposition.
[0107] FIG. 16 discloses an alternative embodiment having a single
flow tube.
DETAILED DESCRIPTION
Description of FIG. 1
[0108] FIG. 1 is a perspective view of a first possible exemplary
embodiment of the invention and discloses a flowmeter 100 having a
flow tube 102 inserted through legs 117, 118 of base 101. Pick-offs
LP0 and RP0 and driver D are coupled to flow tube 102. Flowmeter
100 receives a process material flow from supply tube 104 and
extends the flow through process connection 108 to flow tube 102.
Flow tube 102 is vibrated at its resonant frequency with material
flow by driver D. The resulting Coriolis deflections are detected
by pick-offs LP0 and RP0 which apply signals over conductors 112
and 114 to meter electronics 121. Meter electronics 121 receives
the pick-off signals, determines the phase difference between,
determines the frequency of oscillation and applies output
information pertaining to the material flow over output path 122 to
a utilization circuit not shown.
[0109] The material flow passes from flow tube 102 and through tube
106 which redirects the material flow through return tube 103
through process connection 107 to exit tube 105 which delivers the
material flow to a user application. This user application may be a
semiconductor processing facility. The process material may be a
semiconductor slurry which is applied to the surface of a
semiconductor wafer to form a flat surface. The PFA material used
in the flow tubes shown on FIG. 1 ensures that the process material
is free of impurities such as ions which could be transferred from
the walls of metals or glass flow tubes.
[0110] In use, flow tube 102 is of a narrow diameter approximating
that of a soda straw and of negligible weight such as, for example,
0.8 gram plus 0.5 gram for the process material. This excludes the
weight of the magnets. The magnets associated with the pick-offs
and driver have a mass of about 0.6 grams total so that the
combined mass of the flow tube 102, the affixed magnets and the
process material is approximately 2 grams. Vibrating flow tube 102
is a dynamically unbalanced structure. Base 102 is massive and
weighs approximately 12 pounds. This provides a ratio of the mass
of the base to that of a material filled flow tube of approximately
3,000 to 1. A base of this mass is sufficient to absorb vibrations
generated by the dynamically unbalanced flow tube 102 with material
flow.
[0111] Process connections 107, 108, 109 and 110 connect tubes 104,
105 and 106 to the ends of flow tube 102 and return tube 103. These
process connections are shown in detail in FIG. 4. The process
connections have a fixed portion 111 that includes threads 124.
Locking holes 130 receive set screws 411 to fixably connect element
111 to base 101 as shown in FIG. 4. The movable portion of process
connections 107 through 110 are threaded onto male threads 124 to
connect their respective tubes to the fixed body of the process
connection of which the hexagonal nut portion 111 is a part. These
process connections function in a manner similar to the well known
copper tubing flared process connections to connect tubes 104, 105
and 106 to ends of flow tube 102 and return tube 103. Details
regarding the process connections are further shown in FIG. 4. RTD
is a temperature sensor that detects the temperature of return tube
103 and transmits signals representing the detected temperature
over path 125 to meter electronics.
Description of FIG. 2
[0112] In FIG. 2 is a top view of flowmeter 100 of FIG. 1.
Pick-offs LP0 and RP0 and driver D each include a coil C. Each of
these elements further includes a magnet which is affixed to the
bottom portion of flow tube 102 as shown in FIG. 3. Each of these
elements further includes a base, such as 143 for driver D, as well
as a thin strip of material, such as 133 for driver D. The thin
strip of material may comprise a printed wiring board to which coil
C and its winding terminals are affixed. Pickoffs LP0 and RP0 also
have a corresponding base element and a thin strip fixed to the top
of the base element. This arrangement facilitates the mounting of a
driver or a pickoff to be accomplished by the steps of gluing a
magnet M to the underside of PFA flow tube, gluing the coil C to a
printed wiring board 133 (for driver D), positioning the opening in
coil C around the magnet M, moving the coil C upwardly so that the
magnet M fully enters the opening in coil C, then positioning base
element 143 underneath the printed wiring board 133 and gluing
these elements together so that the bottom of base 143 is affixed
by glue to the surface of the massive base 116.
[0113] The male threads 124 of process connections 107-110 are
shown on FIG. 2. The inner details of each of these elements is
shown on FIG. 4. Opening 132 receives conductors 112, 113 and 114.
Meter electronics 121 of FIG. 1 is not shown on FIG. 2 to minimize
drawing complexity. However it is to be understood that the
conductors 112, 113 and 114 extend through opening 132 and further
extend over path 123 of FIG. 1 to meter electronics 121 of FIG.
1.
Description of FIG. 3
[0114] FIG. 3 shows pick-offs LP0, RP0 and driver D as comprising a
magnet M affixed to the bottom portion of flow tube 102 and a coil
C affixed to the base of each of elements LP0, RP0 and driver
D.
Description of FIG. 4
[0115] FIG. 4 is a sectional taken along line 4-4 of FIG. 2. FIG. 4
discloses all the elements of FIG. 3 and further details of process
connections 108 and 109 and O-rings 430. O-rings 430 couple flow
tube 102 to base 401. FIG. 4 further discloses openings 402, 403
and 404 in base 101. The top of each of these openings extends to
the lower surface of the base of pick-offs LP0, RP0 and driver D.
The coil C and magnet M associated with each of these elements is
also shown on FIG. 4. Meter electronics 121 of FIG. 1 is not shown
on FIGS. 3 and 4 to minimize drawing complexity. Element 405 in
process connection 108 is the inlet of flow tube 102; element 406
in process connection 109 is the outlet of flow tube 102.
[0116] The fixed portion 111 of process connection 108 includes
male threads 409 which screw into mating threads in receiving hole
420 located in base 401 to attach fixed portion 111 to segment 401
of base 101. The fixed portion of process connection 109 on the
right is similarly equipped and attached by threads 409 into
receiving hole 420 located in element 401 of base 101.
[0117] Fixed element 111 of process connection 108 further includes
a threaded portion 124 whose threads receive the movable portion
415 of process connection 108. Process connection 109 is similarly
equipped. Fixed element 111 of process connection 108 further
includes on its left a conical stub 413 which together with movable
element 415 acts as a flare fitting to force the right end of input
tube 104 over the conical stub 413 of fixed portion 111. This
creates a compression fitting that sealably affixes the flared
opening of supply tube 104 onto the conical stub portion 413 of
fixed portion 111 of the process connection. The inlet of flow tube
102 is positioned in process connection fixed portion 111 and is
flush with face 425 of stub 413. By this means, the process
material delivered by supply tube 104 is received by inlet 405 of
flow tube 102. The process material flows to the right through flow
tube 102 to fixed portion 111 of process connection 109 where the
outlet 406 of flow tube 102 is flush with face 425 of stub 413.
This sealably affixes the outlet of flow tube 102 to connector 109.
The other process connections 107 and 110 of FIG. 1 are identical
to those described for the details of process connections 108 and
109 on FIG. 4.
Description of FIG. 5
[0118] FIG. 5 discloses flowmeter 500 as an alternative embodiment
of the invention similar to that of FIG. 1 except that the base of
the flowmeter 500 is not a single element and comprises separate
structures 517 and 518. Flow tube 502 and return tube 503 extend
through the elements 517, 518 to process connections 507 through
510 which are comparable in every respect to process connections
107 through 110 of FIG. 1. Flowmeter base elements 517, 518 are
separate and each is of sufficient mass to minimize the vibrations
imparted by driver D to the dynamically unbalanced structure
comprising flow tube 502. Base elements 517 and 518 rest on surface
515 of element 516 which supports base elements 517 and 518.
[0119] All elements shown on FIG. 5 operate in the same manner as
do their corresponding elements on FIG. 1. This correspondence is
shown by the designation of each element which differs only in that
the first digit of the part designation of the element. Thus,
supply tube 104 on FIG. 1 corresponds to supply tube 504 on FIG.
5.
Description of FIG. 6
[0120] FIG. 6 discloses yet another alternative embodiment of the
invention as comprising flowmeter 600 which is different from the
embodiment of FIG. 1 in that flowmeter 600 has two active flow
tubes 602 and 603 which comprise a dynamically balanced structure
that does not require the massive base such as base 101 of FIG. 1.
Base 601 may have significantly less mass than that of FIG. 1.
Flowmeter 600 has process connections 607 through 610 comparable to
process connections 107-110 of FIG. 1. In addition, it has process
connections 611, 612. Process material is received by flowmeter
600
[0121] from a supply tube 604. The material extends via a process
connection 608 to the left end of flow tube 602. Flow tube 602
extends through leg 618 of base 601 and process connection 609 by
means where it is connected to tube 615 which loops back via
process connection 607 to flow tube 603. Flow tube 603 is vibrated
in phase opposition to flow tube 602 by driver D. The Coriolis
response of the vibrating flow tubes 602 and 603 is detected by
pick-offs LP0 and RP0 and transmitted via conductors not shown to
meter electronics element also not shown to minimize drawing
complexity.
[0122] The material flow through tube 603 proceeds to the right and
extends via process connection 610 to tube 606 which loops back
through process connection 611 and tube 616, process connection 612
to return flow tube 605 which delivers the material flow to the
application process of the end user.
[0123] Flow tube 600 is advantageous in that it comprises a
dynamically balanced structure of flow tubes 602 and 603 formed of
PFA material. The dynamically balanced structure is advantageous in
that the massive base 101 of FIG. 1 is not required. Base 601 may
be of conventional mass and vibrating PFA tubes 602 and 603 to
provide output information pertaining to the material flow. The PFA
flow tubes ensure that the material flow have an ultra high level
of purity.
Description of FIGS. 7 and 8
[0124] FIG. 7 discloses a top view of a flowmeter 700 comparable to
flowmeter 100 of FIG. 1. The difference between the two embodiments
is that flowmeter 700 uses an optical detector for pick-offs LP0
and RP0. The details of the optical detectors are shown in FIG. 8
as comprising a LED light
[0125] source and photo-diode together with a flow tube 702, with
portions 720 made opaque in order to facilitate use, interposed
between the LED and photo-diode. At the rest position of the flow
tube, a nominal amount of light passes from the LED to the
photo-diode to generate a nominal output signal. A downward
movement of the flow tube increases the amount of light received by
the photo-diode; an upward movement of the flow tube decreases the
amount of light received by the photo-diode. The amount of light
received by the photo-diode translates to an output current
indicative of the magnitude of the Coriolis vibration for the
portion of the flow tube 702 associated with the LED and the light
source. The output of the photo-diodes are extended over conductors
730 and 732 to meter electronics not shown in FIG. 7 to minimize
drawing complexity. The embodiment of FIG. 7 is otherwise identical
in every respect to the embodiment of FIG. 1 and includes supply
tubes 704, exit tube 705 together with process connections 707
through 710 flow tubes 702 and exit tube 703. The parts of
flowmeter 700 and their counterparts on FIG. 1 and are designated
to facilitate the correspondence with the only difference being the
first digit of the designation of each element.
Description of FIG. 9
[0126] FIG. 9 discloses flowmeter 900 which corresponds to
flowmeter 100 of FIG. 1 except that flowmeter 900 is equipped with
dynamic balancers 932 and 933. Base 901 is smaller and of less mass
than 101 of FIG. 1. The dynamic balancers function to counteract
the vibrations imparted to legs 917 and 918 of base 901 by the
dynamically unbalanced structure comprising the material filled
vibrating flow tube 902. In the embodiment of FIG. 1, these
vibrations
[0127] are absorbed by the massive base 101. In this embodiment,
the material filled flow tube with the attached magnets weigh
approximately 2 grams while the base weighs approximately 12
pounds. This limits the range of commercial applications for the
flow tube of FIG. 1 since the upper limit on the size and mass of
the material filled vibrating flow tube 102 is limited by the mass
of the base that must be provided to absorb unbalanced vibrations.
Using the 3,000 to 1 ratio between the mass of the base and the
mass of the material filled vibrating flow tube, an increase of one
pound in the mass of the material filled flow tube would require an
increase of mass of 3,000 pounds for base 101. This clearly limits
the range of commercial applications in which the flow tube 100 of
FIG. 1.
[0128] Flowmeter 900 of FIG. 9 has a wider range of commercial
applications since the dynamic balancers 932 and 933 are affixed to
legs 917 and 918 to absorb much of the vibrations imparted to the
legs by the dynamically unbalanced vibrating flow tube 902. In
practice, dynamic balancers (DB) may be of any type including the
conventional mass and spring configuration as is well known in the
art of dynamic balancers.
Description of FIG. 10
[0129] FIG. 10 discloses a flowmeter 1000 that is identical to
flowmeter 900 except that the dynamic balancers of FIG. 10 are of
the active type (ADB) and are designated 1032 and 1033. These
active dynamic balancers are controlled by an exchange of signals
with meter electronics 1021 over paths 1023, 1024, 1025 and 1026.
Meter electronics 1021 receives signals over path 1023 from active
dynamic balancer 1032 representing the vibrations
[0130] applied by the dynamically unbalanced vibrating flow tube
1002 to leg 1017. Meter electronics receive these signals and
generates a control signal that is applied over path 1024 to active
dynamic balancer 1032 to counteract the flow tube vibrations.
Operating in this manner, active dynamic balancer 1032 can be
controlled to reduce the vibrations of leg 1017 to whatever
magnitude may be desired so that the resulting mass of base 1001
may be of an acceptable level for commercial use of flowmeter 1000.
The active dynamic balancer 1033 mounted atop leg 1018 of base 1001
operates in the same manner as described for the active dynamic
balancer mounted to leg 1017.
Description of FIG. 11
[0131] FIG. 11 discloses yet another alternative embodiment
comprising a flowmeter 1100 having dual flow tubes 1101, 1102 which
are substantially U-Shaped and have right side legs 1103, 1104 and
left side legs 1105, 1106. The bottom portion of the side legs are
connected to form "Y" sections 1107 and 1108 which may be connected
to a suitable base not shown to minimize drawing complexity. The
dual flow tubes of flowmeter 1100 vibrate as dynamically balanced
elements around the axes W-W and W'-W' of brace bars 1109 and 1110.
Flow tubes 1101 and 1102 are driven in phase opposition by driver D
affixed to the top portion of the U-shaped flow tubes. The Coriolis
deflections imparted by the vibrating material filled flow tubes
are detected by right pick-off RP0 and left pick-off LP0. Meter
electronics 1121 functions to apply signals over path 1123 to cause
driver D to vibrate flow tubes 1101, 1102 in phase opposition. The
Coriolis response detected by
pick-offs LP0 and RP0 as transmitted over paths 1122, 1124 to meter
electronics 1121 which processes the signals and derives material
flow information which is transmitted over output path 1124 to a
utilizations circuit not shown.
Description of FIGS. 12 and 13
[0132] FIGS. 12 and 13 disclose a dynamically balanced flowmeter
1200 having a pair of flow tubes 1201 and 1202 which are vibrated
in phase opposition by driver D. The flow tubes receive a material
flow; driver D vibrates the flow tubes in phase opposition in
response to a drive signal received over path 1223 from meter
electronics 1221. The Coriolis response of the material filled
vibrating flow tubes is detected by pick-offs LP0 and RP0 with
their output being applied over conductors 1221 and 1224 to meter
electronics which processes the received signals to generate
material flow information that is applied over output path 1225 to
a utilization circuit not shown.
Description of FIG. 14
[0133] FIG. 14 discloses an alternative embodiment 1400 of the
invention comprising a massive base 1401 having an outer pair of
upwardly extending sidewalls 1443 and 1444 as well as an inner pair
of upwardly extending sidewalls 1417 and 1418. A single flow tube
1402 extends from an input process connection 1408 on the left
through the four upwardly extending sidewalls to an output process
connection 1409 on the right. The flow tube 1402 is vibrated by
driver D with the resulting Coriolis deflections of the vibrating
flow tube with material flow being detected by pickoffs LP0 and RP0
which transmit signals over the indicated paths to meter
electronics 1421 which functions in the same manner as priorly
described or FIG. 1. Temperature sensing element RTD senses the
temperature of the material filled flow tube and transmits this
information over path 1425 to meter electronics 1421.
[0134] The flowmeter of FIG. 14 differs from that of FIG. 1 in two
notable respects. The first is that the embodiment of FIG. 14 is
only a single flow tube 1402. The material flow extends through
this flow tube from input process connection 1408; the output of
the flow tube is applied via output process connection 1409 to
output tube 1406 for delivery to a user. The embodiment of FIG. 14
does not have the return flow tube comparable to element 103 of
FIG. 1.
[0135] Also, the massive base 1401 has two pairs of upwardly
extending walls whereas in the embodiment of FIG. 1 the massive
base 101 had only the single pair of upwardly extending walls 117
and 118. The single pair of walls in FIG. 1 performed the function
of being a zero motion vibrational node as well as a mounting for
process connections 107 through 110. On FIG. 14, the inner pair of
walls 1417 and 1418 function as a zero motion vibrational node for
the ends of the active portion of flow tube 102. The outer pair of
upwardly extending walls 1443 and 1444 mount process connections
1408 on the left and 1409 on the right.
[0136] When in use, process material is received from tube 1404
connected to process connection 1408. The inlet of flow tube 1402
is also connected to process connection 1408. Flow tube 1402
extends the process material flow to the right through the two
pairs of sidewalls to output process connection 1409 to which is
connected the output tube 1406.
[0137] The part numbers on FIG. 14 not specifically mentioned
immediately above are analogous to and perform the functions
identical to their corresponding elements on the previous FIGS.
including FIG. 1.
Description of FIG. 15
[0138] FIG. 15 discloses an alternative embodiment 1500 which is
similar in most respects to the embodiment of FIG. 1. The primary
difference is that in the embodiment of 1500, the rear flow tube
1503 is not dormant as is return tube 103 of the embodiment of FIG.
1. Instead, on FIG. 15, rear tube 1503 is vibrated by its driver DA
with the resulting Coriolis deflections of this vibrating tube with
material flow being detected by its pickoffs LP0A and RP0A. Their
output signals are transmitted over paths 1542 and 1544 to meter
electronics 1521 which receives these signals as well as signals
from pickoffs LP0 and RP0 of flow tube 1502 to generate material
flow information.
[0139] The process material flows to right on FIG. 15 through flow
tube 1502, through tube 1500 and flows to the left through flow
tube 1503. This phase reversal of mated pickoffs can be compensated
by reversing the connections to pickoffs LP0A and RP0A so that the
Coriolis signals from all pickoffs received by meter electronics
1521 are additive to enhance meter sensitivity.
[0140] The parts shown on FIG. 15 not specifically mentioned above
are identical in function to their corresponding elements on FIG.
15.
Description of FIG. 16
[0141] FIG. 16 discloses an alternative embodiment 1600 that is
similar to the embodiment of FIG. 14. The differences are that
upwardly extending inner mounting posts 1617 and 1618 replace walls
1417 and 1418 of FIG. 14. Also upwardly extending outer mounting
posts 1643 and 1645 replace walls 1443 and 1445 of FIG. 14. Outer
posts 1643 and 1645 prevent flow tube 1602 from pivoting about post
1617 and 1618 as an axis. Connectors 1608 and 1609 are optional and
if desired flow tube 1602 may extend outwardly through posts 1643
and 1645 and replace inlet tube 1604 and outlet tube 1402. The
extended flow tube may be connected downstream and upstream by a
user to the user=s equipment. When connected to users equipment the
flow tube 1602 can be attached to process connection 1608 and 1609
in a similar fashion as shown in detail in FIG. 4. In addition,
flow 1602 tube can be attached to process connections similar in
design as described in FIG. 4. with the nipple and movable portion
of the process connection being located at each end. This allows a
compression fitting from flow tube 1602 to the process connection
and also a compression fitting from the users equipment to the same
process connection. Posts 1443 and 1445 serve as a mounting for
connector 1608 and 1609 when provided.
[0142] It is to be expressly understood that the claimed invention
is not to be limited to the description of the preferred embodiment
but encompasses other modifications and alterations within the
scope and spirit of the inventive concept. For example, the
flowmeter embodiments shown herein may be operated in an upside
down orientation it is desired to have the driver D positioned on
top of a vibrating flow tube to allow the driver heat to move
upward away from the flow tube. This can better isolate the flow
tube from thermal stress that might degrade the accuracy or the
output data of the flowmeter. Also, the Coriolis flowmeter herein
disclosed has applications other than those herein disclosed. For
example the disclosed Coriolis flowmeter may be used in
applications in which the flowing process material is corrosive,
such as nitric acid, and incompatible for use with flow meters
having a metal wetted flow path.
* * * * *